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    Abu-Zeid, M.E., Rakhshani, A.E., Al-Jassar, A.A., and Youssef, Y.A.
    Determination of the Thickness and Refractive Index of Cu2O Thin Film Using Thermal and Optical Interferometry 1986 Physica Status Solidi (a)
    Vol. 93, pp. 613-620 
    article DOI  
    Adachi, H. and Takano, M.
    Cluster model investigation of the electronic state and chemical bond in cuprous and cupric oxide 1989 Physica C
    Vol. 157(1), pp. 169-179 
    article DOI  
    Abstract: Cluster model calculations have been carried out to study the electronic state and the chemical bonding in Cu2O and CuO as well as YBa2Cu3O7 and YBa2Cu3O6. The clusters used are Cu4O14-9, Cu4O16-12, Cu3O17-12 and Cu3O15-10, respectively, each being embedded in an appropriate electrostatic potential reflecting the crystal structure. The covalent interaction between Cu and O is most significant in the cluster for the high-temperature superconductor YBa2CuO7. It is remarkable that O 2p[pi] holes are created near the Fermi level and stabilized in the O----Cu+---O- linear bond formed in the basal Cu2O plane of the cluster for YBa2Cu3O7. A charge disproportionation takes place both in the model clusters for YBa2Cu3O7 and YBa2Cu3O6, while a spin polarization is seen only in the latter. The similarity and dissimilarity of Cu atoms in those oxides are discussed.
    Agekyan, V.T., Monozon, B.S., and Shiryapov, I.P.
    The Fine Structure of Wannier-Mott Excitons in a Cubic Crystal and Its Behaviour in an Electric Field 1974 Physica Status Solidi (b)
    Vol. 66(1), pp. 359-370 
    article DOI  
    Abstract: The anisotropy of the forbidden transitions in the absorption spectrum of the exciton yellow series of cuprous oxide in an electric field has been studied. The group-theoretical analysis of electric field effect on transitions with different orbital quantum numbers l makes it possible to reveal the P-, S-, and D-series of exciton levels on the basis of experimental data. The position of dipole-active and -inactive levels has been determined by extrapolation to zero field, which enables one to study the l-splitting in a cubic crystal. With the l-splitting, the P-series remains exactly hydrogen-like, the D-series preserves an approximate hydrogen-like behaviour, and the S-series looses its hydrogen-like behaviour.
    Agekyan, V.T., Kuz'mina, I.P., Lobachev, A.N., Predtechenskii, B.S., Starostina, L.S., and Khaidukov, N.M.
    Optical Properties of Cuprous Oxide Crystals Grown by Various Methods 1975 Journal of Applied Spectroscopy
    Vol. 22, pp. 562-566 
    article DOI  
    Agekyan, V.T. and Stepanov, Y.A.
    Exchange interaction in exciton excited $S$ states 1975 JETP Letters
    Vol. 21, pp. 127-128 
    article URL 
    Agekyan, V.T.
    Spectroscopic properties of semiconductor crystals with direct forbidden energy gap 1977 Physica Status Solidi (a)
    Vol. 43, pp. 11 
    article DOI  
    Agekyan, V.F., Vasil'ev, N.N., and Stepanov, Y.A.
    Screening of excitons in cuprous oxide 1981 JETP Letters
    Vol. 33, pp. 14-17 
    article URL 
    Aggarwal, S., Töpfer, J., Tsai, T.-L., and Dieckmann, R.
    Point defects and transport in binary and ternary, non-stoichiometric oxides 1997 Solid State Ionics
    Vol. 101-103, pp. 321-331 
    article DOI  
    Aggarwal, S. and Dieckmann, R.
    Contributions of Bulk and Near-Boundary Regions to the Variation of the Oxygen Content in Cu$_2-delta$O 1997   unpublished URL 
    Akhavan, O., Tohidi, H., and Moshfegh, A.Z.
    Synthesis and electrochromic study of sol-gel cuprous oxide nanoparticles accumulated on silica thin film 2009 Thin Solid Films
    Vol. 517(24), pp. 6700-6706 
    article DOI  
    Abstract: In this study, electrochromic properties of cuprous oxide nanoparticles, self-accumulated on the surface of a sol-gel silica thin film, have been investigated by using UV-visible spectrophotometry in a lithium-based electrolyte cell. The cuprous oxide nanoparticles showed a reversible electrochromic process with a thin film transmission reduction of about 50% in a narrow wavelength range of 400-500 nm, as compared to the bleached state of the film. Using optical transmission measurement, we have found that the band gap energy of the films reduced from 2.7 eV for Cu2O to 1.3 eV for CuO by increasing the annealing temperature from 220 to 300 °C in an N2 environment for 1 h. Study of the band gaps of the as-deposited, colored and bleached states of the nanoparticles showed that the electrochromic process corresponded to a reversible red-ox conversion of Cu2O to CuO on the film surface, in addition to the reversible red-ox reaction of the Cu2O film. X-ray photoelectron spectroscopy indicated that the copper oxide nanoparticles accumulated on the film surface, after annealing the samples at 200 °C. Surface morphology of the films and particle size of the surface copper oxides have also been studied by atomic force microscopy analysis. The copper oxide nanoparticles with average size of about 100 nm increased the surface area ratio and surface roughness of the silica films from 2.2% and 0.8 nm to 51% and 21 nm, respectively.
    Akimoto, K., Ishizuka, S., Yanagita, M., Nawa, Y., Paul, G.K., and Sakurai, T.
    Thin film deposition of Cu2O and application for solar cells 2006 Solar Energy
    Vol. 80, pp. 715-722 
    article DOI  
    Al-Kuhaili, M.F.
    Characterization of copper oxide thin films deposited by the thermal evaporation of cuprous oxide (Cu2O) 2008 Vacuum
    Vol. 82(6), pp. 623-629 
    article DOI  
    Abstract: Thin films of copper oxide were deposited by thermal evaporation of cuprous oxide (Cu2O) powder. The substrates were either unheated or heated to a temperature of 300 °C. The films were also annealed in air at a temperature of 500 °C for 3 h. The films were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and UV-visible spectrophotometry. The effects of the substrate temperature and post-deposition annealing on the chemical, structural and optical properties of the films were investigated. As-deposited films on unheated substrates consisted of mixed cupric oxide (CuO) and Cu2O phases, with a higher concentration of the Cu2O phase. However, the films deposited on heated substrates and the annealed films were predominantly of the CuO phase.
    Altarawneh, M., Radny, M.W., Smith, P.V., Mackie, J.C., Kennedy, E.M., Dlugogorski, B.Z., Soon, A., and Stampfl, C.
    Adsorption of 2-chlorophenol on Cu2O(111)-Cu$_CUS$: A first-principles density functional study 2010 Applied Surface ScienceProceedings of the 4th International Workshop on Surface Physics "Surfaces and Nanostructures"
    Vol. 256(15), pp. 4764-4770 
    article DOI  
    Abstract: First-principles density functional theory and a periodic-slab model have been utilized to investigate the adsorption of a 2-chlorophenol molecule on a CuO(1�1�1) surface with a vacant Cu surface site, namely Cu2O(1�1�1)-CuCUS. Several vertical and flat orientations have been studied. All of these molecular configurations interact very weakly with the Cu2O(1�1�1)-CuCUS surface, an observation which also holds for clean copper surfaces and the Cu2O(1�1�0):CuO surface. Hydroxyl-bond dissociation assisted by the surface was found to be endoergic by 0.42-1.72�eV, depending predominantly on the position of the isolated H on the surface. In addition, the corresponding adsorbed 2-chlorophenoxy moiety was found to be more stable than a vacuum 2-chlorophenoxy radical by about 0.76�eV. Despite these predicted endoergicities, however, we would predict the formation of 2-chlorophenoxy radicals from gaseous 2-chlorophenol over the copper (I) oxide Cu2O(1�1�1)-CuCUS surface to be a feasible and important process in the formation of PCDD/Fs in the post-flame region where gas-phase routes are negligible.
    Amekura, H. and Masumi, T.
    Reconfirmation with Discussion of Anomalies in Photoconductivity of Cu2O at Low Temperatures 1995 Journal of the Physical Society of Japan
    Vol. 64, pp. 2684-2696 
    article DOI  
    Amekura, H., Umeda, N., Takeda, Y., and Kishimoto, N.
    Optical transitions of Cu2O nanocrystals in SiO2 fabricated by ion implantation and two-step annealing 2006 Applied Physics Letters
    Vol. 89, pp. 223120 
    article DOI  
    Anderson, J.S. and Greenwood, N.N.
    The Semiconducting Properties of Cuprous Oxide 1952 Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences
    Vol. 215, pp. 353-370 
    article URL 
    Andrievskii, A.I., Voloshchenko, V.I., and Mishchenko, M.T.
    1953 Doklady Akademii Nauk SSSR
    Vol. 90, pp. 521 
    Andrievskii, A.I. and Pidorya, M.M.
    Calculation of the Debye temperature of Cu2O from elastic constants 1967 Russian Physics Journal
    Vol. 10, pp. 67-68 
    article DOI  
    Angello, S.J.
    Hall effect and Conductivity of Cuprous Oxide 1942 Physical Review
    Vol. 62, pp. 371-377 
    article DOI  
    Antony, J., Qiang, Y., Faheem, M., Meyer, D., McCready, D.E., and Engelhard, M.H.
    Ferromagnetic semiconductor nanoclusters: Co-doped Cu2O 2007 Applied Physics Letters
    Vol. 90, pp. 013106 
    article DOI  
    Apfel, J.H. and Portis, A.M.
    Exciton-Induced Photoconductivity In Cu2O 1960 Journal of Physics and Chemistry of Solids
    Vol. 15, pp. 33-38 
    article DOI  
    Arbuzova, T., Smolyak, I., Naumov, S., and Samokhvalov, A.
    Effect of doping on the magnetic properties of the low-dimensional antiferromagnet CuO 1998 Physics of the Solid State
    Vol. 40(10), pp. 1702-1705 
    article DOI  
    Abstract: Abstract  The effect of doping with Li+, Zn2+, Ni2+, and Ga3+ ions on the magnetic susceptibility of the low-dimensional antiferromagnet CuO (T N=230 K) has been studied within a broad temperature range of 77–600 K. The solubility of impurity ions in the CuO lattice is low, ⩽3%. Impurity ions, similar to intrinsic defects, distort antiferromagnetic coupling and can shift the long-and short-range magnetic-order regions toward lower T.
    Arbuzova, T., Naumov, S., and Kozlov, E.
    Elastic-stress relaxation in compacted nanocrystalline CuO 2005 Physics of the Solid State
    Vol. 47(7), pp. 1358-1364 
    article DOI  
    Abstract: Abstract  The magnetic properties of two types of nanocrystalline antiferromagnetic CuO samples, namely, dense nanoceramics and loose powders, were studied. For nanomaterials with smaller particles, the magnetic susceptibility χ was shown to increase with a decrease in temperature T < T N. The increase in χ in both series of samples is related to the disordering of Cu2+ spins at the surfaces of nanoparticles. The magnetic properties of nanopowders characterize the properties of isolated nanoparticles. In a dense nanoceramic, the size effect is compensated for by the interaction between nanoparticles. The magnetic properties of nanoceramics are determined by elastic stresses induced by an external action. Elastic-stress relaxation results in the recovery of magnetic order and decreases the magnetic susceptibility.
    Arbuzova, T., Naumov, S., and Arbuzov, V.
    Relaxation of radiation-induced defects in CuO 2009 JETP Letters
    Vol. 89(8), pp. 414-418 
    article DOI  
    Abstract: Abstract  The relaxation of radiation-induced defects in the CuO polycrystal and nanoceramic with the particle size d = 15 nm irradiated by an electron dose of F = 5 × 1018 cm−2 has been studied. In the irradiated samples, a strong susceptibility increase with decreasing temperature T < 150 K is observed. This increase is due to the formation of ferromagnetic polarons in the antiferromagnetic matrix near the defects. The structural symmetry distortion makes the samples unstable. The time variations of the magnetic properties in the CuO samples prepared by different methods are compared.
    Arbuzova, T., Naumov, S., Arbuzov, V., and Druzhkov, A.
    Anomalous magnetic properties of electron-irradiated antiferromagnetic copper monoxide 2009 Physics of the Solid State
    Vol. 51(5), pp. 953-960 
    article DOI  
    Abstract: Abstract  The influence of radiation defects on the magnetic properties of polycrystalline CuO and a high density nanoceramic with crystallite sizes d = 5 and 15 nm has been studied in the temperature range T = 77–300 K. Electron irradiation at fluences Φ = 5 × 1018 cm−2 initiated an increase in the susceptibility χ ∼ 1/T below 150 K, a feature anomalous for 3D antiferromagnets. The nonlinear behavior of magnetization in weak fields, the increase in the magnetic moment with decreasing temperature, and observation of the spontaneous magnetic moment at temperatures T < 150 K can be attributed to local changes in the exchange parameters and the formation of clusters with uncompensated magnetic moments in the antiferromagnetic matrix near point defects.
    Artioli, G., Dapiaggi, M., Fornasini, P., Sanson, A., Rocca, F., and Merli, M.
    Negative thermal expansion in cuprite-type compounds: A combined synchrotron XRPD, EXAFS, and computational study of Cu2O and Ag2O 2006 Journal of Physics and Chemistry of Solids
    Vol. 67, pp. 1918-1922 
    article DOI  
    Assimos, J.A.
    Investigation of slow changes in the electrical conductivity and Hall constant of single crystal cuprous oxide 1965 School: Wayne State University, Dept. of Chemistry  mastersthesis  
    Assimos, J.A. and Trivich, D.
    Photovoltaic properties and barrier heights of single crystals and polycrystalline Cu2O-Cu contacts 1973 Journal of Applied Physics
    Vol. 44, pp. 1687-1693 
    article DOI  
    Assimos, J.A.
    An investigation of the photoelectric threshold, work function and bulk Fermi level of single-crystal cuprous oxide, and the photovoltaic properties of single-crystal and polycrystalline cuprous oxide-copper contacts 1973 School: Wayne State University, Dept. of Chemistry  phdthesis  
    Assimos, J.A. and Trivich, D.
    The Photoelectric Threshold, Work Function, and Surface Barrier Potential of Single-Crystal Cuprous Oxide 1974 Physica Status Solidi (a)
    Vol. 26, pp. 477-488 
    article DOI  
    Aygün, S. and Cann, D.
    Response Kinetics of Doped CuO/ZnO Heterocontacts 2005 The Journal of Physical Chemistry B
    Vol. 109(16), pp. 7878-7882 
    article DOI  
    Abstract: In this work, the effects of doping on hydrogen sensitivity and sensor response of CuO/ZnO heterocontacts were examined. Both current−voltage and current−time measurements were utilized in hydrogen/air and hydrogen/nitrogen atmospheres at 400 °C. The addition of Ni to p-type CuO and Ga to n-type ZnO were observed to enhance the sensor properties. Through analysis of the time-dependent current data, it was shown that the sensor response of the heterocontact can be modeled via a two-site Langmuir adsorption model. The response times of the two sites were calculated using this model. While one of the sites showed a significant decrease in response time when the p-side was doped with Ni, the response time of the other site changed only slightly. The highest sensitivity was obtained by doping the n-side with Ga at the expense of the response rate. The fastest response times were achieved when both sides of the heterocontact were doped. This suggests that carrier density may play a significant role in the sensor response.
    Balamurugan, B. and Mehta, B.R.
    Optical and structural properties of nanocrystalline copper oxide thin films prepared by activated reactive evaporation 2001 Thin Solid Films
    Vol. 396, pp. 90-96 
    article DOI  
    Balamurugan, B., Mehta, B.R., Avasthi, D.K., Singh, F., Arora, A.K., Rajalakshmi, M., Raghavan, G., Tyagi, A.K., and Shivaprasad, S.M.
    Modifying the nanocrystalline characteristics---structure, size, and surface states of copper oxide thin films by high-energy heavy-ion irradiation 2002 Journal of Applied Physics
    Vol. 92, pp. 3304-3310 
    article DOI  
    Balamurugan, B., Aruna, I., Mehta, B.R., and Shivaprasad, S.M.
    Size-dependent conductivity-type inversion in Cu2O nanoparticles 2004 Physical Review B
    Vol. 69, pp. 165419 
    article DOI  
    Baldassarri Höger von Högersthal, G., Fröhlich, D., Kulka, M., Auer, T., Bayer, M., and Stolz, H.
    Acoustic and optical phonon scattering of the $1S$ yellow orthoexciton in Cu2O 2006 Physical Review B
    Vol. 73, pp. 035202 
    article DOI  
    Balili, R., Hartwell, V., Snoke, D., Pfeiffer, L., and West, K.
    Bose-Einstein Condensation of Microcavity Polaritons in a Trap 2007 Science
    Vol. 316, pp. 1007-1010 
    article DOI  
    Balkanski, M., Petroff, Y., and Trivich, D.
    Optical properties of cuprous oxide in the ultra-violet 1967 Solid State Communications
    Vol. 5, pp. 85-88 
    article DOI  
    Balkanski, M., Nusimovici, M.A., and Reydellet, J.
    First order Raman spectrum of Cu2O 1969 Solid State Communications
    Vol. 7(11), pp. 815-818 
    article DOI  
    Abstract: Experimental determination of the Raman active mode in CU2O whose symmetry properties are studied by means of group theory considerations.
    Bandyopadhyay, S., Chatterjee, A.K., Saha, S.K., and Chatterjee, A.
    Comparative Compton scattering studies in Cu2O and Ag2O 1994 Journal of Physics: Condensed Matter
    Vol. 6, pp. 2403-2408 
    article DOI  
    Barbour, J.C., Braithwaite, J.W., and Wright, A.F.
    Determination of solid-state sulfidation mechanisms in ion-implanted copper 2001 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
    Vol. 175-177, pp. 382-387 
    article DOI  
    Bardeen, J., Brattain, W.H., and Shockley, W.
    Investigation of Oxidation of Copper by Use of Radioactive Cu Tracer 1946 The Journal of Chemical Physics
    Vol. 14, pp. 714-721 
    article DOI  
    Barker, M.G. and Paul Dawson, A.
    The reactions of the oxides Cu2O and CuO with potassium monoxide and liquid potassium 1979 Journal of the Less Common Metals
    Vol. 64(1), pp. 127-134 
    article DOI  
    Abstract: The ternary oxides KCuO and K4CuO3 have been observed as products in the solid state reactions of potassium oxide with the oxides Cu2O and CuO under argon and in vacuum. The compound K4CuO3 has been isolated as a single phase and its X-ray powder diffraction pattern has been obtained. Both Cu2O and CuO are reduced by liquid potassium to copper metal, with the formation of the ternary oxides KCuO and K4CuO3. Thermal analysis showed that Cu2O reacts with liquid potassium at 185 �C and that CuO undergoes the same reaction at 70 �C.
    Barman, S.R. and Sarma, D.D.
    Investigation of the L$_3$--M$_45$M$_45$ Auger spectra of Cu, Cu2O and CuO 1992 Journal of Physics: Condensed Matter
    Vol. 4, pp. 7607-7616 
    article DOI  
    Barreca, D., Fornasiero, P., Gasparotto, A., Gombac, V., Maccato, C., Montini, T., and Tondello, E.
    The Potential of Supported Cu2O and CuO Nanosystems in Photocatalytic H2 Production 2009 ChemSusChem
    Vol. 2(3), pp. 230-233 
    article DOI  
    Abstract: Hy wire: Supported Cu2O nanosystems and CuO nanowires obtained by chemical vapor deposition were used in the photocatalytic splitting of methanol/water solutions to produce hydrogen. The results obtained with these systems open appealing perspectives for the clean conversion of sunlight into storable chemical energy.
    Barton, V.P.
    Light Sensitivity of Cuprous Oxide and of Selenium 1924 Physical Review
    Vol. 23, pp. 337-344 
    article DOI  
    Bartos, A., Bolse, W., Lieb, K.P., and Uhrmacher, M.
    Electric Field Gradients of $^111$Cd in the Copper oxides CuO and Cu2O 1988 Physics Letters A
    Vol. 130, pp. 177-181 
    article DOI  
    Bassani, F., La Rocca, G.C., and Artoni, M.
    Electromagnetically induced transparency in bulk and microcavity semiconductors 2004 Journal of Luminescence
    Vol. 110, pp. 174-180 
    article DOI  
    Baumeister, P.W.
    Optical Absorption of Cuprous Oxide 1961 Physical Review
    Vol. 121, pp. 359-362 
    article DOI  
    Beg, M.M. and Shapiro, S.M.
    Study of phonon dispersion relations in cuprous oxide by inelastic neutron scattering 1976 Physical Review B
    Vol. 13, pp. 1728-1734 
    article DOI  
    Bellakhal, N., Draou, K., and Brisset, J.L.
    Electrochemical investigation of copper oxide films formed by oxygen plasma treatment 1997 Journal of Applied Electrochemistry
    Vol. 27, pp. 414-421 
    article DOI  
    Berezin, A.A. and Weichman, F.L.
    Photovoltaic effect in cuprous oxide--copper junctions in relation to the optical absorption spectrum of cuprous oxide 1981 Solid State Communications
    Vol. 37, pp. 157-160 
    article DOI  
    Berger, J.
    Comportement thermoelastique de monocristaux de Cu2O 1978 Solid State Communications
    Vol. 26, pp. 403-405 
    article DOI  
    Bertocci, U.
    Photopotentials on Copper and Copper Alloy Electrodes 1978 Journal of the Electrochemical Society
    Vol. 125(10), pp. 1598 - 1602 
    article DOI  
    Bharadwaj, M.D. and Yang, J.C.
    The reduction of copper oxide by water vapor visualized by in situ UHV-TEM 2001 Scripta Materialia
    Vol. 44(11), pp. 2557-2561 
    article DOI  
    Bianchi, A.E., Plivelic, T.S., Punte, G., and Torriani, I.L.
    Probing the structure of nanograined CuO powders 2008 Journal of Materials Science
    Vol. 43, pp. 3704-3712 
    article DOI  
    Abstract: The microstructural properties of polycrystal-
    line CuO powders and their evolution during controlled high
    energetic ball milling (HEBM) were studied using conven-
    tional X-ray diffraction (XRD) techniques and in situ
    temperature-dependent small and wide angle scattering
    (SAXS–WAXS) synchrotron radiation experiments. Vol-
    ume weighted average grain size, unit cell expansion,
    oxygen deficiency, and microstrain values as a function of
    milling time were obtained from XRD. SAXS data revealed
    different nanostructures for samples synthesized by one-step
    solid-state reaction (SSR) or HEBM-treated powders. The
    latter presented the characteristics of a multilayered nano-
    scale solid system with surface fractal behavior. Correlation
    of the XRD microstructural parameters and the power law
    exponent of the SAXS curves as a function of temperature
    and milling time provided a coherent picture of the structure
    of HEBM-treated powders. The overall structural informa-
    tion presented in this article may shed some light on the
    macroscopic physical properties of CuO nanostructures.
    Biccari, F., Malerba, C., and Mittiga, A.
    Metastability Effects in Cu2O Solar Cells 2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain, pp. 583-587  inproceedings DOI  
    Biccari, F., Malerba, C., and Mittiga, A.
    Chlorine doping of Cu2O 2010 Solar Energy Materials and Solar Cells  article DOI  
    Abstract: Cu2O is a semiconductor suitable for photovoltaic applications. However, the highest efficiency obtained for a solar cell based on Cu2O is, to date, one order of magnitude lower than its theoretical limit. This could be due to the difficulties in the doping processes. In this paper we investigate the effects of chlorine doping on Cu2O. The doped material has a conductivity about one order of magnitude greater than the undoped material. The measurements of the carrier concentration as a function of temperature suggest that chlorine acts both as a donor, substituting the oxygen, and as an acceptor, sitting in an interstitial position. Moreover the p-type persistent photo-conductivity (PPC), shown by undoped samples after illumination, is very weak in the doped samples and it has a much longer decay time. Finally the effect of chlorine doping on the minority carrier lifetime is investigated by measurements of external quantum efficiency on Schottky junctions and the possible role of excitons is also discussed.
    Bijani, S., Gabás, M., Martínez, L., Ramos-Barrado, J.R., Morales, J., and Sánchez, L.
    Nanostructured Cu2O thin film electrodes prepared by electrodeposition for rechargeable lithium batteries 2007 Thin Solid Films
    Vol. 515, pp. 5505-5511 
    article DOI  
    Abstract: UniformfilmsofCu2Owiththicknessbelow1 $mwerepreparedfromaCu(II)lactatesolution.Thedepositswerecompactandofhighpurity
    Bisht, V., Rajeev, K.P., and Banerjee, S.
    Anomalous magnetic behavior of CuO nanoparticles 2010 Solid State Communications
    Vol. 150, pp. 884-887 
    article DOI  
    Abstract: We report studies on temperature, field and time dependence of magnetization on cupric oxide nanoparticles of sizes 9 nm, 13 nm and 16 nm. The nanoparticles show unusual features in comparison to other antiferromagnetic nanoparticle systems. The field cooled (FC) and zero field cooled (ZFC) magnetization curves bifurcate well above the Néel temperature and the usual peak in the ZFC magnetization curve is absent. The system does not show any memory effects which is in sharp contrast to the usual behavior shown by other antiferromagnetic nanoparticles. It turns out that the non-equilibrium behavior of CuO nanoparticles is very strange and is neither superparamagnetic nor spin glass-like.
    Blank, Z. and Brenner, W.
    Growth of Single Crystals of Cuprous Oxide in Silica Gels at Near Ambient Temperatures 1969 Nature
    Vol. 222, pp. 79-80 
    article DOI  
    Bloch, P.D. and Schwab, C.
    Direct Evidence for Phonon-Assisted Transitions to the $1s$ Paraexciton Level of the Yellow Exciton Series in Cu2O 1978 Physical Review Letters
    Vol. 41, pp. 514-517 
    article DOI  
    Bloem, J., Van der Houven van Oordt, A.J., and Kröger, F.A.
    A new luminescence emission in Cu2O 1956 Physica
    Vol. 22(6-12), pp. 1254-1256 
    article DOI  
    Bloem, J.
    Discussion of Some Optical and Electrical Properties of Cu2O 1958 Philips Research Reports
    Vol. 13, pp. 167-193 
    Bohannan, E.W., Huang, L.-Y., Miller, F.S., Shumsky, M.G., and Switzer, J.A.
    In Situ Electrochemical Quartz Crystal Microbalance Study of Potential Oscillations during the Electrodeposition of Cu/Cu2O Layered Nanostructures 1999 Langmuir
    Vol. 15, pp. 813-818 
    article DOI  
    Borgohain, K., Singh, J.B., Rama Rao, M.V., Shripathi, T., and Mahamuni, S.
    Quantum size effects in CuO nanoparticles 2000 Physical Review B
    Vol. 61(16), pp. 11093 
    article DOI  
    Abstract: Size effects in cupric oxide nanocrystals, synthesized using a novel electrochemical route, having average diameters of about 4 and 6 nm, are probed by x-ray photoelectron spectroscopy. Cu—O bond ionicity was found to increase with reduction in nanocrystallite size. Formation of pure CuO phase was confirmed from x-ray diffraction, infrared spectrophotometry and photoelectron spectroscopy. This report also disproves the earlier conjecture that nanometer sized CuO phase is unstable below 25 nm.
    Borgohain, K., Murase, N., and Mahamuni, S.
    Synthesis and properties of Cu2O quantum particles 2002 Journal of Applied Physics
    Vol. 92, pp. 1292-1297 
    article DOI  
    Abstract: Cuprous oxide quantum particles as small as 2 nm (comparable to the Bohr exciton radius) were synthesized using an electrochemical route. Quantum confinement effects are evident from a blueshift in the optical absorption. The optical absorption spectra of Cu2O nanoparticles of different sizes are discussed. Structural analysis by x-ray diffraction as well as electron diffraction shows the nanoparticles to be cubic and single phased Cu2O. X-ray photoelectron spectroscopic studies indicate the presence of CuO on the surface of Cu2O core nanoparticles.
    Bose, S.K., Mitra, S.K., and Roy, S.K.
    Effect of short-circuiting on the oxidation kinetics of copper and its doped varieties in the temperature range of $523-1073$ K 1996 Oxidation of Metals
    Vol. 46, pp. 73-107 
    article DOI  
    Böttger, O.
    Über die Halbleitereigenschaften des Kupferoxyduls. IV Leitfähigkeitsmessungen bei hohen Temperaturen 1952 Annalen der Physik
    Vol. 445, pp. 232-240 
    article DOI  
    Brahms, S. and Nikitine, S.
    Intrinsic absorption and reflection of cuprous oxide in the $2.5$ to $6.5eV$ region 1965 Solid State Communications
    Vol. 3, pp. 209-212 
    article DOI  
    Abstract: Not Available
    Brahms, S., Nikitine, S., and Dahl, J.P.
    On the band structure and the absorption spectrum of Cu2O 1966 Physics Letters
    Vol. 22, pp. 31-33 
    article DOI  
    Brahms, S., Dahl, J.P., and Nikitine, S.
    Vol. 28(C3), pp. C3-32-C3-35 
    article DOI  
    Brahms, S. and Cardona, M.
    Electric Field Effects On Optical Transitions To The $n=1$ Exciton In Cuprous Oxide 1968 Solid State Communications
    Vol. 6, pp. 733-736 
    article DOI  
    Brahms, S.
    Electric Field Effects on Excitons in Cuprous Oxide 1972 Physica Status Solidi (b)
    Vol. 51, pp. 509-520 
    article DOI  
    Abstract: Not Available
    Bratescu, M.A., Allred, D.B., Saito, N., Sarikaya, M., and Takai, O.
    Attenuated total reflectance spectroscopy of simultaneous processes: Corrosion inhibition of cuprous oxide by benzotriazole 2008 Applied Surface Science
    Vol. 254(10), pp. 2960-2966 
    article DOI  
    Abstract: Attenuated total reflectance (ATR) spectroscopy was used to perform in situ studies of the corrosion inhibition of cuprous oxide (Cu2O) by benzotriazole (BTA) in aqueous solution at concentrations from 1 to 20 [mu]M. Because two separate processes occur simultaneously, that of Cu2O corrosion and corrosion inhibition by BTA adsorption, the spectral information was subjected to deconvolution by a conjugate gradient minimization algorithm. Under these conditions, a solution phase concentration of 7-10 [mu]M BTA nearly completely inhibited the corrosion of Cu2O in deionized water. Using a Langmuir adsorption model, this represented only 25% of the maximally covered surface area.
    Brattain, W.H.
    Specific resistance of cuprous oxide 1934 Physical Review
    Vol. 45, pp. 745 
    article DOI  
    Brattain, W.H.
    The Copper Oxide Rectifier 1951 Review of Modern Physics
    Vol. 23, pp. 203-212 
    article DOI  
    Bretheau, P.T., Marhic, C., Spendel, M., and Castaing, J.
    Fluage à haute température de monocristaux d'oxyde cuivreux 1977 Philosophical Magazine
    Vol. 35, pp. 1473-1487 
    article DOI  
    Bretheau, T. and Dolin, C.
    Heterogeneous deformation of Cu2O single crystals during high temperature compression creep 1978 Journal of Materials Science
    Vol. 13, pp. 587-593 
    article DOI  
    Abstract: Not Available
    Bretheau, T., Pellissiera, B., and Sieber, B.
    Plastic properties of Cu2O, mechanical tests and transmission electron microscopy --- II. High temperature 1981 Acta Metallurgica
    Vol. 29, pp. 1617-1629 
    article DOI  
    Briskman, R.N.
    A study of electrodeposited cuprous oxide photovoltaic cells 1992 Solar Energy Materials and Solar Cells
    Vol. 27(4), pp. 361-368 
    article DOI  
    Abstract: Cu2O---Cu backwall photovoltaic cells were made by cathodically electrodepositing Cu2O films on Cu substrates using an alkaline solution of chelated cupric ions. The best cells exhibited a Voc (open-circuit voltage) of 380 mV and a Jsc (short-circuit current density) of 600 gmA/cm2 with AM1 insolation. The presence of ethylene glycol in the plating electrolyte appears to be a necessary condition to obtain largem Voc and Jsc.
    Brower, W.S. and Parker, H.S.
    Growth of Single Crystal Cuprous Oxide 1971 Journal of Crystal Growth
    Vol. 8, pp. 227-229 
    article DOI  
    Bruneval, F.
    Exchange and Correlation in the Electronic Structure of Solids, from Silicon to Cuprous Oxide: GW Approximation and beyond 2005 School: Ecole Polytechnique, Palaiseau, France  phdthesis URL 
    Bruneval, F., Vast, N., Reining, L., Izquierdo, M., Sirotti, F., and Barrett, N.
    Exchange and Correlation Effects in Electronic Excitations of Cu2O 2006 Physical Review Letters
    Vol. 97(26), pp. 267601 
    article DOI  
    Abstract: State-of-the-art theoretical methods fail in describing the optical absorption spectrum, band gap, and optical onset of Cu2O. We have extended a recently proposed self-consistent quasiparticle approach, based on the GW approximation, to the calculation of optical spectra, including excitonic effects. The band structure compares favorably with our present angle-resolved photoemission measurements. The excitonic effects based on these realistic band structure and screening provide a reliable optical absorption spectrum, which allows for a revised interpretation of its main structures.
    Bubert, H., Grallath, E., Quentmeier, A., Wielunski, M., and Borucki, L.
    Comparative investigation on copper oxides by depth profiling using XPS, RBS and GDOES 1995 Fresenius' Journal of Analytical Chemistry
    Vol. 353(3), pp. 456-463 
    article DOI  
    Abstract: Depth profiling has been performed by using X-ray photoelectron spectrometry (XPS) in combination with Ar-ion sputtering, Rutherford backscattering spectrometry (RBS) and glow discharge optical emission spectrometry (GDOES). The data obtained by XPS have been subjected to factor analysis in order to determine the compositional layering of the copper oxides. This leads to two or three relevant components within the oxide layers consisting of Cu2O or CuO dependent on the sample preparation. GDOES measurements show sputtering profiles which are seriously influenced by a varying sputter rate. To ensure the results obtained so far, RBS measurements of the oxide layers have been carried out in order to discover artefacts of the other methods used and to demonstrate the excellent suitability of RBS for quantitative analysis of these layers. Chemical analysis consisting of (1) carrier-gas fusion analysis (CGFA) and (2) selective dissolution of Cu2O/CuO allows the determination of the total amount of oxygen and copper, respectively, and can serve as a cornerstone of quantitative analysis.
    Burlakov, V.M., Göppert, M., Jolk, A., Dinger, A., Becker, R., and Klingshirn, C.F.
    On a biphononic origin of the $1125cm^-1$ absorption band in cuprous oxide 1999 Physics Letters A
    Vol. 254, pp. 95-100 
    article DOI  
    Butov, L.V.
    Cold exciton gases in coupled quantum well structures 2007 Journal of Physics: Condensed Matter
    Vol. 19, pp. 295202 
    article DOI  
    Abstract: Cold exciton gases can be implemented in coupled quantum well structures. In this contribution, we review briefly the recent works on spontaneous coherence of cold excitons and on trapping of cold excitons with laser light.
    Cabrera, N. and Mott, N.F.
    Theory of the oxidation of metals 1949 Reports on Progress in Physics
    Vol. 12, pp. 163-184 
    article DOI  
    Abstract: Not Available
    Campbell, N.R.
    Recent improvements in photo--electric cells 1932 Journal of Scientific Instruments
    Vol. 9, pp. 369-373 
    article DOI  
    Campbell, R.H., Kass, W.J., and O'Keeffe, M.
    ``Interdiffusion Coefficients from Conductivity Measurements - Application to Cu2O'' in Mass Transport in Oxides 1968 , pp. 173-176  inbook  
    Campbell, R.H. and O'Keeffe, M.
    ``Kinetics of Vaporization of Cuprous Oxide'' in Kinetics of Ionic Reactions 1968 , pp. 413-421  inbook  
    Cao, Y., Fan, J., Bai, L., Yuan, F., and Chen, Y.
    Morphology Evolution of Cu$2$O from Octahedra to Hollow Structures 2010 Crystal Growth & Design
    Vol. 10(1), pp. 232-236 
    article DOI  
    Abstract: Octahedral Cu2O crystals with an edge length about 1 μm were synthesized by reducing a copper-citrate complex with glucose. The morphology and structure of Cu2O particles were greatly affected by the concentration of glucose, reaction temperature, and time. When the concentration of glucose increased from 0.6 to 1.6 M, the morphology of Cu2O could be changed from octahedral single crystals to spherical polycrystals. When the reaction time was prolonged from 6 to 36 h, solid Cu2O octahedra could be changed to a mixture of hollow Cu2O octahedra and irregular Cu particles. After removing Cu particles, pure Cu2O hollow octahedra could be obtained. The formation mechanism of hollow Cu2O octahedra was discussed. Similarly, hollow Cu2O spheres could also be obtained using this method. The prepared hollow octahedral Cu2O particles exhibited a higher photocatalytic activity for photodegradation of p-nitrophenol aqueous solution under visible-light illumination than other Cu2O particles with different morphologies (hollow spheres, solid octahedra, and solid spheres).
    Carabatos, C.
    Lattice Vibrations of Cu2O at the Long Wave Limit 1970 Physica Status Solidi (b)
    Vol. 37, pp. 773-779 
    article DOI  
    Abstract: Not Available
    Carabatos, C. and Prevot, B.
    Rigid ion model lattice dynamics of cuprite (Cu2O) 1971 Physica Status Solidi (b)
    Vol. 44, pp. 701-712 
    article DOI  
    Abstract: Not Available
    Carel, C., Mouallem-Bahout, M., and Gaudé, J.
    Re-examination of the non-stoichiometry and defect structure of copper(II) oxide or tenorite, Cu$_1pm z$O or CuO$_1pmepsilon$: A short review 1999 Solid State Ionics
    Vol. 117(1-2), pp. 47-55 
    article DOI  
    Abstract: Four sets of compositional data with a departure z or [epsilon] from the stoichiometry of tenorite Cu1�zO or CuO1�[epsilon] are re-examined for possible point defects. Correlations z(pO2) at equilibrium solid[left right double arrow]pure di-oxygen - when they can be computed - indicate the presence of either oxygen vacancies or copper interstitials or clusters of them. Some recent data after quenching are in favor of copper interstitials. Few data concerning tenorite prepared by decomposition of a salt, by oxidation of copper and by CVT in sealed tubes have generally been interpreted in the literature as indicating copper deficiency. In those oxides a large departure from the stoichiometry indicates a complex behavior likely due to several point defects possibly ordering at short and/or long range, and including chemical impurities in the case of sealed tube preparation. It is, however, in fact likely that the defect structure of such samples involves the two sub-lattices. Cu3O2- or Cu4O3-like clusters can even be envisaged.
    Castellan, G.W. and Moore, W.J.
    Diffusion of Radioactive Copper during Oxidation of Copper Foil 1949 The Journal of Chemical Physics
    Vol. 17, pp. 41-43 
    article DOI  
    Abstract: Not Available
    Caswell, N., Weiner, J.S., and Yu, P.Y.
    A study of non-thermalized luminescence spectra: the case of Cu2O 1981 Solid State Communications
    Vol. 40, pp. 843-846 
    article DOI  
    Abstract: Not Available
    Caswell, N. and Yu, P.Y.
    Physical origin of the anomalous temperature dependence of the $1S$ yellow exciton luminescence intensity in Cu2O 1982 Physical Review B
    Vol. 25(8), pp. 5519-5522 
    article DOI  
    Certier, M., Grun, J.B., and Nikitine, S.
    Etude de l'effet Zeeman de la raie $n = 1$ de la série jaune de Cu2O à $20^rcK$ 1964 Journal de Physique
    Vol. 25(4), pp. 361-365 
    article DOI  
    Abstract: The Zeeman effect of the exciton n = 1 line of the yellow series of Cu 2O has been studied at 20 °K, with polycrystalline samples and oriented single crystals. In the présence of a magnetic field of 30.5 kilogauss, the line is split into three components. The polarisation of these components is a function of the orientation of the field H, with respect to the symmetry axes of the crystal. The results are in good agreement with Elliott's theory. According to this theory, the irreducible representation of the exciton state is of the type Γ+25. The spectroscopic splitting factor of the line is g = 1.7 ± 0.2.
    Chan, H.Y.H., Takoudis, C.G., and Weaver, M.J.
    Oxide Film Formation and Oxygen Adsorption on Copper in Aqueous Media As Probed by Surface-Enhanced Raman Spectroscopy 1999 The Journal of Physical Chemistry B
    Vol. 103(2), pp. 357-365 
    article DOI  
    Chang, X., Ji, G., Shen, K., Pan, L., Shi, Y., and Zheng, Y.
    Fabrication of nanowire-like cuprous oxide in aqueous solutions of a triblock copolymer 2009 Journal of Alloys and Compounds
    Vol. 482(1-2), pp. 240-245 
    article DOI  
    Abstract: Cu2O nanowires were successfully fabricated by a simple liquid reaction in the presence of amphiphilic triblock copolymer (P123). The concentration of copolymer and aging time drastically changed the morphology of Cu2O samples. XPS results show that tiny amount of CuO as well as some absorbed O2 molecules existed on the surface of the Cu2O nanowires. Thermal analysis shows that the triblock copolymer owns a higher decomposition temperature (~645 °C) than that of pervious research results and this may be the result of strong interaction between P123 and Cu2O. The band gap of Cu2O nanowires was estimated about 2.23 eV and shifting of the band gap with decreasing of the particle size could also be found. The photoluminance property study reveals that the intrinsic emission peak of Cu2O nanowires can be observed at 546 nm under the excitation wavelength of 400 nm (Xe lamp was used as the excitation light source).
    Chaudhary, Y.S., Agrawal, A., Shrivastav, R., Satsangi, V.R., and Dass, S.
    A study on the photoelectrochemical properties of copper oxide thin films 2004 International Journal of Hydrogen Energy
    Vol. 29(2), pp. 131-134 
    article DOI  
    Abstract: The photoelectrochemical properties of Copper Oxide thin film, prepared by spray pyrolysis on conducting glass (SnO2: F-coated glass) substrate were investigated as a function of film deposition temperature and spray time. The variation in the deposition temperature affected the film morphology. The film deposited at substrate temperature 350�C exhibited better photoresponse than the films prepared at 300�C and 400�C. Creation of large number of dislocations and kink sites at 300�C and 400�C, which act as a recombination center for photogenerated electron has been held as a possible cause for poor photoresponse observed. The rise in photocurrent density with increase in spray time has been attributed to the increase in film thickness, which is probably allowing the film to absorb photons more efficiently. X-ray diffraction patterns of films confirm the presence of cupric oxide (CuO) phase. The films of CuO were found of n-type, apparently suggesting the existence of oxygen vacancies in the structure, on account of incomplete oxidation taking place at a relatively low temperatures (300-400�C).
    Chee, K.T. and Weichman, F.L.
    Pt-Cu2O-Cu double injection diodes 1977 Canadian Journal of Physics
    Vol. 55(7-8), pp. 727-734 
    article URL 
    Abstract: We report here on recent measurements made on our Pt–Cu2O–Cu diodes, annealed at an air pressure of 1 to 2 Torr, which we interpret as due to double injection, i.e. injection of holes from the platinum electrode and injection of electrons from the copper–Cu2O junction into the single crystal Cu2O region. The measurements discussed here include the forward I–V characteristics at various temperatures, current vs. thickness relationship at constant voltage, the effect of photo-memory on the I–V characteristics, and the discovery of a negative resistance regime at below room temperature at sufficiently high injection levels. The analysis of the temperature dependence of the current in the ohmic and the regimes, together with the effect of photomemory on the I–V characteristics enable us to identify the regime as the Ashley–Milnes regime with field dependent mobility.
    Chee, K.T., Keoesim, T., and Weichman, F.L.
    Electroluminescence from single crystal Cu2O diodes 1979 Canadian Journal of Physics
    Vol. 57(7), pp. 988-993 
    article URL 
    Abstract: We have measured the infrared electroluminescence in different types of single crystal Cu2O–Cu diodes under forward bias at various temperatures. Diodes which showed double-injection current-voltage characteristics in previous studies showed transient electroluminescence response at low currents and dc response at higher currents. On the other hand, diodes that showed the characteristics of single injection in previous studies showed transient electroluminescence response only. We have related the present studies on electroluminescence with the previous findings. Furthermore the present studies also revealed some information on the injection process. We have also discussed the differences and similarities between electroluminescence and photoluminescence of Cu2O.
    Chen, X.K., Irwin, J.C., and Franck, J.P.
    Evidence for a strong spin-phonon interaction in cupric oxide 1995 Physical Review B
    Vol. 52(18), pp. R13130 
    article DOI  
    Abstract: When CuO is cooled below its Néel temperature (TN2=213 K) the onset of long-range magnetic order effectively increases the unit-cell dimensions and additional peaks, corresponding to zone-folded phonons, appear in the Raman spectrum. The zone-folding mechanism in CuO is unusual in that one of the folded phonons hardens significantly in frequency as the sample is further cooled below TN2. It is shown that this dependence on temperature is determined by the sublattice magnetization and that the unusually large shift in frequency is caused by a strong spin-phonon interaction in cupric oxide.
    Chen, J., Deng, S.Z., Xu, N.S., Zhang, W., Wen, X., and Yang, S.
    Temperature dependence of field emission from cupric oxide nanobelt films 2003 Applied Physics Letters
    Vol. 83, pp. 746-748 
    article DOI  
    Abstract: Films of aligned cupric oxide nanobelts have been prepared in an aqueous solution at room temperature. Field-emission characteristics, including emission-current-applied-field plot and emission site distribution, have been studied using the transparent anode technique. In addition, the temperature dependence of the field-emission characteristics has been studied from room temperature to 750 K. The threshold field for obtaining a current density of 10 μA/cm2 is ~11 MV/m. This decreases with increasing temperature, and at 700 K it is ~6 MV/m. At a fixed field of 10 MV/m, about a three-orders-of-magnitude increase of the emission current level has been observed. The results show that the cupric oxide nanobelt is a promising candidate for cathode material in a thermoelectric conversion device based on field emission.
    Chen, A., Haddad, S., Wu, Y.-C. (J., Fang, T.-N., Lan, Z., Avanzino, S., Pangrle, S., Buynoski, M., Rathor, M., Cai, W. (D., Tripsas, N., Bill, C., VanBuskirk, M., and Taguchi, M.
    Non-Volatile Resistive Switching for Advanced Memory Applications 2005 IEEE International Electron Devices Meeting, 2005. IEDM Technical Digest, pp. 746-749  inproceedings DOI  
    Chen, A., Haddad, S., and Fang, T.-N.
    Resistive memory device with improved data retention and reduced power 2006 (US2006/0256608A1)  patent  
    Chen, A., Haddad, S., Wu, Y.C., Lan, Z., Fang, T.N., and Kaza, S.
    Switching characteristics of Cu2O metal-insulator-metal resistive memory 2007 Applied Physics Letters
    Vol. 91, pp. 123517 
    article DOI  
    Chen, Q., Shen, X., and Gao, H.
    Formation of solid and hollow cuprous oxide nanocubes in water-in-oil microemulsions controlled by the yield of hydrated electrons 2007 Journal of Colloid and Interface Science
    Vol. 312(2), pp. 272-278 
    article DOI  
    Abstract: A local ordered structure constructed from solid Cu2O nanocubes was obtained by the radiolytic reduction of Cu(NO3)2 in a water-in-oil (W/O) microemulsion composed of Triton X-100, n-hexanol, cyclohexane, and water in the presence of ethylene glycol (EG). However, when Triton X-100 was replaced with Brij 56 in the microemulsion, hollow Cu2O nanocubes were synthesized. The addition of toluene into the Brij 56 system could decrease the ratio of hollow nanocubes. It was suggested that the balance between the reduction rate of Cu2+ depending on the yield of hydrated electrons (e-aq) and the escape rate of the mixed solvent determined their final morphologies. The presence of EG influenced the rigidity of the interface of the microemulsion and thus the above balance, which resulted in the different morphologies of Cu2O nanoparticles in the Brij 56-based microemulsion.
    Chen, J.-Y., Zhou, P.-J., Li, J.-L., and Wang, Y.
    Studies on the photocatalytic performance of cuprous oxide/chitosan nanocomposites activated by visible light 2008 Carbohydrate Polymers
    Vol. 72(1), pp. 128-132 
    article DOI  
    Abstract: Taking the chitosan nanoparticles prepared by adding only sodium sulfate into acetic acid solution of chitosan as carriers, cuprous oxide/chitosan nanocomposites were prepared by electrochemical deposition. It's found that the needle shaped cuprous oxide nanocrystallines are combined with chitosan particles by chelation. Activated by a visible light, Cu2O/chitosan nanocomposites are used as a photocatalyst in the degradation of brilliant red X-3B of which the initial concentration is set as 50 mg/L. The results show that the best efficiency was obtained when the mass ratio of Cu2O in Cu2O/chitosan nanocomposites was 50%. And after the photocatalytic reaction, the residual copper element concentration can be cut down from 1.545 mg L-1 to 0.337 mg L-1 which is up to the drinking water standard of WHO.
    Chen, C., He, L., Lai, L., Zhang, H., Lu, J., Guo, L., and Li, Y.
    Magnetic properties of undoped Cu2O fine powders with magnetic impurities and/or cation vacancies 2009 Journal of Physics: Condensed Matter
    Vol. 21(14), pp. 145601 
    article DOI  
    Abstract: Fine powders of micron- and submicron-sized particles of undoped Cu2O semiconductor, with three different sizes and morphologies, have been synthesized by different chemical processes. These samples include nanospheres 200 nm in diameter, octahedra of size 1 µm and polyhedra of size 800 nm. They exhibit a wide spectrum of magnetic properties. At low temperature, T = 5 K, the octahedron sample is diamagnetic with the magnetic susceptibility χOH = -9.5 × 10-6 emu g-1 Oe-1. The nanosphere is paramagnetic with χNS = 2.2 × 10‑5 emu g‑1 Oe‑1. The other two polyhedron samples synthesized in different runs by the same process are found to show different magnetic properties. One of them exhibits weak ferromagnetism with TC~455 K and saturation magnetization MS~0.19 emu g‑1 at T = 5 K, while the other is paramagnetic with χ = 1.0 × 10‑5 emu g‑1 Oe‑1. The total magnetic moment estimated from the detected impurity concentration of Fe, Co and Ni, is too small to account for the observed magnetism by one to two orders of magnitude. Calculations by density functional theory (DFT) reveal that cation vacancies in the Cu2O lattice are one of the possible causes of induced magnetic moments. The results further predict that the defect-induced magnetic moments favour a ferromagnetically coupled ground state if the local concentration of cation vacancies, nC, exceeds 12.5%. This offers a possible scenario to explain the observed magnetic properties. The limitations of the investigations in the present work, in particular in the theoretical calculations, are discussed and possible areas for further study are suggested.
    Chen, D., Ni, S., Fang, J., and Xiao, T.
    Preparation of Cu2O nanoparticles in cupric chloride solutions with a simple mechanochemical approach 2010 Journal of Alloys and Compounds
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: The cuprous oxide (Cu2O) nanoparticles with diameter of 50-150�nm are prepared by high-energy ball milling in the various CuCl2 solutions with different [Cl-] concentration. The as-synthesized products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Finally, the effects of [Cl-] concentrations on the formation of cuprous oxide and reaction mechanism are discussed.
    Chen, Y., Yan, H., Yang, B., Lv, Y., Wen, M., Xu, J., Wu, M., Zhu, X., and Fu, Z.
    Fabrication and optical properties of Cu2O--ZnO composite opal 2010 Applied Physics A: Materials Science & Processing
    Vol. 98(2), pp. 467-472 
    article DOI  
    Abstract: Abstract  Cu2O–ZnO composite opal was fabricated by electrodeposition using ZnO inverse opal as template. The photonic stop band of the composite opal can be observed from the UV–Vis spectrum, which indicates that the Cu2O filled into ZnO inverse opal did not destroy its three-dimensional (3D) ordered structure. Due to the multiple scattering in the 3D ordered structure, the absorption and photoluminescence (PL) are stronger in Cu2O–ZnO composite opal than those in a Cu2O/ZnO bilayer film and a Cu2O/ITO film without 3D ordered structure. The remaining ZnO inverse opal in Cu2O–ZnO composite opal enhances the photoluminescence measured in back geometry while it suppresses that in front geometry.
    Cherevko, S. and Chung, C.-H.
    The porous CuO electrode fabricated by hydrogen bubble evolution and its application to highly sensitive non-enzymatic glucose detection 2010 Talanta
    Vol. 80(3), pp. 1371-1377 
    article DOI  
    Abstract: The porous Cu film was deposited on a Pt/Ti/Si substrate by electrochemical deposition accompanied by hydrogen evolution at very high current densities. CuO films with similar morphologies were obtained by subsequent annealing of the porous copper films. The morphology, composition and structure of the porous Cu and porous CuO were investigated by FE-SEM, EDS and XRD methods. The complete transformation of Cu to CuO after annealing was indicated. The sensing performances of the porous CuO film were evaluated in alkaline solution with the porous CuO film showing a wide linearity range from 1�[mu]M to 2.5�mM with sensitivity of 2.9�mA�cm-2�mM-1, and detection limit of 0.14�[mu]M. The sensor showed good selectivity to conventional intermediates such as AA and UA and long term stability.
    Ching, W.Y., Xu, Y.-N., and Wong, K.W.
    Ground-state and optical properties of Cu2O and CuO crystals 1989 Physical Review B
    Vol. 40(11), pp. 7684-7695 
    article DOI  
    Chou, M.H., Liu, S.B., Huang, C.Y., Wu, S.Y., and Cheng, C.-L.
    Confocal Raman spectroscopic mapping studies on a single CuO nanowire 2008 Applied Surface Science
    Vol. 254, pp. 7539-7543 
    article DOI  
    Abstract: In this study we are able, using a copper grid substrate, to successfully grow separate nanowires with a high level of crystallinity, for a length of
    up to 10 mm. They were synthesized under various temperatures.We compare and contrast three types of geometries (micron-, nano-scale, and tip-
    like single CuO nanowires), to identify their potential for monitoring the size effects of quantum confinements. The confocal Raman spectrometry
    results confirm the expected outcome, that reducing of the diameter of a cylindrical cross-section of a single nanowire results in Raman frequency
    downshifts. The results can be explained by the bond polarizability model. The applicability of investigating the size effects of the quantum
    confinement of the tip-like geometry of a single nanowire without any preparation for different sizes of nanoparticles is possible because the
    detection is relatively straightforward and the reproduced Raman signals can be observed.
    Chrzanowski, J. and Irwin, J.C.
    Raman scattering from cupric oxide 1989 Solid State Communications
    Vol. 70(1), pp. 11-14 
    article DOI  
    Abstract: Raman scattering experiments have been carried out on Cupric Oxide (CuO) throughout the temperature range from 15K to 300K. The three Raman active modes predicted by group theory have been identified and their room temperature frequencies determined to be 298, 345 and 632 cm-1. A new mode appears in the spectra (240 cm-1 at 15K) as the sample is cooled below the N�el Temperature (TN = 225� 5K of CuO. Based upon its temperature dependence this mode is tentatively assigned to scattering from a low-lying electronic excitation. Another mode (218 cm-1 at 300K) softens and disappears on cooling the sample below 200K. The results are discussed in terms of data obtained from recent neutron and Mossbauer studies on CuO.
    Clarke, E. and Czanderna, A.W.
    Optical transmittance and microgravimetric studies of the oxidation of $langle 100 single crystal films of copper 1975 Surface Science
    Vol. 49, pp. 529-536 
    article DOI  
    Abstract: Not Available
    Clavaguera-Mora, M.T., Touron, J.L., Rodríguez-Viejo, J., and Clavaguera, N.
    Thermodynamic description of the Cu--O system 2004 Journal of Alloys and Compounds
    Vol. 377, pp. 8-16 
    article DOI  
    Colacino, E., Villebrun, L., Martinez, J., and Lamaty, F.
    PEG$_3400$--Cu2O--Cs2CO$_3$: an efficient and recyclable microwave-enhanced catalytic system for ligand-free Ullmann arylation of indole and benzimidazole 2010 Tetrahedron
    Vol. 66(21), pp. 3730-3735 
    article DOI  
    Abstract: A mild, simple and efficient microwave-enhanced copper-catalyzed protocol for N-arylation using high molecular weight poly(ethylene glycol) (PEG3400) as a solvent is reported. Indole and benzimidazole have been N-arylated in the presence of cuprous oxide, cesium carbonate, and PEG3400, under microwave activation, with no supplementary ligands. Simple treatment by precipitation in Et2O and filtration provided the expected product after evaporation and recovery of the catalytic system as a precipitate. The recovery and one successful re-use of the catalytic system is also described. The formation of copper-based nanoparticles was demonstrated by TEM analysis.
    Compaan, A. and Cummins, H.Z.
    Raman Scattering, Luminescence, and Exciton-Phonon Coupling in Cu2O 1972 Physical Review B
    Vol. 6, pp. 4753-4757 
    article DOI  
    Compaan, A. and Cummins, H.Z.
    Resonant Quadrupole-Dipole Raman Scattering at the $1S$ Yellow Exciton in Cu2O 1973 Physical Review Letters
    Vol. 31(1), pp. 41-44 
    article DOI  
    Condorelli, G.G., Malandrino, G., and Fragalà, I.
    Metal-Organic Chemical Vapor Deposition of Copper-Containing Phases: Kinetics and Reaction Mechanisms 1994 Chemistry of Materials
    Vol. 6(10), pp. 1861-1866 
    article DOI  
    Condorelli, G.G., Malandrino, G., and Fragalà, I.L.
    Kinetic Study of MOCVD Fabrication of Copper(I) and Copper(II) Oxide Films 1999 Chemical Vapor Deposition
    Vol. 5(1), pp. 21-27 
    article DOI  
    Condorelli, G.G., Malandrino, G., and Fragalà, I.L.
    Nucleation and Growth of Copper Oxide Films in MOCVD Processes Using the $-Ketoiminate Precursor $4,4$'-($1,2$-Ethanediyldinitrilo)bis($2$-pentanonate) Copper(II) 1999 Chemical Vapor Deposition
    Vol. 5(5), pp. 237-244 
    article DOI  
    Coret, A. and Nikitine, S.
    Étude et interprétation du spectre de photoconductivité de la cuprite 1963 Journal de Physique
    Vol. 24(8), pp. 581-586 
    article DOI  
    Abstract: The photoconductivity of Cu2O at 77 °K has been studied as a function of the wave length of the light. The different series of exciton absorption lines appear in the photoconductivity response curve. However the lines can appear as maxima or as minima of the photoconductivity according to the conditions under which the experiment is carried out. Different properties of the photoconductivity are studied. In particular, a negative effect can be observed with Cu2O. The conditions underwhich these effects are observed have been determined. It is shown that these effects are observed when traps of a special kind are present on the surface of the crystal and on the boundary between grains.
    Czanderna, A.W.
    Magnetic Susceptibility of Cuprous Oxide Single Crystals at $25^rcC$ 1966 The Journal of Chemical Physics
    Vol. 45(8), pp. 3159-3160 
    article DOI  
    Dahl, J.P. and Switendick, A.C.
    Energy bands in cuprous oxide 1966 Journal of Physics and Chemistry of Solids
    Vol. 27, pp. 931-942 
    article DOI  
    Abstract: Not Available
    Dahl, J.P.
    THE BAND STRUCTURE OF CUPROUS OXIDE 1967 Journal de Physique Colloques
    Vol. 28, pp. C3-31-C3-31 
    article DOI  
    Daltin, A.-L., Addad, A., and Chopart, J.-P.
    Potentiostatic deposition and characterization of cuprous oxide films and nanowires 2005 Journal of Crystal Growth
    Vol. 282, pp. 414-420 
    article DOI  
    Abstract: Potentiostatic deposition of cuprous oxide (Cu2O) nanowires in polycarbonate membrane by cathodic reduction of alkaline cupric lactate solution has been investigated. These nanowires, characterized by scanning electron microscopy, have uniform diameters of about 100 nm and lengths up to 16 μm. The electrochemical quartz crystal microbalance (EQCM) is used for in situ phase analysis measurements of the thin films, and the phase composition is determined by X-ray diffraction analysis. The electrochemical parameter limits for the deposition of nanowires are reported. The nanowires have been confirmed as crystalline Cu2O by powder X-ray diffraction, electronic nanodiffraction and energy dispersive X-ray spectroscopy.
    Daltin, A.-L., Bohr, F., and Chopart, J.-P.
    Kinetics of Cu2O electrocrystallization under magnetic fields 2009 Electrochimica Acta
    Vol. 54(24), pp. 5813-5817 
    article DOI  
    Abstract: The magnetic field effects on cuprous oxide cathodic electrodeposition from alkaline cupric lactate solution have been investigated at 70��C by electrochemical and physical techniques. Stationary analyses exhibit a tenuous decrease of the plateau electrolytic current as the magnetic field increases. Due to the limited diffusion process of the hydroxide species which reacts during the electrochemical process, a magnetically induced effect can be suspected but deposition of Cu2O that covers the electrode and "passivates" the surface leads to antagonist effects that explain the current decrease. For a cathodic applied potential corresponding to the current plateau, X-ray diffraction studies reveal the formation of single phase cubic Cu2O films with or without magnetic field, but a change in electrocrystallization kinetics of Cu2O is observed in the presence of the magnetic field. Analyses of the transient current curves reveal a convective effect of the magnetic field from the very first moments of the electrocrystallization.
    Dasbach, G., Fröhlich, D., Stolz, H., Klieber, R., Suter, D., and Bayer, M.
    Wave-Vector-Dependent Exciton Exchange Interaction 2003 Physical Review Letters
    Vol. 91(10), pp. 107401 
    article DOI  
    Abstract: The exchange interaction for the yellow 1S orthoexciton in Cu2O is derived up to the order K2. The resulting exchange splittings are verified experimentally using high resolution spectroscopy. In agreement with theory the fine structure shows a characteristic dependence on the direction of the wave vector.
    Dasbach, G., Fröhlich, D., Stolz, H., Klieber, R., Suter, D., and Bayer, M.
    $K$-dependent exchange interaction of quadrupole excitons in Cu2O 2003 Physica Status Solidi (b)
    Vol. 238(3), pp. 541-547 
    article DOI  
    Dasbach, G.
    Spectroscopy of Polaritonic Excitations in Semiconductors 2003 School: Dortmund University, Shaker, Aachen  phdthesis URL 
    Dasbach, G., Fröhlich, D., Klieber, R., Suter, D., Bayer, M., and Stolz, H.
    Wave-vector-dependent exchange interaction and its relevance for the effective exciton mass in Cu2O 2004 Physical Review B
    Vol. 70(4), pp. 045206 
    article DOI  
    Abstract: The wave-vector dependence of electron-hole exchange interaction is investigated. For the yellow 1S exciton in Cu2O the exchange is derived up to the order k2 . The theoretical predictions are verified experimentally by high-resolution absorption experiments. In agreement with theory the fine structure shows a characteristic dependence on the direction of the wave vector. The exchange splitting of the orthoexciton triplet are distinguished from strain-induced perturbations. The exchange gives rise to an isotropic and an anisotropic correction of the effective exciton mass. This can explain the discrepancies in the measurements of the exciton mass in Cu2O .
    Dasbach, G., Fröhlich, D., Stolz, H., Klieber, R., Suter, D., and Bayer, M.
    Anisotropic effective exciton mass in Cu2O 2005 Physica Status Solidi (c)
    Vol. 2, pp. 886-889 
    article DOI  
    Dash, L., Bruneval, F., Trinité, V., Vast, N., and Reining, L.
    Electronic excitations: Ab initio calculations of electronic spectra and application to zirconia ZrO2, titania TiO2 and cuprous oxide Cu2O 2007 Computational Materials ScienceSelected papers from the International Conference on Computational Methods in Sciences and Engineering 2004 - ICCMSE-2004, International Conference on Computational Methods in Sciences and Engineering 2004
    Vol. 38(3), pp. 482-493 
    article DOI  
    Daunois, A., Deiss, J.L., and Meyer, B.
    Étude spectrophotométrique de l'absorption bleue et violette de Cu2O 1966 Journal de Physique
    Vol. 27, pp. 142-146 
    article DOI  
    Daunois, A. and Deiss, J.L.
    Vol. 35, pp. C3-53-C3-66 
    article DOI  
    Dawson, P., Hargreave, M.M., and Wilkinson, G.R.
    The dielectric and lattice vibrational spectrum of Cuprous Oxide 1973 Journal of Physics and Chemistry of Solids
    Vol. 34, pp. 2201-2208 
    article DOI  
    Deiss, J.L., Grun, J.B., and Nikitine, S.
    Observation de deux raies faibles nouvelles dans le spectre de la cuprite à $4,2^rcK$. Essai d'interprétation 1963 Journal de Physique
    Vol. 24(3), pp. 206-208 
    article DOI  
    Abstract: wo new lines have been observed in the spectrum of cuprous oxide (Cu 2O). The lines are very weak and situated in the spectrum at : λ 1 = 5 798 Å, λ2 = 5 829 Å. Some evidence has been obtained in favour of the interpretation of the λ1 line as a forbidden transition towards the exciton level 2S of the yellow series. It is suggested that the λ2 line corresponds to a forbidden transition towards the state n = 1 of the green series.
    Deiss, J.L., Daunois, A., and Nikitine, S.
    Electroabsorption in the yellow exciton series of Cu2O 1969 Solid State Communications
    Vol. 7(19), pp. 1417-1419 
    article DOI  
    Deiss, J.L., Daunois, A., and Nikitine, S.
    Influence of an electric field on the quadrupole line of Cu2O 1970 Solid State Communications
    Vol. 8(7), pp. 521-525 
    article DOI  
    Abstract: The effect of an electric field on the 1S quadrupole line of the yellow series of Cu2O has been studied with oriented single crystals, using conventional and modulation techniques. An [`]ignition' of the quadrupole line under the action of the electric field has been observed as well as an anisotropy of this effect. The line is also shifted to lower energies under the action of the electric field. Therefore signals due to indirect phonon transitions are detected in the modulation technique.
    Deiss, J.L., Daunois, A., and Nikitine, S.
    Electroabsorption near the $n = 1$ lines of the yellow and green series of Cu2O 1971 Physica Status Solidi (b)
    Vol. 47(1), pp. 185-192 
    article DOI  
    Abstract: The effect of an ac electric field on the n = 1 lines of the yellow and green series of Cu2O has been studied at 4.2�K using single crystals, polarized light, and a modulation technique. In the field, an ldquoignitionrdquo of the two lines lambda1Sy = 6098 � and lambda1Sg = 5830 � is observed. This ignition effect depends on the geometry of the experiment, and gives information on the nature of both transitions as well as on the bands involved in the formation of these IS excitons. The line lambda1Sg corresponds to an orthoexcitonic electric quadrupole transition Gamma25+, while the line lambda1Sg is a mixed electric quadrupole Gamma12+ and magnetic dipole Gamma15+ transition, with a stronger magnetic dipole character.
    Deiss, J.L., Daunois, A., and Nikitine, S.
    Electroabsorption near the $1S$ line of the green series of Cu2O 1971 Solid State Communications
    Vol. 9(3), pp. 217-221 
    article DOI  
    Abstract: The effect of an electric field on the n = 1 line of the green series of Cu2O has been studies at 4.2�K, using single crystals, polarized light and a modulation technique. Under the action of an electric field, an ignition of this line ([lambda]g1S = 5 830 �) is observed. This ignition effect depends on the geometry of the experiments, and gives informations on the nature of this transition as well as on the bands involved in the formation of this exciton.
    Deiss, J. and Daunois, A.
    Modulated exciton spectroscopy 1973 Surface Science
    Vol. 37, pp. 804-827 
    article DOI  
    de Jongh, P.E., Vanmaekelbergh, D., and Kelly, J.J.
    Cu2O: a catalyst for the photochemical decomposition of water? 1999 Chemical Communications, pp. 1069-1070  article DOI  
    Delatorre, R.G., Munford, M.L., Zandonay, R., Zoldan, V.C., Pasa, A.A., Schwarzacher, W., Meruvia, M.S., and Hümmelgen, I.A.
    $p$-type metal-base transistor 2006 Applied Physics Letters
    Vol. 88(23), pp. 233504 
    article DOI  
    Dellacherie, J., Balesdent, D., and Rilling, J.
    Ionic Conductivity of Cuprous Oxide as a Function of its Composition to $400^rc$C 1970 Journal de Chimie Physique et de Physico-Chimie Biologique
    Vol. 67, pp. 360-367 
    Dellacherie, J. and Balesdent, D.
    Conductivite Electrique Totale Du Protoxyde De Cuivre En Fonction De Sa Composition Define Par Des Electrodes 1976 Journal of Physics and Chemistry of Solids
    Vol. 37, pp. 539-548 
    article DOI  
    Denev, S. and Snoke, D.W.
    Stress dependence of exciton relaxation processes in Cu2O 2002 Physical Review B
    Vol. 65(8), pp. 085211 
    article DOI  
    Abstract: A comprehensive study of the exciton relaxation processes in Cu2O has led to some surprises. We find that the ortho-para conversion rate becomes slower at high stress and that the Auger nonradiative recombination rate increases with stress, with apparently no Auger recombination at zero stress. These results have important consequences for the pursuit of Bose-Einstein condensation of excitons in a harmonic potential.
    Dieckmann, R.
    Point Defects and Diffusion in Nonstoichiometric Metal Oxides 1991 MRS Bulletin
    Vol. 16, pp. 27-32 
    article URL 
    Dieckmann, R.
    Point Defects and Transport of Matter and Charge in Non-Stoichiometric Oxides 1995 ``Crystal Growth of Novel Electronic Materials'', Ceramic Transactions
    Vol. 60, pp. 301-330 
    Dieckmann, R.
    Point Defects and Transport of Matter and Charge in Non-Stoichiometric Oxides (II) 1996 ``Mass and Charge Transport in Ceramics'', Ceramic Transactions
    Vol. 71, pp. 33-50 
    Dieckmann, R.
    Point Defects and Transport In Non-Stoichiometric Oxides: Solved and Unsolved Problems 1998 Journal of Physics and Chemistry of Solids
    Vol. 59, pp. 507-525 
    article DOI  
    Dimitriadis, C.A., Papadimitriou, L., and Economou, N.A.
    Resistivity dependence of the minority carrier diffusion length in single crystals of Cu2O 1983 Journal of Materials Science Letters
    Vol. 2, pp. 691-693 
    article DOI  
    Di Quarto, F., Piazza, S., and Sunseri, C.
    Photoelectrochemical study of the corrosion product layers on copper in weakly acidic solutions 1985 Electrochimica Acta
    Vol. 30(3), pp. 315-324 
    article DOI  
    Abstract: The nature of the surface layers grown on copper electrodes in free corrosion conditions in unbuffered aerated Na2SO4 solutions (pH = 3.0-6.0) was investigated by photoelectrochemical methods. The formation of cuprous oxide has been revealed by means of a careful study of the photocurrent spectra obtained in situ. The growth of n-Cu2O has been observed to occur with or without Cu2+ ions in solution in a narrow range of pH around five. More acidic solutions seem to favour the formation of p-Cu2O both in absence as well as in presence of Cu2+ ions in solution ([Cu2+] = 0.05 M). The addition of chloride ions in variable amounts ([Cl-] [less-than-or-equals, slant] 0.1 M) seems to affect mainly the corrosion rate of copper electrodes at low concentrations ([Cl-] [less-than-or-equals, slant] 10-2 M). At higher chloride concentrations changes in the semiconducting properties as well as in the nature of the corrosion layers can occur. The presence of complex transients in the photocurrent vs time plots has been related to the presence of chloride ions in solution.
    Dixit, K.R.
    Copper--Cuprous Oxide Rectifier 1945 Current Science
    Vol. 14, pp. 143-144 
    article URL 
    Dobrovol'skii, V.N. and Gritsenko, Y.I.
    Use of the Hall current for investigation of carrier scattering in semiconductors 1963 Soviet Physics - Solid State
    Vol. 4, pp. 2025-2031 
    Dodoo-Arhin, D., Leoni, M., Scardi, P., Garnier, E., and Mittiga, A.
    Synthesis, characterisation and stability of Cu2O nanoparticles produced via reverse micelles microemulsion 2010 Materials Chemistry and Physics
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: Cuprite (Cu2O) nanoparticles were synthesized at room temperature via reduction of CuCl2�2H2O by NaBH4 in water/n-heptane microemulsion stabilised by the non-ionic Brij30 surfactant. Whole Powder Pattern Modelling of the X-ray diffraction patterns shows the presence of a bimodal size distribution in the nanopowders, with a fraction of domains in the 10-40�nm range and a smaller one below 10�nm. Linear and planar defects are absent. A relationship between the average size of the larger particles and the quantity of water in the system was obtained. The stability of cuprite under visible light irradiation both during the synthesis and after the preparation was investigated, showing that a self-catalytic conversion of Cu2O into CuO takes place in water.
    Dominguez-Rodriguez, A. and Castaing, J.
    Point defect and diffusion properties in oxides from high temperature creep 1983 Radiation Effects and Defects in Solids
    Vol. 75(1), pp. 309-315 
    article DOI  
    Abstract: A study of high temperature creep properties of non-stoichiometric CU2O, CoO and NiO has been performed at various temperatures and oxygen activities (Po2). Creep rates are directly related to point defects responsible for the diffusion of the slowest species. These point defects have been tentatively identified by the Po2 dependence of creep rate which does not depend on the detailed mechanism of deformation.
    Douglas, B.E. and Ho, S.-M.
    ``Crystal Structures Involving P and T Layers'' in Structure and Chemistry of Crystalline Solids 2006 Ch. 6, pp. 117-146  inbook DOI  
    Drobny, V.F. and Pulfrey, D.L.
    The photovoltaic properties of thin copper oxide films 1978 Prooceeding of the 13th IEEE Photovoltaic Specialists Conference, pp. 180-183  inproceedings  
    Drobny, V.F. and Pulfrey, D.L.
    Vol. 61, pp. 89-98 
    article DOI  
    Du, Y., Zhang, N., and Wang, C.
    Photo-catalytic degradation of trifluralin by SnO2-doped Cu2O crystals 2010 Catalysis Communications
    Vol. 11(7), pp. 670-674 
    article DOI  
    Abstract: The SnO2-doped Cu2O has been produced in aqueous solution using hydrazine as the reducing agent. Techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy were used to comprehend the relation between structure and properties of the SnO2-doped Cu2O. The effects of SnO2 insertion on the Cu2O photo-catalytic activity for the degradation of trifluralin were reported here. The results show that SnO2-doping can greatly enhance catalytic activity of Cu2O nano-crystals.
    Du, L. and Wang, H.
    Infrared laser induced lateral photovoltaic effect observed in Cu2O nanoscale film 2010 Optics Express
    Vol. 18(9), pp. 9113-9118 
    article URL 
    Dubois, L.
    Oxygen chemisorption and cuprous oxide formation on Cu(111): A high resolution EELS study 1982 Surface Science
    Vol. 119(2-3), pp. 399-410 
    article DOI  
    Abstract: The interaction of oxygen with a Cu(111) single crystal surface was investigated using high resolution electron energy loss spectroscopy. Experiments were carried out at gas exposures ranging from 10 to 109L and at temperatures between 298 and 523 K. Three distinct stages of chemisorption/oxidation were distinguished by their vibrational spectra: (1) chemisorbed oxygen atoms either in or below the outermost plane of copper atoms, (2) Cu2O island formation most likely at defect sites on the surface, and (3) the growth of a bulk cuprous oxide thin film.
    Dünwald, H. and Wagner, C.
    Untersuchungen über Fehlordnungserscheinungen in Kupferoxydul und deren Eintluss auf die elektrischen Eigenschaften 1933 Zeitschrift für Physikalische Chemie B
    Vol. 22, pp. 212-225 
    Duvvury, C., Kenway, D.J., and Weichman, F.L.
    Excitation Characteristics of the IR Luminescence in Cu2O 1975 Journal of Luminescence
    Vol. 10, pp. 415-418 
    article DOI  
    Ebisuzaki, Y.
    Preparation of Monocrystalline Cuprous Oxide 1961 Journal of Applied Physics
    Vol. 32, pp. 2027-2028 
    article DOI  
    Elliott, R.J.
    Intensity of Optical Absorption by Excitons 1957 Physical Review
    Vol. 108, pp. 1384-1389 
    article DOI  
    Elliott, R.
    Symmetry of excitons in Cu2O 1961 Physical Review
    Vol. 124, pp. 340-345 
    article DOI  
    Elliott, R.J.
    Theory of the Exciton Spectra in Cu2O 1961 Proceedings of the International Conference on Semiconductor Physics (5th edition, Prague, 1960), pp. 408-410  inproceedings  
    Eskhult, J., Herranen, M., and Nyholm, L.
    On the origin of the spontaneous potential oscillations observed during galvanostatic deposition of layers of Cu and Cu2O
    2006 Journal of Electroanalytical Chemistry
    Vol. 594, pp. 35-49 
    article DOI  
    Espinos, J.P., Morales, J., Barranco, A., Caballero, A., Holgado, J.P., and Gonzalez-Elipe, A.R.
    Interface Effects for Cu, CuO, and Cu2O Deposited on SiO2 and ZrO2. XPS Determination of the Valence State of Copper in Cu/SiO2 and Cu/ZrO2 Catalysts 2002 The Journal of Physical Chemistry B
    Vol. 106(27), pp. 6921-6929 
    article DOI  
    Ettema, A.R. and Versluis, J.
    Dipole-allowed generation of the yellow-series excitons in Cu2O due to an applied electric field 2003 Physical Review B
    Vol. 68(23), pp. 235101 
    article DOI  
    Abstract: The electron bands of Cu2O near the band gap have been calculated for the undistorted cubic crystal with Oh symmetry and a tetragonally distorted case with C4v symmetry. The tetragonal structure has a distortion of the linear Cu crystal field that represents the structure of a polarized crystal in an electric field. The symmetry of the bands changes in such a way that the dipole forbidden transition of the yellow series excitons in the undistorted cubic structure becomes dipole allowed in the tetragonal structure. The energy of the excitons becomes lower in the polarized crystal. These changes in the band gap properties make it possible to create an exciton trap in thin Cu2O films with a scanning tunneling microscopy tip while the excitons can be resonantly created with a laser via a dipole allowed transition.
    Evans, U.R. and Miley, H.A.
    Measurements of Oxide Films on Copper and Iron 1937 Nature
    Vol. 139, pp. 283 
    article DOI  
    Abstract: RECENT letters from Dobinski1 and Nelson2 report the rapid appearance of oxide upon unheated copper and iron on exposure to air. This oxide, which doubtless causes the rapid change in the behaviour of these metals to silver and copper nitrates respectively3, can be estimated by measuring the number of millicoulombs needed for its cathodic reduction. The principle was formerly used to measure silver iodide films4, and gave numbers agreeing with both gravimetric and iodometric methods. For oxide films it has yielded results in reasonable accord with optical5 and gravimetric methods (see accompanying table), and consistent with early chemical determinations made on the films after stripping6. Former disagreement between gravimetric and optical methods has been largely due to neglect of invisible films, or to different meanings attached to the term `thickness' as applied to a non-uniform film on an uneven surface.
    Fan, H.Y.
    Theory of Rectification of an Insulating Layer 1948 Physical Review
    Vol. 74(10), pp. 1505-1513 
    article DOI  
    Fan, H., Zou, B., Liu, Y., and Xie, S.
    Size effect on the electron phonon coupling in CuO nanocrystals 2006 Nanotechnology
    Vol. 17, pp. 1099-1103 
    article DOI  
    Abstract: CuO is the prototype compound of cuprate superconductors, so understanding its electronic structures will facilitate the study of the pairing mechanism and miscellaneous states of high-temperature superconductors. We prepared uniform CuO nanocrystals (7-100 nm) and studied their size-dependent Raman scattering spectra. The relative variation between the two-phonon scattering band (2Bg) and the one-phonon band (Bg) indicates a decreasing electron-phonon coupling with reducing size, which unveils the dominant Fröhlich electron-phonon coupling, as indicated by Devreese, but not the small polaron in CuO. Moreover, the anomalous enhancement of the multi-phonon band at a critical size and 1D structure at room temperature is attributable to an enhanced electron-phonon coupling accompanied by phonon-plasmon coupling, i.e., the 'plasphon' proposed by Alexandrov et al in 1981.
    Feldman, W.
    The Electrical Conductivity and Isothermal Hall Effect in Cuprous Oxide 1943 Physical Review
    Vol. 64, pp. 113-118 
    article DOI  
    Feng, Z., Marks, C.R., and Barkatt, A.
    Oxidation-Rate Excursions During the Oxidation of Copper in Gaseous Environments at Moderate Temperatures 2003 Oxidation of Metals
    Vol. 60(5), pp. 393-408 
    article DOI  
    Abstract: The kinetics of oxidation of copper powders in oxygen and in dry and humid air was investigated using thermogravimetric analysis (TGA). The extent of oxidation grew linearly with time until the weight-based thickness of the oxide film reached 0.13–1.22 nm, depending on the temperature. Between 30 and 90°C there was little difference between the kinetic curves observed in air and in oxygen, respectively. Higher humidity of the air resulted in an increased oxidation rate. Following the initial linear segment, the oxidation kinetics could be best described in terms of a logarithmic rate law between 30 and 45°C and in terms of a power law between 60 and 90°C. The activation energy for the initial linear stage was (44±2) kJ and for the subsequent oxidation (102±12) kJ. Delayed increases in oxidation rate were observed with a ca. 0.1-µm powder around 100°C, with a ca. 1-µm powder around 320°C, and with a < 10µm powder around 360°C. A three-stage model consisting of an initial linear stage, parabolic growth culminating in cracking of the oxide film, and subsequent re-start of the parabolic growth, gave good agreement with the experimental data. Whenever the powder is relatively uniform and the distribution of film-cracking times among the powder grains is narrow, e.g., within 23% of the median cracking time, an increase in the oxidation rate of the entire sample can be observed.
    Feng, H.-P., Lin, J.-Y., Wang, Y.-Y., and Wan, C.-C.
    Effect of Impurity and Illumination on Copper Oxidation after Chemical Mechanical Polishing 2008 Journal of the Electrochemical Society
    Vol. 155(8), pp. H620-H624 
    article DOI  
    Fernando, C.A.N. and Wetthasinghe, S.K.
    Investigation of photoelectrochemical characteristics of n-type Cu2O films 2000 Solar Energy Materials and Solar Cells
    Vol. 63(3), pp. 299-308 
    article DOI  
    Fernando, C.A.N., Bandara, T.M.W.J., and Wethasingha, S.K.
    H2 evolution from a photoelectrochemical cell with n-Cu2O photoelectrode under visible light irradiation 2001 Solar Energy Materials and Solar Cells
    Vol. 70(2), pp. 121-129 
    article DOI  
    Fernando, C.A.N., De Silva, L.A.A., Mehra, R.M., and Takahashi, K.
    Junction effects of p-Cu2O photocathode with layers of hole transfer sites (Au) and electron transfer sites (NiO) at the electrolyte interface 2001 Semiconductor Science and Technology
    Vol. 16(6), pp. 433-439 
    article DOI  
    Abstract: A well cleaned copper plate with a thin Au layer deposited was heated in air to make hole transfer sites with p-Cu 2 O at 800 °C for 3 min. A transparent NiO layer was prepared on the surface of this device to make electron transfer sites on the surface. This heat-treated device, having 2 µm Au layers, exhibited a remarkably stable steady photocurrent and a higher photocurrent quantum efficiency in a KI(10 -2 M) + I 2 (10 -4 M) electrolyte solution when a thin transparent 0.05 µm NiO layer was deposited on the surface to screen the electrolyte. During the heating of the Au-deposited copper plate at 800 °C for 3 min, initially an alloy of Cu and Au was produced, then a thin homogeneous p-Cu 2 O film was formed on the alloy by oxidizing the migrated Cu atoms onto the upper surface of the alloy. Characteristics of the samples observed by means of XRD measurements and SEM micrographs, V - I characteristics, photocurrent action spectra, the variations of the photocurrent quantum efficiency with the deposited thickness of NiO and Au layers, photodegradation and improved chemical stability of the p-Cu 2 O photocathode and H 2 evolution from water by the photocathode were investigated to explain the junction effects of the modified p-Cu 2 O with the Cu + Au alloy and NiO transparent film at the electrolyte interface. Here, the NiO layer and Au particles in the Au + Cu alloy efficiently act as the electron-transfer and hole-transfer sites, respectively.
    Fernando, C.A.N., de Silva, P.H.C., Wethasinha, S.K., Dharmadasa, I.M., Delsol, T., and Simmonds, M.C.
    Investigation of n-type Cu2O layers prepared by a low cost chemical method for use in photo-voltaic thin film solar cells 2002 Renewable Energy
    Vol. 26(4), pp. 521-529 
    article DOI  
    Fetisov, A. and Kuznetsov, M.
    X-ray photoelectron spectroscopy analysis of electronic states in the oxide layer on an ultradisperse copper surface 2009 Journal of Applied Spectroscopy
    Vol. 76(4), pp. 523-527 
    article DOI  
    Abstract: X-ray photoelectron spectroscopy (XPS) is used to study the electronic states of copper oxide covering a thin (2.0 ± 0.5 nm) layer of ultradisperse copper. A reduction in the thickness of the CuO layer is found to cause extremal behavior in the XPS spectrum parameters as opposed to their monontonic variations for CuO nanoparticles. This behavior is explained by the competition of two factors which affect the system under study: the dimensions of the substrate material and the electrostatic field in
    Fickelscher, H. and Zukale, W.
    Ultrarotabsorption des Kupferoxyduls (Cu2O) 1961 Naturwissenschaften
    Vol. 48(1), pp. 24-24 
    article DOI  
    Figueiredo, V., Elangovan, E., Gonçalves, G., Barquinha, P., Pereira, L., Franco, N., Alves, E., Martins, R., and Fortunato, E.
    Effect of post-annealing on the properties of copper oxide thin films obtained from the oxidation of evaporated metallic copper 2008 Applied Surface Science
    Vol. 254(13), pp. 3949-3954 
    article DOI  
    Figueiredo, V., Elangovan, E., Gonçalves, G., Franco, N., Alves, E., Park, S.H.K., Martins, R., and Fortunato, E.
    Electrical, structural and optical characterization of copper oxide thin films as a function of post annealing temperature 2009 Physica Status Solidi (a)
    Vol. 206(9), pp. 2143-2148 
    article DOI  
    Abstract: Copper oxide thin films were obtained by annealing (temperature ranging between 100 and 450��C) the metallic Cu films deposited on glass substrates by e-beam evaporation. XRD studies confirmed that the cubic Cu phase of the as-deposited films changes into single cubic Cu2O phase and single monoclinic CuO phase, depending on the annealing conditions. The crystallite size is varied between sim12 and 31�nm. The lattice parameters of cubic Cu and Cu2O phases are estimated to sim3.60 and sim4.26��, respectively. The films with Cu2O phase showed p-type characteristics. The conductivity is decreased linearly with the decreasing temperature (1/T), which has confirmed the semiconductor nature of the deposited films. The calculated activation energy is varied between 0.10 and 0.16�eV. The surface microstructure is changed depending on the variation in the annealing temperature. The poor transmittance of the as-deposited films (&lt;1%) is increased to a maximum of sim80% (800�nm) on annealing at 200��C. The estimated direct allowed band gap is varied between 1.73 and 2.89�eV.
    Fishman, D.A., Revcolevschi, A., and van Loosdrecht, P.H.M.
    Exciton dynamics in cuprous oxide 2006 Physica Status Solidi (c)
    Vol. 3, pp. 2469-2472 
    article DOI  
    Abstract: This work addresses the mid-infrared properties of cuprous oxide and in particular induced absorption due to the presence of excitons. We probe the population of the non-radiative ground state of para-excitons via laser-induced changes of the transmission in the hydrogenic 1s-2p/1s-3p transition energy range in a stress-free sample.
    Fishman, D.
    Excitons in cuprous oxide 2008 School: Zernike Institute for Advanced Materials, University of Groningen  phdthesis URL 
    Fishman, D., Faugeras, C., Potemski, M., Revcolevschi, A., and van Loosdrecht, P.H.M.
    Magneto-optical readout of dark exciton distribution in cuprous oxide 2009 Physical Review B
    Vol. 80(4), pp. 045208 
    article DOI  
    Forman, R.A., Brower Jr., W.S., and Parker, H.S.
    Phonons and the green exciton series in cuprous oxide, Cu2O 1971 Physics Letters A
    Vol. 36(5), pp. 395-396 
    article DOI  
    Fortin, E. and Weichman, F.L.
    Photoconductivity in cuprous oxide single crystals 1962 Canadian Journal of Physics
    Vol. 40(12), pp. 1703-1713 
    article URL 
    Fortin, E. and Weichman, F.L.
    Vol. 44(7), pp. 1551-1561 
    article URL 
    Fortin, E., Zouaghi, M., and Zielinger, J.P.
    High Temperature Photoconductivity in Cu2O 1967 Physics Letters A
    Vol. 24, pp. 180-182 
    article DOI  
    Fortin, E., Rochon, P., and Zielinger, J.P.
    Photoconductivity and Photovoltaic Excitation Spectra and Their Wavelength Derivative in Cu2O 1975 Journal of Physics and Chemistry of Solids
    Vol. 36, pp. 1299-1306 
    article DOI  
    Fortin, E. and Masson, D.
    Photovoltaic effects in Cu2O--Cu solar cells grown by anodic oxidation 1982 Solid-State Electronics
    Vol. 25(4), pp. 281-283 
    article DOI  
    Fortin, E. and Sears, W.M.
    Thin-film Cu2O/Cu photovoltaic cells 1982 Canadian Journal of Physics
    Vol. 60(6), pp. 901-908 
    article URL 
    Abstract: Thin-film Cu2O/Cu Schottky barrier photovoltaic back cells are studied in view of their possible application as solar cells. Graphs are constructed showing the dependence of the oxide layer thickness (in the 3 – 50 μm range) on the oxidation parameters such as the temperature, oxygen pressure, and time of oxidation. The solar-cell parameters such as Voc, Vsc and the spectral response are in turn investigated as functions of the oxide layer thickness. The results indicate that cells of possible practical interest will have an oxide layer thickness of the order of 1 μm, grown at high temperature, high oxygen pressure for oxidation times of less than 1 s.
    Fortin, E. and Tsélépis, E.
    Exciton Diffusion in Thin Cu2O Films 1988 Thin Solid Films
    Vol. 164, pp. 289-293 
    article DOI  
    Fortin, E., Fafard, S., and Mysyrowicz, A.
    Exciton transport in Cu2O: Evidence for excitonic superfluidity? 1993 Physical Review Letters
    Vol. 70(25), pp. 3951-3954 
    article DOI  
    Fortin, E. and Mysyrowicz, A.
    Bose--Einstein condensation and superfluidity of excitons in Cu2O 2000 Journal of Luminescence
    Vol. 87-89, pp. 12-14 
    article DOI  
    Fortunato, E., Pereira, L., Barquinha, P., Ferreira, I., Prabakaran, R., Gonçalves, G., Gonçalves, A., and Martins, R.
    Oxide semiconductors: Order within the disorder 2009 Philosophical Magazine
    Vol. 89, pp. 2741-2758 
    article DOI  
    Abstract: The effect is considered of order and disorder on the electrical and optical performance of ionic oxide semiconductors used to produce optoelectronic devices such as p–n heterojunction solar cells and thin-film transistors (TFTs). The results obtained show that p-type c-Si/a-IZO/poly-ZGO solar cells exhibit efficiencies above 14% in device areas of about 2.34 cm2, whereas amorphous oxide TFTs based on the Ga–Zn–Sn–O system demonstrate superior performance to the polycrystalline ZnO TFTs, with ION/IOFF ratio exceeding 107, turn-on voltage below 1–2 V and saturation mobility above 25 cm2 V-1 s-1. In addition, preliminary data on a p-type oxide TFT based on the Zn–Cu–O system are presented.
    Franke, P. and Neuschütz, D.
    Cu--O 2005 Landolt-Börnstein
    Vol. IV/19b3 
    incollection DOI  
    Frerichs, R. and Handy, R.
    Electroluminescence in Cuprous Oxide 1959 Physical Review
    Vol. 113(5), pp. 1191-1199 
    article DOI  
    Frerichs, R. and Liberman, I.
    Surface Mobility of Copper Ions on Cuprous Oxide 1961 Physical Review
    Vol. 121(4), pp. 991-996 
    article DOI  
    Fröhlich, D., Kenklies, R., Uihlein, C., and Schwab, C.
    Assignment of the Even-Parity Excitons in Cu2O 1979 Physical Review Letters
    Vol. 43, pp. 1260-1263 
    article DOI  
    Fröhlich, D., Kulik, A., Uebbing, B., Mysyrowicz, A., Langer, V., Stolz, H., and von der Osten, W.
    Coherent propagation and quantum beats of quadrupole polaritons in Cu2O 1991 Physical Review Letters
    Vol. 67(17), pp. 2343-2346 
    article DOI  
    Fröhlich, D., Dasbach, G., Baldassarri Höger von Högersthal, G., Bayer, M., Klieber, R., Suter, D., and Stolz, H.
    High resolution spectroscopy of yellow 1S excitons in Cu2O 2005 Solid State Communications
    Vol. 134, pp. 139-142 
    article DOI  
    Abstract: The 1S ortho- and para-exciton of the yellow series in Cu2O are studied by high resolution spectroscopy. We observe that the 3-fold ortho-exciton (Γ5+-symmetry) is not degenerate. For a general k-direction there are three resonances with line width down to 1 μeV. The splitting is quantitatively explained by taking into account the long range and short range exchange interaction. The group velocity of the quadrupole polariton is directly determined with use of 20 ns pulses with still high spectral resolution (ΔE≈0.1 μeV). Group velocities down to 4×104 m/s are quantitatively described by a one-oscillator quadrupole polariton model. The para-exciton (Γ2+-symmetry) is seen in absorption in magnetic fields down to 1 T. In selected crystals it shows a line width of 0.2 μeV.
    Fromhold Jr., A.
    Kinetics of oxide film growth on metal crystals--II: Homogeneous field approximations 1963 Journal of Physics and Chemistry of Solids
    Vol. 24(11), pp. 1309-1323 
    article DOI  
    Fromhold Jr., A.T. and Cook, E.L.
    Kinetics of Oxide Film Growth on Metal Crystals: Electron Tunneling and Ionic Diffusion 1967 Physical Review
    Vol. 158(3), pp. 600-612 
    article DOI  
    Fromhold Jr., A.T. and Cook, E.L.
    Kinetics of Oxide Film Growth on Metal Crystals: Thermal Electron Emission and Ionic Diffusion 1967 Physical Review
    Vol. 163(3), pp. 650-664 
    article DOI  
    Fromhold Jr., A.T.
    Fundamental Theory of the Growth of Thick Oxide Films on Metals 1980 Journal of the Physical Society of Japan
    Vol. 48(6), pp. 2022-2030 
    article DOI  
    Fromhold Jr., A.T. and Anderson Jr., M.H.
    Oxidation Kinetics of Epitaxial $(100)$ Copper Films at $25^rcC$ and $50^rcC$ 2004 Oxidation of Metals
    Vol. 62(3), pp. 237-272 
    article DOI  
    Abstract: Very-thin-film kinetics data are presented for oxide growth on parent epitaxially formed (100) copper crystals at 25 and 50°C with different oxygen pressures in the range 0.01 torr to 170 torr. The results are interpreted in terms of the model based on electric-field driven ionic diffusion associated with the electrostatic-potential difference created by an electron-tunnel- current-virtual equilibrium.
    Fujinaka, M. and Berezin, A.A.
    Cuprous oxide--indium--tin oxide thin film photovoltaic cells 1983 Journal of Applied Physics
    Vol. 54(6), pp. 3582-3588 
    article DOI  
    Fujiwara, T., Nakaue, T., and Yoshimura, M.
    Direct fabrication and patterning of Cu2O film by local electrodeposition method 2004 Solid State IonicsFourteenth International Conference on Solid State Ionics
    Vol. 175(1-4), pp. 541-544 
    article DOI  
    Abstract: We have developed a direct patterning method to form Cu2O patterns onto substrates by an electrodeposition method with a glass capillary tube, including an electrolyte containing CuSO4 and chelating agent. Cu2O pattern on the titanium substrates was successfully fabricated at 60 �C. Furthermore, we found that the chelating agent, which has -CH(OH)COOH group, was effective to form crystalline Cu2O patterns.
    Gan, Z.H., Yu, G.Q., Tay, B.K., Tan, C.M., Zhao, Z.W., and Fu, Y.Q.
    Preparation and characterization of copper oxide thin films deposited by filtered cathodic vacuum arc 2004 Journal of Physics D Applied Physics
    Vol. 37, pp. 81-85 
    article DOI  
    Abstract: Copper oxide thin films deposited on Si (100) by a filtered cathodic vacuum arc with and without substrate bias have been studied by atomic force microscopy, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results show that the substrate bias significantly affects the surface morphology, crystalline phases and texture. In the film deposited without bias, two phases—cupric oxide (CuO) and cuprous oxide (Cu2O)—coexist as cross-evidenced by XRD, XPS and Raman analyses, whereas CuO is dominant concurrent with CuO (020) texture in the film deposited with bias. The film deposited with bias exhibits a more uniform and clearer surface morphology although both kinds of films are very smooth. Some explanations are given as well.
    Gaplevskaya, S.P., Ezhik, I.I., and Rvachev, A.L.
    1975 Soviet Physics -- Semiconductors
    Vol. 8, pp. 1041 
    Garlick, G.F.J. and Dumbleton, M.J.
    Phosphors Emitting Infra-Red Radiation 1954 Proceedings of the Physical Society. Section B
    Vol. 67(5), pp. 442-443 
    article DOI  
    Garrison, A.D.
    The Behavior of Cuprous Oxide Photovolatic Cells 1923 The Journal of Physical Chemistry
    Vol. 27(7), pp. 601-622 
    article DOI  
    Garrison, A.
    The Photo-chemical Properties of Cuprous Oxide 1924 The Journal of Physical Chemistry
    Vol. 28(3), pp. 279-284 
    article DOI  
    Garuthara, R. and Siripala, W.
    Photoluminescence characterization of polycrystalline n-type Cu2O films 2006 Journal of Luminescence
    Vol. 121, pp. 173-178 
    article DOI  
    Gastev, S.V., Kaplyanskii, A.A., and Sokolov, N.S.
    Relaxed Excitons In Cu2O 1982 Solid State Communications
    Vol. 42, pp. 389-391 
    article DOI  
    Georgieva, V. and Ristov, M.
    Electrodeposited cuprous oxide on indium tin oxide for solar applications 2002 Solar Energy Materials and Solar Cells
    Vol. 73(1), pp. 67-73 
    article DOI  
    Abstract: Semiconducting cuprous oxide films were prepared by electrodeposition onto commercial conducting glass coated with indium tin oxide deposited by spraying technique. The cuprous oxide (Cu2O) films were deposited using a galvanostatic method from an alkaline CuSO4 bath containing lactic acid and sodium hydroxide at a temperature of 60�C. The film's thickness was about 4-6�[mu]m. This paper includes discussion for Cu2O films fabrication, scanning electron microscopy and X-ray diffractometry studies, optical properties and experimental results of solar cells. The values of the open circuit voltage Voc of 340�mV and the short circuit current density Isc of 245�[mu]A/cm2 for ITO/Cu2O solar cell were obtained by depositing graphite paste on the rear of the Cu2O layer. It should be stressed that these cells exhibited photovoltaic properties after heat treatment of the films for 3�h at 130�C. An electrodeposited layer of Cu2O offers wider possibilites for application and production of low cost cells, both in metal-semiconductor and hetero-junction cell structures, hence the need to improve the photovoltaic properties of the cells.
    Ghijsen, J., Tjeng, L.H., van Elp, J., Eskes, H., Westerink, J., Sawatzky, G.A., and Czyzyk, M.T.
    Electronic structure of Cu2O and CuO 1988 Physical Review B
    Vol. 38(16), pp. 11322-11330 
    article DOI  
    Ghijsen, J., Tjeng, L.H., Eskes, H., Sawatzky, G.A., and Johnson, R.L.
    Resonant photoemission study of the electronic structure of CuO and Cu2O 1990 Physical Review B
    Vol. 42(4), pp. 2268-2274 
    article DOI  
    Ghosh, S., Avasthi, D.K., Shah, P., Ganesan, V., Gupta, A., Sarangi, D., Bhattacharya, R., and Assmann, W.
    Deposition of thin films of different oxides of copper by RF reactive sputtering and their characterization 2000 Vacuum
    Vol. 57, pp. 377-385 
    article DOI  
    Gil, Y., Umurhan, O., and Riess, I.
    Properties of solid state devices with mobile ionic defects. Part I: The effects of motion, space charge and contact potential in metalsemiconductormetal devices 2007 Solid State Ionics
    Vol. 178(1-2), pp. 1-12 
    article DOI  
    Abstract: The characteristics of solid state devices based on p-type semiconductors with mobile acceptors are discussed. The devices are basic ones of the form: metalsemiconductormetal. The metal electrodes are assumed to be chemically inert and to block material exchange. The effect of the contact potentials as well as of the space charge are taken into consideration. The distribution of charge carriers (holes and acceptors) and the I-V relations are evaluated. These results are compared with those of a model in which the acceptors are immobile and with two approximations in which neutrality is assumed either at the boundary or throughout the whole semiconductor. The motion of the acceptors is found, in some cases, to introduce only minor changes in the I-V relations. This finding may be of significance for solid state devices of reduced scale. The I-V relations of samples much thicker than the equilibrium Debye length reduce to the ones obtained assuming local neutrality throughout the sample. The results also depend significantly on the reaction constant between the acceptors and holes to form neutral acceptors.
    Gizhevskii, B.A., Sukhorukov, Y.P., Loshkareva, N.N., Moskvin, A.S., Zenkov, E.V., and Kozlov, E.A.
    Optical absorption spectra of nanocrystalline cupric oxide: possible effects of nanoscopic phase separation 2005 Journal of Physics: Condensed Matter
    Vol. 17(3), pp. 499 
    article DOI  
    Abstract: Optical absorption spectra of nanocrystalline cupric oxide CuO samples, obtained using the
    converging spherical shock wave procedure, reveal significant spectral weight red-shift as compared
    with spectra of single-crystalline CuO samples. In addition, some of these samples manifest
    remarkable temperature-dependent resonances near 1.3–1.6 eV. The minimal model suggested to explain
    both effects implies the CuO nanoceramic to be a metastable system of metallic-like nanoscale
    droplets with Drude optical response, nucleating in the bare insulating medium under the stimulating
    influence of the conditions of the specimen treatment. Simple effective medium theory is shown to
    provide a reasonable description of the experimental spectra in terms of the plasmon features due to
    the droplet phase.
    Golden, T.D., Shumsky, M.G., Zhou, Y., VanderWerf, R.A., Van Leeuwen, R.A., and Switzer, J.A.
    Electrochemical Deposition of Copper(I) Oxide Films 1996 Chemistry of Materials
    Vol. 8(10), pp. 2499-2504 
    article DOI  
    Abstract: Films of copper(I) oxide can be electrodeposited by reduction of copper(II) lactate in alkaline solution. Rietveld analysis of electrochemically grown films reveals pure copper(I) oxide with no copper(II) oxide or copper metal present in the films and a lattice parameter of a = 0.4266 nm. The cathodic deposition current is limited by a Schottky-like barrier that forms between the Cu2O and the deposition solution. A barrier height of 0.6 eV was determined from the exponential dependence of the deposition current on the solution temperature. At a solution pH of 9 the orientation of the film is [100], while at a solution pH of 12 the orientation changes to [111]. Atomic force images of the [100] oriented films have crystals shaped as four-sided pyramids, while the [111] films have triangular crystals. The grain size for films grown at 65 oC ranges from 2 to 5 mum. A refractive index of 2.6 was measured from the transmission spectrum for wavelengths between 1350 and 2800 nm. The p-type semiconductor has a direct bandgap of 2.1 eV.
    Goltzené, A., Schwab, C., and Wolf, H.C.
    Carrier Resonance in Cu2O 1976 Solid State Communications
    Vol. 18, pp. 1565-1567 
    article DOI  
    Goltzené, A. and Schwab, C.
    EPR Investigation of the Photomemory Effect of Cu2O 1978 Physica Status Solidi (a)
    Vol. 46, pp. K157-K161 
    article DOI  
    Goltzené, A. and Schwab, C.
    Impurity scattering effect on the cyclotron resonance of carriers in Cu2O 1979 Physica Status Solidi (b)
    Vol. 92, pp. 483-487 
    article DOI  
    Gonçalves, A.M.B., Campos, L.C., Ferlauto, A.S., and Lacerda, R.G.
    On the growth and electrical characterization of CuO nanowires by thermal oxidation 2009 Journal of Applied Physics
    Vol. 106(3), pp. 034303 
    article DOI  
    Abstract: We present a detailed study on the growth process of cupric oxide (CuO) nanowires by thermal oxidation. The morphology of nanowires, obtained at different oxidation temperatures and times, was determined. The diameter of nanowires was found to depend linear on temperature whereas the time dependence of their length is modeled by a parabolic law. The results suggest that CuO nanowires are formed as a result of the competition between grain boundary and lattice diffusion of Cu atoms across a Cu2O layer. Electrical characterization of the nanowires was also performed. A field effect transistor was produced with an isolated nanowire showing p-type characteristics. The resistivity, mobility, and density of carriers were calculated. Nanowire growth by thermal oxidation is very simple and has great potential to be used for large scale production; this opens possibilities for various kinds of application.
    Gorban, I.S., Gubanov, V.O., Dmitruk, I.M., and Kulakovskii, V.D.
    Luminescence of ultracold excitons in cuprous oxide crystal 2000 Journal of Luminescence
    Vol. 87-89, pp. 222-225 
    article DOI  
    Abstract: Two new bands were observed in luminescence spectrum of high-purity Cu2O crystal under resonant excitation. The detailed study of their shape and excitation spectra allowed us to interpret these bands as two-electron transitions in the non-equilibrium system of interacting ortho- and para-excitons. The schematics of energy spectrum and quantum transitions for this system are suggested. The influence of exciton-exciton scattering is under consideration.
    Goto, T., Shen, M.Y., Koyama, S., and Yokouchi, T.
    Bose-Einstein statistics of orthoexcitons generated by two-photon resonant absorption in cuprous oxide 1997 Physical Review B
    Vol. 55(12), pp. 7609-7614 
    article DOI  
    Greenwood, N.N. and Anderson, J.S.
    Conductivity and Thermo-Electric Effect in Cuprous Oxide 1949 Nature
    Vol. 164, pp. 346-347 
    article DOI  
    Abstract: Not Available
    Grondahl, L.O.
    Theories of a New Solid Junction Rectifier 1926 Science
    Vol. 64, pp. 306-308 
    article DOI  
    Grondahl, L.O. and Geiger, P.H.
    A new electronic rectifier 1927 Journal of the American Institute of Electrical Engineers
    Vol. 46, pp. 215 
    Grondahl, L.O.
    Unidirectional Current Carrying Device 1927 (1640335)  patent  
    Grondahl, L.O.
    Note on the Discovery of the Photoelectric Effect in a Copper-Oxide Rectifier 1932 Physical Review
    Vol. 40(4), pp. 635-636 
    article DOI  
    Grondahl, L.O.
    The Copper-Cuprous-Oxide Rectifier and Photoelectric Cell 1933 Reviews of Modern Physics
    Vol. 5, pp. 141 
    article DOI  
    Gross, E.F. and Karryev, N.A.
    1952 Doklady Akademii Nauk SSSR
    Vol. 84, pp. 261 
    Gross, E.F. and Karryev, N.A.
    1952 Doklady Akademii Nauk SSSR
    Vol. 84, pp. 471 
    Gross, E.
    Optical spectrum of excitons in the crystal lattice 1956 Il Nuovo Cimento (1955-1965)
    Vol. 3(0), pp. 672-701 
    article DOI  
    Gross, E.F.
    Optical spectrum and magneto-optical properties of excitons 1959 Journal of Physics and Chemistry of Solids
    Vol. 8, pp. 172-174 
    article DOI  
    Abstract: In a number of crystals at low temperatures a complex structure of distinct strong lines at the edge of fundamental absorption is observed. There is reason to believe that the structure is connected with the creation of excitons predicted by fSprenkel. In Cu2O one can observe a hydrogen-like series of narrow lines: showing the existence of Mott excitons in the crystal. The fact that their diameters are very large is confirmed by ionization (dissociation) of excitons observed even in weak electric fields (1 kV/cm). The quadratic diamagnetic Zeeman effect is detected in Cu2O and CdS which is a proof of the large dimensions of excitons and their enormous diamagnetism. The linear paramagnetic Zeeman effect of the members of the Cu2O series was not observed. That proves the existence of positronium-like excitons with equal effective masses of electron and hole. On the other hand some of the Cu2O and CdS absorption lines show the linear Zeeman splitting only. This can be explained by excitation of localized excitons whose radii do not exceed the size of the crystal cell. In such a case the spectra of ortho- and para-excitons may be different. Another phenomenon was observed in a magnetic field near the series limit of the Cu2O exciton spectrum. A group of almost equidistant absorption maxima beyond the exciton series limit with a fine structure has been detected. These maxima are due to the diamagnetic levels of LSpandau. The spacing between successive maxima is determined by the exciton cyclotron frequency which is equal to the halfsum of the cyclotron frequencies of the electron and hole. In luminescence in a number of crystals, narrow emission lines are observed at the very edge of the fundamental absorption nearly coinciding with the absorption lines. Some of these may have appeared as a result of annihilation of excitons with the emission of light. Some of the crystals show a fine structure of the spectral dependence of photoconductivity which is closely related to the line structure of the absorption edge. This reveals the role of excitons in photoconductivity.
    Gross, E.F. and Novikov, B.V.
    The fine structure of the spectral curves of photoconductivity and luminescence excitation and its correlation to the exciton absorption spectrum 1961 Journal of Physics and Chemistry of Solids
    Vol. 22, pp. 87-100 
    article DOI  
    Abstract: The exciton fine structure of the fundamental absorption edge in semiconductor crystals was examined. It was observed that substances having such a structure are fairly strong photo-conductors. This fact leads to the conclusion that there is a correlation between the exciton absorption lines and the shape of the photoconductivity curve. Crystals with well-known structures of the absorption edge (CdS, Cu2O, HgI2, PbI2 and GaSe) were chosen for investigation. A fine structure of the spectral curves of photoconductivity, corresponding to exciton absorption lines, was discovered in all the investigated crystals at low temperatures. Its properties in a CdS single crystal were studied in detail. It turned out that either the maxima (first type of crystals) or the minima (second type of crystals) on the photocurrent curves could correspond to the exciton absorption lines. By means of proper treatment crystals can be converted from one type into another and vice versa. The coincidence of photocurrent and absorption maxima is considered as a consequence of exciton participation in giving rise to photocurrent. Possible mechanisms of exciton participation in creating charge carriers are discussed. On the spectral curve of luminescence excitation of CdS crystals at low temperatures, a fine structure related to the exciton spectrum is also observed. Either maxima or minima on the excitation spectral curve coincide with the exciton absorption lines.
    Gross, E.F.
    Vol. 5(2), pp. 195-218 
    article DOI  
    Gross, E.F. and Kreihgol'd, F.I.
    Exciton Luminescence in Cu2O Crystals 1968 JETP Letters
    Vol. 7, pp. 218-220 
    article URL 
    Gross, E.F. and Agekyan, V.T.
    Polarizability of Exciton and Effect of the Reversal of the Magnetic Field in the Spectrum of the Yellow Exciton Series of a Crystal 1968 JETP Letters
    Vol. 8, pp. 373-376 
    article URL 
    Gross, E.F. and Kreingol'd, F.I.
    Lifetimes of Free and Bound Excitons in Cu2O Crystals 1969 JETP Letters
    Vol. 10, pp. 139-142 
    article URL 
    Gross, E.F. and Kreingol'd, F.I.
    Biexciton in Cu2O Crystal 1970 JETP Letters
    Vol. 12, pp. 68-70 
    article URL 
    Gross, E.F., Permogorov, S., Travnikov, V., and Selkin, A.
    Hot excitons and exciton excitation spectra 1970 Journal of Physics and Chemistry of Solids
    Vol. 31(12), pp. 2595-2606 
    article DOI  
    Abstract: Excitation Spectra (E.S.) of free exciton emission in CdS crystals are measured at 4.2 and 77�K both for zero-phonon emission lines (n = 1A,n = 1B and n = 2A) and for line of exciton annihilation with simultaneous creation of LO phonon (A1 - LO). Distinctly pronounced oscillating structure with energy period of LO phonon can be observed in the E.S. of all exciton emission lines. This structure arises due to kinetic energy relaxation processes in exciton bands, the appearance of oscilations is conditioned by incomplete thermalization of excitons during exciton life-time. Observation of discrete structure in the E.S. permits one to draw some conclusions concerning the mechanism of exciton formation under optical excitation. Creation of excitons with kinetic energies up to 0,2 eV, considerably exceeding the binding energy 0.03 eV, was observed. Non-equilibrium character of zerophonon free exciton emission is briefly discussed.
    Gross, E.F., Kreingol'd, F.I., and Makarov, V.L.
    Resonant Interaction Between Ortho- and Para-excitons with Participation of Phonons in a Cu2O Crystal 1972 JETP Letters
    Vol. 15, pp. 269-271 
    article URL 
    Grun, J.B., Sieskind, M., and Nikitine, S.
    Étude Spectrophotométrique des Spectres Continus de Cu2O a Diverses Temperatures 1961 Journal of Physics and Chemistry of Solids
    Vol. 19, pp. 189-197 
    article DOI  
    Grun, J.B., Sieskind, M., and Nikitine, S.
    Étude de l'absorption et de la réflexion de la cuprite aux très basses températures dans le visible de courtes longueurs d'onde 1961 Journal of Physics and Chemistry of Solids
    Vol. 21, pp. 119-122 
    article DOI  
    Grun, J.B., Sieskind, M., and Nikitine, S.
    Détermination de l'intensité d'oscillateur des raies de la série verte de Cu2O aux basses températures 1961 Journal de Physique et Le Radium
    Vol. 22(3), pp. 176-178 
    article DOI  
    Abstract: The green series of absorption lines in CU2O crystals has been studied by spectrophotometric methods at temperatures down to liquid helium. The oscillator strength, the maximum of the coefficient of absorption and the width of the first lines (n = 2) of the green series have been determinated and compared with the corresponding results for the yellow series.
    Grun, J.B. and Nikitine, S.
    Étude de la forme des raies des séries jaune et verte de la cuprite 1963 Journal de Physique
    Vol. 24(6), pp. 355-358 
    article DOI  
    Abstract: The experimental evidence in favour of the interpretation of the yellow and green series of Cu2O as a second class (weakly forbidden) exciton spectra is discussed. The shape of the absorption lines has been studied in detail and compared with Toyozawa's theory. Good agreement has been found with the Lorentzian unsymmétrical type of lines predicted by the theory.
    Grzesik, Z., Migdalska, M., and Mrowec, S.
    Chemical diffusion in non-stoichiometric cuprous oxide 2008 Journal of Physics and Chemistry of Solids
    Vol. 69, pp. 928-933 
    article DOI  
    Gu, Y.-e., Su, X., Du, Y., and Wang, C.
    Preparation of flower-like Cu2O nanoparticles by pulse electrodeposition and their electrocatalytic application 2010 Applied Surface Science
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: A pulsed electrodeposition technique based on a multipulse sequence of potentials of equal amplitude, duration and polarity was employed for preparation of highly dispersed flower-like cuprous oxide (Cu2O) nanoparticles. The morphology analysis of the particles using scanning electron microscope (SEM) reveals that the flower-like particles were from sequential growth of Cu2O along the (1�1�1) direction on the cubic Cu2O (1�0�0). The structure and the chemical composition of the deposits were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Optical property and band gap of the Cu2O was investigated using UV/vis diffuse reflection spectra (DRS), and the measured value of energy gap is 2.18�eV. The dark and light open circuit potential-time characterization study showed that the flower-like Cu2O nanoparticles exhibited good photoelectric response. Cyclic voltammetry carried out in the presence of p-nitrophenol (p-NP) shows that the electrocatalytic performance of the Cu2O particles for the reduction of p-NP, which was characterized by a cathodic peak at around -0.6�V. The influence of the incidence of light on the electrocatalysis is also discussed.
    Haimour, N., El-Bishtawi, R., and Ail-Wahbi, A.
    Equilibrium adsorption of hydrogen sulfide onto CuO and ZnO 2005 Desalination
    Vol. 181(1-3), pp. 145-152 
    article DOI  
    Abstract: Removal of hydrogen sulfide from aqueous solutions has been studied using cupric oxide (CuO) and zinc oxide (ZnO) as adsorbents. The adsorption capacity of both CuO and ZnO for H2S from aqueous solutions was determined under various conditions of temperature and solution pH. Equilibrium data were used to construct adsorption isotherms and to fit various adsorption models. Results show that increasing temperature leads to an increase in the adsorption capacity of both oxides. Studying the effect of pH at 4, 7 and 11 show that the maximum adsorption capacity of CuO is attained at pH 7. However, the Redlich-Peterson isotherm shows a better fit than both the Langmuir and Fruendlich isotherms.
    Hallstedt, B., Risold, D., and Gauckler, L.
    Thermodynamic assessment of the copper-oxygen system 1994 Journal of Phase Equilibria
    Vol. 15(5), pp. 483-499 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;The Cu-O system shows complete miscibility between the metallic liquid and the oxide liquid above ∼1623 K and a miscibility gap below that temperature. Because of the practical importance of the system, a wealth of experimental data exists, both on the phase diagram and on the thermodynamic properties. These data have been reviewed, and a consistent set of thermodynamic model parameters has been optimized. An ionic two-sublattice model was used to describe the liquid phase and was found to represent accurately the experimental data.
    Hammura, K., Sakai, K., Kobayashi, M., and Misu, A.
    Assignment of quasi-Landau levels in magneto-oscillatory spectra in cuprous oxide to classical unstable trajectories of hydrogen type atoms 1998 Physica B
    Vol. 246-247, pp. 416-420 
    article DOI  
    Abstract: It is found, for the first time in the field of solid state spectroscopy, that quasi-Landau levels in magneto-oscillatory spectra in cuprous oxide reflect "classical non-integrability." Cuprous oxide is well known to exhibit excitonic absorption spectra of typical wannier type near the absorption edge in yellow spectral region. Magneto-oscillatory spectra are observed in the region above the limiting energy of the exciton series in magnetic fields. The spectra are measured at liquid helium temperature with right and left circularly polarized light in magnetic fields up to 4.5 T generated by a superconducting magnet. The observed spectra look like "Landau levels" corresponding to the optical transitions between states of the hole in a valence band and those of the electron in a conduction band without Coulomb attraction between them qualitatively, but never coincide with the Landau levels quantitatively. By calculating inverse Fourier transform of the observed spectra (IFFT spectra), three peaks are found in the auto-correlation function of the excited excitonic state. These spectra are interpreted as those of a hydrogen type atom with the effective masses of the electron-hole pair in homogeneous magnetic field, which is known to be a typical non-integrable system in classical mechanics. Instead of obtaining the quantum mechanical motions of wave packet, the classical trajectories are numerically calculated. First peak of the IFFT spectra is assigned to the trajectories on which the wave packet circulates and returns to approximately to the starting point after the duration corresponding to the first peak. Immediately after that, the trajectories are rapidly apart from the starting point on account of their instability, which reflects the classical non-integrability of the system.
    Hammura, K. and Sakai, K.
    Manifestation of Classical Non-integrability in Magneto-oscillatory Spectra in Cuprous Oxide 2005 Journal of the Physical Society of Japan
    Vol. 74(3), pp. 1067-1070 
    article DOI  
    Abstract: The magneto-oscillatory spectra in cuprous oxide can be interpreted as reflecting classical non-integrability of the Hamiltonian of an electron–hole pair generated by the incident light in magnetic fields. The spectra have multi-oscillatory structure, and three periods are extracted from the spectra. It is found that the three periods coincide with three recurrence periods associated with corresponding three types of unstable classical trajectories. The instability is due to non-integrability of the system with spherical Coulomb and planar diamagneticpotential of magnetic fields. This type of analysis opens the way to get an evidence of “quantum chaos” in solid state.
    Han, S., Chen, H.-Y., Kuo, L.-T., and Tsai, C.-H.
    Characterization of cuprous oxide films prepared by post-annealing of cupric oxide using an atmospheric nitrogen pressure plasma torch 2008 Thin Solid Films
    Vol. 517(3), pp. 1195-1199 
    article DOI  
    Abstract: Cuprous oxide films were prepared by the post-annealing of cupric oxide using an atmospheric pressure microwave plasma torch. Metallic copper films were deposited on glass substrate by magnetron sputtering. Then the films were annealed in air at 500 °C for 12 h, and the formation of cupric oxide observed. The annealed films were further treated by nitrogen plasma at a power of 800 W for 10 and 20 min. The color of the film clearly changed from black to reddish brown over 10 min. X-ray diffraction patterns show that the annealed films were cupric oxide and included cuprous oxide diffraction peaks observed aftert 10 min in nitrogen plasma. The resistivity of annealed films was 16.7 [Omega] cm, and was reduced markedly to about one order of magnitude under nitrogen plasma. Annealing in air and nitrogen plasma treating shifted the optical band gap from 2.1 eV to 2.4 eV. The relationship between the microstructure and plasma content of the films and their properties is investigated.
    Han, K. and Tao, M.
    Electrochemically deposited p--n homojunction cuprous oxide solar cells 2009 Solar Energy Materials and Solar CellsSelected Papers from the Photovoltaics, Solar Energy Materials & Thin Films Symposium, Cancun, Mexico, 19 - 23 August 2007, XVI International Materials Research Congress
    Vol. 93(1), pp. 153-157 
    article DOI  
    Abstract: The electrical properties of both p- and n-type cuprous oxide (Cu2O) films electrochemically deposited from two electrolyte solutions were examined by current-voltage measurements. The resistivity of p-type Cu2O varied from 3.2�105 to 2.0�108�[Omega]�cm, while that of n-type Cu2O from 2.5�107 to 8.0�108�[Omega]�cm, depending on deposition conditions such as solution pH, deposition potential and temperature. With optimized deposition conditions for minimum resistivity, p-n homojunction Cu2O solar cells were fabricated by a two-step deposition process. The p-n homojunction Cu2O solar cells showed a conversion efficiency of 0.1% under AM1 illumination. The low efficiency is attributed to the high resistivity of p- and n-type Cu2O, which require doping to reduce.
    Han, X., Han, K., and Tao, M.
    Characterization of Cl-doped n-type Cu2O prepared by electrodeposition 2010 Thin Solid Films
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: N-type doping of cuprous oxide (Cu2O) films by chlorine (Cl) during electrodeposition was reported by the authors recently. A more detailed study on the effects of doping conditions on electrical properties of Cl-doped Cu2O is presented in this paper. The resistivity of Cl-doped Cu2O is affected by doping conditions, including Cu and Cl concentrations, different Cu and Cl precursors, complexing agent concentration, solution pH, and deposition temperature. It is believed that these conditions control the amount of Cl incorporated into the Cu2O films, thus the doping level. The lowest resistivity obtained so far is 7�[Omega]-cm, suitable for solar cell applications. Photocurrent-potential measurements verify the n-type conductivity of Cl-doped Cu2O. Scanning electron microscopy indicates a small grain size of around 100�nm in Cl-doped Cu2O. X-ray diffraction confirms Cu2O as the only detectable phase in the film.
    Hanke, L., Fröhlich, D., Ivanov, A.L., Littlewood, P.B., and Stolz, H.
    LA Phonoritons in Cu2O 1999 Physical Review Letters
    Vol. 83(21), pp. 4365-4368 
    article DOI  
    Hanke, L., Frölich, D., Ivanov, A.L., Littlewood, P.B., and Stolz, H.
    Spectroscopy of LA-Phonoritons in Cu2O 2000 Physica Status Solidi (b)
    Vol. 221, pp. 287-293 
    article DOI  
    Hao, Y. and Gong, H.
    The Influence of In/Cu Ratio on Electrical Properties of CuO:In Thin Films Prepared by Plasma-Enhanced CVD 2008 Chemical Vapor Deposition
    Vol. 14(1-2), pp. 9-13 
    article DOI  
    Abstract: CuO:In thin films were prepared by plasma-enhanced chemical vapor deposition (CVD) with Cu(acac)2 and In(acac)3 precursors. A unique method or facility in vaporizing solid-state precursors and the transportation to the CVD reactor was described. The structure of the films evolved from nano-crystalline characteristic to amorphous state as the In/Cu atomic ratio of the mixed precursors increased from 0 to 0.25. A dependence of the resistivity of the films on the indium concentration was found. A low room-temperature resistivity of 7.35 &OHgr;�cm was achieved for the sample of an In/Cu atomic ratio of 0.08, with an activation energy of 0.14�eV. X-ray photoelectron spectroscopy (XPS) study excluded the possibility that the increased conductivity of the samples came from a reduction of Cu2+ to Cu+. Positive holes (hbull) induced by negatively charged defect complex were assumed to contribute to the increase of conductivity.
    Hapase, M.G., Gharpurey, M.K., and Biswas, A.B.
    The oxidation of vacuum deposited films of copper 1968 Surface Science
    Vol. 9(1), pp. 87-99 
    article DOI  
    Abstract: A study of the oxygen uptake vs. temperature behaviour of vacuum deposited copper films in the range 50 to 400�C under 70 mm Hg oxygen pressure showed the existence of the phases CuO0.67 and CuO. Isothermal oxidation studies show the CuO0.67 phase to be stable at the lower temperatures (150-200�C) and the CuO at the higher temperatures (>300�C). In the intermediate range (~210-290�C) the product is also intermediate between the two. The low-temperature data show that a direct logarithmic rate law is obeyed and the activation energy is 5.58 kcal/mole. At 250�C, it is logarithmic as well as inverse logarithmic. At higher temperatures (>300�C) the behaviour is inverse logarithmic, the activation energy corresponding to 5.90 kcal/mole. The reason for the formation of CuO0.67 and CuO has been explained qualitatively.
    Hara, M., Kondo, T., Komoda, M., Ikeda, S., Kondo, J.N., Domen, K., Shinohara, K., and Tanaka, A.
    Cu2O as a photocatalyst for overall water splitting under visible light irradiation 1998 Chemical Communications, pp. 357-358  article DOI  
    Harris, W.W., Ball, F.L., and Gwathmey, A.T.
    The structure of oxide films formed on smooth faces of a single crystal of copper 1957 Acta Metallurgica
    Vol. 5(10), pp. 574-581 
    article DOI  
    Abstract: Oxide films, which were formed on the (311), (111), and (100) faces of a single crystal of copper heated at 150�C, were removed electrolytically from the copper and examined with an electron microscope. The structure of the oxide was found to be related to crystal face of the copper, and three types of structure were observed. On each face the film consisted of: 1. (1) small nuclei from less than 20 to 80 � in diameter, 2. (2) regularly shaped masses of oxide from 80 to 3000 � in diameter, and 3. (3) a crystalline base film initially unresolvable with the electron microscope.
    Harukawa, N., Murakami, S., Tamon, S., Ijuin, S., Ohmori, A., Abe, K., and Shigenari, T.
    Temperature dependence of luminescence lifetime in Cu2O 2000 Journal of Luminescence
    Vol. 87-89, pp. 1231-1233 
    article DOI  
    Haugsrud, R. and Kofstad, P.
    On the oxygen pressure dependence of High Temperature Oxidation of Copper 1997 Materials Science Forum
    Vol. 251-254, pp. 65-72 
    article DOI  
    Haugsrud, R. and Kofstad, P.
    On the High-Temperature Oxidation of Cu-Rich Cu-Ni Alloys 1998 Oxidation of Metals
    Vol. 50(3), pp. 189-213 
    article DOI  
    Abstract: Cu-2 wt.%Ni and Cu-5wt.%Ni were oxidized at 800to 1050°C and oxygen pressures from from 5 ×10-4 to 1 atm. The oxidation, as measured bythermogravimetry, was approximately parabolic. The oxidescales could be divided in two main regions: An outerregion consisting of copper oxides and an inner porousregion, which consists of Cu2O with dispersedNiO particles. NiO particles exists as internal-oxide particles. The interface between the two layersreflects the original surface, which shows that theouter part grows by outward Cu diffusion via vacancies.The inner part grows by outward diffusion of copper and inward transport of gaseous oxygen by thedissociative-transport mechanism. The amount ofporosity, the relative thickness of the inner layercompared to the total thickness of the scale, and theoxidation rate as a function of Ni content was dependenton the reaction conditions.
    Haugsrud, R. and Norby, T.
    Determination of Thermodynamics and Kinetics of Point Defects in Cu2O Using the Rosenburg Method 1999 Journal of Electrochemical Society
    Vol. 146, pp. 999-1004 
    article DOI  
    Haugsrud, R.
    The Influence of Water Vapor on the Oxidation of Copper at Intermediate Temperatures 2002 Journal of the Electrochemical Society
    Vol. 149(1), pp. B14-B21 
    article DOI  
    Hayashi, M. and Katsuki, K.
    Absorption Spectrum of Cuprous Oxide 1950 Journal of the Physical Society of Japan
    Vol. 5, pp. 380B-381 
    article DOI  
    Hayashi, M. and Katsuki, K.
    Hydrogen--Like Absorption Spectrum of Cuprous Oxide 1952 Journal of the Physical Society of Japan
    Vol. 7, pp. 599-603 
    article DOI  
    Hayashi, M.
    Absorption Spectrum of Copper-Coloured Cuprous Oxide 1959 Journal of the Physical Society of Japan
    Vol. 14(5), pp. 681 
    article DOI  
    Hayashi, M. and Ogawa, M.
    Absorption Spectra of Cuprous Oxide Quenched 1969 Journal of the Physical Society of Japan
    Vol. 26(1), pp. 121-136 
    article DOI  
    Haydar, A. and Coret, A.
    Excitonic photoconductivity and structural defects in Cu2O crystals 1980 Journal de Physique Colloques
    Vol. 41(C6), pp. C6-504-C6-507 
    article DOI  
    Haydar, A., Coret, A., and Oudjehane, N.
    Dark current-voltage characteristics of Cu2O crystals and their relation to structural defects 1982 Physica Status Solidi (a)
    Vol. 70(2), pp. 683-690 
    article DOI  
    Abstract: The dark current-voltage (J-U) characteristics of Cu2O crystals are measured for the first time in the temperature range between 4 and 300 K taking into account the direction of the applied electric field relative to the crystallographic directions. These J-U characteristics at low temperatures indicate the existence of potential barriers which are related to structural defects revealed by chemical etching. This view is supported by the observed anisotropy of the conductivity at low temperatures: at 4.2 K, the conductivity in the lang001rang direction is higher than in the lang110rang direction.
    He, J.-B., Lu, D.-Y., and Jin, G.-P.
    Potential dependence of cuprous/cupric duplex film growth on copper electrode in alkaline media 2006 Applied Surface Science
    Vol. 253, pp. 689-697 
    article DOI  
    Abstract: The duplex oxide film potentiostatically formed on copper in concentrated alkaline media has been investigated by XRD, XPS, negative-going voltammetry and cathodic chronopotentiometry. The interfacial capacity was also measured using fast triangular voltage method under quasi-stationary condition. The obvious differences in the thickness, composition, passivation degree and capacitance behavior were observed between the duplex film formed in lower potential region (‑0.13 to 0.18 V versus Hg|HgO electrode with the same solution as the electrolyte) and that formed in higher potential region (0.18 0.60 V). Cuprous oxides could be formed and exist stably in the inner layer in the both potential regions, and three cupric species, soluble ions and Cu(OH)2 and CuO, could be independently produced from the direct oxidation of metal copper, as indicated by three pairs of redox voltammetric peaks. One of the oxidation peaks appeared only after the scan was reversed from high potential and could be attributed to CuO formation upon the pre-accumulation of O2‑ ions within the film under high anodic potentials. A new mechanism for the film growth on the investigated time scale from 1 to 30 min is proposed, that is, the growth of the duplex film in the lower potential region takes place at the film|solution interface to form a thick Cu(OH)2 outer layer by field-assisted transfer of Cu2+ ions through the film to solution, whereas the film in the higher potential region grows depressingly and slowly at the metal|film interface to form Cu2O and less CuO by the transfer of O2‑ ions through the film to electrode.
    Heinemann, K., Rao, D.B., and Douglass, D.L.
    Oxide nucleation on thin films of copper duringin Situ oxidation in an electron microscope 1975 Oxidation of Metals
    Vol. 9(4), pp. 379-400 
    article DOI  
    Abstract: single-crystalline thin films of copper were oxidized at an isothermal temperature of 425°C and at an oxygen partial pressure of 5×10-3 Torr in situ in a high-resolution electron microscope. The specimens were prepared by epitaxial vapor deposition onto polished 100 and 110 faces of rocksalt and mounted in a hot stage inside an ultra-high-vacuum specimen chamber of the microscope. Large amounts of sulfur, carbon, and oxygen were detected by Auger electron spectroscopy on the surface of the as-received films and were removed in situ by ion-sputter etching immediately prior to the oxidation. The nucleation and growth characteristics of Cu2O on Cu were studied. The predominantly observed crystallographic orientations of Cu2O on 100 and 110 copper films were epitaxial, parallel 100 and 110 orientations, respectively. In addition, a Cu2O 111 orientation with Cu2O //Cu was found frequently on 100-oriented copper films. The distinct particle shapes observed most frequently were square and hexagonal, representing 100 and 111 orientations, respectively. An induction period of about 30 min was found, which did not depend on the film thickness but did depend strongly on the oxygen partial pressure and the oxygen exposure prior to the oxidation. Neither stacking faults nor dislocations were found to be associated with the Cu2O nucleation sites. The growth of Cu2O nuclei was found to be linear with time. The experimental findings, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving (a) the formation of a surface-charge layer, (b) oxygen saturation in the metal and formation of a supersaturated zone near the surface, and (c) nucleation, followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.
    Heltemes, E.C.
    Far-Infrared Properties of Cuprous Oxide 1966 Physical Review
    Vol. 141, pp. 803-805 
    article DOI  
    Herion, J.
    Chemical origin of the space-charge layer in cuprous oxide front-wall solar cells 1979 Applied Physics Letters
    Vol. 34(9), pp. 599-601 
    article DOI  
    Herion, J., Niekisch, E.A., and Scharl, G.
    Investigation of Metal Oxide/Cuprous Oxide Heterojunction Solar Cells 1980 Solar Energy Materials
    Vol. 4, pp. 101-112 
    article DOI  
    Herion, J., Niekisch, E.A., and Scharl, G.
    Metal oxide/cuprous oxide heterojunction solar cells 1980 Proceedings of the 14th IEEE Photovoltaic Specialists Conference, pp. 453-457  inproceedings  
    Herion, J., Scharl, G., and Tapiero, M.
    The effect of ion beams on the composition of Cu2O$(111)$ surfaces 1982--1983 Applications of Surface Science
    Vol. 14, pp. 233-248 
    article DOI  
    Hesse, J.F. and Compaan, A.
    Resonance Raman studies of annealing in He-, Na-, Cd-implanted cuprous oxide 1979 Journal of Applied Physics
    Vol. 50(1), pp. 206-213 
    article DOI  
    Hoa, N.D., An, S.Y., Dung, N.Q., Van Quy, N., and Kim, D.
    Synthesis of p-type semiconducting cupric oxide thin films and their application to hydrogen detection 2010 Sensors and Actuators B: Chemical
    Vol. 146(1), pp. 239-244 
    article DOI  
    Abstract: Nanostructured CuO thin films are synthesized by deposition and thermal oxidation of Cu on SiO2 substrates. The effects of oxidation temperatures on the morphologies and crystallinity of the CuO thin films are investigated by SEM, XRD, and XPS. The electrical and hydrogen sensing properties of CuO are studied by electrical resistance measurements. In addition, the effects of carrier gases on the gas response of CuO are investigated. The results showed that Cu was oxidized into monoclinic cupric oxide in the investigated temperature range from 300 to 800��C. The p-type semiconducting CuO thin film showed increases in electrical resistance upon exposure to hydrogen. The CuO thin film oxidized at 400��C showed the highest response as compared to others, and it was 3.72 for 6% H2 at an operating temperature of 250��C. The carrier gases played very important roles in the hydrogen sensing by CuO. That is, the sensor showed good response-and-recovery with a carrier gas of air but not with nitrogen.
    Hoa, N.D., Van Quy, N., Jung, H., Kim, D., Kim, H., and Hong, S.-K.
    Synthesis of porous CuO nanowires and its application to hydrogen detection 2010 Sensors and Actuators B: Chemical
    Vol. 146(1), pp. 266-272 
    article DOI  
    Abstract: Porous nanowire-structured cupric oxide (CuO) film is synthesized by deposition of Cu on porous single-walled carbon nanotube (SWNT) substrate followed by a thermal oxidation process. Oxidation is done in air at a temperature range of 300-800��C to oxidize the Cu while removing the SWNT template. The oxidation temperature determines the stoichiometry of the CuO formed, and thus the electrical property. The structures and electrical properties of the synthesized materials are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and current-voltage measurements. Sensing property is examined using hydrogen gas. Gas sensing mechanism and the advantages of nanowire structure as a sensor are also discussed. The best response and recovery results are observed with the CuO nanowires oxidized at 400��C at a working temperature of 250��C.
    Hodby, J.W., Jenkins, T.E., Schwab, C., Tamura, H., and Trivich, D.
    Cyclotron resonance of electrons and of holes in cuprous oxide, Cu2O 1976 Journal of Physics C: Solid State Physics
    Vol. 9, pp. 1429-1439 
    article DOI  
    Holmes, R.D., Kersting, A.B., and Arculus, R.J.
    Standard molar Gibbs free energy of formation for Cu2O: high-resolution electrochemical measurements from $900$ to $1300K$ 1989 The Journal of Chemical Thermodynamics
    Vol. 21(4), pp. 351-361 
    article DOI  
    Abstract: Oxygen-concentration cells with zirconia solid electrolytes have been used to make equilibrium measurements of the standard molar Gibbs free energy of formation for copper(I) oxide, [Delta]fGmo(Cu2O), over the temperature range from 900 to 1300 K. Compared with previous measurements, systematic errors due to thermal gradients across the zirconia solid electrolyte have been greatly reduced. Measurements with three different types of zirconia solid electrolytes have yielded results that differ by only �40 J�mol-1 (�0.2 mV). This is the best agreement yet achieved between solid electrolytes of different composition. Our recommended value for the standard molar enthalpy of formation, [Delta]fHmo(Cu2O, 298.15 K), is -(170.59�0.08) kJ�mol-1 (po = 1 � 105 Pa).
    Holzschuh, H. and Suhr, H.
    Deposition of copper oxide (Cu2O, CuO) thin films at high temperatures by plasma-enhanced CVD 1990 Applied Physics A
    Vol. 51(6), pp. 486-490 
    article DOI  
    Abstract: Copper-oxide films are deposited by plasma-enhanced CVD using copper acetylacetonate as a precursor. The influence of various experimental parameters on deposition rate, film composition and resistivity have been studied. The substrate temperature and the bias are the parameters which affect these properties the most. An increase of the substrate temperature changes the phases of the deposit from Cu2O-CuO over Cu2O to Cu. At temperatures ?500° C the deposition rates are high but the films consist mainly of metallic Cu. A negative bias enhances the deposition rate only slightly but has a strong effect on the film composition and can completely balance the oxygen deficiency. At a bias of -120 V the films consist of pure CuO even at temperatures ?500° C.
    Homma, T. and Yoneoka, T.
    Electron diffraction study of the epitaxy of Cu2O on the $(001)$ face of copper 1975 Journal of Applied Physics
    Vol. 46(4), pp. 1459-1464 
    article DOI  
    Hong, J., Li, J., and Ni, Y.
    Urchin-like CuO microspheres: Synthesis, characterization, and properties 2009 Journal of Alloys and Compounds
    Vol. 481(1-2), pp. 610-615 
    article DOI  
    Abstract: Urchin-like CuO microspheres have been successfully synthesized via a simple water-ethyleneglycol (water-EG) mixed-solvothermal route at 100��C for 12�h, employing cupric chloride (CuCl2) and potassium hydroxide (KOH) as starting reactants in the absence of any surfactant or template. The as-obtained product was characterized by means of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM). It was found that the volume ratio of water and EG played an important role in the formation of urchin-like CuO microspheres. The UV-vis absorption and the photocatalytic degradation for organic dyes of the final product were also studied.
    Hsieh, J.H., Kuo, P.W., Peng, K.C., Liu, S.J., Hsueh, J.D., and Chang, S.C.
    Opto-electronic properties of sputter-deposited Cu2O films treated with rapid thermal annealing 2008 Thin Solid Films
    Vol. 516, pp. 5449-5453 
    article DOI  
    Hsueh, T.-J., Hsu, C.-L., Chang, S.-J., Guo, P.-W., Hsieh, J.-H., and Chen, I.-C.
    Cu2O/n-ZnO nanowire solar cells on ZnO: Ga/glass templates 2007 Scripta Materialia
    Vol. 57, pp. 53-56 
    article DOI  
    Hu, Y.Z., Sharangpani, R., and Tay, S.-P.
    Kinetic investigation of copper film oxidation by spectroscopic ellipsometry and reflectometry 2000 Journal of Vacuum Science & Technology A
    Vol. 18(5), pp. 2527-2532 
    article DOI  
    Hu, J.P., Payne, D.J., Egdell, R.G., Glans, P.A., Learmonth, T., Smith, K.E., Guo, J., and Harrison, N.M.
    On-site interband excitations in resonant inelastic X--ray scattering from Cu2O 2008 Physical Review B
    Vol. 77, pp. 155115 
    article DOI  
    Hu, F., Chan, K.C., and Yue, T.M.
    Morphology and growth of electrodeposited cuprous oxide under different values of direct current density 2009 Thin Solid Films
    Vol. 518(1), pp. 120-125 
    article DOI  
    Abstract: The growth of Cu2O thin films electrodeposited by a two-electrode system with acid and alkaline electrolytes under different values of direct current (DC) densities was investigated. The microstructure of Cu2O thin films produced in the acid electrolyte changes from a ring shape to a cubic shape with increasing DC density, and the microstructure of Cu2O thin films produced in the alkaline electrolyte has a typical pyramid shape. The X-ray diffraction results show that Cu2O thin films can be electrodeposited over a larger current domain than those deposited by a three-electrode system. The growth of Cu2O thin films is examined under this domain, and the electrocrystallization process of such films is discussed taking into consideration the effect of current density on nucleation, cluster growth, and crystal growth.
    Huang, K.
    The long wave modes of the Cu2O lattice 1963 Zeitschrift für Physik A
    Vol. 171(1), pp. 213-225 
    article DOI  
    Abstract: The symmetry coordinates for the long wave modes of the Cu2O lattice are derived explicitly; the selection rules for the first order optical effects (absorption and combinatory scattering) are given. It is pointed out that owing to macroscopic field effects degeneracies cannot be ascertained on symmetry grounds alone, thus nine distinct frequencies are obtained instead of seven. A tentative estimate of the frequencies on a simple ionic model has been made, giving for one of the optically active modes ?=16.5 µ, in close agreement with the observed position of the strongest absorption peak. The tentative nature of such an estimate is stressed, and effects due to electrical polarisation of the ions and possible bond angle distortion forces are briefly discussed.
    Huang, L., Yanga, S.G., Li, T., Gua, B.X., Dua, Y.W., Lub, Y.N., and Shi, S.Z.
    Preparation of large-scale cupric oxide nanowires by thermal evaporation method 2004 Journal of Crystal Growth
    Vol. 260, pp. 130-135 
    article DOI  
    Abstract: Large-scale cupric oxide (CuO) nanowires have been synthesized by thermal evaporating copper foils in O2 ambient
    at the temperatures from 300C to 900C. Scanning electron microscopy (SEM), transmission electron microscopy
    (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) were performed on
    the study of the CuO nanowires. XRD studies reveal the possibility of two-steps of nanowire formation; HRTEM
    image shows the bicrystal structure of the nanowire; SEM studies indicate the relationship between the morphology of
    the prepared nanowires and the growth conditions. The growth of the nanowires seems to be vapor–solid (VS)
    Huang, Y.-L., Chou, M.H., Wu, S.Y., and Cheng, C.-L.
    Investigation of Quantum-Confinement Effect in a Single CuO Nanowire 2008 Japanese Journal of Applied Physics
    Vol. 47, pp. 703 
    article DOI  
    Abstract: Spatially well separated cupric oxide (CuO) nanowires grown using thermal oxidation method were examined to directly observe the scale structure evolution of lattice vibration modes. Scanning electron microscopy and high-resolution transmission electron microscopy studies revealed the single crystalline nature and microstructure of a single CuO nanowire. Phonon spectral evolution along the wire axis was investigated using confocal Raman spectroscopy by scanning a single nanowire. The Ag, Bg(1), and Bg(2) phonon modes of CuO that are quantum-confined in radial directions of the thin nanowire evidenced from the observed systematic red-shift, broadening of the peak profile. These results can be well explained based on the phonon confinement model.
    Huang, L., Peng, F., Yu, H., and Wang, H.
    Preparation of cuprous oxides with different sizes and their behaviors of adsorption, visible-light driven photocatalysis and photocorrosion 2009 Solid State Sciences
    Vol. 11(1), pp. 129-138 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu2O nanoparticles are substantially stable in ambient atmosphere and the Cu+ as main state exists on the surface of Cu2O nanoparticles. As-prepared Cu2O microparticles can exist stably as a Cu2O/CuO core/shell structure; and the Cu2+ as main state exists on the surface of Cu2O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu2O particles with different sizes were investigated in detail. The results show that Cu2O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu2O nanoparticles exhibit special property of adsorption. Cu2O microparticles have a higher photocatalytic activity than Cu2O nanoparticles because of its slower photocorrosion rate, although Cu2O microparticles have much lower adsorption capacity than Cu2O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu2O under visible light were also discussed.
    Huang, C.-Y., Chatterjee, A., Liu, S.B., Wu, S.Y., and Cheng, C.-L.
    Photoluminescence properties of a single tapered CuO nanowire 2010 Applied Surface Science
    Vol. 256(11), pp. 3688-3692 
    article DOI  
    Abstract: Photoluminescence spectroscopy has been employed in order to explore the optical emission properties of a single CuO nanowire, grown on a copper grid in static air by simple thermal oxidation method. As the diameter of the single tapered CuO nanowire decreases, the green emission of the nanowire gradually shifts towards the higher energy side. A steady blue shift of 20 nm of the photoluminescence (PL) peak has been attributed to nanosize effect. Higher surface to volume ratio and enhanced surface defects along the growth direction of the nanowire might be responsible for the observed PL behavior. In addition, crystallization process along the length of the nanowire during growth to form pure CuO structure from the precursor state may also have some role in observed shift in the PL peak.
    Huang, L., Zhang, S., Peng, F., Wang, H., Yu, H., Yang, J., Zhang, S., and Zhao, H.
    Electrodeposition preparation of octahedral-Cu2O-loaded TiO2 nanotube arrays for visible light-driven photocatalysis 2010 Scripta Materialia
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: Octahedral-Cu2O-particle-loaded TiO2 nanotube (TNT) arrays were prepared by anode oxidation and subsequent cathodic deposition, and used as photocatalyst to degrade Acid Orange II under the irradiation of visible light. The results demonstrate that the photocatalytic activity of the TNT was significantly enhanced by the incorporation of octahedral Cu2O. Furthermore, exposure of a large area of 1�1�1 facets of octahedral Cu2O into TNT arrays augments the adsorption property and photocatalytic activity of TNT.
    Hulin, D., Mysyrowicz, A., and Benoît à la Guillame, C.
    Evidence for Bose-Einstein Statistics in an Exciton Gas 1980 Physical Review Letters
    Vol. 45, pp. 1970-1973 
    article DOI  
    Hung, L.-I., Tsung, C.-K., Huang, W., and Yang, P.
    Room-Temperature Formation of Hollow Cu2O Nanoparticles 2010 Advanced Materials
    Vol. 22, pp. 1910-1914 
    article DOI  
    Abstract: Monodisperse Cu and Cu2O nanoparticles (NPs) are synthesized using tetradecylphosphonic acid as a capping agent. Dispersing the NPs in chloroform and hexane at room temperature results in the formation of hollow Cu2O NPs and Cu@Cu2O core/shell NPs, respectively. The monodisperse Cu2O NPs are used to fabricate hybrid solar cells with efficiency of 0.14% under AM 1.5 and 1 Sun illumination.
    Iguchi, E., Yajima, K., and Saito, Y.
    Oxidation Kinetics of Cu to Cu2O 1973 Transactions of the Japan Institute of Metals
    Vol. 14, pp. 423-430 
    article URL 
    Iijima, J., Lim, J.-W., Hong, S.-H., Suzuki, S., Mimura, K., and Isshiki, M.
    Native oxidation of ultra high purity Cu bulk and thin films 2006 Applied Surface Science
    Vol. 253, pp. 2825-2829 
    article DOI  
    Abstract: The effect of microstructure and purity on the native oxidation of Cu was studied by using angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and spectroscopic ellipsometry (SE). A high quality copper film prepared by ion beam deposition under a substrate bias voltage of ‑50 V (IBD Cu film at Vs = ‑50 V) showed an oxidation resistance as high as an ultra high purity copper (UHP Cu) bulk, whereas a Cu film deposited without substrate bias voltage (IBD Cu film at Vs = 0 V) showed lower oxidation resistance. The growth of Cu2O layer on the UHP Cu bulk and both types of the films obeyed in principle a logarithmic rate law. However, the growth of oxide layer on the IBD Cu films at Vs = 0 and ‑50 V deviated upward from the logarithmic rate law after the exposure time of 320 and 800 h, respectively. The deviation from the logarithmic law is due to the formation of CuO on the Cu2O layer after a critical time.
    Ikeda, S., Takata, T., Kondo, T., Hitoki, G., Hara, M., Kondo, J.N., Domen, K., Hosono, H., Kawazoe, H., and Tanaka, A.
    Mechano-catalytic overall water splitting 1998 Chemical Communications, pp. 2185-2186  article DOI  
    Inaba, H.
    Reaction and diffusion path of an interface reaction between Cu2O and nickel 1997 Journal of Materials Science
    Vol. 32(1), pp. 91-97 
    article DOI  
    Abstract: The interface reaction between Cu2O and nickel has been investigated and the reaction path has been analysed on the chemical potential diagram for undoped and doped samples. The layer sequence of products Cu2O/Cu/NiO/Ni for the undoped sample and that of Cu2O/Cu/NiO/Cu–Ni alloy/Ni for the doped sample was obtained. The reaction and diffusion path was explained on the chemical potential diagram of the Cu–Ni–O system, based on the assumption that a local equilibrium is attained at the interfaces. The doping effect of NiO in Cu2O was ascribed to a higher mobility of copper in NiO phase due to the higher chemical potential of oxygen at the Cu/NiO interface resulting from the higher chemical potential of nickel in Cu2O. When the reaction time becomes longer, it is expected that the reaction and diffusion path will become similar to that of the doped sample. Because the reaction and diffusion path is a function of time and has a non-equilibrium character, it can be represented and reasonably explained on the chemical potential diagram obtained from a thermodynamic treatment.
    Inguanta, R., Sunseri, C., and Piazza, S.
    Photoelectrochemical Characterization of Cu2O-Nanowire Arrays Electrodeposited into Anodic Alumina Membranes 2007 Electrochemical and Solid-State Letters
    Vol. 10(12), pp. K63-K66 
    article DOI  
    Ishihara, T., Higuchi, M., Takagi, T., Ito, M., Nishiguchi, H., and Takita, Y.
    Preparation of CuO thin films on porous BaTiO$_3$ by self-assembled multibilayer film formation and application as a CO2 sensor 1998 Journal of Materials Chemistry
    Vol. 8(9), pp. 2037-2042 
    article DOI  
    Abstract: Preparation of CuO thin films by decomposition of self-assembled multibilayer films as a molecular template was investigated. Furthermore, the CO2 sensing property of the resultant CuO thin films on a porous BaTiO3 was investigated as a capacitive type sensor. Self-assembled bilayer films of a few 1000 layers thickness can be readily obtained by casting an aqueous suspension composed of dimethyldihexadecylammoniun bromide (DC1–16), Cu(CH3CO2)2 , hexadecylethylenediamine and poly(vinyl alcohol). Divalent copper ions (Cu2+) which are associated with two hexadecylethylenediamine molecules were arranged in the hydrophobic layer of the multibilayer film. Rapid heating to the combustion temperature of DC1–16 was desirable for removing organic molecules in the multibilayer template. Thin films of CuO can be obtained by calcination at temperatures higher than 573 K. The resultant CuO thin films were porous and consisted of fine particles. The capacitance of CuO thin films prepared from self-assembled multibilayer films as a molecular template on the BaTiO3 porous substrate exhibited a high sensitivity to CO2 , which is twice that of a conventional mixed oxide capacitor of CuO–BaTiO3 . The capacitance of CuO thin films on BaTiO3 increases with increasing CO2 concentration in the range from 100 ppm to 50% at 873 K. Consequently, it is concluded that CuO thin films on BaTiO3 were appropriate capacitive type CO2 sensors.
    Ishizuka, S., Maruyama, T., and Akimoto, K.
    Thin-Film Deposition of Cu2O by Reactive Radio-Frequency Magnetron Sputtering 2000 Japanese Journal of Applied Physics
    Vol. 39, pp. L786-L788 
    article DOI  
    Ishizuka, S., Kato, S., Maruyama, T., and Akimoto, K.
    Nitrogen Doping into Cu2O Thin Films Deposited by Reactive Radio--Frequency Magnetron Sputtering 2001 Japanese Journal of Applied Physics
    Vol. 40, pp. 2765-2768 
    article DOI  
    Ishizuka, S., Kato, S., Okamoto, Y., and Akimoto, K.
    Control of hole carrier density of polycrystalline Cu2O thin films by Si doping 2002 Applied Physics Letters
    Vol. 80, pp. 950-952 
    article DOI  
    Ishizuka, S., Kato, S., Okamoto, Y., and Akimoto, K.
    Hydrogen treatment for polycrystalline nitrogen-doped Cu2O thin film 2002 Journal of Crystal Growth
    Vol. 237-239, pp. 616-620 
    article DOI  
    Ishizuka, S., Kato, S., Okamoto, Y., Sakurai, T., Akimoto, K., Fujiwara, N., and Kobayashi, H.
    Passivation of defects in polycrystalline Cu2O thin films by hydrogen or cyanide treatment 2003 Applied Surface Science
    Vol. 216, pp. 94-97 
    article DOI  
    Ishizuka, S. and Akimoto, K.
    Control of the growth orientation and electrical properties of polycrystalline Cu2O thin films by group-IV elements doping 2004 Applied Physics Letters
    Vol. 85, pp. 4920-4922 
    article DOI  
    Ishizuka, S., Suzuki, K., Okamoto, Y., Yanagita, M., Sakurai, T., Akimoto, K., Fujiwara, N., Kobayashi, H., Matsubara, K., and Niki, S.
    Polycrystalline $n$-ZnO/$p$-Cu2O heterojunctions grown by RF-magnetron sputtering 2004 Physica Status Solidi (c)
    Vol. 1, pp. 1067-1070 
    article DOI  
    Isobe, M. and Masumi, T.
    Default of the Resonant Conjugation of Photoconductivity of Cu2O in Low-$T_c$ Superconductor Based Optoelectronic Devices 1996 Journal of the Physical Society of Japan
    Vol. 65(12), pp. 4088-4089 
    article DOI  
    Ito, T. and Masumi, T.
    Detailed Examination of Relaxation Processes of Excitons in Photoluminescence Spectra of Cu2O 1997 Journal of the Physical Society of Japan
    Vol. 66, pp. 2185-2193 
    article DOI  
    Ito, T., Yamaguchi, H., Okabe, K., and Masumi, T.
    Single-crystal growth and characterization of Cu2O and CuO 1998 Journal of Materials Science
    Vol. 33(14), pp. 3555-3566 
    article DOI  
    Abstract: We have prepared a large number of crystals of cuprous oxide (Cu2O) by various procedures. Photoluminescence spectra of these crystals were studied to examine the concentration of defects, especially copper vacancy VCu to seek favourable conditions for growing Cu2O crystal. High-quality single crystals of Cu2O were prepared by the floating-zone melting method in air. Several synthetic crystals (specimens FA, FZ and GZ) and also a natural crystal were studied by X-ray analysis, inductively coupled plasma spectroscopy analysis, optical absorption, photoluminescence, photoconductivity and cyclotron resonance absorption, photoluminescence, photoconductivity and cyclotron resonance absorption to characterize their optical and electrical qualities. The best values of mobility and scattering time of photocarriers at T = 4.2 K are estimated to be µh˜1.8 × 105 cm2 V-1 s-1 and th˜60 ps for positive holes, and µ•˜1.3 × 105 cm2 V-1 s-1 and t•˜70 ps for electrons in Cu2O. Further, we report preliminary experimental results on transport property of crystals also of cupric oxide (CuO) purified by the floating-zone melting method.
    Ito, T., Kawashima, T., Yamaguchi, H., Masumi, T., and Adachi, S.
    Optical Properties of Cu2O Studied by Spectroscopic Ellipsometry 1998 Journal of the Physical Society of Japan
    Vol. 67, pp. 2125-2131 
    article DOI  
    Ito, T., Yamaguchi, H., Masumi, T., and Adachi, S.
    Optical Properties of CuO Studied by Spectroscopic Ellipsometry 1998 Journal of the Physical Society of Japan
    Vol. 67(9), pp. 3304-3309 
    article DOI  
    Abstract: The real (ε1) and imaginary (ε2) parts of the dielectric function of polycrystalline samples of monoclinic CuO have been measured by spectroscopic ellipsometry in the 1.2–5.0-eV photon-energy range at room temperature. The CuO crystals having a grain size of the order of 1×1 mm2 were successfully grown by a floating-zone melting technique. Dielectric-function spectra of polycrystalline CuO reveal distinct structures at energies of E1∼1.6 eV, E2∼2.0 eV, E3∼2.6 eV and E4∼3.4 eV. These spectra are analyzed on the basis of a harmonic oscillator approximation. Dielectric-related optical constants, such as the complex refractive index (n*=n+ ik), absorption coefficient (α) and normal-incidence reflectivity (R), of CuO are also presented.
    Itoh, T. and Narita, S.-I.
    Study of Absorption Spectra of Excitons in Cu2O by Wavelength Modulation Technique 1975 Journal of the Physical Society of Japan
    Vol. 39, pp. 132-139 
    article DOI  
    Itoh, T. and Narita, S.-I.
    Analysis of Wavelength Derivative Spectra of Exciton in Cu2O 1975 Journal of the Physical Society of Japan
    Vol. 39, pp. 140-147 
    article DOI  
    Itoh, T. and Maki, K.
    Preferentially oriented thin-film growth of CuO$(111)$ and Cu2O$(001)$ on MgO$(001)$ substrate by reactive dc-magnetron sputtering 2007 Vacuum
    Vol. 81, pp. 904-910 
    article DOI  
    Itoh, T. and Maki, K.
    Growth process of CuO$(111)$ and Cu2O$(001)$ thin films on MgO$(001)$ substrate under metal-mode condition by reactive dc-magnetron sputtering 2007 Vacuum
    Vol. 81, pp. 1068-1076 
    article DOI  
    Ivanda, M., Waasmaier, D., Endriss, A., Ihringer, J., Kirfel, A., and Kiefer, W.
    Low-Temperature Anomalies of Cuprite Observed by Raman Spectroscopy and X-Ray Powder Diffraction 1997 Journal of Raman Spectroscopy
    Vol. 28, pp. 487-493 
    article DOI  
    Ivill, M., Overberg, M.E., Abernathy, C.R., Norton, D.P., Hebard, A.F., Theodoropoulou, N., and Budai, J.D.
    Properties of Mn-doped Cu2O semiconducting thin films grown by pulsed-laser deposition 2003 Solid State Electronics
    Vol. 47, pp. 2215-2220 
    article DOI  
    Iwanowski, R.J. and Trivich, D.
    The influence of hydrogen ion bombardment on the photovoltaic properties of Cu/Cu2O Schottky barrier solar cells 1983 Radiation Effects and Defects in Solids
    Vol. 76(3), pp. 87-92 
    article DOI  
    Abstract: The influence of hydrogen ion bombardment on the photovoltaic properties of Cu/Cu2O Schottky barrier solar cells was investigated. Two main cases of junction formation process were considered depending on the sequence of applied procedures: thermal evaporation of thin Cu layer and irradiation of the substrate by H+ ion beam.
    Iwanowski, R.J. and Trivich, D.
    Cu/Cu2O Schottky barrier solar cells prepared by multistep irradiation of a Cu2O substrate by H$^+$ ions 1984--1985 Solar Cells
    Vol. 13(3), pp. 253-264 
    article DOI  
    Abstract: The method of multistep irradiation of a Cu2O substrate by an H+ ion beam has been introduced for the preparation of Cu/Cu2O Schottky barrier solar cells. Cu2O samples were exposed first to an H+ beam with the beam voltage Vb fixed between 150 and 950 V (step I) and subsequently to a radiation dose of low energy H+ ions (Vb = 150 V) (step II). Both dark and illuminated (air mass 1) current-voltage characteristics of the cells were examined at 300 K after each step of the junction formation process. A detailed analysis of the influence of step II of the process on the main solar cell parameters (Voc, Jsc, fill factor and [eta]) and the diode parameters (n and J0) has been performed. The quality of the thin film copper electrode layer obtained by H+-ion-induced surface reduction of Cu2O was found to be better than that obtained by the single-step process. This resulted in an improvement in the conversion efficiency of Cu/Cu2O Schottky barrier solar cells up to [eta] [approximate] 1.5%.
    Iwanowski, R.J. and Trivich, D.
    Enhancement of the photovoltaic conversion efficiency in Cu/Cu2O Schottky barrier solar cells by H$^+$ ion irradiation 1986 Physica Status Solidi (a)
    Vol. 95(2), pp. 735-741 
    article DOI  
    Abstract: A new preparation method of Cu/Cu2O Schottky barrier solarcells is proposed and worked out. It combines resistive evaporation of a thin semitransparent copper electrode on a Cu2O substrate (step I) and exposition of the obtained junction to the H+ ion irradiation (step II). Both, dark and illuminated (AMI) current-voltage characteristics of the cells are recorded at room temperature after each step of the junction formation process. Especially, the influence of H+ ion beam voltage, Ub, on the main solar cell parameters is analysed here. It is proved that low energy H+ ion irradiation (0 &lt; Ub &lap; 250 V) provides significant enhancement of the photovoltaic conversion efficiency of the Cu/Cu2O solar cells.
    Izaki, M., Kobayashi, Y., Katayama, J.-i., and Ohtomo, S.
    Chemical Formation of Ohmic Cu Layer on Highly Resistive Cu2O 2006 Journal of the Electrochemical Society
    Vol. 153(9), pp. C612-C615 
    article DOI  
    Izaki, M., Mizuno, K.-t., Shinagawa, T., Inaba, M., and Tasaka, A.
    Photochemical Construction of Photovoltaic Device Composed of p-Copper(I) Oxide and n-Zinc Oxide 2006 Journal of the Electrochemical Society
    Vol. 153(9), pp. C668-C672 
    article DOI  
    Izaki, M., Shinagawa, T., Mizuno, K.-T., Ida, Y., Inaba, M., and Tasaka, A.
    Electrochemically constructed p-Cu2O/n-ZnO heterojunction diode for photovoltaic device 2007 Journal of Physics D
    Vol. 40(11), pp. 3326-3329 
    article DOI  
    Abstract: Polycrystalline n-ZnO/p-Cu2O heterojunctions have been fabricated by low-temperature eletrodepositions of ZnO and Cu2O layers in aqueous solutions. The condition for forming the Cu2O layer significantly reflected the electrical rectification characteristic and the photovoltaic performance, and the heterojunction fabricated under optimized conditions showed an excellent electrical rectification characteristic and a photovoltaic performance of 1.28% in conversion efficiency under an AM 1.5 illumination.
    Jackson, A.D. and Kavoulakis, G.M.
    Propagation of exciton pulses in semiconductors 2002 Europhysics Letters
    Vol. 59(6), pp. 807-813 
    article DOI  
    Abstract: Using a toy model, we examine the propagation of excitons in Cu 2 O, which form localized pulses under certain experimental conditions. The formation of these waves is attributed to the effect of dispersion, non-linearity and the coupling of the excitons to phonons, which acts as a dissipative mechanism.
    Jana, S. and Biswas, P.K.
    Optical characterization of in-situ generated Cu2O excitons in solution derived nano-zirconia film matrix 1997 Materials Letters
    Vol. 32(4), pp. 263-270 
    article DOI  
    Abstract: Cu2O excitons were generated in-situ in a nano-zirconia film matrix on silica glass substrate from the precursor solution containing Cu(II) nitrate trihydrate and zirconium oxychloride octahydrate. The films were annealed in the temperature range 200-1200 �C and characterized by transmission electron microscopy (TEM), UV-VIS-NIR and fluorescence spectroscopy. In the UV-VIS spectra of the films most of the UV and visible bands shifted towards longer wavelengths with increasing annealing temperature and the corresponding Cu2O microcrystallite size was evaluated from the shifting of the UV bands (271-371 nm). Wannier hydrogen-like excitonic transitions, e.g., blue, green, yellow series of Cu2O excitons were observed in the visible region. Excitation dependent fluorescence bands were observed in the visible region and the 400 nm excitation depicted two distinct fluorescence bands in the green ([small tilde] 525 nm) and red ([small tilde] 630 nm) regions. The intensity ratios of green and red fluorescences and vice versa were found to be dependent on the microcrystallite size. Tentative band assignments have been proposed from the excitonic absorption and fluorescence bands.
    Jang, J.I., O'Hara, K.E., and Wolfe, J.P.
    Spin-exchange kinetics of excitons in Cu2O: Transverse acoustic phonon mechanism 2004 Physical Review B
    Vol. 70(19), pp. 195205 
    article DOI  
    Jang, J.I.
    Lifetimes of Excitons in Cuprous Oxide 2005 School: University of Illinois at Urbana-Champaign  phdthesis URL 
    Jang, J.I. and Wolfe, J.P.
    Relaxation of stress-split orthoexcitons in Cu2O 2006 Physical Review B
    Vol. 73(7), pp. 075207 
    article DOI  
    Jang, J.I. and Wolfe, J.P.
    Exciton decay in Cu2O at high density and low temperature: Auger recombination, spin-flip scattering, and molecule formation 2006 Solid State Communications
    Vol. 137(1-2), pp. 91-96 
    article DOI  
    Abstract: In this paper, we examine the relative importance of three density-dependent decay mechanisms for excitons in cuprous oxide (Cu2O). Rate-equation models including Auger recombination (A), spin-flip scattering (B) and capture into short-lived biexcitons (C) are compared to photoluminescence data for a crystal temperature of 2�K. Process B--converting two orthoexcitons into two paraexcitons by exchanging electrons and holes--leaves the total exciton number unchanged and is inconsistent with the late-time data. In processes A and C, paraexcitons re-generate high energy excitons in agreement with the late-time data; however, the existing theory of Auger recombination seems to eliminate process A, leaving molecule formation as the dominant process.
    Jang, J.I. and Wolfe, J.P.
    Auger recombination and biexcitons in Cu2O: A case for dark excitonic matter 2006 Physical Review B
    Vol. 74(4), pp. 045211 
    article DOI  
    Jang, J.I., Sun, Y., Watkins, B., and Ketterson, J.B.
    Bound excitons in Cu2O: Efficient internal free exciton detector 2006 Physical Review B
    Vol. 74(23), pp. 235204 
    article DOI  
    Jang, J.I. and Ketterson, J.B.
    Impact of impurities on orthoexciton-polariton propagation in Cu2O 2007 Physical Review B
    Vol. 76(15), pp. 155210 
    article DOI  
    Jang, J.I., Sun, Y., and Ketterson, J.B.
    Indirect generation of quadrupole polaritons from dark excitons in Cu2O 2008 Physical Review B
    Vol. 77, pp. 075201 
    article DOI  
    Jang, J.I. and Ketterson, J.B.
    Suppression of molecule formation for orthoexciton-polaritons in Cu2O 2008 Solid State Communications
    Vol. 146(3-4), pp. 128-132 
    article DOI  
    Abstract: The lifetime of dense orthoexcitons in Cu2O is severely limited by dark molecule formation. In order to investigate this two-body process for orthoexciton-polaritons, we employ two-photon excitation and resonantly create orthoexciton-polaritons at 2�K, which are the coherent quantum superposition of orthoexcitons and the light field. Based on the steady-state analysis, we find that this density-dependent process is an order of magnitude reduced for resonantly created orthoexciton-polaritons compared with thermalized orthoexcitons at 2�K. This most likely arises from the photonic character of an orthoexciton-polariton. Considering the greatly reduced effective mass of the orthoexciton-polariton, this implies that the experimentally achievable orthoexciton-polariton densities can be above the critical density for Bose-Einstein condensation. However, insufficient elastic scattering seems to keep this propagating quantum ensemble from internal equilibrium.
    Jayathileke, K.M.D.C., Siripala, W., and Jayanetti, J.K.D.S.
    Donor and Acceptor Density Variations in Electrodeposited Cuprous Oxide Thin Films 2007 Proceedings of the Technical Sessions of the Institute of Physics - Sri Lanka
    Vol. 23, pp. 55-59 
    inproceedings URL 
    Jayatissa, A.H., Guo, K., and Jayasuriya, A.C.
    Fabrication of cuprous and cupric oxide thin films by heat treatment 2009 Applied Surface Science
    Vol. 255(23), pp. 9474-9479 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) and cupric oxide (CuO) thin films were prepared by thermal oxidation of copper films coated on indium tin oxide (ITO) glass and non-alkaline glass substrates. The formation of Cu2O and CuO was controlled by varying oxidation conditions such as, oxygen partial pressure, heat treatment temperature, and oxidation time. The microstructure, crystal direction, and optical properties of copper oxide films were measured with X-ray diffraction, atomic force microscopy, and optical spectroscopy. The results indicated that the phase-pure Cu2O and CuO films were produced in the oxidation process. Optical transmittance and reflectance spectra of Cu2O and CuO clearly exhibited distinct characteristics related to their phases. The electrical properties indicated that these films formed ohmic contacts with Cu and ITO electrode materials. Multilayers of Cu2O/CuO were fabricated by choosing the oxidation sequence. The experimental results in this paper suggest that the thermal oxidation method can be employed to fabricate device quality Cu2O and CuO films that are up to 200-300�nm thick.
    Jayewardena, C., Hewaparakrama, K.P., Wijewardena, D.L.A., and Guruge, H.
    Fabrication of n-Cu2O electrodes with higher energy conversion efficiency in a photoelectrochemical cell 1998 Solar Energy Materials and Solar Cells
    Vol. 56(1), pp. 29-33 
    article DOI  
    Abstract: We observed an n-type photoresponse in cuprous oxide films, which were prepared by a simple method of immersing copper plates in a HCl solution of 3�pH at 40�C temperature, when they were used in a PEC cell. This photoresponse was much higher than the previously published values for n-Cu2O electrodes which were prepared by other methods. The photocurrent obtained was in the order of 0.3�mA/cm2 when the cell was illuminated with light intensity of 50�mW/cm2. (The semiconductor electrode was biased to get a zero dark current.) The power conversion efficiency of the cell was 0.01%. The maximum quantum efficiency obtained was 15%. It is hoped that these values could be improved with a better understanding of the photoelectrochemical properties of the cell.
    Jeong, S.S., Mittiga, A., Salza, E., Masci, A., and Passerini, S.
    ZnO/Cu2O Solar Cells Made by Electrodeposition 2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy, pp. 528  inproceedings  
    Jeong, S.S., Mittiga, A., Salza, E., Masci, A., and Passerini, S.
    Electrodeposited ZnO/Cu2O heterojunction solar cells 2008 Electrochimica Acta
    Vol. 53(5), pp. 2226-2231 
    article DOI  
    Abstract: In this paper the fabrication and the characterization of heterojunction solar cells based on electrodeposited ZnO and Cu2O is described. The effect of the electrodeposition conditions (pH and temperature) on the cell performance has been investigated. The cells made with a Cu2O layer deposited at high pH (12) and moderate temperature (50��C) have shown conversion efficiency as high as 0.41%.
    Ji, J.-Y., Shih, P.-H., Yang, C.C., Chan, T.S., Ma, Y.-R., and Wu, S.Y.
    Spontaneous self-organization of Cu2O/CuO core--shell nanowires from copper nanoparticles 2010 Nanotechnology
    Vol. 21(4), pp. 045603 
    article DOI  
    Abstract: We report on the formation and spontaneous self-organization of Cu 2 O/CuO core–shell nanowires from individual copper nanoparticles. The growth process is interpreted using the results of time-dependent in situ x-ray diffraction. High-resolution transmission electron microscopy is used to observe the intermediate state of pearl-necklace-like aggregates that form a chain-like configuration of Cu 2 O nanoparticles intertwined into nanowires. The existence of an amorphous CuO shell is confirmed by the XANES technique and explained through an intensity simulation using a proposed core–shell nanowire model.
    Jimenez-Cadena, G., Comini, E., Ferroni, M., and Sberveglieri, G.
    Synthesis of Cu2O bi-pyramids by reduction of Cu(OH)2 in solution 2010 Materials Letters
    Vol. 64(3), pp. 469-471 
    article DOI  
    Abstract: In this paper we describe the synthesis of Cu2O bi-pyramids by reduction of Cu(OH)2 using hydrazine as reducing agent. Copper chloride is used as a precursor to produce copper hydroxide in aqueous solution and the precipitation of the product is controlled by a slow addition of the reducing agent. All the reactions have been carried out at room temperature and atmospheric pressure with high repeatability. The purification process does not require expensive methods since a solid product is obtained from a reaction in liquid phase. Scanning and Transmission electron microscopy characterization showed interesting bi-pyramidal structures of several microns of edge and different sizes.
    Jiménez-Melendo, M., Domínguez-Rodríguez, A., and Castaing, J.
    Point defect concentration relaxation and creep transients in binary oxides 1995 Acta Metallurgica et Materialia
    Vol. 43(10), pp. 3589-3604 
    article DOI  
    Abstract: In non-stoichiometric oxides (NiO, CoO, Cu2O...) two thermodynamic parameters (temperature T and partial pression of oxygen Po2) are necessary in order to fix the population of point defects. When one of these two parameters (T or Po2) is suddenly changed and a physical property is continuously recorded, a "transient" can be observed due to the diffusion of the point defects in order to reach the new thermodynamic equilibrium population. Many works have been devoted to the majority point defects (non-stoichiometry). In this paper we present an overview about the high temperature transitory plastic deformation which is related with the minority point defects.
    Jin, Y., Kato, H., Korablova, I., Ioku, K., and Yamasaki, N.
    Effect of O2 on copper-water vapor interaction near critical point 2006 Journal of Materials Science
    Vol. 41(5), pp. 1571-1577 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;A significant weight loss of copper plate was observed after copper-water vapor interaction near critical point. This leads to the acceleration of the ceramic layer formation on SUS surface during granite-water vapor interaction in the presence of copper. In this paper, we have determined the chemical state of copper at which the mass transfer takes place through reaction with H2 and O2+N2 gas mixture at the different O2 amount. Obtained results indicate that the weight loss of copper plate occurs at Cu2O (+1) state due to a complex processes. The morphology of copper species on the surface of mesh and granite suggests that the Cu2O was dissolved in water vapor and recrystallized on the surface of mesh and granite. Copper species were characterized by X-ray diffraction(XRD), scanning electron microscopy (SEM) equipped with an energy dispersive X-ray (EDX).
    Johnsen, K. and Kavoulakis, G.M.
    Probing Bose-Einstein Condensation of Excitons with Electromagnetic Radiation 2001 Physical Review Letters
    Vol. 86(5), pp. 858-861 
    article DOI  
    Jolk, A. and Klingshirn, C.F.
    Linear and Nonlinear Excitonic Absorption and Photoluminescence Spectra in Cu2O: Line Shape Analysis and Exciton Drift 1998 Physica Status Solidi (b)
    Vol. 206(2), pp. 841-850 
    article DOI  
    Abstract: A complete analysis of the line shape of the excitonic absorption and photoluminescence lines of the yellow series of Cu2O is given. A detailed fit to the absorption lines up to the n = 5 exciton according to Toyozawa's theory gives precise values for the excitonic resonance energies, allowing to calculate the excitonic Rydberg. The fit to the photoluminescence lines shows very good agreement with experimental data at different temperatures. At high excitation, the fit to the excitonic absorption lines reveals the fundamental mechanism for bleaching of exciton absorption lines in Cu2O. Based on these findings, a new all-optical method for the observation of exciton transport in Cu2O is proposed.
    Jolk, A., Jörger, M., and Klingshirn, C.
    Exciton lifetime, Auger recombination, and exciton transport by calibrated differential absorption spectroscopy in Cu2O 2002 Physical Review B
    Vol. 65(24), pp. 245209 
    article DOI  
    Jörger, M., Schmidt, M., Jolk, A., Westphäling, R., and Klingshirn, C.
    Absolute external photoluminescence quantum efficiency of the $1s$ orthoexciton in Cu2O 2001 Physical Review B
    Vol. 64(11), pp. 113204 
    article DOI  
    Jörger, M., Fleck, T., Klingshirn, C., and von Baltz, R.
    Midinfrared properties of cuprous oxide: High-order lattice vibrations and intraexcitonic
    transitions of the $1s$ paraexciton
    2005 Physical Review B
    Vol. 71, pp. 235210 
    article DOI  
    Joseph, S. and Kamath, P.V.
    Electrodeposition of Cu2O Coatings on Stainless Steel Substrates 2007 Journal of the Electrochemical Society
    Vol. 154(7), pp. E102-E106 
    article DOI  
    Kalabin, M.M. and Sharavskii, P.V.
    Surface conductivity of cuprous-oxide rectifiers 1966 Soviet Physics Journal
    Vol. 9(5), pp. 79-83 
    article URL 
    Abstract: The physical nature of the surface conductivity of cuprous-oxide rectifiers, the existence of which was indicated by the authors (Fizika tverdogo tela,2, 857, 1960) is investigated. It is shown that this effect is not caused by surface conductivity of the cuprous oxide, but is due to the presence of a conduction channel along the edge of the p-n junction. The effect of humidity and the vapors of various liquids on the surface conductivity of rectifiers is investigated. The results obtained are discussed and a mechanism to explain the presence of a conduction channel at the p-n junction of cuprous-oxide rectifiers is suggested.
    Kale, S., Ogale, S., Shinde, S., Sahasrabuddhe, M., Kulkarni, V.N., Greene, R.L., and Venkatesan, T.
    Magnetism in cobalt--doped Cu2O thin films without and with Al, V, or Zn codopants 2003 Applied Physics Letters
    Vol. 82, pp. 2100-2102 
    article DOI  
    Kalingamudali, S.R.D. and Siripala, W.
    Observation of defect interface states at the Cu2O/Cu$_x$S junction using thermally stimulated I--V measurements 2001 Sri Lankan Journal of Physics
    Vol. 2, pp. 7-12 
    article URL 
    Abstract: A simple method was developed to fabricate a Cu2O/CuxS p-n junction diode and I-V characteristics of the diode was measured at various temperatures. It was revealed that there are current transport mechanisms at the junction which are leading to high voltage currents. Namely, an oscillatory behaviour of the current with the temperature was observed under reverse bias conditions. This behaviour was interpreted as the thermally enhanced tunneling at the junction due to the existence of defect interface states. We believe that proper surface treatment might reduce the density if interface states and thereby improve the I-V characteristics of the diode.
    Karpinska, K., van Loosdrecht, P.H.M., Handayani, I.P., and Revcolevschi, A.
    Para-excitons in Cu2O---a new approach 2005 Journal of Luminescence
    Vol. 112, pp. 17-20 
    article DOI  
    Karpinska, K., Mostovoy, M., van der Vegte, M.A., Revcolevschi, A., and van Loosdrecht, P.H.M.
    Decay and coherence of two-photon excited yellow orthoexcitons in Cu2O 2005 Physical Review B
    Vol. 72, pp. 155201 
    article DOI  
    Katayama, J., Ito, K., Matsuoka, M., and Tamaki, J.
    Performance of Cu2O/ZnO Solar Cell Prepared By Two-Step Electrodeposition 2004 Journal of Applied Electrochemistry
    Vol. 34(7), pp. 687-692 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;Cu2O/ZnO solar cells with improved performance were fabricated by an inexpensive two-step process. The process involves potentiostatic deposition of ZnO on NESA glass (tin-oxide-coated glass) followed by galvanostatic deposition of Cu2O to form Cu2O/ZnO/NESA solar cells with a short-circuit photocurrent density of 2.08 mA cm−2,an open-circuit voltage of 0.19 V, a fill factor of 0.295 and conversion efficiency of 0.117%. The performance of the solar cells thus prepared is discussed in terms of the laminated structure, construction of the heterojunction, and the crystallinity and optical properties of each semiconductor.
    Kaufman, R.G. and Hawkins, R.T.
    Defect Luminescence of Thin Films of Cu2O on Copper 1984 Journal of the Electrochemical Society
    Vol. 131, pp. 385-388 
    article DOI  
    Kaufman, R.G. and Hawkins, R.T.
    Vol. 31-32, pp. 509-511 
    article DOI  
    Kaufman, R.G. and Hawkins, R.T.
    Annealing of Copper and Oxygen Vacancies in Cuprous Oxide Films Monitored by Low Temperature Luminescence 1986 Journal of the Electrochemical Society
    Vol. 133, pp. 2652-2656 
    article DOI  
    Kaufman, R.G.
    Ohmic copper--cuprous oxide contacts 1986 (4582542)  patent  
    Kaufman, R.G. and Dickinson, C.D.
    Luminescence of Polycrystalline Cuprous Oxide Films on Copper Metal at $4K$ and the Effects of Stress 1988 Journal of the Electrochemical Society
    Vol. 135, pp. 2096-2098 
    article DOI  
    Kavoulakis, G.M., Chang, Y.-C., and Baym, G.
    Fine structure of excitons in Cu2O 1997 Physical Review B
    Vol. 55, pp. 7593-7599 
    article DOI  
    Kawazoe, H., Yasukawa, M., Hyodo, H., Kurita, M., Yanagi, H., and Hosono, H.
    P-type electrical conduction in transparent thin films of CuAlO2 1997 Nature
    Vol. 389(6654), pp. 939-942 
    article DOI  
    Keldysh, L.V. and Kozlov, A.N.
    Collective Properties of Large-Radius Excitons 1967 JETP Letters
    Vol. 5, pp. 190-194 
    article URL 
    Kennard, E.H. and Dieterich, E.O.
    An Effect of Light upon the Contact Potential of Selenium and Cuprous Oxide 1917 Physical Review
    Vol. 9, pp. 58-63 
    article DOI  
    Kenway, D.J., Duvvury, C., and Weichman, F.L.
    Evidence of a Competitive Phenomenon between the $0.72textmu m$ and $0.93textmu m$ Luminescences of Cu2O 1978 Journal of Luminescence
    Vol. 16, pp. 171-175 
    article DOI  
    Kikuchi, N. and Tonooka, K.
    Electrical and structural properties of Ni--doped Cu2O films prepared by pulsed laser deposition 2005 Thin Solid Films
    Vol. 486, pp. 33-37 
    article DOI  
    Kikuchi, N., Tonooka, K., and Kusano, E.
    Mechanisms of carrier generation and transport in Ni--doped Cu2O 2006 Vacuum
    Vol. 80, pp. 756-760 
    article DOI  
    Kim, J.Y., Hanson, J.C., Frenkel, A.I., Lee, P.L., and Rodriguez, J.A.
    Reaction of CuO with hydrogen studied by using synchrotron-based x-ray diffraction 2004 Journal of Physics: Condensed Matter
    Vol. 16(33), pp. S3479-S3484 
    article DOI  
    Abstract: CuO and Cu 2 O powders were reacted by hydrogen to study the reduction mechanism and the ionic states of Cu (Cu 2+ , Cu 1+ and Cu 0 ). The reduction behaviour and the existence of an intermediate state were investigated by using synchrotron-based high-resolution in situ x-ray diffraction (S-XRD) techniques. The results revealed that CuO directly reduces to metallic Cu ( ##IMG## [] mathrm Cu^2+ to mathrm Cu^0 ), under a normal flow of hydrogen. There was no hint of an intermediate state (Cu 1+ ) during the reduction. In certain conditions, however, an intermediate phase (Cu 2 O) appears under either very small flow of hydrogen (20 °C min −1 ), suggesting that the reduction kinetics strongly depends on reduction conditions.
    Kinoshita, A. and Nakano, T.
    Production of Cuprous Oxide Single Crystal by Melt 1966 Japanese Journal of Applied Physics
    Vol. 5(11), pp. 1121 
    article DOI  
    Kinoshita, A. and Nakano, T.
    Cu2O Crystal Growth by Hydrothermal Technique 1967 Japanese Journal of Applied Physics
    Vol. 6(5), pp. 656-657 
    article DOI  
    Kirsch, P.D. and Ekerdt, J.G.
    Chemical and thermal reduction of thin films of copper (II) oxide and copper (I) oxide 2001 Journal of Applied Physics
    Vol. 90, pp. 4256-4264 
    article DOI  
    Abstract: Chemical and thermal reduction of copper oxide thin films (~20 Å) has been studied with x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) for application in microelectronic device interconnects. XPS showed that copper (I) oxide (Cu2O) and copper (II) oxide (CuO) were reduced to copper metal at 400 K within a 30 min exposure to deuterium atoms (D*) and molecules at 1×10-4 Torr. Similarly, XPS showed that Cu2O was reduced to copper metal at 400 K within a 30 min exposure to methyl radicals (CH3*) and acetone molecules at 1×10-4 Torr. After D* exposure, TPD showed O leaves the Cu2O surface as D2O from 400 K to 700 K with a peak desorption temperature of 510 K. After CH3* exposure, TPD showed O leaves the Cu2O surface as CO2 over a range from 400 to 700 K with a peak temperature at 590 K. With carbon impurity below the XPS detection limit, thermal reduction of CuO to Cu2O was verified by XPS near 890 K. TPD experiments showed that O leaves the CuO surface as O2 at 890 K. Without surface C, thermal reduction of Cu2O was not observed up to 1073 K. Reduction of Cu2O without reactive radical species (D* or CH3*) was negligible. These results suggest that thin films of copper oxide can be reduced at 400 K with D* and CH3*.
    Kleinman, L. and Mednick, K.
    Self-consistent energy bands of Cu2O 1980 Phisical Review B
    Vol. 21, pp. 1549-1553 
    article DOI  
    Klier, E., Kužel, R., and Pastrňák, J.
    Влияние предварител ьного освещения на пр оводимость и фотопроводимость з акиси меди 1955 Czechoslovak Journal of Physics
    Vol. 5, pp. 421-424 
    article DOI  
    Klingshirn, C., Fleck, T., and Jörger, M.
    Some Considerations Concerning the Detection of Excitons by Field Ionization in a Schottky Barrier 2002 Physica Status Solidi (b)
    Vol. 234, pp. 23-25 
    article DOI  
    Klingshirn, C., Fleck, T., and Jörger, M.
    Response to ``Comment on `Some considerations concerning the detection of excitons by field ionization in a Schottky barrier' '' 2003 Physica Status Solidi (b)
    Vol. 239, pp. 261-264 
    article DOI  
    Klingshirn, C., Jörger, M., Fleck, T., and Jolk, A.
    Exciton transport in Cu2O, exciton detection by field ionization in a Schottky barrier and intraexcitonic transitions 2005 Solid State Communications
    Vol. 134, pp. 155-158 
    article DOI  
    Abstract: This contribution consists of several parts. In a first part we discuss transport measurements of excitons in Cu2O, their detection by spatially and temporally resolved pump-and-probe beam spectroscopy and by field ionization in a Schottky barrier; in the next one we report on transitions from the 1s para to the 2p para exciton state observed in visible pump-IR probe spectroscopy and finally we discuss qualitatively a phase diagram for bulk semiconductors including excitonic Bose Einstein condensation and the transition to an electron hole plasma.
    Knox, R.S.
    Theory of Excitons 1963   book  
    Kobayashi, H., Takahashi, M., Maida, O., Asano, A., Kubota, T., Ivančo, J., Nakajima, A., and Akimoto, K.
    Semiconductor surface and interface passivation by cyanide treatment 2004 Applied Surface Science
    Vol. 235, pp. 279-292 
    article DOI  
    Kobayashi, H., Nakamura, T., and Takahashi, N.
    Preparation of Cu2O films on MgO $(110)$ substrate by means of halide chemical vapor deposition under atmospheric pressure 2007 Materials Chemistry and Physics
    Vol. 106(2-3), pp. 292-295 
    article DOI  
    Abstract: High-quality Cu2O thin films were grown epitaxially on MgO (1�1�0) substrate by halide chemical vapor deposition under atmospheric pressure (AP-HCVD). The full width at half maximum of X-ray diffraction [omega] rocking measurement of the (2�2�0) plane was 0.1429� and that the of the (1�-1�0) plane was 0.303�.This result showed that the Cu2O films have a high degree of out-of-plane and in-plane crystallinity. Pole-figure and reciprocal space mapping (RSM) of Cu2O films showed Cu2O film is grown without strain. Optical band gap energy of Cu2O film calculated from absorption spectra showed 2.38�eV. These results indicated that AP-HCVD was promising growth method for high-quality Cu2O film.
    Komp, R.J. and Trivich, D.
    The Effect of Ion Bombardment on the Photoelectric Threshold of Single Crystal Cuprous Oxide 1966 Journal of the Electrochemical Society
    Vol. 113(7), pp. 702-706 
    article DOI  
    Kosenko, A. and Emel'chenko, G.
    Equilibrium phase relationships in the system Cu-O under high oxygen pressure 2001 Journal of Phase Equilibria
    Vol. 22(1), pp. 12-19 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;The equilibrium phase relationships near the liquidus line of the system Cu2O-CuO-O2 (a part of wider system Cu-O) were determined under pure oxygen pressure from 0.001 to 11 MPa by three experimental methods: differential thermal analysis (DTA), thermogravimetry (TG), and thermobarometry (TB). The coordinates of the eutectic point between solid Cu2O and CuO were found to be P
    Kosugi, T. and Kaneko, S.
    Novel Spray-Pyrolysis Deposition of Cuprous Oxide Thin Films 1998 Journal of the American Ceramic Society
    Vol. 81(12), pp. 3117-3124 
    article DOI  
    Abstract: Spray pyrolysis of aqueous solutions that include copper(II) acetate, glucose, and 2-propanol was studied for the formation of cuprous oxide (Cu2O) thin films on glass substrates. The deposition conditions, based on the phase relations of the films, were investigated in terms of solution concentration and substrate temperature. Also, the formation process was kinetically discussed. The Cu2O thin film obtained here was composed of rounded grains 223C50 nm in size with a surface roughness of 223C30 nm. This film was reddish yellow and showed indirect and direct bandgap energies of 1.95 and 2.60 eV, respectively. Furthermore, the film exhibited p-type conduction, with a resistivity of 223C100 Omegacm.
    Kotsyumakha, P.A. and Likhobabin, N.P.
    Parameters of alloy p-n junctions in Cu2O 1967 Russian Physics Journal
    Vol. 10(4), pp. 75-77 
    article DOI  
    Abstract: The p-n junctions are made by melting copper on single-crystal Cu2O plates. A change in specific resistance of the Cu2O from 2.8 × 102 to 1.15 × 105 ohm-cm causes the reverse voltage at a reverse-current density of 2 m A/cm2 to increase from 15 to 500 V, while the forward current density at 2 V decreases from 250 to 2 mA/cm2.
    Kotsyumakha, P.A. and Likhobabin, N.P.
    Cuprous oxide photoresistors 1968 Soviet Physics Journal
    Vol. 11(8), pp. 112-113 
    article DOI  
    Kotsyumakha, P.A. and Likhobabin, N.P.
    Space-charge limited currents in thin single-crystal layers of Cu2O 1968 Soviet Physics Journal
    Vol. 11(8), pp. 114-115 
    article DOI  
    Krishnamoorthy, P.K. and Sircar, S.C.
    Influence of Oxygen Pressure on the Oxidation Kinetics of Copper in Dry Air at Room Temperature 1969 Journal of the Electrochemical Society
    Vol. 116(6), pp. 734-736 
    article DOI  
    Kugel, G.E., Carabatos, C., and Kress, W.
    LATTICE DYNAMICS OF CUPRITE (Cu2O) 1981 Journal de Physique Colloques
    Vol. 42, pp. C6-884-C6-886 
    article DOI  
    Kunert, H. and Suffczynski, M.
    Vector-coupling coefficients for space groups based on simple cubic lattices 1980 Journal de Physique
    Vol. 41(11), pp. 1361-1370 
    article DOI  
    Kuo, C.-H. and Huang, M.H.
    Morphologically controlled synthesis of Cu2O nanocrystals and their properties 2010 Nano Today
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: Summary The ability to prepare inorganic nanocrystals with well-defined morphologies and sharp faces should facilitate the examination of their facet-dependent surface, catalytic, electrical, and other properties. In this review we cover different synthetic methods for the growth of Cu2O nanocrystals with morphological control. Cu2O nanocrystals with cubic, cuboctahedral, truncated octahedral, octahedral, and multipod structures have been prepared mainly by wet chemical, electrodeposition, and solvothermal synthesis methods. Methods used for the formation of hollow Cu2O nanocubes, octahedra, and truncated rhombic dodecahedra are also presented. Morphology of Cu2O nanocrystals can be expanded with the use of gold nanocrystal cores to guide the overgrowth of Cu2O shells. Surface properties of Cu2O nano- and microcrystals with sharp faces have been examined in a few studies. The 1�1�1 faces were found to interact well with negatively charged molecules, while the 1�0�0 faces are less sensitive to molecular charges. Preferential adsorption of sodium dodecyl sulfate molecules on the 1�1�1 faces of Cu2O crystals has been demonstrated via plane-selective deposition of gold nanoparticles on only the 1�0�0 faces. It is expected that the development of improved synthetic methods for Cu2O nanocrystals and more knowledge of their facet-dependent properties should lead to their applications in photoactivated energy conversion and catalysis.
    Kushida, T., Benedek, G.B., and Bloembergen, N.
    Dependence of the Pure Quadrupole Resonance Frequency on Pressure and Temperature 1956 Physical Review
    Vol. 104(5), pp. 1364-1377 
    article DOI  
    Kužel, R.
    Влияние предварител ьного освещения нa характеристики медн озакисных выпрямите лей 1958 Czechoslovak Journal of Physics
    Vol. 8(1), pp. 81-89 
    article DOI  
    Abstract: ????????, ??? ??? ???? ?????? ???????????? ? ???????????? ?? ??????????? ~150°? ???? ?????? ?? ?????? ???? ??? ??????????? ????, ?? ? ??????????? ? ?????????? ? ???? ?? ??. ??? ????????? ??-?? ?????? ??????????? ?????? ? ?????? ? ??????????? ? ?????????? ? ?????????? ???? ??? ???? ?????????? ?? ?? ????? ??????????. ??????????????? ??? ??????? ? ?????????? ? ???????????? ????? ? ???????????? ????? ?? ?????? ?? ?? ?????? ??????? ??????????? ?-??. ??????????????? ??? ??????? ??????????? ?? ???????????? ?????????? ??????? ? ?? ? ?????? ????????? ?? ? ?????? ????????? ???????????. ??? ???? ??? ????? ????????? ? ????????????? ?????????? ? ??????? ???? ????????? ???? (? ???????? ???? ????? ????? ????).
    Kužel, R.
    The Effect of Pre-Illumination on the Characteristics of Cuprous Oxide Rectifiers 1958 Czechoslovak Journal of Physics
    Vol. 8, pp. 89 
    article DOI  
    Kužel, R.
    The Effect of Oxygen on the Electric Conductivity of a Cuprous Oxide Single Crystal 1961 Czechoslovak Journal of Physics
    Vol. 11(2), pp. 133-140 
    article DOI  
    Kužel, R.
    1961 Direct Current (ISSN: 0419-1803)
    Vol. 6, pp. 172 
    Kužel, R.
    The Influence of Pre-Illumination on the Work Function of Cuprous Oxide 1965 Czechoslovak Journal of Physics
    Vol. 15, pp. 709-717 
    article DOI  
    Kužel, R.
    1967 Acta Universitatis Carolinae. Mathematica et Physica
    Vol. 2, pp. 15 
    article URL 
    Kužel, R.
    1968 Proceedings of Second Cuprite Colloquium, University of Alberta, Edmonton, Canada, pp. Paper B  inproceedings  
    Kužel, R. and Weichman, F.L.
    Surface and Bulk Conductivities of Cu2O Single Crystals 1970 Journal of Applied Physics
    Vol. 41, pp. 271-279 
    article DOI  
    Kužel, R. and Weichman, F.L.
    Hole Mobility in Cu2O. I. Scattering by Lattice Vibrations 1970 Canadian Journal of Physics
    Vol. 48, pp. 2643-2656 
    article URL 
    Kužel, R., Cann, C.D., Sheinin, S.S., and Weichman, F.L.
    Hole Mobility in Cu2O. II. Scattering by Defects 1970 Canadian Journal of Physics
    Vol. 48, pp. 2657-2660 
    article URL 
    Lange, B.
    Photoelements and their applications 1938   book URL 
    Laskowski, R., Blaha, P., and Schwarz, K.
    Charge distribution and chemical bonding in Cu2O 2003 Physical Review B
    Vol. 67(7), pp. 075102 
    article DOI  
    Abstract: We have applied the augmented plane-wave plus local-orbitals method to investigate the charge density of Cu2O by means of Bader’s topological analysis and electric-field gradients (EFGs). It is rather clear that a simple Cu+-O2- model is inadequate for the explanation of bonding properties of Cu2O. Appearance of s-d hybridization in this system has been pointed out already in the literature. However, the amount of charge transferred from d to s Cu orbitals is overestimated by both the local-density approximation (LDA) and the generalized gradient approximation. As a result, the calculated EFG is underestimated by about 50% compared to experiment. Also the topological analysis of calculated densities suggests that density-functional theory overestimates the covalency of the Cu-O bond. In order to demonstrate the role of s-d hybridization as the main reason for the mentioned discrepancies, we have utilized artificially modified basis sets. Removing part of the 4s Cu character from the wave function increases the absolute EFGs and decreases the calculated bulk modulus, both resulting in better agreement with experiment. This is a result of an increased Cu d occupation and consequently a decreased asphericity of the d charge distribution. A more physical description of the localized nature of the 3d orbitals should be given by the LDA+U correction. We find that LDA+U “self-interaction corrected” (SIC) by Anisimov et al. [V.I. Anisimov, I.V. Solovyev, M.A. Korotin, M.T. Czyżyk, and G.A. Sawatzky, Phys. Rev. B 48, 16 929 (1993)] leads to EFGs in good agreement with experiment while LDA+U “around mean field” Cyżyk and Sawatzky [Phys. Rev. B 49, 14 211 (1994)] even worsens the results. This is to be expected according to the analysis given above, which indicates that the on-site correlations are important but are implemented only in the LDA+U (SIC) method.
    Leblanc, P.J. and Fortin, E.
    Evidence of lateral contraction of a travelling exciton packet 2005 Solid State Communications
    Vol. 134, pp. 151-154 
    article DOI  
    Abstract: A high density exciton packet travelling in Cu2O is spatially probed in a transverse direction. A lateral contraction is observed in the profile during the propagation process.
    Lee, S.Y., Mettlach, N., Nguyen, N., Sun, Y.M., and White, J.M.
    Copper oxide reduction through vacuum annealing 2003 Applied Surface Science
    Vol. 206(1-4), pp. 102-109 
    article DOI  
    Abstract: The reduction of partially- and fully-oxidized Cu films was carried out by vacuum annealing, and the reduction mechanisms were investigated in situ by XPS. For a partially-oxidized Cu film, CuO was reduced to Cu2O around 380�K, and the Cu2O concentration decreased with increasing annealing temperature and fell below the XPS detection limit at 673�K. For a fully-oxidized Cu film, CuO started to form Cu2O around 473�K, and Cu began to appear at 673�K. The results for a partially-oxidized film are interpreted in terms of oxygen diffusion into bulk Cu rather than oxygen desorption into vacuum.
    Lefez, B. and Lenglet, M.
    Photoluminescence of thin oxide layers on metallic substrates (Cu2O/Cu and ZnO/Zn) 1991 Chemical Physics Letters
    Vol. 179(3), pp. 223-226 
    article DOI  
    Abstract: Photoluminescence of zinc and copper oxide layers is studied. The results obtained, emission and excitation spectra, with oxide layers (thickness [less-than-or-equals, slant]1 [mu]) are similar to reported photoluminescence from large layers and single crystals. Models for the centers responsible for the emission are proposed.
    Lefez, B., Kartouni, K., Lenglet, M., Rönnow, D., and Ribbing, C.G.
    Application of reflectance spectrophotometry to the study of copper (I) oxides (Cu2O and Cu$_3$O2) on metallic substrate 1994 Surface and Interface Analysis
    Vol. 22(1-12), pp. 451-455 
    article DOI  
    Abstract: The aim of this study is to characterize the compounds grown on copper during the oxidation at low temperature (T &lt; 523 K) by optical methods: photoluminescence and UV-Visible-NIR diffuse reflectance spectroscopy. Two cuprous oxides Cu2O and Cu3O2 have been studied. The absorption of Cu2O films in the range 450-630 nm is mainly due to non-stoichiometry bands associated with copper and oxygen vacancies. Cu3O2 is characterized by an optical band gap greater than that of Cu2O (respectively 2.25 and 1.95 eV) and by an intense luminescence emission at 760-780 nm. Cu3O2 may be considered as a gross defect structure of Cu2O (aCu2O = 0.427 nm, aCu3O2 = 0.431 nm). The experimental approach of the oxidation mechanism reveals that at 423 K Cu2O is the primary product which later on is transformed into Cu3O2. Experimental and calculated optical absorption curves disclose the nucleation of CuO inside the cuprous oxides layer for oxidation in the range 473-523 K.
    Lenglet, M., Kartouni, K., and Delahaye, D.
    Characterization of copper oxidation by linear potential sweep voltammetry and UV-Visible-NIR diffuse reflectance spectroscopy 1991 Journal of Applied Electrochemistry
    Vol. 21(8), pp. 697-702 
    article DOI  
    Abstract: The aim of this study was to characterize the compounds grown on copper during oxidation at low temperature (TxO of mixed valency character, a non stoichiometric cuprous oxide, CuO and its precursor. The mechanism of reduction has been established for layers containing CuO and a non stoichiometric copper(I) oxide. CuO is reduced before cuprous oxide. In complicated cases, it is impossible to draw conclusions from the characteristics of the electrochemical reduction (the first step of CuO reduction and the reduction of Cu(I) species specific of the non-stoichiometry are observed at the same potential). Nevertheless, the association of a non-destructive technique such as diffuse reflectance spectroscopy and electrochemical methods allows identification of the different species present in corrosion layers on copper surfaces.
    Lenglet, M., Kartouni, K., Machefert, J., Claude, J.M., Steinmetz, P., Beauprez, E., Heinrich, J., and Celati, N.
    Low temperature oxidation of copper: The formation of CuO 1995 Materials Research Bulletin
    Vol. 30(4), pp. 393-403 
    article DOI  
    Abstract: The study of the early stages of low temperature copper oxidation reveals unambiguously a fast process of Cu to Cu3O2 and a slow process for the formation of CuO and demonstrates the mechanism of nucleation of CuO as a result of the aggregation of vacancies internally in cuprous oxides.
    Li, J., Wang, S.Q., Mayer, J.W., and Tu, K.N.
    Oxygen-diffusion-induced phase boundary migration in copper oxide thin films 1989 Physical Review B
    Vol. 39, pp. 12367-12370 
    article DOI  
    Abstract: The transition of copper oxide thin films from CuO to Cu2O during vacuum annealing has been studied by transmission electron microscopy and Rutherford backscattering spectroscopy. Dark field images show that isolated and large Cu2O grains emerge from the small CuO grain matrix. The abrupt change in oxygen concentration across the phase boundary between CuO and Cu2O in the reaction is different from the continuous change of δ in oxidation and reduction of the superconducting YBa2Cu3O7-δ oxide. The growth of Cu2O grains is linear with time and has an activation energy of 1.1 eV. We propose that the discontinuous morphology of grain growth of Cu2O is due to the migration of the Cu2O-CuO phase boundary induced by oxygen out diffusion along the moving phase boundary.
    Li, J., Vizkelethy, G., Revesz, P., Mayer, J.W., and Tu, K.N.
    Oxidation and reduction of copper oxide thin films 1991 Journal of Applied Physics
    Vol. 69(2), pp. 1020-1029 
    article DOI  
    Li, Y. and Hess, D.W.
    Transport Considerations in the Plasma-Assisted Oxidation of Copper Films 2004 Journal of the Electrochemical Society
    Vol. 151(1), pp. G40-G46 
    article DOI  
    Li, X., Tao, F., Jiang, Y., and Xu, Z.
    3-D ordered macroporous cuprous oxide: Fabrication, optical, and photoelectrochemical properties 2007 Journal of Colloid and Interface Science
    Vol. 308(2), pp. 460-465 
    article DOI  
    Abstract: Cuprous oxide 3-D ordered macroporous material was constructed by electrochemical deposition using a polystyrene colloidal crystal as template. The highly ordered macroporous structure with a hexagonal array can be extended over hundreds of square micrometers. The photonic stop bands of both the PS colloidal crystal and Cu2O 3DOM were found. Due to the highly ordered porous structure, the optical absorption and the charge carrier transportation are better in Cu2O 3DOM than in bulk Cu2O, which makes the reduction of oxygen faster on Cu2O 3DOM than on bulk Cu2O under visible light illumination. The higher photocurrent efficiency under visible light illumination makes the 3DOM Cu2O more suitable for solar applications.
    Li, B.S., Akimoto, K., and Shen, A.
    Growth of Cu2O thin films with high hole mobility by introducing a low-temperature buffer layer 2009 Journal of Crystal Growth
    Vol. 311, pp. 1102-1105 
    article DOI  
    Likhobabin, N.P., Shestatskii, S.N., Sobolev, V.V., and Volovenko, L.V.
    Electroabsorption in the Yellow Exciton Series of Cuprous Oxide in a Wide Range of Modulating Fields 1970 Physica Status Solidi (b)
    Vol. 40(2), pp. K45-K49 
    article DOI  
    Likhobabin, N.P.
    Temperature dependence of the space-charge limited current in cuprous oxide 1971 Russian Physics Journal
    Vol. 14(2), pp. 269-270 
    article URL 
    Lin, J.L. and Wolfe, J.P.
    Bose-Einstein condensation of paraexcitons in stressed Cu2O 1993 Physical Review Letters
    Vol. 71(8), pp. 1222-1225 
    article DOI  
    Liu, R., Bohannan, E.W., Switzer, J.A., Oba, F., and Ernst, F.
    Epitaxial electrodeposition of Cu2O films onto InP(001) 2003 Applied Physics Letters
    Vol. 83, pp. 1944-1946 
    article DOI  
    Abstract: Cu2O (cuprite) films were deposited electrochemically onto InP (001) single-crystal substrates from aqueous solutions at room temperature. X-ray diffraction indicates a unique epitaxial 45°[001] orientation relationship between Cu2O and InP. This reduces the mismatch between corresponding spacings to 2.9%, compared with a mismatch of 27.2% between the lattice parameters of Cu2O and InP. The morphology of the Cu2O film can be influenced via the electrolyte acidity. At a pH of 9.0, Cu2O forms pyramidal islands. At a pH of 12.0, on the other hand, cubelike morphologies of Cu2O are observed. Between a pH of 9.0 and 12.0, the direction of slowest growth changes from <111> to <100>. In apparent contradiction to the observation of a unique epitaxial orientation relationship, transmission electron microscopy reveals an amorphous oxygen-rich interlayer between the Cu2O and the InP crystal.
    Liu, Y.
    Excitons at high density in Cuprous Oxide and coupled quantum wells 2004 , pp. -School: University of Pittsburgh  phdthesis URL 
    Abstract: There is a 40-year long history in the search for Bose-Einstein condensation (BEC) of excitons in semiconductors. This thesis presents research directed toward this goal in bulk crystal Cu2O in three dimensions and in GaAs-based coupled quantum wells (CQW) in two dimensions. The Auger recombination process in Cu2O plays a major role in limiting the density of the excitons. We find that the rate for this process increases with applied stress and lattice temperature. We create paraexcitons in Cu2O through a resonant two-photon excitation in a harmonic potential trap with the Auger recombination process as small as possible (at low temperature and low stress), and find that the exciton creation efficiency in the resonant two-photon excitation is greater for one-beam excitation than for two colliding pulses, but the colliding pulse method may be useful for direct creation of a condensate in the ground state. The paraexciton density in this work is about thirty times less than the required density for BEC of paraexcitons. One promising direction for BEC of excitons in Cu2O is that with higher laser power from stronger IR laser sources, or at lower temperature, the critical density can be approached under one-beam two-photon excitation resonant with the paraexciton state. In two dimensions, the CQW structure has been modified with four design strategies: highest possible barriers, introducing into the barriers a superlattice of 60 angstrom GaAs wells, p-i-n doping, and wider quantum wells, which provides indirect excitons low disorder and high mobility. With a cold near-resonant excitation, we conclude that the excitons act as a free gas, travelling distances of hundreds of microns. We also present observations of a narrow beam of emitted light, when the indirect excitons are confined in a two-dimensional harmonic potential trap, in a way quite similar to the first observations of BEC in alkali atoms. A beam-like emission has been suggested as a telltale for BEC of excitons. This opens the door to a whole range of investigations, including attempts to observe coherence of the emitted light, proof of superfludity of the excitons, and other fascinating effects.
    Liu, Y.L., Harrington, S., Yates, K.A., Wei, M., Blamire, M.G., MacManus-Driscoll, J.L., and Liu, Y.C.
    Epitaxial, ferromagnetic Cu$_2-x$Mn$_x$O films on (001) Si by near-room-temperature electrodeposition 2005 Applied Physics Letters
    Vol. 87, pp. 222108 
    article DOI  
    Liu, Y.L., Liu, Y.C., Mu, R., Yang, H., Shao, C.L., Zhang, J.Y., Lu, Y.M., Shen, D.Z., and Fan, X.W.
    The structural and optical properties of Cu2O films electrodeposited on different substrates 2005 Semiconductor Science Technology
    Vol. 20, pp. 44-49 
    article DOI  
    Abstract: Cuprous oxide films were successfully electrodeposited onto three different substrates through the reduction of copper lactate in alkaline solution at pH = 10. The substrates include indium tin oxide film coated glass, n-Si wafer with (001) orientation and Au film evaporated onto Si substrate. The substrate effects on the structural and optical properties of the electrodeposited films are investigated by in situ voltammetry, current versus time transient measurement, ex situ x-ray diffraction, scanning electron microscopy, UV–vis transmittance and reflectance and photoluminescence techniques. The results indicate that the choice of substrate can strongly affect the film morphology, structure and optical properties.
    Liu, Y. and Snoke, D.
    Resonant two-photon excitation of $1s$ paraexcitons in cuprous oxide 2005 Solid State Communications
    Vol. 134(1-2), pp. 159-164 
    article DOI  
    Abstract: We have created paraexcitons in Cu2O via resonant two-photon generation, and examined their population dynamics by means of time-correlated single photon detection. Confining the excitons to a constant volume in a harmonic-potential trap made with inhomogeneous applied stress along the [001] axis, we find that paraexcitons are created directly, and orthoexcitons appear primarily through a up-conversion of the paraexcitons. Also we generate excitons with two colliding pulses, and the luminescence is weaker than that from one beam excitation with same total laser power. These results show that resonant one-beam two-photon generation of paraexcitons is a promising way to pursue Bose-Einstein condensation of paraexcitons.
    Liu, Y. and Snoke, D.
    Temperature dependence of exciton Auger decay process in cuprous oxide 2006 Solid State Communications
    Vol. 140, pp. 208-213 
    article DOI  
    Abstract: We report a theoretical and experimental study on Auger decay of excitons in Cu2O at a wide range of temperatures, from 2 to 325 K, in single-photon surface excitation. We find that the Auger constant linearly increases with temperature above 100 K. This constant is important for experiments on Bose condensation of excitons.
    Loison, J.L., Robino, M., and Schwab, C.
    Progress in Melt growth of Cu2O 1980 Journal of Crystal Growth
    Vol. 50, pp. 816-822 
    article DOI  
    Lu, F.-H., Fang, F.-X., and Chen, Y.-S.
    Eutectic reaction between copper oxide and titanium dioxide 2001 Journal of the European Ceramic Society
    Vol. 21(8), pp. 1093-1099 
    article DOI  
    Abstract: Eutectic reaction between copper oxide (CuO) and titanium dioxide (TiO2) was investigated by using directly Cu and TiO2 samples and by employing optical microscopy, X-ray diffraction (XRD), scanning electron microscopy, and electron probe for microanalysis (EPMA). Different types of samples including Cu plate/TiO2 pellet samples and TiO2/Cu/TiO2 sandwiched samples were prepared. The samples would react with each other at as considerably low as about 900�C in air, which is due to a eutectic reaction. The reaction diagram was generated, in which different reaction categories were denoted at various temperatures (300-1070�C) and times. After annealing, the weight changes normalized to the original Cu samples were also analyzed to verify the eutectic reaction. The eutectic was identified to be the CuO-TiO2 system characterized from XRD and EPMA analyses. Annealing in N2/O2=9 at the same temperature as in air resulted in similar but not so drastic eutectic melting phenomena. The eutectic reaction would enhance significantly the grain growth of TiO2 and the oxidation of Cu. The changes in the microstructures and the morphologies of the samples were also investigated. The eutectic temperatures of CuO and other oxide systems were compared and discussed. The eutectic points as well as the phase diagram of the CuO-TiO2 system were calculated and analyzed. Several potential applications of the reactions were also proposed.
    Lu, Y.-M., Chen, C.-Y., and Lin, M.H.
    Effect of hydrogen plasma treatment on the electrical properties of sputtered N-doped cuprous oxide films 2005 Thin Solid Films
    Vol. 480-481, pp. 482-485 
    article DOI  
    Lu, Y.-M., Chen, C.-Y., and Lin, M.H.
    Effect of hydrogen plasma treatment on the electrical properties of sputtered N-doped cuprous oxide films 2005 Materials Science and Engineering B
    Vol. 118(1-3), pp. 179-182 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) is a direct-gap semiconductor with band-gap energy of 2.0 eV and is regarded as one of the most promising materials for application in photovoltaic cells. Practical application has not been achieved to date because of the difficulty of controlling its electrical properties such as reducing the resistivity. It is known that nitrogen doping is one of the effective methods to reduce the resistivity of cuprous oxide films. In this study, N-doped cuprous oxide films have been deposited onto Corning 1737 at a constant substrate temperature of 350 °C using a magnetron co-sputtering process in a mixture of oxygen and argon gases. It was found that the hole carrier concentration of nitrogen-doped cuprous oxide films increased from 9.0 × 1017 cm-3 to 4.0 × 1018 cm-3 as the nitrogen flow rate increased from 4 to 12 ml min-1. The lowest resistivity of Cu2O film doped with nitrogen obtained in this study was 14.8 [Omega] cm and further downed to a value of 9.1 [Omega] cm after 1 min of hydrogen plasma treatment. Because the mobility of the carrier is almost constant, it is believed that the hydrogen plasma treatment may terminate the dangling bonds of Cu and result in increasing the carrier concentration which leads to decrease in the resistivity of the Cu2O films.
    Lu, H.-C., Chu, C.-L., Lai, C.-Y., and Wang, Y.-H.
    Property variations of direct-current reactive magnetron sputtered copper oxide thin films deposited at different oxygen partial pressures 2009 Thin Solid Films
    Vol. 517, pp. 4408-4412 
    article DOI  
    Lupu, A.
    Thermogravimetry of copper and copper oxides (Cu2O-CuO) 1970 Journal of Thermal Analysis and Calorimetry
    Vol. 2(4), pp. 445-458 
    article DOI  
    Abstract: The thermogravimetry of mixtures of metallic copper and copper oxides was studied. The experiments were performed by heating the samples in air to 700–800° to transform all the components to copper(II) oxide, and continuing the heating in nitrogen to 1050–1100° when the dissociation of copper(II) oxide to copper(I) oxide is complete. The identification of the components and their quantitative determination were carried out by determining the shape, size, and ratio of the segments of the curves obtained during the heating. The method can be used for quantitative analysis of mixtures of copper and/or copper oxides.
    Ma, L., Peng, M., Li, J., Yu, Y., and Chen, Z.
    Cu2O nanorods with large surface area for photodegradation of organic pollutant under visible light 2007 Proceedings of the 7th IEEE Conference on Nanotechnology IEEE-NANO 2007, pp. 975-978  inproceedings DOI  
    Abstract: Cu2O nanorods with extraordinary large surface area are synthesized by polyol method successfully. Their photocatalytic property is evaluated by the photodegradation of brilliant red dye under visible light irradiation. For comparison, Cu2O nanocubes are synthesized and evaluated with photocatalytic property as well. The results show that the photocatalytic activity of the Cu2O nanorods is more than one time higher than that for Cu2O nanocubes under visible light. Additionally, the structure of the Cu2O nanorods is very stable and they can not be oxidized to CuO even during the photocatalytic reaction process. It is noticeable that this kind of Cu2O nanorods has remarkable large surface areas 47.6 m2/g, which is about forty times as large as that for as-prepared Cu2O nanocubes and it is also three times larger than that for the reported porous Cu2O nanoparticles. The large surface area of Cu2O nanorods leads to its higher adsorption ability to the brilliant red dye and excellent high photocatalytic activity under visible light. Since Cu2O nanorods are very stable and have high photocatalytic activity under visible light, they are expected to be used in photocatalytic oxidation technology practically in the future.
    Ma, M.-G. and Zhu, Y.-J.
    Hydrothermal synthesis of cuprous oxide microstructures assembled from needles 2008 Journal of Alloys and Compounds
    Vol. 455(1-2), pp. L15-L18 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) has been successfully synthesized by a hydrothermal method at 200 °C for 2 h using Cu(CH3COO)2·H2O, glycine (C2H5NO2) and NaOH. The morphology of Cu2O is significantly influenced by the concentration of glycine or NaOH.
    Macfarlane, R.
    Optical Stark spectroscopy of solids 2007 Journal of Luminescence
    Vol. 125, pp. 156-174 
    article DOI  
    Abstract: Not Available
    Madelung, O. and others
    Cuprous oxide (Cu2O) crystal structure, lattice parameters 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) optical properties 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) dielectric constant 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) magnetic properties 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) Debye temperature, density, melting point 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) diffusion coefficients 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) band structure, band energies 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) effective masses 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) excitons 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) phonon dispersion, phonon frequencies 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) sound velocities, elastic moduli 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) Young's and shear moduli, compressibility 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) thermal expansion, Grüneisen parameter 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Madelung, O. and others
    Cuprous oxide (Cu2O) transport properties 1998 Landolt-Börnstein
    Vol. III/41c 
    incollection DOI  
    Mahalingam, T., Chitra, J.S.P., Rajendran, S., Jayachandran, M., and Chockalingam, M.J.
    Galvanostatic deposition and characterization of cuprous oxide thin films 2000 Journal of Crystal Growth
    Vol. 216(1-4), pp. 304-310 
    article DOI  
    Abstract: Electrochemical deposition of cuprous oxide (Cu2O) thin films on tin-oxide-coated glass and copper substrates by cathodic reduction of alkaline cupric lactate solution has been investigated between 60 and 80°C. Deposition kinetics of cuprous oxide thin films were studied and the parameters limit for the deposition of the films were determined. Structure of the deposited film is simple cubic with a preferential orientation of (2 0 0). Optical absorption studies reveal 1.99 eV for band gap and optical constants (n,k) are evaluated. Electrical resistivity studies are carried out in the temperature range 27-330°C. The effect of annealing on the resistivity of Cu2O films are also studied and the results are discussed.
    Mahalingam, T., Chitra, J.S.P., Rajendran, S., and Sebastian, P.J.
    Potentiostatic deposition and characterization of Cu2O thin films 2002 Semiconductor Science and Technology
    Vol. 17, pp. 565-569 
    article DOI  
    Abstract: Semiconducting Cu2O thin films were electrodeposited potentiostatically on Cu and SnO2 substrates. The deposition kinetics of film growth and the conditions to obtain spotty and uniform Cu2O films are studied. X-ray diffraction studies revealed the formation of single phase cubic Cu2O films. The effects of deposition potential, solution pH and bath temperature on the structure are studied. The optical, electrical, composition and morphological analysis are carried out for Cu2O films prepared at various deposition conditions and the results are discussed.
    Mahalingam, T., Chitra, J.S.P., Chu, J.P., Velumani, S., and Sebastian, P.J.
    Structural and annealing studies of potentiostatically deposited Cu2O thin films 2005 Solar Energy Materials and Solar CellsInternational Symposium on Solar-Hydrogen-Fuel Cell
    Vol. 88(2), pp. 209-216 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) thin films were deposited on Cu and tin oxide coated glass substrates through potentiostatic electrodeposition. The optimum range of deposition parameters was experimentally investigated. X-ray diffraction studies revealed the formation of single-phase cubic Cu2O films in the deposition potential range from -0.355 to -0.555�V versus SCE. Studies revealed that an optimum pH of 9.0 yielded single-phase cubic films with improved crystallinity. The preferential orientation of (2�0�0) cubic Cu2O peak was found to increase with bath temperature in the range 30-70��C. The effects of annealing on the preferred orientation, grain size and optical band gap were studied. The energy conversion efficiencies of as-deposited and annealed p-Cu2O films as photocathodes in photoelectrochemical (PEC) solar cells were studied and the results were discussed.
    Mahalingam, T., Chitra, J., Chu, J., Moon, H., Kwon, H., and Kim, Y.
    Photoelectrochemical solar cell studies on electroplated cuprous oxide thin films 2006 Journal of Materials Science: Materials in Electronics
    Vol. 17(7), pp. 519-523 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;Cuprous oxide (Cu2O) is an interesting p-type semiconductor with a band gap of 2 eV suitable for solar cell applications. Deposition of Cu2O thin films by electrodeposition from aqueous solutions is a low temperature and inexpensive technique. in the present work, Cu2O thin films were cathodically deposited on Cu and tin oxide coated glass substrates by the cathodic reduction of copper (II) lactate solution. The optimized deposition conditions to synthesize cuprous oxide thin films were experimentally identified as; Deposition potential: −0.555 V versus SCE, pH: 9.0 0.1, Bath temperature: 70∘C. X-ray diffraction studies revealed the formation of single phase cubic Cu2O films. The effect of annealing on the structure and morphology of Cu2O thin films are studied. The dielectric susceptibility, optical conductivity and packing density are evaluated. Photoelectrochemical solar cells based on p-Cu2O films are constructed. Spectral response studies indicate a peak in photo current density around 600 nm corresponding to the band gap of Cu2O thin films. The effects of annealing, chemical etching and photo etching on the solar cell parameters are studied.
    Maier, G.
    Exzitonspektren von Mischkristallen 1960 Zeitschrift für Physik A Hadrons and Nuclei
    Vol. 160(5), pp. 527-534 
    article DOI  
    Abstract: Zusammenfassung Die Absorptionslinien des Kupferoxyduls konnten auch bei Mischkristallen mit Silberzusatz nachgewiesen werden. Es verschiebt sich die Seriengrenze kontinuierlich mit wachsendem Zusatz in Richtung größerer Wellenlängen. Die Rydberg-Konstante ändert sich dabei nicht. Aus Verbreiterung und Verschiebung der Linien kann auf Grund einer statistischen Überlegung eine Abschätzung der Größe der Kristallbereiche vorgenommen werden, die die relative Lage der Exzitonterme zum Valenzband bestimmen.
    Maluenda, J., Farhi, R., and Petot-Ervas, G.
    Chemical Diffusion Measurements In Single Crystalline Cuprous Oxide 1981 Journal of Physics and Chemistry of Solids
    Vol. 42, pp. 697-699 
    article DOI  
    Maluenda, J., Farhi, R., and Petot-Ervas, G.
    Electrical Conductivity At High Temperature And Thermodynamic Study Of Point Defects In Single Crystalline Cuprous Oxide 1981 Journal of Physics and Chemistry of Solids
    Vol. 42, pp. 911-921 
    article DOI  
    Manghnani, M.H., Brower, W.S., and Parker, H.S.
    Anomalous elastic behavior in Cu2O under pressure 1974 Physica Status Solidi (a)
    Vol. 25(1), pp. 69-76 
    article DOI  
    Abstract: The elastic constants Cij of single-crystal Cu2O measured to 3 kbar show linear variation with pressure. The best-fit values of the Cij and dCij/dP are: C11 = 1228.8, C44 = 121.0, Cprime = (C11-C12)/2 = 81.9 kbar, dC11/dP = 3.62, dC44/dP = -0.69, and dCprime/dP = -0.63, respectively. The elastic behavior of Cu2O is found to be anomalous in that dC44/dP and dCprime/dP are both negative, and dmu/dP, where mu is the isotropic shear modulus, is significantly negative (-0.67). This anomalous behavior suggests an instability of crystal structure. The high- and low-temperature limiting values of Gr�neisen gamma, gammaH and gammaL, computed from the dCij/dP are -1.98 and -3.59, respectively. The value of gammaH is in fairly good agreement with the reported Gr�neisen gamma value based on the nuclear quadrupole relaxation data. The negative Gr�neisen gamma values are consistent with the observed negative thermal expansion. The implication of gammaL being appreciable more negative than gammaH is that the coefficient of thermal expansion of Cu2O should become more negative at low temperatures.
    Marksteiner, P., Blaha, P., and Schwarz, K.
    Electronic structure and binding mechanism of Cu2O 1986 Zeitschrift für Physik B Condensed Matter
    Vol. 64(2), pp. 119-127 
    article DOI  
    Abstract: A self-consistent LAPW band structure calculation of Cu2O is presented. Total and partial densities of states and electron densities were calculated and are used to give an interpretation of chemical bonding. It is found that there are significant deviations from a simple ionic picture due to a depletion of the valence band of Cu-3d electrons leading to a non-spherical charge density around Cu. A critical discussion of theoretical and experimental work on Cu2O is given.
    Markworth, P.R., Chang, R.P.H., Sun, Y., Wong, G.K., and Ketterson, J.B.
    Epitaxial stabilization of orthorhombic cuprous oxide films on MgO(110) 2001 Journal of Materials Research
    Vol. 16, pp. 914-921 
    article DOI  
    Abstract: Not Available
    Martinez-Clemente, M. and Schmidt-Whitley, R.D.
    A TEM study of precipitates in Cu2O 1975 Journal of Materials Science
    Vol. 10(3), pp. 543-546 
    article DOI  
    Martinez-Clemente, M., Bretheau, T., and Castaing, J.
    Systèmes de glissement au cours de la déformation plastique de Cu2O 1976 Journal de Physique
    Vol. 37(7-8), pp. 895-899 
    article DOI  
    Martínez-Ruiz, A., Guadalupe Moreno, M., and Takeuchi, N.
    First principles calculations of the electronic properties of bulk Cu2O, clean and doped with Ag, Ni, and Zn 2003 Solid State Sciences
    Vol. 5, pp. 291-295 
    article DOI  
    Masumi, T.
    Dielectric Anomalies and Photoconductivity in Host Insulator Cu2O Correlative with High-$T_c$ Superconductivity 1991 Journal of the Physical Society of Japan
    Vol. 60(11), pp. 3625-3628 
    article DOI  
    Taizo, M. and Hiroshi, S.
    Nonlinear Optical Phenomena in Cyclotron Resonance of Positive Holes and Electrons in Cu2O 1991 Journal of the Physical Society of Japan
    Vol. 60(11), pp. 3629-3632 
    article DOI  
    Taizo, M. and Hiroshi, S.
    An Observation of Quantized Series of Step or Clew Temperatures in Superconductive-Conjugate Photoconductivity of Cu2O 1991 Journal of the Physical Society of Japan
    Vol. 60(11), pp. 3633-3636 
    article DOI  
    Mateen, A.
    Some Methodologies used for the Synthesis of Cuprous Oxide: A Review 2008 Journal of The Pakistan Materials Society
    Vol. 2(1), pp. 40-43 
    article URL 
    Mathew, X., Mathews, N.R., and Sebastian, P.J.
    Temperature dependence of the optical transitions in electrodeposited Cu2O thin films 2001 Solar Energy Materials and Solar Cells
    Vol. 70(3), pp. 277-286 
    article DOI  
    Abstract: Cu2O films on flexible copper and molybdenum (Mo) substrates were prepared by electrodeposition form an alkaline bath. The as-deposited films were p-type and the XRD analysis revealed that the film contains only the Cu2O phase. The thickness of the films was calculated from the interference fringes in the reflection spectra. The Au/Cu2O Schottky diodes were prepared by sputtering a 15�nm thick layer of very pure gold onto the Cu2O films on Mo substrate. The probable optical transitions near the band edge were calculated from the spectral response of the device. The band gap calculated at various temperatures show a linear dependence on temperature and the absolute zero value of the band gap is deduced as 2.206�eV. The 2.493�eV direct transition observed in the room temperature shows a temperature dependence. Evidence of phonon assisted indirect transitions were observed at various temperature regions.
    Mathew, X.
    Photocurrent characteristics of a double junction Au/Cu2O/Mo Schottky device 2002 Journal of Materials Science Letters
    Vol. 21(24), pp. 1911-1914 
    article DOI  
    Matsumoto, H., Saito, K., Hasuo, M., Kono, S., and Nagasawa, N.
    Revived interest on yellow-exciton series in Cu2O: An experimental aspect 1996 Solid State Communications
    Vol. 97, pp. 125-129 
    article DOI  
    Abstract: The yellow-exciton series in natural single crystals of Cm0 are studied by one- and two-
    photon spectroscopy in high precision at 2K. The energies of the p-exciton series are
    resolved up to 12p state in one-photon absorption spectra, while those of the (s-d)
    excitons are resolved up to 7(s-d) states in two-photon spectra. The band gap energy is
    evaluated to be 2.1722eV. The different effective Rydberg constants are obtained to be
    0.0981* O.OOOSeV for p-series, 0.1083 t- 0.0138eV and 0.1066 pm 0.0014eV for (s-d)
    series, respectively.
    Review: Natural crystal, T=2 K.
    Excitons, yellow series with s, p and d states
    by absorption of one and two photons.
    Rydberg of all three series.
    Matsumura, H., Fujii, A., and Kitatani, T.
    Properties of High-Mobility Cu2O Films Prepared by Thermal Oxidation of Cu at Low Temperatures 1996 Japanese Journal of Applied Physics
    Vol. 35, pp. 5631-5636 
    article DOI  
    Matsunami, N., Fukuoka, O., Tazawa, M., Kakiuchida, H., and Sataka, M.
    Electronic structure modifications of cuprous-oxide films by ions 2009 Surface and Coatings Technology
    Vol. 203(17-18), pp. 2642-2645 
    article DOI  
    McKinzie, H.L. and O'Keeffe, M.
    High temperature Hall effect in cuprous oxide 1967 Physics Letters A
    Vol. 24(3), pp. 137-139 
    article DOI  
    Abstract: The Hall coefficient has been measured in monocrystalline cuprous oxide from 20�C to 750�C. It is positive below 450�C and negative at higher temperatures.
    Mencer, D.E., Hossain, M.A., Schennach, R., Grady, T., Mc Whinney, H., Gomes, J.A.G., Kesmez, M., Parga, J.R., Barr, T.L., and Cocke, D.L.
    On the surface analysis of copper oxides: the difficulty in detecting Cu$_3$O2 2004 Vacuum
    Vol. 77, pp. 27-35 
    article DOI  
    Merle, J., C., Certier, M., and Nikitine, S.
    Étude du profil de la raie excitonique $n = 1$ de la série jaune de la cuprite en fonction de la température 1967 Journal de Physique Colloques
    Vol. 28(C3), pp. C3-92-C3-94 
    article DOI  
    Abstract: The n = 1 line of the yellow series of cuprous oxide (Cu2O) was studied between 4.2 °K and 112 °K. The results obtained, combined with previous results, show a strong participation of the optical phonons in the scattering of the exciton by phonons. Morever, at very low temperature, the n = 1 line is very sensitive to crystal imperfections.
    Merle, J., C., Nikitine, S., and Schwab, C.
    Étude du profil d'absorption de la raie quadrupolaire excitonique $1S$ de la série jaune de Cu2O en fonction de certains défauts cristallins et de la température 1974 Journal de Physique Colloques
    Vol. 35(C3), pp. C3-27-C3-32 
    article DOI  
    Abstract: High resolution measurements of the 1S yellow exciton quadrupole absorption line of Cu2O have been undertaken in order to study the effects of some physico-chemical parameters (dislocations, impurities and temperature). Below 20 K, an important scattering of the residual line width is observed. A predominant effect of isoelectronic silver is pointed out in this phenomenon : the line broadening is porportional to the silver content up to 400 ppm. In spite of their similar concentrations, an analoguous correlation could not be established for other major trace impurities as Si, Ca and Mg ; nor was it the case for the dislocations. A phenomenological analysis shows that the line shape is given by a Voigt profile, obtained by convolution of a Lorentzian function of width B by a Gaussian function of width A. The variation of B as a function of temperature appears to be independent of the sample, whereas A accounts for the low temperature scattering of the line width. The former results suggest to ascribe the variation of B to an intrinsic effect of phonons and that of A to impurities. This separation is also justified on the basis of a model, developed by Haken. Supporting the previous hypothesis, the thermal variation of B is in quantitative agreement with Toyozawa's theory. The variation of A may be described by the sum of a constant term and an increasing function of temperature. The constant term is directly connected with the Silver content whereas the function describes the effect of a gradual activation of defect centres.
    Miley, H.A.
    Copper Oxide Films 1937 Journal of the American Chemical Society
    Vol. 59(12), pp. 2626-2629 
    article DOI  
    Milne, R.H. and Howie, A.
    Electron microscopy of copper oxidation 1984 Philosophical Magazine A
    Vol. 49(5), pp. 665-682 
    article DOI  
    Abstract: Single-crystal copper specimens of various orientations have been cleaned, oxidized and examined by reflection high-energy electron diffraction in a XJHV chamber and then transferred, under vacuum, to a transmission electron microscope where the shape and orientation of the individual oxide islands could be examined. On all surfaces the islands had a regular appearance with three or four interfaces, the oxide interfacial planes were always &lcub;110&rcub; and fitted close to either &lcub;110&rcub; or &lcub;114&rcub; copper planes. Allowing for tilts of a few degrees, the same epitaxy was observed on all copper faces, the amount of tilt depending on the original surface orientation. Surface steps were shown to be a very important factor in the initial nucleation, influencing the adsorption of oxygen, the siting of the nuclei and the oxide orientation.
    Mimura, K., Lim, J.-W., Isshiki, M., Zhu, Y., and Jiang, Q.
    Brief review of oxidation kinetics of copper at $350^rcC$ to $1050^rcC$ 2006 Metallurgical and Materials Transactions A
    Vol. 37(4), pp. 1231-1237 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;Copper’s oxication mechanism and purity effects were elucidated by oxidizing 99.99 pct (4N), 99.9999 pct (6N), and floating zone refined (&gt;99.9999 pct) specimens in 0.1 MPa oxygen at 350 �C to 1050 �C. Throughout the temperature range, the oxidation kinetics for all specimens obeys the parabolic oxidation rate law. The Cu2O scale grows predominantly, and the rate-determining step is concluded to be outward diffusion of copper atoms in Cu2O. The activation energy at high temperatures, where the lattice diffusion predominates, is 173 kJ/mol, but it becomes lower at intermediate temperatures and even lower at low temperatures because of the contribution of the grain boundary diffusion. At high temperatures, oxidation kinetics is almost uninfluenced by purity, but the lattice-diffusion temperature range is wider for higher-purity copper. At intermediate temperatures, copper oxidation is enhanced because trace impurities can impede growth of Cu2O grains to facilitate grain boundary diffusion. At low temperatures, grain boundary diffusion is possibly hindered by impurities segregated at grain boundaries.
    Minami, T., Tanaka, H., Shimakawa, T., Miyata, T., and Sato, H.
    High-Efficiency Oxide Heterojunction Solar Cells Using Cu2O Sheets 2004 Japanese Journal of Applied Physics
    Vol. 43, pp. L917-L919 
    article DOI  
    Abstract: An inexpensive oxide heterojunction solar cell, consisting of a transparent conducting ZnO thin film deposited on a Cu2O sheet prepared by oxidizing copper at a high temperature, has been demonstrated. High-energy conversion efficiencies over 1% were obtained in Al-doped ZnO (AZO)/Cu2O devices fabricated using AZO thin films prepared by pulsed laser deposition (PLD) or r.f. magnetron sputtering. An open-circuit voltage of 0.41 V, a short-circuit current density of 7.13 mA/cm2, a fill factor of 0.42 and an energy conversion efficiency of 1.21% were obtained in a PLD-AZO/Cu2O device under AM2 solar illumination. The high efficiency of AZO/Cu2O devices is attributed to Cu2O sheets with excellent crystallinity and the low damage resulting from AZO depositions at low temperature.
    Minami, T., Miyata, T., Ihara, K., Minamino, Y., and Tsukada, S.
    Effect of ZnO film deposition methods on the photovoltaic properties of ZnO--Cu2O heterojunction devices 2006 Thin Solid Films
    Vol. 494, pp. 47-52 
    article DOI  

    Cuprite --- Mindat Directory 2010   misc URL 
    Mittal, R., Chaplot, S.L., Mishra, S.K., and Bose, P.P.
    Inelastic neutron scattering and lattice dynamical calculation of negative thermal expansion compounds Cu2O and Ag2O 2007 Physical Review B
    Vol. 75(17), pp. 174303 
    article DOI  
    Abstract: Negative thermal expansion (NTE) is known in Cu2O below 300K and in Ag2O up to its decomposition temperature of about 500K . Inelastic neutron scattering measurements in Cu2O and lattice dynamics calculations of NTE in both Cu2O and Ag2O are reported. The phonon density of states from a polycrystalline sample of Cu2O is measured using the triple-axis spectrometer at Trombay. A lattice dynamical model is used for the calculations of phonon frequencies and their pressure dependence in the entire Brillouin zone. The experimental phonon spectrum is in fair agreement with calculations. The calculated Grüneisen parameters for Cu2O have lower negative values in comparison with Ag2O . This results in a smaller value of negative thermal expansion coefficient in Cu2O , in fair agreement with the experimental data from the literature. An important librational mode is identified that is related to NTE. Variance of bond lengths (⟨ubond2⟩) and their temperature dependence have been calculated and compared with extended x-ray absorption fine structure data that illustrates the nature of the M-O and M-M (M=Cu,Ag) bonds in these compounds.
    Mittiga, A., Salza, E., Sarto, F., Tucci, M., and Vasanthi, R.
    Heterojunction solar cell with 2% efficiency based on a Cu2O substrate 2006 Applied Physics Letters
    Vol. 88, pp. 163502 
    article DOI  
    Mittiga, A., Salza, E., and Sarto, F.
    Characterization of Cu2O Based Heterojunction Solar Cells 2006 Proceedings of 21st European Photovoltaic Solar Energy Conference, Dresden, Germany, pp. 219  inproceedings  
    Mittiga, A., Biccari, F., and Malerba, C.
    Intrinsic defects and metastability effects in Cu2O 2009 Thin Solid Films
    Vol. 517, pp. 2469-2472 
    article DOI  
    Miyata, T., Tanaka, H., Sato, H., and Minami, T.
    P-type semiconducting Cu2O--NiO thin films prepared by magnetron sputtering 2006 Journal of Material Science
    Vol. 41, pp. 5531-5537 
    article DOI  
    Miyata, T., Minami, T., Tanaka, H., and Sato, H.
    Effect of a buffer layer on the photovoltaic properties of AZO/Cu2O solar cells 2006 Proceedings of the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series
    Vol. 6037, pp. 287-296 
    inproceedings DOI  
    Abstract: The effect of a buffer layer and/or interface region on the photovoltaic properties of Al-doped ZnO (AZO)/Cu2O heterojunction solar cells was investigated. The I-V characteristics and photovoltaic properties in AZO/ZnO-In2O3/Cu2O devices were considerably improved by increasing the Zn content (Zn/(In+Zn atomic ratio)) of the ZnO-In2O3 thin-film buffer layer. In addition, the photovoltaic properties of AZO/Zn1-XMgXO/Cu2O devices were found to degrade significantly as the composition (X) was increased above approximately 0.1 because of the increase in resistivity of the buffer layer. Although the spectral response of photocurrent observed in AZO/Zn1-XMgXO/Cu2O devices was considerably affected by altering the value of X, the photo-generated hole in the buffer layer of these devices was not successfully injected into the Cu2O. AZO/Cu2O heterojunctions fabricated using Cu2O sheets with a sulfurized surface exhibited ohmic I-V characteristics.
    Mizuno, K., Izaki, M., Murase, K., Shinagawa, T., Chigane, M., Inaba, M., Tasaka, A., and Awakura, Y.
    Structural and Electrical Characterizations of Electrodeposited p-Type Semiconductor Cu2O Films 2005 Journal of the Electrochemical Society
    Vol. 152(4), pp. C179-C182 
    article DOI  
    Moore, W.J. and Selikson, B.
    The Diffusion of Copper in Cuprous Oxide 1951 The Journal of Chemical Physics
    Vol. 19, pp. 1539-1543 
    article DOI  
    Abstract: Cuprous oxide strips were prepared by the oxidation of copper at 1000°C. The diffusion of radiocopper in this material at 800 to 1050° gave a self-diffusion coefficient, D=0.0436 exp(−36100/RT). Virtually the same D is obtained from experiments in which radiocopper is plated on copper strips, and the distribution of activity measured in the cuprous oxide film formed on oxidation in air. The observed D values are in accord with a predicted relation k/D=4, where k is the parabolic rate constant for copper oxidation. It is suggested that parabolic rate constants with large negative entropies of activation and low heats of activation may be due to grain boundary diffusion.
    Moore, W.J. and Selikson, B.
    Erratum: ``The Diffusion of Copper in Cuprous Oxide'' 1952 The Journal of Chemical Physics
    Vol. 20, pp. 927 
    article DOI  
    Moore, W.J., Ebisuzaki, Y., and Sluss, J.A.
    Exchange and Diffusion of Oxygen in Crystalline Cuprous Oxide 1958 The Journal of Physical Chemistry
    Vol. 62, pp. 1438-1441 
    article DOI  
    Mori, A., Naka, N., and Nagasawa, N.
    Effects of Rayleigh scattering on photovoltaic spectra associated with $1s$ orthoexcitons in Cu2O 2001 Physical Review B
    Vol. 63, pp. 033202 
    article DOI  
    Mori, A., Naka, N., and Nagasawa, N.
    Erratum: Effects of Rayleigh scattering on photovoltaic spectra associated with $1s$ orthoexcitons in Cu2O 2001 Physical Review B
    Vol. 63, pp. 169901(E) 
    article DOI  
    Mrowec, S.
    On the mechanism of high temperature oxidation of metals and alloys 1967 Corrosion Science
    Vol. 7(9), pp. 563-578 
    article DOI  
    Abstract: On the basis of the author and co-workers' studies and results of investigations of other authors, the mechanism governing formation of the mono-phase, multi-layer scales on pure metals has been discussed. It has been shown that mechanism of oxidation and the morphological structure of the scales depend in the first place on the geometrical parameters of the metal-scale system and also on the presence in the metallic phase of contaminants which are insoluble in the products of oxidation. It is concluded that the mechanism of formation of the hetero-phase, double-layer scales on binary alloys constitutes a particular case of the oxidation of pure metals.
    Mrowec, S. and Stokłosa, A.
    Oxidation of Copper at High Temperatures 1971 Oxidation of Metals
    Vol. 3, pp. 291-311 
    article DOI  
    Abstract: The kinetics and mechanism of copper oxidation have been measured over the temperature range 900–1050°C and the pressure range 5×10–3 to 8×10–1 atm. It has been shown that, at the pressures lower than the dissociation pressure of CuO, the oxide scale formed on flat fragments of the copper specimens is compact and composed of a single layer, adhering closely to the metallic base. Growth of the scale proceeds under these conditions by outward diffusion of metal. The rate of the process under the conditions for which single-phase scales are formed increases with increasing oxygen pressure according to the equation:

    Kp = const p O2 $^1/3.9$
    the activation energy for oxidation is 24 ± 2 kcal/mole. On the basis of theFueki-Wagner method and the method proposed in the present work, the self-diffusioncoefficients of copper in cuprous oxide were calculated as a functionof oxygen pressure and temperature. It has been shown that distribution of thedefect concentration in the growing layer of the scale is linear.

    Mrowec, S., Stokłosa, A., and Godlewski, K.
    Thermodynamics and Kinetics of Point Defects in Cuprous Oxide 1974 Crystal Lattice Defects (ISSN: 0732-8699)
    Vol. 5, pp. 239-255 
    Mrowec, S.
    Defects and diffusion in solids, an introduction 1980   book  
    Mrowec, S.
    On the defect structure and diffusion kinetics in transition metal sulphides and oxides 1988 Reactivity of Solids
    Vol. 5(4), pp. 241-268 
    article DOI  
    Abstract: Defect and transport properties of transition metal sulphides are discussed showing similarities and differences between them and the oxide systems. Metal sulphides show the same type of predominant defects as metal oxides, the concentration of defects in the majority of sulphides being much higher than in the corresponding oxides. Defect mobility in sulphides is generally higher than in the corresponding oxides but these differences do not exceed one order of magnitude. Thus, much higher diffusivities in the majority of sulphides are due mainly to the higher concentration of defects.
    Mukhopadhyay, A., Chakraborty, A., Chatterjee, A., and Lahiri, S.
    Galvanostatic deposition and electrical characterization of cuprous oxide thin films 1992 Thin Solid Films
    Vol. 209(1), pp. 92-96 
    article DOI  
    Abstract: Semiconducting cuprous oxide (Cu2O) thin films, important for low cost solar cell and oxygen or humidity sensor applications, were galvanostatically deposited at 40-60 �C on copper substrates. The deposition kinetics, studied up to a film thickness of about 20 [mu]m, was found to be linear and independent of deposition temperature. The observed film growth rate was in excellent agreement with the growth rates predicted from Faraday's law of electrolysis. The deposited films exhibited a preferred (200) orientation. The current-voltage characteristics of the electrodeposited Cu2O/Cu diodes exhibited a metal-insulator-semiconductor type of behaviour, suggesting the presence of a thin interfacial insulating layer between Cu2O and copper. The electrical conductivity of Cu2O films was found to vary exponentially with temperature in the 145-300�C range with an associated activation energy of 0.79 eV.
    Musa, A.O., Akomolafe, T., and Carter, M.J.
    Production of cuprous oxide, a solar cell material, by thermal oxidation and a study of its physical and electrical properties 1998 Solar Energy Materials and Solar Cells
    Vol. 51, pp. 305-316 
    article DOI  
    Mysyrowicz, A., Hulin, D., and Antonetti, A.
    Long Exciton Lifetime in Cu2O 1979 Physical Review Letters
    Vol. 43, pp. 1123-1126 
    article DOI  
    Abstract: A lifetime of 13 textmu s is measured for the paraexciton in Cu2O at 10 K. The orthoexciton lifetime is shown to be limited by ortho-para transfer rate. A high density of paraexcitons is generated, leading to deviations from classical statistics.
    Mysyrowicz, A., Hulin, D., and Antonetti, A.
    Erratum: Long exciton lifetime in Cu2O 1979 Physical Review Letters
    Vol. 43, pp. 1275 
    article DOI  
    Mysyrowicz, A.
    EXCITONS AS A NEW QUANTUM SYSTEM 1980 Journal de Physique Colloques
    Vol. 41, pp. C7-281-C7-294 
    article DOI  
    Abstract: In a first part, a brief review of some excitonic properties is presented, with the accent put on their relevance with respect to the possibility of Bose-Einstein condensation. In a second part, recent experimental evidence is described, which supports the idea that excitonic particles may form a highly quantum fluid. In Cu20, the analysis of the exciton decay spectrum shows a gradual evolution of the gas from a classical regime at low densities up to a strongly degenerate one at high densities, with a chemical potential µ ~ 0. In CuCl excitons are unstable against formation of molecules (biexcitons). It is possible to generate directly a high density gas of biexcitons with momentum K ~ 0 by giant two-photon absorption. At low excitation, the observed molecular emission is in agreement with Maxwell -Boltzmann statistics. At high densities, strong deviations occur. In particular, the appearance of a sharp emission line is attributed to the presence of a Bose-Einstein condensate of excitonic molecules.
    Mysyrowicz, A., Trauernicht, D.P., Wolfe, J.P., and Trebin, H.R.
    Stress dependence of the paraexciton in Cu2O 1983 Physical Review B
    Vol. 27(4), pp. 2562-2564 
    article DOI  
    Mysyrowicz, A. and Fortin, E.
    Superfluidité excitonique dans Cu2O 1993 Canadian Journal of Physics
    Vol. 71(3-4), pp. 165-167 
    article URL 
    Mysyrowicz, A., Benson, E., and Fortin, E.
    Directed Beam of Excitons Produced by Stimulated Scattering 1996 Physical Review Letters
    Vol. 77(5), pp. 896-899 
    article DOI  
    Mysyrowicz, A., Leblanc, P.J., and Fortin, E.
    Comment on ``Some considerations concerning the detection of excitons by field ionization in a Schottky barrier'' 2003 Physica Status Solidi (b)
    Vol. 239, pp. 257-260 
    article DOI  
    Nadesalingam, M.P., Mukherjee, S., Somasundaram, S., Chenthamarakshan, C.R., de Tacconi, N.R., Rajeshwar, K., and Weiss, A.H.
    Effect of Vacuum Annealing on the Surface Chemistry of Electrodeposited Copper(I) Oxide Layers as Probed by Positron Annihilation Induced Auger Electron Spectroscopy 2007 Langmuir
    Vol. 23(4), pp. 1830-1834 
    article DOI  
    Abstract: Vacuum anneal induced changes in the surface layers of electrodeposited copper(I) oxide (Cu2O) were probed by time-of-flight positron annihilation induced Auger electron spectroscopy (TOF-PAES) and by electron induced Auger electron spectroscopy (EAES). Large changes in the intensity of the Cu PAES intensity resulting from isochronal in situ vacuum anneals made at increasing temperatures indicated that, before thermal treatment, the surface was completely covered by a carbonaceous overlayer and that this layer was removed, starting at a temperature between 100 and 200 °C, to expose an increasing amount of Cu in the top layer as the anneal temperature was increased. The thickness of this overlayer was estimated to be ∼4 Å based on analysis of the EAES data, and its variation with the thermal anneal temperature was mapped. This study demonstrated the order-of-magnitude enhancement in the sensitivity of PAES to the topmost surface layer in Cu2O relative to the EAES counterpart; factors underlying this contrast are discussed. Finally, the implications of ultrathin carbon layers on semiconductor surfaces are discussed.
    Nair, M.T.S., Guerrero, L., Arenas, O.L., and Nair, P.K.
    Chemically deposited copper oxide thin films: structural, optical and electrical characteristics 1999 Applied Surface Science
    Vol. 150(1-4), pp. 143-151 
    article DOI  
    Abstract: Thin films of copper oxide with thickness ranging from 0.05-0.45 [mu]m were deposited on microscope glass slides by successively dipping them for 20 s each in a solution of 1 M NaOH and then in a solution of copper complex. Temperature of the NaOH solution was varied from 50-90�C, while that of the copper solution was maintained at room temperature. X-ray diffraction patterns showed that the films, as prepared, are of cuprite structure with composition Cu2O. Annealing the films in air at 350�C converts these films to CuO. This conversion is accompanied by a shift in the optical band gap from 2.1 eV (direct) to 1.75 eV (direct). The films show p-type conductivity, ~5�10-4 [Omega]-1 cm-1 for a film of thickness 0.15 [mu]m. Electrical conductivity of this film increases by a factor of 3 when illuminated with 1 kW m-2 tungsten halogen radiation. Annealing in a nitrogen atmosphere at temperatures up to 400�C does not change the composition of the films. However, the conductivity in the dark as well as the photoconductivity of the film increases by an order of magnitude. The electrical conductivity of the CuO thin films produced by air annealing at 400�C, is high, 7�10-3 [Omega]-1 cm-1. These films are also photoconductive.
    Naka, N., Hasuo, M., and Nagasawa, N.
    Two-photon photo-voltaic spectroscopy on wannier excitons in Cu2O 1998 Physics of the Solid State
    Vol. 40, pp. 847-849 
    article DOI  
    Naka, N., Hashimoto, S., and Ishihara, T.
    Thin Films of Single-Crystal Cuprous Oxide Grown from the Melt 2005 Japanese Journal of Applied Physics
    Vol. 44, pp. 5096-5101 
    article DOI  
    Abstract: We have grown thin films of cuprous oxide (Cu2O) from the melt in a small gap between paired substrates of MgO or Al2O3 single crystals. The films are characterized by scanning electron microscopy, X-ray diffraction and optical spectroscopy. The thickness of the films is found to range from 16 nm to 20 μm. The domain structure with dimensions of 0.1--1 mm is found and attributed to single crystals oriented into different directions. The narrow peaks in rocking curves and in azimuthal angle rotations indicate the formation of highly oriented single-crystal films. Clear peaks due to yellow, green, blue, and violet excitons are observed in optical spectra. The positions of the peaks depend on the thickness of the film, implying strain-induced shifts of the exciton levels.
    Nakamura, Y., Naka, N., and Nagasawa, N.
    Effects of wandering photons on the excitonic optical signals in Cu2O crystals 2001 Physical Review B
    Vol. 64(7), pp. 075203 
    article DOI  
    Abstract: A Monte Carlo simulation is performed to estimate the intensity distribution and the effective path length of the scattering light in Cu2O single crystals, assuming elastic isotropic scattering. The effect of internal reflections is also taken into account. The mean-free path of the relevant photons in the samples is estimated to be 1.4+/-0.4 mm. The resultant path length of the scattering photons becomes longer than the rectilinear length. This results in apparent three times larger absorption coefficient in off-axis geometry. This is found to be independent of the temperature in the range between 30 and 180 K, and of the photon energy in the region of the phonon-assisted exciton absorption edge associated with Γ-3 phonons. The results of the simulation well reproduce the shape of absorbance, electroluminescence, and photovoltaic spectra.
    Nakano, T., Ohtani, K., Kinoshita, A., and Okuda, T.
    Growth of Cuprous Oxide (Cu2O) Crystal 1964 Japanese Journal of Applied Physics
    Vol. 3(2), pp. 124 
    article DOI  
    Nakano, Y., Saeki, S., and Morikawa, T.
    Optical bandgap widening of $p$-type Cu2O films by nitrogen doping 2009 Applied Physics Letters
    Vol. 94, pp. 022111 
    article DOI  
    Nakaoka, K., Ueyama, J., and Ogura, K.
    Photoelectrochemical Behavior of Electrodeposited CuO and Cu2O Thin Films on Conducting Substrates 2004 Journal of the Electrochemical Society
    Vol. 151(10), pp. C661-C665 
    article DOI  
    Nemoto, T. and Nakano, T.
    The Effect of Silicon in Cuprous Oxide 1967 Japanese Journal of Applied Physics
    Vol. 6, pp. 543-544 
    article DOI  
    Neogi, P.
    Interfacial stability of electrodeposition of cuprous oxide films 2004 Journal of Chemical Physics
    Vol. 121, pp. 9630-9638 
    article DOI  
    Abstract: Experiments on deposition of Cu2O films from basic cupper sulfate solution show that copper also deposits. At low, but basic values of pH only copper deposits and at high pH only cuprous oxide deposits. In the intermediate range where both compete the system shows oscillations at ``constant current.'' Linear stability analysis has been conducted for such an electrochemical cell to show that oscillations can take place in the parameter space identified in the experiments. The results are keeping with most of the experimental observations, which are many, but not with all. The physical mechanisms behind the oscillations are explained in terms of competing reactions.
    Neskovska, R., Ristova, M., Velevska, J., and Ristov, M.
    Electrochromism of the electroless deposited cuprous oxide films 2007 Thin Solid Films
    Vol. 515(11), pp. 4717-4721 
    article DOI  
    Abstract: Thin cuprous oxide films were prepared by a low cost, chemical deposition (electroless) method onto glass substrates pre-coated with fluorine doped tin oxide. The X-ray diffraction pattern confirmed the Cu2O composition of the films. Visible transmittance spectra of the cuprous oxide films were studied for the as-prepared, colored and bleached films. The cyclic voltammetry study showed that those films exhibited cathode coloring electrochromism, i.e. the films showed change of color from yellowish to black upon application of an electric field. The transmittance across the films for laser light of 670 nm was found to change due to the voltage change for about 50%. The coloration memory of those films was also studied during 6 h, ex-situ. The coloration efficiency at 670 nm was calculated to be 37 cm2/C.
    Nevskaya, E.Y., Gorichev, I.G., Safronov, S.B., Zaitsev, B.E., Kutepov, A.M., and Izotov, A.D.
    Interaction between Copper(II) Oxide and Aqueous Ammonia in the Presence of Ethylenediaminetetraacetic Acid 2001 Theoretical Foundations of Chemical Engineering
    Vol. 35(5), pp. 503-509 
    article DOI  
    Abstract: The interaction of copper(II) oxide with aqueous ammonia containing ethylenediaminetetraacetic acid (H4L) is analyzed in terms of formal heterogeneous kinetics and the fractal dimension of the dissolving space. It is shown experimentally that, in the presence of H4L, the dissolution rate of CuO grows with increasing ammonia concentration. At a fixed ammonia concentration, the dissolution rate of CuO passes through a maximum at an H4L concentration of 8 × 10–3mol/l. Two mechanisms of dissolution are suggested, namely, an adsorption and a redox mechanism. The adsorption mechanism involves four intermediate species and implies that the dissolution rate is a fractional rational function of the EDTA concentration. The redox mechanism takes into account the oxide/electrolyte interfacial potential. The role of the CuOHL3–ion is elucidated, and the kinetic parameters of dissolution are derived.
    Nie, X., Wei, S.-H., and Zhang, S.B.
    First-principles study of transparent p-type conductive SrCu2O2 and related compounds 2002 Physical Review B
    Vol. 65, pp. 075111 
    article DOI  
    Nikitine, S., Perny, G., and Sieskind, M.
    Sur les séries de raies d'absorption de lames de Cu2O aux basses températures 1954 Comptes Rendus
    Vol. 238, pp. 67-69 
    article URL 
    Nikitine, S., Couture, L., Sieskind, M., and Perny, G.
    Étude des raies d'absorption de lames de Cu2O et de HgI2 aux trés basses températures 1954 Comptes Rendus
    Vol. 238, pp. 1786-1788 
    article URL 
    Nikitine, S., Sieskind, M., and Perny, G.
    Déplacement du spectre d'absorption de l'oxyde cuivreux en fonction de la température 1954 Comptes Rendus
    Vol. 238, pp. 1987-1989 
    article URL 
    Nikitine, S.
    Étude des spectres de l'exciton aux trés basses températures 1956 Journal de Physique et Le Radium
    Vol. 17(8-9), pp. 817-819 
    article DOI  
    Abstract: An account is given on the résults obtained in the author's laboratory on the absorption spectra of a number of crystals at very low temperatures. In most cases it has been found that the absorption spectra give evidence of narrow line structure. The breadth of some of these lines does not exceed one Å or even less. Sometimes they form hydrogen like series which are in several compourids accompanied by vibration satellites. In anisotropic crystals the absorption lines are dichroic. These results are believed to give an experimental evidence for the existence of excitons.
    Nikitine, S.
    Spectroscopie du corps solide et spectres d'excitons 1959 Journal of Physics and Chemistry of Solids
    Vol. 8, pp. 190-195 
    article DOI  
    Abstract: Not Available
    Nikitine, S.
    Experimental investigations of exciton spectra in ionic crystals 1959 Philosophical Magazine
    Vol. 4(37), pp. 1-31 
    article DOI  
    Nikitine, S., Grun, J.B., and Sieskind, M.
    Etude Spectrophotometrique De La Serie Jaune De Cu2O Aux Basses Temperatures 1961 Journal of Physics and Chemistry of Solids
    Vol. 17, pp. 292-300 
    article DOI  
    Nikitine, S., Grun, J.B., Certier, M., Deiss, J.L., and Grossman, M.
    1962 Proceedings of the International Conference on the Physics of Semiconductors, Exeter, pp. 409  inproceedings  
    Nikitine, S. and Grosmann, M.
    Effet de défauts causés par un bombardement de neutrons sur le spectre excitonique de Cu2O 1963 Journal de Physique
    Vol. 24(7), pp. 525-531 
    article DOI  
    Abstract: Samples of cuprous oxide have been irradiated with fast neutrons. The modifications of the exciton spectrum observed are similar to those produced by an electric field applied to the crystal. The irradiation probably produces charged defects which produce an internal electric field. The evaluation of this field allows an evaluation of the concentration of defects produced by the irradiation.
    Nikitine, S., Zielinger, J.P., Coret, A., and Zouaghi, M.
    Evaluation des parametres des photoporteurs dans la cuprite a $79^rcK$ 1965 Physics Letters
    Vol. 18(2), pp. 105-106 
    article DOI  
    Nikitine, S., Coret, A., Zielinger, J.P., Jeanclaude, C., Boehm, C., and Zouaghi, M.
    The Relationship between Exciton Absorption and the Photoelectric Effect 1965 The Journal of Physical Chemistry
    Vol. 69(3), pp. 745-751 
    article DOI  
    Nikitine, S., Coret, A., Zielinger, J.P., Jeanclaude, C., and Boehm, C.
    Spectres d'absorption et de photoconductivité de cristaux semi-conducteurs et isolants 1965 Journal de Physique
    Vol. 26(3), pp. 132-134 
    article DOI  
    Abstract: We have compared the absorption and photoconductivity spectra of cuprite samples at 4.2 oK. All the absorption edges and exciton lines appear in the photoconductivity spectrum as maxima or as minima. We have also studied, for the same sample, the photomagnetoelectrical effect. The photoconductivity spectra of others crystals were investigated : HgI2, PbI2, GaSe, CuCl. The same phenomena are observed.
    Nikitine, S., Deiss, J.L., Certier, M., Merle, J.C., and Daunois, A.
    Sur Les Effets D'un Champ électrique Et De Champs électrique Et Magnétique Croisés Sur La Raie Quadrupolaire $1s$ De La Série Jaune De Cu2O 1966 Journal de Physique Colloques
    Vol. 27, pp. C2-107-C2-110 
    article DOI  
    Nikitine, S.
    ``Excitons'' in Optical Properties of Solids 1969 , pp. 197  inbook  
    Nikitine, S.
    ``Introduction to exciton spectroscopy'' in Excitons at High Density 1975 Excitons at High Density  inbook DOI  
    Abstract: Without Abstract
    Nikitine, S., Elkomoss, S.G., and Schwab, C.
    Line width and exciton-impurity scattering in Cu2O 1978 Journal of Molecular Structure
    Vol. 45, pp. 377-387 
    article DOI  
    Abstract: The variation of the line width of the n = 1 line of the yellow series in Cu2O as a function of the concentration N of substitutional Ag+ ions (ref. 1) is interpreted on ground of a theory similar to the Lorentzian collision line broadening theory. It is shown that the line must acquire a Voigt shape when the concentration of Ag+ increases. This Voigt shape line is obtained from the convolution of a Gaussian component of a constant line width [Delta]vG = 0.57 cm-1 (obtained from the experiment by extrapolation to N --> 0) and a Lorentzian component of line width [Delta]vl variable with N. The shape of the experimental (ref. 1) lines for different concentrations N and the theoretical lines calculated is in surprinsingly good agreement. From this comparison a collision cross-section and mean free path of excitons can be calculated. The obtained values are [sigma] [reverse similar, equals] 1014 cm2 and XXX = 3.2 10-5 cm for a concentration N = 1018 cm-3. Further discussion of these results leads to useful information.
    Nix, F.C.
    Photo-conductivity 1932 Review of Modern Physics
    Vol. 4(4), pp. 723-766 
    article DOI  
    Njeh, A., Wieder, T., and Fuess, H.
    Reflectometry studies of the oxidation kinetics of thin copper films 2002 Surface and Interface Analysis
    Vol. 33(7), pp. 626-628 
    article DOI  
    Abstract: Oxide formation on magnetron-sputtered thin copper films (35 nm thickness) was studied by x-ray reflectometry and grazing incidence x-ray diffraction. The films were oxidized in air at temperatures of 175� C, 200� C, 225� C and 250� C. The reflectometry and the diffractometry data indicate the formation of Cu2O. A power-law dependence of the oxide layer thickness was found. The activation energy obtained is weakly time dependent. Copyright � 2002 John Wiley & Sons, Ltd.
    Noguet, C., Schwab, C., Sennett, C., Sieskind, M., and Viel, C.
    Contribution à l'étude de la constante diélectrique de la cuprite. I. Détermination de la constante diélectrique par des méthodes optiques 1965 Journal de Physique
    Vol. 26(6), pp. 317-320 
    article DOI  
    Abstract: The dielectric constant of cuprous oxide has been measured by an optical method for frequencies varying from 50 cm-1 to 4 000 cm -1. The extrapolated value of e is found to be e stat = 7.5 ± 0:2. The dispersion curve may be represented by a formula of the type [FORMULA] in terms of the two infra-red active frequencies ? 1 and ?2. From this it is possible to deduce the effective charge on the ions, which is 0.34 and - 0.68 électron charge for the copper and oxygen ions respectively. This corresponds to a weakly ionic crystal.
    Noguet, C.
    Contribution à l'étude de la constante diélectrique de la cuprite. II. Détermination de la constante diélectrique statique par des méthodes électriques 1965 Journal de Physique
    Vol. 26(6), pp. 321-322 
    article DOI  
    Noguet, C., Sennett, C., and Sieskind, M.
    Contribution à l'étude de la constante diélectrique de la cuprite. III. Incidences sur les données spectroscopiques de Cu2O. Discussion 1965 Journal de Physique
    Vol. 26(6), pp. 323-324 
    article DOI  
    Noguet, C.
    1969 School: University of Strasbourg  phdthesis  
    Noguet, C.
    Propriétés diélectriques de l'oxyde cuivreux aux audiofréquences entre $150^rcK$ et $320^rcK$ 1970 Journal de Physique
    Vol. 31(4), pp. 393-399 
    article DOI  
    Noguet, C., Tapiero, M., and Zielinger, J.P.
    A New Model for Interpreting the Electric Conduction Phenomena in Cu2O Single Crystals 1974 Physica Status Solidi (a)
    Vol. 24, pp. 565-574 
    article DOI  
    Noguet, C., Tapiero, M., Schwab, C., Zielinger, J.P., Trivich, D., Komp, R.J., Wang, E.Y., and Weng, K.
    Cuprous oxide as a photovoltaic converter 1978 Proceedings of the 1st European Photovoltaic Solar Energy Conference, Luxembourg, pp. 1170-1179  inproceedings  
    Noguet, C., Pierrat, D., Tapiero, M., and Zielinger, J.P.
    Longueur de diffusion des porteurs minoritaires et structure de jonction des diodes Cu/Cu2O 1980 Revue de Physique Appliquée
    Vol. 15(3), pp. 595-602 
    article DOI  
    Nolan, M. and Elliott, S.D.
    The p-type conduction mechanism in Cu2O: a first principles study 2006 Physical Chemistry Chemical Physics
    Vol. 8, pp. 5350-5358 
    article DOI  
    Nolan, M. and Elliott, S.D.
    Tuning the Transparency of Cu2O with Substitutional Cation Doping 2008 Chemistry of Materials
    Vol. 20, pp. 5522-5531 
    article DOI  
    Nolan, M.
    Defects in Cu2O, CuAlO2 and SrCu2O2 transparent conducting oxides 2008 Thin Solid Films
    Vol. 516, pp. 8130-8135 
    article DOI  
    Abstract: Not Available
    Nolan, M. and Elliott, S.D.
    Tuning the electronic structure of the transparent conducting oxide Cu2O 2008 Thin Solid Films
    Vol. 516, pp. 1468-1472 
    article DOI  
    O'Hara, K.E., Gullingsrud, J.R., and Wolfe, J.P.
    Auger decay of excitons in Cu2O 1999 Physical Review B
    Vol. 60, pp. 10872-10885 
    article DOI  
    Abstract: The nonradiative recombination of an exciton due to a collision with another exciton (i.e., Auger recombination) is the dominant loss mechanism for excitons at high densities in photoexcited Cu2O. The principal evidence is that (a) the observed lifetime of excitons shortens substantially at high densities, and (b) the exciton density increases sublinearly with increasing excitation power. To achieve exciton densities at which this two-body decay process comes into play, the particles are produced within a few micrometers of the crystal surface using intense pulsed excitation with photon energies well above the semiconductor band gap. In the past, determination of the “Auger constant” A in the two-body decay rate, 1/τ=An, was limited by insufficient knowledge of the exciton density n. In the present work, we have determined the density of excitons by (a) measuring their absolute brightness in a calibrated optical system and (b) measuring the expanding volume occupied by the excitons. The luminescence signal following subnanosecond laser excitation exhibits a decay rate which is strongly dependent on the particle density. While some modeling is required to determine the volumes at earliest times, we believe that we have determined the Auger constant to within a factor of 2. The experimental value, A=7×10-17 cm3/ns, is nearly two orders of magnitude larger than that derived from spectroscopic analysis. Such a strong Auger decay prevents the gas from achieving average densities in the quantum statistical regime of an ideal gas.
    Review: A summary of O'Hara thesis with some more details.

    Diffusion coefficient of excitons (maybe is wrong) see paper.

    O'Hara, K.E., Ó Súilleabháin, L., and Wolfe, J.P.
    Strong nonradiative recombination of excitons in Cu2O and its impact on Bose-Einstein statistics 1999 Physical Review B
    Vol. 60(15), pp. 10565-10568 
    article DOI  
    O'Hara, K.E.
    Relaxation Kinetics of Excitons in Cuprous Oxide 1999 School: University of Illinois at Urbana-Champaign  phdthesis URL 
    O'Keeffe, M. and Moore, W.J.
    Electrical Conductivity of Monocrystalline Cuprous Oxide 1961 The Journal of Chemical Physics
    Vol. 35, pp. 1324-1328 
    article DOI  
    O'Keeffe, M. and Moore, W.J.
    The Magnetic Susceptibility of Cupric Oxide 1962 Journal of Physics and Chemistry of Solids
    Vol. 23, pp. 261-266 
    article DOI  
    O'Keeffe, M. and Stone, F.S.
    The Magnetochemistry and Stoichiometry of the Copper-Oxygen System 1962 Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences
    Vol. 267, pp. 501-517 
    article DOI  
    Abstract: An enclosed magnetic balance has been used to study the changes in magnetic susceptibility which take place during the oxidation of copper and during the treatment of cuprous and cupric oxides in oxygen and in vacuo. Cuprous oxide prepared by high temperature oxidation and cooled in vacuo from 1060 $^rc$C has a gram susceptibility of -0.155 x 10$^-6$, independent of temperature in the range 14 to 293 $^rc$K. Cuprous oxide quenched from 1045 $^rc$C in air has a gram susceptibility which varies with temperature from $i_g$ = -0.150 x 10$^-6$ at 293 $^rc$K to $i_g$ = -0.127 x 10$^-6$ at 14 $^rc$K. The paramagnetic component of the susceptibility of the latter oxide is attributed to magnetic centres (cation vacancies and positive holes) arising from the oxygen excess, and its absolute value is compared with that expected from different models for the disorder. It is suggested that single vacancies aggregate on cooling. Cuprous oxide prepared by oxidation at low temperatures (120 to 160 $^rc$C) and low oxygen pressures may be rendered much more paramagnetic than the oxide prepared at high temperatures. A survey of the magnetic properties has been made by carrying out such oxidations in situ on the magnetic balance. It is concluded that beyond the stoichiometric point on the oxygen excess side an extensive metastable non-stoichiometry may be sustained at these temperatures. Further oxidation or, alternatively, a treatment in vacuo at a high temperature causes the oxygen excess to be nucleated and antiferromagnetic cupric oxide is formed. Similar studies with copper supported on silica show that the metastable paramagnetism is associated more especially with the surface. Attention is given to the fact that cupric oxide may be rendered paramagnetic under certain circumstances, but a distinction is drawn between this effect and the paramagnetism of non-stoichiometric cuprous oxide. The significance of the results for the mechanism of the oxidation of copper is discussed. It is suggested that CuO nucleates internally in Cu$_2$O, and a close analogy then exists between the oxidation of copper to Cu$_2$O and the oxidation of Cu$_2$O to CuO. The surface reaction, namely, incorporation of oxygen into cuprous oxide, is the same in both cases. A mechanism is put forward to account for the relative ease of cation vacancy production (and hence non-stoichiometry) in the surface layers during this process.
    O'Keeffe, M. and Moore, W.J.
    Thermodynamics of the Formation and Migration of Defects in Cuprous Oxide 1962 The Journal of Chemical Physics
    Vol. 36, pp. 3009-3013 
    article DOI  
    Abstract: The number of gram atoms of excess oxygen y per mole of cuprous oxide has been measured by means of a quartz-fiber microbalance. The combined pressure and temperature dependence is log10 y=0.27 log10PO2—(21.7 kcal) / RT+0.29 with T in °K and PO2 in mm Hg. This relation has been utilized to determine the extent of the cuprite field in the copper-oxygen system. The cation vacancy V+ is formed in Cu2O by the reaction ¼O2½O=+V. The entropy of formation of the vacancy, computed from S=S(O=)+S(V+)−S(O2) is S(V+) = 12.1 cal deg—1. This positive entropy, caused by the lowering of the vibration frequencies of neighboring copper atoms, is the principal factor responsible for the defect structure of cuprous oxide. The new thermodynamic data lead to a quantitative determination of the diffusion parameters for copper in Cu2O.
    O'Keeffe, M., Ebisuzaki, Y., and Moore, W.J.
    The Defect Structure of Cuprous Oxide 1963 Journal of the Physical Society of Japan
    Vol. 18, {S}uppl. {II}, pp. 131-136 
    O'Keeffe, M.
    Infrared Optical Properties of Cuprous Oxide 1963 The Journal of Chemical Physics
    Vol. 39, pp. 1789-1793 
    article DOI  
    O'Keeffe, M.
    Semi conducting properties of cuprous oxide and related research 1967   techreport URL 
    Abstract: The report summarizes the research on semiconducting properties of cuprous oxide performed under this grant. Contributions have been made to the understanding of the behavior of cuprous oxide at high temperatures with special reference to the electrical properties and defect structure. Interdiffusion studies by thermogravimetric means have been made on wustite and manganous oxide. Further work is being continued under another grant.. Presented at the International Symposium on Kinetics of Ionic Reactions, Alfred, N. Y.
    O'Reilly, M., Jiang, X., Beechinor, J.T., Lynch, S., Ní Dheasuna, C., Patterson, J.C., and Crean, G.M.
    Investigation of the oxidation behaviour of thin film and bulk copper 1995 Applied Surface ScienceProceedings of the First European Workshop on Materials for Advanced Metallization
    Vol. 91(1-4), pp. 152-156 
    article DOI  
    Abstract: Thermogravimetry (TGA) and spectroscopic ellipsometry (SE) were employed to examine the oxidation behaviour of Cu. Thermogravimetry was used to study the oxidation behaviour of bulk Cu (99.9% purity) in the range 250 to 500�C. Within this temperature range the predominant oxidation product was cupric oxide (CuO) and the reaction followed a cubic rate law. The activation energy was calculated to be 71 kJ/mol. At lower temperatures (< 150�C) spectroscopic ellipsometry was employed to characterise the oxidation kinetics of as-deposited electroless and sputtered Cu films. Analysis of the experimental spectra indicated that the rate at which the oxide grew followed an inverse logarithmic rate law. The oxidation product, which had the typical ruby red hue of cuprous oxide (Cu2O), was confirmed as the predominant oxidation product with X-ray diffraction (XRD). The oxide scale which formed had very poor adhesion to the base material. Field emission electron microscopy (FEM) was used to examine the oxide scale topography. The low temperature product was seen to be composed of small, tightly packed grains approximately 60 nm in diameter whilst at temperatures above 300�C whisker-like crystals were also present.
    Oba, F., Ernst, F., Yu, Y., Liu, R., Kothari, H.M., and Switzer, J.A.
    Epitaxial Growth of Cuprous Oxide Electrodeposited onto Semiconductor and Metal Substrates 2005 Journal of the American Ceramic Society
    Vol. 88(2), pp. 253-270 
    article DOI  
    Abstract: It is demonstrated that cuprous oxide (Cu2O) can be electrodeposited epitaxially onto silicon (Si) and indium phosphide (InP) (001) single-crystalline substrates from aqueous solution. Epitaxial electrodeposition under these conditions is remarkable considering the strong driving force for the formation of amorphous native oxide layers on Si and InP substrates. To elucidate the growth mechanisms, the microstructure of the interfaces between the Cu2O layer and the two different substrates was investigated by TEM (transmission electron microscopy) in conjunction with XEDS (X-ray energy-dispersive spectroscopy) and EELS (electron energy-loss spectroscopy). In both heteroepitaxial systems, the Cu2O layers have a unique but non-trivial crystallographic orientation relationship (OR) with the substrate, which can be described as a 45� rotation around the common [001] axis representing the substrate normal. We show that this relationship minimizes the overall misfit between corresponding interatomic spacings of the two adjacent crystals. In apparent contradiction to the unique OR, TEM revealed that in both hetero-systems the Cu2O layer is separated from the substrate by an amorphous interlayer. The thickness of the interlayer typically is a few nanometers. The presence of an amorphous interlayer contrasts with our experimental results on electrodeposited Cu2O on Au (001) single-crystal substrates, also included in this article, where TEM shows the Cu2O epilayer in direct contact with the substrate. XEDS and EELS analysis of the chemical composition and bonding at Cu2O/Si and Cu2O/InP interfaces in the as-grown state as well as after tempering revealed that the interlayer is mainly composed of SiO2 and InPO4, respectively. Most likely, the observed epitaxial layers on top of an amorphous interlayer evolve by nucleation of epitaxial Cu2O directly on the substrate. While simultaneous oxidation of the substrate leads to the formation of an amorphous layer, the epitaxial nuclei can laterally overgrow the oxide. Consequently, the local composition of the amorphous layer varies with the nature of the substrate.
    Ochin, P., Petot, C., and Petot-Ervas, G.
    Thermodynamic study of point defects in Cu$_2-delta$O. Electrical conductivity measurements at low oxygen partial pressures 1984 Solid State Ionics
    Vol. 12, pp. 135-143 
    article DOI  
    Abstract: The electrical conductivity of cuprous oxide has been measured in the temperature range 600–1100°C and for oxygen partial pressures between 10−7 atm and the oxidation limit of Cu2−δO. Oxygen partial pressures lower than 10−5 atm hav e been obtained either by the partial vacuum technique, the opening of an adjustable leak being tied to the response of an electrochemical gauge placed near the sample, or under a total pressure of 1 atm, the oxygen partial pressure in argon being lowered by passing through an electrochemical pump. The electrical conductivity values, obtained for oxygen partial pressures lower than 10−5 atm, are in agreement with those measured at higher oxygen partial pressures, using a classical method for obtaining PO2. The results obtained may be explained assuming the existence of interactions among defects leading to the formation of complex associates of the type (V'CuVxCu). At lower PO2, the values of the slope 1/n= (∂lnσ/∂lnPO2)T, lower than 1/8, may be explained by impurity effects or by the prevailing influence of interstitial copper defects.
    Ochin, P., Petot-Ervas, G., and Petot, C.
    Mass Transport in Cuprous Oxide 1985 Journal of Physics and Chemistry of Solids
    Vol. 46, pp. 695-700 
    article DOI  
    Abstract: The chemical diffusion coefficient of Cu2O has been obtained for an oxygen partial pressure near 5 10−4 atm as a function of the temperature in the range 700–900°C = 1 62 10−4 exp(−5140 ± 600 cal mol −1)/RT cm2s−1 This was easily achieved according to the electrochemical method used for the preparation of gaseous mixtures whose Po2; is lower than 10−5 atm The slight difference observed with the previously published results by Maluenda, and obtained for Po2 values which increase with T between 10−4 and 0.21 atm, may be due to an oxygen partial pressure effect already observed in the case of CoO. An ambipolar treatment of the chemical diffusion, in the case of p-type semiconductor MaOb, oxides, has allowed us to express the chemical diffusion coefficient as a function of the concentration of the prevailing defects and of their diffusion coefficient In the case where the prevailing defects are cationic vacancies α times ionized we have shown that the expression = (1 + α)Dvα can be generalized to the A2O compounds This set of results has allowed us, according to the copper self diffusion data obtained recently by Peterson et al, to estimate the apparent enthalpy of formation of the catiomc vacancies ΔHf 23 ± 0 8 kcal mol−1.
    Ogale, S.B., Bilurkar, P.G., Mate, N., Kanetkar, S.M., Parikh, N., and Patnaik, B.
    Deposition of copper oxide thin films on different substrates by pulsed excimer laser ablation 1992 Journal of Applied Physics
    Vol. 72, pp. 3765-3769 
    article DOI  
    Abstract: Stoichiometric films of cupric and cuprous oxide are deposited on Si, MgO, and Y-ZrO2 substrates by pulsed excimer laser ablation technique. It is found that the equilibrium phase diagram based considerations dictate the phase formation. The films are characterized by small-angle x-ray diffraction, infrared, and UV-visible spectroscopies and Rutherford backscattering spectroscopy. It is shown that epitaxy of Cu2O films can be realized on single crystal MgO (100) substrates and the corresponding film resistivity is of the order of 40–60 cm.
    Ogawa, K., Itoh, T., and Maki, K.
    Charge transfer from Cu in Cu2O epitaxially grown on MgO(001) by dc-reactive magnetron sputtering 2000 Physical Review B
    Vol. 62, pp. 4269-4272 
    article DOI  
    Ohyama, T., Ogawa, T., and Nakata, H.
    Determination of deformation-potential constants of Cu2O by microwave cyclotron resonance 1997 Physical Review B
    Vol. 56, pp. 3871-3874 
    article DOI  
    Abstract: We report on the temperature dependence of the cyclotron resonance in naturally grown Cu2O crystals. It is found that the temperature variation of the linewidths for both electrons and holes are well described by the sum of a temperature-independent term and one proportional to T3/2. From this experiment we deduce deformation-potential constants of De=2.4eV for electrons and Dh=2.2eV for holes.
    Okada, T. and Uno, R.
    On the Inner Photo-Effect of Cuprous Oxide 1949 Journal of the Physical Society of Japan
    Vol. 4(4), pp. 351 
    article DOI  
    Okada, M., Vattuone, L., Moritani, K., Savio, L., Teraoka, Y., Kasai, T., and Rocca, M.
    Pressure and temperature dependence of cuprous oxide nucleation on Cu(410) 2007 Journal of Physics Condensed Matter
    Vol. 19, pp. 305022 
    article DOI  
    Abstract: We studied the oxidation of Cu(410) during thermal O2 exposure using high-resolution electron energy-loss spectroscopy. Cu2O is identified by loss peaks at 19 and 79 meV. By monitoring the intensity of the latter, we find that Cu2O formation depends strongly on the surface temperature and on the O2 pressure and is kinetically limited by the impinging O2 flux. Thermally activated step roughening, leading to detachment of Cu adatoms from the step edge, acts as a source of mobile Cu atoms, allowing for subsequent nucleation of Cu2O patches.
    Okamoto, I., Takemoto, T., Mizutani, M., and Mori, I.
    Physical meaning of Wetting Curve Traced by Meniscograph Wettability Tester (Report II) 1985 Transactions of JWRI
    Vol. 14, pp. 201-207 
    inproceedings URL 
    Okamoto, Y., Ishizuka, S., Kato, S., Sakurai, T., Fujiwara, N., Kobayashi, H., and K., A.
    Passivation of defects in nitrogen-doped polycrystalline Cu2O thin films by crown-ether cyanide treatment 2003 Applied Physics Letters
    Vol. 82, pp. 1060-1062 
    article DOI  
    Abstract: Crown-ethercyanidetreatment,whichsimplyinvolvesimmersioninKCNsolutionscontaining
    Okazaki, A., Tubota, H., and Suzuki, H.
    The Temperature Dependence of the Zero Bias Resistance of Cuprous Oxide Rectifiers 1953 Journal of the Physical Society of Japan
    Vol. 8(3), pp. 431-432 
    article DOI  
    Okubo, N. and Igarashi, M.
    $^63$Cu Nuclear Quadrupole Relaxation in Cu2O 1999 Physica Status Solidi (b)
    Vol. 215(2), pp. 1109-1118 
    article DOI  
    Abstract: 63Cu nuclear spin-lattice relaxation time has been measured from 4.2 to 420 K. The result is analyzed with a theory of the Raman process based on covalency. By the fitting a value of 123.2 K is obtained for the Debye temperature, in contrast to the values of 180 to 190 K reported from other experiments. Then, a measure of covalency of the Cu-O bond is also calculated to be smaller by a factor of five than another measure of covalency calculated from the resonance frequency. These are attributed to the lattice instability and inappropriate value of the repulsive range parameter. It is concluded that the first-order Raman process due to covalency contributes significantly to the relaxation in Cu2O.
    Olbrychski, K., Kolodziejski, R., Suffczyski, M., and Kunert, H.
    Selection rules for the space group of Cu2O, at four symmetry points of the Brillouin zone 1975 Journal de Physique
    Vol. 36(10), pp. 985-990 
    article DOI  
    Olsen, L.C. and Bohara, R.C.
    Experimental and Theoretical Studies of Cu2O Schottky Barrier Solar Cells 1975 Proceedings of the 11th IEEE Photovoltaic Specialists Conference, pp. 381-390  inproceedings  
    Abstract: Thin-film Schottky barriers based on Cu2O are being investigated for low-cost photovoltaic energy conversion. Current-voltage (I-V), capacitance-voltage (C-V) and photoresponse studies have been made with thermally grown, backwall Cu/Cu2O devices. I-V characteristics are explained very well with n-values typically greater than 2. As a result, it appears that Cu/Cu2O cells have a MIS structure. C-V data also imply a MIS configuration. Solar cell calculations have been carried out for Cu2O devices based on a MIS model. Calculations indicate that by utilizing MIS structures, power conversion efficiencies over 10% constitute reasonable goals for both frontwall and backwall cells.
    Olsen, L.C. and Bohara, R.C.
    Explanation of low barrier heights obtained for Cu2O Schottky barrier solar cells 1978 Proceedings of the 13th IEEE Photovoltaic Specialists Conference, pp. 1251-1252  inproceedings  
    Abstract: Depth-concentration Profiles obtained with
    Auger electron spectroscopy are reported for
    Yb/Cu& Mg/Cu,O and Au/Cu10 contacts. The
    profiles for Yb/CuzO and Ng/Cu20 cells indicate
    that the Cu20 surface is reduced upon metal
    deposition, and that considerable Interdiffusion
    occurs at the interface. As a result, a copper-
    rich layer appearc to exist at the Cu20 interface
    in these Schottky barriers formed with low work
    function metals. On the other hand, the Au/Cu20
    interface exhibits a'more "normal" structure.
    These results are utilized to explain the rel-
    atively low barrier heights obtained for Cu20
    Schottky barriers, and the apparent "efficiency
    plateau" of 1% for Cu20 solar cells. The results
    are also compatible with the fact that Au forms
    essentially an ohmic contact on Cu,O.
    Olsen, L.C., Bohara, R.C., and Urie, M.W.
    Explanation for low-efficiency Cu2O Schottky-barrier solar cells 1979 Applied Physics Letters
    Vol. 34, pp. 47-49 
    article DOI  
    Abstract: Surface analyses combined with barrier-height studies indicate that Cu2O Schottky barriers made with low-work-function metals (Yb, Mg, and Mn) are essentially Cu/Cu2O cells due to reduction of the Cu2O surface and subsequent interdiffusion phenomena. The copper-rich region essentially determines the barrier height. As a result, efficiencies of Cu2O Schottky-barrier solar cells are usually less than 1%. It is concluded that to achieve significant increases in Cu2O cell efficiencies, MIS or heterojunction device structures must be utilized.
    Olsen, L.C., Addis, F.W., and Bohara, R.C.
    Investigation of Cu2O solar cells 1980 Proceedings of the 14th IEEE Photovoltaic Specialists Conference, pp. 462-467  inproceedings  
    Abstract: This paper includes discussion Of an approach
    used for cuzo substrate fabrication, electrical and
    optical properties of cu20,photocurrent analysis
    and experimental results for cuzo Solar cells. An
    AM1 photocurrent of 8.5 mA/cn? and AM1 efficiency
    of 1.8% has heen achieved for Cu-Cu$ MIS cells
    based on a tentatively identified I-layer of Cum.
    Studies Of MIS cells fabricated with an evaporated
    SO2 I-layer are discussed as well as preliminary
    results for Z~S/CUZO and 7.nO/Cu20 heterojunctions.
    Olsen, L.C., Addis, F.W., and Miller, W.
    Experimental and theoretical studies of Cu2O solar cells 1982 Solar Cells
    Vol. 7, pp. 247-279 
    article DOI  
    Abstract: Extensive studies of Cu2O Schottky barrier solar cells have been conducted. Schottky barrier devices based on metals characterized by a wide range of work functions have been investigated. Cell characterization includes electro-optical studies, thermodynamic considerations concerning interface stability and depth-concentration profiles. Cu/Cu2O cells were develope that exhibited active-area air mass 1 values of photocurrent and efficiency of 8.5 mA cm−2 and 1.8% respectively. A detailed photon and carrier loss analysis conducted for Cu/Cu2O cells is used to project the ultimate values of the photocurrent for Cu2O cells to be 12 – 14 mA cm−2. Thermodynamic considerations indicate that thallium is the only metal which can be combined with Cu2O to yield an adequate efficiency. However, Tl/Cu2O Schottky barrier cells exhibit properties similar to Cu/Cu2O devices. Depth-concentration profiles show that, although no Tl---O bonding exists in the interfacial region, the region is copper rich. It is concluded that the oxygen deficiency occurs because of preferential sputtering of oxygen during the thallium deposition process. As a result of these Cu2O Schottky barrier studies, it is concluded that significant improvements in the efficiency of Cu2O solar cells can be achieved only with a homojunction structure. Thus, an approach to doping Cu2O n type must be developed in order for the potential of this material for low cost photovoltaics to be realized.
    Onimisi, M.Y.
    Effect of annealing on the resistivity of copper (I) oxide solar cells 2008 International Journal of Physical Sciences
    Vol. 3, pp. 194-196 
    article URL 
    Abstract: The effect of annealing on the resistively of copper (I) oxides (Cu2O) samples has been investigated in detail. The resistivily of the sample is a function of the power output of such Cu2O solar cell. Results revealed that the annealing of Cu2O samples improves the output performance compared to that of unannealed samples by about 36%. The results on the resistivity of the samples oxidized at different temperatures for different times but annealed for some duration at an identical temperature after proper quenching in deionizer water shows a lower and higher resistivities for annealed and unannealed samples respectively.
    Ono, M.
    On the Deviation from the Ohm's Law at the Anode Surface of the Cuprous Oxide Rectifiers 1951 Journal of the Physical Society of Japan
    Vol. 6(5), pp. 397A 
    article DOI  
    Önsten, A., Månsson, M., Claesson, T., Muro, T., Matsushita, T., Nakamura, T., Kinoshita, T., Karlsson, U.O., and Tjernberg, O.
    Probing the valence band structure of Cu2O using high-energy angle-resolved photoelectron spectroscopy 2007 Physical Review B
    Vol. 76, pp. 115127 
    article DOI  
    Abstract: We present angle-resolved photoemission data along the M-Γ-M direction from a Cu2O(111) single crystal, collected at high photon energies (hν=619 and 891 eV) and T=100 K. Because of the high photon energies and effective background subtraction, our data give a clear picture of the bulk band structure. The results confirm the existence of a hybridized Cu 3d–Cu 4s state located between the two main Cu 3d and O 2p band regions. Several theoretical studies have predicted the existence of this band, but until now it has not been detected in any photoemission measurements. The experimentally derived band structure is compared to local density approximation calculations with and without the Hubbard potential U. The clear band dispersion in our experimental data has enabled us to extract a refined Hubbard U value, which makes it possible to achieve a better agreement between theoretically calculated bands and experimental data.
    Dispositif supraconducteur opto--électronique à base de Cu2O à photoconductivité et supraconductivité conjuguées 1997 (0456513)  patent  
    Otter, M.
    Lifetime of Paraexcitons in Cuprous Oxide 2007 School: University of Groningen, Faculty of Mathematics and Natural Sciences  mastersthesis URL 
    Ottosson, M. and Carlsson, J.-O.
    Chemical vapour deposition of Cu2O and CuO from CuI and O2 or N2O 1996 Surface and Coatings Technology
    Vol. 78(1-3), pp. 263-273 
    article DOI  
    Abstract: Thin films of CuO and Cu2O were deposited from CuI as the copper source and O2 or N2O as the oxygen source. If O2 was used, both CuO and Cu2O were obtained. Cu2O was deposited at low O2 partial pressures (Po2 < 0.2 Torr) in a long isothermal hot wall chemical vapour deposition (CVD) reactor (T=500 �C). The CuO phase was obtained at a certain position in the CVD reactor and a sudden maximum in the deposition rate was then reached. The maximum was attributed to a change in the deposition mechanism upon the formation of CuO. When I2 was added to the reaction gas mixture, the maximum disappeared and the deposition rate increased. The formation of CuO was also investigated thermodynamically. For higher [I2]/[CuI] ratios, the CuO phase was stable, even at a low O2 pressure. Cu2O films were also deposited with N2O as the oxygen source. At 650 �C and with an excess of CuI, the deposition rate was found to be controlled by the decomposition of N2O. Above a linear gas flow velocity of 70 cm s-1, the deposition rate was constant, which indicated a surface-controlled process.
    Papadimitriou, L., Economou, N.A., and Trivich, D.
    Heterojunction Solar Cells On Cuprous Oxide 1981 Solar Cells
    Vol. 3, pp. 73-80 
    article DOI  
    Abstract: Heterojunction solar cells were made on Cu2O by sputtering In2O3, SnO2, CdO and mixtures of CdO and SnO2 and by thermal evaporation of ZnSe. Photovoltaic effects were observed in most cases. High series resistances were an indication of chemical reactions at the interface. Auger surface analysis showed evidence of copper metal at the interface, arising from chemical reactions. For a CdO/Cu2O junction formed at room temperature, no copper metal was found at the interface. The CdO/Cu2O cells showed Voc = 0.4 V and Isc = 2 mA cm−2. The properties appear to be dominated by a multiple-step tunneling at the junction, presumably due to dislocations and impurities in the Cu2O samples as prepared.
    Papadimitriou, L., Economou, N.A., and Trivich, D.
    Photovoltaic properties of sputtered $n$-CdO films on $p$-Cu2O 1983 Solid-State Electronics
    Vol. 26(8), pp. 767-769 
    article DOI  
    Abstract: The heterojunction CdO/Cu2O was prepared by sputtering CdO films on Cu2O at room temperature. The optical transmission of CdO films at a thickness of [approximate]1000 � was [approximate]85%. The analysis of the I-V characteristics at different temperatures gave information of the carrier transport mechanism at the junction. The forward and the reverse dark current is dominated by a tunneling process. Measurements of the open-circuit photovoltage resulted in a curve which indicates a sensitivity range from 2.25 to 2.48 eV, similar to that found in Cu2O MIS solar cells.
    Papadimitriou, L. and Economou, N.A.
    Preparation of bulk single crystals of Cu2O by the plastic flow method and investigation of their electrical properties 1983 Journal of Crystal Growth
    Vol. 64(3), pp. 604-608 
    article DOI  
    Abstract: Bulk single crystals of Cu2O were prepared with the plastic-flow method. Electrical measurements indicated that this method gives crystals with lower resistivity. Doping with cadmium produced crystals of resistivities down to 77 [Omega] cm. The properties of the crystals can be explained by a model which is based on partial charge compensation and which is consistent with the cadmium doped material being heavily compensated.
    Papadimitriou, L.
    Schottky barriers on Cu2O and their performance as solar cells 1984 Proceedings of the 5th Bulgarian--Greek Symposium in Semiconductors, Sofia, pp. 126-130  inproceedings  
    Papadimitriou, L., Dimitriadis, C.A., and Dozsa, L.
    Trap Centers in Cuprous Oxide 1988 Solid-State Electronics
    Vol. 31, pp. 1477-1482 
    article DOI  
    Abstract: The effect of annealing temperature on the trap density in Cu2O is investigated. From space charge limited current (SCLC), Hall effect and DLTS measurements it is demonstrated that there is a trap-band distribution with the Fermi level lying within the trap-band. The maximum of this trap-band distribution is just above the Fermi level. A theoretical model is introduced to explain this trap-band distribution. Annealing of the samples in air at 400–500°C for 5 h gives the lowest total trap concentration and the lowest resistivity of the material. The above annealing decreases the total number of traps by a factor of 3 compared to the as grown samples. The resistivity decreases also by at least one order of magnitude.
    Papadimitriou, L., Valassiades, O., Manolikas, K., Stoemenos, J., Spyridelis, J., and Economou, N.A.
    High-temperature phases of YBa2Cu$_3$O$_6+x$ related to the superconducting transition 1988 Journal of Materials Science Letters
    Vol. 7(5), pp. 489-492 
    article DOI  
    Papadimitriou, L., Dimitriadis, C.A., Dozsa, L., and Andor, L.
    Deep Trap Levels in Cuprous Oxide 1989 Solid-State Electronics
    Vol. 32, pp. 445-448 
    article DOI  
    Abstract: The effect of the annealing temperature and doping with cadmium on the deep trap levels in Cu2O is considered here. From photoluminescence and C-V (admittance spectroscopy) measurements it is demonstrated that in the energy gap of the undoped material there are deep traps at the energy levels 0.72, 1.19 and 1.33 eV from the valence band edge. Annealing of the samples in air at 500°C for 5 h decreases the concentration of the traps 1.19 and 1.33 eV, by a factor of 50. The origin of these two trap levels is singly and doubly ionized oxygen vacancies which are partially filled with the annealing. Doping with Cd decreases the trap concentration of these two trap levels by a factor of 7 and annealing of the doped material at 500°C in air removes completely these two trap levels. However, in the Cd-doped material a new trap appears at the energy level 0.90 eV from the valence band edge.
    Papadimitriou, L.
    Acceptor States Distributed In Energy In Cd--doped Cu2O 1989 Solid State Communications
    Vol. 71, pp. 181-185 
    article DOI  
    Papadimitriou, L.
    DLTS Evaluation of nonexponential transients of defect levels in cuprous oxide (Cu2O) 1993 Solid-State Electronics
    Vol. 36, pp. 431-434 
    article DOI  
    Abstract: The DLTS nonexponential transients of the Schottky barrier Cu/Cu2O are investigated. The DLTS spectra are due to acceptor states distributed in energy and their origin is attributed to structural anomalies and “islands” of CuO in the material. The analysis, based on a weak disordered Gaussian distribution of the acceptor states, gives real values of the activation energy E0 and the capture cross section, which are smaller than the ones determined from standard DLTS analysis. A small deviation from the Gaussian distribution was observed for temperatures higher than the one corresponding to the peak of the DLTS signal. This is attributed to a small assymetry of the trap-band distribution with respect to the maximum of the trap-band. The maximum concentration of the trap-band distribution is located above the Fermi level. The above observations are true only for a sample which was annealed at 500°C in air. The assymetry of the trap-band distribution is quite large for a sample annealed at 400°C. First results are presented and the need for a new model is emphasized for this case.
    Park, J.-H. and Natesan, K.
    Oxidation of Copper and Electronic Transport in Copper Oxides 1993 Oxidation of Metals
    Vol. 39, pp. 411-435 
    article DOI  
    Abstract: Oxidation of copper and electronic transport in thermally-grown large-grain polycrystals of nonstoichiometric copper oxides were studied at elevated temperatures. Thermogravimetric copper oxidation was studied in air and oxygen at temperatures between 350 and 1000°C. From the temperature dependence of the oxidation rates, three different processes can be identified for the oxidation of copper: bulk diffusion, grain-boundary diffusion, and surface control with whisker growth; these occur at high, intermediate, and low temperatures, respectively. Electrical-conductivity measurements as a function of temperature (350–1134°C) and oxygen partial pressure (10–8–1.0 atm) indicate intrinsic electronic conduction in CuO over the entire range of conditions. Electronic behavior of nonstoichiometric Cu2O indicates that the charge defects are doubly-ionized oxygen interstitials and holes. The calculated enthalpy of formation of oxygen ( ) and hole-conduction energy (EH) at constant composition for nonstoichiometric Cu2O are 2.0±0.2 eV and 0.82±0.02 eV, respectively.
    Parretta, A., Jayaraj, M.K., Di Nocera, A., Loreti, S., Quercia, L., and Agati, A.
    Electrical and Optical Properties of Copper Oxide Films Prepared by Reactive RF Magnetron Sputtering 1996 Physica Status Solidi (a)
    Vol. 155, pp. 399-404 
    article DOI  
    Abstract: Copper oxide thin films were prepared by reactive rf magnetron sputtering of a pure copper target in an oxygen-argon atmosphere. The phases of the deposited films strongly depend on the oxygen content in the sputtering gas. X-ray diffraction studies show that by controlling the oxygen partial pressure single phase Cu2O and CuO can be obtained. The resistivity of the Cu2O film in the present study is 43 cm. The optical constants were evaluated from transmission and reflection measurements.
    Pastrňák, J. and Kužel, R.
    Влияние освещения на проводимость и фотопроводимость з акиси меди 1956 Czechoslovak Journal of Physics
    Vol. 6(3), pp. 217-235 
    article DOI  
    Abstract: ? ?????? ????????, ??? ??? ?????????? ????? ??? Cu2O?? ?????-?????? 130–200 °C?? ????????????? ????? ??????????? ?? ????-????????? ??????????? ??????? ?. ??? ?????????? ???? ???????? ????? ?????????????. ?? ??? ??????????? ??????? ??? ? ????????? ?????-??? ????????? f???????? ???????. ?????????? ? ???????????? ????? ??????????, ??? ? ????????? ??????, ?? ???????????????, ??? ??f???? ??????????? ???? ???????, ??????? ?????????? ?????-??? ????????????, ?????? ??? ?????????? ? ???? ??????? ????????? ????? ????????????? ??? ??????????? ? ??? ?????????????? ???-? ????. ??? ????????? ?????? ???? ????????? ????? ??????? ?????-???? ? ??????? ?????????? ?????? ???????. ????? ?????????? ???-????? ? ??????????????? ? ?? ??????? f?????????? ????? ??? ???????.
    Pastrňák, J. and Kužel, R.
    The influence of illumination on the conductivity and photo-conductivity of Cu2O 1956 Czechoslovak Journal of Physics
    Vol. 6, pp. 235 
    article DOI  
    Pastrňák, J.
    Temperature Dependence of Light Absorption in Cuprous Oxide Crystals in the Visible Region of the Spectrum 1959 Soviet Physics - Solid State
    Vol. 1, pp. 888-891 
    Pastrňák, J.
    Refractive index of Cu2O crystals in region up to $10$textmu 1961 Czechoslovak Journal of Physics
    Vol. 11(5), pp. 374-376 
    article DOI  
    Pastrňák, J.
    Спектральное распре деление квантового в ыхода инфракрасной люмине сценции Cu2O при низких температурах 1961 Czechoslovak Journal of Physics
    Vol. 11(6), pp. 452-453 
    article DOI  
    Paul, G.K., Nawa, Y., Sato, H., Sakurai, T., and Akimoto, K.
    Defects in Cu2O studied by deep level transient spectroscopy 2006 Applied Physics Letters
    Vol. 88, pp. 141901 
    article DOI  
    Abstract: Hole traps in p-type Cu2O were studied by means of deep level transient spectroscopy in the heterostructure of p-Cu2O/i-ZnO/n-ZnO. In addition to the trap level at about 0.45 eV from the valance band edge, which is already reported as being due to Cu vacancy, we found a new trap level at about 0.25 eV. The new trap is tentatively assigned as Cu-di-vacancy from the trap concentration dependence on oxygen flow rate and substrate temperature.
    Paul, G.K., Ghosh, R., Bera, S.K., Bandyopadhyay, S., Sakurai, T., and Akimoto, K.
    Deep level transient spectroscopy of cyanide treated polycrystalline p-Cu2O/n-ZnO solar cell 2008 Chemical Physics Letters
    Vol. 463, pp. 117-120 
    article DOI  
    Abstract: Deep levels in polycrystalline p-Cu2O/i-ZnO/n-ZnO/glass photovoltaic structures were studied by deep level transient spectroscopy (DLTS). Post-deposition crown-ether cyanide (CN) treatments of the samples were performed with the variation of time. DLTS spectra for all samples showed the presence of two traps localized at 0.2 eV and 0.5 eV from the top of the valence band. Effects of defect passivation and improvement of cell performance were demonstrated with the cyanide treated samples. Optimum time of cyanide treatment was found to be 3 min. Cell performance was increased from 0.4% to 0.7% for the samples undergoing the optimum post-deposition cyanide treatment.
    Pearson, G.L. and Brattain, W.H.
    History of Semiconductor Research 1955 Proceedings of the IRE
    Vol. 43(12), pp. 1794-1806 
    inproceedings DOI  
    Pedocchi, L., Billi, A., Marinelli, E., Wu, J.X., and Rovida, G.
    ESCA study of the oxidation of DHP copper 1992 Surface and Interface Analysis
    Vol. 19(1-12), pp. 414-418 
    article DOI  
    Abstract: The surface composition of deoxidized high phosphorus (DHP) copper sheets was investigated by ESCA with the aim of verifying the role of phosphorus in oxide formation. While no surface segregation of phosphorus was observed on samples cleaned by ion bombardment and annealing in ultrahigh vacuum, the presence of large amounts of phosphorus was found after the formation of the oxide by exposure to 0.1 Torr oxygen at 770 K. The surface enrichment in P with the same binding energy was found after annealing a sheet of DHP copper coated with a layer of Cu2O deposited by sputtering. The binding energy of the P 2p peak as well as the analysis of the components of O 1s can be interpreted with the formation of a metaphosphate. Experiments performed at intermediate temperatures showed that the segregation of phosphorus is appreciable above 600 K and appears to be related to oxygen diffusion into the bulk.
    Perakis, N. and Serres, A.
    Étude de la semi-conductivité de l'oxyde cuivreux d'après son comportement magnétique entre $80$ et $1000K$ 1955 Journal de Physique et Le Radium
    Vol. 16, pp. 387-394 
    article DOI  
    Abstract: Libre d'impuretés ferromagnétiques et de CuO, l'oxyde cuivreux utilisé contenait un excès d'oxygène de 0,9 pour 100 environ, exprimé en vacances cuivre, |Cu +|, dans la formule CU11 |Cu+| O6. Cet édifice lacunaire est un semi-conducteur du type p, la vacance Cu + et la vacance d'électron (trou positif), que nous avons située dans la bande 3d du cuivre, figurant respectivement l'impureté et l'élément conducteur. Étudié entre 80 et 1000° K, l'oxyde possède un paramagnétisme variable, χi, auquel se superpose un faible diamagnétisme, ou paramagnétisme constant χr, dû au reste de la molécule. χr change de valeur et de signe d'une expérience à l'autre, avec le contenu en vacances gelées du reste de la molécule. Au-dessus de 360° K, le paramagnétisme variable est exprimé par la relation de Curie 10-4χ i T = 1,06(± 0,04), la constante 1,06.10-4 mesurant le paramagnétisme de Curie d'un gramme d'oxyde. Excluant toute liaison antiferromagnétique, possible entre ions Cu++, cette relation de Curie semble montrer que, dans le domaine d'impureté, il y a deux porteurs de moment, les ions Cu++ et |Cu+|-, en nombre égal, pour un porteur de charge, la vacance d'électron. Toutefois, le porteur Cu++ , directement lié au trou, est d'origine stoechiométrique. Admettant la validité de la loi de Curie entre 80 et 1000° K, nous avons calculé dans tout cet intervalle de température, à partir de 1/2χi T, le nombre de trous par centimètre cube. Ce nombre, croissant depuis 80° K, ne varie plus au-dessus de Θ ≈ 360°K, sa valeur maximum, 5,1.1020, correspondant à 1/9 de l'excès d'oxygène incorporé. Θ apparaît comme la température à laquelle il faut élever le cristal pour le saturer en centres d'impureté. Il semble que la recombinaison de trous et d'électrons ait lieu à la surface (qui change de couleur) de la masse d'oxyde.
    Perinet, F., Barbezat, S., and Monty, C.
    New investigation of oxygen self-diffusion in Cu2O 1980 Journal de Physique Colloques
    Vol. 41, pp. C6-315-C6-318 
    article DOI  
    Abstract: New measurements of oxygen self-diffusion coefficients in Cu2O have been performed on single crystals under two oxygen partial pressures (4.6 x 10-4 atm and 0.26 atm) in the stability domain. The stable isotope 18O has been used as a tracer. It has been introduced by a thin film method or by annealing under a constant 18O pressure. The diffusion profiles have been measured by secondary ion mass spectrometry. They obey quite well the solutions of Fick's equation. The results can be represented by : D (cm2 .s-1) = 3 x 10-3 p0,4 O2 exp - 1,55 (eV)/ kT. The defect responsible for the oxygen migration corresponding to the above oxygen partial pressure dependence is the singly charged oxygen interstitial O'i.
    Perinet, F., Barbezat, S., and Philibert, J.
    ``Mechanism of Oxygen Self-Diffusion in Cu2O'' in Synthetic Materials for Electronics (Materials Science Monographs) 1982
    Vol. 10, pp. 234 
    Perinet, F., Le Duigou, J., and Monty, C.
    ``Oxygen diffusion in volume and in grain-boundaries of Cu$_2-x$O'' in Non Stoichiometric Compounds: Surface, Grain Boundaries and Structural Defects (NATO Science Series C) 1989 , pp. 387-397  inbook  
    Peterson, N.L. and Wiley, C.L.
    Diffusion and Point Defects in Cu2O 1984 Journal of Physics and Chemistry of Solids
    Vol. 45, pp. 281-294 
    article DOI  
    Abstract: The diffusion of64Cu in Cu2O has been measured by a serial-sectioning technique as a function of temperature (700–1153°C) and oxygen partial pressure (10−6−8 × 102&#x0304; atm). The oxygen-partial-pressure and temperature dependencies of D*Cu suggest that both neutral and singly charged copper vacancies contribute to cation self-diffusion. A defect model involving both neutral and singly charged copper vacancies, electron holes, and singly charged oxygen-interstitial ions is developed and fit to the tracer-diffusion data, the electrical-conductivity data (Maluenda et al.), and the stoichiometry data (O'Keeffe and Moore). The resulting defect data are quantitatively consistent with the chemical-diffusion data (Maluenda et al.) and with a correlation factor . The defect data are also quantitatively consistent with the high-temperature oxidation studies of copper metal (Iguchi et al.) and with the copper vacancy being 10 times more mobile than the oxygen-interstitial ion at 1000†C.
    Petroff, Y., Yu, P.Y., and Shen, Y.R.
    Study of photoluminescence in Cu2O 1975 Physical Review B
    Vol. 12, pp. 2488-2495 
    article DOI  
    Pfund, A.H.
    The Light Sensitiveness of Copper Oxide 1916 The Physical Review (second series)
    Vol. 7, pp. 289-301 
    article DOI  
    Pierson, J.F., Thobor-Keck, A., and Billard, A.
    Cuprite, paramelaconite and tenorite films deposited by reactive magnetron sputtering 2003 Applied Surface Science
    Vol. 210, pp. 359-367 
    article DOI  
    Abstract: Copper oxides films (Cu2O, Cu4O3 and CuO) have been deposited by magnetron sputtering of a copper target in various Ar–O2 reactive mixtures. The films are characterized by X-ray diffraction, scanning electron microscopy, four-point probe method and UV-Vis spectrometry. The three defined compounds in the Cu---O binary system can be deposited by varying the oxygen flow rate introduced into the reactor. All the films are crystallized with a mean crystal size ranging from 10 to about 35 nm. They are highly resistive and present a direct optical band gap higher than 2 eV. The application of a bias voltage during the deposition phase modifies the texture of the Cu2O films and also induces a preferential resputtering of oxygen from the Cu4O3 ones. This resputtering phenomenon leads firstly to the occurrence of the cuprite phase mixed with the paramelaconite one and secondly to the amorphisation of the films. Finally, the thermal stability in air of cuprite, paramelaconite and tenorite films has been investigated. The results show that the stability of Cu2O and Cu4O3 films in air is influenced by the thickness and/or the texture of the films. Tenorite films with a low optical band gap (1.71 eV) can be formed after air annealing at 350 °C of an unbiased cuprite film.
    Pinkas, J., Huffman, J.C., Baxter, D.V., Chisholm, M.H., and Caulton, K.G.
    Mechanistic Role of H2O and the Ligand in the Chemical Vapor Deposition of Cu, Cu2O, CuO, and Cu$_3$N from Bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(II) 1995 Chemistry of Materials
    Vol. 7(8), pp. 1589-1596 
    article DOI  
    Poizot, P., Hung, C.-J., Nikiforov, M.P., Bohannan, E.W., and Switzer, J.A.
    An Electrochemical Method for CuO Thin Film Deposition from Aqueous Solution 2003 Electrochemical and Solid-State Letters
    Vol. 6(2), pp. C21-C25 
    article DOI  
    Pollack, G.P. and Trivich, D.
    Photoelectric properties of cuprous oxide 1975 Journal of Applied Physics
    Vol. 46, pp. 163-172 
    article DOI  
    Abstract: The effects of transient and steady−state illumination on the electrical properties of single−crystal cuprous oxide have been investigated in the temperature range from 230 to −20 °C. For samples equilibrated well within the region of Cu2O stability, conduction was governed by an acceptor level at 0.4 eV above the valence band as determined from the temperature dependence of the Hall effect. The presence of two minority carrier trapping levels was also established and trapping parameters were determined from an analysis of the transient photoconductivity. The 0.4−eV acceptor level was also found to be present in a sample equilibrated under conditions placing its composition in a region near the CuO−Cu2O phase boundary. For this sample, however, only a single deeper trapping level was observed. A third type of sample, equilibrated under conditions which placed its composition in a region near the Cu−Cu2O phase boundary, was characterized by both a high hole density and a high mobility with an acceptor level energy of 0.16 eV. Also, the presence of two effects, the thermal quenching of the steady−state photoconductivity and its nonlinear dependence on light intensity, were shown to be consistent with the presence of deep traps in this material.
    Porat, O. and Riess, I.
    Defect chemistry of Cu$_2-y$O at elevated temperatures. Part I: Non-stoichiometry, phase width and dominant point defects 1994 Solid State Ionics
    Vol. 74, pp. 229-238 
    article DOI  
    Abstract: The deviation from stoichiometry in Cu2−yO was measured as a function of oxygen partial pressure, 10−13≤PO2≤0.1 atm, and temperature, 873≤T≤1245 K, using a solid state electrochemical method. The measurements covered the whole width of the phase Cu2−yO for the temperature range 873≤T≤1245 K. The y−PO2−T relations are analyzed in order to identify the dominant point defects. It is found that in the high PO2 range of the phase, the dominant defects are neutral copper vacancies, VxCu. In the low PO2 range there are two types of defects, dominating at different temperatures. At low temperatures the dominant defects are neutral copper interstitials, Cuxi. The analysis indicates that at temperatures higher than 1245 K the dominant defects are oxygen vacancies, VxO. The enthalpy and entropy for the formation of VCux and Cuix are also determined.
    Porat, O. and Riess, I.
    Defect Chemistry of Cu$_2-y$O at elevated temperatures. Part II: Electrical conductivity, thermoelectric power and charged point defects 1995 Solid State Ionics
    Vol. 81, pp. 29-41 
    article DOI  
    Abstract: The electrical conductivity and the Seebeck coefficient of Cu2O were measured as a function of temperature and oxygen partial pressure. The measurements were performed between 900 K and 1300 K and between 10−12 atm and 0.15 atm. The results indicate that the dominant electronic charge carriers are holes, although at high temperatures ( 1200 K) and low oxygen partial pressure ( 10−5 atm) there is also a significant contribution of electrons to the electrical conductivity and Seebeck coefficient. The dominant ionic point defects are doubly charged oxygen interstitials O″i, dominating at temperatures above 1150 K, and singly charged copper vacancies V′cu, dominating at temperatures below 950 K. The values of the enthalpy and entropy for the formation of the charged defects were found. The mobility values of holes and electrons were determined in the temperature range of 1000 K T 1250 K. The hole mobility is 3 , vh 6 cm2/Vs, and it decreases when the temperature increases. The electron mobility is higher than that of holes, with values of 150 ve 200 cm2/Vs. The variation of the Fermi level within the Cu2O phase as a function of oxygen partial pressure and temperature was also determined.
    Pouillon, Y., Massobrio, C., and Celino, M.
    Neutral and anionic CuO2: an ab initio study 2000 Computational Materials Science
    Vol. 17(2-4), pp. 539-543 
    article DOI  
    Abstract: By using first-principles calculations within density functional theory via the local density approximation (LDA) and the generalized-gradient approximation (GGA) of Perdew and Wang for exchange and correlation, we calculate the equilibrium structures of CuO2 and CuO2- clusters. In the case of CuO2, three isomers (OCuO linear and two CuO2 complexes, side-on and bent) lie within 0.5 eV, while the negatively charged cluster is most stable as a linear molecule. Our assignment of measured photo-electron spectra features on the basis of the electronic density of states (EDOS) suggests that the bent structure is the most stable among the two forms of CuO2- complexes.
    Pradère, F., Mysyrowicz, A., Rustagi, K.C., and Trivich, D.
    Two-Photon Absorption in Cu2O Due to Transitions to Higher-Energy Excitons 1971 Physical Review B
    Vol. 4(10), pp. 3570-3572 
    article DOI  
    Abstract: The two-photon absorption spectrum of Cu2O is measured at 77°K in the frequency range corresponding to transitions between bands of opposite parity. The main features are well explained on the basis of existing theories. However, we also observe an additional structure associated with the 1s exciton which lies on a strongly interfering continuum. Using Fano's theory of configuration interaction, we estimate the auto-ionization lifetime of the 1s exciton to be ∼10-14 sec.
    Prakash, I., Muralidharan, P., Nallamuthu, N., Venkateswarlu, M., and Satyanarayana, N.
    Preparation and characterization of nanocrystallite size cuprous oxide 2007 Materials Research Bulletin
    Vol. 42(9), pp. 1619-1624 
    article DOI  
    Abstract: Uniform spheres of nanocrystallite size cuprous oxide particles have been prepared by a simple polyol process using cupric nitrate as a precursor in ethylene glycol. As synthesized compound was dried at 333 K in a vacuum oven and characterized by XRD, FT-IR and SEM techniques. The crystallite size of the cuprous oxide calculated from Scherer's formula was found to be ~11 nm.
    Prevot, B., Carabatos, C., and Sieskind, M.
    Near Infrared Optical and Photoelectric Properties of Cu2O. I. Infrared Absorption in Cu2O after Annealing in Oxygen or He$^+$ Particles Bombardments 1972 Physica Status Solidi (a)
    Vol. 10, pp. 455-463 
    article DOI  
    Prisedsky, V.V. and Vinogradov, V.M.
    Fragmentation of diffusion zone in high-temperature oxidation of copper 2004 Journal of Solid State Chemistry
    Vol. 177, pp. 4258-4268 
    article DOI  
    Abstract: Using thermogravimetry, microscopy and X-ray diffraction, high-temperature (600-900 °C) oxidation of copper wires and plates has been studied. An abrupt decrease in reaction rate after complete consumption of metal phase but long before reaching equilibrium has been observed. This phenomenon is connected to an irregular character of the development of the reaction diffusion zone. In contrast to the usually applied layer model, initially formed oxide layers separate into numerous aggregates of Cu2O crystals chaotically scattered throughout the zone between thinner layers of CuO grains. Such fragmentation of the diffusion zone is induced by macro- and microcracks formed in copper scale under influence of mechanical stresses at metal-oxide phase boundary due to the difference in molar volume between copper and its oxides. The pattern of cracks provides channels of fast diffusion and maintains the reaction rate at high level but only until the source of crack formation remains in action.
    Raebiger, H., Lany, S., and Zunger, A.
    Origins of the $p$-type nature and cation deficiency in Cu2O and related materials 2007 Physical Review B
    Vol. 76, pp. 045209 
    article DOI  
    Abstract: While most of crystalline wide gap oxides are both stoichiometric and insulating, a handful of them including ZnO and In2O3 are naturally anion-deficient and electron conductors. Even fewer of the oxides are naturally cation-deficient and hole conductors, the arch-type of which is Cu2O. Based on first principles calculation of equilibrium nonstoichiometry and defect stability, we explain why the Cu(I)(d10) oxide-based materials are both p-type and naturally cation-deficient, and why cation vacancies lead to delocalized, conductive states, whereas in other oxides (e.g., ZnO and MgO), they lead to localized, nonconductive states.
    Raebiger, H., Lany, S., and Zunger, A.
    Impurity Clustering and Ferromagnetic Interactions that are not Carrier Induced in Dilute Magnetic Semiconductors: The Case of Cu2O:Co 2007 Physical Review Letters
    Vol. 99(16), pp. 167203 
    article DOI  
    Abstract: Current models for ferromagnetism in diluted magnetic semiconductors, such as “p-d exchange” or “double-exchange”, rely on the presence of partially filled gap states. We point out a new mechanism, not requiring partially filled states, in which ferromagnetic coupling arises from the occupation of previously unoccupied levels when two transition metal impurities form a close pair. We find from first-principles calculations that this mechanism explains strong ferromagnetic coupling between Co impurities in Cu2O, and at the same time gives rise to Co clustering.
    Rafea, M.A. and Roushdy, N.
    Determination of the optical band gap for amorphous and nanocrystalline copper oxide thin films prepared by SILAR technique 2009 Journal of Physics D: Applied Physics
    Vol. 42(1), pp. 015413 
    article DOI  
    Abstract: Amorphous copper oxide films were deposited using the SILAR technique. Both Cu 2 O and CuO crystallographic phases exist in deposited and annealed films. Crystallization and growth processes by annealing at temperatures up to 823 K form grains with nano- and micro-spherical shapes. The calculated crystallite size from the XRD measurement was found to be in the range 14–21 nm while nano-spheres in the diameter range 50–100 nm were observed by SEM micrographs. The band gap for amorphous film was found to be 2.3 eV which increased slowly to 2.4 eV by annealing the film at 373 K. This was explained by defect redistribution in amorphous films. Annealing in the temperature range 373–673 K decreased the band gap gradually to 1.85 eV. The decrease of the band gap with annealing temperature in the range 373–673 K agrees well with the Brus model of the energy gap confinement effect in nanostructured semiconducting materials. Annealing in the temperature range 673–823 K decreases the band gap slowly to 1.7 eV due to the smaller contribution of the confinement effect. Below 573 K, Cu 2 O is the most probable crystalline phase in the film, while Cu 2 O and CuO crystalline phases may coexist at annealing temperatures above 573 K due to further oxidation of Cu 2 O. A wider transmittance spectral window in the visible region was obtained by controlling the annealing conditions of the amorphous copper oxide film and its applicability to the window layer of solar cell was suggested.
    Rai, B.P.
    Cu2O Solar Cells: A Review 1988 Solar Cells
    Vol. 25, pp. 265-272 
    article DOI  
    Abstract: The status of Cu2O solar cells is reviewed. Cu2O is a potential material for the fabrication of solar cells for terrestrial application particularly as the top cell in a cascade cell structure. The technological development of the cells, however, is still in its infancy performance remains very poor. An analysis of the causes of this poor performance is given and possible areas for future research in the field are outlined.
    Rakhshani, A.E.
    Preparation, Characteristics and Photovoltaic Properties of Cuprous Oxide - A Review 1986 Solid State Electronics
    Vol. 29, pp. 7-17 
    article DOI  
    Abstract: The photovoltaic properties of cuprous oxide (Cu2O) are reviewed and discussed. The emphasis, however, is on reviewing the characteristics of Cu2O prepared by different techniques such as high-temperature thermal oxidation, low-temperature thermal oxidation, electro-deposition, anodic oxidation, chemical oxidation and reactive sputtering. It is shown that despite the economic prospects of efficient cells based on Cu2O, little is known about the photovoltaic properties of this material when it is fabricated by low-temperature techniques. The areas in which further research is needed because of the lack of information in the literature are pointed out.
    Rakhshani, A.E.
    Thermostimulated impurity conduction in characterization of electrodeposited Cu2O films 1991 Journal of Applied Physics
    Vol. 69, pp. 2290-2295 
    article DOI  
    Abstract: Electrodeposited films of cuprous oxide show high resistivities in the range of 109–1012 Ω cm. The p‐type conductivity, its temperature dependence, and its thermostimulated characteristics can be explained by assuming that a pair of deep levels (acceptor and donor type) control the electrical properties of these films. A novel thermostimulated conductivity model is introduced to include the effect of impurity conduction. Impurity conduction through the acceptor‐type level is the dominant transport mechanism at temperatures below approximately 200 K. The experimental results on thermostimulated conductivity measurements reveal the effect of Poole–Frenkel lowering of the ionization energy of the acceptor‐type deep level. For a typical sample the zero‐field ionization energy of this level is 0.792 eV. Having a concentration of 5×1013 cm−3 and a hole capture cross section of 3.12×10−9 cm2, this level is compensated with a donor‐type level of unknown ionization energy having a concentration of 1.89×1013 cm−3. Impurity conduction in this sample shows an activation energy of 0.03 eV before and 0.08 eV after a sample is illuminated at 77 K. From the measurement of the Poole–Frenkel constant the electron affinity of the film is obtained to be 2.9 eV.
    Rakhshani, A.E.
    The role of space-charge-limited-current conduction in evaluation of the electrical properties of thin Cu2O films 1991 Journal of Applied Physics
    Vol. 69, pp. 2365-2369 
    article DOI  
    Abstract: Space-charge-limited-current conduction is the dominant charge transport mechanism in electrodeposited films of cuprous oxide; the measurement of current‐voltage characteristic and temperature dependence of conductivity, while charge transport is space‐charge limited, is used to evaluate the electrical parameters of the films. From these measurements and the measurement of the material band gap and dielectric constant, the energy‐band diagram of Cu2O films has been determined for the first time. An optoelectronic band gap of 2.0 eV and a dielectric constant of 8.8 is measured for these films. The hole mobility in a sample with a resistivity of 1.1×1011 Ω cm is measured to be 8.7 cm2/V s. The conductivity of this sample is controlled by an acceptor‐type deep level (0.54 eV above valence band) with a concentration of 6.65×1014 cm−3 which is compensated with a donor‐type level (0.92 eV below conduction band) having a concentration of 6.64×1014 cm-3.
    Rakhshani, A.E., Makdisi, Y., and Mathew, X.
    Deep energy levels and photoelectrical properties of thin cuprous oxide films 1996 Thin Solid Films
    Vol. 288, pp. 69-75 
    article DOI  
    Abstract: Thin films of cuprous oxide have been electrodeposited on molybdenum substrates. Some preliminary photoelectrical properties of two devices with semitransparent aluminum and gold top-electrodes have been measured. The device with a gold top-electrode exhibits a weak photovoltaic effect and a space charge limited current conduction mechanism in dark. The other device which had been annealed before the deposition of the aluminum top-electrode, exhibits a three-fold increase in resistivity and a marked difference in its temperature dependence of conductivity. From the temperature dependence of conductivity, two activation energies of 0.09 and 0.87 eV could be measured compared to 0.11 and 0.26 eV for the device with a gold electrode.
    Photoinduced current transient spectroscopy with a novel approach to the post-capture data analysis (additive double gate analysis) has been used in detection and the measurements of the parameters of several deep energy levels. These levels have activation energies in the range of 0.12 to 0.63 eV and capture cross-sections in the range of 10−22 to 10−12 cm2. Using the role of the sample bias polarity on the identification of the type of the traps, one electron trap (surface state) and one hole trap (bulk state) could be identified among the five detected deep levels.
    Ralph, H.I.
    Electric field effects on the direct optical transition to the $1s$ exciton in cuprous oxide 1969 Solid State Communications
    Vol. 7, pp. 1129-1130 
    article DOI  
    Abstract: It is shown that the results of recent measurements made by Brahms and Cardona on the electro optical absorption due to the 1s exciton in the yellow series of cuprous oxide are in accordance with Elliott's theory of optical absorption.
    Ramsier, R.D., Mallik, R.R., and Henriksen, P.N.
    Investigation of thermally grown copper oxides with inelastic electron tunneling spectroscopy 1989 Journal of Applied Physics
    Vol. 66, pp. 4539-4541 
    article DOI  
    Abstract: Low energy inelastic electron tunneling spectra are presented for thermally formed oxides on copper films. Thinner oxide tunnel barriers are observed to contain interfacial gradients as evidenced by spectral intensity asymmetries between forward and reverse bias, whereas thicker oxides appear to be more uniform in composition. Spectral results are in good qualitative agreement with reported studies of bulk cuprous oxides, and the semiconducting nature of the oxide layers is reflected in a negative temperature coefficient of resistivity of the tunnel junctions.
    Ray, S.C.
    Preparation of copper oxide thin film by the sol-gel-like dip technique and study of their structural and optical properties 2001 Solar Energy Materials and Solar Cells
    Vol. 68(3-4), pp. 307-312 
    article DOI  
    Abstract: Copper oxide films are prepared using a methanolic solution of cupric chloride (CuCl2���2H2O) by the sol-gel-like dip technique at different baking temperatures. XRD study confirms that the films are of Cu2O phase when prepared at a baking temperature of 360�C and CuO phase when prepared at 400-500�C baking temperature. The optical direct band gap energies for Cu2O and CuO films calculated from optical absorption measurements are 2.10 and 1.90�eV, respectively, which are quite comparable with the reported values.
    Raynaud, G.M. and Rapp, R.A.
    In situ observation of whiskers, pyramids and pits during the high-temperature oxidation of metals 1984 Oxidation of Metals
    Vol. 21(1), pp. 89-102 
    article DOI  
    Abstract: A hot-stage, environmental scanning electron microscope has been used to observe the in situ development of oxide whiskers, pyramids, and pits in the oxidation of copper and nickel at elevated temperatures. The effects of oxidation temperature, metal deformation, and the presence of water vapor on these irregular oxidation features were studied. In each case, the feature results from the presence of a central screw dislocation which provides ledges for the extension of the oxide lattice, but the specific geometries are decided by factors such as surface diffusion along the dislocation core, the rate of the molecular dissociation step, and the balance of surface energy and dislocation line tension forces.
    Reddy, A.S., Rao, G.V., Uthanna, S., and Reddy, P.S.
    Influence of substrate bias voltage on the properties of magnetron sputtered Cu2O films 2005 Physica B
    Vol. 370, pp. 29-34 
    article DOI  
    Reddy, A.S., Uthanna, S., and Reddy, P.S.
    Properties of dc magnetron sputtered Cu2O films prepared at different sputtering pressures 2007 Applied Surface Science
    Vol. 253, pp. 5287-5292 
    article DOI  
    Abstract: The sputtering pressures maintained during the deposition of Cu2O films, by dc reactive magnetron sputtering, influence the structural, electrical and optical properties. The crystalline orientation mainly depends on the sputtering pressure. The films deposited at a sputtering pressure of 4 Pa showed single-phase Cu2O films along (1 1 1) direction. The electrical resistivity of the films increased from 1.1 × 101 Ω cm to 3.2 × 103 Ω cm. The transmittance of the films increased from 69% to 88% with the increase of sputtering pressure from 2.5 Pa to 8 Pa.
    Reichel, F., Jeurgens, L.P.H., and Mittemeijer, E.J.
    The thermodynamic stability of amorphous oxide overgrowths on metals 2008 Acta Materialia
    Vol. 56(3), pp. 659-674 
    article DOI  
    Abstract: On a thermodynamic foundation, in particular for interface energetics, the initial oxide overgrowth on a bare metal surface can be predicted to be either amorphous or (semi-)coherent crystalline, as function of the oxidation temperature and substrate orientation. Model calculations were performed for a range of metal/oxide systems (oxidation of Al, Ni, Cu, Cr, Fe, Mg, Zr and Ti) on the basis of the sum of the surface, interfacial and bulk energy differences between the competing amorphous and crystalline oxide overgrowths on the same metal substrate. It follows that an amorphous state for the initial oxide overgrowth can be thermodynamically (instead of kinetically) preferred as long as the higher bulk Gibbs energy of the amorphous oxide overgrowth is overcompensated for by its low sum of surface and interface energies. The dominating factors, which thermodynamically favour the formation of an amorphous oxide overgrowth, are exposed and discussed.
    Reimann, K.
    Thermalization of excitons in Cu2O 1988 Journal of Luminescence
    Vol. 40-41, pp. 475-476 
    article DOI  
    Abstract: The thermalization of excitons in Cu2O is investigated by monitoring the lineshape of the phonon-assisted luminescence for different crystal temperatures and excitation conditions. At low temperatures (less than 10 K) the excitons reach thermal equilibrium. At higher temperatures this is the case only for nonresonant excitation, whereas for resonant excitation the exciton distribution is nonthermal. These lineshapes can be explained quantitatively by a theory which takes into account the coupling of excitons to acoustic and optical phonons.
    Reydellet, J., Balkanski, M., and Trivich, D.
    Light Scattering and Infrared Absorption in Cuprous Oxide 1972 Physica Status Solidi (b)
    Vol. 52, pp. 175-185 
    article DOI  
    Abstract: A great number of bands have been observed by light scattering and infrared absorption in Cu2O crystals corresponding to transitions most of which are normally forbidden in the perfect crystal. An analysis of the symmetry properties of the lattice modes in the presence of defects is given. In particular the role of each symmetry site for the defects is investigated and the observed modes interpreted as being due to actived band modes and localized modes. Double phonon processes are observed as well as the normally allowed optical transtions for the perfect crystal.
    Rhodin Jr., T.N.
    Low Temperature Oxidation of Copper. I. Physical Mechanism1a 1950 Journal of the American Chemical Society
    Vol. 72(11), pp. 5102-5106 
    article DOI  
    Rhodin Jr., T.N.
    Low Temperature Oxidation of Copper. II. Reaction Rate Anisotropy 1951 Journal of the American Chemical Society
    Vol. 73(7), pp. 3143-3146 
    article DOI  
    Richardson, T.J., Slack, J.L., and Rubin, M.D.
    Electrochromism in copper oxide thin films 2001 Electrochimica Acta
    Vol. 46(13-14), pp. 2281-2284 
    article DOI  
    Abstract: Transparent thin films of copper(I) oxide prepared on conductive SnO2/F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85 to 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20-100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE=60 cm2/C), but covered a smaller transmittance range (60-44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.
    von Richthofen, A., Domnick, R., and Cremer, R.
    Preparation of cuprite (Cu2O), paramelaconite (Cu$_3^2+$Cu$_2^1+$O$_4$) and tenorite (CuO) with magnetron sputtering ion plating: characterization by EPMA, XRD, HEED and SEM 1997 Fresenius' Journal of Analytical Chemistry
    Vol. 358(1), pp. 312-315 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp; Cu-O layers were deposited on Si-&lt;100&gt; wafers at 90° C by means of reactive magnetron sputtering ion plating (R-MSIP). A Cu-target was sputtered in rf-mode by an oxygen/argon plasma, and the influence of the oxygen partial pressure on composition, structure, texture and morphology of the Cu-O layers was investigated. The analysis with EPMA, XRD, HEED and SEM yielded the following results: with an appropriate setting of the oxygen partial pressure, the oxygen content of the films could be controlled between 0 and 50 at-%. XRD bulk structure analysis shows changes in the crystal structure of the films with increasing oxygen content from the fcc structure of Cu, followed by the sc structure of Cu2O (cuprite), the tetragonal structure of Cu3 2+Cu2 1+O4 (paramelaconite) to the monoclinic structure of CuO (tenorite). As revealed by HEED, the structure of the near-surface region of the latter two is the same as that of the bulk, whereas in the case of the films with fcc bulk structure, due to oxidation by air, the surface has the sc structure of Cu2O, and in the case of the film with the sc structure, a monoclinic surface structure of CuO is observed. SEM analyses detected a disordered columnar growth of all Cu-O films.
    Riess, I.
    Measurement of ionic conductivity in semiconductors and metals 1991 Solid State Ionics
    Vol. 44(3-4), pp. 199-205 
    article DOI  
    Abstract: The possible application of a solid state, electrochemical method for the determination of the ionic conductivity in semiconductors and metals is analyzed. It is shown that the poor ionic conductivity of many semiconductors and metals poses stringent constraints on the experimental set-up. However, when these constraints are fulfilled the method allows for an accurate measurement of the ionic conductivity, under controlled sample composition, by two and four electrodes arrangements.
    Riess, I.
    Recent investigations into the properties of mixed ionic electronic conductors 1992 Materials Science and Engineering B
    Vol. 12(4), pp. 351-356 
    article DOI  
    Abstract: The ionic conductivity in mixed ionic electronic conductors (MIECs) is usually determined by a polarization technique analogous to the Hebb-Wagner polarization method used for determining the electronic (electron/hole) conductivity. However, this technique has some experimental difficulties which may render the results useless. These difficulties are discussed and examples are presented. A new method is presented, which is denoted as the "zero driving force" technique. In this method the electronic current is eliminated by short circuiting, thus eliminating the driving force acting on the electrons/holes. This new technique does not suffer from the drawbacks of the polarization method. It is shown that MIEC probes can be used to transfer and information. Two voltemeters connected to MIEC probes applied to an MIEC sample can be used to measure and . This measurement is simultaneous and refers to the same two contact points. However, reversible probes cannot generally be tolerated on MIECs in the one-dimensional configuration.
    Riess, I.
    Mixed ionic--electronic conductors--material properties and applications 2003 Solid State Ionics
    Vol. 157, pp. 1-17 
    article DOI  
    Abstract: Mixed ionic–electronic conductors (MIECs) are examined first with respect to their possible applications and then with respect to their properties. The emphasis is on electrochemical cells in which a MIEC serves either as an electrode or it replaces the solid electrolyte (SE). The dependence of the I–V relations on point defects nature, concentrations and local neutrality is discussed. The question whether it is possible to introduce significant changes in the defect concentrations by doping is examined and shown to have, in many cases, a negative answer. In MIECs the partial electronic (electron/hole) and ionic currents have to be treated separately and so also the corresponding partial conductivities. Methods for determining the partial conductivities are discussed.
    Riess, I.
    $I$---$V$ relations in semiconductors with ionic motion 2006 Journal of Electroceramics
    Vol. 17(2), pp. 247-253 
    article DOI  
    Abstract: Semiconductors with mobile donors and acceptors are mixed-ionic-electronic-conductors, MIECs, which exhibit peculiar electronic (electron/hole), I e , current-voltage relations. This is a result of the redistribution of the ions under the applied electrical potential. MIECs are usually ionic materials which exhibit relative low electron/hole mobilities as compared to the materials used in the semiconductor industry. However, thin layers of MIECs exhibit a low resistance and fast response and become of increasing interest.
    The I e −V relations are discussed for a few typical examples. It is shown that they depend on the energy band gap as when it is large, the semiconductor is either p-type or n-type. The I e −V relations depend also on the nature of the electrodes, whether blocking for ion exchange or not. Experimental results for Cu2O are presented and analyzed using one of the models discussed.
    Righi, A.
    Risposta alle osservation del sig. Hallwachs 1890 Il Nuovo Cimento
    Vol. 28(1), pp. 62-63 
    article DOI  
    Ristova, M., Neskovska, R., and Mirceski, V.
    Chemically deposited electrochromic cuprous oxide films for solar light modulation 2007 Solar Energy Materials and Solar Cells
    Vol. 91(14), pp. 1361-1365 
    article DOI  
    Abstract: Thin cuprous oxide electrochromic films on the transparent conductive electrodes were prepared by chemical electroless method. The films cycled in K+-based electrolyte revealed typical red-ox peaks with higher intensity compared to those in the Li+ and the Na+-based electrolytes. The durability of the cuprous oxide due to cycling into LiClO4 was about 60 cycles. The thermal treatment of the films invoked decrease in red-ox peak intensity, and thus deterioration in the electrochromic properties. The response time of the coloration and bleaching to an abrupt voltage change from -4.5 to +4.5�V and reverse was found to be in the range of about 10�s. The maximum light intensity modulation ability of the films, as the AM1.5 spectrum is taken for an input, was calculated to be about 65%.
    Roberts, H.S. and Smyth, F.H.
    THE SYSTEM COPPER: CUPRIC OXIDE: OXYGEN. 1921 Journal of the American Chemical Society
    Vol. 43(5), pp. 1061-1079 
    article DOI  
    Roberts, E.F.I. and Rastall, P.
    The optical constants of natural and artificial cuprite by an ellipsometric method 1978 Mineralogical Magazine
    Vol. 42, pp. 505-508 
    article URL 
    Robertson, J.
    Electronic structure and X--ray near-edge core spectra of Cu2O 1983 Physical Review B
    Vol. 28, pp. 3378-3385 
    article DOI  
    Abstract: A new tight-binding band structure of Cu2O is presented from a fit to the valence-band density of states and low-energy band gaps. The depths of core excitons and the near-edge structure of the O K edge are calculated using the Z+1 approximation to the core-hole potential and the local density of states of the excited atom. The chemical trends of its impurity levels are predicted and partial densities of states are found.
    Rodney, P.J.
    The Photophysics of Ionic Semiconductors at Low Temperatures: Silver Bromide, Silver Iodide and Cuprous Oxide 1998 School: University of Rochester  phdthesis URL 
    Rönnow, D., Lindström, T., Isidorsson, J., and Ribbing, C.G.
    Surface roughness of oxidised copper films studied by atomic force microscopy and spectroscopic light scattering 1998 Thin Solid Films
    Vol. 325(1-2), pp. 92-98 
    article DOI  
    Abstract: The interface roughness of Cu2O films produced by thermal oxidation of Cu was studied by spectroscopic elastic light scattering and atomic force microscopy. No correlation could be found between the roughness of the two interfaces, although the amplitude and the length scale of the roughness changed in the same way with film thickness for both interfaces. Both interfaces were found to have a fractal dimension of two. A first order perturbation theory was used to analyse the light scattering data; theory and experiment are in good agreement within the limits of the theory.
    Rönnquist, A. and Fischmeister, H.
    The oxidation of copper -- A review of published data 1960--1961 Journal of the Institute of Metals
    Vol. 89, pp. 65-76 
    Rosenstock, Z. and Riess, I.
    Preparation of oxide thin films by controlled diffusion of oxygen atoms 2000 Solid State Ionics
    Vol. 136-137, pp. 921-926 
    article DOI  
    Abstract: A new method for preparing thin oxide films is described. It makes use of slow diffusion of oxygen through a permeable layer, towards the metal to be oxidized. We have used this method to oxidize copper. The permeable layer is a dense silver film. The formation of the oxide was followed in situ in an attempt to measure the resistance of the cell.
    Rosenstock, Z., Feldman, I., and Riess, I.
    Solid state devices based on thin films of Cu2O show a new type of $I$--$V$ relations 2004 Solid State Ionics
    Vol. 175, pp. 375-378 
    article DOI  
    Abstract: Solid state devices based on Cu2O are found to exhibit different current–voltage (I–V) relations. Though these devices have been known for almost 80 years they are still not fully understood. The standard interpretation of these I–V relations is by assuming Schottky barriers to exist between a metal electrode and the oxide. We here report on a new form of I–V relations that we have measured for devices based on thin films of Cu2O. Their interpretation calls upon mixed ionic electronic conduction in the oxide. The ionic conductivity, though low, is sufficient to allow a redistribution of the native acceptors on the time scale of the measurements, thereby affecting the electronic current carried by holes. Any contribution to the I–V relations from Schottky barriers is not significant.
    Rosenstock, Z., Feldman, I., Gil, Y., and Riess, I.
    Semi-Conductors with Mobile Ions Show a New Type of I--V Relations 2005 Journal of Electroceramics
    Vol. 14, pp. 205-212 
    article DOI  
    Abstract: Semi-conductors with mobile acceptors or donors show a new type of I-V relations. This paper presents experimental results for solid state devices based on copper oxide, found to be Cu2O, which exhibit these I-V relations. The cells examined are Cu| Cu2O| In and Cu| Cu2O| Ag and similar ones tested at room temperature. The measured I-V relations are different from those reported for the same type of cells in the past, which were explained to be fixed by a Schottky barrier Cu| Cu2O. We find that the I-V relations relax over a long time which we claim is due to ion redistribution. The new I-V relations can then be explained by assuming that Cu2O is a mixed-ionic-electronic-conductor and adopting a theory developed by us in the past and modified to be applicable to the relevant defect model here. In this case the contribution of Schottky barriers is insignificant.
    Roslyak, O. and Birman, J.L.
    Hybridized quadrupole-dipole exciton effects in a Cu2O-organic heterostructure 2007 Physical Review B
    Vol. 75(24), pp. 245309 
    article DOI  
    Abstract: In the present work, we discuss resonant hybridization of the 1S quadrupole Wannier-Mott exciton (WE) in a Cu2O quantum well with the Frenkel dipole exciton in an adjacent layer of organic DCM2:CA:PA. The coupling between excitons is due to interaction between the gradient of electric field induced by the DCM2 Frenkel exciton (FE) and the quadrupole moment of the 1S transition in the cuprous oxide. The specific choice of the organic allows us to use the mechanism of “solid state solvation” [C. Madigan and V. Bulovic, Phys. Rev. Lett. 91, 247403 (2003)] to dynamically tune the WE and FE into resonance for ≈3.3ns (comparable with the big lifetime of the WE) of the “slow” phase of the solvation. The quadrupole-dipole hybrid utilizes the big oscillator strength of the FE, along with the big lifetime of the quadrupole exciton, unlike dipole-dipole hybrid exciton which utilizes the big oscillator strength of the FE and big radius of the dipole allowed WE. Due to the strong spatial dispersion and big mass of the quadrupole WE, the hybridization is not masked by the kinetic energy or the radiative broadening. The lower branch of the hybrid dispersion exhibits a pronounced minimum and may be used in applications. Also, we investigate and report noticeable change in the coupling due to an induced “Stark effect” from the strong local electric field of the FE. We investigated the fine energy structure of the quantum well confined ortho and para excitons in cuprous oxide.
    Roslyak, O. and Birman, J.L.
    Theory of enhanced dynamical photo-thermal bi-stability effects in cuprous oxide/organic hybrid heterostructure 2007 Solid State Communications
    Vol. 143, pp. 487-492 
    article DOI  
    Abstract: We theoretically demonstrate the formation of multiple bi-stability regions in the temperature pattern on the interface between a cuprous oxide quantum well and DCM2:CA:PS organic compound. The Frenkel molecular exciton of the DCM2 is brought into resonance with the 1S quadrupole Wannier Mott exciton in the cuprous oxide by “solvatochromism” with CA. The resulting hybrid is thermalized with the surrounding helium bath. This leads to strongly non-linear temperature dependence of the laser field detuning from the quadrupole exciton energy band which is associated with the temperature-induced red shift of the Wannier exciton energy. A numerical up- and down-scan for the detuning reveals hysteresis-like temperature distribution. The obtained multiple bi-stability regions are at least three orders of magnitude bigger (meV) than the experimentally observed bi-stability in bulk cuprous oxide (μeV ). The effective absorption curve exhibits highly asymmetrical behavior for the Frenkel-like (above the 1S energy) and Wannier-like (below the 1S energy) branches of the hybrid.
    Roy, S., Bose, S., and Sircar, S.
    Pressure dependencies of copper oxidation for low- and high-temperature parabolic laws 1991 Oxidation of Metals
    Vol. 35(1), pp. 1-18 
    article DOI  
    Abstract: Studies of the oxidation kinetics of copper have been conducted in the thin-film range at temperatures of 383–398 K and in the oxygen pressure range of 0.278–21.27 kPa; whereas in the thick-film regime at 1123 K, studies have been conducted in the oxygen pressure range of 2.53–21.27 kPa. Furthermore, the effect of continuously impressed direct current with oxygen pressure variation in Wagner's parabolic range has been studied also in order to have a better understanding of the effective charge on the migrating species. In the low-temperature range, the rate constant, kP ∝ , suggesting that the migration of neutral vacancies in the growing film predominates. At high temperature, 1123 K, in the Wagnerian regime, the observed approximate pressure dependencies of the parabolic rate constants are the following:
    Roy, S.K., Ananth, V., and Bose, S.K.
    Oxidation behavior of copper at high temperatures under two different modes of direct-current applications 1995 Oxidation of Metals
    Vol. 43(3), pp. 185-215 
    article DOI  
    Abstract: Oxidation kinetics of copper in the temperature range of 973–1173 K atPO2=21.27 kPa exhibit enhancement and deceleration in the rates with changing polarity compared to normal oxidation under interrupted mode of directcurrent application. These conditions are achieved by connecting the oxidizing copper covered with an initially formed thin oxide film to the positive and negative terminal of a dc source, respectively. However, the influence of direction of the current is found to be opposite under uninterrupted mode of impressed current flow in the same temperature range. The effect of short-circuiting the metal to the outer oxide/air interface on the reaction kinetics is also reported. The rate of oxide-scale growth under normal condition, and two different modes of current applications as well as with shorting circuitry attachment conform to the parabolic growth law. The results pertaining to the two different modes of impressed current have been discussed considering both the phenomena of electrolysis of the oxide electrolyte and the polarization at the two phase boundaries. The enhancement and the reduction in rates under uninterrupted impressed current conditions are explained on the basis of increased and decreased average defect concentrations, respectively, within the oxide layer. The acceleration and deceleration in the rates under interrupted mode of current flow have been explained in the light of sustenance of a steeper and flatter electrochemical-potential gradient of defects, respectively, across the growing-oxide layer. The possible different responses of the metal/oxide and oxide/air interfaces to the impressed current brought into play by two different modes of current application, have enabled to display a better insight on the mechanistic aspects of scale growth under the influence of an externally applied current.
    Roy, S.K., Mitra, S.K., and Bose, S.K.
    Influence of an Externally-Applied Static Charge on the Oxidation Kinetics of Copper 1998 Oxidation of Metals
    Vol. 49(3), pp. 261-295 
    article DOI  
    Abstract: The kinetics of copper oxidation under theinfluence of an externally-supplied static charge ofeither kind at one of the reaction interfaces of agrowing oxide film on its subsequent thickening weredetermined in the temperature range of 523-1173 K andoxygen-pressure range of 5.06-50.66 kPa. The kineticsconformed to the parabolic rate law under all conditionsof experimentation. In the temperature range of 523-723 K, charge supply of either kind ateither of the oxide interfaces, reduced the ratescompared to normal oxidation. The reduction in rates ismore pronounced with (-)ve charge supply. In thistemperature range, Mott's in situ electrical-potentialgradient across the oxide film is identified as thepredominant driving force for migration of copper ionsduring the subsequent film-thickening process. On the other hand, in the temperature range of 873-973K, a charge supply of either kind enhanced the ratescompared to normal oxidation, where Wagner'selectrochemical-potential gradient acts as the maindriving force for ion diffusion. However, at 1073 K and1173 K, the rates were found to decrease slightlycompared to normal oxidation. The oxygen-pressuredependencies of rate constants at 623 K exhibitedrelations of the type kP ?PO21/4 for normal and kp ?PO21/8 (approximately) for oxidation witheither (+)ve or (-)ve charge supply at the oxide/oxygeninterface. However, at 873 K the oxygen-pressuredependencies of rate constants conform to kP ?PO21/6 for normal as well as for oxidationwith either (+)ve or (-)ve charge supply at theoxide/oxygen interface. The estimated activationenergies are 54 kJ/mol and 160 kJ/mol in Mott's and Wagner's parabolic ranges,respectively. It is established that migration of Cu+ions through the growing film is the rate-limiting stepunder all conditions of experimentation. This study has clearly demonstrated that changes inoxidation rates can be brought about by disturbing theinterfacial defect equilibria with anexternally-supplied static charge when no net currentflows through the oxide film. The estimated self-diffusivityvalues of Cu+ ions in the growingCu2O at 873 K are also reported.
    Ruiz, E., Alvarez, S., Alemany, P., and Evarestov, R.A.
    Electronic structure and properties of Cu2O 1997 Physical Review B
    Vol. 56(12), pp. 7189-7196 
    article DOI  
    Abstract: The structural and electronic properties of Cu2O have been investigated using the periodic Hartree-Fock method and a posteriori density-functional corrections. The lattice parameter, bulk modulus, and elastic constants have been calculated. The electronic structure of and bonding in Cu2O are analyzed and compared with x-ray photoelectron spectroscopy spectra, showing a good agreement for the valence-band states. To check the quality of the calculated electron density, static structure factors and Compton profiles have been calculated, showing a good agreement with the available experimental data. The effective electron and hole masses have been evaluated for Cu2O at the center of the Brillouin zone. The calculated interaction energy between the two interpenetrated frameworks in the cuprite structure is estimated to be around -6.0 kcal/mol per Cu2O formula. The bonding between the two independent frameworks has been analyzed using a bimolecular model and the results indicate an important role of d10-d10 type interactions between copper atoms.
    Rustagi, K.C., Pradere, F., and Mysyrowicz, A.
    Two-Photon Absorption in Cu2O 1973 Physical Review B
    Vol. 8(6), pp. 2721-2732 
    article DOI  
    Samarasekara, P., Arachchi, M., Abeydeera, A., Fernando, C., Disanayake, A., and Rajapakse, R.
    Photocurrent enhancement of d.c. sputtered copper oxide thin films 2005 Bulletin of Materials Science
    Vol. 28(5), pp. 483-486 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;Copper oxide (CuO) thin films with photocurrent as high as 25 μA/cm2 were deposited on conductive glass substrates using d.c. reactive sputtering. This was the highest reported photocurrent for sputteredp- type copper oxide measured in the electrolyte KI. The photocurrent drastically increased up to 25 (μA/cm2 as the sputtering pressure and the substrate temperature were increased up to 8.5 mbar and 192°C, respectively. All the synthesized films contained single phase of CuO in this range of pressure and substrate temperature. Variation of the photocurrent, photovoltage, structure and absorbance with deposition conditions were studied in detail.
    Samuelson, A.G.
    Visualizing orbitals and bonds 1999 Current Science
    Vol. 77, pp. 1131-1132 
    article URL 
    Sanson, A., Rocca, F., Dalba, G., Fornasini, P., Grisenti, R., Dapiaggi, M., and Artioli, G.
    Negative thermal expansion and local dynamics in Cu2O and Ag2O 2006 Physical Review B
    Vol. 73(21), pp. 214305 
    article DOI  
    Santra, K., Sarkar, C.K., Mukherjee, M.K., and Ghosh, B.
    Copper oxide thin films grown by plasma evaporation method 1992 Thin Solid Films
    Vol. 213(2), pp. 226-229 
    article DOI  
    Abstract: Copper oxide thin films have been grown by the plasma evaporation method. The thin films were deposited on the substrates by evaporating metallic copper through a plasma discharge in the presence of a constant oxygen pressure. The X-ray diffraction patterns of the films were investigated before and after the films had been annealed in a nitrogen atmosphere. By X-ray diffraction, the cuprous oxide (Cu2O) phase is identified before annealing and it changes to cupric oxide (CuO) after annealing. The optical absorption of the films was also measured. The results were analysed in detail and the band gap energies for Cu2O) and CuO are 2.1 eV and 1.85 eV respectively. The types of the film before annealing and after annealing are also measured using thermo-e.m.f. probes and the results indicate that the films are p type. Thin films prepared in the absence of a reactive gas and plasma were also deposited on glass substrates. The X-ray analysis of these films shows the presence of metallic copper only.
    Santucci, S. and Picozzi, P.
    Oxidation of very thin copper films investigated by optical transmittance 1984 Thin Solid Films
    Vol. 113(3), pp. 243-250 
    article DOI  
    Abstract: Very thin copper films were prepared by thermal evaporation onto quartz slides. The time evolution of the optical transmittance of such coatings, resulting from the oxidation process, was recorded for wavelengths of 0.25-2.5 [mu]m. Electron microscopy studies indicated that the films consisted of Cu2O and copper particles surrounded by air. We calculated the dielectric constant of this system using an extended Bruggeman effective medium theory taking into account various possible aggregation models of the particles. The experimental data agree with a model consisting of Cu2O, copper and air spheres. A comparison between the calculated and measured transmittances allows the mass increase of the samples during the oxidation process to be estimated.
    Scanlon, D.O., Morgan, B.J., and Watson, G.W.
    Modeling the polaronic nature of $p$-type defects in Cu2O: The failure of GGA and GGA$+U$ 2009 The Journal of Chemical Physics
    Vol. 131(12), pp. 124703 
    article DOI  
    Abstract: The exact nature of the hole traps reported deep in the band gap of Cu2O has been a topic of vigorous debate, with copper vacancies and oxygen interstitials both having been proposed as the relevant defects. In this article, the electronic structure of acceptor-forming defects in Cu2O, namely, copper vacancies and oxygen interstitials, is investigated using generalized gradient approximation (GGA) and GGA corrected for on-site Coulombic interactions (GGA+U). GGA produces notionally semimetallic defect complexes, which is not consistent with the experimentally known polaronic nature of conduction in Cu2O. GGA+U also predicts a semimetallic defect complex for the “simple” copper vacancy but predicts the “split” vacancy and both oxygen interstitials are characterized by localized polarons, with distinct single particle levels found in the band gap. For both methods, however, the positions of calculated transition levels are inconsistent with experimental ionization levels. Hence neither GGA nor GGA+U are successful in modeling p-type defects in Cu2O.
    Scanlon, D.O., Morgan, B.J., Watson, G.W., and Walsh, A.
    Acceptor Levels in $p$-Type Cu2O: Rationalizing Theory and Experiment 2009 Physical Review Letters
    Vol. 103(9), pp. 096405 
    article DOI  
    Schick, J.D. and Trivich, D.
    Photokinetics in Single-Crystal Cuprous Oxide 1971 Chemical Physics Letters
    Vol. 10, pp. 465-467 
    article DOI  
    Abstract: The minority carrier lifetime of cuprous oxide is measured on single-crystal samples equilibrated at various oxygen pressures, and its dependence on oxygen partial pressure is shown. This dependence supports the conclusion that copper atom vacancies give rise to recombination centers.
    Schick, J.D. and Trivich, D.
    Electron Trapping in Single Crystal Cuprous Oxide 1972 Journal of the Electrochemical Society
    Vol. 119, pp. 376-380 
    article DOI  
    Abstract: Samples of Cu2O after illumination at low temperatures possess a higher electrical conductance than the same samples without preillumination. The excess conductance is removed by heating above 100°C. The possibility that this "photomemory" effect is due to electron trapping was investigated by methods analogous to thermally stimulated conductivity. When the preilluminated samples are heated at a constant rate with time, = dT/dt = constant, the plots of excess conductance vs. temperature are characterized by two maxima lying at about 25° and 100°C. Under different heating rates, the temperatures of the maxima, Tm, are shifted according to the function In (Tm2/) = Et/kTm + constant. The values of Et obtained are interpreted as indicating traps lying 1.03 and 1.34 eV below the conduction band, with a precision of ±15%.
    Schmidt-Whitley, R.D., Martinez-Clemente, M., and Revcolevschi, A.
    Growth and Microstructural Control of Single Crystal Cuprous Oxide Cu2O 1974 Journal of Crystal Growth
    Vol. 23, pp. 113-120 
    article DOI  
    Abstract: Large single crystals of cuprous oxide, Cu2O, have been grown by a floating zone technique using an arc-image furnace. The microstructure of the polycrystalline starting material obtained by oxidation of copper and of the single crystals grown from the melt have been investigated in detail, as well as the influence of atmosphere, solidification rate and impurity concentration. The precipitate structure inherent to the conditions of crystal growth was extremely complex, consisting of various forms of cupric oxide inclusions and aggregates of gas and cupric oxide. The microstructural changes accompanying high-temperature annealing within the cuprous oxide stability field are described. A procedure for crystal growth and treatment which minimizes the amount of defects is developed.
    Schramm, L., Behr, G., Löser, W., and Wetzig, K.
    Thermodynamic Reassessment of the Cu2O Phase Diagram 2005 Journal of Phase Equilibria and Diffusion
    Vol. 26, pp. 605-612 
    article DOI  
    Abstract: Parts of the copper-oxygen equilibrium phase diagram were reassessed using the calculation of phase diagram technique (CALPHAD). The model parameters were optimized to yield the best fit between calculated and experimentally determined phase equilibria at elevated oxygen pressures up to 11 MPa. The Cu-O liquid phase is represented by the two-sublattice model for ionic liquids containing copper on the cation sublattice with formal valences of Cu+1, Cu+2, and Cu+3. The presence of Cu+3 ions in the liquid phase, corresponding to a formation of Cu2O3 species, was the key assumption of this model. Congruent melting of CuO at 1551 K under an oxygen pressure of ∼126.8 MPa is predicted, which is considerably below previous theoretical values.
    Schulz, K.H. and Cox, D.F.
    Photoemission and low-energy-electron-diffraction study of clean and oxygen-dosed Cu2O $(111)$ and $(100)$ surfaces 1991 Physical Review B
    Vol. 43(2), pp. 1610-1621 
    article DOI  
    Abstract: The geometric and electronic structure of clean and oxygen-dosed Cu2O single-crystal surfaces was studied with x-ray and ultraviolet photoelectron (UPS) spectroscopies and low-energy electron diffraction. The nonpolar (111) surface can be prepared in a nearly stoichiometric (1×1) form by ion bombardment and annealing in vacuum. Oxygen adsorbs molecularly on the stoichiometric (111) surface at 300 K, but adsorbs dissociatively on a defective (111) surface prepared by ion bombardment. For the polar Cu2O(100) face it was possible to prepare a reconstructed, Cu-terminated surface with a (3√2 × √2 )R45° periodicity by ion bombardment and annealing in vacuum. Preparation of an unreconstructed, (1×1), O-terminated (100) surface was possible by large (109-L) oxygen exposures. UPS investigations of the O-terminated (100) surface suggest a mixture of incorporated (i.e., lattice) oxygen and adsorbed atomic oxygen (i.e., adatoms) in the terminating layer. The annealing behavior of the Cu2O(100) surface was history dependent. Early in the sample history, bulk lattice oxygen diffused to the surface at temperatures above 800 K giving domains of (√2 × √2 )R45° periodicity associated with half a terminating layer of oxygen atoms. After repeated ion bombardment and annealing cycles, heating above 800 K gave only a Cu-terminated surface, apparently because of a depletion of bulk lattice oxygen.
    Schwab, C., Marvillet, F., Adloff, J.P., and Nikitine, S.
    Étude des séries excitoniques jaune et verte dans des cristaux de Cu2O, dopés à l'argent 1964 Journal de Physique
    Vol. 25(4), pp. 381-382 
    article DOI  
    Abstract: The absorption spectra of thin samples of silver-doped Cu2O have been studied at 4,2 °K and 77 °K. The concentration range was (0-2) mole %. A shift of both the yellow and green series towards the lower energies is observed. This shift increases with the concentration of silver. Furthermore, the linewidths increase and the continuum overlaps the line spectra with increasing concentration of impurities. The analogy of these phenomena with those found by thermal variation is remarkable, and may suggest an expansion of the crystal lattice, due to the impurities. The spin-orbit coupling separation of the valence band remains practically constant.
    Schwab, C., Hottier, C., Sieskind, M., and Nikitine, S.
    Étude quantitative du spectre d'absorption continu rouge et de la série excitonique jaune dans Cu2O dopé à l'argent 1967 Journal de Physique
    Vol. 28(1), pp. 93-97 
    article DOI  
    Abstract: Thin samples of silver-doped Cu2O have been observed at 77 °K by means of a spectrophotometric study. Detailed measurements on the red continuous spectrum and the shape of the n = 2 line of the yellow exciton series have been made. The results have been discussed and compared with the effect of temperature and with Toyozawa's theory of line-shapes of the exciton absorption bands.
    Schwab, C., Diffiné, A., Koehl, G., Carabatos, C., Sieskind, M., Calme, P., and Viel, C.
    Effets du recuit sur l'absorption optique de l'oxyde cuivreux 1968 Journal de Physique
    Vol. 29(4), pp. 317-320 
    article DOI  
    Abstract: A qualitative study of the absorption bands of cuprous oxide (Cu2 O) due to stoichiometric defects introduced by annealing in oxygen is performed at different temperatures. An estimation of the oscillator strength of one of the observed bands is given. A tentative interpretation for the observed spectrum is presented.
    Schwab, C., Goltzene, A., Meyer, B., and Nikitine, S.
    Isoelectronic Broadening of the Yellow Exciton Quadrupole Absorption Line of Cuprous Oxide 1973 Physica Status Solidi (b)
    Vol. 60, pp. 651-664 
    article DOI  
    Abstract: Experimental results of high resolution absorption measurements of the yellow exciton 1S absorption line of Cu2O single crystals,
    characterized by chemical and crystallographic analysis are reported. After correction of internal strain effects, a line broadening
    proportional to the silver content is observed, whereas the oscillator strength remains constant. Finally, these data are discussed in terms

    of diffusion and radiative recombination life times in order to estimate the possibility of observing the spin-electron resonance of these


    Sears, W.M., Fortin, E., and Webb, J.B.
    Indium tin oxide/Cu2O photovoltaic cells 1983 Thin Solid Films
    Vol. 103(1-3), pp. 303-309 
    article DOI  
    Abstract: Tin-doped (about 3%) indium oxide films 80 nm thick were deposited by magnetron sputtering and were found to form a barrier on Cu2O crystals of comparable or superior quality to that of copper. The indium tin oxide (ITO) layers have good optical transmissions (more than 85%) and high electrical conductivities (approximately 3�103 [Omega]-1 cm-1). ITO/Cu2O front cells were studied for their photovoltaic properties in view of their possible applications as solar cells. Preliminary studies give 1.0-1.25 eV for the barrier height and indicate that short-circuit current densities of several milliamp�res per square centimetre (under air mass 1 illumination) can easily be attained.
    Sears, W.M. and Fortin, E.
    Preparation and properties of Cu2O/Cu photovoltaic cells 1984 Solar Energy Materials
    Vol. 10(1), pp. 93-103 
    article DOI  
    Abstract: In view of their possible application in solar energy conversion, cuprous oxide films have been investigated. Such films have been grown on copper substrates to a thickness of a few micrometers, using both thermal and anodic oxidation techniques. The photovoltaic properties of the resulting Cu2O/Cu backwell cells are found to depend critically on the copper surface preparation, as well as on the specific conditions of oxidation. Backwall cells of the thermal variety with thicknesses down to 3 [mu]m do not quite yet approach the performance of the best Cu2O front cells, but are much simpler to grow. Serious difficulties with shorting paths in the case of thermally grown oxide and with the purity of the Cu2O in the anodic case will have to be solved before a solar cell with an oxide layer thickness in the 1.5 to 2 [mu]m range can be produced.
    Serin, N., Serin, T., and Ünal, B.
    The effect of humidity on electronic conductivity of an Au/CuO/Cu2O/Cu sandwich structure 2000 Semiconductor Science and Technology
    Vol. 15(2), pp. 112-116 
    article DOI  
    Abstract: In this study it was aimed to research the effect of humidity on the current-voltage characteristics and capacitance of an Au/CuO/Cu 2 O/Cu sandwich structure. Cuprous oxide (Cu 2 O) and cupric oxide (CuO) layers were grown on a copper sheet. In order to complete the fabrication of the Au/CuO/Cu 2 O/Cu sandwich structure a gold metal contact was then applied on the cupric oxide layer under the pressure of 1 × 10 -6 Torr. The current-voltage characteristics and effective capacitance of the sandwich structure were measured in various humidity ranges at a temperature 20 °C. It was observed that the electronic conduction and capacitance of the Au/CuO/Cu 2 O/Cu structure were strongly dependent on humidity. The effect of humidity in Au/CuO/Cu 2 O/Cu was discussed by means of the electric dipole moment of water.
    Serin, N. and Serin, T.
    The photocapacitance property of Cu/Cu2O/Au sandwich structures 2002 Semiconductor Science and Technology
    Vol. 17(11), pp. 1162-1167 
    article DOI  
    Abstract: We have carried out investigations into the photocapacitance property of domestically fabricated
    Cu/Cu 2 O/Au sandwich structures. For the fabrication, p-type cuprous oxide (Cu 2 O) was grown on a
    copper sheet, and a transparent gold metal contact was applied on the cuprous oxide layer under a
    pressure of 1 × 10 −6 Torr. The capacitance characteristics versus light intensity for different
    wavelengths in the visible region and the current–voltage characteristics of the sandwich structure
    were measured at a temperature of 15 °C. It was observed that the capacitance of the Cu/Cu 2 O/Au
    structure was significantly dependent on both wavelength and intensity of the light. The
    photocapacitance property of Cu/Cu 2 O/Au is discussed in terms of the effect of light on the
    interface states filled by charges and the change occurring in the imaginary part of the dielectric
    constant of the cuprous oxide created due to interface states.
    Seyama, M., Takamasu, T., Imanaka, Y., Yamaguchi, H., Masumi, T., and Kido, G.
    Magneto-Optical Absorption Spectra of Cu2O in an Image Map with Fine Structures at Higher Fields up to $25T$ 2003 Journal of the Physical Society of Japan
    Vol. 72, pp. 437-442 
    article DOI  
    Abstract: We have intensively studied the optical absorption spectra of Cu2O at 4.2 K and 1.5 K in an extended range of magnetic fields up to 25 T as image maps. Quasi-continuous data of the magnetic field dependence of the absorption peaks and their interaction properties reveal that the magnetic-field-driven mixing of the energy levels occurs intensively even in the lower range of magnetic fields.
    Shen, Z.-X., List, R.S., Dessau, D.S., Parmigiani, F., Arko, A.J., Bartlett, R., Wells, B.O., Lindau, I., and Spicer, W.E.
    Photoemission study of CuO and Cu2O single crystals 1990 Physical Review B
    Vol. 42(13), pp. 8081-8085 
    article DOI  
    Abstract: We present results of resonant-photoemission and high-resolution x-ray-photoemission-spectroscopy (XPS) studies on single-crystalline CuO, which confirms most of the earlier data obtained from polycrystalline samples. However, some minor differences with earlier results were also observed, which are concentrated on a mainly oxygen-related feature. The important first ionization state is much better resolved in our high-resolution XPS data, and is found to have both copper and oxygen orbital character. This is consistent (though not a proof) with the theoretical prediction that the first ionization state is a 1A1g singlet with holes on both oxygen and copper sites. The 16-eV satellite is found to show a Cu antiresonance, and is assigned to a 1A1g singlet with both holes on the copper sites.
    Shen, M.Y., Yokouchi, T., Koyama, S., and Goto, T.
    Dynamics associated with Bose-Einstein statistics of orthoexcitons generated by resonant excitations in cuprous oxide 1997 Physical Review B
    Vol. 56(20), pp. 13066-13072 
    article DOI  
    Abstract: Orthoexcitonic gas in cuprous oxide is generated by one and two photon resonant excitations at different excitation intensities and at different temperatures between 1.8 and 4.2 K. The experimental results are analyzed by simulation with a Boltzmann equation. When the exciton density is low, the observed luminescence is found to originate from a nonequilibrium excitonic gas where the exciton-LA phonon scattering dominates. When the exciton density is very high, not only the exciton-LA phonon scattering but also the exciton-exciton scattering is important. The observed luminescence consists of two systems: one is from an exciton system that is distributed according to the usual Bose-Einstein statistics with chemical potential μ=0, while the other is from excitons with zero kinetic energy. The two systems were found to be in thermal equilibrium. The latter system might be a form of Bose-Einstein condensation.
    Sherwood, P.M.A.
    Oxidation and corrosion studies by valence band photoemission 1991 Journal of Vacuum Science & Technology A
    Vol. 9(3), pp. 1493-1497 
    article DOI  
    Abstract: A combination of valence band x-ray photoelectron spectroscopy (VXPS) interpreted by X calculations, and x-ray diffraction is discussed as a means of understanding the surface chemistry associated with oxidation and its prevention. The cluster models used to interpret VXPS for oxide systems are discussed, and the spectrum of cuprous oxide is examined in detail. It can be seen that good agreement can be obtained with the valence band spectra of oxidation films and corrosion inhibitor films. Examples are given that show how VXPS can reveal chemical features that cannot be obtained from core x-ray photoelectron spectroscopy.
    Shestatskii, S.N. and Sobolev, V.V.
    Electroreflectance Spectrum of Cuprous Oxide Crystals 1968 Physica Status Solidi (b)
    Vol. 28(2), pp. K131-K133 
    article DOI  
    Abstract: No Abstract.
    Shestatskii, S.N. and Sobolev, V.V.
    Ultraviolet Electroreflectance of Cuprous Oxide 1969 physica status solidi (b)
    Vol. 32(1), pp. K109-K111 
    article DOI  
    Shestatskii, S.N., Sobolev, V.V., Likhobabin, N.P., and Volovenko, L.V.
    Electroabsorption in the Green Exciton Series of Cu2O 1970 Physica Status Solidi (b)
    Vol. 38(2), pp. A131-A133 
    article DOI  
    Shestatskii, S.N., Sobolev, V.V., and Likhobabin, N.P.
    Exciton electro-reflectance of cuprous oxide crystals 1970 Physica Status Solidi (b)
    Vol. 42(2), pp. 669-679 
    article DOI  
    Abstract: The electro-reflectance spectrum of Cu2O single crystals was measured in the region of blue and violet exciton series (5000 to 4000 �) at T = 77.3 �K. Both the modulating voltage Uac and the dc bias voltage Udc were varied. The electro-reflectance structure obtained is due to the electric field effect on the n = 1 and n = 2 exciton lines of the blue and violet exciton series of cuprous oxide. The inversion of the electro-reflectance structure occurs for some values of the ac voltage being different for various dc biases. This phenomenon is due to the presence of surface band bending of Cu2O samples investigated. Agreement was obtained with the basic conclusions of Aspnes and Frova's theory taking into account the influence of the surface field non-uniformity on the line-shapes of the electro-reflectance spectra.
    Shimada, H. and Masumi, T.
    Hall Mobility of Positive Holes in Cu2O 1989 Journal of the Physical Society of Japan
    Vol. 58(5), pp. 1717-1724 
    article DOI  
    Abstract: Hall mobility of photoexcited holes in the + valence band of Cu2O has been measured at low temperatures. On the basis of the theory of carrier-lattice interactions in polyatomic crystals the intrinsic scattering mechanisms of this substance have been clarified, for the first time, in a wide temperature range up to 400 K. From 40 K to 100 K scattering is dominated by the low-frequency LO phonon, ω1. Above 100 K, the effect of the high-frequency LO phonon, ω2, becomes remarkable. Here, ω1=153 cm-1 and ω2=660 cm-1 at 4.2 K. Mobility quenching due to the metastable self-trapping of holes possibly underlies the phenomena above 200 K. Below 40 K, the temperature dependence of mobility can be explained in terms of a combination of the effects of optical, acoustical and neutral impurity scatterings. The magnitude of the deformation potential of the + valence band is estimated to be as small as 0.7±0.3 eV.
    Shindo, K., Goto, T., and Anzai, T.
    Exciton-LO Phonon Scattering in Cu2O 1974 Journal of the Physical Society of Japan
    Vol. 36(3), pp. 753-758 
    article DOI  
    Abstract: Reliable absorption line shape of the several higher members of the yellow exciton series in Cu2O has been measured by the photoelectric method using a monochromator with a large dispersion at 1.8 K, and has been analyzed on the basis of Toyozawa's formula. The origin of the half width is considered to come from the interband scattering of the exciton from the p state to the 1s state by the two modes of L0 phonons. The estimated ratio in the line width of the n-th member to the second member of the exciton series is in agreement with the experimental one.
    Shishiyanu, S.T., Shishiyanu, T.S., and Lupan, O.I.
    Novel NO2 gas sensor based on cuprous oxide thin films 2006 Sensors and Actuators B: Chemical
    Vol. 113(1), pp. 468-476 
    article DOI  
    Abstract: In this paper we present the results concerning the characterization of cuprous oxide thin films fabricated by chemical deposition and rapid photothermal processing (RPP) method. The growth kinetic effects and influence of the RPP temperature on the chemical deposited cuprous oxide thin films microstructures were investigated by scanning electron microscopy and energy dispersive X-ray spectrometry. The effect of the electrical resistivity change of Cu2O thin film layer in the presence of NO2 is used for gas sensing measurements. Cuprous oxide layers are used as NO2 gas sensitive material in a novel gas sensor element. It can be shown from experimental results that chemical bath deposition and rapid photothermal processing not only allows green materials preparation but also improves the performance and reliability over conventional methods of the production of sensors for continuous environmental monitoring.
    Sieberer, M., Redinger, J., and Mohn, P.
    Electronic and magnetic structure of cuprous oxide Cu2O doped with Mn, Fe, Co, and Ni: A density-functional theory study 2007 Physical Review B
    Vol. 75(3), pp. 035203 
    article DOI  
    Abstract: We investigate the effect of transition metal (TM) substitution in cuprous oxide Cu2O on the basis of ab initio calculations employing density-functional theory (GGA+U) . By using the supercell approach, we study the effect of substituting Cu by Mn, Fe, Co, and Ni, assuming both low TM concentrations (3.2%) in a cubic geometry and higher TM concentrations (9.1%) in a trigonal setup. For the elements Mn and Co, magnetic exchange constants up to the fifth nearest neighbor are calculated, assuming both cases, perfect Mn/Co:Cu2O as well as defects in the host such as single copper and oxygen vacancies. Our results clearly show the importance of defects in these materials and thus offer an explanation for various, seemingly opposed, experimental results.
    Siegfried, M.J. and Choi, K.-S.
    Electrochemical Crystallization of Cuprous Oxide with Systematic Shape Evolution 2004 Advanced Materials
    Vol. 16(19), pp. 1743-1746 
    article DOI  
    Abstract: The growth of Cu2O crystals that are electrochemically deposited as micrometer-size crystals with systematically varying fractions of 100 and 111 faces is reported (the Figure depicts cubic crystals). The methodical and homogeneous shape evolution is achieved by tuning the degree of preferential adsorption of sodium dodecyl sulfate on the 111 faces of growing Cu2O crystals through pH variation. Scale bar: 1�&mgr;m.
    Siegfried, M.J. and Choi, K.-S.
    Directing the Architecture of Cuprous Oxide Crystals during Electrochemical Growth 2005 Angewandte Chemie International Edition
    Vol. 44(21), pp. 3218-3223 
    article DOI  
    Abstract: A new level of programmability and freedom in directing the crystal growth of cuprous oxide was demonstrated by controlling the degree of branching and crystal habit in a systematic manner during electrodeposition. Examples of Cu2O crystals in which these features were directed by rationally designing a growth condition and growth history are shown (scale bar=1 mum).
    Singh, D.P., Singh, J., Mishra, P.R., Tiwari, R.S., and Srivastava, O.N.
    Synthesis, characterization and application of semiconducting oxide (Cu2O and ZnO) nanostructures 2008 Bulletin of Materials Science
    Vol. 31, pp. 319-325 
    article URL 
    Sirbu, S.
    Induced excitations in some metal oxides 2008 School: University of Groningen  phdthesis URL 
    Abstract: An optical spectrometer may be a tool unfamiliar to an outsider of the optics community. It can be regarded as a natural evolution of the way we perceive the surrounding environment. Light coming from the sun is reflected or transmitted by objects. The human eye, by measuring this reflected or transmitted light, gains some information about the objects themselves, such as their color, brightness, and shape. Using the same principles, an optical spectrometer is designed to gain even more information. It has a source of light used to send light on some objects, and a hi-tech detector to measure the transmitted or reflected light.
    After the material has been measured, a relation needs to be established between its optical response and its main physical properties. In this thesis we consider the case of solid state materials. These are materials where the atoms are in close proximity to each other, and arranged in repetitive patterns on macroscopic distances, to make a compact structures (a good example is NaCl, kitchen salt). To establish the above mentioned relation the following procedure is followed. First the optical response (transmission, reflectivity, absorption, etc.) at each frequency in the incident light is measured. The result in quantified in terms of the so called dielectric constant of the bulk ε(∞). In a second step, this function is related to the main physical propertied of the measured solid state material, using the knowledge of this particular structure, determined before by different type of measurements, such as for instance X-ray diffraction. Today, optical spectroscopy has become one of the most important standard tools for investigating novel condensed matter materials.

    The aim of the work presented in this thesis is to investigate the low energy excitation spectra and the (induced) phase transitions in transition metal oxides.

    Siripala, W. and Jayakody, J.R.P.
    Vol. 14, pp. 23-27 
    article DOI  
    Abstract: Copper oxide films were cathodically deposited on various metal substrates (Cu, Ti and Pt) using a basic solution of CuSO4, and it is found that they produce n-type photoconductivity in a photoelectrochemical cell. The photoresponse of these films is more pronounced than the previously known thermally grown p-Cu2O films, and the n-type behaviour could be converted to p-type by heating the samples in air. It is tentatively proposed that oxygen ion vacancies in the electrodeposited copper oxide films would result in n-Cu2O.
    Siripala, W., Perera, L.D.R.D., De Silva, K.T.L., Jayanetti, J.K.D.S., and Dharmadasa, I.M.
    Study of annealing effects of cuprous oxide grown by electrodeposition technique 1996 Solar Energy Materials and Solar Cells
    Vol. 44, pp. 251-260 
    article DOI  
    Abstract: Low temperature electrochemical deposition of cuprous oxide from aqueous solutions has been investigated. X-ray diffraction, scanning electron microscopy, optical absorption, and photo-response of liquid/cuprous oxide junctions have been used to study the deposits' crystallographic, morphological, optical, and electrical properties. Effects of annealing in air have been studied using the above mentioned methods. As-deposited cuprous oxide exhibits a direct band gap of 2.0 eV, and shows an n-type behaviour when used in an liquid/solid junction. Annealing below 300°C enhances the n-type photocurrent produced by the junction. Type conversion occurs after heat treatments in air at temperatures above 300°C. No apparent bulk structure changes have been observed during annealing below this temperature, but heat treatments above this temperature produce darker films containing cupric oxide and its complexes with water.
    Siripala, W., Ivanovskaya, A., Jaramillo, T.F., Baeck, S.-H., and McFarland, E.W.
    A Cu2O/TiO2 heterojunction thin film cathode for photoelectrocatalysis 2003 Solar Energy Materials and Solar Cells
    Vol. 77(3), pp. 229-237 
    article DOI  
    Abstract: A thin film heterojunction photocathode was developed consisting of 100 nm of n-type titanium dioxide (TiO2) cathode surface deposited on p-type cuprous oxide (Cu2O). The cuprous oxide was deposited electrochemically on Ti foil. A photocurrent of 0.7 mA/cm2 (at -1 V bias) and an open circuit photovoltage of 460 mV were obtained under an illumination of 700 W/m2. The photoresponse as a function of pH demonstrated that the TiO2 film protected the Cu2O underlayer against corrosion. These results suggest that using a simple and inexpensive heterostucture configuration, the corrosion limitations of Cu2O alone may be overcome while maintaining a relatively high efficiency for photoelectrolysis.
    Šmith, M., Gotovac, V., Aljinović, L., and Lučić-Lavčević, M.
    An investigation of the electrochemical and photoelectrochemical properties of the cuprous oxide/liquid phase boundary 1995 Surface Science
    Vol. 335, pp. 171-176 
    article DOI  
    Abstract: In view of the possible application of cuprous oxide in solar energy conversion its physical properties and photoelectrochemical behavior of the phase boundary between the Cu2O and liquid have been investigated. The composition of galvanostatically deposited films is pure Cu2O, but its structure is disordered. The conductivity is due to carriers hopping between localized energy states. At room temperature thin Cu2O films behave like n-type semiconductors. On the basis of the experimental data an energy scheme for the thin oxide semiconductor film is given. From the representative voltammograms in the dark and under illumination it could be concluded that the currents are changed under illumination and that photodegradation takes place. Some unusual phenomena are discussed on the basis of the properties of the thin oxide/electrolyte phase boundary where surface effects are more pronounced than in the bulk material. The conversion efficiency of the Cu2O photoanode in photoelectrochemical cells is below 1%. An analysis of the causes of this poor performance is given.
    Smyth, F.H. and Roberts, H.S.
    THE SYSTEM CUPRIC OXIDE, CUPROUS OXIDE, OXYGEN 1920 Journal of the American Chemical Society
    Vol. 42(12), pp. 2582-2607 
    article DOI  
    Snoke, D., Wolfe, J.P., and Mysyrowicz, A.
    Quantum saturation of a Bose gas: Excitons in Cu2O 1987 Physical Review Letters
    Vol. 59(7), pp. 827-830 
    article DOI  
    Abstract: Quantum statistics of an ideal gas of Bose particles predicts a phase boundary for Bose-Einstein condensation. The expected relation for the saturated-gas density, n=CT3/2, is observed for an exciton gas in Cu2O by time resolution of the energy spectrum.
    Snoke, D.W., Wolfe, J.P., and Mysyrowicz, A.
    Evidence for Bose-Einstein condensation of excitons in Cu2O 1990 Physical Review B
    Vol. 41(16), pp. 11171-11184 
    article DOI  
    Abstract: Pulsed-laser excitation of naturally grown crystals of Cu2O produces a dense gas of excitons, which exhibits Bose-Einstein quantum statistics. Both orthoexcitons and paraexcitons, split by a 12-meV electron-hole exchange energy, are formed. At high excitation levels, the time-resolved luminescence of orthoexcitons yields a density-temperature relation that follows the phase boundary for Bose-Einstein condensation, n=CT3/2, but no striking evidence for a condensed fraction is observed. We have now measured the time-resolved spectrum of the lower-lying paraexcitons whose luminescence is 1500 times weaker than the orthoexciton luminescence. At intermediate power levels, the paraexciton distribution is more degenerate than the orthoexcitons. The relative intensities of the two species indicate that at high excitation levels the paraexciton density exceeds the critical density for condensation. At these high densities the paraexciton spectrum develops a structure that cannot be explained in terms of the thermalized Bose-Einstein distribution. Time-resolved spatial measurements of the luminescence indicate a rapid nondiffusive expansion of the gas at supersonic velocities that approach the expected ballistic velocities of the excitons. The rapid transport and the concurrent changes in the spectral distribution of paraexcitons may be the first observation of excitonic Bose-Einstein condensation and superfluidity.
    Snoke, D.W. and Wolfe, J.P.
    Picosecond dynamics of degenerate orthoexcitons in Cu2O 1990 Physical Review B
    Vol. 42(13), pp. 7876-7884 
    article DOI  
    Abstract: Previous time-resolved luminescence studies of orthoexcitons in Cu2O have shown a ‘‘quantum saturation’’ behavior. Basically, it was found that for 10-ns laser pulses, which are comparable to the exciton lifetime, the exciton-gas temperature rises along the phase boundary for Bose-Einstein condensation as the density is increased. The microscopic processes that lead to such an unusual effect remained unresolved. To isolate the various kinetic processes, we have now conducted a study using 100-ps pulses, which are short compared with the orthoexciton lifetime. Combined with an increased time resolution, this short-pulse excitation has allowed us to observe some of the intrinsic rates of thermalization and decay of the orthoexcitons. At low-to-intermediate excitation levels, the decay of the gas temperature is found to agree with a model of acoustic-phonon emission, and the deduced exciton-phonon coupling is in basic agreement with that obtained from diffusion experiments. Another principal result is that the decay time of the gas temperature is significantly increased with increasing degeneracy, i.e., at high excitation level. After the short excitation pulse the orthoexcitons follow the Bose-Einstein phase boundary in density and temperature in a way similar to their behavior during the ‘‘steady-state’’ conditions of the long-pulse excitation. We conclude that the temperature rise is not simply due to insufficient thermalization caused by a shortening of the exciton lifetime; at high density there must be a heating mechanism such as Auger recombination.
    Snoke, D.W., Braun, D., and Cardona, M.
    Carrier thermalization in Cu2O: Phonon emission by excitons 1991 Physical Review B
    Vol. 44(7), pp. 2991-3000 
    article DOI  
    Abstract: We have observed the energy distribution of nonthermalized excitons in the semiconductor Cu2O on a time scale of 10 ps following resonant creation by a short (5-ps) laser pulse. We present a model for the change in the energy distribution of carriers as they cool to take on a Maxwell-Boltzmann distribution at the lattice temperature. Emission and absorption of acoustic phonons via the deformation-potential interaction and emission and absorption of nonpolar optical phonons are taken into account in an exact Boltzmann equation that is solved numerically. The model fits the observed distributions well, for a value of the deformation potential in agreement with hydrostatic-pressure and uniaxial-stress measurements. Single-optical-phonon emission is found to be rather slow, with a time scale of about 30 ps. We also present evidence for a fast two-optical-phonon emission process in Cu2O. Finally, we consider the effects of exciton-exciton interactions and obtain an upper bound on the range of exciton-exciton interactions from these experiments.
    Snoke, D.W., Shields, A.J., and Cardona, M.
    Phonon-absorption recombination luminescence of room-temperature excitons in Cu2O 1992 Physical Review B
    Vol. 45, pp. 11693-11697 
    article DOI  
    Snoke, D., Braun, D., and Cardona, M.
    Nonequilibrium exciton kinetics in Cu2O 1992 Journal of Luminescence
    Vol. 53(1-6), pp. 415-418 
    article DOI  
    Abstract: We have observed the energy distribution of nonthermalized excitons in the semiconductor Cu2O on a time scale of 10 ps following near-resonant creation by a short (5ps) laser pulse. We see a non-Maxwellian energy distribution with four discrenible hot-luminescence peaks at early times due to emission of both acoustic and optic phonons, which had previously been identified as multi-phonon Raman scattering lines. We fit the energy distribution of the excitons at all times by numerically integrating an exact Boltzmann equation. From this we deduce the deformation potential for acoustic phonon emission, which agrees with the results of hydrostatic-stress and uniaxial-stress measurements, and we deduce the rate for single optic phonon emission, which turns out to be rather slow, about 30 ps.
    Snoke, D.
    Coherent Exciton Waves 1996 Science
    Vol. 273, pp. 1351-1352 
    article DOI  
    Abstract: Excitons are electrically neutral energetic pairs of electrons and holes, created by the absorption of photons in a solid. These energy-carrying pairs can be used to produce light for microscopes and are used by plants to collect sunlight for photosynthesis. In his Perspective, Snoke describes work carried out at Ecolé Polytechnique in Palaiseau, France, and the University of Ottawa, Canada, in which excitons were produced by stimulated emission. Such processes may someday be used to create a laserlike source of excitons.
    Snoke, D.W. and Negoita, V.
    Pushing the Auger limit: Kinetics of excitons in traps in Cu2O 2000 Physical Review B
    Vol. 61(4), pp. 2904-2910 
    article DOI  
    Abstract: We have measured the Auger recombination rate for excitons in Cu2O trapped in harmonic potential wells created by inhomogeneous stress. The rate is higher than assumed in most previous experiments, but consistent with the rate reported recently by O’Hara et al. [Phys. Rev. B (to be published)]. We find that even given this rate, the orthoexciton density immediately after creation in the well by a short laser pulse may be high enough for Bose condensation, and there is some evidence that this may occur.
    Snoke, D.
    Spontaneous Bose Coherence of Excitons and Polaritons 2002 Science
    Vol. 298, pp. 1368-1372 
    article DOI  
    Abstract: In the past decade, there has been an increasing number of experiments on spontaneous Bose coherence of excitons and polaritons. Four major areas of research are reviewed here: three-dimensional excitons in the bulk semiconductor Cu2O, two-dimensional excitons in coupled quantum wells, Coulomb drag experiments in coupled two-dimensional electron gases, and polaritons in semiconductor microcavities. The unifying theory of all these experiments is the effect of spontaneous symmetry breaking in the Bose-Einstein condensation phase transition.
    Snoke, D. and Kavokin, A.
    Are we there yet? Progress in condensation of quasiparticles 2007 Solid State CommunicationsSpontaneous coherence in exciton systems
    Vol. 144(9), pp. 357-358 
    article DOI  
    Solache-Carranco, H., Juárez-Díaz, G., Esparza-García, A., Brise no-García, M., Galván-Arellano, M., Martínez-Juárez, J., Romero-Paredes, G., and Pe na-Sierra, R.
    Photoluminescence and X--ray diffraction studies on Cu2O 2009 Journal of Luminescence
    Vol. 129, pp. 1483-1487 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) crystals were grown by the two-step crystallization method in air atmosphere conditions from polycrystalline thin copper foils. The method comprises two stages; in the first one the copper plates are oxidized at 1020 °C by some hours in line with its initial thickness. In the second stage, the growth of large crystalline areas is promoted by annealing the Cu2O samples at 1100 °C for long periods. Raman scattering an X-ray measurements demonstrates the existence of the single-phase Cu2O. The effects on the crystalline structure and photoluminescence (PL) response were studied as a function of the conditions used in the second stage of the synthesis method. PL spectra were taken from 10 to 180 K to define the main radiative recombination paths. Besides the near band excitonic transitions, two strong emission bands at 720 and 920 nm associated with relaxed excitons at oxygen and copper vacancies were detected. Both excitonic-vacancy bond transitions presented similar intensities that are related to the growth method. X-ray and Raman scattering measurements help to assess the samples crystalline quality.
    Soon, A., Todorova, M., Delley, B., and Stampfl, C.
    Thermodynamic stability and structure of copper oxide surfaces: A first-principles investigation 2007 Physical Review B
    Vol. 75(12), pp. 125420 
    article DOI  
    Abstract: To obtain insight into the structure and surface stoichiometry of copper-based catalysts in commercially important chemical reactions such as the oxygen-assisted water-gas shift reaction, we perform density-functional theory calculations to investigate the relative stability of low-index copper oxide surfaces. By employing the technique of “ab initio atomistic thermodynamics,” we identify low-energy surface structures that are most stable under realistic catalytic conditions are found to exhibit a metallic character. Three surfaces are shown to have notably lower surface free energies compared to the others considered and could be catalytically relevant; in particular, under oxygen-rich conditions, they are the Cu2O(110):CuO surface, which is terminated with both Cu and O surface atoms, and the Cu2O(111)-CuCUS surface, which contains a surface (coordinatively unsaturated) Cu vacancy, while for the oxygen-lean conditions, the Cu2O(111) surface with a surface interstitial Cu atom is found to be energetically most favorable, highlighting the importance of defects at the surface.
    Soon, A., Cui, X.-Y., Delley, B., Wei, S.-H., and Stampfl, C.
    Native defect-induced multifarious magnetism in nonstoichiometric cuprous oxide: First-principles study of bulk and surface properties of Cu2O 2009 Physical Review B
    Vol. 79, pp. 035205 
    article DOI  
    Abstract: Native defects in cuprous oxide Cu2O are investigated by using first-principles calculations based on density-functional theory. Considering the formation of copper and oxygen vacancies, antisites and interstitials, and a copper split-vacancy complex defect, we analyze the electronic structure and calculate their respective formation energies as a function of the change in Fermi level under both copper-rich and oxygen-rich conditions. We find that, under both growth conditions, the defect with the lowest formation energy is the simple copper vacancy, followed by the copper split-vacancy complex. Both low-energy copper defects produce hole states at the top of the valence band, largely accounting for the p-type conductivity in this material. In spite of the creation of dangling bonds at the nearest-neighbor O atoms, these copper defects are found to be spin neutral. Under oxygen-rich conditions, oxygen interstitials have low formation energies and are found to exhibit a ferromagnetic ordering with a total magnetic moment of 1.38μB and 1.36μB at the octahedral and tetrahedral sites, respectively. Considering the possibility of native defect formation at the surface of this material, we investigate the relative stability of both low- and high-index copper-oxide surfaces by comparing their surface free energies as a function of the change in oxygen chemical potential. Using the technique of ab initio atomistic thermodynamics, we then correlate the dependence of the calculated Gibbs free-surface energy as a function of oxygen pressure and temperature via the oxygen chemical potential. We identify two low-energy surface structures, namely, Cu2O(110):CuO and Cu2O(111)-CuCUS, with the former marginally more stable for oxygen-rich conditions and the latter more stable for oxygen-lean (or copper-rich) conditions. Cu2O(110):CuO is calculated to be nonmagnetic and Cu2O(111)-CuCUS is calculated to be a ferromagnetic ordering, with a total magnetic moment of 0.91μB per defect. With the results for both bulk and surface native defects, we find that under oxygen-lean conditions, a ferromagnetic behavior could be attributed mainly to copper vacancy formation in the (111) surface of Cu2O while under oxygen-rich conditions, low-energy bulk oxygen interstitial defects induce a ferromagnetic character in the same material. This highlights the complementary role of bulk and surface native magnetic defects under different pressure and temperature conditions, especially at the nanoparticle scale where surface properties dominate.
    Spyridelis, J., Stoimenos, J., and Economou, N.
    Optical and Photoconductive Phenomena in Cuprous Oxide 1967 Physica Status Solidi (b)
    Vol. 20(2), pp. 623-628 
    article DOI  
    Abstract: The optical absorption of cuprous oxide is affected by the defect structure and this is most pronounced in the middle of the stability range, indicating that the observed absorption bands are due to aggregates of vacancies. A simultaneous measurement of the photoconductivity leads to a direct relationship between the exciton stimulated photoresponse and the defect structure.
    Starr, C.
    The Copper Oxide Rectifier 1936 Physics
    Vol. 7, pp. 15-19 
    article DOI  
    Abstract: The equilibrium diagram of the copper: copper oxide: oxygen system controls the conditions of formation of the cuprous oxide rectifier. The interface between the cuprous oxide and the copper from which it is formed can be studied with polarized light. Intimate contact exists for more than half the total area. The technique of preparing the rectifier has a marked influence on its characteristics. By using a method of measuring the resistance characteristic which did not cause an error due to current heating at the interface, unusual results were obtained from specimens made under various conditions. Measurement of the thermal conductance of the rectifier disclosed a new physical phenomenon, asymmetrical thermal conductance. This asymmetry is in the direction that would be expected from the electron theory of heat conduction.
    Stecker, K.
    Über die Halbleitereigenschaften des Kupferoxyduls. XII Die Leitfähigkeit des Kupferoxyduls innerhalb des Existenzgebietes bei hohen Temperaturen im Bereich kleiner Drucke 1959 Annalen der Physik
    Vol. 458(1-2), pp. 55-69 
    article DOI  
    Abstract: Es wird gezeigt, daß der bisher bei Sauerstoffdrucken &lt; 10-2 Torr gefundene starke Abfall der elektrischen Leitfähigkeit des
    Kupferoxyduls im Gebiet von 700-1000° C auf fehlerhaften Messungen beruht. Unter Ausschaltung des Fehlers wird im gesamten untersuchten

    Gebiet die Gesetzmäßigkeit mit n &ap; 8 bestätigt und die Austrittsarbeit zu 1,30 eV (0,65 eV) bestimmt.Eine Diskussion des
    Knudsen-Effektes in Bezug auf diese Messungen zeigt, daß er ent gegen den bisherigen Betrachtungen keine Meßwertverfälschung bedingt.Die

    Existenzgrenze Cu2O/CuO wird nochmals bestimmt.

    Suehiro, T., Sasaki, T., and Hiratate, Y.
    Electronic properties of thin cuprous oxide sheet prepared by infrared light irradiation 2001 Thin Solid Films
    Vol. 383(1-2), pp. 318-320 
    article DOI  
    Abstract: Self-supporting sheets of cuprous oxide were fabricated by thermally oxidizing (Cu-->CuO) copper foils and deoxidizing (CuO-->Cu2O) in a chamber filled with O2 gas with focused infrared light irradiation. This method proved to be good for preparing cuprous oxide sheets with high purity and low resistivity.
    Sun, Y., Rivkin, K., Chen, J., Ketterson, J.B., Markworth, P., and Chang, R.P.
    Strain splitting of $1s$ yellow orthoexciton of epitaxial orthorhombic Cu2O films on MgO $[110]$ 2002 Physical Review B
    Vol. 66(24), pp. 245315 
    article DOI  
    Abstract: We investigated the optical properties of epitaxial orthorhomic cuprous oxide films grown on MgO [110]. Absorption measurements show clear excitonic peaks up to n=5p. Photoluminescence at 2 K shows several sharp emission peaks in the vicinity of 610 nm associated with a splitting of various 1s orthoexciton energy levels. The evolution of the peaks with temperature indicates that three peaks at higher energy are due to direct recombination of 1s yellow orthoexcitons and three corresponding peaks at lower energy are their phonon replicas. The symmetry of each level is identified by the polarization properties of their photoluminescence emissions. The observed splitting of the energy levels is used to calculate the coherency strain based on an earlier-parametrized theory for the level splitting by Waters et al. based on the known symmetry of the electronic states. This predicted strain is compared with that determined by x-ray diffraction measurements of the measured lattice parameters.
    Sun, Y., Wong, G.K.L., and Ketterson, J.B.
    Study of the 1s orthoexciton luminescence in Cu2O under two-photon excitation 2004 Journal of Luminescence
    Vol. 110(3), pp. 125-134 
    article DOI  
    Abstract: We have studied the luminescence of 1s orthoexcitons in Cu2O under both resonant and non-resonant two-photon excitation. The intensity of the luminescence was enhanced while resonantly exciting at the 1s or 2s orthoexciton levels. The direct and phonon-assisted emissions were observed over a wide range of temperatures (1.8-294�K) under two-photon resonant excitation. The phonon-assisted spectra can be well fit with a Maxwellian distribution with a fitting temperature close to the lattice temperature. The integrated intensity shows a minimum at 20�K and a maximum around 180�K. The existence of the direct emission feature enables us to deduce the temperature dependent bandgap and the orthoexciton line width directly up to relatively high temperatures. The red-shift of the orthoexciton energy and the increase of its line width as the temperature increases are interpreted as a temperature dependence of the real and imaginary parts of the exciton self energy.
    Sun, L. and Yang, J.C.
    The low-temperature initial oxidation stages of Cu$(100)$ investigated by in situ ultra-high-vacuum transmission electron microscopy 2005 Journal of Materials Research
    Vol. 20, pp. 1910-1917 
    article DOI  
    Abstract: The nucleation and growth of Cu2O islands due to Cu(100) oxidation at temperatures from 200 to 350 °C have been observed by in situ ultra-high-vacuum transmission electron microscopy. For this temperature range, epitaxial Cu2O islands form a triangular shape with rounded edges when Cu(100) is exposed to dry oxygen at 5 × 10-4 Torr in situ. Our initial analysis on the nucleation and growth of these three-dimensional Cu2O islands agrees well with the heteroepitaxial model of surface diffusion of oxygen.
    Sun, F., Guo, Y., Song, W., Zhao, J., Tang, L., and Wang, Z.
    Morphological control of Cu2O micro-nanostructure film by electrodeposition 2007 Journal of Crystal Growth
    Vol. 304(2), pp. 425-429 
    article DOI  
    Abstract: Novel well-defined cuprous oxide (Cu2O) thin films are synthesized on indium-doped tin oxide (ITO) covered glass substrates by electrochemical deposition, with cationic surfactant, cetyl trimethylammonium bromide (CTAB) as shape controlled agent. The effects of the quantity of CTAB, the temperature and concentration of electrolyte were studied. It was shown that the morphology evolved from flower-leaves to spheres with increasing quantity of CTAB, which indicated that the morphology varied with the CTAB concentration. Furthermore, the optical properties of Cu2O films was investigated and found that Cu2O film composed of shagginess spheres have better photoluminescence (PL) properties. Also, the Cu2O film can be used as substrates for functional applications.
    Sun, J.-L., Xu, J., and Zhu, J.-L.
    Oxidized macroscopic-long Cu nanowire bundle photoconductor 2007 Applied Physics Letters
    Vol. 90(20), pp. 201119 
    article DOI  
    Abstract: Using a solid electrolyte RbCu4Cl3I2 thin film and a controlled constant current electric field, the authors have directly fabricated macroscopic-long Cu nanowire bundles. Their structural characters have been described at different scales. The oxidation behavior of macroscopic-long Cu nanowire bundles containing thousands of straight and dendritic Cu nanowires was studied using x-ray photoelectron spectroscopy. Benefiting from the oxidized macroscopic-long Cu nanowire bundles, they have experimentally explored photoinduced conductivity in the bundle upon illumination with a 532 nm laser beam, and observed that it can be regarded as a photoconductor with high sensitivity and fast response.
    Sun, B.-Z., Chen, W.-K., Wang, X., and Lu, C.-H.
    A density functional theory study on the adsorption and dissociation of N2O on Cu2O$(111)$ surface 2007 Applied Surface Science
    Vol. 253(18), pp. 7501-7505 
    article DOI  
    Abstract: Density functional theory has been employed to investigate the adsorption and the dissociation of an N2O at different sites on perfect and defective Cu2O(1�1�1) surfaces. The calculations are performed on periodic systems using slab model. The Lewis acid site, CuCUS, and Lewis base site, OSUF are considered for adsorption. Adsorption energies and the energies of the dissociation reaction N2O�-->�N2�+�O(s) at different sites are calculated. The calculations show that adsorption of N2O is more favorable on CuCUS adsorption site energetically. CuCUS site exhibits a very high activity. The CuCUS-N2O reaction is exothermic with a reaction energy of 77.45�kJ�mol-1 and an activation energy of 88.82�kJ�mol-1, whereas the OSUF-N2O reaction is endothermic with a reaction energy of 205.21�kJ�mol-1 and an activation energy of 256.19�kJ�mol-1. The calculations for defective surface indicate that O vacancy cannot obviously improve the catalytic activity of Cu2O.
    Sun, F., Guo, Y., Tian, Y., Zhang, J., Lv, X., Li, M., Zheng, Y., and Wang, Z.
    The effect of additives on the Cu2O crystal morphology in acetate bath by electrodeposition 2008 Journal of Crystal Growth
    Vol. 310(2), pp. 318-323 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) thin films were formed on indium-doped tin oxide (ITO) covered glass substrates by cathodic deposition of cupric acetate. The influence of additives on crystal morphology of Cu2O was studied in acetate bath. We found that the simple salts contained Cl- ions in electrolyte could change the crystal morphology. It was shown that the morphology evolved from star like to cube like by increasing the concentration of Cl- ions of the capping agents, which indicated that Cu2O crystal morphology varied with the Cl- ions concentration.
    Surnev, L.
    On the Long Period Photoconductivity of Cu2O 1969 Physica Status Solidi (b)
    Vol. 31(2), pp. 557-564 
    article DOI  
    Abstract: The slow photoconductivity of Cu2O has been studied. The results obtained can be explained by assuming the existence of three types of traps. The first type contains the highest levels in the forbidden gap. They create the fast component (tau &ap; 10-4 s) of the photoconductivity at room temperature. Levels lying 0.7 eV below the bottom of the conduction band correspond to the second type of traps. They cause a reversible slow component at temperatures below 130 �C. The traps associated with the deepest levels (1.35 eV) produce an irreversible slow component of the photoconductivity at temperatures below 120 �C. The close correlation between the photoconductivity components leads to the assumption that all three types of traps are concentrated on definite sites of the sample. For that reason, with the filling up of traps, barriers are formed in the vicinity of these sites. These barriers determine the kinetics and extent of filling of the traps.
    Sutter, E.M.M., Fiaud, C., and Lincot, D.
    Electrochemical and photoelectrochemical characterization of naturally grown oxide layers on copper in sodium acetate solutions with and without benzotriazole 1993 Electrochimica Acta
    Vol. 38(10), pp. 1471-1479 
    article DOI  
    Abstract: The aim of this work is the characterization of as-grown oxide layers of copper in aerated sodium acetate solutions, in relation to the understanding of the mechanism of protection in the presence of benzotriazole, which is a well known inhibitor of corrosion. The growth and the characteristics of the film at rest potential are studied using cathodic stripping analysis in a deaerated solution. Its properties are determined by using the photoelectrochemical technique. It is shown that in BTA solution, the photoactive layer is the same as without BTA, giving the same optical indirect transitions at 2.6 and 1.9 eV, its thickness being in the range of a few nm. Both cathodic and anodic photocurrents are generated and the particular dependence of the spectral response as a function of potential is evidenced and explained. At the rest potential both photocurrents are superimposed. The layer is attributed to cuprous oxide, weakly modified with BTA. In the presence of BTA, changes in the reduction curves are observed and special attention is paid to a cathodic wave in excess, specific to BTA-aerated solutions. The formation of a polymeric copper(I)-BTA outer film is suggested for the formation of a Cu(II)-superoxide complex related to the uptake of molecular dioxygen.
    Switzer, J.A., Hung, C.-J., Huang, L.-Y., Switzer, E.R., Kammler, D.R., Golden, T.D., and Bohannan, E.W.
    Electrochemical Self-Assembly of Copper/Cuprous Oxide Layered Nanostructures 1998 Journal of the American Chemical Society
    Vol. 120(14), pp. 3530-3531 
    article DOI  
    Switzer, J.A., Hung, C.-J., Huang, L.-Y., Miller, F.S., Zhou, Y., Raub, E.R., Shumsky, M.G., and Bohannan, E.W.
    Potential oscillations during the electrochemical self-assembly of copper/cuprous oxide layered nanostructures 1998 Journal of Materials Research
    Vol. 13, pp. 909-916 
    article DOI  
    Abstract: Layered nanostructures of copper metal and cuprous oxide are electrodeposited from alkaline solutions of Cu(II) lactate at room temperature. No subsequent heat treatment is necessary to effect crystallization. The electrode potential spontaneously oscillates during constant-current deposition. At a fixed current density the oscillation period decreases as either the pH or temperature is increased. The oscillations are periodic in stirred solution, but show period doubling and evidence of quasi-periodic or chaotic behavior in unstirred solution. The phase composition and resistivity of the films can be controlled by varying the applied current density. The resistivity of the films can be varied over ten orders of magnitude. Scanning electron microscopy shows that the films are layered.
    Switzer, J.A., Maune, B.M., Raub, E.R., and Bohannan, E.W.
    Negative Differential Resistance in Electrochemically Self-Assembled Layered Nanostructures 1999 The Journal of Physical Chemistry B
    Vol. 103(3), pp. 395-398 
    article DOI  
    Abstract: Resonant tunneling devices are used for ultrahigh-speed applications. In this work, tunnel junctions based on copper metal (Cu) and cuprous oxide (Cu2O) are electrochemically self-assembled from aqueous solution in an oscillating system. The Cu2O layer thickness (L) is tuned from 0.8 to 2.8 nm by simply changing the applied current density. The layered structures show sharp negative differential resistance (NDR) signatures at room temperature in perpendicular transport measurements, and the NDR maximum shifts to higher bias with a 1/L2 dependence as the Cu2O layer is made thinner. The results are consistent with resonant tunneling from Cu into hole states in the valence band of quantum-confined Cu2O through thin spacecharge regions on each side of the Cu2O.
    Tabuchi, N. and Matsumura, H.
    Control of Carrier Concentration in Thin Cuprous Oxide Cu2O Films by Atomic Hydrogen 2002 Japanese Journal of Applied Physics
    Vol. 41, pp. 5060-5063 
    article DOI  
    Abstract: A stable cuprous oxide Cu2O film is prepared by low-temperature oxidation of a sputtered copper (Cu) thin film at 300°C. Although the carrier concentration in Cu2O is determined by the excessive oxygen (O) concentration, the concentration of such O atoms is controlled by the exposure to atomic hydrogen (H) generated by the catalytic reaction between the heated tungsten catalyst and H2 gas. By this method, the carrier concentration in a 100-nm-thick Cu2O film is decreased from 1 ×1016 cm-3 to 2 ×1015 cm-3 and the Hall effect mobility is increased from 5.6 cm2/Vs to 28.9 cm2/Vs. Atomic H exposure is a useful tool for improving the properties of Cu2O.
    Tanaka, H., Shimakawa, T., Miyata, T., Sato, H., and Minami, T.
    Electrical and optical properties of TCO/Cu2O heterojunction devices 2004 Thin Solid Films
    Vol. 469, pp. 80-85 
    article DOI  
    Abstract: This report describes the electrical and photovoltaic properties in heterojunction devices consisting of a cuprous oxide (Cu2O) sheet and a transparent conducting oxide (TCO) thin film, such as In2O3, ZnO, In2O3:Sn (ITO), ZnO:Al (AZO) or AZO–ITO (AZITO) multicomponent oxide, prepared by pulsed laser deposition (PLD). Undoped In2O3–Cu2O heterojunctions prepared by PLD exhibited ohmic current–voltage (I–V) characteristics. The ZnO–Cu2O and AZO–Cu2O devices exhibited better rectifying I–V characteristics and photovoltaic properties than the ITO–Cu2O devices. It was found that the obtainable I–V characteristics and photovoltaic properties were considerably affected by the TCO film deposition conditions. An open-circuit voltage (VOC) of 0.4 V, a short-circuit current density (JSC) of 7.1 mA/cm2, a fill factor (F.F.) of 0.4 and an energy conversion efficiency (η) of 1.2% were obtained in an AZO–Cu2O device under AM2 solar illumination. The VOC, JSC, F.F. and η obtained in AZITO–Cu2O heterojunctions increased as the Zn/(Zn+In) atomic ratio was increased.
    Tang, Y., Chen, Z., Jia, Z., Zhang, L., and Li, J.
    Electrodeposition and characterization of nanocrystalline cuprous oxide thin films on TiO2 films 2005 Materials Letters
    Vol. 59(4), pp. 434-438 
    article DOI  
    Abstract: The grain size in cuprous oxide (Cu2O) thin films is a key to improve the performance of solar application devices. In this paper, electrochemical deposition of nanocrystalline Cu2O thin films on TiO2 films coated on transparent conducting optically (TCO) glass substrates by cathodic reduction of cupric acetate has been investigated. The deposition kinetics of nanocrystalline Cu2O thin films were studied and the parameters limiting the deposition of the films were determined. Pure Cu2O deposited at bath temperature between 0 and 30 °C produced spherically shaped grains with 40~50 nm diameters which have not been reported previously. The effect of pH was studied and a solution with a pH between 5.5 and 6 was found to be best. The effect of annealing on bulk structure, electrical resistivity, and optical absorption of nanocrystalline Cu2O thin films was also studied and the results were discussed.
    Tapiero, M., Zielinger, J.P., and Noguet, C.
    Electrical Conductivity and Thermal Activation Energies in Cu2O Single Crystals 1972 Physica Status Solidi (a)
    Vol. 12, pp. 517-520 
    article DOI  
    Abstract: A systematic investigation, performed on some fifty single crystals, between -40 and 250 °C shows that the values of the bulk resistivity v (20 °C) range from 103 to 1013 cm and that the activation energies lie between 0.1 and 1 eV. These values depend on the conditions of the cooling after oxydation and of high vacuum annealing. A quasi-continuous relation between E and lg v (20 °C) is found.
    Tapiero, M., Zielinger, J.P., and Noguet, C.
    Conductibilité Électrique De Cu2O. I. État Actuel Des Recherches Et Méthodes De Mesures 1972 Annales de Physique
    Vol. 7, pp. 85-94 
    article URL 
    Tapiero, M., Zielinger, J.P., and Noguet, C.
    Photomemory Effect in Cu2O Single Crystals. Phenomenology and Interpretation 1976 Physica Status Solidi (a)
    Vol. 33, pp. 155-166 
    article DOI  
    Abstract: Various new experimental aspects of the photomemory effect in Cu2O single crystals are investigated. They are interpreted on the basis of the model previously worked out for the electrical conductivity. The pre-illumination of a sample increases its bulk conductivity (by a factor up to 104) and shifts downwards the Fermi level (by an energy up to 0.3 eV). This excitation is explained in terms of electron trapping. Direct evidences reveal the existence of four trapping levels. The saturation of the excitation is attributed to the presence, in the acceptor distribution, of strong recombination levels. The study of the wavelength dependence of the photoexcitation allows to confirm the proposed energy diagram and to precise the position of the recombination levels. Finally, the effect of excitation on the Hall mobility is investigated.
    Tapiero, M., Noguet, C., Zielinger, J.P., Schwab, C., and Pierrat, D.
    Conversion photovoltaïque dans Cu2O 1979 Revue de Physique Appliquée
    Vol. 14, pp. 231-236 
    article DOI  
    Abstract: Cu/Cu2O and Cu2O/Cu junctions have been investigated for low cost photovoltaic solar energy conversion. The best conditions found for the formation of frontwall (deposition of Cu by evaporation or sputtering) and backwall (Cu partially oxidized) cells as well as the means to lower the series resistance, are described. Current-voltage characteristics give barrier heights always near 0.7 V and, depending to the mode of preparation, n-values of about 3 or 6 : this implies the existence of interfacial states. The limited cell performances are attributed to inhomogeneities in the junctions and to the low value of the measured diffusion length (1 to 2 μm).
    Tayagaki, T., Mysyrowicz, A., and Kuwata-Gonokami, M.
    The Yellow Excitonic Series of Cu2O Revisited by Lyman Spectroscopy 2005 Journal of the Physical Society of Japan
    Vol. 74(5), pp. 1423-1426 
    article DOI  
    Abstract: We report on the observation of the yellow exciton Lyman series up to the fourth term in Cu2O by time-resolved mid-infrared spectroscopy. The dependence of oscillator strength on the principal quantum number n can be well reproduced using the hydrogenic model including an AC dielectric constant, and precise information on the electronic structure of the 1s exciton state can be obtained. A Bohr radius a1s=7.9 Å and a 1s–2p transition dipole moment µ1s–2p=4.2 eÅ were found.
    Taylor, J.C.W. and Weichman, F.L.
    Role of Excitons in the Luminescence of Cuprous Oxide 1969 Physical Review
    Vol. 185(3), pp. 1214-1217 
    article DOI  
    Abstract: Evidence is presented on the nature of the recombination center necessary for the infrared luminescence of Cu2O. By comparing luminescence, photoconductivity, and optical absorption, the excitonic origins of the luminescent decay are confirmed, and in particular, the presence of indirect transition processes in the region of the n=2 exciton of the yellow series is observed. Good agreement is also found between the observed luminescence and Elliott's theory of optical absorption, with particular reference to the exciton line asymmetry. The information obtainable from the excitation spectrum of luminescence over and above the data obtained from optical absorption and photoconductivity is discussed.
    Taylor, J.C.W. and Weichman, F.L.
    Raman Effect in Cuprous Oxide Compared with Infrared Absorption 1971 Canadian Journal of Physics
    Vol. 49(5), pp. 601-605 
    article URL 
    Abstract: A complex Raman spectrum of Cu2O has been measured using the Kr laser line at 6471 Å, and comparison with the infrared absorption spectrum is made. An F2g Raman active phonon, postulated from symmetry considerations and infrared absorption measurements to lie at either 606 or 181 cm−1, could not be observed. Strong lines are, however, observed at 220, 204, and 192 cm−1.
    Taylor, J.C.W., Weichman, F.L., and McClung, R.E.D.
    Electron Paramagnetic Resonance in Cu2O Compared with Other Semiconducting Properties 1971 Canadian Journal of Physics
    Vol. 49, pp. 1275-1283 
    article URL 
    Abstract: Electron paramagnetic resonance spectra have been observed in single crystals of Cu2O at 4.2 °K. Six samples cut from the same starting material were individually heated under a wide range of vacuum conditions and comparison was made between the observed e.p.r. spectrum and the luminescence, activation energy, and photoconductivity in the same sample. No direct relationships between e.p.r. spectra and the luminescence and photoconductivity were found although a good correlation between the complexity of the e.p.r. spectra and the room temperature activation energy was observed.
    Taylor, T.N. and Martin, J.A.
    Reaction of vapor-deposited aluminum with copper oxides 1991 Journal of Vacuum Science & Technology A
    Vol. 9(3), pp. 1840-1846 
    article DOI  
    Abstract: Interfaces formed by controlled deposition of Al on Cu oxides at 300 K have been characterized using Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). When Al is deposited onto a thin oxide grown on Cu(110) by atmospheric exposure, it completely scavenges the oxygen from the substrate material, increasing the O(1s) binding energy by 2.0 eV to give the value found for atmospheric oxidation of a thin Al film. Similar oxygen behavior is seen for Al deposition on sputter-deposited CuO with an enriched oxygen surface region, where multilayers of Al erase the shakeup satellites in the Cu(2p) region of the XPS spectrum to give features like those exhibited by Cu2O or metallic Cu. Having calibrated the fluence of the Al source with Rutherford backscattering spectrometry, the attenuation of the Cu 2p1/2 satellite after approximately one monolayer of Al deposition can be associated with oxygen reduction effects in the top 20 Å of the CuO. Approximately 7–8 equivalent monolayers of Al are converted to an oxide in the initial rapid reaction process. Further deposition leads to progressive development of the metallic Al signature in both the XPS and AES spectra. These measurements clearly demonstrate the dominant role played by Al, a strong oxide former, when it is placed in intimate contact with the distinctively weaker Cu oxide.
    Tazenkov, B.A. and Gruzdev, F.A.
    Positive and negative photomemory in cuprous oxide 1974 Soviet Physics - Solid State
    Vol. 16, pp. 460 
    Teh, C.K. and Weichman, F.L.
    Photoluminescence and optical absorption studies of the effects of heat treatment on cuprous oxide 1983 Canadian Journal of Physics
    Vol. 61, pp. 1423-1427 
    article URL 
    Abstract: The defects responsible for the short-wave (720 nm) and medium-wave (820 nm) luminescence in cuprous oxide can be created by annealing the crystal at a temperature of 1050 °C under low oxygen pressures. The annihilation of these defects has been observed from the photoluminescence and optical absorption measurements after the crystal has been subjected to a second annealing in the temperature range of about 750 °C under a reducing atmosphere. From the photoluminescence measurements, the density of these defects is found to decrease exponentially as a function of annealing time, as manifested by the reduction in the luminescent intensity. The rate of reduction in intensity is also found to increase with annealing temperature.
    Because the defects responsible for the luminescence are ascribed to various forms of oxygen vacancies, we believe the decrease in luminescence is due to a reduction in the oxygen vacancies resulting from the formation of copper precipitates in the crystal. The short-wave and medium-wave emissions, which are ascribed to different types of oxygen vacancies, are found to have different activation energies of diffusion.
    Teh, C.K., Tin, C.C., and Weichman, F.L.
    A new method of Analysis of Photoluminescence decay curves 1986 Journal of Luminescence
    Vol. 35, pp. 17-23 
    article DOI  
    Abstract: We describe here an alternative method of analyzing luminescence decay data, which is less computer-time-consuming than the more commonly used non-linear least-squares method.
    The method, which is based on the method used in deep-level transient spectroscopy, involves measuring the luminescent intensity at two different instants of time and looking for the occurrence of peaks when the differential luminescent intensities are plotted as a function of temperature.
    We applied this method of analysis to the study of the medium-wave (820 nm) luminescence in Cu2O, and found an activation energy E = 0.27 (±0.01) eV. The result obtained by non-linear least-squares analysis was 0.29 (±0.03) eV. The close agreement between the results shows the validity of using this new method of analysis.
    The potential use of this method is in the characterization of defect levels in semiconductors by comparing peaks in the differential luminescent intensity versus temperature curves.
    Tennakone, K., Fernando, C.A.N., Kariapper, M.S., and Dewasurendre, M.
    Stabilisation of photoelectrochemical cells based on p type semiconductors by platinum deposition 1986 Journal of Physics D
    Vol. 19(6), pp. L125-L127 
    article DOI  
    Abstract: The cuprous oxide photocathode in the redox electrolyte I - /I 3 - is found to be stabilised by submonolayer quantities of platinum deposited on the surface. The mechanism of stabilisation is discussed.
    Tertian, L., Hokim, D., and Rivière, J.P.
    Transformations in thin foils of cuprous oxide as observed in an electron microscope 1978 Journal de Physique
    Vol. 39, pp. 1135-1139 
    article DOI  
    Abstract: Investigating (001) and (011) oriented monocrystalline thin foils of Cu 2O in a conventional electron microscope enabled us to observe, depending on the irradiation conditions, either the formation of Cu precipitates oriented on Cu2O, or a partial transformation into polycrystalline unoriented CuO. These transformations are interpreted as the result of a local heating under the electron beam, caused by the low thermal conductivity of the sample.
    Thobor, A. and Pierson, J.F.
    Properties and air annealing of paramelaconite thin films 2003 Materials Letters
    Vol. 57, pp. 3676-3680 
    article DOI  
    Abstract: Paramelaconite (Cu4O3) films were deposited on glass and silicon substrates by magnetron sputtering of a copper target in reactive Ar–O2 mixtures. Two sputtering modes were investigated in this paper: radiofrequency (RF) and direct current (DC). Using both modes, paramelaconite single phase can be formed in a limited deposition condition range. The growth rate of this phase is high compared to that of the CuO films deposited in the same reactor. The texture of the paramelaconite film is strongly dependant on the sputtering mode and on the deposition conditions. Some of the properties of RF sputtered Cu4O3 films were investigated: optical band gap and electrical resistivity at room temperature. The Cu4O3 films were annealed in air at temperatures ranging from 250 to 350 °C.
    Tiano, W., Dapiaggi, M., and Artioli, G.
    Thermal expansion in cuprite-type structures from $10K$ to decomposition temperature: Cu2O and Ag2O 2003 Journal of Applied Crystallography
    Vol. 36, pp. 1461-1463 
    article DOI  
    Abstract: The thermal expansion of two isostructural oxides, Cu2O and Ag2O, has been measured from 10 K to their respective decomposition temperatures by means of high-resolution X-ray powder diffraction. The thermal behaviours of the two oxides are different. Cuprite has a negative thermal expansion up to about 200 K, and above this temperature it becomes positive. Ag2O, on the other hand, has a negative thermal expansion up to its decomposition temperature. A comparison with EXAFS data in the same temperature range shows that the observed difference between the thermal expansion regimes of the two compounds can be ascribed to the vibrational behaviour of the Cu and Ag atoms and, in the ultimate analysis, to the different rigidities of the metal–oxygen bonds.
    Timm, H.
    Thermodiffusion in binären und ternären Oxiden 1999 School: University of Hannover  phdthesis URL 
    Timm, H. and Janek, J.
    On the Soret effect in binary non stoichiometric oxides --- kinetic demixing of cuprite in a temperature gradient 2005 Solid State Ionics
    Vol. 176, pp. 1131-1143 
    article DOI  
    Abstract: The Soret effect in nonstoichiometric copper(I)-oxide (cuprite, Cu2−δ O) has been studied experimentally by means of non-isothermal solid state galvanic cells (thermocells) under different boundary conditions. At high temperatures and high oxygen activities, copper metal migrates down the temperature gradient and a gradient in the nonstoichiometry is established under stationary conditions. The heat of transport of copper metal is determined as Q*Cu≈180 kJ/mol at a temperature of 1000 °C and at an oxygen activity of log aO2=−2.95. This result agrees with recent theoretical simulations of the heat of transport of atoms migrating via a vacancy mechanism. These predict a positive sign of the heat of transport and a considerably larger value than the activation energy for the atomic jumps.
    Togashi, T., Hitaka, H., Ohara, S., Naka, T., Takami, S., and Adschiri, T.
    Controlled reduction of Cu$_2^+$ to Cu$^+$ with an N,O-type chelate under hydrothermal conditions to produce Cu2O nanoparticles 2010 Materials Letters
    Vol. 64(9), pp. 1049-1051 
    article DOI  
    Abstract: N,O-type organic chelates reduced coordinated Cu2+ ions under hydrothermal reaction conditions to produce Cu2O/CuO nanoparticles. Chelates in which the N and O atoms are closely spaced produced smaller amounts of CuO nanoparticles, indicating their higher ability to reduce Cu2+ ions to Cu+ ions. [Cu(Gly)2]2 with the shortest ligand chain length produced only Cu2O nanoparticles and, therefore, can be used as a single molecule precursor for the synthesis of Cu2O nanoparticles.
    Tolstoi, N.A. and Bonch-Bruevich, V.A.
    Luminescence of Oxygen Vacancies In Cuprous Oxide 1971 Soviet Physics - Solid State
    Vol. 13, pp. 1135-1137 
    Tomlinson, W.J. and Yates, J.
    THE DIFFUSION OF Cu IN COPPER(I) OXIDE 1977 Journal of Physics and Chemistry of Solids
    Vol. 38, pp. 1205-1206 
    article DOI  
    Toth, R.S., Kilkson, R., and Trivich, D.
    Preparation of Large Area Single--Crystal Couprous Oxide 1960 Journal of Applied Physics
    Vol. 31, pp. 1117-1121 
    article DOI  
    Abstract: Large area single crystals of Cu2O were grown by the process of high temperature annealing. Cu2O was prepared in finely polycrystalline form by the complete oxidation of Cu plate in air at temperatures of 1020°C to 1050°C. Subsequent annealing of the polycrystalline plates at higher temperatures allowed secondary recrystallization to occur. Single‐crystal grains having surface areas larger than 1 in.2 were grown consistently on Cu2O plates having thicknesses of 0.010 in. to 0.060 in. In some cases, entire polycrystalline plates were transformed into single crystals, and as a result, individual single crystals having surface areas of 3 in.2 and larger were obtained. The annealing temperature and the annealing time were found to depend markedly on the plate thickness. Thick plates required lower temperatures and longer annealing times than the thinner plates. X‐ray analysis of the large grains verified that they were single crystals without excess strain, and indicated preferred orientation, with the (211) and (311) planes predominating. Resistance profile measurements at room temperature on quenched samples showed that a variation in resistance exists through the thickness of the plate.
    Toth, R.S., Kilkson, R., and Trivich, D.
    Electrical Conductivity of Single-Crystal Cuprous Oxide at High Temperatures 1961 Physical Review
    Vol. 122, pp. 482-488 
    article DOI  
    Abstract: The electrical conductivity of single-crystal Cu2O was measured in the temperature range of 1100° to 500°C in oxygen pressures from 152 mm to 10-5 mm of Hg. The logσ vs logP(O2) curves were found to be linear between the oxygen pressures of 50 mm and 10-2 mm, with an average slope of 0.1420, or approximately 1/7. These curves exhibit a radical change in slope at O2 pressures below 10-2 mm.
    The plots of logσ vs 1/T at constant oxygen pressure were found to be linear and the activation energies obtained from the slopes of these plots have an average value of 0.65 ev at O2 pressures between 50 mm and 10-2 mm. At O2 pressures of 10-3 mm to 10-4 mm, the activation energy increases sharply to a value of 1.05 ev. The activation energy obtained from the measurement of single-crystal Cu2O in air at temperatures from 1020°C to 1100°C was found to have an average value of 0.767 ev.
    An explanation for the physical significance of the activation energies obtained is suggested and the models proposed to explain the dependence of the electrical conductivity on the O2 pressure are considered.
    Toyozawa, Y.
    Interband effect of lattice vibrations in the exciton absorption spectra 1964 Journal of Physics and Chemistry of Solids
    Vol. 25(1), pp. 59-71 
    article DOI  
    Abstract: A general theory of the line shape of exciton absorption spectra is presented, in which the interband as well as intraband effects of exciton-phonon coupling are exactly taken into account. Two equivalent expressions for the line shape are given. The first one, which can be obtained in a heuristic way starting from the second order perturbation theory for the indirect process, but is derived exactly with the use of generalized damping theory, contains, in the energy denominator, the shift and decay matrix which has non-diagonal elements between different exciton bands. Diagonalization of the renormalized energy matrix leads to the second expression--the additivity rule. According to this rule, the whole of the exciton spectra can be decomposed into components, each of which is of asymmetric Lorentzian shape if the width is sufficiently small and the energy dependences of renormalized quantities can be neglected within this width. Not only the results obtained previously, but also various higher order effects are included in the general expressions. Comparison of theory with observations, and a few remarks useful for the analysis of exciton spectra, will be made.
    Trauernicht, D.P. and Wolfe, J.P.
    Drift and diffusion of paraexcitons in Cu2O: Deformation-potential scattering in the low-temperature regime 1986 Physical Review B
    Vol. 33, pp. 8506-8521 
    article DOI  
    Abstract: The diffusion constant and drift mobility of paraexcitons in Cu2O have been determined by the use of time-resolved luminescence imaging. Extremely large diffusion constants (D≊1000 cm2/s) and drift mobilities (μ≊107 cm2/eV s) are measured at 1.2 K. Both D and μ exhibit very rapid and unusual temperature dependences which vary with applied stress. Calculations described here show that these properties can be attributed to the novel character of paraexcitons in Cu2O. Under zero stress this exciton is expected to couple mainly to longitudinal-acoustic phonons, which have a rather large velocity (≊4.5×105 cm/s). Due to the large excitonic mass (m*≃3m0), the thermal ve- locity [(3kBT/m*)1/2] of the paraexcitons at T≲3 K is slower than this sound velocity, causing a freeze-out of the phonon-emission process. A rapid increase in scattering time is expected as the temperature is lowered further, which is in agreement with the data at zero or low stress. As stress is applied, the paraexciton wave function is altered, allowing a coupling to the transverse-acoustic phonons, which have a velocity (≊1.2×105 cm/s) smaller than the exciton thermal velocity. Transverse-phonon emission thus reduces the exciton mobility and produces a more nearly T-3/2 dependence, as predicted for deformation-potential scattering in the high-temperature limit. We believe that these are the first observations of the low-temperature regime of deformation-potential scattering.
    Trauernicht, D.P., Wolfe, J.P., and Mysyrowicz, A.
    Thermodynamics of strain-confined paraexcitons in Cu2O 1986 Physical Review B
    Vol. 34(4), pp. 2561-2575 
    article DOI  
    Abstract: The thermodynamic behavior of long-lived paraexcitons confined to a parabolic potential well is examined. The potential well is produced by a Hertzian contact stress. A wavelength-tunable dye laser is used to create excitons directly in the potential well or at any other localized point inside the crystal. Spectral and spatial distributions of the exciton recombination luminescence are measured for cw and pulsed excitation. The possibility of Bose-Einstein condensation of these long-lived excitons is examined both theoretically and experimentally. We calculate the spectral and spatial distribution of luminescence from a gas of noninteracting particles in a three-dimensional harmonic-oscillator well. The results are markedly different for direct (no-phonon) and indirect (phonon-assisted) recombination. The calculated spectra are compared to the data for moderate cw excitation at Tbath=2–4.2 K. Taken alone, the no-phonon spectra suggest that the excitonic gas is in the quantum regime; however, this conclusion is shown to be inconsistent with the estimated density of the gas. A consistent interpretation of all spectral and spatial distributions is possible, however, if one assumes Maxwell-Boltzmann statistics and takes into account the rapidly changing paraexciton intensity with applied stress. From time- and space-resolved studies of the orthoexciton and paraexciton luminescence, plausible causes for a saturation of paraexciton density in the strain well are deduced. First, an Auger-like recombination of colliding paraexcitons seems to limit their density—an idea supported by the observed power dependence of orthoexciton and paraexciton signals. Secondly, an anomalously slow thermalization of strain-confined paraexcitons is observed.
    Tretyakov, Y.D., Komarov, V.F., Prosvirnina, N.A., and Kutsenok, I.B.
    Nonstoichiometry and Defect Structures in Copper Oxides and Ferrites 1972 Journal of Solid State Chemistry
    Vol. 5, pp. 157-167 
    article DOI  
    Abstract: The stoichiometry ranges of Cu2O1 + γ, CuO1 + γ, Cu0.984Fe2.016O4 + γ, Cu1.011Fe1.989O4 + γ, and Cu0.551Fe2.449O4 + γ were established by high temperature electrochemical measurements in a stabilized zirconia electrolyte cell. The results were consistent with neutral oxygen vacancies for oxygen deficit and neutral cation vacancies for oxygen excess in cuprite, neutral oxygen vacancies in Cu1.011Fe1.989O4 + γ and Cu0.551Fe2.449O4 + γ, neutral cation vacancies in Cu0.984Fe2.016O4 + γ and neutral associations of interstitial copper atoms in cupric oxide. The defect structures of these compounds were derived from the consideration of equilibrium with respect to oxygen between the solid and the gas phase. The absolute magnitudes of nonstoichiometry, defect concentrations and the enthalpy of defect formation were calculated. The enthalpies of the formation of Schottky defects in “Cu2O” and “CuFe2O4” were calculated.
    Trivich, D.
    Vol. 53, pp. 300-314 
    article URL 
    Trivich, D. and Pollack, G.P.
    Preparation of Single Crystals of Cuprous Oxide in an Arc--Image Furnace 1970 Journal of the Electrochemical Society
    Vol. 117, pp. 344-345 
    article DOI  
    Abstract: A crucible-free technique for pulling single-crystal cuprous oxide from the melt has been developed, involving the use of an arc-image furnace to form a melt on the top of a cylindrical ingot of cuprous oxide. Single crystals approximately 1 cm in diameter and 3.5 cm long were grown along [111], [110], and [111] directions by the use of oriented seeds. The crystals were found to cleave preferentially along (111) planes. A count of chemical etch pits on (111) faces indicates a dislocation density of 104 to 105 cm−2.
    Trivich, D., Wang, E.Y., Komp, R.J., and Ho, F.
    Cuprous Oxide Schottky Barrier Photovoltaic Cells 1976 Proceedings of 12th IEEE PhotoVoltaic Specialists Conference, Baton Rouge, LA, USA, pp. 875-878  inproceedings  
    Abstract: cu20 celle could be of importance in solar energy
    conversion because of the low cost and high availability
    The Cu20 is pre- of the mater3 and simple processing.
    pared by oxidation of copper sheet in air and the junctions

    OIL Cu20 are prepared by vacuum deposition of various
    metals. Typical values for current cells are J,, = 4 to 7
    mA/cm2, ” = 0.3” and fill factors of 0.35 with cm-
    version effi%endes approaching 1%. Calculations show
    that efficiencies of 6 to 12% are possible. A thermionic
    emission model is proposed.

    Trivich, D.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (fourth quaterly report) 1976 (NSF-AER-75-23453-4)  techreport  
    Trivich, D.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (fifth quaterly report) 1976 (NSF-AER-75-23453-5)  techreport  
    Trivich, D., Wang, E.Y., Komp, R.J., and Kakar, A.S.
    Cuprous oxide photovoltaic cells 1978 Proceedings of 13th IEEE PhotoVoltaic Specialists Conference, pp. 174-179  inproceedings  
    Abstract: cuprous oxide, with a hand gap Of 2.0 e”, is
    an attractive material for Solar cells because Of
    low cast and great availability. ‘Ihe CUrrent con-
    version efficiency is 1$, hut theoretical estimates
    are >13%. For various schottky barriers, e.g.,
    A1,C”*O, it is proposed that the voc is limited by
    chemical conversion of the junctions to Cu/Cuy3
    junctions, and the model is supported by auger and
    ESCA results. It is proposed to avoid. the reaction
    by use Of an oxide interlayer as in A1,A1~O~,C”ZO,
    which also gives an MIS structure, but only minimal
    S”CCBSS ha5 yet been achieved with the methods
    tried. Sh& and Sic& layers were explored.
    Another approach could be to use oxide tetero-
    junctions on Cup. Several were explored and mm/
    cuzo was best. In and Cd are effective dopantS for
    C”@. With samples annealed at 5oov. diffusion
    lengths Of -4 Lull were measured by an SP” method.
    The spectra1 sensitivity Of C”,CUZO cells has a
    threshold at 630 nm and a maximum at 500 nm.
    Trivich, D., Wang, E.Y., and Komp, R.J.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (first quarterly report) 1979 (DOE/ET/23010-T1)  techreport  
    Trivich, D. and Papadimitriou, L.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (second quarterly report) 1979 (DOE/ET/23010-9)  techreport  
    Trivich, D.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (third quarterly report) 1980 (DOE/ET/23010-12)  techreport  
    Trivich, D.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (fourth quarterly report) 1980 (DOE/ET/23010-17)  techreport  
    Trivich, D., Rakhshani, A.E., and Bazzi, A.
    Measurement of minority carrier diffusion length in cuprous oxide 1981 Proceedings of 15th IEEE Photovoltaic Specialists Conference, Kissimmee, FL, USA, pp. 1199-1201  inproceedings  
    Abstract: Electron diffLlSicxl lengths, h, in cu*o
    schottky barrier cells were measured by relating
    the photocurrent, I,, to the depletion width, w,
    under various reverse biases, v,. The values of 41
    were obtained as intercepts at I, = 0 Of linear
    plots of I, vs. w, using a wavelength of 600 "Ia.
    The values Of 41 were 0.1 fO 1.6 p for CU/C",O
    junctions with various doped samples of Cu20.
    capacitance measureme"t8 were used to determine
    the dielectric constant and W. Plots of Cb2 VS.
    VR, which were linear, were used to obtain the
    built-in potential, yielding values of 0.1 to 0.45
    Trivich, D.
    CUPROUS OXIDE PHOTOVOLTAIC CELLS (final report) 1981 (DOE/ET/23010-T10)  techreport  
    Trivich, D., Fish, D.L., and Iwanowski, R.J.
    Cu/Cu2O cells prepared by hydrogen bombardment 1982 Proceedings of the 16th IEEE Photovoltaic Specialists Conference, pp. 1072-1077  inproceedings  
    Abstract: A new method for preparing C"fCu20
    cells involves bombardment of Cu2O by a
    beam of hydrogen ions. The cells have
    V,C up to 0.72 V, compared with 0.35 V
    for cells made by thermal evaporation
    of C" on cu20. Auger studies show that
    the hydrogen bombardment reduces the
    top surface of the Cu20 to Cu, creating
    the Cu/Cu20 junction. The optimum pro-
    cessing conditions are bombardment at
    250 V for 75s at 15 mA. The surface
    resistivity of the C" film decreases
    with bombardment time, but 75s gives
    adequate continuity in the film.
    Electron diffraction shows the Cu is
    formed epitaxially on the Cu20. Encap-
    sulated cells are relatively stable.
    The conversion efficiency has reached
    1.3% for 1 cm2 cells.
    Trivich, D.
    Tsai, T.-L., Töpfer, J., Aggarwal, S., Chen, E., and Dieckmann, R.
    Cation Tracer Diffusion in Oxides 1996 Defect and Diffusion Forum
    Vol. 143-147, pp. 1183-1188 
    inproceedings DOI  
    Tselepis, E., Fortin, E., and Mysyrowicz, A.
    Exciton-Mediated Photovoltaic Effect in Cu2O/Cu 1987 Physical Review Letters
    Vol. 59, pp. 2107-2110 
    article DOI  
    Abstract: Low-temperature photovoltaic spectra in Cu2O/Cu are attributed to the diffusion of n=1 excitons and their subsequent dissociation at the metal-semiconductor interface.
    Tselepis, E. and Fortin, E.
    Photovoltaic study of anodically grown oxide films on Ag--Cu alloys 1988 Thin Solid Films
    Vol. 161, pp. 207-212 
    article DOI  
    Abstract: Semiconducting oxide films grown by anodic oxidation on Ag---Cu alloys were studied by using the photovoltaic effect at the oxide film-metallic substrate interface. Single-phase metallic alloys yielded single-phase oxides, while samples of two or three Ag---Cu metallic phases yielded more than one oxide phase. The composition and stability of the semiconducting oxide films were influenced by the nature of the oxidizing solution as much as by the composition of the metallic alloy they were grown from, as evidenced by the energy gaps measured from the photovoltaic spectra and the X-ray powder diffraction analysis.
    Tsui, S., Baikalov, A., Cmaidalka, J., Sun, Y.Y., Wang, Y.Q., Xue, Y.Y., Chu, C.W., Chen, L., and Jacobson, A.J.
    Field-induced resistive switching in metal-oxide interfaces 2004 Applied Physics Letters
    Vol. 85(2), pp. 317-319 
    article DOI  
    Abstract: We investigate the polarity-dependent field-induced resistive switching phenomenon driven by electric pulses in perovskite oxides. Our data show that the switching is a common occurrence restricted to an interfacial layer between a deposited metal electrode and the oxide. We determine through impedance spectroscopy that the interfacial layer is no thicker than 10 nm and that the switch is accompanied by a small capacitance increase associated with charge accumulation. Based on interfacial I–V characterization and measurement of the temperature dependence of the resistance, we propose that a field-created crystalline defect mechanism, which is controllable for devices, drives the switch.
    Tsur, Y. and Riess, I.
    Electrical Conductivity of Co Doped Cuprous Oxide 1995 Ionics
    Vol. 1, pp. 488-490 
    article DOI  
    Abstract: The solubility limit of metals in cuprous oxide is very low and it is therefore difficult to form solid solutions of metal oxides with cuprous oxide. In an on going research looking for such solid solutions and their properties we have prepared Co doped Cu2O. We report here on measurements of the electrical conductivity of Co doped Cu2O as a function of the oxygen partial pressure. It is found that Co doped material is an n-type semiconductor in the low oxygen partial pressure regime and p-type at higher oxygen pressures (while undoped Cu2O is a p-type material throughout the whole existence regime). A point defect model is discussed. The ionic transference number is also measured and is found to be less than 2⋅10−4.
    Tsur, Y. and Riess, I.
    Impurity Solubility Limits in Ionic Crystals, with Application to Cu2O 1998 Zeitschrift für Physikalische Chemie
    Vol. 207, pp. 181-213 
    Abstract: We have examined the possibility to dope, in particular Cu2O, with a series of aliovalent and isovalent ions. Detailed measurements were done on Ag and Co doping. Other ions considered were: Li+, Na+, K+, Ni2+, Bi3+, and Wi+, (i=4 or 6). The solubilities found were low, usally below ~0.1%cation, except for Ag+ which dissolved with 2%cation.
    An analysis is presented that allows calculating the solubilty limits. The concepts of "corresponding native defects" of the host material is introduced. With a knowledge of the concentration of the "corresponding native defects", the standard chemical potential of the materials involved and the shear modulus of the host material, one can calculate the solubilities of the impurities.
    Using the results of that analysis to fit the experimental data the shear modulus of Cu2O is determined to be 1.7∙1011 N/m2 , a value obtained from consideration of the strain on a microscopic atomic scale.
    Tsur, Y. and Riess, I.
    Doping of ionic compounds: solubility limit and self--compensation 1999 Solid State Ionics
    Vol. 119, pp. 37-42 
    article DOI  
    Abstract: An analysis is presented that allows calculating properties of primary solid solutions in ionic crystals. These properties are expressed in terms of properties of the undoped host material and the impurity. One can calculate the solubilities of the impurities with a knowledge of the concentration of the ‘corresponding native defects’, the standard chemical potential of the materials involved and the shear modulus of the host material. The changes in concentrations of ionic point defects as well as electron/hole concentrations due to doping are also calculated. In order to do so one has to know the concentrations of the native point defects in the undoped host material and the concentration of the dopant. It is shown that in a native p-type semiconductor (e.g. Cu2O) donors are mainly self-compensated by ionic defects, while acceptors are compensated significantly by holes.
    Tsur, Y. and Riess, I.
    Self--compensation in semiconductors 1999 Physical Review B
    Vol. 60, pp. 8138-8146 
    article DOI  
    Abstract: The problem of self-compensation of charged dopants is analyzed. Special emphasis is given to dopants in binary oxides. It is shown that one can determine the degree of self-compensation from the properties of the host material and dopant concentration alone. It is further shown that for a native p-type semiconductor, donors are compensated, mostly, by native ionic defects. On the other hand, doping with acceptors allows us to increase significantly the hole concentration, i.e., self-compensation is low under high doping levels. For a native n-type semiconductor the opposite is true, namely, extrinsic acceptors are mainly compensated by native ionic defects. It is shown that the changes in concentration of all the charged defects are simply related by a single factor, the doping factor f, or its power fk where k depends solely on the defect’s charge. Quantitative calculations of f and defect concentrations are presented for Cu2O, which was used as a model material. It is found that for p-type Cu2O doping with donors results in f within the range of 1–10, depending on the dopant concentration and P(O2). This means that the hole concentration decreases and the electron concentration increases at most by a factor of 10. Therefore one does not expect to obtain a changeover from p- to n-type cuprous oxide by doping, under equilibrium conditions. Most of the donors are compensated by negative ionic defects. Self-compensation in the presence of amphoteric defects and Fermi level stabilization are discussed, using the former formalism.
    Tylecote, R.F.
    Vol. 53, pp. 191-197 
    Ueno, T.
    On the Contour of the Absorption Lines in Cu2O 1969 Journal of the Physical Society of Japan
    Vol. 26(2), pp. 438-446 
    article DOI  
    Abstract: The contour of the absorption spectrum in Cu2O has been measured at various temperatures between 4.2°K and 298°K. The broadenings and the asymmetries of the absorption lines have been analyzed on the basis of Toyozawa's theory on the general problem of the exciton-phonon interaction: Half-value widths of the yellow- and green-series absorption lines are proportional to temperature above about 80°K. The asymmetries of the yellow-series absorption lines increase as temperature rises, while those of the green-series lines are nearly constant. The observed contours of the yellow-series absorption lines agree with the asymmetric Lorentzian fairly well. On the contrary, the green-series n=2 line observed at various temperatures deviates slightly from the asymmetric Lorentzian on the high energy side of the peak position. The origin of the line broadening with asymmetry is discussed in terms of the interband exciton scattering by phonons.
    Uihlein, C., Fröhlich, D., and Kenklies, R.
    Investigation of exciton fine structure in Cu2O 1981 Physical Review B
    Vol. 23, pp. 2731-2740 
    article DOI  
    Abstract: The even-parity excitons in Cu2O show, in contrast to the well known P-exciton series: (1) strong deviations from a hydrogenlike behavior, (2) a fine structure for n≥3, and (3) an unusual n dependence of the exchange splitting. All the properties of the even-parity-exciton series are explained by the presence of a strong Hd term and a strong exchange interaction. We have calculated the even- and odd-exciton members of the yellow and green series within the formalism of Baldereschi and Lipari. An excellent agreement with the experimental results is obtained in the spherical limit. The theory predicts for n=3 a splitting of the S and D states into five components. All the five components are observed by two-photon absorption in a magnetic field of 7 T.
    Uno, R. and Okada, T.
    On the Thermal Expansion of Cuprous Oxide 1950 Journal of the Physical Society of Japan
    Vol. 5(1), pp. 23-25 
    article DOI  
    Vajda, P.
    Radiation Annealing in Cuprous Oxide 1966 Physica Status Solidi (b)
    Vol. 14(2), pp. 287-290 
    article DOI  
    Abstract: Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser [3] statistical model of radiation annealing, giving a square-root relationship between the rate of change of resistivity and the resistivity change. The saturation defect density at room temperature is estimated on the basis of a model for defect creation in cuprous oxide.
    Vattuone, L., Savio, L., Gerbi, A., Okada, M., Moritani, K., and Rocca, M.
    High-resolution Electron Energy Loss Spectroscopy Study of O-Cu$(410)$ 2007 The Journal of Physical Chemistry B
    Vol. 111(7), pp. 1679-1683 
    article DOI  
    Abstract: We have investigated oxygen adsorption on Cu(410) by high-resolution electron energy loss spectroscopy, dosing O2 with a supersonic molecular beam at different surface temperatures and for different angles of incidence and beam energies or by backfilling. In the investigated crystal temperature range (127 < T < 570 K), adsorption is always dissociative. Depending on T, impact energy, and angle of incidence, the oxygen atoms end up in different adsorption configurations, characterized by different vibrational signatures. In particular, at grazing incidence when only the step edge is exposed to O2, the adatoms end up initially preferentially at the step edge. An ordered overlayer forms at half monolayer coverage when the adsorbate is mobile. Oxide patches develop eventually for large exposures performed by backfilling and at high crystal temperature.
    Vertegel, A.A., Shumsky, M.G., and Switzer, J.A.
    Electrochemical Growth of a Cu2O/PbS Epitaxial Heterojunction on Single Crystal Au$(100)$ 2000 Chemistry of Materials
    Vol. 12(3), pp. 596-598 
    article DOI  
    Abstract: Schematic of the Cu2O/PbS semiconductor heterojunction on Au (100) showing the epitaxial relations between the layers. The 0.5-mum-thick PbS and Cu2O films were consecutively electrodeposited onto a Au(100) single crystal at room temperature. Both layers showed a strong (100) out-of-plane texture. Azimuthal X-ray diffraction studies of the in-plane relationships revealed that the PbS structure is rotated 45o relative to the substrate, while the Cu2O overlayer shows no rotation with respect to Au.
    Wadia, C., Alivisatos, A.P., and Kammen, D.M.
    Materials Availability Expands the Opportunity for Large-Scale Photovoltaics Deployment 2009 Environmental Science & Technologies
    Vol. 43, pp. 2072-2077 
    article DOI  
    Abstract: Solar photovoltaics have great promise for a low-carbon future but remain expensive relative to other technologies. Greatly increased penetration of photovoltaics into global energy markets requires an expansion in attention from designs of high-performance to those that can deliver significantly lower cost per kilowatt-hour. To evaluate a new set of technical and economic performance targets, we examine material extraction costs and supply constraints for 23 promising semiconducting materials. Twelve composite materials systems were found to have the capacity to meet or exceed the annual worldwide electricity consumption of 17000 TWh, of which nine have the potential for a significant cost reduction over crystalline silicon. We identify a large material extraction cost (cents/watt) gap between leading thin film materials and a number of unconventional solar cell candidates including FeS2, CuO, and Zn3P2. We find that devices performing below 10% power conversion efficiencies deliver the same lifetime energy output as those above 20% when a 3/4 material reduction is achieved. Here, we develop a roadmap emphasizing low-cost alternatives that could become a dominant new approach for photovoltaics research and deployment.
    Wagner, C. and Hammen, H.
    1938 Zeitschrift für Physikalische Chemie
    Vol. B40, pp. 197 
    Wagner, C.
    Equations for transport in solid oxides and sulfides of transition metals 1975 Progress in Solid State Chemistry
    Vol. 10(Part 1), pp. 3-16 
    article DOI  
    Walker, A.V. and Yates, J.T.
    Does Cuprous Oxide Photosplit Water? 2000 The Journal of Physical Chemistry B
    Vol. 104(38), pp. 9038-9043 
    article DOI  
    Abstract: A thin film of copper(I) oxide (thickness 9 A), grown on a Cu(111) crystal, was used as a model photocatalyst for decomposition of D2O using ultraviolet light (hnu = 1.556.21 eV). No evidence for water photosplitting was observed. The experimental uncertainties establish an upper limit of 2 10-21 cm2 for the cross section of the photoprocess sought. The pure Cu2O film was grown by bombardment with O2+ ions (1.5 kV) at a sample temperature of 605 K and was characterized by Auger electron spectroscopy.
    Wang, E.Y., Trivich, D., Komp, R.J., Huang, T.-F., and Brinker, D.J.
    Cuprous Oxide MIS solar cells 1980 Proocedings of the 14th IEEE Photovoltaic Specialists Conference, pp. 458-461  inproceedings  
    Abstract: Cuprous oxide MIS solar cells were made with
    SiO interfacial layers of thickness ranging from
    10 $0 100 A, and semi-transparent layers of Au,
    Cu, Ag and Al. Results from current-voltage
    measurements show that Au/SiO /Cu 0 MIS devices
    are ohmic in nature and have o I) otovoltaic ef- 6 a
    feet. Ag/SiO /Cu 0, Cu/SiO fCu2b and
    A1/SiOz/Cu20,??xhi&t rectifying and photovoltaic
    charac enstlcs. Capacitance-voltage measure-
    ments indicate that the space charge region is
    approximately .5 urn wide. The wavelength depen-
    dence of the open-circuit photovoltage has a peak
    at 2.56 eV which can be correlated with reported
    Cu20 absorption coefficients.
    Wang, W., Varghese, O., Ruan, C., Paulose, M., and Grimes, C.
    Synthesis of CuO and Cu2O crystalline nanowires using Cu(OH)2 nanowire templates 2003 Journal of Materials Research
    Vol. 18, pp. 2756-2759 
    article DOI  
    Abstract: One-dimensional (1D) nanoscale materials are currently of great interest due to their unique electronic, optical, and mechanical properties.1-7 Consequently, many 1D nanostructures such as carbon nanotubes,8-10 as well as inorganic nanowires/rods11-17 and nanotubes,18-21 have been synthesized through a variety of methods. Other recent efforts have focused on the synthesis of 1D nanoscale oxide architectures, see for example.22 Our interest lies in application of copper oxide nanostructures to achieve high-performance gas sensors; however, there are few published reports on routes for fabrication of 1D copper oxide nanostructures. In our previous work,23 we synthesized pure Cu2O nanowires using a wet chemical method in which the surfactant poly(ethylene glycol) (Mw 20 000) was used as a soft template. Recently it has been reported that a mixture of CuO and Cu2O nanowires, having a range of diameters from 30 nm to 100 nm, can be fabricated by heating a copper substrate in air.24 In this communication, we report on a novel fabrication route, which requires neither sophisticated techniques nor catalysts and surfactants, to selectively prepare two distinct wirelike copper oxides, either CuO or Cu2O depending on the synthesis conditions, with an average wire diameter of approximately 10 nm. The synthesis strategy for CuO and Cu2O nanowire fabrication starts with a sequence of reactions to first fabricate precursor Cu(OH)2 nanowires. The precursor polycrystalline nanowires are used both as reactants for the growth of CuO and Cu2O nanowires and as templates controlling the size and shape of the resulting nanowires.
    Wang, Y., Cao, Y., Wang, M., Zhong, S., Zhang, M.-Z., Feng, Y., Peng, R.-W., Hao, X.-P., and Ming, N.-B.
    Spontaneous formation of periodic nanostructured film by electrodeposition: Experimental observations and modeling 2004 Physical Review E
    Vol. 69(2), pp. 021607 
    article DOI  
    Abstract: In this paper we report the spontaneous formation of a nanostructured film by electrodeposition from an ultrathin electrolyte layer of CuSO4. The film consists of straight periodic ditches and ridges, which corresponds to the alternating deposition of nanocrystallites of copper and copper plus cuprous oxide, respectively. The periodicity on the film may vary from 100 nm to a few hundred nanometers depending on the experimental conditions. In the formation of the periodically nanostructured film, oscillating voltage/current has been observed across the electrodes, and the frequency depends on the pH of the electrolyte and the applied current/voltage. A model based on the coupling of [Cu2+] and [H+] in the electrodeposition is proposed to describe the oscillatory phenomena in our system. The calculated results are in agreement with the experimental observations.
    Wang, L. and Yang, J.C.
    Enhanced nucleation and decreased growth rates of Cu2O in Cu$_0.5$Au$_0.5$ $(001)$ thin films during in situ oxidation 2005 Journal of Materials Research
    Vol. 20(7), pp. 1902-1909 
    article DOI  
    Abstract: The initial oxidation behaviors of Cu–50 at.% Au (001) single-crystal thin film were studied by in situ ultra-high-vacuum transmission electron microscopy to model nano-oxidation of alloys with one oxidizing component and one inert component. The oxidation behaviors such as incubation time, oxide nucleation rate, oxide growth kinetics as well as nucleation activation energy were greatly changed by the addition of nonoxidizing Au. The reasons for these changes, such as Au segregation to the top surface, a decrease in Cu activity, and reduced lattice mismatch due to the addition of Au, were discussed, and a qualitative analysis of nucleation energetics was given.
    Wang, J.Y., Odom, T.W., Barton, J.E., and Stender, C.L.
    Growth of Cu2O Nanocubes from Seeds in Microwells 2005 Nanoscape
    Vol. 2(1), pp. 57-65 
    article URL 
    Abstract: This project focused on the growth of Cu2O
    nanocubes in microwells from nanoparticle
    “seeds.” The seeds were first formed by the
    reduction of copper sulfate with ascorbic
    acid in the presence of the surfactant
    poly(ethylene glycol) (PEG). Upon reaction
    within the microwell, the seed solution
    formed a larger single crystal. By varying
    the amount of precursor seed particles
    available in the reaction, nanocubes of
    different sizes were formed. The surfactant
    was removed from the surface of the
    nanocubes using ethanol. The nanocubes
    were characterized by atomic force
    microscopy (AFM) and scanning electron
    microscopy (SEM).
    Wang, L.C., de Tacconi, N.R., Chenthamarakshan, C.R., Rajeshwar, K., and Tao, M.
    Electrodeposited copper oxide films: Effect of bath pH on grain orientation and orientation-dependent interfacial behavior 2007 Thin Solid Films
    Vol. 515(5), pp. 3090-3095 
    article DOI  
    Abstract: Copper (I) oxide (Cu2O) films were cathodically electrodeposited on Sn-doped indium oxide substrates. The influence of electrodeposition bath pH on grain orientation and crystallite shape was carefully re-examined using X-ray diffraction and scanning electron microscopy. In addition to the (100) and (111) preferred orientations identified in two previous sets of studies, as the bath pH was varied in the present study from ~ 7.5 to ~ 12, a third preferred orientation, (110), was identified in a narrow pH range, ~ 9.4 to ~ 9.9. A remarkable shift in the flat-band potential (spanning ~ 500 mV) was measured in a non-aqueous electrolyte medium for the various Cu2O samples obtained from baths of varying pH.
    Wang, L. and Tao, M.
    Fabrication and Characterization of p-n Homojunctions in Cuprous Oxide by Electrochemical Deposition 2007 Electrochemical and Solid-State Letters
    Vol. 10(9), pp. H248-H250 
    article DOI  
    Abstract: The conduction type (n- or p-type) of electrochemically deposited cuprous oxide (Cu2O) can be controlled by solution pH. It was found that cuprous oxides deposited at solution pH below 7.5 are n-type semiconductors, while cuprous oxides deposited at a solution pH above 9.0 are p-type semiconductors. A two-step process was adopted to deposit p-type and n-type cuprous oxides in sequence for the formation of a p-n homojunction in cuprous oxide. Photocurrent and current-voltage measurements demonstrate the successful formation of a p-n homojunction of cuprous oxide.
    Wang, L., Han, K., and Tao, M.
    Effect of Substrate Etching on Electrical Properties of Electrochemically Deposited CuO 2007 Journal of the Electrochemical Society
    Vol. 154(2), pp. D91-D94 
    article DOI  
    Abstract: The effect of Cu substrate etching on electrical properties of electrochemically deposited CuO was investigated. Four different etching methods were compared in this study—no etching, chemically etched in HNO3, ex situ electrochemically etched in H2SO4, and in situ electrochemically etched in the deposition solution. Surface roughness by atomic force microscopy was used to optimize the electrochemical etching processes. Metal/CuO diodes were fabricated by depositing various metals on Al, Ni, and Cu. Current-voltage characterization was performed to investigate the electrical properties of the as-deposited CuO films. CuO grown on electrochemically etched Cu substrates had favorable electrical properties over chemical etched and nonetched substrates as evidenced by better rectification behavior and lower current through the CuO films. Al/CuO diodes showed rectifying behavior, while Ni/CuO and Cu/CuO diodes both showed ohmic behavior. Transmittance measurements of as-deposited CuO showed that CuO has an indirect bandgap of 1.32 eV. Scanning electron microscopy revealed that CuO deposited at above 50°C was polycrystalline, while amorphous below 50°C.
    Wang, Z., Wang, H., Wang, L., and Pan, L.
    Controlled synthesis of Cu2O cubic and octahedral nano- and microcrystals 2009 Crystal Research and Technology
    Vol. 44(6), pp. 624-628 
    article DOI  
    Abstract: Cubic and octahedral Cu2O nano- and microcrystals were selectively synthesized via a simple wet chemical reduction route at room temperature, with CuCl2 and NaOH as starting reactants, and ascorbic acid or hydrazine hydrate as the reducer. Hydrazine hydrate could be preferentially adsorbed on different crystal faces of Cu2O, affecting the growth rate along the <100> to that along the <111> direction, which resulted in the formation of octahedral Cu2O crystals. When ascorbic acid was used as the reducer, the growth rate along the <100> to that along the <111> direction was different, which resulted in the formation of cubic Cu2O crystals. The size of cubic and octahedral Cu2O crystals could be varied by adjusting the molar ratio of OH� to Cu2+.
    Wang, Y., Liang, W., Satti, A., and Nikitin, K.
    Fabrication and microstructure of Cu2O nanocubes 2010 Journal of Crystal Growth
    Vol. 312(9), pp. 1605-1609 
    article DOI  
    Abstract: Cu2O nanocubes (edge length of 6 to 250�nm) have been produced by annealing a copper grid at 300��C in air with the presence of tetraoctylammonium bromide (TOAB)-stabilized gold nanoparticles. The microstructure of the nanocubes has been investigated in details using conventional and high-resolution transmission electron microscopy (HRTEM), and chemical analysis has been performed using energy dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscopy (STEM). Based on the experimental results, a possible growth mechanism is proposed.
    Warren, S., Flavell, W.R., Thomas, A.G., Hollingworth, J., Dunwoody, P.M., Downes, S., and Chen, C.
    Adsorption of H2O on single crystal CuO 1999 Surface Science
    Vol. 436(1-3), pp. 1-8 
    article DOI  
    Abstract: The adsorption of water on a cleaved single crystal of CuO has been studied. Photoemission was used to record the changes in the valence band region on dosing. With a 10 L exposure to the surface at 128 K, the interaction was found to be non-dissociative. There is some evidence for the formation of multilayers on the CuO crystal at these low temperatures. As the temperature of the CuO sample increases, the H2O dissociates leaving OH on the surface. A comparison is made with the literature, particularly for the adsorption of water on semiconducting oxides and cuprate superconductors.
    Warren, J.T., O'Hara, K.E., and Wolfe, J.P.
    Two-body decay of thermalized excitons in Cu2O 2000 Physical Review B
    Vol. 61, pp. 8215-8223 
    article DOI  
    Abstract: We have examined the decay of thermalized excitons in cuprous oxide (Cu2O) and determined their lifetime against two-body decay (i.e., Auger recombination). The experiments are conducted at T=70 K with near-resonant picosecond excitation to ensure a thermal equilibrium between orthoexcitons, paraexcitons, and the crystal lattice. Time-resolved spectroscopy reveals the gas reaching equilibrium with the lattice temperature in 0.5 ns. The wavelength of the excitation photons and the spatial distribution of the laser beam are selected to produce a well defined spatial distribution of excitons. Time-resolved photoluminescence imaging measures the diffusion of excitons. From absolute measurements of the gas volume and the luminescence intensity, we determine the instantaneous gas density. At high excitation levels, a rapid nonexponential decay of the excitonic gas is observed. The decay curve is well explained by assuming that the local exciton density is governed by the rate equation dn/dt=-An2-n/τ, with an Auger constant A=0.6×10-16 cm3/ns and a residual decay time τ=300 ns. This value of the Auger constant is comparable to that estimated previously for a nonthermalized exciton gas at a lattice temperature of 2 K, indicating that the Auger lifetime of an exciton is only weakly dependent on its kinetic energy. The Auger process characterized here defines the practical limits for exciton densities in cuprous oxide.

    Cuprite --- Webmineral 2010   misc URL 
    Wei, M., Braddon, N., Zhi, D., Midgley, P.A., Chen, S.K., Blamire, M.G., and MacManus-Driscoll, J.L.
    Room temperature ferromagnetism in bulk Mn-doped Cu2O 2005 Applied Physics Letters
    Vol. 86, pp. 072514 
    article DOI  
    Abstract: Bulk Mn-doped Cu2O samples were produced by reacting Cu2O and Mn2O3 powders in Ar gas at 650 and 800 °C to give a nominal composition of 1.7 at.% Mn-doped Cu2O. From x-ray energy dispersive spectrum analysis, the actual doping level was lower at 0.3–0.5 at.% Mn. Room temperature ferromagnetism with a coercive field of 50 Oe was found in the 650 °C samples. The Curie temperature (TC) of samples sintered at 650 °C was above 300 K, whereas for 800 °C samples it was 215±5 K. Using the nominal doping level, the magnetization saturation value was calculated to be ∼ 0.4μB/Mn at 10 K.
    Wei, M. and Huo, J.
    Preparation of Cu2O nanorods by a simple solvothermal method 2010 Materials Chemistry and Physics
    Vol. 121(1-2), pp. 291-294 
    article DOI  
    Abstract: Cuprous oxide nanorods had been synthesized via solvothermal treatment of CuSO4�5H2O and NaOH in the mixed solution of ethanol and deionized water at 140��C for 6-10�h, in which ethanol was used as a reducing agent, as well as a solvent. The as-prepared Cu2O nanorods were characterized by X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The results indicated that the nanorods were well crystallized and uniform in size. Cu2O nanorods with different aspect ratios were obtained by adjusting the ratio of ethanol and deionized water of the mixed solution. It was proposed that the reducibility of ethanol was influenced by the temperature and the amount of deionized water and it was improved at a higher temperature and less addition of deionized water.
    Weichman, F.L.
    Photoconductivity of Cuprous Oxide in Relation to Its Other Semiconducting Properties 1960 Physical Review
    Vol. 117(4), pp. 998-1002 
    article DOI  
    Abstract: It is shown that at least two of the three known peaks in the photoconductivity versus wavelength curve of Cu2O are strongly dependent on the oxygen content of the material. The peak near 600 mμ can be shifted from shorter to longer wavelengths by exposing the sample to relatively low oxygen pressures at 860°C. The peak near 800 mμ is found to increase in magnitude relative to the others under these circumstances. This is in apparent contrast to the results of previous investigators. It is further shown that both results are consistent with the values of the high temperature activation energy of the conductivity process, as well as with the change in bandgap as a function of temperature as obtained from optical absorption measurements under the assumption that Cu2O can be classified as a nonpolar semiconductor.
    Weichman, F.L. and McInnis, B.C.
    Vol. 43(4), pp. 507-522 
    article URL 
    Abstract: Measurements were made at a number of different wavelengths to find the temperature dependence of the photoconductivity in Cu2O of resistivity greater than 108 ohm-cm between +100 °C and −100 °C. A number of features of this temperature dependence are discussed with particular reference to making a-c. measurements on a slowly responding photoconductor. It is shown that as the chopping period becomes short in comparison with the response time of the photoconductor, the r.m.s. photoconductivity will decrease linearly with the chopping period for three different types of response considered. Photoresponse at room temperature was also measured on Cu2O after two methods of vacuum annealing, one at 1 000 °C and the other at 300 °C. The former shows a sensitivity only for wavelengths less than 0.6 μ, whereas the latter shows the more usual behavior of a peak near 0.6 μ, with sensitivity measurable well into the near infrared.
    Weichman, F.L. and Kužel, R.
    Grain-Boundary Conductivity of Cu2O Polycrystals and Rectifiers 1970 Journal of Applied Physics
    Vol. 41, pp. 3491-3498 
    article DOI  
    Abstract: The contribution to the electrical conductivity of grain boundaries in polycrystalline Cu2O was measured in vacuum and in air between 200° and −145°C. It was found to follow a simple exponential temperature dependence with a single activation energy of about 0.31 eV. Heat treatment at 200°C can be used to vary the contribution of the grain boundaries from 5×10−9 Ω−1 in air to 8×10−10 Ω−1 in vacuum at room temperature. The effects are explained by impurities conglomerating at the grain boundaries and the diffusion of oxygen along these boundaries. The deterioration of the volt‐ampere characteristics of cuprous oxide rectifiers after preparation or as a result of extensive heating above 150°C is explained by the same mechanism. The studies of the rectifiers were based on measurements on capacity and resistance of the barrier layers at room temperature.
    Weichman, F.L. and Chee, K.T.
    Pt-Cu2O-Cu single-carrier space-charge-limited diodes 1977 Canadian Journal of Physics
    Vol. 55(7-8), pp. 735-741 
    article URL 
    Abstract: This paper reports on the experimental results on the characteristics of the single-crystal Cu2O diodes, annealed at a pressure of 10−6 Torr at a temperature of 800 °C. In contrast to our previous report on oxidized samples which showed the characteristics of double injection diodes, these diodes exhibit the characteristics of single-carrier space-charge-limited (SCL) conduction. The conduction mechanism was confirmed by measurements on the I–V characteristics at various temperatures, the thickness vs. current relation at a given voltage, the effect of photomemory on the I–V characteristics, and the transient current response to applied voltage steps. The results also indicate that there are continuous levels of localized states in these samples in the range 0.06 eV to 0.47 eV above the valence band edge.
    Werner, A. and Hochheimer, H.D.
    High--Pressure X--ray study of Cu2O and Ag2O 1982 Physical Review B
    Vol. 25, pp. 5929-5934 
    article DOI  
    Abstract: Pressure-induced phase transitions have been found in Cu2O and Ag2O by high-pressure x-ray diffraction technique at room temperature. Cu2O transforms from the cuprite to a hexagonal structure at a pressure of 10 GPa. This hexagonal form changes in the pressure range from 13 to 18 GPa into another hexagonal form, with a CdCl2-type structure. Up to 24 GPa, the highest pressure generated, no decomposition of Cu2O into Cu and CuO was observed. Ag2O transforms at 0.4 GPa from the cuprite structure to a hexagonal structure which is identical with that found above 10 GPa in Cu2O. Extended p-T phase diagrams of Cu2O and Ag2O are presented using the results of the x-ray study and, in the case of Cu2O, additional results of an optical investigation.
    Whelan, C., Kinsella, M., Ho, H., and Maex, K.
    In-situ cleaning and passivation of oxidized Cu surfaces by alkanethiols and its application to wire bonding 2004 Journal of Electronic Materials
    Vol. 33(9), pp. 1005-1011 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp;The treatment of oxidized Cu surfaces using an alkanethiol as a reducing agent has been investigated. Exposure to a dilute solution of 1-decanethiol resulted in the complete removal and/or conversion of CuO and subsequent formation of a passivating thiolate film, a so-called self-assembled monolayer (SAM), on the underlying Cu/Cu2O surface as evidenced by x-ray photoelectron spectroscopy (XPS) analysis. Morphological changes, monitored by scanning electron microscopy (SEM) and atomic force microscopy (AFM), revealed transformation of the rough, porous CuO layer into a comparatively smooth Cu/Cu2O surface. Experiments performed on integrated circuit back-end-of-line (BEOL) die structures, comprising Cu/SiO2 bond pads used as substrates for Cu wire bonding, demonstrate the potential application of a thiol-based in-situ cleaning-passivation procedure in microelectronics.
    Widmer, R., Haug, F.-J., Ruffieux, P., Gröning, O., Bielmann, M., Gröning, P., and Fasel, R.
    Surface Chirality of CuO Thin Films 2006 Journal of the American Chemical Society
    Vol. 128(43), pp. 14103-14108 
    article DOI  
    Abstract: We present X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD) investigations of CuO thin films electrochemically deposited on an Au(001) single-crystal surface from a solution containing chiral tartaric acid (TA). The presence of enantiopure TA in the deposition process results in a homochiral CuO surface, as revealed by XPD. On the other hand, XPD patterns of films deposited with racemic tartaric acid or the “achiral” meso-tartaric acid are completely symmetric. A detailed analysis of the experimental data using single scattering cluster calculations reveals that the films grown with l(+)-TA exhibit a CuO(11̄1̄) orientation, whereas growth in the presence of d(−)-TA results in a CuO(1̄11) surface orientation. A simple bulk-truncated model structure with two terminating oxygen layers reproduces the experimental XPD data. Deposition with alternating enantiomers of tartaric acid leads to CuO films of alternating chirality. Enantiospecifity of the chiral CuO surfaces is demonstrated by further deposition of CuO from a solution containing racemic tartaric acid. The predeposited homochiral films exhibit selectivity toward the same enantiomeric deposition pathway.
    Wieder, H. and Czanderna, A.W.
    THE OXIDATION OF COPPER FILMS TO CuO$_0.67$ 1962 The Journal of Physical Chemistry
    Vol. 66(5), pp. 816-821 
    article DOI  
    Wieder, H. and Czanderna, A.W.
    Optical Properties of Copper Oxide Films 1966 Journal of Applied Physics
    Vol. 37(1), pp. 184-187 
    article DOI  
    Wijesundara, R.P., Perera, L.D.R.D., Jayasuriya, K.D., Siripala, W., De Silva, K.T.L., Samantilleke, A.P., and Dharmadasa, I.M.
    Sulphidation of electrodeposited cuprous oxide thin films for photovoltaic applications 2000 Solar Energy Materials and Solar Cells
    Vol. 61(3), pp. 277-286 
    article DOI  
    Abstract: Electrodeposited cuprous oxide thin films on indium-doped tin oxide (ITO) substrates were sulphided by exposing them to a spray of aqueous solution of sodium sulphide or to a mixture of hydrogen sulphide and nitrogen gases. Both methods produced light darker and darker films having different photovoltaic characteristics in a solar cell structure. The photovoltages produced by the light darker films under AM 1.5 illumination was negative as compared to the positive photovoltages produced by the darker films. Spectral response measurements revealed that most of the light darker films produced positive photovoltages in the shorter wavelengths and negative photovoltages in the longer wavelengths. However, some of the light darker films produced only the negative photovoltage for the entire spectral range and their photovoltaic properties were comparatively better. Darker films resulted in only the positive photovoltages in the entire spectral range. As a result of the sulphidation, the bulk crystal structure of the cuprous oxide thin films was not changed, however, the interfacial characteristics of the solar cell structure were modified.
    Wijesundera, R.P., Hidaka, M., Koga, K., Sakai, M., and Siripala, W.
    Growth and characterisation of potentiostatically electrodeposited Cu2O and Cu thin films 2006 Thin Solid Films
    Vol. 500(1-2), pp. 241-246 
    article DOI  
    Abstract: Cuprous oxide and copper thin films were potentiostatically electrodeposited in an acetate bath. Voltammetric curves were used to investigate the growth parameters; deposition potential, pH and temperature of the bath. Deposition potential dependency on the structural, morphological, optical and electronic properties of the films were investigated by the X-ray diffraction measurements, scanning electron micrographs, absorption measurements and dark and light current-voltage characterisations. It was observed that single phase polycrystalline Cu2O can be deposited from 0 to - 300 mV Vs saturated calomel electrode (SCE) and co-deposition of Cu and Cu2O starts at - 400 mV Vs SCE. Further increase in deposition potential from - 700 mV Vs SCE produces single phase Cu thin films. Single phase polycrystalline Cu2O thin films with cubic grains of 1-2 [mu]m can be possible within the very narrow potential domain around - 200 mV Vs SCE. Enhanced photoresponse in a photoelectrochemical cell is produced by the Cu2O thin film prepared at - 400 mV Vs SCE, where Cu is co-deposited with Cu2O with random distribution of Cu spheres on the Cu2O surface. This study reveals that a single deposition bath can be used to deposit both Cu and Cu2O separately and an admixture of Cu-Cu2O by controlling the deposition parameters.
    Wijesundera, R.P., Hidaka, M., Siripala, W., Choi, S.-H., Sung, N.E., Kim, M.G., and Lee, J.M.
    Electronic states and local structures of Cu ions in electrodeposited thin films of Cu and Cu2O from X-ray absorption spectra 2006 Physica Status Solidi (b)
    Vol. 243(8), pp. 1791-1801 
    article DOI  
    Abstract: X-ray absorption spectra near Cu K edges have been obtained for Cu and Cu2O thin films potentiostatically electrodeposited in an acetate bath. The electronic states of Cu ions and the local structures around these ions are studied using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively. The inner strains in micro-size crystals of the electrodeposited Cu thin film are less than those of a commercial Cu foil. The partial electronic states of Cu ions near the Fermi level (E F) and the local structure around these ions show a systematic transformation from a Cu2O single phase (Phase I), to a Cu2O-Cu intermediate phase (Phase II) and a Cu single phase (Phase III) in thin films electrodeposited on titanium substrates for the deposition potential range of -100 to -900 mV. Phase II consists of independent Cu2O-like and Cu-like local structures, but not a Cu2O-Cu complex. Phase II is also characterized by a transition region from the semiconductor Cu2O to the metal Cu for the Cu electronic state having a p-like character near the Fermi level in the oxygen O-2p conduction band. (� 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

    Copper(I) oxide --- Wikipedia, The Free Encyclopedia 2010   misc URL 

    Copper(II) oxide --- Wikipedia: The Free Encyclopedia 2010   misc URL 

    Cuprite --- Wikipedia: The Free Encyclopedia 2010   misc URL 
    Wilhelm, S.M., Tanizawa, Y., Liu, C.-Y., and Hackerman, N.
    A photo-electrochemical investigation of semiconducting oxide films on copper 1982 Corrosion Science
    Vol. 22(8), pp. 791-805 
    article DOI  
    Abstract: p-type copper oxides formed by electrochemical and chemical methods are compared using voltammetry and photo-electrochemical techniques. Cupric and cuprous films exhibit characteristic photo-current signals, the sign and magnitude of which are a function of band curvature. Semi-conductor properties and aspects of the band structure of the surface films have been determined from observations of the spectral dependence of photo-assisted charge transfer. The positions of voltammetry peaks and the standard potentials of oxide formation are correlated with the flat band potentials of Cu2O and CuO. The inhibition of copper oxidation by illumination and the corrosion of copper in solutions containing O2 are discussed with regard to derived semiconductor models.
    Williams, P.F. and Porto, S.P.S.
    Symmetry-Forbidden Resonant Raman Scattering in Cu2O 1973 Physical Review B
    Vol. 8(4), pp. 1782-1785 
    article DOI  
    Abstract: We have observed resonant Raman scattering from the two longitudinal branches of the Raman-forbidden F1u modes of Cu2O. The agreement between our measured scattering cross section as a function of excitation frequency and a calculated cross section which assumes an intraband Fröhlich electron-phonon interaction is good. This represents a quantitative confirmation of the resonant-Raman-scattering theory proposed by Martin.
    Wolfe, J.P.
    Imaging of excitonic transport in semiconductors 1992 Journal of Luminescence
    Vol. 53(1-6), pp. 327-334 
    article DOI  
    Abstract: Excitonic matter produced by photoexcitation of a semiconductor crystal at low temperature is able to diffuse or drift macroscopic distances from the point of its creation. This motion can be observed by time-resolved imaging of recombination luminescence or optical absorption. At low densities, the simplest neutral particles -- excitons -- generally exhibit the diffusive motion of classical gases. At high densities, however, the transport behavior can deviate wildly from classical diffusion, as excitonic phase transitions and quantum statistics come into play. In this paper, I will survey a few of the current observations.
    Wolfe, J.P. and Jang, J.I.
    New perspectives on kinetics of excitons in Cu2O 2005 Solid State CommunicationsSpontaneous Coherence in Excitonic Systems
    Vol. 134(1-2), pp. 143-149 
    article DOI  
    Abstract: Ortho-para conversion and Auger recombination of excitons in Cu2O are studied by time- and space-resolved luminescence. The interconversion between orthoexcitons and lower-lying paraexcitons is accurately measured at low excitation levels, where ortho and paraexcitons are in thermal equilibrium. Temperature- and stress-dependences of the interconversion rate D(T, [Delta]) imply that down-conversion occurs by TA phonon emission, which provides the needed rotation of the lattice to induce a spin flip. As the excitation level increases, excitons start to undergo a strong density-dependent Auger recombination. We report the measurements of the Auger constant A(T) over the temperature range 72-212�K. The measured Auger constant is found to depend roughly inversely with the exciton gas temperature over this range and its absolute magnitude is much larger than the present theoretical prediction. The large value of A and a 1/Tgas dependence imply that a thermodynamic BEC of excitons may be impossible to produce in this crystal.
    Wouters, M. and Carusotto, I.
    Excitations in a Nonequilibrium Bose-Einstein Condensate of Exciton Polaritons 2007 Physical Review Letters
    Vol. 99(14), pp. 140402 
    article DOI  
    Abstract: We develop a mean-field theory of the dynamics of a nonequilibrium Bose-Einstein condensate of exciton polaritons in a semiconductor microcavity. The spectrum of elementary excitations around the stationary state is analytically studied by means of a generalized Gross-Pitaevskii equation. A diffusive behavior of the Goldstone mode is found in the spatially homogeneous case and new features are predicted for the Josephson effect in a two-well geometry.
    Wright, A.F. and Nelson, J.S.
    Theory of the copper vacancy in cuprous oxide 2002 Journal of Applied Physics
    Vol. 92, pp. 5849-5951 
    article DOI  
    Abstract: Density-functional theory is used to examine aspects of the copper vacancy (VCu) in cuprous oxide (Cu2O). The normal vacancy configuration, obtained by simple removal of a Cu atom from the lattice, is found to be 0.1 eV higher in energy than a split vacancy configuration wherein a nearby Cu atom is displaced toward a normal vacancy site by half the bulk Cu–Cu separation. Jumps between the normal and split vacancy configurations are predicted to be rate limiting for VCu diffusion with an energy barrier of 0.3 eV. Binding of VCu to substitutional aluminum (AlCu) and indium (InCu) is examined. The neutral (AlCu+2VCu) complex is found to have a binding energy of 3.3 eV whereas the neutral (InCu+2VCu) complex is bound by 1.7 eV. The magnitudes of these binding energies suggest that AlCu and InCu should inhibit VCu diffusion in Cu2O.
    Xiang, J.Y., Wang, X.L., Xia, X.H., Zhang, L., Zhou, Y., Shi, S.J., and Tu, J.P.
    Enhanced high rate properties of ordered porous Cu2O film as anode for lithium ion batteries 2010 Electrochimica Acta
    Vol. In Press, Corrected Proof, pp. - 
    article DOI  
    Abstract: Highly ordered porous Cu2O film is electrodeposited on copper foil through a self-assembled polystyrene sphere template. Compared with the dense Cu2O film and the octahedral Cu2O powder, the ordered porous Cu2O film exhibits an improved electrochemical cycling stability. The capacity of the porous Cu2O film can maintain 336�mAh�g-1 and 213�mAh�g-1 after 50 cycles at the rate of 0.1�C and 5�C, respectively. The reversible capacity holds 63.4% as the discharge-charge rate even increases by 50 times. The enhanced high rate properties of the ordered porous film should be attributed to the sufficient contact surface of Cu2O/electrolyte and the short diffusion length of Li+. Moreover, the direct contact between Cu2O and current collector and the decreasing inactive interfaces of Cu2O/polymer binder are also suggested as being responsible for the enhanced high rate property.
    Xiao, Q., Zhao, X., Huang, L., and Deng, X.
    Primary study of the isothermal phase diagram of the Cu2O-Al2O$_3$-SiO2 ternary system at $1150^rcC$ in air 2007 Rare Metals
    Vol. 26(5), pp. 515-520 
    article DOI  
    Abstract: The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150�C was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150�C for 12 h. Based on the conventional X-ray powder diffraction (XRD) and in situ high-temperature XRD quantitative analysis, in addition to scanning electron microscopy measurement, the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem, the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area, the approximate composition areas of two two-phase regions and one three-phase region, (L2 + Cr), (L2 + M), and (L1 + L2 + Tr), were determined. Moreover, the precise composition areas of both of the three-phase regions (L2 + Cr + M) and (L2 + M + A) were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.
    Xu, H., Wang, W., and Zhu, W.
    A facile strategy to porous materials: Coordination-assisted heterogeneous dissolution route to the spherical Cu2O single crystallites with hierarchical pores 2006 Microporous and Mesoporous Materials
    Vol. 95(1-3), pp. 321-328 
    article DOI  
    Abstract: Porous Cu2O single crystalline spheres with the sizes of 60-100�nm were synthesized by a facile method which involved the reactions based on the chemical properties between NH3, OH-, Cu2+ and Cu2O. The presence of ammonia and the precise control of the molar ratios of the reactants are crucial factors leading to the porous structured Cu2O. The single crystalline framework of the porous Cu2O spheres was produced by the heterogeneous dissolution of the freshly formed single crystalline Cu2O spheres which is similar to the wet chemical etching. As a result, their crystalline character was preserved. Based on the designed experiments and corresponding morphologies of the resultants, the formation mechanism is proposed as coordination-assisted heterogeneous dissolution (CHD). The porous Cu2O possess remarkable photocatalytic activity under visible light irradiation. This strategy to porous materials via CHD is proved to be convenient and efficient, and provide a potential way to achieve porous structures even for other materials.
    Xue, J. and Dieckmann, R.
    The non-stoichiometry and the point defect structure of cuprous oxide (Cu$_2-delta$O) 1990 Journal of Physics and Chemistry of Solids
    Vol. 51, pp. 1263-1275 
    article DOI  
    Abstract: A thermogravimetric study has been performed on the non-stoichiometry of polycrystalline, large-grained cuprous oxide as a function of oxygen activity at temperatures between 800 and 1200°C. The experimental results are analyzed and discussed with regard to the point defect structure of cuprous oxide in combination with literature data on cation diffusion, anion diffusion and electrical conductivity. From the experimental results for the deviation from stoichiometry it is concluded that at least two types of ionic point defects are present as majority defects in Cu2−δO.
    Xue, J. and Dieckmann, R.
    The High-Temperature Phase Diagram of the Cu--O System in Stability Region of Cuprous Oxide (Cu$_2-delta$O) 1992 High Temperatures--High Pressures
    Vol. 24(3), pp. 271-284 
    Yanase, A., Matsui, H., Tanaka, K., and Komiyama, H.
    Optical observation of oxidation and reduction of small supported copper particles 1989 Surface Science Letters
    Vol. 219(3), pp. L601-L606 
    article DOI  
    Abstract: In situ and real-time optical absorption measurements of supported copper particles (4-10 nm) at wavelengths of 300 to 800 nm are carried out under H2, CO, and O2 respectively as ambient gases in the temperature range of 300 to 673 K. We observe a reversible change in the optical spectra caused by oxidation of copper and reduction of copper oxide. The data strongly indicate that the oxidation of small copper particles is composed of a fast process of Cu to CuOx (x [similar, equals] 0.67) and a slow process of CuOx (x [similar, equals] 0.67) to CuO.
    Yang, J.C., Yeadon, M., Kolasa, B., and Gibson, J.M.
    Oxygen surface diffusion in three-dimensional Cu2O growth on Cu$(001)$ thin films 1997 Applied Physics Letters
    Vol. 70(26), pp. 3522-3524 
    article DOI  
    Abstract: By studying the growth of Cu2O islands during the initial oxidation stage of Cu(001) with in situ transmission electron microscopy, it is found that the dominant mechanism for the growth of three-dimensional islands is surface diffusion of oxygen. However, there exists a non-negligible contribution to the metal oxide growth by another mechanism, probably direct impingement of the oxygen atoms on the oxide island. These results demonstrate the importance of surface conditions in oxidation.
    Yang, J.C., Yeadon, M., Olynick, D., and Gibson, J.M.
    Anomalous Desorption of Copper Oxide Observed by In Situ Transmission Electron Microscopy 1997 Microscopy and Microanalysis
    Vol. 3(02), pp. 121-125 
    article DOI  
    Abstract: Here we present our observations of an anomalous desorption of copper oxides from a thin copper film during annealing as observed in an in situ transmission electron microscope. The epitaxial cuprous oxide that formed in air was observed to disappear when the specimen was annealed at 300°C and 10−8 torr. However, removal of the cuprous oxide that formed during oxidation in the microscope required both heating at 300°C and simultaneous exposure to methanol vapor.
    Yang, J.C., Kolasa, B., Gibson, J.M., and Yeadon, M.
    Self-limiting oxidation of copper 1998 Applied Physics Letters
    Vol. 73(19), pp. 2841-2843 
    article DOI  
    Abstract: The classical theory of Cabrera–Mott describes passivation film formation on metals, where they predicted that this film grows as a uniform layer due to a field-enhanced ionic transport mechanism. Here we present experimental evidence, based on in situ transmission electron microscopy of copper oxidation, that the passivation film nucleates and grows as oxide islands, not as a uniform layer. We propose an alternative phenomenological theory to describe passivation film formation, based on island growth followed by coalescence.
    Yang, J.C., Yeadon, M., Kolasa, B., and Gibson, J.M.
    Surface Reconstruction and Oxide Nucleation Due to Oxygen Interaction with Cu$(001)$ Observed by In Situ Ultra-High Vacuum Transmission Electron Microscopy 1998 Microscopy and Microanalysis
    Vol. 4(03), pp. 334-339 
    article DOI  
    Abstract: Reconstruction of the Cu(001) surface due to oxygen gas impingement on a clean copper surface was directly observed by in situ UHV-TEM. Strain contrast between differently oriented surface reconstruction domains, assumed to be [surd radical]2 × 2[surd radical]2 R45, were clearly visible by this method. The reconstruction precedes the nucleation of Cu2O islands. When Cu2O islands were partially reduced and then re-oxidized, a dwell time before formation of Cu2O was noted, demonstrating that a reconstructed Cu-O surface monolayer is necessary before oxide formation.
    Yang, J.C., Bharadwaj, M.D., Zhou, G., and Tropia, L.
    Surface Kinetics of Copper Oxidation Investigated by In Situ Ultra-high Vacuum Transmission Electron Microscopy 2001 Microscopy and Microanalysis
    Vol. 7(06), pp. 486-493 
    article DOI URL 
    Abstract: We review our studies of the initial oxidation stages of Cu(001) thin films as investigated by in situ ultra-high vacuum transmission electron microscopy. We present our observations of surface reconstruction and the nucleation to coalescence of copper oxide during in situ oxidation in O2. We have proposed a semi-quantitative model, where oxygen surface diffusion is the dominant mechanism of the initial oxidation stages of Cu. We have also investigated the effect of water vapor on copper oxidation. We have observed that the presence of water vapor in the oxidizing atmosphere retards the rate of Cu oxidation and Cu2O is reduced when exposed directly to steam.
    Yang, J.C., Evan, D., and Tropia, L.
    From nucleation to coalescence of Cu2O islands during in situ oxidation of Cu$(001)$ 2002 Applied Physics Letters
    Vol. 81(2), pp. 241-243 
    article DOI  
    Abstract: The nucleation, growth, and coalescence of Cu2O islands due to oxidation of Cu(001) films were visualized by in situ ultrahigh-vacuum transmission electron microscopy. We have previously demonstrated that the nucleation and initial growth of copper oxides is dominated by oxygen surface diffusion. These surface models have been extended to quantitatively represent the coalescence behavior of copper oxidation in the framework of the Johnson–Mehl–Avrami–Kolmogorov theory. An excellent agreement exists between the experimental data of nucleation to coalescence with the surface model. The implication could be an alternate paradigm for passivation and oxidation, since classic theories assume uniform film growth.
    Yang, H., Ouyang, J., Tang, A., Xiao, Y., Li, X., Dong, X., and Yu, Y.
    Electrochemical synthesis and photocatalytic property of cuprous oxide nanoparticles 2006 Materials Research Bulletin
    Vol. 41(7), pp. 1310 - 1318 
    article DOI URL 
    Abstract: Cuprous oxide (Cu2O) nanoparticles of 35 nm in crystal size have been successfully synthesized via electrochemical method in alkali NaCl solutions with copper as electrodes and K2Cr2O7 as additive. Photocatalytic degradation of methyl orange (MeO) in aqueous Cu2O solution was investigated under either ultraviolet (UV) light or sunlight. X-ray diffraction (XRD), transmission electron microscopy (SEM), Fourier transformation infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and X-ray photoelectron spectroscopy (XPS) were introduced to characterize the samples. The results indicate that electric current shows no obvious effect on the growth of Cu2O nanocrystals and that 97% of MeO can be decolorized under UV irradiation for 2 h or under sunlight for 3 h when amount of Cu2O is 2 g/L. Recycling use of the catalyst revealed that Cu2O still has a high photocatalytic efficiency when repeatedly used for four times. Cu2O nanoparticles still kept its cubic crystal phase, but fractionally oxidized to be CuO after the photocatalysis. Compared with the original Cu2O nanoparticles, there has 1 eV shift of Cu 2p electron and 1.6 eV shift of Cu Auger signals for the Cu2O powders after four times photocatalysis. Some new peaks can also be observed at 401.1, 237.4 and 170.2 eV in the Cu2O powders after photocatalysis.
    Yang, W.-Y. and Rhee, S.-W.
    Effect of electrode material on the resistance switching of Cu2O film 2007 Applied Physics Letters
    Vol. 91(23), pp. 232907 
    article DOI  
    Abstract: The effect of the bottom electrode material on the resistance switching characteristics was evaluated on the structure of Pt/Cu2O/bottom electrode). It was confirmed that Ohmic or low Schottky contact is needed to induce the effective electric field for resistance switching across the Cu2O film. Pt, TiN, TaN, and strontium-ruthenium oxide belong to this group. For high Schottky contact, the resistance switching characteristics could not be observed due to a large voltage drop at the rectifying interface with insufficient electric field in the Cu2O film. Also, it was confirmed that interlayer formation from the reaction at the electrode-oxide interface increased the barrier height and brought about the switching failure in the case of Ru. The resistance switching properties depend on the barrier height and the reactivity between metal and Cu2O film.
    Yang, W.-Y., Kim, W.-G., and Rhee, S.-W.
    Radio frequency sputter deposition of single phase cuprous oxide using Cu2O as a target material and its resistive switching properties 2008 Thin Solid Films
    Vol. 517(2), pp. 967-971 
    article DOI  
    Abstract: Single phase cuprous oxide (Cu2O) thin films were deposited on TiN substrate with radio frequency sputtering. Cu2O was used as a target material without oxygen to avoid the formation of Cu2O and CuO mixture which was formed in copper oxidation or when using Cu target along with Ar and O2. Single phase cuprous oxide was confirmed with X-ray diffraction and X-ray photoelectron spectroscopy measurements. Typical growth rate of Cu2O thin film was 14�nm/min under the optimized process condition. Cu2O thin films were thermally stable up to 250��C, while the phase separation occurred above 350��C. Fundamental properties of Cu2O thin films such as resistivity, mobility, and dielectric constant were obtained. Current-voltage characteristics of Pt/Cu2O/TiN-based structure showed two stable resistance states through the double voltage sweep between -�2�V and +�2�V. The electrical properties of this structure were described well with space charge-limited conduction mechanism and the full energy-band structure of Cu2O film was obtained.
    Yao, K.X., Yin, X.M., Wang, T.H., and Zeng, H.C.
    Synthesis, Self-Assembly, Disassembly, and Reassembly of Two Types of Cu2O Nanocrystals Unifaceted with $001$ or $110$ Planes 2010 Journal of the American Chemical Society
    Vol. 132, pp. 6131-6144 
    article DOI  
    Abstract: In this work, we describe a solution-based synthesis of monodisperse Cu2O nanocrystals with controllable sizes in the nanoscale regime. Two types of nanocrystals, cubes and rhombic dodecahedra unifaceted with either 001 or 110 crystal planes, have been prepared at a 100% morphological yield. In particular, synthetic parameters and formation processes of the Cu2O nanocrystals have been investigated in detail, and a range of well-oriented supercrystals/superlattices built from the two types of nanobuilding blocks have been attained for the first time. It has been revealed that n-hexadecylamine used in the present work plays multiple roles: it serves as a chelating ligand to form [Cu(NH2C16H33)4]2+ complex precursor, as a phase-transferring agent to transfer divalent Cu2+ ions into the organic phase, as a reducing agent to generate monovalent Cu+ (i.e., Cu2O), as a passivating adsorbate to control crystal morphology, and as a surface capping agent to generate self-assemblies of nanocrystals via van der Waals interaction. Apart from synthesis and self-assembly, disassembly and reassembly of Cu2O nanocrystals have also been investigated. The disassembly processes are accompanied with aggregative growths of nanocrystals, which can be attributed to a combined process of “oriented attachment” and Ostwald ripening, leading to permanent engagement and enlargement of nanocrystals. Finally, our self-assembled nanocrystals of Cu2O show a lower detection limit, lower operating temperature, and higher sensitivity in ethanol vapor detection, compared with other Cu2O-based alcohol sensors reported in the recent literature. A greater depletion layer of carrier and a relatively small contact potential may account for the observed sensing enhancement in the sensors made from the organized Cu2O nanocrystals.
    Yin, M., Wu, C.-K., Lou, Y., Burda, C., Koberstein, J.T., Zhu, Y., and O'Brien, S.
    Copper Oxide Nanocrystals 2005 Journal of the American Chemical Society
    Vol. 127(26), pp. 9506-9511 
    article DOI  
    Abstract: It is well-known that inorganic nanocrystals are a benchmark model for nanotechnology, given that the tunability of optical properties and the stabilization of specific phases are uniquely possible at the nanoscale. Copper (I) oxide (Cu2O) is a metal oxide semiconductor with promising applications in solar energy conversion and catalysis. To understand the Cu/Cu2O/CuO system at the nanoscale, we have developed a method for preparing highly uniform monodisperse nanocrystals of Cu2O. The procedure also serves to demonstrate our development of a generalized method for the synthesis of transition metal oxide nanocrystals. Cu nanocrystals are initially formed and subsequently oxidized to form highly crystalline Cu2O. The volume change during phase transformation can induce crystal twinning. Absorption in the visible region of the spectrum gave evidence for the presence of a thin, epitaxial layer of CuO, which is blue-shifted, and appears to increase in energy as a function of decreasing particle size. XPS confirmed the thin layer of CuO, calculated to have a thickness of 5 A. We note that the copper (I) oxide phase is surprisingly well-stabilized at this length scale.
    Yoon, K.H., Choi, W.J., and Kang, D.H.
    Photoelectrochemical properties of copper oxide thin films coated on an $n$-Si substrate 2000 Thin Solid Films
    Vol. 372(1-2), pp. 250-256 
    article DOI  
    Abstract: The photoelectrochemical properties of the copper oxide thin film coated on the n-type silicon electrode were investigated as a function of film deposition temperature. The variation in the deposition temperature affected the film morphology and the ratio of copper to oxygen. In case of the films deposited below 200�C, the main phase was found to be CuO while the amount of the Cu2O phase increased with further increases in deposition temperature. The n-silicon photoelectrode showed enhanced photocurrent-potential (I-V) properties by forming a copper oxide/n-silicon heterojunction. In particular, the electrode, which mainly consisted of a CuO phase, showed better photoelectrochemical conversion efficiencies compared to the Cu2O phase. This result was explained in terms of the electrical conductance and transmittance of the copper oxide film.
    Yoshimura, M., Revcolevschi, A., and Castaing, J.
    Thermogravimetric study of the non-stoichiometry of cuprite Cu2O 1976 Journal of Materials Science
    Vol. 11(2), pp. 384-386 
    article DOI  
    Young Jr., F.W., Cathcart, J.V., and Gwathmey, A.T.
    The rates of oxidation of several faces of a single crystal of copper as determined with elliptically polarized light 1956 Acta Metallurgica
    Vol. 4(2), pp. 145-152 
    article DOI  
    Abstract: The rates of oxidation of the (100), (111), (110) and (311) faces of a copper single crystal were determined at the temperatures 70�, 106�, 130�, 159�, and 178�C by measuring the increase in thickness of the oxide film as a function of time. A polarizing spectrometer was used to measure film-thickness. Particular emphasis was placed on preparing a smooth, clean, strain-free surface of known orientation. The relative order of the rates of oxidation of these faces was found to be (100), (111), (110), (311) in decreasing order. The results showed the great difference in the rate of oxidation with crystal face at these temperatures, the ratio of the thickness of the oxide on the (100) face to that on the (311) face being 12.5 for oxidation at 178�C. An analysis of the results, according to the present theories of the oxidation of metals, was presented.
    Yu, P.Y., Shen, Y.R., Petroff, Y., and Falicov, L.M.
    Resonance Raman Scattering at the Forbidden Yellow Exciton in Cu2O 1973 Physical Review Letters
    Vol. 30(7), pp. 283-286 
    article DOI  
    Abstract: We report strong resonance enhancement in the 220-cm-1 Raman line of Cu2O at the Γ12--phonon-assisted absorption threshold of the forbidden 1s yellow exciton. A consistent theoretical interpretation is presented. It shows that the line is due to scattering of two Γ12- phonons and the resonance enhancement is strongly affected by the exciton lifetime. The latter effect has never been considered or observed before in resonance Raman scattering.
    Yu, P.Y. and Shen, Y.R.
    Multiple Resonance Effects on Raman Scattering at the Yellow-Exciton Series of Cu2O 1974 Physical Review Letters
    Vol. 32(7), pp. 373-376 
    article DOI  
    Abstract: We have observed sharp resonance enhancements in some two-phonon Raman modes of Cu2O around the n=2 to 6 peaks of the yellow-exciton series. We explain the results quantitatively by a theory which allows for multiple resonances in the scattering process.
    Yu, P.Y. and Shen, Y.R.
    Study of Dispersive Raman Modes in Cu2O by Resonant Raman Scattering 1974 Physical Review Letters
    Vol. 32(17), pp. 939-942 
    article DOI  
    Abstract: We have observed shifts in energy of a number of Raman modes of Cu2O as a function of incident photon energy. We explain such energy shifts as due to dispersion in the phonons involved and obtain quantitative agreement between theory and experiment. From our data we have also determined the effective mass of the 1s yellow exciton in Cu2O to be (3.0±0.2)m0.
    Yu, Y., Ma, L.-L., Huang, W.-Y., Li, J.-L., Wong, P.-K., and Yu, J.C.
    Coating MWNTs with Cu2O of different morphology by a polyol process 2005 Journal of Solid State Chemistry
    Vol. 178(5), pp. 1488-1494 
    article DOI  
    Abstract: Homogeneous cuprous oxide (Cu2O) nanoparticles with size of 8-10 nm are deposited on multiwall carbon nanotubes (MWNTs) by a polyol process using Cu(CH3COO)2·H2O as a precursor and diethylene glycol as both solvent and reducing agent. The composition of the resulting Cu2O/MWNTs composites is confirmed by XRD pattern, XPS spectrum and HRTEM images. With the change of the reaction conditions, it is found that Cu2O nanoparticles on the surface of MWNTs can be leafage-like or big spherical particle coated on the surface of MWNTs. HRTEM images indicate that all the leafage-like and big spherical particles are assembled by small Cu2O particles with size of about 2-5 nm. With the assistance of FTIR spectrum, a tentative mechanism is proposed for the formation of Cu2O nanoparticles with different morphologies on the surface of MWNTs.
    Yund, R.A. and Kullerud, G.
    Stable mineral assemblages of anhydrous copper and iron oxides 1964 The American Mineralogist
    Vol. 49, pp. 689-696 
    article URL 
    Zerbino, J.O. and Gassa, L.M.
    Electrochemical impedance spectroscopy study of cuprous oxide films formed on copper: effect of pH and sulfate and carbonate ions 2003 Journal of Solid State Electrochemistry
    Vol. 7(3), pp. 177-182 
    article DOI  
    Abstract: Abstract.&nbsp;&nbsp; The semiconducting properties of anodic passive films formed potentiostatically on polycrystalline copper in aqueous borax solutions were studied using electrochemical impedance spectroscopy, photocurrent spectroscopy and ellipsometric measurements. The semiconducting nature of the cuprous passive layer was analysed as a function of pH (9.2&gt;pH&gt;7.4), electrode potential and with the addition of 3.5&nbsp;mM Na2CO3 and 8&nbsp;mM Na2SO4. The different growth conditions change the compactness and the defect or excess of cations accumulated in the compact inner cuprous layer, leading to different semiconducting properties.
    Zhang, D.K., Liu, Y.C., Liu, Y.L., and Yang, H.
    The electrical properties and the interfaces of Cu2O/ZnO/ITO p--i--n heterojunction 2004 Physica B
    Vol. 351(1-2), pp. 178-183 
    article DOI  
    Abstract: A Cu2O/ZnO/ITO p-i-n heterojunction was fabricated by electrochemical deposition method. The electrical properties of the p-Cu2O/i-ZnO/n-ITO heterojunction were studied using the current-voltage measurements. A distinct junction characteristic was observed. Here, the forward and reverse turn-on voltages were about 0.53 and -0.60�V, respectively. An energy-band diagram was proposed to analyze the electrical properties. In terms of the results of the current-voltage measurements, it was deduced that the turn-on voltage was smaller than the barrier potential, which was ascribed to the existence of the interface defect states. The mechanism of charge transportation was discussed and a tunnel recombination process was proposed to explain its electrical properties.
    Zhang, J., Liu, J., Peng, Q., Wang, X., and Li, Y.
    Nearly Monodisperse Cu2O and CuO Nanospheres: Preparation and Applications for Sensitive Gas Sensors 2006 Chemistry of Materials
    Vol. 18(4), pp. 867-871 
    article DOI  
    Zhang, K., Rossi, C., Tenailleau, C., Alphonse, P., and Chane-Ching, J.-Y.
    Synthesis of large-area and aligned copper oxide nanowires from copper thin film on silicon substrate 2007 Nanotechnology
    Vol. 18(27), pp. 275607 
    article DOI  
    Abstract: Large-area and aligned copper oxide nanowires have been synthesized by thermal annealing of copper thin films deposited onto silicon substrate. The effects of the film deposition method, annealing temperature, film thickness, annealing gas, and patterning by photolithography are systematically investigated. Long and aligned nanowires can only be formed within a narrow temperature range from 400 to 500 °C. Electroplated copper film is favourable for the nanowire growth, compared to that deposited by thermal evaporation. Annealing copper thin film in static air produces large-area, uniform, but not well vertically aligned nanowires along the thin film surface. Annealing copper thin film under a N 2 /O 2 gas flow generates vertically aligned, but not very uniform nanowires on large areas. Patterning copper thin film by photolithography helps to synthesize large-area, uniform, and vertically aligned nanowires along the film surface. The copper thin film is converted into bicrystal CuO nanowires, Cu 2 O film, and also perhaps some CuO film after the thermal treatment in static air. Only CuO in the form of bicrystal nanowires and thin film is observed after the copper thin film is annealed under a N 2 /O 2 gas flow.
    Zhao, W., Fu, W., Yang, H., Tian, C., Ge, R., Wang, C., Liu, Z., Zhang, Y., Li, M., and Li, Y.
    Shape-controlled synthesis of Cu2O microcrystals by electrochemical method 2010 Applied Surface Science
    Vol. 256(7), pp. 2269-2275 
    article DOI  
    Abstract: Cuprous oxide (Cu2O) microcrystals have been successfully synthesized via a facile electrochemical method in alkaline NaCl solution with copper plate and graphite slice as electrodes and Na2Cr2O7 as additive. The as-synthesized products have been systematically studied by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), selected area electron diffraction (SAED) and ultraviolet-visible spectrum (UV-vis). The results indicate that the pH value, temperature and potential play important roles in the morphology control besides the crystal habits of Cu2O. The possible mechanism has been explored in the article.
    Zhilich, A.G., Halpern, J., and Zakharchenya, B.P.
    Magnetoabsorption Oscillations and the Zeeman Effect of Excitons for Forbidden Interband Transitions in Cu2O Crystals 1969 Physical Review
    Vol. 188(3), pp. 1294-1302 
    article DOI  
    Abstract: Magnetoabsorption oscillations were studied in cubic Cu2O at 1.5°K for Γ7+→Γ6+ forbidden interband transitions in strong dc magnetic fields. The theoretical analysis indicates that in the case of forbidden transitions, oscillations in the magnetoabsorption enable one to evaluate the electron and hole effective masses separately; these were found to be me=0.61m0 and mh=0.84m0. The effective magnetic moment of the hole was determined to be βh=-1.3×10-5 G-1cm-1. The dielectric constant for Cu2O calculated from these data is ε0=7.1. The Zeeman effect of the yellow-series exciton lines was also studied both experimentally and theoretically.
    Zhou, Y.C. and Switzer, J.A.
    Galvanostatic electrodeposition and microstructure of copper (I) oxide film 1998 Materials Research Innovations
    Vol. 2(1), pp. 22-27 
    article DOI  
    Abstract: Abstract&nbsp;&nbsp; Polycrystalline copper (I) oxide films were deposited on stainless steel substrate by galvanostatic electrodeposition method and were characterized by X-ray diffraction and scanning electron microscopy. The effect of bath temperature, bath pH and current density on the compositon, grain size, surface texture and surface morphology of the electrodeposited films were investigated. The films deposited at low bath pH (≤7) consisted of copper (I) oxide and metallic copper; while the films deposited at bath pH between 8 and 12 and bath temperature of 60°C were pure copper (I) oxide. The preferred orientation of the copper (I) oxide films depended on the relative growth rate of 111 and 200 faces and could be controlled by adjusting the bath pH and/or the cathodic current density. (100)-oriented copper (I) oxide films could be deposited at pH=9 and current densities in the range of 0.25–1&nbsp;mA/cm2, while (111)-oriented films could be prepared at pH=12 or at pH=9 using the current densities between 1.5–2.5 mA/cm2. Computer simulated crystallite shapes showed that the crystal shape changed from octahedral for (100)-oriented film to trucated pyramids and cubs for (111)-oriented film. And they were approved by scanning electron microscopy.
    Zhou, Y. and Switzer, J.A.
    Electrochemical Deposition and Microstructure of Copper (I) Oxide Films 1998 Scripta Materialia
    Vol. 38(11), pp. 1731-1738 
    article DOI  
    Zhou, G. and Yang, J.C.
    Formation of Quasi-One-Dimensional Cu2O Structures by in situ Oxidation of Cu$(100)$ 2002 Physical Review Letters
    Vol. 89(10), pp. 106101 
    article DOI  
    Abstract: Epitaxial Cu2O islands on a Cu(100) surface formed through oxidizing Cu(100) films at 600 °C in an ultrahigh vacuum transmission electron microscope were observed to undergo a shape transition from initially square shaped islands to elongated islands at a critical size of ~110 nm. Our experimental data on the elongation of Cu2O islands agree with the energetic calculations based on the balance between surface and interface energies and the elastic stress relaxation in the three-dimensional islands. We developed a kinetic model based on oxygen surface diffusion that fits well with the observed volume evolution of the Cu2O islands.
    Zhou, G.
    Temperature effect on the Cu2O oxide morphology created by oxidation of Cu$(001)$ as investigated by in situ UHV TEM 2003 Applied Surface Science
    Vol. 210, pp. 165-170 
    article DOI  
    Abstract: The temperature effect on the Cu2O oxide morphology was investigated by oxidizing Cu(1 0 0) thin films at the temperature ranging from 150 to 1000 °C and constant oxygen partial pressure of 5×10−4 Torr. The evolution of the oxide island size and shape was followed inside an in situ ultrahigh vacuum transmission electron microscope (UHV TEM). Of particular interest, we find that the oxide morphology can be triangular, hut, rod or pyramid shaped depending only on the oxidation temperature.
    Zhou, G. and Yang, J.C.
    In situ UHV-TEM investigation of the kinetics of initial stages of oxidation on the roughened Cu$(110)$ surface 2004 Surface Science
    Vol. 559, pp. 100-110 
    article DOI  
    Abstract: The initial stages of oxidation on roughened Cu(1 1 0) surface were explored by an in situ ultra-high vacuum transmission electron microscope (UHV-TEM). The dynamic observation of the nucleation and growth of Cu oxide islands shows a highly enhanced nucleation rate on the roughened Cu(1 1 0) surface. The kinetic data obtained from the initial stages of the oxidation indicate that oxygen surface diffusion plays a dominant role in the nucleation of the oxide islands; however, the growth of the three-dimensional oxide islands is caused by both oxygen surface diffusion and direct impingement.
    Zhou, G. and Yang, J.C.
    Temperature effects on the growth of oxide islands on Cu$(110)$ 2004 Applied Surface Science
    Vol. 222, pp. 357-364 
    article DOI  
    Abstract: We examined the Cu2O island formation on Cu(1 1 0) as a function of oxidation temperature in the range of 450–650 °C and oxygen pressure of 0.1 Torr. Epitaxial three-dimensional trapezoid island formation was observed for oxidation at the all temperatures and it was found that increasing oxidation temperature increased the thickening rate of the oxide islands. The oxidation at 0.1 Torr was noted to have a smaller nucleation activation energy for the oxide formation as compared to lower pressures.
    Zhu, Y., Qian, Y., Zhang, M., Chen, Z., Xu, D., Yang, L., and Zhou, G.
    Preparation and characterization of nanocrystalline powders of cuprous oxide by using [gamma]-radiation 1994 Materials Research Bulletin
    Vol. 29(4), pp. 377-383 
    article DOI  
    Abstract: The [gamma]-radiation method has been firstly used to prepare nanocrystalline powders of cuprous oxide from cupric sulfate aqueous solution in the presence of buffer pair. X-ray powder diffraction reveals that the product is single phase of cuprous oxide. Electron microscopy shows that the average particle size of cuprous oxide prepared is about 14 nm. Influences of experimental conditions on particle size of cuprous oxide and the mechanism of the formation of cuprous oxide are discussed.
    Zhu, Y., Mimura, K., and Isshiki, M.
    Oxidation Mechanism of Copper at $623$-$1073K$ 2002 Materials Transactions
    Vol. 43(9), pp. 2173-2176 
    article URL 
    Abstract: In reviewing the results reported for copper oxidation at intermediate temperatures from 573 to 1173 K, the oxidation mechanism at the lower part of this temperature range and the reason for the change in activation energy with decreasing the temperature remain unclear. To make it clear, copper oxidation is studied at 623-1073 K under 0.1 MPa O2 using a commercial 99.9999% pure copper. The oxidation kinetics is essentially parabolic, and the activation energy decreases from 111 kJ/mol at 873-1073 K to 40 kJ/mol at 623-773 K. The growth of Cu2O is predominant and it obeys the parabolic law at 623-773 K, as well as the case at 873-1073 K. In addition to grain boundary diffusion of copper along the fine and thin columnar Cu2O grains, the non-protective CuO whisker layer, which cannot keep the oxygen potential constant at the Cu2O/CuO interface, should be responsible for the decrease in the activation energy at 623-773 K.
    Zhu, Y., Mimura, K., and Isshiki, M.
    Purity Effect on Oxidation Kinetics of Copper at $800$-$1050 ^rc C$ 2004 Journal of The Electrochemical Society
    Vol. 151, pp. B27-B32 
    article DOI  
    Abstract: To clarify the purity effect on copper oxidation kinetics, oxidation was carried out at 800-1050°C using 99.99% (4 N), 99.9999% (6 N) and floating zone refined (FZR, >99.9999%) copper specimens. In the Arrhenius plots of the parabolic oxidation rate constants for the double-layer (dl) formation (Cu2O + CuO) at 800-1050°C in 0.1 MPa O2 atmosphere, the points for FZR copper essentially followed a straight line. For 6 N and 4 N coppers, the oxidation kinetics at high temperatures (above 950°C) was almost the same as that for FZR copper, but the points at lower temperatures followed two lines with smaller slopes. This result suggests that the oxidation of FZR copper was governed by the lattice diffusion at 800-1050°C. Trace impurities had almost no influence on the oxidation kinetics of 6 N and 4 N coppers at temperatures above 950°C where the lattice diffusion predominated. However, at lower temperatures where the grain boundary diffusion also contributes to oxidation, trace impurities decreased the activation energy by impeding the growth of Cu2O grains to facilitate the grain boundary diffusion. The activation energy governed by the lattice diffusion was 173 kJ/mol for the dl formation, while it was 98 kJ/mol for the single-layer formation (Cu2O). This supports a (pO2)1/4 dependence of the parabolic rate constant associated with the diffusion of copper atoms via neutral copper vacancies in the Cu2O layer.
    Zhu, Y., Mimura, K., and Isshiki, M.
    The Effect of Impurities on the Formation of the Inner Porous Layer in the Cu2O Scale During Copper Oxidation 2004 Oxidation of Metals
    Vol. 61(3), pp. 293-301 
    article DOI  
    Abstract: The effect of impurities on the formation of the inner porous layer in the Cu2O scale during copper oxidation was examined using 99.99 (4N), 99.9999% (6N) and floating-zone-refined (FZR, >99.9999) copper specimens at 800° C. Oxidation for 240 min shows that an inner porous layer was formed in the Cu2O scale near the Cu2O/Cu interface for 4N copper, but not for 6N and FZR copper. The results support that the inner porous layer in the oxide scale is related to impurities from the metal base.
    Zhu, Y., Mimura, K., and Isshiki, M.
    Oxidation Mechanism of Cu2O to CuO at $600$-$1050^rcC$ 2004 Oxidation of Metals
    Vol. 62(3), pp. 207-222 
    article DOI  
    Abstract: To clarify the oxidation mechanism of Cu2O to CuO, Cu2O oxidation was studied at 600–1050 °C under 1atm O2. The Cu2O specimens were prepared through completely oxidizing 99.99999 and 99.5 pure copper at 1000°C in an Ar + 1 O2 atmosphere. The oxidation kinetics of Cu2O specimens prepared from both purity levels followed the logarithmic law, not the parabolic law or the cubic law as reported in the literature. The activation energy for Cu2O oxidation is relatively high in the lower-temperature range, but becomes very small or even negative at higher temperatures. The logarithmic oxidation rate law can be explained by Davies et al.’s model related to grain-boundary diffusion in the oxide layers. The very small or negative activation energies in the higher-temperature range can be attributed to the very small thermodynamic driving force and the fast lateral growth of CuO grains related to a sintering effect. The influence of small amount of impurities is also discussed.
    Zhu, Y., Mimura, K., and Isshiki, M.
    A study of the initial oxidation of copper in $0.1MPa$ oxygen and the effect of purity by metallographic methods 2004 Corrosion Science
    Vol. 46(10), pp. 2445-2454 
    article DOI  
    Abstract: To clarify the initial oxidation mechanism of copper, the oxidation was carried out at 400 �C in 0.1 MPa oxygen using 99.9999% (6 N) and 99.5% (2 N) pure specimens. Oxidation of 6 N copper after 60 s showed that the number density of the oxide nuclei varied with the face of copper crystals, while the nucleation occurred preferentially at the grain boundaries. A metallographic examination indicated that the products of initial oxidation consist of both CuO and Cu2O. CuO is firstly formed as a thin uniform film on the copper surface, and then Cu2O nucleates and grows beneath the CuO film. This result is different from the conclusion reached in the literature that CuO does not appear until the laterally growing Cu2O nuclei have covered the whole surface using other methods. In contrast to 6 N copper, nucleation of Cu2O was much delayed for 2 N copper, though a thin CuO film was similarly formed on 2 N copper surface. Impurities in 2 N copper should be responsible for slow nucleation of Cu2O and slow growth of nuclei.
    Zielinger, J.P., Zouaghi, M., and Coret, A.
    Étude de l'effet photo-Hall dans la cuprite à $79^rcK$ 1966 Journal de Physique
    Vol. 27(3-4), pp. 166-172 
    article DOI  
    Abstract: The photo-Hall effect in cuprous oxide at 79 °K was investigated in order to determine the nature of the photoconductivity in the visible (0.4 to 0.63 μ) and infrared (0.8 to 2.5 μ) parts of the spectrum. In the visible part the photoconductivity is bipolar, while in the I. R. part it is essentially p type. Some parameters of the photocarriers (mobility, mean free path, diffusion constant, etc...) have been determined.
    Zielinger, J.P., Zouaghi, M., Fortin, E., and Weichman, F.L.
    Photomagnetorectification effect in Cu2O at $77^rcK$ 1967 Physics Letters A
    Vol. 24(7), pp. 397-399 
    article DOI  
    Abstract: A new rectification effect is found in Cu2O illuminated with strongly absorbed light in crossed electric and magnetic fields. The rectification ratio increases with B and V and reaches a value of 10 for B = 1.9 Wb/m2, V = 300 volt and .
    Zielinger, J.P., Weichman, F.L., Zouaghi, M., and Fortin, E.
    Préparation d'échantillons de Cu2O de forte résistivité et étude de leurs propriétés photogalvanomagnétiques aux basses températures. Description des méthodes et du montage utilisés 1968 Revue de Physique Appliquée
    Vol. 3(2), pp. 143-151 
    article DOI  
    Abstract: We describe a method for the preparation of polycrystalline cuprous oxide of very low conductivity. Such samples are obtained by annealing in vacuum at high temperature. The experimental device is built in such a way as to allow both the preparation of the samples and the subsequent measurements at low temperatures of the conductivity, Hall effect, photoconductivity, photo-Hall effect and photomagnetoelectric (PME) effect without removing the samples from the vacuum. The electrical circuit is adapted to make studies on high resistivity samples (up to 1012 ohms) . A detailed description of the set-up is given.
    Zielinger, J.P., Tapiero, M., Roubaud, C., and Zouaghi, M.
    Etude de la variation thermique de la conductivite electrique interne de monocristaux de Cu2O 1970 Solid State Communications
    Vol. 8, pp. 1299-1302 
    article DOI  
    Abstract: The bulk conductivity of Cu2O single crystals was measured using a guard ring technique, from - 80°C to + 400°C in vacuum. The experimental results are interpreted in terms of two acceptor levels and a donor level.
    Zielinger, J.P., Tapiero, M., and Noguet, C.
    Conductibilité Électrique De Cu2O. II. Résultats Expérimentaux 1972 Annales de Physique
    Vol. 7, pp. 95-114 
    article URL 
    Zielinger, J.P., Tapiero, M., and Noguet, C.
    Improved methods of measuring DC surface and bulk resistivities using guarded electrodes 1973 Journal of Physics E
    Vol. 6(6), pp. 579 
    article DOI  
    Abstract: Two methods, based on the guarded electrode technique, are proposed for the determination of volume and surface conductivities. They are suitable for measuring resistances ranging from 10 2 to 10 12 Omega . The so-called bridge method needs a manual balance and gives simultaneously both conductivities. The semi-automatic bridge method does not need a manual balance, but allows the determination of only one of the two conductivities. The accuracy is better than 2% as long as the ratio of volume to surface resistances is less than about 10 3 .
    Zielinger, J.P., Noguet, C., and Tapiero, M.
    Photomemory Effect in Cu2O Single Crystals. Kinetics of the Excitation and De-Excitation Processes 1977 Physica Status Solidi (a)
    Vol. 42, pp. 91-100 
    article DOI  
    Abstract: A theoretical analysis of the kinetics of the excitation and de-excitation processes is presented. It is based on the energy level diagram which has been proposed in a previous paper, for the interpretation of the phenomenology of the photomemory effect. A simple, although general, mathematical treatment of the problem, is given. A good agreement is found between the theoretical predictions and the experimental results. The excitation process closely satisfies the reciprocity law. The depths and the capture cross sections of traps A and B are determined by two independent methods. The first one is based on a fit between the theoretical and experimental thermal variations of the density of trapped electrons at constant heating rate; the second one uses the correlation between the temperature of the conductivity maximum and the heating rate. The nature of the trapping centres is discussed.
    Ziomek, J.S.
    Multiphonon selection rules for cuprous oxide type crystalline systems 1982 Journal of Physics and Chemistry of Solids
    Vol. 43(11), pp. 1037-1044 
    article DOI  
    Abstract: Experimental data on the IR and Raman spectra along with the slow coherent neutron scattering data for Cu2O were examined for assignments of frequencies to phonon modes not only at the center but those at the boundary of the Brillouin zone. The inconsistency in assignments for the zone center modes and the lack of not only assignments but identifications of the zone boundary phonon required the use of second order Raman and IR spectra as the useful probes. The basis for the interpretation of these spectral data is given in terms of reduction coefficients for ordinary products and symmetrized squares and cubes of representations in the "cuprite" structure Oh4-Pn3m. They are presented for the R, X, M and [Gamma] points of the Brillouin zone. They will serve for obtaining selection rules, invariants, and covariants for this structure. Additional tables are given that enable one to identify what pair of phonons correspond to electric dipole, magnetic dipole, electric quadrupole, or Raman transitions, respectively.
    Zirin, M.H. and Trivich, D.
    Thermoelectric Effect in Single-Crystal Cuprous Oxide at High Temperatures 1963 Journal of Chemical Physics
    Vol. 39(4), pp. 870-875 
    article DOI  
    Abstract: The thermoelectric effect in single‐crystal cuprous oxide, measured at temperatures of 500° to 1130°C and oxygen pressures P of 160 to 2×10—6 Torr, was found always to be positive, indicating that the material is a p‐type semiconductor in these ranges of conditions.
    Plots of the thermoelectric power Q vs 1/T at different constant oxygen pressures yield parallel straight lines with a slope of 0.75 V. Plots of Q vs logP are mostly straight lines with slopes approximating (—2.3k) / (8q), in which k is Boltzmann's constant and q is the electronic charge.
    These results can be explained fairly satisfactorily in terms of a modified Wagner model for the defect structure of Cu2O and existing theories of the thermoelectric effect in semiconductors. It is assumed that the concentration of acceptors is a function of both the oxygen pressure and the temperature and that a gradient of acceptors exists along the temperature gradient. Thus, the model shows that the factor 8, originally obtained from conductivity measurements, should also be contained in the slope of Q vs logP. The slope of 0.75 V for the plot of Q vs 1/T can be related to the energy of creating an acceptor, i.e., a copper atom vacancy, plus the energy of ionizing this acceptor.
    Zou, B., Zheng, X., Tang, G., Zhang, G., and Chen, W.
    Excitonic properties of Cu2O microcrystals 1993 Physics Letters A
    Vol. 182(1), pp. 130-134 
    article DOI  
    Abstract: In this paper we for the first time report on the excitonic properties of Cu2O microcrystals in the exciton confinement regime. We have found that the optical response of different exciton series can occur at room temperature, and the discrete Rydberg level of the optically allowed exciton transitions is in agreement with Hanamura's prediction.
    Zouaghi, M., Fortin, E., and Zielinger, J.P.
    Inversion of the PEM effect in thin Cu2O films 1967 Physics Letters A
    Vol. 25(1), pp. 51-52 
    article DOI  
    Abstract: Reversal of the PEM effect, in the exciton peaks and the continuous background, has been shown to occur in Cu2O films in the 3400 to 5000 � range. The phenomenon is interpreted in terms of lifetime inhomogeneities across the sample thickness, and could become a means of measuring exciton diffusion lengths.
    Zouaghi, M., Coret, A., and Eymann, J.O.
    Infrared Induced Photoconductivity In Cuprous Oxide 1969 Solid State Communications
    Vol. 7, pp. 311-313 
    article DOI  
    Abstract: Near i.r. photoconductivity in Cu2O at 110°K is enhanced by illumination of samples at room temperature. This effect is interpreted by a charge transfer of carriers between stoichiometric defects.
    Zouaghi, M., Tapiero, M., Zielinger, J.P., and Burgraf, R.
    Hall Mobility and Hole Density in Photoactivated Cu2O Single Crystals 1970 Solid State Communications
    Vol. 8, pp. 1823-1825 
    article DOI  
    Abstract: The photomemory effect in Cu2O is found to be due to a considerable increase of the hole density and to a slight increase of the Hall mobility μH. The variation of μH vs. T is interpreted by two scaterring processes: optical phonons and ionized defects.
    Zouaghi, M.
    Near Infrared Optical and Photoelectric Properties of Cu2O. II. Near Infrared Photoconductivity in Cu2O: Influence of Annealing 1972 Physica Status Solidi (a)
    Vol. 11, pp. 219-227 
    article DOI  
    Zouaghi, M., Prevot, B., Carabatos, C., and Sieskind, M.
    Near Infrared Optical and Photoelectric Properties of Cu2O. III. Interpretation of Experimental Results 1972 Physica Status Solidi (a)
    Vol. 11, pp. 449-460 
    article DOI  
    Zucker, R.S.
    Growth of Single Crystal Cuprous Oxide from the Melt and Luminescence of Cuprous Oxide 1965 Journal of the Electrochemical Society
    Vol. 112, pp. 417-420 
    article DOI  
    Abstract: A number of crucible materials were evaluated for melting Cu2O. Only MgO appears to be sufficiently nonreactive for use in crystal growing. A melt of cuprous oxide contained in a magnesia crucible when cooled at a rate of 2.5°C per hour produced large single crystals. Attempts to accelerate growth by cooling at a rate of 13.5°C per hour produced only small polycrystals. A (100) seed cut from the single crystal along natural cleavage lines was used to pull a crystal from the melt by the Czochralski method. A tendency to grow off-axis resulted in beautiful subsurface facets of transparent ruby-red material. Two new forms of luminescence were observed during rapid cooling of solid cuprous oxide. From 1175° to 1145°C continuous light emission was observed in the yellow-green region. From 1125° to 975°C flashing points of light were observed in the same spectral region.
    Zuo, J.M., Kim, M., O'Keeffe, M., and Spence, J.C.H.
    Direct observation of $d$-orbital holes and Cu--Cu bonding in Cu2O 1999 Nature
    Vol. 401(6748), pp. 49-52 
    article DOI  
    Abstract: A striking feature of metal oxide chemistry is the unusual electronic and chemical behaviour of Cu(I) and Ag(I): a case in point is that detailed understanding of Cu–O bonding is essential to the theory of high-temperature copper oxide superconductors. Both cations are usually coordinated in a linear fashion to two oxygens, particularly for Cu(I). In many compounds, the Cu(I) and Ag(I) cations also adopt close-packed (and related) configurations with short metal–metal distances that are strongly suggestive of the occurrence of metal–metal bonding1, 2 despite their formal nd 10 configuration. Such observations have been explained3, 4 by invoking the participation in bonding of electronic orbitals of higher principal quantum number—that is, (n + 1)s and (n + 1)p—accompanied by the creation of d-orbital holes on the metal ion. To test this hypothesis, we have used a recently developed method of quantitative convergent-beam electron diffraction5 combined with X-ray diffraction to map the charge-density distribution in the simple oxide Cu2O, the results of which we then compare with electronic-structure calculations. We are able to image directly the d holes on the copper atoms, and also demonstrate the existence of Cu–Cu bonding in this compound.

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