Cuprous oxide--indium--tin oxide thin film photovoltaic cells
We studied thin films of cuprous oxide deposited on glass coated with transparent conducting indium--tin oxide (ITO) films. The deposition of both Cu/sub 2/O and ITO was made by rf sputtering in an Ar/O/sub 2/ gas mixture. For the deposition of Cu/sub 2/O a pure copper target was used and ITO films were deposited from a disk target, the halves of which were made of Sn and In, respectively. This allows variation of the stoichiometry of the deposited ITO film by changing the position of the substrate glass beneath the Sn/In target. X-ray diffraction of Cu/sub 2/O films indicates the typical pattern of amorphous material. We were able to produce Cu/sub 2/O films of different stoichiometry by varying the O/sub 2/ to Ar ratio during rf sputtering. The maximum resistivity of the films corresponds to an ideal stoichiometry of Cu/sub 2/O. An activation energy of 0.55 eV found from thermostimulated conductivity is related to excess Cu vacancies. The band gap found from the spectral dependence of the photovoltaic effect is 2.0 eV. The composition of ITO films was studied by Auger analysis and can be described as a variable composition mixture of SnO/sub 2+x/ and In/sub 2/O/sub 3+y/. To produce an Ohmic electrode, gold was evaporated on the top of the Cu/sub 2/O film and hence the resulting structure of the photocell could be specified as ITO--Cu/sub 2/O--Au, for which we propose a barrier band diagram. We studied the photovoltaic characteristics of the fabricated photocells under an incandescent lamp with approx. =100 mW/cm/sup 2/ output. The open-circuit voltage and short-circuit current of our cells were about 20--90 mV and 50 ..mu..A/cm/sup 2/, respectively, and some dependence of the output characteristics on the composition of ITO film was observed. Conversion efficiency for thin films Cu/sub 2/O/ITO cells was found to be substantially lower than for Cu/sub 2/O/Cu Schottky barrier cells. This is tentatively attributed to small diffusion lengths and/or presence of interface recombination centers.
- Research Organization:
- Department of Electronics, Tokyo Denki University, Chiyoda-Ku, Tokyo 101, Japan
- OSTI ID:
- 6107492
- Journal Information:
- J. Appl. Phys.; (United States), Vol. 54:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COPPER OXIDE SOLAR CELLS
ELECTRIC CONDUCTIVITY
FABRICATION
COPPER OXIDES
SPUTTERING
INDIUM OXIDES
TIN OXIDES
ACTIVATION ENERGY
AMORPHOUS STATE
ARGON
COPPER
DEPOSITION
ENERGY GAP
EXPERIMENTAL DATA
FILMS
OXYGEN
RF SYSTEMS
STOICHIOMETRY
THICKNESS
X-RAY DIFFRACTION
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
DATA
DIFFRACTION
DIMENSIONS
DIRECT ENERGY CONVERTERS
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY
EQUIPMENT
FLUIDS
GASES
INDIUM COMPOUNDS
INFORMATION
METALS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
RARE GASES
SCATTERING
SOLAR CELLS
SOLAR EQUIPMENT
TIN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
140501* - Solar Energy Conversion- Photovoltaic Conversion