Indium phosphide/cadmium sulfide thin-film terrestrial solar cells. Quarterly report No. 4, July 1--September 14, 1977
Indium phosphide/cadmium sulfide solar cells with AM2 efficiencies up to 7% were prepared by the deposition of CdS on single crystals of InP. When an intermediate layer of n-type InP was deposited by the planar reactive deposition (PRD) technique, 3% efficiencies were obtained. Reduced efficiencies were obtained when an intermediate layer of p-type Mn-doped InP was used as the light-absorbing layer. Manganese, acting as a deep center at 0.25 eV and introduced in concentrations of about 10/sup 18/ cm/sup -3/, may act as recombination and tunneling centers, thus limiting the efficiency of the cells. These results suggest that, to improve cell efficiency, either the Mn doping must be reduced or the purity of films must be improved. Methods of improving the purity of the films are suggested. Incorporating Zn as a dopant in the form of diethylzinc is proposed to provide a shallow center to replace Mn. An evaluation of thin films of InP prepared by PRD onto thin films of CdS and InP and sapphire substrates indicated that the InP grain boundaries are n-type, which results in intolerable high current paths through all-thin-film polycrystalline cells. Incorporating Zn as a dopant by diethylzinc is also proposed to provide a graded p to p/sup +/ structure, which would block the current at the grain boundaries. A recently implemented chemomechanical polishing technique has yielded smooth surfaces and complete coverage over single crystals of CdS.
- Research Organization:
- Hughes Research Labs., Malibu, Calif. (USA)
- DOE Contract Number:
- EY-76-C-04-3717
- OSTI ID:
- 5219186
- Report Number(s):
- ALO/3717-1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
CADMIUM SULFIDE SOLAR CELLS
FABRICATION
CRYSTAL DOPING
DEPOSITION
EFFICIENCY
GRAIN BOUNDARIES
INDIUM PHOSPHIDES
MONOCRYSTALS
CRYSTAL STRUCTURE
CRYSTALS
DIRECT ENERGY CONVERTERS
INDIUM COMPOUNDS
MICROSTRUCTURE
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PNICTIDES
SOLAR CELLS
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture