Synthesis, evaluation and defect compensation of tetrahedral glasses as possible solar cell materials. Final report, February 1, 1979-April 30, 1980
The work reported was directed towards evaluation of new amorphous compounds for application in solar cells. The ternary A/sup II/B/sup IV/C/sub 2//sup V/ chalcopyrite systems were selected because of their inexpensive constituent elements and tetrahedral geometry. Polycrystalline samples of the ternary arsenides with Cd and Zn as the group II element and Ge, Si, Sn as the group IV element were synthesized. Thin films were deposited by vacuum evaporation of the bulk ternary arsenides. The stoichiometries of the films were irreproducible and were usually deficient in the lower vapor pressure group IV element. Films made by evaporating polycrystalline ZnAs/sub 2/, which also has a tetrahedral bonding structure, had stoichiometries generally in the range from Zn/sub 3/As/sub 2/ to ZnAs/sub 2/. The former compound is formed by the decomposition of ZnAs/sub 2/ to Zn/sub 3/As/sub 2/ and As/sub 4/. The intermediate stoichiometries are thought to be mixtures of the decomposition products. Preliminary results from annealing of the films indicate that heat treatment produces the stoichiometries expected for one of the two forms of zinc arsenide. The as-deposited films are amorphous when the substrate temperature is kept below 100/sup 0/C. The a-ZnAs/sub x/ films were characterized. EDAX and Auger analysis showed that films were homogeneous in the plane of the substrate, but that some variation occurred in the depth profile of the films. This change in composition is consistent with the sample decomposition which occurs during the evaporation. The as-prepared films were p-type with room temperature resistivities on the order of 10/sup 2/-10/sup 4/..cap omega..-cm. Optical absorption measurements gave optical band gap values of 1.2 eV for a-Zn/sub 3/As/sub 2/ and 1.5 eV for a-ZnAs/sub 2/. The ZnAs/sub x/ films were photoconductive.
- Research Organization:
- EIC Corp., Newton, MA (USA)
- DOE Contract Number:
- AC03-79ET23039
- OSTI ID:
- 5358089
- Report Number(s):
- DOE/ET/23039-4; ON: DE82007333
- Country of Publication:
- United States
- Language:
- English
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Synthesis: evaluation, and defect compensation of tetrahedral glasses as possible solar cell materials. Quarterly technical progress report No. 1, February 1, 1979-April 30, 1979
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Related Subjects
ZINC ARSENIDES
ELECTRICAL PROPERTIES
OPTICAL PROPERTIES
VACUUM EVAPORATION
ABSORPTION
AMORPHOUS STATE
ANNEALING
CADMIUM ARSENIDES
CHEMICAL COMPOSITION
CRYSTAL DEFECTS
ENERGY GAP
FILMS
GERMANIUM ARSENIDES
PHOTOCONDUCTIVITY
STABILITY
STOICHIOMETRY
THICKNESS
ARSENIC COMPOUNDS
ARSENIDES
CADMIUM COMPOUNDS
CRYSTAL STRUCTURE
DIMENSIONS
ELECTRIC CONDUCTIVITY
EVAPORATION
GERMANIUM COMPOUNDS
HEAT TREATMENTS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PNICTIDES
ZINC COMPOUNDS
140501* - Solar Energy Conversion- Photovoltaic Conversion