Thin films of gallium arsenide on low-cost substrates. Final technical report, July 5, 1976-December 5, 1978
The MO-CVD technique was applied to the growth of thin films of GaAs and GaAl As on inexpensive polycrystalline or amorphous substrate materials (primarily glasses and metals) for use in fabrication of large-area low-cost photovoltaic device structures. Trimethylgallium, arsine, and trimethylaluminum are mixed in appropriate concentrations at room temperature in the gaseous state and pyrolyzed at the substrate, which is heated in a vertical reactor chamber to temperatures of 700 to 750/sup 0/C, to produce the desired film composition and properties. Studies of the properties of grain boundaries in polycrystalline GaAs films by the use of transport measurements as a function of temperature indicated that the grain boundary regions are depleted of majority carriers by a large density of neutral traps at the grain boundary interface, causing a barrier to majority carrier flow in the material. Schottky-barrier solar cells of approx. 3 percent efficiency (simulated AM0 illumination, no AR coating) were demonstrated on thin-film polycrystalline GaAs n/n/sup +/ structures on Mo sheet, Mo film/glass, and graphite substrates. Substantial enhancement of average grain size in polycrystalline MO-CVD GaAs films on Mo sheet was obtained by the addition of HCl to the growth atmosphere during deposition. Extensive investigation of polycrystalline thin-film p-n junctions indicated that the forward voltage of such devices is apparently limited to 0.5 to 0.6V. A laboratory-type deposition apparatus for the formation of TiO/sub 2/ antireflection (AR) coatings by pyrolysis of titanium isopropoxide was assembled and tested. Detailed analyses were made of the materials and labor costs involved in the laboratory-scale fabrication of MO-CVD thin-film GaAs solar cells. Details are presented. (WHK)
- Research Organization:
- Rockwell International Corp., Anaheim, CA (USA). Electronic Devices Div.
- DOE Contract Number:
- AC03-76ET20435
- OSTI ID:
- 6729266
- Report Number(s):
- SAN-1202-8
- Country of Publication:
- United States
- Language:
- English
Similar Records
Thin films of gallium arsenide on low-cost substrates. Quarterly technical progress report No. 8 and topical report No. 3, April 2-July 1, 1978
Thin films of gallium arsenide on low-cost substrates. Quarterly project report No. 1, July 5--October 2, 1976
Related Subjects
36 MATERIALS SCIENCE
GALLIUM ARSENIDE SOLAR CELLS
FABRICATION
GALLIUM ARSENIDES
CHEMICAL VAPOR DEPOSITION
ELECTRICAL PROPERTIES
GRAIN BOUNDARIES
ANTIREFLECTION COATINGS
CARRIER MOBILITY
COST
DESIGN
ELECTRIC CONDUCTIVITY
FILMS
GRAIN SIZE
MATHEMATICAL MODELS
P-N JUNCTIONS
POLYCRYSTALS
RESEARCH PROGRAMS
SCHOTTKY BARRIER DIODES
SEMICONDUCTOR JUNCTIONS
SUBSTRATES
TRAPS
VAPOR DEPOSITED COATINGS
ARSENIC COMPOUNDS
ARSENIDES
CHEMICAL COATING
COATINGS
CRYSTAL STRUCTURE
CRYSTALS
DEPOSITION
DIRECT ENERGY CONVERTERS
EQUIPMENT
GALLIUM COMPOUNDS
JUNCTIONS
MICROSTRUCTURE
MOBILITY
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
PNICTIDES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SIZE
SOLAR CELLS
SOLAR EQUIPMENT
SURFACE COATING
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture
360603 - Materials- Properties