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Gallium arsenide thin films on tungsten/graphite substrates: Phase II. Topical report: thin film gallium arsenide solar cells on tungsten/graphite substrates

Technical Report ·
OSTI ID:6299199

The use of a thin film of gallium arsenide on a low cost substrate appears to be a promising approach for the fabrication of low-cost high-efficiency solar cells. Gallium arsenide films have been deposited on tungsten/graphite substrates at 775/sup 0/C by the reaction of gallium, hydrogen chloride, and arsine in a gas flow system. The deposited films are essentially polycrystalline with an average crystallite size of about 10 ..mu..m. Without intentional doping, the deposited films are n-type with carrier concentrations in the range of 2 x 10/sup 16/ to 8 x 10/sup 16/ cm/sup -3/ at room temperature. N-type gallium arsenide films of higher dopant concentrations can be readily deposited by using hydrogen sulfide as a dopant. The MOS approach has been used for the preparation of solar cells. After the successive deposition of n/sup +/- and n-gallium arsenide films on a tungsten/graphite substrate, the surface of the film was oxidized in situ with an argon-oxygen mixture and in some cases, followed by a water vapor treatment at room temperature. The gold barrier and silver grid contacts were applied by evaporation. An antireflection coating of titanium dioxide was deposited at 80 to 100/sup 0/C by the hydrolysis of tetraisopropyl titanate in an argon atmosphere. A number of large area (6 to 9 cm/sup 2/) solar cells have been prepared, and the best cells have an AM1 efficiency of about 5.5%.

Research Organization:
Southern Methodist Univ., Dallas, TX (USA)
DOE Contract Number:
AC03-76SF01284
OSTI ID:
6299199
Report Number(s):
DOE/SF/01284-T3; ON: DE81027717
Country of Publication:
United States
Language:
English