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U.S. Department of Energy
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Gallium arsenide thin films on tungsten/graphite substrates: Phase II. Quarterly project report No. 1, September 1, 1977--November 30, 1977

Technical Report ·
OSTI ID:5014759

Efforts have been directed to the deposition and characterization of gallium arsenide films on graphite and tungsten/graphite substrates and the fabrication and evaluation of solar cells on these substrates. Sulfur doped gallium arsenide films have been deposited on graphite substrates at 725 to 825/sup 0/C, and their structural and electrical properties investigated. The gallium arsenide/graphite interface has been found to be rectifying in all cases studied. However, at high doping levels, the voltage drop across the gallium arsenide/graphite interface is sufficiently low for solar cell purposes. Solar cells of the configuration Ag/n-GaAs/n/sup +/-GaAs/graphite have AM1 efficiencies (without AR coating) of about 2.7%. The deposition of gallium arsenide films on tungsten/graphite substrates has been continued with emphasis on the oxidation of gallium arsenide. Both argon-oxygen and oxygen-water vapor mixtures have been used as oxidizing agents. Using titanium dioxide as the anti-reflection coating, an Au/n-GaAs/n/sup +/-GaAs/W/graphite solar cell has an AM1 efficiency of 5.6%; however, its characteristics degraded under continuous illumination due presumably to trapping effects. Several p-n junction gallium arsenide solar cells have been prepared on tungsten/graphite substrates. The highest open-circuit voltage obtained was about 250 mV; however, the short-circuit current was very low.

Research Organization:
Southern Methodist Univ., Dallas, Tex. (USA)
OSTI ID:
5014759
Report Number(s):
SAN-1284-1
Country of Publication:
United States
Language:
English