Thin-film gallium arsenide homojunction solar cells on recrystallized germanium and large-grain germanium substrates

Abstract

Polycrystalline gallium arsenide films of 10-μm thickness deposited on tungsten/graphite substrates by the reaction between gallium, hydrogen chloride, and arsine have been used for the fabrication of thin-film homojunction solar cells. The major problem associated with polycrystalline gallium arsenide thin-film cells is the grain-boundary shunting effect. In order to prepare solar cells with conversion efficiency higher than 10%, gallium arsenide films with large grains are necessary. Unlike gallium arsenide, germanium films can be easily recrystallized to enhance the grain size. Thin-film gallium arsenide solar cells of the p+/n configuration with an AM1 efficiency of about 10% have been prepared using recrystallized germanium and large-grain germanium substrates.