Recrystallization of Ge for III-V photovoltaic substrates

Amorphous germanium (Ge) is RF sputtered onto 25 ¿m thick molybdenum (Mo) foils and recrystallized at 675 °C under an AsH
₃
environment. After annealing, the Ge is polycrystalline with grain boundary regions that range from 1 um
²
to 0.5 cm
²
. The polycrystalline surface behaves electrically much like that of commercial single crystal Ge. This polycrystalline Ge on thin Mo foil will serve as a substrate for a high efficient, high mass-specific-power, photovoltaic device.