Photocurrent collection in a Schottky barrier on an amorphous silicon-germanium alloy structure with 1.23 eV optical gap

We report the result of voltage-dependent photocurrent collection measurements in Pd Schottky barriers on an undoped a-Si,Ge:H,F multilayer alloy structure with an effective optical gap of 1.23 eV. The hole mobility-lifetime product (μτ)p, extracted from a fit of the voltage dependence of the photocurrent to the Hecht expression, is 7×10−9 cm2 V−1. Our result is an important indication that it is possible to produce the low-gap a-Si,Ge:H,F alloys with the optoelectronic characteristics needed for efficient tandem solar cells.