Thermal relaxation of the electric conductivity in amorphous silicon-germanium alloys

Abstract
We report the first observation of the effect of thermal annealing and quenching on the dark and photoelectric conductivities in hydrogenated and fluorinated amorphous silicon-germanium alloys (a-Si,Ge:H,F). A reversible glasslike transition of the dark and photoconductivities was observed and was used to estimate a freeze-in temperature of about 140 °C for alloys with optical gaps of about 1.4 eV. This observation suggests thermal-equilibrium processes of defect states in the alloys. The possible implication to solar-cell performance is discussed.