Continuous decay of drift mobility in intrinsic a-Si:H and a-SiC:H upon light soaking investigated by the photomixing technique

Abstract

The photoconductivity, electron lifetime, and electron drift mobility in intrinsic hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon carbide (a-SiC:H) while light soaking were determined using a photomixing technique. In addition to the decay of the photoconductivity and electron lifetime, continuous decay of the electron drift mobility was found during the light soaking process, which reveals that the light-induced metastable defects of the Staebler–Wronski effect results in scattering as well as recombination of charge carriers. The drift mobility decreased by a factor of 2 for 20 h light soaking at 2.5 sun intensity. Experimental data were fitted to a stretched exponential law. Different stretched-exponential parameters for photoconductivity, lifetime, and drift mobility were obtained, which indicates the production of defects with different generation kinetics upon light soaking.