Light-Induced Metastable Changes in a-SiSx:H

Abstract

ABSTRACTMetastable light-induced increases in the dark conductivities of a-SiSx:H alloys are explained as photo-activation of hydrogen-passivated sulfur donor sites. For a sulfur concentration (sulfur-to-silicon ratio) of 5.6 × 103 the excess dark conductivity as a function of illumination temperature is thermally activated with an activation energy of 0.72 eV. When the sulfur concentration is 3.3 × 102, the temperature dependence is very weak. This dramatic difference in the temperature dependence of the creation of increased dark conductivity is explained by a lowering of the annealing temperature for the metastable changes as the sulfur concentration increases. We discuss the influence of this new metastability on the possibility of obtaining more stable films.