Thermally stimulated currents in a-Si: H

Abstract

Measurements of thermally stimulated currents (TSC) in hydrogenated amorphous silicon (a-Si: H) are found to show two peaks, at T ∼ 120 K and T ∼ 300 K respectively. The 300 K peak is resolved using two almost identical samples in a bridge configuration; from heating-rate and step-heating analyses it appears to arise from states near the Fermi level. The low-temperature peak reduces after light soaking (Staebler-Wronski effect) and is ascribed to states in g(E) near 0·16 eV. It is argued that a peak in the initial occupancy of states, caused by the product of a fast-rising g(E) and an exponentially decaying occupancy function f(E) in this region, may be responsible for this TSC peak, and may not necessarily imply any structure in g(E).