Development in understanding and controlling the Staebler-Wronski effect in a-Si : H

Hydrogenated amorphous silicon (a-Si:H) exhibits a metastable light-induced degradation of its optoelectronic properties that is called the Staebler-W ronski effect, after its discoverers. This degradation effect is associated with the relatively high diffusion coefficient of hydrogen and the changes in local bonding coordination promoted by hydrogen. Reviewed are the funda mental aspects of the interplay between hydrogen and electronic energy stat es that form the basis of competing microscopic models for explaining the d egradation effect. These models are tested against the latest experimental observations, and material and preparation parameters that reduce the Staeb ler-Wronski effect are discussed.