Staebler-Wronski effect in hydrogenated amorphous silicon

Abstract

A scenario for the Staebler-Wronski (SW) photoconductivity σ(t) in hydrogenated amorphous silicon is modeled by the kenetics of the dangling bond density d(t). Hydrogen atoms (H) on Si---Si bonds are induced to hop by the illumination-triggered breakage of weak neighboring bonds (d(t) ~ t^1/3). The breakage leads to enhanced H diffusion over disordered barriers, which breaks further bonds, inducing further diffusion and causing a d(t) rise as a stretched exponential. d(t) then saturates to a temperature-dependent value, as breakage is limited by bond-pair thermal healing. Above a temperature T_SW, thermal bond-pair healing beats breakage, and σ(t) recovers.