STAEBLER-WRONSKI EFFECT IN HYDROGENATED AMORPHOUS-SILICON

A scenario for the Staebler-Wronski (SW) photoconductivity sigma(t) in hydrogenated amorphous silicon is modeled by the kinetics of the dang ling bond density d(t). Hydrogen atoms (H) on Si-Si bonds are induced to hop by the illumination-triggered breakage of weak neighboring bond s (d(t) similar to t(1/3)). The breakage leads to enhanced H diffusion over disordered barriers, which breaks further bonds, inducing furthe r diffusion and causing a d(t) rise as a stretched exponential. d(t) t hen 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 sigma(t) recovers.