Photocurrent enhancement in light-soaked chalcogenide glasses

Abstract

Photocurrent changes with light soaking have been studied in amorphous ${\mathrm{As}}_{2}{\mathrm{S}(\mathrm{S}\mathrm{e},\mathrm{T}\mathrm{e})}_{3}$ and Se and crystalline ${\mathrm{As}}_{2}{\mathrm{S}}_{3}$ and Se at 10--300 K. In the chalcogenide glasses the photoconductive degradation occurs at 300 K, while at low temperatures photocurrents in subband-gap spectral regions increase with light soaking. In the crystalline samples, no such changes are detected. The photoconductive enhancement appears to be related to the photoinduced midgap absorption, and the microscopic mechanism is discussed in a unified way. The observations are also compared with those in the Staebler-Wronski effect in amorphous Si:H films.