Photoconductivity of amorphous As–Se–Sb thin films

Abstract

The present paper reports the effect of replacement of selenium by antimony on the steady state and the transient photoconductivity in vacuum evaporated amorphous thin films of As 30Se 70− x Sb x ( x = 2.5, 5, 7.5, 10, 12.5, 15 and 17.5 at.%). The composition dependence of the steady state photoconductivity at room temperature shows that the photoconductivity increases while the photosensitivity decreases with the increase in antimony content. The transient photoconductivity shows that the lifetime of the carrier decreases with increasing the light intensity. This decrease suggests that the photoconductivity mechanism in our samples was controlled by the transition trapping processes. Replacement of selenium by antimony results in a monotonic decrease in the band gap of As 30Se 70− x Sb x thin films. This behavior was interpreted on the basis of the chemical bond approach.