Transient Photoconductivity of Amorphous Se85-XTe15Bix Thin Films

Abstract

Photoconductive properties of a-Se85-xTe15Bix (where x = 0, 1, 2, 3, 4, 5) glassy thin films prepared by vacuum evaporation technique are recorded at room temperature (303 K) using Keithley 6487 picoammeter. Temperature dependent dark conductivity is studied in the temperature range 303-333 K and it shows that conduction for the studied composition is through an activated process, having single activation energy. Optical band gap (Eg) as determined from Tauc extrapolation method is found to follow the similar trend as that of dark activation energy (ΔEd) except for Bi = 1 at. %. The decay of photocurrent with time is also studied for the samples. The differential life time τd as determined from the decay of photocurrent w.r.t. time is found to increase with increasing Bi content.