Transient Photoconductivity of Amorphous Se85-XTe15Bix Thin Films

Abstract

Photoconductive properties of a-Se_85-xTe₁₅Bi_x (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 (E_g) as determined from Tauc extrapolation method is found to follow the similar trend as that of dark activation energy (ΔE_d) except for Bi = 1 at. %. The decay of photocurrent with time is also studied for the samples. The differential life time τ_d as determined from the decay of photocurrent w.r.t. time is found to increase with increasing Bi content.