Transient Photoconductivity of Amorphous Se_(85-x)Te_(15)Bi_x Thin Films

摘要

Photoconductive properties of a-Se_(85-x)Te_(15)Bi_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 (ΔEd) 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.