Photoelectrical properties of Te-substituted Sn-Sb-Se Semiconducting thin films

Abstract

Thin films of Sn10Sb20Se70−XTeX (0≤X≤8) composition were deposited using thermal evaporation technique. The prepared films were found amorphous by X‐ray diffraction studies. Surface roughness was found to be ∼2 nm and grain size ∼30 nm from SPM studies. The dark conductivity measurements showed thermally activated conduction. Photoconductivity measurements showed no maxima in the measured temperature regime and thus materials belong to type II photoconductor. The dc‐activation energy for photoconductivity ΔEph has values smaller than dc‐activation energy for dark conductivity ΔE. Intensity variation of photocurrent obeys power law with exponent γ∼0.56–0.64 revealing the dominant bimolecular recombination mechanism. Transient photoconductivity measurement showed that the initial rise and decay of photocurrent becomes slow with tellurium content in the sample. The decay process after initial decay was found to be non‐exponential and described as differential life time of charge carrier which decreases with tellurium content in the sample.