Optical and photoconductivity properties of Mn doped nanocrystalline PbS thin films deposited by chemical bath deposition method

Abstract

Mn doped nanocrystalline PbS thin films were deposited onto glass substrates by chemical bath deposition (CBD) method. All the deposited thin films were found to be crystalline having cubic phase structure. The optical properties of the Mn doped nanocrystalline PbS thin films have been studied. They have high absorbance in the UV-visible region. The linear nature of (αhν)2 vs (hν) plots of PbS thin films confirmed that the transition is direct and the optical band gap energy of PbS films is found to increase from 1.90 eV to 2.28 eV with decreasing crystallite size from 21 nm to 11 nm and the optical band gap values are higher than the bulk value (0.40 eV). The optical band gap of Mn doped PbS films are found to increase with increase in dopant concentrations. The Photoconductive rise time and decay time determined from the prepared films are found to decrease with increase in doping concentrations.