Enhancement of photosensitivity of thermally evaporated crystalline PbS thin films by low energy oxygen ions implantation

Abstract

This study presents the effect of low energy (120 KeV) O-ions implantation on the photosensitivity of PbS thin films by vacuum thermal evaporator (VTE). The crystallite size (D) of PbS films decreased from 32.8 nm to 17.4 nm and the bandgap (E g) increased from 1.61 eV to 1.76 eV as the fluence increased from 0.5 × 1016 ions cm−2 to 1.5 × 1016 ions cm−2. The PL spectra of O-ions implanted PbS thin films showed a dominant peak at 381 nm regardless the fluence of implantation. The photocurrent sharply increased by the implantation of O-ions (0.5 × 1016 ions cm−2) due to the creation of ‘shallow traps’ in the forbidden gap of PbS thin films under illumination of visible light (100 mW cm−2). The highest photosensitivity of O-ions implanted PbS thin films was observed due to the creation of proper traps for the photoconduction for the particular dose of 0.5 × 1016 ions cm−2.