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

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 × 10 16 ions cm −2 to 1.5 × 10 16 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 × 10 16 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 × 10 16 ions cm −2 .