Structural and optical effects of low dose rate Co-60 gamma irradiation on PbS thin films

Thin films of lead sulphide (PbS) were grown on the Si (100) and glass substrates using the simple chemical bath deposition (CBD) method. The prepared films had the cubic structure at room temperature, and the thickness was 350 nm at a 120 min deposition time. In this work, the effect of low-dose rate gamma irradiation on the structural and optical characteristics of the prepared thin films was investigated. The PbS thin films were exposed at the National SSDL (Secondary Standard Dosimetry Laboratory) using gamma beam emitted from Co-60 source, the average energy of the photon beam was 1.25 MeV. Here, four different doses (1, 2, 3 and 4 kGy) were used and the dose rate was about 380 mGy/min. The changes on the optical and structural properties of the PbS films due to the gamma irradiation were evaluated. The results showed that the intensity of photoluminescence PL and the grain size decreased with increasing the radiation dose. This could be related to the changes in the crystalline structural during the experiment. In addition, the band gap obtained by the UV transmittance spectrum was confirmed with the results of XRD. These results could indicate the potential application for PbS film in microelectronic field.