Gamma irradiation effect on the structural and optical properties of nanostructured InSe thin films

Thin films of InSe were prepared by thermal evaporation technique under a vacuum of 10− 4 Pa. The effect of γ-irradiation on the structure, and the optical parameters were investigated. The analysis of XRD of InSe proved that the non-irradiated films have an amorphous background with a preferential orientation in the (002) direction. The crystallite size was calculated and its value increases while increasing the γ-irradiation. The optical parameters were obtained using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light at the wavelengths range 200–2500 nm. The type of optical transition was found to be an indirect allowed transition, and it is found that the band gap increases while increasing γ-irradiation. This post-irradiation increase in the band gap was interpreted in terms of bond rearrangements and changes in the microstructure of these films. On the other hand, the dispersion parameters of InSe films were decreased while increasing the irradiation dose.