Influence of γ-irradiation dose on the structure, linear and nonlinear optical properties of BiI3 thick films for optoelectronics

Abstract

In this study, 900 nm of BiI3 thick films were prepared using the thermal evaporation technique. There were exposed to different doses (0, 50, 100, 150, 200, 250, and 300 kG) of γ-radiation. The microstructure properties (Crystallite size and lattice strain) were calculated in terms of Scherrer’s equation. With increasing γ-radiation doses, the Crystallite size increases, Both the refractive index and the film thicknesses have been calculated using Swanepoel's method. The optical band gap was measured in terms of transmittance and reflection spectrum in the high region of the absorption. The possible optical transition in the as-deposited and treated films are found to allow direct transition with energy gap increases with increasing γ-radiation doses. Dielectric constant, volumeenergy-loss function (VELF), and surface-energy-loss function (SELF) for as-deposited films were discussed in terms of γ-radiation doses. The change in optical parameters has been interpreted in terms of the change in microstructure parameters. In terms of changes in energy gap and optical constants as a function of γ-radiation doses, BiI3 thick films are recommended to use in optical devices and solar cells.