Beta-Ray irradiation effect on optical and dielectric properties of InSe film

In this study, the effects of β-ray radiation on the optical and dielectric properties of InSe thin film were investigated using a Sr-90 β-source at doses of 0, 5, 10, and 20 kGy. To analyze the optical properties of the film, the transmittance (T) and absorbance (A) measurements were performed using a UV-Vis spectrophotometer in the 500–1000 nm spectral range. Optical and dielectric parameters including absorption coefficient, extinction coefficient, optical band-gap, refractive index, dielectric constant and optical conductivity were obtained from T and A data. As the radiation dose increased, transmittance increased while absorbance decreased. Under β-irradiation, these dose-dependent changes confirm the occurrence of defect formation, band rupture, and local atomic rearrangements. The band-gap energy (Eg) InSe film, which has the direct optical transition, was determined from Tauc plot. The Eg values were found in the range of 1.67 eV (0 kGy) to 1.59 eV (20 kGy), that is, they were decreased with increasing radiation dose. These results demonstrate that the optical response of the InSe film is strongly dependent on both wavelength and irradiation dose.