Influence of Gamma Radiation on the Linear-NonLinear Optical Properties of Te15Sn2.5Se82.5 Thin Film

The microstructure, optical properties, and γ-irradiation effects on Te15Sn2.5Se82.5 chalcogenide glass thin films were investigated. The absence of crystallite peaks in the X-ray diffraction XRD patterns for the pristine and γ-irradiated thin films indicated that the film was amorphous as manufactured. However, after gamma irradiation, several peaks appeared on the XRD sample, indicating the enhancement of a characteristic polycrystalline structure in the films. The transmittance values of the pristine and the irradiated films are very low, with maximum values ranging from 1.8 to 6.2% at a wavelength of 2500 nm. However, as the dose of gamma rays increases, the transmittance also increases, reaching maximum values of 45 to 62% at a wavelength of 2080 nm. Irradiation causes a modest decrease in the direct optical gap from 1.414 eV to 1.269 eV. The optical conductivity slightly increases with energy for as-prepared and irradiated films up to 100 kGy, then significantly rises with a higher gamma dose.