Enhancement of optical absorption and dispersion characteristics of nanocrystalline In2Se3 films: impact of γ-ray irradiation

Abstract

Thermal evaporation was used to deposit In2Se3 thin films with a thickness of 276 nm on different glass and quartz substrates under vacuum. The 60Co rays were used to irradiate thin films at dosages of 10, 20, 30, 40, and 50) kGy. X-ray Diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the crystalline and morphological structure of In2Se3 thin films, respectively. The results revealed that powder has a polycrystalline structure, whereas pristine and irradiated thin films are amorphous. The computed absorption coefficient indicates that direct transition is allowed for the as-deposited and γ-irradiated thin films, and the value of the measured energy gaps increases when the dose is increased from 10 to 50 kGy. Using single-oscillator models to obtain the dispersion parameters, the spectral dependency of the refractive index in the higher wavelength area was studied. The effect of irradiation on dielectric constants and dispersion characteristics suggests that the examined films are highly sensitive to appropriate irradiation dose. The nonlinear optical susceptibility has improved, making it appropriate for a variety of device applications.