Influence of high gamma radiation on the optical and photoluminescence characteristics of ZnO thin films

Abstract

In this study, the researchers attempt to investigate the effect of irradiation of gamma doses in the range 25–150 kGy on the optical properties of sputtered ZnO thin films. The samples have a hexagonal wurtzite structure. The optical properties of the samples, such as the absorbance, transmittance, and reflectance, have been studied as a function of γ- irradiation doses. Several optical parameters, such as refractive index, optical energy gap, Urbach energy, oscillatory energy, dispersion energy, oscillator strength, and dielectric constant have been found to be affected by changing the γ- irradiation doses. The refractive index dispersion curve of the γ-irradiated and non-irradiated ZnO thin films meet the criteria of the single-oscillator model. The room temperature photoluminescence spectra of the samples under excitation 400 and 437 nm showed green emission nearly at 2.597 and 2.559 eV, and yellow emission approximately at 2.15 eV. The green emission bands can be attributed to a transition from CB to VZn −2 and −1 respectively, while the yellow emission band can be attributed to a transition between a shallow donor and a deep level. © 2020 Informa UK Limited, trading as Taylor & Francis Group.