8Â MeV electron beam induced modifications in the structural, optical and electrical properties of Al doped ZnO thin film

The influence of high energy (8 MeV) electron irradiation, with different dose rates (0 kGy, 1 kGy, 5 kGy, 10 kGy), on the structural, optical and electrical properties of sol-gel spin coated Al-doped ZnO (AZO) thin films have been studied. The X-ray diffraction curve displays the coating of c-axis oriented films under the state of compressive stress. A further analysis reveals that the interstitial sites were occupied by the Al in AZO upon electron irradiation. With the increase in irradiation dose, the energy gap of the film shows a redshift due to the enhanced localized states in the band structure. An increment in the values of refractive index of the films after irradiation is attributed to their enhanced optical density. Steady state luminescence spectra reveal the presence of zinc interstitial and oxygen interstitial defects in the irradiated film. Time-resolved photoluminescence (PL) measurement shows that the dominant defect related recombination mechanism in the irradiated films is arising due to the increased dangling bonds and defect related transitions. The increase in sheet resistance upon electron irradiation is attributed to decreasing carrier concentration in the film. The irradiated AZO film may be useful for space applications and in the radiation environment.