Effect of low dose-rate industrial Co-60 gamma irradiation on ZnO thin films: Structural and optical study

The effect of low-dose rate gamma rays irradiation on ZnO thin films of different thicknesses has been studied. Preferentially oriented (002) ZnO thin films have been deposited on Si (100) and glass substrates using radio frequency magnetron sputtering. ZnO films with c-axis-oriented Wurtzite structure were obtained at room temperature. ZnO films with thickness of 200 nm and 600 nm were prepared and studied. The prepared films were irradiated using1.25-MeV gamma beam emitted from Cobalt sources (Co-60) with two different doses (2and 4 kGy) and the effect of the gamma irradiation on the optical and structural properties of the ZnO films was examined. The photoluminescence PL intensity was found to increase with the increasing of the irradiation dose in both thin and thick films. This finding allows improving the scintillation output signal of the material while keeping grain size unchanged if low dose rate irradiation is used, as X-ray diffraction patterns showed. Raman spectrum correlates with XRD results. The band gap extracted by UV transmittance spectrum was also identified.