Synthesis and characterization of undoped and strontium doped ZnO thin films

Abstract

In the current work, un-doped Zinc Oxide (ZnO) and Strontium (Sr) doped ZnO (SZO) thin films have been prepared by sol-gel spin coating technique on glass substrates to carry out irradiation studies to look for radiation induced modifications, especially in structural and optical properties. The films were coated after 24 h of aging, pre-heated at 100 °C and annealed at 500 °C for an hour. The modes of crystallization, structural properties and morphologies have been investigated and found to be polycrystalline in nature with hexagonal phase having (002) preferential orientation. The typical crystallite was also estimated and found to be around 20–30 nm. As the introduction of dopant increased, the lattice strains of the ZnO film also increased and are found to lie in the range of 21.19 nm to 38.16 nm. The X-ray diffraction studies indicated that the films exhibit single phase hexagonal wurtzite structure. All the peaks for the films, therefore, are indexed to the (100), (002), and (101). The optical properties of the films found to be varied significantly with the doping element concentrations. Further, the optical transmittance and optical band gap have also shown notable changes due to doping. The measured transmission spectra indicated that the films are transparent in the visible region.