50 MeV Li- and 80 MeV Ni- ions induced modification in ZnO cauliflower like structure: Structural, optical and electrical studies

In this work, ZnO has been synthesized by co-precipitation method and mixed with 0.5 % of polyvinyl alcohol for the preparation of thin film. These ZnO thin films have been irradiated with lithium (Li) and nickel (Ni) beams of energy 50 MeV and 80 MeV respectively, at different fluence. XRD pattern reveals that the crystallite size varies from 41 nm to 21 nm for Li-irradiated ZnO and to 16 nm for Ni irradiated ZnO compared to pure ZnO. From UV–Visible spectroscopy, the bandgap of Li-irradiated ZnO to a fluence of 5 × 10¹² ions/cm² is found to be 3.20 eV However, for Ni-irradiated ZnO bandgap varies from 3.11 to 3.08 eV Upon investigation of PL spectra, it has been observed that broadening in the defect region is observed on increasing the Li fluence. However, Ni-ions lead to enhancement of defects with increase in fluence. Electrical properties reveal the enhancement of current in order of three for both the ions irradiated ZnO. Li irradiation leads to reduction in resistivity whereas Ni irradiation leads to the enhancement in ZnO resistivity. This suggests that the ion beam induced modification in ZnO lattice could be useful for tuning the optoelectronic properties & can be used for organic light emitting diodes.