Ni-doping effect on the structural and optical properties of sprayed ZnO thin films

Nickel-doped ZnO thin films with different Ni contents (0 - 15%) were deposited on glass substrate at 350⁰C by a spray pyrolysis technique. 0.1 M solutions of zinc acetate and nickel sulphate were used as the precursors with air as the carrier gas. The effect of Ni-doping on the structural and optical properties of the layers was evaluated using appropriate techniques. The X-ray diffraction studies revealed that nickel atoms were successively incorporated into ZnO host matrix without forming any detectable secondary phase. All the grown films were polycrystalline with the (002) plane as the preferred orientation and the peak position shifted towards higher diffraction angle with the increase of doping content in the films. The films had hexagonal shaped grains and the evaluated grain size varied in the range of 20 - 48 nm. The optical studies revealed a decrease of transmittance with the increase of Ni-doping content in the films and the evaluated energy band gap was found to be direct that decreased from 3.32 eV to 3.05 eV.