Physical Investigations on ZnO:Ni Layers Deposited by Spray Pyrolysis

Abstract

Nickel-doped ZnO (ZnO:Ni) layers have been deposited on glass substrates by a spray pyrolysis method using zinc acetate and nickel sulphate as precursors. The layers were grown at different substrate temperatures, Ts, that vary in the range 250–350°C. During deposition, the precursor concentration and Ni-doping content were maintained constant at 0.1 M and 10%, respectively. The X-ray diffraction (XRD) analysis showed that all the layers were polycrystalline in nature with the (002) plane as the preferred orientation and exhibited hexagonal wurtzite structure. A sharp increment in the intensity of predominant peak with the substrate temperature was observed consistently that indicated an improvement in the crystallinity of the layers. The Raman studies confirmed the hexagonal wurtzite crystal structure of ZnO and indicated defect states. The X-ray photoelectron spectroscopy (XPS) studies revealed the characteristic peaks of the elements involved in the films and their ionic states. The optical transmittance of the films was higher than 80% and the evaluated energy band gap decreased from 3.17 eV to 3.13 eV with the increase of substrate temperature.