Characterization and properties of NiO-ZnO nanocrystalline thin films on glass substrates deposited by SILAR technique

Nanocrystalline thin films of pristine ZnO and NiO, as well as their composites NiO-ZnO have been deposited on glass substrates with varying percentages of individual components using the successive ionic layer adsorption and reaction (SILAR) technique. The morphology of the deposited nanocomposite films were characterized by scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDX). X-ray diffraction (XRD) analysis and Raman spectra revealed phase identification of zinc oxide (ZnO) and nickel oxide (NiO). Fourier transform infra-red (FTIR) spectroscopy technique provides specific important structural and functional information of the prepared samples. UV-Visible spectroscopy revealed the transmittance increased with the increase in ZnO while the abrupt drop in transmittance shifted towards lower wavelength as NiO content increased. Photoluminescence spectroscopy (PL) was used to study the optical properties providing evidence for several types of defects in the as grown nanostructures. The optical properties varied with the mixing proportion of ZnO and NiO. Increasing percentage of ZnO in the composite films induced red shift in the optical energy band gap in the range (3.51-3.12eV) and induced decline in electrical resistivity.