Structural, morphological and optical characterizations of spray pyrolyzed nickel oxide thin films

Abstract

A simple spray pyrolysis technique was used to prepare thin nickel oxide films on glass substrates at different substrate temperatures (350 °C, 400 °C, and 450 °C). Hydrated Nickel Acetate (Ni(CH3COO)2·4H2O) salt solution was used as a precursor to producing these thin films. The structural properties of the films were characterized by X-ray Diffraction (XRD) spectroscopy. The XRD curve confirms that the films were crystalline, and their preferred growth orientation was along the (111) plane. The values of the lattice parameter, dislocation density, and microstrain were changed with the temperature of the substrate. Scanning Electron Microscope (SEM) micrographs of the surface of the prepared thin films showed uniform morphology with nanorings. A UV-visible Spectrophotometer was used to detect absorption and transmission spectra in the spectral region of 300 nm–900 nm. The films deposited at 400 °C and 450 °C have 80% transparency in the visible wavelength region, while the films deposited at 350 °C have lower transparency. The optical bandgap of the films was varied with substrate temperatures and the values were from 3.55 to 3.65 eV. Other optical metrics, including extinction coefficient, refractive index, optical conductivity, and electron energy loss functions, were also affected by substrate temperature.