Study of Optical and Structural Properties of NiO Thin Films Prepared by Chemical Spray Pyrolysis (CSP) Method

In this study, NiO thin films with molarity of 0.1 M have been successfully deposited on glass substrates by chemical spray pyrolysis (CSP) technique at a substrate temperature of 400°C and a deposited thickness of about 350 nm. The structural and optical properties of these films have been studied using Ultraviolet-visible (UV-Visible) spectroscopy and X ray diffraction (XRD). The absorbance and transmittance spectra have been recorded in the wavelength range of 300-900 nm in order to study the optical properties. The optical energy gap for allowed direct electronic transition was calculated using Tauc’s equation. It is found that the band gap is equal to 3.58 eV for the prepared thin films. The optical constants, including absorption coefficient, were also calculated as a function of photon energy. Refractive index and extinction coefficient for the prepared thin films were estimated as a function of wavelength in the wavelength range 300-900 nm. The XRD results showed that the studied films are polycrystalline in nature with a cubic structure and a preferred orientation along (111) plane. The average crystallite size of the film was estimated for (111) direction by Scherrer formula and was equal to ~ 10nm.