Optoelectronic and electrochemical properties of nickel oxide (NiO) films deposited by DC reactive magnetron sputtering

Nickel oxide (NiO) thin films were deposited onto glass substrates by the DC reactive magnetron sputtering technique. The as-deposited films were post-annealed in air at 450–500 °C for 5 h. The effect of annealing on the structural, microstructural, electrical and optical properties were studied by X-ray diffraction (XRD), atomic force microscope (AFM), four-probe resistivity measurement and UV-vis spectrophotometer. XRD studies indicated cubic structure with a lattice parameter of 0.4193 nm. The band gap of the films was found to be 3.58 eV. Fourier transform infrared (FTIR) studies indicated a broad spectrum centered at 451.6 cm−1. Photoluminescence studies exhibited room temperature emission at 440 nm. Cyclic voltammetry studies in 1 M KOH solution revealed the electrochromic nature of the NiO films prepared in the present study.