Effect of oxygen partial pressure on the structural, optical and electrical properties of sputtered NiO films

Nickel oxide (NiO) thin films were deposited on glass substrates by dc reactive magnetron sputtering technique. The influence of oxygen partial pressure on the structural, microstructural, compositional, optical and electrical properties of NiO films was investigated by X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, spectrophotometer and Hall effect studies. The XRD analysis showed that the preferred orientation changed from (2 0 0) to (2 2 0) as the oxygen partial pressure increases. Fine grains were observed at an oxygen partial pressure of 6 × 10−2 Pa. The deposited films exhibited optical transmittance of 60% and direct band gap of 3.82 eV at 6 × 10−2 Pa. The Hall measurements showed that the electrical resistivity of NiO films decreases as oxygen partial pressure increased to 6 × 10−2 Pa, thereafter increased at higher oxygen partial pressures.