Effects of substrate temperature on the resistivity of non-stoichiometric sputtered NiOx films

Thin films of nickel oxide (NiO) were deposited on Corning 7059 glass substrates by RF magnetron sputtering. The relationship between substrate temperature and resistivity and the microstructural defects of the NiO films were investigated. Crystalline NiO film with (111) orientation was obtained in this study. A resistivity of 0.22 Ω cm and a hole concentration of 4.4×1019 cm−3 were obtained for non-doped NiO films prepared at a substrate temperature of 300 °C in pure oxygen sputtering gas. As the substrate temperature was increased from 300 to 400 °C, the resistivity changed from 0.22 to 0.70 Ω cm. The mechanism of electrical conductivity for the NiO films is discussed from the viewpoint of defect chemistry and was confirmed by X-ray photoelectron (XPS) and energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) data.