Influence of InN epilayers on structural, electrical and optical properties of NiO films grown by magnetron sputtering

•The NiO films were prepared on GaN substrate by magnetron sputtering.•The InN epilayer is critical to influence the physical properties of NiO films.•The vacuum annealing could improve the crystalline qualities of NiO films.

The NiO films were prepared on GaN substrate by depositing an InN epilayer on GaN by plasma-assisted molecular beam epitaxy (PAMBE) and then growing NiO films on InN epilayer by radio frequency (rf) magnetron sputtering. We studied the effect of InN epilayers on structure, surface morphology, electrical and optical properties of NiO films using X-ray diffraction (XRD), scanning electron microscopy (SEM), Hall and optical absorption measurement. It was found that the NiO films grown with InN epilayer exhibited better crystalline qualities with more coalescent surface morphologies and an enhancement of the electrical properties. Moreover, the effect of vacuum annealing on the crystalline qualities of the NiO films was also investigated.