Synthesis of NiO [111] Thin Films on c-Al2O3 Substrates by Pulsed Laser Deposition

Thin NiO films with thickness from 40 to 170 nm were obtained by pulsed laser deposition on c‑Al2O3 substrates using the second harmonic of YAG:Nd3+ laser for ablation of a metal Ni target in a vacuum chamber at an oxygen pressure of 7.5 mTorr and a substrate temperature of 370°C. Using X-ray diffraction, all NiO films were shown to have high crystalline perfection and the [111] orientation. The surface roughness of the obtained films was in the range from 1.6 to 2.3 nm. It was found that with increase in NiO film thickness the charge carrier concentration decreases and the specific resistance increases. According to measurements of the optical properties of the films, the band gap increases from 3.43 to 3.63 eV with decreasing thickness.