Effect of RF power on structural, optical and electrical properties of sputtered nickel oxide

In this study, we focus on the effect of the radio frequency (RF) sputtering power on the structural, optical and electrical properties of NiO thin films, deposited on glass substrates in the O2/Ar atmosphere. It was observed that by increasing the RF power from 50 to 300 W, the crystallite size increases from 5.5 to 8.28 nm then decreases for 350 W. The thickness increases from 40 to 800 nm as the power increases from 50 W to 300 W, and decreases to 450 nm for 350 W. Raman spectroscopy analyses confirmed the formation of the NiO phase for all RF powers. SEM images exhibited homogenous and no porous surfaces. Besides, the optical transmittance decreases with increasing the RF power, the band gap is in the range 2.68–3.15 eV and the Urbach energy decreases from 8.06 to 2.04 eV with a minimum obtained for 250 W. The minimum electrical resistivity was obtained for the RF power 50 W.