Preparation of pure NiO thin film by radio frequency magnetron sputtering technique and investigation on its properties

The use of nickel oxide as a complementary electrode in electrochromic devices is found to be widespread because of its high coloration efficiency and low materials cost. In the present work, we investigate the properties exhibited by radio frequency (RF) magnetron sputtered nickel oxide (NiO) thin films. The optical, vibrational and morphological characteristics of prepared nickel oxide thin films are tuned with different RF powers (100 W, 150 W and 200 W). The deposited nickel oxide films’ photoluminescence spectra reveal broad band-edges, Ultra-violet emission at 365 nm accompanied by defect-related, at 420 nm (DLE1) and 485 nm (DLE2) which occurred due to deep-level-emission (DLE). The Raman peaks centred at 560 cm−1 are related to 1-phonon longitudinal optic (LO) mode. The peak observed at 1100 cm−1 corresponds to the 2-phonon LO mode of nickel oxide, which is due to the defects of nickel vacancy or an increase in Ni3+ ions. Field emission scanning electron microscopy characterization reveals the prepared films are uniform and pinhole free nature, resulting in a high quality film. The EDX spectrum confirms the purity of the nickel thin film obtained.