Modification of the optical and electrical properties of NiO films by thermal annealing

Physical materials technology

This paper presents the results of studying the effect of thermal annealing on the optical and electrical characteristics of NiO films. NiO layers were synthesized using DC magnetron sputtering from a Ni target. The films were deposited in an Ar/O2 gas mixture with a ratio of 70%/30%, respectively. The deposition power was 100 W. The resulting films had low transparency and high conductivity, which is associated with a high content of oxygen vacancies
in the NiO structural layer. The influence of thermal annealing on the characteristics of NiO films was studied on films obtained by magnetron sputtering. Annealing was carried out in an oxygen-containing environment at temperatures from 200 °C to 550 °C and an annealing duration from 5 to 120 minutes. The results of optical studies have shown that annealing at temperatures up to 550 °C leads to an increase in transparency from 5% to 80% at a wavelength
of 700 nm. In this case, an increase in the temperature and duration of the process is accompanied by an increase in the optical band gap. A similar trend was observed in the study of film conductivity, where an increase in the  annealing temperature leads to an increase in resistivity from 0.2 Ω cm to 1460 Ω cm.