NiO thin films obtained by RF magnetron sputtering with ion-beam treatment: structural, electrical, optical and nonlinear optical properties

Nickel oxide NiO thin films have been synthesized by RF magnetron sputtering with accompanying ion-beam treatment. The films were synthesized on glass substrates at three different partial pressures (4, 6 and 7 %) of oxygen in the working chamber. Depending on the current density of the ion beam used for the treatment and the oxygen pressure, the thickness of the films ranged from 100 to 800 nm. A significant influence of the ion beam current density on the parameter <D> characterizing the average crystallite size of NiO, as well as on the parameters of its crystal lattice, was shown by X-ray diffractometry. An absorption band near the wavelength of 232 nm was detected in the optical reflectance spectra of the films measured in the range of 190-1100 nm. Using z-scanning method with a nanosecond laser at a wavelength of 532 nm it is shown that the synthesized films exhibit nonlinear absorption due to two-photon absorption. It is demonstrated that there is an optimal current density of ion-beam irradiation at which the nonlinear absorption coefficient of the films reaches the maximum value and their resistivity reaches the minimum value.