Structural, surface and optical investigations of Cu+ implanted NiO film prepared by reactive sputtering

Nickel oxide (NiO) films were deposited on silicon substrate using a DC magnetron sputtering system. The deposited films were annealed at 400 o C for two hours and then irradiated by 500 keV copper ions (Cu + ) in the dose range of 1 × 10 11 to 1 × 10 14 ions-cm −2 using Pelletron Accelerator. X-ray diffraction study revealed NiO and Ni phases in the films corresponding to (111) and (200) planes. The lattice parameter was increased with the increase of ion dose to 1 × 10 12 ions-cm −2 and then decreased at the higher doses. Ion irradiation at 1 × 10 11 ions-cm −2 improved the crystallinity of the film while at the higher doses, the crystallinity was decreased. The surface morphology of the films showed a decrease in the compactness of the granular structure with increasing the ion dose. Fourier Transform Infrared spectroscopy showed Cu–O and Ni–O stretching vibration peaks in the irradiated films. X-ray photoelectron spectroscopy (XPS) results revealed a decrease in N i O and increase in the N i + 3 N i + 2 ratio with an increase of the ion dose to 1 × 10 12 ions-cm −2 , demonstrating an increase in the Ni vacancies in the film at lower doses. The depth-resolved XPS analysis displayed a change in the Ni and O atomic percentages in the film with the increase of the etching time from 50 to 250 sec and validated the existence of metallic Ni in the NiO film. The photoluminescence (PL) spectra analysis showed a decreasing trend in the band gap of the NiO film irradiated up to 1 × 10 12 ions-cm −2 , then an increasing trend at the higher doses.