Influence of thermal annealing on optical properties and surface morphology of NiO_x thin films

摘要

NiO_x thin films were deposited by reactive DC-magnetron sputtering from a nickel metal target in Ar+O_2 with the relative O_2 content of 5%. Thermal annealing effects on optical properties and surface morphology of NiO_x films were investigated by X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscope and optical measurement. The results showed that the changes in optical properties and surface morphology depended on the temperature. The surface morphology of the films changed obviously as the annealing temperature increased due to the reaction NiO_x →NiO+O_2 releasing O_2. The surface morphology change was responsible for the variation of the optical properties of the films. The optical contrast between the as-deposited films and 400℃ annealed films was about 52%. In addition, the relationship of the optical energy band gap with the variation of annealing temperature was studied.