Thermal, structural and optical properties of NiOx thin films deposited by reactive dc-magnetron sputtering

The NiOx thin films were deposited by reactive dc-magnetron sputtering from a nickel metal target in Ar + O2 with the relative O2 content 5%. The as-deposited NiOx thin films could represent a two-component system comprising crystalline NiO particles dispersed in an amorphous Ni2O3. Decomposition temperature of the as-deposited NiOx thin films was at about 263 °C. After annealed at 400 °C for 30 min in air, the surface morphology of the films became very rough due to the decomposition of the Ni2O3, leading to the changes of the optical properties of the NiOx thin films. The reflectivity of the films annealed at 400 °C was lower than that of the as-deposited one and the optical contrast was 52% at 405 nm.