Preparation and characterization of nickel oxide thin films by a simple two-step method

As an electrochromic material, nickel oxide thin films have a wide range of applications, such as energy-efficient windows, multi-color display, high contrast and non-radiation information display owing to its high discolor efficiency, good broadband absorption and neutral color properties. This paper presents a two-step method to prepare nickel oxide thin film, which includes the metal nickel films deposited on silicon substrate and followed by thermal annealing. Briefly, metal nickel thin films were deposited by magnetron sputtering below the pressure of 4.5×10^-3 Pa, the voltage of cathode slowly increased from 300V to 600V for about 10 minutes, using argon iron to bombard the nickel target and the sputtering current is 1A. After that, metal after nickel thin films were thermal annealed in the air at 200°C, 400°C and 600°C for an hour, respectively. Scanning electron microscope is used to determine the changes in the surface morphology after the film is annealed at different temperatures. The highest transmittance is obtained for the nickel oxide film annealed at 400°C especially in the wavelength range of 320-720 nm. Results show that crystalline nickel oxide thin film can be formed above the annealing temprature of 200°C.