Annealing effects on VO2 thin films deposited by reactive sputtering

Abstract Two VO 2 film systems (bare VO 2 film on float glass and W-doped VO 2 film with a TiO 2 capping layer) showing optical switching property (semiconductor-to-metal transition) were deposited by radiofrequency reactive sputtering. Their thermal stability was investigated by annealing the films in air at different temperatures. It was found that the VO 2 thin film is quite stable in air below 200 °C. However, after being annealed in air at 300 °C, the pure VO 2 film was oxidized to a V 2 O 5 film. The W-doped VO 2 layer with a TiO 2 capping layer lost its switching property after annealing at 400 °C for 10 min due to inter-diffusion.