Annealing effects on VO2 thin films deposited by reactive sputtering

Two VO2 film systems (bare VO2 film on float glass and W-doped VO2 film with a TiO2 capping layer) showing optical switching property (semiconductor-to-metal transition) were deposited by radiofirequency reactive sputtering. Their thermal stability was investigated by annealing the films in air at different temperatures. It was found that the VO2 thin film is quite stable in air below 200 degrees C. However, after being annealed in air at 300 degrees C, the pure VO2 film was oxidized to a V2O5 film. The W-doped VO2 layer with a TiO2 capping layer lost its switching property after annealing at 400 degrees C for 10 min due to inter-diffusion. (c) 2006 Elsevier B.V. All rights reserved.