Fabrication and Characterization of Nanocrystalline VO_2 Thin Films

Nanocrystalline VO₂ films with phase transition temperature 34°C have been fabricated on Si₃N₄-film-coated silicon and quartz substrates by argon-annealing films of metastable VO₂(B). The original VO₂(B) films are obtained by ion beam sputtering in an argon-oxygen atmosphere at 200°C. The nanocrystalline VO₂ films exhibit strong changes in electrical and optical properties when a phase transition is completed. The phase transition temperature in the as-fabricated samples is about 34°C, which is smaller in comparison with 68°C in the single-crystalline VO₂ material. A lower phase transition temperature is favorable for device applications such as smart window coating and low power consumption optical switching.