Study Of Microstructural Feature And Properties Of VO₂ Thin Films

Vanadium dioxide is a kind of metallic compound which undergoes a metal-semiconductor phase transition near 68℃. The phase transition is accompanied by significant changes in optical and electrical properties. For the characteristics that its phase transition temperature is near to room temperature and its optical and electrical performance have changed much during phase transition, VO₂ has a great number of potential applications.Many studies have been conducted extensively during the past decades, especially in the films application and preparation process. This material has been taken in use as smart window for controlling solar radiation, protection film for laser shield and infra-red sensitive material in uncooled infra-red focal plane array (UFPA). Some preparation methods, such as organic sol-gel method, pulse laser deposition (PLD) and MOCVD have prepared high capability VO₂ films.The magnetron sputtering method was used in our research for preparation of VO₂ films. Research work has been done as follows in detail:(1) V₂O₅ films was deposited in room temperature substrate, then V₂O₅ films was changed into VO₂ films through heat-treatment. VO₂ films was received by accurate control of the vacuum pressure, heating-treatment temperature, time and gas.(2) How main process parameter of preparation partial pressure of reacting gas (oxygen), substrate temperature and sputtering power influence the properties of the films. And then found the proper experimental condition.(3) Vanadium dioxide(VO₂) thin films were grown onto quartz glass and silicon substrates by two deposition technique. X-ray diffraction, X-ray photoelectron spectroscopy are used to analyze the composition, phase structure, crystalline and valence state of the film. Atomic force spectroscopy is used to identify the film surface morphology. The variation of transmission of films from low temperature to high temperature were also measured. These investigation revealed that films have high purity and good crystallite.(4) Vanadium dioxide(VO₂) thin films by reactive sputtering deposited were endured attacking from infra laser.