Thermally Induced Color Vanadium Oxide Film Preparation, Structure And Performance

Vanadium oxides have very complicated phase structures. At least 8 vanadium oxides experience low-temperature semiconductor to high-temperature metallic transition at a range of -147℃～68℃. In particular, VO2 is the most studied materials among those because of its transition temperature (68℃) close to room temperature. It exhibits abrupt change in its electrical and optical properties, thus they are used in many technological applications, such as in smart window, optical storage, laser protection and infrared detector and so on.At present vanadium oxide films are mainly produced by reactive magnetron sputtering. Many factors affect the reactive magnetron sputtering processes and there are many types of vanadium oxide, still the window range for preparing VO2 with a reversible phase transition at 68℃are narrow, consequently, it is very hard to get phase-singled VO2 thin film. Accordingly, it is primary to find technological conditions of preparing phase-singled VO2 for fabricating thin film functional applications. This theme focuses on the influence of sputtering power, sputtering pressure and deposition temperature on the phases and properties of prepared vanadium oxide thin films.As a result, phase-singled VO2 thin films are got under the sputtering power of 200watt and 250watt accompanied by the substrate temperature of 350℃and 400℃each other. However, due to various preparation conditions, we got various types of VO2. The growth of thin films has distinct prefer-orientation under the condition of heating substrate. In addition, the increased substrate temperature is benefit for crystallization and its crystalline grain growth is cylindrical. Since sputtering processes are complicated, there are inhomogeneous of micro-domains in the thin films.Based on the former experiments, we preliminary investigate the influence of W-doped in the thin film on its phase and properties by dual-sputtering. The research indicates that the doped tungsten has little effect on the phase of thin film when the sputtering power is at 150watt, still as V2O5, but as the power increasing to 200watt, the phase has been changed from +4 valance to low-valance vanadium(V2O3). Doping is conducive to the formation of low-valance vanadium V2O3.