Doped Vanadium Oxide Films And Resistance Mutations In The Characteristics Of Study

VO₂ is a typical thermochromic material. With the increase of temperature, the semiconductor-to-metal transition will occur at 68°C; with the abrupt change of VO₂ crystal structure, electrical resistance and optical index of refraction transmissivity and reflectivity will change, which results in great application potentials in many fields. Since 1980s research about doped VO₂ matrix has shown that doping could alter the phase transition temperature of VO₂ thin film, and as a result, influence on its optical and electrical properties. Due to the requirement of VO₂ phase transition temperature near to room temperature in practical application, whether phase transition temperature of VO₂ could be decreased to the room temperature by doping has become the hot topic relevant to VO₂ film property modification in recent years.According to the development trend and practical need of VO₂ thin film, in this study, some basic research in the field of VO₂ film property modification by doping with transitional metals at various valences such as Zr⁴⁺ and Cr³⁺ has been focused on. Specifically, the architecture of this dissertation is as below:At first, using inorganic sol-gel method VO₂ thin films doped by Zr⁴⁺ ion were prepared. By varying the doping concentration of Zr⁴⁺, corresponding resistance-temperature curves were measured. On the other hand, relationship between doping concentration, phase transition temperature, magnitude of resistance change and hysteresis width was investigated. Results show that the increase of semiconductor-metal phase transition temperature and the decrease extent of resistance is linear to Zr⁴⁺ doping content, while the hysteresis width of VO₂ thin film fluctuates with Zr⁴⁺ doping content.Then, the effect of vacuum annealing temperature on VO₂ thin film phase transition temperature, magnitude of resistance change and hysteresis width by doping Zr⁴⁺ was discussed. Compared with testing results at different annealing temperatures ranging from 350 to 500°C, it was found that VO₂ film annealed at 450°C exhibits lower phase transition temperature and significant resistance change. Therefore, the optimum annealing temperature for VO₂ film of 450°C was achieved.