Preparation Of VO₂ Thin Films And Study On Optical And Electrical Properties

VO₂ material is a widely used on the thermal material, it has a variety of crystal structures, among them VO₂ (M)-and VO₂ (B)-has different features which can be used for different purposes. VO₂ (M) is a kind of functional phase changing material. With the change in temperature, its structure will appear the irreversible semiconductor-metal state transition, at the same time, the mutations of resistance, infrared transmission, and other physical natures will occur, the phase transition point is in the vicinity of 68℃. These properties can be used to switch heat, can also be used in anti-laser radiation. Between 20℃and 100℃, VO₂ (B) has no phase transition, with suitable resistance and high temperature coefficient of the resistance. These advantages for uncooled infrared thermal detection material are very favorable.In my work, RF magnetron sputtered films of VO₂ (M) on general glass, fused silica glass and films of VO₂ (B) on ordinary glass substrate are prepared. By X-ray diffraction (XRD), the VO₂ (M) and VO₂ (B) films were characterized. The ratio of resistance change is tested using Four Probes Method. VO₂ (M) film on the glass substrate resistively changes to two orders of magnitude, on the melting quartz substrate resistively changes to the three orders of magnitude. Resistance - temperature characteristics of VO₂ (B) films were also stadies. With Fourier transform infrared spectrometer and automatic Ellipsometry gage, transmission rate of film - temperature and refractive index - the temperature of VO₂ (M) and VO₂ (B) were study. On ordinary glass substrate VO₂ films changes its transmission rate from 59 percent in the low-temperature state to 23 percent in high-temperatur state, changed by 36 percent; on quartz substrate VO₂ films from the low-temperature state transmission rate of 70 percent to 14 percent of state high-temperature, Changed by 56 percent. On ordinary glass substrate the VO₂ (M) film, the refractive index increased from 2.372 before the phase transition to 2.615 after the phase change; the refractive index of VO₂ (M) film prepared on the quartz substrate, rapid increased from 2.292 to 2.923.