Preparations And Properties Of VO_x Thin Films For Uncooled Infrared Detector

VO_x thin films is a infrared thermo-sensitive semiconductor material.As a special function material,vanadium dioxide(VO₂) has attracted great interest and been extensively studied.VO₂ undergoes a semiconductor-metal phase transition approximately at 68℃which is near room-temperature.The transition is accompanied with an abrupt change in its electrical,magnetic susceptibility,thermal capacitance and optical properties.It can be widely used in uncooled infrared detector,thermalchomic switches,photoelectric switches, optical storage and so on.In chapter 1,the crystalline structure,properties,all kinds of preparing methods and the potential applications about VO_x thin films are introduced.In chapter 2,we systematically introduce the theory and process of radio frequency(RF) magnetron sputtering and ion beam deposition sputtering(IBD).The preparations of VO_x thin film are introduced in detail.Finally,we summarize the characterization techniques used in our experiments.In chapter 3,we study the RF magnetron sputtering process of VO_x thin films,at the same time the influences of O₂/Ar flow ratio,working pressure,substrate,sputtering time and anneal temperature on the electrical resistance mutation are induced.The scanning electron microscope(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy (XPS) of O₂/Ar flow ratios and different substrates are studied in VO_x films.The results show that the VO_x thin film with the CVAr ratio of 0.5:50,the sputtering power of 120W, the working pressure of 1.5Pa has a good quality crystalline structure.The thin flim is annealed in vaccum.The more is content of VO₂ phase and larger an abrupt resistance change is.The thin flims on Si substrates are better than the flims on glasses.In chapter 4,we study the DC and RF magnetron sputtering process of VO_x/TiO_x thin films and VO_x/TiO_x/Ti multilayer thin flims.The results show that the buffer of titanium oxide or titanium thin films,are benefit to the crystalline quality of vanadium oxide thin films.The stress between the glass substrate and the vanadium oxide thin films is reduced.In chapter 5,we study the internal friction of VO_x/TiO_x/Ti multilayer thin flims on molybdenum substrates with DC and RF magnetron sputtering process.A phase transition of multilayer thin films occurs at 66℃,which is revealed to the mutation in crystal structure,resistance and Young' s modulus.This is confirmed by mechanical properties and electrical properties.