Investigation Of Fe-doped VO₂ Film Prepared By Polymer-assisted Deposition

Temperature change in a certain range could induce first-order phase transitionin vanadium dioxide. For example, pure VO₂ single crystal undergoes a metal-insulatortransition（MIT） with an abrupt resistivity change of 4-5 orders of magnitude as thetemperature is 68 ℃. The pronounced changes occurs not only in the electrical, but alsoin the optical and magnetic properties. Hence, such unique characteristic should beconveniently utilized in many applications, but comparing with bulk of VO₂, the film ofVO₂ has more extensive application, such as thermal sensor, light-activated switch andsmart window coating materials, etc. But different phase-transition temperature isdemanded for VO₂ used in various application scenarios. 68 ℃ will be an enormouslimitation in the applications. As we all known that different substrates, depositing indiverse thickness and doping could affect The phase transition properties. Among theseways, doping is the most convenient method. In recent years, many researchers havetried to dope varieties of impurities to investigate the influence on the properties of VO₂.There are some literature reporting that doping by W,Ti and Mg and so on could impactthe transition temperature, the infrared transmittance and the blue-shift in the absorptionedge, respectively. However, there is few report about Fe-doped VO₂. So this articledevoted to investigate the change in the properties of VO₂ after Fe doped, and itdemonstrated that Fe doping could reduce the phase transition temperature while thereis no greatly effect on variation of resistance in practice and theory, what`s more, it canshrink the intermediate phase and narrow the wide of hysteresis, thus makes the film ofVO₂ more sensitive to the variations in temperature, and make the abrupt change inresistance more quickly, it created good conditions to make the heat-activated switchwith better applications.The main dissertation of this article aims to prepare VO₂ films by polymer assisteddeposition, and investigate the change in structure and phase transition properties afterdifferent contents of Fe doping. The main research contents are as follows:1. Prepare excellent VO₂ films on sapphire substrate by Polymer assisted deposition,and achieve the optimal condition by controlling the manufacture process such asgas atmosphere and annealing temperature.2. Prepare Fe-doped VO₂ films by the optimal process of polymer assisted deposition,and do the measurement of XRD\XPS\AFM for different Fe contents samples andresearch the effect on the crystal structure, morphology, and chemical valence stateofvo2filmbydifferentfecontentsdoping..3.testingtheresistanceoffe-dopedvo2filmsindifferenttemperaturebyusingvanderpauwmethod.wegottheeffectofdopingcontentoffeonthepropertiesparametersuchasphase-transformtemperatureandthewideofhysteresiscurvebyanalyzingther-tcurve.then,weinvestigatedthatifthesecondphaseofvo2filmsoccurandprovetheconclusionbyramantestingintheend.