Low phase transition temperature VO 2 Films
|School||Huazhong University of Science and Technology|
|Keywords||VO2 thin films Phase transition Temperature coefficient of resistance Micro- bolometer Reactive ion beam sputtering|
Since VO 2 occurs at 68 ℃ for metal - semiconductor phase transition is known, in the event of a metal - semiconductor phase transition process, VO 2 Crystal structure will also change from low temperature monoclinic structure into a high temperature tetragonal rutile structure. While the phase change can also cause VO 2 thin film optical and electrical properties of mutations at low temperatures (lt; 20 ℃), VO 2 Films on the infrared light to maintain a high permeability over rate, while at high temperatures (gt; 50 ℃), VO 2 film also by the low temperatures of the high permeability of the infrared light into high contrast, and the semiconductor state to a metallic state transition process, VO 2 thin film resistor will reduce the three to four orders of magnitude. Because of these two excellent features, VO 2 film very broad range of applications, mainly used in micro-bolometer, solar smart windows, laser protection, optical switches and optical storage and so on. At present, a lot of research work revolves around reducing VO 2 Films phase transition temperature and improve its visible light transmittance two aspects. The main contents are as follows: 1. Analyzes VO 2 phase change mechanism of the film, using TFCalc coating design software for the glass as the base film are designed to give the optimum transmittance Film thickness of each layer theory, as a guide for subsequent experiments; 2 introduces the reactive ion beam sputtering and magnetron sputtering VO 2 thin film process, and using reactive ion beam After the annealing step sputtering method to obtain a good performance of the phase transition VO 2 films on vanadium dioxide thin film growth and phase transition properties of a very significant number of process parameters, namely the substrate temperature, annealing temperature, annealing time and oxygen argon flow in depth analysis and discussion, and ultimately get the best process parameters; 3 with a four-probe tester, infrared spectroscopy, X-ray diffraction instrument (XRD), scanning lens (SEM) and atomic force microscopy (AFM) of the electrical properties of the film, optical characteristics, surface morphology and phase composition were tested. The results showed that the resulting VO 2 Films nanometer particle size, and the phase transition temperature is 30 ℃, low temperature to high temperature infrared light transmittance tests showed the film has good infrared light switch characteristics; 4 introduces VO 2 film solar smart windows and micro-bolometer aspects of the application.