Study Of Microscopic Mechanisms And Dynamics Of Vanadium Dioxide

Vanadium dioxide (VO2) thin films will undergo reversible transitions from the monoclinic structure phase of the semiconductor properties to the rutile structure phase of the metal characteristics at about68℃. Accompanied with the phase transition, optical and electrical properties of VO2thin film will occur mutation. Therefore, in recent years, it has been widely applied in the field of uncooled infrared detection and infrared imaging. However, the theory of VO2phase transition has not been well established, and the exploration work is very slow. Through the study of microscopic mechanisms and its dynamics of the vanadium dioxide phase transition, we establish a clear physical picture of vanadium dioxide phase transition microscopic process.In this paper, the high quality VO2thin films were obtained by using a sputtering oxidation coupling method.In the experiments, we found that when the sputtering power is132W, the hysteresis bandwidth of the phase transition is only0.4℃, and in the phase transition, the magnitudes of the resistance change of the film can reach3-4orders. The hysteresis bandwidth occurs regularly changes. First, when sputtering power increases, the bandwidth decreases, and at132W, it has the minimum bandwidth. However, when continuing to increase power, the hysteresis bandwidth is increased again. By analyzing the various factors, it is found that the surface microstructure of thin films affect the hysteresis bandwidth of the phase transition and in theory, the effect is deeply analyzed on the surface microstructuresIn addition, the dynamics of atomic precision VO2phase transition has been explored by using in situ transmission electron microscopy. The Experiments directly observed the microscopic processes of the phase transition. It demonstrates the very important information which cannot provide in other experimental methods. At the same time, we use Raman spectroscopy to study the phase transition process, after researching carefully the peak information Raman spectra at different temperatures, and combining with the results of the theoretical calculations, we analyzed deeply the microscopic mechanism of phase transition.At the end of the thesis, the working principle of the infrared thermal imaging system and the main factors affecting the image quality were analyzed in detail. Then, an uncooled infrared thermal imaging component with low power consumption and a simple structure was designed, using porous silicon as the thermal insulation. Finally, a grief introduction is intended to give on the method of the device fabrication and some key technologies.