Study On The Preparation Of VO₂ Film By High Power Impulse Magnetron Sputtering And Its Infrared Radiation Property

The VO₂ film has dynamic spectral control characteristics in the solar radiation band and the mid and far-infrared band,which is very suitable as a photothermal control device.However,due to the harsh preparation conditions of the VO₂ film,a higher preparation temperature is required,which limits the photothermal control designed the selection of device material system based on the VO₂ film,so reducing the preparation temperature of VO₂ film is of great significance for its practical application.In this paper,high power impulse magnetron sputtering?Hi PIMS?technology is used to prepare VO₂ thin films at lower temperatures,and the infrared radiation characteristics of different substrates are studied.The main research contents are as follows:First,the high power impulse magnetron sputtering technology was used to prepare the VO₂ film,and the relationship between oxygen-argon ratio,pulse frequency,sputtering power and preparation temperature was explored.In the preparation process,by controlling the ratio of oxygen and argon,it was found that the peak current in the pulse cycle increased with the increase of the oxygen-argon ratio,and the increase of the oxygen-argon ratio was conducive to the decrease of the VO₂ film preparation temperature.The effects of different pulse frequencies on the discharge characteristics are studied.The results show that the peak current increases with the decrease of the pulse frequency,and it is conducive to the decrease of the VO₂ film preparation temperature.Control the average power of high-energy pulsed magnetron sputtering and study the influence of the average power change at different temperatures on the crystal phase,element valence state and surface morphology of VO₂ thin film.By adjusting the average sputtering power to achieve preparation at 350 ? with excellent heat VO₂ film with color-changing properties.Comparing the VO₂ films obtained at different temperatures,it was found that the lower the preparation temperature,the poorer the crystallinity of the obtained film.The surface of the VO₂ film was composed of isolated particles to form a dense film without cracks and other obvious defects.As the preparation temperature decreases,the thermochromic ability of the obtained VO₂ film decreases,but the phase transition temperature is less than 68 ?.In addition,at 400?,VO₂ thin film was prepared on the surface of ITO glass by high-energy pulse magnetron sputtering technology,and it was found to have obvious thermally induced phase transition characteristics through temperature-variable transmission spectrum test.Then,the infrared radiation characteristics of a single VO₂ thin film,VO₂/Si O₂ and VO₂/Al composite structure were simulated by finite difference time domain method?FDTD?,mainly to explore the intrinsic action mechanism of substrates with different infrared radiation characteristics on the infrared spectrum performance of VO₂ film before and after phase transformation.And the influence of the thickness of VO₂ film on the change value of infrared emissivity of the photothermal control device is studied emphatically.The simulation results show that the single VO₂ film exhibits high transmission/low reflection spectral characteristics before the phase transition in the 2.5?25 ?m band,and shows low transmission/high reflection spectral characteristics after the phase transition.The transmittance before and after the phase transition in the 2.5?25?m band gradually decreases,and the reflectivity gradually increases.The changes in reflectivity and transmittance first become larger as the thickness increases,and then tend to stabilize.Based on the intrinsic spectral characteristics of the VO₂ thin film,the substrate materials Si O₂?high emission characteristics?and polished Al flakes?high reflection characteristics?with different infrared radiation characteristics were selected to study the infrared radiation control characteristics before and after the phase transition.Due to the high emission characteristics of Si O₂,the VO₂/Si O₂ composite structure exhibits the characteristics of infrared radiation with low emission at high temperature and high emission at low temperature in the entire waveband of 2.5?25 ?m.However,due to the high reflection characteristics of Al,the VO₂/Al composite structure presents the characteristics of infrared radiation with low emission at low temperature and high emission at high temperature in the entire waveband of 2.5?25 ?m.And the change value of infrared emissivity of the above two composite structures increases first and then decreases as the thickness increases.And when the thickness of VO₂ film is 0.3 ?m,the change value of emissivity ?? reaches the maximum.Finally,by depositing VO₂ thin films on quartz glass and single polished Al wafers,the infrared radiation characteristics at different temperatures were studied by infrared thermal imaging cameras,and the changes in infrared radiation characteristics before and after the phase transition of the VO₂ film on different substrates were verified experimentally.