Study On Preparation And Composite Modification Of VO₂ Thin Film On Different Substrates

Due to the high sensitivity of vanadium to oxygen,there are many kinds of vanadium oxides in nature.Most vanadium oxides can trigger phase transformation under specific conditions,and various mutations of properties accompany the transformation.Vanadium dioxide（VO₂）has become a research focus because of its phase transition temperature approaching room temperature,picosecond phase transition response time,and excellent metal-insulator phase transition performance,making it of great application value in smart window,laser protection,and photoelectric switch.For different applications,VO₂needs to meet changed conditions.For example,in the field of smart window,it needs to meet the phase transition temperature closer to room temperature,enough visible light transmittance,and solar modulation rate.It needs to have a significant enough near-mid-infrared mutation rate in laser protection.In the field of the photoelectric switch,it requires fast enough phase transition response time and stability.Due to the nature of VO₂material itself,its phase change characteristics can not meet people’s daily needs,and high-quality VO₂film is challenging to prepare,so it has not been widely used in life.Therefore,optimizing the preparation process and modifying VO₂appropriately.Based on VO₂as the research object,the preparation process is optimized,adopting the method of time saving and simple preparation of the high-quality VO₂thin film.A series of characterization methods to characterize the morphology and performance of the VO₂thin film.The introduction of reflector reduction method improved the optical properties of VO₂thin film,making it a step toward the direction of practical application.This paper summarizes the mechanism of metal-insulator phase transformation of VO₂.Its phase transformation characteristics and related applications are included.Several conventional methods of preparing VO₂thin films and associated characterization methods are introduced.By RF magnetron sputtering method,successful in C sapphire and quartz glass surface of two different substrate preparation the preferred orientation of（011）the VO₂thin film with high quality,adopt the way of rapid in-situ annealing to post-processing of film deposition state,and to grope and optimize the process parameters.Compared with the traditional method of preparation of VO₂thin film,our approach saves time and simplifies the procedure.The effect of annealing temperature on the micro-structure and properties of the films was studied.The maximum luminous transmittance of VO₂films introduced on the sapphire substrate was 36.8%.The solar modulating ability up to14.8%,the infrared modulation efficiency（2500nm）can reach to 61.9%,the maximum luminous transmittance of VO₂film submitted on a quartz glass substrate can reach to41.6%.The solar modulating ability of VO₂film submitted on quartz glass substrate can reach to 15.9%.The infrared modulation efficiency（2500nm）is up to 61.9%.VO₂thin films with high quality and phase transformation characteristics and an MgF₂anti-reflective layer on the surface of VO₂thin films were deposited by RF magnetron sputtering method on different substrates.The effects of crystallization quality and thickness of anti-reflective layer on optical properties were investigated.Through the analysis of the experimental results,it is found that the scattering of incident light is more severe for the sample with better crystallinity of the anti-reflective layer,thus reducing the optical properties of the film.The luminous transmittance and the solar modulation efficiency of sunlight can be improved when the reflector thickness is suitable.The optimum reflector thickness of VO₂/MgF₂/sapphire sample is 150nm.The maximum luminous transmittance is increased from 36.8%to 45.9%,the solar modulating ability is up to 10.4%,and the infrared modulation efficiency（2500nm）is up to 54.3%.The optimal anti-reflection layer thickness of VO₂/MgF₂/quartz glass sample is 200nm.The luminous transmittance is increased from 41.6%to 44.5%,the solar modulating ability up to16.7%,and the infrared modulation efficiency（2500nm）is up to 60.9%.Compared with monolayer film,the luminous transmittance and the solar modulation efficiency of composite film are improved.