Preparation And Characterization Of Vanadium Dioxide Thermochromic Coating Glass By Radio-Fraquency Magnetron Sputtering

VO₂ undergoes a semiconductor-metal phase transition approximately at 68℃. The transition is accompanied with abrupt changes in its electrical and optical properties,especially in infrared range.So VO₂ films have been proposed as energy efficient window coatings for their thermochromism,with which the solar energy transmission in the IR region may be controlled.In the thesis,VO₂ films were deposited by RF reactive magnetron sputtering with post annealing and without post annealing,and finally VO₂ films with different thickness and good properties of phase transition were prepared at 300℃substrate temperature,which is the unique and creative idea in the experimental research.In the thesis,VO₂ films were deposited on soda-lime glass substrates by rf-reactive magnetron sputtering,the influence of sputtering parameter,especially the oxygen pressure and annealing conditions,on the structure and properties of VO₂ films was studied,the influence of SiO₂ films on the structure and properties of VO₂ films during the heat treatment was also studied.Then VO₂ films with phase transition properties were deposited on 300℃SiO₂ coated soda-lime glass substrates,the electrical and optical properties of the films was studied.The results show as following:1)The sputtering rate decreases gradually with the increase of the oxygen pressure,and the sputtering rate will be a constant when the oxygen pressure increases to 3%.With the increase of the oxygen pressure,the content of V₂O₃ and VO₂ in the films decreases and V₂O₅ increases,as well as thin films' sheet resistance increases. Pure V₂O₅ was deposited with an oxygen pressure of 1.72%.Amorphous VO_x thin films were deposited at room temperature,with no phase transition property.2)Na⁺-ion diffusion is harmful to the crystallinity of VO_x thin films.The SiO₂ interlayer can prevent Na⁺-ion diffusion during the heat treatment.V₂O₅ films were deposited on room temperature SiO₂ coated soda-lime glass substrates,and then were annealed in 450℃reducing atmosphere.The erystallinity of thin films is improved, and with the increase of the time of heat treatment,the valence of V^x+decreases,but there is no VO₂ in the films,the sheet resistance of films decreases at first and then increases. 3)VO₂ films with semiconductor-metal phase transition property were deposited on 300℃SiO₂ coated soda-lime glass substrates.The films have a distortion rutile structure and preferred orientation of(011),and with the increase of sputtering time, the grain size increases and sheet resistance ratio also increases,which is nearly 10³ magnitudes,hysteresis is gradually abrupt and the transition temperature increases. The films have low visible transmittance due to the intrinsic absorption,all the samples exhibit well IR switching properties,and the variation of reflectance increases with the increase of film thickness,and the maximum of which is as high as 59%.