Research On Preparation Process And Phase Transition Characteristic Of Vanadium Oxide Thin Films

In the1860s, the scientists Morin found the characteristic of phase transition ofvanadium oxide in bell LABS. Then more and more people begin to pay closeattention to and research vanadium oxide, the electrical and optical properties ofvanadium oxide film have violent changes before and after the phase transition, thismake vanadium oxide film widely used in intelligent window, micro bolometer, phasechange memory and optical switch, etc.The preparation technology is of great influence for the properties of vanadiumoxide film, the appropriate preparation technology can not only improve theperformance of the film, but also reduce the costs and increase the efficiency. And thereaction sputtering and heat treatment is one of the film preparation methods whichwere most widely used, the film made by this method was of high purity andcompactness and good combined with substrate, but it need more control parameters,in which the percentage of argon and oxygen directly affect the performance of thefilm, so the preparation technology is more complex. This paper studies a kind of newmethod of preparation technology, first, preparating the vanadium metal film was bythe sputtering direct thchnology, and then the film was treated in pure oxygenenvironment of rapid thermal process, and in order to improve the characteristic ofphase transition, the film was treated in pure nitrogen environment of rapid thermalprocess, each thermal process used only a single gas, preparation technology wasrelatively simple. The Four-point probe method,THz time domain spectrumtechnology,AFM,XRD and XPS were imployed to analyze the influence of thermalprocess parameter for the the characteristic of film phase transition.The experimental results show that higher valence state of vanadium oxide andbigger surface particle was appeared along the longger of heat treatment temperatureor heat treatment time. Among them, after450℃/40s rapid thermal process in pureoxygen environment the metal V thin film was becomed VOXthin film which had lowproperties of phase transition.Before and after heating the change of resistivityreached2dec-ades and the range of the THz transmission intensity showed smoothchange.In order to improve the properties of phase transition,the VOXthin film was treated by500℃/15s rapid thermal process in pure nitrogen environment.Afterthat,we found that the thin film shows a good phase transition performance,accompanied by a sheet square resistance drop of above3dec-ades and a56.33%reduction in THz transmission intensity.In order to further analysis the influence of substrate for the characteristics ofvanadium oxide thin film phase transition, we choose three different substrate of Si,SiO2and Si3N4to prepatate vanadium oxide thin film in the same process parameter,the test data are analyzed, and the results show that substrate have great influence forthe characteristic of vanadium oxide film phase transition, the substrate of oxidesubstrate such as SiO2substrate, in the thermal process of high temperature, canrelease oxygen along enhancement of surface icon activity, making the vanadiumatom oxidation enhanced. For non oxide substrate such as Si3N4substrate, substratesurface ion activity enhancement can absorb oxygen atoms in the thermal process,making the vanadium atom oxidation abated.