Research On Fabrication Of Titania Thin Films And Nanostructures By Magnetron Sputtering

B1 In this dissertation TiO₂ thin films and its novel nanostructures have been prepared by magnetron sputtering and the effects of process parameters on the growth and structure of the TiO₂ films and nanostructures were investigated. The preparation of the TiO₂ thin films were carried out by reactive sputtering, where the effects of gas flow rate ratio of O₂/Ar, working pressure, substrate temperature and sputtering power on the film growth were investigated systematically. By oxidizing metal films deposited by magnetron sputtering at different conditions the TiO₂ nanostructures were prepared, where the roles of metal film composition, oxidizing temperature, heating rate, heating duration played on the formation of the nanostructures were investigated.In this study Raman spectroscopy, XRD, SEM and Ellipsometry were used to characterize the products. It is indicated that the gas flow rate ratio of O₂/Ar, working pressure, substrate temperature, and sputtering power influence the crystal structure, crystallinity and deposition rate greatly. Especially, the O₂/Ar flow rate ratio influences the deposition rate and structure notably. The deposition rate can be effectively increased by optimizing the working pressure. The anatase structure was mainly obtained below 500 oC while the rutile structure was only obtained at elevated temperature. Higher sputtering power redounds to increasing the crystallinity and deposition rate. The optimum deposition conditions are that of O₂/Ar ratio 1:6, sputtering pressure 1.5 Pa, substrate temperature 500 oC and sputtering power 400 W.The TiO₂ films prepared by magnetron sputtering are usually composed of small particles, exhibiting a uniform flat morphology, rather than nanostructures with unique properties. However, the novel nanostratures play a significant role on the application of sole cells and photocatalysis. In this work, the nanostructural TiO₂ films were obtained by oxidizing the sputtering deposited Ti films. It indicated that the heating temperature and metal film composition greatly influence the growth of nanostructure. With increasing the temperature from 400 oC to 600 oC, the morphology of the nanostructures evolves from nanorod to nanosheet. Cu and Zn with lower melting temperature were introduced into the Ti films for inducing the growth of TiO₂ nanostructures. In this case, nanoneedles and nanosheets were grown on a large scale by directly oxidizing Cu-Ti and Zn-Ti composite metal films. Interestingly, a grid micropattern was observed in the growth of nanoneedles, which obtained by directly oxidizing Cu-Ti multilayer films with a certain atomic ratio of Ti and Cu at 500 oC.