Study On The Microstructure And Characteristic And Its Growth Model Of TiO₂ Thin Films

As a class of material with special appearance, thin film has particular optical, mechanical, electroniccal and magnetical properties, and was used as the basic material in many new application fields, such as microelectronics, optoelectronics, magnetoelectrics, overhardening of cutting tools, sensors and the application of solar energy, etc. As a prospective dielectric material, TiO₂ thin film was used in thin film technique, which brings a great interest to the researchers of all over the world. Firstly, as an important optical thin film, it has the many good properties of high transparence in visible region, high refractive index, high chemical stability, high strength and high degree of hardness, which applied widely to anti-reflection coatings, interference filters, electrochromism windows and thin film optical waveguides. Second, as an electronic thin film, TiO₂ thin film has good insulatibity to be used as protection layers of large-scale integrated circuit (LSI), and TiO2 thin film also has high dielectric constant, which can be applied to gate dielectric of semiconductor device, MEMs and MOS. Thirdly, TiO₂ thin film has the good properties of sensitiveness on gas, which can make thin film sensor to test the tail gas of car, the oxygen content in the air and the leakage hydrogen. Also, TiO₂ thin film has good properties of photochemical catalysis, which can be applied to the fields of surface self-cleaning, water treatment, sterilization and anticancer.With the development of thin film science and technology, various thin film preparation techniques developed rapidly, as a result, conventional so-called filming has developed from single vacuum evaporation to many new film preparation techniques, such as ion plating, sputtering, laser deposition, CVD, PECVD, MOCVD, MBE, liquid growth, microwave and MTWECR, etc., of which vacuum evaporation is the common technology for thin film preparation, because it has the distinct advantage of high quality of film deposition, good control- ability of deposition rate and high versatility. The chemical composition, micro- structure and optical properties and its application of TiO2 thin films deposited on K9 glass by using reactive electron-beam evaporation (REB) are studied through SEM, TEM, XPS, XRD, spectroscopic ellipsometry (SE) and UV-Vis spectrophotometer in the dissertation, and the progresses of nucleation and growth of thin film are discussed from the point of view of dynamics and thermodynamics so that a structure model of TiO₂ thin film is brought forward.The best process for high quality TiO₂ thin film deposited on K9 glass by REB is studied by using orthogonal test method, the SE results indicate that the best process for TiO₂ thin film deposition is the substrate temperature of 300℃, the total gas press in the chamber of 2 X 10²Pa and the deposition rate of 0.2 nm-s-1, of which the substrate temperature has influence on the optical properties of the deposited films notably. And the results have good repeatability,,Influence and its mechanism of substrate temperatures (from 120℃ to 300℃) and heat treatment temperature (400℃, Ih) on the chemical composition, micro- structure and optical properties of TiO₂ thin film deposited at the condition of pressure in depositing chamber being 2 X 10-2Pa and deposite rate being O.Znm-s-1 are studied through modern analysis technologies. The results indicate that (a) before heat treatment, with the increasing of substrate temperatures, content of lower valency (TiJ+) decreases, the stoichiometric proportion of O/Ti in all samples is about 2; the films have amorphous incompact columnar fiber structure, and with the increasing of substrate temperature,the size of columnar fiber increases; the films have good hyalescence in visible range and great absorbability at the wavelength of 350nm; optical constants of the films are calculated from the transmittance spectrums in visible range by mathematical analysis of the orders of interference, the results show that the refractive ind...