The Ion Beam Doped Optical Properties Of Nanometer Thin Films Of Titanium Dioxide

TiO2 is a kind of semi-conductor with excellent performances. It has many advantages such as high photo-catalytic activity, stable chemical properties, nontoxicity, low cost, and so on, which makes TiO2 widely applied in environmental engineering, biological medical physics, material science and daily living as the material of environmental prospection and photocatalysis. In this work, TiO2 films have been successfully deposited on the slide glass by a R.F. reactive magnetron sputtering system. Moreover, a method of doping N ions into the films by ion implantation has been presented. At the same time, the optical properties of the N-doped TiO2 films have been studied and the effects of the substrate temperature, oxygen partial pressure, annealing temperature and the hydrothermal temperature on the properties of the TiO2 thin films have been investigated. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM), UV-visible spectrophotometer and SRIM 2006 calculation code were utilized to characterize the optical and structural properties of the films.Such contents involved in this dissertation are as following:1. Homogeneous transparent TiO2 films had been successfully deposited on the slide glass a by R.F. reactive magnetron sputtering system. The grains on the surface of films are uniform and compact, and the average transmittance of all samples is above 80%. After N doping, transmittance of each group of films decreased. However, the absorbance of the films increased, and the absorption edge shifted as well.2. The substrate temperature during the sputtering process has great influence on the crystal structure and optical properties of TiO2 films. When the substrate temperature was 20℃, the crystal structure of films was anatase. As the substrate temperature reached 300℃, the crystal structure of anatase is still the main structure of the films. After N doping, the transmittance of this group of films decreased. However, the absorbance of the films increased, and the absorption edge shifted to the longer wavelength as well with the increasing fluence of N ions.3. The oxygen partial pressure during the sputtering process has great influence on the crystal structure, surface morphology and optical properties of TiO2 films. During the oxygen partial pressure gradually increases, the stability of the anatase increased. After N doping, the absorbance of the films increased in the UV-Vis range, and the absorption edge shifted to the longer wavelength as well with the increasing fluence of N ions.4. The crystal structure of TiO2 thin films were anatase after annealing at different temperatures. The grains on the TiO2 films surface recrystallized with the increase of the annealing temperature. When the annealing temperature reached 500℃, the degree of TiO2 films recrystallization improved.5. The temperature of hydrothermal treatments had great influence on the preferential growth of grains on TiO2 thin films. The preferential oriented nano-pole grains appeared at 150℃after hydrothermal treatment for 4h.