Preparation And Optical Properties Of Metal-doped TiO₂Films By Magnetron Sputtering

Titania （TiO₂） has a wide application in optics, optoelectronics and electronics, and many other scientific fields because of its stable chemical property, clear optical characteristics, low price and other notable features, so it cause more and more people’s attention. However, TiO-2is a wide band gap （E_g=3.0eV-3.2eV） indirect band gap semiconductor material. There are two major shortcomings exist in the application process: First, TiO₂can only absorb ultraviolet light, the wavelength must be less than385nm, and the utilization of visible light is only5%; Second, the photo-generated electron-hole pairs’ recombination probability of TiO₂is very high, quantum yield is low （about4%）, this results in low efficiency photovoltaic. These factors affect the application of TiO₂in practice. When the metal ions into the titania crystal lattice defect levels will be formed between the TiO₂energy levels, so the energy band structure of TiO₂will be changed. Since the doped metal oxide has a smaller energy gap, therefore, it can absorb a wide wavelength range of photons, which makes the modified TiO₂intrinsic absorption edge red shift; thereby the absorption spectrum of TiO₂has been expanded. At the same time the metal ions can accept the excited electron from TiO₂valence band, making it become capture shallow potential well of photo-generated electron-hole pairs, thus electron-hole pair recombination rate is reduced.This thesis prepared different metal-doped （Zn, Cu） TiO₂thin films at different preparation conditions by RF magnetron co-sputtering way. Studying of the effects of preparation conditions on the structural characteristics by X-ray diffraction （XRD）, atomic force microscopy （AFM）, profile gauge, scanning electron microscope （SEM）, Energy Dispersive Spectrometer （EDS）,UV-visible spectrophotometer （UV-Vis）. And the structure influence on optical properties was investigated. Through the introduction of metal ions to adjust the energy band structure of TiO₂film, increase its effective absorption of visible light, as well as enhance its ability to capture electronic, help to separate photo-generated electron-hole pairs effectively. Ultimate achieved its optical band gap is adjustable.