Nano Tio <sub> 2 </ Sub> Thin-film Structure And Optoelectronic Properties Study

Nanocrystalline film has special optical, mechanical and electromagnetic properties differing from common material because of its quantum size effect, minor sized effect, skin effect and macroscopical quantum tunnel effect et al. Nanocrystalline titanium oxide film has many characters such as high transmittance, high refraction index, good chemical stability, high intensity and rigidity, so it is widely applied to antireflection coating, interference filter, electrochromic windows, film optical waveguide, solar battery and photoelectric conversion et al. Acted as photocatalysis film, titanium oxide is widely applied to sterilization, anticancer, water and air disposal et al.In this paper, nano-TiO2 thin film is successfully prepared with electron beam evaporation. After analyzing the influence of all kinds of technologic conditions to refractive index of TiO2 film, optimal technologic conditions is that substrate is 200 ℃, the chambervacuum is 2× 10-2 Pa, the deposition rates is 0.2nm/s. Then annealed and doped TiO2 film is researched. Annealing and doping influence its morphology, phase, and properties, such as refractive index, transmittance and absorption of light et al. The results indicate that doping CeO2 make band gap value reduce from 3.27ev to 2.5ev, resulting in the absorption edge shifting from 380nm to 495nm.In this way, more solar energy is utilized. XRD results show that doped- CeO2 inhibits the phase transformation and results in the temperature of phase transformation increasing from 850℃ to 950℃. Therefore doped-CeO2 stabilizes anatase titanium oxide.Crystal structure of titanium oxide is nearly connected with property. In crystal lattice of anatase titanium oxide, there are more defect and dislocation network, which results in more oxygen vacant site to capture electron. So anatase titanium oxide can separate electrum and cavity more effectively. At the same time, anatase has better photoactivity than rutile. Therefore it is significant to research how to prepare stable anatase titanium oxide film. On the other hand, titanium oxide absorbs ultraviolet light strongly (absorption edge is at 380nm) but visible light weakly. TiO2 must be excited by high-energy ultraviolet. But because only 3-4 percent ultraviolet light of solar energy can be used by people and ultraviolet light is expensive, it is necessary to red shift exciting light from visible light to ultraviolet light, which can reduce cost and economize energy.