Influence of Annealing Temperature on the Microstructure of TiO_2 Nanometer Thin Films

The influence of annealing temperature on the microstructure and surface morphology of TiO2 nanometer thin films prepared by sol-gel method were studied. The microstructure and surface morphology were examined by XRD、IR、 UV-VIS、AFM and XPS. The film was consisted of anatase and rutile phase annealed at 450℃ to 600℃. After being annealed at 700℃, the structure of TiO2 thin film changed into rutile completely. In the film, besides Ti and O elements, there are a certain amount of residual carbon from the starting organometallic components and a small amount of sodium ions diffused from the glass substrates. The refraction index (n) increases from 1.944 to 2.037 as the anneal temperature increasing (350~500 ℃) and the indirect optical absorption band gaps (Eg) decreases from 3.58 eV to 3.26 eV as anneal temperature increasing (350~650℃). AFM result shows that the RMS of films is about 2~3 nm.