Structure and hydrophilicity of titanium oxide films prepared by electron beam evaporation

Titanium oxide films were deposited in an electron-beam evaporation system using rutile TiO2 as a source material. The films deposited with various oxygen (O2) pressures were investigated by X-ray diffraction patterns, Raman, UV–Vis absorption, X-ray photoelectron spectra and atomic force microscopy. The UV-induced hydrophilicity of the films was measured by the water contact angle variation. The best hydrophilicity was obtained on the well-crystallized anatase TiO2 film deposited with 0.5 × 10−4 Torr (0.7 × 10−2 Pa) O2 pressure. However, the film deposited without O2 supply contains some amorphous TiO2−x species, which retard apparently the hydrophilicity. When the O2 supply is increased over 0.5 × 10−4 Torr, the films become amorphized TiO2 gradually, reaching an amorphous structure at 2.0 × 10−4 Torr (2.7 × 10−2 Pa). The films deposited above 0.5 × 10−4 Torr O2 show a comparable UV-induced hydrophilicity, and the amorphized TiO2 component in the films make their UV-induced hydrophilicity somewhat inferior to the well-crystallized anatase TiO2 film.