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 (O-2) 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 x 10(-4) Torr (0.7 x 10(-2) Pa) O-2 pressure. However, the film deposited without O-2 Supply contains some amorphous TiO2-x species, which retard apparently the hydrophilicity. When the O-2 supply is increased over 0.5 x 10(-4) Torr, the films become amorphized TiO2 gradually, reaching an amorphous structure at 2.0 x 10(-4) Torr (2.7 x 10(-2) Pa). The films deposited above 0.5 x 10(-4) Torr O-2 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. (C) 2003 Elsevier B.V. All rights reserved.