High rate deposition of photocatalytic TiO₂ films by dc magnetron sputtering using a TiO_2-x target

Photocatalytic TiO₂ films were deposited on glass substrates by dc magnetron sputtering using a slightly reduced TiO_2-x target (2-x=1.986; conductivity, 3.7 S cm^-1; density, 4.21 g/cm³). The variation in the deposition rate as a function of the O₂ flow ratio did not show a hysteresis curve at the “transition region” as seen in the case of a Ti metal target. The deposition rate using the TiO_2-x target in 100% Ar gas was approximately seven times higher than that using the Ti metal target in an “oxide mode.” The films postannealed in air at temperatures ≥200 °C showed excellent photodecomposition characteristics of acetaldehyde (CH₃CHO) as well as photoinduced hydrophilicity.