High-rate deposition of photocatalytic TiO2 films by oxygen plasma assist reactive evaporation method

High-rate deposition of titanium dioxide (TiO2) film was attempted using oxygen plasma assisted reactive evaporation (OPARE) method. Photocatalytic properties of the film were investigated. During the deposition, the substrate temperature was fixed at 400 °C. The film deposition rate can be increased by increasing the supply of titanium atoms to the substrate, although oversupply of the titanium atoms causes oxygen deficiency in the films, which limits the deposition rate. The film structure depends strongly on the supply ratio of oxygen molecules to titanium atoms O2/Ti and changes from anatase to rutile structure as the O2/Ti supply ratio increased. Consequently, the maximum deposition rates of 77.0 nm min− 1 and 145.0 nm min− 1 were obtained, respectively, for the anatase and rutile film.Both films deposited at such high rates showed excellent hydrophilicity and organic decomposition performance. Even the film with rutile structure deposited at 145.0 nm min− 1 had a contact angle of less than 2.5° by UV irradiation for 5.0 h and an organics-decomposition performance index of 8.9 [μmol l− 1 min− 1] for methylene blue.