Paper TF-ThP15
Photo-functional Properties for Fe-Added Titanium Dioxide Thin Films Prepared by Reactive Magnetron Sputtering

Thursday, October 21, 2010, 6:00 pm, Room Southwest Exhibit Hall

Since the photoinduced decomposition of water on TiO₂ electrodes were discovered, semiconductor based on photocatalyst has attracted extensive interest. TiO₂ is anticipated as one of materials which are alternative for existing solar cell technology type based on a silicon type. TiO₂ shows relatively high reactivity and chemical stability under UV light whose energy exceeds the band gap of 3.2 eV in the anatase crystalline phase. The sun can provide an abundant source of photons. However, UV light accounts for the only small fraction (~5 %) of the sun’s energy compared to the visible region (45 %). Many techniques have been examined to achieve this purpose, including the doping of TiO₂ with transition metals (such as Cr, Fe, Ni, V).

In this study, TiO₂ film has been prepared by reactive magnetron sputtering using a Ti target in an Ar/O₂ gas mixture. Fe addition was performed by Fe sputtering onto those TiO₂ films. Composition and microstructure of these films were investigated by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. Chromatic change of a methylene blue solution was applied to a photocatalytic property. Light irradiation to the TiO₂ film in a methylene blue solution was carried out using a commercial sterilizing lamp as ultraviolet light and artificial sun light as visible light. Transmittance of a methylene blue solution was measured by a spectrophotometer. Furthermore, photocurrent between the TiO₂ film and a platinum electrode was measured by a volt-ampere characteristic using an unresisted ammeter in a KCl solution of 0.5 mol/ℓ.

The crystal structure of TiO₂ turned from a ruttile type into an anatase type with increase of O₂ gas flow rate. Photocatalytic characteristic of an anatase type showed the higher value under ultraviolet light, while the difference in the crystallographic structure was not obserbed under visible light. The effect of adding Fe was obtained at the Fe-added sample basing TiO₂ prepared with O₂ gas flow rate of 1.5 and 2.0 sccm. It was considered that the charge separation between an electron and a hole was enhanced by adding Fe to the TiO₂ surface. The optimum thickness of the Fe film was about 0.1 nm.