Titanium dioxide (TiO{sub}2) films with photocatalytic activities were prepared by reactive gas flow sputtering (GFS). GFS is a high-pressure sputtering at about 100 Pa enabling high deposition rates, and it has characteristics between PVD and CVD. A pure Ti tube was used as the target and the oxygen gas was supplied in front of the substrate. A stable sputter-deposition was carried out at a deposition rate of 80 nm/min. The crystal structure and morphology of TiO{sub}2 films were found to strongly depend on the flow rate of oxygen gas. Polycrystalline films composed of rutile and anatase crystallites were deposited at a low flow rate of oxygen gas less than 2 sccm, where Ar flow rate was set at 300 sccm, and amorphous films were produced at the higher flow rates of oxygen gas. Polycrystalline films showed superior photocatalytic activities, while amorphous films were not photocatalytic.
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