High-Rate Deposition of Titanium Dioxide Films with Photocatalytic Activities by Gas Flow Sputtering

Kiyoshi ISHII  Kazunari KUROKAWA  Sachio YOSHIHARA  

IEICE TRANSACTIONS on Electronics   Vol.E87-C   No.2   pp.232-237
Publication Date: 2004/02/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Oxide Thin Films by Sputtering)
titanium dioxide film,  photocatalytic activity,  sputtered film,  gas flow sputtering,  

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Photocatalytic TiO2 films were prepared by reactive gas flow sputtering (GFS), which enables sputter-deposition at a high pressure of about 100 Pa. A pure Ti tube was used as the target, and the O2 gas was supplied in front of the substrate, resulting in a very stable discharge and a high deposition rate of 80 nm/min. The crystal structure and morphology of TiO2 films were found to strongly depend on the flow rate of O2 gas during sputtering. Polycrystalline films composed of rutile and anatase crystallites were deposited at a low O2 flow rate of less than 2 sccm when Ar flow rate was set at 300 sccm, and amorphous films were deposited at higher O2 flow rates. Polycrystalline films composed of very small crystallites showed high levels of photocatalytic activity, while amorphous films showed no activity.