AVS 54th International Symposium
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuP

Paper SE-TuP4
High Rate Deposition of Photocatalytic WO3 Thin Films with Visible Light Activity by Gas-Flow Sputtering

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Session: Advanced Surface Engineering Poster Session
Presenter: M. Fukuyama, Aoyama Gakuin University, Japan
Authors: M. Fukuyama, Aoyama Gakuin University, Japan
M. Kikuchi, Aoyama Gakuin University, Japan
Y. Iwabuchi, Bridgestone Corporation, Japan
M. Yoshikawa, Bridgestone Corporation, Japan
Y. Sato, Aoyama Gakuin University, Japan
Y. Shigesato, Aoyama Gakuin University, Japan
Correspondent: Click to Email

In recent years, we have been reported on the visible-light induced photocatalytic properties on polycrystalline WO3 films deposited by reactive dc magnetron sputtering on heated glass substrate at around 600 oC.1,2 However deposition rate was very low of about 10 nm/min for the conventional reactive magnetron sputtering to deposit fully oxidized WO3 films because the films should be deposited at the "oxide mode" where the target surface is oxidized and the sputtering yield is very small. In this study, polycrystalline WO3 films were deposited by on fused quartz glass substrate by gas flow sputtering using two W metal target which were mounted parallel with each other. Ar was used as sputtering gas and O2 was used as reactive gas, which were supplied between these two targets. Total gas pressure was maintained at 70Pa. Ar and O2 gas flows were 5.0 SLM and 50 sccm, respectively. WO3 films were deposited on the substrate without heating or heated upto 500 oC, 600 oC or 700 oC. The films deposited on the unheated substrate were post-annealed at 500 oC, 600 oC or 700 oC for an hour in the air. The crystal structure of the WO3 films were analyzed by X-ray diffraction (XRD). The transmittance and reflectance of the films in UV-VIS region were measured using spectrophotometer in order to estimate absorption coefficient by Newton-Raphson’s method. The photocatalytic activity was evaluated by decomposition of acetaldehyde and contact angle for water after UV (black light lamp : 0.4mW /cm2, center wavelength : 352 nm) light and VIS (Xe lamp with a 410-500 nm band pass filter : 1.0, 7.0 mW/cm2 respectively, center wavelength : 450 nm) light irradiation. Both of the films deposited at 500-700 oC and the films post-annealed at 500-700 oC performed the visible-light induced photocatalytic activity. The highest deposition rate to deposit such photocatalytic WO3 films was 230nm/min.

1 M.Ebihara, Y.Shigesato, et al., Proceedings of the 3rd ICCG), (2000) 137.
2 M. Kikuchi, Y. Shigesato, et al., Proceedings for 6th International Conference on Coatings on Glass and Plastics (ICCG-6), (2006) 365.