AVS 52nd International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoP

Paper AS-MoP18
Sputtering Pressure Dependent Photocatalytic Properties of TiO@sub2@ Thin Films

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Aspects of Applied Surface Science Poster Session
Presenter: T. Takahashi, Toyama University, Japan
Authors: T. Takahashi, Toyama University, Japan
K. Prabakar, Toyama University, Japan
T. Nezuka, Toyama University, Japan
T. Nakashima, Kashiwa Chuo High School, Japan
Y. Kubota, Yokohama City University, Japan
A. Fujishima, Kanagawa Academy of Science and Technology, Japan
Correspondent: Click to Email
Titanium dioxide (TiO@sub2@) has been well-known as a photocatalyst. The objective of this research was to study the photocatalytic degradation of methanol and methylene blue at different light intensity and concentration by the effect of TiO@sub2@ thin film deposition parameters. The TiO@sub2@ films were deposited on glass substrate by direct current reactive magnetron sputtering under various total sputtering gas pressures (P@subS@) of 0.2, 0.5, 0.8 and 5 Pa and at the target to substrate distance (D@subT-S@) of 40 and 70 mm respectively with oxygen argon flow ratio 7:3 and 8:2 to find the optimum conditions to deposit the films with high photocatalytic activities. Structural factors dominating the photocatalytic activities were investigated in detail in relation to the sputter deposition processes. The films deposited at P@subS@ of 0.2 and 0.5 Pa and D@subT-S@ of 40 mm showed polycrystalline anatase structure, but, in the case of D@subT-S@ as 70 mm, only the film deposited at P@subS@ of 0.2 Pa showed the polycrystalline anatase structure. The films deposited at P@subS@ of 0.2 and 0.5 Pa showed decreasing tendency in the optical band gap energy and performed high photocatalytic activities. Such enhancement of the photocatalytic activity was considered to be correlated with the less number of defect level generations caused by the bombardment of the high-energy particles due to the long mean free path. The band gap energy was found to decrease from 3.4 to 3.1 eV for the TiO@sub2@ films deposited at lower P@subS@ as well as the D@subT-S@ was 40 mm, because of the higher crystallinity compared to the films deposited at high pressures and longer D@subT-S@. In addition to this, the films deposited at D@subT-S@ of 70 mm showed the decrease in density consequently increase in the optical band gap energy. The efficiency of the TiO@sub2@ catalysis was studied to evaluate the economic viability of this technique.