Product Code: ICA10_P142

Photoconductive Properties of Titanium Dioxide Film by Femtosecond Laser Irradiation
Authors:
Teppei Nomura, Graduate School of Enginering, Osaka University; Suita, Osaka Japan
Masahiro Tsukamoto, Joining and Welding Research Institute Osaka University; Ibaraki, Osaka Japan
Masanari Takahashi, Osaka Municipal Technical Research Institute; Osaka, Japan Japan
Masayuki Fujita, Institute for Laser Technology; Osaka, Japan Japan
Nobuyuki Abe, Joining and Welding Research Institute Osaka University; Ibaraki, Osaka Japan
Presented at ICALEO 2010

Titanium dioxide (TiO2) is functional ceramics and shows the photoconductive property by ultraviolet (UV) light illumination. In our previous study, we fabricated TiO2 films with an aerosol beam and the films were irradiated with femtosecond laser. The TiO2 film was darkened after the laser irradiation. The electrical resistance of TiO2 films were decreased by the laser irradiation although laser ablation did not occur. It is reported that oxygen deficiencies in TiO2 might be the cause for the darkening. However, the photoconductive property of TiO2 films darkened by the femtosecond laser irradiation was not investigated. There is a possibility that darkened TiO2 film shows a visible light sensitivity, althogh raw TiO2 film has only an UV light sensitivity.
In this study, we investigated variation of the photoconductive property of TiO2 films after the femtosecond laser irradiation. The wavelength, the pulse width and the repetition rate of the femtosecond laser were 775 nm, 150 fs and 1kHz, respectively. In the experiment, the laser spot was scanned on the TiO2 film surface and the laser fluence was changed within the laser fluence range in which the laser ablation was not caused and morphology of the TiO2 film surface was not varied. The photoconductive property of TiO2 films is evaluated with measuring the electrical resistance under UV and visible light illumination. The electrical resistance of darkened TiO2 films decreased with increasing illumination time of visible light.