Paper SS-TuP11
Photo-functional Property of TiO₂/Cu₂O and TiO₂/TiN/Cu₂O Thin Films by Reactive Magnetron Sputtering

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Characteristics based on photo-inducement of TiO₂ have attracted various interests in many fields. TiO₂ has been known as one of a promising photocatalyst and is already used in various practical applications, such as the degradation of environmental pollutants and the self-cleaning of glasses. Furthermore, the most important characteristic as a photocatalyst of TiO₂ is well known that photo-excited state is very stable and does not cause self-decomposition. Therefore, the electrolysis of water is performed under ultra-violet (UV) light irradiation to TiO₂. However UV energy accounts for only a small fraction (~5%) of the sun’s energy compared to the visible region (45%).

In this study, to improve the photo-functional property of TiO₂ the double layer films were fabricated by the constitution of the TiO₂ layer of an n-type semiconductor and the Cu₂O layer of a p-type semiconductor. Each arrangement of the film with TiO₂/Cu₂O was also investigated by optical permeability. Furthermore, to prevent diffusion of Cu from the Cu₂O layer to the TiO₂ layer, the TiN layer was inserted between the TiO₂ layer and the Cu₂O layer. As the following study, this Cu₂O layer was replaced to the Ag₂O layer. Those layers were fabricated by reactive magnetron sputtering. Composition and microstructure of these films were investigated by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. Chromatic change of a methylene blue solution was applied for the photocatalytic evaluation. Light irradiation to the sample in a methylene blue solution was carried out using a commercial sterilizing lamp as ultraviolet light and an artificial sun lamp as visible light. Transmittance of a methylene blue solution was measured by a spectrophotometer after irradiation for 6 hours by each lamp.

The XRD pattern of the TiO₂/Cu₂O thin film showed the strong peak of the anatase-rutile TiO₂ from an upper layer and the weak peak of Cu₂O from a lower layer. The suitable photocatalytic effect was obtained by the constitution of TiO₂ with 300 nm and Cu₂O with 200 nm in thickness, when the photocatalytic effect showed about 31 % under an artificial sun lamp and about 90 % under a sterilization lamp. In the case of the TiO₂/TiN/Cu₂O film it was estimated that the diffusion of Cu atoms was almost prevented by inserting TiN from the XRD pattern, when the photocatalytic effect showed about 39 % under an artificial sun lamp and about 89 % under a sterilization lamp.