Berlin 2012 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 37: Poster II: Focused electron beam induced processing for the fabrication of nanostructures (focused session, jointly with O); Nanoengineered thin films; Layer properties: electrical, optical, and mechanical properties; Thin film characterization: structure analysis and composition (XRD, TEM, XPS, SIMS, RBS,..); Application of thin films

DS 37.10: Poster

Donnerstag, 29. März 2012, 15:00–17:00, Poster E

Photocurrent in sputtered TiO₂ thin films: Investigation of the influence of the measurement ambient on the electronic properties in view of its photocatalytic activity — •Alexandra K. Yatim, Dominik Wagner, Azza Amin, and Matthias Wuttig — I. Institute of Physics IA, RWTH Aachen University, Germany

Titanium dioxide (TiO₂) is a material used in many products of our daily life. However, one of its most attractive qualities is its photocatalytic activity. Since TiO₂ furthermore provides a large refractive index and a high transmittance in the visible spectral region, it has become the material of choice in the fabrication of self-cleaning coatings in the architectural glazing industry. Interestingly, although products already exist on the market, little is known about the underlying mechanism governing the strong photocatalysis. Furthermore, there is no scientific consensus about the functional principle of the self-cleaning and pollution-decomposing effect of TiO₂-coated surfaces. These effects are based on the generation of electron-hole pairs by UV illumination. Although photocurrent measurements are a bulk-sensitive method due to the detection of all free photo-generated charge carriers in the film, the measurements show that the atmosphere has a decisive impact on the photocurrent. This is plausible since the photocatalytic self-cleaning implies the decomposition of adsorbates on the surface, which is accomplished by the diffusion of the charge carriers to the surface. These charge carriers then do not contribute to the current any more. In order to evaluate the influence of ambient air, the electronic processes in TiO₂ at different oxygen partial pressures have been analysed.