Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 33: Oxides and Insulators: Epitaxy and Growth

O 33.8: Talk

Tuesday, March 27, 2007, 17:30–17:45, H41

The initial stages of Chromium growth on Titaniumdioxide-Investigations using synchrotron radiation — •Sebastian Müller and Dieter Schmeißer — Brandenburgische Technische Universität Cottbus, Lehrstuhl Angewandte Physik-Sensorik, Postfach 10 13 43, 03013 Cottbus

We investigate the interface of Cr-TiO₂ during the initial stages of Cr deposition. Experiments are carried out at BESSY II (BL U49/2-PGM2). Using XPS, XAS and ResPES we obtain information about electronic structure at the interface. We confirm the results of growth studies by Christian Winde obtained by TEM-EELS. In addition, we find that Cr deposition induces two gap states which appear about
1 eV and 3 eV below E_F. Using ResPES, these states can be identified as being Cr-like and Ti-like respectively. Core-level-XPS and CIS-spectra of the lower gap state indicate the existence of mainly Cr⁴⁺ at low coverage (< 1 ML).

At higher coverage (≈ 2.5 ML) metallic Cr is observed as well as metallic Ti. Oxidized Cr occurs mainly as Cr³⁺. CIS-spectra of higher gap state show metallic behavior with both Cr- and Ti-like character. CIS-spectra of lower gap-state confirm the existence of Cr³⁺.

Reference: Christian Winde, Herstellung und Charakterisierung von Cr Schichten auf TiO₂ (110)Oberflächen, PhD Thesis, University of Stuttgart, 2002