Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 22: Epitaxie und Wachstum I
O 22.11: Vortrag
Dienstag, 25. März 2003, 17:30–17:45, FOE/ORG
Preparation and characterization of thin crystalline vanadiumoxide films on V75Ru25(110) — •Jürgen Middeke, Ralf-Peter Blum, Frank Balzer, and Horst Niehus — Humboldt-Universität zu Berlin, Institut für Physik, ASP, Invalidenstr. 110, 10115 Berlin
We investigate the growth of 2-dim vanadiumoxide films on V75Ru25(110) in ultra high vacuum with scanning tunneling microscopy (STM), impact collision ion scattering spectroscopy with detection of neutrals (NICISS), low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). Investigations with NICISS show that the clean V75Ru25(110) surface consists of 50% vanadium and 50% ruthenium with an ordered surface structure. The surface was oxidized by oxygen exposure introduced at elevated sample temperatures, leading to films containing only vanadiumoxide and no rutheniumoxide. The beginning of the oxide growth is found for oxygen doses of 2...10 Langmuir at a pressure of 10−8mbar and a temperature of 900K, where we get different structures depending on the exact preparation conditions. Exposition to 300 Langmuir at 10−6mbar and 900K results in an oxide layer of more than 10nm thickness that does not show any signal from ruthenium in AES, leading to the conclusion that the oxide growth is not a self-terminating process. This thick layer shows a hexagonal structure similar to that known from V2O3(0001), but it also contains a dislocation network that might be considered to be useful in catalytic research.