Regensburg 2000 – scientific programme

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.55: Poster

Monday, March 27, 2000, 19:00–22:00, Bereich C

Isopropoxy induced stabilisation of the 2x1 reconstruction of Si(100) — •T. Heller1, A. Lopez2, T. Bitzer2, N.V. Richardson2, and D. Schmeißer11BTU Cottbus, LS Angewandte Physik Sensorik, Erich-Weinert-Str. 1, 03046 Cottbus, Germany — 2School of Chemsitry, St. Andrews University, KY16 9ST UK

Alcohols are successfully employed as an additive in the anisotropic etching of silicon. In this HREELS study, we modelled the silicon/etching interface by the adsorption of alcohols (ethanol, isopropanol, n-propanol, tert-butyl alcohol) on Si(100)-2x1 and post-exposure to H2O under ultra high vacuum conditions. The vibrational data show that the adsorption of the alcohol molecules involves the cleavage of the O-H bond and the formation of a Si-O-C linkage to the alkoxy species. The dissociated hydrogen saturates one of the neighbouring dangling Si bonds. The Si-Si dimer bonds are not involved in the adsorption process. We observe a considerable chemisorption of water on the ethoxy and tert-butoxy passivated Si(100)-2x1 surface. From the disappearance of the 2x1 LEED pattern it can be concluded that the chemisorption of water occurs through a cleavage of the Si-Si dimer bond. In contrast, isopropoxy species on Si(100)-2x1 reduces dramatically the reactivity of Si(100)-2x1 towards water. Even following extreme exposures to water (1012 Torr s), a 2x1 LEED pattern was observed indicating the presence of intact Si-Si dimer bonds at the isopropoxy/Si(100)-2x1 surface.

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