Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 63: Semiconductor substrates: Adsorption
O 63.2: Vortrag
Freitag, 27. März 2009, 11:30–11:45, SCH A118
Self assembled organic monolayers on silicon carbide — •Marco Hoeb, Ian D. Sharp, Carlos A. Diaz Alvarez, Sebastian Schoell, Martin Stutzmann, and Martin S. Brandt — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany
Because of its remarkable properties such as its biocompatibility or the possibility of bandgap engineering using its different polytypes, silicon carbide (SiC) is a promising substrate material for applications in the field of biosensors. One requirement for stable biosensors based on organic-inorganic hybrids is a covalent attachment of functional organic layers to the semiconductor surface. Here, we demonstrate high quality monolayers of 1-octadecene (C18H36) on both Si- and C-polar 6H-SiC surfaces. Organic monolayer self-assembly in the well-known case of silicon is typically achieved via hydrosilylation, a process where a hydrogen-terminated surface is required. The double-bonded carbon atom of the alkane directly attaches to the silicon surface and results in a Si-C bond. In contrast, SiC surfaces are OH-terminated following etching in hydrofluoric acid and are, therefore, in principle not appropriate for this reaction. Nevertheless, the hydroxylated surfaces form dense and chemically stable alkene layers on both crystal faces. We show by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy that the bridging between the organic molecule and SiC occurs via an oxygen atom that is not present in the case of hydrosilylated silicon. We discuss this reaction in the framework of Markownikow addition.