Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)
O 17.73: Poster
Montag, 26. März 2007, 17:30–20:30, Poster C
Adsorption of molecular hydrogen on SiC(001), Si(001) and C(001) surfaces: An ab-initio investigation — •Xiangyang Peng, Peter Krüger, and Johannes Pollmann — Institut für Festkörpertheorie, Wilhelm-Klemm-Str. 10, 48149 Münster
In experiment, the exciting observation has been made that H2 molecules readily adsorb dissociatively on the c(4×2) but not on the 3×2 surface of SiC(001) at room temperature. To unravel this spectacular reactivity difference, we have investigated a variety of H2 reaction scenarios within density functional theory using the generalized gradient approximation. It turns out that intradimer adsorption is unlikely at both surfaces while interdimer adsorption depends crucially on the distinct spatial arrangement and dangling-bond topology of the Si dimers at the surfaces. The results clearly reveal barrierless reaction pathways for dissociative H2 adsorption on the c(4×2) surface as opposed to pathways with significant energy barriers on the 3×2 surface. The latter finding also allows us to explain the inertness of self-organized Si addimer nanolines on the c(4×2) surface to H2 uptake. To better understand the influence of the surface atomic structure and the dangling-bond topology on H2 adsorption at group IV semiconductor surfaces, we have investigated the adsorption of H2 molecules on Si(001) and C(001), as well.