Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.29: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Large Area Growth of Pt-induced Atomic Nanowires on Ge(001) — •Sebastian Meyer¹, Kathrin Roensch¹, Marc Wisniewski¹, Christian Blumenstein¹, Jörg Schäfer¹, Andrej Stekolnikov², Fiedhelm Bechstedt², and Ralph Claessen¹ — ¹Physikal. Institut, Universität Würzburg, 97074 Würzburg — ²Inst. f. Festkörpertheorie u. -optik, Universität Jena, 07743 Jena

The structural properties of atomic nanowires are closely affecting both self-organized growth and resulting conduction behavior. A fascinating case are Pt nanowires on the Ge(001) surface. A dimerization along the chains observed in scanning tunneling microscopy (STM) is reminiscent of a charge density wave. However, sideways dimer elements also exist, which indicate dimerized back-bonds. Near the Fermi level, dimerization is not observed, and a spatially rather uniform charge density exists. It is consistent with metallic character at room temperature, as is confirmed by tunneling spectroscopy. Concerning the bonds involved, rather high substrate temperatures (∼700 ^∘C) are needed to initiate large-area growth. The experimental findings can be understood within a structural model obtained from ab-initio simulation [1]. It turns out that Pt-Ge bonds are favored. Moreover, the prominent dimerization along the chain is explained by Ge dimers rather than Pt ones. Instead, the metal atoms are incorporated as chain of alternating Pt and Ge atoms adjacent to the top ridge. Such complex bond rearrangement makes it plausible that high activation energies are needed for a structural reorganization.

[1] A. A. Stekolnikov et al., Phys. Rev. Lett. 100, 196101 (2008).