Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.2: Poster

Montag, 25. Februar 2008, 18:30–19:30, Poster F

Self-assembled Pt nanowires on Ge(001) — •Cosima Schuster and Udo Schwingenschlögl — Institut für Physik, Universität Augsburg, D-86135 Augsburg

Semiconductor surfaces attract great attention due to various effects of self-organization. For example, adsorption of Pt on the Ge(001) surface results in stable Pt nanowires. Because self-organization of adsorpted atoms relys on strong interaction with surface states, accounting for the full structural relaxation is a prerequisite for describing the electronic properties of a covered surface in an adequate manner.

In a first step, we have thus investigated the surface electronic structure of the c(4×2) reconstructed Ge(001) surface by means of DFT band structure calculations In particular, it is possible to attribute each state to either the Ge dimer bonds or the dangling surface bonds. The Ge–Pt surface is investigated in a second step. The formation of Pt chains on Ge(001) is accompanied by the partial breakup of the Ge surface dimers. We show that the surface electronic structure is significantly perturbed due to Ge–Pt interaction. Especially, we find remarkable shifts of Ge states towards the Fermi energy. As a consequence, the topmost Ge layers are subject to a metal-insulator transition.