Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.40: Poster

Montag, 8. März 2004, 18:00–21:00, Bereich C

Au/Si(111): Local ordering of the (5×2) reconstruction — •C. Seifert, F.-J. Meyer-zu Heringdorf, and M. Horn-von Hoegen — Inst. für Laser- und Plasmaphysik, Universität Duisburg-Essen (Campus Essen)

At Au coverages ΘAu<1/3ML and substrate temperatures above 300C, Si(111) surfaces exhibit a striped (5× 2) reconstruction, consisting of three different domains with an angle of 60 between them. Upon deposition of Au, each of the domains forms needles that grow predominantly in the 2-fold direction of the reconstruction. The resulting anisotropy is so dominating, that if one domain encounters another one with a different rotational orientation, the needle-like domain keeps growing, and can erode the other domains (1) or even completely intersect them (2). Here we discuss a combined High Resolution Low Energy Electron Diffraction (SPA-LEED) and Scanning Tunneling Microscopy (STM) experiment to understand the details of the (5× 2) reconstruction. The (5× 2) LEED pattern can be understood as a (5× 1) pattern with elongated (5× 2) spots that form stripes located at 50% Brillouin-Zone (BZ). The detailed shape of the stripes depends on the sample preparation temperature. Room temperature STM measurements combined with fourier analysis and simple simulations of the adatom arrangement indicate a local ordering of the gold adatoms.

[1] T. Hasegawa, S. Hosaka, S. Hosoki Surf. Sc. 357-358 (1996), 858-862

[2] F.-J. Meyer zu Heringdorf, R.M. Tromp, unpublished

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