Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 30: 1D Metal Wires on Semiconductors I

O 30.1: Vortrag

Dienstag, 8. März 2016, 10:30–10:45, S052

One dimensional plasmons in Si(hhk)-Au — •Timo Lichtenstein¹, Marvin Detert¹, Julian Aulbach², Jörg Schäfer², Christoph Tegenkamp¹, and Herbert Pfnür¹ — ¹Institut für Festkörperphysik, Leibniz Universität Hannover — ²Physikalisches Institut and RCCM, Universität Würzburg

For future plasmonic devices the understanding of low dimensional collective excitations is indispensable. For quasi one dimensional (1d) structures Au induced wires on regularly stepped Si(hhk) offer the perfect playground. Therefore, Si(553) and Si(775) were prepared at coverages where both surfaces host a double atomic gold chain per terrace. The wire quality was checked with spot profile analysis in low energy electron diffraction (SPA-LEED). A combination of an electron energy loss spectrometer and SPA-LEED providing both high energy and momentum resolution gave access to the plasmon dispersion.

Although 1d metallicity is observed, the plasmon dispersion strongly depends on a two-dimensional crossover: on the lateral distribution of the 1d electron density of states (DOS) within one terrace (intrawire correlation), as well as on the spacing of the wires (interwire correlation). This can quantitatively be described by a modified plasmon model for a wire array. We obtained effective widths of 7.5 Å for Si(553)-Au and 10.2 Å for Si(775)-Au, which are considerably smaller than the terrace widths. A modulated DOS of comparable width can also be seen by tunneling spectroscopy. These effective widths seem to be influenced both by the structural motif, i.e. single or double chain, as well as by the terrace size.