Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 54: Metallic Nanowires on Semiconductor Surfaces

O 54.2: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1C

Au-chains grown on Ge(100): A detailed SPA-LEED and EELS-LEED study — •Timo Lichtenstein, Zamin Mamiyev, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover

Ge(100) is known as a substrate for self-organized growth of one-dimensional quantum wires by adsorption of Au, highly interesting for future plasmonic devices. In this study, the morphology has been investigated by means of spot profile analysis low energy electron diffraction. Using LEED in combination with an energy electron loss spectrometer we measured the plasmon dispersion relation with both high energy and momentum resolution. First, we systematically measured the properties on variously prepared surfaces. From G(S)- and H(S)-analyses on ex-situ chemically treated Ge-samples followed by multiple in-situ Ar⁺-sputtering and high-temperature annealing cycles, we were able to obtain surfaces with a terrace width of around 100 nm and low roughness After the growth of the Au-wires, this analysis favors a giant missing row structure. For Au coverages higher than 0.7 ML low-dimensional plasmon modes appear in the loss spectra. Their dispersion relation increases linearly for parallel momentum >0.1 Å⁻¹, but deviates from the typical dispersion of a quasi-one-dimensional plasmon for <0.1 Å⁻¹. These effects are possibly attributed to the strong electronic correlations of the system due to the Luttinger-liquid-like behavior inside the wires as well as the strong coupling between. Peak widths and heights of the plasmon excitations in the loss spectra reveal a low excitation probability and very short lifetimes.