Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Metallic Nanowires on Semiconductor Surfaces
O 18.3: Poster
Montag, 7. März 2016, 17:00–19:30, Poster A
Structural and electronic instabilities in Si(hhk)-Au — •Marvin Detert, Timo Lichtenstein, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover
For future plasmonic devices understanding at 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. All measurements were performed at a base pressure of 5× 10−11 mbar by an electron energy loss spectrometer combined with a setup of spot profil analysis in low energy electron diffraction providing both high momentum and energy resolution.
As long time measurements showed a time dependent shift of the plasmon dispersion for Si(hhk)-Au at various Au coverages, the plasmonic excitations in Si(775)-Au and Si(553)-Au, particularly the dispersion relation and its time dependence, were investigated. Primarily we took special care to eliminate water and hydrogen from the background gas. We found that the plasmon dispersion remains unchanged over time for a coverage of 0.48 ML for Si(553)-Au and a coverage of 0.32 ML for Si(775)-Au. Therefore, at these coverages all dangling bonds seem to be saturated. At other coverages, thermal desorption spectroscopy shows mainly an H2 peak at 580 ∘C. Therefore, we conclude that atomic hydrogen generated by the electron beam leads to a modification of structural and electronic properties.