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O: Fachverband Oberflächenphysik

O 96: Metallic Nanowires on Semiconductor Surfaces

O 96.5: Vortrag

Donnerstag, 23. März 2017, 16:00–16:15, WIL C107

Tuning of 1D Plasmon properties on Si(hhk)-Au by adsorbates — •Zamin Mamiyev, Timo Lichtenstein, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover, Hannover, Germany

Gold-induced atomic wires on Si(hhk) surfaces possess intriguing properties of collective electron excitations which are strongly responsive to the electronic state and also to structural motifs. The modification and control of plasmonic excitations in metallic nanowires are of particular interest due to their fundamental and technological importance. In this work, the effect of O₂ and H₂ adsorption on the plasmons in arrays of single [Si(557)-Au] and double chains of gold [Si(553)-Au] have been examined by Electron Energy Loss Spectroscopy with high resolution both in energy and momentum. Theoretical results show that oxygen and hydrogen atoms bind preferably not to the Au chains directly, but to adjacent Si-honeycomb chains (Si-HC) and Si-adatom rows (The latter exist only in Si(557)-Au). The Si-HC turns out to be mostly responsible for the plasmonic changes. While atomic H reduces the plasmon frequency on Si(553)-Au, as predicted theoretically, adsorbed oxygen leaves it unchanged, whereas a frequency increase is found to be induced by oxygen in Si(557)-Au, indicating an enhanced electron density in the partially filled surface band(s). Comparing the oxygen results on Si(553)-Au and Si(557)-Au, both the structural motifs (double vs. single chain), as well as electronic distribution across the terraces play a role. These effects still need further detailed consideration in order to separate them clearly.