Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 37: Posters: Plasmonics, Electronic Structure and Spin-Orbit Interaction, Semiconductor and Insulator Surfaces, Nanostructures
O 37.96: Poster
Dienstag, 1. April 2014, 18:30–22:00, P2
Vibration modes of Si(111)-(7×7) and various reconstructed Au/Si(111) surfaces, studied by Raman spectroscopy — Martin Liebhaber1, Utz Bass1, •Jean Geurts1, Jochen Räthel2, Eugen Speiser2, Sandhya Chandola2, Arne Baumann2, and Norbert Esser2 — 1Universität Würzburg, Physikalisches Institut, Experimentelle Physik III, 97074 Würzburg — 2Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., 12489 Berlin
Ordered submonolayers of adsorbate atoms on semiconductor surfaces constitute a playground for electronic correlation effects, which are tightly connected with the local atomic arrangement and the corresponding vibration modes. We applied polarized Raman spectroscopy to Au-covered Si(111) surfaces, either with (5×2) or with (√3×√3) reconstruction, and to clean Si(111)-(7×7) surfaces for reference. On the latter ones, six surface vibration modes appear between 7.7 meV and 52.1 meV, with different polarization dependence. Upon Au coverage, they are quenched and replaced by new modes, governed by the specific Au reconstruction. For (5×2), five low-frequency Au-induced vibration modes emerge (3.2 meV to 18.7 meV). The (√3×√3) Au reconstruction shares two of them, but also shows two new peaks in the same range. For the clean Si(111) (7×7) surface, these results should enable refined calculations of the dynamic properties of the DAS structural model. For the Au-covered surfaces, the reconstruction-specific vibrations may help to clarify the atomic geometry, extending the base for more sophisticated calculations of atomic and orbital properties of ordered adatom arrangements for correlated-electron systems.