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approvedosiabstractraman_2_fin.pdf2015-05-18 05:26:26Norbert Esser


Author: Norbert Esser
Requested Type: Oral
Submitted: 2015-05-18 05:23:31

Co-authors: E. Speiser, S. Chandola, J. Raethel, J. Plaickner

Contact Info:
Leibniz-Institut für Analytische Wissenschaften
Schwarzschildstrasse 8
Berlin,   12489

Abstract Text:
The development of increasingly small devices and wires in the field of nano electronics makes it necessary to study new physical phenomena that arise from the high electron correlation resulting from the reduced size and dimensionality of these systems. We use Raman spectroscopy (RS) and Reflectance Anisotropy Spectroscopy (RAS) to investigate the vibrational and optical properties of metallic nanowire systems on semiconductor surfaces. In particular we demonstrate that Raman spectroscopy applied to semiconductor surfaces in UHV is a versatile method to record surface localized phonon modes which are related to the surface atomic structure. Thus, in particular in combination with DFT based modelling of surface vibrations Raman spectroscopy becomes a versatile method to derive structure information from surfaces.
Several systems will be discussed such as clean Si(111) and Au on Si(111) and Si(553) surfaces. Au adsorbates in the (sub-)monolayer coverage range induce specific ordered structures (nanowires) on these surfaces, being very distinct from the clean surfaces. The vibrational properties of the respective clean and metal terminated surfaces were characterized with polarized RS and related surface phonon modes identified. Surface vibrational modes are separated from bulk phonon modes by modifying the surface, e.g. by oxidation, and taking difference spectra.