Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.94: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

The Two-Dimensional Electron System Sn/Si(111) Investigated by Scanning Tunneling Microscopy — •Thomas Schramm, Philipp Höpfner, Maximilian Herpich, Jörg Schäfer, and Ralph Claessen — Experimentelle Physik 4, Universität Würzburg, 97074 Würzburg

The confinement of electrons to two dimensions may lead to strong electron correlation effects, including a Mott transition. Such two-dimensional electron systems (2DES) can be realized by adsorbing layers of metal adatoms with less than 1 monolayer thickness on (111) semiconductor surfaces. Examples include Pb and Sn on Ge(111) and Si(111) which form a √3×√3-reconstruction upon deposition of 1/3 monolayer of metal. Recent results from scanning tunneling microscopy (STM) and angle-resolved photoelectron spectroscopy provide evidence of a phase transition to a Mott-insulating ground state [1]. Moreover, the triangular lattice in the presence of correlations leads to magnetic frustrations. We have studied the formation of the √3×√3-Sn/Si(111) structure by (STM) and scanning tunneling spectroscopy experiments. Our refined surface preparation leads to perfectly √3×√3-reconstructed surfaces with low defect densities and long range order. The understanding of defect formation is of foremost importance, as this may lead to unintentional doping effects that influence a potential Mott transition. Current studies are underway, and will give a more defined insight into the correlation effects at low temperature.

[1] Modesti et al., Phys Rev. Lett. 98, 126401 (2007).