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 41.21: Poster

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

Structural and electronic characterization of ultra thin MgO films on Mo(100) by scanning tunneling spectroscopy — •Christian Pauly, Martin Grob, Mike Pezzotta, Marco Pratzer, and Markus Morgenstern — II. Physikalisches Institut B and JARA-FIT, Otto-Blumenthal-Straße, RWTH Aachen, 52074 Aachen

We investigated MgO films on Mo(100) with a thickness of up to 11 monolayers (ML) by scanning tunneling microscopy (STM) and spectroscopy at room temperature. The MgO films were prepared by evaporation of magnesium in oxygen atmosphere.
The appearance of the MgO islands (e.g. island heights) imaged by STM strongly depends on the applied bias voltage at the onset of the conduction band. In particular, the edges appear brighter than the interior of the islands, which we attribute to a spectroscopic effect probably related to defects. The characteristic moiré pattern caused by the lattice mismatch of Mo and MgO has been found on up to 11 ML thick MgO islands. The width of the band gap was measured with respect to the film thickness by dI/dU-spectroscopy. The MgO films partly show a characteristic peak in the band gap, which could be assigned to charged defect states.