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 41.115: Poster
Dienstag, 23. März 2010, 18:30–21:00, Poster B1
Band structure engineering of mono- and bilayer Graphene on SiC(0001) via molecular functionalization — •Camilla Coletti1, Christian Riedl1, Dong Su Lee1, Luc Patthey2, Benjamin Krauss1, Klaus von Klitzing1, Jurgen Smet1, and Ulrich Starke1 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany — 2Paul-Scherrer-Institut, CH-5234 Villigen-PSI, Switzerland
Although epitaxial graphene on SiC(0001) is a realistic candidate for the implementation of graphene-based electronic devices a drawback might sensibly limit its perspectives. Epitaxial graphene on SiC is in fact electron doped and consequently displays a metallic nature. Hence, the need to tailor its electronic band structure in such a way that the excess of electrons is compensated precisely to the point of charge neutrality. Noncovalent functionalization of epitaxial graphene surfaces with the strong acceptor molecule tetrafluorotetracyanoquinodimethane (F4-TCNQ) allows for a fine tuning of the doping level. Charge neutrality can be achieved for mono- and bilayer graphene as shown from ARPES and Raman spectroscopy. On bilayer samples the magnitude of the existing bandgap can be increased up to more than double of its initial value. Core level analysis and valence band investigations are used to provide a structural characterization of the charge transfer complex. The molecules are stable to air exposure, temperature resistant and can be applied via wet chemistry. Hence surface functionalization via F4-TCNQ appears to be a technologically relevant method to successfully engineer the band structure of graphene.