Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 8: Focused Session: Epitaxial Graphene I

O 8.3: Vortrag

Montag, 23. März 2009, 12:00–12:15, SCH 251

Molecular Hole Doping and Band Structure Engineering of Epitaxial Graphene on SiC — •Camilla Coletti, Christian Riedl, Dong Su Lee, Klaus von Klitzing, Jurgen H. Smet, and Ulrich Starke — Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart

In view of its intriguing two-dimensional electron gas properties, graphene is a promising host material for next-generation electronics. In particular, graphene epitaxially grown on silicon carbide (SiC), offers realistic prospects for electronic device implementation. However, the intrinsic n-type doping and the consequent metallic nature of these epitaxial layers badly accommodate in conventional electronics. We show, via angle resolved ultraviolet photoelectron spectroscopy (ARUPS) and Raman analysis, how monolayer and few layer epitaxial graphene can be rendered truly semiconducting by functionalizing the graphene surface with the strong electron acceptor tetrafluorotetracyanoquinodimethane (F4-TCNQ). We also report how, in the case of bilayer graphene, the molecular layer influences the details of the band structure thus suggesting the possibility for band gap engineering. We provide via X-ray photoelectron spectroscopy (XPS) and valence band investigations a complete characterization of this charge transfer complex. Furthermore, by demonstrating air stability and the feasibility of implementation via wet chemistry we show that the F4-TCNQ/graphene heterostructure is extremely appealing for future, carbon based electronic applications.