Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Focused Session: Epitaxial Graphene I
O 8.2: Vortrag
Montag, 23. März 2009, 11:45–12:00, SCH 251
Atomic Hole Doping of Graphene — •Isabella Gierz1, Christian Riedl1, Ulrich Starke1, Christian Ast1, and Klaus Kern1,2 — 1Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany — 2Institut de Physique des Nanostructures, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland
Graphene is an excellent candidate for the next generation of electronic materials due to the strict two-dimensionality of its electronic structure as well as the extremely high carrier mobility. A prerequisite for the development of graphene based electronics is the reliable control of the type and density of the charge carriers. While gating has been successfully demonstrated, the development of reliable chemical doping methods turns out to be a real challenge. In particular hole doping is an unsolved issue. Here we show by angle-resolved photoemission spectroscopy (ARPES) that atomic doping of an epitaxial graphene layer on a silicon carbide substrate with bismuth, antimony or gold presents effective means of p-type doping. Bismuth and antimony are only able to reduce the substrate induced n-type doping of epitaxial graphene. Gold adatoms, however, shift the Dirac point into the unoccupied states. In combination with the intrinsic n-type character of epitaxial graphene on SiC, the charge carriers can be tuned from electrons to holes, without affecting the conical band structure.