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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.50: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Local electronic structure of graphene on SiC(0001) studied by scanning tunneling microscopy and spectroscopy — •Thomas Druga, Martin Wenderoth, and Rainer G. Ulbrich — IV. Physikalisches Institut, Georg-August-Universität Göttingen
In this work we present a low temperature (6K) scanning tunneling microscopy study of mono- and bilayer graphene on the silicon-terminated 6H-SiC(0001) surface. The untreated crystals were electrically contacted exsitu by tantalum foils. After annealing at base pressure of 1*10−10 mbar at 500∘C for several hours the samples were graphitized between 1350∘C and 1450∘C by direct current heating. This preparation technique results in graphitized surfaces of mainly mono- and bilayer graphene up to a few hundred nm. Atomically resolved topographies of monolayer graphene show the honeycomb structure of the graphene layer, the 6x6 periodicity and disordered adatom features induced by the underlying interface layer [1]. These features have a strong influence on lateral resolved differential conductivity maps dI/dV(x,y) measured by scanning tunneling spectroscopy (STS) and demonstrate the necessity of a high lateral resolution to study the electronic properties of graphene. On bilayer graphene dI/dV - spectra show in addition to spectral features observed by other groups [e.g. 2] atomic scale modulations according to the 6x6 periodicity. This work was supported by the DFG as part of SFB 602 Tp A7.
[1] Rutter et al. Phys. Rev. B 76, 235416 (2007) [2] Lauffer et al. Phys.Rev. B 77, 155426 (2008)