Dresden 2011 – scientific programme
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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 60.52: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Ambipolar doping in quasi-free epitaxial graphene on SiC(0001) controlled by Ge intercalation — •Konstantin Emtsev1, Alexei Zakharov2, Camilla Coletti1, Stiven Forti1, and Ulrich Starke1 — 1Max-Planck Institute for Solid State Research, Stuttgart, Germany — 2MAX Lab, Lund University, Lund, Sweden
Growth of graphene on single crystals of SiC is considered among the most promising routes for large scale graphene fabrication [1]. Recently we have shown that the electronic structure of graphene on SiC(0001) can be tailored by controlling the atomic structure of the interface [2]. In the present work we utilized the intercalation phenomenon to introduce atomically thin layers of germanium at the interface between the graphene-like (6√3×6√3)R30∘-reconstructed buffer layer and the SiC surface. The expanded interface decouples the graphene from the SiC surface structurally and electronically. A quasi-free standing graphene monolayer develops and shows moderate p- or n-doping depending on the amount of Ge intercalated. We present a detailed study of the structural and electronic properties of such films. The samples were characterized by high resolution ARPES and XPS. In addition, microscopic properties of Ge-intercalated graphene films were investigated in detail by means of low-energy electron microscopy (LEEM). Importantly, relatively low temperatures required for the intercalation have enabled us to capture the transformation process by LEEM in situ in real-time. [1] P.N. First et al., MRS Bulletin, 35, 296 (2010). [2] C. Riedl et al., Phys. Rev. Lett. 103, 246804(2009)