Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 52: Graphene II

O 52.2: Talk

Wednesday, March 24, 2010, 15:15–15:30, H31

Decoupling epitaxial graphene from SiC(0001) surface by a germanium buffer layer — •Konstantin Emtsev and Ulrich Starke — Max-Planck Institute for Solid State Research, Stuttgart, Germany

Epitaxial graphene layers formed on SiC surfaces are currently intensively investigated with respect to their electronic, structural, and electrical transport properties [1]. On the SiC(0001) surface graphene layers are separated from the substrate by an interfacial carbon layer. The latter has a graphene-like atomic arrangement with complex (6√3×6√3)R30^∘ periodicity but lacks characteristic π-bands due to strong hybridization with the substrate [2]. In this work we demonstrate that the interfacial layer can be converted into quasi-freestanding graphene upon intercalation of Ge atoms at the interface. The electronic properties of the surface and the atomic structures of the newly formed interfaces were characterized by ARPES, XPS, and LEED. Deposition of germanium on the 6√3 reconstructed SiC(0001) surface and subsequent annealing steps were carried out in UHV following Kubler et al. [3]. Decoupling of the interface layer by intercalating Ge atoms begins at temperature of about 700^∘C as evident by the development of the electronic band structure characteristic of graphene. Depending on the amount of Ge deposited as well as on the annealing temperature the graphene layer exhibits electron or hole doping.

[1] Th. Seyller et al., Phys. Stat. Sol.(b), 245, 1436 (2008).

[2] K. V. Emtsev et al., Phys. Rev. B, 77, 155303 (2008).

[3] L. Kubler et al., Phys. Rev. B, 72, 115319 (2005).