Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 50: Graphene (organized by O)
TT 50.11: Poster
Tuesday, March 17, 2015, 18:15–21:00, Poster A
Polarization doping of graphene on silicon carbide — Samir Mammadov1, Jürgen Ristein2, Roland J. Koch1, Markus Ostler1, Christain Raidel1, Martina Wanke1, Remigijus Vasiliauskas3, Rositza Yakimova3, and •Thomas Seyller1 — 1Institut für Physik, TU Chemnitz, Reichenhainer Str. 70, D-09126 Chemnitz, Germany — 2Lehrstuhl für Laserphysik, FAU Erlangen-Nürnberg, Erwin-Rommel-Str. 1, D-91058 Erlangen, Germany — 3Department of Physics, Chemistry and Biology, Linköping University, SE-58183, Linköping, Sweden
Being an atomically thin layer, graphene has no bulk. Hence, the charge carier density is influenced by its environment, especially the substrate. While epitaxial graphene on SiC(0001) is n-type doped due to charge transfer from interface states [1], quasi-freestanding graphene (QFG) on H-terminated SiC(0001) is p-type doped [2]. This was explained by the spontaneous polarization of the hexagonal SiC substrate [3]. As a test, we have carried out angle-reolved photoelectron spectroscopy of QFG on H-terminated 3C-SiC(111), 6H-SiC(0001), and 4H-SiC(0001). Using semi-insulating and n-type substrates we shed light on the contributions to the charge carrier density in QFG caused by the spontaneous polarization of the substrate, and the band alignment between the substrate and the graphene layer. In this way we provide quantitative support for the polarization doping model.
[1] S. Kopylov et al., Appl. Phys. Lett. 97 (2010) 112109. [2] F. Speck et al., Appl. Phys. Lett. 99 (2011) 122106. [3] J. Ristein et al., Phys. Rev. Lett. 108 (2012) 246104.