Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 72: Graphene: Adsorption, Intercalation and Doping
O 72.6: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Investigation of the molecular doping of graphene on 6H-SiC(0001) — •Christian Raidel1, Christian Heidrich1, Julia Krone1, Florian Speck1, Peter Wehrfritz1, Felix Fromm1, Roland J. Koch1, Peter Robaschik2, Francisc Haidu2, Ovidiu Gordan2, Zoran Mazej3, Dietrich R. T. Zahn2, Thomas Seyller1, and Martina Wanke1 — 1Technische Physik, TU Chemnitz, Reichenhainer Str. 70, D-09126 Chemnitz, Germany — 2Halbleiterphysik, TU Chemnitz, Reichenhainer Str. 70, D-09126 Chemnitz, Germany — 3Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
Graphene is characterized by two linear bands crossing each other at the K-point of the hexagonal Brillouin zone. In neutral graphene, the Fermi level lies exactly at the crossing point where the density of states is zero. For certain applications, it is desirable to choose both charge carrier type and density which can be accomplished by electrostatic gating or doping. While substitutional doping alters the graphene lattice, charge transfer doping using adsorbates keeps the lattice intact.
In this work, we investigate charge transfer doping of graphene on 6H-SiC(0001) by organic molecules. Angle-resolved photoelectron spectroscopy (ARPES) was used to determine the position of the Dirac point and thus charge carrier type and density. It was observed that fluorinated fullerenes, mainly C60F48 can effectively induce p-type doping [1]. Thereby, the charge transfer is influenced by electron affinity of the adsorbed molecule and by the work function of the graphene, which was investigated in these studies. A model for the doping efficiency [1] of the various adsorbates was tested.
[1] Tadich, et al., APL 102, 241601 (2013)