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HL: Fachverband Halbleiterphysik

HL 15: C/diamond I

HL 15.8: Vortrag

Dienstag, 24. März 2009, 11:15–11:30, POT 51

Adsorbates on graphene: Impurity states and electron scattering — •Tim Wehling¹, Mikhail Katsnelson², and Alexander Lichtenstein¹ — ¹I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstrasse 9, 20355 Hamburg — ²Institute for Molecules and Materials, Radboud University of Nijmegen, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands

Sources of electron scattering in graphene are being controversially debated to date. Midgap states and / or charged impurites are considered as possible factors determining graphene’s electronic transport properties. We present ab-initio studies of impurites on graphene and elucidate the role of the SiO₂ substrate. We show that water and ethanol adsorbates strongly affect the coupling of graphene’s electrons to impurity bands in the substrate. Covalently and ionically bond impurities on free standing graphene are considered and characteristic desorption energies are discussed. Covalently bond impurities are shown to cause midgap states which are strongly coupled to the graphene bands.