title: Ab initio study of graphene on SiC.
abstract: Employing density-functional calculations we study single and double graphene layers on Si- and C-terminated 1x1-6H-SiC surfaces. We show that, in contrast with earlier assumptions, the first carbon layer is covalently bonded to the substrate and cannot be responsible for the graphene-type electronic spectrum observed experimentally. The characteristic spectrum of freestanding graphene appears with the second carbon layer, which exhibits a weak van der Waals bonding to the underlying structure. For Si-terminated substrate, the interface is metallic, whereas on C face it is semiconducting or semimetallic for single or double graphene coverage, respectively.
authors.affiliation: Theoretische Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstrasse 7, 91058 Erlangen, Germany. Alexander.Mattausch@physik.uni-erlangen.de
authors.forename: Alexander
authors.initials: A
authors.lastname: Mattausch
authors.forename: Oleg
authors.initials: O
authors.lastname: Pankratov