Abstract
Employing density-functional calculations we study single and double graphene layers on Si- and C-terminated — 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.
- Received 8 January 2007
DOI:https://doi.org/10.1103/PhysRevLett.99.076802
©2007 American Physical Society