Substrate induced bandgap in multilayer epitaxial graphene on the 4H-SiC (000(1)over-bar) surface

We have investigated the electronic structures of graphene layers epitaxially grown on the 4H-SiC (000 (1) over bar) surface up to six layers by using first-principles methods. The graphene layers grown on an ideal SiC interface are found to be p doped, whereas, those grown on a C-deficient SiC interface are found to be n doped. We discuss the interlayer screening effects from the positions of the Fermi levels of each layer in our simulation. Interestingly, we find that the substrate may induce small atomic distortions in the graphene layers which could open about a 10 meV band gap in each graphene layer. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim