Structural properties of the multilayer graphene/4H-SiC(000(1) overbar) system as determined by surface x-ray diffraction

We present a structural analysis of the multilayer graphene/4HSiC(0001) system using surface x-ray reflectivity. We show that graphene films grown on the C-terminated (0001) surface have a graphene-substrate bond length that is very short (1.62 angstrom). The measured distance rules out a weak van der Waals interaction to the substrate and instead indicates a strong bond between the first graphene layer and the bulk as predicted by ab initio calculations. The measurements also indicate that multilayer graphene grows in a near turbostratic mode on this surface. This result may explain the lack of a broken graphene symmetry inferred from conduction measurements on this system [C. Berger et al., Science 312, 1191 (2006)].