J. Sforzini, L. Nemec, T. Denig, Benjamin Stadtmüller, T.-L. Lee, C. Kumpf, S. Soubatch, U. Starke, P. Rinke, V. Blum, F. C. Bocquet, F. S. Tautz
- We measure the adsorption height of hydrogen-intercalated quasifreestanding monolayer graphene on the (0001) face of 6H silicon carbide by the normal incidence x-ray standing wave technique. A density functional calculation for the full (6√3×6√3)−R30° unit cell, based on a van der Waals corrected exchange correlation functional, finds a purely physisorptive adsorption height in excellent agreement with experiments, a very low buckling of the graphene layer, a very homogeneous electron density at the interface, and the lowest known adsorption energy per atom for graphene on any substrate. A structural comparison to other graphenes suggests that hydrogen-intercalated graphene on 6H−SiC(0001) approaches ideal graphene.
