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 (63√×63√)−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.
- silicon carbide
- x-ray standing wave
Sforzini, J., Nemec, L., Denig, T., Stadtmüller, B., Lee, T-L., Kumpf, C., Soubatch, S., Starke, U., Rinke, P., Blum, V., Bocquet, F. C., & Tautz, F. S. (2015). Approaching Truly Freestanding Graphene: The Structure of Hydrogen-Intercalated Graphene on 6H-SiC(0001). Physical Review Letters, 114(10), 1-6. . https://doi.org/10.1103/PhysRevLett.114.106804