Approaching Truly Freestanding Graphene: The Structure of Hydrogen-Intercalated Graphene on6H−SiC(0001)

We measure the adsorption height of hydrogen-intercalated quasifreestanding monolayer graphene on the (0001) face of 6⁢H silicon carbide by the normal incidence x-ray standing wave technique. A density functional calculation for the full (6⁢v3×6⁢v3)−R⁢30° 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 6⁢H−SiC⁡(0001) approaches ideal graphene.     «

We measure the adsorption height of hydrogen-intercalated quasifreestanding monolayer graphene on the (0001) face of 6⁢H silicon carbide by the normal incidence x-ray standing wave technique. A density functional calculation for the full (6⁢v3×6⁢v3)−R⁢30° 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 densit...     »