Determination of the adhesion energy of graphene on SiC(0001) via measurement of pleat defects
Pleat defects in graphene grown on SiC(0001) were studied and used to determine the adhesion energy between few-layer graphene (3±1 monolayers) and the substrate. An adhesion energy of 3.0±1.6
1.0 was determined using a continuum model describing the buckling of the film and delamination. The continuum model used can be applied to any graphene-substrate system in which pleat formation occurs due to differences in thermal expansion. The large value of adhesion energy observed for graphene on SiC, compared with that on materials such as Ni, Cu, and SiO2, arises from delamination of the graphene film and buffer layer from the SiC substrate, which requires the breaking of covalent bonds. Preferential orientation of pleats at 120° with respect to each other was also observed; this is attributed to favorable formation of pleats along high symmetry directions of the graphene lattice.