Indirect measurement of the carbon adatom migration barrier on graphene

Although surface diffusion is critical for many physical and chemical\nprocesses, including the epitaxial growth of crystals and heterogeneous\ncatalysis, it is particularly challenging to directly study. Here, we estimate\nthe carbon adatom migration barrier on freestanding monolayer graphene by\nquantifying its temperature-dependent electron knock-on damage. Due to the fast\nhealing of vacancies by diffusing adatoms, the damage rate decreases with\nincreasing temperature. By analyzing the observed damage rates at 300-1073 K\nusing a model describing our finite scanning probe, we find a barrier of (0.33\n\\pm 0.03) eV.\n