Kinetics of Graphene Formation on Rh(111) Investigated by In Situ Scanning Tunneling Microscopy

In situ scanning tunneling microscopy observations of graphene formation on Rh(111) show that the moiré pattern between the lattices of the overlayer and substrate has a decisive influence on the growth. The process is modulated in the large unit cells of the moiré pattern. We distinguish two steps: the addition of a unit cell that introduces one or more new kinks and the addition of further unit cells that merely advance the position of an existing kink. Kink creation is the rate-limiting step, with kink creation at small-angle, concave corners in the graphene overlayer exhibiting the lower barrier.