Atomic Carbon Transport between the Rh Surface and Bulk in Graphene Formation and Destruction

Abstract

The equilibrium transport of atomic carbon between the Rh surface and bulk, which controls the kinetics of the phase transition resulting in graphene growth or destruction, is investigated. The difference between the activation energy Es1 of atomic-carbon dissolution and the energy E1s of its segregation from the bulk to the surface is found to be ΔE = 0.7 eV. The temperature dependence of the critical coating Neq = Neq(T) in the chemisorbed carbon layer is measured. It is a 2D phase transition that takes place at this coating, and graphene islands start to grow: for example, Neq = 7.7 × 1014 cm–2 at T = 1800 K, and Neq = 3.1 × 1014 cm–2 at T = 1000 K.