Anisotropic layer-by-layer growth of graphene on vicinal SiC(0001) surfaces

Abstract

Epitaxial graphene is formed on vicinal SiC(0001) surfaces via high temperature annealing in vacuum. Steps act as a significant ``kicker'' of graphene nucleation to feed C atoms. At elevated temperatures, graphene growth is controlled by the decomposition of Si-C bonds at step edges, Si desorption, and C diffusion on the surface. The limited Si desorption is due to the dependence of the growth rate on the thickness of graphene layers. The fabricated graphene layer(s) acts as a Si-diffusion barrier, which in turn induces local thermal equilibrium between the graphene layer and the SiC surface. C atoms preferentially diffuse along the steps, resulting in anisotropic layer-by-layer growth, which is characteristic in this system.