Anisotropic growth mechanism of epitaxial graphene on 4H-SiC

Abstract

The growth process of SiC epitaxial graphene at low pressure has been investigated systematically. Transition from buffer layer to full monolayer graphene undergoes several stages including graphene nanoribbon nucleation, directional growth and full merging. The morphologies and structures of the graphene at different stages are characterized by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The anisotropic growth mechanism of epitaxial graphene has been revealed by statistical analysis of the shapes and sizes of graphene nanoribbons (width ranges from 40 to 300 nm with a maximum length L_⊥ of ∼ 1.08 μm). It is found that silicon sublimation rate plays a critical role in determining the anisotropic growth of nanoribbons, which is further confirmed by the evolution of the characterized sizes of nanoribbons at different growth stages.