Formation of Graphene on SiC( 0001 ) Surfaces in Disilane and Neon Environments
The formation of graphene on the SiC(000) surface (the C-face of the {0001} surfaces) has been studied, utilizing both disilane and neon environments. In both cases, the interface between the graphene and the SiC is found to be different than for graphene formation in vacuum. A complex low-energy electron diffraction pattern with √43 × √43-R ± 7.6° symmetry is found to form at the interface. An interface layer consisting essentially of graphene is observed, and it is argued that the manner in which this layer covalently bonds to the underlying SiC produces the √43 × √43-R ± 7.6° structure [i.e., analogous to the 6√3 × 6√3-R30° “buffer layer” that forms on the SiC(0001) surface (the Si-face)]. Oxidation of the surface is found to modify (eliminate) the √43 × √43-R ± 7.6° structure, which is interpreted in the same manner as the known “decoupling” that occurs for the Si-face buffer layer.