Probing epitaxial growth of graphene on silicon carbide by metal decoration

Using Co-decoration technique coupled with in situ scanning tunneling microscope (STM), the evolution of epitaxial graphene was found to preferentially begin at step edges of the silicon carbide surface and occurs with loss of Si and breakdown of C-rich $(63×63)R30°$ template, which provides the C source for graphene growth. Interestingly, a new C-rich phase is also formed at the interface and it acts as a buffer layer for graphene from underlying bulk. STM reveals that graphene lies $2.3±0.3Å$ above the buffer layer, larger than $sp3$ C–C bond length $(1.54Å)$ but shorter than graphite interlayer separation $(3.37Å)$⁠, suggesting a pseudo-van der Waals interfacial interaction.