Direct measurement of the growth mode of graphene on SiC(0001) and SiC(0001̄)

We have determined the growth mode of graphene on SiC(0001) and SiC(0001̄) using ultrathin, isotopically labeled SiC13 "marker layers" grown epitaxially on the SiC12 surfaces. Few-layer graphene overlayers were formed via thermal decomposition at elevated temperature. For both surface terminations (Si face and C face), we find that the C13 is located mainly in the outermost graphene layers, indicating that, during decomposition, new graphene layers form underneath existing ones. © 2011 American Physical Society.