Determination of the graphene growth mode on SiC(0001) and SiC(000-1)
  We have determined the growth mode of graphene on SiC(0001) and SiC(000-1) using ultra-thin, isotopically-labeled Si13C `marker layers' grown epitaxially on the Si12C 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 13C is located mainly in the outermost graphene layers, indicating that, during decomposition, new graphene layers form underneath existing ones. 
J.B. Hannon, M. Copel, and R.M. Tromp
cond-mat.mtrl-sci