The difference in film thickness could be explained by a hampered growth process on the Cface. From our work on epitaxial growth of hexagonal and rhombohedral boron nitride (h-BN and r-BN) by CVD using TEB where we also observe similarly shaped pyramid structures, we have noted that the epitaxial growth is hampered by surface poisoning from carbon species. The r-B4C and r-BN both grow epitaxially in the out-of-plane [0001] direction on SiC (0001), and both are expected to be terminated by B atoms. We therefore use Raman spectroscopy (Fig.