First-principles results for the energetics of several SiC surfaces having different underlying bulk polytypes were used to investigate the role of surface effects in the mechanisms of stacking inversion in SiC. The Si adatom √3 x √3 reconstruction for the cubic SiC (111) and the hexagonal SiC (0001) surfaces was considered, taking into account the different sub-surface bulk terminations which were compatible with the 4H and 6H polytypes, and allowing for 2 opposite stacking orientations of the upper-most surface layer. The investigation revealed that the energy differences among SiC polytypes were enhanced at the surface with respect to the bulk, and that 2-dimensional effects favored the formation of cubic SiC.

Surface-Induced Stacking Transition at SiC (0001). M.C.Righi, C.A.Pignedoli, G.Borghi, R.Di Felice, C.M.Bertoni, A.Catellani: Physical Review B, 2002, 66[4], 045320 (7pp)