First-principles super-cell calculations of cubic inclusions in 6H-SiC were performed. The cubic inclusions could be created in perfect 6H-SiC by the propagation of successive partial dislocations having the same Burgers vector on neighboring basal planes, i.e., multiple stacking faults. The electronic structures and the total energies of 6H-SiC were studied in single crystals that contained 1, 2, 3 or 4 stacking faults, based upon density functional theory in the local density approximation. The total energy calculations revealed that the second stacking-fault energy in 6H-SiC was some 6 to 7 times larger than that of an isolated stacking fault. This was contrary to the trend recently observed in 4H-SiC. The effects of spontaneous polarization upon the electronic properties of stacking disorder were examined in detail. The calculated positions of the quantum well-like localized bands and stacking-fault energies of 3C inclusions in 6H-SiC were compared with those previously determined in 4H-SiC. The possibility of local hexagonal-to-cubic polytypic transformations was considered in the light of the formation energy and quantum-well action.

Ab Initio Study of 3C Inclusions and Stacking-Fault Stacking-Fault Interactions in 6H-SiC. H.P.Iwata, U.Lindefelt, S.Öberg, P.R.Briddon: Journal of Applied Physics, 2003, 94[8], 4972-9