The structures, formation energies and stable configurations of elementary defects (vacancies, antisite defects and self-interstitials) in 3C- and 4H-SiC were studied by using classical molecular dynamics simulation with a recently developed interatomic potential. The defect structures in 3C-SiC were relatively simple, but those in 4H-SiC were more complex. The interstitials between hexagonal and trigonal rings were characteristic for 4H-SiC and other hexagonal polytypes, but not for 3C-SiC. The number of non-equivalent defects in 4H-SiC was much higher than that in 3C-SiC, and a considerable difference was found for some complex and anisotropic defects, in particular for the dumbbells D1Si–Si, D1Si–C and D2Si–C. The lattice deformation beyond the first nearest neighbor shell, which depended strongly upon the polytype structure, played an important role in these effects. However, the polytypism did not have a significant effect upon the structure and energetics of the more compact and isotropic defects, such as vacancies and antisite defects. Despite the complexity of defect configurations, the tetrahedral interstitials had very similar properties in 3C- and 4H-SiC because their first-, second- and third-nearest neighbor shells were identical.

Structures and Energetics of Defects - a Comparative Study of 3C- and 4H-SiC. F.Gao, M.Posselt, V.Belko, Y.Zhang, W.J.Weber: Nuclear Instruments and Methods in Physics Research Section B, 2004, 218, 74-9