First-principles super-cell calculations were carried out in order to investigate clusters of C interstitials in 3C- and 4H-SiC. Based upon the calculated formation energies, the complex formation of C interstitials or their aggregation to C antisites was found to be energetically favored in SiC. The electronic and vibronic properties of the C interstitials and their aggregates depended strongly upon the polytype. Using the calculated hyperfine constants and local vibrational modes of C clusters, the possible relation to known C-related centers was considered.

Aggregation of Carbon Interstitials in Silicon Carbide - a Theoretical Study. A.Gali, P.Deák, P.Ordejón, N.T.Son, E.Janzén, W.J.Choyke: Physical Review B, 2003, 68[12], 125201 (11pp)