Aggregation of carbon interstitials in silicon carbide: A theoretical study

Ab initio supercell calculations have been carried out to investigate clusters of carbon interstitials in 3C- and 4H-SiC. Based on the calculated formation energies, the complex formation of carbon interstitials or their aggregation to carbon antisites is energetically favored in SiC. The electronic and vibronic properties of the carbon interstitials and their aggregates depends strongly on the polytype. Using the calculated hyperfine constants and local vibrational modes of carbon clusters the possible relation to known carbon-related centers will be discussed.