Formation energies, abundances, and the electronic structure of native defects in cubic SiC

Abstract

The relative abundance of native point defects in cubic SiC has been studied via ab initio calculations as a function of composition and the Fermi-level position. For Si-rich cubic SiC, the ${\mathrm{Si}}_{\mathrm{C}}$ antisite is the dominant defect in $n$-type material, while the carbon vacancy, which is a double donor, dominates in $p$-type material. These results explain the experimentally observed low doping efficiencies of acceptors and the strong self-compensation effects in Si-rich cubic SiC. In C-rich SiC, the dominant defect is the electrically inactive ${\mathrm{C}}_{\mathrm{Si}}$ antisite, regardless of the position of the Fermi level. The slightly C-rich cubic SiC is thus a more suitable material for $p$-type doping.