First-principles characterization of an AlSiVC center in cubic silicon carbide

Abstract

We performed first-principles calculations combined with group theory analysis to characterize the geometry, formation energy, and electronic structures of an AlSiVC center in cubic silicon carbide (3C-SiC) crystals, a complex defect consisting of a carbon vacancy and an adjacent substitutional aluminum impurity on a silicon site. We found that the AlSiVC center has a stable C3v symmetric geometry, with a formation energy lower than that of either a silicon vacancy (VSi) or a carbon vacancy (VC). The defect levels of an AlSiVC center in 3C-SiC align in a way different from those of a NCVSi center, i.e., the twofold degenerated ex,y level is lower than the singlet levels in energy. These defect levels reside in the conduction bands and thus are unsuitable for qubit operations. The donor features of the AlSiVC center may be responsible for the low hole concentration in Al-doped 3C-SiC.