Identification of positively charged carbon antisite-vacancy pairs in 4H-SiC

An antisite-vacancy pair and a monovacancy are a set of fundamental stable and/or metastable defects in compound semiconductors. Theory predicted that carbon antisite-vacancy pairs would be much more stable in p-type SiC than silicon vacancies and that they would be a common defect. However, no experimental evidence has yet supported this prediction. We reexamine electron-irradiated p-type 4H-SiC and identify the positively charged carbon antisite-vacancy pairs (CSiVC+) by means of electron paramagnetic resonance and ab initio calculations. We compare them with other coexisting defects such as carbon vacancy (V-C) and divacancy (VSiVC) and show that CSiVC and V-C are very similar in terms of thermal stability and electronic levels.