Ab initio study of neutral point defect properties in 6H-SiC based on the SCAN functional

First-principles calculations with the advanced SCAN functional were carried out to investigate the defect formation energies and migration barriers of specific neutral point defects in 6H-SiC including monovacancy, antisite, and self-interstitial defects, as well as the lattice swelling effect caused by them. Our calculation results show that the CSi antisite is the easiest formed point defect in the C-rich environment and the SiC antisite has the lowest formation energy in the Si-rich environment, while the ISi interstitial is the most difficult to be generated in both cases compared with other point defects. In addition, the VC monovacancy and the CSi antisite will cause the lattice shrinkage, while the VSi monovacancy, the SiC antisite, the IC and the ISi interstitials will induce the lattice swelling. Furthermore, the minimum migration barrier among these defects is about 0.97 eV for the IC interstitial, while the migration barrier of the ISi interstitials is about 1.7 eV and the migration barriers of other defects are greater than 3 eV, which indicates that the diffusion of C interstitials plays a major role in the recovery process of defective 6H-SiC crystals. Overall, our work provides systematic insights into the formation and recovery mechanisms of various point defects in 6H-SiC.