The influence of intrinsic point defects on the electronic band structures and swelling behaviors of 4H-SiC

In this work, both the first principles calculations and molecular dynamics simulations are adopted to investigate the formation ability of various intrinsic point defects in 4H-SiC as well as the electronic band structure changes and the swelling effects caused by them. Our results demonstrate that the classical MEAM potential has an unsatisfactory performance on the defect formation energies as compared with the ab initio calculations based on the advanced SCAN functional, but provides a reasonable description on the volumetric swelling caused by single point defect. Both the SCAN and MEAM calculations indicate that the V-C monovacancy and the C-Si antisite defect will cause the lattice shrinkage, while the V-Si monovacancy, the Si(C )antisite, the I-C and the I-Si interstitials will induce the volumetric swelling. Besides that, first principles calculations reveal that monovacancies and interstitials would induce defective electronic states near the Fermi level, while antisites have negligible influence on the electronic band structures as compared with the pristine case. Furthermore, the molecular statics relaxations are employed to explore the influence of point defect densities on the swelling behaviors of 4H-SiC, which reveals that the volume swelling ratios present good linear relationships with the increased density of the V-C monovacancy, C-Si antisite, Si-C antisite and I-C interstitial defects, but express complex non-linear tendencies with the V-Si monovacancy and I-Si interstitial defects. Therefore, our research deepens the understanding of the point defects' effects on the electronic properties and swelling behaviors of 4H-SiC.