The structural and electronic properties of Carbon-related point defects on 4H-SiC (0001) surface

Carbon-related point defects on the 4H-SiC surface are essential for understanding the origin of defects at the SiO2/SiC interface and improving the quality of epitaxial materials. In this work, a first principle calculation was carried out to study the structural and electronic properties of carbon antisite (C-Si), vacancy (V-C) and interstitial defects (C-i1, C-i2, C-i3 and C-i4) on the 4H-SiC (0001) surface. The optimized structures showed that interstitial defects except C-i2 caused the surface reconstruction of 4H-SiC. The variation in formation energies with chemical potentials of the carbon for all defects indicated that the C-rich condition was beneficial to the formation of C-Si, C-i1, C-i3 and C-i4, whereas the Si-rich condition was more favorable to V-C. We also observed that these defects except C-i4 generated the corresponding defect energy levels in the bandgap of 4H-SiC by calculating the density of states and local charge densities. Furthermore, the effects of defect coverage and lateral lattice strain on structural and electronic properties of these defects were provided.