Electronic and doping properties of hexagonal silicon carbide with stacking faults induced cubic inclusions

Abstract

Silicon carbide (SiC) has been considered one of the most important wide bandgap semiconductors for both scientific interest and technological applications. The existence of stacking faults induced inclusions, originated from the “wrong” stacking sequences of Si-C bilayers, is a general feature in SiC. Until now, however, a systematical understanding of the role of cubic inclusions (CIs) in the electronic and doping properties of hexagonal SiC is still lacking, which may prevent further improvement of its electronic performance. In this article, using advanced first-principles calculations, we have systematically studied the stability, electronic structures, and doping properties of hexagonal SiC with CIs. First, we find that the CIs in SiC have rather low formation energies but high kinetic stability. Second, we find that the electronic structures of SiC can be dramatically tuned by the ratio of CIs in SiC. Third, we demonstrate that the CI-induced band offset and the dipole-discontinuity-induced dipole field in the system can give rise to different ground-state doping sites for dopants at their different charge-states, which can consequently result in novel doping-site-dependent charge-state transition levels (CTLs). Meanwhile, the intrinsic dipole field can dramatically enhance the structural relaxation effects during the ionization of the dopants, which can push the CTLs deeper inside the bandgap compared to the case without CIs. Our findings suggest that CIs could play unusual roles in determining the overall electronic and doping properties of SiC and other similar semiconductors.