First-principles study on the stability, electronic structure, and optical properties of neutral phosphorus-related point defects in 4H–SiC

Doping-induced point defects have the capacity to alter physical performances of host semiconductors such as silicon carbide (SiC). Nevertheless, structural and functional characterization of the defects lacks comprehensiveness, which impedes determination of influence from the defects on hosts. In this study, stability, electronic structure, and optical properties of neutral phosphorus (P)-related point defects in 4H–SiC were calculated by first-principles methods. The P dopant tends to form neutral substitutions rather than neutral interstitials. Neutral substitutions and interstitials prefer to appear in the Si sublattice and hexagonal coordination site, respectively. Both neutral substitutions and interstitials lead to a minor reduction in the bandgap width. Meanwhile, neutral interstitials introduce impurity energy levels in the bandgap. Based on the obtained total and projected density of states, neutral substitutions and interstitials contribute to the electronic states of 4H–SiC in different ways. As for optical properties, neutral substitutions and interstitials increase the static dielectric constant and lead to a redshift of the main peaks of the dielectric function and absorption coefficient with diverse influence power. This study gives guidance to experiments for exploring the variations in neutral dopants in 4H–SiC to meet specific applications.