Origin of the unidentified color centers in 4H -SiC from first principles

As divacancy (VV) and nitrogen-vacancy (NV) color centers in 4H-SiC have attracted significant interest for their potential in quantum technologies, the origins of the photoluminescence (PL) signals (such as PL5-PL8) observed near the VVs signals (PL1-PL4) remain a mystery. In this paper, multiple defect clusters are designed by combining VVs with intrinsic defects and the common extrinsic elements including oxygen, nitrogen, and hydrogen. Based on the first-principles calculations of the spin configuration, formation energy, zero-phonon line, and zero-field splitting, two configurations of OV0 (one oxygen atom filling the carbon vacancy in VV0) are attributed for PL5 and PL6, and one configuration of NHV0 (one hydrogen atom attached to the nitrogen atom in NV0) is the source of PL8. Further radiative lifetime calculations confirm that these defect clusters are good single-photon sources. Additionally, we found that the OHV+ (OV with one hydrogen atom bonded with the oxygen atom at +1 charge state) are potential color centers with S = 1. In this paper, we provide theoretical insights not only into the preparation of color centers such as PL5, PL6, and PL8 but also into developing color centers that are related to VVs.