We employ hybrid density functional calculations to search for defects in different polytypes of SiC that may serve as qubits for quantum computing. We explore the divacancy in $4H\text{−}$ and $3C\text{−}\mathrm{SiC}$, consisting of a carbon vacancy adjacent to a silicon vacancy, and the nitrogen-vacancy (NV) center in $3C\text{−}\mathrm{SiC}$, in which the substitutional ${\mathrm{N}}_{\mathrm{C}}$ sits next to a Si vacancy (${\mathrm{N}}_{\mathrm{C}}-V_{\mathrm{Si}}$). The calculated excitation and emission energies of the divacancy in $4H\text{−}\mathrm{SiC}$ are in excellent agreement with experimental data, and aid in identifying the four unique configurations of the divacancy with the four distinct zero-phonon lines observed experimentally. For $3C\text{−}\mathrm{SiC}$, we identify the paramagnetic defect that was recently shown to maintain a coherent quantum state up to room temperature as the spin-1 neutral divacancy. Finally, we show that the $({\mathrm{N}}_{\mathrm{C}}-V_{\mathrm{Si}}{)}^{-}$ center in $3C\text{−}\mathrm{SiC}$ is highly promising for quantum information science, and we provide guidance for identifying this defect.

• Received 24 September 2014
• Revised 29 June 2015

DOI:https://doi.org/10.1103/PhysRevB.92.045208