First-principles prediction of spin-triplet qubits in two-dimensional silicon carbide

Two-dimensional silicon carbide (2D-SiC) is a promising host material for quantum bits (qubits) due to its stable structure, wide band gap, and the naturally abundant zero-nuclear-spin isotopes. In this work, first-principles calculations were conducted to investigate defect centers in 2D-SiC resulting from the doping of B, N, O, P, and S nonmetal atoms. Among the 20 defect centers examined, the neutral ${\mathrm{O}}_{\mathrm{C}}{\mathrm{V}}_{\mathrm{Si}}$ and ${\mathrm{S}}_{\mathrm{C}}{\mathrm{V}}_{\mathrm{Si}}$ are identified as particularly promising candidates, displaying spin-triplet ground states, high Debye-Waller (DW) factors of 44.93% and 34.75%, and short radiative lifetimes of 28.546 ns and 109.230 ns, respectively. An analysis of defect formation energies confirms their thermodynamic stabilities. Furthermore, the simulated photoluminescence spectra and hyperfine tensors provide a theoretical foundation for the experimental identification of ${\mathrm{O}}_{\mathrm{C}}{\mathrm{V}}_{\mathrm{Si}}$ and ${\mathrm{S}}_{\mathrm{C}}{\mathrm{V}}_{\mathrm{Si}}$ defects in 2D-SiC.