Formation Kinetics and Charge Localization of Spin Defects in the Hexagonal Silicon Carbide

Silicon carbide (SiC) is a wide bandgap semiconductor being used for power electronics, integrated photonics, and quantum information science. Neutral divacancies (VV) in SiC are promising platforms for creating solid-state spin qubits due to their long spin coherence times at room temperature, yet their formation mechanisms remain unclear. Here, we uncover the energy landscape, kinetics, and charge behavior of VV formation in 4H-SiC, a common polytype using density functional theory (DFT) calculations and kinetic Monte Carlo simulations. We find that the activation barrier for VV formation is influenced by the local coordination environment of the anisotropic hexagonal structure. We also show that the electrons localize around silicon vacancies during VV dissociation, resulting in oppositely charged monovacancies. We also explore the non-equilibrium dynamics of point defects in SiC using a kinetic Monte Carlo to understand how VVs are formed during high-temperature thermal annealing. These results offer insights for the selective synthesis of VVs in quantum device engineering.