First‐Principles Investigation of Surface‐Induced Effects on the Properties of Divacancy Qubits in 3C‐SiC

Neutral silicon‐carbon divacancies (V Si ) in cubic silicon carbide (3C‐SiC) are promising point defects for quantum technologies based on active crystalline centers. Within the theoretical framework of spin‐polarized density functional theory, this study examines the structural and electronic characteristics of V Si centers near a hydrogen‐terminated 3C‐SiC(001) surface. A (2 × 1): H reconstructed slab of 628 atoms represents the near‐surface environment, with divacancies located at depths ranging from 0.6 to 1.2 nm in basal and axial orientations. The optimized geometries show localized relaxations, and the electronic structure reveals in‐gap defect levels in both spin channels. Furthermore, examination of the zero‐field splitting tensor demonstrates sensitivity to the orientation of the spin defects and their distance from the surface. The findings of this investigation suggest that surface proximity exerts a substantial influence on the spin Hamiltonian of divacancies, providing insight for the engineering of SiC‐based qubits and nanoscale quantum devices.