Exploring High-Spin Color Centers in Wide Band Gap Semiconductors SiC: A Comprehensive Magnetic Resonance Investigation (EPR and ENDOR Analysis)

The proposed method in this study focuses on the systematic characterization of nitrogen–vacancy (NV) centers in wide bandgap silicon carbide (SiC) polytypes, specifically 4H-SiC and 6H-SiC, in order to evaluate their potential as solid-state qubits and quantum sensors. Using high-frequency photoinduced electron paramagnetic resonance (EPR) at 94 GHz, complemented by electron–nuclear double resonance (ENDOR), the spin and optical properties of NV centers were comprehensively investigated. Key spin Hamiltonian parameters were extracted, including a zero-field splitting constant of approximately 1.2–1.3 GHz, hyperfine interaction of ~1.1 MHz with ^14N nuclei, and a quadrupole constant of ~2.45 MHz. Optical polarization efficiency was shown to be polytype-dependent, with 532 nm excitation yielding optimal results in 4H-SiC and 980 nm excitation most effective in 6H-SiC. Relaxation studies revealed T₁ times in the range of hundreds of microseconds and T₂ coherence times of ~25 µs at room temperature, extended to ~60 µs at 150 K under advanced pulse sequences. Observation of Rabi oscillations confirmed coherent spin manipulation, validating the controllability of NV spin states. Furthermore, ENDOR spectra revealed well-resolved electron–nuclear interactions, highlighting the feasibility of nuclear spins as auxiliary qubits in multi-qubit registers.

KEYWORDS: Nitrogen-vacancy centers; Silicon carbide (SiC); Electron paramagnetic resonance (EPR); Electron–nuclear double resonance (ENDOR); Spin coherence; Quantum sensing; Solid-state qubits; Spin–photon interfaces.