Multiscale simulation in vanadium-doped 4H-SiC: a defect-carrier–phonon synergy

Abstract Vanadium doping effectively modulates carrier transport and enhances breakdown voltage in 4H-SiC, yet its underlying microscopic mechanisms remain incompletely understood. The lack of clarity regarding doping-induced carrier behavior in both conducting and blocking states impedes rational carrier selection and limits device performance optimization. This study employs a multiscale simulation framework integrating first-principles calculations with Boltzmann transport theory, incorporating electro-thermal coupling effects, to systematically investigate the influence of vanadium doping on the electrical and thermal properties of 4H-SiC. Results demonstrate that vanadium introduces new defect energy levels, enhances carrier–phonon scattering, and significantly lowers carrier mobility, which is identified as the dominant contribution to the improved breakdown voltage. Meanwhile, the doping-induced lattice distortion markedly suppresses phonon transport and reduces thermal conductivity. The combined effect of these competing electrical-thermal processes ultimately strengthens the material’s voltage withstand capability. This work establishes a comprehensive defect-carrier–phonon coupling model, providing critical theoretical guidance for the performance optimization of high-power 4H-SiC devices through defect engineering.