Temperature and Doping Dependence of Carbon Interstitial Diffusion in 4H‐SiC from First Principles

The diffusion of carbon interstitial (C i ) mediates the transport of excess carbon atoms and the subsequent interstitial‐vacancy recombination that eliminates the main carrier lifetime killers, carbon vacancies, in silicon carbide (SiC). Therefore, it plays a crucial role in material growth, device fabrication, and thermal treatment for improved material performance. In this work, the thermodynamic and kinetic behaviors of C i diffusion in 4H‐SiC are investigated using first‐principles calculations. The calculations indicate that near the charge‐state transition levels, a migration mechanism emerges in which the charge‐state transition occurs prior to C i migration, which lowers the overall energy barrier. Furthermore, the thermodynamically activated temperature region and kinetic diffusion coefficient are predicted from a theoretical perspective, considering effective potential barriers and entropic effects. Both the activation temperature and diffusion coefficient exhibit strong dependence on the Fermi level and lattice site. Compared to the C i at the k site, the C i at the h site exhibits higher diffusivity. Moreover, slight n‐type doping enhances the diffusion of C i at both sites. Overall, the broader annealing window and higher dynamic diffusion coefficients highlight the significant role of C i in defect healing, offering theoretical insights and essential parameters for optimizing experimental conditions.