Exceptionally Strong Phonon Scattering by B Substitution in Cubic SiC.

We use ab initio calculations to predict the thermal conductivity of cubic SiC with different types of defects. An excellent quantitative agreement with previous experimental measurements is found. The results unveil that B_{C} substitution has a much stronger effect than any of the other defect types in 3C-SiC, including vacancies. This finding contradicts the prediction of the classical mass-difference model of impurity scattering, according to which the effects of B_{C} and N_{C} would be similar and much smaller than that of the C vacancy. The strikingly different behavior of the B_{C} defect arises from a unique pattern of resonant phonon scattering caused by the broken structural symmetry around the B impurity.