Unveiling phonon frequency-dependent mechanism of heat transport across stacking fault in silicon carbide

Abstract

Stacking faults (SFs) are often present in silicon carbide (SiC) and affect its thermal and heat-transport properties. However, it is unclear how SFs influence thermal transport. Using non-equilibrium molecular dynamics and lattice dynamics simulations, we studied phonon transport in SiC materials with an SF. Compared to perfect SiC materials, the SF can reduce thermal conductivity. This is caused by the additional interface thermal resistance (ITR) of SF, which is difficult to capture by the previous phenomenological models. By analyzing the spectral heat flux, we find that SF reduces the contribution of low-frequency (7.5 THz–12 THz) phonons to the heat flux, which can be attributed to SF reducing the phonon lifetime and group velocity, especially in the low-frequency range. The SF hinders phonon transport and results in an effective interface thermal resistance around the SF. Our results provide insight into the microscopic mechanism of the effect of defects on heat transport and have guiding significance for the regulation of the thermal conductivity of materials.