Interfacial thermal resonance in an SiC-SiC nanogap with various atomic surface terminations.

Quasi-Casimir coupling can induce phonon heat transfer across a sub-nanometer vacuum gap between monoatomic solid walls without electromagnetic fields. However, it remains unclear how the atomic surface terminations in diatomic molecules contribute to phonon transmission across a nanogap. Herein, we study the thermal energy transport across an SiC-SiC nanogap with four pairs of atomic surface terminations using classical nonequilibrium molecular dynamics simulations. In the case of identical atomic surface terminations, the net heat flux and thermal gap conductance are much greater than those in the nonidentical cases. Thermal resonance occurs between identical atomic terminated layers, whereas it vanishes between nonidentical ones. A notable heat transfer enhancement in the identical case of C-C is due to optical phonon transmission, with thermal resonance between the C-terminated layers. Our findings deepen the understanding of phonon heat transfer across a nanogap and provide insights into thermal management in nanoscale SiC power devices.