Near-Interface Effects on Interfacial Phonon Transport—Competition Between Phonon-Phonon Interference and Phonon-Phonon Scattering

Recent studies suggest that the phonon-phonon couplings in the near-interface region may affect interfacial thermal transport. In this paper, we revisit the interfacial thermal transport considering phonon-phonon couplings across the interface and in the near-interface region. We find that phonon-phonon couplings in the near-interface region show a dual influence on the interfacial thermal transport. On the one hand, the phonon-phonon couplings in the near-interface region will benefit the interfacial thermal transport via phonon-phonon interference. On the other hand, the phonon-phonon couplings in the near-interface region hinder the interfacial thermal transport through phonon-phonon scatterings. Mechanical-contacted and chemical-bonding Cu/Si interfaces are chosen as examples to investigate interfacial thermal transport. For mechanical-contacted Cu/Si interfaces, the interfacial thermal transport is dominant by the phonon-phonon couplings across the interface. The influence of phonon-phonon couplings in the near-interface region on interfacial thermal transport could be ignored. For chemical-bonding Cu/Si interfaces, phonon-phonon couplings in the near-interface region can contribute as high as 10% (7% with quantum corrections) to interfacial thermal transport at low temperatures (i.e., < 300 K). This is because the interference among these phonons in the near-interface region is stronger than their corresponding scatterings. At high temperatures (i.e., > 300 K), the phonon-phonon scatterings in the near-interface region become more important and surpass the corresponding interference. Consequently, the phonon-phonon couplings in the near-interface region will hinder interfacial thermal transport. Our work here quantifies the influence of phonon-phonon couplings in the near-interface region on interfacial thermal transport, which advances the fundamental understanding of interfacial thermal conduction.