Vacancy-mediated enhancement of interfacial thermal transport in Si/SiC heterojunctions: a molecular dynamics study

Abstract

Overcoming the intrinsic phonon mismatch at heterogeneous interfaces is a central challenge in nanoscale thermal management. In this work, we use non-equilibrium molecular dynamics (NEMD) to investigate the Si/SiC interface, uncovering a mechanism whereby strategically placed vacancy defects within the SiC bulk significantly enhance interfacial thermal conductance (ITC) by up to 87%. Our analysis of the phonon density of states (PDOS) demonstrates that this enhancement arises from inelastic phonon scattering in the defective region. High-frequency SiC phonons are effectively down-converted into lower-frequency modes, dramatically increasing the vibrational spectral overlap with Si and opening new, efficient channels for energy transport across the phononic barrier. Therefore, engineering remote defects offers a viable strategy to enhance thermal transport across dissimilar material interfaces without compromising the interface's structural quality, providing clear design guidelines for advanced thermal management solutions.