Interfacial thermal transport between large lattice mismatch materials enhanced by atomic defects*

Control of interfacial thermal transport across complex interfaces is predicated on our ability to identify and (de-)couple contributions associated with low-dimensional interfacial features and structural and compositional inhomogeneities. In this study, we aim to reveal the relationship between interfacial thermal transport and defects, and establish its connection with underlying phonon-interfacial defect scattering mechanisms. We combine classical non-equilibrium molecular dynamics (MD) simulations with normal mode analysis (NMA) to investigate thermal transport across Cu/Si interface as a function of defect concentration in the interfacial region. We find that vacancies have a dramatic effect: interfacial thermal conductance increases by as much as 76% for the surface vacancy concentration of only 3%. NMA decomposition of the spectral phonon heat flux suggests that interfacial defects strongly affect inelastic phonon transmission. Our results establish relationships among the distribution of near interface defects, the extent of intermixing, thermal conductance and phonon scattering.