Phonon transport across Si/Ge interfaces with amorphous interlayers: Elastic–inelastic phonon competition

Abstract

Interfacial thermal resistance due to vibrational mismatch remains a key challenge in thermal management. While crystalline interlayers are known to enhance thermal conductance, the potential of amorphous interlayers remains underexplored. Using non-equilibrium molecular dynamics simulations, we examine how mass distribution in amorphous interlayers affects interfacial thermal conductance (ITC) between Si and Ge. Compared to crystalline interlayers, amorphous ones generally show lower ITC, except under strong vibrational mismatch (e.g., 5 amu mass). This enhanced performance is attributed to the increased phonon density of states overlap and the broadened interfacial mode spectrum induced by amorphous disorder, which collectively facilitate both elastic and inelastic phonon transport. Notably, ITC peaks at 10 amu and exhibits a plateau over a range of masses—distinct from the sharp peaks of crystalline systems. Such plateau behavior can be attributed to a competing interplay between increased elastic contributions and suppressed inelastic transport as the interlayer mass increases. Our findings offer guidance for optimizing ITC in amorphous semiconductor interfaces.