Effect of thin film confined between two dissimilar solids on interfacial thermal resistance.

A non-equilibrium molecular dynamics model is developed to investigate how a thin film confined between two dissimilar solids affects the thermal transport across the material interface. For two highly dissimilar (phonon frequency mismatched) solids, it is found that the insertion of a thin film between them can greatly enhance thermal transport across the material interface by a factor of 2.3 if the thin film has one of the following characteristics: (1) a multi-atom-thick thin film of which the phonon density of states (DOS) bridges the two different phonon DOSs for the solid on each side of the thin film; (2) a single-atom-thick film which is weakly bonded to the solid on both sides of the thin film. The enhanced thermal transport in the single-atom-thick film case is found mainly due to the increased inelastic scattering of phonons by the atoms in the film. However, for solid-solid interfaces with a relatively small difference in the phonon DOS, it is found that the insertion of a thin film may decrease the thermal transport.