An Investigation into the Roughness and Film Thickness Effects on the Interfacial Thermal Resistance

ABSTRACT The roughness and film thickness effects on the interfacial thermal resistance (ITR) are explored at two deliberately selected temperatures in use of Monte-Carlo simulation method. Particular methods are proposed to define properly the phonon emitting temperature based on the one-way deviational heat flux, and to define correctly the phonon equilibrium temperature by considering the different properties and residence times of incident, transmitted, and reflected phonons near an interface. A mixed mismatch model which allows polarization conversion is constructed and employed. The so-obtained traditional ITRs, defined based on the emitting temperature difference, and the revised ITRs, defined based on the equilibrium temperature difference, are compared with model predictions in the literature. Simulation results show that at high temperature the revised ITR decreases monotonically with increasing film thickness and at low temperature it possesses a local minimum against the interface roughness. The latter is explained by the monotonically increasing traditional ITR and monotonically decreasing ratio of the equilibrium temperature difference to emitting temperature difference with increasing roughness. Among all the studied models, only the newly proposed one can well predict the ITR for different interface roughness at low temperature. None of the models captures the monotonic decrease of ITR with film thickness at high temperature however.