Multiple phonon processes contributing to inelastic scattering during thermal boundary conductance at solid interfaces

A new model is developed that accounts for multiple phonon processes on interface transmission between two solids. By considering conservation of energy and phonon population, the decay of a high energy phonon in one material into several lower energy phonons in another material is modeled assuming diffuse scattering. The individual contributions of each of the higher order inelastic phonon processes to thermal boundary conductance are calculated and compared to the elastic contribution. The overall thermal boundary conductance from elastic and inelastic (three or more phonon processes) scattering is calculated and compared to experimental data on five different interfaces. Improvement in value and trend is observed by taking into account multiple phonon inelastic scattering. Three phonon interfacial processes are predicted to dominate the inelastic contribution to thermal boundary conductance.