Phonon scattering at a rough interface between two fcc lattices

Elastic phonon scattering at an atomically rough interface that separates two fcc lattice leads is computed via a Green's function method. Results are compared to specular and diffuse phonon scattering models, both of which are widely used in the numerical simulations of phonon Boltzmann transport equations. The shape of the discrete interface in the model is quantified by its spectral characteristics. It is found that the amplitude of the interface height fluctuations has strong influence on the effective interface specularity, while the effect of the two-point correlation length is minor. The average phonon transmission coefficient as well as the overall thermal resistance, however, is relatively insensitive to the interface roughness.