Mini - symposium B 10 Thermal Transport in Nanoscale

First we will demonstrate that with a proper account of the various aspects of the finite size effects the values of the interfacial thermal (Kapitza) resistance, RK, obtained via molecular dynamics simulations by equilibrium and non-equilibrium methods are the same. In the next part of the presentation we demonstrate that RK between a substrate and a nanoscopic film is thickness-dependent due to combined effect of internal and surface phonon scattering. In particular, when the phonon mean free path is larger than the film thickness and the film surface is atomistically smooth, phonons transmitted from the substrate can travel ballistically in the thin film, be scattered specularly at the surface, and return to the substrate without energy transfer. If the thin film surface scatters phonons diffusely, which is characteristic of rough surfaces, RK is independent of film thickness and is equal to RK that characterizes smooth surfaces in the limit of large film thickness. Our result is useful in calculation of the RK of isolated interfaces. With very rough external surfaces, the size effect on RK can be essentially eliminated and a good estimation of RK of an isolated interface can be obtained with system sizes much smaller than the phonon mean free path.