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Center for Nonlinear Studies |
Existing models of phonon transport at solid/solid interfaces are accurate at very low temperatures, but at room temperature and above, they predict values of interfacial thermal conductance that can differ from experiments by an order of magnitude or more. An improved understanding of conductance is important for the design of modern electronic devices with features on scales of tens of nanometers, in which interfacial resistances can be as important as bulk resistances. I present the results of molecular dynamics simulations of thermal transport between solids, with a particular focus on the anharmonicity of atomic forces that is thought to be important at high temperature. The results reinforce the notion that thermal conductance at high temperature is driven by energy exchange among vibrational modes of different frequency (i.e., "inelastic phonon scattering"). However, the results suggest that inelastic scattering at the interface itself contributes surprisingly little to the total conductance at high temperatures. Rather, the conductance is driven by inelastic scattering in the bulk materials. The findings suggest that, in engineering the thermal transport at high-quality interfaces, the anharmonicity of the adjacent materials plays a more important role than previously realized, especially at the operating temperatures of typical devices.
Host: Charlie Scarlett