Thermal transport by phonons and electrons in aluminum, silver, and gold from first principles

Mode-dependent phonon and electron transport properties in Al, Ag, and Au are predicted using density functional theory and lattice dynamics calculations. The predicted thermal conductivities, electrical conductivities, electron-phonon coupling coefficients, and electron-phonon mass enhancement parameters are in agreement with experimental measurements. At a temperature of 100 K, the phonon contribution to the total thermal conductivity of Al is 5% in bulk and increases to 15% for a 50 nm thick film. In all three metals, phonons with mean free paths between 1 and 10 nm are the dominate contributors to the thermal conductivity at a temperature of 300 K, while the relevant electron mean free paths are 10-100 nm. Despite similar atomic masses, the phonon thermal conductivity of Al is an order of magnitude smaller than that of silicon due to a larger three-phonon phase space and stronger anharmonicity. These results will impact the interpretation of thermoreflectance experiments that can resolve carrier-level contributions to thermal conductivity.