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.