  Electron-phonon interaction has been well known to create major resistance to
electron transport in metals and semiconductors, whereas less studies were
directed to its effect on the phonon transport, especially in semiconductors.
We calculate the phonon lifetimes due to scattering with electrons (or holes),
combine them with the intrinsic lifetimes due to the anharmonic phonon-phonon
interaction, all from first-principles, and evaluate the effect of the
electron-phonon interaction on the lattice thermal conductivity of silicon.
Unexpectedly, we find a significant reduction of the lattice thermal
conductivity at room temperature as the carrier concentration goes above 1e19
cm-3 (the reduction reaches up to 45% in p-type silicon at around 1e21 cm-3), a
range of great technological relevance to thermoelectric materials.
