  We show that the self-consistent dynamics of both phonons and electrons is
the necessary ingredient for the reliable description of the hot phonons
generation during electron transport in metallic single-wall carbon nanotubes
(SWNTs). We solve the coupled Boltzmann transport equations to determine in a
consistent way the current vs. voltage (IV) curve and the phonon occupation in
metallic SWNTs which are lying on a substrate. We find a good agreement with
measured IV curves and we determine an optical phonon occupation which
corresponds to an effective temperature of several thousands K (hot phonons),
for the voltages typically used in experiments. We show that the high-bias
resistivity strongly depends on the optical phonon thermalization time. This
implies that a drastic improvement of metallic nanotubes performances can be
achieved by increasing the coupling of the optical phonons with a
thermalization source.
