High-field electrothermal transport in metallic carbon nanotubes

We describe the electrothermal transport in metallic carbon nanotubes (m-CNTs) by a semiclassical approach that takes into account the high-field dynamical interdependence between charge carrier and phonon populations. Our model is based on the self-consistent solution of the Boltzmann transport equation and the heat equation mediated by a phonon rate equation that accounts for the onset of nonequilibrium (optical) phonons in the high-field regime. Given the metallic nature of the nanostructures, a key ingredient of the model is the assumption of local thermalization of charge carriers. Our theory remarkably reproduces the room-temperature electrical characteristics of m-CNTs on substrate and free standing (suspended), shedding light on charge-heat transport in these one-dimensional nanostructures. In particular, the negative differential resistance observed in suspended m-CNTs under electric stress is attributed to inhomogeneous field profile induced by self-heating rather than the presence of hot phonons.