A theory for the high-field current-carrying capacity of one-dimensional semiconductors

It is shown that current saturation in semiconducting carbon nanotubes is indistinguishable from metallic nanotubes if the carrier density is above a critical value determined by the bandgap and the optical phonon energy. This feature stems from the higher number of current-carrying states in the semiconducting tubes due to the van Hove singularity at the band edge. Above this critical carrier density, the ensemble saturation velocity at high fields is found to be independent of the bandgap, but strongly dependent on the carrier density, explaining recent observations. The results derived are valid in the limit of ultrafast electron-optical phonon interaction and diffusive transport at high electric fields. The analytical results derived are then applied to one-dimensional 1D semiconducting graphene nanoribbons as well as semiconductor nanowires with parabolic bandgap. A generalized concept of phonon-limited saturation currents in high-field transport in 1D structures emerges from these considerations. © 2009 American Institute of Physics. DOI: 10.1063/1.3147877