Electric Field-Dependent Charge-Carrier Velocity in Semiconducting Carbon Nanotubes

TL;DR

This paper investigates charge transport in semiconducting carbon nanotubes at high bias, revealing that velocity saturation best explains the observed high-current behavior, with implications for nanotube electronic devices.

Contribution

It introduces a velocity saturation model to explain high-bias charge transport in semiconducting nanotubes, advancing understanding beyond previous models.

Findings

Velocity saturation occurs with a saturation velocity of 2 x 10^7 cm/s.

High-bias currents significantly exceed previous limits in metallic SWNTs.

The velocity saturation model best fits the experimental data.

Abstract

Charge transport in semiconducting single-walled nanotubes (SWNTs) with Schottky-barrier contacts has been studied at high bias. We observe nearly symmetric ambipolar transport with electron and hole currents significantly exceeding 25 micron-ampere, the reported current limit in metallic SWNTs due to optical phonon emission. Four simple models for the field-dependent velocity (ballistic, current saturation, velocity saturation, and constant mobility) are studied in the unipolar regime; the high-bias behavior is best explained by a velocity saturation model with a saturation velocity of 2 x 10^7 cm/s.