Deformation Potential Carrier-Phonon Scattering in Semiconducting Carbon Nanotube Transistors

TL;DR

This paper presents theoretical calculations of carrier transport in semiconducting carbon nanotubes, matching experimental data to determine key scattering parameters and analyzing how subband interactions affect device conductance and mean free path.

Contribution

It introduces a deformation potential coupling constant for semiconducting carbon nanotubes and models intersubband scattering effects on transport properties.

Findings

Deformation potential coupling constant of 14 eV determined.

Theoretical predictions closely match experimental mobility and conductance.

Mean free path increases significantly when the device turns on, depending on diameter and temperature.

Abstract

Theoretical calculations of carrier transport in single-walled carbon nanotubes are compared with recent experiments. Carrier-phonon scattering is accounted for using the deformation potential approximation. Comparing with experiments, a deformation potential coupling constant of 14eV is determined for semiconducting carbon nanotubes. Theory is shown to closely predict the low-field mobility, on conductance, and on resistance of field-effect transistors as a function of induced nanotube charge density, diameter, and temperature. Results indicate that the device conductance is reduced as multiple subband channels conduct due to strong intersubband scattering. Comparison with experiment allows identification of the mean free path (Lm) in semiconducting carbon nanotubes. As the device turns on, Lm is found to increase significantly. When the device is in the on state, the mean free path (Lm-ON) varies linearly with tube diameter and inversely with temperature. Intersubband scattering is found to strongly decrease Lm-ON when a few subbands are occupied. When 3 subband channels are considered at room temperature, Lm-ON decreases from 570nm to 200nm for a 4nm diameter tube when intersubband scattering is included. Since the subband spacing increases with decreasing tube diameter, the effects of intersubband are reduced for smaller diameters.