Ballistic transport and electrostatics in metallic carbon nanotubes

TL;DR

This paper models ballistic transport and electrostatics in metallic carbon nanotubes, revealing voltage distribution, electric field scaling, and conductance behavior at room temperature, with implications for nanoscale electronic devices.

Contribution

It provides a self-consistent calculation of current and potential drops in metallic nanotubes, highlighting voltage distribution and conductance mechanisms not previously detailed.

Findings

Approximately 10% of voltage drops in the bulk of the nanotube.

Electric field at the center scales faster than 1/L with length.

Room temperature conductance exceeds 4e^2/h due to non crossing subbands.

Abstract

We calculate the current and electrostatic potential drop in metallic carbon nanotube wires self-consistently, by solving the Green's function and electrostatics equations in the ballistic case. About one tenth of the applied voltage drops across the bulk of a nanowire, independent of the lengths considered here. The remaining nine tenths of the bias drops near the contacts, thereby creating a non linear potential drop. The scaling of the electric field at the center of the nanotube with length (L) is faster than 1/L (roughly $1/L^{1.25-1.75}$). At room temperature, the low bias conductance of large diameter nanotubes is larger than $4e^2/h$ due to occupation of non crossing subbands. The physics of conductance evolution with bias due to the transmission Zener tunneling in non crossing subbands is discussed.