Carbon Nanotubes as Nanoelectromechanical Systems

TL;DR

This paper theoretically investigates how charging effects influence the electrical and mechanical behavior of suspended carbon nanotubes, revealing discrete position changes, curvature in Coulomb diamonds, bistability, and mode modifications.

Contribution

It introduces a model accounting for capacitance dependence on tube position, predicting discrete steps, bistability, and mode changes in nanotube nanoelectromechanical systems.

Findings

Tube position changes discretely with electron tunneling

Edges of Coulomb diamonds show curvature

Electron tunneling modifies nanotube eigenmodes

Abstract

We theoretically study the interplay between electrical and mechanical properties of suspended, doubly clamped carbon nanotubes in which charging effects dominate. In this geometry, the capacitance between the nanotube and the gate(s) depends on the distance between them. This dependence modifies the usual Coulomb models and we show that it needs to be incorporated to capture the physics of the problem correctly. We find that the tube position changes in discrete steps every time an electron tunnels onto it. Edges of Coulomb diamonds acquire a (small) curvature. We also show that bistability in the tube position occurs and that tunneling of an electron onto the tube drastically modifies the quantized eigenmodes of the tube. Experimental verification of these predictions is possible in suspended tubes of sub-micron length.