Shuttle Instability in Self-Assembled Coulomb Blockade Nanostructures

TL;DR

This paper investigates a self-assembled Coulomb-blockade nanostructure that exhibits a shuttle instability, where mechanical vibrations enable charge transfer, resulting in a novel current mechanism and hysteresis effects at room temperature.

Contribution

It introduces a model demonstrating self-excitation of high-frequency vibrations and a shuttle mechanism for charge transfer in Coulomb-blockade nanostructures.

Findings

Periodic grain vibrations can be self-excited at 10-100 GHz.

Shuttle instability causes hysteresis in current-voltage characteristics.

Analytical and Monte Carlo methods confirm the shuttle mechanism.

Abstract

We study a simple model of a self-assembled, room temperature Coulomb-blockade nanostructure containing a metallic nanocrystal or grain connected by soft molecular links to two metallic electrodes. Self-excitation of periodic grain vibrations at 10 - 100 GHz is shown to be possible for a sufficiently large bias voltage leading to a novel `shuttle mechanism' of discrete charge transfer and a current through the nanostructure proportional to the vibration frequency. For the case of weak electromechanical coupling an analytical approach is developed which together with Monte Carlo simulations shows that the shuttle instability for structures with high junction resistances leads to hysteresis in the current - voltage characteristics.