Few-hundred GHz Carbon Nanotube NEMS

TL;DR

This paper investigates high-frequency vibrational modes in suspended single-wall carbon nanotube quantum dots, demonstrating tunable bending frequencies up to 280 GHz and high quality factors around one million using low-temperature electron transport.

Contribution

It reports the first measurement of fundamental bending frequencies in nanotube NEMS reaching hundreds of GHz and demonstrates frequency tuning via electrostatic tension.

Findings

Bending frequencies range from 75 to 280 GHz.

Quality factors are approximately 10^6.

Frequencies can be tuned by a factor of two through tension.

Abstract

We study 23 to 30 nm long suspended single-wall carbon nanotube quantum dots and observe both their stretching and bending vibrational modes. We use low-temperature DC electron transport to excite and measure the tubes' bending mode by making use of a positive feedback mechanism between their vibrations and the tunneling electrons. In these nano-electro-mechanical-systems (NEMS), we measure fundamental bending frequencies $f_{bend}\approx$ 75 - 280 GHz, and extract quality factors $Q \sim 10^{6}$. The NEMS' frequencies can be tuned by a factor of two with tension induced by mechanical breakjunctions actuated by an electrostatic force, or tension from bent suspended electrodes.