PHYSICS SEMINAR
Electronics and Mechanics in Ultra-short Carbon Nanotubes
Alexandre Champagne
Concordia University
Thursday, September 13, 2012
4:00 p.m.
Nicolls 314
Abstract
At the nanoscale, electronics and mechanics are strongly coupled and their interactions can be studied in so-called nano-electromechanical-systems (NEMS). Single-wall carbon nanotubes (SWCNTs) are among the most interesting NEMS as they form 1-dimensional crystals without any defect, they are exceptionally strong mechanically, and their electrons can travel long distances without scattering (quantum transport).
We describe a method to fabricate clean suspended SWCNT transistors hosting a single quantum dot ranging in length from a few 10s of nm down to ≈3 nm [1]. We measure electron transport in these devices at low temperature and show that they form clean and tunable single-electron transistors. We also observe both the stretching and bending vibrational modes of the nanotubes via electron spectroscopy. We use 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 NEMS, we measure fundamental bending frequencies fbend ≈ 75−280 GHz and extract quality factors Q ∼ 106 [2]. The NEMS's frequencies can be tuned by a factor of 2 with mechanical tension.
[1] J. O. Island, V. Tayari, S. Yigen, A. C. McRae, and A. R. Champagne, Appl. Phys. Lett., 99, 243106 (2011).
[2] J. O. Island, V. Tayari, A. C. McRae, and A. R. Champagne, Nano Letters, accepted (2012).
This talk is funded by the Speaker's Committee
