| AVS 59th Annual International Symposium and Exhibition | |
| MEMS and NEMS | Monday Sessions |
| Session MN+AS-MoM |
| Session: | Characterization of Surfaces and Interfaces in MEMS and NEMS |
| Presenter: | M.R. Kan, University of Alberta, Canada |
| Authors: | M.R. Kan, University of Alberta, Canada Z. Diao, National Institute for Nanotechnology, NRC Canada V.T.K. Sauer, University of Alberta, Canada M.R. Freeman, University of Alberta, Canada W.K. Hiebert, National Institute for Nanotechnology, NRC Canada |
| Correspondent: | Click to Email |
Nano-electromechanical systems (NEMS)have exciting potential for fields ranging from quantum measurement science to ultrasensitive mass detection. For many of these applications, a key challenge is implementing a fast, reliable, low-noise technique for translating small mechanical motion to electronic signals. Electron tunneling transduction based on quantum tunneling is a promising technique to measure small displacements, because the tunneling current is so sensitive to the change in distance between the probing tip and the sample surface (one angstrom distance change causes 7 times tunneling current change). With frequency downmixing, the bandwidth limitation associated with the large RC time constant in the circuits can be overcome; very high frequencies may become accessible, fundamentally limited only by the tunneling rate IT/e in the GHz range.
Using electron tunneling to sense nanomechanical motion comes with an inherent risk of back-action of the sensing probe (STM tip) on the mechanical device. The local tip-sample energy gradients introduce spring forces that can produce sizable shifts in resonance frequencies and may also affect sample quality factors. Understanding these effects is important for reliable use of downmixed tunneling transduction. Controlling them will allow for novel methods of MEMS and NEMS tuning of both frequency and quality factor.
In this presentation, we will report our observation of back-action forces on MEMS devices during downmixed electron tunneling transduction. We explore differences in the magnitude of the back-action force for different flexural and torsional vibrational modes (with varying degrees of inherent stiffness). We also discuss the perturbation to device quality factors. Finally, the vibration of the back-action force as a function of tip-sample distance is investigated.