ABSTRACT
In this paper, we have analyzed mechanical resonances in carbon nanotubes (CNTs) based on single, vertically-oriented tubes for their potential application in high-frequency, high-Q, miniaturized resonators. The nano-electro-mechanical (NEM) resonators were modeled using a commercially available finite-element-simulator, where the electro-mechanical coupling of the CNT to an incoming AC signal on a probe in close proximity was examined. The modeling results confirmed that the mechanical resonance was maximized when the frequency of the input signal was equal to the first order harmonic of the CNT. An investigation of the resonance frequency was also performed for various geometrical parameters of our unique three-dimensional (3D) NEMS architecture. Finally, in-situ observations of mechanical resonance in single, vertically oriented tubes is also reported, where such measurements were conducted inside a scanning-electron-microscope. This work suggests that our vertically oriented tubes are potentially well-suited for resonator applications, such as filter banks in communication systems or for mass sensing applications.
ABSTRACT
We describe the fabrication and characterization of a nanoelectromechanical (NEM) switch based on carbon nanotubes. Our NEM structure consists of single-walled nanotubes (SWNTs) suspended over shallow trenches in a SiO(2) layer, with a Nb pull electrode beneath. The nanotube growth is done on-chip using a patterned Fe catalyst and a methane chemical vapor deposition (CVD) process at 850 degrees C. Electrical measurements of these devices show well-defined ON and OFF states as a dc bias up to a few volts is applied between the CNT and the Nb pull electrode. The CNT switches were measured to have speeds that are 3 orders of magnitude higher than MEMS-based electrostatically driven switches, with switching times down to a few nanoseconds, while at the same time requiring pull voltages less than 5 V.
