Self-assembled switches based on electroactuated multiwalled nanotubes

Abstract

A fabrication process for nanoelectromechanical systems (NEMS) based on multiwalled carbon nanotubes (CNTs) suspended across metallic trenches is described. The process is versatile and allows the production of CNT-NEMS with singly or doubly clamped nanotubes at an adjustable height above a bottom electrode. When a voltage bias is applied between the nanotube and the bottom electrode, the devices act as very efficient electrical switches. Surface functionalization of the bottom electrode with a self-assembled monolayer is implemented to improve the switching reversibility. Moreover, it opens opportunities to use these CNT-NEMS as a vertical cross-bar junction for molecular electronics studies.

Direct Transmission Detection of Tunable Mechanical Resonance in an Individual Carbon Nanofiber Relay

“…Some prototype carbon NEMS have been reported in the literature, [4][5][6][7][8][9][10][11] but there have been relatively few experimental studies of the high frequency properties of carbon NEMS based on individual carbon nanotubes. [12][13][14][15][16] The resonance frequencies of doubly clamped suspended singlewalled nanotubes (SWNT) have been determined using an indirect mixing technique with a lock-in amplifier.…”

“…[12][13][14] The method requires a semiconducting nanotube and can therefore not be applied to the mechanically more rigid multiwalled nanotubes (MWNT) or nanofibers (CNF) that have been studied as a dc prototype NEMS and allow the fabrication of more varied device geometries. [4][5][6][7][8]10,11 The mechanical resonances of singly clamped MWNT have been observed in a field emission microscope, where the broadening of the field emission spot was observed as the nanotube was brought into mechanical resonance by the application of an ac voltage on a side gate. The resonance frequency of the MWNT could be tuned by an order of magnitude by increasing the bias voltage on the nanotube and thus increasing the tension.…”

Carbon-based nano-electro-mechanical systems

“…The differences in device geometries, such as larger air-gaps (~ 80 nm) and the use of MWNTs may be sufficient to explain the larger turn-on voltages required in that case. However, Dujardin 7 et al report low switching voltages of 2.8 V -3.0 V in their MWNTs cantilever structures, a result which can be attributed to the very shallow (4 nm) air gaps. We have also measured the switching times to be on the order of a few nanoseconds on these switches, 15 which is extremely attractive for high-frequency electronics applications.…”

“…Such exceptional mechanical properties arise from the sp 2 bonding character inherent to graphene from which many carbon-based nanostructures are derived, such as single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs) or CNFs. The success of CNT based NEMS has already been validated in a variety of applications ranging from nanotweezers, 5 memory devices, 6 nanorelays, 7,8 and resonators. 9 In this paper, we provide an overview of our work in forming NEMS switches which are comprised of laterally oriented SWNTs suspended over pre-fabricated trenches based on two-dimensional (2D) planar technology, as well as vertically oriented CNFs which are under consideration for three-dimensional (3D) NEMS.…”

Nonlinear resonance in a three-terminal carbon nanotube resonator

“…Such devices have since been successfully fabricated [9,10,11]. In [6,7,9,10,11] the device was considered mainly operating as a switch and transduction was based on a tunneling current between the tube tip and the drain terminal. In a subsequent publication [12] also the high frequency properties were considered and nonlinear resonant behavior was demonstrated.…”