Modeling a carbon-nanotube-based nanoelectromechanical relay

Licentiatavhandling, 2004

We have theoretically investigated the properties of a three-terminal carbon-nanotube-based nanoelectromechanical relay. The system operation is based on an coupling between electrical and mechanical degrees of freedom which is a typical characteristic of a NEMS device. Another is the small size of the system which typically is in the nanometer range. This small length scale and the extraordinary stiffness of carbon nanotubes imply that the intrinsic mechanical frequency of the system is in the GHz-range. We show that operation of the device as a switch in this frequency regime is feasible due to dissipative processes associated with tube-drain electrode interactions. Furthermore, the system responds resonantly to a narrow band of GHz-frequencies and the main resonance can be tuned by changing bias voltages. The effect of electromagnetic fields with frequencies in the resonance regime is also investigated, but, extraordinarily high field strengths are needed to affect the system. The influence of surface forces is calculated, and, they are shown to introduce design constraints to avoid the ubiquitous ``stiction problem'' in nano science. This problem can be alleviated by changing the design into one that relies on field emission charge transfer. This non-contact-mode design complements the former contact mode device, its properties are investigated, and we observe a qualitatively different behavior compared to the original design.