Carbon Nanotube Nanoelectromechanical Systems

Abstract

Since the discovery of carbon nanotubes high hopes were placed on their possible applications. They were expected to revolutionize our technology and indeed, CNTs have proven to be a good material for applications in electronics, such as channels in field effect transistor and optoelectronic devices. In order to realize future nanotube electronic and electro‐mechanical systems, it is not only necessary to thoroughly understand the underlying physical phenomena of both single as multi‐walled carbon nanotubes (MWNTs), but also to be able to fabricate devices possessing the desirable qualities. Many efforts of this work were dedicated to nanotube manipulation and nanofabrication in order to integrate carbon nanotubes in current fabrication processes and achieve novel type of devices. The device fabrication is described in the Annex A. In the thesis various attempts to experimental realization of CNT‐based nano‐electromechanical systems are shown. Typically, the CNT devices presented later in this thesis operate in so‐called transistor geometry, which is why it is important to understand principles of operations of CNTFETs, explained above in Chapter 1. Then, Chapter 2 brings a short introduction to structural and electronic properties of CNTs and graphene, ways of synthesis and methods used for characterization. The Chapter 3 is an introduction to micro and nanoelectromechanical systems, focusing carbon nanotube resonators and motors. In the second part of the thesis carbon nanotube resonators are studied. To perform the measurements the so‐called mixing technique was used, explained in Annex B. In Chapter 4 a giga‐hertz operation frequency resonator based on ultra‐short SWNT is presented. Also influence of nanotube length and temperature on the resonator frequency and principles of mass sensing are discussed. In Chapter 5 MWNT resonators of different diameters are measured with emphasis of frequency as a function of a number of shells. The number of shells can be reduced using the electrical breakdown technique and the MWNT resonator eigenmodes can be approximated using the elastic beam theory, which is in details explained in the Annex C. The third part of the thesis is dedicated to carbon nanotube motors. First of all, in Chapter 6 different approaches to fabricating micro‐scale heaters are presented in order to realize controlled thermal gradient motor. Suspended micro‐heaters based on platinum and gold are presented, as well as non‐suspended heaters based on highly‐doped silicon. In Chapter 7, a novel type of graphene‐based heating is shown. For all types of heaters fabrication, characterization and integration with CNT motor is discussed. Finally, in Chapter 8 an intention of realization of CNT electron windmill is presented.

Date of Award	29 Jun 2012
Original language	English
Supervisor	Adrian Bachtold (Director)