Carbon Nanotube Structure, Electronic, and Transport Properties

Abstract

The last few years witnessed a dramatic increase in nanomaterial and nanotechnology research. Among others, one of the most exciting fields to emerge is nanoelectronics [1--4], where a myriad of possibilities are appearing in the form of sensors [5], actuators [6], and transistors [7--9], each characterized by feature sizes of the order of a few nanometers. All this innovation has been fueled by the discovery of new materials and the invention of manufacturing methods that allow design and development at such a minute scale. Carbon nanotubes (CNTs) are at the forefront of these new materials, due to the unique mechanical and electrical properties that give them, e.g., exceptional strength [10] and conductivity [11]. Moreover, these nanotubes exhibit a tremendous current-carrying ability [12], potentially allowing for increased miniaturization of high-speed and high-power circuits. CNT molecules have a cylindrical structure and are formed by one or more concentric, crystalline layers of carbon atoms. These atoms are assembled in hexagonal-lattice graphene sheets, which are rolled up into seamless tubes and named according to the number of concentric sheets as being either multi or single-walled nanotubes. Both kinds were originally observed experimentally, via transmission electron microscopy, decades ago, the research work on which in the field has subsequently increased dramatically.