TABLE OF CONTENTS Given the semiconducting character of two thirds of carbon nanotubes, their high aspect ratio and structural robustness, it is natural to ask if semiconducting carbon nanotubes can be used as active elements in nanoscale electronic devices. Indeed, there has now been many demonstrations of such devices, ranging from two-terminal rectifiers to field-effect transistors. These demonstrations have spurred tremendous interest in the field of carbon nanotube electronics for several reasons. First, for a single nanotube device, the channel width is on the order of one nanometer, much smaller than state-of-the-art silicon transistors, promising higher device densities. Second, carbon nanotubes have low defect density, and electronic transport is expected to be less affected by defect scattering. Third, the carrier distribution is not as sensitive to temperature variations due to the van Hove singularities at the band edges. Finally, quantum confinement should be easier to achieve because of the small channel width, and thus single-electron devices should be more readily available. Balancing these advantages is the fact that the knowledge base, fundamental understanding, fabrication infrastructure, and device design are much less developed for carbon nanotubes compared to silicon. For example, while some of the fabricated carbon nanotube devices bear resemblance with traditional silicon devices, this chapter emphasizes the much different physics that governs the operation of the carbon nanotube devices. We have already seen in the previous chapter how one part of a carbon nanotube electronic device the contacts behaves much differently from that in conventional materials. The current chapter goes beyond these...
