Nanotubes for Nanoelectronics

Carbon nanotubes (CNTs) have emerged as a viable electronic material for molecular electronic devices because of their unique physical and electrical properties [1–7]. For example, nanotubes have a lightweight and record-high elastic modulus, and they are predicted to be by far the strongest fibers that can be made. Their high strength and high flexibility are unique mechanical properties. They also have amazing electrical properties. The electronic properties depend drastically on both the diameter and the chirality of the hexagonal carbon lattice along the tube [8–10]. Carbon nanotubes were discovered by Iijima in 1991 at the NEC Fundamental Research Laboratory in Tsukuba, Japan [1]. Using a transmission electron microscope (TEM), he found carbon tubes consisting of multiple shells (see Fig. 1). These early carbon tubes are called multiwall nanotubes (MWNTs). Since then, extensive research has been focused on synthesis and characterization of carbon nanotubes. In 1993, Ijima’s group [11] and Bethune et al. [12] at IBM Almaden Research Center at San Jose, California, synthesized carbon nanotubes with a single shell, called single-wall nanotubes (SWNTs). Because of their simple and well-defined structure [13], the single-wall nanotubes serve as model systems for theoretical calculations and for critical experimental studies. Since then, the physical and electrical properties of carbon nanotubes have been studied extensively. Only a few years ago, people began to utilize carbon nanotubes’ unique electrical properties for electron device applications. Up to now, there has been no extensive review to cover the progress in nanoelectronic devices using carbon nanotubes. In this chapter, I aim to present extensive review on progress in electronic structure and transport properties of carbon nanotubes and nanoelectronic devices based on carbon nanotubes ranging from quantum transport to fieldeffect transistors. This chapter is organized as follows. It begins with brief review of the progress in microand nanoelectronic devices prior to carbon nanotubes (Section 2). Then the synthesis and physical properties of carbon nanotubes will be discussed in Section 3. Nanoelectronic devices based on carbon nanotubes including single-electron transistors (SETs), field-effect transistors, logic gates, and memory devices will be reviewed in Sections 4 and 5. The chemical doping, junctions, and metal–nanotube contacts will be described in Section 6. Finally, nanofabrication based on carbon nanotubes including controlled growth and selective placement of nanotubes on patterned Si substrates will be reviewed in Section 7. Since the discovery of carbon nanotubes, over 1000 papers on carbon nanotubes have been published. It is unlikely that every paper will be included in this chapter, because most papers dealt with synthesis, physical, and chemical properties of nanotubes. In this chapter, I will focus on electrical properties of nanotubes, nanoelectronic devices constructed with nanotubes, and nanotube-based nanofabrication.