Carbon nanotube electronics

We first discuss the one-dimensional (113) electronic structure of carbon nanotubes (CNTs) and its influence on the carrier scattering mechanisms in metallic CNTs. We then focus our attention on semiconducting CNTs and CNT-based electronic devices. We start by discussing the structure and function of p-type field-effect transistors (CNTFETs). Then the preparation and properties of ambipolar CNTFETs is described. We show that in addition to doping with donor atoms, n-type transistors can be generated by simply annealing the p-CNTFETs in vacuum. The latter process is reversible upon oxygen exposure. We propose that the commonly found p-character of the as-prepared CNTs is neither an intrinsic nanotube property nor does it reflect their doping, but is determined by the nature of carrier injection at the contacts. The ability to generate both p- and n-CNTFETs allows us to build complementary logic circuits. We present results on two voltage inverters ("NOT gates"), an intermolecular one and an intramolecular one. In the latter, the logic function is encoded along the length of a,single CNT or CNT bundle. Finally, we focus on the electronic properties and device fabrication in composite CNT systems, i.e., multi-walled (MW) and single-walled (SW) CNT bundles. We discuss the current-induced breakdown process in these materials and use it to: (a) take apart shell-by-shell MWCNTs and electrically characterize each shell, (b) develop the process of "constructive destruction" which allows the fabrication of arrays of CNTFETs out of bundles of SWCNTs without the need to first separate metallic from semiconducting nanotubes. (C) 2002 Elsevier Science B.V. All rights reserved.