Electronic properties of a carbon nanotube in a field-effect transistor structure: A first-principles study

A first-principles electron-state calculation is performed to explore the electronic properties of a semiconductor carbon nanotube (CNT) in a field-effect transistor structure. Field-effect electron/hole doping results in a carrier distribution spread over the whole C-C network of the CNT, while accumulated charges, that explain the electrostatic capacitance C₀ between the CNT and gate electrode, are concentrated in a small part of the CNT facing the gate electrode. We also demonstrate that the density of states structure of the CNT gives substantial bias dependences to the total capacitance C of the system.