Investigation of electronic transport in carbon nanotubes using Green’s-function method

Abstract

We have investigated the fundamental transport characteristics in carbon nanotubes (CNTs) in order to realize a high-frequency device. In the present analysis, the electron and hole densities are excited at each lead and propagate as a wave from the left contact to the right contact in the CNTs. First, we applied Green’s-function method formulation to CNTs with arbitrary chirality. We then calculated the basic conductive characteristics in the CNTs. In the metallic and intrinsic CNTs, the assumption of a linearly varying potential distribution is valid because the electron and hole densities satisfy the charge neutrality condition, and their distributions become uniform. We evaluated the I-V characteristics of semiconductive and metallic CNTs. Based on the obtained results, we can control the differential conductance from a negative value to a value of several times the conductance quantum by means of chirality, Fermi level, and bias voltage. We evaluated the GV∕I-V characteristics of the zigzag CNT and found that when the group velocity of a mode with a real wave vector is comparable to that of another mode, GV∕I takes a maximum at V0, which corresponds to the transition between these modes.