Ballistic transport and electrostatics in metallic carbon nanotubes

We calculate the current and electrostatic potential drop in metallic carbon nanotube wires self-consistently by solving the Green´s function and electrostatics equations in the ballistic case. About one-tenth of the applied voltage drops across the bulk of a nanowire, independent of the lengths considered here. The remaining nine-tenths of the bias drops near the contacts, thereby creating a nonlinear potential drop. The scaling of the electric field at the center of the nanotube with length (L) is faster than 1/L (roughly 1/L^1.25-1.75). At room temperature, the low bias conductance of larger-diameter nanotubes is larger than 4e²/h due to occupation of noncrossing subbands. The physics of conductance evolution with bias due to Zener tunneling in noncrossing subbands is discussed.