Transport characteristics of series ballistic one-dimensional channels with small separation

Abstract

Series ballistic one-dimensional (1-D) channels with a separation (L sp) of 200 nm and 400 nm are fabricated by focused Ga ion beam scanning. For the L sp=400 nm sample, step structures similar to those of a single ballistic channel are observed in resistance-gate voltage (V g) characteristics. Although plateau resistances are larger than quantized resistance values (R n) at zero magnetic field, they decrease and approach R n as the magnetic field increases. On the other hand, for the L sp=200 nm sample, resistance oscillates as a function of V g. This oscillation originates from zero-dimensional (0-D) states in the structure. Furthermore, a new resistance oscillation that probably corresponds to 0-D energy levels crossing with magnetic fields is clearly observed for the L sp =200 nm sample.