TRANSPORT CHARACTERISTICS OF SERIES BALLISTIC ONE-DIMENSIONAL CHANNELS WITH SMALL SEPARATION

Series ballistic one-dimensional (1-D) channels with a separation (Lsp) of 200 nm and 400 nm are fabricated by focused Ga ion beam scanning. For the Lsp=400 nm sample, step structures similar to those of a single ballistic channel are observed in resistance-gate voltage (Vg) characteristics. Although plateau resistances are larger than quantized resistance values (Rn) at zero magnetic field, they decrease and approach Rn as the magnetic field increases. On the other hand, for the Lsp=200 nm sample, resistance oscillates as a function of Vg. 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 Lsp=200 nm sample. © 1990.