ABSTRACT

In the 1980, most of the initial work on electron transport in a small system dealt with metal samples, in which many transverse sub-bands were involved and the transport was diffusive. At the same time, advances in semiconductor micro-technology made it possible to fabricate extremely high mobility quantum wires with narrow widths, in which only a few of the lowest sub-bands are occupied and the transport is ballistic. The allowed modes in the channel are then the "waveguide" modes. The so-called one-dimensional circuit means that the width of the circuit is narrow enough for the energy spacing between sub-bands produced by the transverse confinement to be much larger than the electron's longitudinal kinetic energy and there is only one mode of electron moving in the circuit. The single-mode movement of an electron is described by the plane wave function with the wave vector along the circuit's direction, which follows the quantum mechanics law.