Conduction in n⁺-GaAs Wires

Abstract

For clear observation of interference between waves it is a necessary condition that the waves must maintain a constant phase relationship with respect to each other. This coherence is easily achieved with laser sources in optics. In metals and semiconductors coherence can be lost either by thermal smearing of the Fermi level or by the presence of inelastic scattering and so it is best achieved at low temperatures. Such interference phenomena have been observed in multiply-connected structures at low temperatures¹. However, even in a simple wire the electrical resistance is modified by interference between scattered electron waves. Thus an ensemble of wires all prepared in identical macroscopic fashion would not all have the same resistance since the microscopic configuration of scatterers, which defines the interference paths, will be different for each wire. The application of a magnetic field changes the flux through each loop formed by the interfering waves and hence introduces a phase difference between the electron waves so that the magnetoresistance of each wire fluctuates as the field increases. Since the size and distribution of interference loops is determined by the microscopic scattering configuration, each wire has a unique magnetoresistance or “magnetofingerprint”.