A novel approach in fabrication and study of laterally quantum-confined resonant tunnelling diodes

A novel fabrication process, based on selective wet etching and photolithography, has been developed to produce quantum wire resonant tunnelling diodes contacted via a free-standing GaAs bridge. Current-voltage characteristics of quantum wire resonant tunnelling diodes have been studied at 300 mK in the presence of a magnetic field oriented either parallel to or perpendicular to the current. For the smallest device, in the presence of a magnetic field oriented perpendicular to the current and parallel to the wire, we are able to deduce the probability density of the lowest three bound states from the magnetic field dependence of the current and show that the one-dimensional confining potential is close to parabolic. In the presence of a magnetic field oriented parallel to the current a continuous transition from electrostatic (at low field) to magnetic (at high field) confinement is observed.