Transport in a superlattice of 1D ballistic channels

Abstract

The authors have fabricated a 2D array of 1D narrow channels in a square lattice configuration on a high mobility GaAs/GaAlAs heterostructure. When a gate voltage is applied the underlying two-dimensional electron gas is depleted creating 4000 dots, of size 0.2 mu m, leaving a grid-like conducting path of quasi one-dimensional channels that are linked every 0.5 mu m. For low values of magnetic field the Hall voltage measured on either side of the device is quenched across its entire width of 25 mu m. The longitudinal magneto-resistance reveals Aharonov-Bohm oscillations with a flux period of h/e for magnetic fields up to 0.4 T. The conductance versus gate voltage shows structure that is consistent with Bragg reflections of the electron waves when the one-dimensional subband wavelength at the Fermi energy, in the direction of current flow, is equal to one superlattice period. Dips in the conductance when this criteria is met show a ln T temperature dependence, similar in origin to a 2D quantum interference. A magnetic field quenches these dips when the cyclotron orbit is comparable with the superlattice period.