GaAs quantum cascade laser spectroscopy by tunnelling magnetotransport

Pulsed field magnetotransport measurements up to 50T were performed on GaAs /GaAlAs quantum cascades structures at liquid helium temperatures. Current- voltage measurements show a staircase profile enhanced dramatically by a co nstant magnetic field. This profile is tentatively explained by resonant tu nnelling transport processes into the active well subband levels, Moreover, a novel series of quantum oscillations periodic with reciprocal of the mag netic field was found in magnetoresistance measurements. These oscillations provide a direct determination of the active quantum well subband energies . (C) 2001 Elsevier Science B.V. All rights reserved.