Resonant tunneling in crossed electric and magnetic fields in GaAs-AlAs superlattices.

Abstract

We employ time-dependent photocurrent measurements to study resonant tunneling in a magnetic field parallel to the layers in two differently coupled superlattices. The shift of the resonance between the first and the second electronic subbands is proportional to the square of the magnetic field. The shift is quantitatively in agreement with theoretical calculations, taking into account the polarization of the wave functions due to the electric field. A decrease in the tunneling times at resonance with increasing magnetic field is found in the sample with stronger coupling while the weakly coupled sample shows an increase. For the weakly coupled sample, stationary photocurrent and photoluminescence measurements are alternative but less precise methods of studying resonant tunneling in a parallel magnetic field.