Magnetotransport studies of charge accumulation in an AlInAs/GaInAs tunneling structure

We report a study of the current-voltage characteristics of a double barrier, lattice matched, quantum well tunneling structure in a quantizing magnetic field (B∥J). Experiments were conducted at fields up to 23 T at 1.5 K. The heterostructure investigated had 400 Å spacer layers in the emitter and collector, a barrier width of 72 Å, and a 43-Å-wide quantum well. This structure showed one negative differential resistance region with a peak-to-valley ratio of 23 at 4.2 K. We observed magnetoquantum oscillations, periodic in 1/B, associated with tunneling from a quantized state in the emitter. The overall magnetoconductance dramatically changed with applied bias. We associated these variations with a field-induced increase of the impedance of the undoped spacer layers. The frequency of these oscillations increased linearly with applied bias. A discontinuity in this dependence is observed around the peak bias voltage which is the direct result of the dynamical storage and release of charge in the well.