Lateral ambipolar drift of the excess charge carriers in the GaAs-based heterostructures with quantum wells and impurity δ-layers in the adjacent barriers

Abstract

The low-temperature ambipolar photoconduction in the InGaAs/GaAs and GaAs/AlGaAs heterostructures containing the compositional quantum well (QW) tunnel-coupled with the impurity δ-well have been studied under a wide electric field range. The “stretched” bipolar drift length in the InGaAs/GaAs structure is shown to achieve a few mm at the fields of ∼70 V/cm and exceed that in the GaAs/AlGaAs structure at the comparable field strength by half an order of magnitude. The photoconductivity decay is up to several tens μs long and its behavior is fitted by the single- and “stretched-" exponent functions. The obtained results are shown to be caused by spatial separation of the non-equilibrium charge carriers in the potential profile engineered by such QW configuration and the dispersion law of holes in them.