Theoretical model of giant oscillations of the photocurrent in GaAs/AlAs p-i-n diodes

Abstract

p-i-n semiconductor heterostructures are common optoelectronic devices with numerous applications hinging on the non-trivial kinetics of photoexcited charge carriers within them. One such effect manifests itself as an oscillation of the photocurrent versus the applied bias voltage and has been qualitatively studied recently. However, a model that would explain the experimentally observed magnitude of the oscillations is, to the best of our knowledge, still absent. In the present work we consider a model wherein electrons from the highly-doped p-region are resonantly captured into 2D states of the triangular quantum well formed by the undoped i-region via scattering on impurities. We find that the rate of capture into 2D states is determined by the form of the wave function of these states and increases sharply when the tail of the wave function penetrates deeply into the highly doped region, resulting in a sharp increase in the photocurrent. Our analysis of the dependence of the positions of the photocurrent maxima versus bias voltage shows good agreement with experiments and confirms the applicability of our model.