Comparison of quantum-confined Stark effect in interdiffused and abrupt GaAs/AlGaAs quantum wells

Abstract

Photocurrent measurements at room temperature have been carried out on thermally interdiffused GaAs/AlGaAs multiple quantum well structures. Although quite comparable, the Stark shift (quantum-confined Stark effect) in the disordered well is smaller than in the as-grown well. These measurements are consistent with calculations of the electron–heavy hole displacement versus electric field for infinite and square well models for the as-grown well, as well as parabolic and error function well models for the disordered well. We observe that this displacement increases faster for the wells with graded barriers which fit the experimental disordered well. Consequently, the exciton binding energy is smaller, which is consistent with the reduction of the Stark shift revealed by the photocurrent measurements.