Photo-induced resistance resonance effect in modulation doped GaAs/AlGaAs heterostructures

We report the observation of a photo-induced resistance resonance effect in MBE-grown GaAs/AlGaAs heterostructures with a Si planar-doped layer at the AlGaAs side, near the interface. The effect is characterized by a minimum in the photoconductivity as a function of the light dosage. We show, based on self-consistent calculations in the effective mass approximation, that t he minimum in the photoconductivity originates from the quantum coupling be tween the electron channel at the interface and the electron channel at the planar-doped region. The tuning of the resonance effect is provided by the internal electric field caused by the optically induced ionization of the DX centers at the planar-doped region.