Anomalous photomagnetoresistance effect in modulation-doped AlGaAs/GaAs heterostructures.

It is shown that this effect is associated with photoexcitation of electrons from DX centers in the highly doped AlGaAs region resulting in the creation of a second conducting layer of high charge density and low mobility. The applied magnetic filed, which has little effect on the conductivity in AlGaAs because of the low electron mobility there, gives rise to a series (Hall) resistance in the GaAs channel circuit.