Inhomogeneous broadening and the breakdown of the quantum Hall effect in GaAs/AlGaAs

Abstract

The critical current for the breakdown of the quantum Hall effect at fixed filling factors has been observed to drop by more than a factor of ten when a GaAs/AlGaAs heterostructure is subjected to thermal cycling after exposure to a light pulse. Concurrent changes in the transport parameters suggest that the metastable, charged deep defect states in the doped AlGaAs layer, which are also responsible for the persistent photoconductivity effect, tend to increase inhomogeneities of the carrier density with thermal cycling and reduce the effective width for the current path in the quantum Hall regime.