Investigation of parallel conduction in GaAs/ AlxGa1-xAs modulation-doped structures in the quantum limit

We present a detailed study of the transport in GaAs/ AlxGa1-xAs modulation-doped structures in the low field and high magnetic field quantum limit for varying amounts of parallel conduction in the AlGaAs region. We observe the apparent breakdown of quantum Hall effect behavior due to low mobility carriers in the parallel channel. The onset of conduction through the parallel channel by quantum transport measurments has been observed, along with a non-linear dose dependence due to photoexcitation.