Magnetotransport of electrons in overfull quantum well

We report magnetotransport properties of electrons in a new kind of two-dimensional electron system (2DES)—a narrow single quantum well with electron density so large that the electrons splash out of the well. We show that the system is a two-component 2D electron gas consisting of very low mobility View the MathML source main part of the electrons and very small fraction (about 1% of all) of the electrons with much higher (10 times) mobility. The anomalous behavior of the magnetoresistance ρxx and Hall resistance ρxy of this system was observed. The sharp change of the transport properties at the moment of overfilling of the quantum well gives the possibility to determine the value of the band offset ΔEc on the interface Al0.3Ga0.7As/GaAs using the results of the self-consistent calculation of the energy diagram of the studied structure. As the result we have obtained ΔEc=(0.18–0.20)eV. This value is significantly less than the well-known View the MathML source found in optical experiments.