Mobility enhancement in highly doped GaAs quantum wells

We propose the mechanism of the mobility enhancement in highly doped semiconductor quantum wells, based on the large increase in the carrier concentration using the field effect and on the corresponding reduction of the ratio of the ionized impurity concentration to the electron concentration. We observe the mobility enhancement in GaAs quantum wells doped at ∼2×1018 cm−3 at 77 K from 572 cm2/V s under the equilibrium conditions to approximately 2500 cm2/V s when a large carrier concentration is induced into the quantum well in a field‐effect transistor. This effect can be used to increase the voltage and current swing in modulation‐doped structures and may also allow us to achieve the mobility enhancement in new semiconductor materials with inherently large defect densities.