Field ionised impurity scattering in an AlGaAs/GaAs two-dimensional electron gas

Low field-mobility saturation has been observed in AlGaAs/GaAs heterostructures. Under illumination, the mobility decreases and the carrier concentration increases at high fields. Both effects are thought to be due to ionisation of a centre in the GaAs, probably oxygen. The experimental results are explained in terms of a simple trap model.