Elimination of carrier-density nonuniformities by surface acoustic waves

The action on a two-dimensional electron gas (2DEG) by electric fields that accompany surface acoustics waves (SAWs) propagating in GaAs-AlxGa1-xAs heterostructures is typically negligible because of screening. In the quantum Hall regime, the longitudinal conductivity of the 2DEG is nearly zero when the Fermi level lies in the Landau gap. Consequently, the SAWs can build up electric fields that are strong enough to rake off mobile electrons. We demonstrate that inhomogeneous carrier distributions produced in the course of photoionization of DX centers can be flattened out by applying the SAWs in high magnetic fields. (C) 2000 American Institute of Physics. [S0003-6951(00)01816-7].