Charge screening in the quantum Hall regime probed by the lateral photoelectric effect

Electrons are photoelectrically injected into the two-dimensional electron system (2DES) near a standard AlGaAs–GaAs heterojunction by a focussed light spot. The photovoltage in the plane of the 2DES exhibits quantum oscillations with magnetic field that are basically out of phase with respect to the oscillations of the conductivity sxx. This is evidence for the influence of screening effects on the injected charge. At low filling factors a dip is superimposed on the maxima, which points to a competition between screening properties and the expected diffusion effects.