Screening properties of a two-dimensional electron gasaround integer filling factors

摘要

Magneto-optical emission of a two-dimensional electron gas inmodulation-doped GaAs/GaAlAs single hetero-structures reveals intensitychanges associated to the ground-state filling factor. In particular, therecombination of electrons in the second confined sub-band with photoexcitedholes trapped at Be acceptors shows a rich structure determined bythe Landau-level occupancy of the lowest electron sub-band. Below fillingfactor 2 the free-hole recombination appears abruptly, as in Be-free samples,at a magnetic field which depends on the Be distance to the hetero-junction.The present results give information about the filling factor dependentscreening properties of the electron gas, which are thought to determine theobserved non-linear properties in the magneto-optics.