Charged excitonic complexes in GaAs/Al0.35Ga0.65As p-i-n double quantum wells

Photoluminescence (PL) and PL excitation measurements (PLE) have been perfo rmed in GaAs/AlxGa1-xAs double quantum well (QW) structures under different applied electric fields. An emission due to charged excitons (trions) has been identified in the PL spectra similar to 3 meV below the heavy-hole exc iton emission. These trions are localized by random potential fluctuations, at the interfaces or in the QW, as shown by the saturation of their emissi on intensity with respect to that of the heavy-hole excitons. Trions are po sitively charged, namely, they are made by two holes and one electron, as s hown by (i) an analysis of the PL polarization for resonant excitation of t he heavy- and the light-exciton ground state, and (ii) the analysis of the Zeeman effect for the trion PL band in the Faraday geometry, i.e., for a ma gnetic field normal to the QW's.