High spin polarization of optically-oriented trions in p-doped GaAs-AlGaAs quantum wells.

We performed cw-photoluminescence (PL) measurements on a 15 nm wide p-doped Al0.3Ga0.7As-GaAs-Al0.3Ga0.7As quantum well structure at low temperatures. By irradiating the sample with circularly polarized light and analyzing the degree of circular polarization of the PL signal, we found a significantly higher degree of spin polarization for charged excitons (trions) than for neutral excitons. Time-resolved pump-probe and Faraday-rotation experiments give an additional information concerning the exciton and trion resonant photoexcitation. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]