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.