LO PHONON SIDE-BAND PHOTOLUMINESCENCE IN PURE GAAS AND GAAS ALGAAS QWS/

We report on a comparative study of the LO-phonon sidebands in pure bu lk GaAs and in undoped GaAs/AlGaAs quantum wells (QW). The 1LO- and 2L O-phonon assisted polariton photoluminescence (PL) line shape in bulk GaAs is investigated as a function of excitation energy and intensity and also of the lattice and (hot) electron temperatures. The line shap e analysis shows that the polariton distribution can be characterized by a low polariton temperature which can be very close to the bath tem perature (at 1.9 K). In GaAs/AlGaAs QWs the LO-phonon assisted PL is d ue to the recombination of localized geminate electron-hole pairs.