Evaluation of electron-phonon coupling of Al0.27Ga0.73As/GaAs quantum wells by normal incidence reflectance

In the present work we present results of normal incidence reflectance applied to a Superlattice (SL) grown by Molecular Beam Epitaxy (MBE), containing ten 53 Å thick GaAs Quantum Wells (QW's), separated by 53 Å thick Al0.27Ga0.73As barriers. Here we perform a detailed analysis of the optical absorption line shapes as well of the peak exciton positions as a function of the sample temperature, to obtain a direct evaluation of the interaction between the QW's states and the lattice vibrations. The obtained results are then analyzed with some detail and compared with current electron-phonon (e-ph) schemes so far applied to Multiple Quantum Wells (MQW) systems. In particular, the Elhh 1s exciton peak moves with temperature interacting with an acoustical phonon of h?? ? 20.8 meV as the GaAs bulk gap, while the broadening of the same peak is dominated by a SL optical phonon mode for which h?? ? 34.9 meV.