Optical-phonon scattering and theory of magneto-polarons in a quantum well in a strong magnetic field

We report a theoretical study of the carrier relaxation in a quantum-well structure subjected to a strong magnetic field. Both the alloy (GaInAs) disorder effects and the Fröhlich interaction are taken into account when the electron energy differences are tuned to the longitudinal optical (LO) phonon energy. In the weak electron-phonon coupling regime, a Fermi’s golden rule computation of LO phonon-scattering rates shows a very fast nonradiative relaxation channel for the alloy-broadened Landau levels (LL’s). In the strong electron-phonon coupling regime, we use a magneto-polaron formalism and compute the electron survival probabilities in the upper LL’s including increasing numbers of LO phonon modes for a large number of alloy disorder configurations. Our results predict a nonexponential decay of the upper-level population once electrons are injected in this state.