Optical-microwave study of electron-exciton dynamics in undoped GaAs/AlGaAs quantum wells

Abstract We report on a comparative study of the photo-induced microwave absorption (PMA) and photoluminescence (PL) in undoped GaAs/AlGaAs QWs having various well widths (50–200 A). While the PL and its excitation (PLE) spectra probe the excitonic transitions, the PMA and its excitation (PMAE) spectra provide information on free electron hole generation processes. The PMAE spectrum shows the excitonic bands, and they are interpreted in terms of Auger-like and thermal exciton dissociation. The electron in-plane mobility is studied by classical cyclotron resonance (CR). The PMAE and CR dependencies on temperature, microwave power and modulation frequency are interpreted in terms of carrier and exciton localization in the spatially fluctuating QW potential.