Abstract

We have performed femtosecond emission experiments on resonantly created excitons in GaAs quantum wells (QWs) that give evidence for the contributions of resonant Rayleigh scattering and luminescence and, in particular, for the dynamics of the total secondary radiation as a function of exciton density.¹ Coherent Rayleigh scattering dominates at low densities and temperatures and displays a temporal shape independent of exciton density but entirely determined by the static disorder potential (interface fluctuations). At exciton densities larger than 10¹⁰ cm⁻², the rise time of the emission is strongly density dependent, demonstrating the importance of exciton-exciton scattering for the signal rise. As a result of these momentum scattering processes, we have conjectured that, at high densities, the emission is dominated by incoherent luminescence.¹

© 1998 Optical Society of America