THE INFLUENCE OF EXCITON MIGRATION ON PHOTOLUMINESCENCE LIFETIME IN GROWTH-INTERRUPTED GAAS ALAS SINGLE QUANTUM-WELLS/

We have used resonant and non-resonant, low temperature, picosecond ti me-resolved spectroscopy to investigate exciton migration in a GaAs/Al As single quantum well grown by molecular beam expitaxy with growth in terruption and post-growth hydrogen passivation. Excitons migrate with a time constant around 1500 ps from the narrower to the wider well re gions depopulating the narrower regions in favour of the wider regions and this results in a faster decay time. This process is also demonst rated by the photoluminescence spectrum with a large enhancement in th e emission intensity of the wider regions when the narrower well regio ns are resonantly excited.