The influence of exciton migration on photoluminescence lifetime in growth-interrupted GaAsAlAs single quantum wells

We have used resonant and non-resonant, low temperature, picosecond time-resolved spectroscopy to investigate exciton migration in a GaAsAlAs single quantum well grown by molecular beam epitaxy with growth interruption and post-growth hydrogen passivation. Excitons migrate with a time constant around 1500 ps from the narrower to the wider well regions depopulating the narrower regions in favour of the wider regions and this results in a faster decay time. This process is also demonstrated by the photoluminescence spectrum with a large enhancement in the emission intensity of the wider regions when the narrower well regions are resonantly excited.