Time resolved magneto-optical spectroscopy on InGaAs nanostructures grown on (311) A and (100)-oriented substrates

We present a time-resolved magneto-photoluminescence study of In0.5Ga0.5As self-organized nanostructures grown on (100) and (311) A-oriented substrates by molecular beam epitaxy. The (311) A-oriented samples have a corrugated surface realizing a sort of quantum wire array, whereas the (100) samples exhibit Stranski-Krastanow islands. The different morphology of the nanostructures is reflected in the different electron/hole wave-function confinement along the three directions (perpendicular and parallel to the growth direction). We discuss the effects of the magnetic field (up to 8 T) on the recombination mechanism in these InGaAs nanostructures and on the transient dynamics of photoluminescence. We observe a clear decrease of the photoluminescence decay time with magnetic field flux indicating the exciton nature of the radiative low-temperature recombination processes. (C) 1999 American Institute of Physics. [S0003-6951(99)04004-8].