InGaAs/GaAs hybrid quantum well-dot nanostructures: Impact of substrate orientation and recombination mechanisms

We study the impact of substrate orientation on growth of quantum well-dots (QWD) hybrid low dimensional structures that are intermediate in properties between quantum wells and quantum dots. QWD are formed by thickness and composition modulations of InGaAs quantum well, which localize electrons and holes. We show that in case of growth on 6 degree misoriented substrates such modulations are much more pronounced than in case of growth on exact oriented substrate. The modulations result in efficient strain relaxation, which allows vertical stacking of at least fifteen 8 ML-thick In0.4Ga0.6As QWD layers without dislocation formation. Fitting of experimental dependencies of integrated PL intensity on excitation power by using ABC model allowed us determining relative contribution of different recombination processes.