Self-assembled quantum dots: five years later

Self-assembled quantum dots (QDs) have been grown with good reproducibility by molecular beam epitaxy with up to five well-resolved zero-dimensional interband transitions measured by state-filling spectroscopy. The intersublevel energy spacing is shown to be readily tunable by adjusting the temperature of the substrate during the growth of the QDs and/or of the cap layer, or with post-growth annealing. The uniformity of InAs/GaAs QDs is optimized by studying the growth parameters affecting the equilibrium shape such as the amount of strain material deposited and the annealing time following the InAs deposition allowing the QDs ensemble to evolve. Such uniform QDs are also obtained for samples with multiple stacked layers. This allows us to study the effects of charged carriers, of tunneling between coupled QDs, of electrical injection, and of lasing in QDs with well-resolved excited states having adjustable intersublevel energy spacing. (C) 1999 Academic Press.