Ripening of self-organized InAs quantum dots

The temporal evolution of the size and the shape of self-organized InAs/GaAs quantum dots (QDs) grown using MOCVD is investigated. During a growth interruption after the deposition of the QD material a ripening process is observed, where some QDs grow at the expense of other QDs. A multimodal distribution of the QD ground-state transition energies is observed and attributed to QDs differing in height by entire numbers of atomic monolayers. This distribution is used to track the evolution of the QD ensemble during the growth interruption more detailed. A shape transition from very flat, truncated-pyramid-like QDs to higher, more pyramidal QDs is suggested. An additional antimony flux at the end of the growth interruption leads to an accelerated ripening resulting in a significant red shift of the QD luminescence, which is explained by the surfactant properties of antimony on InAs.