Shape stabilization and size equalization of InGaAs self-organized quantum dots

We report a simultaneous shape stabilization and size equalization after shape transformation of InGaAs self-organized quantum dots (QDs) formed via a fractional monolayer (ML) deposition technique. The density of QD increases rapidly from an initial value of 110 +/- 10/mu m(2) (at a total deposition of 4 ML) to 270 +/- 30/mu m(2) (at 5 ML) and saturates at a level of 240 +/- 20/mu m(2) (at 10 ML). At an intermediate stage of 7 ML deposition, bimodal QD height (peaked at 8.5 nm and 14.5 nm) and aspect ratio (peaked at 0.18 and 0.26) distributions occur, confirming the QD shape transformation from a shallower to a steeper shape. The eventual convergence in lateral size, height and aspect ratio is the direct result of the simultaneous QD size equalization and shape stabilization. The QD size and shape evolution is also substantiated by the Iom temperature (4 K) photoluminescence (PL) data taken from samples with QDs capped by GaAs.