Annealing-Induced Structural Evolution Of Inas Quantum Dots On Inp (111)A Formed By Droplet Epitaxy

We have studied the annealing-induced structural evolution of uncapped InAs quantum dots (QDs) on InAlAs/InP(111)A substrates formed by droplet epitaxy. The annealing of uncapped InAs QDs results in the outflow of InAs from the QDs, forming two-dimensional InAs. The outflow of InAs from QDs is suppressed when the coverage of the two-dimensional InAs reaches a certain saturation thickness. After annealing at 370 degrees C, the saturation thickness is less than 1 monolayer (ML). The outflow of InAs is suppressed after two-dimensional InAs forms only around the QDs to a certain limited extent. The QDs remain after annealing when the original size of the QDs before annealing is sufficiently large. After annealing at 470 degrees C, the saturation thickness is around 1 ML. The outflow of InAs continues until a 1 ML-thick, two-dimensional InAs layer covers nearly the entire surface. The QDs remain after annealing when the total amount of supplied InAs is sufficiently large. The InAs QDs after capping exhibit efficient photoluminescence (PL) emission at around telecommunication wavelengths. We also observed PL emission from the 1 ML-thick two-dimensional InAs.