The transition from two-stage to three-stage evolution of wetting layer of InAs/GaAs quantum dots caused by postgrowth annealing

For the InAs/GaAs quantum dot (QD) system, the evolution of wetting layer (WL) with InAs deposition thickness has been studied under different postgrowth annealing (PGA) durations using reflectance difference spectroscopy. For the sample without PGA, WL thickness remains constant after the formation of QDs, exhibiting a typical two-stage evolution, whereas for the samples with PGA, WL thickness continuously increases linearly with a reduced slope after the formation of QDs and is fixed in ripening growth, indicating a three-stage evolution. By adopting a theoretical model, we have well simulated the two kinds of evolution and found that the variations of QD’s morphology and the interaction of QDs occurring during PGA lead to the different evolution behaviors of WL.