Annealing Effect on the Formation of In(Ga)As Quantum Rings From InAs Quantum Dots

The correlation between the In(Ga)As quantum rings (QRs) and their precursors InAs quantum dots (QDs) are studied by changing the annealing time after the deposition of a thin InAs layer on GaAs. The atomic force microscopy and photoluminescence (PL) are used to characterize the morphologies and electronic states of QDs and QRs. The longer annealing time tends to enlarge the QD size to high aspect ratio, group InAs islands into several different sizes, and red-shift the PL peak. The resultant QRs show the ridge-confined rings and the PL peaks of QRs blue-shift with increasing QD aspect ratio. It demonstrates an important way to tailor the electronics states of QRs.