Structural and optical properties of In(Ga)As∕GaAs quantum dots treated by partial capping and annealing

Abstract

We tune the emission energy of self-assembled InAs∕GaAs(001) quantum dots (QDs) by partial GaAs capping and annealing. During the annealing step, the surface above the QDs flattens substantially. The existence of In-rich cores below the thin GaAs cap is directly probed by using in situ selective etching. The blueshift of the QD emission energy, resulting from the reduction of the QD height, is tuned by increasing the annealing time or by reducing the capping layer thickness. For long annealing times, the ensemble photoluminescence (PL) displays a multipeak behavior which is attributed to monolayer fluctuations of the QD height. Single-QD micro-PL shows that the quality of the QDs can be improved by desorbing the In accumulated around the QDs by performing the annealing at high substrate temperatures.