Self organized defect free InAs/GaAs and InAs/InGaAs/GaAs quantum dots with high lateral density grown by MOCVD

We report on the growth of InAs/GaAs and InAs/InGaAs/GaAs quantum dots (QDs) by metalorganic chemical vapor deposition (MOCVD). High density, defect-free InAs/GaAs quantum dots can only be grown in a narrow growth parameter window. The optimum thickness range of ∼ 1.65 monolayers (MLs) has to obeyed within ± 10% in order to obtain defect-free high density (1011 cm−2) QDs. During the growth interruption after the InAs deposition, the AsH3 flux also has to be switched off in order to avoid the formation of incoherent clusters. Under optimized conditions, high quality QD stacks with various separation layer thickness have been obtained. A reduction of the inhomogeneous broadening and an increase in efficiency of the room temperature luminescence is observed when the QDs are covered with a thin ternary In0.3 Ga0.7 As layer before the deposition of the GaAs cap layer.