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 gro wth parameter window. The optimum thickness range of similar to 1.65 m onolayers (MLs) has to obeyed within +/-10% in order to obtain defect- free high density (10(11) cm(-2)) QDs. During the growth interruption after the InAs deposition, the AsH3 flux also has to be switched off i n order to avoid the formation of incoherent clusters. Under optimized conditions, high quality QD stacks with various separation layer thic kness 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 In0.3Ga0.7As lay er before the deposition of the GaAs cap layer. (C) 1998 Elsevier Scie nce B.V.