Density and size control of self-assembled InAs quantum dots: preparation of very low-density dots by post-annealing

A systematic study has been performed on the morphology of self-assembled InAs quantum dots (QDs) grown by molecular beam epitaxy on (0 0 1) GaAs surfaces using atomic force microscopy while varying the growth conditions, It is shown that the size and density of theses QDs can be controlled by the precise adjustment of growth temperatures and the amount of deposited InAs and also by post-growth annealing. One can now form QDs that are between 20 and 60 nm in diameter and between low 10(8) and mid 10(11) cm in density. Very low-density QDs prepared by post-annealing are particularly suitable for single QD studies. (C) 2002 Elsevier Science B.V. All rights reserved.