Properties of self-organized CdSe quantum dots on an atomically flat (111)A ZnSe surface

The migration enhanced formation of self-organized CdSe quantum dots (SQD) on ZnSe employing atomic layer epitaxy (ALE) has been investigated. We used the (111)A surface which can be prepared atomically flat when the buffer layer thickness does not exceed 30 nm. The (111)A surface corresponds to the lowest energy surface with only one bond per surface atom. This together with reduced sticking coefficients leads to an enhanced surface migration of adatoms. In such a case the dot size and dot density should solely be determined by the average strain caused by the lattice mismatch in the system. We observe the formation of very reproducible SQDs (base diameter 28 +/- 4 nm, height 9 +/- 1 nm) already at a total deposition of CdSe well below 1 monolayer coverage. The density of the dots increases linear with the total amount of CdSe deposited. Alloying in the dots as a means of further strain reduction has to be considered. (C) 1998 Elsevier Science B.V. All rights reserved.