Formation and stability of II-VI self-assembled quantum dots revealed by in situ atomic force microscopy

A study on self-assembled CdSe quantum dots (QDs) on ZnSe is reported. The use of tin in situ ultra-high vacuum atomic force microscope (UHV-AFM) prov ides the morphological evidence for the thermally activated reorganization of an initially two-dimensional CdSe film into an array of QDs. The QDs have heights between 1.5 and 3.5 nm and lateral diameters smaller t han 10 nm. UHV-AFM images do not yield any evidence for Ostwald ripening. W e assign the ultra-high stability to the existence of a kinetic barrier pro hibiting the heterosystem to pass from the metastable QD state into the the rmodynamic equilibrium. (C) 2000 Elsevier Science B.V. All rights reserved.