A series of Ge quantum dot superlattices were prepared to study the relationship of the dot morphology evolution with the number of layers. Strain relaxation was observed in thicker films and the dots transited from broad size distribution to size equalization and eventually to broad size distribution again as a result of the generation of threading dislocations in the quantum dot superlattice films. (C) 2004 Elsevier B.V. All rights reserved.