The growth of vertically aligned self-assembled PbSe/Pb1-xEuxTe quantum-dot superlattices is found to result in a pronounced hexagonal lateral ordering tendency accompanied by a narrowing of the size distribution. In addition, the lateral dot separations and dot densities become tunable by changes in the spacer thickness with an almost twofold density increase for spacer thicknesses increasing from 100 to 275Å. Similar marked changes are also found for PbSe dot sizes and shapes. This could provide additional means for the tuning of the optical and electronic properties of the dots. © 2002 American Institute of Physics.