Self-assembled PbSe quantum dots on PbTe quasisubstrates, where the quasisubstrate layer is grown on Si(111), show a size distribution as low as 2%, below any other reported size distribution. The result is explained by nonoverlapping diffusion radii for most of the dots and their nucleation occurring mainly at defects (glide steps of the quasisubstrate), conditions which are not met by self-assembled quantum-dot structures in other material systems.

• Received 17 September 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.026104