Enhanced Nucleation and Enrichment of Strained-Alloy Quantum Dots

An epitaxial strained layer is metastable against nucleation of three-dimensional ``islands.'' For an alloy, I show that these islands nucleate at a substantially different composition than the alloy layer. This stress-induced segregation drastically increases the nucleation rate. For planar-layer electronic devices, these effects exacerbate the roughening problem. However, the same effects enhance the promise of ``self-assembled quantum dots.'' Possible ``self-capping'' of quantum dots is also discussed.