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.