Self-ordering of quantum-wire superlattices on V-grooved substrates

A mechanism of self-ordering of quantum-wire superlattices via growth on nonplanar substrates is described. Alternate deposition of thin layers characterized by a longer and a shorter diffusion length of adatoms on a self-limiting V groove yields an exact compensation of the increase and decrease in the surface curvature. As a result, a self-limiting surface profile develops, which gives rise to a vertically stacked superlattice (SL) of crescent-shaped quantum wires (QWR’s). The structure of such SL’s is accurately modeled using the self-limiting growth characteristics of thick layers of the barrier and well materials. A systematic difference, found between the average composition of these QWR SL’s and the corresponding alloys, is interpreted in terms of the role of the entropy of mixing in the self-limiting growth process.