How to control the self-organization of nanoparticles by bonded thin layers

The modulation of an elastic strain field due to a buried incoherent interface is analytically calculated for three different cases: a bonded layer with (1) a misfit, or (2) a miscut of (3) a twist. The interfacial dislocations induce a periodic strain field at the free surface, with a period Lambda. The energy modulation of the formation of an island on this strained surface, via the Stranski-Krastanov mechanism, is evaluated as a function of bonded layer thickness, h, and island misfit, f(2). For edge dislocations (misfit and miscut), the modulation decreases as h(-1) for h < Lambda and as h exp - Lambda for h > Lambda. It is shown that screw dislocations (twist) are, by two orders of magnitude, less effective than edge dislocations. The exact location of preferential nucleation of islands is calculated: they are not always nucleated on top of the exact position of the buried dislocations. Similarly, etching locations are predicted in each case. Few examples illustrate the different semiconductor materials on which self-organization of nanoparticles could be obtained. The main requirement for the experimental success is a good control of the miscut angle of both the substrate and the bonded layer. (C) 1999 Elsevier Science B.V. All rights reserved.