Molecular beam epitaxy of silicon-germanium nanostructures

The current status of the research in the field of synthesis and applicatio n of silicon and germanium-based nanostructures formed by the process of 3D island self-organization is reviewed in the present paper. There was an ob vious conclusion that elastic deformations in epitaxial films and 3D island s are the key factor which is not only the reason of the transition from pl anar to Stranski-Krastanow mechanism of growth, but also influences the nex t stages of islands evolution including their shape, size and spatial distr ibutions. There are many cases when this factor makes crucial changes to th e classical set of phase-formation mechanisms right up to an equilibrium co existence of islands on a surface. Various types of ordering were classifie d in the nanocluster systems under consideration: in cluster shape, in its size, in the distance between nearest islands, as well as ordering through vertical, i.e. in successively growing multilayer structures containing qua ntum dots. The results of recent original investigations of electrical and optical properties of self-assembled arrays of Ge quantum dots are presente d. (C) 2000 Elsevier Science S.A. All rights reserved.