Self-organization of nanostructures in semiconductor heteroepitaxy

In semiconductor heteroepitaxy the growing film frequently undergoes a series of strain relief mechanisms that may include surface reconstruction, step bunching, faceting, and finally formation of misfit dislocations. Under certain conditions, these mechanisms and their interplay result in self-organized nanostructure arrays with a high degree of uniformity. Using atomic force microscopy and X-ray diffraction investigations, the following mechanisms are analyzed in the model system of Si1−xGex molecular beam epitaxy Si(0 0 1): 1. ion of ripple patterns by bunching of the preexisting steps on vicinal substrates, unch faceting on high miscut substrates, ated ripple propagation in heteroepitaxial superlattices, lay of three-dimensional island arrangement and step-bunched ripple patterns, lay of island arrangement and cross-hatched dislocation network, ion of three-dimensionally ordered island arrays in multilayer films. riving forces of these self-organization mechanisms—that are not restricted to a particular growth system—are discussed in the framework of continuum elasticity theory. Besides optoelectronic applications (not extensively considered here) a novel use of self-organized semiconductor nanostructures is proposed, namely the utilization as large-area templates to grow various materials on them. This is demonstrated for the case of magnetic thin films that can be nanostructured by this way.