Hierarchical self-assembly of epitaxial semiconductor nanostructures

We describe a new route to hierarchical assembly of semiconductor nanostructures, employing guided organization of self-assembling epitaxial quantum dot molecules in the GexSi1-x/Si(100) system. The quantum dot molecule comprises a shallow strain relieving pit, defined by {105} facets, and bounded by 4-fold {105}-faceted islands. Through topographic "forcing functions" fabricated on the substrate surface, the quantum dot molecules may be organized into arrays, enabling hierarchical structures spanning length scales from tens of nanometers; to macroscopic dimensions.