Published online by Cambridge University Press: 26 February 2011
High resolution electron microscopy is used to probe the atomic scale structure of interfaces and defects in the GexSi1−x/Si system. By careful quantification of lattice images, it is shown that molecular beam epitaxy may be used to grow GexSi1−x/Si (100) and (111) interfaces which are sharp on the scale of the unit cell and flat to within a few atomic planes when about 5000 Å2 of the interface are sampled. Interfacial quality is retained in single and multiple quantum well structures. Conditions for superlattice stability against misfit dislocations are discussed. It is shown that GexSi1−x/Si interfaces produced by molecular beam epitaxy at 550°C can exist in a metastable state which relaxes upon thermal annealing.