Atomic ordering in self-assembled Ge:Si(001) islands observed by X-ray   scattering
  X-ray diffuse scattering in the vicinity of a basis-forbidden (200) Bragg reflection was measured for a sample with uncapped self-assembled Ge islands epitaxially grown on Si(001). Our results provide evidence of atomically ordered SiGe domains in both islands and wetting layer. The modeling of x-ray profiles reveals the presence of antiphase boundaries separating the ordered domains in a limited region of the islands where the stoichiometry is close to Si0.5Ge0.5. 
A. Malachias, T. U. Schulli, G. Medeiros-Ribeiro, M. Stoffel, O. G.   Schmidt, T. H. Metzger and R. Magalhaes-Paniago