The coherent X-ray diffraction method was particularly attractive for understanding structures that could be represented as phase objects. Diffraction from a crystal acquires a phase whenever atoms were displaced from lattice sites, even by small fractions of an angstrom, so coherent X-ray diffraction measured around a Bragg peak was ideal for studying strain. Some success was had in using these coherent beams to study the strain field arising from individual misfit dislocations located at an interface between a GeSi thin film and its Si(001) substrate. The data were not inverted to images, but it was shown how the asymmetrical coherent X-ray diffraction patterns could be explained qualitatively by a model phase structure.

Coherent Diffraction Patterns of Individual Dislocation Strain Fields. I.K.Robinson, Y.Da, T.Spila, J.E.Greene: Journal of Physics D, 2005, 38[10A], A7-10