X-ray spherical wave scattering patterns of the epitaxial Si/GeSi/Si (001) heterosystem

The interference effects of x-ray diffraction topography in the Si/GeSi/Si (001) heterosystem have been investigated. This heterosystem is a film interferometer in which the GeSi solid solution layer of variable thickness serves as a separating gap. A topograph obtained for a 004 reflection (CuK _α radiation) using a spherically bent monochromator demonstrates both maxima of the pendulum solution observed for the case of a thin crystal (1) and interference fringes due to the variable thickness of the separation layer (2). The correlation of effects (1) and (2) with the successive extinction effect of interference maxima on the slope of the diffraction reflection curve is shown by the calculated topographs obtained for the different ranges of the angle of radiation incidence θ (200 and 1400″). The possibility of precisely determining the thickness of the crystal separation layer of an interferometer based on the indicated effect is demonstrated.