X-ray interference topography investigation of Si/GexSi1-x/Si(001) heterosystem

In x-ray topographs of Si/GexSi1-x/Si(001) heterosystems, the intensity variations, which are associated with inhomogeneous GeSi thickness, are observed. The layers of GeSi and Si were grown by molecular beam epitaxy. The growth conditions preserving the pseudomorphic state of the intermediate SiGe layer from misfit dislocation appearance were kept. The topographs were recorded using a spherically bent monochromator as well as a flat one. The observed contrast peculiarities are established to be Moire (translation fault) fringes. The displacement of interference fringes due to the crystal angular position variation is observed. For Pendelloesung maxima, the dependence of their angular positions on nondiffracted layer thickness is established. The image simulated in the framework of semikinematical approach demonstrates the main contrast peculiarities observed in the topograph