Numerical simulation of Bragg-case section topographic images of dislocations in silicon

Synchrotron white beam with a wavefront limited by a 5 mu m slit was used f or obtaining the Bragg-case section patterns in silicon substrates and epit axial layers. The section images contained various interference fringes, su ch as the Uragami fringes and fringes caused by crystal curvature. The syst em of fringes connected with individual defects was also observed. The experimental images were compared with simulated theoretical images obt ained by numerical integration of the Takagi-Taupin equations. A reasonably good correspondence was obtained for dislocations inclined to the surface and misfit dislocations. The elements of the image were analysed using the visualization of \ D-h\(2) and \ D-o\(2) intensities in the plane of diffra ction, where an additional amount of transmitted wave intensity indicated t he decomposition of wavefields or the reflection of the redirected waves fr om the surfaces. Comparative studies of simulated precipitation images and modification of dislocation images caused by curvature and by the diffusion of an epitaxial junction were also performed.