Rocking curves in silicon implanted with 4.8 MeV α‐particles with interference maxima of increasing periodicity are simulated numerically using the Takagi‐Taupin theory for different approximations of lattice parameter profiles. The best correspondence with experimental curves is obtained for the profiles computed using the Monte‐Carlo method from the Biersack‐Ziegler theory, or approximated by a fragment of a hyperbola. It is stated that increasing periodicity of interference maxima occurs when the lattice parameter gradient gradually increases towards the destroyed layer. By simultaneous consideration of the bicrystal model this fact is interpreted as due to the change in the width of the layer decomposing the wave fields for different angles of incidence. The reflection curves exhibit also the fast modulation unresolved in the convoluted and experimental curves. The actually revealed numerical program provides also a reasonable approximation of interference fringes in double‐crystal topographs, caused by the variation of implanted‐ion dose.

The perfection of YVO4 crystals, which are predicted to replace formerly used YAG garnets due to higher quantum efficiency and lower excitation level, was studied. The investigations of Czochralski grown undoped YVO 4 single crystals were performed mainly by means of X-ray topographic methods. Both synchrotron and conventional X-ray sources were used. The study revealed relatively high density of weak point-like contrasts which can be most probably interpreted as dislocation outcrops. In regions of the crystal close to its boundary we observed glide bands. It was also found that in some regions the dislocations form local subgrain boundaries. The white beam back reflection and monochromatic beam topography allowed to evaluate a local misorientation which not exceeded several angular minutes. No segregation fringes were observed proving a good homogeneity of chemical composition.

Back-reflection section topography using white-beam synchrotron radiation has been applied for the investigation of silicon implanted with 1 and 1.6 MeV protons and 4.8 MeV c~ particles. The beam width was limited to 5 lam, and a series of spots in the vicinity of a centrally adjusted reflection were indexed and analysed. The backreflection section pattern of implanted crystals usually exhibits fringes corresponding to the reflection from the surface and a series of fringes corresponding to the rear region of the shot-through layer, the destroyed layer and the bulk. The patterns were used for direct evaluation of ion ranges and thicknesses of the shot-through layer. The overall characteristics of the obtained patterns were successfully reproduced in simulations based on numerical integration of the Takagi-Taupin equations. The agreement between the simulation and experiment proves that the lattice-parameter depth-distribution profiles can be assumed to be proportional to interstitial-vacancy distributions obtained using the Monte Carlo method from the Biersack-Ziegler theory. The simulation also reproduced interference tails observed in some section patterns. It was found that these tails are caused by the ion-dose change along the beam and they were probably formed due to the interference between the radiation reflected from the bulk and those rays reflected by the rear region of the shot-through layer.

The numerical integration of Takagi-Taupin equations was used for the simulation of double-crystal topographic images of threading dislocations, misfit dislocation crossings and point-like precipitates in silicon and gallium arsenide. The simulations took account of lattice parameter profiles and the finite divergence of the beam. It was found that the images of dislocations, especially those outcropping on the surface, are dominated by a dilation-orientation contrast. Stronger interference effects were present in the images of point-like defects. A similarity was observed between the images of threading dislocations computed for equivalent positions in the layer and substrate maxima. A reasonable correspondence between simulated and experimental images was confirmed in several cases.

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