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It is shown through rigorous dynamical diffraction modeling that the ray tracing methods employed in kinematical diffraction analysis of strain become invalid for weakly deformed crystals that scatter in the dynamical limit. For an Si crystal illuminated by 12 keV X-rays, the kinematical formalisms should not be used if the strain gradient along the diffraction vector is smaller than 10−5 µm−1.

This work presents a set of equations that can be used to predict the dynamical diffraction profile from a non-transparent single crystal with a constant strain gradient examined in Bragg reflection geometry with a spherical incident X-ray beam. In agreement with previous work, the present analysis predicts two peaks: a primary diffraction peak, which would have still been observed in the absence of the strain gradient and which exits the specimen surface at the intersection point of the incident beam with the sample surface, and a secondary (mirage) peak, caused by the deflection of the wavefield within the material, which exits the specimen surface further from this intersection point. The integrated intensity of the mirage peak increases with increasing strain gradient, while its separation from the primary reflection peak decreases. The directions of the rays forming the mirage peak are parallel to those forming the primary diffraction peak. However, their spatial displacement might cause (fictitious) angular shifts in diffractometers equipped with area detectors or slit optics. The analysis results are compared with experimental data from an Si single-crystal strip bent in cantilever configuration, and the implications of the mirage peak for Laue analysis and high-precision diffraction measurements are discussed.

We have used scanning microdiffraction topography to determine the mismatch strains and local strain distributions in silicon-on-insulator substrates with overlying thin film stressor features. Analysis of the data using the edge-force model and the Ewald–von Laue dynamical diffraction theory shows the presence of an exponential strain gradient in the vicinity of the buried SiO2/Si-substrate interface. We show that, for simple geometries, it is possible to deduce the sign of the mismatch strain simply by inspecting the microdiffraction topograph.

We describe the evolution of the x-ray scattering pattern which forms on an area detector when a divergent, coherent nanobeam is diffracted from a perfect or weakly deformed single crystal. We show that the scattering can be considered as virtual diffraction from an angular aperture in reciprocal space; this is analogous to pinhole diffraction in real space. We define an angular Fresnel number, YA, which allows the categorization of the nanodiffraction image into near-field, intermediate-field, and far-field regimes. We provide equations for YA in simple geometries and show that dynamical scattering artifacts are eliminated through wave interference in the far-field image; this is the only regime where direct analysis of the charge coupled device image using geometrical formulae to transform distances to diffraction angles is possible.

Radiation induced structural damage is observed in silicon-on-insulator (SOI) and SiGe on SOI samples illuminated with monochromatic (11.2keV) x-ray microbeams approximately 250nm in diameter. The x-ray diffraction peaks from the irradiated layers irreversibly degrade with time, indicating permanent structural damage to the crystal lattice. The size of the damaged regions is almost an order of magnitude larger than the beam size. The magnitude of damage decreases as one moves away from the center of the illuminated volume. We discuss the threshold dosage required for damage initiation and possible mechanisms for the observed damage.