Dresden 2020 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 17: Microstructure, Real Structure and Crystal Defects
KFM 17.8: Talk
Friday, March 20, 2020, 12:10–12:30, TOE 317
Investigation of the real structure by means of unconventional methods of the analytical electron microscopy — •Enrico Langer — Technische Universität Dresden, Institut für Halbleiter- und Mikrosysteme, 01062 Dresden, Germany
The primary beam of a scanning electron microscope generates a local X-ray source in the investigated sample, which besides the standard application for the energy dispersive X-ray spectroscopy leads in crystalline volumes directly to lattice source X-ray interferences (Kossel technique). A further possibility consists in a focus of electrons on thin metallic foils (e.g. Fe, Ti) close to the sample surface, which is suited for the generation of a X-ray source in transmission, whereby a tube shields from the bremsstrahlung. Pseudo-Kossel interferences emerge from the diffraction of these divergent X-rays at mono- and polycrystalline material. Beside the X-ray topography this is another method for the mapping and characterization of crystal defects. However, the influence of crystal lattice defects on pseudo-Kossel X-ray interferences was only partly investigated. This work should contribute to a better understanding. The basic investigations range from the real structure characterization of intermetallic alloys to semiconductor materials, such as silicon and GaAs. The deviations from the ideal pseudo-Kossel reflection show the fault of the crystal lattice. These will be assigned to a local section of the original curve on the crystal surface by simulation of complex curves of the 4th order using the further developed program KOPSKO1. Especially reflections ruptures can be assigned to the mosaic structure and sub-grains resp., small angle tilt or twist grain boundaries and can be measured with high accuracy. Curve sections with reflection broadening correspond to a local increase of the dislocation density, which were for example found near to grain boundaries in a Fe-Al alloy. Smallest local variations of the lattice constants lead to changes in the position perpendicular to the pseudo-Kossel curve. Even at single-crystals much more complicated regular line structures can be observed, but the formation of models is still not finished.
1 E. Langer, R. Kurt, S. Däbritz, Cryst. Res. Technol. 34 (1999) 801.