X-ray Diffraction Topography - Investigation of Single Crystals Grown by the Czochralski Method

X-ray diffraction topography is one of basic diagnostics tools serving for visualisation of single crystal lattice defects. Defects of various kinds can be observed. The present study is a review of topographic results obtained in the X-ray laboratory of the Institute of Experimental Physics, University of Warsaw, for three families of single crystals grown by the Czochralski method: (i) silicon (Si) and $Si_{1-x}Ge_{x}$, (ii) selected binary REVO_4 oxides and (iii) selected ternary $ABCO_4$ oxides. The effect of chemical composition, growth conditions and post growth thermal annealing on the defect appearing in crystals is discussed. Various defects are revealed: the growth dislocations (some early Si crystals), the composition-gradient-induced lattice deformation $(Si_{1-x}Ge_{x}$, solid solutions $Ca_{x}Sr_{1-x}NdAlO_4)$, defects generated in Si after the post growth thermal processes, oriented elongated rod-like macro-defects tending to form networks within the crystal core, cellular structure in the outer shell $(SrLaGaO_4)$, and variously developed block structure (in selected binary $\text{REVO}_4$ crystals)

Interference Fringes in the Plane Wave Topographic Images of Growth Bands in Si:Ge

An Si:Ge crystal with approximately 3% of germanium was studied with strongly collimated short-wavelength monochromatic synchrotron beam (beamline E2 at HASYLAB). The topographs obtained in the asymmetric 224 reflection revealed the presence of interference fringes related to growth bands caused by segregation of germanium. The fringes, observed for the first time, were strongly dependent on the angular setting and it was possible to distinguish at least three systems of fringes. A number of features of the existing strain field, which may be important for the formation of the fringes, was determined using other topographic methods, especially the Bragg-case section topography

Conventional and synchrotron X-ray topography of defects in core region of SrLaGaO4SrLaGaO_4

$SrLaGaO_4$ single crystals are perspective substrate materials for high temperature superconductors thin films, elements of thermal radiation receivers and other electronic devices. The defect structure of the Czochralski grown $SrLaGaO_4$ crystal was investigated by means of X-ray topography exploring both conventional and synchrotron sources. The crystal lattice defects in the core region of the crystal were investigated. The regular network of defects arranged in rows only in ⟨100⟩ direction was observed. Owing to high resolution of synchrotron radiation white beam back reflection topographs one can distinguish individual spots forming the lines of the rows. It can be supposed that these elongated rod-like volume defects are located in 100 lattice planes forming a kind of walls. They are built approximately of the same phase as crystal but crystallize at a different moment than a rest of the crystal due to the constitutional supercooling