Synchrotron Diffraction topography in Studying of the Defect Structure in Crystals Grown by the Czochralski Method

The synchrotron diffraction topography had been widely used for investigation of the structural defects in crystals grown by the Czochralski method. Similarly as conventional diffraction topography, the synchrotron topography consists in recording with high spatial resolution of the beam formed by the Bragg reflection from the crystal. The advantages of synchrotron sources come from the possibilities of using the wavelength from a wide spectral range, improved high spatial resolution and collimation of the beam as well as from shortening the time necessary for the investigation. The synchrotron diffraction topography includes experimentally simpler white beam topography and more complicated monochromatic beam (multicrystal) topography, where the beam is formed by monochromators. In the case of Czochralski-grown crystals the synchrotron diffraction topography can be used for studying of the individual dislocations and their complexes such as glide bands or sub-grain boundaries, individual blocks, twinning, the domain structure and various segregation effects negatively affecting crystal properties. In addition, the topographical investigation can provide information concerning the reasons for the generation of defects, useful in the improving of the technology. In the present paper the possibilities of the synchrotron diffraction topography are discussed on the basis of several investigations of the Czochralski-grown oxide and semiconductor crystals, performed by the authors at HASYLAB. The majority of the results concern the oxide crystals grown at the Institute of Electronic Materials Technology, in particular garnets, orthovanadates, mixed calcium barium and strontium niobates as well as praseodymium lanthanum aluminates.