Structural and magnetic properties in Mn-doped GaN grown by metal organic chemical vapor deposition Appl. Phys. Lett. 92, 152116 (2008); 10.1063/1.2909545 Anomalous magnetic properties of the ferrimagnetic semiconductor on Ga-doped sulphur spinel

A variety of oxygen-related micro-defects (spherical and octahedral precipitates, their agglomerations, dislocations and dislocation loops) with dimensions in the range 0.1-100 mu m were revealed using X-ray topography and transmission electron microscopy after two-step annealing of Czochralski-grown silicon. The defects are distributed in a non-uniform way across the samples with the gradient of their density normal to the crystal surface.

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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.