Growth and properties of mosaic single crystals for -ray lens application

Bulk crystals of Ge 1 - x Si x solid solutions grown by modified Czochralski (CZ) technique were used for the production of the diffraction optics elements of the high-energy γ -ray telescope. The mosaic crystals were grown to improve the diffraction efficiency of the crystal lens. For developing growth methods for such crystals, the shape of the growth interface, the striation pattern of the distribution of the components and the mosaic structure must be known. Applying the lateral photovoltage scanning (LPS) method and optical microscopy their mosaic structure and shapes of the growth interface have been determined. In this paper, the first attempt was made to find the correlation between crystal structure, mosaicity and diffraction efficiency of Ge 1 - x Si x -based γ -ray optical elements.