Dislocation-free silicon crystals with a large diameter and with the growth axis [001], which were grown by the Czochralski method in the vacancy mode, have been investigated by the section topography method. The oxygen content was 7x10~(17) cm~(-3). Specimens were subjected to the heat treatment in a neutral atmosphere. Macrodefects with sizes to 1 cm manifesting on the image as the disturbance of the dynamical interference pattern of a perfect crystal have been revealed on experimental topograms. These defects have no kinematical image and are not registered by the methods of projection topography and two-crystal spectrometer. The observed bulk macrodefects are the regions having the refraction coefficient different from the other part of the specimen and represent apparently a stable fluctuation of a microdefect concentration.
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