Density of volume defects due to foreign particle inclusions in Czochralski= grown InSb crystals is 102-10~/cm a as detected by x-ray topography. The larger ones of these inclusions are frequently sources of dislocations. Dislocations in Czochralski-grown crystals are randomly oriented and curvilinear. InSb crystals prepared in space by partial remelting of Czochralski=grown seeds and regrowth after a 1 hr thermal soak period are markedly dii~erent. The density of inclusions is greatly reduced since foreign particles are accumulated during soak at the remelt boundary and at the melt surface. Dislocations originating from particles at the seed boundary are the cause of a sudden increase of dislocation density in the first portion of regrown material. Rectilinear dislocations (pure edge and 60 ~ type) are observed rather exclusively in the bulk of space-grown crystals. Since larger inclusions are.absent, few defects are generated, and the density of dislocations decreases along the axis of the samples due to outgrowing of rectilinear dislocations that are inclined to the growth axis. Increasing radial thermal gradients causes an increase of dislocation density in the crystal section solidified last. Generation and multiplication of dislocations due to radial thermal gradients become appreciable at gradients of about 10~176 ~Present address: Deutsche Forschungs-und Versuchsanstalt ffir Luft-und Raumfahrt,
A system of on‐facet and off‐facet striations was observed in selenium‐doped (1019/cm3)
normalInSb
that was prepared at g‐levels of 10−4–10−6 during Skylab mission SL‐4. The off‐facet striations could not be explained in terms of existing theory. A new concept is derived that considers the decrease of liquidus temperature in the initial transient region due to buildup of a diffusion layer. This model not only explains off‐facet striations in space‐grown
normalInSb
, but may also be the basis of certain nonrotational striations that are observed in crystals processed on the ground.
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