Te distribution in space grown GaSb

Inhomogeneity of a space grown crystal of Te-doped GaSb has been studied by the quantitative plane wave X-ray topography. The crystal is free of stria tions, whereas Te distribution over its cross section is noticeably nonunif orm. A region formed by the advancement of a facet, which was present at th e growth front, is revealed. This region is enriched with Te and contains s everal striations, at one of which a twin originates. Possible reasons for a nonuniform Te incorporation, growth-front faceting, and twinning are disc ussed. The conditions for growing high-quality crystals by the Bridgman met hod in space are suggested. These are (1) a reasonably small clearance betw een the growing crystal and the ampoule wall and (2) no growth-front faceti ng. (C) 2002 Elsevier Science B.V. All rights reserved.