Severe macro segregat ion tends to develop along Ga1-xInxSb alloy crystals grown by the conventional Czochralski process. Failure to eliminate macrosegregation by floating-crucible Czochralski has been attributed to InSb back diffusion from the floating crucible. In the present study Ga1-xInxSb crystals were grown from the growth melt in a floating crucible having a unique bottom tube that was wide to let the replenishing melt in the outer crucible pass through easily but long to suppress back diffusion. Ga1-xInxSb crystals with a uniform composition of 1 mol% InSb were grown as targeted. However, crystals of about 2mol% InSb were grown when 4rnol% InSb was targeted. By using Bi1-xSbx as a model material, it was found that hydrodynamic instability caused the problem-the denser growth melt mixed with the lighter replenishing melt during or even before crystal growth. A new double-crucible Czochralski process was thus developed, with an upper chamber for the growth melt and a lower chamber for the replenishing melt. The slightly higher gas pressure in the lower chamber caused replenishing through a long capillary tube that suppressed mixing between the melts. Single crystals of Ga1-xInxSb were grown with uniform compositions up to 4.5 mol% InSb. (c) 2007 Elsevier B.V. All rights reserved.