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A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga,,IqSb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt.The homogeneous Ga,-,IqSb single crystals were grown successfully by a pressure-differentia1 technique. By separating a quartz tube into an upper chamber for .. 11crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber.The method was first tested with a low temperature alloy Bil,Sb,. Single crystals of GaI-,In$b were grown with uniform compositions up to nearly 5 mole% InSb.... 111 ACKNOWLEDGMENTSThe author wishes to express his sincere appreciation to Professor Sindo Kou, his advisor, for his guidance and enthusiasm.