We have developed a zone growth method of producing an InxGa1-xAs single crystal with uniform InAs composition in the direction of the growth. The seed used for this method of zone growth is an InGaAs single crystal grown on a GaAs seed using the vertical gradient freeze (VGF) method. The source for the zone growth method is an InGaAs ternary alloy produced by quenching an InGaAs melt with an InAs composition of 0.3. The convex solid-liquid interface toward the melt is necessary for growing a long InGaAs zone single crystal. We examined ways to control the shape of the solid-liquid interface for the InGaAs zone crystal. We found that: (1) growing an InGaAs crystal in the furnace region, where the temperature gradient in the growth direction changes abruptly, is effective in forming the convex solid-liquid interface toward the melt and (2) lengthening the heat sink attached to a seed increases the efficiency of heat discharge through the crystal and the solid-liquid interface becomes convex. The InGaAs zone crystal having a uniform InAs composition region of 0.3 was a perfect single crystal and was 17 mm long, which is more than twice the length of zone single crystals grown previously. The orientation of the crystal growth was (0 0 1), and the crystal diameter was 15 mm. (C) 2002 Elsevier Science B.V. All rights reserved.