Crucible rotation effect on crystallization rate behavior during CZ Si1-xGex growth has been numerically studied for several crystal positions of the growth, including the initial and final stages. It has been shown that the melt flow structures strongly differ at various crucible rotation rates and at decreasing the melt depth, which results in quite specific behavior of crystallization characteristics. The computations explained physical reasons of experimentally observed unstable crystal growth at the stage of upper cone formation. (c) 2005 Elsevier B.V. All rights reserved.