Growth of homogeneous single crystals of GeSi solid solutions using a Ge seed by the modified Bridgman method

A modified technique for the growth of homogeneous Ge-rich GeSi single crystals is developed on the basis of the vertical Bridgman method using a Ge seed and a Si source rod. Single crystals were grown in two stages. In the first stage, a Si source rod was partially immersed in the Ge melt above the seed. A gradual increase in the Si content in the melt leads to constitutional supercooling at the crystallization front and to the growth of an inhomogeneous GeSi buffer single crystal. The first stage ends when the temperature at the crystallization front becomes equal to the liquidus temperature of the specified composition of the Ge-Si system. In the second stage, a homogeneous GeSi single crystal is grown while maintaining a constant growth temperature. The growth temperature is controlled by an appropriate balance between the pulling and feeding rates. Relations determining the optimal process parameters (the pulling and feeding rates and the temperature gradient at the crystallization front) for growing crystals of specified composition are obtained.