Interfaces and Transport Processes in Floating-Zone Crystal Growth

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The floating-zone process is an important method for growing single crystals of electronic, optical and high-Tc oxide superconducting materials. The shape of the melt/gas interface, i.e., the free surface of the melt zone, can significantly affect zone stability, which is critical to the successful operation of the process. The shape of the melt/crystal interface, as well as the solute and temperature distributions in the growing crystal, can significantly affect the crystal quality. These interface shapes and distributions are governed by transport processes such as heat transfer, mass transfer and fluid flow during crystal growth. In this project, analysis of the interfacial stability problem will be undertaken simultaneously with the study of heat and mass transport during crystal growth. It is expected that this integrated approach will contribute to the manufacture of larger single crystals and of purer and larger samples in zone refining. The research consists of three parts: 1. crystal growth and zone-stability improvement, 2. flow observation and segregation analysis, and 3. computer simulation. The study is unique in that the interaction between convection in the melt zone and the shapes of the melt/solid interfaces will be clearly demonstrated through direct observations of a transparent melt zone during actual crystal simulation.