Inhomogeneities due to thermocapillary flow in floating zone melting

Abstract

Theoretical calculations have shown that radial inhomogeneities are produced by thermocapillary flow at low driving forces unless the zone travel rate is very low or the distribution coefficient is near unity. At intermediate driving forces the flow is probably oscillatory, which would produce striations. At large driving forces the flow is turbulent. For floating zone melting of silicon, the thermocapillary flow is not appreciably influenced by buoyancy at earth's gravity or by motion of the zone at the usual rates. Thermocapillary flow is probably also important in Czochralski growth of silicon and in floating zone melting with induction heating, unless effective heat shields are employed. © 1975.