Surface-Tension-Driven Flow in Crystal Growth Melts

Abstract

Convection is an important parameter in crystal growth from the melt. A driving force for convection besides buoyancy, crystal rotation and crucible rotation, is the surface-tension gradient due to temperature or concentration gradients in the free melt surface. This article points out that in the various melt-growth techniques with free melt surface, e.g. the floating-zone technique, the Czochralski technique and the open-boat zoning, surface-tension-driven flow is likely to occur and to influence the growth. Surface-tension-driven flow is especially important in small melt volumes, near the free surface of larger volumes, or under conditions of weightlessness (e.g. in Spacelab). Under the large temperature gradients encountered in crystal growth, surface-tension-driven flow can become time dependent. Numerical studies, experiments on surface-tension-driven flow, and observations in real growth systems are reviewed.KeywordsFree SurfaceNormal GravityMarangoni NumberThermocapillary ConvectionFree Liquid SurfaceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.