FLUESSIGKEITSGEFAESS UND VERFAHREN ZU DESSEN HERSTELLUNG

Apparatus is described for controlling the crystallization of semi-conductor materials involving the use of a shape forming member or die having a passage within which the crystallization interface is located and kept during the growth process. Techniques are disclosed for reducing the angle of contact measured outside the liquid between the melt liquid within the passage and the material forming the wall of the passage. The basic technique involves the formation of a rough surface typically by machining ridges in the surface of the passage. Formulae are derived for determining the maximum elemental spacing between ridges and the minimum depth of the grooves therebetween so that a liquid melt surface is supported wholly by surface tension forces between the ridges. Examples of spacing and depth parameters for various melt/die material combinations are given. Differential elemental spacing from one region of a die surface to another is employed so as to reduce the surface working requirements to the minimum. Composite dies in which a fluid under pressure additionally supports the melt liquid surface are also described.