procedures to change the crystalline structure of a rohrfoermigen ausgangskristall and / or to change the concentration of the rohrfoermigen ausgangskristall fremdstoffes contained

摘要

1,239,515. Zone-melting. SIEMENS A.G. 29 Oct., 1969 [30 Oct., 1968], No. 52888/69. Heading B1S. A silicon tube is subjected to floating zonemelting using a horizontal annular heater and a seed which is in the form of (a) a narrow rod attached to one end of the silicon tube, the tube and rod being inclined to the vertical, or (b) a narrow tube attached to a tapered end portion of the silicon tube, the tubes being vertical and rotated. In case (a) an elliptical heater is situated inside the silicon tube (as shown in Fig. 3), outside (Fig. 1) or both, e.g. inner and outer induction coils in series opposition (Fig. 5a). In case (b) a circular heater is situated outside the silicon tube (as shown in Fig. 6). Heating may be by radiation, induction, or electron or plasma discharge. The silicon tube may be compressed or stretched during treatment. Pre- or postheating may also be effected.