Device and process for producing a block of crystalline material

Abstract

A temperature gradient is established in a crystallization crucible by means of a heat source and a cooling system. The cooling system comprises a heat exchanger and an adjustable additional heat source. The cooling system is preferably formed by an induction coil cooled by a coolant liquid circulating in the induction coil and by an electrically conductive induction susceptor positioned between the crucible and induction coil. The fabrication process comprises heating the crucible via the top and controlling heat extraction from the crucible downwards by means of the heat exchanger and by means of regulation of the adjustable additional heat source.

1 . A device for the fabrication of a block of crystalline material by directional crystallization, the device comprising:
 heating means and cooling means arranged such as to establish a temperature gradient in a crystallization crucible,   wherein the cooling means are arranged under the bottom of the crystallization crucible so as to cover the bottom of the crystallization crucible and comprise:
 a heat exchanger and an adjustable additional heat source, 
 an induction coil cooled by a coolant liquid circulating in the induction coil and an electrically conducting induction susceptor positioned between the crystallization crucible and conduction coil. 
   
     
     
         2 . The device according to  claim 1 ,
 wherein the susceptor is made from a thermally conducting material that absorbs infrared radiation.   
     
     
         3 . The device according to  claim 2 ,
 wherein the susceptor is made from one of graphite and silicon carbide.   
     
     
         4 . The device according to  claim 1 , wherein the susceptor forms a support for the crystallization crucible. 
     
     
         5 . The device according to  claim 1 , further comprising silica plates arranged around the induction coil. 
     
     
         6 . The device according to  claim 1 , wherein the crystallization crucible comprises a transparent bottom made from impurity-free amorphous silica. 
     
     
         7 . The device according to  claim 1 , further comprising a removable felt positioned above the heat exchanger.