Method and apparatus for producing a dislocation-free crystalline sheet

Abstract

A dislocation-free sheet may be formed from a melt. A sheet of material with a first width is formed on a melt of the material using a cooling plate. This sheet has dislocations. The sheet is transported with respect to the cooling plate and the dislocations migrate to an edge of the sheet. The first width of the sheet is increased to a second width by the cooling plate. The sheet does not have dislocations at the second width. The cooling plate may have a shape with two different widths in one instance. The cooling plate may have segments that operate at different temperatures to increase the width of the sheet in another instance. The sheet may be pulled or flowed with respect to the cooling plate.

1 . An apparatus for forming a sheet comprising:
 a vessel defining a channel configured to hold a melt of a material;   a cooling plate above said melt, said cooling plate having a first segment and a plurality of second segments, said plurality of second segments configured to independently control temperature compared to said first segment.   
     
     
         2 . The apparatus of  claim 1 , wherein said melt is configured to flow from a first point to a second point of said channel. 
     
     
         3 . The apparatus of  claim 1 , wherein said material comprises silicon or silicon and germanium. 
     
     
         4 . The apparatus of  claim 1 , further comprising a third segment, said third segment configured to independently control temperature compared to said first segment.