Tantalum based crucible

Abstract

A crucible is provided that is thermally stable at high temperatures and is suitable for use in the growth of large, bulk AlN, Al x Ga 1-x N or other nitride single crystals. The crucible is comprised of specially treated tantalum. During the initial treatment, the walls of the crucible are carburized, thus achieving a crucible that can be subjected to high temperatures without deformation. Once the carburization of the tantalum is complete, the crucible undergoes further treatment to protect the surfaces that are expected to come into contact with nitride vapors during crystal growth with a layer of TaN. If the crucible is to be used with a graphite furnace, only the inner surfaces of the crucible are converted to TaN, thus keeping TaC surfaces adjacent to the graphite furnace elements. If the crucible is to be used with a non-graphite furnace, both the inner and outer surfaces of the crucible are converted to TaN.

1 . A crucible fabricated from tantalum, comprising: 
 a plurality of interior surfaces;    a plurality of exterior surfaces;    a tantalum carbide layer formed on said plurality of interior surfaces and said plurality of exterior surfaces; and    a tantalum nitride layer formed on said tantalum carbide layer formed on said plurality of interior surfaces.    
   
   
       2 . The crucible of  claim 1 , wherein a carbon concentration in said tantalum carbide layer is greater than 0.02 grams per square centimeter.  
   
   
       3 . The crucible of  claim 1 , wherein said tantalum nitride layer is approximately 1.5 millimeters thick.  
   
   
       4 . A crucible fabricated from tantalum, comprising: 
 a plurality of interior surfaces;    a plurality of exterior surfaces;    a tantalum carbide layer formed on said plurality of interior surfaces and said plurality of exterior surfaces; and    a tantalum nitride layer formed on said tantalum carbide layer formed on said plurality of interior surfaces and said plurality of exterior surfaces.    
   
   
       5 . The crucible of  claim 4 , wherein a carbon concentration in said tantalum carbide layer is greater than 0.02 grams per square centimeter.  
   
   
       6 . The crucible of  claim 4 , wherein said tantalum nitride layer is approximately 1.5 millimeters thick.