Apparatus and method for managing a temperature profile using reflective energy in a thermal decomposition reactor

Abstract

Embodiments of a reflective surface and a reflector comprising a reflective surface for use in a thermal decomposition reactor are disclosed. Methods for using the reflective surface, or reflector comprising the reflective surface, to manage a temperature profile in a silicon rod grown in the thermal decomposition reactor are also disclosed. The reflective surface is configured to receive radiant heat energy emitted from an energy emitting region of an elongated polysilicon body grown during chemical vapor deposition onto a silicon filament and reflect at least a portion of the received radiant heat energy to a reflected energy receiving region of the elongated polysilicon body or to a reflected energy receiving region of a second elongated polysilicon body, to thereby add radiant heat energy to the reflected energy receiving region.

We claim: 
     
         1 . A three-sided, frusto-pyramidal reflector comprising:
 an upper surface;   a lower surface; and   first, second, and third side surfaces, wherein the first side surface is a first concave reflective surface.   
     
     
         2 . The reflector of  claim 1 , wherein:
 the first concave reflective surface is in the shape of a portion of a paraboloid, a sphere, a tapered cylinder, or a cylinder, the cylinder having a longitudinal axis at an angle θ relative to vertical.   
     
     
         3 . The reflector of  claim 1 , wherein the first concave reflective surface has a focal length of 10-50 cm, providing an optical power from 20 to 100 m −1 . 
     
     
         4 . The reflector of  claim 1 , wherein the first concave reflective surface is in the shape of a portion of a paraboloid. 
     
     
         5 . The reflector of  claim 4 , wherein the paraboloid has a vertex, a focus point, and a paraboloid axis of symmetry offset from a midpoint of the first concave reflective surface. 
     
     
         6 . The reflector of  claim 5 , wherein the vertex is not a point on the first concave reflective surface. 
     
     
         7 . The reflector of  claim 1 , wherein the first concave reflective surface is configured to receive radiant heat energy and reflect at least a portion of the received radiant energy, wherein reflected radiant heat energy is directed at a three-dimensional surface, a two-dimensional area, a point, or a line on a receiving energy region of a body. 
     
     
         8 . The reflector of  claim 1 , wherein the first concave reflective surface is substantially smooth with any surface irregularities having an average amplitude of less than 3 mm. 
     
     
         9 . The reflector of  claim 1 , wherein the second side surface is a second concave reflective surface. 
     
     
         10 . The reflector of  claim 9 , wherein the second concave reflective surface is in the shape of a portion of a paraboloid, a sphere, a tapered cylinder, or a cylinder, the cylinder having a longitudinal axis at an angle θ relative to vertical. 
     
     
         11 . The reflector of  claim 9 , wherein the first and second concave reflective surfaces are mirror images of one another and have the same optical power. 
     
     
         12 . The reflector of  claim 9  wherein the first and second concave reflective surfaces have different configurations and do not have the same optical power. 
     
     
         13 . The reflector of  claim 1 , wherein:
 the lower surface of the reflector defines one or more depressions configured to receive one or more protrusions of a structure on which the reflector is positioned;   the third side surface is a rear surface, and the reflector further comprises a cavity defined by portions of the lower surface and the rear surface;   the upper surface of the reflector comprises one or more features to facilitate positioning, alignment, or positioning and alignment of the reflector; or   any combination thereof.   
     
     
         14 . The reflector of  claim 1 , wherein the lower surface of the reflector defines one or more depressions configured to receive one or more protrusions of a structure on which the reflector is positioned, and inner walls of the depressions include internal threads. 
     
     
         15 . The reflector of  claim 1 , wherein the lower surface has a triangular configuration with concave arc edges. 
     
     
         16 . The reflector of  claim 1 , wherein:
 the reflector is constructed of a material that does not evolve chemical species comprising Group III elements, Group V elements, metals, oxygen, or carbon during reactor operation.   the reflector is constructed of, or plated with, a material having an emissivity <0.5; or   a combination thereof.   
     
     
         17 . The reflector of  claim 1 , wherein the reflector is constructed of, or plated with, nickel, a nickel alloy, stainless steel, molybdenum, a molybdenum alloy, tungsten, a tungsten alloy, cobalt, a cobalt alloy, titanium, a titanium alloy, gold, a gold alloy, silver, a silver alloy, tantalum, or a tantalum alloy.