C-plane sapphire method and apparatus

Abstract

A method and apparatus for the production of C-plane single crystal sapphire is disclosed. The method and apparatus may use edge defined film-fed growth techniques for the production of single crystal material exhibiting low polycrystallinity and/or low dislocation density.

What is claimed is: 
     
         1 . (canceled) 
     
     
         2 . A single crystal growth apparatus, comprising:
 a die with a die opening;   a first region of the apparatus adjacent to the die opening, wherein the first region is configured to exhibit a first thermal gradient;   a second region of the apparatus configured to exhibit a second thermal gradient, wherein the first region is between the die and the second region; and   wherein the first thermal gradient is greater than the second thermal gradient.   
     
     
         3 . The apparatus of  claim 1 , wherein the first thermal gradient is at least twice the second thermal gradient. 
     
     
         4 . The apparatus of  claim 1 , wherein a heat shield is disposed adjacent to the first region. 
     
     
         5 . The apparatus of  claim 1 , wherein the second region of the apparatus does not include a heat shield. 
     
     
         6 . The apparatus of  claim 1 , further comprising a heater disposed to supply heat to the second region of the apparatus. 
     
     
         7 . The apparatus of  claim 1 , wherein the first region of the apparatus does not include a heater. 
     
     
         8 . The apparatus of  claim 1 , wherein the first thermal gradient extends along a path of crystal growth for a distance of at least 1 cm. 
     
     
         9 . The apparatus of  claim 1 , further comprising an enclosure disposed above the die, wherein the enclosure includes the second region of the apparatus. 
     
     
         10 . The apparatus of  claim 9 , wherein a bottom of the enclosure is adjacent to a top of the die. 
     
     
         11 . A single crystal growth apparatus, comprising:
 a die with a die opening;   a first region of the apparatus adjacent to the die opening;   an enclosure disposed above the die; and   a heater disposed above the first region, wherein an elevation of the heater is higher than an elevation of a bottom of the enclosure.   
     
     
         12 . The single crystal growth apparatus of  claim 11 , wherein the enclosure includes a second region of the apparatus, wherein the first region of the apparatus is between the die opening and the second region of the apparatus. 
     
     
         13 . The single crystal growth apparatus of  claim 12 , wherein:
 the first region is configured to exhibit a first thermal gradient;   the second region is configured to exhibit a second thermal gradient; and   the first thermal gradient is greater than the second thermal gradient.   
     
     
         14 . The single crystal growth apparatus of  claim 11 , further comprising a heat shield disposed adjacent to the die opening. 
     
     
         15 . The single crystal growth apparatus of  claim 14 , wherein the heat shield is a horizontal heat shield. 
     
     
         16 . The single crystal growth apparatus of  claim 14 , further comprising a vertically disposed insulation shield. 
     
     
         17 . The single crystal growth apparatus of  claim 16 , wherein the insulation shield is disposed outside of the heat shield. 
     
     
         18 . The single crystal growth apparatus of  claim 11 , wherein the heater is configured to apply heat to a second region of the apparatus, wherein the second region of the apparatus is above the first region of the apparatus. 
     
     
         19 . A single crystal growth apparatus, comprising:
 a crucible;   a first heater configured to heat the crucible;   a heat shield disposed above the crucible; and   a second heater configured to heat a region above the heat shield,   wherein the apparatus does not include a third heater between a top of the crucible and the heat shield.   
     
     
         20 . The single crystal growth apparatus of  claim 19 , further comprising an enclosure disposed above the crucible, the enclosure including the region. 
     
     
         21 . The single crystal growth apparatus of  claim 19 , further comprising an insulation shield, wherein the heat shield is disposed between the insulation shield and the enclosure.