Method and apparatus for growth of multi-component single crystals

Abstract

A method and apparatus for growth of uniform multi-component single crystals is provided. The single crystal material has at least three elements and has a diameter of at least 50 mm, a dislocation density of less than 100 cm −2 and a radial compositional variation of less than 1%.

1 . A composition of matter comprising a single crystal material having at least three elements and comprising a diameter of at least 50 mm, a dislocation density of less than 100 cm −2  and a radial compositional variation of less than 1%. 
   
   
       2 . The composition of  claim 1 , wherein the composition comprises a semiconductor. 
   
   
       3 . The composition of  claim 1 , wherein the single crystal comprises at least a portion of a III-V ternary semiconductor boule. 
   
   
       4 . The composition of  claim 1 , wherein the single crystal comprises a semiconductor wafer. 
   
   
       5 . The composition of  claim 4 , wherein the wafer comprises a ternary III-V semiconductor wafer. 
   
   
       6 . The composition of  claim 4 , further comprising a semiconductor device formed on the semiconductor wafer. 
   
   
       7 . The composition of  claim 1 , wherein the single crystal material comprises a boule comprising at least two regions having different characteristics in an axial direction of the boule, and the regions with different characteristics are of a same or a different type selected from at least one of doping type, doping concentration type, material type and relative element concentration type. 
   
   
       8 . A single crystal growth apparatus, comprising:
 a vessel;   a crystal growth seed mounting area in the vessel;   a crystal growth area in the vessel adjacent to the crystal growth seed mounting area;   a synthesizing melt area in the vessel;   a thermal barrier separating the crystal growth area from the synthesizing melt area, the thermal barrier containing at least one opening connecting the crystal growth area to the synthesizing melt area;   a solute source adapted to provide a solute into the synthesizing melt area;   a heating element adapted to heat vessel to form a growth melt in the crystal growth area and to form a synthesizing melt in the synthesizing melt area.   
   
   
       9 . The apparatus of  claim 8 , wherein the heating element is adapted to maintain a temperature difference between the thermal barrier and a crystal growth surface over the crystal growth seed of 1° C. or less, and a temperature difference between the thermal barrier and a location in the synthesizing melt where the solute is provided of 20° C. or more. 
   
   
       10 . The apparatus of  claim 9 , further comprising:
 a stirrer located in the synthesizing melt area; and   motor adapted to rotate the vessel about its axis.   
   
   
       11 . The apparatus of  claim 8 , wherein:
 the thermal barrier substantially prevents thermal transfer between the synthesizing melt and the growth melt but allows solute transport from the synthesizing melt to the growth melt by solute diffusion through the at least one opening; and   the at least one opening comprises one or more openings located in the thermal barrier, one or more openings located between the thermal barrier and an internal wall of the vessel, or a plurality of openings located in the thermal barrier and between the thermal barrier and an internal wall of the vessel.   
   
   
       12 . The apparatus of  claim 8 , wherein the vessel is oriented vertically, such that the crystal growth seed area is located on a bottom of the vessel, the synthesizing melt area is at a top of the vessel and the crystal growth area is located between the seed and the synthesizing melt area. 
   
   
       13 . The apparatus of  claim 12 , wherein the thermal barrier is located 0.5 cm or less from the upper single crystal surface during the growth of the single crystal, and the at least one opening comprises one or more openings having a width of 2 mm or less. 
   
   
       14 . The apparatus of  claim 8 , wherein the solute source comprises a solid solute feeder vessel having at least one opening which is adapted to be periodically dipped into a melt located in the synthesizing melt area. 
   
   
       15 . The apparatus of  claim 8 , wherein:
 the vessel comprises a vertically oriented crucible; and   the thermal barrier comprises a plate made from a thermally insulating material located in the crucible.   
   
   
       16 . The apparatus of  claim 8 , wherein the solute source comprises a liquid solute feeder vessel adapted to provide a liquid solute into the vessel. 
   
   
       17 . The apparatus of  claim 8 , wherein:
 the vessel comprises a first crucible containing the crystal growth seed area and the growth melt area and a second crucible containing the synthesizing melt area;   the thermal barrier comprises a bottom wall of a second crucible containing the at least one opening; and   the second crucible is located at least partially in the first crucible.   
   
   
       18 . A method of making a semiconductor device, comprising:
 providing a single crystal semiconductor boule comprising at least two semiconductor regions having different characteristics in an axial direction of the boule; and   cutting the boule to form a semiconductor portion of the semiconductor device.   
   
   
       19 . The method of  claim 18 , wherein the regions with different characteristics are of a same or of a different type selected from at least one of doping type, doping concentration type, material type and relative element concentration type. 
   
   
       20 . The method of  claim 18 , wherein:
 the semiconductor device lacks any semiconductor layers which are epitaxially deposited over a substrate; and   the semiconductor regions are not separated from each other by a boundary which is formed by epitaxial semiconductor layer deposition.