Apparatus for growth of single crystals including a solute feeder

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 growth melt;
• a synthesizing melt;
• a solute source, wherein the solute source has a chemical composition substantially different than the synthesizing melt;
• a solute feeder adapted to provide a solute into the synthesizing melt area during crystal growth;
• a heating element adapted to heat the vessel to form the growth melt in the crystal growth area and to form the synthesizing melt in the synthesizing melt area,
• 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, and 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.