Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof

A PVT growth apparatus for PVT growing a SiC single crystal comprising:

• a growth crucible having a side, a top, and a bottom, the top of the growth crucible configured to support a single crystal SiC seed in an interior of the growth crucible, and the bottom of the growth crucible configured to support a SiC source material;
• a growth guide positioned on either side of the single crystal SiC seed and extending from the top of the growth crucible toward the bottom of the growth crucible, terminating above a top level of the SiC source material;
• insulation surrounding an exterior of the growth crucible, said insulation including side, top, and bottom insulation pieces positioned adjacent the respective side, top, and bottom of the growth crucible, the insulation further including an insulation insert positioned in an opening in the top insulation piece, wherein the insulation insert has a thickness less than a thickness of any one of the side, top, and bottom insulation pieces;
• and
• a heater positioned between the bottom of the growth crucible and the bottom insulation piece, wherein a geometry of the insulation insert is tuned to control heat flux in the SiC single crystal that grows on the single crystal SiC seed in use of the PVT growth apparatus, and
• wherein the insulation insert includes a top surface and a bottom surface, and the bottom surface of the insulation insert includes a concave surface portion or a convex surface portion that aids in generating isotherms that have a radial temperature variation in the growth crucible of less than 10° C. between a central axis of the growth crucible and an outside diameter of the single crystal SiC growing on single crystal SiC seed.