Silicon carbide substrate and method of growing SiC single crystal boules
The present invention relates to a silicon carbide (SiC) substrate with improved mechanical and electrical characteristics. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. The silicon carbide substrate comprises an inner region ( 102 ) which constitutes at least 30% of a total surface area of said substrate ( 100 ), a ring shaped peripheral region ( 104 ) radially surrounding the inner region ( 102 ), wherein a mean concentration of a dopant in the inner region ( 102 ) differs by at maximum 5·10 18 cm −3 , preferably 1·10 18 cm −3 , from the mean concentration of this dopant in the peripheral region ( 104 ).
1. Bulk silicon carbide substrate, comprising:
a doped inner region which forms 45%±15% of a total surface area of said substrate; and
a ring shaped peripheral region doped with a concentration of a dopant different from a concentration of the dopant in the inner region and radially surrounding the inner region,
wherein a mean concentration of the dopant in the inner region differs by no more than 1·10 18 cm −3 from a mean concentration of this dopant in the peripheral region, and wherein a maximum deviation of mean absorption coefficients of the inner region and the peripheral region is less than 5 cm −1 .
2. Bulk silicon carbide substrate according to claim 1 , wherein said dopant comprises nitrogen.
3. Bulk silicon carbide substrate according to claim 1 , wherein the substrate has a polytype selected from a group comprising 4H, 6H, 15R, and 3C.
4. Bulk silicon carbide substrate according to claim 1 , wherein the substrate has a thickness of less than 1000 μm and/or wherein the substrate has a diameter of at least 100 mm.
5. Bulk silicon carbide substrate according to claim 1 , wherein the substrate has an electrical resistivity in a range from 12 mΩ cm to 26 mΩ cm, and/or an etch pit density of less than 50000 cm −2 .