Lightly doped silicon carbide wafer and use thereof in high power devices
View Patent ↗A uniform silicon carbide single crystal with either an n-type or a p-type conductivity. The crystal has a net carrier concentration less than 10 15 cm −3 and a carrier lifetime of at least 50 ns at room temperature.
1. A uniform silicon carbide single crystal with either an n-type or a p-type conductivity, wherein the crystal has a net carrier concentration less than 10 15 cm −3 and a carrier lifetime of at least 50 ns at room temperature, wherein the single crystal is a wafer.
2. The silicon carbide crystal according to claim 1 , wherein dopants conferring said n-type or p-type conductivity to the crystal are either shallow donors, comprising nitrogen, or shallow acceptors, comprising aluminum.
3. The silicon carbide crystal according to claim 1 , wherein the wafer has been sliced from an originally produced crystal.
4. The silicon carbide crystal according to claim 1 , wherein the wafer is polished.
5. The silicon carbide crystal according to claim 1 , wherein the surface of the wafer is either off-oriented towards a Miller index direction with an off-axis angle less than 1 degree or on-axis, that is parallel to a Miller index plane.
6. The silicon carbide crystal according to claim 1 , wherein the wafers has a thickness that exceeds 100 μm.
7. The silicon carbide crystal according to claim 3 , wherein the originally produced crystal has been grown as a boule.
8. The silicon carbide crystal according to claim 1 , wherein the wafer has a thickness that exceeds 150 μm.
9. The silicon carbide crystal according to claim 1 , wherein the crystal has a boron concentration less than 5×10 14 cm −3 , and a concentration of transition metals impurities less than 5×10 14 cm −3 .
10. The silicon carbide crystal according to claim 1 , wherein the crystal has a boron concentration less than 5×10 15 cm −3 , and a concentration of transition metals impurities less than 10 13 .
11. The silicon carbide crystal according to claim 1 , wherein the crystal after growth has been annealed to above 700° C. for a time sufficient to increase the carrier life time to said at least 50 ns.
12. The silicon carbide crystal according to claim 1 , further comprising:
a semiconductor device built on the wafer.