Gallium nitride substrate and manufacturing method of nitride semiconductor crystal
A gallium nitride substrate comprising a first main surface and a second main surface opposite thereto, wherein the first main surface is a non-polar or semi-polar plane, a dislocation density measured by a room-temperature cathode luminescence method in the first main surface is 1×10 4 cm −2 or less, and an averaged dislocation density measured by a room-temperature cathode luminescence method in an optional square region sizing 250 μm×250 μm in the first main plan is 1×10 6 cm −2 or less.
1. A gallium nitride substrate comprising a first main surface and a second main surface opposite thereto,
wherein the first main surface is a non-polar or semi-polar plane,
a dislocation density measured by a room-temperature cathode luminescence method averaged over a whole of the first main surface is 1×10 4 cm −2 or less, and
an averaged dislocation density measured by a room-temperature cathode luminescence method in an arbitrary selected square region sizing 250 μm×250 μm in the first main surface is 1×10 6 cm −2 or less.
2. A gallium nitride substrate according to claim 1 , wherein the dislocation density is 10 cm −2 or less.
3. A gallium nitride substrate according to claim 1 , wherein the averaged dislocation density is 1×10 4 cm −2 or less.
4. A gallium nitride substrate according to claim 1 , wherein an area of the first main surface is 1.0 cm 2 or more.
5. A gallium nitride substrate according to claim 1 , wherein a stacking fault density in the first main surface is 10 cm −1 or less.
6. A gallium nitride substrate according to claim 1 , wherein the first main surface is an M-plane.
7. A gallium nitride substrate according to claim 1 ,
wherein the first main surface has a normal vector of which is tilted from <10-10> direction to c-axis direction, and
the normal vector is between <10-11> direction and <10-1-1> direction.
8. A gallium nitride substrate according to claim 7 , wherein the normal vector is a direction selected from the group consisting of a <30-31> direction, a <30-3-1> direction, a <20-21> direction, a <20-1-1> direction, a <10-11> direction, a <10-1-1> direction, a <10-12> direction, a <10-1-2> direction, a <10-13> direction, a <10-1-3> direction, a <11-21> direction, a <11-2-1> direction, a <11-22> direction, a <11-2-2> direction, a <11-23> direction and a <11-2-3> direction.
9. A method for manufacturing a nitride semiconductor crystal, comprising:
growing a nitride semiconductor crystal on the first main surface of the gallium nitride substrate according to claim 1 .
10. The method according to claim 9 , wherein in the growing of the nitride semiconductor crystal, the nitride semiconductor crystal is grown by a vapor phase growth method.
11. The method according to claim 10 , wherein the vapor phase growth method is HVPE method.
12. The method according to claim 11 , wherein in the growing of the nitride semiconductor crystal, a bulk nitride semiconductor crystal is grown.
13. The method according to claim 10 , wherein the vapor phase growth method is MOCVD method.
14. The method according to claim 13 , wherein in the growing of the nitride semiconductor crystal, a thin film of the nitride semiconductor crystal is grown.
15. The method according to claim 9 , wherein in the growing of the nitride semiconductor crystal, the nitride semiconductor crystal grown directly on the first main surface is a GaN crystal.