Group III nitride semiconductor crystal substrate and semiconductor device
A group III nitride semiconductor crystal substrate has a diameter of at least 25 mm and not more than 160 mm. The resistivity of the group III nitride semiconductor crystal substrate is at least 1×10 −4 Ω·cm and not more than 0.1 Ω·cm. The resistivity distribution in the diameter direction of the group III nitride semiconductor crystal is at least −30% and not more than 30%. The resistivity distribution in the thickness direction of the group III nitride semiconductor crystal is at least −16% and not more than 16%.
1. A group III nitride semiconductor crystal substrate having a diameter of at least 25 mm and not more than 160 mm, wherein
a resistivity is at least 1×10 −4 Ω·cm and not more than 0.1 Ω·cm, and
a resistivity distribution in a thickness direction is smaller than a resistivity distribution in a diameter direction,
wherein an upper limit of the resistivity distribution in the diameter direction is obtained by (largest value−average value)/average value, and a lower limit of the resistivity distribution in the diameter direction is obtained by (smallest value−average value)/average value, and wherein an upper limit of the resistivity distribution in the thickness direction is obtained by (largest value−average value)/average value, and a lower limit of the resistivity distribution in the thickness direction is obtained by (smallest value−average value)/average value.
2. The group III nitride semiconductor crystal substrate according to claim 1 , having a thickness of at least 2 mm and not more than 160 mm.
3. The group III nitride semiconductor crystal substrate according to claim 1 , having a thickness of at least 100 μm and not more than 1000 μm.
4. The group III nitride semiconductor crystal substrate according to claim 1 , wherein said resistivity is at least 1×10 −3 Ω·cm and not more than 8×10 −3 Ω·cm.
5. The group III nitride semiconductor crystal substrate according to claim 1 , further comprising a silicon wherein a concentration of said silicon is at least 5×10 16 cm −3 and not more than 5×10 20 cm −3 .
6. The group III nitride semiconductor crystal substrate according to claim 1 , further comprising a silicon wherein a concentration of said silicon is at least 3×10 18 cm −3 and not more than 5×10 19 cm −3 .
7. The group III nitride semiconductor crystal substrate according to claim 1 , wherein a dislocation density is not more than 1×10 7 cm −2 .
8. The group III nitride semiconductor crystal substrate according to claim 1 , wherein a main face has an angle of at least −5 degrees and not more than 5 degrees relative to any one of a (0001) plane, (1-100) plane, (11-20) plane and (11-22) plane.
9. The group III nitride semiconductor crystal substrate according to claim 1 , wherein a full width at half maximum of a rocking curve in X-ray diffraction is at least 10 arcsec and not more than 500 arcsec.
10. The group III nitride semiconductor crystal substrate according to claim 1 , formed of an Al x In y Ga (1-x-y) N (0≦x≦1, 0≦y≦1, x+y≦1) crystal.
11. The group III nitride semiconductor crystal substrate according to claim 1 , formed of a gallium nitride crystal.
12. A semiconductor device comprising:
a group III nitride semiconductor crystal substrate defined in claim 1 , and an epitaxial layer formed on said group III nitride semiconductor crystal substrate.