Group III-V nitride series semiconductor substrate and assessment method therefor
View Patent ↗The group III-V nitride series semiconductor substrate has good-product yield when the band-edge peak light-emission intensity ratio α=N 1 /N 2 is α<1, where N 1 is a band-edge peak light-emission intensity at an arbitrary photoluminescence measurement position on the front side of the substrate, and N 2 is a band-edge peak light-emission intensity on the back side of the substrate corresponding to the photoluminescence measurement position.
1. A group III-V nitride series semiconductor substrate, comprising:
a self-standing group III-V nitride series semiconductor crystal with both its front and back sides being ground to a mirror finish, and with the band-edge peak light-emission intensity ratio α=N 1 /N 2 being a α<1, where N 1 is a band-edge peak light-emission intensity at an arbitrary photoluminescence measurement position on the front side, and N 2 is a band-edge peak light-emission intensity on the back side corresponding to said photoluminescence measurement position,
wherein said semiconductor crystal comprises a hexagonal gallium nitride monocrystalline crystal, the front side of which comprises a C-face gallium surface.
2. The group III-V nitride series semiconductor substrate according to claim 1 , wherein said intensity ratio α is 0.1≦α≦0.5.
3. The group III-V nitride series semiconductor substrate according to claim 1 , wherein said semiconductor crystal comprises an n-type impurity-doped conductive crystal.
4. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the band-edge peak light-emission intensity comprises a photoluminescence peak intensity corresponding to bandgap energy of the self-standing group III-V nitride series semiconductor crystal.
5. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the band-edge peak light-emission includes a peak at about 365 nm.
6. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the band-edge peak light-emission intensity is dependent on a machined damaged layer of a substrate surface.
7. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the band-edge peak light-emission intensity is dependent on a carrier concentration of a substrate.
8. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the band-edge peak light-emission intensity is dependent on defects on the self-standing group III-V nitride series semiconductor crystal.
9. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the band-edge peak light-emission intensity decreases on the back-side.
10. The group III-V nitride series semiconductor substrate according to claim 1 , wherein a number of impurity atoms is greater on the back side than the front side.
11. The group III-V nitride series semiconductor substrate according to claim 1 , further comprising an electrode disposed on the self-standing group III-V nitride series semiconductor crystal.
12. The group III-V nitride series semiconductor substrate according to claim 1 , wherein the back side comprises a surface roughness of about 1 μm or larger.
13. The group III-V nitride series semiconductor substrate according to claim 5 , wherein the band-edge peak light-emission intensity of the back side is about 1.4×10 6 .
14. The group III-V nitride series semiconductor substrate according to claim 13 , wherein the band-edge peak light-emission intensity of the front side is about 0.18×10 6 .
15. The group III-V nitride series semiconductor substrate according to claim 1 , wherein α is about 0.13-0.39.
16. The group III-V nitride series semiconductor substrate according to claim 1 , wherein α is about 0.49.
17. The group III-V nitride series semiconductor substrate according to claim 1 , wherein α is about 0.77-0.98.