Group III nitride semiconductor substrate having a sulfide in a surface layer
In a semiconductor device 100 , it is possible to prevent C from piling up at a boundary face between an epitaxial layer 22 and a group III nitride semiconductor substrate 10 by the presence of 30×10 10 pieces/cm 2 to 2000×10 10 pieces/cm 2 of sulfide in terms of S and 2 at % to 20 at % of oxide in terms of O in a surface layer 12 . By thus preventing C from piling up, a high-resistivity layer is prevented from being formed on the boundary face between the epitaxial layer 22 and the group III nitride semiconductor substrate 10 . Accordingly, it is possible to reduce electrical resistance at the boundary face between the epitaxial layer 22 and the group III nitride semiconductor substrate 10 , and improve the crystal quality of the epitaxial layer 22 . Consequently, it is possible to improve the emission intensity and yield of the semiconductor device 100.
1. A group III nitride semiconductor substrate used in a semiconductor device, comprising a surface layer on a surface of the group III nitride semiconductor substrate, wherein
the surface layer contains 30×10 10 pieces/cm 2 to 2000×10 10 pieces/cm 2 of sulfur and 2 atomic percentage to 20 atomic percentage of oxygen.
2. The group III nitride semiconductor substrate according to claim 1 , wherein the surface layer contains 40×10 10 pieces/cm 2 to 1500×10 10 pieces/cm 2 of sulfur.
3. The group III nitride semiconductor substrate according to claim 1 , wherein the surface layer contains 3 atomic percentage to 1.6 atomic percentage of oxygen.
4. The group III nitride semiconductor substrate according to claim 1 , wherein the surface layer contains 120×10 10 pieces/cm 2 to 15000×10 10 pieces/cm 2 of chlorine.
5. The group III nitride semiconductor substrate according to claim 1 , wherein the surface layer contains 100×10 10 pieces/cm 2 to 12000×10 10 pieces/cm 2 of silicon.
6. The group III nitride semiconductor substrate according to claim 1 , wherein a content of carbon compound in the surface layer is 22 atomic percentage or less of carbon.
7. The group III nitride semiconductor substrate according to claim 1 , wherein a content of copper compound in the surface layer is 150×10 10 pieces/cm 2 or lower of copper.
8. The group III nitride semiconductor substrate according to claim 1 , wherein a surface roughness of the surface layer is 5 nm or less on an RMS basis.
9. The group III nitride semiconductor substrate according to claim 1 , wherein a dislocation density of the surface layer is 1×10 6 pieces/cm 2 or lower.
10. The group III nitride semiconductor substrate according to claim 1 , wherein an inclination angle of a normal axis of the surface with respect to a c-axis is 10° to 81°.
11. The group III nitride semiconductor substrate according to claim 1 , wherein a plane orientation of the surface is one of a {20-21} plane, a {10-11} plane, a {20-2-1} plane, a {10-1-1} plane, a {11-22} plane, a {22-43} plane, a {11-21} plane, a {11-2-2} plane, a {22-4-3} plane and a {11-2-1} plane.
12. An epitaxial substrate, comprising the group III nitride semiconductor substrate according to claim 1 and an epitaxial layer formed on the surface layer of the group III nitride semiconductor substrate, wherein the epitaxial layer contains a group III nitride semiconductor.
13. The epitaxial substrate according to claim 12 , wherein
the epitaxial layer comprises an active layer having a quantum well structure, and
the active layer is provided so as to emit light of 430 nm to 550 nm in wavelength.
14. A semiconductor device comprising the epitaxial substrate according to claim 12 .
15. A semiconductor device comprising the epitaxial substrate according to claim 13 .
16. The group III nitride semiconductor substrate according to claim 1 , wherein the surface layer contains 50000×10 10 pieces/cm 2 or more of silicon.