Light-emitting element

1. A light-emitting element comprising:

a first semiconductor stack having a first conductivity type;

an active layer formed on the first semiconductor stack;

a second semiconductor stack having a second conductivity type formed on the active layer; and

a first current-spreading layer having the first conductivity type interposed in the second semiconductor stack; wherein the second semiconductor stack comprises an electron-blocking layer formed between the active layer and the first current-spreading layer.

2. The light-emitting element according to claim 1 , wherein the first semiconductor stack, the active layer and the second semiconductor stack comprise nitride based semiconductor, and the first conductivity type comprises n-type, and the second conductivity type comprises p type.

3. The light-emitting element according to claim 2 , wherein the first conductivity type of the first current-spreading layer comprises intentionally doped n-type or un-intentionally doped n-type.

4. The light-emitting element according to claim 2 , wherein the first current-spreading layer comprises an n-type GaN layer and/or the first current-spreading layer comprises a higher resistance for holes than the second semiconductor stack.

5. The light-emitting element according to claim 2 , further comprising a second current-spreading layer, being undoped or un-intentionally doped and adjacent to the first current-spreading layer, and interposed in the second semiconductor stack.

6. The light-emitting element according to claim 5 , wherein the second current-spreading layer comprises GaN or AlGaN.

7. The light-emitting element according to claim 5 , wherein the second current-spreading layer comprises a thickness between 15 Å and 40 Å.

8. The light-emitting element according to claim 5 , wherein the second current-spreading layer is closer to the active layer than the first current-spreading layer.

9. The light-emitting element according to claim 5 , wherein the second current-spreading layer has an Al composition between 10% and 20%.

10. The light-emitting element according to claim 1 , wherein the first current-spreading layer comprises a thickness between 50 Å and 100 Å.

11. The light-emitting element according to claim 1 , wherein the second semiconductor stack comprises an upper side and a bottom side closer to the active layer than the upper side, and the first current-spreading layer is closer to the bottom side than the upper side.

12. A light-emitting element comprising:

a semiconductor light-emitting stack;

a p-type semiconductor stack formed in the semiconductor light-emitting stack; and

a first current-spreading layer comprising an undoped layer interposed in the p-type semiconductor stack; wherein the undoped layer comprises an un-intentionally doped layer.

13. The light-emitting element according to claim 12 , wherein the semiconductor light-emitting stack comprises an n-type semiconductor stack, an active layer formed on the n-type semiconductor stack and the p-type semiconductor stack formed on the active layer.

14. The light-emitting element according to claim 12 , wherein the first current-spreading layer comprises GaN or AlxGa1-xN, and x is between 0.1 and 0.2 and/or the first current-spreading layer comprises a thickness between 15 Å and 40 Å or between 50 Å and 100 Å.

15. The light-emitting element according to claim 13 , wherein the p-type semiconductor stack comprises an electron-blocking layer formed between the active layer and the first current-spreading layer.

16. The light-emitting element according to claim 15 , wherein the electron-blocking layer comprises AlGaN and the first current-spreading layer comprises AlGaN, and an Al composition of the electron-blocking layer is higher than that of the first current-spreading layer.

17. The light-emitting element according to claim 13 , further comprising a second current-spreading layer, being undoped or un-intentionally doped and adjacent to the first current-spreading layer, and interposed in the p-type semiconductor stack.

18. The light-emitting element according to claim 17 , wherein the second current-spreading layer comprises GaN or AlGaN.

19. The light-emitting element according to claim 17 , wherein the second current-spreading layer is closer to the active layer than the first current-spreading layer.

20. The light-emitting element according to claim 13 , wherein the p-type semiconductor stack comprises an upper side and a bottom side closer to the active layer than the upper side, and the first current-spreading layer is closer to the bottom side than the upper side.