Nitride semiconductor LED and fabrication method thereof

1. A nitride semiconductor light emitting diode, comprising:

a first conductive semiconductor layer;

an active layer on the first conductive semiconductor layer;

a second conductive semiconductor layer on the active layer;

a fourth semiconductor layer partially protruded on the second conductive semiconductor layer; and

a third conductive semiconductor layer between the fourth semiconductor layer and the second conductive semiconductor layer,

wherein the third conductive semiconductor layer is a super grading In x Ga 1-x N layer whose indium content is sequentially fluctuated.

2. The nitride semiconductor light emitting diode according to claim 1 , wherein the second conductive semiconductor layer and the fourth semiconductor layer are a p-type semiconductor layers.

3. The nitride semiconductor light emitting diode according to claim 1 , wherein the super grading In x Ga 1-x N layer has a range of 0<x<0.2.

4. The nitride semiconductor light emitting diode according to claim 1 , further comprising a fifth semiconductor layer on the fourth semiconductor layer,

wherein the fourth semiconductor layer is formed as fourth semiconductor layer structures that are spaced apart from each other on the third conductive semiconductor layer.

5. The nitride semiconductor light emitting diode according to claim 4 , wherein the fifth semiconductor layer has an InGaN/InGaN or InGaN/AlInGaN super lattice structure.

6. The nitride semiconductor light emitting diode according to claim 4 , wherein a portion of the fifth semiconductor layer is directly formed on the third conductive semiconductor layer and comprises an n-type dopant doped therein.

7. The nitride semiconductor light emitting diode according to claim 1 , wherein the first conductive semiconductor layer is a silicon and indium co-doped GaN layer.

8. The nitride semiconductor light emitting diode according to claim 1 , further comprising an In x Ga 1-x N layer between the first conductive semiconductor and the active layer.

9. The nitride semiconductor light emitting diode according to claim 8 , wherein the In x Ga 1-x N layer is a low-mole In x Ga 1-x N layer having a low indium content.

10. The nitride semiconductor light emitting diode according to claim 8 , further comprising a first SiN x cluster layer and a second SiN x cluster layer formed below and on the In x Ga 1-x N layer, respectively.

11. The nitride semiconductor light emitting diode according to claim 8 , wherein the active layer comprises a pair of an In y Ga 1-y N well layer/In z Ga 1-z N barrier layer, wherein a content of indium doped into the In y Ga 1-y N well layer/In z Ga 1-z N barrier layer and a content of indium doped into the In x Ga 1-x N layer respectively have values of 0<x<0.1, 0<y<0.35, and 0<z<0.1.

12. The nitride semiconductor light emitting diode according to claim 1 , further comprising an In-doped semiconductor layer under the first conductive semiconductor layer.

13. The nitride semiconductor light emitting diode according to claim 1 , further comprising at least one of a substrate and a buffer layer under the first conductive semiconductor layer.

14. The nitride semiconductor light emitting diode according to claim 13 , wherein the buffer layer is formed using a selected one of an AlInN/GaN layered structure, an InGaN/GaN super lattice structure, an In x Ga 1-x N/GaN layered structure, and an Al x In y Ga 1-(x+y) N/In x Ga 1-x N/GaN layered structure.

15. The nitride semiconductor light emitting diode according to claim 1 , wherein the active layer comprises a well layer, a barrier layer on the well layer, and a third SiN x cluster layer formed between the well layer and the barrier layer,

wherein the well layer and the barrier layer have a single quantum well structure or a multi quantum well structure comprising an In y Ga 1-y N well layer/In z Ga 1-z N barrier layer.

16. The nitride semiconductor light emitting diode according to claim 15 , further comprising a GaN cap layer formed between the In y Ga 1-y N well layer and the In z Ga 1-z N barrier layer, where 0<y<0.35 and 0<z<0.1.

17. The nitride semiconductor light emitting diode according to claim 1 , further comprising a SiN x cluster layer formed between the active layer and the second conductive semiconductor layer.

18. The nitride semiconductor light emitting diode according to claim 1 , further comprising an electrode on the fourth semiconductor layer.

19. The nitride semiconductor light emitting diode according to claim 18 , wherein the electrode is formed of transmission metal oxide or transmission resistant metal.

20. The nitride semiconductor light emitting diode according to claim 19 , wherein the transmission metal oxide is a selected one of Indium-Tin-Oxide (ITO), Zinc Oxide (ZnO), iridium oxide (IrOx), ruthenium oxide (RuOx), and nickel oxide (NiO).

21. The nitride semiconductor light emitting diode according to claim 19 , wherein the transmission resistant metal is aurum (Au) alloy containing nickel (Ni).

22. A nitride semiconductor light emitting diode, comprising:

a first conductive semiconductor layer;

an active layer on the first conductive semiconductor layer;

a second conductive semiconductor layer on the active layer; and

a fourth semiconductor layer partially protruded on the second conductive semiconductor layer,

wherein the active layer includes a In y Ga 1-y N well layer, a GaN cap layer and a In z Ga 1-z N barrier layer and has a single quantum well structure or a multi quantum well structure, and wherein the GaN cap layer is formed between the well layer and the barrier layer.

23. The nitride semiconductor light emitting diode according to claim 22 , wherein the In y Ga 1-y N well layer and the In z Ga 1-z N barrier layer have values of 0<y<0.35 and 0<z<0.1.

24. The nitride semiconductor light emitting diode according to claim 22 , further comprising a third conductive semiconductor layer between the fourth semiconductor layer and the second conductive semiconductor layer,

wherein the third conductive semiconductor layer is a In x Ga 1-x N layer, in which an indium content of the In x Ga 1-x N layer is sequentially fluctuated.

25. The nitride semiconductor light emitting diode according to claim 22 , wherein the fourth semiconductor layer is formed as fourth semiconductor layer structures that are spaced apart from each other on the second conductive semiconductor layer.

26. The nitride semiconductor light emitting diode according to claim 25 , further comprising an electrode on the fourth semiconductor layer and the second conductive semiconductor layer.

27. The nitride semiconductor light emitting diode according to claim 25 , further comprising a fifth semiconductor layer formed on the fourth semiconductor layer.

28. The nitride semiconductor light emitting diode according to claim 27 , further comprising a third conductive semiconductor layer between the fourth semiconductor layer and the second conductive semiconductor layer, wherein the third conductive semiconductor layer and/or the fifth semiconductor layer has an InGaN/InGaN or InGaN/AlInGaN super lattice structure.

29. The nitride semiconductor light emitting diode according to claim 22 , wherein the first conductive semiconductor layer comprises a silicon and indium co-doped GaN layer which is an n-type semiconductor layer.

30. The nitride semiconductor light emitting diode according to claim 22 , further comprising an In x Ga 1-x N layer between the first conductive semiconductor layer and the active layer.

31. The nitride semiconductor light emitting diode according to claim 22 , further comprising a first SiN x cluster layer and a second SiN x cluster layer formed below and on the In x Ga 1-x N layer, respectively.

32. The nitride semiconductor light emitting diode according to claim 22 , further comprising a SiN x cluster layer formed between the active layer and the second conductive semiconductor layer.