Nitride semiconductor light emitting device

1. A nitride semiconductor light emitting device comprising:

an n-type semiconductor region;

an active layer formed on the n-type semiconductor region;

a p-type semiconductor region formed on the active layer;

an n-electrode disposed in contact with the n-type semiconductor region;

a p-electrode formed on the p-type semiconductor region; and

at least one intermediate layer formed in at least one of the n-type semiconductor region and the p-type semiconductor region, the intermediate layer disposed above the n-electrode,

wherein the intermediate layer is formed of a multi-layer structure where at least three layers with different band gaps from one another are deposited,

the multi-layer structure comprises one of an AlGaN layer/GaN layer/InGaN layer stack and an InGaN layer/GaN layer/AlGaN layer stack, and

at least two of the AlGaN layer, the GaN layer and InGaN layer have a different concentration of dopant or a different doping type from one another.

2. The nitride semiconductor light emitting device of claim 1 , wherein the intermediate layer is formed of a multi-layer structure where one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack is deposited repeatedly.

3. The nitride semiconductor light emitting device of claim 1 , wherein the intermediate layer is formed of a superlattice structure where one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack is deposited repeatedly.

4. The nitride semiconductor light emitting device of claim 1 , wherein each of the layers of the intermediate layer has a thickness of 10 to 300 Å.

5. The nitride semiconductor light emitting device of claim 1 , wherein the intermediate layer is formed of a multi-layer structure where an AlGaN layer/GaN layer/InGaN layer/GaN layer stack comprises one period and is deposited repeatedly.

6. The nitride semiconductor light emitting device of claim 1 , wherein the intermediate layer is formed of a multi-layer structure modulation-doped for mobility modulation.

7. The nitride semiconductor light emitting device of claim 1 , wherein in one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack, the AlGaN layer, the GaN layer, and InGaN layer are doped to a different concentration or with a different doping type from one another.

8. The nitride semiconductor light emitting device of claim 7 , wherein in the one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack, the AlGaN layer is doped with a first conductivity, the GaN layer is undoped and the InGaN layer is doped with a second conductivity.

9. The nitride semiconductor light emitting device of claim 7 , wherein in the one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack, the AlGaN layer is one of p-doped and undoped, the GaN layer is n-doped and the InGaN layer is undoped.

10. The nitride semiconductor light emitting device of claim 1 , wherein in the one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack, the inside of at least one of the AlGaN layer, GaN layer and InGaN layer is modulation-doped.

11. The nitride semiconductor light emitting device of claim 10 , wherein in the one of the AlGaN layer/GaN layer/InGaN layer stack and the InGaN layer/GaN layer/AlGaN layer stack, at least one of the AlGaN layer, GaN layer and InGaN layer is formed of a modulation-doped structure having one of a p-type layer/n-type layer/p-type layer stack and an n-type layer/p-type layer/n-type layer stack.

12. The nitride semiconductor light emitting device of claim 1 , wherein the intermediate layer is at least partially In-doped.

13. The nitride semiconductor light emitting device of claim 1 , wherein the nitride semiconductor light emitting device comprises a light emitting diode where the n-electrode and the p-electrode are positioned on the same side of the light emitting diode.

14. The nitride semiconductor light emitting device of claim 13 , further comprising a substrate disposed below the n-type semiconductor region.

15. The nitride semiconductor light emitting device of claim 1 , wherein the nitride semiconductor light emitting device comprises a light emitting diode where the n-electrode is formed on an opposing side of the p-electrode.

16. The nitride semiconductor light emitting device of claim 15 , further comprising a conductive substrate, wherein the n-type semiconductor region is interposed between the active layer and the conductive substrate.

17. The nitride semiconductor light emitting device of claim 15 , further comprising a conductive substrate wherein the p-type semiconductor region is interposed between the active layer and the conductive substrate.

18. The nitride semiconductor light emitting device of claim 14 , wherein the substrate has a top surface defining a crystal plane for non-polar GaN layer growth.

19. The nitride semiconductor light emitting device of claim 16 , wherein the conductive substrate has a top surface defining a crystal plane for non-polar GaN layer growth.

20. The nitride semiconductor light emitting device of claim 17 , wherein the conductive substrate has a top surface defining a crystal plane for non-polar GaN layer growth.

21. The nitride semiconductor light emitting device of claim 14 , wherein the substrate comprises one of a-plane sapphire, r-plane sapphire, m-plane sapphire, SiC, LiAlO 2 , ZnO and m-plane GaN.

22. The nitride semiconductor light emitting device of claim 16 , wherein the conductive substrate comprises one of SiC, ZnO and m-plane GaN.

23. The nitride semiconductor light emitting device of claim 17 , wherein the conductive substrate comprises one of SiC, ZnO and m-plane GaN.