Nitride semiconductor light emitting device
The present invention relates to a nitride semiconductor light emitting device including: a first nitride semiconductor layer having a super lattice structure of AlGaN/n-GaN or AlGaN/GaN/n-GaN; an active layer formed on the first nitride semiconductor layer to emit light; a second nitride semiconductor layer formed on the active layer; and a third nitride semiconductor layer formed on the second nitride semiconductor layer. According to the present invention, the crystallinity of the active layer is enhanced, and optical power and reliability are also enhanced.
1. A nitride semiconductor light emitting device comprising:
a first nitride semiconductor layer having a super lattice structure of AlGaN/n-GaN or AlGaN/GaN/n-GaN;
an active layer formed above the first nitride semiconductor layer to emit light;
a second nitride semiconductor layer formed above the active layer; and
a third nitride semiconductor layer formed above the second nitride semiconductor layer,
wherein the active layer is formed in a single quantum well layer or a multi quantum well layer comprising a well layer and a barrier layer, and a SiNx cluster layer formed between the well layer and the barrier layer.
2. The nitride semiconductor light emitting device according to claim 1 , wherein the first nitride semiconductor layer is a first electrode contact layer and the third nitride semiconductor layer comprises n-InGaN and is provided as a second electrode contact layer to form a junction structure of n-/p-/n-.
3. The nitride semiconductor light emitting device according to claim 1 , further comprising:
a substrate; and
a buffer layer formed above the substrate,
wherein the substrate and the buffer layer are formed below the first nitride semiconductor layer.
4. The nitride semiconductor light emitting device according to claim 3 , further comprising an indium-doped nitride semiconductor layer formed above the buffer layer.
5. The nitride semiconductor light emitting device according to claim 3 , wherein the buffer layer has a structure selected from the group consisting of a stack structure of AlInN/GaN, a super lattice structure of InGaN/GaN, a stack structure of In x Ga 1-x N/GaN, and a stack structure of Al x In y Ga 1-(x+y) N/In x Ga 1-x N/GaN.
6. The nitride semiconductor light emitting device according to claim 3 , wherein the first nitride semiconductor layer has a higher growth temperature than that of the buffer layer.
7. The nitride semiconductor light emitting device according to claim 1 , wherein the first nitride semiconductor layer has an overall thickness range of 1-2 μm.
8. The nitride semiconductor light emitting device according to claim 1 , wherein the AlGaN layer of the first nitride semiconductor layer is an undoped layer and has an Al composition of 5-30%.
9. The nitride semiconductor light emitting device according to claim 1 , wherein the AlGaN layer of the first nitride semiconductor layer is formed in a thickness range of 10-200 Å.
10. The nitride semiconductor light emitting device according to claim 1 , wherein the second nitride semiconductor layer is a p-type nitride semiconductor layer.
11. The nitride semiconductor light emitting device according to claim 1 , wherein the first nitride semiconductor layer has the super lattice structure of AlGaN/GaN/n-GaN and the GaN layer of the first nitride semiconductor layer is an undoped layer and is formed in a thickness range of 10-200 Å.
12. The nitride semiconductor light emitting device according to claim 1 , wherein the n-GaN layer of the first nitride semiconductor layer is doped with silicon, or silicon and indium.
13. The nitride semiconductor light emitting device according to claim 1 , wherein the n-GaN layer of the first nitride semiconductor layer is formed in a thickness range of 200-500 Å.
14. The nitride semiconductor light emitting device according to claim 1 , wherein the n-GaN layer of the first nitride semiconductor layer has a doping concentration range of 1×10 18 /cm 3 -5×10 18 /cm 3 .
15. The nitride semiconductor light emitting device according to claim 1 , further comprising a low mole indium-containing nitride layer formed between the first nitride semiconductor layer and the active layer and having an indium content of 1-5%.
16. The nitride semiconductor light emitting device according to claim 15 , wherein the low mole indium-containing nitride layer has a spiral shape and a thickness range of 100-300 Å.
17. The nitride semiconductor light emitting device according to claim 1 , wherein the third nitride semiconductor layer is formed of an n-InGaN layer with an SG (super grading) structure in which indium content is gradually varied.
18. The nitride semiconductor light emitting device according to claim 1 , further comprising a transparent electrode formed above the third nitride semiconductor layer.
19. The nitride semiconductor light emitting device according to claim 18 , wherein the transparent electrode is formed of one selected from the group consisting of ITO, IZO(In—ZnO), GZO(Ga—ZnO), AZO(Al—ZnO), AGZO(Al—Ga ZnO), IGZO(In—Ga ZnO), IrO x , RuO x , RuO x /ITO, Ni/IrO x /Au, and Ni/IrO x /Au/ITO.
20. A method of fabricating a nitride semiconductor light emitting device, the method comprising:
forming a first nitride semiconductor layer serving as a first electrode contact layer in a super lattice structure of AlGaN/n-GaN or AlGaN/GaN/n-GaN;
forming an active layer above the first nitride semiconductor layer; and
forming a second nitride semiconductor layer above the active layer,
wherein forming the active layer comprises forming a single quantum well layer or a multi quantum well layer comprising a well layer and a barrier laver, and forming a SiNx cluster layer between the well layer and the barrier layer.
21. The method according to claim 20 , further comprising forming a third nitride semiconductor layer above the second nitride semiconductor layer, wherein the third nitride semiconductor layer is a second electrode contact layer.
22. The method according to claim 21 , wherein the third nitride semiconductor layer is formed of an n-InGaN layer with an SG (super grading) structure in which indium content is gradually varied.
23. The method according to claim 20 , wherein the first nitride semiconductor layer has an overall thickness range of 1-2 μm.
24. The method according to claim 20 , wherein the AlGaN layer of the first nitride semiconductor layer is an undoped layer and is formed in a thickness range of 10-200 Åwith an Al composition of 5-30%.
25. The method according to claim 20 , wherein the first nitride semiconductor layer has the super lattice structure of AlGaN/GaN/n-GaN and the GaN layer of the first nitride semiconductor layer is an undoped layer and is formed in a thickness range of 10-200 Å.
26. The method according to claim 20 wherein the n-GaN layer of the first nitride semiconductor layer has a doping concentration range of 1×10 18 /cm 3 -5×10 18 /cm 3 .