Light emitting diode having a barrier layer with a superlattice structure

1. A light emitting diode (LED), comprising non-polar GaN-based semiconductor layers grown on a non-polar substrate,

wherein the non-polar GaN-based semiconductor layers comprise:

a non-polar N-type semiconductor layer;

a non-polar P-type semiconductor layer; and

non-polar active region layers positioned between the non-polar N-type semiconductor layer and the non-polar P-type semiconductor layer,

wherein the non-polar active region layers comprise a well layer and a barrier layer,

wherein the P-type semiconductor layer comprises a P-type clad layer positioned on the active region layers, an undoped layer interposed between the uppermost layer of the non-polar active region layers and the P-type clad layer, a hole injection layer positioned on the P-type clad layer, and a P-type contact layer positioned on the hole injection layer.

2. The LED as claimed in claim 1 , wherein a doping concentration of the hole injection layer is lower than a doping concentration of the P-type clad layer, and a doping concentration of the P-type contact layer is higher than the doping concentration of the P-type clad layer.

3. The LED as claimed in claim 1 , wherein the barrier layer's thicknesses is less than 50 Å.

4. The LED as claimed in claim 3 , wherein the barrier layer comprises a superlattice structure.

5. The LED as claimed in claim 4 , wherein the each layer of superlattice structure have a thickness of 2.5 to 20 Å.

6. The LED as claimed in claim 5 , wherein the superlattice structure has a pair of two layers laminated four to ten times.

7. The LED as claimed in claim 4 , wherein the well layer comprises InGaN, the barrier layer comprises the superlattice structure in which an InGaN layer and an GaN layer are alternately laminated, and InGaN in the well layer comprises a larger amount of In than an amount of InGaN in the barrier layer.

8. The LED as claimed in claim 4 , wherein the well layer comprises In x Ga (1-x) N, and the barrier layer comprises a lower superlattice having In y Ga (1-y) N and GaN alternately laminated, an upper superlattice having In y Ga (1-y) N and GaN alternately laminated, and a middle superlattice interposed between the lower superlattice and the upper superlattice, the middle superlattice having In z Ga (1-z) N and GaN alternately laminated, where 0<x<1, 0<y<0.05, 0<z<0.1 and y<z<x.

9. The LED as claimed in claim 1 , wherein the non-polar active region layers comprise a plurality of well layers and a plurality of barrier layers alternately laminated to form an active region of a multiple quantum well structure.

10. The LED as claimed in claim 1 , wherein the GaN-based semiconductor layers are a-plane GaN-based semiconductor layers grown using an r-plane sapphire substrate or a-GaN substrate as the non-polar substrate.

11. The LED as claimed in claim 7 , wherein the GaN-based semiconductor layers are a-plane GaN-based semiconductor layers grown using an r-plane sapphire substrate or a-GaN substrate as the non-polar substrate.

12. The LED as claimed in claim 8 , wherein the GaN-based semiconductor layers are a-plane GaN-based semiconductor layers grown using an r-plane sapphire substrate or a-GaN substrate as the non-polar substrate.

13. The LED as claimed in claim 9 , wherein the GaN-based semiconductor layers are a-plane GaN-based semiconductor layers grown using an r-plane sapphire substrate or a-GaN substrate as the non-polar substrate.

14. The LED as claimed in claim 1 , wherein the GaN-based semiconductor layers are m-plane GaN-based semiconductor layers grown using an m-plane sapphire substrate or m-GaN substrate as the non-polar substrate.

15. The LED as claimed in claim 7 , wherein the GaN-based semiconductor layers are m-plane GaN-based semiconductor layers grown using an m-plane sapphire substrate or m-GaN substrate as the non-polar substrate.

16. The LED as claimed in claim 8 , wherein the GaN-based semiconductor layers are m-plane GaN-based semiconductor layers grown using an m-plane sapphire substrate or m-GaN substrate as the non-polar substrate.

17. The LED as claimed in claim 9 , wherein the GaN-based semiconductor layers are m-plane GaN-based semiconductor layers grown using an m-plane sapphire substrate or m-GaN substrate as the non-polar substrate.