Semiconductor light emitting device having an electron barrier layer between a plurality of active layers

1. A semiconductor light emitting device, comprising:

a first conductive type semiconductor layer;

an active layer comprising a first active layer, a second active layer, and an electron barrier layer, the active layer being formed on the first conductive type semiconductor layer,

wherein the first active layer and the second active layer each comprises a quantum well layer and a quantum barrier layer, and

wherein the electron barrier layer is between the first active layer and the second active layer; and

a second conductive type semiconductor layer on the active layer,

wherein the electron barrier layer and at least one of the quantum well layers of the active layer are in contact with each other,

wherein the first and second active layers each comprises a cycle of the quantum well layer and the quantum barrier layer,

wherein the electron barrier layer comprises an AlGaN based semiconductor layer,

wherein an energy band gap of the electron barrier layer is greater than an energy band gap of a quantum barrier layer of the first active layer or an energy band gap of a quantum barrier layer of the second active layer, and

wherein the electron barrier layer is physically contacted with the quantum well layer of the first active layer and the quantum well layer of the second active layer.

2. The semiconductor light emitting device according to claim 1 , wherein the electron barrier layer is in a middle region of the active layer.

3. The semiconductor light emitting device according to claim 1 ,

wherein the electron barrier layer is closer to the first conductive type semiconductor layer than the second conductive type semiconductor layer, and

wherein the first conductive type semiconductor layer is an n-type semiconductor layer.

4. The semiconductor light emitting device according to claim 3 , wherein the cycle of the first active layer is alternatively repeated about four times to about five times, and the cycle of the second active layer is alternatively repeated about five times to about six times.

5. The semiconductor light emitting device according to claim 1 , wherein the electron barrier layer comprises an Al x In y Ga 1-x-y N (0<x≦1, 0≦y<0.5, 0<x+y<1) layer.

6. The semiconductor light emitting device according to claim 1 , wherein the energy band gap of the electron barrier layer is about 1.5 times to about twice greater than the energy band gap of the quantum barrier layer of the first active layer or the energy band gap of the quantum barrier layer of the second active layer.

7. The semiconductor light emitting device according to claim 1 , wherein the electron barrier layer has a thickness thicker than a thickness of the quantum barrier layer of the first active layer or a thickness of the quantum barrier layer of the second active layer.

8. The semiconductor light emitting device according to claim 1 , further comprising:

a first conductive type cladding layer in contact with a lower surface of the active layer; and

a second conductive type cladding layer in contact with an upper surface of the active layer,

wherein the first conductive type cladding layer is an n-type semiconductor layer and the second conductive type cladding layer is a p-type semiconductor layer.

9. The semiconductor light emitting device according to claim 1 , wherein the first conductive type semiconductor layer comprises an n-type semiconductor layer, and the second conductive type semiconductor layer comprises a p-type semiconductor layer.

10. The semiconductor light emitting device according to claim 1 , wherein the quantum well/quantum barrier layers of the first active layer and the second active layer are formed of at least one selected from a group consisting of AlGaN/GaN, InGaN/GaN, and InGaN/InGaN.

11. The semiconductor light emitting device according to claim 1 ,

wherein the electron barrier layer is closer to the first conductive type semiconductor layer than the second conductive type semiconductor layer, and

wherein the first conductive type semiconductor layer is an n-type semiconductor layer.

12. A semiconductor light emitting device comprising:

a first conductive type semiconductor layer;

an active layer on the first conductive type semiconductor layer and comprising a multi-quantum well structure, the active layer comprising an electron barrier layer between a plurality of quantum well layers; and

a second conductive type semiconductor layer on the active layer,

wherein the electron barrier layer is closer to the first conductive type semiconductor layer than the second conductive type semiconductor layer and has a thickness thicker than a thickness of a quantum barrier layer of the active layer,

wherein the electron barrier layer is in physical contact with an upper surface of a first quantum well layer of the plurality of quantum well layers and a lower surface of a second quantum well layer of the plurality of quantum well layers, wherein the first quantum well layer is disposed between the electron barrier layer and the first conductive type semiconductor layer and the second quantum well layer is disposed between the electron barrier layer and the second conductive type semiconductor layer,

wherein the electron barrier layer comprises an AlGaN based semiconductor layer, and

wherein the active layer comprises the multi-quantum well structure with a cycle of the quantum well layer and the quantum barrier layer.

13. The semiconductor light emitting device according to claim 12 , wherein the active layer comprises a cycle of quantum well and quantum barrier layers, the cycle being alternatively repeated about two times to about twenty times.

14. The semiconductor light emitting device according to claim 12 ,

wherein the active layer comprises a first active layer under the electron barrier layer and a second active layer on the electron barrier layer, and a cycle of quantum well and quantum barrier layers of the first active layer is shorter than a cycle of quantum well and quantum barrier layers of the second active layer, and

wherein the electron barrier layer includes an AlGaN based semiconductor layer.

15. The semiconductor light emitting device according to claim 12 , wherein the electron barrier layer comprises a thickness ranging from about 150 Å to about 300 Å.

16. The semiconductor light emitting device according to claim 12 , wherein the electron barrier layer has an energy band gap higher than that of the quantum barrier layer of the active layer.

17. A semiconductor light emitting device, comprising:

a first conductive type semiconductor layer;

an active layer comprising a first active layer, a second active layer, and an electron barrier layer, the active layer being formed on the first conductive type semiconductor layer, wherein the first active layer and the second active layer each comprises a quantum well layer and a quantum barrier layer, and an energy band gap of the electron barrier layer is greater than an energy band gap of the quantum barrier layer of the first active layer and is greater than an energy band gap of the quantum barrier layer of the second active layer; and

a second conductive type semiconductor layer on the active layer,

wherein the active layer comprises a multi-quantum well structure with a cycle of the quantum well layer and the quantum barrier layer,

wherein the electron barrier layer is in physical contact with at least one of the quantum well layers of the active layer, and

wherein the electron barrier layer comprises a laminated structure of an Al x In y Ga 1-x-y N/Al x Ga 1-x N (0<x≦1, 0≦y<0.5, 0<x+y<1) layers.

18. The semiconductor light emitting device according to claim 17 , wherein an upper surface of the electron barrier layer is physically contacted with an upper surface of a quantum well layer of the first active layer and a lower surface of the electron barrier layer is physically contacted with a lower surface of a quantum well layer of the second active layer.

19. The semiconductor light emitting device according to claim 17 , wherein the electron barrier layer comprises a thickness ranging from about 150 Å to about 300 Å.