Light emitting device and lighting system
A light emitting device includes a first electrode layer, a second conductive semiconductor layer on the first electrode layer, an active layer on the second conductive semiconductor layer, and a first conductive semiconductor layer on the active layer. An Al y Ga 1-y N layer (where, 0 y≦1) is provided over the first conductive semiconductor layer, and an In x Ga 1-x N pattern (where, 0 x≦1) is provided over the Al y Ga 1-y N layer. A gallium nitride semiconductor layer is provided over the In x Ga 1-x N pattern; and a pad electrode is provided on the gallium nitride semiconductor layer.
1. A light emitting device comprising:
a first electrode layer;
a second conductive semiconductor layer on the first electrode layer;
an active layer on the second conductive semiconductor layer;
a first conductive semiconductor layer on the active layer;
an Al y Ga 1-y N layer (where, 0 y≦1) on the first conductive semiconductor layer;
an In x Ga 1-x N pattern (where, 0 x≦1) on the Al y Ga 1-y N layer;
a gallium nitride semiconductor layer on the In x Ga 1-x N pattern; and
a pad electrode on the gallium nitride semiconductor layer.
2. The light emitting device of claim 1 , wherein the Al y Ga 1-y N layer comprises a super lattice structure of AlN layer/GaN layer.
3. The light emitting device of claim 1 , wherein the Al y Ga 1-y N layer comprises a super lattice structure of AlGaN layer/GaN layer.
4. The light emitting device of claim 1 , wherein the In x Ga 1-x N pattern is spirally grown.
5. The light emitting device of claim 1 , wherein the In x Ga 1-x N pattern comprises a convex section.
6. The light emitting device of claim 1 , wherein the Al y Ga 1-y N layer comprises a convex section.
7. The light emitting device of claim 6 , wherein the Al y Ga 1-y N layer comprises a section that is convex down along a surface of the In x Ga 1-x N pattern.
8. The light emitting device of claim 1 , wherein the In x Ga 1-x N pattern is formed by a plurality of layers having graded refractive indexes.
9. The light emitting device of claim 1 , wherein the In x Ga 1-x N pattern has a separated island shape.
10. The light emitting device of claim 1 , wherein the first electrode layer comprises an ohmic contact pattern and a reflective layer.
11. The light emitting device of claim 10 , wherein the ohmic contact pattern is interposed between the reflective layer and the second conductive semiconductor layer.
12. The light emitting device of claim 10 , wherein the ohmic contact pattern makes contact with the second conductive semiconductor layer.
13. The light emitting device of claim 10 , wherein the reflective layer vertically overlaps with the Al y Ga 1-y N layer.
14. The light emitting device of claim 10 , wherein the reflective layer vertically overlaps with the In x Ga 1-x N pattern.
15. The light emitting device of claim 1 , further comprising a light transitive channel layer on a bottom portion of the first conductive semiconductor layer.
16. The light emitting device of claim 15 , wherein the light transitive channel layer is vertically overlapped with the In x Ga 1-x N pattern (where, 0 x≦1).
17. The light emitting device of claim 15 , further comprising a support member under the first conductive semiconductor layer, and
a reflective part disposed at a lateral side of the light transitive channel layer and a lateral side of the support member.
18. The light emitting device of claim 17 , wherein a top surface of the reflective part is disposed between In x Ga 1-x N pattern (where, 0 x≦1) and the light transitive channel layer.
19. The light emitting device of claim 1 , wherein a lateral width of the In x Ga 1-x N pattern (where, 0 x≦1) is greater than a lateral width of the active layer.