Light emitting device and method for manufacturing the same
Provided are a light emitting device and a method for manufacturing the same. The light emitting device comprises a first conductive type semiconductor layer, an active layer, a second conductive type semiconductor layer, and a light extraction layer. The active layer is formed on the first conductive type semiconductor layer. The second conductive type semiconductor layer is formed on the active layer. The light extraction layer is formed on the second conductive type semiconductor layer. The light extraction layer has a refractive index smaller than or equal to a refractive index of the second conductive type semiconductor layer.
1. A light emitting device comprising:
a first conductive type semiconductor layer;
an active layer on the first conductive type semiconductor layer;
a second conductive type semiconductor layer on the active layer;
a first electrode layer on the first conductive type semiconductor layer;
a second electrode layer on the second conductive type semiconductor layer; and
a light extraction layer on the second conductive type semiconductor layer, and
wherein the second conductive type semiconductor layer includes a first portion having a center area of the second conductive type semiconductor layer and a second portion having an edge area of the second conductive type semiconductor layer,
wherein the second electrode layer is in contact with a top surface of the first portion of the second conductive type semiconductor layer,
wherein the light extraction layer is disposed on the second portion of the second conductive type semiconductor layer,
wherein the light extraction layer includes a first wall, a second wall and a third wall, and
wherein at least two of the walls have an inner surface inclined at an acute angle wherein the light extraction layer comprises Al x Ga 1-x N (0≦x≦1).
2. The light emitting device according to claim 1 , wherein the light extraction layer having a refractive index smaller than or equal to a refractive index of the second conductive type semiconductor layer.
3. The light emitting device according to claim 1 , wherein the light extraction layer comprises AlGaN.
4. The light emitting device according to claim 1 , wherein the first electrode layer is disposed in an opening that is formed by selectively removing the second conductive type semiconductor layer, the active layer and the first conductive type semiconductor layer.
5. The light emitting device according to claim 1 , wherein the light extraction layer is formed to surround the first electrode layer and the second electrode layer along the peripheral region of the second conductive type semiconductor layer.
6. The light emitting device according to claim 1 , wherein the light extraction layer and the second electrode layer are separated each other on the surface of the second conductive type semiconductor layer.
7. The light emitting device according to claim 1 , wherein each inner surface is inclined at an angle of about 58 degrees to about 63 degrees with respect to the upper surface of the second conductive type semiconductor layer.
8. The light emitting device according to claim 4 , wherein the first electrode layer and the first conductive type semiconductor layer in the opening are upwardly exposed.
9. The light emitting device according to claim 1 , wherein the first conductive type semiconductor layer which the first electrode layer is disposed at is upwardly and laterally exposed.
10. The light emitting device according to claim 1 , comprising an area that is removed from the light extraction layer to a part of the first conductive type semiconductor layer.
11. The light emitting device according to claim 1 , wherein the lateral side surfaces of the light extraction layer, the second conductive type semiconductor layer, the active layer, and the first conductive type semiconductor layer are arranged on the same vertical plane.
12. The light emitting device according to claim 1 , comprising an ohmic contact layer between the second conductive type semiconductor layer and the second electrode layer.
13. The light emitting device according to claim 1 , comprising a third conductive type semiconductor layer on the second conductive type semiconductor layer, the third conductive type semiconductor layer being doped with an n-type impurity.
14. The light emitting device according to claim 1 , wherein an upper surface of the light extraction layer is even.
15. The light emitting device according to claim 1 , wherein a first conductive type semiconductor layer is an N type semiconductor layer and the second conductive type semiconductor layer is a P type semiconductor layer.
16. A light emitting device comprising:
a substrate;
a first conductive type semiconductor layer on the substrate;
an active layer on the first conductive type semiconductor layer;
a second conductive type semiconductor layer on the active layer;
a first electrode layer on the first conductive type semiconductor layer;
a second electrode layer on the second conductive type semiconductor layer; and
a light extraction layer on the second conductive type semiconductor layer,
wherein the second conductive type semiconductor layer includes a first portion having a center area of the second conductive type semiconductor layer and a second portion having an edge area of the second conductive type semiconductor layer,
wherein the second electrode layer is disposed on the first portion of the second conductive type semiconductor layer,
wherein the light extraction layer has a wall disposed on the second portion of the second conductive type semiconductor layer and is not disposed on the first portion of the second conductive type semiconductor layer, and
wherein the wall of the light extraction layer has an inner side surface inclined at an acute angle wherein the light extraction layer comprises Al x Ga 1-x N (0≦x≦1).
17. The light emitting device according to claim 16 , wherein the light extraction layer and the second electrode layer are directly contacted with the second conductive type semiconductor layer.
18. A light emitting device comprising:
a substrate;
a first conductive type semiconductor layer on the substrate;
an active layer on the first conductive type semiconductor layer;
a second conductive type semiconductor layer on the active layer;
a first electrode layer on the first conductive type semiconductor layer;
a second electrode layer on the second conductive type semiconductor layer; and
a light extraction layer on the second conductive type semiconductor layer,
wherein a top surface of the second conductive type semiconductor layer includes a first portion that the light extraction layer is not formed and a second portion,
wherein the light extraction layer has a wall disposed on the second portion of the second conductive type semiconductor layer,
wherein the wall of the light extraction layer includes an inclined side surface, and
wherein the light extraction layer has a central opening and a peripheral opening wherein the light extraction layer comprises Al x Ga 1-x N (0≦x≦1).