Light emitting device
Provided are a light emitting device, a method of fabricating the light emitting device, a light emitting device package, and a lighting system. The light emitting device comprises a substrate, a first semiconductor layer containing indium (In) over the substrate, and a light emitting structure over the first semiconductor layer. A dislocation mode is disposed on a top surface of the first semiconductor layer.
1. A light emitting device comprising:
a substrate;
a first semiconductor layer containing indium (In) over the substrate;
an undoped semiconductor layer comprising a protrusion portion and a recessed portion over the first semiconductor layer; and
a light emitting structure over the undoped semiconductor layer,
wherein a dislocation mode is disposed on a top surface of the first semiconductor layer,
wherein the recessed portion has a resistance greater than that of the protrusion portion,
wherein the protrusion portion and the recessed portion constitute a wedge-type embayment portion, and
wherein the wedge-type embayment portion comprises a peak having a resistance greater than that of a growth surface of the first semiconductor layer.
2. The light emitting device according to claim 1 , wherein the dislocation mode comprises a plurality of dislocation modes, and the plurality of dislocation modes are uniformly distributed.
3. The light emitting device according to claim 1 , wherein the first semiconductor layer comprises one of an In x GaN 1-x /GaN (0<x≦1) superlattice structure and an InN/GaN superlattice structure.
4. The light emitting device according to claim 1 , further comprising a nitride semiconductor superlattice layer over the undoped semiconductor layer.
5. The light emitting device according to claim 4 , wherein the nitride semiconductor superlattice layer is directly disposed on the undoped semiconductor layer.
6. The light emitting device according to claim 4 , wherein at least one pit is disposed between the protrusion portion and another protrusion portion of the undoped semiconductor layer.
7. The light emitting device according to claim 6 , wherein the nitride semiconductor superlattice layer is disposed on a top surface of the at least one pit.
8. The light emitting device according to claim 1 , wherein the light emitting structure comprises:
a first conductive type semiconductor layer;
an active layer over the first conductive type semiconductor layer; and
a second conductive type semiconductor layer over the active layer.
9. The light emitting device according to claim 8 , further comprising:
a first electrode in a region in which a portion of the first conductive type semiconductor layer is exposed; and
a second electrode over the second conductive type semiconductor layer.
10. The light emitting device according to claim 1 , wherein the first semiconductor layer comprises an In x Ga 1-x (0<x≦1) structure or an In x GaN 1-x /GaN (0<x≦1) superlattice structure.
11. The light emitting device according to claim 10 , wherein a composition ratio (X) of the indium (In) ranges from about 0.02 to about 0.05.
12. A light emitting device comprising:
a substrate;
a first conductive type semiconductor layer over the substrate;
an indium-containing first semiconductor layer over the first conductive type semiconductor layer;
an undoped semiconductor layer comprising a protrusion portion and a recessed portion over the indium-containing first semiconductor layer;
an active layer over the undoped semiconductor layer; and
a second conductive type semiconductor layer over the active layer,
wherein a dislocation mode is disposed on a top surface of the first semiconductor layer,
wherein the recessed portion has a resistance greater than that of the protrusion portion,
wherein the protrusion portion and the recessed portion constitute a wedge-type embayment portion, and
wherein the wedge-type embayment portion comprises a peak having a resistance greater than that of a growth surface of the first semiconductor layer.
13. The light emitting device according to claim 12 , wherein the dislocation mode comprises a plurality of dislocation modes, and the plurality of dislocation modes are uniformly distributed.
14. The light emitting device according to claim 12 , further comprising:
a first electrode in a region in which a portion of the first conductive type semiconductor layer under the first semiconductor layer is exposed; and
a second electrode over the second conductive type semiconductor layer.
15. The light emitting device according to claim 12 , further comprising a nitride semiconductor superlattice layer over the undoped semiconductor layer.
16. The light emitting device according to claim 15 , wherein the nitride semiconductor superlattice layer is directly disposed on the undoped semiconductor layer.
17. The light emitting device according to claim 15 , wherein at least one pit is disposed between the protrusion portion and another protrusion portion of the undoped semiconductor layer.
18. The light emitting device according to claim 17 , wherein the nitride semiconductor superlattice layer is disposed on a top surface of the at least one pit.