Light emitting device and lighting apparatus having the same
A light emitting device includes a substrate including a plurality of convex portions, and a first semiconductor layer over the substrate. A plurality of first pits is provided in a top surface of the first semiconductor layer, and a plurality of second pits is provided in the top surface of the first semiconductor layer. A first metallic compound is provided in the first pits, and a second metallic compound is provided in the second pits. A second semiconductor layer is provided over the first semiconductor layer, and a light emitting structure is provided over the second semiconductor layer. The light emitting structure includes a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer.
1. A light emitting device comprising:
a substrate including a plurality of convex portions;
a first semiconductor layer provided over top surface of the substrate;
a plurality of first pits provided on a top surface of the first semiconductor layer and overlapped with the convex portions;
a plurality of second pits provided on the top surface of the first semiconductor layer and disposed in regions between the convex portions;
a first metallic compound provided in the first pits and contacted with upper portions of the convex portions;
a second metallic compound provided in the second pits;
a second semiconductor layer provided over the first semiconductor layer; and
a light emitting structure provided over the second semiconductor layer,
wherein the light emitting structure comprises a first conductive semiconductor layer on the second semiconductor layer, an active layer on the first conductive semiconductor layer, and a second conductive semiconductor layer on the active layer.
2. The light emitting device of claim 1 , wherein the first semiconductor layer includes a plurality of dislocations connected to the first and second pits, respectively.
3. The light emitting device of claim 2 , wherein the dislocations connected to the first pits progress from a vertical direction.
4. The light emitting device of claim 1 , wherein the first and second metallic compounds include an insulating material.
5. The light emitting device of claim 1 , wherein the first and second metallic compounds include nitride or oxide including silicon.
6. The light emitting device of claim 1 , wherein a lower portion of the first metallic compound includes a concave curved surface.
7. The light emitting device of claim 1 , wherein a side surface of the first metallic compound is inclined at an inclined angle equal to an inclined angle of a side surface of the first pit.
8. The light emitting device of claim 1 , wherein the first metallic compound has a lower width narrower than a lower width of each convex portion.
9. The light emitting device of claim 1 , wherein each convex portion has a hemisphere shape and a lower width of each convex portion is larger than a height of each convex portion.
10. The light emitting device of claim 1 , wherein at least one of the first and second semiconductor layers includes an n-type dopant.
11. The light emitting device of claim 1 , wherein the second pits have depths less than depths of the first pits, and are placed at positions higher than positions of the convex portions.
12. The light emitting device of claim 1 , wherein top surfaces of the first and second metallic compounds are aligned on a same horizontal plane with the top surface of the first semiconductor layer.
13. The light emitting device of claim 1 , further comprising a buffer layer between the substrate and the first semiconductor layer,
wherein a part of the buffer layer is disposed between the first metallic compound and the convex portion, and
the first metallic compound makes contact with a circumstance of a part of the buffer layer.
14. The light emitting device of claim 1 , further comprising a pore between at least one of the convex portions and the first metallic compound.
15. The light emitting device of claim 1 , wherein a dislocation density of a top surface of the second semiconductor layer is less than a dislocation density in the first semiconductor layer and is in a range of 1×10 6 cm −2 to 1×10 8 cm −2 .
16. The light emitting device of claim 1 , wherein the first and second metallic compounds comprise a material different from materials of the first and second semiconductor layers.
17. A light emitting device comprising:
a substrate including a light transparent material and including a plurality of convex portions;
a first semiconductor layer provided over the top surface of the substrate;
a plurality of first pits provided on a top surface of the first semiconductor layer and overlapped with the convex portions;
a plurality of second pits provided on the top surface of the first semiconductor layer and disposed in regions between the convex portions;
a first metallic compound provided in the first pits and contacted with upper portions of the convex portions;
a second metallic compound provided in the second pits;
a second semiconductor layer provided over the first semiconductor layer; and
a light emitting structure provided over the second semiconductor layer,
wherein the light emitting structure comprises a first conductive semiconductor layer on the second semiconductor layer, an active layer on the first conductive semiconductor layer, and a second conductive semiconductor layer on the active layer,
the first and second metallic compounds comprise a material different from materials of the first and second semiconductor layers, and
each first metallic compound has a volume greater than a volume of each second metallic compound.
18. The light emitting device of claim 16 , wherein the first semiconductor layer has a thickness larger than a height of each convex portion, and
the first pits have depths deeper than depths of the second pits.
19. A light emitting device comprising:
a substrate including a light transparent material and including a plurality of convex portions;
a plurality of protrusions protruding from a bottom surface of the substrate;
a first semiconductor layer provided over the top surface of the substrate;
a plurality of first pits provided on a top surface of the first semiconductor layer and overlapped with the convex portions;
a plurality of second pits provided on the top surface of the first semiconductor layer and disposed in regions between the convex portions;
a first metallic compound provided in the first pits and contacted with upper portions of the convex portions;
a second metallic compound provided in the second pits;
a second semiconductor layer provided over the first semiconductor layer; and
a light emitting structure over the second semiconductor layer,
wherein the light emitting structure comprises a first conductive semiconductor layer on the second semiconductor layer, an active layer on the first conductive semiconductor layer, and a second conductive semiconductor layer on the active layer,
the first and second metallic compounds comprise a material different from materials of the first and second semiconductor layers,
each first metallic compound has a volume greater than a volume of each second metallic compound, and
the first metallic compound includes top surfaces having horizontal surfaces aligned on a same horizontal plane with the top surface of the first semiconductor layer and side surfaces inclined at the same angle as a side surface of the first pit.
20. The light emitting device of claim 19 , wherein the first metallic compound includes a plurality of inclined side surfaces making contact with the first semiconductor layer, and a concave bottom surface making contact with surfaces the convex portions.