Light emitting device
A light emitting device includes a substrate and a light emitting structure including a first conductive type semiconductor layer, an active layer and a second conductive type semiconductor layer provided in a first direction on the substrate. A first electrode layer is provided over the first conductive type semiconductor layer, and a second electrode layer is provided in a second direction over the second conductive type semiconductor layer. The second electrode layer has an energy band gap wider than an energy band gap of the active layer.
1. A light emitting device, comprising:
a substrate;
a light emitting structure comprising a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer provided on the substrate;
a first electrode layer provided over the first conductive type semiconductor layer;
and
a second electrode layer provided over the second conductive type semiconductor layer, the second electrode layer having an energy band gap wider than an energy band gap of the active layer,
wherein the second electrode layer and the second conductive type semiconductor layer form an integrated single layer structure,
wherein an energy band gap of the second electrode layer is the same as an energy band gap of the second conductive type semiconductor layer,
wherein the second conductivity type semiconductor layer comprises a semiconductor material containing aluminum, and
wherein aluminum contained in the second conductive type semiconductor layer has a concentration gradient which increases as a distance from the active layer increases.
2. The light emitting device according to claim 1 , further comprising:
a submount;
first and second electrode pads provided over the submount; and
first and second bumps to couple the first and second electrode layers to the first and second electrode pads, respectively.
3. The light emitting device according to claim 1 , wherein the second electrode layer has a thickness of 10 nm to 1,000 nm.
4. The light emitting device according to claim 1 , wherein the second electrode layer has a light extraction pattern.
5. The light emitting device according to claim 4 , wherein the light extraction pattern has at least one of a secondary prism shape, a hemispheral shape, a conic shape, a truncated shape, a hexahedral shape, a cylindrical shape, a protrusion shape, groove shape, a bar shape, or a lattice shape.
6. The light emitting device according to claim 1 , wherein light emitted from the active layer is deep ultraviolet or ultraviolet light.
7. The light emitting device according to claim 1 , wherein the second electrode layer includes an ohmic-contacting material.
8. The light emitting device according to claim 1 , wherein at least one of the second conductive type semiconductor layer and the second electrode layer comprises at least one material of AlN and BN.
9. The light emitting device according to claim 1 , wherein the second electrode layer comprises at least one of oxygen (O 2 ) and carbon (C), and a second conductive type dopant doped together therewith.
10. The light emitting device according to claim 1 , wherein the concentration gradient is nonlinear.
11. The light emitting device according to claim 1 , wherein the concentration gradient is linear.
12. The light emitting device according to claim 1 , wherein the aluminum has a content of 50% to 100%.
13. The light emitting device according to claim 1 , wherein the second conductive type semiconductor layer has a thickness of 10 nm to 100 nm.
14. The light emitting device according to claim 1 , wherein the second conductive type semiconductor layer has a single layer or multilayer structure.
15. The light emitting device according to claim 1 , further comprising a separate ohmic layer disposed on the second electrode layer.