Light emitting device having light extraction structure
View Patent ↗A light emitting device having a light extraction structure, which is capable of achieving an enhancement in light extraction efficiency and reliability, and a method for manufacturing the same. The light emitting device includes a semiconductor layer having a multi-layered structure including a light emission layer; and a light extraction structure formed on the semiconductor layer in a pattern having unit structures. Further, the wall of each of the unit structures is sloped at an angle of −45° to +45° from a virtual vertical line being parallel to a main light emitting direction of the light emitting device.
1. A light emitting device, comprising:
a substrate;
a bonding layer on the substrate;
a first electrode on the bonding layer;
a semiconductor structure comprising a light emission layer and a light extraction structure on the first electrode; and
a second electrode,
wherein the first and second electrodes are electrically connected to the semiconductor structure,
wherein the light extraction structure includes a unit structure having a hole or rod shape and having a beveled wall,
wherein a slope of the beveled wall is configured such that an average filling factor of the light extraction structure is more than 5% and less than 37% with respect to an area of a main light emission surface of the semiconductor structure, and
wherein the main light emission surface is a horizontally sectioned, virtual surface below the light extraction structure.
2. The light emitting device according to claim 1 , wherein a period of the light extraction structure or an average distance between centers of neighboring unit structures is 400˜3,000 nm.
3. The light emitting device according to claim 1 , wherein a period of the light extraction structure or an average distance between centers of the neighboring unit structures is more than 3,000 nm.
4. The light emitting device according to claim 1 ,
wherein a height of the unit structure is λ/2n˜3,000 nm, and
wherein “n” represents a refraction index of a material of the light extraction structure, and λ represents a central wavelength of the light emission layer.
5. The light emitting device according to claim 1 , wherein the light extraction structure is arranged on the light emission layer.
6. The light emitting device according to claim 1 , wherein the unit structure has a truncated shape.
7. The light emitting device according to claim 1 , wherein the light extraction structure is one of a rectangular lattice structure, a triangular lattice structure, an Archimedean lattice structure, a random structure, a Quasi-crystal structure, and a Quasi-random structure.
8. The light emitting device according to claim 1 , wherein the slope of beveled wall is an angle of −45° to +45° (excluding 0°) from a virtual vertical line perpendicular to the main light emission surface.
9. The light emitting device according to claim 1 ,
wherein the semiconductor structure includes a first-type semiconductor layer and a second-type semiconductor layer, and
wherein the light emission layer is arranged between the first-type semiconductor layer and the second-type semiconductor layer.
10. The light emitting device according to claim 9 , wherein an area of the first-type semiconductor layer facing the light emission layer is substantially the same as an area of the second-type semiconductor layer facing the light emission layer.
11. The light emitting device according to claim 1 , wherein the substrate comprises a metal or a semiconductor.
12. The light emitting device according to claim 1 , wherein the substrate comprises a conductive material.
13. The light emitting device according to claim 1 , wherein the first electrode comprises a reflective electrode.
14. The light emitting device according to claim 1 , further comprising:
a diffusion barrier layer between the first electrode and the bonding layer.
15. The light emitting device according to claim 1 , wherein the bonding layer comprises a metal layer.
16. The light emitting device according to claim 1 , wherein the second electrode is arranged on the semiconductor structure.
17. The light emitting device according to claim 16 , wherein the second electrode contacts the light extraction structure.
18. The light emitting device according to claim 1 , wherein the first and second electrodes are located on opposite surfaces of the semiconductor structure.
19. The light emitting device according to claim 1 , wherein the bonding layer contacts the substrate.
20. The light emitting device according to claim 1 , wherein the slope of the beveled wall is configured to enhance a light extraction efficiency of the light emitting device.