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 method for manufacturing a light emitting device, the method comprising:
applying a mask layer on a dielectric layer on a semiconductor layer;
forming a pattern into the mask layer, the pattern comprising unit structures,
wherein the unit structures have a hole or a rod shape, and
wherein a wall of the unit structures is sloped at an angle of −45° to +45°, from a virtual vertical line parallel to a light emitting direction of the light emitting device;
forming a light extraction structure into the dielectric layer using the mask layer; and
controlling an average filling factor of the pattern by adjusting at least one of a slope of the wall, a radius of the unit structures, and a lattice structure of the light extraction structure,
wherein the average filling factor of the light extraction structure is more than 5% and less than 37% with respect to an area of a light emission surface of the light emitting device, and
wherein the average filling factor is a ratio of an average area of the pattern with respect to a total area of a light emission surface of the light emitting device.
2. The method according to claim 1 , wherein the semiconductor layer comprises GaN.
3. The method according to claim 1 , wherein the step of forming the pattern comprises:
forming the pattern using photolithography.
4. The method according to claim 3 , wherein a distance between centers of neighboring unit structures of the pattern is 1˜10 times a wavelength of irradiated light.
5. The method 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.
6. The method according to claim 1 , wherein a period of the light extraction structure or an average distance between centers of neighboring unit structures is more than 3,000 nm.
7. The method according to claim 1 , wherein a height of the unit structures is λ/2n˜3,000 nm, “n” representing a refraction index of a material of the light extraction structure, and λ representing a central wavelength of the light emitting device.
8. The method according to claim 1 , wherein the unit structures has a truncated shape.
9. The method according to claim 1 , wherein the light extraction structure comprises 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.
10. The method according to claim 1 , wherein a slope of the wall of the unit structures is configured to enhance a light extraction efficiency of the light emitting device.
11. The method according to claim 1 , wherein a light emission surface of the light emitting device is formed as a horizontally sectional virtual surface below the light extraction structure.
12. The method according to claim 1 , wherein the mask layer comprises a photoresist.
13. The method according to claim 1 , wherein the dielectric layer contacts the semiconductor layer.
14. A method for manufacturing a light emitting device, the method comprising:
applying a mask layer on a light extraction layer;
forming a pattern into the mask layer, the pattern comprising unit structures,
wherein the unit structures have a hole or a rod shape, and
wherein a wall of the unit structures is sloped at an angle of −45° to +45° from a virtual vertical line parallel to a light emitting direction of the light emitting device; and
forming a light extraction structure into the light extraction layer using the mask layer,
wherein an average filling factor of the light extraction structure is more than 5% and less than 37% with respect to an area of a light emission surface of the light emitting device, and
wherein the average filling factor is a ratio of an average area of the pattern with respect to a total area of a light emission surface of the light emitting device.