Light emitting device having light extraction structure and method for manufacturing the same
View Patent ↗A nitride-based light emitting device capable of achieving an enhancement in emission efficiency and an enhancement in reliability is disclosed. The light emitting device includes a semiconductor layer, and a light extracting layer arranged on the semiconductor layer and made of a material having a refractive index equal to or higher than a reflective index of the semiconductor layer.
1. A light emitting device comprising:
a reflective electrode;
a semiconductor layer over the reflective electrode, the semiconductor layer comprising a light emitting layer; and
a light extraction structure arranged on the semiconductor layer,
wherein a distance between the reflective electrode and a center of the light emitting layer falls within the ranges represented by an odd multiple of λ/(4n)±α, where “λ” represents a wavelength of light emitted from the light emitting layer, “n” represents a refractive index of the semiconductor layer, and “α” represents 0.14λ/n.
2. The light emitting device according to claim 1 , wherein the reflective electrode comprises an ohmic electrode.
3. The light emitting device according to claim 1 , wherein the reflective electrode has a reflectance of 50% or more.
4. The light emitting device according to claim 1 , wherein the light emitting layer has a thickness of 0.05λ/n to 0.25λ/n.
5. The light emitting device according to claim 1 , wherein the light extraction structure comprises holes or rods formed on the semiconductor layer.
6. The light emitting device according to claim 5 , wherein the holes have a depth of 300 to 3,000 nm, and the rods have a height of 300 to 3,000 nm.
7. The light emitting device according to claim 6 , wherein the holes or rods have a diameter of 0.25a to 0.45a where “a” represents an average periodicity of the light extraction structure.
8. The light emitting device according to claim 1 , wherein the light extraction structure has an average periodicity of 0.8 to 5 μm.
9. The light emitting device according to claim 1 further comprising:
an ohmic electrode between the reflective electrode and the semiconductor layer.
10. The light emitting device according to claim 9 , wherein the ohmic electrode comprises a transparent electrode.
11. The light emitting device according to claim 1 , wherein a p-type semiconductor layer is arranged between the reflective electrode and the light emitting layer.
12. The light emitting device according to claim 1 , wherein the reflective electrode is located over a support layer comprising a semiconductor or a metal.
13. The light emitting device according to claim 1 , wherein a distance between the reflective electrode and a center of the light emitting layer is in the range of 0.19λ/n to 0.38λ/n or 0.65λ/n to 0.93λ/n, where “λ” represents a wavelength of light emitted from the light emitting layer and “n” represents a refractive index of the semiconductor layer.
14. The light emitting device according to claim 1 , wherein the light extraction structure is formed on the semiconductor layer.
15. The light emitting device according to claim 14 , wherein the light extraction structure is formed by etching the semiconductor layer.
16. The light emitting device according to claim 1 , wherein the light extraction structure comprises the same material as that of the semiconductor layer.