Semiconductor light emitting device including photonic band gap material and luminescent material
View Patent ↗A light emitting structure includes a semiconductor light emitting device capable of emitting first light having a first peak wavelength, a luminescent material capable of emitting second light having a second peak wavelength disposed over the semiconductor light emitting device, and a photonic band gap material disposed between the light emitting device and the luminescent material. The photonic band gap material is capable of transmitting the first light and reflecting the second light, regardless of the angle of incidence of the first and second light.
1. A structure comprising:
a semiconductor light emitting device including an active region capable of emitting first light having a first peak wavelength;
a luminescent material disposed in the path of at least a portion of the first light, wherein the luminescent material is capable of emitting second light having a second peak wavelength; and
a photonic band gap material disposed between the light emitting device and the luminescent material, wherein the photonic band gap material comprises a periodic variation in index of refraction in at least two dimensions, and wherein the photonic band gap material is capable of transmitting the first light and reflecting the second light.
2. The structure of claim 1 wherein the semiconductor light emitting device comprises at least one III-nitride layer.
3. The structure of claim 1 wherein the first light comprises light having a peak wavelength less than 490 nm.
4. The structure of claim 1 wherein the luminescent material is a phosphor.
5. The structure of claim 1 wherein the photonic band gap material contacts a surface of the semiconductor light emitting device.
6. The structure of claim 1 wherein the luminescent material contacts a surface of the photonic band gap material.
7. The structure of claim 1 wherein the photonic band gap material is spaced apart from the semiconductor light emitting device.
8. The structure of claim 1 wherein the luminescent material is spaced apart from the photonic band gap material.
9. The structure of claim 1 wherein the photonic band gap material comprises a periodic variation in index of refraction in three dimensions.
10. The structure of claim 1 wherein the photonic band gap material comprises a plurality of spheres.
11. The structure of claim 10 wherein the spheres are polystyrene.
12. The structure of claim 1 wherein the photonic band gap material comprises a plurality of material layers, each material layer including a periodic array of holes.
13. The structure of claim 12 wherein the holes are filled with air.
14. The structure of claim 12 wherein the material layers are one of crystalline, glass, and dielectric.
15. The structure of claim 12 wherein the periodic array of holes in each material layer is offset from the periodic arrays of holes in the material layers above and below.
16. The structure of claim 1 wherein the first light is blue and the second light is red or green.
17. The structure of claim 1 wherein the first light is UV and the second light is one of blue, green, and red.
18. The structure of claim 1 wherein the first light is blue and the second light is yellow.
19. The structure of claim 1 wherein:
the luminescent material absorbs a portion of the first light; and
the luminescent material is configured such that at least 90% of the first light is absorbed by the luminescent material.
20. The structure of claim 1 wherein:
the luminescent material absorbs a portion of the first light; and
the luminescent material is configured such that at least 50% of the first light is absorbed by the luminescent material.
21. The structure of claim 1 wherein the luminescent material is a first luminescent material, the structure further comprising a second luminescent material capable of emitting third light having a third peak wavelength.
22. The structure of claim 21 wherein the first light is blue, the second light is yellow or green, and the third light is red.
23. The structure of claim 21 wherein the first light is UV, the second light is blue, and the third light is yellow.
24. The structure of claim 21 further comprising a third luminescent material capable of emitting fourth light having a fourth peak wavelength, wherein the first light is UV, the second light is blue, the third light is green, and the fourth light is red.
25. The structure of claim 1 wherein the luminescent material is configured such that a portion of the first light escapes the structure without being incident on the luminescent material.
26. The structure of claim 1 wherein the photonic band gap material is capable of transmitting the first light and reflecting the second light regardless of the angle of incidence of the first and second light on the photonic band gap material.
27. The structure of claim 1 wherein the photonic band gap material is configured to transmit at least 90% of the first light incident on the photonic band gap material.
28. The structure of claim 1 wherein the photonic band gap material is configured to reflect at least 50% of the secondary light incident on the photonic band gap material.
29. The structure of claim 1 wherein the photonic band gap material is configured to reflect at least 90% of the secondary light incident on the photonic band gap material.