Selective placement of quantum wells in flipchip light emitting diodes for improved light extraction
View Patent ↗In accordance with embodiments of the invention, a light emitting device includes a light emitting region and a reflective contact separated from the light emitting region by one or more layers. In a first embodiment, the separation between the light emitting region and the reflective contact is between about 0.5λ n and about 0.9λ n , where λ n is the wavelength of radiation emitted from the light emitting region in an area of the device separating the light emitting region and the reflective contact. In a second embodiment, the separation between the light emitting region and the reflective contact is between about λ n and about 1.4λ n . The light emitting region may be, for example, III-nitride, III-phosphide, or any other suitable material.
1. A light emitting diode comprising:
a light emitting region capable of emitting radiation; and
a reflector reflective of the radiation and separated from the light emitting region by a separation, wherein the separation is such that interferences between direct and reflected beams of the emitted radiation cause radiation to concentrate in a top escape cone of the light emitting device.
2. The light emitting diode of claim 1 wherein the radiation is concentrated in a top escape cone of the light emitting device, but not on a central perpendicular axis of the light emitting region.
3. A light emitting diode comprising:
a light emitting region capable of emitting radiation; and
a reflector reflective of the radiation;
wherein the reflector is separated from the light emitting region by a separation ranging between about 0.5λ n about 0.9λ n , wherein λ n is the wavelength of the radiation within a region separating the light emitting region from the reflector.
4. The light emitting diode of claim 3 wherein the reflector comprises silver and nickel.
5. The light emitting diode of claim 4 wherein the light emitting region comprises Al x In y Ga z N, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1.
6. The light emitting diode of claim 4 wherein the separation is between about 0.6λ n and about 0.75λ n .
7. The light emitting diode of claim 4 wherein:
the radiation has a wavelength of 450 nm in a vacuum; and
the separation is between about 93.8 nm and about 150.0 nm.
8. The light emitting diode of claim 4 wherein:
the radiation has a wavelength of 505 nm in a vacuum; and
the separation is between about 111.5 nm and about 174.6 nm.
9. The light emitting diode of claim 4 wherein:
the radiation has a wavelength of 530 nm in a vacuum; and
the separation is between about 121.5 nm and about 187.7 nm.
10. The light emitting diode of claim 3 wherein the reflector comprises silver.
11. The light emitting diode of claim 10 wherein the light emitting region comprises Al x In y Ga z N, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1.
12. The light emitting diode of claim 10 wherein the separation is between about 0.65λ n and about 0.754λ n .
13. The light emitting diode of claim 3 wherein the reflector comprises one of gold and gold alloy.
14. The light emitting diode of claim 13 wherein the light emitting region comprises Al x In y Ga z P, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1.
15. The light emitting diode of claim 13 wherein the separation is between about 0.6λ n and about 0.75λ n .
16. The light emitting diode of claim 3 wherein the reflector has a reflectance greater than 80%.
17. The light emitting diode of claim 3 wherein the reflector has a reflectance greater than 90%.
18. The light emitting diode of claim 3 wherein the light emitting region comprises a plurality of quantum wells.
19. The light emitting diode of claim 18 wherein the separation is from a center of brightness of the plurality of quantum wells to the reflector.
20. The light emitting diode of claim 3 further comprising:
a region of first conductivity type near a first side of the light emitting region;
a region of second conductivity type near a second side of the light emitting region;
a first contact electrically connected to the region of first conductivity type;
a second contact electrically connected to the region of second conductivity type; and
a submount electrically connected to the first and second contacts.
21. The light emitting diode of claim 20 further comprising a lens overlying the light emitting region.
22. A light emitting diode comprising:
a light emitting region capable of emitting radiation; and
a reflector reflective of the radiation;
wherein the reflector is separated from the light emitting region by a separation ranging between about λ n and about 1.4λ n , wherein λ n is the wavelength of the radiation within a region separating the light emitting region from the reflector.
23. The light emitting diode of claim 22 wherein:
the reflector comprises silver and nickel;
the light emitting region comprises Al x In y Ga z N, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1; and
the separation is between about 1.05λ n and about 1.4λ n .
24. The light emitting diode of claim 23 wherein the separation is between about 1.15λ n and about 1.3λ n .
25. The light emitting diode of claim 23 wherein:
the radiation has a wavelength of 450 nm in a vacuum; and
the separation is between about 196.9 nm and about 253.1 nm.
26. The light emitting diode of claim 23 wherein:
the radiation has a wavelength of 505 nm in a vacuum; and
the separation is between about 227.3 nm and about 290.4 nm.
27. The light emitting diode of claim 23 wherein:
the radiation has a wavelength of 530 nm in a vacuum; and
the separation is between about 242.9 nm and about 309.2 nm.
28. The light emitting diode of claim 22 wherein:
the reflector comprises silver;
the light emitting region comprises Al x In y Ga z N, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1; and
the separation is between about 1.15λ n and about 1.38λ n .
29. The light emitting diode of claim 22 wherein:
the reflector comprises one of gold and gold alloy;
the light emitting region comprises Al x In y Ga z P, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1; and
the separation is between about 1.1λ n and about 1.25λ n .
30. The light emitting diode of claim 22 wherein the light emitting region comprises a plurality of quantum wells.
31. The light emitting diode of claim 30 wherein the separation is from a center of brightness of the plurality of quantum wells to the reflector.
32. A light emitting diode comprising:
a light emitting region capable of emitting radiation; and
a reflector reflective of the radiation;
wherein the reflector is separated from the light emitting region by a separation ranging between about 1.55λ n and about 1.95λ n , wherein λ n is the wavelength of the radiation within a region separating the light emitting region from the reflector.
33. The light emitting diode of claim 32 wherein:
the reflector comprises silver and nickel;
the light emitting region comprises Al x In y Ga z N, wherein 0 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1; and
the separation is between about 1.65λ n and about 1.8λ n .
34. The light emitting diode of claim 32 wherein:
the reflector comprises silver;
the light emitting region comprises Al x In y Ga z N, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1; and
the separation is between about 1.73λ n and about 1.85λ n .
35. The light emitting diode of claim 32 wherein:
the reflector comprises one of gold and gold alloy;
the light emitting region comprises Al x In y Ga z P, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1; and
the separation is between about 1.6λ n and about 1.8λ n .
36. A light emitting diode comprising:
a light emitting region capable of emitting radiation; and
a reflector reflective of the radiation, the reflector comprising one of gold and gold alloy;
wherein the reflector is separated from the light emitting region by a separation ranging between about 2.12λ n and about 2.3λ n , wherein λ n is the wavelength of the radiation within a region separating the light emitting region from the reflector.