Horizontal light emitting diodes including phosphor particles

• US 9,640,737 B2
• Filed: 01/31/2011
• Issued: 05/02/2017
• Est. Priority Date: 01/31/2011
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Donofrio, Matthew, Edmond, John Adam, Ibbetson, James, Emerson, David Todd, Bergmann, Michael John, Haberern, Kevin, Rosado, Raymond, Britt, Jeffrey Carl
• Primary Examiner(s): Nadav, Ori
• Application Number:
  US13/018,013
• Publication Number:
  US 20120193660A1
• Time in Patent Office: 2,283 Days
• Field of Search: 257 79- 81, 257 98-100
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body

Abstract

Horizontal light emitting diodes include anode and cathode contacts on the same face and a transparent substrate having an oblique sidewall. A conformal phosphor layer having an average equivalent particle diameter d50 of at least about 10 μm is provided on the oblique sidewall. High aspect ratio substrates may be provided. The LED may be directly attached to a submount.

Claims

1. A light emitting diode comprising:

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer;

an anode contact that ohmically contacts the p-type layer and extends on the first face;

a cathode contact that ohmically contacts the n-type layer and that also extends on the first face;

a transparent substrate on the second face, the transparent substrate including an inner face adjacent the second face, an outer face remote from the second face and a sidewall that extends from the outer face to the inner face; and

a conformal layer that comprises phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m, on the outer face and extending on the sidewall oblique to the inner face.

2. A light emitting diode according to claim 1 wherein the conformal layer that comprises phosphor has an average equivalent particle diameter d50 of about 15 μ

m.

3. A light emitting diode according to claim 1 wherein the conformal layer that comprises phosphor has an average equivalent particle diameter d50 of between about 15 μ

m and about 17 μ

m.

4. A light emitting diode according to claim 1 wherein the conformal layer that comprises phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m is of uniform thickness on the outer face and on the sidewall.

5. A light emitting diode according to claim 1 wherein the diode region is configured to emit blue light upon energization thereof and wherein the conformal layer comprises yellow phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m.

6. A light emitting diode according to claim 1 wherein the diode region is configured to emit blue light upon energization thereof and wherein the conformal layer comprises a mixture of yellow phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m and red phosphor.

7. A light emitting diode according to claim 1 wherein the conformal layer comprises a mixture of yellow phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m and red phosphor, in a phosphor weight ratio of the yellow phosphor to the red phosphor of at least about 5;

1.

8. A light emitting diode according to claim 1 wherein the conformal layer comprises a mixture of yellow phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m and red phosphor in a phosphor weight ratio of the yellow phosphor to the red phosphor of at least about 9;

1.

9. A light emitting diode according to claim 1 wherein the anode and cathode contacts that both extend on the first face are coplanar.

10. A light emitting diode according to claim 1 in combination with a submount having a submount face and an anode pad and a cathode pad thereon, the light emitting diode being mounted on the submount such that the first face is adjacent the submount face, the outer face is remote from the submount, the anode contact is adjacent the anode pad and the cathode contact is adjacent the cathode pad.

11. A light emitting diode according to claim 10 wherein the anode contact is mounted directly on the anode pad and the cathode contact is mounted directly on the cathode pad.

12. A light emitting diode according to claim 10 in further combination with a lens that extends from the submount face to surround the light emitting diode.

13. A light emitting diode according to claim 10 wherein the conformal layer that comprises phosphor having an average equivalent particle diameter d50 of between about 10 μ

m and about 20 μ

m also extends onto the submount face.

14. A light emitting diode according to claim 13 wherein the submount includes a reflective layer thereon that extends between the submount face and the conformal layer that comprises phosphor that extends on the submount face.

15. A light emitting diode according to claim 1 wherein the cathode contact and the anode contact collectively occupy at least about 90% of an active area of the diode region.

16. A light emitting diode according to claim 1 wherein the inner and outer faces define a height therebetween and wherein a ratio of the height to a side of the inner face is at least about 0.3.

17. A light emitting diode according to claim 1 wherein an area ratio of the outer face to the inner face is less than or about 0.33.

18. A light emitting diode according to claim 17 wherein the inner and outer faces define a height therebetween and wherein a ratio of the height to a side of the inner face is at least about 0.4.

19. A light emitting diode according to claim 1 wherein an area ratio of the outer face to the inner face is less than or about 0.04.

20. A light emitting diode according to claim 19 wherein the inner and outer faces define a height therebetween and wherein a ratio of the height to a side of the inner face is at least about 0.8.

21. A light emitting diode according to claim 1 wherein the substrate includes a groove therein at the outer face.

22. A light emitting diode according to claim 5 wherein the light emitting diode is configured to produce a maximum variation of Correlated Color Temperature of less than or about 3,000.

23. A light emitting diode according to claim 5 wherein the light emitting diode is configured to produce a maximum variation of Correlated Color Temperature of less than or about 2,000.

24. A light emitting diode according to claim 6 wherein the light emitting diode is configured to produce a maximum variation of Correlated Color Temperature of less than or about 1,000.

25. A light emitting diode according to claim 6 wherein the light emitting diode is configured to produce a maximum variation of Correlated Color Temperature of less than or about 500.

26. A light emitting diode according to claim 6 wherein the light emitting diode is configured to produce a maximum variation of Correlated Color Temperature of less than or about 300.

27. A light emitting diode according to claim 1 wherein an area ratio of the outer face to the inner face is less than or about 0.4.

28. A light emitting diode according to claim 1 wherein the outer face is of smaller area than the inner face and wherein the sidewall is an oblique sidewall that extends at an oblique angle from the outer face towards the inner face.