LED lamps

• US 8,692,268 B2
• Filed: 01/04/2012
• Issued: 04/08/2014
• Est. Priority Date: 11/19/1997
• Status: Expired due to Fees

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Hassan, Salam
• Primary Examiner(s): STARK, JARRETT J
• Application Number:
  US13/343,267
• Publication Number:
  US 20120168799A1
• Time in Patent Office: 825 Days
• Field of Search: 257/94, 257/99, 257/E33.062, 257/91, 257/96
• US Class Current: 257/94
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: H01L 2224/4824 Connecting between the body and an opposite side of the item with respect to the body
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A light-emitting device for generating incoherent light comprises a substrate, a semiconductor structure, and a first metallic conductor formed on the substrate. The semiconductor structure comprises a top face, a bottom face, outer side faces, a first light-emitting part, a second light-emitting part, and light-extraction surfaces arranged for harvesting light from the semiconductor structure and being distant from the outer side faces. Each of the first and second light-emitting parts comprises a lower semiconductor layer on the substrate, an upper semiconductor layer on the lower semiconductor layer, and an active region between the lower and upper semiconductors for generating light. The first metallic conductor electrically connects the upper semiconductor layer of the first light-emitting part with the lower semiconductor layer of the second light-emitting part. The substrate comprises a non-semiconductor material.

Claims

1. A light-emitting device for generating incoherent light, comprising:

a substrate;

a semiconductor structure, formed on the substrate, comprising a top face, a bottom face, outer side faces, a first light-emitting part, a second light-emitting part, and light-extraction surfaces arranged for harvesting light from the semiconductor structure and being distant from the outer side faces; and

a first metallic conductor;

wherein each of the first and second light-emitting parts comprises a lower semiconductor layer on the substrate, an upper semiconductor layer on the lower semiconductor layer, and an active region between the lower and upper semiconductors for generating light;

wherein the first metallic conductor electrically connects the upper semiconductor layer of the first light-emitting part with the lower semiconductor layer of the second light-emitting part;

wherein the substrate comprises a non-semiconductor material.

2. The light-emitting device according to claim 1, further comprising a trench extending from the top face into the semiconductor structure.

3. The light-emitting device according to claim 2, wherein the trench extends from the top face into the substrate and isolates the first light-emitting part from the second light-emitting part.

4. The light-emitting device according to claim 2, wherein the light-extraction surfaces comprises inclined sidewalls.

5. The light-emitting device according to claim 3, wherein the trench defines boundaries of the first and second light-emitting parts, and is elongated along the boundaries.

6. The light-emitting device according to claim 3, further comprising a transparent dielectric on the trench and between the first metallic conductor and the semiconductor structure.

7. The light-emitting device according to claim 2, further comprising a second metallic conductor on a bottom of the trench for energizing the lower semiconductor layer of the light-emitting structure.

8. The light-emitting device according to claim 7, wherein the trench is an elongated trench;

and the second metallic conductor is an elongated metallic conductor.

9. The light-emitting device according to claim 7, further comprising light-generating portions arranged on opposite sides of the second metallic conductor, and the second metallic conductor is electrically common to the light-generating portions.

10. The light-emitting device according to claim 7, wherein the lower semiconductor layer under the second metallic conductor has a thickness greater than 5% of a total thickness of the lower semiconductor layer.

11. The light-emitting device according to claim 2, wherein the trench extends from the top face into the semiconductor structure by more than 50% of a thickness of the semiconductor structure.

12. The light-emitting device according to claim 9, wherein the light extraction surfaces comprises inclined sidewalls between light-generating portions.

13. The light-emitting device according to claim 1, wherein the substrate is transparent to light generated in the semiconductor structure.

14. The light-emitting device according to claim 2, wherein the trench is filled with a transparent dielectric material having a refractive index that is less than 80% of the refractive index of the semiconductor structure.

15. The light-emitting device according to claim 1, further comprising a heat sink that is less than 50 microns away from the active region.

16. The light-emitting device according to claim 15, wherein the heat sink comprises aluminum.

17. The light-emitting device according to claim 15, wherein the heat sink comprises CuW.

18. The light-emitting device according to claim 15, wherein the heat sink has a surface adjacent to the semiconductor structure and coated with a material comprising aluminum or silver.

19. The light-emitting device according to claim 1, wherein the first and second light-emitting parts are connected in series.

20. The light-emitting device according to claim 1, wherein the semiconductor structure is grown on the substrate.

21. The light-emitting device according to claim 1, wherein one of the light-extraction surfaces forms an obtuse angle with the top face of the semiconductor structure.

22. The light-emitting device according to claim 21, wherein the obtuse angle is between 95 degree and 130 degree.

23. The light-emitting device according to claim 7, wherein the second metallic conductor has a width between 5 μ

m and 20 μ

m.

24. The light-emitting device according to claim 7, wherein the second metallic conductor is an opaque conductor having a thickness of 0.5 μ

m or more.

25. The light-emitting device according to claim 1, further comprising a top metallic conductor having a thickness of 0.2 μ

m or more, and formed on the upper semiconductor layer of the first light-emitting part, the upper semiconductor layer of the second light-emitting part, or both.

26. The light-emitting device according to claim 25, wherein the top metallic conductor is an elongated conductor.

27. The light-emitting device according to claim 25, further comprising a non-semiconductor light-passing layer between the top metallic conductor and the upper semiconductor layer.

28. The light-emitting device according to claim 1, wherein the light-emitting device is an LED chip.

29. The light-emitting device according to claim 28, wherein the LED chip has a width greater than 1000 μ

m.

30. The light-emitting device according to claim 1, further comprising a lens on the semiconductor structure.

31. The light-emitting device according to claim 1, further comprising a fluorescent material on the semiconductor structure.

32. The light-emitting device according to claim 28, wherein the LED chip has a size greater than 1 mm square, and the input power rating of the chip exceeds 150 milliwatts.

33. The light-emitting device according to claim 1, wherein the active region comprises nitride of at least one of gallium, indium, and aluminum, and the substrate comprises sapphire.