LED LAMPS

• US 20120168799A1
• Filed: 01/04/2012
• Published: 07/05/2012
• Est. Priority Date: 11/19/1997
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: HASSAN, Salam P. A.
• Granted Patent: US 8,692,268 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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 high power LED lamp has a GaN chip placed over an AlGaInP chip. A reflector is placed between the two chips. Each of the chips has trenches diverting light for output. The chip pair can be arranged to produce white light having a spectral distribution in the red to blue region that is close to that of daylight. Also, the chip pair can be used to provide an RGB lamp or a red-amber-green traffic lamp. The active regions of both chips can be less than 50 microns away from a heat sink.

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.

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 of the trench.

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 of the trench 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 1, wherein the substrate comprises a non-semiconductor material.

15. The light-emitting device according to claim 1, 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.

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

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

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

19. The light-emitting device according to claim 16, wherein the heat sink has a surface adjacent to the semiconductor structure and coated with a material comprising aluminum or silver.

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

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

22. 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.

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

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

m and 20 μ

m.

25. 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.

26. The light-emitting device according to claim 7, wherein the second metallic conductor comprises metal with good reflectivity to blue light.

27. 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 thereof.

28. The light-emitting device according to claim 27, wherein the top metallic conductor is an elongated conductor.

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

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

31. The light-emitting device according to claim 30, wherein the LED chip has a width greater than 1000 μ

m.

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

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