High power allngan based multi-chip light emitting diode

• US 8,502,239 B2
• Filed: 11/10/2005
• Issued: 08/06/2013
• Est. Priority Date: 05/13/2003
• Status: Active Grant

• Current Assignee: BX LED LLC (IPValuation Partners, LLC)
• Original Assignee: Bridgelux Incorporated
• Inventors: Liu, Heng
• Primary Examiner(s): Landau, Matthew
• Assistant Examiner(s): Kim, Sun M
• Application Number:
  US11/272,366
• Publication Number:
  US 20060063288A1
• Time in Patent Office: 2,826 Days
• Field of Search: 257/E33.006, 257/E33.068, 257/E33.072, 257/98, 257/88, 257E33056-E33059, 372/66
• US Class Current: 257/88
• CPC Class Codes: F21L 4/027 the light sources being a LED
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A light emitting diode chip having a substantially transparent substrate and having an aspect ratio, which defines an elongated geometry provides enhanced efficiency and brightness. Method for forming and operating the same are also disclosed.

Claims

1. A lamp, comprising:

a plurality of light emitting diode chips, each comprising

a substrate;

a lower epitaxial layer formed upon the substrate;

an upper epitaxial layer, formed upon the lower epitaxial layer to expose a portion of the lower epitaxial layer;

an upper contact finger formed upon the upper epitaxial layer;

a lower contact finger formed upon the exposed portion of the lower epitaxial layer, generally parallel to a length of the lower epitaxial layer, wherein the upper and lower epitaxial layers cooperate to form a generally planar active area, a ratio of a length of the active area to a width of the active area is at least 1.5;

1, and the width of the active area is at least 250 microns; and

a reflective material intermediate the lower contact finger and the upper epitaxial layer to direct light away from the lower contact finger; and

a package having a recess defined by a bottom surface and four sidewalls in which pairs of sidewalls are generally co-parallel and intersect to define four corners of the recess, the plurality of diode chips disposed in the recess, and are arranged around the periphery of the recess, with lengths of the diode chips co-parallel to the sidewalls, and each end of each of the diode chips disposed around the periphery of the recess either abut one of the corners of the recess, or abut an edge of another diode chip arranged around the periphery of the recess, and one or more of the plurality of light emitting diode chips are indirectly coupled to receive a biasing voltage from a pair of bonding wires respectively connected to different light emitting diode chips of the plurality.

2. The lamp of claim 1, wherein the reflective material comprises a reflecting insulator material.

3. The lamp of claim 1, wherein the reflective material comprises an insulator material, and a metallic material electrically shielded from the upper epitaxial layer by the insulator material.

4. The lamp of claim 1, wherein the upper epitaxial layer and the lower epitaxial layer have an elongated geometry.

5. The lamp of claim 4, wherein the lower contact finger is disposed generally parallel to a longer side of the lower epitaxial region.

6. The lamp of claim 4, wherein the elongated geometry provides an active region having a length to width ratio of at least 2:

1.

7. The lamp of claim 4, wherein the elongated geometry provides an active region having a length to width ratio of at least 2:

1 and less than 10;

1.

8. The lamp of claim 1, wherein the reflective material comprises a transparent insulator material and a metallic reflecting material electrically shielded from the upper epitaxial layer by the insulator material.

9. The lamp of claim 1, wherein the lower epitaxial layer comprises an n-doped layer.

10. The lamp of claim 1, wherein the upper epitaxial layer comprises a p-doped layer.

11. The lamp of claim 1, wherein the upper contact finger comprises a bond pad portion.

12. The lamp of claim 1, further comprising a bond pad in electrical contact with the upper contact finger.

13. The lamp of claim 1, wherein the lower contact finger comprises a bond pad portion.

14. The lamp of claim 1, further comprising a bond pad in electrical contact with the lower contact finger.

15. The lamp of claim 1, wherein one light emitting diode is formed upon the substrate.

16. The lamp of claim 1, wherein the substrate comprises a material selected from the group consisting of:

sapphire;

spinel;

glass;

ZnO;

SiC;

MgO;

GaN;

MN; and

AlGaN.

17. The lamp of claim 1, wherein an active region is formed so as to cover substantially all of the substrate that is not covered by the lower epitaxial layer, the reflective material, or the lower contact finger.

18. The lamp of claim 1, wherein the package further comprises a reflective protrusion disposed centrally in the recess and configured for reflecting light from the package.