Light emitting devices with improved light extraction efficiency

• US 7,009,213 B2
• Filed: 07/31/2003
• Issued: 03/07/2006
• Est. Priority Date: 07/31/2003
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Harbers, Gerard, Martin, Paul S., Steranka, Frank M., Camras, Michael D., Imler, William R., Tichy, Ladislav, Ticha, Helena, Pocius, Douglas W., West, R. Scott, Keuper, Matthijs H.
• Primary Examiner(s): TRAN, MINH LOAN
• Application Number:
  US10/633,054
• Publication Number:
  US 20050023545A1
• Time in Patent Office: 950 Days
• Field of Search: 257 98-100, 372/50, 362/327, 362/308, 362/337, 362/336, 362/296, 362339-341
• US Class Current: 257/98
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A device includes a light emitting semiconductor device bonded to an optical element. In some embodiments, the optical element may be elongated or shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element. In some embodiments, the semiconductor light emitting device and optical element are positioned in a reflector or adjacent to a light guide. The optical element may be bonded to the first semiconductor light emitting device by a bond at an interface disposed between the optical element and the semiconductor light emitting device. In some embodiments, the bond is substantially free of organic-based adhesives.

Claims

1. A device comprising:

a semiconductor light emitting device comprising a stack of semiconductor layers including an active region; and

an optical element bonded to the semiconductor light emitting device by a bond disposed at an interface between the optical element and the semiconductor light emitting device;

wherein the optical element is shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element.

2. The device of claim 1 wherein the optical element comprises a wedge comprising:

a first surface adjacent to the bond connecting the optical element to the semiconductor light emitting device;

a substantially flat second surface substantially perpendicular to the first surface; and

a substantially flat third surface connecting the first and second surfaces.

3. The device of claim 2 further comprising a mirror adjacent to at least a portion of the third surface.

4. The device of claim 1 wherein the optical element comprises:

a first surface adjacent to the bond connecting the optical element to the semiconductor light emitting device;

a substantially flat second surface substantially perpendicular to the first surface; and

a curved third surface.

5. The device of claim 4 further comprising a mirror adjacent to at least a portion of the third surface.

6. The device of claim 4 wherein the curved third surface connects the first and second surface.

7. The device of claim 4 wherein the curved third surface curves downward from the second surface toward a point on a central axis of the optical element and semiconductor light emitting device.

8. The device of claim 1 wherein a cross section of the optical element is thinner in a central region than in a peripheral region.

9. The device of claim 1 wherein a surface of the optical element comprises a reflector.

10. The device of claim 9 wherein the reflector is selected from the group of a metallization, a dielectric layer, a reflective coating, and a total internal reflector.

11. The device of claim 1 wherein said bond is substantially free of organic-based adhesive.

12. The device of claim 1 wherein the optical element is elongated.

13. The device of claim 12 wherein the optical element comprises a rectangular slab.

14. The device of claim 1 wherein said bond comprises a bonding layer.

15. The device of claim 1 wherein the optical element is directly bonded to a surface of the semiconductor light emitting device.

16. The device of claim 1 wherein the semiconductor light emitting device comprises a substrate, wherein a surface of the semiconductor light emitting device bonded to the optical element is a surface of the substrate.

17. The device of claim 1 wherein the semiconductor light emitting device comprises a metal contact, wherein a surface of the semiconductor light emitting device bonded to the optical element is a surface of the metal contact.

18. The device of claim 1 wherein a surface of the semiconductor light emitting device bonded to the optical element is a surface of the stack of semiconductor layers.