Light-emitting diode with planar omni-directional reflector

• US 6,784,462 B2
• Filed: 12/12/2002
• Issued: 08/31/2004
• Est. Priority Date: 12/13/2001
• Status: Expired due to Term

• Current Assignee: Rensselaer Polytechnic Institute
• Original Assignee: Rensselaer Polytechnic Institute
• Inventors: Schubert, E. Fred
• Primary Examiner(s): Tran, Minhloan
• Assistant Examiner(s): TRAN, TAN N
• Application Number:
  US10/317,564
• Publication Number:
  US 20030111667A1
• Time in Patent Office: 628 Days
• Field of Search: 257/98, 257/94, 257/97, 257/99, 257/91, 257/103, 257/95, 257/96, 257/22, 257/79, 257/85, 257/90, 257/12, 257/13
• US Class Current: 257/98
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

A high extraction efficiency, light-emitting diode having a reflective submount and methods for forming the LED. A light-emitting region is disposed between a top contact and a conductive holder. The region extends beyond an area underlying the top contact. An omni-directional reflector is disposed between the light-emitting region and the conductive holder. According to one embodiment, the reflector comprises one or more electrically conductive contacts configured to correspond to an area beyond the area underlying the top contact. According to one embodiment, the reflector comprises a dielectric layer having a refractive index of between about 1.10 and 2.25, contacts extending through the reflector, and a reflective conductive film.

Claims

1. A light-emitting diode comprising:

a top contact

a conductive holder;

a light-emitting region disposed between the top contact and the conductive holder including an area underlying the top contact and another area extending beyond the area underlying the top contact; and

an omni-directional reflector disposed between the light-emitting region and the conductive holder, the omni-directional reflector having a plurality electrically conductive contacts configured to correspond to a region beyond the area underlying the top contact, wherein the plurality of electrically conductive contacts are disposed in a dielectric layer, the dielectric layer having a reflective index of between about 1.10 and 2.25.

2. The light-emitting diode of claim 1 wherein the dielectric layer comprises silicon dioxide.

3. The light-emitting diode of claim 1 wherein the dielectric layer comprises silicon nitride.

4. The light-emitting diode of claim 1 wherein the dielectric layer comprises magnesium fluoride.

5. The light-emitting diode of claim 1 wherein the dielectric layer has a thickness proportional to approximately a quarter-wavelength of the extracted light and inversely proportional to its refractive index.

6. The light-emitting diode of claim 1 wherein the plurality of electrically conductive contacts is a pattern of ohmic contacts covering less than half of the cross-sectional area of the dielectric layer.

7. The light-emitting diode of claim 6 wherein the pattern of ohmic contacts covers less than one-tenth of the cross-sectional area of the dielectric layer.

8. The light-emitting diode of claim 1 wherein the omni-directional reflector comprises an insulating layer having a refractive index of between about 1.10 and 2.25 underlying the top contact and a single conductive contact having a refractive index of between about 1.10 and 2.25 underlying an area beyond the periphery of the top contact.

9. The light-emitting diode of claim 8 wherein the insulating layer comprises silicon dioxide.

10. The light-emitting diode of claim 8 wherein the conductive contact comprises indium-tin-oxide.

11. The light-emitting diode of claim 1, wherein the plurality of electrically conductive contacts are electrically conductive metal contacts.

12. A light-emitting diode comprising:

an active region having two opposite conductivity-type confinement layers with a light-emitting region disposed between the layers;

an omni-directional reflector proximate a first one at the confinement layers opposite the light-emitting region; and

first and second windows, the first window being disposed adjacent the confinement layer and the second window being opposite the light-emitting region.

13. The light-emitting diode of claim 12 wherein the light-emitting region comprises a multiple quantum well structure, the confinement layers comprise AlGaInP doped with a p-type dopant and AlGaInP doped with a n-type dopant, and at least one of the windows comprise doped AlGaInP.

14. The light-emitting diode of claim 13 wherein one of the windows comprises essentially GaP.

15. The light-emitting diode of claim 14 wherein the first window comprises GaP.

16. The light-emitting diode of claim 14 wherein the second window comprises GaP.

17. The light-emitting diode of claim 13 wherein the first and second windows have a thickness of between about 1 and 25 microns.

18. The light-emitting diode of claim 13 wherein the first window has a thickness of between about 5 and 20 microns and the second window has a thickness of between about 1 and 15 microns.

19. The light-emitting diode of claim 12, wherein the omni-directional reflector includes one or more electrically conductive metal contacts.

20. A light-emitting diode comprising:

an active region having two opposite conductivity-type, confinement layers with a light-emitting region disposed between the layers; and

an omni-directional reflector proximate a first one or the confinement layers opposite the light-emitting region, wherein the omni-directional reflector comprises a dielectric layer having a low refractive index, an array of ohmic contacts extending through the dielectric layer, and a metal layer disposed proximate the dielectric layer opposite the light-emitting region.

21. The light-emitting diode of claim 20 wherein the array of ohmic contacts is disposed in a pattern underlying an area beyond the periphery of the top contact.