HIGH EFFICIENCY LIGHT EMITTING DIODE AND METHOD FOR FABRICATING THE SAME

• US 20110241045A1
• Filed: 02/01/2011
• Published: 10/06/2011
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Seoul Optodevice Company Limited (Seoul Semiconductor Co., Ltd.)
• Inventors: SHIN, Jin Cheol, LIM, Hong Chol, KIM, Chang Youn, LEE, Joon Hee, YOU, Jong Kyun, YE, Kyung Hee
• Granted Patent: US 8,772,805 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• 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 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A high-efficiency light emitting diode including: a semiconductor stack positioned on a support substrate, including a p-type compound semiconductor layer, an active layer, and an n-type compound semiconductor layer; an insulating layer disposed in an opening that divides the p-type compound semiconductor layer and active layer; a transparent electrode layer disposed on the insulating layer and the p-type compound semiconductor layer; a reflective insulating layer covering the transparent electrode layer, to reflect light from the active layer away from the support substrate; a p-electrode covering the reflective insulating layer; and an n-electrode is formed on top of the n-type compound semiconductor layer. The p-electrode is electrically connected to the transparent electrode layer through the insulating layer.

Claims

1. A light emitting diode (LED) comprising:

a support substrate;

a semiconductor stack disposed on the support substrate, the semiconductor stack comprising a p-type compound semiconductor layer, an active layer, and an n-type compound semiconductor layer, the p-type compound semiconductor layer being disposed closer to the support substrate than the n-type compound semiconductor layer, the semiconductor stack having an opening that divides the p-type compound semiconductor layer and active layer and exposes a portion of the n-type compound semiconductor layer;

an insulating layer disposed on the exposed portion of the n-type compound semiconductor layer and a sidewall of the opening;

a transparent electrode layer disposed in ohmic-contact with the p-type compound semiconductor layer and covering the insulating layer and the p-type compound semiconductor layer;

a reflective insulating layer covering the transparent electrode layer, to reflect light is emitted from the active layer away from the support substrate;

a p-electrode covering the reflective insulating layer; and

an n-electrode disposed on the upper surface of the n-type compound semiconductor layer,

wherein the p-electrode is electrically connected to the transparent electrode layer through an opening formed in the reflective insulating layer.

2. The LED as claimed in claim 1, further comprising a p-electrode pad disposed on a portion of the p-electrode that extends outside of the semiconductor stack.

3. The LED as claimed in claim 1, wherein the reflective insulating layer is a distributed Bragg reflector (DBR).

4. The LED as claimed in claim 1, wherein the reflective insulating layer is formed by alternately stacking at least two layers selected from the group consisting of Si_xO_yN_z, Ti_xO_y, Ta_xO_y, and Nb_xO_y layers.

5. The LED as claimed in claim 1, wherein the reflective insulating layer comprises at least one element selected from the group consisting of Si, Ti, Ta, Nb, In, and Sn.

6. The LED as claimed in claim 1, further comprising a bonding metal disposed between the p-electrode and the support substrate.

7. The LED as claimed in claim 1, wherein the transparent electrode layer comprises a metal or a conductive metal oxide.

8. The LED as claimed in claim 1, wherein the reflective insulating layer has a plurality of openings that are filled with portions of the p-electrode.

9. The LED as claimed in claim 1, wherein the width of the opening decreases as it approaches the n-type compound semiconductor layer.

10. The LED as claimed in claim 1, wherein:

first protrusions are formed on the upper surface of the n-type compound semiconductor layer; and

a dielectric material is disposed on the upper surface, so as to cover the first protrusions.

11. The LED as claimed in claim 10, wherein the upper surface of the dielectric material has second protrusions.

12. The LED as claimed in claim 11, wherein:

the first protrusions are generally pyramidal, and the second protrusions are generally conical.

13. The LED as claimed in claim 11, wherein at least one of the second protrusions covers at least two of the first protrusions.

14. The LED as claimed in claim 10, wherein the upper surface of the n-type compound semiconductor layer has a higher surface roughness than the upper surface of the dielectric material.

15. The LED as claimed in claim 10, wherein the first protrusions are formed by photo electro chemical etching.

16. A method of fabricating a light emitting diode (LED), comprising:

growing an n-type compound semiconductor layer, an active layer, and a p-type compound semiconductor layer on a growth substrate;

forming an opening in the p-type compound semiconductor layer and the active layer to expose a portion of the n-type compound semiconductor layer;

forming an insulating layer on the exposed portion of the n-type compound semiconductor layer and on a sidewall of the opening;

forming a transparent electrode layer on the insulating layer and the p-type compound semiconductor layer;

forming a reflective insulating layer on the transparent electrode layer;

removing a portion of the reflective insulating layer to expose a portion of the transparent electrode layer;

forming a p-electrode on the reflective insulating layer;

bonding a support substrate to the p-electrode using a bonding metal; and

removing the growth substrate,

wherein the p-electrode is electrically connected to the exposed portion of the transparent electrode layer.

17. The method as claimed in claim 16, wherein the reflective insulating layer is a distributed Bragg reflector (DBR).

18. A light emitting diode (LED) comprising:

a support substrate;

a semiconductor stack disposed on the support substrate and having an upper surface that faces away from the substrate, the semiconductor stack comprising a p-type compound semiconductor layer, active layer, and an n-type compound semiconductor layer;

a first electrode disposed between the support substrate and the semiconductor stack, in ohmic-contact with the semiconductor stack, and extending outside of the semiconductor stack;

a first bonding pad disposed on the portion of the first electrode that is disposed outside of the semiconductor stack, the first bonding pad being electrically connected to the first electrode; and

a second electrode positioned on the upper surface of the semiconductor stack,

wherein first protrusions are formed on the upper surface of the semiconductor stack, and a dielectric material is disposed on the upper surface, covering the first protrusions.

19. The LED as claimed in claim 18, wherein the upper surface of the semiconductor stack a higher surface roughness than the upper surface of the dielectric material.

20. The LED as claimed in claim 19, wherein the dielectric material has second protrusions formed on the upper surface thereof.

21. The LED as claimed in claim 18, wherein some of the second protrusions cover more than one of the first protrusions.

22. The LED as claimed in claim 18, wherein the first protrusions are generally pyramidal and the second protrusions are generally conical.

23. The LED as claimed in claim 18, wherein the first protrusions are formed by photo-electro chemical etching.

24. The LED as claimed in claim 18, wherein the support substrate is a sapphire substrate.

25. The LED as claimed in claim 18, wherein the first electrode comprises a reflection layer and a protection layer to protect the reflection layer.

26. The LED as claimed in claim 25, wherein the reflection layer is embedded in the protection layer, between the protection layer and the semiconductor stack.

27. The LED as claimed in claim 18, wherein the first electrode is in ohmic-contact with the p-type compound semiconductor layer.