High efficiency light emitting diode and method of fabricating the same

Patent metadata

Field	Value
Publication number	US-9362449-B2
Application number	US-201414464179-A
Country	US
Kind code	B2
Filing date	Aug 20, 2014
Priority date	Feb 20, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

Disclosed herein are a high efficiency light emitting diode and a method of fabricating the same. The light emitting diode includes a semiconductor stacked structure disposed on the support substrate and including a gallium nitride-based p-type semiconductor layer, a gallium nitride-based active layer, and a gallium nitride-based n-type semiconductor layer; and a reflecting layer disposed between the support substrate and the semiconductor stacked structure, wherein the semiconductor stacked structure includes a plurality of protrusions having a truncated cone shape and fine cones formed on top surfaces of the protrusions. By this configuration, light extraction efficiency of the semiconductor stacked structure having low dislocation density can be improved.

First claim

The invention claimed is:

1. A light emitting diode, comprising:
a support substrate;
a semiconductor stacked structure disposed on the support substrate, comprising:
a gallium nitride-based p-type semiconductor layer having a dislocation density of 5×10 6 /cm 2 or less,
a gallium nitride-based active layer having a dislocation density of 5×10 6 /cm 2 or less, and
a gallium nitride-based n-type semiconductor layer having a dislocation density of 5×10 6 /cm 2 or less; and
a reflecting layer disposed between the support substrate ark :he semiconductor stacked structure,
wherein
the semiconductor stacked structure comprises a plurality of protrusions having a truncated cone shape and fine cones formed on top surfaces of the protrusions, and
a droop of the light emitting diode is less than 20% at 350 mA.

2. The light emitting diode of claim 1 , wherein each of the gallium nitride-based p-type semiconductor layer, the gallium nitride-based active layer and the gallium nitride-based n-type semiconductor layer is grown on a gallium nitride substrate.

3. The light emitting diode of claim 1 , wherein the protrusions are arranged in a honeycomb shape.

4. The light emitting diode of claim 1 , wherein the protrusions having the truncated cone shape are adjacent to each other and thus, a V-shaped groove of which the bottom is sharp is formed in a region therebetween.

5. The light emitting diode of claim 4 , wherein the bottom surfaces of the protrusions have a hexagonal shape.

6. The light emitting diode of claim 1 , wherein an average height of the protrusions exceeds 3 μm and an average height of the fine cones is 1 μm or less.

7. The light emitting diode of claim 1 , wherein the fine cones are disposed only on the top surfaces of the protrusions.

8. A method of fabricating the light emitting diode of claim 1 , comprising;
forming a semiconductor stacked structure by growing semiconductor layers including a gallium nitride-based n-type semiconductor layer, a gallium nitride-based active layer, and a gallium nitride-based p-type semiconductor layer on a gallium nitride substrate;
forming a support substrate on the semiconductor stacked structure; and
removing the gallium nitride substrate.

9. The method of claim 8 , further comprising: forming a plurality of protrusions having fine cones by etching a surface of the semiconductor stacked structure that is exposed by removing the gallium nitride substrate, wherein the plurality of protrusions have a truncated cone shape.

10. The method of claim 9 , wherein the forming of plurality of protrusions having the fine cones includes:
forming a mask pattern on the surface of the semiconductor stacked structure and performing dry etching on the semiconductor stacked structure by using the mask pattern as an etch ask to form the plurality of protrusions;
removing the mask pattern; and
forming fine cones by performing wet etching on the top surfaces of the plurality of protrusions.

11. The method of claim 10 , wherein the wet etching is performed using a boiling solution of KOH or NaOH.

12. The method of claim 10 , wherein a V-shaped groove of which the bottom is sharp is formed in a region between the protrusions so that the plurality of protrusions are adjacent to each other.

13. The method of claim 8 , wherein the removing of the gallium nitride substrate includes:
removing a portion of the gallium nitride substrate by grinding the gallium nitride substrate; and
removing a portion of the gallium nitride substrate remaining on the semiconductor stacked structure by an inductively coupled plasma reactive ion etching technology.

14. The method of claim 13 , further comprising: polishing the gallium nitride substrate after grinding the gallium nitride substrate.

15. The method of claim 13 , further comprising: performing a test to confirm whether the surface of the semiconductor stacked structure is exposed.

16. The method of claim 15 , wherein the test is performed by measuring surface resistance of the surface of the semiconductor stacked structure.

17. A light emitting diode, comprising:
a support substrate;
a semiconductor stacked structure disposed on the support substrate' comprising:
a gallium nitride-based p-type semiconductor layer having a dislocation density of from 1×10 4 /cm 2 to 5×10 6 /cm 2 ,
a gallium nitride-based active layer having a dislocation density of from 1×10 4 /cm 2 to 5×10 6 /cm 2 , and
a gallium nitride-based n-type semiconductor layer having a dislocation density of from 1×10 4 /cm 2 to 5×10 6 /cm 2 ; and
a reflecting layer disposed between the support substrate and the semiconductor stacked structure, wherein
the semiconductor stacked structure comprises a plurality of protrusions and fine cones formed on top surfaces of the protrusions, and
a droop of the light emitting diode is less than 20% at 350 mA.

18. A light emitting diode, comprising:
a support substrate;
a semiconductor stacked structure disposed on the support substrate, comprising: a gallium nitride-based p-type semiconductor layer having a dislocation density of from 1×10 4 /cm 2 to 5×10 6 /cm 2 ,
a gallium nitride-based active layer having a dislocation density of from 1×10 4 /cm 2 to 5×10 6 /cm 2 , and
a gallium nitride-based n-type semiconductor layer having a dislocation density of from 1×10 4 /cm 2 to 5×10 6 /cm 2 ; and
a reflecting layer disposed between the support substrate and the semiconductor stacked structure,
wherein the semiconductor stacked structure includes a plurality of recesses spaced apart from one another and fine cones formed on surfaces of a protruding portion between the recesses, and
a droop of the light emitting diode is less than 20% at 350 mA.

Assignees

• Seoul Viosys Co Ltd

Inventors

• Kim Chang Yeon
• Cho Dae Sung
• Nam Ki Bum
• Kim Young Wug
• You Jong Kyun
• Shimoyama Kenji
• Joichi Takahide
• Kurihara Kaori

Classifications

• H10H20/8316

  Multi-layer electrodes comprising at least one discontinuous layer · CPC title

• H10H20/0137

  the light-emitting regions comprising nitride materials · CPC title

• H10H20/84

  Coatings, e.g. passivation layers or antireflective coatings · CPC title

• H10H20/82

  Roughened surfaces, e.g. at the interface between epitaxial layers · CPC title

• H10H20/018

  Bonding of wafers · CPC title