Distributed current blocking structures for light emitting diodes

• US 9,070,833 B2
• Filed: 08/15/2013
• Issued: 06/30/2015
• Est. Priority Date: 08/04/2011
• Status: Active Grant

• Current Assignee: Alpad Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Chuang, Chih-Wei, Lin, Chao-Kun
• Primary Examiner(s): Fulk, Steven J
• Assistant Examiner(s): WARD, ERIC A
• Application Number:
  US13/967,982
• Publication Number:
  US 20140054640A1
• Time in Patent Office: 684 Days
• Field of Search: 257 79-103, 257E33001-E33077, 438 22- 47
• US Class Current: 1/1
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• 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 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/38 with a particular shape
• 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
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

An LED device includes a strip-shaped electrode, a strip-shaped current blocking structure and a plurality of distributed current blocking structures. The current blocking structures are formed of an insulating material such as silicon dioxide. The strip-shaped current blocking structure is located directly underneath the strip-shaped electrode. The plurality of current blocking structures may be disc shaped portions disposed in rows adjacent the strip-shaped current blocking structure. Distribution of the current blocking structures is such that current is prevented from concentrating in regions immediately adjacent the electrode, thereby facilitating uniform current flow into the active layer and facilitating uniform light generation in areas not underneath the electrode. In another aspect, current blocking structures are created by damaging regions of a p-GaN layer to form resistive regions. In yet another aspect, current blocking structures are created by etching away highly doped contact regions to form regions of resistive contact between conductive layers.

Claims

1. A light emitting device comprising:

a semiconductor layer;

a strip-shaped electrode formed on the semiconductor layer and including at least one closed opening having a rectangular shape in a plan view, wherein a current flowing through the strip-shaped electrode causes light to be emitted from the light emitting device;

a strip-shaped current blocking structure disposed directly underneath the strip-shaped electrode;

a first row of a plurality of current blocking structures formed along a periphery of the closed opening; and

a second row of a plurality of current blocking structures formed parallel to the first row such that the first row is disposed between the second row and the strip-shaped current blocking structure,

wherein a proportion of a region covered by the plurality of current blocking structures decreases in a direction away from the strip-shaped current blocking structure in the plan view, and

the plurality of current blocking structures are formed inside the closed opening in the plan view.

2. The light emitting device of claim 1, wherein the plurality of current blocking structures are formed along four sides of the rectangular shape of the closed opening in the plan view.

3. The light emitting device of claim 1, wherein a first distance between the strip-shaped current blocking structure and the first row is smaller than a second distance between the first row and the second row.

4. The light emitting device of claim 1, wherein the strip-shaped electrode includes a plurality of the closed openings, and the plurality of current blocking structures including the first row and the second row are formed inside each of the closed openings in the plan view.

5. The light emitting device of claim 1, wherein the closed opening is surrounded by the strip-shaped electrode in the plan view.

6. A light emitting device comprising:

a semiconductor layer;

a strip-shaped electrode formed on the semiconductor layer and including at least one closed opening having a rectangular shape in a plan view, wherein a current flowing through the strip-shaped electrode causes light to be emitted from the light emitting device;

a strip-shaped current blocking structure disposed directly underneath the strip-shaped electrode;

a first row of a plurality of current blocking structures formed along a periphery of the closed opening; and

a second row of a plurality of current blocking structures formed parallel to the first row such that the first row is disposed between the second row and the strip-shaped current blocking structure,

wherein a proportion of a region of the semiconductor layer through which the current flows increases in a direction away from the strip-shaped electrode in the plan view, and

the plurality of current blocking structures are formed inside the closed opening in the plan view.

7. The light emitting device of claim 6, wherein the plurality of current blocking structures are formed along four sides of the rectangular shape of the closed opening in the plan view.

8. The light emitting device of claim 6, wherein a first distance between the strip-shaped current blocking structure and the first row is smaller than a second distance between the first row and the second row.

9. The light emitting device of claim 6, wherein the strip-shaped electrode includes a plurality of the closed openings, and the plurality of current blocking structures including the first row and the second row are formed in each of the closed openings.

10. The light emitting device of claim 6, wherein the closed opening is surrounded by the strip-shaped electrode in the plan view.

11. A light emitting device comprising:

a semiconductor layer;

a rectangular strip-shaped electrode formed on the semiconductor layer and including at least one closed opening having a rectangular shape in a plan view, the rectangular strip-shaped electrode having a long side in a first direction and a short side in a second direction;

a strip-shaped current blocking structure disposed underneath the strip-shaped electrode; and

a plurality of current blocking structures disposed on a surface of the semiconductor layer along with the strip-shaped current blocking structure, wherein the proportion of the surface covered by the plurality of current blocking structures decreases in the second direction,

wherein the plurality of current blocking structures are formed inside the closed opening in the plan view.

12. The light emitting device of claim 11, wherein each of the plurality of current blocking structures has a disc shape.

13. The light emitting device of claim 11, wherein a current from the strip-shaped electrode flows between the current blocking structures such that the current flowing through the surface is substantially uniform in areas not underneath the strip-shaped electrode.

14. The light emitting device of claim 11, further comprising one or more intervening layers between the strip-shaped electrode and the strip-shaped current blocking structure.

15. The light emitting device of claim 11, wherein the plurality of current blocking structures are plasma damaged regions of the semiconductor layer.

16. The light emitting device of claim 11, wherein the plurality of current blocking structures are formed along four sides of the rectangular shape of the closed opening in the plan view.

17. The light emitting device of claim 11, wherein the closed opening is surrounded by the rectangular strip-shaped electrode in the plan view.