ELECTRICAL CURRENT DISTRIBUTION IN LIGHT EMITTING DEVICES

• US 20100117107A1
• Filed: 09/04/2007
• Published: 05/13/2010
• Est. Priority Date: 09/04/2006
• Status: Active Grant

• Current Assignee: Tinggi Technologies Pte., Ltd.
• Original Assignee: Tinggi Technologies Pte., Ltd.
• Inventors: Lin, Shi Ming, Yuan, Shu
• Granted Patent: US 8,124,994 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

A light emitting device is disclosed that has a plurality of epitaxial layers including an active layer, at least one of a reflective layer and an ohmic contact on a first side of the epitaxial layers; and a layer of a conductive metal on a second side of the epitaxial layers and having a light emitting surface. A terminal is on the light emitting surface, the terminal comprising an array for diffusing electrical current and minimizing its effect on light output. The array may have a bonding pad, an outer portion, and a joining portion connecting the bonding pad and the outer portion; the outer portion and the joining portion being for current dissipation.

Claims

1. A light emitting device comprising:

(a) a plurality of epitaxial layers including an active layer;

(b) at least one of a reflective layer and an ohmic contact on a first side of the epitaxial layers;

(c) a layer of a conductive metal on a second side of the epitaxial layers and having a light emitting surface; and

(d) a terminal on the light emitting surface, the terminal comprising an array for diffusing electrical current and minimizing its effect on light output.

2. A light emitting devices as claimed in claim 1, wherein the array comprises a bonding pad, an outer portion, and a joining portion connecting the bonding pad and the outer portion;

the outer portion and the joining portion being for current dissipation.

3. A light emitting device as claimed in claim 2, wherein the outer portion is at or adjacent a periphery of the light emitting surface.

4. A light emitting device as claimed in claim 2 or claim 3, wherein the joining portion comprises a plurality of spokes joining the bonding pad and the outer portion.

5. A light emitting device as claimed in any one of claims 1 to 4, wherein there is a second reflective layer between the array and the light emitting surface.

6. A light emitting device as claimed in any one of claims 2 to 4, wherein the second reflective layer is at a bottom of a trench in the light emitting surface.

7. A method of fabricating a light emitting device comprising a plurality of epitaxial layers including an active layer, a reflective layer on a first side of the epitaxial layers and a conductive metal on a second side of the epitaxial layer, the conductive metal having a light emitting surface;

the method comprising;

on the light emitting surface of the conductive metal, forming a terminal comprising an array for diffusing electrical current and minimizing its effect on light output.

8. A method as claimed in claim 7, wherein the forming of the array is by forming a bonding pad, an outer portion, and a joining portion electrically connecting the bonding pad and the outer portion;

the outer portion and the joining portion being for current dissipation.

9. A method as claimed in claim 8, wherein the outer portion is at or adjacent a periphery of the light emitting surface.

10. A method as claimed in claim 8 or claim 9, wherein the joining portion comprises a plurality of spokes joining the bonding pad and the outer portion.

11. A method as claimed in any one of claims 7 to 10 further comprising forming a second reflective layer on the light emitting surface before forming the array on the second reflective layer.

12. A method as claimed in any one of claims 8 to 10 further comprising forming a trench in the light emitting surface, forming a second reflective layer at a bottom of the trench, the array being formed on the second reflective layer.