# US 8,541,789 B2 · Light-emitting device with patterned current diffusion layer

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- Number: US 8,541,789 B2
- Document ID: US8541789B2
- Status: Granted
- Kind: B2
- Application number: 12/949,863
- Filed: 2010-11-19
- Published: 2011-05-26
- Granted: 2013-09-24
- Earliest claimed: 2009-11-20
- Assignees: Epistar Corporation
- Applicants: Chiu Lin Yao; Ya Ian Yang
- Inventors: Chiu Lin Yao; Ya Ian Yang
- Web page: https://patentgrep.com/patent/US8541789B2

## CPC

- H10H 20/819: characterised by their shape, e.g. curved or truncated substrates
- H10H 20/018: {Bonding of wafers}
- H10H 20/82: Roughened surfaces, e.g. at the interface between epitaxial layers
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

Disclosed is a light-emitting device including a permanent substrate, an adhesive layer on the permanent substrate, a current diffusion layer on the adhesive layer, and a semiconductor stack layer on the current diffusion layer. The current diffusion layer has an etched portion and an unetched portion, wherein the etched and unetched portions have a horizontal height difference. The horizontal height difference and the current diffusion layer thickness have a ratio of 20:100 to 70:100.

## Claims

### Claim 1

A light-emitting device, comprising:
a permanent substrate;
an adhesive layer on the permanent substrate;
a current diffusion layer on the adhesive layer, wherein the current diffusion layer has an etched portion and an unetched portion;
a semiconductor stack layer on the current diffusion layer, comprising:
a second type semiconductor layer on the current diffusion layer;
an active layer on the second type semiconductor layer; and
a first type semiconductor layer on the active layer, wherein the first type semiconductor layer and the second type semiconductor layer have different electrical properties; and
a middle layer between the current diffusion layer and the semiconductor stack layer, wherein the difference between a thickness of the etched portion and a thickness of the unetched portion is about 20% to 70% of the thickness of the unetched portion of the current diffusion layer.

### Claim 2 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the permanent substrate is a transparent insulation substrate.

### Claim 3 (depends on 2)

The light-emitting layer as claimed in claim 2, wherein the adhesive layer is a transparent adhesive layer.

### Claim 4 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the permanent substrate is an opaque insulation substrate.

### Claim 5 (depends on 4)

The light-emitting layer as claimed in claim 4, wherein the adhesive layer is a metal adhesive layer.

### Claim 6 (depends on 4)

The light-emitting layer as claimed in claim 4, further comprising a reflection layer between the permanent substrate and the adhesive layer.

### Claim 7 (depends on 1)

The light-emitting layer as claimed in claim 1, wherein the current diffusion layer has a doping concentration greater than or equal to 5×1017/cm3.

### Claim 8 (depends on 1)

The light-emitting layer as claimed in claim 1, wherein the current diffusion layer is doped by Mg or Zn.

### Claim 9 (depends on 1)

The light-emitting device as claimed in claim 1, wherein a ratio of the doping concentration of the middle layer to the doping concentration of the current diffusion layer is less than or equal to 1:3.

### Claim 10 (depends on 1)

The light-emitting layer as claimed in claim 1, wherein the middle layer is doped by Mg or Zn.

### Claim 11 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the band gap of the current diffusion layer is greater than the band gap of any layer in the semiconductor stack layer.

### Claim 12 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the current diffusion layer comprises GaP or ZnO.

### Claim 13 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the middle layer comprises GaP or ZnO.

### Claim 14 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the current diffusion layer has a thickness greater than or equal to 4 μm.

### Claim 15 (depends on 1)

The light-emitting device as claimed in claim 1, wherein the current diffusion layer has a rough top surface and/or a rough bottom surface.

### Claim 16 (depends on 5)

The light-emitting device as claimed in claim 5, wherein the metal adhesive layer is selected form the group consisting of Au, Au—Sn, Sn, In, Au—Ag, and Pb—Sn.