Strained AlGaInP layers for efficient electron and hole blocking in light emitting devices

• US 10,522,717 B2
• Filed: 09/25/2018
• Issued: 12/31/2019
• Est. Priority Date: 07/28/2017
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Inventors: Bhusal, Lekhnath, Chung, Theodore, Deb, Parijat
• Primary Examiner(s): Le, Thao P
• Application Number:
  US16/141,154
• Publication Number:
  US 20190035977A1
• Time in Patent Office: 462 Days
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/36 characterised by the electrodes

Abstract

A light-emitting device is disclosed. The light emitting device includes an electron blocking layer, a hole blocking layer, wherein at least a portion of the hole blocking layer is arranged to have a compressive strain, and an active layer disposed between the hole blocking layer and the electron blocking layer. The active layer may include a first barrier layer arranged to have a tensile strain, a second barrier layer arranged to have a tensile strain, and a first well layer disposed between the first barrier layer and the second barrier layer. The active layer may also include a first unstrained barrier layer, a second unstrained barrier layer, and a second well layer disposed between the first unstrained barrier layer and the second unstrained barrier layer.

Claims

1. A light-emitting device, comprising:

an electron blocking layer;

a hole blocking layer, at least a portion of the hole blocking layer having a compressive strain; and

an active layer disposed between the hole blocking layer and the electron blocking layer, the active layer including;

a first barrier layer having a first tensile strain,

a second barrier layer having a second tensile strain,

a first well layer disposed between the first barrier layer and the second barrier layer,

a first unstrained barrier layer,

a second unstrained barrier layer, and

a second well layer disposed between the first unstrained barrier layer and the second unstrained barrier layer.

2. The light-emitting device of claim 1, wherein the electron blocking layer has a composition represented as (Al_xGa_(1-x))_1-yIn_yP, where 0.4<

x<

1 and 0.2<

y<

0.7.

3. The light-emitting device of claim 1, wherein:

the electron blocking layer includes a first p-type layer and a second p-type layer,

the first p-type layer is unstrained, and

the second p-type layer has a third tensile strain.

4. The light-emitting device of claim 1, further comprising a GaAs substrate, wherein:

the hole blocking layer, the electron blocking layer, and the active layer are on the same side of the GaAs substrate, and

each of the hole blocking layer, the electron blocking layer, and the active layer is formed of a respective material from a system of AlGaInP.

12. The light-emitting device of claim 1, wherein the first tensile strain and the second tensile strain are the same.

5. A light-emitting device, comprising:

an electron blocking layer, at least a portion of the electron blocking layer having a first tensile strain;

a hole blocking layer, at least a portion of the hole blocking layer having a compressive strain; and

an active layer between the hole blocking layer and the electron blocking layer, the active layer including one or more of a first well structure and one or more of a second well structure, the first well structure including a first barrier layer that has a second tensile strain, a second barrier layer that has a third tensile strain, and a first well layer disposed between the first barrier layer and the second barrier layer, and the second well structure including a first unstrained barrier layer, a second unstrained barrier layer, and a second well layer disposed between the first unstrained barrier layer and the second unstrained barrier layer;

the electron blocking layer being part of one of an upper confinement layer of the light emitting device and a lower confinement layer of the light-emitting device, an the hole blocking layer being part of the other one of the upper confinement layer of the light emitting device and the lower confinement layer of the light-emitting device.

6. The light-emitting device of claim 5, wherein the hole blocking layer has a composition represented as (Al_xGa_(1-x))_1-yIn_yP, where 0.4<

x<

1 and 0.49<

y<

0.7.

7. The light-emitting device of claim 5, wherein:

the hole blocking layer includes a first n-type layer and a second n-type layer,

the first n-type layer is unstrained,

the second n-type layer is strained compressively,

the first n-type layer has a composition represented as (Al_xGa_(1-x))_1-yIn_yP, where 0≤

x≤

1 and 0.49≤

y≤

1.

8. The light-emitting device of claim 5, wherein the electron blocking layer has a composition represented as (Al_xGa_(1-x))_1-yIn_yP, where 0.4≤

x≤

1 and 0.2≤

y≤

0.7.

9. The light-emitting device of claim 5, wherein the electron blocking layer includes a first unstrained p-type layer and a second p-type layer that has a fourth tensile strain.

13. The light-emitting device of claim 5, wherein at least two of the first tensile strain, the second tensile strain, and the third tensile strain are the same.

10. A light-emitting device, comprising:

an electron blocking layer;

a hole blocking layer, the hole blocking layer including a first unstrained n-type layer and a second n-type layer that has a compressive strain; and

an active layer between the hole blocking layer and the electron blocking layer, the active layer including one or more of a first well structure and one or more of a second well structure,

the first well structure including a first barrier layer that has a first tensile strain, a second barrier layer that has a second tensile strain, and a well layer disposed between the first barrier layer and the second barrier layer, the first barrier layer and the second barrier layer having a composition represented as (Al_xGa_(1-x))_1-yIn_yP, where 0.4<

x<

1 and 0<

y<

0.49,

the second well structure including a first unstrained barrier layer, a second unstrained barrier layer, and a second well layer disposed between the first unstrained barrier layer and the second unstrained barrier layer; and

the first n-type layer being formed of a first material from a system of AlGaInP, the second n-type layer formed of a second material from the system of AlGaInP that has a greater indium-ratio than the first material.

11. The light-emitting device of claim 10, wherein the electron blocking layer includes a first unstrained p-type layer and a second p-type layer that has a third tensile strain.

14. The light-emitting device of claim 10, wherein the first tensile strain and the second tensile strain are the same.