Multi-junction light-emitting diode and method for making the same

Patent metadata

Field	Value
Publication number	US-12119425-B2
Application number	US-202217655097-A
Country	US
Kind code	B2
Filing date	Mar 16, 2022
Priority date	Feb 19, 2020
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

A multi-junction light-emitting diode (LED) includes a first epitaxial structure, a second epitaxial structure and a tunnel junction structure disposed therebetween. The tunnel junction structure includes a In z Al X1 Ga 1−X1 As highly doped p-type semiconductor layer wherein z ranges from 0 to 0.05, a Al X2 Ga 1−X2 As first composition graded layer wherein X2 is greater than 0 and less than X1, a Ga Y In 1−Y P highly doped n-type semiconductor layer and a Al X3 Ga 1−X3 As second composition graded layer that are sequentially disposed on the first epitaxial structure in such order. A method for making the abovementioned multi-junction LED is also disclosed.

First claim

What is claimed is:

1. A multi-junction light-emitting diode (LED), comprising a first epitaxial structure, a second epitaxial structure, and a tunnel junction structure disposed between said first epitaxial structure and said second epitaxial structure, said tunnel junction structure including:
a highly doped p-type semiconductor layer that is made of a material represented by In z Al X1 Ga 1−X1 As, z ranging from 0 to 0.05;
a first composition graded layer that is disposed on said highly doped p-type semiconductor layer and that is made of a material represented by Al X2 Ga 1−X2 As, X2 being greater than 0 and less than X1;
a highly doped n-type semiconductor layer that is disposed on said first composition graded layer opposite to said highly doped p-type semiconductor layer and that is made of a material represented by Ga Y In 1−Y P; and
a second composition graded layer that is disposed on said highly doped n-type semiconductor layer opposite to said first composition graded layer and that is made of a material represented by Al X3 Ga 1−X3 As.

2. The multi-junction LED of claim 1 , wherein in said highly doped p-type semiconductor layer, X1 is greater than 0 and not greater than 0.8.

3. The multi-junction LED of claim 1 , wherein said highly doped p-type semiconductor layer has a doping concentration not less than 1×10 19 cm −3 .

4. The multi-junction LED of claim 1 , wherein said highly doped p-type semiconductor layer is doped with carbon at a doping concentration ranging from 1×10 19 cm −3 to 2×10 20 cm −3 .

5. The multi-junction LED of claim 1 , wherein said highly doped p-type semiconductor layer has a thickness ranging from 10 nm to 100 nm.

6. The multi-junction LED of claim 1 , wherein in said highly doped n-type semiconductor layer, Y ranges from 0.45 to 0.7.

7. The multi-junction LED of claim 1 , wherein said highly doped n-type semiconductor layer has a doping concentration not less than 1×10 19 cm −3 .

8. The multi-junction LED of claim 1 , wherein said highly doped n-type semiconductor layer is doped with tellurium at a doping concentration ranging from 1×10 19 cm −3 to 2×10 20 cm −3 .

9. The multi-junction LED of claim 8 , wherein said highly doped n-type semiconductor layer is further doped with silicon at a doping concentration ranging from 5×10 18 cm −3 to 2×10 19 cm −3 .

10. The multi-junction LED of claim 9 , wherein in said highly doped n-type semiconductor layer, the doping concentration of tellurium to the doping concentration of silicon is in a ratio ranging from 5:3 to 2:1.

11. The multi-junction LED of claim 1 , wherein said highly doped n-type semiconductor layer has a thickness ranging from 10 nm to 100 nm.

12. The multi-junction LED of claim 1 , wherein in said first composition graded layer, X2 gradually decreases in a direction from said highly doped p-type semiconductor layer toward said highly doped n-type semiconductor layer.

13. The multi-junction LED of claim 12 , wherein X2 linearly decreases in a direction from said highly doped p-type semiconductor layer toward said highly doped n-type semiconductor layer.

14. The multi-junction LED of claim 1 , wherein said first composition graded layer is a p-type semiconductor layer which is doped with carbon at a doping concentration ranging from 1×10 19 cm −3 to 5×10 19 cm −3 .

15. The multi-junction LED of claim 1 , wherein said first composition graded layer has a thickness ranging from 10 nm to 50 nm.

16. The multi-junction LED of claim 1 , wherein in said second composition graded layer, X3 gradually increases in a direction away from said highly doped n-type semiconductor layer.

17. The multi-junction LED of claim 16 , wherein X3 linearly increases in a direction away from said highly doped n-type semiconductor layer.

18. The multi-junction LED of claim 1 , wherein said second composition graded layer is an n-type semiconductor layer which is doped with tellurium at a doping concentration ranging from 1×10 19 cm −3 to 5×10 19 cm −3 .

19. The multi-junction LED of claim 1 , wherein said second composition graded layer has a thickness ranging from 10 nm to 50 nm.

20. The multi-junction LED of claim 1 , wherein each of said first and second epitaxial structures independently emits an infrared light having a wavelength ranging from 760 nm to 1100 nm.

21. A method for making a multi-junction LED, comprising the steps of:
(A) forming a first epitaxial structure,
(B) forming a tunnel junction structure on the first epitaxial structure, wherein the tunnel junction structure includes:
a highly doped p-type semiconductor layer that is made of a material represented by In z Al X1 Ga 1−X1 As, z ranging from 0 to 0.05;
a first composition graded layer that is disposed on the highly doped p-type semiconductor layer and that is made of a material represented by Al X2 Ga 1−X2 As, X2 being greater than 0 and less than X1;
a highly doped n-type semiconductor layer that is disposed on the first composition graded layer opposite to the highly doped p-type semiconductor layer and that is made of a material represented by Ga Y In 1−Y P; and
a second composition graded layer that is disposed on the highly doped n-type semiconductor layer opposite to the first composition graded layer and that is made of a material represented by Al X3 Ga 1−X3 As, and

(C) forming a second epitaxial structure on the tunnel junction structure opposite to the first epitaxial structure.

Assignees

• Tianjin Sanan Optoelectronics Co Ltd

Inventors

• Hsiao Chihhung
• Peng Yu-Ren
• Cai Kunhuang
• Wang Duxiang
• Chang Chia-Hung

Classifications

• H10H20/018

  Bonding of wafers · CPC title

• H10H20/8215

  characterised by crystalline imperfections, e.g. dislocations; characterised by the distribution of dopants, e.g. delta-doping · CPC title

• H10H20/812 Primary

  within the light-emitting regions, e.g. having quantum confinement structures · CPC title

• H10H20/0137

  the light-emitting regions comprising nitride materials · CPC title

• H10H20/813 Primary

  having a plurality of light-emitting regions, e.g. multi-junction LEDs or light-emitting devices having photoluminescent regions within the bodies · CPC title