LIGHT-EMITTING DIODE

• US 20170005227A1
• Filed: 09/15/2016
• Published: 01/05/2017
• Est. Priority Date: 02/18/2015
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Peng, Yu-Ren, Hsu, Tzu-Chieh, Chen, Shih-I, Lee, Rong-Ren, Chung, Hsin-Chan, Liao, Wen-Luh, Lin, Yi-Chieh
• Granted Patent: US 10,367,118 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A light-emitting diode, comprises an active layer for emitting a light ray; an upper semiconductor stack on the active layer, wherein the upper semiconductor stack comprises a window layer; a reflector; and a lower semiconductor stack between the active layer and the reflector; wherein the thickness of the window layer is small than or equal to 3 μm, and the thickness of the lower semiconductor stack is small than or equal to 1 μm.

Claims

1. A light-emitting diode, comprising:

an active layer for emitting a light ray;

an upper semiconductor stack on the active layer, wherein the upper semiconductor stack comprises a window layer;

a reflector; and

a lower semiconductor stack between the active layer and the reflector;

wherein the thickness of the window layer is small than or equal to 3 μ

m, and the thickness of the lower semiconductor stack is small than or equal to 1 μ

m.

2. The light-emitting diode according to claim 1, wherein the lower semiconductor stack comprises multiple semiconductor layers, the light ray with a phase and a peak wavelength λ

in air, and each of the multiple semiconductor layers has a refractive index ni, a thickness di, for one of the multiple semiconductor layers traveled through by the light ray, the thickness di satisfies the following conditions of;

0.8*((2m−

1)/4)*(λ

/ni)≦

di≦

1.2*((2m−

1)/4)*(λ

/ni),

where m is a natural number.

3. The light-emitting diode according to claim 2, wherein the thickness di of the one of the multiple semiconductor layers is larger than one seventh of the peak wavelength λ

in air.

4. The light-emitting diode according to claim 1, wherein the lower semiconductor stack comprises p-type semiconductor material and the upper semiconductor stack comprise n-type semiconductor material.

5. The light-emitting diode according to claim 2, wherein the multiple semiconductor layers comprise a confining layer on the active layer, a cladding layer on the confining layer, a buffer layer on the cladding layer, and a contact layer on the cladding layer.

6. The light-emitting diode according to claim 5, wherein the contact layer comprises GaP.

7. The light-emitting diode according to claim 5, wherein the thickness of the contact layer is smaller than one seventh of the peak wavelength λ

in air.

8. The light-emitting diode according to claim 5, wherein the confining layer contacting two adjacent layers, and the confining layer has a refractive index between the refractive indices of the two adjacent layers.

9. The light-emitting diode according to claim 5, wherein the cladding layer contacting two adjacent layers, and the cladding layer has a refractive index smaller than the refractive indices of the two adjacent layers.

10. The light-emitting diode according to claim 5, wherein the contact layer contacting two adjacent layers, and the contact layer has a refractive index larger than the refractive indices of the two adjacent layers.

11. The light-emitting diode according to claim 2, wherein each of the multiple semiconductor layers has a refractive index between 2.8 and 3.6.

12. The light-emitting diode according to claim 2, wherein the peak wavelength λ

in air is larger than 550 nm.

13. The light-emitting diode according to claim 1, wherein the reflector comprises a metal layer contacting the lower semiconductor layer.

14. The light-emitting diode according to claim 1, wherein the reflector comprises a dielectric layer contacting the lower semiconductor layer and the refractive index of the dielectric layer is lower than or equal to 1.5.

15. The light-emitting diode according to claim 14, wherein the dielectric layer comprises SiNx, SiO₂, MgF₂, or combination thereof.

16. The light-emitting diode according to claim 1, wherein the reflector comprises a transparent conductive layer contacting the lower semiconductor layer and the refractive index of the transparent conductive layer is smaller than that of the lower semiconductor stack.

17. The light-emitting diode according to claim 16, wherein the transparent conductive layer comprises ITO, ATO, AZO, ZTO or ZnO.

18. The light-emitting diode according to claim 1, wherein a distance between the reflector and the active layer is between 200 nm and 1 μ

m.

19. The light-emitting diode according to claim 1, further comprising a substrate and bonding layer adhering the substrate and the reflector.

20. The light-emitting diode according to claim 19, further comprising a front electrode on the upper semiconductor stack, and a rear electrode on the substrate opposite to the reflector.