LED for plant illumination
An epitaxial wafer for plant lighting light-emitting diodes (LED), the epitaxial wafer includes: a growth substrate; a first red-light epitaxial laminated layer; a distributed Bragg reflector (DBR) semiconductor laminated layer; and a second red-light epitaxial laminated layer; wherein: the first red-light epitaxial laminated layer comprises a first N-type ohmic contact layer, a first N-type covering layer, a first light-emitting layer, a first P-type covering layer, and a first P-type ohmic contact layer; and the second red-light epitaxial laminated layer comprises a second N-type ohmic contact layer, a second N-type covering layer, a second light-emitting layer, a second P-type covering layer, and a second P-type ohmic contact layer.
1. A light-emitting diode (LED) for plant lighting, comprising:
a first red-light epitaxial laminated layer having a first light-emitting layer; and a second red-light epitaxial laminated layer having a second light-emitting layer; wherein:
a light-emitting area of the first red-light epitaxial laminated layer is less than a light-emitting area of the second red-light epitaxial laminated layer; and
a light emitting wavelength of the first light-emitting layer is longer than a light emitting wavelength of the second light-emitting layer.
2. The LED of claim 1 , further comprising a distributed Bragg reflector (DBR) semiconductor laminated layer between the first red-light epitaxial laminated layer and the second red-light epitaxial laminated layer.
3. The LED of claim 2 , wherein the DBR semiconductor laminated layer is smaller than the light-emitting area of the second red-light epitaxial laminated layer, but larger than the light-emitting area of the first red-light epitaxial laminated layer.
4. The LED of claim 2 , wherein:
a surface of the second red-light epitaxial laminated layer is preset with a light-emitting area and a non-light-emitting area;
the DBR semiconductor laminated layer is formed on the non-light-emitting zone of the second red-light epitaxial laminated layer; and
the first red-light epitaxial laminated layer is formed on the DBR semiconductor laminated layer.
5. The LED of claim 4 , wherein a doping concentration of the DBR semiconductor laminated layer is 5×10 17 to thereby form a high-resistance interface.
6. The LED of claim 4 , wherein the DBR semiconductor laminated layer form a high-resistance interface, when injecting a current to the LED, the DBR semiconductor laminated layer prevents the current from entering into the non-light-emitting area of the second red-light epitaxial laminated layer, but flows as far as possible to the light-emitting area of the second red-light epitaxial laminated layer.
7. The LED of claim 6 , further comprising an electrical coupling structure which electrically connects to the first red-light epitaxial laminated layer and the second red-light epitaxial laminated layer.
8. The LED of claim 7 , wherein:
the first red-light epitaxial laminated layer further includes a first N-type semiconductor layer and a first P-type semiconductor layer;
the second red-light epitaxial laminated layer further includes a second N-type semiconductor layer and a second P-type semiconductor layer; and
the first P-type semiconductor layer electrically connects to the second N-type semiconductor layer via the electrical coupling structure.
9. The LED of claim 8 , further comprising an electrical current diffusion structure disposed over a non-light-emitting area of the second N-type semiconductor layer.
10. The LED of claim 1 , further comprising a high-resistance semiconductor layer between the first red-light epitaxial laminated layer and the second red-light epitaxial laminated layer, and wherein:
a surface of the second red-light epitaxial laminated layer is preset with a light-emitting area and a non-light-emitting area;
the high-resistance semiconductor layer is formed on the non-light-emitting zone of the second red-light epitaxial laminated layer; and
the first red-light epitaxial laminated layer is formed on the high-resistance semiconductor layer.
11. The LED of claim 10 , when injecting a current to the LED, the high-resistance semiconductor layer prevents the current from entering into the non-light-emitting area of the second red-light epitaxial laminated layer, but flows as far as possible to the light-emitting area of the second red-light epitaxial laminated layer.
12. The LED of claim 11 , further comprising an electrical coupling structure which electrically connects to the first red-light epitaxial laminated layer and the second red-light epitaxial laminated layer.
13. The LED of claim 12 , wherein:
the first red-light epitaxial laminated layer further includes a first N-type semiconductor layer and a first P-type semiconductor layer;
the second red-light epitaxial laminated layer further includes a second N-type semiconductor layer and a second P-type semiconductor layer; and
the first P-type semiconductor layer electrically connects to the second N-type semiconductor layer via the electrical coupling structure.
14. The LED of claim 13 , further comprising an electrical current diffusion structure disposed over a non-light-emitting area of the second N-type semiconductor layer.
15. The LED of claim 1 , wherein a light emitting wavelength of the first light-emitting layer is 710 nm-750 nm, and a light emitting wavelength of the second light-emitting layer is 640 nm-680 nm.
16. The LED of claim 15 , wherein the light emitting wavelength of the first light-emitting layer is 730 nm, and the light emitting wavelength of the second light-emitting layer is 660 nm.
17. The LED of claim 1 , wherein the light-emitting area of the first red-light epitaxial laminated layer is one-third of the light-emitting area of the second red-light epitaxial laminated layer.
18. A fabrication method of a plant lighting light-emitting diode (LED), the method comprising:
providing a LED epitaxial wafer, which comprising: a first red-light epitaxial laminated layer includes a first light-emitting layer, and a second red-light epitaxial laminated layer includes a second light-emitting layer, wherein a light emitting wavelength of the first light-emitting layer is longer than a light emitting wavelength of the second light-emitting layer;
defining a first light-emitting zone and a second light-emitting zone on the epitaxial wafer surface; and
removing the red-light epitaxial laminated layer of the second light-emitting area to forming a first light-emitting area for the first red-light epitaxial laminated layer and a second light-emitting area for the second red-light epitaxial laminated layer;
where the first light-emitting area is less than the second light-emitting area.
19. The method of claim 18 , wherein the epitaxial wafer further comprising a DBR semiconductor laminated layer between the first red-light epitaxial laminated layer and the second red-light epitaxial laminated layer, and also removing the DBR semiconductor laminated layer of the second light-emitting area.
20. The method of claim 19 , further comprising:
forming an electrical coupling structure which electrically connects to the first red-light epitaxial laminated layer and the second red-light epitaxial laminated layer.