LED for plant illumination
A light-emitting diode (LED) for plant illumination includes a substrate, and a PN-junction light-emitting portion over the substrate. The light-emitting portion has a strained light-emitting layer with a component formula of Ga X In (1-X) As Y P (1-Y) (0<X<1 and 0<Y<1), and a barrier layer, forming a 2˜40-pair alternating-layer structure with the strained light-emitting layer.
1. An epitaxial wafer for a plant lighting light-emitting diode (LED), comprising:
a PN junction light-emitting portion; and
a window layer substantially transparent to light emitted from the light-emitting portion and also configured to have a current spreading function;
wherein:
the PN junction light-emitting portion comprises a strained light-emitting layer with a component formula of Ga X In (1-x) As Y P (1-Y) , 0<X<1 and 0<Y≤0.05 such that the light is suitable for plant illumination;
the PN junction light-emitting portion comprises:
a first red-light epitaxial laminated layer;
a 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.
2. The epitaxial wafer of claim 1 , wherein a doping concentration of the DBR semiconductor laminated layer is ≤5×10 17 to thereby form a high resistance interface.
3. The epitaxial wafer 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.
4. The epitaxial wafer of claim 3 , 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.
5. The epitaxial wafer of claim 1 , further comprising an etching stop layer between the DBR semiconductor laminated layer and the second red-light epitaxial laminated layer.
6. A light-emitting system for plant lighting, comprising a plurality of light-emitting diode (LED) chips, each chip comprising:
a PN junction light-emitting portion; and
a window layer substantially transparent to light emitted from the light-emitting portion and also configured to have a current spreading function;
wherein:
the PN junction light-emitting portion comprises a strained light-emitting layer with a component formula of Ga X In (1-X) As Y P (1-Y) , 0<X<1 and 0<Y≤0.05 such that the light is suitable for plant illumination;
the PN junction light-emitting portion comprises:
a first red-light epitaxial laminated layer;
a DBR semiconductor laminated layer;
a second red-light epitaxial laminated layer; and
a conductive bonding substrate;
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;
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;
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;
the first N-type ohmic contact layer is provided with a first electrode;
between the first P-type ohmic contact layer and the second N-type ohmic contact layer is provided with an electronic-connected structure; and
the second P-type ohmic contact layer is provided with a second electrode.
7. The system of claim 6 , wherein:
a doping concentration of the DBR semiconductor laminated layer is ≤5×10 17 to thereby form a high resistance interface;
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;
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 area of the second red-light epitaxial laminated layer;
an area of the DBR semiconductor laminated layer is less 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; and
the non-light-emitting area of the second N-type ohmic contact layer is provided with an electric diffusion structure.