LED structure and fabrication method
A light-emitting diode (LED) structure includes a substrate; a first semiconductor layer on the substrate; a light emitting layer on the first semiconductor layer; a second semiconductor layer on the light emitting layer; and an electrode on the semiconductor layer composed of a body and an extension body, wherein, the electrode extension portion is in a certain angle with the contacting semiconductor layer and separates the electrode body from the light emitted to its top surface and sides with a semi-wrapping structure.
1. A light-emitting diode (LED) structure, comprising: a substrate; a first semiconductor layer over the substrate; a light emitting layer over the first semiconductor layer; a second semiconductor layer over the light emitting layer; and an electrode over the second semiconductor layer and comprising a body and an extension portion separated from the body and are in contact with the second semiconductor layer, wherein the electrode extension portion with a semi-wrapping structure is in a specified angle with the second semiconductor layer and configured to reflect light that is directed toward a top surface and sides of the electrode body, away from the electrode body to thereby reduce light absorption by the electrode body.
2. The LED structure of claim 1 , wherein: the electrode body is a multi-layer structure; a bottom layer of the electrode body comprises a reflective metal configured to reflect light that is directed toward a bottom surface of the electrode body, away from the bottom surface; and a top layer of the electrode body comprises an anti-electromigration metal configured to prevent the reflective metal from electromigration during a conductive process.
3. The LED structure of claim 1 , wherein in the electrode extension portion, a surface proximal to the electrode body comprises an anti-electromigration metal, and an outer side surface distal from the electrode body comprises a reflective metal configured to reflect light that is directed toward the top surface and sides of the electrode body.
4. The LED structure of claim 1 , wherein the electrode extension portion is not lower than the electrode body.
5. The LED structure of claim 1 , wherein the electrode extension portion is in a straight, obtuse, or acute angle, or any combination thereof, with the second semiconductor layer which the electrode extension portion is in contact with.
6. The LED structure of claim 1 , wherein the electrode extension portion has a surface that is a regular plane, an irregular plane, or a combination thereof.
7. The LED structure of claim 1 , further comprising light conversion materials outside the electrode.
8. A fabrication method for a light-emitting diode (LED) structure, the method comprising: a) providing an LED wafer comprising a substrate for supporting and protecting the LED structure, a first semiconductor layer over the substrate, a light emitting layer over the first semiconductor layer, and a second semiconductor layer over the first semiconductor layer; b) dividing an upper surface of the second semiconductor layer into an electrode region and a non-electrode region, and forming a shield layer in the non-electrode region; c) depositing an electrode layer over the LED wafer in a specified angle θ with a surface of the LED wafer to plate the electrode layer at a side wall of the shield layer adjacent to the electrode region; and d) removing the shield layer and a portion of the electrode layer over the shield layer, and leaving the electrode layer in the electrode region and at the side wall of the shield layer, wherein the electrode layer at the electrode region is the electrode body, and the electrode layer at the side wall of the shield layer is the electrode extension portion; wherein the fabricated LED structure comprises: the substrate; the first semiconductor layer over the substrate; the light emitting layer over the first semiconductor layer; the second semiconductor layer over the light emitting layer; and the electrode over the second semiconductor layer and comprising a body and the extension portion separated from the body and are in contact with the second semiconductor layer, wherein the electrode extension portion with a semi-wrapping structure is in the specified angle θ with the second semiconductor layer and configured to reflect light that is directed toward a top surface and sides of the electrode body, away from the electrode body to thereby reduce light absorption by the electrode body.
9. The fabrication method of claim 8 , wherein 0°<θ<90°.
10. The fabrication method of claim 8 , wherein 30°≤θ≤80°.
11. The fabrication method of claim 8 , wherein the deposited electrode layer is a multi-layer structure with a first-deposited layer made of a reflective metal.
12. The fabrication method of claim 8 , wherein the deposited electrode layer is a multi-layer structure with a last-deposited layer made of an anti-electromigration metal.
13. The fabrication method of claim 8 , wherein after fabrication of the electrode, a light conversion material is deposited in areas outside the electrode.
14. A fabrication method for a light-emitting diode (LED) structure, the method comprising: a) providing an LED wafer, which comprises a substrate for supporting and protecting the LED, a first semiconductor layer on the substrate, a light emitting layer on the first semiconductor layer and a second semiconductor layer on the first semiconductor layer; b) dividing the upper surface of the second semiconductor layer into an electrode region and a non-electrode region, and forming a light conversion layer in the non-electrode region; c) depositing a shield layer on the light conversion layer and exposing the electrode region; d) depositing an electrode layer on the LED wafer in a specified angle θ with the LED wafer surface to plate the electrode layer at the side wall of the light conversion layer next to the electrode region; e) removing the shield layer and a portion of the electrode layer over the shield layer and leaving the electrode layer in the electrode region and at the side wall of the light conversion layer, wherein, the electrode layer in the electrode region is the electrode body and that at the side wall of the light conversion layer is the electrode extension portion; wherein the fabricated LED structure comprises: the substrate; the first semiconductor layer over the substrate; the light emitting layer over the first semiconductor layer; the second semiconductor layer over the light emitting layer; and the electrode over the second semiconductor layer and comprising a body and the extension portion separated from the body and are in contact with the second semiconductor layer, wherein the electrode extension portion with a semi-wrapping structure is in the specified angle θ with the second semiconductor layer and configured to reflect light that is directed toward a top surface and sides of the electrode body, away from the electrode body to thereby reduce light absorption by the electrode body.
15. The fabrication method of claim 14 , wherein 0°<θ<90°.
16. The fabrication method of claim 14 , wherein 30°≤θ≤80°.
17. The fabrication method of claim 14 , wherein the deposited electrode layer is a multi-layer structure with a first-deposited metal layer made of a reflective metal.
18. The fabrication method of claim 14 , wherein the deposited electrode layer is a multi-layer structure with a last-deposited layer made of an anti-electromigration metal.
19. The fabrication method of claim 14 , wherein the electrode extension portion is not lower than the electrode body.
20. The fabrication method of claim 14 , wherein the electrode extension portion is in an acute angle with the second semiconductor layer which the electrode extension portion is in contact with.