Light emitting diodes with smooth surface for reflective electrode
View Patent ↗A light emitting diode comprising an epitaxial layer structure, a first electrode, and a second electrode. The first and second electrodes are separately disposed on the epitaxial layer structure, and the epitaxial layer structure has a root-means-square (RMS) roughness less than about 3 at a surface whereon the first electrode is formed.
1. A method for manufacturing a light emitting diode, comprising:
forming an epitaxial layer structure comprising a first epitaxial layer and a second epitaxial layer;
depositing a first electrode and a second electrode on the epitaxial layer structure; and
depositing a transparent ohmic contact layer between the second epitaxial layer and the second electrode,
wherein the first epitaxial layer is between the first electrode and the second epitaxial layer, and the second epitaxial layer is between the second electrode and the first epitaxial layer, and
the epitaxial layer structure has a root-means-square (RMS) roughness less than about 3 nm at a surface where the second electrode is formed.
2. The method of claim 1 , wherein the second electrode is formed by depositing metals including at least one selected from a group consisting of Ag, Pt, Ni, Cr, Ti, Al, Pd, W, Ru, Rh, Mo, and their alloys.
3. The method of claim 1 , wherein the second electrode is formed on the second epitaxial layer and a surface of the second epitaxial layer where the second electrode is formed has a root-means-square (RMS) roughness less than about 3 nm.
4. The method of claim 1 , wherein the first epitaxial layer is an n-type epitaxial layer and the second epitaxial layer is a p-type epitaxial layer.
5. The method of claim 4 , further comprises forming an active layer between the n-type epitaxial layer and the p-type epitaxial layer.
6. The method of claim 1 , wherein the first electrode is an n-type electrode and the second electrode is a p-type electrode.
7. The method of claim 1 , wherein the first epitaxial layer is laterally between the first electrode and the second epitaxial layer.
8. The method of claim 1 , wherein a surface of the transparent ohmic contact layer adjacent to the second electrode has a root-means-square (RMS) roughness less than about 3 nm.
9. The method of claim 1 , wherein the second epitaxial layer is formed via a MOCVD (Metal-Organic Chemical Vapor Deposition) using a metal-organic compound solution.
10. The method of claim 9 , wherein the second epitaxial layer is formed at a temperature no less than 950° C. at a growth rate no more than 150 Å/mim.
11. The method of claim 1 , wherein the first and second electrodes are deposited on either side of the epitaxial layer structure.
12. The method of claim 1 , wherein the light emitting diode is a vertical light emitting diode device.
13. The method of claim 1 , wherein the second electrode is mounted on a substrate.
14. The method of claim 13 , wherein the substrate is formed from a material selected from a group consisting of a metal, a semiconductor material, and a ceramic.
15. The method of claim 14 , wherein the metal includes at least one selected from a group consisting of Cu, Mo, W, and Al, wherein the semiconductor material includes at least one selected from a group consisting of Si, GaAs, GaP, InP, and Ge, and wherein the ceramic includes at least one selected from a group consisting of Al 2 O 3 and AlN.
16. The method of claim 1 , wherein the first and second electrodes are deposited on one side of the epitaxial layer structure.
17. The method of claim 16 , wherein the light emitting diode is a flip-chipped lateral light emitting diode device.
18. The method of claim 1 , wherein the epitaxial layer structure includes a p-type epitaxial layer and a n-type epitaxial layer, and the p-type epitaxial layer is laterally between the second electrode and the n-type epitaxial layer.
19. The method of claim 1 , wherein the second epitaxial layer is laterally between the second electrode and the n-type epitaxial layer.
20. The method of claim 1 , wherein the first and second electrodes are mounted on a substrate via one of a solder weld and a metal interconnect.
21. The method of claim 20 , further comprising forming an insulating coating on the substrate.
22. The method of claim 20 , wherein the substrate is formed by depositing one selected from a group consisting of a metal, a semiconductor material, and a ceramic.
23. The method of claim 22 , wherein the metal includes at least one selected from a group consisting of Cu, Mo, W, and Al, wherein the semiconductor material includes at least one selected from a group consisting of Si, GaAs, GaP, InP, and Ge, and wherein the ceramic includes at least one selected from a group consisting of Al 2 O 3 and AlN.