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 disposed on one side of the epitaxial layer structure. The epitaxial layer structure includes a transparent ohmic contact layer having a root-means-square (RMS) roughness less than about 3 nm at a surface whereon the second electrode is formed. The epitaxial layer structure includes a p-type epitaxial layer and a n-type epitaxial layer, wherein the n-type epitaxial layer is coupled between the first electrode and the p-type epitaxial layer, and the p-type epitaxial layer is between the second electrode and the n-type epitaxial layer. The first electrode is located on the n-type epitaxial layer.
1. A light emitting diode, comprising:
an epitaxial layer structure;
a first electrode; and
a second electrode,
wherein the first and second electrodes are disposed on one side of the epitaxial layer structure, and the epitaxial layer structure comprises a transparent ohmic contact layer having a root-means-square (RMS) roughness less than about 3 nm at a surface whereon the second electrode is formed,
wherein the epitaxial layer structure includes a p-type epitaxial layer and a n-type epitaxial layer, wherein the n-type epitaxial layer is coupled between the first electrode and the p-type epitaxial layer, and the p-type epitaxial layer is between the second electrode and the n-type epitaxial layer, and wherein the first electrode is located on the n-type epitaxial layer.
2. The light emitting diode of claim 1 , wherein the light emitting diode comprises a flip-chip structure.
3. The light emitting diode of claim 1 , wherein the first electrode is an n-type electrode and the second electrode is a p-type electrode.
4. The light emitting diode of claim 1 , wherein each of the p-type and n-type epitaxial layers comprises GaN.
5. The light emitting diode of claim 1 , wherein each of the first and second electrodes includes a metal selected from a group of consisting of Ag, Pt, Ni, Cr, Ti, Al, Pd, W, Ru, Rh, Mo, and their alloys.
6. The light emitting diode of claim 1 , wherein the p-type epitaxial layer is deposited via a MOCVD (Metal-Organic Chemical Vapor Deposition) using a metal-organic compound solution.
7. The light emitting diode of claim 1 , wherein the p-type epitaxial layer is formed at a temperature no less than 950° C. at a growth rate no more than 150 Å/mim.
8. The light emitting diode of claim 1 , further comprising a substrate, wherein the first and second electrodes are coupled to the substrate.
9. The light emitting diode of claim 8 , wherein the substrate comprises first and second metal contact pads, the first electrode being coupled to the first metal contact pad and the second electrode being mounted to the second metal contact pad.
10. The light emitting diode of claim 9 , wherein each of the first and second electrodes are respectively coupled to the first and second metal contact pads via solder welds or metal interconnects.
11. The light emitting diode of claim 9 , wherein the substrate is electrically insulating between the first and second metal contact pads.
12. The light emitting diode of claim 9 , wherein the substrate comprises a coating arranged to electrically isolate the first and second metal contact pads.
13. The light emitting diode of claim 8 , wherein the substrate is selected from a group consisting of a metal, a semiconductor material, and a ceramic.
14. The light emitting diode of claim 13 , 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.