Diode having high brightness and method thereof
View Patent ↗A light emitting diode includes a transparent substrate and a GaN buffer layer on the transparent substrate. An n-GaN layer is formed on the buffer layer. An active layer is formed on the n-GaN layer. A p-GaN layer is formed on the active layer. A p-electrode is formed on the p-GaN layer and an n-electrode is formed on the n-GaN layer. A reflective layer is formed on a second side of the transparent substrate. Also, a cladding layer of AlGaN is between the p-GaN layer and the active layer.
1. A light emitting diode comprising:
a transparent substrate;
a buffer layer on a first surface of the transparent substrate;
an n-GaN layer on the buffer layer;
an active layer on the n-GaN layer;
a p-GaN layer on the active layer;
a p-electrode on the p-GaN layer;
a p-transparent contact between the p-electrode and the p-GaN layer, wherein the p-transparent contact includes indium-tin-oxide;
an n-electrode on the n-GaN layer; and
a reflective layer on a second side of the transparent substrate.
2. The light emitting diode according to claim 1 , wherein the second side of the transparent substrate has a polished surface.
3. The light emitting diode according to claim 1 , wherein the second side of the transparent substrate has been polished by mechanical polishing.
4. The light emitting diode according to claim 1 , wherein the second side of the transparent substrate has been polished by dry etching.
5. The light emitting diode according to claim 1 , wherein the second side of the transparent substrate has been polished by mechanical polishing and dry etching.
6. The light emitting diode according to claim 1 , wherein the second side of the transparent substrate has undergone back lapping.
7. The light emitting diode according to claim 1 , wherein the second side of the transparent substrate has undergone back lapping and is polished by mechanical polishing.
8. The light emitting diode according to claim 1 , wherein the reflective layer includes aluminum.
9. The light emitting diode according to claim 1 , wherein the reflective layer includes a metal selected from the group consisting of aluminum, gold, palladium, titanium, indium, nickel and platinum.
10. The light emitting diode according to claim 9 , wherein the reflective layer includes aluminum having a concentration of about 99.999% or higher.
11. The light emitting diode according to claim 1 , wherein the reflective layer includes aluminum of about 3000 Å.
12. The light emitting diode according to claim 1 , wherein the reflective layer substantially entirely covers the second side of the substrate.
13. The light emitting diode according to claim 1 , wherein the transparent substrate further comprises a buffer layer including GaN.
14. The light emitting diode according to claim 1 , wherein the transparent substrate further comprises a buffer layer including aluminum nitride (AlN).
15. The light emitting diode according to claim 1 , wherein the transparent substrate includes a material selected from the group consisting of sapphire, zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (SiC) and aluminum nitride (AlN).
16. The light emitting diode according to claim 1 , wherein the transparent substrate includes sapphire.
17. The light emitting diode according to claim 16 , wherein the transparent substrate has a thickness of 350–430 μm.
18. The light emitting diode according to claim 16 , wherein the transparent substrate has a thickness of less than 350 μm.
19. The light emitting diode according to claim 16 , wherein the transparent substrate has a thickness of less than 120 μm.
20. The light emitting diode according to claim 16 , wherein the transparent substrate has a thickness between about 100 μm to 120 μm.
21. the light emitting diode according to claim 1 , further comprising a metal pad on the p-electrode and the n-electrode.
22. The light emitting diode according to claim 22 , wherein the metal pad is about 5000 Å or higher.
23. The light emitting diode according to claim 22 , wherein the metal pad includes Au.
24. The light emitting diode according to claim 1 , wherein the n-electrode includes Ti and Al (Ti/Al).
25. The light emitting diode according to claim 1 , wherein the n-electrode includes a material selected from the group consisting of Ti/Al, Cr/Au and Ti/Au.
26. The light emitting diode according to claim 1 , wherein the p-electrode includes Ni and Au (Ni/Au).
27. The light emitting diode according to claim 1 , wherein the p-electrode includes a material selected from the group consisting of Ni/Au, Pd/Au, Pd/Ni and Pt.
28. The light emitting diode according to claim 1 , wherein the active layer includes AlInGaN.
29. The light emitting diode according to claim 1 , wherein the second surface of the transparent substrate has an average surface roughness of less than 15 nm.
30. The light emitting diode according to claim 1 , wherein the second surface of the transparent substrate has an average surface roughness of less than 6 nm.
31. The light emitting diode according to claim 1 , wherein the second surface of the transparent substrate has an average surface roughness of less than 2 nm.
32. The light emitting diode according to claim 1 , wherein the second surface of the transparent substrate has an average surface roughness of less than 1 nm.
33. The light emitting diode according to claim 1 , further comprising a package housing the light emitting diode.
34. The light emitting diode according to claim 1 , wherein the reflective layer is directly on the second side of the transparent substrate.
35. The light emitting diode according to claim 1 , wherein the active layer includes at least one of a quantum well layer and a double hetero structure.
36. The light emitting diode according to claim 1 , wherein the quantum layer includes a multiple quantum layer.