Light emitting diode having vertical topology and method of making the same
View Patent ↗An LED having vertical topology and a method of making the same is capable of improving a luminous efficiency and reliability, and is also capable of achieving mass productivity. The method includes forming a semiconductor layer on a substrate; forming a first electrode on the semiconductor layer; forming a supporting layer on the first electrode; generating an acoustic stress wave at the interface between the substrate and semiconductor layer, thereby separating the substrate from the semiconductor layer; and forming a second electrode on the semiconductor layer exposed by the separation of the substrate.
1. A light emitting device, comprising: a supporting layer;
a first electrode on the supporting layer, the first electrode including an ohmic electrode and a reflective electrode;
a second electrode on the first electrode;
a semiconductor structure comprising a first surface and a second surface opposite the first surface, the semiconductor structure arranged between the first electrode and the second electrode, wherein the first electrode, relative to the second electrode, is proximate to and aligned with the first surface, and the second electrode, relative to the first electrode, is proximate to and aligned with the second surface;
a light-extraction structure that is part of the second surface of the semiconductor structure; and
a passivation layer disposed on at least one surface of the semiconductor structure,
wherein the first electrode comprises a surface facing the first surface of the semiconductor structure,
wherein the area of the surface of the first electrode and the area of the first surface of the semiconductor structure are different, and wherein the thickness of the reflective electrode is in the range of 300 Å to 5000 Å.
2. The device according to claim 1 , further including a connection metal layer between the supporting layer and the first electrode.
3. The device according to claim 2 , wherein the connection metal layer is a reflective layer.
4. The device according to claim 2 , wherein the connection metal layer has a multi-layer structure.
5. The device according to claim 2 , wherein the connection metal layer is a bonding layer for attaching the supporting layer.
6. The device according to claim 1 , wherein the supporting layer comprises a semiconductor layer.
7. The device according to claim 1 , wherein the semiconductor structure includes:
a p-type semiconductor layer;
an active layer disposed on the p-type semiconductor layer; and
a n-type semiconductor layer disposed on the active layer.
8. The device according to claim 7 , further comprising:
a current diffusion layer including an InGaN layer or an InGaN/GaN superlattice layer, between the p-type semiconductor layer and the first electrode.
9. The device according to claim 1 , wherein the passivation layer includes at least one of SiO 2 , SiN, epoxy-based photoresist, acrylic-based photoresist, SOG, and polyimide.
10. The device according to claim 1 , wherein the thickness of the supporting layer has a value ranging from 50 to 150 μm.
11. The device according to claim 1 , wherein the first electrode has a multi-layer structure.
12. The device according to claim 1 , wherein the passivation layer includes a first passivation layer and a second passivation layer on the first passivation layer.
13. The device according to claim 12 , wherein the first passivation layer is an inorganic layer and the second passivation layer is an organic layer.
14. The device according to claim 2 , wherein the first electrode is electrically connected to the connection metal layer.
15. The device according to claim 1 , wherein the passivation layer extends along the at least one surface of the semiconductor structure to a light emitting surface of the semiconductor structure, and wherein the light emitting surface is proximate to the second electrode.
16. The device according to claim 1 , wherein the supporting layer includes a metallic layer.
17. A light emitting device, comprising:
a supporting layer;
a connection metal layer on the supporting layer;
a first electrode on at least one portion of the connection metal layer; a second electrode;
a semiconductor structure having multi-layers, the semiconductor structure positioned between the first electrode and the second electrode, the semiconductor structure having a first surface and a second surface opposite the first surface, wherein the first electrode, compared to the second electrode, is proximate to the first surface, the second electrode, compared to the first electrode, is proximate to the second surface, and at least a portion of the second surface is configured as a light-extraction structure; and
a passivation layer on the semiconductor structure, wherein the semiconductor structure includes a substantially un-doped semiconductor layer proximate to the second surface.
18. The device according to claim 17 , wherein the supporting layer has an edge portion such that a recess is formed.
19. The device according to claim 17 , further including a metal layer between the passivation layer and the connection metal layer.
20. A light emitting device, comprising:
a supporting layer comprising at least one of semiconductor and metal;
a connection metal layer on the supporting layer;
a first electrode on at least one portion of the connection metal layer;
a semiconductor structure having multi-layers on the first electrode;
a light-extraction structure formed on at least a portion of the semiconductor structure;
a second electrode on the semiconductor structure; and
a passivation layer on the semiconductor structure, wherein the light-extraction structure comprises a photonic crystal that includes randomly positioned unit structures, and wherein the light-extraction structure reflects a photonic crystal having periodically positioned unit structures, wherein the distance between the periodically positioned unit structures substantially equals the average distance between the randomly positioned unit structures.
21. The device according to claim 20 , wherein the passivation layer includes:
a first passivation layer; and
a second passivation layer on the first passivation layer.
22. The device according to claim 1 , wherein the ohmic electrode comprises a transparent conductive oxide layer.
23. The device according to claim 1 , wherein the light-extraction structure is an integral part of the semiconductor structure.
24. The device according to claim 1 , wherein the light-extaction structure comprises unit structures that are formed in a pattern.
25. The device according to claim 17 , wherein the passivation layer is located between the connection metal layer and the semiconductor structure.
26. The device according to claim 17 , wherein the thickness of the supporting layer is in the range of 50 to 150 μm.
27. The device according to claim 17 , wherein at least a portion of the light-extraction structure is formed on the substantially un-doped semiconductor layer.
28. The device according to claim 20 , wherein the thickness of the supporting layer is in the range of 50 to 150 μm.
29. The device according to claim 20 , wherein the passivation layer is located between the connection metal layer and the semiconductor structure.