Facet extraction LED and method for manufacturing the same

Abstract

A facet extraction LED improved in light extraction efficiency and a manufacturing method thereof. A substrate is provided. A light emitting part includes an n-type semiconductor layer, an active layer and a p-type semiconductor layer sequentially stacked on the substrate. A p-electrode and an n-electrode are connected to the p-type semiconductor layer and the n-type semiconductor layer, respectively. The p- and n-electrodes are formed on the same side of the LED. The light emitting part is structured as a ring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating a conventional facet extraction LED;

FIG. 2 is a perspective view illustrating a facet extraction LED according to a first embodiment of the invention;

FIG. 3 is a plan view illustrating the facet extraction LED of FIG. 2;

FIG. 4 is a side cross-sectional view illustrating a facet extraction LED cut along the line XX′ of FIG. 3;

FIG. 5 is a partial plan view for explaining decrease in total reflection of the facet extraction LED shown in FIG. 2;

FIG. 6 is a plan view illustrating a facet extraction LED according to a second embodiment of the invention;

FIG. 7 is a side cross-sectional view illustrating a facet extraction LED according to a third embodiment of the invention;

FIG. 8 is a perspective view illustrating a facet extraction LED according to a fourth embodiment of the invention;

FIG. 9 is a side cross-sectional view illustrating a facet extraction LED according to a fifth embodiment of the invention;

FIG. 10 illustrates a facet extraction LED mounted in a reflective cup of a package according to an embodiment of the invention;

FIG. 11 illustrates a facet extraction LED mounted in a reflective cup of a package according to another embodiment of the invention;

FIG. 12 is an energy band diagram illustrating a facet extraction LED according to further another embodiment of the invention;

FIG. 13 is a side cross-sectional view for explaining a method for manufacturing a facet extraction LED according to an embodiment of the invention; and

FIG. 14 is a side cross-sectional view for explaining a method for manufacturing a facet extraction LED according to another embodiment of the invention.

Claims

1. A facet extraction light emitting diode comprising: a substrate;a light emitting part including an n-type semiconductor layer, an active layer and a p-type semiconductor layer sequentially stacked on the substrate; anda p-electrode and an n-electrode connected to the p-type semiconductor layer and the n-type semiconductor layer, respectively, wherein the p- and n-electrodes are formed on the same side of the diode,wherein the light emitting part comprises a ring structure.

2. The facet extraction light emitting diode according to claim 1, wherein the ring structure has outer and inner facets crossing the active layer, the outer facet extracting a greater amount of light than the inner facet.

3. The facet extraction light emitting diode according to claim 1, wherein each of the n-type semiconductor layer, the active layer and the p-type semiconductor layer comprises a group III-V compound semiconductor material.

4. The facet extraction light emitting diode according to claim 1, further comprising an anti-reflection film formed on the outer facet of the ring structure.

5. The facet extraction light emitting diode according to claim 4, wherein the anti-reflection film has a reflectivity ranging from 0% to 5% with respect to light from the active layer.

6. The facet extraction light emitting diode according to claim 1, further comprising a reflective film formed on an inner facet of the ring structure.

7. The facet extraction light emitting diode according to claim 6, wherein the reflective film has a reflectivity ranging from 90% to 100% with respect to light from the active layer.

8. The facet extraction light emitting diode according to claim 1, wherein the ring structure has a circular outline.

9. The facet extraction light emitting diode according to claim 1, wherein the ring structure has a polygonal outline.

10. The facet extraction light emitting diode according to claim 1, comprising a flip-chip LED.

11. The facet extraction light emitting diode according to claim 1, wherein the ring structure satisfies a following relationship: 5≦W/L≦10,000,where L is a distance between the outer and inner facets, and W is an outer peripheral length of the active layer on the outer facet.

12. The facet extraction light emitting diode according to claim 1, wherein the distance between the outer and inner facets of the ring structure ranges from 1 μm to 100 μm.

13. The facet extraction light emitting diode according to claim 1, wherein the ring structure has protrusions and indentations on the outer facet.

14. The facet extraction light emitting diode according to claim 1, wherein the substrate comprises a sapphire substrate.

15. The facet extraction light emitting diode according to claim 1, wherein the substrate comprises a conductive substrate.

16. The facet extraction light emitting diode according to claim 1, wherein the conductive substrate comprises a GaN-based substrate.

17. The facet extraction light emitting diode according to claim 1, wherein the n-electrode is surrounded by the ring structure.

18. The facet extraction light emitting diode according to claim 17, wherein the n-electrode is disposed on the n-type semiconductor layer, surrounded by the ring structure.

19. The facet extraction light emitting diode according to claim 17, wherein the substrate comprises a conductive substrate, and wherein the n-electrode surrounded by the ring structure is in direct contact with the substrate.

20. The facet extraction light emitting diode according to claim 1, wherein the outer and inner facets of the ring structure are inclined with respect to a stacking direction of the semiconductor layers in such a fashion that a distance between the outer and inner facets increases toward the substrate.

21. The facet extraction light emitting diode according to claim 1, wherein the n- and p-type semiconductor layers and the active layer comprise a separate confinement heterostructure.

22. A method for manufacturing a light emitting diode comprising: sequentially forming an n-type semiconductor layer, an active layer and a p-type semiconductor layer on a substrate;forming a p-electrode with a ring pattern on the p-type semiconductor layer;selectively etching the p-type semiconductor layer, the active layer and the n-type semiconductor layer to form a light emitting part of a ring structure under the p-electrode; andforming an n-electrode to be surrounded by the light emitting part.

23. The method according to claim 22, wherein the step of forming the light emitting part of the ring structure comprises partially etching a portion of the n-type semiconductor layer, in a thickness direction, in such a fashion that a remaining portion of the etched n-type semiconductor layer portion is surrounded by the light emitting part.

24. The method according to claim 23, wherein the n-electrode is formed on the remaining portion of the n-type semiconductor layer surrounded by the light-emitting part.

25. The method according to claim 22, wherein the substrate comprises a conductive substrate, and wherein the step of forming the light emitting part of the ring structure comprises entirely etching a portion of the n-type semiconductor layer, in a thickness direction, so that the portion of the n-type semiconductor layer is completely removed in a region surrounded by the light emitting part.

26. The method according to claim 25, wherein the n-electrode is surrounded by the light emitting part and is in direct contact with the substrate.

27. The method according to claim 22, further comprising forming an anti-reflection film on the outer facet of the ring structure.

28. The method according to claim 22, further comprising forming a reflective film on the inner facet of the ring structure.