Light-emitting-diode chip comprising a sequence of GAN-based epitaxial layers which emit radiation and a method for producing the same

• US 7,939,844 B2
• Filed: 05/30/2007
• Issued: 05/10/2011
• Est. Priority Date: 05/26/2000
• Status: Expired due to Term

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: OSRAM GmbH (Ams-Osram AG)
• Inventors: Jacob, Ulrich, Lugauer, Hans-Jürgen, Mundbrod-Vangerow, Manfred, Hahn, Berthold
• Primary Examiner(s): Jackson, Jr.; Jerome
• Application Number:
  US11/755,284
• Publication Number:
  US 20070221936A1
• Time in Patent Office: 1,441 Days
• Field of Search: 257/99
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01067 Holmium [Ho]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

A light-emitting diode chip (1) comprises a GaN-based, radiation-emitting epitaxial layer sequence (3), an active region (19), an n-doped layer (4) and a p-doped layer (5). The p-doped layer (5) is provided, on its main surface (9) facing away from the active region (19), with a reflective contact metallization (6) comprising a radioparent contact layer (15) and a reflective layer (16). Methods for fabricating LED chips of this type by thin-film technology are provided, as are LED components containing such LED chips.

Claims

1. A light-emitting diode chip comprising:

a GaN-based, radiation-emitting epitaxial layer sequence comprising an active region, an n-doped layer and a p-doped layer; and

a reflective contact metallization assigned to said p-doped layer, said reflective contact metallization configured to reflect radiation emitted by the radiation-emitting layer sequence and comprising;

a radiation permeable contact layer and a reflective layer, wherein said radiation permeable contact layer is arranged between said p-doped layer and said reflective layer, and wherein said reflective layer comprises Ag,

wherein the radiation-emitting epitaxial layer sequence is free of a growth substrate.

2. The light-emitting diode chip as recited in claim 1, wherein said contact layer comprises at least one of the metals Pt, Pd and Cr, is composed of one of said metals, or is composed of an alloy of at least two of said metals.

3. The light-emitting diode chip as recited in claim 1, wherein the thickness of said contact layer is 10 nm or less.

4. The light-emitting diode chip as recited in claim 1, wherein said contact layer is a non-closed layer particularly having an island-like or a net-like structure or a combination thereof.

5. The light-emitting diode chip as recited in claim 1, wherein the thickness of said contact layer is 10 nm or more.

6. The light-emitting diode chip as recited in claim 1, wherein said reflective layer is composed at least in part of a material from the group of materials including PtAg alloy and PdAg alloy.

7. The light-emitting diode chip as recited in claim 1, wherein said reflective layer covers more than 50% of the main surface of said p-doped layer facing away from said active region.

8. The light-emitting diode chip as recited in claim 7, wherein said reflective layer covers the entire main surface of said p-doped layer facing away from said active region.

9. The light-emitting diode chip as recited in claim 1, wherein said reflective contact metallization comprises, on its side facing away from said radiation-emitting epitaxial layer sequence, an additional metal layer particularly comprising substantially Au or Al.

10. The light-emitting diode chip as recited in claim 1, wherein an n-doped layer is provided on its main surface facing away from a p-type layer with an n-contact layer that covers only a portion of said main surface, and wherein the decoupling of light from said chip takes place through the bare region of said main surface of said n-type layer and through the sides of the chip.

11. The light-emitting diode chip as recited in claim 1, wherein said chip comprises an epitaxial layer sequence with a reflective contact metallization and an additional contact metallization.

12. The light-emitting diode chip as recited in claim 11, wherein the thickness of said epitaxial layer sequence is 30 μ

m or less.

13. A light-emitting diode component comprising a light-emitting diode chip as recited in claim 1, wherein said epitaxial layer sequence is connected in a thermally conductive manner to a heat sink via said reflective contact metallization.

14. The light-emitting diode component comprising a light-emitting diode chip as recited in claim 1, said chip being mounted on a heat-conducting chip-mounting area of an LED package, particularly on a leadframe or a track of said LED package, wherein said reflective contact metallization is disposed on said chip mounting surface.

15. A method for fabricating a light-emitting diode chip as recited in claim 1, wherein:

(a) said epitaxial layer sequence is grown on a growth substrate so that said p-doped layer faces away from said growth substrate,

(b) said reflective contact metallization is deposited on said p-doped layer, and

(c) said growth substrate is removed.

16. A method for fabricating a light-emitting diode chip as recited in claim 11, wherein:

(a) said epitaxial layer sequence is grown on said growth substrate so that said p-doped layer faces away from said growth substrate,

(b) said reflective contact metallization is deposited on said p-doped layer, and

(c) said growth substrate is removed.

17. The light-emitting diode chip as recited in claim 4, wherein the contact layer enables the reflective layer to be in direct contact, at least in part, with the p-doped layer.

18. The light-emitting diode chip as recited in claim 1, wherein the radiation permeable contact layer is not configured to reflect radiation emitted by the radiation-emitting layer sequence, the radiation-permeable contact layer being in direct contact with the p-doped layer.

19. A light-emitting diode chip comprising:

a GaN-based, radiation-emitting epitaxial layer sequence comprising an active region, an n-doped layer and a p-doped layer; and

a reflective contact metallization assigned to said p-doped layer, said reflective contact metallization configured to reflect radiation emitted by the radiation-emitting layer sequence and comprising;

a radiation permeable contact layer and a reflective layer, wherein said radiation permeable contact layer is arranged between said p-doped layer and said reflective layer, and wherein said reflective layer covers more than 50% of the main surface of said p-doped layer facing away from said active region,

wherein the radiation-emitting epitaxial layer sequence is free of a growth substrate.

20. The light-emitting diode chip as recited in claim 19, wherein said contact layer comprises at least one of the metals Pt, Pd and Cr, is composed of one of said metals, or is composed of an alloy of at least two of said metals.

21. The light-emitting diode chip as recited in claim 19, wherein the thickness of said contact layer is 10 nm or less.

22. The light-emitting diode chip as recited in claim 19, wherein said contact layer is a non-closed layer particularly having an island-like or a net-like structure or a combination thereof.

23. The light-emitting diode chip as recited in claim 19, wherein said contact layer substantially comprises at least one material from the group of materials including indium tin oxide (ITO) and ZnO.

24. The light-emitting diode chip as recited in claim 23, wherein the thickness of said contact layer is 10 nm or more.

25. The light-emitting diode chip as recited in claim 19, wherein said reflective layer comprises Ag.

26. The light-emitting diode chip as recited in claim 19, wherein said reflective layer is composed at least in part of a material from the group of materials including PtAg alloy and PdAg alloy.

27. The light-emitting diode chip as recited in claim 19, wherein said reflective layer covers the entire main surface of said p-doped layer facing away from said active region.

28. The light-emitting diode chip as recited in claim 19, wherein said reflective contact metallization comprises, on its side facing away from said radiation-emitting epitaxial layer sequence, an additional metal layer particularly comprising substantially Au or Al.

29. The light-emitting diode chip as recited in claim 19, wherein an n-doped layer is provided on its main surface facing away from a p-type layer with an n-contact layer that covers only a portion of said main surface, and wherein the decoupling of light from said chip takes place through the bare region of said main surface of said n-type layer and through the sides of the chip.

30. The light-emitting diode chip as recited in claim 19, wherein said chip comprises an epitaxial layer sequence with a reflective contact metallization and an additional contact metallization.

31. The light-emitting diode chip as recited in claim 30, wherein the thickness of said epitaxial layer sequence is 30 μ

m or less.

32. A light-emitting diode component comprising a light-emitting diode chip as recited in claim 19, wherein said epitaxial layer sequence is connected in a thermally conductive manner to a heat sink via said reflective contact metallization.

33. The light-emitting diode component comprising a light-emitting diode chip as recited in claim 19, said chip being mounted on a heat-conducting chip-mounting area of an LED package, particularly on a leadframe or a track of said LED package, wherein said reflective contact metallization is disposed on said chip mounting area.

34. The light-emitting diode chip as recited in claim 22, wherein the contact layer enables the reflective layer to be in direct contact, at least in part, with the p-doped layer.

35. The light-emitting diode chip as recited in claim 19, wherein the radiation permeable contact layer is not configured to reflect radiation emitted by the radiation-emitting layer sequence, the radiation-permeable contact layer being in direct contact with the p-doped layer.