Wavelength-converted semiconductor light emitting device

• US 20060202105A1
• Filed: 03/14/2005
• Published: 09/14/2006
• Est. Priority Date: 03/14/2005
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Krames, Michael R., Mueller, Gerd O.
• Granted Patent: US 7,341,878 B2
• Time in Patent Office: Days
• US Class Current: 250/208.100
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2237/02 Aspects relating to interlayers, e.g. used to join ceramic articles with other articles by heating
• CPC Class Codes: C04B 2237/06 Oxidic interlayers
• CPC Class Codes: C04B 2237/064 based on alumina or aluminates
• CPC Class Codes: C04B 2237/068 based on refractory oxides, e.g. zirconia
• CPC Class Codes: C04B 2237/08 Non-oxidic interlayers
• CPC Class Codes: C04B 2237/083 Carbide interlayers, e.g. silicon carbide interlayers
• CPC Class Codes: C04B 2237/10 Glass interlayers, e.g. frit or flux
• CPC Class Codes: C04B 2237/12 Metallic interlayers
• CPC Class Codes: C04B 2237/30 Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
• CPC Class Codes: C04B 2237/34 Oxidic
• CPC Class Codes: C04B 2237/343 Alumina or aluminates
• CPC Class Codes: C04B 2237/36 Non-oxidic
• CPC Class Codes: C04B 2237/365 Silicon carbide
• CPC Class Codes: C04B 2237/366 Aluminium nitride
• CPC Class Codes: C04B 2237/368 Silicon nitride
• CPC Class Codes: C04B 2237/52 : Pre-treatment of the joining surfaces, e.g. cleaning, machining
• CPC Class Codes: C04B 2237/525 : by heating
• CPC Class Codes: C04B 2237/704 : of one or more of the ceramic layers or articles
• CPC Class Codes: C04B 2237/708 : of one or more of the interlayers
• CPC Class Codes: C04B 2237/76 : Forming laminates or joined articles comprising at least one member in the form other than a sheet or disc, e.g. two tubes or a tube and a sheet or disc
• CPC Class Codes: C04B 35/44 : based on aluminates
• CPC Class Codes: C04B 35/495 : based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
• CPC Class Codes: C04B 35/6268 : characterised by the applied pressure or type of atmosphere, e.g. in vacuum, hydrogen or a specific oxygen pressure
• CPC Class Codes: C04B 35/62805 : Oxide ceramics
• CPC Class Codes: C04B 35/62807 : Silica or silicates
• CPC Class Codes: C04B 35/62813 : Alumina or aluminates
• CPC Class Codes: C04B 35/645 : Pressure sintering
• CPC Class Codes: C04B 37/001 : directly with other burned ceramic articles
• CPC Class Codes: C04B 37/005 : consisting of glass or ceramic material
• CPC Class Codes: C04B 37/006 : consisting of metals or metal salts
• CPC Class Codes: C04B 37/008 : by means of an interlayer consisting of an organic adhesive, e.g. phenol resin or pitch
• CPC Class Codes: C04B 37/026 : consisting of metals or metal salts
• CPC Class Codes: H01L 2224/0554 : External layer
• CPC Class Codes: H01L 2224/0555 : Shape
• CPC Class Codes: H01L 2224/0556 : Disposition
• CPC Class Codes: H01L 2224/05568 : the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 : Single external layer
• CPC Class Codes: H01L 2224/05599 : Material
• CPC Class Codes: H01L 2224/14 : of a plurality of bump connectors
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• 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 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/0093 : Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/08 : with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder

Abstract

A material such as a phosphor is optically coupled to a semiconductor structure including a light emitting region disposed between an n-type region and a p-type region, in order to efficiently extract light from the light emitting region into the phosphor. The phosphor may be phosphor grains in direct contact with a surface of the semiconductor structure, or a ceramic phosphor bonded to the semiconductor structure, or to a thin nucleation structure on which the semiconductor structure may be grown. The phosphor is preferably highly absorbent and highly efficient. When the semiconductor structure emits light into such a highly efficient, highly absorbent phosphor, the phosphor may efficiently extract light from the structure, reducing the optical losses present in prior art devices.

Claims

1. A method comprising:

providing a structure comprising;

a ceramic body including a phosphor, the phosphor being configured to absorb light of a first peak wavelength and emit light of a second peak wavelength; and

a nucleation structure bonded to a surface of the ceramic body; and

growing on the nucleation structure a semiconductor structure comprising a light emitting region disposed between an n-type region and a p-type region, the light emitting region being configured to emit light of the first peak wavelength;

wherein prior to growing, the nucleation structure has a thickness less that one hundred microns.

2. The method of claim 1 wherein a bond between the ceramic body and the nucleation structure is substantially free of metal or adhesives.

3. The method of claim 1 wherein providing a structure comprises pressing the ceramic body and the nucleation structure together at a temperature greater than 500°

C. and a pressure greater than 5 psi.

4. The method of claim 1 wherein the nucleation structure is selected from the group of GaN, AlN, SiC, and Al₂O₃.

5. The method of claim 1 wherein providing a structure comprises:

providing a nucleation structure formed on a substrate;

bonding the ceramic body to the nucleation structure; and

after bonding, removing the substrate.

6. The method of claim 1 further comprising:

etching the semiconductor structure to expose portions of both the n-type region and the p-type region; and

forming contacts on each of the n-type region and the p-type region.

7. The method of claim 6 wherein at least one of the contacts is reflective.

8. The method of claim 1 wherein the ceramic body is shaped into a lens.

9. The method of claim 1 wherein a surface of the ceramic body is textured or roughened.

10. The method of claim 1 wherein the ceramic body is transparent.

11. The method of claim 1 wherein the ceramic body is opaque.

12. The method of claim 1 wherein prior to growing, the nucleation structure has a thickness less than ten microns.

13. The method of claim 1 wherein prior to growing, the nucleation structure has a thickness less than one micron.

14. The method of claim 1 wherein the structure further comprises a bonding layer disposed between the nucleation structure and the ceramic body.

15. A method comprising:

providing a ceramic body including a phosphor, the phosphor being configured to absorb light of a first peak wavelength and emit light of a second peak wavelength;

providing a semiconductor structure formed on a growth substrate, the semiconductor structure comprising a light emitting region disposed between an n-type region and a p-type region, the light emitting region being configured to emit light of the first peak wavelength;

bonding the ceramic body to a surface of the semiconductor structure; and

after bonding, removing the growth substrate.

16. The method of claim 15 wherein the p-type region is grown over the growth substrate prior to growing the n-type region.

17. The method of claim 16 further comprising annealing the semiconductor structure after removing the growth substrate.

18. The method of claim 15 wherein the surface of the semiconductor structure bonded to the ceramic body is a surface of the n-type region.

19. The method of claim 15 further comprising providing a bonding layer between the semiconductor structure and the ceramic body.

20. A light emitting device comprising:

a luminescent material, in direct contact with one of the plurality of layers, wherein at a wavelength of light emitted by the light emitting region, the imaginary component k of a refractive index of the luminescent material is greater than 0.01.

21. The light emitting device of claim 20 wherein k is greater than 0.1.

22. The light emitting device of claim 20 wherein the light emitting region comprises III-nitride material.

23. The light emitting device of claim 20 wherein the luminescent material comprises phosphor.

24. The light emitting device of claim 23 wherein the luminescent material comprises a ceramic phosphor.

25. The light emitting device of claim 23 wherein the luminescent material comprises phosphor grains.

26. The light emitting device of claim 25 further comprising a transparent material disposed over the phosphor grains, the transparent material having an index of refraction greater than 1.7.

27. The light emitting device of claim 26 wherein the transparent material comprises glass.

28. The light emitting device of claim 27 wherein the glass comprises a sol-gel glass.

29. The light emitting device of claim 26 further comprising nanoparticles having diameters between about 2 nm to about 50 nm disposed in the transparent material.

30. The light emitting device of claim 25 wherein a surface one of the plurality of layers in direct contact with the phosphor grains is textured or roughened.

31. The light emitting device of claim 20 wherein:

the semiconductor structure is bonded to a package element having a lateral extent exceeding a lateral extent of the semiconductor structure; and

the package element is separated from the luminescent material by less than one hundred microns.

32. A structure comprising:

a ceramic body; and

a nucleation structure thinner than one hundred microns; and

a bonded interface that connects the ceramic body to the nucleation structure, the bonded interface being disposed between the ceramic body and the nucleation layer;

wherein;

the nucleation structure is configured such that an epitaxial structure may be grown on the nucleation structure; and

any separation between the ceramic body and the nucleation structure is less than one hundred microns.

33. The structure of claim 32 further comprising a semiconductor structure grown on the nucleation structure, the semiconductor structure comprising a light emitting region disposed between an n-type region and a p-type region, the light emitting region being configured to emit light of the first peak wavelength, wherein the nucleation structure is disposed between the semiconductor structure and the ceramic body.

34. The structure of claim 33 the ceramic body comprises a phosphor configured to absorb light of a first peak wavelength and emit light of a second peak wavelength.

35. The structure of claim 33 wherein the nucleation structure is selected from the group of GaN, AlN, SiC, and Al₂O₃.

36. A structure comprising:

a package element;

a ceramic body; and

a semiconductor structure disposed between and connected to the ceramic body and the package element, the semiconductor structure comprising a light emitting region disposed between an n-type region and a p-type region, the light emitting region being configured to emit light of the first peak wavelength;

wherein the package element is separated from the ceramic body by less than one hundred microns and the package element has a lateral extent exceeding a lateral extent of the semiconductor structure.

37. The structure of claim 36 wherein the ceramic body comprises a phosphor configured to absorb light of a first peak wavelength and emit light of a second peak wavelength.