Luminescent ceramic for a light emitting device

• US 10,290,775 B2
• Filed: 07/11/2017
• Issued: 05/14/2019
• Est. Priority Date: 06/03/2004
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Inventors: Mueller, Gerd O., Mueller-Mach, Regina B., Krames, Michael R., Schmidt, Peter J., Bechtel, Hans-Helmut, Meyer, Joerg, de Graaf, Jan, Kop, Theo Arnold
• Primary Examiner(s): Ngo, Ngan V
• Application Number:
  US15/647,092
• Publication Number:
  US 20170309791A1
• Time in Patent Office: 672 Days
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• 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 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/6027 Slip casting
• CPC Class Codes: C04B 2235/662 Annealing after sintering
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C04B 35/547 based on sulfides or selenides or tellurides
• CPC Class Codes: C04B 35/584 based on silicon nitride
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• 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 35/64 Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: C09K 11/7774 Aluminates
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 2933/0066 : relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 2933/0075 : relating to heat extraction or cooling elements
• CPC Class Codes: H01L 33/007 : comprising nitride compounds
• CPC Class Codes: H01L 33/0075 : comprising nitride compounds
• CPC Class Codes: H01L 33/0093 : Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/06 : within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/12 : with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/32 : containing nitrogen
• CPC Class Codes: H01L 33/50 : Wavelength conversion elements
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: H01L 33/505 : characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/508 : having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/641 : characterized by the materials
• CPC Class Codes: H01L 33/644 : in intimate contact or integrated with parts of the device other than the semiconductor body

Abstract

A semiconductor light emitting device comprising a light emitting layer disposed between an n-type region and a p-type region is combined with a ceramic layer which is disposed in a path of light emitted by the light emitting layer. The ceramic layer is composed of or includes a wavelength converting material such as a phosphor. Luminescent ceramic layers according to embodiments of the invention may be more robust and less sensitive to temperature than prior art phosphor layers. In addition, luminescent ceramics may exhibit less scattering and may therefore increase the conversion efficiency over prior art phosphor layers.

Claims

1. A device comprising:

a semiconductor light emitting device;

a ceramic layer comprising a first wavelength converting material disposed over the semiconductor light emitting device;

a glass layer disposed directly on and contacting the semiconductor light emitting device; and

a second wavelength converting material disposed over the semiconductor light emitting device.

2. The device of claim 1 wherein the glass layer attaches the ceramic layer to the semiconductor light emitting device.

3. The device of claim 1 wherein the glass layer is disposed between the ceramic layer and the semiconductor light emitting device.

4. The device of claim 1 wherein the glass layer has an index of refraction greater than 1.8.

5. The device of claim 1 wherein the second wavelength converting material is disposed in a transparent material.

6. The device of claim 1 wherein the second wavelength converting material is a conformal layer.

7. The device of claim 1 wherein the ceramic layer is disposed between the semiconductor light emitting device and the second wavelength converting material.

8. The device of claim 1 wherein the ceramic layer is a solid agglomerate of phosphor particles substantially free of hinder material.

9. The device of claim 1 wherein the glass layer is selected from the group consisting of high index optical glass, Schott glass SF59, Schott glass LaSF 3, Schott glass LaSF N18, and mixtures thereof.

10. The device of claim 1 wherein the glass layer is sol-gel glass.

11. The device of claim 10 wherein the sol-gel glass comprises one or more materials selected from the group consisting of oxides of titanium, cerium, lead, gallium, bismuth, cadmium, zinc, barium, and aluminum.

12. The device of claim 1 wherein the semiconductor light emitting device is a III-nitride light emitting diode and the ceramic layer comprises Y₃Al₅O₁₂:

Ce³⁺.