Multi-Grain Luminescent Ceramics for Light Emitting Devices

• US 20080149956A1
• Filed: 12/22/2006
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.), Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.), Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Bechtel, Hans-Helmut, Schmidt, Peter J., Krames, Michael R., Mueller-Mach, Regina B., Mueller, Gerd O.
• Granted Patent: US 7,902,564 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• 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 2235/3409 Boron oxide, borates, boric acids, or oxide forming salts thereof, e.g. borax
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint glass constituents C04B2235/36
• CPC Class Codes: C04B 2235/652 Reduction treatment C04B2235/664 takes precedence
• CPC Class Codes: C04B 2235/658 Atmosphere during thermal treatment
• CPC Class Codes: C04B 2235/6582 Hydrogen containing atmosphere
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/77748 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• 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 2933/0091 : Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/382 : the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder
• CPC Class Codes: Y10S 250/909 : Methods and apparatus ancillary to stimulable phosphor systems

Abstract

A ceramic body is disposed in a path of light emitted by a light source. The light source may include a semiconductor structure comprising a light emitting region disposed between an n-type region and a p-type region. The ceramic body includes a plurality of first grains configured to absorb light emitted by the light source and emit light of a different wavelength, and a plurality of second grains. For example, the first grains may be grains of luminescent material and the second grains may be grains of a luminescent material host matrix without activating dopant.

Claims

1. A device comprising:

a light source; and

a ceramic body disposed in a path of light emitted by the light source, wherein the ceramic body comprises;

a plurality of first grains configured to absorb first light emitted by the light source and emit second light of a different wavelength from the first light; and

a plurality of second grains.

2. The device of claim 1 wherein the light source comprises a semiconductor structure comprising a light emitting region disposed between an n-type region and a p-type region.

3. The device of claim 2 wherein the ceramic body is configured to scatter light emitted by the light emitting region.

4. The device of claim 2 wherein the second grains are transparent to the first light.

5. The device of claim 2 wherein:

the first grains comprise a host matrix and an activating dopant; and

the second grains comprise the host matrix without any activating dopant.

6. The device of claim 5 wherein the activating dopant is Ce.

7. The device of claim 5 wherein the activating dopant is Eu.

8. The device of claim 2 wherein the first grains are dispersed over a plurality of regions in the ceramic body, wherein the plurality of regions are separated by second grains.

9. The device of claim 8 wherein:

the first grains comprise a host matrix and an activating dopant; and

within a region of first grains, a first grain proximate a center of the region has a higher concentration of activating dopant than a first grain proximate an edge of the region.

10. The device of claim 2 wherein:

the first grains comprise a host matrix and a first activating dopant; and

the second grains comprise the host matrix and a second activating dopant.

11. The device of claim 10 wherein the second grains are configured to absorb first light and emit third light of a different wavelength from the first light and the second light.

12. The device of claim 10 wherein the ceramic body further comprises third grains comprising the host matrix without any activating dopant.

13. The device of claim 10 wherein:

the first activating dopant is Ce; and

the second activating dopant is Eu.

14. The device of claim 10 wherein the host matrix is Ca₁₋

x−

yM_yAl<sub>1+a−

b+x</sub>B_bSi<sub>1−

a</sub>N<sub>3−

a</sub>O_a, where M=(Mg, Sr, Ba), B=(B, Ga), 0.001≦

x≦

0.02, 0≦

y≦

1, 0.0005≦

a≦

1, 0≦

b≦

1.

15. The device of claim 10 wherein the host matrix is (Lu₁₋

x−

y−

a−

bY_xGd_y)₃(Al<sub>1−

z−

u</sub>Ga_zSi_u)₅O<sub>12−

u</sub>N_u wherein 0≦

x≦

1, 0≦

y≦

1, 0<

z≦

0.1, 0≦

u≦

0.2, 0<

a≦

0.2 and 0<

b≦

0.1.

16. The device of claim 2 wherein the ceramic body is disposed on a surface of the semiconductor structure.

17. The device of claim 2 wherein the first light is blue and the second light is yellow or green.

18. The device of claim 2 wherein the first grains are (Lu₁₋

x−

y−

a−

bY_xGd_y)₃(Al<sub>1−

z−

u</sub>Ga_zSi_u)₅O<sub>12−

u</sub>N_u;

Ce_aPr_b wherein 0≦

x≦

1, 0≦

y≦

1, 0<

z≦

0.1, 0≦

u≦

0.2, 0<

a≦

0.2 and 0<

b≦

0.1.

19. The device of claim 2 wherein the first light is blue and the second light is red.

20. The device of claim 2 wherein the first grains are (Ca₁₋

x−

y−

zSr_xBa_yMg_z)<sub>1−

n</sub>Al_1+a+bSi<sub>1−

a−

b</sub>N<sub>3−

b</sub>O_b;

M_n wherein 0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1, 0≦

a≦

1, 0≦

b≦

1, 0≦

n≦

1, a≦

n, and M is a metal selected from the group of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or mixtures thereof.

21. The device of claim 2 wherein the first grains are Ca(Al,Si)₂N₃.

22. The device of claim 2 further comprising a wavelength converting material disposed in a path of light emitted by the light emitting region, the wavelength converting material being configured to absorb the first light and emit third light of a different wavelength from the first light.

23. The device of claim 22 wherein:

the ceramic body is a first ceramic body; and

the wavelength converting material is included in a second ceramic body.

24. The device of claim 2 further comprising:

first and second contacts electrically connected to the n-type region and the p-type region; and

a cover disposed over the light emitting region.

25. The device of claim 2 wherein the semiconductor structure comprises a plurality of III-nitride semiconductor layers.