Gallium-substituted yttrium aluminum garnet phosphor and light emitting devices including the same

• US 8,747,697 B2
• Filed: 06/07/2011
• Issued: 06/10/2014
• Est. Priority Date: 06/07/2011
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Clatterbuck, David, Collins, Brian Thomas
• Primary Examiner(s): Koslow, Carol M
• Application Number:
  US13/154,872
• Publication Number:
  US 20120313124A1
• Time in Patent Office: 1,099 Days
• Field of Search: 252/301.4 R, 252/301.4 F, 313/503, 313/486, 313/487, 257/98
• US Class Current: 252/301.4R
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• 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 33/502 Wavelength conversion materials

Abstract

Provided herein are phosphor compositions that include a YAG phosphor that is substituted with gallium, such as Y_aCe_bAl_cGa_dO_z, wherein a, b, c, d and z are positive numbers. Also provided are solid state light emitting devices that include a YAG phosphor that is substituted with gallium.

Claims

1. A phosphor composition comprising:

a yttrium aluminum garnet (YAG) phosphor as a primary phosphor, the YAG phosphor comprising a YAG lattice, wherein gallium is substituted into the YAG lattice, and further comprising cerium as an activator, the cerium substituting into the YAG lattice, wherein R=(moles of cerium+moles of yttrium)/(moles of gallium+moles of aluminum) and 0.5<

R<

0.6, and

wherein the phosphor composition is present as particles having an average particle diameter in a range of 2 to 25 μ

m.

2. The phosphor composition of claim 1, wherein

(moles of cerium)/(moles of cerium+moles of yttrium)=mol % Ce and 0<

mol % Ce<

10; and

(moles of gallium)/(moles of gallium+moles of aluminum)=mol % Ga and 0<

mol % Ga<

50.

3. The phosphor composition of claim 2, wherein

2<

mol % Ce<

4;

10<

mol % Ga<

30; and

0.5<

R≦

0.57.

4. The phosphor composition of claim 1, wherein the phosphor composition down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 500 nm to 570 nm.

5. The phosphor composition of claim 4, further comprising a secondary phosphor such that the secondary phosphor down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 600 nm to 660 nm.

6. The phosphor composition of claim 5, wherein the primary phosphor is about 50 to 100 weight percent of the total phosphor concentration.

7. The phosphor composition of claim 5, wherein the secondary phosphor comprises a nitride and/or oxynitride phosphor.

8. The phosphor composition of claim 7, wherein the secondary phosphor comprises (Ca_1-xSr_x)SiAlN₃:

Eu²⁺, where 0≦

x≦

1.

9. A light emitting device, comprising:

a solid state lighting source; and

a phosphor composition comprising a yttrium aluminum garnet (YAG) phosphor that has gallium substituted in the YAG phosphor,

wherein the YAG phosphor is also substituted with cerium, and

wherein R=(moles of cerium+moles of yttrium)/(moles of gallium+moles of aluminum) and 0.5<

R<

0.6.

10. The light emitting device of claim 9, wherein the solid state lighting source comprises a Group III nitride light emitting source.

11. The light emitting device of claim 9, wherein

(moles of cerium)/(moles of cerium+moles of yttrium)=mol % Ce and 0<

mol % Ce<

10; and

(moles of gallium)/(moles of gallium+moles of aluminum)=mol % Ga and 0<

mol % Ga<

50.

12. The light emitting device of claim 11, wherein

2<

mol % Ce<

4;

10<

mol % Ga<

30; and

0.5<

R≦

0.57.

13. The light emitting device of claim 9, wherein the phosphor composition down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 500 nm to 570 nm.

14. The light emitting device of claim 13, wherein the phosphor composition further comprises a secondary phosphor such that the secondary phosphor down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 600 nm to 660 nm.

15. The light emitting device of claim 14, wherein the primary phosphor is about 50 to 100 weight percent of the total phosphor concentration.

16. The light emitting device of claim 14, wherein the secondary phosphor comprises a nitride or oxynitride phosphor.

17. The light emitting device of claim 16, wherein the secondary phosphor comprises (Ca_1-xSr_x)SiAlN₃:

Eu²⁺, where 0≦

x≦

1.

18. The light emitting device of claim 9, wherein the phosphor composition further comprises a binder.

19. The light emitting device of claim 9, wherein the phosphor composition is present as particles having an average particle diameter in a range of 2 and 25 μ

m.

20. The light emitting device of claim 9, further comprising a separate secondary phosphor composition such that the phosphor composition and the separate secondary phosphor composition together down-convert radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 600 nm to 660 nm.

21. The light emitting device of claim 9, wherein the phosphor composition is present as a single crystal phosphor.

22. The light emitting device of claim 9, wherein the phosphor composition down-converts at least some of the radiation emitted by the solid state lighting source to a radiation having a peak wavelength greater than 580 nanometers.

23. The light emitting device of claim 9, wherein the phosphor composition down-converts at least some of the radiation emitted by the solid state lighting source to a radiation having a peak wavelength between 500 nanometers and 570 nanometers, and at least some of the radiation emitted by the solid state lighting source to a radiation having a peak wavelength between 600 nanometers and 660 nanometers.

24. The light emitting device of claim 9, wherein the solid state lighting source comprises a light emitting diode that emits light having a dominant wavelength in the blue color range.

25. The light emitting device of claim 24, wherein the dominant wavelength of the blue LED is between about 445 nm to 470 nm.

26. The light emitting device of claim 9, wherein the light emitting device emits a warm white light having a correlated color temperature between about 2500K and 4500K.

27. The light emitting device of claim 26, wherein the light emitting device emits a warm white light having a correlated color temperature between about 2500K and 3300K.

28. The light emitting device of claim 9, wherein the light emitting device has a CRI value of at least 90.

29. The light emitting device of claim 9, wherein the light emitted by the light emitting device has a color point that is within 7 MacAdam ellipses of the black-body locus on a 1931 CIE chromaticity diagram and has a correlated color temperature of between about 2500K and about 3300K.

30. The light emitting device of claim 9, wherein the light emitting device has a CRI R9 component of greater than 50.