Cerium and europium doped single crystal phosphors

• US 8,119,028 B2
• Filed: 10/14/2008
• Issued: 02/21/2012
• Est. Priority Date: 11/14/2007
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Le Toquin, Ronan P.
• Primary Examiner(s): Koslow, Carol M
• Application Number:
  US12/250,828
• Publication Number:
  US 20090121615A1
• Time in Patent Office: 1,225 Days
• Field of Search: 252/301.4 F
• US Class Current: 252/301.4F
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77218 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77928 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 2924/00012 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 2924/181 Encapsulation
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

Compounds of Formula I, which include both cerium and europium, may be useful as phosphors in solid state light emitting devices. Light emitting devices including such phosphors may emit warm white light.

Claims

1. A single crystal phosphor preform comprising a single crystal of a material having a compound of Formula I:

A_aB_bC_cD_dE_e 

 

(I)

wherein A comprises one or more elements selected from the group consisting of Ca, Sr, Ba, Mg, Y, Hf, the lanthanide elements and the other alkaline earth metals;

B comprises Eu and Ce;

C comprises one or more tetrahedrally-coordinated trivalent elements;

D comprises one or more tetrahedrally-coordinated tetravalent elements;

E comprises one or more elements selected from the group consisting of N, O, F, C, S, Cl, Br and I, wherein a+b=1 and c+d=2;

and the compound has a CaAlSiN₃-type crystal structure;

wherein the single crystal phosphor preform comprises a single crystal that is configured to be attached to a light emitting diode.

2. The single crystal phosphor preform according to claim 1, wherein a, b, c, d and e satisfy the following requirements:

a is in a range of 0.7 to 0.99;

b is in a range of 0.01 to 0.3;

c is in a range of 0.5 to 1.5;

d is in a range of 0.5 to 1.5;

e is in a range of 2.5 to 3.5.

3. The single crystal phosphor preform according to claim 1, wherein b is in a range of 0.05 to 0.2.

4. The single crystal phosphor preform according to claim 1, wherein A comprises one or more of elements selected from the group consisting of Mg, Ba, Sr and Ca.

5. The single crystal phosphor preform according to claim 4, wherein A comprises Ca.

6. The single crystal phosphor preform according to claim 1, wherein C comprises one or more elements selected from the group consisting of Al, B, Ga, P, In, Sc, Y, Gd, and Lu.

7. The single crystal phosphor preform according to claim 6, wherein C comprises Al.

8. The single crystal phosphor preform according to claim 1, wherein D comprises one or more elements selected from the group consisting of Si, Ge, Sn, Ti, Zr and Hf.

9. The single crystal phosphor preform according to claim 8, wherein D comprises Si.

10. The single crystal phosphor preform according to claim 1, wherein E comprises N, C, S, Cl, Br, I and/or F.

11. The single crystal phosphor preform according to claim 10, wherein E comprises N.

12. The single crystal phosphor preform according to claim 1, wherein A comprises Sr and Ca, wherein χ

(Sr)+χ

(Ca)=1.

13. The single crystal phosphor preform according to claim 1, wherein C comprises Al and D comprises Si, wherein c+d=2.

14. The single crystal phosphor preform according to claim 1, wherein E comprises O and N, and χ

(O)+χ

(N)=3.

15. The single crystal phosphor preform according to claim 1, wherein cerium and europium are together present in the compound at concentration in a range of about 0.1% to about 20% by weight.

16. The single crystal phosphor preform according to claim 1, which has a maximum emission wavelength in a range of 500 to 700 nm.

17. The single crystal phosphor preform according to claim 16, wherein the maximum emission wavelength occurs when the phosphor is irradiated with radiation in a range of about 380 nm to about 480 nm.

18. The single crystal phosphor preform according to claim 17, wherein the full width at half maximum is less than about 200 nm.