Photonic crystal phosphor light conversion structures for light emitting devices

• US 9,991,427 B2
• Filed: 03/08/2010
• Issued: 06/05/2018
• Est. Priority Date: 03/08/2010
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: van de Ven, Antony P., Negley, Gerald H.
• Primary Examiner(s): Smoot, Stephen W
• Assistant Examiner(s): KIM, SUN M
• Application Number:
  US12/719,297
• Publication Number:
  US 20110215355A1
• Time in Patent Office: 3,011 Days
• Field of Search: 257E33061
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

Solid state light emitting devices include a solid state light emitting die and a photonic crystal phosphor light conversion structure. The photonic crystal phosphor light conversion structure may include a solid phosphor layer that includes dielectric nanostructures therein and may be on a light emitting surface of the solid state light emitting die. The photonic crystal phosphor light conversion structure may be attached to the light emitting surface of the solid state light emitting die via an adhesive layer. The photonic crystal phosphor light conversion structure may also be directly on a light emitting surface of the solid state light emitting die. Related methods are also disclosed.

Claims

1. A photonic crystal phosphor comprising a single crystal of phosphor having a first face and a second face opposite the first face, wherein the single crystal of phosphor comprises dielectric nanostructures therein, and wherein the dielectric nanostructures extend from the first face of the single crystal of phosphor toward the second face of the single crystal of phosphor by a distance between 40% and 95% of a thickness of the single crystal of phosphor;

wherein each dielectric nanostructure of a first portion of the dielectric nanostructures has a width that is less than a width of each dielectric nanostructure of a second portion of the dielectric nanostructures, wherein each dielectric nanostructure of the first portion of the dielectric nanostructures has a depth that is greater than a depth of each dielectric nanostructure of the second portion of the dielectric nanostructures, and wherein the second portion of the dielectric nanostructures are dispersed among the first portion of the dielectric nanostructures.

2. A solid state light emitting device comprising:

a primary solid state light emitting die that is configured to emit light upon energization thereof; and

a light conversion structure comprising the photonic crystal phosphor of claim 1 on a light emitting surface of the primary solid state light emitting die.

3. The solid state light emitting device of claim 2, further comprising an adhesive layer that attaches the light conversion structure to the light emitting surface.

4. The solid state light emitting device of claim 3, wherein the adhesive layer comprises silicone polymer.

5. The solid state light emitting device of claim 2, wherein the light conversion structure is sized to fit the light emitting surface of the primary solid state light emitting die.

6. The solid state light emitting device of claim 2, wherein the single crystal of phosphor comprises cerium.

7. The solid state light emitting device of claim 6, wherein the single crystal of phosphor comprises cerium at a concentration in a range of about 0.1 to about 20 weight percent.

8. The solid state light emitting device of claim 6, wherein the single crystal of phosphor comprises Y₃Al₅O₁₂ doped with Ce³⁺ Ce:

YAG).

9. The solid state light emitting device of claim 6, wherein single crystal of phosphor comprises Ca_xSr_yMg_1-x-yAlSiN₃ doped with cerium or strontium thio-gallate doped with cerium.

10. The solid state light emitting device of claim 2, wherein the single crystal of phosphor comprises europium.

11. The solid state light emitting device of claim 10, wherein the single crystal of phosphor comprises europium at a concentration in a range of about 0.5 to about 20 weight percent.

12. The solid state light emitting device of claim 10, wherein the single crystal of phosphor comprises Sr_2-xBa_xSiO₄ doped with Eu²⁺ (BOSE).

13. The solid state light emitting device of claim 10, wherein the single crystal of phosphor comprises a europium doped material, wherein the material is selected from the group consisting of Ca_xSr_1-xAlSiN₃, strontium thio-gallate, alpha-SiAlON, silicon garnet, Y₂O₂S and La₂O₂S.

14. The solid state light emitting device of claim 2, wherein a surface of the light conversion structure is texturized, roughened, etched and/or featured.

15. The solid state light emitting device of claim 2, wherein the light conversion structure is directly on the light emitting surface of the primary solid state light emitting die.

16. The solid state light emitting device of claim 2, wherein the light conversion structure acts as a substrate for the primary solid state light emitting die.

17. The solid state light emitting device of claim 2, wherein the single crystal of phosphor has a thickness in a range of about 1 μ

m to about 200 μ

m.

18. The solid state light emitting device of claim 2, wherein the single crystal of phosphor is spatially separated from the primary solid state light emitting die.

19. The solid state light emitting device of claim 2, further comprising one or more additional solid state light emitting die configured to emit light upon energization thereof.

20. The solid state light emitting device of claim 19, wherein the first portion of the dielectric nanostructures are configured to interact with a first light emitted from the primary solid state light emitting die and the second portion of the dielectric nanostructures are configured to interact with a second light emitted from at least one of the one or more additional solid state light emitting die, wherein the first light has a different wavelength than the second light, and wherein the first light interacts with the first portion of dielectric nanostructures differently than the second light, and wherein the second light interacts with the second portion of dielectric nanostructures differently than the first light.

21. The solid state light emitting device of claim 2, wherein the dielectric nanostructures comprise holes that traverse the single crystal of phosphor in a direction parallel to the light emitting surface of the primary solid state light emitting die.

22. The photonic crystal phosphor of claim 1, wherein the dielectric nanostructures are formed in a periodic array, wherein a period of the periodic array is configured to be half a wavelength of electromagnetic waves propagated through the periodic array.

23. The photonic crystal phosphor of claim 1, wherein the dielectric nanostructures are spaced between 200 nm and 500 nm apart.

24. The photonic crystal phosphor of claim 1, wherein the dielectric nanostructures have a width between 50 nm and 200 nm.

25. The photonic crystal phosphor of claim 1, wherein the first portion of the dielectric nanostructures are configured to interact with a first solid state light emitting die and the second portion of the dielectric nanostructures are configured to interact with a second solid state light emitting die, wherein dielectric nanostructures of the second portion have a size and/or shape different than dielectric nanostructures of the first portion and wherein the second portion of the dielectric nanostructures are dispersed among the first portion of the dielectric nanostructures.

26. A solid state light emitting device comprising:

a primary solid state light emitting die that is configured to emit light upon energization thereof; and

a light conversion structure comprising the photonic crystal phosphor of claim 1 on a light emitting surface of the primary solid state light emitting die, wherein the dielectric nanostructures comprise holes that are parallel to the light emitting surface of the primary solid state light emitting die, and wherein each hole is configured to direct light through the solid phosphor layer in a direction parallel to the light emitting surface of the primary solid state light emitting die.