Phosphor converted light emitting diode

• US 6,417,019 B1
• Filed: 04/04/2001
• Issued: 07/09/2002
• Est. Priority Date: 04/04/2001
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Mueller-Mach, Regina B., Mueller, Gerd O.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Simkovic, Viktor
• Application Number:
  US09/827,382
• Time in Patent Office: 461 Days
• Field of Search: 438/29, 438/38, 438/49, 438/69, 438/70, 438/71, 438/72, 372/11, 372/32, 372/49, 359/248, 359/273, 359/294, 359/581, 257/98, 257/99, 257/100, 257/788, 257/789, 257/790, 257/793
• US Class Current: 438/29
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/06102 the bonding areas being at different heights
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/1703 Bump connectors having different sizes, e.g. different diameters, heights or widths
• 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

A method of fabricating a light emitting device includes providing a light emitting diode that emits primary light, and locating proximate to the light emitting diode a (Sr_{1−u−v−x}Mg_uCa_vBa_x)(Ga_2−y−zAl_yIn_zS₄):Eu²⁺ phosphor material capable of absorbing at least a portion of the primary light and emitting secondary light having a wavelength longer than a wavelength of the primary light. The composition of the phosphor material can be selected to determine the wavelengths of the secondary light. In one embodiment, the light emitting device includes the phosphor material dispersed as phosphor particles in another material disposed around the light emitting diode. In another embodiment, the light emitting device includes the phosphor material deposited as a phosphor film on at least one surface of the light emitting diode.

Claims

1. A light emitting device comprising:

a light emitting diode that emits primary light; and

a (Sr<sub>1−

u−

v−

x</sub>Mg_uCa_vBa_x)(Ga<sub>2−

y−

z</sub>Al_yIn_zS₄);

Eu²⁺ phosphor material capable of absorbing at least a portion of said primary light and emitting secondary light having a wavelength longer than a wavelength of said primary light,

wherein 0≦

u≦

1, 0≦

v≦

1, 0≦

x≦

1, 0≦

(u+v+x)≦

1, 0≦

y≦

2, 0≦

z≦

2, and 0≦

y+z≦

2.

2. The light emitting device of claim 1, wherein said light emitting diode comprises an Al_rIn_sGa_tN material with 0≦

r≦

1, 0≦

s≦

1, 0≦

t≦

1, and r+s+t=1.

3. The light emitting device of claim 1, wherein said light emitting diode is a laser diode.

4. The light emitting device of claim 1, wherein said primary light has a wavelength between about 380 nanometers and about 500 nanometers.

5. The light emitting device of claim 1, wherein said secondary light has a wavelength between about 490 nanometers and about 610 nanometers.

6. The light emitting device of claim 1, wherein said phosphor material absorbs a sufficient portion of said primary light that a total power of unabsorbed primary light is less than about 5% of a total power of all emitted secondary light.

7. The light emitting device of claim 1, wherein said phosphor material is dispersed as phosphor particles in another material disposed around at least a portion of said light emitting diode.

8. The light emitting device of claim 7, wherein a layer of said phosphor particles and said other material is disposed on at least one surface of said light emitting diode.

9. The light emitting device of claim 7, wherein said other material is a material selected from the group consisting of epoxies, acrylic polymers, polycarbonates, silicone polymers, optical glasses, and chalcogenide glasses.

10. The light emitting device of claim 7, wherein said other material has a refractive index greater than about 1.5 at a wavelength of said primary light.

11. The light emitting device of claim 7, wherein said other material has a refractive index greater than about 2.1 at a wavelength of said primary light.

12. The light emitting device of claim 1, wherein said phosphor material is deposited as an optically homogenous phosphor film on at least one surface of said light emitting diode.

13. The light emitting device of claim 12, wherein a thickness of said phosphor film is about 2 microns to about 20 microns.

14. The light emitting device of claim 12, wherein said light emitting diode includes a substrate layer, and said phosphor film is deposited on at least one surface of said substrate layer.

31. The light emitting device of claim 1, wherein said phosphor material is positioned directly on at least a portion of said light emitting diode.

15. A method of fabricating a light emitting device, the method comprising:

providing a light emitting diode that emits primary light; and

positioning a (Sr<sub>1−

u−

v−

x</sub>Mg_uCa_vBa_x)(Ga<sub>2−

y−

z</sub>Al_yIn_zS₄);

Eu²⁺ phosphor material relative to said light emitting diode such that said phosphor material can absorb at least a portion of said primary light and emit secondary light having a wavelength longer than a wavelength of said primary light,

wherein 0≦

u≦

1, 0≦

v≦

1, 0≦

x≦

1, 0≦

(u+v+x)≦

1, 0≦

y≦

2, 0≦

z≦

2, and 0≦

y+z≦

2.

16. The method of claim 15, wherein said light emitting diode comprises an Al_rIn_sGa_tN material with 0≦

r≦

1,0≦

s ≦

1,0≦

t≦

1, and r+s+t=1.

17. The method of claim 15, wherein said light emitting diode is a laser diode.

18. The method of claim 15, wherein said primary light has a wavelength between about 380 nanometers and about 500 nanometers.

19. The method of claim 15, wherein said secondary light has a wavelength between about 490 nanometers and about 610 nanometers.

20. The method of claim 15, further comprising selecting values of u, v, x, y, and z to determine a wavelength of said secondary light.

21. The method of claim 15, further comprising dispersing said phosphor material as phosphor particles in another material, and disposing said other material around at least a portion of said light emitting diode.

22. The method of claim 21, wherein said other material is a material selected from the group consisting of epoxies, acrylic polymers, polycarbonates, silicone polymers, optical glasses, and chalcogenide glasses.

23. The method of claim 21, wherein said other material has a refractive index greater than about 1.5 at a wavelength of said primary light.

24. The method of claim 21, wherein said other material has a refractive index greater than about 1.8 at a wavelength of said primary light.

25. The method of claim 21, further comprising selecting a concentration of said phosphor particles in said other material such that said phosphor particles absorb a sufficient portion of said primary light that a total power of unabsorbed primary light is less than about 5% of a total power of all emitted secondary light.

26. The method of claim 21, further comprising selecting a concentration of said phosphor particles in said other material to adjust a chromaticity of a mixture of said primary light and said secondary light.

27. The method of claim 15, further comprising depositing said phosphor material as an optically homogenous phosphor film on at least one surface of said light emitting diode.

28. The method of claim 27, further comprising selecting a thickness of said phosphor film such that said phosphor film absorbs a sufficient portion of said primary light that a total power of unabsorbed primary light is less than about 5% of a total power of all emitted secondary light.

29. The method of claim 27, further comprising selecting a thickness of said phosphor film to adjust a chromaticity of a mixture of said primary light and said secondary light.

30. The method of claim 27, further comprising annealing said film at a temperature of about 500°

C. to about 800°

C.

32. A light emitting device comprising:

a light emitting diode that emits blue light; and

a (Sr_1-u-v-xMg_uCa_vBax)(Ga_2-y-zAl_yIn_zS₄);

Eu ²⁺ phosphor material capable of absorbing at least a portion of said blue light and emitting secondary light having a wavelength longer than a wavelength of said blue light,

wherein 0≦

u≦

1,0≦

v≦

1,0≦

x≦

1,0≦

(u+v+x)≦

1,0≦

y≦

2,0≦

z≦

2, and 0≦

y+z≦

2.

33. The light emitting device of claim 32, wherein said phosphor material is dispersed as phosphor particles in another material disposed around at least a portion of said light emitting diode.

34. The light emitting device of claim 32, wherein said phosphor material is deposited as an optically homogenous phosphor film on at least one surface of said light emittind diode.