Light emitting device having a divalent-europium-activated alkaline earth metal orthosilicate phosphor

• US 7,157,746 B2
• Filed: 09/30/2004
• Issued: 01/02/2007
• Est. Priority Date: 12/28/2000
• Status: Expired due to Term

• Current Assignee: Leuchtstoffwerk Breitungen GmbH, Litec Gbr, Toyoda Gosei Company Limited (Toyota Motor Corporation), Tridonic Optoelectronics GmbH
• Original Assignee: Leuchtstoffwerk Breitungen GmbH, Litec Gbr, Toyoda Gosei Company Limited (Toyota Motor Corporation), Tridonic Optoelectronics GmbH
• Inventors: Starick, Detlef, Roth, Gundula, Tews, Walter, Tasch, Stefan, Pachler, Peter, Ota, Koichi, Hirano, Atsuo, Kempfert, Wolfgang, Ota, Akihito
• Primary Examiner(s): Dickey; Thomas L.
• Application Number:
  US10/952,937
• Publication Number:
  US 20050077532A1
• Time in Patent Office: 824 Days
• Field of Search: 257 13- 18, 257/20, 257/22, 257 76- 82, 257/84, 257 94- 96, 257 98-103, 313456-473, 313/505, 372 10- 14, 372 66- 75
• US Class Current: 257/100
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/77344 Aluminosilicates
• CPC Class Codes: C09K 11/774 Borates
• CPC Class Codes: C09K 11/7795 Phosphates
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/45139 Silver (Ag) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/00011 : Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/181 : Encapsulation
• 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 33/06 : within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/32 : containing nitrogen
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: H01L 33/507 : the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: Y02B 20/00 : Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

The light emitting device has a light emitting diode which is made of a nitride semiconductor and a phosphor which absorbs a part of lights emitted from the light emitting diode and emits different lights with wavelengths other than those of the absorbed lights. The phosphor is made of alkaline earth metal silicate fluorescent material activated with europium.

Claims

1. A light emitting device, comprising:

a light emitting element comprising a nitride semiconductor; and

a phosphor which can absorb a part of light emitted from said light emitting element and can emit light of a wavelength different from that of said absorbed light,

wherein the phosphor comprises at least one of divalent-europium-activated alkaline earth metal orthosilicates represented by a formula;

(Sr_(1-x-y)Ba_xCa_y)₂(Si<sub>(1-α

-β

-γ

-δ

)</sub>P_α

Al_β

B_γ

Ge_δ

)O₄;

Eu²⁺

 

where 0<

x≦

0.8, 0≦

y<

0.8, 0<

x+y<

1, 0≦

α

, β

, γ

<

0.25, 0≦

δ

<

0.5, 0≦

α

+β

+γ

+δ

<

1.

2. The light emitting device according to claim 1, further comprising:

a transparent optical guide plate that comprises an optical connection face that is optically connected with the light emitting element, and a light-emitting face that light emitted from the light emitting element passes through;

a casing that covers a face of the optical guide plate other than the light-emitting face, the casing being provided with a reflection member inside thereof; and

a transparent film that is provided on the light-emitting face,

wherein the transparent film comprises the phosphor.

3. The light emitting device according to claim 1, further comprising:

an insulating substrate that is provided with a wiring pattern formed thereon, the light emitting element being mounted on the insulating substrate and wire-bonded to the wiring pattern;

a cup that is mounted on the insulating substrate while surrounding the light emitting element; and

a transparent sealing member that is filled inside the cup to cover the light emitting element,

wherein the transparent sealing member comprises the phosphor.

4. The light emitting device according to claim 1, further comprising:

a lead frame that is provided with a cup;

an overvoltage protection element that is mounted on the bottom of the cup and is provided with electrodes formed thereon, the light emitting element being flip-chip mounted on the overvoltage protection element while being electrically connected to the light emitting element through the electrodes thereof; and

a transparent sealing member that is filled inside the cup to cover the light emitting element,

wherein the transparent sealing member comprises the phosphor.

5. The light emitting device according to claim 1, further comprising:

a lead frame that is provided with a cup, the light emitting element being mounted on the bottom of the cup;

a transparent sealing member that is provided to seal the inside of the cup and the periphery of the lead frame, and

a transparent phosphor cover that is formed on the outer surface of the transparent sealing member,

wherein the transparent phosphor cover comprises the phosphor.

6. A light emitting device, comprising:

a light emitting element comprising a nitride semiconductor, said light emitting element generating blue light; and

a phosphor which can absorb a part of said blue light emitted from the light emitting element and can emit yellow light of a wavelength different from that of said absorbed light,

wherein a half-value width of a wavelength emitted from said light emitting element is not more than 40 nm,

a wavelength emitted from said phosphor has a half bandwidth up to 110 nm,

said light emitting element comprises a double hetero structure comprising a light emitting layer sandwiched between a p-type cladding layer and an n-type cladding layer, and

the p-type cladding layer comprises a superlattice structure.

7. The light emitting device according to claim 6, wherein said phosphor is mixed into a covering member which covers said light emitting element.

8. The light emitting device according to claim 7, wherein said covering member comprises a silicone resin.

9. The light emitting device according to claim 7, wherein said covering member comprises a low-melting glass.

10. The light emitting device according to claim 6, wherein:

said phosphor is mixed into a covering member which covers said light emitting element; and

a scattering agent is mixed into the covering member.

11. The light emitting device according to claim 6, wherein said light emitting element comprises a light emitting layer containing indium.

12. The light emitting device according to claim 6, wherein the phosphor comprises at least one of divalent-europium-activated alkaline earth metal orthosilicates represented by a formula:

(Sr_(1-x-y)Ba_xCa_y)₂(Si<sub>(1-α

-β

-γ

-δ

)</sub>P_α

Al_β

B_γ

Ge_δ

)O₄;

Eu²⁺

 

where 0<

x≦

0.8, 0≦

y<

0.8, 0<

x+y<

1, 0≦

α

, β

, γ

<

0.25, 0≦

δ

<

0.5, 0≦

α

+β

+γ

+δ

<

1.

13. A light emitting device, comprising:

a light emitting element comprising a nitride semiconductor, said light emitting element generating a blue light; and

a phosphor which can absorb a part of said blue light emitted from the light emitting element and can emit yellow light of a wavelength different from that of said absorbed light,

wherein a half-value width of a wavelength emitted from said light emitting element is not more than 40 nm,

a wavelength emitted from said phosphor has a half bandwidth up to 110 nm,

said light emitting element comprises a double heterostructure comprising a light emitting layer sandwiched between a p-type cladding layer and an n-type cladding layer, and

the n-type cladding layer comprises a superlattice structure.

14. The ligth emitting device according to claim 13, wherein:

said phosphor is mixed into a covering member which covers said light emitting element.

15. The light emitting device according to claim 14, wherein:

said covering member comprises a silicone resin.

16. The light emitting device according to claim 14, wherein:

said covering member comprises a low-melting glass.

17. The light emitting device according to claim 13, wherein:

said phosphor is mixed into a covering member which covers said light emitting element and,

a scattering agent is mixed into the covering member.

18. The light emitting device according to claim 13, wherein:

said light emitting element comprises a light emitting layer containing indium.

19. The light emitting device according to claim 13, wherein:

the phosphor comprises at least one of divalent-europium-activated alkaline earth metal orthosilicates represented by a formula;

(Sr_(1-x-y)Ba_xCa_y)₂(Si<sub>(1-α

-β

-γ

-δ

)</sub>P_α

Al_β

B_γ

Ge_δ

)O₄;

Eu²⁺

 

where 0<

x≦

0.8, 0≦

y<

0.8, 0<

x+y<

1, 0≦

α

, β

, γ

<

0.25, 0≦

δ

<

0.5, 0≦

α

+β

+γ

+δ

<

1.

20. A light emitting device, comprising:

a light emitting element comprising a nitride semiconductor, said light emitting element generating a blue light; and

a phosphor which can absorb a part of said blue light emitted from the light emitting element and can emit yellow light of a wavelength different from that of said absorbed light,

wherein a half-value width of a wavelength emitted from said light emitting element is not more than 40 nm,

a wavelength emitted from said phosphor has a half bandwidth up to 100 nm,

said light emitting element comprises a double hetero structure comprising a light emitting layer sandwiched between a p-type cladding layer and an n-type cladding layer,

the n-type cladding layer comprises a superlattice structure, and

the p-type cladding layer comprises a superlattice structure.

21. The light emitting device according to claim 20, wherein:

said phosphor is mixed into a covering member which covers said light emitting element.

22. The light emitting device acccording to claim 21, wherein:

said covering member comprises a silicone resin.

23. The light emitting device according to claim 21, wherein:

said covering member comprises a low-melting glass.

24. The light emitting device according to claim 20, wherein:

said phosphor is mixed into a covering member which covers said light emitting element, and

a scattering agent is mixed into the covering member.

25. The light emitting device according to claim 20, wherein:

said light emitting element comprises a light emitting layer containing indium.

26. The light emitting device according to claim 20, wherein:

the phosphor comprises at least one of divalent-europium-activated alkaline earth metal orthosilicates represented by a formula;

(Sr_(1-x-y)Ba_xCa_y)₂(Si<sub>(1-α

-β

-γ

-δ

)</sub>P_α

Al_β

B_γ

Ge_δ

)O₄;

Eu²⁺

 

where 0<

x≦

0.8, 0≦

y<

0.8, 0<

x+y<

1, 0≦

α

, β

, γ

<

0.25, 0≦

δ

<

0.5, 0≦

α

+β

+γ

+δ

<

1.

27. A light emitting device, comprising:

a light emitting element comprising a nitride semiconductor, said light emitting element generating blue light; and

a phosphor which can absorb a part of said blue light emitted from the light emitting element and can emit yellow light of a wavelength different from that of said absorbed light, wherein a half-value width of a wavelength emitted from said light emitting element is not more than 40 nm,

wherein the phosphor comprises a divalent-europium-activated alkaline earth metal orthosilicate, and

the phosphor comprises at least one of divalent-europium-activated alkaline earth metal orthosilicates represented by a formula;

(Sr_(1-x-y)Ba_xCa_y)₂(Si<sub>(1-α

-β

-γ

-δ

)</sub>P_α

Al_β

B_γ

Ge_δ

)O₄;

Eu²⁺

 

where 0<

x≦

0.8, 0≦

y<

0.8, 0<

x+y<

1, 0≦

α

, β

, γ

<

0.25, 0≦

δ

<

0.5, 0≦

α

+β

+γ

+δ

<

1.