Light emitting device

• US 20040095063A1
• Filed: 10/20/2003
• Published: 05/20/2004
• Est. Priority Date: 04/20/2001
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Murazaki, Yoshinori, Ichihara, Takashi
• Granted Patent: US 7,091,656 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• 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 2224/45015 being circular
• CPC Class Codes: H01L 2224/45139 Silver (Ag) as principal constituent
• 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 2224/4903 Connectors having different sizes, e.g. different diameters
• 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 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 2924/01021 Scandium [Sc]
• CPC Class Codes: H01L 2924/01066 Dysprosium [Dy]
• CPC Class Codes: H01L 2924/01067 Holmium [Ho]
• CPC Class Codes: H01L 2924/01068 Erbium [Er]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/207 Diameter ranges
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

To minimize the variability in the emitted light color and improve the unevenness of color tone, a light emitting device comprises a light emitting element and a fluorescent substance that is excited by the light emitting element, wherein the light emitting element has an emission spectrum in a region from ultraviolet to visible light of short wavelengths, and the fluorescent substance has an emission spectrum that includes two or more emission peaks with at least two peaks of the two or more peaks being in the relation of complementary colors of each other.

Claims

1. A first light emitting device comprising:

a light emitting element and a fluorescent substance that is excited by the light emitting element,

wherein the light emitting element has an emission spectrum in a region from ultraviolet to visible light of short wavelengths, and the fluorescent substance has an emission spectrum that includes two or more emission peaks with at least two peaks of the two or more peaks being in the relation of complementary colors of each other.

2. The light emitting device according to claim 1:

wherein a main emission wavelength of said light emitting element longer than 360 nm in the ultraviolet region.

3. The light emitting device according to claims 1 or 2:

wherein the emission peak of shorter wavelength of the two emission peaks which are in the relation of complementary colors of each other has smaller half width than the other emission peak.

4. The light emitting device as in any one of claims 1-3 further comprising:

an additional fluorescent substance that has another emission peak between said two emission peaks that are complementary colors of each other.

5. The light emitting device as in any one of claims 1-4:

wherein a luminous color is set by controlling the composition of the fluorescent substance to adjust the intensity ratio of the two emission peaks that are complementary colors of each other.

7. The light emitting device according to claim 1 or 6,

wherein said light emitting element has an active layer consist of a nitride semiconductor including at least In and Ga.

8. The light emitting device according to claim 1 or 6,

wherein said light emitting element has an active layer consist of a nitride semiconductor including at least Ga and Al.

9. The light emitting device as in one of claims 1, 6-8:

wherein said light emitting element has an n-type nitride semiconductor layer including an n-type contact layer, an active layer and a p-type nitride semiconductor layer including a p-type contact layer, said p-type contact layer having a light transmitting p-electrode of metal selected from the group consisting of gold and platinum group, said light transmitting p-electrode covering substantially the entire surface of said p-type contact layer,

wherein a thickness of said light transmitting p-electrode and a thickness of the n-type contact layer being set so that sheet resistance Rp Ω

/□

of said light transmitting p-electrode and sheet resistance Rn Ω

/□

of said n-type contact layer satisfy the relationship of Rp≧

Rn.

10. The light emitting device according to claim 9:

wherein the sheet resistance of said light transmitting p-electrode is 10 Ω

/□

or higher.

11. The light emitting device according to claims 9 or 10:

wherein the thickness of said light transmitting p-electrode is not more than 150 Å

.

12. The light emitting device as in one of claims 9-11:

further comprising an n-electrode disposed in the vicinity of at least one side of said semiconductor light emitting element on said n-type contact layer and a base electrode formed at a position adjacent to the side that opposes the side in the vicinity of which the n-electrode is disposed on the light transmitting p electrode, wherein extension conductors are connected to said base electrode, said extension conductors extending along the side of the light transmitting p-electrode on both sides thereof in the vicinity of which the base electrodes are located.

13. The light emitting device according to claim 12:

wherein said n-electrode is disposed at one corner of said semiconductor light emitting element so as to be close to two sides thereof, and said base electrode is located at the other corner opposite to said one corner.

14. The light emitting device according to claims 12 or 13:

wherein said extension conductors are formed in an arc shape so as to be equi-distanced from the n electrode.

15. The light emitting device as in one of claims 6-14:

wherein said fluorescent substance is Eu-activated alkali earth metal halogen-apatite fluorescent substance including at least Mn and/or Cl.

16. The light emitting device as in one of claims 6-14:

wherein said fluorescent substance is represented by (M_1-x-yEu_xM′

_y)₁₀(PO₄)₆Q₂ (M represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, M′

represents at least one kind of element selected from Mn, Fe, Cr and Sn, and Q represents at least one kind of halogen element selected from F, Cl, Br and I, where 0.0001≦

x≦

0.5 and 0.0001≦

y≦

0.5).

17. The light emitting device according to claim 16:

wherein Cl is used for Q in said formula.

18. The light emitting device as in one of claims 1-17:

further comprising a fluorescent substance selected from the group consisting of BaMg₂Al₁₆O₂₇;

Eu, BaMgAl₁₀O₁₇;

Eu, BaMgAl₁₀O₁₇;

Eu,Mn, (Sr,Ca,Ba)₅(PO₄)₃Cl;

Eu, (Sr,Ca,Ba)₁₀(PO₄)₆Cl₂, SrAl₂O₄;

Eu, Sr₄Al₁₄O₂₅;

Eu, ZnS;

Cu, Zn₂GeO₄;

Mn, BaMg₂Al₁₆O₂₇;

Eu,Mn, Y₂O₂S;

Eu, La₂O₂S;

Eu and Gd₂O₂S;

Eu.

19. The light emitting device as in one of claims 16-18:

further comprising a fluorescent substance represented by (M_1-xEu_x)₁₀(PO₄)₆Q₂ in which M represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, and Q represents at least one kind of halogen element selected from F, Cl, Br and I, where 0.0001≦

x≦

0.5 and 0.0001≦

y≦

0.5.

20. The light emitting device according to claim 19:

wherein Cl is used for Q in said formula.

6. A light emitting device comprising:

a light emitting element and a fluorescent substance that is excited by said light emitting element, wherein said light emitting element has an emission spectrum in a region from ultraviolet to visible light of short wavelengths, and the fluorescent substance is Eu-activated alkali earth metal halogen-apatite fluorescent substance that includes at least an element selected from the group consisting of Mg, Ca, Ba, Sr and Zn and an element selected from the group consisting of Mn, Fe, Cr and Sn.

21. A light emitting device comprising:

a light emitting element and a fluorescent substance that is excited by the light emitting element, wherein said light emitting element has an emission spectrum in from ultraviolet to visible light of short wavelengths, and said fluorescent substance is alkali earth metal halogen-apatite fluorescent substance that includes at least an element selected from Mg, Ca, Ba, Sr and Zn and an element selected from Mn, Fe, Cr and Sn.

22. The light emitting device according to claim 21:

wherein said fluorescent substance is alkali earth metal halogen-apatite fluorescent substance including at least Mn and/or Cl.

23. A light emitting device comprising:

a light emitting element and a fluorescent substance that is excited by the light emitting element, wherein said light emitting element has an emission spectrum in a region ranging from ultraviolet to visible light of short wavelengths, and said fluorescent substance includes a first fluorescent substance that has an emission spectrum different from that of the light emitting element and a second fluorescent substance that has an emission spectrum different from that of said first fluorescent substance.

24. The light emitting device according to claim 23:

wherein said second fluorescent substance is excited at least one of the light emitted by said light emitting element and light emitted by said first fluorescent substance.

25. The light emitting device according to claims 23 or 24:

wherein the emission spectrum of at least one of said first fluorescent substance and said second fluorescent substance has two or more peaks, of which two are in the relationship of complementary colors of each other.

26. The light emitting device as in one of claims 23-25:

wherein the peak wavelength of said light emitting element is in the relationship of complementary colors with any one of the peaks of said first fluorescent substance and said second fluorescent substance.

27. The light emitting device as in one of claims 23-25:

wherein said first fluorescent substance has an emission spectrum having a peak wavelength that is in the relationship of complementary colors with the peak wavelength of the emission spectrum of the second fluorescent substance.

28. The light emitting device as in one of claims 23-27:

wherein the main emission wavelength of said light emitting element is longer than 360 nm in the ultraviolet region.

29. The light emitting device as in one of claims 23-28:

wherein said second fluorescent substance is a cerium-activated fluorescent substance based on yttrium aluminum oxide.

30. The light emitting device as in one of claims 23-29:

wherein said first fluorescent substance is a Eu-activated alkali earth metal halogen-apatite fluorescent substance including at least an element selected from Mg, Ca, Ba, Sr and Zn and an element selected from Mn, Fe, Cr and Sn.

31. The light emitting device as in one of claims 23-30:

wherein said first fluorescent substance is a fluorescent substance selected from the group consisting of,

(1) A fluorescent substance represented by (M1_1-a-bEu_aL1_b)₁₀(PO₄)₆Q₂ in which M1 represents at least one element selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least one element selected from Mn, Fe, Cr and Sn, and Q represents at least one halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5;

(2) A fluorescent substance represented by (M1_1-aEu_a)₁₀(PO₄)₆Q₂ in which M1 represents at least one element selected from Mg, Ca, Ba, Sr and Zn, and Q represents at least one halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5;

(3) A fluorescent substance represented by (M1_1-a-bEu_aMn_b)₁₀(PO₄)₆Q₂ in which M1 represents at least one element selected from Mg, Ca, Ba, Sr and Zn, and Q represents at least one halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5;

(4) A fluorescent substance represented by (M2_1-a-cEu_aBa_c)₁₀(PO₄)₆Q₂ in which M2 represents at least one element selected from Mg, Ca, Sr and Zn, and Q represents at least one halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.10≦

c≦

0.98;

(5) A fluorescent substance represented by M1_1-aEu_aAl₂O₄ in which M1 represents at least one element selected from Mg, Ca, Ba, Sr and Zn, where 0.0001≦

a≦

0.5;

(6) A fluorescent substance represented by M1_1-a-bEu_aMn_bAl₂O₄ in which M1 represents at least one element selected from Mg, Ca, Ba, Sr and Zn, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5;

(7) A fluorescent substance represented by M3_1-a-cEu_aCa_cAl₂O₄ in which M3 represents at least one element selected from Mg, Ba, Sr and Zn, where 0.0001≦

a≦

0.5 and 0.10≦

c≦

0.98;

(8) A fluorescent substance represented by M4_1-aEu_aMgAl₁₀O₁₇ in which M4 represents at least one element selected from Ca, Ba, Sr and Zn, where 0.0001≦

a≦

0.5;

(9) A fluorescent substance represented by M4_1-aEu_aMg_1-bMn_bAl₁₀O₁₇ in which M4 represents at least one element selected from Ca, Ba, Sr and Zn where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5;

(10) A fluorescent substance represented by (M1_1-aEu_a)₄Al₁₄O₂₅ in which M1 represents at least one element selected from Mg, Ca, Ba, Sr and Zn, where 0.0001≦

a≦

0.5;

(11) A fluorescent substance represented by ZnS;

Cu;

(12) A fluorescent substance represented by (Zn,Cd) S;

Cu, Mn;

(13) A fluorescent substance represented by Re₂O₂S;

Eu in which Re represents at least one element selected from Sc, Y, La, Gd and Lu.

32. The light emitting device as in one of claims 23-30:

wherein said first fluorescent has at least a fluorescent substance represented by (M_1-a-bEu_aL1_b)₁₀(PO₄)₆Q₂ in which M1 represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least one kind of element selected from Mn, Fe, Cr and Sn, and Q represents at least one kind of halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5 and one or more fluorescent substance having composition different from said at least a fluorescent substance.

33. The light emitting device according to claims 31 or 32:

wherein said first fluorescent has at least a fluorescent substance represented by (M_1-a-bEu_aL1_b)₁₀(PO₄)₆Q₂ in which M1 represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least one kind of element selected from Mn, Fe, Cr and Sn, and Q represents at least one kind of halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5 and one or more fluorescent substance having composition different from said at least a fluorescent substance, and

wherein said second fluorescent substance is a fluorescent substance based on cerium-activated yttrium aluminum oxide.

34. The light emitting device according to claims 31 or 32:

wherein said first fluorescent substance has a fluorescent substance represented by (M_1-a-bEu_aL1_b)₁₀(PO₄)₆Q₂ and a fluorescent substance represented by (M_1-aEu_b)₁₀(PO₄)₆Q₂, in which M1 represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least one kind of element selected from Mn, Fe, Cr and Sn, and Q represents at least one kind of halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5}, and

wherein said second fluorescent substance is a fluorescent substance based on cerium-activated yttrium aluminum oxide.

35. The light emitting device according to claims 31 or 32:

wherein said first fluorescent substance has a fluorescent substance represented by (M_1-a-bEu_aL1_b)₁₀(PO₄)₆Q₂, a fluorescent substance represented by (M_1-aEu_a)₁₀(PO₄)₆Q₂ and a fluorescent substance represented by (M_1-aEu_a)₄Al₁₄O₂₅, in which M1 represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least one kind of element selected from Mn, Fe, Cr and Sn, and Q represents at least one kind of halogen element selected from F, Cl, Br and I, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5, and

wherein said second fluorescent substance is a fluorescent substance based on cerium-activated yttrium aluminum oxide.

36. The light emitting device according to claims 31 or 32:

wherein said first fluorescent substance has a fluorescent substance represented by (M_1-a-bEu_aL1_b)₁₀(PO₄)₆Q₂, a fluorescent substance represented by (M_1-aEu_a)₁₀(PO₄)₆Q₂, a fluorescent substance represented by (M_1-aEu_a)₄Al₁₄O₂₅ and a fluorescent substance represented by Re₂O₂S;

Eu in which M1 represents at least one kind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least one kind of element selected from Mn, Fe, Cr and Sn, Q represents at least one kind of halogen element selected from F, Cl, Br and I, and Re represents at least one element selected from Sc, Y, La, Gd and Lu, where 0.0001≦

a≦

0.5 and 0.0001≦

b≦

0.5, and

wherein said second fluorescent substance is a fluorescent substance based on cerium-activated yttrium aluminum oxide.

37. The light emitting device as in one of claims 23-36:

wherein the light emitting layer of said light emitting element is made of a nitride semiconductor that includes at least In and Ga.

38. The light emitting device as in one of claims 23-36:

wherein the light emitting layer of said light emitting element is made of a nitride semiconductor that includes at least Ga and Al.