Phosphor, semiconductor light emitting device, and fabrication method thereof

• US 20050051790A1
• Filed: 06/04/2004
• Published: 03/10/2005
• Est. Priority Date: 06/05/2003
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ueda, Tetsuzo
• Granted Patent: US 7,268,370 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: C09K 11/595 with zinc or cadmium
• CPC Class Codes: C09K 11/646 Silicates
• CPC Class Codes: C09K 11/70 containing phosphorus
• CPC Class Codes: C09K 11/7709 Phosphates
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/77742 Silicates
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 33/0066 with a substrate not being a III-V compound
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A phosphor that emits white light due to excitation by a light emitting diode capable of emitting blue or ultraviolet light includes: a substrate that allows transmission of visible light; and a semiconductor layer formed on the substrate.

Claims

1. A phosphor that emits white light due to excitation by a light emitting diode capable of emitting blue or ultraviolet light, the phosphor characterized by comprising:

a substrate that allows transmission of visible light; and

a semiconductor layer formed on the substrate.

2. The phosphor according to claim 1,

wherein the phosphor further comprises a phosphor layer made of a phosphor material formed on a surface of the substrate opposite to a surface thereof on which the semiconductor layer is formed, or on a surface of the semiconductor layer opposite to a surface thereof on which the substrate is formed.

3. The phosphor according to claim 2,

wherein the phosphor layer comprises at least a first phosphor layer and a second phosphor layer, and

wherein the first phosphor layer and the second phosphor layer emit lights having different center wavelengths due to excitation by the light emitting diode.

4. The phosphor according to claim 3,

wherein the first phosphor layer is formed by Zn₂SiO₄ to which Mn is added, BaAl₁₂O₁₉ to which Mn is added, CeMgAl₁₁ to which Tb is added, BaMgAl₁₀O₁₇ to which Eu²⁺ and Mn²⁺ are added, or Y₂SiO₅ to which Ce³⁺ and Tb³⁺ are added, and

wherein the second phosphor layer is formed by BaMgAl₁₄O₂₃ to which Eu is added, YP_0.85V_0.15O₄, BaMg₂Al₁₄ to which Eu is added, (Sr, Ca)₁₀(PO₄)₆Cl₂ to which Eu²⁺ is added, or BaMgAl₁₀O₁₇ to which Eu²⁺ is added.

5. The phosphor according to claim 2,

wherein the phosphor layer is formed by a single layer consisting of a YAG phosphor, or a plurality of layers including at least the YAG phosphor.

6. The phosphor according to claim 1,

wherein the semiconductor layer emits red light due to excitation by the light emitting diode.

7. The phosphor according to claim 6,

wherein the semiconductor layer is made of InGaAlP.

8. The phosphor according to claim 1,

wherein the semiconductor layer comprises at least a first semiconductor layer and a second semiconductor layer,

wherein the first semiconductor layer emits red light due to excitation by the light emitting diode, and

wherein the second semiconductor layer emits green light due to excitation by the light emitting diode.

9. The phosphor according to claim 8,

wherein the first semiconductor layer is made of InGaAlP, and

wherein the second semiconductor layer is made of ZnMgSSe.

10. The phosphor according to claim 1,

wherein the substrate that allows transmission of visible light is a quartz substrate, a glass substrate or a sapphire substrate.

12. The semiconductor light emitting device according to claim 11,

wherein the phosphor further comprises a phosphor layer made of a phosphor material formed on a surface of the substrate opposite to a surface thereof on which the semiconductor layer is formed, or on a surface of the semiconductor layer opposite to a surface thereof on which the substrate is formed.

11. A semiconductor light emitting device that emits white light, the device characterized by comprising:

a light emitting diode chip capable of emitting blue or ultraviolet light; and

a phosphor comprising;

a substrate that allows transmission of visible light, the substrate being located at a position which enables transmission of light emitted from the light emitting diode chip; and

a semiconductor layer formed on the substrate,

wherein the light emitting diode chip and the phosphor are mounted in a single package.

13. A semiconductor light emitting device that emits white light, the device characterized by comprising:

a diode that is formed on a substrate, has an active layer made of InGaAlN, and is capable of emitting blue or ultraviolet light;

a transparent electrode that is formed on the diode, and allows transmission of light emitted from the diode;

a semiconductor layer formed on the transparent electrode; and

a phosphor layer made of a phosphor material formed on the semiconductor layer.

14. The semiconductor light emitting device according to claim 13,

wherein the transparent electrode is made of an ITO material.

15. A semiconductor light emitting device that emits white light, the device characterized by comprising:

a diode that is formed on a substrate, has an active layer made of InGaAlN, and is capable of emitting blue or ultraviolet light;

a transparent electrode that is formed on the diode, and allows transmission of light emitted from the diode; and

a plurality of semiconductor layers formed over the transparent electrode and having different compositions.

16. The semiconductor light emitting device according to claim 15,

wherein the transparent electrode is made of an ITO material.

17. A semiconductor light emitting device that emits white light, the device characterized by comprising:

a diode that has an active layer made of InGaAlN, and is capable of emitting blue or ultraviolet light;

a transparent electrode that is formed on the diode, and allows transmission of light emitted from the diode;

a semiconductor layer formed on the transparent electrode;

a substrate that is formed on the semiconductor layer, and allows transmission of light emitted from the diode and the semiconductor layer; and

a phosphor layer made of a phosphor material formed on the substrate.

18. The semiconductor light emitting device according to claim 17,

wherein the device further comprises an electrode formed on a surface of the diode opposite to a surface thereof on which the transparent electrode is formed, and

wherein the electrode is made of Al, Ag, Rh, Pt, or an alloy or multilayer metal film including any of these metals.

19. A semiconductor light emitting device that emits white light, the device comprising:

a diode that has an active layer made of InGaAlN, and is capable of emitting blue or ultraviolet light;

a transparent electrode that is formed on the diode, and allows transmission of light emitted from the diode;

a plurality of semiconductor layers formed over the transparent electrode and having different compositions; and

a substrate that is formed over the plurality of semiconductor layers, and allows transmission of light emitted from the diode and the plurality of semiconductor layers.

20. The semiconductor light emitting device according to claim 19,

wherein the device further comprises an electrode formed on a surface of the diode opposite to a surface thereof on which the transparent electrode is formed, and

wherein the electrode is made of Al, Ag, Rh, Pt, or an alloy or multilayer metal film including any of these metals.

21. A method for fabricating a phosphor that emits white light due to excitation by a light emitting diode capable of emitting blue or ultraviolet light, the method characterized by comprising the steps of:

forming a semiconductor layer on a first substrate made of a single crystal, and then bonding a second substrate that allows transmission of visible light onto a surface of the semiconductor layer opposite to a surface thereof on which the first substrate is formed;

separating the first substrate from the semiconductor layer; and

forming a phosphor layer made of a phosphor material, on a surface of the second substrate opposite to a surface thereof on which the semiconductor layer is formed, or on a surface of the semiconductor layer opposite to a surface thereof on which the second substrate is formed.

22. The method for fabricating a phosphor according to claim 21,

wherein the step of forming the phosphor layer comprises the step of forming at least a first phosphor layer and a second phosphor layer, and

wherein the first phosphor layer and the second phosphor layer emit lights having different center wavelengths due to excitation by the light emitting diode.

23. A method for fabricating a phosphor that emits white light due to excitation by a light emitting diode capable of emitting blue or ultraviolet light, the method characterized by comprising the steps of:

forming a plurality of semiconductor layers over a first substrate made of a single crystal;

bonding a second substrate that allows transmission of visible light onto a surface of the plurality of semiconductor layers opposite to a surface thereof on which the first substrate is formed; and

separating the first substrate from the plurality of semiconductor layers.

24. The method for fabricating a phosphor according to claim 23,

wherein the step of forming the plurality of semiconductor layers comprises the step of forming at least a first semiconductor layer and a second semiconductor layer which emit red light and green light, respectively, due to excitation by the light emitting diode.

25. The method for fabricating a phosphor according to claim 24,

wherein the first substrate is made of GaAs,

wherein the first semiconductor layer is made of InGaAlP, and

wherein the second semiconductor layer is made of ZnMgSSe.

26. The method for fabricating a phosphor according to claim 25,

wherein at least one of the first semiconductor layer and the second semiconductor layer has a composition that can be lattice-matched to the first substrate.

27. A method for fabricating a semiconductor light emitting device that emits white light, the method characterized by comprising the steps of:

forming, on a first substrate, a diode that has an active layer made of InGaAlN and is capable of emitting blue or ultraviolet light;

forming, on a surface of the diode opposite to a surface thereof on which the first substrate is formed, a transparent electrode that allows transmission of light emitted from the diode;

forming a semiconductor layer on a second substrate made of a single crystal;

bonding together a surface of the transparent electrode opposite to a surface thereof on which the diode is formed, and a surface of the semiconductor layer opposite to a surface thereof on which the second substrate is formed;

separating the second substrate from the semiconductor layer; and

forming a phosphor layer made of a phosphor material, on a surface of the semiconductor layer opposite to a surface thereof on which the transparent electrode exists.

28. The method for fabricating a semiconductor light emitting device according to claim 27,

wherein the phosphor layer is formed by a single layer consisting of a YAG phosphor, or a plurality of layers including at least the YAG phosphor.

30. The method for fabricating a semiconductor light emitting device according to claim 27,

wherein the first substrate is made of sapphire, SiC, MgO, LiGaO₂, LiAlO₂, or a mixed crystal of LiGaO₂ and LiAlO₂.

29. A method for fabricating a semiconductor light emitting device that emits white light, the method characterized by comprising the steps of:

forming, on a first substrate, a diode that has an active layer made of InGaAlN and is capable of emitting blue or ultraviolet light;

forming, on a surface of the diode opposite to a surface thereof on which the first substrate is formed, a transparent electrode that allows transmission of light emitted from the diode;

forming a plurality of semiconductor layers on a second substrate made of a single crystal;

bonding together a surface of the transparent electrode opposite to a surface thereof on which the diode is formed, and a surface of the plurality of semiconductor layers opposite to a surface thereof on which the second substrate is formed; and

separating the second substrate from the plurality of semiconductor layers.

31. A method for fabricating a semiconductor light emitting device that emits white light, the method characterized by comprising the steps of:

forming, on a first substrate, a diode that has an active layer made of InGaAlN and is capable of emitting blue or ultraviolet light;

forming, on a surface of the diode opposite to a surface thereof on which the first substrate is formed, a transparent electrode that allows transmission of light emitted from the diode;

forming a semiconductor layer on a second substrate made of a single crystal;

bonding a third substrate that allows transmission of visible light onto a surface of the semiconductor layer opposite to a surface thereof on which the second substrate is formed;

separating the second substrate from the semiconductor layer;

bonding together a surface of the transparent electrode opposite to a surface thereof on which the diode is formed, and a surface of the semiconductor layer opposite to a surface thereof on which the third substrate is formed; and

separating the first substrate from the diode,

wherein after the step of forming the third substrate, the method further comprises the step of forming a phosphor layer made of a phosphor material on a surface of the third substrate opposite to a surface thereof on which the semiconductor layer is formed.

32. The method for fabricating a semiconductor light emitting device according to claim 31,

wherein after the step of separating the first substrate from the diode, the method further comprises the step of forming, on a surface of the diode opposite to a surface thereof on which the transparent electrode is formed, an electrode made of Al, Ag, Rh, Pt, or an alloy or multilayer metal film including any of these metals.

35. The method for fabricating a semiconductor light emitting device according to claim 31,

wherein the step of separating the first substrate from the diode comprises the step of removing the first substrate by irradiating it with light from a surface of the first substrate opposite to a surface thereof on which the diode is formed.

36. The method for fabricating a semiconductor light emitting device according to claim 35,

wherein the light is a pulse-oscillated laser.

37. The method for fabricating a semiconductor light emitting device according to claim 35,

wherein the light is an emission line of a mercury lamp.

38. The method for fabricating a semiconductor light emitting device according to claim 31,

wherein the step of separating the first substrate from the diode comprises the step of removing the first substrate by polishing, thus separating the first substrate.

33. A method for fabricating a semiconductor light emitting device that emits white light, the method characterized by comprising the steps of:

forming, on a first substrate, a diode that has an active layer made of InGaAlN and is capable of emitting blue or ultraviolet light;

forming, on a surface of the diode opposite to a surface thereof on which the first substrate is formed, a transparent electrode that allows transmission of light emitted from the diode;

forming a plurality of semiconductor layers on a second substrate made of a single crystal;

bonding a third substrate that allows transmission of visible light onto a surface of the plurality of semiconductor layers opposite to a surface thereof on which the second substrate is formed;

separating the second substrate from the plurality of semiconductor layers;

bonding together a surface of the transparent electrode opposite to a surface thereof on which the diode is formed, and a surface of the plurality of semiconductor layers opposite to a surface thereof on which the third substrate is formed; and

separating the first substrate from the diode.

34. The method for fabricating a semiconductor light emitting device according to claim 33,

wherein after the step of separating the first substrate from the diode, the method further comprises the step of forming, on a surface of the diode opposite to a surface thereof on which the transparent electrode is formed, an electrode made of Al, Ag, Rh, Pt, or an alloy or multilayer metal film including any of these metals.