White light emitting element and white light source

• US 20050184298A1
• Filed: 02/18/2005
• Published: 08/25/2005
• Est. Priority Date: 02/19/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ueda, Tetsuzo
• Granted Patent: US 7,482,641 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• 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 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 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 2924/00012 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 2924/181 Encapsulation
• 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

Abstract

A white light source has an excitation light source and a white light emitting element provided at a position which allows the transmission of light from the excitation light source to generate white light through irradiation with the light from the excitation light source. The white light emitting element has a sapphire substrate made of sapphire or the like which transmits visible light, an InGaAlN semiconductor layer formed on a surface of the sapphire substrate to emit red light through irradiation with visible light, and a fluorescent layer formed on the surface opposite to the surface provided with the semiconductor layer to emit yellow light or green light through irradiation with visible light.

Claims

1. A white light emitting element for generating white light through irradiation with visible light, comprising:

a substrate which transmits the visible light;

a semiconductor layer formed on a surface of the substrate; and

a fluorescent layer formed on a surface of the substrate opposite to the surface thereof provided with the semiconductor layer or on a surface of the semiconductor layer, wherein

the fluorescent layer emits yellow light or green light through irradiation with the visible light and

the semiconductor layer emits red light through irradiation with the visible light.

4. The white light emitting element of claim 1 wherein the fluorescent layer for emitting the yellow light or the green light contains a YAG fluorescent material.

6. The white light emitting element of claim 1, which emits white light composed of the red light, the yellow light or the green light, and the blue light through irradiation with the visible light or with the ultraviolet light.

10. The white light emitting element of claim 1, wherein

the semiconductor layer contains impurities and

the semiconductor layer emits light in a visible region through recombination between an electron and a hole via an energy level resulting from the impurities through irradiation with the visible light or with the ultraviolet light.

11. The white light emitting element of claim 10, wherein the semiconductor layer contains any one or two or all of Si, Mg, and Zn each as an impurity.

12. The white light emitting element of claim 1, wherein

the semiconductor layer contains impurities and

the semiconductor layer emits light in a visible region via inner shell transition of the impurities through irradiation with the visible light or the ultraviolet light.

13. The white light emitting element of claim 12, wherein the semiconductor layer contains any one or two or all of Eu, Sm and Yb each as the impurity.

14. The white light emitting element of claim 12, wherein the impurity is introduced to the semiconductor layer by ion implantation.

15. The white light emitting element of claim 1, wherein the semiconductor layer is made of Al_xGa_yIn_(1-x-y)N (0≦

x≦

1, 0≦

y≦

1, 0 ≦

1-x-y ≦

1).

16. The white light emitting element of claim 1, wherein the substrate which transmits the visible light or the ultraviolet light is made of sapphire.

2. A white light emitting element for generating white light through irradiation with ultraviolet light, comprising:

a substrate which transmits the ultraviolet light;

a semiconductor layer formed on a surface of the substrate; and

a fluorescent layer formed on a surface of the substrate opposite to the surface thereof provided with the semiconductor layer or on a surface of the semiconductor layer, wherein

the fluorescent layer emits yellow light or green light and blue light through irradiation with the ultraviolet light and

the semiconductor layer emits red light through irradiation with the ultraviolet light.

3. The white light emitting element of claim 2, wherein

the fluorescent layer contains a plurality of fluorescent materials and

the fluorescent materials emit light in different colors through irradiation with the ultraviolet light.

5. A white light emitting element for generating white light through irradiation with ultraviolet light, comprising:

a substrate which transmits the ultraviolet light; and

a semiconductor layer formed on a surface of the substrate, wherein

the semiconductor layer emits red light, yellow light or green light, and blue light through irradiation with the ultraviolet light.

7. A white light emitting element for generating white light through irradiation with ultraviolet light or visible light, comprising:

a substrate which transmits the ultraviolet light or the visible light; and

a semiconductor layer formed on a surface of the substrate, wherein

the semiconductor layer is composed of a plurality of compound semiconductor layers having different element composition ratios and

each of the compound semiconductor layers is formed to have a forbidden band width the value of which monotonously increases or decreases in a direction from the surface of the substrate toward a surface of the semiconductor layer.

8. The white light emitting element of claim 7, wherein a lattice constant in a crystal structure of each of compound semiconductors composing the individual compound semiconductor layers has a constant value.

9. The white light emitting element of claim 7, wherein light emitted from individual compound semiconductors has different wavelengths due to the different element composition ratios of the individual compound semiconductors.

17. A white light source comprising:

an excitation light source; and

a white light emitting element for generating white light through irradiation with light from the excitation light source, wherein

the excitation light source emits visible light,

the white light emitting element comprises;

a substrate which transmits the light from the excitation light source;

a semiconductor layer formed on a surface of the substrate; and

a fluorescent layer formed on a surface of the substrate opposite to the surface thereof provided with the semiconductor layer or on a surface of the semiconductor layer,

the fluorescent layer emits yellow light or green light through irradiation with the visible light, and

the semiconductor layer emits red light through irradiation with the visible light.

20. The white light source of claim 17, wherein the fluorescent layer for emitting the yellow light or the green light contains a YAG fluorescent material.

22. The white light source of claim 17, which emits white light composed of the red light, the yellow light or the green light, and the blue light through irradiation with the visible light or with the ultraviolet light.

26. The white light source of claim 17, wherein

the semiconductor layer contains impurities and

the semiconductor layer emits light in a visible region through recombination between an electron and a hole via an energy level resulting from the impurities through irradiation with the visible light or with the ultraviolet light.

27. The white light source of claim 26, wherein the semiconductor layer contains any one or two or all of Si, Mg, and Zn each as an impurity.

28. The white light source of claim 17, wherein

the semiconductor layer contains impurities and

the semiconductor layer emits light in a visible region via inner shell transition of the impurities through irradiation with the visible light or the ultraviolet light.

29. The white light source of claim 28, wherein the semiconductor layer contains any one or two or all of Eu, Sm and Yb each as the impurity.

30. The white light source of claim 28, wherein the impurity is introduced to the semiconductor layer by ion implantation.

31. The white light source of claim 17, wherein the semiconductor layer is made of Al_xGa_yIn_(1-x-y)N (0≦

x≦

, 0≦

y≦

1, 0≦

1-x-y≦

1).

32. The white light source of claim 17, wherein the substrate which transmits the visible light or the ultraviolet light is made of sapphire.

18. A white light source comprising:

an excitation light source; and

a white light emitting element for generating white light through irradiation with light from the excitation light source, wherein

the excitation light source emits ultraviolet light,

the white light emitting element comprises;

a substrate which transmits the light from the excitation light source;

a semiconductor layer formed on a surface of the substrate; and

a fluorescent layer formed on a surface of the substrate opposite to the surface thereof provided with the semiconductor layer or on a surface of the semiconductor layer,

the fluorescent layer emits yellow light or green light and blue light through irradiation with the ultraviolet light, and

the semiconductor layer emits red light through irradiation with the ultraviolet light.

19. The white light source of claim 18, wherein

the fluorescent layer contains a plurality of fluorescent materials and

the fluorescent materials emit light in different colors through irradiation with the ultraviolet light.

21. A white light source comprising:

an excitation light source; and

a white light emitting element for generating white light through irradiation with light from the excitation light source, wherein

the excitation light source emits ultraviolet light,

the white light emitting element comprises;

a substrate which transmits the light from the excitation light source; and

a semiconductor layer formed on a surface of the substrate, and

the semiconductor layer emits red light, yellow light or green light, and blue light through irradiation with the ultraviolet light.

23. A white light source comprising:

an excitation light source; and

a white light emitting element for generating white light through irradiation with light from the excitation light source, wherein

the excitation light source emits ultraviolet light or visible light,

the white light emitting element comprises;

a substrate which transmits the light from the excitation light source; and

a semiconductor layer formed on a surface of the substrate,

the semiconductor layer is composed of a plurality of compound semiconductor layers having different element composition ratios, and

each of the compound semiconductor layers is formed to have a forbidden band width the value of which monotonously increases or decreases in a direction from the surface of the substrate toward a surface of the semiconductor layer.

24. The white light source of claim 23, wherein a lattice constant in a crystal structure of each of compound semiconductors composing the individual compound semiconductor layers has a constant value.

25. The white light source of claim 23, wherein light emitted from individual compound semiconductors has different wavelengths due to the different element composition ratios of the individual compound semiconductors, the white light emitting element emitting white light composed of the plurality of light components emitted from the individual compound semiconductors.