Nitride phosphor and production process thereof, and light emitting device

• US 20090230840A1
• Filed: 05/14/2009
• Published: 09/17/2009
• Est. Priority Date: 03/22/2002
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Sakai, Kazuhiko, Tamaki, Hiroto, Naitou, Takahiro, Murazaki, Yoshinori, Kameshima, Masatoshi, Takashima, Suguru, Yamada, Motokazu
• Granted Patent: US 8,058,793 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: C01B 21/0602 with two or more other elements chosen from metals, silicon or boron
• CPC Class Codes: C01B 21/0821 Oxynitrides of metals, boron or silicon
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3227 Lanthanum oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/3852 Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
• CPC Class Codes: C04B 2235/3873 Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
• CPC Class Codes: C04B 2235/3895 Non-oxides with a defined oxygen content, e.g. SiOC, TiON
• CPC Class Codes: C04B 2235/764 Garnet structure A3B2(CO4)3
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C04B 35/584 based on silicon nitride
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77 containing rare earth metals
• CPC Class Codes: C09K 11/7702 : with zinc or cadmium
• CPC Class Codes: C09K 11/7703 : with alkaline earth metals
• CPC Class Codes: C09K 11/7728 : containing europium
• CPC Class Codes: C09K 11/773 : with zinc or cadmium
• CPC Class Codes: C09K 11/7731 : with alkaline earth metals
• CPC Class Codes: H01L 2224/32245 : the item being metallic
• CPC Class Codes: H01L 2224/45015 : being circular
• CPC Class Codes: H01L 2224/45124 : Aluminium (Al) as principal constituent
• 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 2224/45147 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/45169 : Platinum (Pt) 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 2224/48464 : the other connecting portion not on the bonding area also being a ball bond, i.e. ball-to-ball
• 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 2224/49107 : on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 : Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 : Applying permanent coating, e.g. protective coating
• 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 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01021 : Scandium [Sc]
• CPC Class Codes: H01L 2924/01037 : Rubidium [Rb]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01055 : Cesium [Cs]
• 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 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/20751 : larger or equal to 10 microns less than 20 microns
• CPC Class Codes: H01L 2924/20752 : larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/20753 : larger or equal to 30 microns less than 40 microns
• CPC Class Codes: H01L 2924/20754 : larger or equal to 40 microns less than 50 microns
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: Y02B 20/00 : Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

To provide a phosphor containing a comparatively much red component and having high light emitting efficiency, high brightness and further high durability, the nitride phosphor is represented by the general formula L_XM_YN_{((2/3)X+(4/3)Y)}:R or L_XM_YO_ZN_{((2/3)X+(4/3)Y−(2/3)Z)}:R (wherein L is at least one or more selected from the Group II Elements consisting of Mg, Ca, Sr, Ba and Zn, M is at least one or more selected from the Group IV Elements in which Si is essential among C, Si and Ge, and R is at least one or more selected from the rare earth elements in which Eu is essential among Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Lu.); contains the another elements.

Claims

1. A light emitting device comprising a light emitting element, a first phosphor which absorbs at least the portion of light from said light emitting element and emits light having a different wave length, and a second phosphor which absorbs at least the portion of light from said light emitting element and emits light having a different wave length, wherein the peak wave length of luminescence spectrum which said light emitting element has is situated at a longer wave length side than the peak wave length of excitation spectrum which the first phosphor has and the peak wave length of excitation spectrum which the second phosphor has.

2. The light emitting device according to claim 1;

wherein the peak wave length of luminescence spectrum of the light emitting element is shifted toward shorter wavelength side in accordance with the increase of electric current density.

3. The light emitting device according to claim 1;

wherein said first phosphor and said second phosphor have a nearly equal change of luminescence intensity in accordance with the change of ambient temperatures of the first phosphor and the second phosphor.

4. The light emitting device according to claim 3;

wherein the change of ambient temperatures of the first phosphor and the second phosphor is caused by the change of the input electric current to said light emitting element.

5. The light emitting device according to claim 1;

wherein the peak wave length of luminescence spectrum of said light emitting element is in a range of 350 nm to 530 nm.

6. The light emitting device according to claim 1;

wherein said first phosphor has a higher excitation efficiency at the short wavelength side of said wave length change than the long wavelength side within a range of the wave length change of the light emitting element which is generated at changing the electric current density of the light emitting element.

7. The light emitting device according to claim 1;

wherein said first phosphor has the peak wave length of excitation spectrum which the first phosphor has at the short wavelength side of said wave length change within a range of the wave length change of the light emitting element which is generated at changing the electric current density of the light emitting element.

8. The light emitting device according to claim 1;

wherein said first phosphor contains a yttrium-aluminum-garnet-base phosphor which contains Y and Al, and contains at least one of elements selected from the group consisting of Lu, Sc, La, Gd, Tb, Eu and Sm and at least one of elements selected from the group consisting of Ga and In and is activated by at least one of elements selected from the rare earth elements.

9. The light emitting device according to claim 1;

wherein the difference between the peak wave length of excitation spectrum which said first phosphor has and the peak wave length of excitation spectrum which said light emitting element has is 40 nm or less.

10. The light emitting device according to claim 1;

wherein said second phosphor has a higher excitation efficiency at the short wavelength side of said wave length change than the long wavelength side within a range of the wave length change of the light emitting element which is generated at changing the electric current density of the light emitting element.

11. The light emitting device according to claim 1;

wherein said second phosphor contains a nitride-base phosphor which contains N, and contains at least one of elements selected from the group consisting of Be, Mg, Ca, Sr, Ba and Zn and at least one elements selected from the group consisting of C, Si, Ge, Sn, Ti, Zr and Hf, and is activated by at least one of elements selected from the rare earth elements.

12. The light emitting device according to claim 1;

wherein said light emitting device is the light source of a back light for a liquid crystal display or a light source for illumination.