Light emitting device having a nitride compound semiconductor and a phosphor containing a garnet fluorescent material

• US 5,998,925 A
• Filed: 07/29/1997
• Issued: 12/07/1999
• Est. Priority Date: 07/29/1996
• Status: Expired due to Term

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Kagaku Kogyo Kabushiki Kaisha
• Inventors: Shimizu, Yoshinori, Moriguchi, Toshio, Sakano, Kensho, Noguchi, Yasunobu
• Primary Examiner(s): Patel, Vip
• Assistant Examiner(s): WILLIAMS, JOSEPH L
• Application Number:
  US08/902,725
• Time in Patent Office: 861 Days
• Field of Search: 313/498, 313/503, 313/501, 313/502, 257/103
• US Class Current: 313/503
• CPC Class Codes: C09K 11/7767 Chalcogenides
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0025 Diffusing sheet or layer; Prismatic sheet or layer
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01J 29/20 characterised by the luminescent material
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) 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 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/45 of an individual wire connector
• 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 2924/01067 : Holmium [Ho]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• CPC Class Codes: H01L 2924/12036 : PN diode
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/15747 : Copper [Cu] as principal constituent
• 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 2924/3011 : Impedance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• 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 33/50 : Wavelength conversion elements
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: H01L 33/504 : Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H05B 33/14 : characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: Y02B 20/00 : Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

The white light emitting diode comprising a light emitting component using a semiconductor as a light emitting layer and a phosphor which absorbs a part of light emitted by the light emitting component and emits light of wavelength different from that of the absorbed light, wherein the light emitting layer of the light emitting component is a nitride compound semiconductor and the phosphor contains garnet fluorescent material activated with cerium which contains at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from the group consisting of Al, Ga and In and, and is subject to less deterioration of emission characteristic even when used with high luminance for a long period of time.

Claims

1. A light emitting device, comprising a light emitting component and a phosphor capable of absorbing a part of light emitted by the light emitting component and emitting light of wavelength different from that of the absorbed light;

wherein said light emitting component comprises a nitride compound semiconductor represented by the formula;

In_i Ga_j Al_k N where 0≦

i, 0≦

j, 0≦

k and i+j+k=1 and said phosphor contains a garnet fluorescent material comprising

     1) at least one element selected from the group consisting of Y, Lu, Se, La, Gd and Sm, and

     2) at least one element selected from the group consisting of Al, Ga and In, and being activated with cerium.

2. A light emitting device according to claim 1, wherein the phosphor used contains an yttrium-aluminum-garnet fluorescent material containing Y and Al.

3. A light emitting device according to claim 1, wherein the phosphor is a fluorescent material represented by a general formula (Re_1-r Sm_r)₃ (Al_1-s Ga_s)₅ O₁₂ :

Ce, where 0≦

r<

1 and 0≦

s≦

1 and Re is at least one selected from Y and Gd.

4. A light emitting device according to claim 3, wherein the phosphor contains a fluorescent material represented by a general formula (Y_1-p-q-r Gd_p Ce_q SM_r)₃ (Al_1-s Ga_s)₅ O₁₂, where 0≦

p≦

0.8, 0.003≦

q≦

0.2, 0.0003≦

r≦

0.08 and 0≦

s≦

1.

5. A light emitting device according to claim 2, wherein the phosphor may contain two or more yttrium-aluminum-garnet fluorescent materials, activated with cerium, of different compositions including Y and Al.

6. A light emitting device according to claim 3, wherein the phosphor contains two or more fluorescent materials of different compositions represented by a general formula (Re_1-r Sm_r)₃ (Al_1-s Ga_s)₅ O₁₂ :

Ce, where 0≦

r<

1 and 0≦

s≦

1 and Re is at least one selected from Y and Gd.

7. A light emitting device according to claim 1, wherein the phosphor may contain a first fluorescent material represented by a general formula Y₃ (Al_1-s Ga_s)₅ O₁₂ :

Ce and a second fluorescent material represented by general formula Re₃ Al₅ O₁₂ ;

Ce, where 0≦

s≦

1 and Re is at least one element selected from the group consisting of Y, Ga and La.

8. A light emitting device according to claim 2, wherein the phosphor may be an yttrium-aluminum-garnet fluorescent material containing a first fluorescent material and a second fluorescent material, with each different parts of yttriums in said first fluorescent material and second fluorescent material being substituted with gadolinium.

9. A light emitting device according to claim 1, wherein the main emission peak of the light emitting component is set within the range from 400 nm to 530 nm and the main emission wavelength of the phosphor is set to be longer than the main emission peak of the light emitting component.

10. A light emitting device according to claim 9, wherein the light emitting layer of the light emitting component contains a gallium nitride semiconductor containing In, and the phosphor is an yttrium-aluminum-garnet fluorescent material wherein part of Al is substituted by Ga so that the proportion of Ga:

Al is within the range from 1;

1 to 4;

6 and part of Y is substituted by Gd so that the proportion of Y;

Gd is within the range from 4;

1 to 2;

3.

11. A light emitting device according to claim 1, which comprises a substantially rectangular optical guide plate being provided with a further light emitting component mounted on one side face thereof operatively associated with the phosphor and being substantially covered with a reflective material, except for one principal surface not being covered with a reflective material, wherein light emitted by the light emitting component is turned to planar light by the optical guide plate and the phosphor, and is output from the principal surface of the optical guide plate.

12. A light emitting device according to claim 1, which comprises a substantially rectangular optical guide plate, provided with a further light emitting component mounted on one side face thereof and the phosphor installed on one principal surface not covered with a reflective material, the other surfaces being substantially covered with a reflective material, wherein light emitted by the light emitting component is turned to planar light by the optical guide plate and the phosphor, and is output from the principal surface of the optical guide plate.

13. An LED display device comprising the light emitting devices according to one of claims 1 to 10 arranged in a matrix and a drive circuit which drives the LED display device according to display data which is input thereto.

14. A light emitting diode comprising:

a mount lead having a cup and a lead;

an LED chip mounted in the cup of the mount lead with one of electrodes being electrically connected to the mount lead;

a transparent coating material filling the cup to cover the LED chip; and

a light emitting diode having a molding material which covers the LED chip covered with the coating material including the cup of the mount lead, the inner lead and another electrode of the LED chip, wherein

the LED chip is a nitride compound semiconductor and the coating material contains at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, at least one element selected from the group consisting of Al, Ga and In and a phosphor made of garnet fluorescent material activated with cerium.

15. A light emitting diode according to claim 14, wherein the phosphor used contains an yttrium-aluminum-garnet fluorescent material that contains Y and Al.

16. A light emitting diode according to claim 14, wherein the phosphor is a fluorescent material represented by a general formula (Re_1-r Sm_r)₃ (Al_1-s Ga_s)₅ O₁₂ :

Ce, where 0≦

r≦

1 and 0≦

s≦

1 and Re is at least one element selected from the group consisting of Y and Gd.

17. A light emitting diode according to claim 14, wherein the fluorescent material is represented by a general formula (Y_1-p-q-r Gd_p Ce_q Sm_r)₃ (Al_1-s Ga_s)₅ O₁₂, where 0≦

p≦

0.8, 0.003≦

q≦

0.2, 0.0003≦

r≦

0.08 and 0≦

s≦

1.

18. A light emitting diode according to claim 15, wherein the phosphor contain two or more yttrium-aluminum-garnet fluorescent materials, activated with cerium, of different compositions including Y and Al.

19. A light emitting diode according to claim 16, wherein the phosphor contains two or more fluorescent materials of different compositions represented by a general formula (Re_1-r Sm_r)₃ (Al_1-s Ga_s)₅ O₁₂ :

Ce, where 0≦

r<

1 and 0≦

s≦

1 and Re is at least one selected from Y and Gd.

20. A light emitting diode according to claim 14, wherein the phosphor contains a first fluorescent material represented by a general formula Y₃ (Al_1-s Ga_s)₅ O₁₂ :

Ce and a second fluorescent material represented by a general formula Re₃ Al₅ O₁₂ ;

Ce, where 0≦

s≦

1 and Re is at least one element selected from the group consisting of Y, Ga and La.

21. A light emitting diode according to claim 18, wherein the phosphor contains an yttrium-aluminum-garnet fluorescent material containing a first fluorescent material and a second fluorescent material wherein part of yttrium is substituted with gadolinium to different degrees of substitution.

22. A light emitting diode according to claim 14, wherein the main emission peak of the light emitting component is set within the range from 400 nm to 530 nm and the main emission wavelength of the phosphor is set to be longer than the main emission peak of the light emitting component.

23. A white light emitting diode comprising a light emitting component using a semiconductor as a light emitting layer and a phosphor which absorbs a part of the light emitted by the light emitting component and emits light of wavelength different from that of the absorbed light, wherein the light emitting layer of the light emitting component is a nitride compound semiconductor and the phosphor contains garnet fluorescent material activated with cerium which contains at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from the group consisting of Al, Ga and In and, and wherein the main emission peak of the light emitting component is set within the range from 400 nm to 530 nm and the main emission wavelength of the phosphor is set to be longer than the main emission peak of the light emitting component.