Light emitting device and display

• US 8,309,375 B2
• Filed: 11/09/2010
• Issued: 11/13/2012
• Est. Priority Date: 07/29/1996
• Status: Expired due to Fees

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Shimizu, Yoshinori, Sakano, Kensho, Noguchi, Yasunobu, Moriguchi, Toshio
• Primary Examiner(s): Garber, Charles
• Assistant Examiner(s): MUSTAPHA, ABDULFATTAH B
• Application Number:
  US12/942,792
• Publication Number:
  US 20110053299A1
• Time in Patent Office: 735 Days
• Field of Search: 438 21- 27, 257/98, 257/E33.044, 257/E33.059, 349 69-105
• US Class Current: 438/21
• 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

A method for manufacturing a light emitting device comprises: preparing a light emitting component having an active layer of a semiconductor, the active layer comprising a gallium nitride based semiconductor containing indium and being capable of emitting a blue color light; preparing a phosphor capable of absorbing a part of the blue color light emitted from the light emitting component and emitting a yellow color light, wherein selection of the phosphor is controlled based on an emission wavelength of the light emitting component; and combining the light emitting component and the phosphor so that the blue color light from the light emitting component and the yellow color light from the phosphor are mixed to make a white color light.

Claims

1. A method for manufacturing a light emitting device comprising:

preparing a light emitting component having an active layer of a semiconductor, said active layer comprising a gallium nitride based semiconductor containing indium and being capable of emitting a blue color light having a spectrum with a peak wavelength within the range from 420 to 490 nm;

preparing a phosphor capable of absorbing a part of the blue color light emitted from said light emitting component and emitting a yellow color light having a broad emission spectrum comprising a peak wavelength existing around the range from 510 to 600 nm and a tail continuing beyond 700 nm, wherein selection of said phosphor is controlled based on an emission wavelength of said light emitting component; and

combining said light emitting component and said phosphor so that the blue color light from said light emitting component and the yellow color light from said phosphor are mixed to make a white color light, wherein a chromaticity point of the white color light is on a straight line connecting a point of chromaticity of the blue color light and a point of chromaticity of the yellow color light, and

wherein a content of said phosphor in said light emitting device is selected to obtain a desired chromaticity of the white color light.

2. The method for manufacturing a light emitting device according to claim 1, wherein said phosphor comprises a garnet fluorescent material activated with cerium.

3. The method for manufacturing a light emitting device according to claim 1, wherein said phosphor comprises two or more kinds of fluorescent materials.

4. The method for manufacturing a light emitting device according to claim 1, wherein the emission spectrum of said phosphor comprises a peak wavelength existing around the range from 530 to 570 nm and a tail continuing beyond 700 nm.

5. The method for manufacturing a light emitting device according to claim 1, wherein said phosphor comprises an yttrium-aluminum-garnet fluorescent material containing Y and Al.

6. The method for manufacturing a light emitting device according to claim 1, wherein said phosphor has a crystal structure.

7. The method for manufacturing a light emitting device according to claim 1, wherein the active layer of said light emitting component has a single quantum well or multi quantum well structure.

8. The method for manufacturing a light emitting device according to claim 1, wherein the active layer of said light emitting component comprises InGaN.

9. The method for manufacturing a light emitting device according to claim 1, wherein said light emitting device is capable of emitting white light substantially along the black body radiation locus.

10. The method for manufacturing a light emitting device according to claim 1, further comprising:

controlling emission color of said light emitting device by changing a content of said phosphor with respect to a content of a resin in a coating material.

11. The method for manufacturing a light emitting device according to claim 1, wherein said step of controlling selection of said phosphor is used to reduce variation in the emission wavelength of said light emitting device, by compensating for a variation of the emission wavelength of said light emitting component.

12. The method for manufacturing a light emitting device according to claim 3, further comprising:

controlling compositions or quantities of light emitting components and fluorescent materials included in said light emitting device, to control color emitted by said light emitting device.

13. The method for manufacturing a light emitting device according to claim 3, wherein the emission wavelength of the fluorescent materials are selected so that said light emitting device produces RGB components with high luminance.

14. The method for manufacturing a light emitting device according to claim 13, wherein

the emission spectrum of one fluorescent material comprises a peak wavelength around 510 nm, and the emission spectrum tails out to around 700 nm, and

the emission spectrum of a second fluorescent material comprises a peak wavelength around 600 nm, and the emission spectrum tails out to around 750 nm, so that said light emitting device produces RGB components with high luminance.

15. The method for manufacturing a light emitting device according to claim 3, further comprising mixing said two or more kinds of fluorescent materials.

16. The method for manufacturing a light emitting device according to claim 3, wherein said two or more kinds of fluorescent materials are arranged independently to adjust color by laminating the layers of fluorescent materials.

17. The method for manufacturing a light emitting device according to claim 3, wherein one of said fluorescent materials absorbs light of a shorter wavelength and another of said fluorescent materials absorbs light of a longer wavelength, and said fluorescent material that absorbs light of a longer wavelength is arranged away from said light emitting component, while said fluorescent material that absorbs light of a shorter wavelength is arranged near said light emitting component.

18. The method for manufacturing a light emitting device according to claim 1, wherein said phosphor is a fluorescent material represented by formula (Re₁₋

rSm_r)₃ (Al<sub>1−

s</sub>Ga_s)₅O₁₂;

Ce where 0 ≦

r<

1, 0 ≦

s≦

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

19. The method for manufacturing a light emitting device according to claim 1, further comprising:

controlling compositions or quantities of light emitting components included in said light emitting device and controlling composition of said phosphor, to control color emitted by said light emitting device.