WO2000076005A1 - Photon recycling semiconductor multi-wavelength light-emitting diodes - Google Patents

Photon recycling semiconductor multi-wavelength light-emitting diodes Download PDF

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Publication number
WO2000076005A1
WO2000076005A1 PCT/US2000/015412 US0015412W WO0076005A1 WO 2000076005 A1 WO2000076005 A1 WO 2000076005A1 US 0015412 W US0015412 W US 0015412W WO 0076005 A1 WO0076005 A1 WO 0076005A1
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Prior art keywords
source
light
semiconductor material
wavelength
semiconductor
Prior art date
Application number
PCT/US2000/015412
Other languages
French (fr)
Inventor
E. Fred Schubert
Xiaoyun Gxy Guo
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Trustees Of Boston University
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Publication date
Priority to US13764699P priority Critical
Priority to US60/137,646 priority
Application filed by Trustees Of Boston University filed Critical Trustees Of Boston University
Publication of WO2000076005A1 publication Critical patent/WO2000076005A1/en

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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/08Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L25/00Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
    • H01L25/03Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes
    • H01L25/04Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes the devices not having separate containers
    • H01L25/075Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
    • H01L25/0756Stacked arrangements of devices
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/0002Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A combined light of a white light impression achieved with two semiconductors rather than a semiconductor and a phosphor, dye or polymer converter. There result two substantially monochromatic radiations from the first and second semiconductors or radiation sources. The radiation from two such sources (42, 40) is according to CIE chromaticity diagrams to give the impression of white light.

Description

TITLE OF THE INVENTION

PHOTON RECYCLING SEMICONDUCTOR MULTI-WAVELENGTH LIGHT- EMITTING DIODES

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the priority of U.S. Provisional Patent Application No. 60/137,646 filed June 4, 1999 entitled PHOTON RECYCLING SEMICONDUCTOR MULTI-WAVELENGTH LIGHT-EMITTING DIODES

ACKNOWLEDGEMENT OF GOVERNMENT SUPPORT

This invention was made with Government Support under Contract Number ECS 9714047 awarded by the

National Science Foundation. The Government has certain rights in the invention.

BACKGROUND OF THE INVENTION

A source of white light from the combination of two or more substantially monochromatic light sources, as that term is known in the art, is of significant value for use in displays, instruments, and general illumination, particularly where it replaces inefficient incandescent sources

In prior devices using an LED semiconductor primary emitter, a non-semiconductor material such as a phosphor, a dye, or a polymer is provided to respond to light from the LED emitter and convert it into a fairly broad band centered at a longer wavelength than the LED primary emitter light. Together the primary emitter and the wavelength converter materials can create the impression of a nearly white light. Such phosphors increase the cost of a unit. Dyes on the other hand lack long-term stability. Polymers lack sufficient electrical conductivity to carry heavy electrical loads required for high-intensity light outputs.

BRIEF SUMMARY OF THE INVENTION

According to the invention, white light or nearly white light is created with two semiconductor active regions rather than a semiconductor and a phosphor, dye or polymer converter. This results in an emission spectrum consisting of two substantially monochromatic emission bands from the first and second semiconductor active regions or radiation sources. The radiation wavelength from two such sources is selected according to the CIE chromaticity diagrams to give the impression of white light or of another color not located on the perimeter of the chromaticity diagram.

A typical device for providing the light has a first semiconductor formed of doped GalnN (gallium indium nitride) or GaN with a P type confinement region and an N type confinement region and having an active region between the two confinement regions. The active region is stimulated to emit in the blue by an electrical current passing through it. The blue light emits in generally all directions.

A second semiconducting active region is located adjacent to the first semiconductor layers, but can be separated by a sapphire transparent layer upon which the semiconductor layers were initially grown.

The second semiconductor layer can be wafer bonded to the sapphire layer and originally grown on a GaAs substrate that is subsequently removed. The second region is typically AlGalnP (aluminum gallium indium phosphorus) and acts upon the incident light or some of it emitter by the first region in the same way an active P/N junction region responds to the energy in an electrical current to reemit or recycle the light to a longer wavelength.

In an alternative approach, the second active region is also made of GalnN and in that case the two active regions can be grown in one single growth run.

DESCRIPTION OF THE DRAWING

These and other features of the invention are described below in the detailed description in conjunction with the drawing of which:

Fig. 1 is an emission diagram of a prior art device;

Fig. 2 is a chromaticity diagram for phosphor based LED emitters; Fig. 3 is an emission diagram of a white light emitter of the invention using photon recycling secondary emission;

Fig. 4 is a chromaticity diagram for a photon recycling LED of the invention; Fig. 5 illustrates the construction go a photon recycling LED for producing white light according to the invention; Fig. 6 is a diagram of emission wavelength as a function of material composition useful in the present invention;

Fig. 7 is a diagram useful in understanding principles of power ratio in the invention;

Fig. 8 is a diagram illustrating power ratio values as a function of the wavelength of emission from LED light used in photon recycling in practicing the invention; Fig. 9 illustrates the relationship between material composition and bandgap energy; and

Figs. 10A and 10b illustrate the use of the invention in arrays and large area emitters.

DETAILED DESCRIPTION

The present invention provides a source of white light from the combination of two substantially monochromatic light sources as that term is known in the art by combining the light, typically blue, from a first short wavelength LED source with the light, typically yellow, from secondary emission in a semiconductor material stimulated by incident light of the short wavelength. The use of only two sources reduces the cost compared to prior devices using a combination of the light, for example, from three or more separately activated LEDs.

In other prior devices using a semiconductor primary emitter, a non semiconductor material such as a phosphor, a dye, or a polymer is provided to respond to light from an LED emitter and convert it into a fairly broad band as illustrated in Fig.l where curve 12 represents that of a blue light LED emitter and curve 14 the emission of a phosphor converter that creates the impression of a nearly white light over the broad emission band plus the LED light. Such phosphors increase the cost of a unit. Dyes on the other hand lack long term stability. Polymers lack sufficient electrical conductivity to carry heavy electrical loads and high intensity light outputs.

A chromaticity diagram such as illustrated in Fig. 2 can be used to understand the principle of achieving white light from a range of light wavelengths such as with phosphors and blue LED sources. The curve 16 starting in the lower left at short or blue wavelengths progresses clockwise with increasing wavelength. The dot 16 at the blue side of the center indicates a perceived light color from the combination of LED and phosphor sources about the curve 16.

According to the invention, a combined light of a white light impression is achieved with two semiconductors rather than a semiconductor and a phosphor, dye or polymer converter. There results two substantially monochromatic radiations, 20 and 22 respectively from the first and second semiconductors or radiation sources. The radiation from two such sources is illustrated in the chromaticity diagram of Fig. 4, with the wavelengths 24 and 26 of the first and second sources combining to give the impression of white light at 28. The chromaticity diagram includes a region 30 about the white resultant at 28 that gives a satisfactory impression of white, depending upon the application. A typical device for providing the light illustrated in Figs. 3 and 4 is shown in Fig. 5. A first semiconductor is formed of doped GalnN (gallium indium nitride) or GaN with P type region 32 and N type region 34 having a P/N junction 36 or active region which is stimulated to emit in the blue by an electrical current passing through it from respective contacts 38 and 40. The blue light emits in generally all directions but can be directed as desired. A second semiconducting active region 42 is fabricated adjacent to the first semiconductor layers 32-34, but separated by a sapphire transparent layer 44 upon which the layers 32-36 were initially grown according to known fabrication techniques. The layer 42 is typically wafer bonded to the sapphire layer 44 and originally grown on a GaAs substrate that is subsequently removed by chemically assisted polishing and wet etching. Region 42 is typically AlGalnP (aluminum gallium indium phosphorus) . Region 42 acts upon the incident light or some of it from the region 36 through a conductin to valence band transition, such as an active P/N junction region responds to the energy in an electrical current, to reemit or recycle the photons to a longer wavelength. The wavelengths selected can be any that place the resulting combined radiation into the area 32 of Fig. 4 from sources with wavelengths on opposite sides of the curve 16 and appropriate power levels at each wavelength. Compositions of the material for the primary and secondary emitting semiconductor, such as those noted above, are a function of the elemental concentrations. Fig. 5 is one chart for the combining of AIN, GaN and InN along lines 50, 52 and 54 showing approximate color outputs over a range of concentrations and materials. Other materials and their general wavelength of emissions are illustrated in Fig. 9 below. Preferably, blue emission in a region centered within the range of 420 nm - 480 nm has been found advantageous for the primary emitter and within a color complimentary wavelength in the 500 's nm for the secondary emitter. For the primary emitter GalnN as the semiconductor material is useful for this light with silicon doping for N-type confinement regions and magnesium doping for the P-type confinement regions. The yellow region will typically be AlGalnP with concentrations of In varied for the color yellow. A sapphire substrate as noted above is preferable although other materials such as GaN or SiC are possible. For the semiconducting material other combinations of other elements are also possible such as AlGaAs . Fig. 9 presents the color characteristics of other materials that those skilled in the art could select from. In an alternative approach, the second active region is also made of GalnN and in that case the two active regions can be grown in one single growth run. Fig. 7 shows diagramatically the division of power between the primary LED emitter 60 and the secondary semiconductor emitter 62. The perception of white light is also a function of the relative power from the two sources, Px and P2. Their ratio, R, is selected to insure whiteness in the output and is based on the relationship shown in Fig 8 where curve 64 gives the power ratio as a function of the wavelength of the primary LED color. The thickness of the layer 42 for the active secondary emitter will vary the power ratio by causing more or less of the photons from the primary LED to be recycled in the active area. For the final chip, the ratio can be adjusted empirically for the desired whiteness.

Large versions or arrays of chips of the type shown in Fig. 5 can be arranged to cause an augmented light output for applications such as panel lights, display lights or ceiling lights, requiring high efficiency white light. Fig. 10A shows a single chip 70 of significant size that can be used for this purpose, while Fig. 10B shows an array 72 of smaller chips 74 assembled to provide an increased intensity of white light output.

The chip of the invention can additionally have plural secondary layers to produce three colors that combine to form white in perception, or some other color.

Claims

CLAIMSIN THE CLAIMS
1. A single chip source of multi-chromatic output light having the visual perception of light inside the periphery of the CIE chromaticity diagram comprising: a first semiconductor material in said chip responsive to energization to emit light of a first wavelength; at least one photon recycling second semiconductor material in said chip responsive to radiation of said first wavelength to emit light of a second wavelength longer than the first by photon recycling and along at least said path; said path having said first wavelength at a first power lever and said second wavelength at a second power;
Said first and second wavelengths and first and second power levels combining to provide output light perception.
2. The source of claim 1 wherein said first and second wavelengths are complementary colors on a CIE chromaticity diagram and said putput light is at least near white.
3. The source of claim 1 where the power ratios of said first and second wavelength emissions satisfy a criteria for said at least near white light.
. The source of claim 1 wherein said first semiconductor material consists of GalnN.
5. The source of claim 4 wherein said first semiconductor material has an active region formed between P-type and N-type regions thereof.
6. The source of claim 5 wherein said P-type region is doped with magnesium.
7. The source of claim 5 wherein said N-type region is doped with silicon.
8. The source of claim 1 wherein said second semiconductor material is a combination of plural of the elements Al, Ga, In, N, and P, for example AlInGaP or GalnN.
9. The source of claim 1 wherein said first and second semiconductor materials are separated by a transparent material.
10. The source of claim 9 wherein said transparent material is selected from the group consisting of combinations of at least some of Ga, N, Si, and C, for example GalnN or GaN.
11. The source of claim 9 wherein said transparent material includes sapphire.
12. The source of claim 1 wherein said first semiconductor material is a combination of Ga, In, and N.
13. The source of claim 12 wherein said first semiconductor material is adapted for emitting in the range of 20 nm - 480 nm.
14. The source of claim 1 wherein said second semiconductor material is a combination of Al, Ga, In, N and P.
15. The source of claiml4 wherein said second semiconducting material is adapted for emitting in a complementary color range to the range of 420 nm - 480 nm.
16. The source of claim 1 further including first and second electrodes contacting said chip to apply electrical current to said first semiconductor material as said energization.
17. The source of claim 5 further including first and second electrodes contacting said P-type and N-type regions for the application of electrical current thereto as said energization.
18. The source of claim 1 further including plural second semiconductor materials.
19. An array of chips of the type of claim 1 providing said at least near white light.
PCT/US2000/015412 1999-06-04 2000-06-02 Photon recycling semiconductor multi-wavelength light-emitting diodes WO2000076005A1 (en)

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US13764699P true 1999-06-04 1999-06-04
US60/137,646 1999-06-04

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1132977A2 (en) * 2000-03-10 2001-09-12 Kabushiki Kaisha Toshiba Semiconductor light emitting device and method for manufacturing same
JP2003060233A (en) * 2001-08-14 2003-02-28 Sony Corp Semiconductor light-emitting element, manufacturing method therefor, and semiconductor light-emitting device
EP1473771A1 (en) * 2003-04-14 2004-11-03 Shi-Ming Chen Color mixing light emitting diode
US7064354B2 (en) 2003-01-02 2006-06-20 Epitech Technology Corporation Color mixing light emitting diode
JP2008124504A (en) * 2003-06-05 2008-05-29 Matsushita Electric Ind Co Ltd Semiconductor light-emitting element, and method of manufacturing the same
JP2008227552A (en) * 2004-02-19 2008-09-25 Matsushita Electric Ind Co Ltd White light source
US7700938B2 (en) 2004-12-09 2010-04-20 3M Innovative Properties Company Adapting short-wavelength LED's for polychromatic, broadband, or “white” emission
US7719015B2 (en) 2004-12-09 2010-05-18 3M Innovative Properties Company Type II broadband or polychromatic LED's
US7745814B2 (en) 2004-12-09 2010-06-29 3M Innovative Properties Company Polychromatic LED's and related semiconductor devices
WO2010129464A1 (en) * 2009-05-05 2010-11-11 3M Innovative Properties Company Re-emitting semiconductor carrier devices for use with leds and methods of manufacture
JP2011040794A (en) * 2005-01-14 2011-02-24 Au Optronics Corp White-light emitting device, and method of manufacturing the same
CN102097553A (en) * 2010-12-03 2011-06-15 北京工业大学 Sapphire substrate-based single chip white light emitting diode
JP2012060165A (en) * 2011-12-14 2012-03-22 Sony Corp Semiconductor light emitting element, manufacturing method for semiconductor light emitting element, and semiconductor light emitting device
US8304976B2 (en) 2009-06-30 2012-11-06 3M Innovative Properties Company Electroluminescent devices with color adjustment based on current crowding
US8541803B2 (en) 2009-05-05 2013-09-24 3M Innovative Properties Company Cadmium-free re-emitting semiconductor construction
US8629611B2 (en) 2009-06-30 2014-01-14 3M Innovative Properties Company White light electroluminescent devices with adjustable color temperature
CN104393131A (en) * 2014-11-07 2015-03-04 深圳市九洲光电科技有限公司 Optical pumping white-light LED and preparation method thereof
US8994071B2 (en) 2009-05-05 2015-03-31 3M Innovative Properties Company Semiconductor devices grown on indium-containing substrates utilizing indium depletion mechanisms

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US5813752A (en) * 1997-05-27 1998-09-29 Philips Electronics North America Corporation UV/blue LED-phosphor device with short wave pass, long wave pass band pass and peroit filters
US5898185A (en) * 1997-01-24 1999-04-27 International Business Machines Corporation Hybrid organic-inorganic semiconductor light emitting diodes
US5952681A (en) * 1997-11-24 1999-09-14 Chen; Hsing Light emitting diode emitting red, green and blue light
US5966393A (en) * 1996-12-13 1999-10-12 The Regents Of The University Of California Hybrid light-emitting sources for efficient and cost effective white lighting and for full-color applications

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Publication number Priority date Publication date Assignee Title
US5739552A (en) * 1994-10-24 1998-04-14 Mitsubishi Denki Kabushiki Kaisha Semiconductor light emitting diode producing visible light
US5966393A (en) * 1996-12-13 1999-10-12 The Regents Of The University Of California Hybrid light-emitting sources for efficient and cost effective white lighting and for full-color applications
US5898185A (en) * 1997-01-24 1999-04-27 International Business Machines Corporation Hybrid organic-inorganic semiconductor light emitting diodes
US5813752A (en) * 1997-05-27 1998-09-29 Philips Electronics North America Corporation UV/blue LED-phosphor device with short wave pass, long wave pass band pass and peroit filters
US5952681A (en) * 1997-11-24 1999-09-14 Chen; Hsing Light emitting diode emitting red, green and blue light

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1132977A2 (en) * 2000-03-10 2001-09-12 Kabushiki Kaisha Toshiba Semiconductor light emitting device and method for manufacturing same
EP1132977A3 (en) * 2000-03-10 2003-05-07 Kabushiki Kaisha Toshiba Semiconductor light emitting device and method for manufacturing same
US6815725B2 (en) 2000-03-10 2004-11-09 Kabushiki Kaisha Toshiba Semiconductor light emitting device having a fluorescent material emitting light of a secondary wavelength
JP2003060233A (en) * 2001-08-14 2003-02-28 Sony Corp Semiconductor light-emitting element, manufacturing method therefor, and semiconductor light-emitting device
US7064354B2 (en) 2003-01-02 2006-06-20 Epitech Technology Corporation Color mixing light emitting diode
EP1473771A1 (en) * 2003-04-14 2004-11-03 Shi-Ming Chen Color mixing light emitting diode
JP2008124504A (en) * 2003-06-05 2008-05-29 Matsushita Electric Ind Co Ltd Semiconductor light-emitting element, and method of manufacturing the same
JP2008227552A (en) * 2004-02-19 2008-09-25 Matsushita Electric Ind Co Ltd White light source
US7700938B2 (en) 2004-12-09 2010-04-20 3M Innovative Properties Company Adapting short-wavelength LED's for polychromatic, broadband, or “white” emission
US7700939B2 (en) 2004-12-09 2010-04-20 3M Innovative Properties Company Adapting short-wavelength LED's for polychromatic, broadband, or “white” emission
US7719015B2 (en) 2004-12-09 2010-05-18 3M Innovative Properties Company Type II broadband or polychromatic LED's
US7737430B2 (en) * 2004-12-09 2010-06-15 3M Innovative Properties Company Adapting short-wavelength LED's for polychromatic, broadband, or “white” emission
US7902543B2 (en) * 2004-12-09 2011-03-08 3M Innovative Properties Company Adapting short-wavelength LED's for polychromatic, broadband, or “white” emission
US7745814B2 (en) 2004-12-09 2010-06-29 3M Innovative Properties Company Polychromatic LED's and related semiconductor devices
JP2011040794A (en) * 2005-01-14 2011-02-24 Au Optronics Corp White-light emitting device, and method of manufacturing the same
WO2010129464A1 (en) * 2009-05-05 2010-11-11 3M Innovative Properties Company Re-emitting semiconductor carrier devices for use with leds and methods of manufacture
US8994071B2 (en) 2009-05-05 2015-03-31 3M Innovative Properties Company Semiconductor devices grown on indium-containing substrates utilizing indium depletion mechanisms
US9293622B2 (en) 2009-05-05 2016-03-22 3M Innovative Properties Company Re-emitting semiconductor carrier devices for use with LEDs and methods of manufacture
US8541803B2 (en) 2009-05-05 2013-09-24 3M Innovative Properties Company Cadmium-free re-emitting semiconductor construction
US8304976B2 (en) 2009-06-30 2012-11-06 3M Innovative Properties Company Electroluminescent devices with color adjustment based on current crowding
US8629611B2 (en) 2009-06-30 2014-01-14 3M Innovative Properties Company White light electroluminescent devices with adjustable color temperature
CN102097553A (en) * 2010-12-03 2011-06-15 北京工业大学 Sapphire substrate-based single chip white light emitting diode
JP2012060165A (en) * 2011-12-14 2012-03-22 Sony Corp Semiconductor light emitting element, manufacturing method for semiconductor light emitting element, and semiconductor light emitting device
CN104393131A (en) * 2014-11-07 2015-03-04 深圳市九洲光电科技有限公司 Optical pumping white-light LED and preparation method thereof

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