US007535028B2
`
`(12) Ulllted States Patent
`Fan et a].
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 7,535,028 B2
`May 19, 2009
`
`(54) MICRO-LED BASED HIGH VOLTAGE AC/DC
`INDICATOR LAMP
`
`(75) IIWBIIIOFSI Zhaoyang Fall, Manhattan, KS (Us);
`H_0I1gXiI1gJiaI1g,Manha?an,K$ (Us);
`Jmgy“ L1n> Manhattan’ KS (Us)
`_
`_
`Llghtlng, L.LC., Manhattan,
`
`.
`(73) Ass1gnee.
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) APP1-N9-1 11/102,273
`
`(22) Filed:
`
`Apr. 8, 2005
`
`(65)
`
`Prior Publication Data
`
`US 2006/0169993 A1
`
`Aug. 3, 2006
`
`3/1999 Nakamura et a1.
`5,877,558 A
`7/1999 Ohba et a1. ............... .. 257/103
`5,929,466 A *
`9/1999 Strite
`5,952,680 A
`9/1999 Nakamura et al.
`5,955,748 A
`5,966,393 A 10/1999 Hide etal.
`6,054,724 A
`4/2000 Ogihara 61 a1.
`6,093,965 A
`7/2000 Nakamura et al.
`6,410,940 B1
`6/2002 Jiang et 31‘
`
`6,410,942 B1* 6/2002 Thibeault et al. ............ .. 257/88
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`
`5-63233
`
`* 3/1993
`
`(Continued)
`
`Related US. Application Data
`
`OTHER PUBLICATIONS
`
`(60) Provisional application NO‘ 60/649’827’ ?led on Feb‘
`3’ 2005'
`
`(51) Int. Cl.
`(2006.01)
`H01L 33/00
`(52) US. Cl. ........................... .. 257/88; 257/282;7/2E5275/9092;
`'
`(58) Field of Classi?cation Search ........... .. 257/88i89,
`
`Jeon, “A novel fabrication method for a 64 X 64 matrix addressable
`GaN-based micro-LED array,” phys. stat. S01. (a) 200, N0. 1, 79-82
`(2003).*
`
`(Continued)
`Primary ExamineriA. Sefer
`74 All
`A 2
`F' iL thr &G LLP
`(
`)
`Omey’ gen’ or m” a Op
`age
`
`See appl1cat1on ?le for complete search h1story.
`
`(56)
`
`References Cited
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`5,767,581 A
`6/1998 Nakamuraetal.
`5,773,130 A
`6/1998 S0 et a1.
`
`An AC/DC indicator lamp based on an array of micro-LEDs
`may be poWered by a standard high Voltage AC or DC poWer
`source. The indicator lamp has a loW poWer consumption. The
`micro-LEDs are serially connected on a substrate With the
`total device area and poWer consumption compatible With a
`standard DC loW Voltage LED. A plurality of indicator lamps
`may be connected together in parallel to present a string of
`indicator lamps.
`
`24 Claims, 2 Drawing Sheets
`
`'/- 10
`
`26
`
`28
`
`ITIFIIIIIlIIIIlIIIIlIIl'ITITI‘IT -'
`
`"llllllllllllllllIIIIIIIIJTIIIII
`
`14a
`
`IPR PAGE 1
`
`Acuity v. Lynk
`Acuity Ex.
`
`1011
`
`

`
`US 7,535,028 B2
`Page 2
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`U.S. PATENT DOCUMENTS
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`7,210,819
`7,213,942
`7,221,044
`2002/0006040
`2002/0043943
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`2004/0129946
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`2006/0180818
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`Bhat et al.
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`
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`
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`
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`JP
`
`2006/0208264 A1* 9/2006 Ryu et al. ................... .. 257/86
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`2004-006582
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`OTHER PUBLICATIONS
`Hongxing Jiang and Jingyu Lin, “On Display”, article from OE
`magazine Jul. 2001.
`H.X. Jiang and J .Y. Lin, “Advances in III-nitride micro-size light
`emitters”, article from The Advanced Semiconductor magazine, vol.
`14, No. 5.
`CH. Chen, H.J. Chang, Y.F. Chen, W.S. Fann, H.X. Jiang and J.Y.
`Lin, “Mechanism of photoluminescence in GaN/AI (0.2)Ga(0.8)N
`superlattices”, Applied Physics Letters, vol. 79, No. 23, Dec. 3, 2001.
`Dr. Jing Li, “III-Nitride Integrated Photonic Devices”, undated.
`“Kansas State Researchers Fabricate Blue Micro Light-Emitting
`Diodes, Paving Way for Microdisplays, Energy-Saving Lighting”,
`Ascribe The Public Interest NeWsWire, Sep. 27, 2001.
`S X Jin, J Li, J Y Lin and H X Jiang, InGaN/GaN Quantum Well
`Interconnected Microdisk Light Emitting Diodes; Applied Physics
`Letters, vol. 77, No. 20, p. 3236-3238, Nov. 13, 2000.
`Mair et al., Optical properties of GaN/AIGaN multiple quantum Well
`microdisks, Nov. 17, 1997, Appl. Phys, Lett. 76 (5) p. 631, American
`Institute of Physics.
`Zhaoyang Fan, Hongxing Jiang, Jingyu Lin; Related and Copending
`U.S. Appl. No. 11/144,982, ?led Jun. 3, 2005.
`Zhaoyang Fan; Related and Copending U.S. Appl. No. 11/340,296,
`Filed Jan. 26,2006.
`* cited by examiner
`
`IPR PAGE 2
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`

`
`US. Patent
`
`May 19, 2009
`
`Sheet 1 of2
`
`US 7,535,028 B2
`
`IPR PAGE 3
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`

`
`US. Patent
`
`May 19, 2009
`
`Sheet 2 of2
`
`US 7,535,028 B2
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`64
`
`66
`
`68
`
`62
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`70
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`% 4
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`74
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`72
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`110/120 VAC
`
`IPR PAGE 4
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`

`
`US 7,535,028 B2
`
`1
`MICRO-LED BASED HIGH VOLTAGE AC/DC
`INDICATOR LAMP
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`The present application claims the bene?t of provisional
`application Ser. No. 60/649,827, ?led Feb. 3, 2005, Which is
`hereby incorporated into the present application by reference.
`
`STATEMENT REGARDING FEDERALLY
`SPONSORED RESEARCH OR DEVELOPMENT
`
`This invention Was made in part With the support of the
`US. Government: the US. Government has certain rights in
`this invention as provided for by the terms of Grant DMI
`0450314 aWarded by the National Science Foundation.
`
`FIELD OF THE INVENTION
`
`The present invention relates to a light emitting diode
`(LED), and more particularly, to an indicator lamp, Which
`includes serially interconnected micro-siZe LEDs (Micro
`LEDs) integrated on a single chip. The resulting indicator
`lamp may be directly poWered by an AC voltage (i.e., 110/
`120V or 220/ 240V poWer grid) or a high DC voltage Without
`a poWer transformer.
`
`20
`
`25
`
`BACKGROUND OF THE INVENTION
`
`2
`enhance the light output compared With the standard broad
`area LED. Basically, these micro-LED arrays still Work under
`a loW DC voltage (several volts) With a typical current level of
`tens of mA.
`An individual micro-LED has a typical siZe of hundreds
`times smaller than the standard LED, and its area is even
`smaller than the contacts area of the standard LED, therefore,
`the device geometry layout design and fabrication process are
`considerably different from each other. The micro-LED array
`for high voltage AC/DC application is also different from that
`of the standard-siZe LED array. A need remains for a micro
`siZe light emitting diode array, Which may be poWered by
`standard high voltage AC/DC poWer and may be used to
`replace the conventional loW DC voltage indicator lamps.
`
`SUMMARY OF THE INVENTION
`
`The present invention provides a micro-LED array Which
`is serially interconnected With tWo outlet leads for connection
`With a high voltage AC/DC poWer supply. The array has a
`comparable total chip siZe andpoWer consumption to those of
`the conventional LED indicator lamps, so that the micro-LED
`array may be directly packaged in a housing used for a stan
`dard LED indicator lamp. The result is a high voltage AC/DC
`indicator lamp With the same or similar outside physical
`features as the standard LED indicator lamp. Depending on
`the detailed design, the supplied poWer to the high voltage
`AC/DC indictor lamp may be 12 volts, 24 volts, 36 volts, 48
`volts, and other DC voltages, or it may be anAC voltage such
`as 110/120 volts or 220/240 volts.
`A conventional LED indicator lamp may be replaced With
`an array of micro-LEDs connected in a serial mode, that is the
`p-contact (anode) of one micro-LED is connected With the
`n-contact (cathode) of its neighboring micro-LED, the result
`is that the applied voltage to the array equals to the sum of the
`voltage drop on each micro-LED. If each micro-LED Works
`under 3 volts, for example, then for a 120V poWer supply, the
`array Will have 40 serially connected micro-LEDs. Since the
`diode has current How and light emission only When the
`voltage drop betWeen its anode and cathode is positive, for an
`AC poWer supply, the above array Will only have light emis
`sion in the positive half cycle of the AC poWer. A second array
`may be used, Which is connected in parallel With the ?rst
`array, but this second array is arranged to have a reversed
`current ?oW direction, so that in each half cycle, there is one
`array emitting light. In this scheme, a conventional LED With
`a siZe 0.3 mm by 0.3 mm may be replaced by an array
`consisting of 80 micro-LEDs With a siZe of less than 25 um by
`25 um, considering that extra space is required for isolation
`and interconnection.
`The micro-LED array may be integrated on the same sub
`strate, and the isolation betWeen each micro-LED is accom
`plished through trench etching to remove the conductive
`materials doWn to the insulating substrate, or to an insulating
`layer sandWiched betWeen the micro-LED structure and the
`conductive or insulting substrate. This insulating layer may
`be epitaxially groWn on the substrate and its composition and
`thickness should be selected so that the subsequent micro
`LED material structure is thin enough (less than 2.5 um, for
`example), to ensure that the isolation trench etching and the
`metaliZation interconnection betWeen the neighboring micro
`LEDs may be easily accomplished. Another approach based
`on surface planariZation With spin-on polymers or deposited
`insulators is also presented.
`The integrated micro-LED array With a siZe comparable to
`the standard DC LED indicators, may have a similar package
`as the standard indictor lamp, and have similar poWer con
`
`30
`
`35
`
`40
`
`Tiny LED indicator lamps have been Widely used in elec
`tronics, toys, decorations and displays. These standard or
`conventional LEDs based on AlInGaN or AlInGaP have a
`typical chip area (or die siZe) of approximately 0.3 mmby 0.3
`mm. These LED lamps typically operate With a DC current of
`20 milliamps and a corresponding DC voltage betWeen 2
`volts and 4 volts, depending on the LED semiconductor mate
`rials. The standard indicator lamp With a T1 or T1-% package
`may have a maximum input poWer of about 0.1 Watt.
`Although the intrinsic loW voltage and DC current nature
`of the standard LED lamp makes it very convenient to be
`incorporated in electronics design, it may also be an incon
`venience in other applications. For example, in order to use
`these standard indicator lamps for Christmas tree decora
`tions, the LED-based light strings must employ parallel Wir
`ing of individual LEDs, a bulky step-doWn transformer and
`recti?er conversion scheme. LED light strings may also
`employ serial Wiring of individual LED lamps With the num
`ber of LED lamps dependant on the AC supply voltage. In the
`serially connected string, the number of LED lamps cannot
`easily be changed, and further, if one lamp fails and leads to
`an open circuit, the entire string Will not Work.
`A standard-siZe LED array may be integrated on the same
`substrate With a total device siZe from around 1 mm by 1 mm
`to 2 mm by 2 mm or even larger for 120 VAC supply. The
`55
`device runs under a current of approximately 20 mA or higher
`to achieve a high brightness for applications such as house
`hold lighting purpose. Such an AC-LED needs special pack
`aging and heat dissipation scheme because of the relatively
`large chip siZe and high thermal production, Which is not
`compatible With packaging requirements of loW poWer indi
`cator lamps. These poWer AC-LEDs are not suitable to
`replace the standard tiny LED indicator lamps.
`In US. Pat. No. 6,410,940, a micro-siZe LED (micro-LED)
`array is disclosed, Which is arranged in matrix format to be
`individually addressed for applications such as a micro-siZe
`display, or the array may be arranged in a parallel format to
`
`45
`
`50
`
`60
`
`65
`
`IPR PAGE 5
`
`

`
`US 7,535,028 B2
`
`3
`sumption. Since the input voltage is much higher, the indictor
`lamp in this invention runs under a current much smaller than
`the standard indicator lamp. For a 120 VAC design, the indi
`cator lamp may be directly run With the standard household
`poWer. Many indicator lamps may be connected in parallel to
`construct an LED string With high reliability.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an enlarged cross sectional vieW of a micro-LED
`based AC/DC indicator lamp With polymer planariZation.
`FIG. 2 is an enlarged sectional vieW of a micro-LED
`AC/DC indicator lamp With sloped side Walls.
`FIG. 3 is an enlarged cross sectional vieW of a micro-LED
`based AC/DC indicator lamp on a conductive substrate With
`an insulation epitaxial layer and a thin LED structure.
`FIG. 4 is an enlarged cross sectional vieW of a packaging of
`a micro-LED based AC/DC indicator lamp.
`FIG. 5 is an illustration of a parallel micro-LED based AC
`lamp string.
`
`DETAILED DESCRIPTION
`
`Referring to FIG. 1, an embodiment of a micro-LED of the
`present invention based on AlInGaN semiconductor materi
`als is generally indicated by reference numeral 10. Micro
`LED 10 may be groWn on an insulating sapphire substrate 12
`and include a buffer layer 14, n-type semiconductor layer 16,
`an activation region layer 18 and a p-type semiconductor
`layer 20. For 120 VAC applications, each micro-LED 10 may
`have dimensions of approximately 25 um by 25 um or similar
`siZe, formed by plasma etching doWn to the insulating sub
`strate 12. A p-contact (anode) 22 and an n-contact (cathode)
`24 are formed on the p-type layer 20 and n-type layer 16
`separately. A current spreading layer used for the standard
`broad area LED is generally not required for the micro-LED
`10 of the present invention because of the very small siZe of
`micro-LED, although its incorporation is also an option.
`The anode and cathode are formed by depositing different
`metals and then thermally annealing in a different tempera
`ture and ambient environment. For example, the anode is
`formed by a Ni and Au metal stack annealed in an oxygen
`containing environment, While the cathode is formed by a Ti
`and Al metal stack annealed in a nitrogen environment. To
`reduce the number of manufacture steps, a tunneling junction
`consisting of heavily doped n+ semiconductor and p+ semi
`conductor layers on the p-type semiconductor layer 20 may
`also be used. In this case, both the anode and cathode are
`formed in the same process step by the same Ti and Al metal
`stack on the n+ and n semiconductors respectively.
`An interconnection 26 betWeen the neighboring micro
`LEDs 10 may be accomplished in different Ways. Preferably,
`the interconnection 26 is accomplished by a surface pla
`nariZation, folloWed by metalliZation. A visible-light trans
`parent, but deep ultraviolet (DUV) photon de?nable polymer
`28 may be applied on the uneven surface of the micro-LEDs
`10 by spin-coating. Then With DUV photolithography, part of
`the polymer 28 is removed to achieve a quasi-?at surface With
`the p-type 22 and n-type 24 contacts exposed, folloWed With
`thermal curing to form hard polymide. With surface pla
`nariZation, the metal deposition for interconnection 26 may
`be easily accomplished. The polymer 28 also has the function
`to passivate the surface and etched side-Walls of the micro
`LEDs 10 to diminish the non-emission recombination rate
`and improve the device reliability. By selection of a polymer
`28 With a high refractive index, light extraction from the
`device 10 may be enhanced. A substitute material Which may
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`be used for the polymer is an insulating dielectric material
`such as different oxides or nitrides materials. For example,
`thick silicon oxides or silicon nitrides may be deposited into
`the deep trench betWeen micro-LEDs, so the trench can be
`?lled up to achieve a quasi-?at surface.
`Referring to FIG. 2, a micro-LED Which does not incorpo
`rate the surface planariZation step described hereinabove, is
`generally indicated by reference numeral 30. The isolation of
`the micro-LEDs 30 is accomplished by etching a trench 31 to
`the insulating substrate 12 With an quasi-isotropic plasma
`etch so that the sideWalls 32 have a slope With an angle,
`generally between 400 and 80°. With the sloped sideWalls, a
`thin layer of insulating dielectric materials 34 may be depos
`ited folloWed With the interconnection metal Wire 36. The
`insulating material 34, Which maybe silicon oxide, silicon
`nitride, or other insulators, isolates the metal Wire 36 from the
`semiconductor sideWalls 32, and passivates the dangling
`bonds on the sideWalls The sloped sideWalls 32 reduce the
`effective area of the micro-LED 30. HoWever, With the sloped
`sideWall pro?le, the insulating material 34 and the intercon
`necting metal Wire 36 can be conformably deposited With a
`uniform thickness on the ?at surface and on the sideWall;
`further, the sloped sideWalls 32 enhance the light extraction
`from the micro-LEDs 30. Because semiconductors typically
`have a large index of refraction, most of the generated light is
`trapped in the semiconductors forming a guided Wave, Which
`cannot escape. With the sloped pro?le, the guided light Waves
`have more opportunity to escape from the sideWalls 32 at the
`areas Without metal Wire 36. Note on the sideWalls, only a
`small potion is covered With the interconnection metal Wire
`36. The result is the micro-LED array 30 has more light
`e?iciency.
`Referring to FIG. 3, another embodiment of the micro
`LED of the present invention based onAlInGaN semiconduc
`tor materials is generally indicated by reference numeral 40.
`Micro-LED 40 may be groWn on different substrates 42 such
`as silicon carbide (SiC), silicon (Si), gallium nitride (GaN),
`aluminum nitride (AlN), gallium arsenide (GaAs), indium
`phosphide (InP) and sapphire (Al2O3), for example. Without
`the typical loW temperature buffer layer, the semiconductor
`groWth starts from high temperature groWn AlN With high
`resistivity. Other semiconductors such as AlGaN and AlIn
`GaN may also be used. This insulating layer gradually transits
`to the n-type GaN semiconductor layer 44 by changing
`AlGaN or AlInGaN alloy composition. Next the activation
`layer 46 is groWn folloWed by the p-type semiconductor layer
`48. A tunneling junction consisting of heavily doped n+ semi
`conductor and p+ semiconductor layers on the p-type semi
`conductor layer 48 may also be included, so the anode and
`cathode can be formed in one step.
`Without sacri?cing the ?nal device performance, the
`micro-LED structure layers 44, 46 and 48 (not include the
`insulating layer) are very thin, for example, less than 2.5 pm,
`instead of the typical thickness of more than 5 pm. The ben
`e?ts of this thin structure plus the resistive layer 42 are that
`conductive or semi-conductive substrates 50, such as SiC, Si,
`GaN, GaAs and InP, for example, may also be used for the
`high voltage AC/DC indicator lamp 40. Furthermore, an iso
`lation trench 52 may be only etched to the deposited insulat
`ing layer 42 With an quasi-isotropic etch, so the trench depth
`is shalloW and With an inclination slope, and a conformal
`interconnection metalliZation Wire 54 and a dielectric isola
`tion layer 56 applied to the sideWalls may be easily formed
`Without additional complex processing steps. The isolation
`layer 56 may consist of silicon oxide, silicon nitride, other
`oxide, nitride, or polymide, for example.
`
`IPR PAGE 6
`
`

`
`US 7,535,028 B2
`
`5
`Referring to FIG. 4, a device packaging 60 may include
`standard 3 mm, 5 mm, 10 mm, or other diameter lens sizes,
`known as T1, Tl-3A, and T3-% package respectively. These
`are the packages Which have been used for the standard LED
`indictor lamps. The device packaging 60 includes the epoxy
`lens or dome 62, a micro-LED array 64, a re?ector cup 66,
`Wire bonds 68 and 70, and tWo metal leads 72 and 74. The
`thermal dissipation of these packages 60 is through the tWo
`thin metal leads 72 and 74, leading to a high thermal resis
`tance and limited thermal dissipation ability. Such a package
`has a maximum input poWer of around 0.1 W, or a maximum
`current of less than around 1 mA for a 120VAC indictor lamp.
`Considering that the standard 0.3 mm><0.3 mm LED indicator
`lamp running under a current 20 mA With a current density of
`22 A/cm2, each micro-LED With an area of 25 um><25 um
`should run under a current density of 44 A/cm2, or a current
`0.3 mA. Even considering there are tWo micro-LED arrays 64
`connected in parallel and conducting in opposite directions,
`the total input poWer of the 120 VAC indicator lamp is still less
`than the maximum limitation, ensuring its reliability Without
`over heating.
`The indicator lamp 60 emits a light Wavelength depending
`on the bandgap energy of the semiconductor at the device
`active region. For example, if lnGaN is used at the active
`region, by changing indium composition in the lnGaN alloy
`to change the bandgap energy, it can emit a light covering
`ultra-violet (UV), blue and green Wavelength range. To
`achieve White light, phosphors may be used for color conver
`sion. For example, Yttrium Aluminate yelloW phosphor can
`absorb blue light and emit yelloW light. After Wire bonding, a
`phosphors slurry can be ?lled in the cup 66, folloWed With
`encapsulation 62. If micro-LED array 64 emits blue light and
`yelloW phosphor is incorporated, the combination of the
`transmitted blue light from micro-LED array and the yelloW
`light from the phosphor Will produce White color.
`Surface mounted packages may also be used for housing
`the micro-LED array. Furthermore, With a larger housing
`chamber, several micro-LED arrays With red, green, and blue
`colors fabricated from different semiconductors can be pack
`aged in the same housing. With the red, green, and blue color
`mixing, a high voltage AC/DC White emitter is achieved.
`The AC indicator lamp 60 may be easily used for indication
`and signaling purposes With a direct connection to the 110V/
`120V poWer supply. As an example, almost every machine or
`instrument poWered by electricity incorporates a conven
`tional LED beside (or inside) the poWer sWitch to indicate if
`the poWer is on. This standard indicator LED has to be driven
`by a loW DC voltage. If the AC indicator 60 is substituted for
`the conventional LED, it Will be directly driven by the 1 10V/
`120V poWer Without extra circuit. As another example for
`Christmas tree decorations, a parallel AC-LED lamp string
`may be constructed generally indicated by reference numeral
`80, as illustrated in FIG. 4. Since each lamp 60 runs With a
`current of approximately 1 mA, there is almost no limitation
`on the number of lamps connected in the string 80, and the
`string may be directly plugged into the house-holdAC poWer
`supply Without any transformer or recti?er. For safety rea
`sons, a fuse 82 may be serially connected With the lamp string
`80 for over-current protection in case some lamps are
`destroyed and form a short circuit. In that case, the shorted
`lamp may be removed, and the fuse 82 replaced With a neW
`fuse. If a bad lamp or a loose connection causes an open
`circuit, the parallel lamp string 80 Will still Work Without any
`replacement. To avoid the damage caused by the poWer surge
`in the poWer grid, a varistor (not shoWn) may be connected
`betWeen the terminals of the poWer supply. If a poWer surge
`
`40
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`45
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`30
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`35
`
`50
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`55
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`60
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`65
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`occurs, the varistor is trigged and the surge current Will by
`passed by the varistor to protect the indicator lamps 60.
`Although an lnGaAlN semiconductor emitter is used as
`examples in the invention description, it should be understood
`that a AC/DC light emitting device based on other semicon
`ductor materials such as GaAs, lnP, may be constructed.
`Depending on the bandgap energy of the semiconductor, the
`micro-LEDs may emit red, blue, green, yelloW or White light,
`for example. White light may be created by color mixing red,
`blue and green light or by Wavelength conversion With phos
`phor.
`It should be understood that While a certain form of this
`invention has been illustrated and described, it is not limited
`thereto except insofar as such limitations are included in the
`folloWing claims.
`Having thus described the invention, What is claimed as
`neW and desired to be secured by Letters Patent is:
`1. An AC/ DC lamp comprising:
`an integrated array of series connected micro-LEDs having
`a direction of current How and presenting positive and
`negative terminals, each of said micro-LEDs having an
`active region betWeen a p-type semiconductor and a
`n-type semiconductor,
`said array of series connected micro-LEDs groWn on a
`substrate,
`said terminals adapted to be connected across a poWer
`source to energiZe said array of series connected micro
`LEDs, and
`said array being included in a package formerly designed
`foruse for a standard-sized LED thus enabling said array
`to function as an indicator lamp.
`2. The AC/DC lamp as set forth in claim 1 Wherein said
`poWer source includes a poWer source selected from the
`group consisting of 12 volts DC, 24 volts DC, 36 volts DC, 48
`volts DC, 110 volts AC, 120 volts AC, 220 volts AC and 240
`volts AC.
`3. The AC/DC lamp as set forth in claim 1 Wherein said
`micro-LEDs are isolated from each other by etched trenches,
`and Wherein said trenches are ?lled With polymer, oxides,
`nitrides or other insulation materials to achieve a generally
`?at top surface.
`4. The AC/DC lamp as set forth in claim 1 Wherein said
`micro-LEDs include etched trenches and sideWalls, said side
`Walls coated With an insulation material.
`5. The AC/DC lamp as set forth in claim 4 Wherein said
`insulation material includes an insulation material selected
`from the group consisting of silicon oxide, silicon nitride,
`oxides, nitrides and polymides.
`6. The AC/DC lamp as set forth in claim 4 Wherein said
`sideWalls have a slope to enhance light extraction and con
`formal deposition of insulation material and interconnection
`metal Wire.
`7. The high voltage AC/DC lamp as set forth in claim 1
`further comprising a second array of series connected micro
`LEDs groWn on said substrate and connected in series or
`parallel to said array of series connected micro-LEDs.
`8. The high voltage AC/DC lamp as set forth in claim 1
`Wherein said substrate is an insulating substrate and includes
`a substrate material selected from the group consisting of
`sapphire, aluminum nitride, silicon carbide, silicon, gallium
`nitride, gallium arsenide and indium phosphide.
`9. The AC/DC lamp as set forth in claim 1 Wherein said
`substrate is a conducting or semi-conducting substrate and
`includes a substrate material selected from the group consist
`ing of silicon carbide, silicon, gallium nitride, gallium ars
`enide and indium phosphide.
`
`IPR PAGE 7
`
`

`
`US 7,535,028 B2
`
`7
`10. The AC/DC lamp as set forth in claim 1 further com
`prising an insulating layer between said substrate and said
`n-type semiconductor.
`11. The AC/ DC lamp as set forth in claim 10 Wherein said
`insulating layer selected from the group consisting of alumi
`num nitride, aluminum gallium nitride, and aluminum indium
`gallium nitride.
`12. The high AC/DC lamp as set forth in claim 10 further
`comprising a buffer layer betWeen said insulating layer and
`said substrate.
`13. The AC/ DC lamp as set forth in claim 12 Wherein said
`buffer layer has a thickness betWeen 0 and 10 um.
`14. The AC/DC lamp as set forth in claim 1 Wherein said
`micro-LEDs are based on semiconductors selected from the
`group consisting of AllnGaN, AllnGaP and AlGaAs.
`15. The AC/DC lamp as set forth in claim 1 further com
`prising a package for housing said array.
`16. The AC/ DC lamp as set forth in claim 15 Wherein said
`package includes a package selected from the group consist
`ing of T1, Tl-3A and T3-% having lens siZe diameters of 3
`mm, 5 mm, and 10 mm respectively.
`17. The AC/DC lamp as set forth in claim 16 further com
`prising a plurality of said indicator lamps connected in par
`allel.
`18. The AC/ DC lamp as set forth in claim 17 Wherein said
`indicator lamps emit the same or different colors.
`19. The AC/ DC lamp as set forth in claim 15 Wherein said
`package is a surface mount package.
`20. The AC/DC lamp as set forth in claim 1 Wherein said
`array of micro-LEDs emit White light by Wavelength conver
`sion With phosphor.
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`10
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`20
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`25
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`30
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`21. The AC/DC lamp as set forth in claim 1 Wherein said
`array of micro-LEDs emit White light by mixing red, blue and
`green light.
`22. The AC/DC lamp as set forth in claim 1 Wherein said
`array of micro-LEDs has a die siZe of less than approximately
`1 millimeter by l millimeter.
`23. An indicating lamp operable on a source of AC poWer,
`said lamp comprising:
`a ?rst serially-connected array of micro-LEDs groWn on a
`substrate;
`a second serially-connected array of micro-LEDs groWn
`on said a substrate;
`said ?rst array being connected in parallel With said second
`array;
`said second array being arranged such that it has a reversed
`current ?oW direction relative to said ?rst array so that
`When said lamp is operated using said source of AC
`poWer illumination is sustained regardless of current
`cycle; and
`said indicator lamp being ?ttable into a package formerly
`designed for use for a standard-sized LED.
`24. An AC lamp comprising:
`an integrated array of series connected micro-LEDs;
`said micro-LEDs being multiple times smaller than a con
`ventional 300 micron by 300 micron LED and thus
`causing said array to have a siZe Which enables a substi
`tution of said array in a conventional use of said conven
`tional 300 micron by 300 micron LED; and
`said array ?tted into a standard-sized LED indicator lamp
`package.
`
`IPR PAGE 8