AFFIDAVIT OF Pamela Stansbury
`
`STATE OF NEW YORK
`
`COUNTY OF TOMPKlNS
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`) ss.
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`Pamela Stansbury being of full age and duly sworn, deposes and says as follows:
`
`I. I am an employee of the Cornell University Library, and specifically Library Technical
`Services, located at Cornell University, Ithaca, New York 14853. I have personal
`knowledge of the facts set forth below.
`
`2. I am the Administrative Supervisor in Library Technical Services, which maintains
`bibliographical and processing information for many historical documents. I have held
`such position since 1996.
`
`3.
`
`Included in the Library's historical collection are various publications. As part of that
`collection, the Library maintains custody of an original issue of Applied physics letters,
`Volume 67, Number 13, 25 September 1995, which includes the paper High-power
`lnGaN single-quantum-well-structure blue and violet light-emitting diodes I by Shuji
`Nakamura, Masayuki Senoh, Naruhito Iwasa, and Shin-ichi Nagahama.
`
`4. Mr. Richard F. Moncrief requested information about Applied physics letters, Volume
`67, Number 13, 25 September 1995 - specifically when this item was first made
`publicly available by the Library. As best I can determine, the publication was publicly
`available at the Cornell University Library as September 27, 1995.
`
`ANDREA DENISE SMITH COLON
`NOTARY PUBUC·STATE OF NEW YORK
`Tompkins County
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`Registration #01 S~62762561
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`Commission Exp. 02/11/20 I
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`VIZIO 1022
`
`

`
`COII:N£LL UHIVf.'II:'!S::tTY L::tBII:AII::t£5
`S~l'ALS Ot:FT .
`l.l.0-8 OL::tH LISitAI\Y
`J:THACA , HY J.4S55- SS0.1
`
`SE.P2 7 1995
`
`VIZIO 1022
`
`

`
`APPLIED PHYSICS LETTERS
`
`Vol. 67, No. 13, 25 September 1995
`
`CODEN: APPLAB
`
`ISSN: 0003-6951
`
`OPTICS
`1797 Chirp of passively and actively mode-locked semiconductor lasers
`
`1800 Grating coupled multicolor quantum well infrared photodetectors
`
`1803 Pulsed laser deposition of BaTI03 thin films and their optical
`properties
`1806 Optical heterodyne detection of 60 GHz electro-optic modulation
`from polymer waveguide modulators
`
`1809 Picosecond spectroscopy of optically modulated high-speed laser
`diodes
`
`1812 Double layers of single domains formed by rapid thermal annealing
`of proton-exchanged LiTa03
`1815 Laser diode pumped 106 mW blue upconverslon fiber laser
`
`1818 New nonlinear optical crystal: Cesium lithium borate
`
`1821 Wavelength insensitive passive polarization converter fabricated by
`poled polymer waveguides
`1824 Physical modeling of pyrometric interferometry during molecular
`beam epitaxial growth of 111- V layered structures
`
`FLUIDS, PLASMAS, AND ELECTRICAL DISCHARGES
`1827 Generalized formula for the surface stiffness of fluid-saturated
`porous media containing parallel pore channels
`
`CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES
`1830 Characterization of structural defects in wurtzite GaN grown on 6H
`SiC using plasma-enhanced molecular beam epitaxy
`
`1833 Stress evolution during the growth of ultrathin layers of iron and
`iron silicide on Si(111)
`1836 Epitaxial electro-optical Sr,.Ba1 _,.Nb20 6 films by single-source
`plasma-enhanced metalorganlc chemical vapor deposition
`
`1839 Effects of hydrogen addition and growth-etch cycling on the
`oxy-acetylene torch deposition of homoepitaxial diamond
`1841 Electron spin resonance observations of excimer-laser-lnduced
`paramagnetic centers In tellurite glasses
`1844 Surface acoustic wave reflections from a proton exchanged dispersive
`dot array
`1847 Evidence of interstitial location of Er atoms implanted into silicon
`
`(Continued)
`
`M. Schell, J. Yu, M . Tsuchiya,
`T. Kamiya
`M. Z. lidrow, K. K. Choi, A. J. DeAnni.
`W. H. Chang, S . P. Svensson
`D. H. Kim, H. S . Kwok
`
`Wenshen Wang, Datong Chen,
`Harold R. Fetterman, Yongqiang Shi,
`William H. Steier, Larry R. Dalton,
`Pei-Ming D. Chow
`D. H. Sutter, H. Schneider,
`S. Weisser, J. D. Ralston,
`E. C. Larkins
`Cangsang Zhao, Reinhart Engelmann
`
`S. Sanders, R . G . Waarts,
`D. G. Mehuys, D. F. Welch
`Yusuke Mori, lkuo Kuroda,
`Satoshi NakajimaTakatomoSasaki,
`Sadao Nakai
`
`Min-Cheol Oh , Sang-Yung Shin,
`Woi-Yon Hwang, Jang-Joo Kim
`. H. P. Lee, E. Ranalli, X. Liu
`
`Peter B. Nagy, Adnan H. Nayfeh
`
`David J. Smith, D. Chandrasekhar,
`B. Sverdlov, A. Botchkarev,
`A. Salvador, H. Morko~
`D. Sander, A. Enders, J. Kirschner
`
`L. D. Zhu, J. Zhao, F. Wang,
`Peter E. Norris, G. D. Fogarty,
`B. Steiner, P. Lu, B . Kear, S. B. Kang,
`B. Gallais, M. Sinclair, D. Olmos,
`M. Cronin-Golomb
`R. A. Weimer, T. P. Thorpe.
`K. A. Snail, C. E. Merzbacher
`J. D. Prohaska, J . Li, J . S. Wang,
`A. H. Bartram
`Suneet Tuli, A. B. Bhattacharyya,
`D. Fournier
`A. Kozanecki, R. J . Wilson,
`B. J. Sealy, J . Kaczanowski,
`L. Nowicki
`
`VIZIO 1022
`
`

`
`1850 Relationship between self-organization and size of lnAs islands on
`lnP(001) grown by gas-source molecular beam epitaxy
`1853 Synthesis of oriented textured diamond films on silicon via hot
`filament chemical vapor deposition
`1856 High quality lnGaN films by atomic layer epitaxy
`
`SEMICONDUCTORS
`1859
`Improved thermal stability of AIGaAs-GaAs quantum well
`heterostructures using a " blocking" Zn diffusion to reduce column-Ill
`vacancies
`1862 Near-field optical beam induced current measurements on
`heterostructures
`1865 Growth of germanium-carbon alloys on silicon substrates by
`molecular beam epitaxy
`
`1868 High-power lnGaN single-quantum-well-structure blue and violet
`light-emitting diodes
`1871 The fabrication of quantum wire structures through application of
`CCI4 towards lateral growth rate control of GaAs on patterned GaAs
`substrates
`
`1874 Photoluminescence studies of single submonolayer lnAs structures
`grown on GaAs (001) matrix
`
`1877 High aspect ratio submicron silicon pillars f abricated by
`photoassisted electrochemical etching and oxidation
`1880 Effects of electron cyclotron resonance plasma thermal oxidation on
`the properties of polycrystalline silicon film
`1883 Measurement of the minority carrier mobility In the base of
`heterojunction bipolar transistors using a magnetotransport method
`1885 Comparative analysis of the optical quality of single
`ln0.1Ga0.9As/A10.33Ga0.67As quantum wells grown by molecular beam
`epitaxy on (100) and (311) GaAs substrates
`1888 Photoluminescence and microstructure of self-ordered grown SIGel
`Si quantum wires
`
`1891 Eu-doped CaF2 grown on 51(100) substrates by molecular beam
`epitaxy
`
`1894 Minority carrier lifetime improvement by gettering In Si1 _xGex
`
`1896 Reduction of recombination current in CdTe/CdS solar cells
`
`1899 The electronic structure and energy level alignment of porphyrin/
`metal interfaces studied by ultraviolet photoelectron spectroscopy
`
`1902 Temperature dependence of the etch rate and selectivity of silicon
`nitride over silicon dioxide In remote plasma NF~CI2
`1905 Band filling at low optical power density in semiconductor dots
`
`1908
`
`Investigation of high-field domain formation in tight-binding
`superlattices by capacitance-voltage measurements
`1911 High quality single and double two-dimensional electron gases
`grown by metalorganlc vapor phase epitaxy
`
`(Continued)
`
`A. Panchet, A. Le Corre, H. L'Haridon,
`B. Lambert, s. Salaun
`Qijin Chen, Jie Yang, Zhangda Lin
`
`K. S. Boutros, F. G. Mcintosh,
`J. C. Roberts, S. M. Bedair,
`E. L. Piner, N. A. EI-Masry
`
`M. R. Krames, A. D. Minervini,
`E. I. Chen, N. Holonyak, Jr.,
`J. E. Baker
`M. S. Unlu, B. B. Goldberg,
`W.D. He~og, D. Sun, E. Towe
`J. Kolodzey, P. A. O'Neil, S. Zhang,
`B. A. Orner, K. Roe, K. M. Unruh,
`C. P. Swann, M. M. Waite,
`S. lsmat Shah
`Shuji Nakamura, Masayuki Senoh,
`Naruhito lwasa, Shin-ichi Nagahama
`Yong Kim, Yang Keun Park,
`Moo-Sung Kim, Joon-Mo Kang,
`Seong-11 Kim, Seong-Min Hwang,
`Suk-Ki Min
`Wei Li, Zhanguo Wang, Jiben Liang,
`Bo Xu, Zhanping Zhu, Zhiliang Yuan,
`Jian Li
`H. W. Lau, G. J. Parker, R. Greet,
`M. Holling
`Jung-Yeal Lee, Chui-Hi Han,
`Choong-Ki Kim, Bok-Ki Kim
`Y. Setser, D. Ritter, G. Bahir,
`S. Cohen, J. Sperling
`0 . Brandt, K. Kanamoto, M. Tsugami,
`T. lsu, N. Tsukada
`
`A. Hartmann, C. Dieker, R. Loo,
`L. Vescan, H. Luth, U. Bangert
`X. M. Fang, T. Chatterjee,
`P. J. McCann, W. K. Liu, M. B. Santos,
`W. Shan, J. J. Song
`B. R. Losada, A. Moehlecke,
`R. Lagos, A. Luque
`D. M. Oman, K. M. Dugan,
`J. L. Killian, V. Ceekala,
`C. S. Ferekides, D. L. Morel
`S. Narioka, H. Ishii, D. Yoshimura,
`M. Sei, Y. Ouchi, K. Seki,
`S. Hasegawa, T. Miyazaki, Y. Harima,
`K. Yamashita
`J. Staffa, D. Hwang, B. Luther,
`J. Ruzyllo, R. Grant
`
`P. Castrillo, D. Hessman, M.-E. Pistol,
`S. Anand, N. Carlsson, W. Seifert,
`L. Samuelson
`Z. Y. Han, S. F. Yoon,
`K. Radhakrishnan, D. H. Zhang
`H. C. Chui, B. E. Hammons,
`J. A. Simmons, N. E. Hartt,
`M. E. Sherwin
`
`VIZIO 1022
`
`

`
`1914
`
`Intensity-dependent energy and line shape variation of donor(cid:173)
`acceptor-pair bands In ZnSe:N at different compensation levels
`
`SUPERCONDUCTORS
`1917 Extended function of a high-Tc transition edge bolometer on a
`micromachined Si membrane
`
`1920 Deposition of high quality YBa2Cu30 7 _ ,. films on ultrathin (12 ~tm
`thick) sapphire substrates for infrared detector applications
`
`1923 Generation of 24.0 Tat 4.2 K and 23.4 Tat 27 K with a high-temperature
`superconductor coil in a 22.54 T background field
`1926 Biomagnetlc measurements using low-noise integrated SQUID
`magnetometers operating in liquid nitrogen
`1929 Correlation of critical current and resistance fluctuations in bicrystal
`grain boundary Josephson junctions
`1932 Determination of pinning strength of YBa2Cu30 7 _ 6 from magnetic
`stiffness measurements
`
`1935 Disorder and synchronization in a Josephson junction plaquette
`
`MAGNETISM
`1938 History dependent domain structures In giant-magnetoresistive
`multilayers
`
`PAPERS IN OTHER FIELDS
`Ferroelectric phase transition temperatures of KTiOP04 crystals
`grown from self-fluxes
`
`1941
`
`COMMENTS
`1944 Comment on " Phase transformation of cobalt induced by ball
`milling" [Appl. Phys. Lett. 66, 308 (1995)]
`1945 Response to " Comment on 'Phase transformation of cobalt induced
`by ball milling'" [Appl. Phys. Lett. 67, 1944 (1995)]
`
`1947 CUMULATIVE AUTHOR INDEX
`
`P. Biiume, J . Gutowski, D. Wiesmann,
`R. Heitz, A. Hoffmann, E. Kurtz,
`D. Hommel, G. Landwehr
`
`H. Neff, J. Laukemper, G. Hefle,
`M. Burnus, T. J leidenblut,
`W. Michalke, E. Steinbeiss
`A. Pique, K. S. Harshavardhan,
`J. Moses, M. Mathur, T. Venkatesan,
`J. C. Brasunas, B Lakew
`K. Ohkura, K. Sate, M . . Ueyama,
`Jun Fujikami, Y. lwasa
`M. S. Dilorio, K-Y. Yang, S. Yoshizumi
`
`A. Marx, U. Fath, L. Alff, R. Gross
`
`Be ate Lehndorff,
`Hans-Gerd Kurschner,
`Bernhard Lucke
`A. S. Landsberg, Y. Braiman,
`K. Wiesenfeld
`
`H. T. Hardner, M. B. Weissman,
`S. S. P. Parkin
`
`N. Angert, M. Tseitlin, E. Yashchin,
`M. Roth
`
`G. Mazzone
`
`J. Y. Huang, Y. K. Wu , H. Q . Ye
`
`A publication of the American Institute of Physics, 500 Sunnyside Blvd., Woodbury, NY 11797-2999
`
`VIZIO 1022
`
`

`
`APPLIED
`PHYSICS
`LETIERS
`
`CODEN: APPLAB
`ISSN: 0003-6951
`
`Editor
`Nghi Q. Lam
`Argonne National Laboratory
`Argonne, IL
`
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`
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`at Argonne National Laboratory
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`Alan A. Krauss
`Jules Routbort
`David S. Kupperman
`Linda Young
`F. Paul Mooring
`
`Editorial Board
`Term ending 31 December 1995
`Ulrich Giisele (Max Planck lnst., Halle, Germany)
`William L. Johnson (Caltech, Pasadena, CA)
`William F. Krupke (Lawrence Livermore Lab, CA)
`
`Term ending 31 December 1996
`Gene F. Dresselhaus (MIT, Cambridge, MA)
`Allen M. Goldman (Univ. Minnesota, Minneapolis, MN)
`Klaus H. Ploeg (Paul Drude lnst., Berlin, Germany)
`Robert Sinclair (Stanford Univ., Stanford, CA)
`
`Term ending 31 December 1997
`Federico Capasso (AT&T Bell Labs, Murray Hilt, NJ)
`Esther M. Conwell (Xerox, Rochester, NY)
`C. Y. Fong (Univ. of California, Davis, CA)
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`VIZIO 1022
`
`

`
`High-power lnGaN single-quantum-well-structure blue and violet
`light-emitting diodes
`Shuji Nakamura,al Masayuki Senoh, Naruhito lwasa, and Shin-ichi Nagahama
`Depurmumt of Res~arch arul Dni!lopml'fll, N1chin Ch~mical lndustrtes. Lid., 491 Oka, Kaminaka, '\nan.
`TokushiuUI 774, Japan
`
`(Received 28 March 1995; accepted for publication J I July t99:n
`
`High-power blue and violet light-emitting diode~ (LEOs) ba!>ed on Ill- V nitride~ were grown by
`metalorganic chemical vapor depOSition on ~apphire :;ubstrate::.. As an active layer, the LnGaN
`single-quantum-well-structure was used. The violet LEDs produced 5.6 mW at 20 mA. with a ~harp
`peak of light output at 405 nm, and exhibited an external quantum efficiency of 9.2%. The blue
`LEOs produced 4.8 mW at 20 mA and sharply peaked at 450 nm, corresponding to an external
`quantum efficiency of 8.7%. These values of the output power and the quantum efficiencies arc the
`highest ever reported for violet and blue LEOs. ~ 1995 American lnstitme of Pln·sics.
`
`Much research has been conducted on h1gh-bnghtne s
`blue light-emitting diodes (LEDs) and laser diode~ (LD~) for
`U'>e in full-color di plays. fult-.color indica10rs. and light
`'>Ources for lamp with the characteri~t1cs of high effic1ency.
`high reliability. and high speed. For 1hese purpo es. II- VI
`materials uch as ZnSe} SiC,2 and 11£- V nitride semicon(cid:173)
`ductors such as GaN1 have been inve~tigated intensively for
`a lo ng time. However, it ha~ been impossible to obtain high(cid:173)
`brightness blue LED::. with brightness over I cd. As II - VI
`based materials. ZnMgSSe-, ZnSSe-, and ZnCdSe-based ma(cid:173)
`teriab have been intensively studied for blue and green light(cid:173)
`emining devices, and much progress ha~ been achieved re(cid:173)
`cently on green LED-; and LOs. The recent situation
`regarding performance of ll- VI green LEOs is that the out(cid:173)
`put power is 1.3 mW at 10 rnA and that the peak wa\'elength
`is 512 nm.4 When the peak wavelength ~honens to the blue
`region, the output power decreases dramallcally to about O.J
`mW at 489 nm.'' The lifetime of 0 - YI-based light-emitting
`devices is st1ll short. which prevents the commercialization
`of ll - VI-based devicec; at present. SiC i!> another w1.,e band(cid:173)
`gap material for blue LEOs. Current output power of SiC
`blue LEOs is only between 10 and 20 J.LW because it is an
`indirect band-gap material.1
`On the other hand. there are no suitahle wbstrates for
`Ill- Y nitride growth without sapphire considering its high
`growth temperature and the cost of the substrate although the
`sapphire has a large lattice mismatch between GaN and sap(cid:173)
`phire. Despite thi large lattice mismatch. recent research on
`Ill- V nitrides has paved the way for the renli:zation of high(cid:173)
`qua lit) crystals of AIGaN and InGaN, and p-type conduction
`in AIGa.N.5
`8 Moreover. the hole-compensation mechanism
`-
`of p -type AIGaN has been elucidated.9 High-power blue and
`blue-green LED with an output power over I mW have
`been achieved by u ing these techniques and are now com(cid:173)
`11 Although
`mercJally available. 10
`these
`lnGaN/AlGaN
`·
`double-heterostructure (DH) LED produce a high-power
`light output in the blue and blue-green region:-.. they have a
`broad emission spectrum [full w1dth at half-maximum
`(FWHM)=70 nm] with the light output ranging from the
`
`"'Electronoc nuliJ· \huji@'nich•a.co.jp
`
`violet to the yellow-orange ~pectral region. Thi<> broad spec(cid:173)
`trum. which result:-. from the intentional introduction of Zn
`into the lnGaN active region of the device to produce a deep(cid:173)
`level emisl-ion peaking at 450 nm, makes the output appear
`whitish-blue. when the LED is \oiewed with the human eye.
`Therefore, blue LEOs. wh1ch produce a sharp blue emission
`at 450 nm with a narrow FWHM. have been desired for
`application to full-color LED displays. For this purpose, vio(cid:173)
`let LEOs with a narrow spectrum (FWHM = I 0 nm) at a peak
`wavelength of 400 nm originating from the band-to-band
`emission of JnGaN were reported. 12 However, the output
`power of these violet LEOs was only about 1 mW, probably
`due to the fonnation of mi~fit dislocation in the thick lnGaN
`active layer (about 1000 AJ by the stress introduced into the
`lnGaN active layer due to lattice mismatch. and the differ(cid:173)
`e nce in thennal expansion coefficients between the lnGaN
`active layer and AIGaN cladding layers. When the thickness
`of the lnGaN active layer become~ mall, the elastic strain b
`not relieved by the formation of misfit dislocation and that
`the crystal quality of the lnGaN acuve layer improves. We
`reponed the high-quality lnGaN multiquantum-well stmcture
`(MQW) with the 30 A well and 30 A barrier layers.•~ Here,
`we describe the single quantum-well stmcture (SQW) blue
`LEOs which have a thin lnGaN active layer (about 20 A) in
`order to obtain high-power blue emission with a narrow
`emission spectrum.
`Ill- V nitride films were grown by the two-flow mernlor(cid:173)
`ganic chemical vapor depos ition (MOCVO) method. Detail!>
`of the two-How MOCVD are described in other papers. 14
`The growth was conducted at atmo~pheric pressure. Sapphire
`with (000 I) orientation (c face), which had a 2 in. diameter.
`was u~ed as a sub trate. The growth conditions of each layer
`are described in other paper..: 0
`•11 In comparison with prc\oJ(cid:173)
`ous LnGaN/AIGaN DH LEOs, the major difference is that the
`lnGaN active layer become!. u th111 undoped lnGa
`layer.
`The blue LED device !.tructures (Fig. I) consists of a
`300 A GaN buffer layer grown at a low temperature
`(550 °C), a 4 ,um thick layer of 11-1ype GaN:Si, a 1000 A
`thicklayer of n-type Al0 JGII(17N:Si, a 500 A thick layer
`of 11-type InomG3o.9sN:Si. a 20 A thick active layer of un(cid:173)
`lno.2Gao 8N. a 1000 A thick
`doped
`layer of p-type
`Alo.3GUo.7N:Mg. and a 0.5 ,um thick layer of p-type GaN:Mg.
`
`1868
`
`Appl. Phys. Lett. 67 {13), 25 September 1995
`
`0003-6951/95/67(13)/186813/$6.00
`
`C 1995 American Institute of PhysJcs
`
`VIZIO 1022
`
`

`
`--
`I
`
`p·electrode
`
`p-GaN
`p·AI0,,GauN
`lnuGauN
`n·ln 0.0,Gao...N
`n·AiuGa1,7N
`o-GaN
`GaN buffer layer
`
`- ,
`
`n~e
`
`14
`
`12
`
`10
`~
`_§. 8
`
`.. .. !1:
`;; ... ;;
`
`0
`Ct.
`
`0
`
`6
`
`4
`
`2
`
`Forward Current (rnA)
`
`FIG. 3. The ou1put power of (a) SQW violet LED, (b) SQW blue LED. and
`(c) DH blue LED as a function of the forward currenL
`
`meV. In order to explain this band-gap narrowing of the
`ln0.2Gao.8N active layer, the quantum size effects, the exciton
`effects (Coulomb effects correlated to the electron-hole pair)
`of the active layer, and the strained effects by the mismatch
`of the lattice and the difference in thermal expansion coeffi(cid:173)
`cients between well layer and banier layers must be consid(cid:173)
`ered. Among these effects. the tensile stress in the active
`layer caused by the thermal expansion coefficient difference
`between well layer and barrier layers is probably responsible
`for the band-gap narrowing of the InGaN SQW structure.
`The output power of the SQW LEOs and the DH blue
`LEOs is shown as a function of the forward current under de
`in Fig. 3. The output power of the SQW LEOs and that of the
`DH LEOs slightly increases sublinearly up to 40 mA as a
`function of the forward current. Above 60 mA. the output
`power almost saturates. probably due to the generation of
`heat. The output power of the SQW violet LEOs is 2.8 mW
`at 10 mA, and 5.6 mW at 20 mA. which is about twice as
`high as that of the DH blue LEDs. The external quantum
`efficiency is 9.2% at 20 mA. The output power of SQW blue
`LEDs with a peak wavelength of 450 nm is 4.8 mW at 20
`rnA and the external quantum efficiency is 8.7%.
`A typical example of the/- V characterisucs of the SQW
`blue LEOs is shown in Fig. 4. The forward voltage is 3.1 V
`
`Y: SmA/div.
`
`Sapphire substrate
`
`_
`
`FIG. I. The structure of SQW blue LED.
`
`The active region forms a SQW structure consisting of a 20
`A ln0.2Gao.8N well layer sandwiched by 500 A 1Hype
`ln0.02Gao 98N and 1000 A p-type A10.3Gao.7N barrier layers.
`ln violet LEOs, the active layer is ln0.09Gao.9N.
`Fabrication of LED chips was accomplished as follows.
`The surface of the p-type GaN layer was partially etched
`until then-type GaN layer was exposed. Next, a Ni/Au con(cid:173)
`tact was evaporated onto the p-type GaN layer and a Til AI
`contact onto the n-type GaN layer. The wafer was cut into a
`rectangular shape (350 p.m X 350 ,um). These chips were set
`on the lead frame, and were then molded. The characteristics
`of LEOs were measured under direct current (dc)-biased con(cid:173)
`ditions at room t~mperature.
`Figure 2 shows the electroluminescences (EL) of the
`SQW blue LEOs in comparison with the previous Zn-doped
`lnGaN/AIGaN DH blue LEDs at forward current of 20 rnA
`The peak wavelengths of both LEDs are 450 nm. The
`FWHM of the EL spectrum of the SQW blue LED1:. is about
`25 nm. while that of DH LEOs is about 70 nm. The peak
`wavelength and the FWHM of SQW LEOs are almost con(cid:173)
`stant when the forward current is increased to I 00 mA. On
`the other hand. the peak wavelength of DH LEDs becomes
`shorter with increasing forward current and a band-to-band
`emission (around 385 nm) appears under a high-current in(cid:173)
`jection condition. 10•11 In the SQW blue LEDs, the active
`layer is an ln0_2Gao.8N whose band-edge emission wave(cid:173)
`length is 420 nm under the stress-free. 12 On the other hand,
`the emission peak wavelength of SQW blue LEOs is 450 nm.
`The energy difference between the peak wavelength of the
`ELand the stress-free band-gap energy is approximately 190
`
`R.T.
`lf::20mA
`
`100
`~ ·;:
`=
`.0
`$
`-~so
`c
`" !
`
`350
`
`400
`
`450
`Wavelength (nm)
`
`600
`
`650
`
`FIG. 2. Electroluminc,cencc spoclra of (a) SQW blue LED and (b) DH blue
`LED at a forward currem of 20 mA.
`
`FIG. 4. Typical I-V characteriMics of SQW blue LED.
`
`X: lV/div.
`
`Appl. Phys. Lett., Vol. 67, No. 13. 25 September 1995
`
`Nakamura et al.
`
`1869
`
`VIZIO 1022
`
`

`
`at 20 rnA. This forward voltage is the lowest value ever
`reported for ill- V nitride LEDs.
`In ummary, high-power lnGaN SQW blue and violet
`LEOs were fabricated. The output power of the violet LEOs
`was 5.8 mW and the external quantum efficiency was as high
`as 9.2% at a forward current of 20 rnA at room temperature.
`The peak wavelength and the FWHM were 405 and 20 nm.
`respectively, and those of blue LEOs were 450 and 25 nm,
`respective ly. Such LED performances of quantum well struc(cid:173)
`tures will pave the way for the realization of blue LOs based
`on m- V nitride materials in the near future.
`
`1 W. Xic, D. C. Grillo, R. L. Gunshor, M. Kobayashi. H. Jeon, J. Ding, A. V.
`Nurmtkko. G. C. Hua. and N. Otsuka. Appl. Phys. Leu. 60, 1999 (1992).
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`Series ~o. 137 (American ln•titute of Ph)sics. Woodbury. NY. 1994), p.
`515.
`
`3 J. I. Pankove, E. A. Miller. and J. E. Berkeyheiser, RCA Re~. 32. 283
`(197 1).
`4 0 . E. Eason, z. Yu. W. C. Hughe'. W. H. Roland, C. Boney, J. W. Cook.
`Jr .. J. F. Schetzina, G. Cantwell. and W. C. Harasch. Appl. Phy~. Len. 66.
`11 5 (1995).
`' S. Strite and H. Morlo.~. J. Vac. Sci. Techno! B JO, t237 (1992).
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`1258 (1992).
`10 S. Nakamura. T Mukai. and M. Senoh, Appl. Phys. Leu. 64. 1687 ( 1994)
`11 5 . NakamurJ, T. Mukai. and M. Scnoh, J. Appl. Phys. 76. 8 1R9 ( 1994)
`12 S. Nakamura. Mlcroclectron J. 25, 65 1 (1994).
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`PhY'· 74.3911 (1993).
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`
`1870
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`Appl. Phys. Lett., Vol. 67, No. 13, 25 Se ptember 1995
`
`Nakamura et a/
`
`VIZIO 1022