. APPLIED
`PHYSICS
`LETTERS
`
`
`
`
`28 MMIBII 1994
`
`VOLUME 54 NUMBER”
`
`
`
`AMERICAN
`INSTITUTE
`@PHYSICS
`
`
`
`
`0003-6951(19940328)6/o:13;1-X
`
`NEWSPAPER
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`

`

`APPLIED PHYSICS lEnERS
`
`Vol. 64, No. 13, 28 March 1994
`
`CODEN: APPLAB
`
`ISSN: 0003-6951
`
`OPTICS
`1601
`
`Experimental study of a waveguide free-electron laser using the
`coherent synchrotron radiation emitted from electron b i^ h es
`
`I
`1604 Electrochromism of sputtered fluorinated titanium oxibe“‘thJn 4 Mtis
`
`1607
`
`1610
`
`Improved characteristics of a Cherenkov laser loaded. With a Kerr-lik^
`medium
`Inherent bandwidth limits in semiconductor lasers due to distributed
`microwave effects
`
`1613 Jitter improvement in mark edge recording for phase change optical
`disks with optical phase encoding
`1615 Electron paramagnetic resonance study of a native acceptor in
`as-grown ZnGeP2
`
`1618 Micrometer scale visualization of thermal waves by photoreflectance
`microscopy
`
`ACOUSTICS
`1620 Acoustic phase conjugation in highly nonlinear PZT piezoelectric
`ceramics
`
`FLUIDS, PLASMAS, AND ELECTRICAL DISCHARGES
`1623 Electron acceleration resonant with sheath motion in a low-pressure
`radio frequency discharge
`1626 Electron collision cross sections of boron trichloride
`1629 Fluid dynamics and dust growth in plasma enhanced chemical vapor
`deposition
`1632 Materials characterization with the acoustic microscope
`
`CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES
`1635 Diffraction limited dry etching of GaAs at X.=130 nm
`
`1638 Nucleation of boron nitride on cubic boron nitride microcrystallites
`using chemical vapor deposition
`1641 Diffusion length of Ga adatoms on GaAs ( i l l ) surface in the
`reconstruction growth regime
`^ [ ^ 9 X
`(Ba-t-Sr)/Ti ratio dependence of the dielectric properties for
`(Bao.sSro.5)Ti0 3 thin films prepared by ion beam sputtering
`1647 Growth of SiC using hexamethyidisilane in a hydrogen-poor ambient
`
`1644
`
`Makoto Asakawa, Naoki Sakamoto,
`Naoki Inoue, Tatsuya Yamamoto,
`Kunioki Mima, Sadao Nakai,
`Jizhong Chen, Masayuki Fujita,
`Kazuo Imasaki, Chiyoe Yamanaka,
`TjAlatsuo Agari, Takashi Asakuma,
`cwobuhisa Ohigashi,
`■-jyoshiaki Tsunawaki
`fA. Gutarra, A. Azens, B. Stjerna,
`' C. G. Granqvist
`T. Shiozawa, T. Sato, K. Horinouchi
`
`Daniel A. Tauber, Ralph Spickermann,
`Radhakrishnan Nagarajan,
`Thomas Reynolds,
`Archie L. Holmes, Jr., John E. Bowers
`Tatsunori Ide, Mitsuya Okada
`
`M. H. Rakowsky, W. K. Kuhn,
`W. J. Lauderdale, L. E. Halliburton,
`G. J. Edwards, M. P. Scripsick,
`P. G. Schunemann, T. M. Poliak,
`M. C. Ohmer, F. K. Hopkins
`L. Pettier
`
`M. Ohno, K. Takagi
`
`Yoshihiro Okuno, Yasunori Ohtsu,
`Hiroharu Fujita
`Rajesh Nagpal, Alan Garscadden
`Peter Haaland, Sokol Ibrani,
`Hao Jiang
`S. Hirsekorn, S. Pangraz
`
`B. Li, I. Twesten, H.-P. Krause,
`N. Schwenter
`Hidetoshi Saitoh, Takeshi Hirose,
`Tomoo Ohtsuka, Yukio Ichinose
`K. Yang, L. J. Schowalter, T. Thundat
`
`Shintaro Yamamichi, Hisato Yabuta,
`Toshiyuki Sakuma, Yoichi Miyasaka
`N. Nordeii, S. Nishino, J.-W. Yang,
`C. Jacob, P. Pirouz
`
`(C o n tin u e d )
`
`
`
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`

`

`1650 Crystal structure and magnetic properties of LaCo^s.^Si^ compounds
`
`1653 Nanoindentation hardness measurements using atomic force
`microscopy
`1656 New approach for synthesizing Ge quantum crystailites embedded in
`a-SiNx films
`
`SEMICONDUCTORS
`1659 New microfabrication technique by synchrotron radiation-excited
`etching: Use of noncontact mask on a submicrometer scaie
`
`1662 Hydrodynamic approach to noise spectra in unipoiar semiconductor
`structures
`Photoiuminescence of InAs/AiSb single quantum wells
`
`1665
`
`1668
`
`1670
`1673
`
`1681
`
`Simple Diophantine test for the validity of conventional deep level
`transient spectroscopy
`{H,P}"^ transitions: A new iook at donor-hydrogen pairs in Si
`Low temperature electron cyclotron resonance plasma etching of
`GaAs, AIGaAs, and GaSb in Ci2/Ar
`1676 Opticai anisotropy and spin polarization in ordered GainP
`1679 Kinetic pattern formation of Gd-silicide fiims in iaterai growth
`geometry
`Cyciotron effective mass of hoies in Si^ .^Gex/Si quantum wells:
`Strain and nonparabolicity effects
`1684 Detection of hydrogen-piasma-induced defects in Si by positron
`annihiiation
`1687 Candeia-class high-brightness inGaN/AiGaN double-heterostructure
`blue-light-emitting diodes
`Temperature-dependent study of spin-dependent recombination at
`silicon dangling bonds
`1693 High efficiency chemical etchant for the formation of luminescent
`porous silicon
`
`1690
`
`1696 Reduced phosphorus loss from InP surface during hydrogen plasma
`treatment
`Fabrication of three-terminal resonant tunneling devices in
`silicon-based material
`
`1699
`
`1702
`
`1705
`
`Si/Ge/S multilayer passivation of GaAs(IOO) for
`metal-insulator-semiconductor capacitors
`
`Picosecond carrier escape by resonant tunneling In pseudomorphic
`InGaAs/GaAsP quantum well modulators
`
`1708
`
`1711
`
`1714
`
`Strained ln0 .4 0AI0.6 0As window layers for indium phosphide solar
`cells
`Negative differential resistance at room temperature in <$^oped
`diodes grown by Si-molecular beam epitaxy
`Electronic mobility gap structure and deep defects in amorphous
`silicon-germanium alloys
`Pressure dependence of deep level transitions in AgGaSe2
`1717
`1720 Dynamics of beam defocusing and induced absorption in CdZnTe
`alloys
`
`G. H. Rao, J. K. Liang, Y. L. Zhang,
`X. R. Cheng, W. H. Tang
`Bharat Bhushan, Vilas N. Koinkar
`
`X.-X. Qu, K.-J. Chen, X.-F. Huang,
`Z.-F. Li, D. Feng
`
`Shingo Terakado, Takashi Goto,
`Masayoshi Ogura, Kazuhiro Kaneda,
`Osamu Kitamura, Shigeo Suzuki,
`Kenichiro Tanaka
`V. Gruzinskis, E. Starikov,
`P. Shiktorov, L. Reggiani, L. Varani
`F Fuchs, J. Schmitz, H. Obloh,
`J. D. Ralston, P. KoidI
`Dobri Batovski, Chavdar Hardalov
`
`S. K. Estreicher, R. Jones
`S. J. Pearton, F. Ren, C. R. Abernathy
`
`Su-Huai Wei, Alex Zunger
`G. Molnar, G. Peto, Z. E. Horvath,
`E. Zsoldos
`J.-P. Cheng, V. P. Kesan,
`D. A. Grutzmacher, T. 0. Sedgwick
`P. Asoka-Kumar, H. J. Stein,
`K. G. Lynn
`Shuji Nakamura, Takashi Mukai,
`Masayuki Senoh
`D. Vuillaume, D. Deresmes,
`D. Stievenard
`Michael T. Kelly,
`Jonathan K. M. Chun,
`Andrew B. Bocarsly
`Sathya Balasubramanian,
`Vikram Kumar, N. Balasubramanian
`A. Zaslavsky, K. R. Milkove, Y. H. Lee,
`K. K. Chan, F. Stern,
`D. A. Grutzmacher, S. A. Rishton,
`C. Stanis, T. 0. Sedgwick
`Z. H. Lu, D. Landheer,
`J.-M. Baribeau, L J. Huang,
`W. W. Lau
`N. M. Froberg, A. M. Johnson,
`K. W. Goossen, J. E. Cunningham,
`M. B. Santos, W. Y, Jan, T. H. Wood,
`C. A. Burrus, Jr.
`R. K. Jain, G. A. Landis, D. M. Wilt,
`D. J. Flood
`M. R. Sardela, Jr., H. H. Radamson,
`G. V. Hansson
`Thomas Unold, J. David Cohen,
`Charles M. Fortmann
`In-Hwan Choi, Peter Y. Yu
`B. Honerlage, D. Ohimann,
`M. Benhmida, R. Levy, J. B. Grun
`
`(C o n tin u e d )
`
`
`
`TCL 1024, Page 4TCL 1024, Page 4
`
`

`

`1723
`
`Impurity-mediated growth and characterization of thin pseudomorphic
`germanium layers in silicon
`
`H. J. Osten, E. Bugiei, B. Dietrich,
`W. Kissinger
`
`SUPERCONDUCTORS
`1726 Temperature dependence of the electron energy gap of high T q
`superconductors studied by work function spectroscopy
`1729 Direct observation of Josephson seif-radiation in Bi2Sr2Ca2Cu3 0 ^
`break junctions above 77 K
`1732 Determination of density of trap states at Y2 0 3 -stabilized Zr02/Si
`interface of YBa2Cu3 0 7 _^/Y2 0 3 -stabilized Zr0 2 /Si capacitors
`1735 Fast growth of Bi2Sr2 Ca2Cu3 0 io+x and Bi2Sr2CaCu20s+x thin crystals
`at the surface of KCI fluxes
`
`PAPERS IN OTHER FIELDS
`1738 Tapping mode atomic force microscopy in liquids
`
`1741 Vanishing Freedericksz transition threshold voltage in a chiral
`nematic liquid crystal
`
`1744 CUMULATIVE AUTHOR INDEX
`
`S. Westermeyr, R. Muller, J. Scholtes,
`H. Oechsner
`Kiejin Lee, lenari Iguchi,
`Takeshi Hikata, Ken-ichi Sato
`Jianmin Qiao, Kuohsu Wang,
`Cary Y. Yang
`G. Balestrino, E. Milani, A. Paoletti,
`A. Tebano, Y H. Wang, A. Ruosi,
`R. Vaglio, M. Valentino, P. Paroli
`
`P. K. Hansma, J. P. Cleveland,
`M. Radmacher, D. A. Walters,
`P. E. Hillner, M. Bezanilla, M. Fritz,
`D. Vie, H. G. Hansma, C. B. Prater,
`J. Massie, L. Fukunaga, J. Gurley,
`V. Elings
`Karl A. Crandall, Michael R. Fisch,
`Rolfe G. Petschek,
`Charles Rosenblatt
`
`A publication of the American Institute of Physics, 500 Sunnyside Blvd., Woodbury, NY 11797-2999
`
`
`TCL 1024, Page 5TCL 1024, Page 5
`
`

`

`Candela-class high-brightness InGaN/AIGaN double-heterostructure
`blue-light-emitting diodes
`Shuji Nakamura, Takashi Mukai, and Masayuki Senoh
`Department of Research and Development, Nichia Chemical Industries, Ltd., 491 Oka, Kaminaka, Anan,
`Tokushima 774, Japan
`(Received 2 December 1993; accepted for publication 5 January 1994)
`
`(D H) blue-light-emitting
`InGaN/AIGaN double-heterostructure
`Candela-class high-brightness
`diodes (LEDs) with the luminous intensity over 1 cd were fabricated. As an active layer, a Zn-doped
`InGaN layer was used for the D H LEDs. The typical output power was 1500 /uW and the external
`quantum efficiency was as high as 2.7% at a forward current of 20 mA at room temperature. The
`peak wavelength and the full width at half-maximum of the electroluminescence were 450 and 70
`nm, respectively. This value of luminous Intensity was the highest ever reported for blue LEDs.
`
`Recently, there has been much progress in wide-band-
`gap II-V I compound semiconductor research, in which the
`first blue-green' and blue injection laser diodes (LDs)^ as
`well as high-efficiency blue-light-emitting diodes (LEDs)^
`have been demonstrated. For the application to blue light-
`emitting devices, there are promising materials, such as
`wide-band-gap nitride semiconductors, which have great
`physical hardness, extremely large heterojunction offsets,
`high thermal conductivity, and high melting temperature.'* In
`this area, there has recently been great progress in the crystal
`quality, p-type control, and growth method of GaN films.^ '’
`For practical applications to short-wavelength optical de­
`vices, such as LDs, a double heterostructure is indispensable
`for III-V nitrides. The ternary III-V semiconductor com­
`pound, InGaN, is one candidate as the active layer for the
`blue emission because its band gap varies from 1.95 to 3.40
`eV, depending on the indium mole fraction. Up to now, not
`much research has been performed on InGaN growth.’ ”^ Re­
`cently, relatively high-quality InGaN films were obtained by
`Yoshimoto et al.,^ at a high growth temperature (800 °C) and
`a high indium source flow rate ratio. The present authors
`discovered that the crystal quality of InGaN films grown
`on GaN films was greatly improved in comparison with that
`on a sapphire substrate, and the band-edge (BE) emission
`of InGaN became much stronger
`in photoluminescence
`(PL) measurements. Thus, the first successful InGaN/GaN
`D H blue LEDs were fabricated using the above-mentioned
`InGaN films." On the other hand, Zn doping into GaN has
`been intensively investigated to obtain blue emission centers
`for the application to blue LEDs by many researchers be­
`cause strong blue emissions have been obtained by Zn dop­
`ing into GaN.*^“*^ However, there are no reports on Zn dop­
`ing into InGaN. In this letter, the InGaN/AIGaN D H blue
`LED which has a Zn-doped InGaN layer as an active layer is
`described for the first time.
`InGaN films were grown by the two-flow metalorganic
`chemical vapor deposition (M O C V D ) method. Details of the
`two-flow M O C V D are described in other a r t i c l e s . T h e
`growth was conducted at atmospheric pressure. Sapphire
`with (0001) orientation (C face), two inches in diameter, was
`used as a substrate. Trimethylgallium (TM G ), trimethylalu-
`minum (TM A ), trimethylindium (T M I), monosilane (SiH4),
`
`(Cp2Mg), diethylzinc
`bis-cyclopentadienyl magnesium
`(DEZ), and ammonia (N H 3) were used as Ga, Al, In, Si, Mg,
`Zn, and N sources, respectively. First, the substrate was
`heated to 1050 °C in a stream of hydrogen. Then, the sub­
`strate temperature was lowered to 510 °C to grow the GaN
`buffer layer. The thickness of the GaN buffer layer was about
`300 A. Next, the substrate temperature was elevated to
`1020 °C to grow GaN films. During the deposition, the flow
`rates of N H 3, T M G , and SiH4 (10 ppm SiH4 in H 2) in the
`main flow were maintained at 4.0 /"/min, 30 ^umol/min, and
`4 nmol/min, respectively. The flow rates of H 2 and N 2 in the
`subflow were both maintained at 10 //m in . The Si-doped
`GaN films were grown for 60 min. The thickness of the
`Si-doped GaN film was approximately 4 pm. After GaN
`growth, a Si-doped Alo isGag^sN layer was grown to the
`thickness of 0.15 pm by flowing T M A and TM G . After Si-
`doped AIq i5Gaog5N growth, the temperature was decreased
`to 800 °C, and the Zn-doped IngoeGag 94N layer was grown
`for 15 min. During the Inoo5Gao94N deposition, the flow
`rates of T M I, TEG, and N H 3 in the main flow were main­
`tained at 17 yitm/min, 1.0 yumol/min, and 4.0 //m in , respec­
`tively. The Zn-doped InGaN films were grown by introduc­
`ing D EZ at the flow rate of 10 nmol/min. The thickness of
`the Zn-doped InGaN layer was about 500 A. After the Zn-
`doped InGaN growth, the temperature was
`increased to
`1020 °C to grow Mg-doped p-type Al„ jjGao gjN and GaN
`layers by introducing T M A , T M G , and Cp2Mg gases. The
`thicknesses of the Mg-doped p-type Alg ijGaogsN and GaN
`layers were 0.15 and 0.5 pm, respectively. A p-type GaN
`layer was grown as the contact layer of a p-type electrode in
`order to improve Ohmic contact. After the growth, N j ambi­
`ent thermal annealing was performed to obtain a highly
`p-type GaN layer at a temperature of 700 °C .’^ With this
`thermal annealing technique, the entire area of the as-grown
`p-type GaN layer uniformly becomes a highly p-type GaN
`layer.** Fabrication of LED chips was accomplished as fol­
`lows. The surface of the p-type GaN layer was partially
`etched until the n-type GaN layer was exposed. Next, a
`Ni/Au contact was evaporated onto the p-type GaN layer and
`a Ti/A l contact onto the «-type GaN layer. The wafer was cut
`into a rectangular shape. These chips were set on the lead
`frame, and were then molded. The characteristics of LEDs
`
`Appl. Phys. Lett. 64 (13), 28 March 1994
`
`0003-6951/94/64(13)/1687/3/$6.00
`
`© 1994 American Institute of Physics
`
`TCL 1024, Page 6TCL 1024, Page 6
`1687
`
`

`

`p-Electrode
`
`y
`
`p-GaN
`p-AIGaN
`Zn-doped InUaN
`n-AlGaN
`
`n-GaN
`
`GaN Buffer Layer
`
`Sapphire Substrate
`
`n-Electrode
`
`FIG. 1. The structure of the InGaN/AlGaN double-heterostructure blue
`LED.
`
`were measured under dc-biased conditions at room tempera­
`ture. Figure 1 shows the structure of the InGaN/AlGaN D H
`LEDs.
`Figure 2 shows the electroluminescence (EL) spectra of
`the InGaN/AlGaN D H LEDs at forward currents of 10, 20,
`30, and 40 mA. The peak wavelength is 450 nm and the full
`width at half-maximum (F W H M ) of the peak emission is 70
`nm at each current. The peak wavelength and the F W H M are
`almost constant under these dc-biased conditions. In the PL
`measurements, Zn-related emission energy obtained with Zn
`doping into InGaN was about 0.5 eV lower than the BE
`emission energy of InGaN depending on the indium mole
`fraction. Therefore, the energy level of Zn in InGaN is al­
`most the same as that of Cd in InGaN, and the peak position
`of E L of D H LEDs depends on the indium mole fraction of
`InGaN.'^ Zn doping into InGaN films w ill be described in
`other articles in detail. The output power is shown as a func­
`tion of the forward current in Fig. 3. The output power in­
`creases sublinearly up to 40 m A as a function of the forward
`current. The output powers of the InGaN/AlGaN D H LEDs
`are 800 /iW at 10 mA, 1500 fiW at 20 mA, and 2500 yuW at
`40 mA. The external quantum efficiency is 2.7% at 20 mA. A
`typical on-axis luminous intensity of D H LEDs with 15°
`
`Forward Current (mA)
`
`FIG. 3. The output power of the InGaN/AlGaN double-heterostructure blue
`LED as a function of the forward current.
`
`cone viewing angle is 1.2 cd at 20 mA. This luminous inten­
`sity is the highest value ever reported for blue LEDs. A typi­
`cal example of the current-voltage ( /- V ) characteristics of
`InGaN/AlGaN D H LEDs is shown in Fig. 4. It is shown that
`the forward voltage is 3.6 V at 20 mA. This forward voltage
`is the lowest value ever reported for III-V nitride LEDs. In
`previous reports on InGaN/GaN D H LEDs, the forward volt­
`age was as high as about 10 V and the output power was not
`so high (about 125 /aW ).“ In the previous study, electron
`beam irradiation instead of thermal annealing was performed
`for as-grown InGaN/GaN epilayers in order to obtain a
`highly p-type GaN layer. It is considered that the forward
`voltage was as high as 10 V and the output power was not so
`high because the entire area of the p layer was not uniformly
`changed into a highly p-type GaN layer by electron beam
`irradiation. By thermal annealing, the entire area of as-grown
`high-resistivity p-type GaN layer can be uniformly changed
`into a low-resistivity p-type GaN layer.'*
`InGaN/
`In summary, candela-class high-brightness
`AlGaN D H blue LEDs with the luminous intensity over 1 cd
`were fabricated for the first time. The output power was 1500
`p W and the external quantum efficiency was as high as 2.7%
`at a forward current of 20 m A at room temperature. The peak
`wavelength and the F W H M of the EL were 450 and 70 nm,
`respectively. This value of luminous intensity was the high-
`
`llll
`
`5mA/div.
`
`0 I— —
`300
`
`^
`
`----------------------
`600
`700
`800
`500
`400
`Wavelength (nm)
`
`X; 2V/div.
`
`FIG. 2. Electroluminescence spectra of the InGaN/AlGaN double-
`heterostructure blue LED under different dc currents.
`
`FIG, 4. Typical I-V characteristic of
`heterostructure blue LED.
`
`the
`
`InGaN/AlGaN double-
`
`1688
`
`Appl. Phys. Lett., Vol. 64, No. 13, 28 March 1994
`
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