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30 Sep 2002

Volume 81, Issue 14, pp. 2493-2662

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Colloidal photonic crystal microchannel array with periodically modulated thickness

H. Míguez, S. M. Yang, and G. A. Ozin

Appl. Phys. Lett. 81, 2493 (2002); http://dx.doi.org/10.1063/1.1510959 (3 pages) | Cited 9 times

Online Publication Date: 23 September 2002

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Here we report on the optical properties of a micrometer scale array of periodically modulated thickness colloidal crystals. A combination of soft-lithography, micromolding, and microfluidics techniques is employed to form rectangular microchannels that can impose a periodic modulation of the thickness of colloidal crystals grown within them. Correspondingly, a periodic fluctuation of the photonic band structure occurs at distances of the order of a few microns. Experimental evidence of this effect is obtained by optical microspectroscopy. Results are analyzed in terms of finite crystal size theoretical calculations. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.82.Cr Fabrication techniques; lithography, pattern transfer
82.70.Dd Colloids
81.10.Fq Growth from melts; zone melting and refining
47.85.Np Fluidics
42.86.+b Optical workshop techniques

All-optical cw laser polarization conversion at 1.55 μm by two-beam coupling in nematic liquid crystal films

I. C. Khoo and J. Ding

Appl. Phys. Lett. 81, 2496 (2002); http://dx.doi.org/10.1063/1.1510965 (3 pages) | Cited 13 times

Online Publication Date: 23 September 2002

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We have demonstrated efficient all-optical polarization conversion of cw 1.55 μm laser in nematic liquid crystal films. The process is mediated by coherent two-beam coupling effect between an incident polarized laser and its orthogonally polarized noise component scattered by the director axis fluctuations. We report here a quantitative theory that accounts for severe pump depletion and high-efficiency polarization conversion and demonstrate good agreement with experimental observations. © 2002 American Institute of Physics.
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42.70.Df Liquid crystals
42.25.Ja Polarization
42.25.Lc Birefringence
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation

Two-dimensional photonic crystal hexagonal waveguide ring laser

Se-Heon Kim, Han-Youl Ryu, Hong-Gyu Park, Guk-Hyun Kim, Yong-Seok Choi, Yong-Hee Lee, and Jeong-Soo Kim

Appl. Phys. Lett. 81, 2499 (2002); http://dx.doi.org/10.1063/1.1510583 (3 pages) | Cited 38 times

Online Publication Date: 23 September 2002

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Hexagonal ring-type resonators defined by two-dimensional photonic crystal waveguides are proposed and demonstrated. Lasing actions are observed from the photonic crystal ring resonator patterned on a free-standing slab with InGaAsP active layers emitting near 1.55 μm. For a ring resonator with 8-μm diameter, the threshold peak pump power is ∼3 mW. The quality factor of the ring resonator mode estimated from below-threshold linewidth shows that the sum of the propagation loss and the bending loss of the photonic crystal ring resonator is less than ∼ 260 cm−1. The photonic crystal ring resonators can be used for the characterization of the optical losses in photonic crystal waveguides. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.70.Qs Photonic bandgap materials
42.60.By Design of specific laser systems

Wavelength tunable ultrashort pulse generation from a passively mode-locked asymmetric-quantum-well semiconductor laser

M. J. Brennan, J. N. Milgram, P. Mascher, and H. K. Haugen

Appl. Phys. Lett. 81, 2502 (2002); http://dx.doi.org/10.1063/1.1510587 (3 pages) | Cited 2 times

Online Publication Date: 23 September 2002

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Optical pulses are generated from a passively mode-locked dual asymmetric-quantum-well semiconductor laser mounted in a linear external cavity. The devices are fabricated with two sections, one of which contains a bend in the waveguide for external cavity coupling. Pulses 2.0–3.9 ps in duration have been generated, which are tunable over 61 nm, from 954 to 1015 nm. Pulse compression yields durations as short as 470 fs with peak powers as high as 1.5 W. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

InGaAsP/InP avalanche photodiodes for photon counting at 1.06 μm

K. A. McIntosh, J. P. Donnelly, D. C. Oakley, A. Napoleone, S. D. Calawa, L. J. Mahoney, K. M. Molvar, E. K. Duerr, S. H. Groves, and D. C. Shaver

Appl. Phys. Lett. 81, 2505 (2002); http://dx.doi.org/10.1063/1.1509469 (3 pages) | Cited 26 times

Online Publication Date: 23 September 2002

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Geiger-mode (photon-counting) operation at 1.06 μm has been demonstrated with InGaAsP/InP avalanche photodiodes operated at room temperature. A photon detection efficiency of 33% was measured on uncoated detectors, representing an internal avalanche probability of 60%. Under identical bias conditions a dark count rate as low as 1.7 MHz was measured at 290 K, consistent with a primary dark current of <0.3 pA. Dark count rates drop by approximately 50–200× by cooling the detectors to 210 K (−63 °C). © 2002 American Institute of Physics.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.60.Gz Photodetectors (including infrared and CCD detectors)
73.61.Ey III-V semiconductors
72.40.+w Photoconduction and photovoltaic effects

1 mW AlInGaN-based ultraviolet light-emitting diode with an emission wavelength of 348 nm grown on sapphire substrate

T. Wang, Y. H. Liu, Y. B. Lee, J. P. Ao, J. Bai, and S. Sakai

Appl. Phys. Lett. 81, 2508 (2002); http://dx.doi.org/10.1063/1.1510967 (3 pages) | Cited 42 times

Online Publication Date: 23 September 2002

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By introducing the AlInGaN/AlGaN quaternary system as an active region, we fabricated an UV light-emitting diode (LED) with an emission wavelength of 348 nm. The optical power is 1 mW at an injection current of 50 mA under a bare-chip geometry, which is the highest report among UV–LEDs with an emission wavelength of around 350 nm grown on sapphire substrate. It means that the optical power of such LEDs is high enough to be used in practical application. In contrast to it, a similar UV–LED based on GaN/AlGaN system as an active region has been also grown, whose optical power is less than that of the AlInGaN/AlGaN-based UV–LED by one order of magnitude. The temperature-dependent photoluminescence study indicates that there exists a strong exciton-localization effect in the AlInGaN/AlGaN material system, while there is no distinguished exciton-localization effect in the GaN/AlGaN material system. Therefore, the high performance of the AlInGaN/AlGaN-based UV–LED can be attributed to the enhanced exciton-localization effect. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors

Random lasing following two-photon excitation of highly scattering gain media

Giannis Zacharakis, Nektarios A. Papadogiannis, and Theodore G. Papazoglou

Appl. Phys. Lett. 81, 2511 (2002); http://dx.doi.org/10.1063/1.1511284 (3 pages) | Cited 16 times

Online Publication Date: 23 September 2002

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We present experimental evidence of laser emission following two-photon excitation of dye-infiltrated random gain media with optical properties similar to biological tissue. The excitation was performed with femtosecond laser pulses at 800 nm and the emission (at 480 nm) was recorded with a spectrograph streak camera system. The coherent properties of the random lasing emission were also investigated by performing single photon counting. The applications of coherent laser light that can be emitted deep inside a random medium are far reaching, particularly for imaging and therapeutic purposes. © 2002 American Institute of Physics.
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42.55.Mv Dye lasers
42.55.Rz Doped-insulator lasers and other solid state lasers
42.62.Be Biological and medical applications
87.63.L- Visual imaging
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.50.Ar Photon statistics and coherence theory
42.25.Fx Diffraction and scattering
42.25.Dd Wave propagation in random media

Demonstration and optical characteristics of electro-optic Bragg modulators in periodically poled lithium niobate in the near-infrared

J. A. Abernethy, C. B. E. Gawith, R. W. Eason, and P. G. R. Smith

Appl. Phys. Lett. 81, 2514 (2002); http://dx.doi.org/10.1063/1.1510964 (3 pages) | Cited 23 times

Online Publication Date: 23 September 2002

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We report the infrared operation of a bulk optical Bragg modulator based on electro-optically induced refractive index gratings in z-cut periodically poled lithium niobate. Efficiencies in the first order of 45% for 1064 nm e-polarized light and 30% for o-polarized light were achieved, with maximum on/off ratios of 15:1 and 9:1, respectively. Field-induced light scattering effects due to poling are observed at higher drive voltages and compromised device performance due to these scattering effects is predicted to limit long-wavelength operation of these devices. © 2002 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators
42.79.Dj Gratings

Improved transmission characteristics of moderate refractive index contrast photonic crystal slabs

G. Böttger, C. Liguda, M. Schmidt, and M. Eich

Appl. Phys. Lett. 81, 2517 (2002); http://dx.doi.org/10.1063/1.1511816 (3 pages) | Cited 16 times

Online Publication Date: 23 September 2002

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Finite two-dimensional (2D)-photonic crystal slab waveguide structures from moderate refractive index materials have been investigated theoretically and results were compared with experimental data. 3D-finite difference time domain (3D-FDTD) simulations reveal a strong dependence of the transmission on the etching depth. For structures with etching depths less than the waveguide core thickness, both a substantial leakage of optical power to the substrate and a spatial mismatch of the transmitted field to the waveguide mode were found, leading to unsatisfactory transmissions. These losses occur mainly on the airband side of the spectrum where the optical field is concentrated in the holes. However, hole depths extending into the substrate by only 0.5 μm lead to an almost perfect mode match at transmission values exceeding 90%. © 2002 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.70.Qs Photonic bandgap materials
02.70.Bf Finite-difference methods

Submicron extreme ultraviolet imaging using high-harmonic radiation

Marek Wieland, Rolf Frueke, Thomas Wilhein, Christian Spielmann, Martin Pohl, and Ulf Kleineberg

Appl. Phys. Lett. 81, 2520 (2002); http://dx.doi.org/10.1063/1.1511288 (3 pages) | Cited 18 times

Online Publication Date: 23 September 2002

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We report on experiments using high-harmonic (HH) radiation for microscopy imaging at 13 nm wavelength. A simple setup using a zone plate as objective and a back-illuminated CCD as detector yields at moderate magnifications of M ≈ 60 a spatial resolution of δx<0.8 μm demonstrated with a sample of mica. The HH radiation was monochromatized by means of a high-efficiency multilayer monochromator consisting of two Mo/Si-mirros. © 2002 American Institute of Physics.
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07.60.Pb Conventional optical microscopes
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Bh Lenses, prisms and mirrors
41.85.Si Particle beam collimators, monochromators
42.79.Nv Optical frequency converters

Low-threshold-current-density 1300-nm dilute-nitride quantum well lasers

Nelson Tansu, Nicholas J. Kirsch, and Luke J. Mawst

Appl. Phys. Lett. 81, 2523 (2002); http://dx.doi.org/10.1063/1.1511290 (3 pages) | Cited 80 times

Online Publication Date: 23 September 2002

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Metalorganic chemical vapor deposition-grown In0.4Ga0.6As0.995N0.005 quantum well (QW) lasers have been realized, at an emission wavelength of 1.295 μm, with threshold and transparency current densities as low as 211 A/cm2 (for L=2000 μm) and 75 A/cm2, respectively. The utilization of a tensile-strained GaAs0.67P0.33 buffer layer and GaAs0.85P0.15 barrier layers allows a highly-compressively-strained In0.4Ga0.6As0.995N0.005 QW to be grown on a high-Al-content lower cladding layer, resulting in devices with high current injection efficiency (ηinj ∼ 97%). © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
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Self-sustained photoelectron discharge

P. A. Bokhan and D. E. Zakrevsky

Appl. Phys. Lett. 81, 2526 (2002); http://dx.doi.org/10.1063/1.1511289 (3 pages) | Cited 4 times

Online Publication Date: 23 September 2002

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This letter reports a discharge structure with a self-sustained photoelectron discharge. Specific to this discharge is its ability to generate electron beams with an energy of several keV and virtually 100% efficiency. A mechanism underlying the high efficiency of electron beam generation observed is proposed; the conditions required for pulse and continuous photoelectron discharge are determined. © 2002 American Institute of Physics.
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52.80.-s Electric discharges
41.75.Fr Electron and positron beams

Power dissipation mode transition by a magnetic field

S. J. You, C. W. Chung, K. H. Bai, and H. Y. Chang

Appl. Phys. Lett. 81, 2529 (2002); http://dx.doi.org/10.1063/1.1506944 (3 pages) | Cited 13 times

Online Publication Date: 23 September 2002

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We measured electrical characteristics of transversely magnetized capacitively coupled plasma at low pressure (10 mTorr). From these measurements, we found that the power characteristics of the magnetized discharge were different from those of the unmagnetized discharge. As the magnetic field increases, a square dependence of power characteristic at high current changes to a linear dependence. This can be understood as a power dissipation mode transition by a magnetic field. A calculation from a simple sheath model agrees well with the experimental data. © 2002 American Institute of Physics.
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52.80.-s Electric discharges
52.40.Kh Plasma sheaths
52.65.-y Plasma simulation
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Enhanced second-order nonlinear optical response of LiNbO3 films upon Er doping

J. Gonzalo, J. A. Chaos, A. Suárez-García, C. N. Afonso, and V. Pruneri

Appl. Phys. Lett. 81, 2532 (2002); http://dx.doi.org/10.1063/1.1506949 (3 pages) | Cited 2 times

Online Publication Date: 23 September 2002

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Erbium-doped LiNbO3 films have been produced in a single-step process by alternate pulsed laser deposition. The dopant is incorporated in submonolayers whose nominal indepth separation is varied in the range 1.7–4.0 nm to lead respectively to Er concentrations in the range 3.4–0.6×1020 atoms/cm−3. All the films exhibit the characteristic Er3+ photoluminescence at 1.54 μm with lifetime values as high as 3 ms. The d33 nonlinear coefficients determined from second-harmonic generation experiments are in the range 22–28 pm/V, the films having nominal Er submonolayer indepth separation of 3–4 nm exhibiting d33 values slightly above that of the bulk material. The comparison of the d33 values obtained in the Er-doped films to those reported earlier for similar undoped films shows clearly that both the structural quality and the second-harmonic performance of the films can be enhanced by Er doping. © 2002 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Mp Nonlinear optical crystals
78.66.Nk Insulators
68.55.-a Thin film structure and morphology
81.15.Fg Pulsed laser ablation deposition

Dynamical x-ray microscopy investigation of electromigration in passivated inlaid Cu interconnect structures

G. Schneider, G. Denbeaux, E. H. Anderson, B. Bates, A. Pearson, M. A. Meyer, E. Zschech, D. Hambach, and E. A. Stach

Appl. Phys. Lett. 81, 2535 (2002); http://dx.doi.org/10.1063/1.1509465 (3 pages) | Cited 22 times

Online Publication Date: 23 September 2002

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Quantitative time-resolved x-ray microscopy mass transport studies of the early stages of electromigration in an inlaid Cu line/via structure were performed with about 40 nm lateral resolution. The image sequences show that void formation is a highly dynamic process, with voids being observed to nucleate and grow within the Cu via and migrate towards the via sidewall. Correlation of the real time x-ray microscopy images with postmortem high voltage electron micrographs of the sample indicates that the void nucleation occurs at the site of grain boundaries in Cu, and that the voids migrate along these grain boundaries during electromigration. © 2002 American Institute of Physics.
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85.40.Ls Metallization, contacts, interconnects; device isolation
85.40.Qx Microcircuit quality, noise, performance, and failure analysis
07.85.Tt X-ray microscopes
66.30.Qa Electromigration
81.65.Rv Passivation
61.72.Qq Microscopic defects (voids, inclusions, etc.)
61.72.Mm Grain and twin boundaries

Superhigh-frequency surface-acoustic-wave transducers using AlN layers grown on SiC substrates

Y. Takagaki, P. V. Santos, E. Wiebicke, O. Brandt, H.-P. Schönherr, and K. H. Ploog

Appl. Phys. Lett. 81, 2538 (2002); http://dx.doi.org/10.1063/1.1509471 (3 pages) | Cited 25 times

Online Publication Date: 23 September 2002

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We demonstrate the operation of surface-acoustic-wave (SAW) transducers fabricated on AlN/SiC structures at frequencies as high as 19 GHz. The high SAW velocity of the AlN film is enhanced by the even higher sound velocity of the SiC substrate, enabling us to achieve these frequencies with a SAW wavelength of 400 nm. © 2002 American Institute of Physics.
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43.38.Rh Surface acoustic wave transducers
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
68.35.Iv Acoustical properties

Method to measure shear moduli of nonequilibrium phases pseudomorphically stabilized in superlattices

V. Pankov, M. Evstigneev, and R. H. Prince

Appl. Phys. Lett. 81, 2541 (2002); http://dx.doi.org/10.1063/1.1510966 (3 pages)

Online Publication Date: 23 September 2002

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A method to measure shear moduli of nonequilibrium phases pseudomorphically stabilized in superlattices is proposed. The method is based on the use of a stress-free coherent superlattice as a modeling structure whereby the lattice misfit strain is distributed between the individual layers according to their shear moduli and Poisson ratios. The method is applied to estimate the shear modulus of the nonequilibrium rocksalt-type (B1) AlN phase pseudomorphically stabilized in AlN/TiN superlattices. The value of shear modulus of B1–AlN in these superlattices was found to increase from 288±50 GPa to 457±80 GPa with decreasing bilayer thickness from 1 to 0.6 nm. © 2002 American Institute of Physics.
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81.70.Bt Mechanical testing, impact tests, static and dynamic loads
68.65.Cd Superlattices
68.35.Gy Mechanical properties; surface strains

Micro-Raman studies of vertical-cavity surface-emitting lasers with AlxOy/GaAs distributed Bragg reflectors

V. A. Haisler, F. Hopfer, R. L. Sellin, A. Lochmann, K. Fleischer, N. Esser, W. Richter, N. N. Ledentsov, D. Bimberg, C. Möller, and N. Grote

Appl. Phys. Lett. 81, 2544 (2002); http://dx.doi.org/10.1063/1.1511533 (3 pages) | Cited 10 times

Online Publication Date: 23 September 2002

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Micro-Raman spectroscopy studies of the oxidation processes in high Al content AlxGa1−xAs layers used in distributed Bragg reflectors (DBRs) in vertical-cavity surface-emitting lasers (VCSELs) are presented. Precise characterization of the composition of oxidized layers, control over residual As precipitates, as well as the determination of the mechanical strain in DBR layers is demonstrated. Proper optimization of the processing steps on the basis of Micro-Raman spectroscopy allows the realization of reliable oxide-DBR VCSELs. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
81.65.Mq Oxidation

Photoluminescence upconversion in 4H–SiC

Mt. Wagner, I. G. Ivanov, L. Storasta, J. P. Bergman, B. Magnusson, W. M. Chen, and E. Janzén

Appl. Phys. Lett. 81, 2547 (2002); http://dx.doi.org/10.1063/1.1511813 (3 pages) | Cited 1 time

Online Publication Date: 23 September 2002

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Efficient photoluminescence upconversion is observed in 4H–SiC samples containing both the UD-3 defect and the titanium impurity. In this process, the titanium photoluminescence emission with no-phonon (NP) lines at 2.848 eV (A0) and 2.789 eV (B0) can be excited by tuning the laser to the NP line of UD-3 at 1.356 eV. In samples containing either only UD-3 or only titanium, a different photoluminescence upconversion process can be observed, which occurs at photon energies higher than ∼ 1.5 eV without exhibiting sharp features. At least one of the two processes generates both free electrons and free holes and can, therefore, be a candidate for an important recombination channel. © 2002 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
81.05.Hd Other semiconductors
71.55.Ht Other nonmetals

Multiple splitting of G-band modes from individual multiwalled carbon nanotubes

Xinluo Zhao, Yoshinori Ando, Lu-Chang Qin, Hiromichi Kataura, Yutaka Maniwa, and Riichiro Saito

Appl. Phys. Lett. 81, 2550 (2002); http://dx.doi.org/10.1063/1.1502196 (3 pages) | Cited 26 times

Online Publication Date: 23 September 2002

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Surface-enhanced Raman scattering spectra of an individual multiwalled carbon nanotube (MWNT) with the innermost diameter ∼ 1 nm, prepared by hydrogen arc discharge, show a single peak of radial breathing mode and multiple splitting of the tangential stretching G-band modes. Based on Lorentzian line shape analysis and related theoretical calculations, the G-band modes of MWNT are confirmed to be composed of both G-band modes (linewidth 4 cm−1) from the innermost tube and graphite-like mode (linewidth ∼ 20 cm−1) from the outer cylinders in MWNT. This observation indicates that MWNTs are unique and possess characteristic Raman spectra different from other sp2 carbon allotropes. © 2002 American Institute of Physics.
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78.30.Na Fullerenes and related materials
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Permanent grayscales in bistable twisted nematic liquid-crystal displays

Z. L. Xie, Z. G. Meng, M. Wong, and H. S. Kwok

Appl. Phys. Lett. 81, 2553 (2002); http://dx.doi.org/10.1063/1.1511807 (3 pages) | Cited 2 times

Online Publication Date: 23 September 2002

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Permanent grayscales in a π bistable twisted nematic-liquid-crystal display have been demonstrated. This display can be switched between the −22.5° and 157.5° twist states by a combination of a strong in-plane electric field and a vertical electric field for creating both planar anchoring breaking and an electrohydrodynamic backflow. The switching of the twist states during the Frederiks transition is sufficiently inhomogeneous such that domains of −22.5° and 157.5° twisted states can coexist permanently. The ratio of these domains can be controlled by the vertical electric field. © 2002 American Institute of Physics.
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42.79.Kr Display devices, liquid-crystal devices

Three-dimensional band mapping of graphite

Fumihiko Matsui, Yoshiaki Hori, Hiroaki Miyata, Nobutaka Suganuma, Hiroshi Daimon, Hidekazu Totsuka, Koji Ogawa, Tomoya Furukubo, and Hidetoshi Namba

Appl. Phys. Lett. 81, 2556 (2002); http://dx.doi.org/10.1063/1.1511818 (3 pages) | Cited 22 times

Online Publication Date: 23 September 2002

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We developed a method to visualize the curved surfaces of valence band dispersion by a display-type spherical mirror analyzer. The π and σ band “surfaces” of graphite measured and displayed three dimensionally contain fruitful information compared to the conventional band dispersion “curves” along a certain direction in k space. The slope and the curvature of local band structure correspond to the velocity and the mass of the valence electrons. By integrating band energy over the entire Brillouin zone, the electronic part of the condensation energy is obtained. Furthermore, the atomic orbitals composing each band are determined from two-dimensional photoelectron intensity distribution by using linearly polarized synchrotron radiation. © 2002 American Institute of Physics.
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71.20.Ps Other inorganic compounds
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Sensitive detection of voids in solid materials by refraction-enhanced synchrotron radiation imaging

Keiko Imamura, Norishige Ehara, Keiji Umetani, Keiko Miyamoto, Yoshihide Kanemaki, Kentarou Uesugi, Yoichi Inada, Haruki Ogata, Yasuo Nakajima, and Mamoru Fukuda

Appl. Phys. Lett. 81, 2559 (2002); http://dx.doi.org/10.1063/1.1510585 (2 pages) | Cited 1 time

Online Publication Date: 23 September 2002

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Voids in opaque materials (minute air bubbles) were imaged with synchrotron radiation in a refraction enhancement mode. The voids are imaged by an enhanced x-ray intensity inside the bubble, surrounded by a border region with decreased x-ray intensity, thus allowing sensitive detection of air bubbles in plastic materials. As those “impurities” could not be depicted with conventional radiography, and optical inspection is not useful if the matrix is opaque, this in-situ imaging technique offers the potential to obtain information of air inclusions, voids, and cracking that appear inadvertently in opaque plastics and possibly in metals as well. © 2002 American Institute of Physics.
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81.70.Ex Nondestructive testing: electromagnetic testing, eddy-current testing
07.85.Qe Synchrotron radiation instrumentation
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Evaluation of the thermal stability of a Cu60Hf25Ti15 metallic glass

Dmitri V. Louzguine and Akihisa Inoue

Appl. Phys. Lett. 81, 2561 (2002); http://dx.doi.org/10.1063/1.1509466 (2 pages) | Cited 24 times

Online Publication Date: 23 September 2002

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The present letter shows how a continuous heating transformation diagram for a Cu60Hf25Ti15 metallic glass can be obtained by applying an extension of the Kissinger analysis. According to the calculation this glass is completely stable in the Earth’s climate for its lifetime. This extension of the Kissinger analysis method can be applied to any other metallic glass. © 2002 American Institute of Physics.
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65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
64.70.K- Solid-solid transitions
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Application of low-temperature area-selective regrowth for ultrashallow sidewall GaAs tunnel junctions

Yutaka Oyama, Takeo Ohno, Kenji Tezuka, Ken Suto, and Jun-ichi Nishizawa

Appl. Phys. Lett. 81, 2563 (2002); http://dx.doi.org/10.1063/1.1510162 (3 pages) | Cited 9 times

Online Publication Date: 23 September 2002

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Low-temperature (290 °C) area-selective regrowth by the intermittent injection of precursors in an ultrahigh vacuum was applied for the fabrication of ultrashallow sidewall GaAs tunnel junctions with the junction area in the order of 10−8 cm2. The tunnel junctions on the normal mesa orientation have shown the record peak current density up to 31 000 A/cm2 and negative differential conductance of −1.4×10−5 S at 100 μm long strip structure. The peak current density of tunnel junctions has shown strong sidewall orientation dependences with the order of {111}A>{110}>{111}B. © 2002 American Institute of Physics.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
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