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28 Jul 2008

Volume 93, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 93, 043101 (2008); http://dx.doi.org/10.1063/1.2963352 (3 pages)

Xin Fu, Jun Jiang, Wenzheng Zhang, and Jun Yuan
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Infrared emission from the substrate of GaAs-based semiconductor lasers

Mathias Ziegler, Robert Pomraenke, Max Felger, Jens W. Tomm, Parinda Vasa, Christoph Lienau, Marwan Bou Sanayeh, Alvaro Gomez-Iglesias, Martin Reufer, Frank Bugge, and Götz Erbert

Appl. Phys. Lett. 93, 041101 (2008); http://dx.doi.org/10.1063/1.2959854 (3 pages) | Cited 2 times

Online Publication Date: 28 July 2008

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We report on the origin of three additional low-energy spontaneously emitted bands in GaAs-based broad-area laser diodes. Spectrally and spatially resolved scanning optical microscopy and Fourier-transform infrared spectroscopy assign the different contributions to bandtail-related luminescence from the gain region as well as interband and deep-level-related luminescences from the GaAs substrate. The latter processes are photoexcited due to spontaneous emission from the active region followed by a cascaded photon-recycling process within the substrate.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Polarization-matched GaInN/AlGaInN multi-quantum-well light-emitting diodes with reduced efficiency droop

Martin F. Schubert, Jiuru Xu, Jong Kyu Kim, E. Fred Schubert, Min Ho Kim, Sukho Yoon, Soo Min Lee, Cheolsoo Sone, Tan Sakong, and Yongjo Park

Appl. Phys. Lett. 93, 041102 (2008); http://dx.doi.org/10.1063/1.2963029 (3 pages) | Cited 95 times

Online Publication Date: 28 July 2008

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Blue multi-quantum-well light-emitting diodes (LEDs) with GaInN quantum wells and polarization-matched AlGaInN barriers are grown by metal-organic chemical vapor deposition. The use of quaternary alloys enables an independent control over interface polarization charges and bandgap and has been suggested as a method to reduce electron leakage from the active region, a carrier loss mechanism that can reduce efficiency at high injection currents—an effect known as the efficiency droop. The GaInN/AlGaInN LEDs show reduced forward voltage, reduced efficiency droop, and improved light-output power at large currents compared to conventional GaInN/GaN LEDs.
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85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.60.Jb Light-emitting devices
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Enhanced photoluminescence from germanium-based ring resonators

Peng Huei Lim, Yosuke Kobayashi, Shinya Takita, Yasuhiko Ishikawa, and Kazumi Wada

Appl. Phys. Lett. 93, 041103 (2008); http://dx.doi.org/10.1063/1.2950087 (3 pages) | Cited 11 times

Online Publication Date: 29 July 2008

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We report the enhancement of direct bandgap emission from germanium ring resonators based on silicon-on-insulator (SOI). As a consequence of their strong confinement, a record quality factor (Q) of 620 is obtained that is an order of magnitude higher than that previously characterized for crystalline germanium microcavities. We also describe a pump power dependency of Q due to bandedge shifts not previously reported for silicon-or germanium-based emitters. A decline in the relative peak to baseline intensities with lower Qs is attributed to the Purcell effect on account of the wavelength-scale dimensions and high index contrast of our samples.
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42.79.-e Optical elements, devices, and systems
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.55.Ap Elemental semiconductors

Simultaneous forward and backward terahertz generations in periodically poled stoichiometric LiTaO3 crystal using femtosecond pulses

N. E. Yu, C. Kang, H. K. Yoo, C. Jung, Y. L. Lee, C.-S. Kee, D.-K. Ko, J. Lee, K. Kitamura, and S. Takekawa

Appl. Phys. Lett. 93, 041104 (2008); http://dx.doi.org/10.1063/1.2960999 (3 pages) | Cited 4 times

Online Publication Date: 29 July 2008

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Forward and counterpropagated backward terahertz generations were demonstrated via difference frequency generation using a femtosecond laser. By cooling the crystal to reduce terahertz losses, we achieved the terahertz generations of 1.36 and 0.65 THz. Temperature-dependent measurements showed gradual intensity increase of the terahertz pulse and red shift of the center frequency as the temperature decrease from 255 to 143 K, although there were insignificant decreases of the spectral bandwidth.
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42.70.Mp Nonlinear optical crystals
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Enhanced light extraction efficiency from AlGaInP thin-film light-emitting diodes with photonic crystals

K. Bergenek, Ch. Wiesmann, R. Wirth, L. O’Faolain, N. Linder, K. Streubel, and T. F. Krauss

Appl. Phys. Lett. 93, 041105 (2008); http://dx.doi.org/10.1063/1.2963030 (3 pages) | Cited 7 times

Online Publication Date: 29 July 2008

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We investigate the use of photonic crystals for light extraction from high-brightness thin-film AlGaInP light-emitting diodes with different etch depths, lattice constants, and two types of lattices (hexagonal and Archimedean). Both simulations and experimental results show that the extraction of high order modes with a low effective index neff is most efficient. The highest external quantum efficiency without encapsulation is 19% with an Archimedean A7 lattice with reciprocal lattice constant G = 1.5 k0, which is 47% better than an unstructured reference device.
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85.60.Jb Light-emitting devices
42.70.Qs Photonic bandgap materials

Strong terahertz conductance of graphene nanoribbons under a magnetic field

Junfeng Liu, A. R. Wright, Chao Zhang, and Zhongshui Ma

Appl. Phys. Lett. 93, 041106 (2008); http://dx.doi.org/10.1063/1.2964093 (3 pages) | Cited 24 times

Online Publication Date: 29 July 2008

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We demonstrate that the optical response of graphene nanoribbons in the terahertz to far-infrared regime can be significantly enhanced and tuned by an applied magnetic field. The dependence of the threshold frequency on the magnetic field is studied. The ribbons with the strongest terahertz conductance under a magnetic field are those with one-dimensional massless Dirac Fermion energy dispersion. For a given ribbon, there exists an optimal field under which the conductance resonance can occur at the lowest frequency.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.-j Infrared and Raman spectra
71.20.Tx Fullerenes and related materials; intercalation compounds

Slab waveguides and nanoscale patterning of pulsed laser-deposited Ge0.2Se0.8 chalcogenide films

W. C. Liu, G. Hoffman, W. Zhou, R. M. Reano, P. Boolchand, and R. Sooryakumar

Appl. Phys. Lett. 93, 041107 (2008); http://dx.doi.org/10.1063/1.2965124 (3 pages) | Cited 2 times

Online Publication Date: 29 July 2008

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Planar slab waveguides were fabricated by pulsed laser deposition from GexSe1−x glass compounds with composition (x ∼ 0.2) that lies very close to the floppy to rigid stiffness transition. These high quality active structures, which were deposited on SiO2 cladding layers above silicon substrates, support several transverse-electric (TE) modes, and a loss of 0.24 dB/cm for the TE0 mode was measured at 632.8 nm wavelength. The ability to exploit electron beam writing at these special Ge in Se compositions to create nanoscale surface motifs are promising advances to create unique miniature optical processing devices.
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81.16.Rf Micro- and nanoscale pattern formation
81.15.Fg Pulsed laser ablation deposition

A pure 1.5 μm electroluminescence from metal-oxide-silicon tunneling diode using dislocation network

X. Yu, W. Seifert, O. F. Vyvenko, M. Kittler, T. Wilhelm, and M. Reiche

Appl. Phys. Lett. 93, 041108 (2008); http://dx.doi.org/10.1063/1.2965126 (3 pages) | Cited 8 times

Online Publication Date: 29 July 2008

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This letter has demonstrated a light emitting diode (LED) with a pure 1.5 μm emission using a metal-oxide-silicon (MOS) tunneling structure based on dislocation network in direct silicon bond wafer. It is found that under negative gate bias, the electrons in the metal gate electrode tunnel through the thin oxide to silicon and then recombine radiatively with holes at the dislocation related states to emit the D1-line with a wavelength of 1.5 μm. The calculation of energy band diagram indicates that a potential well for electrons forms at the charged bonding interface under negative bias, therefore, the electrons tunneled from the gate can rapidly be attracted by the electric field and then confined at the interface, which essentially increases the efficiency of D1 luminescence from MOS tunneling LED. These results are of interest for the development of silicon based photonics with 1.5 μm light emission.
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85.60.Jb Light-emitting devices
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
85.30.Tv Field effect devices

Impact of resistance on cathodoluminescence and its application for layer sheet-resistance measurements

A. Czerwinski, M. Pluska, J. Ratajczak, A. Szerling, and J. Kątcki

Appl. Phys. Lett. 93, 041109 (2008); http://dx.doi.org/10.1063/1.2966339 (3 pages) | Cited 4 times

Online Publication Date: 29 July 2008

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The dependence of cathodoluminescence (CL) on resistances in semiconductor structures, especially on layer resistances, is described. The effect can be taken advantage of and used for characterization of sheet resistance of thin layers in semiconductor devices, as illustrated in this paper by an assessment of lateral confinements in semiconductor-laser heterostructures. At the same time, the effect, if neglected, can be detrimental for accuracy of spatially or spectrally resolved CL studies.
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78.60.Hk Cathodoluminescence, ionoluminescence
85.30.De Semiconductor-device characterization, design, and modeling
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

A dual beam photonic crystal fiber trap for microscopic particles

David M. Gherardi, Antonia E. Carruthers, Tomáš Čižmár, Ewan M. Wright, and Kishan Dholakia

Appl. Phys. Lett. 93, 041110 (2008); http://dx.doi.org/10.1063/1.2955518 (3 pages) | Cited 20 times

Online Publication Date: 30 July 2008

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The dual beam counterpropagating optical trap has found increased use in studies such as optical stretching, optical binding, Raman spectroscopy, and the trapping of high index particles. In this letter we demonstrate the use of photonic crystal fiber to realize a long range dual beam trap that may support multiple wavelengths simultaneously. We develop a dual wavelength conveyor belt for trapped particles and realize the first ever dual beam white light (supercontinuum) trap. This low coherence light trap permits long range longitudinal optical binding of microparticles in the trap with no deleterious interference effects.
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42.70.Qs Photonic bandgap materials
42.81.-i Fiber optics
42.50.Wk Mechanical effects of light on material media, microstructures and particles

10 mJ class femtosecond optical parametric amplifier for generating soft x-ray harmonics

Eiji J. Takahashi, Tsuneto Kanai, Yasuo Nabekawa, and Katsumi Midorikawa

Appl. Phys. Lett. 93, 041111 (2008); http://dx.doi.org/10.1063/1.2960352 (3 pages) | Cited 28 times

Online Publication Date: 30 July 2008

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Power scaling of an infrared (IR) parametric amplifier chain, pumped at 800 nm by a terawatt Ti:sapphire laser system has been reported. A total output energy exceeding 10 mJ with 40 fs pulse duration has been achieved in the IR region, which is the highest energy and peak power ever reported for an ultrafast optical parametric amplifier scheme. By applying the developed IR pulses to high-order harmonic generation, we have observed a significant cutoff extension compared to the case of 800 nm driving wavelength. This source suits as a driver laser for extending high-order harmonic photon energy into the kiloelectronvolts region.
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42.65.Yj Optical parametric oscillators and amplifiers
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Laser annealing induced high Ge concentration epitaxial SiGe layer in Si1−xGex virtual substrate

C. Y. Ong, K. L. Pey, X. Li, X. C. Wang, C. M. Ng, and L. Chan

Appl. Phys. Lett. 93, 041112 (2008); http://dx.doi.org/10.1063/1.2962991 (3 pages)

Online Publication Date: 30 July 2008

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Graded silicon germanium (Si1−yGey) epilayer with a thin layer of high Ge concentration ( ∼ 36%) near the surface is obtained by laser thermal annealing (LTA). The graded Si1−yGey layer is formed during a liquid phase regrowth after LTA. The relaxation in this graded Si1−yGey epilayer is insignificant; therefore it can be integrated into the source/drain of the p-type metal-oxide-semiconductor field effect transistor to induce high compressive strain to the Si channel. The thickness of the graded Si1−yGey epilayer and the concentration of the Ge near the surface can be controlled by the laser fluence, which in turn changes the strain induced to the Si channel of strained devices.
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68.55.ag Semiconductors
61.72.Cc Kinetics of defect formation and annealing
85.30.Tv Field effect devices

Spatially resolved cathodoluminescence spectra of excitons in a ZnO microparticle

Takeshi Hirai, Nobuhito Ohno, Yoshiyuki Harada, Taku Horii, Yuji Sawada, and Tadashi Itoh

Appl. Phys. Lett. 93, 041113 (2008); http://dx.doi.org/10.1063/1.2965614 (3 pages) | Cited 5 times

Online Publication Date: 30 July 2008

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Spatially resolved cathodoluminescence (CL) spectra of excitons in a ZnO microparticle, which consists of a number of small particles (primary particles), have been investigated at low temperature (15 K). The spatially resolved CL spectra can be interpreted in terms of the influence of an internal electric field, which is likely caused by transfer of electrons from donor defects to surface states near the surface, on the radiative recombination of free and bound excitons in the ZnO microparticle.
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78.60.Hk Cathodoluminescence, ionoluminescence
71.35.-y Excitons and related phenomena

Probing coherently excited optical phonons by extreme ultraviolet radiation with femtosecond time resolution

E. Papalazarou, D. Boschetto, J. Gautier, T. Garl, C. Valentin, G. Rey, Ph. Zeitoun, A. Rousse, Ph. Balcou, and M. Marsi

Appl. Phys. Lett. 93, 041114 (2008); http://dx.doi.org/10.1063/1.2966180 (3 pages) | Cited 5 times

Online Publication Date: 30 July 2008

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We present a pump-probe experimental approach to study time-resolve coherent optical phonons using light pulses in the extreme ultraviolet wavelength range with femtosecond time resolution. Using this technique, a Bi (111)-oriented single crystal was excited by near-infrared (1.55 eV) pulses and probed by a high-order harmonic generation source, whose intrinsic flux instability was reduced by making use of a normalization procedure. This unconventional approach allowed us to perform measurements in a previously inaccessible range of phonon wavevectors within the Brillouin zone.
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63.20.-e Phonons in crystal lattices

Detection of particles of explosives via backward coherent anti-Stokes Raman spectroscopy

Alexander Portnov, Salman Rosenwaks, and Ilana Bar

Appl. Phys. Lett. 93, 041115 (2008); http://dx.doi.org/10.1063/1.2963981 (3 pages) | Cited 10 times

Online Publication Date: 31 July 2008

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Coherent anti-Stokes Raman scattering spectroscopy (CARS) was used for detection of solid particles of explosives and related compounds. The CARS spectra were recorded in the fingerprint region and were shown to exhibit the strong characteristic features of spontaneous Raman spectra of the respective compounds. This study demonstrates the applicability of narrowband backward-CARS spectroscopy for detection of explosives and specifically of its preference over spontaneous Raman scattering. This method has the potential to be applied to remote sensing of hazardous materials.
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78.30.-j Infrared and Raman spectra
82.33.Vx Reactions in flames, combustion, and explosions

Three dimensional micromachining inside a transparent material by single pulse femtosecond laser through a hologram

Masahiro Yamaji, Hayato Kawashima, Jun’ichi Suzuki, and Shuhei Tanaka

Appl. Phys. Lett. 93, 041116 (2008); http://dx.doi.org/10.1063/1.2965451 (3 pages) | Cited 12 times

Online Publication Date: 31 July 2008

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A basic pattern of a three dimensional (3D) photonic crystal, which consists of 16 capsule shaped elements in eight layers, is formed inside a silica glass using only a single pulse femtosecond laser through a computer generated hologram. The three parameters indispensable to the completely flexible 3D patterning, namely, “absolute position,” “relative position,” and “shape” of each element, are discussed on the basis of the measured optical axis elongation as functions of pulse duration and fluence.
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42.62.Cf Industrial applications
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.70.Qs Photonic bandgap materials
42.40.Jv Computer-generated holograms
81.20.Wk Machining, milling

Noncontact inspection technique for electrical failures in semiconductor devices using a laser terahertz emission microscope

Masatsugu Yamashita, Chiko Otani, Kodo Kawase, Kiyoshi Nikawa, and Masayoshi Tonouchi

Appl. Phys. Lett. 93, 041117 (2008); http://dx.doi.org/10.1063/1.2965810 (3 pages) | Cited 4 times

Online Publication Date: 31 July 2008

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We have proposed and demonstrated a novel technique for the noncontact inspection of electrical failures in semiconductor devices using a laser terahertz emission microscope. It was found that the waveforms of the terahertz pulses, emitted by exciting p-n junctions in semiconductor circuits with focused ultrafast laser pulses, depend on the interconnection structures of the circuits. We successfully distinguished damaged silicon metal-oxide-semiconductor field effect transistor circuits with disconnected wires from normal ones by comparing the images of terahertz emission amplitudes between a normal chip and a defective one.
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84.30.-r Electronic circuits

Lifetimes and Auger coefficients in type-II W interband cascade lasers

W. W. Bewley, J. R. Lindle, C. S. Kim, M. Kim, C. L. Canedy, I. Vurgaftman, and J. R. Meyer

Appl. Phys. Lett. 93, 041118 (2008); http://dx.doi.org/10.1063/1.2967730 (3 pages) | Cited 22 times

Online Publication Date: 31 July 2008

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Lifetimes and Auger coefficients for type-II W interband cascade lasers are deduced from correlations of the experimental threshold current densities and slope efficiencies with calculated threshold carrier densities and optical gains. The room-temperature Auger coefficients for a number of low-threshold devices emitting at wavelengths from 2.9 to 4.1 μm fall in the narrow range of (3–5)×10−28 cm6/s, which represents a much stronger suppression of Auger decay than was implied by most earlier experiments and theoretical projections. The Auger coefficient is nearly independent of the thicknesses and compositions of the layers in the W active region.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Terahertz generation in an actively controlled femtosecond enhancement cavity

M. Theuer, D. Molter, K. Maki, C. Otani, J. A. L’huillier, and R. Beigang

Appl. Phys. Lett. 93, 041119 (2008); http://dx.doi.org/10.1063/1.2966342 (3 pages) | Cited 5 times

Online Publication Date: 1 August 2008

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We report on terahertz generation by Cherenkov-type optical rectification in lithium niobate using an actively controlled femtosecond pumped enhancement cavity. In this way a much higher pump power is available inside the cavity and an increased terahertz output power is obtained. The advantages of terahertz generation in the Cherenkov geometry are verified by comparing it with other types of emitters by means of electro-optical detection as well as by bolometer measurements.
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07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
41.60.Bq Cherenkov radiation

In-line holography for the characterization of ultrafast laser filamentation in transparent media

D. G. Papazoglou and S. Tzortzakis

Appl. Phys. Lett. 93, 041120 (2008); http://dx.doi.org/10.1063/1.2968190 (3 pages) | Cited 16 times

Online Publication Date: 1 August 2008

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A powerful experimental method, based on holographic microscopy, is used to retrieve the spatiotemporal distribution of small (<10−3) refractive index perturbations induced by ultrafast laser pulses in transparent media. A numerical iterative wavefront propagation approach is used to accurately reconstruct both the phase and the amplitude of the perturbed probe beam wavefront, while Abel inversion recovers the exact three dimensional distribution of the perturbation. For demonstration, a laser filament induced plasma string in air is fully characterized.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.40.My Applications
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Highly stacked quantum-dot laser fabricated using a strain compensation technique

Kouichi Akahane, Naokatsu Yamamoto, and Masahiro Tsuchiya

Appl. Phys. Lett. 93, 041121 (2008); http://dx.doi.org/10.1063/1.2968211 (3 pages) | Cited 10 times

Online Publication Date: 1 August 2008

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We used a strain compensation technique to fabricate highly stacked InAs quantum-dot (QD) structures on InP(311)B substrates. We stacked 60 layers of InAs QDs without degrading the crystal quality and produced a structure with a total QD density of 4.73×1012/cm2. We then fabricated a broad area laser diode with a 30-layer stack of InAs QDs using conventional photolithography. The laser diode showed ground state lasing at 1.58 μm with a threshold current of 162 mA. The achievement of ground state lasing is due to the increase in QD density, which is a result of using the strain compensation technique.
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42.55.Px Semiconductor lasers; laser diodes
68.65.Hb Quantum dots (patterned in quantum wells)
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
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Electron temperature and density determination in a nonequilibrium laser induced plasma by means of self-reversed-line spectroscopy

D. Karabourniotis, M. Ribiere, and B. G. Cheron

Appl. Phys. Lett. 93, 041501 (2008); http://dx.doi.org/10.1063/1.2963472 (3 pages) | Cited 6 times

Online Publication Date: 31 July 2008

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A method is presented for determining excited-level temperature (Tp), electron temperature (Tel) and density (nel) by comparing a self-reversed line emitted from high electron-density plasma with the computed Stark-broadened line shape. These parameters are simultaneously determined from the analysis of a resonance line of aluminum emitted at delay times of 109 ns in the early plasma arising from the laser ablation of aluminum. Substantial deviation from excitation equilibrium is evident from the large difference in Tp ( ≈ 8900 K) and Tel ( ≥ 13500 K).
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52.25.-b Plasma properties
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.38.Mf Laser ablation

Modes in a pulse-modulated radio-frequency dielectric-barrier glow discharge

J. J. Shi, J. Zhang, G. Qiu, J. L. Walsh, and M. G. Kong

Appl. Phys. Lett. 93, 041502 (2008); http://dx.doi.org/10.1063/1.2965453 (3 pages) | Cited 12 times

Online Publication Date: 31 July 2008

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This letter reports an experimental study of a pulse-modulated radio-frequency dielectric-barrier discharge in atmospheric helium. By controlling the duty cycle at a modulation frequency of 10 and 100 kHz, the 13.56 MHz discharge is shown to operate in three different glow modes: the continuum mode, the discrete mode, and the transition mode. By investigating plasma ignition, residual electrons during power off are found to affect different glow modes. Duty cycle dependences of power density, gas temperature, optical emission intensities at 706 and 777 nm are used to capture clearly the characteristics of the three glow modes.
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52.80.Hc Glow; corona
52.80.Pi High-frequency and RF discharges
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.-b Plasma production and heating

Hyperthermal hydrogen atoms in argon-hydrogen atmospheric pressure microplasma jet

C. Oliveira, J. A. Souza Corrêa, M. P. Gomes, B. N. Sismanoglu, and J. Amorim

Appl. Phys. Lett. 93, 041503 (2008); http://dx.doi.org/10.1063/1.2967016 (3 pages) | Cited 16 times

Online Publication Date: 31 July 2008

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An argon-hydrogen atmospheric pressure microplasma jet was constructed for the treatment of materials. The microplasma jet device operating at 50 W produced long plasma jet of 30 mm with gas temperatures measured, using OH emissions, from 1600 to 2600 K as a function of distance. Excitation temperature was found to be from 7000 to 10 000 K. Through the analysis of Hα line broadening mechanisms, surprising hot hydrogen atoms H (n = 3) were found with temperatures ranging from 12 000 to 19 600 K.
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52.75.-d Plasma devices
52.25.Kn Thermodynamics of plasmas

High-density magnetohydrodynamic energy conversion in a high-temperature inert gas

Tomoyuki Murakami and Yoshihiro Okuno

Appl. Phys. Lett. 93, 041504 (2008); http://dx.doi.org/10.1063/1.2966371 (3 pages) | Cited 3 times

Online Publication Date: 1 August 2008

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We describe high-density magnetohydrodynamic (MHD) energy conversion in a high-temperature seed-free argon plasma, for which a compact disk-shaped Hall-type radial-flow MHD electrical power generator is used. The state of the MHD power-generating plasma changes with increasing total inflow temperature from 8200 to 9400 K; unstable behavior accompanied by the appearance of fine structures is transformed to a homogeneous and stable state. The attained enthalpy extraction efficiency is comparable to previous results using a conventional seeded gas. Furthermore, a high power output density is achieved even in relatively low-density magnetic flux.
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52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.25.Kn Thermodynamics of plasmas
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