APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

2 Apr 2007

Volume 90, Issue 14, Articles (14xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 90, 142110 (2007); http://dx.doi.org/10.1063/1.2720640 (3 pages)

M. T. Björk, O. Hayden, H. Schmid, H. Riel, and W. Riess
Enlarge Image | Read More
Page 1 of 6 Pages Next Page | Jump to Page
back to top
RSS Feeds

Coupling between long range surface plasmon polariton mode and dielectric waveguide mode

Fang Liu, Yi Rao, Yidong Huang, Wei Zhang, and Jiangde Peng

Appl. Phys. Lett. 90, 141101 (2007); http://dx.doi.org/10.1063/1.2719169 (3 pages) | Cited 20 times

Online Publication Date: 3 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Coupling of TM mode between long range surface plasmon polariton (LRSPP) mode and conventional dielectric waveguide mode is demonstrated numerically with finite element method. The characteristics of a hybrid coupler, which consists of the LRSPP waveguide and conventional single mode dielectric waveguide, are analyzed. The high efficient coupling shows a possible route for integrating the SPP device and conventional dielectric optical devices together and a method to excite LRSPP mode with dielectric waveguide. Because the coupling just occurs on TM mode, this kind of the hybrid coupler can be used as polarization mode splitter and combiner.
Show PACS
42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers

Observation of whispering-gallery modes in Si microdisks at room temperature

J. S. Xia, Y. Ikegami, K. Nemoto, and Y. Shiraki

Appl. Phys. Lett. 90, 141102 (2007); http://dx.doi.org/10.1063/1.2719225 (3 pages) | Cited 9 times

Online Publication Date: 3 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Whispering-gallery modes are observed at room temperature in silicon microdisk resonators fabricated on silicon-on-insulator substrates. Sharp luminescent peaks originating from the crystalline silicon film, corresponding to the whispering-gallery modes, are observed to change in microdisks with different diameters. Over 30 times enhancement of the photoluminescence from bulk silicon is observed due to the microdisk.
Show PACS
42.79.-e Optical elements, devices, and systems
78.55.Ap Elemental semiconductors

Air stable high resolution organic transistors by selective laser sintering of ink-jet printed metal nanoparticles

Seung H. Ko, Heng Pan, Costas P. Grigoropoulos, Christine K. Luscombe, Jean M. J. Fréchet, and Dimos Poulikakos

Appl. Phys. Lett. 90, 141103 (2007); http://dx.doi.org/10.1063/1.2719162 (3 pages) | Cited 40 times

Online Publication Date: 3 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A high resolution organic field effect transistor (OFET) fabrication process has been developed based on the selective laser sintering of ink-jet printed nanoparticle inks and the recent development of an air stable carboxylate-functionalized polythiophene semiconducting polymer. The entire fabrication and device characterization are performed at room temperature, ambient pressure, and air environment without using complex lithographic methods. This low temperature OFET fabrication process based on nanoparticle laser sintering has great potential for realizing inexpensive, large area flexible electronics on heat sensitive polymer substrates.
Show PACS
85.30.Tv Field effect devices
42.62.-b Laser applications

Enhancement of terahertz wave generation from laser induced plasma

Xu Xie, Jingzhou Xu, Jianming Dai, and X.-C. Zhang

Appl. Phys. Lett. 90, 141104 (2007); http://dx.doi.org/10.1063/1.2719165 (3 pages) | Cited 16 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is well known that air plasma induced by ultrashort laser pulses emits broadband terahertz waves. The authors report the study of terahertz wave generation from the laser induced plasma where there is a preexisting plasma background. When a laser beam from a Ti:sapphire amplifier is used to generate a terahertz wave, enhancement of the generation is observed if there is another laser beam creating a plasma background. The enhancement of the terahertz wave amplitude lasts hundreds of picoseconds after the preionized background is created, with a maximum enhancement up to 250% observed.
Show PACS
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.25.Jm Ionization of plasmas

Spectral characteristics in long-period fiber gratings with nonuniform symmetrically ring shaped coatings

Andrea Cusano, Domenico Paladino, Antonello Cutolo, Ignacio Del Villar, Ignacio R. Matias, and Francisco J. Arregui

Appl. Phys. Lett. 90, 141105 (2007); http://dx.doi.org/10.1063/1.2719631 (3 pages) | Cited 5 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this work, the spectral characteristics of nonuniform symmetrically ring shaped coatings deposited on long-period fiber gratings have been theoretically and experimentally investigated. Electrostatic self-assembling technique was used to deposit with fine control uniform azimuthally symmetric coatings at nanoscale level. UV laser micromachining operating at 193 nm was applied to selectively remove the coating with high spatial resolution on ring shaped geometry. Phase shift effects and multiple interference fringes have been observed for all the attenuation bands, strongly depending on the length of the uncoated region and the coating features (thickness and optical properties). The ability of the proposed structure to exhibit wavelength selective operation, combined with the effects of high refractive index coatings on the cladding modes distribution, provides a valid technological platform for the development of advanced photonic devices for sensing and telecommunication applications.
Show PACS
42.81.Wg Other fiber-optical devices
42.79.Dj Gratings
42.79.Wc Optical coatings
42.81.Bm Fabrication, cladding, and splicing
81.16.Dn Self-assembly
42.62.-b Laser applications

Single mode stimulated emission from prismlike gallium nitride submicron cavities

C.-M. Lai, H.-M. Wu, P.-C. Huang, S.-L. Wang, and L.-H. Peng

Appl. Phys. Lett. 90, 141106 (2007); http://dx.doi.org/10.1063/1.2720259 (3 pages) | Cited 5 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors report single mode stimulated emission from optical pumping of prismlike gallium nitride (GaN) with a side length of 0.75 μm. The cavities were formed by reaction-rate-limited photoetching that preserved the nonpolar {10math0} or {11math0} facets. They were characterized by an average quality factor above 103 and an equivalent facet reflectivity exceeding 98%, which allowed field amplification by repeated internal reflections in the transverse plane and field polarization along the c axis. Slight spectral blueshift (0.35 nm) and narrowing in linewidth ( ∼ 0.4 nm) were observed with increase of pump intensity. These observations manifested resonant coupling of the band edge emission to a single mode of the prismlike GaN cavity.
Show PACS
42.55.Sa Microcavity and microdisk lasers
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Narrow stripe-width, low-ridge high power quantum cascade lasers

A. Lyakh, P. Zory, D. Wasserman, G. Shu, C. Gmachl, M. D’Souza, D. Botez, and D. Bour

Appl. Phys. Lett. 90, 141107 (2007); http://dx.doi.org/10.1063/1.2720260 (3 pages) | Cited 4 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Narrow stripe-width, low-ridge quantum cascade lasers operating at 5.3 μm were fabricated from InP-based, metal-organic chemical-vapor-deposition-grown material. Maximum peak-pulsed output power of 12 W at 14 A was measured from a low-ridge laser with a high reflectivity coated back facet. Modeling shows that the lateral variation of the transverse conductivity is essential for an accurate description of the current spreading in these devices.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Slow-light enhancement of Beer-Lambert-Bouguer absorption

Niels Asger Mortensen and Sanshui Xiao

Appl. Phys. Lett. 90, 141108 (2007); http://dx.doi.org/10.1063/1.2720270 (3 pages) | Cited 34 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors theoretically show how slow light in an optofluidic environment facilitates enhanced light-matter interactions, by orders of magnitude. The proposed concept provides strong opportunities for improving existing miniaturized chemical absorbance cells for Beer-Lambert-Bouguer absorption measurements widely employed in analytical chemistry.
Show PACS
42.25.Bs Wave propagation, transmission and absorption
82.80.Dx Analytical methods involving electronic spectroscopy

Low-threshold terahertz Si:As laser

S. G. Pavlov, U. Böttger, H.-W. Hübers, R. Kh. Zhukavin, K. A. Kovalevsky, V. V. Tsyplenkov, V. N. Shastin, N. V. Abrosimov, and H. Riemann

Appl. Phys. Lett. 90, 141109 (2007); http://dx.doi.org/10.1063/1.2720271 (3 pages) | Cited 9 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical threshold of terahertz intracenter arsenic-doped silicon lasers has been reduced by two orders of magnitude by applying a compressive force to the laser crystal. The Si:As lasers were optically excited with radiation from a CO2 laser operating at a wavelength of 10.59 μm. The lowest threshold intensity of 8 kW/cm2 was realized at about 3×108 Pa stress applied along the [001] crystal axis. The uniaxial stress breaks the resonant interaction of electrons bound to donors with intervalley f phonons. This changes the upper laser state from 2p± to 2p0, lowers the laser threshold, and increases the output power.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Amplified spontaneous emission from cyano substituted oligo(p-phenylene vinylene) single crystal with very high photoluminescent efficiency

Weijie Xie, Yupeng Li, Feng Li, Fangzhong Shen, and Yuguang Ma

Appl. Phys. Lett. 90, 141110 (2007); http://dx.doi.org/10.1063/1.2720298 (3 pages) | Cited 19 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amplified spontaneous emission (ASE) from high-quality crystal of cyano substituted oligo(p-phenylene vinylene) with very high photoluminescent efficiency is observed. The full widths at half maximum of the narrowed spectra can reach 10 nm when the pumping energy is 50 μJ/pulse. The threshold for ASE is about 7.9 μJ/pulse corresponding to 39.5 kW/cm2, which is among the lowest values for organic crystals ever reported. The gain coefficient at the peak wavelength of ASE and loss coefficient caused by scattering are ∼ 33 and ∼ 3.9 cm−1, respectively.
Show PACS
42.55.Rz Doped-insulator lasers and other solid state lasers
78.45.+h Stimulated emission
78.55.Kz Solid organic materials

Single shot method for a quantitative spatially resolved investigation of the homogeneity of the birefringence of nonlinear optical crystals

L. K. Frieß, V. Wesemann, A. Robertson, and J. A. L’huillier

Appl. Phys. Lett. 90, 141111 (2007); http://dx.doi.org/10.1063/1.2720306 (3 pages)

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter reports on a single shot method for the spatially resolved investigation of the homogeneity of the birefringence of nonlinear optical crystals. Using the same method the wavelength acceptance and the wavelength for phase-matched second harmonic generation are measured. The method is based on a single shot measurement of the sinc2 wavelength dependence of the second harmonic conversion efficiency. This dependence is detected by converting the broad spectrum of femtosecond-laser pulses generated by a Ti:sapphire laser. The spatial resolution of these measurements is 80 μm. The accuracy exceeds 2.5% for the determination of the homogeneity of the birefringence.
Show PACS
42.70.Mp Nonlinear optical crystals
78.20.Fm Birefringence
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Hole-initiated multiplication in back-illuminated GaN avalanche photodiodes

R. McClintock, J. L. Pau, K. Minder, C. Bayram, P. Kung, and M. Razeghi

Appl. Phys. Lett. 90, 141112 (2007); http://dx.doi.org/10.1063/1.2720712 (3 pages) | Cited 21 times

Online Publication Date: 6 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Avalanche p-i-n photodiodes were fabricated on AlN templates for back illumination. Structures with different intrinsic layer thicknesses were tested. A critical electric field of 2.73 MV/cm was estimated from the variation of the breakdown voltage with thickness. From the device response under back and front illumination and the consequent selective injection of holes and electrons in the junction, ionization coefficients were obtained for GaN. The hole ionization coefficient was found to be higher than the electron ionization coefficient as predicted by theory. Excess multiplication noise factors were also calculated for back and front illumination, and indicated a higher noise contribution for electron injection.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.Kk Junction diodes
85.30.De Semiconductor-device characterization, design, and modeling

Simple microscope using a compound refractive lens and a wide-bandwidth thermal neutron beam

J. T. Cremer, H. Park, M. A. Piestrup, C. K. Gary, R. H. Pantell, R. G. Flocchini, H. P. Egbert, M. D. Kloh, and R. B. Walker

Appl. Phys. Lett. 90, 141113 (2007); http://dx.doi.org/10.1063/1.2719155 (3 pages) | Cited 3 times

Online Publication Date: 6 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The results of imaging experiments using biconcave, spherical compound refractive lenses (CRLs) and a wide-bandwidth thermal neutron beam are presented. Two CRLs were used, consisting of 155 beryllium and 120 copper lenses. The experiments were performed using a thermal neutron beam line at McClellan Nuclear Radiation Center reactor. The authors obtained micrographs of cadmium slits with up to 5× magnification and 0.3 mm resolution. The CRL resolution was superior to a pinhole camera with the same aperture diameter. The modulation transfer function (MTF) of the CRL was calculated and compared with the measured MTF at five spatial frequencies, showing good agreement.
Show PACS
07.60.Pb Conventional optical microscopes
42.79.Bh Lenses, prisms and mirrors
03.75.Be Atom and neutron optics
42.30.Lr Modulation and optical transfer functions

Small optical volume terahertz emitting microdisk quantum cascade lasers

L. Andrea Dunbar, Romuald Houdré, Giacomo Scalari, Lorenzo Sirigu, Marcella Giovannini, and Jérôme Faist

Appl. Phys. Lett. 90, 141114 (2007); http://dx.doi.org/10.1063/1.2719674 (3 pages) | Cited 27 times

Online Publication Date: 6 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors fabricate and characterize a series of quantum cascade laser micropillars emitting at ≈ 3.5 THz. The optical confinement by double plasmon guiding in the vertical direction creates a large impedance mismatch between the confined optical modes and free space. Thus, unlike standard dielectric structures, large quality (Q) factors are maintained for small radius to wavelength ratios. The narrow bandwidth of the optical mode results in low threshold current (8 mA) single-mode lasers. Cavity pulling enables a fine dynamic tuning of the emission wavelength. Comparison of the frequency shift due to cavity pulling and the Stark effect provides an experimental measure of the gain (36 cm−1).
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.55.Sa Microcavity and microdisk lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking

Distributed Bragg reflector consisting of high- and low-refractive-index thin film layers made of the same material

Martin F. Schubert, J.-Q. Xi, Jong Kyu Kim, and E. Fred Schubert

Appl. Phys. Lett. 90, 141115 (2007); http://dx.doi.org/10.1063/1.2720269 (3 pages) | Cited 29 times

Online Publication Date: 6 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A conductive distributed Bragg reflector (DBR) composed entirely of a single material—indium tin oxide (ITO)—is reported. The high- and low-refractive-index layers of the DBR are deposited by oblique-angle deposition and consist of ITO thin films with low and high porosities, which yield an index contrast of Δn = 0.4. A single-material DBR with three periods achieves a reflectivity of 72.7%, in excellent agreement with theory.
Show PACS
42.82.Gw Other integrated-optical elements and systems
42.79.Bh Lenses, prisms and mirrors
42.82.Cr Fabrication techniques; lithography, pattern transfer

Broadband coherent anti-Stokes Raman scattering spectroscopy in supercontinuum optical trap

Kebin Shi, Peng Li, and Zhiwen Liu

Appl. Phys. Lett. 90, 141116 (2007); http://dx.doi.org/10.1063/1.2720295 (3 pages) | Cited 14 times

Online Publication Date: 6 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors report on a supercontinuum tweezer which combines tweezing with broadband ( ∼ 3000 cm−1) coherent anti-Stokes Raman scattering (CARS) spectroscopy by taking advantage of the high spatial coherence and broad bandwidth of pulsed supercontinuum generated in a nonlinear photonic crystal fiber. Polarization-discriminated and time-resolved CARS is investigated to suppress the nonresonant four-wave-mixing background.
Show PACS
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
37.10.Vz Mechanical effects of light on atoms, molecules, and ions
42.70.Qs Photonic bandgap materials
42.81.-i Fiber optics
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
back to top
RSS Feeds

Twin injection-needle plasmas at atmospheric pressure

Yong Cheol Hong, Soon Chon Cho, and Han Sup Uhm

Appl. Phys. Lett. 90, 141501 (2007); http://dx.doi.org/10.1063/1.2718483 (3 pages) | Cited 10 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Twin injection-needle plasmas at atmospheric pressure are introduced as low-temperature nonequilibrium plasma source. The plasmas with long plasma columns of about 55 cm are produced from one alternating current (ac) power supply as if each of the plasmas is a fraternal twin and shows different characteristics in plasma column length and gas temperature. The twin plasma columns are regarded as skinny rods with a uniform charge distribution, and the change of the plasma column lengths with different distances between the plasmas is compared with the change of the capacitance of the skinny rods presented as a model.
Show PACS
52.50.Dg Plasma sources
52.25.Fi Transport properties
52.70.Ds Electric and magnetic measurements

Hot ion generation from nanostructured surfaces under intense femtosecond laser irradiation

S. Bagchi, P. Prem Kiran, M. K. Bhuyan, S. Bose, P. Ayyub, M. Krishnamurthy, and G. Ravindra Kumar

Appl. Phys. Lett. 90, 141502 (2007); http://dx.doi.org/10.1063/1.2715108 (3 pages) | Cited 9 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Studies of ion emission from nanostructured metallic surfaces excited by intense (0.5–6.3×1016 W cm−2) 50 fs laser demonstrate that “hotter” electrons need not to give rise hotter ions, contrary to conventional expectation. Such surfaces produce twice as many ions as planar surfaces in the moderate energy regime (16–75 keV), but their yield in the higher energy range (75–2000 keV) is substantially lower. Surface modulations also influence ion beam divergence.
Show PACS
79.20.Ds Laser-beam impact phenomena
68.47.De Metallic surfaces
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Bg Metals and alloys
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Two-dimensional space-charge-limited flows in a crossed-field gap

W. S. Koh and L. K. Ang

Appl. Phys. Lett. 90, 141503 (2007); http://dx.doi.org/10.1063/1.2720710 (3 pages) | Cited 1 time

Online Publication Date: 6 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter presents a two-dimensional (2D) model of space-charge-limited current in a planar crossed-field gap with a magnetic strength of B/BH = 0–3, where BH is the Hull cutoff magnetic field. The electrons are emitted from an infinite length strip of finite width W comparable to the gap spacing D. It is found that the 2D enhancement of the crossed-field limiting current is 1+F×4D/(πW), where F ( = 0.05–0.5) is a normalized mean-position factor, and it is a function of B/BH. Good agreement has been obtained in comparisons with particle-in-cell simulation.
Show PACS
52.59.Sa Space-charge-dominated beams
52.40.Mj Particle beam interactions in plasmas
52.25.Fi Transport properties
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.65.Rr Particle-in-cell method
back to top
RSS Feeds

Nd3+ ion shift under domain inversion by electron beam writing in LiNbO3

P. Molina, D. Sarkar, M. O. Ramírez, J. García Solé, L. E. Bausá, B. J. García, and J. E. Muñoz Santiuste

Appl. Phys. Lett. 90, 141901 (2007); http://dx.doi.org/10.1063/1.2719036 (3 pages) | Cited 8 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ferroelectric domain inversion has been obtained in Nd3+ doped lithium niobate by means of direct electron beam writing. The local effects of the polarization inversion on the optical transitions of Nd3+ ions have been studied by low temperature high resolution site selective spectroscopy. Inverted regions present different axial crystal field acting over Nd3+ ions compared with noninverted (original) regions. The results can be interpreted in terms of slight shifts of Nd3+ ions along the ferroelectric c axis within the Li+ octahedrons, as a result of the lattice rearrangement after the domain inversion processes.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
77.22.Ej Polarization and depolarization
61.80.Fe Electron and positron radiation effects
78.30.Hv Other nonmetallic inorganics

Evidence for segregation of Te in Ge2Sb2Te5 films: Effect on the “phase-change” stress

L. Krusin-Elbaum, C. Cabral, Jr., K. N. Chen, M. Copel, D. W. Abraham, K. B. Reuter, S. M. Rossnagel, J. Bruley, and V. R. Deline

Appl. Phys. Lett. 90, 141902 (2007); http://dx.doi.org/10.1063/1.2719148 (3 pages) | Cited 40 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors present direct evidence for Te segregation to the grain boundaries in chalcogenide Ge2Sb2Te5 films by using transmission electron microscopy scans with a 0.5 nm diameter focused probe. This finding is consistent with the observed impeded grain growth and with the post-transition relief of a “spikelike” stress, fully to the pretransition level. Te motion shows up in void formation below 200 °C, a pileup of Te at the surface and its loss at higher (above 400 °C) temperatures. Tuning the driving force for this segregation may be key for the optimal phase-change material design.
Show PACS
64.75.-g Phase equilibria
68.35.Dv Composition, segregation; defects and impurities
81.30.Mh Solid-phase precipitation
61.72.Mm Grain and twin boundaries
68.60.Bs Mechanical and acoustical properties
68.35.Gy Mechanical properties; surface strains

Recombination dynamics of excitons in Mg0.11Zn0.89O alloy films grown using the high-temperature-annealed self-buffer layer by laser-assisted molecular-beam epitaxy

Masashi Kubota, Takeyoshi Onuma, Atsushi Tsukazaki, Akira Ohtomo, Masashi Kawasaki, Takayuki Sota, and Shigefusa F. Chichibu

Appl. Phys. Lett. 90, 141903 (2007); http://dx.doi.org/10.1063/1.2719168 (3 pages) | Cited 9 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Recombination dynamics of excitons in Mg0.11Zn0.89O epilayers grown by laser-assisted molecular-beam epitaxy on a ScAlMgO4 substrate were investigated. By using the MgZnO high-temperature-annealed self-buffer layer (HITAB), the value of full width at half maximum of the near-band-edge (NBE) photoluminescence (PL) peak at 3.6 eV was decreased from 133 to 94 meV at 293 K, and the intensity ratio of the NBE emission to the deep emission band centered around 2.2 eV was increased by a factor of 3. Also, the PL lifetime of the NBE peak at 293 K under the excitation density of 1 μJ/cm2 was increased from 49 to 60 ps. These results suggest that HITAB gave rise to improved alloy compositional homogeneity and reduced concentration of point defects.
Show PACS
81.05.Dz II-VI semiconductors
71.35.-y Excitons and related phenomena
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ga II-VI semiconductors
78.55.Et II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Dehydrogenation from 3d-transition-metal-doped NaAlH4: Prediction of catalysts

A. Blomqvist, C. Moysés Araújo, P. Jena, and R. Ahuja

Appl. Phys. Lett. 90, 141904 (2007); http://dx.doi.org/10.1063/1.2719244 (3 pages) | Cited 10 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A fundamental understanding of the role of catalysts in improving the kinetics and thermodynamics of hydrogen sorption in NaAlH4 is the key for using this material in hydrogen storage. The authors present a systematic theoretical study of energies needed to desorb hydrogen in 3d transition metal (Sc–Cu)-doped NaAlH4. They show that Cr and Fe atoms can be far more effective catalysts than Ti in desorbing hydrogen. The role of the 3d metal atoms in improving the thermodynamics of dehydrogenation is attributed to a significant shortening of the bond length with neighboring Al atoms.
Show PACS
68.43.Mn Adsorption kinetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
65.40.G- Other thermodynamical quantities
84.60.-h Direct energy conversion and storage

Vapor pressure critical amplitudes from the normal boiling point

S. Velasco, F. L. Román, J. A. White, and A. Mulero

Appl. Phys. Lett. 90, 141905 (2007); http://dx.doi.org/10.1063/1.2719642 (3 pages) | Cited 3 times

Online Publication Date: 4 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors propose a method to estimate the two first critical amplitudes for the vapor pressure of a fluid in terms only of the reduced pressure, Pbr = Pb/Pc, and temperature, Tbr = Tb/Tc, of the normal boiling point. The method is based on the fact that the product (1−Tr)Pr presents a maximum near the critical region. Based on a study of 43 fluids, the authors found that the reduced pressure and temperature of that maximum can be obtained from simple relations in terms of the parameter h ≡ Tbr ln Pbr/(Tbr−1). These relations are checked against additional data for 1608 fluids.
Show PACS
64.70.F- Liquid-vapor transitions

Photoluminescence study of semipolar {10math1} InGaN/GaN multiple quantum wells grown by selective area epitaxy

Hongbo Yu, L. K. Lee, Taeil Jung, and P. C. Ku

Appl. Phys. Lett. 90, 141906 (2007); http://dx.doi.org/10.1063/1.2720302 (3 pages) | Cited 14 times

Online Publication Date: 5 April 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Semipolar InGaN/GaN multiple quantum wells (MQWs) were fabricated on the {10math1} facets of GaN pyramidal structures by selective area epitaxy. Optical properties of the MQWs were investigated by photoluminescence (PL) in comparison with (0001) MQWs. Compared with (0001) MQWs, the internal electric field in the {10math1} MQWs was remarkably reduced, the PL peak redshifted monotonically with the increasing temperature, and the internal quantum efficiency was estimated to be improved by a factor of 3. These results suggest that the {10math1} planes are promising for improving the performance of III-nitride light emitters owing to their surface stability and suppression of polarization effects.
Show PACS
78.67.De Quantum wells
78.55.Cr III-V semiconductors
68.65.Fg Quantum wells
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
Page 1 of 6 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close