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2 Nov 2009

Volume 95, Issue 18, Articles (18xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 95, 183504 (2009); http://dx.doi.org/10.1063/1.3256223 (3 pages)

Hoon-Sik Kim, Sang Min Won, Young-Geun Ha, Jong-Hyun Ahn, Antonio Facchetti, Tobin J. Marks, and John A. Rogers
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Electrically tunable terahertz quantum-cascade laser with a heterogeneous active region

Suraj P. Khanna, Mohammed Salih, Paul Dean, A. Giles Davies, and Edmund H. Linfield

Appl. Phys. Lett. 95, 181101 (2009); http://dx.doi.org/10.1063/1.3253714 (3 pages) | Cited 10 times

Online Publication Date: 2 November 2009

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We demonstrate experimentally a terahertz frequency quantum-cascade laser which can be tuned electronically, in a step-wise manner from typically 3.07 to 3.40 THz, by changing the applied electric field across the device. To achieve this, the gallium growth rate was successively reduced during growth of the active region from +6% to −4% of its nominal 1 μm/h operating value. This produced a heterogeneous active region, comprising 23 sections of different lasing units stacked together. With a single-metal surface-plasmon waveguide configuration, the devices operated in pulsed mode, up to a temperature of 81 K, and gave peak powers of ∼ 8 mW.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking
42.79.Gn Optical waveguides and couplers
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Thermal-induced refractive-index planar waveguide laser

Hongxiang Kang (康宏向), Haitao Zhang (张海涛), and Dongsheng Wang (王东生)

Appl. Phys. Lett. 95, 181102 (2009); http://dx.doi.org/10.1063/1.3258068 (3 pages) | Cited 1 time

Online Publication Date: 2 November 2009

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The feasibility of a thermal-induced refractive-index planar waveguide laser was demonstrated. The condition for the guided modes to be confined in the gain region was calculated. A thermal-induced refractive-index planar waveguide laser was made simply by pumping a thin center layer of a slab crystal and its modes can be controlled by the thermal input unit area and the pumped region width. An output power of 23.1 W with an optical to optical conversion efficiency of 46% was obtained. A thermal-induced refractive-index planar waveguide laser is very promising for efficient and bright laser sources due to its simple waveguide structure.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.72.-g Optical sources and standards
42.82.Et Waveguides, couplers, and arrays

Near-field imaging of femtosecond laser ablated sub-λ/4 holes in lithium niobate

Airán Ródenas, Jorge Lamela, Daniel Jaque, Ginés Lifante, Francisco Jaque, Antonio García-Martín, Guangyong Zhou, and Min Gu

Appl. Phys. Lett. 95, 181103 (2009); http://dx.doi.org/10.1063/1.3256219 (3 pages) | Cited 3 times

Online Publication Date: 2 November 2009

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We report on the direct femtosecond laser ablation of sub-λ/4 (80–250 nm) holes in LiNbO3 crystals and on its local near-field imaging. We show that the near-field transmission of holes can feature an attenuation of ∼ 75% at hole central position, and a ∼ 20% transmission enhancement at its sides. This high-contrast ring-shaped near-field distribution is found to be in agreement with simulations, suggesting the surface relief as the main contrast mechanism.
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52.38.Mf Laser ablation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Optical position clamping with predictive control

Heikki Ojala, Anders Korsbäck, Anders E. Wallin, and Edward Hæggström

Appl. Phys. Lett. 95, 181104 (2009); http://dx.doi.org/10.1063/1.3257693 (3 pages) | Cited 2 times

Online Publication Date: 4 November 2009

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We increase the effective stiffness of optical tweezers by position clamping a polystyrene bead with a predictive feedback control algorithm. This algorithm mitigates the effect of feedback loop delay. Hence, higher gain than with proportional control can be employed, which results in higher effective trap stiffness, without trap instability. In experiments (initial trap stiffness 0.056 pN/nm with a 1.78 μm diameter polystyrene bead), predictive control increased the effective trap stiffness by 55% relative to proportional control. We also derive theoretical expressions for the power spectra of the bead position controlled by our algorithm.
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07.05.Dz Control systems

Flexible metamaterials for wireless strain sensing

Rohat Melik, Emre Unal, Nihan Kosku Perkgoz, Christian Puttlitz, and Hilmi Volkan Demir

Appl. Phys. Lett. 95, 181105 (2009); http://dx.doi.org/10.1063/1.3250175 (3 pages) | Cited 14 times

Online Publication Date: 4 November 2009

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We proposed and demonstrated flexible metamaterial-based wireless strain sensors that include arrays of split ring resonators (SRRs) to telemetrically measure strain. For these metamaterial sensors, we showed that a flexible substrate (e.g., Kapton tape) delivers greater sensitivity and a more linear response as compared to using silicon substrates. Specifically, these tape-based flexible SRR sensors exhibit a significantly improved sensitivity level of 0.292 MHz/kgf with a substantially reduced nonlinearity error of 3% for externally applied mechanical loads up to 250 kgf. These data represent a sixfold increase in sensitivity and a 16-fold reduction in error percentage.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.10.Pz Instruments for strain, force, and torque

Controlling the spectrum of x-rays generated in a laser-plasma accelerator by tailoring the laser wavefront

S. P. D. Mangles, G. Genoud, S. Kneip, M. Burza, K. Cassou, B. Cros, N. P. Dover, C. Kamperidis, Z. Najmudin, A. Persson, J. Schreiber, F. Wojda, and C.-G. Wahlström

Appl. Phys. Lett. 95, 181106 (2009); http://dx.doi.org/10.1063/1.3258022 (3 pages) | Cited 11 times

Online Publication Date: 4 November 2009

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By tailoring the wavefront of the laser pulse used in a laser-wakefield accelerator, we show that the properties of the x-rays produced due to the electron beam’s betatron oscillations in the plasma can be controlled. By creating a wavefront with coma, we find that the critical energy of the synchrotronlike x-ray spectrum can be significantly increased. The coma does not substantially change the energy of the electron beam, but does increase its divergence and produces an energy-dependent exit angle, indicating that changes in the x-ray spectrum are due to an increase in the electron beam's oscillation amplitude within the wakefield.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.59.Px Hard X-ray sources
52.38.Kd Laser-plasma acceleration of electrons and ions

Bistable twisted-bend and twisted-nematic liquid crystal display

Y. W. Li and H. S. Kwok

Appl. Phys. Lett. 95, 181107 (2009); http://dx.doi.org/10.1063/1.3254212 (3 pages) | Cited 1 time

Online Publication Date: 5 November 2009

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Bistability of twisted-bend and twisted configuration is found. It is based on the elastic and topological inequivalency of director orientation. Multiple states of minimum local energy exist, with appropriate boundary conditions. The effects of elastic constants, d/P ratio and pretilt angle are also investigated. Fast electrical switching time <500 μs and high average contrast of 45:1 are obtained experimentally.
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42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems

Ultrafast imaging of photoelectron packets generated from graphite surface

Ramani K. Raman, Zhensheng Tao, Tzong-Ru Han, and Chong-Yu Ruan

Appl. Phys. Lett. 95, 181108 (2009); http://dx.doi.org/10.1063/1.3259779 (3 pages) | Cited 5 times

Online Publication Date: 5 November 2009

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We present an electron projection imaging method to study the ultrafast evolution of photoelectron density distribution and transient fields near the surface. The dynamical profile of the photoelectrons from graphite reveals an origin of a thermionic emission, followed by an adiabatic process leading to electron acceleration and cooling before a freely expanding cloud is established. The hot electron emission is found to couple with a surface charge dipole layer formation, with a sheet density several orders of magnitude higher than that of the vacuum emitted cloud.
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78.47.J- Ultrafast spectroscopy (<1 psec)
79.60.Bm Clean metal, semiconductor, and insulator surfaces
72.20.Ht High-field and nonlinear effects
79.40.+z Thermionic emission
72.80.Sk Insulators

Engineering single photon emitters by ion implantation in diamond

B. Naydenov, R. Kolesov, A. Batalov, J. Meijer, S. Pezzagna, D. Rogalla, F. Jelezko, and J. Wrachtrup

Appl. Phys. Lett. 95, 181109 (2009); http://dx.doi.org/10.1063/1.3257976 (3 pages) | Cited 9 times

Online Publication Date: 5 November 2009

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Diamond provides unique technological platform for quantum technologies including quantum computing and communication. Controlled fabrication of optically active defects is a key element for such quantum toolkit. Here we report the production of single color centers emitting in the blue spectral region by high energy implantation of carbon ions. We demonstrate that single implanted defects show sub-poissonian statistics of the emitted photons and can be explored as single photon source in quantum cryptography. Strong zero phonon line at 470.5 nm allows unambiguous identification of this defect as interstitial-related TR12 color center.
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61.72.jn Color centers
61.72.up Other materials
63.20.-e Phonons in crystal lattices
61.72.jj Interstitials

Polarization entanglement with graded-index lenses

Giuseppe Vallone, Gaia Donati, Francesco De Martini, and Paolo Mataloni

Appl. Phys. Lett. 95, 181110 (2009); http://dx.doi.org/10.1063/1.3257376 (3 pages) | Cited 2 times

Online Publication Date: 6 November 2009

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By using an optical device based on the integration of a graded-index (GRIN) rod lens and a single-mode optical fiber we efficiently collected photon pairs generated by spontaneous parametric down-conversion. We show that this system preserves the polarization entanglement of the two-photon states. Hence this device, characterized by a remarkable easiness of alignment and allowing for high coupling efficiency of single-mode radiation, can be used with photons entangled in various degrees of freedom, such as polarization and spatial momentum and to interconnect different sides of complex optical circuits.
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42.79.Bh Lenses, prisms and mirrors
42.79.Ry Gradient-index (GRIN) devices

Birefringence-induced mode-dependent tuning of liquid crystal infiltrated InGaAsP photonic crystal nanocavities

M. A. Dündar, H. H. J. E. Kicken, A. Yu. Silov, R. Nötzel, F. Karouta, H. W. M. Salemink, and R. W. van der Heijden

Appl. Phys. Lett. 95, 181111 (2009); http://dx.doi.org/10.1063/1.3259814 (3 pages) | Cited 8 times

Online Publication Date: 6 November 2009

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Mode-dependent shifts of resonant frequencies of cavities in liquid crystal (LC) infiltrated planar photonic crystals (PhC) are experimentally observed when the temperature is varied across the LC ordering transition. The shifts can be in opposite directions, even for two very similar nearly degenerate modes. The behavior is attributed to the different interactions of the modes with the two components of the refractive index of the LC infill and directly demonstrates that at least a substantial amount of the LC is oriented perpendicular to the PhC-hole axis.
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78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.20.Fm Birefringence
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.70.Qs Photonic bandgap materials

Effect of polarization on spectral switches in the diffraction of stochastic electromagnetic beams

Liuzhan Pan, Zhiguo Zhao, Chaoliang Ding, and Baida Lü

Appl. Phys. Lett. 95, 181112 (2009); http://dx.doi.org/10.1063/1.3259824 (3 pages) | Cited 4 times

Online Publication Date: 6 November 2009

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We consider the stochastic electromagnetic Gaussian Schell-model (EGSM) beam and show that the polarization of stochastic electromagnetic EGSM beams in the source plane affect spectral switches of diffracted stochastic electromagnetic EGSM beams in the far field. For two cases of fully coherent and partially coherent δxx = δyy the behavior of spectral switches are same in different degrees of polarization of the source.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects

Microbubble-enhanced ultrasound-modulated fluorescence in a turbid medium

Baohong Yuan, Yuan Liu, Patrick M. Mehl, and Joseph Vignola

Appl. Phys. Lett. 95, 181113 (2009); http://dx.doi.org/10.1063/1.3262959 (3 pages) | Cited 9 times

Online Publication Date: 6 November 2009

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The feasibility of using ultrasound to modulate fluorescence in a turbid medium is still in debate due to the difficulty of detecting the modulated signal. We have demonstrated a system that could detect the weak signals of ultrasound-modulated fluorescence (UMF) by using a broadband lock-in amplifier and microbubbles as enhancement agents. By detecting the microbubble-enhanced UMF signal, a sub-millimeter fluorescent tube submerged in a turbid medium with a depth of 2 cm has been clearly observed with an ultrasonic spatial resolution. The modulation efficiency was significantly improved by using microbubbles, and was found to linearly increase with the drive voltage applied to the ultrasound transducer and the fluorophore concentration within the range adopted in this study. Possible modulation mechanisms are discussed.
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87.63.dh Ultrasonographic imaging
87.64.kv Fluorescence
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A simple atmospheric pressure room-temperature air plasma needle device for biomedical applications

X. Lu, Z. Xiong, F. Zhao, Y. Xian, Q. Xiong, W. Gong, C. Zou, Z. Jiang, and Y. Pan

Appl. Phys. Lett. 95, 181501 (2009); http://dx.doi.org/10.1063/1.3258071 (3 pages) | Cited 32 times

Online Publication Date: 2 November 2009

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Rather than using noble gas, room air is used as the working gas for an atmospheric pressure room-temperature plasma. The plasma is driven by submicrosecond pulsed directed current voltages. Several current spikes appear periodically for each voltage pulse. The first current spike has a peak value of more than 1.5 A with a pulse width of about 10 ns. Emission spectra show that besides excited OH, O, N2(C–B), and N2+(B–X) emission, excited NO, N2(B–A), H, and even N emission are also observed in the plasma, which indicates that the plasma may be more reactive than that generated by other plasma jet devices. Utilizing the room-temperature plasma, preliminary inactivation experiments show that Enterococcus faecalis can be killed with a treatment time of only several seconds.
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52.75.-d Plasma devices
87.85.-d Biomedical engineering

Evolution of laser-induced carbon particle breakdown in gas

Hong-Yu Chu and Man-Chon Si

Appl. Phys. Lett. 95, 181502 (2009); http://dx.doi.org/10.1063/1.3258493 (3 pages) | Cited 2 times

Online Publication Date: 3 November 2009

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We investigate the evolution of the laser-induced breakdown of a suspended micrometer-sized carbon particle at 460 torr N2 gas environment. An elliptical hot gas resulting from the ionizations of the particle breakdown and the gas breakdown is observed. We show that the deformation of the elliptical gas starts from the vertical direction and the counterpropagating flows leads to a protruding tail at later stage. The rarefaction wave is suspected to be responsible for the deformation of the gas core and the formation of the vortex ring structure, which is different from the previous laser-induced gas breakdown investigations.
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51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)

Hot and super-hot hydrogen atoms in microwave plasma

E. Tatarova, E. Felizardo, F. M. Dias, M. Lino da Silva, C. M. Ferreira, and B. Gordiets

Appl. Phys. Lett. 95, 181503 (2009); http://dx.doi.org/10.1063/1.3259658 (3 pages) | Cited 4 times

Online Publication Date: 5 November 2009

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“Super-hot” (kinetic energy ∼ 4–8 eV) and “hot” (kinetic energy ∼ 0.3 eV) H atoms were detected in a surface wave (500 MHz) generated H2 plasma column, at pressure p = 0.01 mbar, from the analysis of the Hβ, Hγ, Hδ, and Hε emission line profiles. These profiles were found to evolve from single Gaussian to bi-Gaussian toward the plasma column end. Population inversion between the levels 5→4 and 6→4 was detected. At pressure p = 0.2 mbar, super-hot atoms were not detected and the temperature of the hot atoms was found to increase with the upper level principal quantum number.
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32.80.Xx Level crossing and optical pumping
52.80.Pi High-frequency and RF discharges
52.35.-g Waves, oscillations, and instabilities in plasmas and intense beams

Enhancement of electric force by ion-neutral collisions

G. Makrinich and A. Fruchtman

Appl. Phys. Lett. 95, 181504 (2009); http://dx.doi.org/10.1063/1.3257694 (3 pages) | Cited 5 times

Online Publication Date: 5 November 2009

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The measured force exerted on an ion flow by an electric field is found to be larger than the electric force that can be exerted if the ions are collisionless. In addition, the increase of the gas pressure is found to result in an increase of the electric force despite a simultaneous decrease of the deposited electric power. Employing a simple model, we argue that these experimental findings result from the electric force being felt by the ions for a longer time, their residence time in the acceleration region is increased due to their slowing-down collisions with neutrals.
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52.20.Hv Atomic, molecular, ion, and heavy-particle collisions
52.30.-q Plasma dynamics and flow

Terahertz vacuum electronic circuits fabricated by UV lithographic molding and deep reactive ion etching

Young-Min Shin, Larry R. Barnett, Diana Gamzina, Neville C. Luhmann, Jr., Mark Field, and Robert Borwick

Appl. Phys. Lett. 95, 181505 (2009); http://dx.doi.org/10.1063/1.3259823 (3 pages) | Cited 9 times

Online Publication Date: 6 November 2009

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The 0.22 THz vacuum electronic circuits fabricated by UV lithography molding and deep reactive ion etching processes are under investigation for submillimeter wave applications. Eigenmode transient simulations show that, accounting for realistic values of our currently achievable fabrication tolerances, the transmission, and dispersion properties of the operation modes of a TE-mode, staggered, double grating circuit are maintained within less than 1 dB and 2% deviation, respectively. Scanning electron microscopy and atomic force microscopy analyses of the fabricated circuit samples demonstrate that both of the microelectromechanical system fabrication approaches produce circuits with ±3–5 μm dimensional tolerance and ∼ 30 nm surface roughness.
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85.45.-w Vacuum microelectronics
81.16.-c Methods of micro- and nanofabrication and processing
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning

Purified Si film formation from metallurgical-grade Si by hydrogen plasma induced chemical transport

Hiromasa Ohmi, Akihiro Goto, Daiki Kamada, Yoshinori Hamaoka, Hiroaki Kakiuchi, and Kiyoshi Yasutake

Appl. Phys. Lett. 95, 181506 (2009); http://dx.doi.org/10.1063/1.3261751 (3 pages) | Cited 3 times

Online Publication Date: 6 November 2009

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Purified Si film is prepared directly from metallurgical-grade Si (MG-Si) by using hydrogen plasma induced chemical transport at subatmospheric pressure. The purification mechanism is based on the different hydrogenation behaviors of the various impurity elements in MG-Si. The prepared Si films clearly had fewer typical metal impurities (Fe, Al, Ti, Cr, Mn, etc.) than those in the MG-Si. In particular, the Fe concentration was drastically reduced from 6900 mass ppm to less than 0.1 mass ppm by one time chemical transport. Furthermore, metal impurity concentrations were further reduced by repeating chemical transport deposition.
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68.55.ag Semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
52.77.Dq Plasma-based ion implantation and deposition
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.05.Cy Elemental semiconductors
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Broadband planar Luneburg lens based on complementary metamaterials

Qiang Cheng, Hui Feng Ma, and Tie Jun Cui

Appl. Phys. Lett. 95, 181901 (2009); http://dx.doi.org/10.1063/1.3257375 (3 pages) | Cited 8 times

Online Publication Date: 2 November 2009

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A two-dimensional broadband low-loss Luneburg lens has been designed based on the complementary metamaterials. The complementary I-shaped unit has been chosen as the basic cell due to its high resonant frequency, whose effective constitutive parameters are nearly constants at low frequencies. Numerical simulations are performed to determine the relationship between the unit geometry and the refraction index. The experimental sample has been fabricated and tested in a two-dimensional near-field microwave scanning apparatus, where the experiment and simulation results agree very well. Good focusing ability has been shown from the measured field distributions of the designed planar Luneburg lens.
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84.40.-x Radiowave and microwave (including millimeter wave) technology

Kinetics of a transient silicide during the reaction of Ni thin film with (100)Si

Dominique Mangelinck, Khalid Hoummada, and Ivan Blum

Appl. Phys. Lett. 95, 181902 (2009); http://dx.doi.org/10.1063/1.3257732 (3 pages) | Cited 8 times

Online Publication Date: 2 November 2009

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In situ measurements of the kinetics of the transient θ-Ni2Si phase formation have been obtained by x-ray diffraction and differential scanning calorimetry. A possible mechanism for the transient phase is proposed. It allows to simulate the growth and the consumption of the θ-Ni2Si during the growth of the δ-Ni2Si silicide.
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68.55.at Other materials
68.55.-a Thin film structure and morphology
82.20.-w Chemical kinetics and dynamics
81.15.Cd Deposition by sputtering

Carrier relaxation dynamics of ZnxCd1−xSe/C core/shell nanocrystals with phase separation as studied by time-resolved cathodoluminescence

Y. Estrin, D. H. Rich, O. Moshe, Sayan Bhattacharyya, and A. Gedanken

Appl. Phys. Lett. 95, 181903 (2009); http://dx.doi.org/10.1063/1.3257975 (3 pages)

Online Publication Date: 2 November 2009

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The optical properties and carrier relaxation kinetics of ZnxCd1−xSe/C core/shell nanocrystals with compositional phase separation occurring on a ∼ 1–5 nm size scale were examined with time-resolved cathodoluminescence (CL) spectroscopy and imaging. The CL spectral lineshape was found to depend on the level of excitation, temperature, and the time-window during time-delayed spectroscopy. The kinetics of carrier thermalization and transfer between Cd-rich phase-separated regions and the homogenous ZnCdSe alloy were examined. We show that the rare phenomenon of compositional phase separation in II-VI nanocrystals leads to interesting and potentially useful optical properties.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
64.75.Qr Phase separation and segregation in semiconductors
73.63.Bd Nanocrystalline materials
81.05.Dz II-VI semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence

Enhancement of magnetoelectric effect in multiferroic fibrous nanocomposites via size-dependent material properties

E. Pan, X. Wang, and R. Wang

Appl. Phys. Lett. 95, 181904 (2009); http://dx.doi.org/10.1063/1.3257980 (3 pages) | Cited 6 times

Online Publication Date: 2 November 2009

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We investigate the effective material properties of a multiferroic fibrous nanocomposite with size effects along its interface. The closed-form expression of the effective moduli of the nanocomposite shows that its response with interface effects depends on the size of the embedded fibers in the composite, a phenomenon different from the result based on the classical theory. We further demonstrate that the magnetoelectric effect can be substantially enhanced via proper design of the interface, providing an alternative avenue for controlling and, in particularly, increasing the magnetoelectric effect.
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75.80.+q Magnetomechanical effects, magnetostriction
68.35.Md Surface thermodynamics, surface energies
77.84.Lf Composite materials
77.65.-j Piezoelectricity and electromechanical effects

Anomaly of critical stress in stress-induced transformation of NiCoMnIn metamagnetic shape memory alloy

Xiao Xu, Wataru Ito, Rie Y. Umetsu, Ryosuke Kainuma, and Kiyohito Ishida

Appl. Phys. Lett. 95, 181905 (2009); http://dx.doi.org/10.1063/1.3254250 (3 pages) | Cited 8 times

Online Publication Date: 2 November 2009

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Stress-induced martensitic transformation below room temperature for a Ni45Co5Mn36.1In13.9 single-crystal, in which no martensitic transformation occurs during cooling down to 4.2 K under zero stress, was investigated by using compression test. The equilibrium stress estimated from the critical stresses in stress-induced forward and reverse transformations decreased with decreasing temperature, while it became almost constant at temperatures below about 140 K. This anomaly can be explained by the abnormal temperature dependence of the transformation entropy change, which has also been detected by magnetization measurement.
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81.40.Lm Deformation, plasticity, and creep
62.20.fg Shape-memory effect; yield stress; superelasticity
64.70.kd Metals and alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
81.70.-q Methods of materials testing and analysis
81.40.Jj Elasticity and anelasticity, stress-strain relations
65.40.gd Entropy
81.30.Kf Martensitic transformations

Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN

B. Alling, M. Odén, L. Hultman, and I. A. Abrikosov

Appl. Phys. Lett. 95, 181906 (2009); http://dx.doi.org/10.1063/1.3256196 (3 pages) | Cited 9 times

Online Publication Date: 2 November 2009

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The influence of pressure on the phase stabilities of Ti1−xAlxN solid solutions has been studied using first principles calculations. We find that the application of hydrostatic pressure enhances the tendency for isostructural decomposition, including spinodal decomposition. The effect originates in the gradual pressure stabilization of cubic AlN with respect to the wurtzite structure and an increased isostructural cubic mixing enthalpy with increased pressure. The influence is sufficiently strong in the composition-temperature interval corresponding to a shoulder of the spinodal line that it could impact the stability of the material at pressures achievable in the tool-work piece contact during cutting operations.
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62.50.-p High-pressure effects in solids and liquids
64.75.Nx Phase separation and segregation in solid solutions
64.75.Ef Mixing
65.40.G- Other thermodynamical quantities
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