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9 Jul 2012

Volume 101, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 101, 023101 (2012); http://dx.doi.org/10.1063/1.4731792 (4 pages)

Feng Wang, Ayan Chakrabarty, Fred Minkowski, Kai Sun, and Qi-Huo Wei
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Long minority carrier lifetime in Au-catalyzed GaAs/AlxGa1−xAs core-shell nanowires

N. Jiang, P. Parkinson, Q. Gao, S. Breuer, H. H. Tan, J. Wong-Leung, and C. Jagadish

Appl. Phys. Lett. 101, 023111 (2012); http://dx.doi.org/10.1063/1.4735002 (4 pages) | Cited 3 times

Online Publication Date: 11 July 2012

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GaAs/AlxGa1−xAs core-shell nanowires were grown by metal organic chemical vapor deposition with optimized AlxGa1−xAs shell and twin-free Au-catalyzed GaAs cores. Time-resolved photoluminescence measurements were carried out on single nanowires at room temperature, revealing minority carrier lifetimes of 1.02 ± 0.43 ns, comparable to self-assisted nanowires grown by molecular beam epitaxy. The long minority carrier lifetimes are mainly attributed to improvement of the GaAs/AlxGa1−xAs interface quality. The upper limit of surface recombination velocity of the structure is calculated to be 1300 cm/s with the AlxGa1−xAs shell grown at 750 °C, which is comparable with planar double heterostructures.
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73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ey III-V semiconductors
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Surface enhanced Raman scattering and localized surface plasmon resonance of nanoscale ultrathin films prepared by atomic layer deposition

Ming Chih Lin, Li-Wei Nien, Ching-Hsiang Chen, Chia-Wei Lee, and Miin-Jang Chen

Appl. Phys. Lett. 101, 023112 (2012); http://dx.doi.org/10.1063/1.4729411 (5 pages) | Cited 1 time

Online Publication Date: 11 July 2012

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An approach was proposed to characterize nanoscale ultrathin films using surface enhanced Raman scattering (SERS). Raman spectroscopy of the TiO2 film as thin as ∼2 nm, which was prepared by atomic layer deposition, was obtained by depositing a nanostructured Au layer on the film surface. Red-shift in the extinction spectrum of the nanostructured Au layer was observed with increasing TiO2 film thickness, ascribed to the increase in effective refractive index of the substrate slab and coupled plasmon resonance. This SERS technique can be applied to investigate a variety of solid-state ultrathin films in nanosclae materials and devices in future studies.
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78.30.Hv Other nonmetallic inorganics
81.07.Bc Nanocrystalline materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.16.-c Methods of micro- and nanofabrication and processing
68.55.A- Nucleation and growth
73.22.Lp Collective excitations

Acoustic and breathing phonon modes in bilayer graphene with Moiré patterns

Jin-Wu Jiang, Bing-Shen Wang, and Timon Rabczuk

Appl. Phys. Lett. 101, 023113 (2012); http://dx.doi.org/10.1063/1.4735246 (4 pages) | Cited 2 times

Online Publication Date: 12 July 2012

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The lattice dynamics properties are investigated for twisting bilayer graphene. There are big jumps for the inter-layer potential at twisting angle θ = 0° and 60°, implying the stability of Bernal-stacking and the instability of AA-stacking structures, while a long platform in [8,55]° indicates the ease of twisting bilayer graphene in this wide angle range. Significant frequency shifts are observed for the z breathing mode around θ = 0° and 60°, while the frequency is a constant in a wide range [8,55]°. Using the z breathing mode, a mechanical nanoresonator is proposed to operate on a robust resonant frequency in terahertz range.
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63.20.-e Phonons in crystal lattices
61.48.Gh Structure of graphene

Enhanced electrical and dielectric properties of polymer covered silicon nanowire arrays

Kamran Rasool, M. A. Rafiq, C. B. Li, E. Krali, Z. A. K. Durrani, and M. M. Hasan

Appl. Phys. Lett. 101, 023114 (2012); http://dx.doi.org/10.1063/1.4735278 (4 pages) | Cited 5 times

Online Publication Date: 12 July 2012

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We investigate DC and AC electrical characteristics of ∼40 μm long p-type silicon nanowire (SiNW) arrays, prepared by metal assisted chemical etching and filled with polyacrylic acid (PAA). PAA diluted to different concentrations with deionized (DI) water is incorporated into the arrays in three steps, yielding polymer filling to the bottom of the arrays. DC and AC electrical measurements show that PAA reduces the array resistance. The AC conductivity increases up to ∼1000 times, and the real part of the overall dielectric constant (ɛ′) by ∼100. We attribute these effects to the formation of acceptor-like states at nanowire/polymer interface.
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77.22.Ch Permittivity (dielectric function)
81.65.Cf Surface cleaning, etching, patterning
73.63.Bd Nanocrystalline materials

Piezoelectrically actuated time-averaged atomic microtraps

A. D. West, C. G. Wade, K. J. Weatherill, and I. G. Hughes

Appl. Phys. Lett. 101, 023115 (2012); http://dx.doi.org/10.1063/1.4736580 (4 pages) | Cited 3 times

Online Publication Date: 12 July 2012

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We present a scheme for creating tight and adiabatic time-averaged atom-traps through the piezoelectric actuation of nanomagnetic structures. We show that potentials formed by the circular translation of magnetic structures have several advantages over conventional rotating-field techniques, particularly for high trap frequencies. As the magnitude of the actuation is changed, the trapping potential can be changed adiabatically between harmonic 3D confinement and a toroidal trap.
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85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Two-dimensional magnetotransport in Bi2Te2Se nanoplatelets

Pascal Gehring, Bo Gao, Marko Burghard, and Klaus Kern

Appl. Phys. Lett. 101, 023116 (2012); http://dx.doi.org/10.1063/1.4736404 (4 pages) | Cited 5 times

Online Publication Date: 13 July 2012

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Single-crystalline Bi2Te2Se nanoplates with thicknesses between 8 and 30 nm and lateral sizes of several micrometers were synthesized by a vapour-solid growth method. Angle-dependent magnetoconductance measurements on individual nanoplates revealed the presence of a two-dimensional weak anti-localization effect. In conjunction with gate-dependent charge transport studies performed at different temperatures, evidence was gained that this effect originates from the topologically protected surface states of the nanoplates.
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72.20.My Galvanomagnetic and other magnetotransport effects
73.20.Fz Weak or Anderson localization
73.61.Ng Insulators
81.07.Bc Nanocrystalline materials

Aerosol fabrication of thermosensitive nanogels and in situ hybridization with iron nanoparticles

Jeong Hoon Byeon and Jang-Woo Kim

Appl. Phys. Lett. 101, 023117 (2012); http://dx.doi.org/10.1063/1.4736574 (4 pages) | Cited 1 time

Online Publication Date: 13 July 2012

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Collison atomized n-isopropylacrylamide (NIPAM) droplets were thermally treated with different furnace wall temperatures to form nanogels in an aerosol state. The size of the aerosol nanogels decreased from 40.3 nm to 32.8 nm by increasing the temperature from 40 °C to 90 °C due to the coil-to-globule transition of the NIPAM. A serial reactor consisting of a spark generator coupled to a collison atomizer was further employed to efficiently (>90% in production yield) fabricate biocompatible (78.8% in cell viability)-magnetic (30.3 emu g−1 in saturation magnetization) hybrid nanogels of NIPAM and iron nanoparticles.
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81.20.Rg Aerosols in materials synthesis and processing
82.70.Gg Gels and sols
82.70.Rr Aerosols and foams
81.07.Bc Nanocrystalline materials

Lifetime imaging of radiative and non-radiative fluorescence decays on nanoplasmonic surface

Manas Ranjan Gartia, John P. Eichorst, Robert M. Clegg, and G. Logan Liu

Appl. Phys. Lett. 101, 023118 (2012); http://dx.doi.org/10.1063/1.4736575 (5 pages)

Online Publication Date: 13 July 2012

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We report the fluorescence lifetime imaging and quantum yield measurement of five different fluorescence dyes spanning different quantum yield and excitation wavelength ranges in solution as well as on irregular nanoplasmonic substrate surface. Due to a distribution of dye molecules at random distances and orientation to the metal nanoplasmonic structure, the dyes showed multi-component lifetime decays on the surface. We have simulated the distribution of lifetime on the surface based on fractional intensity relative to steady-state value and derived an average lifetime with species fraction. From the quantum yield and fluorescence lifetime measurements we calculated the modified radiative and non-radiative decay rates for the dyes due to energy coupling on the substrate. We measured up to 100 fold fluorescence enhancement on nanoplasmonic substrate, and all molecule fluorescence showed not only considerably higher radiative decay rate but also higher non-radiative decay rate.
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73.22.Lp Collective excitations
78.55.Kz Solid organic materials
71.35.-y Excitons and related phenomena

Ultrafast room temperature wiping-rubbing fabrication of graphene nanosheets as flexible transparent conductive films with high surface stability

Yan Yu, Shenglin Jiang, Wenli Zhou, Xiangshui Miao, Yike Zeng, Guangzu Zhang, Yangyang Zhang, Qingfeng Zhang, and Han Zhao

Appl. Phys. Lett. 101, 023119 (2012); http://dx.doi.org/10.1063/1.4736576 (5 pages) | Cited 3 times

Online Publication Date: 13 July 2012

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In this letter, we developed an original innovative wiping-rubbing method to fabricate flexible transparent conductive films (TCFs) based on graphene nanosheets. We achieved this by using only commercial graphite block and polycarbonate film as raw materials, through a cost effective and ultrafast room temperature wiping-rubbing process (within 2 min). The properties of our flexible TCFs were competitive when comparing with literature reported graphene TCFs. Our flexible TCFs showed enough surface stability under a series of surface destructive treatments. The physical mechanism aspects of wiping-rubbing processes and surface stability were discussed.
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81.05.ue Graphene
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.16.-c Methods of micro- and nanofabrication and processing

Magnetovoltaic effect in a quantum dot undergoing Jahn-Teller transition

Shyamalendu M. Bose, Didier Ndengeyintwali, Surjyo N. Behera, and Peter Entel

Appl. Phys. Lett. 101, 023120 (2012); http://dx.doi.org/10.1063/1.4737009 (4 pages)

Online Publication Date: 13 July 2012

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A model is proposed to study the electrical transport properties of a quantum dot capable of undergoing a structural phase transition driven by the Jahn-Teller mechanism. The dot attached to two metallic leads is described by the single impurity Anderson model Hamiltonian to which a term describing the Jahn-Teller distortion and another term to include the possibility of the presence of a magnetic field are added. Calculation of the electrical conductance and Jahn-Teller order parameter reveals several interesting features the most striking of which is the new phenomenon of “magnetovoltaic effect.”
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73.63.Kv Quantum dots
75.85.+t Magnetoelectric effects, multiferroics
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
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Improving an organic photodiode by incorporating a tunnel barrier between the donor and acceptor layers

I. H. Campbell and B. K. Crone

Appl. Phys. Lett. 101, 023301 (2012); http://dx.doi.org/10.1063/1.4734505 (3 pages) | Cited 2 times

Online Publication Date: 9 July 2012

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We demonstrate increased photocurrent quantum efficiency in a model donor/acceptor (tetracene/C60) photodiode by incorporating an insulating tunnel barrier between the tetracene and C60 layers. Photodiode efficiency results from the interplay of a number of processes which add to or subtract from the overall device efficiency. The positive rates are those of exciton dissociation and charge separation, the negative rates include exciton and charge transfer complex recombination. We show that by introducing a thin insulating layer between the donor and acceptor layers in a photodiode, we can modify the exciton dissociation and charge transfer complex recombination rates and improve device performance.
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85.60.Dw Photodiodes; phototransistors; photoresistors
FREE

Tetrathiofulvalene and tetracyanoquinodimethane crystals: Conducting surface versus interface

T. Mathis, K. Mattenberger, P. Moll, and B. Batlogg

Appl. Phys. Lett. 101, 023302 (2012); http://dx.doi.org/10.1063/1.4731244 (3 pages)

Online Publication Date: 10 July 2012

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When a tetrathiofulvalene (TTF) crystal is placed onto a 7,7,8,8‐tetracyanoquinodimethane (TCNQ) crystal at room temperature, a highly conducting layer is formed. In this study, we explore to what degree this is due to physical contact or transfer by sublimation of one species onto the other crystal. We have performed a variety of time‐dependent surface conductivity measurements, including TTF lamination on TCNQ at room temperature and low temperatures, as well as deposition of TTF molecules from the gas phase. Crystal-to-crystal contact insignificantly modifies material conductivity while TTF sublimation onto TCNQ is shown to dominate electronic modification.
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73.25.+i Surface conductivity and carrier phenomena
68.35.Ct Interface structure and roughness
64.70.Hz Solid-vapor transitions
72.80.Le Polymers; organic compounds (including organic semiconductors)
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Sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor

Hsiao-Wen Zan, Chang-Hung Li, Chih-Kuan Yu, and Hsin-Fei Meng

Appl. Phys. Lett. 101, 023303 (2012); http://dx.doi.org/10.1063/1.4734498 (4 pages) | Cited 1 time

Online Publication Date: 11 July 2012

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We report a very sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor. The oxidizing and reducing gases act as electron dedoping and electron doping agents on the transistor active layer to change the potential distribution in the vertical channel and hence to change the output current density. With a 30-ppb detection limit to ammonia, the sensor can be used for non-invasive breath monitor in point-of-care applications. The integration of a sensitive gas sensor and a low-operation-voltage transistor in one single device also facilitates the development of low-cost and low-power-consumption sensor array.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.30.Fg Bulk semiconductor and conductivity oscillation devices (including Hall effect devices, space-charge-limited devices, and Gunn effect devices)
85.30.Tv Field effect devices
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Highly efficient inverted top-emitting green phosphorescent organic light-emitting diodes on glass and flexible substrates

E. Najafabadi, K. A. Knauer, W. Haske, C. Fuentes-Hernandez, and B. Kippelen

Appl. Phys. Lett. 101, 023304 (2012); http://dx.doi.org/10.1063/1.4736573 (4 pages) | Cited 4 times

Online Publication Date: 11 July 2012

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Green phosphorescent inverted top-emitting organic light-emitting diodes with high current efficacy and luminance are demonstrated on glass and polyethersulfone (PES) substrates coated with polyethylene dioxythiophene-polystyrene sulfonate (PEDOT:PSS). The bottom cathode is an aluminum/lithium fluoride bilayer that injects electrons efficiently into an electron transport layer of 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TpPyPB). The cathode is found to be highly sensitive to the exposure of trace amounts of O2 and H2O. A high current efficacy of 96.3 cd/A is achieved at a luminance of 1387 cd/m2 when an optical outcoupling layer of N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine (α-NPD) is deposited on the anode.
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85.60.Jb Light-emitting devices
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Intermolecular hydrogen-bonded organic semiconductors—Quinacridone versus pentacene

Eric Daniel Głowacki, Lucia Leonat, Mihai Irimia-Vladu, Reinhard Schwödiauer, Mujeeb Ullah, Helmut Sitter, Siegfried Bauer, and Niyazi Serdar Sariciftci

Appl. Phys. Lett. 101, 023305 (2012); http://dx.doi.org/10.1063/1.4736579 (4 pages) | Cited 1 time

Online Publication Date: 12 July 2012

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Quinacridone is a five-ring hydrogen-bonded molecule analogous in structure and size to the well-known organic semiconductor pentacene. Unlike pentacene, quinacridone has limited intramolecular π-conjugation and becomes highly colored in the solid state due to strong intermolecular electronic coupling. We found that quinacridone shows a field-effect mobility of 0.1 cm2/V·s, comparable to mobilities of pentacene in similarly prepared devices. Photoinduced charge generation in single-layer quinacridone metal-insulator-metal diodes is more than a hundred times more efficient than in pentacene devices. Photoinduced charge transfer from quinacridone to C60 is not effective, as evidenced by measurements in heterojunctions with C60. Hydrogen-bonded organic solids may provide new avenues for organic semiconductor design.
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85.30.Tv Field effect devices
FREE

Efficient organic light-emitting diodes through up-conversion from triplet to singlet excited states of exciplexes

Kenichi Goushi and Chihaya Adachi

Appl. Phys. Lett. 101, 023306 (2012); http://dx.doi.org/10.1063/1.4737006 (4 pages) | Cited 4 times

Online Publication Date: 12 July 2012

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Enhanced electroluminescence efficiency is achieved in organic light-emitting diodes through delayed fluorescence of the exciplex state formed between 4,4′,4′′-tris[3-methylphenyl(phenyl)amino]-triphenylamine (m-MTDATA) as an electron-donating material and 2,8-bis(diphenylphosphoryl)dibenzo-[b,d]thiophene (PPT) as an electron-accepting material. The devices exhibited maximum external electroluminescence quantum and power efficiencies of 10.0% and 47.0 lm/W, respectively.
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85.60.Jb Light-emitting devices
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Electrostatic capacitance in single and double layer organic diodes

Feilong Liu, P. Paul Ruden, Ian. H. Campbell, and Darryl L. Smith

Appl. Phys. Lett. 101, 023501 (2012); http://dx.doi.org/10.1063/1.4734379 (4 pages)

Online Publication Date: 9 July 2012

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The electrostatic capacitance-voltage characteristics of single and double layer organic diodes are explored by numerical simulation and theoretical analysis. For single layer devices, the capacitance in the high voltage limit is approximately 3/2 times the geometric capacitance C0 for unipolar carrier injection or ambipolar injection with high recombination rates, and 4/πC0 for symmetric ambipolar injection with low recombination rates. For double layer devices, the capacitance is determined by the relative charge distribution at the contacts, in the bulk region of the two layers, and at their interface. The charge distribution is affected by the injection barrier height and by exciplex-controlled interface recombination.
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85.30.Kk Junction diodes
02.60.-x Numerical approximation and analysis
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems

Directional anemometer based on an anisotropic flat-clad tapered fiber Michelson interferometer

Cheng-Ling Lee, Chung-Fen Lee, Chai-Ming Li, Tsai-Ching Chiang, and Ying-Li Hsiao

Appl. Phys. Lett. 101, 023502 (2012); http://dx.doi.org/10.1063/1.4734501 (4 pages)

Online Publication Date: 10 July 2012

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This work demonstrates a sensitive directional anemometer that is based on a pendulum-type of anisotropic flat-clad tapered fiber Michelson interferometer (AFCTFMI). The AFCTFMI is fabricated by tapering an anisotropic flat-cladding fiber to establish structural anisotropy, and enables the sensing of the direction and magnitude of flowing air (wind). Wavelength shifts and fringes visibility of the measured interference fringes are correlated with the magnitude and furthermore the direction of the wind. Experimental results agree closely with the theoretical analysis. The directional anemometer can simultaneously and effectively indicate the direction, and sensitively measure the magnitude of wind.
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93.85.-q Instruments and techniques for geophysical research: Exploration geophysics
06.30.Gv Velocity, acceleration, and rotation

Pulse energy measurement at the hard x-ray laser in Japan

M. Kato, T. Tanaka, T. Kurosawa, N. Saito, M. Richter, A. A. Sorokin, K. Tiedtke, T. Kudo, K. Tono, M. Yabashi, and T. Ishikawa

Appl. Phys. Lett. 101, 023503 (2012); http://dx.doi.org/10.1063/1.4733354 (4 pages) | Cited 2 times

Online Publication Date: 10 July 2012

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The pulse energies of a free electron laser have accurately been measured in the hard x-ray spectral range. In the photon energy regime from 4.4 keV to 16.8 keV, pulse energies up to 100 μJ were obtained at the hard x-ray laser facility SACLA (SPring-8 Ångstrom Compact free-electron LAser). Two independent methods, using a cryogenic radiometer and a gas monitor detector, were applied and agreement within 3.3% was achieved. Based on our validated pulse energy measurement, a SACLA online monitor detector could be calibrated for all future experiments.
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42.55.Vc X- and γ-ray lasers
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
06.20.fb Standards and calibration
41.60.Cr Free-electron lasers

Increased dissipation from distributed etch holes in a lateral breathing mode silicon micromechanical resonator

Cheng Tu and Joshua E.-Y. Lee

Appl. Phys. Lett. 101, 023504 (2012); http://dx.doi.org/10.1063/1.4733728 (4 pages) | Cited 1 time

Online Publication Date: 10 July 2012

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Etch holes are commonly used design features when fabricating silicon-on-insulator micromechanical resonators to realize free standing structures. This paper shows that including etch-holes in a square-extensional mode resonator results in marked reduction of quality factor (Q) by 75%. The cause of this drop is explained by our finite element model used to theoretically estimate Q. These theoretical estimates agree well with measurement results. Our analyses show that anchor loss is dominant in a plain structure while etch holes increase thermoelastic damping to the point where both dissipation factors become comparable in determining the actual Q.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
07.10.Cm Micromechanical devices and systems

Reading and writing charge on graphene devices

M. R. Connolly, E. D. Herbschleb, R. K. Puddy, M. Roy, D. Anderson, G. A. C. Jones, P. Maksym, and C. G. Smith

Appl. Phys. Lett. 101, 023505 (2012); http://dx.doi.org/10.1063/1.4732802 (4 pages) | Cited 1 time

Online Publication Date: 11 July 2012

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We use a combination of charge writing and scanning gate microscopy to map and modify the local charge neutrality point of graphene field-effect devices. We give a demonstration of the technique by writing remote charge in a thin dielectric layer over a graphene-metal interface and detecting a shift in the local charge neutrality point. We perform electrostatic simulations to characterize the interaction between a realistic scanning probe tip, the deposited charge, and the graphene and find a good semi-quantitative agreement with the experimental results.
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85.65.+h Molecular electronic devices

Kilohertz magnetic field focusing and force enhancement using a metallic loop array

Ercan M. Dede, Jaewook Lee, Yuanbo Guo, Li Qin Zhou, Minjuan Zhang, and Debasish Banerjee

Appl. Phys. Lett. 101, 023506 (2012); http://dx.doi.org/10.1063/1.4737003 (4 pages)

Online Publication Date: 12 July 2012

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We present a device capable of focusing a kilohertz magnetic field and enhancing the associated magnetic force. The device comprises a two-by-two array of electrically conductive metallic loops embedded in a base substrate. Analytical calculations and numerical simulations verify that the induced electrical current in the loop structure influences the magnetic field distribution thus leading to magnetic force enhancement. Experimental measurements of the magnetic force generated by the device operating at one kilohertz are compared with measurements of a control sample without loops. Such devices have logical applications in electromechanical actuators and transducers.
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41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles
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Stability of electrically induced-polarization in poly (L-lactic) acid for bone regeneration

Nathalie Barroca, Paula M. Vilarinho, Maria Helena V. Fernandes, Pankaj Sharma, and Alexei Gruverman

Appl. Phys. Lett. 101, 023701 (2012); http://dx.doi.org/10.1063/1.4729619 (4 pages) | Cited 1 time

Online Publication Date: 10 July 2012

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This paper describes the decay kinetics of electrically induced polarization of poly(L-lactic) acid (PLLA) via piezoresponse force microscopy. Two crystalline forms of PLLA (α and α′) were electrically poled at different temperatures (room and above glass transition). Poling at temperatures above glass transition allowed obtaining polarization stable up to 10 days for both forms. This period is enough to trigger and maintain proteins adhesion and cells proliferation, if PLLA is used as a platform for tissue growth. When poled at room temperature, both structures lose polarization after a short time (minutes to hours) being polarization in α PLLA stable for longer time.
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87.85.jj Biocompatibility
87.17.-d Cell processes
87.14.E- Proteins

Lipid bilayer array for simultaneous recording of ion channel activities

Ayumi Hirano-Iwata, Tomohiro Nasu, Azusa Oshima, Yasuo Kimura, and Michio Niwano

Appl. Phys. Lett. 101, 023702 (2012); http://dx.doi.org/10.1063/1.4736263 (3 pages) | Cited 2 times

Online Publication Date: 12 July 2012

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This paper describes an array of stable and reduced-solvent bilayer lipid membranes (BLMs) formed in microfabricated silicon chips. BLMs were first vertically formed simultaneously and then turned 90° in order to realize a horizontal BLM array. Since the present BLMs are mechanically stable and robust, the BLMs survive this relatively tough process. Typically, a ∼60% yield in simultaneous BLM formation over 9 sites was obtained. Parallel recordings of gramicidin channel activities from different BLMs were demonstrated. The present system has great potential as a platform of BLM-based high throughput drug screening for ion channel proteins.
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87.16.dp Transport, including channels, pores, and lateral diffusion
87.16.Vy Ion channels
85.30.-z Semiconductor devices

Nanostructured nickel oxide film for application to fish freshness biosensor

Surendra K. Yadav, Jay Singh, Ved Varun Agrawal, and B. D. Malhotra

Appl. Phys. Lett. 101, 023703 (2012); http://dx.doi.org/10.1063/1.4736578 (4 pages) | Cited 1 time

Online Publication Date: 13 July 2012

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Xanthine oxidase (XOx) has been physisorbed onto nanostructured nickel oxide (n-NiO, ∼41 nm), electrophoretically deposited onto indium-tin-oxide (ITO) glass substrate using poly-ethylene glycol via co-precipitation. The electrochemical response studies of the XOx/n-NiO/ITO bioelectrode show linear response in the xanthine concentration range as 10–200 μM (R2 = 0.9989), sensitivity as 0.6214 μA/μM cm2, detection limit as 2.989 μM, standard deviation as 0.6192 μA, response time of 15 s with the stability of 100 days. The observed low value (0.0306 mM) Michaelis–Menten constant (Km) indicates high affinity of XOx towards xanthine.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.10.Cm Micromechanical devices and systems
81.15.Pq Electrodeposition, electroplating
81.16.Be Chemical synthesis methods
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
87.14.ej Enzymes
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