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12 Sep 2005

Volume 87, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 87, 113902 (2005); http://dx.doi.org/10.1063/1.2045549 (3 pages)

M. Laroussi and X. Lu
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Single-crystalline nanotubes of IIB-VI semiconductors

J. Q. Hu, Y. Bando, J. H. Zhan, M. Y. Liao, D. Golberg, X. L. Yuan, and T. Sekiguchi

Appl. Phys. Lett. 87, 113107 (2005); http://dx.doi.org/10.1063/1.2042634 (3 pages) | Cited 17 times

Online Publication Date: 7 September 2005

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Wurtzite-type CdS and CdSe nanotubes have been grown via a Sn nanowire-templated route under thermal annealing. The tubes are structurally uniform and defect-free single crystals, and partially or completely filled with Sn nanowires; most of the tubes display pin-like structures showing significant tapering along their axes. Cathodoluminescence spectra reveal that CdS and CdSe nanotubes have profound emission peaks at ∼ 512 and ∼ 724 nm. The luminescence intensities vary between Sn filled and unfilled tube parts. Keeping in mind that ZnS and ZnSe nanotubes may also be synthesized using the similar technique, we propose that the present method is a universal synthetic route toward single-crystalline IIB-VI group semiconductor nanotubes.
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81.07.De Nanotubes
81.05.Dz II-VI semiconductors
81.16.-c Methods of micro- and nanofabrication and processing
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.60.Hk Cathodoluminescence, ionoluminescence
78.67.Ch Nanotubes
61.72.Cc Kinetics of defect formation and annealing

Characterization of SnO2 nanowires as an anode material for Li-ion batteries

Z. Ying, Q. Wan, H. Cao, Z. T. Song, and S. L. Feng

Appl. Phys. Lett. 87, 113108 (2005); http://dx.doi.org/10.1063/1.2045550 (3 pages) | Cited 44 times

Online Publication Date: 8 September 2005

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SnO2 nanowires synthesized by thermal evaporation method are investigated as a possible anode electrode for Li-ion batteries. In the first discharge process, the capacity of Li ions is 2133 mA h g−1, which is much more than the theoretical total capacity of the bulk SnO2, 1494 mA h g−1. During the successive 15 cycles, the reversible capacity stays in the range of 1250–700 mA h g−1 with a capacity fading of 3.89% per cycle at a constant current density of 0.5 mA cm−2. These results demonstrate that SnO2 nanowires are a promising anode material for Li-ion battery applications.
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82.45.Fk Electrodes
82.47.Aa Lithium-ion batteries
68.65.La Quantum wires (patterned in quantum wells)
81.07.Vb Quantum wires
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Growth of inclined boron nanowire bundle arrays in an oxide-assisted vapor-liquid-solid process

S. H. Yun, J. Z. Wu, A. Dibos, X. Gao, and U. O. Karlsson

Appl. Phys. Lett. 87, 113109 (2005); http://dx.doi.org/10.1063/1.2046728 (3 pages) | Cited 12 times

Online Publication Date: 8 September 2005

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In the vapor-liquid-solid process typically employed for semiconductor nanowire growth, nucleation and anisotropic crystal growth of single nanowires are achieved with generation of a solid/liquid alloy interface using metal catalysts. The nucleation and growth mechanism of nanowires may be greatly altered when a second liquid is introduced into the solid/liquid alloy interface. In this work, we demonstrate bundled boron nanowire (BNW) array growth on Au coated Si substrates by introducing a second liquid of B2O3 onto the solid (B)/liquid alloy (Au-B) interface. The BNWs in each bundle are straight but highly inclined with respect to the normal of the substrate. A study of BNW morphology and chemical elemental distribution using electron microscopy and energy dispersive x-ray spectroscopy suggested that the catalyst Au provided the nucleation site for BNW bundles while the liquid B2O3 modified the initiation of BNWs from each nucleation site, resulting in multiple initiation of the BNWs from each site.
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81.07.Bc Nanocrystalline materials
81.05.Cy Elemental semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.16.-c Methods of micro- and nanofabrication and processing
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Tungsten nanocrystals embedded in high-k materials for memory application

S. K. Samanta, Won Jong Yoo, Ganesh Samudra, Eng Soon Tok, L. K. Bera, and N. Balasubramanian

Appl. Phys. Lett. 87, 113110 (2005); http://dx.doi.org/10.1063/1.2045555 (3 pages) | Cited 33 times

Online Publication Date: 9 September 2005

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The formation of tungsten nanocrystals (W-NCs) on atomic-layer-deposited HfAlO/Al2O3 tunnel oxide was demonstrated for application in a memory device. It was found that the density and size distribution of W-NCs are not only controlled by the initial film thickness, annealing temperature, and time, but also by the metal∕tunnel oxide interface structure. Well-isolated W-NCs with an average diameter of 5 nm and a surface density of 5×1011 cm−2 were obtained by applying a thin Al2O3 wetting layer onto HfAlO tunneling oxide. A large flatband voltage shift of 5.7 V was observed from capacitance–voltage measurement when a bias voltage up to ±4 V was applied.
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81.07.Bc Nanocrystalline materials
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.35.Ct Interface structure and roughness
73.40.Ns Metal-nonmetal contacts
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.40.Gh Other heat and thermomechanical treatments
61.46.-w Structure of nanoscale materials

Electron-beam-induced growth of silicon multibranched nanostructures

Luis F. Fonseca, Oscar Resto, and Francisco Solá

Appl. Phys. Lett. 87, 113111 (2005); http://dx.doi.org/10.1063/1.2045564 (3 pages) | Cited 4 times

Online Publication Date: 9 September 2005

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Although successful nanobranching has been demonstrated for some materials using a variety of methods, the controlled fabrication of multibranched nanostructures of silicon is an important challenge faced by nanotechnologist; because it is crucial for the assembly of electronic interconnects at the atomic scale. Here, we report an electron-beam-induced approach that enables to grow silicon nanobranched structures at specific locations and to control the growth process at the nanoscale level. We further present a detailed in situ imaging of the growth dynamics and explain the results by a qualitative model based on local heating and charge concentration processes.
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81.07.Bc Nanocrystalline materials
81.05.Cy Elemental semiconductors
61.82.Rx Nanocrystalline materials
61.46.-w Structure of nanoscale materials
73.63.Bd Nanocrystalline materials

Room-temperature operation of a nanoelectromechanical resonator embedded in a phase-locked loop

T. Kouh, O. Basarir, and K. L. Ekinci

Appl. Phys. Lett. 87, 113112 (2005); http://dx.doi.org/10.1063/1.2048813 (3 pages) | Cited 5 times

Online Publication Date: 9 September 2005

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We describe the operation of a phase-locked loop (PLL) that tracks the high-frequency electromechanical resonance of a nanoscale beam resonator. The fundamental in-plane flexural resonance of the beam resonator embedded in the PLL is actuated electrostatically and detected optically. PLL operation is demonstrated by locking stably to the resonance frequency of the beam, and by tracking this resonance with high fidelity as the beam is mass loaded. Our analysis reproduces the observed locking behavior. Feedback control schemes for nanoelectromechanical resonators may offer prospects for miniature timekeeping devices and ultrasensitive sensors.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.10.Cm Micromechanical devices and systems

TiO2 single-crystalline nanorod electrode for quasi-solid-state dye-sensitized solar cells

Mi Yeon Song, Young Rack Ahn, Seong Mu Jo, Dong Young Kim, and Jae-Pyoung Ahn

Appl. Phys. Lett. 87, 113113 (2005); http://dx.doi.org/10.1063/1.2048816 (3 pages) | Cited 66 times

Online Publication Date: 9 September 2005

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TiO2 single-crystalline nanorods are prepared from electrospun fibers which are composed of nanofibrils with an islands-in-a-sea morphology. The mechanical pressure produces each fibril into nanorods which are converted to anatase single crystals after calcination. High-resolution transmission electron microscopy shows that the (001) plane is growing along the longitudinal direction of the rod. In this work, the nanorod electrode provides the efficient photocurrent generation in a quasi-solid-state dye-sensitized solar cell using highly viscous poly(vinylidenefluoride-co-hexafluoropropylene)-based gel electrolytes. The overall conversion efficiency of the TiO2 nanorods shows 6.2% under 100 mW/cm2 (AM 1.5 G) illumination.
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81.07.Bc Nanocrystalline materials
84.60.Jt Photoelectric conversion
81.16.-c Methods of micro- and nanofabrication and processing
72.40.+w Photoconduction and photovoltaic effects
81.40.Gh Other heat and thermomechanical treatments

Patterning of ferroelectric nanodot arrays using a silicon nitride shadow mask

Hyung-Joon Shin, Je Hyuk Choi, Hee Jun Yang, Young Dae Park, Young Kuk, and Chi-Jung Kang

Appl. Phys. Lett. 87, 113114 (2005); http://dx.doi.org/10.1063/1.2048818 (3 pages) | Cited 17 times

Online Publication Date: 9 September 2005

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We grew well-ordered arrays of ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) nanodots on a SrRuO3/SrTiO3 substrate by pulsed laser deposition. A silicon nitride shadow mask with ordered holes was used for patterning of the PZT arrays. Each dot has a height of ∼ 15 nm and a diameter of ∼ 120 nm with a similar dome shape over a large area. The ferroelectric properties of individual PZT dots were investigated by piezoresponse force microscopy. A single dot could be polarized individually and the polarized state remained unrelaxed to ∼ 20 min.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.07.Bc Nanocrystalline materials
81.16.Rf Micro- and nanoscale pattern formation
81.16.Nd Micro- and nanolithography
61.46.-w Structure of nanoscale materials
77.22.Ej Polarization and depolarization

White-light emission of polyvinyl alcohol∕ZnO hybrid nanofibers prepared by electrospinning

X. M. Sui, C. L. Shao, and Y. C. Liu

Appl. Phys. Lett. 87, 113115 (2005); http://dx.doi.org/10.1063/1.2048808 (3 pages) | Cited 55 times

Online Publication Date: 9 September 2005

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Polyvinyl alcohol∕ZnO (PVA∕ZnO) hybrid nanofibers were prepared by the electrospinning technique. The structural and spectral information of the nanofibers was characterized by scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, resonant Raman, and photoluminescence (PL). The results indicate that ZnO were successfully embedded in the one-dimensional hybrid fibers via chemical interactions between ZnO and PVA. PL results show the PVA∕ZnO nanofibers have an intense white-light emission, which originates from the simultaneous emission of three bands covering from the UV to visible range. A possible PL mechanism was proposed accordingly.
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78.55.-m Photoluminescence, properties and materials
61.46.-w Structure of nanoscale materials
78.30.-j Infrared and Raman spectra
81.07.Bc Nanocrystalline materials
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Electrode specific electropolymerization of ethylenedioxythiophene: Injection enhancement in organic transistors

Raoul Schroeder, Leszek A. Majewski, Martin Grell, Jonathan Maunoury, Julien Gautrot, Philip Hodge, and Mike Turner

Appl. Phys. Lett. 87, 113501 (2005); http://dx.doi.org/10.1063/1.2035879 (3 pages) | Cited 16 times

Online Publication Date: 6 September 2005

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In this letter, we report on a method of decreasing the injection barrier from metal electrodes to organic semiconductors, namely pentacene and poly(triarylamine) (PTAA). This method involves the electrodeposition of PEDOT∕PSS on to the source electrode of an organic field-effect transistor (OFET) without unintended doping of the channel. In an OFET, the drain current injected at the PEDOT∕PSS coated gold electrode increases (2–6) fold over that of the current injected at the unmodified gold electrode, all else being the same. Furthermore, in the transistor with a polytriarylamine as the semiconductor, a decrease of the threshold voltage is observed.
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85.30.Tv Field effect devices
81.15.Pq Electrodeposition, electroplating

Display device with dual emissive and reflective modes

X. J. Wang, W. M. Lau, and K. Y. Wong

Appl. Phys. Lett. 87, 113502 (2005); http://dx.doi.org/10.1063/1.2043249 (3 pages) | Cited 14 times

Online Publication Date: 7 September 2005

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A display device with dual electroluminescence and electrochromic display functions is described. The device consists of two layers of polymeric thin films, one of which is an electrochromic polymer and the other an electroluminescence polymer, that are sandwiched between two electrodes. Both polymers are blended with a solid electrolyte. The device functions as an electroluminescence device when positively biased, and as an electrochromic device if biased negatively instead. The measured current density for the electrochromic mode of operation was found to be two orders of magnitude lower than that for the electroluminescence mode. This functional duality demonstrates the successful combination of the option of light-emitting display and the power saving electrochromic mode for portable devices.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
42.79.Kr Display devices, liquid-crystal devices

The effect of interfacial layer on the performance of organic light-emitting diodes

Stelios A. Choulis, Vi-En Choong, Mathew K. Mathai, and Franky So

Appl. Phys. Lett. 87, 113503 (2005); http://dx.doi.org/10.1063/1.2042635 (3 pages) | Cited 73 times

Online Publication Date: 7 September 2005

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We demonstrate high efficiency organic light-emitting devices by incorporation of a nanoscale interfacial layer between a hole-conducting layer (PEDOT:PSS) and a light-emitting polymer layer (LEP) to improve hole injection. The interfacial layer has appropriate highest occupied molecular orbital level in order to act as a bridge for efficient hole injection from the PEDOT:PSS into the LEP. As an example we have incorporated a suitable interfacial layer into a green-emitting single-layer electrophosphorescent light-emitting diode. Devices with the interfacial layer show a peak efficiency of 41 lm/W, an improvement of more than 25% in their performance over comparable devices without the interfacial layer. The results presented here introduce a novel method to improve hole injection and thus efficiency in organic electroluminescent devices.
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85.60.Jb Light-emitting devices

Isobar suppression by photodetachment in a gas-filled rf quadrupole ion guide

Y. Liu, J. R. Beene, C. C. Havener, and J. F. Liang

Appl. Phys. Lett. 87, 113504 (2005); http://dx.doi.org/10.1063/1.2046732 (3 pages) | Cited 6 times

Online Publication Date: 8 September 2005

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A technique based on selective nonresonant laser photodetachment of unwanted negative ion species has been developed for efficient suppression of isobaric contaminants in negative ion beams. A radio-frequency quadrupole ion guide is employed to cool the negative ion beam and dramatically increase the interaction time of the ions with the laser, substantially increasing the efficiency of the photodetachment process. In a proof-of-principle experiment, we achieved 95% suppression of math ions by photodetachment while under identical conditions 10% of math ions were neutralized.
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32.80.Gc Photodetachment of atomic negative ions
07.75.+h Mass spectrometers
42.62.-b Laser applications
07.77.-n Atomic, molecular, and charged-particle sources and detectors

Complementary inverter based on interface doped pentacene

Marcus Ahles, Roland Schmechel, and Heinz von Seggern

Appl. Phys. Lett. 87, 113505 (2005); http://dx.doi.org/10.1063/1.2045556 (3 pages) | Cited 35 times

Online Publication Date: 9 September 2005

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An organic complementary metal–oxide–semiconductor (O-CMOS) inverter is presented, which is based on a single pentacene layer acting both as n- and p-type organic semiconductors. The circuit consists of two spatially separated transistors realized by pairs of calcium and gold source and drain electrodes, respectively. The p transistor is obtained by utilizing the conventional pentacene/SiO2 channel interface whereas the n transistor is realized by doping the SiO2 interface with traces of calcium prior to pentacene deposition. Both, n and p transistors work exclusively in unipolar mode within the range of the supply voltage of 60 V. The O-CMOS inverter works reliably with a gain in between 17 and 24, and the respective electron and hole mobilities were found around 0.1 cm2 V−1 s−1. The circuit shows hysteresis, which can be explained by a gate voltage-dependent electron trapping in the n channel. Electron accumulation can also be realized by the application of a polymethylmethacrylate interlayer between SiO2 and pentacene.
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85.30.Tv Field effect devices

Photovoltaic effect in poly-dioctyl-phenylene-ethynylene-C60 cells upon donor and acceptor excitation

A. G. Umnov and O. J. Korovyanko

Appl. Phys. Lett. 87, 113506 (2005); http://dx.doi.org/10.1063/1.2048817 (3 pages) | Cited 7 times

Online Publication Date: 9 September 2005

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We studied photovoltaic effect in poly-dioctyl-phenylene-ethynylene (PPE)-C60 cells using photovoltage and photocurrent spectroscopy. We observe two-step photoexcitation dependence of open circuit voltage Voc. Two values of Voc are due to different Coulomb binding energies for carriers originated from excitons in PPE and C60. Due to built-in potential between PPE and C60 layers, carriers overcome this exciton binding energy and separate at the heterojunction. We describe our results by energy diagram, comparing exciton binding energies in donor and acceptor moieties.
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85.60.Bt Optoelectronic device characterization, design, and modeling
85.65.+h Molecular electronic devices
72.40.+w Photoconduction and photovoltaic effects
71.35.-y Excitons and related phenomena
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Large deep-ultraviolet photocurrent in metal-semiconductor-metal structures fabricated on as-grown boron-doped diamond

Jose Alvarez, Meiyong Liao, and Yasuo Koide

Appl. Phys. Lett. 87, 113507 (2005); http://dx.doi.org/10.1063/1.2048807 (3 pages) | Cited 4 times

Online Publication Date: 9 September 2005

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Metal-semiconductor-metal planar devices have been fabricated on as-grown boron-doped homoepitaxial diamond thin films. They consist of two Schottky barriers connected back to back. The metal employed was a thin titanium (Ti) layer (5 nm) followed by a gold (Au) cap layer (50 nm), respectively. The structure shows a high ultraviolet photocurrent at 220 nm, which is seven orders of magnitude higher than the reverse dark current (<1 pA) for at least an applied voltage of ±0.4 V. In addition, anomalous photoconductivity gain is observed. A plausible explanation could be the modification of the Schottky barrier under band-to-band illumination. The spectral photoresponse displays over six orders of magnitude discrimination between deep-ultraviolet (210 nm) and visible light (630 nm), and reveals a shoulder with an onset at 4.6 eV.
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72.40.+w Photoconduction and photovoltaic effects
73.40.Sx Metal-semiconductor-metal structures
78.40.-q Absorption and reflection spectra: visible and ultraviolet
73.30.+y Surface double layers, Schottky barriers, and work functions
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Dielectric properties of biological molecules in the Terahertz gap

Ramakrishnan Parthasarathy, Tatiana Globus, Tatyana Khromova, Nathan Swami, and Dwight Woolard

Appl. Phys. Lett. 87, 113901 (2005); http://dx.doi.org/10.1063/1.2046730 (3 pages) | Cited 15 times

Online Publication Date: 8 September 2005

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In this work, results from parallel measurements of reflection and transmission spectra of biological molecules were utilized to enable detailed and direct calculation of the refractive index and absorption coefficient spectra in the Terahertz gap. The DNA samples from herring and salmon, as well as the protein Ovalbumin sample, have been characterized. The modeling technique is described. The reflection spectra have resonance features similar to those demonstrated earlier for transmission, thereby reaffirming molecular vibrational modes in biological materials. The dispersion of refractive index and absorption coefficient is demonstrated within the Terahertz gap of 10 cm−1 to 25 cm−1. The data yielded higher refractive index and absorption coefficient for the single stranded salmon DNA than for the double stranded counterpart, with several different vibrational modes.
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87.15.M- Spectra of biomolecules
87.14.G- Nucleic acids
87.14.E- Proteins
36.20.Ng Vibrational and rotational structure, infrared and Raman spectra
33.20.Bx Radio-frequency and microwave spectra
33.20.Tp Vibrational analysis

Room-temperature atmospheric pressure plasma plume for biomedical applications

M. Laroussi and X. Lu

Appl. Phys. Lett. 87, 113902 (2005); http://dx.doi.org/10.1063/1.2045549 (3 pages) | Cited 179 times

Online Publication Date: 8 September 2005

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As low-temperature nonequilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little ozone is generated and the gas temperature, as measured by emission spectroscopy, remains at room temperature even after hours of operations. The plasma plume can be touched by bare hands and can be directed manually by a user to come in contact with delicate objects and materials including skin and dental gum without causing any heating or painful sensation.
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87.80.-y Biophysical techniques (research methods)
52.77.-j Plasma applications
52.75.-d Plasma devices
52.50.Dg Plasma sources
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Dynamic coherent backscattering in a heterogeneous absorbing medium: Application to human trabecular bone characterization

Arnaud Derode, Victor Mamou, Frédéric Padilla, Frédéric Jenson, and Pascal Laugier

Appl. Phys. Lett. 87, 114101 (2005); http://dx.doi.org/10.1063/1.2043240 (3 pages) | Cited 9 times

Online Publication Date: 7 September 2005

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We report measurements of time-resolved coherent backscattering enhancement in human trabecular bones with wide-band ultrasonic waves around 3 MHz. The experimental results show that multiple scattering takes place in the bone structure and yields an estimation of the scattering mean-free path independently from intrinsic absorption losses.
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87.63.D- Ultrasonography

Experimental determination of kinetic parameters for crystallizing amorphous NiTi thin films

Hoo-Jeong Lee, Hai Ni, David T. Wu, and Ainissa G. Ramirez

Appl. Phys. Lett. 87, 114102 (2005); http://dx.doi.org/10.1063/1.2045565 (3 pages) | Cited 6 times

Online Publication Date: 8 September 2005

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The crystallization of amorphous NiTi thin films was studied using in situ transmission electron microscopy (TEM) methods. Samples were subjected to heating conditions within the microscope and the microstructural development was monitored and recorded. The nucleation rate and the growth rate were determined experimentally by noting the number of new grains per frame and their change in size. These parameters were compared to the conventional method of kinetic analysis using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory. In it, the amount transformed is related to fitting parameters that describe the overall crystallization rate. The individual kinetic rates found directly with the TEM methods have considerable agreement with the overall rate determined by the conventional JMAK analysis. This quantitative analysis provides the groundwork for the control of microstructures and properties in NiTi shape memory alloy thin films.
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82.20.Pm Rate constants, reaction cross sections, and activation energies
64.70.D- Solid-liquid transitions
61.43.Dq Amorphous semiconductors, metals, and alloys
81.40.Gh Other heat and thermomechanical treatments
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
64.60.Q- Nucleation

Osmosis and pervaporation in polyimide submicron microfluidic channel structures

Jan C. T. Eijkel, Johan G. Bomer, and Albert van den Berg

Appl. Phys. Lett. 87, 114103 (2005); http://dx.doi.org/10.1063/1.2046727 (3 pages) | Cited 10 times

Online Publication Date: 8 September 2005

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Osmosis and pervaporation of water through the roof of all-polyimide channels of 500 nm height is described. The phenomena cause both a liquid flow in the channels and a concentration change of dissolved salt. Both effects are amplified due to the thin channel roof and the small channel height. Osmotic movement of demineralized water was observed towards a salt solution and towards ethanol and isopropanol. Water movement by pervaporation was observed from a salt solution towards the atmosphere. Flow velocities of up to 70 μm/s were generated in the channels. The results are in accordance with predictions from the solution-diffusion model for membrane transport. The observed phenomena can be applied in a nanofluidic osmotic pump or for an osmotic or pervaporative concentrator.
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82.39.Wj Ion exchange, dialysis, osmosis, electro-osmosis, membrane processes
64.70.F- Liquid-vapor transitions
47.60.-i Flow phenomena in quasi-one-dimensional systems

Two-dimensional hydrodynamic focusing in a simple microfluidic device

Claire Simonnet and Alex Groisman

Appl. Phys. Lett. 87, 114104 (2005); http://dx.doi.org/10.1063/1.2046729 (3 pages) | Cited 35 times

Online Publication Date: 8 September 2005

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Two-dimensional flow focusing in pressure-driven flow is demonstrated in a microfluidic device made of a single cast of a silicon elastomer. A stream injected into the device is shaped to a variety of rectangular profiles. A flow of particles is focused into a thin layer with homogeneous velocity. A blob of dye injected into a microchannel is transported over a long distance with minimal dispersion. The device can be integrated into lab-on-a-chip systems and used as a low-cost flow cytometry chamber.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.85.Np Fluidics
47.15.-x Laminar flows
47.60.-i Flow phenomena in quasi-one-dimensional systems
47.55.Kf Particle-laden flows

Electron emission from carbon nanotube-dispersed MgO layer

J. N. Heo, J. H. Lee, T. W. Jeong, C. S. Lee, W. S. Kim, Y. W. Jin, J. M. Kim, SeGi Yu, W. K. Yi, S. H. Park, T. S. Oh, and J. B. Yoo

Appl. Phys. Lett. 87, 114105 (2005); http://dx.doi.org/10.1063/1.2048814 (3 pages) | Cited 5 times

Online Publication Date: 9 September 2005

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A simple secondary-electron-emission (SEE)-based source was fabricated using a carbon-nanotube-dispersed MgO precursor solution. This emission source exhibits a high SEE gain as over 103. In addition, the self-sustaining current was observed even after turning off the primary electron beam, then the emission current could be modulated by a small electric field variation (1.2–2 V/μm). The electron energy spectrum of the self-sustaining emission indicates that the major character of the emission is attributed to the field-enhanced SEE rather than direct field emission.
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79.70.+q Field emission, ionization, evaporation, and desorption
79.20.Hx Electron impact: secondary emission
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Comment on “A simple approach to determine five thermomechanical properties of thin ductile films on an elastic substrate” [ Appl. Phys. Lett. 85, 6173 (2004) ]

Jürgen Malzbender

Appl. Phys. Lett. 87, 116101 (2005); http://dx.doi.org/10.1063/1.2043227 (1 page) | Cited 1 time

Online Publication Date: 6 September 2005

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65.40.De Thermal expansion; thermomechanical effects
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
68.60.Wm Other nonelectronic physical properties
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
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Response to ‘Comment on “A simple approach to determine five thermomechanical properties of thin ductile films on an elastic substrate”’ [ APL (2005) ]

W. M. Huang, Y. Y. Hu, and L. An

Appl. Phys. Lett. 87, 116102 (2005); http://dx.doi.org/10.1063/1.2043228 (1 page)

Online Publication Date: 6 September 2005

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Show PACS
65.40.De Thermal expansion; thermomechanical effects
68.60.Wm Other nonelectronic physical properties
68.60.Bs Mechanical and acoustical properties
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
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