bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of polymer-electrode interfaces in polymer light-emitting diodes using electrical impedance spectroscopy
Authors: van Dijken A. , Hulea I.N. , Brom H.B. , Brunner K. 
Published: April 2011

ABSTRACTElectrical impedance spectroscopy is used to show that time-dependent charge trapping processes occur in double-layer polymer light-emitting diodes based on poly(ethylene-dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) and poly(p-phenylene vinylene) (PPV). No time-dependent charge trapping processes are observed in single-layer devices based on PPV only. Furthermore, in double-layer devices based on poly(2,7-spirofluorene) (PSF) instead of PPV, such processes are also absent. Traps are probably created in the PPV layer close to the PEDOT:PSS interface due to chemical reactions that occur specifically between PEDOT:PSS and PPV.
New Surface Functional Metal Powders for Anisotropic Conductive Film Materials in Electronic Package Application
Authors: Huang Shu-Chen , Li Hsun-Tien , Chen Kai-Chi , Lee Tzong-Ming 
Published: April 2011

ABSTRACTNew metal powders containing organic thin film layer with multi-functional properties are prepared and used in the manufacturing of anisotropic conductive film (ACF) material for electronic package application. The organic thin film layer possesses both insulating property and thermo-compressed flowable property. The former insulating property ensures metal powder to have good insulation property at room temperature, and the latter thermo-compressed flowable property maintains the electric conductance of ACF material after high temperature compression process. Besides, the organic thin film layer also exhibited good steric hindrance to enhance the dispersion and anti-settling of metal powers in resin matrix. The functional organic groups on the surface thin film will also improve the interface adhesion between metal powder and resin matrix. Such metal powder with surface chemical modification is suitable for electronic material application, for example, anisotropic conductive film (ACF).
An Equivalent Circuit Approach to Evaluating Conductivity of Polymer-Filler Composites
Authors: Skorokhod Vladislav 
Published: April 2011

ABSTRACTAn equivalent circuit model of electrical conduction in polymer-filler particulate composites was developed in this study. The equivalent circuit was constructed for an individual composite particle with a sub-monolayer of conductive filler, where the filler particles play the role of circuit nodes, and inter-particle contacts are represented by resistors between the nodes. The mathematical representation of the equivalent circuit in the form of a linear system of equations for nodal potentials was solved numerically with Matlab software to calculate conductance of the composite as a function of the amount of conductive filler, filled fraction of the monolayer, filler-to-matrix size ratio and the degree of structuredness (non-randomness) of the filler material. Additionally, percolation concentrations and statistical distributions of composite conductance were calculated as functions of the filler-to-matrix size ratio.
Electrophysical Properties Of Polymers With Implanted Amorphous Single - Component Metals
Authors: Malkhasyan R. , Krmoyan R. , Kosyan V. 
Published: April 2011

ABSTRACTFor the last years, especially after the creation of conducting polymers, much prominence has been given to the works on creation and working out the new technologies of implantation of different metals and, on the whole, inorganic components into the structure of different polymers.Of special interest are rapidly developing researches in the field of creation and application of different nanomaterials also including metals in the processes of synthesis of different polymers.The data on electrophysical properties of polyvinyl acetate with doping amorphous molybdenum, obtained for the first time in SPE “ATOM” of Armenia, are being presented and discussed for the first time in the given paper.It is shown, that the dopes of amorphous nanosize molybdenum and crystalline nanosize molybdenum in the process of polymerization lead to its implantation into the structure of polymer. Amorphous molybdenum practically always lowers substantially electrical resistance of composite materials.
Blood Compatibility of Metal Oxide Layers on Stainless-steel
Authors: Tsuru Kanji , Takemoto Shinji , Yamamoto Tatsuhiro , Hayakawa Satoshi , Osaka Akiyoshi , Takashima Seisuke 
Published: April 2011

ABSTRACTWe examined blood compatibility of titanium oxide layer on stainless-steel (SUS316L). The oxide layers with varied thickness were yielded on SUS316L plates by dip-coating of sol-gel solution starting from tetraethyltitanate. The blood compatibility was evaluated in term of platelet adhesion using platelet rich plasma. With increase in the thickness of the oxide layer, the number of adherent platelets decreased rapidly, reached minimum around 150nm. This indicated that the thickness of titanium oxide layer affected platelet adhesion.
Characteristics of Cu/C Films on Polymer Substrate Prepared by Room Temperature ECR-MOCVD Coupled with Periodic DC Bias
Authors: Lee Joong Kee , Ko Hyungduk , Hyun Jin , Byun Dongjin , Cho Byung Won , Park Dalkeun 
Published: April 2011

ABSTRACTCu/C films were prepared at room temperature under Cu(hfac)2-Ar-H2 atmosphere in order to obtain metallized polymer by using ECR-MOCVD (Electron Cyclotron Resonance Metal Organic Chemical Vapor Deposition) coupled with periodic DC bias system. Room temperature MOCVD was possible when periodic negative voltage was applied on the polymer substrate. The periodic negative voltage induces ions and radicals to have nucleation reaction on the surface of the substrate. Formation of Cu/C films strongly depends on the periodic negative pattern of DC bias and the electric sheet resistance of the films was controlled from 108 to 100ohm/sq ranges by process parameters such as microwave power and magnet current. The increase in microwave power and magnet current brought on copper-rich film formation with low electric resistance. On the other hand carbon-rich films with high sheet electric resistance were prepared with decreased values for process parameters aforementioned.
Influence of Mechanical Rubbing of Polyhexylthiophene Layers on the Field-Effect Mobility using Differently Treated Isolator Surfaces
Authors: Heil H. , Finnberg T. , Schmechel R. , von Seggern H. 
Published: April 2011

ABSTRACTThis paper reports on the influence of the field-effect mobility of transistors based on regioregular head-to-tail coupled poly (3-hexylthiophene) by mechanically induced alignment on differently treated insulator surfaces. It is demonstrated that on hydrophilic insulator surfaces mechanical rubbing of the polyhexylthiophene layers perpendicular to the source drain contacts can increase the field-effect mobility whereas rubbing parallel to the source drain contacts results in a reduced mobility. In contrast it is shown that in transistors with a hydrophobic insulator surfaces, which show much higher mobilities no further improvement can be achieved. The rubbing induced polymer alignment is deduced from optically polarized transmission spectroscopy on polymer-coated quartz glass substrates. The different behavior of the field-effect mobility will be explained in terms of different degrees of crystallinity.
Nanoscale 3D Chemical Mapping by Spectroscopic Electron Tomography
Authors: Möbus Günter , Doole Ron C. , Inkson Beverley J. 
Published: April 2011

ABSTRACTElectron Tomography is shown to be applicable to problems of materials science if a contrast mechanism is used which provides a projection relationship for crystals not depending on lattice plane orientation. Energy filtered TEM (EFTEM) in its mode of electron spectroscopic imaging (ESI) and STEM-EDX-Mapping are, subject to limitations, suitable image formation techniques. The spectroscopic operation not only allows to overcome Bragg scattering artefacts, but offers the possibility of recording 4-dimensional data (volume and energy) of a region of interest, otherwise only known from NMR and XAS/XANES tomography at larger length-scales and from field-ion microscopy (atom probe) under restrictive conditions.
Quantification of Displacement Fields from Lattice Images (HREM) and Electron Exit Waves in Nanostructured Composite Oxides
Authors: Calderon H. A. , Huerta A. , Kisielowski C. , Kilaas R. 
Published: April 2011

ABSTRACTOxide composites have been produced by means of mechanical milling and sintering. Such materials consist of magnetic particles embedded in an insulating oxide matrix, which can have application as magnetic wave absorbers. Different systems have been investigated including MgO-MgFe2O4, FeO-Fe3O4 and other more complex ferrites. Milling induces the formation of a solid solution of cations and oxygen. Depending on temperature and system, sintering can produce a particle dispersion or simply the starting of the corresponding phase transformation. Spark plasma sintering was performed between 773 and 1373 K in order to reduce both processing time and temperature. High resolution (HREM) and conventional transmission electron microscopy show that an spinodal decomposition takes place in the system FeO-Fe3O4 during transformation from the solid solution.Generally the oxygen lattice is unique throughout the material but there is a distinctive distribution of cations giving rise to a particle dispersioGn having an spinel structure in a insulating matrix with a NaCl cubic structure.
Micro Raman Spectroscopy of Silicon Nanocrystals Produced by Picosecond Pulsed Laser Ablation
Authors: Wu M. H. , Mu R. , Ueda A. , Henderson D. O. , Vlahovic B. 
Published: April 2011

ABSTRACTPulsed laser ablation has been used to produce silicon nanocrystals. Variation of the laser fluence, backing gas type and pressure result in nanocrystals with controllable size distributions. Properties of nanocrystals produced with this method also depend on the distance of the nanocrystal from the center of the laser plume. Correlated atomic force microscopy and in-situ micro-Raman measurements confirm that particle size decreases as distance from the plume center increases. Silicon peaks in the micro raman spectra taken at increasing distance from plume center show considerable differences in both center energy and width. Confocal micro raman spectra from thicker (> 10 micron) samples show little variation with depth, in contrast with porous silicon samples.
Design and Analysis of Microcantilevers for Biosensing Applications
Authors: Zhang Xuan , Yang Mo , Ozkan Cengiz S. 
Published: April 2011

ABSTRACTThe primary deflection due to the chemical reaction between the analyte molecules and the receptor coating, which produces surface stresses on the receptor side is analyzed. The resonance frequency of microcantilevers is very sensitive to the properties of the microcantilever surface. Biosensing experiments based on resonance frequency shift are presented, which show that the results strongly depend on the interaction of specific analyte molecules with the receptor surface.
Reproducibility of Nano- and Micro-Scale Multi-Point Probe Sheet Resistance Measurements
Authors: Petersen Christian L. , Worledge Daniel , Petersen Peter R. E. 
Published: April 2011

ABSTRACTWe have investigated the reproducibility of micro- and nano-scale measurements of sheet resistance performed with micro-fabricated multi-point probes. The probes consisted of Au coated SiO2 cantilevers extending from a Si base. The measurements were done with a four-point probe technique on thin Au films, the probe electrode spacing ranging from 18 μm to 1.5 μm. We find that the standard deviation of repeated sheet resistance measurements ranges from 0.2% at 18 μm spacing to 2.6% at 1.5 μm spacing. It is inversely proportional to the probe electrode spacing. This behaviour is expected if the resolution of the measurements is governed by the positional errors of the probe electrode tips. The corresponding standard deviation of the probe tip positions (in both lateral directions) is calculated to be approximately 20 nm. We argue that these positional errors depend on the probe cantilever amplitude at the time of contacting the surface. The amplitude is inversely proportional to the square root of the cantilever spring constant, indicating that stiff cantilevers give the best reproducibility. We estimate the limiting reproducibility of multi-point probes with nano-scale electrode spacing.
Analytical and High-Resolution TEM Characterizations for Nanoscale Fractured Interfaces in Deep-Subquarter-Micron 256MBit DRAM Devices
Authors: Zhao Wei 
Published: April 2011

ABSTRACTInterfaces, contacts, and homo- or hetero-junctions are critical components in nanometer dynamic random access memory (DRAM) semiconductor devices. With shrinkage in device dimensions, interfacial analysis by TEM becomes more and more challenging, especially in the case of investigating failure mechanisms for nanoscale FRACTURED INTERFACES where electronic signatures found to be open. In this article, fractured interfaces at several C1-type contacts (a path between a Bitline and a Metal 1 interconnector) in a deep-subquarter-micron 256Mbit DRAM device were investigated by a JEOL 2010F analytical transmission electron microscope (TEM) with field-emission gun (FEG) running at 200KV. Considering the difficulty to exactly focus the fractured nano-scale interfaces at sufficiently high magnifications, high-resolution TEM (HR-TEM) and analytical scanning transmission electron microscopy (STEM) coupled with x-ray energy dispersive spectroscopy (XEDS) elemental linescan techniques were employed to provide supplemental information from difference prospects. An in-depth understanding for the nanoscale interfacial fracture mechanisms was established, and a simple model is initiated accordingly.
A scanning tunneling microscopy and potentiometry study of epitaxial thin films of La0.7Ca0.3MnO3
Authors: Paranjape Mandar , Shantha Shankar K. , Raychaudhuri A.K. , Mathur N.D. , Blamire M.G. 
Published: April 2011

ABSTRACTTo investigate the role of grain boundaries and other growth related microstructure in manganite films, a scanning tunneling microscope is used to simultaneously probe surface topography and local potential distribution under current flow at nanometer level in films of epitaxial thin films of La0.7Ca0.3MnO3deposited on single crystal SrTiO3and NdGaO3substrate by laser ablation. We have studied two types of films strained and strain relaxed. Thin (50nm) films (strained due to lattice mismatch between substrate and the film) show step growth (unit cell steps) and have very smooth surfaces. Relatively thicker films (strain relaxed, thickness 200nm) do not have these step growths and show rather smooth well connected grains. Charge transport in these films is not uniform on the nanometer level and is accompanied by potential jumps at the internal surfaces. In particular scattering from grain boundaries results in large variations in the local potential resulting in fields as high as 104-105V/cm located near the grain boundaries. We discuss the role of local strain and strain inhomogeneties in determining the current transport in these films and their resistance and magnetoresistivity. In this paper we attempt to correlate between bulk electronic properties with microscopic electronic conduction using scanning tunneling microscopy and scanning tunneling potentiometry.
Surface Modification and Optical Behavior of Tio2 Nanostructures.
Authors: Prokes S.M. , Carlos W.E. , Gole James L. , She Chunxing , Lian T. 
Published: April 2011

ABSTRACTTiO2 is a very important material from the perspective of photocatalytic applications, but due to its 3.2 eV bandgap, it is not possible to make this material efficient under visible illumination. Anatase TiO2 nanoclusters in the 3 – 30 nm range have been formed by a wet chemical technique and surface modified in order to enhance the absorption of visible light. Nitridation of the highly reactive TiO2 nanosphere surface has been achieved by a quick and simple treatment in alkyl ammonium compounds and the metallization of this surface has been achieved by electroless plating. Although the structure of the resultant material remains anatase, some of the treated material exhibits strong emission between 550–560 nm, which red shifts and drops in intensity with aging in the atmosphere. Electron Spin Resonance performed on these samples identify a resonance at g=2.0035, which increases significantly with the nitridation step. This resonance is attributed to an oxygen hole center created near the surface of the nanoclusters, which correlates well the noted optical activity.
Formation, Mechanical and Electrical Properties of Ni-based Amorphous alloys and their Nanocrystalline Structure
Authors: Sun Xiangcheng , Zhao Tiemin 
Published: April 2011

ABSTRACTA Ni-based amorphous alloy in Ni60Ti20Zr20 system was prepared by melting spinning. The glass transition temperature (Tg) was as high as about 760 K, the supercooled liquid region was quite wide, ΔTx = 50 K (ΔTx= Tx-Tg, Tx crystallization temperature), and the reduced glass transition temperature (Tg/Tm) was 0.60. The amorphous alloys exhibited a high tensile strength (of= 1015 MPa) at room temperature. The electrical conductivity obeyed a T12 law over the range of 15 K< T < 300 K, which can be explained by an electron-electron interaction model. After annealing the amorphous alloy into primary crystallization, a nanocomposites consisted of metastable Ti2Ni and Zr2Ni nanophases with size less than 15 nm embedded in the amorphous matrix was appeared.
Simulation of Morphology and Surface Vibration in Copper and Gold Nanoparticles
Authors: Kogure Y. , Kato Y. , Nozaki T. , Doyama M. 
Published: April 2011

ABSTRACTFormation and vibrational states in nanoparticles have been investigated by means of molecular dynamics simulation. The embedded atom method potentials for Cu and Au were adopted to express the interaction between atoms in the crystals. The nanoparticles were formed by cooling the atomic systems of molten states. Surface morphology of the nanoparticles were represented by highlighting the surface atoms, which were distinguished by the potential energy. Simulated surface morphology is not so symmetric as natural nanoparticles. The radial distribution function and the cross sectional view of the particles were also derived to characterize the internal structure. Thermal vibration of sample atoms at elevated temperatures was analyzed and the power spectra were calculated. Excitation of phonon mode is seen in the spectra.
A Study of Hydrogen Adsorption in Pretreated Nanocarbon
Authors: Lee Sang Moon , Ohshima Satoshi , Uchida Kunio , Yumura Motoo 
Published: April 2011

ABSTRACTA thermal treatment was applied with CO2 and air for the development of a porous structure. Adsorption isotherms of nitrogen were measured on well-characterized Ni-C nanoparticles. The thermal treatment with CO2 increased the total surface area and micropore volume. In addition, the thermal treatment with CO2 increased the hydrogen adsorption.
Synthesis and Characterization of Metal Nanoparticles and the Formation of Metal-Polymer Nanocomposites
Authors: Pradhan Anshu A. , Ismat Shah S. , Pakstis Lisa 
Published: April 2011

ABSTRACTMetal nanoparticles are highly prone to oxidation due to their high surface energy and affinity for oxygen which can lead to the complete oxidation of the particles. Studying and utilizing the unique properties of metal nanoparticles requires minimizing their interaction with the atmosphere. We have used the co-condensation technique to synthesize suspensions of metal nanoparticles in isopropanol. The solvent protects the nanoparticles from the atmosphere and minimizes agglomeration of the nanoparticles. The particles showed a lognormal distribution and the average particle size was below 20nm. Polymer-metal nanocomposites were made by dispersing the metal nanoparticles in PMMA matrix by spin coating and solution casting. Adherent films, fibers and free standing films could be obtained by varying the process conditions. The SEM images show that the nanoparticles in the spun coated films were non-agglomerated and well dispersed over a wide area. Morphology of the spun coated films was different from the solution cast films. Electrically conducting films having interconnected silver particle network could be obtained. Cytotoxicity studies show that the silver nanoparticles and the PMMA-Ag nanocomposite films are antibacterial in nature. We have also dispersed the nanoparticle into pump oil and measured the thermal conductivity of the resultant mixture. The thermal conductivity of the oil could be increased by over 50% by adding an extremely small fraction of the silver nanoparticles.
Interfacial Control of Creep Deformation in Ultrafine Lamellar TiAl
Authors: Hsiung L. M. 
Published: April 2011

ABSTRACTSolute effect on the creep resistance of two-phase lamellar TiAl with an ultrafine microstructure creep-deformed in a low-stress (LS) creep regime [where a nearly linear creep behavior was observed] has been investigated. The resulted deformation substructure and in-situ TEM experiment reveals that interface sliding by the motion of pre-existing interfacial dislocations is the predominant deformation mechanism in LS creep regime. Solute segregation at interfaces and interfacial precipitation caused by the segregation result in an increase of creep resistance in LS creep regime.
Red Shift in Optical Absorption Tail and Superparamagnetism of γ- Fe2O3 Nanoparticles in a Polymer Matrix
Authors: Vassiliou John K. , Otto Jens W. , Mehrotra V. , Davis J. J. 
Published: April 2011

ABSTRACTWell defined spherical particles of γ- Fe2O3 have been synthesized in the pores of a polymer matrix in the form of beads by an ion exchange and precipitation reaction. The particle size distribution is a gaussian with an average diameter of 80 A. The DC magnetic susceptibility and the magnetization of the nanocomposite has been measured between 4 and 300 K using a Faraday balance and a magnetometer, respectively. The magnetic measurements demonstrate that the particles are superparamagnetic with a blocking temperature Tb about 55 K. The optical absorption edge of the mesoscopic system is red shifted with respect to single crystal films of γ-Fe2O3 with an absorption tail extended deeply in the gap. Although lattice distortion and existence of excitonic states in the gap can explain the absorption behavior, the red shift can successfully be explained by the quantum confinement of an electron-hole pair in a spherical well.
Modeling Combined Thermal, Electrical, Optical and Mechanical Response for MEMS Spectroscopic Gas Sensor Based On Photonic Crystals
Authors: Greenwald Anton C. , Pralle Martin U. , McNeal Mark P. , Moelders Nicholas , Puscasu Irina , Daly James T. , Johnson Edward A. 
Published: April 2011

ABSTRACTA new type of gas sensor was developed that combines the principles of bolometric infrared detectors with photonic crystals.1,2 This paper describes a quantitative model used to optimize the materials, geometry, and electrical properties of this suspended membrane MEMS device. Fundamentally the model is concerned with the thermal response of the device using temperature dependent thermal conductivity, specific heat, and electrical resistance to calculate conduction, convection, and radiation losses for a negative temperature coefficient of resistance material. Variations in the electrical drive circuit, dc and ac response, low and high frequency sinusoidal and random noise, along with an exacting calculation of expected signal were used to improve design. The model follows the time evolution of the system. We show how look-up tables with scaling (derived from exact, off-line finite element models for thermal conduction, spectral emission, etc.) provided sufficiently accurate estimates with rapid calculation to enable running the model on a standard PC type computer. The simulations matched the experimental results, accurately predicted the unstable operating regimes, and maximized the signal to noise ratio for the device.