bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient Detector of the Neurotransmitter ACh and AChE Inhibitors
Authors: Goykhman Ilya , Korbakov Nina , Bartic Carmen , Borghs Gustaaf , Spira Micha E. , Shappir Josef , Yitzchaik Shlomo
Published: April 2011

Among the variety of applications for biosensorsone of the exciting frontiers is to utilize those devices as post-synaptic sensing elements in chemical coupling between neurons and solid-state systems. The first necessary step to attain this challenge is to realize highly efficient detector for neurotransmitter acetylcholine (ACh). Herein, we demonstrate that the combination of floating gate configuration of ion-sensitive field effect transistor (ISFET) together with diluted covalent anchoring of enzyme acetylcholinesterase (AChE) onto device sensing area reveals a remarkable improvement of a four orders of magnitude in dose response to ACh. This high range sensitivity in addition to the benefits of peculiar microelectronic design show, that the presented hybrid provides a competent platform for assembly of artificial chemical synapse junction. Furthermore, our system exhibits clear response to eserine, a competitive inhibitor of AChE, and therefore it can be implemented as an effective sensor of pharmacological reagents, organophosphates, and nerve gases as well.
Hydrogel Based Composite Materials for Chemical, Biological and Medical Sensing Applications
Authors: Porter Timothy L. , Vail Tim , Reed Jim , Stewart Ray
Published: April 2011

Embedded piezoresistive microcantilever (EPM) sensors provide a tiny, low-cost, and robust platform for the detection of chemical or biological analytes. New sensing applications become potentially available as the design or synthesis of new sensing materials for EPM instruments are studies. In this study, we report on the detection of hydrogen fluoride gas (HF) in air, and in a medical application, the measurement of human hydration levels. Two sensing materials characterize these applications, thiolated gold nanoparticles in a keratin matrix (HF), and a crosslinked PVA-based hydrogel in the hydration application.
Light-Matter Interaction of Strong Laser Pulses in the Micro-, Nano-, and Pico-second Regimes
Authors: Agren Hans , Welinder Pontus , Erlandsson Robert , Henriksson Johan , Norman Patrick , Ågren Hans
Published: April 2011

Light propagation in a medium is sensitively dependent on the shape and intensity of the optical pulse as well as on the electronic and vibrational structure of the basic molecular units. We review in this paper results of systematic studies of this problem for isotropic media. Our theoretical approach|the quantum mechanical{electrodynamical (QMED) approach is based on a quantum mechanical account of the many-level electron-nuclear medium coupled to a numerical solution of the density matrix and Maxwell's equations. This allows to accommodate a variety of nonlinear e ects which accomplish the propagation of strong light pulses. Particular attention is paid to the understanding of the role of coherent and sequential excitations of electron-nuclear degrees of freedom. The QMED combination of quantum chemistry with classical pulse propagation allows to estimate the optical transmission from cross sections of multi-photon absorption processes and from considerations of propagation e ects, saturation and pulse e ects. Results of the theory suggest that in the nonlinear regime it is often necessary to account simultaneously for coherent one-step and incoherent step-wise multi-photon absorption, as well as for o -resonant excitations even when resonance conditions prevail. The dynamic theory of nonlinear propagation of a few interacting intense light pulses is here highlighted in a study of the optical power limiting with platinum-organic molecular compounds.
Influence of TiO2 on Second Harmonic Generation in Disperse Red -1 doped Organic-Inorganic Hybrid Thin Films
Authors: Zha Congji , Luo Xinshi , Samoc Anna , Rode Andrei , Luther-Davies Barry
Published: April 2011

Disperse Red 1 (DR1) doped TiO2-SiO2 inorganic-organic hybrid polymers were prepared by an anhydrous sol-gel process and second harmonic generation (SHG) of the fundamental 1053nm in these polymeric thin films was measured using Maker-fringe method. The nonlinear optical activity of DR1 in the thin films was studied by corona poling at different temperature (from room temperature to 140°C), and the stability of SHG after switching off corona power was evaluated by analyzing the SHG decay dynamics. Experimental results showed that the stability of the SHG of DR1 significantly increases with the cross-linkage degree of the TiO2SiO2 hybrid polymer network, and that the second harmonic coefficient d33 increases as the DR1 concentration increases. TiO2-doping can promote the polymerization of unsaturated C=C double bonds in the hybrid thin films during in-situ hot poling, enhancing the cross-linkage of the network of the hybrid material, and resulting in a great improvement of the stability of SHG. The excellent stability of second harmonic generation in the hybrid polymer thin films suggests that TiO2-doped inorganic-organic hybrid polymer is promising for chromophore doping for nonlinear optical applications.
Excitation of Coherent Phonons in Crystalline Bi: Theory for Driving Atomic Vibrations by Femtosecond Pulses
Authors: Boschetto Davide , Gamaly Eugene G. , Rode Andrei V. , Garl Thomas , Rousse Antoine
Published: April 2011

In this paper we show time-resolved experiment with 35 fs resolution on bismuth single crystal, for which very high sensitivity detection system has been used. Coherent and incoherent lattice dynamics as well as electrons dynamics can be clearly seen into the reflectivity changes. The complex behaviour of the reflectivity could not be explained in the light of the existing theories. Therefore, we developed a new theory, starting from the very basic principle of laser-matter interaction, which is in good agreement with experimental results. Two main results will be shown: the coherent phonon is excited by the temperature gradient; the changes in reflectivity are related directly to the changes in electron-phonon collision frequency.
A Simple Phenomenological Model for Growth of Nanodots with “Magical Sizes” Stabilized by Quantum Size Effect
Authors: Ristolainen Heikki Juha Tapani , Koponen Ismo
Published: April 2011

In deposition of Pb atoms on Cu(111) or Si(111) surface growth of tower-shaped nanostructures is observed. This nanotower growth is caused by structure height dependent energetics, resulting from the quantum size effects (QSE) due to the vertical electron confinement in nanotowers. In this report we present a “wedding cake” -type phenomenological model describing the time evolution of nanostructures. The model reproduces the typical morphologies of nanotowers. The results demonstrate that nanohuts are formed by downward mass currents, due to the downward diffusion of adatoms. Also the stable layers due to the quantum size effects (QSE) can be modelled with a suitable choice of model parameters. In the case of altering stabilities of layers, simultaneous bi-layer growth takes place. The results are in agreement with experimental observations.
Sol-Gel Derived SnO2 Nanometric Fibers
Authors: Saal Kristjan , Tätte Tanel , Paalo Madis , Talviste Rasmus , Vlassov Sergei , Kink Ilmar
Published: April 2011

The applicability of Sn(OBu)4 based viscous oligomeric concentrates in fabrication of thin oxide fibers and needles is demonstrated. Influence of several crucial parameters like viscosity of the concentrate, humidity of surrounding atmosphere and pulling speed on formation of the structures is discussed. We show that the method enables to obtain fibers less than a micron in diameter and needles with tip radii down to 15 nm, i.e. in range that is of considerable interest for many nanotechnological applications.
Electron-Beam Induced Growth of Silica Nanowires and Silica/Carbon Heterostructures
Authors: Solá Francisco , Resto Oscar , Biaggi-Labiosa Azlin M , Fonseca Luis F
Published: April 2011

A novel synthesis of silica nanowires and silica/carbon heterostructures by electron beam irradiation on porous silicon films was investigated. The method allows us to monitor the growth process in real time at atomic scales. Depending on the electron dose we obtain nanowires with diameters in the range of 15-49nm and lengths up to 500 nm. We found that the adequate electron dose was between 0.01 Acm-2 and 2 Acm-2. Additional electron dose causes plastic and failure deformations in the silica nanowires. A growth model consistent with our findings is presented that involves the flow of mass from the substrate to the nanowire driven by the local electric fields. Heterostructures showing a nanopalm-like shape are obtained after exposing the silica nanowire to poor vacuum conditions in which carbon aggregation from the surrounding gas is promoted by the local electric fields enhanced at the tip of the silica wires.
In Situ Investigation of the Silver-CTAB System
Authors: Gray Jeremy , Orme Christine , Du Danxu , Srolovitz David
Published: April 2011

Recent research has shown that biologically inspired approaches to materials synthesis and self-assembly, hold promise of unprecedented atomic level control of structure and interfaces. In particular, the use of organic molecules to control the production of inorganic technological materials has the potential for controlling grain structure to enhance material strength; controlling facet expression for enhanced catalytic activity; and controlling the shape of nanostructured materials to optimize optical, electrical and magnetic properties. In this work, we use organic molecules to modify silver crystal shapes towards understanding the metal-organic interactions that lead to nanoparticle shape control.

Using in situ electrochemical AFM (EC-AFM) as an in situ probe, we study the influence of a cationic surfactant cetyltrimethylamminobromide (CTAB) on Ag growth during electrochemical deposition on Ag(100). The results show that the organic surfactant leads to a unique crystal growth habit. With CTAB present in the growth solution, Ag islands grow in a truncated pyramidal shape. To understand the shape evolution of the Ag islands, we utilize electron backscatter diffraction (EBSD) in conjunction with microscopic ellipsometry to characterize the facet-specific binding of the organic molecules to large-grained polycrystalline Ag substrates.
Schottky-Barrier Si Nanowire MOSFET: Effects of Source/Drain Metals and Gate Dielectrics
Authors: Yang Weifeng , Whang Sungjin , Lee Sungjoo , Zhu Haichen , Gu Hanlu , Cho Byungjin
Published: April 2011

We fabricated and studied the performance of Schottky-Barrier Si nanowire FETs (SiNW FET) by using Vapor-liquid-solid (VLS) grown Au-catalyzed SiNWs (20 nm). These devices were formed on various gate dielectrics (HfO2 or Al2O3) with different metal Source and Drain (S/D) regions (Pd, Ni). P-type behavior was observed and high Ion/Ioff ratio (~105) was achieved from undoped SiNW FETs. Besides, no ambipolar transportation was observed in our devices performance. This is possibly due to the small schottky barrier height for hole carriers at Source sides formed by high work-function metal. Furthermore, low subthreshold slope as 68mV/decade was obtained from SiNW FETs integrated with Ni S/D and Al2O3 High-¦gate dielectric.
New Palladium Nanomaterials for Catalysis: Mechanisms Controlling Formation and Evolution of Nanostructures in a Seed-Mediated Synthesis
Authors: Bisson Laure , Boissière Cédric , Sanchez Clément , Thomazeau Cécile , Uzio Denis
Published: April 2011

Metallic nanoparticles are commonly used as the active phase of heterogeneous catalysts. Today, a current issue in catalysis research is to determine whether a specific crystallographic plane of the metallic nanoparticle is responsible for activity and selectivity properties in a structure sensible reaction. Following this purpose, metallic nanoparticles with specific morphologies have been studied. In the present work, palladium nanostructured particles are prepared in a surfactant mediated aqueous medium by a seeding growth approach, and present various morphologies : rods, tetrahedra and/or bipyramides, cubes, icosahedra... Synthesis of these nanoparticles and observation of their growth by a detailed Transmission Electron Microscopy study will be presented. We provide evidence that nucleation and growth of these particles are dominated by an aggregative mechanism. Moreover, upon ageing nanostructured particles undergo a ripening process to spherical morphology, attributed to an oxidative etching.
Vapor-phase Growth of High-quality ZnO Micro- and Nano-structures
Authors: Morales Monica , Look D. C. , Farlow G. C. , Claflin B.
Published: April 2011

Micro- and nano-structures of ZnO have been grown on substrates from flowing carrier gases in a tube furnace. We have investigated how variations in the carrier gas composition, gas flow rate and the position of the substrate control the formation and the morphology of the nanostructures. The source material was pure zinc powder evaporated in the temperature range 500ºC to 650ºC in flowing Ar plus oxygen at atmospheric pressure. It was found that precise control of the gas composition, gas flow rate, and growth time was necessary for reliable deposition. It was also found that zinc powder must be washed to remove the surface oxide. Scanning electron microscopy (SEM) images of samples grown from a Zn powder source show forested needles approximately 100 nm in diameter by 1 micron long, and faceted rods from 500nm to 700nm thick. Photoluminescence measurements at 4 K show a dominant line at ~3.36eV with additional features at 3.32 and 3.37eV. The line widths are ~ 3.5meV, indicating good quality material. The usual green-band emission is also observed.
Optimizing Growth Rates and Thermal Stability of Silver Nanowires
Authors: Gates Byron D. , Gates Byron D.
Published: April 2011

There are multiple solution-phase approaches to synthesizing nanowires, yet some aspects of these syntheses are not well understood. Solution-phase methods are attractive for the ease of scaling to large quantities, which is a necessary step for applications utilizing nanowires. However, insight into the surface chemistry and mechanism of growth of the nanowires is essential for increasing the yield of nanowires. An improved synthesis of silver nanowires is presented along with insight into the mechanism of growth and stabilization of the nanowires. The techniques from this modified synthesis could be extended to a number of other solution-phase procedures to increase the yield of nanostructures.
Investigation on Site Density of Carbon Nanotube Forests
Authors: Liu Zhengchun , Lee Sang Hwui , Bajwa Navdeep , Ci Lijie , Kar Swastik , Ajayan Pulickel M. , Lu Jian-Qiang
Published: April 2011

We report on a method for direct measurement of site density of vertically-aligned carbon nanotubes (CNTs). Site density is an important parameter of vertically-aligned carbon nanotube forests for various applications. By freezing the CNT forests in a polymer matrix and exposing the CNT ends, we obtained the site density of vertically aligned multi-walled CNTs through SEM observation and particle counting. Site densities of multi-walled CNTs grown by two different CVD processes, ferrocene/xylene process and Fe-Al/ethylene process, were measured to be ∼10 tubes/Ým2 and ∼53 tubes/Ým2, respectively. The results of site density distributions indicate non-uniform growth of carbon nanotubes at the micrometer scale in both processes.
Low Temperature Growth and Application of Zinc Oxide Nanowires using Zinc Oxide Seeds
Authors: Sunyoung Lee , Hey Jin Myoung , Sunglyul Maeng , Sang-Hyeob Kim
Published: April 2011

The growth of ZnO nanowire arrays on a variety of substrates using a chemical wet process is presented. ZnO seeds can act as a nucleation layer for wire growth and ZnO nanowire arrays can have direct contact with a variety of substrates. The structural and optical properties of ZnO nanowire arrays grown at 90°C are investigated. FESEM and X-ray diffraction observations reveal that the crystalline ZnO nanowire arrays are preferentially oriented along the c axis. The room temperature photoluminescence (PL) measurements had shown ultraviolet peaks and a deep level peak. After annealing at 900°C for 1 min. by RTA, the deep level peak became much weaker and the band-edge emission PL was much stronger.
Fabrication of CNT/metal torsional resonator structures on GaAs
Authors: Hong Seung Sae , Bak Jung Hoon , Lee Byung Yang , Cho Sung Woon , Kim Young Duck , Hong Seunghun , Park Yun Daniel
Published: April 2011

We present a method to realize nanoelectromechanical systems (NEMS) resonator structures from carbon nanotubes (CNT)/metal layered composite structures. The method utilizes a self aligning process over a near 2-D CNT network on GaAs to realize resonator structures and a highly selective etchant, a standard citric acid/hydrogen peroxide solution, to achieve release of NEMS resonators from the substrate. We find this method along with critical point drying (CPD) to yield robust hybrid CNT/metal resonator structures with fundamental resonant frequencies in the 10 MHz range. With high reflectivity, conductivity, and bio-compatibility of metals, this fabrication method along with possible benefits of CNT have many application possibilities.
High-Current Reliability of Carbon Nanofibers for Interconnect Applications
Authors: Kitsuki Hirohiko , Suzuki Makoto , Ngo Quoc , Gleasson Kristofer , Cassell Alan M. , Ominami Yusuke , Moylan Christopher R. , Li Jun , Yang Cary Y.
Published: April 2011

We present a high-current reliability study of carbon nanofibers (CNFs) for interconnect applications. In situ scanning transmission electron microscopy (STEM) reveals structural damage to CNFs after current stress. The effect of heat dissipation on the current capacity is also discussed by using different experimental configurations. Long-time reliability tests are performed with a vertical via interconnect structure, showing promising high reliability of CNF interconnects for future electronic devices.
Versatile Metal Oxide Nanowire Devices Achieved via Controlled Doping
Authors: Dattoli Eric , Wan Qing , Lu Wei
Published: April 2011

We report on studies of field-effect transistor (FET) and transparent thin-film transistor (TFT) devices based on lightly Ta-doped SnO2 nanowires. Uniform device performance was obtained using an in situ doping method, with average field-effect mobilities exceeding 100 cm2/(V•s). Prototype fully-transparent TFT devices on glass substrates showed excellent performance metrics in terms of transconductance and on/off ratio. The combined advantages of SnO2 nanowires: namely a low cost growth process, high electron mobility, and optical transparency; make the system well suited for large-scale transparent electronics on low-temperature substrates.
ZnO Nanowire/p-GaN Heterojunction LEDs
Authors: Jacobs Heiko O. , Cole Jesse , Dabiran Amir M. , Jacobs Heiko O.
Published: April 2011

This article reports forward and reverse biased emission in vertical ZnO nanowire/p-GaN heterojunction light emitting diodes (LEDs) grown out of solution on Mg-doped p-GaN films. The electroluminescence spectra under forward and reverse bias are distinctly different. Forward bias showed two peaks centered around 390 nm and 585 nm, while reverse bias showed a single peak at 510 nm. Analysis of the current-voltage characteristics and electroluminescence spectra is presented to determine the transport mechanism and location of electron hole recombination. Reverse bias transport and luminescence are attributed to hot-hole injection from the ZnO nanowires into the GaN film through tunneling breakdown. Forward bias transport and luminescence are attributed to hole injection from the GaN into the ZnO and recombination at defect states inside the ZnO yielding distinct color variations between individual wires. Major resistive losses occurred in the GaN lateral thin film connecting to the vertical ZnO nanowires.
Electrokinetic Alignment of Polymer Microspheres for Biomedical Applications
Authors: Kunduru Vindhya , Prasad Shalini
Published: April 2011

One of the applications of clinical proteomics is the development of protein sensor platform technologies for rapid bedside detection of disease biomarkers. Multiplexed protein biomarker analysis is a new way to predict the disease earlier and monitor its progress with more specificity and accuracy. We present here the development of a prototype electrical protein biomarker detection system. It comprises of a silicon based microelectrode array also known as the sensor chip. Polystyrene beads act as the carriers or transportation agents for the proteins and provide surface area for immobilizing protein receptors (antibodies) on the surface of the sensor chip. Polystyrene “microbridge” structures are patterned on the surface of the sensor chip, such that they form conductive paths between the selected electrodes. This is achieved by the electrokinetic assembly of the antibody functionalized polystyrene beads. The electrical assembly is achieved using dielectrophoresis. The “microbridge” structures couple signals arising due to the antibody-antigen binding event that occurs when the test sample is flowed on to the sensor platform. We demonstrate the functioning of this device in the detection for an inflammation marker, namely, C-reactive protein at microgram/ml sensitivity.
Recent Advances in FIB Technology for Nano-prototyping and Nano-characterisation
Authors: Stokes Debbie J , Roussel Laurent , Wilhelmi Oliver , Giannuzzi Lucille A , Hubert Dominique HW
Published: April 2011

Combined focused ion beam (FIB) and scanning electron microscopy (SEM) methods are becoming increasingly important for nano-materials applications as we continue to develop ways to exploit the complex interplay between primary ion and electron beams and the substrate, in addition to the various subtle relationships with gaseous intermediaries.

We demonstrate some of the recent progress that has been made concerning FIB SEM processing of both conductive and insulating materials for state-of-the-art nanofabrication and prototyping and superior-quality specimen preparation for ultra-high resolution scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM) imaging and related in situ nanoanalysis techniques.
Ion Beam Lithography for Nano-scale Pattern Features
Authors: Baglin John E.E. , Kellock Andrew J. , Frommer Jane E.
Published: April 2011

With the expected availability of new tools for creating patterned ion beams, containing few-nanometer features, it is important to examine the fidelity of registering such patterns in the receiving medium, such as a photoresist layer in a lithographic fabrication process. In this paper, we report experiments exploring the characteristics of ion beam patterning of poly methyl methacrylate (PMMA) and polystyrene (PS) coatings on silicon substrates, with respect to their response as positive / negative resists to patterned low-energy H+, He+ and Ne+ beams. We examine by AFM the feature profiles thus created after solvent development of the polymer layers, and we examine the dependence of the polymer response upon ion species and fluence. Edge resolution ¡Ü20 nm is readily obtained, and broad process windows are identified in fluence ranges around 1013 ions/cm2. Proximity effects are shown to be negligible, except after exposure at very high ion fluences. Granularity within the final pattern features is shown to be a potential concern for high energy, light ion irradiations. Optimization of edge resolution is clearly possible, by appropriate selection of ion species, energy and fluence to suit the receiving medium.
Nano- and Micro-Structural Evolution of UHMWPE by Ion Beam
Authors: Calzzani F. , Chhay B. , Zimmerman R. , Oztarhan A. , Ila D.
Published: April 2011

It is important to produce uniform nano-patterns with no possibility of surface exfoliation on polyethylene devices used in medical and in aerospace industry. We studied the change in the surface morphology of polyethylene at nanoscale using MeV ion beam. We have investigated the change in the surface morphology before and after ion bombardment. We have made an attempt to change the morphology to produce a uniform surface with reduced cracks and reduced granularity. For this process we have chosen ultra-high-molecular-weight polyethylene (UHMWPE). Coupons of these materials were exposed to various fluences of MeV Ag+ions. The surface morphology and the change in the chemical structure were studied using scanning micro Raman, FTIR and AFM.
Effect of Implantation Dose and Annealing Time on the Formation of Si Nanocrystals Embedded in Thermal Oxide
Authors: Qian Cong , Zhang Zheng-xuan , Zhang Feng , Lin Cheng-lu
Published: April 2011

Photoluminescence (PL) and X-ray Photoelectron Spectroscopy (XPS) are employed to study the Si nanocrystals formed in the thermal oxide by Si+ implantation. PL results estimate the size of nanocrystals and the concentration of Pb centers in the Si-SiO2 nanocrystal-matrix interfaces. It is shown that the size of Si nanocrystals increase with implantation dose. Increasing the dose from 1×1016 to 1×1017 Si+/cm2 shifts the size of nanocrystals from ~2 nm to ~3.5nm, while prolonging the annealing time from 1h to 2h has no effect on the position of PL peak. P and Ar implantations into the SiO2 films are also investigated to suggested that the PL peak is due to implant induced chemical changes rather than implant induced damage. XPS analysis shows that the concentration of Si nanocrystals increases with Si implantation dose. Research on the annealing dependence of the forming of Si nanocrystals suggests that 1000°C annealing produces larger amount of Si nanocrystals than 1100°C annealing.
Thermal Conductivity Computation of Nanofluids by Equilibrium Molecular Dynamics Simulation: Nanoparticle Loading and Temperature Effect
Authors: Sarkar Suranjan , Selvam R. Panneer
Published: April 2011

A model nanofluid system of copper nanoparticles in argon base fluid was successfully modeled by molecular dynamics simulation. The interatomic interactions between solid copper nanoparticles, base liquid argon atoms and between solid copper and liquid argon were modeled by Lennard Jones potential with appropriate parameters. The effective thermal conductivity of the nanofluids was calculated through Green Kubo method in equilibrium molecular dynamics simulation for varying nanoparticle concentrations and for varying system temperatures. Thermal conductivity of the basefluid was also calculated for comparison. This study showed that effective thermal conductivity of nanofluids is much higher than that of the base fluid and found to increase with increased nanoparticle concentration and system temperature. Through molecular dynamics calculation of mean square displacements for basefluid, nanofluid and its components, we suggested that the increased movement of liquid atoms in the presence of nanoparticle was probable mechanism for higher thermal conductivity of nanofluids.
Combinatorial Searching for Pt-Zr-Ni Thin Film Amorphous Alloys for Glass Lens Mold
Authors: Abe Mitsuhiro , HATA Seiichi , YAMAUCHI Ryusuke , SAKURAI Junpei , SHIMOKOHBE Akira
Published: April 2011

Recently, the materials of functional optical glass lens mold have been studied. We had searched for the novel amorphous alloy having high crystallization temperature Tx using combinatorial arc plasma deposition (CAPD). In the previous work, Ru-based and Pt-based alloys were investigated. Although these amorphous alloys had high Tx of more than 973 K, they did not show good machinability. In this work, in order to progress machinability of amorphous samples, the various properties of the Pt-Zr-Ni thin film amorphous alloys were investigated. The properties of desired sample were as follows: (1) Tx exceeds 923K. (2) sf exceeds 2.0GPa. (3) Non-sticking characteristics with melting glass. (4) Good machinability.

As the process of searching for amorphous alloys, 3267 samples were deposited by CAPD. The phase and composition of the CAPD samples with thickness more than 500nm were evaluated. Thickness of the CAPD samples was measured by a white-light interferometer. Compositions were measured by an energy dispersive X-ray fluorescence spectrometer. Phases were identified by an X-ray diffractmeter. From these results, 312 amorphous compositions were found. The period of searching for amorphous composition was only about twenty days. This shows the effectiveness of CAPD.

Tx and fracture stress Ðf of the sputter-deposited amorphous samples having the same composition as amorphous CAPD samples were measured because CAPD samples were too small to evaluate thermal and mechanical properties. Tx was measured by differential scanning calorimeter. sf was measured by tensile tests using a thermo-mechanical analyzer.

At first, in order to investigate the effect of Pt-content on Tx, the PtxZr (90-x)Ni10 samples were fabricated by the sputter. Pt-content was ranged from 20 to 50 at.%. Tx increased with increasing Pt-content, and the Pt51Zr39Ni10 sample showed the highest Tx of 939K. The sample has needs to show Pt-rich composition to show Tx of more than 923K. However, sf of all sample showed less than 2GPa.

Subsequently, in order to search for Pt-rich sample having high sf, the properties of the Pt50Zr(50-x)Nix sample were investigated. Ni-content was ranged from 5 to 15 at.%. As the results, Tx increasing with increasing Ni-content. The Pt50Zr36Ni14 sample showed the highest Tx of 985 K and Ðf of 2.12 GPa.

Sticking characteristics of the Pt50Zr36Ni14 sample with melting glass were measured. Melting glass was felled in drops on the samples, and then droplet was removed without adhering to the sample. Machinability of the Pt50Zr36Ni14 sample was evaluated by cutting tests using diamond tools. Surface roughness of this sample worked was several nanometers. This result indicated that the Pt50Zr36Ni14 sample showed good machinability. From these results, it is considered that the Pt50Zr36Ni14 sample is suitable for the materials for glass lens mold.
A Calculation Method of the Deposition Profiles in Chemical Vapor Deposition Reactors Using Basis Functions
Authors: Takahashi Takahiro , Kawamura Ken , Ema Yoshinori
Published: April 2011

In this paper, we introduced a novel calculation method to reproduce deposition profiles in various types of Chemical Vapor Deposition (CVD) reactors. Robust and accurate calculations along with reduced computing cost were achieved by the method. Boundary value problems for estimating diffusion-reaction equations by iterations of numerical integrations were changed into problems of finding the linear combinations consisted of a few "basis functions", which are inherent in the reactors. The coefficients of the linear combinations were optimized by Genetic Algorithms (GA). We could demonstrate the validity of the proposed method using various examples of the reaction mechanisms and conditions.
Quantitative EELS Analysis of AlGaN Nanowires Grown by Ni Promoted MBE on Sapphire Substrate
Authors: Lari Leonardo , Murray Robert T , Gass Mhairi H , Bullough Timothy J , Chalker Paul R , Chèze Caroline , Geelhaar Lutz , Riechert Henning
Published: April 2011

Quantitative analysis of the elemental distributions within AlGaN has been investigated using electron energy loss spectroscopy in a scanning transmission electron microscopy. The nanowires were grown on c-sapphire by radio frequency plasma assisted molecular beam epitaxy. Crystallographic and compositional analyses of the nickel seeds used to promote the nanowire type growth yielded values of lattice spacings within the seeds remaining at the growth tip which were attributed to either (002) NiO, (111) Ni3Ga or (111) Ni-Ga solid solution. The seeds structures exhibited a metallic core encompassed by an oxide shell. The relative gallium and nickel concentrations were quantified by EELS analyses and were found to be consistent with the equilibrium phase α' of Ni3Ga or Ni-Ga solid solution. No nitrogen was observed within the seeds, which is predicted thermodynamically due to the instability of Ni-N compounds at the NW growth temperature used in this study. No aluminium was detected at the tip of nanowires. These measurements are compared with previous studies made concerning pure GaN nanowires. The Al distribution along the nanowire length was measured and is discussed in respect of a possible Al incorporation mechanism.
Digital Image Processing and MEB (BSE) Techniques in the Identification and Quantification of Minerals Phases Present in Cement and Concrete
Authors: Prendes Nicanor , Menéndez Esperanza
Published: April 2011

The generation processes of microscopic images in as Backscattered Scanning Electrons (BSE) are produced by complex interaction between incident electrons beam within the specimen. Different authors have correlated the energy of impact released with the mean atomic number (Z) of the phase to study, and deducing that the nature of the scattering events induced by the electron beam is strongly controlled by the Z value of them. If we compared the amount of electron backscattering with respect to response of the beam energies and so deduced a mathematical functions, for each specimen studied, and respectively by to digital images processing (based on the linear transformation of levels grey range in those energies) allows to sharpen in the discrimination and quantification of some phases in cements that, due to overlap processes, until now, could not be isolated. By means theses theoretical studios it is possible, for example, to identify interstitial cations that impinge on Z factor of phase deducing for each types of energies answer a series of mathematical functions, fitting a coefficient and across digital image techniques allows to sharpen in the discrimination and quantification of certain phases in cements that, as well, is noted in grey levels of digital image. In electron microscope have to settle down a strict work conditions (DW=10 mm, V0=20 KeV), and from a pattern specimen, found the grey level of image histogram for those working conditions, and fitting to the linear function, even if operated with BSE, the theoretic phases deduced from the EDX and the quantitative analysis of the stoichiometric formula. Given a coefficient (ç) its effective Z it's calculated; the deviation, therefore, gives the interstitial cations presence. With this tool, for example, the ettringite of gypsum is discriminates; or C-S-H products and the C3S. Once obtained the greys levels image of surface to examine and by means of threshold images process (a value of limit grey level or phase identification) he is immediate to obtain stereological relations (working with planar surfaces, which facilitate the treatment and the development of algorithms of mathematical morphology) and quantitative character phases of each phase
The information content of lattice resolved high angle tilt series of nanoparticles
Authors: Xu Xiaojing , Saghi Zineb , Inkson Beverley , Möbus Günter
Published: April 2011

Gold nanoparticles are observed by high-resolution electron microscopy over a high tilt range equivalent to tomographic data acquisition. It is demonstrated how the lattice resolved contrast can be used to identify the internal multiply-twinned microstructure, as the large number of viewing direction allows to image each of the grain-to-grain displacement vectors in at least one image. Furthermore application of tomographic reconstruction is shown after binarisation of the original images to estimate the external shape from the support of the particle in the case of convex objects.
Grain-Scale Strain and Orientation Measurements during Electromigration in Al Conductor Lines by Synchrotron X-Ray Microbeam Diffraction
Authors: Zhang Hongqing , Cargill G. S. , Ge Youzhang , Maniatty A. M. , Liu Wenjun
Published: April 2011

Al conductor lines, with Ti-Al top and bottom layers and SiO2 passivation, were stressed with current density 1.5 × 106 A/cm2at 190°C, and the strains developed during electromigration were measured in-situ by white and monochromatic beam synchrotron x-ray microdiffraction. Grain-scale deviatoric strain measurements with 0.4µm beam size and perpendicular full strain measurements with 1.0µm beam size were made repeatedly during electromigration. A strong strain gradient developed along the upstream half of the conductor lines during electromigration, although no resistance changes, voids or extrusions were seen. Orientation maps showed near-bamboo grain structure. Results from an approximate analytic model, using the Eshelby inclusion theory, are consistent with the measurement results for late-stage electromigration-induced strains.
Magnetic Structures and Magneto-volume Effects in Mn3Cu1-xGexN
Authors: Iikubo Satoshi , Kodama Katsuaki , Takenaka Koshi , Takagi Hidenori , Shamoto Shinichi
Published: April 2011

Magnetic structures in an antiperovskite system, Mn3Cu1-xGexN, with a large magneto-volume effect above x =0.15 have been studied by neutron powder diffraction measurement. The present neutron study revealed that not only a cubic crystal structure but also a Γ5g antiferromagnetic spin structure are key ingredients of the large magneto-volume effect in this itinerant electron system.
In situ X-ray Scattering Study of the Formation of Au Nano Crystals During Thermal Annealing
Authors: Noh Do Young , Ryu Ki-Hyun , Kang Hyon Chol
Published: April 2011

The transformation of Au thin films grown on sapphire (0001) substrates into nano crystals during thermal annealing was investigated by in situ synchrotron x-ray scattering and ex situ atomic force microscopy (AFM). By monitoring the Au(111) Bragg reflection and the low Q reflectivity and comparing them with ex situ AFM images, we found that polygonal-shape holes were nucleated and grow initially. As the holes grow larger and contact each other, their boundary turns into Au nano crystals. The Au nano crystals have a well-defined (111) flat top surface and facets in the in-plane direction.
Influence of Self-Assembled Organic Thin Film Monolayer on Ambient Copper Surfaces Oxidation
Authors: Platzman Ilia , Haick Hossam , Tannenbaum Rina
Published: April 2011

Qualitative and quantitative studies of the oxidation of molecularly modified polycrystalline copper (Cu) thin films upon exposure to ambient air conditions for long periods (on the order of several months) are reported in this work. Thin films of Cu, prepared by thermal evaporation, were analyzed by means of x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) to gain an understanding on the growth mechanism of oxide on bare and molecularly modified Cu surfaces. The results from all techniques points for an unstable behavior of bare Cu surfaces characterized in very fast and continuous growth of Cu oxide layers during first 60 days of exposure to overall 6 nm oxide thickness. However, Cu films prepared under the same conditions, but covered with a self-assembled organic thin film layer of 1,4-phenylene diisocyanide (PDI) molecules adsorbed from solution, showed a decrease in the thickness of the copper oxide layer on the Cu surface. Our findings imply that chemisorbed PDI monolayers can serve as protective coatings for Cu.
Degradation in iTMC OLEDs
Authors: Soltzberg Leonard J. , Goldberg Velda , Kaplan Michael D. , Bankowski Heather , Browne Shannon , Concannon Heather , Damour Megan , Green Samantha , Hendrickson Elthea , Huang HengLian , Liu Virginia , Piirainen Lindsey , Reel Suwathna , Malliaras George G. , Slinker Jason D. , Bernhard Stefan
Published: April 2011

The processes underlying degradation of organic light emitting diodes (OLEDs) are gradually becoming understood. In ruthenium-based ionic transition metal complex (iTMC) OLEDs, a dimeric species forms during device operation that quenches light emission [1]. Water has been implicated in this degradation process [2]. We report recent studies on degradation of OLEDs fabricated with Ir(ppy)2(dtb-bpy)PF6 [ppy = 2-phenylpyridine, dtb-bpy = 4,4'-di-tert-butyl 2,2'-bipyridine [3]. We have found that applying a thicker-than-usual metal electrode results in shorter turn-on times and higher light emission, though little improvement in lifetime. It appears that the degradation of these devices occurs by a different mechanism from that of the ruthenium-based devices and may involve local heating leading to chemical decomposition of the organic material.

Observation of recurring but often transient dark-colored substances in both the Ru(bpy)3(PF6)2 and Ir(ppy)2(dtb-bpy)PF6 systems, seen both in the solid state and in solution samples, may also be indicative of decomposition.
Electronic Structure at Tetratetracontane/Au(111) Interface
Authors: Kanai Kaname , Ouchi Yukio , Seki Kazuhiko
Published: April 2011

Modification of the quasi two-dimensional surface state on Au(111) surface with adsorption of n-alkane molecule, tetratetracontane: TTC was investigated by angle-resolved photoemission spectroscopy (ARUPS) and X-ray photoemission spectroscopy (XPS). From ARUPS the energy band structure of the surface state of Au(111) surface is found to be significantly affected by TTC adsorption. The modified surface potential on Au(111) surface by the adsorption confines the surface electrons into the quantum well newly established between TTC wide energy gap and sp band gap of the Au(111) surface increasing its localization nature. Clear chemical shift in C 1s core level was observed in XPS spectrum for TTC layer right at the interface and small back-donation from Au(111) surface to TTC unoccupied states is suspected. On the other hand, a large interface dipole layer about 0.72 eV was observed by TTC adsorption. From these results, Pauli repulsion effect is expected not to have dominant effect on such large dipole formation on TTC adsorption.
Improvement of Durability in Silicon Nitride Barrier Films for Flexible OLED Displays under High Temperature and High Humidity Conditions
Authors: Akedo Kunio , Miura Atsushi , Noda Koji , Fujikawa Hisayoshi
Published: April 2011

We have developed a new silicon nitride (SiNx) multilayer barrier film by a plasma-enhanced chemical vapor deposition (CVD) for a flexible organic light emitting diode (OLED), which consists of SiNx films in two different deposition conditions, that is, a transparent SiNx layer (tr-SiNx) deposited with NH3 gas and an ultra-thin SiNx layer (cap-SiNx) deposited without NH3 gas, which caps over the former layer. This barrier film is expected to exhibit high durability under high temperature and high humidity conditions even at high deposition rate over 100 nm / minute, because the transparent SiNx layer, that is easily oxidized under such conditions, is protected by the cap-SiNx layer and the interface between them, and also show good transparency, because the opaque cap-SiNx layer is enough thin to be almost transparent to visible light. Thus, the multi-layer SiNx barrier film indicates the specific features as a high barrier performance, high transparency, and high productivity, and makes it possible to apply flexible OLED displays to automobile use.
Large Area Carbon Nanotube Films
Authors: Konesky Gregory
Published: April 2011

Carbon nanotube films can be used in a wide range of applications, from fuel cells, storage batteries, and super-capacitors, electron field emitters for displays, x-ray and beam sources, heat sinks and heat spreaders, and chemically robust filtering membranes, to name a few. Present approaches to carbon nanotube film production rely on filtration of a suspension, but creating this suspension requires the use of toxic and hazardous reagents and lengthy processing times. We describe an approach of uniaxial die pressing that incorporates a sacrificial layer to prevent binding of the carbon nanotube film to the compression surfaces. Water, or other solvents, acts as a release agent. No binder is used. The process is scalable in terms of film thickness and area. Development of an extrusion process employing these principles is described.
Patterning Submicron Features on Flexible Plastic Substrates by Optical Lithography
Authors: Péter Mária , de Laat Wim , Giesen Peter T. M. , Gui Cheng-Qun , Meinders Erwin R.
Published: April 2011

Manufacturing transistors on thin flexible polymer foils is challenging and differs from standard Si processing due to the dimensional instability of the substrate influenced by moisture uptake, temperature and handling. A thorough analysis of material properties of the tested foil was performed to understand its behavior during lithography and subsequently to improve the processing. Imaging experiments on 100 µm polyethylene naphthalate (PEN) foils were performed with a PAS 5500/100D ASML step and repeat I-line (365 nm) system equipped with reticles having features of several microns and also sub-micrometer dimensions. A foil lamination process was developed to improve the dimensional stability during processing and to achieve a good surface flatness crucial for sub-micrometer imaging. The optimum process window for sub-micrometer critical dimensions was determined by performing a Focus Exposure Matrix (FEM) experiment in which the energy and focus were increased stepwise. The optimum imaging conditions were derived from SEM analysis. The results indicated a reproducible and good patterning accuracy for making patterns below 1µm size.
Environmental Passivation and Temperature Cycling of PCBM - Polymer Solar Cells
Authors: Anctil Annick , Merrill Andrew , Cress Cory , Landi Brian , Raffaelle Ryne
Published: April 2011

In the present work, polymer solar cells were fabricated from composite blends of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly(3-hexylthiophene)-(P3HT with PCBM[60] and PCBM[70]. The composite blends were used as active layers in an ITO/PEDOT:PSS/active layer/Al device structure. Power conversion efficiencies have been measured from current-voltage (I-V) measurements for each of these different composite blends under simulated AM1.5 illumination. In the case of the MEH-PPV devices, the I-V performance has been measured as a function of polymer molecular weight, type of fullerene derivative (C60 or C70), and PCBM:polymer ratios. The highest efficiencies for the ranges used in this study were obtained using the 150,000 g/mol MEH-PPV molecular weight, the C70 PCBM derivative, and a 1:4 MEH-PPV:PCBM ratio. The effect of thermal cycling on the I-V performance for both MEH-PPV and P3HT devices has also been measured from 77K to 330K. The devices exhibited a positive temperature coefficient for the short-circuit current density (Jsc), which dominated the overall efficiency of the device over this temperature range. Finally, the use of a combination of parylene and polymethylmethacralate for device passivation was shown to provide a dramatic reduction in device degradation under ambient conditions as compared to non-passivated devices.
Determination of Nanomaterial Energy Levels for Organic Photovoltaics by Cyclic Voltammetry
Authors: DiLeo Robert Ann , Anctil Annick , Landi Brian , Cress Cory , Raffaelle Ryne P
Published: April 2011

A wide variety of nanomaterials and associated nanomaterial/polymer composites are being developed in an effort to produce higher efficiency organic solar cells. This development requires a fundamental understanding of the energy levels for the individual materials, and their composites, to enable device designs which posess appropriate energy level matching. Cyclic voltammetry (CV) allows for the determination of the band gaps (Eg) and energy levels of these various nanomaterials and composites by measuring their oxidation and reduction potentials. These potentials correspond to a given material's ionization potential (IP) and electron affinity (EA), respectively. The results for the EA, IP, and Eg have been determined by CV for derivatized fullerenes and CdSe quantum dots (QD), measured in isolation, and in conjugated polymer composites with MEH-PPV. In addition, CV measurements conducted under dark and illuminated conditions were used to investigate the relationship between energy levels within the composites.