bluuebunny/crossref_metadata_2025_split huggingface dataset:
Versatile Metal Oxide Nanowire Devices Achieved via Controlled Doping
Authors: Dattoli Eric , Wan Qing , Lu Wei 
Published: April 2011

AbstractWe 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

AbstractThis 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

AbstractOne 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

AbstractCombined 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

AbstractWith 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

AbstractIt 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

AbstractPhotoluminescence (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

AbstractA 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

AbstractRecently, 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

AbstractIn 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

AbstractQuantitative 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

AbstractThe 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

AbstractGold 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

AbstractAl 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

AbstractMagnetic 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

AbstractThe 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

AbstractQualitative 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

AbstractThe 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

AbstractModification 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.