bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of Poly-SiGe Deposition Processes for Modular MEMS Integration
Authors: Lin Blake C.-Y. , King Tsu-Jae , Howe Roger T. 
Published: April 2011

ABSTRACTThis paper describes a bi-layer deposition technique to reduce the strain gradient of polycrystalline silicon-germanium (poly-SiGe) thin films without the use of any post-deposition annealing. By adjusting deposition conditions such as temperature, pressure, and/or flow rates of reactants, poly-SiGe films with required low average stresses can be obtained. Using the bi-layer technique, a strain gradient of 1.1×10-5 μm-1 (equivalent to 88 mm radius-of-curvature) has been achieved in 3.9 μm-thick poly-SiGe. This strain gradient would cause only 0.055 μm tip deflection for a 100 μm-long cantilever. The thermal budget was ∼10 hours at 425 °C, and no post-deposition annealing was required. The bi-layer film also exhibits low compressive average stress (-36 MPa) and low resistivity (0.55 mΩ-cm).
3D Small Angle X-Ray Scattering (SAXS) on deformed PVDF Foils
Authors: Maier Guenther , Wallner Gernot , Fratzl Peter 
Published: April 2011

ABSTRACT3D Small Angle X-ray scattering (3D – SAXS) was applied to study the microstructure and the deformation mechanism in PVDF – foils (polyvinyhdene fluoride). SAXS is a powerful tool to investigate structural changes in deformed polymers to reveal morphology at the nanometer scale. When PVDF is strained the structure changes from spherohtic isotropie to a highly anisotropie fiber bundle structure, which requires a full three-dimensional analysis of the SAXS signal.
Study of high aspect ratio etching in silicon by a mixture of SF6/O2 using a 2-D model based on a Monte Carlo approach.
Authors: Marcos G. , Rhallabi A. , Ranson P. 
Published: April 2011

ABSTRACTThe subject of this paper is to describe and comment on results from an etching model based on Monte Carlo method. It calculates the temporal profile evolution of the silicon substrate under an SF6/O2 plasma chemistry and a cryogenic process. This work was conducted in correlation with an experimental set-up to ensure the validity of the final results. Some in-situ measurements obtained in the gas phase allowed estimation of the incident kinetic parameters such as main ion and neutral fluxes. Collisionless sheath model is connected to the surface model to determine energetic and angular ion distribution functions. The study focuses on final properties of deep and thin trenches used in new power components. The development of a simulation tool appears as an useful mean to understand the role of certain parameters not easily controlled by the etching machine. In this article, results concerning the topography and defects usually met during such an etching process are shown and discussed.
Resist Poisoning-Free Advanced PECVD-Based Anti-Reflective Coating (ARC) for 90nm Technology and Beyond
Authors: Ahn Sang H. , Rathi Sudha , Liu Jean , Botelho Heraldo , Yeh Wendy , Seamons Martin , Witty Derek , M'Saad Hichem 
Published: April 2011

ABSTRACTA nitrogen-free (N-free) dielectric anti-reflective coating (DARC®) was cost-effectively developed in a plasma-enhanced chemical vapor deposition (PECVD) reactor to eliminate the 193nm resist poisoning interaction caused when N2O is used as a precursor [1]. Although it was found that even a N-free ARC could poison sensitive 193nm resists with –OH radicals [2], which either exist inherently in the ARC or result from H2O absorption by the ARC surface, the current investigation has revealed that it was possible to minimize resist poisoning. Our investigation showed that compressive film stress directly correlates to H2O resistance. Therefore, it was possible to greatly improve the ARC resistance to H2O absorption by creating and maintaining a process regime that makes the ARC film dense. The dense ARC film demonstrated promising lithography performance with minimal resist poisoning as well as excellent shelf life and O2-ashing resistance. This paper explores the N-free DARC material, its development, lithographic integration results and implementation in a production environment to eliminate 193nm resist poisoning.
Structure Evolution and Corresponding Electrical Properties in Weakly Bound Co-C60 Mixture
Authors: Sakai Seiji , Naramoto Hiroshi , Xu Yonghua , Priyanto Tri Hardi , Lavrentiev Vasily , Narumi Kazumasa 
Published: April 2011

ABSTRACTMixture films of Co and C60 with various compositions were fabricated by co-evaporation under UHV condition. As for the saturation composition with C60-based phase, Co5C60 is deduced from the systematic Raman analysis. It is reasonably interpreted that the C60-based phase can be realized by less than one electron transfer per a Co atom into C60 and the contribution of a covalent bonding which induces a differently coordinated structure of the C60 molecules from the fcc-C60. The electrical conduction features are dependent on the Co content. In the C60-based phase up to Co5C60, the conduction mechanism seems to be described by the band concept modified with the disorder, followed by the hopping conduction through the precipitated Co clusters or particles and then, by the metallic one with increasing Co content.
Phase Characterization and Morphology Control of Electrospun Nanofibers of Pani/Pmma Blends
Authors: Desai K. , Sung C. 
Published: April 2011

ABSTRACTElectrospinning derived from electro spraying is a process by which sub-micron polymer fibers can be produced using an electrostatically driven jet of polymer solution. The fibers are collected as non-woven mat and offer a high surface to volume ratio. Polyaniline is an organic conducting polymer and can be used to fabricate conducting nano fibers by blending with suitable polymers like poly methyl methacrylate. In this present work we have explored the effects of electrospinning parameters on the formation of PANI/PMMA fibers and the phase morphology of the electrospun fibers using advanced electron microscopy and scanning probe microscopy techniques.
Self assembled gold and silver nanoparticulates on silicon nanotips as surface enhanced Raman active substrates
Authors: Chattopadhyay S. , Lo H. C. , Chen K. H. , Hsu C. H. , Chen L. C. 
Published: April 2011

AbstractSilicon nanotips, grown via electron cyclotron resonance plasma chemical vapour deposition, with apex diameters of ∼2nm and lengths of 1000 nm and densities of 1011/cm2 were used as a new substrate for surface enhanced Raman spectroscopy. Ion beam sputtered gold and silver self assemble on these substrates as nanoparticulates of 4–10 nm diameter and these metallic nanoparticulates assist in the surface enhancement of Raman signals of analytes. Molecules such as Rhodamine 6G and bis-Pyridyl ethylene of varied concentrations, in the range of 10-6-10-10 M, has been studied on these substrates and enhancements in the range of 106-108 were observed.
Growth of Carbon Nanotubes Using Uniformly Distributed Cobalt Nanoparticles as Catalyst: Controlled Growth and Structural Characterization
Authors: Huh Yoon , Lee Jeong Yong , Choi Sang Kyu , Lee Cheol Jin 
Published: April 2011

ABSTRACTWe have controllably grown carbon nanotubes using uniformly distributed cobalt nanoparticles as catalyst. Cobalt nanoparticles with a uniform size were synthesized by chemical reaction and colloidal solutions including the cobalt nanoparticles were prepared. The cobalt nanoparticles were uniformly distributed on silicon substrates by a spin-coating method. Carbon nanotubes with a uniform diameter were synthesized on the cobalt nanoparticles by thermal chemical vapor deposition of acetylene gas. The density and vertical alignment of carbon nanotubes could be controlled by adjusting the density of Co nanoparticles.
Incorporation of Functional Metal Oxide Materials in Chemical Microsystems
Authors: Yao Nan , Yeung King Lun 
Published: April 2011

ABSTRACTTiO2-SiO2 aerogel with various TiO2 contents was successfully deposited into a microchannel. SEM, XPS and liquid-phase photocatalytic oxidation reaction of phenol were used to examine the TiO2-SiO2 aerogel's microstructure and reactivity. The TiO2 content has a significant effect on the aerogel network and its adhesion on the microchannel. High open and cross-linking or ordered macroporous structure can be formed in TiO2-SiO2 aerogels with lower TiO2 content (5wt% or 10wt%). The conversion of phenol is around 36.6% during the reaction when this aerogel incorporated microchannel is used as microreactor.
Nanocrystalline Mixed Metal Oxides – Novel Oxygen Storage Materials
Authors: Sarkas Harry , Murray Patrick G. , Fay Aaron , Brotzman R. W. 
Published: April 2011

ABSTRACTNanophase Technologies Corporation (NTC) employs a new physical vapor synthesis technique to manufacture ceria-based mixed rare earth oxide nanomaterials. The mixed rare earth oxide nanoparticles are nonporous, dense, discrete crystals. The compositions are solid solutions that remain thermally stable to above 1050°C.Ceria is an active oxygen storage material. Doping ceria with other rare earth metals enhances the thermal stability of nanocrystalline particle size and increases the oxygen storage capacity (OSC). The mean particle size and OSC of ceria-based mixed rare earth oxides are presented as a function of particle composition, morphology, and thermal history.These materials are commercially available and are being engineered for several applications including oxygen storage catalysts and polishing materials.
The Use of Mesoporous Systems for Preparation of One-Dimensional Ordered Magnetic Nanowires
Authors: Eliseev Andrei A. , Napolskii Kirill S. , Gorozhankin Dmitry F. , Lukashin Alexei V. , Tretyakov Yuri D. , Grigorieva Natalia A. , Grigoriev Sergei V. , Vorobieva A. A. , Görnert Peter 
Published: April 2011

ABSTRACTHere we report the synthesis and investigation of iron and iron oxide nanowire arrays using mesoporous silica as a host material. In the present work a novel variant of synthesis of ordered magnetic nanowires in the mesoporous silica matrix was suggested. The method is based on the incorporation of a hydrophobic metal compound into the hydrophobic part of silica-surfactant composite. The amount of iron intercalated into the mesoporous matrix was measured by chemical analysis. In all samples it corresponds well to with the molar ratio SiO2: Fe = 9:1. To provide crystallinity of nanowires additional thermal treatment was performed. Thus prepared nanocomposites were characterized by TEM, ED, SAXS, SANS, BET and magnetic measurements. The anisotropy parameters of nanowires were determined using two non-correlated methods: temperature dependence of magnetic susceptibility and small angle polarized neutron scattering. It was found that the particle length increases with the increasing of the decomposition temperature of the metal complex. Obviously it deals with crystallization and growth of metal particles inside the pores at a constant diameter of a single particle. For iron containing sample annealed at 375 °C (form factor of nanowire is about 40), the coercive force at room temperature was found to be 145 Oe at saturation magnetization of 1.2 emu/g, which is not far from modern information storage. It was shown that particles shape and size are in good agreement with that of the pores. Particles are uniform and well ordered in the silica matrix. Thus, the suggested method leads to one-dimensional anisotropic nanostructures which could find an application as high-density data storage magnetic media.
Carbon-Based Nanocomposite Materials For Cold Cathode Sources
Authors: Karabutov Alexander V. , Ralchenko Viktor G. , Gordeev Sergey K. 
Published: April 2011

ABSTRACTTo find an alternative for CVD diamond films and carbon nanotubes for low-field electron emission sources and cold cathode applications, we have designed a novel class of nanomaterials with excellent field emission properties – dielectric/carbon nanocomposites, in which different insulating nanoparticles such as silicon oxide, boron nitride in cubic and hexagonal forms, and nanodiamond were used inside a pyrocarbon matrix. The thickness of pyrocarbon shells covering the dielectric particles can be controlled in a wide range during the CVD process. The best samples of the nanocomposites with all four kinds of dielectric material show excellent field emission properties with threshold fields of as low as 0.5–1 V/μm, good surface uniformity and long-term stability. An effect of post-growth treatment with oxygen and hydrogen plasma on the emission was also studied. A mechanism of the emission is discussed basing on quantum properties of nanostructured thin (two-dimensional) carbon covering the dielectric particles. The mechanism could be suitable for wide range of nanostructured sp2-bonded carbon objects.
Synthesis of Ultrafine Oxide Powders by Hydrothermal-Ultrasonic Method
Authors: Meskin Pavel E. , Kolenko Yury V. , Baranchikov Alexander E. , Ivanov Vladimir K. , Churagulov Bulat R. , Oleynikov Nikolay N. 
Published: April 2011

ABSTRACTIn the present work, a novel method of synthesis has been developed to obtain highly dispersed oxide powders. This method is based on the combination of hydrothermal and ultrasonic treatment and uses the effect of acoustic cavitation.Hydrothermal-ultrasonic treatment was carried out under the following conditions: T= 423 - 523 K, t = 10 min. -3 h. and ultrasonic frequency ν = 21.5 kHz. The control experiments (without ultrasound) were performed under the same conditions. The products were characterized by X-ray diffraction (XRD), thermal analysis (TGA), transmission electron microscopy (TEM). The specific surface area was determined by the BET method.It was found that high-temperature hydrolysis of cobalt (II) nitrate in ultrasonic field results in formation of considerably smaller particles of Co3O4 in comparison with conventional high-temperatures hydrolysis (mean particle size decreases from 600–650 nm to 60–70 nm). It must be noted that Co3O4 samples obtained by hydrothermal-ultrasonic treatment possess mesoporous structure.Ultrasonic-hydrothermal processing of amorphous gels of zirconyl and titanyl hydroxides leads to significant raise of the rate of crystallization process and formation of nanopowders of zirconia and titania (mean particle size 7–16 nm).It must be pointed that the use of ultrasonic treatment during hydrothermal processing of amorphous gel of zirconyl hydroxide and 0.3 M aqueous solution of H2TiO(C2O4)2 leads to increase of the content of thermodynamically stable phases in the products of synthesis.
Dynamics of water, hydrated-ions and charged polymers in highly-confined films, and their role in friction modification
Authors: Klein Jacob , Raviv Uri , Perkin Susan , Kampf Nir , Giasson Suzanne 
Published: April 2011

ABSTRACTRecent studies have revealed that, in contrast to non-associating liquids such as oils or organic solvents, salt-free water retains a viscosity close to its bulk value even when confined to films thinner than some 3 nm, indeed down to only one or two monolayers thick [1,2]. For the case of high concentration aqueous salt solution compressed down to subnanometer films between charged surfaces, the trapped hydrated ions serve to act as molecular ball-bearings, sustaining a large load while remaining very fluid under shear [3]. This behaviour is attributed to the tenacity of the hydration sheaths together with their rapid relaxation time. Finally, a very recent study [4] has shown that when charged polymer brushes in aqueous media are compressed and slid past each other, they provide a lubrication that is considerably superior to that afforded by neutral brushes: This is attributed on the one hand to the resistance to mutual interpenetration of the chains due to entropic barriers in the good-solvent conditions, and, on the other hand, to the hydration-sheaths on the charged polymer segments which can act – as noted above – as molecular ball-bearings.
Detection of Interfacial Structures of Poly(ethylene glycol), Poly(propylene glycol) and Their Copolymers at Liquid/Solid Interfaces Using Sum Frequency Generation Vibrational Spectroscopy
Authors: Chen Chunyan , Wang Jie , Even Mark A. , Chen Zhan 
Published: April 2011

ABSTRACTWe have applied sum frequency generation (SFG) vibrational spectroscopy, a submonolayer surface sensitive analytical technique, to study interfacial structures of poly (ethylene glycol) (PEG), poly (propylene glycol) (PPG), their solutions, their copolymers, and copolymer solutions while contacting different media including air, fused silica, and various polymers.For the first time, conformations of polyether materials at various interfaces have been shown at the molecular level in situ. Depending on the hydrophobicity of the solid contacting media, the liquid polymers PEG and PPG show different conformations at different interfaces, which can be correlated to molecular interactions at these interfaces. The favorable interaction between hydrophobic media and the hydrophobic segments, methylene or methyl groups, of polyethers causes an ordered conformation with these groups standing up at the interface. The unfavorable interaction between hydrophilic media and hydrophobic segments of the polyethers induces interfacial methylene or methyl groups to have a random structure or to lie down at the interfaces, indicated by the weakening or even absence of SFG signals. For comparison, interfaces between aqueous PEG or PPG solutions and air, polystyrene (PS), poly(methyl methacrylate) (PMMA), and fused silica have also been investigated. In addition, we have studied conformations of pluronics at various interfaces, showing that different blocks have different interface activities. The interfaces are always dominated by the PPG segments. The studies on molecular level interfacial structures of PEG, PPG and pluronics will help us to understand and control the interfacial behavior of liquids at interfaces.
Segmental Dynamics of polymers in 1 and 2nm slit-pores
Authors: Kuppa V. , Manias E. 
Published: April 2011

ABSTRACTMolecular dynamics computer simulations are used to study the structure and dynamics of 1nm wide films of poly(ethylene oxide)(PEO) confined between mica type layered silicates of different cation exchange capacities(CEC). The simulation setup mimics the experimental systems formed by intercalation of PEO in silicate clays with differing numbers of inherent charges. Counterbalancing lithium cations are present in the interlayer gallery to offset the negative charge on the silicate platelets created by the isomorphic substitution of trivalent aluminum by divalent magnesium ions. It is seen that the presence of the lithium has a significance influence on the behavior of the system, with PEO segmental motion strongly dependent on the number of Li+ present in the slit pore. In particular, the coexistence of fast and slow modes for C-H bond dynamics is heavily affected due to the strong interaction between the Li+ ions and partially charged PEO oxygen. In conjunction with local density inhomogeneities, the coordination between lithium and oxygen is responsible for the anomalous segmental dynamics of nanoconfined PEO.
Intercalated Polymer Nanocomposites Prepared in Supercritical Carbon Dioxide.
Authors: Garcia-Leiner Manuel , Lesser Alan J. 
Published: April 2011

ABSTRACTAn alternative route to prepare polymer-clay nanocomposites using supercritical carbon dioxide (scCO2) is described. The presence of clay nanoparticles significantly influences the morphology, foaming process and crystallization of a polymer when processed in scCO2. Intercalated structures are successfully produced in the presence of scCO2 even when favorable interactions between the polymer and the clay are not present. The effect of scCO2 on the intercalation process is analyzed for a variety of polymer systems both with modified and unmodified clays. By controlling the hydrophilicity of the polymer and clay systems, specific understanding of the effect of scCO2 on the structure and morphology of the nanocomposites is obtained. Experimental results show significant increases in the clays d-spacings for scCO2-treated samples. This behavior is consistent regardless of the nature of the polymer, showing significant amounts of intercalation even in purely hydrophobic polymers.
Modeling of Deformation in Nanocrystalline Copper Using An Atomistic-Based Continuum Approach
Authors: Warner D. H. , Sansoz F. , Molinari J. F. 
Published: April 2011

ABSTRACTThe deformation of copper with grain size less than 10 nm is investigated using a 2D continuum model incorporating atomistically-based constitutive relations. The local constitutive response of a series of symmetric and asymmetric tilt grain boundaries is obtained using an atomistic quasicontinuum method under tension and shear. The atomistic results show that it is possible to associate a constant maximum stress with each deformation mechanism triggered in the GB vicinity, i.e. GB sliding and decohesion, atom shuffling and partial dislocation emission. The GB strength is always found weaker in shear than in tension. This information is incorporated into a continuum polycrystalline model tested under compression. This model provides useful insights, in the absence of intragranular plasticity, into the onset of macroscopic quasi-plasticity, which results from GB sliding and collective grain rotation mechanisms.
TEM Investigation on Microstructural Characteristics in Nanostructured Al-Mg Alloy
Authors: Park Young S. , Chung Kyung H. , Kim Nack J. , Lavernia Enrique J. 
Published: April 2011

ABSTRACTThe microstructural evolution in a nanostructured Al-Mg alloy fabricated by cryogenic mechanical alloying (cryomilling), was investigated using transmission electron microscopy (TEM). Nanostructured Al-Mg powders were first synthesized by a mechanical alloying under liquid nitrogen media (cryomilling), and the powders were subsequently degassed, hot isostatically pressed, and extruded into a full dense, bulk form. The results showed that Si containing phases and (Fe,Ni)Al intermetallics existed in as-extruded Al-Mg alloy. In addition, the extrusion temperature has a strong influence on the formation of microstructural anisotropy. A lower extrusion temperature yields a microstructure that is more anisotropic relative to that present at the higher extrusion temperature. More specifically, at the lower temperature, the nano-sized Al grains have a tendency to rotate towards the <111> direction, along the extrusion direction.
Creep Resistance of the Directionally Solidified Ceramic Eutectic of Al2O3/c-ZrO2(Y2O3)
Authors: Yi Jin , Argon Ali S. , Sayir Ali 
Published: April 2011

ABSTRACTThe creep resistance of the directionally solidified ceramic eutectic of Al2O3/c-ZrO2(Y2O3) was studied in the temperature range of 1200–1520°C both experimentally and by mechanistic dislocation models. The creep of the eutectic in its growth direction exhibits an initial transient that is attributed to stress relaxation in the c-ZrO2(Y2O3) phase, but otherwise in steady state shows many of the same characteristics of creep in sapphire single crystals with c-axis orientation. The creep strain rate of the eutectic has stress exponents in the range of 4.5–5.0 and a temperature dependence suggesting a rate mechanism governed by oxygen ion diffusion in the Al2O3. A detailed dislocation model of the creep rate indicates that much of the nano-scale encapsulated c-ZrO2(Y2O3) is too small to deform by creep so that the major contribution to the recorded creep strain is derived from the diffusion-controlled climb of pyramidal edge dislocations in the Al2O3 phase. The evidence suggests that the climbing dislocations in Al2O3 must repeatly circumvent the c-ZrO2(Y2O3) domains acting as dispersoids resulting in the stress exponents larger than 3. The creep model is in very good agreement with the experiments.