bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nano-scale Characterization of Surface Defects on CMP-finished Si Wafers by Scanning Probe Microscopy Combined with Laser Light Scattering
Authors: Arima Kenta , Shigetoshi Takushi , Inoue Haruyuki , Kawashima Tsukasa , Hirokane Takaaki , Kataoka Toshihiko , Morita Mizuho 
Published: April 2011

ABSTRACTScanning probe microscopy has been widely used to evaluate surface microroughness on Si wafers after chemical mechanical polishing (CMP) processes. In this article, we utilize atomic force microscopy (AFM) combined with laser light scattering to detect nano-scale surface defects called microscratches on CMP-finished Si wafers. We find that most microscratches detected by the combined method are very shallow trenches with widths and depths of 80–200 nm and 0.1–0.2 nm, respectively. The dependence of scattered-light intensity on the size of microscratches agrees with theoretical calculations within one order of magnitude.
Shallow Junction Engineering by Phosphorus and Carbon Co-implantation: Optimization of Carbon Dose and Energy
Authors: Cagnat Nathalie , Laviron Cyrille , Mathiot Daniel , Rando Chris , Juhel Marc 
Published: April 2011

AbstractCarbon co-implantation after pre-amorphization implantation (PAI) has been studied for Boron shallow implants and can be also used to reduce Phosphorus diffusion. The expected role of Carbon is to trap Si interstitials responsible of Phosphorus diffusion. A known drawback of this kind of co-implantation is junction leakage caused by Carbon deep levels. To find a compromise between diffusion reduction and leakages, it is necessary to optimize the location and the amount of Carbon with respect to Si interstitials.In this work, we present full sheet experiments optimizing Carbon implanted energy and dose in order to minimize Phosphorus diffusion. First, we performed a PAI with Germanium. Then Carbon was implanted at several energies and doses to locate its projected range (Rp) at various locations with respect to the Phosphorus peak and the amorphous/crystalline interface. Finally the Phosphorus implant was placed completely within the amorphized area. Dopants were activated by a spike anneal at 1080°C, 1055°C or 1000°C. SIMS analysis and Rs measurements were used to understand Carbon action on Phosphorus diffusion and activation. The role of C in suppressing P diffusion is discussed in regards of the specificities of P diffusion mechanism.
Surface Engineering in Microfluidic Devices for the Isolation of Smooth Muscle Cells and Endothelial Cells
Authors: Murthy Shashi , Plouffe Brian , Radisic Milica 
Published: April 2011

AbstractMicrofluidic cell separation systems have emerged as attractive alternatives to traditional techniques in recent years. These systems offer the advantages of being able to handle small sample volumes and at the same time achieve highly selective separation. Conventional separation techniques, including both fluorescence-activated cell sorting (FACS) and magnetic-activated cell sorting (MACS), typically require a pre-processing incubation step to attach ligated tags (such as fluorescent dyes or magnetic beads) to cell surfaces prior to separation. These techniques are also constrained by infrastructure and high cost. Microfluidic devices with surface-immobilized adhesion molecules eliminate the need for pre-processing incubation and are a low cost alternative.We describe the selective adhesion of smooth muscle cells and endothelial cells in microfluidic devices coated with adhesion peptides. The device geometry is such that the shear stress varies linearly as a function of flow channel length, allowing simultaneous evaluation of the effects of surface chemistry and fluid shear on cell adhesion. The adhesion peptides, val-ala-pro-gly (VAPG) and arg-glu-asp-val (REDV), are known to bind selectively to smooth muscle cells and endothelial cells, respectively. These peptides were tethered to the device surface using silane chemistry and NHS-ester coupling. Cell adhesion was examined in a shear stress range of 1.3-4.0 dyn/cm2. Under these conditions, endothelial cells show significantly higher adhesion to REDV-coated devices compared to smooth muscle cells and fibroblasts. Correspondingly, smooth muscle cell adhesion in VAPG-coated devices is much greater than that of endothelial cells and fibroblasts. This selective binding behavior is also observed when mixed suspensions of the three cell types are flowed into both types of peptide-coated microfluidic devices. These results suggest that microfluidic devices coated with REDV and VAPG can be used as effective separation tools in various applications, such as tissue engineering. Specific examples of applications in cardiac and skin tissue engineering will be discussed.
Polymerization Kinetics of Methacrylic Groups in Organic-Inorganic Hybrid Polymeric Thin Films
Authors: Zha Congji , Luo Xinshi , Luther-Davies Barry 
Published: April 2011

ABSTRACTIn this paper, the polymerization kinetics of unsaturated double bonds (C=C) in TiO2- and ZrO2-doped hybrid polymeric thin films during UV irradiation and thermal curing is studied by monitoring the variation of C=C absorption band at 1630 cm-1 using FT-IR spectroscopic technique. Experimental results showed that polymerization of the unsaturated C=C groups in the TiO2- and ZrO2-doped hybrid polymers can be realized by either photo-irradiation or thermal treatment. The UV-induced polymerization process is much faster than thermal curing, but a full conversion of C=C groups into polyacrylate chains cannot be achieved without thermal treatment. The catalytic effect of TiO2 and ZrO2 on promoting the polymerization of C=C groups was observed, and the time of UV exposure and thermal curing for cross-linking C=C bonds was found to decrease with the increase of the concentration of TiO2 and ZrO2. The activation energy of the hybrid material containing varied concentration of TiO2 and ZrO2 was calculated, and the results indicated that TiO2 is more active than ZrO2 in promoting the polymerization of the unsaturated C=C bonds. Finally, the mechanisms for TiO2 and ZrO2 enhancing the material's photosensitivity (i.e. promoting polymerization of C=C bonds) have been proposed and discussed.
Controlled silica deposition on soft-lithography fabricated poly-L-lysine templates
Authors: Butler Randall , Ferrell Nicholas , Naik Rajesh R. , Hansford Derek J. 
Published: April 2011

AbstractWe describe the combination of soft-lithographic patterning and biomolecule-induced deposition to create microscale patterns of silica on a diverse array of substrates. A soft lithographic technique was used to create a sacrificial layer of the polymer poly(n-propyl methacrylate) (PPMA) on the desired substrate. Subsequently, poly-L-lysine was deposited on the substrate, after which removal of the PPMA yielded a pattern of PLL on the substrate. Exposure of the PLL template to a silicic acid solution resulted in silica deposition in the pattern spatially and geometrically controlled by the PLL. With this procedure, we have created both continuous and discontinuous silica patterns on metallic, ceramic, and polymer substrates. While morphology of the deposited silica varied between substrates, the ability to pattern silica through this templated growth was demonstrated on all investigated substrates. EDS, optical micrography, and SEM analysis verified the controlled deposition of silica on the PLL template patterns. This PLL template-mediated induction of silica formation may facilitate the incorporation of silica in new microdevices and serve as a prototype process for controlled deposition with other biomolecule-material systems.
Visible-Range Luminescence Study in Indium Oxide Nanowires
Authors: Calestani Davide , Zha Mingzheng , Mazzera Margherita , Lazzarini Laura , Zappettini Andrea , Salviati Giancarlo , Paorici Carlo , Zanotti Lucio 
Published: April 2011

AbstractThe interest in semiconducting metal oxide nanowires for gas sensing devices is today very high. Besides common materials such as SnO2 or ZnO, also In2O3 has been obtained in this quasi-1D morphology . In the present work In2O3 nanowires have been grown by vapor transport process starting from 6N pure In. For a better knowledge of the fundamental properties and the sensing mechanism of In2O3 nanowires, the obtained samples have been investigated by different techniques, focusing mainly on the optical characterization. Their morphology and structure have been studied by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray diffraction. The optical properties have been investigated as well, mainly by means of photo- (PL) and Cathodo-luminescence (CL) both applied in the UV-Visible range. A complex emission spectrum has been revealed and assigned to specific defects thanks to a deep analysis of the bands as functions of temperature (varying from 20 to 300K) and to suitable thermal treatments (in oxygen rich atmosphere at 1000°C). Moreover, the effects of electron beam irradiation have been pointed out by performing CL spectra on a single In2O3 nanowire after different irradiation times. The possible influence of the substrate has been verified by measuring low temperature spectra on In2O3 nanowires grown both on alumina and silicon substrates.
Novel Approach for Fabricating Highly Ordered Colloidal Crystals using Fluorinated Solvent
Authors: Takeda Satoshi , Wiltzius Pierre 
Published: April 2011

AbstractA novel technique for fabricating highly ordered colloidal photonic crystals has been developed. In this method, a droplet of water containing polystyrene microspheres was added to the surface of a fluorinated solvent bath. Consequently, the two liquids remained separated and the colloidal particles self-assembled into close-packed structures at the interface between them. By transferring the droplet onto a glass slide, a highly ordered crystal was obtained. This technique offers a new, potentially easier, and more effective approach than currently used. We believe that it will open new ways for fabricating materials based on colloidal crystals as well as applying the colloidal photonic crystals to optical devices.
Single-Walled Carbon Nanotube Scaffolds Promote Stem Cell Differentiation into Bone Forming Cells
Authors: Tu Xiaomin , Skinner Charles M , Chen Xiao-Dong , Zhao Wei 
Published: April 2011

AbstractThe use of carbon nanotubes for tissue engineering has become one of the most fascinating applications. The exquisite electronic and mechanical properties of carbon nanotubes may provide a three-dimensional (3D) microenvironment that closely mimics in vivo situation for facilitating the use of stem cells in the tissue regeneration. Therefore, it is important to know whether carbon nanotubes enhance the adhesion, proliferation, and differentiation of stem cells. Here, we hypothesized that the carbon nanotubes promote the differentiation of osteoblast progenitors into mature osteoblasts. To test this hypothesis, we quantified the differentiation of murine osteoblast progenitors, with and without pro-differentiating growth factor Bone Morphogenetic Protein-2 (BMP-2), cultured on the 3D scaffolds made by single-walled carbon nanotubes (SWNTs). Three types of SWNT samples, chitosan functionalized SWNTs, acid-oxidized SWNTs, and surfactant-free pristine SWNTs were used for the construction of these 3D microarchitectures. Osteoblast progenitors were harvested from calvariae from 3∼5-day-old mice, and cultured on the 3D scaffolds made by carbon nanotubes until ∼ 80% confluent. Then the cells were treated with BMP-2 (100 ng/ml) for 5 days. It was found that osteoblast progenitors cultured on the SWNTs dramatically increased the level of mature osteoblastic marker osteocalcin in either the absence or the presence of BMP-2, as compared to the cells cultured on the regulate tissue culture plastic plates. The results suggested that SWNTs highly promote osteoblast progenitor differentiation into mature osteoblasts. The finding indicates that SWNTs may provide an ideal scaffold for facilitating the differentiation of osteoblast progenitors in the repair of bone defects.
Si Whisker Growth by Hydrogen Radical using Hot Filament CVD Reactor
Authors: Nagayoshi Hiroshi , Nishimura Suzuka , Terashima Kazutaka , Matsumoto Nobuo , Ulyashin Alexander G. 
Published: April 2011

AbstractThis paper describes the growth mechanism of silicon whisker on a silicon substrate using hot filament CVD reactor. Only hydrogen is used as source gas. The particle layer could be obtained at high filament current condition under hydrogen ambient. XPS analysis result suggests that the particle is composed of tungsten silicide. The deposition condition of the particle layer is much depended on the substrate size, surface condition and the distance between the substrate and the filament. The experimental results suggest that the silicon hydride, which generated at the silicon surface by hydrogen radical etching, react with the tungsten filament material around the filament, depositing on the silicon substrate. The silicon surface is etched by hydrogen radical and its resultant surface morphology is much depended on the particle deposition pattern. Many silicon whiskers, which diameter is varied from 10 to 50 nm, are observed on the textured silicon surface when the residence time of the source gas in the reactor is long. Each whisker has a silicon particle on their tip. The silicon hydride generated by the hydrogen radical etching is much absorbed to the silicide particle when the source gas residence time is long, enabling the silicon whisker growth from the particle. The results suggest that nm size whisker structure is much stable compare to the bulk silicon against etching reaction.
Silicon Nanowire Electromechanical Switch for Logic Device Application
Authors: Li Qiliang , Koo Sang-Mo , Edelstein Monica D. , Suehle John S. , Richter Curt A. 
Published: April 2011

AbstractIn this paper, we have reported the fabrication and characterization of nanowire electromechanical switches consisting of chemical-vapor-deposition grown silicon nanowires suspended over metal electrodes. The devices operate as transistors with the suspended part of the nanowire bent to touch metal electrode via electromechanical force by applying voltage. The reversible switching, large on/off current ratio, small subthreshold slope and low switching energy compared to current CMOSFET make the switches very attractive for logic device application. In addition, we have developed a physical model to investigate the switching characteristics and extract the material properties.
Spatially Resolved Characterization of Plastic Deformation Induced by Focused-Ion Beam Processing in Structured InGaN/GaN Layers
Authors: Barabash R. , Ice G. , Kroger R. , Lohmeyer H. , Sebald K. , Gutowski J. , Bottcher T. , Hommel D. , Liu W. , Chung J.-S. 
Published: April 2011

AbstractIn this study the results of polychromatic X-ray microbeam analysis (PXM) of the structural changes caused by FIB in nitride heterostructures are presented and discussed in connection with micro-photoluminescence (μ-PL), fluorescent analysis, scanning electron (SEM) and transmission electron microscopy (TEM) data. It is shown that FIB processing distorts the lattice in the InGaN/GaN layer not only in the immediate vicinity of the processed area but also in the surroundings. A narrow amorphidized top layer is formed in the direct ion beam impact area.
Dynamics of Ion Beam Stimulated Surface Mass Transport to Nanopores
Authors: Hoogerheide David P. , Golovchenko Jene A. 
Published: April 2011

AbstractWe explore the ion beam-induced dynamics of the formation of large features at the edges of nanopores in freestanding silicon nitride membranes. The shape and size of these “nanovolcanoes”, together with the rate at which the nanopores open or close, are shown to be strongly influenced by sample temperature. Volcano formation and pore closing slow and stop at low temperatures and saturate at high temperatures. Nanopore volcano size and closing rates are dependent on initial pore size. We discuss both surface diffusion and viscous flow models in the context of these observed phenomena.
MeV Ion Beam Fabrication of Nanopores
Authors: Minamisawa Renato Amaral , Zimmerman Robert Lee , Muntele Claudiu , ILA Daryush 
Published: April 2011

AbstractWe have used MeV ion beams to fabricate nanopores in Poly(tetrafluorethylene-co-perfluoro-(propyl vinyl ether)) (PFA) fluoropolymer membranes. We have developed an in house system to produce nanopores. Using MeV ion beams we developed a method to produce pores from nanometers to one-micron diameter. A thin film of the PFA polymer was mounted to cover a window to a gas filled chamber and then exposed to a uniformly scanned MeV ion beam masked to define the exposed area. The gas leak rate through the fabricated pores was monitored by an in situ RGA system both during and after each bombardment to correlate the leakage with the total area of the pores produced. In this project we used MeV light and heavy ions to best define the pore diameter through each hole and the pore entrance and exit dimensions in the membranes.
Fluence Dependence of Thermoelectric Properties Induced By Ion Bombardment of Zn4Sb3 and CeFe2Co2Sb12 thin films
Authors: Smith C.C. , Budak S. , Guner S. , Muntele C. , Minamisawa R. A. , Zimmerman R. L. , ILA D. 
Published: April 2011

AbstractThermoelectric power generation is a promising technology for increasing the efficiency of electrical and optical electrical devices. We prepared samples by Electron Beam evaporating Zn4Sb3 and CeFe2Co2Sb12 thin films on silicon dioxide (silica) substrates. The materials were co-evaporated and then were prepared for gold over-coating. Following electron deposition we performed post ion bombardment at a constant energy of 5 MeV while varying fluence from 1×1012, 1×1013, 1×1014, 1×1015 ions/cm2, respectfully. The production of nano-clusters generated from the MeV Si ions bombardment modifies the electrical and phonon interactions in the materials. Also, we will report on the fluence dependence of the figure of merit, Seebeck Coefficient, thermal conductivity and electrical conductivity. In addition, Rutherford backscattering spectrometry (RBS) was used to analyze the elemental composition and the thickness of the deposited material.
Sudden Olivine LiFePO4 Nanocrystallisation by Progressive Introduction of Li into Ferrous Phosphate Structure
Authors: Sundarayya Y. , Kumaraswamy K.C. , Sunandana C. S. 
Published: April 2011

AbstractHomogeneous sub-micron sized particles of surface carbon coated phase pure LiFePO4 are synthesized by a novel non-aqueous oxalate-based sol-gel route. X-ray diffractogram of LiFePO4 reveals nanocrystals with average crystallite size 32(7) nm. The very large QS (nearly five times greater than that of Fe3+) value observed from Mossbauer spectrum is due to high spin configuration of 3d electrons and the asymmetric local environment at Fe site in LiFePO4. A uniform particle size distribution with grain size 100 - 150nm was observed in SEM with few irregular growths. Our synthetic route successfully overcomes the incidence of Fe3+, effectively controls undesirable particle growth and has the potential for upscaling and application as Li-ion battery cathodes. Progressive evolution of olivine structure by the interlock of FeO6 octahedra and PO4 tetrahedra with Li concentration is studied by introducing lithium in to LixFePO4 (0.0 × 1.0 ). A fairly abrupt phase transformation from monoclinic Fe3(PO4)2 to orthorhombic LiFePO4 shows up for x∼0.2 accompanied by structural disorder which gets stabilized at x 0.35. A systematic study of X-ray diffractograms shows nanocrystal nucleation and growth from an unstable low symmetry crystalline phase with considerable disorder.
Electronic Structure Investigation of MAX-Phases by Soft X-ray Emission Spectroscopy
Authors: Magnuson Martin 
Published: April 2011

AbstractThe electronic structure of nanolaminate Ti2AlC and Ti2AlN thin films, so-called MAX-phases, were investigated by soft X-ray emission spectroscopy. These nanolaminated carbide and nitride compounds represent a class of layered materials with a combination of properties from both metals and ceramics. The bulk-sensitive soft X-ray emission technique is particularly useful for detecting detailed electronic structure information about internal monolayers and interfaces. The Ti-Al bonding is manifested by a pronounced peak in the Ti L-emission of Ti2AlC and Ti2AlN that is not present in the binary TiC system. The spectral shape of Al L-emission in the MAX-phase is strongly modified in comparison to metallic Al. By replacing or partly exchanging C with N, a change of the electron population can be achieved causing a change of covalent bonding between the laminated layers, which enables control of the material properties.
Diffraction Microscopy using 20-kV Electron Beam for Multi-Wall Carbon Nanotubes
Authors: Kamimura Osamu , Kawahara Kota , Doi Takahisa , Dobashi Takashi , Abe Takashi , Gohara Kazutoshi 
Published: April 2011

AbstractDiffraction microscopy (or diffractive imaging) with iterative phase retrieval was performed using a low-energy (20-keV) electron beam to verify the possibility of high-resolution imaging with low specimen damage. Diffraction patterns of fine and uniform multi-wall carbon nanotubes (MWCNT) were recorded without a post-specimen lens. One- and two-dimensional phase retrievals were processed from the diffraction pattern alone. The reconstructed object images reflected the characteristic structure of the MWCNT. These results show the possibility of high-resolution imaging with a low-energy electron beam.
Electron Microscopy Investigation of Magnetization Process in Thin Foils and Nanostructures
Authors: Bayle-Guillemaud Pascale , Masseboeuf Aurelien , Cheynis Fabien , Toussaint Jean-Christophe , Fruchart Olivier , Gatel Christophe , Marty Alain , Bayle-Guillemaud Pascale 
Published: April 2011

AbstractThis paper presents investigations of magnetization configuration evolution during in-situ magnetic processes in materials exhibiting planar and perpendicular magnetic anisotropy. Transmission electron microscopy has been used to perform magnetic imaging. Fresnel contrasts in Lorentz Transmission Electron Microscopy (LTEM) and phase retrieval methods such as Transport of Intensity Equation (TIE) solving or electron holography have been implemented. These techniques are sensitive to magnetic induction perpendicular to the electron beam and can give access to a spatially resolved (resolution better than 10 nm) mapping of magnetic induction distribution and could be extended to dynamical studies during in-situ observation. Thin foils of FePd alloys with a strong perpendicular magnetic anisotropy (PMA) and self-assembled Fe dots are presented. Both are studied during magnetization processes exhibiting the capacities of in-situ magnetic imaging in a TEM.
Interlayer Exchange Coupling in Single Crystal Magnetic Tunnel Junctions Studied by Electron Holography
Authors: Snoeck Etienne , Tiusan Coriolan , Greullet Fanny , Benassayag Gerard , Baules Pierre , Schuhl Alain 
Published: April 2011

AbstractIon irradiation has been performed on epitaxial Fe/MgO/Fe magnetic tunnel junctions exhibiting antiferromagnetic exchange coupling. Electron holography and VSM experiments show that the amplitude and the nature of the coupling are modified by the irradiation. We demonstrate that the roughness induced by the irradiation at the Fe/MgO interfaces destroys the AF coupling. The biquadratic coupling experimentally observed in the irradiated samples is the result of the competition between local antiferromagnetic and ferromagnetic coupling. For the largest irradiation doses, the net coupling becomes ferromagnetic.