bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical Analysis of Oxygen Diffusion in monoclinic HfO2
Authors: Ikeda Minoru , Kresse Georg , Nabatame Toshihide , Toriumi Akira 
Published: April 2011

ABSTRACTIn this report, we present the detailed analysis of the interstitial oxygen (O2+, O0, O2-) diffusion in monoclinic HfO2 (hafnia) using the first principles calculations. The interstitial oxygen atom kicks out the oxygen atom at the 3-fold-site and occupies the 3-fold-site. And then the newly kicked-out interstitial oxygen atom jumps to the nearest neighbor site and couples again with the atoms at the crystal sites. This kick-out- mechanism is valid for all charge states of the interstitial oxygen in monoclinic HfO2. In hafnia, the interstitial oxygen atom can take 3 charge states (+2, 0, -2) depending on the chemical potential (Ef), whereas the oxygen-vacancy in hafnia can get +2 or 0 charge state being dependent on Ef. In the lower range of Ef, O2+ and O0 might contribute. In the middle range of Ef, the O2- does not contribute to the diffusion process in hafnia because of the pair annihilation process between O2- and oxygen vacancy (V2+) defect pair. We can simulate such a pair annihilation process in hafnia. In the higher range, O2- might contribute the diffusion process.
Study of work function of CVD WSix thin film on high K dielectric.
Authors: Maîtrejean S. , Allégret S. , Fillot F. , Farjot T. , Guillaumot B. , Passemard G. 
Published: April 2011

ABSTRACTTo meet requirements of CMOS circuits at sub 45nm scale, gate oxide thickness shall decrease. Thus high K materials are needed as dielectric gate. In this setting, due to gate depletion effect, metallic material should be used as an alternative to poly silicon gate. Moreover, specifications on threshold voltage require modulation of gate material work function with respect to nMOS or pMOS transistor. WSix work function is known to be sensitive to material stoichiometry. In this work, WSix thin films with x between 2.2 and 2.5 are evaluated as metal gate on HfO2 and SiO2 dielectric. Film chemical characteristics are correlated with work function measurements.Thin films are deposited using WF6 and dichlorosilane on a 200mm wafer industrial chamber. Thermal treatments are applied to sample in order to recrystallise the film and confirm it stability. MOS Capacitors are processed. Electrical characterizations (capacitance vs voltage) are used to extract work function with respect to film composition.Films are chemically and morphologically stable up to 800°C. A W/Si ratio gradient is observed between surface and dielectric/film interface. Whatever the nominal stoichiometry, Si/W ratio is constant at this interface. This result is correlated with identical work function measurement for different nominal stoichiometry. Moreover no differences are observed between Vfb vs equivalent oxide thickness curves for HfO2 and SiO2 dielectric. High EOT variations have been identified for SiO2 capacitors in contrast with SiO2/HfO2 capacitors. These results characterize WSix as a suitable metal gate for nMOS transistors.
Oxide Reduction in Advanced Metal Stacks for Microelectronic Applications
Authors: Qin Wentao , Volinsky Alex A. , Werho Dennis , David Theodore N. 
Published: April 2011

ABSTRACTAluminum and copper are widely used for microelectronic interconnect applications. Interfacial oxides can cause device performance degradation and failure by significantly increasing electrical resistance. Interfacial oxide layers found in Al/Ta and Ta/Cu metal stacks were studied using Transmission Electron Microscopy (TEM) combined with Energy Dispersive Spectroscopy (EDS) and Parallel Electron Energy Loss Spectroscopy (PEELS). The analysis indicates that the observed interfacial oxide layers, Al2O3 and mainly Ta2O5, result from spontaneous reductions of Ta oxide and Cu oxide, respectively. Thermodynamics enables interpretation of the results.
Long Retention Performance of a MFIS Device Achieved by Introducing High-k Al2O3/Si3N4/Si Buffer Layer
Authors: Fujisaki Yoshihisa , Iseki Kunie , Ishiwara Hiroshi 
Published: April 2011

ABSTRACTWe introduced high-k Al2O3/Si3N4 buffer layer in MFIS (Metal-Ferroelectric-Insulator-Semiconductor) devices to reduce the leakage current though the buffer (I) layer. We prepared the buffer layer by nitridizing Si substrate by atomic nitrogen radicals and then deposited Al2O3 film using ALD (Atomic Layer Deposition) technique. The interface state density between the ALD-Al2O3/Radical-Si3N4 stacked insulator and a Si substrate is as low as 1011 cm−2eV−1. The current density less than 10−9 A/cm2 is realized under the 1V bias application using films with the capacitance density of 12fF/mm2. The c-axis oriented Bi3.45La0.75Ti3O12 (BLT) ferroelectric films were deposited to make MFIS structure. With this structure, we obtained the retention time as long as 1.5×106 sec (about 17 days). This excellent retention character is attributable to the high insulating property of the ALD-Al2O3/Radical-Si3N4 stacked insulator and also attributable to the perfect elimination of defects at the interfaces in the MFIS structure.
Separation of baculoviruses using molecularly imprinted polymer hydrogels
Authors: Bolisay Linden D.V. , March John F. , Bentley William E. , Kofinas Peter 
Published: April 2011

ABSTRACTThe goal of this research is to develop molecular imprinted polymers (MIP) for biomimetic recognition of viruses. Our experimental results indicate that hydrogels can be produced, which can specifically and selectively bind recombinant baculoviruses. Although it is expected that imprinted cavities will be distorted due to the swelling of the hydrogel in water, our experiments show that even the swollen gels exhibit remarkable affinity toward recombinant baculovirus. The proposed methodologies for the synthesis and characterization of MIPs thus offer exciting avenues for the development of virus recognition techniques. The virus MIPs must function in aqueous environments. Our approach employs a more flexible non-covalent imprinting method, starting from a readily available polyamine polymer, and both MIP synthesis and testing are performed in aqueous solutions. The development of a virus imprinted MIP, which would apply to the identification, classification, and removal of viruses. This is currently a very difficult task, but the need is widespread in diverse sectors, including national security, human and animal health, crop protection, and biologics production. The development of general methods using MIPs capable of specific recognition of biological analytes would have an enormous value in medicine and bioanalytics.
Optical Transduction Schemes for Molecularly Imprinted Polymer Sensors
Authors: Murray George M. , Southard Glen E. 
Published: April 2011

ABSTRACTMolecular imprinting is a useful technique for making a chemically selective binding site. [1] The method involves building a synthetic polymeric scaffold of molecular compliments containing the target molecule with subsequent removal of the target to leave a cavity with a structural “memory” of the target. Molecularly imprinted polymers can be employed as selective adsorbents of specific molecules or molecular functional groups. Sensors for specific molecules can be made using optical transduction through chromophores residing in the imprinted site. The use of metal ions as chromophores can improve selectivity due to directional bonding. The combination of molecular imprinting and spectroscopic selectivity can result in sensors that are highly sensitive and nearly immune to interferences. [2]
Imprinting with Chemical Sensors - Challenges in Molecular Recognition and Universal Application
Authors: Dickert Franz L. , Lieberzeit Peter A. , Gazda-Miarecka Sylwia , Halikias Konstantin , Bindeus Roland 
Published: April 2011

ABSTRACTMolecular imprinting leads to functional polymers that are capable to incorporate the template used and thus lead to selective chemical sensor systems when combined with a suitable transducer. Benzene and xylene can e.g. be distinguished with a selectivity factor of nearly ten using mass-sensitive devices such as QCM and SAW, although they both contain an aromatic system and differ only by the methyl groups. Sensing materials are further tuned by using binary mixtures as templates. When analyzing polycyclic aromatic hydrocarbons (PAH) by fluorescence and QCM measurements, the sensitivity is substantially increased if a second template molecule is applied as a porogen. Capacitive sensor measurements on polymers imprinted with microorganisms, such as yeasts, show substantial sensor responses due to highly selective inclusion compared with a non-functionalised surface yielding only negligible effects.
Molecularly Imprinted Bile Acid Sequestrants: Synthesis and Biological Studies
Authors: Huval Chad C. , Chen Xi , Holmes-Farley S. Randall , Mandeville W. Harry , Polomoscanik Steven C. , Sacchiero Robert J. , Dhal Pradeep K. 
Published: April 2011

ABSTRACTNovel bile acid sequestrants based on a polyammonium backbone were synthesized using molecular imprinting technique. These imprinted polymer networks were prepared by crosslinking different polymeric amines with crosslinking agents in the presence of sodium cholate as the template. The template molecules were completely removed from the polymer matrices by repeated washings. The bile acid sequestration properties of these polymeric resins were evaluated under bothin vitroandin vivoconditions. Adsorption isotherms performed in physiologically relevant media revealed that molecular imprinting led to improvement in bile acid sequestration with about a twofold increase in the Ka(association constant). More importantly, hamsters fed with imprinted polymers in their diet excreted more bile acids than the non-imprinted control polymer. These results suggest that molecular imprinting may be potentially an interesting approach to prepare novel polymer therapeutics.
Engineering membranes for molecular recognition
Authors: Ciardelli Gianluca , Cioni Beatrice , Netri Riccardo , Porciani Francesco , Silvestri Davide , Cristallini Caterina , Barbani Niccoletta , Giusti Paolo 
Published: April 2011

ABSTRACTThe technology of molecular imprinting permits recognition sites to be inserted into a polymeric material through the polymerisation of a monomer in the presence of a template, or through the dissolution of a preformed polymer in a solution containing the template and then crosslinking or phase inversion so as to obtain the matrix-template complex. This paper will focus on the application of both techniques in the realisation of polymeric membranes with molecular recognition properties in aqueous environments.
Multi-color Luminescence from Surface Oxidized Silicon
Authors: Sato Nanoparticles K. , Hirakuri K. , Iwase M. , Izumi T. , Morisaki H. 
Published: April 2011

ABSTRACTWe fabricated the multi-color electroluminescent (EL) device using hydrofluoric (HF) acid solution treated and oxidized silicon (Si) nanoparticles. Strong red luminescence was obtained from the HF treated Si nanoparticles based EL device under a low forward bias of 4.0 V. On the other hand, green and blue luminescence, which could be seen with naked eye under room illumination, was observed for the oxidized Si nanoparitcles based EL device at the forward bias below 9.5 V, because of reduction of size due to oxidation onto the Si nanoparticle surface. Furthermore, the red/green/blue lights showed good stability for aging of a long period of time in air by the formation of oxidized layer on the surface. These results indicate that the EL devices developed in this study can realize as application to future flat panel display.
Platinum nanoparticles growth by means of pulsed laser ablation
Authors: Dolbec R. , Irissou E. , Rosei F. , Guay D. , Chaker M. , El Khakani M. A. 
Published: April 2011

ABSTRACTPlatinum nanoparticles were deposited onto Highly Oriented Pyrolitic Graphite (HOPG) substrate by laser ablating a Pt target at room temperature into a vacuum chamber. By varying the helium background pressure (from 10-5 to 0.5 Torr) and the target-to-substrate distance (from 3 to 6 cm), we were able to explore a large range of kinetic energies (i.e., from ∼4 to ∼130 eV/atom) of the Pt ablated neutrals species impinging on the HOPG substrates. Thus, the effect of the kinetic energy on the size and the surface density of Pt nanoparticles has been investigated ex-situ by means of scanning tunneling microscopy (STM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The pulsed laser deposition technique is shown to produce Pt nanoparticles (of which diameter in the 1 – 4 nm range) with a relatively narrow size distribution. While the size of the PLD Pt nanoparticles is shown to be mainly influenced by the number of laser pulses, their shape is found to be more sensitive to kinetic energy of the Pt ablated species.
Integration of fullerenes and carbon nanotubes with aggressively scaled CMOS gate stacks
Authors: Ganguly Udayan , Lee Chungho , Kan Edwin C. 
Published: April 2011

ABSTRACTHere we report the first study towards the integration of fullerenes and carbon nanotubes (CNT) in the gate stack of CMOS technology, which is a promising hybrid approach of top-down and bottom-up fabrication process. Prospective processes for C60 and CNT deposition over an aggressively scaled 2 nm gate oxide in the MOS capacitor structure have been monitored. CV measurements show minimal silicon contamination and interface states. Step charging at a specific voltage that corresponds to a fixed number density of C60 is used to establish the structural integrity and size-mono-dispersion of C60. The CV method can be further used to probe the charge injection into C60 and its anions to establish fundamental understanding of their molecular orbital (MO) structure.
Quantum Dots from Carbon Nanotube Junctions
Authors: Cleri Fabrizio , Keblinski Pawel , Jang Inkook , Sinnott Susan B. 
Published: April 2011

ABSTRACTA tight-binding hamiltonian is used to study the electronic properties of covalently-bonded, crossed (5,5) metallic nanotubes with increasing degree of disorder in the junction region. At one extreme, ideal junctions between coplanar nanotubes with a minimal number of topological defects show a good ohmic behavior. Upon increasing disorder, ohmic conduction is suppressed in favor of hopping conductivity. At the opposite extreme, strongly disordered junctions as could be obtained after electron-beam irradiation of overlayed nanotubes, display weak localization and energy quantization, indicating the formation of a quantum dot contacted to metallic nanowires by tunnel barriers.
Si-N nanowire formation from Silicon nano and microparticles.
Authors: Rath Chandana , Pinyol A. , Farjas J. , Roura P. , Bertran E. 
Published: April 2011

ABSTRACTWe report silicon nitride whisker formation from hydrogenated amorphous silicon (a-Si:H) nanoparticles grown by PECVD for the first time. We compared the results with the kinetics of whisker formation from ball milled crystalline silicon (c-Si) microparticles. Whisker formation is analyzed at different temperatures (900–1440 °C) and oxygen partial pressures. At temperatures equal or above 1350 C and at low oxygen partial pressure we observe monocrystalline α-Si3N4 whiskers having 30–100 nm diameter and several microns length. By increasing the oxygen partial pressure, the structure of whiskers is completely changed, as shown by electron microscopy. In this case we observe α-Si3N4 whiskers covered by an amorphous silica layer at 1350 C. Finally, when the precursor material is silicon microparticles, thicker (170–330 nm) and longer whiskers are formed.
Tunable Optical Absorption of Composites of Nanocrystalline Copper Prepared by in situ Chemical Reduction within a Cu2+-Polymer Complex
Authors: Huang Cheng , Huang Gang , Yang C. Z. 
Published: April 2011

ABSTRACTResearch on nanocrystalline materials and the physics behind their properties have attracted considerable attention. A number of physical and chemical techniques have been used to synthesize different nanomaterials and nanocomposites. Optical absorption characteristics of composites containing nanosized metals or semiconductors have been investigated for potential applications in nonlinear optics and photonic crystals and also to understand the effect of particle size on the band gap of the material concerned. These materials show a large third-order nonlinear susceptibility. A polymer-matrix nanocomposite containing copper particles has been prepared by in situ chemical reduction within a polymer-metal complex solid film. The copper particle size in the order of 10 nm is controlled by the initial content of the metal ions in the complex. Their fractal pattern and the value of the fractal dimension indicate that there exists a cluster-cluster aggregation (CCA) process in the present system. Optical absorption spectra of copper-polymer nanocomposites show distinct plasma absorption bands and quantum size effect in the samples. More studies on optical properties of composites containing nanosized metals are within the Drudeframe on the basis of Mie theory, but the electrons behave in a wavelike rather than a particlelike way as the particle size decreases to below 10 nm, and the classical Drude model should be modified considering the quantum confinement effect. In this paper, the calculated blueshift of the resonance peak based on a quantum-sphere model (QSM) proposed by Huang and Lue, gives remarkable agreement with the experimental data as the size of copper particles embedded in the polymer becomes smaller.
New Zinc and Cadmium Chalcogenide Structured Nanoparticles
Authors: Daniels S. M. , O'Brien P. , Pickett N. L. , Smith J. M. 
Published: April 2011

ABSTRACTThe growth of 2D quantum dot quantum well (QDQW) nanocrystals in which a shell of CdSe is grown onto cores of ZnS and capped with a further shell of ZnS is reported. The red shift in the interband absorption and photoluminescence spectrum of the quantum dots (QDs) indicates relocalization of carriers from confinement in the ZnS core to the CdSe shell. The change in interband absorption energy utilizing the effective mass approximation with spherical symmetry was modeled, enabling an estimate of the CdSe thicknesses grown. 1.8nm and 2.5nm ZnS cores were selected as the base on which to grow the CdSe shells. Despite the 12% lattice mismatch between ZnS and CdSe, our results indicate that we have successfully grown CdSe shells approximately three monolayers thick onto 2.5nm ZnS core. Anything beyond a single monolayer of CdSe could not be grown onto the 1.8nm core, although some success was observed by incorporating a CdS graded layer in-between the ZnS core and CdSe shell. The effect of ZnS shell thickness on photoluminescence efficiency has also been studied with optimum shell thicknesses showing quantum yields as high as 52%. Growth of these nanocrystals represents a significant step in the development of strained nanocrystalline heterostructures.
Synthesis and Characterization of Cd1−xCuxSe Quantum Dots
Authors: Hanif Khalid M. , Strouse Geoffrey F. 
Published: April 2011

ABSTRACTCu:CdSe nanoparticle alloys were synthesized using inorganic cluster precursor via a lyothermal method. The dots synthesized were approximately 4 nm in size and exhibited doping levels as high as 20% for Cu(I). Cu(I) cations are randomly doped on the Cd-Td site based on a Vegard's law analysis, suggesting that doping arises from a random ion substitution mechanism. The resulting dots exhibited essentially no band edge photoluminescence due to a high level of trap site inclusions in these materials resulting from Se vacancy formation in order to compensate for the Cu+ replacing a Cd2+ ion. Se vacancy formation is evident in the XPS analysis of the Cd:Cu:Se ratios for these materials.
Towards the Design and Implementation of Surface Tethered Quantum Dot-Based Nanosensors
Authors: Medintz Igor L. , Sapsford Kim E. , Golden Joel P. , Clapp Aaron R. , Goldman Ellen R. , Mattoussi Hedi 
Published: April 2011

ABSTRACTConsiderable progress has been made towards creating quantum dot (QD) based nanosensors. The most promising developments have utilized QDs as energy donor in fluorescence resonance energy transfer (FRET) processes. Hybrid QD-protein-dye complexes have been assembled to study FRET, to prototype analyte sensing and even to control or modulate QD photoluminescence. In order to transition the benefits of this technology into the field, QD-based nanosensors will have to be integrated into microtiter wells, flow cells, portable arrays and other portable devices. This proceeding describes two examples of QD-protein-dye assemblies. The first investigates the concepts of FRET applied to QD energy donors and the second describes a prototype biosensor employing QDs. We also introduce the first steps towards implementing surface-tethered QD-bioconjugates, which could potentially serve in the design of solid-state QD-based sensing assemblies.
Polarization Spectroscopy of Charged Single Self-Assembled Quantum Dots
Authors: Ware Morgan E. , Bracker Allan , Gammon Daniel , Gershoni David 
Published: April 2011

ABSTRACTWe have demonstrated single dot spectroscopy of InAs/GaAs self-assembled quantum dots embedded in a bias controlled Schottky diode. The photoluminescence spectra exhibit discrete lines depending on bias, which we attribute to the recombination of positively charged, neutral, and negatively charged confined excitons. With excitation directly into the dot, large circular polarization memory is exhibited by the two charged exciton (trion) lines. This indicates long spin lifetimes for both the electron and the heavy hole in the quantum dots.
Low Thermal Conductivity and Related Thermoelectric Properties of Zn4Sb3 and CoSb3 Thin Films
Authors: Ito Kazuhiro , Zhang Lanting , Adachi Katsuyuki , Yamaguchi Masaharu 
Published: April 2011

ABSTRACTThermal conductivity and other thermoelectric properties were investigated on β-Zn4Sb3 and CoSb3 thin films. They are prepared by co-deposition of the specific sets of Zn, Sb and Co targets by RF magnetron sputtering. Thermal conductivity measurement was performed based on an AC calorimetry method using LaserPIT. The Zn4Sb3 thin films investigated are Zn-rich with respect to the stoichiometric composition. Their thermal conductivity decrement is proportional to the reciprocal film thickness. A nano-scale grain size in a ∼350 nm-thick film specimen gives arise to an almost 50% reduction in its thermal conductivity (∼0.5W/mK) at room temperature. Low electrical resistivity and high Seebeck coefficient can be achieved simultaneously in the film specimen with properly controlled thickness and microstructure. A ZT of 1.2 at ∼460K has been obtained for the ∼350nm thick Zn4Sb3 film specimen. The minimum thermal conductivity of about 1.1 W/mK was obtained in a ∼325 nm-thick CoSb3 film specimen at room temperature.