bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioisotope Fractionation and Secular Disequilibrium in Performance Assessment for Geologic Disposal of Nuclear Waste
Authors: Murphy William M. , Pickett David A. 
Published: April 2011

ABSTRACTTwo potential applications of radioisotope fractionation and decay-series secular disequilibrium in performance assessment for geologic repositories for nuclear waste are preferential radionuclide release in source term analysis and characterization of system closure as a measure of the capacity of the geologic system to isolate waste. A primary mechanism of radioisotope fractionation is selective release and mobility of alpha decay products because of nuclear recoil effects, which is evident in natural system data. Preferential release of radioisotopes from nuclear waste forms or solubility limiting solid phases could affect repository performance; however, consequences of differential radioisotope releases are neglected in performance assessments. Decay-series disequilibria are useful also to characterize open/closedsystem behavior in natural systems. Systems that are closed on time scales that are long relative to the half-lives of decay chain nuclides achieve secular equilibrium characterized by unit activity ratios among series nuclides. For geologic disposal of nuclear waste, measures focused on chemical system closure could capture the essential characteristics of the natural system with respect to radionuclide isolation and could be based quantitatively on uranium and thorium decay series secular equilibria/disequilibria.
Comparison with Amino Group and Hydrophilic Group for Protein Afftnity by Excimer Laser Induced Functional Groups Substitution Onto Pet Film
Authors: Omuro Hitoshi , Nakagawa Masato , Fukuda Hiroaki , Murahara Masataka 
Published: April 2011

ABSTRACTPET has been widely used for medical materials such as an artificial ligament. However, the affinity of tissues is no good. To compensate this, the mesh formed PET has clinically been used for artificial ligament intruding tissue into mesh. However, this method has not shown sufficient affinity with the tissue; that is, the initial adapting strength of the material and tissue is weak. · The artificial ligament must be biocompatible to contact blood and tissue. The foregoing artificial ligament, however, doesn't satisfy the biocompatibility. ·Thus, we have modified the PET surface into hydrophilic by substituting NH2 or OH functional groups. Firstly, an ArF excimer laser light was irradiated the PET with water on top. The OH functional group was substituted on the PET surface by this photochemical reaction. Secondly, the ArF excimer laser light was irradiated the PET in ammonia gas ambient. In this photochemical reaction, the NH2 functional group was substituted on the PET surface.· In this study, the untreated sample had the contact angle with water of 80 degrees and the bonding strength with protein of only 1.0kg/cm2. The contact angle of the modified sample improved to 40 degrees and the bonding strength, to 23kg/cm2. When treated in ammonia gas, the contact angle also improved to 40 degrees; however, the bonding strength was almost the same as that of the untreated sample.It was confirmed that the affinity of the PET for water and protein could be controlled by increasing or decreasing the substitution concentration of OH and NH2 functional groups on the surface.
Application of a Non-equilibrium Green's function method to electrical transport through single molecular-assembled metallic nanoparticles
Authors: Xue Yongqiang , Ratner Mark A. 
Published: April 2011

ABSTRACTWe describe a theory of coulomb blockade of tunneling through molecular-assembled metallic nanoparticles based on the Non-equilibrium Green's function method. We apply the theory to study current transport through a single metallic nanoparticle connected to the leads through two molecular bridges with arbitrary metal-molecule coupling and electron-molecular vibration coupling. We present model calculations of the current-voltage characteristics.
Signal Propagation and Multiplexing Challenges in Electronic Textiles
Authors: Muth J. F. , Grant E. , Luthy K. A. , Mattos L. S. , Braly J. C. , Dhawan A. , Seyam A. M. , Ghosh T. K. 
Published: April 2011

ABSTRACTWeaving, knitting or placing electronic circuits within a textile matrix offer exciting possibilities for large-scale conformal circuits where the circuit dimensions can be measured on the scale of yards instead of inches. However, compared with conventional printed circuit board circuits, the textile manufacturing process and the electrical/mechanical properties of the fibers used in making the textile place unusual constraints on the electrical performance of textile circuits. In the case of distributed sensors connected via an electronic fabric, signal attenuation and the ability to form reliable interconnections are major challenges. To explore these challenges we have woven and knitted a variety of electrical transmission lines and optical fibers in fabrics to analyze their performance. The formation of interconnects and disconnects between conductors woven in textiles is also discussed, and a passive acoustic array is described as a possible electronic textile application.
Defining Flexibility and Sewability in Conductive Yarns
Authors: Orth Margaret 
Published: April 2011

ABSTRACTIn order for electronic textiles to truly qualify as textiles, they must maintain one of the intrinsic qualities of textiles, flexibility, or the ability to resist permanent deformation under bending, lateral stress and strain. Flexibility will allow electric textiles to be intimate, soft, wearable, conformable and durable. Unfortunately, flexibility is poorly understood by many researchers who come from a traditional electronics background. This paper presents some common terminology of textiles, and different approaches to understanding flexibility in fibers and yarns. Because one of the most mechanically stressful textile manufacturing process is machine sewing and embroidery, this paper defines the necessary properties of machine sewable yarns and demonstrates a formal Curl Test for judging the sewability and flexibility of stainless steel yarns. This paper also examines flexibility in yarns and fibers, historically and based on a mathematical model and more qualitative properties.
An Approach towards the Printing of Polymer Circuits
Authors: Knobloch Alexander , Bernds Adolf , Clemens Wolfgang 
Published: April 2011

ABSTRACTThe combination of soluble polymers with printing and coating techniques enabled the fabrication of polymer field-effect transistors (PFETs) on flexible films. The devices were built in a top gate configuration, with four functional layers deposited. The electrodes were patterned by gravure offset printing, where source-drain were made from conducting polyanilin and carbon black filled conducting ink was used as gate material. The doctor blading technique was utilized for coating low viscosity solutions, where Poly(3-alkyllthiophene) served as active semiconductor material. Thus completely printed PFETs have been demonstrated. Further steps for printing integrated polymer circuits included the fabrication of inverters combined from two printed. Screen-printing could be used as an alternative to coating and has the potential to enable vertical electrical interconnects between top and bottom layer of circuits. To test the suitability insulating layers were screen-printed homogenously onto lithographically patterned electrodes made from gold. The PFETs' yield was sufficient enough to let a 7-stage ring oscillator work with a clock frequency of 4 Hz.
CdSe Nanoparticle/Metal-Organic Inks For Printable Electronics
Authors: Schulz Douglas L. 
Published: April 2011

ABSTRACTThe research objective of this project was the spray deposition of CdSe films using a nanoparticle CdSe suspension as the precursor ink. This ink consisted of CdSe nanoparticles (nano-CdSe) mixed with a “reactive dispersant” in a non-aqueous solvent. The reactive dispersant, a metal-organic molecule, served two purposes; (1) to form a dispersed CdSe suspension at room temperature, and (2) to thermally “unzip” giving CdSe and a byproduct. The CdSe thereby formed could be deposited at the grain boundaries and serve to physically and electrically connect the CdSe nanoparticles at moderate, plastic-compatible temperatures. If electronics-grade CdSe layers could be produced at low deposition temperatures, this approach may be applicable to printed CdSe-based thin film field-effect transistors (TFTs) on flexible substrates.
Nonlinear Carrier Relaxation in a Single GaAs Self-organized Quantum Dot
Authors: Kuroda T. , Sanguinetti S. , Minami F. , Gurioli M. , Watanabe K. , Koguchi N. 
Published: April 2011

ABSTRACTWe resolved a photoemission signal from a single self-organized GaAs/Al0.3Ga0.7As quantum dot (QD) with picosecond time resolution. The emission spectra consisting of the multiexciton structures are observed to depend on the delay time and the excitation intensity. Through the analysis we can determine the carrier relaxation time as a function of population of photoinjected carriers. Enhancement of the intra-dot carrier relaxation is demonstrated to be due to the carrier-carrier scattering inside a single QD.
Influence of In0.2Ga0.8As strain-reducing layer on the active region of quantum dot superluminescent diodes
Authors: Zhang Z. Y. , Li Ch. M. , Jin P. , Meng X. Q. , Xu B. , Ye X. L. , Wang Z. G. 
Published: April 2011

ABSTRACTWe have investigated the optical properties of asymmetric multiple layer stacked self-assembled InAs quantum dot with different interlayer. We found that asymmetric multiple stacked QD samples with In0.2Ga0.8As + GaAs interlayer can afford a 180nm flat spectral width with strong PL intensity compared to other samples at room temperature. We think this result is due to the introduction of In0.2Ga0.8As strain-reducing layer. Additionally, for the broad spectral width and the strong PL intensity, this structure can be a promising candidate for quantum-dot superluminescent diodes.
Optical Properties of InAs/InP Planar Quantum Dot Microcavities
Authors: Dalacu Dan , Poitras Daniel , Lefebvre Jacques , Poole Philip J. , Aers Geoff C. , Williams Robin L. 
Published: April 2011

ABSTRACTPlanar InAs/InP quantum dot microcavities using multi-layer SiO2/Ta2O5 Bragg reflectors have been studied in emission. The spectra exhibit collection optics-limited cavity linewidths of ∼1meV with the occasional ∼200μeV single-dot emission. Measurements as a function of incident power show quantum dot saturation behavior, with transfer of oscillator strength to the wetting layer outside the cavity stop band. Saturation behavior at fixed pump power is also observed as a function of decreasing temperature. Dispersion measurements as a function of emission angle show polarization splitting in qualitative agreement with theory.
Effect Of Phosphorus On Ge/Si(001) Island Formation
Authors: Kamins Theodore I. , Medeiros-Ribeiro Gilberto , Ohlberg Douglas A. A. , Stanley Williams R. 
Published: April 2011

ABSTRACTWhen Ge is deposited epitaxially on Si, the strain energy from the lattice mismatch causes the Ge in layers thicker than about four monolayers to form distinctive, three-dimensional islands. The shape of the islands is determined by the energies of the surface facets, facet edges, and interfaces. When phosphorus is added during the deposition, the surface energies change, modifying the island shapes and sizes, as well as the deposition process. When phosphine is introduced to the germane/hydrogen ambient during Ge deposition, the deposition rate decreases because of competitive adsorption. The steady-state deposition rate is not reached for thin layers. The deposited, doped layers contain three different island shapes, as do undoped layers; however, the island size for each shape is smaller for the doped layers than for the corresponding undoped layers. The intermediate-size islands are the most significant; the intermediate-size doped islands are of the same family as the undoped, multifaceted “dome” structures, but are considerably smaller. The largest doped islands appear to be related to the defective “superdomes” discussed for undoped islands. The distribution between the different island shapes depends on the phosphine partial pressure. At higher partial pressures, the smaller structures are absent. Phosphorus appears to act as a mild surfactant, suppressing small islands.
Estimation of Silicon Nanocrystalline Sizes from Photoluminescence Measurements of RF Co-Sputtered Si/SiO2 Films.
Authors: Ramírez-Porras A. , Fonseca L.F. , Resto O. 
Published: April 2011

ABSTRACTA stochastic distribution of nanocrystalline sizes model is applied to fit photoluminescence (PL) spectra of luminescent Si nanocrystals in a Si/SiO2 matrix synthesized by RF co-sputtering on the top of quartz substrates. With this method, the PL spectra from a diverse set of samples can be resolved mainly as the sum of two components: a contribution from a gaussian-like distribution of sizes of quantum dots (QD) and a similar component from a distribution of quantum wires (QW). These distributions of sizes and their associated PL energies agree well with the so-called Smart Quantum Confinement model (SQC).
Polarization Anisotropy in Electroreflectance Spectrum of Porous Silicon
Authors: Toyama Toshihiko , Nakai Yasuharu , Moriguchi Koji , Okamoto Hiroaki 
Published: April 2011

ABSTRACTLinearly polarized electroreflectance (ER) measurements have been firstly performed on PSi with near-normal incident (NNI) and glancing-angle incident (GAI) light. In the NNI geometry, no significant polarization anisotropy is observed. Meanwhile, in GAI geometry, a clear polarization anisotropy is observed. The s-polarized ER spectrum consists of the ER features corresponding to those found in the NNI geometry, while in the p-polarized ER spectrum, the two features found in s-polarized spectrum in infrared-visible region are not found, while a new feature is observed at ∼2.1 eV. The mechanism of the unusual polarization anisotropy is discussed in association with structural anisotropy of PSi.
Investigation on Process Dependence of Self-Assembled Metal Nanocrystals
Authors: Lee Chungho , Liu Zengtao , Kan Edwin C. 
Published: April 2011

ABSTRACTWe report the systematic characterization of metal nanocrystal formation on ultra-thin tunnel gate oxide (2∼3nm) for memory applications. To get a high density and small average size of nanocrystals, the process parameters including annealing temperature, initial film thickness, and substrate doping are investigated for Au, Ag, and Pt nanocrystal formation with Si nanocrystal structure as control samples. The observation of nanocrystal formation by scanning electron microscope (SEM) shows that annealing below melting temperature of deposited film contributes to the reshaping of nanocrystals, while the initial film thickness to actual nanocrystal growth. In addition, the Schottky charge effect from substrate doping is not negligible if the tunnel oxide is thin. Controlling the process parameters, Au, Ag, and Pt nanocrystals of 4.0×1011cm-2, 2.8×1011cm-2, and 2.4×1011cm-2 can be formed with mean size of 6.2nm, 6.6nm, and 8.0nm, respectively. The observation of nanocrystals by scanning transmission electron microscope (STEM) shows that nanocrystals are spherical and crystalline. Metal contamination to the Si/SiO2 interface is also closely monitored with many process recipes of metal nanocrystal formation on 2∼3nm oxide showing atomically clean interface. Electrical evaluation of nanocrystal formation is carried out by C-V measurements of metal-oxide-semiconductor (MOS) capacitors with embedded metal nanocrystals.
The Microstructure of Co Nanoparticles Directly Deposited on Si (001) Substrates Using DC Magnetron Sputtering
Authors: Chung Bing-Xian , Liu Chuan-Pu , Chen Jiun-Nan 
Published: April 2011

ABSTRACTDispersive cobalt nanoparticles are fabricated directly on Si (001) substrates by DC magnetron sputtering at room temperature. During deposition, the parameters chosen for the investigation are substrate bias (from +525 To –100 Volts), target-to-substrate distance (from 6 to 12 cm) and deposition time (from 10 to 30m sec), while the other parameters are kept the same, including the power of 50 watts. Atomic force microscope (AFM) is employed to determine the density and morphology of cobalt nanoparticles whereas high-resolution electron microscope (HRTEM) is used to visualize the resulting microstructure in the nanoparticles. It is found that Co nanoparticle array can be formed by combining the optimum substrate bias and target-to-substrate distance. The size uniformity of the nanoparticle array can be enhanced by positive bias due to charging effects. The nanoparticle of as small as a few nanometers can be successfully fabricated by DC-sputtering and can be applied to nanotube growth as catalysts.
Construction of Spherical Assembly of Gold Nanoparticles Using Tetra[(methylthio)methyl] silane as Ligand
Authors: Maye Mathew M. , Lim I-Im S. , Luo Jin , Han Li , Rabinovich Daniel , Chen Sandy , Maye Michael P. , Zhong Chuan-Jian 
Published: April 2011

ABSTRACTThis paper reports a study on the assembly of gold nanoparticles via a tetradentate organosulfur ligand, tetra[(methylthio)methyl] silane. We have characterized the evolution of the assembly from individual nanoparticles to spheres (30 ∼ 160 nm) of linked nanoparticles using UV-Visible, TEM, and AFM techniques. We have also demonstrated that the assemblies could be effectively disassembled via manipulating the ligand chemistry. Intriguing assembly-substrate interactions were observed, which could be related to interfacial hydrophobicity. Implications of these findings to the development of abilities in interfacial manipulation of the nanostructures are also discussed.
The Effect of Nanotube Loading and Dispersion on the Three-Dimensional Nanostructure of Carbon Nanotube-Conducting Polymer Composite Films
Authors: Hughes Mark , Chen George Z. , Shaffer Milo S. P. , Fray Derek J. , Windle Alan H. 
Published: April 2011

ABSTRACTNanoporous composite films of multi-walled carbon nanotubes (MWNTs) and either polypyrrole (PPy) or poly(3-methylthiophene) (P3MeT) were grown using an electrochemical polymerization technique in which the nanotubes and conducting polymer were deposited simultaneously. The concentration and dispersion of MWNTs in the polymerization electrolyte was found to have a significant effect on the thickness of polymer coated on each MWNT and hence the loading of MWNTs in the films produced. It has been shown that for an increasing concentration of MWNTs in the polymerization electrolyte, the thickness of polymer coated on each MWNT decreases. This relationship made it possible to minimize ionic diffusion distances within the nanoporous MWNT-PPy films produced, reducing their electrical and ionic resistance and increasing their capacitance relative to similarly prepared pure PPy films.
Terahertz-Emitting Silicon-Germanium Devices
Authors: Troeger Ralph T. , Adam Thomas N. , Ray Samit K. , Lv Pengcheng , Lehmann Ulrike , Kolodzey James 
Published: April 2011

ABSTRACTIn this paper we report on far-infrared emission in the 1–12 THz frequency range from strained SiGe structures. Pseudomorphic superlattices were grown by Molecular Beam Epitaxy (MBE) at the relatively low substrate temperature of 400°C to prevent germanium segregation. Layer thicknesses, composition, and crystallinity were confirmed by high-resolution X-ray diffraction. Devices were designed to produce confined hole states with various energy separations. Mesa devices were etched in a reactive-ion etching system and tested for edge emission over a wide range of drive currents using an FTIR spectrometer in step-scan mode. THz emission was observed in pulsed mode at current densities as low as 50 A/cm2 and at temperatures as high as 50 K, using a liquid-helium-cooled silicon bolometer detector with a lock-in amplifier. Emission spectral peaks occurred at 7.9 and 9.36 THz for two different samples, in good agreement with k·p calculations.
Amorphous-Microcrystalline Silicon Films Obtained Using Hydrogen Dilution in a DC Saddle-Field Glow-Discharge
Authors: Allen T. , Milostnaya I. , Yeghikyan D. , Gaspari F. , Kherani N.P. , Kosteski T. , Zukotynski S. 
Published: April 2011

ABSTRACTAmorphous-microcrystalline Si has been grown with hydrogen dilution using the DC saddle-field glow-discharge deposition technique. The five-electrode saddle-field system allows for independent control of the discharge parameters and of the substrate bias. The film structure was studied using Raman spectroscopy and SEM. We find that the structure of the films depends mainly on hydrogen dilution, substrate bias, electrical conductivity of the substrate, and chamber pressure. The deposition conditions, which promote growth of microcrystals, have been identified. It was found that the local electric field at the substrate surface plays a key role in obtaining microcrystallinity.
Tunnel Currents in the Photo-Field Detectors and the Auger Transistor under Strong Electric Field
Authors: Kalganov Vladimir D. , Mileshkina Nina V. , Ostroumova Elena V. , Rogacheva Ekaterina A. 
Published: April 2011

ABSTRACTThe photo-field emission properties of semiconductors at a very strong electric field together with tunnel electron emission in metal-insulator-semiconductor heterostructures with a tunneltransparent layer of an insulator was studied. It was found that a self-consistent quantum well near the surface of semiconductor emitter tips can change the spectral region of photosensitivity of the radiation semiconductor field emitter detectors, and leads to the significant increase in their photosensitivity [1]. Also the appearance of a self-consistent quantum well near the semiconductor surface is the key factor which allows to use the metal-insulator heterojunction in the development of an Auger transistor based on the Al-SiO2-n-Si structure - the fastest operation semiconductor bipolar transistor [2–4]. Conditions for appearance of a self-consistent quantum well under strong electric field in both the near-surface region of a vacuum semiconductor field-emitter and metal-insulator-semiconductor heterostructures (Auger transistor) were studied also.
Structural, optical and electrical properties of the novel semiconductor alloy ZnOxTe(1-x)
Authors: Porter H. L. , Jin C. , Narayan J. , Cai A. L. , Muth J. F. , Holland O. W. 
Published: April 2011

ABSTRACTEpitaxial films of undoped ZnOxTe(1-x) have been prepared on double-side polished c-axis oriented sapphire substrates with pulsed laser deposition. The method of epitaxial growth is expected to have the same domain matching epitaxial relationship with sapphire as does pure ZnO, where six lattice planes of ZnOxTe(1-x) match with seven lattice planes of sapphire [1,2]. High quality, single crystal, epitaxial alloys with around 4% Te have been grown that demonstrate excellent optical properties and a pronounced, sharp excitonic peak, in optical transmission. The incorporation of Te makes the compound more covalent, and less ionic than pure ZnO. Transmission electron microscopy (TEM) demonstrates single-crystal growth with a sharp interface. The low-resolution X-ray diffraction (XRD) pattern of ZnOxTe(1-x) films is almost indistinguishable from those of pure ZnO, except a usually diminished intensity of the (0004) peak. The incorporation of Te in ZnO was verified by a shift in excitonic peak position in absorption, and through a shift in cathodoluminescence (CL) peak. X-ray photoelectron spectroscopy (XPS) data verifies incorporation of telluride chemical state of tellurium atoms. Rutherford backscattering/channeling (RBS/C) confirmed crystal quality for the pure ZnO films. Hot-point probe measurements indicate as-grown, undoped films to be somewhat higher in resistivity than pure ZnO with inconclusive carrier type, as compared to the naturally n-type ZnO. This may be a consequence of the more covalent bonding between Zn and Te and suggests a possible strategy for p-type doping.