bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and Characterization of Cobalt-filled Carbon Nanotubes Prepared by a Simple Catalytic Method
Authors: Ma Xicheng , Cai Yuanhua , Li Xia , Lun Ning , Wen Shulin 
Published: June 2019

AbstractHigh-quality cobalt-filled carbon nanotubes (CNTs) were prepared in situ in the decomposition of benzene over Co/silica-gel nano-scale catalysts. Unlike the previous reports, the catalysts needn't be pre-reduced prior to the forming of Co-filled CNTs, thus the advantage of this method is that Co-filled CNTs can be produced in one step, at a relatively low cost. Transmission electron microscopy (TEM) investigation showed that the products contained abundance of CNTs and most of them were filled with metallic nanoparticles or nanorods. High-resolution TEM (HRTEM), selected area electron diffraction (SAED) patterns and energy dispersive X-ray spectroscopy (EDS) confirmed the presence of Co inside the nanotubes. The encapsulated Co was further identified always as high temperature alpha-Co phase with fcc structure, which frequently consists of twinned boundaries and stacking faults. Based on the experimental results, a possible growth mechanism of the Co-filled CNTs was proposed.
Mirrorless Lasing in Liquid Crystalline Photonic Bandgap Materials
Authors: Cao Wenyi , Muñoz Antonio , Palffy-Muhoray Peter , Taheri Bahman 
Published: June 2019

AbstractLiquid crystals (LC) are promising photonic bandgap (PBG) materials. Certain LC phases have spatially modulated ground states and effectively form self-assembled PBG structures. These structures can also be made permanent by photopolymerization. Typically, LCs respond readily to applied fields, enabling modulation and switching of the bandgap. Since classical light propagation is forbidden, fluorescent emission in the band gap can lead to population inversion and stimulated emission at the band edges. Mirrorless lasing experiments provide an effective probe of the bandgap. We discuss the underlying physics, and present the results of mirrorless lasing in a variety of cholesteric LC materials, including recent results of photon counting statistics and 3-D lasing in the cholesteric blue phase.
Nano-wire field-effect transistor in etched ion tracks of flexible polymer foils
Authors: Chen Jie , Klaumünzer S. , Könenkamp R. 
Published: June 2019

AbstractWe have used irradiation by fast heavy ions and subsequent etching to prepare cylindrical channels in polymer/metal/polymer stacks. These channels were subsequently filled with insulator and semiconductor material, and then provided with suitable metallic contacts, to obtain a vertical field-effect transistor device. Preparation and first electronic results on this new device are reported. Typically 107 to 108 transistors per cm2 with a diameter of ∼100 nm can be obtained in this technique. The fabrication does not require lithography on the scale of a single transistor, and is suitable for large-area applications. The embedding in a soft polymer matrix results in a robust arrangement, whose electronic characteristics are largely insensitive to mechanical stress. At the present stage of development the smallest dimension of a single transistor grown by this technique is ∼50 nm. Further reduction of the device dimensions appears possible and, with it, observation of single electron effects in these devices.
Formation ofWell-defined Nanocolumns by Ion Tracking Lithography
Authors: Felter T.E. , Musket R. G. , Macaulay J. , Contolini R. J. , Searson P. C. 
Published: June 2019

AbstractLow dimensional systems on the nanometer scale afford a wealth of interesting possibilities including highly anisotropic behavior and quantum effects. Nanocolumns permit electrical and mechanical contact, yet benefit from two confined dimensions. This confinement leads to new optical, mechanical, electrical, chemical, and magnetic properties. We construct nanocolumn arrays with precise definition and independent control of diameter, length, orientation, areal density and composition so that geometry can be directly correlated to the quantum physical property of interest. The precision and control are products of the fabrication technique that we use. The process starts with an ion of sufficient energy to “track” a dielectric such as a film applied uniformly onto a substrate. The energy loss of the ion alters chemical bonding in the dielectric along the ion's straight trajectory. A suitable etchant quickly dissolves the latent tracks leaving high aspect ratio holes of small diameter (∼10nm) penetrating a film as thick as several microns. These small holes are interesting and useful in their own right and can be made to any desired size by continuing the etching process. Moreover, they serve as molds for electrochemical filling. After this electrodeposition, the mold material can be removed leaving the columns firmly attached to the substrate at the desired orientation. A variety of structures can be envisioned with these techniques. As examples, we have created arrays of Ni and of Pt nanocolumns (∼ 60 nm diameter and ∼ 600 nm long) oriented perpendicular to the substrate. The high aspect ratio and small diameter of the columns enables easy observation of quantum behavior, namely efficient electron field emission and Fowler Nordheim behavior.
Effect of Annealing on the Characteristics of Silicon Implanted Nano/trap Crystal Memories
Authors: Kalkur T.S. , Cramer Nick , Philofsky Elliott , Kammerdiner Lee 
Published: June 2019

AbstractIn this paper we are presenting the results of silicon nano-trap memory fabricated by implanting high dose silicon into gate oxide of thickness 30 nm. The gate oxide was grown by dry oxidation. Capacitance versus voltage characteristics of MOS (metal oxide silicon) structures with silicon implanted samples annealed in nitrogen environment at a temperature of 950 °C show a memory window depending on the applied DC bias voltage. A memory window of 3V was obtained for an applied bias voltage of ± 10V. Annealing of the MOS structures in a furnace at a temperature of 800 °C for 30 minutes in oxygen resulted in complete loss or collapse of the memory window. Annealing the samples rapid thermally in oxygen environment at 800 oC for 30 seconds, resulted in a memory window of about 2 Volts for an applied voltage of ± 14V.
Energy transport in metal nanoparticle plasmon waveguides
Authors: Maier Stefan A. , Kik Pieter G. , Sweatlock Luke A. , Atwater Harry A. , Penninkhof J. J. , Polman A. , Meltzer Sheffer , Harel Elad , Requicha Ari A.G. , Koel Bruce E. 
Published: June 2019

AbstractWe investigate the optical properties of arrays of closely spaced metal nanoparticles in view of their potential to guide electromagnetic energy with a lateral mode confinement below the diffraction limit of light. Finite-difference time-domain simulations of short arrays of noble metal nanospheres show that electromagnetic pulses at optical frequencies can propagate along the arrays due to near-field interactions between plasmon-polariton modes of adjacent nanoparticles. Near-field microscopy enables the study of energy transport in these plasmon waveguides and shows experimental evidence for energy propagation over a distance of 0.5 νm for plasmon waveguides consisting of spheroidal silver particles fabricated using electron beam lithography.
Ion Beam Synthesis and Optical Properties of Zn and Zno Nanocrystals in Sio2 and Caf2 Substrates
Authors: Liu Y.C. , Mu R. , Xu H.Y. , Lu Y.M. , Shen D.Z. , Fan X.W. , Henderson D. O. , White C.W. 
Published: June 2019

AbstractIon implantation was used to inject zinc ions into crystalline CaF2 and amorphous SiO2 substrates. Zn or ZnO nanoparticles were formed after annealing in a reducing (4% H2 + 96%Ar) or an oxidizing (10%O2 + 90% Ar ) atmosphere, respectively. When the sample was annealed in a reducing atmosphere, the absorption band at ∼ 5.3 eV for zinc implanted into SiO2 was attributed to zinc metal colloids. The absorption peak observed in the 4.3 – 4.7 eV region was due to the formation of ZnO nanocrystals, after the sample was annealed in an oxidizing environment. Both X-ray diffraction (XRD) and X-ray photospectroscopy (XPS) were used to confirm ZnO nanocrystal formation. For zinc implanted into CaF2, the as-formed ZnO nanocrystals were aligned with their [002] axes parallel to the [111] axis of the CaF2. Photoluminescence (PL) spectra showed UV and green emission from the zinc-implanted silica samples annealed under an oxygen atmosphere; however, no green emission was observed for ZnO formed in a CaF2 substrate. An additional emission was observed at ∼ 420 nm which might be due to F centers in CaF2 created by ion beam damage.
A Comparative Study on the Differences in the Evolutions of Thin Film Morphologies of Co-Al Binary System: Molecular Dynamics Study
Authors: Kim Sang-Pil , Lee Seung-Cheol , Lee Kwang-Ryeol , Lee Kyu-Hwan , Chung Yong-Chae 
Published: June 2019

AbstractThe morphology evolution of thin films was studied by molecular dynamics simulation. In this simulation four deposition and substrate elements combinations were used: Al on Al(001), Al on Co(001), Co on Co(001), Co on Al(001). The Al thin film was always grown by layer-bylayer mode regardless of substrates used. On the other hand, thin films formed by Co deposition depended on substrates used.While Co thin films on the Co substrates were grown by the island mode, a 3 monolayer (ML) thickness of CoAl surface compound was initially formed on Al substrate, before pure Co thin film growth occurred. In addition to the study on morphologies, the degrees of mixing of atoms in the interface were studied quantitatively. No surface mixing and a sharp interface were observed when Co was used as a substrate regardless of deposited atoms. On the contrary, a large amount of surface mixing or compound formation was observed when Al was used as a substrate.
Study of the Effects of Heavy-Ion Radiation on Nanocomposite Carbon Films
Authors: Kristian Kathleen E. , Medina-Emmanuelli Nadia M. , Ortiz Oscar O. , González Adolfo , González Juan A. , Jesús JoelDe , Vargas Iris M. , Weiner Brad R. , Morell Gerardo 
Published: June 2019

AbstractThe compositional and microstructural transformations induced by heavy ions (GeV/amu Fe and Si ions) on nanocomposite carbon (n-C) films were investigated by Raman Spectroscopy (RS), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectrscopy (XPS). Two identical sets of n-C films were prepared in a sulfur-assisted hot filament chemical vapor deposition (HFCVD) system using methane, hydrogen and hydrogen sulfide. Films with various sp3 C and sp2 C bonding distributions were present within each set, which were obtained by varying the substrate temperature (400-600 °C). One set of films was submitted to a 20 krad dose of energetic Si and Fe ions at the NASA space radiation simulation facility hosted in Brookhaven National Laboratory's Alternating Gradient Synchrotron (AGS). All the films showed the characteristic diamond (tetragonal sp3 C) band at around 1332 cm-1 and the graphitic (trigonal sp2 C) D and G bands at around 1350 and 1590 cm-1, respectively, evidencing their composite nature. The results indicate that sp2 C ←sp3 C interconversions take place in the nanocomposite carbon material during heavy ion irradiation. A mechanism is proposed to explain this behavior. The overall results imply that there could be a range of sp3/sp2 C ratios for which carbon bonding interconversion takes place under ion radiation without significant changes to the average composition of the material. Nanocomposite carbon materials with this characteristic would be radiation insensitive. A technique could be developed based on this carbon bonding interconversion property by using focused energetic beams onto carbon films to produce a robust information storage technology that would survive catastrophic events.
Observation of ion-induced ripples in Cu(001)
Authors: Chan Wai Lun , Pavenayotin Niravun , Chason Eric 
Published: June 2019

AbstractA linear instability theory proposed by Bradley and Harper accounts for many of the features of ripple formation on amorphous and semiconductor surfaces, but it is not consistent with measurements of sputtered metal surfaces. In the present work, we report observations of sputter ripples on Cu(001) surfaces which are similar to amorphous and semiconductor systems. By using higher ion flux and temperature than previously used, we have produced ripples in which the wavelength is independent of time and the amplitude increases exponentially during the early stages of growth. The ripple evolution was measured using in situ light scattering during sputtering.
Ion beam lithographic fabrication of ordered VO2 nanoparticle arrays
Authors: Lopez R. , Suh J. Y. , Feldman L. C. , Haglund R. F. 
Published: June 2019

AbstractLong-range ordered arrays of vanadium dioxide nanoparticles are fabricated by pulsed laser deposition in a patterned layer of poly(methyl methacrylate) resist. The two- dimensional arbitrary pattern is created by focused ion beam exposure of the resist, followed by pulsed laser deposition and thermal annealing. Interaction of light with the nanoparticles is controlled by their geometrical arrangement as well as by the difference in optical properties displayed between the metallic and semiconducting phases of VO2. Arrays like this open opportunities to study optical resonances and interactions for nanoparticles in close proximity, in the framework of the metal-semiconductor phase transition in VO2.
Two-Dimensional Differential Adherence and Myoblast Alignment Driven Fabrication of Engineered C2C12 Muscle Organoids
Authors: Patz Tim M. , Doraiswamy Anand , Narayan Roger , Modi Rohit , Chrisey Douglas 
Published: June 2019

ABSTRACTDifferential adherent surfaces were used to induce attachment of C2C12 myoblasts that later would form engineered muscle organoids. Narrow channels, 60–400 μm wide, were micromachined in a 2% agarose gel using an ArF laser, and subsequently filled with extracellular matrix. Upon addition of 1 mL of a 2×104 cells/mL myoblast suspension, cells selectively adhered to the ECM lined channels in a non-confluent manner and we monitored their growth at various time points. The adherent myoblasts were flourescently imaged with a propidium iodide live/dead assay, which revealed that the cells were alive within the channels. After 72 hours growth, the myoblasts grew, proliferated and differentiated into myotubes. Myoblasts residing in the narrow channels (60–150 μm wide) aligned parallel to the channel, while myoblasts adhered to the wide channel (400 μm) were randomly aligned within the channel. The fully-grown 1 cm long organoids maintained an aspect ratio on the order of 100:1. These results provide the foundation for future three-dimensional tissue growth using differential adherent
Direct Laser Sintering of metal parts: characterisation and evaluation of joining mechanisms
Authors: Bassoli E. , Gatto A. , Iuliano L. , Atzeni E. 
Published: June 2019

ABSTRACTRapid Prototyping and Tooling are playing a more and more important role in the achievement of compressed time-to-market solutions, where prototype parts and tools are produced directly from the CAD model. In particular, Selective Laser Sintering (SLS) of metal powders with liquid phase is frequently applied for the production of inserts for injection moulding of plastic parts.An experimental campaign has been planned to investigate the surface finish and mechanical performances of Direct Laser Sintering technique, with particular regard to the effect of the laser sintering strategy on the anisotropy of the final part. Tensile specimens of DirectMetal 20 and DirectSteel 20 materials have been produced, with different orientations in regard to laser path.Rupture surfaces after the tensile tests were observed at the SEM, in order to understand failure mechanisms, whereas the observation of polished sections helped investigating joining phenomena between the particles. The proposed experimental methodology allowed correlating the macroscopic performances to the micro-mechanisms ruling the process, proving that no considerable differences can be noticed between samples produced in the X and Y direction within the plane of powder deposition.
Effect of Ink Properties through Various Sol-Gel Synthesis Routes for the Ink-Jet Deposition of YBa2Cu3O7−δ Superconducting Layers
Authors: Mouganie T. , Glowacki B. A. 
Published: June 2019

AbstractThe development of ink synthesis for YBa2Cu3O7−δ (YBCO) coated conductors is discussed in detail. These chemical solution deposition (CSD) processes are for drop-on-demand ink-jet coating and ink-jet printing allowing non-vacuum formation of multi-layer superconducting patterns on metal substrates (with and without the aid of buffer layers).Printing and substrate parameters that alter solid-liquid interface properties were investigated, and the sol-inks synthesised were aqueous and non-aqueous based therefore allowing variable chemical properties depending on what was required from the deposition process. The formation and the stability of the sol-inks has been studied and discussed, with the various synthesis steps and additives yielding the properties required to produce coatings.Characterisation of the inks was by Differential Thermal Analysis and Thermal Gravimetry whilst characterisation of the coatings and products was by X-Ray Diffraction and Scanning Electron Microscopy. AC susceptibility was used to assess the superconductivity of the printed samples.
Characterisation of innovative materials for Direct Laser Sintering
Authors: Bassoli E. , Gatto A. , Iuliano L. , Atzeni E. 
Published: June 2019

ABSTRACTThe performances achieved by Rapid Prototyping techniques are progressively leading towards Rapid Manufacturing, that is the capability to produce end products, directly from the CAD model. Even so, the diffusion of these techniques is hardly supported by scientific knowledge about the micro-mechanisms ruling the macroscopic performances of the part. In the present research, mechanical performances of new materials produced by Direct Laser Sintering technique have been studied: a Polyamide and an innovative Polyamide-Aluminium composite (Alumide). Specimens were produced with different orientations in regard to powder deposition plane and laser path, to investigate how the manufacturing anisotropy affects the part performances.
Broadening Middle-School Students' Images of Science and Scientists
Authors: Leslie-Pelecky Diandra L. , Buck Gayle A. , Zabawa Angela 
Published: June 2019

ABSTRACTThe ‘mad scientist’ stereotype is alive and well – and not an image most K-12 students can (or want to) embrace. Project Fulcrum, a National Science Foundation-funded GK-12 program, partners math, science and engineering graduate students with elementary and middle-level teachers. One project goal – broadening student images of science and scientists –is addressed by projects developed by the teacher/scientist teams that are focused on the specific needs of their students. The projects developed focus on scientists, the use of science in different types of jobs, and developing scientific skills. Pre-project research, in which teachers probe the motivation behind their students’ attitudes, is a critical component of developing a successful project. Although determining the specific impact of this project on student attitudes is complicated by its being part of a larger project, teachers and scientists report enhanced awareness of student attitudes and the reasons underlying those attitudes, and generated ideas to address those motivations.
A study of V3+ and the Vanadium acceptor level in semi-insulating 6H-SiC
Authors: Lee Wonwoo , Zvanut Mary E. 
Published: June 2019

AbstractInfrared absorption (IR) and electron paramagnetic resonance (EPR) spectroscopies are used to study the V3+ impurity and the vanadium acceptor level in 6H semi-insulating SiC. IR and EPR data obtained from samples cut from the same wafer support the assignment of the 0.60 and 0.62 eV IR absorption lines to substitutional V3+. Photo-induced EPR measurements reveal identical photo-thresholds for V3+ and V4+ ions. A peak at 0.8 eV, where the intensity of the three plus charge state decreases and the four plus charge state increases by an equal amount, is thought to represent excitation of an electron from V3+ to the conduction band edge. The 0.8 eV peak is therefore attributed to the V3+/4+ level. The difference between the optically measured value reported here and that measured previously using temperature dependent techniques is attributed thermal relaxation.
Role of the Substrate Doping in the Activation of Fe2+ centers in Fe implanted InP
Authors: Cesca T. , Gasparotto A. , Mattei G. , Verna A. , Fraboni B. , Impellizzeri G. , Priolo F. 
Published: June 2019

AbstractWe have investigated the structural and electrical behavior of Fe centers introduced in InP by high temperature ion implantation. The lattice location of the Fe atoms and the effect of postimplantation annealing treatments have been studied by PIXE-channeling measurements. I-V, CV and DLTS analyses have been used to characterize the electrical properties related to the presence Fe2+/3+ deep traps. The results show that the background n-doping density play a crucial role in controlling the annealing behavior and the electrical activation of the Fe centers. The same effect has been observed in samples containing Fe concentrations both above and below the Fe solubility threshold in InP.
A Pulsed EDMR Study of Charge Trapping at Pb Centers
Authors: Boehme Christoph , Friedrich Felice , Lips Klaus 
Published: June 2019

AbstractLow temperature pulsed electrically detected magnetic resonance (pEDMR) measurements of charge trapping and recombination transitions involving Pb centers at the c-Si (111)/SiO2 interface are presented. The results of these experiments show that when a conduction electron is trapped, it forms a strongly coupled spin pair with the defect electron prior to its readjustment into the charged Pb ground state. The data reveals that the Landé factors of the two electrons within these pairs are almost identical (difference < 0.002) and that they are, within the measurement accuracy, identical to the Landé factor of the uncharged, singly occupied Pb center. From this, it is concluded that trapping and recombination at Pb defects is dominated by direct charge capture and not by tunneling or hopping transitions from other localized states. Different cross sections attributed in previous studies to different interface defects at the c-Si/SiO2 interface can be explained by readjustment out of different spin configurations of the charged Pb-* defect.
Investigation of GaNAsSb/GaAs and GaInNAsSb/GaNAs/GaAs Band Offsets
Authors: Yuen Homan B. , Kudrawiec Robert , Ryczko K. , Bank S.R. , Wistey M.A. , Bae H.P. , Misiewicz J. , Harris J.S. 
Published: June 2019

AbstractHeterojunction band offsets of GaNAsSb/GaAs, GaInNAsSb/GaAs, and GaInNAsSb/GaNAs/GaAs quantum well (QW) structures were measured by photoreflectance (PR) spectroscopy. These samples were grown by solid-source molecular beam epitaxy using a radio-frequency nitrogen plasma source. PR spectra were collected from the QW structures and the energy transitions were obtained. The experimental data of the QW energy transitions were analyzed by theoretical calculations. Using predetermined values such as QW thickness and composition, unknown factors such as the heterojunction band offsets were able to be determined. For the GaN0.02As0.87Sb0.11/GaAs structure, we found that Qc≈0.5. For Ga0.62In0.38N0.026As0.954Sb0.02/GaAs, we found that Qc≈0.8. This value is similar to the antimony free dilute-nitride material GaInNAs since the small amount of antimony does not affect the band offsets. For the technologically important Ga0.61In0.39N0.023As0.957Sb0.02/GaN0.027As0.973/GaAs laser structure, we found that the GaInNAsSb/GaNAs QW had a conduction band offset of 144 meV and a valence band offset of 127 meV. With a greater understanding of the band structure, more advanced GaInNAsSb laser devices can be obtained.