bluuebunny/crossref_metadata_2025_split huggingface dataset:
Iridium Electrodes for Ferroelectric Capacitors Deposited by Liquid-Delivery MOCVD
Authors: Ritterhaus Yves , Hur'yeva Tetyana , Lisker Marco , Burte Edmund Paul 
Published: April 2011

AbstractThin iridium films are required as electrode material for ferroelectric capacitors. SBT or PZT are often used as ferroelectric material in such capacitors. The PZT based non-volatile ferroelectric random access memories show better fatigue characteristics if platinum is replaced by iridium as electrode material. Metalorganic chemical vapor deposition (MOCVD) was used for the deposition because of the superior step coverage on three-dimensional structures compared to the conventional physical vapor deposition processes of metal layers. Particularly, in memory fabrication, good step coverage is essential. The iridium films were deposited on different substrates at temperatures of 300 – 500 °C by liquid-delivery MOCVD. The precursor Ir(EtCp)(1,5COD) [iridium(ethylcyclopentadienyl)(1,5-cyclooctadiene)] was diluted in toluene (0.1 M concentration) for the deposition experiments. The iridium films were deposited onto TiO2/SiO2/Si-, SiO2/Si-, and Si-substrates to compare the iridium film properties on different substrates. The growth conditions like oxygen flow, growth temperature, and reactor pressure were varied. The growth rates were in a range between 0.05 and 4.6 nm per minute. We found that the growth rates were highly influenced by the oxygen flow and the substrate material. Oxygen assisted the decomposition of the precursor, and carbon and hydrogen of the organic source were oxidized, which suppressed its incorporation into the iridium layer. Annealing in an oxidizing ambient at temperatures above 700 °C resulted in an increased oxidation of the films as proved by XRD analyses. The resistivity of the films was determined by the Van-der-Pauw method. Low resistivities of 7 – 70 µΩcm were obtained for the as-deposited iridium films.
Strain Relaxation and Dislocation Confinement in Epitaxial SrTiO3 by Two-Step Growth Technique and the Resulting Dielectric Response
Authors: Yamada Tomoaki , Sherman Vladimir O. , Tagantsev Alexander K. , Su Dong , Muralt Paul , Setter Nava 
Published: April 2011

AbstractA two-step growth technique was used to achieve effective strain relaxation and dislocation confinement of epitaxial SrTiO3(STO) films and through this to improve their microwave dielectric properties. The crystallization of a very thin quasi-amorphous STO layer deposited at a low temperature in the initial growth step enhanced the strain relaxation from the lattice mismatch at the expense of the formation of high density of misfit dislocations. By varying the thickness of the first layer, different strain states of the films were systematically achieved while keeping the total film thickness unchanged. This allowed the study of the effect of strain on permittivity, and showed good agreement with theoretical predictions. Further more, the two-step growth technique suppressed significantly the threading dislocation density in the film, the dislocations being confined to the first layer. This in turn caused reduction in the extrinsic dielectric loss at microwave frequency. The loss reduction was analyzed and explained based on a dielectric composite model.
10 Tbit/inch2 Ferroelectric Data Storage with Offset Voltage Application Method
Authors: Hashimoto Sunao , CHO Yasuo 
Published: April 2011

AbstractFerroelectrics are expected to become one of the next generation ultra-high density data storage media. The requirements for pulse amplitude and the duration to switch the domain were both markedly decreased by using a new domain stabilizing method; offset voltage application method. Additionally, with this method it became possible to invert a smaller domain with a diameter of less than 10 nm. Finally, significant progress was made regarding the memory density for ferroelectric data storage, and an area density of 10.1 Tera-bit/inch2 was successfully achieved. This represents the highest memory density for rewritable data storage reported to date.
Molecular volume and polarizability in the amorphous dielectric Zr0.2Sn0.2Ti0.6O2
Authors: Barron S. C. , van Dover R. B. 
Published: April 2011

AbstractThe dielectric constant of a material is strongly dependent on both the polarizability and the density of the material through the Clausius Mossotti equation. While the atomic polarizability depends on the stoichiometry of the constituent atoms, the molecular polarizability is a function of the atoms’ short range bonding structure and hence can be strongly dependent on processing conditions. Since the density of the material also depends on the thermally activated diffusivity of atoms during processing, varying the processing temperatures has an effect on both the molecular polarizability and the density. The dielectric constant of Zr0.2Sn0.2Ti0.6O2 is shown to be a strong function of the substrate temperature during sputter deposition with the highest value ∼55 at 200 °C and lower values at both higher and lower process temperatures. We have investigated the bonding structure and density of the oxide dielectric deposited at a variety of substrate temperatures in order to elucidate the relative effects of each.
Dislocation-Related Etch Protrusions Formed on 4H-SiC (000-1) Surfaces by Molten KOH Etching
Authors: Gotoh Masahide , Tawara Takeshi , Nakamura Shun-ichi , Tamori Tae , Kuboki Yoshiyuki , Yonezawa Yoshiyuki , Nishiura Masaharu 
Published: April 2011

AbstractIn this study, we investigated surface features formed by molten KOH etching of (000-1) substrates and epilayers, using scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (TEM). We found the surface features formed on (000-1) are protrusions, in contrast to well-known dimples on (0001).
Deep Levels and Compensation in High Purity Semi-Insulating 4H-SiC
Authors: Mitchel William C , Mitchell W. D. , Smith H. E. , Carlos W. E. , Glaser E. R. 
Published: April 2011

AbstractA study of temperature dependent Hall effect (TDH), electron paramagnetic resonance (EPR), photoluminescence (PL) and secondary ion mass spectrometry (SIMS) measurements has been made on high purity semi-insulating (HPSI) 4H-SiC crystals grown by the physical vapor transport technique. Thermal activation energies from TDH varied from a low of 0.55 eV to a high of 1.5 eV. All samples studied showed n-type conduction with the Fermi level in the upper half of the band gap. Carrier concentration measurements indicated the deep levels had to be present in concentrations in the low 1015 cm-3 range. Several defects were detected by EPR including the carbon vacancy and the carbon-silicon divacancy. PL measurements in the near IR showed the presence of the UD-1, UD-2 and UD-3 emission lines that have been found in HPSI material. No correlation between the relative intensities of the PL lines and the TDH activation energies was seen. SIMS measurements on nitrogen, boron and other common impurities indicate nitrogen and boron concentrations higher than those of individual deep levels as determined by TDH or of intrinsic defects as determined by EPR such as the carbon vacancy or the divacancy. It is determined that several different defects with concentrations greater than or equal to 1x1015 cm-3 are required to compensate the residual nitrogen and boron.
Top-down and bottom-up nanofabrication for multipurpose applications.
Authors: Di Fabrizio Enzo , Romanato Filippo , Cabrini Stefano , Deangelis Francesco , Yu Arum Amy , Barsotti Rober , Dealla Giustina Gioia , Brusatin Giovanna , Stellacci Fracesco 
Published: April 2011

AbstractIn this article we will show three recent examples of combined strategies aiming at merging top-down and bottom-up approach for nanofabrication at nanoscale level. The first example shows the fabrication of nanogaps performed by Focus Ion Beam technique that have been used to measure the conductivity of few gold nanoparticles aggregates deposited by Dip Pen lithography. The second example deals with the parallel replica of high resolution master generated by Electron Beam lithography by means of an innovative lithographic process based on DNA supramolecular nano-stamping. The latter example proposes the possibility to generate, through radiation exposure, direct patterning of hybrid sol gel material doped with fluorescent molecules. The outline of the fabrication approaches and their scientific and technical perspective are discussed.
Influence of Low Molecular Weight PDMS Chains in PDMS-based Non-Photolithography
Authors: Kim Jinook , Lee C. H. , Park Mikyung , Chae G. S. , Chung In-Jae 
Published: April 2011

AbstractWe describe that an elastomeric stamp of poly(dimethylsiloxane) (PDMS) can modify the surface energy of some surfaces when brought into conformal contact with the number of stamping. We focus on an increase of the hydrophobicity of the patterned surface due to diffusion of low molecular weight (LMW) silicone polymer chains. The transfer of PDMS to the surface during patterning is relevant to and calls for attention by those who are using this method in applications where control of the surface chemistry is of importance for the application.
Using Self-assembly and Selective Chemical Vapor Deposition for Precise Positioning of Individual Germanium Nanoparticles on Hafnia
Authors: Coffee Shawn S , Winkenwerder Wyatt A , Stanley Scott K , Davood Shahrjerdi , Banerjee Sanjay K , Ekerdt John G 
Published: April 2011

AbstractGermanium nanoparticle nucleation was studied in organized arrays on HfO2 using a SiO2 thin film mask with ~20-24 nm pores and a 6×1010 cm-2 pore density. Poly(styrene-b-methyl methacrylate) diblock copolymer was employed to pattern the SiO2 film. Hot wire chemical vapor deposition produced Ge nanoparticles using 4-19 monolayer Ge exposures. By seeding adatoms on HfO2 at room temperature before growth and varying growth temperatures between 725-800 K, nanoparticle size was demonstrated to be limited by Ge etching of SiO2 pore walls.
Radiation Shielding Analysis for Various Materials in the Extreme Jovian Environment
Authors: Atwell William 
Published: April 2011

ABSTRACTEarlier particle experiments in the 1970s on Pioneer-10 and -11 and Voyager-1 and -2 provided Jupiter flyby particle data, which were used by Divine and Garrett to develop the first Jupiter trapped radiation environment model. This model was used to establish a baseline radiation effects design limit for the Galileo onboard electronics. Recently, Garrett et al. have developed an updated Galileo Interim Radiation Environment (GIRE) model based on Galileo electron data. In this paper, the GIRE model was utilized to generate trapped proton and electron spectra as a function of Rj (Rj = radius of Jupiter = ∼71,400 km). Using these spectra and a high-energy particle transport codes (MCNPX and HZETRN), radiation exposures and dose effects for a variety of shielding materials (Al, polyethylene [PE], and Ta plus several other elemental materials for “Graded-Z” portion of the paper) and thicknesses are presented for the Icy Moon, Europa, Ganymede, and Callisto for several orbital inclinations. In addition, an in-depth discussion and absorbed dose calculations are presented for “Graded-Z” materials and several computer codes were utilized for comparison purposes. We find overall there is generally quite good agreement between the various computer codes utilized in the study: MCNPX (Monte Carlo) vs. HZETRN (deterministic) for slab shielding and the comparison of “Graded-Z” shielding using the CEPXS, NOVICE, and NASA JPL codes. Finally, we conclude that the merits of using “Graded-Z” materials that include PE, due to cost and weight, should aid future Jupiter mission planners and spacecraft designers.
Sol-Gel Synthesis of Thick Ta2O5 Films for Photonic Band Gap Materials
Authors: Ndiege Nicholas , Wilhoite Tabitha , Subramanian Vaidyanathan , Shannon Mark , Masel Rich 
Published: April 2011

ABSTRACTAdvances in microelectromechanical systems has generated an ever growing demand for novel insulating material applicable to high temperature systems. Photonic bandgap materials are appealing for such applications, specifically Ta2O5 due to its high index of refraction, refractory nature and negligible absorbance in the infrared region. The challenge faced in the realization of such materials is the synthesis of crack free Ta2O5 films whose thickness is in the order of a quarter wavelength of the incident infrared radiation.This work seeks to investigate the effect of addition of polyvinyl pyrollidone (PVP) as a binder material in the sol gel synthesis of thick, uniform and crack free Ta2O5 films. Incorporation of PVP into the sol precursor has enabled uniform and crack free films with thicknesses of up to 2.4 microns to be realized. Chemical probing of the precursor was conducted via TGA, FTIR, and NMR analysis of the sol to elucidate the processes behind this film formation. The calcined oxide films were characterized via SEM, XRD and XPS.
Direct immobilization of DNA on partially functionalized diamond surface
Authors: Yang Jung-Hoon , Song Kwang-Soup , Kuga Shouma , Kawarada Hiroshi 
Published: April 2011

ABSTRACTAmino groups were functionalized directly on the diamond surface after treating oxidation and fluorination for detection of DNAs, respectively. For simple process, immobilization of probe DNAs was carried out directly on the partially aminated diamond without linker molecules. After fabricating micropatterned diamond, specific hybridization with Cy-5 labeled target DNA at a concentration of 100 nM could be clearly detected on H-terminated, partially O-terminated, and partially F-terminated diamonds, respectively. The hybridization intensities determined by epifluorescence microscopy were compared and analyzed.
Photochemical Micro-pattern Substitution of Functional Groups for Protein Attachment Control
Authors: Murahara Masataka , Sato Yuji 
Published: April 2011

ABSTRACTHydrophilic and hydrophobic groups were selectively incorporated on the poly(methyl methacrylate) [PMMA] surface using a Xe2 excimer lamp and ArF excimer laser. With this new technique, a protein adsorption on the PMMA surface can be controlled.PMMA was firstly irradiated with a Xe2 excimer lamp in the presence of perfluoropolyether [PFPE] liquid layer to incorporate CF3 groups, and secondly, the PMMA surface was irradiated by an ArF excimer laser through a patterned reticle in the presence of water to incorporate OH groups or NH2 groups in an ammonia gas ambience. The area ratio of hydrophilic and hydrophobic of the modifying sample was made to 1:3, 1:1, and 3:1. The results showed that the fibrin absorption on the sample with hydrophilic and hydrophobic micro domains depended on the area ratio of the hydrophilic and hydrophobic. The absorption coefficient of the amide band remarkably decreased with increase in water contact angle. Furthermore, it was confirmed that the absorption coefficient of fibrin decreased as the interval of CF3 and OH or NH2 groups was narrowed from 250 to 20 μm, and the fibrin sticking on the modified surface with the 20 μm hydrophilic and hydrophobic micro domains was reduced to one-twenty of that on the untreated sample.
Creating conjugated hydrogel encapsulated membranes
Authors: Jeon Tae-Joon , Malmstadt Noah , Schmidt Jacob 
Published: April 2011

ABSTRACTDevice engineering for ion channel proteins requires developing systems that incorporate mechanically stable, long-lived lipid bilayer membranes. Building on our previous work, we have further increased lipid bilayer longevity through covalent conjugation of lipid molecules in the bilayer to an encapsulating hydrogel. This is accomplished by polymerizing the hydrogel in situ around a gigaohm-seal membrane containing vinyl-modified lipid head groups, forming a conjugated hydrogel encapsulated membrane (cgHEM). Membranes formed in this manner show remarkable stability, maintaining gigaohm-level resistance for over 270 hours, better than an order-of-magnitude improvement over the previous state of the art. They also demonstrate the capacity to support the incorporation and measurement of ion channel proteins at the single-molecule level.
Effect of Substrate Surface Modification on Biomineralization of Osteoblasts
Authors: Meng Yizhi , Ba Xiaolan , Kwak Seo-Young , DiMasi Elaine , Ruppel Meghan , Miller Lisa , Ge Shouren , Pernodet Nadine , Rafailovich Miriam , Qin Yi-Xian 
Published: April 2011

ABSTRACTUnderstanding how biomineralization occurs in the extracellular matrix (ECM) of bone cells is crucial to the development of a successfully engineered bone tissue scaffold, and to date there has not been a well-established method for the quantitative examination of bone mineralization in situ. We investigated the mechanical properties of MC3T3-E1 osteoblast-like cells and the crystalline properties of their biomineralized ECM in vitro using shear modulation force microscopy (SMFM), confocal laser scanning microscopy (CLSM), synchrotron X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The elastic modulus of the mineralizing cells increased at time points corresponding to mineral production, whereas that of the non-mineralizing cells did not vary significantly over time. CLSM showed a restructuring of the F-actin fiber network of mineralizing cells with time, which indicates remodeling activities in the cytoskeleton and was not seen in the non-mineralizing cells. Both XRD and FTIR showed that the mineralizing subclone produced hydroxyapatite in situ and that the non-mineralizing subclone was in fact weakly biomineralizing.
Control of Enzymatic Activities by Magnetite Nanoparticles
Authors: Zhou Hui , Aubin-Tam Marie-Eve , Hamad-Schifferli Kimberly 
Published: April 2011

ABSTRACTEnzymes are proteins that catalyze chemical reactions, participating in almost all processes in the cell to achieve significant reaction rates and serving a wide variety of functions inside living organisms. Here, we intended to control enzymatic activities by applying external radio frequency magnetic field (RFMF) through nanosized antenna. Ribonuclease A (RNase A), which is a relative small protein that cleave single-stranded RNA, was conjugated to magnetite nanoparticles (NP) by non-covalent interaction. The diameters of Fe3O4 nanoparticles are less than 10nm. External RFMF was applied, and the enzymatic activities of RNase A were tuned at different levels by varying the frequencies and incubation times. Comparison results by using water bath were also presented.
Strained Si-based Nanomembrane Materials
Authors: Scott Shelley A. , Roberts Michelle M. , Savage Donald E. , Lagally Max G. 
Published: April 2011

ABSTRACTApplication of tensile strain to the Si(100) lattice is known to enhance carrier mobility in field effect transistors through modification of the Si band structure. Si is conventionally placed under tensile strain using methods such as Si3N4 capping for strained channel devices, and epitaxial growth of Si on a strain graded SiGe substrate for large area strain. The latter case preserves and propagates threading dislocations, and both cases require use of a bulk rigid substrate, which prohibits the use of strained Si in applications such as flexible electronics, or indeed in any application where strained Si is desirable on a non-epitaxial substrate. Elastically strained, single-crystal, Si-based nanomembranes, in which the release of a Si/SiGe/Si heterostructure from its growth substrate allows elastic strain sharing between the layers, circumvent these issues. These nanomembranes are extremely flexible, virtually dislocation-free, and transferable to almost any other surface.
Pronounced Photonic Effects of High-Pressure Water Vapor Annealing on Nanocrystalline Porous Silicon
Authors: Gelloz Bernard , Shibata Takayuki , Mentek Romain , Koshida Nobuyoshi 
Published: April 2011

ABSTRACTThe effects of high-pressure water vapor annealing (HWA) on the refractive index of PS have been studied. HWA was conducted at 260 °C and 1.3 MPa, for 3 h. The refractive index (real partnand imaginary partk) was estimated by fitting reflectivity spectra. HWA considerably modifies the layers refractive index. It enhances the optical transparency of PS, particularly at short wavelengths down to below 400 nm. Both n and k are significantly reduced by HWA between 400 nm and 850 nm. These results are attributed to the high level of oxidation of PS after HWA. The high transparency of the treated layers enables Si-based photonics in the full visible range and also in the near UV range. Distributed Bragg reflectors (DBRs) have been fabricated. The central wavelengths appear blue-shifted compared to untreated samples due to the reduced refractive index. Almost no changes could be found in the reflectivity properties after one year storage in air for HWA-treated DBRs. Therefore, HWA is very useful for getting stable practical photonics devices in the visible and near UV range.
Mechanical properties of Ge/Si core-shell nanowires under a uniaxial tension
Authors: Yano Y. , Nakajima T. , Shintani K. 
Published: April 2011

ABSTRACTThe mechanical properties of Si/Ge core-shell nanowires under a unixial tension are studied using molecular-dynamics simulation. The effects of anisotropy and the fraction of the core atoms on the Young's moduli of the core-shell nanowires are examined. The values of their Young's moduli deviate from those calculated using Vegard's law. Single atom chains are formed at the final stages of elongation of the nanowires.
Optical Properties of Si and Ge/Si Nanocrystals in Silicon Oxide Matrix
Authors: Uekusa Shin-ichiro , Kushida Atsuhiko 
Published: April 2011

ABSTRACTThe contribution of oxide-related emission in Photoluminescence (PL) spectra from Ge and Si nanocrystals mixture embedded in silicon oxide (Ge/Si-SiO2) and Si nanocrystals embedded in silicon oxide (Si-SiO2) thin film prepared by RF-magnetron co-sputtering method is investigated. All as-deposited thin films were annealed for 1 hour in the temperature range from 300 to 1100 °C in an Ar atmosphere. The samples were evaluated by using PL, Energy dispersive spectroscopy (EDX), Raman scattering and X-ray photoelectron spectroscopy (XPS) measurements. All the measurements were performed at room temperature. The maximum PL intensity of Ge+Si-SiO2 mixture thin film has increased more than the Si-SiO2 thin film by approximately 10 times. From the results of Raman scattering and XPS measurements, it is consider that the oxygen defect centers in the host material SiO2 increased by the diffusion of Ge. An increase in the PL intensity of Ge+Si-SiO2 mixture thin film is systematically discussed.
Modeling the Capacitance-Voltage Characteristics of Organic Schottky Diode in the Forward Bias
Authors: Chiang Ko-Yu , Tseng Huai-Yuan , Lin Chang-Yu , Kung Chen-Pang , Hou Wei-Hsin 
Published: April 2011

ABSTRACTIn this work, an accurate capacitance-voltage (C-V) model of organic Schottky diode is proposed. By taking the interface trap of the Schottky barrier into account, the capacitance model was derived from the junction and interface capacitance as a function of operation voltage. The model successfully describes the turn-around capacitance characteristic of Al/poly(3-hexylphiophene)(P3HT)/poly(3,4-ethylenedioxythiophene)poly(styrene sulfonate)(PEDOT:PSS)/IZO Schottky diode in the forward bias region. The simulated capacitances are in good agreement with our experimental data.