bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and Electrochemical Characterization of DNA-modified Nanocrystalline Diamond Films
Authors: Yang Wensha , Auciello Orlando , Butler James E. , Cai Wei , Carlisle John A. , Gerbi Jennifer E. , Gruen Dieter M. , Knickerbocker Tanya , Lasseter Tami L. , Russell John N. , Smith Lloyd M. , Hamers Robert J. 
Published: June 2019

ABSTRACTNanocrystalline diamond thin films of sub-micron thickness have been covalently modified with DNA oligonucleotides. Quantitative studies of hybridization of surface-bound oligonucleotides with fluorescently tagged complementary and non-complementary oligonucleotides were performed. The results show no detectable nonspecific adsorption, with extremely good selectivity between matched and mismatched sequences. Impedance spectroscopy measurements were made of DNA-modified boron-doped nanocrystalline diamond films. The results show that exposure to non-complementary sequences induce only small changes in impedance, while complementary DNA sequences produce a pronounced decrease in impedance. The combination of high stability, selectivity, and the ability to directly detect DNA hybridization via electrical means suggest that diamond may be an ideal substrate for continuously-monitoring biological sensors.
Influence of Indium Incorporation on Recombination Dynamics in AlInGaN Layers Grown by Pulsed Metal Organic Chemical Vapor Deposition
Authors: Song Jae Ho , Lee Jhang W. , Yu P.W. , Ryu Mee-Yi , Zhang J. , Kuokstis E. , Yang J. W. , Khan M. Asif 
Published: June 2019

AbstractWe investigated the recombination dynamics of the AlInGaN grown by a pulsed metal organic chemical vapor deposition (PMOCVD) by using the temperature dependent photoluminescence (PL) and time resolved photoluminescence (TRPL). The indium mole fractions of our samples are 0-3% and the PL measurement temperatures are 10-300K. The PL data show that AlInGaN layers with higher indium ratios exhibit significantly stronger PL intensities and less intensity reduction to the temperature increase. The TRPL data show that higher indium layers yield shorter lifetime in the low temperature range and longer lifetime in the high temperature range. These results indicate that the indium contents into the AlInGaN layers generate more localized states, which are likely to make the recombination processes in the AlInGaN layers less sensitive to the variation of the temperature.
Self-assembled InP Quantum Dot -TiO2 Solid Grätzel Solar Cell
Authors: Zeng Tingying , Gladwin Elizabeth , Claus Richard O. 
Published: June 2019

AbstractThe processing of Solid Grätzel Solar Cells (SGSCs) offers advantages of cost effective fabrication, possible flexible products, and high incident photon-to-electron conversion efficiencies (IPCE). In this paper, InP quantum dots (QDs) were synthesized and used as the photosensitizer to design new generation SGSCs. An organic p-type charge transport material (spiro-OMeTAD) was used as the hole-transport material (HTM). The InP QD has an average diameter of approximately 3nm. Preliminary research indicates that InP QD is a promising photosensitizer, which allows the sensitized SGSC TiO2 nanocrystalline cell to achieve over 400mV open circuit photovoltage, and a short-circuit current greater than 0.035mA/cm2 under the illumination of a solar simulator with an integrated light power of 58mW/cm2.
Barrier Material Improvement in AlGaN/GaN Microwave Transistors Under Gamma Irradiation Treatment
Authors: Vitusevich S.A. , Petrychuk M.V. , Klein N. , Danylyuk S.V. , Belyaev A.E. , Konakova R.V. , Avksentyev A. Yu. , Kurakin A.M. , Lytvyn P.M. , Danilchenko B.A. , Tilak V. , Smart J. , Vertiatchikh A. , Eastman L.F. 
Published: June 2019

AbstractEffect of small dose gamma-irradiation on electrical characteristics of AlGaN/GaN high electron mobility transistors has been investigated. Decreasing of the leakage current and its noise has been registered after dose of 1×106 Rad. As-grown heterostructures used in further for the device fabrication have been examined after the same radiation treatment. The small dose radiation results are explained within a model that takes into account relaxation of elastic strains and structural-impurity ordering occurring in the barrier layer under irradiation.
Structural and Optical Properties of InGaN/GaN Multi-Quantum Well Structures with Different Indium Compositions
Authors: Kim Chang-Soo , Noh Sam-Kyu , Lee Kyuhan , Kim Sunwoon , Song Jay P. 
Published: June 2019

AbstractThe structural and optical properties of InGaN/GaN multiple quantum wells (MQWs) grown on sapphire by MOCVD have been investigated using high-resolution XRD, PL and TEM. The samples consisted of 10 periods of InGaN wells with 6.5nm thickness. The designed indium compositions were 15, 20, 25 and 30% (samples C15, C20, C25, C30, respectively). The thickness of GaN barrier was 7.5nm. The MQW in sample C15 maintained lattice coherency with the GaN epilayer underneath, the MQWs in the other samples, however, experienced lattice relaxation. The crystallinity of the samples decreased considerably with In concentration. As In composition increased, PL peak energy showed a red-shift, and the FWHM of the peaks increased. The increase in the FWHM is attributed to the defects due to the lattice relaxation. For C25 the PL peak intensity increased sharply in spite of the defects due to the lattice relaxation of the sample. It is concluded that the results are related to the In-rich region due to indium phase separation which was observed by TEM image.
Photoinduced Low Refractive Index Patterning in a Photosensitive Hybrid Material
Authors: Park Jang-Ung , Kang Eun-Seok , Bae Byeong-Soo 
Published: June 2019

AbstractLight illumination processing created photoinduced reduction of refractive index as well as volume contraction in an organic-inorganic hybrid material. Whereas both refractive index and film thickness are decreased significantly by the light exposure, transmittance and anti-soiling property of the hybrid film are not affected by the exposure. Direct patterning is possible upon light illumination using the photoinduced change in thickness without any developing process.
Investigation of the Effect of Uv-Assisted Oxidation and Nitridation of Hafnium Metal Films
Authors: Essary C. , Craciun V. , Howard J. M. , Singh R. K. 
Published: June 2019

AbstractHf metal thin films were deposited on Si substrates using a pulsed laser deposition technique in vacuum and in ammonia ambients. The films were then oxidized at 400 °C in 300 Torr of O2. Half the samples were oxidized in the presence of ultraviolet (UV) radiation from a Hg lamp array. X-ray photoelectron spectroscopy, atomic force microscopy, and grazing angle X-ray diffraction were used to compare the crystallinity, roughness, and composition of the films. It has been found that UV radiation causes roughening of the films and also promotes crystallization at lower temperatures.Furthermore, increased silicon oxidation at the interface was noted with the UVirradiated samples and was shown to be in the form of a mixed layer using angle-resolved X-ray photoelectron spectroscopy. Incorporation of nitrogen into the film reduces the oxidation of the silicon interface.
An Approach for Evaluating the General and Localised Corrosion of Carbon-Steel Containers for Nuclear Waste Disposal
Authors: Marsh G.P. , Taylor K.J. , Shrland S.M. , Tasker P.W. 
Published: June 2019

AbstractThe paper considers the long term corrosion of carbon-steel containers for heat generating nuclear waste in a granitic repository. Under such conditions carbon steel may exhibit general, localised or passive corrosion behaviour depending on the exact composition and redox potential of the groundwater contacting the containers; localised corrosion being of most concern because it has the fastest propagation rate. It is well established, however, that such localised corrosion is only possible when the environment is sufficiently oxidising to maintain a positive potential gradient between the cathodic surface and the corrosion sites, which requires that species with oxidising potentials greater than water need to be present. This fact provides a basis for estimating the periods during which containers may be subject to localised and subsequently to general corrosion, and hence for making an overall assessment of the metal allowance required for a specified container life. A model for the diffusion transport of oxygen has been developed, and a sensitivity analysis has shown that the period of possible localised attack is strongly dependent on the passive film leakage current, the radiation dose rate and the oxygen diffusion coefficient.
Natural Analogues: Their Application to the Prediction of the Long-Term Behavior of Nuclear Waste Forms
Authors: Ewing Rodney C. , Jercinovic Michael J. 
Published: June 2019

AbstractOne of the unique and scientifically most difficult aspects of nuclear waste isolation is the extrapolation ofshot-term laboratory data (hours to years) to the long time periods (103-105 years) required by regulatory agencies for performance assessment. The direct verification of these extrapolations is not possible, but methods must be developed to demonstrate compliance with government regulations and to satisfy the lay public that there is a demonstrable and reasonable basis for accepting the long-term extrapolations. Natural analogues of both the repository environment (e.g. radionuclide migration at Oklo) and nuclear waste form behavior (e.g. alteration of basaltic glasses and radiation damage in minerals) have been used to demonstrate the long-term behavior of large scale geologic systems and, on a smaller scale, waste form durability. This paper reviews the use of natural analogues to predict the long-term behavior of nuclear waste form glasses. Particular emphasis is placed on the inherent limitations of any conclusions that are based on “proof” by analogy. An example -- corrosion of borosilicate glass -- is discussed in detail with specific attention to the proper and successful use of natural analogues (basaltic glass) in understanding the long-term corrosion behavior of borosilicate glass.
The Transport of Uranium and Technetium Through The unsaturated Tuffs, Yucca Mountain, Nevada
Authors: Cederberg Gail A. , Greenwade L. Eric , Travis Bryan J. 
Published: June 2019

AbstractAn area containing unsaturated fractured tuffs at Yucca Mountain, Nevada, is one of the potential sites for geologic storage of high-level radioactive waste. The Environmental Protection Agency (EPA) 40 CFR 191 Regulation limits the cumulative releases of many radionuclides from the repository to the accessible environment for 10,000 years after disposal [I]. Numerical models can be used to determine if the EPA containment requirement is met.In this paper a preliminary set of transport calculations for uranium and technetium is discussed. First, a foundation for the calculations, a comprehensive, referenced geochemical/geophysical model containing the current stratigraphic, petrologic, hydrogeologic, geochemical, and material data for the Yucca Mountain site was compiled. Second, the integrated transport of uranium and technetium from the repository to the water table was modeled. An expected-case flow scenario and a worse-case flow scenario were used in the calculations. The sorption of technetium was neglected in the worse-case scenario. Results show that in the case of uranium, the estimated transport was only moderately sensitive to the magnitude of the flow because sorption had a significant effect on the retardation. In the case of technetium, when sorption was neglected, the flow dominated the transport. The EPA contain- ment requirements were met for all cases. These preliminary calculations will be used as a basis to investigate the effects of physical and geochemi- cal processes on the long-term transport of radionuclides at Yucca Mountain.
Humic Colloid Generation of Transuranic Elements in Groundwater and Their Migration Behaviour
Authors: Kim J.I. , Buckau G. , Zhuang W. 
Published: June 2019

AbstractThe generation of humic colloids of Am(III) has been investigated in Gorleben groundwaters containing different amounts of humic substances. Dissolved organic carbon (DOC) in these groundwaters consists mainly of humic acid and fulvic acid, which is present in a colloidal form through aggregation with trace heavy metal ions of groundwater constituents. Concentrations of these heavy metal ions are proportional to the DOC concentration. The generation of Am(III) pseudocolloids through geochemical interactions with humic colloids in different groundwaters is quantified by ultrafiltration as well as ultracentrifugation by the aid of radiometric concentration measurements. The speciation of dissolved Am(III) species in groundwaters is carried out by laser induced photoacoustic spectroscopy (LPAS).
Passive Layer Formation at Ferroelectric PbTiO3/Pt Interfaces Studied by EELS
Authors: Welz S. J. , Fu L. F. , Erni R. , Kurasawa M. , McIntyre P. C. , Browning N. D. 
Published: June 2019

AbstractPolarization fatigue with repeated electric cycles in ferroelectric thin films is a major degradation problem in ferroelectric nonvolatile memories. However, the origin of this phenomenon is still not properly understood. The fatigue mechanism of a ferroelectric perovskite in a multilayer ferroelectric PbTiO3 thin film material has been investigated here using scanning transmission electron microscopy (STEM). Z-contrast images of the interfaces show that the ferroelectric PbTiO3 layer has partly decomposed into a single crystal PbTiO3 layer and an amorphous layer. Nanometer-sized precipitates are present near the Pt electrode. Electron energy-loss spectroscopy (EELS) analysis reveals that the amorphous layer is a Ti-rich phase between TiO2 and PbTiO3. The precipitates are determined to be a Pt-Pb rich crystalline phase. It is suggested that the formation of the structure-distorted intermediate layer and precipitates may be associated with the ferroelectric degradation process by acting as a passive layer in a ferroelectric capacitor. In addition, the formation of the Pt-Pb rich precipitates may cause an interruption of the consistent Pt electrode, which may result in failure of the device.
Kinetic analysis and correlation with residual stress of the Ni/Si system in thin film
Authors: Cacho F. , Aime D. , Wacquant F. , Froment B. , Rivero C. , Gergaud P. , Thomas O. , Cailletaud G. , Jaouen H. , Minoret S. , Souifi A. 
Published: June 2019

AbstractReactive diffusion of the Ni/Si system has been studied by annealing nickel thin film on (100) silicon crystal. The measurement of the NiSi sheet resistance as a function of the annealing temperature and the type of annealing (Rapid Thermal Annealing and spike one) has been investigated. A kinetic model based on multiphase diffusion has been developed that fits experimental sheet resistance data. Residual stress in the thin film, measured by a curvature measurement technique, is correlated with the nature of the phases in the film. Finally the viscoplastic mechanical behavior of the Ni2Si and NiSi phases is analyzed in the case of low and fast thermal ramps.
Comparison Between In-situ Annealing and External Annealing For Barium Ferrite Thin Films Made by RF Magnetron Sputtering
Authors: Abuzir A. R. , Yeh W. J. 
Published: June 2019

AbstractDue to their large magnetic anisotropy perpendicular to the film plane, barium ferrite thick films (BaFe12O19, or BaM) with c-axis orientation are attractive candidates for microwave applications [1,2]. Barium ferrite thin films on silicon substrates without under layer have been deposited under various conditions by RF magnetron sputtering. The structure of the as-grown films is amorphous. External annealing in air has been done at 950°C for ten minutes to crystallize the films. C-axis oriented thin films with squareness of about 0.87 and coercivity of about 3.8KOe are obtained.Thick BaM films with c-axis orientation are difficult to achieve with one single deposition. Multilayer technique looks promising to grow thick films [3]. The external annealing process is difficult to incorporate with the multilayer procedure. An in-situ annealing procedure has been developed to obtain films, which can be used as the basic component for future multilayer deposition. Barium ferrites are first magnetron sputtered on bare silicon substrates in Ar + O2 atmosphere at substrate temperature of 500-600°C, the deposition pressure was kept about 0.008 torr. After the deposition, the temperature of the substrate is immediately increased to about 860°C for ten minutes in 140 torr of argon (80%) and oxygen (20%) mixture of gas, which was introduced into the chamber without breaking the vacuum. With the in-situ process, c-axis oriented thin films of 0.88 squareness and coercivity value of about 4.3KOe are obtained.Both annealing methods seem to have the similar effect on the perpendicular squareness and coercivity at various film thicknesses. The average value of the saturation magnetization Ms obtained from the in-situ annealing using multilayer technique is higher than that of the external one. We have grown films up to 1.0 micron thickness using the multilayer technique, in which three layers of 0.3 μm thickness each are deposited until the final thickness is reached. After the deposition of each layer, it was in-situ annealed before starting the deposition of the next layer. With the multilayer technique, coercivity of about 3.5 KOe and average value of the saturation magnetization Ms of about 4.0 K Gauss is obtained.
Fabrication and Composition Control of NiTi Shape Memory Thin Films for Microactuators
Authors: Getchel David J. , Savage Richard N. 
Published: June 2019

AbstractMicroactuators fabricated with NiTi thin films take advantage of the shape memory effect's large energy density (∼5-10 joules/cm3) and high strain recovery (∼8%). Microelectromechanical Systems (MEMS) designed with these actuators can serve as biosensors, micro-fluidic pumps or optical switches. However, the fundamental mechanical properties of these shape memory NiTi films have not been fully characterized with micro-scale test structures. Equiatomic NiTi thin films were deposited by co-sputtering NiTi and Ti targets with the intension of fabricating such test structures. Dual cathodes allowed direct control of the film composition by adjusting the Ti cathode power. Energy Dispersive Spectroscopy (EDS) quantified the film composition relative to pure standards. A thin (∼50 nm) chromium film on a pure silicon substrate created excellent film adhesion. Oxidized Si wafers did not bond with the Cr and NiTi films. This deposition method enabled control of film composition and the necessary adhesion.
Investigation of local stress fields: Finite element modelling and High Resolution X-Ray Diffraction
Authors: Loubens A. , Rivero C. , Boivin Ph. , Charlet B. , Fortunier R. , Thomas O. 
Published: June 2019

AbstractThe influence of local stress fields on the electrical properties of Si-based nanostructures is of increasing concern. The experimental evaluation of stresses at the required scale (few nanometres) remains, however, a very challenging task. We propose a non destructive X-ray diffraction technique for local strain measurements using a laboratory radiation source. This technique provides an alternative route to micro diffraction experiments. High resolution X-ray diffraction is used to analyse the diffraction from the periodic strain field induced in silicon by a periodic array. We analyzed arrays of Si3N4 lines (thickness: 149 nm, width: 145 nm, pitch: 169 nm) on silicon, and arrays of single crystal Si lines (period: 0.6 micrometers, width: period/2, thickness: 50 nm) etched in SOI (Silicon On Insulator) and capped with SiO2 and Si3N4. Reciprocal space maps were performed around the Si substrate diffraction lines. A Bartels 4 reflections Ge 220 monochromator was used in combination with a 3 reflections Ge 220 analyser. X ray diffraction rocking curves performed on Si 004 and Si 224 reveal distinct superlattice peaks whose spacing is related to the in-plane periodicity. Reciprocal space maps reveal particular intensity distributions caused by the stress gradient in the transverse and perpendicular directions of the lines. Reciprocal space maps obtained by High Resolution X-Ray Diffraction are compared with maps calculated from displacement fields derived from finite element modeling. Very clear superlattice peaks are, however, observed around the bulk Silicon substrate reciprocal lattice nodes, which indicates a great sensitivity of this method to elastic stresses. The influence of the lines aspect ratio on the reciprocal space maps has been studied both experimentally and through modelling.
In-Situ TEM Study of Plastic Stress Relaxation Mechanisms and Interface Effects in Metallic Films
Authors: Legros Marc , Dehm Gerhard , Balk T. John 
Published: June 2019

AbstractTo investigate the origin of the high strength of thin films, in-situ cross-sectional TEM deformation experiments have been performed on several metallic films attached to rigid substrates. Thermal cycles, comparable to those performed using laser reflectometry, were applied to thin foils inside the TEM and dislocation motion was recorded dynamically on video. These observations can be directly compared to the current models of dislocation hardening in thin films. As expected, the role of interfaces is crucial, but, depending on their nature, they can attract or repel dislocations. When the film/interface holds off dislocations, experimental values of film stress match those predicted by the Nix-Freund model. In contrast, the attracting case leads to higher stresses that are not explained by this model. Two possible hardening scenarios are explored here. The first one assumes that the dislocation/interface attraction reduces dislocation mobility and thus increases the yield stress of the film. The second one focuses on the lack of dislocation nucleation processes in the case of attracting interfaces, even though a few sources have been observed in-situ.
Near-Infrared Photodetection with Molecular Beam Epitaxy Grown Extended InGaAs
Authors: Fu Jun-Xian , Yu Xiaojun , Kuo Yu-Hsuan , Harris James S 
Published: June 2019

AbstractStrain-balanced InxGa1-xAs/InyGa1-yAs superlattices and fractional monolayer In0.532Ga0.468As/InAs superlattices were grown by solid-source molecular beam epitaxy (SSMBE) in order to extend the photodetection wavelength range beyond 1.7μm. Material qualities were characterized by transmitted electron microscope (TEM), X-ray diffraction (XRD), roomtemperature photoluminesecence (RTPL) and optical absorption measurement.