bluuebunny/crossref_metadata_2025_split huggingface dataset:
First-Principles Modeling for Current-Voltage Characteristics of Resistive Random Access Memories
Authors: Miyazaki Takehide , Nakamura Hisao , Nishio Kengo , Shima Hisashi , Akinaga Hiroyuki , Asai Yoshihiro 
Published: December 2013

ABSTRACTWe present results of first-principles non-equilibrium Green’s function calculations for current-voltage (IV) characteristics of the electrode/HfO2/electrode model systems. In order to investigate the effect of the electrode materials on the IV characteristics, we considered two transition metals for electrode, Ta and W, which are both body-centered-cubic elemental metals but have different valence numbers. We simulated the ON state by placing oxygen vacancies in the HfO2 layer while the OFF state was modeled with HfO2 without oxygen vacancies. At the OFF state, no electric current flowed for -1 V up to +1 V, as expected. At the ON state, however, we found that the absolute current for the Ta electrode was twice as large as that for the W electrode. The analysis of the IV characteristics shows that the electronic coupling between Ta and HfO2 is substantially stronger than that between W and HfO2. Our study demonstrates the importance of the matching between electrode and insulator materials to achieve a high ON- to OFF-current ratio in ReRAMs at a low bias.
Mechanics of quasi-1D ZnO nanostructures for energy harvesting
Authors: Rinaldi Antonio , Araneo Rodolfo , Pea Marialilia , Notargiacomo Andrea 
Published: December 2013

ABSTRACTThe mechanical properties of ZnO nanowires are the “enabling factor” for piezotronic nanogenerators. Examining the size effects entail the determination of both elastic (i.e. the Young’s Modulus, E) and failure strength (e.g. fracture, fatigue, buckling, etc.) properties of ZnO nanostructures for nanogenerators. An investigation directed to both types of effects is presented here for the first time. On one hand the strength size effects are pointed out and discussed in the framework of a generalized Weibull framework that is set forward for ZnO NWs. On the other hand, the implications of the size effects on elasticity properties are discussed and quantified using numerical simulations. The results demonstrate that the stiffening of smaller NWs can adversely affect the performance in a non-negligible manner, suggesting that both mechanical size-effects have to be considered for design purposes.
The Microstructure and Local Piezoelectric Response in Polymer Nanocomposites with Different Ferroelectric Crystalline Additions
Authors: Kiselev Dmitry A. , Malinkovich Mikhail D. , Parkhomenko Yuriy N. , Solnyshkin Alexandr V. , Bogomolov Alexey A. , Silibin Maxim V. , Gavrilov Sergei A. , Shvartsman Vladimir V. , Lupascu Doru C. 
Published: December 2013

ABSTRACTIn this work, we report on local ferroelectric and piezoelectric properties of nanostructured polymer composites P(VDF-TrFE)+x(Ba,Pb)(Zr,Ti)O3 (x = 0 - 50 %). High-resolution imaging of ferroelectric domains, local polarization switching, and polarization relaxation dynamics were studied by piezoresponse force microscopy. In particular, we found that (Ba,Pb)(Zr,Ti)O3 inclusions usually show a strong unipolar piezoresponse signal, as compared to the polymer matrix. By scanning under high dc voltage the films can be polarized uniformly under both positive and negative electric fields. Stability of the polarized state is discussed.
Ab initio studies of the structure and the interaction of cellulose IIII crystal
Authors: Ueda Kazuyoshi , Ishikawa Tetsuya , Miyamoto Hitomi , Hayakawa Daichi 
Published: December 2013

ABSTRACTCellulose is one of the most abundant renewable resources and has high potential for the use as a future energy and materials for the chemical industries. We have investigated the crystal structure of cellulose IIII by using first principle density functional theory (DFT) calculation. The geometry optimization was performed with variable-cell relaxation with the Quantum ESPRESSO program package. We used Perdew-Burke-Ernzerhof (PBE) functional and compared the results with long-range van der Waals type correction term approach (PBE-D). The results are in good agreement with the experimentally obtained crystal structure of cellulose IIII when we used the PBE-D. Although the calculated cell parameters were slightly smaller than the experimental one, it can be well explained to include the thermal expansion effect in the experimental condition of ambient temperature. From the optimized crystal structure, the CH/O interactions included in the crystal structure were evaluated using NBO method. In this work, we showed that the density functional calculation is a powerful method to investigate the detail structure and the arrangement in the crystal and the nano-structured materials.
Two-contact Circular Test Structure for Determining Specific Contact Resistivity
Authors: Pan Y. , Reeves G. K. , Leech P. W. , Tanner P. , Holland A. S. 
Published: December 2013

ABSTRACTAs ohmic contacts decrease in size and approach nanoscale dimensions, accurate electrical characterization is essential, requiring the development of suitable test structures for this task. We present here a new test structure derived from the standard three-contact circular transmission line model (CTLM) [1], for determining the specific contact resistivity of ohmic contacts. This test structure minimizes sources of error which arise from the CTLM by – (i) reducing the number of contacts within one test pattern from three to two, (ii) ensuring the assumption of equipotential metal contacts used in modelling is more easily attained experimentally, and (iii) allowing the fabrication of reduced geometrical dimensions essential for determining low specific contact resistivity values. The analytical expressions are presented and experiment results are undertaken to demonstrate the accuracy of the technique. There are no error corrections required for determining contact parameters using the presented test structure.
Horizontal carbon nanotube interconnects for advanced integrated circuits.
Authors: Dijon Jean , Chiodarelli Nicolo , Fournier Adeline , Okuno Hanako , Ramos Raphael 
Published: December 2013

ABSTRACTHorizontal carbon nanotube (CNT) interconnects are fabricated using a novel integration scheme yielding record wall densities >1013 shell/cm2, i.e. close to the density required for implementation in advanced integrated circuits. The CNTs are grown vertically from individual via structure and subsequently flipped onto the horizontal wafer surface. Various electrode designs are then used to produce different geometries of metal-to-tube contact such as side contact or end contact. CNT lines - 50 to 100 nm wide and up to 20 µm long - are realized and electrically characterized. The sum of the contact resistances from both ends of the lines is close to 500 Ω for 100 nm diameter lines which leads to a specific contact resistance of 1.6 10-8 Ω.cm2 per tube. With the developed technology, post-annealing of the contact does not improve the resistance values. Both chromium and palladium are used as contact metal. While contact resistance is equivalent with the two metals, the resistance per unit length of the lines does change and is better with palladium. This dependence is explained using a tunnelling model which shows that statistics of individual tube-metal contact is required to properly model the electrical results. Direct experimental evidences showing that only a part of the CNTs in the bundle is electrically connected are also given. Our best line resistivity achieved is 1.6mΩ.cm which is among the best results published for horizontally aligned CNTs and the only one with a realistic geometry for future VLSI interconnects.
3D TSV - Influence of electrolyte composites and anneal temperatures to copper protrusion and planarization
Authors: Rudolph Catharina , Wachsmuth Holger , Bartusseck Irene , Parthenopoulos Michael , Goerner Loana , Boettcher Mathias , Grafe Juergen , Wolf Juergen M. 
Published: December 2013

ABSTRACTThe motivation of this study is to provide answers to questions rising with 3D stacking of semiconductor chips. This includes the development and validation of concepts for 1) Through Silicon Via (TSV) formation, 2) metal layer build-up, 3) various types of assembly and packaging concepts and methods, as well as 4) process characterization.The investigations discussed here have been conducted on test wafer (ATEC2) developed by Fraunhofer IZM-ASSID. This design contains dedicated test structures which have been implemented to enable different unit processes and allows easy physical analysis. One of those test structures has been used to study the impact of the TSV density on the stress generation after TSV fill, anneal and CMP (chemical mechanical planarization) including copper protrusion and planarization behaviour. First results of the interaction between different TSV plating bath chemicals, anneal procedures and wafer bow obtained using test wafer ATEC1 were already presented during ICPT 2011.The process flow applied in this investigation was (1) TSV filling by electro-plating, (2) anneal, and (3) CMP. Physical analysis including inline metrology has been conducted between all process steps.The test wafers processed were divided into two groups according to the utilized copper plating bath chemistries. The copper TSV metallization was carried out by electro-chemical deposition in plating bath chemicals from two different suppliers. 3D microscope inspection was conducted for surface analysis. After TSV filling the copper surface shows protrusion on top of the TSVs and ring-shaped non-uniformities around the filled TSV. These structures were analysed after each step of the process flow.An anneal process was conducted after TSV plating. The annealing temperature was varied to investigate its influence on the material properties (protrusion caused by copper recrystallization) and the dip behaviour. The experiments were accomplished at 250 degree Celsius and above.Afterwards all test samples were processed by CMP with different selective slurries and analysed by AFM (atomic force microscopy) and optical methods. Bow and warpage measurements of the test wafers taken after each process step have been analysed.Our investigation has demonstrated the influence of the additives on the behaviour of different plating bath chemistries during temperature treatment (copper recrystallization) and therefore also the planarization behaviour after CMP.
Coherent Clustering of GdN in Epitaxial GaN:Gd Thin Film
Authors: Wu Mingjian , Erwin Steven C. , Trampert Achim 
Published: December 2013

ABSTRACTWe present an in-depth transmission electron microscopy (TEM) study about the character of the Gd atom distribution in epitaxial GaN:Gd thin films grown by molecular beam epitaxy. High-resolution TEM (HRTEM) imaging reveals local lattice distortions of dimensions of a few atom planes only. Geometric phase analysis of HRTEM lattice images quantifies the associated displacement field. The results are explained by means of thin coherently strained GdN clusters with platelet shape being located along the basal plane. This is consistent with the observations obtained from strain contrast dark-field TEM images. Theoretically derived structure models provided by calculations based on density functional theory are used to simulate the HRTEM contrast and to determine the corresponding displacement field for matching the experimental data. Best fit is achieved in case of a coherent GdN bi-layer cluster that conclusively reflects the energy favorable configuration. The formation of the platelet clusters is explainable in the framework of spinodal decomposition.
Kinetics of spinodal decomposition and strain energy effects in Cu-Ni(Fe) nanolaminates
Authors: Jankowski Alan F. 
Published: December 2013

ABSTRACTThe phase transformation of spinodal decomposition proceeds without nucleation and is affected by the alloy composition, temperature, interfaces and gradient energy, as well as the presence of lattice strain. As a consequence, a coherent spinodal can be depressed well below the chemical spinodal within the miscibility gap. Phase separation from a solid solution within the spinodal leads to the formation of characteristic composition wavelengths. In the nickel-based alloy system, a nanolaminate structure is used to initially create an artificial composition fluctuation with unique nanoscale wavelengths. The direct measurement of diffusivity at low temperatures in Cu-Ni and Cu-Ni(Fe), from the spinodal towards room temperature, requires sensitivity to the nanoscale fluctuations in composition. For this purpose, x-ray diffraction scans are used to assess changes in the short-range order of the composition fluctuation and the corresponding changes in the gradient energy, from which an evaluation of lattice distortion effects reveals a peak in strain energy for 2-3 nm composition wavelengths.
Indium Antimonide (InSb) Cavity Resonators based on Planar Plasmonic Terahertz Waveguide
Authors: Shourie Ranjana J. , Satyanarayan M. N. , Umesh G. 
Published: December 2013

ABSTRACTWe present the studies of Terahertz (THz) Semiconductor-Insulator-Semiconductor (SIS) Planar Plasmonic waveguide of Indium Antimonide (InSb) with cavities along the waveguide acting as resonator. The Surface Plasmon Polariton (SPP) modes were confined in the SI interface and resonance behavior and filtering functionality of the device were demonstrated. The transmission characteristic of the structure depends on the interference effects between the SPP mode passing through the cavity and the one returning from the cavity. These effects were observed by studying the transmission from the SIS waveguide as a function of frequency and cavity length and proving analytically using the analogy with microwave transmission line network. Furthermore, we present the SIS cavity resonator’s transmission characteristics which vary with changes in the dielectric constant of the insulator region. Such a study was proposed to incorporate in the structure for sensing of biomolecules in THz region.
Surfactant Mediated Slurry Formulations for Ge CMP Applications
Authors: Basim G. Bahar , Karagoz Ayse , Chen Long , Vakarelski Ivan 
Published: December 2013

ABSTRACTIn this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry.
The Thermal Effects of CMP as a Particle Augmented Mixed Lubrication Tribosystem
Authors: Srivastava Gagan , Higgs C . Fred 
Published: December 2013

ABSTRACTMost chemical mechanical polishing (CMP) researchers assume that the polishing occurs in the mixed-lubrication regime, where the applied load on the wafer is supported by the hydrodynamic slurry pressure and the contact stress generated during the pad-wafer contact. Consequently, the particle augmented mixed lubrication (PAML) approach has been employed as an extremely high-fidelity asperity-scale mixed-lubrication CMP model in the past. Recently, a more computationally efficient PAML approach, PAML-lite, which considers the slurry’s fluid and particle dynamics, the pad/wafer contact mechanics, and the resulting material removal, was introduced. The current work presents the PAML-lite framework with the isothermal assumption relaxed. As a result, wafer-scale interfacial temperatures during CMP can be predicted by considering asperity heating and dissipation of the heat into the solid and fluid media in the sliding contact.
Inhibitory Effects of Areca Nut Extract on Expression of Complement Receptors and Fc Receptors in Human Neutrophils
Authors: Lee Ya‐Yun , Lin Ming‐Bin , Cheng Chi‐Fang , Chang Lien‐Yu , Liu Tsung‐Yun , Hung Shan‐Ling 
Published: December 2013

Background: Chewing of areca quid increases the prevalence of periodontal diseases. Areca nut extract (ANE) inhibits the phagocytic activity of human neutrophils. This in vitro study investigates the effects of ANE on complement‐ and antibody‐opsonized phagocytosis by neutrophils. Expression of complement receptors, Fc receptors, and F‐actin in ANE‐treated neutrophils is also analyzed.Methods: The viability of ANE‐treated neutrophils was determined using the propidium iodide staining method. The possible effects of ANE on the expression of complement receptors and Fc receptors were examined using an immunofluorescence staining method followed by flow cytometry and confocal laser scanning microscopy. The phagocytic activity of neutrophils against complement or immunoglobulin (Ig)G‐opsonized fluorescent beads was analyzed using flow cytometry. Expression of F‐actin was determined using confocal laser scanning microscopy.Results: ANE significantly inhibited the production of complement receptors (CR1, CR3, and CR4) and Fc receptors (FcγRII and FcγRIII) in a concentration‐dependent manner. Treatment of neutrophils with ANE significantly impaired their ability to phagocytose fluorescent beads. ANE also inhibited phagocytosis of fluorescent beads that were opsonized by complement or IgG. Moreover, expression of F‐actin was inhibited after ANE treatment.Conclusions: ANE inhibits the complement‐ and IgG‐mediated neutrophil phagocytosis that may result from reduction of the expression of complement receptors, Fc receptors, and F‐actin formation after ANE treatment. The findings suggest that areca nut chewing may jeopardize the defensive functions of neutrophils and affect periodontal health.
Prepregnancy Obesity and Periodontitis Among Pregnant Females With and Without Gestational Diabetes Mellitus
Authors: Xie Yiqiong , Xiong Xu , Elkind‐Hirsch Karen E. , Pridjian Gabriella , Maney Pooja , Delarosa Robert L. , Buekens Pierre 
Published: December 2013

Background: This study explored whether there is an association between prepregnancy obesity and periodontitis among pregnant females.Methods: A retrospective cohort study was conducted by using data from a previous case‐control study at Woman's Hospital, Baton Rouge, Louisiana. One hundred fifty‐nine pregnant females were recruited at their prenatal care visits. Periodontal status was assessed through dental examinations performed at an average of 31 weeks gestation. Periodontitis was defined as the presence of one or more sites exhibiting probing depth ≥4 mm or clinical attachment level ≥4 mm. A Poisson regression with robust error variance was used to estimate risk ratio (RR) and 95% confidence interval (CI).Results: Prepregnancy obesity was statistically significantly associated with periodontitis during pregnancy, with obese females at 1.7 times higher risk compared with under/normal‐weight females (RR = 1.7, 95% CI = 1.2 to 2.3, P <0.01). There is no difference in the association between maternal obesity and periodontitis between females with gestational diabetes mellitus (GDM) and females without GDM.Conclusion: There is a positive association between prepregnancy obesity and periodontitis among pregnant females.
Improved Birth Weight for Black Infants: Outcomes of a Healthy Start Program
Authors: Kothari Catherine L. , Zielinski Ruth , James Arthur , Charoth Remitha M. , Carmen Sweezy Luz del 
Published: December 2013

Objectives. We determined whether participation in Healthy Babies Healthy Start (HBHS), a maternal health program emphasizing racial equity and delivering services through case management home visitation, was associated with improved birth outcomes for Black women relative to White women. Methods. We used a matched-comparison posttest-only design in which we selected the comparison group using propensity score matching. Study data were generated through secondary analysis of Michigan state- and Kalamazoo County–level birth certificate records for 2008 to 2010. We completed statistical analyses, stratified by race, using a repeated-measures generalized linear model. Results. Despite their smoking rate being double that of their matched counterparts, Black HBHS participants delivered higher birth-weight infants than did Black nonparticipants (P = .05). White HBHS participants had significantly more prenatal care than did White nonparticipants, but they had similar birth outcomes (P = .7 for birth weight; P = .55 for gestation). Conclusions. HBHS participation is associated with increased birth weights among Black women but not among White women, suggesting differential program gains for Black women.
Construction of Early and Midlife Work Trajectories in Women and Their Association With Birth Weight
Authors: Mutambudzi Miriam , Meyer John D. 
Published: December 2013

Objectives. We derived trajectories of the substantive complexity (SC) of work across mid-adult life in women and determined their association with term birth weight. SC is a concept that encompasses decision latitude, active learning, and ability to use and expand one’s abilities at work.Methods. Using occupational data from the National Longitudinal Survey of Youth 1979 and O*NET work variables, we used growth mixture modeling (GMM) to construct longitudinal trajectories of work SC from the ages of 18 to 34 years. The association between work trajectories and birth weight of infants born to study participants was modeled using generalized estimating equations, adjusting for education, income, and relevant covariates.Results. GMM yielded a 5-class solution for work trajectories in women. Higher work trajectories were associated with higher term birth weight and were robust to the inclusion of both education and income. A work trajectory that showed a sharp rise after age 24 years was associated with marked improvement in birth weight.Conclusions. Longitudinal modeling of work characteristics might improve capacity to integrate occupation into a life-course model that examines antecedents and consequences for maternal and child health.
Is a cultural cortical recycling hypothesis likely in relation to economic artifacts?
Authors: Bourgeois-Gironde Sacha 
Published: December 2013

Abstract
Neuroscience of material artifacts production and handling has recently pointed to the likeliness of a cultural cortical recycling hypothesis (Stout et al., 2008). This hypothesis had been more robustly established in the case of symbolic artifacts such as letters and numbers (Dehaene and Cohen, 2007). In both cases the idea is that specific cortical maps dedicated to basic perceptual and/or motor functions were re-used at some point of relatively recent human history (within temporal scales at which anatomical evolutions of the brain cannot take place) in view of the processing of novel cultural items. Optimal functional recycling jointly facilitates and carries over constraints on the processing of these artifacts. It also presumably plays a role in their emergence and morphogenesis. I present theoretical arguments and a preliminary set of behavioral and neurobiological data that might support the speculation that the historical emergence and the typical neural processing of coins — both a material and symbolic artifact which is central for modern economic life — are explained by a similar hypothesis.