bluuebunny/crossref_metadata_2025 huggingface dataset:
MOBILE AGENT BASED CHECKPOINTING WITH CONCURRENT INITIATIONS
Authors: MANDAL PARTHA SARATHI , MUKHOPADHYAYA KRISHNENDU
Published: September 2007

Traditional message passing based checkpointing and rollback recovery algorithms perform well for tightly coupled systems. In wide area distributed systems these algorithms may suffer from large overhead due to message passing delay and network traffic. Mobile agents offer an attractive option for designing checkpointing schemes for wide area distributed systems. Network topology is assumed to be arbitrary. Processes are mobile agent enabled. When a process wants to take a checkpoint, it just creates one mobile agent. Concurrent initiations by multiple processes are allowed. Synchronization and creation of a consistent global state (CGS) for checkpointing is managed by the mobile agent(s). In the worst case, for k concurrent initiations among n processes, checkpointing algorithm requires a total of O(kn) hops by all the mobile agents. A mobile agent carries O(n/k) (on the average) size data.
COMPUTATIONAL POWER OF INTRAMOLECULAR GENE ASSEMBLY
Authors: ISHDORJ TSEREN-ONOLT , PETRE ION , ROGOJIN VLADIMIR
Published: September 2007

The process of gene assembly in ciliates, an ancient group of organisms, is one of the most complex instances of DNA manipulation known in any organism. Three molecular operations Id, hi, and dlad have been postulated for the gene assembly process. We propose in this paper a mathematical model for contextual variants of Id and dlad on strings: recombinations can be done only if certain contexts are present. We prove that the proposed model is Turing-universal.
COMPARING MINIMUM NEIGHBORHOOD EVALUATION SCHEMES FOR FINDING SPATIALLY ROBUST SOLUTIONS
Authors: DRZADZEWSKI GRZEGORZ , WINEBERG MARK
Published: September 2007

The common definition for robust solutions considers a solution robust if it remains optimal when the parameters defining the fitness function are perturbed. A second definition that can be found in the literature: robustness occurs when a solution can be varied spatially without a significant drop in fitness. We propose an alternative operational definition for spatial robustness: both the solution and the neighbourhood around the solution has fitness above a given threshold. With this new definition, we created a set of functions with useful properties to allow for the testing of solution robustness. The performance of a Genetic Algorithm (GA) is then evaluated based on its ability to identify multiple robust solutions based on the above robustness definition. Different neighbourhood evaluation schemes are identified from the literature and compared, with the minimum neighbour technique proving to be the most effective.
SYMMETRY AND COUPLING EFFICIENCY OF THE DEFECT MODES IN TWO-DIMENSIONAL PHONONIC CRYSTALS
Authors: CAO Y. J. , LI Y. Z.
Published: September 2007

We study theoretically the symmetric property and coupling efficiency of the defect modes in a two-dimensional phononic crystal by calculating band structures, field distributions and transmission coefficients of the defect modes. The results show that the point defect could act as a microcavity surrounded by the phononic crystal, and the confining ability of the phononic crystal to the resonant modes strongly depends on the thickness of the phononic crystal. By investigating the transmission spectra, we also find that the defect modes cannot be absolutely excited by the normally incident plane waves. The transmission coefficients are calculated by using the eigen-mode match theory method under the supercell technique, which is applied to the phononic crystals with the defects for the first time.
PHOTOFIELD EMISSION CALCULATIONS BY USING PROJECTION OPERATOR METHOD
Authors: THAPA R. K. , DAS GUNAKAR , GURUNG S. R. , SHARMA B. I. , PATRA P. K.
Published: September 2007

A model calculation of photofield emission is discussed in which initial state wave function has been deduced by using projection operator method of group theory. A spatial dependent vector potential is used to evaluate the matrix element for calculating the photofield emission current density.
THERMOELECTRIC PROPERTIES OF MnSi1.7 FILMS WITH ADDITION OF ALUMINUM AND CARBON
Authors: HOU Q. R. , LIANG D. , FENG X. , ZHAO W. , CHEN Y. B. , HE Y. J.
Published: September 2007

Polycrystalline higher manganese silicide ( MnSi 1.7, HMS) films with addition of aluminum and carbon are prepared on thermally-oxidized silicon substrates by electron beam evaporation and magnetron sputtering, respectively. An aluminum intermediate layer and a carbon cap layer are used as the doping sources. It is found that both the Seebeck coefficient and electrical resistivity are dependent on the amount of aluminum and carbon added to the films. The Seebeck coefficient changes a little in the temperature range 300 to 433 K and decreases considerably above 433 K when aluminum is added to the film. When carbon is added to the film, however, the Seebeck coefficient increases slightly. With addition of aluminum and carbon, the resistivity decreases. As a result, the thermoelectric power factor increases, especially for films with carbon addition. Several activation energies (0.022–0.20 eV) are observed from the curves of logarithm of resistivity versus reciprocal temperature. The larger activation energies of 0.35 and 0.51 eV are consistent with the energy band gaps for higher manganese silicides.
PREFERENTIAL ORIENTATION GROWTH OF AlN THIN FILMS ON Si (111) SUBSTRATES BY LP-MOCVD
Authors: ZHAO YONGMEI , SUN GUOSHENG , LIU XINGFANG , LI JIAYE , ZHAO WANSHUN , WANG LEI , LUO MUCHANG , LI JINMIN
Published: September 2007

Aluminum nitride ( AlN ) thin films were deposited on Si (111) substrates by low pressure metalorganic chemical vapor deposition system. The effects of the V/III ratios on the film structure and surface morphology were systematically studied. The chemical states and vibration modes of AlN films were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The optical absorption property of the AlN films, characterized by ultraviolet-visible-near infrared spectrophotometer, exhibited a sharp absorption near the wavelength of 206 nm. The AlN (002) preferential orientation growth was obtained at the V/III ratio of 10,000 and the preferential growth mechanism is presented in this paper according to the thermodynamics and kinetics process of the AlN growth.
SCHEME FOR IMPLEMENTING THE DEUTSCH–JOZSA ALGORITHM IN ION-TRAP SYSTEM
Authors: ZHAN ZHI-MING
Published: September 2007

We propose a scheme for implementing the Deutsch–Jozsa algorithm in ion-trap system. The scheme is based on resonant sideband excitation, which only requires resonant interactions. Thus the scheme is very simple and the quantum dynamics operation can be realized at a high speed, which is important in view of decoherence. The required experimental techniques are within the scope of what can be obtained in the ion-trap setup.
RINGS OF DEFINABLE SCALARS OF VERMA MODULES
Authors: L'INNOCENTE SONIA , PREST MIKE
Published: September 2007

Let M be a Verma module over the Lie algebra, sl 2(k), of trace zero 2 × 2 matrices over the algebraically closed field k. We show that the ring, RM, of definable scalars of M is a von Neumann regular ring and that the canonical map from U( sl 2(k)) to RM is an epimorphism of rings. We also describe the Ziegler closure of M. The proofs make use of ideas from the model theory of modules.
FINITE PRESENTABILITY OF BRUCK–REILLY EXTENSIONS OF CLIFFORD MONOIDS
Authors: CARVALHO C. A. , RUSKUC N.
Published: September 2007

Let M be a Clifford monoid and let θ be an endomorphism of M. We prove that if the Bruck–Reilly extension BR(M, θ) is finitely presented then M is finitely generated. This allows us to derive necessary and sufficient conditions for Bruck–Reilly extensions of Clifford monoids to be finitely presented.
CLASSIFYING PROJECTIVE MODULES OVER SOME SEMILOCAL RINGS
Authors: DUBROVIN NIKOLAY , PUNINSKI GENA
Published: September 2007

We investigate the module theory of a certain class of semilocal rings connected with nearly simple uniserial domains. For instance, we classify finitely presented and pure-projective modules over these rings and calculate their projective dimension.
DNA Strand Break Repair and Human Genetic Disease
Authors: McKinnon Peter J. , Caldecott Keith W.
Published: September 2007

Each day tens of thousands of DNA single-strand breaks (SSBs) arise in every cell from the attack of deoxyribose and DNA bases by reactive oxygen species and other electrophilic molecules. DNA double-strand breaks (DSBs) also arise, albeit at a much lower frequency, from similar attacks and from the encounter of unrepaired SSBs and possibly other DNA structures by DNA replication forks. DSBs are also created during normal development of the immune system. Defects in the cellular response to DNA strand breaks underpin many human diseases, including disorders associated with cancer predisposition, immune dysfunction, radiosensitivity, and neurodegeneration. Here we provide an overview of the genetic diseases associated with defects in the repair/response to DNA strand breaks.
The Uneasy Ethical and Legal Underpinnings of Large-Scale Genomic Biobanks
Authors: Greely Henry T.
Published: September 2007

Large-scale genomic databases are becoming increasingly common. These databases, and the underlying biobanks, pose several substantial legal and ethical problems. Neither the usual methods for protecting subject confidentiality, nor even anonymity, are likely to protect subjects’ identities in richly detailed databases. Indeed, in these settings, anonymity is itself ethically suspect. New methods of consent will need to be created to replace the blanket consent common to such endeavors, with a consent procedure that gives subjects some real control over what they might consider inappropriate use of their information and biological material. Through their use, these biobanks are also likely to yield information that will be of some clinical significance to the subjects, information that they should have access to. Failure to adjust to these new challenges is not only legally and ethically inappropriate, but puts at risk the political support on which biomedical research depends.
Gene Duplication: A Drive for Phenotypic Diversity and Cause of Human Disease
Authors: Conrad Bernard , Antonarakis Stylianos E.
Published: September 2007

Gene duplication is one of the key factors driving genetic innovation, i.e., producing novel genetic variants. Although the contribution of whole-genome and segmental duplications to phenotypic diversity across species is widely appreciated, the phenotypic spectrum and potential pathogenicity of small-scale duplications in individual genomes are less well explored. This review discusses the nature of small-scale duplications and the phenotypes produced by such duplications. Phenotypic variation and disease phenotypes induced by duplications are more diverse and widespread than previously anticipated, and duplications are a major class of disease-related genomic variation. Pathogenic duplications particularly involve dosage-sensitive genes with both similar and dissimilar over- and underexpression phenotypes, and genes encoding proteins with a propensity to aggregate. Phenotypes related to human-specific copy number variation in genes regulating environmental responses and immunity are increasingly recognized. Small genomic duplications containing defense-related genes also contribute to complex common phenotypes.
Computation and Analysis of Genomic Multi-Sequence Alignments
Authors: Blanchette Mathieu
Published: September 2007

Multi-sequence alignments of large genomic regions are at the core of many computational genome-annotation approaches aimed at identifying coding regions, RNA genes, regulatory regions, and other functional features. Such alignments also underlie many genome-evolution studies. Here we review recent computational advances in the area of multi-sequence alignment, focusing on methods suitable for aligning whole vertebrate genomes. We introduce the key algorithmic ideas in use today, and identify publicly available resources for computing, accessing, and visualizing genomic alignments. Finally, we describe the latest alignment-based approaches to identify and characterize various types of functional sequences. Key areas of research are identified and directions for future improvements are suggested.
Host Genetics of Mycobacterial Diseases in Mice and Men: Forward Genetic Studies of BCG-osis and Tuberculosis
Authors: Fortin A. , Abel L. , Casanova J.L. , Gros P.
Published: September 2007

In humans, genetic factors have long been suspected to contribute to the onset and outcome of tuberculosis. Such effects are difficult to identify owing to their complex inheritance, and to the confounding impact of environmental factors, notably pathogen-associated virulence determinants. Recently, forward genetic approaches in mouse models and in human populations have been used to elucidate a molecular basis for predisposition to mycobacterial diseases. The genetic dissection of host predisposition to infection with Mycobacterium bovis BCG and M. tuberculosis will help to define the key molecules involved in host antituberculous immunity and should provide new insights into this important infectious disease.
Using Genomics to Study How Chromatin Influences Gene Expression
Authors: Higgs Douglas R. , Vernimmen Douglas , Hughes Jim , Gibbons Richard
Published: September 2007

A postgenome challenge is to understand how the code in DNA is converted into the biological processes underlying various cell fates. By establishing the appropriate technical tools, we are moving from an era in which such questions have been asked by studying individual genes to one in which large domains, whole chromosomes, and the entire human genome can be investigated. These developments will allow us to study in parallel the transcriptional program and components of the epigenetic program (nuclear position, timing of replication, chromatin structure and modification, DNA methylation) to determine the hierarchy and order of events required to switch genes on and off during differentiation and development.
Congenital Disorders of Glycosylation: A Rapidly Expanding Disease Family
Authors: Jaeken Jaak , Matthijs Gert
Published: September 2007

Congenital disorders of glycosylation (CDG) are a large family of genetic diseases resulting from defects in the synthesis of glycans and in the attachment of glycans to other compounds. These disorders cause a wide range of human diseases, with examples emanating from all medical subspecialties. Since our 2001 review on CDG ( 36 ), this field has seen substantial growth: The number of N-glycosylation defects has doubled (from 6 to 12), five new O-glycosylation defects have been added to the two previously known ones, three combined N- and O-glycosylation defects have been identified, the first lipid glycosylation defects have been discovered, and a new domain, that of the hyperglycosylation defects, has been introduced. A number of CDG are due to defects in enzymes with a putative glycosyltransferase function. There is also a growing group of patients with unidentified defects (CDG-x), some with typical clinical presentations and others with presentations not seen before in CDG. This review focuses on the clinical, biochemical, and genetic characteristics of CDG and on advances expected in their future study and clinical management.
Multistage Sampling for Genetic Studies
Authors: Elston Robert C. , Danyu Lin , Gang Zheng
Published: September 2007

In the past, to study Mendelian diseases, segregating families have been carefully ascertained for segregation analysis, followed by collecting extended multiplex families for linkage analysis. This would then be followed by association studies, using independent case-control samples and/or additional family data. Recently, for complex diseases, the initial sampling has been for a genome-wide linkage analysis, often using independent sib-pairs or nuclear families, to identify candidate regions for follow-up with association studies, again using case-control samples and/or additional family data. We now have the ability to conduct genome-wide association studies using 100,000–500,000 diallelic genetic markers. For such studies we focus especially on efficient two-stage association sampling designs, which can retain nearly optimal statistical power at about half the genotyping cost. Similarly, beginning an association study by genotyping pooled samples may also be a viable option if the cost of accurately pooling DNA samples outweighs genotyping costs. Finally, we note that the sampling of family data for linkage analysis is not a practice that should be automatically discontinued.
Human Evolution and Its Relevance for Genetic Epidemiology
Authors: Cavalli-Sforza Luigi Luca
Published: September 2007

The invitation to write the prefatory article to this volume of the Annual Review of Genomics and Human Genetics inspired me to collect some thoughts, a few involving ideas that are not new, but perhaps worth resurrecting in light of recent observations made with the data emerging from the Human Genome Diversity Project (HGDP). Data from the many relevant studies based on the HGDP have been made public, as was originally the hope and plan of the project. Here I try to give a short summary of the evolution of modern humans, a unique species in many respects but of special interest to readers of this volume, and a few thoughts on the general rates of evolution that might be relevant to medical genetics and genetic epidemiology. I have made no attempt to give a general bibliography, not even of results from the HGDP, since most authors' conclusions are still unpublished. Citations are limited to very few general concepts and articles discussed in this preface.
Mapping, Fine Mapping, and Molecular Dissection of Quantitative Trait Loci in Domestic Animals
Authors: Georges Michel
Published: September 2007

Artificial selection has created myriad breeds of domestic animals, each characterized by unique phenotypes pertaining to behavior, morphology, physiology, and disease. Most domestic animal populations share features with isolated founder populations, making them well suited for positional cloning. Genome sequences are now available for most domestic species, and with them a panoply of tools including high-density single-nucleotide polymorphism panels. As a result, domestic animal populations are becoming invaluable resources for studying the molecular architecture of complex traits and of adaptation. Here we review recent progress and issues in the positional identification of genes underlying complex traits in domestic animals. As many phenotypes studied in animals are quantitative, we focus on mapping, fine mapping, and cloning of quantitative trait loci.
Applications of RNA Interference in Mammalian Systems
Authors: Martin Scott E. , Caplen Natasha J.
Published: September 2007

RNA interference (RNAi) can mediate the long- or short-term silencing of gene expression at the DNA, RNA, and/or protein level. Although several triggers of RNAi have been identified, the best characterized of these are small interfering RNAs (siRNAs), which can decrease gene expression through mRNA transcript cleavage, and endogenous microRNAs (miRNAs), which primarily inhibit protein translation. An improved understanding of RNAi has provided new, powerful tools for conducting functional studies in a gene-specific manner. In various applications, RNAi has been used to create model systems, to identify novel molecular targets, to study gene function in a genome-wide fashion, and to create new avenues for clinical therapeutics. Here, we review many of the ongoing applications of RNAi in mammalian and human systems, and discuss how advances in our knowledge of the RNAi machinery have enhanced the use of these technologies.
Influence of the N-Type FinFET Width on the Zero Temperature Coefficient
Authors: Bellodi M. , Martino Joao A. , Camillo L. M. , Simoen E. , Claeys C.
Published: September 2007

This paper presents the influence of the Fin width dimension on the Zero Temperature Coefficient (ZTC) behavior for devices operating at high temperatures (from room temperature up to 573K). Besides this, a simple analytical model is presented in order to describe the ZTC behavior as the temperature increases. Three-dimensional simulations are carried out and compared with experimental results to support the interpretation presented along this work.
Sidewall Angle Influence on the FinFET Analog Parameters
Authors: Giacomini R. , Martino Joao A. , Pavanello Marcelo A.
Published: September 2007

The width variations along the vertical direction, due to process limitations, that appear in some fabricated FinFETs lead to nonrectangular cross-sectional shapes. One of the most frequent shapes is the trapezoidal (inclined sidewalls). These geometry variations may cause some changes in the device electrical characteristics. This work analyses the influence of the sidewall inclination angle on analog parameters, such as voltage gain, transconductance, output conductance, threshold voltage and also on the corner effects, through 3-D numeric simulation.
Improved Compact Model for Symmetric Doped Double-Gate MOSFETs
Authors: Cerdeira A. , Iniguez B. , Estrada M.
Published: September 2007

This paper complements our new compact analytical model for long and short channel symmetric double-gate MOSFETs, which for the first time, considered a doped silicon layer in a wide range of concentrations, between 1014 and 3x1018 cm-3. The already incorporated short channel effects that included threshold voltage variation, DIBL, channel shortening and saturation velocity were further revised and the series resistance effect was included. The model uses the charge control procedure, where the mobile charge density is modeled as function of silicon layer impurity concentration; gate dielectric and silicon layer thickness and applied voltages. Comparison of modeled and simulated (using the ATLAS device simulator) transfer characteristics in linear and saturation regions, as well as output characteristics, shows a good agreement within the practical range of gate and drain voltages and silicon layer doping concentrations.
On the Threshold Voltage of Undoped Double-Gate SOI MOSFETs
Authors: Garcia-Sanchez F. J. , Ortiz-Conde A. , Muci J. , Salazar R
Published: September 2007

Threshold voltage provides valuable information about the behavior and reliability of MOSFET devices. In this paper we review and reexamine various definitions of the threshold voltage of undoped double-gate MOSFETs.
Advanced ESD Protection Solutions in CMOS/BiCMOS Technologies
Authors: Liou Juin J. , Salcedo Javier A. , Liu Zhiwei
Published: September 2007

Robust and novel devices called High Holding, Low-Voltage-Trigger Silicon Controlled Rectifiers (HH-LVTSCRs) for Electrostatic Discharge (ESD) protection of integrated circuits (ICs) are designed, fabricated and characterized. The S-type current-voltage (I-V) characteristics of the HHLVTSCRs are adjustable to different operating conditions by changing the device dimensions and terminal interconnections. Experimental results demonstrate that HH-LVTSCRs with a multiple-finger layout render high levels of ESD protection per unit area, applicable in the design of ICs with stringent ESD protection requirements of over 15 kV IEC.
Stress Analysis on Ultra Thin Ground Wafers
Authors: Teixeira R. C. , De Munck K. , De Moor P. , Baert K. , Swinnen B. , Van Hoof C. , Kuttel A.
Published: September 2007

Grinding wafers is a well established process for thinning wafers down to 100 μm for use in smart cards and stacking chips. As a result of the mechanical process, the wafer backside is compressively stressed. In this paper, the authors investigate the influence of the backside induced stress in ultra thin Si wafers (~20μm). Such aggressive thinning is a requirement for high density vias interconnect, stacked die packaging and flexible electronics.
Anisotropic Resistivity of PMMA Doped with Gold
Authors: Teixeira F. S. , Mansano R. D. , Salvadori M. C. , Cattani M. , Brown I. G.
Published: September 2007

In this work PMMA was deposited on glass substrate, nanolithographed using Atomic Force Microscopy (AFM) and doped with gold using very low energy ion implantation. Samples with different geometries were prepared in order to identify anisotropic resistivity due to an anisotropic surface morphology. One of the samples was fabricated with parallel lines along the substrate length and the second one with parallel lines perpendicular to it. The PMMA with gold implanted presented resistivities in the range 7.7 x 10-8 Ω.m to 0.23 Ω.m. For any PMMA surface morphology the resistivity decreased when the gold dose increased. The anisotropic factor for both morphologies described above presented a prominent peak for a dose of 1.15 x 1016 atoms/cm2. Finally, a new sample of PMMA with gold implanted dose of 1.15 x 1016 atoms/cm2 was prepared and an I-V curve was obtained, showing clearly that the material is a semiconductor.
Dynamic Scaling of the Surface Roughness During Electroless Cu Plating onto Si in Aqueous Fluoride Solution
Authors: Gozzi G. , Dos Santos Flho G.
Published: September 2007

In this work, it is investigated the dynamic scaling of the surface roughness of Cu plated onto (100) Si in a diluted solution composed by hydrofluoric acid (HF) and copper sulphate (CuSO4.5H2O) at room temperature (25oC) for processing times ranging from 1 to 5 minutes. The results revealed a normal scaling law for deposition in 0.15M HF and 0.00315M CuSO4 bath, this is to say, the surface width w(l,t) scales as lH for small l (H≈1.0), where l is the size of the region over which w(l,t) is measured and H is the Hurst exponent. Also, for large l, w(l,t) shows a slight power law dependence on t, scaling as tβ, with β ≈ 0. On the other hand, increasing the HF concentration from 0.15 to 0.80M, the Hurst exponent does not change but the scaling regime becomes anomalous with the root-mean-square interface width w varying as tβloc at short length scales. Finally, these observations were correlated with the scaling exponents of the Cu/Si interface during Cu plating. It was worthy of note that normal regime of the surface Cu occurs for Cu/Si-interface width w(l,t) lower than the Cu-surface width and, in contrast, the anomalous regime of the surface Cu occurs for interface width close to the Cu-surface one.
Effect of the Substrate Heating Due to the Sputtering Process on the Crystallinity of TiO2 Thin Films
Authors: Toku H. , Pessoa R. S. , Liberato T. B. , Massi M. , Maciel H. S. , Da Silva Sobrinho A. S.
Published: September 2007

This article reports on the effect of the increase of substrate temperature due to the plasma discharge on the crystalline structure of the TiO2 thin films deposited on silicon by the magnetron sputtering technique. The influence on the film crystallinity was evaluated as a function of process parameters, such as, substrate-to-target distance and reactive gas concentration. The substrate holder was equipped with two thermocouples in order to measure simultaneously the substrate temperature Ts and the substrate surface temperature Tsurf during the deposition. The films were analyzed by X-ray diffractometry (XRD) and profilometry. Results show that the critical temperature to obtain crystalline films depends upon the gas composition and it varies from 170ºC - 210ºC for oxygen concentration in the gas mixture varying from 20 to 100%.
Improvement of Polymeric Electroluminescent Device Structures Through Simulation of UV-Vis Absorption Spectra of PANI/PVS Films
Authors: Lima J. P. , De Andrade A. M.
Published: September 2007

Artificial neural networks (ANN) were used to simulate the absorption spectra of PANI/PVS films deposited by the layer-bylayer (LBL) technique with different number of bilayers and doping levels. The PAni/PVS films are used to enhance electrical and optical performance of polymeric electroluminescent devices. In this work one hidden-layer Multilayer Perceptron (MLP) architecture was used. It is shown a comparison between experimental and simulated UV-Vis absorption spectra. This approach is proposed for the determination of thin-film design so as not to overlap the absorption spectra of Pani/PVS films with the device active layer emission spectra in order to enhance the device performance.
Contact Improvement for Carbon Nanotubes Deposited by Dielectrophoresis
Authors: Leon J. , Vaz A. R. , Flacker A. , Moshkalev S. A. , De Moraes M. B. , Swart J. W.
Published: September 2007

A method of dielectrophoresis was applied to align and deposit multi-wall carbon nanotubes between pre-fabricated metal (Au, Pd) electrodes with a micron scale separation. For improvement of nanotube contacts with electrodes, metal electroless process was used. Significant improvement of 2 terminals resistances was demonstrated. Further, using electron and ion beam deposited Pt contacts in two different configurations, 4 terminals measurements have been performed to evaluate intrinsic nanotube resistances. The values between 30 and 130 kΩ/μm were obtained for nanotubes with diameters in the range from 15 to 40 nm.
The Influence of Substrates on the Carbon Nanotube Growth Process
Authors: De Aguiar M. R. , Verissimo C. , Moshkalev S. A. , Swart J. W.
Published: September 2007

Carbon nanotubes (CNTs) have attracted much attention due to their extraordinary properties. This nanostructured material has been synthesized by various methods and the chemical vapor deposition (CVD) has been shown to be an efficient and versatile technique. In this work, catalytic thermal CVD method, using a mixture of methane and hydrogen at atmospheric pressure on a horizontal tubular quartz furnace, was used to grow carbon nanotubes. Silicon wafers with SiO2 or Al2O3 layers were used as substrates whereas thin nickel film was deposited over the substrates and used as catalyst. The interaction between catalyst nickel film and two different oxide layers supported on silicon wafers was studied as well as the influence of both substrates (Si/SiO2 and Si/Al2O3) on the carbon nanotube growth. It was observed a completely different interaction between Ni film and both oxide layers, affecting strongly the growth of CNTs.
Etching Studies of Post-Annealed SiC Films Deposited by PECVD: Influence of the Oxygen Concentration
Authors: Fraga M. A. , Pessoa R. S. , Massi M. , Maciel H. S. , Dos Santos Filho S. G.
Published: September 2007

Amorphous silicon carbide thin films (SiC) were produced by PECVD technique at room temperature. Post-annealing was used to crystallize the SiC films. These films were etched in reactive ion etching system using SF6 + O2 gas mixtures. The influence of O2 concentration in process was investigated by mass spectrometry technique. Using this technique, it was possible to estimate the better conditions where the etching rates are optimal and also to verify the contributions of etchant species like F and O on the production of the main volatile products SiF4, CO and CO2.
Deposition and Characterization of Indium-Tin Oxide Thin Films Deposited by RF Sputtering
Authors: Damiani L. R. , Mansano R. D.
Published: September 2007

Tin-doped indium oxide (ITO) is an n-type degenerate semiconductor routinely used as an electrode in various optoelectronic devices such as flat panel displays, solar cells and organic electroluminescence devices due to its unique combination of properties, including high optical transparency, low electrical resistance and excellent surface adhesion. The purpose of this work is to find out the best method of obtaining ITO thin films through RF sputtering process. The ITO samples used in this study were obtained by reactive RF sputtering; each one acquired with different sputtering parameters, in special the RF power. The characterization of the samples was made by measuring their thickness and refraction index in three different wavelengths. Measures as sheet resistances and atomic percentages were also found by equipments such as ellipsometer, four point probe and micro analyse.
Electrical Characterization of a-C:H as Insulator Material in MIM Structures
Authors: Zuniga-I C. , Kosarev A. I. , Torres-J A. , Reyes-Betanzo C. , Calleja-A W. , Rosales P.
Published: September 2007

a-C:H with low dielectric constant is a very interesting material for applications as inter-metal insulator material in modern ICs, due to the compatibility of deposition process with silicon technology. In this work the fabrication and electrical characterization of Metal- Insulator-Metal structures using a-C:H as the insulating material is presented. The carrier transport mechanisms in high and low electric field regimes are presented. Structures with Ti electrodes show a transport mechanism controlled by the space charge limited current in the low electric field regime, and a Schottky mechanism in the high electric field regime. Preliminary studies in structures with Al electrodes exhibit a different behavior, the transport mechanism does not look like neither Shocktty nor SCL micahnisms. We propose that a-C:H film is an excellent material for inter-metal insulation applications.
Physical Characterization and Reliability Aspects of MuGFETs
Authors: Claeys C. , Simoen E. , Rafi J. M. , Pavanello Marcelo A. , Martino Joao A.
Published: September 2007

Multi-gate devices are explicitly mentioned in the ITRS roadmap and have a good potential for scaling to the 32 nm and below technology nodes. Worldwide much attention is given to FinFET and MuGFET device architectures. This paper reviews some physical characterization and reliability aspects of such devices. Attention is given to aspects such as transient floating body effects, their performance at both high and low temperatures, gate coupling effects and their low frequency noise behavior. In addition, their potential radiation hardness in view of space applications is outlined.
The Impact of the Gate Oxide Thickness Reduction on the Gate Induced Floating Body Effect in SOI nMOSFETs
Authors: Der Agopian Paula G. , Martino Joao A. , Simoen E. , Claeys C.
Published: September 2007

This work presents the influence of the gate oxide thickness (toxf) reduction on the gate induced floating body effects (GIFBE) in different Silicon On Insulator (SOI) technologies, through experimental results and two-dimensional numerical simulations. The occurrence of the floating body effect displacement and the threshold variation with toxf reduction are investigated. The continuous reduction of toxf suggests that the first and second transconductance peaks tend to overlap each other.
Modeling Negative Differential Resistance (NDR) Devices using Radial Basis Function Neural Networks
Authors: Banderia M. C. , Guimaraes J. G. , Duraes J. A. , Silva L. M. , Ceschin A. M. , Sales M. J. , Costa J. C.
Published: September 2007

This paper presents, for the first time, models for NDR devices based on radial basis neural networks and MATLAB routines. These models were carried out for devices, such as RTDs and a buriti oil single-layer, operating at room temperature. A RTD circuit was successfully simulated using the developed neural network model.
The Length-Dependence of the 1/f Noise of Graded-Channel SOI nMOSFETs
Authors: Simoen E. , Claeys C. , Chung Tsung M. , Flandre D. , Raskin Jean-Pierre
Published: September 2007

This paper describes a low-frequency (LF) noise study of Graded- Channel Fully Depleted (FD) Silicon-on-Insulator (SOI) n-channel MOS transistors, with special emphasis on the length dependence. It is shown that the LF noise is predominantly 1/f-like with a current noise spectral density behaving in most cases according to the trapping model. While a clear improvement in the linear transfer characteristics is obtained for the GC structure, compared with the uniformly doped FD or the undoped intrinsic devices, the LF noise magnitude is found to be larger, which may be detrimental for analog/RF applications. It is demonstrated here that the higher noise is associated with the extra current in the GC nMOSFET, giving rise to excess fluctuations which are probably associated with generation-recombination events at the boundary between the extrinsic and the intrinsic part of the device.
10 GHz RF Passive Components Obtained by MCM-D Technology
Authors: Zoccal L. B. , Cabreira C. M. , Yamamoto S. D. , Flacker R. A. , Gomes E. A. , Diniz J. A. , Swart J. W.
Published: September 2007

Thin film multi layer MCM-D (Multi Chip Module Substrate) technology was developed for application on RF (radio-frequency) circuits aiming passive components (capacitors and inductors) and transmission line patterns integration. Metallic layers, using gold and nickel-phosphorus, and dielectric (non-conductive) layers, using Benzocyclobutene (BCB) resin and silicon nitride, were deposited on alumina substrate to manufacture MCM-D structure. Semiconductor integrated circuit (IC) manufacturing techniques were adapted and employed to get high quality and accurate passive components and circuits. Modeling of passive components and transmission lines patterns used electromagnetic simulation tools. RF (up to 10GHz) on-wafer measurements were done on manufactured structures and shown good agreement with simulation results demonstrating that it is applicable on RF devices and modules covering many wireless applications as GSM, BlueTooth and HyperLAN. Focused Ion Beam (FIB) was used for structure analysis and layer thickness measurements.
Three-Dimensional (3-D) Electro-Thermal Simulation of Four-Layer Devices
Authors: Quientero-Romo R.
Published: September 2007

An approach to three-dimensional (3-D) electro-thermal computer simulation of transient over-voltage protectors (TOVP's) is presented for the first time. The numerical size of the problem is reduced to that of a two-dimensional (2-D) problem by assuming cylindrical symmetry. The complex electro-thermal behavior revealed by the simulations can be useful both for device modeling and design.
Stability of Coupled Quantum Dot Cells at Finite Temperatures
Authors: Batistuta M. V. , Stella M. F. , Da Costa J. C.
Published: September 2007

Coupled quantum dot cells are the basic functional structures in implementing Quantum Cellular Automata (QCA), which may offer higher computational capabilities for integrated circuits. In this work a transport dynamics model, and a robust numerical simulation strategy, for behavior prediction and optimization were developed, where thermal noise is considered in order to validate stable operation at finite temperatures.
Silicon Microtips Arrays Fabricated by HI-PS Technique for Application in Field Emission Devices
Authors: Dantas M. O. , Kopelvski M. M. , Galeazzo E. , Peres H. E. , Fernandez J. R.
Published: September 2007

This work presents results of silicon field emission devices fabrication from HI-PS technology. A dedicated system based on virtual instrumentation was developed to characterize samples electrically. From this system, it was possible to extract I-V curves and to analyze the behavior of devices related to the electrical emitting field obtained for each one. Si microtips arrays were compared by extracting the field enhancement factor g from the curves and applying it as a quality parameter. The g factor differences between the samples (about 0.46 and 0.59) indicate a good improvement of emission characteristics of devices in comparison with Si planar samples.
Simple MEMS-based Incandescent Microlamps
Authors: Rehder G. , Carreno M. N. , Alayo M. I.
Published: September 2007

In this work, the fabrication and operation of micro-incandescent lamps is presented. Two types of microlamps are fabricated using micro-cantilevers and micro-bridges of silicon oxynitride (SiOxNy) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) at low temperatures (320{degree sign}C) with embedded chromium thin film resistors. In both cases, the chromium resistor is sandwiched between layers of SiOxNy that isolates it from the atmosphere, while electric current heats the resistor to incandescent temperatures. Front-side bulk micromachining of the silicon substrate in KOH solution is used to fabricate the cantilevers and bridges that thermally isolate the resistors from the substrate, thus reducing the heat transfer and current required to light the lamp. Finally, arrays of bridges are used to fabricate arrays of microlamps that can be polarized as a micro-display.
Simulation, Fabrication and Characterization of a Tunable Bragg Reflector Based on Silicon Oxide and Silicon Nitride Dielectric Films Deposited by PECVD
Authors: Martins G. S. , Baez H. , Alayo M. I.
Published: September 2007

of a Tunable Bragg Reflector based on dielectric silicon oxide and silicon nitride films deposited over corning-glass substrates by Plasma Enhanced Chemical Vapor Deposition at low temperatures (320 oC). The device consists of consecutive layers of silicon oxide and silicon nitride films with appropriated refractive indices and thickness to function as an interferential filter in the visible region. The optical results of these devices are comparable to the numerical simulations previously realized, showing an attenuation peak in the transmittance curve at approximately 680 nm. Also, when an angular variation between the incident light beam and the optical filter is produced, a shift in the attenuation peak is observed, which is due to a difference in the optical path of the incident beam. This behavior agrees with simulated results. When a change in temperature is applied to the optical device, a shift in the attenuation peak is also observed, which is related to the thermo-optic effect (TOE) of this kind of material. These results demonstrate that it is possible to control the optical output power of the device through the adequate control of the angle of the incident beam and/or temperature of the device.
Microstructural and Electrical Conductivity Relationships in Alumina- Containing Yttria Stabilized Cubic Zirconia Used as a Solid Electrolyte in Solid Oxide Fuel Cells
Authors: Tekeli S. , Kayis A. , Gurdal O. , Guru M.
Published: September 2007

Cubic zirconia is a well known material that has good oxygen ionic conductivity and chemical stability over wide ranges of temperature and oxygen partial pressure and thus it has been developed for use in a variety of electrical applications such as oxygen sensors, oxygen pumps, thermal barriers and solid oxide fuel cell electrolytes. In the present study, the effect of Al2O3 addition on the microstructure and electrical conductivity of 8 mol% yttria stabilized cubic zirconia doped with up to 10 wt% Al2O3 was investigated. The electrical conductivity of the specimens was measured using a frequency response analyzer in the frequency range of 5-13 MHz and in the temperature range of 300-800 oC. The experimental results showed that the addition of Al2O3 led to decreased grain size due to grain boundary pinning and increased grain boundary volume. It was also seen that grain conductivity slightly increased with increasing Al2O3 content up to 1 wt% and further increase in Al2O3 led to a decreased in the conductivity.
Precision Recycle Process of ITO Removal from Color Filter Using Electrochemical Machining
Authors: Pa P. S.
Published: September 2007

A new design modus using electrochemical machining as a precision recycle process of ITO layer removal from optoelectronic flat panel displays' color filter surfaceinstead of the chemical etching is developed. Through the ultra-precise removal of thin film microstructure, the semiconductor optoelectronic industry can effectively recycle defective products, reducing production costs. In the current experiment, the author takes a 5th Generation TFT-LCD for instance. A higher temperature or a higher concentration of the electrolyte corresponds to a higher removal rate for ITO layer. Pulsed direct current can improve the effect of dregs discharge and is advantageous to associate with the fast feed rate of workpiece. But raises the current rating. An adequate feed rate of color filter combine with enough electric power produces fast machining. The electrochemical machining just needs quite short time to make the ITO film remove easily and cleanly. An effective and low-cost recycle process is presented.
Effect of Number of Layers on the Optical Response of Porous Silicon Bragg's Mirrors
Authors: Huanca D. R. , Salcedo W. J.
Published: September 2007

The present work reports the influence of the number of layers in the porous silicon (PS) Bragg´s mirrors optical performance. The electrochemical process used to obtain the PS mirror device imposes a limit on the number of layer since for long time process the chemical dissolution compete with electrochemical dissolution effect. However, the high number of layer in the mirror device avoided the optical response degradation after thermal annealing process.
Influence of the Interferers in the Nitrite Detection By using Planar Electrochemical Sensors
Authors: Ameida F. L. , Fontes M. B.
Published: September 2007

Reproducibility, sensibility and selectivity are standard parameters on the development of sensors. In this article we described a planar electrochemical sensor based silk-screened to detect nitrite and its interferers - paracetamol, ascorbic acid and uric acid. We modified the working electrode gold surface by using 1-2 diaminobenzeno (DAB) membrane in order to reduce the interferers. Preliminary results showed which using DAB there is decrease of interference signal about three times. We obtained a sensibility about 310 μA/(mol.L-1.mm2) for nitrite, using plain electrode and 90 μA/(mol.L-1.mm2) after DAB membrane. Although the actual results are promising, we are evaluating several combinations of membranes to reduce more the influence of the interferers in the nitrite detection.
Characterizaton of a Isfet Device as a pH Sensor for Application in the Industrial, Environmental and Biomedical Fields
Authors: Scaff R. , Fontes M. B. , Dos Santos Filho S. G.
Published: September 2007

The most extensively investigated MOSFET-based chemical sensor is the so-called ion sensitive field effect transistor or ISFET. The device was invented by Bergveld around 1970 (1) and is capable of measuring the pH of an electrolyte. A great demand exists for miniaturized chemical sensors for a multitude of applications in the industrial, environmental and biomedical fields. An ISFET consists of a MOSFET, where the oxide layer is replaced by a combination of an oxide layer and a solution containing ions. The pH of a solution (associated to the effective concentration of hydrogen ions) determines the electrochemical potential of the gate (reference) electrode and thus the potential (threshold voltage) shifts. This shift is a measure of the pH. In addition, an alternative interpretation of the IDS x VGS characteristic is proposed based on the subthreshold modeling of the MOS structure.
Macroporous Silicon Structure Functionalized by Methylene Blue to pH Measurements Application
Authors: Raimundo D. S. , Cechelero G. S. , Acosta A. , Fernandez F. R. , Salcedo W. J.
Published: September 2007

The present work reports the obtaining of a macroporous silicon structure functionalized by methylene blue to pH sensors applications. The porous silicon (PS) structure was obtained using an anodization process in a HF/DMF (N,N-dimethylformamide) solution. The PS film was firstly functionalized with 3- aminopropiltrimetoxisilane (APS) molecules using the Grafting method. After it, the structure was functionalized by methylene blue (MB) molecule to the obtaining of the modified electrode. PSMB modified electrode presented good performance as pH sensor device, showing that the previous treatment of the macroporous surface with Cl3SiR molecules in toluene promoted better stability and performance of the PS-MB modified electrode.