bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical zonation of the hydroid Dynamena crisioides (Hydrozoa, Sertulariidae) in a mangrove ecosystem at Twin Cays, Belize
Authors: Calder Dale R.
Published: August 2008

Dynamena crisioides is generally restricted to lower intertidal and shallow subtidal habitats along tropical and subtropical coasts. The hydroid was abundant during this study on prop roots of red mangroves (Rhizophora mangle) at Twin Cays, Belize, where it ranged vertically from 1.1 m below mean tide level (MTL) to 2–3 cm above MTL. The estimated percentage cover of the hydroid was maximal in the lower half of the intertidal zone (MTL and 0.1 m below MTL) and declined rapidly above and below that level. Colony height and number of branches per colony were also consistently highest in hydroids from the lower half of the intertidal zone. The percentage of colonies with gonophores was lowest at the lower and upper vertical limits of the species. Field observations and transplantation experiments suggest that the lower limits of D. crisioides are established by competition for space (with algae, sponges, and ascidians), smothering (by algae, sponges, ascidians, and other hydroids), and predation (by fishes). Desiccation was considered the prime factor determining the upper limits of the hydroid. Colonies transplanted to the supratidal zone were in good condition after 24 h, alive but in poor condition after 48 h, and dead after 72 and 96 h of exposure.
Comparisons of steroid production and density of LH binding sites in guinea pig ovarian follicles destined to ovulate and destined to become atretic
Authors: Hamilton G. S. , Tam W. H.
Published: August 2008

Two waves of follicular recruitment exist in the 16-day estrous cycle of the guinea pig. One lasts from days 2 to 10 and contains follicles that are all destined to become atretic, while another lasts from days 7 to 16 and includes several follicles destined to ovulate. Healthy-appearing follicles of greater than 0.6 mm were isolated on days 6, 9, and 15 of the cycle to investigate specific characteristics of the two consecutive waves of follicles. Follicles were compared on the bases of LH binding site density and steroid synthetic capacity. Large day-9 and day-15 follicles were shown to have similar densities of LH binding sites and also were capable of synthesizing and secreting large amounts of estrogen following incubation in media supplemented with hCG or testosterone. However, only day-15 large follicles were able to produce large amounts of estrogen in unsupplemented media, which suggests that they had already been exposed to endogenous LH prior to their removal from the ovary. Estrogen production by the large day-9 follicles was negligible when they were incubated in unsupplemented media. These follicles of the first wave of folliculogenesis would not have experienced a similar exposure to endogenous LH in vivo, since it is known that serum concentrations of LH are low during days 6–10 of the cycle. It is postulated that the lower estrogen production by large day-9 follicles may also be associated with the inability to undergo other maturational events essential for ovulation.
Comparison of helminths of three species of mice, Podomys floridanus, Peromyscus gossypinus, and Peromyscus polionotus, from southern Florida
Authors: Kinsella J. M.
Published: August 2008

The helminths of 102 Florida mice, Podomys floridanus, 86 cotton mice, Peromyscus gossypinus, and 41 old-field mice, Peromyscus polionotus, from the Lake Wales ridge of southern Florida were studied. Nineteen species of helminths were found, and high indexes of similarity were found among the three host species. A trichostrongylid nematode, Carolinensis peromysci, and a pinworm, Syphacia peromysci, were common to all three hosts and accounted for 80% of all helminths collected. A liver fluke, Zonorchis komareki, and Carolinensis peromysci were more prevalent in mice from bayhead habitats, and two spirurid nematodes, Pterygodermatites peromysci and Gongylonema sp., were more prevalent in mice from flatwoods habitats. Other helminth species included four apparently derived from the cotton rat, Sigmodon hispidus, two from the eastern cottontail, Sylvilagus floridanus, and two from the raccoon, Procyon lotor. The helminth fauna of these three mice, which live in relatively xeric habitats, was dominated by nematodes.
Nest-site fidelity in a centrarchid fish, the smallmouth bass (Micropterus dolomieui)
Authors: Ridgway Mark S. , MacLean James A. , MacLeod J. Cameron
Published: August 2008

Individual nesting male smallmouth bass (Micropterus dolomieui) in Lake Opeongo, Ontario, were followed for 11 years to determine the degree of nest-site fidelity from one year to the next. Only data from males nesting for the first and second time in consecutive years were included. The data indicate that 21.4% of all first-time nesting males returned to nest the following year. Nesting males rarely skipped a year after their 1st year of nesting. There was a strong tendency for males to return close (<20 m) to their previous year's nest site. Approximately 81 % renested within 200 m of their previous nest site, while the remainder nested between 200 and 1200 m from their previous nest site. This is the first report of nest-site fidelity for individual fish and is similar to published accounts of nest fidelity in birds.
CONSTRUCTING INTEGRABLE COUPLINGS FOR THE C-KdV HIERARCHY
Authors: LI LING , DONG HUANHE , LIU JINYUAN
Published: August 2008

By using the variational identity, the Hamiltonian structures of the C-KdV hierarchy, integrable couplings of C-KdV hierarchy, (2+1)-dimensional C-KdV hierarchy as well as the multi-component integrable system are obtained.
THERMOFIELD ANALYSIS OF MAGNON SQUEEZING STATE IN THE FERROMAGNET
Authors: XU QINFENG , CHENG ZE , PING YUNXIA
Published: August 2008

In this paper, we introduce the self-consistent field approximation to treat with the nonlinear interaction among spin waves. Then temperature-dependent Bogoliubov transformation is introduced to generate a new representation which engenders the transition from the zero temperature to the finite temperature. At last, temperature-dependent quantum fluctuation properties of magnons are discussed in the thermal field. At lower temperature, we find that the fluctuation of spin-component at some given time regions can be below the zero-point fluctuation level of the vacuum state and exhibit a periodical squeezing behavior. In particular, these squeezed effects vanish with the increasing of temperature. These squeezing effects differ from the previous studies.
SEGREGATION OF Cu IN THE Cu/Ni MULTILAYERS
Authors: LI L. Y. , YU G. H. , ZHU F. W.
Published: August 2008

The segregation of Cu atoms in the Cu/Ni multilayers was investigated by means of the full-potential linearized augmented plane-wave method with the generalized-gradient approximation formula. We investigated the segregation of Cu atoms when the Cu/Ni slab is along the (001) and (111) directions, respectively. The results obtained show that at most one-layer Cu atoms can segregate to the Ni surface when Ni films are deposited on the Cu substrate and the segregation of Cu atoms is not sensitive to the orientation of the Cu/Ni slab surface. The result of Cu segregation is to reduce the vacuum effect.
Direct Electrical Detection of Biological Species
Authors: De Sagazan Olivier , Harnois Maxime , Girard Aurelie , Le Bihan France , Salaun Anne-Claire , Crand Samuel , Mohammed-Brahim Tayeb
Published: August 2008

Suspended-Gate FETs, namely SGFET, with sub-micron gap, is shown to be able to detect biological species with very high sensitivity in a large range of concentration. Examples of detection of DNA (through the DelF508 mutation of the cystic fibrosis gene that is widely disseminating in Europe and North America, and one mutation of BRCA1 gene that is the main indication of the possibility for a woman to have breast cancer) and proteins (through the transferrin that is the only carrier of iron in blood) are presented. This very sensitive electrical detection without any labelling is shown to deliver directly readable signal.
Electrical and Optical Response of a Conducting Polymer Gas Sensor
Authors: Lima John Paul H. , De Andrade Adnei M.
Published: August 2008

This work deals with the electrical and optical response of poly (o-methoxyaniline) (POMA) thin films exposed to nitrogen and nitrogen with methanol. A low cost apparatus was developed for the optical assessment of the presence of methanol in an ambient. It is shown that thick POMA films exhibits a wide optical absorption variation when in presence of methanol. It was observed that the optical absorption characteristics return to the initial condition when methanol exposition ceases. Electrical response of a photoresistor to methanol showed larger relative variations but also presented large noise interference. A residual drift in the resistance is presented after every cycle and it need to be better evaluated.
Time-of-Flight Flow Sensor Microstructure Using Free-Standing Polysilicon Filaments
Authors: Rodrigues Roberto J. , Furlan Rogerio
Published: August 2008

In this work we present a time-of-flight flow microsensor implemented using surface micromachining in combination with sacrificial layer technology. This approach allows obtaining free-standing polysilicon microfilaments that can be used as heaters or temperature sensors. The obtained microstructure can find applications in many important areas as process and environmental control, biomedicine and instrumentation. Numerical simulation showed a compromise between the size of the device (distance heater to sensor) and the range of volumetric flow to be detected. Also, the proposed structure is suitable for the detection of low volumetric flows and presents a response time of the order of milliseconds. Experimental results demonstrate that the heater can be operated at a temperature of the order of 100{degree sign}C with a power dissipation of ~ 30 mW. Also, tests with the implemented flow sensor structure and characterization apparatus revealed a good agreement with respect to the numerical simulation, confirming the predicted behavior.
Simulation of Anisotropic Etching of Silicon using a Cellular Automata Model
Authors: De Oliveira Jose P. , Carreño Marcelo N.
Published: August 2008

In this work we present a 3D simulation software for anisotropic etching of crystalline silicon substrates in KOH solutions. The software is based on conventional cellular automata model, and integrates in the same environment, the simulator itself with different 2D and 3D graphics tools to define simulation parameters and for visualization purposes. The software simulates the etching of (100) oriented Si substrates through open regions in a masking material with arbitrary geometry, with any number of holes and island in the masking material, which can be isolated or one inside the others. The simulator also works with both, front and back side etching of the substrate at the same time. The results show that, even though the model is based on fixed and simple transitions rules to determine if a specific atom is removed or not by the etching process, the simulation results exhibit a quite good accordance with the experimental results.
Complete Microfluidic System Fabricated in Glass Substrates
Authors: Schianti Juliana N. , Mielli Murilo Z. , Lopes Alexandre T. , Carreño Marcelo N.
Published: August 2008

This paper reports the fabrication of complete microfluidic system utilizing Corning 7059 glass substrates. The method utilized to obtain the microfluidic system, combines techniques such as photolithography and wet etching to produce the microchannels and room temperature direct bonding as an encapsulating process. Mechanical drilling with dental diamond bur was utilized to produce access holes for external interconnections. To guarantee the necessary alignment during the encapsulation process, a computer controlled system was developed to move and position the dental bur utilized to make the access holes. The structures were characterized by optical and electronic microscopy and video camera was utilized for liquid flow characterization. The obtained results show that the proposed fabrication method is fast, reproducible and allow the fabrication of glass microchannels with depths up to 150 mm, without evidence of liquid leakage. For the all the studied conditions, we observed a liquid flow with laminar behavior.
Piezoelectric Stimulation of Microcantilever Beams for Young's Modulus Determination of Amorphous Hydrogenated Silicon Carbide
Authors: Rehder Gustavo P. , Carreño Marcelo N.
Published: August 2008

In this work, the resonant frequency of cantilevers actuated using a piezoelectric ceramic disk is measured by optical means. Groups of amorphous hydrogenated silicon carbide (a SiC:H) microcantilevers, that are fabricated by bulk micromachining of a silicon substrate, are used to extract the Young's modulus on different locations of the sample, which allows us to a map this mechanical property along the entire surface of the film. The determination of the Young's modulus of a-SiC:H is essential for the design and development of MEMS using this material. Specially because this material has low residual and gradient stresses, 70 MPa (compressive) and 36 MPa/μm, respectively, and its modulus of elasticity was determined to be 91 GPa, with small variation. The modulus of sputtered chromium was also measured (285 GPa).
ARX Model of Elastic Nuclei for Rotors MEMS
Authors: Reimbold Manuel M. , Chong Wang , Leandro Gideon V. , Ribas Renato P.
Published: August 2008

This work proposes a new procedure to extract characteristic parameters of MEMS structures, using systems identification. The target structures are the nuclei of micro-rotors and the characteristic parameters are the mass, the damping coefficient, and the spring constant. The structures are described in 3D solid model and the behavioral data necessary to the extraction of characteristic parameters, used in macro-models, are obtained through numerical simulations based on finite elements. To parameter extraction were adopted the ARX model and the RLS estimator. Experimental data obtained from three topologies of micro-nuclei, with one degree of freedom, demonstrates satisfactory estimate results when applied to analytical models that the extracted parameters, when applied to analytical models, which motivates the application of other techniques available in the systems identification domain.
Simulation and Fabrication of Suspended-Membrane Resistive Microbolometers Using Gold-Black as Absorber
Authors: Della Lucia Felipe L. , Swart Jacobus W. , Zoccal Leonardo B. , Diniz José A. , Doi Ioshiaki , Frateschi Newton C.
Published: August 2008

This work presents thermal, mechanical and electrical simulations of a microbolometer and the fabrication of the device. It is used ANSYS for the FEM mechanical simulation and ATLAS for the thermal and electrical simulation. The fabrication methods and steps are described and preliminary results show good prediction by the simulations.
Halo Optimization for 0.13um SOI CMOS Technology
Authors: Agopian Paula G. , Arrabaça Julia M. , Martino João A.
Published: August 2008

This work presents the study of HALO implantation angle and its concentration influence on deep-submicrometer partially depleted SOI nMOSFETs electric characteristics. This study was performed through the threshold voltage and subthreshold slope analysis. As the implantation angle and the doping concentration of the HALO were varied, a large threshold voltage variation was obtained. It is demonstrated that for 0.13um SOI CMOS technology devices, the most efficient HALO implantation occurs for 50 degrees.
Behaviour Study of Low-Loss Slow-Wave Coplanar Transmission Lines for RFIC Applications
Authors: Kaddour Darine , Issa Hamza , Abdelaziz Marwa , Podevin Florence , Pistono Emmanuel , Duchamp Jean-Marc , Ferrari Philippe
Published: August 2008

Slow wave coplanar transmission lines (S-CPW), based on conventional coplanar CPW transmission lines with a floating patterned ground plane, consisting in floatting strips below the line, are good candidates for the integration of distributed RF circuits for front-end modules. They offer high quality factors when compared to conventional coplanar transmission lines. In this paper, guidelines are carried out for the design of such transmission lines. Simulations are first compared to already published measurements thus validating the simulation method used throughout the paper. Next, considering a standard 0.35 µm CMOS process, a design guideline is drawn in order to determine the characteristic impedance, the phase velocity and the dielectric effective constant of the S-CPW transmission lines, along with the attenuation loss and the quality factor. The effects of the floating strips duty cycle, the floating strip width and the ground plane width are studied.
Adjustment of Microwave Integrated Circuit (MIC) with Focused Ion Beam (FIB)
Authors: Zoccal Leonardo B. , Vaz Alfredo , Yamamoto Silas D. , Moschkalev Stanislav , Diniz José A. , Swart Jacobus W.
Published: August 2008

Microwave Integrated Circuit (MIC) technology allows flexibility for customization design, reduced design cost and time-to-market, and adjusting capabilities not enable with MMIC circuits. Development of radio frequency (RF) devices requires adjusting pads and alternative circuit layouts connected with wire bonding. Circuits cutting are possible but it is coarse, with no precision and requires a costly metallic film deposition by sputtering process. We have developed a cheaper process by previous Ni-P deposition to improve Au film adhesion. However cutting circuits in adjustments became very difficult. Furthermore more complex RF devices may have critical circuits in which adjustment pads or alternative circuits highly influence the performance disenabling its use. Focused Ion Beam (FIB) by its accuracy allows circuit adjusting (milling circuit lines) with high accuracy. A dual coupler filter in a MIC technology was adjusted using this process. Results demonstrated adjustment is simple and precise in agreement with electromagnetically simulated circuits.
Proposal of a New Planar Micro-Antenna in LTCC Substrate for System on Chip
Authors: Costa Crezo M. , Fontgalland Glauco , De Melo Marcos A. , Freire Raimundo C. , Vuong Tan-Phu , Morimoto Nilton
Published: August 2008

In this paper some parameters are combined to obtain an efficient antenna miniaturization that could be suitably used in systems on chip applications. Theses parameters are geometries in ring, slot and gap, commonly applied in size reduction of planar antennas. As an important element in sensor networks, the antenna should be compact and lightweight, and have high efficiency and low power consumption. To be well integrated (adapted and matched to the sensor circuits) the antenna design was made in LTCC (Low Temperature Co-fired Ceramic) substrate. The simulations with commercial software are compared with measurements presenting good results. The examples presented suggest the design of new types of structures. The results can be used as a first step guide to design miniaturized patch antennas.
A Series Association Model For Double Gate Graded-Channel SOI nMOSFET Analog Circuit Simulation
Authors: Ferreira Francisco A. , Cerdeira Antonio , Pavanello Marcelo A.
Published: August 2008

In this work we present the development of an equivalent series association analytical model for double gate (DG) Silicon-on-Insulator (SOI) nMOSFET transistor with graded-channel (GC) that is valid from weak inversion to strong inversion. Through the use of DG analytical models available in the literature, considering an equivalent structure represented by two transistors with different doping levels in series association, with short-circuited gates, each one simulating a GC channel region, we have got a model of the DG GC SOI nMOSFET. Atlas numerical two-dimensional simulations and experimental results are used to validate the proposed model. Good agreement between simulated, modelled and experimental results is found.
Efficient and Accurate Neural Network-Based Macro-models for Spiral Inductors
Authors: Ilumoka Abby A. , Srinivasan Raghuveer J.
Published: August 2008

A neural network approach is presented for efficient and accurate model parameter extraction for integrated circuit spiral inductors. The approach involves the creation of neural network models which use spiral inductor geometric characteristics for prediction of s- and y-parameters over the frequency range 0.1GHz - 100GHz. The objective is to develop an efficient replacement neural model for spiral inductors - a circuit element for which a detailed simulation model already exists. The approach is especially attractive because it is capable of modeling skin and proximity effects as well as changes in effective series resistance at higher frequencies. Additionally, the neural network macro-model can predict important inductor characteristics such as Q-factor and self-resonant frequency. Substantial computational savings over detailed circuit simulation are available - ranging from 88 % to 95%.
3D Triple-Gate Simulation Considering the Crystallographic Orientations
Authors: Conde Jorge E. , Cerdeira Antonio , Pavanello Marcelo A.
Published: August 2008

Current in FinFET's transistors flows along two different crystallographic orientations, since, typically the FIN top region orientation is <100>, while the sidewalls have <110> orientation. In this paper we present how to represent the mesh structure for these devices, in order to simulate in 3-D, considering different mobility values for each orientation. Results of 3-D simulation considering also the effect of the series resistance are shown and compared with experimental results.
Strained-Si MOSFETs for Low-Power Applications
Authors: Maiti Tapas K. , Das Tanmoy , Das Partha S. , Sarkar Subir K. , Maiti Chinmoy K.
Published: August 2008

CMOS device/circuit performance involving mobility-enhanced strain-engineering in the channel region is studied via process and device simulations. It is shown that strained-Si (SS) devices could be applied for low-power design by lowering supply voltage. A physics-based stress induced mobility model has been developed and implemented in Synopsys Sentaurus Device simulator. The trade-offs for power and performance in strained-Si devices and circuits are discussed.
An Improved Current Model in Saturation for Trapezoidal Finfets
Authors: Martins Gustavo P. , Giacomini Renato C. , Martino João A.
Published: August 2008

In order to obtain a more accurate equation for the trapezoidal FinFET current model, some new considerations were done to improve an already-published model. The most important is related to the device partition. The original derivation partitioned the device into horizontal slices, each of them considered as a double-gate elementary transistor, in parallel association with the others. The observation of the FinFET electric potential behavior, obtained from three-dimensional numeric simulation, leaded to a more adequate definition of these elementary transistors, mainly at the edges, and consequently to a new saturation current equation. The improved model was compared to the original, through the analysis of the current-voltage equations, for trapezium angles in the 60 to 90 degrees range, and different doping levels. The new model showed to be more accurate than the previous for higher doping levels and more inclined sidewalls, when both were compared to numeric simulation results.
Corner Effect on Capacitance-Voltage Curves in Triple Gate FinFET
Authors: Rodrigues Michele , Sonnenberg Victor , Martino João A.
Published: August 2008

The corner effect in Triple Gate FinFET is investigated through gate capacitance versus gate voltage curves. The influence of different fin doping concentrations is observed using three-dimensional numerical simulations. The analysis of fin doping concentrations confirms the presence of two threshold voltages for high doping levels, which are associated to the corner region early inversion. For a fin doping concentration higher than 2x1018 cm-3 the corner effect in capacitance versus gate voltage curve can not be neglected anymore and have to be taken into account for parameters extraction.
Influence of Fin Width on the Intrinsic Voltage Gain of Standard and Strained Triple-Gate nFinFETs
Authors: Pavanello Marcelo A. , Martino João A. , Simoen Eddy , Rooyackers Rita , Collaert Nadine , Claeys Cor
Published: August 2008

This work studies the influence of the fin width on the intrinsic voltage gain of standard and strained Si (sSOI) n-type triple-gate FinFETs with high-k dielectrics and metal gate. It is demonstrated that independent of the fin width the application of strain improves the device transconductance. On the other hand, the device output conductance shows a high dependence on the fin width in strained FinFETs with respect to standard ones. The output conductance degrades if narrow fins are used and improves for wide fins. Narrow strained FinFETs show a degradation of the Early voltage compared to standard ones suggesting that strained devices are more subjected to the channel length modulation effect.
Channel Length Influence on the Performance of Source-Follower Buffers Implemented with Graded-Channel SOI nMOSFETs
Authors: De Souza Michelly , Flandre Denis , Pavanello Marcelo A.
Published: August 2008

This work presents an evaluation of the influence of channel length on the performance of graded-channel (GC) SOI nMOSFETs operating as source-follower buffers. Experimental data is used to compare the buffer gain and linearity of GC and standard SOI nMOS transistors for different mask channel lengths and similar effective channel length. Two-dimensional numerical simulations were also performed, showing that the gain of buffers implemented with GC devices remains close to the theoretical limit even when short-channel devices are used. The simulated results indicate that the length of a source-follower buffer using GC devices can be reduced by a factor of 5, in comparison with the standard counterpart, without gain degradation or linearity worsening.
Linearity Analysis in Double Gate Graded-Channel Soi Devices Applied to 2-Mos Mosfet-C Balanced Structures
Authors: Doria Rodrigo T. , Cerdeira Antonio , Raskin Jean-Pierre , Flandre Denis , Pavanello Marcelo A.
Published: August 2008

This paper examines the linearity of 2-MOS MOSFET-C balanced structures using conventional and Graded-Channel (GC) Gate-All-Around (GAA) devices. The distortion analysis has been performed through the evaluation of third order harmonic distortion (HD3). The study has been carried out through experimental results, two-dimensional process and device simulations. Along this work, the best operation bias in terms of HD3 is determined for each analysed device and the couple device that exhibits lower HD3 is pointed out. The use of GC GAA devices in 2-MOS structures has showed to improve the linearity in relation to the conventional GAA. Finally, a discussion over the non-linearities causes is performed clarifying their origins and the improvement provided by the adoption of GC GAA devices in 2-MOS structures.
Radiation Effects on Programmed NROM Cells
Authors: Corso Domenico , Palermo Andrea , Palumbo Felix R. , Libertino Sebania , Lombardo Salvatore , Lisiansky Michael , Roizin Yakov
Published: August 2008

NROM type non-volatile memories, having information charge stored in traps in silicon nitride layer, were subjected to different radiation sources in order to ascertain the radiation hardness. Fundamental device parameters, such as threshold voltage shift and current leakages were studied as function of the accumulated dose for gamma (60Co) and Boron ions irradiations to emulate real radiation environments for space and avionics applications. Radiation tolerance of NROM cells was registered with a pronounced degradation for doses exceeding 50 Krad and 1x1010 B/cm2 for gamma and Boron ions irradiations respectively.
Characteristics of Titanium Oxide Gate Nmosfet Formed by E-Beam Evaporation with Additional Rapid Thermal Oxidation and Annealing
Authors: Barros Angélica D. , Miyoshi Juliana , Wada Ricardo , Cavarsan F. A. , Doi Ioshiaki , Diniz José A.
Published: August 2008

High k insulators, such as titanium oxide, have been obtained by Ti e-beam evaporation, using different thicknesses of 5nm, 10nm and 20nm with additional rapid thermal oxidation and annealing at temperature of 960{degree sign}C for 40s. Characterization by Fourier transform infrared analyses reveals the Ti-O and Si-O bonds, which confirms titanium oxide formation. Raman spectroscopy identified that these films present rutile and anatase phases. nMOSFETs and MOS capacitors, with Al electrodes and final sintering at 450{degree sign}C for 10min in forming gas, were fabricated. MOS capacitors were used to obtain capacitance-voltage measurements, and to extract the Equivalent Oxide Thickness from the films, resulting in values between 16.3nm and 19.7nm, and effective charge densities of about 1011cm-2. nMOSFET electrical characteristics, such as threshold voltages between 0.39V and 0.43V and sub-threshold slopes between 61mV/dec and 100mV/dec, were obtained. These results indicated that the TiOx films are suitable gate insulators for MOS devices.
Photoluminescence in Silicon-rich PECVD Silicon Oxynitride Alloys
Authors: Ribeiro Marcia , Pereyra Inés
Published: August 2008

Silicon-rich silicon oxynitride films have been produced by PECVD technique in order to study its photoluminescence. The films with higher silicon content exhibit photoluminescence in the visible spectral region as deposited. On the other hand films with lower silicon content require heat treatment to show appreciable emission. The deposited films were characterized by: Rutherford back scattering (RBS), Raman scattering, Fourier Transform Infrared spectroscopy (FTIR) and photoluminescence (PL). The results suggest that the films present amorphous silicon clusters and the photoluminescence is compatible with a quantum confinement phenomenon in the amorphous silicon clusters.
Electrical Characterization of Electrodeposited Co/p-Si Schottky Diodes
Authors: Zandonay Ricardo , Delatorre Rafael G. , Pasa André A.
Published: August 2008

Schottky diodes were prepared by photoinduced electrodeposition of Co on p-Si, probing the influence of different concentrations of CoSO4 (26 and 104 mM) in the electrolyte on the electrical quality of the metal-semiconductor interface. Current-voltage (I×V) measurements were performed in diodes with different thickness to obtain the barrier heights and ideality factors, based on thermionic emission theory. Devices with improved properties were obtained by increasing the thickness of cobalt. Saturation currents with values of about 0.1 mA were obtained for thick metallic layers. By increasing thickness of cobalt was also possible to observe ideality factors close to 1.19 in diodes exhibiting barrier heights of 0.65 eV.
Etching Characteristics and Surface Morphology of Nitrogen-Doped a-SiC Films Prepared by RF Magnetron Sputtering
Authors: Fraga Mariana A. , Pessoa Rodrigo S. , Oliveira Ivo C. , Massi Marcos , Maciel Homero S. , Martinho Herculano , Dos Santos Filho Sebastião G. , Marcuzzo Jossano S.
Published: August 2008

Amorphous nitrogen-doped silicon carbide (a-SiCxNy) thin films were deposited on Si substrates by RF magnetron sputtering of a SiC target in a N2+Ar atmosphere. The N2/Ar flow ratio was adjusted by varying the N2 flow rate and maintaining constant the Ar flow rate. In order to investigate the influence of N2/Ar flow ratio on composition, bonding structure, morphology and surface roughness of the deposited films, the following techniques were used: Rutherford backscattering spectroscopy (RBS), Raman spectroscopy and atomic force microscopy (AFM). Moreover, using a reactive ion etching (RIE) system the a-SiCxNy samples were etched in SF6+O2 gases mixtures. To better understand the variation of the etching rate as a function of the nitrogen content in the film, temporal mass spectrometry analysis of main effluents generated during etching process was performed.
Bird's Beak and Thermally Induced Stress Defects Evaluations of LOCOS Structures Fabricated Using ECR-CVD SiNx Without Pad Oxide
Authors: Scalise Heraldo , Doi Ioshiaki , Diniz José A.
Published: August 2008

Silicon Nitrides were deposited on the silicon substrates by ECR-CVD (electron cyclotron resonance chemical vapor deposition), without using the pad oxide in LOCOS (LOCal Oxidation of Silicon) isolation technology. The SiNx/Si structure was used to substitute the SiNx/SiO2/Si. The study of this type of the structure was motivated by the possibility to reduce the length of the bird's beak. Defects were created on silicon because the high temperature (1000ºC) applied on SiNx/Si. The Dash wet chemical etch was used to etch the defect on silicon. Optical and SEM microscopy analysis were used to investigate the bird's beak in the obtained LOCOS structures and the defects (dislocations) on silicon performed after high temperature process.
Electroless Deposited Nickel Hard Mask for High Density Plasma Etching Applications
Authors: Nunes Alcinei M. , Moshkalev Stanislav A. , Flacker Alexander , Tatsch Peter Jurgen , Besseler E.
Published: August 2008

Ni electroless films were used as a material for hard mask during high-density ICP plasma etching. The results have shown that under the plasma exposure strong hardening of the mask occurs and the rate of Ni film removal falls at least an order of magnitude as compared with its initial value. Therefore, very high selectivities for Si etching over Ni are obtained, allowing for very deep etching required for some MEMS applications.
Considerations about Interconnection Effects in Basic Single-Electron Circuits
Authors: Carneiro Vitor A. , Scandaroli Thacio G. , Guimarães Janaina G. , Da Costa Jose C.
Published: August 2008

In this work, an investigation about the interconnection effects in single-electron circuits is carried out by simulation. Circuit models for interconnections are presented, considering different materials, areas and lengths. Furthermore, a possible solution for decreasing the interconnect effects is proposed.
Fabrication of Multi-point Test Structures Using Focused Ion Beam and Selective Carbon Nanotubes Deposition by Dielectrophoresis
Authors: Silva Marcelo M. , Vaz Alfredo , Veríssimo Carla , Moshkalev Stanislav A. , Swart Jacobus W.
Published: August 2008

In this work, we present experimental procedures developed for fabrication of multi-point test structures using focused ion beam. The test structure is fabricated in two steps: (i) metal (Au, Pd) electrodes are fabricated by lift-off technique. (ii) nanocontacts are fabricated by ion beam induced deposition of platinum and milling with Ga ion beam. The multi-wall nanotubes (MWNT) are deposited by dielectrophoresis method between metal electrodes. Our test structure allows measurements using 2 and 4 terminals methods.
Multi-Efficiency Position-Sensitive Detector with Linearized Response
Authors: Vaisman Chasin Adrian N. , Salles Luciana P. , De Lima Monteiro Davies W.
Published: August 2008

This paper presents a discussion about alternative layouts for a two-dimensional optical position-sensitive detector, namely a quad-cell, featuring different sensitivity regions (i.e. quantum efficiencies). Our aim is to find out the best distribution of these regions in order to improve the linearity of its response, taking into account the number of regions, their respective sensitivity and radii. Simulation results of a numerical model provide an indication to the best cell configuration.
Observation of Resonance Modes in InAs/InGaAsP/InP Quantum Dot Microdisk Resonators
Authors: Mialichi Jose R. , Barea Luis A. , Von Zuben Antonio A. , Frateschi Newton C.
Published: August 2008

We present the development of quantum dot microdisk resonators grown by Chemical Beam Epitaxy (CBE). Two stacked layers of InAs Quantum Dots (QDs) embedded in a lattice-matched InGaAsP (λg=1.4 μm) are grown on (100) InP substrate. Evidence of the presence of resonant modes are observed both by eletroluminescense and absorption spectra at room temperature.
Tio2 Anti-Resonant Layer Arrow Waveguides
Authors: Carvalho Daniel O. , Alayo Marco I.
Published: August 2008

The simulation, fabrication and characterization of ARROW waveguides using dielectric films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and Sputtering techniques, are presented in this work. Amorphous titanium oxide (TiO2) films were used as first cladding layer and silicon oxynitride (SiOxNy) films, as core and second cladding layers. Furthermore, homemade routines based in two computational methods were developed, for numerical simulations: Transfer Matrix Method (TMM) for the determination of the optimum thickness values of the Fabry-Perot layers, and the Finite Difference Method (FDM) for 2D design and determination of the maximum width that allows single-mode operation. The utilization of titanium oxide as first anti-resonant layer resulted in low optical attenuations, since high interlayer refractive index differences can be obtained.
Analytical Model for a Mixed Association of Photovoltaic Cells
Authors: Barcelos Tulio M. , De Lima Monteiro Davies W. , Lessa Moisés F.
Published: August 2008

This work provides analytical expressions for the parameters of the one-exponential equation to describe the I-V behavior of any compound series-parallel association of photovoltaic solar cells. The parameters might be used to predict the association output characteristic by converting it to one single equivalent expression of a photovoltaic cell. These expressions are based on individual-cell parameters obtained from a linear approximation at both short-circuit and open-circuit regions and were modified in order to account for the effect of the non-uniform incident irradiation. The expressions have been implemented in MATLAB® and the resulting I-V curve for an arbitrary photovoltaic module has been contrasted with the results of a numerical circuit model, based on empirical parameters, implemented on a SPICE platform, for the sake of validation.
Charge Transport Layers in OC1C10-PPV PLEDs
Authors: Gimaiel Helena L. , Santos Gerson , Dirani Ely Antonio T. , Fonseca Fernando J. , De Andrade Adnei M.
Published: August 2008

This work deals with OC1C10-PPV based active layer PLEDs. A study of the device performance enhancement with nanolayers of Alq3 [tris-(8-hydroxyquinolate)-aluminum] deposited at the contact interface between the electroluminescent layer and the cathode was conducted. Alq3 layers of different thicknesses were applied to the structures. A fourfold gain in the luminance of the devices was observed in the studied range. Operating voltage has a strong dependence on Alq3 layer thickness. Luminance values over 500 cd/m2 for 1 nm Alq3 thick films were observed.
Field Emission Studies in a Conducting Sphere-Plane Electrodes System
Authors: Dall'Agnol Fernando F. , Paulo Alexandre C. , Angeles Pablo J. , Santos Thebano E. , Mammana Victor P.
Published: August 2008

In this article the electrical potential and field are calculated analytically for a conducting sphere at a fixed voltage and a grounded conducting plane using the method of images. This electrodes configuration has some advantages compared to the usual plane electrodes configuration. The model was applied to fit field emission data of copper obtained in a sphere-plane configuration of electrodes. Simulations with this model provide good insight of the field emission features that is used to understand anomalous behaviors in the Approach Curve Method.
Asymmetry and Rectification in Tunnel Current of All Polymer Diode
Authors: Sousa Bruno , Dos Santos Joao Paulo , Guimarães H. H. , Guimarães Janaina G. , Ceschin Artemis M.
Published: August 2008

In this paper, we present the fabrication of an all polymer diode, including the substrate and the electrodes. An insulating film of polymethylmethacrylate (PMMA) is sandwiched between two polymer electrodes: a poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) and assembled in a polyester flexible substrate. The IxV curves show not only asymmetry but also exhibit current rectification. Also, the IxV curves suggest the existence of different electron transport mechanisms in each interface metal-insulating and insulating-metal.
A Contribution to the Development of Organic Semiconductor Displays by the Inkjet Technique
Authors: Frazatti Alex , De Andrade Adnei M.
Published: August 2008

Organic Light Emitting Diodes - OLEDs - is a promising field of study and a huge market opportunity for the semiconductor players. Thanks to its potential characteristics to replace the today's main display technologies like lightweight, low operation voltage, wide viewing angle, high resolution, fast switching, broad color range and the possibility to produce flexible devices, makes the organic semiconductors a potential candidate to develop, in a near future, devices and systems that even could not be imagined. This work aims to contribute to the manufacturing process field and to the characterization of displays prepared by the ink jet deposition technique. In this work, a study was done on the morphology of the ink jet deposition of polyfluorene over Indium Tin Oxide (ITO) substrates treated with different procedures. An adapted commercial desktop ink jet printer was used to deposit the polymer films. The devices were characterized by optical, electrical and performance measurements.
Mechanism Design of Rotational Magnetic Assistance Electrochemical Finishing on Freeform Surface
Authors: Pa P.S.
Published: August 2008

The current study investigates a new finishing process that uses a rotational magnetic assistance with high efficiency to assist discharging dregs from the electrode gap during the electrochemical finishing on freeform surfaces. The factors affecting the effects of the magnetic assistance in electrochemical finishing are primarily discussed. This study used Taguchi's Method to analyze the combination of optimal parameters. The experimental parameters use four factors and three levels to measure the surface roughness of the magnetic-assistance in the electrochemical finishing. These four factors include current density, magnetic strength, the distance between the two magnets, and rotational speed of the magnets. For the design system, the large current density with magnetic assistance can circumvent the difficulty of dreg discharge, thus reducing the finishing time. Smaller distances between the two magnets or larger magnetic field intensities provide larger magnetic strength, discharge ability and a better finish. A higher rotational speed of the magnets produced a better finish. The average effect of the magnetic assistance was greater than the pulsed current while the machining time did not need to be prolonged by the off time. The magnetic assistance in electrochemical finishing needing a short amount of time to make the freeform-surfaces smooth and bright is recommended.
Study of a Low Cost Reballing of BGA Method with Lead-Free Solder Paste
Authors: Mazon Talita , Prevedel Guilherme E. , Schenkel Egont A. , Biasoli Marcio T.
Published: August 2008

Due to environmental consciousness and legislative regulations, lead-free solders have been replaced most of the conventional lead-containing solders in microelectronic industry. In response to the concern over Pb used in electronic products and manufacturing electronics, much work is ongoing to find new parameters for re-balling process. This paper describes a low cost reballing method with lead free solder paste on BGA (Ball Grid Array) packages. It was used a lead free solder paste with composition Sn 96,5%, Ag 3,0% and Cu 0,5% and the reflow technology. The results obtained were compared with the conventional reballing method. The solder properties such as wetting characteristics as well as the amount of solder paste deposited by dispenser onto the substrate bond pads influenced on the formation of the bumps. By controlling the volume of solder paste deposited and the parameters used during the reflow step it was possible to obtain bumps liked semi spherical format that can be used to replace the solder balls on the conventional rework of BGA.
The gastric mucus layers: constituents and regulation of accumulation
Authors: Phillipson Mia , Johansson Malin E. V. , Henriksnäs Johanna , Petersson Joel , Gendler Sandra J. , Sandler Stellan , Persson A. Erik G. , Hansson Gunnar C. , Holm Lena
Published: August 2008

The mucus layer continuously covering the gastric mucosa consists of a loosely adherent layer that can be easily removed by suction, leaving a firmly adherent mucus layer attached to the epithelium. These two layers exhibit different gastroprotective roles; therefore, individual regulation of thickness and mucin composition were studied. Mucus thickness was measured in vivo with micropipettes in anesthetized mice [isoflurane; C57BL/6, Muc1−/−, inducible nitric oxide synthase (iNOS)−/−, and neuronal NOS (nNOS)−/−] and rats (inactin) after surgical exposure of the gastric mucosa. The two mucus layers covering the gastric mucosa were differently regulated. Luminal administration of PGE2increased the thickness of both layers, whereas luminal NO stimulated only firmly adherent mucus accumulation. A new gastroprotective role for iNOS was indicated since iNOS-deficient mice had thinner firmly adherent mucus layers and a lower mucus accumulation rate, whereas nNOS did not appear to be involved in mucus secretion. Downregulation of gastric mucus accumulation was observed in Muc1−/− mice. Both the firmly and loosely adherent mucus layers consisted of Muc5ac mucins. In conclusion, this study showed that, even though both the two mucus layers covering the gastric mucosa consist of Muc5ac, they are differently regulated by luminal PGE2and NO. A new gastroprotective role for iNOS was indicated since iNOS−/− mice had a thinner firmly adherent mucus layer. In addition, a regulatory role of Muc1 was demonstrated since downregulation of gastric mucus accumulation was observed in Muc1−/− mice.
Reduced absorption of saturated fatty acids and resistance to diet-induced obesity and diabetes by ezetimibe-treated andNpc1l1−/−mice
Authors: Labonté Eric D. , Camarota Lisa M. , Rojas Juan C. , Jandacek Ronald J. , Gilham Dean E. , Davies Joanna P. , Ioannou Yiannis A. , Tso Patrick , Hui David Y. , Howles Philip N.
Published: August 2008

The impact of NPC1L1 and ezetimibe on cholesterol absorption are well documented. However, their potential consequences relative to absorption and metabolism of other nutrients have been only minimally investigated. Thus studies were undertaken to investigate the possible effects of this protein and drug on fat absorption, weight gain, and glucose metabolism by using Npc1l1−/−and ezetimibe-treated mice fed control and high-fat, high-sucrose diets. Results show that lack of NPC1L1 or treatment with ezetimibe reduces weight gain when animals are fed a diabetogenic diet. This resistance to diet-induced obesity results, at least in part, from significantly reduced absorption of dietary saturated fatty acids, particularly stearate and palmitate, since food intake did not differ between groups. Expression analysis showed less fatty acid transport protein 4 (FATP4) in intestinal scrapings of Npc1l1−/−and ezetimibe-treated mice, suggesting an important role for FATP4 in intestinal absorption of long-chain fatty acids. Concomitant with resistance to weight gain, lack of NPC1L1 or treatment with ezetimibe also conferred protection against diet-induced hyperglycemia and insulin resistance. These unexpected beneficial results may be clinically important, given the focus on NPC1L1 as a target for the treatment of hypercholesterolemia.