bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Frequency Loss Mechanism in Polymers Filled with Dielectric Modifiers
Authors: Obrzut J. , Anopchenko A. , Kano K. , Wang H. 
Published: April 2011

ABSTRACTWe analyzed the high frequency dielectric relaxation mechanism in high-k composite materials using film substrates made of low loss organic resin filled with ferroelectric ceramics and with single wall carbon nanotubes (SWNT). We performed broadband permittivity measurements of high-k film substrates at frequencies of 100 Hz to about 10 GHz. In order to analyze the effect of the dielectric thickness, dielectric constant, loss and conductive loss on the impedance characteristics, we used a High Frequency Structure Simulator to perform a full wave numerical analysis of several power planes. Small angle neutron scattering (SANS) was used to probe the dispersion of SWNTs in polymer matrices. It was found that organic-ceramic composites exhibit an intrinsic high frequency relaxation behavior that gives rise to frequency dependent dielectric loss. The highest frequency relaxation process dominates the overall loss characteristic. In the case of polymers modified with SWNTs, we observed that 2% mass fraction of p-doped semi-conducting SWNTs increases the dielectric constant by 3 orders of magnitude, in apparent violation of the mixing-rule. The hybrid material appears to have preferential coupling within the dispersed phase. The experimental data and numerical simulation indicate that these materials can play a significant role as embedded passive devices with functional characteristics superior to that of discrete components.
Tunability of Bi-rich BZN Cubic Pyrochlore Thin Films by Reactive Sputtering
Authors: Back Dong Hyuk , Lee Yoon Seop , Hong Young Pyo , Moon Joong Ho , Ko Kyung Hyun 
Published: April 2011

ABSTRACT(Bi3xZn2−3x)(ZnxNb2−x)O7 thin films (x=1/2 and 2/3) have potential great for tunable RF and microwave devices due to medium dielectric constant and low dielectric loss. The tunable dielectric properties of Bi-rich, (Bi1.5 Zn0.5)(Zn0.5 Nb1.5)O7 thin films were investigated. To make Bi-rich cubic pyrochlore thin films, Bi2O3–ZnO–Nb2O5 monoclinic pyrochlore ceramic targets were used in reactive RF magnetron sputtering process. Substrate heating was employed to improve surface morphology and tunability. As-deposited films were crystallized or amorphous state depending on substrate temperature. All films were annealed at 600°C ∼ 800°C for 3 hours in the air. There were no zinc niobate secondary phases in the films before and after post-annealing, while quite significant amount BZN thin films were found in sputtered using cubic pyrochlore ceramic targets, especially after post-annealing. It was found that Bi-rich BZN films have much larger tunability when as-deposited phase are amorphous. The maximum tunability 38% was obtained when substrate is heated to 350°C and composition of films is close to exact stoichiometric cubic BZN.
High Frequency, High Density Interconnect Using AC Coupling
Authors: Franzon Paul , Kingon Angus , Mick Stephen , Wilson John , Luo Lei , Chandrasakhar Karthik , Xu Jian , Bonafede Salvatore , Huffman Alan , Statler Chad , LaBennett Richard 
Published: April 2011

ABSTRACTAC Coupled Interconnection (ACCI), in conjunction with buried solder bump technology, provides a method to achieve signal I/O pitches of less than 75 μm and signaling rates greater than 5 Gbps per I/O on integrated circuits, while preserving excellent signal integrity. This paper presents a summary of approaches, status, and discusses material issues important to performance.
Microstructural Evolution of Cu/Ta/GaAs Multilayers with Thermal Annealing
Authors: Wu Wei-Cheng , Chen Chang-You , Lee Chen-Shih , Chang Edward Yi , Chang Li 
Published: April 2011

ABSTRACTCopper metallization for GaAs was evaluated by using Cu/Ta/GaAs multilayers for its thermal stability. A thin Ta layer of 30 nm thickness was sputtered on the GaAs substrate as the diffusion barrier before copper film metallization. As judged from the results of sheet resistance, X-ray diffraction, Auger electron spectroscopy and transmission electron microscopy, the Cu/Ta films on GaAs were very stable up to 500 °C without Cu migration into GaAs. After 550 °C annealing, the interfacial mixing of Ta with GaAs substrate occurred, resulting in the formation of TaGa2 and TaAs2, and the diffusion of Ga and As through the Ta layer formed the Cu3Ga and Cu3As phases at the Cu/Ta interface. After 600 °C annealing, the reaction of GaAs with Ta and Cu formed TaAs and Cu3Ga, as a result of Cu migration and interfacial instability.
Ferroelectric memory in La substituted Bi4Ti3O12 thin films
Authors: Melgarejo R. E. , Tomar M. S. 
Published: April 2011

ABSTRACTThe recent demonstration of large ferroelectric memory in rare earth substituted Bi4Ti3O12 attracted a lot of research interest in this material. Bi4-xLaxTi3O12 was synthesized by sol-gel route for different compositions: x = 0.00, 0.46, 0.56, 0.75, 0.95 and thin films were deposited by spin coating on Pt (Pt/TiO2/SiO2/Si) substrate. The post annealed films at 700°C were studied for their structural studies using x-ray diffraction and Raman spectroscopy. The prominent effect of La substitution is observed in low frequency Raman modes. X-ray diffraction and Raman studies show that the film growth was c-axis suppressed. Using improved contacts to Pt substrate, ferroelectric polarization Pr = 51 μC/cm2 has been achieved for 0.63 μm thick film of composition: x = 0.56 (BLT56) without appreciable fatigue.
Sample Geometry Effects on Electric-Field-Induced Displacements in Piezoelectric Thin Films Measured by Atomic Force Microscopy
Authors: Okino Hirotake , Matsuda Hirofumi , Iijima Takashi , Yokoyama Shintaro , Funakubo Hiroshi , Yamamoto Takashi 
Published: April 2011

ABSTRACTElectric-field-induced displacements of PZT film capacitor Pt/PZT(5μm)/Pt/SiO2/Si(100) were calculated by finite element method with various parameters of sample geometry: the diameter of top electrode φ TE ranging from 0.2 μ m to 1000 μ m and whether PZT film was continuous or side-etched. If φ TE was larger than 40μ m, surface longitudinal displacement (corresponding to AFM-measured strain) was not equal to net longitudinal displacement of PZT film, including a contribution of the bending motion of substrate. In contrast, if φ TE was smaller than 4μ m and PZT film was continuous, effective d33 evaluated from net longitudinal displacement was smaller than intrinsic d33, because the side PZT film clamped the edge of the capacitor disk and prevented the whole disk from elongating longitudinally. It was also revealed that d33 value calculated from net longitudinal displacement of PZT film depended on the Poisson's ratio of PZT and was not equal to intrinsic d33, excluding the case that φ TE was smaller than 4μ m and PZT film was side-etched. In conclusion, it is suggested that smaller φ TE (< 4μ m, in our case) and side-etch treatment permit a precision measurement of d33; however this condition is difficult to be satisfied experimentally.
Simulation of Phonon-Polariton Generation and Propagation in Ferroelectric LiNbO3 Crystals
Authors: Ward David W. , Statz Eric , Stoyanov Nikolay , Nelson Keith A. 
Published: April 2011

ABSTRACTWe simulate propagation of phonon-polaritons (admixtures of polar lattice vibrations and electromagnetic waves) in ferroelectric LiNbO3 with a model that consists of a spatially periodic array of harmonic oscillators coupled to THz electromagnetic waves through an electric dipole moment. We show that when this model is combined with the auxiliary differential equation method of finite difference time domain (FDTD) simulations, the salient features of phonon-polaritons may be illustrated. Further, we introduce second order nonlinear coupling to an optical field to demonstrate phonon-polariton generation by impulsive stimulated Raman scattering (ISRS). The phonon-polariton dispersion relation in bulk ferroelectric LiNbO3 is determined from simulation.
Electrode effect on microwave properties of ferroelectric (BaxSr1-x)TiO3 thin films
Authors: Kim Won-Jeong , Kim Sang-Su , Song Tae-Kwon , Moon Seung Eon , Kim Eun-Kyoung , Kwak Min-Hwan , Han Seok-Kil , Kim Young-Tae , Ryu Han-Cheol , Lee Su-Jae 
Published: April 2011

ABSTRACTMicrowave properties of coplanar waveguide (CPW) transmission lines fabricated on high dielectric materials, such as ferroelectric Ba1−xSrxTiO3 films, are highly sensitive on the dimension and shape of electrodes. A small change in device dimension affects the total electrical length of the CPW, which may mislead the effective dielectric constant of the dielectric layer. Furthermore, extracting dielectric constant of high-k thin films from the measured microwave properties, such as S-parameters, is very difficult. The well known a modified conformal mapping method frequently exhibits an inconsistent dielectric constant for CPW on high-k materials. CPW transmission lines were fabricated on high-k thin films, ferroelectric Ba0.6Sr0.4TiO3, which were deposited by the pulsed laser deposition with partial oxygen backgrounds. A large phase shift angle of 100° at 10 GHz was observed from the CPW (gap = 4 μm, length = 3 mm) with a 40 V of dc bias, which supports that the idea of the tunable microwave device application using ferroelectrics films. The dielectric constant of the thin ferroelectric film was extracted from the dimension of the CPW (gap, width, length) and the measured S-parameters by a modified conformal mapping. However, the dielectric constant of the ferroelectric thin film calculated by a modified conformal mapping exhibits a gap dependency; dielectric constant (990 ∼ 830) decreases with increasing gap size (4 ∼ 19 μm, respectively). For comparison, dielectric properties have been extracted by extensive EM-simulation using a HFSS™ (Ansoft) with observed dimensions of CPW devices. Total phase, which is closely related with the dielectric constant of the film, is strongly affected by gap size, film thickness, and slanted angle of CPW.
Selection of Materials and Sensors for Health Monitoring of Composite Structures
Authors: Kessler Seth S. , Spearing S. Mark 
Published: April 2011

ABSTRACTEmbedded structural health monitoring systems are envisioned to be an important component of future transportation systems. One of the key challenges in designing an SHM system is the choice of sensors, and a sensor layout, which can detect unambiguously relevant structural damage. This paper focuses on the relationship between sensors, the materials of which they are made, and their ability to detect structural damage. Sensor selection maps have been produced which plot the capabilities of the full range of available sensor types vs. the key performance metrics (power consumption, resolution, range, sensor size, coverage). This exercise resulted in the identification of piezoceramic Lamb wave transducers as the sensor of choice. Experimental results are presented for the detailed selection of piezoceramic materials to be used as Lamb wave transducers.
Coupled Magneto-mechanical Modeling of Composites Containing Aligned Ferromagnetic Particles
Authors: Yin Huiming , Sun Lizhi 
Published: April 2011

ABSTRACTThe objective of this paper is to investigate effective magneto-mechanical behavior of composites containing aligned ferromagnetic particles. The effective magneto-elastic properties and the overall magnetostriction of the composites are derived by considering the pair-wise interaction between ferromagnetic particles. For the composites with soft elastomer matrix, the microstructural configuration rapidly changes with the magnetic and mechanical loads so that the local magnetic and elastic fields are fully coupled. This model accounts for the coupled magneto-elastic interaction and pair-wise interaction between particles. The results show that the Young's modulus along the particle-chain direction is reduced and the shear modulus is increased under the applied magnetic field. Predictions from the proposed model are compared with available experimental data and other models.
High-Dielectric-Constant All-Organic/Polymeric Composite Actuator Materials
Authors: Huang Cheng , Su Ji , Zhang Q.M. 
Published: April 2011

ABSTRACTAmong various electroactive polymer (EAP) actuator materials developed recently, the class of EAPs whose responses are stimulated by external electrical fields (often known as the field type EAPs) is especially attractive due to their high strain level and elastic energy density. However, for most field type EAPs, dielectric constant is low, generally less than 10. Consequently, these polymers usually require high electric fields (>100 V/μm) to generate high elastic energy density which limits their applications. In this paper, we will investigate some avenues to significantly raise the dielectric constant and electromechanical response in field type polymeric materials. By exploiting an all-organic composite approach in which high-dielectric-constant organic particulates were blended with a polymer matrix, a polymeric-like material can reach a dielectric constant higher than 400, which results in a significant reduction of the applied field to generate high strain with high elastic energy density. An all-polymer high-dielectric-constant (K>1,000 @1 kHz) percolative composite material was fabricated by the combination of conductive polyaniline particles (K>105) within a fluoroterpolymer matrix (K>50). These high-K polymer hybrid materials also exhibit high electromechanical responses under low applied fields. In addition, a three-component all-organic composite was designed and prepared to improve the dielectric constant and the electromechanical response, as well as the stability of the composites, in which a high-dielectric-constant organic dielectric phase and an organic conductive phase were embedded into the soft dielectric elastomer matrix.
High Performance P(VDF-TrFE-CFE) Terpolymer for BioMEMs and Microfluidic Devices
Authors: Xia Feng , Klein Rob , Bauer Francois , Zhang Q. M. 
Published: April 2011

ABSTRACTBioMEMs and microfluidic devices have gained a lot of attention in recent years due to their emerging applications in biochemical analysis, medical diagnosis, chemical analysis and synthesis, drug discovery and drug delivery, biosensing and biomimetic systems. The materials requirements for bioMEMs are biocompatible, chemically modifiable, easy to fabricate, economic, compliable and smart. Among various materials, the electroactive polymeric materials can best meet these requirements. Recently, we developed a group of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) based terpolymers which have very high strain level and high energy density. The longitudinal and transverse strain of these materials can reach about –7% and 4.5%, and the elastic energy density is around 1.1 J/cm3, which are very attractive for the development of polymeric pump, valve and other microfluidic components for all polymer-based bioMEMs and microfluidic integrated system. This paper reports on the recent efforts on the optimization of the terpolymer performance and development of microfluidic components using the electroactive terpolymers for bioMEMs.
Effects of Electrode Configurations on Internal Stress Distribution of Multilayer Actuators
Authors: Lee Dong-Kyun , Choi Ji-Won , Han Deuk-Young , Kim Hyun-Jai , Yoon Seok-Jin 
Published: April 2011

ABSTRACTThe internal stress distribution in multilayer actuator was analyzed by a numerical simulation. Around the edge of conventional inter-digital electrodes, the non-uniform electric field generated the stress concentration, which caused the ceramic to crack. Various electrode configurations were presented to decrease this stress concentration. Especially the float electrode type is a promising design because this can be fabricated using almost the same process as the conventional multilayer actuator, and the simulated results indicted that the float electrode type decreased the stress concentration of inter-digital type in approximately 1/3.
Crack Initiation and Growth in a Notched NiTi Shape Memory Alloy Sheet
Authors: Tong Wei , Tao Hong , Zhang Nian 
Published: April 2011

ABSTRACTAn experimental investigation was carried out to study the crack initiation and growth in a single-edge notched NiTi shape memory alloy sheet under tension. It is observed that a crack initiated at the tip of a V-shape notch before the peak axial load was reached and it grew steadily across the width of the NiTi sheet until final fracture. In-plane crack-tip deformation fields at various stages of the crack growth were measured based on an image correlation technique and the crack-tip opening displacement (CTOD) and crack-tip opening angle (CTOA) were subsequently determined. The fracture surface of the NiTi sheet was dimpled based on scanning electron microscopy examinations.
Charge Transfer Dynamics in Single-Wall Carbon Nanotubes Mat: In Situ Raman Spectroscopy
Authors: Gupta S. , Hughes M. , Windle A.H. , Robertson J. 
Published: April 2011

ABSTRACTCarbon nanotubes-based actuator has been investigated using in situ Raman spectroscopy in order to understand the actuation mechanism and to determine associated parameters. We built an actuator from a sheet of single-wall carbon nanotubes (SWNT mat) and studied in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide solutions. Since Raman can detect changes in C-C bond length: the radial breathing mode (RBM) at ∼190 cm-1 varies inversely with the nanotube diameter and the G band at ∼1590 cm-1 varies with the axial bond length, the variation of bonding was monitored with potential. In addition, the intensities of both the modes vary with either emptying/depleting or filling of the bonding and antibonding states due to electrochemical charge injection. We discuss the variation of intensity/frequency providing valuable information on the dynamics of charge transfer on the SWNT mat surface. We found the in-plane microscopic strain (∼ -0.25%) and the charge transfer per carbon atom (fc ∼ -0.005) as an upper bound for the electrolytes used. It is demonstrated that though the present analyses does comply with the proposition made earlier, but the quantitative estimates of the associated parameters are significantly lower if compared with those of reported values for carbon nanotubes. Moreover, the extent of variation (i.e. coupled electro-chemo-mechanical response) does depend upon the type of counter-ion used. The cyclic voltammetry (CV) is also described briefly.
Development of fundamental components for amplification of magneto-surface-acoustic-waves in highly magnetostrictive metal films by means of electron bunching
Authors: Kawahata Takeshi , Obata Naohisa , Nishimura Kazuhiro , Uchida Hironaga , Inoue Mitsuteru 
Published: April 2011

ABSTRACTIn a magneto-surface-acoustic-wave (MSAW) device, phase velocity is controlled by an external magnetic field. We proposed amplification of MSAW with a hybrid structure of FeB amorphous film / InSb semiconductor thin film / LiNbO3 substrate, which is expected to compensate the attenuation of MSAW caused by eddy current loss. In the fabricated MSAW device having the FeB amorphous film with low coercivity and high magnetostrictive, the phase retardation of about 600 degree/cm at magnetic fields of ±300 Oe was obtained. The InSb thin film with a mobility of about 3.5×103 cm2/Vs was obtained by using annealing process. The results show possibility of the MSAW amplification.
Conductance transient comparative analysis of ECR-PECVD deposited SiNx, SiO2/SiNx and SiOxNy dielectric films on silicon substrates
Authors: Castán H. , Dueñas S. , Barbolla J. , Del Prado A. , San Andrés E. , Mártil I. , González-Díaz G. 
Published: April 2011

ABSTRACTA study of metal-insulator-semiconductor (MIS) structures based on SiNx, SiO2/SiNx and SiOxNy films deposited on silicon by electron cyclotron resonance plasma-enhanced chemical vapour deposition (ECR-PECVD) is presented. Interface trap densities measured by deep level transient spectroscopy (DLTS) are higher for silicon oxynitride-based MIS capacitors than for silicon nitride and silicon oxide-silicon nitride-based ones. However, conductance transient analysis demonstrated that Al/SiNx/Si devices exhibit the highest disordered-induced gap states (DIGS) density, whereas the lowest one corresponds to Al/SiNx/SiO2/Si, and silicon oynitride-based MIS capacitors show an intermediate behaviour. In addition, thermal treatments applied to Al/SiOxNy/Si samples reduce DIGS densities to values even lower than those corresponding to Al/SiNx/SiO2/Si devices.
The band alignment problem at the Si-high-k dielectric interface
Authors: Demkov A.A. , Fonseca L.R.C. , Tomfohr J. , Sankey O.F. 
Published: April 2011

ABSTRACTWe investigate the use of the complex band structure of high-k gate dielectrics to estimate their charge neutrality levels, and compute band offsets to Si. Results of these model calculations are then compared to those obtained with direct electronic structure methods and available experiment. It appears that charge neutrality levels thus obtained indeed provide a consistent picture. However, the uncertainty in the conduction band position inherent in the local density approximation may render the theory inadequate for the engineering support. Despite this limitation, linear re-scaling of the charge neutrality levels based on the experimental band gaps has shown excellent agreement with experimental data.
Substrate/oxide interface interaction in LaAlO3/Si structures
Authors: Busani T. , Devine R.A.B. 
Published: April 2011

ABSTRACTAmorphous lanthanum aluminate films (LaAlO3) were deposited on Si substrates at room temperature using rf sputtering in pure Ar or an Ar/O2 mixture with a stoichiometric target. The film composition was analyzed using XPS and EDX. The evolution of the material resulting from annealing at temperatures in excess of 900 °C was studied using infrared spectroscopy, XPS profiling and AFM. We obtain clear evidence for in-diffusion of Si from the substrate into the dielectric film. FTIR analysis showed only one peak centered at 747 cm−1 with an FWHM of 185 cm−1 for as-deposited samples indicating an amorphous structure. Annealed samples showed very narrow absorptions at 483–510, 607, 695–720 and 811 cm−1. No evidence for SiO2 peaks at ∼1060 cm−1 was observed suggesting that the LaAlO3 structure tends not to reduce into a mixture of SiO2 and a silicide. Short time annealing at 1000 °C results in a broad band at 905 cm−1 which can be interpreted in terms of the formation of a layer rich in Si-O-La bonds. Nitridation of the substrate before oxide deposition and annealing slows the degradation process but does not suppress it. X-ray diffraction analysis of the annealed films indicates a very oriented crystalline structure, yet unidentified, whose direction depends upon the orientation of the Si substrate. The dielectric constant in both annealed and as-deposited films was measured to be less than 14 and the leakage current density was very low. Some mobile charge was detected. This dielectric constant is substantially less than the value ∼ 25 anticipated from bulk, single crystal measurements.