bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and Optical Properties of PbTiO3 Grown on SrTiO3 Substrates by Peroxide MBE
Authors: Izyumskaya Natalia , Avrutin Vitaliy , Gu Xing , Ozgur Umit , Kang Tae Dong , Lee Hosun , Smith David John , Morkoc Hadis 
Published: April 2011

ABSTRACTLead titanate (PbTiO3), a ferroelectric material with perovskite structure, has received a great deal of attention owing to a unique combination of its piezoelectric, pyroelectric, dielectric, electo- and acousto-optic properties [1–3]. PbTiO3 is a very attractive material for the use in a wide variety of fields, including ultrasonic sensors, infrared detectors, electro-optic modulators, and ferroelectric random access memories. To harness the intrinsic properties of PbTiO3 for device applications, however, high-quality epitaxial films are required. PbTiO3 thin films have been prepared by various methods such as chemical vapor deposition, rf magnetron sputtering, pulsed laser deposition, hydrothermal method, and sol-gel technique. Surprisingly, molecular beam epitaxy (MBE), with its precise control over composition, has not been widely applied, except of a few reports on MBE growth with the use of ozone as an oxidizing agent [4]. In the present work, high-quality single-crystal PbTiO3 layers were grown on (001) SrTiO3 substrates by MBE with the use of hydrogen peroxide as an oxidant [5]. Phase composition as well as structural and optical properties of the films were examined as a function of growth parameters by high-resolution x-ray diffractometry, spectroscopic ellipsometry, and photoluminescence. It was found that single-phase PbTiO3 films grew epitaxially at substrate temperatures above 600°C, whereas layers grown at lower temperature contained lead oxide inclusions. All the PbTiO3 layers were c-axis oriented with the epitaxial relationship PbTiO3(100)//SrTiO3(100) and PbTiO3[001]//SrTiO3[001]. No evidence of a-domains was found. Full width at half maximum of (001) rocking curves for 50–60 nm thick PbTiO3 layers are as low as 6–8 arcmin, indicating their good crystal quality. Pseudodielectric function of PbTiO3 was measured using variable angle spectroscopic ellipsometry at room temperature. Refractive index was found to be 2.605 at 633 nm (1.96 eV), which is consistent with the literature data. With the help of the standard critical point (SCP) lineshape analysis the band gap energy was calculated to be (3.778±0.005) eV.
Structural and Ferroelectric Properties of Bi4-xNixTi3O12 Thin Films by Sol-Gel Process
Authors: Melgarejo Ricardo , Tomar Maharaj S , Singhal Rahul , Katiyar Ram S 
Published: April 2011

ABSTRACTNickel-substituted Bi4Ti3O12 (i.e., Bi4-xNixTi3O12) were synthesized by sol-gel process for different compositions. Thin films were deposited on Pt (i.e., Pt/TiO2/SiO2/Si) substrate by spin coating. Materials were characterized by x-ray diffraction and Raman spectroscopy. This study indicates that the material makes a solid solution for the compositions: x = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.30, where a Ni ion replaces the Bi site. The prominent effect of Ni substitution was observed in low-frequency Raman modes. Sol-gel derived thin films of Bi4-xNixTi3O12 on a Pt substrate and post annealed at 700°C were tested for ferroelectric response which showed high remnant polarization (Pr = 22 μC/cm2 for x = 0.15). The leakage current (less then 10−7 A/cm2) at low field was observed in the film with composition x = 0.15 .The polarization of the BNiT (x = 0.15) film decreased to 83% of the initial value after 1×109 switching cycles These results indicate the potential application of Ni substituted bismuth titanate films in non-volatile ferroelectric memories.
Growth of High-Quality Pb(ZrxTi1-x)O3 Films by Peroxide MBE and Their Optical and Structural Characteristics
Authors: Izyumskaya Natalia , Avrutin Vitaliy , Gu Xing , Ozgur Umit , Xiao Bo , Kang Tae Dong , Lee Hosun , Morkoc Hadis 
Published: April 2011

ABSTRACTThe growth of Pb(ZrxTi1-x)O3 (PZT) films by molecular beam epitaxy was demonstrated. Single-crystal, single-phase PZT films were grown on (001) SrTiO3 substrates at a growth temperature of 600°C. In situ monitoring of the growth process by reflection high-energy electron diffraction revealed two dimensional growth for the PZT constituent ternaries, namely, PbTiO3 and PbZrO3, and three-dimensional growth for PZT films of intermediate compositions. Layer-by-layer growth of PZT films, however, was achieved by using a PbTiO3 buffer layer between the SrTiO3 substrate and PZT films. Optical properties of the films of the end ternaries were investigated by spectroscopic ellipsometry. Refractive index at 633 nm was found to be 2.66 for PbTiO3 and 2.40 for PbZrO3. Band gap energies of PbTiO3 and PbZrO3 were determined as 3.81 and 3.86 eV, in good agreement with theoretically calculated values. The P-E hysteresis loop of a 70-nm-thick PZT film was well saturated and had a square shape. The remanent polarization and the coercive field were 83 μC/cm2 and 77 kV/cm, respectively, which are respectable.
Long Term Retention Characteristic of Small Inverted Dots Formed on Congruent Single-Crystal LiTaO3
Authors: Cho Yasuo , Odagawa Nozomi 
Published: April 2011

ABSTRACTTo investigate the long-term retention characteristics of a ferroelectric-data-storage system, 80-nm-thick congruent LiTaO3 plates with inverted-domain dot arrays composed of 100-nm-φpdots were baked at 220, 250, 280 and 300°C. After heat treatment over a range of different time intervals, the dots shrank. From the change in the dot radius data, the activation energy (Ea) and frequency factor (α), parameters of the Arrhenius equation, were determined to be = 0.76 eV, = 2.21×105. From these parameter we can predict competitive retention characteristics compared with general memory devices. The phenomenon of dot shrinking can be explained from the energy transition of the system based on wall energy.
Characterization of Alumina Optical Waveguides Grown by Ion Beam Assisted Deposition for SPARROW Biosensors
Authors: Poloju Praneetha , Samudrala P. K. , Nightingale J. R. , Korakakis D. , Hornak L. A. 
Published: April 2011

ABSTRACTDielectric optical films with minimal surface roughness are required for biosensing applications since the coupling characteristics often used in signal transduction are dependent on the quality of the waveguides. This paper describes the fabrication and characterization of alumina-based optical waveguides for biosensor device for biomolecular detection. Alumina (Aluminum Oxide) Al2O3waveguides were chosen for their moisture stability and refractive index. Planar alumina optical waveguides were deposited on Borofloat substrates by a vacuum evaporation process using an ion assisted electron beam deposition technique. The deposited films showed RMS roughness of 0.3nm – 0.5nm and a range of refractive indices varying from 1.62 to 1.654 as a function of varying ion beam parameters such as oxygen flow rates and drive currents. The propagation losses for the TE0(Transverse Electric) mode of the alumina films at 632.8nm wavelength were found to vary between 2dB/cm – 6dB/cm at a wavelength of 632.8nm for TE0polarization as a function of ion beam parameters. It is shown that these factors influence the optical film quality and hold the potential for achieving further waveguide performance improvement for biosensing applications.
Massive Spalling of Intermetallic Compound in Lead-Free Solder Joints
Authors: Yang Su-Chun , Ho Cheng-En , Chang Chien-Wei , Kao C Robert 
Published: April 2011

ABSTRACTSpalling of intermetallic compounds in a massive scale has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a common mechanism based on thermodynamic arguments is proposed to explain this rather peculiar phenomenon that occurs across several systems. According to this mechanism, two necessary conditions must be met. This first is that the most reactive element must be present in a limited amount, and the second is that the soldering reaction must be very sensitive to the concentration of this element. With the growth of intermetallic, more and more of the most reactive elements are extracted out of the solder and incorporated into intermetallic. As the concentration of this element decreases, the local equilibrium phase at the interface changes. This changing of the equilibrium phases caused the non-equilibrium phase to spall.
A Novel PPF Technique--Sn-PPF: Effects of In-Situ Formation Cu-Sn-Ni Intermetallic Nano-Layer on Electronic Packaging Performances
Authors: Liu Lilin , Fu Ran , Liu Deming , Zhang Tongyi 
Published: April 2011

ABSTRACTA novel preplated leadframe (PPF), i.e. Sn-PPF, is developed by electrodepositing a 3∼4nm thick Sn layer between the Cu base leadframe and the Ni plating. The nano-thick intermetallic compound (IMC) layer forms automatically through interdiffusion and reaction between Cu, Ni and Sn. High resolution transmission electron microscopy (HRTEM) observation reveals crystallography relationship between the IMC and Cu base. A drastic reduction of Cu out-diffusion is confirmed by an EDX based oxidation test carried, indicating a significant enhancement in the protection of the leadframe against oxidation and corrosion attack. The Cu diffusion coefficients in the IMC layer were estimated to be about at 250°C and m2/s at 300°C. Results of the wire pull test, the solderability test and the bending test exhibit Sn-PPF's quality with a Ni layer less than 200nm satisfying industrial requirements.
Factors Affecting the Mechanical Properties of Cu/Electroless Ni-P/Sn-3.5Ag Solder Joints
Authors: Kumar Aditya , Chen Zhong , Wong C. C. , Mhaisalkar S. G. , Kripesh Vaidhyanathan 
Published: April 2011

ABSTRACTThis work investigates the factors that affect the mechanical properties of Cu/electroless Ni-P/Sn-3.5Ag solder joints. For the investigation, solder joints were tensile tested after solid-state aging at different temperatures for various durations. Several factors, such as the growth of interfacial compounds (IFCs), Ni3Sn4 morphology, the accumulation of spalled Ni3Sn4 intermetallic particles at the solder/Ni3Sn4 interface, and the formation of Kirkendall voids at the Ni3P/Cu interface, are found to deteriorate the mechanical properties of the joints. Among all these factors, the formation of a layer of Kirkendall voids at the Ni3P/Cu interface, which is a result of Cu diffusion from the interface, causes the most severe decrease in tensile strength with a brittle fracture at the Ni3P/Cu interface. This layer of Kirkendall voids remains the main cause of brittle failure even after the transformation of the Ni3P layer into a Ni-Sn-P layer.
Time-Lapse Measurements of Creep in Au-Sn Die Bonds
Authors: Marinis Ryan , Klempner Adam , Hefti Peter , Pryputniewicz Ryszard , Marinis Thomas , Soucy Joseph 
Published: April 2011

ABSTRACTGold-tin braze is the preferred material for attaching high-precision MEMS inertial sensors within hermetic ceramic packages. The bonds can be made at relatively low temperatures, are mechanically robust, and outgas at very low rates in vacuum sealed packages. There is one significant limitation to Au-Sn bonds, however. The thermal expansion coefficients of MEMS die and ceramic packages are not perfectly matched and temperature gradients occur when the assembly is cooled after brazing. As a result, there is considerable residual stress in the bonded assembly, which is accommodated to some extent by distortion of the sensor die. Over time, as these stresses relax, the distortion of the die changes, which causes the spacing between elements of the integral MEMS sensor to change as well. An important element of sensor-package design is insuring that stress relaxation effects do not cause the instrument to drift beyond its performance specification limits over a typical lifetime of 20 years.Even though Au-Sn has been used for decades to attach silicon chips to ceramic substrates, there is little data available, particularly at low temperatures. An oven, with a specially designed window, allowed in-situ measurements to be made as a function of temperature, joint thickness and load stress. Additionally, a MEMS device brazed to a package with Au-Sn has been measured interferometrically over time to quantify die distortion in a packaged application.
Investigation of Ultralow Loss Interconnection Technique for LTCC based System-in-Package(SIP) Technology at 60GHz
Authors: Kim Dong-Young , Mun Jae Kyoung , Jun Dong-Suk , Kim Haechoen 
Published: April 2011

AbstractThe effects of wire and ribbon bond interconnection on the transmission characteristics at millimeter wave frequency range was presented. The insertion loss and return loss was closely related with the ratio of the signal line width to that of bonded wire or ribbon. The most promise condition for low loss interconnection was that the width of bonded wire or ribbon should be compatible to the width of signal lines. In the actual fabrication of LTCC amp module, the insertion loss of packaging is very small which means that the loss due to bonding is nearly negligible. However, the S11 and S22 degraded severely due to the difference of the types of transmission lines between chip and packaging module. A new transition structure was introduced in order to compensate this difference of transmission lines.
Silicon Through-hole Interconnection for 3D-SiP Using Room Temperature Bonding
Authors: Tanaka Naotaka , Yoshimura Yasuhiro , Naito Takahiro , Akazawa Takashi 
Published: April 2011

ABSTRACTIn rapidly growing market sectors, such as mobile information devices, SiP technology, in which multiple LSI chips are stacked three-dimensionally, is attracting attention as a means of greatly reducing the mounting area of electronic components to improve system performance while reducing system size. Hitachi, Ltd. and Renesas Technology developed a new way to interconnect stacked chips using through-hole electrodes with a lower cost and shorter turn around time (TAT). Stacked chips are electrically interconnected by simply applying a compressive force at room temperature to a conventional chip with multiple gold stud bumps. Gold stud bumps on the upper chips are pressed into the through-hole electrodes on the lower chips by applying a compressive force, which causes plastic to flow into the gold bump. That is, the use of a gmechanical caulkingh technique makes possible electrical connections between stacked chips at room temperature. Compared with conventional through-hole electrode interconnection (more than 200°C), this new method drastically reduces the production cost and the environmental load. By using this technology, the package thickness can be 1.0 mm or less even in ten-chip layers, compared with two-chip layers using wire bonding, which are approximately 1.25-mm thick.
Active Si Interposer : Combination of Through-Si Vias and Redistribution
Authors: Hara Kazumi , Hashimoto Nobuaki , Ito Haruki , Yokoyama Yoshihiko , Imamura Tsuyoshi 
Published: April 2011

ABSTRACTActive Si Interposers (ASI), which are device chips with through Si vias (TSVs) and redistribution wirings, are the focus of this study. A feature of the module is that the redistribution layer includes a stress buffer layer so that stress can be alleviated when it is mounted on a motherboard. For the purpose of this study, it was decided to conduct the process from the backside of the wafer for efficiency of production. One feature of this process is that a device wafer was processed with a glass wafer supported throughout the TSVs' process in order to facilitate process of a thin wafer. However, the maximum temperature of each process was limited. We addressed this problem by the optimization of some of the equipment and the modification of the adhesive that attaches the device wafer to a glass wafer. Finally, a module that was a combination with the ASI and a certain device operated normally. In the last part of this study, the results of the evaluation that studied the impact on the devices of the TSVs' process are presented.
Grinding and Mixed Silicon Copper CMP of Stacked Patterned Wafers for 3D Integration
Authors: De Munck Koen , Vaes Jan , Bogaerts Lieve , De Moor Piet , Van Hoof Chris , Swinnen Bart 
Published: April 2011

ABSTRACT3D integration promises to reduce system form factor through direct stacking and interconnection of chips made using different technologies, into a single system. In our case, these interconnects consist of small and deep through wafer vias in the form of Cu nails. One of the enabling technologies to achieve 3D stacks, is thinning on carrier. It involves backside grinding and CMP of patterned wafers down to 20 micron, while temporarily glued to a carrier.Success of grinding on carrier is found to strongly depend on temporary glue layer properties and bonding quality. Voids in between device wafer and carrier of various origins were observed to cause thin wafer delamination and catastrophic breakage when grinding down below 50 micron. By improvements in the bonding process, we eventually enabled uniform bonding, compatible with standard grinding and CMP techniques.CMP both removes grinding-induced damage and exposes the Cu nails at the thin wafer backside. The developed CMP consists of 2 steps which are optimized to reduce Cu smearing and within-die uniformity. Both are found to correlate with the local Cu nail density variations.
Relations between Microstructure of Mg/Cu Super-laminates and Kinetics of Hydrogen Absorption/desorption
Authors: Tanaka Koji , Takeichi Nobuhiko , Tanaka Hideaki , Kuriyama Nobuhiro , Ueda Tamotsu T. , Tsukahara Makoto , Miyamura Hiroshi , Kikuchi Shiomi 
Published: April 2011

ABSTRACTSuper-laminates have been attracting attention since co-authors Ueda et al. reported that Mg/Cu super-laminates showed reversible hydrogenation and dehydrogenation at 473K. The Mg/Cu super-laminates were prepared by a repetitive fold and roll method. Initial activation at 573 K led the super-laminates to absorb hydrogen at 473K. TEM observations of micro/nano-structures in the super-laminates were performed in order to clarify the process of hydrogenation and dehydrogenation at 473K, The as-rolled Mg/Cu super-laminates have laminated structures in size of sub-micrometer thickness composed of Mg and Cu layers with dense lattice defects. The super-laminates after initial activation keep laminated structure and have uniformly distributed pores with a sub-micrometer diameter. It is considered that these micro/nano-structures of Mg/Cu super-laminates lead to lower dehydrogenation temperature and better kinetics, which would contribute to achieve high performance hydrogen storage materials.
Microstructure of the MgH2 Synthesized by Hydriding Chemical Vapor Deposition
Authors: Saita Itoko , Akiyama Tomohiro 
Published: April 2011

ABSTRACTIt is hardly achieved to prepare highly pure MgH2 by the conventional method of solid-gas reaction between solid magnesium and hydrogen; therefore, we proposed and succeeded to synthesize MgH2 by Hydriding Chemical Vapor Deposition (HCVD). Very interestingly, the HCVDed MgH2 was made of single crystals with fibrous figures; however, further detail of the HCVDed product had not been studied. Therefore the aim of this study was to examine the HCVDed MgH2 in hydrogen storage and to observe the microstructure of the HCVDed MgH2 after the hydrogen desorption and absorption.As the results of Pressure-Composition-Isotherm (PCT) measurement, the HCVDed MgH2 reversibly absorbed and desorbed 7.6 mass% hydrogen, as much as the theoretical maximum hydrogen capacity of magnesium, without any activation treatment. The equilibrium pressure was slightly lower than the reported value. Before and after the PCT measurement, the HCVDed MgH2 did not showed noticeable difference in figure; however, MgHx, which was prepared dehydriding the HCVDed MgH2 in the PCT, showed significant difference in figure: It had zebra stripes in the SEM observation. This observation showed that the hydrogen storage and release went in the radious direction and the hydrogen diffusion was no more rate-limiting. The phase boundaries of Mg and MgH2 involving strain should affected on the plateau pressure in PCT.
Mixed Conductivity and Oxygen Permeability of (BaxSr1-x)0.98Fe1-yMyO3-&[delta] ( x = 0.1-0.3, y = 0.1-0.4 and M = Ga, Al )
Authors: Yong Kang Chun , Kusaba Hajime , Einaga Hisahiro , Teraoka Yasutake 
Published: April 2011

AbstractSubstitution effects of Ga and Al for Fe in (BaxSr1-x)0.98FeO3-δ were studied with respect to crystal structure, conductivity and oxygen permeability. The solubility limits of Ga and Al in (BaxSr1-x)0.98Fe1-yMyO3-δ (M=Ga, Al) were between 20 and 30 mol%. The substitution of Ga and Al caused decreases in electronic and oxide ionic conductivities (mixed conductivities) but the enhancement of the reduction tolerance. Sintered membranes of the Ga- and Al-substituted oxides showed oxygen permeability under the He/air oxygen partial pressure gradient and were stable under the condition of methane partial oxidation at 900 °C.
Processing and Characterization of Sc2O3-CeO2-ZrO2 Electrolyte Based Intermediate Temperature Solid Oxide Fuel Cells
Authors: Zevalkink Alexandra , Hunter Allen , Swanson Matthew , Johnson Christopher , Kapat Jayanta , Orlovskaya Nina 
Published: April 2011

AbstractScCeZrO2 ceramic powders produced by two different manufacturers have been used for the manufacturing of ScCeZrO2 electrolyte based solid oxide fuel cells. Thin, porous anode and cathode layers have been deposited on 150 μm thick, dense electrolyte tapes. Preliminary electrochemical testing of the cells has been performed.
Assembly of Decavanadate Polyanions by Collagen Helices: Synthesis of an Hybrid Inorganic-Bioorganic Mmaterial
Authors: Marchal Axel , Steunou Nathalie , Mosser Gervaise , Coradin Thibaud , Maquet Jocelyne , Livage Jacques 
Published: April 2011

AbstractVanadium oxide-collagen hybrid nanocomposites were prepared by adding a V2O5 sol to a dilute collagen solution. 51V MAS NMR spectroscopy shows that the inorganic phase is composed of the decavanadate [H2V10O28]4− polyanion and V2O5 ribbon-like particles. The broadening of the 51V signals and the absence of Bragg peaks in the XRD pattern suggest a strong disorder concerning the organization of the V2O5 particles and of the decavanadate species in the composites. Analogous hybrid nanocomposites were obtained with a solution that contains only the decavanadate species, showing that the cohesion in the hydrid material results mainly from electrostatic interactions between decavanadate [H2V10O28]4− polyanions and positively-charged collagen helices.
Electrochemical Synthesis of Lamellar Structured Inorganic Films Using Interfacial Surfactant Templating
Authors: Choi Kyoung-Shin , Steinmiller Ellen M. P. , Yarger Matthew S. 
Published: April 2011

AbstractZinc oxide and cobalt hydroxide films with ordered lamellar structures were electrochemically produced via interfacial surfactant templating. This method utilizes interfacial amphiphile assemblies on a working electrode as a template to electrodeposit inorganic nanostructures. Surfactants with anionic head groups (e.g. sodium dodecyl sulfate, 1-hexadecanesulfonate sodium salt, dodecylbenzenesulfonate sodium salt, and dioctyl sulfosuccinate sodium salt) formed bilayer assemblies with Zn2+ and Co2+ ions on the working electrode and guided the lamellar growth of ZnO and Co(OH)2 films. In order to gain the ability to precisely tailor inorganic lamellar structures, the effect of co-solvent and type of working electrode on the repeat distances, homogeneity and orientation of the interfacial amphiphilic bilayers were investigated. The results described here will provide a useful foundation to design and optimize synthetic conditions for electrochemical construction of inorganic lamellar structures.