bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Analysis at Low and High Temperature and Evidence of Structural Transition Induced by Praseodymium in SrTiO3
Authors: Durán Alejandro , Morales Francisco , Fuentes Luis , Castro Javier , Siqueiros Jesus 
Published: April 2011

ABSTRACTTo explore the nature of ferroelectric behavior induced by Pr ion in the SrTiO3 ceramic, we brought together a combination of Synchrotron x-ray powder diffraction and thermal analysis. Rietveld analysis shows a clear peak splitting strongly suggesting a cubic-tetragonal structural transition when 15 % Pr substitutes the Sr site. To determine the temperature of the structural instability differential thermal analysis at high temperatures (30-900 °C) and specific heat at low temperatures (2-300 K) were performed. The difference in the heat capacity for Pr doped and undoped samples are very small. A plateau in Cp/T vs T at 110 K is a clear evidence of the competing effect of two kinds of order parameters, one represented by the polarization and the other by the rotation of the oxygen octahedral in the perovskite structure. Upon heating, DTA analysis shows an unexpected single endothermal broad anomaly at about 118 °C. The occurrence of this thermal anomaly could be related to displacive structural contributions providing unambiguous evidence of diffuse phase transition.
Molecular Beam Epitaxial Growth and Dielectric Characterization of Ba0.6Sr0.4TiO3 Films
Authors: Fisher P. , Skowronski M. , Salvador P. A. , Snyder M. , Xu J. , Lanagan M. , Maksimov O. , Heydemann V. D. 
Published: April 2011

ABSTRACTBa0.6Sr0.4TiO3 films were grown by molecular beam epitaxy on MgO(001) and LaAlO3(001) substrates. The growth mode was determined to be two-dimensional by in-situ reflection high-energy electron diffraction. The films were structurally and dielectrically characterized ex-situ using X-ray diffraction, Rutherford backscattering spectrometry, and split cavity resonance mode dielectrometry. The structural and dielectric properties of the Ba0.6Sr0.4TiO3 film grown on MgO were determined to be inferior to the film grown on LaAlO3, as was indicated by the broader rocking curve (0.59 deg. vs. 0.17 deg.) and higher dielectric loss (0.29 vs. 0.12).
Conduction Characteristics of Charge Ordering Type Ferroelectrics,YFe2O4
Authors: Imamura Ken , Horibe Yoichi , Yoshimura Takeshi , Fujimura Norifumi , Mori Shigeo , Ikeda Naoshi 
Published: April 2011

ABSTRACTElectrical conduction properties of charge ordering type ferroelectrics YFe2O4 were investigated. YFe2O4 was synthesized in reduced atmosphere at 1200 °C. Oxygen partial pressure of the reduced atmosphere was controlled by the equilibrium state of CO and CO2. YFe2O4 is paramagnetic at room temperature and has Néel temperature around 250K. The Néel temperature was decreased with increasing the amount of oxygen deficiency. Moreover, YFe2O4 showed ohmic conduction from 260 to 100 K. The temperature dependence of the DC conductivity showed an inflection point at the Néel temperature, which indicated the development of charge ordering of Fe2+ and Fe3+ ions. From the complex impedance measurements, the equivalent circuits of YFe2O4 with different oxygen deficiency were determined at various temperatures.
Evaluation and Modeling of Power Generator with Bimorph PZT Cantilever
Authors: Shen Dongna , Ajitsria Jyoti , Choe Song-Yul , Kim Dong-Joo 
Published: April 2011

ABSTRACTBattery, the traditional power source in present wireless remote sensor systems, has large volume and requires large amount of maintenance. Therefore, piezoelectric power generator has been studied for a potential alternative to battery by scavenging or harvesting energy from its operating environment. The efforts for investigating such piezoelectric device have been especially enhanced by the miniaturization requirement and low energy consumption of advanced devices as well as the sufficient vibration energy sources and its high conversion efficiency. To utilize piezoelectric material as energy conversion transducer, the device should be designed to operate with high efficiency and simple configuration. PZT (Lead Zirconium Titanate) is an excellent candidate for energy conversion because of its large piezoelectric constant and coupling coefficient.In this study, power generators based on bimorph cantilever structure were designed and fabricated using PZT ceramic benders due to accessible large strain or energy. The parameters influencing the output energy of piezoelectric bimorph cantilevers including the dimensions of the cantilever and the proof mass, the loading ways of the proof mass, and the resonant frequency of the cantilever were systematically investigated. The robustness of cantilever structure was also considered for implementing piezoelectric power conversion devices in harsh environments. The final optimal design was realized by considering the balance between the output power and the safety factor through numerical analysis. The energy density generated by the optimized piezoelectric devices was higher than 1 mW at 1-g vibration, which could be enough to operate microsensor systems. To broaden the operation conditions, multiple-resonant frequency device was also explored.
Comparison of Piezoelectric Materials for Vibration Energy Conversion Devices
Authors: Shen Dongna , Choe Song-Yul , Kim Dong-Joo 
Published: April 2011

ABSTRACTPiezoelectric materials have been investigated as vibration energy converters to power wireless devices or MEMS devices due to recent low power requirement of such devices and the development of miniaturization technology. It has shown the potential that piezoelectric power generator can be an alternative to the traditional power source-battery because of facile vibration sources in our environment and the potential elimination of maintenance required for large volume batteries. To date, PZT (Lead Zirconium Titanate) has been commonly exploited as a piezoelectric material for energy conversion since it can generate higher power density even at low-g (< 1 g) vibration environment. Its high fragility, however, can limit its applicability at high-g conditions. Therefore, other types of piezoelectric materials such as polymer and composite are necessary to investigate the applicability at severe vibration conditions. In this study, piezoelectric power generators based on cantilever beam structure were designed, optimized, and fabricated by considering matching the resonant frequency with environmental vibration, achieving maximum output power, and reaching maximum g-value without device failure. As piezoelectric materials, ceramic PZT, polymer PVDF (Polyvinylidene fluoride) and composite MFC (Macro Fiber Composite) were utilized. The energy conversion of all three types of generator devices was systematically evaluated. All three devices were measured to generate enough power density for providing electric energy to wireless sensor or MEMS device. The PZT device shows the highest output energy density and PVDF device has the highest durability to operate at high-g vibration condition.
Peculiar Features of the Dielectric Response in Lead Scandium Tantalate Pb(Sc1/2Ta1/2)O3 Thin Films
Authors: Brinkman Kyle , Tagantsev Alexander , Cherman Vladimir , Wang Yongli , Setter Nava , Kamba Stanislav , Petzelt Jan 
Published: April 2011

ABSTRACTAn examination of the low temperature (20 K) dielectric permittivity revealed dispersion between the MHz and THz frequencies in both disordered and ordered Pb(Sc1/2Ta1/2)O3 (PST) thin films. The difference between the lattice contribution in the THz regime and that measured in the MHz regime at extremely low temperatures points to the peculiar contribution of polar regions which maintain their mobility on cooling. Experiments measuring the permittivity upon cooling under an electric bias field revealed an additional peculiar feature of polar regions in disordered PST thin films: the application of a DC field of 30kV/cm failed to induce a phase transition to a long range polar state.
Simultaneous Observation of Surface Morphology and Dielectric Properties Using Non-Contact Scanning Nonlinear Dielectric Microscopy with Atomic Resolution
Authors: Hirose Ryusuke , Cho Yasuo 
Published: April 2011

ABSTRACTRecently, we have developed Non-Contact Scanning Nonlinear Dielectric Microscopy (NC-SNDM) with a new height-control technique utilizing higher order nonlinear dielectric constant detection (ε(4) signal). In theoretically, NC-SNDM has quite high height sensitivity against the gap between tip and sample as well as STM technique and the simultaneous observation of the topography and ferroelectric polarization (local dipole moment) distribution with atomic resolution has been expected. To confirm such performance of NC-SNDM with atomic resolution, UHV-SNDM was developed and Si(111) cleaned surface was chosen as a specimen. As a result, we have succeeded in observing Si(111) 7×7 atomic structure. Moreover, distribution of tunneling current and lowest order nonlinear dielectric signal ε(3) could be observed simultaneously. To the best our knowledge, this is the first successful demonstration of the atomic resolution achievement in dielectric microscopy techniques.
Microwave Magneto-Electric Interactions in Multiferroics
Authors: Srinivasan Gopalan , Tatarenko A.S. , Fetisov Y. K. , Gheevarughese V. , Bichurin M.I. 
Published: April 2011

ABSTRACTInvestigations on microwave magneto-electric (ME) interactions at 1-10 GHz have been carried out on yttrium iron garnet (YIG)-lead zirconate titanate (PZT) and YIG-lead magnesium niobate lead titanate (PMN-PT) bilayers. Ferromagnetic resonance is a powerful tool for such studies. An electric field E applied to the composite produces a mechanical deformation in PZT or PMN-PT, resulting in a shift in the resonance field for YIG. Information on the nature of high frequency ME coupling has been obtained from data on resonance field shift vs E. A cavity resonator or stripline structure was used. The measured ME interactions are in the range 1-5 Oe cm/kV. The coupling strength has been found to be dependent on magnetic field orientation. The strongest interaction is measured in YIG-PZT systems. The design and characterization of ferromagnetic resonance based, electric field tunable ME resonators and filters are discussed.
The Electronic Structure of 1,7-PCB10H11 Molecular Films
Authors: Balaz Snjezana , Boag Neil M , Platt Neil P , Dimov Dimtcho I , Brand Jennifer I , Dowben Peter A 
Published: April 2011

ABSTRACTThe electronic structure and highest occupied to lowest unoccupied molecular orbital gap of undoped films of the molecular icosahedra of closo-1-phospha-7-carbadodecaborane (1,7-PCB10H11, meta-phosphacarborane) are reported. For 1,7-PCB10H11 adsorbed on Au and Ag, the Fermi level is placed closer to the lowest unoccupied molecular orbital than has been observed with closo-1-phospha-2-carbadodecaborane (1,2-PCB10H11, ortho-phosphacarborane) adsorbed on Au and Ag.
Dielectric Properties of PCB Embedded Bismuth-Zinc-Niobium Films Prepared using RF Magnetron Sputtering
Authors: Lee Seungeun , Lee Jung Won , Lee Inhyung , Chung Yul Kyo 
Published: April 2011

AbstractDielectric properties of bismuth-zinc-niobium oxide (Bi1.5Zn1.0Nb1.5O7, BZN) thin films have been investigated for embedded capacitor. Crystalline BZN has a pyrochlore structure in nature and shows a dielectric constant of ∼ 200 and very low leakage current when crystallized. Since the process temperature is limited to < 200 due to an organic based substrate in printed circuit board, as-deposited BZN film is composed of an amorphous phase, confirmed by XRD analysis. However, it shows remarkably high dielectric constant of 113. It makes BZN to be a proper candidate as a decoupling embedded capacitor in power delivery circuits. Effects of post treatment such as oxygen plasma treatment and low temperature thermal annealing on dielectric properties of BZN thin films are studied. By optimizing deposition conditions, amorphous BZN thin film is well processed in the current PCB process and provides a capacitance density as high as 218 nF/cm2 and leakage current less than 1 μA/cm2 at 3V.
Strategy for the Integration of PLZT Thin Films on Base-Metal Foils for High Voltage Embedded Passives
Authors: Ma Beihai , Balachandran U. , Kaufman David Y , Uprety Krishna 
Published: April 2011

AbstractEvolution of electronic devices towards higher performance and smaller size requires the passive components to be embedded within a printed wire board (PWB). A “film-on-foil” approach is the most viable fabrication method. A high permittivity of lead lanthanum zirconate titanate (PLZT) thin film was coated on nickel foil by chemical solution deposition. Such a prefabricated capacitor sheet can be embedded into a PWB. However, formation of a parasitic low-permittivity interfacial layer of nickel oxide during thermal processing of the PLZT films considerably reduces the capacitance density. To eliminate this parasitic effect, conductive buffer layer of lanthanum nickel oxide (LNO) was coated by chemical solution deposition on nickel foil. We produced PLZT film-on-foil capacitors with capacitance densities as high as 1.5 μF/cm2 and breakdown field strength >1.4 MV/cm. With the desirable volumetric character, PLZT film-on-foil capacitors hold particular promise for use in high voltage embedded passives.
Layered Compound Semiconductor GaSe and GaTe Crystals for THz Applications
Authors: Mandal Krishna C. , Kang Sung H. , Choi Michael K. 
Published: April 2011

AbstractThe single crystal growth of layered semiconductors GaSe and GaTe by vertical Bridgman technique using zone refined selenium (Se), tellurium (Te) and high purity (HP) gallium (Ga) have been described. The grown crystals (2.5 cm diameter and ∼10 cm long) have demonstrated efficient broadband tunable THz emission and as sensitive THz detectors. The crystals have shown promising characteristics with good optical quality, high dark resistivity, wide band gap (GaSe-2.01 eV and GaTe-1.66 eV at 300 K), good anisotropic (parallel, p & perpendicular, pa) electrical properties (σ∥ vs σ⊥ and μ∥ vs σ⊥) and long term stability. Different steps involved in processing GaSe and GaTe crystals as THz sources and sensors are described.
Single-Mode Polymer Optical Fiber Sensors for Large Strain Applications
Authors: Kiesel Sharon M. , Peters Kara , Hassan Tasnim , Kowalsky Mervyn 
Published: April 2011

AbstractThis paper characterizes an intrinsic, single-mode, polymer optical fiber (POF) sensor for use in large-strain applications such as civil infrastructures subjected to earthquake loading or systems with large shape changes such as morphing aircraft. The opto-mechanical response was formulated for the POF including a second-order (in strain) photoelastic effect as well as a second-order (in strain) solution for the deformation of the POF during loading. It is shown that four independent mechanical and opto-mechanical constants are required for the small deformation regime and six additional independent mechanical and opto-mechanical constants are required for the large deformation regime. The mechanical nonlinearity of a typical polymer optical fiber was experimentally measured in tension at various loading rates. The secant modulus of elasticity measured at small strains, roughly up to 2% strain, was measured to be ∼4GPa whereas at larger strains, roughly up to 4.5% strain, the secant modulus was measured to be ∼4.8GPa. As the loading rate was increased the yield strain increased, ranging from ∼3.2% at 1mm/min to ∼5% at 305 mm/min.
CMOS-Compatible Through Silicon Vias for 3D Process Integration
Authors: Tsang Cornelia K. , Andry Paul S. , Sprogis Edmund J. , Patel Chirag S. , Webb Bucknell C. , Manzer Dennis G. , Knickerbocker John U. 
Published: April 2011

ABSTRACTAs the limits of traditional CMOS scaling are approached, process integration has become increasingly difficult and resulting in a diminished rate of performance improvement over time. Consequently, the search for new two- and three- dimensional sub-system solutions has been pursued. One such solution is a silicon carrier-based System-on-Package (SOP) that enables high-density interconnection of heterogeneous die beyond current first level packaging densities. Silicon carrier packaging contains through silicon vias (TSV), fine pitch Cu wiring and high-density solder pads/joins, all of which are compatible with traditional semiconductor methods and tools. These same technology elements, especially the through silicon via process, also enable three dimensional stacking and integration. An approach to fabricating electrical through-vias in silicon is described, featuring annular-shaped vias instead of the more conventional cylindrical via. This difference enables large-area, uniform arrays to be produced with high yield as it is simpler to integrate into a conventional CMOS back-end-of-line (BEOL) process flow. Furthermore, the CTE-matched silicon core provides improved mechanical stability and the dimensions of the annular via allows for metallization by various means including copper electroplating or CVD tungsten deposition. An annular metal conductor process flow will be described. Through-via resistance measurements of 50, 90, and 150μm deep tungsten-filled annular vias will be compared. Two silicon carrier test vehicle designs, containing more than 2,200 and 9,600 electrical through-vias, respectively, were built to determine process yield and uniformity of via resistance. Through silicon via resistances range from 15-40 mΩ, and yields in excess of 99.99% have been demonstrated.
Exploration of the Scaling Limits of 3D Integration
Authors: Pozder Scott , Jones Robert , Adams Vance , Li Hui-Feng , Canonico Michael , Zollner Stefan , Lee Sang Hwui , Gutmann Ronald J. , Lu Jian-Qiang 
Published: April 2011

ABSTRACTThree dimensional (3D) wafer bonding is an emerging technology that may be used to increase transistor densities by stacking devices over devices. The alignment of the wafers and the devices on them is a function of the mechanical capability of the wafer to wafer alignment tool and the thermal conditions of each wafer when bonded. However, as bonded wafers are thinned to 1% or less of their starting thickness the processes of bonding and thinning as well as previous process history affect wafer planarity and silicon stress. The drive to vertically interconnect circuit blocks at the sub-micron scale requires a high density of vertical interconnects and thinning a wafer to less than 5 μm enables through wafer via processing at a scale found in the first layers of the interconnect stack. In this paper the measurement of wafer to wafer alignment was done by comparing a metal pattern on a face down bonded silicon on insulator (SOI) wafer to a complementary metal pattern on the bulk wafer to which it was bonded. The effect of aggressive thinning is evaluated using thinned back to face bonded SOI wafers with functional devices and face down bonded non-patterned SOI wafers thinned after bonding. The face up bonded SOI wafers with functional devices were temporarily bonded face down to a Si-wafer I, thinned to the buried oxide (BOX), face up bonded with benzocyclobutene (BCB) on a Si-wafer II, followed by release of the temporary bond and electrical test. Raman and XRD stress measurements of the non-patterned SOI wafer silicon 70 nm and 110 nm thick SOI Si were taken before and after thinning, and the radius of curvature of the SOI wafers and the bulk wafer substrates was monitored. Thermo-mechanical models of SOI Si stress and bonded wafer curvature are compared to the measured results.
Thermo-Mechanical Reliability of 3D-integrated Microstructures in Stacked Silicon
Authors: Wunderle Bernhard , Mrossko R. , Wittler O. , Kaulfersch E. , Ramm P. , Michel B. , Reichl H. 
Published: April 2011

ABSTRACTThis paper investigates the thermo-mechanical reliability of inter-chip-vias (ICV) for 3D chip stacking after processing and under external thermal loads relevant for the envisaged field of application (mobile, automotive) by Finite Element simulation. First the materials are characterised by nano-indentation to determine elasto-plastic data. Finite Element simulations are used to reproduce these data and to extract local material properties like E-modulus and yield stress. Accumulated plastic strain is used as failure indicator under periodic thermal loading of an ICV. Geometrical, material and process-related parameters are varied to obtain first design guidelines for this new technology. The locations of stress and strain accumulation are given.
Three-Dimensional Integration of Silicon Chips for Automotive Applications
Authors: Weber Werner 
Published: April 2011

ABSTRACTCurrently, 3D integration of semiconductor chips is introduced into high-volume products. While memory and communication will be leading fields of application, automotive will require specific non-standard solutions some of which are in research or development whereas others have already been introduced to production. This paper elaborates on the different opportunities and constraints of automotive applications, presents different technological options and discusses specific solutions considered in research or found in already existing products.
Current and Future Three-Dimensional LSI Integration Technology by “chip on chip”, “chip on wafer” and “wafer on wafer”
Authors: Bonkohara Manabu , Motoyoshi Makoto , Kamibayashi Kazutoshi , Koyanagi Mitsumasa 
Published: April 2011

ABSTRACTRecently the development of three dimensional LSI (3D-LSI) has been accelerated and its stage has changed from the research level or limited production level to the investigation level with a view to mass production. This paper describes the current and the future 3D-LSI technologies which we have considered and imagined. The current technology is taken our Chip Size Package (CSP) for sensor device, for instance. In the future technology, there are the five key technologies are described. And considering con and pro of the current 3D LSI stacked approach, such as CoC (Chip on Chip), CoW (Chip on Wafer) and WoW (Wafer on Wafer), We confirmed that CoW combined with Super-Smart-Stack (SSS™) technology will shorten the process time per chip at the same level as WoW approach and is effective to minimize process cost.
Low Temperature Copper-Nanorod Bonding for 3D Integration
Authors: Wang Pei-I , Karabacak Tansel , Yu Jian , Li Hui-Feng , Pethuraja Gopal G. , Lee Sang Hwui , Liu Michael Z. , Lu J.-Q. , Lu T.-M. 
Published: April 2011

ABSTRACTWafer bonding is an emerging technology for fabrication of complex three-dimensional (3D) structures; particularly it enables monolithic wafer-level 3D integration of high performance, multi-function microelectronic systems. For such a 3D integrated circuits, low-temperature wafer bonding is required to be compatible with the back-end-of-the-line processing conditions. Recently our investigation on surface melting characteristics of copper nanorod arrays showed that the threshold of the morphological changes of the nano-rod arrays occurs at a temperature significantly below the copper bulk melting point. With this unique property of the copper nanorod arrays, wafer bonding using copper nanorod arrays as a bonding intermediate layer was investigated at low temperatures (400 °C and lower). 200 mm Wafers, each with a copper nanorod array layer, were bonded at 200 – 400 °C and with a bonding down-force of 10 kN in a vacuum chamber. Bonding results were evaluated by razor blade test, mechanical grinding and polishing, and cross-section imaging using a focus ion beam/scanning electron microscope (FIB/SEM). The FIB/SEM images show that the copper nanorod arrays fused together accompanying by a grain growth at a bonding temperature of as low as 200 °C. A dense copper bonding layer was achieved at 400 °C where copper grains grew throughout the copper structure and the original bonding interface was eliminated. The sintering of such nanostructures depends not only on their feature size, but also significantly influenced by the bonding pressure. These two factors both contribute to the mass transport in the nanostructure, leading to the formation of a dense bonding layer.