bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Active Ammonia Gas Cracked in Catalytic-CVD on PZT Ferroelectric Capacitors
Authors: Minamikawa Toshiharu , Yonezawa Yasuto , Fujimori Yoshikazu , Nakamura Takashi , Masuda Atsushi , Matsumura Hideki 
Published: April 2011

AbstractWe investigated the effects of exposure to active ammonia (NH3) gas generated by catalytic chemical vapor deposition (Cat-CVD) apparatus on ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) capacitors. It is very important to know these effects in order to apply Cat-CVD SiNx films to passivation films for ferroelectric FRAMs. The exposure to active NH3 was carried out for PZT film capacitors with two types of bottom electrodes on Si wafer at various substrate temperatures. The capacitor with Pt/IrO2 bottom electrode peeled off from substrate during exposure over 200°C. On the other hand, the ferroelectricity of the capacitors with IrO2 bottom electrodes gradually degraded from 200°C to 300°C. As a result, it is found that no degradation of the ferroelectricity is detected for exposure below 200°C. It is concluded that the Cat-CVD method is a promising candidate for preparation of the SiNx passivation film on ferroelectrics, since it is a low stressed film with low hydrogen content.
Reversible and Switching Parts of Polarization in PZT Films
Authors: Petrovsky Vladimir , Anderson Harlan U. , Petrovsky Tatiana , Grishin Alexander 
Published: April 2011

AbstractA pulsing technique was used for more detailed investigation of the switching process in ferroelectric PZT films. This technique allows for the separation of the switching and reversible parts of the polarization and an estimation of the impact of the different effects in the hysteresis loop such as domain structure, depolarizing field and space charge distribution. It is shown that it is possible to provide nondestructive readout of the information stored as the polarization state by measuring the nonlinearity of the reversible polarization. Theoretical limit for the nondestructive readout signal is 20% of the remanent polarization in the differential regime and 12% in the direct regime. The experimental value of the signal is 10% in the both regimes and does not depend on time or the number of readings.
Effects of Grain Boundary on the Ferroelectric Properties of Selectively Grown PZT Thin Films
Authors: Lee Jang-Sik , Park Eung-Chul , Park Jung-Ho , Lee Byung-Il , Joo Seung-Ki 
Published: April 2011

AbstractThe effects of grain boundaries on the characteristics of the PZT thin films using single-grained PZT array by selective nucleation and growth method were investigated by locating the upper Pt electrode of 8 μm× 8 μm sized square directly on the single grains, 1 grain boundary and 4 grain boundaries in a controlled manner. It turned out that when there was no grain boundary, the best ferroelectric and electrical performance were obtained as expected. However, serious degradation was observed in polarization, leakage current, breakdown field and fatigue characteristics when grain boundary was contained in the area measured. This is the first qualitative investigation about the effects of the grain boundaries on the ferroelectric and electrical performance of the PZT thin films. It was found that degradation of the PZT thin films was accelerated with increasing the length of the grain boundaries within the top electrode and the main source of degradation in PZT thin films is grain boundary.
Current Status of Fabrication and Integration of Ferroelectric-Gate Fet's
Authors: Ishiwara Hiroshi 
Published: April 2011

AbstractCurrent status of fabrication and integration of ferroelectric-gate FET's is reviewed. Novel applications of ferroelectric-gate FET's are first discussed, which include a single-transistor-cell-type digital memory, reconfigurable LSI's, and an analog memory for an artificial neural network. In the neural network application, fabrication and basic operation of a pulse-frequency-modulation-type adaptive-learning neuron circuit are described as well as an SOI (silicon-on-insulator)-type FET array for synaptic connection is proposed.Then. data retention characteristics of ferroelectric-gate FET's with MFIS (M : metal, F : ferroelectric, I : insulator (buffer layer), S : semiconductor) and MFMIS structures are discussed. It is shown that the important factors to improve the retention characteristics are (1) increase of the buffer layer capacitance, (2) decrease of the leakage current of both the ferroelectric film and buffer layer, and (3) optimization of the area ratio between the MFM and MIS parts in the MFMIS structure. Based on these considerations, MFMIS-FET's were fabricated using a stacked buffer layer of SrTa2O6/SiON; a current on/off ratio larger than 103 was obtained at a retention time of 10 hours.
Thin Film Decoupling Circuits, Making Use of a Three-dimensional Integration of Thin Film Passive Components
Authors: Klee M. , Löbl P. , Kiewitt R. , Brand W. , van Oppen P. , Lok P. 
Published: April 2011

AbstractIn electronic circuits besides active devices a major part of the components are discrete passive components such as capacitors, resistors and inductors. Especially in the telecommunication circuits, miniaturisation is a major issue. To achieve a high degree of miniaturisation of passive components, thin film processes have been applied. A thin film module for high frequency applications has been demonstrated with a three-dimensional integration of a thin film resistor, a thin film X7R capacitor and a thin film NP0 capacitor processed on top of each other.
Origin of Leakage Current of YMnO3 Thin Films Prepared by the Sol-Gel Method
Authors: Kitahata Hiroya , Tadanaga Kiyoharu , Minami Tsutomu , Fujimura Norifumi , Ito Taichiro 
Published: April 2011

AbstractThe preparation conditions of YMnO3 thin films by the sol-gel method using yttrium alkoxide were optimized to decrease the leakage current of the films. The leakage current of the films was decreased due to the dense microstructure of the films. Moreover, the heat treatment in hydrogen atmosphere and the zirconium doping resulted in a further decrease of the leakage current. The heat treatment in hydrogen atmosphere and the zirconium doping were effective in the decrease of carriers originating in the valence fluctuation of the Mn ions in YMnO3
Photo-Assisted Mocvd Growth of High Dielectric (Ba,Sr)TiO3 Thin Films on Ni/TiN/Si Substrate for Dram Application
Authors: Chen Y. M. , Wu N. J. , Ignatiew A. 
Published: April 2011

AbstractHigh dielectric constant barium strontium titanium oxide (BST) thin films have been deposited on Ni/TiN/Si by photo-assisted metal organic chemical vapor deposition (PhAMOCVD). Planar capacitors based on the Ni/BST/Ni/TiN/Si heterostructure with BST-layer thickness of 50nm exhibited storage densities of about 30 fF/μm2 and leakage current densities of less than 10–7 A/cm2 under bias below 1.8V at room temperature. Nickel as a bottom electrode in this newly designed capacitor structure, can be easily patterned by reactive ion etching, and satisfies the requirement for integration with silicon.
Crystal Structure and Texture Effects on Piezoelectric and Dielectric Properties of PZT Thin Films
Authors: Damjanovic D. , Taylor D. V. , Setter N. 
Published: April 2011

AbstractA systematic investigation of the piezoelectric and dielectric properties of Pb(Zr1-xTix,)O3 (PZT) thin films fabricated by chemical solution deposition was carried out for rhombohedral (x= 0.40), tetragonal (x=0.55) and morphotropic (x=0.47) composition. Each composition was grown with three different crystallographic orientations (textures): “random”, (111) and (100). Nonlinearity (field dependence) of d33 piezoelectric coefficient and dielectric permittivity of the films was studied in detail under subswitching conditions to reveal domain-wall related contributions to the properties. After analyzing for each texture and composition the domain-wall structure, contributions due to domain-wall displacements, and effects of film clamping by the substrate a consistent interpretation of the electro-mechanical properties and nonlinear behavior was proposed. The (100) oriented rhombohedral films show the largest piezoelectric coefficient (intrinsic effect) but limited nonlinearity (domain-wall structure effect) and should therefore be considered as potential candidates for piezoelectric devices.
Properties and Decomposition Behaviors of Reactively Sputtered Pt(O) Electrode Materials
Authors: Saenger K. L. , Rossnagel S. M. 
Published: April 2011

AbstractThe possibility that oxygen-containing Pt might be superior to conventional Pt as an electrode for high-epsilon (HE) and ferroelectric (FE) perovskites has led to renewed interest in the family of Pt(O) materials. Here we report on the properties and decomposition behaviors of reactively sputtered Pt(O)-PtOx electrode materials having x in the range 0 to ∼1.4. Phases of Pt(O) identified included <111>-textured cubic Pt (x < 0.2), tetragonal PtO (x ∼ 1), and amorphous platinum oxide a-PtOx (x ∼ 1.4). Film texture, morphology, resistivity, adhesion, and oxygen content were examined before and after annealing in O2 and N2 at temperatures approximating those of HE/FE deposition and processing (400 - 650°C). After annealing at 650 °C for 5 min, all Pt(O) films lost oxygen and showed growth in metallic Pt phases whose orientations were often <200> or <220> rather than the <111> orientation typically produced by physical vapor deposition of the pure metal. Pt(O) films having a PtO-like structure typically showed only surface oxygen loss, with close to original oxygen levels left in the film bulk, suggesting that the oxygen in these films may be retained long enough to have a beneficial effect on HE/FE layers at later stages in processing.
Optical Properties of a Polyimide for Waveguide Applications in On-Chip Interconnects
Authors: Agarwal N. , Huang X. , Persans P. , Plawsky J. , Ponoth S. , Zhang X. , Murarka S. 
Published: April 2011

AbstractIn this work. we report on characterization methods and the optical properties of a polyimide (Ultradel 9020D). The prism coupling technique was used to couple light into polyimide thin films. The scattered light from the surface was imaged to determine the optical loss at different wavelengths. The coupling angle was used to find the refractive index of the films. The stability of the polymer in terms of refractive index and absorption losses was studied by heat treatment under nitrogen at elevated temperatures. No significant change was observed in the properties of the film at annealing temperatures below 200°C. The bulk and surface losses were separated and it was found that the waveguide losses were dominated by bulk losses. Temperature stability of the polymer was evaluated by annealing the polymer at 125°C for up to 30 hours. No significant changes were seen in the optical losses for these times.
Epitaxial BaTiO3 Thin Films on Different Substrates for Optical Waveguide Applications
Authors: Siegert M. , Lisoni Judit G. , Lei C. H. , Eckau A. , Zander W. , Jia C. L. , Schubert J. , Buchal Ch. 
Published: April 2011

AbstractIn the process of developing thin film electro-optical waveguides we investigated the influence of different substrates on the optical and structural properties of epitaxial BaTiO3 thin films. These films are grown by on-axis pulsed laser deposition (PLD) on MgO(100), MgAl2O4(100), SrTiO3(100) and MgO buffered A12O3(1102) substrates. The waveguide losses and the refractive indices were measured with a prism coupling setup. The optical data are correlated to the results of Rutherford backscattering spectrometry/ion channeling (RBS/C). X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). BaTiO3 films on MgO(100) substrates show planar waveguide losses of 3 dB/cm and ridge waveguide losses of 5 dB/cm at a wavelength of 633 nm.
Real Time Study of Reflective H-PDLC Gratings
Authors: Natarajan L. V. , Sutherland R. L. , Pogue R. T. , Tondiglia V. P. , Tomlin D. , Bunning T. J. 
Published: April 2011

AbstractThe formation of holographic reflection gratings in polymer dispersed liquid crystals(H-PDLC) was investigated in real time both in reflection and transmission modes. Real time study is useful for obtaining information on the speed of grating formation, phase separation dynamics, host polymer shrinkage, polarization dependence of the reading beam, bleaching of the photointiator dye and scattering of the writing beam during grating formation. The real time studies showed that the formation of the grating is fast and reaches a maximum in a few seconds. The diffraction efficiency (DE) VS time curve shows an initial increase followed by a sharp decrease and a recovery to higher efficiencies. Variation of monomer functionality in the pre-polymer syrup resulted in a decrease of reflection efficiency as the functionality is lowered. Varying the writing power of the laser beam gave higher efficiencies at powers exceeding 10 mW/cm2. Liquid crystal (LC) loadings of >16% are needed to obtain measurable efficiencies. Varying the polarization of the probe beam (S vs P) revealed differences in the temporal evolution of DE. Morphology studies are indicative of the differences in the phase separation due to monomer functionality, LC concentration and also laser power. The growth dynamics of H-PDLC gratings are very different from the well known Du Pont photopolymer films which may be due to the phase separation process accompanying gelation in H-PDLC systems.
Optical Limiting with Lithium Niobate
Authors: Cook Gary , Jones David C. , Finnan Craig J. , Taylor Lesley L. , Vere Tony W. , Duignan Jason P. 
Published: April 2011

AbstractIron doped lithium niobate (Fe:LiNbO3) in a simple focal plane geometry has demonstrated efficient optical limiting through two-beam coupling. The performance is largely independent of the total Fe concentration and the oxidation state of the Fe ions, providing the linear optical transmission of uncoated crystals is between 30% and 60%. Fe has been found to be the best dopant for LiNbO3, giving the widest spectral coverage and the greatest optical limiting. Optical limiting in Fe:LiNbO3has been shown to be very much greater than predicted by simple diffusion theory. The reason for this is a higher optical gain than expected. It is suggested that this may be due to an enhancement of the space-charge field arising from the photovoltaic effect. The standard two-beam coupling equations have been modified to include the effects of the dark conductivity. This has produced a theoretical intensity dependence on the ΔOD which closely follows the behaviour observed in the laboratory. A further modification to the theory has also shown that the focusing lens f-number greatly affects the optical limiting characteristics of Fe:LiNbO3. A lens f-number of approximately 20 gives the best results.
Polaronic and Bipolaronic Enhancement of Second Hyperpolarizabilities in Dithienyl Polyenes from Ab Initio Quantum Methods
Authors: Trohalaki Steven , Zellmer Robert J. , Pachter Ruth 
Published: April 2011

AbstractSpangler and He [1,2] have shown that dithienyl polyenes form extremely stable bipolaronic dications when oxidatively doped in solution. Previous theoretical studies applied empirical methods to predict bipolaronic enhancement of hyperpolarizabilities for simple polyenes [3,4]. Here, we employ density functional theory to optimize the gas-phase molecular conformations of neutral, cationic, and dicationic forms of a series of dithienyl polyenes, where the number of ethene units, N, is varied from 1–5. Ab initio Hartree-Fock, generalized valence bond, configuration interaction, and Møller-Plesset calculations demonstrate that the dications are farily well described with a closed shell and therefore have little biradicaloid character. Second hyperpolarizabilities, γ, are subsequently calculated using ab initio Hartree-Fock theory and a finite field methodology. As expected, γ increases with the number of ethene units for a given molecular charge. The cations also show the largest increase in γ with N. For a given value of N, the cations display the largest γ values. However, if we treat the dication as a triplet, which might be present in solution, then it displays the largest γ.
Improved Refractive Index from a Planar Leaky Wave-Guide Coupler
Authors: Liu Tao , Samuels Robert J. 
Published: April 2011

AbstractModal loss coefficients for a planar leaky wave-guide are obtained by two new methods. One is a numerical calculation combining optical thin film theory with optical wave-guide theory; another is an analytical derivation based on analogy to Beer's law. Considering the influence of the modal loss, a modified mode equation for the planar leaky wave-guide is obtained, which greatly increases the accuracy of the refractive index and thickness of the thin film in a planar leaky wave-guide coupler (prism I film I substrate).
Biomimetic Coatings on Orthopedic Implants: a Review
Authors: Groot K. De , Wen H. B. , Liu Yuelian , Layrolle Pierre , Barrere Florence 
Published: April 2011

AbstractIn bone replacement surgery, replacement of joints (of hip, knee, finger and jaw) is a major sub discipline, requiring mechanically strong and biologically compatible, or biocompatible, implants. Since mechanical strength can only be achieved with metals that lack the required biocompatibility, surface treatments to improve that lack have been studied extensively. Since the mineral phase of bone consists of various calcium salts, the most relevant one being (carbonated) apatite, the surface treatments of choice are coatings of such salts on orthopedic implants have been successfully developed. (Bulk ceramics of CaP are too brittle to be used for load bearing implants). Although currently used coatings as obtained by plasma spraying have been highly successful, the high temperature and line-of-sight nature of the plasma spray process prevent (1) coatings to be deposited on implants made of polymer composites, (2) coatings to be deposited on complex surfaces and/or within porous implants and (3) biological molecules such as growth factors or antibiotics to be included in the coating. Therefore, we and several other research groups have focussed our attention to so called biomimetic coatings, that are produced at ambient temperature by a precipitation process from fluids resembling body fluids in their inorganic composition. In this presentation, we will give a review of some current developments on biomimetic coatings.
Mechanism of Apatite Formation on Bioactive Titanium Metal
Authors: Kokubo T. , Kim H.-M. , Takadama H. , Uchida M. , Nishiguchi S. , Nakamura T. 
Published: April 2011

AbstractThe present authors previously showed that titanium metal, which was exposed to 5.OMNaOH solution at 60°C for 24 h and heat-treated at 600°C for 1 h, spontaneously forms a bonelike apatite layer on its surface in the living body, and tightly bonds to the bone through the apatite layer. In the present study, mechanism of the apatite formation on the bioactive titanium metal was investigated in an acellular simulated body fluid (SBF). A thin sodium titanate layer was formed on the surface of the titanium metal by the NaOH and heat treatments. The sodium titanate layer released Na+ ions via exchange with H3O+ ions in SBF, to form a lot of Ti-OH groups on its surface. The Ti-OH groups first combined with Ca2+ ions in SBF, and then later with PO43- ions to form the apatite. Titania and Na2O-TiO2 gels prepared by a sol-gel method as model substances of the sodium titanate layer on the surface of the titanium metal showed that Ti-OH groups of anatase structure are effective for the apatite nucleation, whereas those of amorphous structure and Na2Ti5O11 crystal are not effective.
Fast Formation of Biomimetic Ca-P Coatings on Ti6Al4V
Authors: Barrère F. , Layrolle P. , van Blitterswijk C. A. , de Groot K. 
Published: April 2011

AbstractThe aim of this study was to accelerate the formation of biomimetic Calcium-Phosphate (Ca-P) coatings on Ti6Al4V by using a 5 times more concentrated Simulated Body Fluid (SBFx5) than the regular SBF. The production of SBFx5 was possible by decreasing the pH of the solution to approximately 6 with CO2 gas. The release of this mildly acidic gas allowed the formation of a Ca-P film after 4h of immersion at pH=6.8. The structure of this coating was an amorphous carbonated Ca-P. In addition, our experiments showed that the presence of Mg2+ was absolutely necessary for the Ca-P coating formation on Ti6Al4V substrate. Mg2+ is a crystal growth inhibitor and favored the heterogeneous nucleation. Furthermore, depth profile X-Ray Photoelectron Spectroscopy showed that Ca-P nucleation on the passive Titanium oxide (TiO2) passive layer was initiated by Ca2+ and Mg2+. The attachment of this Ca-P coating resulted probably from chemical bonds such as P-O-Ti and Ca-O-Ti. Ca was more present at the coating/substrate interface than P. Thereby Ca-O-Ti seems to be favored.
Bone Bonding of Biomaterials And Apatite Formation On Biomaterials
Authors: Nakamura Takashi , Neo Masashi , Kokubo Tadashi 
Published: April 2011

AbstractBioactive ceramics are known, which can bind bone tissue chemically. The authors tested bone-bonding strength of biomaterials using detaching test and observed the interface between bone and bioactive ceramics with transmission electron microscopy. An intervening apatite layer was observed at the interface of bone and bioactive ceramics. This layer was distinguished from bone apatite or ceramic. This apatite layer was formed within several days after implantation before bone was observed on the materials. Bisphosphonate is well known to inhibit apatite formation. The injection of bisphosphonate to rabbits concentrationdependently decreased bone-bonding strength of ceramics. The apatite layer was formed on bioactive ceramics in vitro by immersing them in simulated body fluid that contained similar concentrations of inorganic ions as plasma did. Using this apatite layer formed in vitro, it is possible to characterize the apatite layer. This apatite layer enhanced the differentiation of rat bone marrow cells to bone cells in vitro. When osteoclasts were cultured on this layer, they absorbed the apatite layer.These results suggested this apatite layer not only plays a key role for bone bonding but also behaved as bone-like tissues.
Improvements of Apatite-Forming Abilities on Pure and Sodium-Containing Diopside Substrates Using Porous Diopside Thin Films as Nucleating Agent
Authors: Iwata N. Y. , Tsunakawa S. , Tanaka M. , Utsu T. , Matsumoto K. 
Published: April 2011

AbstractPure diopside, CaMgSi2O6 and the partly modified new type of crystalline diopside, NaxCa1-xMgSi2O6, were prepared mainly by coprecipitation process These ceramics were synthesized from the inorganic nitrates and the metal alkoxide in ethanol solutions. The sodium contents in the crystal had remarkable effect on the apparent densities and improved the mechanical properties, especially when the hot-isostatic pressing was applied in the final process. The precise measurements of the X-ray diffraction patterns strongly suggested that the Ca positions in the unit cell were partly substituted by the Na atoms. SBF soaking tests showed that the porous sol-gel method diopside induced the higher apatite crystal growth rates than the hot-pressed surface of the pure or the Na-modified diopside.The surface of the coprecipitation process diopside specimens was coated with the porous ceramics for the purpose of the formation of the bioactive diopside films.