bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and Characterization Studies of ABi2ta2o9 (A = Ba, Sr and Ca) Ferroelectric Thin Films
Authors: Das R. R. , Opérez W. , Rodríguez R. J. , Dobal P. S. , Katiyar R. S. , Krupanidhi S.B. 
Published: April 2011

AbstractThin films of ferroelectric ABi2Ta2O9 bismuth-layered structure, where A = Ba, Sr and Ca, were prepared by pulsed laser deposition technique on Pt/TiO2/SiO2/Si(100) substrates. The influence of substrate temperature between 500 to 750°C, and oxygen partial pressure 100-300 mTorr, on the structural and electrical properties of the films was investigated. The films deposited above 650°C substrate temperature showed complete Aurivillius layered structure. Films annealed at 750°C for 1h in oxygen atmosphere have exhibited better electrical properties. Atomic force microscopy study of surface topography shows that the films grown at lower temperature has smaller grains and higher surface roughness. This paper discusses the pronounced influence of A-site cation substitution on the structural and ferroelectric properties with the aid of Raman spectroscopy, X-ray diffraction and electrical properties. The degradation of ferroelectric properties with Ba and Ca substitution at A-sites is attributed to the higher structural distortion caused by changing tolerance factor. A systematic proportionate variation of coercive field is attributed to electronegativity difference of A-site cations.
Oxidation Resistance of TaSiN Diffusion Barriers for Stacked Capacitors
Authors: Letendu F. , Hugon M.C. , Agius B. , Vickridge I , Ayguavives F. , Kingon A.I. 
Published: April 2011

AbstractDue to its resistance to oxidation, TaSiN is a promising candidate as an electrically conductive barrier layer for integration of high permittivity oxides in advanced memory devices. In this study we report on the properties and the resistance to oxidation of TaSiN thin films deposited by reactive magnetron sputtering and processed by rapid thermal annealing (RTA) in 18O2 at 650°C. In order to determine the composition, RBS (Rutherford Backscattering Spectroscopy) and NRA (Nuclear Reaction Analysis) techniques have been used. 18O depth profile concentrations were measured after RTA using the narrow (fwhm=100eV) resonance at 151 keV in the nuclear reaction 18O(p,α)15N.
Process Degradation of a Ferroelectric Capacitor
Authors: Otani Seigen , Tamura Tetsuro 
Published: April 2011

AbstractFerroelectrics used in a memory device such as (Pb,La)(Zr,Ti)O3 (PLZT) are vulnerable to reducing atmosphere and lose remanent polarization easily. In the semiconductor processes, hydrogen gas is generated both from deposition gas of interlayer dielectric and from reaction between metals and moisture in the dielectric. Improving the ferroelectrics resistance to reducing environments is required for the planarization and multi-layer interconnections in future devices. Loss of remanent polarization is related to the imprint properties of the capacitor and can be improved by controlling the deposition condition of sol-gel PLZT and annealing IrOx electrode in oxygen.
Property Improvement of PLZT Capacitor Using CaRuO3 Top Electrode
Authors: Funakubo Hiroshi , Higashi Noriyuki , Okuda Norikazu 
Published: April 2011

AbstractSrRuO3 and CaRuO3 films prepared by MOCVD were compared not only in term of their own properties but for their characteristics as the top electrodes of (Pb, La)(Zr, Ti)O3[PLZT] capacitor, especially for H2 degradation. Resistivity of CaRuO3 and SrRuO3 films increased after heat treatment in H2-containing atmosphere, but was recovered by a heat treatment at 600 °C under O2 atmosphere. When SrRuO3 and CaRuO3 films deposited at 600 °C were used as top electrodes, the remanent polarization(Pr) value of SrRuO3/PLZT/Pt and CaRuO3/PLZT/Pt capacitors were almost the same as the values for capacitors with a Pt top electrode. After a heat treatment in a 3 % H2 atmosphere at 200 °C, followed by one in O2 atmosphere at 450 °C, Pr value was perfectly recovered for both of SrRuO3 and CaRuO3 films. The leakage current become the smallest when using 50 nm-thick CaRuO3 film as a top electrode. Moreover, no degradation was observed for fatigue test up to 1010 cycles when MOCVD-CaRuO3 films were used as top electrodes. These data show that MOCVD-CaRuO3 film with thin thickness is a useful top electrode for PLZT capacitor.
Role of the Electrode Morphology, Thickness and Orientation in the Ferroelectric Performance of Epitaxial Pb(Zr,Ti)O3Thin Films
Authors: Guerrero Cesar , Sánchez Florencio , Roldán José , Güell Frank , García-Cuenca María V. 
Published: April 2011

AbstractA comparison of pulsed laser deposited PbZr0.53Ti0.47O3(PZT) thin film capacitors with SrRuO3(SRO) and LaNiO3(LNO) electrodes on (001) yttria-stabilized zirconia (YSZ) and lattice matched (001) LaAlO3substrates is presented. Both electrode materials allow for the formation of ferroelectric capacitors with large remnant polarization (20-30 μC/cm2) and negligible fatigue, although slight differences arise regarding the promotion of either the rhombohedral or tetragonal phases of PZT. Far more crucial seems to be the tendency of SrRuO3to develop a rougher surface at either small (<30 nm) or large thickness (>100 nm), and on YSZ substrates. In those cases a highly defective and possibly low dielectric interface forms between the electrode and the ferroelectric layer, resulting in greatly degraded ferroelectric performance. LaNiO3is free from these limitations except for the cracks forming at very large thickness (>300 nm), and therefore appears as a more versatile electrode material.
Low-Temperature Growth of C-Axis Oriented Y-Type Hexagonal Ferrite'S Films by Polymerized Complex Method
Authors: Fujii Tatsuo , Komatsu Koutarou , Nakanishi Makoto , Takada Jun 
Published: April 2011

ABSTRACTWell-crystallized Y-type hexagonal ferrite (Me2-Y, Me=Zn and Co) films with highly c-axis orientation were successfully prepared on Ag substrates by dip coating technique. The procedure consisted of preparation of homogeneous metal-organic solution by polymerized complex method, dip coating and subsequent heat-treatment. The films deposited on α-Al2O3 easily reacted with the substrate, while the films deposited on Ag formed hexagonal planar structures. The formation temperature of Me2-Y structures on Ag was 800 °C, which was much lower than that of Me2-Y bulk crystals. The Me2-Y films on Ag had a large in-plane magnetic anisotropy. The observed anisotropy field of the Zn2-Y film was about 13 kOe and that of Co2-Y was too large beyond our experimental limits.
Experimental and Theoretical Investigation into the Dielectric Behaviour of Ferroelectric Thin Film Superlattices
Authors: Gregg J. M. , O'Neill D. , Catalan G. , Bowman R. M. 
Published: April 2011

ABSTRACTPulsed laser deposition has been used to fabricate thin-film capacitor structures in which the dielectric layer is composed of a superlattice of Ba0.8Sr0.2TiO3 and Ba0.2Sr0.8TiO3. The properties of the capacitors were investigated as a function of superlattice periodicity. The dielectric constant was significantly enhanced, and temperature migration of the peak in dielectric constant as a function of frequency was observed, at stacking periodicities of a few unit cells. However, such “relaxor-like’ features were found to be associated with high dielectric loss. Analysis of the imaginary permittivity as a function of frequency showed that fine-scale superlattices conform to Maxwell-Wagner behaviour, indicating that the observed features may be an artefact of increased carrier mobility. Modelling showed that both dielectric enhancement and frequency relaxation could readily be reproduced by Maxwell-Wagner formalism.
Anisotropic Fracture Behavior of Electroless deposited Ni-P Amorphous Alloy Thin Films
Authors: Takashima Kazuki , Ogura Akio , Ichikawa Yusuke , Higo Yakichi 
Published: April 2011

ABSTRACTFracture tests have been carried out for an electroless deposited Ni-P amorphous alloy thin film with different crack growth directions. Cantilever beam type specimens with dimensions of 10 × 10 × 50 μm3 were prepared from a Ni-P amorphous thin film and notches with different directions, which are perpendicular and parallel to the deposition growth direction, were introduced by focused ion beam machining. Fatigue pre-cracks were introduced ahead of the notches. Fracture tests were performed using a mechanical testing machine for micro-sized specimens. Fracture behavior is different between the two types of specimens. As KIC values were not obtained because the criteria of plane strain were not satisfied for this size of the specimen, the provisional fracture toughness KQ values were determined. The KQ value of the specimen with crack propagation direction being perpendicular to the deposition growth direction was 4.2 MPam1/2, while that with crack propagation direction being parallel to the deposition growth direction was 7.3 MPam1/2. This result suggests that the electroless deposited Ni-P amorphous alloy thin film has anisotropic fracture properties.
Nanoindentation of Microspring Thin Films
Authors: Seto Mary W. , Dick Brian , Brett Michael J. 
Published: April 2011

ABSTRACTPorous thin films with helical microstructures were fabricated with the Glancing Angle Deposition technique. These films consisted of arrays of “microsprings” whose geometries could be engineered with nanometer scale control. Some of the mechanical properties of these helically structured films were studied with a nanoindentation technique. Several microscopic “springbed” films were tested over a range of forces using a spherical indenter tip. The geometries of the microsprings were varied, and a number of different materials were used to fabricate these films, which were typically a few micrometers thick. Slanted post arrays, resembling micro-cantilevers, were also subjected to nanoindentation tests. Results of initial experiments, theory, and simulations show that these microstructures behave in a manner analogous to macroscopic springs and cantilevers, and may offer some insight into how materials behave at the microscale.
Double Sided Porous Silicon on Patterned Substrates for Thermal Effect Microsystems
Authors: Périchon S. , Lysenko V. , Remaki B. , Barbier D. 
Published: April 2011

ABSTRACTApplication of porous silicon in thermal microsystem structures often requires the formation of deep localized porous silicon layers. The most commonly used method to prepare the porous layers is the dc anodic etching of monocrystalline silicon in a hydrofluoric acid (HF) based electrolyte. However inhomogeneity of the nanocrystallite size along the layer depth due to the decrease of HF concentration within the pores as well as the poor uniformity of the porous layer thickness limit the elaboration of deep porous layers. Thus we propose an original pulsed anodisation technique, using a double tank etching cell that allows localized porous silicon layers formation throughout the whole wafer thickness.Furthermore a selective double sided pulsed anodisation of silicon was performed on patterned silicon substrates. Porous silicon is formed in pre-determined parts of the wafer using composite polysilicon-silicon nitride masking layers. Technological solutions to get rid of porous layer thickness inhomogeneity due to non uniform current density distribution are discussed. Finally a toric porous silicon layer, crossing the whole silicon wafer, surrounding a 20 mm diameter monocrystalline silicon cylinder was successfully achieved ensuring a new approach of thermal insulation for thermal effect microsystems.
On the Role of the Underlying Microstructure on the Mechanical Properties of Microelectromechanical Systems (MEMS) Materials
Authors: Dirras G. F. , Coles G. , Wagner A. J. , Carlo S. , Newman C. , Hemker K. J. , Sharpe W. N. 
Published: April 2011

ABSTRACTThe microstructure of Low Pressure Chemical Vapor Deposition (LPCVD) Polycrystalline silicon (Polysilicon) thin films was investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and Auger electron spectroscopy (AES). SEM characterization of tensile tested samples showed a brittle like-rupture, along with grooves located at the surface sides of the sample. TEM investigations of as-deposited samples showed equiaxed or fully columnar grains bridging from the bottom to the top of the films. A microstructural coarsening was observed with annealing. In the as-deposited state, the films exhibited a {110} texture as showed by the XRD analysis. The films' top and bottom surfaces were observed to be smooth with a roughness (standard deviation) of about 11nm and 20 nm respectively. A chemical analysis of the thin films showed the presence of carbon and oxygen impurities on the surface and oxygen through the sample as observed in the depth profile. The hypothetical influence of these findings is subsequently discussed in relation to the measured mechanical properties.
Microfabrication of Crevice Corrosion Samples
Authors: Wang Xiaoyan , Kelly Robert G. , Lee Jason S. , Reed Michael L. 
Published: April 2011

ABSTRACTA major challenge in developing computer models for crevice corrosion lies in fabricating appropriate experimental crevice samples. The geometry and dimensions of these samples must be controlled to a high order of precision in order to be amenable for comparison to computational models. In this work we report an effort to construct crevice samples with rigorously defined dimensions by using microfabrication techniques developed for microelectromechanical systems (MEMS). These techniques include microfabrication with SU- 8, electroplating, and other standard semiconductor device fabrication techniques as well. The crevice substrates contain one-dimensional arrays of metal electrodes to be studied, which are isolated by walls of SU-8. The electrodes have individual electrical connections so that spatial information of the in-situ corrosion process can be obtained. The crevice formers with SU-8 posts were coupled to crevice substrates to maintain a uniform crevice gap. Further, crevice formers with regular rectangular subcrevices were fabricated to study the roles of subcrevices in crevice corrosion.
Low Temperature Si Direct Bonding by Plasma Activation
Authors: Cho Yonah , Cheung Nathan W. 
Published: April 2011

ABSTRACTChemical and physical effects of plasma exposed Si wafer pairs were investigated on Si wafer bonding. Oxygen plasma treated Si wafer pairs bonded more strongly at room temperature compared to chemically cleaned, hydrophilic and hydrophobic Si. After 50 hours of annealing at 105°C, the surface energy of the bonded Si pair reached the surface energy of bulk Si (100). X- ray photoemission spectroscopy (XPS) measurements indicated that the exposure of both hydrophilic and hydrophobic Si to oxygen plasma increased a SiO2 like state in the surface layer to a depth of 1.5 nm. Atomic force microscopy (AFM) study showed that plasma irradiation at 300 watts up to 30 seconds did not change surface roughness below 0.5 nm. Exposure to He plasma or N2 did result in enhanced bonding after annealing at 165°C, however, over smaller areas.
Superconductivity and Magnetic Properties of High-Pressure Oxygen Synthesized Ru1−xSr2GdCu2+xO8-z Compounds
Authors: Klamut P.W. , Dabrowski B. , Maxwell M. , Mais J. 
Published: April 2011

ABSTRACTWe report on the new superconducting materials with the formula Ru1−xSr2GdCu2+xO8-z that have been synthesized under high-pressure oxygen conditions. By changing the ratio between Ru and Cu in the compound we were able to increase the temperature of the superconducting transition up to 72 K for x=0.3 and 0.4. Reentrant dependencies of the magnetization found at low temperatures are qualitatively explained assuming a quasi two-dimensional character of the superconducting regions. The magnetic characteristics of these compounds are discussed and compared to the existing data on RuSr2GdCu2O8 magnetic superconductor (Tcon=45K, TN=132 K).
Development of High Critical Current YBCO Coated Conductors By Photo-Assisted MOCVD
Authors: Chen Yimin , Chen Xin , Tang Zhongjia , Chou PenChu , Zhang Xin , Ignatiev Alex 
Published: April 2011

ABSTRACTYBa2Cu3O7 (YBCO) films have been deposited by photo-assisted MOCVD at rates of greater than 0.3μm/min on both single crystal oxide substrates and atomically textured metallic substrates. The YBCO films of thickness from 0.5μm to 3μm deposited on LaAlO3 substrates are shown to be highly atomically ordered with Jc> 1 × 106 A/cm2. CeO2 buffer layers have also been developed by photo-assisted MOCVD for the integration of YBCO with metallic substrates. The CeO2 layers were found to be crack-free when grown on nickel even above 1 micron thickness, and exhibited crystal orientation and in-plane alignment similar to that of the atomically textured Ni substrates. YBCO films grown on the thick CeO2 buffer layers on nickel substrates have shown promising results with Jc∼6 × 105 A/cm2.
Development of LPE process for fabrication of coated conductors
Authors: Izumi Teruo , Hobara Natsuro , Izumi Toru , Hasegawa Katsuya , Kai Masahiko , Fuji Hiroshi , Honjo Tetsuji , Xin Yao , Krauns Christian , Kuznetsov Maxim , Nakamura Yuichi , Shiohara Yuh 
Published: April 2011

ABSTRACTRecent Progress of development for coated conductors by the LPE technique was reviewed. Double layered LPE films were applied to the growth on metal substrates. In both cases of MgO- and NiO- buffers, the constructions were succeeded to grow on Hastelloy and Ni tapes, respectively. In the case of the MgO-buffer, the problem, which is the melting back of the 1st LPE layer during dipping for the growth of the 2nd LPE layer, was found. The problem was solved by means of the selection of the materials for each LPE layer to introduce the difference in the growth temperature for the 1st and the 2nd layers. The lower growth temperature for the 1st LPE layer than that for 2nd one is effective to avoid the problem. On the other hand, the double layered LPE films on Ni tapes revealed Tc of 85K. Concerning the long tape processing, the high growth rate of 1≈ was confirmed even without rotation using the long tape apparatus.
Texture Analysis of Coated Conductors by Micro-Raman and Synchrotron x-ray Diffraction
Authors: Puig Teresa , Puig-Molina Anna , Mestres Narcís , Seijen Harm Van , Alsina Francesc , González Juan C. , Obradors Xavier , Graafsma Heinz , Usoskin Alexander , Freyhardt Herbert C. 
Published: April 2011

ABSTRACTTwo novel complementary and non-destructive techniques for texture analysis of YBCO coated conductors are presented. Micro-Raman (μ-Raman) spectroscopy enables an easy analysis of the film homogeneity by determining the distribution of a- and c-oriented grains within the tape with a 1 μm spatial resolution and acquisition times of 5 min/spot. In addition, synchrotron x-ray diffraction analysis in transmission geometry and 2D detectors enables, with acquisition times of 100 ms, simultaneous observation of a- and c- crystallites and in-plane textures of substrates, buffers and superconducting layer. Thus, opening the field of this technique to in-situ analysis of epitaxial growth of coated conductors prepared by ex-situ processes. Results from these two techniques for stainless steel tapes buffered with IBAD-YSZ and coated with PLD-YBCO are analyzed.
Synthesis and Interface Structure of Sol Gel YBa2Cu3Ox Thin Films for Conductor Development
Authors: Shi Donglu , Xu Yongli , Wang S. X. , Wang L. M. , McClellan Shaun M. 
Published: April 2011

ABSTRACTIn our previous work we have obtained YBCO thick films on silver alloy substrate via the peritectic solidification. To further develop grain-textured YBCO thin films for conductor development, in this study, we have used a sol gel approach to deposit YBCO thin films on two different substrates, namely, yttrium-stabilized zirconia (YSZ) and a silver alloy containing 10 % of palladium (Ag –10%Pd). We have found that the sol gel film on YSZ exhibits an epitaxial growth. This is confirmed by both x-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). XRD data also indicate that the YBCO film on Ag-10%Pd has a c-axis grain orientation. The details are reported on sol gel synthesis and XRD and HRTEM characterization of the YBCO thin films.
Magnetic Imaging of Superconducting Tapes to Determine Current Flow
Authors: Brown G.W. , Hawley M.E. , Foltyn S.R. , Mueller F.M. 
Published: April 2011

ABSTRACTWe have developed a magnetic imaging system that uses magnetoresistive read heads from computer hard disk drives to map the transport-current-induced magnetic field at the surface of superconducting tapes at liquid nitrogen temperature. Transport current pathways are determined from the 2-dimensional magnetic field maps using established inversion schemes. We examined the current flow in pulsed-laser-deposited YBa2Cu3O7-σ films patterned on single crystal SrTiO3 substrates and on a textured yttria-stabilized-zirconia layer deposited on an Inconel ribbon by ion beam assisted deposition. The transport current densities in all cases were consistent with the Critical State Model. For the Inconel-based sample, the transport current density maps have allowed us to observe defects and determine the region that limits the current carrying capacity of the structure.
Tailoring Microstructures Under Strong Non-Equilibrium Conditions: A Feasible Path Towards High JC in Melt Textured YBa2Cu3O7
Authors: Sandiumenge Felip , Plain Jérôme , Puig Teresa , Obradors Xavier , Rabier Jacques , Martínez Maria J. 
Published: April 2011

ABSTRACTMelt textured YBa2Cu3O/Y2BaCuO5 were post processed by high oxygen pressure for different periods and temperatures. This process permits the control of the microstructure, in particular the growth and shape of the stacking faults and thereby the partial dislocation density. Analysis of the Jc(H,T) behavior allow to separate the contribution of Y2BaCuO5 interface from that of dislocations. It is shown that the in-plane partial dislocations act as point-like pinning centers increasing Jc up to 180% but this enhancement factor is counterbalanced by the effect of the stacking faults associated to the partial dislocations.
Modification of Structure and Properties of Superconducting YBaCuO Crystals by Combined Irradiations
Authors: Ibragimova Elvira M. , Kirk Marquis A. 
Published: April 2011

ABSTRACTEffects of electron irradiations in combination with 60Co gamma-quanta on magnetic properties of YBa2Cu3O7−x crystals have been studied to determine the contribution from oxygen defects to the pinning, and the condition of improving the critical parameter, Jc, of the crystals. Irradiation with 300 keV electrons followed by gamma-irradiation makes strong oxygen disorder, causing degradation of SC-transition and appearance of diamagnetic transition at 200 K, but no flux pinning in H>1 Tesla at 77 K. However, it is shown that oxygen defects do contribute substantially to the flux pinning at cation-anion defect clusters in CuO-planes created by moderate fluences of 1 MeV-electrons. A model is suggested for different oxygen and copper defects induced by the irradiations.
High Levitation Force and Trapped Field of Large Grain YBCO at 77K by Ga Doping
Authors: Zhou Yu X. , Lo Wai , Tang Tong B. , Salama Kamel 
Published: April 2011

ABSTRACTLevitation force and magnetic field trapping are the most important properties of YBCO large grain materials. They are dependent on the pinning force exerting on the magnetic flux lines by various crystal defects in YBCO. In this paper, Ga-doped bulk YBCO samples were fabricated by SmBCO seeded melt-growth process. The levitation force and trapped field were enhanced by the introduce of nanometer scale week superconducting regions which are formed by the Ga partially substituting for Cu on the Cu-O chain.