bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation Of Single-Wall Carbon Nanotubes Forrest Assemblies On Metal Surfaces
Authors: Chattopadhyay Debjit , Galeska Izabela , Papadimitrakopoulos Fotios 
Published: April 2011

ABSTRACTLearning how to purify and manipulate single wall carbon nanotubes (SWNTs) presents a unique challenge in material science. The processing-related difficulties of these long nano-fibers stem from their high aspect ratio, rigidity and the profound hydrophobic attractions along their tubular walls. Shortening them into discrete segments, with lengths from tens to hundreds of nanometers, presents a viable methodology to alleviate the shape-induced intractability. In addition, the metal-assisted self-organization of these nanosized objects into nano-forest geometries with dense perpendicular surface grafting, demonstrates that such nanosized objects hold significant promise for the development of nanoscale devices. This paper will present an extensive characterization of the topological characteristics of these assemblies, along with their surface coverage, growth characteristics and height fluctuation on iron hydroxide substrates.
Electric field and Charged Molecules Mediated Self-Assembly for Electronic Devices
Authors: Lee Sang Woo , McNally Helen A. , Bashir Rashid 
Published: April 2011

AbstractIn this paper we present techniques, utilizing dielectrophoresis and electrohydrodynamics, which can possibly be used for assembling devices suspended in a solution onto a binding site on a substrate. We explored the concepts using micro-scale negatively charged polystyrene beads and rectangular silicon blocks. Dielectrophoretic forces on devices in buffer solutions were examined as a function of frequency of the applied AC signal. The observed results can be explained by taking in account electro-thermal and AC electroosmotic effects. The study described in the paper can be used for placing and assembling micro and nano-electronic devices and objects at specific sites on various substrates, in combination with bio-inspired biological binding techniques such as DNA hybridization, antigen-antibody interactions, and ligand-receptor (avidin-biotin) interactions.
Covalently-linked Adducts of Single-walled Nanotubes with Biomolecules: Synthesis, Hybridization, and Biologically-Directed Surface Assembly
Authors: Baker Sarah E. , Lasseter Tami L. , Smith Lloyd M. , Hamers Robert J. 
Published: April 2011

ABSTRACTCovalently-linked adducts of single-walled carbon nanotubes (SWNTs) with biomolecules have been fabricated. Results are presented here for DNA-SWNT and for biotin-SWNT adducts. DNA-SWNT adducts are shown to be biochemically accessible and to exhibit high selectivity, favoring hybridization with complementary vs. non-complementary DNA sequences. Biotin-SWNT adducts were also prepared and used to direct the assembly of nanotubes onto a biotinylated glass surface.
Semi-Empirical Study of a pH-Switchable [2] Rotaxane
Authors: Frankfort Laura , Sohlberg Karl 
Published: April 2011

AbstractSemi-empirical (AM1) electronic structure calculations are reported on a pH-switchable [2] rotaxane whose synthesis was reported in [Angew. Chem. Int. Ed, 36 (1997) 1904] . The [2] rotaxane possesses two cationic binding sites, with different affinities toward dibenzo [24] crown-8 (the ring component of the [2] rotaxane) depending upon the pH of the system. The computational results capture this pH-sensitive bistability, the key device-like characteristic of the rotaxane.
Design and Performance of Polymeric Ultra-thin Substrates for use as Embedded Capacitors: Comparison of Unfilled and Filled Systems with Ferroelectric Particles
Authors: Andresakis John , Yamamoto Takuya , Pramanik Pranabes , Buinno Nick 
Published: April 2011

As CPUs increase in performance, the numbers of passive components on the surface of the boards are increasing dramatically. To reduce the number of components, as well as improve the electrical performance (i.e. reduce inductance), designers are increasingly embedding capacitive layers in the Printed Circuit Board (PCB).The majority of the products in use today utilize reinforced epoxy laminates. These products are relatively easy to handle and provide good electrical performance, but a need exists for even better performance than a fiberglass-reinforced product can produce.Other materials are being developed that are thinner (and thus increase capacitance and reduce inductance), but either have problems with dielectric breakdown strength, handling or only marginal improvements over the reinforced epoxy material. A need exists for an ultra-thin (less than 25 micron) material that not only provides improved electrical performance, but can be readily manufactured using standard PCB processing.We will discuss the design criteria we used for developing our family of products, as well as the results. The design of the conductor (copper foil) has been determined to be as critical as the properties of the dielectric (polymer). Examination of the effect of loading the polymer with High Dk ferroelectric particles will also be examined.The products have been through both internal and external testing and are compared to existing and developing capacitor materials. We will describe the electrical as well as the processing characteristics in detail, and how these types of products can greatly improve performance of high-speed systems
Solidly Mounted Bulk Acoustic Wave Filters
Authors: Loebl H. P. , Metzmacher C. , Milsom R. F. , Tuinhout A. , Lok P. , van Straten F. 
Published: April 2011

ABSTRACTSelective RF filters based on solidly mounted thin film bulk acoustic wave resonator filters (SMR filters) are of great interest for mobile and wireless applications in the GHz frequency range. They are small in size, robust and can be integrated on silicon. The SMR configuration comprises a textured piezoelectric layer of AlN or ZnO sandwiched between two electrodes, and an acoustic reflector, which confines the acoustic energy in the resonator region. The bulk acoustic wave (BAW) resonators are exited in the thickness extensional mode. In these paper examples of BAW resonators and filters for the frequency range between 1 and 8 GHz are shown. It will become clear that precise control of AlN film growth is very important. Modelling the resonator performance using a 1-dimensional electro acoustical model allows the extraction of important thin film parameters and thus simulation of the filter performance. Limitations of the 1-D model are discussed.
Investigation of Highly c-axis Oriented AlN Thin Film Re-growth
Authors: Martin F. , Muralt P. , Dubois M.-A. 
Published: April 2011

ABSTRACTThe properties of AlN films grown on a first set of differently treated AlN films have been studied by XRD, XPS, AFM, in-plane stress and interferometry. All films were deposited by dc pulsed sputtering at 300°C. The first set of films consisted of smooth, pure c-axis oriented AlN monolayers with narrow rocking curve width and excellent piezoelectric coefficient grown on platinized substrate in a large thickness range of 35–2000 nm. Subsequently, a 1000 nm AlN layer has been added. The use of a strongly alkaline developer during intermediate lithography steps and the time elapsed between the two steps of AlN re-growth were found to degrade the overall quality of the films. It's been shown that the alkaline developer etches down, increases the roughness and contaminates the surface of the AlN monolayer with mainly oxides and hydroxides while the exposure of the films to air develops a native oxide layer. By reducing the air exposure time and by the use of RF plasma cleaning prior to the re-growth process, a good piezoelectric coefficient can be recovered.
Surface Oxide Evolution on Al-Si Bond Wires
Authors: Qin Wentao , Doyle Ray , Scharr Tom , Shah Mahesh , Kottke Mike , Werho Dennis , Theodore N. David 
Published: April 2011

ABSTRACTAl-Si wires are often used to make contact to bond-pads of semiconductor chips and devices. During operation in certain types of devices the wires typically reach relatively high temperatures. Under such circumstances, the oxidation could lead to a decrease of wire conductivity. It is of interest therefore to understand the oxidation behavior of the bond wires, particularly at elevated temperatures. In the current study, Al-Si wires were characterized as received from the supplier, and after thermal annealing at 240°C and 300°C. The surface oxides were found to evolve from a single-layer oxide to a double-layer oxide with varying chemistry. Oxide thicknesses were substantially lower than the wire diameter, even after 3000 hours of annealing. Therefore oxidation of the Al-Si wires has an insignificant impact on their electrical conductivity.
Stress evolution in integrated SrBi2Ta2O9 ferroelectric layers
Authors: Lisoni J. G. , Wafer K. , Johnson J. A. , Goux L. , Schwitters M. , Paraschiv V. , Maes D. , Haspeslagh L. , Caputa C. , Zambrano R. , Wouters D. J. 
Published: April 2011

ABSTRACTIn our integration scheme, a “pseudo-3D” capacitor cell is used where the TiAlN\Ir\IrO2\Pt bottom electrode is patterned before SBT deposition. In order to understand how this system behaves mechanically, we have investigated the evolution of the stress of blanket Sr1-xBi2+yTa2O9 (x, y < 0.5) layers deposited on this pre-patterned bottom electrode stack. SBT was deposited by metal organic vapor deposition (MOCVD) between 405 °C and 440 °C. The stresses were monitored by the change in the radius of curvature of the wafer at the subsequent processing steps: deposition of electrodes and SBT, crystallization and recovering annealing, and after removal of Pt top electrode, SBT and bottom electrode layers by dry etching. The stress conditions observed for the different planar layers as a function of the SBT deposition temperature was correlated to the TiAlN lateral oxidation length observed in the etched structure after the SBT crystallization step.
Ferro- and piezoelectric properties of Bi4−xPrxTi3O12 polycrystalline thick films with Ps-vector orientation
Authors: Matsuda Hirofumi , Ito Sachiko , Iijima Takashi 
Published: April 2011

ABSTRACTTo reveal the complete performance of intrinsic ferroelectriciy-related properties in single crystalline bismuth-layer-structured displacive ferroelectrics in film form on Si, the crucial roles of both orientation control technology by lattice matching from the atomic arrangement of substrate layer and configuration of the volume fraction of 90°-domain during cooling process were demonstrated. 1.2 μm-thick and Pr3+-substituted Bi4-xPrxTi3O12 (BPT, x =0.0, 0.3, 0.5, 0.7) films were grown on Ir(111)/Ti/SiO2/Si(001) substrates by chemical solution deposition (CSD) method with preferred orientation along the major component of Ps vector. BPT film of x =0.3 exhibited superb ferroelectric properties of remanent polarization 2Pr=92 μC/cm2, saturation polarization Psat=50 μC/cm2, and coercive field 2Ec=184 kV/cm. The film also showed uniform piezoelectric response with an effective piezoelectric coefficient of AFM-d33=36 pm/V. During the decomposition of precursor solutions, IrO2 layers were formed at the surface of Ir layers and promoted a/b-axes orientation. During the cooling process after grain growth, in addition, the differential thermal expansion and residual strain between film and substrate introduced bidirectional lateral stress into BPT film and might eliminate the 90°-domain walls dividing a-and b-domains through the relaxation by domain formation at the Curie temperature TC. Consequently the polar-axis orientation was distinctively grown along the film normal and the conjugate non-polar-axis was grown in-plane.
Parametric Studies on Suppression of Secondary Phases in LiNbO3 Thin Films Deposited by Pulsed Laser Deposition
Authors: Son Ji-Won , Orlov Sergei S. , Phillips Bill , Hesselink Lambertus 
Published: April 2011

ABSTRACTWe performed a parametric study to suppress secondary phases in lithium niobate thin films by using pulsed laser deposition (PLD). A KrF excimer laser (λ=248nm) was used as a PLD source and c-oriented sapphire was used as substrates, for waveguide applications. By reducing the growth rate and changing the ambient gas pressure respectively, we found that the main parameter suppressing a secondary phase is controlling the plume strength. To investigate the relation between film phases and the plume strength, extensive parametric studies were performed by changing the oxygen ambient pressure, the target to substrate distance, and also the Li content in the target. The surface morphologies of single phase films and Li-deficient phase mixed films are compared and related to the growth mechanism with a lattice misfit. Deposition parameters to achieve lower loss films are also discussed.
Lead deficient PST Thin Films on LSCO/SrTiO3by RF-Sputtering
Authors: Martínez E. , Blanco O. , Fundora A. , Siqueiros J. M. 
Published: April 2011

ABSTRACTWe have investigated the structural, chemical and electrical properties of films with Pb0.6Sr0.4TiO3(PST60) nominal composition grown on well texturized LSCO/SrTiO3(STO) substrates by RF-Sputtering. The crystal structure and electrical properties of the PST60 films are remarkably influenced by the texture characteristics of the LSCO films. The structural and ferroelectric characteristics of PST60 thin films are determined to evaluate the potential of this heterostructure for non-volatile memory applications. Epitaxy of LSCO films was confirmed before depositing PST60 films on the above mentioned substrates through 4-Circle X-Ray Diffraction analysis (θ/2θ, ω and φ scans). The XRD analysis performed on the ferroelectric PST60 layer showed that the films are textured and entirely perovskite phase. LSCO and PST60, crystallize in the perovskite structure and their lattice parameters are well matched. This fact renders favorable structural and chemical conditions for the growth of PST60 on LSCO. The electrical performance of the Pt/PST60/LSCO/SrTiO3(001) capacitors was evaluated through Polarization-Voltage (P-V), Current-Voltage (I-V) and Fatigue measurements.
Ti-site Substitution Using the Higher-valent Cation for Enhancing the Ferroelectric Properties of Nd3+−substituted Bismuth Titanate Thin Films
Authors: Uchida Hiroshi , Koda Seiichiro , Matsuda Hirofumi , Iijima Takashi , Watanabe Takayuki , Funakubo Hiroshi 
Published: April 2011

ABSTRACTTi-site substitution using the higher-valent cation was performed on ferroelectric thin films of neodymium-substituted bismuth titanate, (Bi,Nd)4Ti3O12(BNT), in order to improve its ferroelectric properties by compensating the space charge in BIT-based crystal. Ti-site-substituted BNT films, (Bi3.50Nd0.50)1-(x/12)(Ti3.00-xVx)O15(x= 0 ∼ 0.09), were fabricated on (111)Pt/Ti/ SiO2/(100)Si substrates using a chemical solution deposition (CSD) technique. V5+-substitution enhanced the remanent polarization of BNT film without change in the coercive field. V5+-substitution also exhibited the possibilities for improving the endurance against leakage current and fatigue degradation.
Preparation, Microstructure and Physical Characteristics of Ferroelectric Pb5Ge3O11 Thin Films for Memory Application
Authors: Liu Y. X. , Caragianis-Broadbridge C. , Lehman A. H. , McGuinness J. , Ma T. P. 
Published: April 2011

ABSTRACTWe report sol-gel process of Pb5Ge3O11 (PGO) as well as the microstructure and physical properties of ferroelectric PGO films for memory applications. The PGO sol was prepared from lead acetate hydrate, germanium isopropoxide, and di(ethylene glycol) ethyl ether. The reactions taking place during the sol-gel process were examined in detail. Diethanolamine (DEA) was added to help maintain the desired species ratio and prevent germanium oxide precipitation. The preferred orientation of the PGO thin films was well controlled by the heating and reflux procedures in the sol-gel preparation process. Additionally, to examine the impact of postdeposition processing, selected samples were oxygen annealed at temperatures ranging from 450–650°C. The samples were characterized with X-ray diffraction (XRD), non-contact (planview) atomic force microscopy (NC-AFM). The resulting data indicate that the microstructure and physical properties of PGO films depend strongly on the precursor preparation as well as the post deposition annealing temperature.
Microstructure and ferroelectric behavior of nano-domains in ultra-thin BaTiO3 films
Authors: Drezner Y. , Berger S. 
Published: April 2011

AbstractMicrostructure studies of ultra-thin BaTiO3 thin films (2–10nm thick) show nano-domains having a width as small as one unit cell. Only 180° nano-domains and 90° domain-boundaries are formed in multi-domains structures. The domain-boundaries are formed at {111} twin boundaries. Most of the domains are oriented in parallel to the film plane but out-of-plane domains are also observed. The films exhibit ferroelectric behavior characterized by a polarization hysteresis loop. A remanent polarization of 3nC/cm2, coercive field of 0.7MV/cm were measured in vertical to the film plane. Temperature-dependent polarization measurements show two peaks of the dielectric constant at about 70°C and 110° C. These peaks are attributed to two Curie temperatures associated with the out-of plane and in-plane domain's orientation, respectively. The switching response of the nano-domains is relatively fast in the range of few nano seconds. The switching time decreases with increasing the applied electric field according to a power law dependence.
Property Improvement of Mocvd-Pzt Films Deposited Below 400 °C
Authors: Funakubo Hiroshi , Asano Gouji , Nagai Atsushi , Morioka Hitoshi , Yokoyama Shintaro , Shibutami Tetsuo , Oshima Noriaki , Akiyama Kensuke 
Published: April 2011

ABSTRACTRuO2/(200-nm thick PZT)/RuO2 capacitors were prepared by MOCVD. RuO2 and PZT films were prepared at 350, and 395 and 445 °C from DER - O2 and Pb(C11H19O2)2 - Zr(O·t-C4H9)4 - Ti(O·i -C3H7)4 - O2 systems, respectively. Clear hysteresis loops originated to ferroelectricity was observed for the PZT films deposited at 445 °C but was not at 395 °C. However, by the addition of 10-nm thick Pt layer prepared on the RuO2 bottom electrode by e-beam evaporation, ferroelectricity above 30 μC/cm2 in remanent polarization (Pr) was obtained for the PZT films deposited at 395 °C. This shows that the existence of Pt layer improved the crystallinity of PZT phase. This capacitor shows hardly fatigue up to 1 × 1010 switching cycles, suggesting the fatigue free characteristics.
Low Temperature Deposition of Ba0.96Ca0.04Ti0.84Zr0.16O3 Thin Films on Pt Electrodes by RF Magnetron Sputtering
Authors: Cramer N. , Philofsky Elliot , Kammerdiner Lee , Kalkur T. S. 
Published: April 2011

ABSTRACTBa0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) films acceptor-doped with 0.8 at. % Sc were deposited on Pt/TiO2/SiO2/Si substrates using rf magnetron sputtering. Substrate temperatures throughout the fabrication process remained at or below 450°C, which allows this process to be compatible with many materials commonly used in IC manufacturing. In addition, this process made no use of oxygen in the sputter gas or in annealing atmospheres and thus it remains compatible with easily oxidized materials. A relative dielectric constant of 166 was achieved along with a loss tangent of 0.006 to 0.17 at 10 kHz. The tunability of the dielectric constant was greater than 50 %. Leakage current densities of 1.6×10-8 A/cm2 were observed at 300K with 300 kV/cm of applied electric field. In comparison, Ba1-xSrxTiO3 (BST) films prepared under similar conditions show much greater leakage.
Conduction and Microwave Loss Mechanisms in Ba0.25Sr0.75TiO3 Films
Authors: Vorobiev Andrei , Rundqvist Par , Khamchane Khaled , Gevorgian Spartak 
Published: April 2011

ABSTRACTSilicon integrated parallel-plate Ba0.25Sr0.75TiO3 (BST) thin film varactors with Au bottom electrode have been prepared and characterized at dc and microwave frequencies. In the frequency range 0.045–45 GHz the varactors reveal extremely low loss tangent values (less than 0.025). However, this is still several times higher than loss in single crystal indicating occurrence of the extrinsic loss mechanisms. The analysis of BST film loss tangent and permittivity, depending on frequency and applied dc field, allow to attribute the dielectric loss to the charged defects. The dc current through varactor is found to be controlled by Poole-Frenkel mechanism associated with field enhanced thermal excitation of charge carriers from internal traps. It is assumed that charged defects and internal traps are the same type of BST film microstructure imperfection and possibly ascribed to be oxygen vacancies. The knowledge of the extrinsic loss mechanism and corresponding microstructure defects allows to optimize the deposition and/or anneal process and further improve the varactor performance.
Investigation of Retention Properties for YMnO3 Based Metal/Ferroelectric/Insulator/Semiconductor Capacitors
Authors: Yoshimura T. , Ito D. , Sakata H. , Shigemitsu N. , Haratake K. , Ashida A. , Fujimura N. 
Published: April 2011

ABSTRACTThe memory retention properties of Pt/YMnO3/Y2O3/Si capacitors were investigated for the application of ferroelectric gate transistors. The epitaxially grown Pt/YMnO3/Y2O3/Si capacitors showed ferroelectric type hysteresis loop on the capacitance-voltage properties. Although the retention time of the as-deposited capacitors was ∼103 s, it was prolonged up to 104 s when the leakage current density was reduced from 4×10-8 A/cm2 to 2×10-9 A/cm2 by the annealing under N2 ambience. To reveal the relationship between the retention time and leakage current, the leakage current mechanism was investigated comparing several conduction mechanisms. It was found that the dominant leakage mechanisms at high and low electric fields were Poole-Frenkel emission from the Y2O3 layer and ohmic conduction, respectively. This result indicates that the leakage current was limited by the Y2O3 layer at high electric field and was mainly dominated by the amount of defects in the YMnO3 layer at low electric field. From the pseudo isothermal capacitance transient spectroscopy (ICTS), it was determined that the trap density was in an order of 1015 cm-3. Since the variation of the leakage current by annealing was observed only in the low electric field region, it is suggested that the retention properties of the Pt/YMnO3/Y2O3/Si capacitors was influenced by the amount of defects in the YMnO3 layer.
Enhanced Piezoelectric Properties of Piezoelectric Single Crystals by Domain Engineering
Authors: Wada Satoshi , Yako Koichi , Kakemoto Hirofumi , Tsurumi Takaaki 
Published: April 2011

ABSTRACTFor tetragonal barium titanate (BaTiO3) single crystals, an electric field (E-field) applied along [111]c direction can induce an engineered domain configuration. In this study, the engineered domain structures with different domain sizes were induced into BaTiO3 single crystals, and their piezoelectric properties were investigated as a function of a domain size. Prior to this study, the dependence of domain configuration on the temperature and the E-field was investigated using a polarizing microscope in order to understand the optimum condition for fine and coarse domain structures. As a result, above Curie temperature (Tc) of 132.2 °C, when the E-field over 6 kV/cm was applied along [111]c direction, the engineered domain configuration with fine domain structure appeared. Moreover, it was also found that this fine domain structure was still stable at room temperature without E-field. On the other hand, the coarse domain structure was obtained by poling at just below Tc. Finally, the piezoelectric properties were measured using the 31 resonators with different kinds of domain sizes. As the result, it was found that the piezoelectric properties such as d31 and k31 increased significantly with decreasing domain sizes.