bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel High Power Piezoelectrics for Transformers and Actuators
Authors: Priya Shashank , Uchino Kenji 
Published: April 2011

ABSTRACTThis letter reports a Pb(Zr0.5Ti0.5)O3 (PZT) based composition, which provides high dielectric, piezoelectric and electromechanical properties. The composition corresponding to 0.2 PZN – 0.8 PZT + 0.5 wt% MnO2 provides the radial mode coupling factor (kp) of 0.58, longitudinal mode piezoelectric constant (d33) of 277 pC/N, dielectric constant (ε33/εo) of 946 and mechanical quality factor (Qm) of 1402. X-ray diffraction, dielectric and polarization-electric field measurements were done to investigate the origin for this high performance. It was found that high soft properties are obtained due to the shifting of PZT composition towards morphotropic phase boundary (MPB) and high hard properties are obtained due to the generation of dipolar defects which pin the polarization. The properties of the composition corresponding to 0.9 PZT – 0.1PMnN (Zr/Ti = 0.51/0.49) modified with 6 mol% Sr were found to be: kp = 0.53, Qm = 800, d33 = 274, ε33/εo = 1290 and tanδ = 1.1 %, with a TCF of -8 ppm/oC (-20 to 80°C). High piezoelectric properties with low TCF shows the suitability of this composition for ultrasonic devices used under fluctuating thermal environment.
Characteristics of Dopant Activation by Sequential Lateral Solidification (SLS)
Authors: Kim Yong-Hae , Sohn Choong-Yong , Chung Choong-Heui , Ko Young-Wook , Lee Jin Ho 
Published: April 2011

ABSTRACTThe characteristics of dopant activation by sequential lateral solidification in poly-Si films is investigated using sheet resistance measurement and Raman measurement. Sheet resistance of n+ and p+ doped poly-Si films decreases exponentially as the laser energy increases. The minimum sheet resistance of n+ doped poly-Si films is 150 Ω/□ which is near to that of rapid thermal annealing (RTA) while the minimum sheet resistance of p+ doped poly-Si films is 180 Ω/□ which is less than a half to that of RTA. The sheet resistance of n+ and p+ doped poly-Si increases as the laser energy increases when the laser energy is above 573 mJ/cm2 at which the nucleation occurs. Raman signal of n+ doped poly-Si films shows single peak at 515 cm-1 with all laser energy and has maximum intensity at 566 mJ/cm2 laser energy. Raman signal of p+ doped poly-Si films shows single peak below 413 mJ/cm2 laser energy and double peak above 444 mJ/cm2 laser energy where the fully melting of p+ doped poly-Si film occurs.
Star-like Aromatic Conjugated Polymers and Dendrimers for OLEDs
Authors: Khotina Irina A. , Baranova Diana Yu. , Burenkova Natalia S. , Gurskaja Anastasia A. , Valetsky Peter M. , Bronstein Lyudmila M. 
Published: April 2011

ABSTRACTHighly branched photoluminescent polyphenylenes (PP) containing 1,3,5-triphenylbenzene (TPB) fragments were prepared via combination of cyclocondensation of acetylaromatic compounds and Ni0-catalyzed dehalogenation. Defect free PP with star-like fragments were synthesized using Ni0-catalyzed polymerization of aromatic bromides obtained by modification of 1,3,5-tri(p-bromophenyl)benzene. The molecular weights of the polymers were 6700, 8600, and 15300 Da. The maximum photoluminescence in solution (quantum yield of 96%) was obtained for the highly branched polymer with star-like TPB fragments, bearing no Br or acetyl groups. The PP of this kind show also very bright fluorescence in a solid state under UV irradiation at 360 nm so they can be considered as promising materials for OLED applications.
Bioinspired approach of the composite materials: towards the active health monitoring concept
Authors: Gobin P. F. , Salvia M. , Monnier T. , Godin N. , Guy P. , Jayet Y. 
Published: April 2011

ABSTRACTThe classical NDE techniques of periodical maintenance are just now evolving towards the continuous health monitoring of materials and structures. Taking account of the relation of this approach with the bioinspired notion of smart materials, it seems useful to extend this passive concept to a more active one, especially in the case of materials systems as composite materials. Effectively, if sensors and actuators are embedded in a composite structure before curing in order to monitor and improve the processing parameters, they are able, remaining in the structure, to assume the health monitoring and some optimization of the usage in the next stages of the life. Moreover, in slightly damaged systems, it becomes reasonable to use the results collected by the sensors for improvements of safety of materials and structures. Finally in the last stage of the life, when the material is deeply damaged, it is sometimes possible to slow down, and more rarely, to heal the damage.
Tailoring strains through microstructural design
Authors: Vandeperre L.J. , Clegg W.J. 
Published: April 2011

ABSTRACTComposite structures are presented that allow a wide design space for strains in response to an applied stimulus to be accessed. The basic principle of operation is described and examples of how it can be used to obtain a range of behaviours are given. Experiments were conducted to assess the basic behaviour of building blocks for such composites and it is shown that the results agree reasonable with simple predictions made by considering bending and stretching of the beams in the structures.
Magnetization Process Associated with Rearrangement of Martensite Variants in Iron-Based Ferromagnetic Shape Memory Alloys
Authors: Fukuda Takashi , Sakamoto Tatsuaki , Terai Tomoyuki , Kakeshita Tomoyuki , Kishio Kohji 
Published: April 2011

ABSTRACTMagnetization processes of Fe-31.2Pd(at.%) and Fe3Pt (S ≈ 0.8) single crystals in martensite state have been examined in order to confirm the propriety of the condition for the rearrangement of variants under magnetic field: τmag>τreq, where τmag is the magnetic shear stress and τreq is the shear stress required for the rearrangement. When the magnetic field is applied along the [001] direction of each specimen, the magnetization curve shows a large hysteresis due to the rearrangement of variants. Its area, i.e., energy dissipation, is nearly the same as that obtained by stress-strain curves, suggesting the path of the rearrangement of variants by magnetic field is essentially the same as that by external stress. From the magnetization curve, the uniaxial magnetocrystalline anisotropy constant Ku is estimated: it is about 350 kJ/m3 for Fe-31.2Pd at 77 K, and is about 500 kJ/m3 for Fe3Pt at 4.2 K. The maximum of τmag, being evaluated from Ku and twinning shear, is about 2.8 MPa for Fe-31.2Pd at 77K and is about 4.3 MPa for Fe3Pt at 4.2K. For Fe-31.2Pd, the value of τreq is obtained by tensile tests at 80 K to be 0.5–2.5MPa, and the above condition is satisfied. The above condition is also confirmed to be adequate by examining the influence of field direction on the magnetic filed-induced strain.
Metal-containing diamond-like carbon-silicon nanocomposite films as temperature sensors
Authors: Takeno T. , Takagi T. , Bozhko A. , Shupegin M. , Sato T. 
Published: April 2011

ABSTRACTMetal-carbon nanocomposites are characterized by a number of unique properties, perspective for the various-type applications. The presented experimental data on the conductivity of amorphous tungsten- and niobium-containing carbon-silicon nanocomposite films show the possibility of the design of advanced wide-range temperature sensors, which are expected to possess the chemical stability, biocompatibility, mechanical, and other properties typical for this class of materials. The films were deposited onto polycrystalline substrates using combination of PECVD(Plasma Enhanced Chemical Vapor Deposition) of siloxane vapors and magnetron co-sputtering of metal target. The conductivity σ of the films, measured using standard 4-probe technique in the temperature range 80–400K, is characterized by the gradual decrease with temperature. The experimental σ(T) dependences are well fitted by the universal power expression, σ(T)= σ0+aTn, where σ0, a, and n are the fitting parameters dependent on the value of metal concentration. The conductivity mechanisms in the investigated amorphous metal-containing carbon-silicon nanocomposite films are discussed in the framework of the model of inelastic tunneling in amorphous insulators in the presence of the structural transformation in carbon-silicon matrix.
Organically Hybridized SnO2 Sensors for Selective Detection of Gas Molecules
Authors: Matsubara Ichiro , Hosono Kouta , Murayama Norimitsu , Shin Woosuck , Izu Noriya 
Published: April 2011

ABSTRACTGas sensors based on organically hybridized SnO2 films are demonstrated. Upon exposure to CO gas, the electrical resistance of the hybrid sensor with amino groups in the organic components increases (R-increasing response), whereas other reducing gases such as H2 and CH4 gases cause the decreasing in the sensor resistance. For the n-type semiconductors like SnO2, the R-increasing response cannot be explained by the ordinary combustion mechanism. The appearance of the anomalous R-increasing response to CO gas can be controlled by the functional groups of the organic component. The hybrid sensor with hydroxy groups also exhibits the R-increasing response to CO gas, whereas it is not observed for the sensor with alkyl groups. The hybridization can improve gas selectivity of the SnO2 semiconducting gas sensors.
Piezoelectric Transformers for Space Applications
Authors: Carazo Alfredo Vázquez 
Published: April 2011

ABSTRACTThere is a considerable excitement in the space community about the possibility of performing useful missions in space using vehicles that are much smaller in size than current spacecrafts. Lower cost and new type of missions made of this small satellite very attractive for future missions. Spacecraft in the mass range of 1 to 10 kilograms are often referred to as “nanosatellites”. However, the suite of useful missions for nanosatellite is limited by the dearth of space components of suitable scale. Present day nanosatellites are often drifting, uncontrolled packages of instrumentation of very limited capability. The vital subsystem functions of propulsion, power conversion and storage, attitude control, attitude sensing, data storage, command and data handling, and telemetry, tracking and control, are not well supported by these components availability of a number of small, low-cost nanosatellite components in these subsystem areas. This paper introduces the advances on applications based on piezoelectric transformers for nanosatellites.
Influence of Nitrogen Bonds on electrical properties of HfAlOx(N) films fabricated through LL-D&A process using NH3
Authors: Iwamaoto Kunihiko , Nishimura Tomoaki , Tominaga Koji , Yasuda Tetsuji , Kimoto Koji , Nabatame Toshihide , Toriumi Akira 
Published: April 2011

ABSTRACTWe have investigated the influence of nitrogen incorporation into the HfAlOx film prepared by LL-D&A process with NH3 annealing step on structural change and electrical properties. Also, we have evaluated the effects of PDA treatment on electrical properties. Nitrogen concentration in HfAlOx(N) film was enhanced with increasing the NH3 annealing temperature. The shift of Hf 4f average binding energy towards lower side was observed in proportion to nitrogen concentration in HfAlOx(N) film. This result indicates the partial change of the local coordination from O-Hf-O to O-Hf-N. The increase of O-Hf-N component drastically degraded the gate leakage current in HfAlOx(N) film. Nitrogen atoms still maintained in HfAlOx(N) film even after PDA at 850°C in O2 ambient. PDA treatment at higher temperature after D&A(NH3) process improved the flat-band voltage shift and the electron mobility.
Nitrided Hafnium Silicate Film Formation by Sequential Process Using a Hot Wall Batch System and Its Application to MOS Transistor
Authors: Aoyama Tomonori , Torii Kazuyoshi , Mitsuhashi Riichirou , Maeda Takeshi , Kamiyama Satoshi , Horiuchi Atsushi , Kitajima Hiroshi , Arikado Tsunetoshi 
Published: April 2011

ABSTRACTHigh quality HfSiON/SiO2 gate dielectrics were successfully formed using a hot wall batch system, which is suitable for mass production. The carbon contamination at HfSiON/SiO2 interface was reduced by a sequential process of the interfacial layer (IL) formation and HfSiOx metal organic chemical vapor deposition (MOCVD). The O3 treatment was found effective to reduce the residual carbon and hydrogen, while the NH3 treatment made the HfSiOx to be HfSiON, which was effective to prevent the phase separation and crystallization during the activation annealing. The NH3 treatment temperature above 700°C is necessary to suppress the boron penetration during the activation annealing at 1050°C for 1 sec in p-channel field effect transistor (p-FET). Equivalent oxide thickness (EOT) of 1.37 nm was achieved for HfSiON· (3nm)/SiO2(0.5nm) gate stack using poly-Si electrode. High effective mobility of 271/62 cm2/Vs (n/p at 0.8 MV/cm) was obtained.
AlON thin films formed by ECR plasma oxidation for high-k gate insulator application
Authors: Yamanaka Go , Uchikawa Takafumi , Ohmi Shun-ichiro , Sakai Tetsushi 
Published: April 2011

ABSTRACTAlON thin films formed by the electron cyclotron resonance (ECR) plasma oxidation of the AlN thin films deposited on p/p+−Si(100) by the ECR sputtering method were investigated for high-k gate insulator application. The leakage current density was found to be decreased with the ECR plasma oxidation of the AlN thin films. Furthermore, the equivalent oxide thickness (EOT) of 1.5 nm with the leakage current density of 5.1×10−4 A/cm2 (@Vfb−1 V) was obtained after the 1000°C rapid thermal annealing (RTA) because of the high quality interfacial layer formation.
Structural and Electrical Properties of HfO2 Films Grown by Atomic Layer Deposition on Si, Ge, GaAs and GaN
Authors: Fanciulli Marco , Spiga Sabina , Scarel Giovanna , Tallarida Grazia , Wiemer Claudia , Seguini Gabriele 
Published: April 2011

ABSTRACTHfO2 thin films were grown by atomic layer deposition on Si, Ge, GaAs and GaN substrates, using Hf(OtBu)2 (mmp)2 and HfCl4. The results show that this combination of precursors promotes a conformal and smooth growth of HfO2 films on all substrates. As grown films in the thickness range of 10–20 nm have the same electronic density and smooth surfaces. Films 20 nm thick are polycrystalline with the monoclinic structure, whereas the crystallized fraction in the 10 nm thick layers is much lower. The HfO2 /Ge interface is remarkably sharp. The dielectric constant of the HfO2 films is 15. Low density of interface states and oxide fixed charges are obtained for the films grown on Si. The optimization of the HfO2 interface with the other substrates requires more effort.
Growth of Perovskites with Crystalline Interfaces on Si(100)
Authors: Norga G. J. , Guiller A. , Marchiori C. , Locquet J. P. , Siegwart H. , Halley D. , Rossel C. , Caimi D. , Seo J. W. , Fompeyrine J. 
Published: April 2011

ABSTRACTThe main challenges involved in the growth of an epitaxial oxide film with a crystalline interface to silicon are reviewed: (1) structural matching of the oxide and semiconductor lattices; (2) thermodynamic energy stabilization at the semiconductor–oxide interface, and (3) kinetic control over oxygen motion throughout the deposition process. We report on how this approach can be used to grow epitaxial perovskites of high structural quality from the (Ba, Sr)(Zr,Ti)O3 family with crystalline interfaces on Si (100) by molecular-beam epitaxy.
Passivation of Oxide Layers on 4H-SiC Using Sequential Anneals in Nitric Oxide and Hydrogen
Authors: Williams J. R. , Isaacs-Smith T. , Wang S. , Ahyi C. , Lawless R. M. , Tin C.C. , Dhar S. , Franceschetti A. , Pantelides S.T. , Feldman L.C. , Chung G. , Chisholm M. 
Published: April 2011

ABSTRACTThe interface passivation process based on post-oxidation, high temperature anneals in nitric oxide (NO) is well established for SiO2 on (0001) 4H-SiC. The NO process results in an order of magnitude or more reduction in the interface state density near the 4H conduction band edge. However, trap densities are still high compared to those measured for Si / SiO2 passivated with post-oxidation anneals in hydrogen. Herein, we report the results of studies for 4H-SiC / SiO2 undertaken to determine the effects of additional passivation anneals in hydrogen when these anneals are carried out following a standard NO anneal. After NO passivation and Pt deposition to form gate contacts, post-metallization anneals in hydrogen further reduced the trap density from approximately 1.5 × 1012 cm−2eV−1 to about 6 × 1011 cm−2eV−1 at a trap energy of 0.1 eV below the band edge for dry thermal oxides on both (0001) and (11–20) 4H-SiC.
The Oxide/Nitride Interface: a study for gate dielectrics and field passivation
Authors: Gila B.P. , Luo B. , Kim J. , Mehandru R. , LaRoche J.R. , Onstine A.H. , Lambers E. , Siebein K. , Abernathy C.R. , Ren F. , Pearton S.J. 
Published: April 2011

ABSTRACTThe study of the effects of substrate surface preparation of GaN, both in-situ and ex-situ and the subsequent deposition of dielectric materials is necessary to create a viable GaN FET technology. Surface preparation techniques have been explored using RHEED, AES, SIMS and C-V measurements to produce films of low interface trap density, 1–2E11 eV−1cm−2. A similar study of the as-fabricated HEMT surface was carried out to create a cleaning procedure prior to dielectric passivation. Dielectric films of Sc2O3 and MgO were deposited via gas-source MBE. Post-deposition materials characterization included AES, TEM, XRR and XPS, as well as gate pulse and isolation current measurements for the passivated HEMT devices. From this study, the relationship between the interface structure and chemistry and the quality of the oxide/nitride electrical interface has been determined. The resulting process has led to the near elimination of the current collapse phenomenon. In addition, the resulting oxide/nitride interface quality has allowed for the first demonstration of inversion in GaN.
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.
The Synthesis and Catalytic Application of a New Class of Imprinted Silica
Authors: Bass John D. , Anderson Sandra L. , Katz Alexander 
Published: April 2011

AbstractThe effect of chemical environment surrounding a synthetic heterogeneous catalyst active site is investigated using the hydrophilic imprinting of silica. Two model reaction systems have been used for this study: (i) Knoevenagel condensation of 3-nitrobenzaldehyde and malononitrile and (ii) Suzuki coupling of bromobenzene and phenylboronic acid. Using a catalyst in which isolated imprinted amines are surrounded by an acidic silanol-rich environment led to rate accelerations of over 120-fold relative to catalysts in which the amines are surrounded by a hydrophobic environment consisting of trimethylsilyl functional groups for system (i). This result parallels our previous study on the effect of the outer sphere composition on rate acceleration of Knoevenagel reactions using isophthalaldehyde as the aldehyde reactant. We also extended our method for the hydrophilic imprinting of bulk silica to organometallic systems, by successfully synthesizing a tethered palladium complex within the imprinted pocket. This material was used as an active catalyst for (ii). Our results show that a hydrophobic framework environment results in higher initial turnover frequencies than an acidic silanol-rich framework for the Suzuki coupling reaction of bromobenzene and phenylboronic acid, albeit with a lower overall effect than observed in the Knoevenagel system (i). Altogether, these results demonstrate the control of chemical reactivity via the rational design of the outer sphere using an imprinting approach.
Steady-State Fluorescence Anisotropy Studies of Molecularly Imprinted Polymer Sensors
Authors: Chen Yin-Chu , Wang Zheming , Yan Mingdi , Prahl Scott A. 
Published: April 2011

ABSTRACTMolecularly imprinted polymers (MIPs) are used as recognition elements in biochemical sensors. In a fluorescence-based MIP sensor system, it can be difficult to distinguish the analyte fluorescence from the fluorescence of the polymer itself. We studied steady-state fluorescence anisotropy of anthracene imprinted in a polymer (polyurethane) matrix. Vertically polarized excitation light was incident on MIP films coated on silicon wafers; vertically and horizontally polarized emission was measured. We compared the fluorescence anisotropy of MIPs with imprinted molecules, MIPs with the imprinted molecules extracted, MIPs with rebound molecules, and non-imprinted control polymers. It is shown that differences in fluorescence anisotropy between the polymers and imprinted fluorescent molecules may provide a means to discriminate the fluorescence of analyte from that of the background polymer.
Molecular Imprinting of 3-Hydroxybenzoic Acid: Special and General Binding Sites
Authors: Hu Yue , Orwoll Robert A. 
Published: April 2011

ABSTRACTA resin, imprinted with 3-hydroxybenzoic acid (3HBA), was synthesized from acrylamide (AA, the functional monomer) and ethylene glycol dimethacrylate (EGDMA, the crosslinking agent). Batch analyses showed that the imprinted polymer has a special affinity for the meta-substituted 3HBA, but not for its para-substituted isomer (4HBA) nor for benzoic acid (BA). These results are consistent with the principle that an imprinted resin's ability to recognize is dependent on the target's size, shape, and functionality. Another resin, prepared from AA and EGDMA but in the absence of a template, had similar affinities for 3HBA, 4HBA, and BA; and thus it could not differentiate among the three. The results can be interpreted with a simple two-binding-site model with one site special for 3HBA and the other being more general with similar affinities for 3HBA, 4HBA and BA. The binding of 3HBA to the imprinted resin is characterized by an association constant and the density of each kind of site using a two-site Scatchard equation. The binding sites common to both the imprinted resin and the non-imprinted reference resin were found to have greater affinity but are less numerous than the sites unique to the imprinted resin.