bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis and Modeling of Electro-Mechanical Coupling in an Electroactive Polymer-Based Actuator
Authors: Bowers Thomas A. , Anquetil Patrick , Hunter Ian , Hogan Neville 
Published: April 2011

ABSTRACTA non-linear constitutive model was formulated for ionic electroactive polymers (EAP) to describe the energetic coupling between electrical and mechanical domains. The polymer was modeled as a multi-port energy storage element with inputs from the electrical and mechanical domain. Using energy conservation methods, general relationships between stress, strain, voltage, and charge were determined. A solution to the uniaxial loading boundary condition was developed fully and compared to a linear model published by Madden and an electrochemical model published by Mazzoldi et al. Experimental results from a conducting polymer actuator composed of polypyrrole were used to validate the electro-mechanical coupling model. It was found that the correlation between the model and experimental data was very good for strains up to 3% and applied voltages up to 1 Volt; these are within the typical operating range of polypyrrole. The model is sufficiently simply to allow real-time control while also exceeding the linear coupling models in its ability to predict polymer behavior in normal operating ranges.
Structural and dielectric proper ties of CaCu3Ti4O12 thin film. deposited using laser ablation.
Authors: Gupta V. , Das R.R. , Dixit A. , Bhattacharya P. , Katiyar R.S. 
Published: April 2011

ABSTRACTCaCu3Ti4O12 (CCT) thin films were deposited on Pt/TiO2/SiO2/Si substrates using pulsed laser deposition technique. During the thin films deposition, the substrate temperature was varied in the range of 700–800 °C with a constant O2 pressure of 200 mTorr. X-ray diffraction showed the polycrystalline nature of the films. The dielectric properties of the films were studied in metal insulator configuration. Films grown at higher substrate temperature exhibited highest value of dielectric permittivity (∼2200). Micro Raman spectroscopy was used to study the vibrational modes of the CCT thin films in comparison with the bulk ceramics.
Fabrication and Characterization of Fe-Pd Ferromagnetic Shape-Memory Thin Films
Authors: Sugimura Yuki , Cohen-Karni Tzahi , McCluskey Patrick , Vlassak Joost 
Published: April 2011

ABSTRACTFe-Pd thin films with approximately 30 at.% Pd have been produced by magnetron sputtering. Various heat treatment conditions were studied in order to obtain the face-centered tetragonal (fct) martensitic phase at room temperature. X-ray diffractometry was used to identify the various phases present at room temperature and the substrate curvature technique was employed to measure film stress as a function of temperature. The shape memory effect was demonstrated in samples containing the fct martensite phase at room temperature.
Characterization of the Electronic Structure and Optical Properties of Al2O3, ZrO2 and SrTiO3 from Analysis of Reflection Electron Energy Loss Spectroscopy in the Valence Region
Authors: Tan G. L. , Denoyer L. K. , French R. H. , Ramos A. , Gautier-Soyer M. , Chiang Y. M. 
Published: April 2011

ABSTRACTCharacterization of thin surficial films of oxides has become the focus of increased interest due to their applications in microelectronics. The ability to experimentally determine the electronic structure and optical properties of oxide materials permits the direct study of the interband transitions from the valence to the conduction band states. In the past years there has been much progress in the quantitative analysis of transmission electron energy loss spectroscopy (TEELS) in the electron microscopeHere we employed reflection electron energy loss function (REELS) as well as vacuum ultraviolet (VUV) spectroscopy to determine the dielectric functions of oxide materials, i.e. Al2O3, ZrO2 and SrTiO3. The two main steps in the analysis are the removal of the effects of multiple scattering from the REELS spectra followed by application of the Kramers-Kronig dispersion transforms to the single scattering energy loss function to determine the conjugate optical variable and then the complex dielectric function. The surface and bulk plasma resonance spectra for these oxide materials have been determined from VUV and REELS, along with the influence of primary electron energy on the REELS results. The relative contribution of surface and bulk plasmon oscillation in REELS has been investigated. Comparison with VUV results and existing TEELS results indicate that Kramers-Kronig analysis can also be applied to REELS spectra and the corresponding conjugate optical properties can be obtained. Quantitative studies of the electronic structure and optical properties of thin surficial films using VUV and REELS or TEELS, represent a new avenue to determine the properties of these increasingly important films.
Thermally Grown and Reoxidized Nitrides as Alternative Gate Dielectrics
Authors: Ludsteck Alexandra , Dietl Waltraud , Chung Hinyiu , Schulze Joerg , Nenyei Zsolt , Eisele Ignaz 
Published: April 2011

ABSTRACTThe use of high-k materials as gate dielectric still meets a lot of unsolved problems such as thermal instability during post deposition anneals resulting in the formation of interfacial oxide layers or bad process compatibility. As long as these requirements are not accomplished alternative gate dielectrics have to be formed by oxynitrides or gate stacks built of oxynitrides and some high-k material. In order to achieve a low equivalent oxide thickness (EOT) it is necessary to grow homogeneously thin oxynitrides which are nitrogen-rich and which have a high interface quality. Therefore we have studied the growth of thin nitrides and oxynitrides (EOT = 1 – 2nm) formed by rapid thermal nitridation in NH3 and wet reoxidation. By varying the partial pressure of NH3 in the process gas ambient NH3/Ar the nitride quality could be optimized: it was found that an optimized ratio of NH3 and Ar during nitridation improves the electrical properties of the nitrides and oxynitrides significantly. Interface state densities as low as those of dry thermal oxides and leakage current densities reduced by four orders of magnitude compared to SiO2 of the same EOT have been obtained. Due to the high incorporation of nitrogen into the oxynitride by rapid thermal nitridation and following oxidation the leakage current densities are also lower than those of most oxynitrides reported in literature. In addition we present data concerning the suppression of boron diffusion from p+ poly-Si electrodes. In summary the developed oxynitrides are suitable to bridge the gap between common SiO2 and new alternative gate dielectrics or to form gate stacks in combination with high-k materials.
High-k ZrO2 Gate Dielectric on Strained-Si
Authors: Bhattacharya S. , Samanta S. K. , Chatterjee S. , McCarthy John , Armstrong B. M. , Gamble H. S. , Maiti C. K. , Perova T. , Moore A. 
Published: April 2011

ABSTRACTThe growth and structural characterization of UHV-compatible LPCVD grown strained-Si layer on linearly graded relaxed SiGe layer and the electrical properties of the high-k ultrathin ZrO2 films deposited on strained-Si layer using microwave-plasma CVD at low temperature (150°C) are reported. The strained-Si layer has been characterized using AFM, TEM and Raman spectroscopy. The C-V and G-V characteristics of ZrO2 films have been used to calculate the interface trap density, Dit, near the midgap energy, and the fixed oxide charge density, Qf/q. These are found to be 2.24 × 1012 cm−2 eV−1 and 1.45 × 1011 cm−2, respectively. Poole-Frenkel (PF) conduction mechanism is found to dominate the current conduction at room temperature.
Ab-initio study on the γ-Al2O3 surfaces and interfaces.
Authors: Pinto Henry P. , Elliott Simon D. 
Published: April 2011

ABSTRACTThe controlled growth of alumina films by atomic layer deposition (ALD) is of great interest to the electronics industry, as high-k dielectrics are being sought for the next-generation of MOSFETS. We present a theoretical study of the alumina polymorph γ-Al2O3 based on density functional theory (DFT). The predicted bulk structure for γ-Al2O3 has the Al vacancy sites widely separated, which is in agreement with other theoretical predictions. We estimated the energy of several γ-Al2O3 surfaces namely: (111), (110) and (110). The atomic and electronic structure of the most stable (111) surface is discussed and compared with α-Al2O3 (0001). The adsorption and dissociation of the H2O onto the (111) surface is considered and H-diffusion is simulated. Finally, a model for the γ-Al2O3 (111)/aluminium-hydroxide interface is proposed and considered as an intermediate stage in the γ-alumina film growth mechanism.
p-type in ZnO:N by codoping with Cr
Authors: Kaminska E. , Piotrowska A. , Kossut J. , Butkute R. , Dobrowolski W. , Golaszewska K. , Barcz A. , Jakiela R. , Dynowska E. , Przezdziecka E. , Wawer D. 
Published: April 2011

ABSTRACTWe report on the fabrication of p-ZnO films by thermal oxidation of Zn3N2 deposited by reactive rf sputtering. With additional chromium doping we achieved p-type conductivity with the hole concentration ∼5×1017cm−3 and the mobility of 23.6 cm2/Vs at room temperature. We developed a method of surface passivation of p-ZnO that maintains its p-type conductivity over time-scale of months.
Improved structural properties of sputtered hafnium dioxide on silicon and silicon oxide for semiconductor and sensor applications
Authors: Grüger H. , Kunath Ch. , Kurth E. , Pufe W. , Sorge S. 
Published: April 2011

ABSTRACTHafnium dioxide HfO2 is a candidate with promising properties for semiconductor industries as well as for optical and sensorial applications under harsh environments. The material can be deposited using various techniques such as CVD or PVD in different thickness ranges. The chemical inertness of HfO2 and the high band gap draw the attention of this paper towards application in optics as active and protective layer at the same time, chemical and physical sensors, such as moisture sensors and thin film capacities. In order to improve the layer properties with the sensorial application in mind, the deposition process and the post-processing need to be tightly controlled.Layers with thicknesses between 100 and 150nm have been deposited by r.f. sputtering of a high purity HfO2 target onto bare or oxidized silicon wafers under Ar- or Ar/O2-athmospheres. Initially the HfO2 has a mainly amorphous structure. Subsequent annealing controls the growth of recrystallized areas characterized by grain size and ratio between crystals and amorphous bodies. High heating rates of about 50K/s and annealing temperatures ranging 800 to 1000°C in a rapid thermal annealing (RTA) chamber seem to be advantageous for the properties desired. The layer's structure such as grain size, crystal type and orientation was investigated using AFM, TEM and XRD. Layer tension was evaluated using laser deflection. The differences in structure found have been correlated to the chemical inertness obtained in measurements for layer applications.
Transparent Transistors Based on Semiconducting Oxides
Authors: Kwon Y.W. , Li Y. , Heo Y.W. , Jones M. , Vijay  , Jeong B.S. , Zhou J. , Li S. , Holloway P. , Norton D.P. 
Published: April 2011

ABSTRACTThe synthesis and properties of oxide-based thin film transistors (TFTs) is reported using pulsed laser deposition. The field effect transistors use ZnO as the channel material. Low leakage current density is achieved with amorphous (CeTb)MgAl11O19 (CTMA) serving as the gate oxide, whose dielectric strength is measured to be > 5MV/cm for structures fabricated on Indium Tin oxide (ITO) substrates. Capacitance-voltage properties show that n-type active layers are realized with undoped ZnO. Charge densities in undoped ZnO are measured to be 1018 to 1019 / cm3 using Hall measurement and CV plots. Current-voltage measurements for TFT operation are reported. Channel materials on patterned substrates show high conductance and modulation of channel conductance. C-V measurements with MOS structure using doped ZnO and ZnxMg1-xO will also be described. The properties of depletion mode TFTs fabricated with doped and undoped oxide channel will be discussed in detail.
Fabrication of SrRuO3 Epitaxial Thin Films on YBa2Cu3Ox / CeO2 / YSZ - Buffered Si Substrates by Pulsed Laser Deposition
Authors: Higuchi Takamitsu , Morozumi Koichi , Iwashita Setsuya , Ishida Masaya , Shimoda Tatsuya 
Published: April 2011

ABSTRACTPseudocubic SrRuO3 (100) epitaxial thin films were fabricated on Si (100) with a YBa2Cu3Ox / CeO2 / YSZ (yttria-stabilized-zirconia) triple buffer layer ∼ 14 nm thick by pulsed laser deposition (PLD). Reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) revealed that the first buffer layer of YSZ (100) was epitaxially grown on naturally oxidized Si (100) substrates with the process condition of PB (base pressure) = 1×10-Torr, PO2 (oxygen partial pressure) = 5×10- Torr, and Ts (substrate temperature) = 700 °C. Higher deposition rate of YSZ in the range of 0 ∼ 0.6 nm/min brought about better crystallinity with a smaller value of a full-width at half maximum (FWHM) in the YSZ (200) rocking curve. Subsequent deposition of CeO2, YBa2Cu3Ox, and SrRuO3 resulted in an SrRuO3 (100) epitaxial thin film exhibiting good crystallinity with FWHM = 1.7° in the SrRuO3 (200) rocking curve.
Elementary processes during the epitaxial growth of metal oxides: MgO/MgO(001).
Authors: Geneste Gregory , Morillo Joseph , Finocchi Fabio , Hayoun Marc 
Published: April 2011

ABSTRACTElementary processes governing the epitaxial growth of metal oxides, like adsorption and diffusion, have been studied theoretically in the prototypical case of MgO/MgO(001). Most of these processes need to be investigated in an ab initio approach since they are usually accompanied by strong modifications of the electronic structure. This study has been carried out within the density functional theory, and complemented by molecular dynamics simulations using a rigid-ion potential. The growth of the oxide passes through several oxido-reduction reactions at the surface. The adsorption and the diffusion of Mg and O are strongly different from each other, and change considerably at steps from flat terraces. All these results point out the need of realistic models for the growth of metal oxides that take into account the chemical behaviour of the involved species as well as the influence of the defects.
Electrical Characteristics of Metal - (La0.27Y0.73)2O3 - Silicon Capacitors
Authors: Preisler E. J. , Bojarczuk N. A. , Guha S. 
Published: April 2011

ABSTRACTAn investigation of metal-insulator-silicon capacitors, utilizing single crystal (La0.27Y0.73)2O3 as the insulator is presented. Crystalline insulators are of interest because of the possibilities of obtaining an atomically flat interface and entirely eliminating the presence of dangling bonds at the interface.Capacitance – voltage measurements performed on MIS capacitors demonstrate a dielectric constant of 11.4 and suggest the absence of any interfacial silicon oxide layer. The equivalent oxide thickness of the sample with the thinnest dielectric layer is 15 Å. The density of interface states for the best samples is found to be in the mid 1012 cm−2eV−1 range and did not vary significantly after typical annealing treatments.
Hetero-Epitaxy of Crystalline Perovskite Oxides on GaAs(001)
Authors: Liang Y. , Kulik J. , Wei Y. , Eschrich T. , Curless J. , Craigo B. , Smith S. 
Published: April 2011

ABSTRACTHetero-epitaxy of crystalline perovskite SrTiO3 and BaTiO3 on GaAs(001) was achieved using molecular beam epitaxy. A number of surface and interface techniques were used to characterize the growth, structural, and chemical properties of epitaxial oxide films on GaAs. Reflection-high-energy-electron diffraction of SrTiO3 and BaTiO3 showed streaky diffraction features and low diffraction background through out growth, indicating that the epitaxial SrTiO3 and BaTiO3 films had good crystallinity. X-ray diffraction showed an epitaxial relationship between these perovskite oxides and GaAs(001) substrates. Transmission electron microscopy and scanning probe microscopy revealed an abrupt oxide/GaAs interface and smooth SrTiO3 and BaTiO3 surfaces. The success of growth of epitaxial perovskite oxides on GaAs enabled us to integrate a number of functional oxides such as piezoelectric and magnetic oxides epitaxially on GaAs substrates.
Molecular Simulations of Recognitive Polymer Networks Prepared by Biomimetic Configurational Imprinting as Responsive Biomaterials
Authors: Henthorn David B. , Peppas Nicholas A. 
Published: April 2011

AbstractProteins, enzymes, and antibodies have the ability to discern specific molecules out of a whole host of species and selectively bind them with remarkable affinity. A route that would enable the creation of synthetic polymers with this binding ability would be a great advance with subsequent applications in chemical sensors, single-molecule separations, and even artificial enzymes. In this work we study the molecular imprinting process whereby a controlled nanostructure consisting of distinct binding sites is created in a polymer network through a templating procedure. Simulations were done to better understand the underlying network structure that gives rise to the increased uptake. An all-atom molecular dynamics simulation was coupled with a kinetic gelation approach to study network formation in the presence of a template. The monomers used were first studied with density-functional theory in order to parameterize a force field for various methacrylates. Simulation results showed three key functional group interactions that lead to successful imprinting and subsequent rebinding.
Isomeric glucose recognition using molecularly imprinted polymer hydrogels
Authors: Parmpi Paraskevi , Bolisay Linden D.V. , Kofinas Peter 
Published: April 2011

ABSTRACTThe goal of this research is to produce molecular imprinted polymers (MIPs), which selectively bind glucose over other sugars. MIP hydrogels against glucose exhibited binding capacities in excess of 0.6 grams of glucose per gram of dry gel in a 100 % DI H2O glucose solution, as well as in a 50–50 % glucose-fructose solution mixture. Equilibrium binding capacities of fructose were lower than those observed with respect to glucose, indicating an isomeric preference for the binding of glucose over fructose. Although it is expected that imprinted cavities will be distorted due to the swelling of the hydrogel in water, our experiments show that even the swollen gels exhibit remarkable glucose recognition. This synthetic and characterization methodology for MIPs might thus offer exciting avenues for novel biomimetic recognition and isomeric separation techniques.
Molecularly Imprinted Micro- and Nano-Particles by Precipitation Polymerization
Authors: Ye Lei 
Published: April 2011

ABSTRACTMolecularly imprinted micro- and nano-particles can be conveniently prepared using precipitation polymerization method. By controlling the initial reaction composition, the resulting polymer particles may be obtained as uniform beads that display favourable binding characteristics. Incorporation of a novel reporter element resulted in an imprinted scintillation polymer that displayed an enhanced signalling efficiency.
Preparation of Metal Oxide Nanowires by Hydrothermal Synthesis in Supercritical Water
Authors: Hakuta Yukiya , Hayashi Hiromichi , Arai Kunio 
Published: April 2011

ABSTRACTThree kinds of single metal oxide (MnO2, ZnO, and AlO(OH)) and one complex metal oxide (K2O·6TiO2) having nano structure of wire, rod and ribbon were rapidly synthesized by hydrothermal synthesis in supercritical water. Aqueous Mn(NO3)2, Zn(NO)2, Al(NO3)3 solutions and mixtures of TiO2 sols and KOH solutions were used as starting materials, respectively. Syntheses of these nanostructured materials were performed by a flow type apparatus. We investigated the relationship between reaction parameters (temperature, pH and reaction time) and morphologies of the products. Reaction temperatures were 350, 400, and 420 °C. Reaction time is in the range of 1.8 – 116 s. The product was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that particle morphologies strongly depend on pH for MnO2 and ZnO. MnO2 nanowires with 10 nm in diameter and ZnO nanorods with 50 nm in diameter were obtained from acidic metal salt solutions. In the case of AlO(OH), temperature and time were key parameters for crystal growth. In the case of K2O6TiO2, larger fibrous particles with 50 nm in diameter were obtained at higher reaction temperature.
ZnS nanoparticles synthesis and characterization
Authors: Axmann Yvonne , Petri Alke , Hofmann Heinrich 
Published: April 2011

ABSTRACTZnS:Mn2+ nanoparticles were synthesized via a wet chemical method with L-cysteine as the stabilizing agent. The obtained aqueous dispersions show an orange luminescence, which is typical for the 4T1 → 6A1 transition within the Mn2+ d-orbitals. The fluorescence quantum yield has been determined with quinine sulphate as a dye reference. It can be increased after formation of a SiO2 shell around the particles by a factor of three. The particle size was determined with transmission electron microscopy (TEM), X-ray diffraction and PCS measurements.
Photocurrent in a hybrid system of 1-thioglycerol and HgTe quantum dots
Authors: Kim Hyunsuk , Cho Kyoungah , Min Byungdon , Lee Jong Soo , Sung Man Young , Kim Sung Hyun , Kim Sangsig 
Published: April 2011

ABSTRACTPhotocurrent mechanism in a hybrid system of 1-thioglycerol and HgTe quantum dots(QDs) was studied for the first time in the intra-red (IR) range. 1-thioglycerol-capped HgTe QDs were prepared using colloidal method in aqueous solution; the synthesis and size of the HgTe QDs were examined by x-ray diffraction, Raman scattering, and high-resolution transmission electron microscopy. Absorption and photoluminescence spectra of the capped HgTe QDs revealed the strong excitonic peaks in the range from 900 to 1100nm, because of their widened band gap due to the shrinkage of their sizes to about 3 nm. The wavelength dependence of the photocurrent for the hybred system of the 1-thioglycerol and HgTe QDs was very close to that of the absorption spectrum, indicating that charge carriers photoexcited in the HgTe QDs give direct contribution to the photocurrent in the medium of 1-thioglycerol. In this hybrid system, the photo-excited electrons in the HgTe QDs are strongly confined, but the photo-excited holes act as free carriers. Hence, in the photocurrent mechanism of the this hybrid system, only holes among electron-hole pairs created by incident photons in the HgTe QDs are transferred to 1-thioglycerol surrounding HgTe QDs and contribute photocurrent flowing in the medium of 1-thioglycerol.
Monocrystalline InP Nanotubes
Authors: Bakkers Erik. P. A. M. , Feiner Louis F. , Verheijen Marcel. A. , van Dam Jorden A. , Franceschi Silvano De , Kouwenhoven Leo 
Published: April 2011

ABSTRACTIndium phosphide (InP) nanowires and nanotubes have been synthesized via the vapor-liquid-solid (VLS) growth mechanism. The wires as well as the tubes are crystalline and have the (bulk) zinc blende structure. Compared to the nanowires the nantubes are formed at higher temperatures. A simple model for the formation of the nanotubes is presented. The diameter of the wires and the wall thickness of the tubes can be controlled by the synthesis temperature. Photoluminescence measurements on individual wires show a strong polarization dependency. Moreover, the nanostructures exhibit a considerable blue shift with respect to bulk emission as a result of size-quantization. In addition, this blue shift indicates that the optical properties are not dominated by defect states.