bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Microstructures of Ferroelectric SrBi2Ta2O9, BaTiO3 and Metallic SrRuO3 Epitaxial Thin Films
Authors: Jiang Q. D. , Huang Z. J. , Chen C. L. , Brazdeikis A. , Jin P. , Feng H. H. , Benneker A. , Chu C. W. 
Published: April 2011

ABSTRACTWe have made a comparative invetigation of the surface microstructures of epitaxially grown ferroelectric SrBi2Ta2O9, BaTiO3 films, and metallic SrRuO3 films, using scanning probe microscopy. Though their lattices (or pseudotetrogonal lattices) match closely with SrTiO3 (001) substrates, SPM results show very different surface microstructures. The surfaces of SrRuO3 films display atomically flat terraces of 90° oriented step edges. The size of steps is about 6 Å. The surface of BaTiO3 films deposited at various temperatures displays uniform rectangular islands. Different stages of SrBi2Ta2O9 epitaxial growth have been studied on thickness gradient films, which show clearly 2D nucleation and layer-by-layer growth, following a transition from 2D to 3D island growth. It finally develops into a surface exhibiting round hills consisting of curved terraces with size of steps ranging from 6 Å to 12.5 Å.
Seeded Epitaxial Growth of PbTiO3 Thin Films on (001) LaAlO3 using the Chemical Solution Deposition Method
Authors: Kim J. H. , Lange F. F. 
Published: April 2011

ABSTRACTEpitaxial PbTiO3(PTO) thin films were grown on (001) LaAlO3 (LAO) substrates by a two-step process from a mixed Pb-Ti double-alkoxide solution precursor. Scanning electron microscopy, x-ray diffraction, atomic force microscopy, and transmission electron microscopy were performed to characterize the microstructure of films and to evaluate the epitaxial phenomena. In the first step, very thin PTO films were deposited and then heat treated at 800 °C for lh. The films were broken up into isolated islands that have epitaxial relationship of [100](001)PTO∥[100](001)LAO. In the second step, another PTO thin films were deposited and then annealed at temperatures between 380 °C and 800 °C for 1h. In this seeded process, epitaxial PTO thin films, unobtainable when PTO thin films were deposited on the unseeded LAO substrates, could be grown. The islands formed in the first step act as seeds for the growth of epitaxial thin film in the second step.
Piezoelectric Properties of Sol-Gel Derived PZT Thin Films with Various Zr/Ti Ratios
Authors: Teqwee G. , McCarthy K. C. , McCarthy F. S. , Davis D. G. , Dawley J. T. , Zelinski B.J.J. , Uhlmann D. R. 
Published: April 2011

ABSTRACTPiezoelectric thin films are useful for application in microelectromechanical devices. A series of sol-gel derived PZT (lead zirconate titanate) thin films with various Zr/Ti ratios were prepared on platinized substrates. These films were fired to 650C - 700C to crystallize them into single-phase perovskite films, and their piezoelectric properties were measured using optical lever-based instrumentation. Large d33 piezoelectric coefficients up to 400 pm/V were obtained at the morphotropic phase boundary (PZT 53/47), making such films attractive in applications such as thin film transducers, microcanti levers and surface acoustic wave devices.
Structure and Physical Properties of Bi4Ti3O12Thin Films Prepared by APMOCVD and RTA
Authors: Wang H. , Wang Z. , Shang S. X. , Wang M. 
Published: April 2011

ABSTRACTFerroelectric Bi4Ti3O12 thin films were grown by atmospheric pressure metal-organic chemical vapor deposition. After rapid thermal annealing (RTA), the films have a (001) preferred orientation, The I-V and C-V characteristics were studied, the resistivity were in the rang of 1010∼1013 ω. cm, at room temperature. The memory window is about 3V. These results snow that The Bi4Ti3O12 films prepared at present work are suitable for making ferroelectric FEFETs memories. By using planar silicon processing, the FEFET devices have been fabricated, which shows clearly memory effect under a applied ±5V gate voltage.
Novel Antimony Precursors for Low-Temperature CVD of Antimonide Thin Films
Authors: Todd Michael A. , Bhandari Gautam , Baum T. H. 
Published: April 2011

ABSTRACTVolatile antimony precursors were synthesized for the low temperature chemical vapor deposition (CVD) of antimony thin films. The molecules synthesized include tris (trifluoromethyl)stibine, Sb(CF3)3, Lewis base adducts of Sb(CF3)3, and antimony trihydride (stibine), SbH3. Isotopie substitution of stibine with deuterium leads to a more thermally stable, carbon-free antimony source. Similarly, deuterium substitution of trimethylsilylmethyl antimony dihydride leads to a stabilized liquid antimony precursor. The molecules were characterized using FTIR, NMR and DSC / TGA. Pure antimony films were deposited at temperatures below 300 °C with growth rates approaching 170 Å / min using a low pressure hot-wall CVD reactor. The films were characterized using XRD, EDS, SEM and AFM.
Investigation of Low Molecular Weight Carbosilanes as Potential Single-Source Precursors to Silicon Carbide
Authors: Lienhard M. A. , Interrante L. V. , Larkin D. J. 
Published: April 2011

ABSTRACTSeveral volatile, low molecular weight, linear and cyclic carbosilanes containing a 1:1 Si:C ratio were studied as single-source CVD precursors to SiC. A comparison of methylsilane, 1,3-disilacyclobutane, 1,3-disila-n-butane, and 1,3,5-trisilacyclohexane in terms of both their pyrolysis chemistry (decomposition onset temperatures and gaseous by-products) and resulting film characterization (growth rate, stoichiometry, crystallinity and morphology) is presented. Polycrystalline β-SiC films were deposited by LPCVD on Si (100) substrates at temperatures ranging from 800°C to 1100°C by using each of these single-source precursors.
Spray Chemical Vapor Deposition of CuInS2 Thin Films for Application in Solar Cell Devices
Authors: Hollingsworth Jennifer A. , Buhro William E. , Hepp Aloysius F. , Jenkins Philip P. , Stan Mark A. 
Published: April 2011

ABSTRACTChalcopyrite CuInS2 is a direct band gap semiconductor (1.5 eV) that has potential applications in photovoltaic thin film and photoelectrochemical devices. We have successfully employed spray chemical vapor deposition using the previously known, single-source, metalorganic precursor, (Ph3P)2CuIn(SEt)4, to deposit CuInS2 thin films. Stoichiometric, polycrystalline films were deposited onto fused silica over a range of temperatures (300–400 °C). Morphology was observed to vary with temperature: spheroidal features were obtained at lower temperatures and angular features at 400 °C. At even higher temperatures (500 °C), a Cu-deficient phase, CuIn5S8, was obtained as a single phase. The CuInS2 films were determined to have a direct band gap of ca. 1.4 eV.
Morphology and Electron Emission Properties of Nanocrystalline CVD Diamond Thin Films
Authors: Krauss Alan R. , Gruen Dieter M. , Zhou Daniel , Mccauley Thomas G. , Qin Lu Chang , Corrigan Timothy , Auciello Orlando , Chang R. P. H. 
Published: April 2011

ABSTRACTNanocrystalline diamond thin films have been produced by microwave plasma-enhanced chemical vapor deposition (MPECVD) using C60/Ar/H2 or CH4/Ar/H2 plasmas. Films grown with H2 concentration ≤ 20% are nanocrystalline, with atomically abrupt grain boundaries and without observable graphitic or amorphous carbon phases. The growth and morphology of these films are controlled via a high nucleation rate resulting from low hydrogen concentration in the plasma. Initial growth is in the form of diamond, which is the thermodynamic equilibrium phase for grains < 5 nm in diameter. Once formed, the diamond phase persists for grains up to at least 15–20 nm in diameter. The renucleation rate in the near-absence of atomic hydrogen is very high (∼1010 cm2sec−1), limiting the average grain size to a nearly constant value as the film thickness increases, although the average grain size increases as hydrogen is added to the plasma. For hydrogen concentrations less than ∼20%, the growth species is believed to be the carbon dimer, C2, rather than the CH3* growth species associated with diamond film growth at higher hydrogen concentrations. For very thin films grown from the C60 precursor, the threshold field (2 to ∼60 volts/micron) for cold cathode electron emission depends on the electrical conductivity and on the surface topography, which in turn depends on the hydrogen concentration in the plasma. A model of electron emission, based on quantum well effects at the grain boundaries is presented. This model predicts promotion of the electrons at the grain boundary to the conduction band of diamond for a grain boundary width ∼3–4 Å, a value within the range observed by TEM.
MOCVD of Field Emission Phosphors using a Liquid Delivery System
Authors: Moss T. S. , Espinoza B. F. , Salazar K. V. , Dye R. C. 
Published: April 2011

ABSTRACTThin film phosphors for field emission displays show the potential to overcome the life-limiting problems that traditional powders face because of their high surface areas. By depositing a fully dense thin film, the surface area can be dramatically reduced, while the electrical and thermal conductivity is increased. Metal organic chemical vapor deposition offers the ability to deposit high quality, dense films that are crystalline-as-deposited and at temperatures low enough to allow for inexpensive glass. Deposition has been produced from mixtures of Y(tmhd)3, TEOS, Tb(tmhd)3, and O2 using a liquid delivery system. Coatings were shown to be composed of Y, Si, and Tb by x-ray fluorescence, but x-ray diffraction did not show any crystallinity. Excitation using radioluminescence produced a peak in the visible green at approximately 540 nm, indicative of the excitation of Tb3+. The morphology of the deposition was smooth, with surface features on the order of one micron and below. Some limited microcracking was also observed in the morphology because of the thermal expansion mismatch.
Materials Chemistry and Bulk Crystal Growth of Group III Nitrides in Supercritical Ammonia
Authors: Kolis Joseph W. , Wilcenski Steven , Laudise Robert A. 
Published: April 2011

ABSTRACTReasonably sized crystals of aluminum and gallium nitrides can be grown in supercritical ammonia using chloride and amide as the mineralizer. Best growth was achieved at 380°C in ammonia at 40,000 psi (270 MPa). Under these conditions crystals as large as 0.4 mm could be grown over several days. Attempts to optimize the identity and concentration of the mineralizer, and the acidity of the solution, led to several new products including A1F3(NH3)2.
Surface Characterization of Calcium-Stabilized Zirconia Film by X-Ray Photoelectron Spectroscopy
Authors: Bensadon E. O. , Nascente P. A. P. , Bulhões L.O.S. , Pereira E. C. 
Published: April 2011

ABSTRACTA new methodology was developed to stabilized zirconia films at room temperature. The zirconium oxide films were prepared electrochemically by anodic oxidation of metallic zirconium at constant curcent density. X-ray diffraction (XRD) revealed the partial stabilization of the cubic phase in the ZrO2 films obtained in the presence of calcium. On the other hand, the films obtained in H3PO4 presented monoclinic phase. Scanning electron microscopy (SEM) showed that the oxide films obtained in calcium medium were porous, while the films obtained in H3PO4 were compact. X-ray photoelectron spectroscopy (XPS) identified ZrO2 and the intercalation of Na, N, P and CaO, as well as adventitious carbon. Using depth profiling, we observed that the concentrations of ZrO2, P and CaO increased with sputtering time.
Photochemical Pattern Etching of Single-Crystalline 3C-SiC
Authors: Mori T. , Hatao K. , Murahara M. 
Published: April 2011

ABSTRACTA single-crystalline 3C-SiC is very difficult to etch compared with a polycrystalline SiC. Thus, a photochemical pattern etching of the SiC was demonstrated by using Xe2* excimer lamp and ArF or KrF excimer laser. To promote the surface reaction, a Xe2* excimer lamp was employed to produce many radicals on the sample surface; simultaneously, ArF or KrF laser light irradiated the surface via a circuit pattern to dissociate the Si-C bonds. The Si and C reacted with the F and N radicals photo-dissociated from NF3 gas to form SiF4, CFn and CN, which diffused in the reaction cell. As a result, the single-crystalline 3C-SiC was photo-chemically etched effectively. With the NF3 gas of 200Torr, the Xe2* excimer lamp of 7mW/cm2, and the KrF excimer laser of 650mJ/cm2, 20Hz and 10,000shots, the etch depth of 700 Å was successfully achieved.
Low Temperature Chemical Vapor Deposition of Titanium Dioxide Thin Films Using Tetranitratotitanium (IV)
Authors: Gilmer D. C. , Gladfelter W. L. , Colombo D. G. , Taylor C. J. , Roberts J. , Campbell S. A. , Kim H.-S. , Wilk G. D. , Gribelyuk M. A. 
Published: April 2011

ABSTRACTCrystalline titanium dioxide films were deposited on silicon (100) at temperatures as low as 184°C using the volatile molecular precursor, tetranitratotitanium(IV). Deposition rates in a low pressure chemical vapor deposition (LPCVD) reactor operated at 230 – 500°C with a precursor vessel temperature at 22°C were typically 4 nm/min. The effect of deposition temperature and annealing conditions on morphology are shown. Following post-deposition annealing in oxygen and hydrogen, Pt/TiO2/Si/Al capacitors were fabricated and exhibited dielectric constants in the range of 19 – 30 and leakage current densities as low as 10−8 Amp/cm2.
Formation of Platinum and Palladium Bimetallic Superfine Particles by Ultrasonic Irradiation
Authors: Fujimoto Toshiyuki , Terauchi Shinya , Umehara Hiroyuki , Kojima Isao , Henderson William 
Published: April 2011

ABSTRACTPt/Pd bimetallic nanoparticles were prepared by ultrasonic irradiation of aqueous solutions containing salts of both metal ions. Uniform bimetallic particles were found to have a 2.8 nm average diameter and a narrow size distribution. The size was similar to Pt monometallic particles, and the shape was similar to Pd monometallic particles, both prepared by ultrasound in the same way.
The Impact of the Graphite Nanofiber Structure on the Behavior of Supported Nickel
Authors: Park C. , Baker R. T. K. 
Published: April 2011

ABSTRACTIn the current investigation we have used the hydrogenation of ethylene and crotonaldehyde as probe reactions in an attempt to follow any changes in catalytic behavior induced by supporting nickel on different types of graphite nanofiber support materials. The hydrogenation of the α,β-unsaturated aldehyde to the desired product, crotyl alcohol, is a particularly difficult task since there is a strong tendency to hydrogenate both the C=C and C=O in the reactant molecule. This study is designed to compare the catalytic behavior of the metal particles when dispersed on three types of nanofibers, where the orientation of the graphite platelets within the structures is significantly different in each case. The metal crystallites are located in such a manner that the majority of particles are in direct contact with graphite edge regions. For comparison purposes, the same set of hydrogenation reactions were carried out under similar conditions over γ-Al2O3 supported nickel particles.
The Hydrothermal Synthesis and Characterization of New Organically Templated Layered Vanadium Oxides by Methylamine
Authors: Chen Rongji , Zavalij Peter Y. , Stanley Whittingham M. 
Published: April 2011

ABSTRACTThe hydrothermal reaction of vanadium pentoxide with methylamine leads to a series of new layered vanadium oxides by using different acids to adjust the initial pH. The structure of these layered vanadium oxides was established by X-ray single crystal and powder diffraction. The new phases were also characterized by TGA and FTIR. The oxidation state of vanadium was determined. These materials are expected to exhibit catalytic activity and may be of interest as cathode materials for secondary lithium batteries.
Catalytic Decomposition of Perfluorocompounds
Authors: Kanno S. , Ikeda S. , Yamashita H. , Azuhata S. , Irie S. , Tamata S. 
Published: April 2011

ABSTRACTIt is becoming increasingly important to decompose PFCs (Perfluorocompounds), which are powerful greenhouse gases. The process of catalytic decomposition is expected to be effective in operating at lower temperatures if catalysts of high activity and durability are developed. The decomposition activities of PFC with H2O was investigated using several catalysts. It was found that PFC decomposition activity was related to the reactivity of fluorine and the formation of mixed oxides. Using the catalyst we have developed, CF4 was decomposed with conversion above 99.9% over 1988h. Furthermore, another PFC was decomposed over the catalyst. The order of the conversion was CHF3 > CF4 > C2F6. The catalytic decomposition system can use the treatment of PFCs in dry etch process waste gas.
Generating Structural Models of Amorphous Tetrahedral Carbon: Basis set Dependencies
Authors: Schultz Peter A. , Stechel E. B. 
Published: April 2011

ABSTRACTWe present the results of a systematic first-principles investigation of the requirements for developing realistic and reliable structural models for amorphous tetrahedral carbon (a-tC) and relate those structural models to the physical properties of this material. Within a linear combination of atomic orbitals formulation of density functional theory, we show that a large variational flexibility is required to accurately treat the highly defected and strained structures that can exist in a-tC. The average strain in the a-tC lattice is predicted to be roughly twice the strain of having all carbon atoms in three-member rings. A key figure of merit of a structural model, the proportion of three-fold bonded atoms, is shown to triple in going from a minimal basis description of a structure to a high quality basis. The basis-converged calculations agree well with experimental observables, such as the presence of four-member rings, lack of dangling bonds, and a significant gap. The simulations predict a much larger proportion of three-fold atoms than estimated in simple analyses of EELS and neutron scattering experiments. We show that the larger three-fold fraction is indeed consistent with the properties of a-tC, and imply that there are flaws in the simplifying assumptions that go into constructing experimental estimates of coordination numbers. These results highlight the perils of applying highly simplified theoretical models for a-tC before the correct physics has been identified and built into the models.
Hydrogenated Carbon-Nitrogen Films Obtained by Pecvd using Acetylene and Nitrogen as Precursor Gases
Authors: Jacobsohn L. G. , Franceschini D. F. , Freire F. L. 
Published: April 2011

ABSTRACTAmorphous hydrogenated carbon-nitrogen films were deposited by plasma enhanced chemical vapor deposition (PECVD) using acetylene-nitrogen mixtures. The atomic composition and density of the films were determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERDA). Raman and Infrared spectroscopies monitored their structure. The addition of nitrogen gas to the deposition atmosphere resulted in a decrease in the film deposition rate. The increase of the nitrogen content is accompanied by the reduction of the carbon content. The IR absorption spectra show an increase intensity of the C=N Raman band and the N-H and CsN stretching bands. On the other hand, the IR results show a decrease in the intensity of the C-H stretching band. Raman results suggest an increase with the nitrogen content of the fraction of carbon atoms in a sp2 state of hybridization with the nitrogen content. The internal compressive stress has been measured by the determination of the bending of the substrate; a reduction of up to 50 % has been observed depending on the nitrogen content.
Structural Trends in Amorphous Carbon
Authors: Wang C. Z. , Ho K. M. 
Published: April 2011

ABSTRACTAmorphous carbon (a-C) structures over a wide range of densities are generated by tight-binding molecular dynamics simulations using the recently developed environment-dependent carbon tight-binding potential. Our simulation results show that the relative concentration of the sp2 and sp3 bondings in the a-C samples changes systematically with the density of the samples. The a-C networks obtained by quenching the low density liquids consist of mostly three-fold coordinated atoms while the diamond-like tetrahedral a-C can be generated by quenching the high density (about 3.0g/cm3) liquid carbon.
High Pressure Solid State Chemistry of A3(VO4)2 Compounds (A: Ca, Sr, Ba)
Authors: Grzechnik Andrzej , McMillan Paul F. 
Published: April 2011

ABSTRACTThe purpose of this study is to explore the potential of high pressure methods for preparation of new series of compounds in the A3(VO4)2 systems (A: Ca, Sr, Ba). In this study, we present our in situ vibrational and X-ray diffraction data on the behavior of the A3(VO4)2 compounds at high pressure and room temperature. Upon compression up to 290 kbar, there is no phase change in Ba3(VO4)2. Sr3(VO4)2 undergoes a first order phase transition to an olivine-like structure at about 150 kbar. In both the ambient pressure and olivine structures of Sr3(VO4)2, oxygen atoms form a hexagonal close packing. The packing in the olivine structure is distorted from this due to loss of 3-fold axis. Ca3(VO4)2 amorphizes at about 100 kbar. The high pressure behavior of the compounds studied here is related to the size of the A(2)2+ cations. Small Ca(2)2+ cations hinder the completion of crystal-to-crystal transformations in Ca3(VO4)2.
Temperature Dependence of the Intervalley Deformation Potential of GaAs/AlAs Superlattices Under Hydrostatic Pressure
Authors: Guha S. , Cai Q. , Chandrasekhar M. , Chandrasekhar H. R. , Kim Hyunjung , Alvarenga A. D. , Vogelgesang R. , Ramdas A. K. , Melloch M. R. 
Published: April 2011

ABSTRACTWe have studied the pressure dependence of the type-I and type-II transitions in (GaAs)m/(AlAs)m superlattices by photoluminescence (PL) spectroscopy. From the study of PL linewidths of the type-I exciton as a function of pressure and temperature, we determine the intervalley deformation potential. Beyond the type-I and type-II crossover, the PL linewidth increases both as a function of pressure and temperature. We find that the electron-phonon deformation potential for Γ-X intervalley scattering varies with temperature.
Electron Transport Properties of La1-xSrxTiO3 Under Hydrostatic Pressure
Authors: Hays Charles C. , Zhou Jianshi , Goodenough John B. , Markert John T. 
Published: April 2011

ABSTRACTThe temperature dependence of the resistance and thermoelectric power under hydrostatic pressure between 10 and 300 K are reported for two compositions, x = 0.044 and x = 0.05, of the narrowband system La1-xSrxTiO3. The application of hydrostatic pressure at room temperature induces a transition from a positive p-type to a negative n-type thermoelectric power for x = 0.044. This behavior is interpreted within a model of itinerant-electron antiferromagnetism in LaTiO3.
Metastable Melting Lines for H2O and the Liquid-Liquid Phase Transition Hypothesis
Authors: Mishima Osamu , Eugene Stanley H. 
Published: April 2011

ABSTRACTWhen ice Ih in an emulsion is compressed below 250 K, it melts to supercooled liquid water, avoiding the formation of other crystal phases. Here, we create emulsified high-pressure ices under high pressure and low temperature, and measure their temperature while these ices are decompressed at a constant rate at different temperatures. We detect metastable melting points of high-pressure ices, and identify their melting lines. We find what could be possibly two new ice phases, and discuss the relationship between decompression-induced melting and decompression-induced amorphization. Finally, we discuss briefly the analysis of experimental data and simulation results that are consistent with the hypothesized “second critical point” with temperature and pressure coordinates of approximately 200 K and 100 Mpa.