bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Auger and XPS Study on CVD and Natural Diamonds
Authors: Howe Jane Y. , Jones Linda E. , Braski David N. 
Published: April 2011

ABSTRACTCVD diamond films, ET 100 of Norton Diamond Film, were treateds in ultrahigh purity O2 from 420 to 575°C at 95 kPa. Auger and x-ray photoelectron spectra were collected from CVD and natural diamond surfaces. The Auger KVV line shapes of the CVD diamond with various surface conditions were compared to those of natural diamonds and sp2-bound graphite (HOPG) and glassy carbon. Comparisons were made on the peak shape of A1, which is the major satellite peak of carbon KVV. Auger KVV line shaped of oxidized CVD diamonds were more similar to that of natural diamond than either HOPG or glassy carbon. XPS is more sensitive to the change of surface chemisorbed species. The C Is binding energy of oxygenated and oxidized CVD diamonds (287.3 eV) was higher than that of natural diamond (285.7 eV), graphite (283.0 eV) and glassy carbon (284.2 eV). Auger and XPS findings indicated that when treated in O2 from 420 to 575°C at 95 kPa, direct oxidation of CVD diamond occurred without graphitization
Diameter Control in the Formation of Single-Wall Carbon Nanotubes
Authors: Sen Rahul , Ohtsuka Y. , Ishigaki T. , Kasuya D. , Suzuki S. , Kataura H. , Achiba Y. 
Published: April 2011

ABSTRACTSingle-wall carbon nanotubes (SWNTs) have been synthesized by laser ablation of Ni/Co catalyzed graphite target at 1200°C in argon gas. Raman spectroscopy has been used to study the effect of target position in the furnace and flow rate of argon gas on the diameter distribution of SWVNTs. It was found that yield of smaller diameter SWNTs relatively increases as target is placed away from the hot zone of the furnace. The relative yield of smaller diameter SWNTs decreases with increase in flow rate of the argon gas.
Amorphous Carbon-Silicon Alloys Prepared by a High Plasma Density Source
Authors: Ferrari A. C. , Racine B. , Morrison N. A. , Hutchings I. , Milne W. I. , Robertson J. 
Published: April 2011

ABSTRACTThe addition of silicon to hydrogenated amorphous carbon can have the advantageous effect of lowering the compressive stress, improving the thermal stability of its hydrogen and maintaining a low friction coefficient up to high humidity. Most experiments to date have been on a-C1-xSix:H alloys deposited by RF plasma enhanced chemical vapour deposition (PECVD). This method gives alloys with considerable hydrogen content and only moderate hardness. Here, we use a high plasma density source, the electron cyclotron wave resonance (ECWR) source, to prepare films with a high deposition rate. The composition and bonding in the alloys is determined by XPS, visible and UV Raman and FTIR spectroscopy. We find that it is possible to produce hard, low stress, low friction, almost humidity insensitive a-Cl. xSix:H alloys with a good optical transparency and a band gap over 2 eV.
In Situ Conductivity of Poly(3,4-Ethylenedioxythiophene) Electrosynthesized in Aqueous Solutions in the Presence of Large Anions
Authors: Ahonen H. J. , Lukkari J. , Kankare J. 
Published: April 2011

AbstractThick poly(3,4-ethylenedioxythiophene) films incorporating various anion dopants were anodically deposited from aqueous solutions. In situ AC conductometry was applied during the electropolymerisation and the conductivity values obtained in different electrolyte systems were compared. The results indicate that 3,4-ethylenedioxythiophene can be polymerised also from relatively dilute aqueous solutions containing various types of electrolytes and that the most conducting films are obtained using large organic anions.
High Dielectric Constant Polymer Ceramic Composites
Authors: Bai Y. , Bharti V. , Cheng Z.-Y. , Xu H. S. , Zhang Q. M. 
Published: April 2011

AbstractA new polymer-ceramic composite, using the newly developed relaxor ferroelectric polymer that has a high room temperature dielectric constant as the matrix, is reported. Different kinds of ceramic powders were studied and homogeneous composite thin films (20μm) were fabricated. It was observed that the increase of the dielectric constant of the composites with the ceramic content could be described quite well by the expression developed by Yamada et al., when the ceramic content is below 60% by volume. The experimental data shows that the relative dielectric constant of composites using PMN-PT powders can reach more than 250 with weak temperature dependence (i.e., the dielectric constant changes little in a broad temperature range). In addition to high permittivity, the composite prepared in clean environment also has high breakdown field strength (120MV/m), which yields an energy storage density more than 14J/cm3. The dielectric behavior of the composite at various frequencies was also studied and the results show that the material is promising for high frequency applications.
Synthesis and Electric Property of VDF/TrFE/HFP Terpolymers
Authors: Petchsuk A. , Chung T. C. 
Published: April 2011

AbstractThis paper focuses on the molecular structure-electric property relationships of VDF/TrFE/HFP terpolymers, containing vinylidene difluoride (VDF), trifluoroethylene (TrFE) and hexafluoropropene (HFP) units. Several terpolymers were synthesized and evaluated with the corresponding VDF/TrFE copolymers. In general, a small amount of bulky HFP units in the polymer chain prevents the long sequence of crystallization and results in smaller ferroelectric (polar) micro-domains, which show the improved electric properties. The resulting terpolymer possesses a interesting combined properties with good processibility, low Curie transition temperature and high dielectric constant, narrow polarization hysteresis loop, and high strain response (2.5%) at relatively low electric field (50 MV/m).
Superplastic Dome Forming of Machined Sheets
Authors: Akkus Nihat , Usugi Toshihiro , Kawahara Masanori , Manabe Ken-ichi , Nishimura Hisashi 
Published: April 2011

AbstractAn experimental work on the superplastic bulge forming of machined sheets is presented in this study. Unlike the previously employed incremental-iterative method, a reverse deformation model was used to estimate the initial thickness distribution of the machined sheets from which a constant final thickness can be obtained when the shape of the bulged sheet is hemisphere. The reverse deformation modci was obtained by modifying previously-known models, which were based on the axisymmetric membrane and the incremental strain theory.Bulge forming experiments were conducted on machined sheets of Al alloy, A5083, at about 530°C under constant pressure control mode. The result of this simulation to estimate the final constant thickness distribution agreed well with the experiment, and confirmed that the reverse deformation model can be successfully applied in optimizing the thickness distribution of the starting sheets in order to obtain the desired final thickness distribution of the free bulged hemispherical product.
Effect of SN Additions on Superplasticity in Al-Mg-Mn-Sc Alloys
Authors: Henager C. H. , Vetrano J. S. , Gertsman V. Y. , Bruemmer S. M. 
Published: April 2011

AbstractIdentical Al-Mg-Mn-Sc alloys without and with 0.034-wt% Sn additions were fabricated, heat-treated, and tensile tested in a fine-grain (d < 6 pm) condition at four strain rates from 10−2to 10−4s−1and at temperatures from 723K to 823K. Alloys with Sn additions exhibited reduced failure strains at 723K but higher failure strains at 823K for the slowest strain rates. The effect of Sn on flow stress, activation energy for flow stress, and strain rate exponent was explored and was found to be small. The main effect of Sn was suggested to be in reducing cavitation by allowing a redistribution of stress at critical hetero-junctions in the alloys.
Superplasticity of Nickel-Based Alloys with Micro- and Sub-Microcrystalline Structures
Authors: Valitov V.A. , Bewlay B.P. , Mukhtarov Sh. Kh. , Kaibyshev O.A. , Gigliotti M.F.X. 
Published: April 2011

AbstractThis paper will describe the generation of micro- and sub-microcrystalline structures in two Ni-based alloys that are typically strengthened by phases, such as γ′ and γ″+δ. The relationship between the superplastic behavior and microstructure will be discussed. High strain deformation processing in the temperature range of 0.9 Tm to 0. 6Tm results in reduction of the initial coarse-grained structure (>100 µm) to a range of structures including microcrystalline (MC) (grain size <10 µm) and sub-microcrystalline (SMC) (grain size <1 µm) with increasing deformation. The influence of alloy chemistry and constituent phases on dynamic and static recrystallization is considered, and their effect on grain refinement is described. Low-temperature and high strain rate superplasticity can be observed in dispersionstrengthened alloys with SMC structures. It was established that in dispersion-hardened Ni alloys with SMC structures, superplasticity can be observed at temperatures 200-250°C lower than in alloys with MC structure.
Formation and Characterization of Single Crystal Ni2MnGa Thin Films
Authors: Dong J. W. , Chen L. C. , Mckernan S. , Xie J. Q. , Figus M. T. , James R. D. , Palmstrøm C. J. 
Published: April 2011

AbstractIn this paper, molecular beam epitaxial growth of Ni2MnGa single crystal layers on GaAs (001) using a NiGa interlayer is reported. X-ray diffraction and transmission electron microscopy confirmed an epitaxial relationship of Ni2MnGa [100]“010] // GaAs [100] [010] and a tetragonal structure of the film (a = b = 5.79 Å, c = 6.07 Å). Magnetic measurements using vibrating sample and superconducting quantum interference device magnetometers revealed an in-plane magnetization of ∼200 emu/cm3at room temperature and a Curie temperature of ∼350 K. The martensitic phase transformation was observed to occur at ∼250 K
Effects of Electric Fields on the Bending Behavior of Piezoelectric Composite Laminates
Authors: Cheng J.Q , Zhang T.Y. , Zhao M.H. , Qian C.F. , Lee S. W. R. , Tong P. 
Published: April 2011

AbstractThis Paper investigates the bending behavior of piezoelectric laminates under combined mechanical and electrical loading. The laminate has a PZT - 5H ceramic core sandwiched by graphite/epoxy plates. Three-point bending tests and in-situ acoustic emission measurements were conducted on the PZT-5H laminates preloaded by an applied electric field. The results show that the PZT-5H core fractures first and then delaminaton occurs along the tensile stressed interface between the PZT ceremic and the graphite/epoxy layer. Finite element analysis was performed to analyze stresses in the sandwich structure under combined mechanical and electrical loading. Consequently, the bending strength of the PZT core was evaluated from the experiment data. The electric field, either positive or negative, reduces the fracture strength of the pzt core.
Considerations in the Development of a Piezoelectric Transducer Cochlear Implant
Authors: Mukherjee N. , Roseman R. D. 
Published: April 2011

AbstractSensorineural hearing loss results from the inability of the inner ear cochlear organ of Corti to transduce mechanical energy incident in the cochlea to electrical signals in auditory nerve fibers. Cochlear implant devices are used to alleviate this condition. Piezoelectric materials offer the unique scope of functioning as cochlear implants, possibly enabling simplification of the process of electrical stimulation and enhancing knowledge of the workings of both the healthy and artificially stimulated inner ear. The requirements imposed on such a device are discussed. It is believed that flexible piezoelectric PVDF and ceramic-polymer composites are best suited for this application. The design of a device which utilizes the bending piezoelectric mode, and results of testing the same in air are presented. Present work is aimed at understanding the fundamental dynamic piezoelectric properties in this mode and is expected to result in a device suitable forin vitroandin vivotesting.
Characterization of Low Temperature, Wafer-Level Gold-Gold Thermocompression Bonds
Authors: Tsau Christine H. , Schmidt Martin A. , Spearing S. Mark 
Published: April 2011

AbstractLow temperature, wafer-level bonding offers several advantages in MEMS packaging, such as device protection during aggressive processing/handling and the possibility of vacuum sealing. Although thermocompression bonding can be achieved with a variety of metals, gold is often preferred because of its acceptance in die bonding [1] and its resistance to oxidation. This study demonstrates that the simultaneous application of moderate pressure (0.5 MPa) and temperature (300°C) produces strong wafer-level bonds. A four-point benddelamination technique was utilized to quantify bond toughness. Test specimens exhibited constant load versus displacement behavior during steady state crack propagation. Two distinct fracture modes were observed: cohesive failure within the Au and adhesive failure at the Ti-Si interface. The strain energy release rate for Au-Au fracture was found to be higher than that associated with Ti-Si fracture, consistent with the greater plastic deformation that occurs in the metal during fracture.
Fracture Behavior of Micro-Sized Ni-P Amorphous Alloy Specimens
Authors: Ichikawa Y. , Maekawa S. , Takashima K. , Shimojo M. , Higo Y. , Swain M. V. 
Published: April 2011

AbstractFracture behavior of micro-sized Ni-P Amorphous alloy specimens has been investigated using a newly developed mechanical testing machine. Specimens with dimensions of 10 × 12 × 50 μm were prepared by focused ion beam machining. Two types of specimens with different crack geometries were prepared. One specimen has a notch with root radius is 0.25 μtm and the other has a fatigue pre-crack. The shapes of the loaddisplacement curves are different for each type of specimen. The fracture strength of the specimens with a notch is higher than that with a fatigue pre-crack and the fracture surfaces of the specimens are also different for each type of specimen. This may be due to the difference in stress concentration at the crack (notch) tip, and indicates that even a notch with a root radius of 0.25 μm is not able to be regarded as a crack for micro-sized specimens. Therefore, the introduction of a fatigue pre-crack is essential for the evaluation of fracture toughness for such micro-sized specimens.
Low Temperature Thermal Chemical Vapor Deposition of Silicon Nitride Thin Films for Microelectronics Applications
Authors: Skordas Spyridon , Sirinakis George , Yu Wen , Wu Di , Efstathiadis Haralabos , Kaloyeros Alain E. 
Published: April 2011

AbstractSilicon nitride technology has been incorporated in ultra-large scale integration (ULSI) microchip fabrication, thin film transistors (TFT), solar cells, and many other applications in a rapidly expanding market. Nevertheless, silicon nitride technologies currently in use face considerable limitations. Low pressure chemical vapor deposition (LPCVD) occurs at relatively high temperature (>700 °C) and plasma enhanced chemical vapor deposition (PECVD), although occurring at temperatures below 300 °C, produces hydrogen-rich films and could be self-limiting in terms of conformality and damage to the devices due to ion bombardment. In the present work, successful low temperature thermal chemical vapor deposition (LTCVD) of silicon nitride is reported on 8” silicon wafers. The use of a halide-based silicon precursor, tetraiodosilane (SiI4) has led to the deposition of high quality silicon nitride thin films at temperatures as low as 300 °C.Characterization of resulting film properties has been performed to determine their dependence on deposition parameters by Auger Electron Spectroscopy (AES), Rutherford Backscattering Spectroscopy (RBS), Fourier Transform Infrared (FTIR), Nuclear Reaction Analysis (NRA), Ellipsometry, Capacitance-Voltage (C-V), and Current-Voltage (I-V) measurements.
Volatile Liquid Precursors for the Chemical Vapor Deposition (CVD) of Thin Films Containing Alkali Metals
Authors: Broomhall-Dillard Randy N. R. , Gordon Roy G. , Wagner Valerie A. 
Published: April 2011

AbstractThe first volatile, liquid compounds of alkali metals were synthesized and used for the CVD of materials containing alkali metals. Amides of the type MNR1(SiMe2R2) and MN(SiMe2R2)2 [M = Li, Na, K; R1= t-butyl, t-amyl; R2= ethyl, n-propyl, i-propyl, n-butyl, i-butyl, n-hexyl, n-octyl] were made and characterized. The lithium amides were prepared via the deprotonation of the parent amine using butyl lithium. The sodium and potassium amides were formed by transamination of sodium amide and potassium bis(trimethylsilyl)amide with the parent amines. For example, lithium bis(ethyldimethylsilyl)amide was prepared from butyl lithium and bis(ethyldimethylsilyl)amine and was distilled as a clear, colorless liquid at 122 °C (0.2 Torr) having a viscosity of 37 cP at 40 °C. These alkali metal amides can be used as convenient liquid sources for CVD of mixed metal oxides containing alkali metals, such as the non-linear optical material lithium niobate, lithium-containing materials for battery electrodes, electrochromic tungsten bronzes, and the pyroelectric and ferroelectric material potassium tantalate.
Chemical Vapor Deposition of Conformal Alumina Thin Films
Authors: Fahlman Bradley D. , Barron Andrew R. 
Published: April 2011

AbstractDeposition of highly conformal alumina thin films has been carried out by hydrolysis of the liquid alane precursor, AlH3(NMe2Et). Deposition onto Si wafers, quartz and carbon fibers were all carried out utilizing a hot-wall atmospheric pressure chemical vapor deposition (APCVD) system, while deposition onto ceramic particles was accomplished in a simple fluidized-bed APCVD reactor. Films were characterized by SEM, microprobe and electrical conductivity measurements. Growth rates were on the order of 40 - 80 Å.min−1at 165 °C. The conformality of the films was illustrated using silicon wafers that were etched prior to deposition.
Emissivity Compensated Pyrometry of the Substrate Surface During Movpe Growth of InxGa1−xAs1−yPy/InP Materials in Rotating Disc Reactors
Authors: Ramer J. , Patel B. , Patel A. , Boguslavskiy V. , Gurary A. 
Published: April 2011

AbstractIn order to overcome some of the inherent difficulties with applying conventional pyrometry to production scale rotating disc MOVPE reactors, the in-situ technique of emissivity compensated pyrometry has been applied. Due to the extreme temperature sensitivity of epitaxial processes involving InxGa1−xAs1−yPy, this material system provides the optimum proving grounds for this technology. With this temperature measurement technique, we have developed a method for measuring the temperature of the substrate during MOVPE growth in high speed rotating disc reactors that does not require any modification to the reactor hardware. Real world testing, during the growth of complex epitaxial structures involving the highly temperature sensitive InxGa1−xAs1−yPy quaternary, indicates a very strong correlation between the measured temperature of the substrate during growth, and actual epitaxial wafer measurements after growth. This temperature measurement system can be used to maintain the wavelength of the InxGa1−xAs1−yPy quaternary materials within a range of 2 nm.
Recent Progress of Mid-IR Type-II Interband Cascade Lasers
Authors: Lin Chlh-Hsiang , Hwang W.-Y. , Zaitsev S. V. , Urn J. , Kuo C.H. , Delaney A. , Zheng Jun , Murry S. J. , Liu A. , Le H. Q. , Mu Y. , Pei S. S. 
Published: April 2011

AbstractWe report the recent progress in type-II interband cascade (IC) lasers, For the 4.2-pm devices, lasing was observed up to 210 K, and the threshold density was only 95 A/cm2at 90 K and 284 A/cm2at 200 K. For the 4.5-μm lasers, the internal loss was only 11.6 cm−1 and the internal quantum efficiency was 460% at 90 K. We have also demonstrated the first dual-wavelength type-II IC lasers at 4.482 and 4.568 μm.
Native Defect Characterization in ZnGeP2
Authors: Hoffmann A. , Born H. , Näser A. , Gehlhoff W. , Maffetone J. , Perlov D. , Ruderman W. , Zwieback I. , Dietz N. , Bachmann K. J. 
Published: April 2011

AbstractElectron paramagnetic resonance (EPR) as well as time-resolved and time-integrated photoluminescence (PL) are used to characterize the defect centers in ZnGeP2 bulk crystals. The samples, as-grown, electron-irradiated and annealed, reveal a strong intensity dependence of the VZn-correlated EPR-transitions. Photo-EPR experiments show that this intensity behavior is mainly caused by a recharging of the VZn centers owing to the preparation induced shift of the Fermi-level. The luminescence spectra show a broad infrared emission with peak position at 1.23 eV that exhibits features of classical donor-acceptor recombination. The hyperbolic decay characteristics, investigated in energy range from 1.2 eV up to 1.5eV, suggest that this broad emission band is related to one energetic recombination center. This recombination is interpreted to be between donor-acceptor states related to residual disorder on the cation sublattice that is retained in metastable equilibrium during the formation of the chalcopyrite structure. The emission decay behavior in the energy range from 1.2 eV up to 1.6 eV is characterized by two hyperbolic time constants, and explained as the super-composition of the decays from the broad emission center peaked at 1.2 eV and an additional donor-acceptor recombination centers at 1.4 eV.
Photoresponse of Tellurium Rich TexSe(1−x) Nonlinear Optical Semiconductors
Authors: Brown G. J. , Dennis Cindi L. , Ohmer M. C. , Burger Arnold 
Published: April 2011

AbstractThe optical properties of TexSe(1−x) were studied for x = 0.8, 0.9, and 1.0. The results for variable temperature, polarization sensitive, spectral photoconductivity measurements on oriented single crystals, as well as the energy band gaps and their temperature dependencies are presented. In all cases, the band gap was found to increase with increasing temperature. Analytical expressions describing the temperature dependent behavior are reported. Furthermore, for the first time the characteristic two peak spectrum of tellurium was separated into its two components for incident radiation polarized parallel and perpendicular to the c-axis as a function of temperature. However, two distinct peaks were not discernible in the alloys, with or without polarization, although the signal intensity was slightly polarization dependent.
Temperature Dependent Hall Measurements on CdGeAs2
Authors: Ptak A.J. , Jain S. , Stevens K.T , Myers T.H. , Schunemann P.G. , Setzler S.D. , Pollak T.M. 
Published: April 2011

AbstractSeventeen samples of CdGeAs2 have been extensively characterized by temperature-dependent Hall effect and resistivity measurements. Due to the anisotropic nature of the electrical properties, carefully matched sample sets were fabricated with the c-axis either in or out of the plane of the sample. The matched samples allowed determination of carrier concentration and both in-plane and out-of-plane mobilities as a function of temperature. The electrical properties of both undoped and lightly doped samples were dominated by either native defects or residual growth impurities, leading to compensated p-type material. N-type doped material was obtained only with heavy doping. An apparent variation in acceptor activation energy between 110 and 165 meV could be best explained in terms of two deep acceptor levels and at least one shallow donor. Room temperature absorption coefficient data and the relation to background doping is also reported.