bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation Of Cracking Mechanisms Of Plasma Sprayed Alumina-13% Titania By Acoustic Emission
Authors: Lin C.K. , Leigh S.H. , Gansert R.V. , Murakami K. , Sampath S. , Herman H. , Berndt C.C. 
Published: April 2011

AbstractFree standing alumina-13% titania samples were manufactured using high power water stabilized plasma spraying. Heat treatment was performed at 1450°C for 24 hours and then at 1100°C for another 24 hours. Four point bend tests were performed on the as-sprayed and heat-treated samples in both cross section and in-plane orientations with in situ acoustic emission monitoring to monitor the cracking during the tests. Catastrophic failure with less evidence of microcracking was observed for as-sprayed samples. Energy and amplitude distributions were examined to discriminated micro- and macro-cracks. It was found that the high energy (> 100) and high amplitude (say > 60 dB) responses can be characterized as macro-cracks. Physical models are proposed to interpret the AE responses under different test conditions so that the cracking mechanisms can be better understood.
Parallel Simulations Of Rapid Fracture
Authors: Abraham Farid F. 
Published: April 2011

AbstractImplementing molecular dynamics on the IBM SP2 parallel computer, we have studied the fracture of two-dimensional notched solids under tension using million atom systems. Brittle materials are modelled through the choice of interatomic potential function and the speed of the failure process, and our interest is to learn about the dynamics of crack propagation in ideal materials. Recent laboratory findings occur in our simulation experiments, one of the most intriguing is the dynamic instability of the crack tip as it approaches a fraction of the sound speed. A detailed comparison between laboratory and computer experiments is presented, and microscopic processes are identified. In particular, an explanation for the limiting velocity of the crack being significantly less than the theoretical limit is provided.
Temporal Instabilities (Dissipative Structures) In Cyclically Deformed Metallic Alloys
Authors: Glazov Michael V. , Williams David R. , Laird Campbell 
Published: April 2011

AbstractThe existing models for the “classical” Portevin-Le-Chatelier effect have been analyzed, and the non-linear dynamical model has been proposed in order to quantify the nature of temporal instabilities in fatigued metallic alloys. The model employs the concept of a positive feed-back among the populations of mobile, immobile and Cottrell-type dislocations with atmospheres of point defects. Three major types of loading have been numerically simulated: pure sinusoidal, creep fatigue (“the Lorenzo-Laird bursts”) and ramp loading (“the Neumann bursts”, when the amplitude of otherwise cyclic loading grows linearly with time). Computer movies of the temporal evolution of stress and dislocation densities have been prepared as an aide for analysis and illustration. The model successfully reproduces stress serrations in terms of the underlying dislocation mechanisms and thus for the first time establishes a fundamental link between the micro-and macromechanics of cyclic deformation.
Plan-View Transmission Electron Microscopy Of Crack Tips In Bulk Materials
Authors: Saka H. , Nagaya G. , Sakuishi T. , Abe S. , Muroga A. 
Published: April 2011

AbstractA focused ion beam (FIB) system has been applied to prepare a thin foil specimen of Si, MgO and alumina which contained cracks in the plane of foil. It was possible to observe a much larger area at and near a crack tip than has been hitherto possible. FIB was also applied to observation of microstructure near a crack tip evolved during severe rolling contact fatigue in a steel.
New Routes To Nitrides: Synthesis Of A Highly Colored Lithium Tantalum Oxynitride
Authors: Houmes Joel D. , Loye Hans-Conrad Zur 
Published: April 2011

ABSTRACTThe synthesis of a new lithium tantalum oxynitride is described. The compound, LiTaO3-3xN2x was synthesized by reacting LiTaO3 with anhydrous ammonia at temperatures ranging from 773 K to 1173 K. Depending on the reaction temperature the sample color changes from white to tan (773 K) to bright orange (973 K) to red (1123 K). The color appears to be the result of a p-d transition consistent with a charge transfer from localized nitrogen states to a band of predominately metal character. Electrical and magnetic measurements indicate that the material is a diamagnetic insulator.
Synthesis and Modification of beta-C3N4 Materials by Ion-beam Processing
Authors: Ren Zhong-Min , Du Yuan-Cheng , Ying Zhi-Feng , Li Fu-Ming , Zhang Yafei 
Published: April 2011

ABSTRACTCovalent carbon nitride films have been synthesized by laser ablation and ion-beam coprocessing. Different laser ablations give different ablated graphite plasma. Beta- C3N4 polycrystalline has been found in the deposited films. Under laser energy of 50 mJ per pulse, the adoption of 532 nm laser used for ablation of graphite is proposed for the purpose of production of good carbon nitride films. The C-N crystal structures can be improved by followed ion-beam processing.
Epitaxial Growth of 3C-SiC by Pulsed Laser Deposition
Authors: Cosgrove J. E. , Rosenthal P. A. , Hamblen D. , Fenner D. B. , Yang C. 
Published: April 2011

ABSTRACTWe have grown thin films of SiC by pulsed laser deposition on silicon (100) and vicinal and non-vicinal 6H SiC (0001) substrates using a quadrupled YAG laser and a high purity dense polycrystalline SiC target. Epitaxy on all three substrate types was confirmed by x-ray diffraction, transmission electron microscopy and electron diffraction. Composition of the films was measured by Rutherford backscattering spectrometry and Scanning Auger Microprobe.
The Interaction of HCl With polycrystalline β-SiC: Evidence for a Site-Blocking Mechanism for HCl Inhibition of SiC CVD
Authors: Schulberg Michelle T. , Allendorf Mark D. , Outka Duane A. 
Published: April 2011

ABSTRACTChlorine-containing precursors are attractive for chemical vapor deposition (CVD) of SiC because they are less hazardous and more economical than silane precursors. The reactivity of HCl, a by-product of these reactions, on SiC is of particular interest because it has been reported that HCl inhibits SiC CVD, but the mechanism for this inhibition has not been identified. In this work the adsorption of HCl on polycrystalline β-SiC was examined with Auger Electron Spectroscopy (AES) and Temperature Programmed Desorption (TPD). HCl adsorbs readily on SiC, with an initial sticking probability of 0.1 at 300 K, and forms a strong bond, with an activation energy for desorption of 64 kcal/mol. The only product detected by TPD is HCl, which desorbs in a peak centered at 1010 K. There are no Si- or C-containing desorption products, demonstrating that HCl does not etch SiC under TPD conditions. These results are consistent with a site-blocking mechanism for HCl inhibition of SiC CVD, but not with an etching mechanism.
Plasma Surface Modification in Biomedical Applications
Authors: Loh I-H , Sheu M-S 
Published: April 2011

AbstractSynthetic biomaterials are widely used for a variety of in vivo and in vitro biomedical applications. However, the performance, safety, and cost effectiveness of medical products are determined by desirable interactions between the physiological environments and biomaterial surfaces. Hence, development of surface modifications for biomaterials is strongly demanded by the biomedical industry. High energy techniques, such as glow discharge plasma, have been developed to impart specific chemical functionality to the biomaterial surfaces or to deposit new polymer films with desired properties. The use of plasma surface modification for biomedical applications is reviewed in this paper.
Vertically-Stacked InAs Islands Between GaAs Barriers Grown by Chemical Beam Epitaxy
Authors: Miller Mark , Jeppesen Søren , Georgsson Kristina , Kowalski Bernhard , Malm Jan-Olle , Pistol Mats-Erik , Samuelson Lars 
Published: April 2011

AbstractWe report vertically-aligned InAs islands separated by GaAs barriers thin enough for electronic coupling. Thinner barriers reduced the InAs critical-thickness for island formation. Transmission electron microscopy revealed well-aligned islands with all detected islands in complete stacks. Atomic force microscopy showed the top islands of uncapped stacks are fully formed. The photoluminescence peak was sharper and shifted to lower energy compared to a single-layer growth. We attribute this shift to island-to-island electronic coupling and to the smaller compressive strain in the center of the composite structure.
Temperature-Dependent Strain Relaxation and Islanding of Ge/Si(111)
Authors: Deelman P. W. , Schowalter L. J. , Thundat T. 
Published: April 2011

AbstractIn order to understand Ge island nucleation and evolution, we have studied strain relaxation and clustering of Ge grown on Si(111) by molecular beam epitaxy (MBE) with in situ reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and Rutherford backscattering spectrometry (RBS). Our goal is to tailor the size and density of the nanocrystals by controlling thermodynamics and kinetics. At low temperature (∼ 450°C), we observe a sharp 2D–3D growth mode transition after 2.5ML ±0.1ML (we define a thickness of 1ML to be one-third the length of the body diagonal of the Ge conventional unit cell), when transmission diffraction features appear in RHEED and the surface lattice constant begins to relax. The mechanisms of island growth and strain relaxation change with growth temperature. At ∼ 700°C, transmission diffraction spots never appear in RHEED for Ge/Si(111) and strain relaxation occurs gradually. After 37ML of growth, the apparent in-plane lattice parameter increases only 1.5% over that of the Si substrate. This behavior is explained by the different manner in which islands initially nucleate and grow in the two temperature regimes. At low temperature, small islands nucleate and grow on a relatively rough wetting layer (which itself provides preferential sites for dislocation introduction). The areal density of the small islands is relatively high. At high temperature, a small number of islands grow very large from the outset. A general model indicates how, at low temperature. The relative difficulty of overcoming the barrier to dislocation formation actually results in an apparent larger degree of strain relief than at high temperature.
Optical Characteristics of Tensilely Strained GaInP/AIGaInP Mqw for Laser Diode Applications
Authors: Ono K. , Motoda T. , Tsugami M. , Hayafuji N. , Sonoda T. , Takamiya S. 
Published: April 2011

AbstractAvailability of tensilely strained GaInP/AIGaInP quantum well, which is essential to laser diodes operating at 635–650nm, is investigated by combining conventional and time-resolved photoluminescence measurements. It is found that optical characteristics are improved by introducing tensile strain into barrier layers in addition to well layers, while samples with unstrained or compressively strained barrier layers reveal inferior characteristics. Experimantal data indicate that these optical characteristics are not determined by interfacial stress, but by the energy band discontinuity between well and barrier layer.
Improved Copper Chemical Vapor Deposition Process by Applying Substrate Bias
Authors: Lee Won-Jun , Rha Sa-Kyun , Lee Seung-Yun , Kim Dong-Won , Chun Soung-Soon , Park Chong-Ook 
Published: April 2011

AbstractThe substrate bias was applied during the chemical vapor deposition (CVD) process of copper in an effort to change the adsorption behaviors of the reactant. Copper films were deposited on TiN and SiO2 from Cu(hfac)(tmvs) with the substrate bias and without one. The surface morphology, the thickness, the sheet resistance and the purity of the films were investigated. When the negative substrate bias of -30 V was applied to the substrate, the deposition rate of copper increased both on TiN and SiO2. No change was observed in the chemical composition of the copper film deposited with substrate bias in comparison with that of the copper film deposited with no bias. It was calculated that Cu(hfac) has the dipole moment whose direction is from copper to hfac. Under the d. c.electric field, dipole tends to align along the poling direction. Resulting from the overlapping population (OP) value analysis, the improvement of deposition rate under negative substrate bias was explained due to the adsorption of copper atom in Cu(hfac) species directly onto the substrate by the electric field applied between the substrate and the gas showerhead.
A Complete Stochastic Wiring Distribution for Gigascale Integration (GSI)
Authors: Davis Jeffrey A. , Eble John C. , De Vivek K. , Meindl James D. 
Published: April 2011

AbstractBased on Rent's Rule, a well established empirical relationship, a rigorous derivation of a complete wire length distribution for on-chip random logic networks is performed. The distribution is then used to describe an optimal architecture for a multilevel wiring network that provides maximum interconnect density and minimum chip size for a ULSI system. In addition, this new distribution has been incorporated into a Generic System Simulator (GENESYS), that projects overall performance of future ULSI systems. Assuming various interconnect materials such as copper, aluminum, silicon dioxide, and low dielectric polymers, GENESYS has been used to examine the effects that each material has on overall performance of ASIC's over the next 15 years.
New Surface Cleaning Method for Heavily-Doped Silicon and Its Application to Selective Cvd-W Clad Layer Formation on Single- and Poly-Crystalline Silicon
Authors: Kosugi T. , Sato Y , Ishii H. , Arita Y 
Published: April 2011

AbstractWe have developed a new method of cleaning p+-Si surfaces by plasma hydrogenation and subsequent HF treatment prior to selective W-CVD by SiH4 reduction. The hydrogenation enhances the hydrogen-termination of p+-Si surfaces in HF solution significantly, resulting in high controllability in selective W-CVD on p+-Si surfaces. Contact resistivity was 0.5 to 3×10-7 Ω cm2 for single- and poly-crystalline p+-Si. The increase in junction leakage current was fairly small because of low Si consumption.
Chemical Vapor Deposition of Tin for Ulsi Applications
Authors: Eizenberg M. 
Published: April 2011

AbstractTiN has been recognized as an excellent barrier material for W as well as Al planarization gap filling of contacts and vias. The need for conformality over extreme topography necessitates the use of CVD rather than sputtering for the deposition of TiN. In this paper we will first review the various deposition techniques of CVD TiN. Then, we will present a recently developed approach: thermal decomposition of TDMAT followed by nitrogen-based rf plasma treatments for resistivity reduction. This approach utilizes the advantages of thermal decomposition: excellent step coverage, good barrier properties, and low particle content. The resistivity reduction of the post deposition plasma treatment is followed by excellent stability upon long term air exposure. Vias and salicide contacts utilizing this unique process exhibit resistance values equivalent to those obtained when sputtered TiN is used. Conformal films as thin as 200Å can be utilized as excellent barriers for deep sub-0.5μm devices with large aspect ratios, where sputtered TiN can not be used any more.
Thermal Metalorganic Chemical Vapor Deposition of Ti-Si-N Films for Diffusion Barrier Applications
Authors: Custer J. S. , Smith Paul Martin , Jones Ronald V. , Maverick A. W. , Roberts D. A. , Norman J. A. T. , Hochberg A. K. 
Published: April 2011

AbstractStructurally disordered refractory ternary films such as titanium silicon nitride (Ti-Si-N) have potential as advanced diffusion barriers in future ULSI metallization schemes. Here we present results on purely thermal metalorganic chemical vapor deposition (CVD) of Ti-Si-N. At temperatures between 300 and 450°C, tetrakis(diethylamido)titanium (TDEAT), silane, and ammonia react to grow Ti-Si-N films with Si contents of 0-20 at.%. Typical impurity contents are 5-10 at.%H and 0.5 to 1.5 at.% C, with no O or other impurities detected in the bulk of the film. Although the film resistivity increases with increasing Si content, it remains below 1000 μΩ-cm for films with less than 5 at.% Si. These films are promising candidates for advanced diffusion barriers.
X-Ray Microdiffraction for VLSI
Authors: Wang P.-C. , Cargill G. S. , Noyan I. C. , Liniger E. G. , Hu C.-K. , Lee K. Y. 
Published: April 2011

AbstractWe describe how x-ray microbeam diffraction is being used to measure strain with micronscale spatial resolution. Micron-scale x-ray beams can be obtained using tapered glass capillaries. With the high brightness and broad energy spectrum of synchrotron radiation and the energy dispersive capabilities of commercially available, liquid nitrogen cooled x-ray detectors, spatially resolved strains in a sample can be determined along different directions without having to rotate the sample, in contrast with more conventional methods using monochromatic x-ray diffraction. This is a major advantage in achieving micron-scale spatial resolution. Strain sensitivities on the order of 2×10−4 have been achieved in such measurements. White beam x-ray microdiffraction has been applied for the first time in real-time studies of thermal and electromigration related strain distributions in passivated Al-on-Si conductor lines. Results of measurements on a single 10μm-wide line are described.
Synthesis and Characterization of Siof Thin Films Deposited by Ecrcvd for Ulsi Multilevel Interconnections
Authors: Lee Seoghyeong , Park Jong-Wan 
Published: April 2011

AbstractLow dielectric constant fluorine doped silicon oxide films were deposited by using ECR plasma CVD with SiF4 and O2 as source gases diluted in Ar gas. Characterization of films was carried out in terms of various gas flow ratios (SiF4/O2 = 0.2 ∼ 1.6). The microwave power and substrate temperature during deposition were fixed at 700W and 300°C, respectively. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTIR), fluorine concentration by X-ray photoelectron spectroscopy (XPS) and refractive index by ellipsometry. Dielectric constant was determined from C-V measurements at 1MHz. FTIR spectra shows that as the fluorine concentration increases, peak intensities of Si-F bonding and shoulder peak at around 1160cm−1 of Si-O stretching mode increased. Moreover, with increasing the fluorine concentration in the SiOF film, the peak position of Si-O stretching mode shifts to the higher wavenumber side. The Si-F2 bond peak is observed to rise when the SiF4/O2 gas flow ratio is larger than 1.0. Refractive index and film density decreased with increasing the SiF4/O2 gas flow ratio. The SiOF film deposited at SiF4/O2 gas flow ratio of 1.0 exhibited fluorine content of 11.8 at.% and dielectric constant of 3.14.
The Band at “960”
Authors: Schwarz S. , Corbin D. R. , Vega A. J. 
Published: April 2011

AbstractMesoporous silicas were modified with titanium alkoxide precursors. Results are consistent with a model that describes the resultant silica surface as a mixture of Si–OH groups, isolated Si–O–Ti type species, and oligomeric (-Ti-O-)n ensembles. Decreasing the rate of hydrolysis of the precursor by using chelated Ti-alkoxides increases the fraction of isolated Ti.
Preparation of Continuous Mesoporous Films on Porous and Dense Substrates
Authors: Liu J. , Bontha J. R. , Kim A. Y. , Baskaran S. 
Published: April 2011

AbstractHigh quality, continuous mesoporous films are prepared on both porous and dense substrates. An interfacial reaction mechanism is used to grow mesoporous films within the pores of porous supports using a diffusion cell reactor. The porous support was placed between two compartments containing a silicate solution in one compartment and a surfactant solution in the other. The silicate and surfactant solutions diffused into the support to form a mesoporous film at the liquid-liquid interface. This method produces a transparent film free from large defects. Spincoating technique is also used to prepare mesoporous films on dense substrates. These films have uniform thickness and show well-defined interference depending on the film thickness.
Nanostructural Study of Luminescent Porous Polycrystalline Silicon
Authors: Poon M. C. , Han P. G. , Sin J. K. O. , Wong H. 
Published: April 2011

AbstractLuminescent porous poly-Si films with large areas or micron-sized patterns have been obtained by anodization or stain etching of phosphorus-doped poly-Si films deposited by low pressure chemical vapor deposition onto Si, thermal oxide or CVD nitride. The anodized film is composed of spherical Si grains with nano-pores formed around the surface. However, the stainetched film has large rectangular Si grains, and no nano-pores can be observed. The intensity of photoluminescence is enhanced after nitric acid boiling or stain etching, and is found to be closely related to the crystallinity of the porous Si layers.
Synthesis, Characterization and Catalytic Properties of Al2O3-TiO2 Mixed Oxides Prepared by Sol-Gel
Authors: Montoya A. , Melé;ndez-Hernindez J. , Domínguez J. M. , Sandoval-Robles G. 
Published: April 2011

AbstractSome synthesis parameters like R-OH/OBu, H20/OBu and composition (Al/Ti) ratios influence the textural and catalytic properties of the mixed Al2O3 -TiO2 oxides. The Radial Distribution Function of the pure and mixed oxides shows that Ti4+ incorporation favors the long-range-order in the mixed aggregates as well as the surface area loss at high temperatures, i.e. 900 °C. The catalytic dehydration of isopropanol towards propylene and the HDS of light gasoils indicate that catalytic properties of the sol-gel mixtures are comparable to the activity of reference catalysts, i.e. Al2O3and Ni/Al2O3.
Sol-Gel Processed Alumina based Materials in Microcalorimeter Sensor Device Fabrication for Automotive Applications
Authors: Nakouzi S. R. , McBride J. R. , Nietering K. E. , Narula C. K. 
Published: April 2011

AbstractThe application of sol-gel processed materials in a variety of sensors has been proposed. We describe microcalorimeter sensor devices employing sol-gel processed alumina based materials which can be used to monitor pollutants in automotive exhaust. These sensors operate by measuring changes in resistance upon catalysis and are economically acceptable for automotive applications. It is important to point out that automobiles will be required to have a means of monitoring exhaust gases by on-board sensors as mandated by the EPA and the California Air Resources Board (OBD-II).
Optical Interference Filters Made of Porous Silicon
Authors: Thönissen M. , Berger M. G. , Krüger M. , Billat S. , Arens-Fischer R. , Glück O. , Lüth H. , Hilbrich S. , Theiss W. , Grosse P. 
Published: April 2011

AbstractPorous silicon (PS) layers can easily be formed by an electrochemical etch process using a mixture of hydrofluoric acid (HF) and ethanol. The microstructure and porosity of the layers depend on the HF concentration, the doping level of the substrate and the current density applied during the etch process. Changing the current density during the etch process will result in a well defined layer structure consisting of layers with different porosities. Each single layer can be treated as an effective medium exhibiting a refractive index depending mainly on the porosity of the layer. Using reflectance measurements we have investigated the dependence of the refractive index of PS layers on the formation current density for different substrates. In addition the etch rate was determined by thickness measurements with an electron microscope. Based on these results various kinds of optical interference filters were studied. We have formed samples consisting of discrete single layers with different porosities (e.g. Bragg reflectors) as well as samples with continuous variation of the refractive index (rugate filters). Combining these PS filters with standard photolithography steps, microoptical devices such as spectral sensitive photodiodes can be realized.