bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Determination of Mechanical Parameters and Residual Stresses for Thin Films Using Micro-Cantilever Beams
Authors: Hong S. , Weihs T. P. , Bravman J. C. , Nix W. D. 
Published: March 2011

AbstractA method for determining mechanical parameters and residual stresses for thin films is described. Multi-layer cantilever beams (LPCVD SiNx/thermal SiO2) are fabricated utilizing standard IC processing technologies and micromachining of silicon. The elastic response of the beams to imposed deflections is then measured using a Nanoindenter, a sub-micron hardness testing machine. The elastic constants of the nitride films are calculated from the force vs. deflection slope and known elastic constants of the thermal SiO2 and silicon. By measuring the curvature of the multi-layer cantilever beams with a scanning electron microscope after successive etching of the LPCVD nitride films, average and differential stresses in the films were calculated.
A Kinetic Model for Metalorganic Chemical Vapor Deposition of GaAs from Trimethylgallium and Arsine
Authors: Mountziaris Triantafillos J. , Jensen Klavs F. 
Published: March 2011

ABSTRACTA kinetic model for metalorganic chemical vapor deposition (MOCVD) of GaAs from trimethylgallium and arsine is presented. The proposed mechanism includes 15 gas-phase species, 17 gas-phase reactions, 9 surface species and 29 surface reactions. The surface reactions take into account different crystallographic orientations of the GaAs substrate. Sensitivity analysis and existing experimental observations have been used to develop the reduced mechanism from the large number of reactions that might in principle occur. Rate constants are estimated by using thermochemical methods and reported experimental data. The kinetic mechanism is combined with a two-dimensional transport model of a hot-wall tubular reactor used in experimental studies. Model predictions of gas-phase composition and GaAs growth rates show good agreement with published experimental studies. In addition, the model predicts reported trends in carbon incorporation.
Adsorption and Decomposition of Trimethylarsenic on GaAs(100)
Authors: Creighton J. R. 
Published: March 2011

ABSTRACTAlkylated arsenic compounds have shown some promise as alternatives to arsine as the group-V source gas for GaAs MOCVD. However, little is known about the fundamental chemical interactions of these compounds with the GaAs surface. We have investigated the adsorption and reactivity of trimethylarsenic (TMAs) on GaAs(100) using temperature programmed desorption (TPD), Auger electron spectroscopy, and LEED. For the exposures and temperatures studied, TMAs did not pyrolytically decompose on the GaAs(100). TPD results indicate that TMAs chemisorbs, apparently non-dissociatively, and desorbs ≅330 K. Multilayers of TMAs desorb ≅140–160 K. Exposure of adsorbed TMAs to 70 eV electrons results in irreversible decomposition of the molecule. After electron irradiation, TPD shows that methyl radicals desorb at 660 K, which corresponds to a desorption activation energy of ≅40 kcal/mol. At higher temperatures, As2, H2, C2H2, and a smaller amount of methyl radicals desorb, and a small coverage of carbon remains on the surface.
Catalytic Oxidation of Silicon Nitride thin films Using Potassium*
Authors: Rogers J. W. , Blair D. S. , Peden C. H. F. 
Published: March 2011

ABSTRACTThin silicon nitride films on a Si(100) substrate have been oxidized using potassium in a low thermal budget process. The presence of potassium on the SisN4 surface greatly lowers the temperature-time requirements for oxidation as compared with direct thermal oxidation.
Gas-Surface Reaction Studies Relevant to SiC Chemical Vapor Deposition
Authors: Stinespring C. D. , Freedman A. , Wormhoudt J. C. 
Published: March 2011

ABSTRACTReactions of C2H4, C3H8, and CH4 on Si(111) and C2H4 on Si(100) have been investigated for surface temperatures in the range of 1062 K to 1495 K. These studies used x-ray photoelectron spectroscopy to identify the reaction products, characterize the solid state transport process, determine the nucleation mechanism and growth kinetics, and assess orienta-tion effects. The results are used to provide insight into the mechanisms of SiC CVD processes.
Chemistry of Nitrogen-Silane Plasmas
Authors: Smith Donald L. , Alimonda Andrew S. , Preissig Frederick J. Von 
Published: March 2011

ABSTRACTThe N2-SiH4 rf glow-discharge plasma has been analyzed by line-of-sight mass spectrometry of species impinging on the deposition electrode, including N atoms. Properties of SixNyHz films deposited from this plasma have been examined. At high rf power and low SiH4/N2, almost all of the SiH4 is consumed by reaction with N atoms at the film surface and becomes incorporated into the film. No Si-N precursor species are seen in the gas phase. This is in contrast to the NH3-SiH4 plasma, where the Si(NH2)3 radical is the key precursor. If power is insufficient or SiH4 flow is excessive, Si2Hm species are generated in the plasma. Under optimized conditions, films slightly N-rich with no Si-H bonding and only 7% H (as N-H) can be deposited at high rate. The film tensile stress of the NH3 process is absent in the N2 process due to the lesser amount of condensation that takes place during deposition. However, trench coverage is much better in the NH3 process.
A Comparison Between Energetics of Decomposition and Photo-Deposition of Pd and Pt from Pd(C5 H5 )(C3 H5) and Pt(C5H5)(C3 H5)
Authors: Emrich Karl-Heinz , Stauf G. T. , Hirschwald W. , Barfuss S. , Dowben P. A. , Birge R. R. , Boag N. M. 
Published: March 2011

ABSTRACTThe energetics of decomposition of a variety of organometallic compounds have been determined from photoionization mass spectroscopy and electron impact mass spectroscopy. In particular, Pd(C5H5)(C3H5) and Pt(C5H5)(C3H5) have been studied in this fashion, and the information used to make patterned Pd/Ni/Si heterostructures by laser induced photolysis of the palladium compound and nickelocene in vacuum (MOCVD). Contamination in the thin films was determined by Auger electron spectroscopy, and compared with that found by other researchers for photo-deposition of Pt from the cyclopentadiene allyl [1].Thermodynamic data is used to explain differing contamination levels in the Pd and the Pt coatings.
Alloy Thin Films from Discrete Metallaborane Clusters
Authors: Fehlner T. P. , Amini M. M. , Zeller M. V. , Stickle W. F. , PRINGLE O. A. , Long G. J. , Fehlner F. P. 
Published: March 2011

ABSTRACTThe ferraborane HFe4 (CO)12 BH2 sublimes at 50 °C and decomposes by loss of H2 and CO on various substrate surfaces at 160–180 °C to yield films having metallic appearances with typical thicknesses of 4000Å. These films are amorphous by X-ray, conduct electricity and adhere well to glass, metal and silicon substrates. The composition was determined by ESCA and Auger spectroscopies. The films exhibit highly uniform composition and the Fe/B ratio is 4 showing that film stoichiometry is defined by the cluster core. The ESCA chemical shifts show the presence of boride and metallic iron. At present the bulk film contains a high level of oxygen in the form of iron and boron oxides. No ax-iron is present by X-ray or Mössbauer spectroscopies. Some carbon and hydrogen (SIMS) are present. Mössbauer spectra show the presence of magnetic iron similar to that exhibited by authentic Fe80 B20 samples but the films also contain substantial paramagnetic iron.
Dynamics of the KrF* Laser Multiphoton Dissociation of a Series of Arene Chromium Tricarbonyls
Authors: Tyndall George W. , Jackson Robert L. 
Published: March 2011

ABSTRACTThe KrF* (248 nim) laser multiphoton dissociation (MPD) of a series of (arene)chromium tricarbonyls has been investigated in the gas-phase using emission spectroscopy to detect the excited state photoproducts. In the MPD of all compounds studied, chromium atoms are formed in a variety of electronically excited states via a two-channel dissociation mechanism. The predominant pathway for formation of the ground electronic state and the lowest excited states is by a sequential absorption/fragmentation process, where the product of the one-photon dissociation of the parent molecule absorbs an additional photon and dissociates to Cr(I). The higher energy Cr(I) states are formed exclusively by a direct dissociation process, where the parent absorbs multiple photons prior to dissociation. The distribution of excited chromium atoms formed in the direct channel is statistical for all compounds studied and is independent of the nature of the arene ligand. In contrast, the distribution of Cr(I) states formed via the sequential dissociation channel is strongly dependent on the vibrational density of states in the arene ligand.
Laser CVD of A-Si:H: Film Properties and Mechanism
Authors: Hesch K. , Hess P. , Oetzmann H. , Schmidt C. 
Published: March 2011

ABSTRACTFilms of a- Si: Hwere deposited from Sill4 in a parallel configuration employing acw CO2 laser. Infrared spectra, photoconductivities and dark conductivities of the films were studied as a function of surface temperature between 250°C and400° C. The results are compared with data obtained from deposition experiments using Si2H6 and an ArF laser. Implications for the mechanism of LICVD are discussed.
Proximity Effect in the Low Pressure Chemical Vapor Deposition of Tungsten.
Authors: Lifshitz N. 
Published: March 2011

ABSTRACTThe self-limiting effect during Low Pressure Chemical Vapor Deposition of tungsten is manifested by a sudden interruption of the reduction of tungsten hexafluoride WF6 by silicon, so that only very thin (self-limited) films of silicon-reduced tungsten can be grown. It has been shown that the self-limiting effect is caused by formation of the non-volatile subfluoride WF4. The temperature dependence of the self-limiting thickness of the tungsten films grown in a hot-wall reactor exhibits a characteristic maximum at temperatures near 350°C, which indicates that at this temperature the rate of formation of WF4 is lower than at temperatures above and below. In the present paper we attempt to explain this peculiar dependence. We suggest a mechanism responsible for formation of the blocking agent WF4. We demonstrate that the presence of a hot tungsten surface is essential for the strong self-limiting effect. This leads us to the discussion of the proper selection of the reactor type (hot-wall vs. cold-wall) for different process requirements.
Assessment of Organotellurium Compounds for Use as Movpe Precursors
Authors: Hails J. E. , Irvine S. J. C. , Mullin J. B. , Shenai-Khatkhate D. V. , Cole-Hamilton D. 
Published: March 2011

ABSTRACTIn order to reduce the growth temperature of (Hg,Cd)Te by MOVPE below 350–400°C, alternative organometallic precursors will be required which either decompose at a lower temperature than existing precursors or which absorb strongly at a suitable wavelength in the ultraviolet. The features required for a programme of assessment of organometallics are discussed. UV absorption spectra for dimethyltelluride, dimethylditelluride, diethyltelluride, di-iso-propyltelluride and diallyltelluride are presented and their usefulness as photolytic MOVPE precursors discussed.
Gas Phase Interactions between Triethylindium and Trimethylgallium
Authors: Agnello P. D. , Ghandhi S. K. 
Published: March 2011

ABSTRACTA study of the room temperature gas-phase interactions between gallium and indium alkyls was undertaken using a mass spectrometer sampling system, mounted on a low pressure organometallic vapor phase epitaxial reactor. Mixtures of triethylindium with triethylgallium or trimethylgallium were investigated. Both combinations formed addition compounds; moreover, the triethylindium-trimethylgallium mixture underwent alkyl exchange. Both admixtures showed reduced reactivity towards arsine. A structure for the addition compound is proposed.
A New Look At Amorphous Vs Microcrystalline Structure
Authors: Spaepen Frans 
Published: March 2011

ABSTRACTHistorically, non-periodic models have usually found preference over microcrystalline ones for describing the structure of amorphous materials. Nevertheless, truly microcrystalline materials do exist, and the characteristic, monotonically decreasing isothermal calorimetric signal associated with the growth of the grains, can sometimes be used to identify them unambiguously. An example of the identification of the micro-quasicrystalline structure of some sputtered aluminum-transition metal alloys is discussed.
Mechanism of Achieving Nanocrystalline AIRu By Ball Milling
Authors: Hellstern E. , Fecht H. J. , Garland C. , Johnson W. L. , Keck W. M. 
Published: March 2011

ABSTRACTWe investigated through X- ray diffraction and transmission electron microscopy the crystal refinement of the intermetallic compound AIRu by high- energy ball milling. The deformation process causes a decrease of crystal size to 5–7 rum and an increase of atomic level strain. This deformation is localized in shear bands with a thickness of 0.5 to 1 micron. Within these bands the crystal lattice breaks into small grains with a typical size of 8–14 rum. Further deformation leads to a final nanocrystalline structure with randomly oriented crystallite grains separated by high- angle grain boundaries.
Preparation and Structure of Cu-W Multilayers
Authors: Unruh K. M. , Patterson B. M. , Shah S. I. , Jones G. A. , Kim Y.-W. , Greene J. E. 
Published: March 2011

ABSTRACTSputtered multilayer samples of W and Cu have been prepared on a variety of substrates with nominal individual layer thicknesses ranging from about 5 to about 100 A. High angle X-Ray Diffraction (XRD) data have been obtained at room temperature on all of these samples. In addition, selected samples have been studied by Transmission Electron Microscopy (TEM) and by low and high angle XRD from room temperature to above the melting point of bulk Cu. XRD and TEM data indicate that the as-deposited multilayer samples are comprised of well-defined individual layers due, in part, to the very small mutual solubility of W and Cu. At high temperatures the existence of low angle scattering peaks as well as satellites about Bragg peaks indicates that the layered structure is not lost. As a result, the W-Cu multilayer system seems to be an interesting candidate for the study of the melting behavior of thin Cu layers.
Physical-Chemical Properties of TiO2 Membranes Controlled By Sol-Gel Processing
Authors: Xu Qunyin , Anderson Marc A. 
Published: March 2011

ABSTRACTParticulate TiO2 membranes have been prepared by sol-gel techniques from alkoxide precursors. The degree of aggregation, which is controlled by physical chemical processes during sol preparation influences the gelling volume and gel structure. While three types of gel structures have been proposed, the porosity of the final membrane seems to be little affected by these hydrogel structures. Firing temperature is a much more critical parameter. It is concluded that the primary particle size determines the final membrane porosity in this TiO2 system.
Infrared Properties of Thin Pt/Al2O3 Granular Metal-Insulator Composite Films
Authors: MacMillan M. F. , Devaty R. P. , Mantese J. V. 
Published: March 2011

ABSTRACTThe reflection of mid- and near-infrared radiation (400-15000 cm−1 by thin Pt/Al2O3 cermet films was measured using a Fourier transform spectrometer. The data were compared with predictions of three models for the effective optical constants of heterogeneous materials: Maxwell-Garnett, Bruggeman, and a simplified version of a probabilistic growth model due to Sheng. Sheng's model provides the best description of the data over the complete range of metallic volume fraction. This result is expected based on the most likely topology of the films and is in agreement with other work on similar systems at higher frequencies.
Transmission Electron Microscope Observation of Dislocations in Ordered Intermetallic Alloys and the Flow Stress Anomaly
Authors: Veyssière Patrick 
Published: March 2011

ABSTRACTIt is only within the last five years that, with the increasing interest of several specialized groups, the amount of accurate TEM information on dislocations in ordered alloys, and in particular in theL12structure, has become significant. Our knowledge on superdislocation cores related todeformation under various temperature and deformation modes, is now sufficiently documented in order to be critically reviewed and this is the object of the present contribution.
A Tem Study of the Relationship Between Dislocation Structure and the Anomalous Temperature Dependence of the Flow Stress in Ordered Ni3 (Al,1%Ta).
Authors: Mills M. J. , Baluc N. , Karnthaler H. P. 
Published: March 2011

ABSTRACTThe anomalous increase in the yield strength of single crystals of Ni3AI(1%Ta) as a function of temperature has been correlated with the post-deformation substructure using weak beam TEM techniques. At low temperatures (77K), there is evidence for abundant cross-slip between (111) and (111). With increasing temperature, this conventional cross-slip process is gradually replaced by the formation of KW locks--straight screw segments which have crossslipped and completely dissociated on (010). This change in the mode of cross slip corresponds with the onset of the yield strength anomaly. At still higher temperatures (544K and 715K), the KW locks become mobile and bow out on (010). The density of dislocations on the cube plane also increases sharply at higher temperatures, even though deformation occurs principally by glide on the primary (111) based on slip trace analysis. These observations are inconsistent with the widely accepted cross slip pinning model and suggest that deformation occurs primarily by the motion of the non-screw components. A dislocation model is introduced which attempts to account for the observed dislocation configurations while remaining consistent with the yield strength and work hardening behavior of these alloys.
High Temperature Creep Behavior of Single Crystal Gammpraime and Gamm Laloys
Authors: Nathal M. V. , Diaz J. O. , Miner R. V. 
Published: March 2011

ABSTRACTThe creep behavior of single crystals of γ′ and γ alloys were investigated and compared to the response of two phase superalloys tested previously. High temperature deformation in the γ alloys was characteristic of a climb controlled mechanism, whereas the γ′ based materials exhibited glide controlled creep behavior. The superalloys were much more creep resistant than their constituent phases, which indicates the importance of the γ-γ′ interface as a barrier for dislocation motion during creep.
Microstructure and Deformation of Rapidly Solidified TiAl Alloys
Authors: Huang Shyh-Chin , Hall Ernest L. 
Published: March 2011

ABSTRACTBinary TiAl alloys containing 45–60 at.% Al were studied in detail in order to understand the fundamental deformation behavior and to establish a guideline for advanced alloy design. Because the formation of this compound involves a peritectic reaction, all alloys were processed by the melt spinning technique to minimize segregation. Microstructural and mechanical characterizations were carried out on both the as-solidified and consolidated materials. The results are presented to address the issues of (1) the equilibrium phase relationship, (2) the rapid solidification microstructure, (3) the room temperature deformation behavior, (4) the brittle/ductile transition, (5) the temperature dependence of yield stress, and (6) the implication on alloying effects. Several examples of ternary alloys are given.
Structures and Properties of TiAl-Base Alloys Containing Mn
Authors: Tsujimoto T. , Hashimoto K. 
Published: March 2011

ABSTRACTStructures and mechanical properties of TiAl-base alloys have been studied, in which Zr, Nb, V or Mn is added as the third element and the Al content is changed. Behavior of the third element in the TiAl-base alloys and effects of various factors on ductility have been discussed. It has been concluded that the Ti-48.4 at% Al-1.0 at% Mn alloy is the optimum composition for obtaining good room temperature ductility.
Powder Processing of High Temperature Aluminides
Authors: German R. M. , Bose A. , Stoloff N. S. 
Published: March 2011

ABSTRACTThis paper reviews the several powder processing techniques that have been applied to the fabrication of both monolithic aluminides and their composites. Attention is given to the active research at Rensselaer on reactive sintering and reactive hot isostatic pressing of elemental powders, hot pressing of prealloyed powders, and molding of powder-fiber-binder slurries. The application of one or more of these techniques to the following monolithic intermetallics is described: NiAl, Ni3Al, TiAl, NbAl3, Ta2Al, and TaAl3. Progress has occurred in fabrication of dense compacts, including some composites, from these aluminides.
Microstructures and Mechanical Behavior of Two-Phase Niobium Silicide-Niobium Alloys
Authors: Mendiratta M. G. , Dimiduk D. M. 
Published: March 2011

ABSTRACTIn the Nb-Si system, it is possible to produce in-situ composites consisting of a brittle Nb5Si3 intermetallic matrix and ductile Nb particles. The two phases are thermochemically stable up to ∼ 1500∼C and are amenable to wide microstructural variations including morphology, volume fraction, and the size of the individual microconstituents. This paper presents microstructures and phase transformations in these composites as a function of composition and heat treatments and bend properties from room-temperature to 1400°C.
The Location of Tantalum Atoms in Ni3Al
Authors: Lin Hui , Pope David P. 
Published: March 2011

ABSTRACTAn X-ray powder diffraction method was used to determine the location of tantalum atoms in Ni3Al. A series of Ni3 (Al,Ta) alloys were produced with tantalum content ranging from 0.1 to 3.0 at%. Fine powders with average particle sizes less than 80 pm were made from melt-spun ribbons by a grinding process. The values of the superlattice peak intensities normalized to the intensity of the (200) fundamental peak agreed with the calculated values assuming that tantalum atoms substitute on aluminum sites, not on nickel sites. Thus it is concluded from our experiments that tantalum atoms substitute for aluminum in Ni3Al, except for Ta contents around 0.2 at% where the data can not be interpreted in terms of a simple substitution scheme.
Compositional Effects on Processing and Properties of Nickel Aluminides
Authors: Sikka Vinod K. 
Published: March 2011

ABSTRACTCompositional effects on hot and cold workability of ductile-ordered nickel aluminides are described. Compositional effects studied include variations of chromium, aluminum, iron, and zirconium. The hot and cold workability of various nickel-aluminide alloys was ranked with respect to workability of stainless steel. The nickel-aluminide alloy containing chromium and low zirconium (IC-218LZr) had the best combination of hot and cold workability. This alloy also offered a good combination of strength and ductility values over a range of test temperatures.
Extended Solubility and Stability in Vapor Quenched Ni3al-X Intermetallics.
Authors: Wang Rong 
Published: March 2011

ABSTRACTA series of fine-grain and amorphous Ni3Al-X alloys, where X is a solute of 1 to 45 at.% Hf, C or Hf+C in continuously graded compositions, was formed simultaneously into a 0.2 mm-thick disk by high-rate sputter co-deposition. The as-deposited Ni3Al-X alloys exhibited a disordered Ll2 structure and extended solid solubility limits beyond which amorphous phases were formed. Heat-treatment of the alloys at 900°C resulted in fine grain size of 0.5 to 1.5 μm. Ultra-fine dispersoids less than 500 Å in size were observed and they seemed resistant to coarsening.