bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical Vapor Deposition of Al Films From Dimethylethylamine Alane on GaAs(100)2×4 Surfaces
Authors: Karpov I. , Campbell J. , Gladfelter W. , Franciosi A. 
Published: April 2011

AbstractChemical vapor deposition (CVD) of Al from dimethylethylamnine alane on atomically clean GaAs(100)2×4 surfaces has been investigated using an ultra-high-vacuum CVD reactor. Film composition, microstructure and growth rate were examined for deposition temperatures in the 100-500°C range. The results indicate reduced impurity incorporation at the lower deposition tenmperatures, and growth rates that are relatively temperatureindependent in the low-pressure regime examined (10−4to 10−5Torr). At temperatures ≥400°C the microstructure of films deposited by CVD and evaporation is remarkably similar, but at the lower deposition temperatures (∼150°C) the specific chemistry of the CVD process affects the film texture and preferential orientation.
Low Temperature Deposition of Tacn Films Using Pentakis(Diethylamido)Tantalum
Authors: Jun Gyu-Chang , Cho Sung-Lae , Kim Ki-Bum , Shin Hyun-Koock , Kim Do-Heyoung 
Published: April 2011

AbstractTaCN films were deposited at low temperature (≤400 °C) by metallorganic chemical vapor deposition (MOCVD) using pentakis(diethylamido)tantalum (PDEAT) as a precursor. The activation energy of the surface reaction is about 0.79 eV and the maximum deposition rate is about 100 Å/min at 350 °C. The resistivity of the as-deposited film decreases as the deposition temperature increases and the minimum value of resistivity obtained is 6000 μΩ-cm for the sample deposited at 400 °C. Major chemical elements in the films were detected as Ta, C, and N with some amounts of O by Auger electron spectroscopy (AES). By x-ray photoelectron spectroscopy (XPS), it is identified that the most of carbon in the films was bonded to Ta. The microstructural investigation using high resolution transmission electron microscopy reveals a nanocrystalline phase with an average grain size of about 30 Å. Preliminary investigation of the diffusion barrier property for copper showed that the 300 Å of TaCN diffusion barrier was failed after annealing at 500°C for 1 hr.
Ptfe Nanoemulsions as Spin-On, Low Dielectric Constant Materials For Ulsi Applications
Authors: Rosenmayer Tom , Wu Huey 
Published: April 2011

AbstractULSI Interconnects require insulative materials with as low a dielectric constant as possible in order to minimize crosstalk and parasitic capacitance. Transmission line simulations indicate that crosstalk in parallel interconnect lines can be dramatically reduced by lowering the dielectric constant of the insulation from 4 to 2. Polytetrafluoroethylene (PTFE) has a desirably low dielectric constant (2.05), but has previously been difficult to deposit in thin films suitable for integrated circuit applications. PTFE has other desirable properties, including temperature resistance in excess of 400 C and outstanding chemical resistance.A novel liquid material has been developed which permits the spin coat deposition of full density PTFE films from 0.2 to 1.0 microns thick. The deposition liquid is a solvent-free, stable PTFE nanoemulsion consisting of fully cured < 0.05 micron particles, surfactant, and water. The nanoemulsion is an equilibrium phase which is thermodynamically stable, optically clear, and has low viscosity. These properties are achieved because of the unusually small particle size of the nanoemulsion. The films are uniform in thickness with a standard deviation of < 2% and edge-to-center variation of < 5%. The films have a weight loss rate of less than 0.008%/min at 425 ° C. Good adhesion to Al, Si3N4, Si, and SiO2 is obtained when the films are evaluated per ASTM D3359-93. Several reseachers have reported methods by which various materials may be deposited onto PTFE with acceptable results.
Synthesis of Periodic Mesoporous Silica Thin Films
Authors: Anderson M. T. , Martin J. E. , Odinek J. G. , Newcomer P. 
Published: April 2011

AbstractWe have synthesized periodic mesoporous silica thin films (PMSTF) from homogeneous solutions. To synthesize the films a thin layer of a pH = 7 micellar coating solution that contains TMOS is dip- or spin-coated onto silicon wafers, borosilicate glass, or quartz substrates. Ammonia gas is diffused into the solution and causes rapid hydrolysis and condensation of the TMOS and the formation of periodic mesoporous thin films within ∼10 seconds. The combination of homogeneous solutions and rapid product formation maximizes the concentration of desired product and provides a controlled, predictable microstructure. The films have been made continuous and crack-free by optimizing initial silica concentration and film thickness.
Designer Carbons Templated by Pillared Clays: Lithium Secondary Battery Anodes
Authors: Sandí G. , Carrado K. A. , Winans R. E. , Brenner J. R. , Zajac G. W. 
Published: April 2011

AbstractThis work describes the designed synthesis and physical characterization of carbons containing predictable microporosity. The approach is to pyrolyze aromatic hydrocarbons such as pyrene within a pillared clay. The pillared clay serves two functions. It performs as the inorganic template around which the designer carbon can be formed, and it acts as an acid catalyst to promote condensation of the aromatics similar to the Schöll reaction. These precursors then undergo thermal polymerization and carbonization at 700 °C. Removal of the pillared clay template is accomplished by standard acid demineralization techniques, leaving behind carbons with 15 to 50 Å holes.
Bicontinuous Cubic Phase as a Matrix for the Synthesis of Semiconductor Nanocrystallites
Authors: Yang Jianping , Qadri Syed , Ratna Banahalli 
Published: April 2011

AbstractBicontinuous cubic phase of lipid has been utilized for the first time as a matrix to synthesize II–VI (CdS) and IV–VI (PbS) semiconductor nanocrystallites. The nanoparticles were isolated from the lipid matrix and stabilized by capping with a thiol compound before purification. Two different sizes (2.3 nm and 3.0 nm) of CdS particles were prepared by varying the conditions of preparation. The size was determined by a combination of UV-vis absorption spectra and X-ray diffraction (XRD). The steep absorption edges of the two CdS samples indicate very narrow size distribution. XRD and transmission electron microscopic imaging of PbS nanocrystallites revealed that the size was 4.9 nm with nearly monodispersed size distribution.
Permeability and Structure of Resorcinol – Formaldehyde Gels
Authors: Scherer G. W. , Alviso C. , Pekala R. , Gross J. 
Published: April 2011

AbstractThe permeability (D) of resorcinol-formaldehyde (RF) gels was measured using a beam-bending technique. For gels made at various solids contents and with different catalyst contents, the permeabilities ranged over a factor of ∼50; the pore radii inferred from D varied from ∼3 to 30 nm. Pore radii obtained on RF aerogels using nitrogen desorption were severely affected by compression of the aerogel by capillary forces (resulting from the surface tension of liquid nitrogen). After correction for that effect, the desorption data were found to be in very good agreement with the pore sizes calculated from D.
Heterogeneous Microcomposite Materials Based on Porous Matrices and Liquid Crystals
Authors: Aliev F. M. , Sinha G. P. 
Published: April 2011

AbstractHeterogeneous microcomposite materials based on porous matrices with randomly oriented, interconnected pores (porous glasses with average pore sizes of 100 Å and 1000 Å) and parallel cylindrical pores (Anopore membranes with pore diameters of 200 Å and 2000 Å) impregnated with liquid crystals (LC) were investigated by dynamic light scattering and dielectric spectroscopy. The physical properties of confined LC are very different from that of the bulk. One of the new properties among others observed for LC confined in porous matrices is the slow relaxational process which does not exist in the bulk LC and a wide spectrum of relaxation times (10−8 – 10)s which were established in both dynamic light scattering and dielectric experiments. We found that for LC dispersed in porous matrices with randomly distributed interconnected pores, the contribution to physical properties and observed behavior from interfacial layers dominates and almost completely determines low frequency relaxational process.
Aluminas Rehydration and Dehydration
Authors: Fripiat J. J. 
Published: April 2011

AbstractIn this review paper, results on the A12O3-water interactions will be critically examined. The synthesis of alumina precursors rich in structural defects can be operated in an aqueous solution containing ligands with high affinity for A13+aqor by restricted hydrolysis of Al-alkoxides. Calcination of the gels yields transition aluminas containing four (IV), five (V) and six (VI) fold coordinated aluminum. The pore-size distribution, the Alvcontent and the degree of crystallinity are controlled by the degree of condensation of the oligomer species in the gel. In a dehydrated alumina two kinds of AlIVwith isotropic chemical shifts at ∼73 and 58 ppm, respectively, are present. The distorted AlIV(chemical shift at 58 ppm) and Alvare surface species. Upon water chemisorption the distorted AlIVline disappears while the Alvline is reinforced. As bulk rehydration progresses the Alvline intensity decreases. It is only partially restored upon recalcination. Thus, hydration-rehydration cycles cure the solid from its defects and increase crystallinity. The onset of rehydration is the chemisorption of water on the surface Lewis sites just as Lewis sites result from a thorough dehydration.
Selective Dissolution in Copper-Tin Alloys: Formation of Corrosion-Resistant Patina on Ancient Chinese Bronze Mirrors
Authors: Taube Michelle , Davenport Alison J. , King Alexander H. , Chase W. Thomas 
Published: April 2011

AbstractMany ancient Chinese bronze mirrors have survived with a patina that leaves the delicate relief surface decorations intact. The microstructure of these ancient mirrors is two-phase and consists of acicular α-phase (Cu-rich) regions encased in a δ-phase (Sn-rich) matrix. At the surface, there is evidence of selective dissolution of the α-phase; the α-phase regions are replaced pseudomorphically by a mineral product with the δ -phase remaining metallic. Electrochemical polarization has been used to drive the copper dealloying process in modern, cast bronze. Synchrotron x-ray diffraction was employed to compare the ancient samples with those that were prepared potentiostatically. Poorly crystallized tin oxide (SnO2) was found in the α - replacement products of both sample types. The corrosion-resistance of the potentiostatically-treated bronze samples was tested by atmospheric exposure. Comparison with exposed, untreated samples indicated that the treatment was protective.
Mineral Redox Buffers and The Stability of Organic Compounds Under Hydrothermal Conditions
Authors: Seewald J. S. 
Published: April 2011

AbstractOrganic compounds play an integral role in numerous geochemical process in subsurface environments. To evaluate factors that regulate the stability of ethane, ethene, propane, and propene in hydrothermal systems a series of experiments were conducted at 300 to 325°C and 350 bars. The experiments contained the mineral assemblages pyrite-pyrrhotite-magnetite, hematite-magnetite-pyrite, and hematite-magnetite to buffer fO2, aH2(aq) and aH2S(aq) at geologically reasonable values.Results of the experiments suggest that under appropriate physical and chemical conditions, metastable redox dependent thermodynamic equilibrium involving liquid water and inorganic iron-bearing mineral assemblages may regulate the relative abundance of short chain alkanes and their corresponding alkenes. In addition, alkenes represent an important intermediary in the conversion of n-alkanes to methane and oxidized species such as carbon dioxide, ketones alcohols, and organic acids.The rates of redox dependent organic reactions during the experiments were strongly influenced by the presence of sulfur. Under relatively oxidizing conditions greater catalytic activity due to the presence of dissolved sulfur species was observed. Fluid speciation calculations suggest that oxidized aquous sulfur compounds represent the catalytically active species.These results suggest that redox conditions and the presence or absence of dissolved sulfur species in natural sedimentary environments may strongly influence the stability of hydrocarbons. Accordingly, models used to predict the stability of oil and the formations of natural gas need to account for chemical processes that involve both organic and inorganic sedimentary components.
Large area Pulsed Laser Deposition of Aurivillius-Type Layered Perovskite Thin Films
Authors: Pignolet A. , Curran C. , Welke S. , Senz S. , Alexe M. , Hesse D. , Gösele U. 
Published: April 2011

AbstractThin films of Aurivillius-type layered perovskites of Bi4Ti3O12and SrBi2Ta2O9have been epitaxially deposited by pulsed laser deposition (PLD) on SrTiO3single crystal substrates. Bi4Ti3O12has been deposited as well on a CeO2JYSZ/Si(100) buffer layer, and on Pt-coated oxidized silicon for electrical measurements. Using a new technique for large area PLD, Bi4Ti3O12has also been deposited on a whole (100)-oriented 3”- Si wafer. The obtained films have a uniform thickness over a diameter greater than 50 mm, corresponding to an area of about 20 cm2. It is likely that homogeneous deposition on entire wafers of 3-inch in diameter will be accomplished in the near future. The composition, structure, and electrical properties of the films are presented.
Dependence of Composition and Microstructure of RuOx Films on Target Status and Substrate Temperature in Reactive Sputtering Deposition
Authors: Wang Q. , Yang K.-A. , Franciosi A. , Evans D. F. , Gladfelter W. L. 
Published: April 2011

AbstractRuthenium oxide films were deposited on Al2O3 (0001) and (1102) substrates using reactive sputtering under two different target surface conditions. Films grown when the surface of the target was metallic ruthenium (metallic-target) showed a Ru: O ratio of 1: 2.0±0.05 as determined by Rutherford backscattering spectrometry. At elevated deposition temperatures, these films aligned with the substrates as RuO2 (100) ║ A12O3 (0001) and RuO2 (101) ║ Al2O3(1102). Films deposited when the target surface was fully oxidized (oxidized-target) exhibited a Ru: O ratio of 1: 2.5±0.05 and displayed an oriented crystalline structure even at room temperature. The resistivity of the RuO2.5 films was 75 μΩ-cm and was independent of temperature between 5 and 300 K. Possible causes of this behavior are discussed.
Effect of Surface Morphology of NiCr-Bottom Electrode on Preparation of Ferroelectric PZT Thin Film Capacitor
Authors: Lee K.B. , Rhee B.R. , Cho S.K. 
Published: April 2011

AbstractWe have studied the optimum conditions of the deposition of NiCr-bottom electrode for preparing the ferroelectric PZT(50/50) thin film capacitor. The NiCr(80/20) layer of about 300nm in thickness was deposited on bare Si(111) wafer by rf magnetron sputtering. The surface morphology and crystallinity were investigated by using Atomic force microscope (AFM) and X-ray diffractormeter (XRD). It is found that the size and crystallinity of grains of NiCr or Ni-silicide depend mainly on the rf power. The PZT(50/50) thin films were prepared on NiCr/Si substates by spin-casting of PZT coating sol and then annealing at 520°C in air for crystallization. The undesirable Pb-silicate is found to be grown during post-annealing in case that substrates having NiCr layer deposited by high power above 80 W are used. We suggest that the formation of Pb-silicate is due to the thermal diffusion of Pb or PbO through crystalline NiCr-grain boundaries. The ferroelectric PZT thin films having the perovskite structure can be obtained by using the NiCr-bottom electrodes whose morphologies are in the amorphous-crystalline boundaries, in which the surface roughness and grain size of NiCr layer is minimum. The values of the dielectric constant, εn, were measured in the range 300˜500, the remanent polarization, Pr, in the range 10˜13 C/cm2 and the coercive field, Ec, around 160 kV/cm, depending on the deposition conditions of NiCr layers.
Step Coverage of Pb(ZrTi)O3 Thin Films Grown by Mocvd
Authors: Shimizu M. , Hyodo S. , Fujisawa H. , Niu H. , Shiosaki T. 
Published: April 2011

AbstractStep coverage of PZT grown by MOCVD was influenced by the growth temperature, the reaction pressure and the aspect ratio of the trench. PZT films grown on Si steps at growth temperatures ranging from 500 to 600°C and at reaction pressures ranging from 3 to 10Torr showed a step coverage of 52 to 86%. The step coverage of PZT grown at 600°C and at 5Torr – conditions which were suitable for the growth of perovskite phase – was 75%. The step coverage of Pt on Si and on SiO2 was 20% and 25%, respectively.
Study of Thin Film Ferroelectric Superlattices
Authors: Kim Y. , Erbil A. , Thomas E.W. , Kushwaha A. , Gerhardt R. 
Published: April 2011

AbstractThe study of ferroelectric thin films has evoked special interest owing to their numerous applications. In this study, epitaxial or highly oriented PbTiO3/PLT (Lead Titanate / La modified Lead Titanate) ferroelectric superlattice thin films were grown by the metalorganic chemical vapor deposition (MOCVD) technique. Compositional modulation by Secondary Ion Mass Spectroscopy (SIMS) established the nature of these films as desirable for high quality device applications. The thickness and the refractive index of each film was determined by using a prism coupler. The dielectric behavior of these films was studied as a function of frequency.
Structure, Composition and Properties of (Pb,La)TiO3 Thin Films by Rf Magnetron Sputtering
Authors: Murhy C.E. , Hata H. , Tsutsumi K. 
Published: April 2011

AbstractThin films of lanthanum-doped lead titanate for use in pyroelectric detectors were deposited on Si wafer system substrates by an RF magnetron sputtering method. Deposition was from a ceramic target with excess lead using Ar plus N2O sputter gases. The film structure, composition and electrical properties were examined as a function of substrate temperature during film deposition, Tsub, from 600°C to 750°C. Dense, featureless film cross-sections existed up to Tsub=625°C, while vertical columns, indicative of crystalline material, were present from Tsub=650°C upwards. At Tsub=600°C films were amorphous, but from Tsub=625°C upwards a highly crystalline perovskite phase was found. The tetragonality was very small, c/a˜1.006, indicating the existence of a pseudo-cubic structure. Compared to the idealized chemical formula, Pb1−xLaxTi1−x/4O3, films produced at Tsub<650°C or Tsub>700°C were Pb deficient, while only in the very narrow 650–700°C Tsub range was near-stoichiometry obtained, with a slight lack of Ti. The substrate temperature during deposition is apparently a critical factor in obtaining stoichiometric films. The La content with respect to Pb was 9.5% which would be expected to yield a reasonably tetragonal crystal structure in bulk material, however stress due to the substrate may account for this discrepancy. The relative permittivity, εr, showed a sharp transition from ˜50 at Tsub=600°C to 450–550 between 650°C and 750°C. This behaviour parallels both the microstructural and crystal lattice changes from amorphous to perovskite material. Even though on polycrystalline underlayers, pyroelectric activity, p, was measured on as-deposited films, the polarization being directed into the substrate and a peak of 1.2×10−4Cm−2K−1 appearing at Tsub=700°C. After DC thermal poling, at 100°C with 8V for 20min, p increased dramatically, with Tsub 700°C and 725°C films exhibiting p=2.0×10−4Cm−2K−1. The peak in the poled p value corresponded to the maximum found in the crystal tetragonality and agrees with increasing p as polarization increases from a cubic to tetragonal structure.
Dielectric and Ferroelectric Characterization of Sol-Gel Derived Ca-Doped PbTiO3 Thin Films
Authors: Teowee G. , McCarthy K.C. , Franke E.K. , Boulton J.M. , Alexander T.P. , Bukowski T.J. , Uhlmann D.R. 
Published: April 2011

AbstractA series of sol-gel derived CaTiO3- PbTiO3 thin films ( i.e. Pb1−xCaxTiO3 with x = 0 − 1) was prepared on platinized Si substrates and fired to temperatures ranging from 550C to 650C. Multiple spincoating was performed to obtain films up to 0.5 μm thick with an intermediate firing of 400C between coatings. After the final crystallization firing, top Pt electrodes were sputtered to form monolithic capacitors. These capacitors were subjected to dielectric and ferroelectric characterization using an impedance analyzer and Radiant Technology RT66A Ferroelectric Test System. XRD was used to study the phase development and phase assembly of the fired films. All compositions were single perovskite phase after firing to 600C. The effects of Ca content on the crystallization behavior and ferroelectric properties are discussed.
Mechanical Behavior and Constitutive Modeling During High Temperature Deformation of Al Laminated Metal Composites
Authors: Grishaber R. B. , Mishra R. S. , Mukherjee A. K. 
Published: April 2011

AbstractA constitutive model for deformation of a novel laminated metal composite (LMC) which is comprised of 21 alternating layers of Al 5182 alloy and Al 6090/SiC/25p metal matrix composite (MMC) has been proposed. The LMC as well as the constituent or neat structures have been deformed in uniaxial tension within a broad range of strain-rates (i.e. 10−5 to 100 s−1) and homologous temperatures (i.e. 0.8 ≥ 0.95 Tm). The results of these experiments have led to a thorough characterization of the mechanical behavior and a subsequent semiempirical constitutive rate equation for both the Al 5182 and Al 6090/SiC/25p when tested monolithically. These predictive relations have been coupled with a proposed model which takes into account the dynamic load sharing between the elastically stiffer and softer layers when loaded axially during isostrain deformation of the LMC. This model has led to the development of a constitutive relationship between flow stress and applied strain-rate for the laminated structure.
Examination of In-Service Coating Degradation in Gas Turbine Blades Using a Small Punch Testing Method
Authors: Kameda J. , Bloomer T. E. , Gold C. R. , Sugita Y. , Ito M. , Sakurai S. 
Published: April 2011

AbstractThis paper describes examination of in-service coating degradation in land based gasturbine blades by means of a small punch testing (SP) method and scanning Auger microprobe(SAM). SP tests on coated specimens with unpolished surfaces indicated large variations ofthe mechanical properties because of the surface roughness and curvature in gas turbine blades, SP tests on polished specimens better characterized the mechanical degradation of bladecoatings. The coated specimens greatly softened and the room temperature ductility of thecoatings and substrates tended to decrease with increasing operation time. The ductile-brittletransition temperature of the coatings shifted to higher temperatures during the bladeoperation. From SAM analyses on fracture surfaces of unused and used blades, it has beenshown that oxidation and sulfidation near the coating surface, which control the fractureproperties, result from high temperature environmental attack.