bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preferred Orientations for Sol-Gel Derived Plzt Thin Layers
Authors: Tani Toshihiko , Xu Zhengkui , Payne David A. 
Published: March 2011

AbstractPLZT thin layers were deposited onto various substrates by sol-gel methods, and crystallized under different conditions and substrate treatments. Relationships are given for the chemical characteristics of the substrate's surface and the preferred orientations which develop on heat treatment. A preferred (111) orientation always developed for perovskite crystallized on Pt layers which contained Ti on the surface. This was attributed to the formation of Pt3Ti and the role of heteroepitaxial nucleation and growth sites. In addition, a preferred (100) orientation was also obtained on unannealed Pt/Ti/SiO2/Si substrates which were free of Ti on the surface. This was attributed to self-textured growth with flat faces striving for minimum surface energy conditions. The results are discussed in terms of the importance of interfacial chemistry on the control of texture for crystallization of PLZT thin layers on coated substrates.
Solution Chemistry Optimization of Sol-Gel Processed Pzt Thin Films
Authors: Lockwood Steven J. , Schwartz R. W. , Tuitle B. A. , Thomas E. V. 
Published: March 2011

AbstractWe have optimized the ferroelectric properties and microstructural characteristics of sol-gel PZT thin films used in a CMOS-integrated, 256 bit ferroelectric non-volatile memory. The sol-gel process utilized in our work involved the reaction of Zr n-butoxide, Ti isopropoxide, and Pb (IV) acetate in a methanol/acetic acid solvent system. A 10-factor screening experiment identified solution concentration, acetic acid addition, and water volume as the solution chemistry factors having the most significant effects on the remanent polarization, coercive field, ferroelectric loop quality, and microstruntural quality. The optimal values for these factors were determined by runnig a 3-factor uniform shell design, modelling the responses, and testing the models at the predicted optimal conditions. The optimized solution chemistry generated 3-layer, 300-400 nm thick films on RuO2 coated silicon substrates with coercive fields of less than 25 kV/cm (a 40-50 % improvement over the original solution chemistry), a remanent polarization of 25-30 μC/cm, and a reduction in the pyrochlore phase content below observable levels.
Microstructural Characterization of Sol-Gel Derived Lead Titanate Deposited On Silica
Authors: Schwartz Joseph M. , Francis Lorraine Falter , Schmidt Lanny D. 
Published: March 2011

AbstractThe microstructural evolution of lead titanate prepared by a sol-gel method was examined using transmission electron microscopy (TEM) following treatments in air at progressively higher temperatures. TEM specimens were prepared by spin coating a film or dispersing particles onto specimen grids coated with SiO2 or SiO2 with a barrier layer. The effects of different barrier materials, thermal treatment conditions, and the addition of platinum particles were examined. Lead titanate formed crystalline perovskite at ∼550-600°C on all support materials examined. On SiO2 supports, the pyrochlore phase formed at lower temperatures and converted partially to perovskite at higher temperatures. Barrier layers of TiO2, A12O3 and polyimide prevented pyrochlore formation.
Formation of BaMgF4 Films on Pt/MgO, Si and GaAs Substrates
Authors: Aizawa Kouji , Ichiki Tatsuya , Ishiwara Hiroshi 
Published: March 2011

AbstractCrystalline quality of BaMgF4 films grown on Pt/MgO, Si, and GaAs substrates either by solid phase crystallization (SPC) or by molecular beam epitaxy (MBE) has been investigated. In the SPC method, the films are deposited typically at 300°C in amorphous state and subsequently crystallized at temperatures higher than 500°C. It has been found from X-ray diffraction analysis that (010)-oriented films are grown on the three substrates by the SPC method, while that (011)- and (120)-oriented films are grown on respective (100)- and (111)-oriented substrates of Si and GaAs, when the MBE method is used at substrate temperatures around 500°C. These results show that the spontaneous polarization which is generated along a-axis of a BaMgF4 crystal, is not parallel to the film surface, only when the films are grown on (111) substrates by MBE.
Epitaxial Growth of Pt(001) Thin Films on MgO(001) Under Oxidizing Conditions
Authors: Cui G. , Buskirk P. C. Van , Zhang J. , Beetz C. P. , Steinbeck J. , Wang Z. L. , Bentley J. 
Published: March 2011

AbstractEpitaxial Pt(001) thin films have been grown on MgO(001) substrates using dc magnetron sputtering with an Ar/O2 mixture at 700°C. The width (FWHM) of the rocking curve of the Pt(002) peak is between 0.16° and 0.20°, which is only 0.05° wider than that of the MgO (002) peak of the cleaved substrate. The film surface roughness is about 1 nm (rms) for a 240 nm thick Pt film. No grain structure could be observed using SEM. In contrast, the films deposited at 700 °C with pure Ar, have both Pt(111) and Pt(001) oriented growth, as shown by XRD Θ - 2 Θ scans, with the Pt(111) peak having the largest intensity. BaTiO3 epitaxial films have also been deposited on Pt(001)/MgO(001). The width (FWHM) of the rocking curve of the BaTiO3(200) peak is 0.4°. The surface morphology of the epitaxial BaTiO3(100) thin films on Pt(001)/MgO(001) is featureless. XRD pole figure measurements on Pt/BaTiO3/Pt trilayer shown a very good in-plane alignment of all layers. The epitaxial growth relationship was also confirmed by TEM electron diffraction and cross-section imaging. The Pt/BaTiO3/Pt epitaxial trilayer could serve as a prototype for ferroelectric capacitors and may be able to improve the electrical properties of the capacitors.
Examination of Titanium Oxides, Lead Oxides and Lead Titanates Using X-Ray Diffraction and Raman Spectroscopy
Authors: Madsen Lynnette D. , Weaver Louise 
Published: March 2011

AbstractSingle oxides (with titanium or lead) deposited as thin films by low pressure metalorganic chemical vapour deposition were investigated by x-ray diffraction and Raman spectroscopy. Examination of mixed oxides (titanates) and silicates were also carried out using these techniques. The crystallographic nature of these thin films were examined and comparisons made to their bulk counterparts. The deposition and anneal conditions 600 for producing cubic PbTiO3 films are discussed briefly.
Ferroeleciric Thin Films Intended for Electronic Device Applications
Authors: Patel A. , Logan E.A. , Nicklin R. , Hasdell N.B. , Whatmore R.W. , Uren M. 
Published: March 2011

AbstractThe need for integrated ferroelectrics as charge storage capacitors has increased dramatically not only for use in radiation hardened and commercial non-volatile memories, but also as possible high dielectric material suitable for capacitor applications. These properties combined with a thin film format, offer the capability of forming very compact capacitor structures suitable for MCM applications through Flip-Chip Bonding, or even integrated directly onto MMIC's. In this paper, the material PbZrxTi1-xO3, where x=l, 0.53, and 0.60 has been assessed. Thin films were produced using a sol-gel technique onto metallised thermally oxidised silicon. The effects on film microstructure and crystallinity with variation in the deposition process will be described. The best films were obtained by incorporating excess lead in the starting solutions, and also by the addition of acetylacetone which was used as a solution modifier. It will be demonstrated that fully perovskite films can be readily obtained at temperatures as low as 450°C. The films were normally 0.3-0.44μm thick with grain sizes of the order of 0.2μm. These films exhibited dielectric constants and loss in the range 170-800 and 1-3% respectively. Measurements upto 3MHz, indicated useful performance with low dispersion. The measured Pr and Ec were in the range 16-22μC/cm2, and 60-120kV/cm respectively.
Electrical Properties of Sol-Gel Pzt Thin Films for decoupling Capacitor Applications
Authors: Schwartz Robert W. , Dimos D. , Lockwood S. J. , Torres V. M. 
Published: March 2011

AbstractThe successful development of PZT thin films for decoupling capacitor devices places stringent requirements on the dielectric and leakage properties of the films. We have characterized these properties for PZT thin films with compositions near the morphotropic phase boundary prepared by a sol-gel process. Capacitors were fabricated from films with thicknesses varying from 0.4 to 1.2 µm. For zero applied bias, the dielectric constants of these films were in the range of 800 to 1200. The room temperature dielectric constant was observed to decrease by ∼ 25% with the application of a 5 V bias. We have also characterized the interrelationships between temperature, applied bias, and dielectric constant. The capacitors exhibited asymmetry in their leakage and breakdown characteristics with bias sign, as well as non-linear I-V behavior. Breakdown fields for undoped PZT 53/47 films were typically in the range of 750 kV/cm.We have also studied the effects of La and Nb donor doping on the leakage behavior of PZT 50/50 thin films. Doping with 2 to 5 mol % of either La or Nb resulted in a reduction in film leakage current by a factor of 103. Leakage currents of the highly doped materials were approximately 2 × 10−9 A/cm2 under an applied field of ∼ 65 kV/cm at a temperature of 125×C.
Characterization of Au-Mediated a-Si:H Crystallization by In Situ Electrical Measurements
Authors: Pasa A. A. , Achete C. A. , Losch W. , Bauer G. H. 
Published: March 2011

ABSTRACTThe Au-mediated crystallization of a-Si:H has been investigated by in situ electrical measurements and scanning electron microscopy. The a-Si:H structure was prepared by evaporation of Au thin films of different thicknesses (50 - 600 Å) onto intrinsic glow discharge deposited a-Si:H layers (≈ 5000 Å). A rapid increase in the electrical resistance was associated to the nucleation and growth of Si crystals inside the Au film. The growth process promotes the accumulation of Au at the Si grain boundaries forming a metallic network. This network controls the electric resistance at the end of the crystallization reaction. The kinetics of transformation has been studied by isothermal treatments over the 140 - 180 °C temperature range. An activation energy of 2.1 eV was measured. An analysis of resistance data obtained by constant heating rate treatments suggest the rupture of the network interconnections at T ≥ 170 °C. SEM pictures showing the formation of Au clusters confirmed this suggestion.
Morphological Transformations in the Crystallization of Tese-Halide Thin Films
Authors: Blatter A. , Ortiz C. , Adam J. L. 
Published: March 2011

ABSTRACTAmorphous Te3Se4 X (X = Br,I) thin films were prepared by RF sputter deposition where the halide is used to stabilize the amorphous structure. Crystallization in the films was induced by heating with pulsed laser irradiation, with an electron beam, and in a furnace. Crystallization was achieved when the halide was depleted which became more difficult the higher its mass and concentration. As a consequence, crystallization was highly anisotropic and confined to a thin surface layer with a lateral size to thickness ratio of up to 104. We observed various stages of the process. At low temperature, a spherulitic-type growth produced a low-dimensional branching morphology by non diffusive processes such as rotation. Increasing temperature favored the formation of higher dimensions with patterns typical for aggregation processes. At the highest temperatures material flow enabled the formation of three-dimensional structures. In case of the films with Iodine, facetted single crystals grew out of the surface to sizes many times larger than the original film thickness.
Dynamics of Thin Film NiTi Cantilevers on Si
Authors: Jardine A.Peter , Mercado Peter G. 
Published: March 2011

ABSTRACTAlthough the thermo-mechanical properties of NiTi are well known for bulk material, its deposition and utilization as a thin film are still in their earliest stages of research. The deposition of thin-films of Shape Memory Effect NiTi onto Si(100) wafers offers several advantages over bulk NiTi, including fast response times and comparatively large transformation forces. This has made it a promising candidate material as micro-actuators for Micro-Electro-Mechanical (MEMS) systems as well as for strain measurements. The cycling time for actuation was measured for a 20 μm free standing NiTi thin film cantilever. It was demonstrated that cycling frequencies of up to 50 Hz are achievable.
Phase Equilibria under Irradiation
Authors: Bellonw P. , Soisson F. , Grandjean Y. , Martin G. 
Published: March 2011

ABSTRACTA solid under irradiation is a far-from equilibrium system, and therefore phase equilibria in such a system cannot be assessed from equilibrium thermodynamics. Starting from a kinetic description which incorporates the various processes responsible for atomic diffusion (e.g. thermally activated jumps, replacement sequences or displacement cascades), the various possible steady-states can be identified analytically or numerically, as well as their kinetic evolution on varying the control parameters of the system (e.g. temperature, average composition, irradiation flux, cascade density …). Furthermore, from stochastic versions of the kinetic model, potentials governing the stationary probability distribution of states can be derived, allowing to build dynamical equilibrium phase diagrams.Illustrating the above approach on the A2-B2 order-disorder transition, we have identified irradiation-induced two-phase state, cascade size and density effects on phase stability. By incorporating point defects, such description is well suited to study irradiation-induced segregation at sinks in concentrated alloys.
Formation of Sic Films on Silicon Field Emitters
Authors: Liu Jiang , Son U. T. , Stepanova A. N. , Christensen K. N. , Wojak G. W. , Givargizov E. I. , Bachmann K. J. , Hren John J. 
Published: March 2011

ABSTRACTThin films of silicon carbide have been formed on silicon field emitters by chemical reaction with ethylene (C2H4) at temperatures of 850 to 950°C using ethylene gas pressures up to 5×10-3 Torr. By controlling the reaction time and temperature, we have made SiC coatings of from ∼20 A thickness to complete transformation of tips to SiC (1-2 μm). The electron diffraction pattern of the SiC layers show the expected 20% lattice mismatch with silicon and, for those emitters completely transformed, a polycrystalline 3C-SiC polytype was identified. The small radius of curvature was maintained for both the coated and completely transformed tips, although some defects and surface roughness was introduced during the treatments.
Ion Irradiated Amorphous Silicon: A Model Approach to Dynamics of Defect Creation and Annihilation
Authors: Shin Jung H. , Atwater Harry A. 
Published: March 2011

ABSTRACTThe dynamics of defect annihilation and creation in amorphous silicon (a-Si) are measured in detail using defect-related changes in the electrical conductivity of a-Si A model is proposed which for the first time can track the complete time evolution of defect population across the activation energy spectrum with explicit dependence on irradiation and annealing parameters. The model is based upon experimental activation energy spectrum, bimolecular recombination kinetics, and on the notion of a maximum density of defect states beyond which no additional defects can be supported. The new model predicts transient dynamics in defect population and describes structure of the defect population in detail. Its predictions are in good qualitative agreement, and in reasonable quantitative agreement with experimental data.
Activation Energy for the C49-TO-C54 Phase Transition of Polycrystalline TiSi2 Films with under 30nm Thickness
Authors: Matsubara Y. , Noguchi K. , Okumura K. 
Published: March 2011

ABSTRACTThe C49–to–C54 transition in TiSi2 was investigated by resistance measurement and x-ray diffraction technique. The resistance measurement showed that the C49–to–C54 transition has an activation energy strongly dependent on the titanium thickness. The energy increased with the thinning of the TiSi2, from 4.6±0.3 eV for TiSi2 formed with 50nm titanium, to 10.5±0.3 eV formed with 20nm titanium. Furthermore, x-ray diffraction result showed that (004)-oriented phase in C54 TiSi2 is responsible for the increase in activation energy. This orientation dependence of the activation energy probably originates from anisotropy in C54 crystal growth during the transition.
Morphology and Phase Metastability in the Al/Cu Thin Film Reaction.
Authors: McCarty E. D. , Hackney S. A. 
Published: March 2011

ABSTRACTThe initial stages of the reaction between thin Al grains with an average diameter of 2 × 10−5mand sputter deposited, nanocrystalline Cu films has been studied in plan view using in situ transmission electron microscopy. At high reaction rates, the phase transformation in the Al grain resulting from the interdiffusion process is found to exhibit metastable growth morphologies characterized by negative curvature at the growth interface. The crystal structure of the initial phase formed in the Al grain under relatively high reaction rates is a metastable, orthorhombic distortion of the equilibrium body centered tetragonal θ phase. The distortion is found to vary with Al grain surface orientation. The degree of metastability can be experimentally correlated with the kinetics of the interdiffusion process as controlled by diffusion barrier thickness.
Evolution of Cubic FeSi2in Si upon Thermal Annealing
Authors: Lin X.X. , Desimoni J. , Bemas H. , Liliental-Weber Z. , Washburn J. 
Published: March 2011

ABSTRACTCubic FeSi2precipitates were produced in Si (001) wafers by Fe implantation at room temperature, followed by ion beam-induced crystallization at 320°C, and their stability upon thermal annealing was examined by transmission electron microscopy. We found that the cubic phase remains relatively stable for a 650°C anneal, but the precipitates tend to change from an aligned to a twinned orientation with respect to the Si matrix. For higher temperature (800 and 900°C) anneals, most of the precipitates are transformed into β-FeSi2, accompanied by substantial precipitate coarsening. For platelet-shaped precipitates, the coarsening activation energy was determined to be 3.48 eV.
Reactions in Metal-Metalloid Multilayers
Authors: Sinclair Robert , Konno Toyohiko J. 
Published: March 2011

ABSTRACTWe have studied the reactions at metal-metalloid interfaces using high resolution transmission electron microscopy, including in situ observation, and differential scanning calorimetry. There is contrasting behavior depending on the affinity for interaction or segregation. For reactive systems, compound formation ultimately results, but this can be preceded by solidstate amorphization. For non-reactive systems, crystallization of the metalloid is often achieved with nucleation and growth mediated by the metal phase.
Electron Microscopy Study of Cubic Boron Nitride Thin Films Grown by Ion -Assisted Pulsed Laser Deposition
Authors: Medlin D.D. , Friedmann T.T. , Mirkarimi P.P. , Mccarty K.K. , Mills M.M. 
Published: March 2011

ABSTRACTWe present a microstructural study of boron nitride films grown by ion-assisted pulsed laser deposition. Fourier transform infra-red spectroscopy, electron energy loss spectroscopy, and electron diffraction measurements indicate that within the irradiated region of the substrate, the film consists of high fraction of cBN with a small amount of the turbostratic phase; outside of the irradiated region, only the turbostratic phase is detected. Conventional and high resolution electron microscopic observations of the boron nitride microstructure indicate that the cBN is in the form of twinned crystallites, up to 30 nm in diameter. We also observe particulates, formed by the laser pulse, that reduce the yield of cBN in the irradiated regions by shadowing local areas from the ion beam.
Mechanism of Intermetallic Phase Formation in thin Liquidsolid Diffusion Couples
Authors: Bartels F. , Muschik T. , Gust W. 
Published: March 2011

ABSTRACTThin interconnection layers entirely consisting of intermetallic phases have been produced by joining planar Cu substrates coated with thin films of Sn. The thin layers of intermetallic phases are produced at low temperatures (<300°C) and short reaction times (5-120 s) in a process similar to reflow soldering by a liquid-solid reaction between Sn and Cu. Metallographic methods and X-ray analysis have been used to characterize the initial stages of the formation of the intermetallic phases. The reaction to form intermetallic phases via Cu dissolution and diffusion in the liquid Sn is very fast in the first 10-15 s when the liquid Sn is in contact with the Cu substrate along channels of liquid Sn between grains of the intermetallic phases. The stability of these narrow channels of liquid Sn is discussed in terms of the wettability of different types of grain boundaries in the textured layer of intermetallic phases.
Phase Transformations in Cu-Zr Multilayers
Authors: Weihs T.T. , Barbee T.T. , Wall M.M. 
Published: March 2011

ABSTRACTA study of phase transformations is reported for Cu-rich, Cu-Zr multilayer foils that were synthesized using magnetron sputter deposition and annealed using a differential scanning calorimeter. The foils range in composition from 1.6 at% to 9.0 at% Zr and consist of alternate layers of polycrystalline Cu and Zr. Differential scanning calorimetry, X-ray analysis and electron microscopy were used to examine three distinct reactions in the foils: a mixing and an amorphization of the Cu and the Zr, a crystallization to the metastable intermetallic, Cu51Zr14, and a transformation of the Cu51Zr14 phase into the equilibrium phase, Cu9Zr2. The asdeposited layering remained stable during the first two reactions and then broke down in the third reaction as large grains of Cu9Zr2 encompassed the smaller Cu grains. The heats of the reactions and the activation energies of these reactions are measured and are compared to values reported for bulk samples. The measured heats support the observation that amorphous Cu-Zr alloys phase separate and provide evidence that mixing and short range ordering produce 3.5 times more heat than long range ordering when Cu and Zr react and form Cu51Zr14.
Structural Properties of Anisotropic PtCo(001) and PtFe(001) Thin Films on MgO(001)
Authors: Lairson Bruce M. , Visokay Mark R. , Brennan Sean B. , Sinclair Robert , Clemens Bruce M. 
Published: March 2011

ABSTRACTWe report structural properties of PtFe and PtCo intermetallic compounds with perpendicular magnetic anisotropy and a preferred c-axis orientation perpendicular to the film plane, formed from initially epitaxial multilayers. These materials represent particular cases of a more general class of anisotropic magnetic compounds with the CuAu(1) natural superlattice structure. They possess high magneto-optic Kerr rotations and magnetizations, suggesting them as likely candidates for magneto-optic and perpendicular magnetic recording media.