bluuebunny/crossref_metadata_2025_split huggingface dataset:
Processing Of PbTi03 And Pb(ZrxTi1−x)03 Thin Films By Novel Single-Solid-Source Metalorganic Chemical Vapor Deposition
Authors: Lu Ping , Li Hang , Sun Shan , Tuttle Brace 
Published: April 2011

ABSTRACTFerroelectric PbTiO3(FT) and Pb(ZrxTi1−x)03 (PZT) thin films have been deposited on (100) MgO and (111) Pt/SiO2/(100)Si substrates by using a novel single-solid-source metalorganic chemical vapor deposition (MOCVD) technique. The new technique uses a powder delivery system to deliver the mixed precursor powders directly into a hot vaporizer from room temperature, therefore, avoiding any problems associated with polymerization or decomposition of the precursors before evaporation. The technique simplifies MOCVD processing significantly and can improve process reliability and reproducibility. The deposited FT and PZT films have a perovskite structure and are highly oriented with respect to the substrate. With improvement of process control, systematic studies of film evolution under various growth conditions have been carried out. Effects of substrate, substrate temperature, system vacuum, and precursor ratios in the mixture on film microstructure and properties will be presented in this paper.
Equilibrium Domain Structures of Epitaxial Perovskite Ferroelectric Films
Authors: Pamir Alpay S. , Roytburd Alexander L. 
Published: April 2011

ABSTRACTPossible equilibrium domain structures due to elastic interactions between the film and the substrate as a result of a cubic-tetragonal transformation observed in epitaxial perovskite ferroelectric films are analyzed. The formation of both two- and three-domain states is taken into account. A stability map which shows domain stability regions as a function of temperature is developed in coordinates of misfit strain and tetragonality of the lattice of the ferroelectric phase. Misfit dislocation generation at the growth temperature is found to have a profound effect on domain selection. As an example a PbTiO3(001) film grown on a MgO(001) substrate is considered and theoretical findings are compared with experimental results in the literature.
Defect Generation And Evolution In The Hydrothermal Growth Of Epitaxial BaTiO3Thin Films
Authors: Zhao L. , Chien A. T. , Lange F. F. , Speck J. S. 
Published: April 2011

ABSTRACTThe structure of epitaxial BaTiO3thin films prepared by hydrothermal synthesis on (001) SrTiO3substrates was studied by transmission electron microscopy (TEM). The growth evolution was followed from initial island formation, through island impingement and fusion. Plan view and cross-section imaging demonstrated that the films grew by an unusual islanding mechanism. Electron diffraction showed the islands and the fully formed film are single crystal with mosaic character and in all cases strain relaxed. Cross-section TEM of the early growth films showed a several monolayer thick interfacial layer and the film/substrate region had no misfit dislocations. In the fully formed films, this interfacial layer was not observed, however a clear misfit dislocation network was observed. Defects analysis shows that the misfit dislocations have pure edge character with <100> Une directions, and <010> Burgers vectors (parallel to the film/substrate interface).
Correlations Between YBa2Cu3O7-δ Thin Film Materials Properties and RF Device Performance
Authors: Kaplan T. S. , Salazar M. T. , Huang Q. , Barfknecht A. , Lu Z. 
Published: April 2011

ABSTRACTBetter knowledge of the relationships between YBa2Cu307-δ (YBCO) materials properties and the RF performance of devices made from these materials should lead to improved device performance and yields. A variety of materials tests were performed on our production YBCO films which were patterned into standard microstrip resonators. The materials parameters were then compared with the unloaded Q of the resonators at 77 K. As expected, films with higher Q's tended to have higher Tc, higher Jc, greater film thickness, and better crystallinity. The last was based on narrower YBCO rocking curve peak, lower second phase density (judged by lower resistivity and greater θ-2θ (005) peak area), and a narrower θ-2θ (005) peak. The room temperature sheet resistance was found to be a useful predictor of microwave performance for films that are otherwise similar.
Submicron to Nanometer Size Single Particle Measurements
Authors: Barbara B. , Wernsdorfer W. , Orozco E. Bonet , Hasselbach K. , Benoit A. , Mailly D. , Demoncy N. , Pascard H. , Francois L. , Duxin N. , Pileni M.P. 
Published: April 2011

ABSTRACTLow temperature magnetization measurements of individual ferromagnetic particles and wires are presented (0.1 < T(K) < 6). The detector was a Nb micro-bridge-DC-SQUID, fabricated using electron-beam lithography. The angular dependence of the switching field could be explained approximatively by simple classical micromagnetic concepts (uniform rotation, curling…). However, dynamical measurements evidenced nucleation and propagation of domain walls, except for the smallest particles of about 20 nm. The variation of the mean switching field distribution (as a function of temperature and field sweeping rate) and of the probabilities of switching (as a function of temperature and the applied field) allowed to study in details the dynamics of magnetization reversal of individual particles. For sub-micron particles, we found that above a crossover temperature of 1K, the mean switching field and the switching probability follow a thermally activated model. For temperatures below IK, the dynamics of magnetization reversal becomes temperature independent which is interpreted in terms of deviations from the Néel-Brown model of magnetization reversal due to surface roughness and oxidazation. Although this crossovei temperature is much too large to be interpreted with current models of quantum tunneling, such an effect cannot be excluded. Measurements performed on ferromagnetic nanoparticles of good quality (single crystalline and with a diameter smaller than 25 nm), allowed us to show for the first time that the magnetization reversal can be described by thermal activation over the anisotropy energy barrier, as originally proposed by Néel. The observation of telegraph noise strengthens these results. Our measurements open the door to the observation of macroscopic quantum tunneling oí the magnetization in an individual particle containing 103-105 spins.
Transmission X-Ray Diffraction and Mössbauer Spectroscopy Study of Annealed Magnetoresistive Ag/Ni8iFei9 Multilayers
Authors: Bouat Sophie , Rodmacq Bernard , Auric Pierrette 
Published: April 2011

ABSTRACTWe have studied the variation of the structural and magnetic properties of 5-μm thick self-supported Ag/Ni81Fe19 multilayers upon annealing by means of transmission X-ray diffraction and Mössbauer spectroscopy as well as magnetoresistance (MR) and magnetisation measurements.In the virgin state, X-ray experiments show that both Ag and NiFe are (111) textured; the (220) in plane distances are 1.3 % smaller for Ag and 2 % larger for NiFe than the bulk values. Mässbauer spectra consist of a pure magnetic sextuplet, meaning that no non-magnetic layer is present at interfaces. The hyperfine field at 4.2 K is found only 3 % smaller than the bulk value and the Curie temperature is estimated from both Mossbauer and magnetisation at about 550 K.Upon annealing, the (220) Ag distance starts increasing above 250°C, whereas the decrease of the (220) NiFe distance starts at a much lower temperature. The densification of the NiFe layers is accompanied by an increase of the Curie temperature, without any effect on the magnetic moment; both this relaxation and the improved structural quality of the layering are responsible for the increase of the MR ratio from 12 % to 16 % after annealing at 240°C. Although the multilayer structure improves up to 320°C, the appearance of localised defects above 250°C leads to a rapid increase of the remanent magnetisation and to a decrease of the MR ratio.
Strong Non-Linear MCD-Effects Due to Partially Circular Polarized Light Sources
Authors: Höchst Hartmut , Zhao Dai , Huber David L. 
Published: April 2011

ABSTRACTMost soft x-ray magnetic dichroism studies are carried out with light of mixed polarization. The effect of incomplete circular polarization is usually taken care off by linearly extrapolating the data to Pcirc=l. Using a classical model which includes the polarization factor we show that the MCD-effect, which is the normalized quantity 2(I+-I-)/(I++I-), is highly non-linear with regard to cire. With a specially designed quadruple reflection phase shifter we measured the MCD effect with Pcire<l as well as with Pcirc∼1. MCD spectra of Fe around the M2,3 transition verify our model calculations of the polarization dependence. The data indicate that the observed non-linear response of the MCD-effect to Pcirc can generally introduce large errors in the quantitative analysis of MCD data where spin <Sz> and orbital <LZ> moments are extracted by means of sum rules.
Brillouin Light Scattering Study of Spin Waves of Ni and Co Films
Authors: Ngaboyisonga J.M.V. , Donzelli O. , Nizzoli F. , Canotti G. , Gubbiotti G. , Pareti L. , Tonili G. 
Published: April 2011

ABSTRACTThin films of Ni and Co have been investigated by Brillouin Light Scattering (BLS). The samples, grown by evaporation (Ni) and RF sputtering (Co) on silicon substrates, have thicknesses in the range 16–98 nm. The Damon-Eshbach surface mode and several bulk standing waves have been detected. A macroscopic approach has been adopted in order to calculate the dispersion relations of the spin waves. The method takes into account the dipolar and exchange interactions, together with bulk and surface magnetic anisotropies. The spin waves frequencies and the scattering cross section have been calculated by using the bulk and surface anisotropies as relevant fitting parameters.
Interrelation Between Structure and Magnetism of Ultra-Thin Mn Films Epitaxially Grown on (001) BCC Fe
Authors: Andrieu S. , Bauer Ph. , Fischer H. , Piecuch M. , Finazzi M. , Hricovini K. , Krill G. , Lefevre P. , Magnan H. , Chandesris D. 
Published: April 2011

ABSTRACTIn this paper, the interrelation between structural and magnetic properties of ultra-thin Mn films epitaxially grown on (001) bcc Fe is studied. The Mn growth and in-plane structure were controlled by electron diffraction (RHEED). The structures of the Mn films were determined by using X-Ray absorption spectroscopy (SEXAFS). Finally, the magnetic properties were studied by using X-Ray magnetic circular dichroïsm (XMCD). All the experiments were performed under ultra-high vacuum. As shown by XMCD experiments, a magnetic transition is observed at 2 Mn monolayers. The analysis of RHEED and SEXAFS experimental results clearly demonstrates that a structural transition comes with this magnetic transition.
Alteration of MCD Spectra Due to thin film Interference Effects
Authors: Rioux D. , Allen B. , Höchst H. , Zhao D. , Huber D.L. 
Published: April 2011

ABSTRACTMCD spectra at the M2,3 edge of thin Fe films exhibit thickness-dependent variations in line shape as well as in the absolute MCD-effect. Our data indicate that more information is contained in the MCD spectra than simply the evolution of a magnetic moment and ferromagnetic order. We developed a model to predict line shape modulations as a function of film thickness and angle of light incidence. Using the Fresnel-Maxwell formalism we calculate interference effects between left and right circularly polarized light reflected from the vacuum-film-substrate interfaces which are verified by our MCD measurements. Since the observed interference effects are a function of the excitation wavelength, our results can be directly scaled to show the significance of these effects in the more commonly used L2,3 region of 3d ferromagnets. Our data point out that one might be ill advised to rely onL2,3 MCD experiments to try to extract the formation of magnetic moments in films of several 10s of Å in thickness.
Properties of Magneto-Optical Co-Pt and Magnetoresistive Co-Cu Alloy Films
Authors: Lee Y. P. , Kim K. W. , Lee G. M. , Kudryavtsev Y. V. , Chang G. S. , Whang C. N. 
Published: April 2011

ABSTRACTCo-Cu films of 1000 – 1500 Å thick were produced by means of flash-evaporation technique at 150 K, 400 K, 520 K and 720 K. The Co022Cu078 films produced at 400 K or 520 K exhibit the maximum value of MR of 16.5% at 77 K and 1.5 T. Co-Pt films of 200 Å thick with Pt buffer layers of 200 Å thick were prepared at room temperature (RT) by ultrahigh-vacuum cosputtering. The saturation polar Kerr rotation angles (θk) at RT of CoPt3 film are all larger than those of the Co/Pt multilayered (ML) film of the corresponding composition. The surface morphology, mean grain and magnetic domain sizes, and size distributions of the grains and magnetic domains of the Co alloy films have been investigated by magnetic force microscopy (MFM) and atomic force microscopy (AFM). The results were correlated with those obtained by using MO and optical spectroscopy at both RT and low temperatures (LT) in a spectral ramge of 0.5 – 4.4 eV, and magnetic investigations at both RT and LT including field-dependence measurement of MR. The overall results reflect the changes in the electronic structures and magnetic states of the constituent elements, induced by the structural transformation or correlated with the structures of the films.
Metalized Polypropylene Film in Capacitors: Characterization and The Effect of Interfacial Pressure on the Dielectric Strength
Authors: Tandon Shalabh , Farris Richard J. 
Published: April 2011

AbstractMetalized polypropylene film used in high energy density capacitors has been mechanically characterized to determine its elastic constants. The out of plane coefficient of thermal expansion (CTE) of the orthotropic film is 10 times as large as the smaller in plane CTE. The out of plane modulus is twice as large compared to one of the in plane moduli. The effect of interfacial pressure on the dielectric breakdown is also studied for the same film. It is observed that the dielectric strength of the film decreases at first and then increases above 4 MPa of compressive stress.
Effect of Deposition and Annealing on The Thermomechanical Properties of Parylene Films
Authors: Todd Ryan E. , Miller Mikel , Ho Paul S. 
Published: April 2011

AbstractParylene polymers are vapor deposited and form semicrystalline films. The properties of these films vary with chemical structure, molecular weight, and morphology. The properties of parylene films deposited by changing the standard deposition process are evaluated and compared to control films. The thermomechanical properties of films produced by three modified processes, A, P, and PC, indicate the modified processes reduce the molecular weight. The films were also annealed to determine the stability of the film's properties during thermal cycling. These results also suggest that the modified films are lower molecular weight materials.
Effect of Post Plasma Treatment on Reliability and Dielectric Properties of SiOF Films Deposited by ECRCVD With SiF4 and O2
Authors: Lee Seoghyeong , Yoo Jae-Yoon , Oh Kyunghui , Park Jong-Wan 
Published: April 2011

AbstractThe effect of post plasma treatment on dielectric properties and reliability of fluorine doped silicon oxide (SiOF) films were investigated by measuring their C-V and I-V characteristics, XPS, AFM, and AES. The post plasma treatment of SiOF films was carried out in-situ at 300 °C in the deposition chamber. In this research, when the post plasma treatment time increased, we obtained the following results: (1) The etch rate of SiOF films decreased from 80Å/sec to 10Å/sec. (2) Surface roughness of the plasma treated SiOF films was increased due to the ion bombardment effect of the plasma. (3) The refractive index and relative dielectric constant increased from 1.391 to 1.461 and 3.14 to 3.9, respectively, due to the changes of surface chemistry by the post plasma treatment. (4) The leakage current density of SiOF films prepared by ECRCVD using SiF4 and O2 was less than 1 × 10−9A/cm2. (5) The breakdown field strength increased from 3.5 MV/cm to 8 MV/cm. (6) The thermal stability of the Cu/TiN/SiOF/Si system remained stable up to 600 °C.
Polynorbornene for Low K Interconnection
Authors: Grove N. R. , Kohl P. A. , Bidstrup-Allen S. A. , Shick R. A. , Goodall B. L. , Jayaraman S. 
Published: April 2011

AbstractWithin the microelectronics industry, there is an ongoing trend toward miniaturization coupled with higher performance. The scaling of transitors toward smaller dimensions, higher speeds, and lower power has resulted in an urgent need for low dielectric constant interlevel insulators. Low dielectric constant interlevel dielectrics have already been identified as being critical to the realization of high performance integrated circuits in the SLA Roadmap. Thus, there exists a need in the microelectronics industry for a thermally stable, noncorrosive low dielectric constant polymer with good solvent resistance, high glass transition temperature, good mechanical performance and good adhesive properties, particularly to copper. In addition, the desired dielectric material should be capable of being processed in environmentally friendly solvents, and the final thermal and electrical performance should not be affected by manufacturing or post environmental conditions. High glass transition temperature polynorbornenes are being developed which provide many of these desired features. This polymer family is produced via a new transition metal catalyzed polymerization. Attributes which make polynorbornene particularly attractive in microelectronics include: (i) excellent thermal performance, (ii) adhesion to conductors without the use of adhesion promoters or barrier layers, (iii) very low moisture absorption (< 0.1 wt %), and (iv) low dielectric constant (2.2 – 2.6). Side groups which have been added to the polynorbornene backbone improve adhesion, dielectric properties and mechanical properties.
Combined Tripod Polishing and Fib Method for Preparing Semiconductor Plan View Specimens
Authors: Anderson Ron , Klepeis Stanley J. 
Published: April 2011

AbstractCombining substantial pre-thinning of semiconductor device specimens via tripod polishing, followed by multiple, selective material removal steps with a focussed ion beam (FIB) tool, offers some unique possibilities with regard to preparing plan-view specimens at precise locations in the material below, and in the interconnect layers above, the semiconductor surface. Extension of these methods to other types of specimens in different configurations allows for the fabrication of multiple specimens on the same TEM grid that may not be possible by any other means.
Nucleation Modes in Sharp Concentration Gradients
Authors: Hodaj F. , Gusak A. M. , Kovalchuk A. O. , Desre P. J. 
Published: April 2011

ABSTRACTReaction kinetics in bimetallic multilayers have demonstrated that sharp unidirectional concentration gradient, which develop as interdiffusion proceeds at the interface are able to delay or to suppress nucleation of intermetallics. It has been found that the existence of a critical gradient beyond which nucleation is inhibited is strongly dependent on the mechanism of formation of the embryo [1–7].A mechanism of nucleation under concentration gradient (∇c) is proposed and treated on the basis of the Fokker–Planck equation for the distribution in the size space.The influence of the aspect ratio of the embryo on the critical concentration gradient is also studied. Due to the fluctuations of the embryo shape, it is shown that the minimization of the thermodynamic potential leading to the aspect ratio of the embryo is only significant beyond a certain value of the concentration gradient. Application is presented to the nucleation of the compound Ni10Zr7 in an amorphous layer Ni-Zr.
Particle Nucleation in Dissipative Systems
Authors: Russell K. C. , Rangel J. C. F. 
Published: April 2011

ABSTRACTDissipative regimes may induce athermal processes in addition to the thermally activated single atom addition or subtraction events considered by classical nucleation theory. Displacement cascades or impinging energetic ions could destroy sub-critical precipitates. Similarly, either displacement cascades or energetic knock-on atoms could remove single atoms or groups of atoms from subcritical clusters. Cluster injection is also possible, as in vapor deposition of clusters or in the cores of displacement cascades providing void nuclei.
Domain-Spatial Correlation Function of Spherulitic Domain Evolution in Polymer Films
Authors: Huang Tao , Tsuji Tomohiro , Kamal M. R. , Rey A. D. 
Published: April 2011

ABSTRACTWe present a new theoretical model of nucleation and growth in term of a novel domainspatial correlation function. This model probes the patterns and spatio-temporal evolution of nucleation and growth process and agrees very well with experimental data. The dynamic domain-spatial correlation function directly and simultaneously explores the transformed volume fraction, the time-dependent domain size distribution function, and the spatial correlation function of domain core centers for the entire process, including the post-nucleation, domain growth and grain formation stages.
Effects of Hafnium, Heat Treatment and Cycling under an- Applied Stress on The Transformations of Cold Worked Niti-Based Shape Memory Alloys
Authors: Zhan Chen , Zee Ralph H. , Thoma Paul E. , Boehm John J. 
Published: April 2011

ABSTRACTThe effect of thermal cycling under a constant tensile load on the transformation temperatures (TTs) of NiTi-based shape memory alloys (SMAs) is investigated. Three SMAs are examined in this study: a near equiatomic binary Ni49Ti51 alloy and two ternary Ni49Ti51-xHfx alloys with 1 at% and 3 at% Hf. The SMAs are in the form of wires with 40% cold work (reduction in area) and heat treated between 300°C and 600°C. These SMA wires are thermally cycled between their martensite (M) and austenite (A) phases for 100 cycles under an axial tensile stress of 206.8MPa (30Ksi) in air. Results show that the effect of thermal cycling on the M and A TTs depends on heat treatment (HT) temperature and composition in a complex manner. For example, the M TT, of the binary NiTi SMA heat treated between 300°C and 450°C, increases during thermal cycling. However, with HT temperatures between 500°C and 600°C, the M TIT decreases slightly during thermal cycling. For the NiTi-based SMAs that contain 1 at% and 3 at% Hf, the M TT increases during thermal cycling for HT temperatures up to 500°C, and the M TT decreases during thermal cycling when heat treated at 600°C. These results are due to changes in internal stress and structure, such as dislocation density and arrangement, which are affected by HT temperature and thermal cycling. The influence of Hf content on the changes in the M and A TTs during thermal cycling is also shown.
A Calorimetric Evaluation of the Role of Impurities in the Nucleation of Secondary Phases in 1xxx Al Alloys
Authors: Allen C. M. , O'Reilly K. A. Q. , Evans P. V. , Cantor B. 
Published: April 2011

ABSTRACTSuperpurity (> 99.995wt% pure) lxxx series Al-0.3wt%Fe-0.lwt% Si alloys with different impurity additions have been melt spun to produce ribbons with microstructures of fine scale ∼0.1–0.2μm diameter secondary phase particles entrained in a higher melting point Al matrix. The melting and resolidification behaviour at 2Kmin−1of the secondary phase particles while entrained in the solid matrix was monitored using differential scanning calorimetry, to simulate the nucleation of secondary phases in liquid interdendritic regions during the final stages of solidification in casting. The melting and resolidification behaviour of 500ppm V and Zr doped superpurity ribbons is the same as that of a commercial purity ribbon. This indicates that V is responsible for the promotion of the metastable FeAlmphase in the commercial purity ribbon. The presence of FeAlmin direct chill (DC) cast commercial purity alloys indicates that V also influences phase selection in the faster cooled (∼5-10Ks−1) regions of these alloys.