bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bismaleimide/Allylnadic-Imide Blends Yield Low Dielectric Constant And Low Water Uptake
Authors: Ansermet J-PH , Kramer A. 
Published: March 2011

ABSTRACTThe bismaleimide resin Matrimid 5292A (I) was cocured with an allylnadic-imide resin (EP 433) which contained a long aliphatic chain as backbone (II). Water uptake, swelling, and the dielectric properties (up to 300 MHz) were studied in cast plates. The dielectric constant varied from 5.4 in (I) to 3.2 in (II) at water saturation, compared to 3.1 in (I) to 2.7 in (II) in the dry state. The glass transition temperature stayed above 200 °C at less than 80 mol% of (II).
Characterization Of The Binding of Inorganic Polymers To Oxide Surfaces By NMR and NMR/MAS Spectroscopy
Authors: Burton Sarah D. , Samuels William D. , Exarhos Gregory J. , Linehan John C. 
Published: March 2011

ABSTRACTSolution and solid state Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) spectroscopy have been used to monitor the 31P signal of cyclic phosphazenes and associated linear polymers in solution and of these materials bound to alumina in stabilized dispersions. The differences between the simple solution experiments and the suspensions are being studied to determine the viability of NMR techniques to probe the chemical interactions between inorganic polymer dispersants and alumina particles. It has been observed in colloidal suspensions that the adsorption of phosphazenes onto an aluminum oxide surface causes a broadening of the 31P signal in solution NMR. This broadening is dependant on the amount of solid to polymer concentration, the amount of solids loading, the solvent polarity and the phosphazene substituent under investigation [1]. Conversely, the solid MAS experiments show a narrowing of the 31P signal upon adsorption of the phosphazene to alumina.
The Determination Of The Residual Stress State And Its Effect On Peel Tests In Polyimide Coatings.
Authors: Farris Richard J. , Maden Michele A. , Goldfarb Jay , Tong Kun 
Published: March 2011

ABSTRACTThe determination of residual stresses in thin polymer coatings is crucial in the prediction of failure due to delamination and cracking. This is especially important in the electronics industry where thin polymer dielectric layers are used. The dielectric layers are often under three-dimensional constraints and have holes through which metal interconnects run. These act as locations of high stress concentration. Three complementary methods have been developed which will provide a better base for understanding the delamination and performance of thin coatings.These techniques include, a holographic interferometry method for determining the residual stresses in coatings (˜10 μm thick); a deformation calorimetry technique for establishing an energy balance for peel tests; a set of experiments for measuring the nine elasticity coefficients for orthotropic films. The combination of these methods allows a comparison between the residual stresses present in coatings and the contribution of those residual stresses to the work needed for peeling. The knowledge of the stress state and elasticity coefficients is essential for determining the elastic energy in a coating. The total elastic energy which can be stored in a stressed coating increases with the coating thickness. Stressed coatings exceeding a critical thickness will spontaneously delaminate if the elastic energy in the coating is greater than the energy required for debonding. The elastic energy in the coating per unit area at the critical thickness is a measure of the interfacial strength.
Changes In The Characteristics Of The Free Volume Of Glassy Polymers During Deformation And Relaxation.
Authors: Tsapovestsky M.I. , Lavrentiev V.K. , Tishin S.A. 
Published: March 2011

ABSTRACTThe behavior of glassy polymers was studied with the aid of mechanical tests on the basis of free volume. Three types of experiments were carried out and interpreted using modern ideas about the structure of free volume. They were: 1. The study of changes in the total free volume occurring as a result of deformation (by measurement of density) 2. The study of micro voids and their changes on deformation using small angle X-ray scattering (SAXS) and positron annihilation 3. The study of mobile regions by the measurement of dielectric loss (using an original interpretation) during deformation. This allows several parts of the total free volume to be distinguished and investigated. A model for the free volume relaxation during deformation is proposed.
UV-Laser Photoablation Of Thermostable Polymers: Polyimides, Polyphenylquinoxaline and Teflon AF
Authors: Lazare Sylvain , Hiraoka Hiroyuki , Cros Alain , Gustiniani Régis 
Published: March 2011

ABSTRACTThe UV laser ablation of three thermostable polymers, polyimide, polyphenylquinoxaline and Teflon AF of interest for microelectronics is presented. Direct absorption of the laser beam is not possible by Teflon, but a doping technique is described.
Adhesion Of Copper To Polytetrafluoroethylene Polymer Film With Adhesive Layers
Authors: Chan Chin-Jong , Chang Chin-An , Farrel Curtis E. 
Published: March 2011

ABSTRACTEnhanccd adhesion of Copper to spin-coated polytetrafluoroethylene PTFE.) film is achieved by employing an intermediate adhesive layer consisting of fluorinated ethylenepropylene (FEP) and metallic titanium. The peel strength of Cu on PTFE is low (1–2 g/mm) without the adhesive layer. After incorporating the Ti/FEP adhesive layer, a peel strength as high as 80 g/mm can be achieved. The overall peel strength is found to increase with the adhesive layer thickness. Thermal annealing at high temperatures strongly affects its overall peel strength. Previous XPS study indicated the formation of TiCx at the Ti/FEP and Ti/PTFE interfaces. Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy studies revealed that significant amount of Cu diffused into the FEP layer through the Ti layer when the specimens were heat treated at 375°C for various amount of time. Cu diffusion strongly affects the interfacial properties and hence results in the variation of overall peel strength. The results indicate that the thickness of Ti barrier as well as the heat treatment temperature are important for retaining the high peel strength.
Stiff Polyimides: Chain Orientation And Anisotropy Of The Optical And Dielectric Properties Of Thin Films
Authors: Boese D. , Herminghaus S. , Yoon D. Y. , Swalen J. D. , Rabolt J. F. 
Published: March 2011

ABSTRACTThin films of poly(p-phenylene biphenyltetracarboximide), prepared by thermal imidization of the precursor poly(amic acid) on substrates, have been investigated by optical waveguide, UV-visible, infrared (IR), and dielectric spectroscopies. The polyimide films exhibit an extraordinarily large anisotropy in the refractive indices with the in-plane index n║ = 1.852 and the out-of-plane index n┴ = 1.612 at 632.8 nm wavelength, indicating a strong preference of polymer chains to orient along the film plane. No discernible effect of the film thickness on this optical anisotropy is found in the range of ca. 0.4 μm to 7.8 μm in thickness. The frequency dispersion of the in-plane refractive index to 1.06 μm wavelength is consistent with the results calculated by the Lorentz-Lorenz equation from the UV-visible spectrum. The contribution from the entire IR range from 7000 to 200 cm,−1 computed by the Spitzer-Kleinmann dispersion relations from the measured spectra, adds ca. 0.07 to the in-plane refractive index n║. Approximately the same increase is assumed for the out-of-plane index n┴, based on the tilt-angle dependent IR results. Application of the Maxwell relation leads to the out-of-plane dielectric constant ε┴≃2.8 at ca. 1013 Hz, as compared with the measured value of ca. 3.0 at 106 Hz. Assuming this small difference to remain the same for the in-plane dielectric constants ε║, we obtain a a very large anisotropy in the dielectric properties of these polyimide films with the estimated in-plane dielectric constant ε║≃3.5 at ca. 1013 Hz, and ε.≃3.7 at 106 Hz.
Preparation And Characterization Of Thermoplastic/Thermosetting Polyimide Blends
Authors: Yamamoto Y. , Toyoshima T. , Etoh S. 
Published: March 2011

ABSTRACTThree kinds of thermoplastic/thermosetting polyimide blends have been prepared using three kinds of commercially available soluble polyimides(AL1051, PI2080, Ultem) and N, N′ – (methylenedi-p-phenylene) bismaleimide(BMI). The DSC thermograms of the polyimide blends showed exotherms at higher temperatures compared to BMI alone. The cure characteristics of the blends changed significantly according to the thermoplastic polyimide component. The fracture surfaces of PI2080 and Ultem blends, examined under a scanning electron microscope, showed distinct nodular morphological features. However, in the case of AL1051, which was derived from a aliphatic acid, this kind of phase separation was not observed. The mechanical properties of the blends were studied by using a thermomechanical analyzer. The blends yielded films with good mechanical properties even at high temperatures. The BMI component did not have any significant effect on the glass transition temperatures. However it showed improved mechanical properties at high temperatures. The blends were brittle compared with the thermoplastic polyimides. The tensile and electrical properties of the blends and their coefficients of thermal expansion were also studied.
Optical Waveguiding in Poled NLO Polymers
Authors: Swalen J. D. , Fleming W. , Jurich M. , Moerner W. E. , Smith B. A. , Herminghaus S. , Bjorklund G. C. 
Published: March 2011

ABSTRACTFor potential optoelectronic applications, new polymeric thin films
containing nonlinear optical chromophores aligned by electric field poling
for a χ(2) nonlinear optical response have been prepared and
studied. Spectroscopic and optical waveguiding techniques, as well as second
harmonic generation and electrooptic measurements, are being used to
characterize these thin film materials. Here we optimize the chromophores in
spectral response, nonlinearity, concentration and degree of alignment.
Stability in the nonlinearity has been improved considerably by attaching
the chromophores to crosslinked epoxy polymers. Some applications of these
materials for electrooptic phase modulators will be presented.
Electrooptic Coefficients in Electric Field Poled Polymer
Waveguides
Authors: Smith Barton A. , Herminghaus S. , Swalen J. D. 
Published: March 2011

ABSTRACTPlanar wavcguides were made from a linear epoxy copolymer of bisphcnol-A
diglycidyl ether and amino-nitro-tolanc. The refractive indices, ni-M and
n-E, and the clectrooptic coeflicients, r33 and r13,
of the poled nonlinear optical polymcr films were determined by measurements
of the wavcguide modes of these films at a wavelength of 632.8nm, and the
results arc reported for both electrode and corona poling. The ratio of the
second order susceptibilities was found to exceed significantly the
theoretically expected value of 3. Restricted motion of the nonlinear
chromophorcs during poling provides a possible explanation of this
discrepancy.
Nonlinear Optical Response of Nematic Droplets
Authors: Risser Steven M. , Ferris Kim F. 
Published: March 2011

ABSTRACTWe have used a finite element method to calculate the nonlinear polarization
of small nematic droplets, for both the radial and bipolar director
configurations. The nonlinear polarization of droplets with a radial
director is concentrated along the droplet axis, while for the bipolar
droplets, the nonlinear polarization is more uniform across the droplet. The
nonlinear polarization of the bipolar configuration has also been shown to
be sensitive to the angle between the droplet axis and the applied
field.
Photorefractive Nonlinear Optics
Authors: Feinberg Jack 
Published: March 2011

ABSTRACTPhotorefractive crystals are great for image processing, beam amplification,
and phase conjugation. I will describe these and a number of other new
applications of photorefractive crystals. I will also show how light beams
in these crystals are like politicians: if given the chance they will always
choose the path that maximizes their own gain.
Optical Information Processing with Quantum Well Seed's
Authors: Chirovsky Leo M. F. 
Published: March 2011

ABSTRACTThis is a review of how and why modem epilayer growth techniques have led to a novel class of optical devices, the Quantum Well SEED's, and of how and why these devices, in turn, have enabled experiments on novel system architectures in which digital information is processed or routed in parallel optically, to take advantage of the large space-bandwidth product of free-space optical interconnects.
Highly Strained (InAs)M/(GaAs)N Multiple
Quantum Well Based Resonant Tunneling Diodes on GaAs (100) Substrates and
Their Application in Optical Switching
Authors: Kapre R. M. , Hu Kezhong , Chen Li , Guha S. , Madhukar A. 
Published: March 2011

ABSTRACTWe report the realization of (a) an optically bistable switch using a
strained resonant tunneling diode (RTD) and (b) highly strained RTDs
exhibiting simultaneously high peak current densities (Jp) and
peak-to-valley current ratios (PVR) suitable for high-speed electronic
switching. Both of these make use of RTDs with
(InAs)M/(GaAs)N strained short period multiple
quantum well regions with AlAs barriers in a triple-well, double barrier
structure. For the former, high contrast ratio (20:1) and an on state
reflectivity of 46.5 % has been obtained at room temperature in an optically
bistable switch involving a strained InGaAs/GaAs (100) multiple quantum well
based asymmetric Fabty-Perot reflection modulator, detector, and a strained
RTD and a Si field effect transistor. For the latter, we have obtained a
Jp of 125 kA/cm2 with a PVR of 4.7 at room
temperature.
Epitaxial Structures For Optical Information Processing
Applications: Superlattice Infrared Detectors
Authors: Asom Moses T. 
Published: March 2011

ABSTRACTAdvances in epitaxial growth techniques such as molecular beam epitaxy and
metal organic chemical vapor deposition have facilitated the formation of
high quality III-V heterostructures with dimensional control down to atomic
levels, with abrupt doping and near-defect-free interfaces. The flexibility
and remarkable control offered by these techniques have resulted in the
fabrication of new devices based on confinement or modulation of carriers in
thin III-V heterostructures. Quantum wells and superlattice based devices
are expected to be utilized in optical information processing as sources,
modulators, and detectors. In this paper, we will review the general
epitaxial requirements for quantum wells and superlattices based devices,
and discuss the fabrication and properties of a new class of infrared
photodetectors that employ intraband transitions in quantum wells.
Buried Concentration Profiles for Optical Waveguides by One-Step
Electro-Diffusion Process: Theoretical Analysis
Authors: Li Xiaoming , Johnson Paul F. 
Published: March 2011

IntroductionIn recent years, a two-step electric field assisted diffusion or
ion-exchange technique has been extensively studied for producing buried
concentration profiles in glass [1,2,3], polymer [4,5], electrooptic and
semiconducting [6,7] substrate materials to fabricate buried optical
waveguide devices. The technique contains two separate diffusion processes
and is quite complicated, cost and time consuming. In addition, theoretical
analysis of the technique is too complicated to be used for calculating and
tailoring concentration profiles. Many efforts have been made to pursue a
one-step process for producing buried profiles. Very recently, a novel
one-step technique [8] involving electric field assisted diffusion of silver
ions into glass from molten AgNO3 bath with decaying silver
concentration has been developed to produce buried Ag+
concentration profiles in glass substrate. The new technique is, from the
practical operation point of view, relatively simple and is a significant
improvement over the conventional two-step process.
Homoepitaxial Growth of p-Type ZnSe Layers on Dry-Etched
Substrates
Authors: Ohkawa K. , Mitsuyu T. 
Published: March 2011

ABSTRACTWe have succeeded in the growth of p-type ZnSe homoepitaxial layers. The
layers have been grown by molecular beam epitaxy (MBE) on (100) ZnSe
substrates dry-etched with BCI3 plasma to eliminate polishing
damage. Nitrogen acceptors were incorporated by nitrogen radical doping
during MBE growth. Hall measurement by using Pt electrodes have indicated
that the N-doped ZnSe homoepitaxial layers are p-type with typical hole
concentration of 8.9×1015 cm−3. 12-K photoluminescence
(PL) from the layers exhibited strong neutral-acceptor-bound exciton
emission (11) at 2.7931 eV, indicating the peak energy of
11 emission from the strain-free ZnSe:N.
The X-Ray Spectral Microinvestigation of the Chinical States of
Atoms in CdxHg1-x Te/GaAs Thin Fiit.
Authors: Rezvitskii V. V. , Treicer B. A. , Bondarenko I. I. , Volkov L. A. , Mazalov L. N. 
Published: March 2011

ABSTRACTThe results of the x-ray spectral investigations of
CdxHg1-xTe/GaAs thin films conducted with the help
of “Camebax - microbeam” electron microprobe are presented. It is shown that
the sensitivity of the microprobe combined with the mathematical processing
based on the chemometric approaches Is sufficient to reveal the effects of
the chemical bond on x-ray spectra.
Highly Sensitive Absorption Measurements in Organic Thin Films:
Charge Transfer Complexes and Light-Induced Changes
Authors: Skumanich Andrew 
Published: March 2011

ABSTRACTUsing the sensitive absorption technique of Photothermal Deflection
Spectroscopy (PI1S) it is possible to detect subtle spectral features in the
absorption spectra of polymeric thin films that cannot be detected by other
means. This paper describes observations of weak charge-transfer complex
(CIC) formation and also light-induced changes in various organic films. The
filns studied were those commonly used as charge transport materials in
organic photoconductors, comprised of a small transport molecule and a
polymer binder. The optically measured CTC bands can be used to establish
single electron energy levels of the constituents. Reproducible
photo-induced changes are manifest both in the strong UV transitions as well
as in the “sub-gap” absorption and appear to be correlated with the
photo-chemical stability of the constituents. The light-fatigue has both a
reversible as well as irreversible component.
The Measurement of Thermal Conductivity of Ag/Al Multilayered Films
Authors: Kaizuka Takeshi , Soe We-Hyo , Yamamoto Ryoichi , Ohyama Masanori 
Published: March 2011

AbstractThe in-plane thermal conductivity of Ag/Al multilayered films was measured at room temperature by ac calorimetric method as a function of the modulation wavelength and was compared with the electrical conductivity. The electrical conductivity increases with wavelength, Λ, like other metallic multilayered films. The thermal conductivity also tends to increase with Λ, but the Λ dependence is not similar to that of electrical conductivity. Obtained Lorentz number value of the multilayers are almost 10–30% larger than that given by the free electron theory. The Wiedemann-Franz law did not hold in the Ag/Al films and the phonon contribution is not negligible.
Hrem Investigation of the Structure of the Σ5(210)/[001] Symmetric Tilt Grain Boundaries in Nb.
Authors: Campbell G. H. , Foiles S. M. , King Wayne E. , Rühle M. , Wien W. 
Published: March 2011

AbstractWe have simulated the atomic structures of the Σ 5 (210)/[001 ] symmetric tilt grain boundary using interatomic potentials for Nb developed employing the embedded atom method (EAM) and the model generalized pseudopotential theory (MGPT). These potentials do not predict the same lowest energy structure for the Σ 5 (210)/[001]. Using the ultra high vacuum diffusion bonding process, we have fabricated Σ 5 (210)/[001] bicrystals. The samples have been observed using high resolution electron microscopy and the observed images have been compared with those simulated based on the structures predicted theoretically. The experimental result for the Σ 5 (210)/[001] is in close agreement with the structure predicted using the EAM.
Grain Boundary Structure and Structure-Behavior Relationships in HCP Metals
Authors: King A. H. 
Published: March 2011

AbstractWe present calculations of dislocation spacing for grain boundaries in zinc, and show that the spacings may be large enough to be resolved in conventional transmission electron microscopy even at extreme deviations from ideal coincidence misorientations. This effect is a result of the need for the dislocation arrays to accommodate slight differences between the ideal and actual axial ratios in addition to the difference between the ideal and actual misorientations. Recent observations of sliding behavior as a function of misorientation may also be rationalized within the framework of our structure calculations.
Anomaly in the Hall Ooefficient of Ag/Cr Superlattices
Authors: Sato Hideyuki , Kumano Tadashi , Kaneko Takeo , Yamamoto Ryoichi 
Published: March 2011

AbstractThe Hall effect on Ag/Cr superlattice system has been investigated. When the Cr layer thickness is changed from 1 monolayer (ML) to 6ML for the same Ag layer thickness of 10 ML, the Hall coefficient (RH) varies anomalously. For 1 ML Cr sample, we obtained RH value close to that of pure Ag as expected. The absolute value of RH is enhanced with increasing Cr layer thickness. After having a negative peak near 3 ML Cr, it decreases at larger Cr thicknesses. The field dependence of the Hall resistivity is linear for all the samples, and there is no sign of long range magnetic order down to 1.5K.
X-Ray Photoelectron and Auger Electron Forward-Scattering Studies of the Epitaxial Growth of Fe on Ag(100).
Authors: Egelhoff William F. 
Published: March 2011

AbstractA controversy has arisen in the past year over whether or not the growth of Fe on Ag(100) at room temperature occurs by a layer-by-layer mechanism. The present work attempts to address this controversy with an investigation of the issues, primarily by x-ray photoelectron (XPS) and Auger electron forward scattering, but with important supporting data from low-energy electron diffraction (LEED), and reflection high-energy electron diffraction (RHEED) oscillations. The results of this work suggest that the origin of the controversy lies in different substrate preparation techniques which produce different atomic step densities on the Ag(100) surface. The step sites are implicated as being the initiators of major departures from a layer-by-layer growth mode whenever most of the deposited Fe atoms have sufficient mobility to reach these steps. However, even when the Fe atoms cannot reach these steps it appears that atomic place-exchange occurs with ≥25% of the top-layer Ag atoms. Atomic place-exchange mechanisms, which could account for this intermixing, have been observed in recent molecular-dynamics simulations of epitakial growth. Thus it seems probable that under the conditions that appear to produce layer-by-layer growth, the growth begins as layer-by-layer growth of an FeAg alloy, and only becomes layer-by-layer in pure Fe as the segregating Ag atoms gradually get left behind in the growing Fe film.