bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of the Electro-Optic Coefficient for Gallium Arsenide and Cadmium Telluride Modulator Rods
Authors: Herrit Gary L , Reedy Herman E. 
Published: March 2011

ABSTRACTCadmium telluride and gallium arsenide remain the only viable materials for electro-optic modulator applications in the 10 μm wavelength range. Primarily the modulators are used as Q switches, cavity dumpers, amplitude modulators, and frequency modulators for infrared applications, such as laser radar and guidance systems. Designers of optical and electrical systems incorporating these modulators require accurate values for the electro-optic coefficient, r41.A test arrangement, based on a modified version of the cross polarizer technique, was used to measure the electro-optic coefficients for cadmium telluride and gallium arsenide single crystals. The first part of this paper describes our test arrangement for measuring the r41 coefficient. The second part of the paper will discuss the test results. The r41 coefficient for CdTe was found to be 5.5 × 10−12 m/V in the unclamped region and 4.1 × 10−12 m/V in the clamped reion. Values for the r41 coefficient in GaAs were found to be 1.3 × 10−12 m/V and 1.9 × 10−12 m/V in the unclamped and clamped regions, respectively. All measurements were at 10.6 μm. Also investigated are the piezoelectric resonance values for both materials and the effect the resonances have on the measured r41 coefficient in the clamped and unclamped regions.
Diamondlike Carbon as a Moisture Barrier and Antireflecting Coating on Optical Materialst
Authors: Woollam John A. , De Bhola N , Chen L. Y. , Pouch John J. , Alterovitz Samuel A. 
Published: March 2011

IntroductionDiamondlike carbon (DLC) is amorphous, hard, semitransparent, and is under consideration for use as a coating material for infrared optics DLC is also designated as a-C:H to indicate its amorphous nature as well as to indicate the presence of large (20 to 55 percent) amounts of hydrogen in the film.
Characterization of Ti:LiNbo3 Optical Channel Waveguides Fabricated using Rapid Thermal Annealing
Authors: Ramabadran Uma , Brabander Gregory N. De , Boyd Joseph T. , Jackson Howard E. , Sriram S. 
Published: March 2011

ABSTRACTRapid thermal annealing has been used to initiate diffusion of Ti in LiNbO3 for the fabrication of optical waveguides. The sample with the most rapid initial ramp of temperature to 875 C was found to have the lowest propagation loss of 1 dB/cm. In order to more fully understand these channel waveguides, we have utilized Raman microprobe spectroscopy. Preliminary results suggest that the presence of the Ti in the LiNbO3 lattice dramatically alters the Raman response.
A few Problem in the Vapor Deposition of Diamond
Authors: Setaka Nobuo 
Published: March 2011

ABSTRACTRecently, there is considerable interest in semiconductor diamond films prepared by vapor deposition. The fact originates from their unique properties and potential for the devices operating at high temperature and high power. What diamond films were feasible by vapor deposition, provide the driving force for developing diamond for advanced electronic devices. However, there exist many large barriers. Their presence tends to de-press futher progress in the investigation and industrialization.The purpose of this paper is to point out the problems actually encountered in developing it and to describe its future direction on the basis of my present understanding.
Moisture and Plastic Package Stability
Authors: Kinsman K.R. , Jahsman W.E. , Sundahl R.C. 
Published: March 2011

AbstractPolymers used to encapsulate microelectronic devices absorb moisture – it's their nature. But only recently, with the growing use of surface mount technologies, has this phenomenon fostered concern much beyond the traditional chemical (corrosion) issues. The mechanical stability of plastic encapsulated components in use is now affected by moisture and its complex relation to interfacial adhesion and stress distributions within the package under different environmental (test) conditions. Strategies to defend against moisture-associated problems involve control of the application environment (removing moisture), improving package structural designs (increasing robustness), and managing materials choice to reduce moisture sensitivity. Each strategy has limitations, both physical and practical (economic), and all currently are being pursued. This paper will review the technical challenges, with particular emphasis on the state of affairs with regard to material development and application.
Low Dielectric, Hydrophobic Polyimide Homopolymers and Poly(Siloxane Imide) Segmented Copolymers for Electronic Applications
Authors: Arnold C. A. , Chen Y. P. , Chen D. H. , Rogers M. E. , McGrath J. E. 
Published: March 2011

AbstractPolyimides generally possess excellent thermal and mechanical properties, making them attractive candidates for high performance applications. To be useful for microelectronic applications, however, these materials must also be good insulators, as well as be readily processable.The incorporation of flexible polysiloxane segments into the polyimide backbone structure has been shown to yield soluble, processable copolyimides with good thermal and mechanical properties. In addition, the siloxane component imparts a number of other significant benefits for electronic applications. These include reduced water sorption, surface modification, good thermal and ultraviolet stability, and resistance to degradation in oxygen plasma environments. For polar polyimide systems, siloxane incorporation will also reduce the dielectric constant. The use of other less polar, more hydrophobic monomers will consistently yield soluble systems with lower dielectric constants as well.In this work, a series of high molecular weight, soluble polyimide homopolymers and segmented polysiloxane-polyimide copolymers were synthesized by a solution technique. The solution procedure, conducted at lower temperatures (˜170°C) than the classical bulk thermal imidization (300°C), has been shown to yield polyimides of enhanced solubility. In order to further enhance processability, molecular weight was controlled through the incorporation of monofunctional reagents such as phthalic anhydride and maleic anhydride, yielding nonreactive or potentially reactive endgroups, respectively. A series of maleic anhydride terminated imide oligomers with varying molecular weights were synthesized based upon the hexafluoropropane linked dianhydride and bisaniline diamine. In their oligomeric state, they exhibited enhanced solubility compared with their linear high molecular weight analogue. As these monomers were relatively nonpolar and hydrophobic, they afforded polyimides of low dielectric constant and a low level of water sorption. After thermally crosslinking the endgroups, the advantages of insoluble network systems could be realized. Particular advantages for electronic applications include thermal and dimensional stability over a wide temperature range, good mechanical properties, and chemical resistance. Structure-property characterization, including water sorption, dielectric constants, solubility behavior and thermal/mechanical properties will be reported.
Acetylene-Terminated Polyimide Composites for Advanced Electronic Packaging Applications
Authors: Ibrahim A. Mahammad 
Published: March 2011

AbstractSurface mount technology (SMT) is an electronic packaging technology wherein the leads of electronic components are soldered directly to metallized pads on the surface of a printed circuit board (PCB). The SMT with leadless ceramic chip carriers (LCCCs) is used to design, fabricate, and assemble affordable, high-speed, high-density electronic modules with reduced size and weight and improved electrical performance. In surface mount devices, the LCCCs are soldered directly onto the fabric composite PCB substrate. New high-performance composite substrate materials must be developed to take full advantage of SMT. Fabricating a PCB that will perform reliably throughout its intended life is also an increasingly important requirement, especially if the goal is to satisfy the high reliability required in military applications. Consequently, SMT is driving the development of PCB substrate materials with improved thermal and electrical properties. In our continuing effort to meet these military demands, we evaluated high-temperature resistant/high-performance acetylene-terminated polyimide composites for use in SMT PCBs. This paper focusses on the processing and on the thermal, thermomechanical, and dynamic mechanical properties data developed for these acetylene-terminated polyimide composites for their potential evaluation as PCBs. The characterization includes such properties as in-plane coefficient of thermal expansion (CTE), out-of-plane CTE, and glass transition temperature (Tg), which determine the solder joint reliability, plated-through-hole (PTH) reliability, and dimensional stability.
FTIR and XPS Studies of Polyimide/Metal Interface Formation
Authors: Stewart William C. , Leu Jihperng , Jensen Klavs F. 
Published: March 2011

AbstractWe describe infrared and x-ray photoelectron spectroscopy studies of the interfaces formed when the PMDA/ODA polyamic acid is imidized on gold, chromium, and copper. Polyimide films ranging from 34 Å to 1328 Å are analyzed as part of these studies. The IR and XPS results indicate that the gold interacts very little with the polyimide, while copper produces significant changes in the IR and XPS spectra. At elevated cure temperatures passivated chromium also reacts with the polyimide. In structures with chromium and copper, the thermal stability of the polyimide at the interface is reduced from that of bulk polyimide. The data demonstrate that the metals interact with the polymer structure at the point where ring closure occurs to form the polyimide from polyarnic acid.
Control of Thin Film Materials Properties Used in High Density Multichip Interconnect
Authors: Rechell J.J.H. 
Published: March 2011

AbstractMost literature on High Density Multichip Interconnect (HDMI) focuses almost exclusively on processing of the organic dielectric. Nevertheless, it is only one of the components in High Density Multichip Modules.Substrate properties, metal dielectric adhesion, internal stresses in the various films, and many other physico-chemical properties of the materials, can all be affected by neighbouring layers or process parameters improperly identified. Thus, in the course of process development, the real causes of difficulties and observed phenomenas can easily be misconstrued.This paper reviews some of the relationships between the properties of the thin film metallization and their effects on the dielectric layers. It also points out to some of the difficulties that can occur when treating the dielectric and the metallic layers as separate issues.
Investigations into the use of Adhesives For Level-1 Microelectronic Interconnections
Authors: Hogerton Peter B. , Hall J. B. , Pujol J. M. , Reylek R. S. 
Published: March 2011

AbstractIn relation to other surface mounting methods for bare integrated circuits, Flipped Direct Chip Attachment (FDCA) provides the most compact level-1 interconnection. High performance adhesives represent an interesting alternative to solders and conductive pastes, which are now being used for FDCA interconnections. These materials may provide the ability to achieve higher interconnection density on a larger chip and at the same time provide encapsulation of the active face of the chip. They may also provide simpler and cleaner manufacturing processes, resulting in lower installed costs.The purpose of this paper is to describe recent findings that are relevant to the question of whether FDCA with adhesives is a viable concept. Experimental results are reported that provide a description of the characteristics of pressure engaged interconnections that were obtained using a proprietary structural adhesive system. In addition, results of a thermomechanical modeling study are reported that provide estimates of the thermal stress distribution in an FDCA adhesive bond.
Protective Coating of Integrated Circuits for Operation in Corrosive Environments
Authors: Charlson E.J. , Sabeti R. , Charlson E. M. , Yasuda H. K. 
Published: March 2011

AbstractThis paper describes the development of a technique for protecting non-hermetically packaged integrated circuits for use inside the human body. A two layer combination consisting of a thin adhesion-promoting primer of plasma polymerized methane covered with a thicker layer of Parylene®-C has been found to provide excellent protection during long term exposure to simulated body fluids under continuous DC bias. The process for synthesizing the two layer combination in continuous vacuum is described. Results from adhesion and electrical testing of passive test structures are given. A new technique for the formation of small openings in thick polymer coatings for neural stimulation and sensing sites of implantable sensors is described. The technique uses biased thin film resistors formed on the passivation layer to provide localized heated areas which prevent polymer deposition during synthesis.
Gravimetric Measurements of Moisture Uptake in Polyimide Films Used in Integrated Circuit Packaging
Authors: Denton Denice D. , Pranjoto Hartono 
Published: March 2011

AbstractPolyimide is used extensively in a variety of integrated circuit packaging applications. It is a good dielectric material with excellent planarizing capabilities, but like most polymers, it absorbs moisture. This hygroscopic behavior can lead to reliability problems in integrated circuit packages. The effects of variations in process history on moisture uptake are examined using gravimetric measurement techniques. In particular, the effects of cure schedule and exposure to high temperature/high humidity environments on steady state moisture uptake are reported. Steady state moisture uptake is shown to be a decreasing function of cure temperature. Moreover, the steady state moisture uptake in polyimide is greater after the samples have been “aged” in a high temperature and humidity ambient. Electrical measurements are used to examine the effects of cure temperature on diffusion kinetics of moisture in polyimide. The diffusion coefficient decreases with increasing cure temperature.
Processing and the Microstructure of SrTiO3-Based Bl Capacitors using Pb(Fe, W)O3 Ferroelectrics
Authors: Kuwabara Makoto 
Published: March 2011

ABSTRACTA preliminary experiment was conducted to prepare semiconducting strontium titanate-based internal barrier layer capacitors with ferroelectric Pb(Fe, W)O3 forming insulating layers along the grain boundaries. Processing, microstructure and the dielectric properties of this new type of BL capacitors are described. The idea to obtain this type of BL capacitors with a very high dielectric constant may be realized when the ferroelectric materials can uniformly be diffused along the grain boundaries by using a more sophisticated processing of the second firing.
Plasma-Assisted Chemical Vapor Deposition of Ceramic Films and Coatings
Authors: Davis Robert F. 
Published: March 2011

ABSTRACTPlasma-assisted chemical vapor deposition uses energetic electrons to decompose reactant gas molecules into more simple and more highly reactant species to achieve deposition of amorphous and crystalline films and coatings at reduced temperatures. The basis of this technique, as well as the deposition conditions and properties of several ceramic films including Al2O3, TiO2, ZnO, AN, BN, TiN, SiC, Si, GaAs, SiC, C (diamond) and GaN, are briefly described. Modifications of the classical immersed method, including remote plasmas, the use of microwave frequencies and electron cyclotron resonance techniques, are also described with material examples.
Laser-Induced Materials Synthesis of Ultrafine Ceramic Particles from Specially Designed Molecular Precursors
Authors: Xiao Tongsan D. , Strutt Peter R. , Gonsalves Kenneth E. 
Published: March 2011

ABSTRACTThe investigation involved the synthesis of Si3N4surface layers on a Ti substrate by a specially designed organosilazane liquid precursor, (CH3SiHNH)xwith x=3 or 4, by pyrolysis with a 10.6 μm. continuous wave CO2laser. Microstructural examinations revealed that the particles of the nitride layers were spherical in shape with diameters ranging from 50 to 150 nm. Based on the experimental evidence, suggestions are made of possible mechanisms occurring during film deposition.
Powder Processing and Densification of Ceramic Composites
Authors: Lange Fred F. , Lam David C. C. , Sudre Olivier 
Published: March 2011

ABSTRACTTwo issues, packing powder/reinforcement systems and constrained densification, are reviewed. It is shown that pressure filtration has the greatest potential for packing powders containing reinforcements and packing powders within reinforcement preforms. High particle packing is achieved with repulsive interparticle potentials, and for a very small particle to reinforcement diameter ratio. It is now clear that individual reinforcements do not constrain the densification of powders. Shrinkage constraint is caused by a network of either nontouching or touching reinforcements. Network shrinkage (and thus composite shrinkage) caused by powder densification leads to the development of a denser interconnected matrix material surrounding lower density regions. Densification of the lower density regions requires the creep deformation of the denser continuum. As detailed elsewhere in this proceedings, grain growth causes this denser continuum to become more resistant to creep, and coarsening within the lower density regions causes desintering and the dissipation of sintering ‘stresses’. These phenomena do not occur during the densification of glass powders and explains the different densification behavior of crystalline powder matrices relative to glass powder matrices.
The Morphology of Freeze-Dried Rubidium Chloride Powder
Authors: Panitz J. K. G. , Voigt J. A. , Greulich F. A. , Carr M. J. , Eatough M. O. 
Published: March 2011

ABSTRACTWe have formed powders of a strongly ionic compound, RbCl by freezedrying. Stock solutions, varying from very low concentrations with 4 gm RbCl reagent dissolved in 100 cc water to saturated solutions with 80 gm reagent in 100 cc water, were sprayed into isopentane at -160°C. The droplet size in the spray was varied from relatively large 4-mm diameter droplets to extremely small droplets in an aerosol spray. It was determined that both the concentration of the stock solution and the droplet size affect the average size and the size distribution of the primary particles formed and the way in which these primary particles are bonded together. Unlike the powders of many less ionic compounds that are produced by freeze-drying, the primary particles in these RbCl powders are crystalline rather than amorphous. Analysis with an x-ray diffractometer with a cold stage indicates that crystallization occurs during the freezing cycle rather than during the sublimation period of the freeze-drying process.
(Y1−x)Ba2Cu3O6+δ (δ≤0.2): Consequences of Doping Tetragonal 123-Type to Induce Superconductivity
Authors: Parise John B. , Gai Pratibha L. , Crawford M. K. , McCarron Eugene M. 
Published: March 2011

ABSTRACTSubstitution of Ca(II) for Y(III) into tetragonal YBa2Cu3O6 has been achieved and a superconducting transition has been observed for a material of nominal composition (Y0.5Ca0.5) Ba2Cu3O6 (Tc (onset) ˜50K) [1]. Observations using high resolution electron microscopy show samples with x < 0.3 consist of a complex mixture, including (Y, Ca) Ba2Cu3O6+δ, YBa2Cu3O6+δ, and BaCuO2. Further, structural refinement using neutron diffraction data provide evidence of a solid solution limit at x ˜ 0.3. A direct analogy can be drawn between superconducting (Y1−xCax)Ba2Cu3O6 (0.1 < x < 0.3) and superconductors of the type (Y1−xCax)Pb2Sr2Cu3O8 and (La2−xM(II)x)CuO4. Substitution of the Ca(II) for Y(III) effectively increases the formal copper oxidation state. The refined structural model is fully consistent with partially oxidized CuO2 sheets separated by linear O-Cu(I)-O units.
Charge Transfer and Bond Lengths in YBa2Cu3−xMxO6+y
Authors: Miceli P. F. , Tarascon J. M. , Greene L. H. , Barboux P. , Jorgensen J. D. , Rhyne J. J. , Neumann D. A. 
Published: March 2011

ABSTRACTWe discuss the effects of doping on the Cu chain sites in YBa2Cu3−xMxO6+y. The relationship between bond lengths obtained from neutron scattering and charge transfer is evaluated in terms of bond valence. In particular, it is concluded that removing an oxygen from the chains transfers one electron to the planes.
Anisotropy in Normal and Superconducting Properties of Single Crystalline (La1−xSrx)2CuO4
Authors: Kitazawa K. , Kambe S. , Fukuoka A. , Naito M. , Tanaka I. , Kojima H. 
Published: March 2011

ABSTRACTTransport measurements were made on single crystals of (La1−xSrx)2CuO4 (x = 0.06 and 0.07) which have sizes large enough so that resistivity could be measured reliably along the c-axis by the usual 4 probe method. It was found that conduction along the c-axis was semiconductive in the low temperature orthorhombic structural region, while it was metallic in the high temperature tetragonal region. The resistivity in the basal plane, however, was not affected by the structural phase transition but could be fitted by the T1.3 dependence over the whole temperature range below 300K. The resistive superconducting transition was found to spread significantly under a magnetic field along the c-axis. But the degree of the spreading was essentially independent of the direction of the measurement current. The results suggest that LSCO is a typical 2D metal but with an unusual conduction mechanism and that its superconducting transition is overwhelmed by critical fluctuation under a magnetic field.
Photoemission Spectroscopy of Single Crystal HTSC Materials: A Fermi Liquid Electronic Structure
Authors: Arko A. J. , List R. S. , Bartlett R. J. , Cheong S. W. , Olson C. G. , Yang A. -B. , Liu R. , Gu C. , Veal B. W. , Liu J. Z. , Paulikas A. P. , Vandervoort K. , Claus H. , Campuzano J. C. 
Published: March 2011

ABSTRACTPhotoemission spectra from HTSC materials ( primarily 123 -type ), cleaved and measured at 20K, reveal a rich DOS structure which compares favorably with a calculated band structure, except for a residual 0.5 eV shift which may reflect some correlation effects. Band dispersion is observed throughout the valence bands, with clear evidence for a 0.2 eV wide band dispersing through EF. The orbital character at EF is a mix of Cu-3d and O-2p. There is unambiguous evidence for a large BCS-like gap (2Δ≥ 4kTc).
Electronic Picture in the Normal States of High-Tc Superconductors: From the Optical Viewpoint
Authors: Tajima S. 
Published: March 2011

ABSTRACTThe specific features of the optical spectra in the high-Tc Cu-oxides are discussed. The low-frequency spectral behavior can be explained by the highly correlated electronic model, whereas in the high-frequency spectrum the behavior of the Fermi liquid metal shows up.
Structure, Composition and Superconductivity of High Tc Tl–Ba–Ca–Cu–O System
Authors: Syono Yasuhiko , Kikuchi Masae , Nakajima Satoru , Suzuki Teruo , Oku Takeo , Hiraga Kenji , Kobayashi Norio , Iwasaki Hideo , Muto Yoshio 
Published: March 2011

ABSTRACTBulk high Tc superconductors of Tl2Ba2Can−1CunO2n+4 (n=1−4) and TlBa2Can−1CunO2n+3 (n=2−5) were synthesized, and their structures, chemical compositions and superconducting properties were studied by means of X-ray powder diffraction, electron probe microanalysis, transmission electron microscopy, and electrical and magnetic measurements. Superconducting critical temperatures are discussed in terms of average Cu valence and Cu-O bond length within the plane which vary with the number of Cu layers.