bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of CVR Coatings for PBR Fuels
Authors: Adams Jay W. , Barletta R. E. , Svandrlik J. , Vanier P. E.
Published: March 2011

As a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings for fuel particles which will be time and temperature stable. These coatings must not only protect the particle from attack by the hydrogen coolant, but must also help to maintain the bed in a coolable geometry and mitigate against fission product release. In order to develop these advanced coatings, a process to produce chemical vapor reaction (CVR) coatings on fuel for PBRs has been developed.

The initial screening tests for these coatings consisted of testing in flowing hot hydrogen at one atmosphere. Surrogate fuel particles consisting of pyrolytic graphite coated graphite particles have been heated in flowing hydrogen at constant temperature. The carbon loss from these particles was measured as a function of time. Exposure temperatures ranging from 2500 to 3000 K were used and samples were exposed for up to 14 minutes in a cyclical fashion, cooling to room temperature between exposures. The rate of weight loss measured as a function of time is compared to that from other tests of coated materials under similar conditions. Microscopic examination of the coatings before and after exposure was also conducted and these results are presented.
Synthesis of New Nitrides Using Solid State Oxide Precursors
Authors: Houmes Joel D. , Bem David S. , Loye Hans-Conrad Zur
Published: March 2011

Several novel transition metal nitrides were synthesized via ammonolysis of solid state oxide precursors at temperatures ranging from 700°C-900°C and reaction times ranging from 12 hours to 4 days. Both intermetallic nitrides, Fe3Mo3N and Co3Mo3N, and ionic/covalent nitrides, FeWN2, MnWN2, Ta5N6 and Nb5N6, were prepared by this method. The products were characterized by powder X-ray diffraction and their structures were determined by powder X-ray Rietveld refinement. The intermetallic nitrides were found to be isostructural with the eta-carbide structure, Fe3W3C, while the ionic/covalent nitrides have layered structures, with metals in octahedral and trigonal prismatic coordination environments. Two polymorphs of the MnWN2 composition, α-MnWN2 and β-MnWN2, were isolated after ammonolysis at 700°C and 800°C, respectively. While the alpha phase can be converted into the beta phase by heating to 800°C under ammonia, annealing the beta phase at 700°C did not result in a structural transformation. Magnetic measurements show that FeWN2 orders antiferromagnetically at 45K. The magnetic ordering temperature was confirmed by M6ssbauer spectroscopy. All the other nitrides were paramagnetic down to 5K. Conductivity measurements show that FeWN2 and MnWN2 are metallic.
Deposition of a-SiC:H Using Organosllanes in an Argon/;Hydrogen Plasma
Authors: Maya Leon
Published: March 2011

Selected organosilanes were examined as precursors for the deposition of amorphous hydrogenated silicon carbide in an argon/hydrogen plasma. The effect of process variables on the quality of the films was established by means of FTIR, Auger spectroscopy, XPS, XRD, chemical analysis, and weight losses upon pyrolysis. For a give power level there is a limiting feeding rate of the precursor under which operation of the system is dominated by thermodynamics and leads to high quality silicon carbide films that are nearly stoichiometric and low in hydrogen. Beyond that limit, carbosilane polymer formation and excessive hydrogen incorporation takes place. The hydrogen content of the plasma affects the deposition rate and the hydrogen content of the film. In the thermodynamically dominated regime the nature of the precursor has no effect on the quality of the film, it affects only the relative utilization efficiency.
Synthesis and Stabilization of Hexagonal Boron Nitride Materials
Authors: David Patrick , Mathiot Alain , Lulewicz Jean-Daniel , Narcy Bruno
Published: March 2011

Boron nitride presents many interesting properties for high temperature applications: high specific modulus, high electrical resistivity, electromagnetic transparency and strong chemical stability. However synthesis and densification by liquid or gas phase reactions (CVD, CVI or plasma processes) required for high technology applications (thermal shield, protective coating, microwave windows) are difficult to bring into play because material characteristics are strongly dependent on elaboration conditions. Boron nitride ultrafine powder synthesized by gas phase reaction in RF plasma (using NH3 and BCh3 at 800-1400°C) and composites obtained using a rapid densification process (vapor phase infiltration using trichloroborazole compound as precursor) have been studied. In both cases post synthesis heat treatment had to be performed in order to get stabilization of the material, and to avoid its hydrolysis. The stability has been related to the physical characteristics of the material. Thermodynamical studies using Gibbs energy minimization calculations were helpful to determine synthesis and heat treatment conditions.
Enhancement of Oxidation Resistance of Silicon Carbide by High-Dose and Multi-Energy Aluminum Implantation
Authors: Yang Zunde , Du Honghua , Libera Matthew , Withrow Stephen P. , Casas Luis M. , Lareau Richard T.
Published: March 2011

High-dose and multi-energy aluminum implantation of α-SiC (0001) was carried out to achieve a broad aluminum distribution extending from the sample surface to a depth of approximately 350 nm. Oxidation resistance of the implanted crystals was studied in 1 atm flowing oxygen at 1300°C. Aluminum implantation resulted in a 45% improvement in the oxidation resistance of α-SiC as compared with unimplanted crystals due to the formation of structurally dense mullite (3A12O3.2SiO2) in the oxidation scale.
One-Step Synthesis of Dithiocarbamates from Metal Powders
Authors: Hepp Aloysius F. , Hehemann David G. , Duraj Stan A. , Clark Eric B. , Eckles William E. , Fanwick Phillip E.
Published: March 2011

Neutral metal dithiocarbamate complexes (M(NR2CS2)x) are well-known precursors to metal sulfides, a class of materials with numerous technological applications. We are involved in a research effort to prepare new precursors to metal sulfides using simple, reproducible synthetic procedures. We describe the results of our synthetic and characterization studies for M = Fe, Co, Ni, Cu, and In. For example, treatment of metallic indium with tetramethylthiuramdisulfide (tmtd) in 4-methylpyridine (4-Mepy) at 25°C produces a new homoleptic indium (III) dithiocarbamate, In(N(CH3)2CS2)3 (I), in yields of over 60%. The indium (III) dithiocarbamate was characterized by X-ray crystallography; (I) exists in the solid state as discrete distorted-octahedral molecules. Compound (I) crystallizes in the Plbar (No. 2) space group with lattice parameters: a = 9.282(1) A, b = 10.08 1(1) Å, c = 12.502 Å, ∝ = 73.9 1(1)°, β = 70.21(1)°, γ = 85.84(1)°, and Z = 2. X-ray diffraction and mass spectral data were used to characterize the products of the analogous reactions with Fe, Co, Ni, and Cu. We discuss both use of dithiocarbamates as precursors and our approach to their preparation.
Processable, Chemical Routes to Binary Metal Sulfides
Authors: Rees William S. , Krauter Gertrud
Published: March 2011

Metal thiolates of the general formula M(SR)2(M = Pb, Zn, Cd) and Cl-Hg-SR (R = alkyl) have been prepared and characterized by spectroscopic techniques, TGA and, in selected cases, single crystal X-ray diffraction. The metalbis(thiolate) compounds can be converted into the related metal sulfides by thermolyses. The solid state materials have been characterized by XRPD, SEM and, in selected cases, by particle size determination. The volatile pyrolytic co-products have been isolated and characterized by GC/MS. The decomposition pathways of mercury chlorothiolates are more complicated and depend on the nature of the organic group present in Cl-Hg-SR.
The Crowdion Spreading and Radiation Stability Possibility of Non-Oxides
Authors: Koshkin Vladimir M. , Dmitriev Yuri N.
Published: March 2011

The paper suggests a criterion for selection of radiation stable semiconductors and dielectrics.

The search for materials with great radiation stability (RS) is one of the basic problems in materials science. The absolute RS of crystals could be provided only in case when all elementary radiation defects (Frenkel pairs) are unstable, and annihilated immediately at any low temperatures in the places whete they were born. The presence of an instability zone (IZ) of point defects vacancy (v) - interstitial atom (i) is a necessary condition for RS [1,2]. The characteristic radius r0 of IZ at v-i Coulomb interaction is on the order of 10-30 Å [3]. The important parameter is a mean distance x between stopping point of atom i, knocked out from its site, and the v born at this site. Without taking into account the periodic structure, the analytical expression for x was obtained[4]. The value of x appears to be not large. For example, if the knocked out atom has the energy of 10 keV, the mean distance between v and i is 10 Å in iron, and only 3 Å in copper (x < r0). So, the greatest part of i's seem to remain in IZ, and therefore must recombine with “their” own v's. This would result in RS being greater than what was really observed in majority of nonmetal crystals.
Chemical Bond Distribution and Short Range Order in Non-Oxide Ciialcogenide Glasses. Results from NMR Spectroscopy
Authors: Tepe Thomas , Lyda Carri , Tullius Michael , Lathrop David , Leone Jason , Eckert Hellmut
Published: March 2011

Solid-state 31p MAS-NMR provides powerful insights into the local order of phosphorus selenide based glasses. Specifically, it allows a quantitative characterization of the melt equilibrium PSe3/2 + Se -> Se=PSe3/2 describing the stability of four-coordinate P atoms. Using this technique, the effect of isovalent substitution by As, and Te, and of other glass constituents Ge and TI on this equilibrium and on the quantitative phosphorus speciation is studied in detail.
Scanning Probe Microscopy Study of Layered Dichalcogenide ReS2
Authors: Kelty Stephen P. , Ruppert Albert F. , Chianelli Russell R. , Ren Jingqing , Whangbo Myung-Hwan
Published: March 2011

Single crystal ReS2 was characterized using atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The observed atomic-resolution AFM and STM images were interpreted by calculating the total, p(r0), and partial electron density distribution, p(r0, ef), respectively, of a single ReS2 layer. The experimental and theoretical results indicate that the basal plane surface state density is dominated by contributions from the sulfur layer This is in contrast to bulk band structure calculations which would predict that the major contribution to the STM images should be from the Re atoms. Furthermore, the surface-to-tip STM images are found to be quite different from tip-to-surface images. By interpreting STM and AFM data from p(r0) and p(r0, ef) calculations, it is shown that site specific structural and electronic details of the surface can be elucidated.
The Synthesis of Polycrystalline Chalcopyrite Semiconductors by Microwave Irradiation
Authors: Landry Christopher C. , Barron Andrew R.
Published: March 2011

Polycrystalline samples of the chalcopyrites CuInS2, CuInSe2, AgInS2, and AgInSe2 have been prepared from stoichiometric mixtures of the pure elements using microwave irradiation. The reactions were performed in sealed quartz tubes in as few as three minutes. The products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and X-ray photoelectron spectroscopy (XPS). The surface morphology and shape of the particles produced by this method suggests that the products are formed from liquid melts.
Strategies for Crystal Engineering of Polar Solids
Authors: Zaworotko Mike , Subramanian S. , Macgillivray L. R.
Published: March 2011

Crystal engineering has been invoked to design structural analogues of two prototypal SHG active solids, p-nitroaniline (pNA) and potassium dihydrogenphosphate (KDP). pNA exists as linear polar strands because of head-to-tail hydrogen bonding between adjacent molecules whereas KDP is a self-assembled hydrogen bonded diamondoid network that becomes polar when the hydrogen bonds align. We detail preparation and crystallographic characterization of two classes of multicomponent solid, organic cation hydrogen sulfates and cocrystals of the cubane cluster [M (CO)3(μ3-OH)]4, which structurally mimic pNA and KDP, respectively. Several of the Multi-component solids are polar and they represent a generic approach to designing new polar materials since one component can be changed without altering the basic architecture within the crystal.
Molecular-Level Control in The Deposition of Ultrathin Films of Highly Conductive, In-Situ Polymerized P-Doped Conjugated Polymers
Authors: Fou A. C. , Ellis D. L. , Rubner M. F.
Published: March 2011

A novel thin film processing technique has been developed for the fabrication of ultrathin films of conducting polymers with angstrom-level control over thickness and multilayer architecture. Molecular self-assembly of in-situ polymerized conjugated polymers consists of a layer-by-layer process in which a substrate is alternately dipped into a solution of a p-doped conducting polymer (e.g. polypyrrole, polyaniline) and a solution of a polyanion. In-situ oxidative polymerization produces the more highly conductive, underivatized form of the conjugated polymer, which is deposited in a single layer of precisely controlled thickness (30 to 60 Å). The thickness of each layer can be fine-tuned by adjusting the dipping time and the solution chemistry. The surface chemistry of the substrate (e.g. hydrophobic, charged, etc.) also strongly influences the deposition, thereby making it possible to selectively deposit conducting polypyrrole onto well defined regions of the substrates. Typical multilayer films exhibit conductivities in the range of 20–50 S/cm, but samples with conductivities as high as 300 S/cm have been realized. There is no limit to the number of layers that can be built up nor to the complexity of the multilayer architecture of the film; achieved simply by alternating the sequence of dips into solutions of various polycations and polyanions. This new self-assembly process opens up vast possibilities in applications which require large area, ultrathin films of conducting polymers and, more importantly, in applications that can take advantage of the unique interactions achievable in the complex, supermolecular architectures of multilayer films.
Conducting Polymers: Past, Present and Future…
Authors: MacDiarmid Alan G. , Epstein Arthur J.
Published: March 2011

Since their discovery 16 years ago, the field of intrinsically conducing polymers — “synthetic Metals” — has developed at an unexpectedly rapid rate. The concept of “doping” is the unifying theme which distinguishes this class of organic polymers — “conducting polymers” — from all others. Doping results in dramatic electronic and magnetic changes with a concomitant increase in conductivity to, or approaching, the metallic regime. Doping phenomena and the chief types of dopable organic polymers are described with particular emphasis on polyaniline, which is now probably the most actively-studied conducting polymer. It has been commercialized on a relatively large scale and presently appears to be the leading conducting polymer for technology. It shows considerable promise for electromagnetic interference (EMI) shielding and as a gas separation Membrane, and is currently used in commercial rechargeable batteries. Polypyrrole is used commercially in capacitors and as an electrically conductive coating on conventional fabrics. Additional potential uses of conducting polymers such as light-emitting diodes, electrochromic windows, chemical sensors, etc. are also described briefly.
Solubility and Dispersion Characteristics of Polyaniline
Authors: Shacklette L. W. , Han C. C.
Published: March 2011

We have demonstrated that the solubility characteristics of undoped polyaniline can be understood from the point of view of standard solubility parameters which measure the propensity for the polymer and the solvent to engage in dispersive, polar, and hydrogen bonding interactions. By empirical measures and group additive calculations, emeraldine base has been shown to be characterized by solvent interaction parameters: δd = 17.4 MPa1/2, δp = 8.1 MPa1/2, and δh = 10.7 MPa1/2, which together are equivalent to a total solubility parameter: δ = 22.2 MPa1/2. In the case of doped polyanilines, the solubility parameters can influence or even dominate the interactions of the doped polymer. Without the modifying influence of the dopant anion, the doped polyaniline compositions are more strongly polar and hydrogen bonding than the undoped polymer.
Water Soluble Polyanilines: Properties and Applications
Authors: Angelopoulos Marie , Patel Niranjan , Shaw Jane M.
Published: March 2011

A new class of water soluble conducting polyanilines have been developed. This is accomplished by oxidatively polymerizing aniline monomers on a template such as a polymeric acid. The resulting polyanilines readily dissolve in water. These Materials can be applied as removable discharge layers for electron-beam (e-beam) lithography and for SEM Mask Metrology. Cross-linkable functionality can be incorporated on the polyanilinc backbone resulting in water soluble polyanilines that are radiation curable. Upon irradiation these materials cross-link and become insoluble and thus can be utilized as permanent conducting coatings for electrostatic discharge (ESD) applications. In addition, the cross-linkable polyanilines can be made into water developable conducting resists. 1.0μm conducting lines have been patterned with e-beam irradiation.
Conducting Polymers With Chemically Sensitive Traps And Barriers: New Molecule-Based Sensors
Authors: Swager Timothy M. , Marsella Michael J.
Published: March 2011

We present a general approach for the formation of conducting polymer based sensory materials which employ well-known Molecular recognition elements. These Methods are based upon impeding carrier transport through a conductive polymer's backbone with a barrier or by localizing a carrier with a trap. We have designed polythiophene derivatives which exhibit large changes in bandgap in the presence of specific ions. These Materials are based upon novel crown ether containing bithiophene monomers and we will discuss the details of the synthesis of the monomers and polymers. Sensory polymers which are selective for K+ and Na+ will be described. In such Materials, specific ions induce a twisting of the polymer's backbone.
Optical And Electrical Properties Of Doped Polysilanes
Authors: Kakimoto M. , Ueno H. , Kojima H. , Yamaguchi Y. , Nishimura A.
Published: March 2011

The doping effects on optical and electrical properties of polysilanes have been investigated by in-situ Measurement. An optical absorption associated with σ–σ* transition was observed near 330 nm for polymethylphenylsilane. By iodine doping, a new absorption was observed at the longer wavelength around 420 nm, which should originate from the charge transfer between dopant and Σ-conjugated system. Similar spectral changes have also been observed for most of investigated linear polysilanes.

Furthermore, we have found drastic spectral change upon iodine doping into polysilane with p-N,N-dimethyIaminophenyI substituent. It has very strong absorption up to 700 nm. It Might originate from a strong interaction between the substituent and iodine. At the same time, Σ-conjugation Might also play a significant role on doping into this system.
Descriptive Chemistry Of Self-Assembled Multilayer Second-Order NLO Materials. Chemical, Microstructural and Performance Interrelationships
Authors: Yitzchaik Shlomo , Kakkar Ashok K. , Roscoe Stephen B. , Marks Tobin J. , Lundquist Paul M. , Lin Weiping , Wong George K.
Published: March 2011

The construction of covalently self-assembled second-order nonlinear optical (NLO) Materials containing stilbazole or alkynyl-type high-β chromophores acentrically organized on inorganic oxide substrates is discussed. These structurally different chromophores exhibit differing packing densities on the surface when introduced under the same reaction conditions. In the stilbazolium chromophores, ion-exchange of the chloride counter-anion with very large anionie organic dyes results in appreciably enhanced second harmonic generation (SHG) efficiency. The frequency-dependent SHG response for self-assembled Monolayers derived from the alkynyl-type chromophore was also investigated. The linear absorption spectra exhibit two maxima in the visible region which are assigned to electronically isolated chromophores (480 nm) and aggregated species (540 nm). The dispersion of the second-order NLO coefficient reveals that both microstructures are NLO-active. The origin of the SHG response from both assemblies is discussed.
High Temperature Electrical Conductivity Of Solution-Cast Bbl Flims.
Authors: Agrawal Ashwini K. , Wang Chyi-Shan , Song Hyun H.
Published: March 2011

Thin films (18 μ thickness) of ladder polymer poly[(7-oxo-7H,10H-benz (d,e) imidazo (4′,5′:5,6) -benzimidazo (2,l-a) isoquinoline-3,4:10,ll-tetrayl)-10-carbonyl} (BBL), which were cast from an isotropie methanesulfonic acid solution of BBL, were characterized for electrical conductivity in the temperature range of 25–480 °C. The electrical conductivity was Measured in situ while the films were heated at a rate of 2 °C/Minute under vacuum. The in-plane conductivity of BBL films increased rapidly from below 10−10 S/cm at the room temperature to 5 × 10-3 S/cm at 280 °C and then increased slowly to a peak value of 5 × 10-2 S/cm at about 460 °C. The out-of-plane conductivity of the films was comparable to their in plane conductivity at temperatures below 270 °C, however, was lower by a factor of 10 than in-plane conductivity at temperatures above 270 °C. This anisotropy in conductivity of BBL films is discussed with respect to the film morphology determined by wide angle x-ray scattering studies.
Studies in The Organic Solid State
Authors: Whitesides George M. , Zerkowski Jonathan A. , MacDonald John C. , Chin Donovan
Published: March 2011

This paper describes an approach to crystal engineering based on designing and analyzing hierarchical levels of crystalline architecture. The system under study consists of 1:1 co-crystals of melamines and barbituric acids that self-assemble into crystallographically infinite hydrogen-bonded tapes. The formation of structural elements can be rationalized and controlled using familiar molecular concepts such as steric repulsion.
Space-Charge-Limited Charge Injection From Ito/Ppv Into A Trap-Free Molecularly Doped Polymer
Authors: Antoniadis H. , Abkowitz M. , Hsieh B. R. , Jenekhe S. A. , Stolka M.
Published: March 2011

We describe bilayer structures comprised of a poly (p-phenylene vinylene) (PPV) layer and a trap-free diaryldiamine (TPD) doped in polycarbonate (PC) layer, sandwiched between indium-tin-oxide (ITO) and aluminum (Al) contacts. Two critical phenomena in the operation of polymer based electroluminescent devices, interface injection and carrier range, are investigated. It is established that the ITO/PPV contact is capable of sustaining dark current under trap-free space-charge-limited (TFSCL) conditions into a hole transporting TPD:PC layer. TFSCL currents are not observed in devices without the PPV layer. Upon increasing the thickness of the PPV layer a deviation from the TFSCL regime is observed which is attributed to trapping of the injected holes within PPV. These observations suggest a novel method for estimating the trapping Mobility-lifetime product μτ for holes in PPV. By this means we estimate μτ ∼ 10−9 cm2/V.
Progress on Nonlinear Optical Chromophores and Polymers with Useful Nonlinearity and Thermal Stability
Authors: Twieg R. J. , Burland D. M. , Hedrick J. L. , Lee V. Y. , Miller R. D. , Moylan C. R. , Volksen W. , Walsh C. A.
Published: March 2011

Organic nonlinear optical (NLO) polymers must possess large and stable bulk nonlinear properties if they are to be of practical use. Numerous classes of NLO chromophores and polymers have already been evaluated but the selection process, particularly as related to stability issues, has been very stochastic in nature. If suitable chromophores are to be successfully identified their thermochemical degradation Mechanisms Must be elucidated and structural modifications introduced in a rational fashion. We have devised a protocol for the evaluation of NLO chromophores which involves initial screening by thermal analysis (DSC and TGA) and selected molecular hyperpolarizability (EFISH) analysis. The Most promising candidates are incorporated into thermoplastic polymer hosts where bulk nonlinear properties (dijand rij) and additional thermal stability properties are evaluated by spectroscopie Means (UV-VIS). Cyclicvoltammetry (CV) has been identified as a useful tool for evaluation of these chromophores; in the case of azobenzenes with aliphatic amine donor and a nitro acceptor a correlation between the thermal stability and oxidation potential has been found. The Most facile thermal degradation mechanism which occurs in these dyes has been identified and structural changes to the donor group have been introduced to avert the process.
Realization Of Large, Stable Second Order Optical Nonlinearities Through Double-EndCrosslinkable Chromophores
Authors: Xu C. , Wu B. , Dalton L. R. , Shi Y. , Ranon P. M. , Kalluri S. , Steier W. H.
Published: March 2011

We have developed a novel class of double-end crosslinkable (DEC) chromophores. Processible side-chain nonlinear optical (NLO) polymers with crosslinkable groups at the ends of chromophore pendants were synthesized from DEC Monomers. The polymers were processed into good quality films, which were subsequently poled with a corona setup and thermally cured to attain stable noncentrosymmetric order. Using this DEC approach, we have realized large optical nonlinearities (χ(2) = 90–220 pm/V) with long term stability at 125 °C.
Characterization Of Thermally Stable Dye-Doped Polyimide Based Electrooptic Materials
Authors: Meinhardt Michael B. , Cahill Paul A. , Seager Carl H. , Beuhler Allyson J. , Wargowski David A.
Published: March 2011

Preparation and characterization of novel dye-doped polyimide films for electrooptics is described. Thermal stabilities of donor-acceptor 2,5-diaryl oxazoles were evaluated by differential scanning calorimetry. Absorptive losses in thin films of Ultradel 9000D® doped with donor-acceptor oxazoles were measured by photothermal deflection spectroscopy. Absorptive losses at high doping levels may be explainable by dye-dye aggregation or dye degradation during the curing process. Lower doping levels, however, show losses of ≤ 3.0 dB/cm at 830 nm and ≤ 2.4 dB/cm at 1320 nm.
High Thermal Stability Electrooptic Chromophores And New Integrated Optical Polymer Devices
Authors: Yamada S. , Cai Y. M. , Shi R. F. , Wu M. H. , Chen W. D. , Qian Q. M. , Garito A. F.
Published: March 2011

A new class of high thermal stability fused-ring guest chromophores intended for incorporation into highly stable host polyimides has been successfully developed. Thermal stabilities far in excess of 300°C have been achieved for both the pure guest and the guest-host polyimide systems. The Microscopic second order nonlinear optical properties of the guest chromophores have been characterized both theoretically and experimentally. The achievement of the new high temperature EO chromorphores and polyimide formulations have directly resulted in the discovery of new EO device designs and architectures.
Second-Order Nonlinear Optical Polymers With Different Chromophore Arrangements
Authors: Wu Bo , Xu Chengzeng , Dalton Larry R. , Kalluri Srinath , Shi Yongqiang , Steier William H.
Published: March 2011

Second-order nonlinear optical polymers can be divided into four groups regarding arrangements of chromophore dipoles in polymer backbones, namely, side-chain polymers, random, head-to-tail, and head-to-head Main-chain polymers. A variety of polymers with the aforementioned configurations have been designed and synthesized from functionalized amino-nitro azobenzene chromophores. Poling processes of these polymeric materials have been investigated by in-situ poling and second-harmonic generation detection.
Sol-Gel-Derived Thin Films Incorporating An Organic Second-Order NLO Compound With Large βμ
Authors: Caldwell J. B. , Cruse R. W. , Drost K. J. , Rao V. P. , Jen A. K-Y. , Wong K. Y. , Cai Y. M. , Mininni R. M. , Kenney J. , Binkley E. , Dalton L. , Shi Y. , Steier W.
Published: March 2011

We have synthesized a new second-order NLO compound containing both the highly active tricyanovinyl electron acceptor group and appropriate funtionality for covalent bonding to an inorganic silica matrix by sol-gel processing. Sub-Micron films of this material can be prepared by spin-coating, and thicker films can be prepared by casting or by spinning multiple layers. After curing at 150 °C, these films exhibit good chemical durability. The chromophores can be aligned by either corona or parallel-plate poling during the curing process. In this paper we will discuss the synthesis of the NLO compounds; sol-gel processing and thin-film preparation; optical, thermal, and chemical properties of the films; and the results of both corona and parallel-plate poling experiments.
Optical Interconnect: Fully Embedded Etched Passive And Active Polyimide Waveguides And Devices
Authors: Fujimoto Harry H. , Das Siddhartha , Valley John F. , Stiller Marc , Dries Larry , Girton Dexter , Eck Tim Van , Ermer Susan , Binkley Ed S. , Nurse Jim C. , Kenney John T.
Published: March 2011

Electro-optic polymers are of great interest for inserting photonic elements into electronic systems. Recently Much progress has been made in both materials and processing. These polymers must have low optical loss, high mechanical integrity, low processing cost, and high temperature stability. In the first part of our talk, we present our work to produce etched single mode buried channel waveguides in an all polymide system. We have chosen polyimide because of its high temperature stability. Optical losses and waveguide characteristics are described as a function of waveguide width and index ofrefraction difference between core and cladding.

Mach Zehnder Modulators fabricated using a DCM-polymide core are also described The waveguide cores are etched and fully embedded in a polyimide cladding. The active arms of the modulator are poled using parallel plate poling. The electro-optic properties of the Mach Zehnder are described operating at 830nm. Photobleached DCM waveguides are also describe. A new high temperature chromophore is presented.
Photorefractivity And Photoisomerization In Azo-Dye-Doped Polymers
Authors: Kippelen B. , Sandalphon  , Meerholz K. , Volodin B. , Lyon S. R. , Padias A. B. , Hall H. K. , Peyghambarian N.
Published: March 2011

The photorefractive properties of photoconducting polymers doped with nonlinear azo dyes are investigated by means of polarization and field-dependent four-wave Mixing experiments. The nonlocal response of the photorefractive effect is shown by two-beam coupling experiments. High diffraction efficiencies (> 5%) and net coupling gain (6 cm-l) are demonstrated at low power with a semiconductor laser diode in 105 μm films. Under some conditions, gratings due to photoisomerization of the azo dye molecules are also present and their properties are discussed.
Phosphorus-Containing Poly (Arylene Ether)s as Second Order Nonlinear Optical Materials
Authors: Priddy Duane B. , Stacey Fu C. Y. , Pickering Timothy L. , Lackritz Hilary S. , Mcgrath James E.
Published: March 2011

Poly (arylene ether)s can be designed to be amorphous, optically clear materials with excellent hydrolytic and thermal stability as well as good electrical, Mechanical and fire resistant properties. As a result, the use of these macromolecules in second order nonlinear optical (NLO) applications are being investigated. Typically, polymeric systems with doped chromophores result in a signigicant decrease in Tg. Methods were investigated to functionalize the polymer backbone with NLO chromophores, resulting in increased Tg.
Characterizing The Distribution Of Space Charge In Poled Polymer Films
Authors: Haber Kenneth S. , Ostrowski Mark H. , O'Sickey Matthew J. , Lackritz Hilary S.
Published: March 2011

Much effort has been put into improving the temporal stability of electric field-induced chromophore alignment in molecularly doped or functionalized polymers for second order nonlinear optical device applications. Characterization of the alignment decay in electric field-poled films is complicated by charge injection during poling. In order to optimize poling schemes and to accurately determine the orientational mobility of the chromophores it is necessary to develop methods to measure the spatial extent and time-dependence of any residual fields in the polymer films. Such Measurements will also be important for the development of polymer-based electro-optic devices, and in fact for any guided wave application in these materials since the residual field may induce a spatial dependence in the refractive index.
Processable Cross-Linked Polymers for Nonlinear Optical Applications
Authors: Ellen Harelstad R. , Francis Cecil V. , Leung Peter C. , Korkowski Paul F. , White Kenneth M. , Cross Elisa M. , Kitipichai Prakob
Published: March 2011

Novel difunctional barbituric acid methine dyes have been synthesized for nonlinear optical applications. These Molecules have been reacted with Multi-functional isocyanates resulting in cross-linked polyurethanes. The thermal stability of the dye in crystalline form as well as dissolved in poly (Methylmethacrylate) was studied. Results suggest that although the dye crystals were thermally stable to 300 °C, when dissolved in a polymer the stability was markedly lower.
Bipolaron Formation and Nonlinear Optical Properties in Bis-Thienyl Polyenes
Authors: Spangler C. W. , He M. Q. , Laquindanum J. , Dalton L. , Tang N. , Partanen J. , Hellwarth R.
Published: March 2011

Bipolaron-like dications have been produced in both diphenyl and bis-thienyl polyenes by oxidative doping in solution. However, until now spectroscopie studies of the charge state generation beyond the hexaene have been precluded due to lack of solubility and processibility. We have now been able to extend these studies to the decaene by incorporating solubilizing substituents on the thienyl end caps. For the neutral species, degenerate four wave Mixing (DFWM) studies indicate that χ(3) is still increasing as a function of conjugation length. Introduction of mesomerically interactive RS groups on the thiophene rings further increases both solubility and optical nonlinearity.
Liquid Crystalline Polymers In Nematic Solvents
Authors: Williams D.R.M. , Halperin A.
Published: March 2011

We present a theoretical study of liquid crystalline polymers in nematic solvents. We focus on the following topics: (i) Rod-like chains confined between plates, (ii) Flexible chains in a slit (iii) Nematic brushes and double-brushes (iv) Anchoring transitions. Confined and grafted chains in nematic solvents can exhibit a variety of interesting effects, including quasi-piezoelectricity and a lowering of the critical voltage for the Fréedericksz transition.
Characterization Of Physically Vapor Deposited Af2400 Thin Films
Authors: Chow R. , Spragge M. K. , Loomis G. E. , Rainer F. , Ward R. L. , Thomas I. M. , Kozlowski M. R.
Published: March 2011

Anti-reflective optical coatings made with Teflon AF2400 had the highest laser damage thresholds recorded for physical vapor deposited coatings at the Lawrence Livermore National Laboratory damage facility. Physical vapor deposited layers of Teflon AF2400, a perfluorinated amorphous polymer, Maintained the bulk optical properties of a high transmittance from 200 nm to 1200 nm, and a low refractive index. In addition, the refractive index can be intentionally reduced by control of two common deposition parameters, deposition rate and substrate temperature. Scanning electron microscopy and nuclear magnetic resonance observations indicated that morphological changes caused the variations in the refractive index rather than compositional changes. The coatings adhered to fused silica and silicon wafers under normal laboratory handling conditions.
Energy Transfer And Emission Processes In Sol-Gel Materials Doped With Europium (III) Complexes
Authors: Wang Xiao-Jun , Matthews Lowell R. , Knobbet E. T.
Published: March 2011

Optical emission behavior in sol-gel-derived Materials doped with tris (4,4,4-trifluoro-l- (2′-thienyl) -l,3-butanedionato-O,O′)europium (III), Eu (ttfa)3, has been investigated by exciting the electronic levels of both europium (III) and the β-diketonate ligand (ttfa-). Energy transfer processes between the ttfa− ligands and europium (III) have been studied by time-resolved luminescence spectroscopy. The dynamic processes were compared in three sol-gel-derived host Matrices (silica, an acrylate ORMOSIL, and an epoxide ORMOSIL). Concentration dependence of the energy transfer rates was also studied.
Even Parity States in Ppv, Polythiophene and Polysilanes
Authors: Guo F. , Chandross M. , Mazumdar S.
Published: March 2011

Two photon absorptions (TPA) in conjugated polymers with large bond alternation are reinterpreted. TPA to the 2Ag in long chains should be tiny due to cancellation effects, and therefore the observed strong, narrow TPA is to a higher even parity state. We also present the first theoretical evidence for bound biexcitons, and explain recent photoinduced absorption data.
Langmuir-Blodgett Film Waveguide with The Nonlinearity Inversion in The Thickness Direction
Authors: Asai Nobutoshi , Fujiwara Ichiro , Tamada Hitoshi , Seto Jun'etsu
Published: March 2011

A second order nonlinear optical susceptibility inversion structure in the thickness direction (NIST) is proposed for enhancing the efficiency of Cerenkov radiation type phase matched second harmonic generation (CRPM-SHG). With the aid of the coupled-mode theory, it is analyzed that the efficiency is enhanced by 50 to 100 times by introducing the NIST structure to a waveguiding layer made of a 2-docosylamino-5-nitropyridine (DCANP) Langmuir-Blodgett (LB) film, and that the optical conditions for the most efficient CRPM-SHG are equivalent to those for guided mode SHG at the cutoff points of the modes. Several fabrication methods are possible for NIST waveguides. For the first time, a NIST waveguide has been fabricated using a DCANP-LB film by employing a novel and simple technique in which the substrate inversion is carried out during the dipping process. The inversion in nonlinearity was confirmed using the maker fringe method and polarized absorption spectra. A NIST planar waveguide of 260 Monolayers of DCANP (570 nm thick) was fabricated. Intense CRPM-SHG was observed from the waveguide when a YAG laser was coupled into it. The intensity was 20 to 30 times larger than that of a conventional waveguide of the same thickness.
Influence of Crystalline Structure on Performance of Thin Film Transistors
Authors: Celler G. K. , Ng K. K. , Trimble L. E. , Povilonis E. I.
Published: March 2011

We have developed a procedure to optimize electron mobility and leakage currents in MOSFETs fabricated in laser recrystallized polysilicon films on SiO2. A shaped laser beam was used to obtain grain boundaries aligned with the current flow in MOS transistors. To suppress grain boundary diffusion, rapid thermal annealing replaced all high temperature processing steps subsequent to source and drain implantation. By combining these two approaches, functional transistors as short as 1.5 μm were obtained, and also 2 μm-channel 19-stage ring oscillators with 115 psec/stage propagation delay.
Electrical Characterization of Laser/Energy-Beam Recrystallized Thin Film Silicon-On-Insulator (SOI)
Authors: Lee El-Hang , Ruprecht D. J.
Published: March 2011

Spreading resistance has been measured for various types of grain boundaries formed on graphite heater recrystallized SOI samples (G-SOI) or laser strip beam-recrystallized SOI samples (L-SOI) in order to identify the characteristic relation between the morphological/structural variation of the boundary defects and their electrical transport properties. In general, the resistance values across L-SOI sub-boundaries are higher than those across G-SOI sub-boundaries. TEM analyses reveal evidences of higher degree of crystallographic mismatch (up to 10°) in L-SOI sub-boundaries than that (1 – 2°) in G-SOI sub-boundaries. The measurement also revealed the evidences of counter-doping near the seed areas where the epitaxial growth initiated.
3-Dimensional Integration Fabricated by Using Seeded Lateral Epitaxial Film on SiO2
Authors: Sasaki N. , Iwai T. , Kawamura S. , Mukai R. , Wada K. , Nakano M.
Published: March 2011

Seeded lateral epitaxial laser-recrystallization of silicon film on SiO2 is applied to fabricate 3-dimensional (3-D) integrations: 3-D CMOS 7-stage ring oscillators. Top p-channel Si-gate SOI MOSFET's are fabricated in the seeded recrystallized silicon directly above bottom n-channel Si-gate bulk MOSFET's with insulator in between. The recrystallized silicon at the seed region can be utilized for buried contact to interconnect bottom and top MOSFET's. At the arsenic implantation step to fabricate source and drain of the bottom MOSFET's, ions are not implanted into the seed region to prevent heavy doping and crystal disorder there; otherwise the dopant diffuses laterally and residual crystal disorder disturbs the epitaxial recrystallization. After the laser-recrystallization, the seed region is implanted with phosphorus to interconnect the top and bottom MOSFET's.

The Ar+ laser irradiation is performed with a 10 W power, a 50 μm spot size, a 13 cm/s scanning speed and a 13 μm step at 400 °C in air. Propagation delay of 460 psec is obtained for the seven stage 3-D CMOS ring oscillator at a power supply voltage of 17 V for a channel length of 3 μm and a channel width of 18 μm. In the seeded SOI films, grain boundary generation and crystal orientation can be controlled.
Polysilicon Grain Growth by Rapid Isothermal Annealing
Authors: Pinizzotto R. F. , Clark F. Y. , Malhi S. D. S. , Shah R. R.
Published: March 2011

one method of reducing the area occupied by a RAM cell is to stack the p- and n-channel devices on top of one another. This “stacked CMOS” structure is a first step towards three dimensional integration. The simplest approach is to use polysilicon as the substrate for the top transistors. This paper describes the results of grain growth studies of samples annealed by rapid isothermal annealing. The temperature varied from 1100 to 1400°C and the anneal time varied from 10 to 480 seconds. TEM was used to examine the microstructure of the material. The grain growth was found to be film thickness limited, i.e. the final grain size was approximately the same as the initial film thickness. As a result, the kinetics of grain growth cannot be described by a simple logarithmic time law. There also is a velocity dependent drag contribution to the growth kinetics that implies impurities play an important role. The interlevel oxide thickness affects grain growth. Thicker oxides lead to faster growth, probably by reducing the heat flow to the silicon substrate. A capping layer was found to have no effect on the grain size. The above results indicate that it is possible to obtain large grains in short times using isothermal annealing. This process may be useful for fabricating stacked polysilicon layers in three-dimensional integrated circuits.
Effects of Grain Boundaries on the Current-Voltage Characteristics of SOI Mosfets
Authors: Fossum Jerry G. , Ortiz-Conde Adelmo
Published: March 2011

A physical model that describes the steady-state current-voltage characteristics of field-effect transistors (MOSFETs) fabricated in (poly)silicon-on-insulator (SOI) is described. The model predicts that a single high-angle grain boundary, especially one traversing the channel near the drain, can control the conduction properties of the MOSFET for all (weak-to-strong) inversion conditions in all (linear-to-saturation) regions of operation.
Impurities in Bulk A-Si:H, Silicon Nitride, and at the a-Si:H/Silicon Nitride Interface
Authors: Tsai C. C. , Thompson M. J. , Tuan H. C.
Published: March 2011

Major impurities in a-Si:H are O, C and N, while those in silicon nitride are H, O, C, F, Cl and excess Si. We show that a large reduction in both contaminant impurities and cross contamination achieved in the UHV plasma deposition system yields high purity a-Si:H. The impurity at the a-Si:H/nitride interface is observed to depend strongly on the order of deposition. There is a large amount of nitrogen carried over into a-Si:H when the a-Si:H is deposited after the nitride, Such a compositional asymmetry is likely to lead to an asymmetry in interface characteristics.
The Current Status of Silicon-On-Sapphire and other Heteroepitaxial Silicon-On-Insulator Technologies
Authors: Golecki I.
Published: March 2011

The present understanding of the properties of thin (≤0.6 μm) heteroepitaxial Si films grown on single-crystal bulk and thin film insulators is reviewed. Three areas are covered: (a) as-deposited Si films on bulk insulators, with particular emphasis on sapphire and cubic zirconia (b) post-growth processing methods to reduce the defect concentration and compressive strain in such Si films and (c) the growth and properties of monocrystalline insulating films on bulk Si and of Si on such films. The desired characteristics of the insulating material are given, and it is shown that the mismatch in thermal expansion coefficients between the insulator and Si dominates the properties of heteroepitaxial Si films. Present and future areas of application for Si-on-insulator technologies are briefly described, and directions for further studies are proposed.
Attempts to Apply Thin Film Transistors to Electroluminescent Displays
Authors: Miller M. Robert
Published: March 2011

The objectives of the two programs described here were to develop fabrication processes for flat panel displays using an active matrix of thin film transistors (TFT) behind an electroluminescent (EL) display medium. The programs were carried out under ERADCOM contracts DAAB07-76-C-0027 with Westinghouse R&D Center and DAAB-07-77-C-0583 with Aerojet Electrosystems Company. The huge amount of information about the processes and technology generated through the efforts of capable and dedicated people who worked on these programs was, in spite of everything, not enough to achieve the stated objectives. The fabrication processes developed did not result in repeatable, reliable display devices. The solutions applied to one set of problems tended to uncover new problems previously unseen, but this continual problem solving process probably generated more information about the technology than results from many programs in which the goals are achieved. The improved understanding of TFT processes and applicability is the subject of this report.
Characterization of CMOS Devices in 0.5-μm Silicon-On-Sapphire Films Modified by Solid Phase Epitaxy and Regrowth (Spear)
Authors: Vasudev P.K. , Mayer D.C.
Published: March 2011

Complementary Metal-Oxide-Semiconductor (CMOS) devices and circuits with minimum feature sizes of about 1 μm were fabricated in 0.5-μm-thick epitaxial Silicon-On-Sapphire (SOS) films. The films were modified by ion implantation and subsequent solid phase recrystallization processes which reduced the total microtwin concentrations in the Si layers by more than a hundredfold, while increasing electron and hole channel mobilities between 40 to 50%. Leakage currents were reduced by over 2 orders of magnitude, while drive currents and subthreshold slopes showed significant improvements over as–grown SOS films. Propagation delays of less than 80 psec were obtained for CMOS/SOS inverters with Leff = 0.6 μm.