bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flexible Magnetics: Magnetic Lithography and Fabrication of Magnetic Masks on Thin Plastic Substrates
Authors: Bandić Z. Z. , Xu H. , Baglin J.E.E. , Albrecht T. R. 
Published: June 2019

AbstractFlexible magnetic lithography is a process qualitatively analogous to contact optical lithography which transfers information from a patterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist), and is interesting for applications in instantaneous parallel magnetic recording. The magnetic mask consists of patterned soft magnetic material (FeNiCo, FeCo) on a flexible plastic substrate, typically Polyethylene Teraphtalate (PET). When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. Flexible substrate of the magnetic mask o.ers superior compliance to magnetic media which is likely to have imperfect flatness and surface particulate contamination.Although magnetic in physical nature, flexible magnetics draws interesting parallels to flexible electronics, especially in challenges of fabrication of sub-micron patterns on thin flexible plastic substrates. We fabricated samples of sub-micron patterned FeCo and FeNiCo magnetic masks on PET substrates by using combined lamination/release process of PET films. Rigid substrates, typically silicon or quartz were initially laminated with PET films and processed using standard fabrication procedures. After completing magnetic mask device fabrication, PET films were released from the rigid substrates.We successfully transferred patterns from magnetic masks to hard disk CrPtCo-based magnetic media. The details of the method, including physics of the magnetic lithography pattern transfer, fabrication of the magnetic mask on flexible PET substrates, lamination and release of PET films, and magnetic force microscopy (MFM) images of the magnetic transition patterns are reported.
Characterizing the Modulus and Hardness of Photopatternable Silicone Compositions Using Depth Sensing Nanoindentation
Authors: Harkness Brian R. , Schalek Richard L. , Sarmah Satyen K. , Drzal Lawrence T. 
Published: June 2019

AbstractThe mechanical properties of two cured silicone monolithic specimens with targeted bulk moduli of 300 and 10 MPa have been evaluated by DMA and regionally by CSM nanoindentation. The results showed that the mechanical properties of the monolithic samples were heterogeneous, with the DMA and nanoindention results only in agreement at the midplane of cleaved bulk samples. The specimens showed a significantly higher modulus at the sample surfaces compared to the bulk. Thin films of the same silicones displayed a modulus closer to that of the bulk sample surface. The nanoindentation results of this study were reliable and consistent, and are being used to assess the effects of material and microelectronic device integration processes on the mechanical properties of a series of low modulus photopatternable silicone thin film dielectrics.
Electronic Energy Transfer from Excitons Confined in Silicon Nanocrystals to Molecular Oxygen
Authors: Gross E. , Kovalev D. , Künzner N. , Diener J. , Koch F. , Timoshenko V.Yu. , Fujii Minoru 
Published: June 2019

AbstractWe report on efficient electronic energy transfer from excitons confined in silicon (Si) nanocrystals to molecular oxygen (MO). The remarkable photosensitizing properties of Si nanocrystal assemblies result from a broad energy spectrum of photoexcited excitons, a long triplet exciton lifetime and a highly developed surface area. Quenching of photoluminescence (PL) of Si nanocrystals by MO physisorbed on their surface is found to be most efficient when the energy of excitons coincides with the triplet-singlet splitting energy of oxygen molecules. Spectroscopic analysis of the quenched PL spectrum evidences that energy transfer is accompanied by multi-phonon emission. From time-resolved measurements the characteristic time of energy transfer is found to be in the range of microseconds. The dependence of PL quenching efficiency on the surface termination of nanocrystals is consistent with short-range resonant electron exchange mechanism of energy transfer. The energy transfer to oxygen molecules in the gaseous phase at elevated temperatures is demonstrated.
Time-Resolved Gain Dynamics in Silicon Nanocrystals
Authors: Negro L. Dal , Cazzanelli M. , Daldosso N. , Pavesi L. , Priolo F. , Franzò G. , Pacifici D. , Iacona F. 
Published: June 2019

AbstractTime-resolved variable stripe length (VSL) experiments on a set of silicon nanocrystal waveguides obtained by plasma enhanced chemical vapor deposition (PECVD) have revealed a fast recombination dynamics (20 ns) related to population inversion under 6 ns optical pumping at 355 nm. Modal gain values about 10 cm-1 have been measured at 760 nm by VSL technique for the fast recombination component while optical losses about 15 cm-1 are measured for the integrated signal in the slow (lifetime of about 10 μs) recombination tail. Threshold behavior in the emission intensity together with a pumping length and pumping power dependence of both the intensity and the time duration of the fast recombination component has been observed. These results are explained within an effective four level model to describe the strong competition among different Auger processes and stimulated emission.
Thermo-Electric Performance of poly-Si0.7Ge0.3
Authors: Wijngaards D.D.L. , Wolffenbuttel R.F. 
Published: June 2019

AbstractThe performance of poly-Si0.7Ge0.3 as a thermo-electric material that is fully process compatible with IC fabrication in silicon been fully analyzed and characterized. The application is in on-chip thermal stabilization of a micromachined platform in silicon. A Seebeck coefficient α= -174 μV/K and a figure of merit z= 0.173 has been obtained for n-type material. Measurements indicate a cooling capability of 2.1 K below ambient temperature.
Electro-Optical Properties and Interfacial Charges in Polymer-Dispersed Liquid Crystal Devices
Authors: Ramsey Robert A. , Sharma Suresh C. , Henry Robert M. , Atman Jay B. 
Published: June 2019

AbstractPolymer-dispersed liquid crystal (PDLC) is a composite material that consists of sub micron-size droplets of liquid crystalline (lc) material dispersed in a polymer matrix. A device is usually assembled by sandwiching PDLC between ITO-coated glass plates. The electro optical properties of such a device can be controlled by the application of electric fields; the device acts as a “switch” for the transmission of light. The transmission of light through the device can be controlled between almost zero and 100% by applying ac electric fields. The dielectric properties of the lc and polymer, shape and size distribution of the lc droplets in the PDLC, amplitude and frequency of the applied electric field are among the important parameters for optimizing the performance of such a device. We have investigated the optical properties of PDLC devices fabricated by using several different phase-separation techniques and different lc/polymer materials. We present results for the switching characteristics of these devices as functions of applied electric fields and the size-distribution of the lc droplets. We also present results that reinforce the influence of the interfacial charges on the optical properties of the PDLC devices.
Alignment of Rigid-Rod Polypeptide Chains by Solvent Quenching
Authors: Wang Yuli , Chang Ying Chih 
Published: June 2019

AbstractWe introduce a simple “solvent quenching” approach to align the rigid-rod à-helical poly(α-benzyl-L-glutamate) (PBLG) chains in the surface-grafted monolayer. By sequentially treating with a good solvent and a poor solvent, a unidirectionally aligned PBLG monolayer with an average tilt angle as small as 3° is obtained.
In-situ electrical and spectroscopical techniques for the study of degradation mechanisms and life time prediction of organic based electronic material systems
Authors: Manca Jean , Goris Ludwig , Kesters Els , Lutsen Laurence , Martens Tom , Haenen Ken , Nesladek Milos , Sanna Ornella , Vanderzande Dirk , D'Haen Jan , Schepper Luc De 
Published: June 2019

AbstractIn order to tailor the synthesis of new robust organic materials for electronic applications and to guarantee the required life time for the emerging commercial plastic electronic applications it is of key importance to understand the underlying degradation mechanisms. Since plastic electronics is a rather young technology introducing new material systems, its reliability is characterized by new failure and degradation mechanisms, a relatively high amount of early failures and multi-modal failure distributions. To understand the mechanism responsible for a given failure or degradation mode, it is essential to study it separately, through appropriate test structures and test techniques. Powerful techniques for this purpose are a.o. analytical techniques (SEM, TEM, SPM,..), in-situ electrical measurement techniques and spectroscopical techniques (in-situ FTIR, in-situ UV-Vis, PDS). The benefits of these in-situ techniques in the reliability study of organic based electronics will be illustrated in this contribution.
The Effect of Doping on the Energy Distribution of Localized States and Carrier Transport in Disordered Organic Semiconductors
Authors: Arkhipov Vladimir I , Heremans Paul , Emelianova Evgenia V. , Adriaenssens Guy J. , Bässler Heinz 
Published: June 2019

AbstractDoping of a disordered organic semiconductor gives rise to additional energy disorder due to the Coulomb interaction between randomly distributed dopant ions and carriers localized in intrinsic hopping sites. Although the carrier density increases with increasing doping level the additional energy disorder can significantly reduce the carrier hopping mobility. At higher doping levels the filling of deep states takes over, which leads to steeply increasing mobility at high dopant concentrations.
Exciton Dissociation In Doped Conjugated Polymers
Authors: Arkhipov Vladimir I. , Heremans Paul , Emelianova Evgenia V. , Bässler Heinz 
Published: June 2019

AbstractA model of carrier photogeneration in doped conjugated polymers is formulated. The model suggests that dissociation of a relaxed exciton into a Coulombically bound geminate pair (GP) occurs at a charge transfer center that consists of a polymer chain and a nearby electron acceptor. Further dissociation of the GP into free carriers is facilitated either by the kinetic energy of the zero-point oscillation of the on-chain carrier at low dopant concentrations or by the interfacial potential barrier for geminate pair recombination in polymer/electron acceptor blends.
Thermocapillary Actuation of Liquids Using Patterned Microheater Arrays
Authors: Valentino Joseph P. , Darhuber Anton A. , Troian Sandra M. , Wagner Sigurd 
Published: June 2019

AbstractWe demonstrate a microfluidic actuation technique capable of directing nanoliter liquid samples on the surface of a glass substrate through the use of both electronically addressable heater arrays and chemical patterning. Pathways for liquid movement are delineated by the arrangement of microheaters, which also provide the thermocapillary actuating force. The drops are confined to these pathways by a selectively deposited fluorinated monolayer, which defines the channel edges. Operating voltages in the range of 2-3 V is used to move, split, and trap liquids. This fluid transportation technique enables direct access to liquid samples for handling and diagnostic purposes and offers a low power alternative to existing microfluidic systems.
ATRP Synthesis and Characterization of μ,αω-allyl-terminated Macromonomers as Precursors for End-linked Gels and Hydrogels
Authors: Vojtova Lucy , Turro Nicholas J. , Koberstein Jeffrey T. 
Published: June 2019

AbstractSynthesis of α,ω-allyl-terminated telechelic macromonomers based on poly(tert-butyl methacrylate) (poly(t-BMA)) and poly(methacrylic acid) (poly(MAA)) was studied with the aim of preparing end-linked gels and hydrogels. Low molecular weight α-allyl-terminated poly(t-BMA) macromonomers with narrow polydispersities (Mw/Mn = 1.16) were synthesized via controlled atom transfer radical polymerization (ATRP) using a Cu(I)Br/N,N,N',N',N',N'-hexamethyltriethylenetetraamine catalyst system in conjunction with an allyl-2-bromoisobutyrate as the functional initiator. The polymerizations exhibited a linear increase of molecular weight in direct proportion to the monomer conversion and first-order kinetics with respect to monomer concentration. No significant difference was found between using polar or non-polar solvents (tetrahydrofuran or benzene, respectively). Optimization of reaction conditions to obtain the highest degree of active terminal bromine is discussed. Quenching the ATRP reaction with allyltributyltin yielded α,ω-allyl-terminated poly(t-BMA) macromonomers by replacing the terminal bromine with ω-allyl functional group. Poly(MAA) macromonomers were prepared by deprotection of the tert-butyl group from α,ω-allyl-terminated poly(t-BMA) macromonomers using concentrated trifluoroacetic acid at room temperature. Successful synthetic steps were confirmed by 1H NMR, FT-IR and MALDI-TOF MS analyses. The α,ω-allyl-terminated macromonomers were proven to be candidates for further polymerization by forming end-linked, non-soluble gels.
From the Spider to the Web: Biomimetic Processing of Protein Polymers and Collagen
Authors: Stephens Jean S. , Rabolt John F. , Fahnestock Stephen R. , Chase D. Bruce 
Published: June 2019

AbstractThe use of electrostatic forces to shape materials processed from solution provides exciting opportunities to enhance material properties by creating new structures and morphologies during processing. In this context we report the formation of nanoscale webs composed of interconnected electrospun polymer fibrils. These nanowebs have been formed from synthetic spider silk, collagen, and denatured collagen when they are electrospun from various concentrations of formic acid. These nanowebs have been characterized by field emission scanning electron microscopy (FESEM) in order to characterize their morphology and measure their surface areas.
Spray Drying FunctionalizedMesostructured Colloids
Authors: Alberius Peter , Andersson Nina , Bergström Lennart 
Published: June 2019

AbstractAn industrially viable production method is a prerequisite for the commercialization of templated mesostructured materials, e.g. as carriers of various functionalities in coatings, in the coatings of ink jet paper and liquid chromatography. A small pilot plant was constructed for the continuous production of well ordered mesostructured materials (>10g/h) that can easily be scaled to an industrial process. The silica colloids have a well controlled internal mesostructure and are spherical with a mean diameter of 1-5μm. The mesoscopic pores in the calcined materials are accessible to relatively large molecules; up to 25 % (by weight) of the cationic dye Janus Green B could be adsorbed from an aqueous solution. We have also demonstrated how optically functional silica colloids could be prepared in a one-pot synthesis by introducing different dyes into the precursor solution.
Temperature Dependence of the Self-Assembled Styrene Based Random Ionomers in Aqueous Solution
Authors: Oh Sung-Hwa , Song Ju-Myung , Kim Joon-Seop , Oh Hyang-Rim , Yu Jeong-A 
Published: June 2019

AbstractSolution behaviors of poly(styrene-co-sodium methacrylate) were studied by fluorescence spectroscopic methods using pyrene as a probe. The mol% of methacrylate was in the range 3.6–9.4. Water and N,N-dimethylforamide(DMF) mixture was used as a solvent (DMF/water = 0.2 mol %). The critical micelle (or aggregation) concentrations of ionomers and the partition coefficients of pyrene were obtained the temperature range 10–80°C. At room temperature, the values of CMCs (or CACs) were in the range 4.7 ×10-6 5.3 ×10-6 g/mL and we could not find any notable effect of the content of ionic repeat units within the experimental errors. Unlike CMCs, as the ion content increased, partitioning of pyrene between the hydrophobic aggregates and an aqueous media decreased from 1.5 ×105 to 9.4 ×104. As the temperature increased from 10 to 80 °C, the values of CMCs increased less than one order of magnitude. While, the partition coefficients of pyrene decreased one order of magnitude and the effect of the ion content became negligible.
Structural and Compositional Evolution of Self-Assembled Germanium Islands on Silicon (001) During High Growth Rate LPCVD
Authors: Dilliway Gabriela D.M. , Cowern Nicholas E.B. , Jeynes Chris , O'Reilly Lisa , McNally Patrick J. , Bagnall Darren M. 
Published: June 2019

AbstractUnderstanding the process of self-organization of Ge nanostructures on Si with controlled size distribution is a key requirement for their application to devices. In this study, we investigate the temporal evolution of self-assembled islands during the low pressure chemical vapour deposition (LPCVD) of Ge on Si at 650°C using high growth rates (6–9 nm/min). The islands were characterized by atomic force microscopy, transmission electron microscopy, Rutherford backscattering spectrometry and micro-Raman spectroscopy. We found that the first nanostructures to assemble were small islands, with a narrow size distribution, typical of the ‘lens-shaped’ structures reported in previous studies. Next to form were a population of larger ‘lens-shaped’ islands with a similar surface density to that of the small islands, but with broad height and width distributions. These islands differ from the pyramid-shaped islands previously reported for a similar size range. On further Ge deposition, the population evolves into one of large square-based truncated pyramids with a very narrow size distribution. Such pyramidal structures were previously reported at smaller sizes. Furthermore, we see no evidence of the multifaceted domes previously reported in this size range. The small ‘lens-shaped’ islands appear to be strained, whilst some of the intermediate-sized islands and all the large truncated pyramids contain misfit strain relaxation induced defects. Additionally, in the both the intermediate size ‘lens-shaped’ islands and in the large size truncated pyramidal islands, there is evidence of Si-Ge strain-induced alloying, more significant in the first than in the latter. Our observation of ‘lens shaped’ islands and truncated pyramids at larger sizes than are normally observed, suggests a kinetically driven process that delays the evolution of energetically favourable island structures until larger island sizes are reached.
ESR Study of Electrochemically Doped Chalcogenide Nanotubes
Authors: Arcon Denis , Zorko Andrej , Cevc Pavel , Mrzel Ales , Remskar Maja , Mihailovic Dragan , Dominko Robert , Gaberscek Miran 
Published: June 2019

AbstractElectrochemical activity of differently pretreated single-wall subnanometer-diameter molybdenum disulfide tubes (nMoS2) was tested and compared with layered MoS2 material. In as prepared and de-iodized nMoS2 samples a significant increase in the charge capacity has been found compared to the one measured in dispersed nMoS2 or layered MoS2. Enhanced electrochemical activity has been attributed to a particular one-dimensional topology of nanotubes bundles. Electrochemically doped samples were then studied with X-band ESR. While undoped nMoS2 show no X-band ESR signal between room temperature and 4 K we found in heavily doped nMoS2 samples two distinct ESR components: a narrow component with a linewidth of few Guass and a broad component with a linewidth of more than 800 G. The broad ESR component is characteristic of Mo d-orbital-derived band. The temperature dependence of the ESR spin susceptibility and the linewidth of the broad ESR component can be discussed either in terms of conducting electrons coupled to defects or in terms of random-exchange Mo Heisenberg chain model.
Optimal Annealing Conditions of InGaAs Films for Selective Area Epitaxy of Quantum Dots by Indium Segregation
Authors: Yeoh Terence S. , Swint Reuel B. , Elarde Victor C. , Coleman James J. 
Published: June 2019

AbstractThe surface of strained InGaAs films on GaAs for selective regrowth of InAs nanostructures is investigated by atomic force microscopy and Rutherford backscattering. Various InxGa1-xAs films were annealed at temperatures between 400°C - 800°C. Significant indium desorption was found to occur at temperatures above 550°C.
Electron Microscopy Study of Submicron Size Antiferromagnetic KMnF3 Nanoparticles and Their Self-assembly
Authors: Anderson Jeffrey , Garcia Rubi , Zhou Weilie L. 
Published: June 2019

AbstractSubmicron KMnF3 cubic and spherical nanoparticles were synthesized using the reverse micelle method. The nanostructures of the nanocrystals were studied by field emission electron microscopy and transmission electron microscopy. KMnF3 nanocrystals synthesized at room temperature started with cubic submicron particles (∼100 nm) and consisted of KMnF3 nanocrystallites (10-15 nm). As the reaction continued, the nanocrystals fused together and transformed into perfect cubic nanocrystals. Spherical beads composed of KMnF3 nanocrystallites were observed at low temperature synthesis. As the reaction continued, the spherical particles grew larger, however, no characteristic cubic shape of KMnF3 nanoparticles were observed. Even as they grew larger, there was no evidence of homogeneous crystal morphology as seen in the room temperature samples. Cubic shape KMnF3 nanocrystals were self-assembled into large area self-assembling patterns.
Parallel Bias-Enhanced Sulfur-Assisted Chemical Vapor Deposition of Nanocrystalline Diamond Films
Authors: Jesùs Joel De , Gonzàlez Juan A. , Ortiz Oscar O. , Weiner Brad R. , Morell Gerardo 
Published: June 2019

AbstractThe transformations induced by the application of a continuous bias voltage parallel to the growing surface during the sulfur-assisted hot-filament chemical vapor deposition (HFCVD) of nanocrystalline diamond (n-D) films were investigated by Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The films were deposited on molybdenum substrates using CH4, H2 and H2S. Bias voltages in the range of 0 – 800 VDC were applied parallel to the substrate surface continuously during deposition. The study revealed a significant improvement in the films' density and a lowering in the defect density of the nanocrystalline diamond structure for parallel bias (PB) voltages above 400V. These high PB conditions cause the preferential removal of electrons from the gaseous environment, thus leading to the net accumulation of positive species in the volume above the growing film, which enhances the secondary nucleation. The nanoscale carbon nuclei self-assemble into carbon nano-clusters with diameters in the range of tens of nanometers, which contain diamond (sp3-bonded C) in their cores and graphitic (sp2-bonded C) enclosures. Hence, the observed improvement in film density and in atomic arrangement appears to be connected to the enhanced presence of positively charged ionic species, consistent with models which propose that positively charged carbon species are the crucial precursors for CVD diamond film growth.