bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving Electrotextile Wearability Using Stiffness Testing Methods
Authors: Slade Jeremiah , Wilson Patricia , Farrell Brian , Teverovsky Justyna , Thomson Douglas , Bowman Jeremy , Agpaoa-Kraus Marty , Horowitz Wendy , Tierney Edward , Offray C. M. , Winterhalter Carole 
Published: April 2011

ABSTRACTThe ability to integrate electrical functionality into textile garments is becoming increasingly desired both on the battlefield and in the work environment. In order to accomplish this, the issue of compatibility of mechanical properties between dissimilar materials needs to be addressed. Textiles are typically selected for comfort while electrical materials are chosen for superior electrical properties with secondary consideration given to properties such as flexibility. As a result many attempts to integrate electrical functionality into textiles result in stiff, unwieldy garments that have difficulty gaining user acceptance.Part of the electrotextile work done at Foster-Miller has focused on the integration of these dissimilar materials in a manner that does not degrade the wearability of the garment. Our work has included the development of textile cables that carry power and data using both electrical and optical media. In order to assess the wearability of these cables a method was needed of testing their stiffness. Several methods of measuring textile stiffness existed but did not address the many issues and material characteristics unique to conductive textiles.
Low-Voltage Organic Thin Film Transistors on Flexible Plastic Substrates with Anodized Ta2O5 Gate Insulators
Authors: Inoue Youji , Fujisaki Yoshihide , Iino Yoshiki , Kikuchi Hiroshi , Tokito Shizuo , Sato Fumio 
Published: April 2011

ABSTRACTOrganic thin film transistors (OTFTs) that operate at low voltage were fabricated using a tantalum oxide (Ta2O5) gate insulator on plastic substrates. The Ta2O5 insulator was prepared by anodizing a Ta gate electrode. The high dielectric constant of the Ta2O5 enabled the OTFTs to operate at a lower voltage than those of previous devices. The OTFTs exhibited a high field-effect mobility of 0.35 - 0.51 cm2/Vs, and a current on/off ratio of 105-106 at gate voltages of less than 5 V. The threshold voltage of -1.1 V and the subthreshold slope of 0.2 V/decade were the best among those reported to date. We also demonstrated operation of a phosphorescent organic light-emitting device (OLED) with the OTFT operating at a low voltage.
Chemically Functional Semiconductor Nanocrystals: Electrochemistry and Self-Assembly on Surfaces
Authors: Hutchins Benjamin M. , Latham Andrew H. , Williams Mary Elizabeth 
Published: April 2011

ABSTRACTSemiconductor nanocrystals (i.e., Quantum Dots, QDs) exhibit size-dependent emission properties and have synthetically adjustable ligand shells, making them interesting materials for applications ranging from luminescent displays to biomolecular tags. In this paper, the electrochemical properties of two types of nanocrystal are studied with an emphasis on the effect of core/shell vs core structures. The band gap energy of CdSe particles, measured using optical spectroscopy, was shown to increase slightly with the application of a ZnSe shell, as expected based on the increased energy required to transfer an electron through the shell material. The electrochemically determined band gaps are overestimated in the case of CdSe/ZnSe core/shell nanoparticles, reflecting the band gap of the ZnSe shell. Finally, QDs were self-assembled onto gold surfaces by electrostatic and covalent attachment, and their presence confirmed by fluorescence spectroscopy. The high intensity of emitted light shows that the QDs can be self-assembly onto metallic surfaces, without energy transfer quenching of the luminescence.
Size and shape dependent level structure in CdSe quantum rods
Authors: Rothenberg Eli , Mokari Taleb , Banin Uri , Katz David , Wizansky Tommer , Millo Oded 
Published: April 2011

ABSTRACTOptical spectroscopy and Scanning Tunneling Microscopy are used to study the size and shape dependence of the electronic states in CdSe quantum rods. The quantum rods were grown using colloidal chemistry synthesis methods, with good control over size and size distribution. Samples having average rod dimensions ranging from 10 to 60 nm in length and 3.5 to 7 nm in diameter, with aspect ratios varying between 3 to 12, were investigated. Both optical (at 10 K) and tunneling (at 4.2 K, on single rods) spectra show that the level structure depends primarily on the rod diameter and not on length. With increasing diameter, the band gap and the excited state level spacings shifted to the red. The level structure is assigned using a multi-band effective-mass model, showing relatively good agreement with experiment. We shall also discuss the effect of single electron charging on the tunneling spectra, possibly reflecting the quantum rod level degeneracy.
Transport Properties of Superlattice Nanowires and Their Potential for Thermoelectric Applications
Authors: Lin Yu-Ming , Dresselhaus Mildred S. 
Published: April 2011

ABSTRACTA theoretical model for the electronic structure and transport properties of superlattice (SL) nanowires is presented, based on the electronic tunneling between quantum dots. Due to the periodic potential perturbation, SL nanowires exhibit unusual features in the electronic density of states that are absent in homogeneous nanowires. Transport property calculations of PbSe/PbS SL nanowires are presented, showing improved thermoelectric performance compared to homogeneous nanowires because of a lower lattice thermal conductivity and an enhanced Seebeck coefficient, indicating that SL nanowires are promising systems for thermoelectric applications.
Carrier Tunneling, Current Instabilities, and Negative Differential Conductivity in Nanocrystalline Silicon – Silicon Dioxide Superlattices
Authors: Kamenev B. V. , Grom G. F. , Lockwood D. J. , McCaffrey J. P. , Laikhtman B. , Tsybeskov L. 
Published: April 2011

ABSTRACTLow temperature measurements of differential conductivity in nanocrystalline Si – amorphous SiO2 superlattices surprisingly reveal a clear double-peak structure associated with tunneling via levels of light and heavy holes. Numerical simulations show not only detailed agreement with the experiment but also predict that the studied system has no stable solutions for carrier concentration higher than 1017 cm−3. According to this prediction, partial screening of the external electric field generates current instabilities and oscillations, and that is experimentally observed. The developed model also suggests that a more uniform electric field and stabilization of carrier transport at a higher level of carrier density can be achieved under transient carrier injection.
SiC-Like Phase and Room-Temperature Photoluminescence of Low-K SiOCH Films
Authors: Ligatchev V. , Wong Rusli T.K.S. , Liu B. , Ostrikov K. 
Published: April 2011

ABSTRACTCarbon-doped hydrogenated silicon oxide (SiOCH) low-k films have been prepared using 13.56 MHz discharge in trimethylsilane (3MS) - oxygen gas mixtures at 3, 4, and 5 Torr sustained with RF power densities 1.3 − 2.6 W/cm2. The atomic structure of the SiOCH films appears to be a mixture the amorphous SiO2-like and the partially polycrys-talline SiC-like phases. Results of the infra-red spectroscopy reflect the increment in the volume fraction of the SiC-like phase from 0.22 − 0.28 to 0.36 – 0.39 as the RF power increment.Steady-state near-UV laser-excited (364 nm wavelength, 40±2 mW) photoluminescence (PL) has been studied at room temperatures in the visible (1.8 eV – 3.1 eV) subrange of photon spectrum. Two main bands of the PL signal (at the photon energies of 2.5 – 2.6 eV and 2.8 − 2.9 eV) are observed. Intensities of the both bands are changed monotonically with RF power, whereas the bandwidth of ∼0.1 eV remains almost invariable. It is likely that the above lines are dumped by the non-radiative recombination involving E1-like centres in the amorphous-nanocrystalline SiC-like phases. Such explanation of the PL intensity dependences on the RF power density is supported by results of experimental studies of defect states spectrum in bandgap of the SiOCH films.
Functionalization of Porous Silicon with Alkenes and Alkynes via Carbocation-Mediated Hydrosilylation
Authors: Schmeltzer J. M. , Porter Lon A. , Stewart Michael P. , López Carmen M. , Buriak Jillian M. 
Published: April 2011

ABSTRACTEfforts to produce stable, derivatized porous silicon have yielded a number of chemical methods capable of functionalizing this interesting material with organic monolayers. Hydride-terminated porous silicon substrates react with alkenes and alkynes in the presence of dilute triphenylcarbenium salt solutions to respectively produce alkyl- and alkenyl-functionalized materials. Characterization by transmission FTIR and solid-state NMR suggests the formation of highly stable silicon-carbon bonds to yield covalently bound organic moieties. Porous silicon passivated in this fashion exhibits a greater resistance than that of the native material to chemical degradation, indicating that the organic functionalities may serve to sterically shield the nanocrystallites from nucleophiles. Hydrosilylation is proposed to proceed via hydride abstraction from the substrate followed by electrophilic attack by the subsequent species upon the alkene/alkyne, a mechanism previously hypothesized for the formation of stabilized β-silyl carbocations. The reaction is tolerant of a variety of substrate functional groups and native porous silicon surfaces but depends markedly upon the identity of the salt counteranion, among other solution parameters.
Imaging, Structural and Chemical Analysis of Silicon Nanowires
Authors: Barsotti R. J. , Fischer J. E. , Lee C. H. , Mahmood J. , Adu C. K. W. , Eklund P. C. 
Published: April 2011

ABSTRACTLaser ablation has been used to grow silicon nanowires with an average diameter of 6.7 nm ± 2.7 nm surrounded by an amorphous SiOx sheath of 1–2 nm. This paper reports the imaging, chemical and structural analysis of these wires. Due to the growth temperature and the presence of calcium impurities and trace oxygen, two distinct types of wires are found. They appear to grow by two different processes. One requires a metal catalyst, the other is catalyzed by oxygen.
Nano-Optics of Bismuth Nanowires
Authors: Black M. R. , Hagelstein P. L. , Dresselhaus M. S. 
Published: April 2011

ABSTRACTThe optical absorption from an indirect L-T point valence band transition in bismuth nanowires is simulated based on a surface sensitive term, which is very weak in bulk bismuth, but effectively couples the L and T point bands in bismuth nanowires. The experimental Fourier transform infrared absorption spectra in the energy range 0.08 to 0.5 eV are compared to theoretical simulations for absorption resulting from indirect interband transitions between subbands at the L point valence band to subbands at the T point valence band as the polarization, tellurium doping, and wire diameter are varied. The simulated absorption from this indirect transition reproduces many of the experimentally observed trends and allows us to conclude that the dominant feature in the experimental absorption spectra of Bi nanowires results from an indirect L-T point transition which is enhanced in Bi nanowires.
Particle Production in High Density Silane Plasma
Authors: Shen Z. , Kim T. , Kortshagen U. , McMurry P. H. , Campbell S. A. 
Published: April 2011

ABSTRACTTo understand the mechanisms of nanoparticle formation and its potential applications, we have investigated silicon particles formed in various gasses in an inductive coupled plasma (ICP) system and have measured their structural properties by electron microscopy. Particle generation in pure SiH4 and SiH4/H2 are reported. ICP silane plasmas are shown to be an interesting and versatile source of nanoparticles. Three regimes are mapped out: a regime of no observable particle growth at the lowest pressures, a regime of polydisperse and agglomerated particles at the highest pressures, and a regime yielding highly monodisperse particles at intermediate pressures. Conditions that generate these nonagglomerated, extremely monodisperse silicon particles are emphasized. For H2 dilutions less than 92%, the growth rate is almost independent of H2 partial pressure. Particle growth decreases steadily when the H2 dilution is increased further. TEM images, however, indicate that the addition of hydrogen decreases the particle density. At higher dilution ratios, polycrystalline particles are obtained. Under all other conditions the particles are amorphous. Reasons for this behavior are explored.
Ion Projection Direct-Structuring For Nanotechnology Applications
Authors: Loeschner Hans , Fantner Ernest J. , Korntner Regina , Platzgummer Elmar , Stengl Gerhard , Zeininger Michaela , Baglin J. E. E. , Berger Ruediger , Brünger Wilhelm H. , Dietzel Andreas , Baraton Marie-Isabelle , Merhari Lhadi 
Published: April 2011

ABSTRACTLarge-field ion-optics has been developed for reduction printing. Sub-100nm ion projection direct-structuring (IPDS) of patterned magnetic media discs has been demonstrated, extending over 17mm diameter exposure fields, in a single exposure. First results of IPDS patterning of nanocomposite resist material are presented. Information about a novel 200x reduction projection focused ion multi-beam (PROFIB) tool development is provided. Further IPDS nanotechnology applications are discussed.
Shape Variations and Control in Self-Assembled Metal Nanoclusters
Authors: Zubris M. , Solimando M. , Goldberg E. P. , Reich S. , Tannenbaum R. 
Published: April 2011

ABSTRACTThe selective interaction of metal clusters with various polymers constitutes the basis for the self-assembly approach to the synthesis of organic-inorganic hybrid materials, that leads to the control of particle size, geometry and dispersion gradient. Metal particles were synthesized by the thermal decomposition of an organometallic precursor, in this case, iron pentacarbonyl, in the presence of a polymer matrix. Under the conditions utilized for these reactions, the aggregation of the metallic clusters competed with the interactions between the growing metal fragments and the polymer matrix. The dominance of one reaction route as compared to the other, ultimately determined the equilibrium particle shape, size and distribution for each metal-polymer system. In this work, we attempted to analyze the formation of iron oxide nanoclusters in several structurally-distinct polymers, and developed a general mechanistic view to explain the characteristics of the polymer-metal oxide hybrid materials that were obtained.
Epitaxial Praseodymium Oxide: A New High-K Dielectric
Authors: Osten H. J. , Bugiel E. , Fissel A. 
Published: April 2011

ABSTRACTWe show results for molecular beam epitaxial (MBE) growth of praseodymium oxide on Si. On Si(100) oriented surfaces, crystalline Pr2O3 grows as (110)-domains, with two orthogonal in-plane orientations. Epitaxial overgrowth with Si could not been realized so far. We obtain perfect epitaxial growth of hexagonal Pr2O3 on Si(111). These layers can also be overgrown epitaxially with Si leading to novel tunnel structures. Crystalline Pr2O3 on Si(OOl) is a promising candidate for highly scaled gate insulators, displaying sufficiently high-K value of around 30, ultra-low leakage current density, good reliability, and high electrical breakdown voltage. The Pr2O3/Si(001) interface exhibits the symmetric band alignment, desired for applying such material in both n- and p-type devices. The valence band as well as the conduction band offset to Si is above 1 eV. The electron masses can be assumed to be very heavy in the oxide. This effect together with the suitable band offsets leads to the unusually low leakage currents found experimentally. Finally, the integration of crystalline Pr2O3 high-K gate dielectrics into a conventional CMOS process will be demonstrated.
Z-contrast Imaging and EELS of Dislocation Cores at the Si/GaAs Interface
Authors: Lopatin S. , Duscher G. , Pennycook S. J. , Chisholm M. F. 
Published: April 2011

ABSTRACTThe interface between silicon and epitaxial GaAs thin film grown by metalorganic chemical vapor deposition was studied using atomic-resolution Z-contrast imaging. Z-contrast imaging provides chemical composition information and allows direct interpretation of micrographs. Electron energy loss spectroscopy (EELS) yields correlation between structure and chemistry. Different types of dislocation were identified at the Si/GaAs interface. Atomic structure of non-reconstructed 90° dislocation (exhibiting a dangling bond) is refined by means of computer simulations based on functional density theory. EELS form planar Si/GaAs interface and dislocation cores obtained and analyzed.
Raman Scattering Study for Self-Organized Ge Quantum Dots Formed on Si Substrate
Authors: Yang T. R. , Dvoynenko M. M. , Feng Z. C. , Ferguson I. , Cheng H. H. 
Published: April 2011

ABSTRACTA Raman scattering study for self-organized Ge dots on Si substrate is presented. Raman signals from the Ge islands and Si substrate have been separated, by means of difference Raman spectroscopy technique. The wetting layer thickness and strain were estimated from the line width and the position of the peak. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. As explained, the strain is observed to decrease with an increase of the Ge island height and the wetting layer thickness.
A Boron Doped Amorphous Silicon Thin-Film Bolometer for Long Wavelength Detection
Authors: Heredia-J A. , Torres-J A. , Jaramillo-N A. , De la Hidalga-W F.J. , Landa-V. M. 
Published: April 2011

ABSTRACTThe fabrication of a bolometer for infrared detection using a boron doped amorphous silicon (a-Si-B:H) thin film is presented for the first time. This thin film (170 nm) was deposited on a silicon nitride membrane sustained by a frame made of micromachined crystalline silicon in order to improve the thermal isolation. Electrical connectivity to the element was achieved by means of aluminum contact pads. The resultant figures of merit, measured at room temperature, were: electrical conductivity of 1.513×10-3 (Ω-cm)-1, thermal coefficient of resistance of 3.4 %K-1, and the device is sensitive to temperature variations as small as 20 mK.
The Growth and Characterization of Zinc Oxide Thin Film on Fused Silica and SiO2/Si(100) Substrates
Authors: Jin C. , Tiwari A. , Porter H. , Park M. , Narayan J. 
Published: April 2011

ABSTRATCTIn this work, ZnO thin films were grown on amorphous fused silica and pre-oxidized silicon substrates by using pulsed laser deposition technique. X-ray diffraction patterns showed that the films were highly crystalline and c-axis oriented. The surface morphologies of the films were observed by using scanning electron microscope and optical microscope. Free exciton absorption was observed at room temperature for the film grown on fused silica substrate. The strong near-UV luminescence peaked at 380 nm were observed for all the films and was attributed to the phonon-related exciton emission. The effect of oxygen partial pressure on the luminescence intensity is also reported.
Characterization of AlInAsSb and AlGaInAsSb MBE-grown Digital Alloys
Authors: Vaughn Leslie G. , Ralph L. , Xu Huifang , Jiang Yingbing , Lester Luke F. 
Published: April 2011

ABSTRACTAs one of the few Type I band offset, antimony-based material systems available for 3.3 to 4.2 micron mid-infrared multiple quantum well lasers, AlInAsSb alloys have been used as barriers with InAsSb wells. Previously, AlxIn(1-x)AsySb(1-y) quaternary alloys have been grown by MBE as random alloys up to an aluminum fraction, x = 0.10 on GaSb substrates and x = 0.15 on InAs substrates. Random alloy growth of quaternary films with increased aluminum content, although beneficial to the devices, is limited by a miscibility gap. We have used a digital alloy technique to grow stable, single phase, GaSb lattice-matched, optically smooth quaternary alloys for aluminum fractions of 0.05 to 0.5, well into the miscibility gap. DCXRD results show FWHM of 0th order alloy peaks are within 1.5 to 2 times that of the highly crystalline GaSb substrates and have well defined thickness fringes corresponding to the total film thickness and the digital alloy period. TEM images show very well ordered alloys with characteristic ultrathin superlattice structure having smooth interfaces, very little strain and atomic ordering limited to that imposed by the digital alloy technique. Photoluminescence measurements are used to fit a model for bandgap prediction from known alloy compositions. Theoretical studies have predicted that the addition of a fifth element, gallium, may help suppress Auger recombination through its effects on the subband structure. So, gallium is added to the quaternary to produce a quinternary alloy lattice-matched to GaSb. These AlGaInAsSb alloys have DCXRD and TEM results similar to the quaternary. The stable, single-phase growth of these quinternary alloys across the composition range is promising for improving the operating characteristics of mid-IR lasers.
Silicon CMOS BEOL Compatible Optical Waveguide Micro-mirrors
Authors: Ponoth Shom , Agarwal Navnit , Persans Peter , Plawsky Joel 
Published: April 2011

ABSTRACTOptical waveguides are being explored for on-chip purposes to overcome the speed limitations of electrical interconnects. Passive optical components like waveguides and vertical outcouplers are important components in such schemes. In this study we fabricate planar waveguides with integrated vertical micro-mirrors using standard Back End of the Line silicon (BEOL) CMOS based processes. Around 1.6 μm of a hybrid alkoxy siloxane polymer with a refractive index of ∼ 1.50 at the intended wavelength of 830 nm is used as the core and plasma deposited silicon oxide with a refractive index of ∼ 1.46 is used as the cladding. The angular face in the polymer waveguide that would function as the mirror surface was fabricated by a pattern transfer method which involves transferring the angle in a template to the waveguide using anisotropic reactive ion etching. The sidewall angle realized in a positive resist on patterning was used as the angle template. Exposure and development conditions were adjusted for Shipley® S1813 photoresist to generate a sidewall angle of ∼ 65°. The anisotropic Reactive Ion Etching (RIE) was done using a CF4/O2 plasma chemistry. A gas composition of 50/50 CF4/O2 was chosen in order to minimize the etch related roughness of the polymer and the photoresist. The metallization of the mirror faces was done using a self-aligned maskless technique which ensures metal deposition only on the angular face and also eliminates a lithography step.
Photoluminescence in UHV/CVD tensile-strained Si type-II quantum wells on bulk crystal SiGe substrates
Authors: Sheng S.R. , Rowell N.L. , McAlister S.P. 
Published: April 2011

ABSTRACTNear band-edge photoluminescence (PL) in high-quality UHV/CVD tensile-strained Si type-II quantum wells (QWs) with varying well width grown on bulk crystal SiGe substrates has been studied. In contrast to the blue-shifts observed in the PL lines of Si1-xGex QWs on Si, the PL lines of Si QWs exhibit red-shifts with increasing excitation density. The PL from the SiGe substrate shows no such shift. The PL red-shifts decrease as the well width decreases, and are essentially independent of temperature up to 15K where a transition from bound exciton emission to higher energy free exciton emission occurs. The rapid thermal annealing (RTA) was found to improve the crystal quality of the samples. RTA enhances the integrated PL intensity, results in narrowing and blue-shifting of PL bands, and reduces the exponent in the excitation power dependence as well as the amount of red-shifting at a given excitation density. Possible mechanisms for the observed shifts to lower energies of the PL lines with excitation density were examined, including band bending, band-filling, and binding of excitons to impurities.