National Library of Energy BETA

Sample records for doping dual-gated bilayer

  1. Development of Dual-Gated Bilayer Graphene Device Structures. (Conference)

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing BacteriaConnectlaser-solidSwitchgrass and Miscanthus x| SciTech Connect

  2. Electrical Modulation of Ion Concentration in Dual-Gated Nanochannels Yang Liu, Qiushi Ran, and Robert W. Dutton

    E-Print Network [OSTI]

    Liu, Yang

    Electrical Modulation of Ion Concentration in Dual-Gated Nanochannels Yang Liu, Qiushi Ran simulations demonstrate the operating principles of using electrical biases in dual-gated nano potential applications range from fuel cells [11] to desalination [12]. Nevertheless, in contrast

  3. Bilayer Graphene Photon Detector J. Y. Yan, M.-H. Kim, J. A. Elle, A. B. Sushkov, G. S. Jenkins, H. M. Milchberg

    E-Print Network [OSTI]

    Bernstein, Joseph B.

    Bilayer Graphene Photon Detector J. Y. Yan, M.-H. Kim, J. A. Elle, A. B. Sushkov, G. S. Jenkins, H in graphene suggests that "hot electrons" created by incident light can provide the basis for a fast graphene in a "dual-gated" structure. This new "bolometer" has ultralow noise, besting existing detectors

  4. Bi-layer non-doped small-molecular white organic light-emitting diodes with high colour This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Bi-layer non-doped small-molecular white organic light-emitting diodes with high colour stability and conditions apply. View the table of contents for this issue, or go to the journal homepage for more Home-layer non-doped small-molecular white organic light-emitting diodes with high colour stability Shuming Chen1

  5. Optical spectroscopy of bilayer Baisong Geng

    E-Print Network [OSTI]

    Zettl, Alex

    -gate bilayer graphene device, we were able to control the carrier doping and a semiconductor bandgap the inversion symmetry between the top and bottom graphene layers. This semiconductor bandgap canOptical spectroscopy of bilayer graphene Baisong Geng 1,2 , Jason Horng 1 , Yuanbo Zhang 1

  6. Charge noise analysis of metal oxide semiconductor dual-gate Si/SiGe quantum point contacts

    SciTech Connect (OSTI)

    Kamioka, J.; Oda, S.; Kodera, T.; Takeda, K.; Obata, T.; Tarucha, S.

    2014-05-28

    The frequency dependence of conductance noise through a gate-defined quantum point contact fabricated on a Si/SiGe modulation doped wafer is characterized. The 1/f{sup 2} noise, which is characteristic of random telegraph noise, is reduced by application of a negative bias on the global top gate to reduce the local gate voltage. Direct leakage from the large global gate voltage also causes random telegraph noise, and therefore, there is a suitable point to operate quantum dot measurement.

  7. A strategy to stabilise the local structure of Ti{sup 4+} and Zn{sup 2+} species against aging in TiO{sub 2}/aluminium-doped ZnO bi-layers for applications in hybrid solar cells

    SciTech Connect (OSTI)

    Pellegrino, Giovanna; La Magna, Antonino; Bongiorno, Corrado; Smecca, Emanuele; Alberti, Alessandra, E-mail: alessandra.alberti@imm.cnr.it [CNR-IMM Zona Industriale VIII Strada 5, 95121 Catania (Italy); Condorelli, Guglielmo G. [Università degli studi di Catania and INSTM UdR Catania V.le A. Doria 6, Catania (Italy); Mocuta, Cristian [Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin BP 48, 91192, Gif-sur-Yvette Cedex (France)

    2014-08-07

    We explore a strategy to counteract aging issues in TiO{sub 2}/aluminium-doped ZnO bi-layers used in hybrid solar cells photo-anodes, mainly related to Zn diffusion in the TiO{sub 2} matrix. Different Ti{sup 4+} and Zn{sup 2+} local structures within the anatase grains and along the film thickness were found as a function of post-deposition annealing treatments in the range between 200?°C and 500?°C by synchrotron radiation extended x-ray absorption fine structure analyses. In particular, in the 500?°C-treated sample, diffusion of zinc species along the TiO{sub 2} grain-boundaries has been observed with aging (3?years). In contrast, a mild thermal budget at 200?°C favours a proper atomic arrangement of the zinc-containing anatase lattice which reduces Zn diffusion, thus guaranteeing a good stability with aging.

  8. Twist Solves Bilayer Graphene Mystery

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Twist Solves Bilayer Graphene Mystery Twist Solves Bilayer Graphene Mystery Print Wednesday, 26 March 2014 00:00 Researchers have discovered a unique new twist to the story of...

  9. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Bilayer Graphene Gets a Bandgap Bilayer Graphene Gets a Bandgap Print Wednesday, 26 August 2009 00:00 Graphene is the two-dimensional crystalline form of carbon whose extraordinary...

  10. Immobilized lipid-bilayer materials

    SciTech Connect (OSTI)

    Sasaki, Darryl Y. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM); Yamanaka, Stacey A. (Dallas, TX)

    2000-01-01

    A method for preparing encapsulated lipid-bilayer materials in a silica matrix comprising preparing a silica sol, mixing a lipid-bilayer material in the silica sol and allowing the mixture to gel to form the encapsulated lipid-bilayer material. The mild processing conditions allow quantitative entrapment of pre-formed lipid-bilayer materials without modification to the material's spectral characteristics. The method allows for the immobilization of lipid membranes to surfaces. The encapsulated lipid-bilayer materials perform as sensitive optical sensors for the detection of analytes such as heavy metal ions and can be used as drug delivery systems and as separation devices.

  11. Twist Solves Bilayer Graphene Mystery

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    spectroscopy (ARPES) to bilayer graphene. Through direct band-structure measurements and calculations, they discovered that in the stacking of graphene monolayers,...

  12. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene...

  13. Optical Determination of Gate--Tunable Bandgap in Bilayer Graphene

    E-Print Network [OSTI]

    Zhang, Yuanbo

    2010-01-01

    Tunable Bandgap in Bilayer Graphene Yuanbo Zhang* 1 , Tsung-gate-tunable bandgap in graphene bilayers with magnitude asbands. In two- dimensional graphene bilayers this bandgap

  14. Minimal Bending Energies of Bilayer Polyhedra

    E-Print Network [OSTI]

    Christoph A. Haselwandter; Rob Phillips

    2011-06-10

    Motivated by recent experiments on bilayer polyhedra composed of amphiphilic molecules, we study the elastic bending energies of bilayer vesicles forming polyhedral shapes. Allowing for segregation of excess amphiphiles along the ridges of polyhedra, we find that bilayer polyhedra can indeed have lower bending energies than spherical bilayer vesicles. However, our analysis also implies that, contrary to what has been suggested on the basis of experiments, the snub dodecahedron, rather than the icosahedron, generally represents the energetically favorable shape of bilayer polyhedra.

  15. Twist Solves Bilayer Graphene Mystery

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Twist Solves Bilayer Graphene Mystery Print Researchers have discovered a unique new twist to the story of graphene and, in the process, appear to have solved a mystery that has...

  16. Transverse electric plasmons in bilayer graphene

    E-Print Network [OSTI]

    Jablan, Marinko

    We predict the existence of transverse electric (TE) plasmons in bilayer graphene. We find that their plasmonic properties are much more pronounced in bilayer than in monolayer graphene, in a sense that they can get more ...

  17. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    suggestions for a way to improve these results? Development of Dual-Gated Bilayer Graphene Device Structures. Howell, Stephen Wayne ; Ohta, Taisuke ; Beechem Iii, Thomas Edwin...

  18. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  19. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  20. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  1. Transport Properties of Bilayer Graphene Nanoribbons

    E-Print Network [OSTI]

    Wang, Minsheng

    2013-01-01

    Biased Bilayer Graphene: Semiconductor with a Gap Tunable byUltrasmooth Graphene Nanoribbon Semiconductors. Sciencedimensional semiconductors and single-layer graphene films (

  2. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  3. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  4. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  5. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  6. Bilayer Graphene Gets a Bandgap

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room News PublicationsAudits & InspectionsBeryllium and ChronicBestBeyondBigger's NotBilayer

  7. Mimicking anhydrobiosis on solid supported lipid bilayers 

    E-Print Network [OSTI]

    Chapa, Vanessa Alyss

    2007-09-17

    may be involved. 54 In the last ten years, an alternative mechanism of anhydrobiosis, the formation of sugar glasses, or vitrification, has been proposed to work in conjunction with water replacement to stabilize dry bilayers. 57 Glasses... when dehydrated and although the specifics remain unclear, it has been proposed that vitrification inhibits the increase in T m . 60 Previous Studies of Liposomes Whereas the use of supported lipid bilayers in anhydrobiotic studies is novel...

  8. Subterahertz excitations and magnetoelectric effects in hexaferrite-piezoelectric bilayers

    E-Print Network [OSTI]

    Srinivasan, Gopalan

    Subterahertz excitations and magnetoelectric effects in hexaferrite-piezoelectric bilayers Alexey B 7 October 2008 A frequency-agile hexaferrite-piezoelectric composite for potential device applications at subterahertz frequencies is studied. The bilayer is composed of aluminum substituted barium

  9. POLYMER PROGRAM SEMINAR "Electromechanics of Biomimetic Bilayer Membranes"

    E-Print Network [OSTI]

    Alpay, S. Pamir

    and experimental work on the dynamics of biomimetic membranes (bilayers assembled from lipids or polymersPOLYMER PROGRAM SEMINAR "Electromechanics of Biomimetic Bilayer Membranes" Prof. Petia Vlahovska in the embedding electrolyte solutions destabilize the interface. However, the capacitive charging acts

  10. Adsorption on tunable bilayer graphene: A model approach

    SciTech Connect (OSTI)

    Alisultanov, Z. Z., E-mail: zaur0102@gmail.com [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2013-07-15

    The problem of the adsorption of atoms on the surface of tunable bilayer graphene is considered within the context of Anderson's model. Analytical expressions for the densities of states of bilayer graphene and an adatom are derived, and the charge exchange between adatoms and bilayer graphene is studied. The charge of adatoms of some elements is estimated. The change induced in the density of states of tunable bilayer graphene by the adsorption of atoms is explored.

  11. hal00276997, Raman spectra of misoriented bilayer graphene

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    hal­00276997, version 1 ­ 5 May 2008 Raman spectra of misoriented bilayer graphene P. Poncharal 1 spectra from single layer graphene with a bilayer in which the two layers are arbitrarily misoriented to the similarity of the electronic structures of single layer graphene and misoriented bilayer graphene. Another

  12. Bilayer graphene quantum dot defined by topgates

    SciTech Connect (OSTI)

    Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

    2014-06-21

    We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.

  13. Comments to topological defects in bilayer vesicles

    E-Print Network [OSTI]

    L. V. Elnikova

    2007-01-09

    To explain the details of bilayer vesicle aggregation, we revised the anyon model for lipid domains formation in closed vesicles of lipid-cholesterol system $DPPC/DLPC$/cholesterol, which was measured by Feigenson and Tokumasu (Biophys. Journal, 2001, 2003) in frames of the different optical experiments and atomic-force microscopy.

  14. Perspectives for gapped bilayer graphene polaritonics

    E-Print Network [OSTI]

    Simone De Liberato

    2015-07-13

    Bilayer graphene is normally a semimetal with parabolic dispersion, but a tunable bandgap up to few hundreds meV can be opened by breaking the symmetry between the layers through an external potential. Ab-initio calculations show that the optical response around the bandgap is strongly dominated by bound excitons, whose characteristics and selection rules differ from the usual excitons found in semiconductor quantum wells. In this work we study the physics of those excitons resonantly coupled to a photonic microcavity, assessing the possibility to reach the strong and the ultrastrong coupling regimes of light-matter interaction. We discover that both regimes are experimentally accessible, thus opening the way for a most promising technological platform, combining mid-infrared quantum polaritonics with the tunability and electronic features of graphene bilayers.

  15. Equilibrium insertion of nanoscale objects into phospholipid bilayers

    E-Print Network [OSTI]

    Sergey Pogodin; Vladimir A. Baulin

    2011-08-30

    Certain membrane proteins, peptides, nanoparticles and nanotubes have rigid structure and fixed shape. They are often viewed as spheres and cylinders with certain surface properties. Single Chain Mean Field theory is used to model the equilibrium insertion of nanoscale spheres and rods into the phospholipid bilayer. The equilibrium structures and the resulting free energies of the nano-objects in the bilayer allow to distinguish different orientations in the bilayer and estimate the energy barrier of insertion.

  16. How Bilayer Graphene Got a Bandgap

    ScienceCinema (OSTI)

    Feng Wang

    2010-01-08

    Graphene is the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But theres a catch: graphene has no bandgap. Now Feng Wang and his colleagues at Berkeley Lab and UC Berkeley have engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 milli-electron volts, which is the energy of infrared radiation.

  17. How Bilayer Graphene Got a Bandgap

    ScienceCinema (OSTI)

    Wang, Feng

    2013-05-29

    Graphene is the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But theres a catch: graphene has no bandgap. Now Feng Wang and his colleagues at Berkeley Lab and UC Berkeley have engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 milli-electron volts, which is the energy of infrared radiation.

  18. Bilayer membrane interactions with nanofabricated scaffolds

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Collier, Patrick C.

    2015-07-29

    Membrane function is facilitated by lateral organization within the lipid bilayer, including phase-separation of lipids into more ordered domains (lipid rafts) and anchoring of the membrane to a cytoskeleton. These features have proven difficult to reproduce in model membrane systems such as black lipid membranes, unilamellar vesicles and supported bilayers. However, advances in micro/nanofabrication have resulted in more realistic synthetic models of membrane-cytoskeleton interactions that can help uncover the design rules responsible for biological membrane formation and organization. This review will focus on describing micro-/nanostructured scaffolds that can emulate the connections of a cellular membrane to an underlying “cytoskeleton”. Thismore »includes molecular-based scaffolds anchored to a solid substrate through surface chemistry, solid-state supports modified by material deposition, lithography and etching, the creation of micro/nanoporous arrays, integration with microfluidics, and droplet-based bilayers at interfaces.Model systems such as these are increasing our understanding of structure and organization in cell membranes, and how they result in the emergence of functionality at the nanoscale.« less

  19. Functional One-Dimensional Lipid Bilayers on Carbon Nanotube Templates

    SciTech Connect (OSTI)

    Artyukhin, A; Shestakov, A; Harper, J; Bakajin, O; Stroeve, P; Noy, A

    2004-07-23

    We present one-dimensional (1-D) lipid bilayer structures that integrate carbon nanotubes with a key biological environment-phospholipid membrane. Our structures consist of lipid bilayers wrapped around carbon nanotubes modified with a hydrophilic polymer cushion layer. Despite high bilayer curvature, the lipid membrane maintains its fluidity and can sustain repeated damage-recovery cycles. We also present the first evidence of spontaneous insertion of pore-forming proteins into 1-D lipid bilayers. These structures could lead to the development of new classes of biosensors and bioelectronic devices.

  20. Atomistic mechanisms for bilayer growth of graphene on metal...

    Office of Scientific and Technical Information (OSTI)

    Atomistic mechanisms for bilayer growth of graphene on metal substrates This content will become publicly available on January 8, 2016 Prev Next Title: Atomistic mechanisms...

  1. Direct in situ measurement of specific capacitance, monolayer tension, and bilayer tension in a droplet interface bilayer

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Taylor, Graham J.; Venkatesan, Guru A.; Collier, C. Patrick; Sarles, Stephen A.

    2015-08-05

    In this study, thickness and tension are important physical parameters of model cell membranes. However, traditional methods to measure these quantities require multiple experiments using separate equipment. This work introduces a new multi-step procedure for directly accessing in situ multiple physical properties of droplet interface bilayers (DIB), including specific capacitance (related to thickness), lipid monolayer tension in the Plateau-Gibbs border, and bilayer tension. The procedure employs a combination of mechanical manipulation of bilayer area followed by electrowetting of the capacitive interface to examine the sensitivities of bilayer capacitance to area and contact angle to voltage, respectively. These data allow formore »determining the specific capacitance of the membrane and surface tension of the lipid monolayer, which are then used to compute bilayer thickness and tension, respectively. The use of DIBs affords accurate optical imaging of the connected droplets in addition to electrical measurements of bilayer capacitance, and it allows for reversibly varying bilayer area. After validating the accuracy of the technique with diphytanoyl phosphatidylcholine (DPhPC) DIBs in hexadecane, the method is applied herein to quantify separately the effects on membrane thickness and tension caused by varying the solvent in which the DIB is formed and introducing cholesterol into the bilayer. Because the technique relies only on capacitance measurements and optical images to determine both thickness and tension, this approach is specifically well-suited for studying the effects of peptides, biomolecules, natural and synthetic nanoparticles, and other species that accumulate within membranes without altering bilayer conductance.« less

  2. Performance of Anode-Supported Solid Oxide Fuel Cell with Thin Bi-Layer Electrolyte by Pulsed Laser Deposition

    SciTech Connect (OSTI)

    Lu, Zigui; Hardy, John S.; Templeton, Jared W.; Stevenson, Jeffry W.; Fisher, Daniel; Wu, Naijuan; Ignatiev, Alex

    2012-07-15

    Anode-supported yttria stabilized zirconia (YSZ)/samaria doped ceria (SDC) bi-layer electrolytes with uniform thickness and high density were fabricated by pulsed laser deposition at 1000 degrees C. Fuel cells with such bi-layer electrolytes were fabricated and tested, yielding open circuit voltages from 0.94 to 1.0 V at 600-700 degrees C. Power densities from 0.4 to 1.0 W cm{sup -2} at 0.7 V were achieved in air at temperatures of 600-700 degrees C. Cell performance was improved in flowing oxygen, with an estimated peak power density of over 2 W cm{sup -2} at 650 degrees C, assuming the same overall resistance over the entire range of current density. The high cell performance was attributed to the very low ohmic resistance of the fuel cell, owing to the small thickness of the electrolyte. Stable performance was also demonstrated in that the voltage of the fuel cell showed very little change at a constant current density of 1 A cm{sup -2} during more than 400 hours of operation at 650 degrees C in flowing oxygen. SEM analysis of the fuel cell after testing showed that the bi-layer electrolyte had retained its chemical and mechanical integrity.

  3. Hot Carrier-Assisted Intrinsic Photoresponse in Graphene

    E-Print Network [OSTI]

    Gabor, Nathaniel M.

    We report on the intrinsic optoelectronic response of high-quality dual-gated monolayer and bilayer graphene p-n junction devices. Local laser excitation (of wavelength 850 nanometers) at the p-n interface leads to striking ...

  4. Direct observation of a widely tunable bandgap in bilayer graphene

    E-Print Network [OSTI]

    Zettl, Alex

    . Most notably, the inversion symmetric AB-stacked bilayer graphene is a zero-bandgap semiconductor in the graphene FET device we are able to control independently the two key semiconductor parameters: electronicLETTERS Direct observation of a widely tunable bandgap in bilayer graphene Yuanbo Zhang1 *, Tsung

  5. Self-assembled lipid bilayer materials

    DOE Patents [OSTI]

    Sasaki, Darryl Y.; Waggoner, Tina A.; Last, Julie A.

    2005-11-08

    The present invention is a self-assembling material comprised of stacks of lipid bilayers formed in a columnar structure, where the assembly process is mediated and regulated by chemical recognition events. The material, through the chemical recognition interactions, has a self-regulating system that corrects the radial size of the assembly creating a uniform diameter throughout most of the structure. The materials form and are stable in aqueous solution. These materials are useful as structural elements for the architecture of materials and components in nanotechnology, efficient light harvesting systems for optical sensing, chemical processing centers, and drug delivery vehicles.

  6. Collective Excitations in Electron-Hole Bilayers

    SciTech Connect (OSTI)

    Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Golden, K. I. [Department of Mathematics and Statistics and Department of Physics, University of Vermont, Burlington, Vermont 05401 (United States)

    2007-06-08

    We report a combined analytic and molecular dynamics analysis of the collective mode spectrum of a bipolar (electron-hole) bilayer in the strong coupling classical limit. A robust, isotropic energy gap is identified in the out-of-phase spectra, generated by the combined effect of correlations and of the excitation of the bound dipoles. In the in-phase spectra we identify longitudinal and transverse acoustic modes wholly maintained by correlations. Strong nonlinear generation of higher harmonics of the fundamental dipole oscillation frequency and the transfer of harmonics between different modes is observed.

  7. LETTER doi:10.1038/nature14364 Topological valley transport at bilayer graphene

    E-Print Network [OSTI]

    Wang, Feng

    semiconductor bandgap can be induced in bilayer graphene using a vertical electrical field, and differentLETTER doi:10.1038/nature14364 Topological valley transport at bilayer graphene domain walls Long in bilayer graphene. A tunable bandgap can be induced in bilayer graphene by an external electric field1

  8. Interaction of Alamethicin Pores in DMPC Bilayers

    E-Print Network [OSTI]

    Doru Constantin; Guillaume Brotons; Ansgar Jarre; Chenghao Li; Tim Salditt

    2015-04-11

    We have investigated the x-ray scattering signal of highly aligned multilayers of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine containing pores formed by the antimicrobial peptide alamethicin as a function of the peptide/lipid ratio. We are able to obtain information on the structure factor of the pore fluid, which then yields the interaction potential between pores in the plane of the bilayers. Aside from a hard core with a radius corresponding to the geometric radius of the pore, we find a repulsive lipid-mediated interaction with a range of $\\simeq 30$ {\\AA} and a contact value of 2.4 $k_BT$. This result is in qualitative agreement with recent theoretical models.

  9. Electrostatic and Magnetic Fields in Bilayer Graphene

    E-Print Network [OSTI]

    Ahmed Jellal; Ilham Redouani; Hocine Bahlouli

    2014-11-14

    We compute the transmission probability through rectangular potential barriers and p-n junctions in the presence of a magnetic and electric fields in bilayer graphene taking into account the full four bands of the energy spectrum. For energy E higher than the interlayer coupling $\\gamma_1 (E>\\gamma_1)$ two propagation modes are available for transport giving rise to four possible ways for transmission and reflection probabilities. However, when the energy is less then the height of the barrier the Dirac fermions exhibits transmission resonances and only one mode of propagation is available. We study the effect of the interlayer electrostatic potential $\\delta$ and the different geometry parameters of the barrier on the transmission probability.

  10. Interfacial Widths of Conjugated Polymer Bilayers

    SciTech Connect (OSTI)

    NCSU; UC Berkeley; UCSB; Advanced Light Source; Garcia, Andres; Yan, Hongping; Sohn, Karen E.; Hexemer, Alexander; Nguyen, Thuc-Quyen; Bazan, Guillermo C.; Kramer, Edward J.; Ade, Harald

    2009-08-13

    The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown by resonant soft X-ray reflectivity (RSoXR) to be very smooth and sharp. The chemical interdiffusion due to casting is limited to less than 0.6 nm, and the interface created is thus nearly 'molecularly' sharp. These results demonstrate for the first time and with high precision that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent. A baseline is established for understanding the role of interfacial structure in determining the performance of CPE-based polymer light-emitting diodes. More broadly, we anticipate further applications of RSoXR as an important tool in achieving a deeper understanding of other multilayer organic optoelectronic devices, including multilayer photovoltaic devices.

  11. Collective Dynamics of Complex Plasma Bilayers

    SciTech Connect (OSTI)

    Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts 02467 (United States); Kalman, G. J. [Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts 02467 (United States); Kyrkos, S. [Department of Chemistry and Physics, Le Moyne College, 1419 Salt Springs Road, Syracuse, New York 13214 (United States); Golden, K. I. [Department of Mathematics and Statistics, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05401-1455 (United States); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California, 92093 (United States)

    2009-12-11

    A classical dusty plasma experiment was performed using two different dust grain sizes to form a strongly coupled asymmetric bilayer (two closely spaced interacting monolayers) of two species of charged dust particles. The observation and analysis of the thermally excited particle oscillations revealed the collective mode structure and dispersion (wave propagation) in this system; in particular, the existence of the theoretically predicted k=0 energy (frequency) gap was verified. Equilibrium molecular-dynamics simulations were performed to emulate the experiment, assuming Yukawa-type interparticle interaction. The simulations and analytic calculations based both on lattice summation and on the quasilocalized charge approximation approach are in good agreement with the experimental findings and help in identifying and characterizing the observed phenomena.

  12. Rapid Impedance Measurement of Tethered Bilayer Lipid Membrane Biosensors

    E-Print Network [OSTI]

    Mason, Andrew

    Rapid Impedance Measurement of Tethered Bilayer Lipid Membrane Biosensors Xiaoyi Mu, Daniel Rairigh of millisecond membrane protein activity in biosensor arrays. I. INTRODUCTION Because of the critical role membrane proteins play in biological function, biosensors utilizing membrane proteins have become

  13. Label-Free Sensing on Supported Lipid Bilayers 

    E-Print Network [OSTI]

    Robison, Aaron Douglas 1982-

    2012-11-28

    peptides, but thermodynamic data can be extracted as well. In a final set of experiments, the interaction of proteins with phosphatidylserine (PS) in supported lipid bilayers is observed by utilizing PS-Cu2+-induced quenching of fluorophores. Disruption...

  14. Water permeation through stratum corneum lipid bilayers from atomistic simulations

    E-Print Network [OSTI]

    Chinmay Das; Peter D. Olmsted; Massimo G. Noro

    2009-07-09

    Stratum corneum, the outermost layer of skin, consists of keratin filled rigid non-viable corneocyte cells surrounded by multilayers of lipids. The lipid layer is responsible for the barrier properties of the skin. We calculate the excess chemical potential and diffusivity of water as a function of depth in lipid bilayers with compositions representative of the stratum corneum using atomistic molecular dynamics simulations. The maximum in the excess free energy of water inside the lipid bilayers is found to be twice that of water in phospholipid bilayers at the same temperature. Permeability, which decreases exponentially with the free energy barrier, is reduced by several orders of magnitude as compared to with phospholipid bilayers. The average time it takes for a water molecule to cross the bilayer is calculated by solving the Smoluchowski equation in presence of the free energy barrier. For a bilayer composed of a 2:2:1 molar ratio of ceramide NS 24:0, cholesterol and free fatty acid 24:0 at 300K, we estimate the permeability P=3.7e-9 cm/s and the average crossing time \\tau_{av}=0.69 ms. The permeability is about 30 times smaller than existing experimental results on mammalian skin sections.

  15. The ground state construction of bilayer graphene

    E-Print Network [OSTI]

    Alessandro Giuliani; Ian Jauslin

    2015-07-31

    We consider a model of half-filled bilayer graphene, in which the three dominant Slonczewski-Weiss-McClure hopping parameters are retained, in the presence of short range interactions. Under a smallness assumption on the interaction strength $U$ as well as on the inter-layer hopping $\\epsilon$, we construct the ground state in the thermodynamic limit, and prove its analyticity in $U$, uniformly in $\\epsilon$. The interacting Fermi surface is degenerate, and consists of eight Fermi points, two of which are protected by symmetries, while the locations of the other six are renormalized by the interaction, and the effective dispersion relation at the Fermi points is conical. The construction reveals the presence of different energy regimes, where the effective behavior of correlation functions changes qualitatively. The analysis of the crossover between regimes plays an important role in the proof of analyticity and in the uniform control of the radius of convergence. The proof is based on a rigorous implementation of fermionic renormalization group methods, including determinant estimates for the renormalized expansion.

  16. Exceptional Optoelectronic Properties of Hydrogenated Bilayer Silicene

    SciTech Connect (OSTI)

    Huang, Bing [ORNL] [ORNL; Yoon, Mina [ORNL] [ORNL; Smith, Sean C [ORNL] [ORNL; Wei, Su-Huai [National Renewable Energy Laboratory (NREL)] [National Renewable Energy Laboratory (NREL); Deng, Hui-Xiong [National Renewable Energy Laboratory (NREL)] [National Renewable Energy Laboratory (NREL); Liu, Feng [University of Utah] [University of Utah; Lee, Hoonkyung [Konkuk University, South Korea] [Konkuk University, South Korea; Sumpter, Bobby G [ORNL] [ORNL

    2014-01-01

    Silicon is arguably the best electronic material, but not as good an optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS) shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable bandgap. At low hydrogen concentrations, four ground states of single- and double-side hydrogenated BS are characterized with dipole-allowed direct (or quasidirect) bandgaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-side hydrogenated BS structures exhibit direct (or quasidirect) bandgaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, high-efficiency, optoelectronic applications.

  17. The ground state construction of bilayer graphene

    E-Print Network [OSTI]

    Alessandro Giuliani; Ian Jauslin

    2015-07-22

    We consider a model of half-filled bilayer graphene, in which the three dominant Slonczewski-Weiss-McClure hopping parameters are retained, in the presence of short range interactions. Under a smallness assumption on the interaction strength $U$ as well as on the inter-layer hopping $\\epsilon$, we construct the ground state in the thermodynamic limit, and prove its analyticity in $U$, uniformly in $\\epsilon$. The interacting Fermi surface is degenerate, and consists of eight Fermi points, two of which are protected by symmetries, while the locations of the other six are renormalized by the interaction, and the effective dispersion relation at the Fermi points is conical. The construction reveals the presence of different energy regimes, where the effective behavior of correlation functions changes qualitatively. The analysis of the crossover between regimes plays an important role in the proof of analyticity and in the uniform control of the radius of convergence. The proof is based on a rigorous implementation of fermionic renormalization group methods, including determinant estimates for the renormalized expansion.

  18. Green exciplex emission from a bilayer light-emitting diode containing a rare earth ternary complex

    E-Print Network [OSTI]

    Huang, Yanyi

    Green exciplex emission from a bilayer light-emitting diode containing a rare earth ternary complex form 18 October 2001 Abstract A bilayer organic light-emitting diode using a blue-fluorescent yttrium

  19. Influence of Hydrophobic Mismatch on Structures and Dynamics of Gramicidin A and Lipid Bilayers

    E-Print Network [OSTI]

    Kim, Taehoon; Lee, Kyu II; Morris, Phillip; Pastor, Richard W.; Andersen, Olaf S.; Im, Wonpil

    2012-04-04

    Gramicidin A (gA) is a 15-amino-acid antibiotic peptide with an alternating L-D sequence, which forms (dimeric) bilayer-spanning, monovalent cation channels in biological membranes and synthetic bilayers. We performed ...

  20. Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations

    E-Print Network [OSTI]

    Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations Denis L 2014) We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene that at temperature T specific heat varies with temperature as Tn , where n ¼ 1 for graphene, n ¼ 1

  1. Fractal Landau-Level Spectra in Twisted Bilayer Graphene Z. F. Wang,,

    E-Print Network [OSTI]

    Simons, Jack

    Fractal Landau-Level Spectra in Twisted Bilayer Graphene Z. F. Wang,, Feng Liu,*, and M. Y. Chou bilayer graphene serves as a special system with a fractal energy spectrum under laboratory accessible in twisted bilayer graphene for both commensurate and incommensurate rotational angles and provide

  2. Isoelectronic co-doping

    DOE Patents [OSTI]

    Mascarenhas, Angelo

    2004-11-09

    Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  3. Graphene Monolayer Rotation on Ni(111) Facilities Bilayer Graphene Growth

    SciTech Connect (OSTI)

    Batzill M.; Sutter P.; Dahal, A.; Addou, R.

    2012-06-11

    Synthesis of bilayer graphene by chemical vapor deposition is of importance for graphene-based field effect devices. Here, we demonstrate that bilayer graphene preferentially grows by carbon-segregation under graphene sheets that are rotated relative to a Ni(111) substrate. Rotated graphene monolayer films can be synthesized at growth temperatures above 650 C on a Ni(111) thin-film. The segregated second graphene layer is in registry with the Ni(111) substrate and this suppresses further C-segregation, effectively self-limiting graphene formation to two layers.

  4. The component groups structure of DPPC bilayers obtained by specular neutron reflectometry

    E-Print Network [OSTI]

    Michal Beli?ka; Yuri Gerelli; Norbert Ku?erka; Giovanna Fragneto

    2014-12-16

    Specular neutron reflectometry (SNR) was measured on a system of a floating bilayer consisting of 1,2-dipalmitoyl-d62-\\textit{sn}-glycero-3-phosphocholine (d62-diC16:0PC) deposited over a 1,2-dibehenoyl-\\textit{sn}-glycero-3-phosphocholine (diC22:0PC) bilayer at 25 and 55 {\\deg}C. The internal structure of lipid bilayers was described by a one dimensional scattering length density profile (SLDP) model, originally developed for the evaluation of small angle scattering data. The corresponding model reflectivity curves successfully describe the experimental reflectivity curves of a supported bilayer in the gel phase and a system of a floating bilayer in the liquid crystalline phase. The reflectivity data from the supported bilayer were evaluated individually and served further as an input by the data treatment of floating bilayer reflectivity curves. The results yield internal structure of a deposited and floating bilayer on the level of component groups of lipid molecules. The obtained structure of the floating d62-diC16:0PC bilayer displays high resemblance to the bilayer structure in the form of unilamellar vesicles, however, simultaneously it shows rate of fluctuations in comparison to unilamellar vesicle bilayers.

  5. BoseEinstein condensation of excitons in bilayer electron systems

    E-Print Network [OSTI]

    Eisenstein, Jim

    Bose­Einstein condensation of excitons in bilayer electron systems J. P. Eisenstein1 * & A. H. Mac is represented by a wave that has both amplitude and phase. The most remarkable consequence of Bose­Einstein cousins, any number of bosons can crowd into the same microscopic state. Indeed, Einstein predicted

  6. Tethered Lipid Bilayers on Electrolessly Deposited Gold for Bioelectronic Applications

    E-Print Network [OSTI]

    Lee, Ilsoon

    of Public Health, The University of Michigan, Ann Arbor, Michigan 48109-2029 Received April 24, 2006 electron microscopy, energy dispersive spectroscopy, and atomic force microscopy. Bilayer lipid membranes) there is no cushion between the surface and the sBLM to provide space for extramembrane moieties of membrane proteins

  7. Berry phase and pseudospin winding number in bilayer graphene

    E-Print Network [OSTI]

    Marzari, Nicola

    Ever since the novel quantum Hall effect in bilayer graphene was discovered, and explained by a Berry phase of 2? [ K. S. Novoselov et al. Nat. Phys. 2 177 (2006)], it has been widely accepted that the low-energy electronic ...

  8. Water Order Profiles on Phospholipid/Cholesterol Membrane Bilayer Surfaces

    E-Print Network [OSTI]

    O'Shea, Paul

    Water Order Profiles on Phospholipid/Cholesterol Membrane Bilayer Surfaces DAVID ROBINSON,1 2011 in Wiley Online Library (wileyonlinelibrary.com). Abstract: Water is pivotal in the stabilization of macromolecular biological structures, although the dynamic en- semble structure of water near to molecular

  9. Modification of a Supported Lipid Bilayer by Polyelectrolyte Adsorption

    E-Print Network [OSTI]

    Granick, Steve

    transitions in phospholipid bilayers are dynamic scanning calorimetry,9 X-ray scattering,10 and neutron microscopy (AFM).12-14 Ellipsometry is another technique that can monitor film thickness change as a function. In particular, one of the most important physical properties of a lipid system is its gel-fluid phase transition

  10. Structure and Interactions of Fully Hydrated Dioleoylphosphatidylcholine Bilayers

    E-Print Network [OSTI]

    Nagle, John F.

    that estimates of the Hamaker parameter H and the bending modulus Kc are strongly coupled. INTRODUCTION One- phatidylcholine (DPPC) L phase bilayer (Nagle et al., 1996). In the present paper, we turn our attention address in this paper. There are several methodologies for obtaining L phase structure. The traditional

  11. How to make a bilayer exciton condensate flow

    E-Print Network [OSTI]

    Loss, Daniel

    ARTICLES How to make a bilayer exciton condensate flow JUNG-JUNG SU* AND A. H. MACDONALD Department@physics.utexas.edu. Published online: 24 August 2008; doi:10.1038/nphys1055 Among the many examples of Bose condensation considered in physics, electron­hole-pair (exciton) condensation has maintained special interest because

  12. The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes

    E-Print Network [OSTI]

    Nelson, Philip

    The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes Udo Seifert 1 ; Julian Shillcock into the elastic theory of tilted fluid membranes. It can drive an instability of the flat phase; it also provides to order. In analogy to smectic liquid crystals, one expects a soft tilt degree of freedom to ap­ pear

  13. The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes

    E-Print Network [OSTI]

    Nelson, Philip

    The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes Udo Seifert 1 , Julian Shillcock difference introduces a length scale into the elastic theory of tilted fluid membranes. It can drive of mem­ branes as their hydrocarbon chains begin to order. In analogy to smectic liquid crystals, one

  14. Cholesterol enhances surface water diffusion of phospholipid bilayers

    SciTech Connect (OSTI)

    Cheng, Chi-Yuan; Kausik, Ravinath; Han, Songi, E-mail: songi@chem.ucsb.edu [Department of Chemistry and Biochemistry and Materials Research Laboratory, University of California, Santa Barbara, California 93106 (United States); Olijve, Luuk L. C. [Laboratory of Macromolecular and Organic Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven (Netherlands)

    2014-12-14

    Elucidating the physical effect of cholesterol (Chol) on biological membranes is necessary towards rationalizing their structural and functional role in cell membranes. One of the debated questions is the role of hydration water in Chol-embedding lipid membranes, for which only little direct experimental data are available. Here, we study the hydration dynamics in a series of Chol-rich and depleted bilayer systems using an approach termed {sup 1}H Overhauser dynamic nuclear polarization (ODNP) NMR relaxometry that enables the sensitive and selective determination of water diffusion within 5–10 Å of a nitroxide-based spin label, positioned off the surface of the polar headgroups or within the nonpolar core of lipid membranes. The Chol-rich membrane systems were prepared from mixtures of Chol, dipalmitoyl phosphatidylcholine and/or dioctadecyl phosphatidylcholine lipid that are known to form liquid-ordered, raft-like, domains. Our data reveal that the translational diffusion of local water on the surface and within the hydrocarbon volume of the bilayer is significantly altered, but in opposite directions: accelerated on the membrane surface and dramatically slowed in the bilayer interior with increasing Chol content. Electron paramagnetic resonance (EPR) lineshape analysis shows looser packing of lipid headgroups and concurrently tighter packing in the bilayer core with increasing Chol content, with the effects peaking at lipid compositions reported to form lipid rafts. The complementary capability of ODNP and EPR to site-specifically probe the hydration dynamics and lipid ordering in lipid membrane systems extends the current understanding of how Chol may regulate biological processes. One possible role of Chol is the facilitation of interactions between biological constituents and the lipid membrane through the weakening or disruption of strong hydrogen-bond networks of the surface hydration layers that otherwise exert stronger repulsive forces, as reflected in faster surface water diffusivity. Another is the concurrent tightening of lipid packing that reduces passive, possibly unwanted, diffusion of ions and water across the bilayer.

  15. Hierarchy of fillings for FQHE in monolayer and in bilayer graphene: Explanation of $?=-\\frac{1}{2}$ fractional quantum Hall state in bilayer graphene

    E-Print Network [OSTI]

    Janusz Jacak; Lucjan Jacak

    2015-02-04

    The commensurability condition is applied to determine the hierarchy of fractional fillings of Landau levels in monolayer and bilayer graphene. The filling rates for FQHE in graphene are found and illustrated in the first three Landau levels. The good agreement with the experimental data is achieved. The presence of even denominator filling fractions in the hierarchy for FQHE in bilayer graphene is explained.

  16. Double Barriers and Magnetic Field in Bilayer Graphene

    E-Print Network [OSTI]

    Ilham Redouani; Ahmed Jellal; Hocine Bahlouli

    2015-05-21

    We study the transmission probability in an AB-stacked bilayer graphene of Dirac fermions scattered by a double barrier structure in the presence of a magnetic field. We take into account the full four bands of the energy spectrum and use the boundary conditions to determine the transmission probability. Our numerical results show that for energies higher than the interlayer coupling, four ways for transmission probabilities are possible while for energies less than the height of the barrier, Dirac fermions exhibits transmission resonances and only one transmission channel is available. We show that, for AB-stacked bilayer graphene, there is no Klein tunneling at normal incident. We find that the transmission displays sharp peaks inside the transmission gap around the Dirac point within the barrier regions while they are absent around the Dirac point in the well region. The effect of the magnetic field, interlayer electrostatic potential and various barrier geometry parameters on the transmission probabilities are also discussed.

  17. The Role of Lipid Bilayer Mechanics in Mechanosensation

    E-Print Network [OSTI]

    Tristan Ursell; Rob Phillips; Jane' Kondev; Dan Reeves; Paul A. Wiggins

    2007-02-13

    Mechanosensation is a key part of the sensory repertoire of a vast array of different cells and organisms. The molecular dissection of the origins of mechanosensation is rapidly advancing as a result of both structural and functional studies. One intriguing mode of mechanosensation results from tension in the membrane of the cell (or vesicle) of interest. The aim of this review is to catalogue recent work that uses a mix of continuum and statistical mechanics to explore the role of the lipid bilayer in the function of mechanosensitive channels that respond to membrane tension. The role of bilayer deformation will be explored in the context of the well known mechanosensitive channel MscL. Additionally, we make suggestions for bridging gaps between our current theoretical understanding and common experimental techniques.

  18. Stacking-dependent electronic structure of bilayer silicene

    SciTech Connect (OSTI)

    Fu, Huixia; Zhang, Jin; Ding, Zijing; Li, Hui, E-mail: huili8@iphy.ac.cn, E-mail: smeng@iphy.ac.cn; Meng, Sheng, E-mail: huili8@iphy.ac.cn, E-mail: smeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-03-31

    Bilayer silicene (BLS) is a class of material that possibly holds both topological and superconducting properties; however, its structure is not fully understood. By scanning stacking modes and lattice constants using first principles calculations, several meta-stable configurations are identified, including a slightly faulted-AA packing structure, named slide-2AA. Different from the metallic properties of conventional AA and AB stacking forms, band structure of slide-2AA bilayer presents a sizeable indirect energy gap of ?1.16?eV. A metal-semiconductor phase transition along the sliding pathway with a small energy barrier is also observed, indicating its electronic properties can be easily tuned by applying small shear force along the BLS surface plane. Such unique quantitative relationship of structure and electronic properties has profound implications in nanoelectronics and electromechanical devices.

  19. Doped zinc oxide microspheres

    DOE Patents [OSTI]

    Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  20. Doped zinc oxide microspheres

    DOE Patents [OSTI]

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-12-14

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  1. Band Tunneling through Double Barrier in Bilayer Graphene

    E-Print Network [OSTI]

    Hasan A. Alshehab; Hocine Bahlouli; Abderrahim El Mouhafid; Ahmed Jellal

    2014-01-20

    By taking into account the full four band energy spectrum, we calculate the transmission probability and conductance of electrons across symmetric and asymmetric double potential barrier with a confined interlayer potential difference in bilayer graphene. For energies less than the interlayer coupling \\gamma_{1}, E \\gamma_{1}, we obtain four possible ways for transmission resulting from the two propagating modes. We compute the associated transmission probabilities as well as their contribution to the conductance, study the effect of the double barrier geometry.

  2. Collective Modes in Strongly Coupled Electronic Bilayer Liquids

    SciTech Connect (OSTI)

    Kalman, G.; Valtchinov, V. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States)] [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Valtchinov, V. [Department of Radiology, Brigham and Women`s Hospital, Harvard Medical School, Boston, Massachusetts 02115 (United States)] [Department of Radiology, Brigham and Women`s Hospital, Harvard Medical School, Boston, Massachusetts 02115 (United States); Golden, K.I. [Department of Mathematics and Statistics, University of Vermont, Burlington, Vermont 05401 (United States)] [Department of Mathematics and Statistics, University of Vermont, Burlington, Vermont 05401 (United States)

    1999-04-01

    We present the first reliable calculation of the collective mode structure of a strongly coupled electronic bilayer. The calculation is based on a classical model through the 3rd frequency-moment-sum rule preserving quasi-localized-charge approximation, using the recently calculated hypernetted-chain pair correlation functions. The out-of-phase spectrum shows an energy gap at k=0 and the absence of a previously conjectured dynamical instability. {copyright} {ital 1999} {ital The American Physical Society}

  3. Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding shell Model of Monomer Distribution

    SciTech Connect (OSTI)

    Richter, Andrew G [ORNL; Dergunov, Sergey [ORNL; Ganus, Bill [University of Memphis; Thomas, Zachary P [ORNL; Pingali, Sai Venkatesh [ORNL; Urban, Volker S [ORNL; Liu, Yun [National Institute of Standards and Technology (NIST); Porcar, Lionel [ORNL; Pinkhassik, Eugene [University of Memphis

    2011-01-01

    Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

  4. Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

    SciTech Connect (OSTI)

    Richter, Andrew [Valparaiso University; Dergunov, Sergey [University of Memphis; Ganus, Bill [University of Memphis; Thomas, Zachary [University of Memphis; Pingali, Sai Venkatesh [ORNL; Urban, Volker S [ORNL; Liu, Yun [National Institute of Standards and Technology (NIST); Porcar, Lionel [Institut Laue-Langevin (ILL); Pinkhassik, Eugene [University of Memphis

    2011-01-01

    Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

  5. Diamondization of Graphene and Graphene-BN Bilayers: Chemical Functionalization and Electronic Structure Engineering

    E-Print Network [OSTI]

    Yuan, Long; Yang, Jinlong; Hou, Jian Guo

    2011-01-01

    In this article, based on first-principles calculations, we systematically study functionalization induced diamonization of graphene bilayer and graphene-BN hybrid bilayer. With single-side functionalization, the diamondized structures are magnetic semiconductor. Interestingly, if both sides of the bilayer are functionalized, diamondization becomes spontaneous without a barrier. On the other hand, when the bottom layer of the bilayer graphene is replaced by a single hexagonal BN layer, the diamondized structure becomes nonmagnetic metal. The tunable electronic and magnetic properties pave new avenues to construct graphene-based electronics and spintronics devices.

  6. Hierarchy of fillings for FQHE in monolayer and in bilayer graphene: Explanation of $\

    E-Print Network [OSTI]

    Jacak, Janusz

    2015-01-01

    The commensurability condition is applied to determine the hierarchy of fractional fillings of Landau levels in monolayer and bilayer graphene. The filling rates for FQHE in graphene are found and illustrated in the first three Landau levels. The good agreement with the experimental data is achieved. The presence of even denominator filling fractions in the hierarchy for FQHE in bilayer graphene is explained.

  7. PHYSICAL REVIEW B 83, 195317 (2011) Microwave-induced Hall resistance in bilayer electron systems

    E-Print Network [OSTI]

    Gusev, Guennady

    2011-01-01

    on dissipative and Hall resistance in high-quality bilayer electron systems is investigated experimentally. We of the microwave electric field and polarization exhibit a strong and nontrivial power and polarization dependencePHYSICAL REVIEW B 83, 195317 (2011) Microwave-induced Hall resistance in bilayer electron systems S

  8. Chemical passivity of III-VI bilayer terminated Si,,111... Jonathan A. Adamsa

    E-Print Network [OSTI]

    Olmstead, Marjorie

    Chemical passivity of III-VI bilayer terminated Si,,111... Jonathan A. Adamsa and Aaron A online 17 October 2005 The chemical stability of Si 111 , terminated with bilayer AlSe and GaSe, upon electronic and atomic structure do not imply similar chemical passivity. While Si 111 :GaSe is largely

  9. Measurement of chain tilt angle in fully hydrated bilayers of gel phase lecithins

    E-Print Network [OSTI]

    Nagle, John F.

    Measurement of chain tilt angle in fully hydrated bilayers of gel phase lecithins S. Tristram angle Otilt of the hydrocarbon chains has been determined for the fully hydrated gel phase of a series hydrocarbon chains, requiring each bilayer to scatter coherently rather than each monolayer. For DPPC, Otilt

  10. Enveloping of Charged Proteins by Lipid Bilayers Daniel Harries,*, Avinoam Ben-Shaul,*, and Igal Szleifer

    E-Print Network [OSTI]

    Ben-Shaul, Avinoam

    Enveloping of Charged Proteins by Lipid Bilayers Daniel Harries,*, Avinoam Ben-Shaul,*, and Igal an oppositely charged protein is studied with use of a simple theoretical model. The free energy of the bilayer-enveloped protein complex is expressed as a sum of electrostatic and curvature elasticity contributions

  11. BILAYER PLATES: MODEL REDUCTION, -CONVERGENT FINITE ELEMENT APPROXIMATION AND DISCRETE GRADIENT FLOW

    E-Print Network [OSTI]

    Bonito, Andrea

    by the deformation as in the case of the bending of a piece of paper. A related numerical method has been devised for the practical computation of large bilayer bending deformations. Our contributions in this paper are FLOW S¨OREN BARTELS, ANDREA BONITO , AND RICARDO H. NOCHETTO Abstract. The bending of bilayer plates

  12. Bilayer thickness effects on nanoindentation behavior of Ag/Ni multilayers

    E-Print Network [OSTI]

    Hong, Soon Hyung

    by nanoindentation hardness and creep tests. The hardness increased with decreasing bilayer thickness, although of nanoindentation creep tests on Ag/Ni nanomultilayers with various bilayer thicknesses. Multilayered Ag/Ni films thickness. A nanoindentation creep test was used to study the creep behavior of nano- scale multilayers

  13. Buckling analysis of singly curved shallow bi-layered arch under concentrated loading 

    E-Print Network [OSTI]

    Sonawane, Mahesh

    2009-05-15

    Bi-layered materials are a reduced weight derivative of the sandwich structure and are comprised of one thin skin face reinforced by a thick layer of low density material. Bi-layered materials are characterized by high flexural stiffness and are a...

  14. Polymer-Cushioned Bilayers. I. A Structural Study of Various Preparation Methods Using Neutron Reflectometry

    E-Print Network [OSTI]

    Wong, Joyce

    Polymer-Cushioned Bilayers. I. A Structural Study of Various Preparation Methods Using Neutron of preparing polymer-cushioned lipid bilayers. Four different techniques to deposit adsorption onto a previously dried polymer layer; 2) vesicle adsorption onto a bare substrate, followed

  15. Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations

    SciTech Connect (OSTI)

    Nika, Denis L. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States); Cocemasov, Alexandr I. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Balandin, Alexander A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States)

    2014-07-21

    We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene. The calculations were performed using the Born-von Karman model of lattice dynamics for intralayer atomic interactions and spherically symmetric interatomic potential for interlayer interactions. We found that at temperature T?bilayer graphene, and n?=?1.3 for the twisted bilayer graphene. The phonon specific heat reveals an intriguing dependence on the twist angle in bilayer graphene, which is particularly pronounced at low temperature. The results suggest a possibility of phonon engineering of thermal properties of layered materials by twisting the atomic planes.

  16. Critical adsorption controls translocation of polymer chains through lipid bilayers and permeation of solvent

    E-Print Network [OSTI]

    Jens-Uwe Sommer; Marco Werner; Vladimir A. Baulin

    2012-05-21

    Monte Carlo simulations using an explicit solvent model indicate a new pathway for translocation of a polymer chain through a lipid bilayer. We consider a polymer chain composed of repeat units with a given hydrophobicity and a coarse-grained model of a lipid bilayer in the self-organized liquid state. By varying the degree of hydrophobicity the chain undergoes an adsorption transition with respect to the lipid bilayer. Close to the transition point, at a properly balanced hydrophobicity of the chain, the membrane becomes transparent with respect to the chain. At the same time the solvent permeability of the bilayer is strongly increased in the region close to adsorbed chain. Our results indicate that the critical point of adsorption of the polymer chain interacting with the fluctuating lipid bilayer could play a key role for the translocation of molecules though biological membranes.

  17. The lipid bilayer at the mesoscale: a physical continuum model

    E-Print Network [OSTI]

    Phillip L. Wilson; Huaxiong Huang; Shu Takagi

    2008-02-26

    We study a continuum model of the lipid bilayer based on minimizing the free energy of a mixture of water and lipid molecules. This paper extends previous work by Blom & Peletier (2004) in the following ways. (a) It formulates a more physical model of the hydrophobic effect to facilitate connections with microscale simulations. (b) It clarifies the meaning of the model parameters. (c) It outlines a method for determining parameter values so that physically-realistic bilayer density profiles can be obtained, for example for use in macroscale simulations. Points (a)-(c) suggest that the model has potential to robustly connect some micro- and macroscale levels of multiscale blood flow simulations. The mathematical modelling in point (a) is based upon a consideration of the underlying physics of inter-molecular forces. The governing equations thus obtained are minimized by gradient flows via a novel numerical approach; this enables point (b). The numerical results are shown to behave physically in terms of the effect of background concentration, in contrast to the earlier model which is shown here to not display the expected behaviour. A "short-tail" approximation of the lipid molecules also gives an analytical tool which yields critical values of some parameters under certain conditions. Point (c) involves the first quantitative comparison of the numerical data with physical experimental results.

  18. The Molecular Structure of a Phosphatidylserine Bilayer Determined by Scattering and Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    Pan, Jianjun [University of South Florida, Tampa (USF)] [University of South Florida, Tampa (USF); Cheng, Xiaolin [ORNL] [ORNL; Monticelli, Luca [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France] [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France; Heberle, Frederick A [ORNL] [ORNL; Kucerka, Norbert [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,] [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,; Tieleman, D. Peter [University of Calgary, ALberta, Canada] [University of Calgary, ALberta, Canada; Katsaras, John [ORNL] [ORNL

    2014-01-01

    Phosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 A2 at 25 C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger KA than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions.

  19. Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces

    SciTech Connect (OSTI)

    Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

    2008-10-30

    Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

  20. Revealing the Preferred Interlayer Orientations and Stackings of Two-Dimensional Bilayer Gallium Selenide Crystals

    SciTech Connect (OSTI)

    Li, Xufan; Basile Carrasco, Leonardo A; Yoon, Mina; Ma, Cheng; Puretzky, Alexander A; Lee, Jaekwang; Idrobo Tapia, Juan Carlos; Chi, Miaofang; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2015-01-01

    Characterizing and controlling the interlayer orientations and stacking order of bilayer two-dimensional (2D) crystals and van der Waals (vdW) heterostructure is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) that result from different layer stacking provide an ideal platform to study the stacking configurations in bilayer 2D crystals. Here, through a controllable vapor-phase deposition method we selectively grow bilayer GaSe crystals and investigate their two preferred 0 or 60 interlayer rotations. The commensurate stacking configurations (AA and AB-stacking) in as-grown 2D bilayer GaSe crystals are clearly observed at the atomic scale and the Ga-terminated edge structure are identified for the first time by using atomic-resolution scanning transmission electron microscopy (STEM). Theoretical analysis of the interlayer coupling energetics vs. interlayer rotation angle reveals that the experimentally-observed orientations are energetically preferred among the bilayer GaSe crystal polytypes. The combined experimental and theoretical characterization of the GaSe bilayers afforded by these growth studies provide a pathway to reveal the atomistic relationships in interlayer orientations responsible for the electronic and optical properties of bilayer 2D crystals and vdW heterostructures.

  1. Enhanced Biosensing Resolution with Foundry Fabricated Individually Addressable Dual-Gated ISFETs

    E-Print Network [OSTI]

    Bashir, Rashid

    small signals and increase the sensor accuracy when monitoring small pH dynamics in biological reactions reactions into electrical signals.1,2 In an ISFET, the gate region is exposed to an electrolyte, making,8,9 and ISFETs made with metal oxides and polymers are used to monitor biological activity.10

  2. Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

    E-Print Network [OSTI]

    Engel, Jesse H.

    2014-01-01

    Controlled Chemical Doping of Semiconductor Nanocrys- talsHerein, we demonstrate a chemical strategy for the con-dope the nanocrystal solid. Chemical doping methods reported

  3. Passivating overcoat bilayer for multilayer reflective coatings for extreme ultraviolet lithography

    DOE Patents [OSTI]

    Montcalm, Claude (Livermore, CA); Stearns, Daniel G. (Los Altos, CA); Vernon, Stephen P. (Pleasanton, CA)

    1999-01-01

    A passivating overcoat bilayer is used for multilayer reflective coatings for extreme ultraviolet (EUV) or soft x-ray applications to prevent oxidation and corrosion of the multilayer coating, thereby improving the EUV optical performance. The overcoat bilayer comprises a layer of silicon or beryllium underneath at least one top layer of an elemental or a compound material that resists oxidation and corrosion. Materials for the top layer include carbon, palladium, carbides, borides, nitrides, and oxides. The thicknesses of the two layers that make up the overcoat bilayer are optimized to produce the highest reflectance at the wavelength range of operation. Protective overcoat systems comprising three or more layers are also possible.

  4. Nanocrystal doped matrixes

    DOE Patents [OSTI]

    Parce, J. Wallace (Palo Alto, CA); Bernatis, Paul (Sunnyvale, CA); Dubrow, Robert (San Carlos, CA); Freeman, William P. (San Mateo, CA); Gamoras, Joel (Vallejo, CA); Kan, Shihai (San Jose, CA); Meisel, Andreas (Redwood City, CA); Qian, Baixin (Sunnyvale, CA); Whiteford, Jeffery A. (Belmont, CA); Ziebarth, Jonathan (Palo Alto, CA)

    2010-01-12

    Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

  5. Axially Tapered And Bilayer Microchannels For Evaporative Cooling Devices

    DOE Patents [OSTI]

    Nilson, Robert (Cardiff, CA); Griffiths, Stewart (Livermore, CA)

    2005-10-04

    The invention consists of an evaporative cooling device comprising one or more microchannels whose cross section is axially reduced to control the maximum capillary pressure differential between liquid and vapor phases. In one embodiment, the evaporation channels have a rectangular cross section that is reduced in width along a flow path. In another embodiment, channels of fixed width are patterned with an array of microfabricated post-like features such that the feature size and spacing are gradually reduced along the flow path. Other embodiments incorporate bilayer channels consisting of an upper cover plate having a pattern of slots or holes of axially decreasing size and a lower fluid flow layer having channel widths substantially greater than the characteristic microscale dimensions of the patterned cover plate. The small dimensions of the cover plate holes afford large capillary pressure differentials while the larger dimensions of the lower region reduce viscous flow resistance.

  6. Intrinsic Electronic Transport Properties of High-Quality Monolayer and Bilayer MoS[subscript 2

    E-Print Network [OSTI]

    Baugher, Britton W. H.

    We report electronic transport measurements of devices based on monolayers and bilayers of the transition-metal dichalcogenide MoS[subscript 2]. Through a combination of in situ vacuum annealing and electrostatic gating ...

  7. Chirality-Assisted Electronic Cloaking of Confined States in Bilayer Graphene

    E-Print Network [OSTI]

    Gu, Nan

    We show that the strong coupling of pseudospin orientation and charge carrier motion in bilayer graphene has a drastic effect on transport properties of ballistic p-n-p junctions. Electronic states with zero momentum ...

  8. Correlation effects in (111) bilayers of perovskite transition-metal oxides

    SciTech Connect (OSTI)

    Okamoto, Satoshi; Zhu, Wenguang; Nomura, Yusuke; Arita, R.; Xiao, Di; Nagaosa, Naoto

    2014-01-01

    We investigate the correlation-induced Mott, magnetic, and topological phase transitions in artificial (111) bilayers of perovskite transition-metal oxides LaAuO3 and SrIrO3 for which the previous density-functional theory calculations predicted topological insulating states. Using the dynamical-mean-field theory with realistic band structures and Coulomb interactions, LaAuO3 bilayer is shown to be far away from a Mott insulating regime, and a topological-insulating state is robust. On the other hand, SrIrO3 bilayer is on the verge of an orbital-selective topological Mott transition and turns to a trivial insulator by an antiferromagnetic ordering. Oxide bilayers thus provide a novel class of topological materials for which the interplay between the spin-orbit coupling and electron-electron interactions is a fundamental ingredient.

  9. Bilayer graphene growth by low pressure chemical vapor deposition on copper foil

    E-Print Network [OSTI]

    Fang, Wenjing, S.M. Massachusetts Institute of Technology

    2012-01-01

    Successfully integrating graphene in standard processes for applications in electronics relies on the synthesis of high-quality films. In this work we study Low Pressure Chemical Vapor Deposition (LPCVD) growth of bilayer ...

  10. Zone folding effect in Raman G-band intensity of twisted bilayer graphene

    E-Print Network [OSTI]

    Dresselhaus, Mildred

    The G-band Raman intensity is calculated for twisted bilayer graphene as a function of laser excitation energy based on the extended tight binding method. Here we explicitly consider the electron-photon and electron-phonon ...

  11. Polar Kerr Effect and Time Reversal Symmetry Breaking in Bilayer Graphene

    E-Print Network [OSTI]

    Nandkishore, Rahul Mahajan

    The unique sensitivity of optical response to different types of symmetry breaking can be used to detect and identify spontaneously ordered many-body states in bilayer graphene. We predict a strong response at optical ...

  12. Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

    SciTech Connect (OSTI)

    Yun, Minhyuk; Lee, Eunho; Cho, Kilwon; Jeon, Sangmin

    2014-08-18

    A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. The limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20?ppm.

  13. Debonding in bi-layer material systems under moisture effect : a multiscale approach

    E-Print Network [OSTI]

    Lau, Tak-bun, Denvid

    2012-01-01

    Bi-layer material systems are found in various engineering applications ranging from nano-scale components, such as thin films in circuit boards, to macro-scale structures such as adhesive bonding in aerospace and civil ...

  14. pH-sensitive resist materials for combined photolithographic patterning of proteins and fluid lipid bilayers

    E-Print Network [OSTI]

    Shah, Mirat

    2008-01-01

    Photolithography of a pH-sensitive photoresist polymer was performed to pattern both lipid bilayers and proteins onto the same surface. The motivation behind this was to create a substrate mimicking an array of antigen- ...

  15. A p ? n transition for Sn-doped Cu(In,Ga)Se{sub 2} bulk materials

    SciTech Connect (OSTI)

    Monsefi, Mehrdad; Kuo, Dong-Hau, E-mail: dhkuo@mail.ntust.edu.tw

    2013-08-15

    Cu(In,Ga)Se{sub 2} (CIGSe) pellets at different Sn contents were fabricated by reactive liquid-phase sintering at 600–700 °C with the help of sintering aids of Sb{sub 2}S{sub 3} and Te. Powder preparation was based upon the molecular formula of Cu{sub 0.9}[(In{sub 0.7?x}Sn{sub x}Ga{sub 0.3}){sub 0.9}Sb{sub 0.1}](S{sub 0.15}Te{sub 0.2}Se{sub 1.65}) or Sn-x-CIGSe. Morphology, structure, and electrical property of Sn-doped CIGSe bulks were investigated. The composition of Sn-doped CIGSe is purposely designed for studying the doping effect on the CIGSe performance. The unexpected increase in hole concentration of CIGSe due to the donor doping is rationalized. A controllable n-type semiconductor is deliberately achieved for Sn-0.15-CIGSe and important for making a p/n homojunction in CIGSe solar cells. - Graphical abstract: The controls in defect type and electrical properties of Cu(In,Ga)Se{sub 2} by doping Sn{sup 4+} on the In{sup 3+} site. Highlights: • n-type Sn-CIGSe with n{sub e} of 6.4×10{sup 16} cm{sup ?3} and ?{sub e} of 2.3 cm{sup 2}/V s was obtained. • This n-type Sn-CIGSe was obtained by material design and composition control. • The reported n-type CIGSe was obtained from the Zn/CIGSe and CdS/CIGSe bilayers. • Extrinsic donor doping was explored through the results of electrical properties. • A n/p homojunction with Sn-CIGSe and undoped one can be used for solar cell devices.

  16. Micro/nano-patterning of supported lipid bilayers: biophysical studies and membrane-associated species separation 

    E-Print Network [OSTI]

    Shi, Jinjun

    2009-05-15

    -PE/POPC) .................................................. 51 3.5 TIRF image of lipid bilayers-coated microchannel array containing various concentrations of dye-labeled CTB............................................... 54 3.6 UV-Vis spectra of quartz, PDMS, and glass................................................. 58 3.7 Epifluorescence image of 0.1 mol% TR-DHPE/POPC bilayer microaaray with different deep UV exposure time: (a) 0, (b) 30, (c) 120, (d) 180, (e) 300, (f) 450 sec...

  17. Theoretical study on strain induced variations in electronic properties of 2H-MoS{sub 2} bilayer sheets

    SciTech Connect (OSTI)

    Dong, Liang; Dongare, Avinash M.; Namburu, Raju R.; O'Regan, Terrance P.; Dubey, Madan

    2014-02-03

    The strain dependence of the electronic properties of bilayer sheets of 2H-MoS{sub 2} is studied using ab initio simulations based on density functional theory. An indirect band gap for bilayer MoS{sub 2} is observed for all variations of strain along the basal plane. Several transitions for the indirect band gap are observed for various strains for the bilayer structure. The variation of the band gap and the carrier effective masses for the holes and the electrons for the bilayer MoS{sub 2} structure under conditions of uniaxial strain, biaxial strain, as well as uniaxial stress is investigated.

  18. Mechanisms of budding of nanoscale particles through lipid bilayers

    E-Print Network [OSTI]

    Teresa Ruiz-Herrero; Enrique Velasco; Michael F. Hagan

    2012-02-21

    We examine the budding of a nanoscale particle through a lipid bilayer using molecular dynamics simulations, free energy calculations, and an elastic theory, with the aim of determining the extent to which equilibrium elasticity theory can describe the factors that control the mechanism and efficiency of budding. The particle is a smooth sphere which experiences attractive interactions to the lipid head groups. Depending on the parameters, we observe four classes of dynamical trajectories: particle adhesion to the membrane, stalled partially wrapped states, budding followed by scission, and membrane rupture. In most regions of parameter space we find that the elastic theory agrees nearly quantitatively with the simulated phase behavior as a function of adhesion strength, membrane bending rigidity, and particle radius. However, at parameter values near the transition between particle adhesion and budding, we observe long-lived partially wrapped states which are not captured by existing elastic theories. These states could constrain the accessible system parameters for those enveloped viruses or drug delivery vehicles which rely on exo- or endocytosis for membrane transport.

  19. Method of doping a semiconductor

    DOE Patents [OSTI]

    Yang, Chiang Y. (Miller Place, NY); Rapp, Robert A. (Columbus, OH)

    1983-01-01

    A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

  20. Bilayer Polymer Solar Cells with Improved Power Conversion Efficiency and Enhanced Spectrum Coverage

    SciTech Connect (OSTI)

    Kekuda, Dhananjaya [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal, India 576 104 (India); Chu, Chih-Wei [Research Center for Applied Science, Academia Sinica, Taipei, Taiwan 300 13 (China)

    2011-10-20

    We demonstrate the construction of an efficient bilayer polymer solar cell comprising of Poly(3-hexylthiophene)(P3HT) as a p-type semiconductor and asymmetric fullerene (C{sub 70}) as n-type counterparts. The bilayer configuration was very efficient compared to the individual layer performance and it behaved like a regular p-n junction device. The photovoltaic characteristic of the bilayers were studied under AM 1.5 solar radiation and the optimized device parameters are the following: Voc = 0.5V, Jsc = 10.1 mA/cm{sup 2}, FF = 0.60 and power conversion efficiency of 3.6 %. A high fill factor of {approx}0.6 was achieved, which is only slightly reduced at very intense illumination. Balanced mobility between p-and n-layers is achieved which is essential for achieving high device performance. Correlation between the crystallinity, morphology and the transport properties of the active layers is established. The External quantum efficiency (EQE) spectral distribution of the bilayer devices with different processing solvents correlates well with the trends of short circuit current densities (J{sub sc}) measured under illumination. Efficiency of the bilayer devices with rough P3HT layer was found to be about 3 times higher than those with a planar P3HT surface. Hence it is desirable to have a larger grains with a rough surface of P3HT layer for providing larger interfacial area for the exciton dissociation.

  1. Nanoporous microbead supported bilayers: stability, physical characterization, and incorporation of functional transmembrane proteins.

    SciTech Connect (OSTI)

    Davis, Ryan W. (University of New Mexico, Albuquerque, NM); Brozik, James A. (University of New Mexico, Albuquerque, NM); Brozik, Susan Marie; Cox, Jason M.; Lopez, Gabriel P.; Barrick, Todd A.; Flores, Adrean

    2007-03-01

    The introduction of functional transmembrane proteins into supported bilayer-based biomimetic systems presents a significant challenge for biophysics. Among the various methods for producing supported bilayers, liposomal fusion offers a versatile method for the introduction of membrane proteins into supported bilayers on a variety of substrates. In this study, the properties of protein containing unilamellar phosphocholine lipid bilayers on nanoporous silica microspheres are investigated. The effects of the silica substrate, pore structure, and the substrate curvature on the stability of the membrane and the functionality of the membrane protein are determined. Supported bilayers on porous silica microspheres show a significant increase in surface area on surfaces with structures in excess of 10 nm as well as an overall decrease in stability resulting from increasing pore size and curvature. Comparison of the liposomal and detergent-mediated introduction of purified bacteriorhodopsin (bR) and the human type 3 serotonin receptor (5HT3R) are investigated focusing on the resulting protein function, diffusion, orientation, and incorporation efficiency. In both cases, functional proteins are observed; however, the reconstitution efficiency and orientation selectivity are significantly enhanced through detergent-mediated protein reconstitution. The results of these experiments provide a basis for bulk ionic and fluorescent dye-based compartmentalization assays as well as single-molecule optical and single-channel electrochemical interrogation of transmembrane proteins in a biomimetic platform.

  2. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-06-03

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whosemore »primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y« less

  3. Comparing Simulations of Lipid Bilayers to Scattering Data: The GROMOS 43A1-S3 Force Field

    E-Print Network [OSTI]

    Nagle, John F.

    , and excellent, fit to neutron scattering data occurs at an interpolated AN = 66.6 Å2 and the best lipid bilayers. It was not, however, compared to neutron scattering data which has become particularlyComparing Simulations of Lipid Bilayers to Scattering Data: The GROMOS 43A1-S3 Force Field Anthony

  4. Anisotropic Motion and Molecular Dynamics of Cholesterol, Lanosterol, and Ergosterol in Lecithin Bilayers Studied by Quasi-elastic Neutron Scattering

    E-Print Network [OSTI]

    Brown, Michael F.

    Bilayers Studied by Quasi-elastic Neutron Scattering Emil Endress, Helmut Heller,§ He´le`ne CasaltaVised Manuscript ReceiVed June 27, 2002 ABSTRACT: Quasi-elastic neutron scattering (QENS) was employed to study of motion within the bilayer on the molecular dynamics time scale. In a recent quasi-elastic neutron

  5. Method of doping organic semiconductors

    DOE Patents [OSTI]

    Kloc, Christian Leo (Constance, DE); Ramirez, Arthur Penn (Summit, NJ); So, Woo-Young (New Providence, NJ)

    2012-02-28

    A method includes the steps of forming a contiguous semiconducting region and heating the region. The semiconducting region includes polyaromatic molecules. The heating raises the semiconducting region to a temperature above room temperature. The heating is performed in the presence of a dopant gas and the absence of light to form a doped organic semiconducting region.

  6. Air-stable droplet interface bilayers on oil-infused surfaces

    SciTech Connect (OSTI)

    Boreyko, Jonathan B [ORNL] [ORNL; Polizos, Georgios [Oak Ridge National Laboratory (ORNL)] [Oak Ridge National Laboratory (ORNL); Datskos, Panos G [ORNL] [ORNL; Sarles, Stephen A [ORNL] [ORNL; Collier, Pat [ORNL] [ORNL

    2014-01-01

    Droplet interface bilayers (DIBs) are versatile model membranes useful for synthetic biology and biosensing; however, to date they have always been confined to fluid reservoirs. Here, we demonstrate that when two or more water droplets collide on an oil-infused substrate, they exhibit non-coalescence due to the formation of a thin oil film that gets squeezed between the droplets from the bottom-up. We show that when phospholipids are included in the water droplets, a stable droplet interface bilayer forms between the non-coalescing water droplets. As with traditional oil-submerged DIBs, we were able to characterize ion channel transport by incorporating peptides into each droplet. Our findings reveal that droplet interface bilayers can function in air environments, which could potentially enable biosensing of atmospheric particulates.

  7. Controlling interactions in supported bilayers from weak electrostatic repulsion to high osmotic pressure

    E-Print Network [OSTI]

    Hemmerle, Arnaud; Charitat, Thierry; Lecuyer, Sigolène; Fragneto, Giovanna; Daillant, Jean; 10.1073/pnas.1211669109

    2013-01-01

    Understanding interactions between membranes requires measurements on well-controlled systems close to natural conditions, in which fluctuations play an important role. We have determined, by grazing incidence X-ray scattering, the interaction potential between two lipid bilayers, one adsorbed on a solid surface and the other floating close by. We find that interactions in this highly hydrated model system are two orders of magnitude softer than in previously reported work on multilayer stacks. This is attributed to the weak electrostatic repulsion due to the small fraction of ionized lipids in supported bilayers with a lower number of defects. Our data are consistent with the Poisson-Boltzmann theory, in the regime where repulsion is dominated by the entropy of counter ions. We also have unique access to very weak entropic repulsion potentials, which allowed us to discriminate between the various models proposed in the literature. We further demonstrate that the interaction potential between supported bilaye...

  8. Chiral tunneling through generic one-dimensional potential barriers in bilayer graphene

    E-Print Network [OSTI]

    V. Kleptsyn; A. Okunev; I. Schurov; D. Zubov; M. I. Katsnelson

    2015-07-28

    We study tunneling of charge carriers in single- and bilayer graphene. We propose an explanation for non-zero "magic angles" with 100% transmission for the case of symmetric potential barrier, as well as for their almost-survival for slightly asymmetric barrier in the bilayer graphene known previously from numerical simulations. Most importantly, we demonstrate that these magic angles are not protected in the case of bilayer and give an explicit example of a barrier with very small electron transmission probability for any angles. This means that one can lock charge carriers by a p-n-p (or n-p-n) junction without opening energy gap. This creates new opportunities for the construction of graphene transistors.

  9. Dynamics of an asymmetric bilayer lipid membrane in a viscous solvent

    E-Print Network [OSTI]

    Bingham, R J; Olmsted, P D

    2015-01-01

    Bilayer lipid membranes (BLMs) are an essential component of many biological systems, forming a functional barrier between the cell and the surrounding environment. When the membrane relaxes from a structural perturbation, the dynamics of the relaxation depends on the bilayer structure. We present a model of a BLM in a viscous solvent, including an explicit description of a 'thick' membrane, where the fluctuations in the thickness of a monolayer leaflet are coupled to changes in the lipid density within that monolayer. We find dispersion relations describing three intuitive forms of bilayer motion, including a mode describing motion of the intermonolayer surface not noted previously in the literature. Two intrinsic length scales emerge that help characterise the dynamics; the well known Saffman-Delbruck length and another, $\\ell_r$, resulting from the intermonolayer friction. The framework also allows for asymmetry in the BLM parameters between the monolayer leaflets, which is found to couple dynamic modes of...

  10. Transfer matrix theory of monolayer graphene/bilayer graphene heterostructure superlattice

    SciTech Connect (OSTI)

    Wang, Yu

    2014-10-28

    We have formulated a transfer matrix method to investigate electronic properties of graphene heterostructure consisting of monolayer graphene and bilayer counterpart. By evaluating transmission, conductance, and band dispersion, we show that, irrespective of the different carrier chiralities in monolayer graphene and bilayer graphene, superlattice consisting of biased bilayer graphene barrier and monolayer graphene well can mimic the electronic properties of conventional semiconductor superlattice, displaying the extended subbands in the quantum tunneling regime and producing anisotropic minigaps for the classically allowed transport. Due to the lateral confinement, the lowest mode has shifted away from the charge neutral point of monolayer graphene component, opening a sizeable gap in concerned structure. Following the gate-field and geometry modulation, all electronic states and gaps between them can be externally engineered in an electric-controllable strategy.

  11. Direct measurement of DNA-mediated adhesion between lipid bilayers

    E-Print Network [OSTI]

    S. F. Shimobayashi; B. M. Mognetti; L. Parolini; D. Orsi; P. Cicuta; L. Di Michele

    2015-04-16

    Multivalent interactions between deformable mesoscopic units are ubiquitous in biology, where membrane macromolecules mediate the interactions between neighbouring living cells and between cells and solid substrates. Lately, analogous artificial materials have been synthesised by functionalising the outer surface of compliant Brownian units, for example emulsion droplets and lipid vesicles, with selective linkers, in particular short DNA sequences. This development extended the range of applicability of DNA as a selective glue, originally applied to solid nano and colloidal particles. On very deformable lipid vesicles, the coupling between statistical effects of multivalent interactions and mechanical deformation of the membranes gives rise to complex emergent behaviours, as we recently contributed to demonstrate [Parolini et al., Nature Communications, 2015, 6, 5948]. Several aspects of the complex phenomenology observed in these systems still lack a quantitative experimental characterisation and fundamental understanding. Here we focus on the DNA-mediated multivalent interactions of a single liposome adhering to a flat supported bilayer. This simplified geometry enables the estimate of the membrane tension induced by the DNA-mediated adhesive forces acting on the liposome. Our experimental investigation is completed by morphological measurements and the characterisation of the DNA-melting transition, probed by in-situ F\\"{o}rster Resonant Energy Transfer spectroscopy. Experimental results are compared with the predictions of an analytical theory that couples the deformation of the vesicle to a full description of the statistical mechanics of mobile linkers. With at most one fitting parameter, our theory is capable of semi-quantitatively matching experimental data, confirming the quality of the underlying assumptions.

  12. Vapor deposition of water on graphitic surfaces: Formation of amorphous ice, bilayer ice, ice I, and liquid water

    SciTech Connect (OSTI)

    Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria

    2014-11-14

    Carbonaceous surfaces are a major source of atmospheric particles and could play an important role in the formation of ice. Here we investigate through molecular simulations the stability, metastability, and molecular pathways of deposition of amorphous ice, bilayer ice, and ice I from water vapor on graphitic and atomless Lennard-Jones surfaces as a function of temperature. We find that bilayer ice is the most stable ice polymorph for small cluster sizes, nevertheless it can grow metastable well above its region of thermodynamic stability. In agreement with experiments, the simulations predict that on increasing temperature the outcome of water deposition is amorphous ice, bilayer ice, ice I, and liquid water. The deposition nucleation of bilayer ice and ice I is preceded by the formation of small liquid clusters, which have two wetting states: bilayer pancake-like (wetting) at small cluster size and droplet-like (non-wetting) at larger cluster size. The wetting state of liquid clusters determines which ice polymorph is nucleated: bilayer ice nucleates from wetting bilayer liquid clusters and ice I from non-wetting liquid clusters. The maximum temperature for nucleation of bilayer ice on flat surfaces, T{sub B}{sup max} is given by the maximum temperature for which liquid water clusters reach the equilibrium melting line of bilayer ice as wetting bilayer clusters. Increasing water-surface attraction stabilizes the pancake-like wetting state of liquid clusters leading to larger T{sub B}{sup max} for the flat non-hydrogen bonding surfaces of this study. The findings of this study should be of relevance for the understanding of ice formation by deposition mode on carbonaceous atmospheric particles, including soot.

  13. Transport properties in bilayer Quantum Hall systems in the presence of a topological defect

    E-Print Network [OSTI]

    Gerardo Cristofano; Vincenzo Marotta; Adele Naddeo; Giuliano Niccoli

    2006-06-27

    Following a suggestion given in Phys. Lett. B 571(2003) 621, we show how a bilayer Quantum Hall system at fillings nu =1/p+1 can exhibit a point-like topological defect in its edge state structure. Indeed our CFT theory for such a system, the Twisted Model (TM), gives rise in a natural way to such a feature in the twisted sector. Our results are in agreement with recent experimental findings (Phys. Rev. B 72 (2005) 041305) which evidence the presence of a topological defect in the transport properties of the bilayer system.

  14. Kinetics of an Inverse Temperature Transition Process and Its Application on Supported Lipid Bilayer 

    E-Print Network [OSTI]

    Chang, Chin-Yuan

    2011-10-21

    (ethylene glycol)11 (PEG) so that the conformation of the PEG is controlled by its density on the bilayer surface. In low density, the PEG is in mushroom conformation so the IgG in bulk solution can access the biotin on the membrane surface. As density... of the PEG goes higher than the transition density, the PEG undergoes a mushroom-to-brush transition and the access of IgG to biotin will be blocked by the brush-like PEG on bilayer surface. An advanced design is presented here that the conformations...

  15. Phosphorous doping a semiconductor particle

    DOE Patents [OSTI]

    Stevens, Gary Don (18912 Ravenglen Ct, Dallas, TX 75287); Reynolds, Jeffrey Scott (703 Horizon, Murphy, TX 75094)

    1999-07-20

    A method (10) of phosphorus doping a semiconductor particle using ammonium phosphate. A p-doped silicon sphere is mixed with a diluted solution of ammonium phosphate having a predetermined concentration. These spheres are dried (16, 18), with the phosphorus then being diffused (20) into the sphere to create either a shallow or deep p-n junction. A good PSG glass layer is formed on the surface of the sphere during the diffusion process. A subsequent segregation anneal process is utilized to strip metal impurities from near the p-n junction into the glass layer. A subsequent HF strip procedure is then utilized to removed the PSG layer. Ammonium phosphate is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirement.

  16. Phosphorus doping a semiconductor particle

    DOE Patents [OSTI]

    Stevens, G.D.; Reynolds, J.S.

    1999-07-20

    A method of phosphorus doping a semiconductor particle using ammonium phosphate is disclosed. A p-doped silicon sphere is mixed with a diluted solution of ammonium phosphate having a predetermined concentration. These spheres are dried with the phosphorus then being diffused into the sphere to create either a shallow or deep p-n junction. A good PSG glass layer is formed on the surface of the sphere during the diffusion process. A subsequent segregation anneal process is utilized to strip metal impurities from near the p-n junction into the glass layer. A subsequent HF strip procedure is then utilized to removed the PSG layer. Ammonium phosphate is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirement. 1 fig.

  17. Degenerate doping of metallic anodes

    SciTech Connect (OSTI)

    Friesen, Cody A; Zeller, Robert A; Johnson, Paul B; Switzer, Elise E

    2015-05-12

    Embodiments of the invention relate to an electrochemical cell comprising: (i) a fuel electrode comprising a metal fuel, (ii) a positive electrode, (iii) an ionically conductive medium, and (iv) a dopant; the electrodes being operable in a discharge mode wherein the metal fuel is oxidized at the fuel electrode and the dopant increases the conductivity of the metal fuel oxidation product. In an embodiment, the oxidation product comprises an oxide of the metal fuel which is doped degenerately. In an embodiment, the positive electrode is an air electrode that absorbs gaseous oxygen, wherein during discharge mode, oxygen is reduced at the air electrode. Embodiments of the invention also relate to methods of producing an electrode comprising a metal and a doped metal oxidation product.

  18. Lanthanide doped strontium barium mixed halide scintillators

    DOE Patents [OSTI]

    Gundiah, Gautam; Bizarri, Gregory; Hanrahan, Stephen M; Bourret-Courchesne, Edith; Derenzo, Stephen E

    2013-07-16

    The present invention provides for a composition comprising an inorganic scintillator comprising a lanthanide-doped strontium barium mixed halide useful for detecting nuclear material.

  19. Lanthanide doped barium phosphorous oxide scintillators

    DOE Patents [OSTI]

    Borade, Ramesh B; Bourret-Courchesne, Edith; Denzo, Stephen E

    2013-02-26

    The present invention provides for a composition comprising an inorganic scintillator comprising a lanthanide-doped barium phosphorous oxide useful for detecting nuclear material.

  20. Acid Doped Membranes for High Temperature PEMFC

    Broader source: Energy.gov [DOE]

    Presentation on Acid Doped Membranes for High Temperature PEMFC to the High Temperature Membrane Working Group, May 25, 2004 in Philadelphia, PA.

  1. Investigation of the effect of bilayer membrane structures and fluctuation amplitudes on SANS/SAXS profile for short membrane wavelength

    SciTech Connect (OSTI)

    Lee, Victor; Hawa, Takumi [School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, Oklahoma 73019 (United States)] [School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2013-09-28

    The effect of bilayer membrane structures and fluctuation amplitudes on small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) profile is investigated based on harmonic motions of the surfactant bilayers with bending as well as thickness fluctuation motions. In this study we consider the case in which the wavelength of the bilayer membrane is shorter than the thickness of the membrane. We find that the thickness of the surfactant bilayer membrane, d{sub m}, affects both q{sub dip} and q{sub peak} of I(q,0) profile, and that the fluctuation amplitude, a, of the membrane changes the peak of I(q,0). A simple formula is derived to estimate the thickness of the bilayer based on the q{sub dip} of the profile obtained from the simulation. The resulting estimates of the thickness of the bilayer with harmonic motion showed accuracy within 1%. Moreover, the bilayer thicknesses estimated from the proposed formula show an excellent agreement with the SANS and SAXS experimental results available in the literatures. We also propose a curve fit model, which describes the relationship between the fluctuation amplitude and the normalized q{sub peak} ratio. The present results show the feasibility of the simple formula to estimate the fluctuation amplitude based on the SANS and SAXS profiles.

  2. Supplementary Material for Interdroplet bilayer arrays in millifluidic droplet traps from 3D printed moulds

    E-Print Network [OSTI]

    Southampton, University of

    on an Objet Connex350TM 3D printer. One block was baked for 24 hours at 80 °C, causing a colour change fromSupplementary Material for Interdroplet bilayer arrays in millifluidic droplet traps from 3D. Untreated 3D-printed moulds were found to inhibit the curing of PDMS; baking the moulds eliminates

  3. Control of membrane permeability in air-stable droplet interface bilayers

    SciTech Connect (OSTI)

    Mruetusatorn, Prachya [ORNL; Polizos, Georgios [Oak Ridge National Laboratory (ORNL); Datskos, Panos G [ORNL; Taylor, Graham [University of Tennessee (UT); Sarles, Stephen A [ORNL; Boreyko, Jonathan [Virginia Polytechnic Institute and State University; Hayes, Douglas G [ORNL; Collier, Pat [ORNL

    2015-01-01

    Air-stable droplet interface bilayers (airDIBs) on oil-infused surfaces are versatile model membranes for synthetic biology applications, including biosensing of airborne species. However, air-DIBs are subject to evaporation, which can, over time, destabilize them and reduce their useful lifetime compared to traditional DIBs that are fully submerged in oil. Here, we show that lifetimes of air-DIBs can be extended by as much as an order of magnitude by maintaining them at a temperature just above the dew point. We find that raising the temperature from near the dew point (7 C at 38.5 % relative humidity) to room temperature results in loss of water molecules of hydration from the polar head groups of the lipid bilayer membrane due to evaporation in an irreversible process that increases the overall entropy of the system. This dehydration transition affects primarily the bilayer resistance, by increasing ion permeability through the increasingly disordered polar head group region of the bilayer. Temperature and/or relative humidity are conveniently tunable parameters for controlling the stability and composition of air-DIBs membranes, while still allowing for operation in ambient environments.

  4. SUPPLEMENTARY MATERIAL Lipid bilayer structure determined by the simultaneous analysis of neutron

    E-Print Network [OSTI]

    Nagle, John F.

    scattering intensities I(q) for both neutrons and x-rays using )()()()( qPqPqIqF TSLC= , (1.) where PLC in structure between oriented and spherical bilayers experimentally using both neutron and x-ray scattering in (2). Our study concluded no difference between the two for x-ray and neutron scattering data

  5. An Experiment-Based Algorithm for Predicting the Partitioning of Unfolded Peptides into Phosphatidylcholine Bilayer Interfaces

    E-Print Network [OSTI]

    White, Stephen

    into Phosphatidylcholine Bilayer Interfaces Kalina Hristova and Stephen H. White*,§ Department of Physiology and Biophysics interfaces and n-octanol. A simplified version of the thermodynamic (4) cycle that forms the quantitative for the complete cycle opens the way for predicting the partitioning and se- condary structure of membrane

  6. Raman spectra of out-of-plane phonons in bilayer graphene

    E-Print Network [OSTI]

    Sato, Kentaro

    The double resonance Raman spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of ...

  7. Atomic Force Microscopy Studies of Lipophosphoglycan (LPG) Molecules in Lipid Bilayers

    SciTech Connect (OSTI)

    LAST, JULIE A.; HUBER, TINA; SASAKI, DARRYL Y.; SALVATORE, BRIAN; TURCO, SALVATORE J.

    2003-03-01

    Lipophosphoglycan (LPG) is a lypopolysaccharide found on the surface of the parasite Leishmania donovani that is thought to play an essential role in the infection of humans with leishamniasis. LPG acts as an adhesion point for the parasite to the gut of the sand fly, whose bite is responsible for transmitting the disease. In addition, LPG acts to inhibit protein kinase C (PKC) in the human macrophage, possibly by structural changes in the membrane. The Ca{sup 2+} ion is believed to play a role in the infection cycle, acting both as a crosslinker between LPG molecules and by playing a part in modulating PKC activity. To gain insight into the structure of LPG within a supported lipid membrane and into the structural changes that occur due to Ca{sup 2+} ions, we have employed the atomic force microscope (AFM). We have observed that the LPG molecules inhibit bilayer fusion, resulting in bilayer islands on the mica surface. One experiment suggests that the LPG molecules are parallel to the mica surface and that the structure of the LPG changes upon addition of Ca{sup 2+}, with an increase in the height of the LPG molecules from the bilayer surface and an almost complete coverage of LPG on the bilayer island.

  8. Bilayer-Spanning DNA Nanopores with Voltage-Switching between Open and Closed State

    E-Print Network [OSTI]

    Seifert, Astrid; Göpfrich, Kerstin; Burns, Jonathan R.; Fertig, Niels; Keyser, Ulrich F.; Howorka, Stefan

    2014-10-22

    competing model in which ions pass solely through a suggested gap between lipid bilayer and pore; a membrane hole this size would not be energe- tically stable for our minute-long measurement times used in our PEG sizing experiments. However, it cannot...

  9. Detection of atomic spin labels in a lipid bilayer using a single-spin nanodiamond probe

    E-Print Network [OSTI]

    Scholten, Robert

    Detection of atomic spin labels in a lipid bilayer using a single-spin nanodiamond probe Stefan conditions using a single-spin nanodiamond sensor. Changes in the spin relaxation time of the sensor located in a nanodiamond­­which is situated in the target structure itself and acts as a nanoscopic magnetic field detector

  10. Proteins with H-bond packing defects are highly interactive with lipid bilayers: Implications

    E-Print Network [OSTI]

    Berry, R. Stephen

    Proteins with H-bond packing defects are highly interactive with lipid bilayers: Implications of Chicago, Chicago, IL 60637; Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka-related amyloidogenic proteins and espe- cially cellular prion proteins have the highest proportion of incom- pletely

  11. Growth of Single- and Bilayer ZnO on Au(111) and Interaction with Copper

    SciTech Connect (OSTI)

    Deng, Xingyi; Yao, Kun; Sun, Keju; Li, Wei-Xue; Lee, Junseok; Matranga, Christopher

    2013-05-30

    The stoichiometric single- and bi-layer ZnO(0001) have been prepared by reactive deposition of Zn on Au(111) and studied in detail with X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations. Both single- and bi-layer ZnO(0001) adopt a planar, graphite-like structure similar to freestanding ZnO(0001) due to the weak van der Waals interactions dominating their adhesion with the Au(111) substrate. At higher temperature, the single-layer ZnO(0001) converts gradually to bi-layer ZnO(0001) due to the twice stronger interaction between two ZnO layers than the interfacial adhesion of ZnO with Au substrate. It is found that Cu atoms on the surface of bi-layer ZnO(0001) are mobile with a diffusion barrier of 0.31 eV, and likely to agglomerate and form nanosized particles at low coverages; while Cu atoms tend to penetrate a single layer of ZnO(0001) with a barrier of 0.10 eV, resulting in a Cu free surface.

  12. Development of a Microfluidic Device for Synthesis of Lipid Bi-Layer In-Situ 

    E-Print Network [OSTI]

    Banneyake, Bm U.

    2010-01-14

    , is thinned to form a lipid bi-layer by a continuous flow of buffer solution on both sides of the aperture in the microfluidic device. The microfluidic device is expected to have advantages from its compact design. Further, the new approach is expected...

  13. Complete Bilayer Adsorption Of C16TAB On The Surface Of Mica Using Neutron Reflection

    E-Print Network [OSTI]

    Griffin, L. R.; Browning, K. L.; Truscott, C. L.; Clifton, L. A.; Clarke, S. M.

    2015-05-05

    In this work we present neutron reflection data from an alkylammonium surfactant (C16TAB) at the mica/water interface. The system is studied in situ in a non-invasive manner and indicates the formation of a complete adsorbed bilayer with little...

  14. NEUTRON SCATTERING SHOWS THAT CYTOCHROME b5 PENETRATES DEEPLY INTO THE LIPID BILAYER

    E-Print Network [OSTI]

    NEUTRON SCATTERING SHOWS THAT CYTOCHROME b5 PENETRATES DEEPLY INTO THE LIPID BILAYER E. P. GOGOL of a highly deuterated phospholipid. Small-angle neutron diffraction patterns were collected in a series of H to lipid vesicles using neutron small-angle scattering methods. To increase scat- tering contrast between

  15. Theory of carrier transport in bilayer graphene S. Das Sarma, E. H. Hwang, and E. Rossi

    E-Print Network [OSTI]

    Rossi, Enrico

    properties of massless, gapless, and chiral Dirac particles in two- dimensional 2D single-layer graphene SLG attention over the last few years. More recently, however, carrier transport in 2D bilayer graphene BLG has of electrons holes in the graphene con- duction valence band with the system being a zero-gap semiconductor

  16. Formation and Transport of Correlated Electronic States at Room Temperature in Graphene Bilayers

    E-Print Network [OSTI]

    Shumway, John

    -hole bilayer graphene at spontaneous coherence using novel path integral Monte Carlo and Green's function based a sharply peaked differential tunneling conductance and quasiparticle paths which wind around our solution predicted to occur in thin films made from topological insulators (3). Here we will discuss the calculation

  17. Modified Timoshenko formula for bending of ultrathin strained bilayer films Ji Zang and Feng Liua

    E-Print Network [OSTI]

    Simons, Jack

    - tions, such as coating, epitaxial growth of thin films, and device interconnection.3­7 Recently, classical Timoshenko formula has been used to calculate the bending curvature or radius of rolledAs/InAs nano- tubes from rolling up released GaAs/InAs bilayer films of only a few MLs thick.11 Nanotubes

  18. Role of Microstructure and Doping on the Mechanical Properties...

    Office of Scientific and Technical Information (OSTI)

    Role of Microstructure and Doping on the Mechanical Properties of Polysilicon Thin Films. Citation Details In-Document Search Title: Role of Microstructure and Doping on the...

  19. Micro-patterning of ionic reservoirs within a double bilayer lipid membrane to fabricate a 2D array of ion-channel switch based electrochemical biosensors

    SciTech Connect (OSTI)

    Sansinena, J. M.; Yee, C. K.; Sapuri, A.; Swanson, Basil I.; Redondo, A.; Parikh, A. N.

    2004-01-01

    We present a simple approach for the design of ionic reservoir arrays within a double phospholipid bilayer to ultimately develop a 2D array of ion-channel switch based electrochemical biosensors. As a first step, a primary bilayer lipid membrane is deposited onto an array of electrodes patterned onto a substrate surface. Subsequently, an array of microvoids is created within the bilayer by a wet photolithographic patterning of phospholipid bilayers using a deep UV light source and a quartz/chrome photomask. To ensure registry, the photomask used to pattern bilayers is designed to match up the microvoids within the primary bilayer with the array of electrodes on the substrate surface. The deposition of a secondary bilayer lipid membrane onto the primary bilayer that spans across the patterned microvoids leads to the formation of the array of ionic reservoirs within the double phospholipid bilayer. This is accomplished using giant unilamellar vesicles and by exploiting membrane electrostatics. The use of ion-channels incorporated into the secondary bilayer that covers the individual ionic reservoirs allows the construction of a 2D array of ion-channel switch based electrochemical biosensors that are able to recognize different target-agents simultaneously.

  20. PHYSICAL REVIEW B 85, 195412 (2012) Bias-dependent D'yakonov-Perel' spin relaxation in bilayer graphene

    E-Print Network [OSTI]

    2012-01-01

    with an Elliot- Yafet-type mechanism was identified.6 Subsequent experi- ments appear to have confirmed to a few nanoseconds at 4 K were found in bilayer graphene.8,9 Following these experiments both the Elliot

  1. Influence of protein and lipid domains on the structure, fluidity and phase behavior of lipid bilayer membranes

    E-Print Network [OSTI]

    Horton, Margaret R. (Margaret Ruth)

    2007-01-01

    The lipid bilayer forms the basic structure of the cell membrane, which is a heterogeneous matrix of proteins and lipids that provides a barrier between the interior of a cell and its outside environment. Protein and lipid ...

  2. Mass-related inversion symmetry breaking and phonon self-energy renormalization in isotopically labeled AB-stacked bilayer graphene

    E-Print Network [OSTI]

    Araujo, Paulo Antonio Trinidade

    A mass-related symmetry breaking in isotopically labeled bilayer graphene (2LG) was investigated during in-situ electrochemical charging of AB stacked (AB-2LG) and turbostratic (t-2LG) layers. The overlap of the two ...

  3. Linker-free grafting of fluorinated polymeric cross-linked network bilayers for durable reduction of ice adhesion

    E-Print Network [OSTI]

    Sojoudi, Hossein

    Thin films of bilayer poly(divinyl benzene) p(DVB)/poly(perfluorodecylacrylate) (p-PFDA) are synthesized via iCVD on steel and silicon substrates. Nanomechanical measurements reveal that the elastic modulus and hardness ...

  4. Potential commercial application of a bi-layer bone-ligament regeneration scaffold to anterior cruciate ligament replacement

    E-Print Network [OSTI]

    Li, Jessica C. (Jessica Ching-Yi)

    2006-01-01

    A business model was created in order to explore the commercial application of a bi-layer bone-ligament scaffold to the treatment of torn anterior cruciate ligaments (ACL) requiring replacement. The two main keys in producing ...

  5. Does water dope carbon nanotubes?

    SciTech Connect (OSTI)

    Bell, Robert A.; Payne, Michael C.; Mostofi, Arash A.

    2014-10-28

    We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 Å, highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10{sup ?4}?e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.

  6. The effect of spin-orbit coupling in band structure and edge states of bilayer graphene

    SciTech Connect (OSTI)

    Sahdan, Muhammad Fauzi; Darma, Yudi

    2015-04-16

    Topological insulators are predicted to be useful ranging from spintronics to quantum computation. Graphene was first predicted to be the precursor of topological insulator by Kane-Mele. They developed a Hamiltonian model to describe the gap opening in graphene. In this work, we investigate the band structure of bilayer grapheme and also its edge states by using this model with analytical approach. The results of our calculation show that the gap opening occurs at K and K’ point in bilayer graphene.In addition, a pair of gapless edge modes occurs both in the zigzag and arm-chair configurations are no longer exist. There are gap created at the edge even though thery are very small.

  7. Magnetoelectric effects and valley-controlled spin quantum gates in transition metal dichalcogenide bilayers

    SciTech Connect (OSTI)

    Gong, Zhirui; Liu, G. B.; Yu, Hongyi; Xiao, Di; Cui, Xiaodong; Xu, Xiaodong; Yao, Wang

    2013-01-01

    In monolayer group-VI transition metal dichalcogenides, charge carriers have spin and valley degrees of freedom, both associated with magnetic moments. On the other hand, the layer degree of freedom in multilayers is associated with electrical polarization. Here we show that transition metal dichalcogenide bilayers offer an unprecedented platform to realize a strong coupling between the spin, valley and layer pseudospin of holes. Such coupling gives rise to the spin Hall effect and spin-dependent selection rule for optical transitions in inversion symmetric bilayer and leads to a variety of magnetoelectric effects permitting quantum manipulation of these electronic degrees of freedom. Oscillating electric and magnetic fields can both drive the hole spin resonance where the two fields have valley-dependent interference, making an interplay between the spin and valley as information carriers possible for potential valley-spintronic applications. We show how to realize quantum gates on the spin qubit controlled by the valley bit.

  8. Highly efficient terahertz wave modulators by photo-excitation of organics/silicon bilayers

    SciTech Connect (OSTI)

    Yoo, Hyung Keun; Kang, Chul; Hwang, In-Wook; Yoon, Youngwoon; Lee, Kiejin; Kee, Chul-Sik; Lee, Joong Wook

    2014-07-07

    Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C{sub 60}/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C{sub 60} layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.

  9. Electron dynamics of the buffer layer and bilayer graphene on SiC

    SciTech Connect (OSTI)

    Shearer, Alex J.; Caplins, Benjamin W.; Suich, David E.; Harris, Charles B., E-mail: cbharris@berkeley.edu [Department of Chemistry, University of California at Berkeley, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Johns, James E. [Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455 (United States); Hersam, Mark C. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States)

    2014-06-09

    Angle- and time-resolved two-photon photoemission (TPPE) was used to investigate electronic states in the buffer layer of 4H-SiC(0001). An image potential state (IPS) series was observed on this strongly surface-bound buffer layer, and dispersion measurements indicated free-electron-like behavior for all states in this series. These results were compared with TPPE taken on bilayer graphene, which also show the existence of a free-electron-like IPS series. Lifetimes for the n?=?2, and n?=?3 states were obtained from time-resolved TPPE; slightly increased lifetimes were observed in the bilayer graphene sample for the n?=?2 the n?=?3 states. Despite the large band gap of graphene at the center of the Brillouin zone, the lifetime results demonstrate that the graphene layers do not behave as a simple tunneling barrier, suggesting that the buffer layer and graphene overlayers play a direct role in the decay of IPS electrons.

  10. Microwave-induced spin currents in ferromagnetic-insulator|normal-metal bilayer system

    SciTech Connect (OSTI)

    Agrawal, Milan, E-mail: magrawal@physik.uni-kl.de [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany); Graduate School Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern (Germany); Serga, Alexander A.; Lauer, Viktor; Papaioannou, Evangelos Th.; Hillebrands, Burkard; Vasyuchka, Vitaliy I. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany)

    2014-09-01

    A microwave technique is employed to simultaneously examine the spin pumping and the spin Seebeck effect processes in a YIG|Pt bilayer system. The experimental results show that for these two processes, the spin current flows in opposite directions. The temporal dynamics of the longitudinal spin Seebeck effect exhibits that the effect depends on the diffusion of bulk thermal-magnons in the thermal gradient in the ferromagnetic-insulator|normal-metal system.

  11. X-ray small-angle scattering from sputtered CeO{sub 2}/C bilayers

    SciTech Connect (OSTI)

    Haviar, S.; Dubau, M.; Khalakhan, I.; Vorokhta, M.; Matolinova, I.; Matolin, V.; Vales, V.; Endres, J.; Holy, V.; Buljan, M.; Bernstorff, S.

    2013-01-14

    Surface and interface morphology of cerium oxide/carbon bilayers used as thin-film catalysts is studied by grazing-incidence small-angle x-ray scattering, scanning electron microscopy, and atomic-force microscopy, and the dependence of the structural parameters on the thicknesses of the constituting layers is investigated. The applicability of x-ray scattering and its advantages over standard analytical methods are discussed.

  12. Effect of dipolar moments in domain sizes of lipid bilayers and monolayers

    E-Print Network [OSTI]

    Alex Travesset

    2006-12-14

    Lipid domains are found in systems such as multi-component bilayer membranes and single component monolayers at the air-water interface. It was shown by Andelman et al. (Comptes Rendus 301, 675 (1985)) and McConnell et al. (Phys. Chem. {\\bf 91}, 6417 (1987)) that in monolayers, the size of the domains results from balancing the line tension, which favors the formation of a large single circular domain, against the electrostatic cost of assembling the dipolar moments of the lipids. In this paper, we present an exact analytical expression for the electric potential, ion distribution and electrostatic free energy for different problems consisting of three different slabs with different dielectric constants and Debye lengths, with a circular homogeneous dipolar density in the middle slab. From these solutions, we extend the calculation of domain sizes for monolayers to include the effects of finite ionic strength, dielectric discontinuities (or image charges) and the polarizability of the dipoles and further generalize the calculations to account for domains in lipid bilayers. In monolayers, the size of the domains is dependent on the different dielectric constants but independent of ionic strength. In asymmetric bilayers, where the inner and outer leaflets have different dipolar densities, domains show a strong size dependence with ionic strength, with molecular-sized domains that grow to macroscopic phase separation with increasing ionic strength. We discuss the implications of the results for experiments and briefly consider their relation to other two dimensional systems such as Wigner crystals or heteroepitaxial growth.

  13. Neutron reflectivity study of substrate surface chemistry effects on supported phospholipid bilayer formation on (1120) sapphire.

    SciTech Connect (OSTI)

    Oleson, Timothy A.; Sahai, Nita; Wesolowski, David J; Dura, Joseph A; Majkrzak, Charles F; Giuffre, Anthony J.

    2012-01-01

    Oxide-supported phospholipid bilayers (SPBs) used as biomimetric membranes are significant for a broad range of applications including improvement of biomedical devices and biosensors, and in understanding biomineralization processes and the possible role of mineral surfaces in the evolution of pre-biotic membranes. Continuous-coverage and/or stacjed SPBs retain properties (e.,g. fluidity) more similar to native biological membranes, which is desirable for most applications. Using neutron reflectivity, we examined face coverage and potential stacking of dipalmitoylphosphatidylcholine (DPPC) bilayers on the (1120) face of sapphire (a-Al2O3). Nearly full bilayers were formed at low to neutral pH, when the sapphire surface is positively charged, and at low ionic strength (l=15 mM NaCl). Coverage decreased at higher pH, close to the isoelectric point of sapphire, and also at high I>210mM, or with addition of 2mM Ca2+. The latter two effects are additive, suggesting that Ca2+ mitigates the effect of higher I. These trends agree with previous results for phospholipid adsorption on a-Al2O3 particles determined by adsorption isotherms and on single-crystal (1010) sapphire by atomic force microscopy, suggesting consistency of oxide surface chemistry-dependent effects across experimental techniques.

  14. Dielectric matrix and plasmon dispersion in strongly coupled electronic bilayer liquids

    SciTech Connect (OSTI)

    Golden, Kenneth I.; Mahassen, Hania; Kalman, Gabor J.; Senatore, Gaetano; Rapisarda, F. [Department of Mathematics and Statistics, University of Vermont, Burlington, Vermont 05405 (United States); Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Dipartimento di Fisica Teorica, Universita di Trieste, Strada Costiera 11, 34014 Trieste, Italy and INFM-Democritos National Simulation Center, Trieste (Italy); Dipartimento di Fisica Teorica, Universita di Trieste, Strada Costiera 11, 34014 Trieste (Italy)

    2005-03-01

    We develop a dielectric matrix and analyze plasmon dispersion in strongly coupled charged-particle bilayers in the T=0 quantum domain. The formulation is based on the classical quasilocalized charge approximation (QLCA) and extends the QLCA formalism into the quantum domain. Its development, which parallels that of the two-dimensional companion paper [Phys. Rev. E 70, 026406 (2004)] by three of the authors, generalizes the single-layer scalar formalism therein to a bilayer matrix formalism. Using pair correlation function data generated from diffusion Monte Carlo simulations, we calculate the dispersion of the in-phase and out-of-phase plasmon modes over a wide range of high-r{sub s} values and layer separations. The out-of-phase spectrum exhibits an exchange-correlation induced long-wavelength energy gap in contrast to earlier predictions of acoustic dispersion softened by exchange and correlations. The energy gap is similar to what has been previously predicted for classical charged-particle bilayers and subsequently confirmed by recent molecular dynamics computer simulations.

  15. Phase diagram of the CF{sub 4} monolayer and bilayer on graphite

    SciTech Connect (OSTI)

    Thomas, Petros; Hess, George B.

    2014-05-21

    We report an experimental study of physisorbed monolayers and bilayers of CF{sub 4} on graphite using infrared reflection absorption spectroscopy supplemented by ellipsometry. The symmetric C–F stretch mode ?{sub 3} near 1283 cm{sup ?1} in the gas is strongly blue shifted in the film by dynamic dipole coupling. This blue shift provides a very sensitive measure of the inter-molecular spacing in the monolayer and, less directly, in the bilayer. We find that important corrections are necessary to the volumetric coverage scales used in previous heat capacity and x-ray diffraction studies of this system. This requires quantitative and some qualitative changes to the previously proposed phase diagram. We find evidence for a new phase transition in the middle of the hexagonal incommensurate region and construct new phase diagrams in both the variables coverage-temperature and chemical potential-temperature. We determine the compressibility and thermal expansion in the low-pressure hexagonal incommensurate phase and values for the entropy change in several phase transitions. Below about 55 K there is evidence of solution of up to 7% of an impurity, most likely CO, in our monolayer but not the bilayer film.

  16. Enhanced Casimir effect for doped graphene

    E-Print Network [OSTI]

    M. Bordag; I. Fialkovsky; D. Vassilevich

    2015-07-30

    We analyze the Casimir interaction of doped graphene. To this end we derive a simple expression for the finite temperature polarization tensor with a chemical potential. It is found that doping leads to a strong enhancement of the Casimir force reaching almost $60\\%$ in quite realistic situations. This result should be important for planning and interpreting the Casimir measurements, especially taking into account that the Casimir interaction of undoped graphene is rather weak.

  17. Preparation of nitrogen-doped carbon tubes

    DOE Patents [OSTI]

    Chung, Hoon Taek; Zelenay, Piotr

    2015-12-22

    A method for synthesizing nitrogen-doped carbon tubes involves preparing a solution of cyanamide and a suitable transition metal-containing salt in a solvent, evaporating the solvent to form a solid, and pyrolyzing the solid under an inert atmosphere under conditions suitable for the production of nitrogen-doped carbon tubes from the solid. Pyrolyzing for a shorter period of time followed by rapid cooling resulted in a tubes with a narrower average diameter.

  18. Enhanced Casimir effect for doped graphene

    E-Print Network [OSTI]

    Bordag, M; Vassilevich, D

    2015-01-01

    We analyze the Casimir interaction of doped graphene. To this end we derive a simple expression for the finite temperature polarization tensor with a chemical potential. It is found that doping leads to a strong enhancement of the Casimir force reaching almost $60\\%$ in quite realistic situations. This result should be important for planning and interpreting the Casimir measurements, especially taking into account that the Casimir interaction of undoped graphene is rather weak.

  19. Preparation and electrical transport properties of quasi free standing bilayer graphene on SiC (0001) substrate by H intercalation

    SciTech Connect (OSTI)

    Yu, Cui; Liu, Qingbin; Li, Jia; Lu, Weili; He, Zezhao; Cai, Shujun; Feng, Zhihong

    2014-11-03

    We investigate the temperature dependent electrical transport properties of quasi-free standing bilayer graphene on 4H-SiC (0001) substrate. Three groups of monolayer epitaxial graphene and corresponding quasi-free standing bilayer graphene with different crystal quality and layer number homogeneity are prepared. Raman spectroscopy and atomic-force microscopy are used to obtain their morphologies and layer number, and verify the complete translation of buffer layer into graphene. The highest room temperature mobility reaches 3700?cm{sup 2}/V·s for the quasi-free standing graphene. The scattering mechanism analysis shows that poor crystal quality and layer number inhomogeneity introduce stronger interacting of SiC substrate to the graphene layer and more impurities, which limit the carrier mobility of the quasi-free standing bilayer graphene samples.

  20. A new class of high ZT doped bulk nanothermoelectrics through...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    new class of high ZT doped bulk nanothermoelectrics through bottom-up synthesis A new class of high ZT doped bulk nanothermoelectrics through bottom-up synthesis Reports on...

  1. Modelling of noble anaesthetic gases and high hydrostatic pressure effects in lipid bilayers

    SciTech Connect (OSTI)

    Moskovitz, Yevgeny [Middle Tennessee State Univ., Murfreesboro, TN (United States). Dept. of Chemistry; Univ. of Capetown (South Africa). Dept. of Chemistry, Scientific Computing Research Unit; Yang, Hui [Middle Tennessee State Univ., Murfreesboro, TN (United States). Dept. of Chemistry

    2015-01-01

    Our objective was to study molecular processes that might be responsible for inert gas narcosis and high-pressure nervous syndrome. The classical molecular dynamics trajectories (200 ns-long) of dioleoylphosphatidylcholine (DOPC) bilayers simulated by the Berger force field were evaluated for water and the atomic distribution of noble gases around DOPC molecules at a pressure range of 1 - 1000 bar and temperature of 310 Kelvin. Xenon and argon have been tested as model gases for general anesthetics, and neon has been investigated for distortions that are potentially responsible for neurological tremor at hyperbaric conditions. The analysis of stacked radial pair distribution functions of DOPC headgroup atoms revealed the explicit solvation potential of gas molecules, which correlates with their dimensions. The orientational dynamics of water molecules at the biomolecular interface should be considered as an influential factor; while excessive solvation effects appearing in the lumen of membrane-embedded ion channels could be a possible cause of inert gas narcosis. All the noble gases tested exhibit similar patterns of the order parameter for both DOPC acyl chains, which is opposite to the patterns found for the order parameter curve at high hydrostatic pressures in intact bilayers. This finding supports the ‘critical volume’ hypothesis of anesthesia pressure reversal. The irregular lipid headgroup-water boundary observed in DOPC bilayers saturated with neon in the pressure range of 1 - 100 bar could be associated with the possible manifestation of neurological tremor at the atomic scale. The non-immobilizer neon also demonstrated the highest momentum impact on the normal component of the DOPC diffusion coefficient representing monolayers undulations rate, which indicates enhanced diffusivity, rather than atom size, as the key factor.

  2. Modelling of noble anaesthetic gases and high hydrostatic pressure effects in lipid bilayers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moskovitz, Yevgeny; Yang, Hui

    2015-01-08

    Our objective was to study molecular processes that might be responsible for inert gas narcosis and high-pressure nervous syndrome. The classical molecular dynamics trajectories (200 ns-long) of dioleoylphosphatidylcholine (DOPC) bilayers simulated by the Berger force field were evaluated for water and the atomic distribution of noble gases around DOPC molecules at a pressure range of 1 - 1000 bar and temperature of 310 Kelvin. Xenon and argon have been tested as model gases for general anesthetics, and neon has been investigated for distortions that are potentially responsible for neurological tremor at hyperbaric conditions. The analysis of stacked radial pair distributionmore »functions of DOPC headgroup atoms revealed the explicit solvation potential of gas molecules, which correlates with their dimensions. The orientational dynamics of water molecules at the biomolecular interface should be considered as an influential factor; while excessive solvation effects appearing in the lumen of membrane-embedded ion channels could be a possible cause of inert gas narcosis. All the noble gases tested exhibit similar patterns of the order parameter for both DOPC acyl chains, which is opposite to the patterns found for the order parameter curve at high hydrostatic pressures in intact bilayers. This finding supports the ‘critical volume’ hypothesis of anesthesia pressure reversal. The irregular lipid headgroup-water boundary observed in DOPC bilayers saturated with neon in the pressure range of 1 - 100 bar could be associated with the possible manifestation of neurological tremor at the atomic scale. The non-immobilizer neon also demonstrated the highest momentum impact on the normal component of the DOPC diffusion coefficient representing monolayers undulations rate, which indicates enhanced diffusivity, rather than atom size, as the key factor.« less

  3. High transition temperature superconductor/insulator bilayers for the development of ultra-fast electronics

    SciTech Connect (OSTI)

    Sirena, M.; Félix, L. Avilés; Instituto Balseiro, Universidad Nacional de Cuyo and CNEA, 8400 Bariloche ; Haberkorn, N.

    2013-07-29

    High transition temperature superconductor (HTc)/SrTiO{sub 3} (STO) bilayers were fabricated by sputtering deposition on (100) STO substrates. Their transport and morphological properties were characterized using conductive atomic force microscopy. The STO barriers present good insulating properties, with long attenuation lengths (? ? 1 nm) which reduce the junction resistance and increase the operating critical current. The samples present roughness values smaller than 1 nm, with an extremely low density of surface defects (?5 × 10{sup ?5} defects/?m{sup 2}). The high control of the barrier quality over large defect free surfaces is encouraging for the development of microelectronics devices based in HTc Josephson junctions.

  4. Confined bilayer water melts like two highly correlated layers of Lennard-Jones particles

    E-Print Network [OSTI]

    Jon Zubeltzu; Fabiano Corsetti; M. -V. Férnandez-Serra; Emilio Artacho

    2015-10-20

    A confined bilayer of water is studied at different temperatures and densities by classical and {\\em ab initio} molecular dynamics simulations. At high density, hydrogen disorder is found to be behind the reported continuous phase transition. We observe the existence of a hexatic phase, suggesting that the Kosterlitz-Thouless-Halperin-Nelson-Young theory of a defect-mediated 2D crystal melting occurs. The liquid at different densities maintains the basic structure of the triangular ice. The two layers of liquid at high density show a strong correlation between one another without exchange of matter.

  5. Monte-Carlo study of the phase transition in the AA-stacked bilayer graphene

    E-Print Network [OSTI]

    A. A. Nikolaev; M. V. Ulybyshev

    2014-12-04

    Tight-binding model of the AA-stacked bilayer graphene with screened electron-electron interactions has been studied using the Hybrid Monte Carlo simulations on the original double-layer hexagonal lattice. Instantaneous screened Coulomb potential is taken into account using Hubbard-Stratonovich transformation. G-type antiferromagnetic ordering has been studied and the phase transition with spontaneous generation of the mass gap has been observed. Dependence of the antiferromagnetic condensate on the on-site electron-electron interaction is examined.

  6. Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition

    E-Print Network [OSTI]

    Fern ández-Pacheco, A.; Ummelen, F. C.; Mansell, R.; Petit, D.; Lee, J. H.; Swagten, H. J. M.; Cowburn, R. P.

    2014-09-05

    , Phys. Rev. Lett. 98, 117204, (2007). 19P. J. Metaxas, R. L. Stamps, J.-P. Jamet, J. Ferr#2;e, V. Baltz, B. Rodmacq, and P. Politi, Phys. Rev. Lett. 104, 237206 (2010). 20N. Wiese, T. Dimopoulos, M. R€uhrig, J. Wecker, and G. Reiss, J. Appl. Phys. 98... Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition A. Fernández-Pacheco, F. C. Ummelen, R. Mansell, D. Petit, J. H. Lee, H. J. M. Swagten, and R. P. Cowburn Citation: Applied Physics...

  7. LDRD final report on engineered superconductivity in electron-hole bilayers.

    SciTech Connect (OSTI)

    Lyo, Sungkwun Kenneth; Dunn, Roberto G.; Lilly, Michael Patrick; Tibbetts-Russell, D. R.; Stephenson, Larry L.; Seamons, John Andrew; Reno, John Louis; Bielejec, Edward Salvador; Baca, Wes Edmund; Simmons, Jerry Alvon

    2005-01-01

    Macroscopic quantum states such as superconductors, Bose-Einstein condensates and superfluids are some of the most unusual states in nature. In this project, we proposed to design a semiconductor system with a 2D layer of electrons separated from a 2D layer of holes by a narrow (but high) barrier. Under certain conditions, the electrons would pair with the nearby holes and form excitons. At low temperature, these excitons could condense to a macroscopic quantum state either through a Bose-Einstein condensation (for weak exciton interactions) or a BCS transition to a superconductor (for strong exciton interactions). While the theoretical predictions have been around since the 1960's, experimental realization of electron-hole bilayer systems has been extremely difficult due to technical challenges. We identified four characteristics that if successfully incorporated into a device would give the best chances for excitonic condensation to be observed. These characteristics are closely spaced layers, low disorder, low density, and independent contacts to allow transport measurements. We demonstrated each of these characteristics separately, and then incorporated all of them into a single electron-hole bilayer device. The key to the sample design is using undoped GaAs/AlGaAs heterostructures processed in a field-effect transistor geometry. In such samples, the density of single 2D layers of electrons could be varied from an extremely low value of 2 x 10{sup 9} cm{sup -2} to high values of 3 x 10{sup 11} cm{sup -2}. The extreme low values of density that we achieved in single layer 2D electrons allowed us to make important contributions to the problem of the metal insulator transition in two dimensions, while at the same time provided a critical base for understanding low density 2D systems to be used in the electron-hole bilayer experiments. In this report, we describe the processing advances to fabricate single and double layer undoped samples, the low density results on single layers, and evidence for gateable undoped bilayers.

  8. Metal-doped organic gels and method thereof

    DOE Patents [OSTI]

    Satcher, Jr., Joe H. (Patterson, CA); Baumann, Theodore F. (Tracy, CA)

    2007-10-23

    Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

  9. Metal-doped organic gels and method thereof

    DOE Patents [OSTI]

    Satcher, Jr., Joe H.; Baumann, Theodore F.

    2003-09-02

    Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

  10. Doped luminescent materials and particle discrimination using same

    DOE Patents [OSTI]

    Doty, F. Patrick; Allendorf, Mark D; Feng, Patrick L

    2014-10-07

    Doped luminescent materials are provided for converting excited triplet states to radiative hybrid states. The doped materials may be used to conduct pulse shape discrimination (PSD) using luminescence generated by harvested excited triplet states. The doped materials may also be used to detect particles using spectral shape discrimination (SSD).

  11. Doping against the native propensity of MoS?: Degenerate hole doping by cation substitution

    SciTech Connect (OSTI)

    Suh, Joonki; Park, Tae-Eon; Lin, Der-Yuh; Fu, Deyi; Park, Joonsuk; Jung, Hee Joon; Chen, Yabin; Ko, Changhyun; Jang, Chaun; Sun, Yinghui; Sinclair, Robert; Chang, Joonyeon; Tongay, Sefaattin; Wu, Junqiao

    2014-12-10

    Layered transition metal dichalcogenides (TMDs) draw much attention as the key semiconducting material for two-dimensional electrical, optoelectronic, and spintronic devices. For most of these applications, both n- and p-type materials are needed to form junctions and support bipolar carrier conduction. However, typically only one type of doping is stable for a particular TMD. For example, molybdenum disulfide (MoS?) is natively an n-type presumably due to omnipresent electron-donating sulfur vacancies, and stable/controllable p-type doping has not been achieved. The lack of p-type doping hampers the development of charge-splitting p–n junctions of MoS?, as well as limits carrier conduction to spin-degenerate conduction bands instead of the more interesting, spin-polarized valence bands. Traditionally, extrinsic p-type doping in TMDs has been approached with surface adsorption or intercalation of electron-accepting molecules. However, practically stable doping requires substitution of host atoms with dopants where the doping is secured by covalent bonding. In this work, we demonstrate stable p-type conduction in MoS? by substitutional niobium (Nb) doping, leading to a degenerate hole density of ~3 × 10¹? cm?³. Structural and X-ray techniques reveal that the Nb atoms are indeed substitutionally incorporated into MoS? by replacing the Mo cations in the host lattice. van der Waals p–n homojunctions based on vertically stacked MoS? layers are fabricated, which enable gate-tunable current rectification. A wide range of microelectronic, optoelectronic, and spintronic devices can be envisioned from the demonstrated substitutional bipolar doping of MoS?. From the miscibility of dopants with the host, it is also expected that the synthesis technique demonstrated here can be generally extended to other TMDs for doping against their native unipolar propensity.

  12. Spectroscopic investigation of nitrogen doped graphene

    SciTech Connect (OSTI)

    Podila, R.; Spear, J. T. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Chacon-Torres, J.; Pichler, T.; Ayala, P. [Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna (Austria); Rao, A. M. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Center for Optical Materials Science and Technology, Clemson University, Clemson, South Carolina 29634 (United States)

    2012-09-17

    Current research efforts are aimed at controlling the electronic properties via doping graphene. Previously, dopant-induced changes in the Fermi velocity were observed to result in an effectively downshifted Raman peak below the G Prime -band for n-doped carbon nanotubes. However, in the case of N-doped graphene, we find that several Raman features vary depending upon both dopant concentration and its bonding environment. For instance, only pyridinic/pyrrolic dopants were observed to result in intense D/D Prime -bands with a concomitant downshift in the G Prime -band. Here, we correlate x-ray photoelectron measurements with Raman spectra to elucidate effects of dopant bonding configuration on vibrational properties of graphene.

  13. Lanthanide and actinide doped glasses as reference standards for dye doped systems

    SciTech Connect (OSTI)

    Pope, E.J.A.; Hentschel, A.

    1996-12-31

    Organic dye molecules are well known to be subject to chemical and optical bleaching damage, temperature instability, and other forms of optical degradation. Currently recognized methods of referencing rely upon fluorescent salt solutions, such as quinine sulfate. In this paper, optically-active lanthanide and actinide doped gel-glasses are compared as reference standards for dye doped polymers. Samples are subjected to continuous illumination by 254 nm UV radiation. While dye-doped polymers exhibited approximately 65 percent decline in fluorescence intensity after 96 hours of irradiation, glass samples and glass powder in resin showed no decline in fluorescence intensities.

  14. Relaxation back to equilibrium after cessation of shear for confined colloidal bilayers

    E-Print Network [OSTI]

    René Messina; Hartmut Löwen

    2005-06-24

    Crystalline bilayers of charged colloidal suspensions which are confined between two parallel plates and sheared via a relative motion of the two plates are studied by extensive Brownian dynamics computer simulations. The charge-stabilized suspension is modeled by a Yukawa pair potential. The unsheared equilibrium configuration are two crystalline layers with a nested quadratic in-plane structure. For increasing shear rates $\\dot \\gamma$, we find the following steady states: first, there is a static solid which is elastically sheared until a yield-stress limit is reached. Then there are two crystalline layers sliding on top of each other with a registration procedure. Higher shear rates melt the crystalline bilayers and even higher shear rates lead to a reentrant solid stratified in the shear direction. This qualitative scenario is similar to that found in previous bulk simulations. We have then studied the relaxation of the sheared steady state back to equilibrium after an instantaneous cessation of shear and found a nonmonotonic behavior of the typical relaxation time as a function of the shear rate $\\dot \\gamma$. In particular, application of high shear rates accelerates the relaxation back to equilibrium since shear-ordering facilitates the growth of the equilibrium crystal. This mechanism can be used to grow defect-free colloidal crystals from strongly sheared suspensions. Our theoretical predictions can be verified in real-space experiments of strongly confined charged suspensions.

  15. Strain-induced energy band gap opening in two-dimensional bilayered silicon film

    E-Print Network [OSTI]

    Ji, Zhonghang; Voon, Lok C Lew Yan; Zhuang, Yan

    2015-01-01

    This work presents a theoretical study of the structural and electronic properties of bilayered silicon films under in-plane biaxial strain/stress using density functional theory. Atomic structures of the two-dimensional silicon films are optimized by using both the local-density approximation and generalized gradient approximation. In the absence of strain/stress, five buckled hexagonal honeycomb structures of the bilayered silicon film have been obtained as local energy minima and their structural stability has been verified. These structures present a Dirac-cone shaped energy band diagram with zero energy band gaps. Applying tensile biaxial strain leads to a reduction of the buckling height. Atomically flat structures with zero bucking height have been observed when the AA-stacking structures are under a critical biaxial strain. Increase of the strain between 10.7% ~ 15.4% results in a band-gap opening with a maximum energy band gap opening of ~168.0 meV obtained when 14.3% strain is applied. Energy band d...

  16. Alamethicin in lipid bilayers: Combined use of X-ray scattering and MD simulations Jianjun Pan a

    E-Print Network [OSTI]

    Nagle, John F.

    Alamethicin in lipid bilayers: Combined use of X-ray scattering and MD simulations Jianjun Pan of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA d Canadian Neutron Beam Centre:1PC with varying amounts of alamethicin (Alm). We combine the use of X-ray diffuse scattering

  17. Free energy of the edge of an open lipid bilayer based on the interactions of its constituent molecules

    E-Print Network [OSTI]

    Meisam Asgari; Aisa Biria

    2015-04-05

    Lipid-bilayers are the fundamental constituents of the walls of most living cells and lipid vesicles, giving them shape and compartment. The formation and growing of pores in a lipid bilayer have attracted considerable attention from an energetic point of view in recent years. Such pores permit targeted delivery of drugs and genes to the cell, and regulate the concentration of various molecules within the cell. The formation of such pores is caused by various reasons such as changes in cell environment, mechanical stress or thermal fluctuations. Understanding the energy and elastic behaviour of a lipid-bilayer edge is crucial for controlling the formation and growth of such pores. In the present work, the interactions in the molecular level are used to obtain the free energy of the edge of an open lipid bilayer. The resulted free-energy density includes terms associated with flexural and torsional energies of the edge, in addition to a line-tension contribution. The line tension, elastic moduli, and spontaneous normal and geodesic curvatures of the edge are obtained as functions of molecular distribution, molecular dimensions, cutoff distance, and the interaction strength. These parameters are further analyzed by implementing a soft-core interaction potential in the microphysical model. The dependence of the elastic free-energy of the edge to the size of the pore is reinvestigated through an illustrative example, and the results are found to be in agreement with the previous observations.

  18. A Metal-Organic Bilayer Open Framework with a Dynamic Component: Single-Crystal-to-Single-Crystal Transformations

    E-Print Network [OSTI]

    Paik Suh, Myunghyun

    ,5 catalysis,6,7 and sensor technology.8,9 Compared with the formation of inorganic porous materials devices. Here we report the synthesis of a bilayer open framework, which retains its framework are useful in design and synthesis of multidimensional networks since they have two fixed vacant coordination

  19. Membrane fusion is the process whereby two separate lipid bilayers merge to become one. It is essential for

    E-Print Network [OSTI]

    McMahon, Harvey

    Membrane fusion is the process whereby two separate lipid bilayers merge to become one). The best-studied process involving membrane fusion is exocytosis, whereby vesicles fuse with the limiting membrane. However, large numbers of membrane-fusion events occur between intracellular compartments

  20. 788 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 12, NO. 6, DECEMBER 2003 Deformation of Blanketed and Patterned Bilayer

    E-Print Network [OSTI]

    Zhang, Katherine Yanhang

    microelectromechanical systems (MEMS) applications. They may serve passive and/or active structural roles. The former788 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 12, NO. 6, DECEMBER 2003 Deformation of high-yield, dimensionally stable MEMS devices utilizing bilayer material systems. Although our

  1. Dye-sensitized solar cells based on a nanoparticle/nanotube bilayer structure and their equivalent circuit analysis

    E-Print Network [OSTI]

    Lin, Zhiqun

    of anatase and rutile phases. As one of the major renewable energy sources, solar energy has the potential to become an essential component of future global energy production. Dye sensitized solar cells (DSSCs)1Dye-sensitized solar cells based on a nanoparticle/nanotube bilayer structure and their equivalent

  2. PHYSICAL REVIEW E VOLUME 51, NUMBER 1 JANUARY 1995 Phase transitions and modulated phases in lipid bilayers

    E-Print Network [OSTI]

    MacKintosh, F.C.

    -water as a function of temperature and relative humidity, showing the I,Lpl, and Ppt phases. The Ppt phase occurs-assemble into bilayer mem- branes in which their oily tails are shielded &om contact with the surrounding water. Under there are three, also exhibit hexatic bond-angle order and are dis- tinguished &om each other by the angle

  3. Importance of Doping and Frustration in Itinerant Fe-doped Cr2Al

    SciTech Connect (OSTI)

    Susner, Michael A; Parker, David S; Safa-Sefat, Athena

    2015-01-01

    We have performed an experimental and theoretical study comparing the effects of Fe-doping of Cr2Al, an antiferromagnet with a N el temperature of 670 K, with known results on Fe-doping of antiferromagnetic bcc Cr. (Cr1-xFex)2Al materials are found to exhibit a rapid suppression of antiferromagnetic order with the presence of Fe, decreasing TN to 170 K for x=0.10. Antiferromagnetic behavior disappears entirely at x 0.125 after which point increasing paramagnetic behavior is exhibited. This is unlike the effects of Fe doping of bcc antiferromagnetic Cr, in which TN gradually decreases followed by the appearance of a ferromagnetic state. Theoretical calculations explain that the Cr2Al-Fe suppression of magnetic order originates from two effects: the first is band narrowing caused by doping of additional electrons from Fe substitution that weakens itinerant magnetism; the second is magnetic frustration of the Cr itinerant moments in Fe-substituted Cr2Al. In pure-phase Cr2Al, the Cr moments have an antiparallel alignment; however, these are destroyed through Fe substitution and the preference of Fe for parallel alignment with Cr. This is unlike bulk Fe-doped Cr alloys in which the Fe anti-aligns with the Cr atoms, and speaks to the importance of the Al atoms in the magnetic structure of Cr2Al and Fe-doped Cr2Al.

  4. An Investigation of Spin and Charge Transport in Doped and Defected Graphene

    E-Print Network [OSTI]

    McCreary, Kathleen M.

    2012-01-01

    hydrogenated epitaxial graphene. Appl. Phys. Lett. 98,of magnetoconductance in graphene devices. Phys. Rev. B 83,carrier mobilities in graphene and its bilayer. Phys. Rev.

  5. Nitrogen-doped zirconia: A comparison with cation stabilized zirconia

    SciTech Connect (OSTI)

    Lee, Jong-Sook . E-mail: jong-sook.lee@fkf.mpg.de; Lerch, Martin; Maier, Joachim

    2006-01-15

    The conductivity behavior of nitrogen-doped zirconia is compared with that of zirconia doped with lower-valent cations and discussed in the framework of defect-defect interactions. While nominally introducing the same number of vacancies as yttrium, nitrogen dopants introduced in the anion sublattice of zirconia lead to substantially different defect kinetics and energetics. Compared to the equivalent yttrium doping nitrogen doping in the Y-Zr-O-N system substantially increases the activation energy and correspondingly decreases the conductivity at temperatures below 500{sup -}bar C in the vacancy range below 4mol%. The comparison of N-doped zirconia and zirconia systems doped with size-matched cation stabilizers, such as Sc, Yb and Y, shows that elastically driven vacancy-vacancy ordering interactions can phenomenologically account for the temperature- and composition-dependence. It is striking that materials with superior high-temperature conductivities due to weak dopant-vacancy interactions undergo severe deterioration at low temperature due to the strong vacancy-ordering. The analysis also explains qualitatively similar effects of Y co-doping in Yb-, Sc-, and N-doped zirconia. Small amount of Y in N-doped zirconia as well as in Sc-doped zirconia appears to hinder the formation of the long-range ordered phase and thus enhance the conductivity substantially.

  6. Hydrodynamic Collective Effects of Active Protein Machines in Solution and Lipid Bilayers

    E-Print Network [OSTI]

    Alexander Mikhailov; Raymond Kapral

    2015-03-09

    The cytoplasm and biomembranes in biological cells contain large numbers of proteins that cyclically change their shapes. They are molecular machines that can function as molecular motors or carry out many other tasks in the cell. We analyze the effects that hydrodynamic flows induced by active proteins have on other passive molecules in solution or membranes. We show that the diffusion constants of passive particles are enhanced substantially. Furthermore, when gradients of active proteins are present, a chemotaxis-like drift of passive particles takes place. In lipid bilayers, the effects are strongly nonlocal, so that active inclusions in the membrane contribute to diffusion enhancement and the drift. The results indicate that the transport properties of passive particles in systems containing active proteins machines operating under nonequilibrium conditions differ from their counterparts in systems at thermal equilibrium.

  7. Full control of magnetism in a manganite bilayer by ferroelectric polarization

    SciTech Connect (OSTI)

    Dong, Shuai [Southeast University, Nanjing, China] [Southeast University, Nanjing, China; Dagotto, Elbio R [ORNL] [ORNL

    2013-01-01

    An oxide heterostructure made of manganite bilayers and ferroelectric perovskites is predicted to lead to the full control of magnetism when switching the ferroelectric polarizations. By using asymmetric polar interfaces in the superlattices, more electrons occupy the Mn layer at the n-type interface side than at the p-type side. This charge disproportionation can be enhanced or suppressed by the ferroelectric polarization. Quantum model and density functional theory calculations reach the same conclusion: a ferromagnetic-ferrimagnetic phase transition with maximal change >90% of the total magnetization can be achieved by switching the polarization s direction. This function is robust and provides full control of the magnetization s magnitude, not only its direction, via electrical methods.

  8. Indirect-direct band gap transition through electric tuning in bilayer MoS{sub 2}

    SciTech Connect (OSTI)

    Zhang, Z. Y.; Si, M. S., E-mail: sims@lzu.edu.cn; Wang, Y. H.; Gao, X. P. [Key laboratory for Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou 730 000 (China)] [Key laboratory for Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou 730 000 (China); Sung, Dongchul; Hong, Suklyun [Graphene Research Institute, Sejong University, Seoul 143 747 (Korea, Republic of)] [Graphene Research Institute, Sejong University, Seoul 143 747 (Korea, Republic of); He, Junjie [Department of Physics, Xiangtan University, Hunan 411 105 (China)] [Department of Physics, Xiangtan University, Hunan 411 105 (China)

    2014-05-07

    We investigate the electronic properties of bilayer MoS{sub 2} exposed to an external electric field by using first-principles calculations. It is found that a larger interlayer distance, referring to that by standard density functional theory (DFT) with respect to that by DFT with empirical dispersion corrections, makes indirect-direct band gap transition possible by electric control. We show that external electric field effectively manipulates the valence band contrast between the K- and ?-valleys by forming built-in electric dipole fields, which realizes an indirect-direct transition before a semiconductor-metal transition happens. Our results provide a novel efficient access to tune the electronic properties of two-dimensional layered materials.

  9. Lipid Bilayer-Coated Curcumin-based Mesoporous Organosilica Nanoparticles for Cellular Delivery

    E-Print Network [OSTI]

    Stefan Datz; Hanna Engelke; Constantin v. Schirnding; Linh Nguyen; Thomas Bein

    2015-09-08

    Effective and controlled drug delivery systems with on-demand release abilities and biocompatible properties receive enormous attention for biomedical applications. Here, we describe a novel inorganic-organic hybrid material with a strikingly high organic content of almost 50 wt%. The colloidal periodic mesoporous organosilica (PMO) nanoparticles synthesized in this work consist entirely of curcumin and ethane derivatives serving as constituents that are crosslinked by siloxane bridges, without any added silica. These mesoporous curcumin nanoparticles (MCNs) exhibit very high surface areas (over 1000 m2/g), narrow particle size distribution (around 200 nm) and a strikingly high stability in simulated biological media. Additionally, the MCNs are used as a cargo delivery system in live-cell experiments. A supported lipid bilayer (SLB) efficiently seals the pores and releases Rhodamin B as model cargo in HeLa cells. This novel nanocarrier concept provides a promising platform for the development of controllable and highly biocompatible theranostic systems.

  10. Optimal electrode geometries for 2-dimensional ion arrays with bi-layer ion traps

    E-Print Network [OSTI]

    F. N. Krauth; J. Alonso; J. P. Home

    2014-11-04

    We investigate electrode geometries required to produce periodic 2-dimensional ion-trap arrays with the ions placed between two planes of electrodes. We present a generalization of previous methods for traps containing a single electrode plane to this new geometry, and show that for a given ion-electrode distance and applied voltages, the inter-ion distance can be reduced by a factor of up to 3 relative to single-plane traps. This represents an increase by a factor of 9 in the trap density and a factor of 27 in the exchange coupling between the oscillatory motion of neighboring ions. The resulting traps are also considerably deeper for bi-layer structures than for single-plane traps. These results could offer a useful path towards 2-dimensional ion arrays for quantum simulation. We also discuss issues with the fabrication of such traps.

  11. Lipid Bilayer-Coated Curcumin-based Mesoporous Organosilica Nanoparticles for Cellular Delivery

    E-Print Network [OSTI]

    Datz, Stefan; Schirnding, Constantin v; Nguyen, Linh; Bein, Thomas

    2015-01-01

    Effective and controlled drug delivery systems with on-demand release abilities and biocompatible properties receive enormous attention for biomedical applications. Here, we describe a novel inorganic-organic hybrid material with a strikingly high organic content of almost 50 wt%. The colloidal periodic mesoporous organosilica (PMO) nanoparticles synthesized in this work consist entirely of curcumin and ethane derivatives serving as constituents that are crosslinked by siloxane bridges, without any added silica. These mesoporous curcumin nanoparticles (MCNs) exhibit very high surface areas (over 1000 m2/g), narrow particle size distribution (around 200 nm) and a strikingly high stability in simulated biological media. Additionally, the MCNs are used as a cargo delivery system in live-cell experiments. A supported lipid bilayer (SLB) efficiently seals the pores and releases Rhodamin B as model cargo in HeLa cells. This novel nanocarrier concept provides a promising platform for the development of controllable ...

  12. Defining the Free-Energy Landscape of Curvature-Inducing Proteins on Membrane Bilayers

    E-Print Network [OSTI]

    Tourdot, Richard W; Radhakrishnan, Ravi

    2015-01-01

    Curvature-sensing and curvature-remodeling proteins are known to reshape cell membranes, and this remodeling event is essential for key biophysical processes such as tubulation, exocytosis, and endocytosis. Curvature-inducing proteins can act as curvature sensors as well as induce curvature in cell membranes to stabilize emergent high curvature, non-spherical, structures such as tubules, discs, and caveolae. A definitive understanding of the interplay between protein recruitment and migration, the evolution of membrane curvature, and membrane morphological transitions is emerging but remains incomplete. Here, within a continuum framework and using the machinery of Monte Carlo simulations, we introduce and compare three free-energy methods to delineate the free-energy landscape of curvature-inducing proteins on bilayer membranes. We demonstrate the utility of the Widom test-particle/field insertion methodology in computing the excess chemical potentials associated with curvature-inducing proteins on the membra...

  13. Thermodynamic Free Energy Methods to Investigate Shape Transitions In Bilayer Membranes

    E-Print Network [OSTI]

    Ramakrishnan, N; Radhakrishnan, Ravi

    2015-01-01

    The conformational free energy landscape of a system is a fundamental thermodynamic quantity of importance particularly in the study of soft matter and biological systems, in which the entropic contributions play a dominant role. While computational methods to delineate the free energy landscape are routinely used to analyze the relative stability of conformational states, to determine phase boundaries, and to compute ligand-receptor binding energies its use in problems involving the cell membrane is limited. Here, we present an overview of four different free energy methods to study morphological transitions in bilayer membranes, induced either by the action of curvature remodeling proteins or due to the application of external forces. Using a triangulated surface as a model for the cell membrane and using the framework of dynamical triangulation Monte Carlo, we have focused on the methods of Widom insertion, thermodynamic integration, Bennett acceptance scheme, and umbrella sampling and weighted histogram a...

  14. Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition

    SciTech Connect (OSTI)

    Fernández-Pacheco, A., E-mail: af457@cam.ac.uk; Mansell, R.; Petit, D.; Lee, J. H.; Cowburn, R. P. [Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ummelen, F. C.; Swagten, H. J. M. [Department of Applied Physics, Center for NanoMaterials, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-09-01

    We have designed a bilayer synthetic antiferromagnet where the order of layer reversal can be selected by varying the sweep rate of the applied magnetic field. The system is formed by two ultra-thin ferromagnetic layers with different proximities to the spin reorientation transition, coupled antiferromagnetically using Ruderman-Kittel-Kasuya-Yosida interactions. The different dynamic magnetic reversal behavior of both layers produces a crossover in their switching fields for field rates in the kOe/s range. This effect is due to the different effective anisotropy of both layers, added to an appropriate asymmetric antiferromagnetic coupling between them. Field-rate controlled selective switching of perpendicular magnetic anisotropy layers as shown here can be exploited in sensing and memory applications.

  15. Strong Interaction Effects at a Fermi Surface in a Model for Voltage-Biased Bilayer Graphene

    E-Print Network [OSTI]

    Armour, Wes; Strouthos, Costas

    2015-01-01

    Monte Carlo simulation of a 2+1 dimensional model of voltage-biased bilayer graphene, consisting of relativistic fermions with chemical potential mu coupled to charged excitations with opposite sign on each layer, has exposed non-canonical scaling of bulk observables near a quantum critical point found at strong coupling. We present a calculation of the quasiparticle dispersion relation E(k) as a function of exciton source j in the same system, employing partially twisted boundary conditions to boost the number of available momentum modes. The Fermi momentum k_F and superfluid gap Delta are extracted in the limit j tends to zero for three different values of mu, and support a strongly interacting scenario at the Fermi surface with Delta of order O(mu). We propose an explanation for the observation mu < k_F in terms of a dynamical critical exponent z < 1.

  16. Strong Interaction Effects at a Fermi Surface in a Model for Voltage-Biased Bilayer Graphene

    E-Print Network [OSTI]

    Wes Armour; Simon Hands; Costas Strouthos

    2015-09-11

    Monte Carlo simulation of a 2+1 dimensional model of voltage-biased bilayer graphene, consisting of relativistic fermions with chemical potential mu coupled to charged excitations with opposite sign on each layer, has exposed non-canonical scaling of bulk observables near a quantum critical point found at strong coupling. We present a calculation of the quasiparticle dispersion relation E(k) as a function of exciton source j in the same system, employing partially twisted boundary conditions to boost the number of available momentum modes. The Fermi momentum k_F and superfluid gap Delta are extracted in the limit j tends to zero for three different values of mu, and support a strongly interacting scenario at the Fermi surface with Delta of order O(mu). We propose an explanation for the observation mu < k_F in terms of a dynamical critical exponent z < 1.

  17. Highly Emissive Transition Metal Ion Doped Semiconducting Nanocrystals

    SciTech Connect (OSTI)

    Jana, Santanu; Srivastava, Bhupendra B.; Pradhan, Narayan; Sarma, D. D.

    2011-07-15

    Doped semiconductor nanocrystals (d-dots), specifically ones not containing heavy metal ions, have the potential to become a class of mainstream emissive materials. Mn- and Cu-doped ZnSe or ZnS d-dots can cover an emission window similar to that of the current workhorse of intrinsic quantum dot (q-dots) emitters, CdSe nanocrystals. We synthesized high quality stable Cu doped ZnSe in nonpolar as well as polar solvent. The emission intensity of these doped nanocrystals is found stable for months under UV irradiation, after different multifunctional ligand which is important for any biological detection. We have also synthesized the stable Mn doped ZnS in nonpolar solvent more than 50% QY.. The doped nanocrystals are characterized by TEM, XRD, EPR and ICP analysis.

  18. Transparent and conductive indium doped cadmium oxide thin films prepared by pulsed filtered cathodic arc deposition

    E-Print Network [OSTI]

    Zhu, Yuankun

    2014-01-01

    7. Optical bandgap of the doped CdO thin films as a functionelectrical properties of In-doped CdO thin films fabricatedand transparent Ti-doped CdO films by pulsed laser

  19. Substrate and method for the formation of continuous magnesium diboride and doped magnesium diboride wire

    DOE Patents [OSTI]

    Suplinskas, Raymond J. (Haverhill, MA); Finnemore, Douglas (Ames, IA); Bud'ko, Serquei (Ames, IA); Canfield, Paul (Ames, IA)

    2007-11-13

    A chemically doped boron coating is applied by chemical vapor deposition to a silicon carbide fiber and the coated fiber then is exposed to magnesium vapor to convert the doped boron to doped magnesium diboride and a resultant superconductor.

  20. Does fluoride disrupt hydrogen bond network in cationic lipid bilayer? Time-dependent fluorescence shift of Laurdan and molecular dynamics simulations

    SciTech Connect (OSTI)

    Pokorna, Sarka; Jurkiewicz, Piotr; Hof, Martin; Vazdar, Mario; Cwiklik, Lukasz; Jungwirth, Pavel

    2014-12-14

    Time-dependent fluorescence shift (TDFS) of Laurdan embedded in phospholipid bilayers reports on hydration and mobility of the phospholipid acylgroups. Exchange of H{sub 2}O with D{sub 2}O prolongs the lifetime of lipid-water and lipid-water-lipid interactions, which is reflected in a significantly slower TDFS kinetics. Combining TDFS measurements in H{sub 2}O and D{sub 2}O hydrated bilayers with atomistic molecular dynamics (MD) simulations provides a unique tool for characterization of the hydrogen bonding at the acylgroup level of lipid bilayers. In this work, we use this approach to study the influence of fluoride anions on the properties of cationic bilayers composed of trimethylammonium-propane (DOTAP). The results obtained for DOTAP are confronted with those for neutral phosphatidylcholine (DOPC) bilayers. Both in DOTAP and DOPC H{sub 2}O/D{sub 2}O exchange prolongs hydrogen-bonding lifetime and does not disturb bilayer structure. These results are confirmed by MD simulations. TDFS experiments show, however, that for DOTAP this effect is cancelled in the presence of fluoride ions. We interpret these results as evidence that strongly hydrated fluoride is able to steal water molecules that bridge lipid carbonyls. Consequently, when attracted to DOTAP bilayer, fluoride disrupts the local hydrogen-bonding network, and the differences in TDFS kinetics between H{sub 2}O and D{sub 2}O hydrated bilayers are no longer observed. A distinct behavior of fluoride is also evidenced by MD simulations, which show different lipid-ion binding for Cl{sup ?} and F{sup ?}.

  1. Tungsten-doped thin film materials

    DOE Patents [OSTI]

    Xiang, Xiao-Dong; Chang, Hauyee; Gao, Chen; Takeuchi, Ichiro; Schultz, Peter G.

    2003-12-09

    A dielectric thin film material for high frequency use, including use as a capacitor, and having a low dielectric loss factor is provided, the film comprising a composition of tungsten-doped barium strontium titanate of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3, where X is between about 0.5 and about 1.0. Also provided is a method for making a dielectric thin film of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3 and doped with W, where X is between about 0.5 and about 1.0, a substrate is provided, TiO.sub.2, the W dopant, Ba, and optionally Sr are deposited on the substrate, and the substrate containing TiO.sub.2, the W dopant, Ba, and optionally Sr is heated to form a low loss dielectric thin film.

  2. Photoinduced phenomena in chalcogenide glasses doped with metals

    E-Print Network [OSTI]

    Boolchand, Punit

    on relaxation of photodarkening in a-As2Se3 doped with Sn and rare-earth (RE) ions (Dy, Pr, Hon, Sm3 Nd, Er3 for chalcogenide glasses doped with rare-earth ions as perspective materials for fibre optics amplifiers operating and the kinetics ofphotodarkening in amonhous As2Se3:Sn thin films at %) and and AsSe3 doped with rare-earth ions

  3. Aluminum-doped Zinc Oxide Nanoink

    Energy Innovation Portal (Marketing Summaries) [EERE]

    2014-08-15

    Scientists at Berkeley Lab have developed a method for fabricating conductive aluminum-doped zinc oxide (AZO) nanocrystals that provide a lower cost, less toxic, earth-abundant alternative to the widely used transparent conductive oxide (TCO) indium tin oxide while offering comparable optical and electronic properties. TCOs are used in devices such as flat screen displays, photovoltaic cells, photochromic windows, chemical sensors, and biosensors....

  4. Strongly enhanced oxygen ion transport through samarium-doped...

    Office of Scientific and Technical Information (OSTI)

    Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films Citation Details In-Document Search This content will become publicly...

  5. Strain Doping: A New Approach to Understanding and Controlling...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Materials Synthesis from Atoms to Systems Strain Doping: A New Approach to Understanding and Controlling Advanced Materials June 16, 2015 Inserting helium atoms (one is symbolized...

  6. Doping of ZnO nanowires using phosphorus diffusion from a spin-on doped glass source

    SciTech Connect (OSTI)

    Bocheux, A.; Robin, I. C.; Bonaimé, J.; Hyot, B.; Feuillet, G.; Kolobov, A. V.; Fons, P.; Mitrofanov, K. V.; Tominaga, J.; Tamenori, Y.

    2014-05-21

    In this article, we report on ZnO nanowires that were phosphorus doped using a spin on dopant glass deposition and diffusion method. Photoluminescence measurements suggest that this process yields p-doped ZnO. The spatial location of P atoms was studied using x-ray near-edge absorption structure spectroscopy and it is concluded that the doping is amphoteric with P atoms located on both Zn and O sites.

  7. Low-voltage and hysteresis-free organic thin-film transistors employing solution-processed hybrid bilayer gate dielectrics

    SciTech Connect (OSTI)

    Ha, Tae-Jun [Department of Electronic Materials Engineering, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

    2014-07-28

    This study presents a promising approach to realize low-voltage (<3?V) organic thin-film transistors (OTFTs) exhibiting improved electrical and optical stability. Such device performance results from the use of solution-processed hybrid bilayer gate dielectrics consisting of zirconium dioxide (high-k dielectric) and amorphous fluoropolymer, CYTOP{sup ®} (low-k dielectric). Employing a very thin amorphous fluoropolymer film reduces interfacial defect-states by repelling water molecules and other aqueous chemicals from an organic semiconductor active layer due to the hydrophobic surface-property. The chemically clean interface, stemming from decrease in density of trap states improves all the key device properties such as field-effect mobility, threshold voltage, and sub-threshold swing. Furthermore, degradation by electrical bias-stress and photo-induced hysteresis were suppressed in OTFTs employing hybrid bilayer gate dielectrics.

  8. Arrangement of Annexin A2 tetramer and its impact on the structure and diffusivity of supported lipid bilayers

    E-Print Network [OSTI]

    Kirstin Fritz; Georg Fritz; Barbara Windschiegl; Claudia Steinem; Bert Nickel

    2010-09-16

    Annexins are a family of proteins that bind to anionic phospholipid membranes in a Ca2+-dependent manner. Annexin A2 forms heterotetramers (Anx A2t) with the S100A10 (p11) protein dimer. The tetramer is capable of bridging phospholipid membranes and it has been suggested to play a role in Ca2+-dependent exocytosis and cell-cell adhesion of metastatic cells. Here, we employ x-ray reflectivity measurements to resolve the conformation of Anx A2t upon Ca2+-dependent binding to single supported lipid bilayers (SLBs) composed of different mixtures of anionic (POPS) and neutral (POPC) phospholipids. Based on our results we propose that Anx A2t binds in a side-by-side configuration, i.e., both Anx A2 monomers bind to the bilayer with the p11 dimer positioned on top. Furthermore, we observe a strong decrease of lipid mobility upon binding of Anx A2t to SLBs with varying POPS content. X-ray reflectivity measurements indicate that binding of Anx A2t also increases the density of the SLB. Interestingly, in the protein-facing leaflet of the SLB the lipid density is higher than in the substrate-facing leaflet. This asymmetric densification of the lipid bilayer by Anx A2t and Ca2+ might have important implications for the biochemical mechanism of Anx A2t-induced endo- and exocytosis.

  9. Study of structure of the TiO{sub 2}–MoO{sub 3} bilayer films by Raman spectroscopy

    SciTech Connect (OSTI)

    Santos, Elias de Barros; Sigoli, Fernando Aparecido; Mazali, Italo Odone

    2014-12-15

    Highlights: • TiO{sub 2}–MoO{sub 3} bilayer thin films were easily prepared by dip-coating technique. • Ti and Mo metallo-organic compounds were used as source of its respective oxide. • TiO{sub 2} in anatase phase and orthorhombic phase of ?-MoO{sub 3} were identified. • The bilayer structure was investigated by Raman spectroscopy. - Abstract: In this work, TiO{sub 2}–MoO{sub 3} films were easily prepared by dip-coating technique and metallo-organic decomposition process (MOD). Raman analyses indicate the formation of TiO{sub 2} in anatase phase and orthorhombic phase of ?-MoO{sub 3}. It was observed that the Raman bands intensities attributed to TiO{sub 2} and MoO{sub 3} oxides were dependent on the number of decomposition–deposition cycles (DDC). The different number of DDC generates films with different thicknesses and the Raman signal was sensitive to this variation. Raman analyses provided qualitative information about the bilayer structure of the bi-component TiO{sub 2}–MoO{sub 3} films, which was confirmed by scanning electron microscopy. In this direction, the dip-coating technique and MOD process can be an efficient strategy to facile preparation of many samples to be used in applications.

  10. Impurity Doping Effect in High T c Superconductors

    E-Print Network [OSTI]

    Impurity Doping Effect in High T c Superconductors Yong­Jihn Kim and K. J. Chang Department observed that impurity doping and/or ion­beam­induced dam­ age in high T c superconductors cause a metal­ calization effect on superconductivity, we examine the variation of T c with increasing of impurity

  11. Superlattice doped layers for amorphous silicon photovoltaic cells

    DOE Patents [OSTI]

    Arya, Rajeewa R. (Doylestown, PA)

    1988-01-12

    Superlattice doped layers for amorphous silicon photovoltaic cells comprise a plurality of first and second lattices of amorphous silicon alternatingly formed on one another. Each of the first lattices has a first optical bandgap and each of the second lattices has a second optical bandgap different from the first optical bandgap. A method of fabricating the superlattice doped layers also is disclosed.

  12. Controllable N-Doping of Graphene Beidou Guo,,

    E-Print Network [OSTI]

    Gong, Jian Ru

    Controllable N-Doping of Graphene Beidou Guo,, Qian Liu, Erdan Chen, Hewei Zhu, Liang Fang in graphene are central to many electronic applications of graphene. Here we report N-doped graphene obtained by NH3 annealing after N+ -ion irradiation of graphene samples. First, the evolution of the graphene

  13. Femtosecond Laser Ablation of Silicon: Nanoparticles, Doping and Photovoltaics

    E-Print Network [OSTI]

    Mazur, Eric

    Femtosecond Laser Ablation of Silicon: Nanoparticles, Doping and Photovoltaics A thesis presented Laser Ablation of Silicon: Nanoparticles, Doping and Photovoltaics Eric Mazur Brian R. Tull Abstract irradiated surface layer to the grain boundaries. #12;iv Lastly, we measure the photovoltaic properties

  14. Schematic structure of nitrogen-doped graphene showing carbon

    E-Print Network [OSTI]

    Gong, Jian Ru

    method for graphene doping, and is compatible with current complementary metal oxide semiconductor (CMOSSchematic structure of nitrogen- doped graphene showing carbon (gray) and nitrogen (blue) NPG Asia Materials research highlight | doi:10.1038/asiamat.2010.204 Published online 13 December 2010 Graphene

  15. Effects of Quantum Confinement on the Doping Limit of Semiconductor

    E-Print Network [OSTI]

    Wu, Junqiao

    . The magnitude of this effect in a given material is found to be determined by two material properties of semiconductor nanostructures in terms of their fundamental material parameters. Doping limits in various bulk are generated in semiconductor materials in response to extrinsic doping so as to pull EF back toward EFS

  16. Polarization controllable Fresnel lens using dye-doped liquid crystals

    E-Print Network [OSTI]

    Wu, Shin-Tson

    Polarization controllable Fresnel lens using dye- doped liquid crystals Tsung-Hsien Lin,1,2 Yuhua controllable Fresnel zone plate lens is demonstrated using a photo-induced alignment of the dye-doped liquid. X. Ren, S. Liu, and X. Zhang, "Fabrication of off-axis holographic Fresnel lens used as multiplexer

  17. Toward IFE Oriented Laser Chains: Cryogenically Cooled Ytterbium Doped Materials

    SciTech Connect (OSTI)

    Bourdet, G. [LULI, Unite Mixte no 7605 CNRS-CEA-Ecole Polytechnique-Universite Pierre et Marie Curie, Route de Saclay, 91128 Palaiseau (France); Casagrande, O. [Departement des Lasers de Puissance, Centre d'Etudes Scientifiques et Techniques d'Aquitaine (CESTA), Commissariat a l'Energie Atomique BP2, 33114 Le Barp (France); Thales Laser SA, Domaine de Corbeville, Route Departementale 128, BP 46-91401 Orsay Cedex (France); Cardinali, V.; Deguil-Robin, N.; Le Garrec, B. [Departement des Lasers de Puissance, Centre d'Etudes Scientifiques et Techniques d'Aquitaine (CESTA), Commissariat a l'Energie Atomique BP2, 33114 Le Barp (France)

    2009-09-27

    With the aim to set up Inertial Fusion Energy (IFE) driver, we develop the properties of the Ytterbium doped materials and the problems met when designing such a system: essentially thermal management and ASE gain depletion. We after present the experimental results obtained using sesquioxide Yb{sup 3+} doped ceramics at cryogenic temperature. We also propose a solution for minimizing the ASE problem.

  18. Nitrogen-Doped Graphene and its Application in Electrochemical Biosensing

    SciTech Connect (OSTI)

    Wang, Ying; Shao, Yuyan; Matson, Dean W.; Li, Jinghong; Lin, Yuehe

    2010-05-05

    Chemical doping with foreign atoms is an effective method to intrinsically modify the properties of host materials. Among them, nitrogen (N) doping plays a critical role in regulating the electronic properties of carbon materials. Recently, graphene as a true 2-dimensional carbon material has shown fascinating applications in bioelectronics and biosensors. In this paper, we report a facile strategy to prepare N-doped graphene by using plasma treatment of pristine graphene synthesized via chemical method. Meanwhile, a possible schematic diagram has been proposed to detail the structure of N-doped graphene. By controlling the exposure time, N percentage in host grapheme can be regulated ranging from 0.11% to 1.35%. Moreover, the as prepared N-doped graphene has displayed high electrocatalytic activity to hydrogen peroxide and further been used for glucose biosensing with concentration as low as 0.01 mM in the presence of interferences.

  19. Nitrogen doped zinc oxide thin film

    SciTech Connect (OSTI)

    Li, Sonny X.

    2003-12-15

    To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N{sub 2}O and N{sub 2}. Upon annealing, N{sub 2}O decomposes into N{sub 2} and O{sub 2}. In furnace-annealed samples N{sub 2} redistributes diffusively and forms gaseous N{sub 2} bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N{sup +} implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N{sub 2}){sub O} and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

  20. Scintillation of rare earth doped fluoride nanoparticles

    SciTech Connect (OSTI)

    Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

    2011-09-12

    The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

  1. Effect of stacking sequence on crystallization in Al/a-Ge bilayer thin films

    SciTech Connect (OSTI)

    Zhang, Tianwei; Zhang, Weilin; Ma, Fei, E-mail: mafei@mail.xjtu.edu.cn, E-mail: kwxu@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Huang, Yuhong [College of Physics and Information Technology, Shaanxi Normal University, Xi'an, Shaanxi 710062 (China); Xu, Kewei, E-mail: mafei@mail.xjtu.edu.cn, E-mail: kwxu@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China and Department of Physics and Opt-electronic Engineering, Xi'an University of Arts and Science, Xi'an, Shaanxi 710065 (China)

    2014-05-15

    Two types of bilayer thin films with different deposition sequences, i.e., amorphous Ge under Al (a-Ge/Al) and the inverse (Al/a-Ge), were prepared by magnetron sputtering at room temperature. In-situ and ex-situ thermal annealing were compared to study the effect of the stacking sequence on crystallization of amorphous Ge. Although metal-induced crystallization occurred in both cases at low temperature, layer exchange was observed only in a-Ge/Al. In fact, compressive stress could usually be produced when Ge atoms diffused into Al grain boundaries and crystallized there. In the a-Ge/Al system, the stress could be released through diffusion of Al atoms onto the surface and formation of hillocks. Thus, grain boundary (GB) mediated crystallization was dominant in the whole process and layer exchange occurred. However, in the Al/a-Ge system, it was difficult for stress to be relaxed because the Ge sublayer and substrate restricted the diffusion of Al atoms. GB-mediated crystallization was, therefore, considerably suppressed and interface-mediated crystallization was preferred without layer exchange. This leads to distinct morphologies of dendrites in the two systems.

  2. Quantum radiations from exciton condensate in Electron-Hole Bilayer Systems

    E-Print Network [OSTI]

    Jinwu Ye; T. Shi; Longhua Jiang; C. P. Sun

    2009-07-10

    Superfluid has been realized in Helium-4, Helium-3 and ultra-cold atoms. It has been widely used in making high-precision devices and also in cooling various systems. There have been extensive experimental search for possible exciton superfluid (ESF) in semiconductor electron-hole bilayer (EHBL) systems below liquid Helium temperature. However, exciton superfluid are meta-stable and will eventually decay through emitting photons. Here we study quantum nature of photons emitted from the excitonic superfluid (ESF) phase in the semiconductor EHBL and find that the light emitted from the excitonic superfluid has unique and unusual features not shared by any other atomic or condensed matter systems. We show that the emitted photons along the direction perpendicular to the layer are in a coherent state, those along all tilted directions are in a two modes squeezed state. We determine the two mode squeezing spectra, the angle resolved power spectrum, the line shapes of both the momentum distribution curve (MDC) and the energy distribution curve (EDC). From the two photon correlation functions, we find there are photon bunching, the photo-count statistics is super-Poissonian. We discuss how several important parameters such as the chemical potential, the exciton decay rate, the quasiparticle energy spectrum and the dipole-dipole interaction strength between the excitons in our theory can be extracted from the experimental data and comment on available experimental data on both EDC and MDC.

  3. Neutron scattering from myelin revisited: bilayer asymmetry and water-exchange kinetics

    SciTech Connect (OSTI)

    Denninger, Andrew R. [Boston College, Chestnut Hill, MA 02467 (United States); Demé, Bruno; Cristiglio, Viviana [Institut Laue–Langevin (ILL), CS 20156, F-38042 Grenoble CEDEX 9 (France); LeDuc, Géraldine [European Synchrotron Radiation Facility (ESRF), CS 40220, F-38043 Grenoble CEDEX 9 (France); Feller, W. Bruce [NOVA Scientific Inc., Sturbridge, MA 01566 (United States); Kirschner, Daniel A., E-mail: kirschnd@bc.edu [Boston College, Chestnut Hill, MA 02467 (United States)

    2014-12-01

    The structure of internodal myelin in the rodent central and peripheral nervous systems has been determined using neutron diffraction. The kinetics of water exchange in these tissues is also described. Rapid nerve conduction in the central and peripheral nervous systems (CNS and PNS, respectively) of higher vertebrates is brought about by the ensheathment of axons with myelin, a lipid-rich, multilamellar assembly of membranes. The ability of myelin to electrically insulate depends on the regular stacking of these plasma membranes and on the presence of a number of specialized membrane-protein assemblies in the sheath, including the radial component, Schmidt–Lanterman incisures and the axo–glial junctions of the paranodal loops. The disruption of this fine-structure is the basis for many demyelinating neuropathies in the CNS and PNS. Understanding the processes that govern myelin biogenesis, maintenance and destabilization requires knowledge of myelin structure; however, the tight packing of internodal myelin and the complexity of its junctional specializations make myelin a challenging target for comprehensive structural analysis. This paper describes an examination of myelin from the CNS and PNS using neutron diffraction. This investigation revealed the dimensions of the bilayers and aqueous spaces of myelin, asymmetry between the cytoplasmic and extracellular leaflets of the membrane, and the distribution of water and exchangeable hydrogen in internodal multilamellar myelin. It also uncovered differences between CNS and PNS myelin in their water-exchange kinetics.

  4. Asymmetric Electron Transport at Monolayer-Bilayer Heterojunctions of Epitaxial Graphene

    SciTech Connect (OSTI)

    Li, An-Ping [ORNL] [ORNL; Clark, Kendal W [ORNL] [ORNL; Zhang, Xiaoguang [ORNL] [ORNL; Gu, Gong [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); He, Guowei [Carnegie Mellon University (CMU)] [Carnegie Mellon University (CMU); Feenstra, Randall [Carnegie Mellon University (CMU)] [Carnegie Mellon University (CMU)

    2014-01-01

    The symmetry of the graphene honeycomb lattice is a key element determining many of graphene s unique electronic properties, such as the linear energy-momentum dispersion and the suppressed backscattering 1,2. However, line defects in large-scale epitaxial graphene films, such as grain boundaries, edges, surface steps, and changes in layer thickness, often break the sublatttice symmetry and can impact transport properties of graphene profoundly 3-6. Here we report asymmetric electron transport upon polarity reversal at individual monolayer-bilayer (ML-BL) boundaries in epitaxial graphene on SiC (0001), revealed by scanning tunneling potentiometry. A greater voltage drop is observed when the current flows from BL to ML graphene than in the reverse direction, and the difference remains nearly unchanged with increasing current. This is not a typical nonlinear conductance due to electron transmission through an asymmetric potential. Rather, it indicates the opening of a dynamic energy gap at the Fermi energy due to the Coulomb interaction between the injected nonequilibrium electron density and the pseudospin polarized Friedel oscillation charge density at the boundary. This intriguing heterojunction transport behavior opens a new avenue towards novel quantum functions such as quantum switching.

  5. Strong exciton-photon coupling with colloidal quantum dots in a high-Q bilayer microcavity

    SciTech Connect (OSTI)

    Giebink, Noel C; Wiederrecht, Gary P.; Wasielewski, Michael R

    2011-01-01

    We demonstrate evanescently coupled bilayer microcavities with Q -factors exceeding 250 fabricated by a simple spin-coating process. The cavity architecture consists of a slab waveguide lying upon a low refractive index spacer layer supported by a glass substrate. For a lossless guide layer, the cavity Q depends only on the thickness of the low index spacer and in principle can reach arbitrarily high values. We demonstrate the versatility of this approach by constructing cavities with a guide layer incorporating CdSe/ZnS core/shell quantum dots, where we observe strong coupling and hybridization between the 1S(e)-1S{sub 3/2} (h) and 1S(e)-2S{sub 3/2} (h) exciton states mediated by the cavity photon. This technique greatly simplifies the fabrication of high-Q planar microcavities for organic and inorganic quantum dot thin films and opens up new opportunities for the study of nonlinear optical phenomena in these materials.

  6. Transverse dielectric matrix and shear mode dispersion in strongly coupled electronic bilayer liquids

    SciTech Connect (OSTI)

    Golden, Kenneth I; Mahassen, Hania; Senatore, Gaetano; Rapisarda, Francesco [Department of Mathematics and Statistics, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05401-1455 (United States); Dipartimento di Fisica Teorica, Universita di Trieste, Strada Costiera 11, 34014 Trieste, Italy and INFM-CNR-Democritos National Simulation Center, Trieste (Italy); Dipartimento di Fisica Teorica, Universita di Trieste, Strada Costiera 11, 34014, Trieste (Italy)

    2006-11-15

    The authors develop a transverse dielectric matrix and from it they calculate the shear mode dispersion in strongly coupled charged-particle bilayer liquids in the T=0 quantum domain. The formulation is based on the classical quasilocalized charge approximation (QLCA) and extends the QLCA formalism into the quantum domain. Its development parallels and complements the development of a similarly extended longitudinal dielectric matrix formalism reported in a recent companion work [K. I. Golden, H. Mahassen, G. J. Kalman, G. Senatore, and F. Rapisarda, Phys. Rev. E 71, 036401 (2005)]. Using pair correlation function data generated from diffusion Monte Carlo simulations, the authors calculate the dispersion of the in-phase and out-of-phase shear modes over a wide range of high-r{sub s} values and layer separations. Over the coupling range 10{<=}r{sub s}{<=}30 and for layer separations 0.2/{radical}({pi}n){<=}d{<=}0.5/{radical}({pi}n), the present study predicts the existence of a robust out-of-phase gapped shear mode dispersion in the domain of the q,{omega}-plane above the left boundary of the RPA single-pair excitation region; under these conditions, the out-of-phase collective excitation is entirely immune to Landau damping and can be safely considered to be mostly unaffected by diffusive-migrational damping.

  7. Sandwich beam model for free vibration analysis of bilayer graphene nanoribbons with interlayer shear effect

    SciTech Connect (OSTI)

    Nazemnezhad, Reza E-mail: rnazemnezhad@du.ac.ir; Shokrollahi, Hassan; Hosseini-Hashemi, Shahrokh

    2014-05-07

    In this study, sandwich beam model (SM) is proposed for free vibration analysis of bilayer graphene nanoribbons (BLGNRs) with interlayer shear effect. This model also takes into account the intralayer (in-plane) stretch of graphene nanoribbons. The molecular dynamics (MD) simulations using the software LAMMPS and Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential are done to validate the accuracy of the sandwich model results. The MD simulation results include the two first frequencies of cantilever BLGNRs with different lengths and two interlayer shear moduli, i.e., 0.25 and 4.6?GPa. These two interlayer shear moduli, 0.25 and 4.6?GPa, can be obtained by sliding a small flake of graphene on a large graphene substrate when the parameter of E-LJ term in AIREBO potential, epsilon-CC, is set to be 2.84 and 45.44?meV, respectively. The SM results for a wide range of bending rigidity values show that the proposed model, i.e., the SM, predicts much better than the previous beam model in which the intralayer stretch is ignored. In addition, it is observed that the model can properly predict the natural frequencies of BLGNRs for various values of the bending rigidity and the interlayer shear modulus.

  8. LASER TRANSFER DOPING USING AMORPHOUS SILICON Rafel Ferr (Correspondence author)1

    E-Print Network [OSTI]

    LASER TRANSFER DOPING USING AMORPHOUS SILICON Rafel Ferré (Correspondence author)1 , Ralf Gogolin1@isfh.de ABSTRACT: We demonstrate and characterize "Laser Transfer Doping" (LTD) for producing locally doped regions. For this purpose we use nanosecond pulsed laser for transferring phosphorus doped amorphous silicon from a carrier

  9. Structural Detuning of Pump Absorption Rate in Doped Fiber for the Enhancement of Power Conversion Efficiency

    E-Print Network [OSTI]

    Park, Namkyoo

    Structural Detuning of Pump Absorption Rate in Doped Fiber for the Enhancement of Power Conversion Doped Fiber Amplifier. With proper adjustments on doping profiles for the reduction of pump absorption rate, it becomes possible to optimize pump evolution map inside the doped fiber to get better power

  10. Color stable manganese-doped phosphors

    DOE Patents [OSTI]

    Lyons, Robert Joseph (Burnt Hills, NY); Setlur, Anant Achyut (Niskayuna, NY); Deshpande, Anirudha Rajendra (Twinsburg, OH); Grigorov, Ljudmil Slavchev (Sofia, BG)

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  11. Quantum electrodynamics with anisotropic scaling: Heisenberg-Euler action and Schwinger pair production in the bilayer graphene

    E-Print Network [OSTI]

    M. I. Katsnelson; G. E. Volovik

    2012-03-19

    We discuss quantum electrodynamics emerging in the vacua with anisotropic scaling. Systems with anisotropic scaling were suggested by Horava in relation to the quantum theory of gravity. In such vacua the space and time are not equivalent, and moreover they obey different scaling laws, called the anisotropic scaling. Such anisotropic scaling takes place for fermions in bilayer graphene, where if one neglects the trigonal warping effects the massless Dirac fermions have quadratic dispersion. This results in the anisotropic quantum electrodynamics, in which electric and magnetic fields obey different scaling laws. Here we discuss the Heisenberg-Euler action and Schwinger pair production in such anisotropic QED

  12. Self-doped molecular composite battery electrolytes

    DOE Patents [OSTI]

    Harrup, Mason K.; Wertsching, Alan K.; Stewart, Frederick F.

    2003-04-08

    This invention is in solid polymer-based electrolytes for battery applications. It uses molecular composite technology, coupled with unique preparation techniques to render a self-doped, stabilized electrolyte material suitable for inclusion in both primary and secondary batteries. In particular, a salt is incorporated in a nano-composite material formed by the in situ catalyzed condensation of a ceramic precursor in the presence of a solvated polymer material, utilizing a condensation agent comprised of at least one cation amenable to SPE applications. As such, the counterion in the condensation agent used in the formation of the molecular composite is already present as the electrolyte matrix develops. This procedure effectively decouples the cation loading levels required for maximum ionic conductivity from electrolyte physical properties associated with condensation agent loading levels by utilizing the inverse relationship discovered between condensation agent loading and the time domain of the aging step.

  13. Direct band gap narrowing in highly doped Ge

    E-Print Network [OSTI]

    Han, Zhaohong

    Direct band gap narrowing in highly doped n-type Ge is observed through photoluminescence measurements by determining the spectrum peak shift. A linear relationship between the direct band gap emission and carrier concentration ...

  14. Self-doping effects in epitaxially grown graphene

    E-Print Network [OSTI]

    Siegel, David A.

    2009-01-01

    The electronic properties of graphene, Rev. Mod. Phys. (inE?ects in Epitaxially-Grown Graphene D.A. Siegel, 1, 2 S.Y.2009) Abstract Self-doping in graphene has been studied by

  15. Spin filtering in a ?-doped magnetic-electric-barrier nanostructure

    SciTech Connect (OSTI)

    Li, Shuai; Lu, Mao-Wang Jiang, Ya-Qing; Chen, Sai-Yan

    2014-09-15

    We report a theoretical study on spin-polarized transport in a ?-doped magnetic-electric-barrier nanostructure, which can be realized in experiments by depositing two ferromagnetic stripes on top and bottom of a semiconductor heterostructure under an applied voltage and by using atomic layer doping technique. The spin-polarized behavior of the electron in this device is found to be quite sensitive to the ?-doping. One can conveniently tune the degree of the electron spin polarization by adjusting the weight and/or position of the ?-doping. Thus, the involved nansosystem can be employed as a controllable spin filter, which may be helpful for exploiting new spin-polarized source for spintronics applications.

  16. Fluorine compounds for doping conductive oxide thin films

    DOE Patents [OSTI]

    Gessert, Tim; Li, Xiaonan; Barnes, Teresa M; Torres, Jr., Robert; Wyse, Carrie L

    2013-04-23

    Methods of forming a conductive fluorine-doped metal oxide layer on a substrate by chemical vapor deposition are described. The methods may include heating the substrate in a processing chamber, and introducing a metal-containing precursor and a fluorine-containing precursor to the processing chamber. The methods may also include adding an oxygen-containing precursor to the processing chamber. The precursors are reacted to deposit the fluorine-doped metal oxide layer on the substrate. Methods may also include forming the conductive fluorine-doped metal oxide layer by plasma-assisted chemical vapor deposition. These methods may include providing the substrate in a processing chamber, and introducing a metal-containing precursor, and a fluorine-containing precursor to the processing chamber. A plasma may be formed that includes species from the metal-containing precursor and the fluorine-containing precursor. The species may react to deposit the fluorine-doped metal oxide layer on the substrate.

  17. Potential Antiferromagnetic Fluctuations in Hole-Doped Iron-Pnictide...

    Office of Scientific and Technical Information (OSTI)

    Fluctuations in Hole-Doped Iron-Pnictide Superconductor Ba1-xKxFe2As2 Studied by 75As Nuclear Magnetic Resonance Measurement0.1143JPSJ.81.054704 Citation Details In-Document...

  18. Performance and mix measurements of indirect drive Cu doped Be...

    Office of Scientific and Technical Information (OSTI)

    indirect drive Cu doped Be implosions Authors: Casey, D T ; Woods, T ; Smalyuk, V A ; Hurricane, O A ; Glebov, V Y ; Stoeckl, C ; Theobald, W ; Wallace, R ; Nikroo, A ; Shuldberg,...

  19. Doped carbon nanostructure field emitter arrays for infrared imaging

    DOE Patents [OSTI]

    Korsah, Kofi (Knoxville, TN) [Knoxville, TN; Baylor, Larry R (Farragut, TN) [Farragut, TN; Caughman, John B (Oak Ridge, TN) [Oak Ridge, TN; Kisner, Roger A (Knoxville, TN) [Knoxville, TN; Rack, Philip D (Knoxville, TN) [Knoxville, TN; Ivanov, Ilia N (Knoxville, TN) [Knoxville, TN

    2009-10-27

    An infrared imaging device and method for making infrared detector(s) having at least one anode, at least one cathode with a substrate electrically connected to a plurality of doped carbon nanostructures; and bias circuitry for applying an electric field between the anode and the cathode such that when infrared photons are adsorbed by the nanostructures the emitted field current is modulated. The detectors can be doped with cesium to lower the work function.

  20. Step-edge-induced resistance anisotropy in quasi-free-standing bilayer chemical vapor deposition graphene on SiC

    SciTech Connect (OSTI)

    Ciuk, Tymoteusz [Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Cakmakyapan, Semih; Ozbay, Ekmel [Department of Electrical and Electronics Engineering, Department of Physics, Nanotechnology Research Center, Bilkent University, 06800 Bilkent, Ankara (Turkey); Caban, Piotr; Grodecki, Kacper; Pasternak, Iwona; Strupinski, Wlodek, E-mail: wlodek.strupinski@itme.edu.pl [Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Krajewska, Aleksandra [Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Institute of Optoelectronics, Military University of Technology, Gen. S. Kaliskiego 2, 00-908 Warsaw (Poland); Szmidt, Jan [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland)

    2014-09-28

    The transport properties of quasi-free-standing (QFS) bilayer graphene on SiC depend on a range of scattering mechanisms. Most of them are isotropic in nature. However, the SiC substrate morphology marked by a distinctive pattern of the terraces gives rise to an anisotropy in graphene's sheet resistance, which may be considered an additional scattering mechanism. At a technological level, the growth-preceding in situ etching of the SiC surface promotes step bunching which results in macro steps ~10 nm in height. In this report, we study the qualitative and quantitative effects of SiC steps edges on the resistance of epitaxial graphene grown by chemical vapor deposition. We experimentally determine the value of step edge resistivity in hydrogen-intercalated QFS-bilayer graphene to be ~190 ??m for step height hS = 10 nm and provide proof that it cannot originate from mechanical deformation of graphene but is likely to arise from lowered carrier concentration in the step area. Our results are confronted with the previously reported values of the step edge resistivity in monolayer graphene over SiC atomic steps. In our analysis, we focus on large-scale, statistical properties to foster the scalable technology of industrial graphene for electronics and sensor applications.

  1. Arrangement of Annexin A2 tetramer and its impact on the structure and diffusivity of supported lipid bilayers

    E-Print Network [OSTI]

    Fritz, Kirstin; Windschiegl, Barbara; Steinem, Claudia; Nickel, Bert; 10.1039/c0sm00047g

    2010-01-01

    Annexins are a family of proteins that bind to anionic phospholipid membranes in a Ca2+-dependent manner. Annexin A2 forms heterotetramers (Anx A2t) with the S100A10 (p11) protein dimer. The tetramer is capable of bridging phospholipid membranes and it has been suggested to play a role in Ca2+-dependent exocytosis and cell-cell adhesion of metastatic cells. Here, we employ x-ray reflectivity measurements to resolve the conformation of Anx A2t upon Ca2+-dependent binding to single supported lipid bilayers (SLBs) composed of different mixtures of anionic (POPS) and neutral (POPC) phospholipids. Based on our results we propose that Anx A2t binds in a side-by-side configuration, i.e., both Anx A2 monomers bind to the bilayer with the p11 dimer positioned on top. Furthermore, we observe a strong decrease of lipid mobility upon binding of Anx A2t to SLBs with varying POPS content. X-ray reflectivity measurements indicate that binding of Anx A2t also increases the density of the SLB. Interestingly, in the protein-fa...

  2. Structural, optical, and electrical properties of indium doped cadmium oxide films prepared by pulsed filtered cathodic arc deposition

    E-Print Network [OSTI]

    Zhu, Yuankun

    2014-01-01

    and transparent Ti-doped CdO films by pulsed lasermeasurements on boron-doped CdO thin films. J Mater Sci 46:and optical properties of tin-doped CdO films deposited by

  3. Determining the nonparabolicity factor of the CdO conduction band using indium doping and the Drude theory

    E-Print Network [OSTI]

    Mendelsberg, Rueben

    2014-01-01

    conducting oxides. ga- and in-doped cdo thin films grown bycharacterization of aluminum-doped cdo thin films by sol-geland transparent ti-doped cdo films by pulsed laser

  4. Trench process and structure for backside contact solar cells with polysilicon doped regions

    DOE Patents [OSTI]

    De Ceuster, Denis (Woodside, CA); Cousins, Peter John (Menlo Park, CA); Smith, David D. (Campbell, CA)

    2010-12-14

    A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. An interrupted trench structure separates the P-type doped region from the N-type doped region in some locations but allows the P-type doped region and the N-type doped region to touch in other locations. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. Among other advantages, the resulting solar cell structure allows for increased efficiency while having a relatively low reverse breakdown voltage.

  5. Trench process and structure for backside contact solar cells with polysilicon doped regions

    DOE Patents [OSTI]

    De Ceuster, Denis; Cousins, Peter John; Smith, David D

    2014-03-18

    A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. An interrupted trench structure separates the P-type doped region from the N-type doped region in some locations but allows the P-type doped region and the N-type doped region to touch in other locations. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. Among other advantages, the resulting solar cell structure allows for increased efficiency while having a relatively low reverse breakdown voltage.

  6. Trench process and structure for backside contact solar cells with polysilicon doped regions

    DOE Patents [OSTI]

    De Ceuster, Denis; Cousins, Peter John; Smith, David D

    2013-05-28

    A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. An interrupted trench structure separates the P-type doped region from the N-type doped region in some locations but allows the P-type doped region and the N-type doped region to touch in other locations. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. Among other advantages, the resulting solar cell structure allows for increased efficiency while having a relatively low reverse breakdown voltage.

  7. The effect of substrate temperature and growth rate on the doping efficiency of single crystal boron doped diamond

    SciTech Connect (OSTI)

    Demlow, SN; Rechenberg, R; Grotjohn, T

    2014-10-01

    The substrate growth temperature dependence of the plasma gas-phase to solid-phase doping efficiency in single crystal, boron doped diamond (BDD) deposition is investigated. Single crystal diamond (SCD) is grown by microwave plasma assisted chemical vapor deposition (MPACVD) on high pressure, high temperature (HPHT) type Ib substrates. Samples are grown at substrate temperatures of 850-950 degrees C for each of five doping concentration levels, to determine the effect of the growth temperature on the doping efficiency and defect morphology. The substrate temperature during growth is shown to have a significant effect on the grown sample defect morphology, and a temperature dependence of the doping efficiency is also shown. The effect of the growth rate on the doping efficiency is discussed, and the ratio of the boron concentration in the gas phase to the flux of carbon incorporated into the solid diamond phase is shown to be a more predictive measure of the resulting boron concentration than the gas phase boron to carbon ratio that is more commonly reported. (C) 2014 Elsevier B.V. All rights reserved.

  8. Exploiting lipopolysaccharide-induced deformation of lipid bilayers to modify membrane composition and generate two-dimensional geometric membrane array patterns

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adams, Peter G.; Swingle, Kirstie L.; Paxton, Walter F.; Nogan, John J.; Stromberg, Loreen R.; Firestone, Millicent A.; Mukundan, Harshini; Montaño, Gabriel A.

    2015-05-27

    Supported lipid bilayers have proven effective as model membranes for investigating biophysical processes and in development of sensor and array technologies. The ability to modify lipid bilayers after their formation and in situ could greatly advance membrane technologies, but is difficult via current state-of-the-art technologies. Here we demonstrate a novel method that allows the controlled post-formation processing and modification of complex supported lipid bilayer arrangements, under aqueous conditions. We exploit the destabilization effect of lipopolysaccharide, an amphiphilic biomolecule, interacting with lipid bilayers to generate voids that can be backfilled to introduce desired membrane components. We further demonstrate that when usedmore »in combination with a single, traditional soft lithography process, it is possible to generate hierarchically-organized membrane domains and microscale 2-D array patterns of domains. Significantly, this technique can be used to repeatedly modify membranes allowing iterative control over membrane composition. This approach expands our toolkit for functional membrane design, with potential applications for enhanced materials templating, biosensing and investigating lipid-membrane processes.« less

  9. In-situ high resolution transmission electron microscopy observation of silicon nanocrystal nucleation in a SiO{sub 2} bilayered matrix

    SciTech Connect (OSTI)

    Yang, T. C.-J. Wu, L.; Lin, Z.; Jia, X.; Puthen-Veettil, B.; Zhang, T.; Conibeer, G.; Perez-Wurfl, I.; Kauffmann, Y.; Rothschild, A.

    2014-08-04

    Solid-state nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix was observed at temperatures as low as 450?°C. This was achieved by aberration corrected high-resolution transmission electron microscopy (HRTEM) with real-time in-situ heating up to 600?°C. This technique is a valuable characterization tool especially with the recent interest in Si nanostructures for light emitting devices, non-volatile memories, and third-generation photovoltaics which all typically require a heating step in their fabrication. The control of size, shape, and distribution of the Si nanocrystals are critical for these applications. This experimental study involves in-situ observation of the nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix fabricated through radio frequency co-sputtering. The results show that the shapes of Si nanocrystals in amorphous SiO{sub 2} bilayered matrices are irregular and not spherical, in contrast to many claims in the literature. Furthermore, the Si nanocrystals are well confined within their layers by the amorphous SiO{sub 2}. This study demonstrates the potential of in-situ HRTEM as a tool to observe the real time nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix. Furthermore, ideas for improvements on this in-situ heating HRTEM technique are discussed.

  10. 3>2>1: Investigation of Single Particle Particle and Many Body Physics in Dual-Gated 1,2,3 Layers of Graphene

    E-Print Network [OSTI]

    Velasco, Jairo

    2012-01-01

    data do not fit a thermal activation model, but instead canmeV obtained from thermal activation measurements, but notindeed induced by thermal activation, we then expect that,

  11. 3>2>1: Investigation of Single Particle Particle and Many Body Physics in Dual-Gated 1,2,3 Layers of Graphene

    E-Print Network [OSTI]

    Velasco, Jairo

    2012-01-01

    Quantum Hall effect in graphene pnp junctions Introduction:quality substrate supported graphene pnp junctions 1-7 with2 O 3 that rests on top of graphene supporting the metallic

  12. 3>2>1: Investigation of Single Particle Particle and Many Body Physics in Dual-Gated 1,2,3 Layers of Graphene

    E-Print Network [OSTI]

    Velasco, Jairo

    2012-01-01

    density, graphene behaves similar to a semiconductor within semiconductors before the appearance of graphene. A brief

  13. 3>2>1: Investigation of Single Particle Particle and Many Body Physics in Dual-Gated 1,2,3 Layers of Graphene

    E-Print Network [OSTI]

    Velasco, Jairo

    2012-01-01

    were grown by atomic layer deposition, image from . Fig 3.3:HfO 2 was grown by atomic layer deposition, image from c.HfO 2 was grown by atomic layer deposition, image from c.

  14. Color stable manganese-doped phosphors

    DOE Patents [OSTI]

    Lyons, Robert Joseph; Setlur, Anant Achyut; Deshpande, Anirundha Rajendra; Grigorov, Ljudmil Slavchev

    2014-04-29

    A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor material radiationally coupled to the light source. The phosphor material includes a color-stable Mn.sup.+4 doped phosphor prepared by a process including providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof.

  15. Iron (III) Chloride doping of large-area chemical vapor deposition graphene

    E-Print Network [OSTI]

    Song, Yi, S.M. Massachusetts Institute of Technology

    2013-01-01

    Chemical doping is an effective method of reducing the sheet resistance of graphene. This thesis aims to develop an effective method of doping large area Chemical Vapor Deposition (CVD) graphene using Iron (III) Chloride ...

  16. CO Oxidation at the Interface between Doped CeO2 and Supported Au Nanoclusters

    E-Print Network [OSTI]

    Henkelman, Graeme

    nanoclusters (NCs) supported on either CeO2 or doped (X-Ce)O2 (X = Au, Pt, Pd, Ti, Ru, Zr) show that dopingCO Oxidation at the Interface between Doped CeO2 and Supported Au Nanoclusters Hyun You Kim, we study the e ect of doping on CO oxidation catalyzed by CeO2-supported Au13 NCs and, especially, CO

  17. Air-Stable Surface Charge Transfer Doping of MoS2 by Benzyl Daisuke Kiriya,,,

    E-Print Network [OSTI]

    Javey, Ali

    Air-Stable Surface Charge Transfer Doping of MoS2 by Benzyl Viologen Daisuke Kiriya,,,§ Mahmut Information ABSTRACT: Air-stable doping of transition metal dichalcogenides is of fundamental importance. The n-doped samples exhibit excellent stability in both ambient air and vacuum. Notably, we obtained

  18. Electron-lattice coupling parameters and oscillator strengths of cerium-doped lutetium oxyorthosilicate

    E-Print Network [OSTI]

    Electron-lattice coupling parameters and oscillator strengths of cerium-doped lutetium absorption of single-crystal, cerium-doped lutetium oxyorthosilicate has been carefully measured properties and luminescence mechanisms of cerium-doped lutetium oxyorthosilicate Lu2SiO5:Ce, here- after

  19. Detection of atomic spin labels in a lipid bi-layer using a single-spin nanodiamond probe

    E-Print Network [OSTI]

    Kaufmann, Stefan; Hall, Liam T; Perunicic, Viktor; Senn, Philipp; Steinert, Steffen; McGuinness, Liam P; Johnson, Brett C; Ohshima, Takeshi; Caruso, Frank; Wrachtrup, Joerg; Scholten, Robert E; Mulvaney, Paul; Hollenberg, Lloyd C L

    2013-01-01

    Magnetic field fluctuations arising from fundamental spins are ubiquitous in nanoscale biology, and are a rich source of information about the processes that generate them. However, the ability to detect the few spins involved without averaging over large ensembles has remained elusive. Here we demonstrate the detection of gadolinium spin labels in an artificial cell membrane under ambient conditions using a single-spin nanodiamond sensor. Changes in the spin relaxation time of the sensor located in the lipid bilayer were optically detected and found to be sensitive to near-individual proximal gadolinium atomic labels. The detection of such small numbers of spins in a model biological setting, with projected detection times of one second, opens a new pathway for in-situ nanoscale detection of dynamical processes in biology.

  20. Application of a Free Energy Landscape Approach to Study Tension Dependent Bilayer Tubulation Mediated by Curvature Inducing Proteins

    E-Print Network [OSTI]

    Tourdot, Richard W; Baumgart, Tobias; Radhakrishnan, Ravi

    2015-01-01

    We investigate the phenomenon of protein induced tubulation of lipid bilayer membranes within a continuum framework using Monte Carlo simulations coupled with the Widom insertion technique to compute excess chemical potentials. Tubular morphologies are spontaneously formed when the density and the curvature-field strength of the membrane bound proteins exceed their respective thresholds and this transition is marked by a sharp drop in the excess chemical potential. We find that the planar to tubular transition can be described by a micellar model and that the corresponding free energy barrier increases with increase in the curvature-field strength, (i.e. of protein-membrane interactions), and also with increase in membrane tension.

  1. Doping-assisted defect control in compound semiconductors

    DOE Patents [OSTI]

    Specht, Petra; Weber, Eicke R.; Weatherford, Todd Russell

    2006-07-11

    The present invention relates to the production of thin film epilayers of III–V and other compounds with acceptor doping wherein the acceptor thermally stabilizes the epilayer, stabilize the naturally incorporated native defect population and therewith maintain the epilayer's beneficial properties upon annealing among other advantageous effects. In particular, balanced doping in which the acceptor concentration is similar to (but does not exceed) the antisite defects in the as-grown material is shown to be particularly advantageous in providing thermal stability, high resistivity and ultrashort trapping times. In particular, MBE growth of LT-GaAs epilayers with balanced Be doping is described in detail. The growth conditions greatly enhance the materials reproducibility (that is, the yield in processed devices). Such growth techniques can be transferred to other III–V materials if the growth conditions are accurately reproduced. Materials produced herein also demonstrate advantages in reproducibility, reliability and radiation hardening.

  2. Stable doping of carbon nanotubes via molecular self assembly

    SciTech Connect (OSTI)

    Lee, B.; Chen, Y.; Podzorov, V.; Cook, A.; Zakhidov, A.

    2014-10-14

    We report a novel method for stable doping of carbon nanotubes (CNT) based on methods of molecular self assembly. A conformal growth of a self-assembled monolayer of fluoroalkyl trichloro-silane (FTS) at CNT surfaces results in a strong increase of the sheet conductivity of CNT electrodes by 60–300%, depending on the CNT chirality and composition. The charge carrier mobility of undoped partially aligned CNT films was independently estimated in a field-effect transistor geometry (~100 cm²V?¹s?¹). The hole density induced by the FTS monolayer in CNT sheets is estimated to be ~1.8 ×10¹?cm?². We also show that FTS doping of CNT anodes greatly improves the performance of organic solar cells. This large and stable doping effect, easily achieved in large-area samples, makes this approach very attractive for applications of CNTs in transparent and flexible electronics.

  3. Doping of carbon foams for use in energy storage devices

    DOE Patents [OSTI]

    Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Morrison, Robert L. (Modesto, CA); Kaschmitter, James L. (Pleasanton, CA)

    1994-01-01

    A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located therebetween. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery.

  4. Doping of carbon foams for use in energy storage devices

    DOE Patents [OSTI]

    Mayer, S.T.; Pekala, R.W.; Morrison, R.L.; Kaschmitter, J.L.

    1994-10-25

    A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located there between. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery. 3 figs.

  5. Theory of the spontaneous buckling of doped graphene

    E-Print Network [OSTI]

    Doron Gazit

    2009-03-11

    Graphene is a realization of an esoteric class of materials -- electronic crystalline membranes. We study the interplay between the free electrons and the two-dimensional crystal, and find that it induces a substantial effect on the elastic structure of the membrane. For the hole-doped membrane, in particular, we predict a spontaneous buckling. In addition, attenuation of elastic waves is expected, due to the effect of corrugations on the bulk modulus. These discoveries have a considerable magnitude in graphene, affecting both its mesoscopic structure, and its electrical resistivity, which has an inherent asymmetry between hole- and electron-doped graphene.

  6. Engineering shallow spins in diamond with nitrogen delta-doping

    SciTech Connect (OSTI)

    Ohno, Kenichi; Joseph Heremans, F.; Bassett, Lee C.; Myers, Bryan A.; Toyli, David M.; Bleszynski Jayich, Ania C.; Palmstrom, Christopher J.; Awschalom, David D.

    2012-08-20

    We demonstrate nanometer-precision depth control of nitrogen-vacancy (NV) center creation near the surface of synthetic diamond using an in situ nitrogen delta-doping technique during plasma-enhanced chemical vapor deposition. Despite their proximity to the surface, doped NV centers with depths (d) ranging from 5 to 100 nm display long spin coherence times, T{sub 2} > 100 {mu}s at d = 5 nm and T{sub 2} > 600 {mu}s at d {>=} 50 nm. The consistently long spin coherence observed in such shallow NV centers enables applications such as atomic-scale external spin sensing and hybrid quantum architectures.

  7. Single-poly EEPROM cell with lightly doped MOS capacitors

    DOE Patents [OSTI]

    Riekels, James E. (New Hope, MN); Lucking, Thomas B. (Maple Grove, MN); Larsen, Bradley J. (Mound, MN); Gardner, Gary R. (Golden Valley, MN)

    2008-05-27

    An Electrically Erasable Programmable Read Only Memory (EEPROM) memory cell and a method of operation are disclosed for creating an EEPROM memory cell in a standard CMOS process. A single polysilicon layer is used in combination with lightly doped MOS capacitors. The lightly doped capacitors employed in the EEPROM memory cell can be asymmetrical in design. Asymmetrical capacitors reduce area. Further capacitance variation caused by inversion can also be reduced by using multiple control capacitors. In addition, the use of multiple tunneling capacitors provides the benefit of customized tunneling paths.

  8. Tuning nucleation density of metal island with charge doping of graphene substrate

    SciTech Connect (OSTI)

    Ming, Wenmei; Liu, Feng

    2014-08-18

    We have demonstrated that the island nucleation in the initial stage of epitaxial thin film growth can be tuned by substrate surface charge doping. This charge effect was investigated using spin density functional theory calculation in Fe-deposition on graphene substrate as an example. It was found that hole-doping can noticeably increase both Fe-adatom diffusion barrier and Fe inter-adatom repulsion energy occurring at intermediate separation, whereas electron-doping can decrease Fe-adatom diffusion barrier but only slightly modify inter-adatom repulsion energy. Further kinetic Monte Carlo simulation showed that the nucleation island number density can be increased up to six times larger under hole-doping and can be decreased down to ten times smaller under electron doping than that without doping. Our findings indicate a route to tailor the growth morphology of magnetic metal nanostructure for spintronics and plasmonic applications via surface charge doping.

  9. Controlled nanoscale doping of semiconductors via molecular monolayers

    E-Print Network [OSTI]

    California at Berkeley, University of

    -limiting and self-assembly processes where surface and chemical phenomena guide the synthesis and fabrication) the formation of self-assembled monolayers of dopant-containing molecules on the surface of crystalline SiARTICLES Controlled nanoscale doping of semiconductors via molecular monolayers JOHNNY C. HO1

  10. Energy transfer in erbium doped optical waveguides based on silicon

    E-Print Network [OSTI]

    Polman, Albert

    .6 Outlook 27 #12;3 Co-operative upconversion as the gain limiting factor in Er doped miniature Al2O3 optical 5.5.3 Model calculations 64 5.6 Implications for solar cell and infrared detector design 67 5

  11. Spin-phonon coupling in scandium doped gallium ferrite

    SciTech Connect (OSTI)

    Chakraborty, Keka R. E-mail: smyusuf@barc.gov.in; Mukadam, M. D.; Basu, S.; Yusuf, S. M. E-mail: smyusuf@barc.gov.in; Paul, Barnita; Roy, Anushree; Grover, Vinita; Tyagi, A. K.

    2015-03-28

    We embarked on a study of Scandium (Sc) doped (onto Ga site) gallium ferrite (GaFeO{sub 3}) and found remarkable magnetic properties. In both doped as well as parent compounds, there were three types of Fe{sup 3+} ions (depending on the symmetry) with the structure conforming to space group Pna2{sub 1} (Sp. Grp. No. 33) below room temperature down to 5?K. We also found that all Fe{sup 3+} ions occupy octahedral sites, and carry high spin moment. For the higher Sc substituted sample (Ga{sub 1?x}Sc{sub x}FeO{sub 3}: x?=?0.3), a canted magnetic ordered state is found. Spin-phonon coupling below Néel temperature was observed in doped compounds. Our results indicated that Sc doping in octahedral site modifies spin-phonon interactions of the parent compound. The spin-phonon coupling strength was estimated for the first time in these Sc substituted compounds.

  12. Process for fabricating doped zinc oxide microsphere gel

    DOE Patents [OSTI]

    Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

    1991-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  13. Chemical vapor deposition of fluorine-doped zinc oxide

    DOE Patents [OSTI]

    Gordon, Roy G. (Cambridge, MA); Kramer, Keith (Avon Lake, OH); Liang, Haifan (Santa Clara, CA)

    2000-06-06

    Fims of fluorine-doped zinc oxide are deposited from vaporized precursor compounds comprising a chelate of a dialkylzinc, such as an amine chelate, an oxygen source, and a fluorine source. The coatings are highly electrically conductive, transparent to visible light, reflective to infrared radiation, absorbing to ultraviolet light, and free of carbon impurity.

  14. Iodine Doped P3AT Structure 5.1 Introduction

    E-Print Network [OSTI]

    Winokur, Michael

    samples. The study of various intercalated structures by x­ray diffraction of polymer systems has a number doped P3AT films, the Osaka group has investigated a number of different dopants (NF \\Gamma 4 , BF \\Gamma 4 , AsF \\Gamma 6 , p­TS and Iodine) in P3ATs with side chain lengths ranging from butyl

  15. High capacity nickel battery material doped with alkali metal cations

    DOE Patents [OSTI]

    Jackovitz, John F. (Monroeville, PA); Pantier, Earl A. (Penn Hills, PA)

    1982-05-18

    A high capacity battery material is made, consisting essentially of hydrated Ni(II) hydroxide, and about 5 wt. % to about 40 wt. % of Ni(IV) hydrated oxide interlayer doped with alkali metal cations selected from potassium, sodium and lithium cations.

  16. RICH METHANE PREMIXED LAMINAR FLAMES DOPED BY LIGHT UNSATURATED HYDROCARBONS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    RICH METHANE PREMIXED LAMINAR FLAMES DOPED BY LIGHT UNSATURATED HYDROCARBONS PART I: ALLENE developed in our laboratory for the reactions of C3-C4 unsaturated hydrocarbons. The main reaction pathways2007 #12;3 INTRODUCTION Soots and polyaromatic hydrocarbons (PAH), which are present in the exhaust gas

  17. ACCURATE EXTRACTION OF DOPING PROFILES FROM ELECTROCHEMICAL CAPACITANCE VOLTAGE MEASUREMENTS

    E-Print Network [OSTI]

    of electrical properties of semiconductor devices. In contrast, the ECV method provides only the electrically concentration, the dissipation factor or the Debye length of the measured material. Using fully automated. 1 INTRODUCTION "Doping profile engineering" is a key word if an optimization of semiconductor

  18. Process for fabricating doped zinc oxide microsphere gel

    DOE Patents [OSTI]

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1991-11-05

    Disclosed are a new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  19. Doped tantalum oxide high K dielectric thin films 

    E-Print Network [OSTI]

    Donnelly, Joseph Patrick

    2000-01-01

    , it was doped with varying amounts of titanium oxide, aluminum oxide and silicon dioxide. The composite oxide films were deposited by reactive radio frequency (RF) cc-sputtering of two targets in a variety of oxygen and argon feed gas mixtures. The targets used...

  20. Systematics of Pure and Doped He-4 Clusters 

    E-Print Network [OSTI]

    Chin, Siu A.; KROTSCHECK, E.

    1995-01-01

    Optimized variational calculations have been carried out for pure and doped clusters of He-4 atoms up to a cluster size of N=1000 particles. For small cluster sizes with less than or equal to 112 particles, where comparisons with existing diffusion...

  1. Metal-doped semiconductor nanoparticles and methods of synthesis thereof

    DOE Patents [OSTI]

    Ren, Zhifeng (Newton, MA); Chen, Gang (Carlisle, MA); Poudel, Bed (West Newton, MA); Kumar, Shankar (Newton, MA); Wang, Wenzhong (Beijing, CN); Dresselhaus, Mildred (Arlington, MA)

    2009-09-08

    The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

  2. Macro- and microscopic properties of strontium doped indium oxide

    SciTech Connect (OSTI)

    Nikolaenko, Y. M.; Kuzovlev, Y. E.; Medvedev, Y. V.; Mezin, N. I.; Fasel, C.; Gurlo, A.; Schlicker, L.; Bayer, T. J. M.; Genenko, Y. A.

    2014-07-28

    Solid state synthesis and physical mechanisms of electrical conductivity variation in polycrystalline, strontium doped indium oxide In{sub 2}O{sub 3}:(SrO){sub x} were investigated for materials with different doping levels at different temperatures (T?=?20–300?°C) and ambient atmosphere content including humidity and low pressure. Gas sensing ability of these compounds as well as the sample resistance appeared to increase by 4 and 8 orders of the magnitude, respectively, with the doping level increase from zero up to x?=?10%. The conductance variation due to doping is explained by two mechanisms: acceptor-like electrical activity of Sr as a point defect and appearance of an additional phase of SrIn{sub 2}O{sub 4}. An unusual property of high level (x?=?10%) doped samples is a possibility of extraordinarily large and fast oxygen exchange with ambient atmosphere at not very high temperatures (100–200?°C). This peculiarity is explained by friable structure of crystallite surface. Friable structure provides relatively fast transition of samples from high to low resistive state at the expense of high conductance of the near surface layer of the grains. Microscopic study of the electro-diffusion process at the surface of oxygen deficient samples allowed estimation of the diffusion coefficient of oxygen vacancies in the friable surface layer at room temperature as 3?×?10{sup ?13}?cm{sup 2}/s, which is by one order of the magnitude smaller than that known for amorphous indium oxide films.

  3. Scattering Density Profile Model of POPG Bilayers as Determined by Molecular Dynamics Simulations and Small-Angle Neutron and X-ray Scattering Experiments

    SciTech Connect (OSTI)

    Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Holland, B [University of Guelph; Gray, C.G [University of Guelph; Tomberli, B [Brandon University; Katsaras, John [ORNL

    2012-01-01

    We combine molecular dynamics (MD) simulations and experiment, both small-angle neutron (SANS) and small-angle X-ray scattering (SAXS), to determine the precise structure of bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG), a lipid commonly encountered in bacterial membranes. Experiment and simulation are used to develop a one-dimensional scattering density profile (SDP) model suitable for the analysis of experimental data. The joint refinement of such data (i.e., SANS and SAXS) results in the area per lipid that is then used in the fixed-area simulations. In the final step, the direct comparison of simulated-to-experimental data gives rise to the detailed structure of POPG bilayers. From these studies we conclude that POPG s molecular area is 66.0 +/- 1.3 ^2, its overall bilayer thickness is 36.7 +/- 0.7 , and its hydrocarbon region thickness is 27.9 ( 0.6 , assuming a simulated value of 1203 ^3 for the total lipid volume.

  4. Monte Carlo Study of Strongly-Interacting Degenerate Fermions: a Model for Voltage-Biased Bilayer Graphene

    E-Print Network [OSTI]

    Wes Armour; Simon Hands; Costas Strouthos

    2013-02-07

    We formulate a model of N_f=4 flavors of relativistic fermion in 2+1d in the presence of a chemical potential mu coupled to two flavor doublets with opposite sign, akin to isopsin chemical potential in QCD. This is argued to be an effective theory for low energy electronic excitations in bilayer graphene, in which an applied voltage between the layers ensures equal populations of particles on one layer and holes on the other. The model is then reformulated on a spacetime lattice using staggered fermions, and in the absence of a sign problem, simulated using an orthodox hybrid Monte Carlo algorithm. With the coupling strength chosen to be close to a quantum critical point believed to exist for N_f

  5. Nanosecond molecular relaxations in lipid bilayers studied by high energy resolution neutron scattering and in-situ diffraction

    E-Print Network [OSTI]

    Maikel C. Rheinstädter; Tilo Seydel; Tim Salditt

    2006-07-20

    We report a high energy-resolution neutron backscattering study to investigate slow motions on nanosecond time scales in highly oriented solid supported phospholipid bilayers of the model system DMPC -d54 (deuterated 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine), hydrated with heavy water. Wave vector resolved quasi-elastic neutron scattering (QENS) is used to determine relaxation times $\\tau$, which can be associated with different molecular components, i.e., the lipid acyl chains and the interstitial water molecules in the different phases of the model membrane system. The inelastic data are complemented both by energy resolved and energy integrated in-situ diffraction. From a combined analysis of the inelastic data in the energy and time domain, the respective character of the relaxation, i.e., the exponent of the exponential decay is also determined. From this analysis we quantify two relaxation processes. We associate the fast relaxation with translational diffusion of lipid and water molecules while the slow process likely stems from collective dynamics.

  6. Electrical properties of nitrogen-doped float-zone silicon. Interim report, March-1984-March 1985

    SciTech Connect (OSTI)

    O'Leary, M.A.; Mitchel, W.C.

    1985-07-01

    Examination of nitrogen doped float zone silicon indicates that electrical properties are similiar to commerical Czochralski material. This material deserves further consideration for use in high power device and intrinsic infrared detector applications. Temperature-dependent Hall-effect measurements were made on as-received and neutron-transmutation-doped (NTD) sample of a nitrogen-doped float-zone silicon crystal to determine its electrical properties. Samples were studied in both as-received state and after various high-temperature anneals. Results were compared with commerical n-type Czochralski silicon and conventional neutron doped float zone silcion. Undoped, annealed samples of Si:N showed signs of inhomogeneities were not seen in lightly NTD's and annealed nitrogen-doped material, indicating that even light doping will mask effects of the proposed precipitation. No evidence was detected for any electrically active level that could be directly related to the nitrogen.

  7. Control of work function of graphene by plasma assisted nitrogen doping

    SciTech Connect (OSTI)

    Akada, Keishi; Terasawa, Tomo-o; Imamura, Gaku; Obata, Seiji; Saiki, Koichiro, E-mail: saiki@k.u-tokyo.ac.jp [Department of Complexity Science and Engineering, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8561 (Japan)

    2014-03-31

    Nitrogen doping is expected to provide several intriguing properties to graphene. Nitrogen plasma treatment to defect-free and defective highly oriented pyrolytic graphite (HOPG) samples causes doping of nitrogen atom into the graphene layer. Nitrogen atoms are initially doped at a graphitic site (inside the graphene) for the defect-free HOPG, while doping to a pyridinic or a pyrrolic site (edge of the graphene) is dominant for the defective HOPG. The work function of graphene correlates strongly with the site and amount of doped nitrogen. Nitrogen atoms doped at a graphitic site lower the work function, while nitrogen atoms at a pyridinic or a pyrrolic site increase the work function. Control of plasma treatment time and the amount of initial defect could change the work function of graphite from 4.3?eV to 5.4?eV, which would open a way to tailor the nature of graphene for various industrial applications.

  8. Polarization doping and the efficiency of III-nitride optoelectronic devices

    SciTech Connect (OSTI)

    Kivisaari, Pyry; Oksanen, Jani; Tulkki, Jukka [Department of Biomedical Engineering and Computational Science, Aalto University, P.O. Box 12200, FI-00076 Aalto (Finland)] [Department of Biomedical Engineering and Computational Science, Aalto University, P.O. Box 12200, FI-00076 Aalto (Finland)

    2013-11-18

    The intrinsic polarization is generally considered a nuisance in III-nitride devices, but recent studies have shown that it can be used to enhance p- and n-type conductivity and even to replace impurity doping. We show by numerical simulations that polarization-doped light-emitting diode (LED) structures have a significant performance advantage over conventional impurity-doped LED structures. Our results indicate that polarization doping decreases electric fields inside the active region and potential barriers in the depletion region, as well as the magnitude of the quantum-confined Stark effect. The simulations also predict at least an order of magnitude increase in the current density corresponding to the maximum efficiency (i.e., smaller droop) as compared to impurity-doped structures. The obtained high doping concentrations could also enable, e.g., fabrication of III-N resonant tunneling diodes and improved ohmic contacts.

  9. Systematic study of doping dependence on linear magnetoresistance in p-PbTe

    SciTech Connect (OSTI)

    Schneider, J. M.; Chitta, V. A.; Oliveira, N. F.; Peres, M. L. Castro, S. de; Soares, D. A. W.; Wiedmann, S.; Zeitler, U.; Abramof, E.; Rappl, P. H. O.; Mengui, U. A.

    2014-10-20

    We report on a large linear magnetoresistance effect observed in doped p-PbTe films. While undoped p-PbTe reveals a sublinear magnetoresistance, p-PbTe films doped with BaF{sub 2} exhibit a transition to a nearly perfect linear magnetoresistance behaviour that is persistent up to 30?T. The linear magnetoresistance slope ?R/?B is to a good approximation, independent of temperature. This is in agreement with the theory of Quantum Linear Magnetoresistance. We also performed magnetoresistance simulations using a classical model of linear magnetoresistance. We found that this model fails to explain the experimental data. A systematic study of the doping dependence reveals that the linear magnetoresistance response has a maximum for small BaF{sub 2} doping levels and diminishes rapidly for increasing doping levels. Exploiting the huge impact of doping on the linear magnetoresistance signal could lead to new classes of devices with giant magnetoresistance behavior.

  10. Process for fabricating device structures for real-time process control of silicon doping

    DOE Patents [OSTI]

    Weiner, Kurt H. (San Jose, CA)

    2001-01-01

    Silicon device structures designed to allow measurement of important doping process parameters immediately after the doping step has occurred. The test structures are processed through contact formation using standard semiconductor fabrication techniques. After the contacts have been formed, the structures are covered by an oxide layer and an aluminum layer. The aluminum layer is then patterned to expose the contact pads and selected regions of the silicon to be doped. Doping is then performed, and the whole structure is annealed with a pulsed excimer laser. But laser annealing, unlike standard annealing techniques, does not effect the aluminum contacts because the laser light is reflected by the aluminum. Once the annealing process is complete, the structures can be probed, using standard techniques, to ascertain data about the doping step. Analysis of the data can be used to determine probable yield reductions due to improper execution of the doping step and thus provide real-time feedback during integrated circuit fabrication.

  11. High gain photoconductive semiconductor switch having tailored doping profile zones

    DOE Patents [OSTI]

    Baca, Albert G. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Mar, Alan (Albuquerque, NM); Zutavern, Fred J (Albuquerque, NM); Hjalmarson, Harold P. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM); Zipperian, Thomas E. (Edgewood, NM); O'Malley, Martin W. (Edgewood, NM); Helgeson, Wesley D. (Albuquerque, NM); Denison, Gary J. (Sandia Park, NM); Brown, Darwin J. (Albuquerque, NM); Sullivan, Charles T. (Albuquerque, NM); Hou, Hong Q. (Albuquerque, NM)

    2001-01-01

    A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

  12. Imaging doped silicon test structures using low energy electron microscopy.

    SciTech Connect (OSTI)

    Nakakura, Craig Yoshimi; Anderson, Meredith Lynn; Kellogg, Gary Lee

    2010-01-01

    This document is the final SAND Report for the LDRD Project 105877 - 'Novel Diagnostic for Advanced Measurements of Semiconductor Devices Exposed to Adverse Environments' - funded through the Nanoscience to Microsystems investment area. Along with the continuous decrease in the feature size of semiconductor device structures comes a growing need for inspection tools with high spatial resolution and high sample throughput. Ideally, such tools should be able to characterize both the surface morphology and local conductivity associated with the structures. The imaging capabilities and wide availability of scanning electron microscopes (SEMs) make them an obvious choice for imaging device structures. Dopant contrast from pn junctions using secondary electrons in the SEM was first reported in 1967 and more recently starting in the mid-1990s. However, the serial acquisition process associated with scanning techniques places limits on the sample throughput. Significantly improved throughput is possible with the use of a parallel imaging scheme such as that found in photoelectron emission microscopy (PEEM) and low energy electron microscopy (LEEM). The application of PEEM and LEEM to device structures relies on contrast mechanisms that distinguish differences in dopant type and concentration. Interestingly, one of the first applications of PEEM was a study of the doping of semiconductors, which showed that the PEEM contrast was very sensitive to the doping level and that dopant concentrations as low as 10{sup 16} cm{sup -3} could be detected. More recent PEEM investigations of Schottky contacts were reported in the late 1990s by Giesen et al., followed by a series of papers in the early 2000s addressing doping contrast in PEEM by Ballarotto and co-workers and Frank and co-workers. In contrast to PEEM, comparatively little has been done to identify contrast mechanisms and assess the capabilities of LEEM for imaging semiconductor device strictures. The one exception is the work of Mankos et al., who evaluated the impact of high-throughput requirements on the LEEM designs and demonstrated new applications of imaging modes with a tilted electron beam. To assess its potential as a semiconductor device imaging tool and to identify contrast mechanisms, we used LEEM to investigate doped Si test structures. In section 2, Imaging Oxide-Covered Doped Si Structures Using LEEM, we show that the LEEM technique is able to provide reasonably high contrast images across lateral pn junctions. The observed contrast is attributed to a work function difference ({Delta}{phi}) between the p- and n-type regions. However, because the doped regions were buried under a thermal oxide ({approx}3.5 nm thick), e-beam charging during imaging prevented quantitative measurements of {Delta}{phi}. As part of this project, we also investigated a series of similar test structures in which the thermal oxide was removed by a chemical etch. With the oxide removed, we obtained intensity-versus-voltage (I-V) curves through the transition from mirror to LEEM mode and determined the relative positions of the vacuum cutoffs for the differently doped regions. Although the details are not discussed in this report, the relative position in voltage of the vacuum cutoffs are a direct measure of the work function difference ({Delta}{phi}) between the p- and n-doped regions.

  13. Ytterbium-doped borate fluoride laser crystals and lasers

    DOE Patents [OSTI]

    Schaffers, Kathleen I. (Pleasanton, CA); DeLoach, Laura D. (Manteca, CA); Payne, Stephen A. (Castro Valley, CA); Keszler, Douglas A. (Corvallis, OK)

    1997-01-01

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

  14. Direct visualization of atomically precise nitrogen-doped graphene nanoribbons

    SciTech Connect (OSTI)

    Zhang, Yi; Zhang, Yanfang; Li, Geng; Lu, Jianchen; Du, Shixuan, E-mail: sxdu@iphy.ac.cn, E-mail: feng@mpip-mainz.mpg.de; Gao, Hong-Jun [Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Xiao [University of Chinese Academy of Sciences and Institute of Physics, Chinese Academy of Sciences, Beijing 100049 (China); Berger, Reinhard; Feng, Xinliang, E-mail: sxdu@iphy.ac.cn, E-mail: feng@mpip-mainz.mpg.de; Müllen, Klaus [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany)

    2014-07-14

    We have fabricated atomically precise nitrogen-doped chevron-type graphene nanoribbons by using the on-surface synthesis technique combined with the nitrogen substitution of the precursors. Scanning tunneling microscopy and spectroscopy indicate that the well-defined nanoribbons tend to align with the neighbors side-by-side with a band gap of 1.02?eV, which is in good agreement with the density functional theory calculation result. The influence of the high precursor coverage on the quality of the nanoribbons is also studied. We find that graphene nanoribbons with sufficient aspect ratios can only be fabricated at sub-monolayer precursor coverage. This work provides a way to construct atomically precise nitrogen-doped graphene nanoribbons.

  15. Ytterbium-doped borate fluoride laser crystals and lasers

    DOE Patents [OSTI]

    Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.; Keszler, D.A.

    1997-10-14

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM{prime}(BO{sub 3})F, where M, M{prime} are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO{sub 3}F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator. 6 figs.

  16. Method of fabricating optical waveguides by ion implantation doping

    DOE Patents [OSTI]

    Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

    1987-03-24

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

  17. Synthesis of mesoporous NiO doped TiO{sub 2} submicrosphere via spray hydrolysis

    SciTech Connect (OSTI)

    Bahadur, J.; Sen, D.; Prakash, J.; Singh, Ripandeep; Paul, B.; Mazumder, S.; Sathiyamoorthy, D.

    2012-06-05

    NiO doped TiO{sub 2} submicrosphere have been prepared via spray hydrolysis. The doping concentration has been varied form 2 wt% to 15 wt%. Morphology of the submicrospheres has been investigated using small-angle neutron scattering and scanning electron microscopy. Elemental analysis has been carried out by energy dispersive X-ray analysis which confirms the doping concentrations. The mesopores in submicrospheres possess cylindrical morphology.

  18. Antimony-Doped Tin(II) Sulfide Thin Films Prasert Sinsermsuksakul,

    E-Print Network [OSTI]

    always been observed to be a p-type semiconductor. Doping SnS to form an n-type semiconductor would permit the construction of solar cells with p-n homojunctions. This paper reports doping SnS films of photovoltaics. SnS can be doped by Ag13,14 and Cu15 to increase its hole concentration to around 1019 cm-3

  19. Method for measuring the drift mobility in doped semiconductors

    DOE Patents [OSTI]

    Crandall, R.S.

    1982-03-09

    A method for measuring the drift mobility of majority carriers in semiconductors consists of measuring the current transient in a Schottky-barrier device following the termination of a forward bias pulse. An example is given using an amorphous silicon hydrogenated material doped with 0.2% phosphorus. The method is particularly useful with material in which the dielectric relaxation time is shorter than the carrier transit time. It is particularly useful in material useful in solar cells. 10 figs.

  20. Self-doped microphase separated block copolymer electrolyte

    DOE Patents [OSTI]

    Mayes, Anne M. (Waltham, MA); Sadoway, Donald R. (Waltham, MA); Banerjee, Pallab (Boston, MA); Soo, Philip (Cambridge, MA); Huang, Biying (Cambridge, MA)

    2002-01-01

    A polymer electrolyte includes a self-doped microphase separated block copolymer including at least one ionically conductive block and at least one second block that is immiscible in the ionically conductive block, an anion immobilized on the polymer electrolyte and a cationic species. The ionically conductive block provides a continuous ionically conductive pathway through the electrolyte. The electrolyte may be used as an electrolyte in an electrochemical cell.

  1. Method for measuring the drift mobility in doped semiconductors

    DOE Patents [OSTI]

    Crandall, Richard S. (Princeton, NJ)

    1982-01-01

    A method for measuring the drift mobility of majority carriers in semiconductors consists of measuring the current transient in a Schottky-barrier device following the termination of a forward bias pulse. An example is given using an amorphous silicon hydrogenated material doped with 0.2% phosphorous. The method is particularly useful with material in which the dielectric relaxation time is shorter than the carrier transit time. It is particularly useful in material useful in solar cells.

  2. Oxidation of Al doped Au clusters: A first principles study

    SciTech Connect (OSTI)

    Rajesh, Chinagandham [RMC, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Majumder, Chiranjib [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2009-06-21

    Using first principles method we report the oxidation of Al doped Au clusters. This work is divided into two parts: (i) the equilibrium structures and stability of Al doped Au{sub n-1} clusters (n=2-7,21) and (ii) the interaction of O{sub 2} with stable clusters. The calculations are performed using the plane wave pseudopotential approach under the density functional theory and generalized gradient approximation for the exchange and correlation functional. The optimized geometries of Au{sub n-1}Al clusters indicate that the substitution of Au by Al results an early onset of three-dimensional structures from tetramer onwards. This is different from the results of transition metal doped Au clusters, where the planar conformation of Au clusters retains up to heptamer. The stability of Au{sub n-1}Al clusters has been analyzed based on the binding energy, second difference in energy, and the energy gaps between the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Based on the energetics, the Au{sub 3}Al and Au{sub 5}Al clusters are found to have extraordinary stability. The oxidation mechanism of Al doped Au clusters have been studied by the interaction of O{sub 2} with Al, Au, AuAl, Au{sub 3}Al, and Au{sub 20}Al clusters. It is found that the oxidation of Au{sub n-1}Al clusters undergoes via dissociative mechanism, albeit significant charge transfer from Al to Au. Moreover, the O{sub 2} molecule prefers to attach at the Al site rather than at the Au site.

  3. High gain, low noise, fully complementary logic inverter based on bi-layer WSe{sub 2} field effect transistors

    SciTech Connect (OSTI)

    Das, Saptarshi; Roelofs, Andreas; Dubey, Madan

    2014-08-25

    In this article, first, we show that by contact work function engineering, electrostatic doping and proper scaling of both the oxide thickness and the flake thickness, high performance p- and n-type WSe{sub 2} field effect transistors (FETs) can be realized. We report record high drive current of 98??A/?m for the electron conduction and 110 ?A/?m for the hole conduction in Schottky barrier WSe{sub 2} FETs. Then, we combine high performance WSe{sub 2} PFET with WSe{sub 2} NFET in double gated transistor geometry to demonstrate a fully complementary logic inverter. We also show that by adjusting the threshold voltages for the NFET and the PFET, the gain and the noise margin of the inverter can be significantly enhanced. The maximum gain of our chemical doping free WSe{sub 2} inverter was found to be ?25 and the noise margin was close to its ideal value of ?2.5?V for a supply voltage of V{sub DD}?=?5.0?V.

  4. Theory of nitrogen doping of carbon nanoribbons: Edge effects

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jiang, Jie; Turnbull, Joseph; Lu, Wenchang; Oak Ridge National Lab.; Boguslawski, Piotr; Univ. of Warsaw; Bernholc, J.; Oak Ridge National Lab.

    2012-01-01

    Nitrogen doping of a carbon nanoribbon is profoundly affected by its one-dimensional character, symmetry, and interaction with edge states. Using state-of-the-art ab initio calculations, including hybrid exact-exchange density functional theory, we find that, for N-doped zigzag ribbons, the electronic properties are strongly dependent upon sublattice effects due to the non-equivalence of the two sublattices. For armchair ribbons, N-doping effects are different depending upon the ribbon family: for families 2 and 0, the N-induced levels are in the conduction band, while for family 1 the N levels are in the gap. In zigzag nanoribbons, nitrogen close to the edge is amore »deep center, while in armchair nanoribbons its behavior is close to an effective-mass-like donor with the ionization energy dependent on the value of the band gap. In chiral nanoribbons, we find strong dependence of the impurity level and formation energy upon the edge position of the dopant, while such site-specificity is not manifested in the magnitude of the magnetization.« less

  5. Ca2+-Doped CeBr3 Scintillating Materials

    SciTech Connect (OSTI)

    Guss, Paul; Foster, Michael E.; Wong, Bryan M.; Doty, F. Patrick; Shah, Kanai; Squillante, Michael R.; Shirwadkar, Urmila; Hawrami, Rastgo; Tower, Josh; Yuan, Ding

    2014-01-21

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide, their commercial availability and application are limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. This investigation employed aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was used as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were studied using the density functional theory within the generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  6. Doping of germanium and silicon crystals with non-hydrogenic acceptors for far infrared lasers

    DOE Patents [OSTI]

    Haller, Eugene E. (Berkeley, CA); Brundermann, Erik (Berlin, DE)

    2000-01-01

    A method for doping semiconductors used for far infrared lasers with non-hydrogenic acceptors having binding energies larger than the energy of the laser photons. Doping of germanium or silicon crystals with beryllium, zinc or copper. A far infrared laser comprising germanium crystals doped with double or triple acceptor dopants permitting the doped laser to be tuned continuously from 1 to 4 terahertz and to operate in continuous mode. A method for operating semiconductor hole population inversion lasers with a closed cycle refrigerator.

  7. SU-8 doped and encapsulated n-type graphene nanomesh with high air stability

    SciTech Connect (OSTI)

    Al-Mumen, Haider [Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States) [Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Electrical Engineering, University of Babylon, Babylon (Iraq); Dong, Lixin; Li, Wen, E-mail: wenli@egr.msu.edu [Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States)] [Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States)

    2013-12-02

    N-type doping of graphene with long-term chemical stability in air represents a significant challenge for practical application of graphene electronics. This paper reports a reversible doping method to achieve highly stable n-type graphene nanomeshes, in which the SU-8 photoresist simultaneously serves as an effective electron dopant and an excellent encapsulating layer. The chemically stable n-type characteristics of the SU-8 doped graphene were evaluated in air using their Raman spectra, electrical transport properties, and electronic band structures. The SU-8 doping does minimum damage to the hexagonal carbon lattice of graphene and is completely reversible by removing the uncrosslinked SU-8 resist.

  8. Method of manufacturing semiconductor having group II-group VI compounds doped with nitrogen

    DOE Patents [OSTI]

    Compaan, Alvin D.; Price, Kent J.; Ma, Xianda; Makhratchev, Konstantin

    2005-02-08

    A method of making a semiconductor comprises depositing a group II-group VI compound onto a substrate in the presence of nitrogen using sputtering to produce a nitrogen-doped semiconductor. This method can be used for making a photovoltaic cell using sputtering to apply a back contact layer of group II-group VI compound to a substrate in the presence of nitrogen, the back coating layer being doped with nitrogen. A semiconductor comprising a group II-group VI compound doped with nitrogen, and a photovoltaic cell comprising a substrate on which is deposited a layer of a group II-group VI compound doped with nitrogen, are also included.

  9. Doping-induced strain and relaxation of Al-doped 4H-SiC homoepitaxial layers

    SciTech Connect (OSTI)

    Huh, S.W.; Chung, H.J.; Benamara, M.; Skowronski, M.; Sumakeris, J.J.; Paisley, M.J.

    2004-10-15

    Aluminum-doped 4H-SiC epilayers with Al concentrations in the 7.4x10{sup 18}-3.8x10{sup 20} cm{sup -3} range were deposited on off-orientation (0001) wafers by chemical vapor deposition method and analyzed using high-resolution x-ray diffraction, transmission electron microscopy, and KOH etching. Reciprocal space maps of (0008) reflection revealed two distinct peaks originating from the substrate and doped epilayer. For Al concentration below 3.3x10{sup 20} cm{sup -3}, 10 {mu}m thick layers were fully strained with the a-lattice parameter of the layer matching that of the substrate. The equilibrium c-lattice parameter change versus doping was determined to be 1.3{+-}0.3x10{sup -24} cm{sup 3}. The basal planes of the epilayers were tilted in respect to the substrate in the direction of the offcut with the tilt magnitude proportional to the doping concentration. The 10 {mu}m thick layers with Al concentration above 3.3x10{sup 20} cm{sup -3} underwent partial relaxation. The a-lattice parameter of the epilayer was higher than that of the substrate, the width of {omega} and 2{theta} scans of (0008) x-ray peaks broadened by a factor of 2 compared to strained layers, and the threading dislocation density increased by several orders of magnitude. Since no inclusions have been found in the relaxed epilayer, we interpret the above changes as due to strain relaxation by nucleation of dislocations.

  10. Electrically actuatable doped polymer flakes and electrically addressable optical devices using suspensions of doped polymer flakes in a fluid host

    DOE Patents [OSTI]

    Trajkovska-Petkoska, Anka; Jacobs, Stephen D.; Marshall, Kenneth L.; Kosc, Tanya Z.

    2010-05-11

    Doped electrically actuatable (electrically addressable or switchable) polymer flakes have enhanced and controllable electric field induced motion by virtue of doping a polymer material that functions as the base flake matrix with either a distribution of insoluble dopant particles or a dopant material that is completely soluble in the base flake matrix. The base flake matrix may be a polymer liquid crystal material, and the dopants generally have higher dielectric permittivity and/or conductivity than the electrically actuatable polymer base flake matrix. The dopant distribution within the base flake matrix may be either homogeneous or non-homogeneous. In the latter case, the non-homogeneous distribution of dopant provides a dielectric permittivity and/or conductivity gradient within the body of the flakes. The dopant can also be a carbon-containing material (either soluble or insoluble in the base flake matrix) that absorbs light so as to reduce the unpolarized scattered light component reflected from the flakes, thereby enhancing the effective intensity of circularly polarized light reflected from the flakes when the flakes are oriented into a light reflecting state. Electro-optic devices contain these doped flakes suspended in a host fluid can be addressed with an applied electric field, thus controlling the orientation of the flakes between a bright reflecting state and a non-reflecting dark state.

  11. The effect of interface oxygen content on magnetoelectric effect of epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaTiO{sub 3} bilayer

    SciTech Connect (OSTI)

    Tingxian, Li, E-mail: wxlltx@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455002 (China); Kuoshe, Li [National Engineering Research Central for Rare Earth Materials, General Research Institute for Nonferrous Metals, The Grirem Advanced materials Co. Ltd., Beijing 100088 (China)

    2014-01-28

    The epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaTiO{sub 3} (LSMO/BTO) bilayer films are grown on (001) oriented LaAlO{sub 3} substrate by pulsed laser deposition technique. The oxygen-rich interface is obtained through in-situ annealing process in oxygen, and the oxygen-deficient interface is obtained without the annealing process. The results show that the ferromagnetic properties of the LSMO film and the magnetoelectric effect (ME) of the bilayer films strongly correlate to the oxygen content at the interface of LSMO/BTO. The saturated magnetization and the ME voltage coefficient of the oxygen-rich bilayer film are higher than that of oxygen-deficient one. It suggests a more effective ME coupling at the LSMO/BTO interface, which are generated through not only the interface strain but also the spin polarized carriers.

  12. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01

    various transition or rare-earth metals provide a rich ?eldTransition Metal (Mn) and Rare Earth (Gd) Doped AmorphousTransition Metal (Mn) and Rare Earth (Gd) Doped Amorphous

  13. Tunable bilayer two-dimensional electron gas in LaAlO{sub 3}/SrTiO{sub 3} superlattices

    SciTech Connect (OSTI)

    Ma, H. J. Harsan E-mail: phyarian@nus.edu.sg; Annadi, A.; Zeng, S. W.; Ariando E-mail: phyarian@nus.edu.sg; Huang, Z.; Lü, W. M.; Wong, L. M.; Wang, S. J.; Venkatesan, T.

    2014-07-07

    We report magnetotransport properties of double heterointerfaces in LaAlO{sub 3}/SrTiO{sub 3}/LaAlO{sub 3}/SrTiO{sub 3}(001) (LAO/STO/LAO/STO). A strong nonlinearity in the Hall resistivity is found when the temperature is below 80?K. This effect is attributed to multichannel conduction of interfacial charges generated in double heterostructures of LAO/STO where two-dimensional electron gas (2DEG) is produced. The multichannel conduction is confirmed by back gating modulation of Hall effect. Our result suggests the possibility to achieve coupled bilayer 2DEG layers in LAO/STO superlattices.

  14. Influence of damping constant on inverse spin hall voltage of La{sub 0.7}Sr{sub 0.3}MnO{sub 3}(x)/platinum bilayers

    SciTech Connect (OSTI)

    Luo, G. Y. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Chang, C. R. [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Lin, J. G., E-mail: jglin@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-05-07

    Pure spin transport via spin pumping in the condition of ferromagnetic resonance can be transformed to charge current in the ferromagnetic/paramagnetic bilayer systems, based on inverse spin Hall effect (ISHE). Here, we explore La{sub 0.7}Sr{sub 0.3}MnO(x)/Pt(5.5?nm) [x?=?10 to 65 nm] bilayers to investigate the influence of damping constant on spin pumping efficiency. The results show that the ISHE voltage depend on the damping constant of magnetic moment, suggesting that the precession energy tansferred to lattice/electron of normal metal is a key parameter to control the magnitude of spin current.

  15. PUBLISHED ONLINE: 16 FEBRUARY 2015 | DOI: 10.1038/NMAT4203 Dysprosium-doped cadmium oxide as a gateway

    E-Print Network [OSTI]

    Curtarolo, Stefano

    and abinitio modelling, here we demonstrate an extreme peak of electron mobility in Dy-doped CdO plasmonic materials. In particular, extrinsic doping pins the CdO Fermi level above the conduction band. In this work, we present the conductive metal oxide (CMO) dysprosium-doped cadmium oxide (CdO:Dy) as the first

  16. Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal

    E-Print Network [OSTI]

    Suter, Dieter

    in a rare-earth-metal-ion-doped crystal Lars Rippe, Mattias Nilsson, and Stefan Kröll Department of Physics on optical interactions in rare-earth- metal-ion-doped crystals. The optical transition lines of the rare-earth-metal out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals

  17. Narrow band defect luminescence from Al-doped ZnO probed by scanning tunneling cathodoluminescence

    E-Print Network [OSTI]

    Russell, Kasey

    of the optical gap and Burstein-Moss shift in CdO thin films: A consequence of extended misuse of 2-versusNarrow band defect luminescence from Al-doped ZnO probed by scanning tunneling cathodoluminescence-like opto-electronic properties Appl. Phys. Lett. 99, 141917 (2011) Oxygen enhanced ferromagnetism in Cr-doped

  18. Band-gap tailoring of ZnO by means of heavy Al doping

    SciTech Connect (OSTI)

    Sernelius, B.E.; Berggren, K.; Jin, Z.; Hamberg, I.; Granqvist, C.G.

    1988-06-15

    Films of ZnO:Al were produced by weakly reactive dual-target magnetron sputtering. Optical band gaps, evaluated from spectrophotometric data, were widened in proportion to the Al doping. The widening could be quantitatively reconciled with an effective-mass model for n-doped semiconductors, provided the polar character of ZnO was accounted for.

  19. Stability of Graphene doping with MoO_3 and I_2

    E-Print Network [OSTI]

    D’Arsié, Lorenzo; Esconjauregui, Santiago; Weatherup, Robert; Guo, Yuzheng; Bhardwaj, Sunil; Centeno, Alba; Zurutuza, Amaia; Cepek, Cinzia; Robertson, John

    2014-09-08

    We dope graphene by evaporation of MoO_3 or by solution-deposition of I_2 and assess the doping stability for its use as transparent electrodes. Electrical measurements show that both dopants increase the graphene sheet conductivity and find that Mo...

  20. Improving thermostability of CrO{sub 2} thin films by doping with Sn

    SciTech Connect (OSTI)

    Ding, Yi; Wang, Ziyu; Liu, Shuo; Shi, Jing; Yin, Di; Yuan, Cheng; Lu, Zhihong; Xiong, Rui

    2014-09-01

    Chromium dioxide (CrO{sub 2}) is an ideal material for spin electronic devices since it has almost 100% spin polarization near Fermi level. However, it is thermally unstable and easily decomposes to Cr{sub 2}O{sub 3} even at room temperature. In this study, we try to improve the thermal stability of CrO{sub 2} thin films by doping with Sn whose oxide has the same structure as CrO{sub 2}. High quality epitaxial CrO{sub 2} and Sn-doped CrO{sub 2} films were grown on single crystalline TiO{sub 2} (100) substrates by chemical vapor deposition. Sn{sup 4+} ions were believed to be doped into CrO{sub 2} lattice and take the lattice positions of Cr{sup 4+}. The magnetic measurements show that Sn-doping leads to a decrease of magnetocrystalline anisotropy. The thermal stabilities of the films were evaluated by annealing the films at different temperatures. Sn-doped films can withstand a temperature up to 510?°C, significantly higher than what undoped films can do (lower than 435?°C), which suggests that Sn-doping indeed enhances the thermal stability of CrO{sub 2} films. Our study also indicates that Sn-doping may not change the essential half metallic properties of CrO{sub 2}. Therefore, Sn-doped CrO{sub 2} is expected to be very promising for applications in spintronic devices.

  1. Porous Doped Silicon Nanowires for Lithium Ion Battery Anode with Long Cycle Life

    E-Print Network [OSTI]

    Zhou, Chongwu

    for energy storage. Here, we report both experimental and theoretical studies of porous doped silicon in energy storage has stimulated significant interest in lithium ion battery research. The lithium ionPorous Doped Silicon Nanowires for Lithium Ion Battery Anode with Long Cycle Life Mingyuan Ge

  2. Photo-isomerization fronts in dye-doped nematic liquid crystals

    E-Print Network [OSTI]

    Gavilan, Marcel G. Clerc

    Photo-isomerization fronts in dye-doped nematic liquid crystals V. Odent,1, * M. G. Clerc,1 C study of the photo-isomerization dynamics in dye-doped nematic crystals is reported, which shows that and thus induc- ing a photo-controlled optical aperture. The optical intensity and temperature fields

  3. Irradiation of Dye-Doped Microspheres with a Strongly Focused Laser Beam

    E-Print Network [OSTI]

    Zare, Richard N.

    Irradiation of Dye-Doped Microspheres with a Strongly Focused Laser Beam Results in Alignment upon Received December 12, 2001 ABSTRACT The irradiation of dye-doped polystyrene microspheres with an argon ion trap (985 nm). This behavior is well described by a model in which the differently irradiated portions

  4. Reducing pulse distortion in fast-light pulse propagation through an erbium-doped

    E-Print Network [OSTI]

    Boyd, Robert W.

    Reducing pulse distortion in fast-light pulse propagation through an erbium-doped fiber amplifier, 2007 (Doc. ID 78405); published March 19, 2007 When a pulse superposed on a cw background propagates through an erbium-doped fiber amplifier with a negative group velocity, either pulse broadening or pulse

  5. Aalborg Universitet Comparative study of the break in process of post doped and solgel high temperature

    E-Print Network [OSTI]

    Berning, Torsten

    - brane (HTPEM) fuel cells based on phosphoric acid (PA) doped polybenzimidazole (PBI) is advantageous temperature proton exchange membrane fuel cells Vang, Jakob Rabjerg; Andreasen, Søren Juhl; Araya, Samuel in process of post doped and sol­gel high temperature proton exchange membrane fuel cells. International

  6. Electrical properties of Er-doped In0.53Ga0.47As

    E-Print Network [OSTI]

    Burke, Peter G.; Lu, Hong; Rudawski, Nicholas G.; Gossard, Arthur G.; Bahk, Je-Hyeong; Bowers, John E.

    2011-01-01

    03C117-3 Burke et al. : Electrical properties of Er-doped InElectrical properties of Er-doped In 0.53 Ga 0.47 As PeterBahk and John E. Bowers Electrical and Computer Engineering

  7. Hydrogen adsorption on Graphene and Nitrogen Doped Graphene Monolayers: A First Principles Study

    E-Print Network [OSTI]

    Petta, Jason

    Hydrogen adsorption on Graphene and Nitrogen Doped Graphene Monolayers: A First Principles Study Abstract This study examines the properties of graphene and nitrogen doped graphene by way of first principles spin-polarized Density Functional Theory calculations. Why graphene is so unique comes from

  8. Effect of Sn and Ca doping on the corrosion of Pb anodes in lead acid batteries

    E-Print Network [OSTI]

    Popov, Branko N.

    Effect of Sn and Ca doping on the corrosion of Pb anodes in lead acid batteries Dragan Slavkova corrosion rate as compared to pure lead anodes. In the present investigation, the dissolution of Pb reserved. Keywords: Corrosion; Pb anodes; Lead acid batteries; Doping tin; Calcium 1. Introduction

  9. Doped carbon-sulfur species nanocomposite cathode for Li--S batteries

    DOE Patents [OSTI]

    Wang, Donghai; Xu, Tianren; Song, Jiangxuan

    2015-12-29

    We report a heteroatom-doped carbon framework that acts both as conductive network and polysulfide immobilizer for lithium-sulfur cathodes. The doped carbon forms chemical bonding with elemental sulfur and/or sulfur compound. This can significantly inhibit the diffusion of lithium polysulfides in the electrolyte, leading to high capacity retention and high coulombic efficiency.

  10. Hafnium-doped tantalum oxide high-k gate dielectric films for future CMOS technology 

    E-Print Network [OSTI]

    Lu, Jiang

    2007-04-25

    A novel high-k gate dielectric material, i.e., hafnium-doped tantalum oxide (Hf-doped TaOx), has been studied for the application of the future generation metal-oxidesemiconductor field effect transistor (MOSFET). The film's electrical, chemical...

  11. Bose Glass of Quasiparticles in Doped Quantum Magnet Gregory S. Boebinger, National High Magnetic Field Laboratory

    E-Print Network [OSTI]

    Weston, Ken

    Bose Glass of Quasiparticles in Doped Quantum Magnet Gregory S. Boebinger, National High Magnetic. This BEC can localize in the presence of disorder caused by Br- doping to form a Bose Glass. The BEC-Bose Glass (BEC-BG) transition can be carefully controlled by magnetic field, allowing us to sensitively

  12. Optimization of charge transfer to the active channel in S-doped heterostructures

    E-Print Network [OSTI]

    Einevoll, Gaute T.

    properties of &modulation-doped semiconductor heterostructures with the aim of optimizing the active channel The principle of modulation doping' has been instru- mental in producing high-mobility semiconductor devices-band-gap material of a heterojunction away from the interface. The free carriers transfer to the lower-energy states

  13. Author's personal copy Prepration and photoluminescence properties of Ce doped lutetium silicate

    E-Print Network [OSTI]

    Cao, Guozhong

    Author's personal copy Prepration and photoluminescence properties of Ce doped lutetium silicate: Received 3 September 2010 Accepted 2 November 2010 Available online 12 November 2010 Keywords: Lutetium silicate Cerium Solegel Photoluminescence Lu2SiO5 a b s t r a c t Cerium doped lutetium silicate powders

  14. Implementation of three functional devices using Erbium-doped Fibers: An Advanced Photonics Lab

    E-Print Network [OSTI]

    Qian, Li

    , iv) transforming the EDFA into a tunable erbium doped fiber laser (EDFL). Through this series to construct light sources with the advantages of high output power and broad optical bandwidth [1]. The erbium education kits available in the market [5], we developed an experiment that use erbium-doped fiber

  15. PHYSICAL REVIEW B 86, 064302 (2012) Polarons in highly doped atomically thin graphitic materials

    E-Print Network [OSTI]

    Hague, Jim

    2012-01-01

    can be mechanically exfoliated, including SnS2, CdI2, and MoS2, but these have the chalcogenidePHYSICAL REVIEW B 86, 064302 (2012) Polarons in highly doped atomically thin graphitic materials J are computed for highly doped graphene-on-substrate and other atomically thin graphitic systems using

  16. Switching of emissivity and photoconductivity in highly doped Yb3+ and Lu2O3 ceramics

    E-Print Network [OSTI]

    Kouznetsov, Dmitrii

    Switching of emissivity and photoconductivity in highly doped Yb3+ :Y2O3 and Lu2O3 ceramics Jean bulk ceramics pumped at 940 nm wavelength. In contrast, when these materials are heated with a CO2- minescence properties of highly Yb3+ -doped 10% Lu2O3 and 15% and 20% Y2O3 polycrystalline ceramics14 pumped

  17. Generation of high peak power pulse using 2 stage erbium-doped fiber amplifier 

    E-Print Network [OSTI]

    Lee, Kyung-Woo

    2000-01-01

    This thesis presents the results obtained from generation of high repetition rate, high power output pulse using an erbium-doped fiber amplifier (EDFA). Two stage amplification was employed. The first stage setup used 980nm pump laser to pump erbium-doped...

  18. Enhanced Sintering of Yttrium-Doped Barium Zirconate by Addition of ZnO

    E-Print Network [OSTI]

    Haile, Sossina M.

    þ CeO2 (1) This reactivity causes severe degradation of the electrolyte and precludes applications properties of doped barium zirconate have been examined. With the use of zinc ox- ide as a sintering aid, BaZr of the alkaline earth perovskite family,15,17 it has been more recently recognized that doped BaZrO3, in fact

  19. Processing and Characterization of P-Type Doped Zinc Oxide Thin Films 

    E-Print Network [OSTI]

    Myers, Michelle Anne

    2013-03-18

    in the I-V curve, consistent with N-doped ZnO being p-type and forming a p-n junction. The turn-on voltage of the device was ?2.3 V under forward bias. The Ag-doped samples did not result in rectifying behavior as a result of conversion of the p-type layer...

  20. Chemical Expansion and Frozen-in Oxygen Vacancies in Pr-doped Ceria , S. R. Bishopa

    E-Print Network [OSTI]

    Yildiz, Bilge

    -7). Acceptor doped ceria is regarded as a promising candidate for several applications as solid oxide fuel cell temperatures and reduction/oxidation behavior. In the fuel cell application, CeO2-based solid electrolytes, USA Doped CeO2 is a promising candidate for solid oxide fuel cell electrolyte and electrode

  1. Radiative heat transfer at nanoscale mediated by surface plasmons for highly doped Emmanuel Rousseau

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Radiative heat transfer at nanoscale mediated by surface plasmons for highly doped silicon the role of surface plasmons for nanoscale radiative heat transfer between doped silicon surfaces. We derive a new accurate and closed-form expression of the radiative near- field heat transfer. We also

  2. The Electric and Optical Properties of Doped Small Molecular Organic Light-Emitting Devices

    SciTech Connect (OSTI)

    Kwang-Ohk Cheon

    2003-08-05

    Organic light-emitting devices (OLEDs) constitute a new and exciting emissive display technology. In general, the basic OLED structure consists of a stack of fluorescent organic layers sandwiched between a transparent conducting-anode and metallic cathode. When an appropriate bias is applied to the device, holes are injected from the anode and electrons from the cathode; some of the recombination events between the holes and electrons result in electroluminescence (EL). Until now, most of the efforts in developing OLEDs have focused on display applications, hence on devices within the visible range. However some organic devices have been developed for ultraviolet or infrared emission. Various aspects of the device physics of doped small molecular OLEDs were described and discussed. The doping layer thickness and concentration were varied systematically to study their effects on device performances, energy transfer, and turn-off dynamics. Low-energy-gap DCM2 guest molecules, in either {alpha}-NPD or DPVBi host layers, are optically efficient fluorophores but also generate deep carrier trap-sites. Since their traps reduce the carrier mobility, the current density decreases with increased doping concentration. At the same time, due to efficient energy transfer, the quantum efficiency of the devices is improved by light doping or thin doping thickness, in comparison with the undoped neat devices. However, heavy doping induces concentration quenching effects. Thus, the doping concentration and doping thickness may be optimized for best performance.

  3. Electrochemical sensing behaviour of Ni doped Fe{sub 3}O{sub 4} nanoparticles

    SciTech Connect (OSTI)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India); Vijayalakshmi, L. [Annai Veilankanni's College for Women (Arts and Science), Saidapet, Chennai 600015 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2014-01-28

    Ni doped Fe{sub 3}O{sub 4} nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe{sub 3}O{sub 4} nanoparticles. The optical property of Ni doped Fe{sub 3}O{sub 4} nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe{sub 3}O{sub 4} nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe{sub 3}O{sub 4} nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  4. Ferromagnetism at room temperature in Cr-doped anodic titanium dioxide nanotubes

    SciTech Connect (OSTI)

    Liao, Yulong E-mail: hwzhang@uestc.edu.cn; Zhang, Huaiwu E-mail: hwzhang@uestc.edu.cn; Li, Jie; Yu, Guoliang; Zhong, Zhiyong; Bai, Feiming; Jia, Lijun; Zhang, Shihong; Zhong, Peng

    2014-05-07

    This study reports the room-temperature ferromagnetism in Cr-doped TiO{sub 2} nanotubes (NTs) synthesized via the electrochemical method followed by a novel Cr-doping process. Scanning electron microscopy and transmission electron microscopy showed that the TiO{sub 2} NTs were highly ordered with length up to 26 ?m, outer diameter about 110 nm, and inner diameter about 100 nm. X-ray diffraction results indicated there were no magnetic contaminations of metallic Cr clusters or any other phases except anatase TiO{sub 2}. The Cr-doped TiO{sub 2} NTs were further annealed in oxygen, air and argon, and room-temperature ferromagnetism was observed in all Cr-doped samples. Moreover, saturation magnetizations and coercivities of the Cr-doped under various annealing atmosphere were further analyzed, and results indicate that oxygen content played a critical role in the room-temperature ferromagnetism.

  5. Effects of Cr doping on the magnetic properties of multiferroic YMnO{sub 3}

    SciTech Connect (OSTI)

    Han, Tai-Chun Wu, I-Chu; Hsu, Hsin-Kai

    2014-05-07

    We have synthesized a series of YMn{sub 1?x}Cr{sub x}O{sub 3} (0???x???0.1) samples and study the effect of Cr-doping on their magnetic properties. The magnetic characterization indicates that with increasing Cr-content up to 0.1, the antiferromagnetic (AFM) transition temperature increases from 73 to 89?K. Our experiment results also indicate that the Cr-doped samples exhibit the characteristics of spin-glass state at low temperature. Moreover, the magnetic hysteresis curves of the doped samples show a weak ferromagnetic (FM) behavior. It is found that the spin-glass state of the Cr-doped samples is due to the competition between AFM superexchange and FM double-exchange interaction, induced by the Cr doping.

  6. Investigation of structure, magnetic, and transport properties of Mn-doped SiC films

    SciTech Connect (OSTI)

    Sun Xianke [School of Material Science and Engineering, Tianjin University, Tianjin 300172 (China); Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin University of Technology, Tianjin 300384 (China); Guo Ruisong [School of Material Science and Engineering, Tianjin University, Tianjin 300172 (China); An Yukai [Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin University of Technology, Tianjin 300384 (China); School of Material Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Liu Jiwen [School of Material Science and Engineering, Tianjin University, Tianjin 300172 (China); Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin University of Technology, Tianjin 300384 (China); School of Material Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2013-07-15

    Mn-doped SiC films were fabricated by radio frequency magnetron sputtering technique. The structure, composition, and magnetic and transport properties of the films were investigated. The results show the films have the 3C-SiC crystal structure and the doped Mn atoms in the form of Mn{sup 2+} ions substitute for C sites in SiC lattice. All the films are ferromagnetic at 300 K, and the ferromagnetism in films arises from the doped Mn atoms and some extended defects. In addition, the saturation magnetization increases with the Mn-doped concentration increasing. The Mn doping does not change the semiconductor characteristics of the SiC films.

  7. Spin-dependent electron transport in zinc- and manganese-doped adenine molecules

    SciTech Connect (OSTI)

    Simchi, Hamidreza; Esmaeilzadeh, Mahdi Mazidabadi, Hossein

    2014-01-28

    The spin-dependent electron transport properties of zinc- and manganese-doped adenine molecules connected to zigzag graphene leads are studied in the zero bias regime using the non-equilibrium Green's function method. The conductance of the adenine molecule increased and became spin-dependent when a zinc or manganese atom was doped into the molecules. The effects of a transverse electric field on the spin-polarization of the transmitted electrons were investigated and the spin-polarization was controlled by changing the transverse electric field. Under the presence of a transverse electric field, both the zinc- and manganese-doped adenine molecules acted as spin-filters. The maximum spin-polarization of the manganese-doped adenine molecule was greater than the molecule doped with zinc.

  8. Variable temperature electrochemical strain microscopy of Sm-doped ceria

    SciTech Connect (OSTI)

    Jesse, Stephen; Morozovska, A. N.; Kalinin, Sergei V; Eliseev, E. A.; Yang, Nan; Doria, Sandra; Tebano, Antonello

    2013-01-01

    Variable temperature electrochemical strain microscopy has been used to study the electrochemical activity of Sm-doped ceria as a function of temperature and bias. The electrochemical strain microscopy hysteresis loops have been collected across the surface at different temperatures and the relative activity at different temperatures has been compared. The relaxation behavior of the signal at different temperatures has been also evaluated to relate kinetic process during bias induced electrochemical reactions with temperature and two different kinetic regimes have been identified. The strongly non-monotonic dependence of relaxation behavior on temperature is interpreted as evidence for water-mediated mechanisms.

  9. Bi-Se doped with Cu, p-type semiconductor

    DOE Patents [OSTI]

    Bhattacharya, Raghu Nath; Phok, Sovannary; Parilla, Philip Anthony

    2013-08-20

    A Bi--Se doped with Cu, p-type semiconductor, preferably used as an absorber material in a photovoltaic device. Preferably the semiconductor has at least 20 molar percent Cu. In a preferred embodiment, the semiconductor comprises at least 28 molar percent of Cu. In one embodiment, the semiconductor comprises a molar percentage of Cu and Bi whereby the molar percentage of Cu divided by the molar percentage of Bi is greater than 1.2. In a preferred embodiment, the semiconductor is manufactured as a thin film having a thickness less than 600 nm.

  10. Nitrogen-doped Graphene and Its Electrochemical Applications

    SciTech Connect (OSTI)

    Shao, Yuyan; Zhang, Sheng; Engelhard, Mark H.; Li, Guosheng; Shao, Guocheng; Wang, Yong; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

    2010-06-04

    Nitrogen-doped graphene (N-graphene) is obtained by exposing graphene to nitrogen plasma. N-graphene exhibits much higher electrocatalytic activity toward oxygen reduction and H2O2 reduction than graphene, and much higher durability and selectivity than the widely-used expensive Pt. The excellent electrochemical performance of N-graphene is attributed to nitrogen functional groups and the specific properties of graphene. This indicates that N-graphene is promising for applications in electrochemical energy devices (fuel cells, metal-air batteries) and biosensors.

  11. Spectral investigations of Sm{sup 3+}-doped oxyfluorosilicate glasses

    SciTech Connect (OSTI)

    Ramachari, D. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Rama Moorthy, L., E-mail: lrmphysics@yahoo.co.in [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Physics, Chadalawada Ramanamma Engineering College, Renigunta Road, Tirupati 517506 (India); Jayasankar, C.K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2013-09-01

    Graphical abstract: The figure shows the emission spectra of Sm{sup 3+} doped KNSZL glass for different concentrations. Among the four emission transitions {sup 4}G{sub 5/2} ? {sup 6}H{sub 5/2}, {sup 4}G{sub 5/2} ? {sup 6}H{sub 7/2}, {sup 4}G{sub 5/2} ? {sup 6}H{sub 9/2} and {sup 4}G{sub 5/2} ? {sup 6}H{sub 11/2}, the {sup 4}G{sub 5/2} ? {sup 6}H{sub 7/2} transition of KNSZLSm10 glass is more intense compared with all the transitions. The insert figure shows, the color coordinates (0.59, 0.41) of KNSZLSm10 glass is located on the perimeter of the chromaticity diagram at 592 nm which appears to be closest to the orange color. From these results the KNSZLSm10 glass could be useful for optical amplifiers, waveguides, telecommunications and orange LEDs. - Highlights: • From the DTA, the undoped KNSZL glass more precisely in fiberdrawing. • The XRD pattern confirmed the KNbO{sub 3} nanocrystallites of undoped KNSZL glass. • FTIR and Raman data of KNSZLSm10 glass revealed structural properties. • Judd–Ofelt analysis and decay measurements were carried out. • The optical gain parameter of the investigated glass is 18.13 × 10{sup ?25} cm{sup 2} s. - Abstract: Sm{sub 2}O{sub 3}-doped oxyfluorosilicate glasses were prepared by melt-quenching method. The differential thermal analysis and X-ray diffraction were carried out to investigate the glass transition temperature and structure of precursor glass. Infrared spectroscopy, Raman, optical absorption, photoluminescence and decay measurements were carried out for Sm{sup 3+}-doped oxyfluorosilicate glasses. From the absorption spectrum, the Judd–Ofelt intensity parameters have been evaluated to predict the radiative properties for the emission levels of Sm{sup 3+} ions. The lifetimes of {sup 4}G{sub 5/2} level are found to decrease from 1.17 to 0.93 ms due to the energy transfer, when the concentration of Sm{sup 3+} ions increases from 0.1 to 2.0 mol%. The optical gain parameter (18.13 × 10{sup ?25} cm{sup 2} s) of the investigated glass is found to be higher than the other Sm{sub 2}O{sub 3}-doped glass systems.

  12. Fabrication of solar cells with counter doping prevention

    DOE Patents [OSTI]

    Dennis, Timothy D; Li, Bo; Cousins, Peter John

    2013-02-19

    A solar cell fabrication process includes printing of dopant sources over a polysilicon layer over backside of a solar cell substrate. The dopant sources are cured to diffuse dopants from the dopant sources into the polysilicon layer to form diffusion regions, and to crosslink the dopant sources to make them resistant to a subsequently performed texturing process. To prevent counter doping, dopants from one of the dopant sources are prevented from outgassing and diffusing into the other dopant source. For example, phosphorus from an N-type dopant source is prevented from diffusing to a P-type dopant source comprising boron.

  13. Suppression of the spin pumping in Pd/Ni{sub 81}Fe{sub 19} bilayers with nano-oxide layer

    SciTech Connect (OSTI)

    Kim, Duck-Ho; Kim, Hong-Hyoun; You, Chun-Yeol

    2011-08-15

    We demonstrate that the spin pumping effect can be effectively suppressed with a nano-oxide layer. Spin pumping effect manifests itself by an enhancement of the Gilbert damping parameter in normal metal/ferromagnetic hetero-structures, while many spintronics devices prefer smaller damping parameter. Since the spin pumping effect is directly related with the spin dependent interface conductance, we can modify the spin pumping by altering the interface conductance with the nano-oxide layer. We prepared series of Pd/Ni{sub 81}Fe{sub 19} bilayers with different pausing time between Pd and Ni{sub 81}Fe{sub 19} depositions in order to control the interface conductance. The Gilbert damping parameters are determined from the line-width measurements in the ferromagnetic resonance spectra for each pausing time sample. They are 0.0490, 0.0296, 0.0278, and 0.0251 for 0, 6, 30, and 60 s pausing time, respectively. We find that the damping parameter of Pd/Ni{sub 81}Fe{sub 19} is almost recovered to one of the Cu/Ni{sub 81}Fe{sub 19} bilayer with 60 s pausing time, while the static magnetic properties are not noticeably changed.

  14. Effect of Antimicrobial Peptide on Dynamics of Phosphocholine Membrane: Role of Cholesterol and Physical State of Bilayer

    SciTech Connect (OSTI)

    Sharma, Veerendra K [ORNL; Mamontov, Eugene [ORNL; Anunciado, Divina B [ORNL; O'Neill, Hugh Michael [ORNL; Urban, Volker S [ORNL

    2015-01-01

    Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fall in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol % cholesterol. Thus, our measurements indicate that the destabilizing effect of the peptide melittin on membranes can be mitigated by the presence of cholesterol.

  15. Chloride, bromide and iodide scintillators with europium doping

    DOE Patents [OSTI]

    Zhuravleva, Mariya; Yang, Kan

    2014-08-26

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  16. Crystallization and doping of amorphous silicon on low temperature plastic

    DOE Patents [OSTI]

    Kaschmitter, J.L.; Truher, J.B.; Weiner, K.H.; Sigmon, T.W.

    1994-09-13

    A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate is disclosed. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900 C), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180 C for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180 C) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide. 5 figs.

  17. Crystallization and doping of amorphous silicon on low temperature plastic

    DOE Patents [OSTI]

    Kaschmitter, James L. (Pleasanton, CA); Truher, Joel B. (Palo Alto, CA); Weiner, Kurt H. (Campbell, CA); Sigmon, Thomas W. (Beaverton, OR)

    1994-01-01

    A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900.degree. C.), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180.degree. C. for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180.degree. C.) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide.

  18. Carbon doping of III-V compound semiconductors

    SciTech Connect (OSTI)

    Moll, A.J.

    1994-09-01

    Focus of the study is C acceptor doping of GaAs, since C diffusion coefficient is at least one order of magnitude lower than that of other common p-type dopants in GaAs. C ion implantation results in a concentration of free holes in the valence band < 10% of that of the implanted C atoms for doses > 10{sup 14}/cm{sup 2}. Rutherford backscattering, electrical measurements, Raman spectroscopy, and Fourier transform infrared spectroscopy were amonth the techniques used. Ga co-implantation increased the C activation in two steps: first, the additional radiation damage creates vacant As sites that the implanted C can occupy, and second, it maintains the stoichiometry of the implanted layer, reducing the number of compensating native defects. In InP, the behavior of C was different from that in GaAs. C acts as n-type dopant in the In site; however, its incorporation by implantation was difficult to control; experiments using P co-implants were inconsistent. The lattice position of inactive C in GaAs in implanted and epitaxial layers is discussed; evidence for formation of C precipitates in GaAs and InP was found. Correlation of the results with literature on C doping in III-V semiconductors led to a phenomenological description of C in III-V compounds (particularly GaAs): The behavior of C is controlled by the chemical nature of C and the instrinsic Fermi level stabilization energy of the material.

  19. Near-infrared free carrier absorption in heavily doped silicon

    SciTech Connect (OSTI)

    Baker-Finch, Simeon C.; McIntosh, Keith R.; Yan, Di; Fong, Kean Chern; Kho, Teng C.

    2014-08-14

    Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500?nm, and the range of dopant densities between ?10{sup 18} and 3?×?10{sup 20}?cm{sup ?3}. Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis.

  20. DOPING: a New Non-parametric Deprojection Scheme

    E-Print Network [OSTI]

    Dalia Chakrabarty; Laura Ferrarese

    2008-01-23

    We present a new non-parametric deprojection algorithm DOPING (Deprojection of Observed Photometry using and INverse Gambit), that is designed to extract the three dimensional luminosity density distribution $\\rho$, from the observed surface brightness profile of an astrophysical system such as a galaxy or a galaxy cluster, in a generalised geometry, while taking into account changes in the intrinsic shape of the system. The observable is the 2-D surface brightness distribution of the system. While the deprojection schemes presented hitherto have always worked within the limits of an assumed intrinsic geometry, in DOPING, geometry and inclination can be provided as inputs. The $\\rho$ that is most likely to project to the observed brightness data is sought; the maximisation of the likelihood is performed with the Metropolis algorithm. Unless the likelihood function is maximised, $\\rho$ is tweaked in shape and amplitude, while maintaining positivity, but otherwise the luminosity distribution is allowed to be completely free-form. Tests and applications of the algorithm are discussed.

  1. A series of Molybdenum-Copper bilayers were studied for use in 120mK superconducting transition edge sensors for spectrometer applications. The Transition temperature (TC) was tuned to the desired

    E-Print Network [OSTI]

    A series of Molybdenum-Copper bilayers were studied for use in 120mK superconducting transition temperature by adjusting the thickness of the normal copper layer and the superconducting molybdenum layer of a variable superconductor thickness 650Å dMo 1000Å. Material characterization techniques including X

  2. Structural and optical properties of chromium doped zinc oxide nanoparticles synthesized by sol-gel method

    SciTech Connect (OSTI)

    Naqvi, Syed Mohd. Adnan; Irshad, Kashif; Soleimani, Hassan E-mail: noorhana-yahya@petronas.com.my; Yahya, Noorhana E-mail: noorhana-yahya@petronas.com.my

    2014-10-24

    Nanosized Cr-doped ZnO nano particles were synthesized by facile sol-gel auto combustion method. The structural and optical properties of Cr-doped ZnO nanoparticles have been investigated by XRD and UV-Vis spectroscopy at room temperature for 0% to 8% concentration. X-ray diffraction analysis reveals that the Cr-doped ZnO crystallizes in a single phase polycrystalline nature with wurtzite lattice. With every % of doping, the peaks are shifting scarcely and doping of Cr is possible up to 7%. After that, the last peak vanishes, that signifies its structure is transmuted from 8% doping. The average crystallite size decreases with increase in Cr concentration (i.e. 28.9 nm for 0% to 25.8 nm for 8%). The UV-Vis spectra of the nanoparticles betoken an incrementation in the band gap energy from 3.401, 3.415, 3.431, 3.437,3.453, 3.514,3.521, 3.530 and 3.538 eV respectively, for 0,1, 2, 3, 4, 5, 6, 7 and 8 % doping concentration.

  3. Structural, optical and ethanol sensing properties of Cu-doped SnO{sub 2} nanowires

    SciTech Connect (OSTI)

    Johari, Anima Sharma, Manish; Johari, Anoopshi; Bhatnagar, M. C.

    2014-04-24

    In present work, one-dimensional nanostructure of Cu-doped Tin oxide (SnO{sub 2}) was synthesized by using thermal evaporation method in a tubular furnace under Nitrogen (N{sub 2}) ambience. The growth was carried out at atmospheric pressure. SEM and TEM images reveal the growth of wire-like nanostructures of Cu-doped SnO{sub 2} on Si substrate. The XRD analysis confirms that the synthesized SnO{sub 2} nanowires have tetragonal rutile structure with polycrystalline nature and X-ray diffraction pattern also showed that Cu gets incorporated into the SnO{sub 2} lattice. EDX spectra confirm the doping of Cu into SnO{sub 2} nanowires and atomic fraction of Cu in nanowires is ? 0.5 at%. The Vapor Liquid Solid (VLS) growth mechanism for Cu-doped SnO{sub 2} nanowires was also confirmed by EDX spectra. The optical properties of as grown Cu-doped SnO{sub 2} nanowires were studied by using UV-vis spectra which concludes the band gap of about 3.7 eV. As synthesized single Cu-doped SnO{sub 2} nanowire based gas sensor exhibit relatively good performance to ethanol gas. This sensing behaviour offers a suitable application of the Cu-doped SnO{sub 2} nanowire sensor for detection of ethanol gas.

  4. Influence of rare earth doping on thermoelectric properties of SrTiO{sub 3} ceramics

    SciTech Connect (OSTI)

    Liu, J. Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

    2013-12-14

    Thermoelectric properties of SrTiO{sub 3} ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO{sub 3} ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO{sub 3} ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr{sub 0.8}La{sub 0.18}Yb{sub 0.02}TiO{sub 3} ceramics were prepared, whose ZT value at 1?023?K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr{sub 0.8}La{sub 0.2}TiO{sub 3} (ZT?=?0.26)

  5. All-fiber Passively Q-switched Laser Based on Tm3+-doped Tellurite Fiber

    E-Print Network [OSTI]

    Kuan, Pei-Wen; Li, Kefeng; Zhang, Lei; Fan, Xiaokang; Hasan, Tawfique; Wang, Fengqiu; Hu, Lili

    2014-12-24

    the tellurite-based erbium-doped fiber and high numerical aperture (NA) silica fiber [20]. In practice, though commercial fusion splicers are available, the process of splicing two different fibers is complex. Due to this, ~2 µm tellurite fiber lasers have... monolithic single frequency 1.97 m Tm-doped fiber amplifier,” High Power Laser Sci. Eng., vol. 1, no 3-4, pp. 123-125, 2013. [4]. X. Wang, P. Zhou, X. Wang, H. Xiao, and Z. Liu, “Bursts with shape-alterable pulses in a compact Tm-doped fiber laser...

  6. Ge doped GaN with controllable high carrier concentration for plasmonic applications

    SciTech Connect (OSTI)

    Kirste, Ronny; Hoffmann, Marc P.; Sachet, Edward; Bobea, Milena; Bryan, Zachary; Bryan, Isaac; Maria, Jon-Paul; Collazo, Ramón; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)] [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States); Nenstiel, Christian; Hoffmann, Axel [Institut f?r Festkörperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)] [Institut f?r Festkörperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2013-12-09

    Controllable Ge doping in GaN is demonstrated for carrier concentrations of up to 2.4?×?10{sup 20} cm{sup ?3}. Low temperature luminescence spectra from the highly doped samples reveal band gap renormalization and band filling (Burstein-Moss shift) in addition to a sharp transition. Infrared ellipsometry spectra demonstrate the existence of electron plasma with an energy around 3500?cm{sup ?1} and a surface plasma with an energy around 2000?cm{sup ?1}. These findings open possibilities for the application of highly doped GaN for plasmonic devices.

  7. Structural studies and band gap tuning of Cr doped ZnO nanoparticles

    SciTech Connect (OSTI)

    Srinet, Gunjan Kumar, Ravindra Sajal, Vivek

    2014-04-24

    Structural and optical properties of Cr doped ZnO nanoparticles prepared by the thermal decomposition method are presented. X-ray diffraction studies confirmed the substitution of Cr on Zn sites without changing the wurtzite structure of ZnO. Modified form of W-H equations was used to calculate various physical parameters and their variation with Cr doping is discussed. Significant red shift was observed in band gap, i.e., a band gap tuning is achieved by Cr doping which could eventually be useful for optoelectronic applications.

  8. Defect Chemistry Study of Nitrogen Doped ZnO Thin Films

    SciTech Connect (OSTI)

    Miami University: Dr. Lei L. Kerr Wright State University: Dr. David C. Look and Dr. Zhaoqiang Fang

    2009-11-29

    Our team has investigated the defect chemistry of ZnO:N and developed a thermal evaporation (vapor-phase) method to synthesis p-type ZnO:N. Enhanced p-type conductivity of nitrogen doped ZnO via nano/micro structured rods and Zn-rich Co-doping process were studied. Also, an extended X-Ray absorption fine structure study of p-type nitrogen doped ZnO was conducted. Also reported are Hall-effect, photoluminescence, and DLTS studies.

  9. Thermophotovoltaic energy conversion system having a heavily doped n-type region

    DOE Patents [OSTI]

    DePoy, David M. (Clifton Park, NY); Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY)

    2000-01-01

    A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.

  10. Engineering high charge transfer n-doping of graphene electrodes and its application to organic electronics

    E-Print Network [OSTI]

    Sanders, Simon; Cabrero-Vilatela, Andrea; Kidambi, Piran R.; Alexander-Webber, Jack A.; Weijtens, Christ; Braeuninger, Philipp; Aria, Adrianus I.; Qasim, Malik M.; Wilkinson, Timothy D.; Robertson, John; Hofmann, Stephan; Meyer, Jens

    2015-07-06

    including organic photovoltaic cells and organic light emitting diodes (OLEDs).1–8 Most of these applications require low sheet resistances and detailed band engineering to optimize charge injection/extraction.1–8 Hence effective doping and the controlled... to applications but also as a model system to develop a detailed understanding of the n-doping mechanisms for organic electronics in general. Here, we focus on the n-type doping of monolayer graphene with an alkali metal compound i.e. cesium carbonate (Cs2CO3...

  11. Nonlocal study of the near field radiative heat transfer between two n-doped semiconductors

    E-Print Network [OSTI]

    Singer, F; Joulain, Karl

    2015-01-01

    We study in this work the near-field radiative heat transfer between two semi-infinite parallel planes of highly n-doped semiconductors. Using a nonlocal model of the dielectric permittivity, usually used for the case of metallic planes, we show that the radiative heat transfer coefficientsaturates as the separation distance is reduced for high doping concentration. These results replace the 1/d${}^2$ infinite divergence obtained in the local model case. Different features of the obtained results are shown to relate physically to the parameters of the materials, mainly the doping concentration and the plasmon frequency.

  12. Homogeneous versus spiral phases of hole-doped antiferromagnets: A systematic effective field theory investigation

    SciTech Connect (OSTI)

    Bruegger, C.; Kaempfer, F.; Wiese, U.-J.; Hofmann, C. P.; Pepe, M.

    2007-01-01

    Using the low-energy effective field theory for magnons and holes--the condensed matter analog of baryon chiral perturbation theory for pions and nucleons in QCD--we study different phases of doped antiferromagnets. We systematically investigate configurations of the staggered magnetization that provide a constant background field for doped holes. The most general configuration of this type is either constant itself or represents a spiral in the staggered magnetization. Depending on the values of the low-energy parameters, a homogeneous phase, a spiral phase, or an inhomogeneous phase is energetically favored. The reduction of the staggered magnetization upon doping is also investigated.

  13. Tensile-strain and doping enhanced direct bandgap optical transition of n{sup +} doped Ge/GeSi quantum wells

    SciTech Connect (OSTI)

    Fan, W. J.

    2013-11-14

    Band structures of tensile strained and n{sup +} doped Ge/GeSi quantum wells (QWs) are calculated by multiple-band k·p method. The energy dispersion curves of the ? and L conduction subbands are obtained. The effects of tensile strain and n{sup +} doping in Ge on direct bandgap optical gain and spontaneous radiative recombination rate spectra are investigated including the electron leakage from ? to L conduction subbands. Our results show that the optical gain and spontaneous radiative recombination rate can be significantly increased with the tensile strain, n-type doping concentration, and injection carrier density in the Ge QW. The free carrier absorption is calculated and cannot be ignored because of the heavily doped Ge. The pure TM mode polarized net optical gain up to 1153?cm{sup ?1} can be achieved for the Ge/Ge{sub 0.986}Si{sub 0.014} QW with tensile strain of 1.61% and n-type doping concentration of 30?×?10{sup 18}?cm{sup ?3}.

  14. Liquid crystal bilayer wall

    E-Print Network [OSTI]

    Aksay, Ilhan A.

    electron microscopy done on freeze fractured samples, as well as theoretical considerations. The pore tests show that the polymerization proceeds despite the mechanical failure. These findings suggest many to the shape of the reaction vessel. Because of these properties, we propose that the silica L3 could be used

  15. Pulsed energy synthesis and doping of silicon carbide

    DOE Patents [OSTI]

    Truher, J.B.; Kaschmitter, J.L.; Thompson, J.B.; Sigmon, T.W.

    1995-06-20

    A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate is disclosed, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27--730 C is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including HETEROJUNCTION-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

  16. Research and Development for a Gadolinium Doped Water Cherenkov Detector

    E-Print Network [OSTI]

    Andrew Renshaw

    2012-01-04

    The proposed introduction of a soluble gadolinium (Gd) compound into water Cherenkov detectors can result in a high efficiency for the detection of free neutrons capturing on the Gd. The delayed 8 MeV gamma cascades produced by these captures, in coincidence with a prompt positron signal, serve to uniquely identify electron antineutrinos interacting via inverse beta decay. Such coincidence detection can reduce backgrounds, allowing a large Gd-enhanced water Cherenkov detector to make the first observation of supernova relic neutrinos and high precision measurements of Japan's reactor antineutrino flux, while still allowing for all current physics studies to be continued. Now, a dedicated Gd test facility is operating in the Kamioka Mine. This new facility houses everything needed to successfully operate a Gd doped water Cherenkov detector. Successful running of this facility will demonstrate that adding Gd salt to SK is both safe for the detector and is capable of delivering the expected physics benefits.

  17. Structural and magnetic properties of chromium doped zinc ferrite

    SciTech Connect (OSTI)

    Sebastian, Rintu Mary; Thankachan, Smitha; Xavier, Sheena; Mohammed, E. M., E-mail: emmohammed2005@gmail.com [Research Department of Physics, Maharaja's College, Ernakulam, Kerala (India); Joseph, Shaji [Department of Physic, St. Albert's College, Ernakulam, Kerala (India)

    2014-01-28

    Zinc chromium ferrites with chemical formula ZnCr{sub x}Fe{sub 2?x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  18. Cr/sup 3 +/-doped colquiriite solid state laser material

    DOE Patents [OSTI]

    Payne, S.A.; Chase, L.L.; Newkirk, H.W.; Krupke, W.F.

    1988-03-31

    Chromium doped colquiriite, LiCaAlF/sub 6/:Cr/sup 3 +/, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr/sup 3 +/ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slope efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd/sup 3 +/ or Tm/sup 3 +/ for use in a multimegajoule single shot fusion research facility. 4 figs.

  19. Pulsed energy synthesis and doping of silicon carbide

    DOE Patents [OSTI]

    Truher, Joel B. (San Rafael, CA); Kaschmitter, James L. (Pleasanton, CA); Thompson, Jesse B. (Brentwood, CA); Sigmon, Thomas W. (Beaverton, OR)

    1995-01-01

    A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27.degree.-730.degree. C. is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including hetero-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

  20. Plasmonic Figures of Merit in a Doped Graphene Sheet | MIT-Harvard...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Plasmonic Figures of Merit in a Doped Graphene Sheet May 15, 2014 at 2pm36-428 Marco Polini NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore di Pisa MarcoPolini...

  1. Low-temperature electrical transport in B-doped ultrananocrystalline diamond film

    SciTech Connect (OSTI)

    Li, Lin; Zhao, Jing; Hu, Zhaosheng; Quan, Baogang; Li, Junjie Gu, Changzhi

    2014-05-05

    B-doped ultrananocrystalline diamond (UNCD) films are grown using hot-filament chemical vapor deposition method, and their electrical transport properties varying with temperature are investigated. When the B-doped concentration of UNCD film is low, a step-like increase feature of the resistance is observed with decreasing temperature, reflecting at least three temperature-modified electronic state densities at the Fermi level according to three-dimensional Mott's variable range hopping transport mechanism, which is very different from that of reported B-doped nanodiamond. With increasing B-doped concentration, a superconductive transformation occurs in the UNCD film and the highest transformation temperature of 5.3?K is observed, which is higher than that reported for superconducting nanodiamond films. In addition, the superconducting coherence length is about 0.63?nm, which breaks a reported theoretical and experimental prediction about ultra-nanoscale diamond's superconductivity.

  2. Engineering broadband and anisotropic photoluminescence emission from rare earth doped tellurite thin film photonic crystals

    E-Print Network [OSTI]

    Vanhoutte, Michiel

    Broadband and anisotropic light emission from rare-earth doped tellurite thin films is demonstrated using Er[superscript 3+]-TeO[subscript 2] photonic crystals (PhCs). By adjusting the PhC parameters, photoluminescent light ...

  3. Doped antiferromagnets in high dimension E. W. Carlson, S. A. Kivelson, and Z. Nussinov

    E-Print Network [OSTI]

    Carlson, Erica

    of a doped antiferromagnet on a d-dimensional hyper- cubic lattice are evaluated using a systematic expansion received 18 November 1997 The ground-state properties of the t-J model on a d-dimensional hypercubic

  4. Strong Asymmetrical Doping Properties of Spinel CoAl2O4

    SciTech Connect (OSTI)

    Feng, C. B.; Yin, W. J.; Nie, J. L.; Zu, X. T.; Huda, M. N.; Wei, S. H.; Al-Jassim, M. M.; Turner, J. A.; Yan, Y. F.

    2012-06-01

    Using first-principles density-functional theory, we have investigated the intrinsic and extrinsic doping properties of CoAl{sub 2}O{sub 4} by calculating the transition energies and formation energies of intrinsic and extrinsic defects. We find that CoAl{sub 2}O{sub 4} exhibits strong asymmetrical doping properties: Although excellent p-type conductivity can be achieved by Li or Na doping at O-rich growth condition, n-type conductivity cannot be achieved by any intrinsic or extrinsic dopants at any growth conditions. These asymmetrical doping properties are attributed to the formation of intrinsic defects, particularly Al{sub Co}, which has very low formation energy at all growth conditions. Our results suggest that for better use of CoAl{sub 2}O{sub 4}, the electronic devices should require CoAl{sub 2}O{sub 4} to exhibit p-type conductivity.

  5. Strain Determination in Electrochemically Doped Single-Walled Carbon Nanotubes via Raman Spectroscopy

    E-Print Network [OSTI]

    Nabben, Reinhard

    batteries,4 and actuators.5 Doping the nanotubes is an important method to influence their electronic) at 1600 cm-1 with a displace- ment pattern derived from the E2g bond-stretching mode of graphite

  6. Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-Tc Superconductor

    SciTech Connect (OSTI)

    Chen, Y.

    2010-05-03

    We report the discovery of a self-doped multi-layer high T{sub c} superconductor Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}F{sub 2} (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi surface(FS) sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a T{sub c} of 60K, possessing simultaneously both electron- and hole-doped FS sheets. Intriguingly, the FS sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic ({pi}/a, {pi}/a) scattering.

  7. Mode instability thresholds for Tm-doped fiber amplifiers pumped at 790 nm

    E-Print Network [OSTI]

    Smith, Arlee V

    2015-01-01

    We use a detailed numerical model of stimulated thermal Rayleigh scattering to compute mode instability thresholds in Tm$^{3+}$-doped fiber amplifiers. The fiber amplifies 2040 nm light using a 790 nm pump. The cross-relaxation process is strong, permitting power efficiencies of 60%. The predicted instability thresholds are compared with those in similar Yb$^{3+}$-doped fiber amplifiers with 976 nm pump and 1060 nm signal, and are found to be higher, even though the heat load is much higher in Tm-doped amplifiers. The higher threshold in the Tm-doped fiber is attributed to its longer signal wavelength, and to stronger gain saturation, due in part to cross-relaxation heating.

  8. Dielectric and electromechanical properties of barium and zirconium co-doped sodium bismuth titanate

    E-Print Network [OSTI]

    Sheets, Sossity A. (Sossity Amber), 1973-

    2000-01-01

    Compositional exploration was conducted within the alkaline bismuth titanate system by doping on the A- and B- sites with Ba?² and Zr??, respectively. Results on the phase, dielectric and electromechanical properties of ...

  9. JOURNAL OF MATERIALS SCIENCE 36 (2001) 77 86 Synthesis of yttria-doped strontium-zirconium

    E-Print Network [OSTI]

    Iglesia, Enrique

    2001-01-01

    JOURNAL OF MATERIALS SCIENCE 36 (2001) 77­ 86 Synthesis of yttria-doped strontium-zirconium oxide zirconium yttrium oxide, SrZr1-x Yx O3-x/2, forms crystallites with perovskite structure, which se

  10. Investigation of zinc oxide doped with metal impurities for use as thin film conductive phosphors 

    E-Print Network [OSTI]

    Evatt, Steven R.

    1994-01-01

    in which metal dopants were introduced in ZnO. This survey has revealed tungsten doped ZnO to be a previously unreported brilliant blue phosphor with high resistivity. Additional experiments indicated aluminum could be introduced in conjunction...

  11. Two dimensional electron transport in modulation-doped In{sub...

    Office of Scientific and Technical Information (OSTI)

    Two dimensional electron transport in modulation-doped Insub 0.53Gasub 0.47AsAlAssub 0.56Sbsub 0.44 ultrathin quantum wells Citation Details In-Document Search Title: Two...

  12. Systematic low-energy effective field theory for electron-doped antiferromagnets

    SciTech Connect (OSTI)

    Bruegger, C.; Kaempfer, F.; Moser, M.; Wiese, U.-J.; Hofmann, C. P.; Pepe, M.

    2007-06-01

    In contrast to hole-doped systems which have hole pockets centered at ({+-}({pi}/2a),{+-}({pi}/2a)), in lightly electron-doped antiferromagnets the charged quasiparticles reside in momentum space pockets centered at (({pi}/a),0) or (0,({pi}/a)). This has important consequences for the corresponding low-energy effective field theory of magnons and electrons which is constructed in this paper. In particular, in contrast to the hole-doped case, the magnon-mediated forces between two electrons depend on the total momentum P-vector of the pair. For P-vector=0, the one-magnon exchange potential between two electrons at distance r is proportional to 1/r{sup 4}, while in the hole case, it has a 1/r{sup 2} dependence. The effective theory predicts that spiral phases are absent in electron-doped antiferromagnets.

  13. Enhancement of Thermoelectric Properties by Modulation-Doping in Silicon Germanium Alloy Nanocomposites

    E-Print Network [OSTI]

    Yu, Bo

    Modulation-doping was theoretically proposed and experimentally proved to be effective in increasing the power factor of nanocomposites (Si[subscript 80]Ge[subscript 20])[subscript 70](Si[subscript 100]B[subscript 5])[subscript ...

  14. Electronic and magnetic properties of Fe and Mn doped two dimensional hexagonal germanium sheets

    SciTech Connect (OSTI)

    Soni, Himadri R. Jha, Prafulla K.

    2014-04-24

    Using first principles density functional theory calculations, the present paper reports systematic total energy calculations of the electronic properties such as density of states and magnetic moment of pristine and iron and manganese doped two dimensional hexagonal germanium sheets.

  15. Enhanced ripening behavior of Mg-doped CdSe quantum dots

    E-Print Network [OSTI]

    Kim, Tae-Geun

    In this study, CdO and Mg acetate were added into a mixture of paraffin oil and oleic acid (45:5) by 5 and 1 mEnhanced ripening behavior of Mg-doped CdSe quantum dots Yun-Mo Sung,a) Woo-Chul Kwak, and Woong November 2007; accepted 24 March 2008) Pure CdSe and Mg-doped CdSe nanocrystal quantum dots were

  16. Metal-doped single-walled carbon nanotubes and production thereof

    DOE Patents [OSTI]

    Dillon, Anne C.; Heben, Michael J.; Gennett, Thomas; Parilla, Philip A.

    2007-01-09

    Metal-doped single-walled carbon nanotubes and production thereof. The metal-doped single-walled carbon nanotubes may be produced according to one embodiment of the invention by combining single-walled carbon nanotube precursor material and metal in a solution, and mixing the solution to incorporate at least a portion of the metal with the single-walled carbon nanotube precursor material. Other embodiments may comprise sputter deposition, evaporation, and other mixing techniques.

  17. Supporting information for: Na-doped p-type ZnO , Faxian Xiu2

    E-Print Network [OSTI]

    Yang, Zheng

    S1 Supporting information for: Na-doped p-type ZnO microwires Wei Liu1* , Faxian Xiu2 , Ke Sun1 flow was switched to argon followed by cooling to room temperature. After the growth, high-density Zn distribution of the Na Doped ZnO microwire 1.3 EDX line scans spectra #12;S3 Figure S3 a) a typical TEM image

  18. Controlling ferromagnetism of (In,Fe)As semiconductors by electron doping

    SciTech Connect (OSTI)

    Dang Vu, Nguyen; Fukushima, Tetsuya; Katayama-Yoshida, Hiroshi [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Sato, Kazunori [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-02-21

    Based on experimental results, using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method and Monte Carlo simulation, we study the mechanism of ferromagnetic behavior of (In,Fe)As. We show that with doped Be atoms occupying in interstitial sites, chemical pair interactions between atoms and magnetic exchange interactions between Fe atoms change due to electron concentration. Therefore, by controlling the doping process, magnetic behavior of (In,Fe)As is controlled and ferromagnetism is observed in this semiconductor.

  19. Doping Cu{sub 2}O in Electrolyte Solution: Dopant Incorporation, Atomic Structures and Electrical Properties

    SciTech Connect (OSTI)

    Tao, Meng; Zhang, Qiming

    2013-11-24

    We have pursued a number of research activities between April 2010 and April 2011: ? A detailed study on n-type doping in Cu2O by Br; ? An analysis of natural resource limitations to terawatt-scale solar cells; ? Attempt to achieve a 1.4-eV direct band gap in Ni sulfides (NiSx); ? First-principles studies of doping in Cu2O and electronic structures of NiSx.

  20. p-Doping limit and donor compensation in CdTe polycrystalline thin film solar cells

    E-Print Network [OSTI]

    p-Doping limit and donor compensation in CdTe polycrystalline thin film solar cells Ken K. Chin n substitution of Cd CuCd 0=À #12; #12; play critical roles in p-doping of CdTe in CdS/CdTe thin film solar cells in Fig. 1. As for the CdTe polycrystalline thin film in a CdS/CdTe solar cell, it is still being debated

  1. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    SciTech Connect (OSTI)

    Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

    2007-02-15

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  2. Luminescent studies of fluorescent chromophore-doped silica aerogels for flat panel display applications

    SciTech Connect (OSTI)

    Glauser, S.A.C. [California Univ., Davis, CA (United States). Dept. of Applied Science; Lee, H.W.H. [Lawrence Livermore National Lab., CA (United States)

    1997-04-01

    The remarkable optical and electronic properties of doped and undoped silica aerogels establish their utility as unique, mulitfunctional host materials for fluorescent dyes and other luminescent materials for display and imaging applications. We present results on the photoluminescence, absorption, and photoluminescence excitation spectra of undoped silica aerogels and aerogels doped with Er{sup 3+}, rhodamine 6G (R6G), and fluorescein. 4 refs., 12 figs.

  3. Effect of co-doped SnO{sub 2} nanoparticles on photoluminescence of cu-doped potassium lithium borate glass

    SciTech Connect (OSTI)

    Namma, Haydar Aboud; Wagiran, H.; Hussin, R.; Ariwahjoedi, B. [Department of Physics, Universiti Teknologi Malaysia, Skudai 81310, Malaysia and Baghdad College of Economic Sciences University (Iraq); Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, 31750 Tronoh (Malaysia)

    2012-09-26

    The SnO{sub 2} co-doped lithium potassium borate glasses doped with 0.05, 0.10, 0.25 and 0.50 mol% of Cu were synthesized by the melt quenching technique. The SnO{sub 2} co-dope was added to the compounds in the amounts of 0.05, 0.10, and 0.20 mol%. The photoluminescent spectrum for different concentrations of copper was studied. It was observed that the intensity of blue emission (450, 490 nm) varies with concentration mol%. In addition, with different concentration of SnO{sub 2} to 0.10 mol% Cu, the influence of the luminescence has been observed to enhance intensity and shifted to blue and red (490, 535 nm) emissions.

  4. Vibration responses of h-BN sheet to charge doping and external strain

    SciTech Connect (OSTI)

    Yang, Wei; Yang, Yu; Zheng, Fawei [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)] [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Zhang, Ping, E-mail: zhang-ping@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China) [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Beijing Computational Science Research Center, Beijing 100084 (China)

    2013-12-07

    Based on density functional theory and density functional perturbation theory calculations, we systematically investigate the vibration responses of h-BN sheet to charge doping and external strains. It is found that under hole doping, the phonon frequencies of the ZO and TO branches at different wave vector q shift linearly with different slopes. Under electron doping, although the phonon frequencies shift irregularly, the shifting values are different at different phonon wave vectors. Interestingly, we find that external strain can restrain the irregular vibration responses of h-BN sheet to electron doping. The critical factor is revealed to be the relative position of the nearly free electron and boron p{sub z} states of h-BN sheet. Under external strains, the vibration responses of h-BN sheet are also found to be highly dependent on the phonon branches. Different vibration modes at different q points are revealed to be responsible for the vibration responses of h-BN sheet to charge doping and external strain. Our results point out a new way to detect the doping or strain status of h-BN sheet by measuring the vibration frequencies at different wave vector.

  5. Method of making self-aligned lightly-doped-drain structure for MOS transistors

    DOE Patents [OSTI]

    Weiner, Kurt H. (San Jose, CA); Carey, Paul G. (Mountain View, CA)

    2001-01-01

    A process for fabricating lightly-doped-drains (LDD) for short-channel metal oxide semiconductor (MOS) transistors. The process utilizes a pulsed laser process to incorporate the dopants, thus eliminating the prior oxide deposition and etching steps. During the process, the silicon in the source/drain region is melted by the laser energy. Impurities from the gas phase diffuse into the molten silicon to appropriately dope the source/drain regions. By controlling the energy of the laser, a lightly-doped-drain can be formed in one processing step. This is accomplished by first using a single high energy laser pulse to melt the silicon to a significant depth and thus the amount of dopants incorporated into the silicon is small. Furthermore, the dopants incorporated during this step diffuse to the edge of the MOS transistor gate structure. Next, many low energy laser pulses are used to heavily dope the source/drain silicon only in a very shallow region. Because of two-dimensional heat transfer at the MOS transistor gate edge, the low energy pulses are inset from the region initially doped by the high energy pulse. By computer control of the laser energy, the single high energy laser pulse and the subsequent low energy laser pulses are carried out in a single operational step to produce a self-aligned lightly-doped-drain-structure.

  6. Temperature Dependence of Aliovalent-vanadium Doping in LiFePO4 Cathodes

    SciTech Connect (OSTI)

    Harrison, Katharine L; Bridges, Craig A; Paranthaman, Mariappan Parans; Idrobo Tapia, Juan C; Manthiram, Arumugam; Goodenough, J. B.; Segre, C; Katsoudas, John; Maroni, V. A.

    2013-01-01

    Vanadium-doped olivine LiFePO4 cathode materials have been synthesized by a novel low-temperature microwave-assisted solvothermal (MW-ST) method at 300 oC. Based on chemical and powder neutron/X-ray diffraction analysis, the compositions of the synthesized materials were found to be LiFe1-3x/2Vx x/2PO4 (0 x 0.2) with the presence of a small number of lithium vacancies charge-compensated by V4+, not Fe3+, leading to an average oxidation state of ~ 3.2+ for vanadium. Heating the pristine 15 % V-doped sample in inert or reducing atmospheres led to a loss of vanadium from the olivine lattice with the concomitant formation of a Li3V2(PO4)3 impurity phase; after phase segregation, a partially V-doped olivine phase remained. For comparison, V-doped samples were also synthesized by conventional ball milling and heating, but only ~ 10 % V could be accommodated in the olivine lattice in agreement with previous studies. The higher degree of doping realized with the MW-ST samples demonstrates the temperature dependence of the aliovalent-vanadium doping in LiFePO4.

  7. Superparamagnetic behavior of Fe-doped SnO{sub 2} nanoparticles

    SciTech Connect (OSTI)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y.

    2014-02-20

    SnO{sub 2} is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO{sub 2} nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO{sub 2} nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO{sub 2}, were investigated. The particle size (1.8–16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO{sub 2} single-phase structure for samples annealed at 1073–1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO{sub 2} is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system.

  8. Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer

    DOE Patents [OSTI]

    Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Pittsburgh, PA)

    1995-01-01

    A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

  9. Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer

    DOE Patents [OSTI]

    Singh, P.; Ruka, R.J.

    1995-02-14

    A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO{sub 3} particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO{sub 3} particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr{sub 2}O{sub 3} on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO{sub 3} layer coated with CaO and Cr{sub 2}O{sub 3} surface deposit at from about 1,000 C to 1,200 C to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO{sub 3} layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power. 5 figs.

  10. Effect of doping on growth and field emission properties of spherical carbon nanotube tip placed over cylindrical surface

    SciTech Connect (OSTI)

    Santolia, Isha; Tewari, Aarti; Sharma, Suresh C.; Sharma, Rinku

    2014-06-15

    Theoretical investigations to study the effect of doping of hetero-atoms on the growth and field emission properties of Carbon Nanotubes (CNTs) tip placed over a cylindrical surface in complex plasma have been carried out. A theoretical model incorporating kinetics of plasma species such as electron, ions, and neutral atoms including doping elements like nitrogen (N) and boron (B) and energy balance of CNTs in a complex plasma has been developed. The effect of doping elements of N and B on the growth of CNTs, namely, the tip radius has been carried out for typical glow discharge plasma parameters. It is found that N and B as doping elements affect the radius of CNTs extensively. We obtain small radii of CNT doped with N and large radius of CNT doped with B. The field emission characteristics from CNTs have therefore been suggested on the basis of results obtained. Some of theoretical results are in compliance with the existing experimental observations.

  11. Observation of an electron band above the Fermi level in FeTe?.??Se?.?? from in-situ surface doping

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe?.??Se?.??. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe??xSe? compound.

  12. Effect of carrier doping on the formation and collapse of magnetic polarons in lightly hole-doped La1-xSrxCoO3

    SciTech Connect (OSTI)

    Podlesnyak, Andrey A; Ehlers, Georg; Frontzek, Matthias D; Sefat, A. S.; Furrer, Albert; Straessle, Thierry; Pomjakushina, Ekaterina; Conder, Kazimierz; Demmel, F.; Khomskii, D. I.

    2011-01-01

    We investigate the doping dependence of the nanoscale electronic and magnetic inhomogeneities in the hole-doping range 0.002 < x < 0.1 of cobalt based perovskites, La{sub 1-x}Sr{sub x}CoO{sub 3}. Using single-crystal inelastic neutron scattering and magnetization measurements we show that the lightly doped system exhibits magnetoelectronic phase separation in the form of spin-state polarons. Higher hole doping leads to a decay of spin-state polarons in favor of larger scale magnetic clusters, due to competing ferromagnetic correlations of Co{sup 3+} ions which are formed by neighboring polarons. The present data give evidence for two regimes of magnetoelectronic phase separation in this system: (i) x {approx}< 0.05, dominated by ferromagnetic intrapolaron interactions, and (ii) x {approx}> 0.05, dominated by Co{sup 3+}-Co{sup 3+} intracluster interactions. Our conclusions are in good agreement with a recently proposed model of the phase separation in cobalt perovskites.

  13. Study of Radioactive Impurities in Neutron Transmutation Doped Germanium

    E-Print Network [OSTI]

    S. Mathimalar; N. Dokania; V. Singh; V. Nanal; R. G. Pillay; A. Shrivastava; K. C. Jagadeesan; S. V. Thakare

    2014-11-27

    A program to develop low temperature (mK) sensors with neutron transmutation doped Ge for rare event studies with a cryogenic bolometer has been initiated. For this purpose, semiconductor grade Ge wafers are irradiated with thermal neutron flux from Dhruva reactor at BARC, Mumbai. Spectroscopic studies of irradiated samples have revealed that the environment of the capsule used for irradiating the sample leads to significant levels of $^{65}$Zn, $^{110}$Ag and $^{182}$Ta impurities, which can be reduced by chemical etching of approximately $\\sim50 \\mu$m thick surface layer. From measurements of the etched samples in the low background counting setup, activity due to trace impurities of $^{123}$Sb in bulk Ge is estimated to be $\\sim$ 1 Bq/gm after irradiation. These estimates indicate that in order to use the NTD Ge sensors for rare event studies, a cool down period of $\\sim$ 2 years would be necessary to reduce the radioactive background to $\\le$ 1 mBq/gm.

  14. Impurity-doped optical shock, detonation and damage location sensor

    DOE Patents [OSTI]

    Weiss, J.D.

    1995-02-07

    A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack. 8 figs.

  15. Method of preparing doped oxide catalysts for lean NOx exhaust

    DOE Patents [OSTI]

    Park, Paul W.

    2004-03-09

    The lean NOx catalyst includes a substrate, an oxide support material, preferably .gamma.-alumina deposited on the substrate and a metal or metal oxide promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium cerium, and vanadium, and oxides thereof, and any combinations thereof. The .gamma.-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between 80 and 350 m.sup.2 /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to about 0.2 weight percent. In a preferred embodiment the .gamma.-alumina is prepared by a sol-gel method, with the metal doping of the .gamma.-alumina preferably accomplished using an incipient wetness impregnation technique.

  16. Impurity-doped optical shock, detonation and damage location sensor

    DOE Patents [OSTI]

    Weiss, Jonathan D. (Albuquerque, NM)

    1995-01-01

    A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack.

  17. Optical emission from erbium-doped silica nanowires

    SciTech Connect (OSTI)

    Elliman, R. G.; Wilkinson, A. R.; Kim, T.-H.; Sekhar, P. K.; Bhansali, S.

    2008-05-15

    Infrared optical emission from erbium-doped silica nanowires is shown to have property characteristic of the material nanostructure and to provide the basis for the fabrication of integrated photonic devices and biosensors. Silica nanowires of approximately 150 nm diameter were grown on a silicon wafer by metal-induced growth using a thin (20 nm) sputter-deposited palladium layer as a catalyst. The resulting wires were then ion implanted with 110 keV ErO{sup -} ions and annealed at 900 deg. C to optically activate the erbium. These wires exhibited photoluminescence emission at 1.54 {mu}m, characteristic of the {sup 4}I{sub 15/2}-{sup 4}I{sub 13/2} transition in erbium; however, comparison to similarly implanted fused silica layers revealed stronger thermal quenching and longer luminescence lifetimes in the nanowire samples. The former is attributed to an increase in defect-induced quenching partly due to the large surface-volume ratio of the nanowires, while the latter is attributed to a reduction in the optical density of states associated with the nanostructure morphology. Details of this behavior are discussed together with the implications for potential device applications.

  18. DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE

    SciTech Connect (OSTI)

    Angela D. Lueking; Qixiu Li; John V. Badding; Dania Fonseca; Humerto Gutierrez; Apurba Sakti; Kofi Adu; Michael Schimmel

    2010-03-31

    Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

  19. Thermodynamic Analysis Of Pure And Impurity Doped Pentaerythritol Tetranitrate Crystals Grown At Room Temperature

    SciTech Connect (OSTI)

    Pitchimani, R; Zheng, W; Simon, S; Hope-Weeks, L; Burnham, A K; Weeks, B L

    2006-05-25

    Pentaerythritol tetranitrate (PETN) powders are used to initiate other explosives. During long-term storage, changes in powder properties can cause changes in the initiation performance. Changes in the morphology and surface area of aging powders are observed due to sublimation and growth of PETN crystals through coarsening mechanisms, (e.g. Ostwald ripening, sintering, etc.). In order to alleviate the sublimation of PETN crystals under service conditions, stabilization methods such as thermal cycling and doping with certain impurities during or after the crystallization of PETN have been proposed. In this report we present our work on the effect of impurities on the morphology and activation energy of the PETN crystals. The pure and impurity doped crystals of PETN were grown from supersaturated acetone solution by solvent evaporation technique at room temperature. The difference in the morphology of the impurity-doped PETN crystal compared to pure crystal was examined by optical microscopy. The changes in the activation energies and the evaporation rates are determined by thermogravimetric (TGA) analyses. Our activation energies of evaporation agree with earlier reported enthalpies of vaporization. The morphology and activation energy of PETN crystals doped with Ca, Na, and Fe cations are similar to that for pure PETN crystal, whereas the Zn-ion-doped PETN crystals have different morphology and decreased activation energy.

  20. D{sup 0} magnetism in Ca doped narrow carbon nanotubes: First principle chirality effect study

    SciTech Connect (OSTI)

    Hajiheidari, F.; Khoshnevisan, B.; Hashemifar, S. J.

    2014-06-21

    Curvature has always had crucial effects on the physical properties of narrow carbon nanotubes (CNTs) and here spin-polarized density functional calculations were employed to study electronic and magnetic properties of calcium-decorated narrow (5,5) and (9,0)CNTs with close diameters (?7?Å) and different chiralities. Our results showed that chirality had great impact on the electronic structure and magnetization of the doped CNTs. In addition, internally or externally doping of the calcium atoms was studied comparatively and although for the (9,0)CNT the internal doping was the most stable configuration, which involves a novel kind of spin-polarization originated from Ca-4s electrons, but for the (5,5)tube the external doping was the most stable one without any spin-polarization. On the other hand, calcium doping in the center of the (5,5)CNT was an endothermic process and led to the spin-polarization of unoccupied Ca-3d orbitals via direct exchange interaction between adjacent Ca atoms. In the considered systems, the existence of magnetization in the absence of any transition-metal elements was an example of valuable d{sup 0} magnetism title.

  1. Raman and XPS analyses of pristine and annealed N-doped double-walled carbon nanotubes

    E-Print Network [OSTI]

    Shi, Lei; Domanov, Oleg; Rohringer, Philip; Ayala, Paola; Pichler, Thomas

    2015-01-01

    N-doped single/multi-walled carbon nanotubes (CNTs) were studied for long time from synthesis to properties. However, the stability of N in the CNT lattice still needs further developments. In this work, to obtain more stable N-doped CNTs, concentric double-walled (DW) CNTs with more N were synthesized using benzylamine as C and N source. In order to test the stability of N-doped DWCNTs, high-temperature annealing in vacuum was performed. By XPS and Raman spectroscopic measurements, we found that the N-doped DWCNTs are still stable under 1500 $\\,^{\\circ}\\mathrm{C}$: the graphitic N does not change at all, the molecular N is partly removed, and the pyridinic N ratio greatly increases by more than two times. The reason could be that the N atoms from the surrounded N-contained materials combine into the CNT lattice during the annealing. Compared with the undoped DWCNTs, no Raman frequency shift was observed for the RBM, the G-band, and the G'-band of the N-doped DWCNTs.

  2. Magnetic properties of transition metal doped AlN nanosheet: First-principle studies

    SciTech Connect (OSTI)

    Shi, Changmin; Qin, Hongwei Zhang, Yongjia; Hu, Jifan; Ju, Lin

    2014-02-07

    We carry out our first-principles calculations within density functional theory to study the 3d transition metal (TM) doped AlN nanosheets. The calculated results indicate that a stoichiometric AlN nanosheet is graphene-like structure and nonmagnetic. The TM impurities can induce magnetic moments, localized mainly on the 3d TM atoms and neighboring N atoms. Our calculated results of TM-doped nanosheet systems indicate a strong interaction between 3d orbit of TM atom and the 2p orbit of N atoms. In addition, the Mn- and Ni-doped AlN nanosheet with half-metal characters seems to be good candidates for spintronic applications. When substituting two Al atoms, the relative energies of the states between ferromagnetic and antiferromagnetic coupling are investigated sufficiently. The exchange coupling of Co- and Ni-doped AlN nanosheets exhibits a transformation with different distances of two TM atoms and that of Cr-, Mn-, and Fe-doped AlN nanosheets is not changed.

  3. Nitrogen doping of chemical vapor deposition grown graphene on 4H-SiC (0001)

    SciTech Connect (OSTI)

    Urban, J. M.; Binder, J.; Wysmo?ek, A.; D?browski, P.; Strupi?ski, W.; Kopciuszy?ski, M.; Ja?ochowski, M.; Klusek, Z.

    2014-06-21

    We present optical, electrical, and structural properties of nitrogen-doped graphene grown on the Si face of 4H-SiC (0001) by chemical vapor deposition method using propane as the carbon precursor and N{sub 2} as the nitrogen source. The incorporation of nitrogen in the carbon lattice was confirmed by X-ray photoelectron spectroscopy. Angle-resolved photoemission spectroscopy shows carrier behavior characteristic for massless Dirac fermions and confirms the presence of a graphene monolayer in the investigated nitrogen-doped samples. The structural and electronic properties of the material were investigated by Raman spectroscopy. A systematical analysis of the graphene Raman spectra, including D, G, and 2D bands, was performed. In the case of nitrogen-doped samples, an electron concentration on the order of 5–10 × 10{sup 12}?cm{sup ?2} was estimated based upon Raman and Hall effect measurements and no clear dependence of the carrier concentration on nitrogen concentration used during growth was observed. This high electron concentration can be interpreted as both due to the presence of nitrogen in graphitic-like positions of the graphene lattice as well as to the interaction with the substrate. A greater intensity of the Raman D band and increased inhomogeneity, as well as decreased electron mobility, observed for nitrogen-doped samples, indicate the formation of defects and a modification of the growth process induced by nitrogen doping.

  4. Nitrogen-doped graphene as transparent counter electrode for efficient dye-sensitized solar cells

    SciTech Connect (OSTI)

    Wang, Guiqiang, E-mail: wgqiang123@163.com [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China)] [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China); Fang, Yanyan; Lin, Yuan [Institute of Chemistry, Chinese Academy of Science, Beijing 100080 (China)] [Institute of Chemistry, Chinese Academy of Science, Beijing 100080 (China); Xing, Wei; Zhuo, Shuping [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China)] [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ? NG sheets are prepared through a hydrothermal reduction of graphite oxide. ? The transparent NG counter electrodes of DSCs are fabricated at room temperature. ? Transparent NG electrode exhibits excellent catalytic activity for the reduction of I{sub 3}{sup ?}. ? The DSC with NG electrode achieves a comparable efficiency to that of the Pt-based cell. ? The efficiency of rear illumination is about 85% that of front illumination. -- Abstract: Nitrogen-doped graphene sheets are prepared through a hydrothermal reduction of graphite oxide in the presence of ammonia and applied to fabricate the transparent counter electrode of dye-sensitized solar cells. The atomic percentage of nitrogen in doped graphene sample is about 2.5%, and the nitrogen bonds display pyridine and pyrrole-like configurations. Cyclic voltammetry studies demonstrate a much higher electrocatalytic activity toward I{sup ?}/I{sub 3}{sup ?} redox reaction for nitrogen-doped graphene, as compared with pristine graphene. The dye-sensitized solar cell with this transparent nitrogen-doped graphene counter electrode shows conversion efficiencies of 6.12% and 5.23% corresponding to front-side and rear-side illumination, respectively. Meanwhile, the cell with a Pt counter electrode shows a conversion efficiency of 6.97% under the same experimental condition. These promising results highlight the potential application of nitrogen-doped graphene in cost-effective, transparent dye-sensitized solar cells.

  5. Improved gas sensing and dielectric properties of Fe doped hydroxyapatite thick films: Effect of molar concentrations

    SciTech Connect (OSTI)

    Mene, Ravindra U. [PDEA's, Annasaheb Waghire College of Science, Arts and Commerce, Otur 412409, M.S. (India); School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mahabole, Megha P. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mohite, K.C. [Haribhai. V. Desai College, Pune 411002, M.S. (India); Khairnar, Rajendra S., E-mail: rskhairnarsps@gmail.com [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India)

    2014-02-01

    Highlights: • We report improved gas sensing and dielectric characteristics of Fe ion exchanged HAp films. • Fe doped HAp film shows maximum gas response at relatively lower temperature. • Response and gas uptake capacity of sensors is improved for appropriate amount of Fe ions in HAp matrix. • Fe-HAp films exhibit remarkable improvement in dielectric properties compared to pure HAp. • Fe doped HAp films show significant improvement in gas sensing as well as in dielectric properties. - Abstract: In the present work Fe doped hydroxyapatite (Fe-HAp) thick films has been successfully utilized to improve the gas sensing as well as its dielectric properties. Initially, HAp nano powder is synthesized by chemical precipitation process and later on Fe ions are doped in HAp by ion exchange process. Structural and morphological modifications are observed by means of X-ray diffraction and scanning electron microscopy analysis. The sensing parameters such as operating temperature, response/recovery time and gas uptake capacity are experimentally determined. The Fe-HAp (0.05 M) film shows improved CO and CO{sub 2} gas sensing capacity at lower operating temperature compared to pure HAp. Moreover, variation of dielectric constant and dielectric loss for pure and Fe-HAp thick films are studied as a function of frequency in the range of 10 Hz–1 MHz. The study reveals that Fe doped HAp thick films improve the sensing and dielectric characteristics as compared to pure HAp.

  6. Formation of Carbon Nanostructures in Cobalt- and Nickel-Doped Carbon Aerogels

    SciTech Connect (OSTI)

    Fu, R; Baumann, T F; Cronin, S; Dresselhaus, G; Dresselhaus, M; Satcher, Jr., J H

    2004-11-09

    We have prepared carbon aerogels (CAs) doped with cobalt or nickel through sol-gel polymerization of formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by ion-exchange with M(NO{sub 3}){sub 2} (where M = Co{sup 2+} or Ni{sup 2+}), supercritical drying with liquid CO{sub 2} and carbonization at temperatures between 400 C and 1050 C under an N{sub 2} atmosphere. The nanostructures of these metal-doped carbon aerogels were characterized by elemental analysis, nitrogen adsorption, high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Metallic nickel and cobalt nanoparticles are generated during the carbonization process at about 400 C and 450 C, respectively, forming nanoparticles that are {approx}4 nm in diameter. The sizes and size dispersion of the metal particles increase with increasing carbonization temperatures for both materials. The carbon frameworks of the Ni- and Co-doped aerogels carbonized below 600 C mainly consist of interconnected carbon particles with a size of 15 to 30 nm. When the samples are pyrolyzed at 1050 C, the growth of graphitic nanoribbons with different curvatures is observed in the Ni and Co-doped carbon aerogel materials. The distance of graphite layers in the nanoribbons is about 0.38 nm. These metal-doped CAs retain the overall open cell structure of metal-free CAs, exhibiting high surface areas and pore diameters in the micro and mesoporic region.

  7. Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

    SciTech Connect (OSTI)

    Jin Yi; Zhu Yihua Yang Xiaoling; Li Chunzhong; Zhou Jinghong

    2007-01-15

    Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allows one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices. - Graphical abstract: Cerium-doped barium titanate inverted opal was synthesized from barium acetate acid contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a PS opal, which involves infiltration of precursors into the interstices of the PS opal template and removal of the PS opal by calcination.

  8. The thermoelectric properties of Ge/SiGe modulation doped superlattices A. Samarelli, L. Ferre Llin, S. Cecchi, J. Frigerio, T. Etzelstorfer et al.

    E-Print Network [OSTI]

    Hague, Jim

    The thermoelectric properties of Ge/SiGe modulation doped superlattices A. Samarelli, L. Ferre Llin thermoelectric properties of Ge/SiGe modulation doped superlattices A. Samarelli,1 L. Ferre Llin,1 S. Cecchi,2 J June 2013) The thermoelectric and physical properties of superlattices consisting of modulation doped

  9. Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells. de Bariloche, Argentina 3 ECN Solar Energy, High Tech Campus, Building 5, 5656 AE Eindhoven energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar

  10. AlTiN layer effect on mechanical properties of Ti-doped diamond-like carbon composite coatings

    E-Print Network [OSTI]

    Volinsky, Alex A.

    AlTiN layer effect on mechanical properties of Ti-doped diamond-like carbon composite coatings Adhesion Ti/Ti-doped diamond-like carbon (DLC) and Ti/AlTiN/Ti-DLC composite coatings were deposited on the properties of these composite coatings was investigated through microstructure and mechanical properties

  11. H.sub.2O doped WO.sub.3, ultra-fast, high-sensitivity hydrogen sensors

    DOE Patents [OSTI]

    Liu, Ping (Denver, CO); Tracy, C. Edwin (Golden, CO); Pitts, J. Roland (Lakewood, CO); Lee, Se-Hee (Lakewood, CO)

    2011-03-22

    An ultra-fast response, high sensitivity structure for optical detection of low concentrations of hydrogen gas, comprising: a substrate; a water-doped WO.sub.3 layer coated on the substrate; and a palladium layer coated on the water-doped WO.sub.3 layer.

  12. Hydrogen-doped cubic diamond and the crystal structure of n-diamond Bin Wen a,b,

    E-Print Network [OSTI]

    Melnik, Roderick

    Hydrogen-doped cubic diamond and the crystal structure of n-diamond Bin Wen a,b, , Roderick Melnik. In particular, hydrogen concen- tration dependent elastic constants and lattice parameters for the H-doped diamond have been analyzed. Our results indicate that when the hydrogen concentration is less than 19 at

  13. Hydrogen dissociation and diffusion on Ni-and Ti-doped Mg,,0001... M. Pozzo,1,2

    E-Print Network [OSTI]

    Alfè, Dario

    Hydrogen dissociation and diffusion on Ni- and Ti-doped Mg,,0001... surfaces M. Pozzo,1,2 D. Alfè,1 functional theory investigation of hydrogen dissociation and surface diffusion over a Ni-doped surface show that the energy barrier for hydrogen dissociation on the pure Mg 0001 surface is high, while

  14. Optical transitions and multiphonon Raman scattering of Cu doped ZnO and MgZnO ceramics

    E-Print Network [OSTI]

    McCluskey, Matthew

    Optical transitions and multiphonon Raman scattering of Cu doped ZnO and MgZnO ceramics Jesse Huso doped ZnO and MgZnO ceramics were created via a process of cold pressing and annealing, and their optical properties and phonon dynamics were studied. It was found that the ceramics exhibit infrared

  15. Infrared studies in free standing crystals: N,O-doped Xe and Ar W. G. Lawrence and V. A. Apkarian

    E-Print Network [OSTI]

    Apkarian, V. Ara

    Infrared studies in free standing crystals: N,O-doped Xe and Ar W. G. Lawrence and V. A. Apkarian 28 April 1992) Infrared studies in N20-doped free-standing crystals of Xe and Ar are reported. Nz annealing of the solids during growth, have become known as free- standing crystals (FSC). While

  16. Charge Transfer Induced Molecular Hole Doping into Thin Film of Metal-Organic-Frameworks

    E-Print Network [OSTI]

    Lee, Deok Yeon; Shrestha, Nabeen K; Boukhvalov, Danil W; Lee, Joong Kee; Han, Sung-Hwan

    2015-01-01

    Despite the highly porous nature with significantly large surface area, metal organic frameworks (MOFs) can be hardly used in electronic, and optoelectronic devices due to their extremely poor electrical conductivity. Therefore, the study of MOF thin films that require electron transport or conductivity in combination with the everlasting porosity is highly desirable. In the present work, thin films of Co3(NDC)3DMF4 MOFs with improved electronic conductivity are synthesized using layer-by-layer and doctor blade coating techniques followed by iodine doping. The as-prepared and doped films are characterized using FE-SEM, EDX, UV/Visible spectroscopy, XPS, current-voltage measurement, photoluminescence spectroscopy, cyclic voltammetry, and incident photon to current efficiency measurements. In addition, the electronic and semiconductor property of the MOF films are characterized using Hall Effect measurement, which reveals that in contrast to the insulator behavior of the as-prepared MOFs, the iodine doped MOFs ...

  17. Multi-wavelength Raman scattering of nanostructured Al-doped zinc oxide

    SciTech Connect (OSTI)

    Russo, V.; Ghidelli, M.; Gondoni, P. [Dipartimento di Energia and NEMAS, Center for Nanoengineered Materials and Surfaces, Politecnico di Milano, via Ponzio 34/3, I-20133 Milano (Italy); Casari, C. S.; Li Bassi, A. [Dipartimento di Energia and NEMAS, Center for Nanoengineered Materials and Surfaces, Politecnico di Milano, via Ponzio 34/3, I-20133 Milano (Italy); Center for Nano Science and Technology PoliMI, Istituto Italiano di Tecnologia, Via Pascoli 70/3, I-20133 Milano (Italy)

    2014-02-21

    In this work we present a detailed Raman scattering investigation of zinc oxide and aluminum-doped zinc oxide (AZO) films characterized by a variety of nanoscale structures and morphologies and synthesized by pulsed laser deposition under different oxygen pressure conditions. The comparison of Raman spectra for pure ZnO and AZO films with similar morphology at the nano/mesoscale allows to investigate the relation between Raman features (peak or band positions, width, relative intensity) and material properties such as local structural order, stoichiometry, and doping. Moreover Raman measurements with three different excitation lines (532, 457, and 325?nm) point out a strong correlation between vibrational and electronic properties. This observation confirms the relevance of a multi-wavelength Raman investigation to obtain a complete structural characterization of advanced doped oxide materials.

  18. Modification of phonon processes in nano-structured rare-earth-ion-doped crystals

    E-Print Network [OSTI]

    Lutz, Thomas; Thiel, Charles W; Cone, Rufus L; Barclay, Paul E; Tittel, Wolfgang

    2015-01-01

    Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable, or improve, persistent spectral hole-burning and optical coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and certain approaches to optical quantum memories. We specifically discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y$_2$SiO$_5$, a widely-used material in current quantum memory research.

  19. Origin of enhanced magnetization in rare earth doped multiferroic bismuth ferrite

    SciTech Connect (OSTI)

    Nayek, C.; Thirmal, Ch.; Murugavel, P., E-mail: muruga@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 36 (India); Tamilselvan, A.; Balakumar, S. [National Centre for Nanoscience and Nanotechnology, University of Madras, Chennai 25 (India)

    2014-02-21

    We report structural and magnetic properties of rare earth doped Bi{sub 0.95}R{sub 0.05} FeO{sub 3} (R?=?Y, Ho, and Er) submicron particles. Rare earth doping enhances the magnetization and the magnetization shows an increasing trend with decreasing dopant ionic radii. In contrast to the x-ray diffraction pattern, we have seen a strong evidence for the presence of rare earth iron garnets R{sub 3}Fe{sub 5}O{sub 12} in magnetization measured as a function of temperature, in selected area electron diffraction, and in Raman measurements. Our results emphasised the role of secondary phases in the magnetic property of rare earth doped BiFeO{sub 3} compounds along with the structural distortion favoring spin canting by increase in Dzyaloshinskii-Moriya exchange energy.

  20. Evaluation of the physi- and chemisorption of hydrogen in alkali (Na, Li) doped fullerenes

    SciTech Connect (OSTI)

    Ward, Patrick; Teprovich, Jospeph A.; Compton, Robert; Affholter, Kathleen A; Schwartz, Viviane; Veith, Gabriel M; Zidan, Ragiay

    2015-01-01

    Alkali doped fullerenes synthesized by two different solvent assisted mixing techniques are compared for their hydrogen uptake activity. In this study we investigated the interaction of hydrogen with alkali doped fullerenes via physisorption. In addition, we present the first mass spectrometric evidence for the formation of C60H60 via chemisorption. Hydrogen physisorption isotherms up to 1 atm at temperatures ranging from 77-303 K were measured demonstrating an increase in hydrogen uptake versus pure C60 and increased isosteric heats of adsorption for the lithium doped fullerene Li12C60. However, despite these improvements the low amount of physisorbed hydrogen at 1 atm and 77 K in these materials suggests that fullerenes do not possess enough accessible surface area to effectively store hydrogen due to their close packed crystalline nature.

  1. Nitrogen-doped mesoporous carbon for energy storage in vanadium redox flow batteries

    SciTech Connect (OSTI)

    Shao, Yuyan; Wang, Xiqing; Engelhard, Mark H.; Wang, Chong M.; Dai, Sheng; Liu, Jun; Yang, Zhenguo; Lin, Yuehe

    2010-03-22

    We demonstrate a novel electrode material?nitrogen-doped mesoporous carbon (NMC)?for vanadium redox flow batteries. Mesoporous carbon (MC) is prepared using a soft-template method and doped with nitrogen by heat-treating MC in NH3. NMC is characterized with X-ray photoelectron spectroscopy and transmission electron microscopy. The redox reaction of VO2+/VO2+ is characterized with cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic kinetics of the redox couple VO2+/VO2+ is significantly enhanced on NMC electrode compared with MC and graphite electrodes. The reversibility of the redox couple VO2+/VO2+ is greatly improved on NMC (0.61 for NMC vs. 0.34 for graphite). Nitrogen doping facilitates the electron transfer on the electrode/electrolyte interface for both oxidation and reduction processes. NMC is a promising electrode material for redox flow batteries.

  2. Doping of GaN{sub 1-x}As{sub x} with high As content

    SciTech Connect (OSTI)

    Levander, A.X.; Novikov, S.V.; Liliental-Weber, Z.; dos Reis, R.; Dubon, O.D.; Wu, J.; Foxon, C.T.; Yu, K.M.; Walukiewicz, W.

    2011-09-22

    Recent work has shown that GaN{sub 1-x}As{sub x} can be grown across the entire composition range by low temperature molecular beam epitaxy with intermediate compositions being amorphous, but control of the electrical properties through doping is critical for functionalizing this material. Here we report the bipolar doping of GaN{sub 1-x}As{sub x} with high As content to conductivities above 4 S/cm at room temperature using Mg or Te. The carrier type was confirmed by thermopower measurements. Doping requires an increase in Ga flux during growth resulting in a mixed phase material of polycrystalline GaAs:N embedded in amorphous GaN{sub 1-x}As{sub x}.

  3. Method for making defect-free zone by laser-annealing of doped silicon

    DOE Patents [OSTI]

    Narayan, Jagdish (Knoxville, TN); White, Clark W. (Oak Ridge, TN); Young, Rosa T. (Knoxville, TN)

    1980-01-01

    This invention is a method for improving the electrical properties of silicon semiconductor material. The method comprises irradiating a selected surface layer of the semiconductor material with high-power laser pulses characterized by a special combination of wavelength, energy level, and duration. The combination effects melting of the layer without degrading electrical properties, such as minority-carrier diffusion length. The method is applicable to improving the electrical properties of n- and p-type silicon which is to be doped to form an electrical junction therein. Another important application of the method is the virtually complete removal of doping-induced defects from ion-implanted or diffusion-doped silicon substrates.

  4. Laser-ablated active doping technique for visible spectroscopy measurements on Z.

    SciTech Connect (OSTI)

    Gomez, Matthew Robert

    2013-09-01

    Visible spectroscopy is a powerful diagnostic, allowing plasma parameters ranging from temperature and density to electric and magnetic fields to be measured. Spectroscopic dopants are commonly introduced to make these measurements. On Z, dopants are introduced passively (i.e. a salt deposited on a current-carrying surface); however, in some cases, passive doping can limit the times and locations at which measurements can be made. Active doping utilizes an auxiliary energy source to disperse the dopant independently from the rest of the experiment. The objective of this LDRD project was to explore laser ablation as a method of actively introducing spectroscopic dopants. Ideally, the laser energy would be delivered to the dopant via fiber optic, which would eliminate the need for time-intensive laser alignments in the Z chamber. Experiments conducted in a light lab to assess the feasibility of fibercoupled and open-beam laser-ablated doping are discussed.

  5. Thermodynamic and nonstoichiometric behavior of the lead-doped and lead-free Bi-2212 systems

    SciTech Connect (OSTI)

    Tetenbaum, M.; Hash, M.; Tani, B.S.; Luo, J.S.; Maroni, V.A.

    1997-02-01

    EMF measurements of oxygen fugacities as a function of stoichiometry were made on pb-doped and Pb-free superconducting ceramics at 700-815 C using oxygen titration. Equations of oxygen partial pressure vs composition and temperature were derived from the EMF measurements. Thermodynamic assessments of the partial molar quantities {Delta}{bar H}(O{sub 2}) and {Delta}{bar S}(O{sub 2}) for Pb-doped Bi- 2212 and Pb-free Bi-2212 indicate that the solid-state decomposition of these Bi cuprates at low oxygen partial pressure can be represented by the diphasic CuO-Cu{sub 2}O system. Comparison of these results with Pb-doped Bi-2223 in powder and silver sheath form is presented.

  6. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    E-Print Network [OSTI]

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  7. Mg doping of GaN grown by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions

    SciTech Connect (OSTI)

    Zhang Meng; Bhattacharya, Pallab; Guo Wei; Banerjee, Animesh [Department of Electrical Engineering and Computer Science, Solid-State Electronics Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

    2010-03-29

    Acceptor doping of GaN with Mg during plasma-assisted molecular beam epitaxy, under N-rich conditions and a relatively high growth temperature of 740 deg. C, was investigated. The p-doping level steadily increases with increasing Mg flux. The highest doping level achieved, determined from Hall measurements, is 2.1x10{sup 18} cm{sup -3}. The corresponding doping efficiency and hole mobility are approx4.9% and 3.7 cm{sup 2}/V s at room temperature. Cross-sectional transmission electron microscopy and photoluminescence measurements confirm good crystalline and optical quality of the Mg-doped layers. An InGaN/GaN quantum dot light emitting diode (lambda{sub peak}=529 nm) with p-GaN contact layers grown under N-rich condition exhibits a low series resistance of 9.8 OMEGA.

  8. The structural, electrical, and optical properties of hydrogenated chromium-doped CdO films

    SciTech Connect (OSTI)

    Dakhel, A.A.; Hamad, H.

    2013-12-15

    Cadmium oxide thin films doped with different amounts of chromium and annealed in hydrogen atmosphere have been grown on glass substrates by means of physical vapour deposition (PVD) method. The structural, electrical, and optical properties of the prepared Cr-doped CdO (CdO:Cr–H) films were systematically studied. The structural investigations show that the incorporated Cr ions mainly occupied locations in interstitial positions of CdO lattice. The bandgap engineer by Cr incorporation and hydrogenation were studied. The variations of the electrical parameters of CdO:Cr–H films with Cr incorporation and hydrogenation were investigated. It was established that among the investigated samples, the largest mobility and conductivity were measured with 1.5%:Cr–H film. Therefore, hydrogenated CdO:Cr films can be effectively used in different applications of near infrared-transparent-conducting-oxide (NIR-TCO). - Graphical abstract: Optoelectronic properties of synthesised chromium-doped CdO thin films. It was established that the largest mobility (53.4 cm{sup 2}/V.s) and conductivity (2136.8 S/cm) were measured in 1.5%:Cr–H doped CdO film. Therefore, such films can be effectively used in near infrared-transparent-conducting-oxide (NIR-TCO). - Highlights: • The properties of CdO films annealed in H{sub 2} gas were systematically studied. • Cr{sup 3+} ions most likely occupied interstitial locations in CdO lattice and as donors. • Improvement of conductivity parameters with Cr doping and H annealing. • Bandgap narrowing observed with Cd-doping.

  9. Selective area growth of Bernal bilayer epitaxial graphene on 4H-SiC (0001) substrate by electron-beam irradiation

    SciTech Connect (OSTI)

    Dharmaraj, P.; Jeganathan, K., E-mail: kjeganathan@yahoo.com [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Parthiban, S.; Kwon, J. Y. [School of Integrated Technology and Yonsei Institute of Convergence Technology, Yonsei University, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Gautam, S.; Chae, K. H. [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Asokan, K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2014-11-03

    We report selective area growth of large area homogeneous Bernal stacked bilayer epitaxial graphene (BLEG) on 4H-SiC (0001) substrate by electron-beam irradiation. Sublimation of Si occurs by energetic electron irradiations on SiC surface via breaking of Si–C bonds in the localized region, which allows the selective growth of graphene. Raman measurements ensure the formation of homogeneous BLEG with weak compressive strain of ?0.08%. The carrier mobility of large area BLEG is ?5100?cm{sup 2}?V{sup ?1}?s{sup ?1} with a sheet carrier density of 2.2?×?10{sup 13}?cm{sup ?2}. Current-voltage measurements reveal that BLEG on 4H-SiC forms a Schottky junction with an operation at mA level. Our study reveals that the barrier height at the Schottky junction is low (?0.58?eV) due to the Fermi-level pinning above the Dirac point.

  10. Dependence of inverse-spin Hall effect and spin-rectified voltage on tantalum thickness in Ta/CoFeB bilayer structure

    SciTech Connect (OSTI)

    Kim, Sang-Il; Seo, Min-Su; Park, Seung-Young; Kim, Dong-Jun; Park, Byong-Guk

    2015-01-19

    Ta-layer thickness (t{sub Ta}) dependence of the measured DC voltage V from the inverse-spin Hall effect (ISHE) in Ta/CoFeB bilayer structure is experimentally investigated using the ferromagnetic resonance in the TE{sub 011} resonant cavity. The ISHE signals excluding the spin-rectified effect (SRE) were separated from the fitted curve of V against t{sub Ta}. For t{sub Ta}????{sub Ta} (Ta-spin diffusion length?=?2.7?nm), the deviation in ISHE voltage V{sub ISH} between the experimental and theoretical values is significantly increased because of the large SRE contribution, which also results in a large deviation in the spin Hall angle ?{sub SH} (from 10% to 40%). However, when t{sub Ta} ? ?{sub Ta}, the V{sub ISH} values are consistent with theoretical values because the SRE terms become negligible, which subsequently improves the accuracy of the obtained ?{sub SH} within 4% deviation. The results will provide an outline for an accurate estimation of the ?{sub SH} for materials with small ? value, which would be useful for utilizing the spin Hall effect in a 3-terminal spintronic devices in which magnetization can be controlled by in-plane current.

  11. Study on the occurrence of spontaneously established perpendicular exchange bias in Co{sub 49}Pt{sub 51}/IrMn bilayers

    SciTech Connect (OSTI)

    Tsai, C. Y.; Lin, K. F. [Graduate Institute of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Saravanan, P. [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2014-05-07

    In this study, perpendicular exchange bias (PEB) effect in the as-grown Co{sub 49}Pt{sub 51}/IrMn bilayers was demonstrated at room temperature using single-layered Co{sub 49}Pt{sub 51} alloy thin film as ferromagnetic (FM) layer. Several unusual features were observed in this system, viz.,: (i) the PEB was spontaneously established without any external magnetic field treatments, (ii) single-shifted loops were obtained rather than double-shifted ones, and (iii) the spontaneous PEB effect was accompanied by a reduction in perpendicular coercivity, H{sub c?} from 1024 to 632?Oe. The results of x–ray diffraction revealed the formation of IrMn (111) texture. Training effect studies indicate that the PEB effect is stable in this system with less than 5% variation in PEB value within 15 repetitive scans. Significant reduction in the PEB effect was found for the CoPt/IrMn films either grown or subjected to post-annealing under external magnetic field (H{sub ind}). The thickness dependence of PEB effect with respect to the FM and antiferromagnetic layers were also investigated and a largest PEB value of 533?Oe was obtained for the sample grown with 3-nm thick CoPt and 10-nm thick IrMn layers. The results of present study thus establish an opportunity to realize PEB effect in the absence of external field during fabrication.

  12. Very fast doped LaBr.sub.3 scintillators and time-of-flight PET

    DOE Patents [OSTI]

    Shah, Kanai S.

    2006-10-31

    The present invention concerns very fast scintillator materials capable of resolving the position of an annihilation event within a portion of a human body cross-section. In one embodiment, the scintillator material comprises LaBr.sub.3 doped with cerium. Particular attention is drawn to LaBr.sub.3 doped with a quantity of Ce that is chosen for improving the timing properties, in particular the rise time and resultant timing resolution of the scintillator, and locational capabilities of the scintillator.

  13. Properties of a new average power Nd-doped phosphate laser glass

    SciTech Connect (OSTI)

    Payne, S.A.; Marshall, C.D.; Bayramian, A.J.; Wilke, G.D.; Hayden, J.S.

    1995-03-09

    The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially-available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties and by direct thermally-induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime.

  14. Laser properties of an improved average-power Nd-doped phosphate glass

    SciTech Connect (OSTI)

    Payne, S.A.; Marshall, C.D.; Bayramian, A.J.

    1995-03-15

    The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially-available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties (expansion, conduction, fracture toughness, and Young`s modulus), and by direct thermally-induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime.

  15. Features of a priori heavy doping of the n-TiNiSn intermetallic semiconductor

    SciTech Connect (OSTI)

    Romaka, V. A.; Rogl, P.; Romaka, V. V.; Hlil, E. K.; Stadnyk, Yu. V.; Budgerak, S. M.

    2011-07-15

    The crystal structure, the distribution of electron density, and the energy, kinetic, and magnetic properties of the n-TiNiSn intermetallic semiconductor are investigated. It is shown that a priori doping of n-TiNiSn with donors originates from partial, up to 0.5 at %, redistribution of Ti and Ni atoms in crystallographic sites of Ti atoms. The correlation is established between the donor concentration, amplitude of modulation of the continuous energy bands, and degree of filling of low-scale fluctuation potential wells with charge carriers. The results obtained are discussed within the Shklovskii-Efros model of a heavily doped and compensated semiconductor.

  16. Fermi arcs vs. fermi pockets in electron-doped perovskite iridates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    He, Junfeng; Hafiz, H.; Mion, Thomas R.; Hogan, T.; Dhital, C.; Oak Ridge National Lab.; Chen, X.; Lin, Qisen; Hashimoto, M.; Lu, D. H.; et al

    2015-02-23

    We report on an angle resolved photoemission (ARPES) study of bulk electron-doped perovskite iridate, (Sr1-xLax)?Ir?O?. Fermi surface pockets are observed with a total electron count in keeping with that expected from La substitution. Depending on the energy and polarization of the incident photons, these pockets show up in the form of disconnected “Fermi arcs”, reminiscent of those reported recently in surface electron-doped Sr?IrO?. Our observed spectral variation is consistent with the coexistence of an electronic supermodulation with structural distortion in the system.

  17. Mid infrared optical properties of Ge/Si quantum dots with different doping level

    SciTech Connect (OSTI)

    Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E.; Shalygin, V. A.; Panevin, V. Yu.; Vinnichenko, M. Ya.; Tonkikh, A. A.; Danilov, S. N.

    2013-12-04

    Optical characterization of the Ge/Si quantum dots using equilibrium and photo-induced absorption spectroscopy in the mid-infrared spectral range was performed in this work. Equilibrium absorption spectra were measured in structures with various doping levels for different light polarizations. Photo-induced absorption spectra measured in undoped structure under interband optical excitation of non-equilibrium charge carriers demonstrate the same features as doped sample in equilibrium conditions. Hole energy spectrum was determined from the analysis of experimental data.

  18. Determination of Gap Solution and Critical Temperature in Doped Graphene Superconductivity

    E-Print Network [OSTI]

    Chenmei Xu; Yisong Yang

    2015-09-27

    It is shown that the gap solution and critical transition temperature are significantly enhanced by doping in a recently developed BCS formalism for graphene superconductivity in such a way that positive gap and transition temperature both occur in arbitrary pairing coupling as far as doping is present. The analytic construction of the BCS gap and transition temperature offers highly effective globally convergent iterative methods for the computation of these quantities. A series of numerical examples are presented as illustrations consolidating the analytic understanding achieved.

  19. Semiconductor quantum dots enhanced graphene/CdTe heterostructure solar cells by photo-induced doping

    E-Print Network [OSTI]

    Li, Xiaoqiang; Wang, Peng; Xu, Zhijuan; Zhong, Huikai; Wu, Zhiqian; Lin, Shisheng

    2015-01-01

    Photo-induced doping is employed into graphene based solar cell through designing of a novel type of solar cell based on graphene/CdTe Schottky heterostructure. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the performance of the graphene/CdTe solar cell is improved by about 50%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by resistance, photoluminescence and quantum efficiency measurements. This work demonstrates a general and feasible way of designing novel type of solar cells based on two dimensional materials/semiconductor heterostructures.

  20. Doping of TiO 2 Polymorphs for Altered Optical and Photocatalytic Properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nie, Xiliang; Zhuo, Shuping; Maeng, Gloria; Sohlberg, Karl

    2009-01-01

    This paper reviews recent investigations of the influence of dopants on the optical properties of TiO 2 polymorphs. The common undoped polymorphs of TiO 2 are discussed and compared. The results of recent doping efforts are tabulated, and discussed in the context of doping by elements of the same chemical group. Dopant effects on the band gap and photocatalytic activity are interpreted with reference to a simple qualitative picture of the TiO 2 electronic structure,more »which is supported with first-principles calculations. « less

  1. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth Doped Crystal

    E-Print Network [OSTI]

    Christopher O'Brien; Nikolai Lauk; Susanne Blum; Giovanna Morigi; Michael Fleischhauer

    2014-07-25

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of $\\pi$-pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare earth doped crystals, we make use of a special transfer protocol using staggered $\\pi$-pulses. We predict total transfer efficiencies on the order of 90%.

  2. Doping ofTiO2Polymorphs for Altered Optical and Photocatalytic Properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nie, Xiliang; Zhuo, Shuping; Maeng, Gloria; Sohlberg, Karl

    2009-01-01

    This paper reviews recent investigations of the influence of dopants on the optical properties ofTiO2polymorphs. The common undoped polymorphs ofTiO2are discussed and compared. The results of recent doping efforts are tabulated, and discussed in the context of doping by elements of the same chemical group. Dopant effects on the band gap and photocatalytic activity are interpreted with reference to a simple qualitative picture of theTiO2electronic structure, which is supported with first-principles calculations.

  3. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles

    E-Print Network [OSTI]

    Derom, S; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Francs, G Colas des

    2013-01-01

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) are achieved by tuning either the dipolar or quadrupolar particle resonance to the rare earth ions excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  4. Charge carrier transport and separation in pristine and nitrogen-doped graphene nanowiggle heterostructures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lherbier, Aurélien; Liang, Liangbo; Charlier, Jean -Christophe; Meunier, Vincent

    2015-09-03

    Electronic structure methods are combined into a multiscale framework to investigate the electronic transport properties of recently synthesized pristine and nitrogen-doped graphene nanowiggles and their heterojunctions deposited on a substrate. The real-space Kubo-Greenwood transport calculations reveal that charge carrier mobilities reach values up to 1,000 cm2 V–1 s–1 as long as the amount of substrate impurities is sufficiently low. Owing to their type-II band alignment, atomically precise heterostructures between pristine and N-doped graphene nanowiggles are predicted to be excellent candidates for charge carrier separation devices with potential in photoelectric and photocatalytic water splitting applications.

  5. Heat treatment effect on the physical properties of cobalt doped TiO{sub 2} sol–gel materials

    SciTech Connect (OSTI)

    Samet, L., E-mail: lolwasamet@gmail.com [Institut Préparatoires aux Etudes d'Ingénieurs d'El-Manar, Université Tunis El Manar, Campus Universitaire, 2092 El Manar (Tunisia); Laboratoire de Photovoltaique de Semi-conducteur et de Nanostructure, Centre de Recherches et des Technologies de l'Energie, Technopole borj cedria, Bp 95, hammamm lif 2050 (Tunisia); Ben Nasseur, J.; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteur et de Nanostructure, Centre de Recherches et des Technologies de l'Energie, Technopole borj cedria, Bp 95, hammamm lif 2050 (Tunisia); March, K.; Stephan, O. [Laboratoire de Physique des Solides, UMR 8502 CNRS - Université Paris-Sud, Bât 510, 91405 Orsay cedex (France)

    2013-11-15

    Cobalt doped and undoped TiO{sub 2} powders have been prepared by sol–gel technique and annealed at temperatures ranging from 400 °C to 1000 °C. The effects of annealing temperature on the structural, morphological and optical properties have been characterized by X-ray diffraction, transmission electron microscopy, electron energy-loss spectroscopy and diffuse reflectance spectroscopy. For all doped samples there is a general reduction of the band gap energy, in comparison with undoped samples prepared in the same conditions. More specifically, experimental results indicate that cobalt doping, occurring as Co{sup 2+} ion insertion into the TiO{sub 2} (Ti{sup 4+}) host lattice, inhibits the growth of the crystallites and delays the phase transformation from anatase to rutile. Moreover, at high temperature, a secondary phase (CoTiO{sub 3}) is found to coexist with highly crystalline rutile. These structural characteristics are discussed in relation with the observed general trends for the optical properties. - Highlights: • Cobalt doped and undoped TiO{sub 2} powders have been prepared by sol–gel route. • Doping makes the band gap narrower. • Doping delays the phase transformation from anatase to rutile. • Doping inhibits the growth of the crystallites. • At high annealing temperature a CoTiO{sub 3} phase coexists with highly crystalline rutile.

  6. On the structural and impedance characteristics of Li- doped PEO, using n-butyl lithium in hexane as dopant

    SciTech Connect (OSTI)

    Anand, P. B., E-mail: anandputhirath@gmail.com, E-mail: jayalekshmi@cusat.ac.in; Jayalekshmi, S., E-mail: anandputhirath@gmail.com, E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials Department of Physics Cochin University of Science and Technology Cochin 22, Kerala (India)

    2014-01-28

    Nowadays polymer based solid state electrolytes for applications in rechargeable battery systems are highly sought after materials, pursued extensively by various research groups worldwide. Numerous methods are discussed in literature to improve the fundamental properties like electrical conductivity, mechanical stability and interfacial stability of polymer based electrolytes. The application of these electrolytes in Li-ion cells is still in the amateur state, due to low ionic conductivity, low lithium transport number and the processing difficulties. The present work is an attempt to study the effects of Li doping on the structural and transport properties of the polymer electrolyte, poly-ethelene oxide (PEO) (Molecular weight: 200,000). Li doped PEO was obtained by treating PEO with n-Butyllithium in hexane for different doping concentrations. Structural characterization of the samples was done by XRD and FTIR techniques. Impedance measurements were carried out to estimate the ionic conductivity of Li doped PEO samples. It is seen that, the crystallinity of the doped PEO decreases on increasing the doping concentration. XRD and FTIR studies support this observation. It is inferred that, ionic conductivity of the sample is increasing on increasing the doping concentration since less crystallinity permits more ionic transport. Impedance measurements confirm the results quantitatively.

  7. Computational investigation of the phase stability and the electronic properties for Gd-doped HfO{sub 2}

    SciTech Connect (OSTI)

    Wang, L. G. [General Research Institute for Nonferrous Metals, Beijing 100088 (China); California Institute of Technology, Pasadena, California 91125 (United States); Xiong, Y.; Xiao, W.; Cheng, L.; Du, J.; Tu, H. [General Research Institute for Nonferrous Metals, Beijing 100088 (China); Walle, A. van de [Brown University, Providence, Rhode Island 02912 (United States); California Institute of Technology, Pasadena, California 91125 (United States)

    2014-05-19

    Rare earth doping is an important approach to improve the desired properties of high-k gate dielectric oxides. We have carried out a comprehensive theoretical investigation on the phase stability, band gap, formation of oxygen vacancies, and dielectric properties for the Gd-doped HfO{sub 2}. Our calculated results indicate that the tetragonal phase is more stable than the monoclinic phase when the Gd doping concentration is greater than 15.5%, which is in a good agreement with the experimental observations. The dopant's geometric effect is mainly responsible for the phase stability. The Gd doping enlarges the band gap of the material. The dielectric constant for the Gd-doped HfO{sub 2} is in the range of 20–30 that is suitable for high-k dielectric applications. The neutral oxygen vacancy formation energy is 3.2?eV lower in the doped material than in pure HfO{sub 2}. We explain the experimental observation on the decrease of photoluminescence intensities in the Gd-doped HfO{sub 2} according to forming the dopant-oxygen vacancy complexes.

  8. FP-LAPW investigation of electronic, magnetic, elastic and thermal properties of Fe-doped zirconium nitride

    SciTech Connect (OSTI)

    Sirajuddeen, M. Mohamed Sheik, E-mail: msheiksiraj@bsauniv.ac.in; Banu, I. B. Shameem [Department of Physics, B. S. Abdur Rahman University, Chennai-600 048 (India)

    2014-05-15

    Full Potential- Linear Augmented Plane Wave (FP-LAPW) method has been employed to study the electronic, magnetic, elastic and thermal properties of Fe-doped Zirconium nitride. In this work, Fe-atoms were doped into the super cell of ZrN in doping concentrations of 12.5%, 25% and 37.5% to replace Zr atoms. Electronic properties such as band structure and DOS were plotted and compared for the doped compounds. Charge density contours were plotted for all the doped compounds. The non-magnetic ZrN doped in different Fe concentrations were found to be ferromagnetic. Magnetic moments have been calculated and compared. Elastic properties have been studied and compared with electronic properties. Appearance of magnetic ordering and its influence with the elastic properties have been reported. Impact of 3d states of Fe in DOS plot on the elastic nature of the compounds has been highlighted. Thermal properties such as Debye temperature and molar heat capacities at low temperature have been determined. Debye temperature is found to decrease with higher doping concentrations. Molar heat capacities are found to increase with higher concentrations of Fe atoms.

  9. A comparative study of optical absorption and photocatalytic properties of nanocrystalline single-phase anatase and rutile TiO{sub 2} doped with transition metal cations

    SciTech Connect (OSTI)

    Kernazhitsky, L.; Shymanovska, V.; Gavrilko, T.; Naumov, V.; Kshnyakin, V.; Khalyavka, T.

    2013-02-15

    The effect of nanocrystalline TiO{sub 2} doping with transition metal cations (Cu{sup 2+}, Fe{sup 3+}, Co{sup 2+}, Cr{sup 3+}) on their optical absorption and photocatalytic properties was investigated. The obtained metal-doped TiO{sub 2} samples were characterized by X-ray diffraction, scanning electron microscopy, and UV-vis absorption spectroscopy. It is shown that doping effect on anatase (A) and rutile (R) properties is quite different, being much stronger and complicated on A than on R. Contrary to doped R, doped A revealed a significant red shift of the absorption edge along with the band gap narrowing. Photocatalytic activity of anatase increases upon doping in the order: Adoping in the series R>R/Co>R/Cu>R/Fe>R/Cr, indicating the inhibitory effect of impurity cations. This fact correlates with the decrease in the UV absorption of the doped rutile in the region of the Hg-lamp irradiation at 4.88 eV. - Graphical abstract: A red shift of the absorption edge of nanocrystalline single-phase anatase after doping with transition metal cations. Highlights: Black-Right-Pointing-Pointer Single-phase anatase and rutile powders surface-doped with transition metal cations. Black-Right-Pointing-Pointer Absorption edge and band gap of rutile do not change with surface doping. Black-Right-Pointing-Pointer Band gap of surface-doped anatase reduces being the lowest for A/Fe. Black-Right-Pointing-Pointer The surface-doping improves photocatalytic activity of anatase. Black-Right-Pointing-Pointer The surface-doping inhibits photocatalytic activity of rutile.

  10. Impact of degenerate n-doping on the optical absorption edge in transparent conducting cadmium oxide

    E-Print Network [OSTI]

    Schleife, André

    n-type or can be heavily doped. Transparent conductive cadmium oxide (CdO) thin films, for instance in the conduction bands of CdO can increase the conductivity up to values desired for technological applications, have been known at least since 1907 and, in that sense, CdO can be seen as a pioneering TCO.1 Pure bulk

  11. Infrared and photoluminescence spectroscopy of p-doped self-assembled Ge dots on Si

    E-Print Network [OSTI]

    Rokhinson, Leonid

    Infrared and photoluminescence spectroscopy of p-doped self-assembled Ge dots on Si L. P and photoluminescence PL spectroscopy of self-assembled Ge dots grown on Si 100 by molecular beam epitaxy. PL spectra show a transition from two- to three-dimensional growth as the Ge thickness exceeds 7 Å. The sum

  12. Study on the Pumping Wavelength Dependency of -band Fluoride based Thulium Doped Fiber Amplifiers

    E-Print Network [OSTI]

    Park, Namkyoo

    amplifiers competing/compromizing L- band EDFA's, Raman amplifiers (RA's) and other rare-earth doped fiber TDFFA [4][5], the complexity of the amplification dynamics from the number of involving energy levels such as tunable pumping sources make it very hard to predict the performance of TDFFA in detail. This lack

  13. Structure of K-doped polyacetylene and its variations with annealing, studied by neutron diffraction

    E-Print Network [OSTI]

    Boyer, Edmond

    complementary information to X-ray diffraction can be obtained with neutrons. In addition, neutron scatteringL-379 Structure of K-doped polyacetylene and its variations with annealing, studied by neutron~u le 9 janvier 1985, accepte le 21 fevrier 1985) Résumé. 2014 On a étudié par diffraction de neutrons

  14. Four-wave mixing, quantum control and compensating losses in doped negative-index photonic metamaterials

    E-Print Network [OSTI]

    Alexander K. Popov; Sergey A. Myslivets; Thomas F. George; Vladimir M. Shalaev

    2007-08-13

    The possibility of compensating absorption in negative-index metatamterials (NIMs) doped by resonant nonlinear-optical centers is shown. The role of quantum interference and extraordinary properties of four-wave parametric amplification of counter-propagating electromagnetic waves in NIMs are discussed.

  15. Electrical and gas sensing properties of self-aligned copper-doped zinc oxide nanoparticles

    SciTech Connect (OSTI)

    Sonawane, Yogesh S.; Kanade, K.G.; Kale, B.B. Aiyer, R.C.

    2008-10-02

    Electrical and gas sensing properties of nanocrystalline ZnO:Cu, having Cu X wt% (X = 0.0, 0.5, 1.0, and 1.5) in ZnO, in the form of pellet were investigated. Copper chloride and zinc acetate were used as precursors along with oxalic acid as a precipitating reagent in methanol. Material characterization was done by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and inductive coupled plasma with optical emission spectrometry (ICP-OES). FE-SEM showed the self-aligned Cu-doped ZnO nano-clusters with particles in the range of 40-45 nm. The doping of 0.5% of copper changes the electrical conductivity by an order of magnitude whereas the temperature coefficient of resistance (TCR) reduces with increase in copper wt% in ZnO. The material has shown an excellent sensitivity for the H{sub 2}, LPG and CO gases with limited temperature selectivity through the optimized operating temperature of 130, 190 and 220 deg. C for H{sub 2}, LPG and CO gases, respectively at 625 ppm gas concentration. The %SF was observed to be 1460 for H{sub 2} at 1% Cu doping whereas the 0.5% Cu doping offered %SF of 950 and 520 for CO and LPG, respectively. The response and recovery time was found to be 6 to 8 s and 16 s, respectively.

  16. Magnetic and structural properties of Zn doped MnV{sub 2}O{sub 4}

    SciTech Connect (OSTI)

    Shahi, Prashant; Shukla, K. K.; Singh, Rahul; Chatterjee, Sandip; Das, A.; Ghosh, A. K.; Nigam, A. K.

    2014-04-24

    The magnetization, Neutron diffraction and X-ray diffraction of Zn doped MnV{sub 2}O{sub 4} as a function of temperature have been measured. It has been observed, with increase of Zn the non-linear orientation of Mn spins with the V spins will decrease which effectively decrease the structural transition temperature more rapidly than Curie Temperature.

  17. Enhanced Magnetism of Fe3O4 Nanoparticles with Ga Doping

    E-Print Network [OSTI]

    Pool, V. L.

    2011-01-01

    Solids 658, 345 (2004). V. L. Pool, M. T. Klem, J. Holroyd,Rev. B 64, 214422 (2001). V. Pool, M. Klem, C. Jolley, E. A.with Ga doping V. L. Pool, 1,a) M. T. Klem, 2,3 C. L.

  18. A Comparative Study of Phosphoric Acid-doped m-PBI Membranes

    SciTech Connect (OSTI)

    Perry, Kelly A [ORNL] [ORNL; More, Karren Leslie [ORNL] [ORNL; Payzant, E Andrew [ORNL] [ORNL; Meisner, Roberta A [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL)] [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Sumpter, Bobby G [ORNL] [ORNL; Benicewicz, Brian [ORNL] [ORNL

    2014-01-01

    Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes with 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.

  19. Manganese-doped ZnO nanobelts for spintronics C. Ronning,a)

    E-Print Network [OSTI]

    Wang, Zhong L.

    Manganese-doped ZnO nanobelts for spintronics C. Ronning,a) P. X. Gao, Y. Ding, and Z. L. Wangb and luminescence. The produced high-quality ZnO:Mn nanobelts are potentially useful for spintronics. © 2004 of the promising materials for spintronics (spin electronics), a proposed technology that uses the electron spin

  20. Tuning magnetism of monolayer MoS{sub 2} by doping vacancy and applying strain

    SciTech Connect (OSTI)

    Zheng, Huiling; Yang, Baishun; Han, Ruilin; Du, Xiaobo; Yan, Yu; Wang, Dingdi

    2014-03-31

    In view of important role of inducing and manipulating the magnetism in two-dimensional materials for the development of low-dimensional spintronic devices, the influences of strain on electronic structure and magnetic properties of commonly observed vacancies doped monolayer MoS{sub 2} are investigated using first-principles calculations. It is shown that unstrained V{sub S}, V{sub S2}, and V{sub MoS3} doped monolayer MoS{sub 2} systems are nonmagnetic, while the ground state of unstrained V{sub MoS6} doped system is magnetic and the magnetic moment is contributed mainly by six Mo atoms around V{sub MoS6}. In particular, tensile strain can induce magnetic moments in V{sub S}, V{sub S2}, and V{sub MoS3} doped monolayer MoS{sub 2} due to the breaking of Mo–Mo metallic bonds around the vacancies, while the magnetization induced by V{sub MoS6} can be effectively manipulated by equibiaxial strain due to the change of Mo–Mo metallic bonds around V{sub MoS6} under strains.