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Sample records for metal nanoscale devices

  1. Metal-dielectric-metal plasmonic waveguide devices for manipulating light at the nanoscale Invited Paper

    Institute of Scientific and Technical Information of China (English)

    Georgios Veronis; Zongfu Yu; Sukru Ekin Kocabas; David A. B. Miller; Mark L. Brongersma; Shanhui Fan

    2009-01-01

    We review some of the recent advances in the development of subwavelength plasmonic devices for ma- nipulating light at the nanoscale, drawing examples from our own work in metal-dielectric-metal (MDM) plasmonic waveguide devices. We introduce bends, splitters, and mode converters for MDM waveguides with no additional loss. We also demonstrate that optical gain provides a mechanism for on/off switch- ing in MDM plasmonie waveguides. Highly efficient compact couplers between dielectric waveguides and MDM waveguides are also introduced.

  2. Nanoscale Plasmonic Devices Based on Metal-Dielectric-Metal Stub Resonators

    Directory of Open Access Journals (Sweden)

    Yin Huang

    2012-01-01

    Full Text Available We review some of the recent research activities on plasmonic devices based on metal-dielectric-metal (MDM stub resonators for manipulating light at the nanoscale. We first introduce slow-light subwavelength plasmonic waveguides based on plasmonic analogues of periodically loaded transmission lines and electromagnetically induced transparency. In both cases, the structures consist of a MDM waveguide side-coupled to periodic arrays of MDM stub resonators. We then introduce absorption switches consisting of a MDM plasmonic waveguide side-coupled to a MDM stub resonator filled with an active material.

  3. Transparent electrode of nanoscale metal film for optoelectronic devices

    Science.gov (United States)

    Lee, Illhwan; Lee, Jong-Lam

    2015-01-01

    This paper reviews the principles, impediments, and recent progress in the development of ultrathin flexible Ag electrodes for use in flexible optoelectronic devices. Thin Ag-based electrodes are promising candidates for next-generation flexible transparent electrodes. Thin Ag-based electrodes that have a microcavity structure show the best device performance, but have relatively low optical transmittance (OT) due to reflection and absorption of photons by the thin Ag; this trait causes problems such as spectral narrowing and change of emission color with viewing angle in white organic light-emitting diodes. Thinning the Ag electrode to overcome these problems. This ultrathin Ag electrode has a high OT, while providing comparable sheet resistance similar to indium tin oxide. As the OT of the electrode increases, the cavity is weakened, so the spectral width of the emission and the angular color stability are increased.

  4. Atomistic simulations of electrochemical metallization cells: mechanisms of ultra-fast resistance switching in nanoscale devices.

    Science.gov (United States)

    Onofrio, Nicolas; Guzman, David; Strachan, Alejandro

    2016-08-01

    We describe a new method that enables reactive molecular dynamics (MD) simulations of electrochemical processes and apply it to study electrochemical metallization cells (ECMs). The model, called EChemDID, extends the charge equilibration method to capture the effect of external electrochemical potential on partial atomic charges and describes its equilibration over connected metallic structures, on-the-fly, during the MD simulation. We use EChemDID to simulate resistance switching in nanoscale ECMs; these devices consist of an electroactive metal separated from an inactive electrode by an insulator and can be reversibly switched to a low-resistance state by the electrochemical formation of a conducting filament between electrodes. Our structures use Cu as the active electrode and SiO2 as the dielectric and have dimensions at the foreseen limit of scalability of the technology, with a dielectric thickness of approximately 1 nm. We explore the effect of device geometry on switching timescales and find that nanowires with an electroactive shell, where ions migrate towards a smaller inactive electrode core, result in faster switching than planar devices. We observe significant device-to-device variability in switching timescales and intermittent switching for these nanoscale devices. To characterize the evolution in the electronic structure of the dielectric as dissolved metallic ions switch the device, we perform density functional theory calculations on structures obtained from an EChemDID MD simulation. These results confirm the appearance of states around the Fermi energy as the metallic filament bridges the electrodes and show that the metallic ions and not defects in the dielectric contribute to the majority of those states.

  5. Spintronics in nanoscale devices

    CERN Document Server

    Hedin, Eric R

    2013-01-01

    By exploiting the novel properties of quantum dots and nanoscale Aharonov-Bohm rings together with the electronic and magnetic properties of various semiconductor materials and graphene, researchers have conducted numerous theoretical and computational modeling studies and experimental tests that show promising behavior for spintronics applications. Spin polarization and spin-filtering capabilities and the ability to manipulate the electron spin state through external magnetic or electric fields have demonstrated the promise of workable nanoscale devices for computing and memory applications.

  6. Pure carbon nanoscale devices: Nanotube heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Chico, L.; Crespi, V.H.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States)]|[Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

    1996-02-01

    Introduction of pentagon-heptagon pair defects into the hexagonal network of a single carbon nanotube can change the helicity of the tube and alter its electronic structure. Using a tight-binding method to calculate the electronic structure of such systems we show that they behave as nanoscale metal/semiconductor or semiconductor/semiconductor junctions. These junctions could be the building blocks of nanoscale electronic devices made entirely of carbon. {copyright} {ital 1996 The American Physical Society.}

  7. Nanoscale wicking methods and devices

    Science.gov (United States)

    Zhou, Jijie (Inventor); Bronikowski, Michael (Inventor); Noca, Flavio (Inventor); Sansom, Elijah B. (Inventor)

    2011-01-01

    A fluid transport method and fluid transport device are disclosed. Nanoscale fibers disposed in a patterned configuration allow transport of a fluid in absence of an external power source. The device may include two or more fluid transport components having different fluid transport efficiencies. The components may be separated by additional fluid transport components, to control fluid flow.

  8. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

    Directory of Open Access Journals (Sweden)

    Randy L. Vander Wal

    2009-09-01

    Full Text Available A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC, controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine activation energies for the catalyst-assisted systems.

  9. The growth and applications of silicides for nanoscale devices.

    Science.gov (United States)

    Lin, Yung-Chen; Chen, Yu; Huang, Yu

    2012-03-01

    Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at the nanoscale have indicated possible deviations from the bulk and the thin film system. Here we present a review of fabrication, growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction.

  10. Nanoscale Electronic Devices

    Science.gov (United States)

    Jing, Xiaoye

    Continuous downscaling in microelectronics has pushed conventional CMOS technology to its physical limits, while Moore's Law has correctly predicted the trend for decades, each step forward is accompanied with unprecedented technological difficulties and near-exponential increase in cost. At the same time, however, demands for low-power, low-cost and high-speed devices have never diminished, instead, even more stringent requirements have been imposed on device performances. It is therefore crucial to explore alternative materials and device architectures in order to alleviate the pressure caused by downscaling. To this end, we investigated two different approaches: (1) InSb nanowire based field effect transistors (NWFETs) and (2) single walled carbon nanotube (SWCNT) -- peptide nucleic acid (PNA) --SWCNT conjugate. Two types of InSb nanowires were synthesized by template-assisted electrochemistry and chemical vapor deposition (CVD) respectively. In both cases, NWFETs were fabricated by electron beam lithography (EBL) and crystallinity was confirmed by transmission electron microscopy (TEM) and selected area diffraction (SAD) patterns. For electrochemistry nanowire, ambipolar conduction was observed with strong p-type conduction, the effect of thermal annealing on the conductivity was analyzed, a NWFET model that took into consideration the underlapped region in top-gated NWFET was proposed. Hole mobility in the channel was calculated to be 292.84 cm2V-1s -1 with a density of 1.5x1017/cm3. For CVD nanowire, the diameter was below 40nm with an average of 20nm. Vapor-liquid-solid (VLS) process was speculated to be the mechanism responsible for nanowire growth. The efficient gate control was manifested by high ION/I OFF ratio which was on the order of 106 and a small inverse subthreshold slope (<200 mV/decade). Scale analysis was used to successfully account for disparities observed among a number of sample devices. N-type conduction was found in all NWFETs with

  11. Direct temperature mapping of nanoscale plasmonic devices.

    Science.gov (United States)

    Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

    2014-02-12

    Side by side with the great advantages of plasmonics in nanoscale light confinement, the inevitable ohmic loss results in significant joule heating in plasmonic devices. Therefore, understanding optical-induced heat generation and heat transport in integrated on-chip plasmonic devices is of major importance. Specifically, there is a need for in situ visualization of electromagnetic induced thermal energy distribution with high spatial resolution. This paper studies the heat distribution in silicon plasmonic nanotips. Light is coupled to the plasmonic nanotips from a silicon nanowaveguide that is integrated with the tip on chip. Heat is generated by light absorption in the metal surrounding the silicon nanotip. The steady-state thermal distribution is studied numerically and measured experimentally using the approach of scanning thermal microscopy. It is shown that following the nanoscale heat generation by a 10 mW light source within a silicon photonic waveguide the temperature in the region of the nanotip is increased by ∼ 15 °C compared with the ambient temperature. Furthermore, we also perform a numerical study of the dynamics of the heat transport. Given the nanoscale dimensions of the structure, significant heating is expected to occur within the time frame of picoseconds. The capability of measuring temperature distribution of plasmonic structures at the nanoscale is shown to be a powerful tool and may be used in future applications related to thermal plasmonic applications such as control heating of liquids, thermal photovoltaic, nanochemistry, medicine, heat-assisted magnetic memories, and nanolithography.

  12. Exploring Carbon Nanotubes for Nanoscale Devices

    Science.gov (United States)

    Han, Jie; Dai; Anantram; Jaffe; Saini, Subhash (Technical Monitor)

    1998-01-01

    Carbon nanotubes (CNTs) are shown to promise great opportunities in nanoelectronic devices and nanoelectromechanical systems (NEMS) because of their inherent nanoscale sizes, intrinsic electric conductivities, and seamless hexagonal network architectures. I present our collaborative work with Stanford on exploring CNTs for nanodevices in this talk. The electrical property measurements suggest that metallic tubes are quantum wires. Furthermore, two and three terminal CNT junctions have been observed experimentally. We have proposed and studied CNT-based molecular switches and logic devices for future digital electronics. We also have studied CNTs based NEMS inclusing gears, cantilevers, and scanning probe microscopy tips. We investigate both chemistry and physics based aspects of the CNT NEMS. Our results suggest that CNT have ideal stiffness, vibrational frequencies, Q-factors, geometry-dependent electric conductivities, and the highest chemical and mechanical stabilities for the NEMS. The use of CNT SPM tips for nanolithography is presented for demonstration of the advantages of the CNT NEMS.

  13. Nanoscale metal-organic materials.

    Science.gov (United States)

    Carné, Arnau; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2011-01-01

    Metal-organic materials are found to be a fascinating novel class of functional nanomaterials. The limitless combinations between inorganic and organic building blocks enable researchers to synthesize 0- and 1-D metal-organic discrete nanostructures with varied compositions, morphologies and sizes, fabricate 2-D metal-organic thin films and membranes, and even structure them on surfaces at the nanometre length scale. In this tutorial review, the synthetic methodologies for preparing these miniaturized materials as well as their potential properties and future applications are discussed. This review wants to offer a panoramic view of this embryonic class of nanoscale materials that will be of interest to a cross-section of researchers working in chemistry, physics, medicine, nanotechnology, materials chemistry, etc., in the next years.

  14. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing in Aerospace Applications

    Science.gov (United States)

    VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.; Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.

    2009-01-01

    A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine an activation energy for the catalyst-assisted systems.

  15. Temperature mapping of operating nanoscale devices by scanning probe thermometry

    Science.gov (United States)

    Menges, Fabian; Mensch, Philipp; Schmid, Heinz; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-03-01

    Imaging temperature fields at the nanoscale is a central challenge in various areas of science and technology. Nanoscopic hotspots, such as those observed in integrated circuits or plasmonic nanostructures, can be used to modify the local properties of matter, govern physical processes, activate chemical reactions and trigger biological mechanisms in living organisms. The development of high-resolution thermometry techniques is essential for understanding local thermal non-equilibrium processes during the operation of numerous nanoscale devices. Here we present a technique to map temperature fields using a scanning thermal microscope. Our method permits the elimination of tip-sample contact-related artefacts, a major hurdle that so far has limited the use of scanning probe microscopy for nanoscale thermometry. We map local Peltier effects at the metal-semiconductor contacts to an indium arsenide nanowire and self-heating of a metal interconnect with 7 mK and sub-10 nm spatial temperature resolution.

  16. Status and perspectives of nanoscale device modelling

    DEFF Research Database (Denmark)

    Macucci, M.; Lannaccone, G.; Greer, J.;

    2001-01-01

    and the future perspectives of nanoscale device modelling. The outcome of such a discussion is summarized in the present paper, outlining the major challenges for the future, such as the integration of nonequilibrium phenomena and of molecular scale properties. We believe that modelling has a growing importance...

  17. Investigation of Device Performance and Negative Bias Temperature Instability of Plasma Nitrided Oxide in Nanoscale p-Channel Metal-Oxide-Semiconductor Field-Effect Transistor's

    Science.gov (United States)

    Han, In-Shik; Ji, Hee-Hwan; Goo, Tae-Gyu; Yoo, Ook-Sang; Choi, Won-Ho; Na, Min-Ki; Kim, Yong-Goo; Park, Sung-Hyung; Lee, Heui-Seung; Kang, Young-Seok; Kim, Dae-Byung; Lee, Hi-Deok

    2008-04-01

    In this paper, we investigated the device performance and negative bias temperature instability (NBTI) degradation for thermally nitrided oxide (TNO) and plasma nitrided oxide (PNO) in nanoscale p-channel metal oxide semiconductor field effect transistor (PMOSFET). PNOs show the improvement of dielectric performance compared to TNO with no change of the device performance. PNOs also show the improvement of NBTI immunity than TNO at low temperature stress, whereas NBTI immunity of PNO with high N concentration can be worse than TNO at high temperature stress. Recovery effect of NBTI degradation of PNO is lower than that of TNO and it is increased as the N concentration is increased in PNO because the dissociated Si dangling bonds and generated positive oxide charges are repassivated and neutralized, respectively. Moreover, complete recovery of ΔVth is dominated by neutralization of positive oxide charges. Therefore, N contents at polycrystalline Si/SiO2 interface as well as N contents at Si/SiO2 interface can affect significantly on NBTI degradation and recovery effect.

  18. Self-forming nanoscale devices

    Directory of Open Access Journals (Sweden)

    Lars Samuelson

    2003-10-01

    The top-down approach limits the dimensions of devices to what is technically achievable using lithography. This is the means by which patterns can be drawn, either in stone as the Vikings did when they carved messages into granite, or into Si as the electronics industry does today to build integrated circuits. Lithographic techniques can create device features as narrow as 130 nm and the industry sees the road ahead pretty well drawn up for line-widths down to ∼50 nm. This continued progress does not come without a price; the cost of new fabs is growing extremely fast, at a pace that may limit continued progress, simply because devices and circuits become too expensive to be economically viable.

  19. Thermal stability of nanoscale metallic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, A.S., E-mail: sofia.ramos@dem.uc.pt [CEMUC, Departamento de Engenharia Mecânica, Universidade de Coimbra, 3030-788 Coimbra (Portugal); Cavaleiro, A.J.; Vieira, M.T. [CEMUC, Departamento de Engenharia Mecânica, Universidade de Coimbra, 3030-788 Coimbra (Portugal); Morgiel, J. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Cracow (Poland); Safran, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1121 Budapest (Hungary)

    2014-11-28

    Metallic nanolayered thin films/foils, in particular Ni/Al multilayers, have been used to promote joining. The objective of this work is to evaluate the thermal stability of nanoscale metallic multilayers with potential for joining applications. Multilayers thin films with low (Ti/Al and Ni/Ti), medium (Ni/Al) and high (Pd/Al) enthalpies of exothermic reaction were prepared by dual cathode magnetron sputtering. Their thermal stability was studied by: i) differential scanning calorimetry combined with X-ray diffraction (XRD), ii) in-situ XRD using cobalt radiation, and iii) in-situ transmission electron microscopy. It was possible to detect traces of intermetallic or amorphous phases in the as-deposited short period (bilayer thickness) multilayers, except for the Ti/Al films where no reaction products that might be formed during deposition were identified. For short periods (below 20 nm) the equilibrium phases are directly achieved upon annealing, whereas for higher periods intermediate trialuminide phases are present for Ti/Al and Ni/Al multilayers. The formation of B2-NiTi from Ni/Ti multilayers occurs without the formation of intermediate phases. On the contrary, for the Pd–Al system the formation of intermediate phases was never avoided. The viability of nanoscale multilayers as “filler” materials for joining macro or microparts/devices was demonstrated. - Highlights: • Me1 and Me2 (Me—metal) alternated nanolayers deposited by magnetron sputtering • Reactive Me1/Me2 multilayer thin films with nanometric modulation period • By heat treatment the films always evolve to the equilibrium intermetallic phase. • For some Me1–Me2 systems and periods, the formation of intermediate phases occurs. • Me1/Me2 multilayer thin films can be used as filler materials to enhance joining.

  20. Nanoscale device physics science and engineering fundamentals

    CERN Document Server

    Tiwari, Sandip

    2017-01-01

    Nanoscale devices are distinguishable from the larger microscale devices in their specific dependence on physical phenomena and effects that are central to their operation. The size change manifests itself through changes in importance of the phenomena and effects that become dominant and the changes in scale of underlying energetics and response. Examples of these include classical effects such as single electron effects, quantum effects such as the states accessible as well as their properties; ensemble effects ranging from consequences of the laws of numbers to changes in properties arising from different magnitudes of the inter-actions, and others. These interactions, with the limits placed on size, make not just electronic, but also magnetic, optical and mechanical behavior interesting, important and useful. Connecting these properties to the behavior of devices is the focus of this textbook. Description of the book series: This collection of four textbooks in the Electroscience series span the undergrad...

  1. Nanoscale chirality in metal and semiconductor nanoparticles.

    Science.gov (United States)

    Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

    2016-10-18

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

  2. Properties of nanoscale metal hydrides.

    Science.gov (United States)

    Fichtner, Maximilian

    2009-05-20

    Nanoscale hydride particles may exhibit chemical stabilities which differ from those of a macroscopic system. The stabilities are mainly influenced by a surface energy term which contains size-dependent values of the surface tension, the molar volume and an additional term which takes into account a potential reduction of the excess surface energy. Thus, the equilibrium of a nanoparticular hydride system may be shifted to the hydrogenated or to the dehydrogenated side, depending on the size and on the prefix of the surface energy term of the hydrogenated and dehydrogenated material. Additional complexity appears when solid-state reactions of complex hydrides are considered and phase segregation has to be taken into account. In such a case the reversibility of complex hydrides may be reduced if the nanoparticles are free standing on a surface. However, it may be enhanced if the system is enclosed by a nanoscale void which prevents the reaction partners on the dehydrogenated side from diffusing away from each other. Moreover, the generally enhanced diffusivity in nanocrystalline systems may lower the kinetic barriers for the material's transformation and, thus, facilitate hydrogen absorption and desorption.

  3. Gate stack technology for nanoscale devices

    Directory of Open Access Journals (Sweden)

    Byoung Hun Lee

    2006-06-01

    Full Text Available Scaling of the gate stack has been a key to enhancing the performance of complementary metal-oxide-semiconductor (CMOS field-effect transistors (FETs of past technology generations. Because the rate of gate stack scaling has diminished in recent years, the motivation for alternative gate stacks or novel device structures has increased considerably. Intense research during the last decade has led to the development of high dielectric constant (k gate stacks that match the performance of conventional SiO2-based gate dielectrics. However, many challenges remain before alternative gate stacks can be introduced into mainstream technology. We review the current status of and challenges in gate stack research for planar CMOS devices and alternative device technologies to provide insights for future research.

  4. Transparent subdiffraction optics: nanoscale light confinement without metal

    CERN Document Server

    Jahani, Saman

    2014-01-01

    The integration of nanoscale electronics with conventional optical devices is restricted by the diffraction limit of light. Metals can confine light at the subwavelength scales needed, but they are lossy, while dielectric materials do not confine evanescent waves outside a waveguide or resonator, leading to cross talk between components. We show that light can be confined below the diffraction limit using completely transparent artificial media. Our approach relies on controlling the optical momentum of evanescent waves, an important electromagnetic property overlooked in photonic devices. For practical applications, we propose a class of waveguides using this approach that outperforms the cross talk performance by 1 order of magnitude as compared to any existing photonic structure. Our work overcomes a critical stumbling block for nanophotonics by completely averting the use of metals and can impact electromagnetic devices from the visible to microwave frequency ranges.

  5. Device Physics of Nanoscale Interdigitated Solar Cells (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, W.; Levi, D.

    2008-05-01

    Nanoscale interdigitated solar cell device architectures are being investigated for organic and inorganic solar cell devices. Due to the inherent complexity of these device designs quantitative modeling is needed to understand the device physics. Theoretical concepts have been proposed that nanodomains of different phases may form in polycrystalline CIGS solar cells. These theories propose that the nanodomains may form complex 3D intertwined p-n networks that enhance device performance.Recent experimental evidence offers some support for the existence of nanodomains in CIGS thin films. This study utilizes CIGS solar cells to examine general and CIGS-specific concepts in nanoscale interdigitated solar cells.

  6. Photonic Crystals Towards Nanoscale Photonic Devices

    CERN Document Server

    Lourtioz, Jean-Michel; Berger, Vincent; Gérard, Jean-Michel; Maystre, Daniel; Tchelnokov, Alexis

    2005-01-01

    Just like the periodical crystalline potential in solid-state crystals determines their properties for the conduction of electrons, the periodical structuring of photonic crystals leads to envisioning the possibility of achieving a control of the photon flux in dielectric and metallic materials. The use of photonic crystals as a cage for storing, filtering or guiding light at the wavelength scale thus paves the way to the realisation of optical and optoelectronic devices with ultimate properties and dimensions. This should contribute toward meeting the demands for a greater miniaturisation that the processing of an ever increasing number of data requires. Photonic Crystals intends at providing students and researchers from different fields with the theoretical background needed for modelling photonic crystals and their optical properties, while at the same time presenting the large variety of devices, from optics to microwaves, where photonic crystals have found applications. As such, it aims at building brid...

  7. Photonic Crystals Towards Nanoscale Photonic Devices

    CERN Document Server

    Lourtioz, Jean-Michel; Berger, Vincent; Gérard, Jean-Michel; Maystre, Daniel; Tchelnokov, Alexei; Pagnoux, Dominique

    2008-01-01

    Just like the periodical crystalline potential in solid state crystals determines their properties for the conduction of electrons, the periodical structuring of photonic crystals leads to envisioning the possibility of achieving a control of the photon flux in dielectric and metallic materials. The use of photonic crystals as cages for storing, filtering or guiding light at the wavelength scale paves the way to the realization of optical and optoelectronic devices with ultimate properties and dimensions. This will contribute towards meeting the demands for greater miniaturization imposed by the processing of an ever increasing number of data. Photonic Crystals will provide students and researchers from different fields with the theoretical background required for modelling photonic crystals and their optical properties, while at the same time presenting the large variety of devices, ranging from optics to microwaves, where photonic crystals have found application. As such, it aims at building bridges between...

  8. Nanoscale growth twins in sputtered metal films

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Amit [Los Alamos National Laboratory; Anderoglu, Osman [Los Alamos National Laboratory; Hoagland, Richard G [Los Alamos National Laboratory; Zhang, X [TEXAS A& M

    2008-01-01

    We review recent studies on the mechanical properties of sputtered Cu and 330 stainless steel films with {l_brace}1 1 1{r_brace} nanoscale growth twins preferentially oriented perpendicular to growth direction. The mechanisms of formation of growth twins during sputtering and the deformation mechanisms that enable usually high strengths in nanotwinned structures are highlighted. Growth twins in sputtered films possess good thermal stability at elevated temperature, providing an approach to extend the application of high strength nanostructured metals to higher temperatures.

  9. Thermal measurement. Nanoscale temperature mapping in operating microelectronic devices.

    Science.gov (United States)

    Mecklenburg, Matthew; Hubbard, William A; White, E R; Dhall, Rohan; Cronin, Stephen B; Aloni, Shaul; Regan, B C

    2015-02-06

    Modern microelectronic devices have nanoscale features that dissipate power nonuniformly, but fundamental physical limits frustrate efforts to detect the resulting temperature gradients. Contact thermometers disturb the temperature of a small system, while radiation thermometers struggle to beat the diffraction limit. Exploiting the same physics as Fahrenheit's glass-bulb thermometer, we mapped the thermal expansion of Joule-heated, 80-nanometer-thick aluminum wires by precisely measuring changes in density. With a scanning transmission electron microscope and electron energy loss spectroscopy, we quantified the local density via the energy of aluminum's bulk plasmon. Rescaling density to temperature yields maps with a statistical precision of 3 kelvin/hertz(-1/2), an accuracy of 10%, and nanometer-scale resolution. Many common metals and semiconductors have sufficiently sharp plasmon resonances to serve as their own thermometers. Copyright © 2015, American Association for the Advancement of Science.

  10. Micro- and nano-scale optoelectronic devices using vanadium dioxide

    Science.gov (United States)

    Joushaghani, Arash

    Miniaturization has the potential to reduce the size, cost, and power requirements of active optical devices. However, implementing (sub)wavelength-scale electro-optic switches with high efficiency, low insertion loss, and high extinction ratios remains challenging due to their small active volumes. Here, we use the insulator-metal phase transition of vanadium dioxide (VO2), which exhibits a large and reversible change in the refractive index across the phase transition to demonstrate compact, broadband, and efficient switches and photodetectors with record-setting characteristics. We begin by analyzing the electrical and optical properties of VO2 thin films across the phase transition and discuss the fabrication processes that yield micron- and nano-scale VO2 devices. We then demonstrate a surface plasmon thermo-optic switch, which achieves an extinction ratio of 10 dB in a 5 um long device, a record for plasmonic devices. The switch operates over a 100 nm optical bandwidth, and exhibits a thermally limited switching time of 40 mus. We investigate the current and voltage induced switching of VO2 in nano-gap junctions and show optical switching times as short as 20 ns. The two terminal VO2 junctions are incorporated in a silicon photonics platform to yield silicon-VO2 hybrid waveguide devices with a record extinction ratio of 12 dB in a 1 mum long device. In photodetector mode, the devices exhibit a nonlinear responsivity greater than 12 A/W for optical powers less than 1 muW. This device is the smallest electrically controlled and integrated switch and photodetector capable of achieving extinction ratios > 10 dB/mum. We finally investigate the ultra-fast thermal heating in gold nano-apertures and demonstrate that electron heating can change the gold lattice temperature by 300 K in tens of picoseconds. These nano-apertures can be hybridized with VO2 to demonstrate high extinction and ultrafast optical switches.

  11. Structure of nanoscale gas bubbles in metals

    Energy Technology Data Exchange (ETDEWEB)

    Caro, A., E-mail: caro@lanl.gov; Schwen, D.; Martinez, E. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2013-11-18

    A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2γ/R, with γ the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1 nm and below.

  12. Investigation of nanoscale magnetic materials and devices

    Science.gov (United States)

    Rench, David William

    A host of fundamentally and technologically intriguing phenomena can be observed in ferromagnetic systems, ranging from Giant Magnetoresistance (GMR) to spin structures that approximate the non-zero entropy state of water ice. In this dissertation, we consider systems of self-assembled MnAs nanoclusters in a doped GaAs matrix, a magnetically-doped topological insulator material, and magnetotransport devices constructed as artificial spin ices. We performed magnetic, structural, and electronic measurements in each of the projects herein to discover unique materials properties that range from new phase diagrams to electronic structure breaking and intriguing electrical characteristics that seem to defy the symmetry of the system that manifests them. We first explore the impact of co-doping a GaAs semiconductor matrix with magnetic and non-magnetic dopant ions (Mn and Be, respectively) and forcing phase separation to occur during the sample growth stage. The result of this phase-separated co-doped growth was the identification of two distinct materials classes: Type I materials, in which the phase separation produces ferromagnetic zinc blende (Mn,Ga)As nanoclusters with a narrow distribution of small diameters within a weakly Be-doped GaAs matrix, and Type II materials, in which an abrupt mixing of large NiAs-type MnAs nanoclusters and the small (Mn,Ga)As nanoclusters occurs. These two states are shown to also have accessible intermediate states in the case of a doped substrate and buffer layer. Magnetic measurements are performed to determine the dynamics of the unmixed Type I and the mixed Type II materials. Structural characteristization is done at the nanoscale in a variety of instruments to precisely determine the likely growth dynamics during sample synthesis and the resultant structures. The materials are found to be superparamagnetic with 10 K (Type I) and approximately 313 K (Type II) blocking temperatures with a strong dependence on Mn content during growth

  13. Nanoscale transfer printing for heterogeneous device integration (Conference Presentation)

    Science.gov (United States)

    Hurtado, Antonio; Guilhabert, Benoit J. E.; Strain, Michael J.; Laurand, Nicolas; Jagadish, Chennupati; Dawson, Martin D.

    2017-02-01

    We present a novel nanoscale transfer printing (TP) technology which combines a customized nanolithography system with bespoke elastomeric μ-stamps to controllably pick and place diverse semiconductor structures, e.g. nanowires (NWs), Light Emitting Diodes (LEDs) and thin films, onto targeted locations on heterogeneous material surfaces (e.g. polymers, metals, silica, diamond). Notably, our technique allows the parallel printing of semiconductor structures of different materials onto a large area (of 10cm x 10cm) whilst simultaneously yielding sub-micrometric positioning control (down to below 100nm) and low printing time ( 20s per print step). In the talk, we will present a variety of hybrid integrated devices fabricated with our TP technique. Emphasis will be given to our recent work using Gallium Nitride (GaN) LEDs and Indium Phosphide (InP) NW lasers as building blocks. Using TP protocols, GaN LEDs fabricated from GaN-on-Si have been integrated onto polymer and thin glass surfaces and onto diamond substrates for mechanically flexible optoelectronic devices and effective device heat management respectively. Additionally, ultra-small InP NW lasers ( 5μm long and 500nm diameter) have been integrated onto multiple heterogeneous substrates, including mechanically flexible (polymers), transparent (silica) and metallic (gold) surfaces. Furthermore, complex spatial patterns with micrometric dimensions have been defined with these nanolasers acting as localised emitters. Finally, we will also introduce our very recent results demonstrating the coupling of InP NW lasers with planar waveguide technology as a back-end hybrid integration technique.

  14. Thermoelectric efficiency of nanoscale devices in the linear regime

    Science.gov (United States)

    Bevilacqua, G.; Grosso, G.; Menichetti, G.; Pastori Parravicini, G.

    2016-12-01

    We study quantum transport through two-terminal nanoscale devices in contact with two particle reservoirs at different temperatures and chemical potentials. We discuss the general expressions controlling the electric charge current, heat currents, and the efficiency of energy transmutation in steady conditions in the linear regime. With focus in the parameter domain where the electron system acts as a power generator, we elaborate workable expressions for optimal efficiency and thermoelectric parameters of nanoscale devices. The general concepts are set at work in the paradigmatic cases of Lorentzian resonances and antiresonances, and the encompassing Fano transmission function: the treatments are fully analytic, in terms of the trigamma functions and Bernoulli numbers. From the general curves here reported describing transport through the above model transmission functions, useful guidelines for optimal efficiency and thermopower can be inferred for engineering nanoscale devices in energy regions where they show similar transmission functions.

  15. Nanoscale Copper and Copper Compounds for Advanced Device Applications

    Science.gov (United States)

    Chen, Lih-Juann

    2016-12-01

    Copper has been in use for at least 10,000 years. Copper alloys, such as bronze and brass, have played important roles in advancing civilization in human history. Bronze artifacts date at least 6500 years. On the other hand, discovery of intriguing properties and new applications in contemporary technology for copper and its compounds, particularly on nanoscale, have continued. In this paper, examples for the applications of Cu and Cu alloys for advanced device applications will be given on Cu metallization in microelectronics devices, Cu nanobats as field emitters, Cu2S nanowire array as high-rate capability and high-capacity cathodes for lithium-ion batteries, Cu-Te nanostructures for field-effect transistor, Cu3Si nanowires as high-performance field emitters and efficient anti-reflective layers, single-crystal Cu(In,Ga)Se2 nanotip arrays for high-efficiency solar cell, multilevel Cu2S resistive memory, superlattice Cu2S-Ag2S heterojunction diodes, and facet-dependent Cu2O diode.

  16. Metallic spintronic devices

    CERN Document Server

    Wang, Xiaobin

    2014-01-01

    Metallic Spintronic Devices provides a balanced view of the present state of the art of metallic spintronic devices, addressing both mainstream and emerging applications from magnetic tunneling junction sensors and spin torque oscillators to spin torque memory and logic. Featuring contributions from well-known and respected industrial and academic experts, this cutting-edge work not only presents the latest research and developments but also: Describes spintronic applications in current and future magnetic recording devicesDiscusses spin-transfer torque magnetoresistive random-access memory (STT-MRAM) device architectures and modelingExplores prospects of STT-MRAM scaling, such as detailed multilevel cell structure analysisInvestigates spintronic device write and read optimization in light of spintronic memristive effectsConsiders spintronic research directions based on yttrium iron garnet thin films, including spin pumping, magnetic proximity, spin hall, and spin Seebeck effectsProposes unique solutions for ...

  17. Imaging ultrafast carrier transport in nanoscale devices using femtosecond photocurrent microscopy

    CERN Document Server

    Son, B H; Hong, J T; Park, Ji-Yong; Lee, Soonil; Ahn, Y H

    2014-01-01

    One-dimensional nanoscale devices, such as semiconductor nanowires (NWs) and single- walled carbon nanotubes (SWNTs), have been intensively investigated because of their potential application of future high-speed electronic, optoelectronic, and sensing devices. To overcome current limitations on the speed of contemporary devices, investigation of charge carrier dynamics with an ultrashort time scale is one of the primary steps necessary for developing high-speed devices. In the present study, we visualize ultrafast carrier dynamics in nanoscale devices using a combination of scanning photocurrent microscopy and time- resolved pump-probe techniques. We investigate transit times of carriers that are generated near one metallic electrode and subsequently transported toward the opposite electrode based on drift and diffusion motions. Carrier dynamics have been measured for various working conditions. In particular, the carrier velocities extracted from transit times increase for a larger negative gate bias, becau...

  18. Optical Biosensors: A Revolution Towards Quantum Nanoscale Electronics Device Fabrication

    Directory of Open Access Journals (Sweden)

    D. Dey

    2011-01-01

    Full Text Available The dimension of biomolecules is of few nanometers, so the biomolecular devices ought to be of that range so a better understanding about the performance of the electronic biomolecular devices can be obtained at nanoscale. Development of optical biomolecular device is a new move towards revolution of nano-bioelectronics. Optical biosensor is one of such nano-biomolecular devices that has a potential to pave a new dimension of research and device fabrication in the field of optical and biomedical fields. This paper is a very small report about optical biosensor and its development and importance in various fields.

  19. Semiempirical model for nanoscale device simulations

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Petersen, Dan Erik; Smidstrup, Søren;

    2010-01-01

    We present a semiempirical model for calculating electron transport in atomic-scale devices. The model is an extension of the extended Hückel method with a self-consistent Hartree potential that models the effect of an external bias and corresponding charge rearrangements in the device. It is als...

  20. Computational aspects of electronic transport in nanoscale devices

    DEFF Research Database (Denmark)

    Sørensen, Hans Henrik Brandenborg

    2008-01-01

    This thesis is concerned with the modeling of electronic properties of nano-scale devices. In particular the computational aspects of calculating the transmission and current-voltage characteristics of Landauer-Büttiker two-probe systems are in focus. To begin with, the main existing methods...

  1. Manufacturing and Reliability of Nanoscale Devices

    Science.gov (United States)

    Loh, Owen Yin

    The International Technology Roadmap for Semiconductors (ITRS) identifies emerging technologies with the potential to sustain Moore's Law. A necessary progression from conventional CMOS, to non-planer/dual gate CMOS, and ultimately to novel device architectures such as nanoelectromechanical systems (NEMS) is envisioned. The ITRS also identifies critical roadblocks which currently preclude advances beyond CMOS as a means to guide research and development efforts. Roadblocks specific to NEMS include widespread manufacturing challenges associated with manipulating one-dimensional nanostructures, and poor reliability arising from a number of prevalent failure modes. The weight of these roadblocks is evident well beyond the goals of the ITRS, where nanoelectromechanical sensors and other devices face similar obstacles. This thesis focuses on two critical challenges facing the development of robust carbon nanotube-based NEMS: scalable manufacturing methods, and understanding and eliminating prevalent failure modes. Toward the first challenge, probe-based nanomanufacturing schemes are developed to construct well-ordered arrays of individual carbon nanotubes from which NEMS can be fabricated. This work extends beyond the goals of the semiconductor industry, and demonstrates the ability to create functional sub-100-nanometer protein and drug arrays, as well as novel in vitro injection methods for single cell studies. The second part of this thesis indentifies prevalent failure modes and their point of onset within the device design space. Again, these are addressed by the ITRS but have implications reaching well beyond the semiconductor industry. It then seeks to find the underlying mechanisms for the observed failure modes, and introduces easily-implemented solutions which exhibit the ability to eliminate or greatly-suppress the prevalent failure modes, enabling numerous device actuation cycles without failure and demonstrations of functionality not possible with failure

  2. A transition in mechanisms of size dependent electrical transport at nanoscale metal-oxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Jiechang; Nonnenmann, Stephen S.; Qin, Wei; Bonnell, Dawn A., E-mail: bonnell@lrsm.seas.upenn.edu [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2013-12-16

    As device miniaturization approaches nanoscale dimensions, interfaces begin to dominate electrical properties. Here the system archetype Au/SrTiO{sub 3} is used to examine the origin of size dependent transport properties along metal-oxide interfaces. We demonstrate that a transition between two classes of size dependent electronic transport mechanisms exists, defined by a critical size ε. At sizes larger than ε an edge-related tunneling effect proportional to 1/D (the height of the supported Au nanoparticle) is observed; interfaces with sizes smaller than ε exhibit random fluctuations in current. The ability to distinguish between these mechanisms is important to future developments in nanoscale device design.

  3. Time-Dependent Transport in Nanoscale Devices

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhi-Dong; ZHANG Jin-Yu; YU Zhi-Ping

    2009-01-01

    A method for simulating ballistic time-dependent device transport,which solves the time-dependent SchrSdinger equation using the finite difference time domain (FDTD) method together with Poisson's equation,is described in detail The effective mass SchrSdinger equation is solved. The continuous energy spectrum of the system is discretized using adaptive mesh,resulting in energy levels that sample the density-of-states.By calculating time evolution of wavefunctions at sampled energies,time-dependent transport characteristics such as current and charge density distributions are obtained.Simulation results in a uanowire and a coaxially gated carbon nanotube field-effect transistor (CNTFET) are presented.Transient effects,e.g.,finite rising time,are investigated in these devices.

  4. Nanoscale Metal Oxide Semiconductors for Gas Sensing

    Science.gov (United States)

    Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

    2011-01-01

    A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical

  5. Nanoscale selective area epitaxy for optoelectronic devices

    Science.gov (United States)

    Elarde, V. C.; Coleman, J. J.

    Self-assembled quantum dots have been heavily researched in recent years because of the potential applications to quantum electronic and optoelectronic devices they present. The non-uniformity and random ordering resulting from the self-assembly processes, however, are detrimental to potential applications, prohibiting the type of engineering control necessary for complex systems. The work presented in this document has sought to overcome the limitations of self-assembly by combining selective area epitaxy via MOCVD with high-resolution electron beam lithography to achieve lateral control over semiconductor structures at the nanometer scale. Two different structures are presented. The first is patterned quantum dots which improve on the uniformity and order of similar self-assembled quantum dots. The second is an entirely novel structure, the nanopore active layer, which demonstrates the potential for this process to extend beyond the constraints of self-assembly. Experimental and theoretical results for both structures are presented.

  6. Magnetization switching schemes for nanoscale three-terminal spintronics devices

    Science.gov (United States)

    Fukami, Shunsuke; Ohno, Hideo

    2017-08-01

    Utilizing spintronics-based nonvolatile memories in integrated circuits offers a promising approach to realize ultralow-power and high-performance electronics. While two-terminal devices with spin-transfer torque switching have been extensively developed nowadays, there has been a growing interest in devices with a three-terminal structure. Of primary importance for applications is the efficient manipulation of magnetization, corresponding to information writing, in nanoscale devices. Here we review the studies of current-induced domain wall motion and spin-orbit torque-induced switching, which can be applied to the write operation of nanoscale three-terminal spintronics devices. For domain wall motion, the size dependence of device properties down to less than 20 nm will be shown and the underlying mechanism behind the results will be discussed. For spin-orbit torque-induced switching, factors governing the threshold current density and strategies to reduce it will be discussed. A proof-of-concept demonstration of artificial intelligence using an analog spin-orbit torque device will also be reviewed.

  7. Development of Nanoscale Graphitic Devices and The Transport Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Gunasekaran, Venugopal

    2011-02-15

    This dissertation describes the development of graphitic based nanoscale devices with its fabrication and transport characterization results. It covers graphite nano-scale stacked-junctions fabricated using focused ion beam (FIB) 3-D etching technique, a single layer graphite layer (graphene) preparation and its electrical transport characterization results and the synthesis and investigation of electrical transport behavior of graphene oxide based thin film devices. The first chapter describes the basic information about the carbon family in detail in which the electronic properties and structure of graphite, graphene and graphene oxide are discussed. In addition, the necessity of developing nanoscale graphitic devices is given. The second chapter explains the experimental techniques used in this research for fabricating nanoscale devices which includes focused ion beam 3-D fabrication procedures, mechanical exfoliation technique and photolithographic methods. In third chapter, we have reported the results on temperature dependence of graphite planar-type structures fabricated along ab-plane. In the fourth and fifth chapters, the fabrication and electrical transport characteristics of large in-plane area graphite planar-type structures (fabricated along ab-plane and c-axis) were discussed and their transport anisotropy properties were investigated briefly. In the sixth chapter, we focused the fabrication of the submicron sized graphite stacked junctions and their electrical transport characterization studies. In which, FIB was used to fabricated the submicron junctions with various in-plane area (with same stack height) are and their transport characteristics were compared. The seventh chapter reports investigation of electrical transport results of nanoscale graphite stacked-junctions in which the temperature dependent transport (R-T) studies, current-voltage measurements for the various in-plane areas and for various stack height samples were analyzed. The

  8. Micro/nanoscale patterning of nanostructured metal substrates for plasmonic applications.

    Science.gov (United States)

    Shankar, S Shiv; Rizzello, Loris; Cingolani, Roberto; Rinaldi, Ross; Pompa, Pier Paolo

    2009-04-28

    The ability to precisely control the pattern of different metals at the micro- and nanoscale, along with their topology, has been demonstrated to be essential for many applications, ranging from material science to biomedical devices, electronics, and photonics. In this work, we show a novel approach, based on a combination of lithographic techniques and galvanic displacement reactions, to fabricate micro- and nanoscale patterns of different metals, with highly controlled surface roughness, onto a number of suitable substrates. We demonstrate the possibility to exploit such metal films to achieve significant fluorescence enhancement of nearby fluorophores, while maintaining accurate spatial control of the process, from submicron resolution to centimeter-sized features. These patterns may be also exploited for a wide range of applications, including SERS, solar cells, DNA microarray technology, hydrophobic/hydrophilic substrates, and magnetic devices.

  9. Electrode-stress-induced nanoscale disorder in Si quantum electronic devices

    Science.gov (United States)

    Park, J.; Ahn, Y.; Tilka, J. A.; Sampson, K. C.; Savage, D. E.; Prance, J. R.; Simmons, C. B.; Lagally, M. G.; Coppersmith, S. N.; Eriksson, M. A.; Holt, M. V.; Evans, P. G.

    2016-06-01

    Disorder in the potential-energy landscape presents a major obstacle to the more rapid development of semiconductor quantum device technologies. We report a large-magnitude source of disorder, beyond commonly considered unintentional background doping or fixed charge in oxide layers: nanoscale strain fields induced by residual stresses in nanopatterned metal gates. Quantitative analysis of synchrotron coherent hard x-ray nanobeam diffraction patterns reveals gate-induced curvature and strains up to 0.03% in a buried Si quantum well within a Si/SiGe heterostructure. Electrode stress presents both challenges to the design of devices and opportunities associated with the lateral manipulation of electronic energy levels.

  10. Attosecond physics at a nanoscale metal tip

    Directory of Open Access Journals (Sweden)

    Lemell Christoph

    2013-03-01

    Full Text Available With few-cycle laser oscillator pulses at 800 nm we observe strong-field and attosecond physics phenomena in electron spectra recorded at a nanoscale tungsten tip. We observe the rescattering plateau as well as a strong carrier-envelope phase dependence of the spectra. We model the results with the semiclassical three-step model as well as with time-dependent density functional theory.

  11. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G

    1986-01-01

    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  12. Nanoscale temperature sensor based on Fano resonance in metal-insulator-metal waveguide

    Science.gov (United States)

    Kong, Yan; Wei, Qi; Liu, Cheng; Wang, Shouyu

    2017-02-01

    In order to realize temperature measurements with high sensitivity using compact structure, a nanoscale metal-insulator-metal waveguide based sensor combining with Fano resonance is proposed in this paper. Sealed ethanol in resonant cavity is adopted to further improve sensing performance. Additionally, dual resonant cavity based configuration is designed to generate a Fano-based sharp and asymmetric spectrum, providing high figure of merit in measurements. Moreover, structural parameters are optimized considering both transmission rate and spectral peak width. Certified by numerical calculation, sensitivity of 0.36 nm/°C is acquired with the optimized structure, indicating the designed sensor can play an important role in the nano-integrated plasmonic devices for high-accurate temperature detection.

  13. Integration of molecular functions into Si device for nanoscale molecular devices

    Energy Technology Data Exchange (ETDEWEB)

    Wakayama, Yutaka, E-mail: WAKAYAMA.Yutaka@nims.go.jp; Hayakawa, Ryoma

    2014-03-03

    Recent progress on nanoscale molecular devices is reviewed. The advantages of organic molecules are highlighted in terms of their unique features such as quantum effects based on their nanometer size, optical properties originating from photochromism and chemical syntheses for various structural designs. This review covers three topics: a scanning probe microscope-based evaluation of individual molecules, nano-gap electrodes for electrical current through single-molecules and the incorporation of molecular functions into Si-based devices. In particular, the importance of the incorporation of organic molecules into Si-device architecture is emphasized with a view to realizing the large-scale integration of nanoscale molecular devices. - Highlights: • Scanning probe microscope-based evaluation of individual molecules; • Nano-gap electrodes for electrical current through single-molecules; • Incorporation of molecular functions into Si-based devices.

  14. Bottom-up synthesis of ordered metal/oxide/metal nanodots on substrates for nanoscale resistive switching memory

    Science.gov (United States)

    Han, Un-Bin; Lee, Jang-Sik

    2016-01-01

    The bottom-up approach using self-assembled materials/processes is thought to be a promising solution for next-generation device fabrication, but it is often found to be not feasible for use in real device fabrication. Here, we report a feasible and versatile way to fabricate high-density, nanoscale memory devices by direct bottom-up filling of memory elements. An ordered array of metal/oxide/metal (copper/copper oxide/copper) nanodots was synthesized with a uniform size and thickness defined by self-organized nanotemplate mask by sequential electrochemical deposition (ECD) of each layer. The fabricated memory devices showed bipolar resistive switching behaviors confirmed by conductive atomic force microscopy. This study demonstrates that ECD with bottom-up growth has great potential to fabricate high-density nanoelectronic devices beyond the scaling limit of top-down device fabrication processes. PMID:27157385

  15. Deformation of a ceramic/metal interface at the nanoscale.

    Science.gov (United States)

    Jiang, Lin; Hu, Tao; Yang, Hanry; Zhang, Dalong; Topping, Troy; Lavernia, Enrique J; Schoenung, Julie M

    2016-05-19

    The mechanical response of heterophase interfaces has attracted substantial attention in recent years. Here, we utilized an in situ transmission electron microscopy (TEM) technique to isolate an individual nanoscale ceramic/metal interface and characterize its nanomechanical response. The interface, at which there was a Mg-rich segregation nanolayer between the single crystal ceramic (B4C) and the polycrystalline metal (Al alloy, AA5083), was determined to have a bond strength greater than 1.5 GPa. Bimodal failure and metallic grain rotation occurred in the metallic region, allowing the interface to accommodate a deformation strain of 5.4%. The roles of elemental segregation and nanoscale dimensions on interfacial debonding mechanisms are discussed.

  16. Instability of nanoscale metallic particles under electron irradiation in TEM

    Science.gov (United States)

    Chen, X. Y.; Zhang, S. G.; Xia, M. X.; Li, J. G.

    2016-03-01

    The stability of nano metallic glass under electron beam in transmission electron microscope (TEM) was investigated. The most common voltage of TEM used in metallic materials characterization was either 200 kV or 300 kV. Both situations were investigated in this work. An amorphous metallic particle with a dimension of a few hundred nanometers was tested under 300 keV electron irradiation. New phase decomposed from the parent phase was observed. Moreover, a crystal particle with the same composition and dimension was tested under 200 keV irradiation. Decomposition process also occurred in this situation. Besides, crystal orientation modification was observed during irradiation. These results proved that the electron beam in TEM have an effect on the stability of nanoscale samples during long time irradiation. Atomic displacement was induced and diffusion was enhanced by electron irradiation. Thus, artifacts would be induced when a nanoscale metallic sample was characterized in TEM.

  17. A hyperlens-based device for nanoscale focusing of light

    Institute of Scientific and Technical Information of China (English)

    Jiangnan Zhao; Guoxing Zheng; Song Li; Hui Zhou; Yue Ma; Ruiying Zhang; Yah Shi; Ping'an He

    2012-01-01

    To resolve the problem of missed evanescent waves in a beam focusing system,a hyperlens-based beam focusing device is proposed in this letter.This device can convert the evanescent waves into propagating waves,and then a super-resolution spot is formed at the center of the hyperlens.The working principle of the device is presented,and the way in which the material and structural parameters of the hyperlens affect the resolution and transmission is analyzed in detail. A multibeam focusing device is optimally designed,and the simulated results verify that a nanoscale spot with a diameter of 15.6 nm (corresponding to λ0/24,where λ0 is the working wavelength in vacuum) is achieved,which is far less than the diffraction limited resolution with a value of 625 nm (l.7λ0).The device is expected to find numerous applications in optical data storage and nano-photolithography,among others.

  18. Nanoscale strain engineering of graphene and graphene-based devices

    Science.gov (United States)

    Yeh, N.-C.; Hsu, C.-C.; Teague, M. L.; Wang, J.-Q.; Boyd, D. A.; Chen, C.-C.

    2016-06-01

    Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one atomic layer thickness. In particular, strained graphene can result in both charging effects and pseudo-magnetic fields, so that controlled strain on a perfect graphene lattice can be tailored to yield desirable electronic properties. Here, we describe the theoretical foundation for strain-engineering of the electronic properties of graphene, and then provide experimental evidence for strain-induced pseudo-magnetic fields and charging effects in monolayer graphene. We further demonstrate the feasibility of nano-scale strain engineering for graphene-based devices by means of theoretical simulations and nano-fabrication technology.

  19. Methods and devices for fabricating three-dimensional nanoscale structures

    Science.gov (United States)

    Rogers, John A.; Jeon, Seokwoo; Park, Jangung

    2010-04-27

    The present invention provides methods and devices for fabricating 3D structures and patterns of 3D structures on substrate surfaces, including symmetrical and asymmetrical patterns of 3D structures. Methods of the present invention provide a means of fabricating 3D structures having accurately selected physical dimensions, including lateral and vertical dimensions ranging from 10s of nanometers to 1000s of nanometers. In one aspect, methods are provided using a mask element comprising a conformable, elastomeric phase mask capable of establishing conformal contact with a radiation sensitive material undergoing photoprocessing. In another aspect, the temporal and/or spatial coherence of electromagnetic radiation using for photoprocessing is selected to fabricate complex structures having nanoscale features that do not extend entirely through the thickness of the structure fabricated.

  20. Nanoscale strain engineering of graphene and graphene-based devices

    Institute of Scientific and Technical Information of China (English)

    N-C Yeh; C-C Hsu; M L Teague; J-Q Wang; D A Boyd; C-C Chen

    2016-01-01

    Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one atomic layer thickness. In particular, strained graphene can result in both charging effects and pseudo-magnetic fields, so that controlled strain on a perfect graphene lattice can be tailored to yield desirable electronic properties. Here, we describe the theoretical foundation for strain-engineering of the electronic properties of graphene, and then provide experimental evidence for strain-induced pseudo-magnetic fields and charging effects in monolayer graphene. We further demonstrate the feasibility of nano-scale strain engineering for graphene-based devices by means of theoretical simula-tions and nano-fabrication technology.

  1. Advances in neuromorphic hardware exploiting emerging nanoscale devices

    CERN Document Server

    2017-01-01

    This book covers all major aspects of cutting-edge research in the field of neuromorphic hardware engineering involving emerging nanoscale devices. Special emphasis is given to leading works in hybrid low-power CMOS-Nanodevice design. The book offers readers a bidirectional (top-down and bottom-up) perspective on designing efficient bio-inspired hardware. At the nanodevice level, it focuses on various flavors of emerging resistive memory (RRAM) technology. At the algorithm level, it addresses optimized implementations of supervised and stochastic learning paradigms such as: spike-time-dependent plasticity (STDP), long-term potentiation (LTP), long-term depression (LTD), extreme learning machines (ELM) and early adoptions of restricted Boltzmann machines (RBM) to name a few. The contributions discuss system-level power/energy/parasitic trade-offs, and complex real-world applications. The book is suited for both advanced researchers and students interested in the field.

  2. Recent Advances in Organic Photovoltaics: Device Structure and Optical Engineering Optimization on the Nanoscale.

    Science.gov (United States)

    Luo, Guoping; Ren, Xingang; Zhang, Su; Wu, Hongbin; Choy, Wallace C H; He, Zhicai; Cao, Yong

    2016-03-23

    Organic photovoltaic (OPV) devices, which can directly convert absorbed sunlight to electricity, are stacked thin films of tens to hundreds of nanometers. They have emerged as a promising candidate for affordable, clean, and renewable energy. In the past few years, a rapid increase has been seen in the power conversion efficiency of OPV devices toward 10% and above, through comprehensive optimizations via novel photoactive donor and acceptor materials, control of thin-film morphology on the nanoscale, device structure developments, and interfacial and optical engineering. The intrinsic problems of short exciton diffusion length and low carrier mobility in organic semiconductors creates a challenge for OPV designs for achieving optically thick and electrically thin device structures to achieve sufficient light absorption and efficient electron/hole extraction. Recent advances in the field of OPV devices are reviewed, with a focus on the progress in device architecture and optical engineering approaches that lead to improved electrical and optical characteristics in OPV devices. Successful strategies are highlighted for light wave distribution, modulation, and absorption promotion inside the active layer of OPV devices by incorporating periodic nanopatterns/nanostructures or incorporating metallic nanomaterials and nanostructures.

  3. Segmented metal nanowires as nanoscale thermocouples.

    Science.gov (United States)

    Shapira, E; Marchak, D; Tsukernik, A; Selzer, Y

    2008-03-26

    Segmented Au-Ni nanowires are demonstrated to be highly effective thermocouples with a spatial resolution of a few nanometers and a temporal resolution in the microsecond range. The performance of the devices is characterized by a self-heating procedure in which an ac heating current with frequency ω is applied on the wires while monitoring the resulting thermoelectric voltage V(TH) at 2ω using a lock-in technique. An analytical model is developed that enables one to determine the time response of the thermocouples from plots of V(TH) as a function of ω.

  4. Electrode-stress-induced nanoscale disorder in Si quantum electronic devices

    Directory of Open Access Journals (Sweden)

    J. Park

    2016-06-01

    Full Text Available Disorder in the potential-energy landscape presents a major obstacle to the more rapid development of semiconductor quantum device technologies. We report a large-magnitude source of disorder, beyond commonly considered unintentional background doping or fixed charge in oxide layers: nanoscale strain fields induced by residual stresses in nanopatterned metal gates. Quantitative analysis of synchrotron coherent hard x-ray nanobeam diffraction patterns reveals gate-induced curvature and strains up to 0.03% in a buried Si quantum well within a Si/SiGe heterostructure. Electrode stress presents both challenges to the design of devices and opportunities associated with the lateral manipulation of electronic energy levels.

  5. Physics and performance of nanoscale semiconductor devices at cryogenic temperatures

    Science.gov (United States)

    Balestra, F.; Ghibaudo, G.

    2017-02-01

    The physics and performance of various advanced semiconductor devices, which are the most promising for the end of the ITRS roadmap, are investigated in a wide temperature range down to 20 K. The transport parameters in front and/or back channels in fully depleted ultrathin film SOI devices, Trigate, FinFET, Omega-gate nanowire FET and 3D-stacked SiGe nanowire FETs, fabricated with high-k dielectrics/metal gate, elevated source/drain, different channel orientations, shapes and strains, are addressed. The impacts of the gate length, Si film and wire diameter down to 10 nm, are also shown. The variations of the phonon, Coulomb, neutral defects and surface roughness scattering as a function of temperature and device architecture are highlighted. An overview of the influence of temperature on other main electrical parameters of MOSFETs, nanowires FETs and tunnel FETs, such as threshold voltage, subthreshold swing, leakage and driving currents is also given.

  6. Nanoscale Materials and Devices - New Solutions for Information Technologies

    Science.gov (United States)

    Buhrman, Robert

    2003-03-01

    The continual scaling down of Si C-MOS circuits, the current annual doubling of magnetic storage density, and the regularly increasing capacity of fiber optic communications have resulted in enormous technological change, including a revolutionary transformation of all areas of science and engineering. Indeed the current capabilities of these information technologies both provide the quintessential demonstration that microtechnology, which is now transitioning to nanotechnology, can have tremendous societal impact, and provide essential means and methods by which other aspects of nanotechnology R can now be pursued. If the pace of advance in these information technologies is to be continued well into the future, new approaches and new solutions will be required to overcome the challenges this objective will entail. Nanoscaled material systems and new types of nanoscale devices have substantial promise for providing the basis for effective solutions to a number of these challenges. In this presentation I will briefly discuss research in the areas of nanoelectronics, nanophotonics and nanomagnetics that seeks to establish and develop some of these solutions. These include a radical new approach to Si electronics at the 10 nm scale, the use of nanoscaled materials to enable new photonic capabilities, and a new approach to manipulate nanomagnets for potential information storage and communication applications.

  7. NMR probe of metallic states in nanoscale topological insulators.

    Science.gov (United States)

    Koumoulis, Dimitrios; Chasapis, Thomas C; Taylor, Robert E; Lake, Michael P; King, Danny; Jarenwattananon, Nanette N; Fiete, Gregory A; Kanatzidis, Mercouri G; Bouchard, Louis-S

    2013-01-11

    A 125Te NMR study of bismuth telluride nanoparticles as a function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from the single to the bimodal regime. The satellite peak features a negative Knight shift and higher relaxivity, consistent with core polarization from p-band carriers. Whereas nanocrystals follow a Korringa law in the range 140-420 K, micrometer particles do so only below 200 K. The results reveal increased metallicity of these nanoscale topological insulators in the limit of higher surface-to-volume ratios.

  8. Analysis of self-propagating intermetallic reaction in nanoscale multilayers of binary metals

    Science.gov (United States)

    Kim, Kyoungjin

    2017-03-01

    Nanoscale multilayers of two different metals could exhibit super-fast intermetallic reaction wave that accompanies high level of exothermic heat release, while additional advantage is a very small ignition delay. They could be a promising candidate for the core technology in realizing micron-sized initiation device for explosives detonation or propellants ignition in various defense and civilian applications. This numerical investigation focuses on the numerical modeling and computations of the ignition and self-propagating reaction behaviors in nanoscale intermetallic multilayer structures made of alternating binary metal layers of boron and titanium. Due to thin film nature of metallic multilayers, intermetallic reaction propagation across the repeating bimetallic multilayers is approximated to the one-dimensional transient model of thermal diffusion and atomic species diffusion, and the intermetallic reaction between two metal species is assumed to follow Arrhenius dependence on temperature. The computational results show the details of ignition and propagation characteristics of intermetallic reaction wave by evaluating and discussing the effects of key parameters, such as multilayer thickness, excess of one metal species, and presence of atomic premixing at interface of boron and titanium layers, on ignition delay and propagation speed of self-sustaining reaction wave.

  9. Engineered Bacterial Metal-binding Proteins for Nanoscale Self-assembly and heavy Metal Tolerance

    Science.gov (United States)

    Hall Sedlak, Ruth Amanda

    Implementing biological principles in material synthesis and assembly is one way to expand our abilities to efficiently assemble nanoscale materials and devices. Specifically, recent advances in identifying peptides that bind inorganic materials with high affinity and specificity has spurred investigation of protein models for nanoscale inorganic assembly. This dissertation presents the results of my studies of several E. coli proteins engineered to bind inorganic materials through simple peptide motifs. I demonstrate that these proteins modulate the self-assembly of DNA-based nanostructures and can introduce heavy metal tolerance into metal-sensitive bacteria. Chapter 2 explores use of the engineered F plasmid DNA relaxase/helicase TraI for the self-assembly of complex DNA-protein-gold nanostructures. The full-length protein is engineered with a gold binding motif at an internal permissive site (TraI369GBP1-7x), while a truncated version of TraI is engineered with the same gold binding motif at the C-terminus (TraI361GBP1-7x). Both constructs bind gold nanoparticles while maintaining their DNA binding activity, and transmission electron microscopy reveals TraI369GBP1-7x utilizes its non-specific DNA binding activity to decorate single-stranded and double-stranded DNA with gold nanoparticles. The self assembly principles demonstrated in this work will be fundamental to constructing higher ordered hybrid nanostructures through DNA-protein-nanoparticle interactions. Chapter 3 studies the effects of expressing inorganic binding peptides within cells. I identified a silver binding peptide that, when fused to the periplasmic maltose binding protein, protects E. coli from silver toxicity in batch culture and reduces silver ions to silver nanoparticles within the bacterial periplasm. Engineered metal-ion tolerant microorganisms such as this E. coli could potentially be used in applications ranging from remediation to interrogation of biomolecule-metal interactions in vivo

  10. Charge transport in nanoscale vertical organic semiconductor pillar devices

    Science.gov (United States)

    Wilbers, Janine G. E.; Xu, Bojian; Bobbert, Peter A.; de Jong, Michel P.; van der Wiel, Wilfred G.

    2017-01-01

    We report charge transport measurements in nanoscale vertical pillar structures incorporating ultrathin layers of the organic semiconductor poly(3-hexylthiophene) (P3HT). P3HT layers with thickness down to 5 nm are gently top-contacted using wedging transfer, yielding highly reproducible, robust nanoscale junctions carrying high current densities (up to 106 A/m2). Current-voltage data modeling demonstrates excellent hole injection. This work opens up the pathway towards nanoscale, ultrashort-channel organic transistors for high-frequency and high-current-density operation.

  11. Improving proton therapy by metal-containing nanoparticles: nanoscale insights

    Science.gov (United States)

    Schlathölter, Thomas; Eustache, Pierre; Porcel, Erika; Salado, Daniela; Stefancikova, Lenka; Tillement, Olivier; Lux, Francois; Mowat, Pierre; Biegun, Aleksandra K; van Goethem, Marc-Jan; Remita, Hynd; Lacombe, Sandrine

    2016-01-01

    The use of nanoparticles to enhance the effect of radiation-based cancer treatments is a growing field of study and recently, even nanoparticle-induced improvement of proton therapy performance has been investigated. Aiming at a clinical implementation of this approach, it is essential to characterize the mechanisms underlying the synergistic effects of nanoparticles combined with proton irradiation. In this study, we investigated the effect of platinum- and gadolinium-based nanoparticles on the nanoscale damage induced by a proton beam of therapeutically relevant energy (150 MeV) using plasmid DNA molecular probe. Two conditions of irradiation (0.44 and 3.6 keV/μm) were considered to mimic the beam properties at the entrance and at the end of the proton track. We demonstrate that the two metal-containing nanoparticles amplify, in particular, the induction of nanosize damages (>2 nm) which are most lethal for cells. More importantly, this effect is even more pronounced at the end of the proton track. This work gives a new insight into the underlying mechanisms on the nanoscale and indicates that the addition of metal-based nanoparticles is a promising strategy not only to increase the cell killing action of fast protons, but also to improve tumor targeting. PMID:27143877

  12. Nanoscale guiding for cold atoms based on surface plasmons along the tips of metallic wedges

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng-Ling; Tang Wei-Min; Zhou Ming; Gao Chuan-Yu

    2013-01-01

    We propose a novel scheme to guide neutral cold atoms in a nanoscale region based on surface plasmons (SPs) of one pair and two pairs of tips of metallic wedges with locally enhanced light intensity and sub-optical wavelength resolution.We analyze the near-field intensity distribution of the tip of the metallic wedge by the FDTD method,and study the total intensity as well as the total potential of optical potentials and van der Waals potentials for 87Rb atoms in the light field of one pair and two pairs of tips of metallic wedges.It shows that the total potentials of one pair and two pairs of tips of metallic wedges can generate a gravito-optical trap and a dark closed trap for nanoscale guiding of neutral cold atoms.Guided atoms can be cooled with efficient intensity-gradient Sisyphus cooling by blue-detuned light field.This provides an important step towards the generation of hybrid systems consisting of isolated atoms and solid devices.

  13. Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

    Science.gov (United States)

    Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

    2013-01-01

    Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

  14. The equipment for the preparation of micro and nanoscale metallic glassy fibers.

    Science.gov (United States)

    Ding, D W; Yi, J; Liu, G L; Sun, Y T; Zhao, D Q; Pan, M X; Bai, H Y; Wang, W H

    2014-10-01

    A supercooled liquid extraction method and apparatus for micro and nanoscale metallic glassy fiber preparation was developed. Using the fiber fabrication equipment, micro to nanoscale metallic glassy fibers with diameter ranging from 70 nm to 300 μm can be obtained by wire drawing in the supercooled liquid region of metallic glasses via superplastic deformation. The obtained metallic glassy fibers possess precisely designed and controlled sizes, high structural uniformity and high degree of surface smoothness.

  15. The equipment for the preparation of micro and nanoscale metallic glassy fibers

    Science.gov (United States)

    Ding, D. W.; Yi, J.; Liu, G. L.; Sun, Y. T.; Zhao, D. Q.; Pan, M. X.; Bai, H. Y.; Wang, W. H.

    2014-10-01

    A supercooled liquid extraction method and apparatus for micro and nanoscale metallic glassy fiber preparation was developed. Using the fiber fabrication equipment, micro to nanoscale metallic glassy fibers with diameter ranging from 70 nm to 300 μm can be obtained by wire drawing in the supercooled liquid region of metallic glasses via superplastic deformation. The obtained metallic glassy fibers possess precisely designed and controlled sizes, high structural uniformity and high degree of surface smoothness.

  16. Fabrication of integrated metallic MEMS devices

    DEFF Research Database (Denmark)

    Yalcinkaya, Arda Deniz; Ravnkilde, Jan Tue; Hansen, Ole

    2002-01-01

    A simple and complementary metal oxide semiconductor (CMOS) compatible fabrication technique for microelectromechanical (MEMS) devices is presented. The fabrication technology makes use of electroplated metal layers. Among the fabricated devices, high quality factor microresonators...

  17. Metallic Junction Thermoelectric Device Simulations

    Science.gov (United States)

    Duzik, Adam J.; Choi, Sang H.

    2017-01-01

    Thermoelectric junctions made of semiconductors have existed in radioisotope thermoelectric generators (RTG) for deep space missions, but are currently being adapted for terrestrial energy harvesting. Unfortunately, these devices are inefficient, operating at only 7% efficiency. This low efficiency has driven efforts to make high-figure-of-merit thermoelectric devices, which require a high electrical conductivity but a low thermal conductivity, a combination that is difficult to achieve. Lowered thermal conductivity has increased efficiency, but at the cost of power output. An alternative setup is to use metallic junctions rather than semiconductors as thermoelectric devices. Metals have orders of magnitude more electrons and electronic conductivities higher than semiconductors, but thermal conductivity is higher as well. To evaluate the viability of metallic junction thermoelectrics, a two dimensional heat transfer MATLAB simulation was constructed to calculate efficiency and power output. High Seebeck coefficient alloys, Chromel (90%Ni-10%Cr) and Constantan (55%Cu-45%Ni), produced efficiencies of around 20-30%. Parameters such as the number of layers of junctions, lateral junction density, and junction sizes for both series- and parallel-connected junctions were explored.

  18. Molecular dynamics simulations of nanoscale metal tips under electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Parviainen, S., E-mail: stefan.parviainen@helsinki.fi [Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FIN-00014 Helsinki (Finland); Djurabekova, F.; Pohjonen, A.; Nordlund, K. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FIN-00014 Helsinki (Finland)

    2011-07-15

    Vacuum arcing is a plasma discharge over a metal surface under high electric fields. Plasma formation requires the supply of neutral atoms, which under high vacuum condition can only come from the surface itself. Nevertheless, the mechanisms by which the atoms are supplied are not known. In the present work, we propose a model for the onset of surface roughness and field-enhanced atom evaporation. Specifically, we describe a dislocation mechanism of tip growth from near-surface voids. We also simulate surface charging and resistive heating using a hybrid electrodynamics and molecular dynamics (ED and MD) code for dynamic simulations of electronic effects. We study the morphological evolution of the nanoscale protrusion under the electronic effects, such as the stretching of the tip by the stress induced by the electric field.

  19. Redox deposition of nanoscale metal oxides on carbon for next-generation electrochemical capacitors.

    Science.gov (United States)

    Sassin, Megan B; Chervin, Christopher N; Rolison, Debra R; Long, Jeffrey W

    2013-05-21

    Transition metal oxides that mix electronic and ionic conductivity are essential active components of many electrochemical charge-storage devices, ranging from primary alkaline cells to more advanced rechargeable Li-ion batteries. In these devices, charge storage occurs via cation-insertion/deinsertion mechanisms in conjunction with the reduction/oxidation of metal sites in the oxide. Batteries that incorporate such metal oxides are typically designed for high specific energy, but not necessarily for high specific power. Electrochemical capacitors (ECs), which are typically composed of symmetric high-surface-area carbon electrodes that store charge via double-layer capacitance, deliver their energy in time scales of seconds, but at much lower specific energy than batteries. The fast, reversible faradaic reactions (typically described as "pseudocapacitance") of particular nanoscale metal oxides (e.g., ruthenium and manganese oxides) provide a strategy for bridging the power/energy performance gap between batteries and conventional ECs. These processes enhance charge-storage capacity to boost specific energy, while maintaining the few-second timescale of the charge-discharge response of carbon-based ECs. In this Account, we describe three examples of redox-based deposition of EC-relevant metal oxides (MnO2, FeOx, and RuO2) and discuss their potential deployment in next-generation ECs that use aqueous electrolytes. To extract the maximum pseudocapacitance functionality of metal oxides, one must carefully consider how they are synthesized and subsequently integrated into practical electrode structures. Expressing the metal oxide in a nanoscale form often enhances electrochemical utilization (maximizing specific capacitance) and facilitates high-rate operation for both charge and discharge. The "wiring" of the metal oxide, in terms of both electron and ion transport, when fabricated into a practical electrode architecture, is also a critical design parameter for

  20. Micro- and Nanoscale Heat Transfer in Femtosecond Laser Processing of Metals

    CERN Document Server

    Zhang, Yuwen; Chen, J K

    2015-01-01

    Ultrafast laser material processing has received significant attention due to a growing need for the fabrication of miniaturized devices at micro- and nanoscales. The traditional phenomenological laws, such as Fourier's law of heat conduction, are challenged in the microscale regime and a hyperbolic or dual phase lag model should be employed. During ultrafast laser interaction with metal, the electrons and lattices are not in equilibrium. Various two-temperature models that can be used to describe the nonequilibrium heat transfer are presented. A semi-classical two-step heating model to investigate thermal transport in metals caused by ultrashort laser heating is also presented. The main difference between the semiclassical and the phenomenological two-temperature models is that the former includes the effects of electron drifting, which could result in significantly different electron and lattice temperature response from the latter for higher-intensity and shorter-pulse laser heating. Under higher laser flu...

  1. Role of Interface Charges on High-k Based Poly-Si and Metal Gate Nano-Scale MOSFETs

    Directory of Open Access Journals (Sweden)

    N. Shashank

    2011-01-01

    Full Text Available The characteristics of typical sub-100 nm high K gate dielectrics MOSFET with different gate materials are simulated by two dimensional device simulators (ATLAS and ATHENA. The impact of interface charges on the characteristics of Poly-Si and TiN metal gate MOSFETs are investigated. The simulation results shows that, at high interface charge densities, the devices with Poly-Si gate degrade much compared to metal gate MOSFET structures. Emphasis is given to study the mobility degradation which stands as a major hurdle with the implementation of high-k dielectrics in nano-scale devices. The advantages of using Watt model over other models for the extraction of channel mobility is also clearly explained. The performance of the high-k MOSFET with metal electrode and poly-silicon electrode is also compared for various interface state charges.

  2. A Review of Atomic Layer Deposition for Nanoscale Devices

    Directory of Open Access Journals (Sweden)

    Edy Riyanto

    2012-12-01

    Full Text Available Atomic layer deposition (ALD is a thin film growth technique that utilizes alternating, self-saturation chemical reactions between gaseous precursors to achieve a deposited nanoscale layers. It has recently become a subject of great interest for ultrathin film deposition in many various applications such as microelectronics, photovoltaic, dynamic random access memory (DRAM, and microelectromechanic system (MEMS. By using ALD, the conformability and extreme uniformity of layers can be achieved in low temperature process. It facilitates to be deposited onto the surface in many variety substrates that have low melting temperature. Eventually it has advantages on the contribution to the wider nanodevices.

  3. Plant virus directed fabrication of nanoscale materials and devices

    Science.gov (United States)

    2015-03-26

    TMV1cys assembled on gold-coated silicon wafers (Gerasopoulos et al., 2010). This method utilizes photoresist masks to define sacrificial layers that...microscale SU-8 polymer columns were created and assembled with TMV1cys PVNs as a mimic of the microscale bumps and nanoscale hairs found on lotus leaves...functionalized SiO2 wafers (Mueller et al., 2011) (Fig. 3E). Patterned RNAs containing the OAS were capable of guiding the bottom-up assembly of TMV-like rods

  4. Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale.

    Science.gov (United States)

    Kumar, Naresh; Zoladek-Lemanczyk, Alina; Guilbert, Anne A Y; Su, Weitao; Tuladhar, Sachetan M; Kirchartz, Thomas; Schroeder, Bob C; McCulloch, Iain; Nelson, Jenny; Roy, Debdulal; Castro, Fernando A

    2017-02-23

    Novel optoelectronic devices rely on complex nanomaterial systems where the nanoscale morphology and local chemical composition are critical to performance. However, the lack of analytical techniques that can directly probe these structure-property relationships at the nanoscale presents a major obstacle to device development. In this work, we present a novel method for non-destructive, simultaneous mapping of the morphology, chemical composition and photoelectrical properties with performance. For instance, the direct measurement of fullerene phase purity can distinguish between high purity aggregates that lead to poor performance and lower purity aggregates (fullerene intercalated with polymer) that result in strong photocurrent generation and collection. We show that the reliable determination of the structure-property relationship at the nanoscale can remove ambiguity from macroscopic device data and support the identification of the best routes for device optimisation. The multi-parameter measurement approach demonstrated herein is expected to play a significant role in guiding the rational design of nanomaterial-based optoelectronic devices, by opening a new realm of possibilities for advanced investigation via the combination of nanoscale optical spectroscopy with a whole range of scanning probe microscopy modes.

  5. Plant virus directed fabrication of nanoscale materials and devices.

    Science.gov (United States)

    Culver, James N; Brown, Adam D; Zang, Faheng; Gnerlich, Markus; Gerasopoulos, Konstantinos; Ghodssi, Reza

    2015-05-01

    Bottom-up self-assembly methods in which individual molecular components self-organize to form functional nanoscale patterns are of long-standing interest in the field of materials sciences. Such self-assembly processes are the hallmark of biology where complex macromolecules with defined functions assemble from smaller molecular components. In particular, plant virus-derived nanoparticles (PVNs) have drawn considerable attention for their unique self-assembly architectures and functionalities that can be harnessed to produce new materials for industrial and biomedical applications. In particular, PVNs provide simple systems to model and assemble nanoscale particles of uniform size and shape that can be modified through molecularly defined chemical and genetic alterations. Furthermore, PVNs bring the added potential to "farm" such bio-nanomaterials on an industrial scale, providing a renewable and environmentally sustainable means for the production of nano-materials. This review outlines the fabrication and application of several PVNs for a range of uses that include energy storage, catalysis, and threat detection.

  6. Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

    KAUST Repository

    Kumar, Naresh

    2017-01-12

    Novel optoelectronic devices rely on complex nanomaterial systems where the nanoscale morphology and local chemical composition are critical to performance. However, the lack of analytical techniques that can directly probe these structure-property relationships at the nanoscale presents a major obstacle to device development. In this work, we present a novel method for non-destructive, simultaneous mapping of the morphology, chemical composition and photoelectrical properties with <20 nm spatial resolution by combining plasmonic optical signal enhancement with electrical-mode scanning probe microscopy. We demonstrate that this combined approach offers subsurface sensitivity that can be exploited to provide molecular information with a nanoscale resolution in all three spatial dimensions. By applying the technique to an organic solar cell device, we show that the inferred surface and subsurface composition distribution correlates strongly with the local photocurrent generation and explains macroscopic device performance. For instance, the direct measurement of fullerene phase purity can distinguish between high purity aggregates that lead to poor performance and lower purity aggregates (fullerene intercalated with polymer) that result in strong photocurrent generation and collection. We show that the reliable determination of the structure-property relationship at the nanoscale can remove ambiguity from macroscopic device data and support the identification of the best routes for device optimisation. The multi-parameter measurement approach demonstrated herein is expected to play a significant role in guiding the rational design of nanomaterial-based optoelectronic devices, by opening a new realm of possibilities for advanced investigation via the combination of nanoscale optical spectroscopy with a whole range of scanning probe microscopy modes.

  7. Nanoscale Metallic Iron for Environmental Remediation: Prospects and Limitations

    CERN Document Server

    Noubactep, Chicgoua; Crane, Richard; 10.1007/s11270-011-0951-1

    2012-01-01

    The amendment of the subsurface with nanoscale metallic iron particles (nano-Fe0) has been discussed in the literature as an efficient in situ technology for groundwater remediation. However, the introduction of this technology was controversial and its efficiency has never been univocally established. This unsatisfying situation has motivated this communication whose objective was a comprehensive discussion of the intrinsic reactivity of nano-Fe0 based on the contemporary knowledge on the mechanism of contaminant removal by Fe0 and a mathematical model. It is showed that due to limitations of the mass transfer of nano-Fe0 to contaminants, available concepts cannot explain the success of nano-Fe0 injection for in situ groundwater remediation. It is recommended to test the possibility of introducing nano-Fe0 to initiate the formation of roll-fronts which propagation would induce the reductive transformation of both dissolved and adsorbed contaminants. Within a roll-front, FeII from nano-Fe0 is the reducing age...

  8. Characterization of nano-scale protective oxide films: application on metal chemical mechanical planarization

    OpenAIRE

    Karagöz, Ayşe; Craciun, V.; Başım, Gül Bahar

    2015-01-01

    This study focuses on the characterization of nano-scale metal oxide films for chemical mechanical planarization (CMP) applications. The protective nature of the self-grown metal oxide layers in the CMP slurry environment enable topographic selectivity required for metallization of interconnects. Tungsten was selected as the model metal film to study the formation and characteristics of the metal oxide nano-layers since tungsten CMP is very well-established in conventional semiconductor manuf...

  9. Tantalum oxide nanoscale resistive switching devices: TEM/EELS study (Presentation Recording)

    Science.gov (United States)

    Norris, Kate J.; Zhang, Jiaming; Merced-Grafals, Emmanuelle; Musunuru, Srinitya; Zhang, Max; Samuels, Katy; Yang, Jianhua J.; Kobayashi, Nobuhiko P.

    2015-08-01

    The field of non-volatile memory devices has been boosted by resistive switching, a reversible change in electrical resistance of a dielectric layer through the application of a voltage potential. Tantalum oxide being one of the leading candidates for the dielectric component of resistance switching devices was investigated in this study. 55nm TaOx devices in all states were compared through cross sectional TEM techniques including HRTEM, EELS, and EFTEM and will be discussed in this presentation. Based on the chemical and physical features found in the cross sectioned nanodevices we will discuss the switching mechanism of these nanoscale devices.

  10. Quantum Boltzmann equation solved by Monte Carlo method for nano-scale semiconductor devices simulation

    Institute of Scientific and Technical Information of China (English)

    Du Gang; Liu Xiao-Yan; Han Ru-Qi

    2006-01-01

    A two-dimensional (2D) full band self-consistent ensemble Monte Carlo (MC) method for solving the quantum Boltzmann equation, including collision broadening and quantum potential corrections, is developed to extend the MC method to the study of nano-scale semiconductor devices with obvious quantum mechanical (QM) effects. The quantum effects both in real space and momentum space in nano-scale semiconductor devices can be simulated. The effective mobility in the inversion layer of n and p channel MOSFET is simulated and compared with experimental data to verify this method. With this method 50nm ultra thin body silicon on insulator MOSFET are simulated. Results indicate that this method can be used to simulate the 2D QM effects in semiconductor devices including tunnelling effect.

  11. An open-source platform to study uniaxial stress effects on nanoscale devices

    Science.gov (United States)

    Signorello, G.; Schraff, M.; Zellekens, P.; Drechsler, U.; Bürge, M.; Steinauer, H. R.; Heller, R.; Tschudy, M.; Riel, H.

    2017-05-01

    We present an automatic measurement platform that enables the characterization of nanodevices by electrical transport and optical spectroscopy as a function of the uniaxial stress. We provide insights into and detailed descriptions of the mechanical device, the substrate design and fabrication, and the instrument control software, which is provided under open-source license. The capability of the platform is demonstrated by characterizing the piezo-resistance of an InAs nanowire device using a combination of electrical transport and Raman spectroscopy. The advantages of this measurement platform are highlighted by comparison with state-of-the-art piezo-resistance measurements in InAs nanowires. We envision that the systematic application of this methodology will provide new insights into the physics of nanoscale devices and novel materials for electronics, and thus contribute to the assessment of the potential of strain as a technology booster for nanoscale electronics.

  12. Brain-like associative learning using a nanoscale non-volatile phase change synaptic device array

    Directory of Open Access Journals (Sweden)

    Sukru Burc Eryilmaz

    2014-07-01

    Full Text Available Recent advances in neuroscience together with nanoscale electronic device technology have resulted in huge interests in realizing brain-like computing hardwares using emerging nanoscale memory devices as synaptic elements. Although there has been experimental work that demonstrated the operation of nanoscale synaptic element at the single device level, network level studies have been limited to simulations. In this work, we demonstrate, using experiments, array level associative learning using phase change synaptic devices connected in a grid like configuration similar to the organization of the biological brain. Implementing Hebbian learning with phase change memory cells, the synaptic grid was able to store presented patterns and recall missing patterns in an associative brain-like fashion. We found that the system is robust to device variations, and large variations in cell resistance states can be accommodated by increasing the number of training epochs. We illustrated the tradeoff between variation tolerance of the network and the overall energy consumption, and found that energy consumption is decreased significantly for lower variation tolerance.

  13. Charge transport in nanoscale lateral and vertical organic semiconductor devices

    NARCIS (Netherlands)

    Xu, Bojian

    2017-01-01

    Organic semiconductors have been drawing more and more attention due to their huge potential for low-cost, flexible, printable electronics and spintronics. In this thesis research, we have investigated charge transport in two organic semiconductors, DXP and P3HT, in different device configurations.

  14. Nano-Scale Devices for Frequency-Based Magnetic Biosensing

    Science.gov (United States)

    2017-01-31

    electrically contact a spin torque oscillator on a small rectangular silicon wafer which is mounted above one of the (silver) poles of a projected field...versus those induced by large particles which sit on top of the nanopatterened structure (Sec. IIIC in [3]). 1b. Using magnonic crystals for particle...or perhaps a slightly angled device wafer. DISTRIBUTION A. Approved for public release: distribution unlimited. Fig. 4. (a) Top -down SEM

  15. Detecting Nano-Scale Vibrations in Rotating Devices by Using Advanced Computational Methods

    Directory of Open Access Journals (Sweden)

    Raúl M. del Toro

    2010-05-01

    Full Text Available This paper presents a computational method for detecting vibrations related to eccentricity in ultra precision rotation devices used for nano-scale manufacturing. The vibration is indirectly measured via a frequency domain analysis of the signal from a piezoelectric sensor attached to the stationary component of the rotating device. The algorithm searches for particular harmonic sequences associated with the eccentricity of the device rotation axis. The detected sequence is quantified and serves as input to a regression model that estimates the eccentricity. A case study presents the application of the computational algorithm during precision manufacturing processes.

  16. Electrochromic Metallo-Organic Nanoscale Films: Fabrication, Color Range, and Devices.

    Science.gov (United States)

    Elool Dov, Neta; Shankar, Sreejith; Cohen, Dana; Bendikov, Tatyana; Rechav, Katya; Shimon, Linda J W; Lahav, Michal; van der Boom, Milko E

    2017-08-23

    In this study, we demonstrate a versatile approach for the formation of electrochromic nanoscale assemblies on transparent conductive oxides on both rigid and flexible substrates. Our method is based on the application of alternating spin-coated layers of well-defined metal polypyridyl complexes and a palladium(II) salt to form electrochemically addressable films with a high chromophore density. By varying the central metal ion of the polypyridyl complexes (Os, Ru, and Fe) and their ligands and by mixing these complexes, coatings with a wide range of colors can be achieved. These coatings cover a large area of RGB color space. The coloration intensities of these nanoscale films can be tuned by the number of deposition steps. The materials have very attractive ON/OFF ratios, electrochemical stabilities, and coloration efficiencies. Reversible color-to-colorless and color-to-color transitions were demonstrated, and the films were further integrated into sandwich cells.

  17. Crystal structure engineering for improved performance of emerging nanoscale devices

    Science.gov (United States)

    Chimalgi, Vinay Uday

    Recent advances in growth techniques and increasing number of experimental studies have made nanostructures grown along different crystallographic directions a reality. These new structures could not only benefit the electronic devices used in mainstream information technology but also show great promise for applications in lasers, solid-state lighting, near-field photolithography, free-space quantum cryptography, consumer displays, quantum computation, as well as diagnostic medicine and imaging. However, only few theoretical investigations have been performed on these structures due to the complex nature of the interplay of atomicity, structural fields, polarization, and quantum size-quantization, all strong function of the crystallographic direction. The objective of this work is mainly four-fold: (1) Integrate a computational framework employing a combination of fully atomistic valence force-field molecular mechanics and 20-band sp3s*d5-SO tight-binding based electronic band­structure models, and numerically investigate the effects of internal fields on the electronic and optical properties of zincblende InAs/GaAs quantum dots grown on (100), (110), and (111) orientated substrates. (2) Augment/extend the open source NEMO 3-D bandstructure simulator by incorporating a recently proposed first principles based model to gauge the importance of nonlinear piezoelectricity on the single-particle electronic states and interband optical transitions in emerging In(Ga)N/GaN disk-in-wire LED structures having c-plane and m-plane wurtzite crystal symmetry. (3) Coupling the NEMO 3-D software toolkit with a commercial TCAD simulator to determine the terminal electrical and optical characteristics of InGaN/GaN disk-in-wire LEDs; and (4) Finding an optimum crystallographic device for InGaN/GaN disk-in-wire LEDs to achieve improved internal quantum efficiency (IQE).

  18. Implementation of nanoscale circuits using dual metal gate engineered nanowire MOSFET with high-k dielectrics for low power applications

    Science.gov (United States)

    Charles Pravin, J.; Nirmal, D.; Prajoon, P.; Ajayan, J.

    2016-09-01

    This work covers the impact of dual metal gate engineered Junctionless MOSFET with various high-k dielectric in Nanoscale circuits for low power applications. Due to gate engineering in junctionless MOSFET, graded potential is obtained and results in higher electron velocity of about 31% for HfO2 than SiO2 in the channel region, which in turn improves the carrier transport efficiency. The simulation is done using sentaurus TCAD, ON current, OFF current, ION/IOFF ratio, DIBL, gain, transconductance and transconductance generation factor parameters are analysed. When using HfO2, DIBL shows a reduction of 61.5% over SiO2. The transconductance and transconductance generation factor shows an improvement of 44% and 35% respectively. The gain and output resistance also shows considerable improvement with high-k dielectrics. Using this device, inverter circuit is implemented with different high-k dielectric material and delay have been decreased by 4% with HfO2 when compared to SiO2. In addition, a significant reduction in power dissipation of the inverter circuit is obtained with high-k dielectric Dual Metal Surround Gate Junctionless Transistor than SiO2 based device. From the analysis, it is found that HfO2 will be a better alternative for the future nanoscale device.

  19. SEMICONDUCTOR DEVICES Nanoscale strained-Si MOSFET physics and modeling approaches: a review

    Science.gov (United States)

    Chaudhry, Amit; Roy, J. N.; Joshi, Garima

    2010-10-01

    An attempt has been made to give a detailed review of strained silicon technology. Various device models have been studied that consider the effect of strain on the devices, and comparisons have been drawn. A review of some modeling issues in strained silicon technology has also been outlined. The review indicates that this technology is very much required in nanoscale MOSFETs due to its several potential benefits, and there is a strong need for an analytical model which describes the complete physics of the strain technology.

  20. Bio-Organic Nanotechnology: Using Proteins and Synthetic Polymers for Nanoscale Devices

    Science.gov (United States)

    Molnar, Linda K.; Xu, Ting; Trent, Jonathan D.; Russell, Thomas P.

    2003-01-01

    While the ability of proteins to self-assemble makes them powerful tools in nanotechnology, in biological systems protein-based structures ultimately depend on the context in which they form. We combine the self-assembling properties of synthetic diblock copolymers and proteins to construct intricately ordered, three-dimensional polymer protein structures with the ultimate goal of forming nano-scale devices. This hybrid approach takes advantage of the capabilities of organic polymer chemistry to build ordered structures and the capabilities of genetic engineering to create proteins that are selective for inorganic or organic substrates. Here, microphase-separated block copolymers coupled with genetically engineered heat shock proteins are used to produce nano-scale patterning that maximizes the potential for both increased structural complexity and integrity.

  1. Metal oxide nanostructures as gas sensing devices

    CERN Document Server

    Eranna, G

    2011-01-01

    Metal Oxide Nanostructures as Gas Sensing Devices explores the development of an integrated micro gas sensor that is based on advanced metal oxide nanostructures and is compatible with modern semiconductor fabrication technology. This sensor can then be used to create a compact, low-power, handheld device for analyzing air ambience. The book first covers current gas sensing tools and discusses the necessity for miniaturized sensors. It then focuses on the materials, devices, and techniques used for gas sensing applications, such as resistance and capacitance variations. The author addresses th

  2. Printable nanoscale metal ring arrays via vertically aligned carbon nanotube platforms.

    Science.gov (United States)

    Lee, Sang Ho; Yoon, Seungha; Jeong, Huisu; Han, Mingu; Choi, Sung Mook; Kim, Jong Guk; Park, Ji-Woong; Jung, Gun Young; Cho, Beong Ki; Kim, Won Bae

    2013-11-01

    This paper reports a novel and efficient strategy for fabricating sub-100 nm metal ring arrays using a simple printing process. Vertically aligned carbon nanotubes that are supported by hexagonally ordered channels of alumina matrices are used as a stamp to print nanoscale ring patterns, which is a very unique stamping platform that has never been reported. Using this strategy, uniform nanoring patterns of various metals can be directly printed onto a wide range of substrate surfaces under ambient conditions. Significantly, the size and interval of the printed nanorings can be systematically tuned by controlling the ring-shaped tip dimensions of the pristine stamps. An advanced example of these printable nanoscale metal ring arrays is explicitly embodied in this work by investigation of the plasmon resonances of metal nanorings with different sizes and intervals.

  3. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films.

    Science.gov (United States)

    Burgess, J A J; Holt, C M B; Luber, E J; Fortin, D C; Popowich, G; Zahiri, B; Concepcion, P; Mitlin, D; Freeman, M R

    2016-08-08

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100-xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections.

  4. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    Science.gov (United States)

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-01-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100−xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections. PMID:27498698

  5. Recent applications of liquid metals featuring nanoscale surface oxides

    Science.gov (United States)

    Neumann, Taylor V.; Dickey, Michael D.

    2016-05-01

    This proceeding describes recent efforts from our group to control the shape and actuation of liquid metal. The liquid metal is an alloy of gallium and indium which is non-toxic, has negligible vapor pressure, and develops a thin, passivating surface oxide layer. The surface oxide allows the liquid metal to be patterned and shaped into structures that do not minimize interfacial energy. The surface oxide can be selectively removed by changes in pH or by applying a voltage. The surface oxide allows the liquid metal to be 3D printed to form free-standing structures. It also allows for the liquid metal to be injected into microfluidic channels and to maintain its shape within the channels. The selective removal of the oxide results in drastic changes in surface tension that can be used to control the flow behavior of the liquid metal. The metal can also wet thin, solid films of metal that accelerates droplets of the liquid along the metal traces .Here we discuss the properties and applications of liquid metal to make soft, reconfigurable electronics.

  6. Nanoscale size effects in crystallization of metallic glass nanorods.

    Science.gov (United States)

    Sohn, Sungwoo; Jung, Yeonwoong; Xie, Yujun; Osuji, Chinedum; Schroers, Jan; Cha, Judy J

    2015-09-01

    Atomistic understanding of crystallization in solids is incomplete due to the lack of appropriate materials and direct experimental tools. Metallic glasses possess simple metallic bonds and slow crystallization kinetics, making them suitable to study crystallization. Here, we investigate crystallization of metallic glass-forming liquids by in-situ heating metallic glass nanorods inside a transmission electron microscope. We unveil that the crystallization kinetics is affected by the nanorod diameter. With decreasing diameters, crystallization temperature decreases initially, exhibiting a minimum at a certain diameter, and then rapidly increases below that. This unusual crystallization kinetics is a consequence of multiple competing factors: increase in apparent viscosity, reduced nucleation probability and enhanced heterogeneous nucleation. The first two are verified by slowed grain growth and scatter in crystallization temperature with decreasing diameters. Our findings provide insight into relevant length scales in crystallization of supercooled metallic glasses, thus offering accurate processing conditions for predictable metallic glass nanomolding.

  7. Low-temperature sintering of nanoscale silver paste for semiconductor device interconnection

    Science.gov (United States)

    Bai, Guofeng

    This research has developed a lead-free semiconductor device interconnect technology by studying the processing-microstructure-property relationships of low-temperature sintering of nanoscale silver pastes. The nanoscale silver pastes have been formulated by adding organic components (dispersant, binder and thinner) into nano-silver particles. The selected organic components have the nano-particle polymeric stabilization, paste processing quality adjustment, and non-densifying diffusion retarding functions and thus help the pastes sinter to ˜80% bulk density at temperatures no more than 300°C. It has been found that the low-temperature sintered silver has better electrical, thermal and overall thermomechanical properties compared with the existing semiconductor device interconnecting materials such as solder alloys and conductive epoxies. After solving the organic burnout problems associated with the covered sintering, a lead-free semiconductor device interconnect technology has been designed to be compatible with the existing surface-mounting techniques with potentially low-cost. It has been found that the low-temperature sintered silver joints have high electrical, thermal, and mechanical performance. The reliability of the silver joints has also been studied by the 50-250°C thermal cycling experiment. Finally, the bonging strength drop of the silver joints has been suggested to be ductile fracture in the silver joints as micro-voids nucleated at microscale grain boundaries during the temperature cycling. The low-temperature silver sintering technology has enabled some benchmark packaging concepts and substantial advantages in future applications.

  8. Striped nanoscale phase separation at the metal-insulator transition of heteroepitaxial nickelates

    Science.gov (United States)

    Mattoni, G.; Zubko, P.; Maccherozzi, F.; van der Torren, A. J. H.; Boltje, D. B.; Hadjimichael, M.; Manca, N.; Catalano, S.; Gibert, M.; Liu, Y.; Aarts, J.; Triscone, J.-M.; Dhesi, S. S.; Caviglia, A. D.

    2016-11-01

    Nucleation processes of mixed-phase states are an intrinsic characteristic of first-order phase transitions, typically related to local symmetry breaking. Direct observation of emerging mixed-phase regions in materials showing a first-order metal-insulator transition (MIT) offers unique opportunities to uncover their driving mechanism. Using photoemission electron microscopy, we image the nanoscale formation and growth of insulating domains across the temperature-driven MIT in NdNiO3 epitaxial thin films. Heteroepitaxy is found to strongly determine the nanoscale nature of the phase transition, inducing preferential formation of striped domains along the terraces of atomically flat stepped surfaces. We show that the distribution of transition temperatures is a local property, set by surface morphology and stable across multiple temperature cycles. Our data provide new insights into the MIT of heteroepitaxial nickelates and point to a rich, nanoscale phenomenology in this strongly correlated material.

  9. Nanoscale electrodeposition of low-dimensional metal phases and clusters.

    Science.gov (United States)

    Staikov, Georgi

    2016-08-01

    The present status of the problem of electrochemical formation of low-dimensional metal phases is reviewed. The progress in this field achieved in the last two decades is discussed on the basis of experimental results obtained in selected electrochemical systems with well defined single crystal substrates. The influence of crystallographic orientation and surface inhomogeneities of foreign substrates on the mechanism of formation and the atomic structure of two-dimensional (2D) metal phases in the underpotential deposition range is considered. The localized electrodeposition of metal nanoclusters on solid state surfaces applying the STM-tip as a nanoelectrode is demonstrated.

  10. Nanoscale electrodeposition of low-dimensional metal phases and clusters

    Science.gov (United States)

    Staikov, Georgi

    2016-07-01

    The present status of the problem of electrochemical formation of low-dimensional metal phases is reviewed. The progress in this field achieved in the last two decades is discussed on the basis of experimental results obtained in selected electrochemical systems with well defined single crystal substrates. The influence of crystallographic orientation and surface inhomogeneities of foreign substrates on the mechanism of formation and the atomic structure of two-dimensional (2D) metal phases in the underpotential deposition range is considered. The localized electrodeposition of metal nanoclusters on solid state surfaces applying the STM-tip as a nanoelectrode is demonstrated.

  11. Spin transport in metal and oxide devices at the nanoscale

    NARCIS (Netherlands)

    Parui, Subir; Rana, Kumari Gaurav; Banerjee, Tamalika

    2012-01-01

    Here we discuss a non-destructive technique that characterizes spin and charge transport at the nanometer scale, across buried layers and interfaces, in magnetic memory elements as used in spin transfer torque based Magnetic Random Access Memory (STT-MRAM). While probing in the

  12. Maximum efficiency of state-space models of nanoscale energy conversion devices.

    Science.gov (United States)

    Einax, Mario; Nitzan, Abraham

    2016-07-07

    The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage.

  13. The non-equilibrium Green's function method for nanoscale device simulation

    CERN Document Server

    Pourfath, Mahdi

    2014-01-01

    For modeling the transport of carriers in nanoscale devices, a Green-function formalism is the most accurate approach. Due to the complexity of the formalism, one should have a deep understanding of the underlying principles and use smart approximations and numerical methods for solving the kinetic equations at a reasonable computational time. In this book the required concepts from quantum and statistical mechanics and numerical methods for calculating Green functions are presented. The Green function is studied in detail for systems both under equilibrium and under nonequilibrium conditions. Because the formalism enables rigorous modeling of different scattering mechanisms in terms of self-energies, but an exact evaluation of self-energies for realistic systems is not possible, their approximation and inclusion in the quantum kinetic equations of the Green functions are elaborated. All the elements of the kinetic equations, which are the device Hamiltonian, contact self-energies, and scattering self-energie...

  14. Maximum efficiency of state-space models of nanoscale energy conversion devices

    Science.gov (United States)

    Einax, Mario; Nitzan, Abraham

    2016-07-01

    The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage.

  15. Micro- and nanoscale devices for the investigation of epigenetics and chromatin dynamics

    Science.gov (United States)

    Aguilar, Carlos A.; Craighead, Harold G.

    2013-10-01

    Deoxyribonucleic acid (DNA) is the blueprint on which life is based and transmitted, but the way in which chromatin -- a dynamic complex of nucleic acids and proteins -- is packaged and behaves in the cellular nucleus has only begun to be investigated. Epigenetic modifications sit 'on top of' the genome and affect how DNA is compacted into chromatin and transcribed into ribonucleic acid (RNA). The packaging and modifications around the genome have been shown to exert significant influence on cellular behaviour and, in turn, human development and disease. However, conventional techniques for studying epigenetic or conformational modifications of chromosomes have inherent limitations and, therefore, new methods based on micro- and nanoscale devices have been sought. Here, we review the development of these devices and explore their use in the study of DNA modifications, chromatin modifications and higher-order chromatin structures.

  16. Energy Conversion Application of Chemicurrents Induced in Metal-Semiconductor Nanostructured Devices

    Science.gov (United States)

    Dasari, Suhas Kiran

    Hydrogen is one the most attractive and suitable energy systems for generation of power in the future with high efficiencies and renewable properties. Nanoscale materials, because of their surface and physical properties are the promising candidates for the development of high performance energy conversion devices, essential components to ensure the efficient operation of the infrastructure and to facilitate the wide spread implementation of hydrogen technologies. This work realizes the use of solid state energy conversion concept to develop metal-semiconductor, metal-oxide architecture devices for electrolyte free conversion of chemical energy to electrical energy by hydrogen oxidation process. This investigation addresses the synthesis of these nanostructure devices by selection of suitable system material combinations, electrical and surface morphological characterization leading to the successful implementation in generation of chemicurrents. Also, the hydrogen oxidation process on each nanostructure device is elucidated with the help of corresponding mechanisms and the performance of each system developed was evaluated based on the resulting output efficiency. The two systems (metal-semiconductor and metal-oxide) realized, showed excellent chemical to electrical energy conversion abilities. Compared to metal-semiconductor nanostructure devices, metal-oxide systems exhibited better energy conversion abilities for indefinitely long duration of time at room temperature. The electron yield observed in considered metal-oxide systems can be sufficient for their use in practical applications. A continued realization of these metal-oxide systems with different material combinations would lead to more ecologically friendly and sustainable energy economics.

  17. Sonochemical Synthesis of Photoluminescent Nanoscale Eu(III-Containing Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Cheng-an TAO

    2015-11-01

    Full Text Available Nanoscale lanthanide-containing metal-organic frameworks (MOFs have more and more interest due to their great properties and potential applications, but how to construct them easily is still challenging. Here, we present a facile and rapid synthesis of Eu(III-containing Nanoscale MOF (denoted as NMOF under ultrasonic irradiation. The effect of the ratio and the addition order of metal ions and linkers on the morphology and size of MOFs was investigated. It is found that both of the ratio and the addition order can affect the morphology and size of 1.4-benzenedicarboxylic acid(H2BDC -based MOFs, but they show no evident influence on that of H2aBDC-based MOFs. The former exhibit typical emission bands of Eu(III ions, while the latter only show the photoluminescent properties of ligands.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9695

  18. Sonochemical Synthesis of Photoluminescent Nanoscale Eu(III-Containing Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Cheng-an TAO

    2015-11-01

    Full Text Available Nanoscale lanthanide-containing metal-organic frameworks (MOFs have more and more interest due to their great properties and potential applications, but how to construct them easily is still challenging. Here, we present a facile and rapid synthesis of Eu(III-containing Nanoscale MOF (denoted as NMOF under ultrasonic irradiation. The effect of the ratio and the addition order of metal ions and linkers on the morphology and size of MOFs was investigated. It is found that both of the ratio and the addition order can affect the morphology and size of 1.4-benzenedicarboxylic acid(H2BDC -based MOFs, but they show no evident influence on that of H2aBDC-based MOFs. The former exhibit typical emission bands of Eu(III ions, while the latter only show the photoluminescent properties of ligands.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9695

  19. Novel Metal-Matrix Composites With Integrally-Bound Nanoscale Carbon

    Science.gov (United States)

    2012-06-01

    identical. 7.2 Aluminum Alloy 7075 We evaluated the tensile properties of AA7075 containing 0.84 wt%, 2.2 wt% and 4 wt% nanocarbon. The material ...Novel Metal-Matrix Composites with Integrally-Bound Nanoscale Carbon David R. Forrest*, Iwona Jasiuk**, CAPT Lloyd Brown***, Peter Joyce***, Azzam...test conditions. In aluminum, we observed a significant increase in electrical conductivity with nanocarbon, from 47 to 67% IACS. These materials

  20. Ultrahigh-speed rotating nanoelectromechanical system devices assembled from nanoscale building blocks

    Science.gov (United States)

    Kim, Kwanoh; Xu, Xiaobin; Guo, Jianhe; Fan, D. L.

    2014-04-01

    The development of rotary nanomotors is crucial for advancing nanoelectromechanical system technology. In this work, we report design, assembly and rotation of ordered arrays of nanomotors. The nanomotors are bottom-up assembled from nanoscale building blocks with nanowires as rotors, patterned nanomagnets as bearings and quadrupole microelectrodes as stators. Arrays of nanomotors rotate with controlled angle, speed (over 18,000 r.p.m.), and chirality by electric fields. Using analytical modelling, we reveal the fundamental nanoscale electrical, mechanical and magnetic interactions in the nanomotor system, which excellently agrees with experimental results and provides critical understanding for designing metallic nanoelectromechanical systems. The nanomotors can be continuously rotated for 15 h over 240,000 cycles. They are applied for controlled biochemical release and demonstrate releasing rate of biochemicals on nanoparticles that can be precisely tuned by mechanical rotations. The innovations reported in this research, from concept, design and actuation to application, are relevant to nanoelectromechanical system, nanomedicine, microfluidics and lab-on-a-chip architectures.

  1. Invited Review Nanoscale devices fabricated by dynamic ploughing with an atomic force microscope

    Science.gov (United States)

    Kunze, Ulrich

    2002-01-01

    A review is given on the dynamic ploughing technique and its application on the fabrication of nanoscale semiconductor structures. The vibrating tip of an atomic force microscope is used to dynamically plough furrows into a polymer layer of a few nm thickness on top of the semiconductor surface. Wet-chemical etching transfers the desired line pattern. The resulting grooves of 50-100 nm width form an arrangement of barriers in the electron layer of a conventional modulation-doped GaAs/AlGaAs heterostructure. A new type of heterostructure with a compensating p-type doped cap layer shows an electron enhancement if the cap layer is selectively removed. Etching a groove in these structures enables one to induce a one-dimensional electron system. Both types of structures are used to fabricate various ballistic quantum devices and Coulomb-blockade structures.

  2. Novel plasmonic probes and smart superhydrophobic devices, New tools for forthcoming spectroscopies at the nanoscale

    KAUST Repository

    Giugni, Andrea

    2014-08-11

    In this work we review novel strategies and new physical effects to achieve compositional and structural recognition at single molecule level. This chapter is divided in two main parts. The first one introduces the strategies currently adopted to investigate matter at few molecules level. Exploiting the capability of surface plasmon polaritons to deliver optical excitation at nanoscale, we introduce a technique relying on a new transport phenomenon with chemical sensitivity and nanometer spatial resolution. The second part describes how micro and nanostructured superhydrofobic textures can concentrate and localize a small number of molecules into a well-defined region, even when only an extremely diluted solution is available. Several applications of these devices as micro- and nano-systems for high-resolution imaging techniques, cell cultures and tissue engineering applications are also discussed.

  3. Enhancement of high-TC superconducting thin film devices by nanoscale polishing

    Science.gov (United States)

    Michalowski, P.; Shapoval, T.; Meier, D.; Katzer, C.; Schmidl, F.; Schultz, L.; Seidel, P.

    2012-11-01

    The effects of mechanical nanoscale polishing on the superconducting parameters of YBa2Cu3O7-δ (YBCO) thin films and bi-crystal grain boundary Josephson junctions have been investigated. We prepared samples with additional gold nanocrystallites in the YBCO film. As they are distributed throughout the whole YBCO film, they provide a low-resistance ohmic contact even if parts of the film are removed. Polishing was performed either before or after the patterning and did not change the properties of the grain boundary. However, nanopolishing reduces the film roughness in a significant way, which makes it an indispensable tool for the preparation of integrated superconducting circuits. We also succeeded in tuning the IC and RN of the Josephson junctions of direct current superconducting quantum interference devices (dc-SQUIDs) by systematically reducing the film thickness, which opens up new possibilities in the application of magnetic field sensors.

  4. Investigating Deformation and Failure Mechanisms in Nanoscale Multilayer Metallic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Zbib, Hussein M. [Washington State Univ., Pullman, WA (United States); Bahr, David F. [Purdue Univ., West Lafayette, IN (United States)

    2014-10-22

    Over the history of materials science there are many examples of materials discoveries that have made superlative materials; the strongest, lightest, or toughest material is almost always a goal when we invent new materials. However, often these have been a result of enormous trial and error approaches. A new methodology, one in which researchers design, from the atoms up, new ultra-strong materials for use in energy applications, is taking hold within the science and engineering community. This project focused on one particular new classification of materials; nanolaminate metallic composites. These materials, where two metallic materials are intimately bonded and layered over and over to form sheets or coatings, have been shown over the past decade to reach strengths over 10 times that of their constituents. However, they are not yet widely used in part because while extremely strong (they don’t permanently bend), they are also not particularly tough (they break relatively easily when notched). Our program took a coupled approach to investigating new materials systems within the laminate field. We used computational materials science to explore ways to institute new deformation mechanisms that occurred when a tri-layer, rather than the more common bi-layer system was created. Our predictions suggested that copper-nickel or copper-niobium composites (two very common bi-layer systems) with layer thicknesses on the order of 20 nm and then layered 100’s of times, would be less tough than a copper-nickel-niobium metallic composite of similar thicknesses. In particular, a particular mode of permanent deformation, cross-slip, could be activated only in the tri-layer system; the crystal structure of the other bi-layers would prohibit this particular mode of deformation. We then experimentally validated this predication using a wide range of tools. We utilized a DOE user facility, the Center for Integrated Nanotechnology (CINT), to fabricate, for the first time, these

  5. Different shades of oxide: from nanoscale wetting mechanisms to contact printing of gallium-based liquid metals.

    Science.gov (United States)

    Doudrick, Kyle; Liu, Shanliangzi; Mutunga, Eva M; Klein, Kate L; Damle, Viraj; Varanasi, Kripa K; Rykaczewski, Konrad

    2014-06-17

    Gallium-based liquid metals are of interest for a variety of applications including flexible electronics, soft robotics, and biomedical devices. Still, nano- to microscale device fabrication with these materials is challenging because, despite having surface tension 10 times higher than water, they strongly adhere to a majority of substrates. This unusually high adhesion is attributed to the formation of a thin oxide shell; however, its role in the adhesion process has not yet been established. In this work, we demonstrate that, dependent on dynamics of formation and resulting morphology of the liquid metal-substrate interface, GaInSn adhesion can occur in two modes. The first mode occurs when the oxide shell is not ruptured as it makes contact with the substrate. Because of the nanoscale topology of the oxide surface, this mode results in minimal adhesion between the liquid metal and most solids, regardless of substrate's surface energy or texture. In the second mode, the formation of the GaInSn-substrate interface involves rupturing of the original oxide skin and formation of a composite interface that includes contact between the substrate and pieces of old oxide, bare liquid metal, and new oxide. We demonstrate that in this latter mode GaInSn adhesion is dominated by the intimate contact between new oxide and substrate. We also show that by varying the pinned contact line length using varied degrees of surface texturing, the adhesion of GaInSn in this mode can be either decreased or increased. Lastly, we demonstrate how these two adhesion modes limit microcontact printing of GaInSn patterns but can be exploited to repeatedly print individual sub-200 nm liquid metal drops.

  6. Predictive atomistic simulations of electronic properties of realistic nanoscale devices: A multiscale modeling approach

    Science.gov (United States)

    Vedula, Ravi Pramod Kumar

    Scaling of CMOS towards its ultimate limits, where quantum effects and atomistic variability due to fabrication, along with recent emphasis on heterogeneous integration of non-digital devices for increasing the functional diversification presents us with fundamentally new challenges. A comprehensive understanding of design and operation of these nanoscale transistors, and other electronic devices like RF-MEMS, requires an insight into their electronic and mechanical properties that are strongly influenced by underlying atomic structure. Hence, continuum descriptions of materials and use of empirical models at these scales become questionable. This increase in complexity of electronic devices necessitates an understanding at a more fundamental level to accurately predict the performance and reliability of these devices. The objective of this thesis is to outline the application of multiscale predictive modeling methods, ranging from atoms to devices, for addressing these challenges. This capability is demonstrated using two examples: characterization of (i) dielectric charging in RF-MEMS, and (ii) transport properties of Ge-nanofins. For characterizing the dielectric charging phenomenon, a continuum dielectric charging model, augmented by first principles informed trap distributions, is used to predict current transient measurements across a broad range of voltages and temperatures. These simulations demonstrate using ab initio informed model not only reduces the empiricism (number of adjustable parameters) in the model but also leads to a more accurate model over a broad range of operating conditions, and enable the precise determination of additional material parameters. These atomistic calculations also provide detailed information about the nature of charge traps and their trapping mechanisms that are not accessible experimentally; such information could prove invaluable in defect engineering. The second problem addresses the effect of the in-homogeneous strain

  7. Nanoscale metals and semiconductors for the storage of solar energy in chemical bonds

    Science.gov (United States)

    Manthiram, Karthish

    The transduction of electrical energy into chemical bonds represents one potential strategy for storing energy derived from intermittent sources such as solar and wind. Driving the electrochemical reduction of carbon dioxide using light requires (1) developing light absorbers which convert photons into electron-hole pairs and (2) catalysts which utilize these electrons and holes to reduce carbon dioxide and oxidize water, respectively. For both the light absorbers and catalysts, the use of nanoscale particles is advantageous, as charge transport length scales are minimized in the case of nanoscale light absorbers and catalytic surface-area-to-volume ratio is maximized for nanoscale catalysts. In many cases, although semiconductors and metals in the form of thin films and foils are increasingly well-characterized as photoabsorbers and electrocatalysts for carbon dioxide reduction, respectively, the properties of their nanoscale counterparts remain poorly understood. This dissertation explores the nature of the light absorption mode of non-stoichiometric semiconductors which are utilized as light absorbers and the development of catalysts with enhanced stability, activity, and selectivity for carbon dioxide reduction. Chapter 1 provides an overview of the state of development of methods of transducing the energy of photons into chemical bonds. Chapters 2 and 3 investigate the development of stable, active, and selective catalysts for the electrochemical reduction of carbon dioxide. Chapter 2 examines how copper nanoparticles have enhanced activities and selectivities for methanation compared to copper foils. Chapter 3 focuses on the development of strategies to stabilize high-surface-area catalysts to prevent surface area loss during electrochemical carbon dioxide reduction. Chapters 4 and 5 entail a fundamental understanding of the light absorption mode of nanoscale photoabsorbers used in both photoelectrochemical cells and in photovoltaics. Chapter 4 focuses on the

  8. Impact of biogenic nanoscale metals Fe, Cu, Zn and Se on reproductive LV chickens

    Science.gov (United States)

    Khiem Nguyen, Quy; Dieu Nguyen, Duy; Kien Nguyen, Van; Thinh Nguyen, Khac; Chau Nguyen, Hoai; Tin Tran, Xuan; Nguyen, Huu Cuong; Tien Phung, Duc

    2015-09-01

    Using biogenic nanoscale metals (Fe, Cu, ZnO, Se) to supplement into diet premix of reproductive LV (a Vietnamese Luong Phuong chicken breed) chickens resulted in certain improvement of poultry farming. The experimental data obtained showed that the farming indices depend mainly on the quantity of nanocrystalline metals which replaced the inorganic mineral component in the feed premix. All four experimental groups with different quantities of the replacement nano component grew and developed normally with livability reaching 91 to 94%, hen’s bodyweight at 38 weeks of age and egg weight ranged from 2.53-2.60 kg/hen and 50.86-51.55 g/egg, respectively. All these farming indices together with laying rate, egg productivity and chick hatchability peaked at group 5 with 25% of nanoscale metals compared to the standard inorganic mineral supplement, while feed consumption was lowest. The results also confirmed that nanocrystalline metals Fe, Cu, ZnO and Se supplemented to chicken feed were able to decrease inorganic minerals in the diet premixes at least four times, allowing animals to more effectively absorb feed minerals, consequently decreasing environmental pollution risks.

  9. Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

    Energy Technology Data Exchange (ETDEWEB)

    Granata, Carmine, E-mail: carmine.granata@cnr.it; Vettoliere, Antonio

    2016-02-19

    The magnetic sensing at nanoscale level is a promising and interesting research topic of nanoscience. Indeed, magnetic imaging is a powerful tool for probing biological, chemical and physical systems. The study of small spin cluster, like magnetic molecules and nanoparticles, single electron, cold atom clouds, is one of the most stimulating challenges of applied and basic research of the next years. In particular, the magnetic nanoparticle investigation plays a fundamental role for the modern material science and its relative technological applications like ferrofluids, magnetic refrigeration and biomedical applications, including drug delivery, hyper-thermia cancer treatment and magnetic resonance imaging contrast-agent. Actually, one of the most ambitious goals of the high sensitivity magnetometry is the detection of elementary magnetic moment or spin. In this framework, several efforts have been devoted to the development of a high sensitivity magnetic nanosensor pushing sensing capability to the individual spin level. Among the different magnetic sensors, Superconducting QUantum Interference Devices (SQUIDs) exhibit an ultra high sensitivity and are widely employed in numerous applications. Basically, a SQUID consists of a superconducting ring (sensitive area) interrupted by two Josephson junctions. In the recent years, it has been proved that the magnetic response of nano-objects can be effectively measured by using a SQUID with a very small sensitive area (nanoSQUID). In fact, the sensor noise, expressed in terms of the elementary magnetic moment (spin or Bohr magneton), is linearly dependent on the SQUID loop side length. For this reason, SQUIDs have been progressively miniaturized in order to improve the sensitivity up to few spin per unit of bandwidth. With respect to other techniques, nanoSQUIDs offer the advantage of direct measurement of magnetization changes in small spin systems. In this review, we focus on nanoSQUIDs and its applications. In

  10. Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

    Science.gov (United States)

    Granata, Carmine; Vettoliere, Antonio

    2016-02-01

    The magnetic sensing at nanoscale level is a promising and interesting research topic of nanoscience. Indeed, magnetic imaging is a powerful tool for probing biological, chemical and physical systems. The study of small spin cluster, like magnetic molecules and nanoparticles, single electron, cold atom clouds, is one of the most stimulating challenges of applied and basic research of the next years. In particular, the magnetic nanoparticle investigation plays a fundamental role for the modern material science and its relative technological applications like ferrofluids, magnetic refrigeration and biomedical applications, including drug delivery, hyper-thermia cancer treatment and magnetic resonance imaging contrast-agent. Actually, one of the most ambitious goals of the high sensitivity magnetometry is the detection of elementary magnetic moment or spin. In this framework, several efforts have been devoted to the development of a high sensitivity magnetic nanosensor pushing sensing capability to the individual spin level. Among the different magnetic sensors, Superconducting QUantum Interference Devices (SQUIDs) exhibit an ultra high sensitivity and are widely employed in numerous applications. Basically, a SQUID consists of a superconducting ring (sensitive area) interrupted by two Josephson junctions. In the recent years, it has been proved that the magnetic response of nano-objects can be effectively measured by using a SQUID with a very small sensitive area (nanoSQUID). In fact, the sensor noise, expressed in terms of the elementary magnetic moment (spin or Bohr magneton), is linearly dependent on the SQUID loop side length. For this reason, SQUIDs have been progressively miniaturized in order to improve the sensitivity up to few spin per unit of bandwidth. With respect to other techniques, nanoSQUIDs offer the advantage of direct measurement of magnetization changes in small spin systems. In this review, we focus on nanoSQUIDs and its applications. In

  11. Nanoscience and technology: An interdisciplinary initiative, self-assembling nanoscale quantum devices

    Energy Technology Data Exchange (ETDEWEB)

    Doolen, G.; Smith, D.; Mineev, M. [and others

    1996-10-01

    This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Our objective is to develop the devices, interconnection technologies, and self-assembling systems required for quantum-based information processing that permit ultra-dense integrated circuits and that allow continuation of the on-going silicon VLSI miniaturization process. That process is facing increasing difficulties related to switch performance, heat dissipation, interconnect failure, quantum effect complications, and rapidly escalating manufacturing costs. Our approach is intended to address these concerns and consists of the development of highly parallel stochastic computers utilizing quantum components and self-assembly methods; the development of self-assembling monolayers for use as resists and memory devices; and research on approaches to molecular self-assembly of the precursors to molecular transistors. The work will provide confirmation of principles, is intended to provide near-term results of potential relevance to the commercial sector, and has a range of applications that include high performance computing, biotechnology, and nanoscale chemistry.

  12. Development of a Cryostat to Characterize Nano-scale Superconducting Quantum Interference Devices

    Science.gov (United States)

    Longo, Mathew; Matheny, Matthew; Knudsen, Jasmine

    2016-03-01

    We have designed and constructed a low-noise vacuum cryostat to be used for the characterization of nano-scale superconducting quantum interference devices (SQUIDs). Such devices are very sensitive to magnetic fields and can measure changes in flux on the order of a single electron magnetic moment. As a part of the design process, we calculated the separation required between the cryogenic preamplifier and superconducting magnet, including a high-permeability magnetic shield, using a finite-element model of the apparatus. The cryostat comprises a vacuum cross at room temperature for filtered DC and shielded RF electrical connections, a thin-wall stainless steel support tube, a taper-sealed cryogenic vacuum can, and internal mechanical support and wiring for the nanoSQUID. The Dewar is modified with a room-temperature flange with a sliding seal for the cryostat. The flange supports the superconducting 3 Tesla magnet and thermometry wiring. Upon completion of the cryostat fabrication and Dewar modifications, operation of the nanoSQUIDs as transported from our collaborator's laboratory in Israel will be confirmed, as the lead forming the SQUID is sensitive to oxidation and the SQUIDs must be shipped in a vacuum container. After operation of the nanoSQUIDs is confirmed, the primary work of characterizing their high-speed properties will begin. This will include looking at the measurement of relaxation oscillations at high bandwidth in comparison to the theoretical predictions of the current model.

  13. Sub-15-nm patterning of asymmetric metal electrodes and devices by adhesion lithography

    KAUST Repository

    Beesley, David J.

    2014-05-27

    Coplanar electrodes formed from asymmetric metals separated on the nanometre length scale are essential elements of nanoscale photonic and electronic devices. Existing fabrication methods typically involve electron-beam lithography - a technique that enables high fidelity patterning but suffers from significant limitations in terms of low throughput, poor scalability to large areas and restrictive choice of substrate and electrode materials. Here, we describe a versatile method for the rapid fabrication of asymmetric nanogap electrodes that exploits the ability of selected self-assembled monolayers to attach conformally to a prepatterned metal layer and thereby weaken adhesion to a subsequently deposited metal film. The method may be carried out under ambient conditions using simple equipment and a minimum of processing steps, enabling the rapid fabrication of nanogap electrodes and optoelectronic devices with aspect ratios in excess of 100,000.2014 Macmillan Publishers Limited. All rights reserved.

  14. Electronic processes in molecular dynamics simulations of nanoscale metal tips under electric fields

    CERN Document Server

    Parviainen, S; Djurabekova, F; Timko, H

    2011-01-01

    Electronic effects play a crucial role in the temperature evolution of metal parts which have electric currents running through them. The increase in temperature due to resistive heating can cause the melting of metal nanoscale wires creating damage in electric circuits. Likewise, electric currents are also present in sharp features on metal surfaces exposed to high electric fields. The destruction of such tips can lead to vacuum arcs, supplying the neutral species to build up plasma over the surface. To follow the temperature evolution caused by electric currents in such a tip, we developed a new model, based on an existing molecular dynamics code, to include resistive heating and electronic thermal conduction. The results given by the new simulation model are in good agreement with analytical predictions. (C) 2011 Published by Elsevier B.V.

  15. Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

    Science.gov (United States)

    Feng, S. D.; Jiao, W.; Jing, Q.; Qi, L.; Pan, S. P.; Li, G.; Ma, M. Z.; Wang, W. H.; Liu, R. P.

    2016-11-01

    Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously.

  16. Current Progress of Mechanical Properties of Metals with Nano-scale Twins

    Institute of Scientific and Technical Information of China (English)

    Lei LU

    2008-01-01

    Focus on face-centered cubic (fcc) metals with nano-scale twins lamellar structure, this paper presents a brief overview of the recent progress made in improving mechanical properties, including strength, ductility, work hardening, strain rate sensitivities, and in mechanistically understanding the underling deformation mechanisms. Significant developments have been achieved in nano-twinned fcc metals with a combination of high strength and considerable ductility at the same time, enhanced work hardening ability and enhanced rate sensitivity. The findings elucidate the role of interactions between dislocations and twin boundaries (TBs) and their contribution to the origin of outstanding properties. The computer simulation analysis accounts for high plastic anisotropy and rate sensitivity anisotropy by treating TBs as internal interfaces and allowing special slip geometry arrangements that involve soft and hard modes of deformation. Parallel to the novel mechanical behaviors of the nano-twinned materials, the investigation and developments of nanocrystalline materials are also discussed in this overview for comparing the contribution of grain boundaries/TBs and grain size/twin lamellar spacing to the properties. The recent advances in the experimental and computational studies of plastic deformation of the fcc metals with nano-scale twin lamellar structures provide insights into the possible means of optimizing comprehensive mechanical properties through interfacial engineering.

  17. The influence of nanoscale morphology on the resistivity of cluster-assembled nanostructured metallic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Barborini, E; Bertolini, G; Repetto, P; Leccardi, M; Vinati, S [Tethis srl, via Franco Russoli 3, 20143 Milano (Italy); Corbelli, G; Milani, P, E-mail: emanuele.barborini@tethis-lab.co, E-mail: pmilani@mi.infn.i [CIMAINA and Dipartimento di Fisica, Universita di Milano, via Celoria 16, 20133 Milano (Italy)

    2010-07-15

    We have studied in situ the evolution of the electrical resistivity of Fe, Pd, Nb, W and Mo cluster-assembled films during their growth by supersonic cluster beam deposition. We observed resistivity of cluster-assembled films several orders of magnitude larger than the bulk, as well as an increase in resistivity by increasing the film thickness in contrast to what was observed for atom-assembled metallic films. This suggests that the nanoscale morphological features typical of ballistic films growth, such as the minimal cluster-cluster interconnection and the evolution of surface roughness with thickness, are responsible for the observed behaviour.

  18. Numerical analysis of an optical nanoscale particles trapping device based on a slotted nanobeam cavity

    Science.gov (United States)

    Zhang, Senlin; Yong, Zhengdong; Shi, Yaocheng; He, Sailing

    2016-01-01

    A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 107 while maintaining a small mode volume of 0.067(λ/nwater)3. Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kBT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future. PMID:27786248

  19. Numerical analysis of an optical nanoscale particles trapping device based on a slotted nanobeam cavity

    Science.gov (United States)

    Zhang, Senlin; Yong, Zhengdong; Shi, Yaocheng; He, Sailing

    2016-10-01

    A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 107 while maintaining a small mode volume of 0.067(λ/nwater)3. Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kBT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future.

  20. Nanoscale zero-valent metals: a review of synthesis, characterization, and applications to environmental remediation.

    Science.gov (United States)

    Li, Lingyun; Hu, Jiwei; Shi, Xuedan; Fan, Mingyi; Luo, Jin; Wei, Xionghui

    2016-09-01

    Engineered nanoscale zero-valent metals (NZVMs) representing the forefront of technologies have been considered as promising materials for environmental remediation and antimicrobial effect, due to their high reducibility and strong adsorption capability. This review is focused on the methodology for synthesis of bare NZVMs, supported NZVMs, modified NZVMs, and bimetallic systems with both traditional and green methods. Recent studies have demonstrated that self-assembly methods can play an important role for obtaining ordered, controllable, and tunable NZVMs. In addition to common characterization methods, the state-of-the-art methods have been developed to obtain the properties of NZVMs (e.g., granularity, size distribution, specific surface area, shape, crystal form, and chemical bond) with the resolution down to subnanometer scale. These methods include spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), electron energy-loss spectroscopy (EELS), and near edge X-ray absorption fine structure (NEXAFS). A growing body of experimental data has proven that nanoscale zero-valent iron (NZVI) is highly effective and versatile. This article discusses the applications of NZVMs to treatment of heavy metals, halogenated organic compounds, polycyclic aromatic hydrocarbons, nutrients, radioelements, and microorganisms, using both ex situ and in situ methods. Furthermore, this paper briefly describes the ecotoxicological effects for NZVMs and the research prospects related to their synthesis, modification, characterization, and applications.

  1. Gold Nanoparticles for Plasmonic Biosensing: The Role of Metal Crystallinity and Nanoscale Roughness

    CERN Document Server

    Tinguely, Jean-Claude; Leiner, Claude; Grand, Johan; Hohenau, Andreas; Felidj, Nordin; Aubard, Jean; Krenn, Joachim R

    2011-01-01

    Noble metal nanoparticles show specific optical properties due to the excitation of localized surface plasmons that make them attractive candidates for highly sensitive bionanosensors. The underlying physical principle is either an analyte-induced modification of the dielectric properties of the medium surrounding the nanoparticle or an increase of the excitation and emission rates of an optically active analyte by the resonantly enhanced plasmon field. Either way, besides the nanoparticle geometry the dielectric properties of the metal and nanoscale surface roughness play an important role for the sensing performance. As the underlying principles are however not yet well understood, we aim here at an improved understanding by analyzing the optical characteristics of lithographically fabricated nanoparticles with different crystallinity and roughness parameters. We vary these parameters by thermal annealing and apply a thin gold film as a model system to retrieve modifications in the dielectric function. We i...

  2. Nanoscale Potentiometry and Spectroscopy of Organic Electronic and Photonic Materials and Devices using Conductive Atomic Force Microscopy

    Science.gov (United States)

    Hersam, M. C.; Fabbroni, E. F.; Such, M. W.; Shull, K. R.; Veinot, J. G. C.; Marks, T. J.

    2002-03-01

    As organic devices approach the nanometer scale, spatial variations in the electronic and photonic properties of organic materials become increasingly significant. To this end, we have developed conductive atomic force microscopy techniques for measuring temporally and spatially dependent electronic and photonic signals. To test this general nanocharacterization technique, two model organic systems have been studied: (1) a polyethylene-co-maleic anhydride matrix filled with aggregates of carbon black particles and (2) organic light emitting diode (OLED) structures. In the first case, surface potentiometry measurements illustrate individual nanoscale agglomerates of highly conductive carbon black particles within the insulating matirx. In the OLED experiments, electron transport and photon emission are concurrently mapped with 10 nm spatial resolution. Ultimately, we correlate these nanoscale measurements with macroscopic device behavior.

  3. Inelastic transport theory from first principles: Methodology and application to nanoscale devices

    DEFF Research Database (Denmark)

    Frederiksen, Thomas; Paulsson, Magnus; Brandbyge, Mads

    2007-01-01

    We describe a first-principles method for calculating electronic structure, vibrational modes and frequencies, electron-phonon couplings, and inelastic electron transport properties of an atomic-scale device bridging two metallic contacts under nonequilibrium conditions. The method extends...... approximation. While these calculations often are computationally demanding, we show how they can be approximated by a simple and efficient lowest order expansion. Our method also addresses effects of energy dissipation and local heating of the junction via detailed calculations of the power flow. We...

  4. Layered reduced graphene oxide with nanoscale interlayer gaps as a stable host for lithium metal anodes

    Science.gov (United States)

    Lin, Dingchang; Liu, Yayuan; Liang, Zheng; Lee, Hyun-Wook; Sun, Jie; Wang, Haotian; Yan, Kai; Xie, Jin; Cui, Yi

    2016-07-01

    Metallic lithium is a promising anode candidate for future high-energy-density lithium batteries. It is a light-weight material, and has the highest theoretical capacity (3,860 mAh g-1) and the lowest electrochemical potential of all candidates. There are, however, at least three major hurdles before lithium metal anodes can become a viable technology: uneven and dendritic lithium deposition, unstable solid electrolyte interphase and almost infinite relative dimension change during cycling. Previous research has tackled the first two issues, but the last is still mostly unsolved. Here we report a composite lithium metal anode that exhibits low dimension variation (˜20%) during cycling and good mechanical flexibility. The anode is composed of 7 wt% ‘lithiophilic’ layered reduced graphene oxide with nanoscale gaps that can host metallic lithium. The anode retains up to ˜3,390 mAh g-1 of capacity, exhibits low overpotential (˜80 mV at 3 mA cm-2) and a flat voltage profile in a carbonate electrolyte. A full-cell battery with a LiCoO2 cathode shows good rate capability and flat voltage profiles.

  5. Nanoscale surface modifications of medically relevant metals: state-of-the art and perspectives

    Science.gov (United States)

    Variola, Fabio; Brunski, John B.; Orsini, Giovanna; Tambasco de Oliveira, Paulo; Wazen, Rima; Nanci, Antonio

    2011-02-01

    Evidence that nanoscale surface properties stimulate and guide various molecular and biological processes at the implant/tissue interface is fostering a new trend in designing implantable metals. Cutting-edge expertise and techniques drawn from widely separated fields, such as nanotechnology, materials engineering and biology, have been advantageously exploited to nanoengineer surfaces in ways that control and direct these processes in predictable manners. In this review, we present and discuss the state-of-the-art of nanotechnology-based approaches currently adopted to modify the surface of metals used for orthopedic and dental applications, and also briefly consider their use in the cardiovascular field. The effects of nanoengineered surfaces on various in vitro molecular and cellular events are firstly discussed. This review also provides an overview of in vivo and clinical studies with nanostructured metallic implants, and addresses the potential influence of nanotopography on biomechanical events at interfaces. Ultimately, the objective of this work is to give the readership a comprehensive picture of the current advances, future developments and challenges in the application of the infinitesimally small to biomedical surface science. We believe that an integrated understanding of the in vitro and particularly of the in vivo behavior is mandatory for the proper exploitation of nanostructured implantable metals and, indeed, of all biomaterials.

  6. The investigation of nanoscale effects on schottky interfaces and the scattering rates of high resistivity metals

    Science.gov (United States)

    Durcan, Christopher

    Understanding the transport of electrons through materials and across interfaces is fundamental to modern day electronics. As electrons travel, interactions with defects within the crystal lattice induce scattering which gives rise to resistivity. At the interface between two materials, electrostatic barriers exist which can impede the flow of electrons. The work of this thesis is to further the understanding of electron transport by measuring the transport across metal-semiconductor interfaces at the nanoscale and measure scattering phenomena in metals. The measurement technique ballistic electron emission microscopy (BEEM) was used due to its ability to probe the scattering processes within a metal film and across metal semiconductor interfaces with nanoscale resolution. It was discovered that the hot electron transmission of the W/Si(001) Schottky barrier decreases over a period of 21 days with the initial Schottky barrier height of 0.71eV decreasing to 0.62eV. The spatial map changes dramatically from 98% of the spectra able to be fit to only 27%. This is supported by transmission electron microscopy (TEM) showing the formation of a tungsten silicide which increases in thickness. It was discovered that the deposition of tungsten on silicon using electron beam evaporation and RF magnetron sputtering resulted in dramatic differences in the Schottky barrier height and transport of hot electrons. A difference of ˜70meV was measured in the Schottky barrier height's for both p-type and n-type silicon. Spatial maps show a uniform barrier height for the sputter film and varying barrier height for the e-beam film. Histograms show a symmetric gaussian profile for the sputtered film and an asymmetric profile for the evaporated film, arising from an increase in elastic scattering. The hot electron attenuation length of tungsten and chromium thin films were measured on Si(001) and Si(111) substrates. An attenuation length of 2.26nm was measured at 1.0V bias for tungsten

  7. Pseudo-One-Dimensional Magnonic Crystals for High-Frequency Nanoscale Devices

    Science.gov (United States)

    Banerjee, Chandrima; Choudhury, Samiran; Sinha, Jaivardhan; Barman, Anjan

    2017-07-01

    The synthetic magnonic crystals (i.e., periodic composites consisting of different magnetic materials) form one fascinating class of emerging research field, which aims to command the process and flow of information by means of spin waves, such as in magnonic waveguides. One of the intriguing features of magnonic crystals is the presence and tunability of band gaps in the spin-wave spectrum, where the high attenuation of the frequency bands can be utilized for frequency-dependent control on the spin waves. However, to find a feasible way of band tuning in terms of a realistic integrated device is still a challenge. Here, we introduce an array of asymmetric saw-tooth-shaped width-modulated nanoscale ferromagnetic waveguides forming a pseudo-one-dimensional magnonic crystal. The frequency dispersion of collective modes measured by the Brillouin light-scattering technique is compared with the band diagram obtained by numerically solving the eigenvalue problem derived from the linearized Landau-Lifshitz magnetic torque equation. We find that the magnonic band-gap width, position, and the slope of dispersion curves are controllable by changing the angle between the spin-wave propagation channel and the magnetic field. The calculated profiles of the dynamic magnetization reveal that the corrugation at the lateral boundary of the waveguide effectively engineers the edge modes, which forms the basis of the interactive control in magnonic circuits. The results represent a prospective direction towards managing the internal field distribution as well as the dispersion properties, which find potential applications in dynamic spin-wave filters and magnonic waveguides in the gigahertz frequency range.

  8. Multiscale examination and modeling of electron transport in nanoscale materials and devices

    Science.gov (United States)

    Banyai, Douglas R.

    For half a century the integrated circuits (ICs) that make up the heart of electronic devices have been steadily improving by shrinking at an exponential rate. However, as the current crop of ICs get smaller and the insulating layers involved become thinner, electrons leak through due to quantum mechanical tunneling. This is one of several issues which will bring an end to this incredible streak of exponential improvement of this type of transistor device, after which future improvements will have to come from employing fundamentally different transistor architecture rather than fine tuning and miniaturizing the metal-oxide-semiconductor field effect transistors (MOSFETs) in use today. Several new transistor designs, some designed and built here at Michigan Tech, involve electrons tunneling their way through arrays of nanoparticles. We use a multi-scale approach to model these devices and study their behavior. For investigating the tunneling characteristics of the individual junctions, we use a first-principles approach to model conduction between sub-nanometer gold particles. To estimate the change in energy due to the movement of individual electrons, we use the finite element method to calculate electrostatic capacitances. The kinetic Monte Carlo method allows us to use our knowledge of these details to simulate the dynamics of an entire device---sometimes consisting of hundreds of individual particles---and watch as a device 'turns on' and starts conducting an electric current. Scanning tunneling microscopy (STM) and the closely related scanning tunneling spectroscopy (STS) are a family of powerful experimental techniques that allow for the probing and imaging of surfaces and molecules at atomic resolution. However, interpretation of the results often requires comparison with theoretical and computational models. We have developed a new method for calculating STM topographs and STS spectra. This method combines an established method for approximating the

  9. Controlling terahertz radiation with nanoscale metal barriers embedded in nano slot antennas.

    Science.gov (United States)

    Park, Hyeong-Ryeol; Bahk, Young-Mi; Ahn, Kwang Jun; Park, Q-Han; Kim, Dai-Sik; Martín-Moreno, Luis; García-Vidal, Francisco J; Bravo-Abad, Jorge

    2011-10-25

    Nanoscale metallic barriers embedded in terahertz (THz) slot antennas are shown to provide unprecedented control of the transition state arising at the crossover between the full- and half-wavelength resonant modes of such antennas. We demonstrate strong near-field coupling between two paired THz slot antennas separated by a 5 nm wide nanobarrier, almost fully inducing the shift to the resonance of the double-length slot antenna. This increases by a factor of 50 the length-scale needed to observe similar coupling strengths in conventional air-gap antennas (around 0.1 nm), making the transition state readily accessible to experiment. Our measurements are in good agreement with a quantitative theoretical modeling, which also provides a simple physical picture of our observations.

  10. Second harmonic generation in nanoscale films of transition metal chalcogenides: Taking into account multibeam interference

    Science.gov (United States)

    Lavrov, S. D.; Kudryavtsev, A. V.; Shestakova, A. P.; Kulyuk, L.; Mishina, E. D.

    2016-05-01

    Second harmonic generation is studied in structures containing nanoscale layers of transition metal chalcogenides that are two-dimensional semiconductors and deposited on a SiO2/Si substrate. The second harmonic generation intensity is calculated with allowance for multibeam interference in layers of dichalcogenide and silicon oxide. The coefficient of reflection from the SiO2-layer-based Fabry-Perot cavity is subsequently calculated for pump wave fields initiating nonlinear polarization at every point of dichalcogenide, which is followed by integration of all second harmonic waves generated by this polarization. Calculated second harmonic intensities are presented as functions of dichalcogenide and silicon oxide layer thicknesses. The dependence of the second harmonic intensity on the MoS2 layer thickness is studied experimentally in the layer of 2-140 nm. A good coincidence of the experimental data and numerical simulation results has been obtained.

  11. Probing elasticity at the nanoscale: Terahertz acoustic vibration of small metal nanoparticles.

    Science.gov (United States)

    Juvé, Vincent; Crut, Aurélien; Maioli, Paolo; Pellarin, Michel; Broyer, Michel; Del Fatti, Natalia; Vallée, Fabrice

    2010-05-12

    The acoustic response of surface-controlled metal (Pt) nanoparticles is investigated in the small size range, between 1.3 and 3 nm (i.e., 75-950 atoms), using time-resolved spectroscopy. Acoustic vibration of the nanoparticles is demonstrated, with frequencies ranging from 1.1 to 2.6 THz, opening the way to the development of THz acoustic resonators. The frequencies, measured with a noncontact optical method, are in excellent agreement with the prediction of a macroscopic approach based on the continuous elastic model, together with the bulk material elastic constants. This demonstrates the validity of this model at the nanoscale and the weak impact of size reduction on the elastic properties of a material, even for nanoparticles formed by less than 100 atoms.

  12. Nanoscale “Quantum” Islands on Metal Substrates: Microscopy Studies and Electronic Structure Analyses

    Directory of Open Access Journals (Sweden)

    Da-Jiang Liu

    2010-07-01

    Full Text Available Confinement of electrons can occur in metal islands or in continuous films grown heteroepitaxially upon a substrate of a different metal or on a metallic alloy. Associated quantum size effects (QSE can produce a significant height-dependence of the surface free energy for nanoscale thicknesses of up to 10–20 layers. This may suffice to induce height selection during film growth. Scanning STM analysis has revealed remarkable flat-topped or mesa-like island and film morphologies in various systems. We discuss in detail observations of QSE and associated film growth behavior for Pb/Cu(111, Ag/Fe(100, and Cu/fcc-Fe/Cu(100 [A/B or A/B/A], and for Ag/NiAl(110 with brief comments offered for Fe/Cu3Au(001 [A/BC binary alloys]. We also describe these issues for Ag/5-fold i-Al-Pd-Mn and Bi/5-fold i-Al-Cu-Fe [A/BCD ternary icosohedral quasicrystals]. Electronic structure theory analysis, either at the level of simple free electron gas models or more sophisticated Density Functional Theory calculations, can provide insight into the QSE-mediated thermodynamic driving force underlying height selection.

  13. Nanoscale capillary freezing of ionic liquids confined between metallic interfaces and the role of electronic screening

    Science.gov (United States)

    Comtet, Jean; Niguès, Antoine; Kaiser, Vojtech; Coasne, Benoit; Bocquet, Lydéric; Siria, Alessandro

    2017-06-01

    Room-temperature ionic liquids (RTILs) are new materials with fundamental importance for energy storage and active lubrication. They are unusual liquids, which challenge the classical frameworks of electrolytes, whose behaviour at electrified interfaces remains elusive, with exotic responses relevant to their electrochemical activity. Using tuning-fork-based atomic force microscope nanorheological measurements, we explore here the properties of confined RTILs, unveiling a dramatic change of the RTIL towards a solid-like phase below a threshold thickness, pointing to capillary freezing in confinement. This threshold is related to the metallic nature of the confining materials, with more metallic surfaces facilitating freezing. This behaviour is interpreted in terms of the shift of the freezing transition, taking into account the influence of the electronic screening on RTIL wetting of the confining surfaces. Our findings provide fresh views on the properties of confined RTIL with implications for their properties inside nanoporous metallic structures, and suggests applications to tune nanoscale lubrication with phase-changing RTILs, by varying the nature and patterning of the substrate, and application of active polarization.

  14. Smart textile device using ion polymer metal compound.

    Science.gov (United States)

    Nakamura, Taro; Ihara, Tadashi

    2013-01-01

    We have developed a smart textile device that detects angular displacement of attached surface using ion polymer metal compound. The device was composed of ion polymer metal compound (IPMC) which was fabricated from Nafion resin by heat-press and chemical gold plating. The generated voltage from IPMC was measured as a function of bending angle. Fabricated IPMC device was weaved into a cotton cloth and multidirectional movements were detected.

  15. Characterization of structural and electronic properties of nanoscale semiconductor device structures using cross-sectional scanning probe microscopy

    Science.gov (United States)

    Rosenthal, Paul Arthur

    Scanning probe microscopy (SPM) offers numerous advantages over metrology tools traditionally used for semiconductor materials and device characterization including high lateral spatial resolution, and relative ease of use. Cross-sectional SPM allows material and device measurements including layer thickness metrology and p-n junction delineation on actual nanoscale device structures. Site-specific SPM allows measurements to be performed on modern devices with real, non-arbitrary geometries including deep-submicron Si device structures. In Chapter II we present theoretical analysis and experimental results of capacitive force microscopy studies of AlxGa1-xAs/GaAs heterojunction bipolar transistor structures. The contrast obtained yields clear delineation of individual device layers based on doping, and enables a precise determination of the difference in basewidth between the two HBT samples examined. We experimentally determine a charged surface state density on the GaAs {110} surface that is consistent with published values. In Chapter III we present cross-sectional scanning capacitance microscopy (SCM) of nanoscale group IV Si device structures. Sample preparation techniques are discussed in context with recent experimental results from the literature. We then presented a theoretical calculation of the flat-band and threshold voltage of Si-MOSFETs as a function of doping including error analysis due to oxide thickness variations. Application to nanoscale FIB implanted Si is presented. The SCM contrast evolves as a function of applied bias as expected based on theoretical modeling of the tip-sample system as an MOS-capacitor. In Chapter IV we apply cross-sectional SCM to directly measure the electronic properties of a 120 nm gate length p-MOSFET including super-halo implants. Bias-dependent SCM images allow us to delineate the individual device regions and image the n+ super-halo implants. We have demonstrated the specific SCM bias conditions necessary for

  16. Metallization of bacterial cellulose for electrical and electronic device manufacture

    Science.gov (United States)

    Evans, Barbara R.; O'Neill, Hugh M.; Jansen, Valerie Malyvanh; Woodward, Jonathan

    2011-06-07

    A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

  17. Nanoscale photonics using coupled hybrid plasmonic architectures

    Science.gov (United States)

    Lin, Charles; Su, Yiwen; Helmy, Amr S.

    2016-04-01

    Plasmonic waveguides, which support surface plasmon polaritons (SPP) propagating along metal-dielectric interfaces, offer strong field confinement and are ideal for the design of integrated nano-scale photonic devices. However, due to free-carrier absorption in the metal, the enhanced mode confinement inevitably entails an increase in the waveguide loss. This lowers the device figure-of-merit achievable with passive plasmonic components and in turn hinders the performance of active plasmonic components such as optical modulators.

  18. Heavy metal removal using nanoscale zero-valent iron (nZVI): Theory and application

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shaolin, E-mail: lishaolin@tongji.edu.cn; Wang, Wei; Liang, Feipeng; Zhang, Wei-xian, E-mail: zhangwx@tongji.edu.cn

    2017-01-15

    Highlights: • nZVI is able to perform fast and simultaneous removal of different heavy metal ions. • Fast separation and seeding effect of nZVI facilities its application in wastewater. • A novel process of E{sub h}-controlled reactor, nZVI separator and reuse is proposed. • E{sub h}-controlled system and nZVI recirculation increase material efficiency of nZVI. • The process produces stable effluent and is effective in wastewater treatment. - Abstract: Treatment of wastewater containing heavy metals requires considerations on simultaneous removal of different ions, system reliability and quick separation of reaction products. In this work, we demonstrate that nanoscale zero-valent iron (nZVI) is an ideal reagent for removing heavy metals from wastewater. Batch experiments show that nZVI is able to perform simultaneous removal of different heavy metals and arsenic; reactive nZVI in uniform dispersion brings rapid changes in solution E{sub h}, enabling a facile way for reaction regulation. Microscope characterizations and settling experiments suggest that nZVI serves as solid seeds that facilitate products separation. A treatment process consisting of E{sub h}-controlled nZVI reaction, gravitational separation and nZVI recirculation is then demonstrated. Long-term (>12 months) operation shows that the process achieves >99.5% removal of As, Cu and a number of other toxic elements. The E{sub h}-controlled reaction system sustains a highly-reducing condition in reactor and reduces nZVI dosage. The process produces effluent of stable quality that meets local discharge guidelines. The gravitational separator shows high efficacy of nZVI recovery and the recirculation improves nZVI material efficiency, resulting in extraordinarily high removal capacities ((245 mg As + 226 mg-Cu)/g-nZVI). The work provides proof that nanomaterials can offer truly green and cost-effective solutions for wastewater treatment.

  19. Nanoscale mechano-electronic behavior of a metalloprotein as a variable of metal content.

    Science.gov (United States)

    Rakshit, Tatini; Banerjee, Siddhartha; Mishra, Sourav; Mukhopadhyay, Rupa

    2013-10-01

    In this work, we have explored an approach to finding a correlation between the mechanical response of a metalloprotein against a range of applied force (by force curve analysis) and its electrical response under pressure stimulation (by current sensing atomic force spectroscopy) at the nanoscale. Iron-storage protein ferritin has been chosen as an experimental model system because it naturally contains a semiconducting iron core. This core consists of a large number of iron atoms and is therefore expected to exert a clear influence on the overall mechanical response of the protein structure. Four different ferritins (apoferritin, Fe(III)-ferritins containing ~750 and ~1400 iron atoms, and holoferritin containing ~2600 iron atoms) were chosen in order to identify any relation between the mechano-electronic behavior of the ferritins and their metal content. We report the measurement of Young's modulus values of the ferritin proteins as applicable in a nanoscale environment, for the first time, and show that these values are directly linked to the iron content of the individual ferritin type. The greater the iron content, the greater the Young's modulus and in general the slower the rate of deformation against the application of force. When compressed, all the four ferritins exhibited increased electronic conductivity. A correlation between the iron content of the ferritins and the current values observed at certain bias voltages could be made at higher bias values (beyond 0.7 V), but no such discrimination among the four compressed ferritins could be made at the lower voltages. We propose that only at higher voltages can the iron atoms that reside deeper inside the core of the ferritins be accessed. The iron atoms that could be situated at the inner wall of the protein shell appear to make a general contribution to the electronic conductivity of the four ferritin systems.

  20. Metal-organic frameworks as templates for nanoscale NaAlH4.

    Science.gov (United States)

    Bhakta, Raghunandan K; Herberg, Julie L; Jacobs, Benjamin; Highley, Aaron; Behrens, Richard; Ockwig, Nathan W; Greathouse, Jeffery A; Allendorf, Mark D

    2009-09-23

    Metal-organic frameworks (MOFs) offer an attractive alternative to traditional hard and soft templates for nanocluster synthesis because their ordered crystalline lattice provides a highly controlled and inherently understandable environment. We demonstrate that MOFs are stable hosts for metal hydrides proposed for hydrogen storage and their reactive precursors, providing platform to test recent theoretical predictions that some of these materials can be destabilized with respect to hydrogen desorption by reducing their critical dimension to the nanoscale. With the MOF HKUST-1 as template, we show that NaAlH(4) nanoclusters as small as eight formula units can be synthesized. The confinement of these clusters within the MOF pores dramatically accelerates the desorption kinetics, causing decomposition to occur at approximately 100 degrees C lower than bulk NaAlH(4). However, using simultaneous thermogravimetric modulated beam mass spectrometry, we also show that the thermal decomposition mechanism of NaAlH(4) is complex and may involve processes such as nucleation and growth in addition to the normally assumed two-step chemical decomposition reactions.

  1. Nanoscale Metal-Organic Particles with Rapid Clearance for Magnetic Resonance Imaging-Guided Photothermal Therapy.

    Science.gov (United States)

    Yang, Yu; Liu, Jingjing; Liang, Chao; Feng, Liangzhu; Fu, Tingting; Dong, Ziliang; Chao, Yu; Li, Yonggang; Lu, Guang; Chen, Meiwan; Liu, Zhuang

    2016-02-23

    Nanoscale metal-organic particles (NMOPs) are constructed from metal ions and organic bridging ligands via the self-assembly process. Herein, we fabricate NMOPs composed of Mn(2+) and a near-infrared (NIR) dye, IR825, obtaining Mn-IR825 NMOPs, which are then coated with a shell of polydopamine (PDA) and further functionalized with polyethylene glycol (PEG). While Mn(2+) in such Mn-IR825@PDA-PEG NMOPs offers strong contrast in T1-weighted magnetic resonance (MR) imaging, IR825 with strong NIR optical absorbance shows efficient photothermal conversion with great photostability in the NMOP structure. Upon intravenous injection, Mn-IR825@PDA-PEG shows efficient tumor homing together with rapid renal excretion behaviors, as revealed by MR imaging and confirmed by biodistribution measurement. Notably, when irradiated with an 808 nm laser, tumors on mice with Mn-IR825@PDA-PEG injection are completely eliminated without recurrence within 60 days, demonstrating the high efficacy of photothermal therapy with this agent. This study demonstrates the use of NMOPs as a potential photothermal agent, which features excellent tumor-targeted imaging and therapeutic functions, together with rapid renal excretion behavior, the latter of which would be particularly important for future clinical translation of nanomedicine.

  2. Memory and Spin Injection Devices Involving Half Metals

    Directory of Open Access Journals (Sweden)

    M. Shaughnessy

    2011-01-01

    Full Text Available We suggest memory and spin injection devices fabricated with half-metallic materials and based on the anomalous Hall effect. Schematic diagrams of the memory chips, in thin film and bulk crystal form, are presented. Spin injection devices made in thin film form are also suggested. These devices do not need any external magnetic field but make use of their own magnetization. Only a gate voltage is needed. The carriers are 100% spin polarized. Memory devices may potentially be smaller, faster, and less volatile than existing ones, and the injection devices may be much smaller and more efficient than existing spin injection devices.

  3. Nanoscale device architectures derived from biological assemblies: The case of tobacco mosaic virus and (apo)ferritin

    Science.gov (United States)

    Calò, Annalisa; Eiben, Sabine; Okuda, Mitsuhiro; Bittner, Alexander M.

    2016-03-01

    Virus particles and proteins are excellent examples of naturally occurring structures with well-defined nanoscale architectures, for example, cages and tubes. These structures can be employed in a bottom-up assembly strategy to fabricate repetitive patterns of hybrid organic-inorganic materials. In this paper, we review methods of assembly that make use of protein and virus scaffolds to fabricate patterned nanostructures with very high spatial control. We chose (apo)ferritin and tobacco mosaic virus (TMV) as model examples that have already been applied successfully in nanobiotechnology. Their interior space and their exterior surfaces can be mineralized with inorganic layers or nanoparticles. Furthermore, their native assembly abilities can be exploited to generate periodic architectures for integration in electrical and magnetic devices. We introduce the state of the art and describe recent advances in biomineralization techniques, patterning and device production with (apo)ferritin and TMV.

  4. Metal sulfide electrodes and energy storage devices thereof

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Woodford, William Henry; Li, Zheng; Carter, W. Craig

    2017-02-28

    The present invention generally relates to energy storage devices, and to metal sulfide energy storage devices in particular. Some aspects of the invention relate to energy storage devices comprising at least one flowable electrode, wherein the flowable electrode comprises an electroactive metal sulfide material suspended and/or dissolved in a carrier fluid. In some embodiments, the flowable electrode further comprises a plurality of electronically conductive particles suspended and/or dissolved in the carrier fluid, wherein the electronically conductive particles form a percolating conductive network. An energy storage device comprising a flowable electrode comprising a metal sulfide electroactive material and a percolating conductive network may advantageously exhibit, upon reversible cycling, higher energy densities and specific capacities than conventional energy storage devices.

  5. Nanoscale size dependence on pulsed laser sintering of hydroxyapatite/titanium particles on metal implants

    Science.gov (United States)

    Zhang, Martin Yi; Cheng, Gary J.

    2010-12-01

    Nanoscale size effects on pulsed laser coating of hydroxyapatite/titanium nanoparticles (nanoTi) on metal substrate is discussed in this article. Laser coating method has recently been developed to coat bioceramics material on Ti-6Al-4V substrate. Laser-coated bioceramics implants have several advantages due to the use of nanosized materials: strong interfacial bonding strength, good biocompatibility and potentially longer lifetime cycle. These advantages benefit from intrinsic properties of nanoparticles. Size effects on melting point, heat capacity, thermal, and electrical conductivities have been discussed. Multiphysics model is built to reveal the mechanism of laser coating process. Two submodules are included in the model: electromagnetic module to represent the laser-nanoparticle interactions and heat transfer module to simulate the heat conduction. Both simulation and experimental results showed that nanoTi, functioning as nanoheaters, effectively enhances the laser coating sinterability. For large nanoTi (>100 nm), sinterability enhancement mainly attributes to the stronger laser-particle interactions due to higher plasmon resonance; for small nanoparticles (<100 nm), not only stronger laser-nanoparticle interactions, reduction on melting point also contributes to sinterability enhancement.

  6. Metal-insulator transition and nanoscale phase separation in a hole-doped surface reconstruction

    Science.gov (United States)

    Mulugeta, Daniel; Snijders, Paul; Weitering, Hanno

    2014-03-01

    Doping, the deliberate introduction of impurities to alter electronic or magnetic properties, has been a tremendously successful method to study and understand systems with multiple competing interactions, as reflected in both the widespread use of doped semiconductors and in the large number of emergent electronic phases in doping-dependent phase diagrams of e.g. complex oxides. In low dimensional systems, however, the perturbation to the crystal lattice by the dopant atoms can overwhelm a delicate balance of interactions in e.g. a ground state with coexisting phases. Here we introduce a modulation doping technique used to dope holes in a surface reconstruction of Sn on Si(111). Using variable and low temperature scanning tunneling microscopy and spectroscopy, we observe a doping-induced metal-insulator phase transition that is of a displacive nature, contrasting with the order-disorder nature of other surface phase transitions. Moreover, the transition leads to an intrinsic nanoscale phase coexistence at 5 K never before observed on semiconductor surfaces. Clearly, modulation doping allows us to study the delicate balance of interactions in the phase diagram of low-dimensional electronic surface systems that is otherwise experimentally inaccessible. Funded by NSF DMR.

  7. Harnessing microbial subsurface metal reduction activities to synthesise nanoscale cobalt ferrite with enhanced magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Coker, Victoria S.; Telling, Neil D.; van der Laan, Gerrit; Pattrick, Richard A.D.; Pearce, Carolyn I.; Arenholz, Elke; Tuna, Floriana; Winpenny, Richard E.P.; Lloyd, Jonathan R.

    2009-03-24

    Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of {approx} 10{sup 6} erg cm{sup -3} can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies. Production of ferromagnetic nanoparticles for pioneering cancer therapy, drug delivery, chemical sensors, catalytic activity, photoconductive materials, as well as more traditional uses in data storage embodies a large area of inorganic synthesis research. In particular, the addition of transition metals other than

  8. Nanoscale temperature sensing using the Seebeck effect

    NARCIS (Netherlands)

    Bakker, F. L.; Flipse, J.; van Wees, B. J.

    2012-01-01

    We experimentally study the effect of Joule heating on the electron temperature in metallic nanoscale devices and compare the results with a diffusive 3D finite element model. The temperature is probed using four thermocouples located at different distances from the heater. A good quantitative agree

  9. Nanoscale temperature sensing using the Seebeck effect

    NARCIS (Netherlands)

    Bakker, F. L.; Flipse, J.; van Wees, B. J.

    2012-01-01

    We experimentally study the effect of Joule heating on the electron temperature in metallic nanoscale devices and compare the results with a diffusive 3D finite element model. The temperature is probed using four thermocouples located at different distances from the heater. A good quantitative

  10. Nanoscale phase change memory materials.

    Science.gov (United States)

    Caldwell, Marissa A; Jeyasingh, Rakesh Gnana David; Wong, H-S Philip; Milliron, Delia J

    2012-08-01

    Phase change memory materials store information through their reversible transitions between crystalline and amorphous states. For typical metal chalcogenide compounds, their phase transition properties directly impact critical memory characteristics and the manipulation of these is a major focus in the field. Here, we discuss recent work that explores the tuning of such properties by scaling the materials to nanoscale dimensions, including fabrication and synthetic strategies used to produce nanoscale phase change memory materials. The trends that emerge are relevant to understanding how such memory technologies will function as they scale to ever smaller dimensions and also suggest new approaches to designing materials for phase change applications. Finally, the challenges and opportunities raised by integrating nanoscale phase change materials into switching devices are discussed.

  11. NASA GSFC Strategic Nanotechnology Interests: Symposium on High-Rate Nanoscale Printing for Devices and Structures

    Science.gov (United States)

    Ericsson, Aprille J.

    2014-01-01

    The seminars invitees include representatives from industry, nonprofit research facility and universities. The presentation provides an overview of the NASAGSFC locations, technical capabilities and applied nanotechnology interests. Initially presented are advances by the broader technological communities on current miniaturized multiscale advanced manufacturing and 3D printing products on the micro and macro scale. Briefly assessed is the potential of moving toward the nanoscale for possible space flight applications and challenges. Lastly, highlighted are GSFCs current successes in nano-technology developments and targeted future applications.

  12. Nanoscale thermometry using point contact thermocouples.

    Science.gov (United States)

    Sadat, Seid; Tan, Aaron; Chua, Yi Jie; Reddy, Pramod

    2010-07-14

    Probing temperature fields with nanometer resolution is critical to understanding nanoscale thermal transport as well as dissipation in nanoscale devices. Here, we demonstrate an atomic force microscope (AFM)-based technique capable of mapping temperature fields in metallic films with approximately 10 mK temperature resolution and thermocouples on a grid. The local temperature at each point contact is obtained by measuring the thermoelectric voltage of the platinum-gold point contact and relating it to the local temperature. These results demonstrate a direct measurement of the temperature field of a metallic surface without using specially fabricated scanning temperature-probes.

  13. Nanoscale Joule heating, Peltier cooling and current crowding at graphene-metal contacts

    Science.gov (United States)

    Grosse, Kyle L.; Bae, Myung-Ho; Lian, Feifei; Pop, Eric; King, William P.

    2011-05-01

    The performance and scaling of graphene-based electronics is limited by the quality of contacts between the graphene and metal electrodes. However, the nature of graphene-metal contacts remains incompletely understood. Here, we use atomic force microscopy to measure the temperature distributions at the contacts of working graphene transistors with a spatial resolution of ~10 nm (refs 5, , , 8), allowing us to identify the presence of Joule heating, current crowding and thermoelectric heating and cooling. Comparison with simulation enables extraction of the contact resistivity (150-200 Ω µm2) and transfer length (0.2-0.5 µm) in our devices; these generally limit performance and must be minimized. Our data indicate that thermoelectric effects account for up to one-third of the contact temperature changes, and that current crowding accounts for most of the remainder. Modelling predicts that the role of current crowding will diminish and the role of thermoelectric effects will increase as contacts improve.

  14. Motion of Fullerenes around Topological Defects on Metals: Implications for the Progress of Molecular Scale Devices.

    Science.gov (United States)

    Nirmalraj, Peter; Daly, Ronan; Martin, Nazario; Thompson, Damien

    2017-03-08

    Research on motion of molecules in the presence of thermal noise is central for progress in two-terminal molecular scale electronic devices. However, it is still unclear what influence imperfections in bottom metal electrode surface can have on molecular motion. Here, we report a two-layer crowding study, detailing the early stages of surface motion of fullerene molecules on Au(111) with nanoscale pores in a n-tetradecane chemical environment. The motion of the fullerenes is directed by crowding of the underlying n-tetradecane molecules around the pore fringes at the liquid-solid interface. We observe in real-space the growth of molecular populations around different pore geometries. Supported by atomic-scale modeling, our findings extend the established picture of molecular crowding by revealing that trapped solvent molecules serve as prime nucleation sites at nanopore fringes.

  15. Electrical properties of nanoscale metallic thin films on dielectric elastomer at various strain rates

    Science.gov (United States)

    Faisal, Md. Shahnewaz Sabit; Ye, Zhihang; Chen, Zheng; Asmatulu, Ramazan

    2015-04-01

    Dielectric elastomers (DEs) have significant applications in artificial muscle and other biomedical equipment and device fabrications. Metallic thin films by thin film transfer and sputter coating techniques can provide conductive surfaces on the DE samples, and can be used as electrodes for the actuators and other biomedical sensing devices. In the present study, 3M VHB 4910 tape was used as a DE for the coating and electrical characterization tests. A 150 nm thickness of gold was coated on the DE surfaces by sputter coating under vacuum with different pre-strains, ranging from 0 to 100%. Some of the thin films were transferred to the surface of the DEs. Sputter coating, and direct transferring gold leaf coating methods were studied and the results were analyzed in detail in terms of the strain rates and electrical resistivity changes. Initial studies indicated that the metallic surfaces remain conductive even though the DE films were considerably elongated. The coated DEs can be used as artificial muscle by applying electrical stimulation through the conductive surfaces. This study may provide great benefits to the readers, researchers, as well as companies involved in manufacturing of artificial muscles and actuators using smart materials.

  16. Nanoscale metal-organic frameworks for biomedical imaging and drug delivery.

    Science.gov (United States)

    Della Rocca, Joseph; Liu, Demin; Lin, Wenbin

    2011-10-18

    Metal-organic frameworks (MOFs), a class of hybrid materials formed by the self-assembly of polydentate bridging ligands and metal-connecting points, have been studied for a variety of applications. Recently, these materials have been scaled down to nanometer sizes, and this Account details the development of nanoscale metal-organic frameworks (NMOFs) for biomedical applications. NMOFs possess several potential advantages over conventional nanomedicines such as their structural and chemical diversity, their high loading capacity, and their intrinsic biodegradability. Under relatively mild conditions, NMOFs can be obtained as either crystalline or amorphous materials. The particle composition, size, and morphology can be easily tuned to optimize the final particle properties. Researchers have employed two general strategies to deliver active agents using NMOFs: by incorporating active agents into the frameworks or by loading active agents into the pores and channels of the NMOFs. The modification of NMOF surfaces with either silica coatings or organic polymers improves NMOF stability, fine-tunes their properties, and imparts additional functionality. Preliminary biomedical applications of NMOFs have focused on their use as delivery vehicles for imaging contrast agents and molecular therapeutics. Because NMOFs can carry large amounts of paramagnetic metal ions, they have been extensively explored as magnetic resonance imaging (MRI) contrast agents. Both Gd(3+)- and Mn(2+)-containing NMOFs have shown excellent efficacy as T(1)-weighted contrast agents with large per metal- and per particle-based MR relaxivities. Fe(3+)-containing NMOFs have demonstrated excellent T(2)-weighted contrast enhancement. Upon intravenous injection of iron carboxylate NMOFs in Wistar rats, researchers observed negative signal enhancement in the liver and spleen, which dissipated over time, indicating the degradation and clearance of the NMOF. Through the incorporation of luminescent or high

  17. All-polymer bistable resistive memory device based on nanoscale phase-separated PCBM-ferroelectric blends

    KAUST Repository

    Khan, Mohammad A.

    2012-11-21

    All polymer nonvolatile bistable memory devices are fabricated from blends of ferroelectric poly(vinylidenefluoride-trifluoroethylene (P(VDF-TrFE)) and n-type semiconducting [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The nanoscale phase separated films consist of PCBM domains that extend from bottom to top electrode, surrounded by a ferroelectric P(VDF-TrFE) matrix. Highly conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer electrodes are used to engineer band offsets at the interfaces. The devices display resistive switching behavior due to modulation of this injection barrier. With careful optimization of the solvent and processing conditions, it is possible to spin cast very smooth blend films (Rrms ≈ 7.94 nm) and with good reproducibility. The devices exhibit high Ion/I off ratios (≈3 × 103), low read voltages (≈5 V), excellent dielectric response at high frequencies (Ïμr ≈ 8.3 at 1 MHz), and excellent retention characteristics up to 10 000 s. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Nanoscale zero-valent iron for metal/metalloid removal from model hydraulic fracturing wastewater.

    Science.gov (United States)

    Sun, Yuqing; Lei, Cheng; Khan, Eakalak; Chen, Season S; Tsang, Daniel C W; Ok, Yong Sik; Lin, Daohui; Feng, Yujie; Li, Xiang-Dong

    2017-06-01

    Nanoscale zero-valent iron (nZVI) was tested for the removal of Cu(II), Zn(II), Cr(VI), and As(V) in model saline wastewaters from hydraulic fracturing. Increasing ionic strength (I) from 0.35 to 4.10 M (Day-1 to Day-90 wastewaters) increased Cu(II) removal (25.4-80.0%), inhibited Zn(II) removal (58.7-42.9%), slightly increased and then reduced Cr(VI) removal (65.7-44.1%), and almost unaffected As(V) removal (66.7-75.1%) by 8-h reaction with nZVI at 1-2 g L(-1). The removal kinetics conformed to pseudo-second-order model, and increasing I decreased the surface area-normalized rate coefficient (ksa) of Cu(II) and Cr(VI), probably because agglomeration of nZVI in saline wastewaters restricted diffusion of metal(loid)s to active surface sites. Increasing I induced severe Fe dissolution from 0.37 to 0.77% in DIW to 4.87-13.0% in Day-90 wastewater; and Fe dissolution showed a significant positive correlation with Cu(II) removal. With surface stabilization by alginate and polyvinyl alcohol, the performance of entrapped nZVI in Day-90 wastewater was improved for Zn(II) and Cr(VI), and Fe dissolution was restrained (3.20-7.36%). The X-ray spectroscopic analysis and chemical speciation modelling demonstrated that the difference in removal trends from Day-1 to Day-90 wastewaters was attributed to: (i) distinctive removal mechanisms of Cu(II) and Cr(VI) (adsorption, (co-)precipitation, and reduction), compared to Zn(II) (adsorption) and As(V) (bidentate inner-sphere complexation); and (ii) changes in solution speciation (e.g., from Zn(2+) to ZnCl3(-) and ZnCl4(2-); from CrO4(2-) to CaCrO4 complex). Bare nZVI was susceptible to variations in wastewater chemistry while entrapped nZVI was more stable and environmentally benign, which could be used to remove metals/metalloids before subsequent treatment for reuse/disposal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Engineering metal oxide structures for efficient photovoltaic devices

    Science.gov (United States)

    Concina, Isabella; Selopal, Gurpreet S.; Milan, Riccardo; Vomiero, Alberto; Sberveglieri, Giorgio

    2014-03-01

    Metal oxide-based photoanodes are critical components of dye sensitized solar cells (DSSCs), which are photoelectrochemical cells for the conversion of solar energy, promising to have several benefits as compared with their traditional counterparts. A careful engineering of the wide band gap metal oxide composing the photoanode, as well as their process design, is strategic for improving device performances and for planning a near future production scale up, especially devoted to reducing the environmental impact of the device fabrication. Herein, we present the application of ZnO hierarchical structures as efficient materials to be applied as photoanodes in DSSC, in the perspective of looking for alternative to TiO2 nanoparticles, currently the most exploited metal oxide in these devices.

  20. Nanoscale surface modifications to control capillary flow characteristics in PMMA microfluidic devices

    Directory of Open Access Journals (Sweden)

    Mukhopadhyay Subhadeep

    2011-01-01

    Full Text Available Abstract Polymethylmethacrylate (PMMA microfluidic devices have been fabricated using a hot embossing technique to incorporate micro-pillar features on the bottom wall of the device which when combined with either a plasma treatment or the coating of a diamond-like carbon (DLC film presents a range of surface modification profiles. Experimental results presented in detail the surface modifications in the form of distinct changes in the static water contact angle across a range from 44.3 to 81.2 when compared to pristine PMMA surfaces. Additionally, capillary flow of water (dyed to aid visualization through the microfluidic devices was recorded and analyzed to provide comparison data between filling time of a microfluidic chamber and surface modification characteristics, including the effects of surface energy and surface roughness on the microfluidic flow. We have experimentally demonstrated that fluid flow and thus filling time for the microfluidic device was significantly faster for the device with surface modifications that resulted in a lower static contact angle, and also that the incorporation of micro-pillars into a fluidic device increases the filling time when compared to comparative devices.

  1. Laser direct writing of micro- and nano-scale medical devices.

    Science.gov (United States)

    Gittard, Shaun D; Narayan, Roger J

    2010-05-01

    Laser-based direct writing of materials has undergone significant development in recent years. The ability to modify a variety of materials at small length scales and using short production times provides laser direct writing with unique capabilities for fabrication of medical devices. In many laser-based rapid prototyping methods, microscale and submicroscale structuring of materials is controlled by computer-generated models. Various laser-based direct write methods, including selective laser sintering/melting, laser machining, matrix-assisted pulsed-laser evaporation direct write, stereolithography and two-photon polymerization, are described. Their use in fabrication of microstructured and nanostructured medical devices is discussed. Laser direct writing may be used for processing a wide variety of advanced medical devices, including patient-specific prostheses, drug delivery devices, biosensors, stents and tissue-engineering scaffolds.

  2. Multi-physics simulation of metal printing at micro/nanoscale using meniscus-confined electrodeposition: Effect of environmental humidity

    Science.gov (United States)

    Morsali, Seyedreza; Daryadel, Soheil; Zhou, Zhong; Behroozfar, Ali; Qian, Dong; Minary-Jolandan, Majid

    2017-01-01

    Capability to print metals at micro/nanoscale in arbitrary 3D patterns at local points of interest will have applications in nano-electronics and sensors. Meniscus-confined electrodeposition (MCED) is a manufacturing process that enables depositing metals from an electrolyte containing nozzle (pipette) in arbitrary 3D patterns. In this process, a meniscus (liquid bridge or capillary) between the pipette tip and the substrate governs the localized electrodeposition process. Fabrication of metallic microstructures using this process is a multi-physics process in which electrodeposition, fluid dynamics, and mass and heat transfer physics are simultaneously involved. We utilized multi-physics finite element simulation, guided by experimental data, to understand the effect of water evaporation from the liquid meniscus at the tip of the nozzle for deposition of free-standing copper microwires in MCED process.

  3. Cellular nanoscale sensory wave computing

    CERN Document Server

    Baatar, Chagaan; Roska, Tamas

    2010-01-01

    This fresh perspective of sensory computing successfully bridges the gap between nanoscale devices and CMOS integrated circuits. Practical and complex algorithms are also discussed, in addition to new developments like the nanoscale antenna.

  4. A complementary metal-oxide-semiconductor compatible monocantilever 12-point probe for conductivity measurements on the nanoscale

    OpenAIRE

    Gammelgaard, Lauge; Bøggild, Peter; Wells, J.W.; Handrup, K.; Hofmann, Ph.; Balslev, M.B.; Hansen, J.E.; Petersen, P.R.E

    2008-01-01

    We present a complementary metal-oxide-semiconductor compatible, nanoscale 12-point-probe based on TiW electrodes placed on a SiO2 monocantilever. Probes are mass fabricated on Si wafers by a combination of electron beam and UV lithography, realizing TiW electrode tips with a width down to 250 nm and a probe pitch of 500 nm. In-air four-point measurements have been performed on indium tin oxide, ruthenium, and titanium-tungsten, showing good agreement with values obtained by other four-point ...

  5. Novel Route to Fabrication of Metal-Sandwiched Nanoscale Tapered Structures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yang; YU Da-Peng

    2009-01-01

    Tapered dielectric structures in metal have exhibited extraordinary performance in both surface plasmon polariton (SPP) waveguiding and SPP focusing.This is crucial to plazmonic research and industrial plasmonic device integration.We present a method that facilitates easy fabrication of smooth-surfaced sub-micron tapered structures in large scale simply with electron beam lithography (EBL).When a PMMA layer is spin-coated on previously-EBL-defined PMMA structures,steep edges can be transformed into a declining slope to form tapered PMMA structures,scaled from 10nm to 1000nm.Despite the simplicity of our method,patterns with PMMA surface smoothness can be well-positioned and replicated in large numbers,which therefore gives scientists easy access to research on the properties of tapered structures.

  6. Performance assessment of nanoscale Schottky MOSFET as resonant tunnelling device: Non-equilibrium Green’s function formalism

    Indian Academy of Sciences (India)

    Zahra Ahangari; Morteza Fathipour

    2013-09-01

    A comprehensive study is performed on the electrical characteristics of Schottky barrier MOSFET (SBMOSFET) in nanoscale regime, by employing the non-equilibrium Green’s function (NEGF) approach. Quantum confinement results in the enhancement of effective Schottky barrier height (SBH). High enough Schottky barriers at the source/drain and the channel form a double barrier profile along the channel that results in the formation of resonance states. We have, for the first time, proposed a resonant tunnelling device based on SBMOSFET in which multiple resonance states are modulated by the gate voltage. Role of essential factors such as temperature, SBH, bias voltage and structural parameters on the feasibility of this device for silicon-based resonant tunnelling applications are extensively studied. Resonant tunnelling appears at low temperatures and low drain voltages and as a result negative differential resistance (NDR) is apparent in the transfer characteristic. Scaling down the gate length to 6 nm increases the peak-to-valley ratio (PVR) of the drain current. As the effective SBH reduces, the curvature of the double barrier profile is gradually diminished. Therefore, multiple resonant states are contributed to the current and consequently resonant tunnelling is smoothed out.

  7. High-field electron transport in nanoscale group-III nitride devices

    Energy Technology Data Exchange (ETDEWEB)

    Komirenko, S.M.; Kim, K.W. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Electrical and Computer Engineering; Kochelap, V.A. [Inst. of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev-28 (Ukraine); Stroscio, M.A. [Army Research Office, Research Triangle Park, NC (United States). Mathematical Sciences Div.

    2001-11-08

    Focusing on the short-size group-III nitride heterostructures, we have developed a model which takes into account main features of transport of electrons injected into a polar semiconductor under high electric fields. The model is based on an exact analytical solution of Boltzmann transport equation. The electron velocity distribution over the device is analyzed at different fields and the basic characteristics of the high-field electron transport are obtained. The critical field for the runaway regime, when electron energies and velocities increase with distance which results in the average velocities higher than the peak velocity in bulk-like samples, is determined. We have found that the runaway electrons are characterized by a distribution function with population inversion. Different nitride-based small-size devices where this effect can have an impact on the device performance are considered. (orig.)

  8. Nanofabrication of Metallic Nanostructures and Integration with Light Detection Devices

    Science.gov (United States)

    Huang, Liang

    Metallic nanostructures have been investigated with various applications especially for integration with light detection devices. The incident light can be manipulated by those nanostructures to enhance light absorption therefor improve device performance. However, previous studies focused on optical design. The electrical properties of these integrated light detection devices have not been fully considered. The photon generated carriers transport and collection are critical for light detection devices as well. An optimized device platform considering from both the optical and electrical aspects to fully utilize these nanostructures is highly desired for future light detection devices. This dissertation targeted on three objectives, beginning with the fabrication process development of various nanostructures on different substrates. High quality nanostructures were achieved with minimum 20nm gap and 45nm line width. The second objective was developing the metallic fishnet nanostructures integrated Schottky contact a-Si solar cell to improve both light absorption and photon generated carrier collection. The fishnet was designed as the light trapping structure and 2D connected top contact to collect carriers. The third objective was developing metallic nanostructures integrated GeSn photodetectors. The H shape nano antennas were integrated on GeSn photodetectors. Multiple resonant absorption peaks at infrared range were observed using spectroscopic ellipsometry. However, there was no obvious photoresponse value improvement of developed solar cells and H shape antennas integrated GeSn photodetectors. For further investigation, interdigitated electrodes integrated GeSn photodetectors were designed. With less carrier transit time, the responsivity value of the integrated Ge0.991Sn0.009 photodetector was 72muA/W at 1.55mum at room temperature which was 6 times higher comparing to device without integration. Meanwhile, with the increased carrier life time by decreasing

  9. Design and Fabrication of Nanoscale IDTs Using Electron Beam Technology for High-Frequency SAW Devices

    Directory of Open Access Journals (Sweden)

    Wei-Che Shih

    2014-01-01

    Full Text Available High-frequency Rayleigh-mode surface acoustic wave (SAW devices were fabricated for 4G mobile telecommunications. The RF magnetron sputtering method was adopted to grow piezoelectric aluminum nitride (AlN thin films on the Si3N4/Si substrates. The influence of sputtering parameters on the crystalline characteristics of AlN thin films was investigated. The interdigital transducer electrodes (IDTs of aluminum (Al were then fabricated onto the AlN surfaces by using the electron beam (e-beam direct write lithography method to form the Al/AlN/Si3N4/Si structured SAW devices. The Al electrodes were adopted owing to its low resistivity, low cost, and low density of the material. For 4G applications in mobile telecommunications, the line widths of 937 nm, 750 nm, 562 nm, and 375 nm of IDTs were designed. Preferred orientation and crystalline properties of AlN thin films were determined by X-ray diffraction using a Siemens XRD-8 with CuKα radiation. Additionally, the cross-sectional images of AlN thin films were obtained by scanning electron microscope. Finally, the frequency responses of high-frequency SAW devices were measured using the E5071C network analyzer. The center frequencies of the high-frequency Rayleigh-mode SAW devices of 1.36 GHz, 1.81 GHz, 2.37 GHz, and 3.74 GHz are obtained. This study demonstrates that the proposed processing method significantly contributes to high-frequency SAW devices for wireless communications.

  10. Verification of redox-processes as switching and retention failure mechanisms in Nb:SrTiO3/metal devices

    Science.gov (United States)

    Baeumer, C.; Raab, N.; Menke, T.; Schmitz, C.; Rosezin, R.; Müller, P.; Andrä, M.; Feyer, V.; Bruchhaus, R.; Gunkel, F.; Schneider, C. M.; Waser, R.; Dittmann, R.

    2016-07-01

    Nanoscale redox reactions in transition metal oxides are believed to be the physical foundation of memristive devices, which present a highly scalable, low-power alternative for future non-volatile memory devices. The interface between noble metal top electrodes and Nb-doped SrTiO3 single crystals may serve as a prominent but not yet well-understood example of such memristive devices. In this report, we will present experimental evidence that nanoscale redox reactions and the associated valence change mechanism are indeed responsible for the resistance change in noble metal/Nb-doped SrTiO3 junctions with dimensions ranging from the micrometer scale down to the nanometer regime. Direct verification of the valence change mechanism is given by spectromicroscopic characterization of switching filaments. Furthermore, it is found that the resistance change over time is driven by the reoxidation of a previously oxygen-deficient region. The retention times of the low resistance states, accordingly, can be dramatically improved under vacuum conditions as well as through the insertion of a thin Al2O3 layer which prevents this reoxidation. These insights finally confirm the resistive switching mechanism at these interfaces and are therefore of significant importance for the study and application of memristive devices based on Nb-doped SrTiO3 as well as systems with similar switching mechanisms.Nanoscale redox reactions in transition metal oxides are believed to be the physical foundation of memristive devices, which present a highly scalable, low-power alternative for future non-volatile memory devices. The interface between noble metal top electrodes and Nb-doped SrTiO3 single crystals may serve as a prominent but not yet well-understood example of such memristive devices. In this report, we will present experimental evidence that nanoscale redox reactions and the associated valence change mechanism are indeed responsible for the resistance change in noble metal/Nb-doped Sr

  11. Cell-directed assembly on an integrated nanoelectronic/nanophotonic device for probing cellular responses on the nanoscale.

    Energy Technology Data Exchange (ETDEWEB)

    Brinker, C. Jeffrey; Dunphy, Darren Robert; Ashley, Carlee E. (University of New Mexico, Albuquerque, NM); Fan, Hongyou; Lopez, DeAnna (University of New Mexico, Albuquerque, NM); Simpson, Regina Lynn; Tallant, David Robert; Burckel, David Bruce; Baca, Helen Kennicott (University of New Mexico, Albuquerque, NM); Carnes, Eric C. (University of New Mexico, Albuquerque, NM); Singh, Seema

    2006-01-01

    Our discovery that the introduction of living cells (Saccharomyces cerevisiae) alters dramatically the evaporation driven self-assembly of lipid-silica nanostructures suggested the formation of novel bio/nano interfaces useful for cellular interrogation at the nanoscale. This one year ''out of the box'' LDRD focused on the localization of metallic and semi-conducting nanocrystals at the fluid, lipid-rich interface between S. cerevisiae and the surrounding phospholipid-templated silica nanostructure with the primary goal of creating Surface Enhanced Raman Spectroscopy (SERS)-active nanostructures and platforms for cellular integration into electrode arrays. Such structures are of interest for probing cellular responses to the onset of disease, understanding of cell-cell communication, and the development of cell-based bio-sensors. As SERS is known to be sensitive to the size and shape of metallic (principally gold and silver) nanocrystals, various sizes and shapes of nanocrystals were synthesized, functionalized and localized at the cellular surface by our ''cell-directed assembly'' approach. Laser scanning confocal microscopy, SEM, and in situ grazing incidence small angle x-ray scattering (GISAXS) experiments were performed to study metallic nanocrystal localization. Preliminary Raman spectroscopy studies were conducted to test for SERS activity. Interferometric lithography was used to construct high aspect ratio cylindrical holes on patterned gold substrates and electro-deposition experiments were performed in a preliminary attempt to create electrode arrays. A new printing procedure was also developed for cellular integration into nanostructured platforms that avoids solvent exposure and may mitigate osmotic stress. Using a different approach, substrates comprised of self-assembled nanoparticles in a phospholipid templated silica film were also developed. When printed on top of these substrates, the cells integrate

  12. Mechanical properties of thin film Parylene-metal-Parylene devices

    Directory of Open Access Journals (Sweden)

    Curtis Dixon Lee

    2015-09-01

    Full Text Available Structures and testing methods for measuring the adhesion strength, minimum bending diameter, and bending fatigue performance of thin film polymer electronic architectures were developed and applied to Parylene-metal-Parylene systems with and without the moisture barrier Al2O3 (deposited using atomic layer deposition (ALD. Parylene-metal-Parylene interfaces had the strongest average peel test strength and Parylene-Parylene interfaces had the weakest peel. Layers of ALD Al2O3 deposited within the device increased the average peel strength for Parylene-Parylene interfaces when combined with silane A-174, but did not increase the Parylene-metal-Parylene interface. Metal traces in the middle of 24 µm thick Parylene-metal-Parylene devices had a minimum bending diameter of ~130 µm before breaking and being measured as an open circuit. The addition of one layer of Al2O3 above the traces allowed them to be completely creased when bent away from the Al2O3 layer without producing an open circuit, but increased the minimum bending diameter to ~450 µm when bent away from the Al2O3. Although fatigue testing produced cracks in all devcies after 100k bends, the insulation of the Parylene-metal-Parylene devices without Al2O3 performed well with electrochemical impedance spectroscopy (EIS showing only small decreases in impedance magnitude and small increases of impedance phase at low frequencies. However, devices with Al2O3 failed during EIS due to Al2O3 being deteriorated by water.

  13. Laser direct writing of micro- and nano-scale medical devices

    OpenAIRE

    Gittard, Shaun D; Narayan, Roger J.

    2010-01-01

    Laser-based direct writing of materials has undergone significant development in recent years. The ability to modify a variety of materials at small length scales and using short production times provides laser direct writing with unique capabilities for fabrication of medical devices. In many laser-based rapid prototyping methods, microscale and submicroscale structuring of materials is controlled by computer-generated models. Various laser-based direct write methods, including selective las...

  14. Micro-/nanoscale multi-field coupling in nonlinear photonic devices

    Science.gov (United States)

    Yang, Qing; Wang, Yubo; Tang, Mingwei; Xu, Pengfei; Xu, Yingke; Liu, Xu

    2017-08-01

    The coupling of mechanics/electronics/photonics may improve the performance of nanophotonic devices not only in the linear region but also in the nonlinear region. This review letter mainly presents the recent advances on multi-field coupling in nonlinear photonic devices. The nonlinear piezoelectric effect and piezo-phototronic effects in quantum wells and fibers show that large second-order nonlinear susceptibilities can be achieved, and second harmonic generation and electro-optic modulation can be enhanced and modulated. Strain engineering can tune the lattice structures and induce second order susceptibilities in central symmetry semiconductors. By combining the absorption-based photoacoustic effect and intensity-dependent photobleaching effect, subdiffraction imaging can be achieved. This review will also discuss possible future applications of these novel effects and the perspective of their research. The review can help us develop a deeper knowledge of the substance of photon-electron-phonon interaction in a micro-/nano- system. Moreover, it can benefit the design of nonlinear optical sensors and imaging devices with a faster response rate, higher efficiency, more sensitivity and higher spatial resolution which could be applied in environmental detection, bio-sensors, medical imaging and so on.

  15. Nanoscale Imaging of Band Gap and Defects in Polycrystalline CdTe Photovoltaic Devices

    Science.gov (United States)

    Zhitenev, Nikolai; Yoon, Yohan; Chae, Jungseok; Katzenmeyer, Aaron; Yoon, Heayoung; An, Sangmin; Shumacher, Joshua; Centrone, Andrea

    To further increase the power efficiency of polycrystalline thin film photovoltaic (PV) technology, a detailed understanding of microstructural properties of the devices is required. In this work, we investigate the microstructure of CdTe PV devices using two optical spectroscopies. Sub-micron thickness lamella samples were cut out from a PV device, either in cross-section or in-plane, by focused ion beam. The first technique is the photothermal induced resonance (PTIR) used to obtain absorption spectra over a broad range of wavelengths. In PTIR, a wavelength tunable pulsed laser is combined with an atomic force microscope to detect the local thermal expansion of lamella CdTe sample induced by light absorption. The second technique based on a near-field scanning optical microscope maps the local absorption at fixed near-IR wavelengths with energies at or below CdTe band-gap energy. The variation of the band gap throughout the CdTe absorber determined from PTIR spectra is ~ 20 meV. Both techniques detect strong spatial variation of shallow defects over different grains. The spatial distribution of mid-gap defects appears to be more uniform. The resolution, the sensitivity and the applicability of these two approaches are compared.

  16. Significant Enhancement of the Adhesion between Metal Films and Polymer Substrates by UV-Ozone Surface Modification in Nanoscale.

    Science.gov (United States)

    Liu, Junshan; He, Licheng; Wang, Liang; Man, Yuncheng; Huang, Luyi; Xu, Zheng; Ge, Dan; Li, Jingmin; Liu, Chong; Wang, Liding

    2016-11-09

    Polymer metallization is extensively used in a variety of micro- and nanosystem technologies. However, the deposited metal film exhibits poor adhesion to polymer substrates, which may cause difficulties in many applications. In this work, ultraviolet (UV)-ozone surface modification is for the first time put forward to enhance the adhesion between metal films and polymer substrates. The adhesion of sputtered Cu films on UV-ozone modified poly(methyl methacrylate) (PMMA) substrates is enhanced by a factor of 6, and that of Au films is improved by a factor of 10. Moreover, metal films on the modified PMMA substrates can withstand a long-time liquid immersion. To understand the mechanism for the adhesion enhancement, the surface modification is studied with contact angle measurements, attenuated total reflection Fourier-transform infrared spectrometry (ATR-FTIR) and atomic force microscopy (AFM). Detailed characterization results indicate that the significant adhesion enhancement is attributed to the increases of both the surface wettability by generating some polar functional groups and the roughness of the surface in nanoscale. To demonstrate this novel polymer metallization method, a 6-in. PMMA chip with arrays of three-electrode electrochemical microsensors is designed and fabricated, and the microsensor exhibits excellent reproducibility, uniformity, and long-term stability.

  17. Wearout Reliability and Intermetallic Compound Diffusion Kinetics of Au and PdCu Wires Used in Nanoscale Device Packaging

    Directory of Open Access Journals (Sweden)

    C. L. Gan

    2013-01-01

    Full Text Available Wearout reliability and diffusion kinetics of Au and Pd-coated Cu (PdCu ball bonds are useful technical information for Cu wire deployment in nanoscale semiconductor device packaging. This paper discusses the HAST (with bias and UHAST (unbiased HAST wearout reliability performance of Au and PdCu wires used in fine pitch BGA packages. In-depth failure analysis has been carried out to identify the failure mechanism under various wearout conditions. Intermetallic compound (IMC diffusion constants and apparent activation energies (Eaa of both wire types were investigated after high temperature storage life test (HTSL. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of PdCu. PdCu wire was found to exhibit equivalent or better wearout reliability margin compared to conventional Au wire bonds. Failure mechanisms of Au, Cu ball bonds post-HAST and UHAST tests are been proposed, and both Au and PdCu IMC diffusion kinetics and their characteristics are discussed in this paper.

  18. Nanoscale relaxation oscillator

    Science.gov (United States)

    Zettl, Alexander K.; Regan, Brian C.; Aloni, Shaul

    2009-04-07

    A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.

  19. Nanoscale structure, dynamics and power conversion efficiency correlations in small molecule and oligomer-based photovoltaic devices

    Directory of Open Access Journals (Sweden)

    Lin X. Chen

    2011-08-01

    Full Text Available Photovoltaic functions in organic materials are intimately connected to interfacial morphologies of molecular packing in films on the nanometer scale and molecular levels. This review will focus on current studies on correlations of nanoscale morphologies in organic photovoltaic (OPV materials with fundamental processes relevant to photovoltaic functions, such as light harvesting, exciton splitting, exciton diffusion, and charge separation (CS and diffusion. Small molecule photovoltaic materials will be discussed here. The donor and acceptor materials in small molecule OPV devices can be fabricated in vacuum-deposited, multilayer, crystalline thin films, or spin-coated together to form blended bulk heterojunction (BHJ films. These two methods result in very different morphologies of the solar cell active layers. There is still a formidable debate regarding which morphology is favored for OPV optimization. The morphology of the conducting films has been systematically altered; using variations of the techniques above, the whole spectrum of film qualities can be fabricated. It is possible to form a highly crystalline material, one which is completely amorphous, or an intermediate morphology. In this review, we will summarize the past key findings that have driven organic solar cell research and the current state-of-the-art of small molecule and conducting oligomer materials. We will also discuss the merits and drawbacks of these devices. Finally, we will highlight some works that directly compare the spectra and morphology of systematically elongated oligothiophene derivatives and compare these oligomers to their polymer counterparts. We hope this review will shed some new light on the morphology differences of these two systems.

  20. Nanoscale structure, dynamics and power conversion efficiency correlations in small molecule and oligomer-based photovoltaic devices.

    Science.gov (United States)

    Szarko, Jodi M; Guo, Jianchang; Rolczynski, Brian S; Chen, Lin X

    2011-01-01

    Photovoltaic functions in organic materials are intimately connected to interfacial morphologies of molecular packing in films on the nanometer scale and molecular levels. This review will focus on current studies on correlations of nanoscale morphologies in organic photovoltaic (OPV) materials with fundamental processes relevant to photovoltaic functions, such as light harvesting, exciton splitting, exciton diffusion, and charge separation (CS) and diffusion. Small molecule photovoltaic materials will be discussed here. The donor and acceptor materials in small molecule OPV devices can be fabricated in vacuum-deposited, multilayer, crystalline thin films, or spin-coated together to form blended bulk heterojunction (BHJ) films. These two methods result in very different morphologies of the solar cell active layers. There is still a formidable debate regarding which morphology is favored for OPV optimization. The morphology of the conducting films has been systematically altered; using variations of the techniques above, the whole spectrum of film qualities can be fabricated. It is possible to form a highly crystalline material, one which is completely amorphous, or an intermediate morphology. In this review, we will summarize the past key findings that have driven organic solar cell research and the current state-of-the-art of small molecule and conducting oligomer materials. We will also discuss the merits and drawbacks of these devices. Finally, we will highlight some works that directly compare the spectra and morphology of systematically elongated oligothiophene derivatives and compare these oligomers to their polymer counterparts. We hope this review will shed some new light on the morphology differences of these two systems.

  1. Investigation on the special Smith-Purcell radiation from a nano-scale rectangular metallic grating

    Science.gov (United States)

    Li, Weiwei; Liu, Weihao; Jia, Qika

    2016-03-01

    The special Smith-Purcell radiation (S-SPR), which is from the radiating eigen modes of a grating, has remarkable higher intensity than the ordinary Smith-Purcell radiation. Yet in previous studies, the gratings were treated as perfect conductor without considering the surface plasmon polaritons (SPPs) which are of significance for the nano-scale gratings especially in the optical region. In present paper, the rigorous theoretical investigations on the S-SPR from a nano-grating with SPPs taken into consideration are carried out. The dispersion relations and radiation characteristics are obtained, and the results are verified by simulations. According to the analyses, the tunable light radiation can be achieved by the S-SPR from a nano-grating, which offers a new prospect for developing the nano-scale light sources.

  2. Analysis and calibration of transient enhanced diffusion for an indium impurity in a nanoscale semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun-Ha; Lee, Hoong-Joo [Sangmyung University, Chonan (Korea, Republic of)

    2005-02-15

    We developed a new systematic calibration procedure which was applied to the prediction of the diffusivity, the segregation, and transient enhanced diffusion (TED) of an indium impurity. The TED of the indium impurity was studied using four different experimental conditions. Although indium is susceptible to TED, rapid thermal annealing (RTA) is effective in suppressing the TED effect and maintaining a steep retrograde profile. Like boron impurities, the indium shows significant oxidation-enhanced diffusion in silicon and has segregation coefficients much less than 1 at the Si/SiO{sub 2} interface. In contrast to boron, the segregation coefficient of indium decreases as the temperature increases. The accuracy of the proposed procedure was validated by using secondary ion mass spectrometry (SIMS) data and by using the 0.13-{mu}m device characteristics, such as V{sub th} and I{sub dsat}, for which the differences between simulation and experiment less than 5 %.

  3. Surface Potential Analysis of Nanoscale Biomaterials and Devices Using Kelvin Probe Force Microscopy

    Directory of Open Access Journals (Sweden)

    Hyungbeen Lee

    2016-01-01

    Full Text Available In recent years, Kelvin probe force microscopy (KPFM has emerged as a versatile toolkit for exploring electrical properties on a broad range of nanobiomaterials and molecules. An analysis using KPFM can provide valuable sample information including surface potential and work function of a certain material. Accordingly, KPFM has been widely used in the areas of material science, electronics, and biomedical science. In this review, we will briefly explain the setup of KPFM and its measuring principle and then survey representative results of various KPFM applications ranging from material analysis to device analysis. Finally, we will discuss some possibilities of KPFM on whether it is applicable to various sensor systems. Our perspective shed unique light on how KPFM can be used as a biosensor as well as equipment to measure electrical properties of materials and to recognize various molecular interactions.

  4. Metallic-like bonding in plasma-born silicon nanocrystals for nanoscale bandgap engineering.

    Science.gov (United States)

    Vach, Holger; Ivanova, Lena V; Timerghazin, Qadir K; Jardali, Fatme; Le, Ha-Linh Thi

    2016-10-27

    Based on ab initio molecular dynamics simulations, we show that small nanoclusters of about 1 nm size spontaneously generated in a low-temperature silane plasma do not possess tetrahedral structures, but are ultrastable. Apparently small differences in the cluster structure result in substantial modifications in their electric, magnetic, and optical properties, without the need for any dopants. Their non-tetrahedral geometries notably lead to electron deficient bonds that introduce efficient electron delocalization that strongly resembles the one of a homogeneous electron gas leading to metallic-like bonding within a semiconductor nanocrystal. As a result, pure hydrogenated silicon clusters that form by self-assembly in a plasma reactor possess optical gaps covering most of the solar spectrum from 1.0 eV to 5.2 eV depending simply on their structure and, in turn, on their degree of electron delocalization. This feature makes them ideal candidates for future bandgap engineering not only for photovoltaics, but also for many nano-electronic devices employing nothing else but silicon and hydrogen atoms.

  5. Direct-Liquid-Evaporation Chemical Vapor Deposition of Nanocrystalline Cobalt Metal for Nanoscale Copper Interconnect Encapsulation.

    Science.gov (United States)

    Feng, Jun; Gong, Xian; Lou, Xiabing; Gordon, Roy G

    2017-03-29

    In advanced microelectronics, precise design of liner and capping layers become critical, especially when it comes to the fabrication of Cu interconnects with dimensions lower than its mean free path. Herein, we demonstrate that direct-liquid-evaporation chemical vapor deposition (DLE-CVD) of Co is a promising method to make liner and capping layers for nanoscale Cu interconnects. DLE-CVD makes pure, smooth, nanocrystalline, and highly conformal Co films with highly controllable growth characteristics. This process allows full Co encapsulation of nanoscale Cu interconnects, thus stabilizing Cu against diffusion and electromigration. Electrical measurements and high-resolution elemental imaging studies show that the DLE-CVD Co encapsulation layer can improve the reliability and thermal stability of Cu interconnects. Also, with the high conductivity of Co, the DLE-CVD Co encapsulation layer have the potential to further decrease the power consumption of nanoscale Cu interconnects, paving the way for Cu interconnects with higher efficiency in future high-end microelectronics.

  6. Nanoscale discharge electrode for minimizing ozone emission from indoor corona devices.

    Science.gov (United States)

    Bo, Zheng; Yu, Kehan; Lu, Ganhua; Mao, Shun; Chen, Junhong; Fan, Fa-Gung

    2010-08-15

    Ground-level ozone emitted from indoor corona devices poses serious health risks to the human respiratory system and the lung function. Federal regulations call for effective techniques to minimize the indoor ozone production. In this work, stable atmospheric corona discharges from nanomaterials are demonstrated using horizontally suspended carbon nanotubes (CNTs) as the discharge electrode. Compared with the conventional discharges employing micro- or macroscale electrodes, the corona discharge from CNTs could initiate and operate at a much lower voltage due to the small electrode diameter, and is thus energy-efficient. Most importantly, the reported discharge is environmentally friendly since no ozone (below the detection limit of 0.5 ppb) was detected for area current densities up to 0.744 A/m(2) due to the significantly reduced number of electrons and plasma volume generated by CNT discharges. The resulting discharge current density depends on the CNT loading. Contrary to the conventional wisdom, negative CNT discharges should be used to enhance the current density owing to the efficient field emission of electrons from the CNT surface.

  7. Nanoscale design of multifunctional organic layers for low-power high-density memory devices.

    Science.gov (United States)

    Nougaret, Laurianne; Kassa, Hailu G; Cai, Ronggang; Patois, Tilia; Nysten, Bernard; van Breemen, Albert J J M; Gelinck, Gerwin H; de Leeuw, Dago M; Marrani, Alessio; Hu, Zhijun; Jonas, Alain M

    2014-04-22

    We demonstrate the design of a multifunctional organic layer by the rational combination of nanosized regions of two functional polymers. Instead of relying on a spontaneous and random phase separation process or on the tedious synthesis of block copolymers, the method involves the nanomolding of a first component, followed by the filling of the resulting open spaces by a second component. We apply this methodology to fabricate organic nonvolatile memory diodes of high density. These are built by first creating a regular array of ferroelectric nanodots by nanoimprint lithography, followed by the filling of the trenches separating the ferroelectric nanodots with a semiconducting polymer. The modulation of the current in the semiconductor by the polarization state of the ferroelectric material is demonstrated both at the scale of a single semiconductor channel and in a microscopic device measuring about 80,000 channels in parallel, for voltages below ca. 2 V. The fabrication process, which combines synergetically orthogonal functional properties with a fine control over their spatial distribution, is thus demonstrated to be efficient over large areas.

  8. The bulk photovoltaic effect as a platform for ultrafast, nanoscale photosensitive devices

    Science.gov (United States)

    Young, Steve

    2017-05-01

    The bulk photovoltaic effect refers to the generation of photocurrents and photovoltages in bulk single-phase materials. It requires only that the material possess broken inversion symmetry, and occurs due a unique mechanism known as "shift current." Discovered over a half-century ago, it received little attention decades due to extremely poor observed efficiency. However, in recent years, it has been both theoretically and experimentally investigated in a variety of new systems and materials, and significant improvements in performance have been achieved. In this talk, I will provide a brief overview of the physics of the bulk photovoltaic effect and survey the experimental and theoretical advances that have been made in its understanding and optimization. I will cover in detail the unique properties of the bulk photovoltaic effect that distinguish it from conventional photovoltaic effects, including photovoltages substantially exceeding the material's band gap, response amplitudes and directions that can depend on both photon energy and polarization, and response that occurs on ultrafast timescales. Finally, I will explore the potential for these features to enable novel and improved photosensitive devices, especially in combination with other functional materials.

  9. Nanoscale thermal probing

    Directory of Open Access Journals (Sweden)

    Yanan Yue

    2012-03-01

    Full Text Available Nanoscale novel devices have raised the demand for nanoscale thermal characterization that is critical for evaluating the device performance and durability. Achieving nanoscale spatial resolution and high accuracy in temperature measurement is very challenging due to the limitation of measurement pathways. In this review, we discuss four methodologies currently developed in nanoscale surface imaging and temperature measurement. To overcome the restriction of the conventional methods, the scanning thermal microscopy technique is widely used. From the perspective of measuring target, the optical feature size method can be applied by using either Raman or fluorescence thermometry. The near-field optical method that measures nanoscale temperature by focusing the optical field to a nano-sized region provides a non-contact and non-destructive way for nanoscale thermal probing. Although the resistance thermometry based on nano-sized thermal sensors is possible for nanoscale thermal probing, significant effort is still needed to reduce the size of the current sensors by using advanced fabrication techniques. At the same time, the development of nanoscale imaging techniques, such as fluorescence imaging, provides a great potential solution to resolve the nanoscale thermal probing problem.

  10. Monitoring the dissolution process of metals in the gas phase: reactions of nanoscale Al and Ga metal atom clusters and their relationship to similar metalloid clusters.

    Science.gov (United States)

    Burgert, Ralf; Schnöckel, Hansgeorg

    2008-05-14

    in order to show that in this cluster only the central naked metal atoms are oxidized, and a smaller metalloid cluster results containing the entire protecting shell as the primary cluster. All the experimental results, supported by quantum chemical calculations, give a rough idea about the complex reaction cascades which occur during the dissolution and formation of metals. Furthermore, these results cast a critical light on many simplifying and generalizing rules in order to understand the bonding and structure of metal clusters. Finally, the experiments and some recent results provided by physical measurements on a crystalline Ga(84) compound build a bridge to nanoscience; i.e. they may be a challenge for chemistry in the next decades, since it has been shown that only with a perfect orientation of nanoscale metal clusters, e.g. in a crystal, can novel, unexpected properties (e.g. superconducting nanoscale materials) be obtained.

  11. Simulation of self-organized waveguides for self-aligned coupling between micro- and nano-scale devices

    Science.gov (United States)

    Yoshimura, Tetsuzo

    2015-05-01

    We propose an optical coupling technique based on the reflective self-organized lightwave network (R-SOLNET), where optical devices with different core sizes are connected, for nano-scale-waveguide-based optical interconnects. Growth of R-SOLNET between a 3-μm-wide waveguide and a 600-nm-wide waveguide, on the core edge of which a luminescent target has been deposited, is simulated by the finite-difference time-domain method. The two waveguides are placed with gap distances ranging from 16 to 64 μm in a photopolymer with a refractive index that increases upon exposure to a write beam and luminescence. When a 400 nm wavelength write beam is introduced from the micro-scale waveguide, 470 nm luminescence is generated from the target. In the area where the write beam and the luminescence overlap, the refractive index increases rapidly. The write beam and the luminescence thus attract each other to merge into one through the self-focusing, forming a self-aligned coupling waveguide of R-SOLNET with a coupling loss of 1.5-1.8 dB, even when a lateral misalignment of 600 nm exists between them. This indicates that the R-SOLNET can be used as an optical solder to connect a micro-scale waveguide to a nano-scale waveguide. The optimum writing time required to attain the minimum coupling loss increases with increasing lateral misalignment. The dependence of the optimum writing time on the misalignment is reduced with increasing gap distance, and it almost vanishes when the distance is 64 μm, enabling unmonitored optical solder formation. R-SOLNET utilizing the two-photon photochemistry is briefly described as the next-generation SOLNET.

  12. Noble metal nanowires: from plasmon waveguides to passive and active devices.

    Science.gov (United States)

    Lal, Surbhi; Hafner, Jason H; Halas, Naomi J; Link, Stephan; Nordlander, Peter

    2012-11-20

    Using chemical synthesis, researchers can produce noble metal nanowires with highly regular, crystalline properties unachievable by alternative, top-down nanofabrication methods. Sitting at the intersection of nanochemistry and nanooptics, noble metal nanowires have generated intense and growing research interest. These nanostructures combine subwavelength transverse dimensions (50-100 nm) and longitudinal dimensions that can reach tens of micrometers or more, which makes them an ideal platform to launch surface plasmon waves by direct illumination of one end of the structure. Because of this property, researchers are using noble metal nanowires as a tool for fundamental studies of subwavelength plasmon-based optics and the properties of surface plasmon guided wave propagation in highly confined geometries below the classical optical diffraction limit. In this Account, we review some of the recent developments in plasmonic nanowire fabrication, nanowire plasmon imaging, and nanowire optical components and devices. The addition of an adjacent nanowire, substrate, or other symmetry-breaking defect can enable the direct coupling of light to and from free space to the guided waves on a nanowire structure. Such structures lead to more complex nanowire-based geometries with multiple optical inputs and outputs. Additional nanowire imaging methods are also possible: plasmon propagation on nanowires produces intense near-field diffraction, which can induce fluorescence in nearby quantum dots or photobleach adjacent molecules. When the nanowire is deposited on a dielectric substrate, the plasmon propagation along chemically synthesized nanowires exceeds 10 μm, which makes these structures useful in nonlocal applications such as remote surface-enhanced Raman spectroscopy (SERS) sensing. Nanowires can be used as passive optical devices, which include, for example, polarization manipulators, linear polarization rotators, or even broadband linear-to-circular polarization

  13. Nanoscale Devices for Rectification of High Frequency Radiation from the Infrared through the Visible: A New Approach

    Directory of Open Access Journals (Sweden)

    N. M. Miskovsky

    2012-01-01

    Full Text Available We present a new and viable method for optical rectification. This approach has been demonstrated both theoretically and experimentally and is the basis fot the development of devices to rectify radiation through the visible. This technique for rectification is based not on conventional material or temperature asymmetry as used in MIM (metal/insulator/metal or Schottky diodes, but on a purely sharp geometric property of the antenna. This sharp “tip” or edge with a collector anode constitutes a tunnel junction. In these devices the rectenna (consisting of the antenna and the tunnel junction acts as the absorber of the incident radiation and the rectifier. Using current nanofabrication techniques and the selective atomic layer deposition (ALD process, junctions of 1 nm can be fabricated, which allow for rectification of frequencies up to the blue portion of the spectrum. To assess the viability of our approach, we review the development of nanoantenna structures and tunnel junctions capable of operating in the visible region. In addition, we review the detailed process of rectification and present methodologies for analysis of diode data. Finally, we present operational designs for an optical rectenna and its fabrication and discuss outstanding problems and future work.

  14. Hollow/porous nanostructures derived from nanoscale metal-organic frameworks towards high performance anodes for lithium-ion batteries

    Science.gov (United States)

    Hu, Lin; Chen, Qianwang

    2014-01-01

    Lithium-ion batteries (LIBs), owing to their high energy density, light weight, and long cycle life, have shown considerable promise for storage devices. The successful utilization of LIBs depends strongly on the preparation of nanomaterials with outstanding lithium storage properties. Recent progress has demonstrated that hollow/porous nanostructured oxides are very attractive candidates for LIBs anodes due to their high storage capacities. Here, we aim to provide an overview of nanoscale metal-organic frameworks (NMOFs)-templated synthesis of hollow/porous nanostructured oxides and their LIBs applications. By choosing some typical NMOFs as examples, we present a comprehensive summary of synthetic procedures for nanostructured oxides, such as binary, ternary and composite oxides. Hollow/porous structures are readily obtained due to volume loss and release of internally generated gas molecules during the calcination of NMOFs in air. Interestingly, the NMOFs-derived hollow/porous structures possess several special features: pores generated from gas molecules release will connect to each other, which are distinct from ``dead pores'' pore size often appears to be <10 nm; in terms of surface chemistry, the pore surface is hydrophobic. These structural features are believed to be the most critical factors that determine LIBs' performance. Indeed, it has been shown that these NMOFs-derived hollow/porous oxides exhibit excellent electrochemical performance as anode materials for LIBs, including high storage capacity, good cycle stability, and so on. For example, a high charge capacity of 1465 mA h g-1 at a rate of 300 mA g-1 was observed after 50 cycles for NMOFs-derived Co3O4 porous nanocages, which corresponds to 94.09% of the initial capacity (1557 mA h g-1), indicating excellent stability. The capacity of NMOFs-derived Co3O4 is higher than that of other Co3O4 nanostructures obtained by a conventional two-step route, including nanosheets (1450 mA h g-1 at 50 mA g-1

  15. Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars.

    Science.gov (United States)

    Nandy, Suman; Gonçalves, Gonçalo; Pinto, Joana Vaz; Busani, Tito; Figueiredo, Vitor; Pereira, Luís; Paiva Martins, Rodrigo Ferrão; Fortunato, Elvira

    2013-12-07

    The present work focuses on a qualitative analysis of localised I-V characteristics based on the nanostructure morphology of highly dense arrays of p-type NiO nano-pillars (NiO-NPs). Vertically aligned NiO-NPs have been grown on different substrates by using a glancing angle deposition (GLAD) technique. The preferred orientation of as grown NiO-NPs was controlled by the deposition pressure. The NiO-NPs displayed a polar surface with a microscopic dipole moment along the (111) plane (Tasker's type III). Consequently, the crystal plane dependent surface electron accumulation layer and the lattice disorder at the grain boundary interface showed a non-uniform current distribution throughout the sample surface, demonstrated by a conducting AFM technique (c-AFM). The variation in I-V for different points in a single current distribution grain (CD-grain) has been attributed to the variation of Schottky barrier height (SBH) at the metal-semiconductor (M-S) interface. Furthermore, we observed that the strain produced during the NiO-NPs growth can modulate the SBH. Inbound strain acts as an external field to influence the local electric field at the M-S interface causing a variation in SBH with the NPs orientation. This paper shows that vertical arrays of NiO-NPs are potential candidates for nanoscale devices because they have a great impact on the local current transport mechanism due to its nanostructure morphology.

  16. Fabrication and properties of nanoscale multiferroic heterostructures for application in magneto-electric random access memory (MERAM) devices

    Science.gov (United States)

    Kim, Gunwoo

    Magnetoelectric random access memory (MERAM) has emerged as a promising new class of non-volatile solid-state memory device. It offers nondestructive reading along with low power consumption during the write operation. A common implementation of MERAM involves use of multiferroic tunneling junctions (MFTJs), which besides offering non-volatility are both electrically and magnetically tunable. Fundamentally, a MFTJ consists of a heterostructure of an ultrathin multiferroic or ferroelectric material as the active tunneling barrier sandwiched between ferromagnetic electrodes. Thereby, the MFTJ exhibits both tunnel electroresistance (TER) and tunnel magnetoresistance (TMR) effects with application of an electric and magnetic field, respectively. In this thesis work, we have developed two-dimensional (2D) thin-film multiferroic heterostructure METJ prototypes consisting of ultrathin ferroelectric BaTiO3 (BTO) layer and a conducting ferromagnetic La0.67Sr 0.33MnO3 (LSMO) electrode. The heteroepitaxial films are grown using the pulsed laser deposition (PLD) technique. This oxide heterostructure offers the opportunity to study the nano-scale details of the tunnel electroresistance (TER) effect using scanning probe microscopy techniques. We performed the measurements using the MFP-3D (Asylum Research) scanning probe microscope. The ultrathin BTO films (1.2-2.0 nm) grown on LSMO electrodes display both ferro- and piezo-electric properties and exhibit large tunnel resistance effect. We have explored the growth and properties of one-dimensional (1D) heterostructures, referred to as multiferoric nanowire (NW) heterostructures. The ferromagnetic/ferroelectric composite heterostructures are grown as sheath layers using PLD on lattice-matched template NWs, e.g. MgO, that are deposited by chemical vapor deposition utilizing the vapor-liquid-solid (VLS) mechanism. The one-dimensional geometry can substantially overcome the clamping effect of the substrate present in two

  17. Some effects of temperature on multiple column metal oxide devices

    Energy Technology Data Exchange (ETDEWEB)

    Kresge, J.S.; Lambert, S.R.; Sakshaug, E.C. [Power Technologies, Inc., Schenectady, NY (United States); Porter, J.W. [Electric Power Research Inst., Palo Alto, CA (United States)

    1995-07-01

    Metal oxide elements are capable of dissipating considerable energy in terms of joules per cubic centimeter or joules per gram, and elements of reasonable size are capable of discharging the energy associated with most surge arrester applications. Surge arresters designed using metal oxide elements have been in service since 1976. However, a single column consisting of elements of usual diameter is not capable of discharging a long, 500-kV or 800-kV transmission line under all of the switching conditions generally considered; therefore, metal oxide arresters for application at these voltages are usually designed with two columns of elements in parallel. Furthermore, devices for series capacitors protection or protection of valves and filters in dc converter stations and similar applications are often required to discharge several tens of times more energy than required by station applications, and are hence designed using several columns of elements in parallel. The objective of this paper is to describe some of the effects of temperature on the operation of parallel multiple column devices.

  18. Rapid magnetic removal of aqueous heavy metals and their relevant mechanisms using nanoscale zero valent iron (nZVI) particles.

    Science.gov (United States)

    Huang, Pengpeng; Ye, Zhengfang; Xie, Wuming; Chen, Qi; Li, Jing; Xu, Zhencheng; Yao, Maosheng

    2013-08-01

    Much work is devoted to heavy metal sorption, reduction and relevant mechanisms by nanoscale zero valent iron (nZVI) particle, but fewer studies utilize its magnetic properties in aqueous metal removals. Here, we have investigated the use of nZVI particles both electrosprayed (E-nZVI) and non-electrosprayed (NE-nZVI) with different concentration levels (0.186-1.86 mg/mL) in removing aqueous Cd(II), Cr(IV), and Pb(II) through the magnetic separation means. The effects of the reaction time (5-20 min) and magnetic treatment time (1-30 min) on relevant magnetic removal efficiencies were studied. Metal ion concentration was analyzed using inductively coupled plasma (ICP), and the magnetically obtained metal-nZVI mixtures were further analyzed using X-ray photoelectron spectroscopy (XPS). Results showed that the magnetic removal efficiencies of heavy metals varied with the metal species, nZVI loading, reaction and magnetic separation time. In most cases, use of 1.5 mg/mL E-nZVI or NE-nZVI resulted in removal efficiencies of more than 80% for Pb(II), Cd(II), and Cr(IV). Increasing the magnetic treatment time from 1 to 20 min was shown to lead to ≈ 20% increase in Pb(II) removal efficiency, but no improvements for Cd(II) and Cr(IV). In contrast, increasing the reaction time decreased the Pb(II) removal efficiency, yet no effects observed for Cd(II) and Cr(IV). In general, 1 min reaction and 5 min magnetic treatment were found sufficient to achieve considerable heavy metal removals. For comparable efficiencies, use of magnetic method could significantly reduce nZVI loading. XPS analysis results indicated that atomic percentages of O 1s, Fe 2p, Cd 3d, Pb 4f and Cr 2p varied with metal exposures. Different from Cd(II) and Cr(IV), aqueous iron ions might be possibly present when treating Pb(II). This study demonstrated a rapid heavy metal removal method using the magnetic property of nZVI particles, while contributing to understanding of the relevant removal mechanisms.

  19. Using mathematical models to understand the effect of nanoscale roughness on protein adsorption for improving medical devices

    Directory of Open Access Journals (Sweden)

    Ercan B

    2013-09-01

    Full Text Available Batur Ercan,1 Dongwoo Khang,2 Joseph Carpenter,3 Thomas J Webster1 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2School of Materials Science and Engineering and Center for PRC and RIGET, Gyeongsang National University, Jinju, South Korea; 3School of Medicine, Stanford University, Stanford, CA, USA Abstract: Surface roughness and energy significantly influence protein adsorption on to biomaterials, which, in turn, controls select cellular adhesion to determine the success and longevity of an implant. To understand these relationships at a fundamental level, a model was originally proposed by Khang et al to correlate nanoscale surface properties (specifically, nanoscale roughness and energy to protein adsorption, which explained the greater cellular responses on nanostructured surfaces commonly reported in the literature today. To test this model for different surfaces from what was previously used to develop that model, in this study we synthesized highly ordered poly(lactic-co-glycolic acid surfaces of identical chemistry but altered nanoscale surface roughness and energy using poly(dimethylsiloxane molds of polystyrene beads. Fibronectin and collagen type IV adsorption studies showed a linear adsorption behavior as the surface nanoroughness increased. This supported the general trends observed by Khang et al. However, when fitting such data to the mathematical model established by Khang et al, a strong correlation did not result. Thus, this study demonstrated that the equation proposed by Khang et al to predict protein adsorption should be modified to accommodate for additional nanoscale surface property contributions (ie, surface charge to make the model more accurate. In summary, results from this study provided an important step in developing future mathematical models that can correlate surface properties (such as nanoscale roughness and surface energy to initial protein adsorption events important to

  20. Synthetic Fabrication of Nanoscale MoS2-Based Transition Metal Sulfides

    Directory of Open Access Journals (Sweden)

    Jikang Yuan

    2010-01-01

    Full Text Available Transition metal sulfides are scientifically and technologically important materials. This review summarizes recent progress on the synthetic fabrication of transition metal sulfides nanocrystals with controlled shape, size, and surface functionality. Special attention is paid to the case of MoS2 nanoparticles, where organic (surfactant, polymer, inorganic (support, promoter, doping compounds and intercalation chemistry are applied.

  1. Topology optimization of metallic devices for microwave applications

    DEFF Research Database (Denmark)

    Aage, Niels; Mortensen, Asger; Sigmund, Ole

    2010-01-01

    In electromagnetic optimization problems of metallic radio-frequency devices, such as antennas and resonators for wireless energy transfer, the volumetric distribution of good conductors, e.g. copper, has been known to cause numerical bottlenecks. In finite element analysis the limiting factor...... is the skin depth, which calls for highly refined meshing in order to capture the physics. The skin depth problem has therefore prohibited the application of topology optimization to this class of problem. We present a design parameterization that remedies these numerical issues, by the interpolation...

  2. Synthesis of Nanoscale Heterostructures Comprised of Metal Nanowires, Carbon Nanotubes, and Metal Nanoparticles: Investigation of Their Structure and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Nitin Chopra

    2015-01-01

    Full Text Available One-dimensional nanoscale heterostructures comprised of multisegment gold-nickel nanowires, carbon nanotube, and nickel nanoparticles were fabricated in a unique approach combining top-down and bottom-up assembly methods. Porous alumina template was utilized for sequential electrodeposition of gold and nickel nanowire segments. This was followed by chemical vapor deposition growth of carbon nanotubes on multisegment gold-nickel nanowires, where nickel segment also acted as a carbon nanotube growth catalyst. The aligned arrays of these gold-nickel-carbon nanotube heterostructures were released from porous alumina template and then subjected to wet-chemical process to be decorated with nickel/nickel oxide core/shell nanoparticles. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were utilized for morphology, interface, defect, and structure characterization. The electrochemical performance of these heterostructures was studied using cyclic voltammetry method and the specific capacitance of various heterostructures was estimated and compared.

  3. In situ electron microscopy studies of electromechanical behavior in metals at the nanoscale using a novel microdevice-based system

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Wonmo, E-mail: wonmo.kang.ctr.ks@nrl.navy.mil; Beniam, Iyoel; Qidwai, Siddiq M. [Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-09-15

    Electrically assisted deformation (EAD) is an emerging technique to enhance formability of metals by applying an electric current through them. Despite its increasing importance in manufacturing applications, there is still an unresolved debate on the nature of the fundamental deformation mechanisms underlying EAD, mainly between electroplasticity (non-thermal effects) and resistive heating (thermal effects). This status is due to two critical challenges: (1) a lack of experimental techniques to directly observe fundamental mechanisms of material deformation during EAD, and (2) intrinsic coupling between electric current and Joule heating giving rise to unwanted thermally activated mechanisms. To overcome these challenges, we have developed a microdevice-based electromechanical testing system (MEMTS) to characterize nanoscale metal specimens in transmission electron microscopy (TEM). Our studies reveal that MEMTS eliminates the effect of Joule heating on material deformation, a critical advantage over macroscopic experiments, owing to its unique scale. For example, a negligible change in temperature (<0.02 °C) is predicted at ∼3500 A/mm{sup 2}. Utilizing the attractive features of MEMTS, we have directly investigated potential electron-dislocation interactions in single crystal copper (SCC) specimens that are simultaneously subjected to uniaxial loading and electric current density up to 5000 A/mm{sup 2}. Our in situ TEM studies indicate that for SCC, electroplasticity does not play a key role as no differences in dislocation activities, such as depinning and movement, are observed.

  4. In situ electron microscopy studies of electromechanical behavior in metals at the nanoscale using a novel microdevice-based system.

    Science.gov (United States)

    Kang, Wonmo; Beniam, Iyoel; Qidwai, Siddiq M

    2016-09-01

    Electrically assisted deformation (EAD) is an emerging technique to enhance formability of metals by applying an electric current through them. Despite its increasing importance in manufacturing applications, there is still an unresolved debate on the nature of the fundamental deformation mechanisms underlying EAD, mainly between electroplasticity (non-thermal effects) and resistive heating (thermal effects). This status is due to two critical challenges: (1) a lack of experimental techniques to directly observe fundamental mechanisms of material deformation during EAD, and (2) intrinsic coupling between electric current and Joule heating giving rise to unwanted thermally activated mechanisms. To overcome these challenges, we have developed a microdevice-based electromechanical testing system (MEMTS) to characterize nanoscale metal specimens in transmission electron microscopy (TEM). Our studies reveal that MEMTS eliminates the effect of Joule heating on material deformation, a critical advantage over macroscopic experiments, owing to its unique scale. For example, a negligible change in temperature (<0.02 °C) is predicted at ∼3500 A/mm(2). Utilizing the attractive features of MEMTS, we have directly investigated potential electron-dislocation interactions in single crystal copper (SCC) specimens that are simultaneously subjected to uniaxial loading and electric current density up to 5000 A/mm(2). Our in situ TEM studies indicate that for SCC, electroplasticity does not play a key role as no differences in dislocation activities, such as depinning and movement, are observed.

  5. In situ electron microscopy studies of electromechanical behavior in metals at the nanoscale using a novel microdevice-based system

    Science.gov (United States)

    Kang, Wonmo; Beniam, Iyoel; Qidwai, Siddiq M.

    2016-09-01

    Electrically assisted deformation (EAD) is an emerging technique to enhance formability of metals by applying an electric current through them. Despite its increasing importance in manufacturing applications, there is still an unresolved debate on the nature of the fundamental deformation mechanisms underlying EAD, mainly between electroplasticity (non-thermal effects) and resistive heating (thermal effects). This status is due to two critical challenges: (1) a lack of experimental techniques to directly observe fundamental mechanisms of material deformation during EAD, and (2) intrinsic coupling between electric current and Joule heating giving rise to unwanted thermally activated mechanisms. To overcome these challenges, we have developed a microdevice-based electromechanical testing system (MEMTS) to characterize nanoscale metal specimens in transmission electron microscopy (TEM). Our studies reveal that MEMTS eliminates the effect of Joule heating on material deformation, a critical advantage over macroscopic experiments, owing to its unique scale. For example, a negligible change in temperature (<0.02 °C) is predicted at ˜3500 A/mm2. Utilizing the attractive features of MEMTS, we have directly investigated potential electron-dislocation interactions in single crystal copper (SCC) specimens that are simultaneously subjected to uniaxial loading and electric current density up to 5000 A/mm2. Our in situ TEM studies indicate that for SCC, electroplasticity does not play a key role as no differences in dislocation activities, such as depinning and movement, are observed.

  6. Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Fei, E-mail: paper_mail@126.com [Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Yang, Baochun; Cai, Jing [Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Jiang, Yaodong [Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Xu, Jun [Department of Health Economy Administration, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Wang, Shan [Department of Pharmacy, Winthrop University Hospital, Mineola, NY 11501 (United States)

    2014-04-01

    Highlights: • Metal-organic frameworks (MOFs) represent a newborn family of hybrid materials. • MOFs have already shown promise in a number of biological applications. • The biological applications of MOFs raise concerns for potential cytotoxicity. • Substantial information about MOF's neurotoxicity is still quite scarce. • This study reveals for the first time the interaction of MOFs with neural cells. - Abstract: Metal-organic frameworks (MOFs) possess unique properties desirable for delivery of drugs and gaseous therapeutics, but their uncharacterized interactions with cells raise increasing concerns of their safety in such biomedical applications. We evaluated the adverse effects of zinc nanoscale MOFs on the cell morphology, cytoskeleton, cell viability and expression of neurotrophin signaling pathway-associated GAP-43 protein in rat pheochromocytoma PC12 cells. At the concentration of 25 μg/ml, zinc MOFs did not significantly affect morphology, viability and membrane integrity of the cells. But at higher concentrations (over 100 μg/ml), MOFs exhibited a time- and concentration-dependent cytotoxicity, indicating their entry into the cells via endocytosis where they release Zn{sup 2+} into the cytosol to cause increased intracellular concentration of Zn{sup 2+}. We demonstrated that the toxicity of MOFs was associated with a disrupted cellular zinc homeostasis and down-regulation of GAP-43 protein, which might be the underlying mechanism for the improved differentiation in PC12 cells. These findings highlight the importance of cytotoxic evaluation of the MOFs before their biomedical application.

  7. Transtion metal oxides for solar water splitting devices

    Science.gov (United States)

    Smith, Adam M.

    Although the terrestrial flux of solar energy is enough to support human endeavors, storage of solar energy remains a significant challenge to large-scale implementation of solar energy production. One route to energy storage involves the capture and conversion of sunlight to chemical species such as molecular hydrogen and oxygen via water splitting devices. The oxygen evolution half-reaction particularly suffers from large kinetic overpotentials. Additionally, a photoactive material that exhibits stability in oxidizing conditions present during oxygen evolution represents a unique challenge for devices. These concerns can be potentially addressed with a metal oxide photoanode coupled with efficient water oxidation electrocatalysts. Despite decades of research, structure-composition to property relationships are still needed for the design of metal oxide oxygen evolution materials. This dissertation investigates transition metal oxide materials for the oxygen evolution portion of water splitting devices. Chapter I introduces key challenges for solar driven water splitting. Chapter II elucidates the growth mechanism of tungsten oxide (WOX) nanowires (NWs), a proposed photoanode material for water splitting. Key findings include (1) a planar defect-driven pseudo-one-dimensional growth mechanism and (2) morphological control through the supersaturation of vapor precursors. Result 1 is significant as it illustrates that common vapor-phase syntheses of WOX NWs depend on the formation of planar defects through NWs, which necessitates reconsideration of WOX as a photoanode. Chapter III presents work towards (1) single crystal WOX synthesis and characterization and (2) WOX NW device fabrication. Chapter IV makes use of the key result that WOX NWs are defect rich and therefore conductive in order to utilize them as a catalyst scaffold for oxygen evolution in acidic media. Work towards utilizing NW scaffolds include key results such as stability under anodic potentials and

  8. A microfluidic device for real-time monitoring of Bacillus subtilis bacterial spores during germination based on non-specific physicochemical interactions on the nanoscale level.

    Science.gov (United States)

    Zabrocka, L; Langer, K; Michalski, A; Kocik, J; Langer, J J

    2015-01-07

    A microfluidic device for studies on the germination of bacterial spores (e.g. Bacillus subtilis) based on non-specific interactions on the nanoscale is presented. A decrease in the population of spores during germination followed by the appearance of transition forms and an increase in the number of vegetative cells can be registered directly and simultaneously by using the microfluidic device, which is equipped with a conductive polymer layer (polyaniline) in the form of a nano-network. The lab-on-a-chip-type device, operating in a continuous flow regime, allows monitoring of germination of bacterial spores and analysis of the process in detail. The procedure is fast and accurate enough for quantitative real-time monitoring of the main steps of germination, including final transformation of the spores into vegetative cells. All of this is done without the use of biomarkers or any bio-specific materials, such as enzymes, antibodies and aptamers, and is simply based on an analysis of physicochemical interactions on the nanoscale level.

  9. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

    OpenAIRE

    Vander Wal, Randy L.; Berger, Gordon M.; Kulis, Michael J.; Hunter, Gary W; Laura Evans; Xu, Jennifer C.

    2009-01-01

    A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing ...

  10. Modeling nanoscale gas sensors under realistic conditions: Computational screening of metal-doped carbon nanotubes

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Mowbray, Duncan; Thygesen, Kristian Sommer

    2010-01-01

    We use computational screening to systematically investigate the use of transition-metal-doped carbon nanotubes for chemical-gas sensing. For a set of relevant target molecules (CO, NH3, and H2S) and the main components of air (N2, O2, and H2O), we calculate the binding energy and change...

  11. Anomalous electron transport in metal/carbon multijunction devices by engineering of the carbon thickness and selecting metal layer

    Science.gov (United States)

    Dwivedi, Neeraj; Dhand, Chetna; Rawal, Ishpal; Kumar, Sushil; Malik, Hitendra K.; Lakshminarayanan, Rajamani

    2017-06-01

    A longstanding concern in the research of amorphous carbon films is their poor electrical conductivity at room temperature which constitutes a major barrier for the development of cost effective electronic and optoelectronic devices. Here, we propose metal/carbon hybrid multijunction devices as a promising facile way to overcome room temperature electron transport issues in amorphous carbon films. By the tuning of carbon thickness and swapping metal layers, we observe giant (upto ˜7 orders) reduction of electrical resistance in metal/carbon multijunction devices with respect to monolithic amorphous carbon device. We engineer the maximum current (electrical resistance) from about 10-7 to 10-3 A (˜107 to 103 Ω) in metal (Cu or Ti)/carbon hybrid multijunction devices with a total number of 10 junctions. The introduction of thin metal layers breaks the continuity of relatively higher resistance carbon layer as well as promotes the nanostructuring of carbon. These contribute to low electrical resistance of metal/carbon hybrid multijunction devices, with respect to monolithic carbon device, which is further reduced by decreasing the thickness of carbon layers. We also propose and discuss equivalent circuit model to explain electrical resistance in monolithic carbon and metal/carbon multijunction devices. Cu/carbon multijunction devices display relatively better electrical transport than Ti/carbon devices owing to low affinity of Cu with carbon that restricts carbide formation. We also observe that in metal/carbon multijunction devices, the transport mechanism changes from Poole-Frenkel/Schottky model to the hopping model with a decrease in carbon thickness. Our approach opens a new route to develop carbon-based inexpensive electronic and optoelectronic devices.

  12. Atomic Resolution Imaging of Nanoscale Structural Ordering in a Complex Metal Oxide Catalyst

    KAUST Repository

    Zhu, Yihan

    2012-08-28

    The determination of the atomic structure of a functional material is crucial to understanding its "structure-to-property" relationship (e.g., the active sites in a catalyst), which is however challenging if the structure possesses complex inhomogeneities. Here, we report an atomic structure study of an important MoVTeO complex metal oxide catalyst that is potentially useful for the industrially relevant propane-based BP/SOHIO process. We combined aberration-corrected scanning transmission electron microscopy with synchrotron powder X-ray crystallography to explore the structure at both nanoscopic and macroscopic scales. At the nanoscopic scale, this material exhibits structural and compositional order within nanosized "domains", while the domains show disordered distribution at the macroscopic scale. We proposed that the intradomain compositional ordering and the interdomain electric dipolar interaction synergistically induce the displacement of Te atoms in the Mo-V-O channels, which determines the geometry of the multifunctional metal oxo-active sites.

  13. Self-Templated Stepwise Synthesis of Monodispersed Nanoscale Metalated Covalent Organic Polymers for In Vivo Bioimaging and Photothermal Therapy.

    Science.gov (United States)

    Shi, Yanshu; Deng, Xiaoran; Bao, Shouxin; Liu, Bei; Liu, Bin; Ma, Ping'an; Cheng, Ziyong; Pang, Maolin; Lin, Jun

    2017-07-10

    Size- and shape-controlled growth of nanoscale microporous organic polymers (MOPs) is a big challenge scientists are confronted with; meanwhile, rendering these materials for in vivo biomedical applications is still scarce. In this study, a monodispersed nanometalated covalent organic polymer (MCOP, M=Fe, Gd) with sizes around 120 nm was prepared by a self-templated two-step solution-phase synthesis method. The metal ions (Fe(3+) , Gd(3+) ) played important roles in generating a small particle size and in the functionalization of the products during the reaction with p-phenylenediamine (Pa). The resultant Fe-Pa complex was used as a template for the subsequent formation of MCOP following the Schiff base reaction with 1,3,5-triformylphloroglucinol (Tp). A high tumor suppression efficiency for this Pa-based COP is reported for the first time. This study demonstrates the potential use of MCOP as a photothermal agent for photothermal therapy (PTT) and also provides an alternative route to fabricate nano-sized MCOPs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro.

    Science.gov (United States)

    Ren, Fei; Yang, Baochun; Cai, Jing; Jiang, Yaodong; Xu, Jun; Wang, Shan

    2014-04-30

    Metal-organic frameworks (MOFs) possess unique properties desirable for delivery of drugs and gaseous therapeutics, but their uncharacterized interactions with cells raise increasing concerns of their safety in such biomedical applications. We evaluated the adverse effects of zinc nanoscale MOFs on the cell morphology, cytoskeleton, cell viability and expression of neurotrophin signaling pathway-associated GAP-43 protein in rat pheochromocytoma PC12 cells. At the concentration of 25 μg/ml, zinc MOFs did not significantly affect morphology, viability and membrane integrity of the cells. But at higher concentrations (over 100 μg/ml), MOFs exhibited a time- and concentration-dependent cytotoxicity, indicating their entry into the cells via endocytosis where they release Zn(2+) into the cytosol to cause increased intracellular concentration of Zn(2+). We demonstrated that the toxicity of MOFs was associated with a disrupted cellular zinc homeostasis and down-regulation of GAP-43 protein, which might be the underlying mechanism for the improved differentiation in PC12 cells. These findings highlight the importance of cytotoxic evaluation of the MOFs before their biomedical application.

  15. A spray-drying strategy for synthesis of nanoscale metal-organic frameworks and their assembly into hollow superstructures.

    Science.gov (United States)

    Carné-Sánchez, Arnau; Imaz, Inhar; Cano-Sarabia, Mary; Maspoch, Daniel

    2013-03-01

    Metal-organic frameworks (MOFs) are among the most attractive porous materials known today. Their miniaturization to the nanoscale--into nanoMOFs--is expected to serve myriad applications from drug delivery to membranes, to open up novel avenues to more traditional storage and catalysis applications, and to enable the creation of sophisticated superstructures. Here, we report the use of spray-drying as a versatile methodology to assemble nanoMOFs, yielding spherical hollow superstructures with diameters smaller than 5 µm. This strategy conceptually mimics the emulsions used by chemists to confine the synthesis of materials, but does not require secondary immiscible solvents or surfactants. We demonstrate that the resulting spherical, hollow superstructures can be processed into stable colloids, whose disassembly by sonication affords discrete, homogeneous nanoMOFs. This spray-drying strategy enables the construction of multicomponent MOF superstructures, and the encapsulation of guest species within these superstructures. We anticipate that this will provide new routes to capsules, reactors and composite materials.

  16. Oxidation does not (always) kill reactivity of transition metals: solution-phase conversion of nanoscale transition metal oxides to phosphides and sulfides.

    Science.gov (United States)

    Muthuswamy, Elayaraja; Brock, Stephanie L

    2010-11-17

    Unexpected reactivity on the part of oxide nanoparticles that enables their transformation into phosphides or sulfides by solution-phase reaction with trioctylphosphine (TOP) or sulfur, respectively, at temperatures of ≤370 °C is reported. Impressively, single-phase phosphide products are produced, in some cases with controlled anisotropy and narrow polydispersity. The generality of the approach is demonstrated for Ni, Fe, and Co, and while manganese oxides are not sufficiently reactive toward TOP to form phosphides, they do yield MnS upon reaction with sulfur. The reactivity can be attributed to the small size of the precursor particles, since attempts to convert bulk oxides or even particles with sizes approaching 50 nm were unsuccessful. Overall, the use of oxide nanoparticles, which are easily accessed via reaction of inexpensive salts with air, in lieu of organometallic reagents (e.g., metal carbonyls), which may or may not be transformed into metal nanoparticles, greatly simplifies the production of nanoscale phosphides and sulfides. The precursor nanoparticles can easily be produced in large quantities and stored in the solid state without concern that "oxidation" will limit their reactivity.

  17. Encapsulation of nanoscale metal oxides into an ultra-thin Ni matrix for superior Li-ion batteries: a versatile strategy.

    Science.gov (United States)

    Zhu, Jianhui; Jiang, Jian; Ai, Wei; Fan, Zhanxi; Huang, Xintang; Zhang, Hua; Yu, Ting

    2014-11-01

    Li-ion batteries' (LIBs) performance proves to be highly correlated with ionic and electrical transport kinetics in electrodes. Although continual progress has been achieved in rational design of ideal electrode systems, their energy density, cyclic endurance and productivity are still far from perfect for practical use. Herein we propose an interesting, facile and versatile strategy to encapsulate various nanoscale metal oxides (covering both nanopowders and nanostructured arrays) into an ultrathin Ni matrix (metal oxide@Ni) for superior LIBs. Evolutions of such metal oxide@Ni hybrids (taking MnO@Ni and CoO@Ni as models) are thoroughly studied by monitoring their whole fabrication process. Putting "armors" on nanoscale metal oxides is thought helpful for the promotion of the LIB performance since the outer Ni matrix provides both mechanical protection against huge volume changes and effective routes for electron transfer. As a proof-of-concept demonstration, all metal oxide@Ni hybrid electrodes exhibit drastic improvements in the capacity retention (e.g. ∼452% capacity rise for the MnO@Ni case while ∼551% for CoO@Ni NWs), long-term cyclic stability and rate capabilities. This designed strategy can be further extended to make other advanced oxide@metal hybrids, not only for LIBs but also for other potential fields.

  18. Humic acid and metal ions accelerating the dechlorination of 4-chlorobiphenyl by nanoscale zero-valent iron

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Dongmei Zhou; Yujun Wang; Xiangdong Zhu; Shengyang Jin

    2011-01-01

    Transformation of polychlorinated biphenyls (PCBs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation.The dechlorination of 4-chlorobiphenyl (4-C1BP) by nanoscale zero-valent iron (NZVI) in the presence of humic acid or metal ions was investigated.The results showed that the de chlorination of 4-CIBP by NZVI increased with decreased solution pH.When the initial pH value was 4.0,5.5,6.8,and 9.0,the de chlorination efliciencies of 4-C1BP after 48 hr were 53.8%,47.8%,35.7%,and 35.6%,respectively.The presence of humic acid inhibited the reduction of 4-ClBP in the first 4 hr,and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr.Divalent metal ions,Co2+,Cu2+,and Ni2+,were reduced and formed bimetals with NZVI,thereby enhanced the dechlorination of 4-CIBP.The dechlorination percentages of 4-CIBP in the presence of 0.1 mmol/L Co2+,Cu2+ and Ni2+ were 66.1%,66.0% and 64.6% in 48 hr,and then increased to 67.9%,71.3% and 73.5%,after 96 hr respectively.The dechlorination kinetics of 4-CIBP by the NZVI in all cases followed pseudo-first order model.The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.

  19. Internal Morphologies of Cycled Li-Metal Electrodes Investigated by Nano-Scale Resolution X-ray Computed Tomography.

    Science.gov (United States)

    Frisco, Sarah; Liu, Danny X; Kumar, Arjun; Whitacre, Jay F; Love, Corey T; Swider-Lyons, Karen E; Litster, Shawn

    2017-06-07

    While some commercially available primary batteries have lithium metal anodes, there has yet to be a commercially viable secondary battery with this type of electrode. Research prototypes of these cells typically exhibit a limited cycle life before dendrites form and cause internal cell shorting, an occurrence that is more pronounced during high-rate cycling. To better understand the effects of high-rate cycling that can lead to cell failure, we use ex situ nanoscale-resolution X-ray computed tomography (nano-CT) with the aid of Zernike phase contrast to image the internal morphologies of lithium metal electrodes on copper wire current collectors that have been cycled at low and high current densities. The Li that is deposited on a Cu wire and then stripped and deposited at low current density appears uniform in morphology. Those cycled at high current density undergo short voltage transients to >3 V during Li-stripping from the electrode, during which electrolyte oxidation and Cu dissolution from the current collector may occur. The effect of temperature is also explored with separate cycling experiments performed at 5 and 33 °C. The resulting morphologies are nonuniform films filled with voids that are semispherical in shape with diameters ranging from hundreds of nanometers to tens of micrometers, where the void size distributions are temperature-dependent. Low-temperature cycling elicits a high proportion of submicrometer voids, while the higher-temperature sample morphology is dominated by voids larger than 2 μm. In evaluating these morphologies, we consider the importance of nonidealities during extreme charging, such as electrolyte decomposition. We conclude that nano-CT is an effective tool for resolving features and aggressive cycling-induced anomalies in Li films in the range of 100 nm to 100 μm.

  20. Spintronic materials and devices based on antiferromagnetic metals

    Directory of Open Access Journals (Sweden)

    Y.Y. Wang

    2017-04-01

    Full Text Available In this paper, we review our recent experimental developments on antiferromagnet (AFM spintronics mainly comprising Mn-based noncollinear AFM metals. IrMn-based tunnel junctions and Hall devices have been investigated to explore the manipulation of AFM moments by magnetic fields, ferromagnetic materials and electric fields. Room-temperature tunneling anisotropic magnetoresistance based on IrMn as well as FeMn has been successfully achieved, and electrical control of the AFM exchange spring is realized by adopting ionic liquid. In addition, promising spin-orbit effects in AFM as well as spin transfer via AFM spin waves reported by different groups have also been reviewed, indicating that the AFM can serve as an efficient spin current source. To explore the crucial role of AFM acting as efficient generators, transmitters, and detectors of spin currents is an emerging topic in the field of magnetism today. AFM metals are now ready to join the rapidly developing fields of basic and applied spintronics, enriching this area of solid-state physics and microelectronics.

  1. Nanoscale optical properties of metal nanoparticles probed by Second Harmonic Generation microscopy.

    Science.gov (United States)

    Shen, Hong; Nguyen, Ngoc; Gachet, David; Maillard, Vincent; Toury, Timothée; Brasselet, Sophie

    2013-05-20

    We report spatial and vectorial imaging of local fields' confinement properties in metal nanoparticles with branched shapes, using Second Harmonic Generation (SHG) microscopy. Taking advantage of the coherent nature of this nonlinear process, the technique provides a direct evidence of the coupling between the excitation polarization and both localization and polarization specificities of local fields at the sub-diffraction scale. These combined features, which are governed by the nanoparticles' symmetry, are not accessible using other contrasts such as linear optical techniques or two-photon luminescence.

  2. Attosecond physics at a nanoscale metal tip: strong field physics meets near-field optics

    Science.gov (United States)

    Krüger, M.; Thomas, S.; Förster, M.; Maisenbacher, L.; Wachter, G.; Lemell, Chr.; Burgdörfer, J.; Hommelhoff, P.

    2013-03-01

    Attosecond physics, centering on the control of electronic matter waves within a single cycle of the optical laser's driving field, has led to tremendously successful experiments with atoms and molecules in the gas phase. We show that pivotal phenomena such as elastic electron rescattering at the parent matter, a strong carrier-evenlope phase sensitivity and electronic matter wave intereference also show up in few-cycle laser driven electron emission from nanometric sharp metal tips. Furthermore, we utilize spectral signatures to measure the enhanced near-field with a spatial resolution of 1nm.

  3. MATHEMATICAL MODELING OF NANO-SCALE PROCESSES OF INJECTION-BASED PROTECTION OF METALS

    Directory of Open Access Journals (Sweden)

    Pavlyuchko Anatoliy Ivanovich

    2012-12-01

    Full Text Available The authors have employed methods of molecular dynamics to complete their analysis of the physical phenomena that occur in the process of spattering of nanoparticles over the metal surface. The contact between moving nanoparticles and the surface contemplates several simultaneous physical processes: transformation of the kinetic energy of motion into the thermal energy, partial or complete melting and partial melting of nanoparticles in contact with the surface, rapid cooling of nanoparticles and the surface, and crystallization of the melted portion of nanoparticles and the surface. The intensity of these physical processes is substantially dependent on the sizes of nanoparticles, their initial temperature and velocity. Therefore, the final state of the metal surface strongly depends on the process parameters. Numerical methods of molecular dynamics were employed to identify the quantitative and qualitative characteristics of the process depending on the size, shape, chemical nature, velocity and temperature of nanoparticles. The authors have demonstrated that by changing the technological parameters of solenoid injection nanoparticles (by changing the composition of nanoparticles, their size, shape, temperature and initial velocity, nano-crystalline and amorphous states of the surface may be changed, and the surface strength may be improved.

  4. Inverse polarity of the resistive switching effect and strong inhomogeneity in nanoscale YBCO-metal contacts

    Science.gov (United States)

    Truchly, M.; Plecenik, T.; Zhitlukhina, E.; Belogolovskii, M.; Dvoranova, M.; Kus, P.; Plecenik, A.

    2016-11-01

    We have studied a bipolar resistive switching phenomenon in c-axis oriented normal-state YBa2Cu3O7-c (YBCO) thin films at room temperature by scanning spreading resistance microscopy (SSRM) and scanning tunneling microscopy (STM) techniques. The most striking experimental finding has been the opposite (in contrast to the previous room and low-temperature data for planar metal counter-electrode-YBCO bilayers) voltage-bias polarity of the switching effect in all SSRM and a number of STM measurements. We have assumed that the hysteretic phenomena in current-voltage characteristics of YBCO-based contacts can be explained by migration of oxygen-vacancy defects and, as a result, by the formation or dissolution of more or less conductive regions near the metal-YBCO interface. To support our interpretation of the macroscopic resistive switching phenomenon, a minimalist model that describes radical modifications of the oxygen-vacancy effective charge in terms of a charge-wind effect was proposed. It was shown theoretically that due to the momentum exchange between current carriers (holes in the YBCO compound) and activated oxygen ions, the direction in which oxygen vacancies are moving is defined by the balance between the direct electrostatic force on them and that caused by the current-carrier flow.

  5. Balancing innovation and medical device regulation: the case of modern metal-on-metal hip replacements

    Directory of Open Access Journals (Sweden)

    Howard JJ

    2016-08-01

    Full Text Available Jason J Howard1,2 1Division of Orthopedic Surgery, Department of Surgery, Sidra Medical and Research Center, 2Department of Orthopedic Surgery, Weill Cornell Medical College, Doha, Qatar Abstract: Due to problems with wear particle generation and subsequent loosening using conventional metal-on-polyethylene total hip replacements, there has been a shift toward alternative bearing systems, including metal-on-metal (MoM, for younger, more active patients with degenerative joint disease. Based on positive results from early short-term clinical studies, MoM hip replacements were readily adopted by orthopedic surgeons with thousands being implanted worldwide over the past decade. Unacceptably high revision rates reported by two national joint registries called into question the rigorousness of the regulatory approval process for these implants, particularly with respect to premarket data requirements to prove safety, effectiveness, and the appropriateness of the regulatory pathway chosen. The purpose of this review was to investigate the balance between facilitating the introduction of new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment. The case of MoM hip replacement devices was used to frame the investigation and subsequent discussions. The regulatory approval processes and post-market surveillance requirements associated with three common MoM hip replacements (two resurfacings: the Birmingham and articular surface replacement and the articular surface replacement XL total hip replacement were investigated. With respect to modern MoM hip replacement devices, the balance between facilitating the introduction of these new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment was not achieved. The lessons learned from these experiences have application beyond joint replacements to the introduction of new medical technologies in

  6. Decoration of Micro-/Nanoscale Noble Metal Particles on 3D Porous Nickel Using Electrodeposition Technique as Electrocatalyst for Hydrogen Evolution Reaction in Alkaline Electrolyte.

    Science.gov (United States)

    Qian, Xin; Hang, Tao; Shanmugam, Sangaraju; Li, Ming

    2015-07-29

    Micro-/nanoscale noble metal (Ag, Au, and Pt) particle-decorated 3D porous nickel electrodes for hydrogen evolution reaction (HER) in alkaline electrolyte are fabricated via galvanostatic electrodeposition technique. The developed electrodes are characterized by field emission scanning electron microscopy and electrochemical measurements including Tafel polarization curves, cyclic voltammetry, and electrochemical impedance spectroscopy. It is clearly shown that the enlarged real surface area caused by 3D highly porous dendritic structure has greatly reinforced the electrocatalytic activity toward HER. Comparative analysis of electrodeposited Ag, Au, and Pt particle-decorated porous nickel electrodes for HER indicates that both intrinsic property and size of the noble metal particles can lead to distinct catalytic activities. Both nanoscale Au and Pt particles have further reinforcement effect toward HER, whereas microscale Ag particles exhibit the reverse effect. As an effective 3D hydrogen evolution cathode, the nanoscale Pt-particle-decorated 3D porous nickel electrode demonstrates the highest catalytic activity with an extremely low overpotential of -0.045 V for hydrogen production, a considerable exchange current density of 9.47 mA cm(-2) at 25 °C, and high durability in long-term electrolysis, all of which are attributed to the intrinsic catalytic property and the extremely small size of Pt particles.

  7. Balancing innovation and medical device regulation: the case of modern metal-on-metal hip replacements

    Science.gov (United States)

    Howard, Jason J

    2016-01-01

    Due to problems with wear particle generation and subsequent loosening using conventional metal-on-polyethylene total hip replacements, there has been a shift toward alternative bearing systems, including metal-on-metal (MoM), for younger, more active patients with degenerative joint disease. Based on positive results from early short-term clinical studies, MoM hip replacements were readily adopted by orthopedic surgeons with thousands being implanted worldwide over the past decade. Unacceptably high revision rates reported by two national joint registries called into question the rigorousness of the regulatory approval process for these implants, particularly with respect to premarket data requirements to prove safety, effectiveness, and the appropriateness of the regulatory pathway chosen. The purpose of this review was to investigate the balance between facilitating the introduction of new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment. The case of MoM hip replacement devices was used to frame the investigation and subsequent discussions. The regulatory approval processes and post-market surveillance requirements associated with three common MoM hip replacements (two resurfacings: the Birmingham and articular surface replacement and the articular surface replacement XL total hip replacement) were investigated. With respect to modern MoM hip replacement devices, the balance between facilitating the introduction of these new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment was not achieved. The lessons learned from these experiences have application beyond joint replacements to the introduction of new medical technologies in general, particularly for those who have a significant potential for harm. In this regard, a series of recommendations have been developed to contribute to the evolution of the medical device regulatory process

  8. Nanoscale-phase-separated Pd-Rh boxes synthesized via metal migration: an archetype for studying lattice strain and composition effects in electrocatalysis.

    Science.gov (United States)

    Sneed, Brian T; Brodsky, Casey N; Kuo, Chun-Hong; Lamontagne, Leo K; Jiang, Ying; Wang, Yong; Tao, Franklin Feng; Huang, Weixin; Tsung, Chia-Kuang

    2013-10-02

    Developing syntheses of more sophisticated nanostructures comprising late transition metals broadens the tools to rationally design suitable heterogeneous catalysts for chemical transformations. Herein, we report a synthesis of Pd-Rh nanoboxes by controlling the migration of metals in a core-shell nanoparticle. The Pd-Rh nanobox structure is a grid-like arrangement of two distinct metal phases, and the surfaces of these boxes are {100} dominant Pd and Rh. The catalytic behaviors of the particles were examined in electrochemistry to investigate strain effects arising from this structure. It was found that the trends in activity of model fuel cell reactions cannot be explained solely by the surface composition. The lattice strain emerging from the nanoscale separation of metal phases at the surface also plays an important role.

  9. NANOSCALE STRUCTURES GENERATION WITHIN THE SURFACE LAYER OF METALS WITH SHORT UV LASER PULSES

    Directory of Open Access Journals (Sweden)

    Dmitry S. Ivanov

    2017-01-01

    Full Text Available We have completed modeling of a laser pulse influence on a gold target. We have applied a hybrid atomistic-continuum model to analyze the physical mechanisms responsible for the process of nanostructuring. The model combines the advantages of Molecular Dynamics and Two Temperature Model. We have carried out a direct comparison of the modeling results and experimental data on nano-modification due to a single ps laser pulse at the energy densities significantly exceeding the melting threshold. The experimental data is obtained due to a laser pulse irradiation at the wavelength of 248 nm and duration of 1.6 ps. The mask projection (diffraction grating creates the sinusoidal intensity distribution on a gold surface with periods of 270 nm, 350 nm, and 500 nm. The experimental data and modeling results have demonstrated a good match subject to complex interrelations between a fast material response to the laser excitation, generation of crystal defects, phase transitions and hydrodynamic motion of matter under condition of strong laser-induced non-equilibrium. The performed work confirms the proposed approach as a powerful tool for revealing the physical mechanisms underlying the process of nanostructuring of metal surfaces. Detailed understanding of the dynamics of these processes gives the possibility for designing the topology of functional surfaces on nano- and micro-scales.

  10. Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

    Science.gov (United States)

    He, Jie; Kaban, Ivan; Mattern, Norbert; Song, Kaikai; Sun, Baoan; Zhao, Jiuzhou; Kim, Do Hyang; Eckert, Jürgen; Greer, A. Lindsay

    2016-01-01

    At room temperature, plastic flow of metallic glasses (MGs) is sharply localized in shear bands, which are a key feature of the plastic deformation in MGs. Despite their clear importance and decades of study, the conditions for formation of shear bands, their structural evolution and multiplication mechanism are still under debate. In this work, we investigate the local conditions at shear bands in new phase-separated bulk MGs containing glassy nanospheres and exhibiting exceptional plasticity under compression. It is found that the glassy nanospheres within the shear band dissolve through mechanical mixing driven by the sharp strain localization there, while those nearby in the matrix coarsen by Ostwald ripening due to the increased atomic mobility. The experimental evidence demonstrates that there exists an affected zone around the shear band. This zone may arise from low-strain plastic deformation in the matrix between the bands. These results suggest that measured property changes originate not only from the shear bands themselves, but also from the affected zones in the adjacent matrix. This work sheds light on direct visualization of deformation-related effects, in particular increased atomic mobility, in the region around shear bands. PMID:27181922

  11. Second harmonic generation in nanoscale films of transition metal dichalcogenide: Accounting for multipath interference

    Directory of Open Access Journals (Sweden)

    A. V. Kudryavtsev

    2016-09-01

    Full Text Available The transfer matrix method has been widely used to calculate wave propagation through the layered structures consisting entirely of either linear or nonlinear optical materials. In the present work, we develop the transfer matrix method for structures consisting of alternating layers of linear and nonlinear optical materials. The result is presented in a form that allows one to directly substitute the values of material constants, refractive index and absorption coefficient, into the expressions describing the second harmonic generation (SHG field. The model is applied to the calculation of second harmonic (SH field generated in nano-thin layers of transition metal dichalcogenides exfoliated on top of silicon oxide/silicon Fabry-Perot cavity. These structures are intensively studied both in view of their unique properties and perspective applications. A good agreement between experimental and numerical results can be achieved by small modification of optical constants, which may arise in an experiment due to a strong electric field of an incident focused pump laser beam. By considering the SHG effect, this paper completes the series of works describing the role of Fabry-Perot cavity in different optical effects (optical reflection, photoluminescence and Raman scattering in 2D semiconductors that is extremely important for characterization of these unique materials.

  12. Porous metal-organic-framework nanoscale carriers as a potential platform for drug delivery and imaging

    Science.gov (United States)

    Horcajada, Patricia; Chalati, Tamim; Serre, Christian; Gillet, Brigitte; Sebrie, Catherine; Baati, Tarek; Eubank, Jarrod F.; Heurtaux, Daniela; Clayette, Pascal; Kreuz, Christine; Chang, Jong-San; Hwang, Young Kyu; Marsaud, Veronique; Bories, Phuong-Nhi; Cynober, Luc; Gil, Sophie; Férey, Gérard; Couvreur, Patrick; Gref, Ruxandra

    2010-02-01

    In the domain of health, one important challenge is the efficient delivery of drugs in the body using non-toxic nanocarriers. Most of the existing carrier materials show poor drug loading (usually less than 5wt% of the transported drug versus the carrier material) and/or rapid release of the proportion of the drug that is simply adsorbed (or anchored) at the external surface of the nanocarrier. In this context, porous hybrid solids, with the ability to tune their structures and porosities for better drug interactions and high loadings, are well suited to serve as nanocarriers for delivery and imaging applications. Here we show that specific non-toxic porous iron(III)-based metal-organic frameworks with engineered cores and surfaces, as well as imaging properties, function as superior nanocarriers for efficient controlled delivery of challenging antitumoural and retroviral drugs (that is, busulfan, azidothymidine triphosphate, doxorubicin or cidofovir) against cancer and AIDS. In addition to their high loadings, they also potentially associate therapeutics and diagnostics, thus opening the way for theranostics, or personalized patient treatments.

  13. Second harmonic generation in nanoscale films of transition metal dichalcogenide: Accounting for multipath interference

    Science.gov (United States)

    Kudryavtsev, A. V.; Lavrov, S. D.; Shestakova, A. P.; Kulyuk, L. L.; Mishina, E. D.

    2016-09-01

    The transfer matrix method has been widely used to calculate wave propagation through the layered structures consisting entirely of either linear or nonlinear optical materials. In the present work, we develop the transfer matrix method for structures consisting of alternating layers of linear and nonlinear optical materials. The result is presented in a form that allows one to directly substitute the values of material constants, refractive index and absorption coefficient, into the expressions describing the second harmonic generation (SHG) field. The model is applied to the calculation of second harmonic (SH) field generated in nano-thin layers of transition metal dichalcogenides exfoliated on top of silicon oxide/silicon Fabry-Perot cavity. These structures are intensively studied both in view of their unique properties and perspective applications. A good agreement between experimental and numerical results can be achieved by small modification of optical constants, which may arise in an experiment due to a strong electric field of an incident focused pump laser beam. By considering the SHG effect, this paper completes the series of works describing the role of Fabry-Perot cavity in different optical effects (optical reflection, photoluminescence and Raman scattering) in 2D semiconductors that is extremely important for characterization of these unique materials.

  14. Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation.

    Science.gov (United States)

    He, Jie; Kaban, Ivan; Mattern, Norbert; Song, Kaikai; Sun, Baoan; Zhao, Jiuzhou; Kim, Do Hyang; Eckert, Jürgen; Greer, A Lindsay

    2016-05-16

    At room temperature, plastic flow of metallic glasses (MGs) is sharply localized in shear bands, which are a key feature of the plastic deformation in MGs. Despite their clear importance and decades of study, the conditions for formation of shear bands, their structural evolution and multiplication mechanism are still under debate. In this work, we investigate the local conditions at shear bands in new phase-separated bulk MGs containing glassy nanospheres and exhibiting exceptional plasticity under compression. It is found that the glassy nanospheres within the shear band dissolve through mechanical mixing driven by the sharp strain localization there, while those nearby in the matrix coarsen by Ostwald ripening due to the increased atomic mobility. The experimental evidence demonstrates that there exists an affected zone around the shear band. This zone may arise from low-strain plastic deformation in the matrix between the bands. These results suggest that measured property changes originate not only from the shear bands themselves, but also from the affected zones in the adjacent matrix. This work sheds light on direct visualization of deformation-related effects, in particular increased atomic mobility, in the region around shear bands.

  15. Atomic origin of ultrafast resistance switching in nanoscale electrometallization cells.

    Science.gov (United States)

    Onofrio, Nicolas; Guzman, David; Strachan, Alejandro

    2015-04-01

    Nanoscale resistance-switching cells that operate via the electrochemical formation and disruption of metallic filaments that bridge two electrodes are among the most promising devices for post-CMOS electronics. Despite their importance, the mechanisms that govern their remarkable properties are not fully understood, especially for nanoscale devices operating at ultrafast rates, limiting our ability to assess the ultimate performance and scalability of this technology. We present the first atomistic simulations of the operation of conductive bridging cells using reactive molecular dynamics with a charge equilibration method extended to describe electrochemical reactions. The simulations predict the ultrafast switching observed in these devices, with timescales ranging from hundreds of picoseconds to a few nanoseconds for devices consisting of Cu active electrodes and amorphous silica dielectrics and with dimensions corresponding to their scaling limit (cross-sections below 10 nm). We find that single-atom-chain bridges often form during device operation but that they are metastable, with lifetimes below a nanosecond. The formation of stable filaments involves the aggregation of ions into small metallic clusters, followed by a progressive chemical reduction as they become connected to the cathode. Contrary to observations in larger cells, the nanoscale conductive bridges often lack crystalline order. An atomic-level mechanistic understanding of the switching process provides guidelines for materials optimization for such applications and the quantitative predictions over an ensemble of devices provide insight into their ultimate scaling and performance.

  16. Metal-dielectric hybrid surfaces as integrated optoelectronic interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Narasimhan, Vijay K.; Hymel, Thomas M.; Lai, Ruby A.; Cui, Yi

    2017-01-03

    An optoelectronic device has a hybrid metal-dielectric optoelectronic interface including an array of nanoscale dielectric resonant elements (e.g., nanopillars), and a metal film disposed between the dielectric resonant elements and below a top surface of the resonant elements such that the dielectric resonant elements protrude through the metal film. The device may also include an anti-reflection coating. The device may further include a metal film layer on each of the dielectric resonant elements.

  17. Electrostatic effects of Au nanoparticles on near-infrared photoluminescence from Si/SiGe due to nanoscale metal/semiconductor contact.

    Science.gov (United States)

    Yin, Yefei; Wang, Ze; Wang, Shuguang; Bai, Yujie; Jiang, Zuimin; Zhong, Zhenyang

    2017-02-21

    The photoluminescence from the Si and the SiGe is comprehensively modified by the Au NPs under the excitation without the surface plasmon resonance. Moreover, it sensitively depends on the size of the Au NPs, the excitation power and the thickness of Si between the Au NPs and the SiGe. A model is proposed in terms of the electrostatic effects of the naturally charged Au NPs due to the electron transferring through the nanoscale metal/semiconductor Schottky junction without an external bias and an external injection of carriers. It well accounts for all those unique PL features. It also reveals that Au NPs can substantially modify the energy band structures, the distribution and the transition of carriers in the nanoscale region below the Au NPs. Our results demonstrate that the Au NPs on semiconductor can efficiently modulate the light-matter interaction from the fundamental aspect of the matter as well as the light.

  18. Nanoscale Chemical and Valence Evolution at the Metal/Oxide Interface: A Case Study of Ti/SrTiO 3

    KAUST Repository

    Li, Yangyang

    2016-06-27

    Metal/oxide interfaces are ubiquitous in a wide range of applications such as electronics, photovoltaics, memories, catalysis, and sensors. However, there have been few investigations dedicated to the nanoscale structural and chemical characteristics of these buried interfaces. In this work, the metal/oxide interface between Ti and SrTiO3 (STO) is examined as a prototypical system using high-resolution scanning transmission electron microscopy and electron energy loss spectroscopy. An atomic-thin Ti2O3-like layer at the Ti/STO interface prepared at room temperature is discovered, and first-principles calculations predict a metallic band structure of this 2D electron system. As a universal feature of such interfaces prepared at different temperatures, near the interface nanoscale oxygen-deficient domains and continuous modulation of Ti oxidation states are found. Overall, these results directly reveal complex chemical and valence evolutions at the metal/oxide interfaces, providing microscopic insights on such heterostructures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  19. Physical Removal of Metallic Carbon Nanotubes from Nanotube Network Devices Using a Thermal and Fluidic Process

    OpenAIRE

    Ford, Alexandra C.; Shaughnessy, Michael; Wong, Bryan M.; Kane, Alexander A.; Kuznetsov, Oleksandr V.; Krafcik, Karen L.; Billups, W. E.; Hauge, Robert H.; Léonard, François

    2013-01-01

    Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is ...

  20. Complex Phenomena in Nanoscale Systems

    CERN Document Server

    Casati, Giulio

    2009-01-01

    Nanoscale physics has become one of the rapidly developing areas of contemporary physics because of its direct relevance to newly emerging area, nanotechnologies. Nanoscale devices and quantum functional materials are usually constructed based on the results of fundamental studies on nanoscale physics. Therefore studying physical phenomena in nanosized systems is of importance for progressive development of nanotechnologies. In this context study of complex phenomena in such systems and using them for controlling purposes is of great practical importance. Namely, such studies are brought together in this book, which contains 27 papers on various aspects of nanoscale physics and nonlinear dynamics.

  1. Metal-Organic Frameworks as Active Materials in Electronic Sensor Devices.

    Science.gov (United States)

    Campbell, Michael G; Dincă, Mircea

    2017-05-12

    In the past decade, advances in electrically conductive metal-organic frameworks (MOFs) and MOF-based electronic devices have created new opportunities for the development of next-generation sensors. Here we review this rapidly-growing field, with a focus on the different types of device configurations that have allowed for the use of MOFs as active components of electronic sensor devices.

  2. Dielectric-function analysis of metals for plasmonic-device application

    Science.gov (United States)

    Dimas Satrya, Christoforus; Darma, Yudi

    2017-07-01

    We study the potential of various metals (Pt, Al, Cu and Ni) as plasmonic material used for devices by analyzing their complex permittivity and comparing with other metals. Metals were characterized by using high-resolution spectroscopic ellipsometry covering energy range of 0.5 to 6.5 eV. In fitting process, instead using Drude model, we used the combination of Lorentz model to describe optical properties of metals. The results show that each metal has unique different features of ε1 and ε2 in range of far-infrared to vacuum-ultraviolet. Also, the loss by interband transition is observable for some metals. Furthermore, the plasmonic quality-factor, which are related to electric-field enhancement and heat production generated by surface plasmon, of metal nanoparticle have been calculated and we found the optimum region of device application for each metal. From this study, Cu is promising metal working in near-infrared to visible area potentially to substitute noble Ag and Au. On the other hand, Al is the best metal to be applied as plasmonic device working in ultraviolet region. Moreover, enhancement of plasmonic quality-factor by changing geometry and environment of metal is also discussed. Our studies give an alternative of fundamental perspective for plasmonic-device development especially for energy-harvesting purposes.

  3. Nanoscale Organic Hybrid Electrolytes

    KAUST Repository

    Nugent, Jennifer L.

    2010-08-20

    Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Improved Understanding of Space Radiation Effects on Exploration Electronics by Advanced Modeling of Nanoscale Devices and Novel Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA space exploration missions will use nanometer-scale electronic technologies which call for a shift in how radiation effects in such devices and materials...

  5. Cation exchange on the nanoscale: an emerging technique for new material synthesis, device fabrication, and chemical sensing.

    Science.gov (United States)

    Rivest, Jessy B; Jain, Prashant K

    2013-01-01

    Cation exchange is an age-old technique for the chemical conversion of liquids or extended solids by place-exchanging the cations in an ionic material with a different set of cations. The technique is undergoing a major revival with the advent of high-quality nanocrystals: researchers are now able to overcome the limitations in bulk systems and fully exploit cation exchange for materials synthesis and discovery via rapid, low-temperature transformations in the solid state. In this tutorial review, we discuss cation exchange as a promising materials synthesis and discovery tool. Exchange on the nanoscale exhibits some unique attributes: rapid kinetics at room temperature (orders of magnitude faster than in the bulk) and the tuning of reactivity via control of nanocrystal size, shape, and surface faceting. These features make cation exchange a convenient tool for accessing nanocrystal compositions and morphologies for which conventional synthesis may not be established. A simple exchange reaction allows extension of nanochemistry to a larger part of the periodic table, beyond the typical gamut of II-VI, IV-VI, and III-V materials. Cation exchange transformations in nanocrystals can be topotactic and size- and shape-conserving, allowing nanocrystals synthesized by conventional methods to be used as templates for production of compositionally novel, multicomponent, or doped nanocrystals. Since phases and compositions resulting from an exchange reaction can be kinetically controlled, rather than governed by the phase diagram, nanocrystals of metastable and hitherto inaccessible compositions are attainable. Outside of materials synthesis, applications for cation exchange exist in water purification, chemical staining, and sensing. Since nanoscale cation exchange occurs rapidly at room temperature, it can be integrated with sensitive environments such as those in biological systems. Cation exchange is already allowing access to a variety of new materials and processes

  6. High yield, single droplet electrode arrays for nanoscale printed electronics.

    Science.gov (United States)

    Caironi, Mario; Gili, Enrico; Sakanoue, Tomo; Cheng, Xiaoyang; Sirringhaus, Henning

    2010-03-23

    In this work we demonstrate two building blocks of a scalable manufacturing technology for nanoscale electronic devices based on direct-write printing: an architecture for high-yield printing of electrode gaps with 100 nm dimension and a low-temperature silver complex ink for integration of organic materials with high conductivity metal interconnects. We use single printed droplets that are made to dewet slowly from each other to allow reliable, high yield patterning even in the presence of certain surface defects.

  7. Asymmetric propagation of electromagnetic waves through nanoscale spirals

    Science.gov (United States)

    Hu, Jingpei; Lin, Yu; Zhu, Aijiao; Zhao, Xiaonan; Wang, Chinhua

    2016-10-01

    In this paper, we report that normal incidence transmission of different circularly polarized waves through the 2D Archimedes' nanoscale spirals is asymmetric. The structures consist of raised spiral ridge and two layers metal film covered on the substrate and the ridge. The finite difference time domain method was used to design the structure and perform the simulation. The device can distinguish the different circularly polarized wave across the transmission intensity compare with the common Archimedes' nanoscale spirals which just exhibit the bright or dark modes in the light field. We confirmed that the device provide about 10% circular dichroism in 3.85um-6.0um broadband region. The circular dichroism in the wavelength 3.95 um can reach 13%. This ultracompact device could prove useful for remote sensing and advanced telecommunication applications.

  8. Investigation of over-moulded hybrid metal/polymer devices

    DEFF Research Database (Denmark)

    Tosello, Guido; Hansen, Hans Nørgaard; Tang, Peter Torben

    2006-01-01

    was designed and manufactured by over-moulding and hot-embossing. The bonding strength between the insert and the plastic part was tested by means of a tensile test. A variety of parameters was studied in order to investigate their influence on the bonding: different polymeric and metallic materials, insert...... thickness, metal surface roughness and texture topography, surface treatment and coating, i.e. metal insert designs to improve polymer/metal interlocking and tensile test speed. Results show a strong influence of the surface properties and of the employed material on the bonding strength. The proposed...

  9. Glass-to-metal bonding process improves stability and performance of semiconductor devices

    Science.gov (United States)

    Trent, R. L.

    1970-01-01

    Anodic bonding of glass coverslips to photodiodes and photovoltaic devices eliminates the need for adhesive. The process requires relatively low temperatures /less than 560 degrees C/ and the metals and glass remain solid throughout the bonding process.

  10. Electrochemical sensors and devices for heavy metals assay in water: the French groups' contribution

    National Research Council Canada - National Science Library

    Pujol, Luca; Evrard, David; Groenen-Serrano, Karine; Freyssinier, Mathilde; Ruffien-Cizsak, Audrey; Gros, Pierre

    2014-01-01

    A great challenge in the area of heavy metal trace detection is the development of electrochemical techniques and devices which are user-friendly, robust, selective, with low detection limits and allowing fast analyses...

  11. The impact of common metal allergens in daily devices

    DEFF Research Database (Denmark)

    Hamann, Dathan; Hamann, Carsten R; Thyssen, Jacob P

    2013-01-01

    We are widely exposed to metal allergens in our daily doings. As exposures constantly changes because of fashion trends and technological developments, there is a need for a continuous update of patch testers. An overview of consumer metal exposure studies that have been published in 2012 and 2013...

  12. "Periodic-table-style" paper device for monitoring heavy metals in water.

    Science.gov (United States)

    Li, Miaosi; Cao, Rong; Nilghaz, Azadeh; Guan, Liyun; Zhang, Xiwang; Shen, Wei

    2015-03-03

    If a paper-based analytical device (μ-PAD) could be made by printing indicators for detection of heavy metals in chemical symbols of the metals in a style of the periodic table of elements, it could be possible for such μ-PAD to report the presence and the safety level of heavy metal ions in water simultaneously and by text message. This device would be able to provide easy solutions to field-based monitoring of heavy metals in industrial wastewater discharges and in irrigating and drinking water. Text-reporting could promptly inform even nonprofessional users of the water quality. This work presents a proof of concept study of this idea. Cu(II), Ni(II), and Cr(VI) were chosen to demonstrate the feasibility, specificity, and reliability of paper-based text-reporting devices for monitoring heavy metals in water.

  13. Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

    Science.gov (United States)

    Haaland, Carsten M.; Deeds, W. Edward

    1999-01-01

    A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output.

  14. Nanoscale decomposition of Nb-Ru-O

    Science.gov (United States)

    Music, Denis; Geyer, Richard W.; Chen, Yen-Ting

    2016-11-01

    A correlative theoretical and experimental methodology has been employed to explore the decomposition of amorphous Nb-Ru-O at elevated temperatures. Density functional theory based molecular dynamics simulations reveal that amorphous Nb-Ru-O is structurally modified within 10 ps at 800 K giving rise to an increase in the planar metal - oxygen and metal - metal population and hence formation of large clusters, which signifies atomic segregation. The driving force for this atomic segregation process is 0.5 eV/atom. This is validated by diffraction experiments and transmission electron microscopy of sputter-synthesized Nb-Ru-O thin films. Room temperature samples are amorphous, while at 800 K nanoscale rutile RuO2 grains, self-organized in an amorphous Nb-O matrix, are observed, which is consistent with our theoretical predictions. This amorphous/crystalline interplay may be of importance for next generation of thermoelectric devices.

  15. Nanoelectronic device applications handbook

    CERN Document Server

    Morris, James E

    2013-01-01

    Nanoelectronic Device Applications Handbook gives a comprehensive snapshot of the state of the art in nanodevices for nanoelectronics applications. Combining breadth and depth, the book includes 68 chapters on topics that range from nano-scaled complementary metal-oxide-semiconductor (CMOS) devices through recent developments in nano capacitors and AlGaAs/GaAs devices. The contributors are world-renowned experts from academia and industry from around the globe. The handbook explores current research into potentially disruptive technologies for a post-CMOS world.These include: Nanoscale advance

  16. Improving light harvesting in polymer photodetector devices through nanoindented metal mask films

    NARCIS (Netherlands)

    Macedo, A. G.; Zanetti, F.; Mikowski, A.; Hummelen, J. C.; Lepienski, C. M.; da Luz, M. G. E.; Roman, L. S.

    2008-01-01

    To enhance light harvesting in organic photovoltaic devices, we propose the incorporation of a metal (aluminum) mask film in the system's usual layout. We fabricate devices in a sandwich geometry, where the mask (nanoindented with a periodic array of holes of sizes d and spacing s) is added between

  17. Capability of tip-enhanced Raman spectroscopy about nanoscale analysis of strained silicon for semiconductor devices production

    Science.gov (United States)

    Lucia, Arianna; Cacioppo, Onofrio Antonino; Iulianella, Enrico; Latessa, Luca; Moccia, Giuseppe; Passeri, Daniele; Rossi, Marco

    2017-03-01

    Localized strained silicon was observed with a suitable resolution in a real semiconductor device by tip-enhanced Raman spectroscopy (TERS). The device was made via a standard industrial process and its silicon trench isolation structures were used for the silicon strain analysis obtaining results according to finite element method-based simulation data. We have achieved a reliable and repeatable enhancement factor obtaining a trace of strained silicon along the structure with suitable nanometer spatial resolution compatible with IC industry requirements. We demonstrate that the complexity to analyze a real 3D structure, directly from the production lines and not ad hoc realized, entails the challenges to individuate the optimal tip shape, tip contact angle, tip composition, tip positioning system, laser power, and wavelength to achieve an appropriate plasmon resonance inducing a relevant signal to noise ratio. This work gives the base to address the development in TERS optimization for real industrial applications.

  18. Nanoscale 2013

    Science.gov (United States)

    Koenders, Ludger; Ducourtieux, Sebastien

    2014-04-01

    The accurate determination of the properties of micro- and nano-structures is essential in research and development. It is also a prerequisite in process control and quality assurance in industry. In most cases, especially at the nanometer range, knowledge of the dimensional properties of structures is the fundamental base, to which further physical properties are linked. Quantitative measurements presuppose reliable and stable instruments, suitable measurement procedures as well as calibration artifacts and methods. This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2013 seminar held in Paris, France, on 25 and 26 April. It was the 6th Seminar on NanoScale Calibration Standards and Methods and the 10th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Nanometrology Group of the Technical Committee-Length of EURAMET, the Physikalisch-Technische Bundesanstalt and the Laboratoire National de Métrologie et d'Essais. Three satellite meetings related to nanometrology were coupled to the seminar. The first one was an open Symposium on Scanning Probe Microscopy Standardization organized by the ISO/TC 201/SC9 technical committee. The two others were specific meetings focused on two European Metrology Research Projects funded by the European Association of National Metrology Institutes (EURAMET) (see www.euramet.org), the first one focused on the improvement of the traceability for high accuracy devices dealing with sub-nm length measurement and implementing optical interferometers or capacitive sensors (JRP SIB08 subnano), the second one aiming to develop a new metrological traceability for the measurement of the mechanical properties of nano-objects (JRP NEW05 MechProNo). More than 100 experts from industry, calibration laboratories and metrology institutes from around the world joined the NanoScale 2013 Seminar to attend 23 oral and 64 poster

  19. Transferred metal electrode films for large-area electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jin-Guo [Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Medical Drive, Singapore S117456 (Singapore); Kam, Fong-Yu [Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); Chua, Lay-Lay [Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore)

    2014-11-10

    The evaporation of metal-film gate electrodes for top-gate organic field-effect transistors (OFETs) limits the minimum thickness of the polymer gate dielectric to typically more than 300 nm due to deep hot metal atom penetration and damage of the dielectric. We show here that the self-release layer transfer method recently developed for high-quality graphene transfer is also capable of giving high-quality metal thin-film transfers to produce high-performance capacitors and OFETs with superior dielectric breakdown strength even for ultrathin polymer dielectric films. Dielectric breakdown strengths up to 5–6 MV cm{sup −1} have been obtained for 50-nm thin films of polystyrene and a cyclic olefin copolymer TOPAS{sup ®} (Zeon). High-quality OFETs with sub-10 V operational voltages have been obtained this way using conventional polymer dielectrics and a high-mobility polymer semiconductor poly[2,5-bis(3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene-2,5-diyl]. The transferred metal films can make reliable contacts without damaging ultrathin polymer films, self-assembled monolayers and graphene, which is not otherwise possible from evaporated or sputtered metal films.

  20. Analysis of metallic medical devices after cremation: The importance in identification.

    Science.gov (United States)

    De Angelis, Danilo; Collini, Federica; Muccino, Enrico; Cappella, Annalisa; Sguazza, Emanuela; Mazzucchi, Alessandra; Cattaneo, Cristina

    2017-03-01

    The recovery of a charred cadaver raises many issues concerning personal identification; the presence of prosthetic materials may provide very important and decisive information. Who is involved in the recovery of a charred body or of burnt human fragments, should therefore be able to recognize medical devices even if modified by fire effects. Metallic residues (585kg) that came from 2785 cremations were studied. Medical devices were then divided by type and material in order to esteem the representativeness of each typology. The study illustrates the great presence of metal medical devices that could be of great help in identifying bodies and underlines that metallic medical devices types and morphology should be known by forensic practitioner involved in identification cases and that this kind of material can still be identified by physician and dentists, even if exposed to very high temperatures. Copyright © 2016 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

  1. Performance optimization of nanoscale junctionless transistors through varying device design parameters for ultra-low power logic applications

    Science.gov (United States)

    Roy, Debapriya; Biswas, Abhijit

    2016-09-01

    Ultra-low power logic applications at advanced CMOS technology nodes have been extensively investigated nowadays to increase packing density in Integrated Circuits at a lower cost. Junctionless (JL) transistors have emerged as promising alternatives to conventional MOSFETs because of their relatively easy fabrication steps and extreme scalability. We perform a detailed numerical study to evaluate the effects of channel doping concentration, dielectric constant of underlap spacers, source/drain resistance on logic performance of 20 nm gate length JL MOSFETs in terms of ON-current at a given OFF-current, subthreshold swing, gate capacitance and intrinsic delay for supply voltages ranging 0.4-0.75 V. In comparison with the reported experimental data for inversion-mode device, our optimized JL device exhibits enhancement of ION by 15.6%, reduction of drain-induced barrier lowering (DIBL) by 22.5% while preserving equally low SS of 61.5 mV/decade at channel length of 34 nm and supply voltage of 0.75 V.

  2. Electrolytic reduction of liquid metal oxides and its application to reconfigurable structured devices.

    Science.gov (United States)

    Wang, Jinqi; Appusamy, Kanagasundar; Guruswamy, Sivaraman; Nahata, Ajay

    2015-03-02

    Structured metallic patterns are routinely used for a wide variety of applications, ranging from electronic circuits to plasmonics and metamaterials. Numerous techniques have been developed for the fabrication of these devices, in which the metal patterns are typically formed using conventional metals. While this approach has proven very successful, it does generally limit the ability to reconfigure the geometry of the overall device. Here, we demonstrate the ability to create artificially structured metallic devices using liquid metals, in which the configuration can be altered via the electrolysis of saline solutions or deionized water. We accomplish this using an elastomeric mold with two different sets of embedded microfluidic channels that are patterned and injected with EGaIn and water, respectively. The electrochemical reaction is then used to etch the thin oxide layer that forms on eutectic gallium indium (EGaIn) in a controlled reproducible manner. Once the oxide layer is dissolved locally, the underlying liquid metal retracts away from the original position to a position where a new stable oxide layer can reform, which is equivalent to erasing a section of the liquid metal. To allow for full reconfigurability, the entire device can be reset by refilling all of the microchannels with EGaIn.

  3. Phase-selective chemical extraction of selenium and sulfur from nanoscale metal chalcogenides: a general strategy for synthesis, purification, and phase targeting.

    Science.gov (United States)

    Sines, Ian T; Schaak, Raymond E

    2011-02-09

    Controlling the composition and phase formation of bulk and nanoscale solids underpins efforts to control physical properties. Here, we introduce a powerful new chemical pathway that facilitates composition-tunable synthesis, post-synthesis purification, and precise phase targeting in metal chalcogenide systems. When metal selenides and sulfides react with trioctylphosphine (TOP) at temperatures that range from 65 to 270 °C, selenium and sulfur are selectively extracted to produce the most metal-rich chalcogenide that is stable in a particular binary system. This general approach is demonstrated for SnSe(2), FeS(2), NiSe(2), and CoSe(2), which convert to SnSe, FeS, Ni(3)Se(2), and Co(9)Se(8), respectively. In-depth studies of the Fe-Se system highlight the precise phase targeting and purification that is achievable, with PbO-type FeSe (the most metal-rich stable Fe-Se phase) forming exclusively when other Fe-Se phases, including mixtures, react with TOP. This chemistry also represents a new template-based nanoparticle "conversion chemistry" reaction, transforming hollow NiSe(2) nanospheres into hollow NiSe nanospheres with morphological retention.

  4. Catalytic Conversion of Short-Chain Alcohols on Atomically Dispersed Au and Pd Supported on Nanoscale Metal Oxides

    Science.gov (United States)

    Wang, Chongyang

    With the development of technologies for cellulosic biomass conversion to fuels and chemicals, bio-alcohols are among the main alternative feedstocks to fossil fuels. The research pursued in my thesis was the investigation of gold and palladium as catalysts for the application of short aliphatic alcohols to hydrogen generation and value-added chemicals production. Specifically, selective methanol steam reforming and non-oxidative ethanol dehydrogenation to hydrogen and acetaldehyde were investigated in this thesis work. A major aim of the thesis was to develop atomically efficient catalysts with tuned surface chemistry for the desired reactions, using suitable synthesis methods. Methanol steam reforming (SRM) for hydrogen production has recently been investigated on gold catalysts to overcome the drawbacks of copper catalysts (deactivation, pyrophoricity). Previous work at Tufts University has shown that both CeO2 and ZnO are suitable supports for gold. In this thesis, nanoscale composite oxides ZnZrOx were prepared by a carbon hard-template method, which resulted in homogeneous distribution of Zn species in the matrix of ZrO2. Tunable surface chemistry of ZnZrO x was demonstrated by varying the Zn/Zr ratio to suppress the strong Lewis acidity of ZrO2, which leads to undesired production of CO through methanol decomposition. With atomic dispersion of gold, Au/ZnZrO x catalyzes the SRM reaction exclusively via the methanol self-coupling pathway up to 375°C. The activity of Au/ZnZrOx catalysts was compared to Au/TiO2, which is another catalyst system demonstrating atomic dispersion of gold. Similarity in the apparent activation energy of SRM on all the supported gold catalysts studied in this thesis and in the literature further confirms the same single-site Au-Ox-MO centers as active sites for SRM with indirect effects of the supports exploited. With this fundamental understanding of gold-catalyzed C1 alcohol reforming, the Au/ZnZrOx catalyst was evaluated for the

  5. Surface nanoscale axial photonics

    CERN Document Server

    Sumetsky, M

    2011-01-01

    Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger equation. These modes can be steered with dramatically small nanoscale variation of the fiber radius, which is quite simple to introduce in practice. The extremely low loss of SNAP devices is achieved due to the fantastically low surface roughness inherent in a drawn fiber surface. In excellent agreement with the developed theory, we experimentally demonstrate localization of light in quantum wells, halting light by a point source, tunneling through potential barriers, dark states, etc. This demonstration, prototyping basi...

  6. Nanoscale technology in biological systems

    CERN Document Server

    Greco, Ralph S; Smith, R Lane

    2004-01-01

    Reviewing recent accomplishments in the field of nanobiology Nanoscale Technology in Biological Systems introduces the application of nanoscale matrices to human biology. It focuses on the applications of nanotechnology fabrication to biomedical devices and discusses new physical methods for cell isolation and manipulation and intracellular communication at the molecular level. It also explores the application of nanobiology to cardiovascular diseases, oncology, transplantation, and a range of related disciplines. This book build a strong background in nanotechnology and nanobiology ideal for

  7. Metal nanoparticle mediated space charge and its optical control in an organic hole-only device

    Energy Technology Data Exchange (ETDEWEB)

    Ligorio, G.; Nardi, M. V. [Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor Str. 6, 12489 Berlin (Germany); Steyrleuthner, R.; Neher, D. [Institute of Physics and Astronomy, Universität Potsdam, Karl-Liebknecht Str. 24, 14476 Potsdam (Germany); Ihiawakrim, D. [Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, 67034 Strasbourg, Cedex2 (France); Crespo-Monteiro, N.; Brinkmann, M. [Institut Charles Sadron CNRS, 23 rue du Loess, 67034 Strasbourg (France); Koch, N., E-mail: norbert.koch@physik.hu-berlin.de [Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor Str. 6, 12489 Berlin (Germany); Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Erneuerbare Energien, Albert-Einstein Str. 15, 12489 Berlin (Germany)

    2016-04-11

    We reveal the role of localized space charges in hole-only devices based on an organic semiconductor with embedded metal nanoparticles (MNPs). MNPs act as deep traps for holes and reduce the current density compared to a device without MNPs by a factor of 10{sup 4} due to the build-up of localized space charge. Dynamic MNPs charged neutrality can be realized during operation by electron transfer from excitons created in the organic matrix, enabling light sensing independent of device bias. In contrast to the previous speculations, electrical bistability in such devices was not observed.

  8. Alcohol-Mediated Resistance-Switching Behavior in Metal-Organic Framework-Based Electronic Devices.

    Science.gov (United States)

    Liu, Yaqing; Wang, Hong; Shi, Wenxiong; Zhang, Weina; Yu, Jiancan; Chandran, Bevita K; Cui, Chenlong; Zhu, Bowen; Liu, Zhiyuan; Li, Bin; Xu, Cai; Xu, Zhiling; Li, Shuzhou; Huang, Wei; Huo, Fengwei; Chen, Xiaodong

    2016-07-25

    Metal-organic frameworks (MOFs) have drawn increasing attentions as promising candidates for functional devices. Herein, we present MOF films in constructing memory devices with alcohol mediated resistance switching property, where the resistance state is controlled by applying alcohol vapors to achieve multilevel information storage. The ordered packing mode and the hydrogen bonding system of the guest molecules adsorbed in MOF crystals are shown to be the reason for the alcohol mediated electrical switching. This chemically mediated memory device can be a candidate in achieving environment-responsive devices and exhibits potential applications in wearable information storage systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Nanopatterned Metallic Films for Use As Transparent Conductive Electrodes in Optoelectronic Devices

    KAUST Repository

    Catrysse, Peter B.

    2010-08-11

    We investigate the use of nanopatterned metallic films as transparent conductive electrodes in optoelectronic devices. We find that the physics of nanopatterned electrodes, which are often optically thin metallic films, differs from that of optically thick metallic films. We analyze the optical properties when performing a geometrical transformation that maintains the electrical properties. For one-dimensional patterns of metallic wires, the analysis favors tall and narrow wires. Our design principles remain valid for oblique incidence and readily carry over to two-dimensional patterns. © 2010 American Chemical Society.

  10. Metallization and packaging of compound semiconductor devices at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Seigal, P.K.; Armendariz, M.G.; Rieger, D.J.; Lear, K.L.; Sullivan, C.T.

    1996-11-01

    Recent advances in compound semiconductor technology utilize a variety of metal thin films fabricated by thermal and electron-beam evaporation, and electroplating. An overview of metal processes used by Sandia`s Compound Semiconductor Research Laboratory is presented. Descriptions of electrical n-type and p-type ohmic contact alloys, interconnect metal, and metal layers specifically included for packaging requirements are addressed. Several illustrations of devices incorporating gold plated air bridges are included. ``Back-end`` processes such as flip-chip under bump metallurgy with fluxless solder reflow and plated solder processes are mentioned as current research areas.

  11. Electroanalysis at the nanoscale.

    Science.gov (United States)

    Dawson, Karen; O'Riordan, Alan

    2014-01-01

    This article reviews the state of the art of silicon chip-based nanoelectrochemical devices for sensing applications. We first describe analyte mass transport to nanoscale electrodes and emphasize understanding the importance of mass transport for the design of nanoelectrode arrays. We then describe bottom-up and top-down approaches to nanoelectrode fabrication and integration at silicon substrates. Finally, we explore recent examples of on-chip nanoelectrodes employed as sensors and diagnostics, finishing with a brief look at future applications.

  12. Effect of nanoscale zero-valent iron and magnetite (Fe3O4) on the fate of metals during anaerobic digestion of sludge.

    Science.gov (United States)

    Suanon, Fidèle; Sun, Qian; Mama, Daouda; Li, Jiangwei; Dimon, Biaou; Yu, Chang-Ping

    2016-01-01

    Anaerobic digestion (AD) is one of the most widely used processes to stabilize waste sewage sludge and produce biogas renewable energy. In this study, two different iron nanoparticles [nanoscale zero-valent iron (nZVI) and magnetite (Fe3O4)] were used in the mesophilic AD processes (37 ± 1 °C) to improve biogas production. In addition, changes of heavy metal (Cd, Co, Cu, Zn, Ni and Cr) speciation during AD of sludge with and without iron nanoparticles have been investigated. Concentrations of metals in the initial sludge were as follows: 63.1, 73.4, 1102.2, 2060.3, 483.9 and 604.1 mg kg(-1) (dry sludge basis) for Cd, Co, Cu, Zn, Ni and Cr, respectively. Sequential fractionation showed that metals were predominantly bonded to organic matter and carbonates in the initial sludge. Compared with AD without iron nanoparticles, the application of iron nanoparticles (at dose of 0.5% in this study) showed positive impact not only on biogas production, but also on improvement of metals stabilization in the digestate. Metals were found concentrated in Fe-Mn bound and residual fractions and little was accumulated in the liquid digestate and most mobile fractions of solid digestate (water soluble, exchangeable and carbonates bound). Therefore, iron nanoparticles when properly used, could improve not only biogas yield, but also regulate and control the mobilization of metals during AD process. However, our study also observed that iron nanoparticles could promote the immobilization of phosphorus within the sludge during AD, and more research is needed to fully address the mechanism behind this phenomenon and the impact on future phosphorus reuse. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Elaboration of Prussian Blue Analogue/Silica Nanocomposites: Towards Tailor-Made Nano-Scale Electronic Devices

    Directory of Open Access Journals (Sweden)

    Anne Bleuzen

    2012-03-01

    Full Text Available The research of new molecular materials able to replace classical solid materials in electronics has attracted growing attention over the past decade. Among these compounds photoswitchable Prussian blue analogues (PBA are particularly interesting for the elaboration of new optical memories. However these coordination polymers are generally synthesised as insoluble powders that cannot be integrated into a real device. Hence their successful integration into real applications depends on an additional processing step. Nanostructured oxides elaborated by sol-gel chemistry combined with surfactant micelle templating can be used as nanoreactors to confine PBA precipitation and organize the functional nano-objects in the three dimensions of space. In this work we present the elaboration of different CoFe PBA/silica nanocomposites. Our synthetic procedure fully controls the synthesis of PBA in the porosity of the silica matrix from the insertion of the precursors up to the formation of the photomagnetic compound. We present results on systems from the simplest to the most elaborate: from disordered xerogels to ordered nanostructured films passing through mesoporous monoliths.

  14. Polymer/metal hybrid multilayers modified Schottky devices

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, V.; Isgrò, G.; Li Destri, G.; Marletta, G. [Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania and CSGI, Viale A. Doria 6, 95125 Catania (Italy); Ruffino, F.; Grimaldi, M. G. [Dipartimento di Fisica ed Astronomia-Università di Catania, via S. Sofia 64, 95123 Catania (Italy); MATIS IMM-CNR, via S. Sofia 64, 95123 Catania (Italy); Crupi, I. [MATIS IMM-CNR, via S. Sofia 64, 95123 Catania (Italy)

    2013-11-04

    Insulating, polymethylmethacrylate (PMMA), and semiconducting, poly(3-hexylthiophene) (P3HT), nanometer thick polymers/Au nanoparticles based hybrid multilayers (HyMLs) were fabricated on p-Si single-crystal substrate. An iterative method, which involves, respectively, spin-coating (PMMA and P3HT deposition) and sputtering (Au nanoparticles deposition) techniques to prepare Au/HyMLs/p-Si Schottky device, was used. The barrier height and the ideality factor of the Au/HyMLs/p-Si Schottky devices were investigated by current-voltage measurements in the thickness range of 1–5 bilayers. It was observed that the barrier height of such hybrid layered systems can be tuned as a function of bilayers number and its evolution was quantified and analyzed.

  15. Photochemical deterioration of the organic/metal contacts in organic optoelectronic devices

    Science.gov (United States)

    Wang, Qi; Williams, Graeme; Tsui, Ting; Aziz, Hany

    2012-09-01

    We study the effect of exposure to light on a wide range of organic/metal contacts that are commonly used in organic optoelectronic devices and found that irradiation by light in the visible and UV range results in a gradual deterioration in their electrical properties. This photo-induced contact degradation reduces both charge injection (i.e., from the metal to the organic layer) and charge extraction (i.e., from the organic layer to the metal). X-ray photoelectron spectroscopy (XPS) measurements reveal detectable changes in the interface characteristics after irradiation, indicating that the photo-degradation is chemical in nature. Changes in XPS characteristics after irradiation suggests a possible reduction in bonds associated with organic-metal complexes. Measurements of interfacial adhesion strength using the four-point flexure technique reveal a decrease in organic/metal adhesion in irradiated samples, consistent with a decrease in metal-organic bond density. The results shed the light on a new material degradation mechanism that appears to have a wide presence in organic/metal interfaces in general, and which likely plays a key role in limiting the stability of various organic optoelectronic devices such as organic light emitting devices, organic solar cells, and organic photo-detectors.

  16. Optical Spectroscopy at the Nanoscale

    Science.gov (United States)

    Hong, Xiaoping

    Recent advances in material science and fabrication techniques enabled development of nanoscale applications and devices with superior performances and high degree of integration. Exotic physics also emerges at nanoscale where confinement of electrons and phonons leads to drastically different behavior from those in the bulk materials. It is therefore rewarding and interesting to investigate and understand material properties at the nanoscale. Optical spectroscopy, one of the most versatile techniques for studying material properties and light-matter interactions, can provide new insights into the nanomaterials. In this thesis, I explore advanced laser spectroscopic techniques to probe a variety of different nanoscale phenomena. A powerful tool in nanoscience and engineering is scanning tunneling microscopy (STM). Its capability in atomic resolution imaging and spectroscopy unveiled the mystical quantum world of atoms and molecules. However identification of molecular species under investigation is one of the limiting functionalities of the STM. To address this need, we take advantage of the molecular `fingerprints' - vibrational spectroscopy, by combining an infrared light sources with scanning tunneling microscopy. In order to map out sharp molecular resonances, an infrared continuous wave broadly tunable optical parametric oscillator was developed with mode-hop free fine tuning capabilities. We then combine this laser with STM by shooting the beam onto the STM substrate with sub-monolayer diamondoids deposition. Thermal expansion of the substrate is detected by the ultrasensitive tunneling current when infrared frequency is tuned across the molecular vibrational range. Molecular vibrational spectroscopy could be obtained by recording the thermal expansion as a function of the excitation wavelength. Another interesting field of the nanoscience is carbon nanotube, an ideal model of one dimensional physics and applications. Due to the small light absorption with

  17. Electrochemistry at nanoscale electrodes: individual single-walled carbon nanotubes (SWNTs) and SWNT-templated metal nanowires.

    Science.gov (United States)

    Dudin, Petr V; Snowden, Michael E; Macpherson, Julie V; Unwin, Patrick R

    2011-12-27

    Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30-70 μm, filled with solution containing a redox-active mediator (FcTMA(+) ((trimethylammonium)methylferrocene), Fe(CN)(6)(4-), or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler-Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k(0), up to ca. 1 cm s(-1) can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA(+/2+) electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k(0) > 2 ± 1 cm s(-1)). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale.

  18. Effect of promoter and noble metals and suspension pH on catalytic nitrate reduction by bimetallic nanoscale Fe(0) catalysts.

    Science.gov (United States)

    Bae, Sungjun; Hamid, Shanawar; Jung, Junyoung; Sihn, Youngho; Lee, Woojin

    2016-01-01

    Experiments were conducted to investigate the effect of experimental factors (types of promotor and noble metals, H2 injection, and suspension pH) on catalytic nitrate reduction by bimetallic catalysts supported by nanoscale zero-valent iron (NZVI). NZVI without H2 injection showed 71% of nitrate reduction in 1 h. Cu/NZVI showed the almost complete nitrate reduction (96%) in 1 h, while 67% of nitrate was reduced by Ni/NZVI. The presence of noble metals (Pd and Pt) on Cu/NZVI without H2 injection resulted in the decrease of removal efficiency to 89% and 84%, respectively, due probably to the electron loss of NZVI for formation of metallic Pd and Pt. H2 injection into Cu-Pd/NZVI suspension significantly improved both catalytic nitrate reduction (>97% in 30 min) and N2 selectivity (18%), indicating that adsorbed H on active Pd sites played an important role for the enhanced nitrate reduction and N2 selectivity. The rapid passivation of NZVI surface resulted in a dramatic decrease in nitrate reduction (79-28%) with an increase in N2 selectivity (8-66%) as the suspension pH increased from 8 to 10.

  19. Multidisciplinary emergent removal of a metal penoscrotal constriction device

    LENUS (Irish Health Repository)

    Nason, GJ

    2017-03-01

    Strangulation of the genital organs is a rare presentation to the emergency department which requires urgent intervention to avoid long term complications. Penoscrotal constriction devices are either used for autoerotic stimulus or to increase sexual performance by maintaining an erection for a longer period. We report a case of a man who presented with penile strangulation following the application of a titanium penoscrotal constriction ring during sexual intercourse seven hours previously. The Fire Brigade department attended with an electric operated angle grinder to facilitate removal of the ring as standard medical equipment (orthopaedic saws, bolt and bone cutters) were insufficient. Fully functional recovery was achieved.

  20. Biomaterial-based Memory Device Development by Conducting Metallic DNA

    Science.gov (United States)

    2013-05-28

    basis of the redshift of UV absorption spectra, we think that the incorporation of metal ions may result in a reduction of the original DNA band gap ...memristor based on the changing of the boundary between the high-resistance and low-resistance layers of titanium dioxide TiO2 and TiO2 -x13. Their...microscope (FESEM, JEOL JSM-6500F ) was used to measure the morphology of patterned substrate. The gap width and length between electrodes are both

  1. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    Science.gov (United States)

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  2. Positioning of the Fermi Level in Graphene Devices with Asymmetric Metal Electrodes

    Directory of Open Access Journals (Sweden)

    Bum-Kyu Kim

    2010-01-01

    Full Text Available To elucidate the effect of the work function on the position of the Dirac point, we fabricated graphene devices with asymmetric metal contacts. By measuring the peak position of the resistance for each pair of metal electrodes, we obtained the voltage of the Dirac point VgDirac (V from the gate response. We found that the position of VgDirac (V in the hybrid devices was significantly influenced by the type of metal electrode. The measured shifts in VgDirac (V were closely related to the modified work functions of the metal-graphene complexes. Within a certain bias range, the Fermi level of one of the contacts aligned with the electron band and that of the other contact aligned with the hole band.

  3. The abnormal electrostatic discharge of a no-connect metal cover in a ceramic packaging device

    Institute of Scientific and Technical Information of China (English)

    Li Song; Zeng Chuanbin; Luo Jiajun; Han Zhengsheng

    2013-01-01

    The human body model (HBM) stress of a no-connect metal cover is tested to obtain the characteristics of abnormal electrostatic discharge,including current waveforms and peak current under varied stress voltage and device failure voltage.A new discharge model called the "sparkover-induced model" is proposed based on the results.Then,failure mechanism analysis and model simulation are performed to prove that the transient peak current caused by a sparkover of low arc impedance will result in the devices' premature damage when the potential difference between the no-connect metal cover and the chip exceeds the threshold voltage of sparkover.

  4. Investigations of the Impact of Biodiesel Metal Contaminants on Emissions Control Devices

    Energy Technology Data Exchange (ETDEWEB)

    Brookshear, D. W.; Lance, M. J.; McCormick, Robert L.; Toops, T. J.

    2017-02-27

    Biodiesel is a renewable fuel with the potential to displace a portion of petroleum use. However, as with any alternative fuel, in order to be a viable choice it must be compatible with the emissions control devices. The finished biodiesel product can contain up to 5 ppm Na+K and 5 ppm Ca+Mg, and these metal impurities can lead to durability issues with the devices used to control emissions in diesel vehicles. Significant work has been performed to understand how the presence of these metals impacts each individual component of diesel emissions control systems, and this chapter summarizes the findings of these research efforts.

  5. Investigations of the Impact of Biodiesel Metal Contaminants on Emissions Control Devices

    Energy Technology Data Exchange (ETDEWEB)

    Brookshear, Daniel W [ORNL; Lance, Michael J [ORNL; Mccormick, Robert [National Renewable Energy Laboratory (NREL); Toops, Todd J [ORNL

    2017-01-01

    Biodiesel is a renewable fuel with the potential to displace a portion of petroleum use. However, as with any alternative fuel, in order to be a viable choice it must be compatible with the emissions control devices. The finished biodiesel product can contain up to 5 ppm Na + K and 5 ppm Ca + Mg, and these metal impurities can lead to durability issues with the devices used to control emissions in diesel vehicles. Significant work has been performed to understand how the presence of these metals impacts each individual component of diesel emissions control systems, and this chapter summarizes the findings of these research efforts.

  6. Natural radioactivity consideration for high- dielectrics and metal gates choice in nanoelectronic devices

    OpenAIRE

    Gedion, Michael; Wrobel, Frédéric; Saigné, Frédéric

    2010-01-01

    Abstract In order to face downscaling, new chemical elements are used and suggested for the semiconductor industry. However, some of these elements have natural radioactive isotopes, which may cause reliability issues in nanoelectronic devices by triggering soft errors. In this paper, we focus on high-? dielectric materials and metal gates. We show that beside physical, chemical and mechanical properties of high-? dielectrics and metal gates, natural radioactivity is also a crucial propert...

  7. Robust Pressure-Actuated Liquid Metal Devices Showing Reconfigurable Electromagnetic Effects at GHz Frequencies (POSTPRINT)

    Science.gov (United States)

    2014-06-01

    actuated liquid metal devices are demonstrated for reconfigurable electromagnetic fundamentals at GHz frequencies, including tunable dipole antennas ...Mazlouman, A. Mahanfar, C. Menon et al., “Mechanically Reconfigurable Antennas using Electro-active Polymers (EAPs),” 2011 Ieee International Symposium...on Antennas and Propagation (Apsursi), pp. 742-745, 2011. [3] B. Cumby, G. Hayes, M. Dickey et al., “ Reconfigurable liquid metal circuits by

  8. Synthesis, dynamics and photophysics of nanoscale systems

    Science.gov (United States)

    Mirkovic, Tihana

    The emerging field of nanotechnology, which spans diverse areas such as nanoelectronics, medicine, chemical and pharmaceutical industries, biotechnology and computation, focuses on the development of devices whose improved performance is based on the utilization of self-assembled nanoscale components exhibiting unique properties owing to their miniaturized dimensions. The first phase in the conception of such multifunctional devices based on integrated technologies requires the study of basic principles behind the functional mechanism of nanoscale components, which could originate from individual nanoobjects or result as a collective behaviour of miniaturized unit structures. The comprehensive studies presented in this thesis encompass the mechanical, dynamical and photophysical aspects of three nanoscale systems. A newly developed europium sulfide nanocrystalline material is introduced. Advances in synthetic methods allowed for shape control of surface-functionalized EuS nanocrystals and the fabrication of multifunctional EuS-CdSe hybrid particles, whose unique structural and optical properties hold promise as useful attributes of integrated materials in developing technologies. A comprehensive study based on a new class of multifunctional nanomaterials, derived from the basic unit of barcoded metal nanorods is presented. Their chemical composition affords them the ability to undergo autonomous motion in the presence of a suitable fuel. The nature of their chemically powered self-propulsion locomotion was investigated, and plausible mechanisms for various motility modes were presented. Furthermore functionalization of striped metallic nanorods has been realized through the incorporation of chemically controlled flexible hinges displaying bendable properties. The structural aspect of the light harvesting machinery of a photosynthetic cryptophyte alga, Rhodomonas CS24, and the mobility of the antenna protein, PE545, in vivo were investigated. Information obtained

  9. Metal-organic molecular device for non-volatile memory storage

    Energy Technology Data Exchange (ETDEWEB)

    Radha, B., E-mail: radha.boya@manchester.ac.uk, E-mail: kulkarni@jncasr.ac.in; Sagade, Abhay A.; Kulkarni, G. U., E-mail: radha.boya@manchester.ac.uk, E-mail: kulkarni@jncasr.ac.in [Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)

    2014-08-25

    Non-volatile memory devices have been of immense research interest for their use in active memory storage in powered off-state of electronic chips. In literature, various molecules and metal compounds have been investigated in this regard. Molecular memory devices are particularly attractive as they offer the ease of storing multiple memory states in a unique way and also represent ubiquitous choice for miniaturized devices. However, molecules are fragile and thus the device breakdown at nominal voltages during repeated cycles hinders their practical applicability. Here, in this report, a synergetic combination of an organic molecule and an inorganic metal, i.e., a metal-organic complex, namely, palladium hexadecylthiolate is investigated for memory device characteristics. Palladium hexadecylthiolate following partial thermolysis is converted to a molecular nanocomposite of Pd(II), Pd(0), and long chain hydrocarbons, which is shown to exhibit non-volatile memory characteristics with exceptional stability and retention. The devices are all solution-processed and the memory action stems from filament formation across the pre-formed cracks in the nanocomposite film.

  10. Nanoscale thermal transport. II. 2003–2012

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, David G., E-mail: d-cahill@illinois.edu; Braun, Paul V. [Department of Materials Science and Engineering and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Chen, Gang [Department of Mechanical Engineering, MIT, Cambridge, Massachusetts 02139 (United States); Clarke, David R. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Fan, Shanhui [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Goodson, Kenneth E. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Keblinski, Pawel [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); King, William P. [Department of Mechanical Sciences and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Mahan, Gerald D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States); Majumdar, Arun [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Maris, Humphrey J. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Phillpot, Simon R. [Department of Materials Science and Engineering, University of Florida, Gainseville, Florida 32611 (United States); Pop, Eric [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Shi, Li [Department of Mechanical Engineering, University of Texas, Autin, Texas 78712 (United States)

    2014-03-15

    A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ∼1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and

  11. Osseointegration of metallic devices: current trends based on implant hardware design.

    Science.gov (United States)

    Coelho, Paulo G; Jimbo, Ryo

    2014-11-01

    Osseointegration of metallic devices has been one of the most successful treatments in rehabilitative dentistry and medicine over the past five decades. While highly successful, the quest for designing surgical instrumentation and associated implantable devices that hastens osseointegration has been perpetual and has often been approached as single variable preclinical investigations. The present manuscript presents how the interplay between surgical instrumentation and device macrogeometry not only plays a key role on both early and delayed stages of osseointegration, but may also be key in how efficient smaller length scale designing (at the micrometer and nanometer scale levels) may be in hastening early stages of osseointegration. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Conformal, Nanoscale ZnO Surface Modification of Garnet-Based Solid-State Electrolyte for Lithium Metal Anodes.

    Science.gov (United States)

    Wang, Chengwei; Gong, Yunhui; Liu, Boyang; Fu, Kun; Yao, Yonggang; Hitz, Emily; Li, Yiju; Dai, Jiaqi; Xu, Shaomao; Luo, Wei; Wachsman, Eric D; Hu, Liangbing

    2017-01-11

    Solid-state electrolytes are known for nonflammability, dendrite blocking, and stability over large potential windows. Garnet-based solid-state electrolytes have attracted much attention for their high ionic conductivities and stability with lithium metal anodes. However, high-interface resistance with lithium anodes hinders their application to lithium metal batteries. Here, we demonstrate an ultrathin, conformal ZnO surface coating by atomic layer deposition for improved wettability of garnet solid-state electrolytes to molten lithium that significantly decreases the interface resistance to as low as ∼20 Ω·cm(2). The ZnO coating demonstrates a high reactivity with lithium metal, which is systematically characterized. As a proof-of-concept, we successfully infiltrated lithium metal into porous garnet electrolyte, which can potentially serve as a self-supported lithium metal composite anode having both high ionic and electrical conductivity for solid-state lithium metal batteries. The facile surface treatment method offers a simple strategy to solve the interface problem in solid-state lithium metal batteries with garnet solid electrolytes.

  13. Anisotropic magnetostrictive metal-polymer composites for functional devices

    Science.gov (United States)

    Kiseleva, T. Yu.; Zholudev, S. I.; Il'inykh, I. A.; Novakova, A. A.

    2013-12-01

    New metal-polymer composites based on mechanochemically synthesized magnetostrictive Fe-Ga phase particles with dimensions of up to 2 μm dispersed and spatially oriented in a polymer matrix have been studied. The polymer matrix for spatial anisotropic stabilization of particles was represented by modified polyurethane (PU). An increase in the magnetostrictive effect was achieved by directed orientation of particles in a magnetic field applied during polymerization of the PU matrix. The spatial anisotropy of the composite has been studied by the methods of conversion Mössbauer spectroscopy with resonant X-ray detection and scanning electron microscopy. It is shown that the mechanochemical synthesis is an effective method of obtaining particles with microstress-enhanced magnetostriction. The use of these particles for the formation of a functional elastomer composite provides a material with significant magnetostrictive effect, which can be several-fold increased due to orientation of particles in an applied magnetic field. The obtained anisotropic magnetostrictive composite is a promising material for the creation of smart functional components of positioning systems, attenuators, and sensors.

  14. Research and development of metals for medical devices based on clinical needs

    Directory of Open Access Journals (Sweden)

    Takao Hanawa

    2012-01-01

    Full Text Available The current research and development of metallic materials used for medicine and dentistry is reviewed. First, the general properties required of metals used in medical devices are summarized, followed by the needs for the development of α + β type Ti alloys with large elongation and β type Ti alloys with a low Young's modulus. In addition, nickel-free Ni–Ti alloys and austenitic stainless steels are described. As new topics, we review metals that are bioabsorbable and compatible with magnetic resonance imaging. Surface treatment and modification techniques to improve biofunctions and biocompatibility are categorized, and the related problems are presented at the end of this review. The metal surface may be biofunctionalized by various techniques, such as dry and wet processes. These techniques make it possible to apply metals to scaffolds in tissue engineering.

  15. Research and development of metals for medical devices based on clinical needs

    Science.gov (United States)

    Hanawa, Takao

    2012-12-01

    The current research and development of metallic materials used for medicine and dentistry is reviewed. First, the general properties required of metals used in medical devices are summarized, followed by the needs for the development of α + β type Ti alloys with large elongation and β type Ti alloys with a low Young's modulus. In addition, nickel-free Ni-Ti alloys and austenitic stainless steels are described. As new topics, we review metals that are bioabsorbable and compatible with magnetic resonance imaging. Surface treatment and modification techniques to improve biofunctions and biocompatibility are categorized, and the related problems are presented at the end of this review. The metal surface may be biofunctionalized by various techniques, such as dry and wet processes. These techniques make it possible to apply metals to scaffolds in tissue engineering.

  16. Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

    DEFF Research Database (Denmark)

    Hansen, Christian Rein; Sørensen, Thomas Just; Glyvradal, Magni

    2009-01-01

    By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir-Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 Å titanium and 100 Å aluminum...

  17. Probing Interaction Between Platinum Group Metal (PGM) and Non-PGM Support Through Surface Characterization and Device Performance

    Science.gov (United States)

    Saha, Shibely

    High cost and limited abundance of Platinum (Pt) have hindered effective commercialization of Proton Exchange Membrane Fuel Cell and Electrolyzer. Efforts have been undertaken to reduce precious group metal (PGM) requirement for these devices without compromising the activity of the catalyst by using transition metal carbides (TMC) as non-PGM support thanks to their similar electronic and geometric structures as Pt. In this work Mo2C was selected as non-PGM support and Pt was used as the PGM of interest. We hypothesize that the hollow nanotube morphology of Mo2C support combined with Pt nano particles deposited on it via atomic layer deposition (ALD) technique would allow increased interaction between them which may increase the activity of Pt and Mo2C as well as maximize the Pt active surface area. Specifically, a rotary ALD equipment was used to grow Pt particles from atomic level to 2--3 nanometers by simply adjusting number of ALD cycles in order to probe the interaction between the deposited Pt nanoparticles and Mo2C nanotube support. Interaction between the Pt and Mo2 C was analyzed via surface characterization and electrochemical characterization. Interaction between Pt and Mo2C arises due to the lattice mismatch between Pt and Mo2C as well as electron migration between them. Lattice spacing analysis using high resolution transmission electron microscopy (HRTEM) images, combined with Pt binding energy shift in XPS results, clearly showed strong bonding between Pt nanoparticles and the Mo2C nanotube support in all the resultant Pt/Mo2C samples. We postulate that this strong interaction is responsible for the significantly enhanced durability observed in our constant potential electrolysis (CPE) and accelerated degradation testing (ADT). Of the three samples from different ALD cycles (15, 50 and 100), Mo2C nanotubes modified by 50 (1.07 wt% Pt loading) and 100 cycles (4.4 wt% Pt) of Pt deposition, showed higher HER and HOR activity per Pt mass than commercial

  18. Metal-free, single-polymer device exhibits resistive memory effect

    KAUST Repository

    Bhansali, Unnat Sampatraj

    2013-12-23

    All-polymer, write-once-read-many times resistive memory devices have been fabricated on flexible substrates using a single polymer, poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Spin-cast or inkjet-printed films of solvent-modified PEDOT:PSS are used as electrodes, while the unmodified or as-is PEDOT:PSS is used as the semiconducting active layer. The all-polymer devices exhibit an irreversible but stable transition from a low resistance state (ON) to a high resistance state (OFF) at low voltages caused by an electric-field-induced morphological rearrangement of PEDOT and PSS at the electrode interface. However, in the metal-PEDOT:PSS-metal devices, we have shown a metal filament formation switching the device from an initial high resistance state (OFF) to the low resistance state (ON). The all-PEDOT:PSS memory device has low write voltages (<3 V), high ON/OFF ratio (>10 3), good retention characteristics (>10 000 s), and stability in ambient storage (>3 months). © 2013 American Chemical Society.

  19. New urea sensor based on a metal island coated ion sensitive swelling polymer device

    Science.gov (United States)

    Schalkhammer, Thomas G. M.; Lobmaier, Christina; Pittner, Fritz; Leitner, Alfred; Brunner, Harald; Aussenegg, Franz R.

    1995-09-01

    An optical reflectivity change induced by a change of the micro environment around metal island is used to construct various sensors and biosensors. To obtain a sensitive micro sensor either the island density at the surface of the sensor device or the distance of an island layer film to a solid metal surface or to another island film can be varied. Polyvinylpyrrolidone crosslinked with sulfonated bisazidostilbenes shows chaotropic ion dependent nanometric shrinking and swelling which can be observed by using this polymer as interlayer in a metal island device. This volume change of the sensing polymer is transduced to an optical signal using a metal island film, followed by a thin layer of an optically transparent welling polymer and a further metal island film as the topmost layer, exposed to the analyte. This new set-up enables the spectroscopic monitoring of the reflectance change from the backside of the sensor chip not exposed to the analyte solution. For the construction of a biosensor the device was either covered by a photo-structured polyvinylpyrrolidone membrane incorporating the desired enzymes or combined with a micro enzyme reactor. The fully reversible response of the sensor is induced by carbonate and ammonium ions liberated from urea by immobilized urease.

  20. Resistive switching in a metal-insulator-metal device with γ-APTES as the insulator layer

    Science.gov (United States)

    Lin, Jing-Jenn; Lin, Shih-Hung; Wu, You-Lin

    2017-10-01

    Gamma-aminopropyltriethoxysilane (γ-APTES) is an organosilane material commonly used for biomedical sensing. Sensors with a γ-APTES surface layer have been reported for use in pH, DNA, and cell detection. However, no application of γ-APTES on resistive switching random access memory (RRAM) devices has yet been reported. In this paper, we report, for the first time, the resistive switching characteristics of using γ-APTES as the insulator layer in an RRAM device. The resistive switching of the γ-APTES layer embedded with ZnO nanoparticles is also investigated in this work. A unipolar resistive switching characteristic is found when the γ-APTES is employed as an insulator layer in a device with a metal-insulator-metal (MIM) structure. The stability and reliability of the resistive switching characteristics of the device can be improved after adding zinc oxide (ZnO) nanoparticles at the expense of reducing the ratio of the resistance of a high-resistance state (RHRS) to the resistance of a low-resistance state (RLRS).

  1. Design of Optical Metamaterial Mirror with Metallic Nanoparticles for Broadband Light Absorption in Graphene Optoelectronic Devices

    CERN Document Server

    Lee, Seungwoo

    2015-01-01

    A general metallic mirror (i.e., a flat metallic surface) has been a popular optical component that can contribute broadband light absorption to thin-film optoelectronic devices; nonetheless, such electric mirror with a reversal of reflection phase inevitably causes the problem of minimized electric field near at the mirror surface (maximized electric field at one quarter of wavelength from mirror). This problem becomes more elucidated, when the deep-subwavelength-scaled two-dimensional (2D) material (e.g., graphene and molybdenum disulfide) is implemented into optoelectronic device as an active channel layer. The purpose of this work was to conceive the idea for using a charge storage layer (spherical Au nanoparticles (AuNPs), embedded into dielectric matrix) of the floating-gate graphene photodetector as a magnetic mirror, which allows the device to harness the increase in broadband light absorption. In particular, we systematically examined whether the versatile assembly of spherical AuNP monolayer within ...

  2. Metal Nanoparticle-Decorated Two-Dimensional Molybdenum Sulfide for Plasmonic-Enhanced Polymer Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Ming-Kai Chuang

    2015-08-01

    Full Text Available Atomically thin two-dimensional (2D transition metal dichalcogenides have also attracted immense interest because they exhibit appealing electronic, optical and mechanical properties. In this work, we prepared gold nanoparticle-decorated molybdenum sulfide (AuNP@MoS2 through a simple spontaneous redox reaction. Transmission electron microscopy, UV-Vis spectroscopy, and Raman spectroscopy were used to characterize the properties of the AuNP@MoS2 nanomaterials. Then we employed such nanocomposites as the cathode buffer layers of organic photovoltaic devices (OPVs to trigger surface plasmonic resonance, leading to noticeable enhancements in overall device efficiencies. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the effects of localized surface plasmonic resonance. Our results suggest that the metal nanoparticle-decorated two-dimensional materials appear to have great potential for use in high-performance OPVs.

  3. COMPUTER CONTROLLED EXPERIMENTAL DEVICE FOR INVESTIGATIONS OF TRIBOLOGICAL INFLUENCES IN SHEET METAL FORMING

    Directory of Open Access Journals (Sweden)

    Tomislav Vujinović

    2012-05-01

    Full Text Available Sheet metal forming, especially deep drawing process is influenced by many factors. Blank holding force and drawbead displacement are two of them that can be controlled during the forming process.For this purpose, an electro-hydraulic computerized sheet-metal strip sliding device has been constructed. The basic characteristic of this device is realization of variable contact pressure and drawbead height as functions of time or stripe displacement. There are both, pressure and drawbead, ten linear and nonlinear functions. Additional features consist of the ability to measure drawing force, contact pressure, drawbead displacement etc.The device overview and first results of steel sheet stripe sliding over rounded drawbead are presented in the paper.

  4. Electrochemical sensors and devices for heavy metals assay in water: the French groups' contribution

    Directory of Open Access Journals (Sweden)

    Luca ePUJOL

    2014-04-01

    Full Text Available A great challenge in the area of heavy metal trace detection is the development of electrochemical techniques and devices which are user-friendly, robust, selective, with low detection limits and allowing fast analyses. This review presents the major contribution of the French scientific academic community in the field of electrochemical sensors and electroanalytical methods within the last 20 years. From the well-known polarography to the up-to-date generation of functionalized interfaces, the different strategies dedicated to analytical performances improvement are exposed: stripping voltammetry, solid mercury-free electrode, ion selective sensor, carbon based materials, chemically modified electrodes, nano-structured surfaces. The paper particularly emphasizes their advantages and limits face to the last Water Frame Directive devoted to the Environmental Quality Standards for heavy metals. Recent trends on trace metal speciation as well as on automatic on line monitoring devices are also evoked.

  5. Metal-Anion Pairing at Oxide/Water Interfaces: Theoretical and Experimental Investigations from the Nanoscale to the Macroscale

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Heather [The Ohio State Univ., Columbus, OH (United States)

    2016-11-14

    We combine the use of several techniques including bulk adsorption experiments, X-ray absorption, infrared, total internal reflection Raman, and vibrational sum frequencygeneration (XAS, IR, TIR-Raman, VSFG) spectroscopies, and molecular modeling to investigate ion adsorption at mineral surfaces. XAS and TIR-Raman provides data on how the metal binds to the surface (e.g., monodentate, bidentate), IR provides data on bulk anion adsorption at mineral surfaces from aqueous solutions, and VSFG provides surface specific data on anion adsorption at the mineral surface as well as impact of adsorbed metal-anion pairs on water structure at the mineral surface. Molecular modeling is used to guide spectroscopic data interpretation by providing information on water structure around ions in solution and the structure of metal-anion complexes in aqueous solutions. In addition, molecular modeling is used to provide insight into water structure at mineral surfaces, the surface sites involved in ion adsorption, and the distribution of ion pairs between aqueous solution and the mineral surface. Our studies have focused on systems involving alkaline earth metal (Mg2+, Ca2+, Sr2+, Ba2+) and heavy metal (Co2+, Cd2+) cations. The anions we have selected for studyinclude Cl-, NO3-, ClO4-, SO42-, SeO32-, and SeO42-. Ion adsorption and the potential formation ofternary complexes on silica (quartz, amorphous silica), alumina (corundum and gibbsite), and ferric iron oxides (goethite and hematite) are under investigation.

  6. Water as an agent for the morphology modification of metal oxalate materials on the nanoscale: from sheets to rods

    Science.gov (United States)

    Kim, Minog; Kim, Yoojin; Kwon, Wonjong; Yoon, Sungho

    2016-01-01

    A number of approaches have been used to control the shape of metal oxalates, which often used as precursors for metal oxide nanomaterials. However, attempts to use water as a regulator have not been reported. Here in we report systematic studies on related topics: nanosheets, composed of 1-dimensional [M(C2O4)(EG)] (M = Zn or Co) polymeric structure, could be transformed into nanorods by using water as a shape-shifting agent because water can readily substitute EG ligand, leading alternation of inter-chain hydrogen bonding interactions. In addition, heat-treatment of these nanomaterials with diverse morphologies resulted in porous metal oxides with high degrees of shape retention.

  7. Emerging ferroelectric transistors with nanoscale channel materials: the possibilities, the limitations

    Science.gov (United States)

    Hong, Xia

    2016-03-01

    Combining the nonvolatile, locally switchable polarization field of a ferroelectric thin film with a nanoscale electronic material in a field effect transistor structure offers the opportunity to examine and control a rich variety of mesoscopic phenomena and interface coupling. It is also possible to introduce new phases and functionalities into these hybrid systems through rational design. This paper reviews two rapidly progressing branches in the field of ferroelectric transistors, which employ two distinct classes of nanoscale electronic materials as the conducting channel, the two-dimensional (2D) electron gas graphene and the strongly correlated transition metal oxide thin films. The topics covered include the basic device physics, novel phenomena emerging in the hybrid systems, critical mechanisms that control the magnitude and stability of the field effect modulation and the mobility of the channel material, potential device applications, and the performance limitations of these devices due to the complex interface interactions and challenges in achieving controlled materials properties. Possible future directions for this field are also outlined, including local ferroelectric gate control via nanoscale domain patterning and incorporating other emergent materials in this device concept, such as the simple binary ferroelectrics, layered 2D transition metal dichalcogenides, and the 4d and 5d heavy metal compounds with strong spin-orbit coupling.

  8. Nanoscale Fluorescent Metal-Organic Framework@Microporous Organic Polymer Composites for Enhanced Intracellular Uptake and Bioimaging.

    Science.gov (United States)

    Wang, Lei; Wang, Weiqi; Zheng, Xiaohua; Li, Zhensheng; Xie, Zhigang

    2017-01-26

    Polymer-modified metal-organic frameworks combine the advantages of both soft polymers and crystalline metal-organic frameworks (MOFs). It is a big challenge to develop simple methods for surface modification of MOFs. In this work, MOF@microporous organic polymer (MOP) hybrid nanoparticles (UNP) have been synthesized by epitaxial growth of luminescent boron-dipyrromethene (BODIPYs)-imine MOPs on the surface of UiO-MOF seeds, which exhibit low cytotoxicity, smaller size distribution, well-retained pore integrity, and available functional sites. After folic acid grafting, the enhanced intracellular uptake and bioimaging was validated.

  9. Floating substrate luminescence from silicon rich oxide metal-oxide-semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Sánchez, A., E-mail: alfredo.morales@cimav.edu.mx [Centro de Investigación en Materiales Avanzados S. C., Unidad Monterrey-PIIT, 66600 Apodaca, Nuevo León (Mexico); Domínguez, C. [Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC). 08193 Barcelona (Spain); Barreto, J. [Nanoscale Physics Research Laboratory, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Aceves-Mijares, M. [INAOE, Electronics Department, Apartado 51, 72000 Puebla (Mexico); Licea-Jiménez, L. [Centro de Investigación en Materiales Avanzados S. C., Unidad Monterrey-PIIT, 66600 Apodaca, Nuevo León (Mexico); Luna-López, J.A.; Carrillo, J. [CIDS-ICUAP. Benemérita Universidad Autónoma de Puebla. 72570 Puebla (Mexico)

    2013-03-01

    The electro-optical properties of metal-oxide-semiconductor devices with embedded Si nanoparticles in silicon-rich (4 at.%) oxide films have been studied. Devices show intense visible continuous luminescence not only in the regular metal-oxide-semiconductor configuration, but when biased via surface electrodes (floating substrate) separated 10 μm. Electroluminescence manifests as extremely bright randomly scattered discrete spots on the gate area or the periphery of the devices depending on the bias direction. The mechanism responsible for the surface-electroluminescence has been related to the recombination of electron–hole pairs injected through enhanced current paths within the silicon-rich oxide film. - Highlights: ► Silicon rich oxide (SRO) based metal-oxide-semiconductor like luminescent devices. ► Electroluminescence (EL) in floating-substrate, horizontal electrodes configuration. ► EL is observed as multiple shining spots with surface electrodes. ► Preferential current paths established in the SRO between several electrodes.

  10. Flexible semi-transparent silicon (100) fabric with high-k/metal gate devices

    KAUST Repository

    Rojas, Jhonathan Prieto

    2013-01-07

    Can we build a flexible and transparent truly high performance computer? High-k/metal gate stack based metal-oxide-semiconductor capacitor devices are monolithically fabricated on industry\\'s most widely used low-cost bulk single-crystalline silicon (100) wafers and then released as continuous, mechanically flexible, optically semi-transparent and high thermal budget compatible silicon fabric with devices. This is the first ever demonstration with this set of materials which allows full degree of freedom to fabricate nanoelectronics devices using state-of-the-art CMOS compatible processes and then to utilize them in an unprecedented way for wide deployment over nearly any kind of shape and architecture surfaces. Electrical characterization shows uncompromising performance of post release devices. Mechanical characterization shows extra-ordinary flexibility (minimum bending radius of 1 cm) making this generic process attractive to extend the horizon of flexible electronics for truly high performance computers. Schematic and photograph of flexible high-k/metal gate MOSCAPs showing high flexibility and C-V plot showing uncompromised performance. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Impact of scaling on the performance and reliability degradation of metal-contacts in NEMS devices

    KAUST Repository

    Dadgour, Hamed F.

    2011-04-01

    Nano-electro-mechanical switches (NEMS) offer new possibilities for the design of ultra energy-efficient systems; however, thus far, all the fabricated NEMS devices require high supply voltages that limit their applicability for logic designs. Therefore, research is being conducted to lower the operating voltages by scaling down the physical dimensions of these devices. However, the impact of device scaling on the electrical and mechanical properties of metal contacts in NEMS devices has not been thoroughly investigated in the literature. Such a study is essential because metal contacts play a critical role in determining the overall performance and reliability of NEMS. Therefore, the comprehensive analytical study presented in this paper highlights the performance and reliability degradations of such metal contacts caused by scaling. The proposed modeling environment accurately takes into account the impact of roughness of contact surfaces, elastic/plastic deformation of contacting asperities, and various inter-molecular forces between mating surfaces (such as Van der Waals and capillary forces). The modeling results are validated and calibrated using available measurement data. This scaling analysis indicates that the key contact properties of gold contacts (resistance, stiction and wear-out) deteriorate "exponentially" with scaling. Simulation results demonstrate that reliable (stiction-free) operation of very small contact areas (≈ 6nm x 6nm) will be a daunting task due to the existence of strong surface forces. Hence, contact degradation is identified as a major problem to the scaling of NEMS transistors. © 2011 IEEE.

  12. Potential resource and toxicity impacts from metals in waste electronic devices.

    Science.gov (United States)

    Woo, Seung H; Lee, Dae Sung; Lim, Seong-Rin

    2016-04-01

    As a result of the continuous release of new electronic devices, existing electronic devices are quickly made obsolete and rapidly become electronic waste (e-waste). Because e-waste contains a variety of metals, information about those metals with the potential for substantial environmental impact should be provided to manufacturers, recyclers, and disposers to proactively reduce this impact. This study assesses the resource and toxicity (i.e., cancer, noncancer, and ecotoxicity) potentials of various heavy metals commonly found in e-waste from laptop computers, liquid-crystal display (LCD) monitors, LCD TVs, plasma TVs, color cathode ray tube (CRT) TVs, and cell phones and then evaluates such potentials using life cycle impact-based methods. Resource potentials derive primarily from Cu, Sb, Ag, and Pb. Toxicity potentials derive primarily from Pb, Ni, and Hg for cancer toxicity; from Pb, Hg, Zn, and As for noncancer toxicity; and from Cu, Pb, Hg, and Zn for ecotoxicity. Therefore, managing these heavy metals should be a high priority in the design, recycling, and disposal stages of electronic devices.

  13. A device for maintenance of large diameter metal seat plug valve; Dispositivo para manutencao de valvula macho de grande diametro com sede metal-metal

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Osmar Jose Leite da [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2003-07-01

    The present work is a PETROBRAS S.A. patent request, which presents an alternative for national technology in the metal seat Plug Valve maintenance area, widely used in Petrochemical plants. Before this device, the only alternative for national companies to accomplish a reliable maintenance was to ship of the valves to their makers abroad. However, the high cost and long shipping time made this kind of maintenance unfeasible. These factors led to the beginning of the research resulting in the device described here. The device assures the valves' seat-sealing reliability. This device has been successfully used by two national Refineries : 'Presidente Bernardes' Refinery and 'Planalto Paulista' Refinery. (author)

  14. A transparent electrochromic metal-insulator switching device with three-terminal transistor geometry

    Science.gov (United States)

    Katase, Takayoshi; Onozato, Takaki; Hirono, Misako; Mizuno, Taku; Ohta, Hiromichi

    2016-05-01

    Proton and hydroxyl ion play an essential role for tuning functionality of oxides because their electronic state can be controlled by modifying oxygen off-stoichiometry and/or protonation. Tungsten trioxide (WO3), a well-known electrochromic (EC) material for smart window, is a wide bandgap insulator, whereas it becomes a metallic conductor HxWO3 by protonation. Although one can utilize electrochromism together with metal-insulator (MI) switching for one device, such EC-MI switching cannot be utilized in current EC devices because of their two-terminal structure with parallel-plate configuration. Here we demonstrate a transparent EC-MI switchable device with three-terminal TFT-type structure using amorphous (a-) WO3 channel layer, which was fabricated on glass substrate at room temperature. We used water-infiltrated nano-porous glass, CAN (calcium aluminate with nano-pores), as a liquid-leakage-free solid gate insulator. At virgin state, the device was fully transparent in the visible-light region. For positive gate voltage, the active channel became dark blue, and electrical resistivity of the a-WO3 layer drastically decreased with protonation. For negative gate voltage, deprotonation occurred and the active channel returned to transparent insulator. Good cycleability of the present transparent EC-MI switching device would have potential for the development of advanced smart windows.

  15. Metal oxide resistive random access memory based synaptic devices for brain-inspired computing

    Science.gov (United States)

    Gao, Bin; Kang, Jinfeng; Zhou, Zheng; Chen, Zhe; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan

    2016-04-01

    The traditional Boolean computing paradigm based on the von Neumann architecture is facing great challenges for future information technology applications such as big data, the Internet of Things (IoT), and wearable devices, due to the limited processing capability issues such as binary data storage and computing, non-parallel data processing, and the buses requirement between memory units and logic units. The brain-inspired neuromorphic computing paradigm is believed to be one of the promising solutions for realizing more complex functions with a lower cost. To perform such brain-inspired computing with a low cost and low power consumption, novel devices for use as electronic synapses are needed. Metal oxide resistive random access memory (ReRAM) devices have emerged as the leading candidate for electronic synapses. This paper comprehensively addresses the recent work on the design and optimization of metal oxide ReRAM-based synaptic devices. A performance enhancement methodology and optimized operation scheme to achieve analog resistive switching and low-energy training behavior are provided. A three-dimensional vertical synapse network architecture is proposed for high-density integration and low-cost fabrication. The impacts of the ReRAM synaptic device features on the performances of neuromorphic systems are also discussed on the basis of a constructed neuromorphic visual system with a pattern recognition function. Possible solutions to achieve the high recognition accuracy and efficiency of neuromorphic systems are presented.

  16. Using NV centers to probe magnetization dynamics in normal metal/magnetic insulator hybrid system at the nanoscale

    Science.gov (United States)

    Zhang, Huiliang; Ku, Mark J. H.; Han, Minyong; Casola, Francesco; van der Sar, Toeno; Yacoby, Amir; Walsworth, Ronald L.

    2016-05-01

    Understanding magnetization dynamics induced by electric current is of great interest for both fundamental and practical reasons. Great endeavor has been dedicated to spin-orbit torques (SOT) in metallic structures, while quantitative study of analogous phenomena in magnetic insulators remains challenging where transport measurements are not feasible. Recently we have developed techniques using nitrogen vacancy (NV) centers in diamond to probe few-nanometre-scale correlated-electron magnetic excitations (i.e., spin waves). Here we demonstrate how this powerful tool can be implemented to study magnetization dynamics inside ferromagnetic insulator, Yttrium iron garnet (YIG) with spin injection from electrical current through normal metal (Platinum in our case). Particularly our work will focus on NV magnetic detection, imaging, and spectroscopy of coherent auto-oscillations in Pt/YIG microdisc. Magnetic fluctuations and local temperature measurements, both with nearby NV centers, will also be interesting topics relevant to SOT physics in Pt/YIG hybrid system.

  17. Sensing at the nanoscale

    Science.gov (United States)

    Demming, Anna; Hierold, Christofer

    2013-11-01

    The merits of nanostructures in sensing may seem obvious, yet playing these attributes to their maximum advantage can be a work of genius. As fast as sensing technology is improving, expectations are growing, with demands for cheaper devices with higher sensitivities and an ever increasing range of functionalities and compatibilities. At the same time tough scientific challenges like low power operation, noise and low selectivity are keeping researchers busy. This special issue on sensing at the nanoscale with guest editor Christofer Hierold from ETH Zurich features some of the latest developments in sensing research pushing at the limits of current capabilities. Cheap and easy fabrication is a top priority. Among the most popular nanomaterials in sensing are ZnO nanowires and in this issue Dario Zappa and colleagues at Brescia University in Italy simplify an already cheap and efficient synthesis method, demonstrating ZnO nanowire fabrication directly onto silicon substrates [1]. Meanwhile Nicolae Barson and colleagues in Germany point out the advantages of flame spray pyrolysis fabrication in a topical review [2] and, maximizing on existing resources, researchers in Denmark and Taiwan report cantilever sensing using a US20 commercial DVD-ROM optical pickup unit as the readout source [3]. The sensor is designed to detect physiological concentrations of soluble urokinase plasminogen activator receptor, a protein associated with inflammation due to HIV, cancer and other infectious diseases. With their extreme properties carbon nanostructures feature prominently in the issue, including the demonstration of a versatile and flexible carbon nanotube strain sensor [4] and a graphene charge sensor with sensitivities of the order of 1.3 × 10-3 e Hz-1/2 [5]. The issue of patterning for sensing devices is also tackled by researchers in the US who demonstrate a novel approach for multicomponent pattering metal/metal oxide nanoparticles on graphene [6]. Changes in electrical

  18. Chitosan capped nanoscale Fe-MIL-88B-NH2 metal-organic framework as drug carrier material for the pH responsive delivery of doxorubicin

    Science.gov (United States)

    Sivakumar, P.; Priyatharshni, S.; Nagashanmugam, K. B.; Thanigaivelan, A.; Kumar, K.

    2017-08-01

    In recent years nanoscale metal-organic frameworks (NMOFs) are contributing as an effective material for use in drug delivery and imaging applications due to their porous surfaces and easy surface modifications. In this work, Fe-MIL-88B-NH2 NMOFs were successfully synthesized on facile hydrothermal route and 2-aminoterephthalic acid (NH2-BDC) was employed as a bridging ligand to activate amine functional groups on the surface. Amine functional groups not only serve as a structure stabilizing agent but also enhance the loading efficiency of the doxorubicin (DOX) anticancer drug. A pH responsive DOX release was realized by introducing a positively charged chitosan (Chi) capping layer. Upon Chi-coating, cleavage was observed in the Fe-MIL-88B-NH2 structure at acidic pH, while gel-like insoluble structure was formed at basic pH. By utilizing this phenomenon, a pH responsive DOX release system was developed by using Chi capped Fe-MIL-88B-NH2 NMOFs under the designed pH (4.0-8.0). The results suggest the Chi capped Fe-MIL-88B-NH2 can be a promising candidate for future pH responsive drug delivery systems.

  19. Nanoscale zero-valent iron particles supported on reduced graphene oxides by using a plasma technique and their application for removal of heavy-metal ions.

    Science.gov (United States)

    Li, Jie; Chen, Changlun; Zhang, Rui; Wang, Xiangke

    2015-06-01

    Nanoscale zero-valent iron particles supported on reduced graphene oxides (NZVI/rGOs) from spent graphene oxide (GO)-bound iron ions were developed by using a hydrogen/argon plasma reduction method to improve the reactivity and stability of NZVI. The NZVI/rGOs exhibited excellent water treatment performance with excellent removal capacities of 187.16 and 396.37 mg g(-1) for chromium and lead, respectively. Moreover, the NZVI/rGOs could be regenerated by plasma treatment and maintained high removal ability after four cycles. X-ray photoelectron spectroscopy analysis results implied that the removal mechanisms could be attributed to adsorption/precipitation, reduction, or both. Such multiple removal mechanisms by the NZVI/rGOs were attributed to the reduction ability of the NZVI particles and the role of dispersing and stabilizing abilities of the rGOs. The results indicated that the NZVI/rGOs prepared by a hydrogen/argon plasma reduction method might be an effective composite for heavy-metal-ion removal.

  20. Nanoscale control of the LaAlO3/SrTiO3 metal-insulator transition using a self-assembled monolayer of APTES

    Science.gov (United States)

    Li, Jianan; Huang, Mengcheng; Irvin, Patrick; Levy, Jeremy; Ryu, Sangwoo; Eom, Chang-Beom; Eichelsdoerfer, Daniel; Brown, Keith; Mirkin, Chad

    2014-03-01

    Nanoscale control over the metal-insulator transition at oxide interfaces represents an exciting opportunity for science and technology. Nanostructures created from 3-unit-cell LaAlO3/SrTiO3 heterostructures via a conductive AFM technique typically decay within hours under ambient conditions, representing a challenge for some technologies. By chemically modifying the top LaAlO3 surface with a self-assembled monolayer of (3-Aminopropyl)triethoxysilane (APTES), normally conductive 4-unit-cell LaAlO3/SrTiO3 can be made highly insulating. The APTES layer can be locally patterned, revealing a highly stable conductive nanoregion. Four-terminal measurements show that nanowires created by selective desorption of APTES remain conductive indefinitely under ambient conditions. The results suggest a robust mechanism for creating long-lived nanostructures at oxide interfaces. We gratefully acknowledge support from NSF (DMR-1124131) and AFOSR (FA9550-12-1-0268, FA9550-10-1-0524, FA9550-12-1-0342).

  1. One-pot synthesis of multifunctional nanoscale metal-organic frameworks as an effective antibacterial agent against multidrug-resistant Staphylococcus aureus

    Science.gov (United States)

    Chowdhuri, Angshuman Ray; Das, Balaram; Kumar, Amit; Tripathy, Satyajit; Roy, Somenath; Sahu, Sumanta Kumar

    2017-03-01

    Drug-resistant bacteria are an increasingly serious threat to global public health. In particular, infections from multidrug-resistant (MDR) Gram-positive bacteria (i.e. Staphylococcus aureus) are growing global health concerns. In this work, we report the first use of nanoscale metal-organic frameworks (NMOFs) coencapsulating an antibiotic (vancomycin) and targeting ligand (folic acid) in one pot to enhance therapeutic efficacy against MDR S. aureus. Zeolitic imidazolate framework (ZIF-8) NMOFs, which have globular morphologies coencapsulating vancomycin and folic acid, are characterized by transmission electron microscopy, field-emission scanning electron microscopy, powder x-ray diffraction, ulltraviolet–visible spectroscopy, and dynamic light-scattering techniques. We determined that the presence of folic acid on the surface of the NMOFs is significant in the sense of effective uptake by MDR S. aureus through endocytosis. The functionalized NMOFs transport vancomycin across the cell wall of MDR S. aureus and enhance antibacterial activity, which has been confirmed from studies of the minimum inhibitory concentration, minimum bactericidal concentration, cytotoxicity of bacterial cells, and generation of reactive oxygen species. This work shows that functionalized NMOFs hold great promise for effective treatment of MDR S. aureus.

  2. Direct observation of nanoscale Peltier and Joule effects at metal-insulator domain walls in vanadium dioxide nanobeams.

    Science.gov (United States)

    Favaloro, Tela; Suh, Joonki; Vermeersch, Bjorn; Liu, Kai; Gu, Yijia; Chen, Long-Qing; Wang, Kevin X; Wu, Junqiao; Shakouri, Ali

    2014-05-14

    The metal to insulator transition (MIT) of strongly correlated materials is subject to strong lattice coupling, which brings about the unique one-dimensional alignment of metal-insulator (M-I) domains along nanowires or nanobeams. Many studies have investigated the effects of stress on the MIT and hence the phase boundary, but few have directly examined the temperature profile across the metal-insulating interface. Here, we use thermoreflectance microscopy to create two-dimensional temperature maps of single-crystalline VO2 nanobeams under external bias in the phase coexisting regime. We directly observe highly localized alternating Peltier heating and cooling as well as Joule heating concentrated at the M-I domain boundaries, indicating the significance of the domain walls and band offsets. Utilizing the thermoreflectance technique, we are able to elucidate strain accumulation along the nanobeam and distinguish between two insulating phases of VO2 through detection of the opposite polarity of their respective thermoreflectance coefficients. Microelasticity theory was employed to predict favorable domain wall configurations, confirming the monoclinic phase identification.

  3. Transition Metal Dithiolene Near-IR Dyes and Thier Applications in Liquid Crystal Devices

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, K.L.; Painter, G.; Lotito, K.; Noto, A.G.; Chang, P.

    2006-08-18

    Numerous commercial and military applications exist for guest–host liquid crystal (LC) devices operating in the near- to mid-IR region. Progress in this area has been hindered by the severe lack of near-IR dyes with good solubility in the LC host, low impact on the inherent order of the LC phase, good thermal and chemical stability, and a large absorbance maximum tunable by structural modification over a broad range of the near-IR region. Transition metal complexes based on nickel, palladium, or platinum dithiolene cores show substantial promise in meeting these requirements. In this paper, we overview our past and present activities in the design and synthesis of transition metal dithiolene dyes, show some specific applications examples for these materials as near-IR dyes in LC electro-optical devices, and present our most recent results in the computational modeling of physical and optical properties of this interesting class of organometallic optical materials.

  4. Solid State Dye Solar Cells with Metallic Regenerators towards devices with enhanced active area

    Energy Technology Data Exchange (ETDEWEB)

    Lenzmann, F.O.; Olson, C.; Pichon, P.Y.; Heurtault, B.; Goris, M.J.A.A.; Budel, T. [ECN Solar Energy, Westerduinweg 3, NL-1755 LE Petten (Netherlands)

    2007-08-15

    In an alternative approach to solid state dye solar cells a molecular dye is situated at the interface between a TiO2 film and a metallic (Au) film. In a proof of principle with flat model devices, we have shown earlier that the Au layer efficiently regenerates the charge-neutral state of the dye upon electron injection into the TiO2 conduction band under illumination. For practically more relevant devices an increased active area is required for enhanced current output. A specially adapted TiO2 morphology with nanotubular morphology can minimize reflection losses from the metallic regenerator. In this paper the preparation of such films on transparent SnO2:F-coated glass substrates by electrochemical anodization of titanium layers is described. The focus is on preparative parameters with direct influence on film properties relevant to the application in solid-state dye solar cells (transparency and mechanical integrity of the layers)

  5. Gate stack and channel engineering: Study of metal gates and germanium channel devices

    Science.gov (United States)

    Todi, Ravi M.

    The continued scaling of device dimensions in complementary metal oxide semiconductor (CMOS) technology within the sub-100 nm region requires an alternative high dielectric constant (high-kappa) oxide layer to counter high tunneling leakage currents, a metallic gate electrode to address polysilicon depletion, boron penetration and high polysilicon sheet resistance, and high mobility channel materials to boost the CMOS performance. Metal gates can also offer improved thermal and chemical stability, but their use requires that we improve our understanding of how the metal alloy phase, crystallographic orientation, and composition affect the electronic properties of the metal alloy-oxide interface. To replace n++ and p++ polysilicon gate electrodes and maintain scaled device performance requires metal gate electrodes with work functions within 0.2 eV of the silicon conduction and valence band edges, i.e., 5.0-5.2 and 4.1-4.3 eV, for PMOS and NMOS devices, respectively. In addition to work function and thermal/chemical stability, metal gates must be integrated into the CMOS process flow. It is the aim of this work to significantly expand our knowledge base in alloys for dual metal gates by carrying out detailed electrical and materials studies of the binary alloy systems of Ru with p-type metal Pt. Three n-type metals systems, Ru-Ta, Ru-Hf and Ru-Nb have also been partially investigated. This work also focuses on high mobility Ge p-MOSFETs for improved CMOS performance. DC magnetron sputtering has been used to deposit binary alloy films on thermally grown SiO2. The composition of the alloy films have been determined by Rutherford backscattering spectrometry and the identification of phases present have been made using x-ray and electron diffraction of samples. The microstructure of the phases of interest has been examined in the transmission electron microscope and film texture was characterized via x-ray diffraction. The electrical characterization includes basic

  6. Implanted cardiac devices are reliably detected by commercially available metal detectors

    DEFF Research Database (Denmark)

    Holm, Katja Fiedler; Hjortshøj, Søren; Pehrson, Steen;

    2013-01-01

    Explosions of Cardiovascular Implantable Electronic Devices (CIEDs) (pacemakers, defibrillators, and loop recorders) are a well-recognized problem during cremation, due to lithium-iodine batteries. In addition, burial of the deceased with a CIED can present a potential risk for environmental cont...... contamination. Therefore, detection of CIEDs in the deceased would be of value. This study evaluated a commercially available metal detector for detecting CIEDs....

  7. Formation of x-ray Newton’s rings from nano-scale spallation shells of metals in laser ablation

    Directory of Open Access Journals (Sweden)

    Masaharu Nishikino

    2017-01-01

    Full Text Available The initial stages of the femtosecond (fs laser ablation process of gold, platinum, and tungsten were observed by single-shot soft x-ray imaging technique. The formation and evolution of soft x-ray Newton’s rings (NRs were found for the first time. The soft x-ray NRs are caused by the interference between the bulk ablated surface and nanometer-scale thin spallation layer; they originate from the metal surface at pump energy fluence of around 1 J/cm2 and work as a flying soft x-ray beam splitter.

  8. Formation of x-ray Newton's rings from nano-scale spallation shells of metals in laser ablation

    Science.gov (United States)

    Nishikino, Masaharu; Hasegawa, Noboru; Tomita, Takuro; Minami, Yasuo; Eyama, Takashi; Kakimoto, Naoya; Izutsu, Rui; Baba, Motoyoshi; Kawachi, Tetsuya; Suemoto, Tohru

    2017-01-01

    The initial stages of the femtosecond (fs) laser ablation process of gold, platinum, and tungsten were observed by single-shot soft x-ray imaging technique. The formation and evolution of soft x-ray Newton's rings (NRs) were found for the first time. The soft x-ray NRs are caused by the interference between the bulk ablated surface and nanometer-scale thin spallation layer; they originate from the metal surface at pump energy fluence of around 1 J/cm2 and work as a flying soft x-ray beam splitter.

  9. Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane

    OpenAIRE

    Wahiduzzaman,; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

    2017-01-01

    We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30–200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000–5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanopartic...

  10. Long Channel Carbon Nanotube as an Alternative to Nanoscale Silicon Channels in Scaled MOSFETs

    Directory of Open Access Journals (Sweden)

    Michael Loong Peng Tan

    2013-01-01

    Full Text Available Long channel carbon nanotube transistor (CNT can be used to overcome the high electric field effects in nanoscale length silicon channel. When maximum electric field is reduced, the gate of a field-effect transistor (FET is able to gain control of the channel at varying drain bias. The device performance of a zigzag CNTFET with the same unit area as a nanoscale silicon metal-oxide semiconductor field-effect transistor (MOSFET channel is assessed qualitatively. The drain characteristic of CNTFET and MOSFET device models as well as fabricated CNTFET device are explored over a wide range of drain and gate biases. The results obtained show that long channel nanotubes can significantly reduce the drain-induced barrier lowering (DIBL effects in silicon MOSFET while sustaining the same unit area at higher current density.

  11. Patch Testing for Evaluation of Hypersensitivity to Implanted Metal Devices: A Perspective From the American Contact Dermatitis Society.

    Science.gov (United States)

    Schalock, Peter C; Crawford, Glen; Nedorost, Susan; Scheinman, Pamela L; Atwater, Amber Reck; Mowad, Christen; Brod, Bruce; Ehrlich, Alison; Watsky, Kalman L; Sasseville, Denis; Silvestri, Dianne; Worobec, Sophie M; Elliott, John F; Honari, Golara; Powell, Douglas L; Taylor, James; DeKoven, Joel

    2016-01-01

    The American Contact Dermatitis Society recognizes the interest in the evaluation and management of metal hypersensitivity reactions. Given the paucity of robust evidence with which to guide our practices, we provide reasonable evidence and expert opinion-based guidelines for clinicians with regard to metal hypersensitivity reaction testing and patient management. Routine preoperative evaluation in individuals with no history of adverse cutaneous reactions to metals or history of previous implant-related adverse events is not necessary. Patients with a clear self-reported history of metal reactions should be evaluated by patch testing before device implant. Patch testing is only 1 element in the assessment of causation in those with postimplantation morbidity. Metal exposure from the implanted device can cause sensitization, but a positive metal test does not prove symptom causality. The decision to replace an implanted device must include an assessment of all clinical factors and a thorough risk-benefit analysis by the treating physician(s) and patient.

  12. Heat transfer across the interface between nanoscale solids and gas.

    Science.gov (United States)

    Cheng, Chun; Fan, Wen; Cao, Jinbo; Ryu, Sang-Gil; Ji, Jie; Grigoropoulos, Costas P; Wu, Junqiao

    2011-12-27

    When solid materials and devices scale down in size, heat transfer from the active region to the gas environment becomes increasingly significant. We show that the heat transfer coefficient across the solid-gas interface behaves very differently when the size of the solid is reduced to the nanoscale, such as that of a single nanowire. Unlike for macroscopic solids, the coefficient is strongly pressure dependent above ∼10 Torr, and at lower pressures it is much higher than predictions of the kinetic gas theory. The heat transfer coefficient was measured between a single, free-standing VO(2) nanowire and surrounding air using laser thermography, where the temperature distribution along the VO(2) nanowire was determined by imaging its domain structure of metal-insulator phase transition. The one-dimensional domain structure along the nanowire results from the balance between heat generation by the focused laser and heat dissipation to the substrate as well as to the surrounding gas, and thus serves as a nanoscale power-meter and thermometer. We quantified the heat loss rate across the nanowire-air interface, and found that it dominates over all other heat dissipation channels for small-diameter nanowires near ambient pressure. As the heat transfer across the solid-gas interface is nearly independent of the chemical identity of the solid, the results reveal a general scaling relationship for gaseous heat dissipation from nanostructures of all solid materials, which is applicable to nanoscale electronic and thermal devices exposed to gaseous environments.

  13. Transition metal oxides for organic electronics: energetics, device physics and applications.

    Science.gov (United States)

    Meyer, Jens; Hamwi, Sami; Kröger, Michael; Kowalsky, Wolfgang; Riedl, Thomas; Kahn, Antoine

    2012-10-23

    During the last few years, transition metal oxides (TMO) such as molybdenum tri-oxide (MoO(3) ), vanadium pent-oxide (V(2) O(5) ) or tungsten tri-oxide (WO(3) ) have been extensively studied because of their exceptional electronic properties for charge injection and extraction in organic electronic devices. These unique properties have led to the performance enhancement of several types of devices and to a variety of novel applications. TMOs have been used to realize efficient and long-term stable p-type doping of wide band gap organic materials, charge-generation junctions for stacked organic light emitting diodes (OLED), sputtering buffer layers for semi-transparent devices, and organic photovoltaic (OPV) cells with improved charge extraction, enhanced power conversion efficiency and substantially improved long term stability. Energetics in general play a key role in advancing device structure and performance in organic electronics; however, the literature provides a very inconsistent picture of the electronic structure of TMOs and the resulting interpretation of their role as functional constituents in organic electronics. With this review we intend to clarify some of the existing misconceptions. An overview of TMO-based device architectures ranging from transparent OLEDs to tandem OPV cells is also given. Various TMO film deposition methods are reviewed, addressing vacuum evaporation and recent approaches for solution-based processing. The specific properties of the resulting materials and their role as functional layers in organic devices are discussed.

  14. High Seebeck effects from conducting polymer: Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) based thin-film device with hybrid metal/polymer/metal architecture

    Energy Technology Data Exchange (ETDEWEB)

    Stanford, Michael G [ORNL; Wang, Hsin [ORNL; Ivanov, Ilia N [ORNL; Hu, Bin [University of Tennessee, Knoxville (UTK)

    2012-01-01

    Conductive polymers are of particular interest for thermoelectric applications due to their low thermal conductivity and relatively high electrical conductivity. In this study, commercially available conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used in a hybrid metal/polymer/metal thin film design in order to achieve a high Seebeck coefficient with the value of 252lV/k on a relatively low temperature scale. Polymer film thickness was varied in order to investigate its influence on the Seebeck effect. The high Seebeck coefficient indicates that the metal/polymer/metal design can develop a large entropy difference in internal energy of charge carriers between high and low-temperature metal electrodes to develop electrical potential due to charge transport in conducting polymer film through metal/polymer interface. Therefore, the metal/polymer/metal structure presents a new design to combine inorganic metals and organic polymers in thin-film form to develop Seebeck devices

  15. Recent advances in porous nanoparticles for drug delivery in antitumoral applications: inorganic nanoparticles and nanoscale metal-organic frameworks.

    Science.gov (United States)

    Baeza, Alejandro; Ruiz-Molina, Daniel; Vallet-Regí, María

    2017-06-01

    Nanotechnology has provided new tools for addressing unmet clinical situations, especially in the oncology field. The development of smart nanocarriers able to deliver chemotherapeutic agents specifically to the diseased cells and to release them in a controlled way has offered a paramount advantage over conventional therapy. Areas covered: Among the different types of nanoparticle that can be employed for this purpose, inorganic porous materials have received significant attention in the last decade due to their unique properties such as high loading capacity, chemical and physical robustness, low toxicity and easy and cheap production in the laboratory. This review discuss the recent advances performed in the application of porous inorganic and metal-organic materials for antitumoral therapy, paying special attention to the application of mesoporous silica, porous silicon and metal-organic nanoparticles. Expert opinion: The use of porous inorganic nanoparticles as drug carriers for cancer therapy has the potential to improve the life expectancy of the patients affected by this disease. However, much work is needed to overcome their drawbacks, which are aggravated by their hard nature, exploiting the advantages offered by highly the ordered pore network of these materials.

  16. Carbon Nanofibers Functionalized with Active Screen Plasma-Deposited Metal Nanoparticles for Electrical Energy Storage Devices.

    Science.gov (United States)

    Corujeira Gallo, Santiago; Li, Xiaoying; Fütterer, Klaus; Charitidis, Constantinos A; Dong, Hanshan

    2017-07-12

    Supercapacitors are energy storage devices with higher energy densities than conventional capacitors but lower than batteries or fuel cells. There is a strong interest in increasing the volumetric and gravimetric capacitance of these devices to meet the growing demands of the electrical and electronic sectors. The capacitance depends largely on the electrode material, and carbon nanofibers (CNFs) have attracted much attention because of their relatively low cost, large surface area, and good electrical conductivity as well as chemical and thermal stability. The deposition of metal nanoparticles on CNFs is a promising way to increase their surface properties and, ultimately, the capacitance of the devices. In this study, nickel and silver nanoparticles were deposited on CNFs using the active screen plasma technology. The CNFs were characterized, and their electrochemical performance was assessed in a three-electrode cell. The results show significant improvements over the untreated CNFs, particularly after functionalization with silver nanoparticles.

  17. Experimental Research of Electronic Devices Thermal Control Using Metallic Phase Change Materials

    Institute of Scientific and Technical Information of China (English)

    Ai-Gang Pan; Jun-Biao Wang; Xian-Jie Zhang; Xiao-Bao Cao

    2014-01-01

    A Phase-change thermal control unit ( PTCU) filled with metallic phase change material ( PCM) Bismuth alloy for electric devices thermal protection was developed and investigated experimentally. The PTCU filled with PCM was designed and manufactured. Resistance heating components ( RCHs) produced 1 W, 3 W, 5 W, 7W, and 10 W for simulating heat generation of electronic devices. At various heating power levels, the performance of PTCU were tested during heating period and one duty cycle period. The experimental results show that the PTCU delays RCH reaching the maximum operating temperature. Also, a numerical model was developed to enable interpretation of experimental results and to perform parametric studies. The results confirmed that the PTCU is suitable for electric devices thermal control.

  18. Multifunctional silicon-based light emitting device in standard complementary metal-oxide-semiconductor technology

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Huang Bei-Ju; Dong Zan; Chen Hong-Da

    2011-01-01

    A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes: it can emit visible to near infra-red (NIR) light (the spectrum ranges from 500 nm to 1000 nm) in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light (the spectrum ranges from 900 nm to 1300 nm) in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.

  19. Nanostructured metal chalcogenides: synthesis, modification, and applications in energy conversion and storage devices.

    Science.gov (United States)

    Gao, Min-Rui; Xu, Yun-Fei; Jiang, Jun; Yu, Shu-Hong

    2013-04-07

    Advanced energy conversion and storage (ECS) devices (including fuel cells, photoelectrochemical water splitting cells, solar cells, Li-ion batteries and supercapacitors) are expected to play a major role in the development of sustainable technologies that alleviate the energy and environmental challenges we are currently facing. The successful utilization of ECS devices depends critically on synthesizing new nanomaterials with merits of low cost, high efficiency, and outstanding properties. Recent progress has demonstrated that nanostructured metal chalcogenides (MCs) are very promising candidates for efficient ECS systems based on their unique physical and chemical properties, such as conductivity, mechanical and thermal stability and cyclability. In this review, we aim to provide a summary on the liquid-phase synthesis, modifications, and energy-related applications of nanostructured metal chalcogenide (MC) materials. The liquid-phase syntheses of various MC nanomaterials are primarily categorized with the preparation method (mainly 15 kinds of methods). To obtain optimized, enhanced or even new properties, the nanostructured MC materials can be modified by other functional nanomaterials such as carbon-based materials, noble metals, metal oxides, or MCs themselves. Thus, this review will then be focused on the recent strategies used to realize the modifications of MC nanomaterials. After that, the ECS applications of the MC/modified-MC nanomaterials have been systematically summarized based on a great number of successful cases. Moreover, remarks on the challenges and perspectives for future MC research are proposed (403 references).

  20. Orthopaedic metal devices coated with a novel antiseptic dye for the prevention of bacterial infections.

    Science.gov (United States)

    Bahna, Paul; Dvorak, Tanya; Hanna, Hend; Yasko, Alan W; Hachem, Ray; Raad, Issam

    2007-05-01

    Gendine is a novel antiseptic dye with broad-spectrum antimicrobial activity that may be used to coat plastics and metal devices. Our objective was to determine the efficacy of gendine-coated orthopaedic metal devices in preventing methicillin-resistant Staphylococcus aureus (MRSA) colonisation. Stainless steel and titanium Schanz rods were coated with gendine. The zone of inhibition (ZoI) around the rods with and without gamma-irradiation was determined by a modified Kirby-Bauer method. A previously published bioprosthetic biofilm colonisation model, modified Kuhn's method, was used to determine the adherence of MRSA to coated and uncoated rods, with and without irradiation, after insertion into bovine bone and after 3 months shelf life followed by 2 weeks of immersion in serum. The gendine-coated Schanz metal rods showed a net ZoI of 16 mm against MRSA before and after irradiation. Gendine-coated rods showed no biofilm formation (0 colony-forming units (CFU)), which was a significant reduction (P5000 CFU). Coated rods exposed to high-dose gamma-irradiation and coated rods drilled into bone also showed significant efficacy (P<0.001) in preventing biofilm adherence. After 2 weeks, gendine-coated rods maintained significant durability (P<0.01), resulting in 90% reduction in MRSA biofilm adherence compared with uncoated control rods. Results indicate that gendine-coated metal rods are highly efficacious in the prevention of MRSA biofilm.

  1. Charge transport in nanoscale junctions.

    Science.gov (United States)

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-03

    Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at

  2. Personal exposure assessment to particulate metals using a paper-based analytical device

    Science.gov (United States)

    Cate, David; Volckens, John; Henry, Charles

    2013-03-01

    The development of a paper-based analytical device (PAD) for assessing personal exposure to particulate metals will be presented. Human exposure to metal aerosols, such as those that occur in the mining, construction, and manufacturing industries, has a significant impact on the health of our workforce, costing an estimated $10B in the U.S and causing approximately 425,000 premature deaths world-wide each year. Occupational exposure to particulate metals affects millions of individuals in manufacturing, construction (welding, cutting, blasting), and transportation (combustion, utility maintenance, and repair services) industries. Despite these effects, individual workers are rarely assessed for their exposure to particulate metals, due mainly to the high cost and effort associated with personal exposure measurement. Current exposure assessment methods for particulate metals call for an 8-hour filter sample, after which time, the filter sample is transported to a laboratory and analyzed by inductively-coupled plasma (ICP). The time from sample collection to reporting is typically weeks and costs several hundred dollars per sample. To exacerbate the issue, method detection limits suffer because of sample dilution during digestion. The lack of sensitivity hampers task-based exposure assessment, for which sampling times may be tens of minutes. To address these problems, and as a first step towards using microfluidics for personal exposure assessment, we have developed PADs for measurement of Pb, Cd, Cr, Fe, Ni, and Cu in aerosolized particulate matter.

  3. Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane

    Science.gov (United States)

    Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

    2017-01-01

    We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

  4. A spray-drying strategy for synthesis of nanoscale metal-organic frameworks and their assembly into hollow superstructures

    Science.gov (United States)

    Carné-Sánchez, Arnau; Imaz, Inhar; Cano-Sarabia, Mary; Maspoch, Daniel

    2013-03-01

    Metal-organic frameworks (MOFs) are among the most attractive porous materials known today. Their miniaturization to the nanoscale—into nanoMOFs—is expected to serve myriad applications from drug delivery to membranes, to open up novel avenues to more traditional storage and catalysis applications, and to enable the creation of sophisticated superstructures. Here, we report the use of spray-drying as a versatile methodology to assemble nanoMOFs, yielding spherical hollow superstructures with diameters smaller than 5 µm. This strategy conceptually mimics the emulsions used by chemists to confine the synthesis of materials, but does not require secondary immiscible solvents or surfactants. We demonstrate that the resulting spherical, hollow superstructures can be processed into stable colloids, whose disassembly by sonication affords discrete, homogeneous nanoMOFs. This spray-drying strategy enables the construction of multicomponent MOF superstructures, and the encapsulation of guest species within these superstructures. We anticipate that this will provide new routes to capsules, reactors and composite materials.

  5. The impact of defect scattering on the quasi-ballistic transport of nanoscale conductors

    Energy Technology Data Exchange (ETDEWEB)

    Esqueda, I. S., E-mail: isanchez@isi.edu; Fritze, M. [Information Sciences Institute, University of Southern California, Marina del Rey, California 90292 (United States); Cress, C. D. [Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC 20375 (United States); Cao, Y.; Che, Y.; Zhou, C. [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States)

    2015-02-28

    Using the Landauer approach for carrier transport, we analyze the impact of defects induced by ion irradiation on the transport properties of nanoscale conductors that operate in the quasi-ballistic regime. Degradation of conductance results from a reduction of carrier mean free path due to the introduction of defects in the conducting channel. We incorporate scattering mechanisms from radiation-induced defects into calculations of the transmission coefficient and present a technique for extracting modeling parameters from near-equilibrium transport measurements. These parameters are used to describe degradation in the transport properties of nanoscale devices using a formalism that is valid under quasi-ballistic operation. The analysis includes the effects of bandstructure and dimensionality on the impact of defect scattering and discusses transport properties of nanoscale devices from the diffusive to the ballistic limit. We compare calculations with recently published measurements of irradiated nanoscale devices such as single-walled carbon nanotubes, graphene, and deep-submicron Si metal-oxide-semiconductor field-effect transistors.

  6. Folate-targeted pH-responsive calcium zoledronate nanoscale metal-organic frameworks: Turning a bone antiresorptive agent into an anticancer therapeutic.

    Science.gov (United States)

    Au, Kin Man; Satterlee, Andrew; Min, Yuanzeng; Tian, Xi; Kim, Young Seok; Caster, Joseph M; Zhang, Longzhen; Zhang, Tian; Huang, Leaf; Wang, Andrew Z

    2016-03-01

    Zoledronate (Zol) is a third-generation bisphosphonate that is widely used as an anti-resorptive agent for the treatment of cancer bone metastasis. While there is preclinical data indicating that bisphosphonates such as Zol have direct cytotoxic effects on cancer cells, such effect has not been firmly established in the clinical setting. This is likely due to the rapid absorption of bisphosphonates by the skeleton after intravenous (i.v.) administration. Herein, we report the reformulation of Zol using nanotechnology and evaluation of this novel nanoscale metal-organic frameworks (nMOFs) formulation of Zol as an anticancer agent. The nMOF formulation is comprised of a calcium zoledronate (CaZol) core and a polyethylene glycol (PEG) surface. To preferentially deliver CaZol nMOFs to tumors as well as facilitate cellular uptake of Zol, we incorporated folate (Fol)-targeted ligands on the nMOFs. The folate receptor (FR) is known to be overexpressed in several tumor types, including head-and-neck, prostate, and non-small cell lung cancers. We demonstrated that these targeted CaZol nMOFs possess excellent chemical and colloidal stability in physiological conditions. The release of encapsulated Zol from the nMOFs occurs in the mid-endosomes during nMOF endocytosis. In vitro toxicity studies demonstrated that Fol-targeted CaZol nMOFs are more efficient than small molecule Zol in inhibiting cell proliferation and inducing apoptosis in FR-overexpressing H460 non-small cell lung and PC3 prostate cancer cells. Our findings were further validated in vivo using mouse xenograft models of H460 and PC3. We demonstrated that Fol-targeted CaZol nMOFs are effective anticancer agents and increase the direct antitumor activity of Zol by 80-85% in vivo through inhibition of tumor neovasculature, and inhibiting cell proliferation and inducing apoptosis.

  7. Optical vortex beam generator at nanoscale level

    Science.gov (United States)

    Garoli, Denis; Zilio, Pierfrancesco; Gorodetski, Yuri; Tantussi, Francesco; De Angelis, Francesco

    2016-01-01

    Optical beams carrying orbital angular momentum (OAM) can find tremendous applications in several fields. In order to apply these particular beams in photonic integrated devices innovative optical elements have been proposed. Here we are interested in the generation of OAM-carrying beams at the nanoscale level. We design and experimentally demonstrate a plasmonic optical vortex emitter, based on a metal-insulator-metal holey plasmonic vortex lens. Our plasmonic element is shown to convert impinging circularly polarized light to an orbital angular momentum state capable of propagating to the far-field. Moreover, the emerging OAM can be externally adjusted by switching the handedness of the incident light polarization. The device has a radius of few micrometers and the OAM beam is generated from subwavelength aperture. The fabrication of integrated arrays of PVLs and the possible simultaneous emission of multiple optical vortices provide an easy way to the large-scale integration of optical vortex emitters for wide-ranging applications. PMID:27404659

  8. Monolayer MoS2 metal insulator transition based memcapacitor modeling with extension to a ternary device

    OpenAIRE

    Abdul Karim Khan; Byoung Hun Lee

    2016-01-01

    Memcapacitor model based on its one possible physical realization is developed and simulated in order to know its limitation before making a real device. The proposed device structure consists of vertically stacked dielectric layer and MoS2 monolayer between two external metal plates. The Metal Insulator Transition (MIT) phenomenon of MoS2 monolayer is represented in terms of percolation probabilty which is used as the system state. Cluster based site percolation theory is used to mimic the M...

  9. Surface Preparation and Deposited Gate Oxides for Gallium Nitride Based Metal Oxide Semiconductor Devices

    Directory of Open Access Journals (Sweden)

    Paul C. McIntyre

    2012-07-01

    Full Text Available The literature on polar Gallium Nitride (GaN surfaces, surface treatments and gate dielectrics relevant to metal oxide semiconductor devices is reviewed. The significance of the GaN growth technique and growth parameters on the properties of GaN epilayers, the ability to modify GaN surface properties using in situ and ex situ processes and progress on the understanding and performance of GaN metal oxide semiconductor (MOS devices are presented and discussed. Although a reasonably consistent picture is emerging from focused studies on issues covered in each of these topics, future research can achieve a better understanding of the critical oxide-semiconductor interface by probing the connections between these topics. The challenges in analyzing defect concentrations and energies in GaN MOS gate stacks are discussed. Promising gate dielectric deposition techniques such as atomic layer deposition, which is already accepted by the semiconductor industry for silicon CMOS device fabrication, coupled with more advanced physical and electrical characterization methods will likely accelerate the pace of learning required to develop future GaN-based MOS technology.

  10. Synthesis and application of the novel azomethine metal complexes for the organic electroluminescent devices

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Min; Kim, Jin Soon; Shin, Dong Myung; Kim, Young Kwan; Ha, Yun Kyoung [Hongik Univ., Seoul (Korea, Republic of)

    2001-07-01

    New azomethine metal complexes were synthesized systematically and characterized. Beryllium, magnesium, or zinc ions were used as a central metal cation and aromatic azomethines (L1-L4) were employed as a chelating anionic ligand. Emission peaks of the complexes in both solution and solid states were observed mostly at the region of 400-500 nm in the luminescence spectra, where blue light was emitted. Three of them (BeL1 (I), ZnL2 (II), and ZnL3(III)) were sublimable and thus were applied to the organic light-emitting devices (OLED) as an emitting layer, respectively. The device including the emitting layer of I exhibited white emission with the broad luminescence spectral range. The device with the emitting layer of II showed blue luminescence with the maximum emission peak at 460 nm. Their ionization potentials, electron affinities, and electrochemical band gaps were investigated with cyclic voltammetry. The electrochemical gaps of 2.98 for I, 2.70 for II, and 2.63 eV for III were found to be consistent with their respective optical band gaps of 3.01, 2.95 and 2.61 eV within an experimental error. The structure of OLED manufactured in this study reveals that these complexes can work as electron transporting materials as well.

  11. Safety of magnetic resonance imaging in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices.

    Science.gov (United States)

    Baikoussis, Nikolaos G; Apostolakis, Efstratios; Papakonstantinou, Nikolaos A; Sarantitis, Ioannis; Dougenis, Dimitrios

    2011-06-01

    Magnetic resonance imaging (MRI) in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices is sometimes a risky procedure. Thus MRI in these patients should be performed when it is the only examination able to help with the diagnosis. Moreover the diagnostic benefit must outweigh the risks. Coronary artery stents, prosthetic cardiac valves, metal sternal sutures, mediastinal vascular clips, and epicardial pacing wires are not contraindications for MRI, in contrast to pacemakers and implantable cardioverter-defibrillators. Appropriate patient selection and precautions ensure MRI safety. However it is commonly accepted that although hundreds of patients with pacemakers or implantable cardioverter-defibrillators have undergone safe MRI scanning, it is not a safe procedure. Currently, heating of the pacemaker lead is the major problem undermining MRI safety. According to the US Food and Drug Administration (FDA), there are currently neither "MRI-safe" nor "MRI-compatible" pacemakers and implantable cardioverter-defibrillators. In this article we review the international literature in regard to safety during MRI of patients with implanted cardiac prostheses and metallic cardiovascular electronic devices.

  12. Should in the treatment of osteochondritis dissecans biodegradable or metallic fixation devices be used? A comparative study in goat knees

    NARCIS (Netherlands)

    Wouters, Diederick B.; Bos, Rudolf R. M.; van Horn, Jim R.; van Luyn, Marja J. A.

    2008-01-01

    Most of the metallic devices have to be removed, treating osteochondritis dissecans lesions. This animal study describes the biological and mechanical behavior of screws and pins, made of commercially available PGA/PLA and PLA96 and metallic screws and pins, used for fragment fixation. A sham operat

  13. Synthesis of MnP nanocrystals by treatment of metal carbonyl complexes with phosphines: a new, versatile route to nanoscale transition metal phosphides.

    Science.gov (United States)

    Perera, Susanthri C; Tsoi, Georgy; Wenger, Lowell E; Brock, Stephanie L

    2003-11-19

    The reaction of Mn2(CO)10 with P(SiMe3)3 in coordinating solvents at T >/= 220 degrees C yields low polydispersity, highly crystalline MnP nanoparticles for the first time. The effect of dimensional limiting has resulted in the stabilization of a ferromagnetic ground state at low temperatures, rather than the metamagnetic state observed in bulk (microcrystalline) MnP. The synthetic methodology reported here is demonstrated to be general for a number of different metals and phosphine sources.

  14. Nanoscale solid-state cooling: a review

    Science.gov (United States)

    Ziabari, Amirkoushyar; Zebarjadi, Mona; Vashaee, Daryoosh; Shakouri, Ali

    2016-09-01

    The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal-semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling. Thermomagnetic effects such as magneto-Peltier and Nernst-Ettingshausen cooling are briefly described and recent advances and future trends in these areas are reviewed. The ongoing progress in solid-state cooling concepts such as spin-calorimetrics, electrocalorics, non-equilibrium/nonlinear Peltier devices, superconducting junctions and two-dimensional materials are also elucidated and practical achievements are reviewed. We explain the thermoreflectance thermal imaging microscopy and the transient Harman method as two unique techniques developed for characterization of thermoelectric microrefrigerators. The future prospects for solid-state cooling are briefly summarized.

  15. Nanoscale solid-state cooling: a review.

    Science.gov (United States)

    Ziabari, Amirkoushyar; Zebarjadi, Mona; Vashaee, Daryoosh; Shakouri, Ali

    2016-09-01

    The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal-semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling. Thermomagnetic effects such as magneto-Peltier and Nernst-Ettingshausen cooling are briefly described and recent advances and future trends in these areas are reviewed. The ongoing progress in solid-state cooling concepts such as spin-calorimetrics, electrocalorics, non-equilibrium/nonlinear Peltier devices, superconducting junctions and two-dimensional materials are also elucidated and practical achievements are reviewed. We explain the thermoreflectance thermal imaging microscopy and the transient Harman method as two unique techniques developed for characterization of thermoelectric microrefrigerators. The future prospects for solid-state cooling are briefly summarized.

  16. Chemcatcher and DGT passive sampling devices for regulatory monitoring of trace metals in surface water.

    Science.gov (United States)

    Allan, Ian J; Knutsson, Jesper; Guigues, Nathalie; Mills, Graham A; Fouillac, Anne-Marie; Greenwood, Richard

    2008-07-01

    This work aimed to evaluate whether the performance of passive sampling devices in measuring time-weighted average (TWA) concentrations supports their application in regulatory monitoring of trace metals in surface waters, such as for the European Union's Water Framework Directive (WFD). The ability of the Chemcatcher and the diffusive gradient in thin film (DGT) device sampler to provide comparable TWA concentrations of Cd, Cu, Ni, Pb and Zn was tested through consecutive and overlapping deployments (7-28 days) in the River Meuse (The Netherlands). In order to evaluate the consistency of these TWA labile metal concentrations, these were assessed against total and filtered concentrations measured at relatively high frequencies by two teams using standard monitoring procedures, and metal species predicted by equilibrium speciation modeling using Visual MINTEQ. For Cd and Zn, the concentrations obtained with filtered water samples and the passive sampling devices were generally similar. The samplers consistently underestimated filtered concentrations of Cu and Ni, in agreement with their respective predicted speciation. For Pb, a small labile fraction was mainly responsible for low sampler accumulation and hence high measurement uncertainty. While only the high frequency of spot sampling procedures enabled the observation of higher Cd concentrations during the first 14 days, consecutive DGT deployments were able to detect it and provide a reasonable estimate of ambient concentrations. The range of concentrations measured by spot and passive sampling, for exposures up to 28 days, demonstrated that both modes of monitoring were equally reliable. Passive sampling provides information that cannot be obtained by a realistic spot sampling frequency and this may impact on the ability to detect trends and assess monitoring data against environmental quality standards when concentrations fluctuate.

  17. High sensitive mesoporous TiO2-coated love wave device for heavy metal detection.

    Science.gov (United States)

    Gammoudi, I; Blanc, L; Moroté, F; Grauby-Heywang, C; Boissière, C; Kalfat, R; Rebière, D; Cohen-Bouhacina, T; Dejous, C

    2014-07-15

    This work deals with the design of a highly sensitive whole cell-based biosensor for heavy metal detection in liquid medium. The biosensor is constituted of a Love wave sensor coated with a polyelectrolyte multilayer (PEM). Escherichia coli bacteria are used as bioreceptors as their viscoelastic properties are influenced by toxic heavy metals. The acoustic sensor is constituted of a quartz substrate with interdigitated transducers and a SiO2 guiding layer. However, SiO2 shows some degradation when used in a saline medium. Mesoporous TiO2 presents good mechanical and chemical stability and offers a high active surface area. Then, the addition of a thin titania layer dip-coated onto the acoustic path of the sensor is proposed to overcome the silica degradation and to improve the mass effect sensitivity of the acoustic device. PEM and bacteria deposition, and heavy metal influence, are real time monitored through the resonance frequency variations of the acoustic device. The first polyelectrolyte layer is inserted through the titania mesoporosity, favouring rigid link of the PEM on the sensor and improving the device sensitivity. Also, the mesoporosity of surface increases the specific surface area which can be occupied and favors the formation of homogeneous PEM. It was found a frequency shift near -20±1 kHz for bacteria immobilization with titania film instead of -7±3 kHz with bare silica surface. The sensitivity is highlighted towards cadmium detection. Moreover, in this paper, particular attention is given to the immobilization of bacteria and to biosensor lifetime. Atomic Force Microscopy characterizations of the biosurface have been done for several weeks. They showed significant morphological differences depending on the bacterial life time. We noticed that the lifetime of the biosensor is longer in the case of using a mesoporous TiO2 layer.

  18. Integrated nanoscale tools for interrogating living cells

    Science.gov (United States)

    Jorgolli, Marsela

    The development of next-generation, nanoscale technologies that interface biological systems will pave the way towards new understanding of such complex systems. Nanowires -- one-dimensional nanoscale structures -- have shown unique potential as an ideal physical interface to biological systems. Herein, we focus on the development of nanowire-based devices that can enable a wide variety of biological studies. First, we built upon standard nanofabrication techniques to optimize nanowire devices, resulting in perfectly ordered arrays of both opaque (Silicon) and transparent (Silicon dioxide) nanowires with user defined structural profile, densities, and overall patterns, as well as high sample consistency and large scale production. The high-precision and well-controlled fabrication method in conjunction with additional technologies laid the foundation for the generation of highly specialized platforms for imaging, electrochemical interrogation, and molecular biology. Next, we utilized nanowires as the fundamental structure in the development of integrated nanoelectronic platforms to directly interrogate the electrical activity of biological systems. Initially, we generated a scalable intracellular electrode platform based on vertical nanowires that allows for parallel electrical interfacing to multiple mammalian neurons. Our prototype device consisted of 16 individually addressable stimulation/recording sites, each containing an array of 9 electrically active silicon nanowires. We showed that these vertical nanowire electrode arrays could intracellularly record and stimulate neuronal activity in dissociated cultures of rat cortical neurons similar to patch clamp electrodes. In addition, we used our intracellular electrode platform to measure multiple individual synaptic connections, which enables the reconstruction of the functional connectivity maps of neuronal circuits. In order to expand and improve the capability of this functional prototype device we designed

  19. Transport and photoconduction characteristics of metal-graphene-4H-SiC(0001) heterojunction devices

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, T.; Kouklin, N., E-mail: nkouklin@uwm.edu [Department of Electrical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (United States); Tomer, D.; Rajput, S.; Li, L. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (United States)

    2014-12-01

    Vertically integrated graphene-semiconductor systems remain of significant technological importance for their promise to captivate new device physics and propel the development of advanced carbon-based opto-electronic devices. In this study, we carry out a series of bias-dependent transport, gate-dependent transport, and photoconduction measurements to probe the opto-electronic characteristics of metal-graphene-4H-SiC (0001) (Si-face) heterojunctions. The forward bias transport is found to deviate strongly from thermionic emission one as being controlled by the device circuitry and minority carrier injection mechanisms. An improved analytical model is offered and used to extract key junction parameters including series resistance of ∼80 kΩ, interface barrier height of ∼0.6 eV, and ideality factor of ∼6.1. The results of the photocurrent tests point to a light-assisted minority carrier injection as a key mechanism behind the photoconductive gain obtained in the devices subject to a weak, sub-bandgap cw-excitation.

  20. Controlling Solid-Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells.

    Science.gov (United States)

    Jiang, Chengyang; Hsieh, Yao-Tsung; Zhao, Hongxiang; Zhou, Huanping; Yang, Yang

    2015-09-02

    Using Cu2ZnSn(S,Se)4 (CZTSSe) as a model system, we demonstrate the kinetic control of solid-gas reactions at nanoscale by manipulating the surface chemistry of both sol-gel nanoparticles (NPs) and colloidal nanocrystals (NCs). Specifically, we first identify that thiourea (commonly used as sulfur source in sol-gel processes for metal sulfides) can transform into melamine upon film formation, which serves as surface ligands for as-formed Cu2ZnSnS4 (CZTS) NPs. We further reveal that the presence of these surface ligands can significantly affect the outcome of the solid-gas reactions, which enables us to effectively control the selenization process during the fabrication of CZTSSe solar cells and achieve optimal film morphologies (continuous large grains) by fine-tuning the amount of surface ligands used. Such enhancement leads to better light absorption and allows us to achieve 6.5% efficiency from CZTSSe solar cells processed via a sol-gel process using nontoxic, low boiling point mixed solvents. We believe our discovery that the ligand of particulate precursors can significantly affect solid-gas reactions is universal to solid-state chemistry and will boost further research in both understanding the fundamentals of solid-state reactions at nanoscale and taking advantage of these reactions to fabricate crystalline thin film semiconductors with better morphologies and performances.

  1. Multiplexed Paper Analytical Device for Quantification of Metals using Distance-Based Detection

    Science.gov (United States)

    Cate, David M.; Noblitt, Scott D.; Volckens, John; Henry, Charles S.

    2015-01-01

    Exposure to metal-containing aerosols has been linked with adverse health outcomes for almost every organ in the human body. Commercially available techniques for quantifying particulate metals are time-intensive, laborious, and expensive; often sample analysis exceeds $100. We report a simple technique, based upon a distance-based detection motif, for quantifying metal concentrations of Ni, Cu, and Fe in airborne particulate matter using microfluidic paper-based analytical devices. Paper substrates are used to create sensors that are self-contained, self-timing, and require only a drop of sample for operation. Unlike other colorimetric approaches in paper microfluidics that rely on optical instrumentation for analysis, with distance-based detection, analyte is quantified visually based on the distance of a colorimetric reaction, similar to reading temperature on a thermometer. To demonstrate the effectiveness of this approach, Ni, Cu, and Fe were measured individually in single-channel devices; detection limits as low as 0.1, 0.1, and 0.05 µg were reported for Ni, Cu, and Fe. Multiplexed analysis of all three metals was achieved with detection limits of 1, 5, and 1 µg for Ni, Cu, and Fe. We also extended the dynamic range for multi-analyte detection by printing concentration gradients of colorimetric reagents using an off the shelf inkjet printer. Analyte selectivity was demonstrated for common interferences. To demonstrate utility of the method, Ni, Cu, and Fe were measured from samples of certified welding fume; levels measured with paper sensors matched known values determined gravimetrically. PMID:26009988

  2. Atom Probe Tomography of Nanoscale Electronic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Larson, David J.; Prosa, Ty J.; Perea, Daniel E.; Inoue, Hidekazu; Mangelinck, D.

    2016-01-01

    Atom probe tomography (APT) is a mass spectrometry based on time-of-flight measurements which also concurrently produces 3D spatial information. The reader is referred to any of the other papers in this volume or to the following references for further information 4–8. The current capabilities of APT, such as detecting a low number of dopant atoms in nanoscale devices or segregation at a nanoparticle interface, make this technique an important component in the nanoscale metrology toolbox. In this manuscript, we review some of the applications of APT to nanoscale electronic materials, including transistors and finFETs, silicide contact microstructures, nanowires, and nanoparticles.

  3. Self-assembled nanostructured resistive switching memory devices fabricated by templated bottom-up growth.

    Science.gov (United States)

    Song, Ji-Min; Lee, Jang-Sik

    2016-01-07

    Metal-oxide-based resistive switching memory device has been studied intensively due to its potential to satisfy the requirements of next-generation memory devices. Active research has been done on the materials and device structures of resistive switching memory devices that meet the requirements of high density, fast switching speed, and reliable data storage. In this study, resistive switching memory devices were fabricated with nano-template-assisted bottom up growth. The electrochemical deposition was adopted to achieve the bottom-up growth of nickel nanodot electrodes. Nickel oxide layer was formed by oxygen plasma treatment of nickel nanodots at low temperature. The structures of fabricated nanoscale memory devices were analyzed with scanning electron microscope and atomic force microscope (AFM). The electrical characteristics of the devices were directly measured using conductive AFM. This work demonstrates the fabrication of resistive switching memory devices using self-assembled nanoscale masks and nanomateirals growth from bottom-up electrochemical deposition.

  4. Corrosion development between liquid gallium and four typical metal substrates used in chip cooling device

    Science.gov (United States)

    Deng, Yue-Guang; Liu, Jing

    2009-06-01

    The limitation of the currently available thermal management method has put an ever serious challenge for computer chip designers. A liquid metal with low melting point around room temperature was recently identified as a powerful coolant of driving heat away because of its superior thermo-physical properties and the unique ability to be driven efficiently by a completely silent electromagnetic pump. However, the adoption of gallium, one of the best candidates as metal coolant so far, may cause serious corrosion to the structure materials and subsequently affect the performance or even dangerous running of the cooling system. To address this emerging critical issue, here the compatibility of gallium with four typical metal substrates (6063 Aluminum-Alloy, T2 Copper-Alloy, Anodic Coloring 6063 Aluminum-Alloy and 1Cr18Ni9 Stainless Steel) was comprehensively investigated in order to better understand the corrosion mechanisms and help find out the most suitable structure material for making a liquid metal cooling device. To grasp in detail the dynamic corrosion behavior, an image acquisition and contrasting method was developed. Moreover, corrosion morphology analyses were performed by means of scanning electron microscope (SEM). The chemical compositions of the corroded layers were evaluated using energy dispersive spectrometry (EDS). According to the experiments, it was found that, the corrosion of the 6063 Aluminum-Alloy was rather evident and serious under the temperature range for chip cooling. The loose corrosion product will not only have no protection for the inner substrate, but also accelerate the corrosion process. Compared to the 6063 Aluminum-Alloy, T2 Copper-Alloy showed a slow and general corrosion, but part of the corrosion product can shed from the substrate, which will accelerate corrosion action and may block the flowing channel. Anodic Coloring 6063 Aluminum-Alloy and 1Cr18Ni9 Stainless Steel were found to have excellent corrosion resistance among

  5. Nanoscale waveguiding methods.

    Science.gov (United States)

    Wang, Chia-Jean; Lin, Lih Y

    2007-05-01

    While 32 nm lithography technology is on the horizon for integrated circuit (IC) fabrication, matching the pace for miniaturization with optics has been hampered by the diffraction limit. However, development of nanoscale components and guiding methods is burgeoning through advances in fabrication techniques and materials processing. As waveguiding presents the fundamental issue and cornerstone for ultra-high density photonic ICs, we examine the current state of methods in the field. Namely, plasmonic, metal slot and negative dielectric based waveguides as well as a few sub-micrometer techniques such as nanoribbons, high-index contrast and photonic crystals waveguides are investigated in terms of construction, transmission, and limitations. Furthermore, we discuss in detail quantum dot (QD) arrays as a gain-enabled and flexible means to transmit energy through straight paths and sharp bends. Modeling, fabrication and test results are provided and show that the QD waveguide may be effective as an alternate means to transfer light on sub-diffraction dimensions.

  6. SEMICONDUCTOR DEVICES Density-controllable nonvolatile memory devices having metal nanocrystals through chemical synthesis and assembled by spin-coating technique

    Science.gov (United States)

    Guangli, Wang; Yubin, Chen; Yi, Shi; Lin, Pu; Lijia, Pan; Rong, Zhang; Youdou, Zheng

    2010-12-01

    A novel two-step method is employed, for the first time, to fabricate nonvolatile memory devices that have metal nanocrystals. First, size-averaged Au nanocrystals are synthesized chemically; second, they are assembled into memory devices by a spin-coating technique at room temperature. This attractive approach makes it possible to tailor the diameter and control the density of nanocrystals individually. In addition, processes at room temperature prevent Au diffusion, which is a main concern for the application of metal nanocrystal-based memory. The experimental results, both the morphology characterization and the electrical measurements, reveal that there is an optimum density of nanocrystal monolayer to balance between long data retention and a large hysteresis memory window. At the same time, density-controllable devices could also feed the preferential emphasis on either memory window or retention time. All these facts confirm the advantages and novelty of our two-step method.

  7. Quantum Transport Simulations of Nanoscale Materials

    KAUST Repository

    Obodo, Tobechukwu Joshua

    2016-01-07

    Nanoscale materials have many potential advantages because of their quantum confinement, cost and producibility by low-temperature chemical methods. Advancement of theoretical methods as well as the availability of modern high-performance supercomputers allow us to control and exploit their microscopic properties at the atomic scale, hence making it possible to design novel nanoscale molecular devices with interesting features (e.g switches, rectifiers, negative differential conductance, and high magnetoresistance). In this thesis, state-of-the-art theoretical calculations have been performed for the quantum transport properties of nano-structured materials within the framework of Density Functional Theory (DFT) and the Nonequilibrium Green\\'s Function (NEGF) formalism. The switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes is investigated. The molecule presents a configurational bistability, which can be exploited in constructing molecular memories, switches, and sensors. We find that protonation of the terminating thiol groups is at the origin of the change in conductance. H bonding at the thiol group weakens the S-Au bond, and thus lowers the conductance. Our results allow us to re-interpret the experimental data originally attributing the conductance reduction to H dissociation. Also examined is current-induced migration of atoms in nanoscale devices that plays an important role for device operation and breakdown. We studied the migration of adatoms and defects in graphene and carbon nanotubes under finite bias. We demonstrate that current-induced forces within DFT are non-conservative, which so far has only been shown for model systems, and can lower migration barrier heights. Further, we investigated the quantum transport behavior of an experimentally observed diblock molecule by varying the amounts of phenyl (donor) and pyrimidinyl (acceptor) rings under finite bias. We show that a tandem configuration of

  8. Microplasma devices fabricated in silicon, ceramic, and metal/polymer structures: arrays, emitters and photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Eden, J G [Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Park, S-J [Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Ostrom, N P [Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); McCain, S T [Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Wagner, C J [Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Vojak, B A [Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Chen, J [Microelectronics Laboratory, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Liu, C [Microelectronics Laboratory, Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 (United States); Allmen, P von [Motorola Laboratories, Solid State Research Center, Tempe, AZ 85284 (United States); Zenhausern, F [Motorola Laboratories, Solid State Research Center, Tempe, AZ 85284 (United States); Sadler, D J [Motorola Laboratories, Solid State Research Center, Tempe, AZ 85284 (United States); Jensen, C [Motorola Laboratories, Solid State Research Center, Tempe, AZ 85284 (United States); Wilcox, D L [Motorola Laboratories, Solid State Research Center, Tempe, AZ 85284 (United States); Ewing, J J [Ewing Technology Associates, 5416 143rd Avenue, SE, Bellevue, WA 98006 (United States)

    2003-12-07

    Recent advances in the development of microplasma devices fabricated in a variety of materials systems (Si, ceramic multilayers, and metal/polymer structures) and configurations are reviewed. Arrays of microplasma emitters, having inverted pyramidal Si electrodes or produced in ceramic multilayer sandwiches with integrated ballasting for each pixel, have been demonstrated and arrays as large as 30 x 30 pixels are described. A new class of photodetectors, hybrid semiconductor/microplasma devices, is shown to exhibit photoresponsivities in the visible and near-infrared that are more than an order of magnitude larger than those typical of semiconductor avalanche photodiodes. Microdischarge devices having refractory or piezoelectric dielectric films such as Al{sub 2}O{sub 3} or BN have extended lifetimes ({approx}86% of initial radiant output after 100 h with an Al{sub 2}O{sub 3} dielectric) and controllable electrical characteristics. A segmented, linear array of microdischarges, fabricated in a ceramic multilayer structure and having an active length of {approx}1 cm and a clear aperture of 80 x 360 {mu}m{sup 2}, exhibits evidence of gain on the 460.3 nm transition of Xe{sup +}, making it the first example of a microdischarge-driven optical amplifier.

  9. Microplasma devices fabricated in silicon, ceramic, and metal/polymer structures: arrays, emitters and photodetectors

    Science.gov (United States)

    Eden, J. G.; Park, S.-J.; Ostrom, N. P.; McCain, S. T.; Wagner, C. J.; Vojak, B. A.; Chen, J.; Liu, C.; von Allmen, P.; Zenhausern, F.; Sadler, D. J.; Jensen, C.; Wilcox, D. L.; Ewing, J. J.

    2003-12-01

    Recent advances in the development of microplasma devices fabricated in a variety of materials systems (Si, ceramic multilayers, and metal/polymer structures) and configurations are reviewed. Arrays of microplasma emitters, having inverted pyramidal Si electrodes or produced in ceramic multilayer sandwiches with integrated ballasting for each pixel, have been demonstrated and arrays as large as 30 × 30 pixels are described. A new class of photodetectors, hybrid semiconductor/microplasma devices, is shown to exhibit photoresponsivities in the visible and near-infrared that are more than an order of magnitude larger than those typical of semiconductor avalanche photodiodes. Microdischarge devices having refractory or piezoelectric dielectric films such as Al2O3 or BN have extended lifetimes (~86% of initial radiant output after 100 h with an Al2O3 dielectric) and controllable electrical characteristics. A segmented, linear array of microdischarges, fabricated in a ceramic multilayer structure and having an active length of ~1 cm and a clear aperture of 80 × 360 µm2, exhibits evidence of gain on the 460.3 nm transition of Xe+, making it the first example of a microdischarge-driven optical amplifier.

  10. Sheet Metal Spinning Forming Device%金属薄板旋弯成形装置

    Institute of Scientific and Technical Information of China (English)

    徐智跃

    2012-01-01

    In view of the difficulty in sheet metal bending processing during the new product development phase, the article proposed the new process of spinning forming and corresponding equipment design based on analysis of main structural features of sheet metal parts, and comparison of advantages and disadvantages among the current forming processes as well as their respective applicable range. The paper focuses on structural design, usage and application effect of the sheet metal spinning forming device. [ Ch ,5 fig. 1 tab. 10 ref. ]%针对新产品研制过程中金属薄板弯曲成形这一加工难点,分析了薄板零件主要形状与结构特征,比较了常见成形工艺的优缺点和加工适用的范围,提出旋弯成形这一新的工艺方法及相应工艺装备设计,重点介绍金属薄板旋弯成形装置的结构设计,使用方法及应用效果.

  11. Memory effects in a Al/Ti:HfO2/CuPc metal-oxide-semiconductor device

    Science.gov (United States)

    Tripathi, Udbhav; Kaur, Ramneek

    2016-05-01

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO2) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  12. Memory effects in a Al/Ti:HfO{sub 2}/CuPc metal-oxide-semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Udbhav, E-mail: udbhav1781996@gmail.com; Kaur, Ramneek [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India)

    2016-05-23

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO{sub 2}) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  13. Non-resonant Nanoscale Extreme Light Confinement

    Energy Technology Data Exchange (ETDEWEB)

    Subramania, Ganapathi Subramanian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Huber, Dale L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    A wide spectrum of photonics activities Sandia is engaged in such as solid state lighting, photovoltaics, infrared imaging and sensing, quantum sources, rely on nanoscale or ultrasubwavelength light-matter interactions (LMI). The fundamental understanding in confining electromagnetic power and enhancing electric fields into ever smaller volumes is key to creating next generation devices for these programs. The prevailing view is that a resonant interaction (e.g. in microcavities or surface-plasmon polaritions) is necessary to achieve the necessary light confinement for absorption or emission enhancement. Here we propose new paradigm that is non-resonant and therefore broadband and can achieve light confinement and field enhancement in extremely small areas [~(λ/500)^2 ]. The proposal is based on a theoretical work[1] performed at Sandia. The paradigm structure consists of a periodic arrangement of connected small and large rectangular slits etched into a metal film named double-groove (DG) structure. The degree of electric field enhancement and power confinement can be controlled by the geometry of the structure. The key operational principle is attributed to quasistatic response of the metal electrons to the incoming electromagnetic field that enables non-resonant broadband behavior. For this exploratory LDRD we have fabricated some test double groove structures to enable verification of quasistatic electronic response in the mid IR through IR optical spectroscopy. We have addressed some processing challenges in DG structure fabrication to enable future design of complex sensor and detector geometries that can utilize its non-resonant field enhancement capabilities.].

  14. One-Dimensional (1-D) Nanoscale Heterostructures

    Institute of Scientific and Technical Information of China (English)

    Guozhen SHEN; Di CHEN; Yoshio BANDO; Dmitri GOLBERG

    2008-01-01

    One-dimensional (1-D) nanostructures have been attracted much attention as a result of their exceptional properties, which are different from bulk materials. Among 1-D nanostructures, 1-D heterostructures with modulated compositions and interfaces have recently become of particular interest with respect to potential applications in nanoscale building blocks of future optoelectronic devices and systems. Many kinds of methods have been developed for the synthesis of 1-D nanoscale heterostructures. This article reviews the most recent development, with an emphasize on our own recent efforts, on 1-D nanoscale heterostructures, especially those synthesized from the vapor deposition methods, in which all the reactive precursors are mixed together in the reaction chamber. Three types of 1-D nanoscale heterostructures, defined from their morphologies characteristics, are discussed in detail, which include 1-D co-axial core-shell heterostructures, 1-D segmented heterostructures and hierarchical heterostructures. This article begins with a brief survey of various methods that have been developed for synthesizing 1-D nanoscale heterostructures and then mainly focuses on the synthesis, structures and properties of the above three types of nanoscale heterostructures. Finally, this review concludes with personal views towards the topic of 1-D nanoscale heterostructures.

  15. Metal-Phenolic Carbon Nanocomposites for Robust and Flexible Energy-Storage Devices.

    Science.gov (United States)

    Oh, Jun Young; Jung, Yeonsu; Cho, Young Shik; Choi, Jaeyoo; Youk, Ji Ho; Fechler, Nina; Yang, Seung Jae; Park, Chong Rae

    2017-01-05

    Future electronics applications such as wearable electronics depend on the successful construction of energy-storage devices with superior flexibility and high electrochemical performance. However, these prerequisites are challenging to combine: External forces often cause performance degradation, whereas the trade-off between the required nanostructures for strength and electrochemical performance only results in diminished energy storage. Herein, a flexible supercapacitor based on tannic acid (TA) and carbon nanotubes (CNTs) with a unique nanostructure is presented. TA was self-assembled on the surface of the CNTs by metal-phenolic coordination bonds, which provides the hybrid film with both high strength and high pseudocapacitance. Besides 17-fold increased mechanical strength of the final composite, the hybrid film simultaneously exhibits excellent flexibility and volumetric capacitance.

  16. Two-dimensional linear elasticity theory of magneto-electro-elastic plates considering surface and nonlocal effects for nanoscale device applications

    Science.gov (United States)

    Wang, Wenjun; Li, Peng; Jin, Feng

    2016-09-01

    A novel two-dimensional linear elastic theory of magneto-electro-elastic (MEE) plates, considering both surface and nonlocal effects, is established for the first time based on Hamilton’s principle and the Lee plate theory. The equations derived are more general, suitable for static and dynamic analyses, and can also be reduced to the piezoelectric, piezomagnetic, and elastic cases. As a specific application example, the influences of the surface and nonlocal effects, poling directions, piezoelectric phase materials, volume fraction, damping, and applied magnetic field (i.e., constant applied magnetic field and time-harmonic applied magnetic field) on the magnetoelectric (ME) coupling effects are first investigated based on the established two-dimensional plate theory. The results show that the ME coupling coefficient has an obvious size-dependent characteristic owing to the surface effects, and the surface effects increase the ME coupling effects significantly when the plate thickness decreases to its critical thickness. Below this critical thickness, the size-dependent effect is obvious and must be considered. In addition, the output power density of a magnetic energy nanoharvester is also evaluated using the two-dimensional plate theory obtained, with the results showing that a relatively larger output power density can be achieved at the nanoscale. This study provides a mathematical tool which can be used to analyze the mechanical properties of nanostructures theoretically and numerically, as well as evaluating the size effect qualitatively and quantitatively.

  17. Analysis of Interface Charge Densities for High-k Dielectric Materials based Metal Oxide Semiconductor Devices

    Science.gov (United States)

    Maity, N. P.; Thakur, R. R.; Maity, Reshmi; Thapa, R. K.; Baishya, S.

    2016-10-01

    In this paper, the interface charge densities (Dit) are studied and analyzed for ultra thin dielectric metal oxide semiconductor (MOS) devices using different high-k dielectric materials such as Al2O3, ZrO2 and HfO2. The Dit have been calculated by a new approach using conductance method and it indicates that by reducing the thickness of the oxide, the Dit increases and similar increase is also found by replacing SiO2 with high-k. For the same oxide thickness, SiO2 has the lowest Dit and found to be the order of 1011cm-2eV-1. Linear increase in Dit has been observed as the dielectric constant of the oxide increases. The Dit is found to be in good agreement with published fabrication results at p-type doping level of 1×1017cm-3. Numerical calculations and solutions are performed by MATLAB and device simulation is done by ATLAS.

  18. Optical antennas as nanoscale resonators

    CERN Document Server

    Agio, Mario

    2011-01-01

    Recent progress in nanotechnology has enabled us to fabricate subwavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interaction, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  19. Optical antennas as nanoscale resonators.

    Science.gov (United States)

    Agio, Mario

    2012-02-07

    Recent progress in nanotechnology has enabled us to fabricate sub-wavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review the designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interactions, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  20. Tunable color parallel tandem organic light emitting devices with carbon nanotube and metallic sheet interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, Jorge; Desirena, Haggeo; De la Rosa, Elder [Centro de Investigaciones en Optica, A.P. 1-948, León, Guanajuato 37160 (Mexico); Papadimitratos, Alexios [Solarno Inc., Coppell, Texas 75019 (United States); University of Texas at Dallas, Richardson, Texas 75080 (United States); Zakhidov, Anvar A., E-mail: Zakhidov@utdallas.edu [Solarno Inc., Coppell, Texas 75019 (United States); University of Texas at Dallas, Richardson, Texas 75080 (United States); Energy Efficiency Center, National University of Science and Technology, MISiS, Moscow 119049 (Russian Federation)

    2015-11-21

    Parallel tandem organic light emitting devices (OLEDs) were fabricated with transparent multiwall carbon nanotube sheets (MWCNT) and thin metal films (Al, Ag) as interlayers. In parallel monolithic tandem architecture, the MWCNT (or metallic films) interlayers are an active electrode which injects similar charges into subunits. In the case of parallel tandems with common anode (C.A.) of this study, holes are injected into top and bottom subunits from the common interlayer electrode; whereas in the configuration of common cathode (C.C.), electrons are injected into the top and bottom subunits. Both subunits of the tandem can thus be monolithically connected functionally in an active structure in which each subunit can be electrically addressed separately. Our tandem OLEDs have a polymer as emitter in the bottom subunit and a small molecule emitter in the top subunit. We also compared the performance of the parallel tandem with that of in series and the additional advantages of the parallel architecture over the in-series were: tunable chromaticity, lower voltage operation, and higher brightness. Finally, we demonstrate that processing of the MWCNT sheets as a common anode in parallel tandems is an easy and low cost process, since their integration as electrodes in OLEDs is achieved by simple dry lamination process.

  1. Oscillatory vapour shielding of liquid metal walls in nuclear fusion devices.

    Science.gov (United States)

    van Eden, G G; Kvon, V; van de Sanden, M C M; Morgan, T W

    2017-08-04

    Providing an efficacious plasma facing surface between the extreme plasma heat exhaust and the structural materials of nuclear fusion devices is a major challenge on the road to electricity production by fusion power plants. The performance of solid plasma facing surfaces may become critically reduced over time due to progressing damage accumulation. Liquid metals, however, are now gaining interest in solving the challenge of extreme heat flux hitting the reactor walls. A key advantage of liquid metals is the use of vapour shielding to reduce the plasma exhaust. Here we demonstrate that this phenomenon is oscillatory by nature. The dynamics of a Sn vapour cloud are investigated by exposing liquid Sn targets to H and He plasmas at heat fluxes greater than 5 MW m(-2). The observations indicate the presence of a dynamic equilibrium between the plasma and liquid target ruled by recombinatory processes in the plasma, leading to an approximately stable surface temperature.Vapour shielding is one of the interesting mechanisms for reducing the heat load to plasma facing components in fusion reactors. Here the authors report on the observation of a dynamic equilibrium between the plasma and the divertor liquid Sn surface leading to an overall stable surface temperature.

  2. Fabrication of ultrahigh density metal-cell-metal crossbar memory devices with only two cycles of lithography and dry-etch procedures

    KAUST Repository

    Zong, Baoyu

    2013-05-20

    A novel approach to the fabrication of metal-cell-metal trilayer memory devices was demonstrated by using only two cycles of lithography and dry-etch procedures. The fabricated ultrahigh density crossbar devices can be scaled down to ≤70 nm in half-pitch without alignment issues. Depending on the different dry-etch mechanisms in transferring high and low density nanopatterns, suitable dry-etch angles and methods are studied for the transfer of high density nanopatterns. Some novel process methods have also been developed to eliminate the sidewall and other conversion obstacles for obtaining high density of uniform metallic nanopatterns. With these methods, ultrahigh density trilayer crossbar devices (∼2 × 1010 bit cm-2-kilobit electronic memory), which are composed of built-in practical magnetoresistive nanocells, have been achieved. This scalable process that we have developed provides the relevant industries with a cheap means to commercially fabricate three-dimensional high density metal-cell-metal nanodevices. © 2013 IOP Publishing Ltd.

  3. Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors

    Science.gov (United States)

    Biyikli, Necmi; Haider, Ali

    2017-09-01

    In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.

  4. Kondo Physics at Interfaces in Metallic Non-Local Spin Transport Devices

    Science.gov (United States)

    Leighton, Chris

    2015-03-01

    Despite the maturity of metallic spintronics there remain large gaps in our understanding of spin transport in metals, particularly with injection of spins across ferromagnetic/non-magnetic (FM/NM) interfaces, and their subsequent diffusion and relaxation. Unresolved issues include the limits of applicability of Elliott-Yafet spin relaxation, quantification of the influence of defects, surfaces, and interfaces on spin relaxation at nanoscopic dimensions, and the importance of magnetic and spin-orbit scattering. The non-local spin-valve is an enabling device in this context as, in addition to offering potentially disruptive applications, it allows for the separation of charge and spin currents. One particularly perplexing issue in metallic non-local spin valves is the widely observed non-monotonicity in the T-dependent spin accumulation, where the spin signal actually decreases at low T, in contrast to simple expectations. In this work, by studying an expanded range of FM/NM combinations (encompassing Ni80Fe20, Ni, Fe, Co, Cu, and Al), we demonstrate that this effect is not a property of a given FM or NM, but rather of the FM/NM pair. The non-monotonicity is in fact strongly correlated with the ability of the FM to form a dilute local magnetic moment in the NM. We show that local moments, resulting in this case from the ppm-level tail of the FM/NM interdiffusion profile, suppress the injected spin polarization and diffusion length via a novel manifestation of the Kondo effect, explaining all observations associated with the low T downturn in spin accumulation. We further show: (a) that this effect can be promoted by thermal annealing, at which point the conventional charge transport Kondo effect is simultaneously detected in the NM, and (b) that this suppression in spin accumulation can be quenched, even at interfaces that are highly susceptible to the effect, by insertion of a thin non-moment-supporting interlayer. Important implications for room temperature

  5. Method to determine thermal profiles of nanoscale circuitry

    Science.gov (United States)

    Zettl, Alexander K; Begtrup, Gavi E

    2013-04-30

    A platform that can measure the thermal profiles of devices with nanoscale resolution has been developed. The system measures the local temperature by using an array of nanoscale thermometers. This process can be observed in real time using a high resolution imagining technique such as electron microscopy. The platform can operate at extremely high temperatures.

  6. In-situ spectroscopy and nanoscale electronics in superconductor-topological insulator hybrid devices: a combined thin film growth and quantum transport study

    NARCIS (Netherlands)

    Ngabonziza, Prosper

    2016-01-01

    In this dissertation, we presented a combined thin film growth and quantum transport study on superconductor topological insulator hybrid devices. Understanding of the electronic properties of topological insulators (TIs), their preparation in high quality thin film form and their interaction with o

  7. Coupled modeling of the competitive gettering of transition metals and impact on performance of lifetime sensitive devices

    Science.gov (United States)

    Yazdani, Armin; Chen, Renyu; Dunham, Scott T.

    2017-03-01

    This work models competitive gettering of metals (Cu, Ni, Fe, Mo, and W) by boron, phosphorus, and dislocation loops, and connects those results directly to device performance. Density functional theory calculations were first performed to determine the binding energies of metals to the gettering sites, and based on that, continuum models were developed to model the redistribution and trapping of the metals. Our models found that Fe is most strongly trapped by the dislocation loops while Cu and Ni are most strongly trapped by the P4V clusters formed in high phosphorus concentrations. In addition, it is found that none of the mentioned gettering sites are effective in gettering Mo and W. The calculated metal redistribution along with the associated capture cross sections and trap energy levels are passed to device simulation via the recombination models to calculate carrier lifetime and the resulting device performance. Thereby, a comprehensive and predictive TCAD framework is developed to optimize the processing conditions to maximize performance of lifetime sensitive devices.

  8. Progress of alternative sintering approaches of inkjet-printed metal inks and their application for manufacturing of flexible electronic devices

    NARCIS (Netherlands)

    Wünscher, S.; Abbel, R.; Perelaer, J.; Schubert, U.S.

    2014-01-01

    Well-defined high resolution structures with excellent electrical conductivities are key components of almost every electronic device. Producing these by printing metal based conductive inks on polymer foils represents an important step forward towards the manufacturing of plastic electronic product

  9. The role of bone SPECT/CT in the evaluation of lumbar spinal fusion with metallic fixation devices

    DEFF Research Database (Denmark)

    Damgaard, Morten; Nimb, Lars; Madsen, Jan L

    2010-01-01

    PURPOSE: It is difficult to evaluate the stability of the lumbar spondylodesis with metallic fixation devices by conventional imaging methods such as radiography or magnetic resonance imaging. It is unknown whether single photon emission computed tomography/computed tomography (SPECT/CT) may be u...

  10. The advance on removal of heavy metals in water by nanoscale zero-valent iron%纳米零价铁颗粒去除水中重金属的研究进展

    Institute of Scientific and Technical Information of China (English)

    李钰婷; 张亚雷; 代朝猛; 张伟贤

    2012-01-01

    重金属是毒性大、难降解、易累积的环境污染物,纳米零价铁作为一种新型功能修复材料在去除水体和土壤中重金属方面有着广阔的应用前景.本文综述了纳米零价铁颗粒去除水中重金属的研究进展,包括纳米零价铁的常用制备方法及特性、去除效能、对不同重金属的去除机理以及发展前景和今后的研究方向,以期为该领域的深入研究提供借鉴并拓展新的思路.%Heavy metals are environmental pollutants which are highly toxic,difficult to be biodegraded and easy to enrich.Nanoscale zero-valent iron(nZVI),as a new functional material in environment remediation,has been extensively investigated for removal of heavy metals in waters and soils.In this paper,advance in the removal of heavy metals by nZVI are reviewed.It includes synthesis and characteristics of the nanoparticles,and studies on the removal of heavy metals by nanoparticles such as capabilities,mechanism and perspectives of the technology.

  11. Joule Heating-Induced Metal-Insulator Transition in Epitaxial VO2/TiO2 Devices.

    Science.gov (United States)

    Li, Dasheng; Sharma, Abhishek A; Gala, Darshil K; Shukla, Nikhil; Paik, Hanjong; Datta, Suman; Schlom, Darrell G; Bain, James A; Skowronski, Marek

    2016-05-25

    DC and pulse voltage-induced metal-insulator transition (MIT) in epitaxial VO2 two terminal devices were measured at various stage temperatures. The power needed to switch the device to the ON-state decrease linearly with increasing stage temperature, which can be explained by the Joule heating effect. During transient voltage induced MIT measurement, the incubation time varied across 6 orders of magnitude. Both DC I-V characteristic and incubation times calculated from the electrothermal simulations show good agreement with measured values, indicating Joule heating effect is the cause of MIT with no evidence of electronic effects. The width of the metallic filament in the ON-state of the device was extracted and simulated within the thermal model.

  12. Organic photovoltaic devices comprising solution-processed substituted metal-phthalocyanines and exhibiting near-IR photo-sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, Dominic V.; Mayukh, Mayank; Placencia, Diogenes; Armstrong, Neal R.

    2016-11-29

    Organic photovoltaic (OPV) devices are disclosed. An exemplary device has first and second electrodes and an organic, photovoltaically active zone located between the first and second electrodes. The photovoltaically active zone includes an organic electron-donor material and an organic electron-acceptor material. The electron-donor material includes one or more trivalent- or tetravalent-metal phthalocyanines with alkylchalcogenide ring substituents, and is soluble in at least one organic solvent. This solubility facilitates liquid-processability of the donor material, including formation of thin-films, on an unlimited scale to form planar and bulk heterojunctions in organic OPVs. These donor materials are photovoltaically active in both visible and near-IR wavelengths of light, enabling more of the solar spectrum, for example, to be applied to producing electricity. Also disclosed are methods for producing the metalated phthalocyanines and actual devices.

  13. Nanoscale mass conveyors

    Science.gov (United States)

    Regan, Brian C.; Aloni, Shaul; Zettl, Alexander K.

    2008-03-11

    A mass transport method and device for individually delivering chargeable atoms or molecules from source particles is disclosed. It comprises a channel; at least one source particle of chargeable material fixed to the surface of the channel at a position along its length; a means of heating the channel; and a means for applying an controllable electric field along the channel, whereby the device transports the atoms or molecules along the channel in response to applied electric field. In a preferred embodiment, the mass transport device will comprise a multiwalled carbon nanotube (MWNT), although other one dimensional structures may also be used. The MWNT or other structure acts as a channel for individual or small collections of atoms due to the atomic smoothness of the material. Also preferred is a source particle of a metal such as indium. The particles move by dissociation into small units, in some cases, individual atoms. The particles are preferably less than 100 nm in size.

  14. Mapping nanoscale thermal transfer in-liquid environment-immersion scanning thermal microscopy.

    Science.gov (United States)

    Tovee, Peter D; Kolosov, Oleg V

    2013-11-22

    Nanoscale heat transport is of increasing importance as it often defines performance of modern processors and thermoelectric nanomaterials, and affects functioning of chemical sensors and biosensors. Scanning thermal microscopy (SThM) is the leading tool for nanoscale mapping of thermal properties, but it is often negatively affected by unstable tip-surface thermal contacts. While operating SThM in-liquid environment may allow unimpeded thermal contact and open new application areas, it has so far been regarded as impossible due to increased heat dissipation into the liquid, and the perceived reduced spatial thermal resolution. Nevertheless, in this paper we show that such liquid immersion SThM (iSThM) is fully feasible and, while its thermal sensitivity and spatial resolution is somewhat below that of in-air SThM, it has sufficient thermal contrast to detect thermal conductivity variations in few tens of nm thick graphite nanoflake and metal-polymer nanostructured interconnects. Our results confirm that thermal sensing in iSThM can provide nanoscale resolution on the order of 30 nm, that, coupled with the absence of tip snap-in due to the elimination of capillary forces, opens the possibility for nanoscale thermal mapping in liquids, including thermal phenomena in energy storage devices, catalysts and biosystems.

  15. Selective nanoscale growth of lattice mismatched materials

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Chang; Brueck, Steven R. J.

    2017-06-20

    Exemplary embodiments provide materials and methods of forming high-quality semiconductor devices using lattice-mismatched materials. In one embodiment, a composite film including one or more substantially-single-particle-thick nanoparticle layers can be deposited over a substrate as a nanoscale selective growth mask for epitaxially growing lattice-mismatched materials over the substrate.

  16. Correlation between nanoscale surface potential and power conversion efficiency of P3HT/TiO2 nanorod bulk heterojunction photovoltaic devices.

    Science.gov (United States)

    Wu, Ming-Chung; Wu, Yi-Jen; Yen, Wei-Che; Lo, Hsi-Hsing; Lin, Ching-Fuh; Su, Wei-Fang

    2010-08-01

    This is an in depth study on the surface potential changes of P3HT/TiO(2) nanorod bulk heterojunction thin films. They are affected by interlayer structures, the molecular weight of P3HT, the processing solvents and the surface ligands on the TiO(2). The addition of an electron blocking layer and/or the hole blocking layer to the P3HT/TiO(2) thin film can facilitate charge carrier transport and result in a high surface potential shift. The changes in surface potential of multilayered bulk heterojunction films are closely correlated to their power conversion efficiency of photovoltaic devices. Changing ligand leads to the largest change in surface potential yielding the greatest effect on the power conversion efficiency. Merely changing the P3HT molecular weight is less effective and varying the processing solvents is least effective in increasing power conversion efficiency. The steric effect of the ligand has a large influence on the reduction of charge carrier recombination resulting in a great effect on the power conversion efficiency. By monitoring the changes in the surface potential of bulk heterojunction film of multilayer structures, we have obtained a useful guide for the fabrication of high performance photovoltaic devices.

  17. Spin manipulation in nanoscale superconductors.

    Science.gov (United States)

    Beckmann, D

    2016-04-27

    The interplay of superconductivity and magnetism in nanoscale structures has attracted considerable attention in recent years due to the exciting new physics created by the competition of these antagonistic ordering phenomena, and the prospect of exploiting this competition for superconducting spintronics devices. While much of the attention is focused on spin-polarized supercurrents created by the triplet proximity effect, the recent discovery of long range quasiparticle spin transport in high-field superconductors has rekindled interest in spin-dependent nonequilibrium properties of superconductors. In this review, the experimental situation on nonequilibrium spin injection into superconductors is discussed, and open questions and possible future directions of the field are outlined.

  18. Nanoscale waveguiding methods

    Directory of Open Access Journals (Sweden)

    Wang Chia-Jean

    2007-01-01

    Full Text Available AbstractWhile 32 nm lithography technology is on the horizon for integrated circuit (IC fabrication, matching the pace for miniaturization with optics has been hampered by the diffraction limit. However, development of nanoscale components and guiding methods is burgeoning through advances in fabrication techniques and materials processing. As waveguiding presents the fundamental issue and cornerstone for ultra-high density photonic ICs, we examine the current state of methods in the field. Namely, plasmonic, metal slot and negative dielectric based waveguides as well as a few sub-micrometer techniques such as nanoribbons, high-index contrast and photonic crystals waveguides are investigated in terms of construction, transmission, and limitations. Furthermore, we discuss in detail quantum dot (QD arrays as a gain-enabled and flexible means to transmit energy through straight paths and sharp bends. Modeling, fabrication and test results are provided and show that the QD waveguide may be effective as an alternate means to transfer light on sub-diffraction dimensions.

  19. Nanoscale Measurements of Magnetism & Spin Coherence in Semiconductors

    Science.gov (United States)

    2016-06-14

    2015 Approved for Public Release; Distribution Unlimited Final Report: Nanoscale Measurements of Magnetism & Spin Coherence in Semiconductors The...floor Princeton, NJ 08544 -2020 31-Jul-2015 ABSTRACT Final Report: Nanoscale Measurements of Magnetism & Spin Coherence in Semiconductors Report Title...Si-on-insultor devices. These SOI devices will provide the samples required for study of spin coherence at a single spin level in a semiconductor

  20. An Ionic-Polymer-Metallic Composite Actuator for Reconfigurable Antennas in Mobile Devices

    Directory of Open Access Journals (Sweden)

    Yi-Chen Lin

    2014-01-01

    Full Text Available In this paper, a new application of an electro-active-polymer for a radio frequency (RF switch is presented. We used an ionic polymer metallic composite (IPMC switch to change the operating frequency of an inverted-F antenna. This switch is light in weight, small in volume, and low in cost. In addition, the IPMC is suitable for mobile devices because of its driving voltage of 3 volts and thickness of 200 μm. The IPMC acts as a normally-on switch to control the operating frequency of a reconfigurable antenna in mobile phones. We experimentally demonstrated by network analysis that the IPMC switch could shift its operating frequency from 1.1 to 2.1 GHz, with return losses of than −10 dB at both frequencies. To minimize electrolysis and maximize the operation time in air, propylene carbonate electrolyte with lithium perchlorate (LiClO4 was applied inside the IPMC. The results showed that when the IPMC was actuated over three months at 3.5 V, the tip displacement fell by less than 10%. Therefore, an IPMC actuator is a promising choice for application to a reconfigurable antenna.

  1. Some metal oxides and their applications for creation of Microsystems (MEMS) and Energy Harvesting Devices (EHD)

    Science.gov (United States)

    Denishev, K.

    2016-10-01

    This is a review of a part of the work of the Technological Design Group at Technical University of Sofia, Faculty of Electronic Engineering and Technologies, Department of Microelectronics. It is dealing with piezoelectric polymer materials and their application in different microsystems (MEMS) and Energy Harvesting Devices (EHD), some organic materials and their applications in organic (OLED) displays, some transparent conductive materials etc. The metal oxides Lead Zirconium Titanate (PZT) and Zinc Oxide (ZnO) are used as piezoelectric layers - driving part of different sensors, actuators and EHD. These materials are studied in term of their performance in dependence on the deposition conditions and parameters. They were deposited as thin films by using RF Sputtering System. As technological substrates, glass plates and Polyethylenetherephtalate (PET) foils were used. For characterization of the materials, a test structure, based on Surface Acoustic Waves (SAW), was designed and prepared. The layers were characterized by Fourier Transform Infrared spectroscopy (FTIR). The piezoelectric response was tested at variety of mechanical loads (tensile strain, stress) in static and dynamic (multiple bending) mode. The single-layered and double-layered structures were prepared for piezoelectric efficiency increase. A structure of piezoelectric energy transformer is proposed and investigated.

  2. An ionic-polymer-metallic composite actuator for reconfigurable antennas in mobile devices.

    Science.gov (United States)

    Lin, Yi-Chen; Yu, Chung-Yi; Li, Chung-Min; Liu, Chin-Heng; Chen, Jiun-Peng; Chu, Tah-Hsiung; Su, Guo-Dung John

    2014-01-06

    In this paper, a new application of an electro-active-polymer for a radio frequency (RF) switch is presented. We used an ionic polymer metallic composite (IPMC) switch to change the operating frequency of an inverted-F antenna. This switch is light in weight, small in volume, and low in cost. In addition, the IPMC is suitable for mobile devices because of its driving voltage of 3 volts and thickness of 200 μm. The IPMC acts as a normally-on switch to control the operating frequency of a reconfigurable antenna in mobile phones. We experimentally demonstrated by network analysis that the IPMC switch could shift its operating frequency from 1.1 to 2.1 GHz, with return losses of than -10 dB at both frequencies. To minimize electrolysis and maximize the operation time in air, propylene carbonate electrolyte with lithium perchlorate (LiClO₄) was applied inside the IPMC. The results showed that when the IPMC was actuated over three months at 3.5 V, the tip displacement fell by less than 10%. Therefore, an IPMC actuator is a promising choice for application to a reconfigurable antenna.

  3. Laterally configured resistive switching device based on transition-metal nano-gap electrode on Gd oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Masatoshi; Okabe, Kyota [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kimura, Takashi [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Research Center for Quantum Nano-Spin Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan)

    2016-01-11

    We have developed a fabrication process for a laterally configured resistive switching device based on a Gd oxide. A nano-gap electrode connected by a Gd oxide with the ideal interfaces has been created by adapting the electro-migration method in a metal/GdO{sub x} bilayer system. Bipolar set and reset operations have been clearly observed in the Pt/GdO{sub x} system similarly in the vertical device based on GdO{sub x}. Interestingly, we were able to observe a clear bipolar switching also in a ferromagnetic CoFeB nano-gap electrode with better stability compared to the Pt/GdO{sub x} device. The superior performance of the CoFeB/GdO{sub x} device implies the importance of the spin on the resistive switching.

  4. Effect of Electric Field and Polarity on Light Emission in Metal-Insulator-Semiconductor Structure Thin-Film Electroluminescent Devices

    Science.gov (United States)

    Ohwaki, Jun-ichi; Kozawaguchi, Haruki; Tsujiyama, Bunjiro

    1983-01-01

    Changes in the emission intensities and spectra with applied electric fields in Metal-Insulator-Semiconductor (MIS) structure thin-film electroluminescent (TFEL) devices have been investigated using devices with stacked emitting layer structures, such as ITO/ZnS: Mn/ZnS: Tb/Sm2O3/Al. In MIS-TFEL devices, the emission distribution in the direction of the ZnS film thickness is nonhomogeneous. In particular, the emission intensity in the region near the ZnS-insulator interface increases with increasing applied voltage more than in the other region in the ZnS layer, when electrons exciting emission centers are accelerated from the insulator side. On the other hand, the emission is homogeneous at the opposite polarity. It is found that the emission color for stacked emitting layer MIS-TFEL devices can be modulated by changing the applied voltage.

  5. Monolayer MoS2 metal insulator transition based memcapacitor modeling with extension to a ternary device

    Science.gov (United States)

    Khan, Abdul Karim; Lee, Byoung Hun

    2016-09-01

    Memcapacitor model based on its one possible physical realization is developed and simulated in order to know its limitation before making a real device. The proposed device structure consists of vertically stacked dielectric layer and MoS2 monolayer between two external metal plates. The Metal Insulator Transition (MIT) phenomenon of MoS2 monolayer is represented in terms of percolation probabilty which is used as the system state. Cluster based site percolation theory is used to mimic the MIT of MoS2 which shows slight discontinuous change in MoS2 monolayer conductivity. The metal to insulator transition switches the capacitance of the device in hysterical way. An Ioffe Regel criterion is used to determine the MIT state of MoS2 monolayer. A good control of MIT time in the range of psec is also achieved by changing a single parameter in the model. The model shows memcapacitive behavior with an edge of fast switching (in psec range) over the previous general models. The model is then extended into vertical cascaded version which behaves like a ternary device instead of binary.

  6. Monolayer MoS2 metal insulator transition based memcapacitor modeling with extension to a ternary device

    Directory of Open Access Journals (Sweden)

    Abdul Karim Khan

    2016-09-01

    Full Text Available Memcapacitor model based on its one possible physical realization is developed and simulated in order to know its limitation before making a real device. The proposed device structure consists of vertically stacked dielectric layer and MoS2 monolayer between two external metal plates. The Metal Insulator Transition (MIT phenomenon of MoS2 monolayer is represented in terms of percolation probabilty which is used as the system state. Cluster based site percolation theory is used to mimic the MIT of MoS2 which shows slight discontinuous change in MoS2 monolayer conductivity. The metal to insulator transition switches the capacitance of the device in hysterical way. An Ioffe Regel criterion is used to determine the MIT state of MoS2 monolayer. A good control of MIT time in the range of psec is also achieved by changing a single parameter in the model. The model shows memcapacitive behavior with an edge of fast switching (in psec range over the previous general models. The model is then extended into vertical cascaded version which behaves like a ternary device instead of binary.

  7. Human health and ecological toxicity potentials due to heavy metal content in waste electronic devices with flat panel displays.

    Science.gov (United States)

    Lim, Seong-Rin; Schoenung, Julie M

    2010-05-15

    Display devices such as cathode-ray tube (CRT) televisions and computer monitors are known to contain toxic substances and have consequently been banned from disposal in landfills in the State of California and elsewhere. New types of flat panel display (FPD) devices, millions of which are now purchased each year, also contain toxic substances, but have not previously been systematically studied and compared to assess the potential impact that could result from their ultimate disposal. In the current work, the focus is on the evaluation of end-of-life toxicity potential from the heavy metal content in select FPD devices with the intent to inform material selection and design-for-environment (DfE) decisions. Specifically, the metals antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, selenium, silver, vanadium, and zinc in plasma TVs, LCD (liquid crystal display) TVs, LCD computer monitors and laptop computers are considered. The human health and ecotoxicity potentials are evaluated through a life cycle assessment perspective by combining data on the respective heavy metal contents, the characterization factors in the U.S. EPA Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI), and a pathway and impact model. Principal contributors to the toxicity potentials are lead, arsenic, copper, and mercury. Although the heavy metal content in newer flat panel display devices creates less human health toxicity potential than that in CRTs, for ecological toxicity, the new devices are worse, especially because of the mercury in LCD TVs and the copper in plasma TVs.

  8. Human health and ecological toxicity potentials due to heavy metal content in waste electronic devices with flat panel displays

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seong-Rin [Department of Chemical Engineering and Materials Science, University of California, 2017 Kemper Hall, One Shields Avenue, Davis, CA 95616 (United States); Schoenung, Julie M., E-mail: jmschoenung@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, 2017 Kemper Hall, One Shields Avenue, Davis, CA 95616 (United States)

    2010-05-15

    Display devices such as cathode-ray tube (CRT) televisions and computer monitors are known to contain toxic substances and have consequently been banned from disposal in landfills in the State of California and elsewhere. New types of flat panel display (FPD) devices, millions of which are now purchased each year, also contain toxic substances, but have not previously been systematically studied and compared to assess the potential impact that could result from their ultimate disposal. In the current work, the focus is on the evaluation of end-of-life toxicity potential from the heavy metal content in select FPD devices with the intent to inform material selection and design-for-environment (DfE) decisions. Specifically, the metals antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, selenium, silver, vanadium, and zinc in plasma TVs, LCD (liquid crystal display) TVs, LCD computer monitors and laptop computers are considered. The human health and ecotoxicity potentials are evaluated through a life cycle assessment perspective by combining data on the respective heavy metal contents, the characterization factors in the U.S. EPA Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI), and a pathway and impact model. Principal contributors to the toxicity potentials are lead, arsenic, copper, and mercury. Although the heavy metal content in newer flat panel display devices creates less human health toxicity potential than that in CRTs, for ecological toxicity, the new devices are worse, especially because of the mercury in LCD TVs and the copper in plasma TVs.

  9. Observation of multiple superconducting gaps in Fe1+yTe1-xSex via a nano-scale approach to point-contact spectroscopy

    OpenAIRE

    Peng, Haibing; De, Debtanu; Wu, Zheng; Diaz-Pinto, Carlos

    2012-01-01

    We report a distinct experimental approach to point-contact Andreev reflection spectroscopy with diagnostic capability via a unique design of nano-scale normal metal/superconductor devices with excellent thermo-mechanical stability, and have employed this method to unveil the existence of two superconducting energy gaps in iron chalcogenide Fe1+yTe1-xSex which is crucial for understanding its pairing mechanism. This work opens up new opportunities to study gap structures in superconductors an...

  10. Quantitative evaluation of metal artifacts using different CBCT devices, high-density materials and field of views.

    Science.gov (United States)

    Codari, Marina; de Faria Vasconcelos, Karla; Ferreira Pinheiro Nicolielo, Laura; Haiter Neto, Francisco; Jacobs, Reinhilde

    2017-04-22

    To objectively compare the influence of different cone-beam computed tomography (CBCT) devices, high-density materials and field of views (FOVs) on metal artifact expression. For this in vitro study, three customized acrylic resin phantoms containing high-density materials cylinders: titanium, copper-aluminum alloy and amalgam were scanned on three CBCT devices using high-resolution protocols, same voxel size (0.2 mm) and different FOVs. After fully automatic segmentation and image registration, the same region of interest was defined for the small and medium FOVs. The difference between the segmented and the real volume of the metal cylinders was assessed. Moreover for each segmented slice, the area difference between the segmented and the real axial section was determined. The artifacts on the background were measured as normalizing standard deviation of voxel values in the vicinity of the cylinder, in three different distances. Considerable differences were observed in volume measurements for all CBCTs devices and materials for both FOV sizes (up to 67%). The slice per slice area analysis indicated higher artifacts at the edges of the metal cylinder. Within the materials, amalgam and titanium had, respectively, the worst and best artifact expression in all the CBCT devices. Standard deviation values varied differently between the three distances in each device. Our in vitro study showed that different CBCT devices, high-density materials and FOV should be considered while evaluating CBCT images. More carefully, diagnosis conclusions should be drawn in images containing amalgam and copper-aluminum alloy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Molecular Photovoltaics in Nanoscale Dimension

    Directory of Open Access Journals (Sweden)

    Andrei V. Pakoulev

    2011-01-01

    Full Text Available This review focuses on the intrinsic charge transport in organic photovoltaic (PVC devices and field-effect transistors (SAM-OFETs fabricated by vapor phase molecular self-assembly (VP-SAM method. The dynamics of charge transport are determined and used to clarify a transport mechanism. The 1,4,5,8-naphthalene-tetracarboxylic diphenylimide (NTCDI SAM devices provide a useful tool to study the fundamentals of polaronic transport at organic surfaces and to discuss the performance of organic photovoltaic devices in nanoscale. Time-resolved photovoltaic studies allow us to separate the charge annihilation kinetics in the conductive NTCDI channel from the overall charge kinetic in a SAM-OFET device. It has been demonstrated that tuning of the type of conductivity in NTCDI SAM-OFET devices is possible by changing Si substrate doping. Our study of the polaron charge transfer in organic materials proposes that a cation-radical exchange (redox mechanism is the major transport mechanism in the studied SAM-PVC devices. The role and contribution of the transport through delocalized states of redox active surface molecular aggregates of NTCDI are exposed and investigated. This example of technological development is used to highlight the significance of future technological development of nanotechnologies and to appreciate a structure-property paradigm in organic nanostructures.

  12. Tunable electrical conductivity in metal-organic framework thin film devices

    Energy Technology Data Exchange (ETDEWEB)

    Talin, Albert Alec; Allendorf, Mark D.; Stavila, Vitalie; Leonard, Francois

    2016-08-30

    A composition including a porous metal organic framework (MOF) including an open metal site and a guest species capable of charge transfer that can coordinate with the open metal site, wherein the composition is electrically conductive. A method including infiltrating a porous metal organic framework (MOF) including an open metal site with a guest species that is capable of charge transfer; and coordinating the guest species to the open metal site to form a composition including an electrical conductivity greater than an electrical conductivity of the MOF.

  13. Tunable electrical conductivity in metal-organic framework thin film devices

    Energy Technology Data Exchange (ETDEWEB)

    Talin, Albert Alec; Allendorf, Mark D.; Stavila, Vitalie; Leonard, Francois

    2016-05-24

    A composition including a porous metal organic framework (MOF) including an open metal site and a guest species capable of charge transfer that can coordinate with the open metal site, wherein the composition is electrically conductive. A method including infiltrating a porous metal organic framework (MOF) including an open metal site with a guest species that is capable of charge transfer; and coordinating the guest species to the open metal site to form a composition including an electrical conductivity greater than an electrical conductivity of the MOF.

  14. Efficient and Robust Thermoelectric Power Generation Device Using Hot-Pressed Metal Contacts on Nanostructured Half-Heusler Alloys

    Science.gov (United States)

    Joshi, Giri; Poudel, Bed

    2016-12-01

    We report an efficient thermoelectric device with power density of 8.9 W/cm2 and efficiency of 8.9% at 678°C temperature difference using hot-pressed titanium metal contact layers on nanostructured half-Heusler materials. The high power density and efficiency are due to the efficient nanostructured materials and very low contact resistance of 1 μΩ cm2 between the titanium layer and half-Heusler material. Moreover, the bonding strength between the titanium and half-Heusler is more than 50 MPa, significantly higher compared with conventional contact metallization methods. The low contact resistance and high bonding strength are due to thin-layer diffusion of titanium (600°C). The low contact resistance and high bonding strength result in a stable and efficient power generation device with great potential for use in recovery of waste heat, e.g., in automotive and industrial applications.

  15. Attosecond physics at the nanoscale

    CERN Document Server

    Ciappina, M F; Landsman, A S; Okell, W; Zherebtsov, S; Förg, B; Schötz, J; Seiffert, J L; Fennel, T; Shaaran, T; Zimmermann, T; Chacón, A; Guichard, R; Zaïr, A; Tisch, J W G; Marangos, J P; Witting, T; Braun, A; Maier, S A; Roso, L; Krüger, M; Hommelhoff, P; Kling, M F; Krausz, F; Lewenstein, M

    2016-01-01

    Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds, which is comparable with the optical field. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this article we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spati...

  16. The Fundamental Role of Nano-Scale Oxide Films in the Oxidation of Hydrogen and the Reduction of Oxygen on Noble Metal Electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Digby Macdonald

    2005-04-15

    The derivation of successful fuel cell technologies requires the development of more effective, cheaper, and poison-resistant electrocatalysts for both the anode (H{sub 2} oxidation in the presence of small amounts of CO from the reforming of carbonaceous fuels) and the cathode (reduction of oxygen in the presence of carried-over fuel). The proposed work is tightly focused on one specific aspect of electrocatalysis; the fundamental role(s) played by nanoscale (1-2 nm thick) oxide (''passive'') films that form on the electrocatalyst surfaces above substrate-dependent, critical potentials, on charge transfer reactions, particularly at elevated temperatures (25 C < T < 200 C). Once the role(s) of these films is (are) adequately understood, we will then use this information to specify, at the molecular level, optimal properties of the passive layer for the efficient electrocatalysis of the oxygen reduction reaction.

  17. Matrix-dependent Strain Distributions of Au and Ag Nanoparticles in a Metal-oxide-semiconductor-based Nonvolatile Memory Device

    OpenAIRE

    Honghua Huang; Ying Zhang; Wenyan Wei; Ting Yu; Xingfang Luo; Cailei Yuan

    2015-01-01

    The matrix-dependent strain distributions of Au and Ag nanoparticles in a metal-oxide-semiconductor based nonvolatile memory device are investigated by finite element calculations. The simulation results clearly indicate that both Au and Ag nanoparticles incur compressive strain by high-k Al2O3 and conventional SiO2 dielectrics. The strain distribution of nanoparticles is closely related to the surrounding matrix. Nanoparticles embedded in different matrices experience different compressive s...

  18. Heteroepitaxial growth of 3-5 semiconductor compounds by metal-organic chemical vapor deposition for device applications

    Science.gov (United States)

    Collis, Ward J.; Abul-Fadl, Ali

    1988-01-01

    The purpose of this research is to design, install and operate a metal-organic chemical vapor deposition system which is to be used for the epitaxial growth of 3-5 semiconductor binary compounds, and ternary and quaternary alloys. The long-term goal is to utilize this vapor phase deposition in conjunction with existing current controlled liquid phase epitaxy facilities to perform hybrid growth sequences for fabricating integrated optoelectronic devices.

  19. CMOS compatible nanoscale nonvolatile resistance switching memory.

    Science.gov (United States)

    Jo, Sung Hyun; Lu, Wei

    2008-02-01

    We report studies on a nanoscale resistance switching memory structure based on planar silicon that is fully compatible with CMOS technology in terms of both materials and processing techniques employed. These two-terminal resistance switching devices show excellent scaling potential well beyond 10 Gb/cm2 and exhibit high yield (99%), fast programming speed (5 ns), high on/off ratio (10(3)), long endurance (10(6)), retention time (5 months), and multibit capability. These key performance metrics compare favorably with other emerging nonvolatile memory techniques. Furthermore, both diode-like (rectifying) and resistor-like (nonrectifying) behaviors can be obtained in the device switching characteristics in a controlled fashion. These results suggest that the CMOS compatible, nanoscale Si-based resistance switching devices may be well suited for ultrahigh-density memory applications.

  20. Metal induced crystallized poly-Si-based conductive bridge resistive switching memory device with one transistor and one resistor architecture

    Science.gov (United States)

    Chand, Umesh; Huang, Chun-Yang; Kumar, Dayanand; Tseng, Tseung-Yuen

    2015-11-01

    In this letter, the metal induced crystallization (MIC) process is used in the Si-based conductive bridging resistive random access memory (CBRAM) application. The amorphous Si (a-Si) is transformed to crystallized poly-silicon (poly-Si) at a low temperature by using Ni metal for inducing poly-Si to provide the resistive switching. The MIC process can produce a highly preferred orientation poly-Si film, which can create the exact paths or grain boundaries through the top and down electrodes in the present CBRAM device. The grain boundary in MIC poly-Si layer can confine the conductive filament of metal bridging growth in it, which can improve the switching fluctuation behavior in the nonvolatile memory application. Compared with the a-Si based device, a significant improvement in terms of resistive switching parameters such as stability and resistance distribution is demonstrated in the MIC poly-Si CBRAM device. Moreover, the well-behaved memory performance, such as high ON/OFF resistance ratio (4 order), a large AC endurance (106), and good retention characteristics (104 s at 125 °C) are achieved in the Cu/poly-Si/n+-Si CMOS compatible cross bar structure.

  1. Transparent half metallic g-C4N3 nanotubes: potential multifunctional applications for spintronics and optical devices.

    Science.gov (United States)

    Hu, Tao; Hashmi, Arqum; Hong, Jisang

    2014-08-14

    Multifunctional material brings many interesting issues because of various potential device applications. Using first principles calculations, we predict that the graphitic carbon nitride (g-C4N3) nanotubes can display multifunctional properties for both spintronics and optical device applications. Very interestingly, armchair tubes (n, n) with n = 2, 3, 4, 5, 6 and (5, 0) zigzag tubes are found to be half metallic, while zigzag tubes (n, 0) with n = 4, 6 show an antiferromagnetic ground state with band gaps. However, larger zigzag tubes of (7, 0), (8, 0), and (10, 0) are turned out to be half metallic. Along with the half metallic behavior of the tubes, those tubes seem to be optically transparent in the visible range. Due to these magnetic and optical properties, we suggest that the g-C4N3 nanotubes (CNNTs) can be used for both ideal spintronics and transparent electrode materials. We also explored the stability of magnetic state and nanotube structure using ab initio molecular dynamics. The CNNTs were found to be thermally stable and the magnetic moment was robust against the structural deformation at 300 K. Overall, our theoretical prediction in one dimensional CNNTs may provide a new physics in spintronics and also in other device applications because of potential multifunctional properties.

  2. Preface: Charge transport in nanoscale junctions

    Science.gov (United States)

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-01

    Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at

  3. Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

    Science.gov (United States)

    Almuslem, A. S.; Hanna, A. N.; Yapici, T.; Wehbe, N.; Diallo, E. M.; Kutbee, A. T.; Bahabry, R. R.; Hussain, M. M.

    2017-02-01

    In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO2) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

  4. Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

    KAUST Repository

    Almuslem, A. S.

    2017-02-14

    In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

  5. Alkali Metal Halide Salts as Interface Additives to Fabricate Hysteresis-Free Hybrid Perovskite-Based Photovoltaic Devices.

    Science.gov (United States)

    Wang, Lili; Moghe, Dhanashree; Hafezian, Soroush; Chen, Pei; Young, Margaret; Elinski, Mark; Martinu, Ludvik; Kéna-Cohen, Stéphane; Lunt, Richard R

    2016-09-07

    A new method was developed for doping and fabricating hysteresis-free hybrid perovskite-based photovoltaic devices by using alkali metal halide salts as interface layer additives. Such salt layers introduced at the perovskite interface can provide excessive halide ions to fill vacancies formed during the deposition and annealing process. A range of solution-processed halide salts were investigated. The highest performance of methylammonium lead mixed-halide perovskite device was achieved with a NaI interlayer and showed a power conversion efficiency of 12.6% and a hysteresis of less than 2%. This represents a 90% improvement compared to control devices without this salt layer. Through depth-resolved mass spectrometry, optical modeling, and photoluminescence spectroscopy, this enhancement is attributed to the reduction of iodide vacancies, passivation of grain boundaries, and improved hole extraction. Our approach ultimately provides an alternative and facile route to high-performance and hysteresis-free perovskite solar cells.

  6. Comparison of single-level cervical fusion and a metal-on-metal cervical disc replacement device.

    Science.gov (United States)

    Riina, Joseph; Patel, Amisha; Dietz, John W; Hoskins, Jeffery S; Trammell, Terry R; Schwartz, David D

    2008-04-01

    Cervical fusion is the common treatment for cervical disc disease but can cause secondary disorders. The Prestige ST cervical disc prosthesis (Medtronic Sofamor Danek, Memphis, TN) was designed to preserve spinal motion to potentially limit the secondary disorders. In this article, we report 2-year results from a single-center study comparing use of this device with use of anterior cervical discectomy and fusion (ACDF). Nineteen patients were prospectively randomized to receive the device or to undergo ACDF. Twenty-four months after surgery, patients who received the device demonstrated improvement in neck pain, arm pain, and neurologic function. In our cohort, patients who underwent arthroplasty demonstrated greater improvement in neurologic function and neck pain than patients who underwent cervical discectomy and fusion.

  7. Lessons learnt from metal-on-metal hip arthroplasties will lead to safer innovation for all medical devices.

    Science.gov (United States)

    Hart, Alister J; Sabah, Shiraz A; Henckel, Johann; Lloyd, Gwynneth; Skinner, John A

    2015-01-01

    Metal-on-metal bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing. Large diameter (LD) metal-on-metal (MoM) hips became more prevalent and have been the least successful group of hip implants ever used. They were rapidly adopted from 2004 until the British Hip Society stopped their use in 2012. Well functioning MoM hip results (including the BHR and Metasul) are hidden in the mire of poor results from the group of all MoM bearings.We have reviewed what happened and we make 3 observations. Firstly, collaboration between surgeons and then between surgeons and other disciplines, first identified and then solved the clinical management problems. Secondly, the problems with MoM hips occurred because hip simulation was inadequate at predicting performance in patients. They gave no indications of the biological effects of wear in the human environment. Lastly, retrieval of failed implants was essential to understanding why failure occurred.These lessons must never be forgotten and must form the basis by which new or altered implants are introduced and how they should be monitored. This will enable safer innovation for patients, surgeons and manufacturers. The problems with MoM hips will not have been in vain.

  8. Fabrication and electrical characterization of a MOS memory device containing self-assembled metallic nanoparticles

    Science.gov (United States)

    Sargentis, Ch.; Giannakopoulos, K.; Travlos, A.; Tsamakis, D.

    2007-04-01

    Floating gate devices with nanoparticles embedded in dielectrics have recently attracted much attention due to the fact that these devices operate as non-volatile memories with high speed, high density and low power consumption. In this paper, memory devices containing gold (Au) nanoparticles have been fabricated using e-gun evaporation. The Au nanoparticles are deposited on a very thin SiO 2 layer and are then fully covered by a HfO 2 layer. The HfO 2 is a high- k dielectric and gives good scalability to the fabricated devices. We studied the effect of the deposition parameters to the size and the shape of the Au nanoparticles using capacitance-voltage and conductance-voltage measurements, we demonstrated that the fabricated device can indeed operate as a low-voltage memory device.

  9. Self-dissolution assisted coating on magnesium metal for biodegradable bone fixation devices

    Science.gov (United States)

    Khakbaz, Hadis; Walter, Rhys; Gordon, Timothy; Bobby Kannan, M.

    2014-12-01

    An attempt was made to develop a self-dissolution assisted coating on a pure magnesium metal for potential bone fixation implants. Magnesium phosphate cement (MPC) was coated successfully on the magnesium metal in ammonium dihydrogen phosphate solution. The in vitro degradation behaviour of the MPC coated metal was evaluated using electrochemical techniques. The MPC coating increased the polarisation resistance (RP) of the metal by ˜150% after 2 h immersion in simulated body fluid (SBF) and reduced the corrosion current density (icorr) by ˜80%. The RP of the MPC coated metal remained relatively high even after 8 h immersion period. However, post-degradation analysis of the MPC coated metal revealed localized attack. Hence, the study suggests that MPC coating alone may not be beneficial, but this novel coating could provide additional protection if used as a precursor for other potential coatings such as biodegradable polymers or calcium phosphates.

  10. Metal hydrides as electrode/catalyst materials for oxygen evolution/reduction in electrochemical devices

    Science.gov (United States)

    Bugga, Ratnakumar V. (Inventor); Halpert, Gerald (Inventor); Fultz, Brent (Inventor); Witham, Charles K. (Inventor); Bowman, Robert C. (Inventor); Hightower, Adrian (Inventor)

    1997-01-01

    An at least ternary metal alloy of the formula, AB.sub.(5-Y)X(.sub.y), is claimed. In this formula, A is selected from the rare earth elements, B is selected from the elements of groups 8, 9, and 10 of the periodic table of the elements, and X includes at least one of the following: antimony, arsenic, and bismuth. Ternary or higher-order substitutions, to the base AB.sub.5 alloys, that form strong kinetic interactions with the predominant metals in the base metal hydride are used to form metal alloys with high structural integrity after multiple cycles of hydrogen sorption.

  11. Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Borgatti, F., E-mail: francesco.borgatti@cnr.it [Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Consiglio Nazionale delle Ricerche (CNR), via P. Gobetti 101, Bologna I-40129 (Italy); Torelli, P.; Panaccione, G. [Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, Trieste I-34149 (Italy)

    2016-04-15

    Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

  12. Viable chemical approach for patterning nanoscale magnetoresistive random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taeseung; Kim, Younghee; Chen, Jack Kun-Chieh; Chang, Jane P., E-mail: jpchang@seas.ucla.edu [Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2015-03-15

    A reactive ion etching process with alternating Cl{sub 2} and H{sub 2} exposures has been shown to chemically etch CoFe film that is an integral component in magnetoresistive random access memory (MRAM). Starting with systematic thermodynamic calculations assessing various chemistries and reaction pathways leading to the highest possible vapor pressure of the etch products reactions, the potential chemical combinations were verified by etch rate investigation and surface chemistry analysis in plasma treated CoFe films. An ∼20% enhancement in etch rate was observed with the alternating use of Cl{sub 2} and H{sub 2} plasmas, in comparison with the use of only Cl{sub 2} plasma. This chemical combination was effective in removing metal chloride layers, thus maintaining the desired magnetic properties of the CoFe films. Scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy showed visually and spectroscopically that the metal chloride layers generated by Cl{sub 2} plasma were eliminated with H{sub 2} plasma to yield a clean etch profile. This work suggests that the selected chemistries can be used to etch magnetic metal alloys with a smooth etch profile and this general strategy can be applied to design chemically based etch processes to enable the fabrication of highly integrated nanoscale MRAM devices.

  13. Competing Photocurrent Mechanisms in Quasi-Metallic Carbon Nanotube pn Devices.

    Science.gov (United States)

    Amer, Moh R; Chang, Shun-Wen; Cronin, Stephen B

    2015-07-01

    Photodetectors based on quasi-metallic carbon nanotubes exhibit unique optoelectronic properties. Due to their small bandgap, photocurrent generation is possible at room temperature. The origin of this photocurrent is investigated to determine the underlying mechanism, which can be photothermoelectric effect or photovoltaic effect, depending on the bandgap magnitude of the quasi-metallic nanotube.

  14. Fundamental aspects of metallic impurities and impurity interactions in silicon during device processing

    Energy Technology Data Exchange (ETDEWEB)

    Graff, K. [TEMIC, TELEFUNKEN, Heilbronn (Germany)

    1995-08-01

    A review on the behavior of metallic impurities in silicon can be considerably simplified by a restriction on pure, dislocation-free, monocrystalline silicon. In this case interactions between different impurities and between impurities and grown-in lattice defects can be reduced. This restriction is observed in Chapter 1 for discussing the general behavior of metallic impurities in silicon.

  15. Trace Metals Derived from Electronic Cigarette (ECIG) Generated Aerosol: Potential Problem of ECIG Devices That Contain Nickel.

    Science.gov (United States)

    Palazzolo, Dominic L; Crow, Andrew P; Nelson, John M; Johnson, Robert A

    2016-01-01

    Introduction: ECIGs are currently under scrutiny concerning their safety, particularly in reference to the impact ECIG liquids (E-liquids) have on human health. One concern is that aerosolized E-liquids contain trace metals that could become trapped in respiratory tissues and induce pathology. Methods: To mimic this trapping, peristaltic pumps were used to generate and transport aerosol onto mixed cellulose ester (MCE) membranes where aluminum (Al), arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were subsequently captured and quantified. The presence of trace metals on unexposed MCE membranes and on MCE membranes exposed to mainstream smoke served as control and comparison, respectively. The presence of these metals was also determined from the E-liquid before aerosolization and untouched by the ECIG device. All metals were quantified using ICP-MS. The ECIG core assembly was analyzed using scanning electron microscopy with elemental analysis capability. Results: The contents (μg) of Al, As, Cd, Cu, Fe, Mn, Ni, Pb, and Zn on control MCE membranes were 1.2 ± 0.2, 0.050 ± 0.002, 0.047 ± 0.003, 0.05 ± 0.01, 0.001 ± 0.001, 0.16 ± 0.04, 0.005 ± 0.003, 0.014 ± 0.006, and 0.09 ± 0.02, respectively. The contents of all trace metals on MCE membranes exposed to aerosol were similar to controls, except Ni which was significantly (p metals in E-liquid before aerosolization were negligible compared to amounts of aerosolized E-liquid, except for Fe (0.002 μg before and 0.001 μg after). Elemental analysis of the core assembly reveals the presence of several of these trace metals, especially Al, Fe, Ni, and Zn. Conclusions: In general, from the single ECIG-device/E-liquid combination used, the amount of trace metals from ECIG-generated aerosol are lower than in traditional mainstream smoke, Only Ni in the ECIG-generated aerosol was higher than control. The most probable source of Ni in this aerosol is the core

  16. Metal/Semiconductor and Transparent Conductor/Semiconductor Heterojunctions in High Efficient Photoelectric Devices: Progress and Features

    Directory of Open Access Journals (Sweden)

    M. Melvin David Kumar

    2014-01-01

    Full Text Available Metal/semiconductor and transparent conductive oxide (TCO/semiconductor heterojunctions have emerged as an effective modality in the fabrication of photoelectric devices. This review is following a recent shift toward the engineering of TCO layers and structured Si substrates, incorporating metal nanoparticles for the development of next-generation photoelectric devices. Beneficial progress which helps to increase the efficiency and reduce the cost, has been sequenced based on efficient technologies involved in making novel substrates, TCO layers, and electrodes. The electrical and optical properties of indium tin oxide (ITO and aluminum doped zinc oxide (AZO thin films can be enhanced by structuring the surface of TCO layers. The TCO layers embedded with Ag nanoparticles are used to enhance the plasmonic light trapping effect in order to increase the energy harvesting nature of photoelectric devices. Si nanopillar structures which are fabricated by photolithography-free technique are used to increase light-active surface region. The importance of the structure and area of front electrodes and the effect of temperature at the junction are the value added discussions in this review.

  17. Spatial distribution of heavy metals in the surface soil of source-control stormwater infiltration devices - Inter-site comparison.

    Science.gov (United States)

    Tedoldi, Damien; Chebbo, Ghassan; Pierlot, Daniel; Branchu, Philippe; Kovacs, Yves; Gromaire, Marie-Christine

    2017-02-01

    Stormwater runoff infiltration brings about some concerns regarding its potential impact on both soil and groundwater quality; besides, the fate of contaminants in source-control devices somewhat suffers from a lack of documentation. The present study was dedicated to assessing the spatial distribution of three heavy metals (copper, lead, zinc) in the surface soil of ten small-scale infiltration facilities, along with several physical parameters (soil moisture, volatile matter, variable thickness of the upper horizon). High-resolution samplings and in-situ measurements were undertaken, followed by X-ray fluorescence analyses and spatial interpolation. Highest metal accumulation was found in a relatively narrow area near the water inflow zone, from which concentrations markedly decreased with increasing distance. Maximum enrichment ratios amounted to >20 in the most contaminated sites. Heavy metal patterns give a time-integrated vision of the non-uniform infiltration fluxes, sedimentation processes and surface flow pathways within the devices. This element indicates that the lateral extent of contamination is mainly controlled by hydraulics. The evidenced spatial structure of soil concentrations restricts the area where remediation measures would be necessary in these systems, and suggests possible optimization of their hydraulic functioning towards an easier maintenance. Heterogeneous upper boundary conditions should be taken into account when studying the fate of micropollutants in infiltration facilities with either mathematical modeling or soil coring field surveys.

  18. Nanopatterning and nanoscale devices for biological applications

    CERN Document Server

    Šelimović, Seila

    2014-01-01

    ""This book is a good reference for researchers interested in realizing bio-applications based on micro- and nanostructures, where their interface with liquids and biomolecules is the key point. The most important 'players' of micro- and nano-bioengineering are considered, from DNA to proteins and cells. The work is a good merger of basic concepts and real examples of applications.""-Danilo Demarchi, Politecnico di Torino, Italy

  19. Towards Nanoscale Biomedical Devices in Medicine

    DEFF Research Database (Denmark)

    Parracino, A.; Gajula, G.P.; di Gennaro, A.K.

    2011-01-01

    the immobilization of a PhEst, a S-formylglutathione hydrolase from the psychrophilic P. haloplanktis TAC125 onto the gold coated surface of modified superparamagnetic core-shell nanoparticles (FeO@Au). The synthesis of the nanoparticles is also reported. S-formylglutathione hydrolases constitute a family...

  20. Electromechanical characterization of non-uniform charged ionic polymer-metal composites (IPMC) devices

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, B; Branco, P J C [Institute Superior Tecnico, DEEC - Energia, Lisboa 1096-001 (Portugal)], E-mail: pbranco@ist.utl.pt

    2008-08-15

    Research on electromechanical characterization of non-uniformly charged IPMCs is quasi-absent. This has limited their use to only those devices where the IPMC is completely covered with electrode surfaces (uniformly charged). In this paper, we develop a theoretical study for electromechanical characterization of non-uniformly charged IPMCs. A continuum model taking into account the gravitational forces, important for large IPMCs, is presented. Based on this approach, FEM analysis of IPMC devices using Comsol Multiphysics is introduced in a very simple way. Three devices have been studied, comparing the analytical model results with those ones obtained from a FEM analysis.

  1. Approach to Multifunctional Device Platform with Epitaxial Graphene on Transition Metal Oxide (Postprint)

    Science.gov (United States)

    2015-09-23

    with a metal oxide ( TiO2 ). Our novel direct synthesis of graphene/ TiO2 heterostructure is achieved by C60 deposition on transition Ti metal surface...heterostructures of 2D graphene with a metal oxide ( TiO2 ). Our novel direct synthesis of graphene/ TiO2 heterostructure is achieved by C60 deposition on...5e. TASK NUMBER 0008 5f. WORK UNIT NUMBER X0DV 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER 1

  2. Micro and nanoscale electrochemical systems for reagent generation, coupled electrokinetic transport and enhanced detection

    Science.gov (United States)

    Contento, Nicholas M.

    Chemical analysis is being performed in devices operated at ever decreasing length scales in order to harness the fundamental benefits of micro and nanoscale phenomena while minimizing operating footprint and sample size. The advantages of moving traditional sample or chemical processing steps (e.g. separation, detection, and reaction) into micro- and nanofluidic devices have been demonstrated, and they arise from the relatively rapid rates of heat and mass transport at small length scales. The use of electrochemical methods in micro/nanoscale systems to control and improve these processes holds great promise. Unfortunately, much is still not understood about the coupling of multiple electrode driven processes in a confined environment nor about the fundamental changes in device performance that occur as geometries approach the nanoscale regime. At the nanoscale a significant fraction of the sample volume is in close contact with the device surface, i.e. most of the sample is contained within electronic or diffusion layers associated with surface charge or surface reactions, respectively. The work presented in this thesis aims to understand some fundamental different behaviors observed in micro/nanofluidic structures, particularly those containing one or more embedded, metallic electrode structures. First, a quantitative method is devised to describe the impact of electric fields on electrochemistry in multi-electrode micro/nanofluidic systems. Next the chemical manipulation of small volumes (≤ 10-13 L) in micro/nanofluidic structures is explored by creating regions of high pH and high dissolved gas (H 2) concentration through the electrolysis of H2O. Massively parallel arrays of nanochannel electrodes, or embedded annular nanoband electrodes (EANEs), are then studied with a focus on achieving enhanced signals due to coupled electrokinetic and electrochemical effects. In EANE devices, electroosmotic flow results from the electric field generated between the

  3. Complex-Morphology Metal-Based Nanostructures: Fabrication, Characterization, and Applications

    Directory of Open Access Journals (Sweden)

    Antonella Gentile

    2016-06-01

    Full Text Available Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure. In recent years, many research fields have focused on the synthesis of nanoscale-sized metallic materials with complex shape and composition in order to optimize the optical and electrical response of devices containing metallic nanostructures. The present paper aims to overview the most recent results—in terms of fabrication methodologies, characterization of the physico-chemical properties and applications—of complex-morphology metal-based nanostructures. The paper strongly focuses on the correlation between the complex morphology and the structures’ properties, showing how the morphological complexity (and its nanoscale control can often give access to a wide range of innovative properties exploitable for innovative functional device production. We begin with an overview of the basic concepts on the correlation between structural and optical parameters of nanoscale metallic materials with complex shape and composition, and the possible solutions offered by nanotechnology in a large range of applications (catalysis, electronics, photonics, sensing. The aim is to assess the state of the art, and then show the innovative contributions that can be proposed in this research field. We subsequently report on innovative, versatile and low-cost synthesis techniques, suitable for providing a good control on the size, surface density, composition and geometry of the metallic

  4. Infochemistry Information Processing at the Nanoscale

    CERN Document Server

    Szacilowski, Konrad

    2012-01-01

    Infochemistry: Information Processing at the Nanoscale, defines a new field of science, and describes the processes, systems and devices at the interface between chemistry and information sciences. The book is devoted to the application of molecular species and nanostructures to advanced information processing. It includes the design and synthesis of suitable materials and nanostructures, their characterization, and finally applications of molecular species and nanostructures for information storage and processing purposes. Divided into twelve chapters; the first three chapters serve as an int

  5. Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

    KAUST Repository

    Nassar, Joanna M.

    2014-08-01

    Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

  6. Brazilian device for lapidating large diameter non-lubricated metal seated plug valves for the gas and oil segment

    Energy Technology Data Exchange (ETDEWEB)

    Leite da Silva, Osmar Jose [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    This work is related to a PETROBRAS patent, which defines an alternative technology for maintenance of valves, which are frequently used in the Oil and Gas segment. Until the development of this device, there were no reliable alternatives for the maintenance available at the Brazilian market, thus these valves had to be sent abroad to be repaired. Normally, the maintenance becomes impracticable, due to the high cost and long periods required to accomplish the whole process (send/repair/return). These drawbacks were a decisive impulse to the development of research process, which resulted in the equipment presented here. The Brazilian device for lapidating large diameter metal seated plug valves, that ensures the tightness reliability of these equipment, is being successfully used at PETROBRAS refineries. (author)

  7. Development of Novel Magnetic Metal Oxide Thin Films and Carbon Nanotube Materials for Potential Device Applications

    Science.gov (United States)

    2016-05-09

    materials with applications in areas such as magnetic recording, magnetic sensing devices and high frequency planar microwave devices. Emphasis has been... emission SEM/STEM. For STEM imaging, some nanotubes were scrapped off SiO2 substrate and dispersed in dimethylformamide the resulting solution was dripped...on holey carbon coated carbon TEM grid for SEM and STEM analysis. VSM measurements were carried out using Vector Magnetometer Model 10 VSM system

  8. Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography

    KAUST Repository

    Semple, James

    2017-01-02

    Electronic memory cells are of critical importance in modern-day computing devices, including emerging technology sectors such as large-area printed electronics. One technology that has being receiving significant interest in recent years is resistive switching primarily due to its low dimensionality and nonvolatility. Here, we describe the development of resistive switching memory device arrays based on empty aluminum nanogap electrodes. By employing adhesion lithography, a low-temperature and large-area compatible nanogap fabrication technique, dense arrays of memory devices are demonstrated on both rigid and flexible plastic substrates. As-prepared devices exhibit nonvolatile memory operation with stable endurance, resistance ratios >10⁴ and retention times of several months. An intermittent analysis of the electrode microstructure reveals that controlled resistive switching is due to migration of metal from the electrodes into the nanogap under the application of an external electric field. This alternative form of resistive random access memory is promising for use in emerging sectors such as large-area electronics as well as in electronics for harsh environments, e.g., space, high/low temperature, magnetic influences, radiation, vibration, and pressure.

  9. The role of bone SPECT/CT in the evaluation of lumbar spinal fusion with metallic fixation devices

    DEFF Research Database (Denmark)

    Damgaard, Morten; Nimb, Lars; Madsen, Jan L

    2010-01-01

    PURPOSE: It is difficult to evaluate the stability of the lumbar spondylodesis with metallic fixation devices by conventional imaging methods such as radiography or magnetic resonance imaging. It is unknown whether single photon emission computed tomography/computed tomography (SPECT/CT) may...... be useful to detect a lack of fixation of the pedicle screws and hence to predict instability of the fused vertebral segments. MATERIALS AND METHODS: A retrospective analysis of 9 patients who were referred to bone scintigraphy, including combined SPECT/CT, due to persistent pain or discomfort after...

  10. Grain engineering: How nanoscale inhomogeneities can control charge collection in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    West, Bradley M.; Stuckelberger, Michael; Guthrey, Harvey; Chen, Lei; Lai, Barry; Maser, Jörg; Rose, Volker; Shafarman, William; Al-Jassim, Mowafak; Bertoni, Mariana I.

    2017-02-01

    Statistical and correlative analysis are increasingly important in the design and study of new materials, from semiconductors to metals. Non-destructive measurement techniques, with high spatial resolution, capable of correlating composition and/or structure with device properties, are few and far between. For the case of polycrystalline and inhomogeneous materials, the added challenge is that nanoscale resolution is in general not compatible with the large sampling areas necessary to have a statistical representation of the specimen under study. For the study of grain cores and grain boundaries in polycrystalline solar absorbers this is of particular importance since their dissimilar behavior and variability throughout the samples makes it difficult to draw conclusions and ultimately optimize the material. In this study, we present a nanoscale in-operando approach based on the multimodal utilization of synchrotron nano x-ray fluorescence and x-ray beam induced current collected for grain core and grain boundary areas and correlated pixel-by-pixel in fully operational Cu(In(1-x)Gax)Se2Cu(In(1-x)Gax)Se2 solar cells. We observe that low gallium cells have grain boundaries that over perform compared to the grain cores and high gallium cells have boundaries that under perform. These results demonstrate how nanoscale correlative X-ray microscopy can guide research pathways towards grain engineering low cost, high efficiency solar cells.

  11. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

    OpenAIRE

    2015-01-01

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wa...

  12. 纳米金属有机骨架化合物( NMOFs)的合成及其生物应用%Nanoscale metal-organic frameworks for biomedical imaging and drug delivery

    Institute of Scientific and Technical Information of China (English)

    秦丽洁; 丁亮; 秦长圆; 杨红; 杨仕平

    2012-01-01

    Nanoscale metal-organic frameworks (NMOFs) are a kind of coordination polymers with broad potential applications in biomedical field. This review introduced the synthesis methods of the NMOFs and the latest development of NMOFs as imaging contrast agents and molecular therapeutics. At last we put forward several aspects in this field in the future.%纳米金属有机骨架化合物是在生物医药方面具有广泛潜在应用价值的配位聚合物.从纳米金属有机骨架化合物的合成方法、药物负载、表面修饰以及生物应用等方面介绍了国内外在这一领域的最新进展,并提出了今后需要关注的几个方面,具有一定的参考价值.

  13. Ridge InGaAs/InP multi-quantum-well selective growth in nanoscale trenches on Si (001) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.; Zhou, X.; Li, M.; Kong, X.; Mi, J.; Wang, M.; Wang, W.; Pan, J., E-mail: jqpan@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 (China)

    2016-01-11

    Metal organic chemical vapor deposition of InGaAs/InP multi-quantum-well in nanoscale V-grooved trenches on Si (001) substrate was studied using the aspect ratio trapping method. A high quality GaAs/InP buffer layer with two convex (111) B facets was selectively grown to promote the highly uniform, single-crystal ridge InP/InGaAs multi-quantum-well structure growth. Material quality was confirmed by transmission electron microscopy and room temperature micro-photoluminescence measurements. This approach shows great promise for the fabrication of photonics devices and nanolasers on Si substrate.

  14. Metal assisted catalyzed etched (MACE) black Si: optics and device physics.

    Science.gov (United States)

    Toor, Fatima; Miller, Jeffrey B; Davidson, Lauren M; Duan, Wenqi; Jura, Michael P; Yim, Joanne; Forziati, Joanne; Black, Marcie R

    2016-08-25

    Metal-assisted catalyzed etching (MACE) of silicon (Si) is a controllable, room-temperature wet-chemical technique that uses a thin layer of metal to etch the surface of Si, leaving behind various nano- and micro-scale surface features, including nanowires (NWs), that can be tuned to achieve various useful engineering goals, in particular with respect to Si solar cells. In this review, we introduce the science and technology of MACE from the literature, and provide an in-depth analysis of MACE to enhance Si solar cells, including the outlook for commercial applications of this technology.

  15. Interfaces in nanoscale photovoltaics

    NARCIS (Netherlands)

    Öner, S.Z.

    2016-01-01

    This thesis deals with material interfaces in nanoscale photovoltaics. Interface properties between the absorbing semiconductor and other employed materials are crucial for an efficient solar cell. While the optical properties are largely unaffected by a few nanometer thin layer, the electronic prop

  16. Interfaces in nanoscale photovoltaics

    NARCIS (Netherlands)

    Öner, S.Z.

    2016-01-01

    This thesis deals with material interfaces in nanoscale photovoltaics. Interface properties between the absorbing semiconductor and other employed materials are crucial for an efficient solar cell. While the optical properties are largely unaffected by a few nanometer thin layer, the electronic prop

  17. NANOSCALE PROCESS ENGINEERING

    Institute of Scientific and Technical Information of China (English)

    Qixiang Wang; Fei Wei

    2003-01-01

    The research of nanoscale process engineering (NPE) is based on the interdisciplinary nature of nanoscale science and technology. It mainly deals with transformation of materials and energy into nanostructured materials and nanodevices, and synergizes the multidisciplinary convergence between materials science and technology, biotechnology, and information technology. The core technologies of NPE concern all aspects of nanodevice construction and operation, such as manufacture of nanomaterials "by design", concepts and design of nanoarchitectures, and manufacture and control of customizable nanodevices. Two main targets of NPE at present are focused on nanoscale manufacture and concept design of nanodevices. The research progress of nanoscale manufacturing processes focused on creating nanostructures and assembling them into nanosystems and larger scale architectures has built the interdiscipline of NPE. The concepts and design of smart, multi-functional, environmentally compatible and customizable nanodevice prototypes built from the nanostructured systems of nanocrystalline, nanoporous and microemulsion systems are most challenging tasks of NPE. The development of NPE may also impel us to consider the curriculum and educational reform of chemical engineering in universities.

  18. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores.

    Science.gov (United States)

    El-Safty, Sherif A; Shenashen, Mohamed A; Sakai, Masaru; Elshehy, Emad; Halada, Kohmei

    2015-12-06

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

  19. Pulsed-voltage atom probe tomography of low conductivity and insulator materials by application of ultrathin metallic coating on nanoscale specimen geometry.

    Science.gov (United States)

    Adineh, Vahid R; Marceau, Ross K W; Chen, Yu; Si, Kae J; Velkov, Tony; Cheng, Wenlong; Li, Jian; Fu, Jing

    2017-10-01

    We present a novel approach for analysis of low-conductivity and insulating materials with conventional pulsed-voltage atom probe tomography (APT), by incorporating an ultrathin metallic coating on focused ion beam prepared needle-shaped specimens. Finite element electrostatic simulations of coated atom probe specimens were performed, which suggest remarkable improvement in uniform voltage distribution and subsequent field evaporation of the insulated samples with a metallic coating of approximately 10nm thickness. Using design of experiment technique, an experimental investigation was performed to study physical vapor deposition coating of needle specimens with end tip radii less than 100nm. The final geometries of the coated APT specimens were characterized with high-resolution scanning electron microscopy and transmission electron microscopy, and an empirical model was proposed to determine the optimal coating thickness for a given specimen size. The optimal coating strategy was applied to APT specimens of resin embedded Au nanospheres. Results demonstrate that the optimal coating strategy allows unique pulsed-voltage atom probe analysis and 3D imaging of biological and insulated samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Filling the gap between the quantum and classical worlds of nanoscale magnetism: giant molecular aggregates based on paramagnetic 3d metal ions.

    Science.gov (United States)

    Papatriantafyllopoulou, Constantina; Moushi, Eleni E; Christou, George; Tasiopoulos, Anastasios J

    2016-03-21

    In this review, aspects of the syntheses, structures and magnetic properties of giant 3d and 3d/4f paramagnetic metal clusters in moderate oxidation states are discussed. The term "giant clusters" is used herein to denote metal clusters with nuclearity of 30 or greater. Many synthetic strategies towards such species have been developed and are discussed in this paper. Attempts are made to categorize some of the most successful methods to giant clusters, but it will be pointed out that the characteristics of the crystal structures of such compounds including nuclearity, shape, architecture, etc. are unpredictable depending on the specific structural features of the included organic ligands, reaction conditions and other factors. The majority of the described compounds in this review are of special interest not only for their fascinating nanosized structures but also because they sometimes display interesting magnetic phenomena, such as ferromagnetic exchange interactions, large ground state spin values, single-molecule magnetism behaviour or impressively large magnetocaloric effects. In addition, they often possess the properties of both the quantum and the classical world, and thus their systematic study offers the potential for the discovery of new physical phenomena, as well as a better understanding of the existing ones. The research field of giant clusters is under continuous evolution and their intriguing structural characteristics and magnetism properties that attract the interest of synthetic Inorganic Chemists promise a brilliant future for this class of compounds.

  1. Spin transport and spin injection in mesoscopic metal and semiconductor devices

    NARCIS (Netherlands)

    Van Wees, BJ; Jedema, FJ; Filip, AT; Martin, T; Montambaux, G; ThanhVan, JT

    2001-01-01

    We present our recent experiments on spin dependent transport in mesoscopic systems. First we give a basic theoretical description of spin transport in multiterminal devices. It is shown that multiterminal measurements make it possible to fully isolate the spin valve signal from other spurious (magn

  2. Polymer−metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, S.; Gravesteijn, Dirk J; Soccol, D.; Kapteijn, F.; Sudhölter, E.J.R.; Gascon, J.; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing

  3. Nanoscale Magnetic Materials for Energy-Efficient Spin Based Transistors

    Science.gov (United States)

    Incorvia, Jean Anne Currivan

    In this dissertation, I study the physical behavior of nanoscale magnetic materials and build spin-based transistors that encode information in magnetic domain walls. It can be argued that energy dissipation is the most serious problem in modern electronics, and one that has been resistant to a breakthrough. Wasted heat during computing both wastes energy and hinders further technology scaling. This is an opportunity for physicists and engineers to come up with creative solutions for more energy-efficient computing. I present the device we have designed, called domain wall logic (DW-Logic). Information is stored in the position of a magnetic domain wall in a ferromagnetic wire and read out using a magnetic tunnel junction. This hybrid design uses electrical current as the input and output, keeping the device compatible with charge- based transistors. I build an iterative model to predict both the micromagnetic and circuit behavior of DW- Logic, showing a single device can operate as a universal gate. The model shows we can build complex circuits including an 18-gate Full Adder, and allows us to predict the device switching energy compared to complementary metal-oxide semiconductor (CMOS) transistors. Comparing ?15 nm feature nodes, I find DW-Logic made with perpendicular magnetic anisotropy materials, and utilizing both spin torque transfer and the Spin Hall effect, could operate with 1000x reduced switching energy compared to CMOS. I fabricate DW-Logic device prototypes and show in experiment they can act as AND and NAND gates. I demonstrate that one device can drive two subsequent devices, showing gain, which is a necessary requirement for fanout. I also build a clocked ring oscillator circuit to demonstrate successful bit propagation in a DW-Logic circuit and show that properly scaled devices can have improved operation. Through building the devices, I develop a novel fabrication method for patterning sub-25 nm magnetic wires with very low (˜ 2 nm) average edge

  4. Temperature- and voltage-dependent trap generation model in high-k metal gate MOS device with percolation simulation

    Science.gov (United States)

    Xu, Hao; Yang, Hong; Wang, Yan-Rong; Wang, Wen-Wu; Luo, Wei-Chun; Qi, Lu-Wei; Li, Jun-Feng; Zhao, Chao; Chen, Da-Peng; Ye, Tian-Chun

    2016-08-01

    High-k metal gate stacks are being used to suppress the gate leakage due to tunneling for sub-45 nm technology nodes. The reliability of thin dielectric films becomes a limitation to device manufacturing, especially to the breakdown characteristic. In this work, a breakdown simulator based on a percolation model and the kinetic Monte Carlo method is set up, and the intrinsic relation between time to breakdown and trap generation rate R is studied by TDDB simulation. It is found that all degradation factors, such as trap generation rate time exponent m, Weibull slope β and percolation factor s, each could be expressed as a function of trap density time exponent α. Based on the percolation relation and power law lifetime projection, a temperature related trap generation model is proposed. The validity of this model is confirmed by comparing with experiment results. For other device and material conditions, the percolation relation provides a new way to study the relationship between trap generation and lifetime projection. Project supported by the National High Technology Research and Development Program of China (Grant No. SS2015AA010601), the National Natural Science Foundation of China (Grant Nos. 61176091 and 61306129), and the Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of MicroElectronics of Chinese Academy of Sciences.

  5. Evaluation of radiation damage to Metal-Oxide-Semiconductor (MOS) devices

    Science.gov (United States)

    1982-12-01

    The purpose of these experiments was to provide qualitative and quantitative information on the effects of various hydrogen and nitrogen annealing treatments on the radiation hardness, or resistivity to damage, of MOS capacitors. Toward this end, the following tasks were performed: Construction of capacitor TO-5 packages for device evaluation; The experimental determination of the 1 MHz capacitance-voltage bias curves for both the pre- and post-irradiated capacitors; Evaluation of the change in Flat Band Voltage (Delta V sub fb) for the pre- and post-radiation stressed devices; Compilation of all 1 MHz data for cataloging purposes and the establishment of a benchmark for the new computer automated test system; and Reported data to the Contracting Officer's Technical Representative (COTR) on a case-by-case basis, as time was of the essence.

  6. Electrochemical energy storage devices using electrodes incorporating carbon nanocoils and metal oxides nanoparticles

    KAUST Repository

    Baby, Rakhi Raghavan

    2011-07-28

    Carbon nanocoil (CNC) based electrodes are shown to be promising candidates for electrochemical energy storage applications, provided the CNCs are properly functionalized. In the present study, nanocrystalline metal oxide (RuO 2, MnO2, and SnO2) dispersed CNCs were investigated as electrodes for supercapacitor applications using different electrochemical methods. In the two electrode configuration, the samples exhibited high specific capacitance with values reaching up to 311, 212, and 134 F/g for RuO2/CNCs, MnO2/CNCs, and SnO2/CNCs, respectively. The values obtained for specific capacitance and maximum storage energy per unit mass of the composites were found to be superior to those reported for metal oxide dispersed multiwalled carbon nanotubes in two electrode configuration. In addition, the fabricated supercapacitors retained excellent cycle life with ∼88% of the initial specific capacitance retained after 2000 cycles. © 2011 American Chemical Society.

  7. Bestow metal foams with nanostructured surfaces via a convenient electrochemical method for improved device performance

    Institute of Scientific and Technical Information of China (English)

    Yawen Zhan; Shanshan Zeng; Haidong Bian; Zhe Li; Zhengtao Xu; Jian Lu; Yang Yang Li

    2016-01-01

    Metal foams have been intensively studied as three-dimensional (3-D) bulk mass-support for various applications because of their high conductivities and attractive mechanical properties.However,the relatively low surface area of conventional metal foams largely limits their performance in applications such as charge storage.Here,we present a convenient electrochemical method for addressing this problem using Cu foams as an example.High surface area Cu foams are fabricated in a one-pot one-step manner by repetitive electrodeposition and dealloying treatments.The obtained Cu foams exhibit greatly improved performance for different applications like surface enhanced Raman spectroscopy (SERS) substrates and 3-D bulk supercapacitor electrodes.

  8. Static electric field enhancement in nanoscale structures

    Science.gov (United States)

    Lepetit, Bruno; Lemoine, Didier; Márquez-Mijares, Maykel

    2016-08-01

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  9. Static electric field enhancement in nanoscale structures

    Energy Technology Data Exchange (ETDEWEB)

    Lepetit, Bruno, E-mail: bruno.lepetit@irsamc.ups-tlse.fr; Lemoine, Didier, E-mail: didier.lemoine@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Márquez-Mijares, Maykel, E-mail: mmarquez@instec.cu [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Avenida Salvador Allende 1110, Quinta de los Molinos, La Habana (Cuba)

    2016-08-28

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  10. Cold fiber solid-phase microextraction device based on thermoelectric cooling of metal fiber.

    Science.gov (United States)

    Haddadi, Shokouh Hosseinzadeh; Pawliszyn, Janusz

    2009-04-03

    A new cold fiber solid-phase microextraction device was designed and constructed based on thermoelectric cooling. A three-stage thermoelectric cooler (TEC) was used for cooling a copper rod coated with a poly(dimethylsiloxane) (PDMS) hollow fiber, which served as the solid-phase microextraction (SPME) fiber. The copper rod was mounted on a commercial SPME plunger and exposed to the cold surface of the TEC, which was enclosed in a small aluminum box. A heat sink and a fan were used to dissipate the generated heat at the hot side of the TEC. By applying an appropriate dc voltage to the TEC, the upper part of the copper rod, which was in contact to the cold side of the TEC, was cooled and the hollow fiber reached a lower temperature through heat transfer. A thermocouple was embedded in the cold side of the TEC for indirect measurement of the fiber temperature. The device was applied in quantitative analysis of off-flavors in a rice sample. Hexanal, nonanal, and undecanal were chosen as three off-flavors in rice. They were identified according to their retention times and analyzed by GC-flame ionization detection instrument. Headspace extraction conditions (i.e., temperature and time) were optimized. Standard addition calibration graphs were obtained at the optimized conditions and the concentrations of the three analytes were calculated. The concentration of hexanal was also measured using a conventional solvent extraction method (697+/-143ng/g) which was comparable to that obtained from the cold fiber SPME method (644+/-8). Moreover, the cold fiber SPME resulted in better reproducibility and shorter analysis time. Cold fiber SPME with TEC device can also be used as a portable device for field sampling.

  11. Metal ferrite spinel energy storage devices and methods for making and using same

    Science.gov (United States)

    Weimer, Alan W.; Perkins, Christopher; Scheffe, Jonathan; George, Steven M.; Lichty, Paul

    2013-03-19

    1-100 nm metal ferrite spinel coatings are provided on substrates, preferably by using an atomic layer deposition process. The coatings are able to store energy such as solar energy, and to release that stored energy, via a redox reaction. The coating is first thermally or chemically reduced. The reduced coating is then oxidized in a second step to release energy and/or hydrogen, carbon monoxide or other reduced species.

  12. Multimodality Imaging of the Long-term Vascular Responses Following Implantation of Metallic and Bioresorbable Devices

    OpenAIRE

    Gkogkas, Vasileios

    2014-01-01

    markdownabstract__Abstract__ The pattern of vascular responses following stent/scaffold implantation in conventional interventional practice has been assessed by coronary angiography, intravascular ultrasound or optical coherence tomography and manifests as in-stent vascular response (focal or diffuse) or as edge vascular response (EVR) at the transition zones (focal). The utilization of bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals for coronary revacularizati...

  13. High mobility and high stability glassy metal-oxynitride materials and devices

    Science.gov (United States)

    Lee, Eunha; Kim, Taeho; Benayad, Anass; Hur, Jihyun; Park, Gyeong-Su; Jeon, Sanghun

    2016-04-01

    In thin film technology, future semiconductor and display products with high performance, high density, large area, and ultra high definition with three-dimensional functionalities require high performance thin film transistors (TFTs) with high stability. Zinc oxynitride, a composite of zinc oxide and zinc nitride, has been conceded as a strong substitute to conventional semiconductor film such as silicon and indium gallium zinc oxide due to high mobility value. However, zinc oxynitride has been suffered from poor reproducibility due to relatively low binding energy of nitrogen with zinc, resulting in the instability of composition and its device performance. Here we performed post argon plasma process on zinc oxynitride film, forming nano-crystalline structure in stable amorphous matrix which hampers the reaction of oxygen with zinc. Therefore, material properties and device performance of zinc oxynitride are greatly enhanced, exhibiting robust compositional stability even exposure to air, uniform phase, high electron mobility, negligible fast transient charging and low noise characteristics. Furthermore, We expect high mobility and high stability zinc oxynitride customized by plasma process to be applicable to a broad range of semiconductor and display devices.

  14. Transmission of torque at the nanoscale

    Science.gov (United States)

    Williams, Ian; Oğuz, Erdal C.; Speck, Thomas; Bartlett, Paul; Löwen, Hartmut; Royall, C. Patrick

    2016-01-01

    In macroscopic mechanical devices, torque is transmitted through gearwheels and clutches. In the construction of devices at the nanoscale, torque and its transmission through soft materials will be a key component. However, this regime is dominated by thermal fluctuations leading to dissipation. Here we demonstrate the principle of torque transmission for a disc-like colloidal assembly exhibiting clutch-like behaviour, driven by 27 particles in optical traps. These are translated on a circular path to form a rotating boundary that transmits torque to additional particles confined to the interior. We investigate this transmission and find that it is determined by solid-like or fluid-like behaviour of the device and a stick-slip mechanism reminiscent of macroscopic gearwheels slipping. The transmission behaviour is predominantly governed by the rotation rate of the boundary and the density of the confined system. We determine the efficiency of our device and thus optimize conditions to maximize power output.

  15. BIOCOMPATIBILITY OF MEDICAL DEVICES BASED ON METALS, CAUSES FORMATION OF PATHOLOGICAL REACTIVITY (A REVIEW OF FOREIGN LITERATURE

    Directory of Open Access Journals (Sweden)

    O. M. Rozhnova

    2015-01-01

    Full Text Available The objective of the research is a review of approaches to the evaluation of biocompatibility of medical devices on the basis of metals and alloys, and to find ways of overcoming the low engraftment of implanted structures. Implantation by artificial materials allows us to regain the use of human organs and tissues and to date has no rivals. The advantage of using metals and alloys for implanted structures is their high reliability in operation, long servicelife, and high functionality. The nature of the interaction between the human body and the implant has an impact on resource use and the durability of the structures. Manufacturers of scientific research into medical implants at the present stage are directed to obtain materials that will not adversely affect the human body, and to ensure the maximum survival rate when using them. At the same time, the data presented in the article suggests that attempts to make higher biocompatible material properties tend to reduce the development of new methods for the surface treatment and the chemical composition modulation implants. World literature demonstrates the lack of a systematic approach to the problem of increased sensitivity of patients to different metals and alloys (metal sensitization, resulting in the development of complications such as the development of aseptic inflammation and infectious complications of unstable structures, and loss of functionality. Consequently, there is a need to search for ways to improve the biocompatibility of materials used in medicine, based on an assessment of immune defense mechanisms, and the development of algorithms preoperative tactics. 

  16. Functionalized polymer-iron oxide hybrid nanofibers: Electrospun filtration devices for metal oxyanion removal.

    Science.gov (United States)

    Peter, Katherine T; Johns, Adam J; Myung, Nosang V; Cwiertny, David M

    2017-06-15

    Via a single-pot electrospinning synthesis, we developed a functionalized polymer-metal oxide nanofiber filter for point of use (POU) water treatment of metal oxyanions (e.g., arsenate and chromate). Polyacrylonitrile (PAN) functionalization was accomplished by inclusion of surface-active, quaternary ammonium salts (QAS) [cetyltrimethylammonium bromide (CTAB) or tetrabutylammonium bromide (TBAB)] that provide strong base ion exchange sites. Embedded iron oxide [ferrihydrite (Fh)] nanoparticles were used for their established role as metal sorbents. We examined the influence of QAS and Fh loading on composite properties, including nanofiber morphology, surface area, surface chemical composition, and the accessibility of embedded nanoparticles to solution. Composite performance was then evaluated using kinetic, isotherm, and pH-edge sorption experiments with arsenate and chromate, and benchmarked to unmodified PAN nanofibers and freely dispersed Fh nanoparticles. We also assessed the long-term stability of QAS in the composite matrix. For composites containing QAS or Fh nanoparticles, increasing QAS/Fh nanoparticle loading generally yielded increasing metal oxyanion uptake. The optimized composite (PAN 7 wt%, Fh 3 wt%, TBAB 1 wt%) exhibited two distinct sites for simultaneous, non-competitive metal binding (i.e., iron oxide sites for arsenate removal via sorption and well-retained QAS sites for chromate removal via ion exchange). Moreover, surface-segregating QAS enriched Fh abundance at the nanofiber surface, allowing immobilized nanoparticles to exhibit reactivity comparable to that of unsupported (i.e., suspended or freely dispersed) nanoparticles. To simulate POU application, the optimized composite was tested in a dead-end, flow-through filtration system for arsenate and chromate removal at environmentally relevant concentrations (e.g., μg/L) in both idealized and simulated tap water matrices. Performance trends indicate that dual mechanisms for uptake are

  17. Controlling carrier dynamics at the nanoscale

    Science.gov (United States)

    Cánovas, Enrique; Bonn, Mischa

    2016-10-01

    This Special issue is motivated by the occasion of the International Conference on Charge Carrier Dynamics at the Nanoscale (CCDNano), held in Santiago de Compostela (Spain) in September 2015. As chairs for the CCDNano meeting, we aimed at bringing together experts from different scientific fields in order to trigger interdisciplinary discussions and collaborations; the ultimate goal of the conference was to serve as a platform to advance and help unifying methodologies and theories from different research sub-fields. We also aimed at a deeper understanding of charge dynamics to contribute to the development of improved or novel nanostructured devices. This special issue keeps that spirit, and intends to provide an overview of ongoing research efforts regarding charge carrier dynamics at the nanoscale.

  18. Nanoscale Surface Modification of Layered Materials

    Science.gov (United States)

    O'Shea, Aaron

    2011-11-01

    A scanning electron microscope can magnify a sample many times greater than a standard microscope, down to nanoscale dimensions. It can also be used to form patterns on the surfaces of certain materials, a technique used to create microchips. We have developed a technique that simplifies and expedites this process using an unmodified scanning electron microscope. Using this technique, we are able to alter the surface chemistry in a controlled pattern on a special class of materials called transition metal dichalcogenides. These materials have many useful applications: industrial lubricants; high strength nanocomposites; advanced solar cells; and next generation electronics. Altering the surface chemistry of these materials at the nanoscale results in unusual quantum behavior, which is useful in nanotechnology.

  19. Plasmonic effects in metal-semiconductor nanostructures

    CERN Document Server

    Toropov, Alexey A

    2015-01-01

    Metal-semiconductor nanostructures represent an important new class of materials employed in designing advanced optoelectronic and nanophotonic devices, such as plasmonic nanolasers, plasmon-enhanced light-emitting diodes and solar cells, plasmonic emitters of single photons, and quantum devices operating in infrared and terahertz domains. The combination of surface plasmon resonances in conducting structures, providing strong concentration of an electromagnetic optical field nearby, with sharp optical resonances in semiconductors, which are highly sensitive to external electromagnetic fields, creates a platform to control light on the nanoscale. The design of the composite metal-semiconductor system imposes the consideration of both the plasmonic resonances in metal and the optical transitions in semiconductors - a key issue being their resonant interaction providing a coupling regime. In this book the reader will find descriptions of electrodynamics of conducting structures, quantum physics of semiconducto...

  20. Modelling Methods of Magnetohydrodynamic Phenomena Occurring in a Channel of the Device Used to Wash Out the Spent Automotive Catalyst by a Liquid Metal

    Directory of Open Access Journals (Sweden)

    Fornalczyk A.

    2016-06-01

    Full Text Available The recovery of precious metals is necessary for environmental and economic reasons. Spent catalysts from automotive industry containing precious metals are very attractive recyclable material as the devices have to be periodically renovated and eventually replaced. This paper presents the method of removing platinum from the spent catalytic converters applying lead as a collector metal in a device used to wash out by using mangetohydrodynamic stirrer. The article includes the description of the methods used for modeling of magnetohydrodynamic phenomena (coupled analysis of the electromagnetic, temperature and flow fields occurring in this particular device. The paper describes the general phenomena and ways of coupling the various physical fields for this type of calculation. The basic computational techniques with a discussion of their advantages and disadvantages are presented.