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Sample records for engineered silicon nanostructures

  1. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures

    KAUST Repository

    Mughal, Asad Jahangir

    2014-01-01

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material\\'s luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon. This journal is

  2. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures.

    Science.gov (United States)

    Mughal, A; El Demellawi, J K; Chaieb, Sahraoui

    2014-12-14

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material's luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon.

  3. Polarized electroluminescence from silicon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, Nikolay; Danilovsky, Eduard; Gets, Dmitry; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Mashkov, Vladimir [St. Petersburg State Polytechnical University, 195251 St. Petersburg (Russian Federation)

    2012-05-15

    We present the first findings of the circularly polarized electroluminescence (CPEL) from silicon nanostructures which are the p-type ultra-narrow silicon quantum well (Si-QW) confined by {delta}-barriers heavily doped with boron. The CPEL dependences on the forward current and lateral electric field show the circularly polarized light emission which appears to be caused by the exciton recombination through the negative-U dipole boron centers at the Si-QW-{delta}-barriers interface with the assistance of phosphorus donors. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. On nanostructured silicon success

    DEFF Research Database (Denmark)

    Sigmund, Ole; Jensen, Jakob Søndergaard; Frandsen, Lars Hagedorn

    2016-01-01

    Recent Letters by Piggott et al. 1 and Shen et al. 2 claim the smallest ever dielectric wave length and polarization splitters. The associated News & Views article by Aydin3 states that these works “are the first experimental demonstration of on-chip, silicon photonic components based on complex...

  5. Simple Approach to Superamphiphobic Overhanging Silicon Nanostructures

    DEFF Research Database (Denmark)

    Kumar, Rajendra; Mogensen, Klaus Bo; Bøggild, Peter

    2010-01-01

    Superhydrophobic silicon nanostructures were fabricated by anisotropic etching of silicon coated with a thin hydrophobic layer. At certain etch parameters, overhanging nanostructures form at the apexes of the rod-shaped tips, This leads to superoleophobic behavior for several oily liquids...

  6. Tuning the Color of Silicon Nanostructures

    KAUST Repository

    Cao, Linyou

    2010-07-14

    Empowering silicon (Si) with optical functions constitutes a very important challenge in photonics. The scalable fabrication capabilities for this earth-abundant, environmentally friendly material are unmatched in sophistication and can be unleashed to realize a plethora of high-performance photonic functionalities that find application in information, bio-, display, camouflage, ornamental, and energy technologies. Nanofashioning represents a general strategy to turn Si into a useful optical material and Si structures have already been engineered to enable light emission, optical cloaking, waveguiding, nonlinear optics, enhanced light absorption, and sensing. Here, we demonstrate that a wide spectrum of colors can be generated by harnessing the strong resonant light scattering properties of Si nanostructures under white light illumination. The ability to engineer such colors in a predetermined fashion through a choice of the structure size, dielectric environment, and illumination conditions opens up entirely new applications of Si and puts this material in a new light. © 2010 American Chemical Society.

  7. Phonon engineering for nanostructures.

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, Sylvie (Stanford University); Friedmann, Thomas Aquinas; Sullivan, John Patrick; Peebles, Diane Elaine; Hurley, David H. (Idaho National Laboratory); Shinde, Subhash L.; Piekos, Edward Stanley; Emerson, John Allen

    2010-01-01

    Understanding the physics of phonon transport at small length scales is increasingly important for basic research in nanoelectronics, optoelectronics, nanomechanics, and thermoelectrics. We conducted several studies to develop an understanding of phonon behavior in very small structures. This report describes the modeling, experimental, and fabrication activities used to explore phonon transport across and along material interfaces and through nanopatterned structures. Toward the understanding of phonon transport across interfaces, we computed the Kapitza conductance for {Sigma}29(001) and {Sigma}3(111) interfaces in silicon, fabricated the interfaces in single-crystal silicon substrates, and used picosecond laser pulses to image the thermal waves crossing the interfaces. Toward the understanding of phonon transport along interfaces, we designed and fabricated a unique differential test structure that can measure the proportion of specular to diffuse thermal phonon scattering from silicon surfaces. Phonon-scale simulation of the test ligaments, as well as continuum scale modeling of the complete experiment, confirmed its sensitivity to surface scattering. To further our understanding of phonon transport through nanostructures, we fabricated microscale-patterned structures in diamond thin films.

  8. Silicon nanostructures for cancer diagnosis and therapy.

    Science.gov (United States)

    Peng, Fei; Cao, Zhaohui; Ji, Xiaoyuan; Chu, Binbin; Su, Yuanyuan; He, Yao

    2015-01-01

    The emergence of nanotechnology suggests new and exciting opportunities for early diagnosis and therapy of cancer. During the recent years, silicon-based nanomaterials featuring unique properties have received great attention, showing high promise for myriad biological and biomedical applications. In this review, we will particularly summarize latest representative achievements on the development of silicon nanostructures as a powerful platform for cancer early diagnosis and therapy. First, we introduce the silicon nanomaterial-based biosensors for detecting cancer markers (e.g., proteins, tumor-suppressor genes and telomerase activity, among others) with high sensitivity and selectivity under molecular level. Then, we summarize in vitro and in vivo applications of silicon nanostructures as efficient nanoagents for cancer therapy. Finally, we discuss the future perspective of silicon nanostructures for cancer diagnosis and therapy.

  9. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

    2014-10-30

    This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

  10. Quantum Optomechanics with Silicon Nanostructures

    Science.gov (United States)

    Safavi-Naeini, Amir H.

    Mechanical resonators are the most basic and ubiquitous physical systems known. In on-chip form, they are used to process high frequency signals in every cell phone, television, and laptop. They have also been in the last few decades in different shapes and forms, a critical part of progress in quantum information sciences with kilogram scale mirrors for gravitational wave detection measuring motion at its quantum limits, and the motion of single ions being used to link qubits for quantum computation. Optomechanics is a field primarily concerned with coupling light to the motion of mechanical structures. This thesis contains descriptions of recent work with mechanical systems in the megahertz to gigahertz frequency range, formed by nanofabricating novel photonic/phononic structures on a silicon chip. These structures are designed to have both optical and mechanical resonances, and laser light is used to address and manipulate their motional degrees of freedom through radiation pressure forces. We laser cool these mechanical resonators to their ground states, and observe for the first time the quantum zero-point motion of a nanomechanical resonator. Conversely, we show that engineered mechanical resonances drastically modify the optical response of our structures, creating large effective optical nonlinearities not present in bulk silicon. We experimentally demonstrate aspects of these nonlinearities by proposing and observing ``electromagnetically induced transparency'' and light slowed down to 6 m/s, as well as wavelength conversion, and generation of nonclassical optical radiation. Finally, the application of optomechanics to longstanding problems in quantum and classical communications are proposed and investigated.

  11. Thermoelectric properties of nanostructured porous silicon

    Science.gov (United States)

    Martín-Palma, R. J.; Cabrera, H.; Martín-Adrados, B.; Korte, D.; Pérez-Cappe, E.; Mosqueda, Y.; Frutis, M. A.; Danguillecourt, E.

    2018-01-01

    In this work we report on the thermoelectric properties of nanostructured porous silicon (nanoPS) layers grown onto silicon substrates. More specifically, nanoPS layers of different porosity, nanocrystal size, and thickness were fabricated and their electrical conductivities, Seebeck coefficients, and thermal conductivities were subsequently measured. It was found that these parameters show a strong dependence on the characteristics of the nanoPS layers and thus can be controlled.

  12. Silicon-embedded copper nanostructure network for high energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Tianyue

    2018-01-23

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  13. Silicon-embedded copper nanostructure network for high energy storage

    Science.gov (United States)

    Yu, Tianyue

    2016-03-15

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  14. Printable nanostructured silicon solar cells for high-performance, large-area flexible photovoltaics.

    Science.gov (United States)

    Lee, Sung-Min; Biswas, Roshni; Li, Weigu; Kang, Dongseok; Chan, Lesley; Yoon, Jongseung

    2014-10-28

    Nanostructured forms of crystalline silicon represent an attractive materials building block for photovoltaics due to their potential benefits to significantly reduce the consumption of active materials, relax the requirement of materials purity for high performance, and hence achieve greatly improved levelized cost of energy. Despite successful demonstrations for their concepts over the past decade, however, the practical application of nanostructured silicon solar cells for large-scale implementation has been hampered by many existing challenges associated with the consumption of the entire wafer or expensive source materials, difficulties to precisely control materials properties and doping characteristics, or restrictions on substrate materials and scalability. Here we present a highly integrable materials platform of nanostructured silicon solar cells that can overcome these limitations. Ultrathin silicon solar microcells integrated with engineered photonic nanostructures are fabricated directly from wafer-based source materials in configurations that can lower the materials cost and can be compatible with deterministic assembly procedures to allow programmable, large-scale distribution, unlimited choices of module substrates, as well as lightweight, mechanically compliant constructions. Systematic studies on optical and electrical properties, photovoltaic performance in experiments, as well as numerical modeling elucidate important design rules for nanoscale photon management with ultrathin, nanostructured silicon solar cells and their interconnected, mechanically flexible modules, where we demonstrate 12.4% solar-to-electric energy conversion efficiency for printed ultrathin (∼ 8 μm) nanostructured silicon solar cells when configured with near-optimal designs of rear-surface nanoposts, antireflection coating, and back-surface reflector.

  15. Lifetime of Nano-Structured Black Silicon for Photovoltaic Applications

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    2016-01-01

    properties. We applied reactive ion etching technology at -20ºC to create nano-structures on silicon samples and obtained an average reflectance below 0.5%. For passivation purposes, we used 37 nm ALD Al2O3 films. Lifetime measurements resulted in 1220 µs and to 4170 µs for p- and ntype CZ silicon wafers......, respectively. This is promising for use of black silicon RIE nano-structuring in a solar cell process flow...

  16. Stress Controlled Catalysis via Engineered Nanostructures

    Science.gov (United States)

    2016-03-02

    fields on catalysis : “Stress Controlled Catalysis via Engineered Nanostructures.” For this effort a workshop was organized and held at Brown... Catalysis via Engineered Nanostructures" The views, opinions and/or findings contained in this report are those of the author(s) and should not contrued...Support for current award "Stress Controlled Catalysis via Engineered Nanostructures" Report Title This is the final report of the ARO project of

  17. Superhydrophobic SERS substrates based on silicon hierarchical nanostructures

    Science.gov (United States)

    Chen, Xuexian; Wen, Jinxiu; Zhou, Jianhua; Zheng, Zebo; An, Di; Wang, Hao; Xie, Weiguang; Zhan, Runze; Xu, Ningsheng; Chen, Jun; She, Juncong; Chen, Huanjun; Deng, Shaozhi

    2018-02-01

    Silicon nanostructures have been cultivated as promising surface enhanced Raman scattering (SERS) substrates in terms of their low-loss optical resonance modes, facile functionalization, and compatibility with today’s state-of-the-art CMOS techniques. However, unlike their plasmonic counterparts, the electromagnetic field enhancements induced by silicon nanostructures are relatively small, which restrict their SERS sensing limit to around 10-7 M. To tackle this problem, we propose here a strategy for improving the SERS performance of silicon nanostructures by constructing silicon hierarchical nanostructures with a superhydrophobic surface. The hierarchical nanostructures are binary structures consisted of silicon nanowires (NWs) grown on micropyramids (MPs). After being modified with perfluorooctyltriethoxysilane (PFOT), the nanostructure surface shows a stable superhydrophobicity with a high contact angle of ˜160°. The substrate can allow for concentrating diluted analyte solutions into a specific area during the evaporation of the liquid droplet, whereby the analytes are aggregated into a small volume and can be easily detected by the silicon nanostructure SERS substrate. The analyte molecules (methylene blue: MB) enriched from an aqueous solution lower than 10-8 M can be readily detected. Such a detection limit is ˜100-fold lower than the conventional SERS substrates made of silicon nanostructures. Additionally, the detection limit can be further improved by functionalizing gold nanoparticles onto silicon hierarchical nanostructures, whereby the superhydrophobic characteristics and plasmonic field enhancements can be combined synergistically to give a detection limit down to ˜10-11 M. A gold nanoparticle-functionalized superhydrophobic substrate was employed to detect the spiked melamine in liquid milk. The results showed that the detection limit can be as low as 10-5 M, highlighting the potential of the proposed superhydrophobic SERS substrate in

  18. Plasma-made silicon nanograss and related nanostructures

    International Nuclear Information System (INIS)

    Shieh, Jiann; Ravipati, Srikanth; Ko, Fu-Hsiang; Ostrikov, Kostya

    2011-01-01

    Plasma-made nanostructures show outstanding potential for applications in nanotechnology. This paper provides a concise overview on the progress of plasma-based synthesis and applications of silicon nanograss and related nanostructures. The materials described here include black silicon, Si nanotips produced using a self-masking technique as well as self-organized silicon nanocones and nanograss. The distinctive features of the Si nanograss, two-tier hierarchical and tilted nanograss structures are discussed. Specific applications based on the unique features of the silicon nanograss are also presented.

  19. Spin coherence in silicon/silicon-germanium nanostructures

    Science.gov (United States)

    Truitt, James L.

    This thesis investigates the spin coherence of electrons in silicon/silicon-germanium (Si/SiGe) quantum wells. With a long spin coherence time, an electron trapped in a quantum dot in Si/SiGe is a prime candidate for a quantum bit (qubit) in a solid state implementation of a quantum computer. In particular, the mechanisms responsible for decoherence are examined in a variety of Si/SiGe quantum wells, and it is seen that their behavior does not correspond to published theories of decoherence in these structures. Transport data are analyzed for all samples to determine the electrical properties of each, taking into account a parallel conduction path seen in all samples. Furthermore, the effect of confining the electrons into nanostructures of varying size in one of the samples is studied. All but one of the samples examined are grown by ultrahigh vacuum chemical vapor deposition at the University of Wisconsin - Madison. The nanostructures are patterned on a sample provided by IBM using the Nabity Pattern Generation Software (NPGS) on a LEO1530 Scanning Electron Microscope, and etched using SF6 in an STS reactive ion etcher. Continuous-wave electron spin resonance studies are done using a Bruker ESP300E spectrometer, with a 4.2K continuous flow cryostat and X-band cavity. In order to fully characterize the sample, electrical measurements were done. Hall bars are etched into the 2DEGs, and Ohmic contacts are annealed in to provide a current path through the 2DEG. Measurements are made both from room temperature down to 2K in a Physical Property Measurement System (PPMS), and at 300mK using a custom built probe in a one shot 3He cryostat made by Oxford Instruments. The custom built probe also allows high frequency excitations, facilitating electrically detected magnetic resonance (EDMR) experiments. In many of the samples, an orientationally dependent electron spin resonance linewidth is seen whose anisotropy is much larger at small angles than that predicted by

  20. Synthesis and Characterization of Chemically Etched Nanostructured Silicon

    KAUST Repository

    Mughal, Asad Jahangir

    2012-05-01

    Silicon is an essential element in today’s modern world. Nanostructured Si is a more recently studied variant, which has currently garnered much attention. When its spatial dimensions are confined below a certain limit, its optical properties change dramatically. It transforms from an indirect bandgap material that does not absorb or emit light efficiently into one which can emit visible light at room temperatures. Although much work has been conducted in understanding the properties of nanostructured Si, in particular porous Si surfaces, a clear understanding of the origin of photoluminescence has not yet been produced. Typical synthesis approaches used to produce nanostructured Si, in particular porous Si and nanocrystalline Si have involved complex preparations used at high temperatures, pressures, or currents. The purpose of this thesis is to develop an easier synthesis approach to produce nanostructured Si as well as arrive at a clearer understanding of the origin of photoluminescence in these systems. We used a simple chemical etching technique followed by sonication to produce nanostructured Si suspensions. The etching process involved producing pores on the surface of a Si substrate in a solution containing hydrofluoric acid and an oxidant. Nanocrystalline Si as well as nanoscale amorphous porous Si suspensions were successfully synthesized using this process. We probed into the phase, composition, and origin of photoluminescence in these materials, through the use of several characterization techniques. TEM and SEM were used to determine morphology and phase. FT-IR and XPS were employed to study chemical compositions, and steady state and time resolved optical spectroscopy techniques were applied to resolve their photoluminescent properties. Our work has revealed that the type of oxidant utilized during etching had a significant impact on the final product. When using nitric acid as the oxidant, we formed nanocrystalline Si suspensions composed of

  1. Silicon nanostructures in silicon oxynitride for PV application: effect of argon

    Energy Technology Data Exchange (ETDEWEB)

    Ehrhardt, Fabien; Ferblantier, Gerald; Muller, Dominique; Slaoui, Abdelilah [Institut d' Electronique du Solide et des Systemes, UMR CNRS-UdS 7163, 23 Rue du Loess, BP20, 67034 Strasbourg cedex 2 (France); Ulhaq-Bouillet, Corinne [Institut de Physique et Chimie des Materiaux de Strasbourg, UMR CNRS-UdS 7504, 23 Rue du Loess, BP43, 67034 Strasbourg cedex 2 (France)

    2012-10-15

    Silicon rich silicon oxynitride (SRSON) were deposited by ECR-PECVD to form silicon nanostructures. The effect of argon flow during the deposition was investigated. The silicon nanoparticles were fabricated by a classical thermal treatment of SRSON films. The structural properties of the SRSON films were investigated by RBS and FTIR measurements. We show that the silicon excess in the SiO{sub x}N{sub y} matrix changes slightly with Ar flow but it has a significant impact on the silicon nanoparticles morphology embedded in the silicon oxynitride layer. Different shapes for silicon nanostructures ranging from separated Si nanocrystals to Si nanocolumns were formed as studied by energy-filtred transmission electron microscopy analysis (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Investigation of the phase formation from nickel coated nanostructured silicon

    Science.gov (United States)

    Shilyaeva, Yulia I.; Pyatilova, Olga V.; Berezkina, Alexandra Yu.; Sysa, Artem V.; Dudin, Alexander A.; Smirnov, Dmitry I.; Gavrilov, Sergey A.

    2016-12-01

    In this paper, the influence of the conditions of chemical and electrochemical nickel plating of nanostructured silicon and subsequent heat treatment on the phase composition of Si/Ni structures with advanced interface is studied. Nanostructured silicon formed by chemical and electrochemical etching was used for the formation of a developed interphase surface. The resulting Si/Ni samples were analyzed using scanning electron microscopy, energy dispersive X-ray analysis, and X-ray phase analysis. The experiments have revealed the differences in phase composition of the Si/Ni structures obtained by different methods, both before and after heat treatment.

  3. Electroluminescence from Silicon and Germanium Nanostructures

    African Journals Online (AJOL)

    quantum confinement model (QCM), that can explain PL and EL on pure Si nanostructures and Si-terminated with impurities. Keywords: Quantum confinement, Nanostructure, Exciton binding energy,. Electroluminescence. INTRODUCTION. It has been realized that the integration of optoelectronic components on all Si ...

  4. Hydrogen isotopic substitution experiments in nanostructured porous silicon

    International Nuclear Information System (INIS)

    Palacios, W.D.; Koropecki, R.R.; Arce, R.D.; Busso, A.

    2008-01-01

    Nanostructured porous silicon is usually prepared by electrochemical anodization of monocrystalline silicon using a fluorine-rich electrolyte. As a result of this process, the silicon atoms conserve their original crystalline location, and many of the dangling bonds appearing on the surface of the nanostructure are saturated by hydrogen coming from the electrolyte. This work presents an IR study of the effects produced by partial substitution of water in the electrolytic solution by deuterium oxide. The isotopic effects on the IR spectra are analyzed for the as-prepared samples and for the samples subjected to partial thermal effusion of hydrogen and deuterium. We demonstrate that, although deuterium is chemically indistinguishable from hydrogen, it presents a singular behaviour when used in porous silicon preparation. We found that deuterium preferentially bonds forming Si-DH groups. A possible explanation of the phenomenon is presented, based on the different diffusivities of hydrogen and deuterium

  5. Hydrogen isotopic substitution experiments in nanostructured porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, W.D. [Facultad de Ciencias Exactas y Naturales y Agrimensura - (UNNE), Avenida Libertad 5500, 3400 Corrientes (Argentina); Koropecki, R.R. [INTEC (CONICET-UNL), Gueemes 3450, 3000 Santa Fe (Argentina)], E-mail: rkoro@intec.ceride.gov.ar; Arce, R.D. [INTEC (CONICET-UNL), Gueemes 3450, 3000 Santa Fe (Argentina); Busso, A. [Facultad de Ciencias Exactas y Naturales y Agrimensura - (UNNE), Avenida Libertad 5500, 3400 Corrientes (Argentina)

    2008-04-30

    Nanostructured porous silicon is usually prepared by electrochemical anodization of monocrystalline silicon using a fluorine-rich electrolyte. As a result of this process, the silicon atoms conserve their original crystalline location, and many of the dangling bonds appearing on the surface of the nanostructure are saturated by hydrogen coming from the electrolyte. This work presents an IR study of the effects produced by partial substitution of water in the electrolytic solution by deuterium oxide. The isotopic effects on the IR spectra are analyzed for the as-prepared samples and for the samples subjected to partial thermal effusion of hydrogen and deuterium. We demonstrate that, although deuterium is chemically indistinguishable from hydrogen, it presents a singular behaviour when used in porous silicon preparation. We found that deuterium preferentially bonds forming Si-DH groups. A possible explanation of the phenomenon is presented, based on the different diffusivities of hydrogen and deuterium.

  6. Passivating electron contact based on highly crystalline nanostructured silicon oxide layers for silicon solar cells

    Czech Academy of Sciences Publication Activity Database

    Stuckelberger, J.; Nogay, G.; Wyss, P.; Jeangros, Q.; Allebe, Ch.; Debrot, F.; Niquille, X.; Ledinský, Martin; Fejfar, Antonín; Despeisse, M.; Haug, F.J.; Löper, P.; Ballif, C.

    2016-01-01

    Roč. 158, Dec (2016), s. 2-10 ISSN 0927-0248 R&D Projects: GA MŠk LM2015087 Institutional support: RVO:68378271 Keywords : surface passivation * passivating contact * nanostructure * silicon oxide * nanocrystalline * microcrystalline * poly-silicon * crystallization * Raman * transmission line measurement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.784, year: 2016

  7. Rapid Solid-State Metathesis Routes to Nanostructured Silicon-Germainum

    Science.gov (United States)

    Kaner, Richard B. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor); Rodriguez, Marc (Inventor)

    2014-01-01

    Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

  8. Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices

    OpenAIRE

    Schriver, Maria Christine

    2012-01-01

    A novel solar cell architecture made completely from the earth abundant elements silicon and carbon has been developed. Hydrogenated amorphous silicon (aSi:H), rather than crystalline silicon, is used as the active material due to its high absorption through a direct band gap of 1.7eV, well matched to the solar spectrum to ensure the possibility of improved cells in this architecture with higher efficiencies. The cells employ a Schottky barrier design wherein the amorphous silicon absorber la...

  9. Silicon nanostructures produced by laser direct etching

    DEFF Research Database (Denmark)

    Müllenborn, Matthias; Dirac, Paul Andreas Holger; Petersen, Jon Wulff

    1995-01-01

    A laser direct-write process has been applied to structure silicon on a nanometer scale. In this process, a silicon substrate, placed in a chlorine ambience, is locally heated above its melting point by a continuous-wave laser and translated by high-resolution direct-current motor stages. Only...... the molten silicon reacts spontaneously with the molecular chlorine, resulting in trenches with the width of the laser-generated melt. Trenches have been etched with a width of less than 70 nm. To explain the functional dependence of the melt size on absorbed power, the calculations based on a two...

  10. Electroluminescence from Silicon and Germanium Nanostructures ...

    African Journals Online (AJOL)

    The EL and PL intensities occurs at the same energy; however, the EL intensity has sharp Gaussian sub peaks and red shifted compared to the PL intensity. To get our result, we used the idea of quantum confinement model (QCM), that can explain PL and EL on pure Si nanostructures and Si-terminated with impurities.

  11. Nanostructured sp2-carbon infiltration of mesoporous silicon layers.

    Science.gov (United States)

    Polini, Riccardo; Valentini, Veronica; Mattei, Giorgio

    2009-06-01

    The preparation of composite layers made of porous silicon (PS) infiltrated with nanostructured carbon is reported. These composite layers were obtained by chemical vapor infiltration (CVI) of mesoporous silicon under process conditions normally employed to grow diamond films by Hot Filament Chemical Vapour Deposition (HFCVD). Micro-Raman spectroscopy and Field Emission Gun Scanning Electron Microscopy (FEG-SEM) techniques showed that diamond nucleation density was very low whilst sp2 carbon permeated completely, even after 1 h deposition, the thickness of the PS layers that preserved their mesoporous columnar structure.

  12. Computational modeling of geometry dependent phonon transport in silicon nanostructures

    Science.gov (United States)

    Cheney, Drew A.

    Recent experiments have demonstrated that thermal properties of semiconductor nanostructures depend on nanostructure boundary geometry. Phonons are quantized mechanical vibrations that are the dominant carrier of heat in semiconductor materials and their aggregate behavior determine a nanostructure's thermal performance. Phonon-geometry scattering processes as well as waveguiding effects which result from coherent phonon interference are responsible for the shape dependence of thermal transport in these systems. Nanoscale phonon-geometry interactions provide a mechanism by which nanostructure geometry may be used to create materials with targeted thermal properties. However, the ability to manipulate material thermal properties via controlling nanostructure geometry is contingent upon first obtaining increased theoretical understanding of fundamental geometry induced phonon scattering processes and having robust analytical and computational models capable of exploring the nanostructure design space, simulating the phonon scattering events, and linking the behavior of individual phonon modes to overall thermal behavior. The overall goal of this research is to predict and analyze the effect of nanostructure geometry on thermal transport. To this end, a harmonic lattice-dynamics based atomistic computational modeling tool was created to calculate phonon spectra and modal phonon transmission coefficients in geometrically irregular nanostructures. The computational tool is used to evaluate the accuracy and regimes of applicability of alternative computational techniques based upon continuum elastic wave theory. The model is also used to investigate phonon transmission and thermal conductance in diameter modulated silicon nanowires. Motivated by the complexity of the transmission results, a simplified model based upon long wavelength beam theory was derived and helps explain geometry induced phonon scattering of low frequency nanowire phonon modes.

  13. Nanostructured silicon anodes for lithium ion rechargeable batteries.

    Science.gov (United States)

    Teki, Ranganath; Datta, Moni K; Krishnan, Rahul; Parker, Thomas C; Lu, Toh-Ming; Kumta, Prashant N; Koratkar, Nikhil

    2009-10-01

    Rechargeable lithium ion batteries are integral to today's information-rich, mobile society. Currently they are one of the most popular types of battery used in portable electronics because of their high energy density and flexible design. Despite their increasing use at the present time, there is great continued commercial interest in developing new and improved electrode materials for lithium ion batteries that would lead to dramatically higher energy capacity and longer cycle life. Silicon is one of the most promising anode materials because it has the highest known theoretical charge capacity and is the second most abundant element on earth. However, silicon anodes have limited applications because of the huge volume change associated with the insertion and extraction of lithium. This causes cracking and pulverization of the anode, which leads to a loss of electrical contact and eventual fading of capacity. Nanostructured silicon anodes, as compared to the previously tested silicon film anodes, can help overcome the above issues. As arrays of silicon nanowires or nanorods, which help accommodate the volume changes, or as nanoscale compliant layers, which increase the stress resilience of silicon films, nanoengineered silicon anodes show potential to enable a new generation of lithium ion batteries with significantly higher reversible charge capacity and longer cycle life.

  14. Ordered silicon nanostructures for silicon-based photonics devices

    Czech Academy of Sciences Publication Activity Database

    Fojtík, A.; Valenta, J.; Pelant, Ivan; Kálal, M.; Fiala, P.

    2007-01-01

    Roč. 5, Suppl. (2007), S250-S253 ISSN 1671-7694 R&D Projects: GA AV ČR IAA1010316 Grant - others:GA MŠk(CZ) ME 933 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystals * silicon * self-assembled monolayers Subject RIV: BM - Solid Matter Physics ; Magnetism

  15. Silicone cushions for engineering applications

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    When a complex system composed of materials of very different properties is subjected to varying temperature, differential thermal expansion and contraction will produce intolerable stresses unless the parts are separated by suitable cushions. In addition to accommodating differential thermal expansion and contraction, these cushions must absorb shock and vibration, take up dimensional tolerances in the parts, and distribute and attenuate applied loads. We are studying cellular silicone cushions, starting with raw materials and polymer manufacture, to analysis of mechanical and chemical properties, through short- and long-term life testing, in order to tailor cushions to various specific engineering requirements

  16. Engineering piezoresistivity using biaxially strained silicon

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads

    2008-01-01

    of the piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity...

  17. Harnessing no-photon exciton generation chemistry to engineer semiconductor nanostructures.

    Science.gov (United States)

    Beke, David; Károlyházy, Gyula; Czigány, Zsolt; Bortel, Gábor; Kamarás, Katalin; Gali, Adam

    2017-09-06

    Production of semiconductor nanostructures with high yield and tight control of shape and size distribution is an immediate quest in diverse areas of science and technology. Electroless wet chemical etching or stain etching can produce semiconductor nanoparticles with high yield but is limited to a few materials because of the lack of understanding the physical-chemical processes behind. Here we report a no-photon exciton generation chemistry (NPEGEC) process, playing a key role in stain etching of semiconductors. We demonstrate NPEGEC on silicon carbide polymorphs as model materials. Specifically, size control of cubic silicon carbide nanoparticles of diameter below ten nanometers was achieved by engineering hexagonal inclusions in microcrystalline cubic silicon carbide. Our finding provides a recipe to engineer patterned semiconductor nanostructures for a broad class of materials.

  18. Nanostructuration with visible-light-emitting silicon nanocrystals

    CERN Document Server

    Huisken, F; Ledoux, G; Hofmeister, H; Cichos, F; Martín, J

    2003-01-01

    Silicon nanocrystals with diameters between 2.5 and 7 nm were prepared by CO sub 2 laser pyrolysis of silane in a gas flow reactor. A small portion of the particles created in the reaction zone was extracted as a molecular beam through a conical nozzle and deposited at low energy on substrates. Placing suitable masks in front of the substrate, micro- and nanostructured films were obtained. The patterned structures were characterized by atomic force microscopy and transmission electron microscopy while their optical properties were studied by laser scanning confocal microscopy. Nanostructures as small as 30 nm could be produced. The photoluminescence emanating from a regular array of 1.2 mu m sized dots composed of Si nanocrystals was studied with spatial, spectral and temporal resolution.

  19. Ion induced segregation in gold nanostructured thin films on silicon

    International Nuclear Information System (INIS)

    Ghatak, J.; Satyam, P.V.

    2008-01-01

    We report a direct observation of segregation of gold atoms to the near surface regime due to 1.5 MeV Au 2+ ion impact on isolated gold nanostructures deposited on silicon. Irradiation at fluences of 6 x 10 13 , 1 x 10 14 and 5 x 10 14 ions cm -2 at a high beam flux of 6.3 x 10 12 ions cm -2 s -1 show a maximum transported distance of gold atoms into the silicon substrate to be 60, 45 and 23 nm, respectively. At a lower fluence (6 x 10 13 ions cm -2 ) transport has been found to be associated with the formation of gold silicide (Au 5 Si 2 ). At a high fluence value of 5 x 10 14 ions cm -2 , disassociation of gold silicide and out-diffusion lead to the segregation of gold to defect - rich surface and interface regions.

  20. Nanostructured Porous Silicon Photonic Crystal for Applications in the Infrared

    Directory of Open Access Journals (Sweden)

    G. Recio-Sánchez

    2012-01-01

    Full Text Available In the last decades great interest has been devoted to photonic crystals aiming at the creation of novel devices which can control light propagation. In the present work, two-dimensional (2D and three-dimensional (3D devices based on nanostructured porous silicon have been fabricated. 2D devices consist of a square mesh of 2 μm wide porous silicon veins, leaving 5×5 μm square air holes. 3D structures share the same design although multilayer porous silicon veins are used instead, providing an additional degree of modulation. These devices are fabricated from porous silicon single layers (for 2D structures or multilayers (for 3D structures, opening air holes in them by means of 1 KeV argon ion bombardment through the appropriate copper grids. For 2D structures, a complete photonic band gap for TE polarization is found in the thermal infrared range. For 3D structures, there are no complete band gaps, although several new partial gaps do exist in different high-symmetry directions. The simulation results suggest that these structures are very promising candidates for the development of low-cost photonic devices for their use in the thermal infrared range.

  1. Nanostructured porous silicon by laser assisted electrochemical etching

    Science.gov (United States)

    Li, J.; Lu, C.; Hu, X. K.; Yang, Xiujuan; Loboda, A. V.; Lipson, R. H.

    2009-08-01

    Nanostructured porous silicon (pSi) was fabricated by combining electrochemical etching with 355 nm laser processing. pSi prepared in this way proves to be an excellent substrate for desorption/ionization on silicon (DIOS) mass spectrometry (MS). Surfaces prepared by electrochemical etching and laser irradiation exhibit strong quantum confinement as evidenced by the observation of a red shift in the Si Raman band at ~520-500 cm-1. The height of the nanostructured columns produced by electrochemical etching and laser processing is on the order of microns compared with tens of nanometers obtained without laser irradiation. The threshold for laser desorption and ionization of 12 mJ/cm2 using the pSi substrates prepared in this work is lower than that obtained for conventional matrix assisted laser desorption ionization (MALDI)-MS using a standard matrix compound such as [alpha]-cyano-4-hydroxycinnamic acid (CHCA; 30 mJ/cm2). Furthermore, the substrates prepared by etching and laser irradiation appear to resist laser damage better than those prepared by etching alone. These results enhance the capability of pSi for the detection of small molecular weight analytes by DIOS-MS.

  2. Reflectance analysis of porosity gradient in nanostructured silicon layers

    Science.gov (United States)

    Jurečka, Stanislav; Imamura, Kentaro; Matsumoto, Taketoshi; Kobayashi, Hikaru

    2017-12-01

    In this work we study optical properties of nanostructured layers formed on silicon surface. Nanostructured layers on Si are formed in order to reach high suppression of the light reflectance. Low spectral reflectance is important for improvement of the conversion efficiency of solar cells and for other optoelectronic applications. Effective method of forming nanostructured layers with ultralow reflectance in a broad interval of wavelengths is in our approach based on metal assisted etching of Si. Si surface immersed in HF and H2O2 solution is etched in contact with the Pt mesh roller and the structure of the mesh is transferred on the etched surface. During this etching procedure the layer density evolves gradually and the spectral reflectance decreases exponentially with the depth in porous layer. We analyzed properties of the layer porosity by incorporating the porosity gradient into construction of the layer spectral reflectance theoretical model. Analyzed layer is splitted into 20 sublayers in our approach. Complex dielectric function in each sublayer is computed by using Bruggeman effective media theory and the theoretical spectral reflectance of modelled multilayer system is computed by using Abeles matrix formalism. Porosity gradient is extracted from the theoretical reflectance model optimized in comparison to the experimental values. Resulting values of the structure porosity development provide important information for optimization of the technological treatment operations.

  3. Protein Design for Nanostructural Engineering: General Aspects.

    Science.gov (United States)

    Grove, Tijana Z; Cortajarena, Aitziber L

    2016-01-01

    This chapter aims to introduce the main challenges in the field of protein design for engineering of nanostructures and functional materials. First, we introduce proteins and illustrate the key characteristics that open many possibilities for the use of proteins in nanotechnology. Then, we describe the current state of the art of nanopatterning techniques and the actual needs of the emerging field of nanotechnology to develop new tools in order to achieve precise control and manipulation of elements at the nanoscale. In this sense, the increasing knowledge of protein science and advances in protein design allow to tackle current challenges such as the design of nanodevices, nanopatterned surfaces, and nanomachines. This book highlights the recent progresses of protein nanotechnology over the last decade and emphasizes the power of protein engineering through illustrative examples of protein based-assemblies and their potential applications.

  4. Nanostructured silicon nitride from wheat and rice husks

    Science.gov (United States)

    Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Wollmershauser, J. A.; Feng, C. R.

    2016-04-01

    Nanoparticles, submicron-diameter tubes, and rods of Si3N4 were synthesized from the thermal treatment of wheat and rice husks at temperatures at and above 1300 °C in a nitrogen atmosphere. The whole pattern Rietveld analysis of the observed diffraction data from treatments at 1300 °C showed the formation of only hexagonal α-phase of Si3N4 with an R-factor of 1%, whereas samples treated at 1400 °C and above showed both α- and β-phases with an R-factor of 2%. Transmission electron microscopy showed the presence of tubes, rods, and nanoparticles of Si3N4. In a two-step process, where pure SiC was produced first from rice or wheat husk in an argon atmosphere and subsequently treated in a nitrogen atmosphere at 1450 °C, a nanostructured composite material having α- and β-phases of Si3N4 combined with cubic phase of SiC was formed. The thermodynamics of the formation of silicon nitride is discussed in terms of the solid state reaction between organic matter (silica content), which is inherently present in the wheat and rice husks, with the nitrogen from the furnace atmosphere. Nanostructures of silicon nitride formed by a single direct reaction or their composites with SiC formed in a two-step process of agricultural byproducts provide an uncomplicated sustainable synthesis route for silicon nitride used in mechanical, biotechnology, and electro-optic nanotechnology applications.

  5. Terahertz response of DNA oligonucleotides on the surface of silicon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, N. T., E-mail: bagraev@mail.ioffe.ru [Peter the Great Saint-Petersburg Polytechnic University (Russian Federation); Chernev, A. L. [Russian Academy of Sciences, Saint Petersburg Academic University—Nanotechnology Research and Education Center (Russian Federation); Klyachkin, L. E.; Malyarenko, A. M. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Emel’yanov, A. K.; Dubina, M. V. [Russian Academy of Sciences, Saint Petersburg Academic University—Nanotechnology Research and Education Center (Russian Federation)

    2016-09-15

    The possibility of identifying DNA oligonucleotides deposited onto the region of the edge channels of silicon nanostructures is considered. The role of various THz (terahertz) radiation harmonics of silicon nanostructures in the resonance response of oligonucleotides is analyzed. In particular, this makes it possible to compare single-stranded 100- and 50-mer DNA oligonucleotides. A technique for the rapid identification of different oligonucleotides by measuring changes in the conductance and transverse potential difference of silicon nanostructures with microcavities, embedded in the edge channels for selecting THz radiation characteristics, is proposed.

  6. Distribution patterns of different carbon nanostructures in silicon nitride composites.

    Science.gov (United States)

    Tapasztó, Orsolya; Markó, Márton; Balázsi, Csaba

    2012-11-01

    The dispersion properties of single- and multi-walled carbon nanotubes as well as mechanically exfoliated few layer graphene flakes within the silicon nitride ceramic matrix have been investigated. Small angle neutron scattering experiments have been employed to gain information on the dispersion of the nano-scale carbon fillers throughout the entire volume of the samples. The neutron scattering data combined with scanning electron microscopy revealed strikingly different distribution patterns for different types of carbon nanostructures. The scattering intensities for single wall carbon nanotubes (SWCNTs) reveal a decay exponent characteristic to surface fractals, which indicate that the predominant part of nanotubes can be found in loose networks wrapping the grains of the polycrystalline matrix. By contrast, multi wall carbon nanotubes (MWCNTs) were found to be present mainly in the form of bulk aggregate structures, while few-layer graphene (FLG) flakes have been individually dispersed within the host matrix, under the very same preparation and processing conditions.

  7. Polarization dependent nanostructuring of silicon with femtosecond vortex pulse

    Directory of Open Access Journals (Sweden)

    M. G. Rahimian

    2017-08-01

    Full Text Available We fabricated conical nanostructures on silicon with a tip dimension of ∼ 70 nm using a single twisted femtosecond light pulse carrying orbital angular momentum (ℓ=±1. The height of the nano-cone, encircled by a smooth rim, increased from ∼ 350 nm to ∼ 1 μm with the pulse energy and number of pulses, whereas the apex angle remained constant. The nano-cone height was independent of the helicity of the twisted light; however, it is reduced for linear polarization compared to circular at higher pulse energies. Fluid dynamics simulations show nano-cones formation when compressive forces arising from the radial inward motion of the molten material push it perpendicular to the surface and undergo re-solidification. Simultaneously, the radial outward motion of the molten material re-solidifies after reaching the cold boundary to form a rim. Overlapping of two irradiated spots conforms to the fluid dynamics model.

  8. Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes

    Directory of Open Access Journals (Sweden)

    Thomas Baumgärtel

    2013-03-01

    Full Text Available This study investigates the controlled chemical functionalization of silicon oxide nanostructures prepared by AFM-anodization lithography of alkyl-terminated silicon. Different conditions for the growth of covalently bound mono-, multi- or submonolayers of distinctively functional silane molecules on nanostructures have been identified by AFM-height investigations. Routes for the preparation of methyl- or amino-terminated structures or silicon surfaces are presented and discussed. The formation of silane monolayers on nanoscopic silicon oxide nanostructures was found to be much more sensitive towards ambient humidity than, e.g., the silanization of larger OH-terminated silica surfaces. Amino-functionalized nanostructures have been successfully modified by the covalent binding of functional fluorescein dye molecules. Upon excitation, the dye-functionalized structures show only weak fluorescence, which may be an indication of a relatively low surface coverage of the dye molecules on length scale that is not accessible by standard AFM measurements.

  9. Lifetime of ALD Al2O3 Passivated Black Silicon Nanostructured for Photovoltaic Applications

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    .5%. For passivation purposes we used 37 nm ALD Al2O3 films and conducted lifetime measurements and found 1220 µs and to 4170 µs, respectively, for p- and n-type CZ silicon wafers. Such results are promising results to introduce for black silicon RIE nano-structuring in solar cell process flow....

  10. Metallic nanostructure formation limited by the surface hydrogen on silicon.

    Science.gov (United States)

    Perrine, Kathryn A; Teplyakov, Andrew V

    2010-08-03

    Constant miniaturization of electronic devices and interfaces needed to make them functional requires an understanding of the initial stages of metal growth at the molecular level. The use of metal-organic precursors for metal deposition allows for some control of the deposition process, but the ligands of these precursor molecules often pose substantial contamination problems. One of the ways to alleviate the contamination problem with common copper deposition precursors, such as copper(I) (hexafluoroacetylacetonato) vinyltrimethylsilane, Cu(hfac)VTMS, is a gas-phase reduction with molecular hydrogen. Here we present an alternative method to copper film and nanostructure growth using the well-defined silicon surface. Nearly ideal hydrogen termination of silicon single-crystalline substrates achievable by modern surface modification methods provides a limited supply of a reducing agent at the surface during the initial stages of metal deposition. Spectroscopic evidence shows that the Cu(hfac) fragment is present upon room-temperature adsorption and reacts with H-terminated Si(100) and Si(111) surfaces to deposit metallic copper. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to follow the initial stages of copper nucleation and the formation of copper nanoparticles, and X-ray energy dispersive spectroscopy (XEDS) confirms the presence of hfac fragments on the surfaces of nanoparticles. As the surface hydrogen is consumed, copper nanoparticles are formed; however, this growth stops as the accessible hydrogen is reacted away at room temperature. This reaction sets a reference for using other solid substrates that can act as reducing agents in nanoparticle growth and metal deposition.

  11. Graphene directed architecture of fine engineered nanostructures with electrochemical applications

    DEFF Research Database (Denmark)

    Hou, Chengyi; Zhang, Minwei; Halder, Arnab

    2017-01-01

    . In this review, we aim to highlight some recent efforts devoted to rational design, assembly and fine engineering of electrochemically active nanostructures using graphene or/and its derivatives as soft templates for controlled synthesis and directed growth. We organize the contents according to the chemically...... classified nanostructures, including metallic nanostructures, self-assembled organic and supramolecular structures, and fine engineered metal oxides. In these cases, graphene templates either sacrificed during templating synthesis or retained as support for final products. We also discuss remained challenges...... and future perspective in the graphene-templating design and synthesis of various materials. Overall, this review could offer crucial insights into the nanoscale engineering of new nanostructures using graphene as a soft template and their potential applications in electrochemical science and technology. We...

  12. Effects of nanostructurized silicon on proliferation of stem and cancer cell.

    Science.gov (United States)

    Osminkina, L A; Luckyanova, E N; Gongalsky, M B; Kudryavtsev, A A; Gaydarova, A Kh; Poltavtseva, R A; Kashkarov, P K; Timoshenko, V Yu; Sukhikh, G T

    2011-05-01

    In vitro experiments showed that stem and cancer cells retained their viability on the surface of porous silicon with 10-100 nm nanostructures, but their proliferation was inhibited. Silicon nanoparticles of 100 nm in size obtained by mechanical grinding of porous silicon films or crystal silicon plates in a concentration below 1 mg/ml in solution did not modify viability and proliferation of mouse fibroblast and human laryngeal cancer cells. Additional ultrasonic exposure of cancer cells in the presence of 1 mg/ml silicon nanoparticles added to nutrient medium led to complete destruction of cells or to the appearance of membrane defects blocking their proliferation and initiating their apoptotic death.

  13. Nanostructured silicon carbon thin films grown by plasma enhanced chemical vapour deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Coscia, U. [Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); CNISM Unita' di Napoli, Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); Ambrosone, G., E-mail: ambrosone@na.infn.it [Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); SPIN-CNR, Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); Basa, D.K. [Department of Physics, Utkal University, Bhubaneswar 751004 (India); Rigato, V. [INFN Laboratori Nazionali Legnaro, 35020 Legnaro (Padova) (Italy); Ferrero, S.; Virga, A. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2013-09-30

    Nanostructured silicon carbon thin films, composed of Si nanocrystallites embedded in hydrogenated amorphous silicon carbon matrix, have been prepared by varying rf power in ultra high vacuum plasma enhanced chemical vapour deposition system using silane and methane gas mixtures diluted in hydrogen. In this paper we have studied the compositional, structural and electrical properties of these films as a function of rf power. It is shown that with increasing rf power the atomic densities of carbon and hydrogen increase while the atomic density of silicon decreases, resulting in a reduction in the mass density. Further, it is demonstrated that carbon is incorporated into amorphous matrix and it is mainly bonded to silicon. The study has also revealed that the crystalline volume fraction decreases with increase in rf power and that the films deposited with low rf power have a size distribution of large and small crystallites while the films deposited with relatively high power have only small crystallites. Finally, the enhanced transport properties of the nanostructured silicon carbon films, as compared to amorphous counterpart, have been attributed to the presence of Si nanocrystallites. - Highlights: • The mass density of silicon carbon films decreases from 2.3 to 2 g/cm{sup 3}. • Carbon is incorporated in the amorphous phase and it is mainly bonded to silicon. • Nanostructured silicon carbon films are deposited at rf power > 40 W. • Si nanocrystallites in amorphous silicon carbon enhance the electrical properties.

  14. Characterization of perovskite layer on various nanostructured silicon wafer

    Science.gov (United States)

    Rostan, Nur Fairuz Mohd; Sepeai, Suhaila; Ramli, Noor Fadhilah; Azhari, Ayu Wazira; Ludin, Norasikin Ahmad; Teridi, Mohd Asri Mat; Ibrahim, Mohd Adib; Zaidi, Saleem H.

    2017-05-01

    Crystalline silicon (c-Si) solar cell dominates 90% of photovoltaic (PV) market. The c-Si is the most mature of all PV technologies and expected to remain leading the PV technology by 2050. The attractive characters of Si solar cell are stability, long lasting and higher lifetime. Presently, the efficiency of c-Si solar cell is still stuck at 25% for one and half decades. Tandem approach is one of the attempts to improve the Si solar cell efficiency with higher bandgap layer is stacked on top of Si bottom cell. Perovskite offers a big potential to be inserted into a tandem solar cell. Perovskite with bandgap of 1.6 to 1.9 eV will be able to absorb high energy photons, meanwhile c-Si with bandgap of 1.124 eV will absorb low energy photons. The high carrier mobility, high carrier lifetime, highly compatible with both solution and evaporation techniques makes perovskite an eligible candidate for perovskite-Si tandem configuration. The solution of methyl ammonium lead iodide (MAPbI3) was prepared by single step precursor process. The perovskite layer was deposited on different c-Si surface structure, namely planar, textured and Si nanowires (SiNWs) by using spin-coating technique at different rotation speeds. The nanostructure of Si surface was textured using alkaline based wet chemical etching process and SiNW was grown using metal assisted etching technique. The detailed surface morphology and absorbance of perovskite were studied in this paper. The results show that the thicknesses of MAPbI3 were reduced with the increasing of rotation speed. In addition, the perovskite layer deposited on the nanostructured Si wafer became rougher as the etching time and rotation speed increased. The average surface roughness increased from ˜24 nm to ˜38 nm for etching time range between 5-60 min at constant low rotation speed (2000 rpm) for SiNWs Si wafer.

  15. Silicon-germanium and platinum silicide nanostructures for silicon based photonics

    Science.gov (United States)

    Storozhevykh, M. S.; Dubkov, V. P.; Arapkina, L. V.; Chizh, K. V.; Mironov, S. A.; Chapnin, V. A.; Yuryev, V. A.

    2017-05-01

    This paper reports a study of two types of silicon based nanostructures prospective for applications in photonics. The first ones are Ge/Si(001) structures forming at room temperature and reconstructing after annealing at 600°C. Germanium, being deposited from a molecular beam at room temperature on the Si(001) surface, forms a thin granular film composed of Ge particles with sizes of a few nanometers. A characteristic feature of these films is that they demonstrate signs of the 2 x 1 structure in their RHEED patterns. After short-term annealing at 600°C under the closed system conditions, the granular films reconstruct to heterostructures consisting of a Ge wetting layer and oval clusters of Ge. A mixed type c(4x2) + p(2x2) reconstruction typical to the low-temperature MBE (Tgr class of materials is one of the friendliest to silicon technology. But as silicide film thickness reaches a few nanometers, low resistivity becomes of primary importance. Pt3Si has the lowest sheet resistance among the Pt silicides. However, the development of a process of thin Pt3Si films formation is a challenging task. This paper describes formation of a thin Pt3Si/Pt2Si structures at room temperature on poly-Si films. Special attention is paid upon formation of poly-Si and amorphous Si films on Si3N4 substrates at low temperatures.

  16. Spherical plasmoids formed upon the combustion and explosion of nanostructured hydrated silicon

    Science.gov (United States)

    Lazarouk, S. K.; Dolbik, A. V.; Labunov, V. A.; Borisenko, V. E.

    2007-02-01

    The kinetics of the combustion and explosion of nanostructured hydrated porous silicon has been analyzed in a duration range from 100 μs to 1 s. It has been shown that the presence of hydrogen in silicon nanostructures increases the energy yield of oxidation processes leading to the formation of spherical plasmoids with a size of 0.1-0.8 m. Buoyancy in them can be compensated by the weight of the material particles formed inside and this compensation leads to a change in the velocity of plasmoids from 0.5 m/s to zero in the process of their cooling. It is hypothesized that a ball lightning appears due to the combustion and explosion of nanostructured hydrated silicon in spherical plasmoids.

  17. Dysprosium disilicide nanostructures on silicon(001) studied by scanning tunneling microscopy and transmission electron microscopy

    International Nuclear Information System (INIS)

    Ye Gangfeng; Nogami, Jun; Crimp, Martin A.

    2006-01-01

    The microstructure of self-assembled dysprosium silicide nanostructures on silicon(001) has been studied by scanning tunneling microscopy and transmission electron microscopy. The studies focused on nanostructures that involve multiple atomic layers of the silicide. Cross-sectional high resolution transmission electron microscopy images and fast Fourier transform analysis showed that both hexagonal and orthorhombic/tetragonal silicide phases were present. Both the magnitude and the anisotropy of lattice mismatch between the silicide and the substrate play roles in the morphology and epitaxial growth of the nanostructures formed

  18. Mg-catalyzed autoclave synthesis of aligned silicon carbide nanostructures.

    Science.gov (United States)

    Xi, Guangcheng; Liu, Yankuan; Liu, Xiaoyan; Wang, Xiaoqing; Qian, Yitai

    2006-07-27

    In this article, a novel magnesium-catalyzed co-reduction route was developed for the large-scale synthesis of aligned beta-SiC one-dimensional (1D) nanostructures at relative lower temperature (600 degrees C). By carefully controlling the reagent concentrations, we could synthesize beta-SiC rodlike and needlelike nanostructures. The possible growth mechanism of the as-synthesized beta-SiC 1D nanostructures has been investigated. The structure and morphology of the as-synthesized beta-SiC nanostructures are characterized using X-ray diffraction, Fourier transform infrared absorption, and scanning and transmission electron microscopes. Raman and photoluminescence properties are also investigated at room temperature. The as-synthesized beta-SiC nanostructures exhibit strong shape-dependent field emission properties. Corresponding to their shapes, the as-synthesized nanorods and nanoneedles display the turn-on fields of 12, 8.4, and 1.8 V/microm, respectively.

  19. Towards Ordered Silicon Nanostructures through Self-Assembling Mechanisms and Processes

    Directory of Open Access Journals (Sweden)

    R. A. Puglisi

    2015-01-01

    Full Text Available The design and development of innovative architectures for memory storage and energy conversion devices are at the forefront of current research efforts driving us towards a sustainable future. However, issues related to the cost, efficiency, and reliability of current technologies are still severely limiting their overtake of the standard designs. The use of ordered nanostructured silicon is expected to overcome these limitations and push the advancement of the alternative technologies. Specifically, self-assembling of block copolymers has been recognized as a promising and cost-effective approach to organize silicon nanostructures. This work reviews some of the most important findings on block copolymer self-assembling and complements those with the results of new experimental studies. First of all, a quantitative analysis is presented on the ordering and fluctuations expected in the synthesis of silicon nanostructures by using standard synthesis methods like chemical vapour deposition. Then the effects of the several parameters guiding the ordering mechanisms in the block copolymer systems, such as film thickness, molecular weight, annealing conditions, solvent, and substrate topography are discussed. Finally, as a proof of concept, an in-house developed example application to solar cells is presented, based on silicon nanostructures resulting from self-assembling of block copolymers.

  20. Thermal conductivity engineering in width-modulated silicon nanowires and thermoelectric efficiency enhancement

    Science.gov (United States)

    Zianni, Xanthippi

    2018-03-01

    Width-modulated nanowires have been proposed as efficient thermoelectric materials. Here, the electron and phonon transport properties and the thermoelectric efficiency are discussed for dimensions above the quantum confinement regime. The thermal conductivity decreases dramatically in the presence of thin constrictions due to their ballistic thermal resistance. It shows a scaling behavior upon the width-modulation rate that allows for thermal conductivity engineering. The electron conductivity also decreases due to enhanced boundary scattering by the constrictions. The effect of boundary scattering is weaker for electrons than for phonons and the overall thermoelectric efficiency is enhanced. A ZT enhancement by a factor of 20-30 is predicted for width-modulated nanowires compared to bulk silicon. Our findings indicate that width-modulated nanostructures are promising for developing silicon nanostructures with high thermoelectric efficiency.

  1. White light emission from engineered silicon carbide

    DEFF Research Database (Denmark)

    Ou, Haiyan

    Silicon carbide (SiC) is a wide indirect bandgap semiconductor. The light emission efficiency is low in nature. But this material has very unique physical properties like good thermal conductivity, high break down field etc in addition to its abundance. Therefore it is interesting to engineer its...... light emission property so that to take fully potential applications of this material. In this talk, two methods, i.e. doping SiC heavily by donor-acceptor pairs and making SiC porous are introduced to make light emission from SiC. By co-doping SiC with nitrogen and boron heavily, strong yellow emission...

  2. Physics and engineering of peptide supramolecular nanostructures.

    Science.gov (United States)

    Handelman, Amir; Beker, Peter; Amdursky, Nadav; Rosenman, Gil

    2012-05-14

    The emerging "bottom-up" nanotechnology reveals a new field of bioinspired nanomaterials composed of chemically synthesized biomolecules. They are formed from elementary constituents in supramolecular structures by the use of a developed nature self-assembly mechanism. The focus of this perspective paper is on intrinsic fundamental physical properties of bioinspired peptide nanostructures and their small building units linked by weak noncovalent bonds. The observed exceptional optical properties indicate a phenomenon of quantum confinement in these supramolecular structures, which originates from nanoscale size of their elementary building blocks. The dimensionality of the confinement gives insight into intrinsic packing of peptide supramolecular nanomaterials. QC regions, revealed in bioinspired nanostructures, were found by us in amyloid fibrils formed from insulin protein. We describe ferroelectric and related properties found at the nanoscale based on original crystalline asymmetry of the nanoscale building blocks, packing these structures. In this context, we reveal a classic solid state physics phenomenon such as reconstructive phase transition observed in bioorganic peptide nanotubes. This irreversible phase transformation leads to drastic reshaping of their quantum structure from quantum dots to quantum wells, which is followed by variation of their space group symmetry from asymmetric to symmetric. We show that the supramolecular origin of these bioinspired nanomaterials provides them a unique chance to be disassembled into elementary building block peptide nanodots of 1-2 nm size possessing unique electronic, optical and ferroelectric properties. These multifunctional nanounits could lead to a new future step in nanotechnology and nanoscale advanced devices in the fields of nanophotonics, nanobiomedicine, nanobiopiezotronics, etc. This journal is © the Owner Societies 2012

  3. The effect of electrospun nanofibers alignment on the synthesis of one-dimensional silicon carbide nanostructure

    Science.gov (United States)

    Hooshyar, Ali; Kokabi, Mehrdad

    2018-01-01

    One-dimensional silicon carbide (1D SiC) nanostructure has shown unusual properties such as extremely high strength, good flexibility, fracture toughness, wide band gap ( 3.2eV), large breakdown electric field strength (>2 MV cm-1, 10 times that of silicon), and inverse Hall-Petch effect. Because of these advantages, 1D SiC nanomaterial has gained extensive attention on the wide range of applications in microelectronics, optoelectronics, nanocomposites, and catalyst supports. Many methods have been used for the synthesis of 1D SiC nanostructures such as chemical vapor deposition, carbon nanotube-confined reaction, laser ablation, high-frequency induction heating, and arc discharge. However, these methods have also some shortcomings such as using catalyst, high-cost, low yield, irregular geometry and impurity. In this work, electrospinning was used to prepare aligned PVA/SiO2 composite nanofibers and the effect of fiber alignment on the production efficiency and quality of 1D SiC nanostructure was investigated. For this purpose, aligned electrospun nanofibers, as the desirable precursor, were put in a tube furnace and heated up to 1250°C under a controlled program in an inert atmosphere. Finally, the grown 1D SiC nanostructure product was characterized using SEM, XRD, and FTIR. The results confirmed the successful synthesis of pure crystalline1D β-SiC nanostructure with high yield, more regular, and metal catalyst-free.

  4. Angle resolved characterization of nanostructured and conventionally textured silicon solar cells

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Ormstrup, Jeppe; Ommen, Martin Lind

    2015-01-01

    current, open circuit voltage, fill factor (FF) and power conversion efficiency are each measured as function of the relative incident angle between the solar cell and the light source. The relative incident angle is varied from 0° to 90° in steps of 10° in orthogonal axes, such that each solar cell......We report angle resolved characterization of nanostructured and conventionally textured silicon solar cells. The nanostructured solar cells are realized through a single step, mask-less, scalable reactive ion etching (RIE) texturing of the surface. Photovoltaic properties including short circuit...

  5. Nanostructured Biomaterials for Tissue Engineered Bone Tissue Reconstruction

    Directory of Open Access Journals (Sweden)

    Bressan Eriberto

    2012-01-01

    Full Text Available Bone tissue engineering strategies are emerging as attractive alternatives to autografts and allografts in bone tissue reconstruction, in particular thanks to their association with nanotechnologies. Nanostructured biomaterials, indeed, mimic the extracellular matrix (ECM of the natural bone, creating an artificial microenvironment that promotes cell adhesion, proliferation and differentiation. At the same time, the possibility to easily isolate mesenchymal stem cells (MSCs from different adult tissues together with their multi-lineage differentiation potential makes them an interesting tool in the field of bone tissue engineering. This review gives an overview of the most promising nanostructured biomaterials, used alone or in combination with MSCs, which could in future be employed as bone substitutes. Recent works indicate that composite scaffolds made of ceramics/metals or ceramics/polymers are undoubtedly more effective than the single counterparts in terms of osteoconductivity, osteogenicity and osteoinductivity. A better understanding of the interactions between MSCs and nanostructured biomaterials will surely contribute to the progress of bone tissue engineering.

  6. Electron-phonon scattering effect on the lattice thermal conductivity of silicon nanostructures.

    Science.gov (United States)

    Fu, Bo; Tang, Guihua; Li, Yifei

    2017-11-01

    Nanostructuring technology has been widely employed to reduce the thermal conductivity of thermoelectric materials because of the strong phonon-boundary scattering. Optimizing the carrier concentration can not only improve the electrical properties, but also affect the lattice thermal conductivity significantly due to the electron-phonon scattering. The lattice thermal conductivity of silicon nanostructures considering electron-phonon scattering is investigated for comparing the lattice thermal conductivity reductions resulting from nanostructuring technology and the carrier concentration optimization. We performed frequency-dependent simulations of thermal transport systematically in nanowires, solid thin films and nanoporous thin films by solving the phonon Boltzmann transport equation using the discrete ordinate method. All the phonon properties are based on the first-principles calculations. The results show that the lattice thermal conductivity reduction due to the electron-phonon scattering decreases as the feature size of nanostructures goes down and could be ignored at low feature sizes (50 nm for n-type nanowires and 20 nm for p-type nanowires and n-type solid thin films) or a high porosity (0.6 for n-type 500 nm-thick nanoporous thin films) even when the carrier concentration is as high as 10 21 cm -3 . Similarly, the size effect due to the phonon-boundary scattering also becomes less significant with the increase of carrier concentration. The findings provide a fundamental understanding of electron and phonon transports in nanostructures, which is important for the optimization of nanostructured thermoelectric materials.

  7. Nanostructured silicon-based biosensors for the selective identification of analytes of social interest

    International Nuclear Information System (INIS)

    D'Auria, Sabato; Champdore, Marcella de; Aurilia, Vincenzo; Parracino, Antonietta; Staiano, Maria; Vitale, Annalisa; Rossi, Mose; Rea, Ilaria; Rotiroti, Lucia; Rossi, Andrea M; Borini, Stefano; Rendina, Ivo; Stefano, Luca De

    2006-01-01

    Small analytes such as glucose, L-glutamine (Gln), and ammonium nitrate are detected by means of optical biosensors based on a very common nanostructured material, porous silicon (PSi). Specific recognition elements, such as protein receptors and enzymes, were immobilized on hydrogenated PSi wafers and used as probes in optical sensing systems. The binding events were optically transduced as wavelength shifts of the porous silicon reflectivity spectrum or were monitored via changes of the fluorescence emission. The biosensors described in this article suggest a general approach for the development of new sensing systems for a wide range of analytes of high social interest

  8. ZnO Nanostructures for Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Marco Laurenti

    2017-11-01

    Full Text Available This review focuses on the most recent applications of zinc oxide (ZnO nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair.

  9. Silicon photonic crystal nanostructures for refractive index sensing

    DEFF Research Database (Denmark)

    Dorfner, Dominic; Hürlimann, T.; Zabel, T.

    2008-01-01

    The authors present the fabrication and optical investigation of Silicon on Insulator photonic crystal drop-filters for use as refractive index sensors. Two types of defect nanocavities (L3 and H1-r) are embedded between two W1 photonic crystal waveguides to evanescently route light at the cavity...

  10. Estimation of oxide related electron trap energy of porous silicon nanostructures

    International Nuclear Information System (INIS)

    Das, Mainak Mohan; Ray, Mallar; Bandyopadhyay, Nil Ratan; Hossain, Syed Minhaz

    2010-01-01

    Estimation of electron trap energy (E t ), with respect to bulk Si valence band, of oxidized porous silicon (PS) nanostructures is reported. Photoluminescence (PL) spectra of oxidized PS prepared with different formation parameters have been investigated and the room temperature PL characteristics have been successfully explained on the basis of oxide related trap assisted transitions. PL peak energy for the oxidized samples with low porosity exhibited a blue shift with increasing formation current density (J). For the high porosity samples double peaks appeared in the PL spectra. One of these peaks remained constant at ∼730 nm while the other was blue shifted with increase in J. Evolution of PS nanostructure was correlated to the formation parameters using a simple growth mechanism. PS nanostructure was modelled as an array of regular hexagonal pores and the average value of E t was estimated to be 1.67 eV.

  11. Synergistically Enhanced Performance of Ultrathin Nanostructured Silicon Solar Cells Embedded in Plasmonically Assisted, Multispectral Luminescent Waveguides.

    Science.gov (United States)

    Lee, Sung-Min; Dhar, Purnim; Chen, Huandong; Montenegro, Angelo; Liaw, Lauren; Kang, Dongseok; Gai, Boju; Benderskii, Alexander V; Yoon, Jongseung

    2017-04-25

    Ultrathin silicon solar cells fabricated by anisotropic wet chemical etching of single-crystalline wafer materials represent an attractive materials platform that could provide many advantages for realizing high-performance, low-cost photovoltaics. However, their intrinsically limited photovoltaic performance arising from insufficient absorption of low-energy photons demands careful design of light management to maximize the efficiency and preserve the cost-effectiveness of solar cells. Herein we present an integrated flexible solar module of ultrathin, nanostructured silicon solar cells capable of simultaneously exploiting spectral upconversion and downshifting in conjunction with multispectral luminescent waveguides and a nanostructured plasmonic reflector to compensate for their weak optical absorption and enhance their performance. The 8 μm-thick silicon solar cells incorporating a hexagonally periodic nanostructured surface relief are surface-embedded in layered multispectral luminescent media containing organic dyes and NaYF 4 :Yb 3+ ,Er 3+ nanocrystals as downshifting and upconverting luminophores, respectively, via printing-enabled deterministic materials assembly. The ultrathin nanostructured silicon microcells in the composite luminescent waveguide exhibit strongly augmented photocurrent (∼40.1 mA/cm 2 ) and energy conversion efficiency (∼12.8%) than devices with only a single type of luminescent species, owing to the synergistic contributions from optical downshifting, plasmonically enhanced upconversion, and waveguided photon flux for optical concentration, where the short-circuit current density increased by ∼13.6 mA/cm 2 compared with microcells in a nonluminescent medium on a plain silver reflector under a confined illumination.

  12. Study of the technology of the plasma nanostructuring of silicon to form highly efficient emission structures

    Energy Technology Data Exchange (ETDEWEB)

    Galperin, V. A.; Kitsyuk, E. P. [“Technological Center” Research-and-Production Company (Russian Federation); Pavlov, A. A. [Russian Academy of Sciences, Institute of Nanotechnologies in Microelectronics (Russian Federation); Shamanaev, A. A., E-mail: artemiy.shamanaev@tcen.ru [“Technological Center” Research-and-Production Company (Russian Federation)

    2015-12-15

    New methods for silicon nanostructuring and the possibility of raising the aspect ratios of the structures being formed are considered. It is shown that the technology developed relates to self-formation methods and is an efficient tool for improving the quality of field-emission cathodes based on carbon nanotubes (CNTs) by increasing the Si–CNT contact area and raising the efficiency of the heat sink.

  13. Silicon vacancy-related centers in non-irradiated 6H-SiC nanostructur

    Czech Academy of Sciences Publication Activity Database

    Bagraev, N.T.; Danilovskii, E.Yu.; Gets, D.S.; Kalabukhova, E.N.; Klyachkin, L.E.; Koudryavtsev, A.A.; Malyarenko, A.M.; Mashkov, V.A.; Savchenko, Dariia; Shanina, B.D.

    2015-01-01

    Roč. 49, č. 5 (2015), 649-657 ISSN 1063-7826 R&D Projects: GA ČR GP13-06697P; GA MŠk(CZ) LM2011029 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : electron spin resonance * 6H-SiC nanostructures * silicon vacancy related centers * NV centers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.701, year: 2015

  14. Thermal Conductivity Suppression in Nanostructured Silicon and Germanium Nanowires

    Science.gov (United States)

    Özden, Ayberk; Kandemir, Ali; Ay, Feridun; Perkgöz, Nihan Kosku; Sevik, Cem

    2016-03-01

    The inherent low lattice thermal conductivity (TC) of semiconductor nanowires (s-NW) due to one-dimensional phonon confinement might provide a solution for the long-lasting figure-of-merit problem for highly efficient thermoelectric (TE) applications. Standalone diameter modulation or alloying of s-NW serve as a toolkit for TC control, but realizing the full potential of nanowires requires new atomic-scale designs, growth, characterization, and understanding of the physical mechanisms behind the structure-property (TC) relationship. Before undertaking time-consuming and expensive experimental work, molecular dynamics (MD) simulations serve as an excellent probe to investigate new designs and understand how nanostructures affect thermal transport properties through their capability to capture various phenomena such as phonon boundary scattering, phonon coherence resonance, and phonon backscattering. On the other hand, because different research groups use different structural and MD parameters in their simulations, it is rather difficult to make comparisons between different nanostructures and select appropriate ones for potential TE applications. Therefore, in this work, we systematically investigated pristine, core-shell (C-S), holey (H-N), superlattice (SL), sawtooth (ST), and superlattice sawtooth (SL-ST) nanowires with identical structural parameters. Specifically, we aim to compare the relative TC reduction achieved by these nanostructures with respect to pristine nanowires in order to propose the best structural design with the lowest lattice TC, using Green-Kubo method-based equilibrium molecular dynamics simulations at 300 K. Our results show that the TC can be minimized by changing specific parameters such as the core diameter and monolayer separation for C-S, H-N, and ST structures. In the case of SL structures, the TC is found to be independent of these parameters. However, surface roughness in the form of a ST morphology provides a TC value below 2 W

  15. Fabrication of TiO2 nanostructures on porous silicon for thermoelectric application

    Science.gov (United States)

    Fahrizal, F. N.; Ahmad, M. K.; Ramli, N. M.; Ahmad, N.; Fakhriah, R.; Mohamad, F.; Nafarizal, N.; Soon, C. F.; Ameruddin, A. S.; Faridah, A. B.; Shimomura, M.; Murakami, K.

    2017-09-01

    Nowadays, technology is moving by leaps and bounds over the last several decades. This has created new opportunities and challenge in the research fields. In this study, the experiment is about to investigate the potential of Titanium Dioxide (TiO2) nanostructures that have been growth onto a layer of porous silicon (pSi) for their thermoelectric application. Basically, it is divided into two parts, which is the preparation of the porous silicon (pSi) substrate by electrochemical-etching process and the growth of the Titanium Dioxide (TiO2) nanostructures by hydrothermal method. This sample have been characterize by Field Emission Scanning Electron Microscopy (FESEM) to visualize the morphology of the TiO2 nanostructures area that formed onto the porous silicon (pSi) substrate. Besides, the sample is also used to visualize their cross-section images under the FESEM microscopy. Next, the sample is characterized by the X-Ray Diffraction (XRD) machine. The XRD machine is used to get the information about the chemical composition, crystallographic structure and physical properties of materials.

  16. Effective Chemical Route to 2D Nanostructured Silicon Electrode Material: Phase Transition from Exfoliated Clay Nanosheet to Porous Si Nanoplate

    International Nuclear Information System (INIS)

    Adpakpang, Kanyaporn; Patil, Sharad B.; Oh, Seung Mi; Kang, Joo-Hee; Lacroix, Marc; Hwang, Seong-Ju

    2016-01-01

    Graphical abstract: Effective morphological control of porous silicon 2D nanoplate can be achieved by the magnesiothermically-induced phase transition of exfoliated silicate clay nanosheets. The promising lithium storage performance of the obtained silicon materials with huge capacity and excellent rate characteristics underscores the prime importance of porously 2D nanostructured morphology of silicon. - Highlights: • 2D nanostructured silicon electrode materials are successfully synthesized via the magnesiothermically-induced phase transition of exfoliated clay 2D nanosheets. • High discharge capacity and rate capability are achieved from the 2D nanoplates of silicon. • Silicon 2D nanoplates can enhance both Li + diffusion and charge-transfer kinetics. • 2D nanostructured silicon is beneficial for the cycling stability by minimizing the volume change during lithiation-delithiation. - Abstract: An efficient and economical route for the synthesis of porous two-dimensional (2D) nanoplates of silicon is developed via the magnesiothermically-induced phase transition of exfoliated clay 2D nanosheets. The magnesiothermic reaction of precursor clay nanosheets prepared by the exfoliation and restacking with Mg 2+ cations yields porous 2D nanoplates of elemental silicon. The variation in the Mg:SiO 2 ratio has a significant effect on the porosity and connectivity of silicon nanoplates. The porous silicon nanoplates show a high discharge capacity of 2000 mAh g −1 after 50 cycles. Of prime importance is that this electrode material still retains a large discharge capacity at higher C-rates, which is unusual for the elemental silicon electrode. This is mainly attributed to the improved diffusion of lithium ions, charge-transfer kinetics, and the preservation of the electrical connection of the porous 2D plate-shaped morphology. This study highlights the usefulness of clay mineral as an economical and scalable precursor of high-performance silicon electrodes with

  17. Ultrafast photoluminescence dynamics of blue-emitting silicon nanostructures

    Czech Academy of Sciences Publication Activity Database

    Žídek, K.; Trojánek, F.; Malý, P.; Pelant, Ivan; Gilliot, P.; Hönerlange, B.

    2011-01-01

    Roč. 8, č. 3 (2011), s. 979-984 ISSN 1862-6351 R&D Projects: GA AV ČR(CZ) IAA101120804; GA MŠk LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : silicon * nanocrystals * time-resolved spectroscopy * luminescence * polarization * two-photon absorption Subject RIV: BM - Solid Matter Physics ; Magnetism http://onlinelibrary.wiley.com/doi/10.1002/pssc.201000394/abstract

  18. Interfacial Engineering of Silicon Carbide Nanowire/Cellulose Microcrystal Paper toward High Thermal Conductivity.

    Science.gov (United States)

    Yao, Yimin; Zeng, Xiaoliang; Pan, Guiran; Sun, Jiajia; Hu, Jiantao; Huang, Yun; Sun, Rong; Xu, Jian-Bin; Wong, Ching-Ping

    2016-11-16

    Polymer composites with high thermal conductivity have attracted much attention, along with the rapid development of electronic devices toward higher speed and better performance. However, high interfacial thermal resistance between fillers and matrix or between fillers and fillers has been one of the primary bottlenecks for the effective thermal conduction in polymer composites. Herein, we report on engineering interfacial structure of silicon carbide nanowire/cellulose microcrystal paper by generating silver nanostructures. We show that silver nanoparticle-deposited silicon carbide nanowires as fillers can effectively enhance the thermal conductivity of the matrix. The in-plane thermal conductivity of the resultant composite paper reaches as high as 34.0 W/m K, which is one order magnitude higher than that of conventional polymer composites. Fitting the measured thermal conductivity with theoretical models qualitatively demonstrates that silver nanoparticles bring the lower interfacial thermal resistances both at silicon carbide nanowire/cellulose microcrystal and silicon carbide nanowire/silicon carbide nanowire interfaces. This interfacial engineering approach provides a powerful tool for sophisticated fabrication of high-performance thermal-management materials.

  19. Ab initio design of nanostructures for solar energy conversion: a case study on silicon nitride nanowire.

    Science.gov (United States)

    Pan, Hui

    2014-01-01

    Design of novel materials for efficient solar energy conversion is critical to the development of green energy technology. In this work, we present a first-principles study on the design of nanostructures for solar energy harvesting on the basis of the density functional theory. We show that the indirect band structure of bulk silicon nitride is transferred to direct bandgap in nanowire. We find that intermediate bands can be created by doping, leading to enhancement of sunlight absorption. We further show that codoping not only reduces the bandgap and introduces intermediate bands but also enhances the solubility of dopants in silicon nitride nanowires due to reduced formation energy of substitution. Importantly, the codoped nanowire is ferromagnetic, leading to the improvement of carrier mobility. The silicon nitride nanowires with direct bandgap, intermediate bands, and ferromagnetism may be applicable to solar energy harvesting.

  20. Electrically-detected ESR in silicon nanostructures inserted in microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, Nikolay; Danilovskii, Eduard; Gets, Dmitrii; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna [Ioffe Physical Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); Gehlhoff, Wolfgang [Technische Universitaet Berlin, D-10623, Berlin (Germany); Mashkov, Vladimir; Romanov, Vladimir [Petersburg State Polytechnical University, Polytekhnicheskaya 29, 195251 St. Petersburg (Russian Federation)

    2014-02-21

    We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ- barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance, with internal GHz Josephson emission within frameworks of the normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane.

  1. ODMR of single point defects in silicon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, Nikolay; Danilovsky, Eduard; Gets, Dmitry; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna [Ioffe Physical-Technical Institute, Polytekhnicheskaya st. 26, 194021 St. Petersburg (Russian Federation)

    2012-05-15

    We present the findings of the optically detected magnetic resonance technique (ODMR), which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor {delta}-barriers. This technique allows the ODMR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the transmission spectra within the frameworks of the excitonic normal-mode coupling caused by the microcavities embedded in the Si-QW plane. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Suspended HOPG nanosheets for HOPG nanoresonator engineering and new carbon nanostructure synthesis

    International Nuclear Information System (INIS)

    Rose, F; Debray, A; Martin, P; Fujita, H; Kawakatsu, H

    2006-01-01

    Suspended highly oriented pyrolytic graphite (HOPG) nanosheets (10-300 nm thick) were created by direct mechanical cleavage of a bulk HOPG crystal onto silicon micropillars and microtracks. We show that suspended HOPG nanosheets can be used to engineer HOPG nanoresonators such as membranes, bridges, and cantilevers as thin as 28 carbon atom layers. We measured by Doppler laser heterodyne interferometry that the discrete vibration modes of an HOPG nanosheet membrane and the resonance frequency of a FIB-created HOPG microcantilever lie in the MHz frequency regime. Moreover, a new carbon nanostructure, named 'nanolace', was synthesized by focused ion beam (FIB) sputtering of suspended HOPG nanosheets. Graphite nanosheets suspended on micropillars were eroded by a FIB to create self-oriented pseudo-periodical ripples. Additional sputtering and subsequent milling of these ripples led to the formation of honeycomb-like shaped nanolaces suspended and linked by ribbons

  3. Engineered Nanostructured MEA Technology for Low Temperature Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yimin

    2009-07-16

    The objective of this project is to develop a novel catalyst support technology based on unique engineered nanostructures for low temperature fuel cells which: (1) Achieves high catalyst activity and performance; (2) Improves catalyst durability over current technologies; and (3) Reduces catalyst cost. This project is directed at the development of durable catalysts supported by novel support that improves the catalyst utilization and hence reduce the catalyst loading. This project will develop a solid fundamental knowledge base necessary for the synthetic effort while at the same time demonstrating the catalyst advantages in Direct Methanol Fuel Cells (DMFCs).

  4. Thermal conductivity anisotropy in holey silicon nanostructures and its impact on thermoelectric cooling

    Science.gov (United States)

    Ren, Zongqing; Lee, Jaeho

    2018-01-01

    Artificial nanostructures have improved prospects of thermoelectric systems by enabling selective scattering of phonons and demonstrating significant thermal conductivity reductions. While the low thermal conductivity provides necessary temperature gradients for thermoelectric conversion, the heat generation is detrimental to electronic systems where high thermal conductivity are preferred. The contrasting needs of thermal conductivity are evident in thermoelectric cooling systems, which call for a fundamental breakthrough. Here we show a silicon nanostructure with vertically etched holes, or holey silicon, uniquely combines the low thermal conductivity in the in-plane direction and the high thermal conductivity in the cross-plane direction, and that the anisotropy is ideal for lateral thermoelectric cooling. The low in-plane thermal conductivity due to substantial phonon boundary scattering in small necks sustains large temperature gradients for lateral Peltier junctions. The high cross-plane thermal conductivity due to persistent long-wavelength phonons effectively dissipates heat from a hot spot to the on-chip cooling system. Our scaling analysis based on spectral phonon properties captures the anisotropic size effects in holey silicon and predicts the thermal conductivity anisotropy ratio up to 20. Our numerical simulations demonstrate the thermoelectric cooling effectiveness of holey silicon is at least 30% greater than that of high-thermal-conductivity bulk silicon and 400% greater than that of low-thermal-conductivity chalcogenides; these results contrast with the conventional perception preferring either high or low thermal conductivity materials. The thermal conductivity anisotropy is even more favorable in laterally confined systems and will provide effective thermal management solutions for advanced electronics.

  5. Thermal conductivity anisotropy in holey silicon nanostructures and its impact on thermoelectric cooling.

    Science.gov (United States)

    Ren, Zongqing; Lee, Jaeho

    2018-01-26

    Artificial nanostructures have improved prospects of thermoelectric systems by enabling selective scattering of phonons and demonstrating significant thermal conductivity reductions. While the low thermal conductivity provides necessary temperature gradients for thermoelectric conversion, the heat generation is detrimental to electronic systems where high thermal conductivity are preferred. The contrasting needs of thermal conductivity are evident in thermoelectric cooling systems, which call for a fundamental breakthrough. Here we show a silicon nanostructure with vertically etched holes, or holey silicon, uniquely combines the low thermal conductivity in the in-plane direction and the high thermal conductivity in the cross-plane direction, and that the anisotropy is ideal for lateral thermoelectric cooling. The low in-plane thermal conductivity due to substantial phonon boundary scattering in small necks sustains large temperature gradients for lateral Peltier junctions. The high cross-plane thermal conductivity due to persistent long-wavelength phonons effectively dissipates heat from a hot spot to the on-chip cooling system. Our scaling analysis based on spectral phonon properties captures the anisotropic size effects in holey silicon and predicts the thermal conductivity anisotropy ratio up to 20. Our numerical simulations demonstrate the thermoelectric cooling effectiveness of holey silicon is at least 30% greater than that of high-thermal-conductivity bulk silicon and 400% greater than that of low-thermal-conductivity chalcogenides; these results contrast with the conventional perception preferring either high or low thermal conductivity materials. The thermal conductivity anisotropy is even more favorable in laterally confined systems and will provide effective thermal management solutions for advanced electronics.

  6. Self-organized nanostructures in silicon and glass for MEMS, MOEMS and BioMEMS

    International Nuclear Information System (INIS)

    Lilienthal, K.; Fischer, M.; Stubenrauch, M.; Schober, A.

    2010-01-01

    The utilization of self-organization in the process workflows for Micro-Electro-Mechanical-Systems (MEMS) and their derivatives is a smart way to get large areas of nanostructured surfaces for various applications. The generation of nano-masking spots by self-organizing residues in the plasma can lead to needle- or tube-like structures on the surface after (deep-) reactive ion etching. With lengths of 3 up to 25 μm and 150 up to 500 nm in diameter for silicon broad applications in the fields of micro fluidics with catalysts, micro-optical or mechanical mountings or carrier wafer bonding in microelectronics are possible. Now, we also developed dry etching processes for fused silica which shows analogue properties to 'Black Silicon' and investigated these glass nanostructures by a first parameter study to identify new usable structures and hybrids. This innovative starting point allows the transfer of 'Black Silicon' technologies and its applications to another important material class in micro- and nanotechnologies, fused silica.

  7. Optimization of the optical properties of nanostructured silicon surfaces for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Di; Pennec, Y.; Djafari-Rouhani, B.; Lambert, Y.; Deblock, Y.; Stiévenard, D., E-mail: didier.stievenard@isen.fr [Institut d' Electronique et de Microélectronique et de Nanotechnologies, IEMN, (CNRS, UMR 8520), Groupe de Physique, Cité scientifique, avenue Poincaré, 59652 Villeneuve d' Ascq (France); Cristini-Robbe, O. [PHLAM, UMR8523, Université de Lille 1, 59652 Villeneuve d' Asq Cedex (France); Xu, T. [Key Laboratory of Advanced Display and System Application, Shanghai University, 149 Yanchang Road, Shanghai 200072 (China); Faucher, M. [Institut d' Electronique et de Microélectronique et de Nanotechnologies, IEMN, (CNRS, UMR 8520), Groupe NAM6, Cité scientifique, avenue Poincaré, 59652 Villeneuve d' Asq (France)

    2014-04-07

    Surface nanostructuration is an important challenge for the optimization of light trapping in solar cell. We present simulations on both the optical properties and the efficiency of micro pillars—MPs—or nanocones—NCs—silicon based solar cells together with measurements on their associated optical absorption. We address the simulation using the Finite Difference Time Domain method, well-adapted to deal with a periodic set of nanostructures. We study the effect of the period, the bottom diameter, the top diameter, and the height of the MPs or NCs on the efficiency, assuming that one absorbed photon induces one exciton. This allows us to give a kind of abacus involving all the geometrical parameters of the nanostructured surface with regard to the efficiency of the associated solar cell. We also show that for a given ratio of the diameter over the period, the best efficiency is obtained for small diameters. For small lengths, MPs are extended to NCs by changing the angle between the bottom surface and the vertical face of the MPs. The best efficiency is obtained for an angle of the order of 70°. Finally, nanostructures have been processed and allow comparing experimental results with simulations. In every case, a good agreement is found.

  8. Optimization of the optical properties of nanostructured silicon surfaces for solar cell applications

    Science.gov (United States)

    Zhou, Di; Pennec, Y.; Djafari-Rouhani, B.; Cristini-Robbe, O.; Xu, T.; Lambert, Y.; Deblock, Y.; Faucher, M.; Stiévenard, D.

    2014-04-01

    Surface nanostructuration is an important challenge for the optimization of light trapping in solar cell. We present simulations on both the optical properties and the efficiency of micro pillars—MPs—or nanocones—NCs—silicon based solar cells together with measurements on their associated optical absorption. We address the simulation using the Finite Difference Time Domain method, well-adapted to deal with a periodic set of nanostructures. We study the effect of the period, the bottom diameter, the top diameter, and the height of the MPs or NCs on the efficiency, assuming that one absorbed photon induces one exciton. This allows us to give a kind of abacus involving all the geometrical parameters of the nanostructured surface with regard to the efficiency of the associated solar cell. We also show that for a given ratio of the diameter over the period, the best efficiency is obtained for small diameters. For small lengths, MPs are extended to NCs by changing the angle between the bottom surface and the vertical face of the MPs. The best efficiency is obtained for an angle of the order of 70°. Finally, nanostructures have been processed and allow comparing experimental results with simulations. In every case, a good agreement is found.

  9. EDESR of impurity centers in nanostructures inserted in silicon microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, Nikolay; Danilovsky, Eduard; Gets, Dmitry; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna [Ioffe Physical-Technical Institute, Polytekhnicheskaya st. 26, 194021 St. Petersburg (Russian Federation); Gehlhoff, Wolfgang [Institut fuer Festkoerperphysik, TU Berlin, 10623 Berlin (Germany); Mashkov, Vladimir; Romanov, Vladimir [State Polytechnical University, 195251 St. Petersburg (Russian Federation)

    2012-05-15

    We present the first findings of the new electrically detected electron spin resonance technique (EDESR) which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor {delta}-barriers. This technique allows the ESR identification without the application of the external cavity as well as the high frequency (hf) source and recorder, with measuring the only magnetoresistance caused by the hf emission from the {delta}-barriers in the presence of the microcavity embedded in the Si-QW plane. The new resonant positive magnetoresistance data are interpreted here in terms of the interference transition in the diffusive transport of free holes respectively between the weak antilocalization regime in the range of magnetic fields far from the ESR of a paramagnetic point defect located inside or near the conductive channel and the weak localization regime in the range of magnetic fields corresponding to the ESR of that defect. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Engineering functionalized multi-phased silicon/silicon oxide nano-biomaterials to passivate the aggressive proliferation of cancer

    Science.gov (United States)

    Premnath, P.; Tan, B.; Venkatakrishnan, K.

    2015-01-01

    Currently, the use of nano silicon in cancer therapy is limited as drug delivery vehicles and markers in imaging, not as manipulative/controlling agents. This is due to limited properties that native states of nano silicon and silicon oxides offers. We introduce nano-functionalized multi-phased silicon/silicon oxide biomaterials synthesized via ultrashort pulsed laser synthesis, with tunable properties that possess inherent cancer controlling properties that can passivate the progression of cancer. This nanostructured biomaterial is composed of individual functionalized nanoparticles made of a homogenous hybrid of multiple phases of silicon and silicon oxide in increasing concentration outwards from the core. The chemical properties of the proposed nanostructure such as number of phases, composition of phases and crystal orientation of each functionalized nanoparticle in the three dimensional nanostructure is defined based on precisely tuned ultrashort pulsed laser-material interaction mechanisms. The amorphous rich phased biomaterial shows a 30 fold (95%) reduction in number of cancer cells compared to bulk silicon in 48 hours. Further, the size of the cancer cells reduces by 76% from 24 to 48 hours. This method exposes untapped properties of combination of multiple phases of silicon oxides and its applications in cancer therapy. PMID:26190009

  11. Improvement of Infrared Detectors for Tissue Oximetry using Black Silicon Nanostructures

    DEFF Research Database (Denmark)

    Petersen, Søren Dahl; Davidsen, Rasmus Schmidt; Alcala, Lucia R.

    2014-01-01

    We present a nanostructured surface, made of dry etched black silicon, which lowers the reflectance for light incident at all angles. This surface is fabricated on infrared detectors used for tissue oximetry, where the detection of weak diffuse light signals is important. Monte Carlo simulations...... performed on a model of a neonatal head shows that approximately 60% of the injected light will be diffuse reflected. However, the change in diffuse reflected light due to the change in cerebral oxygenation is very low and the light will be completely isotropic scattered. The reflectance of the black...... in quantum efficiency for both normal incident light and light incident at 38°....

  12. PDMS-on-silicon microsystems: Integration of polymer micro/nanostructures for new MEMS device functions

    Science.gov (United States)

    Tung, Yi-Chung

    2005-11-01

    Modern technologies found in military, space-craft, automotive, and telecommunications applications strongly demand reductions of the manufacturing cost, power consumption, size, and weight of integrated sensors and actuators. The research field of microelectromechanical systems (MEMS) has seen significant technological innovations and advancements to meet this demand in the last two decades. Historically, MEMS technology has been seen as an offspring of silicon-based integrated circuit (IC) technology. But recently, the roles that polymer materials play in MEMS have been more pronounced due to their cost effectiveness, manufacturability, and compatibility with micro/nanoscale biological and chemical systems. Among these polymers, an organic elastomer, Polydimethylsiloxane (PDMS), has become one of the most popular materials because of its unique material properties and moldability suited for low-cost rapid prototyping based on a fabrication technique called soft lithography. However, PDMS micro/nanostructures, not allowed to be integrated with other silicon-based devices, find their limited use in MEMS other than in passive microfluidic components. The lack of a technology bridging the gap between silicon and PDMS prohibits us to realize new MEMS devices potentially resulting from the simultaneous use of these two materials. This research explores a fully new technological concept of "PDMS-on-silicon microsystems." "PDMS-on-silicon microsystems" refers to a class of novel MEMS devices integrating PDMS micro/nanostructures onto silicon actuators and/or sensors. The research aims to demonstrate a new type of MEMS devices taking advantage of benefits resulting from both of silicon and PDMS. To achieve this goal, this work develops a new MEMS fabrication technique called "soft-lithographic lift-off and grafting (SLLOG)." The SLLOG process starts with soft lithography-based molding and release of a three-dimensional (3D) PDMS microstructure. This is followed by

  13. Enhanced light absorption in an ultrathin silicon solar cell utilizing plasmonic nanostructures

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Mortensen, N. Asger

    2012-01-01

    Nowadays, bringing photovoltaics to the market is mainly limited by high cost of electricity produced by the photovoltaic solar cell. Thin-film photovoltaics offers the potential for a significant cost reduction compared to traditional photovoltaics. However, the performance of thin-film solar...... cells is generally limited by poor light absorption. We propose an ultrathin-film silicon solar cell configuration based on SOI structure, where the light absorption is enhanced by use of plasmonic nanostructures. By placing a one-dimensional plasmonic nanograting on the bottom of the solar cell......, the generated photocurrent for a 200 nm-thickness crystalline silicon solar cell can be enhanced by 90% in the considered wavelength range. These results are paving a promising way for the realization of high-efficiency thin-film solar cells....

  14. Engineering aperiodic nanostructured surfaces for scattering-based optical devices

    Science.gov (United States)

    Lee, Yuk Kwan Sylvanus

    Novel optical devices such as biosensors, color displays and authentication devices can be obtained from the distinctive light scattering properties of resonant nanoparticles and nanostructured arrays. These arrays can be optimized through the choice of material, particle morphology and array geometry. In this thesis, by engineering the multi-frequency colorimetric responses of deterministic aperiodic nanostructured surfaces (DANS) with various spectral Fourier properties, I designed, fabricated and characterized scattering-based devices for optical biosensing and structural coloration applications. In particular, using analytical and numerical optimization, colorimetric biosensors are designed and fabricated with conventional electron beam lithography, and characterized using dark-field scattering imaging as well as image autocorrelation analysis of scattered intensity in the visible spectral range. These sensors, which consist of aperiodic surfaces ranging from quasi-periodic to pseudo-random structures with flat Fourier spectra, sustain highly complex structural resonances that enable a novel optical sensing approach beyond the traditional Bragg scattering. To this end, I have experimentally demonstrated that DANS with engineered structural colors are capable of detecting nanoscale protein monolayers with significantly enhanced sensitivity over periodic structures. In addition, different aperiodic arrays of gold (Au) nanoparticles are integrated with polydimethylsiloxane (PDMS) microfluidic structures by soft-lithographic micro-imprint techniques. Distinctive scattering spectral shifts and spatial modifications of structural color patterns in response to refractive index variations were simultaneously measured. The successful integration of DANS with microfluidics technology has introduced a novel opto-fluidic sensing platform for label-free and multiplexed lab-on-a-chip applications. Moreover, by studying the isotropic scattering properties of homogenized

  15. Engineered Emitters for Improved Silicon Photovoltaics

    Science.gov (United States)

    Kamat, Ronak A.

    In 2014, installation of 5.3GW of new Photovoltaic (PV) systems occurred in the United States, raising the total installed capacity to 16.36GW. Strong growth is predicted for the domestic PV market with analysts reporting goals of 696GW by 2020. Conventional single crystalline silicon cells are the technology of choice, accounting for 90% of the installations in the global commercial market. Cells made of GaAs offer higher efficiencies, but at a substantially higher cost. Thin film technologies such as CIGS and CdTe compete favorably with multi-crystalline Si (u-Si), but at 20% efficiency, still lag the c-Si cell in performance. The c-Si cell can be fabricated to operate at approximately 25% efficiency, but commercially the efficiencies are in the 18-21% range, which is a direct result of cost trade-offs between process complexity and rapid throughput. With the current cost of c-Si cell modules at nearly 0.60/W. The technology is well below the historic metric of 1/W for economic viability. The result is that more complex processes, once cost-prohibitive, may now be viable. An example is Panasonic's HIT cell which operates in the 22-24% efficiency range. To facilitate research and development of novel PV materials and techniques, RIT has developed a basic solar cell fabrication process. Student projects prior to this work had produced cells with 12.8% efficiency using p type substrates. This thesis reports on recent work to improve cell efficiencies while simultaneously expanding the capability of the rapid prototyping process. In addition to the p-Si substrates, cells have been produced using n-Si substrates. The cell emitter, which is often done with a single diffusion or implant has been re-engineered using a dual implant of the same dose. This dual-implanted emitter has been shown to lower contact resistance, increase Voc, and increase the efficiency. A p-Si substrate cell has been fabricated with an efficiency of 14.6% and n-Si substrate cell with a 13

  16. Design and optimization of Ag-dielectric core-shell nanostructures for silicon solar cells

    Directory of Open Access Journals (Sweden)

    Feng-Xiang Chen

    2015-09-01

    Full Text Available Metal-dielectric core-shell nanostructures have been proposed as a light trapping scheme for enhancing the optical absorption of silicon solar cells. As a potential application of such enhanced effects, the scattering efficiencies of three core-shell structures (Ag@SiO2, Ag@TiO2, and Ag@ZrO2 are discussed using the Mie Scattering theory. For compatibility with experiment results, the core diameter and shell thickness are limited to 100 and 30 nm, respectively, and a weighted scattering efficiency is introduced to evaluate the scattering abilities of different nanoparticles under the solar spectrum AM 1.5. The simulated results indicate that the shell material and thickness are two key parameters affecting the weighted scattering efficiency. The SiO2 is found to be an unsuitable shell medium because of its low refractive index. However, using the high refractive index mediumTiO2 in Ag@TiO2 nanoparticles, only the thicker shell (30 nm is more beneficial for light scattering. The ZrO2 is an intermediate refractive index material, so Ag@ZrO2 nanoparticles are the most effective core-shell nanostructures in these silicon solar cells applications.

  17. Laser ablation of a silicon target in chloroform: formation of multilayer graphite nanostructures

    Science.gov (United States)

    Abderrafi, Kamal; García-Calzada, Raúl; Sanchez-Royo, Juan F.; Chirvony, Vladimir S.; Agouram, Saïd; Abargues, Rafael; Ibáñez, Rafael; Martínez-Pastor, Juan P.

    2013-04-01

    With the use of high-resolution transmission electron microscopy, selected area electron diffraction and x-ray photoelectron spectroscopy methods of analysis we show that the laser ablation of a Si target in chloroform (CHCl3) by nanosecond UV pulses (40 ns, 355 nm) results in the formation of about 50-80 nm core-shell nanoparticles with a polycrystalline core composed of small (5-10 nm) Si and SiC mono-crystallites, the core being coated by several layers of carbon with the structure of graphite (the shell). In addition, free carbon multilayer nanostructures (carbon nano-onions) are also found in the suspension. On the basis of a comparison with similar laser ablation experiments implemented in carbon tetrachloride (CCl4), where only bare (uncoated) Si nanoparticles are produced, we suggest that a chemical (solvent decomposition giving rise to highly reactive CH-containing radicals) rather than a physical (solvent atomization followed by carbon nanostructure formation) mechanism is responsible for the formation of graphitic shells. The silicon carbonization process found for the case of laser ablation in chloroform may be promising for silicon surface protection and functionalization.

  18. Nanostructured porous silicon micropatterns as a tool for substrate-conditioned cell research

    Science.gov (United States)

    Punzón-Quijorna, Esther; Sánchez-Vaquero, Vanessa; Muñoz-Noval, Álvaro; Pérez-Roldán, M. Jesus; Martín-Palma, Raúl J.; Rossi, Francois; Climent-Font, Aurelio; Manso-Silván, Miguel; Ruiz, J. Predestinacion García; Torres-Costa, Vicente

    2012-07-01

    The localized irradiation of Si allows a precise patterning at the microscale of nanostructured materials such as porous silicon (PS). PS patterns with precisely defined geometries can be fabricated using ion stopping masks. The nanoscale textured micropatterns were used to explore their influence as microenvironments for human mesenchymal stem cells (hMSCs). In fact, the change of photoluminescence emission from PS upon aging in physiological solution suggests the intense formation of silanol surface groups, which may play a relevant role in ulterior cell adhesion. The experimental results show that hMSCs are sensitive to the surface micropatterns. In this regard, preliminary β-catenin labeling studies reveal the formation of cell to cell interaction structures, while microtubule orientation is strongly influenced by the selective adhesion conditions. Relevantly, Ki-67 assays support a proliferative state of hMSCs on such nanostructured micropatterns comparable to that of standard cell culture platforms, which reinforce the candidature of porous silicon micropatterns to become a conditioning structure for in vitro culture of HMSCs.

  19. Mesoporous silicon oxide films and their uses as templates in obtaining nanostructured conductive polymers

    Science.gov (United States)

    Salgado, R.; Arteaga, G. C.; Arias, J. M.

    2018-04-01

    Obtaining conductive polymers (CPs) for the manufacture of OLEDs, solar cells, electrochromic devices, sensors, etc., has been possible through the use of electrochemical techniques that allow obtaining films of controlled thickness with positive results in different applications. Current trends point towards the manufacture of nanomaterials, and therefore it is necessary to develop methods that allow obtaining CPs with nanostructured morphology. This is possible by using a porous template to allow the growth of the polymeric materials. However, prior and subsequent treatments are required to separate the material from the template so that it can be evaluated in the applications mentioned above. This is why mesoporous silicon oxide films (template) are essential for the synthesis of nanostructured polymers since both the template and the polymer are obtained on the electrode surface, and therefore it is not necessary to separate the material from the template. Thus, the material can be evaluated directly in the applications mentioned above. The dimensions of the resulting nanostructures will depend on the power, time and technique used for electropolymerization as well as the monomer and the surfactant of the mesoporous film.

  20. Suppressing light reflection from polycrystalline silicon thin films through surface texturing and silver nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, Perveen [Department of Physics, University at Albany-SUNY, Albany, New York 12222 (United States); Huang, Mengbing, E-mail: mhuang@albany.edu; Kadakia, Nirag; Spratt, William; Malladi, Girish; Bakhru, Hassarum [SUNY College of Nanoscale Science and Engineering, Albany, New York 12203 (United States)

    2014-09-21

    This work demonstrates a novel method combining ion implantation and silver nanostructures for suppressing light reflection from polycrystalline silicon thin films. Samples were implanted with 20-keV hydrogen ions to a dose of 10¹⁷/cm², and some of them received an additional argon ion implant to a dose of 5×10¹⁵ /cm² at an energy between 30 and 300 keV. Compared to the case with a single H implant, the processing involved both H and Ar implants and post-implantation annealing has created a much higher degree of surface texturing, leading to a more dramatic reduction of light reflection from polycrystalline Si films over a broadband range between 300 and 1200 nm, e.g., optical reflection from the air/Si interface in the AM1.5 sunlight condition decreasing from ~30% with an untextured surface to below 5% for a highly textured surface after post-implantation annealing at 1000°C. Formation of Ag nanostructures on these ion beam processed surfaces further reduces light reflection, and surface texturing is expected to have the benefit of diminishing light absorption losses within large-size (>100 nm) Ag nanoparticles, yielding an increased light trapping efficiency within Si as opposed to the case with Ag nanostructures on a smooth surface. A discussion of the effects of surface textures and Ag nanoparticles on light trapping within Si thin films is also presented with the aid of computer simulations.

  1. Fabrication of Silicon nanostructures by UHV-STM lithography in Self-Assembled Monolayers

    International Nuclear Information System (INIS)

    Sundermann, M.; Brechling, A.; Rott, K.; Meyners, D.; Kleineberg, U.; Heinzmann, U.; Knueller, A.; Eck, W.; Goelzhueuser, A.; Grunze, M.

    2002-01-01

    Our approach utilizes UHV-STM writing in Self-Assembled Monolayers (SAM). SAMs form highly-ordered ultrathin (∼2-3 nm) monomolecular layers on top of pre-activated Si(100) or Si(111) surfaces. After patterning by UHV-STM writing in constant-current mode at different write parameters (gap voltage, electron dose) the modified Self-Assembled Monolayer serves as an etch mask for an anisotropic wet etch transfer (two-step etch process in aqueous solutions of 5 % HF and 1 M KOH), of the write structure into the silicon substrate. The corresponding silicon nano-structures have been analyzed afterwards by AFM or SEM to characterize the pattern accuracy. We have studied the suitability of three different types of SAMs on silicon single-crystals. Alkyl-chain-type SAMs like Octadecylsilane (ODS) monolayer have been formed by immersion of hydroxylated Si(100) in Octadecyltrichlorosilane (CH 3 (CH 27 SiCl 3 ) while SAMs with aromatic spacer groups such as Hydroxybiphenyl (HBP, (C 6 H 6 ) 2 OH) and Ethoxybiphenyl silane (EBP, (C 6 H 6 ) 2 O(CH 2 ) 3 Si(OCH 3 ) 3 ) are formed on Si(111). (Authors)

  2. Fabrication of Up-Conversion Phosphor Films on Flexible Substrates Using a Nanostructured Organo-Silicon.

    Science.gov (United States)

    Jeon, Young-Sun; Kim, Tae-Un; Kim, Seon-Hoon; Lee, Young-Hwan; Choi, Pil-Son; Hwang, Kyu-Seog

    2018-03-01

    Up-conversion phosphors have attracted considerable attention because of their applications in solid-state lasers, optical communications, flat-panel displays, photovoltaic cells, and biological labels. Among them, NaYF4 is reported as one of the most efficient hosts for infrared to visible photon up-conversion of Yb3+ and Er3+ ions. However, a low-temperature method is required for industrial scale fabrication of photonic and optoelectronic devices on flexible organic substrates. In this study, hexagonal β-NaYF4: 3 mol% Yb3+, 3 mol% Er3+ up-conversion phosphor using Ca2+ was prepared by chemical solution method. Then, we synthesized a nanostructured organo-silicon compound from methyl tri-methoxysilane and 3-glycidoxy-propyl-trimethoxy-silane. The transmittance of the organo-silicon compound was found to be over 90% in the wavelength range of 400~1500 nm. Then we prepared a fluoride-based phosphor paste by mixing the organo-silicon compound with Na(Ca)YF4:Yb3+, Er3+. Subsequently, this paste was coated on polyethylene terephthalate, followed by heat-treatment at 120 °C. The visible emission of the infrared detection card was found to be at 655 nm and 661 nm an excitation wavelength of 980 nm.

  3. Nanostructured porous silicon: The winding road from photonics to cell scaffolds. A review.

    Directory of Open Access Journals (Sweden)

    Jacobo eHernandez-Montelongo

    2015-05-01

    Full Text Available For over 20 years nanostructured porous silicon (nanoPS has found a vast number of applications in the broad fields of photonics and optoelectronics, triggered by the discovery of its photoluminescent behavior in 1990. Besides, its biocompatibility, biodegradability, and bioresorbability make porous silicon (PSi an appealing biomaterial. These properties are largely a consequence of its particular susceptibility to oxidation, leading to the formation of silicon oxide which is readily dissolved by body fluids. This paper reviews the evolution of the applications of PSi and nanoPS from photonics through biophotonics, to their use as cell scaffolds, whether as an implantable substitute biomaterial, mainly for bony and ophthalmological tissues, or as an in-vitro cell conditioning support, especially for pluripotent cells. For any of these applications, PSi/nanoPS can be used directly after synthesis from Si wafers, upon appropriate surface modification processes, or as a composite biomaterial. Unedited studies of fluorescently active PSi structures for cell culture are brought to evidence the margin for new developments.

  4. High performance nanostructured Silicon heterojunction for water splitting on large scales

    KAUST Repository

    Bonifazi, Marcella

    2017-11-02

    In past years the global demand for energy has been increasing steeply, as well as the awareness that new sources of clean energy are essential. Photo-electrochemical devices (PEC) for water splitting applications have stirred great interest, and different approach has been explored to improve the efficiency of these devices and to avoid optical losses at the interfaces with water. These include engineering materials and nanostructuring the device\\'s surfaces [1]-[2]. Despite the promising initial results, there are still many drawbacks that needs to be overcome to reach large scale production with optimized performances [3]. We present a new device that relies on the optimization of the nanostructuring process that exploits suitably disordered surfaces. Additionally, this device could harvest light on both sides to efficiently gain and store the energy to keep the photocatalytic reaction active.

  5. High Sensitivity and High Detection Specificity of Gold-Nanoparticle-Grafted Nanostructured Silicon Mass Spectrometry for Glucose Analysis.

    Science.gov (United States)

    Tsao, Chia-Wen; Yang, Zhi-Jie

    2015-10-14

    Desorption/ionization on silicon (DIOS) is a high-performance matrix-free mass spectrometry (MS) analysis method that involves using silicon nanostructures as a matrix for MS desorption/ionization. In this study, gold nanoparticles grafted onto a nanostructured silicon (AuNPs-nSi) surface were demonstrated as a DIOS-MS analysis approach with high sensitivity and high detection specificity for glucose detection. A glucose sample deposited on the AuNPs-nSi surface was directly catalyzed to negatively charged gluconic acid molecules on a single AuNPs-nSi chip for MS analysis. The AuNPs-nSi surface was fabricated using two electroless deposition steps and one electroless etching step. The effects of the electroless fabrication parameters on the glucose detection efficiency were evaluated. Practical application of AuNPs-nSi MS glucose analysis in urine samples was also demonstrated in this study.

  6. Superior in vitro biological response and mechanical properties of an implantable nanostructured biomaterial: Nanohydroxyapatite-silicone rubber composite.

    Science.gov (United States)

    Thein-Han, W W; Shah, J; Misra, R D K

    2009-09-01

    A potential approach to achieving the objective of favorably modulating the biological response of implantable biopolymers combined with good mechanical properties is to consider compounding the biopolymer with a bioactive nanocrystalline ceramic biomimetic material with high surface area. The processing of silicone rubber (SR)-nanohydroxyapatite (nHA) composite involved uniform dispersion of nHA via shear mixing and ultrasonication, followed by compounding at sub-ambient temperature, and high-pressure solidification when the final curing reaction occurs. The high-pressure solidification approach enabled the elastomer to retain the high elongation of SR even in the presence of the reinforcement material, nHA. The biological response of the nanostructured composite in terms of initial cell attachment, cell viability and proliferation was consistently greater on SR-5wt.% nHA composite surface compared to pure SR. Furthermore, in the nanocomposite, cell spreading, morphology and density were distinctly different from that of pure SR. Pre-osteoblasts grown on SR-nHA were well spread, flat, large in size with a rough cell surface, and appeared as a group. In contrast, these features were less pronounced in SR (e.g. smooth cell surface, not well spread). Interestingly, an immunofluorescence study illustrated distinct fibronectin expression level, and stronger vinculin focal adhesion contacts associated with abundant actin stress fibers in pre-osteoblasts grown on the nanocomposite compared to SR, implying enhanced cell-substrate interaction. This finding was consistent with the total protein content and SDS-PAGE analysis. The study leads us to believe that further increase in nHA content in the SR matrix beyond 5wt.% will encourage even greater cellular response. The integration of cellular and molecular biology with materials science and engineering described herein provides a direction for the development of a new generation of nanostructured materials.

  7. Nanostructured materials based on nano-ZrO2 in the nuclear-power engineering

    International Nuclear Information System (INIS)

    Garibov, A.A.; Agayev, T.N.; Imanova, G.T.

    2014-01-01

    Full text : The review of the results of research, development and use of nanomaterials in the nuclear-power engineering and technology have been presented. The basic properties of nanostructured materials are given. The prospects for the use of nanomaterials in the nuclear-power engineering, associated with the creation of nanostructured materials and coatings for structural elements of nuclear-power enginnering plant and future themal nuclear reactor to increase hardness and strength characteristics, raising corrosion and radiation resistance have been considered

  8. Raspberry-like Nanostructured Silicon Composite Anode for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Fang, Shan; Tong, Zhenkun; Nie, Ping; Liu, Gao; Zhang, Xiaogang

    2017-06-07

    Adjusting the particle size and nanostructure or applying carbon materials as the coating layers is a promising method to hold the volume expansion of Si for its practical application in lithium-ion batteries (LIBs). Herein, the mild carbon coating combined with a molten salt reduction is precisely designed to synthesize raspberry-like hollow silicon spheres coated with carbon shells (HSi@C) as the anode materials for LIBs. The HSi@C exhibits a remarkable electrochemical performance; a high reversible specific capacity of 886.2 mAh g -1 at a current density of 0.5 A g -1 after 200 cycles is achieved. Moreover, even after 500 cycles at a current density of 2.0 A g -1 , a stable capacity of 516.7 mAh g -1 still can be obtained.

  9. Effect of silicon-nanoparticle addition on the nanostructure of polythiophene: fullurene bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Kim, Joonhyeon; Nam, Sungho; Jeong, Jaehoon; Kim, Hwajeong; Kim, Youngkyoo

    2012-01-01

    We investigated the nanostructure change in bulk heterojunction films of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C 61 (PCBM) before and after adding silicon nanoparticles (SiNP) by employing synchrotron radiation grazing incidence-angle X-ray diffraction (GIXD) techniques. The GIXD results showed a gradual reduction of the P3HT (100) diffraction intensity in the out-of-plane (OOP) direction as the SiNP content was increased. Interestingly, a (100) intensity in the in-plane (IP) direction newly appeared when a small amount of SiNP was added, but it faded at higher SiNP contents. In particular, the addition of 2 wt.% SiNP increased the (100) intensity in both the OOP and the IP directions, leading to improved solar cell performance due to enhanced charge transport in the P3HT domains.

  10. Towards the Development of Electrical Biosensors Based on Nanostructured Porous Silicon

    Science.gov (United States)

    Recio-Sánchez, Gonzalo; Torres-Costa, Vicente; Manso, Miguel; Gallach, Darío; López-García, Juan; Martín-Palma, Raúl J.

    2010-01-01

    The typical large specific surface area and high reactivity of nanostructured porous silicon (nanoPS) make this material very suitable for the development of sensors. Moreover, its biocompatibility and biodegradability opens the way to the development of biosensors. As such, in this work the use of nanoPS in the field of electrical biosensing is explored. More specifically, nanoPS-based devices with Al/nanoPS/Al and Au-NiCr/nanoPS/Au-NiCr structures were fabricated for the electrical detection of glucose and Escherichia Coli bacteria at different concentrations. The experimental results show that the current-voltage characteristics of these symmetric metal/nanoPS/metal structures strongly depend on the presence/absence and concentration of species immobilized on the surface.

  11. Size-dependent Fano Interaction in the Laser-etched Silicon Nanostructures

    Directory of Open Access Journals (Sweden)

    Kumar Rajesh

    2008-01-01

    Full Text Available AbstractPhoto-excitation and size-dependent Raman scattering studies on the silicon (Si nanostructures (NSs prepared by laser-induced etching are presented here. Asymmetric and red-shifted Raman line-shapes are observed due to photo-excited Fano interaction in the quantum confined nanoparticles. The Fano interaction is observed between photo-excited electronic transitions and discrete phonons in Si NSs. Photo-excited Fano studies on different Si NSs show that the Fano interaction is high for smaller size of Si NSs. Higher Fano interaction for smaller Si NSs is attributed to the enhanced interference between photo-excited electronic Raman scattering and phonon Raman scattering.

  12. Improved silicon carbide for advanced heat engines

    Science.gov (United States)

    Whalen, T. J.; Winterbottom, W. L.

    1986-01-01

    Work performed to develop silicon carbide materials of high strength and to form components of complex shape and high reliability is described. A beta-SiC powder and binder system was adapted to the injection molding process and procedures and process parameters developed capable of providing a sintered silicon carbide material with improved properties. The initial effort has been to characterize the baseline precursor materials (beta silicon carbide powder and boron and carbon sintering aids), develop mixing and injection molding procedures for fabricating test bars, and characterize the properties of the sintered materials. Parallel studies of various mixing, dewaxing, and sintering procedures have been carried out in order to distinguish process routes for improving material properties. A total of 276 MOR bars of the baseline material have been molded, and 122 bars have been fully processed to a sinter density of approximately 95 percent. The material has a mean MOR room temperature strength of 43.31 ksi (299 MPa), a Weibull characteristic strength of 45.8 ksi (315 MPa), and a Weibull modulus of 8.0. Mean values of the MOR strengths at 1000, 1200, and 14000 C are 41.4, 43.2, and 47.2 ksi, respectively. Strength controlling flaws in this material were found to consist of regions of high porosity and were attributed to agglomerates originating in the initial mixing procedures. The mean stress rupture lift at 1400 C of five samples tested at 172 MPa (25 ksi) stress was 62 hours and at 207 MPa (30 ksi) stress was 14 hours. New fluid mixing techniques have been developed which significantly reduce flaw size and improve the strength of the material. Initial MOR tests indicate the strength of the fluid-mixed material exceeds the baseline property by more than 33 percent.

  13. Suppressing light reflection from polycrystalline silicon thin films through surface texturing and silver nanostructures

    International Nuclear Information System (INIS)

    Akhter, Perveen; Huang, Mengbing; Kadakia, Nirag; Spratt, William; Malladi, Girish; Bakhru, Hassarum

    2014-01-01

    This work demonstrates a novel method combining ion implantation and silver nanostructures for suppressing light reflection from polycrystalline silicon thin films. Samples were implanted with 20-keV hydrogen ions to a dose of 10 17 /cm 2 , and some of them received an additional argon ion implant to a dose of 5 × 10 15 /cm 2 at an energy between 30 and 300 keV. Compared to the case with a single H implant, the processing involved both H and Ar implants and post-implantation annealing has created a much higher degree of surface texturing, leading to a more dramatic reduction of light reflection from polycrystalline Si films over a broadband range between 300 and 1200 nm, e.g., optical reflection from the air/Si interface in the AM1.5 sunlight condition decreasing from ∼30% with an untextured surface to below 5% for a highly textured surface after post-implantation annealing at 1000 °C. Formation of Ag nanostructures on these ion beam processed surfaces further reduces light reflection, and surface texturing is expected to have the benefit of diminishing light absorption losses within large-size (>100 nm) Ag nanoparticles, yielding an increased light trapping efficiency within Si as opposed to the case with Ag nanostructures on a smooth surface. A discussion of the effects of surface textures and Ag nanoparticles on light trapping within Si thin films is also presented with the aid of computer simulations.

  14. Silicon-ion-implanted PMMA with nanostructured ultrathin layers for plastic electronics

    Science.gov (United States)

    Hadjichristov, G. B.; Ivanov, Tz E.; Marinov, Y. G.

    2014-12-01

    Being of interest for plastic electronics, ion-beam produced nanostructure, namely silicon ion (Si+) implanted polymethyl-methacrylate (PMMA) with ultrathin nanostructured dielectric (NSD) top layer and nanocomposite (NC) buried layer, is examined by electric measurements. In the proposed field-effect organic nanomaterial structure produced within the PMMA network by ion implantation with low energy (50 keV) Si+ at the fluence of 3.2 × 1016 cm-2 the gate NSD is ion-nanotracks-modified low-conductive surface layer, and the channel NC consists of carbon nanoclusters. In the studied ion-modified PMMA field-effect configuration, the gate NSD and the buried NC are formed as planar layers both with a thickness of about 80 nm. The NC channel of nano-clustered amorphous carbon (that is an organic semiconductor) provides a huge increase in the electrical conduction of the material in the subsurface region, but also modulates the electric field distribution in the drift region. The field effect via the gate NSD is analyzed. The most important performance parameters, such as the charge carrier field-effect mobility and amplification of this particular type of PMMA- based transconductance device with NC n-type channel and gate NSD top layer, are determined.

  15. Band-gap dependence of field emission from one-dimensional nanostructures grown on n-type and p-type silicon substrates

    Science.gov (United States)

    Chang, C. S.; Chattopadhyay, S.; Chen, L. C.; Chen, K. H.; Chen, C. W.; Chen, Y. F.; Collazo, R.; Sitar, Z.

    2003-09-01

    Field emission of electrons from narrow-band-gap and wide-band-gap one-dimensional nanostructures were studied. N-type silicon substrates enhanced the emission from the low-band-gap silicon nanowires and carbon nanotubes, whereas p-type substrates were a better choice for field emission from wide-band-gap silicon carbon nitride nanocrystalline thin films and nanorods. The role of the substrate-nanostructure interface was modeled based on different junction mechanisms to explain, qualitatively, the fundamentally different emission behavior of these nanostructures when n- and p-type silicon substrates were used. The results could be explained on the basis of simple carrier transport across the silicon-silicon nanowire interface and subsequent tunneling of electrons for the silicon nanowires. Schottky barrier theory can explain the better field emission of electrons from the n-type silicon supported carbon nanotubes. The decreased barrier height at the interface of the silicon-silicon carbon nitride heterojunction, when p-type silicon substrate was used, could explain the superior field emission in comparison to when n-type silicon substrates were used.

  16. New Nanostructured Li 2 S/Silicon Rechargeable Battery with High Specific Energy

    KAUST Repository

    Yang, Yuan

    2010-04-14

    Rechargeable lithium ion batteries are important energy storage devices; however, the specific energy of existing lithium ion batteries is still insufficient for many applications due to the limited specific charge capacity of the electrode materials. The recent development of sulfur/mesoporous carbon nanocomposite cathodes represents a particularly exciting advance, but in full battery cells, sulfur-based cathodes have to be paired with metallic lithium anodes as the lithium source, which can result in serious safety issues. Here we report a novel lithium metal-free battery consisting of a Li 2S/mesoporous carbon composite cathode and a silicon nanowire anode. This new battery yields a theoretical specific energy of 1550 Wh kg ?1, which is four times that of the theoretical specific energy of existing lithium-ion batteries based on LiCoO2 cathodes and graphite anodes (∼410 Wh kg?1). The nanostructured design of both electrodes assists in overcoming the issues associated with using sulfur compounds and silicon in lithium-ion batteries, including poor electrical conductivity, significant structural changes, and volume expansion. We have experimentally realized an initial discharge specific energy of 630 Wh kg ?1 based on the mass of the active electrode materials. © 2010 American Chemical Society.

  17. Silicon and Germanium Nanostructures for Photovoltaic Applications: Ab-Initio Results

    Directory of Open Access Journals (Sweden)

    Pulci Olivia

    2010-01-01

    Full Text Available Abstract Actually, most of the electric energy is being produced by fossil fuels and great is the search for viable alternatives. The most appealing and promising technology is photovoltaics. It will become truly mainstream when its cost will be comparable to other energy sources. One way is to significantly enhance device efficiencies, for example by increasing the number of band gaps in multijunction solar cells or by favoring charge separation in the devices. This can be done by using cells based on nanostructured semiconductors. In this paper, we will present ab-initio results of the structural, electronic and optical properties of (1 silicon and germanium nanoparticles embedded in wide band gap materials and (2 mixed silicon-germanium nanowires. We show that theory can help in understanding the microscopic processes important for devices performances. In particular, we calculated for embedded Si and Ge nanoparticles the dependence of the absorption threshold on size and oxidation, the role of crystallinity and, in some cases, the recombination rates, and we demonstrated that in the case of mixed nanowires, those with a clear interface between Si and Ge show not only a reduced quantum confinement effect but display also a natural geometrical separation between electron and hole.

  18. Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sundberg, G.J.; Vartabedian, A.M.; Wade, J.A.; White, C.S. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.

    1994-10-01

    The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfully obtain heat engine quality joins.

  19. Engineering of silicon surfaces at the micro- and nanoscales for cell adhesion and migration control

    Directory of Open Access Journals (Sweden)

    Torres-Costa V

    2012-02-01

    Full Text Available Vicente Torres-Costa1, Gonzalo Martínez-Muñoz2, Vanessa Sánchez-Vaquero3, Álvaro Muñoz-Noval1, Laura González-Méndez3, Esther Punzón-Quijorna1,4, Darío Gallach-Pérez1, Miguel Manso-Silván1, Aurelio Climent-Font1,4, Josefa P García-Ruiz3, Raúl J Martín-Palma11Department of Applied Physics, 2Department of Computer Science, 3Department of Molecular Biology, 4Centre for Micro Analysis of Materials, Universidad Autónoma de Madrid, Madrid, SpainAbstract: The engineering of surface patterns is a powerful tool for analyzing cellular communication factors involved in the processes of adhesion, migration, and expansion, which can have a notable impact on therapeutic applications including tissue engineering. In this regard, the main objective of this research was to fabricate patterned and textured surfaces at micron- and nanoscale levels, respectively, with very different chemical and topographic characteristics to control cell–substrate interactions. For this task, one-dimensional (1-D and two-dimensional (2-D patterns combining silicon and nanostructured porous silicon were engineered by ion beam irradiation and subsequent electrochemical etch. The experimental results show that under the influence of chemical and morphological stimuli, human mesenchymal stem cells polarize and move directionally toward or away from the particular stimulus. Furthermore, a computational model was developed aiming at understanding cell behavior by reproducing the surface distribution and migration of human mesenchymal stem cells observed experimentally.Keywords: surface patterns, silicon, hMSCs, ion-beam patterning

  20. Research Update: Phonon engineering of nanocrystalline silicon thermoelectrics

    Directory of Open Access Journals (Sweden)

    Junichiro Shiomi

    2016-10-01

    Full Text Available Nanocrystalline silicon thermoelectrics can be a solution to improve the cost-effectiveness of thermoelectric technology from both material and integration viewpoints. While their figure-of-merit is still developing, recent advances in theoretical/numerical calculations, property measurements, and structural synthesis/fabrication have opened up possibilities to develop the materials based on fundamental physics of phonon transport. Here, this is demonstrated by reviewing a series of works on nanocrystalline silicon materials using calculations of multiscale phonon transport, measurements of interfacial heat conduction, and synthesis from nanoparticles. Integration of these approaches allows us to engineer phonon transport to improve the thermoelectric performance by introducing local silicon-oxide structures.

  1. Trace detection of herbicides by SERS technique, using SERS-active substrates fabricated from different silver nanostructures deposited on silicon

    International Nuclear Information System (INIS)

    Dao, Tran Cao; Luong, Truc Quynh Ngan; Nguyen, Ngoc Hai; Kieu, Ngoc Minh; Luong, Thi Thuy; Cao, Tuan Anh; Le, Van Vu

    2015-01-01

    In this report we present the initial results of the use of different silver nanostructures deposited on silicon for trace detection of paraquat (a commonly used herbicide) using the surface-enhanced Raman scattering (SERS) effect. More specifically, the SERS-active substrates were fabricated from silver nanoparticles (AgNPs) deposited onto the flat surface of a silicon wafer (AgNPs@Si substrate), as well as on the surface of an obliquely aligned silicon nanowire (SiNW) array (AgNPs@SiNWs substrate), and from silver nanodendrites (AgNDs) deposited onto the flat surface of a silicon wafer (AgNDs@Si substrate). Results showed that with the change of the structure of the SERS-active substrate, higher levels of SERS enhancement have been achieved. Specifically, with the fabricated AgNDs@Si substrate, paraquat concentration as low as 1 ppm can be detected. (paper)

  2. Plasmonic back contacts with non-ordered Ag nanostructures for light trapping in thin-film silicon solar cells

    International Nuclear Information System (INIS)

    Paetzold, Ulrich W.; Meier, Matthias; Moulin, Etienne; Smirnov, Vladimir; Pieters, Bart E.; Rau, Uwe; Carius, Reinhard

    2013-01-01

    In this work, we investigate the light trapping of thin-film silicon solar cells which apply plasmonic Ag back contacts with non-ordered Ag nanostructures. The preparation, characterization and three-dimensional electromagnetic simulations of these back contacts with various distributions of non-ordered Ag nanostructures are presented. The measured reflectance spectra of the Ag back contacts with non-ordered nanostructures in air are well reproduced in reflectance spectra derived from the three-dimensional electromagnetic simulations of isolated nanostructures on Ag back contacts. The light–matter interaction of these nanostructures is given by localized surface plasmons and, thus, the measured diffuse reflectance of the back contacts is attributed to plasmon-induced light scattering. A significant plasmonic light-trapping effect in n-i-p substrate-type μc-Si:H thin-film solar cell prototypes which apply a Ag back contact with non-ordered nanostructures is identified when compared with flat reference solar cells

  3. Engineering Nanostructural Routes for Enhancing Thermoelectric Performance: Bulk to Nanoscale.

    Science.gov (United States)

    Mohanraman, Rajeshkumar; Lan, Tian-Wey; Hsiung, Te-Chih; Amada, Dedi; Lee, Ping-Chung; Ou, Min-Nan; Chen, Yang-Yuan

    2015-01-01

    Thermoelectricity is a very important phenomenon, especially its significance in heat-electricity conversion. If thermoelectric devices can be effectively applied to the recovery of the renewable energies, such as waste heat and solar energy, the energy shortage, and global warming issues may be greatly relieved. This review focusses recent developments on the thermoelectric performance of a low-dimensional material, bulk nanostructured materials, conventional bulk materials etc. Particular emphasis is given on, how the nanostructure in nanostructured composites, confinement effects in one-dimensional nanowires and doping effects in conventional bulk composites plays an important role in ZT enhancement.

  4. Characterization of Ag-porous silicon nanostructured layer formed by an electrochemical etching of p-type silicon surface for bio-application

    Science.gov (United States)

    Naddaf, M.; Al-Mariri, A.; Haj-Mhmoud, N.

    2017-06-01

    Nanostructured layers composed of silver-porous silicon (Ag-PS) have been formed by an electrochemical etching of p-type (1 1 1) silicon substrate in a AgNO3:HF:C2H5OH solution at different etching times (10 min-30 min). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) results reveal that the produced layers consist of Ag dendrites and a silicon-rich porous structure. The nanostructuring nature of the layer has been confirmed by spatial micro-Raman scattering and x-ray diffraction techniques. The Ag dendrites exhibit a surface-enhanced Raman scattering (SERS) spectrum, while the porous structure shows a typical PS Raman spectrum. Upon increasing the etching time, the average size of silicon nanocrystallite in the PS network decreases, while the average size of Ag nanocrystals is slightly affected. In addition, the immobilization of prokaryote Salmonella typhimurium DNA via physical adsorption onto the Ag-PS layer has been performed to demonstrate its efficiency as a platform for detection of biological molecules using SERS.

  5. A semi-local quasi-harmonic model to compute the thermodynamic and mechanical properties of silicon nanostructures

    International Nuclear Information System (INIS)

    Zhao, H; Aluru, N R

    2007-01-01

    This paper presents a semi-local quasi-harmonic model with local phonon density of states (LPDOS) to compute the thermodynamic and mechanical properties of silicon nanostructures at finite temperature. In contrast to an earlier approach (Tang and Aluru 2006 Phys. Rev. B 74 235441), where a quasi-harmonic model with LPDOS computed by a Green's function technique (QHMG) was developed considering many layers of atoms, the semi-local approach considers only two layers of atoms to compute the LPDOS. We show that the semi-local approach combines the accuracy of the QHMG approach and the computational efficiency of the local quasi-harmonic model. We present results for several silicon nanostructures to address the accuracy and efficiency of the semi-local approach

  6. From Nanostructure to Nano Biosensor: Institute of Nano Electronic Engineering (INEE), UniMAP Experience

    OpenAIRE

    Hashim, U; Foo, K L

    2011-01-01

    Nanostructure is defined as something that has a physical dimension smaller than 100 nanometers, ranging from clusters and/or to dimensional layers of atoms. There are three most important nanostructures that are extensively studied and researched in various organizations including Institute of Nano Electronic Engineering (INEE) in UniMAP. These include quantum dot, nanowire, and nanogap, which have been successfully designed and fabricated using in-house facilities available. These are subse...

  7. Some aspects of applying nanostructured materials in air filtration, water filtration and electrical engineering

    Science.gov (United States)

    Kimmer, Dusan; Vincent, Ivo; Lovecka, Lenka; Kazda, Tomas; Giurg, Adam; Skorvan, Ondrej

    2017-05-01

    Nanostructures prepared from nanofibres and nanostructured composites prepared from nanofibres and fillers are gradually becoming increasingly demanded materials for applications in various industrial branches connected with catalysis, environment protection (air filtration, waste water treatment, sound absorption), in biological engineering, electronics (battery separators, electrode materials), etc. Selected applications of these materials prepared in the company SPUR a.s. are summed up in the following presentation.

  8. Fabrication of ultra-high aspect ratio (>160:1) silicon nanostructures by using Au metal assisted chemical etching

    Science.gov (United States)

    Li, Hailiang; Ye, Tianchun; Shi, Lina; Xie, Changqing

    2017-12-01

    We present a facile and effective approach for fabricating high aspect ratio, dense and vertical silicon nanopillar arrays, using a combination of metal etching following electron-beam lithography and Au metal assisted chemical etching (MacEtch). Ti/Au nanostructures used as catalysts in MacEtch are formed by single layer resist-based electron-beam exposure followed by ion beam etching. The effects of MacEtch process parameters, including half period, etching time, the concentrations of H2O2 and HF, etching temperature and drying method are systematically investigated. Especially, we demonstrate an enhancement of etching quality by employing cold MacEtch process, and an enhancement in preventing the collapse of high aspect ratio nanostructures by employing low surface tension rinse liquid and natural evaporation in the drying stage. Using an optimized MacEtch process, vertical silicon nanopillar arrays with a period of 250 nm and aspect ratio up to 160:1 are realized. Our results should be instructive for exploring the achievable aspect ratio limit in silicon nanostructures and may find potential applications in photovoltaic devices, thermoelectric devices and x-ray diffractive optics.

  9. Organic nanostructures on silicon, created with semitransparent polystyrene spheres and 248 nm laser pulses

    International Nuclear Information System (INIS)

    Rothe, Erhard W; Manke, Charles W; Piparia, Reema; Baird, Ronald J

    2008-01-01

    Arrays of nanostructures are made starting with a template of close-packed, polystyrene spheres on a silicon surface. The spheres are either 1.091 or 2.99 μm in diameter (d) and are of polystyrene (PS). They are irradiated with a pulse of either 308 or 248 nm light to which they are transparent and semitransparent, respectively. A transparent sphere with d = 1.091 μm diameter concentrates incident light onto a small substrate area. As has been previously reported, that creates silicon nanobumps that rise from circular craters. At 248 nm and d = 2.99 μm, the light energy is mainly absorbed, destroys the sphere, and leaves a shrunken mass (typically about 500 nm wide and 100 nm high) of organic material that is probably polystyrene and its thermal degradation products. At 248 nm and d = 1.091 μm, the residual organic structures are on the order of 300 nm wide and 100 nm high. A distinctive feature is that these organic structures are connected by filaments that are on the order of 50 nm wide and 10 nm high. Filaments form because the close-packed PS spheres expand into each other during the early part of the laser pulse, and then, as the main structures shrink, their viscoelasticity leads to threads between them. Our results with 248 nm and d = 1.091 μm differ from those described by Huang et al with 248 nm and d = 1.0 μm. Future studies might include the further effect of wavelength and fluence upon the process as well the use of other materials and the replacement of nanospheres by other focusing shapes, such as ellipsoids or rods

  10. Broadband antireflection and absorption enhancement of ultrathin silicon solar microcells enabled with density-graded surface nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Lesley; Kang, Dongseok; Lee, Sung-Min; Li, Weigu; Hunter, Hajirah [Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089 (United States); Yoon, Jongseung, E-mail: js.yoon@usc.edu [Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089 (United States); Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States)

    2014-06-02

    Density-graded surface nanostructures are implemented on ultrathin silicon solar microcells by silver-nanoparticle-catalyzed wet chemical etching to enable near-zero surface reflection over a broad wavelength range of incident solar spectrum as well as non-zeroth order diffraction and light trapping for longer wavelength photons, thereby achieving augmented photon absorption for ultrathin silicon microcells in a simple, cost-effective manner. The increase of absorbed photon flux through the “black silicon (b-Si)” surface translates directly into the corresponding enhancement of photovoltaic performance, where 5.7-μm b-Si microcells with the rational design of device configuration exhibit improved energy conversion efficiency by 148% and 50% with and without a diffuse backside reflector, respectively, compared to devices from the bare silicon without b-Si implementation. Systematic studies on nanostructured morphology, optical and electrical properties of b-Si microcells, together with semi-empirical numerical modeling of photon absorption, provide key aspects of underlying materials science and physics.

  11. Nanostructure formation upon femtosecond ablation from silicon: Effect of double pulses

    Science.gov (United States)

    Reif, Juergen; Varlamova, Olga; Bounhalli, Mourad; Muth, Marco; Arguirov, Tzanimir

    2012-09-01

    To study the dynamics of laser-ablation induced structure formation (LIPPS), silicon was irradiated by (above-threshold) pulse pairs with a variable time-lag between 100 fs and a few picoseconds. With increasing pulse-to-pulse delay we find a significant change in ablated-area morphology: the central range of the irradiated spot becomes less and less depressed whereas a surrounding ring structure exhibits increasingly coarser modulation, typical for strong irradiation, where the ripples are characterized by an alternation between elevation above and depression below the unaffected surface level. At the spot center the ablation depth decreases with increasing pulse separation, showing only structures usually observed for weak irradiation. Micro-Raman spectroscopy of the modified areas indicates an unexpectedly high, almost mono-dispersed, abundance of confined nanostructures. The results clearly seem to rule out structure formation by any interference-induced modulated ablation. Instead, they support the model of self-organized structure formation upon the creation of a thermally unstable, "soft" state of the target after laser impact.

  12. Optical spectra of composite silver-porous silicon (Ag-pSi) nanostructure based periodical lattice

    Science.gov (United States)

    Amedome Min-Dianey, Kossi Aniya; Zhang, Hao-Chun; Brohi, Ali Anwar; Yu, Haiyan; Xia, Xinlin

    2018-03-01

    Numerical finite differential time domain (FDTD) tools were used in this study for predicting the optical characteristics through the nanostructure of composite silver-porous silicon (Ag-pSi) based periodical lattice. This is aimed at providing an interpretation of the optical spectra at known porosity in improvement of the light manipulating efficiency through a proposed structure. With boundary conditions correctly chosen, the numerical simulation was achieved using FDTD Lumerical solutions. This was used to investigate the effect of porosity and the number of layers on the reflection, transmission and absorption characteristics through a proposed structure in a visible wavelength range of 400-750 nm. The results revealed that the higher the number of layers, the lower the reflection. Also, the reflection increases with porosity increase. The transmission characteristics were the inverse to those found in the case of reflection spectra and optimum transmission was attained at high number of layers. Also, increase in porosity results in reduced transmission. Increase in porosity as well as in the number of layers led to an increase in absorption. Therefore, absorption into such structure can be enhanced by elevating the number of layers and the degree of porosity.

  13. Exploring Critical Factors Affecting Strain Distribution in 1D Silicon-Based Nanostructures for Lithium-Ion Battery Anodes.

    Science.gov (United States)

    Son, Yoonkook; Sim, Soojin; Ma, Hyunsoo; Choi, Min; Son, Yeonguk; Park, Noejung; Cho, Jaephil; Park, Minjoon

    2018-03-07

    Despite the advantage of high capacity, the practical use of the silicon anode is still hindered by large volume expansion during the severe pulverization lithiation process, which results in electrical contact loss and rapid capacity fading. Here, a combined electrochemical and computational study on the factor for accommodating volume expansion of silicon-based anodes is shown. 1D silicon-based nanostructures with different internal spaces to explore the effect of spatial ratio of voids and their distribution degree inside the fibers on structural stability are designed. Notably, lotus-root-type silicon nanowires with locally distributed void spaces can improve capacity retention and structural integrity with minimum silicon pulverization during lithium insertion and extraction. The findings of this study indicate that the distribution of buffer spaces, electrochemical surface area, as well as Li diffusion property significantly influence cycle performance and rate capability of the battery, which can be extended to other silicon-based anodes to overcome large volume expansion. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. From Nanostructure to Nano Biosensor: Institute of Nano Electronic Engineering (INEE, UniMAP Experience

    Directory of Open Access Journals (Sweden)

    U Hashim

    2012-02-01

    Full Text Available Nanostructure is defined as something that has a physical dimension smaller than 100 nanometers, ranging from clusters and/or to dimensional layers of atoms. There are three most important nanostructures that are extensively studied and researched in various organizations including Institute of Nano Electronic Engineering (INEE in UniMAP. These include quantum dot, nanowire, and nanogap, which have been successfully designed and fabricated using in-house facilities available. These are subsequently used as a main sensing component in nanostructures based biosensor. This fabrication, characterization and testing job were done within four main interlinked laboratories namely microfabrication cleanroom, nanofabrication cleanroom, failure analysis laboratory and nano biochip laboratory.  Currently, development of Nano Biosensor is the main research focus in INEE. In principle, biosensor is an analytical device which converts a biological response into an electrical signal.   Keywords: Nanostructure, INEE , nanowire , nanogap and Nano Biosensor

  15. Synthesis engineering of iron oxide raspberry-shaped nanostructures.

    Science.gov (United States)

    Gerber, O; Pichon, B P; Ihiawakrim, D; Florea, I; Moldovan, S; Ersen, O; Begin, D; Grenèche, J-M; Lemonnier, S; Barraud, E; Begin-Colin, S

    2017-01-07

    Magnetic porous nanostructures consisting of oriented aggregates of iron oxide nanocrystals display very interesting properties such as a lower oxidation state of magnetite, and enhanced saturation magnetization in comparison with individual nanoparticles of similar sizes and porosity. However, the formation mechanism of these promising nanostructures is not well understood, which hampers the fine tuning of their magnetic properties, for instance by doping them with other elements. Therefore the formation mechanism of porous raspberry shaped nanostructures (RSNs) synthesized by a one-pot polyol solvothermal method has been investigated in detail from the early stages by using a wide panel of characterization techniques, and especially by performing original in situ HR-TEM studies in temperature. A time-resolved study showed the intermediate formation of an amorphous iron alkoxide phase with a plate-like lamellar structure (PLS). Then, the fine investigation of PLS transformation upon heating up to 500 °C confirmed that the synthesis of RSNs involves two iron precursors: the starting one (hydrated iron chlorides) and the in situ formed iron alkoxide precursor which decomposes with time and heating and contributes to the growth step of nanostructures. Such an understanding of the formation mechanism of RSNs is necessary to envision efficient and rational enhancement of their magnetic properties.

  16. Inverse design engineering of all-silicon polarization beam splitters

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn; Sigmund, Ole

    2016-01-01

    Utilizing the inverse design engineering method of topology optimization, we have realized high-performing all-silicon ultra-compact polarization beam splitters. We show that the device footprint of the polarization beam splitter can be as compact as similar to 2 µm2 while performing experimentally...... with a polarization splitting loss lower than similar to 0.82 dB and an extinction ratio larger than similar to 15 dB in the C-band. We investigate the device performance as a function of the device length and find a lower length above which the performance only increases incrementally. Imposing a minimum feature...

  17. Hot-Spot Engineering in 3D Multi-Branched Nanostructures

    DEFF Research Database (Denmark)

    Chirumamilla, Manohar; Chirumamilla, Anisha; Roberts, Alexander

    2017-01-01

    The detection of probe molecules at ultralow concentrations, even at the single-molecule level, can be addressed with the breakthrough concept of plasmonic hot-spot engineering. In view of that, the fabrication of nanostructures endowed with sub-10 nm gaps and extremely large near-field enhanceme...

  18. Analysis of electronic parameters of nanostructure copper doped cadmium oxide/p-silicon heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Karatas, Suekrue, E-mail: skaratas@ksu.edu.tr [Department of Physics, Faculty of Science, Suetcue Imam University, Karamanmaras (Turkey); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Science, Firat University, Elazig (Turkey)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer The copper doped cadmium oxide (CdO) heterojunction diodes were fabricated by sol-gel method. Black-Right-Pointing-Pointer The electrical properties of Cu doped CdO/p-Si heterojunction diode have been investigated. Black-Right-Pointing-Pointer A strong effect of the Cu-doped content on the I-V characteristics of the diodes was found. Black-Right-Pointing-Pointer It is evaluated that the electrical performance of the CdO/p-Si diode can be controlled by Cu doped. - Abstract: The nanostructure Cu-doped CdO thin film was grown on p-type silicon substrate by sol-gel method. An Al/Cu doped CdO/p-Si heterojunction diode was fabricated. The values of ideality factor and barrier height for the Al/n-type CdO/p-Si heterojunction were obtained as 5.99 and 0.69 eV, respectively. A modified Norde function combined with conventional forward I-V method was used to extract the junction parameters including the ideality factor, barrier height and series resistance. Norde function was compared with the Cheung functions and it is seen that there is a good agreement with both method for the series resistance values. Furthermore, the interface state density (N{sub SS}) as a function of energy distribution (E{sub SS} - E{sub V}) was extracted from the forward-bias I-V measurements by taking into account the bias dependence of the effective barrier height and series resistance.

  19. Noise induced regularity of porous silicon nanostructures electrochemically etched in the presence of a sub-threshold periodic signal

    Science.gov (United States)

    Roy, Tanushree; Rumandla, Sravya; Agarwal, V.; Parmananda, P.

    2017-09-01

    In the present work, regularity of the pores generated during the electrochemical etching of silicon wafer is analyzed. The wafer-electrolyte (ethanolic hydrofluoric acid) composite is placed in an electrochemical cell operated galvanostatically at a fixed (set-point) anodic current. This set-point current is subsequently perturbed by a sub-threshold periodic current signal. Numerous experiments were performed for diverse experimental configurations. Some of the experimental parameters varied were hydrofluoric concentration, set-points, and the properties of the input periodic signal (i.e., duty cycle and amplitude). The regularity of the generated pore size distribution was quantified by calculating the spatial normalized variance (NV). For certain experimental configurations, as described later, the phenomena of Periodic Stochastic Resonance (PSR) could be provoked. In PSR, enhanced regularity of the Porous Silicon nanostructures for an optimal HF concentration is observed. Consequently, the spatial NV versus the HF concentration curve exhibits a unimodal profile.

  20. Correlating the silicon surface passivation to the nanostructure of low-temperature a-Si:H after rapid thermal annealing

    Science.gov (United States)

    Macco, Bart; Melskens, Jimmy; Podraza, Nikolas J.; Arts, Karsten; Pugh, Christopher; Thomas, Owain; Kessels, Wilhelmus M. M.

    2017-07-01

    Using an inductively coupled plasma, hydrogenated amorphous silicon (a-Si:H) films have been prepared at very low temperatures (advantage of the low-temperature approach is the facile suppression of undesired epitaxial growth. The correlation between the a-Si:H nanostructure and the activation of a-Si:H/c-Si interface passivation, upon annealing, has been studied in detail. This yields a structural model that qualitatively describes the different processes that take place in the a-Si:H films during annealing. The presented experimental findings and insights can prove to be useful in the further development of very thin a-Si:H passivation layers for use in silicon heterojunction solar cells.

  1. Less common applications of monoliths: V. Monolithic scaffolds modified with nanostructures for chromatographic separations and tissue engineering.

    Science.gov (United States)

    Krenkova, Jana; Foret, Frantisek; Svec, Frantisek

    2012-06-01

    Scaffolds modified with nanostructures are recently finding use in a broad range of applications spanning from chromatographic separations to tissue engineering. This continuation of the review series on design and applications of monolithic materials covers some of the less common monoliths including use of nanostructures in preparation, modifications, and applications. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Electrochemical synthesis of MoS2 quantum dots embedded nanostructured porous silicon with enhanced electroluminescence property

    Science.gov (United States)

    Shrivastava, Megha; Kumari, Reeta; Parra, Mohammad Ramzan; Pandey, Padmini; Siddiqui, Hafsa; Haque, Fozia Z.

    2017-11-01

    In this report we present the successful enhancement in electroluminescence (EL) in nanostructured n-type porous silicon (PS) with an idea of embedding luminophorous Molybdenum disulfide (MoS2) quantum dots (QD's). Electrochemical anodization technique was used for the formation of PS surface and MoS2 QD's were prepared using the electrochemical route. Spin coating technique was employed for the proper incorporation of MoS2 QD's within the PS nanostructures. The crystallographic analysis was performed using X-ray diffraction (XRD), Raman and Fourier transform infrared (FT-IR) spectroscopy techniques. However, surface morphology was determined using Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). The optical measurements were performed on photoluminescence (PL) spectrophotometer; additionally for electroluminescence (EL) study special arrangement of instrumental setup was made at laboratory level which provides novelty to this work. A diode prototype was made comprising Ag/MoS2:PS/Silicon/Ag for EL study. The MoS2:PS shows a remarkable concentration dependent enhancement in PL as well as in EL intensities, which paves a way to better utilize this strategy in optoelectronic device applications.

  3. Tuning cell adhesion by direct nanostructuring silicon into cell repulsive/adhesive patterns

    Energy Technology Data Exchange (ETDEWEB)

    Premnath, Priyatha, E-mail: priyatha.premnath@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Tavangar, Amirhossein, E-mail: atavanga@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Tan, Bo, E-mail: tanbo@ryerson.ca [Nanocharacterization Laboratory, Department of Aerospace Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Venkatakrishnan, Krishnan, E-mail: venkat@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada)

    2015-09-10

    Developing platforms that allow tuning cell functionality through incorporating physical, chemical, or mechanical cues onto the material surfaces is one of the key challenges in research in the field of biomaterials. In this respect, various approaches have been proposed and numerous structures have been developed on a variety of materials. Most of these approaches, however, demand a multistep process or post-chemical treatment. Therefore, a simple approach would be desirable to develop bio-functionalized platforms for effectively modulating cell adhesion and consequently programming cell functionality without requiring any chemical or biological surface treatment. This study introduces a versatile yet simple laser approach to structure silicon (Si) chips into cytophobic/cytophilic patterns in order to modulate cell adhesion and proliferation. These patterns are fabricated on platforms through direct laser processing of Si substrates, which renders a desired computer-generated configuration into patterns. We investigate the morphology, chemistry, and wettability of the platform surfaces. Subsequently, we study the functionality of the fabricated platforms on modulating cervical cancer cells (HeLa) behaviour. The results from in vitro studies suggest that the nanostructures efficiently repel HeLa cells and drive them to migrate onto untreated sites. The study of the morphology of the cells reveals that cells evade the cytophobic area by bending and changing direction. Additionally, cell patterning, cell directionality, cell channelling, and cell trapping are achieved by developing different platforms with specific patterns. The flexibility and controllability of this approach to effectively structure Si substrates to cell-repulsive and cell-adhesive patterns offer perceptible outlook for developing bio-functionalized platforms for a variety of biomedical devices. Moreover, this approach could pave the way for developing anti-cancer platforms that selectively repel

  4. Interface engineering of Graphene-Silicon heterojunction solar cells

    Science.gov (United States)

    Xu, Dikai; Yu, Xuegong; Yang, Lifei; Yang, Deren

    2016-11-01

    Graphene has attracted great research interests due to its unique mechanical, electrical and optical properties, which opens up a huge number of opportunities for applications. Recently, Graphene-Silicon (Grsbnd Si) solar cell has been recognized as one interesting candidate for the future photovoltaic. Since the first Grsbnd Si solar cell reported in 2010, Grsbnd Si solar cell has been intensively investigated and the power converse efficiency (PCE) of it has been developed to 15.6%. This review presents and discusses current development of Grsbnd Si solar cell. Firstly, the basic concept and mechanism of Grsbnd Si solar cell are introduced. Then, several key technologies are introduced to improve the performance of Grsbnd Si solar cells, such as chemical doping, annealing, Si surface passivation and interlayer insertion. Particular emphasis is placed on strategies for Grsbnd Si interface engineering. Finally, new pathways and opportunities of "MIS-like structure" Grsbnd Si solar cells are described.

  5. Gold nanostructure-integrated silica-on-silicon waveguide for the detection of antibiotics in milk and milk products

    Science.gov (United States)

    Ozhikandathil, Jayan; Badilescu, Simona; Packirisamy, Muthukumaran

    2012-10-01

    Antibiotics are extensively used in veterinary medicine for the treatment of infectious diseases. The use of antibiotics for the treatment of animals used for food production raised the concern of the public and a rapid screening method became necessary. A novel approach of detection of antibiotics in milk is reported in this work by using an immunoassay format and the Localized Surface Plasmon Resonance property of gold. An antibiotic from the penicillin family that is, ampicillin is used for testing. Gold nanostructures deposited on a glass substrate by a novel convective assembly method were heat-treated to form a nanoisland morphology. The Au nanostructures were functionalized and the corresponding antibody was absorbed from a solution. Solutions with known concentrations of antigen (antibiotics) were subsequently added and the spectral changes were monitored step by step. The Au LSPR band corresponding to the nano-island structure was found to be suitable for the detection of the antibody antigen interaction. The detection of the ampicillin was successfully demonstrated with the gold nano-islands deposited on glass substrate. This process was subsequently adapted for the integration of gold nanostructures on the silica-on-silicon waveguide for the purpose of detecting antibiotics.

  6. Imaging of buried phosphorus nanostructures in silicon using scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oberbeck, Lars [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); TOTAL Marketing Services, New Energies, La Défense 10, 92069 Paris La Défense Cedex (France); Reusch, Thilo C. G.; Hallam, Toby; Simmons, Michelle Y., E-mail: n.curson@ucl.ac.uk, E-mail: michelle.simmons@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Schofield, Steven R. [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); London Centre for Nanotechnology, UCL, London WC1H 0AH (United Kingdom); Department of Physics and Astronomy, UCL, London WC1E 6BT (United Kingdom); Curson, Neil J., E-mail: n.curson@ucl.ac.uk, E-mail: michelle.simmons@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); London Centre for Nanotechnology, UCL, London WC1H 0AH (United Kingdom); Department of Electronic and Electrical Engineering, UCL, London WC1E 7JE (United Kingdom)

    2014-06-23

    We demonstrate the locating and imaging of single phosphorus atoms and phosphorus dopant nanostructures, buried beneath the Si(001) surface using scanning tunneling microscopy. The buried dopant nanostructures have been fabricated in a bottom-up approach using scanning tunneling microscope lithography on Si(001). We find that current imaging tunneling spectroscopy is suited to locate and image buried nanostructures at room temperature and with residual surface roughness present. From these studies, we can place an upper limit on the lateral diffusion during encapsulation with low-temperature Si molecular beam epitaxy.

  7. Imaging of buried phosphorus nanostructures in silicon using scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Oberbeck, Lars; Reusch, Thilo C. G.; Hallam, Toby; Simmons, Michelle Y.; Schofield, Steven R.; Curson, Neil J.

    2014-01-01

    We demonstrate the locating and imaging of single phosphorus atoms and phosphorus dopant nanostructures, buried beneath the Si(001) surface using scanning tunneling microscopy. The buried dopant nanostructures have been fabricated in a bottom-up approach using scanning tunneling microscope lithography on Si(001). We find that current imaging tunneling spectroscopy is suited to locate and image buried nanostructures at room temperature and with residual surface roughness present. From these studies, we can place an upper limit on the lateral diffusion during encapsulation with low-temperature Si molecular beam epitaxy.

  8. Silicon nanostructures-induced photoelectrochemical solar water splitting for energy applications

    Science.gov (United States)

    Dadwal, U.; Ranjan, Neha; Singh, R.

    2016-05-01

    We study the photoelectrochemical (PEC) solar water splitting assisted with synthesized nanostructures. Si nanowires decorated with silver dendrite nanostructures have been synthesized using metal assisted wet chemical etching of (100) Si wafer. Etching has been carried out in an aqueous solution consisting of 5M HF and 0.02M AgNO3. Investigations showed that such type of semiconductor nanostructures act as efficient working electrodes for the splitting of normal water in PEC method. An enhancement in the photon-to-current conversion efficiency and solar-to-hydrogen evolution was observed for obtaining a practical source of clean and renewable fuel.

  9. Engineering plasmonic nanostructured surfaces by pulsed laser deposition

    Science.gov (United States)

    Ghidelli, Matteo; Mascaretti, Luca; Bricchi, Beatrice Roberta; Zapelli, Andrea; Russo, Valeria; Casari, Carlo Spartaco; Li Bassi, Andrea

    2018-03-01

    The synthesis and the optical response of gold nanoparticles (NPs) and thin nanostructured films grown by pulsed laser deposition (PLD) are here studied. Different PLD process parameters - including background gas pressure and the number of laser shots as well as post-deposition annealing treatments - have been varied to control the growth of Au NPs and films, thus tuning the surface plasmon characteristics. The mechanisms of NPs and film growth have been explored performing a morphological characterization by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), and the correlation with the optical behavior is investigated. We show that the size distribution and the morphology of the as deposited Au NPs depend on growth mechanisms which are controlled by tuning the deposition process, while the optical behavior is strongly affected by the average size and surface density of NPs or by the length of percolated Au domains. Furthermore, nucleation in gas phase has been reported at high (1000 Pa Ar) background pressures, enabling independent control of NP size and coverage, contrary to surface driven NP growth by diffusion and aggregation on substrate.

  10. Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seok Woo; /Stanford U., Geballe Lab.; Lee, Hyun-Wook; /Stanford U., Materials Sci. Dept.; Ryu, Ill; /Brown U.; Nix, William D.; /Stanford U., Materials Sci. Dept.; Gao, Huajian; /Brown U.; Cui, Yi; /Stanford U., Materials Sci. Dept. /SLAC

    2015-06-01

    Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Herein, we demonstrate physical/mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-76SF00515. SLAC-PUB-16300 2 lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high performance Li-ion batteries.

  11. Metal-like self-organization of periodic nanostructures on silicon and silicon carbide under femtosecond laser pulses

    International Nuclear Information System (INIS)

    Gemini, Laura; Hashida, Masaki; Shimizu, Masahiro; Miyasaka, Yasuhiro; Inoue, Shunsuke; Tokita, Shigeki; Sakabe, Shuji; Limpouch, Jiri; Mocek, Tomas

    2013-01-01

    Periodic structures were generated on Si and SiC surfaces by irradiation with femtosecond laser pulses. Self-organized structures with spatial periodicity of approximately 600 nm appear on silicon and silicon carbide in the laser fluence range just above the ablation threshold and upon irradiation with a large number of pulses. As in the case of metals, the dependence of the spatial periodicity on laser fluence can be explained by the parametric decay of laser light into surface plasma waves. The results show that the proposed model might be universally applicable to any solid state material

  12. Separation followed by direct SERS detection of explosives on a novel black silicon multifunctional nanostructured surface prepared in a microfluidic channel

    DEFF Research Database (Denmark)

    Talian, Ivan; Hübner, Jörg

    2013-01-01

    The article describes the multifunctionality of a novel black silicon (BS) nanostructured surface covered with a thin layer of noble metal prepared in the a microfluidic channel. It is focused on the separation properties of the BS substrate with direct detection of the separated analytes utilizing...

  13. Carbon Nanostructure of Diesel Soot Particles Emitted from 2 and 4 Stroke Marine Engines Burning Different Fuels.

    Science.gov (United States)

    Lee, Won-Ju; Park, Seul-Hyun; Jang, Se-Hyun; Kim, Hwajin; Choi, Sung Kuk; Cho, Kwon-Hae; Cho, Ik-Soon; Lee, Sang-Min; Choi, Jae-Hyuk

    2018-03-01

    Diesel soot particles were sampled from 2-stroke and 4-stroke engines that burned two different fuels (Bunker A and C, respectively), and the effects of the engine and fuel types on the structural characteristics of the soot particle were analyzed. The carbon nanostructures of the sampled particles were characterized using various techniques. The results showed that the soot sample collected from the 4-stroke engine, which burned Bunker C, has a higher degree of order of the carbon nanostructure than the sample collected from the 2-stroke engine, which burned Bunker A. Furthermore, the difference in the exhaust gas temperatures originating from the different engine and fuel types can affect the nanostructure of the soot emitted from marine diesel engines.

  14. Fabrication and Applications of Micro/Nanostructured Devices for Tissue Engineering

    KAUST Repository

    Limongi, Tania

    2016-09-02

    Nanotechnology allows the realization of new materials and devices with basic structural unit in the range of 1-100 nm and characterized by gaining control at the atomic, molecular, and supramolecular level. Reducing the dimensions of a material into the nanoscale range usually results in the change of its physiochemical properties such as reactivity, crystallinity, and solubility. This review treats the convergence of last research news at the interface of nanostructured biomaterials and tissue engineering for emerging biomedical technologies such as scaffolding and tissue regeneration. The present review is organized into three main sections. The introduction concerns an overview of the increasing utility of nanostructured materials in the field of tissue engineering. It elucidates how nanotechnology, by working in the submicron length scale, assures the realization of a biocompatible interface that is able to reproduce the physiological cell-matrix interaction. The second, more technical section, concerns the design and fabrication of biocompatible surface characterized by micro- and submicroscale features, using microfabrication, nanolithography, and miscellaneous nanolithographic techniques. In the last part, we review the ongoing tissue engineering application of nanostructured materials and scaffolds in different fields such as neurology, cardiology, orthopedics, and skin tissue regeneration.

  15. Multiple-layered effective medium approximation approach to modeling environmental effects on alumina passivated highly porous silicon nanostructured thin films measured by in-situ Mueller matrix ellipsometry

    Science.gov (United States)

    Mock, Alyssa; Carlson, Timothy; VanDerslice, Jeremy; Mohrmann, Joel; Woollam, John A.; Schubert, Eva; Schubert, Mathias

    2017-11-01

    Optical changes in alumina passivated highly porous silicon slanted columnar thin films during controlled exposure to toluene vapor are reported. Electron-beam evaporation glancing angle deposition and subsequent atomic layer deposition are utilized to deposit alumina passivated nanostructured porous silicon thin films. In-situ Mueller matrix generalized spectroscopic ellipsometry in an environmental cell is then used to determine changes in optical properties of the nanostructured thin films by inspection of individual Mueller matrix elements, each of which exhibit sensitivity to adsorption. The use of a multiple-layered effective medium approximation model allows for accurate description of the inhomogeneous nature of toluene adsorption onto alumina passivated highly porous silicon slanted columnar thin films.

  16. Swift heavy ions for materials engineering and nanostructuring

    CERN Document Server

    Avasthi, Devesh Kumar

    2011-01-01

    Ion beams have been used for decades for characterizing and analyzing materials. Now energetic ion beams are providing ways to modify the materials in unprecedented ways. This book highlights the emergence of high-energy swift heavy ions as a tool for tailoring the properties of materials with nanoscale structures. Swift heavy ions interact with materials by exciting/ionizing electrons without directly moving the atoms. This opens a new horizon towards the 'so-called' soft engineering. The book discusses the ion beam technology emerging from the non-equilibrium conditions and emphasizes the power of controlled irradiation to tailor the properties of various types of materials for specific needs.

  17. Polyelectrolyte-complex nanostructured fibrous scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Verma, Devendra; Katti, Kalpana S.; Katti, Dinesh R.

    2009-01-01

    In the current work, polyelectrolyte complex (PEC) fibrous scaffolds for tissue engineering have been synthesized and a mechanism of their formation has been investigated. The scaffolds are synthesized using polygalacturonic acid and chitosan using the freeze drying methodology. Highly interconnected pores of sizes in the range of 5-20 μm are observed in the scaffolds. The thickness of the fibers was found to be in the range of 1-2 μm. Individual fibers have a nanogranular structure as observed using AFM imaging. In these scaffolds, PEC nanoparticles assemble together at the interface of ice crystals during freeze drying process. Further investigation shows that the freezing temperature and concentration have a remarkable effect on structure of scaffolds. Biocompatibility studies show that scaffold containing chitosan, polygalacturonic acid and hydroxyapatite promotes cell adhesion and proliferation. On the other hand, cells on scaffolds fabricated without hydroxyapatite nanoparticles showed poor adhesion.

  18. Strong Photoluminescence Enhancement of Silicon Oxycarbide through Defect Engineering

    Directory of Open Access Journals (Sweden)

    Brian Ford

    2017-04-01

    Full Text Available The following study focuses on the photoluminescence (PL enhancement of chemically synthesized silicon oxycarbide (SiCxOy thin films and nanowires through defect engineering via post-deposition passivation treatments. SiCxOy materials were deposited via thermal chemical vapor deposition (TCVD, and exhibit strong white light emission at room-temperature. Post-deposition passivation treatments were carried out using oxygen, nitrogen, and forming gas (FG, 5% H2, 95% N2 ambients, modifying the observed white light emission. The observed white luminescence was found to be inversely related to the carbonyl (C=O bond density present in the films. The peak-to-peak PL was enhanced ~18 and ~17 times for, respectively, the two SiCxOy matrices, oxygen-rich and carbon-rich SiCxOy, via post-deposition passivations. Through a combinational and systematic Fourier transform infrared spectroscopy (FTIR and PL study, it was revealed that proper tailoring of the passivations reduces the carbonyl bond density by a factor of ~2.2, corresponding to a PL enhancement of ~50 times. Furthermore, the temperature-dependent and temperature-dependent time resolved PL (TDPL and TD-TRPL behaviors of the nitrogen and forming gas passivated SiCxOy thin films were investigated to acquire further insight into the ramifications of the passivation on the carbonyl/dangling bond density and PL yield.

  19. Engineering Low-Dimensional Nanostructures Towards Flexible Electronics

    Science.gov (United States)

    Byrley, Peter Samuel

    Flexible electronics have been proposed as the next generation of electronic devices. They have advantages over traditional electronics in that they use less material, are more durable and have greater versatility in their proposed applications. However, there are a variety of types of devices being developed that have specific engineering challenges. This dissertation addresses two of those challenges. The first challenge involves lowering contact resistance in MoS2 based flexible thin film transistor devices using a photochemical phase change method while the second addresses using silver nanowire networks as a replacement flexible electrode for indium tin oxide in flexible electronics. In this dissertation, a scalable method was developed for making monolayer MoS2 using ambient pressure chemical vapor deposition. These films were then characterized using spectroscopic techniques and atomic force microscopy. A photochemical phase change mechanism was then proposed to improve contact resistance in MoS2 based devices. The central hypothesis is that the controllable partial transition from a semiconducting 2H to metallic 1T phase can be realized in monolayer TMDs through photo-reduction in the presence of hole scavenging chemicals. Phase-engineering in monolayer TMDs would enable the fabrication of high-quality heterophase structures with the potential to improve carrier mobility and contact. Phase change as a result of the proposed photochemical method was confirmed using Raman spectroscopy, photoluminescence measurements, X-Ray photoelectron spectroscopy and other supporting data. Gold coated silver nanowires were then created to serve as flexible nanowire based electrodes by overcoming galvanic replacement in solution. This was confirmed using various forms of electron microscopy. The central hypothesis is that a thin gold coating will enable silver nanowire meshes to remain electrically stable in atmosphere and retain necessary low resistance values and

  20. The Interaction of Bacteria with Engineered Nanostructured Polymeric Materials: A Review

    Directory of Open Access Journals (Sweden)

    Ilaria Armentano

    2014-01-01

    Full Text Available Bacterial infections are a leading cause of morbidity and mortality worldwide. In spite of great advances in biomaterials research and development, a significant proportion of medical devices undergo bacterial colonization and become the target of an implant-related infection. We present a review of the two major classes of antibacterial nanostructured materials: polymeric nanocomposites and surface-engineered materials. The paper describes antibacterial effects due to the induced material properties, along with the principles of bacterial adhesion and the biofilm formation process. Methods for antimicrobial modifications of polymers using a nanocomposite approach as well as surface modification procedures are surveyed and discussed, followed by a concise examination of techniques used in estimating bacteria/material interactions. Finally, we present an outline of future sceneries and perspectives on antibacterial applications of nanostructured materials to resist or counteract implant infections.

  1. Deposition and characterization of nanostructured silicon-oxide containing diamond-like carbon coatings

    Czech Academy of Sciences Publication Activity Database

    Buršíková, V.; Dvořák, P.; Zajíčková, L.; Franta, D.; Janča, J.; Buršík, Jiří; Sobota, J.; Klapetek, P.; Bláhová, O.; Peřina, V.

    2007-01-01

    Roč. 1, č. 10 (2007), s. 491-495 ISSN 1842-6573 R&D Projects: GA ČR(CZ) GA202/05/0607 Institutional research plan: CEZ:AV0Z20410507 Keywords : nanostructured coatings * DLC * hardness Subject RIV: BL - Plasma and Gas Discharge Physics

  2. Two-dimensional sandwich-like Ag coated silicon-graphene-silicon nanostructures for superior lithium storage

    Science.gov (United States)

    Yao, Weiqi; Cui, Yansu; Zhan, Liang; Chen, Feng; Zhang, Yongzheng; Wang, Yanli; Song, Yan

    2017-12-01

    Two-dimensional (2D) sandwich-like Ag coated silicon-graphene-silicon (Ag@Si-rGO-Si) nanosheets are designed and synthesized as a novel anode material for superior lithium storage. The mesoporous Si nanofilm grows tightly on the two sides of reduced graphene oxide (rGO), and Ag nanoparticles with a size of 10-50 nm are further coated on the surface of porous Si nanofilm. Such unique features not only provide a short pathway for rapid Li+ diffusion and electron transportation, but also can act as a buffering effect to effectively inhibit the huge volume expansion of pure Si during the repeated lithiation/delithiation process. Meanwhile, a conductive network is constructed by the embedded graphene coupled with Ag nanoparticles to overcome the shortage of pure Si with low electrical conductivity. The resultant 2D sandwich-like Ag@Si-rGO-Si electrode exhibits a high reversible capability (1382 mAh g-1 at 0.1 A g-1 after 100 cycles), long cycle stability (952 mAh g-1 at 1 A g-1 after 500 cycles) and excellent high-rate performance (863 mAh g-1 at 2 A g-1, 565 mAh g-1 at 5 A g-1).

  3. Nanostructured Phosphorus Doped Silicon/Graphite Composite as Anode for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Huang, Shiqiang; Cheong, Ling-Zhi; Wang, Deyu; Shen, Cai

    2017-07-19

    Silicon as the potential anode material for lithium-ion batteries suffers from huge volume change (up to 400%) during charging/discharging processes. Poor electrical conductivity of silicon also hinders its long-term cycling performance. Herein, we report a two-step ball milling method to prepare nanostructured P-doped Si/graphite composite. Both P-doped Si and coated graphite improved the conductivity by providing significant transport channels for lithium ions and electrons. The graphite skin is able to depress the volume expansion of Si by forming a stable SEI film. The as-prepared composite anode having 50% P-doped Si and 50% graphite exhibits outstanding cyclability with a specific capacity of 883.4 mAh/g after 200 cycles at the current density of 200 mA/g. The cost-effective materials and scalable preparation method make it feasible for large-scale application of the P-doped Si/graphite composite as anode for Li-ion batteries.

  4. Shallow dopants in nanostructered and in isotopically engineered silicon

    Energy Technology Data Exchange (ETDEWEB)

    Stegner, Andre Rainer

    2011-01-15

    This work addressed two major topics. The first part was dedicated to the investigation of the doping properties of Si nanostructures. There, we have reported our results on Si nanoparticles with particular focus on questions concerning the atomic incorporation efficiency of dopants, their compensation by surface defects, and the change of their localization due to confinement effects. In the second part of this thesis, we have addressed several open questions concerning the spin properties of shallow acceptor states in bulk Si crystals with different isotope compositions. As far as the first part is concerned, ESR and SIMS have been used to quantitatively investigate the P doping efficiency and the interrelationship of Si-db states and P doping in freestanding Si-NCs over a wide range of diameters. Two types of Si-db defect states, the P{sub b} center and the D center, were identified, where the P{sub b} centers are found at concentrations comparable to bulk Si/SiO{sub 2} interfaces. Moreover, the incorporation of P donors and B acceptors in amorphous Si nanoparticles was demonstrated via ESR. Employing EDMR, we investigated the spin-dependent transport through Si-NC networks. The selectivity and the high sensitivity of EDMR enabled the observation of isolated neutral donor states, which exhibit a characteristic hyperfine splitting in samples with very small diameters. This opened up a possibility for the direct study of the properties of the donor wave function in Si-NCs. To this end, we have used the hyperfine splitting as a spectroscopic measure to monitor the localization of donor wave functions when going from the bulk to the nanoscale. As far as the spin properties of shallow acceptors in Si are concerned, we have addressed a number of fundamental questions concerning the line shape, the magnitude of the residual broadening and the substructure of the boron resonances observed in low-temperature EPR experiments. Performing EPR measurements on different

  5. Nanoscale contact engineering for Silicon/Silicide nanowire devices

    Science.gov (United States)

    Lin, Yung-Chen

    attributed to the high compressive stress built-in in the core/shell NW structure that retards the diffusion of the nickel atom as well as limits the volume expansion of the metal-rich phases. As a result, the high stress at this finite scale hinders the continuous growth of Ni31Si 12 into the core/shell NWs and totally eliminates the formation of Ni 2Si in core/shell NWs with thick oxide shells (˜ 50 nm). Through these studies, we have demonstrated first time the phase formation sequences of nickel silicides in Si and Si/SiOx NW structures, which is of great importance for reliable contact engineering for Si NW devices. Furthermore, we have provided a clear picture of the hindered nickel silicide growth in confined nanoscale environment and showed the deviated behavior of silicides growth under stress. The information rendered here will be useful for Si NW device applications as well as for the silicon device engineering at nanoscale in general. To further investigate the oxide shell effect, Mn5Si 3 and Fe5Ge3 NW were grown within various oxide thickness to explore the nucleation and growth in the nanowire structure. A oxide shell exerted a compressive stress on the silicide or germanide materials will make those materials with single-crystal properties. Interestingly, single-crystal growth of contact materials can be also implemented for germanide materials. The iron-rich germanide, Fe5Ge3, was successfully grown with single-crystal properties. It shows ferromagnetic properties with a Curie temperature above the room temperature verified by magnetic force microscope (MFM). Two different epitaxial relations found at germanide/germanium interface due to the different sizes of the germanium NW templates. These two different crystal structures exhibited magnetic anisotropy in magnetic force microscope (MFM) measurement, showing differently preferred domain orientations. In-plane and out-of-plane magnetization in the Fe5Ge3 NWs are observed in our experiment. The crystal

  6. Generation of silicon nanostructures by atmospheric microplasma jet: the role of hydrogen admixture

    Czech Academy of Sciences Publication Activity Database

    Barwe, B.; Stein, A.; Cibulka, Ondřej; Pelant, Ivan; Ghanbaja, J.; Belmonte, T.; Benedikt, J.

    2015-01-01

    Roč. 12, č. 2 (2015), s. 132-140 ISSN 1612-8850 Institutional support: RVO:68378271 Keywords : atmospheric pressure plasmas * HRTEM * microplasmas * photoluminescence * silicon nanocrystals Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.713, year: 2015

  7. Modal analysis of silicon nanostructured waveguide with holey cladding in 2-D isosceles triangular lattice

    NARCIS (Netherlands)

    Uranus, H.P.; Hoekstra, Hugo; Vos, Willem L.

    2009-01-01

    Silicon photonics, either in the form of integrated optical chips or fiber, has attracted much interest due to their small foot-print, high refractive-index, high thermal conductivity, high non-linear-optical coefficient, and compatibility with CMOS and fiber-drawing process technology. Recently,

  8. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Luo Guanghong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Diao Jiajie [Department of Physics, George Washington University, Washington, DC 20052 (United States); Chornoguz, Olesya [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Reeves, Mark [Department of Physics, George Washington University, Washington, DC 20052 (United States); Vertes, Akos [Department of Chemistry, George Washington University, Washington, DC 20052 (United States)

    2007-04-15

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12{+-}1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3x{omega} Nd:YAG laser in air, SF{sub 6} or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to {approx}2 {mu}m in SF{sub 6} gas and to {approx}5 {mu}m in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly ({approx}10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits.

  9. Strain-Engineering of Giant Pseudo-Magnetic Fields in Graphene/Boron Nitride (BN) Periodic Nanostructures

    Science.gov (United States)

    Hsu, Chen-Chih; Wang, Jiaqing; Teague, Marcus; Chen, Chien-Chang; Yeh, Nai-Chang

    2015-03-01

    Ideal graphene is strain-free whereas non-trivial strain can induce pseudo-magnetic fields as predicted theoretically and manifested experimentally. Here we employ nearly strain-free single-domain graphene, grown by plasma-enhanced chemical vapor deposition (PECVD) at low temperatures, to induce controlled strain by placing the PECVD-graphene on substrates containing engineered nanostructures. We fabricate periodic pyramid nanostructures (typically 100 ~ 200 nm laterally and 10 ~ 60 nm in height) on Si substrates by focused ion beam, and determine the topography of these nanostructures using atomic force microscopy and scanning electron microscopy after we transferred monolayer h-BN followed by PECVD-graphene onto these substrates. We find both layers conform well to the nanostructures so that we can control the size, arrangement, separation, and shape of the nanostructures to generate desirable pseudo-magnetic fields. We also employ molecular dynamics simulation to determine the displacement of carbon atoms under a given nanostructure. The pseudo-magnetic field thus obtained is ~150T in the center, relatively homogeneous over 50% of the area, and drops off precipitously near the edge. These findings are extended to arrays of nanostructures and compared with topographic and spectroscopic studies by STM. Supported by NSF.

  10. Modelling of the hydrogen effects on the morphogenesis of hydrogenated silicon nano-structures in a plasma reactor

    International Nuclear Information System (INIS)

    Brulin, Q.

    2006-01-01

    This work pursues the goal of understanding mechanisms related to the morphogenesis of hydrogenated silicon nano-structures in a plasma reactor through modeling techniques. Current technologies are first reviewed with an aim to understand the purpose behind their development. Then follows a summary of the possible studies which are useful in this particular context. The various techniques which make it possible to simulate the trajectories of atoms by molecular dynamics are discussed. The quantum methods of calculation of the interaction potential between chemical species are then developed, reaching the conclusion that only semi-empirical quantum methods are sufficiently fast to be able to implement an algorithm of quantum molecular dynamics on a reasonable timescale. From the tools introduced, a reflection on the nature of molecular metastable energetic states is presented for the theoretical case of the self-organized growth of a linear chain of atoms. This model - which consists of propagating the growth of a chain by the successive addition of the atom which least increases the electronic energy of the chain - shows that the Fermi level is a parameter essential to self organization during growth. This model also shows that the structure formed is not necessarily a total minimum energy structure. From all these numerical tools, the molecular growth of clusters can be simulated by using parameters from magnetohydrodynamic calculation results of plasma reactor modeling (concentrations of the species, interval between chemical reactions, energy of impact of the reagents...). The formation of silicon-hydrogen clusters is thus simulated by the successive capture of silane molecules. The structures formed in simulation at the operating temperatures of the plasma reactor predict the formation of spherical clusters constituting an amorphous silicon core covered by hydrogen. These structures are thus not in a state of minimum energy, contrary to certain experimental

  11. Scalable creation of gold nanostructures on high performance engineering polymeric substrate

    Science.gov (United States)

    Jia, Kun; Wang, Pan; Wei, Shiliang; Huang, Yumin; Liu, Xiaobo

    2017-12-01

    The article reveals a facile protocol for scalable production of gold nanostructures on a high performance engineering thermoplastic substrate made of polyarylene ether nitrile (PEN) for the first time. Firstly, gold thin films with different thicknesses of 2 nm, 4 nm and 6 nm were evaporated on a spin-coated PEN substrate on glass slide in vacuum. Next, the as-evaporated samples were thermally annealed around the glass transition temperature of the PEN substrate, on which gold nanostructures with island-like morphology were created. Moreover, it was found that the initial gold evaporation thickness and annealing atmosphere played an important role in determining the morphology and plasmonic properties of the formulated Au NPs. Interestingly, we discovered that isotropic Au NPs can be easily fabricated on the freestanding PEN substrate, which was fabricated by a cost-effective polymer solution casting method. More specifically, monodispersed Au nanospheres with an average size of ∼60 nm were obtained after annealing a 4 nm gold film covered PEN casting substrate at 220 °C for 2 h in oxygen. Therefore, the scalable production of Au NPs with controlled morphology on PEN substrate would open the way for development of robust flexible nanosensors and optical devices using high performance engineering polyarylene ethers.

  12. Sub-parts per million NO2 chemi-transistor sensors based on composite porous silicon/gold nanostructures prepared by metal-assisted etching.

    Science.gov (United States)

    Sainato, Michela; Strambini, Lucanos Marsilio; Rella, Simona; Mazzotta, Elisabetta; Barillaro, Giuseppe

    2015-04-08

    Surface doping of nano/mesostructured materials with metal nanoparticles to promote and optimize chemi-transistor sensing performance represents the most advanced research trend in the field of solid-state chemical sensing. In spite of the promising results emerging from metal-doping of a number of nanostructured semiconductors, its applicability to silicon-based chemi-transistor sensors has been hindered so far by the difficulties in integrating the composite metal-silicon nanostructures using the complementary metal-oxide-semiconductor (CMOS) technology. Here we propose a facile and effective top-down method for the high-yield fabrication of chemi-transistor sensors making use of composite porous silicon/gold nanostructures (cSiAuNs) acting as sensing gate. In particular, we investigate the integration of cSiAuNs synthesized by metal-assisted etching (MAE), using gold nanoparticles (NPs) as catalyst, in solid-state junction-field-effect transistors (JFETs), aimed at the detection of NO2 down to 100 parts per billion (ppb). The chemi-transistor sensors, namely cSiAuJFETs, are CMOS compatible, operate at room temperature, and are reliable, sensitive, and fully recoverable for the detection of NO2 at concentrations between 100 and 500 ppb, up to 48 h of continuous operation.

  13. Use of self-assembled peptide nanostructures for the fabrication of silicon nanowires

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime; Bakmand, Tania

    2011-01-01

    1. INTRODUCTION Self-assembled diphenylalanine peptide nanotubes provide a means of achieving nanostructured materials in a very simple and fast way. Recent discoveries have shown that this unique material, in addition to remaining stable under dry conditions, rapidly dissolves in water making it...... nanowires. Furthermore, the PNTs could be used as lift-off masks for the patterning during deposition of materials. REFERENCES [1] K. B. Andersen, J. Castillo-León, M. Hedstrom, W. E. Svendsen. Nanoscale. 3, 994-998, (2011)...

  14. Resonant enhancement in nanostructured thermoelectric performance via electronic thermal conductivity engineering

    Science.gov (United States)

    Patil, Urvesh; Muralidharan, Bhaskaran

    2017-01-01

    The use of an asymmetric broadening in the transport distribution, a characteristic of resonant structures, is proposed as a route to engineer a decrease in electronic thermal conductivity thereby enhancing the electronic figure of merit in nanostructured thermoelectrics. Using toy models, we first demonstrate that a decrease in thermal conductivity resulting from such an asymmetric broadening may indeed lead to an electronic figure of merit well in excess of 1000 in an idealized situation and in excess of 10 in a realistic situation. We then substantiate with realistic resonant structures designed using graphene nano-ribbons by employing a tight binding framework with edge correction that match density functional theory calculations under the local density approximation. The calculated figure of merit exceeding 10 in such realistic structures further reinforces the concept and sets a promising direction to use nano-ribbon structures to engineer a favorable decrease in the electronic thermal conductivity.

  15. Risks and health effects from exposure to engineered nanostructures: A critical review

    International Nuclear Information System (INIS)

    Nikodinovska, Violeta Vasilevska; Mladenovska, Kristina; Grozdanov, Anita

    2015-01-01

    Nanotechnology and engineered nanostructures (ENSs) are becoming part of everyday life, starting from industrial application, even in food products, to gene therapy. Thus, tons and tons of nanoparticles (NPs) enter the environment and indirectly or directly - into the biological systems, including the human body. There are many controversial papers that describe interactions of the ENSs with biological systems and raise concern that intentional or unintentional human exposure to certain types of ENSs, may lead to significant health, i.e. toxicological effects. Because of our insufficient and contradictory knowledge about the health effects associated with the ENSs exposure, the aim of this paper is to summarize and systematize the already confirmed data and the latest found facts about ENSs and their health effects and to discuss the future opportunities and tasks in the field of nanotoxicology. Keywords: engineered nano sized structures, nanotoxicology.

  16. Mechanical engineering and design of silicon-based particle tracking devices

    International Nuclear Information System (INIS)

    Miller, W.O.; Thompson, T.C.; Gamble, M.T.; Reid, R.S.; Woloshun, K.A.; Dransfield, G.D.; Ziock, H.J.

    1990-01-01

    The Mechanical Engineering and Electronics Division of the Los Alamos National Laboratory has been investigating silicon-based particle tracking device technology as part of the Superconducting Super Collider-sponsored silicon subsystem collaboration. Structural, thermal, and materials issues have been addressed. This paper discussed detector structural integrity and stability, including detailed finite element models of the silicon chip support and predictive methods used in designing with advanced composite materials. Electronic thermal loading and efficient dissipation of such energy using heat pipe technology has been investigated. The use of materials whose coefficients of thermal expansion are engineered to match silicon or to be near zero, as appropriate, have been explored. Material analysis and test results from radiation, chemical, and static loading are compared with analytical predictions and discussed. 1 ref., 2 figs., 1 tab

  17. Surface nanostructuring in the carbon–silicon(100) system upon microwave plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yafarov, R. K., E-mail: pirpc@yandex.ru; Shanygin, V. Ya. [Russian Academy of Sciences, Kotel’nikov Institute of Radio Engineering and Electronics, Saratov Branch (Russian Federation)

    2017-04-15

    The study is concerned with the physical and chemical processes and the mechanisms of the effect of plasma preparation of a surface on the systematic features of condensation and surface phase transformations during the formation of Si–C mask domains on p-Si(100) crystals by the deposition of submonolayer C coatings in the microwave plasma of low-pressure ethanol vapors. It is shown that, at short durations of the deposition of carbon onto silicon wafers with a natural-oxide coating at a temperature of 100°C, the formation of domains is observed. The lateral dimensions of the domains lie in the range from 10–15 to 200 nm, and the heights of ridges produced by the plasma chemical etching of silicon through the mask domain coatings vary in the range from 40 to 80 nm.

  18. Development of Nanosized/Nanostructured Silicon as Advanced Anodes for Lithium-Ion Cells

    Science.gov (United States)

    Wu, James J.

    2015-01-01

    NASA is developing high energy and high capacity Li-ion cell and battery designs for future exploration missions under the NASA Advanced Space Power System (ASPS) Program. The specific energy goal is 265 Wh/kg at 10 C. center dot Part of effort for NASA advanced Li-ion cells ? Anode: Silicon (Si) as an advanced anode. ? Electrolyte: advanced electrolyte with flame-retardant additives for enhanced performance and safety (NASA JPL).

  19. UV Laser Deposition of Nanostructured Si/C/O/N/H Precursor to Silicon Oxycarbonitride

    Czech Academy of Sciences Publication Activity Database

    Pola, Josef; Galíková, Anna; Bastl, Zdeněk; Šubrt, Jan; Vacek, Karel; Brus, Jiří; Ouchi, A.

    2006-01-01

    Roč. 20, č. 10 (2006), s. 648-655 ISSN 0268-2605 R&D Projects: GA MŠk(CZ) ME 684 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502; CEZ:AV0Z40400503; CEZ:AV0Z40500505 Keywords : laser photolysis * silicon oxycarbonitride * chemical vapor deposition Subject RIV: CA - Inorganic Chemistry Impact factor: 1.233, year: 2006

  20. Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide.

    Science.gov (United States)

    Shen, Boxuan; Linko, Veikko; Dietz, Hendrik; Toppari, J Jussi

    2015-01-01

    DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thiol-linkers. In general, structural deformations of the origami during the DEP trapping are highly dependent on the shape and the construction of the structure. The SQL brick turned out to be the most robust structure under the high DEP forces, and accordingly, its single-structure trapping yield was also highest. In addition, the electrical conductivity of single immobilized plain brick-like structures was characterized. The electrical measurements revealed that the conductivity is negligible (insulating behavior). However, we observed that the trapping process of the SQL brick equipped with thiol-linkers tended to induce an etched "nanocanyon" in the silicon dioxide substrate. The nanocanyon was formed exactly between the electrodes, that is, at the location of the DEP-trapped origami. The results show that the demonstrated DEP-trapping technique can be readily exploited in assembling and arranging complex multilayered origami geometries. In addition, DNA origamis could be utilized in DEP-assisted deformation of the substrates onto which they are attached. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Silicon subsystem mechanical engineering work for the solenoidal detector collaboration

    International Nuclear Information System (INIS)

    Miller, W.O.; Barney, M.; Byrd, D.; Christensen, R.W.; Dransfield, G.; Elder, M.; Gamble, M.; Crastataro, C.; Hanlon, J.; Jones, D.C.

    1995-01-01

    The silicon tracking system (STS) for the Solenoidal Detector Collaboration (SDC) represented an order of magnitude increase in size over any silicon system that had been previously built or even planned. In order to meet its performance requirements, it could not simply be a linear scaling of earlier systems, but instead required completely new concepts. The small size of the early systems made it possible to simply move the support hardware and services largely outside the active volume of the system. For a system five meters long, that simply is not an option. The design of the STS for the SDC experiment was the result of numerous compromises between the capabilities required to do the physics and the limitations imposed by cost, material properties, and silicon strip detector characteristics. From the point of view of the physics, the silicon system should start as close to the interaction point as possible. In addition, the detectors should measure the position of particles passing through them with no errors, and should not deflect or interact with the particles in any way. However, cost, radiation damage, and other factors limiting detector performance dictated, other, more realistic values. Radiation damage limited the inner radius of the silicon detectors to about 9 cm, whereas cost limited the outer radius of the detectors to about 50 cm. Cost also limits the half length of the system to about 250 cm. To control the effects of radiation damage on the detectors required operating the system at a temperature of 0 degrees C or below, and maintaining that temperature throughout life of the system. To summarize, the physics and properties of the silicon strip detectors requires that the detectors be operated at or below 0 degrees C, be positioned very accurately during assembly and remain positionally stable throughout their operation, and that all materials used be radiation hard and have a large thickness for one radiation length

  2. Three-Dimensional Silicon-Germanium Nanostructures for CMOS Compatible Light Emitters and Optical Interconnects

    Directory of Open Access Journals (Sweden)

    L. Tsybeskov

    2008-01-01

    Full Text Available Three-dimensional SiGe nanostructures grown on Si (SiGe/Si using molecular beam epitaxy or low-pressure chemical vapor deposition exhibit photoluminescence and electroluminescence in the important spectral range of 1.3–1.6 μm. At a high level of photoexcitation or carrier injection, thermal quenching of the luminescence intensity is suppressed and the previously confirmed type-II energy band alignment at Si/SiGe cluster heterointerfaces no longer controls radiative carrier recombination. Instead, a recently proposed dynamic type-I energy band alignment is found to be responsible for the strong decrease in carrier radiative lifetime and further increase in the luminescence quantum efficiency.

  3. The Luminescent Properties and Atomic Structures of As-Grown and Annealed Nanostructured Silicon Rich Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    N. D. Espinosa-Torres

    2016-01-01

    Full Text Available Not long ago, we developed a theoretical model to describe a set of chemical reactions that can potentially occur during the process of obtaining Silicon Rich Oxide (SRO films, an off stoichiometry material, notwithstanding the technique used to grow such films. In order to elucidate the physical chemistry properties of such material, we suggested the chemical reactions that occur during the process of growing of SRO films in particular for the case of the Low Pressure Chemical Vapor Deposition (LPCVD technique in the aforementioned model. The present paper represents a step further with respect to the previous (published work, since it is dedicated to the calculation by Density Functional Theory (DFT of the optical and electronic properties of the as-grown and annealed SRO structures theoretically predicted on the basis of the previous work. In this work, we suggest and evaluate either some types of molecules or resulting nanostructures and we predict theoretically, by applying the DFT, the contribution that they may have to the phenomenon of luminescence (PL, which is experimentally measured in SRO films. We evaluated the optical and electronic properties of both the as-grown and the annealed structures.

  4. Dual-Layer Nanostructured Flexible Thin-Film Amorphous Silicon Solar Cells with Enhanced Light Harvesting and Photoelectric Conversion Efficiency.

    Science.gov (United States)

    Lin, Yinyue; Xu, Zhen; Yu, Dongliang; Lu, Linfeng; Yin, Min; Tavakoli, Mohammad Mahdi; Chen, Xiaoyuan; Hao, Yuying; Fan, Zhiyong; Cui, Yanxia; Li, Dongdong

    2016-05-04

    Three-dimensional (3-D) structures have triggered tremendous interest for thin-film solar cells since they can dramatically reduce the material usage and incident light reflection. However, the high aspect ratio feature of some 3-D structures leads to deterioration of internal electric field and carrier collection capability, which reduces device power conversion efficiency (PCE). Here, we report high performance flexible thin-film amorphous silicon solar cells with a unique and effective light trapping scheme. In this device structure, a polymer nanopillar membrane is attached on top of a device, which benefits broadband and omnidirectional performances, and a 3-D nanostructure with shallow dent arrays underneath serves as a back reflector on flexible titanium (Ti) foil resulting in an increased optical path length by exciting hybrid optical modes. The efficient light management results in 42.7% and 41.7% remarkable improvements of short-circuit current density and overall efficiency, respectively. Meanwhile, an excellent flexibility has been achieved as PCE remains 97.6% of the initial efficiency even after 10 000 bending cycles. This unique device structure can also be duplicated for other flexible photovoltaic devices based on different active materials such as CdTe, Cu(In,Ga)Se2 (CIGS), organohalide lead perovskites, and so forth.

  5. Defects and impurities in silicon materials an introduction to atomic-level silicon engineering

    CERN Document Server

    Langouche, Guido

    2015-01-01

    This book emphasizes the importance of the fascinating atomistic insights into the defects and the impurities as well as the dynamic behaviors in silicon materials, which have become more directly accessible over the past 20 years. Such progress has been made possible by newly developed experimental methods, first principle theories, and computer simulation techniques. The book is aimed at young researchers, scientists, and technicians in related industries. The main purposes are to provide readers with 1) the basic physics behind defects in silicon materials, 2) the atomistic modeling as well as the characterization techniques related to defects and impurities in silicon materials, and 3) an overview of the wide range of the research fields involved.

  6. Influence of irradiation dose on laser-induced surface nanostructures on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Varlamova, Olga [Brandenburgische Technische Universität BTU Cottbus, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Cottbus JointLab, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Bounhalli, Mourad [Brandenburgische Technische Universität BTU Cottbus, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Laboratoire Hubert Curien, Université St. Etienne, Bâtiment F 18 Rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Reif, Juergen, E-mail: REIF@TU-COTTBUS.DE [Brandenburgische Technische Universität BTU Cottbus, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Cottbus JointLab, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany)

    2013-08-01

    We report on the dependence of femtosecond laser-induced periodic surface structures on an increase of incident pulse number. On silicon, the patterns evolve from linear, parallel sub-wavelength ripples, grossly perpendicular to the laser polarization, via coalesced wider features parallel to the polarization, to a crater with periodically structured, pillar-like walls. Closer inspection of the patterns indicates that the different features always continue to exhibit reminiscence to the preceding lower-dose patterns, suggesting that, indeed, all patterns can be created by ONE single GENERAL formation process, as in self-organized structure formation, and the different structures/feature sizes are NOT due to DIFFERENT mechanisms.

  7. Influence of irradiation dose on laser-induced surface nanostructures on silicon

    International Nuclear Information System (INIS)

    Varlamova, Olga; Bounhalli, Mourad; Reif, Juergen

    2013-01-01

    We report on the dependence of femtosecond laser-induced periodic surface structures on an increase of incident pulse number. On silicon, the patterns evolve from linear, parallel sub-wavelength ripples, grossly perpendicular to the laser polarization, via coalesced wider features parallel to the polarization, to a crater with periodically structured, pillar-like walls. Closer inspection of the patterns indicates that the different features always continue to exhibit reminiscence to the preceding lower-dose patterns, suggesting that, indeed, all patterns can be created by ONE single GENERAL formation process, as in self-organized structure formation, and the different structures/feature sizes are NOT due to DIFFERENT mechanisms.

  8. Experimental Demonstration of Phase Sensitive Parametric Processes in a Nano-Engineered Silicon Waveguide

    DEFF Research Database (Denmark)

    Kang, Ning; Fadil, Ahmed; Pu, Minhao

    2013-01-01

    We demonstrate experimentally phase-sensitive processes in nano-engineered silicon waveguides for the first time. Furthermore, we highlight paths towards the optimization of the phase-sensitive extinction ratio under the impact of two-photon and free-carrier absorption.......We demonstrate experimentally phase-sensitive processes in nano-engineered silicon waveguides for the first time. Furthermore, we highlight paths towards the optimization of the phase-sensitive extinction ratio under the impact of two-photon and free-carrier absorption....

  9. Analytical and Experimental Evaluation of Joining Silicon Carbide to Silicon Carbide and Silicon Nitride to Silicon Nitride for Advanced Heat Engine Applications Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Sundberg, G.J.

    1994-01-01

    Techniques were developed to produce reliable silicon nitride to silicon nitride (NCX-5101) curved joins which were used to manufacture spin test specimens as a proof of concept to simulate parts such as a simple rotor. Specimens were machined from the curved joins to measure the following properties of the join interlayer: tensile strength, shear strength, 22 C flexure strength and 1370 C flexure strength. In parallel, extensive silicon nitride tensile creep evaluation of planar butt joins provided a sufficient data base to develop models with accurate predictive capability for different geometries. Analytical models applied satisfactorily to the silicon nitride joins were Norton's Law for creep strain, a modified Norton's Law internal variable model and the Monkman-Grant relationship for failure modeling. The Theta Projection method was less successful. Attempts were also made to develop planar butt joins of siliconized silicon carbide (NT230).

  10. Surface design and engineering of hierarchical hybrid nanostructures for asymmetric supercapacitors with improved electrochemical performance.

    Science.gov (United States)

    Achilleos, Demetra S; Hatton, T Alan

    2015-06-01

    With the current rising world demand for energy sufficiency, there is an increased necessity for the development of efficient energy storage devices. To address these needs, the scientific community has focused on the improvement of the electrochemical properties of the most well known energy storage devices; the Li-ion batteries and electrochemical capacitors, also called supercapacitors. Despite the fact that supercapacitors exhibit high power densities, good reversibility and long cycle life, they still exhibit lower energy densities than batteries, which limit their practical application. Various strategies have been employed to circumvent this problem, specifically targetting an increase in the specific capacitance and the broadening of the potential window of operation of these systems. In recent years, sophisticated surface design and engineering of hierarchical hybrid nanostructures has facilitated significant improvements in the specific and volumetric storage capabilities of supercapacitors. These nanostructured electrodes exhibit higher surface areas for ion adsorption and reduced ion diffusion lengths for the electrolyte ions. Significant advances have also been achieved in broadening the electrochemical window of operation of these systems, as realized via the development of asymmetric two-electrode cells consisting of nanocomposite positive and negative electrodes with complementary electrochemical windows, which operate in environmentally benign aqueous media. We provide an overview of the diverse approaches, in terms of chemistry and nanoscale architecture, employed recently for the development of asymmetric supercapacitors of improved electrochemical performance. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Adsorption of small NaCl clusters on surfaces of silicon nanostructures

    International Nuclear Information System (INIS)

    Amsler, Maximilian; Alireza Ghasemi, S; Goedecker, Stefan; Neelov, Alexey; Genovese, Luigi

    2009-01-01

    We have studied possible adsorption geometries of neutral NaCl clusters on the disordered surface of a large silicon model tip used in non-contact atomic force microscopy. The minima hopping method was used to determine low energy model tip configurations as well as ground state geometries of isolated NaCl clusters. The combined system was treated with density functional theory. Alkali halides have proven to be strong structure seekers and tend to form highly stable ground state configurations whenever possible. The favored adsorption geometry for four Na and four Cl atoms was found to be an adsorption of four NaCl dimers due to the formation of Cl-Si bonds. However, for larger NaCl clusters, the increasing energy required to dissociate the cluster into NaCl dimers suggests that adsorption of whole clusters in their isolated ground state configuration is preferred.

  12. Wettability behaviour of RTV silicone rubber coated on nanostructured aluminium surface

    Science.gov (United States)

    Momen, Gelareh; Farzaneh, Masoud; Jafari, Reza

    2011-05-01

    A nanostructutered superhydrophobic surface was elaborated by applying an RTV silicone rubber coating on electrochemically processed aluminium substrates. Study of anodisation voltage on surface morphology showed that higher anodising voltage led to larger pore sizes. Scanning electron microscopy image analysis showed bird's nest and beehive structures formed on anodised surfaces at 50 V and 80 V. Water static contact angle on the treated surfaces reached up to 160° at room temperature. Study of superhydrophobic surfaces at super cooled temperature showed important delayed freezing time for RTV hydrophobic surfaces when compared to non-treated aluminium. However, lower wettability was observed when surface temperature went down from 20 °C to -10 °C. Also, it was found that the capacitance of superhydrophobic surfaces decreased with increasing anodising voltage.

  13. Polymer functionalized nanostructured porous silicon for selective water vapor sensing at room temperature

    Science.gov (United States)

    Dwivedi, Priyanka; Das, Samaresh; Dhanekar, Saakshi

    2017-04-01

    This paper highlights the surface treatment of porous silicon (PSi) for enhancing the sensitivity of water vapors at room temperature. A simple and low cost technique was used for fabrication and functionalization of PSi. Spin coated polyvinyl alcohol (PVA) was used for functionalizing PSi surface. Morphological and structural studies were conducted to analyze samples using SEM and XRD/Raman spectroscopy respectively. Contact angle measurements were performed for assessing the wettability of the surfaces. PSi and functionalized PSi samples were tested as sensors in presence of different analytes like ethanol, acetone, isopropyl alcohol (IPA) and water vapors in the range of 50-500 ppm. Electrical measurements were taken from parallel aluminium electrodes fabricated on the functionalized surface, using metal mask and thermal evaporation. Functionalized PSi sensors in comparison to non-functionalized sensors depicted selective and enhanced response to water vapor at room temperature. The results portray an efficient and selective water vapor detection at room temperature.

  14. Plasmonic Nanostructure for Enhanced Light Absorption in Ultrathin Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Jinna He

    2012-01-01

    Full Text Available The performances of thin film solar cells are considerably limited by the low light absorption. Plasmonic nanostructures have been introduced in the thin film solar cells as a possible solution around this issue in recent years. Here, we propose a solar cell design, in which an ultrathin Si film covered by a periodic array of Ag strips is placed on a metallic nanograting substrate. The simulation results demonstrate that the designed structure gives rise to 170% light absorption enhancement over the full solar spectrum with respect to the bared Si thin film. The excited multiple resonant modes, including optical waveguide modes within the Si layer, localized surface plasmon resonance (LSPR of Ag stripes, and surface plasmon polaritons (SPP arising from the bottom grating, and the coupling effect between LSPR and SPP modes through an optimization of the array periods are considered to contribute to the significant absorption enhancement. This plasmonic solar cell design paves a promising way to increase light absorption for thin film solar cell applications.

  15. Impacts of fuel formulation and engine operating parameters on the nanostructure and reactivity of diesel soot

    Science.gov (United States)

    Yehliu, Kuen

    This study focuses on the impacts of fuel formulations on the reactivity and nanostructure of diesel soot. A 2.5L, 4-cylinder, turbocharged, common rail, direct injection light-duty diesel engine was used in generating soot samples. The impacts of engine operating modes and the start of combustion on soot reactivity were investigated first. Based on preliminary investigations, a test condition of 2400 rpm and 64 Nm, with single and split injection strategies, was chosen for studying the impacts of fuel formulation on the characteristics of diesel soot. Three test fuels were used: an ultra low sulfur diesel fuel (BP15), a pure soybean methyl-ester (B100), and a synthetic Fischer-Tropsch fuel (FT) produced in a gas-to-liquid process. The start of injection (SOI) and fuel rail pressures were adjusted such that the three test fuels have similar combustion phasing, thereby facilitating comparisons between soots from the different fuels. Soot reactivity was investigated by thermogravimetric analysis (TGA). According to TGA, B100 soot exhibits the fastest oxidation on a mass basis followed by BP15 and FT derived soots in order of apparent rate constant. X-ray photoelectron spectroscopy (XPS) indicates no relation between the surface oxygen content and the soot reactivity. Crystalline information for the soot samples was obtained using X-ray diffraction (XRD). The basal plane diameter obtained from XRD was inversely related to the apparent rate constants for soot oxidation. For comparison, high resolution transmission electron microscopy (HRTEM) provided images of the graphene layers. Quantitative image analysis proceeded by a custom algorithm. B100 derived soot possessed the shortest mean fringe length and greatest mean fringe tortuosity. This suggests soot (nano)structural disorder correlates with a faster oxidation rate. Such results are in agreement with the X-ray analysis, as the observed fringe length is a measure of basal plane diameter. Moreover the relation

  16. Dynamic response of silicon nanostructures at finite frequency: An orbital-free density functional theory and non-equilibrium Green's function study

    Science.gov (United States)

    Xu, Fuming; Wang, Bin; Wei, Yadong; Wang, Jian

    2013-10-01

    Orbital-free density functional theory (OFDFT) replaces the wavefunction in the kinetic energy by an explicit energy functional and thereby speeds up significantly the calculation of ground state properties of the solid state systems. So far, the application of OFDFT has been centered on closed systems and less attention is paid on the transport properties in open systems. In this paper, we use OFDFT and combine it with non-equilibrium Green's function to simulate equilibrium electronic transport properties in silicon nanostructures from first principles. In particular, we study ac transport properties of a silicon atomic junction consisting of a silicon atomic chain and two monoatomic leads. We have calculated the dynamic conductance of this atomic junction as a function of ac frequency with one to four silicon atoms in the central scattering region. Although the system is transmissive with dc conductance around 4 to 5 e2/h, capacitive-like behavior was found in the finite frequency regime. Our analysis shows that, up to 0.1 THz, this behavior can be characterized by a classic RC circuit consisting of two resistors and a capacitor. One resistor gives rise to dc resistance and the other one accounts for the charge relaxation resistance with magnitude around 0.2 h/e2 when the silicon chain contains two atoms. It was found that the capacitance is around 5 aF for the same system.

  17. Infrared spectroscopy of one-dimensional metallic nanostructures on silicon vicinal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, Chung Vu

    2010-06-23

    Vicinal silicon(111) surfaces are used as templates for the growth of lead nanowires as well as gold and indium atom chains. The morphology of the Au atom chains was studied by use of Scanning Tunneling Microscopy (STM) and Reflection High Energy Electron Diffraction (RHEED). The In chains were investigated by infrared spectroscopy with the electrical field component of the IR light polarized either parallel or perpendicular to the wires. It is shown that at room temperature, In atom-chains display a plasmonic absorption feature along the chain but not in the perpendicular direction. Furthermore, upon cooling down to liquid nitrogen temperature, a metal to insulator transition is observed. A structural distortion is also confirmed by RHEED. As for the result of Pb nanowires, by means of infrared spectroscopy, it is now possible to control the average length of parallel nanowire arrays by monitoring four experimental parameters that influence on the nucleation density; namely: Pb coverage, evaporation rate, substrate temperature and the surface itself. The system shows an enhancement of the absorption at the antenna frequency in the low temperature regime. This scenario is assigned to the reduction of electron-phonon scattering due to low temperature. (orig.)

  18. Discovery of gigantic molecular nanostructures using a flow reaction array as a search engine.

    Science.gov (United States)

    Zang, Hong-Ying; de la Oliva, Andreu Ruiz; Miras, Haralampos N; Long, De-Liang; McBurney, Roy T; Cronin, Leroy

    2014-04-28

    The discovery of gigantic molecular nanostructures like coordination and polyoxometalate clusters is extremely time-consuming since a vast combinatorial space needs to be searched, and even a systematic and exhaustive exploration of the available synthetic parameters relies on a great deal of serendipity. Here we present a synthetic methodology that combines a flow reaction array and algorithmic control to give a chemical 'real-space' search engine leading to the discovery and isolation of a range of new molecular nanoclusters based on [Mo(2)O(2)S(2)](2+)-based building blocks with either fourfold (C4) or fivefold (C5) symmetry templates and linkers. This engine leads us to isolate six new nanoscale cluster compounds: 1, {Mo(10)(C5)}; 2, {Mo(14)(C4)4(C5)2}; 3, {Mo(60)(C4)10}; 4, {Mo(48)(C4)6}; 5, {Mo(34)(C4)4}; 6, {Mo(18)(C4)9}; in only 200 automated experiments from a parameter space spanning ~5 million possible combinations.

  19. Evaluation and silicon nitride internal combustion engine components. Final report, Phase I

    Energy Technology Data Exchange (ETDEWEB)

    Voldrich, W. [Allied-Signal Aerospace Co., Torrance, CA (United States). Garrett Ceramic Components Div.

    1992-04-01

    The feasibility of silicon nitride (Si{sub 3}N{sub 4}) use in internal combustion engines was studied by testing three different components for wear resistance and lower reciprocating mass. The information obtained from these preliminary spin rig and engine tests indicates several design changes are necessary to survive high-stress engine applications. The three silicon nitride components tested were valve spring retainers, tappet rollers, and fuel pump push rod ends. Garrett Ceramic Components` gas-pressure sinterable Si{sub 3}N{sub 4} (GS-44) was used to fabricate the above components. Components were final machined from densified blanks that had been green formed by isostatic pressing of GS-44 granules. Spin rig testing of the valve spring retainers indicated that these Si{sub 3}N{sub 4} components could survive at high RPM levels (9,500) when teamed with silicon nitride valves and lower spring tension than standard titanium components. Silicon nitride tappet rollers showed no wear on roller O.D. or I.D. surfaces, steel axles and lifters; however, due to the uncrowned design of these particular rollers the cam lobes indicated wear after spin rig testing. Fuel pump push rod ends were successful at reducing wear on the cam lobe and rod end when tested on spin rigs and in real-world race applications.

  20. Engineering Interfacial Silicon Dioxide for Improved Metal-Insulator-Semiconductor Silicon Photoanode Water Splitting Performance.

    Science.gov (United States)

    Satterthwaite, Peter F; Scheuermann, Andrew G; Hurley, Paul K; Chidsey, Christopher E D; McIntyre, Paul C

    2016-05-25

    Silicon photoanodes protected by atomic layer deposited (ALD) TiO2 show promise as components of water splitting devices that may enable the large-scale production of solar fuels and chemicals. Minimizing the resistance of the oxide corrosion protection layer is essential for fabricating efficient devices with good fill factor. Recent literature reports have shown that the interfacial SiO2 layer, interposed between the protective ALD-TiO2 and the Si anode, acts as a tunnel oxide that limits hole conduction from the photoabsorbing substrate to the surface oxygen evolution catalyst. Herein, we report a significant reduction of bilayer resistance, achieved by forming stable, ultrathin (ALD-TiO2 protected anodes were employed: (1) TiO2 deposition directly on an HF-etched Si(100) surface, (2) TiO2 deposition after SiO2 atomic layer deposition on an HF-etched Si(100) surface, and (3) oxygen scavenging, post-TiO2 deposition to decompose the SiO2 layer using a Ti overlayer. Each of these methods provides a progressively superior means of reliably thinning the interfacial SiO2 layer, enabling the fabrication of efficient and stable water oxidation silicon anodes.

  1. Engineering sidewall angles of silica-on-silicon waveguides

    DEFF Research Database (Denmark)

    Haiyan, Ou

    2004-01-01

    Burned photoresist is used as etch mask when producing silica-onsilicon waveguides. The sidewall angle of the optical glass waveguides is engineered by varying photoresist thickness and etch selectivity. The principle for the formation of the angles is introduced and very promising experimental...

  2. The Silicon Tracker of the Beam Test Engineering Model of the GLAST Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    do Couto e Silva, Eduardo

    2000-06-01

    The silicon tracker for the engineering model of the GLAST Large Area Telescope(LAT) has at least two unique features: it employs self triggering readout electronics, dissipating less than 200 mu-W per channel and to date represents the largest surface of silicon microstrip detectors assembled in a tracker (2.7 m{sup 2}). It demonstrates the feasibility of employing this technology for satellite based experiments, in which low power consumption, large effective areas and high reliability are required. This note describes the construction of this silicon tracker, which was installed in a beam test of positrons, hadrons and tagged photons at SLAC in December of 1999 and January of 2000.

  3. Nano-structured polymer scaffolds for tissue engineering and regenerative medicine

    Science.gov (United States)

    Smith, I.O.; Liu, X.H.; Smith, L.A.; Ma, P.X.

    2009-01-01

    scaffolds showed a decrease in incidence of apoptosis when compared to polymer control in bone tissue engineering. Nanoparticles have been integrated into the nano-structured scaffolds to deliver biologically active molecules such as growth and differentiation factors to regulate cell behavior for optimal tissue regeneration. PMID:20049793

  4. A Tremella-Like Nanostructure of Silicon@void@graphene-Like Nanosheets Composite as an Anode for Lithium-Ion Batteries.

    Science.gov (United States)

    Mi, Hongwei; Li, Fang; Xu, Shuxian; Li, Ziang; Chai, Xiaoyan; He, Chuanxin; Li, Yongliang; Liu, Jianhong

    2016-12-01

    Graphene coating is receiving discernable attention to overcome the significant challenges associated with large volume changes and poor conductivity of silicon nanoparticles as anodes for lithium-ion batteries. In this work, a tremella-like nanostructure of silicon@void@graphene-like nanosheets (Si@void@G) composite was successfully synthesized and employed as a high-performance anode material with high capacity, cycling stability, and rate capacity. The Si nanoparticles were first coated with a sacrificial SiO2 layer; then, the nitrogen-doped (N-doped) graphene-like nanosheets were formed on the surface of Si@SiO2 through a one-step carbon-thermal method, and the SiO2 layer was removed subsequently to obtain the Si@void@G composite. The performance improvement is mainly attributed to the good conductivity of N-doped graphene-like nanosheets and the unique design of tremella nanostructure, which provides a void space to allow for the Si nanoparticles expanding upon lithiation. The resulting electrode delivers a capacity of 1497.3 mAh g(-1) at the current density of 0.2 A g(-1) after 100 cycles.

  5. Nanostructured natural-based polyelectrolyte multilayers to agglomerate chitosan particles into scaffolds for tissue engineering.

    Science.gov (United States)

    Miranda, Emanuel Sá; Silva, Tiago H; Reis, Rui L; Mano, João F

    2011-11-01

    The layer-by-layer (LbL) deposition technique is a self-assembly process that allows the coating of material's surface with nanostructured layers of polyelectrolytes, allowing to control several surface properties. This technique presents some advantages when compared with other thin film assembly techniques, like having the possibility to coat surfaces with complex geometries in mild conditions or to incorporate active compounds. Tissue engineering (TE) involves typically the use of porous biodegradable scaffolds for the temporary support of cells. Such structures can be produced by agglomeration of microspheres that needs to be fixed into a three-dimensional (3D) structure. In this work we suggest the use of LbL to promote such mechanical fixation in free-formed microspheres assemblies and simultaneously to control the properties of its surface. For the proof of concept the biological performance of chitosan/alginate multilayers is first investigated in two-dimensional (2D) models in which the attachment and proliferation of L929 and ATDC5 cells are studied in function of the number of layers and the nature of the final layer. Scaffolds prepared by agglomeration of chitosan particles using the same multilayered system were processed and characterized; it was found that they could support the attachment and proliferation of ATDC5 cells. This study suggests that LbL can be used as a versatile methodology to prepare scaffolds by particle agglomeration that could be suitable for TE applications.

  6. Optimization of a nanotechnology based antimicrobial platform for food safety applications using Engineered Water Nanostructures (EWNS)

    Science.gov (United States)

    Pyrgiotakis, Georgios; Vedantam, Pallavi; Cirenza, Caroline; McDevitt, James; Eleftheriadou, Mary; Leonard, Stephen S.; Demokritou, Philip

    2016-01-01

    A chemical free, nanotechnology-based, antimicrobial platform using Engineered Water Nanostructures (EWNS) was recently developed. EWNS have high surface charge, are loaded with reactive oxygen species (ROS), and can interact-with, and inactivate an array of microorganisms, including foodborne pathogens. Here, it was demonstrated that their properties during synthesis can be fine tuned and optimized to further enhance their antimicrobial potential. A lab based EWNS platform was developed to enable fine-tuning of EWNS properties by modifying synthesis parameters. Characterization of EWNS properties (charge, size and ROS content) was performed using state-of-the art analytical methods. Further their microbial inactivation potential was evaluated with food related microorganisms such as Escherichia coli, Salmonella enterica, Listeria innocua, Mycobacterium parafortuitum, and Saccharomyces cerevisiae inoculated onto the surface of organic grape tomatoes. The results presented here indicate that EWNS properties can be fine-tuned during synthesis resulting in a multifold increase of the inactivation efficacy. More specifically, the surface charge quadrupled and the ROS content increased. Microbial removal rates were microorganism dependent and ranged between 1.0 to 3.8 logs after 45 mins of exposure to an EWNS aerosol dose of 40,000 #/cm3. PMID:26875817

  7. Optimization of a nanotechnology based antimicrobial platform for food safety applications using Engineered Water Nanostructures (EWNS)

    Science.gov (United States)

    Pyrgiotakis, Georgios; Vedantam, Pallavi; Cirenza, Caroline; McDevitt, James; Eleftheriadou, Mary; Leonard, Stephen S.; Demokritou, Philip

    2016-02-01

    A chemical free, nanotechnology-based, antimicrobial platform using Engineered Water Nanostructures (EWNS) was recently developed. EWNS have high surface charge, are loaded with reactive oxygen species (ROS), and can interact-with, and inactivate an array of microorganisms, including foodborne pathogens. Here, it was demonstrated that their properties during synthesis can be fine tuned and optimized to further enhance their antimicrobial potential. A lab based EWNS platform was developed to enable fine-tuning of EWNS properties by modifying synthesis parameters. Characterization of EWNS properties (charge, size and ROS content) was performed using state-of-the art analytical methods. Further their microbial inactivation potential was evaluated with food related microorganisms such as Escherichia coli, Salmonella enterica, Listeria innocua, Mycobacterium parafortuitum, and Saccharomyces cerevisiae inoculated onto the surface of organic grape tomatoes. The results presented here indicate that EWNS properties can be fine-tuned during synthesis resulting in a multifold increase of the inactivation efficacy. More specifically, the surface charge quadrupled and the ROS content increased. Microbial removal rates were microorganism dependent and ranged between 1.0 to 3.8 logs after 45 mins of exposure to an EWNS aerosol dose of 40,000 #/cm3.

  8. CW-Laser-Induced Solid-State Reactions in Mixed Micron-Sized Particles of Silicon Monoxide and Titanium Monoxide: Nano-Structured Composite with Visible Light Absorption

    Czech Academy of Sciences Publication Activity Database

    Křenek, T.; Tesař, J.; Kupčík, Jaroslav; Netrvalová, M.; Pola, M.; Jandová, Věra; Pokorná, Dana; Cuřínová, Petra; Bezdička, Petr; Pola, Josef

    2017-01-01

    Roč. 27, č. 6 (2017), s. 1640-1648 ISSN 1574-1443 Institutional support: RVO:61388980 ; RVO:67985858 Keywords : Cw CO2 laser heating * IR laser imaging * Silicon monoxide * Solid state redox reactions * Ti/Si/O composite * Titanium monoxide Subject RIV: CA - Inorganic Chemistry; CI - Industrial Chemistry, Chemical Engineering (UCHP-M) OBOR OECD: Inorganic and nuclear chemistry; Chemical process engineering (UCHP-M) Impact factor: 1.577, year: 2016

  9. Engineered nanostructures: A review of their synthesis, characterization and toxic hazard considerations

    Directory of Open Access Journals (Sweden)

    Fahad S. Al-Mubaddel

    2017-02-01

    Full Text Available Research work on the synthesis, designing and characterization of nanostructures has been extensively documented in the last decades. This in-depth documentation not only enabled researchers to understand the relationship between the nanostructure properties, size, shape, and composition but also have given them immense control over their manufacturing. This enhanced knowledge, cemented the switching of academic nanotechnology research into industrial products. However; despite the recent accomplishment in synthesis, characterization and application of the nanostructure materials, a complete knowledge/information of their interactions with biological systems is still not available. Hence, it is difficult to forecast the injurious biological responses of these novel nanostructures to humans, animals, insects and plants. Due to this hesitancy, safety regulatory authorities and general public have raised their concerns to the manufacturing and use of nanostructure-based products. Consequently, it is vital for the researchers to concentrate more on safe designing, manufacturing and characterization of nanostructures before these could meet human and communal needs. This review is taking an overview of the increasing investments in nanotechnology, designing, synthesis and characterization of nanostructures and their in vitro and in vivo toxicities.

  10. Silicon subsystem mechanical engineering closeout report for the Solenoidal Detector Collaboration

    International Nuclear Information System (INIS)

    Hanlon, J.; Christensen, R.W.; Hayman, G.; Jones, D.C.; Ross, R.; Wilds, W.; Yeamans, S.; Ziock, H.J.

    1995-01-01

    The authors group at Los Alamos National Laboratory was responsible for the mechanical engineering of the silicon tracking system of the Solenoidal Detector Collaboration (SDC) experiment of the Superconducting Super Collider (SSC) project. The responsibility included the overall design of the system from the mechanical point of view, development and integration of the cooling system, which was required to remove the heat generated by the front-end electronics, assembly of the system to extremely tight tolerances, and verification that the construction and operational stability and alignment tolerances would be met. A detailed description of the concepts they developed and the work they performed can be found in a report titled ''Silicon Subsystem Mechanical Engineering Work for the Solenoidal Detector Collaboration'' which they submitted to the SSC Laboratory. In addition to the mechanical engineering work, they also performed activation, background, and shielding studies for the SSC program. Much of the work they performed was potentially useful for other future high energy physics (HEP) projects. This report describes the closeout work that was performed for the Los Alamos SDC project. Four major tasks were identified for completion: (1) integration of the semi-automated assembly station being developed and construction of a precision part to demonstrate solutions to important general assembly problems (the station was designed to build precision silicon tracker subassemblies); (2) build a state-of-the-art TV holography (TVH) system to use for detector assembly stability tests; (3) design, build, and test a water based cooling system for a full silicon shell prototype; and (4) complete and document the activation, background, and shielding studies, which is covered in a separate report

  11. Silicon subsystem mechanical engineering closeout report for the Solenoidal Detector Collaboration

    Science.gov (United States)

    Hanlon, J.; Christensen, R. W.; Hayman, G.; Jones, D. C.; Ross, R.; Wilds, W.; Yeamans, S.; Ziock, H. J.

    The authors' group at Los Alamos National Laboratory was responsible for the mechanical engineering of the silicon tracking system of the Solenoidal Detector Collaboration (SDC) experiment of the Superconducting Super Collider (SSC) project. The responsibility included the overall design of the system from the mechanical point of view, development and integration of the cooling system, which was required to remove the heat generated by the front-end electronics, assembly of the system to extremely tight tolerances, and verification that the construction and operational stability and alignment tolerances would be met. In addition to the mechanical engineering work, they also performed activation, background, and shielding studies for the SSC program. Much of the work they performed was potentially useful for other future high energy physics (HEP) projects. This report describes the closeout work that was performed for the Los Alamos SDC project. Four major tasks were identified for completion: (1) integration of the semi-automated assembly station being developed and construction of a precision part to demonstrate solutions to important general assembly problems (the station was designed to build precision silicon tracker subassemblies); (2) build a state-of-the-art TV holography (TVH) system to use for detector assembly stability tests; (3) design, build, and test a water based cooling system for a full silicon shell prototype; and (4) complete and document the activation, background, and shielding studies, which is covered in a separate report.

  12. Fluorescent Silicon Clusters and Nanoparticles

    OpenAIRE

    von Haeften, Klaus

    2017-01-01

    The fluorescence of silicon clusters is reviewed. Atomic clusters of silicon have been at the focus of research for several decades because of the relevance of size effects for material properties, the importance of silicon in electronics and the potential applications in bio-medicine. To date numerous examples of nanostructured forms of fluorescent silicon have been reported. This article introduces the principles and underlying concepts relevant for fluorescence of nanostructured silicon su...

  13. Interface Optoelectronics Engineering for Mechanically Stacked Tandem Solar Cells Based on Perovskite and Silicon.

    Science.gov (United States)

    Kanda, Hiroyuki; Uzum, Abdullah; Nishino, Hitoshi; Umeyama, Tomokazu; Imahori, Hiroshi; Ishikawa, Yasuaki; Uraoka, Yukiharu; Ito, Seigo

    2016-12-14

    Engineering of photonics for antireflection and electronics for extraction of the hole using 2.5 nm of a thin Au layer have been performed for two- and four-terminal tandem solar cells using CH 3 NH 3 PbI 3 perovskite (top cell) and p-type single crystal silicon (c-Si) (bottom cell) by mechanically stacking. Highly transparent connection multilayers of evaporated-Au and sputtered-ITO films were fabricated at the interface to be a point-contact tunneling junction between the rough perovskite and flat silicon solar cells. The mechanically stacked tandem solar cell with an optimized tunneling junction structure was ⟨perovskite for the top cell/Au (2.5 nm)/ITO (154 nm) stacked-on ITO (108 nm)/c-Si for the bottom cell⟩. It was confirmed the best efficiency of 13.7% and 14.4% as two- and four-terminal devices, respectively.

  14. A review of materials engineering in silicon-based optical fibres

    Science.gov (United States)

    Healy, Noel; Gibson, Ursula; Peacock, Anna C.

    2018-02-01

    Semiconductor optical fibre technologies have grown rapidly in the last decade and there are now a range of production and post-processing techniques that allow for a vast degree of control over the core material's optoelectronic properties. These methodologies and the unique optical fibre geometry provide an exciting platform for materials engineering and fibres can now be produced with single crystal cores, low optical losses, tunable strain, and inscribable phase composition. This review discusses the state-of-the-art regarding the production of silicon optical fibres in amorphous and crystalline form and then looks at the post-processing techniques and the improved material quality and new functionality that they afford.

  15. Bottom-up engineering of the surface roughness of nanostructured cubic zirconia to control cell adhesion

    International Nuclear Information System (INIS)

    Singh, A V; Ferri, M; Tamplenizza, M; Borghi, F; Lenardi, C; Piazzoni, C; Podestà, A; Milani, P; Divitini, G; Ducati, C; Merlini, M

    2012-01-01

    Nanostructured cubic zirconia is a strategic material for biomedical applications since it combines superior structural and optical properties with a nanoscale morphology able to control cell adhesion and proliferation. We produced nanostructured cubic zirconia thin films at room temperature by supersonic cluster beam deposition of nanoparticles produced in the gas phase. Precise control of film roughness at the nanoscale is obtained by operating in a ballistic deposition regime. This allows one to study the influence of nanoroughness on cell adhesion, while keeping the surface chemistry constant. We evaluated cell adhesion on nanostructured zirconia with an osteoblast-like cell line using confocal laser scanning microscopy for detailed morphological and cytoskeleton studies. We demonstrated that the organization of cytoskeleton and focal adhesion formation can be controlled by varying the evolution of surface nanoroughness. (paper)

  16. Enhanced photovoltaic performance of inverted pyramid-based nanostructured black-silicon solar cells passivated by an atomic-layer-deposited Al2O3 layer

    Science.gov (United States)

    Chen, Hong-Yan; Lu, Hong-Liang; Ren, Qing-Hua; Zhang, Yuan; Yang, Xiao-Feng; Ding, Shi-Jin; Zhang, David Wei

    2015-09-01

    Inverted pyramid-based nanostructured black-silicon (BS) solar cells with an Al2O3 passivation layer grown by atomic layer deposition (ALD) have been demonstrated. A multi-scale textured BS surface combining silicon nanowires (SiNWs) and inverted pyramids was obtained for the first time by lithography and metal catalyzed wet etching. The reflectance of the as-prepared BS surface was about 2% lower than that of the more commonly reported upright pyramid-based SiNW BS surface over the whole of the visible light spectrum, which led to a 1.7 mA cm-2 increase in short circuit current density. Moreover, the as-prepared solar cells were further passivated by an ALD-Al2O3 layer. The effect of annealing temperature on the photovoltaic performance of the solar cells was investigated. It was found that the values of all solar cell parameters including short circuit current, open circuit voltage, and fill factor exhibit a further increase under an optimized annealing temperature. Minority carrier lifetime measurements indicate that the enhanced cell performance is due to the improved passivation quality of the Al2O3 layer after thermal annealing treatments. By combining these two refinements, the optimized SiNW BS solar cells achieved a maximum conversion efficiency enhancement of 7.6% compared to the cells with an upright pyramid-based SiNWs surface and conventional SiNx passivation.

  17. Modelling of the hydrogen effects on the morphogenesis of hydrogenated silicon nano-structures in a plasma reactor; Modelisation des effets de l'hydrogene sur la morphogenese des nanostructures de silicium hydrogene dans un reacteur plasma

    Energy Technology Data Exchange (ETDEWEB)

    Brulin, Q

    2006-01-15

    This work pursues the goal of understanding mechanisms related to the morphogenesis of hydrogenated silicon nano-structures in a plasma reactor through modeling techniques. Current technologies are first reviewed with an aim to understand the purpose behind their development. Then follows a summary of the possible studies which are useful in this particular context. The various techniques which make it possible to simulate the trajectories of atoms by molecular dynamics are discussed. The quantum methods of calculation of the interaction potential between chemical species are then developed, reaching the conclusion that only semi-empirical quantum methods are sufficiently fast to be able to implement an algorithm of quantum molecular dynamics on a reasonable timescale. From the tools introduced, a reflection on the nature of molecular metastable energetic states is presented for the theoretical case of the self-organized growth of a linear chain of atoms. This model - which consists of propagating the growth of a chain by the successive addition of the atom which least increases the electronic energy of the chain - shows that the Fermi level is a parameter essential to self organization during growth. This model also shows that the structure formed is not necessarily a total minimum energy structure. From all these numerical tools, the molecular growth of clusters can be simulated by using parameters from magnetohydrodynamic calculation results of plasma reactor modeling (concentrations of the species, interval between chemical reactions, energy of impact of the reagents...). The formation of silicon-hydrogen clusters is thus simulated by the successive capture of silane molecules. The structures formed in simulation at the operating temperatures of the plasma reactor predict the formation of spherical clusters constituting an amorphous silicon core covered by hydrogen. These structures are thus not in a state of minimum energy, contrary to certain experimental

  18. Silicon-Based Anodes for Lithium-Ion Batteries: From Fundamentals to Practical Applications.

    Science.gov (United States)

    Feng, Kun; Li, Matthew; Liu, Wenwen; Kashkooli, Ali Ghorbani; Xiao, Xingcheng; Cai, Mei; Chen, Zhongwei

    2018-02-01

    Silicon has been intensively studied as an anode material for lithium-ion batteries (LIB) because of its exceptionally high specific capacity. However, silicon-based anode materials usually suffer from large volume change during the charge and discharge process, leading to subsequent pulverization of silicon, loss of electric contact, and continuous side reactions. These transformations cause poor cycle life and hinder the wide commercialization of silicon for LIBs. The lithiation and delithiation behaviors, and the interphase reaction mechanisms, are progressively studied and understood. Various nanostructured silicon anodes are reported to exhibit both superior specific capacity and cycle life compared to commercial carbon-based anodes. However, some practical issues with nanostructured silicon cannot be ignored, and must be addressed if it is to be widely used in commercial LIBs. This Review outlines major impactful work on silicon-based anodes, and the most recent research directions in this field, specifically, the engineering of silicon architectures, the construction of silicon-based composites, and other performance-enhancement studies including electrolytes and binders. The burgeoning research efforts in the development of practical silicon electrodes, and full-cell silicon-based LIBs are specially stressed, which are key to the successful commercialization of silicon anodes, and large-scale deployment of next-generation high energy density LIBs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Plasmonic Nanostructures for Biosensor Applications

    Science.gov (United States)

    Gadde, Akshitha

    Improving the sensitivity of existing biosensors is an active research topic that cuts across several disciplines, including engineering and biology. Optical biosensors are the one of the most diverse class of biosensors which can be broadly categorized into two types based on the detection scheme: label-based and label-free detection. In label-based detection, the target bio-molecules are labeled with dyes or tags that fluoresce upon excitation, indicating the presence of target molecules. Label-based detection is highly-sensitive, capable of single molecule detection depending on the detector type used. One method of improving the sensitivity of label-based fluorescence detection is by enhancement of the emission of the labels by coupling them with metal nanostructures. This approach is referred as plasmon-enhanced fluorescence (PEF). PEF is achieved by increasing the electric field around the nano metal structures through plasmonics. This increased electric field improves the enhancement from the fluorophores which in turn improves the photon emission from the fluorophores which, in turn, improves the limit of detection. Biosensors taking advantage of the plasmonic properties of metal films and nanostructures have emerged an alternative, low-cost, high sensitivity method for detecting labeled DNA. Localized surface plasmon resonance (LSPR) sensors employing noble metal nanostructures have recently attracted considerable attention as a new class of plasmonic nanosensors. In this work, the design, fabrication and characterization of plasmonic nanostructures is carried out. Finite difference time domain (FDTD) simulations were performed using software from Lumerical Inc. to design a novel LSPR structure that exhibit resonance overlapping with the absorption and emission wavelengths of quantum dots (QD). Simulations of a composite Au/SiO2 nanopillars on silicon substrate were performed using FDTD software to show peak plasmonic enhancement at QD emission wavelength

  20. Improved bandwidth and quantum efficiency in silicon photodiodes using photon-manipulating micro/nanostructures operating in the range of 700-1060 nm

    Science.gov (United States)

    Cansizoglu, Hilal; Gao, Yang; Ghandiparsi, Soroush; Kaya, Ahmet; Perez, Cesar Bartolo; Mayet, Ahmed; Ponizovskaya Devine, Ekaterina; Cansizoglu, Mehmet F.; Yamada, Toshishige; Elrefaie, Aly F.; Wang, Shih-Yuan; Islam, M. Saif

    2017-08-01

    Nanostructures allow broad spectrum and near-unity optical absorption and contributed to high performance low-cost Si photovoltaic devices. However, the efficiency is only a few percent higher than a conventional Si solar cell with thicker absorption layers. For high speed surface illuminated photodiodes, the thickness of the absorption layer is critical for short transit time and RC time. Recently a CMOS-compatible micro/nanohole silicon (Si) photodiode (PD) with more than 20 Gb/s data rate and with 52 % quantum efficiency (QE) at 850 nm was demonstrated. The achieved QE is over 400% higher than a similar Si PD with the same thickness but without absorption enhancement microstructure holes. The micro/nanoholes increases the QE by photon trapping, slow wave effects and generate a collective assemble of modes that radiate laterally, resulting in absorption enhancement and therefore increase in QE. Such Si PDs can be further designed to enhance the bandwidth (BW) of the PDs by reducing the device capacitance with etched holes in the pin junction. Here we present the BW and QE of Si PDs achievable with micro/nanoholes based on a combination of empirical evidence and device modeling. Higher than 50 Gb/s data rate with greater than 40% QE at 850 nm is conceivable in transceivers designed with such Si PDs that are integrated with photon trapping micro and nanostructures. By monolithic integration with CMOS/BiCMOS integrated circuits such as transimpedance amplifiers, equalizers, limiting amplifiers and other application specific integrated circuits (ASIC), the data rate can be increased to more than 50 Gb/s.

  1. Injection moulding antireflective nanostructures

    DEFF Research Database (Denmark)

    Christiansen, Alexander Bruun; Clausen, Jeppe Sandvik; Mortensen, N. Asger

    We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used in an inject......We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used...... in an injection moulding process, to fabricate the antireflective surfaces. The cycle-time was 35 s. The injection moulded structures had a height of 125 nm, and the visible spectrum reflectance of injection moulded black polypropylene surfaces was reduced from 4.5±0.5% to 2.5±0.5%. The gradient of the refractive...

  2. Feasibility study on silicon doping using high temperature test engineering reactor

    International Nuclear Information System (INIS)

    Seki, Masaya; Takaki, Naoyuki; Goto, Minoru; Shimakawa, Satoshi

    2011-01-01

    The feasibility study on silicon doping using the High Temperature engineering Test Reactor (HTTR) is performed by numerical simulations. The HTTR is a High Temperature Gas-cooled Reactor (HTGR) situated at JAEA Oarai research and development center. It has a 30MW thermal power and the outlet coolant temperature is 950degC. The objective of this study is to evaluate the following issues, 1. The impact of loading Si-ingots into the core on the criticality, 2. The uniformity of the neutron capture reaction rate in Si-ingots, and 3. The production rate of silicon semiconductor. In this study, six Si-ingots are loaded into the irradiation area which is located in the peripheral region of the core. They are irradiated with rotation movement around the axial direction to obtain uniform neutron capture reaction rate in the radial direction. Additionally, the neutron filter, which is made of graphite containing boron, is used to obtain uniform neutron capture reaction rate in the axial direction. The evaluations were conducted by performing the HTTR whole core calculations with the Monte Carlo code MVP-2.0. In the calculations, several tally regions were defined on the Si-ingots to investigate the uniformity of the neutron capture reaction rate. As a result, loading the Si-ingots into the core causes negative reactivity by about 0.7%dk/k. Uniform neutron capture reaction rate of Si-ingot is obtained 98% in the radial and the axial direction. In case of the target of semiconductor resistivity is set to 50 Ωcm, the required irradiation time becomes 10 hours. The HTTR is able to produce silicon semiconductor of 540kg in one-time irradiation. This study was conducted as a joint research with JAEA, Nuclear Fuel Industries, LTD, Toyota Tsusho Corporation and Tokai University. (author)

  3. Nanostructure Size Determination in N+-Type Porous Silicon by X-Ray diffractometry and Raman Spectroscopy

    CERN Document Server

    Ramirez-Porras, A

    1997-01-01

    A series of porous silicon surfaces were obtained after different exposition times of electrochemical etching on cristalline n+- type silicon in presence of hydrofluoric acid. These kind of surfaces show photoluminescence when illuminated by UV light. One possible explanation for this is that the treated surface is made up of small crystallites the nanometer scale that split away the semiconductor band edges up to optical photon energies for the band- to -band recombination processes. In this study, a nanometer size determination of such proposed structures was performed by the use of X-Ray Diffractometry and Raman Spectroscopy. The result suggest the consistency between the so called Quantum Confined Model and the experimental results. (Author)

  4. Engineering metal precipitate size distributions to enhance gettering in multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Jasmin; Fenning, David P.; Buonassisi, Tonio [Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge MA, 02139 (United States); Lelievre, Jean-Francois [Universidad Politecnica de Madrid, Avd. Complutense s/n, 28040 Madrid (Spain); Del Canizo, Carlos [Centro de Tecnologia del Silicio Solar CENTESIL, Getafe (Spain)

    2012-10-15

    The extraction of metal impurities during phosphorus diffusion gettering (PDG) is one of the crucial process steps when fabricating high-efficiency solar cells using low-cost, lower-purity silicon wafers. In this work, we show that for a given metal concentration, the size and density of metal silicide precipitates strongly influences the gettering efficacy. Different precipitate size distributions can be already found in silicon wafers grown by different techniques. In our experiment, however, the as-grown distribution of precipitated metals in multicrystalline Si sister wafers is engineered through different annealing treatments in order to control for the concentration and distribution of other defects. A high density of small precipitates is formed during a homogenization step, and a lower density of larger precipitates is formed during extended annealing at 740 C. After PDG, homogenized samples show a decreased interstitial iron concentration compared to as-grown and ripened samples, in agreement with simulations. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. DNA Nanostructure-based Interfacial engineering for PCR-free ultrasensitive electrochemical analysis of microRNA

    Science.gov (United States)

    Wen, Yanli; Pei, Hao; Shen, Ye; Xi, Junjie; Lin, Meihua; Lu, Na; Shen, Xizhong; Li, Jiong; Fan, Chunhai

    2012-11-01

    MicroRNAs (miRNAs) have been identified as promising cancer biomarkers due to their stable presence in serum. As an alternative to PCR-based homogenous assays, surface-based electrochemical biosensors offer great opportunities for low-cost, point-of-care tests (POCTs) of disease-associated miRNAs. Nevertheless, the sensitivity of miRNA sensors is often limited by mass transport and crowding effects at the water-electrode interface. To address such challenges, we herein report a DNA nanostructure-based interfacial engineering approach to enhance binding recognition at the gold electrode surface and drastically improve the detection sensitivity. By employing this novel strategy, we can directly detect as few as attomolar (electrochemical miRNA sensor (EMRS) is highly reproducible and essentially free of prior target labeling and PCR amplification, we also demonstrate its application by analyzing miRNA expression levels in clinical samples from esophageal squamous cell carcinoma (ESCC) patients.

  6. Ex-Vivo Tissues Engineering Modeling for Reconstructive Surgery Using Human Adult Adipose Stem Cells and Polymeric Nanostructured Matrix.

    Science.gov (United States)

    Morena, Francesco; Argentati, Chiara; Calzoni, Eleonora; Cordellini, Marino; Emiliani, Carla; D'Angelo, Francesco; Martino, Sabata

    2016-03-31

    The major challenge for stem cell translation regenerative medicine is the regeneration of damaged tissues by creating biological substitutes capable of recapitulating the missing function in the recipient host. Therefore, the current paradigm of tissue engineering strategies is the combination of a selected stem cell type, based on their capability to differentiate toward committed cell lineages, and a biomaterial, that, due to own characteristics (e.g., chemical, electric, mechanical property, nano-topography, and nanostructured molecular components), could serve as active scaffold to generate a bio-hybrid tissue/organ. Thus, effort has been made on the generation of in vitro tissue engineering modeling. Here, we present an in vitro model where human adipose stem cells isolated from lipoaspirate adipose tissue and breast adipose tissue, cultured on polymeric INTEGRA ® Meshed Bilayer Wound Matrix (selected based on conventional clinical applications) are evaluated for their potential application for reconstructive surgery toward bone and adipose tissue. We demonstrated that human adipose stem cells isolated from lipoaspirate and breast tissue have similar stemness properties and are suitable for tissue engineering applications. Finally, the overall results highlighted lipoaspirate adipose tissue as a good source for the generation of adult adipose stem cells.

  7. Ferromagnetic (Ga,Mn)As layers and nanostructures: control of magnetic anisotropy by strain engineering

    Energy Technology Data Exchange (ETDEWEB)

    Wenisch, Jan

    2008-07-01

    This work studies the fundamental connection between lattice strain and magnetic anisotropy in the ferromagnetic semiconductor (Ga,Mn)As. The first chapters provide a general introduction into the material system and a detailed description of the growth process by molecular beam epitaxy. A finite element simulation formalism is developed to model the strain distribution in (Ga,Mn)As nanostructures is introduced and its predictions verified by high-resolution X-ray diffraction methods. The influence of lattice strain on the magnetic anisotropy is explained by an magnetostatic model. A possible device application is described in the closing chapter. (orig.)

  8. In situ TEM investigation of congruent phase transition and structural evolution of nanostructured silicon/carbon anode for lithium ion batteries.

    Science.gov (United States)

    Wang, Chong-Min; Li, Xiaolin; Wang, Zhiguo; Xu, Wu; Liu, Jun; Gao, Fei; Kovarik, Libor; Zhang, Ji-Guang; Howe, Jane; Burton, David J; Liu, Zhongyi; Xiao, Xingcheng; Thevuthasan, Suntharampillai; Baer, Donald R

    2012-03-14

    It is well-known that upon lithiation, both crystalline and amorphous Si transform to an armorphous Li(x)Si phase, which subsequently crystallizes to a (Li, Si) crystalline compound, either Li(15)Si(4) or Li(22)Si(5). Presently, the detailed atomistic mechanism of this phase transformation and the degradation process in nanostructured Si are not fully understood. Here, we report the phase transformation characteristic and microstructural evolution of a specially designed amorphous silicon (a-Si) coated carbon nanofiber (CNF) composite during the charge/discharge process using in situ transmission electron microscopy and density function theory molecular dynamic calculation. We found the crystallization of Li(15)Si(4) from amorphous Li(x)Si is a spontaneous, congruent phase transition process without phase separation or large-scale atomic motion, which is drastically different from what is expected from a classic nucleation and growth process. The a-Si layer is strongly bonded to the CNF and no spallation or cracking is observed during the early stages of cyclic charge/discharge. Reversible volume expansion/contraction upon charge/discharge is fully accommodated along the radial direction. However, with progressive cycling, damage in the form of surface roughness was gradually accumulated on the coating layer, which is believed to be the mechanism for the eventual capacity fade of the composite anode during long-term charge/discharge cycling. © 2012 American Chemical Society

  9. Inclusion of gold nanoparticles in meso-porous silicon for the SERS analysis of cell adhesion on nano-structured surfaces

    KAUST Repository

    Coluccio, M.L.

    2016-03-25

    The study and the comprehension of the mechanism of cell adhesion and cell interaction with a substrate is a key point when biology and medicine meet engineering. This is the case of several biomedical applications, from regenerative medicine and tissue engineering to lab on chip and many others, in which the realization of the appropriate artificial surface allows the control of cell adhesion and proliferation. In this context, we aimed to design and develop a fabrication method of mesoporous (MeP) silicon substrates, doped with gold nanoparticles, in which we combine the capability of porous surfaces to support cell adhesion with the SERS capabilities of gold nanoparticles, to understand the chemical mechanisms of cell/surface interaction. MeP Si surfaces were realized by anodization of a Si wafer, creating the device for cell adhesion and growth. Gold nanoparticles were deposited on porous silicon by an electroless technique. We thus obtained devices with superior SERS capabilities, whereby cell activity may be controlled using Raman spectroscopy. MCF-7 breast cancer cells were cultured on the described substrates and SERS maps revealing the different expression and distribution of adhesion molecules were obtained by Raman spectroscopic analyses.

  10. Semiconductor nanostructures on silicon. Carrier dynamics, optical amplification and lasing; Halbleiternanostrukturen auf Silizium. Ladungstraegerdynamik, optischer Verstaerker und Laser

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Christoph

    2008-12-11

    Two material systems that can be grown epitaxially on a silicon substrate are experimentally investigated with respect to their optical properties. Quantum wells (qw) of Germanium were experimentally investigated by spectrally resolved white-light pump-probe-absorption spectroscopy at room temperature. A second material class is Ga(NAsP), which was grown as quantum wells on a silicon substrate matching the lattice constant of the substrate. The basic optical properties were determined using the variable stripe-length method. In order to relate the results to those of established materials, a selection of comparable III/V semiconductors were measured in the same setups. The pump-probe measurements on (GaIn)As quantum wells exhibited a much more rapid scattering. In these material systems, quite similar optical gain values of 10{sup -3}/QW were found with decay times of several 100 ps. For (GaIn)(NAs), slightly higher values were determined. Using the variable stripe-length method, GaSb quantum wells with dot-like morphology were investigated. (orig.)

  11. Role of metal/silicon semiconductor contact engineering for enhanced output current in micro-sized microbial fuel cells

    KAUST Repository

    Mink, Justine E.

    2013-11-25

    We show that contact engineering plays an important role to extract the maximum performance from energy harvesters like microbial fuel cells (MFCs). We experimented with Schottky and Ohmic methods of fabricating contact areas on silicon in an MFC contact material study. We utilized the industry standard contact material, aluminum, as well as a metal, whose silicide has recently been recognized for its improved performance in smallest scale integration requirements, cobalt. Our study shows that improvements in contact engineering are not only important for device engineering but also for microsystems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. An engineered CARS substrate with giant field enhancement in crisscross dimer nanostructure.

    Science.gov (United States)

    Zhang, Jia; Chen, Shu; Wang, Junqiao; Mu, Kaijun; Fan, Chunzhen; Liang, Erjun; Ding, Pei

    2018-01-15

    We theoretically investigate the optical properties of a nanostructure consisting of the two identical and symmetrically arranged crisscrosses. A plasmonic Fano resonance is induced by a strong interplay between bright mode and dark modes, where the bright mode is due to electric dipole resonance while dark modes originate from the magnetic dipole induced by LC resonances. In this article, we find that the electric field "hotspots" corresponding to three different wavelengths can be positioned at the same spatial position, and its spectral tunability is achieved by changing geometric parameters. The crisscrosses system can be designed as a plasmonic substrate for enhancing Coherent Anti-Stokes Raman Scattering (CARS) signal. This discovery provides a new method to achieve single molecule detection. At the same time, it also has many important applications for multi-photon imaging and other nonlinear optical processes, such as four-wave mixing and stimulated Raman scattering.

  13. Performance of ultrathin silicon solar microcells with nanostructures of relief formed by soft imprint lithography for broad band absorption enhancement.

    Science.gov (United States)

    Shir, Dan; Yoon, Jongseung; Chanda, Debashis; Ryu, Jae-Ha; Rogers, John A

    2010-08-11

    Recently developed classes of monocrystalline silicon solar microcells can be assembled into modules with characteristics (i.e., mechanically flexible forms, compact concentrator designs, and high-voltage outputs) that would be impossible to achieve using conventional, wafer-based approaches. This paper presents experimental and computational studies of the optics of light absorption in ultrathin microcells that include nanoscale features of relief on their surfaces, formed by soft imprint lithography. Measurements on working devices with designs optimized for broad band trapping of incident light indicate good efficiencies in energy production even at thicknesses of just a few micrometers. These outcomes are relevant not only to the microcell technology described here but also to other photovoltaic systems that benefit from thin construction and efficient materials utilization.

  14. Mimicking both petal and lotus effects on a single silicon substrate by tuning the wettability of nanostructured surfaces.

    Science.gov (United States)

    Dawood, M K; Zheng, H; Liew, T H; Leong, K C; Foo, Y L; Rajagopalan, R; Khan, S A; Choi, W K

    2011-04-05

    We describe a new method of fabricating large-area, highly scalable, "hybrid" superhydrophobic surfaces on silicon (Si) substrates with tunable, spatially selective adhesion behavior by controlling the morphologies of Si nanowire arrays. Gold (Au) nanoparticles were deposited on Si by glancing-angle deposition, followed by metal-assisted chemical etching of Si to form Si nanowire arrays. These surfaces were chemically modified and rendered hydrophobic by fluorosilane deposition. Au nanoparticles with different size distributions resulted in the synthesis of Si nanowires with very different morphologies (i.e., clumped and straight nanowire surfaces). The difference in nanowire morphology is attributed to capillary force-induced nanocohesion, which is due to the difference in nanowire porosity. The clumped nanowire surface demonstrated the lotus effect, and the straighter nanowires demonstrated the ability to pin water droplets while maintaining large contact angles (i.e., the petal effect). The high contact angles in both cases are explained by invoking the Cassie-Baxter wetting state. The high adhesion behavior of the straight nanowire surface may be explained by a combination of attractive van der Waals forces and capillary adhesion. We demonstrate the spatial patterning of both low- and high-adhesion superhydrophobicity on the same substrate by the simultaneous synthesis of clumped and straight silicon nanowires. The demonstration of hybrid superhydrophobic surfaces with spatially selective, tunable adhesion behavior on single substrates paves the way for future applications in microfluidic channels, substrates for biologically and chemically based analysis and detection where it is necessary to analyze a particular droplet in a defined location on a surface, and as a platform to study in situ chemical mixing and interfacial reactions of liquid pearls.

  15. Novel scalable silicone elastomer and poly(2-hydroxyethyl methacrylate) (PHEMA) composite materials for tissue engineering and drug delivery applications

    DEFF Research Database (Denmark)

    Mohanty, Soumyaranjan; Hemmingsen, Mette; Wojcik, Magdalena

    2013-01-01

    In recent years hydrogels have received increasing attention as potential materials for applications in regenerative medicine. They can be used for scaffold materials providing structural integrity to tissue constructs, for controlled delivery of drugs and proteins to cell and tissues......, and for support materials in tissue growth. However, the real challenge is to obtain sufficiently good mechanical properties of the hydrogel. The present study shows the combination of two normally non-compatible materials, silicone elastomer and poly(2-hydroxyethyl methacrylate) (PHEMA), into a novel composite...... material with increased hydrophilicity in regard to virgin silicone elastomer, making it suitable as a scaffold for tissue engineering and with the concomitant possibility for delivering drug from the scaffold to the tissue. Interpenetrating polymer networks (IPNs) of silicone elastomer and PHEMA...

  16. Micromachining with Nanostructured Cutting Tools

    CERN Document Server

    Jackson, Mark J

    2013-01-01

    The purpose of the brief is to explain how nanostructured tools can be used to machine materials at the microscale.  The aims of the brief are to explain to readers how to apply nanostructured tools to micromachining applications. This book describes the application of nanostructured tools to machining engineering materials and includes methods for calculating basic features of micromachining. It explains the nature of contact between tools and work pieces to build a solid understanding of how nanostructured tools are made.

  17. Defects in semiconductor nanostructures

    Indian Academy of Sciences (India)

    Impurities play a pivotal role in semiconductors. One part in a million of phosphorous in silicon alters the conductivity of the latter by several orders of magnitude. Indeed, the information age is possible only because of the unique role of shallow impurities in semiconductors. Although work in semiconductor nanostructures ...

  18. Self-organized nickel nanoparticles on nanostructured silicon substrate intermediated by a titanium oxynitride (TiNxOy interface

    Directory of Open Access Journals (Sweden)

    M. Morales

    2018-01-01

    Full Text Available In this work we report an experimental approach by combining in situ sequential top-down and bottom-up processes to induce the organization of nanosized nickel particles. The top-down process consists in xenon ion bombardment of a crystalline silicon substrate to generate a pattern, followed by depositing a ∼15 nm titanium oxynitride thin film to act as a metallic diffusion barrier. Then, metallic nanoparticles are deposited by argon ion sputtering a pure nickel target, and the sample is annealed to promote the organization of the nickel nanoparticles (a bottom-up process. According to the experimental results, the surface pattern and the substrate biaxial surface strain are the driving forces behind the alignment and organization of the nickel nanoparticles. Moreover, the ratio between the F of metallic atoms arriving at the substrate relative to its surface diffusion mobility determines the nucleation regime of the nickel nanoparticles. These features are presented and discussed considering the existing technical literature on the subject.

  19. Improving Crystalline Silicon Solar Cell Efficiency Using Graded-Refractive-Index SiON/ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    Yung-Chun Tu

    2015-01-01

    Full Text Available The fabrication of silicon oxynitride (SiON/ZnO nanotube (NT arrays and their application in improving the energy conversion efficiency (η of crystalline Si-based solar cells (SCs are reported. The SiON/ZnO NT arrays have a graded-refractive-index that varies from 3.5 (Si to 1.9~2.0 (Si3N4 and ZnO to 1.72~1.75 (SiON to 1 (air. Experimental results show that the use of 0.4 μm long ZnO NT arrays coated with a 150 nm thick SiON film increases Δη/η by 39.2% under AM 1.5 G (100 mW/cm2 illumination as compared to that of regular SCs with a Si3N4/micropyramid surface. This enhancement can be attributed to SiON/ZnO NT arrays effectively releasing surface reflection and minimizing Fresnel loss.

  20. Self-organized nickel nanoparticles on nanostructured silicon substrate intermediated by a titanium oxynitride (TiNxOy) interface

    Science.gov (United States)

    Morales, M.; Droppa, R., Jr.; de Mello, S. R. S.; Figueroa, C. A.; Zanatta, A. R.; Alvarez, F.

    2018-01-01

    In this work we report an experimental approach by combining in situ sequential top-down and bottom-up processes to induce the organization of nanosized nickel particles. The top-down process consists in xenon ion bombardment of a crystalline silicon substrate to generate a pattern, followed by depositing a ˜15 nm titanium oxynitride thin film to act as a metallic diffusion barrier. Then, metallic nanoparticles are deposited by argon ion sputtering a pure nickel target, and the sample is annealed to promote the organization of the nickel nanoparticles (a bottom-up process). According to the experimental results, the surface pattern and the substrate biaxial surface strain are the driving forces behind the alignment and organization of the nickel nanoparticles. Moreover, the ratio between the F of metallic atoms arriving at the substrate relative to its surface diffusion mobility determines the nucleation regime of the nickel nanoparticles. These features are presented and discussed considering the existing technical literature on the subject.

  1. Atomic-scale engineering of magnetic anisotropy of nanostructures through interfaces and interlines.

    Science.gov (United States)

    Ouazi, S; Vlaic, S; Rusponi, S; Moulas, G; Buluschek, P; Halleux, K; Bornemann, S; Mankovsky, S; Minár, J; Staunton, J B; Ebert, H; Brune, H

    2012-01-01

    The central goals of nanoscale magnetic materials science are the self-assembly of the smallest structure exhibiting ferromagnetic hysteresis at room temperature, and the assembly of these structures into the highest density patterns. The focus has been on chemically ordered alloys combining magnetic 3d elements with polarizable 5d elements having high spin-orbit coupling and thus yielding the desired large magneto-crystalline anisotropy. The chemical synthesis of nanoparticles of these alloys yields disordered phases requiring annealing to transform them to the high-anisotropy L1(0) structure. Despite considerable efforts, so far only part of the nanoparticles can be transformed without coalescence. Here we present an alternative approach to homogeneous alloys, namely the creation of nanostructures with atomically sharp bimetallic interfaces and interlines. They exhibit unexpectedly high magnetization reversal energy with values and directions of the easy magnetization axes strongly depending on chemistry and texture. We find significant deviations from the expected behaviour for commonly used element combinations. Ab-initio calculations reproduce these results and unravel their origin.

  2. CF4 plasma treatment on nanostructure band engineered Gd2O3-nanocrystal nonvolatile memory

    Science.gov (United States)

    Wang, Jer-Chyi; Lin, Chih-Ting

    2011-03-01

    The effects of CF4 plasma treatment on Gd2O3 nanocrystal (NC) memory were investigated. For material analysis, secondary ion mass spectrometry and x-ray photoelectron spectroscopy analyses were performed to characterize the fluorine depth profile of the Gd2O3-NC film. In addition, an UV-visible spectrophotometer was used to obtain the Gd2O3 bandgap and analyzed to suggest the modified structure of the energy band. Moreover, the electrical properties, including the memory window, program/erase speed, charge retention, and endurance characteristics were significantly improved depending on the CF4 plasma treatment conditions. This can be explained by the physical model based on the built-in electric field in the Gd2O3 nanostructure. However, it was observed that too much CF4 plasma caused large surface roughness induced by the plasma damage, leading to characteristics degradation. It was concluded that with suitable CF4 plasma treatment, this Gd2O3-NC memory can be applied to future nonvolatile memory applications.

  3. Plasmonic amplifiers: engineering giant light enhancements by tuning resonances in multiscale plasmonic nanostructures.

    Science.gov (United States)

    Chen, Aiqing; Miller, Ryan L; DePrince, A Eugene; Joshi-Imre, Alexandra; Shevchenko, Elena; Ocola, Leonidas E; Gray, Stephen K; Welp, Ulrich; Vlasko-Vlasov, Vitalii K

    2013-06-10

    The unique ability of plasmonic nanostructures to guide, enhance, and manipulate subwavelength light offers multiple novel applications in chemical and biological sensing, imaging, and photonic microcircuitry. Here the reproducible, giant light amplification in multiscale plasmonic structures is demonstrated. These structures combine strongly coupled components of different dimensions and topologies that resonate at the same optical frequency. A light amplifier is constructed using a silver mirror carrying light-enhancing surface plasmons, dielectric gratings forming distributed Bragg cavities on top of the mirror, and gold nanoparticle arrays self-assembled into the grating grooves. By tuning the resonances of the individual components to the same frequency, multiple enhancement of the light intensity in the nanometer gaps between the particles is achieved. Using a monolayer of benzenethiol molecules on this structure, an average SERS enhancement factor ∼10⁸ is obtained, and the maximum enhancement in the interparticle hot-spots is ∼3 × 10¹⁰, in good agreement with FDTD calculations. The high enhancement factor, large density of well-ordered hot-spots, and good fidelity of the SERS signal make this design a promising platform for quantitative SERS sensing, optical detection, efficient solid state lighting, advanced photovoltaics, and other emerging photonic applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Engineering in-plane silicon nanowire springs for highly stretchable electronics

    Science.gov (United States)

    Xue, Zhaoguo; Dong, Taige; Zhu, Zhimin; Zhao, Yaolong; Sun, Ying; Yu, Linwei

    2018-01-01

    Crystalline silicon (c-Si) is unambiguously the most important semiconductor that underpins the development of modern microelectronics and optoelectronics, though the rigid and brittle nature of bulk c-Si makes it difficult to implement directly for stretchable applications. Fortunately, the one-dimensional (1D) geometry, or the line-shape, of Si nanowire (SiNW) can be engineered into elastic springs, which indicates an exciting opportunity to fabricate highly stretchable 1D c-Si channels. The implementation of such line-shape-engineering strategy demands both a tiny diameter of the SiNWs, in order to accommodate the strains under large stretching, and a precise growth location, orientation and path control to facilitate device integration. In this review, we will first introduce the recent progresses of an in-plane self-assembly growth of SiNW springs, via a new in-plane solid-liquid-solid (IPSLS) mechanism, where mono-like but elastic SiNW springs are produced by surface-running metal droplets that absorb amorphous Si thin film as precursor. Then, the critical growth control and engineering parameters, the mechanical properties of the SiNW springs and the prospects of developing c-Si based stretchable electronics, will be addressed. This efficient line-shape-engineering strategy of SiNW springs, accomplished via a low temperature batch-manufacturing, holds a strong promise to extend the legend of modern Si technology into the emerging stretchable electronic applications, where the high carrier mobility, excellent stability and established doping and passivation controls of c-Si can be well inherited. Project supported by the National Basic Research 973 Program (No. 2014CB921101), the National Natural Science Foundation of China (No. 61674075), the National Key Research and Development Program of China (No. 2017YFA0205003), the Jiangsu Excellent Young Scholar Program (No. BK20160020), the Scientific and Technological Support Program in Jiangsu Province (No. BE

  5. Silicon Carbide Defect Qubits/Quantum Memory with Field-Tuning: OSD Quantum Science and Engineering Program (QSEP)

    Science.gov (United States)

    2017-08-01

    TECHNICAL REPORT 3073 August 2017 Silicon Carbide Defect Qubits/Quantum Memory with Field-tuning: OSD Quantum Science and Engineering Program...Pacific personnel and working towards supporting demonstrations of quantum entanglement based on these qubits and quantum memories developed out of the...EFFECT OF FIELD-EFFECT TUNINING ....11 5. QUBIT/QUANTUM MEMORY DEVICE DESIGN AND FABRICATION ..............................12 5.1 DEVICE DESIGN

  6. Synthesis, characterization and luminescence properties of zinc oxide nanostructures

    Science.gov (United States)

    Khan, Aurangzeb

    Zinc oxide (ZnO) represents an important semiconductor material due to its wideband gap (3.37 eV at room temperature), large exciton binding energy (60 meV), high optical gain, and luminescence as well as piezoelectric properties [1]. From the 1960s, ZnO thin films have been extensively studied because of their applications as sensors, transducers and catalysts [2]. Since a few decades, one-dimensional nanostructures have become the focus point in nanoscience and nanotechnology. Nanostructures are considered to have unique physical, chemical, catalytic and optical properties that are profoundly different from their bulk counterparts. Since the discovery of carbon nanotubes (CNTs) in 1991, a string of research activities led to the growth and characterization of nanostructures of various materials including semiconductors such as Si, Ge and also compound semiconductors such as InP, GaAs, GaN and ZnO. ZnO is a versatile material and has shown potential for the synthesis of various types of nanostructures such as nanocombs, nanorings, nanohelices/nanosprings, nanobelts, nanowires and nanocages under specific growth conditions and probably has the richest family of nanostructures among all materials, both in structure and properties. This dissertation presents the synthesis, characterization and luminescence properties of ZnO nanostructures with the development of a PVD system. The nanostructures of ZnO are synthesized on various kinds of substrates such as Silicon, Sapphire and Alumina. We have synthesized a large family of nanostructures such as nanowires, nanorods, nanobelts, aligned nanorods, nanosheets, nanospheres, nanocombs, microspheres, hexagons etc. The nanostructures are then characterized by SEM, EDX, TEM, HRTEM, XRD, Raman Spectroscopy, PL and CL. From the characterization of the materials, we observed that these nanostructures are of good crystalline quality. PL and CL spectra reveal that all the nanostructures emit a ˜380 nm (UV) usually called the near

  7. Prospects of low-dimensional and nanostructured silicon-based thermoelectric materials: findings from theory and simulation

    Science.gov (United States)

    Neophytou, Neophytos

    2015-04-01

    Silicon based low-dimensional materials receive significant attention as new generation thermoelectric materials after they have demonstrated record low thermal conductivities. Very few works to-date, however, report significant advances with regards to the power factor. In this review we examine possibilities of power factor enhancement in: (i) low-dimensional Si channels and (ii) nanocrystalline Si materials. For low-dimensional channels we use atomistic simulations and consider ultra-narrow Si nanowires and ultra-thin Si layers of feature sizes below 15 nm. Room temperature is exclusively considered. We show that, in general, low-dimensionality does not offer possibilities for power factor improvement, because although the Seebeck coefficient could slightly increase, the conductivity inevitably degrades at a much larger extend. The power factor in these channels, however, can be optimized by proper choice of geometrical parameters such as the transport orientation, confinement orientation, and confinement length scale. Our simulations show that in the case where room temperature thermal conductivities as low as κ l = 2 W/mK are achieved, the ZT figure of merit of an optimized Si low-dimensional channel could reach values around unity. For the second case of materials, we show that by making effective use of energy filtering, and taking advantage of the inhomogeneity within the nanocrystalline geometry, the underlying potential profile and dopant distribution large improvements in the thermoelectric power factor can be achieved. The paper is intended to be a review of the main findings with regards to the thermoelectric performance of nanoscale Si through our simulation work as well as through recent experimental observations.

  8. Processing and characterization of diatom nanoparticles and microparticles as potential source of silicon for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Le, Thi Duy Hanh [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Bonani, Walter [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Interuniversity Consortium for Science and Technology of Materials, Trento Research Unit, Trento (Italy); Speranza, Giorgio [Center for Materials and Microsystems, PAM-SE, Fondazione Bruno Kessler, Trento (Italy); Sglavo, Vincenzo; Ceccato, Riccardo [Department of Industrial Engineering, University of Trento, Trento (Italy); Maniglio, Devid; Motta, Antonella [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Interuniversity Consortium for Science and Technology of Materials, Trento Research Unit, Trento (Italy); Migliaresi, Claudio, E-mail: claudio.migliaresi@unitn.it [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Interuniversity Consortium for Science and Technology of Materials, Trento Research Unit, Trento (Italy)

    2016-02-01

    Silicon plays an important role in bone formation and maintenance, improving osteoblast cell function and inducing mineralization. Often, bone deformation and long bone abnormalities have been associated with silica/silicon deficiency. Diatomite, a natural deposit of diatom skeleton, is a cheap and abundant source of biogenic silica. The aim of the present study is to validate the potential of diatom particles derived from diatom skeletons as silicon-donor materials for bone tissue engineering applications. Raw diatomite (RD) and calcined diatomite (CD) powders were purified by acid treatments, and diatom microparticles (MPs) and nanoparticles (NPs) were produced by fragmentation of purified diatoms under alkaline conditions. The influence of processing on the surface chemical composition of purified diatomites was evaluated by X-ray photoelectron spectroscopy (XPS). Diatoms NPs were also characterized in terms of morphology and size distribution by transmission electron microscopy (TEM) and Dynamic light scattering (DLS), while diatom MPs morphology was analyzed by scanning electron microscopy (SEM). Surface area and microporosity of the diatom particles were evaluated by nitrogen physisorption methods. Release of silicon ions from diatom-derived particles was demonstrated using inductively coupled plasma optical emission spectrometry (ICP/OES); furthermore, silicon release kinetic was found to be influenced by diatomite purification method and particle size. Diatom-derived microparticles (MPs) and nanoparticles (NPs) showed limited or no cytotoxic effect in vitro depending on the administration conditions. - Highlights: • Diatomite is a natural source of silica and has a potential as silicon-donor for bone regenerative applications. • Diatom particles derived from purified diatom skeletons were prepared by fragmentation under extreme alkaline condition. • Dissolution of diatom particles derived from diatom skeletons in DI water depend on purification method

  9. Processing and characterization of diatom nanoparticles and microparticles as potential source of silicon for bone tissue engineering

    International Nuclear Information System (INIS)

    Le, Thi Duy Hanh; Bonani, Walter; Speranza, Giorgio; Sglavo, Vincenzo; Ceccato, Riccardo; Maniglio, Devid; Motta, Antonella; Migliaresi, Claudio

    2016-01-01

    Silicon plays an important role in bone formation and maintenance, improving osteoblast cell function and inducing mineralization. Often, bone deformation and long bone abnormalities have been associated with silica/silicon deficiency. Diatomite, a natural deposit of diatom skeleton, is a cheap and abundant source of biogenic silica. The aim of the present study is to validate the potential of diatom particles derived from diatom skeletons as silicon-donor materials for bone tissue engineering applications. Raw diatomite (RD) and calcined diatomite (CD) powders were purified by acid treatments, and diatom microparticles (MPs) and nanoparticles (NPs) were produced by fragmentation of purified diatoms under alkaline conditions. The influence of processing on the surface chemical composition of purified diatomites was evaluated by X-ray photoelectron spectroscopy (XPS). Diatoms NPs were also characterized in terms of morphology and size distribution by transmission electron microscopy (TEM) and Dynamic light scattering (DLS), while diatom MPs morphology was analyzed by scanning electron microscopy (SEM). Surface area and microporosity of the diatom particles were evaluated by nitrogen physisorption methods. Release of silicon ions from diatom-derived particles was demonstrated using inductively coupled plasma optical emission spectrometry (ICP/OES); furthermore, silicon release kinetic was found to be influenced by diatomite purification method and particle size. Diatom-derived microparticles (MPs) and nanoparticles (NPs) showed limited or no cytotoxic effect in vitro depending on the administration conditions. - Highlights: • Diatomite is a natural source of silica and has a potential as silicon-donor for bone regenerative applications. • Diatom particles derived from purified diatom skeletons were prepared by fragmentation under extreme alkaline condition. • Dissolution of diatom particles derived from diatom skeletons in DI water depend on purification method

  10. Analytical and experimental evaluation of joining silicon nitride to metal and silicon carbide to metal for advanced heat engine applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S.; Selverian, J.H.; O`Neil, D.; Kim, H. [GTE Labs., Inc., Waltham, MA (US); Kim, K. [Brown Univ., Providence, RI (US). Div. of Engineering

    1993-05-01

    This report summarizes the results of Phase 2 of Analytical and Experimental Evaluation of Joining Silicon Nitride to Metal and Silicon Carbide to Metal for Advanced Heat Engine Applications. A general methodology was developed to optimize the joint geometry and material systems for 650{degrees}C applications. Failure criteria were derived to predict the fracture of the braze and ceramic. Extensive finite element analyses (FEA) were performed to examine various joint geometries and to evaluate the affect of different interlayers on the residual stress state. Also, material systems composed of coating materials, interlayers, and braze alloys were developed for the program based on the chemical stability and strength of the joints during processing, and service. The FEA results were compared with experiments using two methods: (1) an idealized strength relationship of the ceramic, and (2) a probabilistic analysis of the ceramic strength (NASA CARES). The results showed that the measured strength of the joint reached 30--80% of the strength predicted by FEA. Also, potential high-temperature braze alloys were developed and evaluated for the high-temperature application of ceramic-metal joints. 38 tabs, 29 figs, 20 refs.

  11. Engineering Mixed Ionic Electronic Conduction in La 0.8 Sr 0.2 MnO 3+ δ Nanostructures through Fast Grain Boundary Oxygen Diffusivity

    KAUST Repository

    Saranya, Aruppukottai M.

    2015-04-09

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Nanoionics has become an increasingly promising field for the future development of advanced energy conversion and storage devices, such as batteries, fuel cells, and supercapacitors. Particularly, nanostructured materials offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. However, the enhancement of the mass transport properties at the nanoscale has often been found to be difficult to implement in nanostructures. Here, an artificial mixed ionic electronic conducting oxide is fabricated by grain boundary (GB) engineering thin films of La0.8Sr0.2MnO3+δ. This electronic conductor is converted into a good mixed ionic electronic conductor by synthesizing a nanostructure with high density of vertically aligned GBs with high concentration of strain-induced defects. Since this type of GBs present a remarkable enhancement of their oxide-ion mass transport properties (of up to six orders of magnitude at 773 K), it is possible to tailor the electrical nature of the whole material by nanoengineering, especially at low temperatures. The presented results lead to fundamental insights into oxygen diffusion along GBs and to the application of these engineered nanomaterials in new advanced solid state ionics devices such are micro-solid oxide fuel cells or resistive switching memories. An electronic conductor such as La0.8Sr0.2MnO3+δ is converted into a good mixed ionic electronic conductor by synthesizing a nanostructure with excellent electronic and oxygen mass transport properties. Oxygen diffusion highways are created by promoting a high concentration of strain-induced defects in the grain boundary region. This novel strategy opens the way for synthesizing new families of artificial mixed ionic-electronic conductors by design.

  12. Effect of dose and size on defect engineering in carbon cluster implanted silicon wafers

    Science.gov (United States)

    Okuyama, Ryosuke; Masada, Ayumi; Shigematsu, Satoshi; Kadono, Takeshi; Hirose, Ryo; Koga, Yoshihiro; Okuda, Hidehiko; Kurita, Kazunari

    2018-01-01

    Carbon-cluster-ion-implanted defects were investigated by high-resolution cross-sectional transmission electron microscopy toward achieving high-performance CMOS image sensors. We revealed that implantation damage formation in the silicon wafer bulk significantly differs between carbon-cluster and monomer ions after implantation. After epitaxial growth, small and large defects were observed in the implanted region of carbon clusters. The electron diffraction pattern of both small and large defects exhibits that from bulk crystalline silicon in the implanted region. On the one hand, we assumed that the silicon carbide structure was not formed in the implanted region, and small defects formed because of the complex of carbon and interstitial silicon. On the other hand, large defects were hypothesized to originate from the recrystallization of the amorphous layer formed by high-dose carbon-cluster implantation. These defects are considered to contribute to the powerful gettering capability required for high-performance CMOS image sensors.

  13. Surface engineering with ion beams: from self-organized nanostructures to ultra-smooth surfaces

    International Nuclear Information System (INIS)

    Frost, F.; Ziberi, B.; Schindler, A.; Rauschenbach, B.

    2008-01-01

    Low-energy ion-beam sputtering, i.e. the removal of atoms from a surface due to the impact of energetic ions or atoms, is an inherent part of numerous surface processing techniques. Besides the actual removal of material, this surface erosion process often results in a pronounced alteration of the surface topography. Under certain conditions, sputtering results in the formation of well-ordered patterns. This self-organized pattern formation is related to a surface instability between curvature-dependent sputtering that roughens the surface and smoothing by different surface relaxation mechanisms. If the evolution of surface topography is dominated by relaxation mechanisms, surface smoothing can occur. In this presentation the current status of self-organized pattern formation and surface smoothing by low-energy ion-beam erosion of Si and Ge is summarized. In detail it will be shown that a multitude of patterns as well as ultra-smooth surfaces can develop, particularly on Si surfaces. Additionally, the most important experimental parameters that control these processes are discussed. Finally, examples are given for the application of low-energy ion beams as a novel approach for passive optical device engineering for many advanced optical applications. (orig.)

  14. PREFACE: 1st International School and Conference "Saint Petersburg OPEN 2014" on Optoelectronics, Photonics, Engineering and Nanostructures

    Science.gov (United States)

    2014-09-01

    Dear Colleagues, 1st International School and Conference "Saint Petersburg OPEN 2014" on Optoelectronics, Photonics, Engineering and Nanostructures was held on March 25 - 27, 2014 at St. Petersburg Academic University - Nanotechnology Research and Education Centre of the Russian Academy of Sciences. The School and Conference included a series of invited talks given by leading professors with the aim to introduce young scientists with actual problems and major advances in physics and technology. The keynote speakers were: Mikhail Glazov (Ioffe Physico-Technical Institute RAS, Russia) Vladimir Dubrovskii (Saint Petersburg Academic University RAS, Russia) Alexey Kavokin (University of Southampton, United Kingdom and St. Petersburg State University, Russia) Vladimir Korenev (Ioffe Physico-Technical Institute RAS, Russia) Sergey Kukushkin (Institute of Problems of Mechanical Engineering RAS, Russia) Nikita Pikhtin (Ioffe Physico-Technical Institute RAS, Russia and "Elfolum" Ltd., Russia) Dmitry Firsov (Saint Petersburg State Polytechnical University, Russia) During the poster session all undergraduate and graduate students attending the conference presented their works. Sufficiently large number of participants with more than 160 student attendees from all over the world allowed the Conference to provide a fertile ground for the fruitful discussions between the young scientists as well as to become a perfect platform for the valuable discussions between student authors and highly experienced scientists. The best student papers, which were selected by the Program Committee and by the invited speakers basing on the theses and their poster presentation, were awarded with diplomas of the conference - see the photos. This year's School and Conference is supported by SPIE (The International Society for Optics and Photonics), OSA (The Optical Society), St. Petersburg State Polytechnical University and by Skolkovo Foundation. It is a continuation of the annual schools and

  15. Inorganic Glue Enabling High Performance of Silicon Particles as Lithium Ion Battery Anode

    KAUST Repository

    Cui, Li-Feng

    2011-01-01

    Silicon, as an alloy-type anode material, has recently attracted lots of attention because of its highest known Li+ storage capacity (4200 mAh/g). But lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Silicon nanostructures such as nanowires and nanotubes can overcome the pulverization problem, however these nano-engineered silicon anodes usually involve very expensive processes and have difficulty being applied in commercial lithium ion batteries. In this study, we report a novel method using amorphous silicon as inorganic glue replacing conventional polymer binder. This inorganic glue method can solve the loss of contact issue in conventional silicon particle anode and enables successful cycling of various sizes of silicon particles, both nano-particles and micron particles. With a limited capacity of 800 mAh/g, relatively large silicon micron-particles can be stably cycled over 200 cycles. The very cheap production of these silicon particle anodes makes our method promising and competitive in lithium ion battery industry. © 2011 The Electrochemical Society.

  16. Bandgap Engineering of 1300 nm Quantum Dots/Quantum Well Nanostructures Based Devices

    KAUST Repository

    Alhashim, Hala H.

    2016-05-29

    The main objectives of this thesis are to develop viable process and/or device technologies for bandgap tuning of 1300-nm InGaAs/GaAs quantum-dot (QD) laser structures, and broad linewidth 1300-nm InGaAsP/InP quantum well (QW) superluminescent diode structures. The high performance bandgap-engineered QD laser structures were achieved by employing quantum-dot intermixing (QDI) based on impurity free vacancy diffusion (IFVD) technique for eventual seamless active-passive integration, and bandgap-tuned lasers. QDI using various dielectric-capping materials, such as HfO2, SrTiO3, TiO2, Al2O3 and ZnO, etc, were experimented in which the resultant emission wavelength can be blueshifted to ∼ 1100 nm ─ 1200 nm range depending on process conditions. The significant results extracted from the PL characterization were used to perform an extensive laser characterization. The InAs/GaAs quantum-dot lasers with QDs transition energies were blueshifted by ~185 nm, and lasing around ~1070 – 1190 nm was achieved. Furthermore, from the spectral analysis, a simultaneous five-state lasing in the InAs/InGaAs intermixed QD laser was experimentally demonstrated for the first time in the very important wavelength range from 1030 to 1125 nm. The QDI methodology enabled the facile formation of a plethora of devices with various emission wavelengths suitable for a wide range of applications in the infrared. In addition, the wavelength range achieved is also applicable for coherent light generation in the green – yellow – orange visible wavelength band via frequency doubling, which is a cost-effective way of producing compact devices for pico-projectors, semiconductor laser based solid state lighting, etc. [1, 2] In QW-based superluminescent diode, the problem statement lies on achieving a flat-top and ultra-wide emission bandwidth. The approach was to design an inhomogeneous active region with a comparable simultaneous emission from different transition states in the QW stacks, in

  17. Subwavelength engineered fiber-to-chip silicon-on-sapphire interconnects for mid-infrared applications (Conference Presentation)

    Science.gov (United States)

    Alonso-Ramos, Carlos; Han, Zhaohong; Le Roux, Xavier; Lin, Hongtao; Singh, Vivek; Lin, Pao Tai; Tan, Dawn; Cassan, Eric; Marris-Morini, Delphine; Vivien, Laurent; Wada, Kazumi; Hu, Juejun; Agarwal, Anuradha; Kimerling, Lionel C.

    2016-05-01

    The mid-Infrared wavelength range (2-20 µm), so-called fingerprint region, contains the very sharp vibrational and rotational resonances of many chemical and biological substances. Thereby, on-chip absorption-spectrometry-based sensors operating in the mid-Infrared (mid-IR) have the potential to perform high-precision, label-free, real-time detection of multiple target molecules within a single sensor, which makes them an ideal technology for the implementation of lab-on-a-chip devices. Benefiting from the great development realized in the telecom field, silicon photonics is poised to deliver ultra-compact efficient and cost-effective devices fabricated at mass scale. In addition, Si is transparent up to 8 µm wavelength, making it an ideal material for the implementation of high-performance mid-IR photonic circuits. The silicon-on-insulator (SOI) technology, typically used in telecom applications, relies on silicon dioxide as bottom insulator. Unfortunately, silicon dioxide absorbs light beyond 3.6 µm, limiting the usability range of the SOI platform for the mid-IR. Silicon-on-sapphire (SOS) has been proposed as an alternative solution that extends the operability region up to 6 µm (sapphire absorption), while providing a high-index contrast. In this context, surface grating couplers have been proved as an efficient means of injecting and extracting light from mid-IR SOS circuits that obviate the need of cleaving sapphire. However, grating couplers typically have a reduced bandwidth, compared with facet coupling solutions such as inverse or sub-wavelength tapers. This feature limits their feasibility for absorption spectroscopy applications that may require monitoring wide wavelength ranges. Interestingly, sub-wavelength engineering can be used to substantially improve grating coupler bandwidth, as demonstrated in devices operating at telecom wavelengths. Here, we report on the development of fiber-to-chip interconnects to ZrF4 optical fibers and integrated SOS

  18. 3rd International School and Conference “Saint Petersburg OPEN 2016” on Optoelectronics, Photonics, Engineering and Nanostructures

    International Nuclear Information System (INIS)

    2016-01-01

    Dear Colleagues, 3rd International School and Conference “Saint Petersburg OPEN 2016” on Optoelectronics, Photonics, Engineering and Nanostructures was held on March 28 - 30, 2016 at St. Petersburg Academic University of the Russian Academy of Sciences. The School and Conference included a series of invited talks given by leading professors with the aim of introducing young scientists to the actual problems and major advances in modern physics and technology. The keynote speakers were Mircea Guina (Tampere University of Technology, Finland) Evgeny I. Terukov (Ioffe Institute RAS, Russia) Victor M. Ustinov (Ioffe Institute RAS, Russia) Peter G. Kazansky (University of Southampton, UK) Alexander O. Golubok (ITMO University, Russia) Georgy E. Cirlin (St Petersburg Academic University RAS, Russia) Levon V. Asryan (Virginia Polytechnic Institute and State University, USA) Andrey A. Lipovskii (Peter the Great St.Petersburg Polytechnic University, Russia) During the poster session all undergraduate and graduate students attending the conference presented their works. A large number of participants with more than 280 student attendees from all over the world allowed the Conference to provide a fertile ground for the fruitful discussions between the young scientists as well as to become a perfect platform for the valuable discussions between student authors and highly experienced scientists. The best student papers, which were selected by the Program Committee and by the invited speakers based on the theses and their poster presentation, were awarded with diplomas of the conference - see the photos. This year “Saint Petersburg OPEN 2016” is organized by St. Petersburg Academic University in cooperation with Peter the Great St. Petersburg Polytechnic University. The School and Conference is supported by the Russian Foundation for Basic Research (Project N 16-32-10060) , Russian Science Foundation, SPIE (The International Society for Optics and Photonics) and OSA (The

  19. Engineering of silicon/HfO{sub 2} interface by variable energy proton irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, Savita, E-mail: mauryasavita5@gmail.com; Maringanti, Radhakrishna [Division of Electronics and Microelectronics, Indian Institute of Information Technology, Allahabad, Uttar Pradesh 211012 (India); Tribedi, L. C. [DNAP, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005 (India)

    2014-08-18

    Surfaces and interfaces between materials are of paramount importance for various phenomena, such as painting a house, catalyst driven chemical reactions, intricate life processes, corrosion of materials, and fabrication of various semiconductor devices. Interface of silicon or other such substrates with any of the oxides has profound effect on the performance of metal oxide field effect transistors and other similar devices. Since a surface is an abrupt termination of a periodic crystal, surface atoms will have some unsaturated valence electrons and these unsaturated bonds at the semiconductor surface make it chemically highly reactive. Other than annealing, there is not much that can be done to manage these unsaturated bonds. This study was initiated to explore the possibility of repairing these unsaturated dangling bonds that are formed at the silicon and oxide interface during the deposition of oxide layer above silicon, by the use of proton irradiation. In order to improve the interface characteristics, we present a method to modify the interface of silicon and hafnium dioxide after its fabrication, through proton irradiation. Results of the study are promising and probably this method might be used along with other methods such as annealing to modify the interface, after its fabrication.

  20. Engineering of silicon/HfO2 interface by variable energy proton irradiation

    Science.gov (United States)

    Maurya, Savita; Tribedi, L. C.; Maringanti, Radhakrishna

    2014-08-01

    Surfaces and interfaces between materials are of paramount importance for various phenomena, such as painting a house, catalyst driven chemical reactions, intricate life processes, corrosion of materials, and fabrication of various semiconductor devices. Interface of silicon or other such substrates with any of the oxides has profound effect on the performance of metal oxide field effect transistors and other similar devices. Since a surface is an abrupt termination of a periodic crystal, surface atoms will have some unsaturated valence electrons and these unsaturated bonds at the semiconductor surface make it chemically highly reactive. Other than annealing, there is not much that can be done to manage these unsaturated bonds. This study was initiated to explore the possibility of repairing these unsaturated dangling bonds that are formed at the silicon and oxide interface during the deposition of oxide layer above silicon, by the use of proton irradiation. In order to improve the interface characteristics, we present a method to modify the interface of silicon and hafnium dioxide after its fabrication, through proton irradiation. Results of the study are promising and probably this method might be used along with other methods such as annealing to modify the interface, after its fabrication.

  1. Coaxial electrospun aligned tussah silk fibroin nanostructured fiber scaffolds embedded with hydroxyapatite–tussah silk fibroin nanoparticles for bone tissue engineering

    International Nuclear Information System (INIS)

    Shao, Weili; He, Jianxin; Sang, Feng; Ding, Bin; Chen, Li; Cui, Shizhong; Li, Kejing; Han, Qiming; Tan, Weilin

    2016-01-01

    The bone is a composite of inorganic and organic materials and possesses a complex hierarchical architecture consisting of mineralized fibrils formed by collagen molecules and coated with oriented hydroxyapatite. To regenerate bone tissue, it is necessary to provide a scaffold that mimics the architecture of the extracellular matrix in native bone. Here, we describe one such scaffold, a nanostructured composite with a core made of a composite of hydroxyapatite and tussah silk fibroin. The core is encased in a shell of tussah silk fibroin. The composite fibers were fabricated by coaxial electrospinning using green water solvent and were characterized using different techniques. In comparison to nanofibers of pure tussah silk, composite notably improved mechanical properties, with 90-fold and 2-fold higher initial modulus and breaking stress, respectively, obtained. Osteoblast-like MG-63 cells were cultivated on the composite to assess its suitability as a scaffold for bone tissue engineering. We found that the fiber scaffold supported cell adhesion and proliferation and functionally promoted alkaline phosphatase and mineral deposition relevant for biomineralization. In addition, the composite were more biocompatible than pure tussah silk fibroin or cover slip. Thus, the nanostructured composite has excellent biomimetic and mechanical properties and is a potential biocompatible scaffold for bone tissue engineering. - Highlights: • A designing scaffold strategy to imitate the mineralized collagen bundles in natural bone was presented. • Aligned nanostructured composite fibers were fabricated by coaxial electrospinning using green water solvent. • Mechanical properties of aligned TSF nanofiber had been significantly improved by embedding with composite nanoparticles. • Composite scaffolds effectively supported proliferation of MG-63 cells and promoted biomineralization.

  2. Investigations on structural and multiferroic properties of artificially engineered lead zirconate titanate-cobalt iron oxide layered nanostructures

    Science.gov (United States)

    Ortega Achury, Nora Patricia

    Mutiferroics are a novel class of next generation multifunctional materials, which display simultaneous magnetic, electric, and ferroelastic ordering, have drawn increasing interest due to their multi-functionality for a variety of device applications. Since, very rare single phase materials exist in nature this kind of properties, an intensive research activity is being pursued towards the development of new engineered materials with strong magneto-electric (ME) coupling. In the present investigation, we have fabricated polycrystalline and highly oriented PbZr0.53,Ti0.47O3--CoFe 2O4 (PZT/CFO) artificially multilayers (MLs) engineered nanostructures thin films which were grown on Pt/TiO2/SiO2/Si and La 0.5Sr0.5CoO3 (LSCO) coated (001) MgO substrates respectively, using the pulsed laser deposition technique. The effect of various PZT/CFO sandwich configurations having 3, 5, and 9 layers, while maintaining similar total PZT and CFO thickness, has been systematically investigated. The first part of this thesis is devoted to the analysis of structural and microstructure properties of the PZT/CFO MLs. X-ray diffraction (XRD) and micro Raman analysis revealed that PZT and CFO were in the perovskite and spinel phases respectively in the all layered nanostructure, without any intermediate phase. The TEM and STEM line scan of the ML thin films showed that the layered structure was maintained with little inter-diffusion near the interfaces at nano-metric scale without any impurity phase, however better interface was observed in highly oriented films. Second part of this dissertation was dedicated to study of the dielectric, impedance, modulus, and conductivity spectroscopies. These measurements were carried out over a wide range of temperatures (100 K to 600 K) and frequencies (100 Hz to 1 MHz) to investigate the grain and grain boundary effects on electrical properties of MLs. The temperature dependent dielectric and loss tangent illustrated step-like behavior and

  3. Coaxial electrospun aligned tussah silk fibroin nanostructured fiber scaffolds embedded with hydroxyapatite-tussah silk fibroin nanoparticles for bone tissue engineering.

    Science.gov (United States)

    Shao, Weili; He, Jianxin; Sang, Feng; Ding, Bin; Chen, Li; Cui, Shizhong; Li, Kejing; Han, Qiming; Tan, Weilin

    2016-01-01

    The bone is a composite of inorganic and organic materials and possesses a complex hierarchical architecture consisting of mineralized fibrils formed by collagen molecules and coated with oriented hydroxyapatite. To regenerate bone tissue, it is necessary to provide a scaffold that mimics the architecture of the extracellular matrix in native bone. Here, we describe one such scaffold, a nanostructured composite with a core made of a composite of hydroxyapatite and tussah silk fibroin. The core is encased in a shell of tussah silk fibroin. The composite fibers were fabricated by coaxial electrospinning using green water solvent and were characterized using different techniques. In comparison to nanofibers of pure tussah silk, composite notably improved mechanical properties, with 90-fold and 2-fold higher initial modulus and breaking stress, respectively, obtained. Osteoblast-like MG-63 cells were cultivated on the composite to assess its suitability as a scaffold for bone tissue engineering. We found that the fiber scaffold supported cell adhesion and proliferation and functionally promoted alkaline phosphatase and mineral deposition relevant for biomineralization. In addition, the composite were more biocompatible than pure tussah silk fibroin or cover slip. Thus, the nanostructured composite has excellent biomimetic and mechanical properties and is a potential biocompatible scaffold for bone tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Stable configurations of graphene on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Javvaji, Brahmanandam; Shenoy, Bhamy Maithry [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Mahapatra, D. Roy, E-mail: droymahapatra@aero.iisc.ernet.in [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Ravikumar, Abhilash [Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025 (India); Hegde, G.M. [Center for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012 (India); Rizwan, M.R. [Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025 (India)

    2017-08-31

    Highlights: • Simulations of epitaxial growth process for silicon–graphene system is performed. • Identified the most favourable orientation of graphene sheet on silicon substrate. • Atomic local strain due to the silicon–carbon bond formation is analyzed. - Abstract: Integration of graphene on silicon-based nanostructures is crucial in advancing graphene based nanoelectronic device technologies. The present paper provides a new insight on the combined effect of graphene structure and silicon (001) substrate on their two-dimensional anisotropic interface. Molecular dynamics simulations involving the sub-nanoscale interface reveal a most favourable set of temperature independent orientations of the monolayer graphene sheet with an angle of ∽15° between its armchair direction and [010] axis of the silicon substrate. While computing the favorable stable orientations, both the translation and the rotational vibrations of graphene are included. The possible interactions between the graphene atoms and the silicon atoms are identified from their coordination. Graphene sheet shows maximum bonding density with bond length 0.195 nm and minimum bond energy when interfaced with silicon substrate at 15° orientation. Local deformation analysis reveals probability distribution with maximum strain levels of 0.134, 0.047 and 0.029 for 900 K, 300 K and 100 K, respectively in silicon surface for 15° oriented graphene whereas the maximum probable strain in graphene is about 0.041 irrespective of temperature. Silicon–silicon dimer formation is changed due to silicon–carbon bonding. These results may help further in band structure engineering of silicon–graphene lattice.

  5. Nanostructuring of Solar Cell Surfaces

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    Solar energy is by far the most abundant renewable energy source available, but the levelized cost of solar energy is still not competitive with that of fossil fuels. Therefore there is a need to improve the power conversion effciency of solar cells without adding to the production cost. The main...... objective of this PhD thesis is to develop nanostructured silicon (Si) solar cells with higher power conversion efficiency using only scalable and cost-efficient production methods. The nanostructures, known as 'black silicon', are fabricated by single-step, maskless reactive ion etching and used as front...... texturing of different Si solar cells. Theoretically the nanostructure topology may be described as a graded refractive index in a mean-field approximation between air and Si. The optical properties of the developed black Si were simulated and experimentally measured. Total AM1.5G-weighted average...

  6. Theoretical Prediction of an Antimony-Silicon Monolayer (penta-Sb2Si): Band Gap Engineering by Strain Effect

    Science.gov (United States)

    Morshedi, Hosein; Naseri, Mosayeb; Hantehzadeh, Mohammad Reza; Elahi, Seyed Mohammad

    2018-04-01

    In this paper, using a first principles calculation, a two-dimensional structure of silicon-antimony named penta-Sb2Si is predicted. The structural, kinetic, and thermal stabilities of the predicted monolayer are confirmed by the cohesive energy calculation, phonon dispersion analysis, and first principles molecular dynamic simulation, respectively. The electronic properties investigation shows that the pentagonal Sb2Si monolayer is a semiconductor with an indirect band gap of about 1.53 eV (2.1 eV) from GGA-PBE (PBE0 hybrid functional) calculations which can be effectively engineered by employing external biaxial compressive and tensile strain. Furthermore, the optical characteristics calculation indicates that the predicted monolayer has considerable optical absorption and reflectivity in the ultraviolet region. The results suggest that a Sb2Si monolayer has very good potential applications in new nano-optoelectronic devices.

  7. Follow the Money: Engineering at Stanford and UC Berkeley during the Rise of Silicon Valley

    Science.gov (United States)

    Adams, Stephen B.

    2009-01-01

    A comparison of the engineering schools at UC Berkeley and Stanford during the 1940s and 1950s shows that having an excellent academic program is necessary but not sufficient to make a university entrepreneurial (an engine of economic development). Key factors that made Stanford more entrepreneurial than Cal during this period were superior…

  8. Defect engineering in Czochralski silicon by electron irradiation at different temperatures

    Science.gov (United States)

    Lindström, J. L.; Murin, L. I.; Hallberg, T.; Markevich, V. P.; Svensson, B. G.; Kleverman, M.; Hermansson, J.

    2002-01-01

    Infrared absorption studies of defect formation in Czochralski silicon irradiated with fast electrons in a wide range of temperatures (80-900 K) have been performed. The samples with different contents of oxygen ( 16O, 18O) and carbon ( 12C, 13C) isotopes were investigated. The main defect reactions are found to depend strongly on irradiation temperature and dose, as well as on impurity content and pre-history of the samples. Some new radiation-induced defects are revealed after irradiation at elevated temperatures as well as after a two-step (hot + room-temperature (RT)) irradiation.

  9. Defect engineering in Czochralski silicon by electron irradiation at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lindstroem, J.L. E-mail: lennart.lindstrom@ftf.lth.se; Murin, L.I.; Hallberg, T.; Markevich, V.P.; Svensson, B.G.; Kleverman, M.; Hermansson, J

    2002-01-01

    Infrared absorption studies of defect formation in Czochralski silicon irradiated with fast electrons in a wide range of temperatures (80-900 K) have been performed. The samples with different contents of oxygen ({sup 16}O,{sup 18}O) and carbon ({sup 12}C,{sup 13}C) isotopes were investigated. The main defect reactions are found to depend strongly on irradiation temperature and dose, as well as on impurity content and pre-history of the samples. Some new radiation-induced defects are revealed after irradiation at elevated temperatures as well as after a two-step (hot + room-temperature (RT)) irradiation.

  10. Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

    Science.gov (United States)

    Hwang, Jangsun; Hwang, Mintai P.; Choi, Moonhyun; Seo, Youngmin; Jo, Yeonho; Son, Jaewoo; Hong, Jinkee; Choi, Jonghoon

    2016-10-01

    Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu2+), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu2+ at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation. The resulting alkyl-terminated porous silicon nanoparticles (APS NPs) have enhanced fluorescence stability and intensity, and importantly, exhibit [Cu2+]-dependent quenching of fluorescence. After determining various aqueous sensing conditions for Cu2+, we demonstrate the use of APS NPs in two separate applications - a standard well-based paper kit and a portable layer-by-layer stick kit. Collectively, we demonstrate the potential of APS NPs in sensors for the effective detection of Cu2+.

  11. Patterning the molecular printboard: patterning cyclodextrin monolayers on silicon oxide using nanoimprint lithography and its application in 3D multilayer nanostructuring

    International Nuclear Information System (INIS)

    Maury, Pascale; Peter, Maria; Crespo-Biel, Olga; Ling, Xing Yi; Reinhoudt, David N; Huskens, Jurriaan

    2007-01-01

    An accurate and versatile process for the fabrication of high-resolution 3D nanostructures combining top-down and bottom-up nanofabrication schemes is described here. The method is based on layer-by-layer (LBL) assembly of functionalized nanoparticles (NPs) bound together by means of supramolecular interactions between a layer of adamantyl-functionalized dendrimers, the guest, and cyclodextrin (CD)-functionalized nanoparticles, the host. First, a self-assembled CD monolayer (CD SAM) was patterned using nanoimprint lithography (NIL) and later used to anchor supramolecular LBL assemblies onto it. The versatility of the process was demonstrated by using NPs of different size and nature. Two types of LBL assemblies were fabricated based on (i) 2.8 nm CD-functionalized Au NPs, which allow an accurate height control and (ii) 60 nm CD-functionalized SiO 2 particles, which permit the fabrication of nanostructures. In one of the cases vertical deposition was used to obtain high particle ordering. Both types of NP were used to produce nanostructured LBL assemblies with lateral sizes below 100 nm. Physical confinement was observed when using 60 nm CD-functionalized SiO 2 particles in the sub-300 nm scale on the first and second bilayers. Finally, periodic patterns of single nanoparticles were achieved

  12. Superhydrophilic nanostructure

    Science.gov (United States)

    Mao, Samuel S; Zormpa, Vasileia; Chen, Xiaobo

    2015-05-12

    An embodiment of a superhydrophilic nanostructure includes nanoparticles. The nanoparticles are formed into porous clusters. The porous clusters are formed into aggregate clusters. An embodiment of an article of manufacture includes the superhydrophilic nanostructure on a substrate. An embodiment of a method of fabricating a superhydrophilic nanostructure includes applying a solution that includes nanoparticles to a substrate. The substrate is heated to form aggregate clusters of porous clusters of the nanoparticles.

  13. Interfacial engineering of CuO nanorod/ZnO nanowire hybrid nanostructure photoanode in dye-sensitized solar cell

    Science.gov (United States)

    Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Baran, Sümeyra Seniha; Asgin, Mansur; Gur, Emre; Kocak, Yusuf

    2018-01-01

    Developing efficient and cost-effective photoanode plays a vital role determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Here, we demonstrate DSSCs that achieve relatively high power conversion efficiencies (PCEs) by using one-dimensional (1D) zinc oxide (ZnO) nanowires and copper (II) oxide (CuO) nanorods hybrid nanostructures. CuO nanorod-based thin films were prepared by hydrothermal method and used as a blocking layer on top of the ZnO nanowires' layer. The use of 1D ZnO nanowire/CuO nanorod hybrid nanostructures led to an exceptionally high photovoltaic performance of DSSCs with a remarkably high open-circuit voltage (0.764 V), short current density (14.76 mA/cm2 under AM1.5G conditions), and relatively high solar to power conversion efficiency (6.18%) . The enhancement of the solar to power conversion efficiency can be explained in terms of the lag effect of the interfacial recombination dynamics of CuO nanorod-blocking layer on ZnO nanowires. This work shows more economically feasible method to bring down the cost of the nano-hybrid cells and promises for the growth of other important materials to further enhance the solar to power conversion efficiency.

  14. The role of silicon on the microstructure and magnetic behaviour of nanostructured (Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} powders

    Energy Technology Data Exchange (ETDEWEB)

    Hocine, M. [Département de Génie Mécanique, Faculté de Technologies, Université de M' sila, B.P 166 Ichbelia, M' sila (Algeria); UR-MPE, M' hamed Bougara University, Boumerdes, 35000 Algeria (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 02Bd Frantz Fanon, BP 399, Alger-Gare, Algiers (Algeria); Hemmous, M. [Nuclear Research Centre of Algiers, 02Bd Frantz Fanon, BP 399, Alger-Gare, Algiers (Algeria); Martínez-Blanco, D. [SCTs, University of Oviedo, EPM, Mieres, 33600 Spain (Spain); Gorria, P. [Department of Physics, EPI, University of Oviedo, Gijón, 33203 Spain (Spain); Rahal, B. [Nuclear Research Centre of Algiers, 02Bd Frantz Fanon, BP 399, Alger-Gare, Algiers (Algeria); Blanco, J.A. [Department of Physics, University of Oviedo, CalvoSotelo St., Oviedo, 330 07 Spain (Spain); Sunol, J.J. [Departament de Fisica, Universitat de Girona, Campus de Montillivi, Girona, 17071 Spain (Spain); Laggoun, A. [UR-MPE, M' hamed Bougara University, Boumerdes, 35000 Algeria (Algeria)

    2017-01-15

    Single-phase(Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} nanostructured powders (x=0,5, 10, 15 and 20) have been elaborated by mechanical alloying in order to investigate the effect of silicon on the microstructure and magnetic properties of these alloys. A disordered Fe(Co, Si) solid solution with body centred cubic (bcc) crystal structure is formed after 72 h of milling for all the compositions. The addition of Si gives rise to a progressive decrease of the lattice parameter, from about 2.865 Å for the binary Fe{sub 70}Co{sub 30} compound down to 2.841 Å for the powder with x=20. The sample with the uppermost Si content exhibits the lowest value for the mean grain size (≈10 nm) as well as the largest microstrain (above 1.1%). All the samples are ferromagnetic at room temperature, although the saturation magnetization value reduces almost linearly by adding Si to the composition. A similar trend is observed for the hyperfine magnetic field obtained from the analysis of the room temperature Mössbauer spectra. The hyperfine field distributions show a broad double-peak shape for x>0, which can be ascribed to multiple local environments for the Fe atoms inside a disordered solid solution. - Highlights: • Single-phase (Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} nanostructured powders (x=0, 5, 10, 15 and 20) have been elaborated by mechanical alloying. • The sample with the uppermost Si content exhibits the lowest value for the mean grain size. • The magnetic and hyperfine parameters of (Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} depended intimately on Si content.

  15. Nanostructured superconductors

    National Research Council Canada - National Science Library

    Moshchalkov, V. V; Fritzsche, Joachim

    2011-01-01

    ... through nanostructuring and for developing a variety of novel fluxonics devices based on vortex manipulation. Nanostructuring can, in fact, create such conditions for the flux pinning by arrays of nanofabricated antidots or magnetic dots, which could maximize the second important superconducting critical parameter (critical current) up to its theoretical limit ...

  16. Engineering the thermal conductivity along an individual silicon nanowire by selective helium ion irradiation

    Science.gov (United States)

    Zhao, Yunshan; Liu, Dan; Chen, Jie; Zhu, Liyan; Belianinov, Alex; Ovchinnikova, Olga S.; Unocic, Raymond R.; Burch, Matthew J.; Kim, Songkil; Hao, Hanfang; Pickard, Daniel S.; Li, Baowen; Thong, John T. L.

    2017-06-01

    The ability to engineer the thermal conductivity of materials allows us to control the flow of heat and derive novel functionalities such as thermal rectification, thermal switching and thermal cloaking. While this could be achieved by making use of composites and metamaterials at bulk length-scales, engineering the thermal conductivity at micro- and nano-scale dimensions is considerably more challenging. In this work, we show that the local thermal conductivity along a single Si nanowire can be tuned to a desired value (between crystalline and amorphous limits) with high spatial resolution through selective helium ion irradiation with a well-controlled dose. The underlying mechanism is understood through molecular dynamics simulations and quantitative phonon-defect scattering rate analysis, where the behaviour of thermal conductivity with dose is attributed to the accumulation and agglomeration of scattering centres at lower doses. Beyond a threshold dose, a crystalline-amorphous transition was observed.

  17. Engineering the thermal conductivity along an individual silicon nanowire by selective helium ion irradiation.

    Science.gov (United States)

    Zhao, Yunshan; Liu, Dan; Chen, Jie; Zhu, Liyan; Belianinov, Alex; Ovchinnikova, Olga S; Unocic, Raymond R; Burch, Matthew J; Kim, Songkil; Hao, Hanfang; Pickard, Daniel S; Li, Baowen; Thong, John T L

    2017-06-27

    The ability to engineer the thermal conductivity of materials allows us to control the flow of heat and derive novel functionalities such as thermal rectification, thermal switching and thermal cloaking. While this could be achieved by making use of composites and metamaterials at bulk length-scales, engineering the thermal conductivity at micro- and nano-scale dimensions is considerably more challenging. In this work, we show that the local thermal conductivity along a single Si nanowire can be tuned to a desired value (between crystalline and amorphous limits) with high spatial resolution through selective helium ion irradiation with a well-controlled dose. The underlying mechanism is understood through molecular dynamics simulations and quantitative phonon-defect scattering rate analysis, where the behaviour of thermal conductivity with dose is attributed to the accumulation and agglomeration of scattering centres at lower doses. Beyond a threshold dose, a crystalline-amorphous transition was observed.

  18. Engineering and Optimization of Silicon-Iron-Manganese Nanoalloy Electrode for Enhanced Lithium-Ion Battery

    Science.gov (United States)

    Alaboina, Pankaj K.; Cho, Jong-Soo; Cho, Sung-Jin

    2017-10-01

    The electrochemical performance of a battery is considered to be primarily dependent on the electrode material. However, engineering and optimization of electrodes also play a crucial role, and the same electrode material can be designed to offer significantly improved batteries. In this work, Si-Fe-Mn nanomaterial alloy (Si/alloy) and graphite composite electrodes were densified at different calendering conditions of 3, 5, and 8 tons, and its influence on electrode porosity, electrolyte wettability, and long-term cycling was investigated. The active material loading was maintained very high ( 2 mg cm-2) to implement electrode engineering close to commercial loading scales. The densification was optimized to balance between the electrode thickness and wettability to enable the best electrochemical properties of the Si/alloy anodes. In this case, engineering and optimizing the Si/alloy composite electrodes to 3 ton calendering (electrode densification from 0.39 to 0.48 g cm-3) showed enhanced cycling stability with a high capacity retention of 100% over 100 cycles. [Figure not available: see fulltext.

  19. Patterning human neuronal networks on photolithographically engineered silicon dioxide substrates functionalized with glial analogues.

    Science.gov (United States)

    Hughes, Mark A; Brennan, Paul M; Bunting, Andrew S; Cameron, Katherine; Murray, Alan F; Shipston, Mike J

    2014-05-01

    Interfacing neurons with silicon semiconductors is a challenge being tackled through various bioengineering approaches. Such constructs inform our understanding of neuronal coding and learning and ultimately guide us toward creating intelligent neuroprostheses. A fundamental prerequisite is to dictate the spatial organization of neuronal cells. We sought to pattern neurons using photolithographically defined arrays of polymer parylene-C, activated with fetal calf serum. We used a purified human neuronal cell line [Lund human mesencephalic (LUHMES)] to establish whether neurons remain viable when isolated on-chip or whether they require a supporting cell substrate. When cultured in isolation, LUHMES neurons failed to pattern and did not show any morphological signs of differentiation. We therefore sought a cell type with which to prepattern parylene regions, hypothesizing that this cellular template would enable secondary neuronal adhesion and network formation. From a range of cell lines tested, human embryonal kidney (HEK) 293 cells patterned with highest accuracy. LUHMES neurons adhered to pre-established HEK 293 cell clusters and this coculture environment promoted morphological differentiation of neurons. Neurites extended between islands of adherent cell somata, creating an orthogonally arranged neuronal network. HEK 293 cells appear to fulfill a role analogous to glia, dictating cell adhesion, and generating an environment conducive to neuronal survival. We next replaced HEK 293 cells with slower growing glioma-derived precursors. These primary human cells patterned accurately on parylene and provided a similarly effective scaffold for neuronal adhesion. These findings advance the use of this microfabrication-compatible platform for neuronal patterning. Copyright © 2013 Wiley Periodicals, Inc.

  20. Influence of silicon and atomic order on the magnetic properties of (Fe{sub 80}Al{sub 20}){sub 100}-{sub x}Si{sub x} nanostructured system

    Energy Technology Data Exchange (ETDEWEB)

    Velez, G. Y., E-mail: gyovelca@univalle.edu.co; Perez Alcazar, G. A.; Zamora, Ligia E. [Universidad del Valle, Departamento de Fisica (Colombia); Romero, J. J.; Martinez, A. [Instituto de Magnetismo Aplicado IMA (Spain)

    2010-01-15

    Mechanically alloyed (Fe{sub 80}Al{sub 20}){sub 100-x}Si{sub x} alloys (with x = 0, 10, 15 and 20) were prepared by using a high energy planetary ball mill, with milling times of 12, 24 and 36 h. The structural and magnetic study was conducted by X-rays diffraction and Moessbauer spectrometry. The system is nanostructured and presents only the BCC disordered phase, whose lattice parameter remains constant with milling time, and decreases when the Si content increases. We found that lattice contraction is influenced 39% by the iron substitution and 61% by the aluminum substitution, by silicon atoms. The Moessbauer spectra and their respective hyperfine magnetic field distributions show that for every milling time used here, the ferromagnetism decreases when x increases. For samples with x {>=} 15 a paramagnetic component appears. From the shape of the magnetic field distributions we stated that the larger ferromagnetic phase observed in the samples alloyed during 24 and 36 h is a consequence of the structural disorder induced by mechanical alloying.

  1. A theoretical study on the optical properties of black silicon

    Science.gov (United States)

    Ma, Shijun; Liu, Shuang; Xu, Qinwei; Xu, Junwen; Lu, Rongguo; Liu, Yong; Zhong, Zhiyong

    2018-03-01

    There is a wide application prospect in black silicon, especially in solar cells and photoelectric detectors. For further optimization of black silicon, it is important to study its optical properties. Especially, the influence of the surface nanostructures on these properties and the light propagation within the nanostructures are relevant. In this paper, two kinds of black silicon models are studied via the finite differences time domain method. The simulated reflectance spectra matches well with the measured curve. Also, the light intensity distribution within the nanostructures shows that near 80% of the incident light are redirected and subjected to internal reflection, which provides powerful support for the good light trapping properties of black silicon.

  2. The chemistry of silicon

    CERN Document Server

    Rochow, E G; Emeléus, H J; Nyholm, Ronald

    1975-01-01

    Pergamon Texts in Organic Chemistry, Volume 9: The Chemistry of Silicon presents information essential in understanding the chemical properties of silicon. The book first covers the fundamental aspects of silicon, such as its nuclear, physical, and chemical properties. The text also details the history of silicon, its occurrence and distribution, and applications. Next, the selection enumerates the compounds and complexes of silicon, along with organosilicon compounds. The text will be of great interest to chemists and chemical engineers. Other researchers working on research study involving s

  3. Surface Engineering of Porous Silicon Microparticles for Intravitreal Sustained Delivery of Rapamycin

    Science.gov (United States)

    Nieto, Alejandra; Hou, Huiyuan; Moon, Sang Woong; Sailor, Michael J.; Freeman, William R.; Cheng, Lingyun

    2015-01-01

    Purpose. To understand the relationship between rapamycin loading/release and surface chemistries of porous silicon (pSi) to optimize pSi-based intravitreal delivery system. Methods. Three types of surface chemical modifications were studied: (1) pSi-COOH, containing 10-carbon aliphatic chains with terminal carboxyl groups grafted via hydrosilylation of undecylenic acid; (2) pSi-C12, containing 12-carbon aliphatic chains grafted via hydrosilylation of 1-dodecene; and (3) pSiO2-C8, prepared by mild oxidation of the pSi particles followed by grafting of 8-hydrocarbon chains to the resulting porous silica surface via a silanization. Results. The efficiency of rapamycin loading follows the order (micrograms of drug/milligrams of carrier): pSiO2-C8 (105 ± 18) > pSi-COOH (68 ± 8) > pSi-C12 (36 ± 6). Powder X-ray diffraction data showed that loaded rapamycin was amorphous and dynamic drug-release study showed that the availability of the free drug was increased by 6-fold (compared with crystalline rapamycin) by using pSiO2-C8 formulation (P = 0.0039). Of the three formulations in this study, pSiO2-C8-RAP showed optimal performance in terms of simultaneous release of the active drug and carrier degradation, and drug-loading capacity. Released rapamycin was confirmed with the fingerprints of the mass spectrometry and biologically functional as the control of commercial crystalline rapamycin. Single intravitreal injections of 2.9 ± 0.37 mg pSiO2-C8-RAP into rabbit eyes resulted in more than 8 weeks of residence in the vitreous while maintaining clear optical media and normal histology of the retina in comparison to the controls. Conclusions. Porous silicon–based rapamycin delivery system using the pSiO2-C8 formulation demonstrated good ocular compatibility and may provide sustained drug release for retina. PMID:25613937

  4. 800 C Silicon Carbide (SiC) Pressure Sensors for Engine Ground Testing

    Science.gov (United States)

    Okojie, Robert S.

    2016-01-01

    MEMS-based 4H-SiC piezoresistive pressure sensors have been demonstrated at 800 C, leading to the discovery of strain sensitivity recovery with increasing temperatures above 400 C, eventually achieving up to, or near, 100 recovery of the room temperature values at 800 C. This result will allow the insertion of highly sensitive pressure sensors closer to jet, rocket, and hypersonic engine combustion chambers to improve the quantification accuracy of combustor dynamics, performance, and increase safety margin. Also, by operating at higher temperature and locating closer to the combustion chamber, reduction of the length (weight) of pressure tubes that are currently used will be achieved. This will result in reduced costlb to access space.

  5. Radiation-Engineered Functionalized Nanogels as Platform for Biomedical Nanocarriers and Bio-Hybrid, Hierarchically Assembled Nanostructures

    International Nuclear Information System (INIS)

    Dispenza, C.; Sabatino, M.-A.; Alessi, S.; Spadaro, G.

    2011-01-01

    Radiation technologies can be considered as choice methodologies for the creation of new functional materials at the nanoscale, the challenge being now the integration of these and other novel nanomaterials into new materials and products. The possibility of generating nanoscalar PVP-based hydrogels particles, with reactive functional groups for subsequent bioconjugation, using industrial type accelerators has been demonstrated. These functional nanoparticles are under evaluation as nanocarriers for targeted release of drugs, but can also be considered as useful building blocks for the assembly of nanostructured materials with controlled architecture. In particular, molecular recognition strategies can be developed to tailor the structural and functional properties of the composite by attaching complementary sequences of molecules from biological source (peptides or oligonucleotides) that will tie nanoparticles together. Under the present CRP, biodegradable nanoparticles will be developed using xyloglucan, a relatively inexpensive polysaccharide as base material, in alternative to PVP. Chemical modification of xyloglucan will be attempted with the purpose of generating radiation cleavable crosslinked micro/nanoparticles. These micro/nanoparticles will incorporate stabilizers (antioxidants, such as quercetin) or pro-degrading agents (enzymes) and will be either dispersed into a biodegradable film forming polymer or self-assembled to form a supramolecular networked film or scaffold. For the purpose, suitable surface modification will be pursued either to promote compatibilisation with the matrix polymer or to efficiently drive the self-assembly process. UV or quantum beam irradiation will be investigated as trigger for the release of the entrapped actives from micro/nanoparticles. (author)

  6. Nanostructured thin films and coatings functional properties

    CERN Document Server

    Zhang, Sam

    2010-01-01

    The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

  7. Proposal of a neutron transmutation doping facility for n-type spherical silicon solar cell at high-temperature engineering test reactor.

    Science.gov (United States)

    Ho, Hai Quan; Honda, Yuki; Motoyama, Mizuki; Hamamoto, Shimpei; Ishii, Toshiaki; Ishitsuka, Etsuo

    2018-05-01

    The p-type spherical silicon solar cell is a candidate for future solar energy with low fabrication cost, however, its conversion efficiency is only about 10%. The conversion efficiency of a silicon solar cell can be increased by using n-type silicon semiconductor as a substrate. This study proposed a new method of neutron transmutation doping silicon (NTD-Si) for producing the n-type spherical solar cell, in which the Si-particles are irradiated directly instead of the cylinder Si-ingot as in the conventional NTD-Si. By using a 'screw', an identical resistivity could be achieved for the Si-particles without a complicated procedure as in the NTD with Si-ingot. Also, the reactivity and neutron flux swing could be kept to a minimum because of the continuous irradiation of the Si-particles. A high temperature engineering test reactor (HTTR), which is located in Japan, was used as a reference reactor in this study. Neutronic calculations showed that the HTTR has a capability to produce about 40t/EFPY of 10Ωcm resistivity Si-particles for fabrication of the n-type spherical solar cell. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Porous Silicon Nanowires

    Science.gov (United States)

    Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

    2011-01-01

    In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline porous silicon nanowires. The growth of porous silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The porous silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999

  9. Highly Efficient and Stable Organic Solar Cells via Interface Engineering with a Nanostructured ITR-GO/PFN Bilayer Cathode Interlayer

    Directory of Open Access Journals (Sweden)

    Ding Zheng

    2017-08-01

    Full Text Available An innovative bilayer cathode interlayer (CIL with a nanostructure consisting of in situ thermal reduced graphene oxide (ITR-GO and poly[(9,9-bis(3′-(N,N-dimethylamionpropyl-2,7-fluorene-alt-2,7-(9,9-dioctyl fluorene] (PFN has been fabricated for inverted organic solar cells (OSCs. An approach to prepare a CIL of high electronic quality by using ITR-GO as a template to modulate the morphology of the interface between the active layer and electrode and to further reduce the work function of the electrode has also been realized. This bilayer ITR-GO/PFN CIL is processed by a spray-coating method with facile in situ thermal reduction. Meanwhile, the CIL shows a good charge transport efficiency and less charge recombination, which leads to a significant enhancement of the power conversion efficiency from 6.47% to 8.34% for Poly({4,8-bis[(2-ethylhexyloxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexylcarbonyl]thieno[3,4-b]thiophenediyl} (PTB7:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM-based OSCs. In addition, the long-term stability of the OSC is improved by using the ITR-GO/PFN CIL when compared with the pristine device. These results indicate that the bilayer ITR-GO/PFN CIL is a promising way to realize high-efficiency and stable OSCs by using water-soluble conjugated polymer electrolytes such as PFN.

  10. Electron Microscopy of Nanostructures in Cells

    DEFF Research Database (Denmark)

    Købler, Carsten

    with cells is therefore increasingly more relevant from both an engineering and a toxicological viewpoint. My work involves developing and exploring electron microscopy (EM) for imaging nanostructures in cells, for the purpose of understanding nanostructure-cell interactions in terms of their possibilities...

  11. Structurally controlled deposition of silicon onto nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weijie; Liu, Zuqin; Han, Song; Bornstein, Jonathan; Stefan, Constantin Ionel

    2018-03-20

    Provided herein are nanostructures for lithium ion battery electrodes and methods of fabrication. In some embodiments, a nanostructure template coated with a silicon coating is provided. The silicon coating may include a non-conformal, more porous layer and a conformal, denser layer on the non-conformal, more porous layer. In some embodiments, two different deposition processes, e.g., a PECVD layer to deposit the non-conformal layer and a thermal CVD process to deposit the conformal layer, are used. Anodes including the nanostructures have longer cycle lifetimes than anodes made using either a PECVD or thermal CVD method alone.

  12. Work Function Adjustment by Using Dipole Engineering for TaN-Al2O3-Si3N4-HfSiOx-Silicon Nonvolatile Memory

    Directory of Open Access Journals (Sweden)

    Yu-Hsien Lin

    2015-08-01

    Full Text Available This paper presents a novel TaN-Al2O3-HfSiOx-SiO2-silicon (TAHOS nonvolatile memory (NVM design with dipole engineering at the HfSiOx/SiO2 interface. The threshold voltage shift achieved by using dipole engineering could enable work function adjustment for NVM devices. The dipole layer at the tunnel oxide–charge storage layer interface increases the programming speed and provides satisfactory retention. This NVM device has a high program/erase (P/E speed; a 2-V memory window can be achieved by applying 16 V for 10 μs. Regarding high-temperature retention characteristics, 62% of the initial memory window was maintained after 103 P/E-cycle stress in a 10-year simulation. This paper discusses the performance improvement enabled by using dipole layer engineering in the TAHOS NVM.

  13. Special Issue: The Silicon Age

    Science.gov (United States)

    Kittler, Martin; Yang, Deren

    2006-03-01

    The present issue of physica status solidi (a) contains a collection of articles about different aspects of current silicon research and applications, ranging from basic investigations of mono- and polycrystalline silicon materials and nanostructures to technologies for device fabrication in silicon photovoltaics, micro- and optoelectronics. Guest Editors are Martin Kittler and Deren Yang, the organizers of a recent Sino-German symposium held in Cottbus, Germany, 19-24 September 2005.The cover picture shows four examples of The Silicon Age: the structure of a thin film solar cell on low-cost SSP (silicon sheet from powder) substrate (upper left image) [1], a high-resolution transmission electron microscopy image and diffraction pattern of a single-crystalline Si nanowire (upper right) [2], a carrier lifetime map from an n-type multicrystalline silicon wafer after gettering by a grain boundary (lower left) [3], and a scanning acoustic microscopy image of a bonded 150 mm diameter wafer pair (upper right) [4].

  14. A new lithium-ion battery using 3D-array nanostructured graphene-sulfur cathode and silicon oxide-based anode.

    Science.gov (United States)

    Benítez, Almudena; Di Lecce, Daniele; Elia, Giuseppe Antonio; Caballero, Álvaro; Morales, Julián; Hassoun, Jusef

    2018-02-28

    In this work we report an efficient lithium-ion battery using enhanced sulfur-based cathode and silicon oxide-based anode as novel energy-storage system. The sulfur-carbon composite, exploiting graphene carbon with 3D array (3DG-S), is synthesized by reduction step and microwave-assisted solvothermal technique and fully characterized in terms of structure, morphology, thereby revealing suitable features for lithium-cell application. Electrochemical tests indicate the 3DG-S electrode as very stable and performing cathode in lithium half-cell, with capacity ranging from 1200 to 1000 mAh g-1 at C/10 and 1C rates, respectively. Remarkably, the Li-alloying anode, namely a LiySiOx-C prepared by the sol-gel method and lithiated by surface treatment, shows a suitable performance in lithium half-cell using an electrolyte designed for lithium-sulfur battery. The LiySiOx-C/3DG-S battery reveals very promising results with a capacity of about 460 mAh gS-1 delivered at average voltage of about 1.5 V over 200 cycles, suggesting the characterized materials as suitable candidates for low-cost and high-energy storage application. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Characterization of Urea Versus hmta in the Preparation of Zinc Oxide NANOSTRUCTURES by Catalytic Immersion Method Grown on Gold-seeded Silicon Substrate

    International Nuclear Information System (INIS)

    Azlinda Abdul Aziz; Khusaimi, Z.; Rusop, M.

    2011-01-01

    Zinc oxide (ZnO) nano structured prepared by immersed method were successfully grown on gold-seeded silicon substrate using Zinc nitrate hexahydrate (Zn(NO 3 ) 2 .6H 2 O) as a precursor was stabilized by a non-toxic urea (CH 4 N 2 O) in a ratio of 1:2 and 1:1 ratio of hexamethylene tetraamine (HMTA). The effect of changing the stabilizer of ZnO solution on the crystal structure, morphology and photoluminescence properties of the resultant ZnO is investigated. X-ray diffraction of the synthesized ZnO shows hexagonal zincite structure. The morphology of the ZnO was characterizing using Field Emission Scanning Electron Microscope (FESEM). The growth of ZnO using urea as stabilizer shows the clusters of ZnO nano flower with serrated broad petals and sharp tips of approximately 25 nm were interestingly formed. ZnO in HMTA showed growth of nano rods. The structures has high surface area, is a potential metal oxide nano structures to be develop for optoelectronic devices and chemical sensors. The formation of ZnO nano structures is found to be significantly affected by the stabilizer. (author)

  16. Highly tunable electronic properties in plasma-synthesized B-doped microcrystalline-to-amorphous silicon nanostructure for solar cell applications

    Science.gov (United States)

    Lim, J. W. M.; Ong, J. G. D.; Guo, Y.; Bazaka, K.; Levchenko, I.; Xu, S.

    2017-10-01

    Highly controllable electronic properties (carrier mobility and conductivity) were obtained in the sophisticatedly devised, structure-controlled, boron-doped microcrystalline silicon structure. Variation of plasma parameters enabled fabrication of films with the structure ranging from a highly crystalline (89.8%) to semi-amorphous (45.4%) phase. Application of the innovative process based on custom-designed, optimized, remote inductively coupled plasma implied all advantages of the plasma-driven technique and simultaneously avoided plasma-intrinsic disadvantages associated with ion bombardment and overheating. The high degree of SiH4, H2 and B2H6 precursor dissociation ensured very high boron incorporation into the structure, thus causing intense carrier scattering. Moreover, the microcrystalline-to-amorphous phase transition triggered by the heavy incorporation of the boron dopant with increasing B2H6 flow was revealed, thus demonstrating a very high level of the structural control intrinsic to the process. Control over the electronic properties through variation of impurity incorporation enabled tailoring the carrier concentrations over two orders of magnitude (1018-1020 cm-3). These results could contribute to boosting the properties of solar cells by paving the way to a cheap and efficient industry-oriented technique, guaranteeing a new application niche for this new generation of nanomaterials.

  17. Friction-induced nanofabrication on monocrystalline silicon

    International Nuclear Information System (INIS)

    Yu Bingjun; Qian Linmao; Yu Jiaxin; Zhou Zhongrong; Dong Hanshan; Chen Yunfei

    2009-01-01

    Fabrication of nanostructures has become a major concern as the scaling of device dimensions continues. In this paper, a friction-induced nanofabrication method is proposed to fabricate protrusive nanostructures on silicon. Without applying any voltage, the nanofabrication is completed by sliding an AFM diamond tip on a sample surface under a given normal load. Nanostructured patterns, such as linear nanostructures, nanodots or nanowords, can be fabricated on the target surface. The height of these nanostructures increases rapidly at first and then levels off with the increasing normal load or number of scratching cycles. TEM analyses suggest that the friction-induced hillock is composed of silicon oxide, amorphous silicon and deformed silicon structures. Compared to the tribochemical reaction, the amorphization and crystal defects induced by the mechanical interaction may have played a dominating role in the formation of the hillocks. Similar to other proximal probe methods, the proposed method enables fabrication at specified locations and facilitates measuring the dimensions of nanostructures with high precision. It is highlighted that the fabrication can also be realized on electrical insulators or oxide surfaces, such as quartz and glass. Therefore, the friction-induced method points out a new route in fabricating nanostructures on demand.

  18. Doped nanocrystalline silicon oxide for use as (intermediate) reflecting layers in thin-film silicon solar cells

    NARCIS (Netherlands)

    Babal, P.

    2014-01-01

    In summary, this thesis shows the development and nanostructure analysis of doped silicon oxide layers. These layers are applied in thin-film silicon single and double junction solar cells. Concepts of intermediate reflectors (IR), consisting of silicon and/or zinc oxide, are applied in tandem

  19. Synthesis and properties of ferromagnetic nanostructures embedded within a high-quality crystalline silicon matrix via ion implantation and nanocavity assisted gettering processes

    Energy Technology Data Exchange (ETDEWEB)

    Malladi, Girish; Huang, Mengbing, E-mail: mhuang@albany.edu; Murray, Thomas; Novak, Steven; Matsubayashi, Akitomo; LaBella, Vincent; Bakhru, Hassaram [SUNY College of Nanoscale Science and Engineering, Albany, New York 12203 (United States)

    2014-08-07

    Integrating magnetic functionalities with silicon holds the promise of developing, in the most dominant semiconductor, a paradigm-shift information technology based on the manipulation and control of electron spin and charge. Here, we demonstrate an ion implantation approach enabling the synthesis of a ferromagnetic layer within a defect free Si environment by exploiting an additional implant of hydrogen in a region deep below the metal implanted layer. Upon post-implantation annealing, nanocavities created within the H-implanted region act as trapping sites for gettering the implanted metal species, resulting in the formation of metal nanoparticles in a Si region of excellent crystal quality. This is exemplified by the synthesis of magnetic nickel nanoparticles in Si implanted with H{sup +} (range: ∼850 nm; dose: 1.5 × 10{sup 16 }cm{sup −2}) and Ni{sup +} (range: ∼60 nm; dose: 2 × 10{sup 15 }cm{sup −2}). Following annealing, the H implanted regions populated with Ni nanoparticles of size (∼10–25 nm) and density (∼10{sup 11}/cm{sup 2}) typical of those achievable via conventional thin film deposition and growth techniques. In particular, a maximum amount of gettered Ni atoms occurs after annealing at 900 °C, yielding strong ferromagnetism persisting even at room temperature, as well as fully recovered crystalline Si environments adjacent to these Ni nanoparticles. Furthermore, Ni nanoparticles capsulated within a high-quality crystalline Si layer exhibit a very high magnetic switching energy barrier of ∼0.86 eV, an increase by about one order of magnitude as compared to their counterparts on a Si surface or in a highly defective Si environment.

  20. Polymer Masks for nanostructuring of graphene

    DEFF Research Database (Denmark)

    Shvets, Violetta

    This PhD project is a part of Center for Nanostructured Graphene (CNG) activities. The aim of the project is to develop a new lithography method for creation of highly ordered nanostructures with as small as possible feature and period sizes. The method should be applicable for graphene...... polymer masks is developed. Mask fabrication is realized by microtoming of 30-60 nm thin sections from pre-aligned polymer monoliths with different morphologies. The resulting polymer masks are then transferred to both silicon and graphene substrates. Hexagonally packed hole patterns with 10 nm hole...... diameter and 20 nm periodicity are successfully transferred to both substrates. The method allowed to realize the first ever transfer of moiré patterns to silicon. Furthermore, in collaboration with CNG, device with nanostructured graphene are fabricated and electrical measurements made on these devices...

  1. PREFACE: 2nd International School and Conference Saint-Petersburg OPEN on Optoelectronics, Photonics, Engineering and Nanostructures (SPbOPEN2015)

    Science.gov (United States)

    2015-11-01

    The 2nd International School and Conference ''Saint Petersburg OPEN 2015'' on Optoelectronics, Photonics, Engineering and Nanostructures was held on April 6 - 8, 2015 at St. Petersburg Academic University. The School and Conference included a series of invited talks given by leading professors with the aim to introduce young scientists with actual problems and major advances in physics and technology. The keynote speakers were Mikhail V. Maximov (Ioffe Physico-Technical Institute RAS, Russia) Vladimir G. Dubrovskii (St. Petersburg Academic University and St. Petersburg State University, Russia) Anton Yu. Egorov (JSC Connector Optics, Russia) Victor V. Luchinin (St. Petersburg State Electrotechnical University, Russia) Vladislav E. Bugrov (St. Petersburg University of Internet Technologies, Mechanics and Optics, Russia) Vitali A. Schukin (VI Systems, Germany) Yuri P. Svirko (University of Eastern Finland, Finland) During the poster session all undergraduate and graduate students attending the conference presented their works. A sufficiently large number of participants, with more than 170 student attendees from all over the world, allowed the Conference to provide a fertile ground for fruitful discussions between the young scientists as well as to become a perfect platform for valuable discussions between student authors and highly experienced scientists. The best student papers, which were selected by the Program Committee and by the invited speakers basing on the theses and their poster presentation, were awarded with diplomas of the conference - see the photos. This year ''Saint Petersburg OPEN 2015'' is organized by St. Petersburg Academic University in cooperation with Peter the Great St. Petersburg Polytechnic University. The School and Conference is supported by Russian Science Foundation, SPIE (The International Society for Optics and Photonics), OSA (The Optical Society) and by Skolkovo Foundation. It is a continuation of the annual schools and seminars for

  2. Grain boundary engineering of La{sub 0.7} Sr{sub 0.3} MnO{sub 3} films on silicon substrate: Scanning Tunneling Microscopy-Spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Anupama [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India); Nori, Rajashree [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology (IIT Bombay), Mumbai 400076 (India); Dhobale, Sandip [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India); Ramgopal Rao, V. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology (IIT Bombay), Mumbai 400076 (India); Kale, S.N., E-mail: sangeetakale2004@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India); Datar, Suwarna, E-mail: suwarna.datar@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India)

    2014-09-01

    We employed a Scanning Tunnelling Microscope (STM) to study the surface topography and spatially resolved local electronic properties like local density of states (LDOS) of nanostructured films of La{sub 0.7} Sr{sub 0.3} MnO{sub 3} (LSMO). The nanostructured thin films of LSMO on silicon substrate were prepared using Pulsed Laser Deposition (PLD) technique. The deposition conditions were tuned to yield two different morphologies; one with uniform columnar closely packed islands and other with larger grain distribution in random fashion. The Scanning Tunnelling Spectroscopy (STS) revealed the extent of variation of density of states (DOS) near the Fermi level. From the spectroscopic features obtained we found the occurrence of phase separation between conducting and semiconducting domains and its possible correlation with the properties of the system. Semiconducting nature was observed at the grain boundaries, which could be extremely promising in futuristic nano-devices.

  3. Investigating the Potential Barrier Function of Nanostructured Materials Formed in Engineered Barrier Systems (EBS) Designed for Nuclear Waste Isolation.

    Science.gov (United States)

    Cuevas, Jaime; Ruiz, Ana Isabel; Fernández, Raúl

    2018-02-21

    Clay and cement are known nano-colloids originating from natural processes or traditional materials technology. Currently, they are used together as part of the engineered barrier system (EBS) to isolate high-level nuclear waste (HLW) metallic containers in deep geological repositories (DGR). The EBS should prevent radionuclide (RN) migration into the biosphere until the canisters fail, which is not expected for approximately 10 3  years. The interactions of cementitious materials with bentonite swelling clay have been the scope of our research team at the Autonomous University of Madrid (UAM) with participation in several European Union (EU) projects from 1998 up to now. Here, we describe the mineral and chemical nature and microstructure of the alteration rim generated by the contact between concrete and bentonite. Its ability to buffer the surrounding chemical environment may have potential for further protection against RN migration. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Steps towards silicon optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Starovoytov, A

    1999-07-01

    This thesis addresses the issue of a potential future microelectronics technology, namely the possibility of utilising the optical properties of nanocrystalline silicon for optoelectronic circuits. The subject is subdivided into three chapters. Chapter 1 is an introduction. It formulates the oncoming problem for microelectronic development, explains the basics of Integrated Optoelectronics, introduces porous silicon as a new light-emitting material and gives a brief review of other competing light-emitting material systems currently under investigation. Examples of existing porous silicon devices are given. Chapter 2 reviews the basic physics relevant to the subject of this thesis and in-forms on the present situation in this field of research, including both experimental and theoretical knowledge gained up-to-date. The chapter provides the necessary background for correct interpretation of the results reported in Chapter 3 and for a realistic decision on the direction for future work. Chapter 3 describes my own experimental and computational results within the framework of the subject, obtained at De Montfort University. These include: one-step preparation of laterally structured porous silicon with photoluminescence and microscopy characterisation, Raman spectroscopy of porous silicon, a polarisation study of the photoluminescence from porous silicon, computer simulations of the conductivity of two-component media and of laser focused atomic deposition for nanostructure fabrication. Thus, this thesis makes a dual contribution to the chosen field: it summarises the present knowledge on the possibility of utilising optical properties of nanocrystalline silicon in silicon-based electronics, and it reports new results within the framework of the subject. The main conclusion is that due to its promising optoelectronic properties nanocrystalline silicon remains a prospective competitor for the cheapest and fastest microelectronics of the next century. (author)

  5. Resonant tunnelling from nanometre-scale silicon field emission cathodes

    International Nuclear Information System (INIS)

    Johnson, S.; Markwitz, A.

    2005-01-01

    In this paper we report the field emission properties of self-assembled silicon nanostructures formed on an n-type silicon (100) substrate by electron beam annealing. The nanostructures are square based, with an average height of 8 nm and are distributed randomly over the entire substrate surface. Following conditioning, the silicon nanostructure field emission characteristics become stable and reproducible with electron emission occurring for fields as low as 3 Vμm-1. At higher fields, a superimposed on a background current well described by conventional Fowler-Nordheim theory. These current peaks are understood to result from enhanced tunnelling through resonant states formed at the substrate-nanostructure and nanostructure-vacuum interface. (author). 13 refs., 3 figs

  6. Silicone metalization

    Energy Technology Data Exchange (ETDEWEB)

    Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  7. Advances in silicon nanophotonics

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Pu, Minhao

    plasma effect have been tested up to 40 Gbit/s, and hybrid evanescent silicon lasers have been realized both in the form of distributed feed-back lasers and micro-disk lasers. For enhancing the impact of silicon photonics in future ultrafast and energy-efficient all-optical signal processing, e.......g. in high-bit-rate optical communication circuits and networks, it is vital that the nonlinear optical effects of silicon are being strongly enhanced. This can among others be achieved in photonic-crystal slow-light waveguides and in nano-engineered photonic-wires (Fig. 1). In this talk I shall present some......Silicon has long been established as an ideal material for passive integrated optical circuitry due to its high refractive index, with corresponding strong optical confinement ability, and its low-cost CMOS-compatible manufacturability. However, the inversion symmetry of the silicon crystal lattice...

  8. Biological insertion of nanostructured germanium and titanium oxides into diatom biosilica

    Science.gov (United States)

    Jeffryes, Clayton S.

    There is significant interest in titanium oxide and germanium-silicon oxide nanocomposites for optoelectronic, photocatalytic, and solar cell applications. The ability of the marine diatom Pinnularia sp. to uptake soluble metal oxides from cell culture medium, and incorporate them into the micro- and nano-structure of their amorphous silica cell walls, called frustules, was evaluated using an engineered photobioreactor system. The effects of metal oxides on the structural and elemental properties of the frustule were also evaluated. Diatom cell cultures grown in 5 L photobioreactors were initially charged with 0.5 mM of soluble silicon, Si(OH)4, an obligate substrate required for frustule fomation. Upon exhaustion of Si(OH)4 cells were exposed to the mixed pulse-addition of soluble silicon and germanium or co-perfusion addition of soluble silicon and titanium, which were incorporated into the frustules. Metals composition of the cell culture medium, diatom biomass and purified frustules were measured, as was the local elemental composition within the frustule pores and the metal oxide crystallinity. Diatom frustules having a germanium composition of 1.6 wt % were devoid of the native intra-pore structures and possessed enhanced photoluminescence and electroluminescence when compared to frustules without Ge. Diatoms cultivated in the presence of soluble titanium incorporated amorphous titania into the frustule, which maintained native structure even when local TiO2 concentrations within the nanopores approached 60 wt. %. Titanium oxide could also be biomimetically deposited directly within the diatom nanopores by adsorbing poly-L-lysine to the diatom biosilica where it catalyzed the soluble titanium precursor Ti-BALDH into amorphous titania nanoparticles. Both biogenic and biomimetic titania could be converted to anatase titanium by thermal annealing. It was determined that nanostructured metal oxide composites can be fabricated biomimetically or in cell culture to

  9. Phosphorous Doping of Nanostructured Crystalline Silicon

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Steckel, André

    surface aspect ration (22.25) of bSi to planar surface doping concentration might be slightly higher than on planar surfaces. Therefore, we conducted a study and present recent results of doping of bSi and compared their properties to planar Si. We doped planar, KOH-etched random pyramid and bSi surfaces...... with phosphorous (POCl3) in the temperature range 850-1000oC for 15 and 20 min, respectively. Sheet resistance measurements show slight differences in doping density between planar, KOH pyramidal and bSi structures. bSi samples have lower sheet resistance, pointing to higher doping density presumably due...

  10. Fabrication of Nanostructures Using Self-Assembled Peptides as Templates

    DEFF Research Database (Denmark)

    Castillo, Jaime

    2015-01-01

    This chapter evaluates the use of a short-aromatic dipeptide, diphenylalanine, as a template in the fabrication of new nanostructures (nanowires, coaxial nanocables, nanochannels) using materials such as silicon, conducting and non-conducting polymers. Diphenylalanine self-organize into nanostruc......This chapter evaluates the use of a short-aromatic dipeptide, diphenylalanine, as a template in the fabrication of new nanostructures (nanowires, coaxial nanocables, nanochannels) using materials such as silicon, conducting and non-conducting polymers. Diphenylalanine self......-organize into nanostructures (nanotubes, nanofibers or nanospheres) under very mild conditions; some of its properties make them excellent candidates to be use as, for instance, dry-etch masks in a reactive ion etching process for the rapid fabrication of silicon micro and nanowires. Here, the methods used to exploit...

  11. Enhanced extraction of silicon-vacancy centers light emission using bottom-up engineered polycrystalline diamond photonic crystal slabs

    Czech Academy of Sciences Publication Activity Database

    Ondič, Lukáš; Varga, Marián; Hruška, Karel; Fait, J.; Kapusta, Peter

    2017-01-01

    Roč. 11, č. 3 (2017), s. 2972-2981 ISSN 1936-0851 R&D Projects: GA ČR GJ16-09692Y; GA MŠk LD15003; GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : photonic crystal * diamond * silicon vacancy center Subject RIV: BM - Solid Matter Physics ; Magnetism; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Physical chemistry (UFCH-W) Impact factor: 13.942, year: 2016

  12. Time-resolved terahertz spectroscopy of semiconductor nanostructures

    DEFF Research Database (Denmark)

    Porte, Henrik

    This thesis describes time-resolved terahertz spectroscopy measurements on various semiconductor nanostructures. The aim is to study the carrier dynamics in these nanostructures on a picosecond timescale. In a typical experiment carriers are excited with a visible or near-infrared pulse...... be signicantly reduced. Besides time-resolved terahertz spectroscopy measurement, optical transmission, Raman spectroscopy, scanning electron microscope, energy dispersive X-ray, and X-ray diffraction spectroscopy experiments on black silicon are presented....

  13. Nanostructured catalysts for organic transformations.

    Science.gov (United States)

    Chng, Leng Leng; Erathodiyil, Nandanan; Ying, Jackie Y

    2013-08-20

    and/or recyclability of the nanostructured catalysts via control of the structure, composition of the catalytically active NPs, and/or nature of the support. These principles will aid researchers in the rational design and engineering of new types of multifunctional nanocatalysts for the achievement of green and sustainable chemical processes. Although the past decade has brought many advances, there are still challenges in the area of nanocatalysis that need to be addressed. These include loss of catalytic activity during operation due to sintering, leaching of soluble species from the nanocatalysts under harsh reaction conditions, loss of control over well-defined morphologies during the scale-up synthesis of the nanocomposites, and limited examples of enantioselective nanocatalytic systems. The future of nanocatalyst research lies in the judicious design and development of nanocomposite catalysts that are stable and resistant to sintering and leaching, and yet are highly active and enantioselective for the desired catalytic organic transformations, even after multiple runs. The successful generation of such multifunctional nanocatalysts especially in tandem, domino, or cascade reactions would provide a powerful tool for the establishment of green and sustainable technologies.

  14. Thermal resistance between low-dimensional nanostructures and semi-infinite media

    Science.gov (United States)

    Panzer, Matthew A.; Goodson, Ken E.

    2008-05-01

    Nanostructured electronic and photonic devices include a high density of material interfaces, which can strongly impede heat conduction and influence performance and reliability. Thermal conduction through interfaces is a very mature discipline for the traditional geometry, in which the lateral interface dimensions are large compared to the phonon wavelength. In nanostructures, however, the localization of phonons in the directions parallel to the interface may strongly influence the effective thermal resistance. The present work investigates model problems of abrupt junctions between a harmonic one-dimensional (1D) and a three-dimensional (3D) fcc lattice and between a 1D and a two-dimensional square lattice. The abrupt change in geometry modifies the phonon modes participating in energy transmission and creates an additional thermal resistance that is comparable with that occurring due to the acoustic mismatch at the interface of bulk media. For both cases, varying the impedance mismatch at the junction suggests that engineering an intentional impedance mismatch at a nanostructured interface may enhance the transmission of energy. The lattice dynamics calculations are used to develop qualitative arguments for the interface resistances in the practical geometries involving carbon nanotubes, silicon nanopillars, and graphene. This research provides foundations for detailed investigations of the impact of localized phonon modes on the acoustic mismatch resistance.

  15. Passivation of surface-nanostructured f-SiC and porous SiC

    DEFF Research Database (Denmark)

    Ou, Haiyan; Lu, Weifang; Ou, Yiyu

    The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper.......The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper....

  16. Semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Marstein Erik Stensrud

    2003-07-01

    This thesis presents a study of two material systems containing semiconductor nanocrystals, namely porous silicon (PSi) films and germanium (Ge) nanocrystals embedded in silicon dioxide (SiO2) films. The PSi films were made by anodic etching of silicon (Si) substrates in an electrolyte containing hydrofluoric acid. The PSi films were doped with erbium (Er) using two different doping methods. electrochemical doping and doping by immersing the PSi films in a solution containing Er. The resulting Er concentration profiles were investigated using scanning electron microscopy (SEN1) combined with energy dispersive X-ray analysis (EDS). The main subject of the work on PSi presented in this thesis was investigating and comparing these two doping methods. Ge nanocrystals were made by implanting Ge ions into Si02 films that were subsequently annealed. However. nanocrystal formation occurred only for certain sets of processing parameters. The dependence of the microstructure of the Ge implanted Si02 films on the processing parameters were therefore investigated. A range of methods were employed for these investigations, including transmission electron microscopy (TEM) combined with EDS, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The observed structures, ranging from Ge nanocrystals to voids with diameters of several tens of nanometers and Ge rich Si02 films without any nanocrystals is described. A model explaining the void formation is also presented. For certain sets of processing parameters. An accumulation of Ge at the Si-Si02 interface was observed. The effect of this accumulation on the electrical properties of MOS structures made from Ge implanted SiO2 films was investigated using CV-measurements. (Author)

  17. Micro-‘‘factory’’ for self-assembled peptide nanostructures

    DEFF Research Database (Denmark)

    Castillo, Jaime; Rodriguez-Trujíllo, Romén; Gauthier, Sébastian

    2011-01-01

    nanostructures due to the mild conditions of their synthesis process. This biological material can form nanostructures in a rapid way and the synthesis method is less expensive as compared to that of carbon nanotubes or silicon nanowires. The present article thus reports on the on-chip fabrication of self...

  18. Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

    International Nuclear Information System (INIS)

    Li, Ming; Kang, Zhan; Huang, Xiaobo

    2015-01-01

    Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-network (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials

  19. Magnetism in carbon nanostructures

    CERN Document Server

    Hagelberg, Frank

    2017-01-01

    Magnetism in carbon nanostructures is a rapidly expanding field of current materials science. Its progress is driven by the wide range of applications for magnetic carbon nanosystems, including transmission elements in spintronics, building blocks of cutting-edge nanobiotechnology, and qubits in quantum computing. These systems also provide novel paradigms for basic phenomena of quantum physics, and are thus of great interest for fundamental research. This comprehensive survey emphasizes both the fundamental nature of the field, and its groundbreaking nanotechnological applications, providing a one-stop reference for both the principles and the practice of this emerging area. With equal relevance to physics, chemistry, engineering and materials science, senior undergraduate and graduate students in any of these subjects, as well as all those interested in novel nanomaterials, will gain an in-depth understanding of the field from this concise and self-contained volume.

  20. A MEMS Infrared Thermopile Fabricated from Silicon-On-Insulator with Phononic Crystal Structures and Carbon Nanotube Absorption Layer

    Science.gov (United States)

    Gray, Kory Forrest

    The goal of this project was to examine the possibility of creating a novel thermal infrared detector based on silicon CMOS technology that has been enhanced by the latest nano-engineering discoveries. Silicon typically is not thought as an efficient thermoelectric material. However recent advancements in nanotechnology have improved the potential for a highly sensitive infrared detector based on nano-structured silicon. The thermal conductivity of silicon has been shown to be reduced from 150 W/mK down to 60 W/mK just by decreasing the scale of the silicon from bulk down to the sub-micron scale. Further reduction of the thermal conductivity has been shown by patterning silicon with a phonon crystal structure which has been reported to have thermal conductivities down to 10 W/mK. The phonon crystal structure consists of a 2D array of holes that are etched into the silicon. The size and pitch of the holes are on the order of the mean free path of the phonons in silicon which is approximately 200-500nm. This particular device had 200nm holes on a 400nm pitch. The Seebeck coefficient of silicon can also be enhanced by the reduction of the material from the bulk to sub-micron scale and with degenerate level doping. The combination of decreased thermal conductivity and increased Seebeck coefficient allow silicon to be a promising material for thermoelectric infrared detectors. The highly doped silicon is desired to reduce the electrical resistance of the device. The low electrical resistance is required to reduce the Johnson noise of the device which is the dominant noise source for most thermal detectors. This project designed a MEMS thermopile using a silicon-on-insulator substrate, and a CMOS compatible process. The basic thermopile consists of a silicon dioxide membrane with phononic crystal patterned silicon thermocouples around the edges of the membrane. Vertical aligned, multi-walled, carbon nanotubes were used as the infrared absorption layer. A MEMS

  1. Enhanced Extraction of Silicon-Vacancy Centers Light Emission Using Bottom-Up Engineered Polycrystalline Diamond Photonic Crystal Slabs.

    Science.gov (United States)

    Ondič, Lukáš; Varga, Marian; Hruška, Karel; Fait, Jan; Kapusta, Peter

    2017-03-28

    Silicon vacancy (SiV) centers are optically active defects in diamond. The SiV centers, in contrast to nitrogen vacancy (NV) centers, possess narrow and efficient luminescence spectrum (centered at ≈738 nm) even at room temperature, which can be utilized for quantum photonics and sensing applications. However, most of light generated in diamond is trapped in the material due to the phenomenon of total internal reflection. In order to overcome this issue, we have prepared two-dimensional photonic crystal slabs from polycrystalline diamond thin layers with high density of SiV centers employing bottom-up growth on quartz templates. We have shown that the spectral overlap between the narrow light emission of the SiV centers and the leaky modes extracting the emission into almost vertical direction (where it can be easily detected) can be obtained by controlling the deposition time. More than 14-fold extraction enhancement of the SiV centers photoluminescence was achieved compared to an uncorrugated sample. Computer simulation confirmed that the extraction enhancement originates from the efficient light-matter interaction between light emitted from the SiV centers and the photonic crystal slab.

  2. Optical properties of nano-silicon

    Indian Academy of Sciences (India)

    Unknown

    light-emitting films have been made applying various tech- niques such as sputtering, plasma processing and anodic etching. Morisaki et al (1991) reported the visible light luminescence from some other form of Si nanostructures such as Si ultrafine particles deposited by evaporation of silicon powders in an Ar atmosphere.

  3. Characterization of ion beam induced nanostructures

    International Nuclear Information System (INIS)

    Ghatak, J.; Satpati, B.; Umananda, M.; Kabiraj, D.; Som, T.; Dev, B.N.; Akimoto, K.; Ito, K.; Emoto, T.; Satyam, P.V.

    2006-01-01

    Tailoring of nanostructures with energetic ion beams has become an active area of research leading to the fundamental understanding of ion-solid interactions at nanoscale regime and with possible applications in the near future. Rutherford backscattering spectrometry (RBS), high resolution transmission electron microscopy (HRTEM) and asymmetric X-ray Bragg-rocking curve experimental methods have been used to characterize ion-induced effects in nanostructures. The possibility of surface and sub-surface/interface alloying at nano-scale regime, ion-beam induced embedding, crater formation, sputtering yield variations for systems with isolated nanoislands, semi-continuous and continuous films of noble metals (Au, Ag) deposited on single crystalline silicon will be reviewed. MeV-ion induced changes in specified Au-nanoislands on silicon substrate are tracked as a function of ion fluence using ex situ TEM. Strain induced in the bulk silicon substrate surface due to 1.5 MeV Au 2+ and C 2+ ion beam irradiation is determined by using HRTEM and asymmetric Bragg X-ray rocking curve methods. Preliminary results on 1.5 MeV Au 2+ ion-induced effects in nanoislands of Co deposited on silicon substrate will be discussed

  4. Characterization of ion beam induced nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ghatak, J. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Satpati, B. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Umananda, M. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Kabiraj, D. [Nuclear Science Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Som, T. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Dev, B.N. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Akimoto, K. [Department of Quantum Engineering, Nagoya University, Nagoya 464-8603 (Japan); Ito, K. [Department of Quantum Engineering, Nagoya University, Nagoya 464-8603 (Japan); Emoto, T. [Toyota National College of Technology, 2-1, Toyota, Aichi 471-8525 (Japan); Satyam, P.V. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)]. E-mail: satyam@iopb.res.in

    2006-03-15

    Tailoring of nanostructures with energetic ion beams has become an active area of research leading to the fundamental understanding of ion-solid interactions at nanoscale regime and with possible applications in the near future. Rutherford backscattering spectrometry (RBS), high resolution transmission electron microscopy (HRTEM) and asymmetric X-ray Bragg-rocking curve experimental methods have been used to characterize ion-induced effects in nanostructures. The possibility of surface and sub-surface/interface alloying at nano-scale regime, ion-beam induced embedding, crater formation, sputtering yield variations for systems with isolated nanoislands, semi-continuous and continuous films of noble metals (Au, Ag) deposited on single crystalline silicon will be reviewed. MeV-ion induced changes in specified Au-nanoislands on silicon substrate are tracked as a function of ion fluence using ex situ TEM. Strain induced in the bulk silicon substrate surface due to 1.5 MeV Au{sup 2+} and C{sup 2+} ion beam irradiation is determined by using HRTEM and asymmetric Bragg X-ray rocking curve methods. Preliminary results on 1.5 MeV Au{sup 2+} ion-induced effects in nanoislands of Co deposited on silicon substrate will be discussed.

  5. Periodic nanostructures on unpolished substrates and their integration in solar cells

    Science.gov (United States)

    Cornago, I.; Dominguez, S.; Ezquer, M.; Rodríguez, M. J.; Lagunas, A. R.; Pérez-Conde, J.; Rodriguez, R.; Bravo, J.

    2015-03-01

    We present a novel fabrication process based on laser interference lithography, lift-off and reactive ion etching, which allows us to fabricate periodic nanostructures on photovoltaic substrates with an average root mean square (RMS) roughness of 750 nm. We fabricate nanostructures on unpolished crystalline silicon substrates, which reduces their reflectance 30% as fabricated. When an additional passivation layer is deposited, the light trapping grows, achieving a reflectance reduction of 60%. In addition, we have successfully integrated the nanostructured substrates in silicon wafer-based solar cells following standard processes, achieving a final efficiency of 15.56%.

  6. Semiconducting silicon nanowires for biomedical applications

    CERN Document Server

    Coffer, JL

    2014-01-01

    Biomedical applications have benefited greatly from the increasing interest and research into semiconducting silicon nanowires. Semiconducting Silicon Nanowires for Biomedical Applications reviews the fabrication, properties, and applications of this emerging material. The book begins by reviewing the basics, as well as the growth, characterization, biocompatibility, and surface modification, of semiconducting silicon nanowires. It goes on to focus on silicon nanowires for tissue engineering and delivery applications, including cellular binding and internalization, orthopedic tissue scaffol

  7. Self-aligned mask renewal for anisotropically etched circular micro- and nanostructures

    International Nuclear Information System (INIS)

    Kaspar, Peter; Jäckel, Heinz; Holzapfel, Sebastian; Windhab, Erich J

    2011-01-01

    The top–down fabrication of high aspect ratio circular micro- and nanostructures in silicon nitride is presented. A new method is introduced to increase the aspect ratio of anisotropically etched holes by a factor of more than two with respect to the results obtained from an established dry-etching process. The method is based on the renewal of an etching mask after a first etching step has been completed. Mask renewal is done by line-of-sight deposition of a masking layer on the surface of the sample, which is mounted at an angle with respect to the deposition direction. No additional alignment step is required. The proof of principle is performed for silicon nitride etching through a mask of titanium, but the method has great potential to be applicable to a wide variety of substrate–mask combinations and to find entrance into various engineering fields. Two specific applications are highlighted. Firstly, a thick silicon nitride hardmask is used for the fabrication of deeply etched photonic crystal holes in indium phosphide (InP). For holes of 280 nm diameter, a record aspect ratio of 20 and an overall selectivity of 28.5 between a positive-tone resist layer and InP are reported. Secondly, the use of perforated silicon nitride membranes for droplet formation for applications in food engineering or pharmaceutics is addressed. Preliminary results show a potential for the self-aligned mask renewal method to exceed state-of-the-art membrane quality in terms of pore size, aspect ratio and membrane stability.

  8. Nanostructured Biomaterials and Their Applications

    Directory of Open Access Journals (Sweden)

    Kirsten Parratt

    2013-05-01

    Full Text Available Some of the most important advances in the life sciences have come from transitioning to thinking of materials and their properties on the nanoscale rather than the macro or even microscale. Improvements in imaging technology have allowed us to see nanofeatures that directly impact chemical and mechanical properties of natural and man-made materials. Now that these can be imaged and quantified, substantial advances have been made in the fields of biomimetics, tissue engineering, and drug delivery. For the first time, scientists can determine the importance of nanograins and nanoasperities in nacre, direct the nucleation of apatite and the growth of cells on nanostructured scaffolds, and pass drugs tethered to nanoparticles through the blood-brain barrier. This review examines some of the most interesting materials whose nanostructure and hierarchical organization have been shown to correlate directly with favorable properties and their resulting applications.

  9. Customizable nanotweezers for manipulation of free-standing nanostructures

    DEFF Research Database (Denmark)

    Bøggild, Peter; Hansen, Torben Mikael; Mølhave, Kristian

    2001-01-01

    We present a novel nanotweezer device for manipulation and measurement of free-standing nanostructures, where the shape of the tweezer tips can be customized for the application. Electrostatic actuators with submicron interelectrode spacings are fabricated on a batch level using silicon microfabr...

  10. Development of nanostructured protective "sight glasses" for IR gas sensors

    DEFF Research Database (Denmark)

    Bergmann, René; Davis, Zachary James; Schmidt, Michael Stenbæk

    2011-01-01

    property of the surface could be enhanced, shown by contact angle and roll-off angle measurements. The "self-cleaning" surface property and chemical robustness towards aggressive environments are demonstrated. FT-IR spectroscopy concerning the optical properties of these nanostructured silicon windows...

  11. Thermoelectric effects in graphene nanostructures.

    Science.gov (United States)

    Dollfus, Philippe; Hung Nguyen, Viet; Saint-Martin, Jérôme

    2015-04-10

    The thermoelectric properties of graphene and graphene nanostructures have recently attracted significant attention from the physics and engineering communities. In fundamental physics, the analysis of Seebeck and Nernst effects is very useful in elucidating some details of the electronic band structure of graphene that cannot be probed by conductance measurements alone, due in particular to the ambipolar nature of this gapless material. For applications in thermoelectric energy conversion, graphene has two major disadvantages. It is gapless, which leads to a small Seebeck coefficient due to the opposite contributions of electrons and holes, and it is an excellent thermal conductor. The thermoelectric figure of merit ZT of a two-dimensional (2D) graphene sheet is thus very limited. However, many works have demonstrated recently that appropriate nanostructuring and bandgap engineering of graphene can concomitantly strongly reduce the lattice thermal conductance and enhance the Seebeck coefficient without dramatically degrading the electronic conductance. Hence, in various graphene nanostructures, ZT has been predicted to be high enough to make them attractive for energy conversion. In this article, we review the main results obtained experimentally and theoretically on the thermoelectric properties of graphene and its nanostructures, emphasizing the physical effects that govern these properties. Beyond pure graphene structures, we discuss also the thermoelectric properties of some hybrid graphene structures, as graphane, layered carbon allotropes such as graphynes and graphdiynes, and graphene/hexagonal boron nitride heterostructures which offer new opportunities. Finally, we briefly review the recent activities on other atomically thin 2D semiconductors with finite bandgap, i.e. dichalcogenides and phosphorene, which have attracted great attention for various kinds of applications, including thermoelectrics.

  12. Gallium arsenide/gold nanostructures deposited using plasma method

    Energy Technology Data Exchange (ETDEWEB)

    Mangla, O. [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Physics Department, Hindu College, University of Delhi, Delhi, 110007 (India); Roy, S. [Physics Department, Daulat Ram College, University of Delhi, Delhi, 110007, India. E-mail: savitaroy64@gmail.com (India); Annapoorni, S. [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India)

    2016-05-23

    The fabrication of gallium arsenide (GaAs) nanostructures on gold coated glass, quartz and silicon substrates using the high fluence and highly energetic ions has been reported. The high fluence and highly energetic ions are produced by the hot, dense and extremely non-equilibrium plasma in a modified dense plasma focus device. The nanostructures having mean size about 14 nm, 13 nm and 18 nm are deposited on gold coated glass, quartz and silicon substrates, respectively. The optical properties of nanostructures studied using absorption spectra show surface plasmon resonance peak of gold nanoparticles. In addition, the band-gap of GaAs nanoparticles is more than that of bulk GaAs suggesting potential applications in the field of optoelectronic and sensor systems.

  13. Process Development for Nanostructured Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Elam, Jeffrey W.

    2015-01-01

    Photovoltaic manufacturing is an emerging industry that promises a carbon-free, nearly limitless source of energy for our nation. However, the high-temperature manufacturing processes used for conventional silicon-based photovoltaics are extremely energy-intensive and expensive. This high cost imposes a critical barrier to the widespread implementation of photovoltaic technology. Argonne National Laboratory and its partners recently invented new methods for manufacturing nanostructured photovoltaic devices that allow dramatic savings in materials, process energy, and cost. These methods are based on atomic layer deposition, a thin film synthesis technique that has been commercialized for the mass production of semiconductor microelectronics. The goal of this project was to develop these low-cost fabrication methods for the high efficiency production of nanostructured photovoltaics, and to demonstrate these methods in solar cell manufacturing. We achieved this goal in two ways: 1) we demonstrated the benefits of these coatings in the laboratory by scaling-up the fabrication of low-cost dye sensitized solar cells; 2) we used our coating technology to reduce the manufacturing cost of solar cells under development by our industrial partners.

  14. Ultrafast all-optical switching and error-free 10 Gbit/s wavelength conversion in hybrid InP-silicon on insulator nanocavities using surface quantum wells

    International Nuclear Information System (INIS)

    Bazin, Alexandre; Monnier, Paul; Beaudoin, Grégoire; Sagnes, Isabelle; Raj, Rama; Lenglé, Kevin; Gay, Mathilde; Bramerie, Laurent; Braive, Rémy; Raineri, Fabrice

    2014-01-01

    Ultrafast switching with low energies is demonstrated using InP photonic crystal nanocavities embedding InGaAs surface quantum wells heterogeneously integrated to a silicon on insulator waveguide circuitry. Thanks to the engineered enhancement of surface non radiative recombination of carriers, switching time is obtained to be as fast as 10 ps. These hybrid nanostructures are shown to be capable of achieving systems level performance by demonstrating error free wavelength conversion at 10 Gbit/s with 6 mW switching powers

  15. Elongated nanostructures for radial junction solar cells.

    Science.gov (United States)

    Kuang, Yinghuan; Vece, Marcel Di; Rath, Jatindra K; Dijk, Lourens van; Schropp, Ruud E I

    2013-10-01

    In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

  16. Engineering a new class of thermal spray nano-based microstructures from agglomerated nanostructured particles, suspensions and solutions: an invited review

    International Nuclear Information System (INIS)

    Fauchais, P; Montavon, G; Lima, R S; Marple, B R

    2011-01-01

    From the pioneering works of McPherson in 1973 who identified nanometre-sized features in thermal spray conventional alumina coatings (using sprayed particles in the tens of micrometres size range) to the most recent and most advanced work aimed at manufacturing nanostructured coatings from nanometre-sized feedstock particles, the thermal spray community has been involved with nanometre-sized features and feedstock for more than 30 years. Both the development of feedstock (especially through cryo-milling, and processes able to manufacture coatings structured at the sub-micrometre or nanometre sizes, such as micrometre-sized agglomerates made of nanometre-sized particles for feedstock) and the emergence of thermal spray processes such as suspension and liquid precursor thermal spray techniques have been driven by the need to manufacture coatings with enhanced properties. These techniques result in two different types of coatings: on the one hand, those with a so-called bimodal structure having nanometre-sized zones embedded within micrometre ones, for which the spray process is similar to that of conventional coatings and on the other hand, sub-micrometre or nanostructured coatings achieved by suspension or solution spraying. Compared with suspension spraying, solution precursor spraying uses molecularly mixed precursors as liquids, avoiding a separate processing route for the preparation of powders and enabling the synthesis of a wide range of oxide powders and coatings. Such coatings are intended for use in various applications ranging from improved thermal barrier layers and wear-resistant surfaces to thin solid electrolytes for solid oxide fuel cell systems, among other numerous applications. Meanwhile these processes are more complex to operate since they are more sensitive to parameter variations compared with conventional thermal spray processes. Progress in this area has resulted from the unique combination of modelling activities, the evolution of

  17. The GEM Silicon Tracking System

    International Nuclear Information System (INIS)

    Mills, G.B.

    1993-01-01

    The GEM Collaboration has produced a baseline design for the GEM detector. The baseline design of the GEM Silicon Tracking System (STS) is discussed in this article. Mechanical and electrical engineering progress on the GEM STS is described. Results from simulations of detector performance and the implications on engineering issues are described

  18. Advanced Magnetic Nanostructures

    CERN Document Server

    Sellmyer, David

    2006-01-01

    Advanced Magnetic Nanostructures is devoted to the fabrication, characterization, experimental investigation, theoretical understanding, and utilization of advanced magnetic nanostructures. Focus is on various types of 'bottom-up' and 'top-down' artificial nanostructures, as contrasted to naturally occurring magnetic nanostructures, such as iron-oxide inclusions in magnetic rocks, and to structures such as perfect thin films. Chapter 1 is an introduction into some basic concepts, such as the definitions of basic magnetic quantities. Chapters 2-4 are devoted to the theory of magnetic nanostructures, Chapter 5 deals with the characterization of the structures, and Chapters 6-10 are devoted to specific systems. Applications of advanced magnetic nanostructures are discussed in Chapters11-15 and, finally, the appendix lists and briefly discusses magnetic properties of typical starting materials. Industrial and academic researchers in magnetism and related areas such as nanotechnology, materials science, and theore...

  19. Nanostructured composite reinforced material

    Science.gov (United States)

    Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  20. Low cost silicon solar array project silicon materials task

    Science.gov (United States)

    1977-01-01

    A program was established to develop a high temperature silicon production process using existing electric arc heater technology. Silicon tetrachloride and a reductant will be injected into an arc heated mixture of hydrogen and argon. Under these high temperature conditions, a very rapid reaction is expected to occur and proceed essentially to completion, yielding silicon and gaseous sodium chloride. Techniques for high temperature separation and collection of the molten silicon will be developed using standard engineering approaches, and the salt vapor will later be electrolytically separated into its elemental constituents for recycle. Preliminary technical evaluations and economic projections indicate not only that this process appears to be feasible, but that it also has the advantages of rapid, high capacity production of good quality molten silicon at a nominal cost.

  1. Nanostructured Materials for Magnetoelectronics

    CERN Document Server

    Mikailzade, Faik

    2013-01-01

    This book provides an up-to-date review of nanometer-scale magnetism and focuses on the investigation of the basic properties of magnetic nanostructures. It describes a wide range of physical aspects together with theoretical and experimental methods. A broad overview of the latest developments in this emerging and fascinating field of nanostructured materials is given with emphasis on the practical understanding and operation of submicron devices based on nanostructured magnetic materials.

  2. Engineering of Highly Susceptible Paramagnetic Nanostructures of Gd2S3:Eu3+: Potentially an Efficient Material for Room Temperature Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    Muhammed M. Radhi

    2010-11-01

    Full Text Available This research papers throws light into the compositional, morphological and structural properties of novel nanoparticles of Gd2S3:Eu3+ synthesized by a simple co-precipitation technique. Furthermore, we also prognosticate that this material could be useful for gas sensing applications at room temperature. Nanostructures formulation by this method resulted in the formation of orthorhombic crystal structure with primitive lattice having space group Pnma. The material characterizations are performed using X-ray diffraction (XRD, energy dispersive X-ray analysis (EDX, thermo-gravimetric analysis/differential thermal analysis (TGA/DTA and transmission electron microscope (TEM. The calculated crystallite sizes are ~ 2-5 nm and are in well accordance with the HRTEM results. EDX result confirms the presence and homogeneous distribution of Gd and Eu throughout the nanoparticle. The prepared nanoparticles exhibit strong paramagnetic nature with paramagnetic term, susceptibility c = 8.2 ´ 10-5 emg/g Gauss. TGA/DTA analysis shows 27 % weight loss with rise in temperature. The gas sensing capability of the prepared Gd2S3:Eu3+ magnetic nanoparticles are investigated using the amperometric method. These nanoparticles show good I-V characteristics with ideal semiconducting nature at room temperature with and without ammonia dose. The observed room temperature sensitivity with increasing dose of ammonia indicates applicability of Gd2S3 nanoparticles as room temperature ammonia sensors.

  3. Integration of functional complex oxide nanomaterials on silicon

    Directory of Open Access Journals (Sweden)

    Jose Manuel eVila-Fungueiriño

    2015-06-01

    Full Text Available The combination of standard wafer-scale semiconductor processing with the properties of functional oxides opens up to innovative and more efficient devices with high value applications that can be produced at large scale. This review uncovers the main strategies that are successfully used to monolithically integrate functional complex oxide thin films and nanostructures on silicon: the chemical solution deposition approach (CSD and the advanced physical vapor deposition techniques such as oxide molecular beam epitaxy (MBE. Special emphasis will be placed on complex oxide nanostructures epitaxially grown on silicon using the combination of CSD and MBE. Several examples will be exposed, with a particular stress on the control of interfaces and crystallization mechanisms on epitaxial perovskite oxide thin films, nanostructured quartz thin films, and octahedral molecular sieve nanowires. This review enlightens on the potential of complex oxide nanostructures and the combination of both chemical and physical elaboration techniques for novel oxide-based integrated devices.

  4. Report for fiscal 1998 on results of research and development of silicon-based polymeric material. Material research for the liquid methane fueled aircraft engine; 1998 nendo keisokei kobunshi zairyo no kenkyu kaihatsu seika hokokusho. Methane nenryo kokukiyo engine kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Research was conducted for the purpose of establishing basic technology concerning molecular design, synthesis, material formation, and evaluation of silicon-based polymers which are expected to provide superior electronic/optical functions, high heat/combustion resistance and dynamic properties. The research subjects were such as following: research and development of silicon-based polymeric materials with sea-island microstructures; research and development of silicon-based polymeric materials with sea-island microstructures; research and development on IPN formation with silicon-based polymers; research and development of hybrid silicon polymers with organometallic compounds; research and development of silicon containing polymer materials with ring structures; general committee for investigation and research; the optimized low-temperature Wurtz synthesis and modification of polysilanes; study of unsaturated and hypercoordinate organosilicon compounds; basic studies on the synthesis and properties of silicon-based high polymers; studies of new monomer-synthesis and their polymerization reaction; studies on new method of preparation and functionalization of polysilanes; novel applications of silicon-based polymers in imaging devices for information display, memory, and recordings; and molecular design of silicon-containing {pi}-conjugated and {sigma}-conjugated compounds. (NEDO)

  5. Influence of the Surface Layer on the Electrochemical Deposition of Metals and Semiconductors into Mesoporous Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chubenko, E. B., E-mail: eugene.chubenko@gmail.com; Redko, S. V.; Sherstnyov, A. I.; Petrovich, V. A.; Kotov, D. A.; Bondarenko, V. P. [Belarusian State University of Information and RadioElectronics (Belarus)

    2016-03-15

    The influence of the surface layer on the process of the electrochemical deposition of metals and semiconductors into porous silicon is studied. It is shown that the surface layer differs in structure and electrical characteristics from the host porous silicon bulk. It is established that a decrease in the conductivity of silicon crystallites that form the surface layer of porous silicon has a positive effect on the process of the filling of porous silicon with metals and semiconductors. This is demonstrated by the example of nickel and zinc oxide. The effect can be used for the formation of nanocomposite materials on the basis of porous silicon and nanostructures with a high aspect ratio.

  6. Nanostructured layers of thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Jeffrey J.; Lynch, Jared; Coates, Nelson; Forster, Jason; Sahu, Ayaskanta; Chabinyc, Michael; Russ, Boris

    2018-01-30

    This disclosure provides systems, methods, and apparatus related to thermoelectric materials. In one aspect, a method includes providing a plurality of nanostructures. The plurality of nanostructures comprise a thermoelectric material, with each nanostructure of the plurality of nanostructures having first ligands disposed on a surface of the nanostructure. The plurality of nanostructures is mixed with a solution containing second ligands and a ligand exchange process occurs in which the first ligands disposed on the plurality of nanostructures are replaced with the second ligands. The plurality of nanostructures is deposited on a substrate to form a layer. The layer is thermally annealed.

  7. Vibron and phonon hybridization in dielectric nanostructures.

    Science.gov (United States)

    Preston, Thomas C; Signorell, Ruth

    2011-04-05

    Plasmon hybridization theory has been an invaluable tool in advancing our understanding of the optical properties of metallic nanostructures. Through the prism of molecular orbital theory, it allows one to interpret complex structures as "plasmonic molecules" and easily predict and engineer their electromagnetic response. However, this formalism is limited to conducting particles. Here, we present a hybridization scheme for the external and internal vibrations of dielectric nanostructures that provides a straightforward understanding of the infrared signatures of these particles through analogy to existing hybridization models of both molecular orbitals and plasmons extending the range of applications far beyond metallic nanostructures. This method not only provides a qualitative understanding, but also allows for the quantitative prediction of vibrational spectra of complex nanoobjects from well-known spectra of their primitive building blocks. The examples of nanoshells illustrate how spectral features can be understood in terms of symmetry, number of nodal planes, and scale parameters.

  8. On the role of microstructure in governing the fatigue behaviour of nanostructured bainitic steels

    International Nuclear Information System (INIS)

    Rementeria, Rosalia; Morales-Rivas, Lucia; Kuntz, Matthias; Garcia-Mateo, Carlos; Kerscher, Eberhard; Sourmail, Thomas; Caballero, Francisca G.

    2015-01-01

    Nanostructured bainite is not a novel laboratory-scale steel anymore and the interest on the commercial production of these microstructures by steelmakers and end-users is now conceivable. These microstructures are achieved through the isothermal transformation of high-carbon high-silicon steels at low temperature, leading to nanoscale plates of ferrite with thickness of 20–40 nm and retained austenite. Nanostructured bainitic steels present the highest strength/toughness combinations ever recorded in bainitic steels (2.2 GPa/40 MPa m 1/2 ) and the potential for engineering components is alluring. However, fatigue properties, responsible of the durability of a component, remain to be examined. In order to understand the role of the microstructure during the fatigue crack propagation, the crack path in three nanoscale bainitic structures has been analysed on the basis of the relationships between grain misorientations and grain boundaries by Electron Backscatter Diffraction. Active slip systems in bainitic ferrite and crack deflection at grain boundaries have been identified, while retained austenite is cast doubt on its role

  9. Structural DNA Nanotechnology: Artificial Nanostructures for Biomedical Research.

    Science.gov (United States)

    Ke, Yonggang; Castro, Carlos; Choi, Jong Hyun

    2018-04-04

    Structural DNA nanotechnology utilizes synthetic or biologic DNA as designer molecules for the self-assembly of artificial nanostructures. The field is founded upon the specific interactions between DNA molecules, known as Watson-Crick base pairing. After decades of active pursuit, DNA has demonstrated unprecedented versatility in constructing artificial nanostructures with significant complexity and programmability. The nanostructures could be either static, with well-controlled physicochemical properties, or dynamic, with the ability to reconfigure upon external stimuli. Researchers have devoted considerable effort to exploring the usability of DNA nanostructures in biomedical research. We review the basic design methods for fabricating both static and dynamic DNA nanostructures, along with their biomedical applications in fields such as biosensing, bioimaging, and drug delivery. Expected final online publication date for the Annual Review of Biomedical Engineering Volume 20 is June 4, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  10. Thermal engineering of lead-free nanostructured CH3NH3SnCl3 perovskite material for thin-film solar cell

    Science.gov (United States)

    Moyez, Sk Abdul; Roy, Subhasis

    2018-01-01

    Perovskite solar cell is a kind of revolutionary investigation in the field of renewable energy which is capable of mitigates the deficiencies of silicon solar cell and its uprising efficiency can bring blessing to society. The presence of lead (Pb) in perovskite solar cell can make worst and negative impact on environment and is not desirable for our society. In this paper, general plans are anticipated by replacement of Pb with tin (Sn) in open atmosphere to fabricate the CH3NH3SnCl3 photovoltaic cells in chlorine (Cl)-rich environment. Excess uses of Cl has positive influences on morphological growth of the film and it also suppresses the oxidation tendency of tin (Sn) with existing oxygen in atmosphere and maintains same chemical atmosphere as bulk. Various characterization tools like X-ray diffraction, scanning electron microscope (SEM) have been used to study the effect of annealing temperature on crystal stricture, phase formation, impurities, and morphologies of the film. Finally, photovoltaic performance was reported using the solar simulator under 1.5 sun illumination.

  11. Nanostructured micro-electrode arrays for electrophysiological measurements

    DEFF Research Database (Denmark)

    Wierzbicki, Rafal Dominik

    -dimensional electrode arrays with features able to penetrate cell membrane are currently investigated by various groups. While a number of experimental setups have been recently developed, the question remains whether the nanostructure is in fact penetrating the cellular membrane, and if the measurements are indeed......, and cost-effectiveness of the fabrication. Secondly, I worked on a reliable imaging method that would be able to directly envision nanostructure-cell membrane interface. As a result, a novel maskless patterning method of CNT forests was invented, devices with multichannel arrays of electrodes with silicon...

  12. Silicon spintronics with ferromagnetic tunnel devices

    International Nuclear Information System (INIS)

    Jansen, R; Sharma, S; Dash, S P; Min, B C

    2012-01-01

    In silicon spintronics, the unique qualities of ferromagnetic materials are combined with those of silicon, aiming at creating an alternative, energy-efficient information technology in which digital data are represented by the orientation of the electron spin. Here we review the cornerstones of silicon spintronics, namely the creation, detection and manipulation of spin polarization in silicon. Ferromagnetic tunnel contacts are the key elements and provide a robust and viable approach to induce and probe spins in silicon, at room temperature. We describe the basic physics of spin tunneling into silicon, the spin-transport devices, the materials aspects and engineering of the magnetic tunnel contacts, and discuss important quantities such as the magnitude of the spin accumulation and the spin lifetime in the silicon. We highlight key experimental achievements and recent progress in the development of a spin-based information technology. (topical review)

  13. Organic nanostructured thin film devices and coatings for clean energy

    CERN Document Server

    Zhang, Sam

    2010-01-01

    Authored by leading experts from around the world, the three-volume Handbook of Nanostructured Thin Films and Coatings gives scientific researchers and product engineers a resource as dynamic and flexible as the field itself. The first two volumes cover the latest research and application of the mechanical and functional properties of thin films and coatings, while the third volume explores the cutting-edge organic nanostructured devices used to produce clean energy. This third volume, Organic Nanostructured Thin Film Devices and Coatings for Clean Energy, addresses various aspects of the proc

  14. Novel graphene-based nanostructures: physicochemical properties and applications

    International Nuclear Information System (INIS)

    Chernozatonskii, L A; Sorokin, P B; Artukh, A A

    2014-01-01

    The review concerns graphene-based nanostructures including graphene nanoribbons a few nanometres wide, structures functionalized with hydrogen and fluorine atoms as well as pure carbon composites. The physicochemical properties and the chemical engineering methods for their fabrication are considered. Methods for solving problems in modern nanotechnology are discussed. Possible applications of graphene and graphene-based nanostructures in various devices are outlined. The bibliography includes 286 references

  15. Adaptive IR Sensing Based on Advanced Nanostructures with Tunable Kinetics

    Science.gov (United States)

    2015-11-05

    AFRL-AFOSR-VA-TR-2015-0360 ADAPTIVE IR SENSING BASED ON ADVANCED NANOSTRUCTURES WITH TUNABLE KINETICS Vladimir Mitin RESEARCH FOUNDATION OF STATE...1 August 2010 - 31 July 2015 4. TITLE AND SUBTITLE Adaptive IR Sensing Based on Advanced Nanostructures with Tunable Kinetics 5a. CONTRACT NUMBER...engineering, and technological basis for further development of IR nanomaterials with nanoscale potential profile that can be effectively controlled by

  16. Halogenation dictates the architecture of amyloid peptide nanostructures.

    Science.gov (United States)

    Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W; Baldelli Bombelli, Francesca; Metrangolo, Pierangelo

    2017-07-20

    Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

  17. Electrochemical approach for monitoring the effect of anti tubulin drugs on breast cancer cells based on silicon nanograss electrodes.

    Science.gov (United States)

    Zanganeh, Somayeh; Khosravi, Safoora; Namdar, Naser; Amiri, Morteza Hassanpour; Gharooni, Milad; Abdolahad, Mohammad

    2016-09-28

    One of the most interested molecular research in the field of cancer detection is the mechanism of drug effect on cancer cells. Translating molecular evidence into electrochemical profiles would open new opportunities in cancer research. In this manner, applying nanostructures with anomalous physical and chemical properties as well as biocompatibility would be a suitable choice for the cell based electrochemical sensing. Silicon based nanostructure are the most interested nanomaterials used in electrochemical biosensors because of their compatibility with electronic fabrication process and well engineering in size and electrical properties. Here we apply silicon nanograss (SiNG) probing electrodes produced by reactive ion etching (RIE) on silicon wafer to electrochemically diagnose the effect of anticancer drugs on breast tumor cells. Paclitaxel (PTX) and mebendazole (MBZ) drugs have been used as polymerizing and depolymerizing agents of microtubules. PTX would perturb the anodic/cathodic responses of the cell-covered biosensor by binding phosphate groups to deformed proteins due to extracellular signal-regulated kinase (ERK(1/2)) pathway. MBZ induces accumulation of Cytochrome C in cytoplasm. Reduction of the mentioned agents in cytosol would change the ionic state of the cells monitored by silicon nanograss working electrodes (SiNGWEs). By extending the contacts with cancer cells, SiNGWEs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Effects of MBZ and PTX drugs, (with the concentrations of 2 nM and 0.1 nM, respectively) on electrochemical activity of MCF-7 cells are successfully recorded which are corroborated by confocal and flow cytometry assays. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Syringe siliconization process investigation and optimization.

    Science.gov (United States)

    Chan, Edwin; Hubbard, Aaron; Sane, Samir; Maa, Yuh-Fun

    2012-01-01

    syringe providers. However, its technical details and associated critical process parameters are rarely published. The purpose of this study is three-fold: (1) to reveal design details of a bench-top siliconization unit, (2) to identify critical process parameters and determine their optimum range to provide consistent and even silicone coating, and (3) to demonstrate the applicability of the optimum process condition derived from the bench-top unit to a pilot siliconization unit. The outcomes of this study will benefit scientists and engineers developing pre-filled syringe products by helping them to better understanding silicone spray coating principles and their relationship to siliconization processes in a large-scale manufacturing setting.

  19. Silicon technologies ion implantation and thermal treatment

    CERN Document Server

    Baudrant, Annie

    2013-01-01

    The main purpose of this book is to remind new engineers in silicon foundry, the fundamental physical and chemical rules in major Front end treatments: oxidation, epitaxy, ion implantation and impurities diffusion.

  20. Morphology and nano-structure analysis of soot particles sampled from high pressure diesel jet flames under diesel-like conditions

    Science.gov (United States)

    Jiang, Hao; Li, Tie; Wang, Yifeng; He, Pengfei

    2018-04-01

    Soot particles emitted from diesel engines have a significant impact on the atmospheric environment. Detailed understanding of soot formation and oxidation processes is helpful for reducing the pollution of soot particles, which requires information such as the size and nano-structure parameters of the soot primary particles sampled in a high-temperature and high-pressure diesel jet flame. Based on the thermophoretic principle, a novel sampling probe minimally disturbing the diesel jet flame in a constant volume combustion vessel is developed for analysing soot particles. The injected quantity of diesel fuel is less than 10 mg, and the soot particles sampled by carriers with a transmission electron microscope (TEM) grid and lacey TEM grid can be used to analyse the morphologies of soot aggregates and the nano-structure of the soot primary particles, respectively. When the quantity of diesel fuel is more than 10 mg, in order to avoid burning-off of the carriers in higher temperature and pressure conditions, single-crystal silicon chips are employed. Ultrasonic oscillations and alcohol extraction are then implemented to obtain high quality soot samples for observation using a high-resolution transmission electron microscope. An in-house Matlab-based code is developed to extract the nano-structure parameters of the soot particles. A complete sampling and analysis procedure of the soot particles is provided to study the formation and oxidation mechanism of soot.

  1. Broadband antireflective silicon carbide surface produced by cost-effective method

    DEFF Research Database (Denmark)

    Argyraki, Aikaterini; Ou, Yiyu; Ou, Haiyan

    2013-01-01

    A cost-effective method for fabricating antireflective subwavelength structures on silicon carbide is demonstrated. The nanopatterning is performed in a 2-step process: aluminum deposition and reactive ion etching. The effect, of the deposited aluminum film thickness and the reactive ion etching...... conditions, on the average surface reflectance and nanostructure landscape have been investigated systematically. The average reflectance of silicon carbide surface is significantly suppressed from 25.4% to 0.05%, under the optimal experimental conditions, in the wavelength range of 390-784 nm. The presence...... of stochastic nanostructures also changes the wetting properties of silicon carbide surface from hydrophilic (47°) to hydrophobic (108°)....

  2. Semiconductor nanostructures for plasma energetic systems

    Science.gov (United States)

    Mustafaev, Alexander; Smerdov, Rostislav; Klimenkov, Boris

    2017-10-01

    In this talk we discuss the research results of the three types of ultrasmall electrodes namely the nanoelectrode arrays based on composite nanostructured porous silicon (PS) layers, porous GaP and nanocrystals of ZnO. These semiconductor materials are of great interest to nano- and optoelectronic applications by virtue of their high specific surface area and extensive capability for surface functionalization. The use of semiconductor (GaN) cathodes in photon-enhanced thermionic emission systems has also proved to be effective although only a few (less than 1%) of the incident photons exceed the 3.3 eV GaN band gap. This significant drawback provided us with a solid foundation for our research in the field of nanostructured PS, and composite materials based on it exhibiting nearly optimal parameters in terms of the band gap (1.1 eV). The band gap modification for PS nanostructured layers is possible in the range of less than 1 eV and 3 eV due to the existence of quantum confinement effect and the remarkable possibilities of PS surface alteration thus providing us with a suitable material for both cathode and anode fabrication. The obtained results are applicable for solar concentration and thermionic energy conversion systems. Dr. Sci., Ph.D, Principal Scientist, Professor.

  3. Self-assembled nanostructures

    CERN Document Server

    Zhang, Jin Z; Liu, Jun; Chen, Shaowei; Liu, Gang-yu

    2003-01-01

    Nanostructures refer to materials that have relevant dimensions on the nanometer length scales and reside in the mesoscopic regime between isolated atoms and molecules in bulk matter. These materials have unique physical properties that are distinctly different from bulk materials. Self-Assembled Nanostructures provides systematic coverage of basic nanomaterials science including materials assembly and synthesis, characterization, and application. Suitable for both beginners and experts, it balances the chemistry aspects of nanomaterials with physical principles. It also highlights nanomaterial-based architectures including assembled or self-assembled systems. Filled with in-depth discussion of important applications of nano-architectures as well as potential applications ranging from physical to chemical and biological systems, Self-Assembled Nanostructures is the essential reference or text for scientists involved with nanostructures.

  4. Nanostructured CNx (0

    NARCIS (Netherlands)

    Bongiorno, G; Blomqvist, M; Piseri, P; Milani, P; Lenardi, C; Ducati, C; Caruso, T; Rudolf, P; Wachtmeister, S; Csillag, S; Coronel, E

    Nanostructured CNx thin films were prepared by supersonic cluster beam deposition (SCBD) and systematically characterized by transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The

  5. Electrochemical characterization of carbon coated bundle-type silicon nanorod for anode material in lithium ion secondary batteries

    International Nuclear Information System (INIS)

    Halim, Martin; Kim, Jung Sub; Choi, Jeong-Gil; Lee, Joong Kee

    2015-01-01

    Highlights: • Bundle-type silicon nanorods (BSNR) were synthesized by metal assisted chemical etching. • Novel bundle-type nanorods electrode showed self-relaxant characteristics. • The self-relaxant property was enhanced by increasing the silver concentration. • PAA binder enhanced the self-relaxant property of the silicon material. • Carbon coated BSNR (BSNR@C) has evidently provided better cycle performance. - Abstract: Nanostructured silicon synthesis by surface modification of commercial micro-powder silicon was investigated in order to reduce the maximum volume change over cycle. The surface of micro-powder silicon was modified using an Ag metal-assisted chemical etching technique to produce nanostructured material in the form of bundle-type silicon nanorods. The volume change of the electrode using the nanostructured silicon during cycle was investigated using an in-situ dilatometer. Our result shows that nanostructured silicon synthesized using this method showed a self-relaxant characteristic as an anode material for lithium ion battery application. Moreover, binder selection plays a role in enhancing self-relaxant properties during delithiation via strong hydrogen interaction on the surface of the silicon material. The nanostructured silicon was then coated with carbon from propylene gas and showed higher capacity retention with the use of polyacrylic acid (PAA) binder. While the nano-size of the pore diameter control may significantly affect the capacity fading of nanostructured silicon, it can be mitigated via carbon coating, probably due to the prevention of Li ion penetration into 10 nano-meter sized pores

  6. Computer modelling of the plasma chemistry and plasma-based growth mechanisms for nanostructured materials

    International Nuclear Information System (INIS)

    In this review paper, an overview is given of different modelling efforts for plasmas used for the formation and growth of nanostructured materials. This includes both the plasma chemistry, providing information on the precursors for nanostructure formation, as well as the growth processes itself. We limit ourselves to carbon (and silicon) nanostructures. Examples of the plasma modelling comprise nanoparticle formation in silane and hydrocarbon plasmas, as well as the plasma chemistry giving rise to carbon nanostructure formation, such as (ultra)nanocrystalline diamond ((U)NCD) and carbon nanotubes (CNTs). The second part of the paper deals with the simulation of the (plasma-based) growth mechanisms of the same carbon nanostructures, i.e. (U)NCD and CNTs, both by mechanistic modelling and detailed atomistic simulations.

  7. Fabrication and characterization of subwavelength nanostructures on freestanding GaN slab.

    Science.gov (United States)

    Wang, Yongjin; Hu, Fangren; Kanamori, Yoshiaki; Sameshima, Hidehisa; Hane, Kazuhiro

    2010-02-01

    We develop a novel way to fabricate subwavelength nanostructures on the freestanding GaN slab using a GaN-on-silicon system by combining self-assemble technique and backside thinning method. Silicon substrate beneath the GaN slab is removed by bulk silicon micromachining, generating the freestanding GaN slab and eliminating silicon absorption of the emitted light. Fast atom beam (FAB) etching is conducted to thin the freestanding GaN slab from the backside, reducing the number of confined modes inside the GaN slab. With self-assembled silica nanospheres acting as an etching mask, subwavelength nanostructures are realized on the GaN surface by FAB etching. The reflection losses at the GaN interfaces are thus suppressed. When the InGaN/GaN multiple quantum wells (MQWs) active layers are excited, the light extraction efficiency is significantly improved for the freestanding nanostructured GaN slab. This work provides a very practical approach to fabricate freestanding nanostructures on the GaN-on-silicon system for further improving the light extraction efficiency.

  8. Next generation structural silicone glazing

    Directory of Open Access Journals (Sweden)

    Charles D. Clift

    2015-06-01

    Full Text Available This paper presents an advanced engineering evaluation, using nonlinear analysis of hyper elastic material that provides significant improvement to structural silicone glazing (SSG design in high performance curtain wall systems. Very high cladding wind pressures required in hurricane zones often result in bulky SSG profile dimensions. Architectural desire for aesthetically slender curtain wall framing sight-lines in combination with a desire to reduce aluminium usage led to optimization of silicone material geometry for better stress distribution.To accomplish accurate simulation of predicted behaviour under structural load, robust stress-strain curves of the silicone material are essential. The silicone manufacturer provided physical property testing via a specialized laboratory protocol. A series of rigorous curve fit techniques were then made to closely model test data in the finite element computer analysis that accounts for nonlinear strain of hyper elastic silicone.Comparison of this advanced design technique to traditional SSG design highlights differences in stress distribution contours in the silicone material. Simplified structural engineering per the traditional SSG design method does not provide accurate forecasting of material and stress optimization as shown in the advanced design.Full-scale specimens subject to structural load testing were performed to verify the design capacity, not only for high wind pressure values, but also for debris impact per ASTM E1886 and ASTM E1996. Also, construction of the test specimens allowed development of SSG installation techniques necessitated by the unique geometry of the silicone profile. Finally, correlation of physical test results with theoretical simulations is made, so evaluation of design confidence is possible. This design technique will introduce significant engineering advancement to the curtain wall industry.

  9. Silicon Qubits

    Energy Technology Data Exchange (ETDEWEB)

    Ladd, Thaddeus D. [HRL Laboratories, LLC, Malibu, CA (United States); Carroll, Malcolm S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-28

    Silicon is a promising material candidate for qubits due to the combination of worldwide infrastructure in silicon microelectronics fabrication and the capability to drastically reduce decohering noise channels via chemical purification and isotopic enhancement. However, a variety of challenges in fabrication, control, and measurement leaves unclear the best strategy for fully realizing this material’s future potential. In this article, we survey three basic qubit types: those based on substitutional donors, on metal-oxide-semiconductor (MOS) structures, and on Si/SiGe heterostructures. We also discuss the multiple schema used to define and control Si qubits, which may exploit the manipulation and detection of a single electron charge, the state of a single electron spin, or the collective states of multiple spins. Far from being comprehensive, this article provides a brief orientation to the rapidly evolving field of silicon qubit technology and is intended as an approachable entry point for a researcher new to this field.

  10. Genesis of nanostructured, magnetically tunable ceramics from the pyrolysis of cross-linked polyferrocenylsilane networks and formation of shaped macroscopic objects and micron scale patterns by micromolding inside silicon wafers.

    Science.gov (United States)

    Ginzburg, Madlen; MacLachlan, Mark J; Yang, San Ming; Coombs, Neil; Coyle, Thomas W; Raju, Nandyala P; Greedan, John E; Herber, Rolfe H; Ozin, Geoffrey A; Manners, Ian

    2002-03-20

    The ability to form molded or patterned metal-containing ceramics with tunable properties is desirable for many applications. In this paper we describe the evolution of a ceramic from a metal-containing polymer in which the variation of pyrolysis conditions facilitates control of ceramic structure and composition, influencing magnetic and mechanical properties. We have found that pyrolysis under nitrogen of a well-characterized cross-linked polyferrocenylsilane network derived from the ring-opening polymerization (ROP) of a spirocyclic [1]ferrocenophane precursor gives shaped macroscopic magnetic ceramics consisting of alpha-Fe nanoparticles embedded in a SiC/C/Si(3)N(4) matrix in greater than 90% yield up to 1000 degrees C. Variation of the pyrolysis temperature and time permitted control over the nucleation and growth of alpha-Fe particles, which ranged in size from around 15 to 700 A, and the crystallization of the surrounding matrix. The ceramics contained smaller alpha-Fe particles when prepared at temperatures lower than 900 degrees C and displayed superparamagnetic behavior, whereas the materials prepared at 1000 degrees C contained larger alpha-Fe particles and were ferromagnetic. This flexibility may be useful for particular materials applications. In addition, the composition of the ceramic was altered by changing the pyrolysis atmosphere to argon, which yielded ceramics that contain Fe(3)Si(5). The ceramics have been characterized by a combination of physical techniques, including powder X-ray diffraction, TEM, reflectance UV-vis/near-IR spectroscopy, elemental analysis, XPS, SQUID magnetometry, Mössbauer spectroscopy, nanoindentation, and SEM. Micromolding of the spirocyclic [1]ferrocenophane precursor within soft lithographically patterned channels housed inside silicon wafers followed by thermal ROP and pyrolysis enabled the formation of predetermined micron scale designs of the magnetic ceramic.

  11. Engineered optical properties of silver-aluminum alloy nanoparticles embedded in SiON matrix for maximizing light confinement in plasmonic silicon solar cells.

    Science.gov (United States)

    Parashar, Piyush K; Komarala, Vamsi K

    2017-10-02

    Self-assembled silver-aluminum (Ag-Al) alloy nanoparticles (NPs) embedded in SiO 2 , Si 3 N 4, and SiON dielectric thin film matrices explored as a hybrid plasmonic structure for silicon solar cells to maximize light confinement. The Ag 2 Al NPs prepared by ex-vacuo solid-state dewetting, and alloy formation confirmed by X-ray diffraction and photoelectron spectroscopy analysis. Nanoindentation by atomic force microscopy revealed better surface adhesion of alloy NPs on silicon surface than Ag NPs due to the Al presence. The SiON spacer layer/Ag 2 Al NPs reduced silicon average reflectance from 22.7% to 9.2% due to surface plasmonic and antireflection effects. The SiON capping layer on NPs reduced silicon reflectance from 9.2% to 3.6% in wavelength region 300-1150 nm with preferential forward light scattering due to uniform Coulombic restoring force on NPs' surface. Minimum reflectance and parasitic absorptance from 35 nm SiON/Ag 2 Al NPs/25 nm SiON structure reflected in plasmonic cell's photocurrent enhancement from 26.27 mA/cm 2 (of bare cell) to 34.61 mA/cm 2 due to the better photon management. Quantum efficiency analysis also showed photocurrent enhancement of cell in surface plasmon resonance and off-resonance regions of NPs. We also quantified dielectric thin film antireflection and alloy NPs plasmonic effects separately in cell photocurrent enhancement apart from hybrid plasmonic structure role.

  12. Upconversion in Nanostructured Materials: From Optical Tuning to Biomedical Applications.

    Science.gov (United States)

    Sun, Tianying; Ai, Fujin; Zhu, Guangyu; Wang, Feng

    2018-02-16

    Photon upconversion that is characterized by high-energy photon emission followed by lower-energy excitation has been conventionally studied in bulk materials for several decades. This unique nonlinear luminescence process has become a subject of great attention since 2000 when upconverted emission was demonstrated in nanostructured crystals. In comparison with their bulk counterparts, nanostructured materials provide more room for optical fine-tuning by allowing flexible compositional integration and structural engineering. Moreover, the high colloidal stability of nanoparticles coupled with high amenability to surface functionalization opens up a number of new applications for upconversion, especially in the fields of biology and life science. In this focus review, we discuss recent developments in upconversion materials through nanostructural design and review emerging biomedical applications that involve these nanostructured upconversion materials. We also attempt to highlight challenging problems of these nanomaterials that constrain further progress in utilizing upconversion processes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Deposition of DNA Nanostructures on Highly Oriented Pyrolytic Graphite.

    Science.gov (United States)

    Ricardo, Karen B; Xu, Anqin; Salim, Muhammad; Zhou, Feng; Liu, Haitao

    2017-04-25

    We report the deposition of DNA origami nanostructures on highly oriented pyrolytic graphite (HOPG). The DNA origami goes through a structural rearrangement and the DNA base is exposed to interact with the graphite surface. Exposure to ambient air, which is known to result in a hydrophilic-to-hydrophobic wetting transition of HOPG, does not significantly impact the deposition yield or the shape deformation of DNA nanostructures. The deposited DNA nanostructures maintain their morphology for at least a week and promote site-selective chemical vapor deposition of SiO 2 . This process is potentially useful for a range of applications that include but are not limited to nanostructure fabrication, sensing, and electronic and surface engineering.

  14. Selective Functionalization of Tailored Nanostructures

    NARCIS (Netherlands)

    Slingenbergh, Winand; Boer, Sanne K. de; Cordes, Thorben; Browne, Wesley R.; Feringa, Ben L.; Hoogenboom, Jacob P.; Hosson, Jeff Th.M. De; Dorp, Willem F. van

    2012-01-01

    The controlled positioning of nanostructures with active molecular components is of importance throughout nanoscience and nanotechnology. We present a novel three-step method to produce nanostructures that are selectively decorated with functional molecules. We use fluorophores and nanoparticles to

  15. Nanostructured materials in potentiometry.

    Science.gov (United States)

    Düzgün, Ali; Zelada-Guillén, Gustavo A; Crespo, Gastón A; Macho, Santiago; Riu, Jordi; Rius, F Xavier

    2011-01-01

    Potentiometry is a very simple electrochemical technique with extraordinary analytical capabilities. It is also well known that nanostructured materials display properties which they do not show in the bulk phase. The combination of the two fields of potentiometry and nanomaterials is therefore a promising area of research and development. In this report, we explain the fundamentals of potentiometric devices that incorporate nanostructured materials and we highlight the advantages and drawbacks of combining nanomaterials and potentiometry. The paper provides an overview of the role of nanostructured materials in the two commonest potentiometric sensors: field-effect transistors and ion-selective electrodes. Additionally, we provide a few recent examples of new potentiometric sensors that are based on receptors immobilized directly onto the nanostructured material surface. Moreover, we summarize the use of potentiometry to analyze processes involving nanostructured materials and the prospects that the use of nanopores offer to potentiometry. Finally, we discuss several difficulties that currently hinder developments in the field and some future trends that will extend potentiometry into new analytical areas such as biology and medicine.

  16. Plasmonic and silicon spherical nanoparticle antireflective coatings.

    Science.gov (United States)

    Baryshnikova, K V; Petrov, M I; Babicheva, V E; Belov, P A

    2016-03-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

  17. Molecular separations using nanostructured porous thin films fabricated by glancing angle deposition

    Science.gov (United States)

    Bezuidenhout, Louis Wentzel

    Biomolecular separation techniques are an enabling technology that indirectly in.uence many aspects of our lives. Advances have led to faster analyses, reduced costs, higher specificity, and new analytical techniques, impacting areas such as health care, environmental monitoring, polymer sciences, agriculture, and nutrition. Further development of separations technology is anticipated to follow the path of computing technology such that miniaturization through the development of microfluidics technology, lab-on-a-chip systems, and other integrative, multi-component systems will further extend our analysis capabilities. Creation of new and improvement of existing separation technologies is an integral part of the pathway to miniaturized systems. the work of this thesis investigates molecular separations using porous nanostructured films fabricated by the thin film process glancing angle deposition (GLAD). Structural architecture, pore size and shape, and film density can be finely controlled to produce high-surface area thin films with engineered morphology. The characteristic size scales and structural control of GLAD films are well-suited to biomolecules and separation techniques, motivating investigation into the utility and performance of GLAD films for biomolecular separations. This project consisted of three phases. First, chromatographic separation of dye molecules on silica GLAD films was demonstrated by thin layer chromatography Direct control of film nanostructure altered the separation characteristics; most strikingly, anisotropic structures provided two-dimensional analyte migration. Second, nanostructures made with GLAD were integrated in PDMS microfluidic channels using a sacrificial etching process; DNA molecules (10/48 kbp and 6/10/20 kbp mixtures) were electrophoretically separated on a microfluidic chip using a porous bed of SiO2 vertical posts. Third, mass spectrometry of proteins and drugs in the mass range of 100-1300 m/z was performed using

  18. Nanostructured electronic and magnetic materials

    Indian Academy of Sciences (India)

    Research and development in nanostructured materials is one of the most intensely studied areas in science. As a result of concerted R & D efforts, nanostructured electronic and magnetic materials have achieved commercial success. Specific examples of novel industrially important nanostructured electronic and magnetic ...

  19. Nanoscale semiconducting silicon as a nutritional food additive

    International Nuclear Information System (INIS)

    Canham, L T

    2007-01-01

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study

  20. Chiral Inorganic Nanostructures.

    Science.gov (United States)

    Ma, Wei; Xu, Liguang; de Moura, André F; Wu, Xiaoling; Kuang, Hua; Xu, Chuanlai; Kotov, Nicholas A

    2017-06-28

    The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of individual nanoparticles (NPs) and their assemblies and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others. Multiple chiral geometries were observed with characteristic scales from ångströms to microns. Uniquely high values of chiral anisotropy factors that spurred the development of the field and differentiate it from chiral structures studied before, are now well understood; they originate from strong resonances of incident electromagnetic waves with plasmonic and excitonic states typical for metals and semiconductors. At the same time, distinct similarities with chiral supramolecular and biological systems also emerged. They can be seen in the synthesis and separation methods, chemical properties of individual NPs, geometries of the nanoparticle assemblies, and interactions with biological membranes. Their analysis can help us understand in greater depth the role of chiral asymmetry in nature inclusive of both earth and space. Consideration of both differences and similarities between chiral inorganic, organic, and biological nanostructures will also accelerate the development of technologies based on chiroplasmonic and chiroexcitonic effects. This review will cover both experiment and theory of chiral nanostructures starting with the origin and multiple components of mirror asymmetry of individual NPs and their assemblies. We shall consider four different types of chirality in nanostructures and related physical, chemical, and

  1. Nanotechnology for chemical engineers

    CERN Document Server

    Salaheldeen Elnashaie, Said; Hashemipour Rafsanjani, Hassan

    2015-01-01

    The book describes the basic principles of transforming nano-technology into nano-engineering with a particular focus on chemical engineering fundamentals. This book provides vital information about differences between descriptive technology and quantitative engineering for students as well as working professionals in various fields of nanotechnology. Besides chemical engineering principles, the fundamentals of nanotechnology are also covered along with detailed explanation of several specific nanoscale processes from chemical engineering point of view. This information is presented in form of practical examples and case studies that help the engineers and researchers to integrate the processes which can meet the commercial production. It is worth mentioning here that, the main challenge in nanostructure and nanodevices production is nowadays related to the economic point of view. The uniqueness of this book is a balance between important insights into the synthetic methods of nano-structures and nanomaterial...

  2. Nanostructured piezoelectric energy harvesters

    CERN Document Server

    Briscoe, Joe

    2014-01-01

    This book covers a range of devices that use piezoelectricity to convert mechanical deformation into electrical energy and relates their output capabilities to a range of potential applications. Starting with a description of the fundamental principles and properties of piezo- and ferroelectric materials, where applications of bulk materials are well established, the book shows how nanostructures of these materials are being developed for energy harvesting applications. The authors show how a nanostructured device can be produced, and put in context some of the approaches that are being invest

  3. Magneto-Plasmonic Properties of Au/Fe/Au Planar Nanostructures: Theory and Experiments

    Czech Academy of Sciences Publication Activity Database

    Vlček, J.; Lesňák, M.; Otipka, P.; Sobota, Jaroslav

    2016-01-01

    Roč. 12, č. 1 (2016), s. 136-141 ISSN 2211-8128 Institutional support: RVO:68081731 Keywords : magneto-plasmonics * planar nanostructures * response factors Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  4. Thermo-plasmonics of Irradiated Metallic Nanostructures

    DEFF Research Database (Denmark)

    Ma, Haiyan

    Thermo-plasmonics is an emerging field in photonics which aims at harnessing the kinetic energy of light to generate nanoscopic sources of heat. Localized surface plasmons (LSP) supported by metallic nanostructures greatly enhance the interactions of light with the structure. By engineering...... the size, morphology and composition of metallic nanostructures, the absorption of light can be maximized, resulting in a substantial temperature elevation in a nanoscopic volume. Applications of these nanoscopic sources of heat can be found in various contexts including localized cancer therapy, drug...... using conventional techniques. In this thesis, we present novel experimental and numerical tools to characterize thermo-plasmonic devices in a biologically relevant environment, and explore the thermodiffusion properties and measure thermophoretic forces for particles in temperature gradients ranging...

  5. Simulataneous Formation of InGaN Nanostructures with Varying Shapes for White Light Source Applications

    KAUST Repository

    Gasim, Anwar A.

    2012-01-01

    Varying shapes of InGaN nanostructures were simultaneously formed on silicon epitaxially. The nanowires and nanomushrooms emit violet-blue light, and broad yellow-orange-red luminescence, respectively. The combination of which is promising for white light emission.

  6. Synthesis of ZnO comb-like nanostructures for high sensitivity H2S ...

    Indian Academy of Sciences (India)

    Zinc oxide (ZnO) comb-like nanostructures were successfully synthesized on the silicon substrate without a catalyst via chemical vapour deposition. The morphology and crystal structure of the product were characterized by scanning electron microscope and X-ray diffractometer. In this research, a simple gas sensor was ...

  7. Synthesis of ZnO comb-like nanostructures for high sensitivity H2S ...

    Indian Academy of Sciences (India)

    2017-09-15

    Sep 15, 2017 ... Abstract. Zinc oxide (ZnO) comb-like nanostructures were successfully synthesized on the silicon substrate without a catalyst via chemical vapour deposition. The morphology and crystal structure of the product were characterized by scanning electron microscope and X-ray diffractometer. In this research, a ...

  8. Nanostructure Engineering Using Electron Beam Lithography

    National Research Council Canada - National Science Library

    Fischer, Paul

    1993-01-01

    ...) system created by modifying a scanning electron microscope. (2) The exploration of minimum achievable feature sizes using ultra-high resolution EBL and a lift-off process with polymethyl-methacrylate resists...

  9. Epitaxial growth of hybrid nanostructures

    Science.gov (United States)

    Tan, Chaoliang; Chen, Junze; Wu, Xue-Jun; Zhang, Hua

    2018-02-01

    Hybrid nanostructures are a class of materials that are typically composed of two or more different components, in which each component has at least one dimension on the nanoscale. The rational design and controlled synthesis of hybrid nanostructures are of great importance in enabling the fine tuning of their properties and functions. Epitaxial growth is a promising approach to the controlled synthesis of hybrid nanostructures with desired structures, crystal phases, exposed facets and/or interfaces. This Review provides a critical summary of the state of the art in the field of epitaxial growth of hybrid nanostructures. We discuss the historical development, architectures and compositions, epitaxy methods, characterization techniques and advantages of epitaxial hybrid nanostructures. Finally, we provide insight into future research directions in this area, which include the epitaxial growth of hybrid nanostructures from a wider range of materials, the study of the underlying mechanism and determining the role of epitaxial growth in influencing the properties and application performance of hybrid nanostructures.

  10. Fabrication of single-crystal silicon nanotubes with sub-10 nm walls using cryogenic inductively coupled plasma reactive ion etching

    Science.gov (United States)

    Li, Zhiqin; Chen, Yiqin; Zhu, Xupeng; Zheng, Mengjie; Dong, Fengliang; Chen, Peipei; Xu, Lihua; Chu, Weiguo; Duan, Huigao

    2016-09-01

    Single-crystal silicon nanostructures have attracted much attention in recent years due in part to their unique optical properties. In this work, we demonstrate direct fabrication of single-crystal silicon nanotubes with sub-10 nm walls which show low reflectivity. The fabrication was based on a cryogenic inductively coupled plasma reactive ion etching process using high-resolution hydrogen silsesquioxane nanostructures as the hard mask. Two main etching parameters including substrate low-frequency power and SF6/O2 flow rate ratio were investigated to determine the etching mechanism in the process. With optimized etching parameters, high-aspect-ratio silicon nanotubes with smooth and vertical sub-10 nm walls were fabricated. Compared to commonly-used antireflection silicon nanopillars with the same feature size, the densely packed silicon nanotubes possessed a lower reflectivity, implying possible potential applications of silicon nanotubes in photovoltaics.

  11. Nanostructured catalyst supports

    Science.gov (United States)

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2012-10-02

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  12. Nanostructures-History

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Nanostructures-History. Inspiration to Nanotechnology-. The Japanese scientist Norio Taniguchi of the Tokyo University of Science was used the term "nano-technology" in a 1974 conference, to describe semiconductor processes such as thin film His definition was, ...

  13. A silicon tracker for Christmas

    CERN Multimedia

    2008-01-01

    The CMS experiment installed the world’s largest silicon tracker just before Christmas. Marcello Mannelli: physicist and deputy CMS project leader, and Alan Honma, physicist, compare two generations of tracker: OPAL for the LEP (at the front) and CMS for the LHC (behind). There is quite a difference between 1m2 and 205m2.. CMS received an early Christmas present on 18 December when the silicon tracker was installed in the heart of the CMS magnet. The CMS tracker team couldn’t have hoped for a better present. Carefully wrapped in shiny plastic, the world’s largest silicon tracker arrived at Cessy ready for installation inside the CMS magnet on 18 December. This rounded off the year for CMS with a major event, the crowning touch to ten years of work on the project by over five hundred scientists and engineers. "Building a scientific instrument of this size and complexity is a huge technical a...

  14. Thermal conductivity engineering of bulk and one-dimensional Si-Ge nanoarchitectures.

    Science.gov (United States)

    Kandemir, Ali; Ozden, Ayberk; Cagin, Tahir; Sevik, Cem

    2017-01-01

    Various theoretical and experimental methods are utilized to investigate the thermal conductivity of nanostructured materials; this is a critical parameter to increase performance of thermoelectric devices. Among these methods, equilibrium molecular dynamics (EMD) is an accurate technique to predict lattice thermal conductivity. In this study, by means of systematic EMD simulations, thermal conductivity of bulk Si-Ge structures (pristine, alloy and superlattice) and their nanostructured one dimensional forms with square and circular cross-section geometries (asymmetric and symmetric) are calculated for different crystallographic directions. A comprehensive temperature analysis is evaluated for selected structures as well. The results show that one-dimensional structures are superior candidates in terms of their low lattice thermal conductivity and thermal conductivity tunability by nanostructuring, such as by diameter modulation, interface roughness, periodicity and number of interfaces. We find that thermal conductivity decreases with smaller diameters or cross section areas. Furthermore, interface roughness decreases thermal conductivity with a profound impact. Moreover, we predicted that there is a specific periodicity that gives minimum thermal conductivity in symmetric superlattice structures. The decreasing thermal conductivity is due to the reducing phonon movement in the system due to the effect of the number of interfaces that determine regimes of ballistic and wave transport phenomena. In some nanostructures, such as nanowire superlattices, thermal conductivity of the Si/Ge system can be reduced to nearly twice that of an amorphous silicon thermal conductivity. Additionally, it is found that one crystal orientation, [Formula: see text]100[Formula: see text], is better than the [Formula: see text]111[Formula: see text] crystal orientation in one-dimensional and bulk SiGe systems. Our results clearly point out the importance of lattice thermal conductivity

  15. Comparative analysis of nanostructured diblock copolymer films

    International Nuclear Information System (INIS)

    Mueller-Buschbaum, P.; Hermsdorf, N.; Roth, S.V.; Wiedersich, J.; Cunis, S.; Gehrke, R.

    2004-01-01

    Nanostructured polymer films of poly(styrene-block-paramethylstyrene) diblock copolymers P(Sd-b-pMS) on silicon substrates with a native oxide layer are investigated. Resulting from a storage under toluene vapor, a surface structure is installed. The early stages, characterized by the creation of a host structure out of an initially continuous film, are addressed. Grazing incidence small-angle X-ray scattering (GISAXS) experiments were performed as a function of exposure time. Results are compared to modelling of the scattering pattern and other experimental techniques, such as grazing incidence small-angle neutron scattering (GISANS) and atomic force microscopy (AFM) data. Possibilities and limits of the techniques are discussed

  16. Nanostructural characterization of amorphous diamondlike carbon films

    Energy Technology Data Exchange (ETDEWEB)

    SIEGAL,MICHAEL P.; TALLANT,DAVID R.; MARTINEZ-MIRANDA,L.J.; BARBOUR,J. CHARLES; SIMPSON,REGINA L.; OVERMYER,DONALD L.

    2000-01-27

    Nanostructural characterization of amorphous diamondlike carbon (a-C) films grown on silicon using pulsed-laser deposition (PLD) is correlated to both growth energetic and film thickness. Raman spectroscopy and x-ray reflectivity probe both the topological nature of 3- and 4-fold coordinated carbon atom bonding and the topographical clustering of their distributions within a given film. In general, increasing the energetic of PLD growth results in films becoming more ``diamondlike'', i.e. increasing mass density and decreasing optical absorbance. However, these same properties decrease appreciably with thickness. The topology of carbon atom bonding is different for material near the substrate interface compared to material within the bulk portion of an a-C film. A simple model balancing the energy of residual stress and the free energies of resulting carbon topologies is proposed to provide an explanation of the evolution of topographical bonding clusters in a growing a-C film.

  17. Biologically inspired LED lens from cuticular nanostructures of firefly lantern

    Science.gov (United States)

    Kim, Jae-Jun; Lee, Youngseop; Kim, Ha Gon; Choi, Ki-Ju; Kweon, Hee-Seok; Park, Seongchong; Jeong, Ki-Hun

    2012-01-01

    Cuticular nanostructures found in insects effectively manage light for light polarization, structural color, or optical index matching within an ultrathin natural scale. These nanostructures are mainly dedicated to manage incoming light and recently inspired many imaging and display applications. A bioluminescent organ, such as a firefly lantern, helps to out-couple light from the body in a highly efficient fashion for delivering strong optical signals in sexual communication. However, the cuticular nanostructures, except the light-producing reactions, have not been well investigated for physical principles and engineering biomimetics. Here we report a unique observation of high-transmission nanostructures on a firefly lantern and its biological inspiration for highly efficient LED illumination. Both numerical and experimental results clearly reveal high transmission through the nanostructures inspired from the lantern cuticle. The nanostructures on an LED lens surface were fabricated by using a large-area nanotemplating and reconfigurable nanomolding with heat-induced shear thinning. The biologically inspired LED lens, distinct from a smooth surface lens, substantially increases light transmission over visible ranges, comparable to conventional antireflection coating. This biological inspiration can offer new opportunities for increasing the light extraction efficiency of high-power LED packages. PMID:23112185

  18. Parametric optimization for the low cost production of nanostructure ...

    African Journals Online (AJOL)

    user

    In recent years, nanocrystalline materials have drawn the attention of researchers in the field of materials science engineering due to its .... papers of 220 – 1200 grit size followed by a sequence of 3, 2µm diamond abrasive slurry. ..... Synthesis of nanostructured aluminum matrix composite (AMC) through machining,.

  19. Development of gas sensors using ZnO nanostructures

    Indian Academy of Sciences (India)

    Administrator

    *For correspondence. Development of gas sensors using ZnO nanostructures. S K GUPTA. 1,. *, ADITEE JOSHI. 2 and MANMEET KAUR. 1. 1. Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre,. Mumbai 400 085. 2. Department of Electronics Science, University of Pune, Pune 411 007.

  20. Thermodynamic aspects of nanostructured Ti5Si3 formation during ...

    Indian Academy of Sciences (India)

    Thermodynamic aspects of nanostructured Ti5Si3 formation during mechanical alloying and its characterization. S SABOONI, F KARIMZADEH. ∗ and M H ABBASI. Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan, Iran. MS received 2 April 2011; revised 3 August 2011. Abstract.

  1. Graphene-on-silicon hybrid plasmonic-photonic integrated circuits

    Science.gov (United States)

    Xiao, Ting-Hui; Cheng, Zhenzhou; Goda, Keisuke

    2017-06-01

    Graphene surface plasmons (GSPs) have shown great potential in biochemical sensing, thermal imaging, and optoelectronics. To excite GSPs, several methods based on the near-field optical microscope and graphene nanostructures have been developed in the past few years. However, these methods suffer from their bulky setups and low GSP-excitation efficiency due to the short interaction length between free-space vertical excitation light and the atomic layer of graphene. Here we present a CMOS-compatible design of graphene-on-silicon hybrid plasmonic-photonic integrated circuits that achieve the in-plane excitation of GSP polaritons as well as localized surface plasmon (SP) resonance. By employing a suspended membrane slot waveguide, our design is able to excite GSP polaritons on a chip. Moreover, by utilizing a graphene nanoribbon array, we engineer the transmission spectrum of the waveguide by excitation of localized SP resonance. Our theoretical and computational study paves a new avenue to enable, modulate, and monitor GSPs on a chip, potentially applicable for the development of on-chip electro-optic devices.

  2. Recycling of silicon: from industrial waste to biocompatible nanoparticles for nanomedicine

    Science.gov (United States)

    Kozlov, N. K.; Natashina, U. A.; Tamarov, K. P.; Gongalsky, M. B.; Solovyev, V. V.; Kudryavtsev, A. A.; Sivakov, V.; Osminkina, L. A.

    2017-09-01

    The formation of photoluminescent porous silicon (PSi) nanoparticles (NPs) is usually based on an expensive semiconductor grade wafers technology. Here, we report a low-cost method of PSi NPs synthesis from the industrial silicon waste remained after the wafer production. The proposed method is based on metal-assisted wet-chemical etching (MACE) of the silicon surface of cm-sized metallurgical grade silicon stones which leads to a nanostructuring of the surface due to an anisotropic etching, with subsequent ultrasound fracturing in water. The obtained PSi NPs exhibit bright red room temperature photoluminescence (PL) and demonstrate similar microstructure and physical characteristics in comparison with the nanoparticles synthesized from semiconductor grade Si wafers. PSi NPs prepared from metallurgical grade silicon stones, similar to silicon NPs synthesized from high purity silicon wafer, show low toxicity to biological objects that open the possibility of using such type of NPs in nanomedicine.

  3. Femtosecond laser-induced periodic nanostructure creation on PET surface for controlling of cell spreading

    Science.gov (United States)

    Sato, Yuji; Tsukamoto, Masahiro; Shinonaga, Togo; Kawa, Takuya

    2016-03-01

    A new method of periodic nanostructure formation on a polyethylene terephthalate (PET) surface has been developed, employing a femtosecond laser with a wavelength of 1045 nm. To generate structured films, the PET was placed in contact with a silicon (Si) wafer, followed by irradiation with the laser focused on the Si wafer, passing through the PET film. In order to evaluate the surface morphology, atomic force microscopy analysis was conducted on both treated and untreated PET surfaces. From the results, nanostructures with a period of 600 nm and height of 100 nm were formed on the PET film surface by laser treatment. A cell cultivation test was carried out on PET films with and without periodic nanostructures, showing that for nanostructured films, the cells (MG-63) were spread along the periodic grooves; in contrast, random cell spreading was observed for cultures grown on the untreated PET film.

  4. Nanostructured Electrochemical Biosensors for Label-Free Detection of Water- and Food-Borne Pathogens.

    Science.gov (United States)

    Reta, Nekane; Saint, Christopher P; Michelmore, Andrew; Prieto-Simon, Beatriz; Voelcker, Nicolas H

    2018-02-21

    The emergence of nanostructured materials has opened new horizons in the development of next generation biosensors. Being able to control the design of the electrode interface at the nanoscale combined with the intrinsic characteristics of the nanomaterials engenders novel biosensing platforms with improved capabilities. The purpose of this review is to provide a comprehensive and critical overview of the latest trends in emerging nanostructured electrochemical biosensors. A detailed description and discussion of recent approaches to construct label-free electrochemical nanostructured electrodes is given with special focus on pathogen detection for environmental monitoring and food safety. This includes the use of nanoscale materials such as nanotubes, nanowires, nanoparticles, and nanosheets as well as porous nanostructured materials including nanoporous anodic alumina, mesoporous silica, porous silicon, and polystyrene nanochannels. These platforms may pave the way toward the development of point-of-care portable electronic devices for applications ranging from environmental analysis to biomedical diagnostics.

  5. Preparation and integration of nanostructured titanium dioxide

    KAUST Repository

    Zeng, Hua Chun

    2011-10-01

    Titanium dioxide (TiO2) is a chemically stable nontoxic transition-metal oxide associated with a wide range of existing chemical engineering processes. In this short review, recent research endeavors in preparation and integration of nanostructured TiO2 materials system will be featured and discussed for their potential new applications. Because material development always plays pivotal roles in the progress of a particular engineering discipline, the reviewed subjects will provide useful information to stimulate nanoscale research of chemical engineering, linking established fundamentals with practical applications. Some critical issues and challenges regarding further development of this important functional material for nanotechnology will also be addressed. © 2011 Elsevier Ltd. All rights reserved.

  6. Extremely superhydrophobic surfaces with micro- and nanostructures fabricated by copper catalytic etching.

    Science.gov (United States)

    Lee, Jung-Pil; Choi, Sinho; Park, Soojin

    2011-01-18

    We demonstrate a simple method for the fabrication of rough silicon surfaces with micro- and nanostructures, which exhibited superhydrophobic behaviors. Hierarchically rough silicon surfaces were prepared by copper (Cu)-assisted chemical etching process where Cu nanoparticles having particle size of 10-30 nm were deposited on silicon surface, depending on the period of time of electroless Cu plating. Surface roughness was controlled by both the size of Cu nanoparticles and etching conditions. As-synthesized rough silicon surfaces showed water contact angles ranging from 93° to 149°. Moreover, the hierarchically rough silicon surfaces were chemically modified by spin-coating of a thin layer of Teflon precursor with low surface energy. And thus it exhibited nonsticky and enhanced hydrophobic properties with extremely high contact angle of nearly 180°.

  7. Black silicon laser-doped selective emitter solar cell with 18.1% efficiency

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Li, Hongzhao; To, Alexander

    2016-01-01

    We report fabrication of nanostructured, laser-doped selective emitter (LDSE) silicon solar cells with power conversion efficiency of 18.1% and a fill factor (FF) of 80.1%. The nanostructured solar cells were realized through a single step, mask-less, scalable reactive ion etch (RIE) texturing......-texturing as well as the LDSE process, we consider this specific combination a promising candidate for a cost-efficient process for future Si solar cells....

  8. Manganese Nanostructures and Magnetism

    Science.gov (United States)

    Simov, Kirie Rangelov

    The primary goal of this study is to incorporate adatoms with large magnetic moment, such as Mn, into two technologically significant group IV semiconductor (SC) matrices, e.g. Si and Ge. For the first time in the world, we experimentally demonstrate Mn doping by embedding nanostructured thin layers, i.e. delta-doping. The growth is observed by in-situ scanning tunneling microscopy (STM), which combines topographic and electronic information in a single image. We investigate the initial stages of Mn monolayer growth on a Si(100)(2x1) surface reconstruction, develop methods for classification of nanostructure types for a range of surface defect concentrations (1.0 to 18.2%), and subsequently encapsulate the thin Mn layer in a SC matrix. These experiments are instrumental in generating a surface processing diagram for self-assembly of monoatomic Mn-wires. The role of surface vacancies has also been studied by kinetic Monte Carlo modeling and the experimental observations are compared with the simulation results, leading to the conclusion that Si(100)(2x1) vacancies serve as nucleation centers in the Mn-Si system. Oxide formation, which happens readily in air, is detrimental to ferromagnetism and lessens the magnetic properties of the nanostructures. Therefore, the protective SC cap, composed of either Si or Ge, serves a dual purpose: it is both the embedding matrix for the Mn nanostructured thin film and a protective agent for oxidation. STM observations of partially deposited caps ensure that the nanostructures remain intact during growth. Lastly, the relationship between magnetism and nanostructure types is established by an in-depth study using x-ray magnetic circular dichroism (XMCD). This sensitive method detects signals even at coverages less than one atomic layer of Mn. XMCD is capable of discerning which chemical compounds contribute to the magnetic moment of the system, and provides a ratio between the orbital and spin contributions. Depending on the amount

  9. The silicon-silicon oxide multilayers utilization as intrinsic layer on pin solar cells

    International Nuclear Information System (INIS)

    Colder, H.; Marie, P.; Gourbilleau, F.

    2008-01-01

    Silicon nanostructures are promising candidate for the intrinsic layer on pin solar cells. In this work we report on new material: silicon-rich silicon oxide (SRSO) deposited by reactive magnetron sputtering of a pure silica target and an interesting structure: multilayers consisting of a stack of SRSO and pure silicon oxide layers. Two thicknesses of the SRSO sublayer, t SRSO , are studied 3 nm and 5 nm whereas the thickness of silica sublayer is maintaining at 3 nm. The presence of nanocrystallites of silicon, evidenced by X-Ray diffraction (XRD), leads to photoluminescence (PL) emission at room temperature due to the quantum confinement of the carriers. The PL peak shifts from 1.3 eV to 1.5 eV is correlated to the decreasing of t SRSO from 5 nm down to 3 nm. In the purpose of their potential utilization for i-layer, the optical properties are studied by absorption spectroscopy. The achievement a such structures at promising absorption properties. Moreover by favouring the carriers injection by the tunnel effect between silicon nanograins and silica sublayers, the multilayers seem to be interesting for solar cells

  10. Synthesis of ferroelectric nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Roervik, Per Martin

    2008-12-15

    The increasing miniaturization of electric and mechanical components makes the synthesis and assembly of nanoscale structures an important step in modern technology. Functional materials, such as the ferroelectric perovskites, are vital to the integration and utility value of nanotechnology in the future. In the present work, chemical methods to synthesize one-dimensional (1D) nanostructures of ferroelectric perovskites have been studied. To successfully and controllably make 1D nanostructures by chemical methods it is very important to understand the growth mechanism of these nanostructures, in order to design the structures for use in various applications. For the integration of 1D nanostructures into devices it is also very important to be able to make arrays and large-area designed structures from the building blocks that single nanostructures constitute. As functional materials, it is of course also vital to study the properties of the nanostructures. The characterization of properties of single nanostructures is challenging, but essential to the use of such structures. The aim of this work has been to synthesize high quality single-crystalline 1D nanostructures of ferroelectric perovskites with emphasis on PbTiO3 , to make arrays or hierarchical nanostructures of 1D nanostructures on substrates, to understand the growth mechanisms of the 1D nanostructures, and to investigate the ferroelectric and piezoelectric properties of the 1D nanostructures. In Paper I, a molten salt synthesis route, previously reported to yield BaTiO3 , PbTiO3 and Na2Ti6O13 nanorods, was re-examined in order to elucidate the role of volatile chlorides. A precursor mixture containing barium (or lead) and titanium was annealed in the presence of NaCl at 760 degrees Celsius or 820 degrees Celsius. The main products were respectively isometric nanocrystalline BaTiO3 and PbTiO3. Nanorods were also detected, but electron diffraction revealed that the composition of the nanorods was

  11. Silicon photonics III systems and applications

    CERN Document Server

    Lockwood, David

    2016-01-01

    This book is volume III of a series of books on silicon photonics. It reports on the development of fully integrated systems where many different photonics component are integrated together to build complex circuits. This is the demonstration of the fully potentiality of silicon photonics. It contains a number of chapters written by engineers and scientists of the main companies, research centers and universities active in the field. It can be of use for all those persons interested to know the potentialities and the recent applications of silicon photonics both in microelectronics, telecommunication and consumer electronics market.

  12. Electrochemical approach for monitoring the effect of anti tubulin drugs on breast cancer cells based on silicon nanograss electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Zanganeh, Somayeh; Khosravi, Safoora; Namdar, Naser; Amiri, Morteza Hassanpour; Gharooni, Milad [Nano Electronic Center of Excellence, Nano Bio Electronic Devices Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of); Nano Electronic Center of Excellence, Thin Film and Nanoelectronic Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of); Abdolahad, Mohammad, E-mail: m.abdolahad@ut.ac.ir [Nano Electronic Center of Excellence, Nano Bio Electronic Devices Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of); Nano Electronic Center of Excellence, Thin Film and Nanoelectronic Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of)

    2016-09-28

    One of the most interested molecular research in the field of cancer detection is the mechanism of drug effect on cancer cells. Translating molecular evidence into electrochemical profiles would open new opportunities in cancer research. In this manner, applying nanostructures with anomalous physical and chemical properties as well as biocompatibility would be a suitable choice for the cell based electrochemical sensing. Silicon based nanostructure are the most interested nanomaterials used in electrochemical biosensors because of their compatibility with electronic fabrication process and well engineering in size and electrical properties. Here we apply silicon nanograss (SiNG) probing electrodes produced by reactive ion etching (RIE) on silicon wafer to electrochemically diagnose the effect of anticancer drugs on breast tumor cells. Paclitaxel (PTX) and mebendazole (MBZ) drugs have been used as polymerizing and depolymerizing agents of microtubules. PTX would perturb the anodic/cathodic responses of the cell-covered biosensor by binding phosphate groups to deformed proteins due to extracellular signal-regulated kinase (ERK{sup 1/2}) pathway. MBZ induces accumulation of Cytochrome C in cytoplasm. Reduction of the mentioned agents in cytosol would change the ionic state of the cells monitored by silicon nanograss working electrodes (SiNGWEs). By extending the contacts with cancer cells, SiNGWEs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Effects of MBZ and PTX drugs, (with the concentrations of 2 nM and 0.1 nM, respectively) on electrochemical activity of MCF-7 cells are successfully recorded which are corroborated by confocal and flow cytometry assays. - Highlights: • Electrochemical effect of MBZ and PTX (anti tubulin drugs) on breast cancer cells was detected. • Detection was carried by silicon nanograss electrodes(SiNGEs). • Signaling pathways activated in the cells by drug treatment, change the

  13. Ductility of Nanostructured Bainite

    Directory of Open Access Journals (Sweden)

    Lucia Morales-Rivas

    2016-12-01

    Full Text Available Nanostructured bainite is a novel ultra-high-strength steel-concept under intensive current research, in which the optimization of its mechanical properties can only come from a clear understanding of the parameters that control its ductility. This work reviews first the nature of this composite-like material as a product of heat treatment conditions. Subsequently, the premises of ductility behavior are presented, taking as a reference related microstructures: conventional bainitic steels, and TRIP-aided steels. The ductility of nanostructured bainite is then discussed in terms of work-hardening and fracture mechanisms, leading to an analysis of the three-fold correlation between ductility, mechanically-induced martensitic transformation, and mechanical partitioning between the phases. Results suggest that a highly stable/hard retained austenite, with mechanical properties close to the matrix of bainitic ferrite, is advantageous in order to enhance ductility.

  14. Vortices and nanostructured superconductors

    CERN Document Server

    2017-01-01

    This book provides expert coverage of modern and novel aspects of the study of vortex matter, dynamics, and pinning in nanostructured and multi-component superconductors. Vortex matter in superconducting materials is a field of enormous beauty and intellectual challenge, which began with the theoretical prediction of vortices by A. Abrikosov (Nobel Laureate). Vortices, vortex dynamics, and pinning are key features in many of today’s human endeavors: from the huge superconducting accelerating magnets and detectors at the Large Hadron Collider at CERN, which opened new windows of knowledge on the universe, to the tiny superconducting transceivers using Rapid Single Flux Quanta, which have opened a revolutionary means of communication. In recent years, two new features have added to the intrinsic beauty and complexity of the subject: nanostructured/nanoengineered superconductors, and the discovery of a range of new materials showing multi-component (multi-gap) superconductivity. In this book, leading researche...

  15. Relaxation in magnetic nanostructures

    International Nuclear Information System (INIS)

    Novak, M.A.; Folly, W.S.D.; Sinnecker, J.P.; Soriano, S.

    2005-01-01

    Nanostructured magnetic materials present a wide range of magnetic relaxation phenomena. One problem in studying nanomagnetic granular materials is the strong dependence of the relaxation with the anisotropy barrier which, even for systems with narrow size distributions, brings difficulties in the analysis of the experimental data. Molecular magnetism, with the chemists' bottom-up approach to build molecular nanostructures, provides this field with some beautiful model systems, well ordered crystals of single molecule magnets, single molecule chains, molecular magnetic multilayers and others novelties to appear. Most of these systems present slow relaxation and the study of these well-characterized nanomaterials may elucidate many features that are difficult to grasp in the non molecular materials

  16. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

  17. Hybrid phonons in nanostructures

    CERN Document Server

    Ridley, Brian K

    2017-01-01

    Crystalline semiconductor nanostructures have special properties associated with electrons and lattice vibrations and their interaction, and this is the topic of the book. The result of spatial confinement of electrons is indicated in the nomenclature of nonostructures: quantum wells, quantum wires, and quantum dots. Confinement also has a profound effect on lattice vibrations and an account of this is the prime focus. The documentation of the confinement of acoustic modes goes back to Lord Rayleigh’s work in the late nineteenth century, but no such documentation exists for optical modes. Indeed, it is only comparatively recently that any theory of the elastic properties of optical modes exists, and the account given in the book is comprehensive. A model of the lattice dynamics of the diamond lattice is given that reveals the quantitative distinction between acoustic and optical modes and the difference of connection rules that must apply at an interface. The presence of interfaces in nanostructures forces ...

  18. Analysis of periodically patterned metallic nanostructures for infrared absorber

    Science.gov (United States)

    Peng, Sha; Yuan, Ying; Long, Huabao; Liu, Runhan; Wei, Dong; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

    2018-02-01

    With rapid advancement of infrared detecting technology in both military and civil domains, the photo-electronic performances of near-infrared detectors have been widely concerned. Currently, near-infrared detectors demonstrate some problems such as low sensitivity, low detectivity, and relatively small array scale. The current studies show that surface plasmons (SPs) stimulated over the surface of metallic nanostructures by incident light can be used to break the diffraction limit and thus concentrate light into sub-wavelength scale, so as to indicate a method to develop a new type of infrared absorber or detector with very large array. In this paper, we present the design and characterization of periodically patterned metallic nanostructures that combine nanometer thickness aluminum film with silicon wafer. Numerical computations show that there are some valleys caused by surface plasmons in the reflection spectrum in the infrared region, and both red shift and blue shift of the reflection spectrum were observed through changing the nanostructural parameters such as angle α and diameters D. Moreover, the strong E-field intensity is located at the sharp corner of the nano-structures.

  19. Plasmonic Nanostructured Cellular Automata

    Science.gov (United States)

    Alkhazraji, Emad; Ghalib, A.; Manzoor, K.; Alsunaidi, M. A.

    2017-03-01

    In this work, we have investigated the scattering plasmonic resonance characteristics of silver nanospheres with a geometrical distribution that is modelled by Cellular Automata using time-domain numerical analysis. Cellular Automata are discrete mathematical structures that model different natural phenomena. Two binary one-dimensional Cellular Automata rules are considered to model the nanostructure, namely rule 30 and rule 33. The analysis produces three-dimensional scattering profiles of the entire plasmonic nanostructure. For the Cellular Automaton rule 33, the introduction of more Cellular Automata generations resulted only in slight red and blue shifts in the plasmonic modes with respect to the first generation. On the other hand, while rule 30 introduced significant red shifts in the resonance peaks at early generations, at later generations however, a peculiar effect is witnessed in the scattering profile as new peaks emerge as a feature of the overall Cellular Automata structure rather than the sum of the smaller parts that compose it. We strongly believe that these features that emerge as a result adopting the different 256 Cellular Automata rules as configuration models of nanostructures in different applications and systems might possess a great potential in enhancing their capability, sensitivity, efficiency, and power utilization.

  20. Magnetic Properties of Large-Scale Nanostructured Graphene Systems

    DEFF Research Database (Denmark)

    Gregersen, Søren Schou

    The on-going progress in two-dimensional (2D) materials and nanostructure fabrication motivates the study of altered and combined materials. Graphene—the most studied material of the 2D family—displays unique electronic and spintronic properties. Exceptionally high electron mobilities, that surpass...... those in conventional materials such as silicon, make graphene a very interesting material for high-speed electronics. Simultaneously, long spin-diffusion lengths and spin-life times makes graphene an eligible spin-transport channel. In this thesis, we explore fundamental features of nanostructured...... graphene systems using large-scale modeling techniques. Graphene perforations, or antidots, have received substantial interest in the prospect of opening large band gaps in the otherwise gapless graphene. Motivated by recent improvements of fabrication processes, such as forming graphene antidots and layer...

  1. Silicone chain extender

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a silicone chain extender, more particularly a chain extender for silicone polymers and copolymers, to a chain extended silicone polymer or copolymer and to a functionalized chain extended silicone polymer or copolymer, to a method for the preparation thereof...

  2. Large area nanoscale patterning of silicon surfaces by parallel local oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Losilla, N S; Martinez, J; Garcia, R [Instituto de Microelectronica de Madrid, CSIC, Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain)

    2009-11-25

    The homogeneity and the reproducibility of parallel local oxidation have been improved by introducing a thin film of polymethylmethacrylate (PMMA) between the stamp and the silicon surface. The flexibility of the polymer film enables a homogeneous contact of the stamp with the silicon surface to be achieved. The oxides obtained yield better aspect ratios compared with the ones created with no PMMA layer. The pattern is formed when a bias voltage is applied between the stamp and the silicon surface for 1 min. The patterning can be done by a step and repeat technique and is reproducible across a centimetre length scale. Once the oxide nanostructures have been created, the polymer is removed by etching in acetone. Finally, parallel local oxidation is applied to fabricate silicon nanostructures and templates for the growth of organic molecules.

  3. Silicon plasmonics at midinfrared using silicon-insulator-silicon platform

    Science.gov (United States)

    Gamal, Rania; Shafaay, Sarah; Ismail, Yehea; Swillam, Mohamed A.

    2017-01-01

    We propose devices based on doped silicon. Doped silicon is designed to act as a plasmonic medium in the midinfrared (MIR) range. The surface plasmon frequency of the doped silicon can be tuned within the MIR range, which gives rise to useful properties in the material's dispersion. We propose various plasmonic configurations that can be utilized for silicon on-chip applications in MIR. These devices have superior performance over conventional silicon devices and provide unique functionalities such as 90-sharp degree bends, T- and X-junction splitters, and stubs. These devices are CMOS-compatible and can be easily integrated with other electronic devices. In addition, the potential for biological and environmental sensing using doped silicon nanowires is demonstrated.

  4. EDITORIAL: Excelling under strain: band engineering in nanomaterials Excelling under strain: band engineering in nanomaterials

    Science.gov (United States)

    Demming, Anna

    2013-08-01

    A little stress or strain has been known to improve the performance of athletes, actors and of course nanomaterials alike. In fact strain in silicon is now a major engineering tool for improving the performance of devices, and is ubiquitously used in device design and fabrication. Strain engineering alters a material's band structure, a model of electron behaviour that describes how as atoms come together in a solid, their discrete electron orbitals overlap to ultimately give rise to bands of allowed energy levels. In a strained crystal lattice of silicon or silicon germanium the distance between atoms in the lattice is greater than usual and the bands of allowed energy levels change. This July marks 100 years since Bohr submitted his paper 'On the constitution of atoms and molecules' [1] where he describes the structure of the atom in terms of discrete allowed energy levels. The paper was a seminal contribution to the development of quantum mechanics and laid the initial theoretical precepts for band gap engineering in devices. In this issue Nrauda and a collaboration of researchers in Europe and Australia study the growth of defect-free SiGe islands on pre-patterned silicon [2]. They analyse the strain in the islands and determine at what point lattice dislocations set in with a view to informing implementation of strain engineering in devices. The effects of strain on band structure in silicon and germanium were already studied and reported in the 1950s [3, 4]. Since then the increasing focus on nanoscale materials and the hunger for control of electronic properties has prompted further study of strain effects. The increased surface area to volume ratio in nanostructures changes the strain behaviour with respect to bulk materials, and this can also be exploited for handling and fine tuning strain to manipulate material properties. It is perhaps no surprise that graphene, one of the most high-profile materials in current nanotechnology research, has attracted

  5. Retrograde Melting and Internal Liquid Gettering in Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hudelson, Steve; Newman, Bonna K.; Bernardis, Sarah; Fenning, David P.; Bertoni, Mariana I.; Marcus, Matthew A.; Fakra, Sirine C.; Lai, Barry; Buonassisi, Tonio

    2011-07-01

    Retrograde melting (melting upon cooling) is observed in silicon doped with 3d transition metals, via synchrotron-based temperature-dependent X-ray microprobe measurements. Liquid metal-silicon droplets formed via retrograde melting act as efficient sinks for metal impurities dissolved within the silicon matrix. Cooling results in decomposition of the homogeneous liquid phase into solid multiple-metal alloy precipitates. These phenomena represent a novel pathway for engineering impurities in semiconductor-based systems.

  6. Simulations of Proton Implantation in Silicon Carbide (SiC)

    Science.gov (United States)

    2016-03-31

    Simulations of Proton Implantation in Silicon Carbide (SiC) Jonathan P. McCandless, Hailong Chen, Philip X.-L. Feng Electrical Engineering, Case...of implanting protons (hydrogen ions, H+) into SiC thin layers on silicon (Si) substrate, and explore the ion implantation conditions that are...relevant to experimental radiation of SiC layers. Keywords: silicon carbide (SiC); radiation effects; ion implantation; proton ; stopping and range of

  7. Plastic deformation of indium nanostructures

    International Nuclear Information System (INIS)

    Lee, Gyuhyon; Kim, Ju-Young; Burek, Michael J.; Greer, Julia R.; Tsui, Ting Y.

    2011-01-01

    Highlights: → Indium nanopillars display two different deformation mechanisms. → ∼80% exhibited low flow stresses near that of bulk indium. → Low strength nanopillars have strain rate sensitivity similar to bulk indium. → ∼20% of compressed indium nanopillars deformed at nearly theoretical strengths. → Low-strength samples do not exhibit strength size effects. - Abstract: Mechanical properties and morphology of cylindrical indium nanopillars, fabricated by electron beam lithography and electroplating, are characterized in uniaxial compression. Time-dependent deformation and influence of size on nanoscale indium mechanical properties were investigated. The results show two fundamentally different deformation mechanisms which govern plasticity in these indium nanostructures. We observed that the majority of indium nanopillars deform at engineering stresses near the bulk values (Type I), with a small fraction sustaining flow stresses approaching the theoretical limit for indium (Type II). The results also show the strain rate sensitivity and flow stresses in Type I indium nanopillars are similar to bulk indium with no apparent size effects.

  8. Crab shells as sustainable templates from nature for nanostructured battery electrodes.

    Science.gov (United States)

    Yao, Hongbin; Zheng, Guangyuan; Li, Weiyang; McDowell, Matthew T; Seh, Zhiwei; Liu, Nian; Lu, Zhenda; Cui, Yi

    2013-07-10

    Rational nanostructure design has been a promising route to address critical materials issues for enabling next-generation high capacity lithium ion batteries for portable electronics, vehicle electrification, and grid-scale storage. However, synthesis of functional nanostructures often involves expensive starting materials and elaborate processing, both of which present a challenge for successful implementation in low-cost applications. In seeking a sustainable and cost-effective route to prepare nanostructured battery electrode materials, we are inspired by the diversity of natural materials. Here, we show that crab shells with the unique Bouligand structure consisting of highly mineralized chitin-protein fibers can be used as biotemplates to fabricate hollow carbon nanofibers; these fibers can then be used to encapsulate sulfur and silicon to form cathodes and anodes for Li-ion batteries. The resulting nanostructured electrodes show high specific capacities (1230 mAh/g for sulfur and 3060 mAh/g for silicon) and excellent cycling performance (up to 200 cycles with 60% and 95% capacity retention, respectively). Since crab shells are readily available due to the 0.5 million tons produced annually as a byproduct of crab consumption, their use as a sustainable and low-cost nanotemplate represents an exciting direction for nanostructured battery materials.

  9. Thermally Induced Silane Dehydrocoupling on Silicon Nanostructures (International ed.)

    Science.gov (United States)

    2016-07-29

    of the antibiotic ciprofloxaxin (35% by mass). When intrinsically photoluminescent porous Si films or nanoparticles are used, photoluminescence is...reported the first grafting reaction of hydridosilanes with porous Si surfaces using early transition metal catalysts to effect the transformation.[3] The...work we find that the reaction proceeds under mild thermal conditions on pSi surfaces without any added catalyst to generate stable, functional

  10. Nanostructures induced light harvesting enhancement in organic photovoltaics

    Science.gov (United States)

    Bi, Yan-Gang; Feng, Jing; Ji, Jin-Hai; Yi, Fang-Shun; Li, Yun-Fei; Liu, Yue-Feng; Zhang, Xu-Lin; Sun, Hong-Bo

    2017-12-01

    Lightweight and low-cost organic photovoltaics (OPVs) hold great promise as renewable energy sources. The most critical challenge in developing high-performance OPVs is the incomplete photon absorption due to the low diffusion length of the carrier in organic semiconductors. To date, various attempts have been carried out to improve light absorption in thin photoactive layer based on optical engineering strategies. Nanostructure-induced light harvesting in OPVs offers an attractive solution to realize high-performance OPVs, via the effects of antireflection, plasmonic scattering, surface plasmon polarization, localized surface plasmon resonance and optical cavity. In this review article, we summarize recent advances in nanostructure-induced light harvesting in OPVs and discuss various light-trapping strategies by incorporating nanostructures in OPVs and the fabrication processing of the micro-patterns with high resolution, large area, high yield and low cost.

  11. Bottom-up silicon nanowire-based thermoelectric microgenerators

    Science.gov (United States)

    Dávila, D.; Huber, R.; Hierold, C.

    2015-12-01

    In this work, bottom-up intrinsic crystalline Si nanowire arrays in combination with top-down microfabrication techniques and a vertical device architecture have been proposed to develop an all-silicon nanostructured thermoelectric generator. To fabricate this device, a suitable vertical integration of Si NWs on patterned microstructures, which define the thermoelectric legs of the generator, has been achieved by bonding top and bottom silicon structures through nanowires. The process has been proven to be a feasible approach that employs a regrowth process of the nanowires for bonding purposes.

  12. Laser-induced incandescence from laser-heated silicon nanoparticles

    Science.gov (United States)

    Menser, Jan; Daun, Kyle; Dreier, Thomas; Schulz, Christof

    2016-11-01

    This work describes the application of temporally and spectrally resolved laser-induced incandescence to silicon nanoparticles synthesized in a microwave plasma reactor. Optical properties for bulk silicon presented in the literature were extended for nanostructured particles analyzed in this paper. Uncertainties of parameters in the evaporation submodel, as well as measurement noise, are incorporated into the inference process by Bayesian statistics. The inferred nanoparticle sizes agree with results from transmission electron microscopy, and the determined accommodation coefficient matches the values of the preceding study.

  13. Solar energy innovation and Silicon Valley

    Science.gov (United States)

    Kammen, Daniel M.

    2015-03-01

    The growth of the U. S. and global solar energy industry depends on a strong relationship between science and engineering innovation, manufacturing, and cycles of policy design and advancement. The mixture of the academic and industrial engine of innovation that is Silicon Valley, and the strong suite of environmental policies for which California is a leader work together to both drive the solar energy industry, and keep Silicon Valley competitive as China, Europe and other area of solar energy strength continue to build their clean energy sectors.

  14. Low temperature phonon boundary scattering in slightly rough Silicon nanowires

    Science.gov (United States)

    Ghossoub, Marc; Valavala, Krishna; Seong, Myunghoon; Azeredo, Bruno; Sadhu, Jyothi S.; Sinha, Sanjiv

    2013-03-01

    Nanostructured materials have lower thermal conductivities than the bulk and are promising candidates for thermoelectric applications. In particular, measurements on single silicon nanowires show a reduction in thermal conductivity below the Casimir limit. This reduction increases with surface roughness but the trend and its connection to phonon boundary scattering are still elusive. Here, we measure the thermal conductivity of single silicon nanowires fabricated using metal-assisted chemical etching. High resolution TEM imaging shows crystalline wires with slightly rough surfaces. Their statistical correlation lengths (5-15 nm) and RMS heights (0.8-1.5 nm) are in a range where perturbation-based wave scattering theory is still applicable. We use the thermal conductivity data to extract the frequency dependence of phonon boundary scattering at low temperatures (10-40 K) and show agreement with multiple scattering theory. This work provides insight into enhancing the thermoelectric performance of nanostructures.

  15. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  16. Semiconductors and semimetals nanostructured systems

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Reed, Mark A

    1992-01-01

    This is the first available volume to consolidate prominent topics in the emerging field of nanostructured systems. Recent technological advancements have led to a new era of nanostructure physics, allowing for the fabrication of nanostructures whose behavior is dominated by quantum interference effects. This new capability has enthused the experimentalist and theorist alike. Innumerable possibilities have now opened up for physical exploration and device technology on the nanoscale. This book, with contributions from five pioneering researchers, will allow the expert and novice alike to explore a fascinating new field.Provides a state-of-the-art review of quantum-scale artificially nanostructured electronic systemsIncludes contributions by world-known experts in the fieldOpens the field to the non-expert with a concise introductionFeatures discussions of:Low-dimensional condensed matter physicsProperties of nanostructured, ultrasmall electronic systemsMesoscopic physics and quantum transportPhysics of 2D ele...

  17. Graphene/silicon nanowire Schottky junction for enhanced light harvesting.

    Science.gov (United States)

    Fan, Guifeng; Zhu, Hongwei; Wang, Kunlin; Wei, Jinquan; Li, Xinming; Shu, Qinke; Guo, Ning; Wu, Dehai

    2011-03-01

    Schottky junction solar cells are assembled by directly coating graphene films on n-type silicon nanowire (SiNW) arrays. The graphene/SiNW junction shows enhanced light trapping and faster carrier transport compared to the graphene/planar Si structure. With chemical doping, the SiNW-based solar cells showed energy conversion efficiencies of up to 2.86% at AM1.5 condition, opening a possibility of using graphene/semiconductor nanostructures in photovoltaic application.

  18. Organosilane-functionalization of nanostructured indium tin oxide films.

    Science.gov (United States)

    Pruna, R; Palacio, F; Martínez, M; Blázquez, O; Hernández, S; Garrido, B; López, M

    2016-12-06

    Fabrication and organosilane-functionalization and characterization of nanostructured ITO electrodes are reported. Nanostructured ITO electrodes were obtained by electron beam evaporation, and a subsequent annealing treatment was selectively performed to modify their crystalline state. An increase in geometrical surface area in comparison with thin-film electrodes area was observed by atomic force microscopy, implying higher electroactive surface area for nanostructured ITO electrodes and thus higher detection levels. To investigate the increase in detectability, chemical organosilane-functionalization of nanostructured ITO electrodes was performed. The formation of 3-glycidoxypropyltrimethoxysilane (GOPTS) layers was detected by X-ray photoelectron spectroscopy. As an indirect method to confirm the presence of organosilane molecules on the ITO substrates, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were also carried out. Cyclic voltammograms of functionalized ITO electrodes presented lower reduction-oxidation peak currents compared with non-functionalized ITO electrodes. These results demonstrate the presence of the epoxysilane coating on the ITO surface. EIS showed that organosilane-functionalized electrodes present higher polarization resistance, acting as an electronic barrier for the electron transfer between the conductive solution and the ITO electrode. The results of these electrochemical measurements, together with the significant difference in the X-ray spectra between bare ITO and organosilane-functionalized ITO substrates, may point to a new exploitable oxide-based nanostructured material for biosensing applications. As a first step towards sensing, rapid functionalization of such substrates and their application to electrochemical analysis is tested in this work. Interestingly, oxide-based materials are highly integrable with the silicon chip technology, which would permit the easy adaptation of such sensors into lab

  19. Optical properties of quasiperiodically arranged semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Werchner, Marco

    2009-12-18

    This work consists of two parts which are entitled ''One-Dimensional Resonant Fibonacci Quasicrystals'' and ''Resonant Tunneling of Light in Silicon Nanostructures''. A microscopic theory has been applied to investigate the optical properties of the respective semiconductor nanostructures. The studied one-dimensional resonant Fibonacci quasicrystals consist of GaAs quantum wells (QW) that are separated by either a large spacer L or a small one S. These spacers are arranged according to the Fibonacci sequence LSLLSLSL.. The average spacing satisfies a generalized Bragg condition with respect to the 1s-exciton resonance of the QWs. A theory, that makes use of the transfer-matrix method and that allows for the microscopic description of many-body effects such as excitation-induced dephasing caused by the Coulomb scattering of carriers, has been applied to compute the optical spectra of such structures. A pronounced sharp reflectivity minimum is found in the vicinity of the heavy-hole resonance both in the measured as well as in the calculated linear 54-QW spectra. Specifically, the influence of the carrier density, of the QW arrangement, of a detuning away from the exact Bragg condition, of the average spacing as well as of the ratio of the optical path lengths of the large and small spacers L and S, respectively, and of the QW number on the optical properties of the samples have been studied. Additionally, self-similarity among reflection spectra corresponding to different QW numbers that exceed a Fibonacci number by one is observed, which identifies certain spectral features as true fingerprints of the Fibonacci spacing. In the second part, resonant tunneling of light in stacked structures consisting of alternating parallel layers of silicon and air have been studied theoretically.Light may tunnel through the air barrier due to the existence of evanescent waves inside the air layers if the neighboring silicon layer is close

  20. Robust Environmental Barrier Coatings for Silicon Nitride, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Silicon based ceramics are the leading candidates for the high temperature structural components of the advanced propulsion engines. For such applications, one key...

  1. Thermally induced nano-structural and optical changes of nc-Si:H deposited by hot-wire CVD

    CSIR Research Space (South Africa)

    Arendse, CJ

    2009-04-01

    Full Text Available This paper reports on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200–700 °C. The as-deposited sample has a high crystalline volume fraction of 53...

  2. Constructing metal-based structures on nanopatterned etched silicon.

    Science.gov (United States)

    Zhang, Xiaojiang; Qiao, Yinghong; Xu, Lina; Buriak, Jillian M

    2011-06-28

    Silicon surfaces with nanoscale etched patterns were obtained using polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer films as templates, followed by brief immersion in HF(aq). The resulting interfaces were comprised of pseudohexagonal arrays of pits on the silicon, whose shapes depended upon the chosen silicon orientation. The top unetched face of silicon remains capped by the native oxide, and the pit interiors are terminated by Si-H(x). Selective chemical functionalization via these two chemical handles was demonstrated to be a viable approach toward building nanostructured metal oxide and metal features within these silicon pits and on the top face. Using a series of interfacial chemical reactions, including oxidation (of Si-H(x)-terminated regions), hydrosilylation, and alkoxysilane-based chemistry on silicon oxide, the growth of metal-based structures can be spatially controlled. In the first approach, titania nanobowls were grown within the etch pits, and in the second, galvanic displacement was used to produce gold nanoparticles either within the etch pits, on the top silicon face, or both.

  3. Preparation of electrochemically active silicon nanotubes in highly ordered arrays

    Directory of Open Access Journals (Sweden)

    Tobias Grünzel

    2013-10-01

    Full Text Available Silicon as the negative electrode material of lithium ion batteries has a very large capacity, the exploitation of which is impeded by the volume changes taking place upon electrochemical cycling. A Si electrode displaying a controlled porosity could circumvent the difficulty. In this perspective, we present a preparative method that yields ordered arrays of electrochemically competent silicon nanotubes. The method is based on the atomic layer deposition of silicon dioxide onto the pore walls of an anodic alumina template, followed by a thermal reduction with lithium vapor. This thermal reduction is quantitative, homogeneous over macroscopic samples, and it yields amorphous silicon and lithium oxide, at the exclusion of any lithium silicides. The reaction is characterized by spectroscopic ellipsometry for thin silica films, and by nuclear magnetic resonance and X-ray photoelectron spectroscopy for nanoporous samples. After removal of the lithium oxide byproduct, the silicon nanotubes can be contacted electrically. In a lithium ion electrolyte, they then display the electrochemical waves also observed for other bulk or nanostructured silicon systems. The method established here paves the way for systematic investigations of how the electrochemical properties (capacity, charge/discharge rates, cyclability of nanoporous silicon negative lithium ion battery electrode materials depend on the geometry.

  4. Multi-diameter silicon nanowires: Fabrication, characterization, and modeling

    Science.gov (United States)

    Alagoz, Arif Sinan

    Nanotechnology is a rapidly expanding interdisciplinary field offering novel devices for broad range of applications. Quantum effects and surface to volume ratio of nanostructures are strongly size dependent, and redefine material properties at nanoscale. Silicon is one of the most promising materials for next generation nanostructured transistors, photonics devices, Li-ion batteries, photovoltaic solar cells, and thermoelectric energy generators. Since electrical, optical, and mechanical properties of nanostructures strongly depend on their shape, size, periodicity, and crystal structure; it is crucial to control these parameters in order to optimize device performance for targeted applications. This dissertation is intended to develop a low-cost, low-temperature, high-throughput, and large-area nanowire fabrication method that can produce well-ordered arrays of hierarchical single-crystal silicon nanowires at large scale by using nanosphere lithography and metal-assisted chemical etching. Nanowire morphology was characterized by using scanning electron microscope and optical properties of nanowire arrays were modeled with the help of finite-difference-time domain method. These novel multi-diameter silicon nanowire arrays have the potential applications in many fields including but not limited to next generation nanowire solar cells to field ionization gas sensors.

  5. Silicon Micro- and Nanofabrication for Medicine

    Science.gov (United States)

    Fine, Daniel; Goodall, Randy; Bansal, Shyam S.; Chiappini, Ciro; Hosali, Sharath; van de Ven, Anne L.; Srinivasan, Srimeenkashi; Liu, Xuewu; Godin, Biana; Brousseau, Louis; Yazdi, Iman K.; Fernandez-Moure, Joseph; Tasciotti, Ennio; Wu, Hung-Jen; Hu, Ye; Klemm, Steve; Ferrari, Mauro

    2013-01-01

    This manuscript constitutes a review of several innovative biomedical technologies fabricated using the precision and accuracy of silicon micro- and nanofabrication. The technologies to be reviewed are subcutaneous nanochannel drug delivery implants for the continuous tunable zero-order release of therapeutics, multi-stage logic embedded vectors for the targeted systemic distribution of both therapeutic and imaging contrast agents, silicon and porous silicon nanowires for investigating cellular interactions and processes as well as for molecular and drug delivery applications, porous silicon (pSi) as inclusions into biocomposites for tissue engineering, especially as it applies to bone repair and regrowth, and porous silica chips for proteomic profiling. In the case of the biocomposites, the specifically designed pSi inclusions not only add to the structural robustness, but can also promote tissue and bone regrowth, fight infection, and reduce pain by releasing stimulating factors and other therapeutic agents stored within their porous network. The common material thread throughout all of these constructs, silicon and its associated dielectrics (silicon dioxide, silicon nitride, etc.), can be precisely and accurately machined using the same scalable micro- and nanofabrication protocols that are ubiquitous within the semiconductor industry. These techniques lend themselves to the high throughput production of exquisitely defined and monodispersed nanoscale features that should eliminate architectural randomness as a source of experimental variation thereby potentially leading to more rapid clinical translation. PMID:23584841

  6. Structure tailored properties and functionalities of zero-dimensional nanostructures

    Science.gov (United States)

    Tang, Yun

    The field of nanoscience and nanotechnology has achieved significant progress over last thirty years. Complex nanostructures with tunable properties for novel applications have been successfully fabricated and characterized. In this thesis, I will focus on our recent efforts on precise controlled synthesis of zero-dimensional nanostructures as well as fundamental understanding of the physical behavior of assynthesized nanostructures. Particularly, three topics are presented: (1) Nanoscale crystallinity engineering: we have achieved nanoscale crystallinity control of noble metal nanoparticles with 100% yield by molecular engineering. We have used silver nanoparticles as example to demonstrate synthetic strategy and importance of such control in nanoscale chemical transformation, fundamental electron and phonon couplings and surface plasmon resonance based biological sensors. Such nanoscale crystallinity engineering provides a new pathway for design of complex nanostructures, tailoring nanoscale electronic and mechanical properties as well as controlling classical and quantum coupling interactions; (2) Precise control of core shell nanostructures: we have developed a new universal strategy denoted as intermediated phase assisted phase exchange and reaction (iPAPER) to achieve layer-by-layer control of shell components in core shell structures. Tunable plasmonic, optical and magnetic properties of core shell structures enabled by our iPAPER strategy are further demonstrated. These characterizations are promising for understanding and manipulating nanoscale phenomena as well as assembling nanoscale devices with desirable functionality; and (3) Fundamental spin and structure manipulation of semiconductor quantum dots by hydrostatic pressure. Pressure provides a unique means of modifying materials properties. By measuring dependence of spin dynamics on pressure, we revealed that the spin states of semiconductor quantum dots are very robust. We further provided the first

  7. Irradiation-Induced Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Birtcher, R.C.; Ewing, R.C.; Matzke, Hj.; Meldrum, A.; Newcomer, P.P.; Wang, L.M.; Wang, S.X.; Weber, W.J.

    1999-08-09

    This paper summarizes the results of the studies of the irradiation-induced formation of nanostructures, where the injected interstitials from the source of irradiation are not major components of the nanophase. This phenomena has been observed by in situ transmission electron microscopy (TEM) in a number of intermetallic compounds and ceramics during high-energy electron or ion irradiations when the ions completely penetrate through the specimen. Beginning with single crystals, electron or ion irradiation in a certain temperature range may result in nanostructures composed of amorphous domains and nanocrystals with either the original composition and crystal structure or new nanophases formed by decomposition of the target material. The phenomenon has also been observed in natural materials which have suffered irradiation from the decay of constituent radioactive elements and in nuclear reactor fuels which have been irradiated by fission neutrons and other fission products. The mechanisms involved in the process of this nanophase formation are discussed in terms of the evolution of displacement cascades, radiation-induced defect accumulation, radiation-induced segregation and phase decomposition, as well as the competition between irradiation-induced amorphization and recrystallization.

  8. Methods of Si based ceramic components volatilization control in a gas turbine engine

    Science.gov (United States)

    Garcia-Crespo, Andres Jose; Delvaux, John; Dion Ouellet, Noemie

    2016-09-06

    A method of controlling volatilization of silicon based components in a gas turbine engine includes measuring, estimating and/or predicting a variable related to operation of the gas turbine engine; correlating the variable to determine an amount of silicon to control volatilization of the silicon based components in the gas turbine engine; and injecting silicon into the gas turbine engine to control volatilization of the silicon based components. A gas turbine with a compressor, combustion system, turbine section and silicon injection system may be controlled by a controller that implements the control method.

  9. Electrical engineer's reference book

    CERN Document Server

    Laughton, M A

    1985-01-01

    Electrical Engineer's Reference Book, Fourteenth Edition focuses on electrical engineering. The book first discusses units, mathematics, and physical quantities, including the international unit system, physical properties, and electricity. The text also looks at network and control systems analysis. The book examines materials used in electrical engineering. Topics include conducting materials, superconductors, silicon, insulating materials, electrical steels, and soft irons and relay steels. The text underscores electrical metrology and instrumentation, steam-generating plants, turbines

  10. Silicon Based Anodes for Li-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiguang; Wang, Wei; Xiao, Jie; Xu, Wu; Graff, Gordon L.; Yang, Zhenguo; Choi, Daiwon; Li, Xiaolin; Wang, Deyu; Liu, Jun

    2012-06-15

    Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has been conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the

  11. Growth and characterization of nanostructured CuO films via CBD approach for oxygen gas sensing

    Science.gov (United States)

    Nurfazliana, M. F.; Sahdan, M. Z.; Saim, H.

    2017-01-01

    Nanostructured copper oxide (CuO) films were grown on portable IDE circuit silicon-based by low-cost chemical bath deposition (CBD) technique at three different deposition times (3 h, 5 h and 7 h). The effect of deposition times on the morphological, structural, optical and sensing properties of the nanostructured films were investigated. From the morphological and structural properties, the nanostructured film deposited at 5 h was found to have homogenous surface of CuO nanowhiskers and high crystallinity with tenorite phase compared to 3 h and 7 h films. Besides, there is no heat treatment required in order to produce CuO nanostructures film with tenorite phase. The sensing response (resistance changes) of as-synthesized films to concentration of oxygen (O2) gas also was compared. Film resistance of CuO nanostructures was studied in an environment of dry air loaded (gas sensor chamber) with 30 % of O2 gas. The results revealed that the deposition time causes significant effect on the sensing performance of nanostructured CuO to O2 gas.

  12. Exciton Resonances in Novel Silicon Carbide Polymers

    Science.gov (United States)

    Burggraf, Larry; Duan, Xiaofeng

    2015-05-01

    A revolutionary technology transformation from electronics to excitionics for faster signal processing and computing will be advantaged by coherent exciton transfer at room temperature. The key feature required of exciton components for this technology is efficient and coherent transfer of long-lived excitons. We report theoretical investigations of optical properties of SiC materials having potential for high-temperature excitonics. Using Car-Parinello simulated annealing and DFT we identified low-energy SiC molecular structures. The closo-Si12C12 isomer, the most stable 12-12 isomer below 1100 C, has potential to make self-assembled chains and 2-D nanostructures to construct exciton components. Using TDDFT, we calculated the optical properties of the isomer as well as oligomers and 2-D crystal formed from the isomer as the monomer unit. This molecule has large optical oscillator strength in the visible. Its high-energy and low-energy transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer. These results are useful to describe resonant, coherent transfer of dark excitons in the nanostructures. Research supported by the Air Force Office of Scientific Research.

  13. Low Temperature Growth of Nanostructured Diamond Films on Metals

    Science.gov (United States)

    Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

    2001-01-01

    The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments

  14. Fabrication of nanowires and nanostructures

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Piraux, L.

    2009-01-01

    We report on different approaches that we have adopted and developed for the fabrication of nanowires and nanostructures. Methods based on template synthesis and on self organization seem to be the most promising for the fabrication of nanomaterials and nanostructures due to their easiness and low...... cost. The development of a supported nanoporous alumina template and the possibility of using this template to combine electrochemical synthesis with lithographic methods open new ways for the fabrication of complex nanostructures. The numerous advantages of the supported template and its compatibility...

  15. Mechanical design of DNA nanostructures.

    Science.gov (United States)

    Castro, Carlos E; Su, Hai-Jun; Marras, Alexander E; Zhou, Lifeng; Johnson, Joshua

    2015-04-14

    Structural DNA nanotechnology is a rapidly emerging field that has demonstrated great potential for applications such as single molecule sensing, drug delivery, and templating molecular components. As the applications of DNA nanotechnology expand, a consideration of their mechanical behavior is becoming essential to understand how these structures will respond to physical interactions. This review considers three major avenues of recent progress in this area: (1) measuring and designing mechanical properties of DNA nanostructures, (2) designing complex nanostructures based on imposed mechanical stresses, and (3) designing and controlling structurally dynamic nanostructures. This work has laid the foundation for mechanically active nanomachines that can generate, transmit, and respond to physical cues in molecular systems.

  16. A model study of surface state on optical bandgap of silicon nanowires

    African Journals Online (AJOL)

    It is observed that visible PL in silicon nanowires is due to quantum confinement and surface passivation. But the energy recombination of electron and holes in the quantum confined nanostructures is responsible for the visible PL. In this work, models from quantum bandgap and photoluminescence intensity are adopted to ...

  17. Sub-15nm Silicon Lines Fabrication via PS-b-PDMS Block Copolymer Lithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu

    2013-01-01

    -b-PDMS (33 k–17 k) was conditioned by applying solvent and solvothermal annealing techniques. BCP nanopatterns formed after the annealing process have been confirmed by scanning electron microscope (SEM) after removal of upper PDMS wetting layer by plasma etching. Silicon nanostructures were obtained...

  18. Cell motility, morphology, viability and proliferation in response to nanotopography on silicon black.

    NARCIS (Netherlands)

    Łopacińska, Joanna M; Grǎdinaru, Cristian; Wierzbicki, Rafal; Købler, Carsten; Schmidt, Michael S; Madsen, Martin T; Skolimowski, Maciej; Dufva, Martin; Flyvbjerg, Henrik; Mølhave, Kristian

    2012-01-01

    Knowledge of cells' interactions with nanostructured materials is fundamental for bio-nanotechnology. We present results for how individual mouse fibroblasts from cell line NIH3T3 respond to highly spiked surfaces of silicon black that were fabricated by maskless reactive ion etching (RIE). We did

  19. Broadband antireflection silicon carbide surface by self-assembled nanopatterned reactive-ion etching

    DEFF Research Database (Denmark)

    Ou, Yiyu; Aijaz, Imran; Jokubavicius, Valdas

    2013-01-01

    of 390x02013;784 nm is dramatically suppressed from 21.0x00025; to 1.9x00025; after introducing the pseudoperiodic nanostructures. A luminescence enhancement of 226x00025; was achieved at an emission angle of 20x000B0; on the fluorescent silicon carbide. Meanwhile, the angle-resolved photoluminescence...... study presents a considerable omnidirectional luminescence enhancement....

  20. Photonic and plasmonic guided modes in graphene-silicon photonic crystals

    DEFF Research Database (Denmark)

    Gu, Tingyi; Andryieuski, Andrei; Hao, Yufeng

    2016-01-01

    We report the results of systematic studies of plasmonic and photonic guided modes in large-area single-layer graphene integrated into a nanostructured silicon substrate. The interaction of light with graphene and substrate photonic crystals can be classified in distinct regimes of plasmonic...

  1. Photonic and Plasmonic Guided Modes in Graphene-Silicon Photonic Crystals

    DEFF Research Database (Denmark)

    Gu, Tingyi; Andryieuski, Andrei; Hao, Yufeng

    2015-01-01

    We report the results of systematic studies of plasmonic and photonic guided modes in large-area single-layer graphene integrated into a nanostructured silicon substrate. The interaction of light with graphene and substrate photonic crystals can be classified in distinct regimes depending...

  2. Synthesis of silicon oxide microropes on the copper substrate with SiO2 interlayer

    Science.gov (United States)

    Baranov, E.; Khmel, S.; Zamchiy, A.; Shatskiy, E.

    2017-11-01

    Nanostructuring of the surface is a promising technology for the processes of boiling. In this paper, we synthesized array of “microropes” from silicon oxide nanowires on the copper substrate with a silicon oxide intermediate layer by gas-jet electron beam plasma CVD method. The morphology for the synthesis time of 2 minutes 30 seconds and 5 minutes was obtained. The water droplet on the silicon oxide nanowires shows the measured contact angles 14° and 10° for deposition times of 5 min and 2 min 30 sec, respectively.

  3. Plasma texturing on large-area industrial grade CZ silicon solar cells

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Nordseth, Ørnulf; Schmidt, Michael Stenbæk

    2013-01-01

    We report on an experimental study of nanostructuring of silicon solar cells using reactive ion etching (RIE). A simple mask-less, scalable RIE nanostructuring of the solar cell surface is shown to reduce the AM1.5-weighted average reflectance to a level below 1 % in a fully optimized RIE texturing......, and thus holds a significant potential for improvement of the cell performance compared to current industrial standards. The reflectance is shown to remain below that of conventional textured cells also at high angle of incidence. The process is shown to be equally applicable to mono-, multi- and quasi......-mono-crystalline Si. The process was successfully integrated in fabrication of solar cells using only industry standard processes on a Czochralski (CZ) silicon starting material. The resulting cell performance was compared to cells with conventional texturing. For cells, where the nanostructuring was not fully...

  4. Plasma texturing on large-area industrial grade CZ silicon solar cells

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Nordseth, Ørnulf; Boisen, Anja

    2013-01-01

    We report on an experimental study of nanostructuring of silicon solar cells using reactive ion etching (RIE). A simple mask-less, scalable RIE nanostructuring of the solar cell surface is shown to reduce the AM1.5-weighted average reflectance to a level below 1 % in a fully optimized RIE texturing......-mono-crystalline Si. The process was successfully integrated in fabrication of solar cells using only industry standard processes on a Czochralski (CZ) silicon starting material. The resulting cell performance was compared to cells with conventional texturing. For cells, where the nanostructuring was not fully......, and thus holds a significant potential for improvement of the cell performance compared to current industrial standards. The reflectance is shown to remain below that of conventional textured cells also at high angle of incidence. The process is shown to be equally applicable to mono-, multi- and quasi...

  5. Ab initio prediction of nano-structured materials using supercomputer

    International Nuclear Information System (INIS)

    Kumar, V.; Kawazoe, Y.

    2003-01-01

    Full text: Nano-structured materials are currently attracting great attention due to their promise in future nano-technologies. In the scale of a nanometer, properties of matter are sensitive to the atomic details that are often difficult to obtain from experiments. Impurities could change the properties very significantly. Predictive computer simulations based on ab initio methods are playing a very important role in not only supporting and explaining the experimental findings but also suggesting new possibilities. We shall present a brief overview of the current research done in our group using the supercomputing facilities of the IMR in designing and predicting nano-structured materials. These include the areas of molecular electronics, carbon fullerenes and nanotubes, super-structures on surfaces, multilayers, clusters and nanowires using calculational approaches such as all electron mixed basis, augmented plane wave, localized basis and pseudopotential plane wave methods. More accurate descriptions based on GW and QMC methods are also used. The possibilities of doing large scale calculations are also allowing the study of biological systems such as DNA. We shall discuss in more detail our recent predictions of novel metal encapsulated silicon fullerenes and nanotubes that offer new possibilities in developing silicon based technologies at the nano-scale

  6. Nanostructured epoxi networks

    International Nuclear Information System (INIS)

    Soares, Bluma G.; Silva, Adriana A.; Sollymossy, Ana Paula F.; Dahmouche, Karim

    2011-01-01

    Nanostructured epoxy materials including nanocomposites were obtained by incorporating different organic or inorganic systems. Epoxy networks containing rubber particles with nanometric size have been obtained by an appropriate functionalization of the elastomers, in order to improve the interfacial adhesion between rubber and epoxy matrix. This adhesion also conferred an improvement of the impact resistance and thermal properties. This work also presents some results related to the utilization of inorganic nanoparticles in epoxy systems, including organo clay or hybrid materials based on functionalized silsesquioxanes. The nanoscopic characterization of these materials were performed by small angle X-ray scattering (SAXS) combined with transmission electron microscopy (TEM). The effect of dispersion degree of the inorganic nanoparticles on the rheological properties was also investigated. (author)

  7. @AuAg nanostructures

    Science.gov (United States)

    Singh, Rina; Soni, R. K.

    2014-09-01

    Bimetallic and trimetallic nanoparticles have attracted significant attention in recent times due to their enhanced electrochemical and catalytic properties compared to monometallic nanoparticles. The numerical calculations using Mie theory has been carried out for three-layered metal nanoshell dielectric-metal-metal (DMM) system consisting of a particle with a dielectric core (Al@Al2O3), a middle metal Ag (Au) layer and an outer metal Au (Ag) shell. The results have been interpreted using plasmon hybridization theory. We have also prepared Al@Al2O3@Ag@Au and Al@Al2O3@AgAu triple-layered core-shell or alloy nanostructure by two-step laser ablation method and compared with calculated results. The synthesis involves temporal separations of Al, Ag, and Au deposition for step-by-step formation of triple-layered core-shell structure. To form Al@Ag nanoparticles, we ablated silver for 40 min in aluminium nanoparticle colloidal solution. As aluminium oxidizes easily in water to form alumina, the resulting structure is core-shell Al@Al2O3. The Al@Al2O3 particle acts as a seed for the incoming energetic silver particles for multilayered Al@Al2O3@Ag nanoparticles is formed. The silver target was then replaced by gold target and ablation was carried out for different ablation time using different laser energy for generation of Al@Al2O3@Ag@Au core-shell or Al@Al2O3@AgAu alloy. The formation of core-shell and alloy nanostructure was confirmed by UV-visible spectroscopy. The absorption spectra show shift in plasmon resonance peak of silver to gold in the range 400-520 nm with increasing ablation time suggesting formation of Ag-Au alloy in the presence of alumina particles in the solution.

  8. Silicon: electrochemistry and luminescence

    NARCIS (Netherlands)

    Kooij, Ernst Stefan

    1997-01-01

    The electrochemistry of crystalline and porous silicon and the luminescence from porous silicon has been studied. One chapter deals with a model for the anodic dissolution of silicon in HF solution. In following chapters both the electrochemistry and various ways of generating visible

  9. Concurrent design of quasi-random photonic nanostructures

    Science.gov (United States)

    Lee, Won-Kyu; Yu, Shuangcheng; Engel, Clifford J.; Reese, Thaddeus; Rhee, Dongjoon; Chen, Wei; Odom, Teri W.

    2017-08-01

    Nanostructured surfaces with quasi-random geometries can manipulate light over broadband wavelengths and wide ranges of angles. Optimization and realization of stochastic patterns have typically relied on serial, direct-write fabrication methods combined with real-space design. However, this approach is not suitable for customizable features or scalable nanomanufacturing. Moreover, trial-and-error processing cannot guarantee fabrication feasibility because processing-structure relations are not included in conventional designs. Here, we report wrinkle lithography integrated with concurrent design to produce quasi-random nanostructures in amorphous silicon at wafer scales that achieved over 160% light absorption enhancement from 800 to 1,200 nm. The quasi-periodicity of patterns, materials filling ratio, and feature depths could be independently controlled. We statistically represented the quasi-random patterns by Fourier spectral density functions (SDFs) that could bridge the processing-structure and structure-performance relations. Iterative search of the optimal structure via the SDF representation enabled concurrent design of nanostructures and processing.

  10. Sliding wear of conventional and nanostructured cemented carbides

    Energy Technology Data Exchange (ETDEWEB)

    Jia, K. [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering; Fischer, T.E. [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering

    1997-03-01

    The sliding wear mechanisms of cemented carbide and the effects of the microstructure scale on the wear resistance were investigated by performing a series of unlubricated sliding wear tests in air with pins of WC-Co composites sliding against silicon nitride disks. In the first approximation, the wear rate is proportional to the hardness with a wear coefficient k=6.9x10{sup -6} for all materials. In the conventional cermets, the wear coefficient k also depends on the grain size; materials with smaller WC grains exhibit a smaller wear resistance. This reduction, however, does not extend to the nanostructured materials which exhibit the above value for k: Their wear resistance is higher than that of conventional cermets in proportion to their hardness. The data can also be expressed in terms of cobalt content: The lower the cobalt content, the lower the wear; but two different such dependencies exist, one for the conventional and one for the nanostructured materials with lower wear. The sliding wear of WC-Co composites occurs on a very small scale: The worn surfaces show no evidence of fracture of plastic deformation. This wear behavior is explained by the hexagonal structure and the anisotropic mechanical behavior of the WC grains that are capable of shear in a limited number of planes but are not capable of triaxial deformation. The higher wear resistance of the nanostructured composites is related to their hardness which decreases the real area of contact. (orig.)

  11. Nanostructured Photovoltaics for Space Power

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA NSTRF proposal entitled Nanostructured Photovoltaics for Space Power is targeted towards research to improve the current state of the art photovoltaic...

  12. Quantum optics with semiconductor nanostructures

    CERN Document Server

    Jahnke, Frank

    2012-01-01

    A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...

  13. Nanostructured surfaces for anti-biofouling/anti-microbial applications

    Science.gov (United States)

    Choi, Chang-Hwan; Kim, Chang-Jin

    2009-05-01

    Recent nanotechnology revolutions have cast increased challenges to biotechnology including bio-adhesion of cells. Surface topography and chemistry tailored by the nanotechnology exert significant effects on such applications so that it is necessary to understand how cells migrate and adhere on three-dimensional micro- and nanostructures. However, the effects of the surface topography and chemistry on cell adhesions have not been studied systematically and interactively yet mostly due to the inability to create well-controlled nanostructures over a relatively large surface area. In this paper, we report on the bio-adhesions of varying cell types on well-ordered (post and grate patterns), dense-array (230 nm in pattern periodicity), and sharp-tip (less than 10 nm in tip radius) nanostructures with varying three-dimensionalities (50- 500 nm in structural height). Significantly lower cell proliferation and smaller cell size were measured on tall nanostructures. On a grate pattern, significant cell elongation and alignment along the grate pattern were observed. On tall nanostructures, it was shown that cells were levitated by sharp tips and easily peeled off, suggesting that cell adherence to the tall and sharp-tip nanostructures was relatively weak. The control of cell growth and adherence by the nanoscale surface topographies can benefit the micro- and nanotechnogies-based materials, devices, and systems, such as for anti-biofouling and anti-microbial surfaces. The obtained knowledge by this investigation will also be useful to deal with engineering problems associated with the contact with biological substances such as biomaterials and biosensors.

  14. Potential applications of nanostructured materials in nuclear waste management.

    Energy Technology Data Exchange (ETDEWEB)

    Braterman, Paul S. (The University of North Texas, Denton, TX); Phol, Phillip Isabio; Xu, Zhi-Ping (The University of North Texas, Denton, TX); Brinker, C. Jeffrey; Yang, Yi (University of New Mexico, Albuquerque, NM); Bryan, Charles R.; Yu, Kui; Xu, Huifang (University of New Mexico, Albuquerque, NM); Wang, Yifeng; Gao, Huizhen

    2003-09-01

    This report summarizes the results obtained from a Laboratory Directed Research & Development (LDRD) project entitled 'Investigation of Potential Applications of Self-Assembled Nanostructured Materials in Nuclear Waste Management'. The objectives of this project are to (1) provide a mechanistic understanding of the control of nanometer-scale structures on the ion sorption capability of materials and (2) develop appropriate engineering approaches to improving material properties based on such an understanding.

  15. Bioinspired periodic pinecone-shaped Si subwavelength nanostructures for broadband and omnidirectional antireflective surface.

    Science.gov (United States)

    Leem, Jung Woo; Yu, Jae Su

    2012-10-01

    We reported the bioinspired periodic pinecone-shaped silicon (Si) subwavelength nanostructures, which were fabricated by laser interference lithography and inductively coupled plasma etching using thermally dewetted gold (Au) nanoparticles in SiCl4 plasma, on Si substrates for broadband and wide-angle antireflective surface. For the fabricated pinecone-like Si subwavelength nanostructures, antireflection characteristics and wetting behaviors were investigated. The pinecone-shaped Si subwavelength nanostructure with a period of 320 nm for 7 nm of Au film exhibited a relatively low solar weighted reflectance value of 3.5% over a wide wavelength range of 300-1030 nm, maintaining the reflectance values of < 9.9% at a wavelength of 550 nm up to a high incident angle of theta(i) = 70 degrees for non-polarized light. This structure also showed a hydrophobic surface with a water contact angle of theta(c) approximately 102 degrees.

  16. Proposal of a Failure Criterion of Adhesively Bonded Connections with Silicone

    OpenAIRE

    Staudt, Yves Nico Louis

    2017-01-01

    In the field of façade engineering, structural silicone sealants have been used in adhesively bonded connections since the 1960s. The low strength and stiffness of silicone rubber compared to other types of adhesives are compensated by the excellent adhesion properties and the good resistance against ageing and environmental influences, like UV radiation. Silicone sealants show a pronounced nonlinear material behaviour. The applicable design concepts in civil engineering propose simplified de...

  17. Synthesis of vertically aligned metal oxide nanostructures

    KAUST Repository

    Roqan, Iman S.

    2016-03-03

    Metal oxide nanostructure and methods of making metal oxide nanostructures are provided. The metal oxide nanostructures can be 1 -dimensional nanostructures such as nanowires, nanofibers, or nanotubes. The metal oxide nanostructures can be doped or undoped metal oxides. The metal oxide nanostructures can be deposited onto a variety of substrates. The deposition can be performed without high pressures and without the need for seed catalysts on the substrate. The deposition can be performed by laser ablation of a target including a metal oxide and, optionally, a dopant. In some embodiments zinc oxide nanostructures are deposited onto a substrate by pulsed laser deposition of a zinc oxide target using an excimer laser emitting UV radiation. The zinc oxide nanostructure can be doped with a rare earth metal such as gadolinium. The metal oxide nanostructures can be used in many devices including light-emitting diodes and solar cells.

  18. Nanoparticle production in arc generated fireballs of granular silicon powder

    Science.gov (United States)

    Ito, Tsuyohito; Cappelli, Mark A.

    2012-03-01

    Recently we observed buoyant fireballs by arc igniting silicon that drift in air for several seconds and postulated that the low aggregate density was attributed to the formation of a network of nanoparticles that must completely surround the burning silicon core, trapping the heated vapor generated as a result of particle combustion [Ito et al. Phys Rev E 80, 067401 (2009)]. In this paper, we describe the capturing of several of these fireballs in flight, and have characterized their nanostructure by high resolution microscopy. The nanoparticle network is found to have an unusually high porosity (> 99%), suggesting that this arc-ignition of silicon can be a novel method of producing ultra-porous silica. While we confirm the presence of a nanoparticle network within the fireballs, the extension of this mechanism to the production of ball lightning during atmospheric lightning strikes in nature is still the subject of ongoing debate.

  19. Nanoparticle production in arc generated fireballs of granular silicon powder

    Directory of Open Access Journals (Sweden)

    Tsuyohito Ito

    2012-03-01

    Full Text Available Recently we observed buoyant fireballs by arc igniting silicon that drift in air for several seconds and postulated that the low aggregate density was attributed to the formation of a network of nanoparticles that must completely surround the burning silicon core, trapping the heated vapor generated as a result of particle combustion [Ito et al. Phys Rev E 80, 067401 (2009]. In this paper, we describe the capturing of several of these fireballs in flight, and have characterized their nanostructure by high resolution microscopy. The nanoparticle network is found to have an unusually high porosity (> 99%, suggesting that this arc-ignition of silicon can be a novel method of producing ultra-porous silica. While we confirm the presence of a nanoparticle network within the fireballs, the extension of this mechanism to the production of ball lightning during atmospheric lightning strikes in nature is still the subject of ongoing debate.

  20. Thermal conductivity of silicon nanocrystals and polystyrene nanocomposite thin films

    International Nuclear Information System (INIS)

    Juangsa, Firman Bagja; Muroya, Yoshiki; Nozaki, Tomohiro; Ryu, Meguya; Morikawa, Junko

    2016-01-01

    Silicon nanocrystals (SiNCs) are well known for their size-dependent optical and electronic properties; they also have the potential for low yet controllable thermal properties. As a silicon-based low-thermal conductivity material is required in microdevice applications, SiNCs can be utilized for thermal insulation. In this paper, SiNCs and polymer nanocomposites were produced, and their thermal conductivity, including the density and specific heat, was measured. Measurement results were compared with thermal conductivity models for composite materials, and the comparison shows a decreasing value of the thermal conductivity, indicating the effect of the size and presence of the nanostructure on the thermal conductivity. Moreover, employing silicon inks at room temperature during the fabrication process enables a low cost of fabrication and preserves the unique properties of SiNCs. (paper)

  1. Fabrication of 3D nano-structures using reverse imprint lithography

    International Nuclear Information System (INIS)

    Han, Kang-Soo; Cho, Joong-Yeon; Lee, Heon; Hong, Sung-Hoon; Kim, Kang-In; Choi, Kyung-woo

    2013-01-01

    In spite of the fact that the fabrication process of three-dimensional nano-structures is complicated and expensive, it can be applied to a range of devices to increase their efficiency and sensitivity. Simple and inexpensive fabrication of three-dimensional nano-structures is necessary. In this study, reverse imprint lithography (RIL) with UV-curable benzylmethacrylate, methacryloxypropyl terminated poly-dimethylsiloxane (M-PDMS) resin and ZnO-nano-particle-dispersed resin was used to fabricate three-dimensional nano-structures. UV-curable resins were placed between a silicon stamp and a PVA transfer template, followed by a UV curing process. Then, the silicon stamp was detached and a 2D pattern layer was transferred to the substrate using diluted UV-curable glue. Consequently, three-dimensional nano-structures were formed by stacking the two-dimensional nano-patterned layers. RIL was applied to a light-emitting diode (LED) to evaluate the optical effects of a nano-patterned layer. As a result, the light extraction of the patterned LED was increased by about 12% compared to an unpatterned LED. (paper)

  2. Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

    KAUST Repository

    Hussain, Muhammad Mustafa

    2013-05-30

    Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  3. Effects of pore design on mechanical properties of nanoporous silicon

    International Nuclear Information System (INIS)

    Winter, Nicholas; Becton, Matthew; Zhang, Liuyang; Wang, Xianqiao

    2017-01-01

    Nanoporous silicon has been emerging as a powerful building block for next-generation sensors, catalysts, transistors, and tissue scaffolds. The capability to design novel devices with desired mechanical properties is paramount to their reliability and serviceability. In order to bring further resolution to the highly variable mechanical characteristics of nanoporous silicon, here we perform molecular dynamics simulations to study the effects of ligament thickness, relative density, and pore geometry/orientation on the mechanical properties of nanoporous silicon, thereby determining its Young's modulus, ultimate strength, and toughness as well as the scaling laws versus the features of interior ligaments. Results show that pore shape and pattern dictate stress accumulation inside the designed structure, leading to the corresponding failure signature, such as stretching-dominated, bending-dominated, or stochastic failure signatures, in nanoporous silicon. The nanostructure of the material is also seen to drive or mute size effects such as “smaller is stronger” and “smaller is ductile”. This investigation provides useful insight into the behavior of nanoporous silicon and how one might leverage its promising applications. - Graphical abstract: Molecular dynamics simulations are performed to study the effects of ligament thickness, relative density, and pore geometry/orientation on the mechanical properties of nanoporous silicon, thereby determining its Young's modulus, ultimate strength, and toughness as well as the scaling trends versus the features of interior ligaments.

  4. Ga+ beam lithography for nanoscale silicon reactive ion etching

    Science.gov (United States)

    Henry, M. D.; Shearn, M. J.; Chhim, B.; Scherer, A.

    2010-06-01

    By using a dry etch chemistry which relies on the highly preferential etching of silicon, over that of gallium (Ga), we show resist-free fabrication of precision, high aspect ratio nanostructures and microstructures in silicon using a focused ion beam (FIB) and an inductively coupled plasma reactive ion etcher (ICP-RIE). Silicon etch masks are patterned via Ga + ion implantation in a FIB and then anisotropically etched in an ICP-RIE using fluorinated etch chemistries. We determine the critical areal density of the implanted Ga layer in silicon required to achieve a desired etch depth for both a Pseudo Bosch (SF6/C4F8) and cryogenic fluorine (SF6/O2) silicon etching. High fidelity nanoscale structures down to 30 nm and high aspect ratio structures of 17:1 are demonstrated. Since etch masks may be patterned on uneven surfaces, we utilize this lithography to create multilayer structures in silicon. The linear selectivity versus implanted Ga density enables grayscale lithography. Limits on the ultimate resolution and selectivity of Ga lithography are also discussed.

  5. Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Diroll, Benjamin T. [Center; Schramke, Katelyn S. [Department; Guo, Peijun [Center; Kortshagen, Uwe R. [Department; Schaller, Richard D. [Center; Department

    2017-09-15

    Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

  6. Sampling Artifacts from Conductive Silicone Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse; Jayne, John T.; Worsnop, Douglas R.; Miake-Lye, Richard C.; Onasch, Timothy B.; Liscinsky, David; Kirchstetter, Thomas W.; Destaillats, Hugo; Holder, Amara L.; Smith, Jared D.; Wilson, Kevin R.

    2009-05-15

    We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosol mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the particle surface area increases. The effect is observed at ambient temperature and enhanced by mild heating (<100 oC). Further evaluation is warranted.

  7. Obtaining porous silicon suitable for sensor technology using MacEtch nonelectrolytic etching

    Directory of Open Access Journals (Sweden)

    Iatsunskyi I. R.

    2013-12-01

    Full Text Available The author suggests to use the etching method MacEtch (metal-assisted chemical etching for production of micro- and nanostructures of porous silicon. The paper presents research results on the morphology structures obtained at different parameters of deposition and etching processes. The research has shown that, depending on the parameters of deposition of silver particles and silicon wafers etching, the obtained surface morphology may be different. There may be both individual crater-like pores and developed porous or macroporous surface. These results indicate that the MacEtch etching is a promising method for obtaining micro-porous silicon nanostructures suitable for effective use in gas sensors and biological object sensors.

  8. Highly efficient silicon solar cells designed with photon trapping micro/nano structures

    Science.gov (United States)

    Bartolo-Perez, Cesar; Gao, Yang; Cansizoglu, Hilal; Ghandiparsi, Soroush; Kaya, Ahmet; Mayet, Ahmed; Ponizovskaya Devine, Ekaterina; Yamada, Toshishige; Elrefaie, Aly; Wang, Shih-Yuan; Islam, M. Saif

    2017-08-01

    Crystalline silicon (c-Si) remains the most commonly used material for photovoltaic (PV) cells in the current commercial solar cells market. However, current technology requires "thick" silicon due to the relative weak absorption of Si in the solar spectrum. We demonstrate several CMOS compatible fabrication techniques including dry etch, wet etch and their combination to create different photon trapping micro/nanostructures on very thin c-silicon surface for light harvesting of PVs. Both, the simulation and experimental results show that these photon trapping structures are responsible for the enhancement of the visible light absorption which leads to improved efficiency of the PVs. Different designs of micro/nanostructures via different fabrication techniques are correlated with the efficiencies of the PVs. Our method can also drastically reduce the thickness of the c-Si PVs, and has great potential to reduce the cost, and lead to highly efficient and flexible PVs.

  9. Electrical and thermal conductivities of the graphene, boron nitride and silicon boron honeycomb monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.com [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Khodadadi, Jabbar [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Moradi Kurdestany, Jamshid [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65201 (United States); Yarmohammadi, Zahra [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of)

    2016-11-25

    Density of states, electrical and thermal conductivities of electrons in graphene, boron nitride and silicon boron single sheets are studied within the tight-binding Hamiltonian model and Green's function formalism, based on the linear response theory. The results show that while boron nitride keeps significantly the lowest amounts overall with an interval of zero value in low temperatures, due to its insulating nature, graphene exhibits the most electrical and thermal conductivities, slightly higher than silicon boron except for low temperature region where the latter surpasses, owing to its metallic character. This work might make ideas for creating new electronic devices based on honeycomb nanostructures. - Highlights: • Electronic properties of graphene, silicon boron, and boron nitride planes are compared. • Tight-binding Hamiltonian model and Green's function formalism are implemented. • This work might make ideas for creating new electronic devices based on honeycomb nanostructures.

  10. Optical properties of plasmonic nanostructures: Theory & experiments

    Science.gov (United States)

    Bala Krishna, Juluri

    Metal nanoparticles and thin films enable localization of electromagnetic energy in the form of localized surface plasmon resonances (LSPR) and propagating surface plasmons respectively. This research field, also known as plasmonics, involves understanding and fabricating innovative nanostructures designed to manage and utilize localized light in the nanoscale. Advances in plasmonics will facilitate innovation in sensing, biomedical engineering, energy harvesting and nanophotonic devices. In this thesis, three aspects of plasmonics are studied: 1) active plasmonic systems using charge-induced plasmon shifts (CIPS) and plasmon-molecule resonant coupling; 2) scalable solutions to fabricate large electric field plasmonic nanostructures; and 3) controlling the propagation of designer surface plasmons (DSPs) using parabolic graded media. The full potential of plasmonics can be realized with active plasmonic devices which provide tunable plasmon resonances. The work reported here develops both an understanding for and realization of various mechanisms to achieve tunable plasmonic systems. First, we show that certain nanoparticle geometries and material compositions enable large CIPS. Second, we propose and investigate systems which exhibit coupling between molecular and plasmonic resonances where energy splitting is observed due to interactions between plasmons and molecules. Large electric field nanostructures have many promising applications in the areas of surface enhanced Raman spectroscopy, higher harmonic light generation, and enhanced uorescence. High throughput techniques that utilize simple nanofabrication are essential their advancement. We contribute to this effort by using a salting-out quenching technique and colloidal lithography to fabricate nanodisc dimers and cusp nanostructures that allow localization of large electric fields, and are comparable to structures fabricated by conventional lithography/milling techniques. Designer surface plasmons (DSPs) are

  11. Ultra-high speed all-optical signal processing using silicon waveguides and a carbon nanotubes based mode-locked laser

    DEFF Research Database (Denmark)

    Ji, Hua

    for demultiplexing of 1.28 Tbit/s optical time division multiplexing data signal is investigated. A sampling system for ultra-high speed signal waveforms based on nano-engineered silicon waveguide is explored. To set up a sampling source, using carbon nanotubes for generating ultra-short pulses is pursued. A silicon......This thesis concerns the use of nano-engineered silicon waveguides for ultra-high speed optical serial data signal processing. The fundamental nonlinear properties of nano-engineered silicon waveguides are characterized. Utilizing the nonlinear effect in nano-engineered silicon waveguides...

  12. Oxide driven strength evolution of silicon surfaces

    Science.gov (United States)

    Grutzik, Scott J.; Milosevic, Erik; Boyce, Brad L.; Zehnder, Alan T.

    2015-11-01

    Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation.

  13. Nanostructural characterization of amorphous diamondlike carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, M. P. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Tallant, D. R. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Martinez-Miranda, L. J. [University of Maryland, Department of Materials and Nuclear Engineering, College Park, Maryland 20742 (United States); Barbour, J. C. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Simpson, R. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Overmyer, D. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2000-04-15

    Nanostructural characterization of amorphous diamondlike carbon (a-C) films grown on silicon using pulsed-laser deposition (PLD) is correlated to both growth energetics and film thickness. Raman spectroscopy and x-ray reflectivity probe both the topological nature of three- and four-fold coordinated carbon atom bonding and the topographical clustering of their distributions within a given film. In general, increasing the energetics of PLD growth results in films becoming more ''diamondlike,'' i.e., increasing mass density and decreasing optical absorbance. However, these same properties decrease appreciably with thickness. The topology of carbon atom bonding is different for material near the substrate interface compared to material within the bulk portion of an a-C film. A simple model balancing the energy of residual stress and the free energies of resulting carbon topologies is proposed to provide an explanation of the evolution of topographical bonding clusters in a growing a-C film. (c) 2000 The American Physical Society.

  14. Asymmetric wettability of nanostructures directs leidenfrost droplets.

    Science.gov (United States)

    Agapov, Rebecca L; Boreyko, Jonathan B; Briggs, Dayrl P; Srijanto, Bernadeta R; Retterer, Scott T; Collier, C Patrick; Lavrik, Nickolay V

    2014-01-28

    Leidenfrost phenomena on nano- and microstructured surfaces are of great importance for increasing control over heat transfer in high power density systems utilizing boiling phenomena. They also provide an elegant means to direct droplet motion in a variety of recently emerging fluidic systems. Here, we report the fabrication and characterization of tilted nanopillar arrays (TNPAs) that exhibit directional Leidenfrost water droplets under dynamic conditions, namely on impact with Weber numbers ≥40 at T ≥ 325 °C. The directionality for these droplets is opposite to the direction previously exhibited by macro- and microscale Leidenfrost ratchets where movement against the tilt of the ratchet was observed. The batch fabrication of the TNPAs was achieved by glancing-angle anisotropic reactive ion etching of a thermally dewet platinum mask, with mean pillar diameters of 100 nm and heights of 200-500 nm. In contrast to previously implemented macro- and microscopic Leidenfrost ratchets, our TNPAs induce no preferential directional movement of Leidenfrost droplets under conditions approaching steady-state film boiling, suggesting that the observed droplet directionality is not a result of the widely accepted mechanism of asymmetric vapor flow. Using high-speed imaging, phase diagrams were constructed for the boiling behavior upon impact for droplets falling onto TNPAs, straight nanopillar arrays, and smooth silicon surfaces. The asymmetric impact and directional trajectory of droplets was exclusive to the TNPAs for impacts corresponding to the transition boiling regime, linking asymmetric surface wettability to preferential directionality of dynamic Leidenfrost droplets on nanostructured surfaces.

  15. Periodic titania nanostructures using block copolymer templates.

    Science.gov (United States)

    Chinthamanipeta, Pavan S; Lou, Qin; Shipp, Devon A

    2011-01-25

    The deposition of periodic titania nanostructures, templated by a polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer, is reported. When cast as a thin film (30-50 nm thick), the PS-b-P4VP forms a morphology that consists of P4VP cylinders that are orientated perpendicular to the substrate. The P4VP phase was lightly cross-linked by exposing the film to diiodobutane. When the block copolymer film was exposed to the sol-gel titania precursor, titanium(IV) bis(ammonium lactate) dihydroxide (TALH), titania was formed in the P4VP phase. The resulting titania structures were identical in size to the P4VP cylinders and only formed (under the deposition conditions used in this study) when the block copolymer film was present on the substrate, thus providing evidence that the block copolymer indeed acts as a template. The process works for both silicon and indium tin oxide substrates.

  16. Uni-directional liquid spreading on asymmetric nanostructured surfaces

    Science.gov (United States)

    Chu, Kuang-Han; Xiao, Rong; Wang, Evelyn N.

    2010-05-01

    Controlling surface wettability and liquid spreading on patterned surfaces is of significant interest for a broad range of applications, including DNA microarrays, digital lab-on-a-chip, anti-fogging and fog-harvesting, inkjet printing and thin-film lubrication. Advancements in surface engineering, with the fabrication of various micro/nanoscale topographic features, and selective chemical patterning on surfaces, have enhanced surface wettability and enabled control of the liquid film thickness and final wetted shape. In addition, groove geometries and patterned surface chemistries have produced anisotropic wetting, where contact-angle variations in different directions resulted in elongated droplet shapes. In all of these studies, however, the wetting behaviour preserves left-right symmetry. Here, we demonstrate that we can harness the design of asymmetric nanostructured surfaces to achieve uni-directional liquid spreading, where the liquid propagates in a single preferred direction and pins in all others. Through experiments and modelling, we determined that the spreading characteristic is dependent on the degree of nanostructure asymmetry, the height-to-spacing ratio of the nanostructures and the intrinsic contact angle. The theory, based on an energy argument, provides excellent agreement with experimental data. The insights gained from this work offer new opportunities to tailor advanced nanostructures to achieve active control of complex flow patterns and wetting on demand.

  17. Nanostructured Pluronic hydrogels as bioinks for 3D bioprinting

    International Nuclear Information System (INIS)

    Müller, Michael; Zenobi-Wong, Marcy; Becher, Jana; Schnabelrauch, Matthias

    2015-01-01

    Bioprinting is an emerging technology in the field of tissue engineering as it allows the precise positioning of biologically relevant materials in 3D, which more resembles the native tissue in our body than current homogenous, bulk approaches. There is however a lack of materials to be used with this technology and materials such as the block copolymer Pluronic have good printing properties but do not allow long-term cell culture. Here we present an approach called nanostructuring to increase the biocompatibility of Pluronic gels at printable concentrations. By mixing acrylated with unmodified Pluronic F127 it was possible to maintain the excellent printing properties of Pluronic and to create stable gels via UV crosslinking. By subsequent elution of the unmodified Pluronic from the crosslinked network we were able to increase the cell viability of encapsulated chondrocytes at day 14 from 62% for a pure acrylated Pluronic hydrogel to 86% for a nanostructured hydrogel. The mixed Pluronic gels also showed good printability when cells where included in the bioink. The nanostructured gels were, with a compressive modulus of 1.42 kPa, mechanically weak, but we were able to increase the mechanical properties by the addition of methacrylated hyaluronic acid. Our nanostructuring approach enables Pluronic hydrogels to have the desired set of properties in all stages of the bioprinting process. (paper)

  18. Thermal Diffusivity of SPS Pressed Silicon Powders and the Potential for Using Bottom-Up Silicon Quantum Dots as a Starting Material

    Science.gov (United States)

    Ashby, Shane P.; Bian, Tiezheng; Ning, Huanpo; Reece, Michael J.; Chao, Yimin

    2015-06-01

    The production of nanostructured bulk materials from silicon powders has been well documented as being one way of bringing down the thermal conductivity of silicon while still maintaining its high power factor. This reduction of thermal conductivity is predicted to lead to significant increases in its figure-of-merit, ZT. The size of the starting particles has a major effect on the nanostructuring and grain size of the final silicon-based materials. Using particles of differing size and distribution, pellets were produced using spark plasma sintering. The results show a significant lowering in the thermal diffusivity as the particle size in the powders is decreased. As the starting particle size deceases from 1 μm to 60 nm, we see a tenfold decrease in the thermal diffusivity at 300 K, from 20 mm2 S-1 to 2 mm2 S-1. Both these show a significant decrease from the thermal diffusivity of 88 mm2 S-1 observed from bulk silicon. A further decrease to 1 mm2 S-1 is observed when the particle size of the starting material is decreased from 60 nm to sub-10 nm. The results also highlight the potential of using particles from solution approaches as a potential starting point for the prediction of nanostructured bulk materials.

  19. Periodic nanostructures self-formed on silicon and silicon carbide by femtosecond laser irradiation

    Czech Academy of Sciences Publication Activity Database

    Gemini, Laura; Hashida, M.; Shimizu, M.; Miyasaka, Y.; Inoue, S.; Tokita, S.; Limpouch, J.; Mocek, Tomáš; Sakabe, S.

    2014-01-01

    Roč. 117, č. 1 (2014), s. 49-54 ISSN 0947-8396 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143; GA MŠk(CZ) LG13029 Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : coulomb explosion * ablation * surfaces * metals * pulses * semiconductors * fabrication * thresholds * picosecond Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.704, year: 2014

  20. Optical, electrical and structural properties of nanostructured silicon and silicon-germanium alloys

    CERN Document Server

    Uenal, B

    1998-01-01

    epitaxy (SS-MBE). These PL investigations were carried out to determine the difference in decay times between PS and PSG. The EXAFS was used to characterise structural properties before and after anodisation of Si wafers and MBE-SiGe on Si. Additionally, the oxygen environment in PSG networks was investigated to obtain a deeper understanding of the visible emission mechanisms of porous materials. EL from [metal /PS/Si] structures based on n-type ultraviolet-PS (UV-PS) exhibits a wider FWHM than for PL of about 200nm, peaked at 635nm, emitted beneath the semi-transparent gold film. A reversible avalanche breakdown was observed at the metal-PS interface at a certain reverse bias. Mechanisms for the observed I-V and EL spectral response are suggested. Photovoltaic effects from PS-based devices fabricated with anodisation are also presented. The effect of a laser beam illumination on the photosensitivity was characterised. The I-V characteristics of several n- and p-type PS based PV devices have been measured und...