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Sample records for nanostructures including nanowires

  1. Analytic device including nanostructures

    Di Fabrizio, Enzo M.; Fratalocchi, Andrea; Totero Gongora, Juan Sebastian; Coluccio, Maria Laura; Candeloro, Patrizio; Cuda, Gianni

    2015-01-01

    A device for detecting an analyte in a sample comprising: an array including a plurality of pixels, each pixel including a nanochain comprising: a first nanostructure, a second nanostructure, and a third nanostructure, wherein size of the first nanostructure is larger than that of the second nanostructure, and size of the second nanostructure is larger than that of the third nanostructure, and wherein the first nanostructure, the second nanostructure, and the third nanostructure are positioned on a substrate such that when the nanochain is excited by an energy, an optical field between the second nanostructure and the third nanostructure is stronger than an optical field between the first nanostructure and the second nanostructure, wherein the array is configured to receive a sample; and a detector arranged to collect spectral data from a plurality of pixels of the array.

  2. Fabrication of nanowires and nanostructures

    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...

  3. Methods of fabricating nanostructures and nanowires and devices fabricated therefrom

    Majumdar, Arun; Shakouri, Ali; Sands, Timothy D.; Yang, Peidong; Mao, Samuel S.; Russo, Richard E.; Feick, Henning; Weber, Eicke R.; Kind, Hannes; Huang, Michael; Yan, Haoquan; Wu, Yiying; Fan, Rong

    2018-01-30

    One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as "nanowires", include single-crystalline homostructures as well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN).

  4. Nanowires and nanostructures fabrication using template methods

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Vlad, A.

    2009-01-01

    One of the great challenges of today is to find reliable techniques for the fabrication of nanomaterials and nanostructures. Methods based on template synthesis and on self organization are the most promising due to their easiness and low cost. This paper focuses on the electrochemical synthesis ...... of nanowires and nanostructures using nanoporous host materials such as supported anodic aluminum considering it as a key template for nanowires based devices. New ways are opened for applications by combining such template synthesis methods with nanolithographic techniques....

  5. Templated electrodeposition of functional nanostructures: nanowires, nanotubes and nanocubes

    Maijenburg, A.W.

    2014-01-01

    This thesis is entitled “Templated electrodeposition of functional nanostructures: nanowires, nanotubes and nanocubes”. Templated electrodeposition is the synthesis technique that was used throughout this thesis, and it comprises the use of a template with specific shape and dimensions for the formation of different types of nanostructures. Throughout this thesis, three different nanostructures were made: nanowires (Chapters 2 to 6), nanotubes (Chapters 2 and 5) and nanocubes (Chapters 7 and ...

  6. Templated electrodeposition of functional nanostructures: nanowires, nanotubes and nanocubes

    Maijenburg, A.W.

    2014-01-01

    This thesis is entitled “Templated electrodeposition of functional nanostructures: nanowires, nanotubes and nanocubes”. Templated electrodeposition is the synthesis technique that was used throughout this thesis, and it comprises the use of a template with specific shape and dimensions for the

  7. Design and fabrication of Ni nanowires having periodically hollow nanostructures.

    Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2014-10-07

    We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag 'barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 ± 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni(2+) for the interior surfaces of AAO. The Ni shell layer allows the Ni segments to remain even after dissolution of the Ag segments. Because the electroplating conditions can be easily controlled, we could carefully adjust the size and pitch of the periodically hollow nanospaces. We also describe a method for the fabrication of Ni nanorods by forming an Ag shell instead of a Ni shell on the Ni-Ag barcode nanowire, in which the interior of the AAO surfaces was modified with a compound bearing a thiol group prior to electroplating.

  8. Design and fabrication of Ni nanowires having periodically hollow nanostructures

    Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2014-09-01

    We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag `barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 +/- 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni2+ for the interior surfaces of AAO. The Ni shell layer allows the Ni segments to remain even after dissolution of the Ag segments. Because the electroplating conditions can be easily controlled, we could carefully adjust the size and pitch of the periodically hollow nanospaces. We also describe a method for the fabrication of Ni nanorods by forming an Ag shell instead of a Ni shell on the Ni-Ag barcode nanowire, in which the interior of the AAO surfaces was modified with a compound bearing a thiol group prior to electroplating.We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag `barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 +/- 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni2+ for the

  9. Self-bridging of vertical silicon nanowires and a universal capacitive force model for spontaneous attraction in nanostructures.

    Sun, Zhelin; Wang, Deli; Xiang, Jie

    2014-11-25

    Spontaneous attractions between free-standing nanostructures have often caused adhesion or stiction that affects a wide range of nanoscale devices, particularly nano/microelectromechanical systems. Previous understandings of the attraction mechanisms have included capillary force, van der Waals/Casimir forces, and surface polar charges. However, none of these mechanisms universally applies to simple semiconductor structures such as silicon nanowire arrays that often exhibit bunching or adhesions. Here we propose a simple capacitive force model to quantitatively study the universal spontaneous attraction that often causes stiction among semiconductor or metallic nanostructures such as vertical nanowire arrays with inevitably nonuniform size variations due to fabrication. When nanostructures are uniform in size, they share the same substrate potential. The presence of slight size differences will break the symmetry in the capacitive network formed between the nanowires, substrate, and their environment, giving rise to electrostatic attraction forces due to the relative potential difference between neighboring wires. Our model is experimentally verified using arrays of vertical silicon nanowire pairs with varied spacing, diameter, and size differences. Threshold nanowire spacing, diameter, or size difference between the nearest neighbors has been identified beyond which the nanowires start to exhibit spontaneous attraction that leads to bridging when electrostatic forces overcome elastic restoration forces. This work illustrates a universal understanding of spontaneous attraction that will impact the design, fabrication, and reliable operation of nanoscale devices and systems.

  10. Fabrication of nanostructure via self-assembly of nanowires within the AAO template

    Brust Mathias

    2006-01-01

    Full Text Available AbstractThe novel nanostructures are fabricated by the spatial chemical modification of nanowires within the anodic aluminum oxide (AAO template. To make the nanowires better dispersion in the aqueous solution, the copper is first deposited to fill the dendrite structure at the bottom of template. During the process of self-assembly, the dithiol compound was used as the connector between the nanowires and nanoparticles by a self-assembly method. The nanostructures of the nano cigars and structure which is containing particles junction are characterized by transmission electron microscopy (TEM. These kinds of novel nanostructure will be the building blocks for nanoelectronic and nanophotonic devices.

  11. Electrochemical synthesis and characterization of hierarchically branched ZnO nanostructures on ensembles of gold nanowires

    Ongaro, Michael; Gambirasi, Arianna; Favaro, Monica; Ugo, Paolo

    2012-01-01

    Highlights: ► ZnO branched nanofibres for photoelectrochemical applications. ► Branched nanostructures are obtained by electrochemical deposition of ZnO on gold template nanowires. ► Branched nanowires crystallographic phase determined by electron back scatter diffraction. ► Branched structures display improved performances for the photoelectrochemical oxidation of water. - Abstract: This study presents an electrosynthetic methodology to obtain hierarchically structured ZnO electrodes with improved surface area, by exploiting gold nanowires ensembles (3D-NEEs) as the growing substrate. By this way, semiconductor electrodes organized in the shape of fir-like branches are obtained. Branched nanofibres are characterized by electron microscopy and electron backscatter diffraction (EBSD), the latter technique allowing the determination of the crystalline habit of individual nanostructures. The hierarchical branched nanowires show enhanced performances with respect to water photooxidation in comparison with already known nanostructured materials such as 1D-ZnO nanowires.

  12. Vibration of Piezoelectric Nanowires Including Surface Effects

    R. Ansari

    2014-04-01

    Full Text Available In this paper, surface and piezoelectric effects on the vibration behavior of nanowires (NWs are investigated by using a Timoshenko beam model. The electric field equations and the governing equations of motion for the piezoelectric NWs are derived with the consideration of surface effects. By the exact solution of the governing equations, an expression for the natural frequencies of NWs with simply-supported boundary conditions is obtained. The effects of piezoelectricity and surface effects on the vibrational behavior of Timoshenko NWs are graphically illustrated. A comparison is also made between the predictions of Timoshenko beam model and those of its Euler-Bernoulli counterpart. Additionally, the present results are validated through comparison with the available data in the literature.

  13. Modulation of fluorescence signals from biomolecules along nanowires due to interaction of light with oriented nanostructures

    Frederiksen, Rune Schøneberg; Alarcon-Llado, Esther; Madsen, Morten H.

    2015-01-01

    High aspect ratio nanostructures have gained increasing interest as highly sensitive platforms for biosensing. Here, well-defined biofunctionalized vertical indium arsenide nanowires are used to map the interaction of light with nanowires depending on their orientation and the excitation waveleng...

  14. Photovoltaic Performance of a Nanowire/Quantum Dot Hybrid Nanostructure Array Solar Cell.

    Wu, Yao; Yan, Xin; Zhang, Xia; Ren, Xiaomin

    2018-02-23

    An innovative solar cell based on a nanowire/quantum dot hybrid nanostructure array is designed and analyzed. By growing multilayer InAs quantum dots on the sidewalls of GaAs nanowires, not only the absorption spectrum of GaAs nanowires is extended by quantum dots but also the light absorption of quantum dots is dramatically enhanced due to the light-trapping effect of the nanowire array. By incorporating five layers of InAs quantum dots into a 500-nm high-GaAs nanowire array, the power conversion efficiency enhancement induced by the quantum dots is six times higher than the power conversion efficiency enhancement in thin-film solar cells which contain the same amount of quantum dots, indicating that the nanowire array structure can benefit the photovoltaic performance of quantum dot solar cells.

  15. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad; Rafii-Tabar, Hashem

    2014-05-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin-Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  16. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad; Rafii-Tabar, Hashem

    2014-01-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin–Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  17. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    Ghavanloo, Esmaeal, E-mail: ghavanloo@shirazu.ac.ir [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of); Fazelzadeh, S. Ahmad [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of); Rafii-Tabar, Hashem [Department of Medical Physics and Biomedical Engineering, Research Center for Medical Nanotechnology and Tissue Engineering, Shahid Beheshti University of Medical Sciences, Evin, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, School of Nano-Science, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of)

    2014-05-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin–Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  18. The mechanism of transforming diamond nanowires to carbon nanostructures

    Sorkin, Anastassia; Su, Haibin

    2014-01-01

    The transformation of diamond nanowires (DNWs) with different diameters and geometries upon heating is investigated with density-functional-based tight-binding molecular dynamics. DNWs of 〈100〉 and 〈111〉 oriented cross-section with projected average line density between 7 and 20 atoms Å −1 transform into carbon nanotubes (CNTs) under gradual heating up to 3500–4000 K. DNWs with projected average line density larger than 25 atoms Å −1 transform into double-wall CNTs. The route of transformation into CNTs clearly exhibits three stages, with the intriguing intermediate structural motif of a carbon nanoscroll (CNS). Moreover, the morphology plays an important role in the transformation involving the CNS as one important intermediate motif to form CNTs. When starting with 〈 2-bar 11〉 oriented DNWs with a square cross-section consisting of two {111} facets facing each other, one interesting structure with ‘nano-bookshelf’ shape emerges: a number of graphene ‘shelves’ located inside the CNT, bonding to the CNT walls with sp 3 hybridized atoms. The nano-bookshelf structures exist in a wide range of temperatures up to 3000 K. The further transformation from nano-bookshelf structures depends on the strength of the joints connecting shelves with CNT walls. Notably, the nano-bookshelf structure can evolve into two end products: one is CNT via the CNS pathway, the other is graphene transformed directly from the nano-bookshelf structure at high temperature. This work sheds light on the microscopic insight of carbon nanostructure formation mechanisms with the featured motifs highlighted in the pathways. (paper)

  19. Ab initio density functional calculations of ferromagnetism in low-dimensional nanostructures: From nanowires to nanorods

    Zelený, Martin; Šob, Mojmír; Hafner, J.

    2009-01-01

    Roč. 79, č. 13 (2009), 134421/1-134421/10 ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100920; GA MŠk OC 147 Institutional research plan: CEZ:AV0Z20410507 Keywords : magnetism of nanostructures * nanowires * iron * nickel Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  20. Self assembly of organic nanostructures and dielectrophoretic assembly of inorganic nanowires.

    Dholakia, Geetha; Kuo, Steven; Allen, E. L.

    2007-03-01

    Self assembly techniques enable the organization of organic molecules into nanostructures. Currently engineering strategies for efficient assembly and routine integration of inorganic nanoscale objects into functional devices is very limited. AC Dielectrophoresis is an efficient technique to manipulate inorganic nanomaterials into higher dimensional structures. We used an alumina template based sol-gel synthesis method for the growth of various metal oxide nanowires with typical diameters of 100-150 nm, ranging in length from 3-10 μm. Here we report the dielectrophoretic assembly of TiO2 nanowires, an important material for photocatalysis and photovoltaics, onto interdigitated devices. Self assembly in organic nanostructures and its dependence on structure and stereochemistry of the molecule and dielectrophoretic field dependence in the assembly of inorganic nanowires will be compared and contrasted. Tunneling spectroscopy and DOS of these nanoscale systems will also be discussed.

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

    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.

  2. Preparation and properties of novel magnetic composite nanostructures: Arrays of nanowires in porous membranes

    Vazquez, M.; Hernandez-Velez, M.; Asenjo, A.; Navas, D.; Pirota, K.; Prida, V.; Sanchez, O.; Baldonedo, J.L.

    2006-01-01

    In the present work, we introduce our latest achievements in the development of novel highly ordered composite magnetic nanostructures employing anodized nanoporous membranes as precursor templates where long-range hexagonal symmetry is induced by self-assembling during anodization process. Subsequent processing as electroplating, sputtering or pressing are employed to prepare arrays of metallic, semiconductor or polymeric nanowires embedded in oxide or metallic membranes. Particular attention is paid to recent results on controlling the magnetic anisotropy in arrays of metallic nanowires, particularly Co, and nanohole arrays in Ni membranes

  3. Size-Induced Switching of Nanowire Growth Direction: a New Approach Toward Kinked Nanostructures

    Shen, Youde

    2016-04-26

    Exploring self-assembled nanostructures with controllable architectures has been a central theme in nanoscience and nanotechnology because of the tantalizing perspective of directly integrating such bottom-up nanostructures into functional devices. Here, the growth of kinked single-crystal In2O3 nanostructures consisting of a nanocone base and a nanowire tip with an epitaxial and defect-free transition is demonstrated for the first time. By tailoring the growth conditions, a reliable switching of the growth direction from [111] to [110] or [112] is observed when the Au catalyst nanoparticles at the apexes of the nanocones shrink below ≈100 nm. The natural formation of kinked nanoarchitectures at constant growth pressures is related to the size-dependent free energy that changes for different orientations of the nanowires. The results suggest that the mechanism of forming such kinked nanocone-nanowire nanostructures in well-controlled growth environment may be universal for a wide range of functional materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Size-Induced Switching of Nanowire Growth Direction: a New Approach Toward Kinked Nanostructures

    Shen, Youde; Lebedev, Oleg I.; Turner, Stuart; Van Tendeloo, Gustaaf; Song, Xiaohui; Yu, Xuechao; Wang, Qijie; Chen, Hongyu; Dayeh, Shadi A.; Wu, Tao

    2016-01-01

    Exploring self-assembled nanostructures with controllable architectures has been a central theme in nanoscience and nanotechnology because of the tantalizing perspective of directly integrating such bottom-up nanostructures into functional devices. Here, the growth of kinked single-crystal In2O3 nanostructures consisting of a nanocone base and a nanowire tip with an epitaxial and defect-free transition is demonstrated for the first time. By tailoring the growth conditions, a reliable switching of the growth direction from [111] to [110] or [112] is observed when the Au catalyst nanoparticles at the apexes of the nanocones shrink below ≈100 nm. The natural formation of kinked nanoarchitectures at constant growth pressures is related to the size-dependent free energy that changes for different orientations of the nanowires. The results suggest that the mechanism of forming such kinked nanocone-nanowire nanostructures in well-controlled growth environment may be universal for a wide range of functional materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Fabrication of flexible silver nanowire conductive films and transmittance improvement based on moth-eye nanostructure array

    Zhang, Chengpeng; Zhu, Yuwen; Yi, Peiyun; Peng, Linfa; Lai, Xinmin

    2017-07-01

    Transparent conductive electrodes (TCEs) are widely used in optoelectronic devices, such as touch screens, liquid-crystal displays and light-emitting diodes. To date, the material of the most commonly used TCEs was indium-tin oxide (ITO), which had several intrinsic drawbacks that limited its applications in the long term, including relatively high material cost and brittleness. Silver nanowire (AgNW), as one of the alternative materials for ITO TCEs, has already gained much attention all over the world. In this paper, we reported a facile method to greatly enhance the transmittance of the AgNW TCEs without reducing the electrical conductivity based on moth-eye nanostructures, and the moth-eye nanostructures were fabricated by using a roll-to-roll ultraviolet nanoimprint lithography process. Besides, the effects of mechanical pressure and bending on the moth-eye nanostructure layer were also investigated. In the research, the optical transmittance of the flexible AgNW TCEs was enhanced from 81.3% to 86.0% by attaching moth-eye nanostructures onto the other side of the flexible polyethylene terephthalate substrate while the electrical conductivity of the AgNW TCEs was not sacrificed. This research can provide a direction for the cost-effective fabrication of moth-eye nanostructures and the transmittance improvement of the flexible transparent electrodes.

  6. Fabrication of flexible silver nanowire conductive films and transmittance improvement based on moth-eye nanostructure array

    Zhang, Chengpeng; Zhu, Yuwen; Yi, Peiyun; Peng, Linfa; Lai, Xinmin

    2017-01-01

    Transparent conductive electrodes (TCEs) are widely used in optoelectronic devices, such as touch screens, liquid-crystal displays and light-emitting diodes. To date, the material of the most commonly used TCEs was indium-tin oxide (ITO), which had several intrinsic drawbacks that limited its applications in the long term, including relatively high material cost and brittleness. Silver nanowire (AgNW), as one of the alternative materials for ITO TCEs, has already gained much attention all over the world. In this paper, we reported a facile method to greatly enhance the transmittance of the AgNW TCEs without reducing the electrical conductivity based on moth-eye nanostructures, and the moth-eye nanostructures were fabricated by using a roll-to-roll ultraviolet nanoimprint lithography process. Besides, the effects of mechanical pressure and bending on the moth-eye nanostructure layer were also investigated. In the research, the optical transmittance of the flexible AgNW TCEs was enhanced from 81.3% to 86.0% by attaching moth-eye nanostructures onto the other side of the flexible polyethylene terephthalate substrate while the electrical conductivity of the AgNW TCEs was not sacrificed. This research can provide a direction for the cost-effective fabrication of moth-eye nanostructures and the transmittance improvement of the flexible transparent electrodes. (paper)

  7. Nanostructured Zn and ZnO nanowire thin films for mechanical and self-cleaning applications

    Shaik, Ummar Pasha [Advanced Centre of Research in High Energy Materials, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); Purkayastha, Debarun Dhar, E-mail: ddebarun@yahoo.com [Department of Physics, National Institute of Technology Nagaland, Chumukedima, Dimapur 797103 (India); Krishna, M. Ghanashyam [Advanced Centre of Research in High Energy Materials, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); School of Physics, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); Madhurima, V. [Department of Physics, Central University of Tamil Nadu, Thiruvarur 610004 (India)

    2015-03-01

    Highlights: • Zn metal films were deposited by thermal evaporation, on various substrates. • Upon annealing Zn there is transformation of the Zn nanosheets into ZnO nanowires. • ZnO nanowires are superhydrophobic and exhibit wetting transition on UV exposure. • ZnO will be useful in self-cleaning, mechanical and oxidation resistance surfaces. - Abstract: Nanostructured Zn metal films were deposited by thermal evaporation, on borosilicate glass, Quartz, sapphire, lanthanum aluminate and yttria stabilized zirconia substrates. The as-deposited films are nanocrystalline and show a morphology that consists of triangular nanosheets. The films are hydrophobic with contact angles between 102° and 120° with hardness and Young's modulus between 0.15–0.8 GPa and 18–300 GPa, respectively. Thermal annealing of the films at 500 °C results only in partial oxidation of Zn to ZnO, which indicates good oxidation resistance. Annealing also causes transformation of the Zn nanosheets into ZnO nanowires that are polycrystalline in nature. The ZnO nanowires are superhydrophobic with contact angles between 159° and 162°, contact angle hysteresis between 5° and 10° and exhibit a reversible superhydrophobic–hydrophilic transition under UV irradiation. The nanowires are much softer than the as-deposited Zn metal films, with hardness between 0.02 and 0.4 GPa and Young's modulus between 3 and 35 GPa. The current study thus demonstrates a simple process for fabrication of nanostructured Zn metal films followed by a one-step transformation to nanowires with properties that will be very attractive for mechanical and self-cleaning applications.

  8. Hierarchical α-MnO2 nanowires@Ni1-x Mnx Oy nanoflakes core-shell nanostructures for supercapacitors.

    Wang, Hsin-Yi; Xiao, Fang-Xing; Yu, Le; Liu, Bin; Lou, Xiong Wen David

    2014-08-13

    A facile two-step solution-phase method has been developed for the preparation of hierarchical α-MnO2 nanowires@Ni1-x Mnx Oy nanoflakes core-shell nanostructures. Ultralong α-MnO2 nanowires were synthesized by a hydrothermal method in the first step. Subsequently, Ni1-x Mnx Oy nanoflakes were grown on α-MnO2 nanowires to form core-shell nanostructures using chemical bath deposition followed by thermal annealing. Both solution-phase methods can be easily scaled up for mass production. We have evaluated their application in supercapacitors. The ultralong one-dimensional (1D) α-MnO2 nanowires in hierarchical core-shell nanostructures offer a stable and efficient backbone for charge transport; while the two-dimensional (2D) Ni1-x Mnx Oy nanoflakes on α-MnO2 nanowires provide high accessible surface to ions in the electrolyte. These beneficial features enable the electrode with high capacitance and reliable stability. The capacitance of the core-shell α-MnO2 @Ni1-x Mnx Oy nanostructures (x = 0.75) is as high as 657 F g(-1) at a current density of 250 mA g(-1) , and stable charging-discharging cycling over 1000 times at a current density of 2000 mA g(-1) has been realized. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Crystal phase-based epitaxial growth of hybrid noble metal nanostructures on 4H/fcc Au nanowires

    Lu, Qipeng; Wang, An-Liang; Gong, Yue; Hao, Wei; Cheng, Hongfei; Chen, Junze; Li, Bing; Yang, Nailiang; Niu, Wenxin; Wang, Jie; Yu, Yifu; Zhang, Xiao; Chen, Ye; Fan, Zhanxi; Wu, Xue-Jun; Chen, Jinping; Luo, Jun; Li, Shuzhou; Gu, Lin; Zhang, Hua

    2018-03-01

    Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au-Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.

  10. Modeling of Temperature-Dependent Noise in Silicon Nanowire FETs including Self-Heating Effects

    P. Anandan

    2014-01-01

    Full Text Available Silicon nanowires are leading the CMOS era towards the downsizing limit and its nature will be effectively suppress the short channel effects. Accurate modeling of thermal noise in nanowires is crucial for RF applications of nano-CMOS emerging technologies. In this work, a perfect temperature-dependent model for silicon nanowires including the self-heating effects has been derived and its effects on device parameters have been observed. The power spectral density as a function of thermal resistance shows significant improvement as the channel length decreases. The effects of thermal noise including self-heating of the device are explored. Moreover, significant reduction in noise with respect to channel thermal resistance, gate length, and biasing is analyzed.

  11. Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires

    McDowell, Matthew T.; Cui, Yi

    2011-01-01

    Nanostructured Si is a promising anode material for the next generation of Li-ion batteries, but few studies have focused on the electrical properties of the Li-Si alloy phase, which are important for determining power capabilities and ensuring sufficient electrical conduction in the electrode structure. Here, we demonstrate an electrochemical device framework suitable for testing the electrical properties of single Si nanowires (NWs) at different lithiation states and correlating these properties with structural changes via transmission electron microscopy (TEM). We fi nd that single Si NWs usually exhibit Ohmic I - V response in the lithiated state, with conductivities two to three orders of magnitude higher than in the delithiated state. After a number of sequential lithiation/delithiation cycles, the single NWs show similar conductivity after each lithiation step but show large variations in conductivity in the delithiated state. Finally, devices with groups of NWs in physical contact were fabricated, and structural changes in the NWs were observed after lithiation to investigate how the electrical resistance of NW junctions and the NWs themselves affect the lithiation behavior. The results suggest that electrical resistance of NW junctions can limit lithiation. Overall, this study shows the importance of investigating the electronic properties of individual components of a battery electrode (single nanostructures in this case) along with studying the nature of interactions within a collection of these component structures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires

    McDowell, Matthew T.

    2011-07-19

    Nanostructured Si is a promising anode material for the next generation of Li-ion batteries, but few studies have focused on the electrical properties of the Li-Si alloy phase, which are important for determining power capabilities and ensuring sufficient electrical conduction in the electrode structure. Here, we demonstrate an electrochemical device framework suitable for testing the electrical properties of single Si nanowires (NWs) at different lithiation states and correlating these properties with structural changes via transmission electron microscopy (TEM). We fi nd that single Si NWs usually exhibit Ohmic I - V response in the lithiated state, with conductivities two to three orders of magnitude higher than in the delithiated state. After a number of sequential lithiation/delithiation cycles, the single NWs show similar conductivity after each lithiation step but show large variations in conductivity in the delithiated state. Finally, devices with groups of NWs in physical contact were fabricated, and structural changes in the NWs were observed after lithiation to investigate how the electrical resistance of NW junctions and the NWs themselves affect the lithiation behavior. The results suggest that electrical resistance of NW junctions can limit lithiation. Overall, this study shows the importance of investigating the electronic properties of individual components of a battery electrode (single nanostructures in this case) along with studying the nature of interactions within a collection of these component structures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    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. Microcantilever equipped with nanowire template electrodes for multiprobe measurement on fragile nanostructures

    Lin, Rong; Bøggild, Peter; Hansen, Ole

    2004-01-01

    cantilevers. By subsequently covering these nanowires with a metallic coating, they are made conducting and at the same time fixed to the cantilevers. These silicon nanowire four-point probes were tested on 7 and 35 nm thick Au films as well as poorly adhering 16 nm thin Au nanowires deposited on a silicon...

  15. Bias polarity-sensitive electrical failure characteristics of ZnSe nanowire in metal–semiconductor–metal nanostructure

    Yu Tan

    2014-04-01

    Full Text Available The effect of bias polarity on the electrical breakdown behavior of the single ZnSe nanowire (NW in the metal–semiconductor–metal (M–S–M nanostructure under high current density and high bias conditions has been studied in the present paper. The experimental results show that the failure of the ZnSe NW in M–S–M nanostructure was sensitive to bias polarity since the NW commonly collapsed at the negatively biased Au metal electrode due to high Joule heat produced in NW at the reversely biased Schottky barrier. Thus, the electrical breakdown behavior of the ZnSe NW was highly dominated by the cathode-controlled mode due to the high resistance of the depletion region of ZnSe NW at the reversely biased Schottky contact.

  16. Vertical nanowire architectures

    Vlad, A.; Mátéfl-Tempfli, M.; Piraux, L.

    2010-01-01

    Nanowires and statistics: A statistical process for reading ultradense arrays of nanostructured materials is presented (see image). The experimental realization is achieved through selective nanowire growth using porous alumina templates. The statistical patterning approach is found to provide ri...

  17. Porous Silicon Nanowires

    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

  18. Structural and optical properties of ZnMgO nanostructures formed by Mg in-diffused ZnO nanowires

    Pan, C.-J.; Hsu, H.-C.; Cheng, H.-M.; Wu, C.-Y.; Hsieh, W.-F.

    2007-01-01

    ZnMgO nanostructures with wurtzite phase were prepared by thermal diffusion of Mg into the ZnO nanowires. As ZnO light-emitting devices have been operated by using ZnMgO layers as energy barrier layers to confine the carriers, it is essential to realize the characterization of ZnMgO particularly. In this work, the Mg content in Zn 1 -x Mg x O alloy determined by X-ray diffraction (XRD) and photoluminescence (PL) shows a good coincidence. The variation of lattice constant and the blueshift of near-band-edge emission indicate that Zn 2+ ions are successfully substituted by Mg 2+ ions in the ZnO lattice. In Raman-scattering studies, the change of E 2 (high) phonon line shape in ZnO:Mg nanostructures reveals the microscopic substitutional disorder. In addition to the host phonons of ZnO, two additional bands around 383 and 510 cm -1 are presumably attributed to the Mg-related vibrational modes. - Graphical abstract: We reported the synthesis of the ZnMgO nanostructures prepared by a simple vapor transport method. Magnesium-related anomalous modes are observed by Raman spectra for the first time in ZnMgO system

  19. Novel detached system to MnCO3 nanowires: A self-sacrificing template for homomorphous Mn3O4 and α-Mn2O3 nanostructures

    Lei Shuijin; Peng Xiaomin; Li Xiuping; Liang Zhihong; Yang Yi; Cheng Baochang; Xiao Yanhe; Zhou Lang

    2011-01-01

    Research highlights: → A novel detached system along with solvothermal treatment was developed. → Radially aggregated MnCO 3 nanowires were successfully fabricated. → The detached system, solvent, surfactant and reaction time were important. → MnCO 3 nanowires could act as the self-sacrificing template for Mn 3 O 4 and α-Mn 2 O 3 . - Abstract: MnCO 3 , an important raw material, exhibits attractive properties and significant industrial applications. However, few concerns have been raised on the fabrication of its 1D nanostructures. In this paper, a novel detached system was successfully employed for the preparation of MnCO 3 nanowires by a surfactant-assisted solvothermal treatment using N,N-dimethylformamide as the solvent and cetyltrimethylammonium bromide as the surfactant. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were employed to study the crystal structure and morphologies of the products. Experiments showed that the detached system, solvent, surfactant and reaction time were critical for the formation of the MnCO 3 nanowires. The thermal characterization was studied by differential scanning calorimetric analysis and thermogravimetric analysis measurements. The experimental results demonstrated that the as-prepared MnCO 3 nanocrystals can act as an efficient precursor for production of homomorphous Mn 3 O 4 and α-Mn 2 O 3 nanostructures by calcination at 400 deg. C under the atmosphere of argon and air, respectively. A possible growth mechanism for the MnCO 3 nanowires was also proposed.

  20. Ag nanoparticle–ZnO nanowire hybrid nanostructures as enhanced and robust antimicrobial textiles via a green chemical approach

    Li, Zhou; Yuan, Weiwei; Song, Wei; Niu, Yongshan; Yan, Ling; Yu, Min; Dai, Ming; Feng, Siyu; Wang, Menghang; Fan, Yubo; Tang, Haoying; Liu, Tengjiao; Jiang, Peng; Wang, Zhong Lin

    2014-01-01

    A new approach for fabrication of a long-term and recoverable antimicrobial nanostructure/textile hybrid without increasing the antimicrobial resistance is demonstrated. Using in situ synthesized Ag nanoparticles (NPs) anchored on ZnO nanowires (NWs) grown on textiles by a ‘dip-in and light-irradiation’ green chemical method, we obtained ZnONW@AgNP nanocomposites with small-size and uniform Ag NPs, which have shown superior performance for antibacterial applications. These new Ag/ZnO/textile antimicrobial composites can be used for wound dressings and medical textiles for topical and prophylactic antibacterial treatments, point-of-use water treatment to improve the cleanliness of water and antimicrobial air filters to prevent bioaerosols accumulating in ventilation, heating, and air-conditioning systems. (paper)

  1. Synthesis of vertically aligned metal oxide nanostructures

    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.

  2. Controllable growth and optical properties of InP and InP/InAs nanostructures on the sidewalls of GaAs nanowires

    Yan, Xin; Zhang, Xia; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin

    2014-01-01

    The growth and optical properties of InP and InP/InAs nanostructures on GaAs nanowires are investigated. InP quantum well and quantum dots (QDs) are formed on the sidewalls of GaAs nanowires successively with increasing the deposition time of InP. The GaAs/InP nanowire heterostructure exhibits a type-II band alignment. The wavelength of the InP quantum well is in the range of 857–892 nm at 77 K, which means that the quantum well is nearly fully strained. The InP quantum dot, which has a bow-shaped cross section, exhibits dislocation-free pure zinc blende structure. Stranski-Krastanow InAs quantum dots are subsequently formed on the GaAs/InP nanowire core-shell structure. The InAs quantum dots are distributed over the middle part of the nanowire, indicating that the In atoms contributing to the quantum dots mainly come from the vapor rather than the substrate. The longest emission wavelength obtained from the InAs QDs is 1039 nm at 77 K. The linewidth is as narrow as 46.3 meV, which is much narrower than those on planar InP substrates and wurtzite InP nanowires, suggesting high-crystal-quality, phase-purity, and size-uniformity of quantum dots

  3. Fabrication of conductive metallized nanostructures from self-assembled amphiphilic triblock copolymer templates: Nanospheres, nanowires, nanorings

    Zhu Jintao; Jiang Wei

    2007-01-01

    Various metallized nanostructures (such as rings, wires with controllable lengths, spheres) have been successfully fabricated by coating metallic nanolayers onto soft nanotemplates through simple electroless methods. In particular, bimetallic nanostructures have been obtained by using simple methods. The multiple functional polymeric nanostructures were obtained through the self-assembly of polystyrene/poly(4-vinyl pyridine) triblock copolymer (P4VP-b-PS-b-P4VP) in selective media by changing the common solvent properties. By combining field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization, it was confirmed that polymer/metal and bimetallic (Au at Ag) core-shell nanostructures could be achieved by chemical metal deposition method

  4. Au nanostructure-decorated TiO2 nanowires exhibiting photoactivity across entire UV-visible region for photoelectrochemical water splitting.

    Pu, Ying-Chih; Wang, Gongming; Chang, Kao-Der; Ling, Yichuan; Lin, Yin-Kai; Fitzmorris, Bob C; Liu, Chia-Ming; Lu, Xihong; Tong, Yexiang; Zhang, Jin Z; Hsu, Yung-Jung; Li, Yat

    2013-08-14

    Here we demonstrate that the photoactivity of Au-decorated TiO2 electrodes for photoelectrochemical water oxidation can be effectively enhanced in the entire UV-visible region from 300 to 800 nm by manipulating the shape of the decorated Au nanostructures. The samples were prepared by carefully depositing Au nanoparticles (NPs), Au nanorods (NRs), and a mixture of Au NPs and NRs on the surface of TiO2 nanowire arrays. As compared with bare TiO2, Au NP-decorated TiO2 nanowire electrodes exhibited significantly enhanced photoactivity in both the UV and visible regions. For Au NR-decorated TiO2 electrodes, the photoactivity enhancement was, however, observed in the visible region only, with the largest photocurrent generation achieved at 710 nm. Significantly, TiO2 nanowires deposited with a mixture of Au NPs and NRs showed enhanced photoactivity in the entire UV-visible region. Monochromatic incident photon-to-electron conversion efficiency measurements indicated that excitation of surface plasmon resonance of Au is responsible for the enhanced photoactivity of Au nanostructure-decorated TiO2 nanowires. Photovoltage experiment showed that the enhanced photoactivity of Au NP-decorated TiO2 in the UV region was attributable to the effective surface passivation of Au NPs. Furthermore, 3D finite-difference time domain simulation was performed to investigate the electrical field amplification at the interface between Au nanostructures and TiO2 upon SPR excitation. The results suggested that the enhanced photoactivity of Au NP-decorated TiO2 in the UV region was partially due to the increased optical absorption of TiO2 associated with SPR electrical field amplification. The current study could provide a new paradigm for designing plasmonic metal/semiconductor composite systems to effectively harvest the entire UV-visible light for solar fuel production.

  5. Reactor and method for production of nanostructures

    Sunkara, Mahendra Kumar; Kim, Jeong H.; Kumar, Vivekanand

    2017-04-25

    A reactor and method for production of nanostructures, including metal oxide nanowires or nanoparticles, are provided. The reactor includes a regulated metal powder delivery system in communication with a dielectric tube; a plasma-forming gas inlet, whereby a plasma-forming gas is delivered substantially longitudinally into the dielectric tube; a sheath gas inlet, whereby a sheath gas is delivered into the dielectric tube; and a microwave energy generator coupled to the dielectric tube, whereby microwave energy is delivered into a plasma-forming gas. The method for producing nanostructures includes providing a reactor to form nanostructures and collecting the formed nanostructures, optionally from a filter located downstream of the dielectric tube.

  6. Predictive simulations and optimization of nanowire field-effect PSA sensors including screening

    Baumgartner, Stefan; Heitzinger, Clemens; Vacic, Aleksandar; Reed, Mark A

    2013-01-01

    We apply our self-consistent PDE model for the electrical response of field-effect sensors to the 3D simulation of nanowire PSA (prostate-specific antigen) sensors. The charge concentration in the biofunctionalized boundary layer at the semiconductor-electrolyte interface is calculated using the propka algorithm, and the screening of the biomolecules by the free ions in the liquid is modeled by a sensitivity factor. This comprehensive approach yields excellent agreement with experimental current-voltage characteristics without any fitting parameters. Having verified the numerical model in this manner, we study the sensitivity of nanowire PSA sensors by changing device parameters, making it possible to optimize the devices and revealing the attributes of the optimal field-effect sensor. © 2013 IOP Publishing Ltd.

  7. Predictive simulations and optimization of nanowire field-effect PSA sensors including screening

    Baumgartner, Stefan

    2013-05-03

    We apply our self-consistent PDE model for the electrical response of field-effect sensors to the 3D simulation of nanowire PSA (prostate-specific antigen) sensors. The charge concentration in the biofunctionalized boundary layer at the semiconductor-electrolyte interface is calculated using the propka algorithm, and the screening of the biomolecules by the free ions in the liquid is modeled by a sensitivity factor. This comprehensive approach yields excellent agreement with experimental current-voltage characteristics without any fitting parameters. Having verified the numerical model in this manner, we study the sensitivity of nanowire PSA sensors by changing device parameters, making it possible to optimize the devices and revealing the attributes of the optimal field-effect sensor. © 2013 IOP Publishing Ltd.

  8. Electron transport properties in ZnO nanowires/poly(3-hexylthiophene) hybrid nanostructure

    Cheng Ke; Cheng Gang; Wang Shujie; Fu Dongwei; Zou Bingsuo; Du Zuliang

    2010-01-01

    The ZnO nanowires (NWs) array/poly(3-hexylthiophene) (P3HT) hybrid prototype device was fabricated. An ultraviolet (UV) light of λ = 350 nm is used to investigate the photo-electric properties of the ZnO NWs array and hybrid structure. In this way, we can avoid the excitation of P3HT, which can give us a real electron transport ability of ZnO NWs itself. Our results demonstrated a higher and faster photo-electric response of 3 s for the hybrid structure while 9 s for the ZnO NWs array. The surface states related slow photo-electric response was also observed for them. The charge transfer mechanism and the influence of surface states were discussed. The current work provides us profound understandings on the electron transport ability of ZnO NWs array in a working hybrid polymer solar cell, which is crucial for optimizing the device performance.

  9. Controlled Self-Assembly of Low-Dimensional Alq3 Nanostructures from 1D Nanowires to 2D Plates via Intermolecular Interactions

    Gu, Jianmin; Yin, Baipeng; Fu, Shaoyan; Jin, Cuihong; Liu, Xin; Bian, Zhenpan; Li, Jianjun; Wang, Lu; Li, Xiaoyu

    2018-03-01

    Due to the intense influence of the shape and size of the photon building blocks on the limitation and guidance of optical waves, an important strategy is the fabrication of different structures. Herein, organic semiconductor tris-(8-hydroxyquinoline)aluminium (Alq3) nanostructures with controllable morphology, ranging from one-dimensional nanowires to two-dimensional plates, have been prepared through altering intermolecular interactions with employing the anti-solvent diffusion cooperate with solvent-volatilization induced self-assembly method. The morphologies of the formed nanostructures, which are closely related to the stacking modes of the molecules, can be exactly controlled by altering the polarity of anti-solvents that can influence various intermolecular interactions. The synthesis strategy reported here can potentially be extended to other functional organic nanomaterials.

  10. Bulk to nanostructured vanadium pentaoxide-nanowires (V2O5-NWs) for high energy density supercapacitors

    Ahirrao, Dinesh J.; Mohanapriya., K.; Jha, Neetu

    2018-04-01

    Vanadium pentoxide (V2O5) has attracted huge attention in field of energy storage including supercapacitor electrodes due to its low cost and layered structure. In this present study, Bulk V2O5 has been prepared by the calcination of ammonium metavanadate followed by the synthesis of V2O5-nanowires (V2O5-NWs) by hydrothermal treatment of bulk V2O5. Obtained V2O5-NWs was further used to fabricate the supercapacitor electrodes. Structure and morphology analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). Energy storage capability of as prepared nanowires was investigated by Galvanostatic charge-discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in aqueous electrolyte (1M H2SO4). High specific capacitantance of about 622 F/g was achieved at 1 A/g. Along with high storage by faradic charge storage mechanism; V2O5-NWs electrodes also possess high stability. It could retain 63% of its initial capacitance even after 1000 GCD cycles. Excellent performance of V2O5-NWs promotes its commercial utilization for the development of high performance supercapacitors.

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

    Chen Yong; Luo Guanghong; Diao Jiajie; Chornoguz, Olesya; Reeves, Mark; Vertes, Akos

    2007-01-01

    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 3xω Nd:YAG laser in air, SF 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 ∼2 μm in SF 6 gas and to ∼5 μm 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 (∼10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits

  12. Metal nanogrids, nanowires, and nanofibers for transparent electrodes

    Hu, Liangbing; Wu, Hui; Cui, Yi

    2011-01-01

    Metals possess the highest conductivity among all room-temperature materials; however, ultrathin metal films demonstrate decent optical transparency but poor sheet conductance due to electron scattering from the surface and grain boundaries. This article discusses engineered metal nanostructures in the form of nanogrids, nanowires, or continuous nanofibers as efficient transparent and conductive electrodes. Metal nanogrids are discussed, as they represent an excellent platform for understanding the fundamental science. Progress toward low-cost, nano-ink-based printed silver nanowire electrodes, including silver nanowire synthesis, film fabrication, wire-wire junction resistance, optoelectronic properties, and stability, are also discussed. Another important factor for low-cost application is to use earth-abundant materials. Copper-based nanowires and nanofibers are discussed in this context. Examples of device integrations of these materials are also given. Such metal nanostructure-based transparent electrodes are particularly attractive for solar cell applications. © 2011 Materials Research Society.

  13. Metal nanogrids, nanowires, and nanofibers for transparent electrodes

    Hu, Liangbing

    2011-10-01

    Metals possess the highest conductivity among all room-temperature materials; however, ultrathin metal films demonstrate decent optical transparency but poor sheet conductance due to electron scattering from the surface and grain boundaries. This article discusses engineered metal nanostructures in the form of nanogrids, nanowires, or continuous nanofibers as efficient transparent and conductive electrodes. Metal nanogrids are discussed, as they represent an excellent platform for understanding the fundamental science. Progress toward low-cost, nano-ink-based printed silver nanowire electrodes, including silver nanowire synthesis, film fabrication, wire-wire junction resistance, optoelectronic properties, and stability, are also discussed. Another important factor for low-cost application is to use earth-abundant materials. Copper-based nanowires and nanofibers are discussed in this context. Examples of device integrations of these materials are also given. Such metal nanostructure-based transparent electrodes are particularly attractive for solar cell applications. © 2011 Materials Research Society.

  14. Structural and optical properties of silicon-carbide nanowires produced by the high-temperature carbonization of silicon nanostructures

    Pavlikov, A. V., E-mail: pavlikov@physics.msu.ru [Moscow State University, Faculty of Physics (Russian Federation); Latukhina, N. V.; Chepurnov, V. I. [Samara National Researh University (Russian Federation); Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation)

    2017-03-15

    Silicon-carbide (SiC) nanowire structures 40–50 nm in diameter are produced by the high-temperature carbonization of porous silicon and silicon nanowires. The SiC nanowires are studied by scanning electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and infrared reflectance spectroscopy. The X-ray structural and Raman data suggest that the cubic 3C-SiC polytype is dominant in the samples under study. The shape of the infrared reflectance spectrum in the region of the reststrahlen band 800–900 cm{sup –1} is indicative of the presence of free charge carriers. The possibility of using SiC nanowires in microelectronic, photonic, and gas-sensing devices is discussed.

  15. Hydrogenated CoOx nanowire@Ni(OH)2 nanosheet core-shell nanostructures for high-performance asymmetric supercapacitors

    Zhu, Jianxiao; Huang, Lei; Xiao, Yuxiu; Shen, Leo; Chen, Qi; Shi, Wangzhou

    2014-05-01

    We report a facile strategy to prepare 3D core-shell nanowire heterostructures with microporous hydrogenated CoOx (H-CoOx) nanowires as the conducting scaffold to support Ni(OH)2 nanosheets. Benefiting from the H-CoOx nanowire core to provide the effective pathway for charge transport and the core-shell heterostructures with synergistic effects, the H-CoOx@Ni(OH)2 core-shell nanowire electrode achieved the specific capacitance of 2196 F g-1 (areal capacitance of 5.73 F cm-2), which is approximately a 1.4-fold enhancement compared with the Co3O4@Ni(OH)2 core-shell nanowires. An aqueous asymmetric supercapacitor (ASC) device was fabricated by using H-CoOx@Ni(OH)2 nanowires as the positive electrode and reduced graphene oxide @Fe3O4 nanocomposites as the negative electrode. The ASCs achieved high energy density (~45.3 W h kg-1 at 1010 W kg-1), high power density (~7080 W kg-1 at 23.4 W h kg-1) and high cycling stability. Furthermore, after charging for ~1 min, one such 22 cm2 ASC device demonstrated to be able to drive a small windmill (0.8 V, 0.1 W) for 20 min. Two such ASCs connected in series can power up a seven-color LED (3.2 V) efficiently.We report a facile strategy to prepare 3D core-shell nanowire heterostructures with microporous hydrogenated CoOx (H-CoOx) nanowires as the conducting scaffold to support Ni(OH)2 nanosheets. Benefiting from the H-CoOx nanowire core to provide the effective pathway for charge transport and the core-shell heterostructures with synergistic effects, the H-CoOx@Ni(OH)2 core-shell nanowire electrode achieved the specific capacitance of 2196 F g-1 (areal capacitance of 5.73 F cm-2), which is approximately a 1.4-fold enhancement compared with the Co3O4@Ni(OH)2 core-shell nanowires. An aqueous asymmetric supercapacitor (ASC) device was fabricated by using H-CoOx@Ni(OH)2 nanowires as the positive electrode and reduced graphene oxide @Fe3O4 nanocomposites as the negative electrode. The ASCs achieved high energy density (~45.3 W h kg-1 at

  16. Ultra violet sensors based on nanostructured ZnO spheres in network of nanowires: a novel approach

    Hullavarad, SS; Hullavarad, NV; Karulkar, PC; Luykx, A; Valdivia, P

    2007-01-01

    AbstractThe ZnO nanostructures consisting of micro spheres in a network of nano wires were synthesized by direct vapor phase method. X-ray Photoelectron Spectroscopy measurements were carried out to understand the chemical nature of the sample. ZnO nanostructures exhibited band edge luminescence at 383 nm. The nanostructure based ZnO thin films were used to fabricate UV sensors. The photoresponse measurements were carried out and the responsivity was measured to be 50 mA W−1. The rise a...

  17. Ultra violet sensors based on nanostructured ZnO spheres in network of nanowires: a novel approach

    Luykx A

    2007-01-01

    Full Text Available AbstractThe ZnO nanostructures consisting of micro spheres in a network of nano wires were synthesized by direct vapor phase method. X-ray Photoelectron Spectroscopy measurements were carried out to understand the chemical nature of the sample. ZnO nanostructures exhibited band edge luminescence at 383 nm. The nanostructure based ZnO thin films were used to fabricate UV sensors. The photoresponse measurements were carried out and the responsivity was measured to be 50 mA W−1. The rise and decay time measurements were also measured.

  18. Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires

    He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

    2017-06-01

    In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g-1 at a scan rate of 20 mV s-1, which is almost twice that of ZnO NWs (191.5 F g-1). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g-1 at a current density of 1.33 A g-1 with an energy density of 25.2 W h kg-1 at the power density of 896.44 W kg-1. In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

  19. Inorganic nanostructured materials for high performance electrochemical supercapacitors

    Liu, Sheng; Sun, Shouheng; You, Xiao-Zeng

    2014-01-01

    Electrochemical supercapacitors (ES) are a well-known energy storage system that has high power density, long life-cycle and fast charge-discharge kinetics. Nanostructured materials are a new generation of electrode materials with large surface area and short transport/diffusion path for ions and electrons to achieve high specific capacitance in ES. This mini review highlights recent developments of inorganic nanostructure materials, including carbon nanomaterials, metal oxide nanoparticles, and metal oxide nanowires/nanotubes, for high performance ES applications.

  20. Biotemplated synthesis of PZT nanowires.

    Cung, Kellye; Han, Booyeon J; Nguyen, Thanh D; Mao, Sheng; Yeh, Yao-Wen; Xu, Shiyou; Naik, Rajesh R; Poirier, Gerald; Yao, Nan; Purohit, Prashant K; McAlpine, Michael C

    2013-01-01

    Piezoelectric nanowires are an important class of smart materials for next-generation applications including energy harvesting, robotic actuation, and bioMEMS. Lead zirconate titanate (PZT), in particular, has attracted significant attention, owing to its superior electromechanical conversion performance. Yet, the ability to synthesize crystalline PZT nanowires with well-controlled properties remains a challenge. Applications of common nanosynthesis methods to PZT are hampered by issues such as slow kinetics, lack of suitable catalysts, and harsh reaction conditions. Here we report a versatile biomimetic method, in which biotemplates are used to define PZT nanostructures, allowing for rational control over composition and crystallinity. Specifically, stoichiometric PZT nanowires were synthesized using both polysaccharide (alginate) and bacteriophage templates. The wires possessed measured piezoelectric constants of up to 132 pm/V after poling, among the highest reported for PZT nanomaterials. Further, integrated devices can generate up to 0.820 μW/cm(2) of power. These results suggest that biotemplated piezoelectric nanowires are attractive candidates for stimuli-responsive nanosensors, adaptive nanoactuators, and nanoscale energy harvesters.

  1. Production of zinc oxide nanowires power with precisely defined morphology

    Mičová, Júlia; Remeš, Zdeněk; Chan, Yu-Ying

    2017-12-01

    The interest about zinc oxide is increasing thanks to its unique chemical and physical properties. Our attention has focused on preparation powder of 1D nanostructures of ZnO nanowires with precisely defined morphology include characterization size (length and diameter) and shape controlled in the scanning electron microscopy (SEM). We have compared results of SEM with dynamic light scattering (DLS) technique. We have found out that SEM method gives more accurate results. We have proposed transformation process from ZnO nanowires on substrates to ZnO nanowires powder by ultrasound peeling to colloid followed by lyophilization. This method of the mass production of the ZnO nanowires powder has some advantages: simplicity, cost effective, large-scale and environment friendly.

  2. EDITORIAL: Nanowires for energy Nanowires for energy

    LaPierre, Ray; Sunkara, Mahendra

    2012-05-01

    This special issue of Nanotechnology focuses on studies illustrating the application of nanowires for energy including solar cells, efficient lighting and water splitting. Over the next three decades, nanotechnology will make significant contributions towards meeting the increased energy needs of the planet, now known as the TeraWatt challenge. Nanowires in particular are poised to contribute significantly in this development as presented in the review by Hiralal et al [1]. Nanowires exhibit light trapping properties that can act as a broadband anti-reflection coating to enhance the efficiency of solar cells. In this issue, Li et al [2] and Wang et al [3] present the optical properties of silicon nanowire and nanocone arrays. In addition to enhanced optical properties, core-shell nanowires also have the potential for efficient charge carrier collection across the nanowire diameter as presented in the contribution by Yu et al [4] for radial junction a-Si solar cells. Hybrid approaches that combine organic and inorganic materials also have potential for high efficiency photovoltaics. A Si-based hybrid solar cell is presented by Zhang et al [5] with a photoconversion efficiency of over 7%. The quintessential example of hybrid solar cells is the dye-sensitized solar cell (DSSC) where an organic absorber (dye) coats an inorganic material (typically a ZnO nanostructure). Herman et al [6] present a method of enhancing the efficiency of a DSSC by increasing the hetero-interfacial area with a unique hierarchical weeping willow ZnO structure. The increased surface area allows for higher dye loading, light harvesting, and reduced charge recombination through direct conduction along the ZnO branches. Another unique ZnO growth method is presented by Calestani et al [7] using a solution-free and catalyst-free approach by pulsed electron deposition (PED). Nanowires can also make more efficient use of electrical power. Light emitting diodes, for example, will eventually become the

  3. Towards an elastic model of wurtzite AlN nanowires

    Mitrushchenkov, A; Chambaud, G; Yvonnet, J; He, Q-C

    2010-01-01

    Starting with ab initio calculations of AlN wurtzite [0001] nanowires with diameters up to 4 nm, a finite element method is developed to deal with larger nanostructures/nanoparticles. The ab initio calculations show that the structure of the nanowires can be well represented by an internal part with AlN bulk elastic properties, and one atomic surface layer with its own elastic behavior. The proposed finite element method includes surface elements with their own elastic properties using surface elastic coefficients deduced from the ab initio calculations. The elastic properties obtained with the finite element model compare very well with those obtained with the full ab initio calculations.

  4. Membrane for distillation including nanostructures, methods of making membranes, and methods of desalination and separation

    Lai, Zhiping; Huang, Kuo-Wei; Chen, Wei

    2016-01-01

    In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure provide membranes, methods of making the membrane, systems including the membrane, methods of separation, methods of desalination, and the like.

  5. Membrane for distillation including nanostructures, methods of making membranes, and methods of desalination and separation

    Lai, Zhiping

    2016-01-21

    In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure provide membranes, methods of making the membrane, systems including the membrane, methods of separation, methods of desalination, and the like.

  6. Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

    Ping Feng

    2014-09-01

    Full Text Available One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concentration of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concentration of the gas molecules. In addition, extra controls such as metal decoration, local heating and light irradiation can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed.

  7. A model for the impact of the nanostructure size on its gas sensing properties

    Alenezi, Mohammad R.; Alzanki, T.H.; Almeshal, A.M.

    2015-01-01

    The size of a metal oxide nanostructure plays a key role in its performance as a gas sensor. ZnO nanostructures with different morphologies including nanowires at different diameters and nanodisks at different thicknesses were synthesized hydrothermally. Gas sensors based on individual...... of the surface to volume ratio as well as the depletion region of the nanostructure. This work can be simply generalized for other metal oxides to enhance their performance as gas sensors....... nanostructures with different sizes were fabricated and their sensing properties were compared and investigated. Nanowires with smaller diameter size and higher surface to volume ratio showed enhanced gas sensing performance. Also, as the nanodisk thickness gets closer to the thickness of the ZnO depletion layer...

  8. Alignment control and atomically-scaled heteroepitaxial interface study of GaN nanowires.

    Liu, Qingyun; Liu, Baodan; Yang, Wenjin; Yang, Bing; Zhang, Xinglai; Labbé, Christophe; Portier, Xavier; An, Vladimir; Jiang, Xin

    2017-04-20

    Well-aligned GaN nanowires are promising candidates for building high-performance optoelectronic nanodevices. In this work, we demonstrate the epitaxial growth of well-aligned GaN nanowires on a [0001]-oriented sapphire substrate in a simple catalyst-assisted chemical vapor deposition process and their alignment control. It is found that the ammonia flux plays a key role in dominating the initial nucleation of GaN nanocrystals and their orientation. Typically, significant improvement of the GaN nanowire alignment can be realized at a low NH 3 flow rate. X-ray diffraction and cross-sectional scanning electron microscopy studies further verified the preferential orientation of GaN nanowires along the [0001] direction. The growth mechanism of GaN nanowire arrays is also well studied based on cross-sectional high-resolution transmission electron microscopy (HRTEM) characterization and it is observed that GaN nanowires have good epitaxial growth on the sapphire substrate following the crystallographic relationship between (0001) GaN ∥(0001) sapphire and (101[combining macron]0) GaN ∥(112[combining macron]0) sapphire . Most importantly, periodic misfit dislocations are also experimentally observed in the interface region due to the large lattice mismatch between the GaN nanowire and the sapphire substrate, and the formation of such dislocations will favor the release of structural strain in GaN nanowires. HRTEM analysis also finds the existence of "type I" stacking faults and voids inside the GaN nanowires. Optical investigation suggests that the GaN nanowire arrays have strong emission in the UV range, suggesting their crystalline nature and chemical purity. The achievement of aligned GaN nanowires will further promote the wide applications of GaN nanostructures toward diverse high-performance optoelectronic nanodevices including nano-LEDs, photovoltaic cells, photodetectors etc.

  9. Copercolating Networks: An Approach for Realizing High-Performance Transparent Conductors using Multicomponent Nanostructured Networks

    Das Suprem R.

    2016-06-01

    Full Text Available Although transparent conductive oxides such as indium tin oxide (ITO are widely employed as transparent conducting electrodes (TCEs for applications such as touch screens and displays, new nanostructured TCEs are of interest for future applications, including emerging transparent and flexible electronics. A number of twodimensional networks of nanostructured elements have been reported, including metallic nanowire networks consisting of silver nanowires, metallic carbon nanotubes (m-CNTs, copper nanowires or gold nanowires, and metallic mesh structures. In these single-component systems, it has generally been difficult to achieve sheet resistances that are comparable to ITO at a given broadband optical transparency. A relatively new third category of TCEs consisting of networks of 1D-1D and 1D-2D nanocomposites (such as silver nanowires and CNTs, silver nanowires and polycrystalline graphene, silver nanowires and reduced graphene oxide have demonstrated TCE performance comparable to, or better than, ITO. In such hybrid networks, copercolation between the two components can lead to relatively low sheet resistances at nanowire densities corresponding to high optical transmittance. This review provides an overview of reported hybrid networks, including a comparison of the performance regimes achievable with those of ITO and single-component nanostructured networks. The performance is compared to that expected from bulk thin films and analyzed in terms of the copercolation model. In addition, performance characteristics relevant for flexible and transparent applications are discussed. The new TCEs are promising, but significant work must be done to ensure earth abundance, stability, and reliability so that they can eventually replace traditional ITO-based transparent conductors.

  10. Soft plasma processing of organic nanowires: a route for the fabrication of 1D organic heterostructures and the template synthesis of inorganic 1D nanostructures.

    Alcaire, Maria; Sanchez-Valencia, Juan R; Aparicio, Francisco J; Saghi, Zineb; Gonzalez-Gonzalez, Juan C; Barranco, Angel; Zian, Youssef Oulad; Gonzalez-Elipe, Agustin R; Midgley, Paul; Espinos, Juan P; Groening, Pierangelo; Borras, Ana

    2011-11-01

    Hierarchical (branched) and hybrid metal-NPs/organic supported NWs are fabricated through controlled plasma processing of metalloporphyrin, metallophthalocyanine and perylene nanowires. The procedure is also applied for the development of a general template route for the synthesis of supported metal and metal oxide nanowires.

  11. Nanowire structures and electrical devices

    Bezryadin, Alexey; Remeika, Mikas

    2010-07-06

    The present invention provides structures and devices comprising conductive segments and conductance constricting segments of a nanowire, such as metallic, superconducting or semiconducting nanowire. The present invention provides structures and devices comprising conductive nanowire segments and conductance constricting nanowire segments having accurately selected phases including crystalline and amorphous states, compositions, morphologies and physical dimensions, including selected cross sectional dimensions, shapes and lengths along the length of a nanowire. Further, the present invention provides methods of processing nanowires capable of patterning a nanowire to form a plurality of conductance constricting segments having selected positions along the length of a nanowire, including conductance constricting segments having reduced cross sectional dimensions and conductance constricting segments comprising one or more insulating materials such as metal oxides.

  12. Template synthesis of indium nanowires using anodic aluminum oxide membranes.

    Chen, Feng; Kitai, Adrian H

    2008-09-01

    Indium nanowires with diameters approximately 300 nm have been synthesized by a hydraulic pressure technique using anodic aluminum oxide (AAO) templates. The indium melt is injected into the AAO template and solidified to form nanostructures. The nanowires are dense, continuous and uniformly run through the entire approximately 60 microm thickness of the AAO template. X-ray diffraction (XRD) reveals that the nanowires are polycrystalline with a preferred orientation. SEM is performed to characterize the morphology of the nanowires.

  13. Tuning and synthesis of semiconductor nanostructures by mechanical compression

    Fan, Hongyou; Li, Binsong

    2015-11-17

    A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

  14. Synthesis of platinum nanowire networks using a soft template.

    Song, Yujiang; Garcia, Robert M; Dorin, Rachel M; Wang, Haorong; Qiu, Yan; Coker, Eric N; Steen, William A; Miller, James E; Shelnutt, John A

    2007-12-01

    Platinum nanowire networks have been synthesized by chemical reduction of a platinum complex using sodium borohydride in the presence of a soft template formed by cetyltrimethylammonium bromide in a two-phase water-chloroform system. The interconnected polycrystalline nanowires possess the highest surface area (53 +/- 1 m2/g) and electroactive surface area (32.4 +/- 3.6 m2/g) reported for unsupported platinum nanomaterials; the high surface area results from the small average diameter of the nanowires (2.2 nm) and the 2-10 nm pores determined by nitrogen adsorption measurements. Synthetic control over the network was achieved simply by varying the stirring rate and reagent concentrations, in some cases leading to other types of nanostructures including wormlike platinum nanoparticles. Similarly, substitution of a palladium complex for platinum gives palladium nanowire networks. A mechanism of formation of the metal nanowire networks is proposed based on confined metal growth within a soft template consisting of a network of swollen inverse wormlike micelles.

  15. Synthesis and Growth Mechanism of Ni Nanotubes and Nanowires

    Wang Yiqian

    2009-01-01

    Full Text Available Abstract Highly ordered Ni nanotube and nanowire arrays were fabricated via electrodeposition. The Ni microstructures and the process of the formation were investigated using conventional and high-resolution transmission electron microscope. Herein, we demonstrated the systematic fabrication of Ni nanotube and nanowire arrays and proposed an original growth mechanism. With the different deposition time, nanotubes or nanowires can be obtained. Tubular nanostructures can be obtained at short time, while nanowires take longer time to form. This formation mechanism is applicable to design and synthesize other metal nanostructures and even compound nanostuctures via template-based electrodeposition.

  16. Advanced Nanostructured Magnetic Materials

    Sellmyer, David J

    2004-01-01

    ... out. Novel physical systems have been synthesized and studied including: hard/soft nanocomposites, magnetic nanowires, thermally processed multilayer films, and nanoparticle-assembled composites...

  17. Investigations of inorganic and hybrid inorganic-organic nanostructures

    Kam, Kinson Chihang

    This thesis focuses on the exploratory synthesis and characterization of inorganic and hybrid inorganic-organic nanomaterials. In particular, nanostructures of semiconducting nitrides and oxides, and hybrid systems of nanowire-polymer composites and framework materials, are investigated. These materials are characterized by a variety of techniques for structure, composition, morphology, surface area, optical properties, and electrical properties. In the study of inorganic nanomaterials, gallium nitride (GaN), indium oxide (In2O3), and vanadium dioxide (VO2) nanostructures were synthesized using different strategies and their physical properties were examined. GaN nanostructures were obtained from various synthetic routes. Solid-state ammonolysis of metastable gamma-Ga2O 3 nanoparticles was found to be particularly successful; they achieved high surface areas and photoluminescent study showed a blue shift in emission as a result of surface and size defects. Similarly, In2O3 nanostructures were obtained by carbon-assisted solid-state syntheses. The sub-oxidic species, which are generated via a self-catalyzed vapor-liquid-solid mechanism, resulted in 1D nanostructures including nanowires, nanotrees, and nanobouquets upon oxidation. On the other hand, hydrothermal methods were used to obtain VO2 nanorods. After post-thermal treatment, infrared spectroscopy demonstrated that these nanorods exhibit a thermochromic transition with temperature that is higher by ˜10°C compared to the parent material. The thermochromic behavior indicated a semiconductor-to-metal transition associated with a structural transformation from monoclinic to rutile. The hybrid systems, on the other hand, enabled their properties to be tunable. In nanowire-polymer composites, zinc oxide (ZnO) and silver (Ag) nanowires were synthesized and incorporated into polyaniline (PANI) and polypyrrole (PPy) via in-situ and ex-situ polymerization method. The electrical properties of these composites are

  18. Nanostructures by ion beams

    Schmidt, B.

    Ion beam techniques, including conventional broad beam ion implantation, ion beam synthesis and ion irradiation of thin layers, as well as local ion implantation with fine-focused ion beams have been applied in different fields of micro- and nanotechnology. The ion beam synthesis of nanoparticles in high-dose ion-implanted solids is explained as phase separation of nanostructures from a super-saturated solid state through precipitation and Ostwald ripening during subsequent thermal treatment of the ion-implanted samples. A special topic will be addressed to self-organization processes of nanoparticles during ion irradiation of flat and curved solid-state interfaces. As an example of silicon nanocrystal application, the fabrication of silicon nanocrystal non-volatile memories will be described. Finally, the fabrication possibilities of nanostructures, such as nanowires and chains of nanoparticles (e.g. CoSi2), by ion beam synthesis using a focused Co+ ion beam will be demonstrated and possible applications will be mentioned.

  19. Study of GaN nanowires converted from β-Ga2O3 and photoconduction in a single nanowire

    Kumar, Mukesh; Kumar, Sudheer; Chauhan, Neha; Sakthi Kumar, D.; Kumar, Vikram; Singh, R.

    2017-08-01

    The formation of GaN nanowires from β-Ga2O3 nanowires and photoconduction in a fabricated single GaN nanowire device has been studied. Wurtzite phase GaN were formed from monoclinic β-Ga2O3 nanowires with or without catalyst particles at their tips. The formation of faceted nanostructures from catalyst droplets presented on a nanowire tip has been discussed. The nucleation of GaN phases in β-Ga2O3 nanowires and their subsequent growth due to interfacial strain energy has been examined using a high resolution transmission electron microscope. The high quality of the converted GaN nanowire is confirmed by fabricating single nanowire photoconducting devices which showed ultra high responsivity under ultra-violet illumination.

  20. Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

    Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

    2013-03-01

    Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

  1. A four-probe thermal transport measurement method for nanostructures

    Kim, Jaehyun; Ou, Eric; Sellan, Daniel P.; Shi, Li, E-mail: lishi@mail.utexas.edu [Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2015-04-15

    Several experimental techniques reported in recent years have enabled the measurement of thermal transport properties of nanostructures. However, eliminating the contact thermal resistance error from the measurement results has remained a critical challenge. Here, we report a different four-probe measurement method that can separately obtain both the intrinsic thermal conductance and the contact thermal resistance of individual nanostructures. The measurement device consists of four microfabricated, suspended metal lines that act as resistive heaters and thermometers, across which the nanostructure sample is assembled. The method takes advantage of the variation in the heat flow along the suspended nanostructure and across its contacts to the four suspended heater and thermometer lines, and uses sixteen sets of temperature and heat flow measurements to obtain nine of the thermal resistances in the measurement device and the nanostructure sample, including the intrinsic thermal resistance and the two contact thermal resistances to the middle suspended segment of the nanostructure. Two single crystalline Si nanowires with different cross sections are measured in this work to demonstrate the effectiveness of the method. This four-probe thermal transport measurement method can lead to future discoveries of unique size-dependent thermal transport phenomena in nanostructures and low-dimensional materials, in addition to providing reliable experimental data for calibrating theoretical models.

  2. A four-probe thermal transport measurement method for nanostructures

    Kim, Jaehyun; Ou, Eric; Sellan, Daniel P.; Shi, Li

    2015-01-01

    Several experimental techniques reported in recent years have enabled the measurement of thermal transport properties of nanostructures. However, eliminating the contact thermal resistance error from the measurement results has remained a critical challenge. Here, we report a different four-probe measurement method that can separately obtain both the intrinsic thermal conductance and the contact thermal resistance of individual nanostructures. The measurement device consists of four microfabricated, suspended metal lines that act as resistive heaters and thermometers, across which the nanostructure sample is assembled. The method takes advantage of the variation in the heat flow along the suspended nanostructure and across its contacts to the four suspended heater and thermometer lines, and uses sixteen sets of temperature and heat flow measurements to obtain nine of the thermal resistances in the measurement device and the nanostructure sample, including the intrinsic thermal resistance and the two contact thermal resistances to the middle suspended segment of the nanostructure. Two single crystalline Si nanowires with different cross sections are measured in this work to demonstrate the effectiveness of the method. This four-probe thermal transport measurement method can lead to future discoveries of unique size-dependent thermal transport phenomena in nanostructures and low-dimensional materials, in addition to providing reliable experimental data for calibrating theoretical models

  3. Growth of uranyl hydroxide nanowires and nanotubes by the electrodeposition method and their transformation to one-dimensional U{sub 3}O{sub 8} nanostructures

    Wang, Lin; Zhao, Ran; Gu, Zhan-jun; Zhao, Yu-liang; Shi, Wei-qun [Key Laboratory of Nuclear Radiation and Nuclear Energy Technology and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); Chai, Zhi-fang [School of Radiological and Interdisciplinary Sciences, Soochow University, Suzhou (China)

    2014-03-15

    Actinide nanomaterials have great potential for application in the fabrication of nuclear fuels and spent fuel reprocessing in advanced nuclear energy systems. In this work, we used track-etched nanoporous membranes as hard templates to synthesize uranium-based nanomaterials with new structures by electrodeposition. Through electrochemical behavior investigations and subsequent product characterization, the chemical compositions of the deposition product has been confirmed to be uranyl hydroxide. More importantly, accurate control of the morphologies of the deposition product (i.e., nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and current density. The preferred morphology of the electrodeposition product was nanowires when a low current density was applied, whereas nanotubes could be formed only when a high current density and a short deposition time were both applied. The formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the overpotential electroreduction conditions. Additionally, we transformed the main chemical composition of the deposition products from uranyl hydroxide to triuranium octoxide by calcination, and SEM results showed that the morphologies of the nanowires and nanotubes were very well maintained after the calcination. Our work provides a useful protocol for the synthesis of one-dimensional uranium-based nanomaterials. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Growth of uranyl hydroxide nanowires and nanotubes by the electrodeposition method and their transformation to one-dimensional U3O8 nanostructures

    Wang, Lin; Zhao, Ran; Gu, Zhan-jun; Zhao, Yu-liang; Shi, Wei-qun; Chai, Zhi-fang

    2014-01-01

    Actinide nanomaterials have great potential for application in the fabrication of nuclear fuels and spent fuel reprocessing in advanced nuclear energy systems. In this work, we used track-etched nanoporous membranes as hard templates to synthesize uranium-based nanomaterials with new structures by electrodeposition. Through electrochemical behavior investigations and subsequent product characterization, the chemical compositions of the deposition product has been confirmed to be uranyl hydroxide. More importantly, accurate control of the morphologies of the deposition product (i.e., nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and current density. The preferred morphology of the electrodeposition product was nanowires when a low current density was applied, whereas nanotubes could be formed only when a high current density and a short deposition time were both applied. The formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the overpotential electroreduction conditions. Additionally, we transformed the main chemical composition of the deposition products from uranyl hydroxide to triuranium octoxide by calcination, and SEM results showed that the morphologies of the nanowires and nanotubes were very well maintained after the calcination. Our work provides a useful protocol for the synthesis of one-dimensional uranium-based nanomaterials. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Controlled Synthesis of Nanowire Assemblies by Ion-Track Template Electrodeposition

    Rauber, Markus

    2012-01-01

    The development of methods that allow the organization of nanostructures into integrated arrangements is crucial to realizing applications based on nanowires. Although various such methods exist, the direct synthesis of complex nanowire structures is one of the most suitable approaches for translating a large quantity of nanostructures into micro-/macroscale dimensions. In particular, three-dimensional (3-D) nanowire assemblies with a high integration level and adjustable connecti...

  6. Effect of Silicon Nanowire on Crystalline Silicon Solar Cell Characteristics

    Zahra Ostadmahmoodi Do; Tahereh Fanaei Sheikholeslami; Hassan Azarkish

    2016-01-01

    Nanowires (NWs) are recently used in several sensor or actuator devices to improve their ordered characteristics. Silicon nanowire (Si NW) is one of the most attractive one-dimensional nanostructures semiconductors because of its unique electrical and optical properties. In this paper, silicon nanowire (Si NW), is synthesized and characterized for application in photovoltaic device. Si NWs are prepared using wet chemical etching method which is commonly used as a simple and low cost method fo...

  7. Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

    Starko-Bowes, Ryan; Pramanik, Sandipan

    2013-01-01

    In recent years π-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication. A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently π-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important π-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors

  8. Superconductivity in nanowires

    Bezryadin, Alexey

    2012-01-01

    The importance and actuality of nanotechnology is unabated and will be for years to come. A main challenge is to understand the various properties of certain nanostructures, and how to generate structures with specific properties for use in actual applications in Electrical Engineering and Medicine.One of the most important structures are nanowires, in particular superconducting ones. They are highly promising for future electronics, transporting current without resistance and at scales of a few nanometers. To fabricate wires to certain defined standards however, is a major challenge, and so i

  9. Transformation of bulk alloys to oxide nanowires

    Lei, Danni; Benson, Jim; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

    2017-01-01

    One dimensional (1D) nanostructures offer prospects for enhancing the electrical, thermal, and mechanical properties of a broad range of functional materials and composites, but their synthesis methods are typically elaborate and expensive. We demonstrate a direct transformation of bulk materials into nanowires under ambient conditions without the use of catalysts or any external stimuli. The nanowires form via minimization of strain energy at the boundary of a chemical reaction front. We show the transformation of multimicrometer-sized particles of aluminum or magnesium alloys into alkoxide nanowires of tunable dimensions, which are converted into oxide nanowires upon heating in air. Fabricated separators based on aluminum oxide nanowires enhanced the safety and rate capabilities of lithium-ion batteries. The reported approach allows ultralow-cost scalable synthesis of 1D materials and membranes.

  10. Semiconductor Nanowires: What's Next?

    Yang, Peidong; Yan, Ruoxue; Fardy, Melissa

    2010-04-28

    In this perspective, we take a critical look at the research progress within the nanowire community for the past decade. We discuss issues on the discovery of fundamentally new phenomena versus performance benchmarking for many of the nanowire applications. We also notice that both the bottom-up and top-down approaches have played important roles in advancing our fundamental understanding of this new class of nanostructures. Finally we attempt to look into the future and offer our personal opinions on what the future trends will be in nanowire research.

  11. Metal chalcogenide nanostructures for renewable energy applications

    Qurashi, Ahsanulhaq

    2014-01-01

    This first ever reference book that focuses on metal chalcogenide semiconductor nanostructures for renewable energy applications encapsulates the state-of-the-art in multidisciplinary research on the metal chalcogenide semiconductor nanostructures (nanocrystals, nanoparticles, nanorods, nanowires,  nanobelts, nanoflowers, nanoribbons and more).  The properties and synthesis of a class of nanomaterials is essential to renewable energy manufacturing and this book focuses on the synthesis of metal chalcogendie nanostructures, their growth mechanism, optical, electrical, and other important prop

  12. Organic Nanowires

    Balzer, Frank; Schiek, Manuela; Al-Shamery, Katharina

    Single crystalline nanowires from fluorescing organic molecules like para-phenylenes or thiophenes are supposed to become key elements in future integrated optoelectronic devices [1]. For a sophisticated design of devices based on nanowires the basic principles of the nanowire formation have...... atomic force microscopy and from polarized far-field optical microscopy for various prototypical molecules are reproduced by electrostatic and Monte Carlo calculations. Based on the crystal structure, predictions on the growth habit from other conjugated molecules become in reach....

  13. Semiconducting silicon nanowires for biomedical applications

    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

  14. A hierarchical nanostructure consisting of amorphous MnO{sub 2}, Mn{sub 3}O{sub 4} nanocrystallites, and single-crystalline MnOOH nanowires for supercapacitors

    Hu, Chi-Chang; Hung, Ching-Yun [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu 30013 (China); Chang, Kuo-Hsin [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu 30013 (China); Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Yang, Yi-Lin [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China)

    2011-01-15

    In this communication, a porous hierarchical nanostructure consisting of amorphous MnO{sub 2} (a-MnO{sub 2}), Mn{sub 3}O{sub 4} nanocrystals, and single-crystalline MnOOH nanowires is designed for the supercapacitor application, which is prepared by a simple two-step electrochemical deposition process. Because of the gradual co-transformation of Mn{sub 3}O{sub 4} nanocrystals and a-MnO{sub 2} nanorods into an amorphous manganese oxide, the cycle stability of a-MnO{sub 2} is obviously enhanced by adding Mn{sub 3}O{sub 4}. This unique ternary oxide nanocomposite with 100-cycle CV activation exhibits excellent capacitive performances, i.e., excellent reversibility, high specific capacitances (470 F g{sup -1} in CaCl{sub 2}), high power property, and outstanding cycle stability. The highly porous microstructures of this composite before and after the 10,000-cycle CV test are examined by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). (author)

  15. Noncollinear magnetism in manganese nanostructures

    Zelený, Martin; Šob, Mojmír; Hafner, J.

    2009-01-01

    Roč. 80, č. 14 (2009), 144414/1-144414/19 ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100920; GA MŠk OC09011 Institutional research plan: CEZ:AV0Z20410507 Keywords : magnetism of nanostructures * nanowires * noncollinear magnetism * manganese Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  16. Failure mechanisms and electromechanical coupling in semiconducting nanowires

    Peng B.

    2010-06-01

    Full Text Available One dimensional nanostructures, like nanowires and nanotubes, are increasingly being researched for the development of next generation devices like logic gates, transistors, and solar cells. In particular, semiconducting nanowires with a nonsymmetric wurtzitic crystal structure, such as zinc oxide (ZnO and gallium nitride (GaN, have drawn immense research interests due to their electromechanical coupling. The designing of the future nanowire-based devices requires component-level characterization of individual nanowires. In this paper, we present a unique experimental set-up to characterize the mechanical and electromechanical behaviour of individual nanowires. Using this set-up and complementary atomistic simulations, mechanical properties of ZnO nanowires and electromechanical properties of GaN nanowires were investigated. In ZnO nanowires, elastic modulus was found to depend on nanowire diameter decreasing from 190 GPa to 140 GPa as the wire diameter increased from 5 nm to 80 nm. Inconsistent failure mechanisms were observed in ZnO nanowires. Experiments revealed a brittle fracture, whereas simulations using a pairwise potential predicted a phase transformation prior to failure. This inconsistency is addressed in detail from an experimental as well as computational perspective. Lastly, in addition to mechanical properties, preliminary results on the electromechanical properties of gallium nitride nanowires are also reported. Initial investigations reveal that the piezoresistive and piezoelectric behaviour of nanowires is different from bulk gallium nitride.

  17. Nanostructured layers of thermoelectric materials

    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.

  18. Topological insulator nanowires and nanowire hetero-junctions

    Deng, Haiming; Zhao, Lukas; Wade, Travis; Konczykowski, Marcin; Krusin-Elbaum, Lia

    2014-03-01

    The existing topological insulator materials (TIs) continue to present a number of challenges to complete understanding of the physics of topological spin-helical Dirac surface conduction channels, owing to a relatively large charge conduction in the bulk. One way to reduce the bulk contribution and to increase surface-to-volume ratio is by nanostructuring. Here we report on the synthesis and characterization of Sb2Te3, Bi2Te3 nanowires and nanotubes and Sb2Te3/Bi2Te3 heterojunctions electrochemically grown in porous anodic aluminum oxide (AAO) membranes with varied (from 50 to 150 nm) pore diameters. Stoichiometric rigid polycrystalline nanowires with controllable cross-sections were obtained using cell voltages in the 30 - 150 mV range. Transport measurements in up to 14 T magnetic fields applied along the nanowires show Aharonov-Bohm (A-B) quantum oscillations with periods corresponding to the nanowire diameters. All nanowires were found to exhibit sharp weak anti-localization (WAL) cusps, a characteristic signature of TIs. In addition to A-B oscillations, new quantization plateaus in magnetoresistance (MR) at low fields (< 0 . 7T) were observed. The analysis of MR as well as I - V characteristics of heterojunctions will be presented. Supported in part by NSF-DMR-1122594, NSF-DMR-1312483-MWN, and DOD-W911NF-13-1-0159.

  19. A novel rotating electrochemically anodizing process to fabricate titanium oxide surface nanostructures enhancing the bioactivity of osteoblastic cells.

    Chang, Chih-Hung; Lee, Hsin-Chun; Chen, Chia-Chun; Wu, Yi-Hau; Hsu, Yuan-Ming; Chang, Yin-Pen; Yang, Ta-I; Fang, Hsu-Wei

    2012-07-01

    Titanium oxide (TiO(2) ) surface layers with various surface nanostructures (nanotubes and nanowires) have been developed using an anodizing technique. The pore size and length of TiO(2) nanotubes can be tailored by changing the anodizing time and applied voltage. We developed a novel method to transform the upper part of the formed TiO(2) nanotubes into a nanowire-like structure by rotating the titanium anode during anodizing process. The transformation of nanotubes contributed to the preferential chemical dissolution of TiO(2) on the areas with intense interface tension stress. Furthermore, we further compared the effect of various TiO(2) surface nanostructures including flat, nanotubes, and nanowires on bioactive applications. The MG-63 osteoblastic cells cultured on the TiO(2) nanowires exhibited a polygonal shape with extending filopodia and showed highest levels of cell viability and alkaline phosphatase activity (ALP). The TiO(2) nanowire structure formed by our novel method can provide beneficial effects for MG-63 osteoblastic cells in attachment, proliferation, and secretion of ALP on the TiO(2) surface layer. Copyright © 2012 Wiley Periodicals, Inc.

  20. Lead-free LiNbO3 nanowire-based nanocomposite for piezoelectric power generation

    2014-01-01

    In a flexible nanocomposite-based nanogenerator, in which piezoelectric nanostructures are mixed with polymers, important parameters to increase the output power include using long nanowires with high piezoelectricity and decreasing the dielectric constant of the nanocomposite. Here, we report on piezoelectric power generation from a lead-free LiNbO3 nanowire-based nanocomposite. Through ion exchange of ultra-long Na2Nb2O6-H2O nanowires, we synthesized long (approximately 50 μm in length) single-crystalline LiNbO3 nanowires having a high piezoelectric coefficient (d33 approximately 25 pmV-1). By blending LiNbO3 nanowires with poly(dimethylsiloxane) (PDMS) polymer (volume ratio 1:100), we fabricated a flexible nanocomposite nanogenerator having a low dielectric constant (approximately 2.7). The nanogenerator generated stable electric power, even under excessive strain conditions (approximately 105 cycles). The different piezoelectric coefficients of d33 and d31 for LiNbO3 may have resulted in generated voltage and current for the e33 geometry that were 20 and 100 times larger than those for the e31 geometry, respectively. This study suggests the importance of the blending ratio and strain geometry for higher output-power generation in a piezoelectric nanocomposite-based nanogenerator. PACS 77.65.-j; 77.84.-s; 73.21.Hb PMID:24386884

  1. ZnO Nanowires Synthesized by Vapor Phase Transport Deposition on Transparent Oxide Substrates

    Taylor Curtis

    2010-01-01

    Full Text Available Abstract Zinc oxide nanowires have been synthesized without using metal catalyst seed layers on fluorine-doped tin oxide (FTO substrates by a modified vapor phase transport deposition process using a double-tube reactor. The unique reactor configuration creates a Zn-rich vapor environment that facilitates formation and growth of zinc oxide nanoparticles and wires (20–80 nm in diameter, up to 6 μm in length, density <40 nm apart at substrate temperatures down to 300°C. Electron microscopy and other characterization techniques show nanowires with distinct morphologies when grown under different conditions. The effect of reaction parameters including reaction time, temperature, and carrier gas flow rate on the size, morphology, crystalline structure, and density of ZnO nanowires has been investigated. The nanowires grown by this method have a diameter, length, and density appropriate for use in fabricating hybrid polymer/metal oxide nanostructure solar cells. For example, it is preferable to have nanowires no more than 40 nm apart to minimize exciton recombination in polymer solar cells.

  2. Nanostructures from nanoparticles

    Mendes, Paula M; Chen Yu; Palmer, Richard E; Nikitin, Kirill; Fitzmaurice, Donald; Preece, Jon A

    2003-01-01

    This paper reviews recent experimental approaches to the development of surface nanostructures from nanoparticles. The formation of nanowires by electron beam writing in films of gold nanoparticles passivated with a specially designed class of ligand molecules (dialkyl sulfides) is presented, together with illustrations of practical nanostructures. Potential applications of this methodology are discussed. Another alternative to the controlled fabrication of arrays of nanoparticles, based on nanocrystals which contain molecular recognition elements in the ligand shell, is also surveyed. These particles aggregate in the presence of specifically designed molecular dications which act as a molecular binder. Finally, recent work on the formation of nanoscale surface architectures using x-ray patterning of self-assembled monolayers is introduced. Current and potential future applications of these surface nanostructures are discussed

  3. Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

    Chen, Ye; Khashab, Niveen M.; Tao, Jing

    2017-01-01

    Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets

  4. Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

    Chen, Ye

    2017-01-26

    Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets. The composition has high conductivity and flexibility. The composition can be made by a one-pot synthesis in which a graphene material precursor is converted to the graphene material, and the metal precursor is converted to the metal. A reducing solvent or dispersant such as NMP can be used. Devices made from the composition include a pressure sensor which has high sensitivity. Two two- dimension materials can be combined to form a hybrid material.

  5. Controllable one-pot synthesis of various one-dimensional Bi2S3 nanostructures and their enhanced visible-light-driven photocatalytic reduction of Cr(VI)

    Hu, Enlai; Gao, Xuehui; Etogo, Atangana; Xie, Yunlong; Zhong, Yijun; Hu, Yong

    2014-01-01

    Highlights: • 1D Bi 2 S 3 nanostructures were prepared by a facile ethanol-assisted one-pot reaction. • The size and morphology of the products can be conveniently varied. • The sulfur source plays a crucial role in determining the morphologies of products. • 1D Bi 2 S 3 nanostructures exhibit enhanced photocatalytic reduction of Cr(VI). • Bi 2 S 3 nanowires exhibit the highest photoreduction activity among three samples. - Abstract: One-dimensional (1D) Bi 2 S 3 nanostructures with various morphologies, including nanowires, nanorods, and nanotubes, have been successfully synthesized through a facile ethanol-assisted one-pot reaction. It is found that the size, morphology and structure of the products can be conveniently varied or controlled by simply adjusting the volume ratio of ethanol and water in the reaction system. Further experimental results indicate that sulfur source also plays the other crucial role in determining the product morphology. The synthetic strategy developed in this work is highly efficient in producing 1D Bi 2 S 3 nanostructures with high quality and large quantity. Photocatalysis experiments show the as-prepared 1D Bi 2 S 3 nanostructures possess significantly enhanced photocatalytic reduction of Cr(VI) when exposed to visible light irradiation. Especially, Bi 2 S 3 nanowires exhibit the highest photocatalytic activity and can be used repeatedly after washed with dilute HCl

  6. Zinc oxide nanostructures: new properties for advances applications

    Lupan, Oleg; Chow, Lee; Pauporte, Thierry

    2011-01-01

    Zinc oxide is a material which exhibits a variety of new properties at nanometer dimensions. Various synthesis techniques have been carried out to provide growth of nanowires, nanorods, nanorings, nanosprings, and nanobelts of ZnO under various conditions. These nanostructures show that ZnO possesses probably the richest family of nanoarchitectures among all materials, including their structures and properties. Such nanoarchitectures are potential building blocks for novel applications in optoelectronics, sensors, photovoltaic and nano-biomedical sciences. This work presents a review of various nano architectures of ZnO grown by the electrochemical, hydrothermal and solid-vapor phase techniques and their properties. The possible applications of ZnO nanowires as sensors, nano-DSSC, photodetectors and nano-LEDs will be presented.

  7. Quantification of nanowire uptake by live cells

    Margineanu, Michael B.

    2015-05-01

    Nanostructures fabricated by different methods have become increasingly important for various applications at the cellular level. In order to understand how these nanostructures “behave” and for studying their internalization kinetics, several attempts have been made at tagging and investigating their interaction with living cells. In this study, magnetic iron nanowires with an iron oxide layer are coated with (3-Aminopropyl)triethoxysilane (APTES), and subsequently labeled with a fluorogenic pH-dependent dye pHrodo™ Red, covalently bound to the aminosilane surface. Time-lapse live imaging of human colon carcinoma HCT 116 cells interacting with the labeled iron nanowires is performed for 24 hours. As the pHrodo™ Red conjugated nanowires are non-fluorescent outside the cells but fluoresce brightly inside, internalized nanowires are distinguished from non-internalized ones and their behavior inside the cells can be tracked for the respective time length. A machine learning-based computational framework dedicated to automatic analysis of live cell imaging data, Cell Cognition, is adapted and used to classify cells with internalized and non-internalized nanowires and subsequently determine the uptake percentage by cells at different time points. An uptake of 85 % by HCT 116 cells is observed after 24 hours incubation at NW-to-cell ratios of 200. While the approach of using pHrodo™ Red for internalization studies is not novel in the literature, this study reports for the first time the utilization of a machine-learning based time-resolved automatic analysis pipeline for quantification of nanowire uptake by cells. This pipeline has also been used for comparison studies with nickel nanowires coated with APTES and labeled with pHrodo™ Red, and another cell line derived from the cervix carcinoma, HeLa. It has thus the potential to be used for studying the interaction of different types of nanostructures with potentially any live cell types.

  8. Synthesis of SERS active Au nanowires in different noncoordinating solvents

    Hou Xiaomiao; Zhang Xiaoling, E-mail: zhangxl@bit.edu.cn [Key Laboratory of Cluster Science of Ministry of Education, Beijing Institute of Technology, Department of Chemistry, School of Science (China); Fang Yan, E-mail: fangyan@mail.cnu.edu.cn [Beijing Key Laboratory for Nano-Photonics and Nano-Structure (NPNS), Capital Normal University (China); Chen Shutang; Li Na; Zhou Qi [Key Laboratory of Cluster Science of Ministry of Education, Beijing Institute of Technology, Department of Chemistry, School of Science (China)

    2011-06-15

    Au nanowires with length up to micrometers were synthesized through a simple and one-pot solution growth method. HAuCl{sub 4} was reduced in a micellar structure formed by 1-octadecylamine and oleic acid in hexane, heptane, toluene and chloroform, respectively. As the non-polarity of noncoordinating solvents can affect the nucleation and growth rates of Au nanostructures, Au nanowires with different diameters could be obtained by changing the noncoordinating solvents in the synthetic process. The influences of the solvents on the morphology of Au nanowires were systematically studied. When using hexane as reaction solvent, the product turned to be high portion of Au nanowires with more uniform size than the others. Furthermore, surface-enhanced Raman scattering (SERS) spectrum of 2-thionaphthol was obtained on the Au nanowire-modified substrate, indicating that the as-synthesized Au nanowires have potential for highly sensitive optical detection application.

  9. Methods for synthesizing metal oxide nanowires

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  10. Nanowire Lasers

    Couteau C.

    2015-05-01

    Full Text Available We review principles and trends in the use of semiconductor nanowires as gain media for stimulated emission and lasing. Semiconductor nanowires have recently been widely studied for use in integrated optoelectronic devices, such as light-emitting diodes (LEDs, solar cells, and transistors. Intensive research has also been conducted in the use of nanowires for subwavelength laser systems that take advantage of their quasione- dimensional (1D nature, flexibility in material choice and combination, and intrinsic optoelectronic properties. First, we provide an overview on using quasi-1D nanowire systems to realize subwavelength lasers with efficient, directional, and low-threshold emission. We then describe the state of the art for nanowire lasers in terms of materials, geometry, andwavelength tunability.Next,we present the basics of lasing in semiconductor nanowires, define the key parameters for stimulated emission, and introduce the properties of nanowires. We then review advanced nanowire laser designs from the literature. Finally, we present interesting perspectives for low-threshold nanoscale light sources and optical interconnects. We intend to illustrate the potential of nanolasers inmany applications, such as nanophotonic devices that integrate electronics and photonics for next-generation optoelectronic devices. For instance, these building blocks for nanoscale photonics can be used for data storage and biomedical applications when coupled to on-chip characterization tools. These nanoscale monochromatic laser light sources promise breakthroughs in nanophotonics, as they can operate at room temperature, can potentially be electrically driven, and can yield a better understanding of intrinsic nanomaterial properties and surface-state effects in lowdimensional semiconductor systems.

  11. Nanostructured Semiconductor Electrodes for Solar Energy Conversion and Innovations in Undergraduate Chemical Lab Curriculum

    Lee, Sudarat

    This dissertation presents the methodology and discussion of preparing nanostructured, high aspect ratio p-type phosphide-based binary and ternary semiconductors via "top-down" anodic etching, a process which creates nanostructures from a large parent entity, and "bottom-up" vapor-liquid-solid growth, a mechanism which builds up small clusters of molecules block-by-block. Such architecture is particularly useful for semiconducting materials with incompatible optical absorption depth and charge carrier diffusion length, as it not only relaxes the requirement for high-grade crystalline materials, but also increases the carrier collection efficiencies for photons with energy greater than or equal to the band gap. The main focus of this dissertation is to obtain nanostructured p-type phosphide semiconductors for photoelectrochemical (PEC) cell applications. Chapter II in the thesis describes a methodology for creating high-aspect ratio p-GaP that function as a photocathode under white light illumination. Gallium phosphide (GaP, band gap: 2.26 eV) is a suitable candidate for solar conversion and energy storage due to its ability to generate large photocurrent and photovoltage to drive fuel-forming reactions. Furthermore, the band edge positions of GaP can provide sufficient kinetics for the reduction of protons and carbon dioxide. The structure is prepared by anodic etching, and the resulting macroporous structures are subsequently doped with Zn by thermally driving in Zn from conformal ZnO films prepared by atomic layer deposition (ALD). The key finding of this work is a viable doping strategy involving ALD ZnO films for making functioning p-type GaP nanostructures. Chapter III compares the GaP nanowires grown from gold (Au) and tin (Sn) VLS catalysts in a benign solid sublimation growth scheme in terms of crystal structure and photoactivity. Sn is less noble than Au, allowing complete removal of Sn metal catalysts from the nanowires through wet chemical etching which

  12. Transport and structural characterization of solution-processable doped ZnO nanowires

    Noriega, Rodrigo; Goris, Ludwig; Rivnay, Jonathan; Scholl, Jonathan; Thompson, Linda M.; Palke, Aaron C.; Stebbins, Jonathan F.; Salleo, Alberto

    2009-01-01

    The use of ZnO nanowires has become a widespread topic of interest in optoelectronics. In order to correctly assess the quality, functionality, and possible applications of such nanostructures it is important to accurately understand

  13. Magnetic nanowires and hyperthermia: How geometry and material affect heat production efficiency

    Contreras, Maria F.; Zaher, A.; Perez, Jose E.; Ravasi, Timothy; Kosel, Jü rgen

    2015-01-01

    Magnetic hyperthermia, which refers to the production of heat by magnetic nanostructures under an alternating magnetic field (AMF), has been previously investigated with superparamagnetic nanobeads as a cancer therapy method. Magnetic nanowires (NWs

  14. Present and future applications of magnetic nanostructures grown by FEBID

    Teresa, J.M. de [CSIC-Universidad de Zaragoza, Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Aragon (ICMA), Saragossa (Spain); Universidad de Zaragoza, Laboratorio de Microscopias Avanzadas (LMA), Instituto de Nanociencia de Aragon (INA), Saragossa (Spain); Fernandez-Pacheco, A. [University of Cambridge, TFM Group, Cavendish Laboratory, Cambridge (United Kingdom)

    2014-12-15

    Currently, magnetic nanostructures are routinely grown by focused electron beam induced deposition (FEBID). In the present article, we review the milestones produced in the topic in the past as well as the future applications of this technology. Regarding past milestones, we highlight the achievement of high-purity cobalt and iron deposits, the high lateral resolution obtained, the growth of 3D magnetic deposits, the exploration of magnetic alloys and the application of magnetic deposits for Hall sensing and in domain-wall conduit and magnetologic devices. With respect to future perspectives of the topic, we emphasize the potential role of magnetic nanostructures grown by FEBID for applications related to highly integrated 2D arrays, 3D nanowires devices, fabrication of advanced scanning-probe systems, basic studies of magnetic structures and their dynamics, small sensors (including biosensors) and new applications brought by magnetic alloys and even exchange biased systems. (orig.)

  15. Piezoelectric properties of zinc oxide nanowires: an ab initio study.

    Korir, K K; Cicero, G; Catellani, A

    2013-11-29

    Nanowires made of materials with non-centrosymmetric crystal structures are expected to be ideal building blocks for self-powered nanodevices due to their piezoelectric properties, yet a controversial explanation of the effective operational mechanisms and size effects still delays their real exploitation. To solve this controversy, we propose a methodology based on DFT calculations of the response of nanostructures to external deformations that allows us to distinguish between the different (bulk and surface) contributions: we apply this scheme to evaluate the piezoelectric properties of ZnO [0001] nanowires, with a diameter up to 2.3 nm. Our results reveal that, while surface and confinement effects are negligible, effective strain energies, and thus the nanowire mechanical response, are dependent on size. Our unified approach allows for a proper definition of piezoelectric coefficients for nanostructures, and explains in a rigorous way the reason why nanowires are found to be more sensitive to mechanical deformation than the corresponding bulk material.

  16. Evaporation phase change processes of water/methanol mixtures on superhydrophobic nanostructured surfaces

    Chiang, Cheng-Kun; Lu, Yen-Wen

    2011-07-01

    Evaporation phenomena are a critical and frequently seen phase change process in many heat transfer applications. In this paper, we study the evaporation process of a sessile droplet on two topologically different surfaces, including smooth and nanostructured surfaces. The nanostructured surface has an array of high-aspect-ratio nanowires (height/diameter ~ 125) and is implemented by using a simple template-based nanofabrication method. It possesses superhydrophobicity (>140°) and low contact angle hysteresis (1.2-2.1°), allowing the liquid droplets to remain in the 'fakir' state throughout the evaporation processes. Sessile droplets of deionized (DI) water and water/methanol binary mixture test liquids with their contact angles and base diameters are monitored. The results show that the nanostructures play a critical role in the droplet dynamics during evaporation.

  17. Evaporation phase change processes of water/methanol mixtures on superhydrophobic nanostructured surfaces

    Chiang, Cheng-Kun; Lu, Yen-Wen

    2011-01-01

    Evaporation phenomena are a critical and frequently seen phase change process in many heat transfer applications. In this paper, we study the evaporation process of a sessile droplet on two topologically different surfaces, including smooth and nanostructured surfaces. The nanostructured surface has an array of high-aspect-ratio nanowires (height/diameter ∼ 125) and is implemented by using a simple template-based nanofabrication method. It possesses superhydrophobicity (>140°) and low contact angle hysteresis (1.2–2.1°), allowing the liquid droplets to remain in the 'fakir' state throughout the evaporation processes. Sessile droplets of deionized (DI) water and water/methanol binary mixture test liquids with their contact angles and base diameters are monitored. The results show that the nanostructures play a critical role in the droplet dynamics during evaporation

  18. Synthesis and Application of One-Dimensional La(OH3 Nanostructures: An Overview

    Xiang Xiao

    2014-01-01

    Full Text Available One-dimensional (1D semiconductor nanomaterials are of particular importance owing to their unique properties and potential applications. This review attempts to provide a comprehensive introduction of 1D La(OH3 nanostructures including nanowires, nanoneedles, nanobelts, and nanorods. Firstly, various strategies developed to fabricate the 1D La(OH3 nanostructures are discussed, such as precipitation and composite-hydroxide-mediated, hydrothermal, and solvothermal methods, accompanying the description of the corresponding growth mechanisms. Then, the unique properties such as novel physical properties of 1D La(OH3 nanostructures resulting from their unique electronic structures and numerous transition modes involving the 4f shells of these ions are represented in detail. Also, the wide applications in photocatalyst, capacitors, and photoluminescence based on the unique properties are discussed. Finally, the paper ends with a summary and some perspectives on the challenges and new directions in this emerging area.

  19. Si nanoparticle-decorated Si nanowire networks for Li-ion battery anodes

    Hu, Liangbing

    2011-01-01

    We designed and fabricated binder-free, 3D porous silicon nanostructures for Li-ion battery anodes, where Si nanoparticles electrically contact current collectors via vertically grown silicon nanowires. When compared with a Si nanowire anode, the areal capacity was increased by a factor of 4 without having to use long, high temperature steps under vacuum that vapour-liquid-solid Si nanowire growth entails. © 2011 The Royal Society of Chemistry.

  20. FDTD modeling of solar energy absorption in silicon branched nanowires.

    Lundgren, Christin; Lopez, Rene; Redwing, Joan; Melde, Kathleen

    2013-05-06

    Thin film nanostructured photovoltaic cells are increasing in efficiency and decreasing the cost of solar energy. FDTD modeling of branched nanowire 'forests' are shown to have improved optical absorption in the visible and near-IR spectra over nanowire arrays alone, with a factor of 5 enhancement available at 1000 nm. Alternate BNW tree configurations are presented, achieving a maximum absorption of over 95% at 500 nm.

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

    Castillo, Jaime

    2015-01-01

    the advantages of diphenylalanine are explained step by step offering new alternatives to fabricate nanostructures in a simple and rapid way. The chapter is complemented with techniques to manipulate the self-assembled diphenylalanine nanostructures without changing its properties during the manipulation process.......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...

  2. Nanoconstruction by welding individual metallic nanowires together using nanoscale solder

    Peng, Y; Inkson, B J; Cullis, A G

    2010-01-01

    This work presents a new bottom-up nanowelding technique enabling building blocks to be assembled and welded together into complex 3D nanostructures using nanovolumes of metal solder. The building blocks of gold nanowires, (Co 72 Pt 28 /Pt) n multilayer nanowires, and nanosolder Sn 99 Au 1 alloy nanowires were successfully fabricated by a template technique. Individual metallic nanowires were picked up and assembled together. Conductive nanocircuits were then welded together using similar or dissimilar nanosolder material. At the weld sites, nanoscale volumes of a chosen metal are deposited using nanosolder of a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their structural integrity. The whole nanowelding process is clean, controllable and reliable, and ensures both mechanically strong and electrically conductive contacts.

  3. Contact materials for nanowire devices and nanoelectromechanical switches

    Hussain, Muhammad Mustafa

    2011-02-01

    The impact of contact materials on the performance of nanostructured devices is expected to be signifi cant. This is especially true since size scaling can increase the contact resistance and induce many unseen phenomenon and reactions that greatly impact device performance. Nanowire and nanoelectromechanical switches are two emerging nanoelectronic devices. Nanowires provide a unique opportunity to control the property of a material at an ultra-scaled dimension, whereas a nanoelectromechanical switch presents zero power consumption in its off state, as it is physically detached from the sensor anode. In this article, we specifi cally discuss contact material issues related to nanowire devices and nanoelectromechanical switches.

  4. Study of Growth Kinetics in One Dimensional and Two Dimensional ZnO Nanostructures

    Yin, Xin

    Because of the merits arising from the unique geometry, nanostructure materials have been an essential class of materials, which have shown great potentials in the fields of electronics, photonics, and biology. With various nanostructures being intensively investigated and successfully complemented into device applications, there has been one increasing demand to the investigation of the growth mechanism devoted to the controlled nanostructure synthesis. Motivated by this situation, this thesis is focused on the fundamental understanding of the nanostructure growth. Specifically, by taking zinc oxide as an example material, through controlling the basic driving force, that is, the supersaturation, I have rationally designed and synthesized various of nanostructures, and further applied the classical layer-by-layer growth mechanism to the understanding on the formation of these nanostructures, they are, the convex-plate-capped nanowires, the concave-plate-capped nanowires, the facet evolution at the tip of the nanowires, and the ultrathin 2D nanosheets.

  5. Hierarchical Assembly of Multifunctional Oxide-based Composite Nanostructures for Energy and Environmental Applications

    Hui-Jan Lin

    2012-06-01

    Full Text Available Composite nanoarchitectures represent a class of nanostructured entities that integrates various dissimilar nanoscale building blocks including nanoparticles, nanowires, and nanofilms toward realizing multifunctional characteristics. A broad array of composite nanoarchitectures can be designed and fabricated, involving generic materials such as metal, ceramics, and polymers in nanoscale form. In this review, we will highlight the latest progress on composite nanostructures in our research group, particularly on various metal oxides including binary semiconductors, ABO3-type perovskites, A2BO4 spinels and quaternary dielectric hydroxyl metal oxides (AB(OH6 with diverse application potential. Through a generic template strategy in conjunction with various synthetic approaches—such as hydrothermal decomposition, colloidal deposition, physical sputtering, thermal decomposition and thermal oxidation, semiconductor oxide alloy nanowires, metal oxide/perovskite (spinel composite nanowires, stannate based nanocompostes, as well as semiconductor heterojunction—arrays and networks have been self-assembled in large scale and are being developed as promising classes of composite nanoarchitectures, which may open a new array of advanced nanotechnologies in solid state lighting, solar absorption, photocatalysis and battery, auto-emission control, and chemical sensing.

  6. Towards highly sensitive strain sensing based on nanostructured materials

    Dao, Dzung Viet; Nakamura, Koichi; Sugiyama, Susumu; Bui, Tung Thanh; Dau, Van Thanh; Yamada, Takeo; Hata, Kenji

    2010-01-01

    This paper presents our recent theoretical and experimental study of piezo-effects in nanostructured materials for highly sensitive, high resolution mechanical sensors. The piezo-effects presented here include the piezoresistive effect in a silicon nanowire (SiNW) and single wall carbon nanotube (SWCNT) thin film, as well as the piezo-optic effect in a Si photonic crystal (PhC) nanocavity. Firstly, the electronic energy band structure of the silicon nanostructure is discussed and simulated by using the First-Principles Calculations method. The result showed a remarkably different energy band structure compared with that of bulk silicon. This difference in the electronic state will result in different physical, chemical, and therefore, sensing properties of silicon nanostructures. The piezoresistive effects of SiNW and SWCNT thin film were investigated experimentally. We found that, when the width of ( 110 ) p-type SiNW decreases from 500 to 35 nm, the piezoresistive effect increases by more than 60%. The longitudinal piezoresistive coefficient of SWCNT thin film was measured to be twice that of bulk p-type silicon. Finally, theoretical investigations of the piezo-optic effect in a PhC nanocavity based on Finite Difference Time Domain (FDTD) showed extremely high resolution strain sensing. These nanostructures were fabricated based on top-down nanofabrication technology. The achievements of this work are significant for highly sensitive, high resolution and miniaturized mechanical sensors

  7. Semiconductor nanostructures for artificial photosynthesis

    Yang, Peidong

    2012-02-01

    Nanowires, with their unique capability to bridge the nanoscopic and macroscopic worlds, have already been demonstrated as important materials for different energy conversion. One emerging and exciting direction is their application for solar to fuel conversion. The generation of fuels by the direct conversion of solar energy in a fully integrated system is an attractive goal, but no such system has been demonstrated that shows the required efficiency, is sufficiently durable, or can be manufactured at reasonable cost. One of the most critical issues in solar water splitting is the development of a suitable photoanode with high efficiency and long-term durability in an aqueous environment. Semiconductor nanowires represent an important class of nanostructure building block for direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. Nanowires can be readily designed and synthesized to deterministically incorporate heterojunctions with improved light absorption, charge separation and vectorial transport. Meanwhile, it is also possible to selectively decorate different oxidation or reduction catalysts onto specific segments of the nanowires to mimic the compartmentalized reactions in natural photosynthesis. In this talk, I will highlight several recent examples in this lab using semiconductor nanowires and their heterostructures for the purpose of direct solar water splitting.

  8. The physics of semiconductors an introduction including nanophysics and applications

    Grundmann, Marius

    2016-01-01

    The 3rd edition of this successful textbook contains ample material for a comprehensive upper-level undergraduate or beginning graduate course, guiding readers to the point where they can choose a special topic and begin supervised research. The textbook provides a balance between essential aspects of solid-state and semiconductor physics, on the one hand, and the principles of various semiconductor devices and their applications in electronic and photonic devices, on the other. It highlights many practical aspects of semiconductors such as alloys, strain, heterostructures, nanostructures, that are necessary in modern semiconductor research but typically omitted in textbooks. Coverage also includes additional advanced topics, such as Bragg mirrors, resonators, polarized and magnetic semiconductors, nanowires, quantum dots, multi-junction solar cells, thin film transistors, carbon-based nanostructures and transparent conductive oxides. The text derives explicit formulas for many results to support better under...

  9. Electrodeposition of rhenium-tin nanowires

    Naor-Pomerantz, Adi; Eliaz, Noam; Gileadi, Eliezer

    2011-01-01

    Highlights: → Rhenium-tin nanowires were formed electrochemically, without using a template. → The nanowires consisted of a crystalline-Sn-core/amorphous-Re-shell structure. → The effects of bath composition and operating conditions were investigated. → A mechanism is suggested for the formation of the core/shell structure. → The nanowires may be attractive for a variety of applications. - Abstract: Rhenium (Re) is a refractory metal which exhibits an extraordinary combination of properties. Thus, nanowires and other nanostructures of Re-alloys may possess unique properties resulting from both Re chemistry and the nanometer scale, and become attractive for a variety of applications, such as in catalysis, photovoltaic cells, and microelectronics. Rhenium-tin coatings, consisting of nanowires with a core/shell structure, were electrodeposited on copper substrates under galvanostatic or potentiostatic conditions. The effects of bath composition and operating conditions were investigated, and the chemistry and structure of the coatings were studied by a variety of analytical tools. A Re-content as high as 77 at.% or a Faradaic efficiency as high as 46% were attained. Ranges of Sn-to-Re in the plating bath, applied current density and applied potential, within which the nanowires could be formed, were determined. A mechanism was suggested, according to which Sn nanowires were first grown on top of Sn micro-particles, and then the Sn nanowires reduced the perrhenate chemically, thus forming a core made of crystalline Sn-rich phase, and a shell made of amorphous Re-rich phase. The absence of mutual solubility of Re and Sn may be the driving force for this phase separation.

  10. Copper Nanowire Production for Interconnect Applications

    Han, Jin-Woo (Inventor); Meyyappan, Meyya (Inventor)

    2014-01-01

    A method of fabricating metallic Cu nanowires with lengths up to about 25 micrometers and diameters in a range 20-100 nanometers, or greater if desired. Vertically oriented or laterally oriented copper oxide structures (CuO and/or Cu2O) are grown on a Cu substrate. The copper oxide structures are reduced with 99+ percent H or H2, and in this reduction process the lengths decrease (to no more than about 25 micrometers), the density of surviving nanostructures on a substrate decreases, and the diameters of the surviving nanostructures have a range, of about 20-100 nanometers. The resulting nanowires are substantially pure Cu and can be oriented laterally (for local or global interconnects) or can be oriented vertically (for standard vertical interconnects).

  11. Nanostructures for Organic Solar Cells

    Goszczak, Arkadiusz Jarosław

    2016-01-01

    The experimental work in this thesis is focused on the fabrication of nanostructures that can be implemented in organic solar cell (OSC) architecture for enhancement of the device performance. Solar devices made from organic material are gaining increased attention, compared to their inorganic...... counterparts, due to the promising advantages, such as transparency, flexibility, ease of processing etc. But their efficiencies cannot be compared to the inorganic ones. Boosting the efficiency of OSCs by nanopatterning has thus been puzzling many researchers within the past years. Therefore various methods...... have been proposed to be used for developing efficient nanostructures for OSC devices such as, plasmonic structures, nanowires (NWs), gratings, nanorods etc. The nanostructuring methods applied though, do not offer the possibility of a cheap, rapid, reproducible and scalable fabrication. It is the aim...

  12. Localized synthesis, assembly and integration of silicon nanowires

    Englander, Ongi

    Localized synthesis, assembly and integration of one-dimensional silicon nanowires with MEMS structures is demonstrated and characterized in terms of local synthesis processes, electric-field assisted self-assembly, and a proof-of-concept nanoelectromechanical system (HEMS) demonstration. Emphasis is placed on the ease of integration, process control strategies, characterization techniques and the pursuit of integrated devices. A top-down followed by a bottom-up integration approach is utilized. Simple MEMS heater structures are utilized as the microscale platforms for the localized, bottom-up synthesis of one-dimensional nanostructures. Localized heating confines the high temperature region permitting only localized nanostructure synthesis and allowing the surroundings to remain at room temperature thus enabling CMOS compatible post-processing. The vapor-liquid-solid (VLS) process in the presence of a catalytic nanoparticle, a vapor phase reactant, and a specific temperature environment is successfully employed locally. Experimentally, a 5nm thick gold-palladium layer is used as the catalyst while silane is the vapor phase reactant. The current-voltage behavior of the MEMS structures can be correlated to the approximate temperature range required for the VLS reaction to take place. Silicon nanowires averaging 45nm in diameter and up to 29mum in length synthesized at growth rates of up to 1.5mum/min result. By placing two MEMS structures in close proximity, 4--10mum apart, localized silicon nanowire growth can be used to link together MEMS structures to yield a two-terminal, self-assembled micro-to-nano system. Here, one MEMS structure is designated as the hot growth structure while a nearby structure is designated as the cold secondary structure, whose role is to provide a natural stopping point for the VLS reaction. The application of a localized electric-field, 5 to 13V/mum in strength, during the synthesis process, has been shown to improve nanowire

  13. A simple method of growing silver chloride nanocubes on silver nanowires

    Khaligh, Hadi Hosseinzadeh; Goldthorpe, Irene A

    2015-01-01

    The growth of AgCl nanocubes directly on the sidewalls of Ag nanowires is demonstrated. The nanocubes can be simply obtained through extended low temperature annealing of polyol-synthesized silver nanowires in a vacuum. The length of time and temperature of the anneal and the diameter of the nanowire affect the size and density of the nanocubes obtained. It is hypothesized that the AgCl material is supplied from reactants leftover from the silver nanowire synthesis. This novel hybrid nanostructure may have applications in areas such as photovoltaics, surface enhanced Raman spectroscopy, and photocatalysis. (fast track communication)

  14. A simple method of growing silver chloride nanocubes on silver nanowires

    Hosseinzadeh Khaligh, Hadi; Goldthorpe, Irene A.

    2015-09-01

    The growth of AgCl nanocubes directly on the sidewalls of Ag nanowires is demonstrated. The nanocubes can be simply obtained through extended low temperature annealing of polyol-synthesized silver nanowires in a vacuum. The length of time and temperature of the anneal and the diameter of the nanowire affect the size and density of the nanocubes obtained. It is hypothesized that the AgCl material is supplied from reactants leftover from the silver nanowire synthesis. This novel hybrid nanostructure may have applications in areas such as photovoltaics, surface enhanced Raman spectroscopy, and photocatalysis.

  15. Facile synthesis of polypyrrole nanowires for high-performance supercapacitor electrode materials

    Zhao, Junhong; Wu, Jinping; Li, Bing; Du, Weimin; Huang, Qingli; Zheng, Mingbo; Xue, Huaiguo; Pang, Huan

    2016-01-01

    Polypyrrole nanowires are facile synthesized under a mild condition with FeCl3 as an oxidant. Polypyrrole nanowires with the width of 120 nm form many nanogaps or pores due to the intertwined nanostructures. More importantly, PPy nanowires were further applied for supercapacitor electrode materials. After electrochemical testing, it was observed that the PPy nanowire based electrode showed a large specific capacitance (420 F g−1, 1.5 A g−1) and good rate capability (272 F g−1, 18.0 A g−1), wh...

  16. Simulation study of dielectrophoretic assembly of nanowire between electrode pairs

    Tao, Quan, E-mail: taq3@pitt.edu; Lan, Fei; Jiang, Minlin [University of Pittsburgh, The Department of Electrical and Computer Engineering (United States); Wei, Fanan [Chinese Academy of Sciences, State Key Laboratory of Robotics, Shenyang Institute of Automation (China); Li, Guangyong, E-mail: gul6@pitt.edu [University of Pittsburgh, The Department of Electrical and Computer Engineering (United States)

    2015-07-15

    Dielectrophoresis (DEP) of rod-shaped nanostructures is attractive because of its exceptional capability to fabricate nanowire-based electronic devices. This efficient manipulation method, however, has a common side effect of assembling a certain number of nanowires at undesired positions. It is therefore essential to understand the underlying physics of DEP of nanowires in order to better guide the assembly. In this work, we propose theoretical methods to characterize the dielectrophoretic force and torque as well as the hydrodynamic drag force and torque on the nanowire (typical length: 10 μm). The trajectory of the nanowire is then simulated based on rigid body dynamics. The nanowire is predicted to either bridge the electrodes or attach on the surface of one electrode. A neighborhood in which the nanowire is more likely to bridge electrodes is found, which is conducive to successful assembly. The simulation study in this work provides us not only a better understanding of the underlying physics but also practical guidance on nanowire assembly by DEP.

  17. Molecular Beam Epitaxy-Grown InGaN Nanomushrooms and Nanowires for White Light Source Applications

    Gasim, Anwar A.; Bhattacharya, Pallab K.; Cha, Dong Kyu; Ng, Tien Khee; Ooi, Boon S.

    2012-01-01

    We report the observation of coexisting InGaN nanomushrooms and nanowires grown via MBE. Photoluminescence characterization shows that the nanostructures emit yellow and blue light, respectively. The combined emission is promising for white-LEDs.

  18. Observation of intact desorption ionization of peptide molecules from arrays of tungsten oxide nanowires by laser irradiation

    Han, Sang Yun [Dept. of Nanochemistry, Gachon University, Seongnam (Korea, Republic of)

    2015-08-15

    Length-controlled WO{sub 3} surface nanowires with a 50 nm diameter were prepared by utilizing anodic Al{sub 2}O{sub 3} templates. Careful control of the fabrication process yielded a set of length-controlled nanowire arrays (Figure 1). The lengths of the nanowires covered a range of 60–250 nm. Typically, a 0.5-μL drop of a sample solution in 10% MeOH that contained 2 pmol of sample was pipetted directly onto the nanowire chips, which were dried under ambient conditions. We report the observation of intact LDI of thermally labile peptides from WO{sub 3} nanowire arrays, which have never been reported for any other metal oxide nanowire arrays. As metal oxides are thermally stable and useful in many applications, and fabrication of various nanostructures are well established, we suggest that the nanostructured surfaces of metal oxides are promising for LDI and thus worthy of further investigations.

  19. Silicon nanowire transistors

    Bindal, Ahmet

    2016-01-01

    This book describes the n and p-channel Silicon Nanowire Transistor (SNT) designs with single and dual-work functions, emphasizing low static and dynamic power consumption. The authors describe a process flow for fabrication and generate SPICE models for building various digital and analog circuits. These include an SRAM, a baseband spread spectrum transmitter, a neuron cell and a Field Programmable Gate Array (FPGA) platform in the digital domain, as well as high bandwidth single-stage and operational amplifiers, RF communication circuits in the analog domain, in order to show this technology’s true potential for the next generation VLSI. Describes Silicon Nanowire (SNW) Transistors, as vertically constructed MOS n and p-channel transistors, with low static and dynamic power consumption and small layout footprint; Targets System-on-Chip (SoC) design, supporting very high transistor count (ULSI), minimal power consumption requiring inexpensive substrates for packaging; Enables fabrication of different types...

  20. Antibacterial activity of single crystalline silver-doped anatase TiO{sub 2} nanowire arrays

    Zhang, Xiangyu, E-mail: zhangxiangyu@tyut.edu.cn; Li, Meng; He, Xiaojing; Hang, Ruiqiang; Huang, Xiaobo; Wang, Yueyue; Yao, Xiaohong; Tang, Bin, E-mail: tangbin@tyut.edu.cn

    2016-05-30

    Graphical abstract: The silver-doped TiO{sub 2} nanowire arrays on titanium foil substrate were synthesized via a two-step process. It includes: deposition of AgTi films on titanium foil by magnetron sputtering; preparation of AgNW arrays on AgTi films via alkali (NaOH) hydrothermal treatment and ion-exchange with HCl, followed by calcinations. - Highlights: • Ag-doped TiO{sub 2} nanowire arrays have been prepared by a duplex-treatment. • The duplex-treatment consisted of magnetron sputtering and hydrothermal growth. • Ag-doped nanowire arrays show excellent antibacterial activity against E. coli. - Abstract: Well-ordered, one-dimensional silver-doped anatase TiO{sub 2} nanowire (AgNW) arrays have been prepared through a hydrothermal growth process on the sputtering-deposited AgTi layers. Electron microscope analyses reveal that the as-synthesized AgNW arrays exhibit a single crystalline phase with highly uniform morphologies, diameters ranging from 85 to 95 nm, and lengths of about 11 μm. Silver is found to be doped into TiO{sub 2} nanowire evenly and mainly exists in the zerovalent state. The AgNW arrays show excellent efficient antibacterial activity against Escherichia coli (E. coli), and all of the bacteria can be killed within 1 h. Additionally, the AgNW arrays can still kill E. coli after immersion for 60 days, suggesting the long-term antibacterial property. The technique reported here is environmental friendly for formation of silver-containing nanostructure without using any toxic organic solvents.

  1. Graphene templated Directional Growth of an Inorganic Nanowire

    2015-03-23

    14,23–25 have only formed randomly oriented or poorly aligned inorganic nanostructures. Here, we show that inorganic nanowires of gold(I) cyanide can... complex . TEM image simulation from the crystal structure The TEM image simulations are performed using MacTempas and CrystalKit. The imaging

  2. Synthesis and superconductivity of In-doped SnTe nanostructures

    Piranavan Kumaravadivel

    2017-07-01

    Full Text Available InxSn1−xTe is a time-reversal invariant candidate 3D topological superconductor derived from doping the topological crystalline insulator SnTe with indium. The ability to synthesize low-dimensional nanostructures of indium-doped SnTe is key for realizing the promise they hold in future spintronic and quantum information processing applications. But hitherto only bulk synthesized crystals and nanoplates have been used to study the superconducting properties. Here for the first time we synthesize InxSn1−xTe nanostructures including nanowires and nanoribbons, which show superconducting transitions. In some of the lower dimensional morphologies, we observe signs of more than one superconducting transition and the absence of complete superconductivity. We propose that material inhomogeneity, such as indium inhomogeneity and possible impurities from the metal catalyst, is amplified in the transport characteristics of the smaller nanostructures and is responsible for this mixed behavior. Our work represents the first demonstration of InxSn1−xTe nanowires with the onset of superconductivity, and points to the need for improving the material quality for future applications.

  3. Magnetic properties of nickel nanostructures grown in AAO membrane

    Oh, S.-L.; Kim, Y.-R.; Malkinski, L.; Vovk, A.; Whittenburg, S.L.; Kim, E.-M.; Jung, J.-S.

    2007-01-01

    One-dimensional nanostructures can be built by performing chemical or electrochemical reactions in the pores of a suitable host or matrix material. We have developed a method of electrodeposition of nickel nanostructures inside cylindrical pores of the anodic aluminum oxide (AAO) membranes, which provides precise control of the nanostructure height. We were able to fabricate hexagonal arrays of particles in the form of spheres, rods and long wires. Magnetization measurements of these nanostructures as function of field and temperature were carried out using a superconducting quantum-interference device magnetometer. The shape of nickel nanostructures has been investigated by field emission scanning electron microscope. The coercivity of the nickel nanostructures measured with the field perpendicular to the membrane was increasing with increasing aspect ratio of the nanostructures. These experimental values of the coercivity, varying from 200 Oe for the spherical nanodots to 730 Oe for the nanowires, are in a fair agreement with our micromagnetic modeling calculations

  4. Magnetic properties of nickel nanostructures grown in AAO membrane

    Oh, S -L [Department of Chemistry, Yonsei University, Seoul (Korea, Republic of); Kim, Y -R [Department of Chemistry, Yonsei University, Seoul (Korea, Republic of); Malkinski, L [Advanced Material Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Vovk, A [Advanced Material Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Whittenburg, S L [Advanced Material Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Kim, E -M [Korea Basic Science Institute, Kangnung 210-702 (Korea, Republic of); Jung, J -S [Department of Chemistry, Kangnung National University, Kangnung 210-702 (Korea, Republic of)

    2007-03-15

    One-dimensional nanostructures can be built by performing chemical or electrochemical reactions in the pores of a suitable host or matrix material. We have developed a method of electrodeposition of nickel nanostructures inside cylindrical pores of the anodic aluminum oxide (AAO) membranes, which provides precise control of the nanostructure height. We were able to fabricate hexagonal arrays of particles in the form of spheres, rods and long wires. Magnetization measurements of these nanostructures as function of field and temperature were carried out using a superconducting quantum-interference device magnetometer. The shape of nickel nanostructures has been investigated by field emission scanning electron microscope. The coercivity of the nickel nanostructures measured with the field perpendicular to the membrane was increasing with increasing aspect ratio of the nanostructures. These experimental values of the coercivity, varying from 200 Oe for the spherical nanodots to 730 Oe for the nanowires, are in a fair agreement with our micromagnetic modeling calculations.

  5. Diamond nanowires: fabrication, structure, properties, and applications.

    Yu, Yuan; Wu, Liangzhuan; Zhi, Jinfang

    2014-12-22

    C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Young's modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    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.

  7. Preparation and characterisation of magnetic nanostructured samples for inelastic neutron scattering experiments

    Kreuzpaintner, Wolfgang

    2010-06-22

    Recent advances in thin-film structuring techniques have generated significant interest in the dynamics of spin waves in magnetic nanostructures and the possible use of inelastic neutron scattering (INS) for their investigation. This thesis describes the design and implementation, at GKSS Research Centre, of equipment for preparation of large and laterally submicron and nanometre structured magnetic samples for such future INS experiments. After a brief resume on spin waves in nanostructures, the development work on new purpose-designed equipment, including high vacuum (HV) argon ion beam milling and ultra high vacuum (UHV) e-beam evaporation setups, is described. Ni nanodot as well as Ni and novel Gd nanowire samples were prepared using combinations of sputter deposition, laser interference lithography, argon ion beam milling, e-beam evaporation and self organisation techniques. With reference to sample preparation, epitaxial growth studies for Ni on Si(100) substrate were performed, resulting in the development of a new deposition process, which by thermal tuning allows for the direct epitaxial growth of Ni on Si with unprecedented crystalline quality. The results of various characterisation experiments on the prepared nanostructured samples, including Scanning Electron Microscopy (SEM), microprobe analysis, Atomic and Magnetic Force Microscopy (AFM/MFM), Vibrating Sample Magnetometry (VSM), X-ray Diffraction (XRD) and Reflectivity (XRR), unpolarised and Polarised Neutron Scattering (PNR) and off-specular scattering by X-rays and neutrons using rocking scans and Time-Of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS), together with various analysis procedures such as Distorted-Wave Born Approximation (DWBA), are reported. The analysis of a Gd nanowire sample by TOF-GISANS led to a novel evaluation technique which in comparison with single wavelength methods allows portions of reciprocal space to be scanned without changing the angle of

  8. Preparation and characterisation of magnetic nanostructured samples for inelastic neutron scattering experiments

    Kreuzpaintner, Wolfgang

    2010-01-01

    Recent advances in thin-film structuring techniques have generated significant interest in the dynamics of spin waves in magnetic nanostructures and the possible use of inelastic neutron scattering (INS) for their investigation. This thesis describes the design and implementation, at GKSS Research Centre, of equipment for preparation of large and laterally submicron and nanometre structured magnetic samples for such future INS experiments. After a brief resume on spin waves in nanostructures, the development work on new purpose-designed equipment, including high vacuum (HV) argon ion beam milling and ultra high vacuum (UHV) e-beam evaporation setups, is described. Ni nanodot as well as Ni and novel Gd nanowire samples were prepared using combinations of sputter deposition, laser interference lithography, argon ion beam milling, e-beam evaporation and self organisation techniques. With reference to sample preparation, epitaxial growth studies for Ni on Si(100) substrate were performed, resulting in the development of a new deposition process, which by thermal tuning allows for the direct epitaxial growth of Ni on Si with unprecedented crystalline quality. The results of various characterisation experiments on the prepared nanostructured samples, including Scanning Electron Microscopy (SEM), microprobe analysis, Atomic and Magnetic Force Microscopy (AFM/MFM), Vibrating Sample Magnetometry (VSM), X-ray Diffraction (XRD) and Reflectivity (XRR), unpolarised and Polarised Neutron Scattering (PNR) and off-specular scattering by X-rays and neutrons using rocking scans and Time-Of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS), together with various analysis procedures such as Distorted-Wave Born Approximation (DWBA), are reported. The analysis of a Gd nanowire sample by TOF-GISANS led to a novel evaluation technique which in comparison with single wavelength methods allows portions of reciprocal space to be scanned without changing the angle of

  9. Visual Understanding of Light Absorption and Waveguiding in Standing Nanowires with 3D Fluorescence Confocal Microscopy.

    Frederiksen, Rune; Tutuncuoglu, Gozde; Matteini, Federico; Martinez, Karen L; Fontcuberta I Morral, Anna; Alarcon-Llado, Esther

    2017-09-20

    Semiconductor nanowires are promising building blocks for next-generation photonics. Indirect proofs of large absorption cross sections have been reported in nanostructures with subwavelength diameters, an effect that is even more prominent in vertically standing nanowires. In this work we provide a three-dimensional map of the light around vertical GaAs nanowires standing on a substrate by using fluorescence confocal microscopy, where the strong long-range disruption of the light path along the nanowire is illustrated. We find that the actual long-distance perturbation is much larger in size than calculated extinction cross sections. While the size of the perturbation remains similar, the intensity of the interaction changes dramatically over the visible spectrum. Numerical simulations allow us to distinguish the effects of scattering and absorption in the nanowire leading to these phenomena. This work provides a visual understanding of light absorption in semiconductor nanowire structures, which is of high interest for solar energy conversion applications.

  10. Wearable, wireless gas sensors using highly stretchable and transparent structures of nanowires and graphene

    Park, Jihun; Kim, Joohee; Kim, Kukjoo; Kim, So-Yun; Cheong, Woon Hyung; Park, Kyeongmin; Song, Joo Hyeb; Namgoong, Gyeongho; Kim, Jae Joon; Heo, Jaeyeong; Bien, Franklin; Park, Jang-Ung

    2016-05-01

    Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area.Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01468b

  11. Synthesis and nanoscale thermal encoding of phase-change nanowires

    Sun Xuhui; Yu Bin; Meyyappan, M.

    2007-01-01

    Low-dimensional phase-change nanostructures provide a valuable research platform for understanding the phase-transition behavior and thermal properties at nanoscale and their potential in achieving superdense data storage. Ge 2 Sb 2 Te 5 nanowires have been grown using a vapor-liquid-solid technique and shown to exhibit distinctive properties that may overcome the present data storage scaling barrier. Local heating of an individual nanowire with a focused electron beam was used to shape a nano-bar-code on a Ge 2 Sb 2 Te 5 nanowire. The data encoding on Ge 2 Sb 2 Te 5 nanowire may promote novel device concepts to implement ultrahigh density, low energy, high speed data storage using phase-change nanomaterials with diverse thermal-programing strategies

  12. Functionalization of lanthanum hydroxide nanowires by atom transfer radical polymerization

    Zhou Mi; Yuan Jinying; Yuan Weizhong; Yin Yingwu; Hong Xiaoyin

    2007-01-01

    Atom transfer radical polymerization (ATRP) has been used to prepare a core-shell hybrid nanostructure successfully: a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of polystyrene (PS) brushes. Transmission electron microscopy (TEM) images indicated that the resulting products presented special structures and different thicknesses of polymer layers. The chemical components and grafted PS quantities of the samples were measured by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The polymers showed narrow polydispersity, which proved that the lanthanum hydroxide nanowires initiated the 'living'/controlled polymerization of styrene. With the modifiability of lanthanum hydroxide nanowires, the solubility increased, which affords a new way to functionalize nanowires

  13. A detailed study of magnetization reversal in individual Ni nanowires

    Vidal, Enrique Vilanova; Ivanov, Yurii P.; Mohammed, Hanan; Kosel, Jü rgen

    2015-01-01

    Magnetic nanowires have emerged as essential components for a broad range of applications. In many cases, a key property of these components is the switching field, which is studied as a function of the angle between the field and the nanowire. We found remarkable differences of up to 100% between the switching fields of different nanowires from the same fabrication batch. Our experimental results and micromagnetic simulations indicate that the nanowires exhibit a single domain behavior and that the switching mechanism includes vortex domain wall motion across the nanowire. The differences between the switching fields are attributed to different cross-sections of the nanowires, as found by electron microscopy. While a circular cross-section yields the smallest switching field values, any deviation from this shape results in an increase of the switching field. The shape of the nanowires' cross-sections is thus a critical parameter that has not been previously taken into account.

  14. A detailed study of magnetization reversal in individual Ni nanowires

    Vidal, Enrique Vilanova

    2015-01-19

    Magnetic nanowires have emerged as essential components for a broad range of applications. In many cases, a key property of these components is the switching field, which is studied as a function of the angle between the field and the nanowire. We found remarkable differences of up to 100% between the switching fields of different nanowires from the same fabrication batch. Our experimental results and micromagnetic simulations indicate that the nanowires exhibit a single domain behavior and that the switching mechanism includes vortex domain wall motion across the nanowire. The differences between the switching fields are attributed to different cross-sections of the nanowires, as found by electron microscopy. While a circular cross-section yields the smallest switching field values, any deviation from this shape results in an increase of the switching field. The shape of the nanowires\\' cross-sections is thus a critical parameter that has not been previously taken into account.

  15. Semi-automated quantification of living cells with internalized nanostructures

    Margineanu, Michael B.

    2016-01-15

    Background Nanostructures fabricated by different methods have become increasingly important for various applications in biology and medicine, such as agents for medical imaging or cancer therapy. In order to understand their interaction with living cells and their internalization kinetics, several attempts have been made in tagging them. Although methods have been developed to measure the number of nanostructures internalized by the cells, there are only few approaches aimed to measure the number of cells that internalize the nanostructures, and they are usually limited to fixed-cell studies. Flow cytometry can be used for live-cell assays on large populations of cells, however it is a single time point measurement, and does not include any information about cell morphology. To date many of the observations made on internalization events are limited to few time points and cells. Results In this study, we present a method for quantifying cells with internalized magnetic nanowires (NWs). A machine learning-based computational framework, CellCognition, is adapted and used to classify cells with internalized and no internalized NWs, labeled with the fluorogenic pH-dependent dye pHrodo™ Red, and subsequently to determine the percentage of cells with internalized NWs at different time points. In a “proof-of-concept”, we performed a study on human colon carcinoma HCT 116 cells and human epithelial cervical cancer HeLa cells interacting with iron (Fe) and nickel (Ni) NWs. Conclusions This study reports a novel method for the quantification of cells that internalize a specific type of nanostructures. This approach is suitable for high-throughput and real-time data analysis and has the potential to be used to study the interaction of different types of nanostructures in live-cell assays.

  16. Contacting nanowires and nanotubes with atomic precision for electronic transport

    Qin, Shengyong; Hellstrom, Sondra; Bao, Zhenan; Boyanov, Boyan; Li, An-Ping

    2012-01-01

    Making contacts to nanostructures with atomic precision is an important process in the bottom-up fabrication and characterization of electronic nanodevices. Existing contacting techniques use top-down lithography and chemical etching, but lack atomic precision and introduce the possibility of contamination. Here, we report that a field-induced emission process can be used to make local contacts onto individual nanowires and nanotubes with atomic spatial precision. The gold nano-islands are deposited onto nanostructures precisely by using a scanning tunneling microscope tip, which provides a clean and controllable method to ensure both electrically conductive and mechanically reliable contacts. To demonstrate the wide applicability of the technique, nano-contacts are fabricated on silicide atomic wires, carbon nanotubes, and copper nanowires. The electrical transport measurements are performed in situ by utilizing the nanocontacts to bridge the nanostructures to the transport probes. © 2012 American Institute of Physics.

  17. Construction of 3D Metallic Nanowire Arrays on Arbitrarily-Shaped Substrate.

    Chen, Fei; Li, Jingning; Yu, Fangfang; Peng, Ru-Wen; Wang, Mu; Mu Wang Team

    Formation of three-dimensional (3D) nanostructures is an important step of advanced manufacture for new concept devices with novel functionality. Despite of great achievements in fabricating nanostructures with state of the art lithography approaches, these nanostructures are normally limited on flat substrates. Up to now it remains challenging to build metallic nanostructures directly on a rough and bumpy surface. Here we demonstrate a unique approach to fabricate metallic nanowire arrays on an arbitrarily-shaped surface by electrodeposition, which is unknown before 2016. Counterintuitively here the growth direction of the nanowires is perpendicular to their longitudinal axis, and the specific geometry of nanowires can be achieved by introducing specially designed shaped substrate. The spatial separation and the width of the nanowires can be tuned by voltage, electrolyte concentration and temperature in electrodeposition. By taking cobalt nanowire array as an example, we demonstrate that head-to-head and tail-to-tail magnetic domain walls can be easily introduced and modulated in the nanowire arrays, which is enlightening to construct new devices such as domain wall racetrack memory. We acknowledge the foundation from MOST and NSF(China).

  18. Magnetic and superconducting nanowires

    Piraux, L.; Encinas, A.; Vila, L.

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  19. Epitaxial growth of hybrid nanostructures

    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.

  20. Metal-dielectric-CNT nanowires for surface-enhanced Raman spectroscopy

    Bond, Tiziana C.; Altun, Ali; Park, Hyung Gyu

    2017-10-03

    A sensor with a substrate includes nanowires extending vertically from the substrate, a hafnia coating on the nanowires that provides hafnia coated nanowires, and a noble metal coating on the hafnia coated nanowires. The top of the hafnia and noble metal coated nanowires bent onto one another to create a canopy forest structure. There are numerous randomly arranged holes that let through scattered light. The many points of contact, hot spots, amplify signals. The methods include the steps of providing a Raman spectroscopy substrate, introducing nano crystals to the Raman spectroscopy substrate, growing a forest of nanowires from the nano crystals on the Raman spectroscopy substrate, coating the nanowires with hafnia providing hafnia coated nanowires, and coating the hafnia coated nanowires with a noble metal or other metal.

  1. Synthesis and integration of one-dimensional nanostructures for chemical gas sensing applications

    Parthangal, Prahalad Madhavan

    The need for improved measurement technology for the detection and monitoring of gases has increased tremendously for maintenance of domestic and industrial health and safety, environmental surveys, national security, food-processing, medical diagnostics and various other industrial applications. Among the several varieties of gas sensors available in the market, solid-state sensors are the most popular owing to their excellent sensitivity, ruggedness, versatility and low cost. Semiconducting metal oxides such as tin oxide (SnO2), zinc oxide (ZnO), and tungsten oxide (WO3) are routinely employed as active materials in these sensors. Since their performance is directly linked to the exposed surface area of the sensing material, one-dimensional nanostructures possessing very high surface to volume ratios are attractive candidates for designing the next generation of sensors. Such nano-sensors also enable miniaturization thereby reducing power consumption. The key to achieve success in one-dimensional nanotechnologies lies in assembly. While synthesis techniques and capabilities continue to expand rapidly, progress in controlled assembly has been sluggish due to numerous technical challenges. In this doctoral thesis work, synthesis and characterization of various one-dimensional nanostructures including nanotubes of SnO2, and nanowires of WO3 and ZnO, as well as their direct integration into miniature sensor platforms called microhotplates have been demonstrated. The key highlights of this research include devising elegant strategies for growing metal oxide nanotubes using carbon nanotubes as templates, substantially reducing process temperatures to enable growth of WO3 nanowires on microhotplates, and successfully fabricating a ZnO nanowire array based sensor using a hybrid nanowire-nanoparticle assembly approach. In every process, the gas-sensing properties of one-dimensional nanostructures were observed to be far superior in comparison with thin films of the same

  2. A general soft-enveloping strategy in the templating synthesis of mesoporous metal nanostructures.

    Fang, Jixiang; Zhang, Lingling; Li, Jiang; Lu, Lu; Ma, Chuansheng; Cheng, Shaodong; Li, Zhiyuan; Xiong, Qihua; You, Hongjun

    2018-02-06

    Metal species have a relatively high mobility inside mesoporous silica; thus, it is difficult to introduce the metal precursors into silica mesopores and suppress the migration of metal species during a reduction process. Therefore, until now, the controlled growth of metal nanocrystals in a confined space, i.e., mesoporous channels, has been very challenging. Here, by using a soft-enveloping reaction at the interfaces of the solid, liquid, and solution phases, we successfully control the growth of metallic nanocrystals inside a mesoporous silica template. Diverse monodispersed nanostructures with well-defined sizes and shapes, including Ag nanowires, 3D mesoporous Au, AuAg alloys, Pt networks, and Au nanoparticle superlattices are successfully obtained. The 3D mesoporous AuAg networks exhibit enhanced catalytic activities in an electrochemical methanol oxidation reaction. The current soft-enveloping synthetic strategy offers a robust approach to synthesize diverse mesoporous metal nanostructures that can be utilized in catalysis, optics, and biomedicine applications.

  3. Synthesis and magnetic properties of bundled and dispersed Co3O4 nanowires

    Zhang, B.B.; Wang, P.F.; Xu, J.C.; Han, Y.B.; Jin, H.X.; Jin, D.F.; Peng, X.L.; Hong, B.; Li, J.; Yang, Y.T.; Gong, J.; Ge, H.L.; Wang, X.Q.

    2016-01-01

    Highlights: • Co 3 O 4 nanowires possessed the same diameter and the different interwires distance. • All samples possessed antiferromagnetism and superparamagnetism at high temperature. • The exchange bias effect was observed at low temperature. • The surface spin coupling restrained the surface effect of magnetic nanostructures. - Abstract: The magnetic Co 3 O 4 nanowires were synthesized using the templates of SBA-15, and then the well-dispersed nanowires (D-wires) were separated from the bundled ordered nanowires (B-wires) with the centrifugal technique. TEM images indicated that D-wires were highly dispersed Co 3 O 4 nanowires and B-wires existed in bundles. All samples possessed the antiferromagnetism and superparamagnetism at high temperature. After revealing the intrinsic magnetic properties of Co 3 O 4 nanowires with D-wires, the magnetic behavior of B-wires was discussed in detail, and then the magnetic interaction between neighboring nanowires could be deduced. The exchange bias effect from the body Co 3 O 4 antiferromagnetism and surface ferromagnetism was observed at low temperature. The magnetization of B-wires was higher than that of D-wires, which was attributed to the constraint of the surface spin coupling between the neighboring nanowires to the surface affect of nanostructures.

  4. Self-assembled nanostructures

    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.

  5. Optical Binding of Nanowires

    Simpson, Stephen Hugh; Zemánek, Pavel; Marago, O.M.; Jones, P.H.; Hanna, S.

    2017-01-01

    Roč. 17, č. 6 (2017), s. 3485-3492 ISSN 1530-6984 R&D Projects: GA ČR GB14-36681G Grant - others:AV ČR(CZ) CNR-16-12 Program:Bilaterální spolupráce Institutional support: RVO:68081731 Keywords : optical binding nanowires * Brownian motion * self-organization * non-equilibrium thermodynamics * non-equilibrium steady state * spin-orbit coupling * emergent phenomena Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 12.712, year: 2016

  6. Fabrication of multilayer nanowires

    Kaur, Jasveer, E-mail: kaurjasveer89@gmail.com; Singh, Avtar; Kumar, Davinder [Department of Physics, Punjabi University Patiala, 147002, Punjab (India); Thakur, Anup; Kaur, Raminder, E-mail: raminder-k-saini@yahoo.com [Department of Basic and Applied Sciences, Punjabi University Patiala, 147002, Punjab (India)

    2016-05-06

    Multilayer nanowires were fabricated by potentiostate ectrodeposition template synthesis method into the pores of polycarbonate membrane. In present work layer by layer deposition of two different metals Ni and Cu in polycarbonate membrane having pore size of 600 nm were carried out. It is found that the growth of nanowires is not constant, it varies with deposition time. Scanning electron microscopy (SEM) is used to study the morphology of fabricated multilayer nanowires. An energy dispersive X-ray spectroscopy (EDS) results confirm the composition of multilayer nanowires. The result shows that multilayer nanowires formed is dense.

  7. Fabrication of multilayer nanowires

    Kaur, Jasveer; Singh, Avtar; Kumar, Davinder; Thakur, Anup; Kaur, Raminder

    2016-01-01

    Multilayer nanowires were fabricated by potentiostate ectrodeposition template synthesis method into the pores of polycarbonate membrane. In present work layer by layer deposition of two different metals Ni and Cu in polycarbonate membrane having pore size of 600 nm were carried out. It is found that the growth of nanowires is not constant, it varies with deposition time. Scanning electron microscopy (SEM) is used to study the morphology of fabricated multilayer nanowires. An energy dispersive X-ray spectroscopy (EDS) results confirm the composition of multilayer nanowires. The result shows that multilayer nanowires formed is dense.

  8. Room temperature synthesis and characterization of ultralong Cd(OH)2 nanowires: a simple and template-free chemical route

    Sahraei, R.; Daneshfar, A.; Roushani, M.; Mihandoost, A.; Nabiyouni, G.; Majles Ara, M.H.

    2012-01-01

    Ultralong Cd(OH) 2 nanowires were fabricated in high yield by a convenient chemical method using alkali medium at room temperature without using any templates. The preparation conditions induce a unilateral growth of nanowires, despite the absence of any template. The length of the nanowires reached several hundreds of micrometers, giving an aspect ratio of a few thousands. The X-ray diffraction shows that the Cd(OH) 2 nanostructures crystallized in the wurtzite structure without any special orientation. The photoluminescence spectrum of Cd(OH) 2 nanostructures appears as two emission bands: one related to green emission at 475-510 nm, and the other related to deep level emission at 510-540 nm. Also the formation mechanisms of the nanowires are presented. The growth mechanism involves the irreversible and specifically oriented self-assembly of primary nanocrystals and results in the formation of the nanowires. (orig.)

  9. Conducting polymer nanowire arrays for high performance supercapacitors.

    Wang, Kai; Wu, Haiping; Meng, Yuena; Wei, Zhixiang

    2014-01-15

    This Review provides a brief summary of the most recent research developments in the fabrication and application of one-dimensional ordered conducting polymers nanostructure (especially nanowire arrays) and their composites as electrodes for supercapacitors. By controlling the nucleation and growth process of polymerization, aligned conducting polymer nanowire arrays and their composites with nano-carbon materials can be prepared by employing in situ chemical polymerization or electrochemical polymerization without a template. This kind of nanostructure (such as polypyrrole and polyaniline nanowire arrays) possesses high capacitance, superior rate capability ascribed to large electrochemical surface, and an optimal ion diffusion path in the ordered nanowire structure, which is proved to be an ideal electrode material for high performance supercapacitors. Furthermore, flexible, micro-scale, threadlike, and multifunctional supercapacitors are introduced based on conducting polyaniline nanowire arrays and their composites. These prototypes of supercapacitors utilize the high flexibility, good processability, and large capacitance of conducting polymers, which efficiently extend the usage of supercapacitors in various situations, and even for a complicated integration system of different electronic devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Strain analysis of nanowire interfaces in multiscale composites

    Malakooti, Mohammad H.; Zhou, Zhi; Spears, John H.; Shankwitz, Timothy J.; Sodano, Henry A.

    2016-04-01

    Recently, the reinforcement-matrix interface of fiber reinforced polymers has been modified through grafting nanostructures - particularly carbon nanotubes and ZnO nanowires - on to the fiber surface. This type of interface engineering has made a great impact on the development of multiscale composites that have high stiffness, interfacial strength, toughness, and vibrational damping - qualities that are mutually exclusive to a degree in most raw materials. Although the efficacy of such nanostructured interfaces has been established, the reinforcement mechanisms of these multiscale composites have not been explored. Here, strain transfer across a nanowire interphase is studied in order to gain a heightened understanding of the working principles of physical interface modification and the formation of a functional gradient. This problem is studied using a functionally graded piezoelectric interface composed of vertically aligned lead zirconate titanate nanowires, as their piezoelectric properties can be utilized to precisely control the strain on one side of the interface. The displacement and strain across the nanowire interface is captured using digital image correlation. It is demonstrated that the material gradient created through nanowires cause a smooth strain transfer from reinforcement phase into matrix phase that eliminates the stress concentration between these phases, which have highly mismatched elasticity.

  11. 2009 Clusters, Nanocrystals & Nanostructures GRC

    Wang, Lai-Sheng [Washington State Univ., Pullman, WA (United States)

    2009-07-19

    For over thirty years, this Gordon Conference has been the premiere meeting for the field of cluster science, which studies the phenomena that arise when matter becomes small. During its history, participants have witnessed the discovery and development of many novel materials, including C60, carbon nanotubes, semiconductor and metal nanocrystals, and nanowires. In addition to addressing fundamental scientific questions related to these materials, the meeting has always included a discussion of their potential applications. Consequently, this conference has played a critical role in the birth and growth of nanoscience and engineering. The goal of the 2009 Gordon Conference is to continue the forward-looking tradition of this meeting and discuss the most recent advances in the field of clusters, nanocrystals, and nanostructures. As in past meetings, this will include new topics that broaden the field. In particular, a special emphasis will be placed on nanomaterials related to the efficient use, generation, or conversion of energy. For example, we anticipate presentations related to batteries, catalysts, photovoltaics, and thermoelectrics. In addition, we expect to address the controversy surrounding carrier multiplication with a session in which recent results addressing this phenomenon will be discussed and debated. The atmosphere of the conference, which emphasizes the presentation of unpublished results and lengthy discussion periods, ensures that attendees will enjoy a valuable and stimulating experience. Because only a limited number of participants are allowed to attend this conference, and oversubscription is anticipated, we encourage all interested researchers from academia, industry, and government institutions to apply as early as possible. An invitation is not required. We also encourage all attendees to submit their latest results for presentation at the poster sessions. We anticipate that several posters will be selected for 'hot topic' oral

  12. Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

    Maijenburg, A.W.; Rodijk, E.J.B.; Maas, M.G.; ten Elshof, Johan E.

    2014-01-01

    Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these

  13. Nanowire Growth for Photovoltaics

    Holm, Jeppe Vilstrup

    Solar cells commercial success is based on an efficiency/cost calculation. Nanowire solar cells is one of the foremost candidates to implement third generation photo voltaics, which are both very efficient and cheap to produce. This thesis is about our progress towards commercial nanowire solar...... cells. Resonance effects between the light and nanowire causes an inherent concentration of the sunlight into the nanowires, and means that a sparse array of nanowires (less than 5% of the area) can absorb all the incoming light. The resonance effects, as well as a graded index of refraction, also traps...... the light. The concentration and light trapping means that single junction nanowire solar cells have a higher theoretical maximum efficiency than equivalent planar solar cells. We have demonstrated the built-in light concentration of nanowires, by growing, contacting and characterizing a solar cell...

  14. Multisensor system based on bisphthalocyanine nanowires for the detection of antioxidants

    Gay Martín, Mónica; Saja, José Antonio de; Muñoz, Raquel; Rodríguez-Méndez, María Luz

    2012-01-01

    Highlights: ► Sensors based on LnPc 2 nanowires can be prepared by electrodeposition (EDP). ► An electronic tongue can be constructed by combining EDP sensors with a data treatment system. ► The e-tongue is able to discriminate antioxidants of interest in the food industry. ► The fast preparation and excellent performance of these nanostructured sensors is an advantage. - Abstract: Electrophoretic deposition has been used to prepare thin films based on nanowires of three lanthanoid bisphthalocyaninates (including dysprosium, gadolinium and lutetium). Nanowires of similar structural characteristics have been obtained for the three compounds by tuning the electrophoretic conditions according to the redox properties of each phthalocyanine. The three electrodes have been used to form an array of sensors that has been employed to discriminate phenolic antioxidants of interest in the food industry including caffeic, gallic, vanillic and ferulic acids. The Principal Component Analysis (PCA) and the Partial Least Squares Discriminant Analysis (PLS-DA) of the electrochemical signals has allowed a clear discrimination of the four phenols analyzed according to the number of phenolic groups attached to the structure (monophenol, diphenol or triphenol). The PCA loading plots indicate that the three electrodes bring complementary information facilitating the discrimination of the studied solutions. In addition, good correlations between the intensity of the redox processes observed in the electrodes and the concentration of phenolic compounds have been found with detection limits in the range of 10 −5 –10 −6 mol L −1 and good reproducibility. The fast preparation of these nanowires based films and their excellent performance offer a new sensing platform for the detection of antioxidants in a fast, reliable way.

  15. Formation of tungsten oxide nanowires by ion irradiation and vacuum annealing

    Zheng, Xu-Dong; Ren, Feng; Wu, Heng-Yi; Qin, Wen-Jing; Jiang, Chang-Zhong

    2018-04-01

    Here we reported the fabrication of tungsten oxide (WO3-x ) nanowires by Ar+ ion irradiation of WO3 thin films followed by annealing in vacuum. The nanowire length increases with increasing irradiation fluence and with decreasing ion energy. We propose that the stress-driven diffusion of the irradiation-induced W interstitial atoms is responsible for the formation of the nanowires. Comparing to the pristine film, the fabricated nanowire film shows a 106-fold enhancement in electrical conductivity, resulting from the high-density irradiation-induced vacancies on the oxygen sublattice. The nanostructure exhibits largely enhanced surface-enhanced Raman scattering effect due to the oxygen vacancy. Thus, ion irradiation provides a powerful approach for fabricating and tailoring the surface nanostructures of semiconductors.

  16. A Facile Fabrication of Silver-Coated Copper Nanowires by Galvanic Replacement

    Xin He

    2016-01-01

    Full Text Available We demonstrated a general strategy to fabricate silver-coated copper nanowires by a galvanic replacement, which is guided by the chemical principle that metal ions (silver ions with a relatively high reduction potential can galvanically etch nanostructure made from a less metal (copper. Well-dispersed and high-yielded copper nanowires were initially synthesized and then introduced into silver-ammonia solution for the growth of silver nanocrystals on the nanowire surfaces under vigorous oscillation. The results of X-ray diffraction, scanning electron microscope, and transmission electron microscope revealed that the silver nanocrystals were uniformly distributed on the copper nanowire surfaces to form Cu-Ag heterostructures. The concentration of silver-ammonia solution and the time of replacement reaction determine the size and density of the silver nanocrystals. Our investigation might pave the way to the synthesis of other bimetallic nanostructures via a facile, fast, and economical route.

  17. Two simple examples for the micro-nano integration of nanowires as electronic device elements

    Adelung, Rainer

    2011-01-01

    As a part of the conference talk about the mass fabrication and applications of nanostructures, the aim of this paper is to review and compare two approaches for the simple fabrication and integration and of nanostructures into Si-based microchips. The purpose of the integration is the utilization of the different and advanced electronic properties of nanowires. The first method is based on a fracture approach, that integrates nanowires bound to a Si substrate between micro electrodes. These are arrange in a horizontal manner, the second approach allows to integrate free standing nanowires and even 3 dimensional nanowire networks in the chip. As an example for the electronic properties of the nano-micro integrated structures the UV light sensitivity is sown here.

  18. Semiconductor Nanowires and Nanotubes for Energy Conversion

    Fardy, Melissa Anne

    In recent years semiconductor nanowires and nanotubes have garnered increased attention for their unique properties. With their nanoscale dimensions comes high surface area and quantum confinement, promising enhancements in a wide range of applications. 1-dimensional nanostructures are especially attractive for energy conversion applications where photons, phonons, and electrons come into play. Since the bohr exciton radius and phonon and electron mean free paths are on the same length scales as nanowire diameters, optical, thermal, and electrical properties can be tuned by simple nanowire size adjustments. In addition, the high surface area inherent to nanowires and nanotubes lends them towards efficient charge separation and superior catalytic performance. In thermoelectric power generation, the nanoscale wire diameter can effectively scatter phonons, promoting reductions in thermal conductivity and enhancements in the thermoelectric figure of merit. To that end, single-crystalline arrays of PbS, PbSe, and PbTe nanowires have been synthesized by a chemical vapor transport approach. The electrical and thermal transport properties of the nanowires were characterized to investigate their potential as thermoelectric materials. Compared to bulk, the lead chalcogenide nanowires exhibit reduced thermal conductivity below 100 K by up to 3 orders of magnitude, suggesting that they may be promising thermoelectric materials. Smaller diameters and increased surface roughness are expected to give additional enhancements. The solution-phase synthesis of PbSe nanowires via oriented attachment of nanoparticles enables facile surface engineering and diameter control. Branched PbSe nanowires synthesized by this approach showed near degenerately doped charge carrier concentrations. Compared to the bulk, the PbSe nanowires exhibited a similar Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K. Thermal annealing of the Pb

  19. Surface state modulation through wet chemical treatment as a route to controlling the electrical properties of ZnO nanowire arrays investigated with XPS

    Lord, Alex M.; Maffeis, Thierry G.; Allen, Martin W.; Morgan, David; Davies, Philip R.; Jones, Daniel R.; Evans, Jonathan E.; Smith, Nathan A.; Wilks, Steve P.

    2014-01-01

    Highlights: • Direct measurement of the surface band bending exhibited by ZnO nanowires using monochromatic XPS. • Modulation of the surface depletion region using wet chemical treatment (EtOH, H 2 O 2 ). • The measured surface potential barrier agrees with electrical measurements of individual nanowires. • H 2 O 2 depletes the nanowire of charge carriers while EtOH donates electrons at the surface. • EtOH has the effect of restoring the surface potential barrier of oxidised nanowires. - Abstract: ZnO is a wide bandgap semiconductor that has many potential applications including solar cell electrodes, transparent thin film transistors and gas/biological sensors. Since the surfaces of ZnO materials have no amorphous or oxidised layers, they are very environmentally sensitive, making control of their semiconductor properties challenging. In particular, the electronic properties of ZnO nanostructures are dominated by surface effects while surface conduction layers have been observed in thin films and bulk crystals. Therefore, the ability to use the ZnO materials in a controlled way depends on the development of simple techniques to modulate their surface electronic properties. Here, we use monochromatic x-ray photoelectron spectroscopy (XPS) to investigate the use of different wet chemical treatments (EtOH, H 2 O 2 ) to control the electronic properties of ZnO nanowires by modulating the surface depletion region. The valence band and core level XPS spectra are used to explore the relationship between the surface chemistry of the nanowires and the surface band bending

  20. Wettability control by DLC coated nanowire topography

    Li, Zihui; Meng, Fanhao; Liu, Xuanyong

    2011-04-01

    Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50°-141°. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable ID/IG and sp2/sp3 ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF4 implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF4 implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF4 implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity.

  1. Synthesis and characterization of MnO2 nanowires

    Ghorbani, Mohammad Hossein; Davarpanah, Abdol Mahmood

    2017-01-01

    Manganese oxides are of more interest to researchers because of their ability as catalysts and lithium batteries. In this research, MnO2 nanowires with diameter about 45 nm were synthesized by sol-gel method at room temperature (RT). Effect of increasing the annealing temperature from 400∘C to 600∘C on crystalline structure of nanostructure were studied and average crystallite size was estimated about 22 nm. X-ray Diffraction (XRD) method, Energy-Dispersive X-ray Diffraction (EDXD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) were used to characterize the nanowires of MnO2.

  2. Tunneling and Transport in Nanowires

    Goldman, Allen M.

    2016-01-01

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO_3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  3. Tunneling and Transport in Nanowires

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  4. Morphology-dependent activity of Pt nanocatalysts for ethanol oxidation in acidic media: Nanowires versus nanoparticles

    Zhou Weiping; Li Meng; Koenigsmann, Christopher; Ma Chao; Wong, Stanislaus S.; Adzic, Radoslav R.

    2011-01-01

    Highlights: → We demonstrate the morphology effect of Pt catalysts in electrooxidation of ethanol and CO in an acidic solution. → Pt nanowires and nanoparticles were used as catalysts. → Pt nanowires display a higher catalytic activity by a factor of at least two relative to those nanoparticles for ethanol oxidation. → The rate for CO monolayer oxidation exhibits similar morphology-dependent behavior with a markedly enhanced rate on the Pt nanowires. - Abstract: The morphology of nanostructured Pt catalysts is known to affect significantly the kinetics of various reactions. Herein, we report on a pronounced morphology effect in the electrooxidation of ethanol and carbon monoxide (CO) on Pt nanowires and nanoparticles in an acidic solution. The high resolution transmission electron microscopy analysis showed the inherent morphology difference between these two nanostructured catalysts. Voltammetric and chronoamperometric studies of the ethanol electrooxidation revealed that these nanowires had a higher catalytic activity by a factor of two relative to these nanoparticles. The rate for CO monolayer oxidation exhibits similar morphology-dependent behavior with a markedly enhanced rate on the Pt nanowires. In situ infrared reflection-absorption spectroscopy measurements revealed a different trend for chemisorbed CO formation and CO 2 -to-acetic acid reaction product ratios on these two nanostructures. The morphology-induced change in catalytic activity and selectivity in ethanol electrocatalysis is discussed in detail.

  5. Morphology-dependent activity of Pt nanocatalysts for ethanol oxidation in acidic media: Nanowires versus nanoparticles

    Zhou Weiping, E-mail: wpzhou@bnl.gov [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Li Meng [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Koenigsmann, Christopher [Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794 (United States); Ma Chao [Condensed Matter Physics and Materials Sciences Department, Brookhaven National Laboratory, Building 480, Upton, NY 11973 (United States); Wong, Stanislaus S. [Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794 (United States); Condensed Matter Physics and Materials Sciences Department, Brookhaven National Laboratory, Building 480, Upton, NY 11973 (United States); Adzic, Radoslav R. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2011-11-30

    Highlights: > We demonstrate the morphology effect of Pt catalysts in electrooxidation of ethanol and CO in an acidic solution. > Pt nanowires and nanoparticles were used as catalysts. > Pt nanowires display a higher catalytic activity by a factor of at least two relative to those nanoparticles for ethanol oxidation. > The rate for CO monolayer oxidation exhibits similar morphology-dependent behavior with a markedly enhanced rate on the Pt nanowires. - Abstract: The morphology of nanostructured Pt catalysts is known to affect significantly the kinetics of various reactions. Herein, we report on a pronounced morphology effect in the electrooxidation of ethanol and carbon monoxide (CO) on Pt nanowires and nanoparticles in an acidic solution. The high resolution transmission electron microscopy analysis showed the inherent morphology difference between these two nanostructured catalysts. Voltammetric and chronoamperometric studies of the ethanol electrooxidation revealed that these nanowires had a higher catalytic activity by a factor of two relative to these nanoparticles. The rate for CO monolayer oxidation exhibits similar morphology-dependent behavior with a markedly enhanced rate on the Pt nanowires. In situ infrared reflection-absorption spectroscopy measurements revealed a different trend for chemisorbed CO formation and CO{sub 2}-to-acetic acid reaction product ratios on these two nanostructures. The morphology-induced change in catalytic activity and selectivity in ethanol electrocatalysis is discussed in detail.

  6. Synthesis, characterization and photoluminescence of tin oxide nanoribbons and nanowires

    Duraia, El-Shazly M.A., E-mail: duraia_physics@yahoo.co [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Mansorov, Z.A. [Al-Farabi Kazakh National University, Almaty (Kazakhstan); Tokmolden, S. [Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan)

    2009-11-15

    In this work we report the successful formation of tin oxide nanowires and tin oxide nanoribbons with high yield and by using simple cheap method. We also report the formation of curved nanoribbon, wedge-like tin oxide nanowires and star-like nanowires. The growth mechanism of these structures has been studied. Scanning electron microscope was used in the analysis and the EDX analysis showed that our samples is purely Sn and O with ratio 1:2. X-ray analysis was also used in the characterization of the tin oxide nanowire and showed the high crystallinity of our nanowires. The mechanism of the growth of our1D nanostructures is closely related to the vapor-liquid-solid (VLS) process. The photoluminescence PL measurements for the tin oxide nanowires indicated that there are three stable emission peaks centered at wavelengths 630, 565 and 395 nm. The nature of the transition may be attributed to nanocrystals inside the nanobelts or to Sn or O vacancies occurring during the growth which can induce trapped states in the band gap.

  7. Application of Nanostructures in Electrochromic Materials and Devices: Recent Progress

    Jin Min Wang

    2010-11-01

    Full Text Available The recent progress in application of nanostructures in electrochromic materials and devices is reviewed. ZnO nanowire array modified by viologen and WO3, crystalline WO3 nanoparticles and nanorods, mesoporous WO3 and TiO2, poly(3,4-ethylenedioxythiophene nanotubes, Prussian blue nanoinks and nanostructures in switchable mirrors are reviewed. The electrochromic properties were significantly enhanced by applying nanostructures, resulting in faster switching responses, higher stability and higher optical contrast. A perspective on the development trends in electrochromic materials and devices is also proposed.

  8. Manganese oxide nanowires, films, and membranes and methods of making

    Suib, Steven Lawrence [Storrs, CT; Yuan, Jikang [Storrs, CT

    2008-10-21

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

  9. Magnetic properties of nickel nanowires decorated with cobalt nanoparticles fabricated by two step electrochemical deposition technique

    Maaz, K., E-mail: maaz@impcas.ac.cn [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Nanomaterials Research Group, Physics Division, PINSTECH, Nilore, 45650, Islamabad (Pakistan); Duan, J.L. [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Karim, S. [Nanomaterials Research Group, Physics Division, PINSTECH, Nilore, 45650, Islamabad (Pakistan); Chen, Y.H.; Yao, H.J.; Mo, D.; Sun, Y.M. [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Liu, J., E-mail: j.liu@impcas.ac.cn [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

    2016-10-01

    We demonstrate fabrication and magnetic characterization of novel nanostructures composed of Ni nanowires decorated with Co nanoparticles by two step etching and electrochemical deposition in polycarbonate template. Structural analysis confirmed the formation of nickel nanowires with diameter of 62 nm which are surrounded by cobalt nanoparticles of about 15 nm in diameter. By electron microscopy analyses it is evident that the nanoparticles are distributed on the surface of the nanowires. Analysis of magnetization data indicates that ferromagnetic Ni nanowires exhibit an easy axis of magnetization parallel to the wire long-axis while the angular dependence of coercivity indicates that magnetization reversal occurs through the curling process in these nanowires. An exchange bias accompanied by vertical shift in magnetization was observed below ∼20 K, measured under a cooling field of 1 kOe, which is attributed to the spin interactions between the spin-glass like surface layer and ferromagnetic core of the nanowires and nanoparticles. - Highlights: • Co-decorated Ni nanowires were fabricated by two-step electrodeposition technique. • The nanoparticles are distributed on the surface of nanowires. • Magnetization reversal occurs through the curling process in the nanowires. • Temperature dependent coercivity follows thermal activation model.

  10. Non-chemotoxic induction of cancer cell death using magnetic nanowires

    Contreras, Maria F.

    2015-03-01

    In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 μg/mL) of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz) for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods. © 2015 Contreras et al.

  11. Non-chemotoxic induction of cancer cell death using magnetic nanowires

    Contreras, Maria F.; Sougrat, Rachid; Zaher, Amir Omar; Ravasi, Timothy; Kosel, Jü rgen

    2015-01-01

    In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 μg/mL) of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz) for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods. © 2015 Contreras et al.

  12. Chirality-Discriminated Conductivity of Metal-Amino Acid Biocoordination Polymer Nanowires.

    Zheng, Jianzhong; Wu, Yijin; Deng, Ke; He, Meng; He, Liangcan; Cao, Jing; Zhang, Xugang; Liu, Yaling; Li, Shunxing; Tang, Zhiyong

    2016-09-27

    Biocoordination polymer (BCP) nanowires are successfully constructed through self-assembly of chiral cysteine amino acids and Cd cations in solution. The varied chirality of cysteine is explored to demonstrate the difference of BCP nanowires in both morphology and structure. More interestingly and surprisingly, the electrical property measurement reveals that, although all Cd(II)/cysteine BCP nanowires behave as semiconductors, the conductivity of the Cd(II)/dl-cysteine nanowires is 4 times higher than that of the Cd(II)/l-cysteine or Cd(II)/d-cysteine ones. The origin of such chirality-discriminated characteristics registered in BCP nanowires is further elucidated by theoretical calculation. These findings demonstrate that the morphology, structure, and property of BCP nanostructures could be tuned by the chirality of the bridging ligands, which will shed light on the comprehension of chirality transcription as well as construction of chirality-regulated functional materials.

  13. From nanodiamond to nanowires.

    Barnard, A.; Materials Science Division

    2005-01-01

    Recent advances in the fabrication and characterization of semiconductor and metallic nanowires are proving very successful in meeting the high expectations of nanotechnologists. Although the nanoscience surrounding sp{sup 3} bonded carbon nanotubes has continued to flourish over recent years the successful synthesis of the sp{sup 3} analogue, diamond nanowires, has been limited. This prompts questions as to whether diamond nanowires are fundamentally unstable. By applying knowledge obtained from examining the structural transformations in nanodiamond, a framework for analyzing the structure and stability of diamond nanowires may be established. One possible framework will be discussed here, supported by results of ab initio density functional theory calculations used to study the structural relaxation of nanodiamond and diamond nanowires. The results show that the structural stability and electronic properties of diamond nanowires are dependent on the surface morphology, crystallographic direction of the principal axis, and the degree of surface hydrogenation.

  14. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    Banerjee, Arghya Narayan

    2011-01-01

    Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and

  15. Tree-like SnO2 nanowires and optical properties

    Tao Tao; Chen Qiyuan; Hu Huiping; Chen Ying

    2011-01-01

    Research highlights: → Tree-like SnO 2 nanowires can be grown as low as 1100 deg. C by a vapour-solid process using a milled SnO 2 powder as the evaporation source. → FT-IR and PL measurements have shown that the tree-like nanostructures lead to superb physical properties. → The PL spectrum of such tree-like nanowires exhibits a strong PL peak at 548 nm. - Abstract: Tree-like SnO 2 nanowires have been grown by a vapor-solid process using a milled SnO 2 powder as the evaporation source. Phase, structural evolution and chemical composition were investigated using X-ray diffraction (XRD), X-ray spectrometry (EDS), and scanning electron microscopy (SEM). The process yields a large proportion of ultra-long rutile nanowires of 50-150 nm diameter and lengths up to several tens of micrometers. High-resolution transmission electron microscopy (HRTEM) shows that the SnO 2 nanowires are single crystals in the (1 0 1) growth direction with scattered smaller crystals or nanowires as the tree branches. The SnO 2 nanostructures were also examined using Fourier transform infra-red (FT-IR) and photoluminescence (PL) spectroscopy. A strong emission band centered at 548 nm dominated the PL spectrum of the tree-like nanowires.

  16. Study of quantum confinement effects in ZnO nanostructures

    Movlarooy, Tayebeh

    2018-03-01

    Motivation to fact that zinc oxide nanowires and nanotubes with successful synthesis and the mechanism of formation, stability and electronic properties have been investigated; in this study the structural, electronic properties and quantum confinement effects of zinc oxide nanotubes and nanowires with different diameters are discussed. The calculations within density functional theory and the pseudo potential approximation are done. The electronic structure and energy gap for Armchair and zigzag ZnO nanotubes with a diameter of about 4 to 55 Angstrom and ZnO nanowires with a diameter range of 4 to 23 Å is calculated. The results revealed that due to the quantum confinement effects, by reducing the diameter of nanowires and nanotubes, the energy gap increases. Zinc oxide semiconductor nanostructures since having direct band gap with size-dependent and quantum confinement effect are recommended as an appropriate candidate for making nanoscale optoelectronic devices.

  17. Aluminum-catalyzed silicon nanowires: Growth methods, properties, and applications

    Hainey, Mel F.; Redwing, Joan M. [Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2016-12-15

    Metal-mediated vapor-liquid-solid (VLS) growth is a promising approach for the fabrication of silicon nanowires, although residual metal incorporation into the nanowires during growth can adversely impact electronic properties particularly when metals such as gold and copper are utilized. Aluminum, which acts as a shallow acceptor in silicon, is therefore of significant interest for the growth of p-type silicon nanowires but has presented challenges due to its propensity for oxidation. This paper summarizes the key aspects of aluminum-catalyzed nanowire growth along with wire properties and device results. In the first section, aluminum-catalyzed nanowire growth is discussed with a specific emphasis on methods to mitigate aluminum oxide formation. Next, the influence of growth parameters such as growth temperature, precursor partial pressure, and hydrogen partial pressure on nanowire morphology is discussed, followed by a brief review of the growth of templated and patterned arrays of nanowires. Aluminum incorporation into the nanowires is then discussed in detail, including measurements of the aluminum concentration within wires using atom probe tomography and assessment of electrical properties by four point resistance measurements. Finally, the use of aluminum-catalyzed VLS growth for device fabrication is reviewed including results on single-wire radial p-n junction solar cells and planar solar cells fabricated with nanowire/nanopyramid texturing.

  18. Template Synthesis of Nanostructured Polymeric Membranes by Inkjet Printing.

    Gao, Peng; Hunter, Aaron; Benavides, Sherwood; Summe, Mark J; Gao, Feng; Phillip, William A

    2016-02-10

    The fabrication of functional nanomaterials with complex structures has been serving great scientific and practical interests, but current fabrication and patterning methods are generally costly and laborious. Here, we introduce a versatile, reliable, and rapid method for fabricating nanostructured polymeric materials. The novel method is based on a combination of inkjet printing and template synthesis, and its utility and advantages in the fabrication of polymeric nanomaterials is demonstrated through three examples: the generation of polymeric nanotubes, nanowires, and thin films. Layer-by-layer-assembled nanotubes can be synthesized in a polycarbonate track-etched (PCTE) membrane by printing poly(allylamine hydrochloride) and poly(styrenesulfonate) sequentially. This sequential deposition of polyelectrolyte ink enables control over the surface charge within the nanotubes. By a simple change of the printing conditions, polymeric nanotubes or nanowires were prepared by printing poly(vinyl alcohol) in a PCTE template. In this case, the high-throughput nature of the method enables functional nanomaterials to be generated in under 3 min. Furthermore, we demonstrate that inkjet printing paired with template synthesis can be used to generate patterns comprised of chemically distinct nanomaterials. Thin polymeric films of layer-by-layer-assembled poly(allylamine hydrochloride) and poly(styrenesulfonate) are printed on a PCTE membrane. Track-etched membranes covered with the deposited thin films reject ions and can potentially be utilized as nanofiltration membranes. When the fabrication of these different classes of nanostructured materials is demonstrated, the advantages of pairing template synthesis with inkjet printing, which include fast and reliable deposition, judicious use of the deposited materials, and the ability to design chemically patterned surfaces, are highlighted.

  19. On quantum efficiency of photoluminescence in ZnO layers and nanostructures

    Reshchikov, M.A., E-mail: mreshchi@vcu.ed [Physics Department, Virginia Commonwealth University, 701 W. Grace St., Richmond, VA 23284 (United States); El-Shaer, A.; Behrends, A.; Bakin, A.; Waag, A. [Institute of Semiconductor Technology, Technical University of Braunschweig, Braunschweig D-38106 (Germany)

    2009-12-15

    In this work we studied PL in ZnO layers and nanostructures, including ZnO homoepitaxial layers on ZnO substrate and ZnO-Zn{sub 1-x}Mg{sub x}O single quantum well (SQW) structures grown on sapphire substrates by MBE, and ZnO nanowires grown on sapphire by MOCVD. The external quantum efficiency (QE) of PL in O-face ZnO layers exceeded that in Zn-face ZnO layers by two orders of magnitude at low temperatures. In a sample with SQW the combined external QE from the 4.6-nm-wide SQW and 50-nm-thick Zn{sub 1-x}Mg{sub x}O barriers achieved 28% at 15 K. The highest external QE was observed in one of the samples with ZnO nanowires-52% at 15 K and 2% at 300 K. Contribution of defect-related PL bands in ZnO nanowires samples was extremely low.

  20. Silicon nanowire structures as high-sensitive pH-sensors

    Belostotskaya, S O; Chuyko, O V; Kuznetsov, A E; Kuznetsov, E V; Rybachek, E N

    2012-01-01

    Sensitive elements for pH-sensors created on silicon nanostructures were researched. Silicon nanostructures have been used as ion-sensitive field effect transistor (ISFET) for the measurement of solution pH. Silicon nanostructures have been fabricated by 'top-down' approach and have been studied as pH sensitive elements. Nanowires have the higher sensitivity. It was shown, that sensitive element, which is made of 'one-dimensional' silicon nanostructure have bigger pH-sensitivity as compared with 'two-dimensional' structure. Integrated element formed from two p- and n-type nanowire ISFET ('inverter') can be used as high sensitivity sensor for local relative change [H+] concentration in very small volume.

  1. Nanowire growth from the viewpoint of the thin film polylayer growth theory

    Kashchiev, Dimo

    2018-03-01

    The theory of polylayer growth of thin solid films is employed for description of the growth kinetics of single-crystal nanowires. Expressions are derived for the dependences of the height h and radius r of a given nanowire on time t, as well as for the h(r) dependence. These dependences are applicable immediately after the nanowire nucleation on the substrate and thus include the period during which the nucleated nanowire changes its shape from that of cap to that of column. The analysis shows that the nanowire cap-to-column shape transition is continuous and makes it possible to kinetically define the nanowire shape-transition radius by means of the nanowire radial and axial growth rates. The obtained h(t), r(t) and h(r) dependences are found to provide a good description of available experimental data for growth of self-nucleated GaN nanowires by the vapor-solid mechanism.

  2. Indium Arsenide Nanowires

    Madsen, Morten Hannibal

    -ray diffraction. InAs NWs can be used in a broad range of applications, including detectors, high speed electronics and low temperature transport measurements, but in this thesis focus will be put on biological experiments on living cells. Good control of Au-assisted InAs NW growth has been achieved......This thesis is about growth of Au-assisted and self-assisted InAs nanowires (NWs). The wires are synthesized using a solid source molecular beam epitaxy (MBE) system and characterized with several techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x...... by a systematic study to optimize the growth conditions; first the Au deposition, then the growth temperature and finally the beam fluxes. For further control of the growth, Au droplets have been positioned with electron beam lithography and large scale arrays with a > 99 % yield have been made on 2 inch...

  3. Self-Assembled InAs Nanowires as Optical Reflectors

    Francesco Floris

    2017-11-01

    Full Text Available Subwavelength nanostructured surfaces are realized with self-assembled vertically-aligned InAs nanowires, and their functionalities as optical reflectors are investigated. In our system, polarization-resolved specular reflectance displays strong modulations as a function of incident photon energy and angle. An effective-medium model allows one to rationalize the experimental findings in the long wavelength regime, whereas numerical simulations fully reproduce the experimental outcomes in the entire frequency range. The impact of the refractive index of the medium surrounding the nanostructure assembly on the reflectance was estimated. In view of the present results, sensing schemes compatible with microfluidic technologies and routes to innovative nanowire-based optical elements are discussed.

  4. Matrix-assisted energy conversion in nanostructured piezoelectric arrays

    Sirbuly, Donald J.; Wang, Xianying; Wang, Yinmin

    2013-01-01

    A nanoconverter is capable of directly generating electricity through a nanostructure embedded in a polymer layer experiencing differential thermal expansion in a stress transfer zone. High surface-to-volume ratio semiconductor nanowires or nanotubes (such as ZnO, silicon, carbon, etc.) are grown either aligned or substantially vertically aligned on a substrate. The resulting nanoforest is then embedded with the polymer layer, which transfers stress to the nanostructures in the stress transfer zone, thereby creating a nanostructure voltage output due to the piezoelectric effect acting on the nanostructure. Electrodes attached at both ends of the nanostructures generate output power at densities of .about.20 nW/cm.sup.2 with heating temperatures of .about.65.degree. C. Nanoconverters arrayed in a series parallel arrangement may be constructed in planar, stacked, or rolled arrays to supply power to nano- and micro-devices without use of external batteries.

  5. Enhancement of the core near-band-edge emission induced by an amorphous shell in coaxial one-dimensional nanostructure: the case of SiC/SiO{sub 2} core/shell self-organized nanowires

    Fabbri, Filippo; Rossi, Francesca; Attolini, Giovanni; Salviati, Giancarlo; Iannotta, Salvatore [IMEM-CNR Institute, Viale Usberti 37/A, I-43124 Parma (Italy); Aversa, Lucrezia; Verucchi, Roberto; Nardi, Marco [IFN-CNR Institute, Via alla Cascata 56/C-Povo, I-38123 Trento (Italy); Fukata, Naoki [International Center for Materials Nanoarchitectonics, National Institute for Materials Science and PRESTO JST, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Dierre, Benjamin; Sekiguchi, Takashi [Nano Device Characterization Group, Advanced Electronic Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2010-08-27

    We report the influence of the native amorphous SiO{sub 2} shell on the cathodoluminescence emission of 3C-SiC/SiO{sub 2} core/shell nanowires. A shell-induced enhancement of the SiC near-band-edge emission is observed and studied as a function of the silicon dioxide thickness. Since the diameter of the investigated SiC cores rules out any direct bandgap optical transitions due to confinement effects, this enhancement is ascribed to a carrier diffusion from the shell to the core, promoted by the alignment of the SiO{sub 2} and SiC bands in a type I quantum well. An accurate correlation between the optical emission and structural and SiO{sub 2}-SiC interface properties is also reported.

  6. Piezoelectric properties of zinc oxide nanowires: an ab initio study

    Korir, K K; Cicero, G; Catellani, A

    2013-01-01

    Nanowires made of materials with non-centrosymmetric crystal structures are expected to be ideal building blocks for self-powered nanodevices due to their piezoelectric properties, yet a controversial explanation of the effective operational mechanisms and size effects still delays their real exploitation. To solve this controversy, we propose a methodology based on DFT calculations of the response of nanostructures to external deformations that allows us to distinguish between the different (bulk and surface) contributions: we apply this scheme to evaluate the piezoelectric properties of ZnO [0001] nanowires, with a diameter up to 2.3 nm. Our results reveal that, while surface and confinement effects are negligible, effective strain energies, and thus the nanowire mechanical response, are dependent on size. Our unified approach allows for a proper definition of piezoelectric coefficients for nanostructures, and explains in a rigorous way the reason why nanowires are found to be more sensitive to mechanical deformation than the corresponding bulk material. (paper)

  7. Templated Control of Au nanospheres in Silica Nanowires

    Tringe, J W; Vanamu, G; Zaidi, S H

    2007-03-15

    The formation of regularly-spaced metal nanostructures in selectively-placed insulating nanowires is an important step toward realization of a wide range of nano-scale electronic and opto-electronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and reduced melting temperatures relative to templates with larger dimensions. We explain the spacing of the nanospheres with a general model based on a vapor-liquid-solid mechanism, in which an Au/Si alloy dendrite remains liquid in the nanotube until a critical Si concentration is achieved locally by silicon oxide-generated nanowire growth. Additional Si oxidation then locally reduces the surface energy of the Au-rich alloy by creating a new surface with minimum area inside of the nanotube. The isolated liquid domain subsequently evolves to become an Au nanosphere, and the process is repeated.

  8. Nanowire Photovoltaic Devices

    Forbes, David

    2015-01-01

    Firefly Technologies, in collaboration with the Rochester Institute of Technology and the University of Wisconsin-Madison, developed synthesis methods for highly strained nanowires. Two synthesis routes resulted in successful nanowire epitaxy: direct nucleation and growth on the substrate and a novel selective-epitaxy route based on nanolithography using diblock copolymers. The indium-arsenide (InAs) nanowires are implemented in situ within the epitaxy environment-a significant innovation relative to conventional semiconductor nanowire generation using ex situ gold nanoparticles. The introduction of these nanoscale features may enable an intermediate band solar cell while simultaneously increasing the effective absorption volume that can otherwise limit short-circuit current generated by thin quantized layers. The use of nanowires for photovoltaics decouples the absorption process from the current extraction process by virtue of the high aspect ratio. While no functional solar cells resulted from this effort, considerable fundamental understanding of the nanowire epitaxy kinetics and nanopatterning process was developed. This approach could, in principle, be an enabling technology for heterointegration of dissimilar materials. The technology also is applicable to virtual substrates. Incorporating nanowires onto a recrystallized germanium/metal foil substrate would potentially solve the problem of grain boundary shunting of generated carriers by restricting the cross-sectional area of the nanowire (tens of nanometers in diameter) to sizes smaller than the recrystallized grains (0.5 to 1 micron(exp 2).

  9. Functionalised Silver Nanowire Structures

    Andrew, Piers; Ilie, Adelina

    2007-01-01

    Crystalline silver nanowires 60-100 nm in diameter and tens of micrometres in length have been fabricated using a low temperature, solution synthesis technique. We explore the potential of this method to produce functional nanowire structures using two different strategies to attach active molecules to the nanowires: adsorption and displacement. Initially, as-produced silver nanowires capped with a uniaxial-growth-inducing polymer layer were functionalised by solution adsorption of a semiconducting conjugated polymer to generate fluorescent nanowire structures. The influence of nanowire surface chemistry was investigated by displacing the capping polymer with an alkanethiol self-assembled monolayer, followed by solution adsorption functionalisation. The success of molecular attachment was monitored by electron microscopy, absorption and fluorescence spectroscopy and confocal fluorescence microscopy. We examined how the optical properties of such adsorbed molecules are affected by the metallic nanowires, and observed transfer of excitation energy between dye molecules mediated by surface plasmons propagating on the nanowires. Non-contact dynamic force microscopy measurements were used to map the work-function of individual wires, revealing inhomogeneity of the polymer surface coverage

  10. Stability of Organic Nanowires

    Balzer, F.; Schiek, M.; Wallmann, I.

    2011-01-01

    The morphological stability of organic nanowires over time and under thermal load is of major importance for their use in any device. In this study the growth and stability of organic nanowires from a naphthyl end-capped thiophene grown by organic molecular beam deposition is investigated via ato...

  11. Nanowires-based light emitters on thermally and electrically conductive substrates and of making same

    Ooi, Boon S.; Zhao, Chao; Ng, Tien Khee

    2017-01-01

    Elemental or compound semiconductors on metal substrates and methods of growing them are provided. The methods can include the steps of: (i) providing a metal substrate; (ii) adding an interlayer on a surface of the metal substrate, and (iii) growing semiconductor nanowires on the interlayer using a semiconductor epitaxy growth system to form the elemental or compound semiconductor. The method can include direct growth of high quality group III-V and group III-N based materials in the form of nanowires and nanowires-based devices on metal substrates. The nanowires on all- metal scheme greatly simplifies the fabrication process of nanowires based high power light emitters.

  12. Nanowires-based light emitters on thermally and electrically conductive substrates and of making same

    Ooi, Boon S.

    2017-04-27

    Elemental or compound semiconductors on metal substrates and methods of growing them are provided. The methods can include the steps of: (i) providing a metal substrate; (ii) adding an interlayer on a surface of the metal substrate, and (iii) growing semiconductor nanowires on the interlayer using a semiconductor epitaxy growth system to form the elemental or compound semiconductor. The method can include direct growth of high quality group III-V and group III-N based materials in the form of nanowires and nanowires-based devices on metal substrates. The nanowires on all- metal scheme greatly simplifies the fabrication process of nanowires based high power light emitters.

  13. Dimensional effects in semiconductor nanowires; Dimensionseffekte in Halbleiternanodraehten

    Stichtenoth, Daniel

    2008-06-23

    Nanomaterials show new physical properties, which are determined by their size and morphology. These new properties can be ascribed to the higher surface to volume ratio, to quantum size effects or to a form anisotropy. They may enable new technologies. The nanowires studied in this work have a diameter of 4 to 400 nm and a length up to 100 {mu}m. The semiconductor material used is mainly zinc oxide (ZnO), zinc sulfide (ZnS) and gallium arsenide (GaAs). All nanowires were synthesized according to the vapor liquid solid mechanism, which was originally postulated for the growth of silicon whiskers. Respective modifications for the growth of compound semiconductor nanowires are discussed. Detailed luminescence studies on ZnO nanowires with different diameters show pronounced size effects which can be attributed to the origins given above. Similar to bulk material, a tuning of the material properties is often essential for a further functionalization of the nanowires. This is typical realized by doping the source material. It becomes apparent, that a controlled doping of nanowires during the growth process is not successful. Here an alternative method is chosen: the doping after the growth by ion implantation. However, the doping by ion implantation goes always along with the creation of crystal defects. The defects have to be annihilated in order to reach an activation of th introduced dopants. At high ion fluences and ion masses the sputtering of surface atoms becomes more important. This results in a characteristic change in the morphology of the nanowires. In detail, the doping of ZnO and ZnS nanowires with color centers (manganese and rare earth elements) is demonstrated. Especially, the intra 3d luminescence of manganese implanted ZnS nanostructures shows a strong dependence of the nanowire diameter and morphology. This dependence can be described by expanding Foersters model (which describes an energy transfer to the color centers) by a dimensional parameter

  14. Broadband THz pulse emission and transmission properties of nanostructured Pt thin films

    Hu, Mingzhe [Department of Physics and Electronics, Liupanshui Normal University, Liupanshui, Guizhou 553004 (China); College of Electronics and Information, Guizhou University, Huaxi 550025, Guiyang, Guizhou (China); Mu, Kaijun; Zhang, Cunlin [Department of Physics, Capital Normal University, Yuquan Road 100082, Beijing (China); Gu, Haoshuang, E-mail: guhs@hubu.edu.cn [Department of Electronic Sci& Tech, Hubei University, Xueyuan Road 430062, Wuhan, Hubei (China); Ding, Zhao [College of Electronics and Information, Guizhou University, Huaxi 550025, Guiyang, Guizhou (China)

    2015-10-01

    The THz transmission and emitting properties of a composite metallic nanostructure, composed of Ag nanowires electrodeposited in an anodic aluminum oxide (AAO) template and a Pt thin film, were investigated by using a femtosecond pulse laser irradiation. The microstructure of the above sub-wavelength nanostructure was investigated by XRD, SEM, AFM and TEM. The results indicated that the thickness of the Pt thin film was about 200 nm and the Ag nanowire array had a sparse and random distribution inside the AAO template, with a length distribution in the range of 10–25 μm. The THz radiation properties of above sub-wavelength nanostructure indicated that the generated THz fluence from the Pt film was a magnitude of μW scale with a broadband frequency range and its subsequent transmission could be significantly improved by the better impedance matching property of the Ag nanowire embedded AAO film compared with that of the empty AAO film.

  15. The SERS and TERS effects obtained by gold droplets on top of Si nanowires.

    Becker, M; Sivakov, V; Andrä, G; Geiger, R; Schreiber, J; Hoffmann, S; Michler, J; Milenin, A P; Werner, P; Christiansen, S H

    2007-01-01

    We show that hemispherical gold droplets on top of silicon nanowires when grown by the vapor-liquid-solid (VLS) mechanism, can produce a significant enhancement of Raman scattered signals. Signal enhancement for a few or even just single gold droplets is demonstrated by analyzing the enhanced Raman signature of malachite green molecules. For this experiment, trenches (approximately 800 nm wide) were etched in a silicon-on-insulator (SOI) wafer along crystallographic directions that constitute sidewalls ({110} surfaces) suitable for the growth of silicon nanowires in directions with the intention that the gold droplets on the silicon nanowires can meet somewhere in the trench when growth time is carefully selected. Another way to realize gold nanostructures in close vicinity is to attach a silicon nanowire with a gold droplet onto an atomic force microscopy (AFM) tip and to bring this tip toward another gold-coated AFM tip where malachite green molecules were deposited prior to the measurements. In both experiments, signal enhancement of characteristic Raman bands of malachite green molecules was observed. This indicates that silicon nanowires with gold droplets atop can act as efficient probes for tip-enhanced Raman spectroscopy (TERS). In our article, we show that a nanowire TERS probe can be fabricated by welding nanowires with gold droplets to AFM tips in a scanning electron microscope (SEM). TERS tips made from nanowires could improve the spatial resolution of Raman spectroscopy so that measurements on the nanometer scale are possible.

  16. Nano-soldering of magnetically aligned three-dimensional nanowire networks

    Gao Fan; Gu Zhiyong

    2010-01-01

    It is extremely challenging to fabricate 3D integrated nanostructures and hybrid nanoelectronic devices. In this paper, we report a simple and efficient method to simultaneously assemble and solder nanowires into ordered 3D and electrically conductive nanowire networks. Nano-solders such as tin were fabricated onto both ends of multi-segmented nanowires by a template-assisted electrodeposition method. These nanowires were then self-assembled and soldered into large-scale 3D network structures by magnetic field assisted assembly in a liquid medium with a high boiling point. The formation of junctions/interconnects between the nanowires and the scale of the assembly were dependent on the solder reflow temperature and the strength of the magnetic field. The size of the assembled nanowire networks ranged from tens of microns to millimeters. The electrical characteristics of the 3D nanowire networks were measured by regular current-voltage (I-V) measurements using a probe station with micropositioners. Nano-solders, when combined with assembling techniques, can be used to efficiently connect and join nanowires with low contact resistance, which are very well suited for sensor integration as well as nanoelectronic device fabrication.

  17. Electrical and Optical Characterization of Nanowire based Semiconductor Devices

    Ayvazian, Talin

    and optimize the electrical and optical properties of two types of nanoscale devices; in first type lithographically patterned nanowire electrodeposition (LPNE) method has been utilized to fabricate nanowire field effect transistors (NWFET) and second type involved the development of light emitting semiconductor nanowire arrays (NWLED). Field effect transistors (NWFETs) have been prepared from arrays of polycrystalline cadmium selenide (pc-CdSe) nanowires using a back gate configuration. pc-CdSe nanowires were fabricated using the lithographically patterned nanowire electrode- position (LPNE) process on SiO2 /Si substrates. After electrodeposition, pc-CdSe nanowires were thermally annealed at 300 °C x 4 h either with or without exposure to CdCl2 in methanol- a grain growth promoter. The influence of CdCl2 treatment was to increase the mean grain diameter as determined by X-ray diffraction pattern and to convert the crystal structure from cubic to wurtzite. Transfer characteristics showed an increase of the field effect mobility (mueffclose to the band gap of CdSe (1.7eV). To enhance the intensity of the emitted light and the external quantum efficiency (EQE), the distance between the contacts were reduced from 5 mum to less than 1 mum which increased the efficiency by an order of magnitude. Also, increasing the annealing temperature of nanowires from 300 °C x4 h to 450 °C x 1h enhanced grain growth confirmed by structural characterization including X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman Spectroscopy. Correspondingly the light emission intensity and EQE improved due to this grain growth. Kelvin probe force microscopy (KPFM) was utilized to understand mechanism of light emission in CdSe nanowires. Arrays of CdTe nanowires were electrodeposited using LPNE process where the elec- trodeposition of pc-CdTe was carried out at two temperatures: 20 °C (cold) and 55 °C (hot). Transmission electron microscopy (TEM) and X-ray diffraction (XRD

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

    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.

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

    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.

  20. Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

    Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

    2015-01-13

    Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

  1. Semiconductors and semimetals nanostructured systems

    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...

  2. Non-chemotoxic induction of cancer cell death using magnetic nanowires

    Contreras MF

    2015-03-01

    Full Text Available Maria F Contreras,1 Rachid Sougrat,2 Amir Zaher,3 Timothy Ravasi,1,3 Jürgen Kosel3 1Division of Biological and Environmental Sciences and Engineering, 2Advanced Nanofabrication Imaging and Characterization, 3Division of Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia Abstract: In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 µg/mL of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods. Keywords: cell death induction, low frequency alternating magnetic field, nanomedicine, nanowire internalization, nickel nanowires

  3. Optical anisotropy of quasi-1D rare-earth silicide nanostructures on Si(001)

    Chandola, S., E-mail: sandhya.chandola@isas.de [Leibniz-Institut für Analytische Wissenschaften – ISAS – e.V., Schwarzschildstraße 8, 12489 Berlin (Germany); Speiser, E.; Esser, N. [Leibniz-Institut für Analytische Wissenschaften – ISAS – e.V., Schwarzschildstraße 8, 12489 Berlin (Germany); Appelfeller, S.; Franz, M.; Dähne, M. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin (Germany)

    2017-03-31

    Highlights: • Reflectance anisotropy spectroscopy (RAS) is capable of distinguishing optically between the semiconducting wetting layer and the metallic nanowires of rare earth (Tb and Dy) silicide nanostructures grown on vicinal Si(001). • The spectra of the wetting layer show a distinctive line shape with a large peak appearing at 3.8 eV, which is assigned to the formation of 2 × 3 and 2 × 4-like subunits of the 2 × 7 reconstruction. The spectra of the metallic nanowires show peaks at the E{sub 1} and E{sub 2} transitions of bulk Si which is assigned to strong substrate strain induced by the nanowires. • The optical anisotropy of the Tb nanowires is larger than for the Dy nanowires, which is related to the preferential formation of more strained bundles as well as larger areas of clean Si surfaces in the case of Tb. • RAS is shown to be a powerful addition to surface science techniques for studying the formation of rare-earth silicide nanostructures. Its surface sensitivity and rapidity of response make it an ideal complement to the slower but higher resolution of scanning probes of STM and AFM. - Abstract: Rare earth metals are known to interact strongly with Si(001) surfaces to form different types of silicide nanostructures. Using STM to structurally characterize Dy and Tb silicide nanostructures on vicinal Si(001), it will be shown that reflectance anisotropy spectroscopy (RAS) can be used as an optical fingerprint technique to clearly distinguish between the formation of a semiconducting two-dimensional wetting layer and the metallic one-dimensional nanowires. Moreover, the distinctive spectral features can be related to structural units of the nanostructures. RAS spectra of Tb and Dy nanostructures are found to show similar features.

  4. Effect of Silicon Nanowire on Crystalline Silicon Solar Cell Characteristics

    Zahra Ostadmahmoodi Do

    2016-06-01

    Full Text Available Nanowires (NWs are recently used in several sensor or actuator devices to improve their ordered characteristics. Silicon nanowire (Si NW is one of the most attractive one-dimensional nanostructures semiconductors because of its unique electrical and optical properties. In this paper, silicon nanowire (Si NW, is synthesized and characterized for application in photovoltaic device. Si NWs are prepared using wet chemical etching method which is commonly used as a simple and low cost method for producing nanowires of the same substrate material. The process conditions are adjusted to find the best quality of Si NWs. Morphology of Si NWs is studied using a field emission scanning electron microscopic technique. An energy dispersive X-Ray analyzer is also used to provide elemental identification and quantitative compositional information. Subsequently, Schottky type solar cell samples are fabricated on Si and Si NWs using ITO and Ag contacts. The junction properties are calculated using I-V curves in dark condition and the solar cell I-V characteristics are obtained under incident of the standardized light of AM1.5. The results for the two mentioned Schottky solar cell samples are compared and discussed. An improvement in short circuit current and efficiency of Schottky solar cell is found when Si nanowires are employed.

  5. Pattern analysis of aligned nanowires in a microchannel

    Jeon, Young Jin; Kang, Hyun Wook; Ko, Seung Hwan; Sung, Hyung Jin

    2013-01-01

    An image processing method for evaluating the quality of nanowire alignment in a microchannel is described. A solution containing nanowires flowing into a microchannel will tend to deposit the nanowires on the bottom surface of the channel via near-wall shear flows. The deposited nanowires generally form complex directional structures along the direction of flow, and the physical properties of these structures depend on the structural morphology, including the alignment quality. A quantitative analysis approach to characterizing the nanowire alignment is needed to estimate the useful features of the nanowire structures. This analysis consists of several image processing methods, including ridge detection, texton analysis and autocorrelation function (ACF) calculation. The ridge detection method improved the ACF by extracting nanowire frames 1–2 pixels in width. Dilation filters were introduced to permit a comparison of the ACF results calculated from different images, regardless of the nanowire orientation. An ACF based on the FFT was then calculated over a square interrogation window. The alignment angle probability distribution was obtained using texton analysis. Monte Carlo simulations of artificially generated images were carried out, and the new algorithm was applied to images collected using two types of microscopy. (paper)

  6. Shape-dependent conversion efficiency of Si nanowire solar cells with polygonal cross-sections

    He, Yan; Yu, Wangbing; Ouyang, Gang

    2016-01-01

    A deeper insight into shape-dependent power conversion efficiency (PCE) of Si nanowire (SiNW) solar cells with polygonal cross-sectional shapes, including trigon, tetragon, hexagon, and circle, has been explored based on the atomic-bond-relaxation approach and detailed balance principle. It has been found that the surface effect induced by the loss-coordination atoms located at edges and surfaces, as well as the thermal effect, plays the dominant roles for the band shift and PCE of SiNWs due to the lattice strain occurrence at the self-equilibrium state. Our predictions are consistent with the available evidences, providing an important advance in the development of Si-based nanostructures for the desirable applications.

  7. Lasing and ion beam doping of semiconductor nanowires

    Geburt, Sebastian

    2013-01-31

    Semiconductor nanowires exhibit extraordinary optical properties like highly localized light emission, efficient waveguiding and light amplification. Even the stimulation of laser oscillations can be achieved at optical pumping, making nanowires promising for optoelectronic applications. For successful integration into future devices, three major key challenges have to be faced: (1) the understanding of the fundamental properties, (2) the modification of the emission characteristics and (3) the investigation of the efficiency-limiting factors. All key challenges are addressed in this thesis: (1) The fundamental properties of CdS nanowire have been investigated to uncover the size limits for photonic nanowire lasers. Laser oscillations were observed at room temperature and the emission characteristics were correlated to the morphology, which allowed the determination of a minimum diameter and length necessary for lasing. (2) The emission characteristics of ZnO nanowires have been successfully modified by ion beam doping with Co. The structural investigations revealed a good recovery of the ion induced damage in the crystal lattice. Optical activation of the implanted Co ions was achieved and an intense intra-3d-emission confirmed successful modification. (3) The temporal decay of excited luminescence centers strongly depends on the interplay of luminescent ions and defects, thus offering an approach to investigate the efficiency-limiting processes. Mn implanted ZnS nanowires were investigated, as the temporal decay of the incorporated Mn ions can be described by a Foerster energy transfer model modified for nanostructures. The defect concentration was varied systematically by several approaches and the model could successfully fit the transients in all cases. The emission properties of Tb implanted ZnS nanowires were investigated and the temporal decay of the intra-4f-emission could also be fitted by the model, proving its accuracy for an additional element.

  8. Lasing and ion beam doping of semiconductor nanowires

    Geburt, Sebastian

    2013-01-01

    Semiconductor nanowires exhibit extraordinary optical properties like highly localized light emission, efficient waveguiding and light amplification. Even the stimulation of laser oscillations can be achieved at optical pumping, making nanowires promising for optoelectronic applications. For successful integration into future devices, three major key challenges have to be faced: (1) the understanding of the fundamental properties, (2) the modification of the emission characteristics and (3) the investigation of the efficiency-limiting factors. All key challenges are addressed in this thesis: (1) The fundamental properties of CdS nanowire have been investigated to uncover the size limits for photonic nanowire lasers. Laser oscillations were observed at room temperature and the emission characteristics were correlated to the morphology, which allowed the determination of a minimum diameter and length necessary for lasing. (2) The emission characteristics of ZnO nanowires have been successfully modified by ion beam doping with Co. The structural investigations revealed a good recovery of the ion induced damage in the crystal lattice. Optical activation of the implanted Co ions was achieved and an intense intra-3d-emission confirmed successful modification. (3) The temporal decay of excited luminescence centers strongly depends on the interplay of luminescent ions and defects, thus offering an approach to investigate the efficiency-limiting processes. Mn implanted ZnS nanowires were investigated, as the temporal decay of the incorporated Mn ions can be described by a Foerster energy transfer model modified for nanostructures. The defect concentration was varied systematically by several approaches and the model could successfully fit the transients in all cases. The emission properties of Tb implanted ZnS nanowires were investigated and the temporal decay of the intra-4f-emission could also be fitted by the model, proving its accuracy for an additional element.

  9. Chemically synthesized metal-oxide-metal segmented nanowires with high ferroelectric response

    Herderick, Edward D; Padture, Nitin P [Department of Materials Science and Engineering, Center for Emergent Materials, Ohio State University, Columbus, OH 43210 (United States); Polomoff, Nicholas A; Huey, Bryan D, E-mail: padture.1@osu.edu [Department of Chemical, Materials, and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

    2010-08-20

    A chemical synthesis method is presented for the fabrication of high-definition segmented metal-oxide-metal (MOM) nanowires in two different ferroelectric oxide systems: Au-BaTiO{sub 3}-Au and Au-PbTiO{sub 3}-Au. This method entails electrodeposition of segmented nanowires of Au-TiO{sub 2}-Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO{sub 2} segments into BaTiO{sub 3} or PbTiO{sub 3} segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.

  10. Chemically synthesized metal-oxide-metal segmented nanowires with high ferroelectric response

    Herderick, Edward D; Padture, Nitin P; Polomoff, Nicholas A; Huey, Bryan D

    2010-01-01

    A chemical synthesis method is presented for the fabrication of high-definition segmented metal-oxide-metal (MOM) nanowires in two different ferroelectric oxide systems: Au-BaTiO 3 -Au and Au-PbTiO 3 -Au. This method entails electrodeposition of segmented nanowires of Au-TiO 2 -Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO 2 segments into BaTiO 3 or PbTiO 3 segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.

  11. Misfit-guided self-organization of anticorrelated Ge quantum dot arrays on Si nanowires.

    Kwon, Soonshin; Chen, Zack C Y; Kim, Ji-Hun; Xiang, Jie

    2012-09-12

    Misfit-strain guided growth of periodic quantum dot (QD) arrays in planar thin film epitaxy has been a popular nanostructure fabrication method. Engineering misfit-guided QD growth on a nanoscale substrate such as the small curvature surface of a nanowire represents a new approach to self-organized nanostructure preparation. Perhaps more profoundly, the periodic stress underlying each QD and the resulting modulation of electro-optical properties inside the nanowire backbone promise to provide a new platform for novel mechano-electronic, thermoelectronic, and optoelectronic devices. Herein, we report a first experimental demonstration of self-organized and self-limited growth of coherent, periodic Ge QDs on a one-dimensional Si nanowire substrate. Systematic characterizations reveal several distinctively different modes of Ge QD ordering on the Si nanowire substrate depending on the core diameter. In particular, Ge QD arrays on Si nanowires of around 20 nm diameter predominantly exhibit an anticorrelated pattern whose wavelength agrees with theoretical predictions. The correlated pattern can be attributed to propagation and correlation of misfit strain across the diameter of the thin nanowire substrate. The QD array growth is self-limited as the wavelength of the QDs remains unchanged even after prolonged Ge deposition. Furthermore, we demonstrate a direct kinetic transformation from a uniform Ge shell layer to discrete QD arrays by a postgrowth annealing process.

  12. A new approach for two-terminal electronic memory devices - Storing information on silicon nanowires

    Saranti, Konstantina; Alotaibi, Sultan; Paul, Shashi

    2016-06-01

    The work described in this paper focuses on the utilisation of silicon nanowires as the information storage element in flash-type memory devices. Silicon nanostructures have attracted attention due to interesting electrical and optical properties, and their potential integration into electronic devices. A detailed investigation of the suitability of silicon nanowires as the charge storage medium in two-terminal non-volatile memory devices are presented in this report. The deposition of the silicon nanostructures was carried out at low temperatures (less than 400 °C) using a previously developed a novel method within our research group. Two-terminal non-volatile (2TNV) memory devices and metal-insulator-semiconductor (MIS) structures containing the silicon nanowires were fabricated and an in-depth study of their characteristics was carried out using current-voltage and capacitance techniques.

  13. "High Quantum Efficiency of Band-Edge Emission from ZnO Nanowires"

    GARGAS, DANIEL; GAO, HANWEI; WANG, HUNGTA; PEIDONG, YANG

    2010-12-01

    External quantum efficiency (EQE) of photoluminescence as high as 20 percent from isolated ZnO nanowires were measured at room temperature. The EQE was found to be highly dependent on photoexcitation density, which underscores the importance of uniform optical excitation during the EQE measurement. An integrating sphere coupled to a microscopic imaging system was used in this work, which enabled the EQE measurement on isolated ZnO nanowires. The EQE values obtained here are significantly higher than those reported for ZnO materials in forms of bulk, thin films or powders. Additional insight on the radiative extraction factor of one-dimensional nanostructures was gained by measuring the internal quantum efficiency of individual nanowires. Such quantitative EQE measurements provide a sensitive, noninvasive method to characterize the optical properties of low-dimensional nanostructures and allow tuning of synthesis parameters for optimization of nanoscale materials.

  14. Dissolution-Induced Nanowire Synthesis on Hot-Dip Galvanized Surface in Supercritical Carbon Dioxide

    Aaretti Kaleva

    2017-07-01

    Full Text Available In this study, we demonstrate a rapid treatment method for producing a needle-like nanowire structure on a hot-dip galvanized sheet at a temperature of 50 °C. The processing method involved only supercritical carbon dioxide and water to induce a reaction on the zinc surface, which resulted in growth of zinc hydroxycarbonate nanowires into flower-like shapes. This artificial patina nanostructure predicts high surface area and offers interesting opportunities for its use in industrial high-end applications. The nanowires can significantly improve paint adhesion and promote electrochemical stability for organic coatings, or be converted to ZnO nanostructures by calcining to be used in various semiconductor applications.

  15. Homogeneous ZnO nanostructure arrays on GaAs substrates by two-step chemical bath synthesis

    Huang, Chun-Yuan; Wu, Tzung-Han; Cheng, Chiao-Yang; Su, Yan-Kuin

    2012-01-01

    ZnO nanostructures, including nanowires, nanorods, and nanoneedles, have been deposited on GaAs substrates by the two-step chemical bath synthesis. It was demonstrated that the O 2 -plasma treatment of GaAs substrates prior to the sol–gel deposition of seed layers was essential to conformally grow the nanostructures instead of 2D ZnO bunches and grains on the seed layers. Via adjusting the growth time and concentration of precursors, nanostructures with different average diameter (26–225 nm), length (0.98–2.29 μm), and density (1.9–15.3 × 10 9 cm −2 ) can be obtained. To the best of our knowledge, this is the first demonstration of ZnO nanostructure arrays grown on GaAs substrates by the two-step chemical bath synthesis. As an anti-reflection layer on GaAs-based solar cells, the array of ZnO nanoneedles with an average diameter of 125 nm, a moderate length of 2.29 μm, and the distribution density of 9.8 × 10 9 cm −2 has increased the power conversion efficiency from 7.3 to 12.2 %, corresponding to a 67 % improvement.

  16. Silicon nanowire hybrid photovoltaics

    Garnett, Erik C.; Peters, Craig; Brongersma, Mark; Cui, Yi; McGehee, Mike

    2010-01-01

    Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

  17. Silicon nanowire hybrid photovoltaics

    Garnett, Erik C.

    2010-06-01

    Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

  18. Synthesis, characterization, and applications of electroactive polymeric nanostructures for organic coatings

    Suryawanshi, Abhijit Jagnnath

    Electroactive polymers (EAP) such as polypyrrole (PPy) and polyaniline (PANI) are being explored intensively in the scientific community. Nanostructures of EAPs have low dimensions and high surface area enabling them to be considered for various useful applications. These applications are in several fields including corrosion inhibition, capacitors, artificial muscles, solar cells, polymer light emitting diodes, and energy storage devices. Nanostructures of EAPs have been synthesized in different morphologies such as nanowires, nanorods, nanotubes, nanospheres, and nanocapsules. This variety in morphology is traditionally achieved using soft templates, such as surfactant micelles, or hard templates, such as anodized aluminum oxide (AAO). Templates provide stability and groundwork from which the polymer can grow, but the templates add undesirable expense to the process and can change the properties of the nanoparticles by integrating its own properties. In this study a template free method is introduced to synthesize EAP nanostructures of PPy and PANI utilizing ozone oxidation. The simple techniques involve ozone exposure to the monomer solution to produce aqueous dispersions of EAP nanostructures. The synthesized nanostructures exhibit uniform morphology, low particle size distribution, and stability against agglomeration. Ozone oxidation is further explored for the synthesis of silver-PPy (Ag-PPy) core-shell nanospheres (CSNs). Coatings containing PPy nanospheres were formulated to study the corrosion inhibition efficiency of PPy nanospheres. Investigation of the coatings using electrochemical techniques revealed that the PPy nanospheres may provide corrosion inhibition against filiform corrosion by oxygen scavenging mechanism. Finally, organic corrosion inhibitors were incorporated in PPy to develop efficient corrosion inhibiting systems, by using the synergistic effects from PPy and organic corrosion inhibitors.

  19. Study of spin dynamics and damping on the magnetic nanowire arrays with various nanowire widths

    Cho, Jaehun [Department of Physics, Inha University, Incheon, 402-751 (Korea, Republic of); Fujii, Yuya; Konioshi, Katsunori [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Yoon, Jungbum [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Kim, Nam-Hui; Jung, Jinyong [Department of Physics, Inha University, Incheon, 402-751 (Korea, Republic of); Miwa, Shinji [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Jung, Myung-Hwa [Department of Physics, Sogang University, Seoul, 121-742 (Korea, Republic of); Suzuki, Yoshishige [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); You, Chun-Yeol, E-mail: cyyou@inha.ac.kr [Department of Physics, Inha University, Incheon, 402-751 (Korea, Republic of)

    2016-07-01

    We investigate the spin dynamics including Gilbert damping in the ferromagnetic nanowire arrays. We have measured the ferromagnetic resonance of ferromagnetic nanowire arrays using vector-network analyzer ferromagnetic resonance (VNA-FMR) and analyzed the results with the micromagnetic simulations. We find excellent agreement between the experimental VNA-FMR spectra and micromagnetic simulations result for various applied magnetic fields. We find that the same tendency of the demagnetization factor for longitudinal and transverse conditions, N{sub z} (N{sub y}) increases (decreases) as increasing the nanowire width in the micromagnetic simulations while N{sub x} is almost zero value in transverse case. We also find that the Gilbert damping constant increases from 0.018 to 0.051 as the increasing nanowire width for the transverse case, while it is almost constant as 0.021 for the longitudinal case. - Highlights: • We investigate the spin dynamic properties in the ferromagnetic nanowire arrays. • The demagnetization factors have similar tendency with the prism geometry results. • The Gilbert damping constant is increased from 0.018 to 0.051 as the increasing nanowire width for the transverse. • The Gilbert damping constant is almost constant as 0.021 for the longitudinal case.

  20. Electrodeposition of ZnO nano-wires lattices with a controlled morphology

    Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C.

    2006-01-01

    In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO 2 . Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

  1. Nickel Nanowire@Porous NiCo2O4 Nanorods Arrays Grown on Nickel Foam as Efficient Pseudocapacitor Electrode

    Houzhao Wan

    2017-12-01

    Full Text Available A three dimensional hierarchical nanostructure composed of nickel nanowires and porous NiCo2O4 nanorods arrays on the surface of nickel foam is successfully fabricated by a facile route. In this structure, the nickel nanowires are used as core materials to support high-pseudocapacitance NiCo2O4 nanorods and construct the well-defined NiCo2O4 nanorods shell/nickel nanowires core hierarchical structure on nickel foam. Benefiting from the participation of nickel nanowires, the nickel nanowire@NiCo2O4/Ni foam electrode shows a high areal specific capacitance (7.4 F cm−2 at 5 mA cm−2, excellent rate capability (88.04% retained at 100 mA cm−2, and good cycling stability (74.08% retained after 1,500 cycles. The superior electrochemical properties made it promising as electrode for supercapacitors.

  2. Nitrogen and Fluorine-Codoped Carbon Nanowire Aerogels as Metal-Free Electrocatalysts for Oxygen Reduction Reaction

    Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Xiao, Biwei [Energy and Environmental Directory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA

    2017-07-11

    The development of active, durable, and low-cost catalysts to replace noble metal-based materials is highly desirable to promote the sluggish oxygen reduction reaction in fuel cells. Herein, nitrogen and fluorine-codoped three-dimensional carbon nanowire aerogels, composed of interconnected carbon nanowires, were synthesized for the first time by a hydrothermal carbonization process. Owing to their porous nanostructures and heteroatom-doping, the as-prepared carbon nanowire aerogels, with optimized composition, present excellent electrocatalytic activity that is comparable to commercial Pt/C. Remarkably, the aerogels also exhibit superior stability and methanol tolerance. This synthesis procedure paves a new way to design novel heteroatomdoped catalysts.

  3. Towards large-scale plasma-assisted synthesis of nanowires

    Cvelbar, U.

    2011-05-01

    Large quantities of nanomaterials, e.g. nanowires (NWs), are needed to overcome the high market price of nanomaterials and make nanotechnology widely available for general public use and applications to numerous devices. Therefore, there is an enormous need for new methods or routes for synthesis of those nanostructures. Here plasma technologies for synthesis of NWs, nanotubes, nanoparticles or other nanostructures might play a key role in the near future. This paper presents a three-dimensional problem of large-scale synthesis connected with the time, quantity and quality of nanostructures. Herein, four different plasma methods for NW synthesis are presented in contrast to other methods, e.g. thermal processes, chemical vapour deposition or wet chemical processes. The pros and cons are discussed in detail for the case of two metal oxides: iron oxide and zinc oxide NWs, which are important for many applications.

  4. Nanowire Electrodes for Advanced Lithium Batteries

    Huang, Lei; Wei, Qiulong; Sun, Ruimin; Mai, Liqiang, E-mail: mlq518@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, WUT-Harvard Joint Nano Key Laboratory, Wuhan University of Technology, Wuhan (China)

    2014-10-27

    Since the commercialization of lithium ion batteries (LIBs) in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism need to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate that the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reaction limit the cycling performance of LIBs. Based on the in situ observations, some feasible optimization strategies, including prelithiation, coaxial structure, nanowire arrays, and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some “beyond Li-ion” batteries, such as Li-S and Li-air batteries are also described.

  5. Growth Mechanism of Nanowires: Ternary Chalcogenides

    Singh, N. B.; Coriell, S. R.; Hopkins, R. H.; Su, Ching Hua; Arnold, B.; Choa, Fow-Sen; Cullum, Brian

    2016-01-01

    In the past two decades there has been a large rise in the investment and expectations for nanotechnology use. Almost every area of research has projected improvements in sensors, or even a promise for the emergence of some novel device technologies. For these applications major focuses of research are in the areas of nanoparticles and graphene. Although there are some near term applications with nanowires in photodetectors and other low light detectors, there are few papers on the growth mechanism and fabrication of nanowire-based devices. Semiconductor nanowires exhibit very favorable and promising optical properties, including high transparency and a several order of magnitude better photocurrent than thin film and bulk materials. We present here an overview of the mechanism of nanowire growth from the melt, and some preliminary results for the thallium arsenic selenide material system. Thallium arsenic selenide (TAS) is a multifunctional material combining excellent acousto-optical, nonlinear and radiation detection properties. We observed that small units of (TAS) nanocubes arrange and rearrange at moderate melt undercooling to form the building block of a nanowire. In some cases very long wires (less than mm) are formed. Since we avoided the catalyst, we observed self-nucleation and uncontrolled growth of wires from different places.

  6. Nanowire Electrodes for Advanced Lithium Batteries

    Lei eHuang

    2014-10-01

    Full Text Available Since the commercialization of lithium ion batteries (LIBs in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism needs to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reactions which limit the cycling performance of LIBs. Based on the in situ observations, some feasible structure architecture strategies, including prelithiation, coaxial structure, nanowire arrays and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some beyond Li-ion batteries, such as Li-S and Li-air battery, are also described.

  7. Nanowire Electrodes for Advanced Lithium Batteries

    Huang, Lei; Wei, Qiulong; Sun, Ruimin; Mai, Liqiang

    2014-01-01

    Since the commercialization of lithium ion batteries (LIBs) in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism need to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate that the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reaction limit the cycling performance of LIBs. Based on the in situ observations, some feasible optimization strategies, including prelithiation, coaxial structure, nanowire arrays, and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some “beyond Li-ion” batteries, such as Li-S and Li-air batteries are also described.

  8. Facile Hydrothermal Preparation of ZNO/CO3O4 Heterogeneous Nanostructures and its Photovoltaic Effect

    Wei, Fanan; Jiang, Minlin; Liu, Lianqing

    2015-07-01

    Photovoltaic technology offers great potential in the replacement of fossil fuel resources, but still suffers from high device fabrication cost. Herein, we attempted to provide a solution to these issues with heterogeneous nanostructures. Firstly, Zinc oxide (ZnO)/cobalt oxide (Co3O4) heterojunction nanowires are prepared through facile fabrication methods. By assembling Co(OH)2 nanoplates on ZnO nanowire arrays, the ZnO/Co3O4 heterogeneous nanostructures are uniformly synthesized on ITO coated glass and wafer. Current (I)-voltage (V) measurement through conductive atomic force microscope shows excellent photovoltaic effect. And, the heterojunction nanostructures shows unprecedented high open circuit voltage. Therefore, the potential application of the heterogeneous nanostructures in solar cells is demonstrated.

  9. Photo-driven autonomous hydrogen generation system based on hierarchically shelled ZnO nanostructures

    Kim, Heejin; Yong, Kijung

    2013-01-01

    A quantum dot semiconductor sensitized hierarchically shelled one-dimensional ZnO nanostructure has been applied as a quasi-artificial leaf for hydrogen generation. The optimized ZnO nanostructure consists of one dimensional nanowire as a core and two-dimensional nanosheet on the nanowire surface. Furthermore, the quantum dot semiconductors deposited on the ZnO nanostructures provide visible light harvesting properties. To realize the artificial leaf, we applied the ZnO based nanostructure as a photoelectrode with non-wired Z-scheme system. The demonstrated un-assisted photoelectrochemical system showed the hydrogen generation properties under 1 sun condition irradiation. In addition, the quantum dot modified photoelectrode showed 2 mA/cm 2 current density at the un-assisted condition

  10. Nanotubes and nanowires

    Unknown

    junction nanotubes by the pyrolysis of appropriate organic precursors. ... By making use of carbon nanotubes, nanowires of metals, metal ..... The use of activated carbon in place of ..... required for the complete removal of the carbon template.

  11. Electrical conductivity characteristic of TiO2 nanowires from hydrothermal method

    Othman, Mohd Azlishah; Amat, Noor Faridah; Ahmad, Badrul Hisham; Rajan, Jose

    2014-01-01

    One dimensional nanostructures of titanium dioxide (TiO 2 ) were synthesized via hydrothermal method by mixing TiO 2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ∼15 nm. TiO 2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO 2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO 2 nanowires was determined by measuring the resistance of the TiO 2 nanowires paste on microscope glass.

  12. Transport and structural characterization of solution-processable doped ZnO nanowires

    Noriega, Rodrigo

    2009-08-18

    The use of ZnO nanowires has become a widespread topic of interest in optoelectronics. In order to correctly assess the quality, functionality, and possible applications of such nanostructures it is important to accurately understand their electrical and optical properties. Aluminum- and gallium-doped crystalline ZnO nanowires were synthesized using a low-temperature solution-based process, achieving dopant densities of the order of 1020 cm-3. A non-contact optical technique, photothermal deflection spectroscopy, is used to characterize ensembles of ZnO nanowires. By modeling the free charge carrier absorption as a Drude metal, we are able to calculate the free carrier density and mobility. Determining the location of the dopant atoms in the ZnO lattice is important to determine the doping mechanisms of the ZnO nanowires. Solid-state NMR is used to distinguish between coordination environments of the dopant atoms.

  13. A comprehensive study of thermoelectric and transport properties of β-silicon carbide nanowires

    Valentín, L. A.; Betancourt, J.; Fonseca, L. F., E-mail: luis.fonseca@upr.edu [Department of Physics University of Puerto Rico, Rio Piedras (Puerto Rico); Pettes, M. T.; Shi, L. [Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712 (United States); Soszyński, M.; Huczko, A. [Department of Chemistry, Warsaw University, Pasteur 1 Str., 02-093 Warsaw (Poland)

    2013-11-14

    The temperature dependence of the Seebeck coefficient, the electrical and thermal conductivities of individual β-silicon carbide nanowires produced by combustion in a calorimetric bomb were studied using a suspended micro-resistance thermometry device that allows four-point probe measurements to be conducted on each nanowire. Additionally, crystal structure and growth direction for each measured nanowire was directly obtained by transmission electron microscopy analysis. The Fermi level, the carrier concentration, and mobility of each nanostructure were determined using a combination of Seebeck coefficient and electrical conductivity measurements, energy band structure and transport theory calculations. The temperature dependence of the thermal and electrical conductivities of the nanowires was explained in terms of contributions from boundary, impurity, and defect scattering.

  14. Control of the ZnO nanowires nucleation site using microfluidic channels.

    Lee, Sang Hyun; Lee, Hyun Jung; Oh, Dongcheol; Lee, Seog Woo; Goto, Hiroki; Buckmaster, Ryan; Yasukawa, Tomoyuki; Matsue, Tomokazu; Hong, Soon-Ku; Ko, HyunChul; Cho, Meoung-Whan; Yao, Takafumi

    2006-03-09

    We report on the growth of uniquely shaped ZnO nanowires with high surface area and patterned over large areas by using a poly(dimethylsiloxane) (PDMS) microfluidic channel technique. The synthesis uses first a patterned seed template fabricated by zinc acetate solution flowing though a microfluidic channel and then growth of ZnO nanowire at the seed using thermal chemical vapor deposition on a silicon substrate. Variations the ZnO nanowire by seed pattern formed within the microfluidic channel were also observed for different substrates and concentrations of the zinc acetate solution. The photocurrent properties of the patterned ZnO nanowires with high surface area, due to their unique shape, were also investigated. These specialized shapes and patterning technique increase the possibility of realizing one-dimensional nanostructure devices such as sensors and optoelectric devices.

  15. Single-crystalline self-branched anatase titania nanowires for dye-sensitized solar cells

    Li, Zhenquan; Yang, Huang; Wu, Fei; Fu, Jianxun; Wang, Linjun; Yang, Weiguang

    2017-03-01

    The morphology of the anatase titania plays an important role in improving the photovoltaic performance in dye-sensitized solar cells. In this work, single-crystalline self-branched anatase TiO2 nanowires have been synthesized by hydrothermal method using TBAH and CTAB as morphology controlling agents. The obtained self-branched TiO2 nanowires dominated by a large percentage of (010) facets. The photovoltaic conversion efficiency (6.37%) of dye-sensitized solar cell (DSSC) based on the self-branched TiO2 nanowires shows a significant improvement (26.6%) compared to that of P25 TiO2 (5.03%). The enhanced performance of the self-branched TiO2 nanowires-based DSSC is due to heir large percent of exposed (010) facets which have strong dye adsorption capacity and effective charge transport of the self-branched 1D nanostructures.

  16. Facile synthesis of polypyrrole nanowires for high-performance supercapacitor electrode materials

    Junhong Zhao

    2016-06-01

    Full Text Available Polypyrrole nanowires are facile synthesized under a mild condition with FeCl3 as an oxidant. Polypyrrole nanowires with the width of 120 nm form many nanogaps or pores due to the intertwined nanostructures. More importantly, PPy nanowires were further applied for supercapacitor electrode materials. After electrochemical testing, it was observed that the PPy nanowire based electrode showed a large specific capacitance (420 F g−1, 1.5 A g−1 and good rate capability (272 F g−1, 18.0 A g−1, which is larger than that of most of published results. The as-prepared electrode can work well even after 8000 cycles at 1.5 A g−1.

  17. Formation of self-ordered porous anodized alumina template for growing tungsten trioxide nanowires

    Hussain, Tajamal; Shah, Asma Tufail; Shehzad, Khurram; Mujahid, Adnan; Farooqi, Zahoor Hussain; Raza, Muhammad Hamid; Ahmed, Mirza Nadeem; Nisa, Zaib Un

    2015-12-01

    Uniform porous anodized aluminum oxide (AAO) membrane has been synthesized by two-step anodization for fabricating tungsten trioxide (WO3) nanowires. Under assayed conditions, uniform porous structure of alumina (Al2O3) membrane with long range ordered hexagonal arrangements of nanopores was achieved. The self-assembled template possesses pores of internal diameter of 50 nm and interpore distance ( d int) of 80 nm with a thickness of about 80 µm, i.e., used for fabrication of nanostructures. WO3 nanowires have been fabricated by simple electroless deposition method inside Al2O3 nanopores. SEM images show tungsten trioxide nanowire with internal diameter of about 50 nm, similar to porous diameter of AAO template. XRD results showed that nanowires exist in cubic crystalline state with minor proportion of monoclinic phase.

  18. ZrTiO4 nanowire growth using membrane-assisted Pechini route

    P. R. de Lucena

    2014-11-01

    Full Text Available The high surface-to-volume ratio of nanowires makes them natural competitors as new device components. In this regard, a current major challenge is to produce quasi-one-dimensional nanostructures composed of well established oxide-based materials. This article reports the synthesis of ZrTiO4 nanowires on a silicon (100 wafer in a single-step deposition/thermal treatment. The template-directed membrane synthesis strategy was associated with the Pechini route and spin-coating deposition technique. ZrTiO4 nanowires were obtained at 700 ˚C with diameters in the range of 80-100 nm. FEG- SEM images were obtained to investigate ZrTiO4 nanowire formation on the silicon surface and energy dispersive x-ray detection (EDS and x-ray diffraction (XRD analyses were performed to confirm the oxide composition and structure.

  19. ZrTiO4 Nanowire Growth Using Membrane-assisted Pechini Route

    Poty Rodrigues de Lucena

    2016-02-01

    Full Text Available The high surface-to-volume ratio of nanowires makes them natural competitors as newer device components. In this regard, a current major challenge is to produce quasi-one-dimensional nanostructures composed of well-established oxide-based materials. This article reports the synthesis of ZrTiO4 nanowires on a silicon (100 wafer in a single-step deposition/thermal treatment. The template-directed membrane synthesis strategy was associated with the Pechini route and spin-coating deposition technique. ZrTiO4 nanowires were obtained at 700 °C with diameters in the range of 80-100 nm. FEGSEM images were obtained to investigate ZrTiO4 nanowire formation on the silicon surface and energy dispersive X-ray detection (EDS and X-ray diffraction (XRD analyses were performed to confirm the oxide composition and structure. 

  20. David Adler Lectureship Award Talk: III-V Semiconductor Nanowires on Silicon for Future Devices

    Riel, Heike

    Bottom-up grown nanowires are very attractive materials for direct integration of III-V semiconductors on silicon thus opening up new possibilities for the design and fabrication of nanoscale devices for electronic, optoelectronic as well as quantum information applications. Template-Assisted Selective Epitaxy (TASE) allows the well-defined and monolithic integration of complex III-V nanostructures and devices on silicon. Achieving atomically abrupt heterointerfaces, high crystal quality and control of dimension down to 1D nanowires enabled the demonstration of FETs and tunnel devices based on In(Ga)As and GaSb. Furthermore, the strong influence of strain on nanowires as well as results on quantum transport studies of InAs nanowires with well-defined geometry will be presented.

  1. Optical polarization properties of InAs/InP quantum dot and quantum rod nanowires

    Anufriev, Roman; Bru-Chevallier, Catherine; Chauvin, Nicolas; Barakat, Jean-Baptiste; Letartre, Xavier; Gendry, Michel; Patriarche, Gilles; Harmand, Jean-Christophe

    2015-01-01

    The emission polarization of single InAs/InP quantum dot (QD) and quantum rod (QR) nanowires is investigated at room temperature. Whereas the emission of the QRs is mainly polarized parallel to the nanowire axis, the opposite behavior is observed for the QDs. These optical properties can be explained by a combination of dielectric effects related to the nanowire geometry and to the configuration of the valence band in the nanostructure. A theoretical model and finite difference in time domain calculations are presented to describe the impact of the nanowire and the surroundings on the optical properties of the emitter. Using this model, the intrinsic degree of linear polarization of the two types of emitters is extracted. The strong polarization anisotropies indicate a valence band mixing in the QRs but not in the QDs. (paper)

  2. High thermoelectric properties of (Sb, Bi)2Te3 nanowire arrays by tilt-structure engineering

    Tan, Ming; Hao, Yanming; Deng, Yuan; Chen, Jingyi

    2018-06-01

    In this paper, we present an innovative tilt-structure design concept for (Sb, Bi)2Te3 nanowire array assembled by high-quality nanowires with well oriented growth, utilizing a simple vacuum thermal evaporation technique. The unusual tilt-structure (Sb, Bi)2Te3 nanowire array with a tilted angle of 45° exhibits a high thermoelectric dimensionless figure-of-merit ZT = 1.72 at room temperature. The relatively high ZT value in contrast to that of previously reported (Sb, Bi)2Te3 materials and the vertical (Sb, Bi)2Te3 nanowire arrays evidently reveals the crucial role of the unique tilt-structure in favorably influencing carrier and phonon transport properties, resulting in a significantly improved ZT value. The transport mechanism of such tilt-structure is proposed and investigated. This method opens a new approach to optimize nano-structure in thin films for next-generation thermoelectric materials and devices.

  3. Large-scale fabrication of vertically aligned ZnO nanowire arrays

    Wang, Zhong L; Das, Suman; Xu, Sheng; Yuan, Dajun; Guo, Rui; Wei, Yaguang; Wu, Wenzhuo

    2013-02-05

    In a method for growing a nanowire array, a photoresist layer is placed onto a nanowire growth layer configured for growing nanowires therefrom. The photoresist layer is exposed to a coherent light interference pattern that includes periodically alternately spaced dark bands and light bands along a first orientation. The photoresist layer exposed to the coherent light interference pattern along a second orientation, transverse to the first orientation. The photoresist layer developed so as to remove photoresist from areas corresponding to areas of intersection of the dark bands of the interference pattern along the first orientation and the dark bands of the interference pattern along the second orientation, thereby leaving an ordered array of holes passing through the photoresist layer. The photoresist layer and the nanowire growth layer are placed into a nanowire growth environment, thereby growing nanowires from the nanowire growth layer through the array of holes.

  4. Biofunctionalized Magnetic Nanowires

    Kosel, Jurgen

    2013-12-19

    Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

  5. Biofunctionalized Magnetic Nanowires

    Kosel, Jü rgen; Ravasi, Timothy; Contreras Gerenas, Maria Fernanda

    2013-01-01

    Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

  6. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    Arghya Narayan Banerjee

    2011-02-01

    Full Text Available Arghya Narayan BanerjeeSchool of Mechanical Engineering, Yeungnam University, Gyeongsan, South KoreaAbstract: Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via

  7. Potential of AlN nanostructures as hydrogen storage materials.

    Wang, Qian; Sun, Qiang; Jena, Puru; Kawazoe, Yoshiyuki

    2009-03-24

    The capability of AlN nanostructures (nanocages, nanocones, nanotubes, and nanowires) to store hydrogen has been studied using gradient-corrected density functional theory. In contrast to bulk AlN, which has the wurtzite structure and four-fold coordination, the Al sites in AlN nanostructures are unsaturated and have two- and three-fold coordination. Each Al atom is capable of binding one H(2) molecule in quasi-molecular form, leading to 4.7 wt % hydrogen, irrespective of the topology of the nanostructures. With the exception of AlN nanotubes, energetics does not support the adsorption of additional hydrogen. The binding energies of hydrogen to these unsaturated metal sites lie in the range of 0.1-0.2 eV/H(2) and are ideal for applications under ambient thermodynamic conditions. Furthermore, these materials do not suffer from the clustering problem that often plagues metal-coated carbon nanostructures.

  8. Hierarchical 3C-SiC nanowires as stable photocatalyst for organic dye degradation under visible light irradiation

    Zhang, Judong; Chen, Jianjun; Xin, Lipeng; Wang, Mingming

    2014-01-01

    Graphical abstract: The photocatalytic performance was enhanced by hierarchical nanostructural SiC nanowires due to the increased specific surface areas and efficient incident light scattering. The positive effect of SiO 2 layer growth on the surface of nanowires during the catalytic process on the high decolorization efficiency of SiC nanowires was attributed to SiO 2 surface oxygen vacancies. -- Highlights: • High decolorization rate of methylene blue using hierarchical 3C-SiC nanowires was obtained. • The effect of methylene blue with different concentration to catalytic result was investigated. • The photocatalytic reaction mechanism of degrading methylene blue was explained. • The SiO 2 layer generating on nanowire surface in the catalytic process was analyzed. -- Abstract: 3C-SiC nanowires with hierarchical structure were synthesized by sol–gel carbothermal reduction method. The photocatalytic property of SiC nanowires was investigated. 3C-SiC hierarchical nanowires exhibited an enhanced photocatalytic activity by accelerating the photocatalytic degradation of methylene blue solution under visible light irradiation. Methylene blue was degraded efficiently after 5 h irradiation over the photocatalyst. The photocatalytic activity was affected by the initial concentration of the methylene blue solution. Silicon dioxide layer was observed on the surface of nanowires after the catalytic process. The positive effect of SiO 2 surface oxygen vacancies and 3C-SiC hierarchical nanostructures on the high decolorization efficiency of SiC nanowires was discussed. The detailed photocatalytic redox processes were also explained

  9. Toward optimized light utilization in nanowire arrays using scalable nanosphere lithography and selected area growth.

    Madaria, Anuj R; Yao, Maoqing; Chi, Chunyung; Huang, Ningfeng; Lin, Chenxi; Li, Ruijuan; Povinelli, Michelle L; Dapkus, P Daniel; Zhou, Chongwu

    2012-06-13

    Vertically aligned, catalyst-free semiconducting nanowires hold great potential for photovoltaic applications, in which achieving scalable synthesis and optimized optical absorption simultaneously is critical. Here, we report combining nanosphere lithography (NSL) and selected area metal-organic chemical vapor deposition (SA-MOCVD) for the first time for scalable synthesis of vertically aligned gallium arsenide nanowire arrays, and surprisingly, we show that such nanowire arrays with patterning defects due to NSL can be as good as highly ordered nanowire arrays in terms of optical absorption and reflection. Wafer-scale patterning for nanowire synthesis was done using a polystyrene nanosphere template as a mask. Nanowires grown from substrates patterned by NSL show similar structural features to those patterned using electron beam lithography (EBL). Reflection of photons from the NSL-patterned nanowire array was used as a measure of the effect of defects present in the structure. Experimentally, we show that GaAs nanowires as short as 130 nm show reflection of <10% over the visible range of the solar spectrum. Our results indicate that a highly ordered nanowire structure is not necessary: despite the "defects" present in NSL-patterned nanowire arrays, their optical performance is similar to "defect-free" structures patterned by more costly, time-consuming EBL methods. Our scalable approach for synthesis of vertical semiconducting nanowires can have application in high-throughput and low-cost optoelectronic devices, including solar cells.

  10. High photoresponse of individual WS2 nanowire-nanoflake hybrid materials

    Asres, Georgies Alene; Järvinen, Topias; Lorite, Gabriela S.; Mohl, Melinda; Pitkänen, Olli; Dombovari, Aron; Tóth, Geza; Spetz, Anita Lloyd; Vajtai, Robert; Ajayan, Pulickel M.; Lei, Sidong; Talapatra, Saikat; Kordas, Krisztian

    2018-06-01

    van der Waals solids have been recognized as highly photosensitive materials that compete conventional Si and compound semiconductor based devices. While 2-dimensional nanosheets of single and multiple layers and 1-dimensional nanowires of molybdenum and tungsten chalcogenides have been studied, their nanostructured derivatives with complex morphologies are not explored yet. Here, we report on the electrical and photosensitive properties of WS2 nanowire-nanoflake hybrid materials we developed lately. We probe individual hybrid nanostructured particles along the structure using focused ion beam deposited Pt contacts. Further, we use conductive atomic force microscopy to analyze electrical behavior across the nanostructure in the transverse direction. The electrical measurements are complemented by in situ laser beam illumination to explore the photoresponse of the nanohybrids in the visible optical spectrum. Photodetectors with responsivity up to ˜0.4 AW-1 are demonstrated outperforming graphene as well as most of the other transition metal dichalcogenide based devices.

  11. Review of Fabrication Methods, Physical Properties, and Applications of Nanostructured Copper Oxides Formed via Electrochemical Oxidation

    Wojciech J. Stepniowski

    2018-05-01

    Full Text Available Typically, anodic oxidation of metals results in the formation of hexagonally arranged nanoporous or nanotubular oxide, with a specific oxidation state of the transition metal. Recently, the majority of transition metals have been anodized; however, the formation of copper oxides by electrochemical oxidation is yet unexplored and offers numerous, unique properties and applications. Nanowires formed by copper electrochemical oxidation are crystalline and composed of cuprous (CuO or cupric oxide (Cu2O, bringing varied physical and chemical properties to the nanostructured morphology and different band gaps: 1.44 and 2.22 eV, respectively. According to its Pourbaix (potential-pH diagram, the passivity of copper occurs at ambient and alkaline pH. In order to grow oxide nanostructures on copper, alkaline electrolytes like NaOH and KOH are used. To date, no systemic study has yet been reported on the influence of the operating conditions, such as the type of electrolyte, its temperature, and applied potential, on the morphology of the grown nanostructures. However, the numerous reports gathered in this paper will provide a certain view on the matter. After passivation, the formed nanostructures can be also post-treated. Post-treatments employ calcinations or chemical reactions, including the chemical reduction of the grown oxides. Nanostructures made of CuO or Cu2O have a broad range of potential applications. On one hand, with the use of surface morphology, the wetting contact angle is tuned. On the other hand, the chemical composition (pure Cu2O and high surface area make such materials attractive for renewable energy harvesting, including water splitting. While compared to other fabrication techniques, self-organized anodization is a facile, easy to scale-up, time-efficient approach, providing high-aspect ratio one-dimensional (1D nanostructures. Despite these advantages, there are still numerous challenges that have to be faced, including the

  12. Brownian motion of tethered nanowires.

    Ota, Sadao; Li, Tongcang; Li, Yimin; Ye, Ziliang; Labno, Anna; Yin, Xiaobo; Alam, Mohammad-Reza; Zhang, Xiang

    2014-05-01

    Brownian motion of slender particles near a boundary is ubiquitous in biological systems and in nanomaterial assembly, but the complex hydrodynamic interaction in those systems is still poorly understood. Here, we report experimental and computational studies of the Brownian motion of silicon nanowires tethered on a substrate. An optical interference method enabled direct observation of microscopic rotations of the slender bodies in three dimensions with high angular and temporal resolutions. This quantitative observation revealed anisotropic and angle-dependent hydrodynamic wall effects: rotational diffusivity in inclined and azimuth directions follows different power laws as a function of the length, ∼ L(-2.5) and ∼ L(-3), respectively, and is more hindered for smaller inclined angles. In parallel, we developed an implicit simulation technique that takes the complex wire-wall hydrodynamic interactions into account efficiently, the result of which agreed well with the experimentally observed angle-dependent diffusion. The demonstrated techniques provide a platform for studying the microrheology of soft condensed matters, such as colloidal and biological systems near interfaces, and exploring the optimal self-assembly conditions of nanostructures.

  13. Localization and Related Phenomena in Multiply Connected Nanostructured Inverse Opal Bismuth

    Bleiweiss, Michael; Saygi, Salih; Amirzadeh, Jafar; Datta, Timir; Lungu, Anca; Yin, Ming; Palm, Eric; Brandt, Bruce; Iqbal, Zafar

    2001-03-01

    The nanostructures were fabricated by pressure infiltration of bismuth into porous artificial opal and were characterized using SEM, EDX and XRD. These structures form a regular three-dimensional network in which the bismuth regions percolate in all directions between the close packed spheres of SiO_2. The sizes of the conducting regions are of the order of tens of nanometers. The static magnetic properties of both bismuth inverse opal and bulk bismuth were studied using a SQUID magnetometer. Transport measurements, including Hall, were done using standard ac four and six probe techniques in fields up to 17 T* and temperatures between 4.2 and 150 K. The results of these measurements, including the observation of localization phenomena, will be discussed. Comparisons will be made with published results on bismuth nanowires. *Performed at the National High Magnetic Field Lab (NHMFL) FSU, Tallahassee, FL. Partially supported by a grant from NASA.

  14. Fabrication of Nano-Micro Hybrid Structures by Replication and Surface Treatment of Nanowires

    Yeonho Jeong

    2017-07-01

    Full Text Available Nanowire structures have attracted attention in various fields, since new characteristics could be acquired in minute regions. Especially, Anodic Aluminum Oxide (AAO is widely used in the fabrication of nanostructures, which has many nanosized pores and well-organized nano pattern. Using AAO as a template for replication, nanowires with a very high aspect ratio can be fabricated. Herein, we propose a facile method to fabricate a nano-micro hybrid structure using nanowires replicated from AAO, and surface treatment. A polymer resin was coated between Polyethylene terephthalate (PET and the AAO filter, roller pressed, and UV-cured. After the removal of aluminum by using NaOH solution, the nanowires aggregated to form a micropattern. The resulting structure was subjected to various surface treatments to investigate the surface behavior and wettability. As opposed to reported data, UV-ozone treatment can enhance surface hydrophobicity because the UV energy affects the nanowire surface, thus altering the shape of the aggregated nanowires. The hydrophobicity of the surface could be further improved by octadecyltrichlorosilane (OTS coating immediately after UV-ozone treatment. We thus demonstrated that the nano-micro hybrid structure could be formed in the middle of nanowire replication, and then, the shape and surface characteristics could be controlled by surface treatment.

  15. Structural characterization of Fe−Pd nanowires grown by electrodeposition using an acid electrolyte

    Domenichini, P. [Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Condó, A.M. [Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Haberkorn, N., E-mail: nhaberk@cab.cnea.gov.ar [Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina)

    2016-07-01

    Fe{sub 70}Pd{sub 30} nanostructures have potential application in actuators due to their conventional and magnetic shape memory. Here, we report the microstructure of electrodeposition grown Fe−Pd nanowires in which the process was confined to polycarbonate membranes with a nominal pore diameter of 200 nm. We used an acid electrolyte (pH ≈ 5) in which the solution was stabilized with sulfosalicylic acid. The average chemical concentration of the nanowires can be systematically shifted from rich palladium to rich iron by changing the growth potential. The study of the microstructure by transmission electron microscopy indicates high chemical inhomogeneities due to phase coexistence between rich palladium regions (with FCC structure) and rich iron regions. The latter present a combination of BCC and amorphous phases. The average chemical composition of the nanowires can be better adjusted by using a low frequency square wave voltage excitation (alternating rich Pd and rich Fe regions). However, independently of the growth process, the nanowires morphology collapses after thermal annealing. This could be ascribed to fragile grain boundaries due to the presence of amorphous hydroxides and chemical impurities produced during the electrochemical process. - Highlights: • Synthesis of Fe−Pd nanowires by electrodeposition is reported. • Structural characterization of the nanowires by transmission electron microscopy. • The synthesis of nanowires with austenitic phase is limited by fragile grain boundaries.

  16. Atomistic theory of excitonic fine structure in InAs/InP nanowire quantum dot molecules

    Świderski, M.; Zieliński, M.

    2017-03-01

    Nanowire quantum dots have peculiar electronic and optical properties. In this work we use atomistic tight binding to study excitonic spectra of artificial molecules formed by a double nanowire quantum dot. We demonstrate a key role of atomistic symmetry and nanowire substrate orientation rather than cylindrical shape symmetry of a nanowire and a molecule. In particular for [001 ] nanowire orientation we observe a nonvanishing bright exciton splitting for a quasimolecule formed by two cylindrical quantum dots of different heights. This effect is due to interdot coupling that effectively reduces the overall symmetry, whereas single uncoupled [001 ] quantum dots have zero fine structure splitting. We found that the same double quantum dot system grown on [111 ] nanowire reveals no excitonic fine structure for all considered quantum dot distances and individual quantum dot heights. Further we demonstrate a pronounced, by several orders of magnitude, increase of the dark exciton optical activity in a quantum dot molecule as compared to a single quantum dot. For [111 ] systems we also show spontaneous localization of single particle states in one of nominally identical quantum dots forming a molecule, which is mediated by strain and origins from the lack of the vertical inversion symmetry in [111 ] nanostructures of overall C3 v symmetry. Finally, we study lowering of symmetry due to alloy randomness that triggers nonzero excitonic fine structure and the dark exciton optical activity in realistic nanowire quantum dot molecules of intermixed composition.

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

    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.

  18. Functional zinc oxide nanostructures for electronic and energy applications

    Prasad, Abhishek

    ZnO has proven to be a multifunctional material with important nanotechnological applications. ZnO nanostructures can be grown in various forms such as nanowires, nanorods, nanobelts, nanocombs etc. In this work, ZnO nanostructures are grown in a double quartz tube configuration thermal Chemical Vapor Deposition (CVD) system. We focus on functionalized ZnO Nanostructures by controlling their structures and tuning their properties for various applications. The following topics have been investigated: (1) We have fabricated various ZnO nanostructures using a thermal CVD technique. The growth parameters were optimized and studied for different nanostructures. (2) We have studied the application of ZnO nanowires (ZnONWs) for field effect transistors (FETs). Unintentional n-type conductivity was observed in our FETs based on as-grown ZnO NWs. We have then shown for the first time that controlled incorporation of hydrogen into ZnO NWs can introduce p-type characters to the nanowires. We further found that the n-type behaviors remained, leading to the ambipolar behaviors of hydrogen incorporated ZnO NWs. Importantly, the detected p- and n- type behaviors are stable for longer than two years when devices were kept in ambient conditions. All these can be explained by an ab initio model of Zn vacancy-Hydrogen complexes, which can serve as the donor, acceptors, or green photoluminescence quencher, depend on the number of hydrogen atoms involved. (3) Next ZnONWs were tested for electron field emission. We focus on reducing the threshold field (Eth) of field emission from non-aligned ZnO NWs. As encouraged by our results on enhancing the conductivity of ZnO NWs by hydrogen annealing described in Chapter 3, we have studied the effect of hydrogen annealing for improving field emission behavior of our ZnO NWs. We found that optimally annealed ZnO NWs offered much lower threshold electric field and improved emission stability. We also studied field emission from ZnO NWs at moderate

  19. Structurally controlled deposition of silicon onto nanowires

    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.

  20. Shape Engineering Driven by Selective Growth of SnO2 on Doped Ga2O3 Nanowires.

    Alonso-Orts, Manuel; Sánchez, Ana M; Hindmarsh, Steven A; López, Iñaki; Nogales, Emilio; Piqueras, Javier; Méndez, Bianchi

    2017-01-11

    Tailoring the shape of complex nanostructures requires control of the growth process. In this work, we report on the selective growth of nanostructured tin oxide on gallium oxide nanowires leading to the formation of SnO 2 /Ga 2 O 3 complex nanostructures. Ga 2 O 3 nanowires decorated with either crossing SnO 2 nanowires or SnO 2 particles have been obtained in a single step treatment by thermal evaporation. The reason for this dual behavior is related to the growth direction of trunk Ga 2 O 3 nanowires. Ga 2 O 3 nanowires grown along the [001] direction favor the formation of crossing SnO 2 nanowires. Alternatively, SnO 2 forms rhombohedral particles on [110] Ga 2 O 3 nanowires leading to skewer-like structures. These complex oxide structures were grown by a catalyst-free vapor-solid process. When pure Ga and tin oxide were used as source materials and compacted powders of Ga 2 O 3 acted as substrates, [110] Ga 2 O 3 nanowires grow preferentially. High-resolution transmission electron microscopy analysis reveals epitaxial relationship lattice matching between the Ga 2 O 3 axis and SnO 2 particles, forming skewer-like structures. The addition of chromium oxide to the source materials modifies the growth direction of the trunk Ga 2 O 3 nanowires, growing along the [001], with crossing SnO 2 wires. The SnO 2 /Ga 2 O 3 junctions does not meet the lattice matching condition, forming a grain boundary. The electronic and optical properties have been studied by XPS and CL with high spatial resolution, enabling us to get both local chemical and electronic information on the surface in both type of structures. The results will allow tuning optical and electronic properties of oxide complex nanostructures locally as a function of the orientation. In particular, we report a dependence of the visible CL emission of SnO 2 on its particular shape. Orange emission dominates in SnO 2 /Ga 2 O 3 crossing wires while green-blue emission is observed in SnO 2 particles attached to Ga 2

  1. Silicon Nanowire Field-effect Chemical Sensor

    Chen, S.

    2011-01-01

    This thesis describes the work that has been done on the project “Design and optimization of silicon nanowire for chemical sensing‿, including Si-NW fabrication, electrical/electrochemical modeling, the application as ISFET, and the build-up of Si- NW/LOC system for automatic sample delivery. A

  2. A simple method to fabricate an NIR detector by PbTe nanowires in a large scale

    Baghchesara, Mohammad Amin; Yousefi, Ramin; Cheraghizade, Mohsen; Jamali-Sheini, Farid; Saáedi, Abdolhossein; Mahmmoudian, M.R.

    2016-01-01

    Highlights: • PbTe nanowires were grown by tellurization of the Pb sheets for the first time. • It was observed a band gap value for the PbTe nanostructures in the NIR region. • NIR detector was fabricated in a large scale using a simple method. • Effect of Te concentration on morphology of PbTe nanostructures was investigated. - Abstract: A simple method was used to fabricate a near-infrared (NIR) detector using PbTe nanostructures. Samples were synthesized by tellurization of lead sheets in a tube furnace. PbTe nanostructures with wires and flakes shapes were grown on the lead sheets that were placed at 300 and 330 °C, respectively, while, PbTe nanoporous were grown at 360 and 390 °C. X-ray diffraction patterns and X-ray photoelectron spectra results indicated that, the PbTe phase was formed in all samples. UV–vis diffuse reflectance spectra measurements showed a band gap for the PbTe nanostructures in the near-infrared region of the electromagnetic spectrum. Actually, the results indicated that, the band gap values of the PbTe nanowires and nanoporous were 1.54 eV and 1.61 eV, respectively. Finally, the PbTe nanostructures were used as a simple photoresponse device under a red light source. The photoresponse results revealed, PbTe nanowires are promising for photoelectrical applications in the NIR region.

  3. Study of resonant processes in plasmonic nanostructures for sensor applications (Conference Presentation)

    Pirunčík, Jiří; Kwiecien, Pavel; Fiala, Jan; Richter, Ivan

    2017-05-01

    This contribution is focused on the numerical studies of resonant processes in individual plasmonic nanostructures, with the attention particularly given to rectangular nanoparticles and concominant localized surface plasmon resonance processes. Relevant models for the description and anylysis of localized surface plasmon resonance are introduced, in particular: quasistatic approximation, Mie theory and in particular, a generalized (quasi)analytical approach for treating rectangularly shaped nanostructures. The parameters influencing resonant behavior of nanoparticles are analyzed with special interest in morphology and sensor applications. Results acquired with Lumerical FDTD Solutions software, using finite-difference time-domain simulation method, are shown and discussed. Simulations were mostly performed for selected nanostructures composed of finite rectangular nanowires with square cross-sections. Systematic analysis is made for single nanowires with varying length, parallel couple of nanowires with varying gap (cut -wires) and selected dolmen structures with varying gap between one nanowire transversely located with respect to parallel couple of nanowires (in both in-plane and -out-of-plane arrangements). The dependence of resonant peaks of cross-section spectral behavior (absorption, scattering, extinction) and their tunability via suitable structuring and morphology changes are primarily researched. These studies are then followed with an analysis of the effect of periodic arrangements. The results can be usable with respect to possible sensor applications.

  4. Global optimization of silicon nanowires for efficient parametric processes

    Vukovic, Dragana; Xu, Jing; Mørk, Jesper

    2013-01-01

    We present a global optimization of silicon nanowires for parametric single-pump mixing. For the first time, the effect of surface roughness-induced loss is included in the analysis, significantly influencing the optimum waveguide dimensions.......We present a global optimization of silicon nanowires for parametric single-pump mixing. For the first time, the effect of surface roughness-induced loss is included in the analysis, significantly influencing the optimum waveguide dimensions....

  5. Photonic Nanostructures Design and Optimization for Solar Cell Application

    Qian Liu

    2015-08-01

    Full Text Available In this paper, a semiconducting photonic nanostructure capable of wide range absorption and tunable optical resonance has been designed with a proposed theoretical optimization model. The design consists of ZnO/CdS core-shell nanowire arrays as well as multilayer thin films that act to absorb incident electromagnetic (EM waves over a broad frequency range. Theoretical, as well as numerical, studies of the nanostructure inside a solar cell plate have been conducted in order to validate the proposed microstructural design. Excellent energy absorption rates of EM waves have been achieved in the high frequency range by using the optical resonance of the nanowire array. By combining multilayer thin film with the core-shell nanowire in the unit cell of a photonic solar cell, a broadband high absorption has been achieved. Moreover, the geometry of the proposed photonic nanostructure is obtained through the implementation of a genetic algorithm. This avoids local minima and an optimized absorption rate of ~90% over the frequency range of 300 to 750 THz has been obtained in the solar cell.

  6. Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting.

    Varadhan, Purushothaman; Fu, Hui-Chun; Priante, Davide; Retamal, Jose Ramon Duran; Zhao, Chao; Ebaid, Mohamed; Ng, Tien Khee; Ajia, Idirs; Mitra, Somak; Roqan, Iman S; Ooi, Boon S; He, Jr-Hau

    2017-03-08

    Hydrogen production via photoelectrochemical water-splitting is a key source of clean and sustainable energy. The use of one-dimensional nanostructures as photoelectrodes is desirable for photoelectrochemical water-splitting applications due to the ultralarge surface areas, lateral carrier extraction schemes, and superior light-harvesting capabilities. However, the unavoidable surface states of nanostructured materials create additional charge carrier trapping centers and energy barriers at the semiconductor-electrolyte interface, which severely reduce the solar-to-hydrogen conversion efficiency. In this work, we address the issue of surface states in GaN nanowire photoelectrodes by employing a simple and low-cost surface treatment method, which utilizes an organic thiol compound (i.e., 1,2-ethanedithiol). The surface-treated photocathode showed an enhanced photocurrent density of -31 mA/cm 2 at -0.2 V versus RHE with an incident photon-to-current conversion efficiency of 18.3%, whereas untreated nanowires yielded only 8.1% efficiency. Furthermore, the surface passivation provides enhanced photoelectrochemical stability as surface-treated nanowires retained ∼80% of their initial photocurrent value and produced 8000 μmol of gas molecules over 55 h at acidic conditions (pH ∼ 0), whereas the untreated nanowires demonstrated only passivation of nanostructured photoelectrodes for photoelectrochemical applications.

  7. Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting

    Varadhan, Purushothaman; Fu, Hui-chun; Priante, Davide; Duran Retamal, Jose Ramon; Zhao, Chao; Ebaid, Mohamed; Ng, Tien Khee; Ajia, Idris A.; Mitra, Somak; Roqan, Iman S.; Ooi, Boon S.; He, Jr-Hau

    2017-01-01

    Hydrogen production via photoelectrochemical water-splitting is a key source of clean and sustainable energy. The use of one-dimensional nanostructures as photoelectrodes is desirable for photoelectrochemical water-splitting applications due to the ultralarge surface areas, lateral carrier extraction schemes, and superior light-harvesting capabilities. However, the unavoidable surface states of nanostructured materials create additional charge carrier trapping centers and energy barriers at the semiconductor-electrolyte interface, which severely reduce the solar-to-hydrogen conversion efficiency. In this work, we address the issue of surface states in GaN nanowire photoelectrodes by employing a simple and low-cost surface treatment method, which utilizes an organic thiol compound (i.e., 1,2-ethanedithiol). The surface-treated photocathode showed an enhanced photocurrent density of −31 mA/cm at −0.2 V versus RHE with an incident photon-to-current conversion efficiency of 18.3%, whereas untreated nanowires yielded only 8.1% efficiency. Furthermore, the surface passivation provides enhanced photoelectrochemical stability as surface-treated nanowires retained ∼80% of their initial photocurrent value and produced 8000 μmol of gas molecules over 55 h at acidic conditions (pH ∼ 0), whereas the untreated nanowires demonstrated only <4 h of photoelectrochemical stability. These findings shed new light on the importance of surface passivation of nanostructured photoelectrodes for photoelectrochemical applications.

  8. Light-induced antifungal activity of TiO{sub 2} nanoparticles/ZnO nanowires

    Haghighi, N. [Nano-Physics Research Lab., Department of Physics, University of Tehran, Tehran (Iran, Islamic Republic of); Abdi, Y., E-mail: y.abdi@ut.ac.ir [Nano-Physics Research Lab., Department of Physics, University of Tehran, Tehran (Iran, Islamic Republic of); Haghighi, F. [Department of Medical Mycology, School of Medical sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2011-09-15

    Antifungal activity of TiO{sub 2}/ZnO nanostructures under visible light irradiation was investigated. A simple chemical method was used to synthesize ZnO nanowires. Zinc acetate dihydrate, Polyvinyl Pyrrolidone and deionized water were used as precursor, capping and solvent, respectively. TiO{sub 2} nanoparticles were deposited on ZnO nanowires using an atmospheric pressure chemical vapor deposition system. X-ray diffraction pattern of TiO{sub 2}/ZnO nano-composite has represented the diffraction peaks relating to the crystal planes of the TiO{sub 2} (anatase and rutile) and ZnO. TiO{sub 2}/ZnO nanostructure antifungal effect on Candida albicans biofilms was studied and compared with the activity of TiO{sub 2} nanoparticles and ZnO nanowires. The high efficiency photocatalytic activity of TiO{sub 2} nanoparticles leads to increased antifungal activity of ZnO nanowires. Scanning electron microscope was utilized to study the morphology of the as prepared nanostructures and the degradation of the yeast.

  9. Light-induced antifungal activity of TiO2 nanoparticles/ZnO nanowires

    Haghighi, N.; Abdi, Y.; Haghighi, F.

    2011-01-01

    Antifungal activity of TiO 2 /ZnO nanostructures under visible light irradiation was investigated. A simple chemical method was used to synthesize ZnO nanowires. Zinc acetate dihydrate, Polyvinyl Pyrrolidone and deionized water were used as precursor, capping and solvent, respectively. TiO 2 nanoparticles were deposited on ZnO nanowires using an atmospheric pressure chemical vapor deposition system. X-ray diffraction pattern of TiO 2 /ZnO nano-composite has represented the diffraction peaks relating to the crystal planes of the TiO 2 (anatase and rutile) and ZnO. TiO 2 /ZnO nanostructure antifungal effect on Candida albicans biofilms was studied and compared with the activity of TiO 2 nanoparticles and ZnO nanowires. The high efficiency photocatalytic activity of TiO 2 nanoparticles leads to increased antifungal activity of ZnO nanowires. Scanning electron microscope was utilized to study the morphology of the as prepared nanostructures and the degradation of the yeast.

  10. Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting

    Varadhan, Purushothaman

    2017-02-08

    Hydrogen production via photoelectrochemical water-splitting is a key source of clean and sustainable energy. The use of one-dimensional nanostructures as photoelectrodes is desirable for photoelectrochemical water-splitting applications due to the ultralarge surface areas, lateral carrier extraction schemes, and superior light-harvesting capabilities. However, the unavoidable surface states of nanostructured materials create additional charge carrier trapping centers and energy barriers at the semiconductor-electrolyte interface, which severely reduce the solar-to-hydrogen conversion efficiency. In this work, we address the issue of surface states in GaN nanowire photoelectrodes by employing a simple and low-cost surface treatment method, which utilizes an organic thiol compound (i.e., 1,2-ethanedithiol). The surface-treated photocathode showed an enhanced photocurrent density of −31 mA/cm at −0.2 V versus RHE with an incident photon-to-current conversion efficiency of 18.3%, whereas untreated nanowires yielded only 8.1% efficiency. Furthermore, the surface passivation provides enhanced photoelectrochemical stability as surface-treated nanowires retained ∼80% of their initial photocurrent value and produced 8000 μmol of gas molecules over 55 h at acidic conditions (pH ∼ 0), whereas the untreated nanowires demonstrated only <4 h of photoelectrochemical stability. These findings shed new light on the importance of surface passivation of nanostructured photoelectrodes for photoelectrochemical applications.

  11. Structural characterization of one-dimensional ZnO-based nanostructures grown by MOCVD

    Sallet, Vincent; Falyouni, Farid; Marzouki, Ali; Haneche, Nadia; Sartel, Corinne; Lusson, Alain; Galtier, Pierre [Groupe d' Etude de la Matiere Condensee (GEMAC), CNRS-Universite de Versailles St-Quentin, Meudon (France); Agouram, Said [SCSIE, Universitat de Valencia, Burjassot (Spain); Enouz-Vedrenne, Shaima [Thales Research and Technology France, Palaiseau (France); Munoz-Sanjose, Vicente [Departamento de Fisica Aplicada y Electromagnetismo, Universitat de Valencia, Burjassot (Spain)

    2010-07-15

    Various one-dimensional (1D) ZnO-based nanostructures, including ZnO nano-wires (NWs) grown using vapour-liquid-solid (VLS) process, ZnO/ZnSe core/shell, nitrogen-doped ZnO and ZnMgO NWs were grown by metalorganic chemical vapour deposition (MOCVD). Transmission electron microscopy (TEM) analysis is presented. For all the samples, a high crystalline quality is observed. Some features are emphasized such as the gold contamination of ZnO wires grown under the metal droplets in the VLS process. It is concluded that MOCVD is a suitable technique for the realization of original ZnO nanodevices. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. Three-Dimensional Superhydrophobic Nanowire Networks for Enhancing Condensation Heat Transfer

    Yang, Ronggui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wen, Rongfu [University of Colorado; Xu, Shanshan [University of Colorado; Ma, Xuehu [Dalian University of Technology; Lee, Yung-Cheng [University of Colorado

    2017-12-18

    Spontaneous droplet jumping on nanostructured surfaces can potentially enhance condensation heat transfer by accelerating droplet removal. However, uncontrolled nucleation in the micro-defects of nanostructured superhydrophobic surfaces could lead to the formation of large pinned droplets, which greatly degrades the performance. Here, we experimentally demonstrate for the first time stable and efficient jumping droplet condensation on a superhydrophobic surface with three-dimensional (3D) copper nanowire networks. Due to the formation of interconnections among nanowires, the micro-defects are eliminated while the spacing between nanowires is reduced, which results in the formation of highly mobile droplets. By preventing flooding on 3D nanowire networks, we experimentally demonstrate a 100% higher heat flux compared with that on the state-of-the-art hydrophobic surface over a wide range of subcooling (up to 28 K). The remarkable water repellency of 3D nanowire networks can be applied to a broad range of water-harvesting and phase-change heat transfer applications.

  13. Hydrothermal growth of titania nanowires for SAW device sensing area

    Zakaria Mohd Rosydi

    2017-01-01

    Full Text Available Synthesis of titania or titanium dioxide (TiO2 is attracted to energy and environmental applications. Here, the growth of nanostructure TiO2 nanowires on Si (100 substrates by using the two-step method. Different seed layers of TiO2 were deposited by spin coating and annealing, followed by the growth of TiO2 nanowires by using the hydrothermal method. The sol-gel technique was used in preparing the TiO2 solution for the thin film deposition purpose. Acetic acid, hydrochloric acid and tris (2-aminoethyl amine were used as a stabilizer to synthesize three different TiO2 seed layers. The aim of this study was to understand the role of polycrystalline size on thin film towards the diameter of nanowires grown as a sensing area in Surface Acoustic Wave (SAW Biosensor. The morphology and structure of the thin film and TiO2 nanowires were characterized using X-Ray diffraction (XRD, scanning electron microscope (SEM, field emission scanning electron microscope (FESEM and atomic force microscopy (AFM.

  14. Facile and rapid synthesis of nickel nanowires and their magnetic properties

    Tang Shaochun; Zheng Zhou; Vongehr, Sascha; Meng Xiangkang

    2011-01-01

    The present work reports a facile and rapid microwave-assisted route to synthesize nickel nanowires with a necklace-like morphology and lengths up to several hundreds of microns. The wires consist of many crystallites with an average size of 25 ± 2 nm. The synthesis does not use templates or magnetic fields and needs only 6 min, which is more than 480 times faster than that needed for Ni wires prepared at 180 °C using conventional heating. Nickel nanostructures with various morphologies including spheres, chains and irregular particles with porous surfaces can also be obtained by adjusting reaction parameters. Polyvinylpyrrolidone (PVP) is found to be vital for the formation of the one-dimensional chains and a high concentration of PVP smoothes their surfaces to result in the appearance of wires. This rapid one-pot procedure combines the formation of nanoparticles, their oriented assembly into chains, and the subsequent shaping of wires. The Ni nanostructures show variable magnetic properties. The prepared nickel wires have a high mechanical stability and exhibit much higher coercivity than bulk nickel, Ni nanoparticles and their aggregations, which promise potential applications in micromechanical sensors, memory devices and other fields.

  15. Controlled synthesis of uniform ultrafine CuO nanowires as anode material for lithium-ion batteries

    Wang Fei; Tao Weizhe; Zhao Mingshu; Xu Minwei; Yang Shengchun; Sun Zhanbo; Wang Liqun; Song Xiaoping

    2011-01-01

    Highlights: → The ultrafine CuO nanowires were controlled synthesized by a simple solution route. → CuO nanowires exhibit high capacity, superior cyclability and improved rate capability. → Voltage-capacity curves show larger extra reversible reactions at low potentials in CuO nanowires. → CV curves show lower over-potential in CuO nanowires. - Abstract: A simple solution route is used to synthesize ultrafine Cu(OH) 2 nanowires by restraining the morphology transformation of early formed 1D nanostructure. The obtained ultrafine nanowires can be well preserved at a low temperature structure transformation in solid state. As anode material for lithium-ion batteries, the ultrafine CuO nanowires exhibit high reversible capacity, superior cycling performance and improved rate capability. The improved electrochemical properties of CuO nanowires are ascribed to their ultrafine size which lead to the reduced over-potential, extra reversible reactions at low potentials and improved interface performance between the electrode and electrolyte.

  16. Simulataneous Formation of InGaN Nanostructures with Varying Shapes for White Light Source Applications

    Gasim, Anwar A.; Bhattacharya, Pallab K.; Cha, Dong Kyu; Ng, Tien Khee; Ooi, Boon S.

    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.

  17. Spark-plasma-sintering magnetic field assisted compaction of Co{sub 80}Ni{sub 20} nanowires for anisotropic ferromagnetic bulk materials

    Ouar, Nassima; Schoenstein, Frédéric; Mercone, Silvana; Farhat, Samir; Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux, CNRS, LSPM—UPR 3407, Université Paris 13, Sorbonne-Paris-Cité, 99 Avenue J.-B. Clément, 93430 Villetaneuse (France); Villeroy, Benjamin [Institut de Chimie et des Matériaux Paris Est, CNRS, ICMPE—UMR 7182, Equipe de Chimie Métallurgique des Terres Rares, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Leridon, Brigitte [Laboratoire de Physique et d’Étude des Matériaux, LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5 (France)

    2013-10-28

    We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing the synthesis of several grams per batch of nanopowders via a polyol soft chemistry route. The feasibility of the scale-up has been successfully demonstrated for Co{sub 80}Ni{sub 20} nanowires and a massic yield of ∼97% was obtained. The thus obtained nanowires show an average diameter of ∼6 nm and a length of ∼270 nm. A new bottom-up strategy allowed us to compact the powder into a bulk nanostructured system. We used a spark-plasma-sintering technique under uniaxial compression and low temperature assisted by a permanent magnetic field of 1 T. A macroscopic pellet of partially aligned nanowire arrays has been easily obtained. This showed optimized coercive properties along the direction of the magnetic field applied during compaction (i.e., the nanowires' direction)

  18. Vicinal surfaces for functional nanostructures.

    Tegenkamp, Christoph

    2009-01-07

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF(2), MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior.

  19. Vicinal surfaces for functional nanostructures

    Tegenkamp, Christoph [Institut fuer Festkoerperphysik, Gottfried Wilhelm Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)], E-mail: tegenkamp@fkp.uni-hannover.de

    2009-01-07

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF{sub 2}, MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior. (topical review)

  20. Vicinal surfaces for functional nanostructures

    Tegenkamp, Christoph

    2009-01-01

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF 2 , MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior. (topical review)

  1. Protein Biosensors Based on Polymer Nanowires, Carbon Nanotubes and Zinc Oxide Nanorods

    Taeksoo Ji

    2011-05-01

    Full Text Available The development of biosensors using electrochemical methods is a promising application in the field of biotechnology. High sensitivity sensors for the bio-detection of proteins have been developed using several kinds of nanomaterials. The performance of the sensors depends on the type of nanostructures with which the biomaterials interact. One dimensional (1-D structures such as nanowires, nanotubes and nanorods are proven to have high potential for bio-applications. In this paper we review these three different kinds of nanostructures that have attracted much attention at recent times with their great performance as biosensors. Materials such as polymers, carbon and zinc oxide have been widely used for the fabrication of nanostructures because of their enhanced performance in terms of sensitivity, biocompatibility, and ease of preparation. Thus we consider polymer nanowires, carbon nanotubes and zinc oxide nanorods for discussion in this paper. We consider three stages in the development of biosensors: (a fabrication of biomaterials into nanostructures, (b alignment of the nanostructures and (c immobilization of proteins. Two different methods by which the biosensors can be developed at each stage for all the three nanostructures are examined. Finally, we conclude by mentioning some of the major challenges faced by many researchers who seek to fabricate biosensors for real time applications.

  2. Hierarchical oxide-based composite nanostructures for energy, environmental, and sensing applications

    Gao, Pu-Xian; Shimpi, Paresh; Cai, Wenjie; Gao, Haiyong; Jian, Dunliang; Wrobel, Gregory

    2011-02-01

    Self-assembled composite nanostructures integrate various basic nano-elements such as nanoparticles, nanofilms and nanowires toward realizing multifunctional characteristics, which promises an important route with potentially high reward for the fast evolving nanoscience and nanotechnology. A broad array of hierarchical metal oxide based nanostructures have been designed and fabricated in our research group, involving semiconductor metal oxides, ternary functional oxides such as perovskites and spinels and quaternary dielectric hydroxyl metal oxides with diverse applications in efficient energy harvesting/saving/utilization, environmental protection/control, chemical sensing and thus impacting major grand challenges in the area of materials and nanotechnology. Two of our latest research activities have been highlighted specifically in semiconductor oxide alloy nanowires and metal oxide/perovskite composite nanowires, which could impact the application sectors in ultraviolet/blue lighting, visible solar absorption, vehicle and industry emission control, chemical sensing and control for vehicle combustors and power plants.

  3. Structural origination of charge transfer complex nanostructures: Excellent candidate for field emission

    Pal, Shreyasi; Chattopadhyay, Kalyan Kumar

    2016-01-01

    Worldwide strategies for amalgamating rationally controlled one-dimensional organic nanowires are of fundamental importance for their applications in flexible, cheaper and lighter electronics. In this work we have fabricated large-area, ordered CuTCNQ (copper-7,7,8,8-tetracyanoquinodimethane) nano architecture arrays over flexible conducting substrate and discussed the rational growth and integration of nanostructures. Here we adopted the organic solid phase reaction (VLS) technique for the growth of organic hierarchies and investigated how field emission properties changes by tuning the nanostructures morphology i.e., by varying length, diameter, alignment and orientation over flexible substrate. The CuTCNQ nanowires with optimized geometry exhibit excellent high field emission performance with low turn-on and threshold field values. The result strongly indicate that CuTCNQ nanowires on flexible carbon cloth substrate are promising candidates for constructing cold cathode based emission display devices, vacuum nanoelectronics, and etc.

  4. Structural origination of charge transfer complex nanostructures: Excellent candidate for field emission

    Pal, Shreyasi; Chattopadhyay, Kalyan Kumar [Thin Films and Nanoscience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India)

    2016-05-23

    Worldwide strategies for amalgamating rationally controlled one-dimensional organic nanowires are of fundamental importance for their applications in flexible, cheaper and lighter electronics. In this work we have fabricated large-area, ordered CuTCNQ (copper-7,7,8,8-tetracyanoquinodimethane) nano architecture arrays over flexible conducting substrate and discussed the rational growth and integration of nanostructures. Here we adopted the organic solid phase reaction (VLS) technique for the growth of organic hierarchies and investigated how field emission properties changes by tuning the nanostructures morphology i.e., by varying length, diameter, alignment and orientation over flexible substrate. The CuTCNQ nanowires with optimized geometry exhibit excellent high field emission performance with low turn-on and threshold field values. The result strongly indicate that CuTCNQ nanowires on flexible carbon cloth substrate are promising candidates for constructing cold cathode based emission display devices, vacuum nanoelectronics, and etc.

  5. Ultra-thin graphene edges at the nanowire tips: a cascade cold cathode with two-stage field amplification

    Maiti, Uday N; Majumder, Tapas Pal; Maiti, Soumen; Chattopadhyay, Kalyan K

    2011-01-01

    A multistage field emitter based on graphene-linked ZnO nanowire array is realized by means of spin-coating a graphene dispersion (reduced graphene oxide) over a nanostructured platform followed by plasma modification. Spin-coating leads to interlinking of graphene sheets between the neighboring nanowires whereas plasma etching in the subsequent step generates numerous ultra-sharp graphene edges at the nanowire tips. The inherent tendency of graphene to lay flat over a plane substrate can easily be bypassed through the currently presented nanostructure platform based technique. The turn-on and threshold field significantly downshifted compared to the individual components in the cascade emitter. Through the facile electron transfer from nanowires to graphene due to band bending at the ZnO–graphene interface together with multistage geometrical field enhancement at both the nanowire and graphene edges remain behind this enriched field emission from the composite cold cathode. This strategy will open up a new direction to integrate the functionalities of both the graphene array and several other inorganic nanostructure array for practical electronic devices.

  6. Photoresponsive properties of ultrathin silicon nanowires

    Tran, Duy P.; Macdonald, Thomas J.; Nann, Thomas; Thierry, Benjamin; Wolfrum, Bernhard; Stockmann, Regina; Offenhäusser, Andreas

    2014-01-01

    Functional silicon nanowires (SiNWs) are promising building blocks in the design of highly sensitive photodetectors and bio-chemical sensors. We systematically investigate the photoresponse properties of ultrathin SiNWs (20 nm) fabricated using a size-reduction method based on e-beam lithography and tetramethylammonium hydroxide wet-etching. The high-quality SiNWs were able to detect light from the UV to the visible range with excellent sensitivity (∼1 pW/array), good time response, and high photoresponsivity (R ∼ 2.5 × 10 4  A/W). Improvement of the ultrathin SiNWs' photoresponse has been observed in comparison to 40 nm counter-part nanowires. These properties are attributable to the predominance surface-effect due to the high surface-to-volume ratio of ultrathin SiNWs. Long-term measurements at different temperatures in both the forward and reverse bias directions demonstrated the stability and reliability of the fabricated device. By sensitizing the fabricated SiNW arrays with cadmium telluride quantum dots (QDs), hybrid QD SiNW devices displayed an improvement in photocurrent response under UV light, while preserving their performance in the visible light range. The fast, stable, and high photoresponse of these hybrid nanostructures is promising towards the development of optoelectronic and photovoltaic devices

  7. Photoresponsive properties of ultrathin silicon nanowires

    Tran, Duy P.; Macdonald, Thomas J.; Nann, Thomas; Thierry, Benjamin, E-mail: a.offenhaeusser@fz-juelich.de, E-mail: benjamin.thierry@unisa.edu.au [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, MM Bldg., Mawson Lakes Blvd., Mawson Lakes, South Australia 5095 (Australia); Wolfrum, Bernhard; Stockmann, Regina; Offenhäusser, Andreas, E-mail: a.offenhaeusser@fz-juelich.de, E-mail: benjamin.thierry@unisa.edu.au [Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 2.4v Bldg., Wilhelm-Johnen St., Jülich 52428 (Germany)

    2014-12-08

    Functional silicon nanowires (SiNWs) are promising building blocks in the design of highly sensitive photodetectors and bio-chemical sensors. We systematically investigate the photoresponse properties of ultrathin SiNWs (20 nm) fabricated using a size-reduction method based on e-beam lithography and tetramethylammonium hydroxide wet-etching. The high-quality SiNWs were able to detect light from the UV to the visible range with excellent sensitivity (∼1 pW/array), good time response, and high photoresponsivity (R ∼ 2.5 × 10{sup 4 }A/W). Improvement of the ultrathin SiNWs' photoresponse has been observed in comparison to 40 nm counter-part nanowires. These properties are attributable to the predominance surface-effect due to the high surface-to-volume ratio of ultrathin SiNWs. Long-term measurements at different temperatures in both the forward and reverse bias directions demonstrated the stability and reliability of the fabricated device. By sensitizing the fabricated SiNW arrays with cadmium telluride quantum dots (QDs), hybrid QD SiNW devices displayed an improvement in photocurrent response under UV light, while preserving their performance in the visible light range. The fast, stable, and high photoresponse of these hybrid nanostructures is promising towards the development of optoelectronic and photovoltaic devices.

  8. Preparation and characterization of titania based nanowires

    Stengl, Vaclav; Bakardjieva, Snejana; Murafa, Natalie; Vecernikova, Eva; Subrt, Jan; Balek, Vladimir

    2007-01-01

    A new method for preparation of titania nanowires with diameter around 10 nm and length up to 2-3 μm is described. The precursor was prepared from sodium titanate by adding ethylene glycole (EG) and heating at temperature of 198 deg. C for 6 h under reflux. The sodium titanate glycolate formed by this way aggregated into 1D nanostructures and was subsequently transformed into titania glycolate during a chemical treatment with 98% sulfuric acid. Titania nanowires with variable amount of anatase and rutile were prepared by heating to temperatures in the range 350-1000 deg. C. The precursor as well as titania based samples were characterized by X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, High resolution transmission microscopy, Thermogravimetry, Differential thermal analysis, Evolved gas analysis and Emanation thermal analysis. The nitrogen adsorption/desorption was used for surface area and porosity determination. The photoactivity of the prepared titania samples was assessed by the photocatalytic decomposition of 4-chlorophenol in an aqueous slurry under UV irradiation of 365 nm wavelength

  9. Anodized ZnO nanostructures for photoelectrochemical water splitting

    Huang, Mao-Chia [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Wang, TsingHai [Department of Biomedical Engineering and Environment Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Wu, Bin-Jui [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Lin, Jing-Chie, E-mail: jclin4046@gmail.com [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Wu, Ching-Chen [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China)

    2016-01-01

    Highlights: • ZnO nanostructures were synthesized by electrochemical anodic process. • The parameter of ZnO nanostructure was anodic potential. • The model of growth of ZnO nanostructure was investigated. - Abstract: Zinc oxide (ZnO) nanostructures were fabricated on the polished zinc foil by anodic deposition in an alkaline solution containing 1.0 M NaOH and 0.25 M Zn(NO{sub 3}){sub 2}. Potentiostatic anodization was conducted at two potentials (−0.7 V in the passive region and −1.0 V in the active region vs. SCE) which are higher than the open circuit potential (−1.03 V vs. SCE) and as-obtained ZnO nanostrcutures were investigated focusing on their structural, optical, electrical and photoelectrochemical (PEC) characteristics. All samples were confirmed ZnO by X-ray photoelectron spectroscopy and Raman spectra. Observations in the SEM images clearly showed that ZnO nanostructures prepared at −0.7 V vs. SCE were composed of nanowires at while those obtained at −1.0 V vs. SCE possessed nanosheets morphology. Result from transmission electron microscope and X-ray diffraction patterns suggested that the ZnO nanowires belonged to single crystalline with a preferred orientation of (0 0 2) whereas the ZnO nanosheets were polycrystalline. Following PEC experiments indicated that ZnO nanowires had higher photocurrent density of 0.32 mA/cm{sup 2} at 0.5 V vs. SCE under 100 mW/cm{sup 2} illumination. This value was about 1.9 times higher than that of ZnO nanosheets. Observed higher photocurrent was likely due to the single crystalline, preferred (0 0 2) orientation, higher carrier concentration and lower charge transfer resistance.

  10. Printing nanotube/nanowire for flexible microsystems

    Tortorich, Ryan P.; Choi, Jin-Woo

    2014-04-01

    Printing has become an emerging manufacturing technology for mechanics, electronics, and consumer products. Additionally, both nanotubes and nanowires have recently been used as materials for sensors and electrodes due to their unique electrical and mechanical properties. Printed electrodes and conductive traces particularly offer versatility of fabricating low-cost, disposable, and flexible electrical devices and microsystems. While various printing methods such as screen printing have been conventional methods for printing conductive traces and electrodes, inkjet printing has recently attracted great attention due to its unique advantages including no template requirement, rapid printing at low cost, on-demand printing capability, and precise control of the printed material. Computer generated conductive traces or electrode patterns can simply be printed on a thin film substrate with proper conductive ink consisting of nanotubes or nanowires. However, in order to develop nanotube or nanowire ink, there are a few challenges that need to be addressed. The most difficult obstacle to overcome is that of nanotube/nanowire dispersion within a solution. Other challenges include adjusting surface tension and controlling viscosity of the ink as well as treating the surface of the printing substrate. In an attempt to pave the way for nanomaterial inkjet printing, we present a method for preparing carbon nanotube ink as well as its printing technique. A fully printed electrochemical sensor using inkjet-printed carbon nanotube electrodes is also demonstrated as an example of the possibilities for this technology.

  11. Laser-induced single point nanowelding of silver nanowires

    Dai, Shuowei; Li, Qiang; Liu, Guoping; Yang, Hangbo; Yang, Yuanqing; Zhao, Ding; Wang, Wei; Qiu, Min

    2016-01-01

    Nanowelding of nanomaterials opens up an emerging set of applications in transparent conductors, thin-film solar cells, nanocatalysis, cancer therapy, and nanoscale patterning. Single point nanowelding (SPNW) is highly demanded for building complex nanostructures. In this letter, the precise control of SPNW of silver nanowires is explored in depth, where the nanowelding is laser-induced through the plasmonic resonance enhanced photothermal effect. It is shown that the illumination position is a critical factor for the nanowelding process. As an example of performance enhancement, output at wire end can be increased by 65% after welding for a plasmonic nanocoupler. Thus, single point nanowelding technique shows great potentials for high-performance electronic and photonic devices based on nanowires, such as nanoelectronic circuits and plasmonic nanodevices.

  12. Laser-induced single point nanowelding of silver nanowires

    Dai, Shuowei; Li, Qiang, E-mail: qiangli@zju.edu.cn; Liu, Guoping; Yang, Hangbo; Yang, Yuanqing; Zhao, Ding; Wang, Wei; Qiu, Min, E-mail: minqiu@zju.edu.cn [State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-03-21

    Nanowelding of nanomaterials opens up an emerging set of applications in transparent conductors, thin-film solar cells, nanocatalysis, cancer therapy, and nanoscale patterning. Single point nanowelding (SPNW) is highly demanded for building complex nanostructures. In this letter, the precise control of SPNW of silver nanowires is explored in depth, where the nanowelding is laser-induced through the plasmonic resonance enhanced photothermal effect. It is shown that the illumination position is a critical factor for the nanowelding process. As an example of performance enhancement, output at wire end can be increased by 65% after welding for a plasmonic nanocoupler. Thus, single point nanowelding technique shows great potentials for high-performance electronic and photonic devices based on nanowires, such as nanoelectronic circuits and plasmonic nanodevices.

  13. Synthesis, microstructure, and physical properties of metallic barcode nanowires

    Park, Bum Chul; Kim, Young Keun

    2017-05-01

    With rapid progress in nanotechnology, nanostructured materials have come closer to our life. Single-component nanowires are actively investigated because of their novel properties, attributed to their nanoscale dimensions and adjustable aspect ratio, but their technical limitations cannot be resolved easily. Heterostructured nanomaterials gained attention as alternatives because they can improve the existing single-component structure or add new functions to it. Among them, barcode nanowires (BNWs), comprising at least two different functional segments, can perform multiple functions for use in biomedical sensors, information encoding and security, and catalysts. BNW applications require reliable response to the external field. Hence, researchers have been attempting to improve the reliability of synthesis and regulate the properties precisely. This article highlights the recent progress and prospects for the synthesis, properties, and applications of metallic BNWs with focus on the dependence of the magnetic, optical, and mechanical properties on material, composition, shape, and microstructure.

  14. Nanostructured sulfur cathodes

    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.

  15. Urea route to coat inorganic nanowires, carbon fibers and nanotubes by boron nitride

    Gomathi, A.; Ramya Harika, M.; Rao, C.N.R.

    2008-01-01

    A simple route involving urea as the nitrogen source has been employed to carry out boron nitride coating on carbon fibers, multi-walled carbon nanotubes and inorganic nanowires. The process involves heating the carbon fibers and nanotubes or inorganic nanowires in a mixture of H 3 BO 3 and urea, followed by a heat treatment at 1000 deg. C in a N 2 atmosphere. We have been able to characterize the BN coating by transmission electron microscopy as well as X-ray photoelectron spectroscopy. The urea decomposition route affords a simple method to coat boron nitride on one-dimensional nanostructures

  16. Microwave-controlled ultrafast synthesis of uniform silver nanocubes and nanowires

    Zhao, Tian; Fan, Jun-Bing; Cui, Jing; Liu, Jin-Hua; Xu, Xiao-Bo; Zhu, Ming-Qiang

    2011-01-01

    Synthesis of well-defined silver nanostructure in terms of size and shape has been strongly motivated by the requirements to their size- and shape-dependent optical properties which achieve their practical applications ranging from biosensing to catalysis and optics. In this Letter, an ultrafast synthetic process for the well-defined Ag nanocubes and nanowires have been developed, which simply involve the microwave-mediated polyol reduction of silver nitrate in ethylene glycol by adding different amount sodium sulfide (Na2S) into the solution. The possible growth and evolution process of the Ag nanocubes and nanowires involves the microwave ultrafast nucleation and growth followed by oxidative etching of Ag nanocrystals.

  17. Silicon nanowires used as the anode of a lithium-ion battery

    Prosini, Pier Paolo; Rufoloni, Alessandro; Rondino, Flaminia; Santoni, Antonino

    2014-01-01

    In this paper the synthesis and characterization of silicon nanowires to be used as the anode of a lithium-ion battery cell are reported. The nanowires were synthesized by CVD and characterized by SEM. The nanostructured material was used as an electrode in a lithium cell and its electrochemical properties were investigated by galvanostatic charge/discharge cycles at C/10 rate as a function of the cycle number and at various rates as a function of the charge current. The electrode was then coupled with a LiFePO 4 cathode to fabricate a lithium-ion battery cell and the cell performance evaluated by galvanostatic charge/discharge cycles

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

    Dadwal, U.; Singh, R. [Nanoscale Research Facility (NRF), Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016 (India); Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016 (India); Ranjan, Neha [Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia, New Delhi-110025 (India)

    2016-05-23

    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 AgNO{sub 3}. 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.

  19. Passivation of ZnO Nanowire Guests and 3D Inverse Opal Host Photoanodes for Dye-Sensitized Solar Cells

    Labouchere, Philippe; Chandiran, Aravind Kumar; Moehl, Thomas; Harms, Hauke; Chavhan, Sudam; Tena-Zaera, Ramon; Nazeeruddin, Mohammad Khaja; Graetzel, Michael; Tetreault, Nicolas

    2014-01-01

    A hierarchical host-guest nanostructured photoanode is reported for dye-sensitized solar cells. It is composed of ZnO nanowires grown in situ into the macropores of a 3D ZnO inverse opal structure, which acts both as a seed layer and as a conductive

  20. Influence of External Gaseous Environments on the Electrical Properties of ZnO Nanostructures Obtained by a Hydrothermal Method

    Marcin Procek

    2016-11-01

    Full Text Available This paper deals with experimental investigations of ZnO nanostructures, consisting of a mixture of nanoparticles and nanowires, obtained by the chemical (hydrothermal method. The influences of both oxidizing (NO2 and reducing gases (H2, NH3, as well as relative humidity (RH on the physical and chemical properties of ZnO nanostructures were tested. Carrier gas effect on the structure interaction with gases was also tested; experiments were conducted in air and nitrogen (N2 atmospheres. The effect of investigated gases on the resistance of the ZnO nanostructures was tested over a wide range of concentrations at room temperature (RT and at 200 °C. The impact of near- ultraviolet (UV excitation (λ = 390 nm at RT was also studied. These investigations indicated a high response of ZnO nanostructures to small concentrations of NO2. The structure responses to 1 ppm of NO2 amounted to about: 600% in N2/230% in air at 200 °C (in dark conditions and 430% in N2/340% in air at RT (with UV excitation. The response of the structure to the effect of NO2 at 200 °C is more than 105 times greater than the response to NH3, and more than 106 times greater than that to H2 in the relation of 1 ppm. Thus the selectivity of the structure for NO2 is very good. What is more, the selectivity to NO2 at RT with UV excitation increases in comparison at elevated temperature. This paper presents a great potential for practical applications of ZnO nanostructures (including nanoparticles in resistive NO2 sensors.

  1. PLD synthesis of GaN nanowires and nanodots on patterned catalyst surface for field emission study

    Ng, D.K.T.; Hong, M.H. [National University of Singapore (Singapore). Department of Electrical and Computer Engineering; Data Storage Institute, Singapore (Singapore); Tan, L.S. [National University of Singapore (Singapore). Department of Electrical and Computer Engineering; Zhu, Y.W.; Sow, C.H. [National University of Singapore (Singapore). Nanoscience and Nanotechnology Initiative; National University of Singapore (Singapore). Department of Physics

    2008-11-15

    Patterned gallium nitride nanowires and nanodots have been grown on n-Si(100) substrates by pulsed laser deposition. The nanostructures are patterned using a physical mask, resulting in regions of nanowire growth of different densities. The field emission (FE) characteristics of the patterned gallium nitride nanowires show a turn-on field of 9.06 V/{mu}m to achieve a current density of 0.01 mA/cm{sup 2} and an enhanced field emission current density as high as 0.156 mA/cm{sup 2} at an applied field of 11 V/{mu}m. Comparing the peak FE current densities of both the nanowires and nanodots, the peak FE current density of nanowires is around 700 times higher than that of the peak FE current density of nanodots since nanodots have a lower aspect ratio compared to nanowires. The field emission results indicate that, besides density difference, crystalline quality as well as the low electron affinity of gallium nitride, high aspect ratio of gallium nitride nanostructures will greatly enhance their field emission properties. (orig.)

  2. Formation Mechanism of Self Assembled Horizontal ErSb Nanowires Embedded in a GaSb(001) Matrix

    Wilson, Nathaniel; Kraemer, Stephan; PalmstrøM, Chris

    The ErxGa1-xSb exhibits a variety of self-assembling nanostructures. In order to harness these nanostructures for use in devices and other material systems it is important to understand their formation. We have characterized the growth mechanism of self-assembled horizontal ErSb nanowires in a GaSb(001) matrix through the use of in-situ Scanning Tunneling Microscopy (STM) as well as ex-situ Transmission Electron Microscopy (TEM). We observe large GaSb macrosteps on the growth surface of Er.3Ga.7Sb samples. The areas near the ledge and base of the macrosteps show significant differences in size and distribution of ErSb nanowires. Results suggest that the formation of macrosteps drives the transition from vertical to horizontal nanowires in the ErxGa1-xSb system. We also observe a low temperature growth mode, which results in horizontal nanowire formation under a wide range of flux conditions. This new growth mode does not exhibit the embedded growth observed in the formation of nanowires at higher temperatures and may allow for horizontal nanowire formation without the presence of macrosteps, as well as the formation of smaller nanoparticles which may be useful for achieving smaller nanoparticle dimensions and electron confinement effects. This work was supported by NSF-DMR under 1507875.

  3. Synthesis, structure and optical properties of single-crystalline In{sub 2}O{sub 3} nanowires

    Hadia, N.M.A., E-mail: nomery_abass@yahoo.com [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); Mohamed, H.A. [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); King Saud University, Teachers College, Science Department (Physics), 11148 Riyadh (Saudi Arabia)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Metal and metal oxide one dimensional (1D) nanostructured materials are of crucial importance. Black-Right-Pointing-Pointer The paper deals with the synthesis of In{sub 2}O{sub 3} nanowires without the use of catalysts. Black-Right-Pointing-Pointer The optical constants and Photoluminescence (PL) of In{sub 2}O{sub 3} nanowires were evaluated. - Abstract: Indium oxide In{sub 2}O{sub 3} nanowires have been recently synthesized revealing interesting properties and used in various applications. In order to reduce as much as possible the influence of undesired dopants and/or impurities on the observed properties, In{sub 2}O{sub 3} nanowires have been grown without the use of catalysts, directly from metallic indium by a vapor transport technique and a controlled oxidation with oxygen-argon mixtures. Depending on the growth conditions (temperature, vapor pressure, oxygen concentration, etc.) different results have been achieved and it has been observed that a 'proper' In condensation on the substrates may enhance the nanowires growth. Detailed structural analysis showed that the In{sub 2}O{sub 3} nanostructures are single crystalline with a cubic crystal structure. The grown In{sub 2}O{sub 3} nanowires were optically characterized in order to evaluate the absorption coefficient, optical band gap, refractive index and extinction coefficient. Room temperature Photoluminescence (PL) spectrum showed broad and intense blue emission at 375 nm.

  4. Facile Conversion Synthesis of Densely-Formed Branched ZnO-Nanowire Arrays for Quantum-Dot-Sensitized Solar Cells

    Lee, Woojin; Kang, Suji; Hwang, Taehyun; Kim, Kunsu; Woo, Hyungsub; Lee, Byungho; Kim, Jaewon; Kim, Jinhyun; Park, Byungwoo

    2015-01-01

    Highlights: •3-D hierarchically branched ZnO nanowires by a facile synthesis with seed nucleation. •Nanobranching enhances the efficiency by a factor of two compared with the bare QDSC. •Attributed to the increased sensitizer by ∼80% and decreased transmittance by ∼17%. •Optimized nanostructures correlate with the light-harvesting and carrier-collection efficiencies. -- Abstract: An effective way of synthesizing densely-formed branched ZnO-nanowire arrays was developed by a straightforward conversion reaction of ZnS into ZnO. Hierarchically structured ZnO nanowires are utilized for quantum-dot-sensitized solar cells (QDSCs), having resulted in the conversion-efficiency enhancement by a factor of two compared to the bare ZnO nanowires. This is attributed to the increased CdS-quantum-dot sensitizer by ∼80% and decreased diffused transmittance by ∼17%, induced by the densely-formed branched nanowires. The correlations between the branched nanostructures and photovoltaic performances are systematically investigated in terms of light absorption, charge-transfer resistance, and carrier lifetime. This facile and controllable branched nanowire synthesis is anticipated to be applicable to other semiconductor photoanodes for efficient light harvesting and charge collecting properties

  5. Misfit-guided self-organization of anti-correlated Ge quantum dot arrays on Si nanowires

    Kwon, Soonshin; Chen, Zack C.Y.; Kim, Ji-Hun; Xiang, Jie

    2012-01-01

    Misfit-strain guided growth of periodic quantum dot (QD) arrays in planar thin film epitaxy has been a popular nanostructure fabrication method. Engineering misfit-guided QD growth on a nanoscale substrate such as the small curvature surface of a nanowire represents a new approach to self-organized nanostructure preparation. Perhaps more profoundly, the periodic stress underlying each QD and the resulting modulation of electro-optical properties inside the nanowire backbone promise to provide a new platform for novel mechano-electronic, thermoelectronic, and optoelectronic devices. Herein, we report a first experimental demonstration of self-organized and self-limited growth of coherent, periodic Ge QDs on a one dimensional Si nanowire substrate. Systematic characterizations reveal several distinctively different modes of Ge QD ordering on the Si nanowire substrate depending on the core diameter. In particular, Ge QD arrays on Si nanowires of around 20 nm diameter predominantly exhibit an anti-correlated pattern whose wavelength agrees with theoretical predictions. The correlated pattern can be attributed to propagation and correlation of misfit strain across the diameter of the thin nanowire substrate. The QD array growth is self-limited as the wavelength of the QDs remains unchanged even after prolonged Ge deposition. Furthermore, we demonstrate a direct kinetic transformation from a uniform Ge shell layer to discrete QD arrays by a post-growth annealing process. PMID:22889063

  6. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection

    Ibupoto, Z.H., E-mail: zafar.hussin.ibupoto@liu.se [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden); Khun, K. [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden); Liu, X. [Department of Physics, Chemistry, and Biology (IFM), Linköping University, 58183 Linköping Sweden (Sweden); Willander, M. [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden)

    2013-10-15

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only Cu-O bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88 ± 0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10 s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. - Highlights: • This study describes the synthesis of bundle of CuO nanowires by hydrothermal method. • CuO nanostructures exhibit good alignment and

  7. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection

    Ibupoto, Z.H.; Khun, K.; Liu, X.; Willander, M.

    2013-01-01

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only Cu-O bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88 ± 0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10 s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. - Highlights: • This study describes the synthesis of bundle of CuO nanowires by hydrothermal method. • CuO nanostructures exhibit good alignment and

  8. Site-specific nucleation and controlled growth of a vertical tellurium nanowire array for high performance field emitters

    Safdar, Muhammad; Zhan Xueying; Mirza, Misbah; Wang Zhenxing; Sun Lianfeng; He Jun; Niu Mutong; Zhang Jinping; Zhao Qing

    2013-01-01

    We report the controlled growth of highly ordered and well aligned one-dimensional tellurium nanostructure arrays via a one-step catalyst-free physical vapor deposition method. The density, size and fine structures of tellurium nanowires are systematically studied and optimized. Field emission measurement was performed to display notable dependence on nanostructure morphologies. The ordered nanowire array based field emitter has a turn-on field as low as 3.27 V μm −1 and a higher field enhancement factor of 3270. Our finding offers the possibility of controlling the growth of tellurium nanowire arrays and opens up new means for their potential applications in electronic devices and displays. (paper)

  9. The Self- and Directed Assembly of Nanowires

    Smith, Benjamin David

    alignment with respect to nearest neighbor particles. All experiments showed order parameters indicating a slight preference for orientational ordering that was relatively insensitive to segment size, nanowire size, and nanowire coating. Monte Carlo simulations pointed towards this alignment as a consequence of small differences in the van der Waals attractions between the segments. Experimentally, ordering might to be limited by the large size of the nanowires, which results in kinetically trapped structures. In an attempt to obtain better ordering within rows, silica coated nanowires with partial Au cores were made. The synthesis involved silica-coating the nanowires and selectively etching a Ag segment. These particles have extremely different VDWs attractions between their segments, as the Au cores are much more attractive than the solvent-filled etched ends. The assembly of these partially etched nanowires (PENs) is detailed in Chapters 4, 5, and 6. When allowed to self-assemble, we observed the formation of either vertically or horizontally oriented arrays depending on PEN composition. The formation of vertically oriented arrays of anisotropic particles is important, since not many methods to produce these structures are currently available for particles of this size. We examined the effects of PEN length, PEN diameter, and the size, number, and location of the core segments. Our findings showed a large etched segment at one end (which resulted in a large offset in the center of mass and concentrated the VDWs attractions to one end of the particle) resulted in the best columnar assemblies. These vertically orientated arrays formed in a two part process. First, after PENs sedimented, they fell flat and oriented parallel to the surface. These PENs then sampled many orientations, including rotating out of the surface plane. When higher surface concentrations of particles built as more PENs fell to the surface of the cover slip, neighboring particles stabilized vertical

  10. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    Arto V. Nurmikko; Jung Han

    2007-03-31

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  11. W18O49 nanowires assembled on carbon felt for application to supercapacitors

    Jung, Jinjoo; Kim, Do Hyung

    2018-03-01

    For supercapacitor applications, W18O49 nanowires have been extensively grown on graphitic carbon felt using a facile solvothermal method. The diameter and length of the nanowires are about 7 and 300 nm, respectively. The nanowires consist of monoclinic W18O49 grown along the [010] direction, as shown by TEM and XRD analyses. The W18O49 nanowires, assembled on carbon felt, exhibit a high capacity of 588.33 F/g at a current density of 1 A/g together with an excellent cycle performance, and a low internal resistance during the electrochemical tests. This outstanding performance may originate from the three-dimensional porous nanostructure of these W18O49 nanowires, which leads to a reduction in the resistance and fast reaction kinetics due to the high specific surface area and electrolyte accessibility. Furthermore, sufficient oxygen deficiencies of the substoichiometric tungsten oxide can also contribute to the electrochemical activity, which can be confirmed by comparison of CV and EIS data with WO3 nanowires.

  12. Fabrication of silver nanowires via a β-cyclodextrin-derived soft template

    C. Y. Liu

    2018-07-01

    Full Text Available Supramolecular β-cyclodextrin (β-CD was used as a soft template for the fabrication of long silver nanowires. A novel design using self-assembled β-CD for the reduction of silver ions was studied. The concentrations of iron chloride, silver nitrate, and the template were controlling factors for the growth of the silver nanowires. Iron chloride was used to accelerate and facilitate the formation of the silver nanowires and inhibit oxidative etching. However, an excessive concentration of Fe+3 resulted in etching of the silver nanostructures. Furthermore, the silver concentration was another controlling factor. The length of the silver nanowires increased as the concentration of silver cations increased. Nevertheless, an excess concentration of silver cations formed various silver crystalline structures. In this study, the optimal ratio between iron chloride and silver nitrate was determined to be 1:13.3. A maximum length of 20 µm was achieved using a concentration of 0.23 M for the soft template. Moreover, the junction of two growing silver nanowires was observed, forming a long fused nanowire, and some significant boundaries were observed. The observed results were further confirmed using scanning electron microscopy (SEM and transmission electron microscopy (TEM analyses. X-ray diffraction (XRD and energy dispersive spectrometer (EDS analyses were used to indicate the presence of silver and the formation of crystalline materials.

  13. Fabrication of isolated platinum nanowire gratings and nanoparticles on silica substrate by femtosecond laser irradiation

    Nakajima, Yasutaka [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Nedyalkov, Nikolay [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shouse 72, Sofia 1784 (Bulgaria); Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan); Takami, Akihiro [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Terakawa, Mitsuhiro, E-mail: terakawa@elec.keio.ac.jp [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan)

    2017-02-01

    Highlights: • Formation of HSFL with periodicities shorter than 100 nm. • Structural evolution from platinum nanowire gratings to platinum nanoparticles only by increasing the number of pulses. • Melting and fragmentation of the nanowire gratings would play a key role in structural evolution. - Abstract: We demonstrate the fabrication of isolated platinum nanostructures on a silica substrate by using femtosecond laser. Nanowire gratings which have short periodicities of approximately 50 nm were formed by irradiating a platinum thin film deposited on a fused silica substrate with 800-nm wavelength femtosecond laser pulses. The structural evolution from the nanowire gratings to nanoparticles was observed only by increasing the number of pulses. The periodicities or diameters of the structures showed good uniformity. Scanning electron microscopy of the surfaces and theoretical calculation of temperature profile using a two-temperature model revealed that the structural evolution can be attributed to the fragmentation of the formed nanowires. The presented method provides a simple and high-throughput technique for fabricating both metal nanowire gratings and nanoparticles, which have the potential to be used for the fabrication of optical, electrical and biomedical devices.

  14. Excellent field emission properties of vertically oriented CuO nanowire films

    Long Feng

    2018-04-01

    Full Text Available Oriented CuO nanowire films were synthesized on a large scale using simple method of direct heating copper grids in air. The field emission properties of the sample can be enhanced by improving the aspect ratio of the nanowires just through a facile method of controlling the synthesis conditions. Although the density of the nanowires is large enough, the screen effect is not an important factor in this field emission process because few nanowires sticking out above the rest. Benefiting from the unique geometrical and structural features, the CuO nanowire samples show excellent field emission (FE properties. The FE measurements of CuO nanowire films illustrate that the sample synthesized at 500 °C for 8 h has a comparatively low turn-on field of 0.68 V/μm, a low threshold field of 1.1 V/μm, and a large field enhancement factor β of 16782 (a record high value for CuO nanostructures, to the best of our knowledge, indicating that the samples are promising candidates for field emission applications.

  15. Thermal-treatment effect on the photoluminescence and gas-sensing properties of tungsten oxide nanowires

    Sun, Shibin; Chang, Xueting; Li, Zhenjiang

    2010-01-01

    Single-crystalline non-stoichiometric tungsten oxide nanowires were initially prepared using a simple solvothermal method. High resolution transmission electron microscopy (HRTEM) investigations indicate that the tungsten oxide nanowires exhibit various crystal defects, including stacking faults, dislocations, and vacancies. A possible defect-induced mechanism was proposed to account for the temperature-dependent morphological evolution of the tungsten oxide nanowires under thermal processing. Due to the high specific surface areas and non-stoichiometric crystal structure, the original tungsten oxide nanowires were highly sensitive to ppm level ethanol at room temperature. Thermal treatment under dry air condition was found to deteriorate the selectivity of room-temperature tungsten oxide sensors, and 400 o C may be considered as the top temperature limit in sensor applications for the solvothermally-prepared nanowires. The photoluminescence (PL) characteristics of tungsten oxide nanowires were also strongly influenced by thermal treatment.

  16. Thermal-treatment effect on the photoluminescence and gas-sensing properties of tungsten oxide nanowires

    Sun, Shibin [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong (China); Chang, Xueting [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100, Shandong (China); Li, Zhenjiang, E-mail: zjli126@126.com [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong (China)

    2010-09-15

    Single-crystalline non-stoichiometric tungsten oxide nanowires were initially prepared using a simple solvothermal method. High resolution transmission electron microscopy (HRTEM) investigations indicate that the tungsten oxide nanowires exhibit various crystal defects, including stacking faults, dislocations, and vacancies. A possible defect-induced mechanism was proposed to account for the temperature-dependent morphological evolution of the tungsten oxide nanowires under thermal processing. Due to the high specific surface areas and non-stoichiometric crystal structure, the original tungsten oxide nanowires were highly sensitive to ppm level ethanol at room temperature. Thermal treatment under dry air condition was found to deteriorate the selectivity of room-temperature tungsten oxide sensors, and 400 {sup o}C may be considered as the top temperature limit in sensor applications for the solvothermally-prepared nanowires. The photoluminescence (PL) characteristics of tungsten oxide nanowires were also strongly influenced by thermal treatment.

  17. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection.

    Ibupoto, Z H; Khun, K; Liu, X; Willander, M

    2013-10-01

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only CuO bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88±0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Is there a shift to 'active nanostructures'?

    Subramanian, Vrishali; Youtie, Jan; Porter, Alan L.; Shapira, Philip

    2010-01-01

    It has been suggested that an important transition in the long-run trajectory of nanotechnology development is a shift from passive to active nanostructures. Such a shift could present different or increased societal impacts and require new approaches for risk assessment. An active nanostructure 'changes or evolves its state during its operation,' according to the National Science Foundation's (2006) Active Nanostructures and Nanosystems grant solicitation. Active nanostructure examples include nanoelectromechanical systems (NEMS), nanomachines, self-healing materials, targeted drugs and chemicals, energy storage devices, and sensors. This article considers two questions: (a) Is there a 'shift' to active nanostructures? (b) How can we characterize the prototypical areas into which active nanostructures may emerge? We build upon the NSF definition of active nanostructures to develop a research publication search strategy, with a particular intent to distinguish between passive and active nanotechnologies. We perform bibliometric analyses and describe the main publication trends from 1995 to 2008. We then describe the prototypes of research that emerge based on reading the abstracts and review papers encountered in our search. Preliminary results suggest that there is a sharp rise in active nanostructures publications in 2006, and this rise is maintained in 2007 and through to early 2008. We present a typology that can be used to describe the kind of active nanostructures that may be commercialized and regulated in the future.

  19. Is there a shift to "active nanostructures"?

    Subramanian, Vrishali; Youtie, Jan; Porter, Alan L.; Shapira, Philip

    2010-01-01

    It has been suggested that an important transition in the long-run trajectory of nanotechnology development is a shift from passive to active nanostructures. Such a shift could present different or increased societal impacts and require new approaches for risk assessment. An active nanostructure "changes or evolves its state during its operation," according to the National Science Foundation's (2006) Active Nanostructures and Nanosystems grant solicitation. Active nanostructure examples include nanoelectromechanical systems (NEMS), nanomachines, self-healing materials, targeted drugs and chemicals, energy storage devices, and sensors. This article considers two questions: (a) Is there a "shift" to active nanostructures? (b) How can we characterize the prototypical areas into which active nanostructures may emerge? We build upon the NSF definition of active nanostructures to develop a research publication search strategy, with a particular intent to distinguish between passive and active nanotechnologies. We perform bibliometric analyses and describe the main publication trends from 1995 to 2008. We then describe the prototypes of research that emerge based on reading the abstracts and review papers encountered in our search. Preliminary results suggest that there is a sharp rise in active nanostructures publications in 2006, and this rise is maintained in 2007 and through to early 2008. We present a typology that can be used to describe the kind of active nanostructures that may be commercialized and regulated in the future.

  20. Radial composition of single InGaN nanowires: a combined study by EDX, Raman spectroscopy, and X-ray diffraction

    Gomez-Gomez, M.; Garro, N.; Cantarero, A. [Institut de Ciencia dels Materials, Universitat de Valencia, Paterna (Spain); Segura-Ruiz, J.; Martinez-Criado, G.; Chu, M.H. [European Synchrotron Radiation Facility, Experiments Division, Grenoble (France); Denker, C.; Malindretos, J.; Rizzi, A. [IV. Physikalisches Institut, Georg-August-Universitaet Goettingen (Germany)

    2013-10-15

    The radial alloy distribution of In{sub x} Ga{sub 1-x}N nanowires grown by plasma-assisted molecular beam epitaxy has been investigated by three different techniques with nanometric spatial resolution and capability to study single nanowires. Energy-dispersive X-ray spectroscopy radial line-scans revealed a gradient in the alloy composition of individual nanowires. Resonant Raman scattering and spatially resolved X-ray diffraction showed the existence of three distinctive regions with different alloy composition. The combination of the three techniques provides robust evidence of the spontaneous formation of a core-shell structure with a thin Ga-richer shell wrapping an In-rich core at the bottom part of the nanowires. This composition-modulated nanostructure offers an attractive way to explore new device concepts in fully epitaxial nanowire-based solar cells. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Radial composition of single InGaN nanowires: a combined study by EDX, Raman spectroscopy, and X-ray diffraction

    Gomez-Gomez, M.; Garro, N.; Cantarero, A.; Segura-Ruiz, J.; Martinez-Criado, G.; Chu, M.H.; Denker, C.; Malindretos, J.; Rizzi, A.

    2013-01-01

    The radial alloy distribution of In x Ga 1-x N nanowires grown by plasma-assisted molecular beam epitaxy has been investigated by three different techniques with nanometric spatial resolution and capability to study single nanowires. Energy-dispersive X-ray spectroscopy radial line-scans revealed a gradient in the alloy composition of individual nanowires. Resonant Raman scattering and spatially resolved X-ray diffraction showed the existence of three distinctive regions with different alloy composition. The combination of the three techniques provides robust evidence of the spontaneous formation of a core-shell structure with a thin Ga-richer shell wrapping an In-rich core at the bottom part of the nanowires. This composition-modulated nanostructure offers an attractive way to explore new device concepts in fully epitaxial nanowire-based solar cells. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Topological Insulator Nanowires and Nanoribbons

    Kong, Desheng

    2010-01-13

    Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi2Se3 material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi2Se5 nanomaterials with a variety of morphologies. The synthesis of Bi 2Se5 nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [1120] direction with a rectangular cross-section and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with ∼ 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitais to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states. © 2010 American Chemical Society.

  3. Microwave-assisted aqueous synthesis of ultralong ZnO nanowires: photoluminescence and photovoltaic performance for dye-sensitized solar cell

    Min, C.; Shen, X.; Sheng, W. [Jiangsu University, School of Materials Science and Engineering, Zhenjiang (China)

    2009-09-15

    Ultralong ZnO nanowires were successfully prepared on a large scale by a microwave-assisted aqueous route without using any surfactant or template at relatively low temperature of 120 C. The obtained nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectrum (EDX). The growth mechanism and photoluminescence of the one-dimensional nanostructure, and photovoltaic performances for dye-sensitized solar cell (DSSC) of the nanowires were discussed in detail. (orig.)

  4. Cytotoxicity and intracellular dissolution of nickel nanowires

    Perez, Jose E.

    2015-12-22

    The assessment of cytotoxicity of nanostructures is a fundamental step for their development as biomedical tools. As widely used nanostructures, nickel nanowires (Ni NWs) seem promising candidates for such applications. In this work, Ni NWs were synthesized and then characterized using vibrating sample magnetometry, energy dispersive X-Ray analysis and electron microscopy. After exposure to the NWs, cytotoxicity was evaluated in terms of cell viability, cell membrane damage and induced apoptosis/necrosis on the model human cell line HCT 116. The influence of NW to cell ratio (10:1 to 1000:1) and exposure times up to 72 hours was analyzed for Ni NWs of 5.4 µm in length, as well as for Ni ions. The results show that cytotoxicity markedly increases past 24 hours of incubation. Cellular uptake of NWs takes place through the phagocytosis pathway, with a fraction of the dose of NWs dissolved inside the cells. Cell death results from a combination of apoptosis and necrosis, where the latter is the outcome of the secondary necrosis pathway. The cytotoxicity of Ni ions and Ni NWs dissolution studies suggest a synergistic toxicity between NW aspect ratio and dissolved Ni, with the cytotoxic effects markedly increasing after 24 hours of incubation.

  5. Cytotoxicity and intracellular dissolution of nickel nanowires.

    Perez, Jose E; Contreras, Maria F; Vilanova, Enrique; Felix, Laura P; Margineanu, Michael B; Luongo, Giovanni; Porter, Alexandra E; Dunlop, Iain E; Ravasi, Timothy; Kosel, Jürgen

    2016-09-01

    The assessment of cytotoxicity of nanostructures is a fundamental step for their development as biomedical tools. As widely used nanostructures, nickel nanowires (Ni NWs) seem promising candidates for such applications. In this work, Ni NWs were synthesized and then characterized using vibrating sample magnetometry, energy dispersive X-Ray analysis, and electron microscopy. After exposure to the NWs, cytotoxicity was evaluated in terms of cell viability, cell membrane damage, and induced apoptosis/necrosis on the model human cell line HCT 116. The influence of NW to cell ratio (10:1 to 1000:1) and exposure times up to 72 hours was analyzed for Ni NWs of 5.4 μm in length, as well as for Ni ions. The results show that cytotoxicity markedly increases past 24 hours of incubation. Cellular uptake of NWs takes place through the phagocytosis pathway, with a fraction of the dose of NWs dissolved inside the cells. Cell death results from a combination of apoptosis and necrosis, where the latter is the outcome of the secondary necrosis pathway. The cytotoxicity of Ni ions and Ni NWs dissolution studies suggest a synergistic toxicity between NW aspect ratio and dissolved Ni, with the cytotoxic effects markedly increasing after 24 hours of incubation.

  6. Cytotoxicity and intracellular dissolution of nickel nanowires

    Perez, Jose E.; Contreras, Maria F.; Vidal, Enrique Vilanova; Felix Servin, Laura P.; Margineanu, Michael B.; Luongo, Giovanni; Porter, Alexandra E.; Dunlop, Iain E.; Ravasi, Timothy; Kosel, Jü rgen

    2015-01-01

    The assessment of cytotoxicity of nanostructures is a fundamental step for their development as biomedical tools. As widely used nanostructures, nickel nanowires (Ni NWs) seem promising candidates for such applications. In this work, Ni NWs were synthesized and then characterized using vibrating sample magnetometry, energy dispersive X-Ray analysis and electron microscopy. After exposure to the NWs, cytotoxicity was evaluated in terms of cell viability, cell membrane damage and induced apoptosis/necrosis on the model human cell line HCT 116. The influence of NW to cell ratio (10:1 to 1000:1) and exposure times up to 72 hours was analyzed for Ni NWs of 5.4 µm in length, as well as for Ni ions. The results show that cytotoxicity markedly increases past 24 hours of incubation. Cellular uptake of NWs takes place through the phagocytosis pathway, with a fraction of the dose of NWs dissolved inside the cells. Cell death results from a combination of apoptosis and necrosis, where the latter is the outcome of the secondary necrosis pathway. The cytotoxicity of Ni ions and Ni NWs dissolution studies suggest a synergistic toxicity between NW aspect ratio and dissolved Ni, with the cytotoxic effects markedly increasing after 24 hours of incubation.

  7. Nanostructured transparent conducting oxide electrochromic device

    Milliron, Delia; Tangirala, Ravisubhash; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

    2016-05-17

    The embodiments described herein provide an electrochromic device. In an exemplary embodiment, the electrochromic device includes (1) a substrate and (2) a film supported by the substrate, where the film includes transparent conducting oxide (TCO) nanostructures. In a further embodiment, the electrochromic device further includes (a) an electrolyte, where the nanostructures are embedded in the electrolyte, resulting in an electrolyte, nanostructure mixture positioned above the substrate and (b) a counter electrode positioned above the mixture. In a further embodiment, the electrochromic device further includes a conductive coating deposited on the substrate between the substrate and the mixture. In a further embodiment, the electrochromic device further includes a second substrate positioned above the mixture.

  8. Urchin-like artificial gallium oxide nanowires grown by a novel MOCVD/CVD-based route for random laser application

    Melo, Ronaldo P. de [Programa de Pós-Graduação em Ciências de Materiais, Universidade Federal de Pernambuco, Recife (Brazil); Colégio Militar do Recife, Exército Brasileiro, Recife PE 50730-120 (Brazil); Oliveira, Nathalia Talita C. [Programa de Pós-Graduação em Ciências de Materiais, Universidade Federal de Pernambuco, Recife (Brazil); Dominguez, Christian Tolentino; Gomes, Anderson S. L.; Araújo, Cid B. de [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife (Brazil); Falcão, Eduardo H. L.; Alves, Severino; Luz, Leonis L. da [Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50670-901 Recife (Brazil); Chassagnon, Remi [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Av. A. Savary, BP 47870, 21078 Dijon Cedex (France); Sacilotti, Marco [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife (Brazil); Nanoform Group, Laboratoire Interdisciplinaire Carnot de Bourgogne, Université de Bourgogne, Dijon (France)

    2016-04-28

    A novel procedure based on a two-step method was developed to obtain β-Ga{sub 2}O{sub 3} nanowires by the chemical vapor deposition (CVD) method. The first step consists in the gallium micro-spheres growth inside a metal-organic chemical vapor deposition environment, using an organometallic precursor. Nanoscale spheres covering the microspheres were obtained. The second step involves the CVD oxidization of the gallium micro-spheres, which allow the formation of β-Ga{sub 2}O{sub 3} nanowires on the micro-sphere surface, with the final result being a nanostructure mimicking nature's sea urchin morphology. The grown nanomaterial is characterized by several techniques, including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, and photoluminescence. A discussion about the growth mechanism and the optical properties of the β-Ga{sub 2}O{sub 3} material is presented considering its unknown true bandgap value (extending from 4.4 to 5.68 eV). As an application, the scattering properties of the nanomaterial are exploited to demonstrate random laser emission (around 570 nm) when it is permeated with a laser dye liquid solution.

  9. High-performance supercapacitors of Cu-based porous coordination polymer nanowires and the derived porous CuO nanotubes.

    Wu, Meng-Ke; Zhou, Jiao-Jiao; Yi, Fei-Yan; Chen, Chen; Li, Yan-Li; Li, Qin; Tao, Kai; Han, Lei

    2017-12-12

    Electrode materials for supercapacitors with one-dimensional porous nanostructures, such as nanowires and nanotubes, are very attractive for high-efficiency storage of electrochemical energy. Herein, ultralong Cu-based porous coordination polymer nanowires (copper-l-aspartic acid) were used as the electrode material for supercapacitors, for the first time. The as-prepared material exhibits a high specific capacitance of 367 F g -1 at 0.6 A g -1 and excellent cycling stability (94% retention over 1000 cycles). Moreover, porous CuO nanotubes were successfully fabricated by the thermal decomposition of this nanowire precursor. The CuO nanotube exhibits good electrochemical performance with high rate capacity (77% retention at 12.5 A g -1 ) and long-term stability (96% retention over 1000 cycles). The strategy developed here for the synthesis of porous nanowires and nanotubes can be extended to the construction of other electrode materials for more efficient energy storage.

  10. Growth of uranyl hydroxide nanowires and nanotubes with electrodeposition method

    Wang Lin; Yuan Liyong; Chai Zhifang; Shi Weiqun

    2013-01-01

    Actinides nanomaterials have great potential applications in fabrication of novel nuclear fuel and spent fuel reprocessing in advanced nuclear energy system. However, the relative research so far still lacks systematic investigation on the synthetic methods for actinides nanomaterials. In this work, we use track-etched membranes as hard templates to synthesize uranium based nanomaterials with novel structures by electrodeposition method. Through electrochemical behavior investigations and subsequent product characterizations such as energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FTIR), the chemical composition of deposition products have been confirmed as the uranyl hydroxide. More importantly, accurate control of morphology and structures (nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and deposition current density. It was found that the preferred morphology of electrodeposition products is nanowire when a low current density was applied, whereas nanotubes could be formed only under conditions of high current density and the short deposition time. The mechanism for the formation of nanowires in track-etched membranes is based on the precipitation of uranyl hydroxide from uranyl nitrate solution, according to the previous researches about obtaining nanostructures of hydroxides from nitrate salt solutions. And we have concluded that the formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the condition of over-potential electro-reduction. The conveying of hydrogen bubbles plays the role of dynamic template which can prevent the complete filling of uranyl hydroxide in the channels. Additionally, we transform the chemical composition of deposition products from uranyl hydroxide to triuranium octoxide by calcining them at 500 and 800 degree centigrade, respectively, and SEM results show the morphologies of nanowires and

  11. Superhydrophobic SERS substrates based on silicon hierarchical nanostructures

    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

  12. Enhancement of Si solar cell efficiency using ZnO nanowires with various diameters

    Gholizadeh, A.; Reyhani, A.; Parvin, P.; Mortazavi, S. Z.; Mehrabi, M.

    2018-01-01

    Here, Zinc Oxide nanowires are synthesized using thermal chemical vapor deposition of a Zn granulate source and used to enhance a significant Si-solar cell efficiency with simple and low cost method. The nanowires are grown in various O2 flow rates. Those affect the shape, yield, structure and the quality of ZnO nanowires according to scanning electron microscopy and x-ray diffraction analyses. This delineates that the ZnO nanostructure is dependent on the synthesis conditions. The photoluminescence spectroscopy of ZnO indicates optical emission at the Ultra-Violet and blue-green regions whose intensity varies as a function of diameter of ZnO nano-wires. The optical property of ZnO layer is measured by UV-visible and diffuse reflection spectroscopy that demonstrate high absorbance at 280-550 nm. Furthermore, the photovoltaic characterization of ZnO nanowires is investigated based on the drop casting on Si-solar cell. The ZnO nanowires with various diameters demonstrate different effects on the efficiency of Si-solar cells. We have shown that the reduction of the spectral reflectance and down-shifting process as well as the reduction of photon trapping are essential parameters on the efficiency of Si-solar cells. However, the latter is dominated here. In fact, the trapped photons during the electron-hole generation are dominant due to lessening the absorption rate in ZnO nano-wires. The results indicate that the mean diameters reduction of ZnO nanowires is also essential to improve the fill factor. The external and internal quantum efficiency analyses attest the efficiency improvement over the blue region which is related to the key parameters above.

  13. PREFACE: Nanostructured surfaces

    Palmer, Richard E.

    2003-10-01

    devices, respectively, while the papers by Ledieu and Guo report the structural characterization of novel surface systems—quasicrystal surfaces and supramolecular monolayers, respectively. The final two papers, by Bennett and Smith, demonstrate the positive interplay between experimental measurements and theoretical modelling in the investigation of nanostructured surfaces. The examples discussed include, respectively, the growth of metal clusters on oxide surfaces and the deposition of fullerenes and energetic clusters from the gas phase. We note finally that the last six papers in this special issue have been contributed by members of the Committee of the newly-formed Nanoscale Physics and Technology Group of the Institute of Physics. The Group shares with this special issue the aim of promoting and disseminating exciting advances in the flourishing field of nanoscale physics.

  14. The ITO-capped WO3 nanowires biosensor based on field-effect transistor in label-free protein sensing

    Shariati, Mohsen

    2017-01-01

    The fabrication of ITO-capped WO 3 nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO 3 nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was 'label-free' and depended on bio-molecule's intrinsic charge. For nanowires synthesis, the vapor-liquid-solid mechanism was used. Nanowires were beyond a few hundred nanometers in lengths and around 15-20 nm in diameter, while the globe cap's size on the nanowires was around 15-25 nm. The indium tin oxide (ITO) played as catalyst in nanofabrication for WO 3 nanowires growth and had outstanding role in bio-sensing especially for bio-molecule adherence. In applied electric field presence, the fabricated device showed the great potential to enhance medical diagnostics. (orig.)

  15. Packaging glass with hierarchically nanostructured surface

    He, Jr-Hau

    2017-08-03

    An optical device includes an active region and packaging glass located on top of the active region. A top surface of the packaging glass includes hierarchical nanostructures comprised of honeycombed nanowalls (HNWs) and nanorod (NR) structures extending from the HNWs.

  16. Packaging glass with hierarchically nanostructured surface

    He, Jr-Hau; Fu, Hui-Chun

    2017-01-01

    An optical device includes an active region and packaging glass located on top of the active region. A top surface of the packaging glass includes hierarchical nanostructures comprised of honeycombed nanowalls (HNWs) and nanorod (NR) structures

  17. Production of nanopoints and nanowires of silver at the surface of Si(557)

    Zhachuk, R.A.; Tijs, S.A.; Ol'shanetskij, B.Z.

    2004-01-01

    Formation of the silver nanostructures at the room temperature on the Si(557) surface containing the regular atomic stages of three interplanar distances in the height is studied through the methods of the scanning tunnel microscopy and electron Auger-spectroscopy. It is established that the oxygen adsorbed by the silicon surface from the residual atmosphere in the vacuum chamber effects the shape of the formed silver islands. The silver nanostructures of the nanowire-type, extended along the stage edges or nanopoints ordered in lines parallel to the stage edges may be formed depending on the quantity of the oxygen adsorbed on the surface [ru

  18. Mapping the Complex Morphology of Cell Interactions with Nanowire Substrates Using FIB-SEM

    Wierzbicki, Rafal; Købler, Carsten; Jensen, Mikkel Ravn Boye

    2013-01-01

    Using high resolution focused ion beam scanning electron microscopy (FIB-SEM) we study the details of cell-nanostructure interactions using serial block face imaging. 3T3 Fibroblast cellular monolayers are cultured on flat glass as a control surface and on two types of nanostructured scaffold...... substrates made from silicon black (Nanograss) with low- and high nanowire density. After culturing for 72 hours the cells were fixed, heavy metal stained, embedded in resin, and processed with FIB-SEM block face imaging without removing the substrate. The sample preparation procedure, image acquisition...

  19. Nanostructures: A Platform for Brain Repair and Augmentation

    Ruxandra eVidu

    2014-06-01

    Full Text Available Nanoscale structures have been at the core of research efforts dealing with integration of nanotechnology into novel electronic devices for the last decade. For instance, the unique electrical and optical properties of nanowires, nanotubes and nanocables with vertical orientation, assembled in nanoscale arrays, have been used in many device applications such as sensors that hold the potential to augment brain functions. However, the challenge in creating nanowires/nanotubes or nanocables arrays based sensors lies in making individual electrical connections fitting both the features of the brain and of the nanostructures. This review discusses two of the most important applications of nanostructures in neuroscience. First, the current approaches to create nanowires and nanocable structures are reviewed to critically evaluate their potential of developing unique nanostructure based sensors to improve recording and device performance to reduce noise and the detrimental effect of the interface on the tissue. Second, the implementation of nanomaterials in neurobiological and medical applications will be considered from the brain augmentation perspective. Because the size of nanomaterials is of the same order of magnitude with that of biomolecules, these materials are valuable tools for nanoscale manipulation in a broad range of neurobiological systems. Novel applications for diagnosis and treatment of brain diseases such as multiple sclerosis, meningitis, stroke, epilepsy, Alzheimer disease, schizophrenia, and autism will be considered. Because the blood brain barrier (BBB has a defensive mechanism in preventing nanomaterials arrival to the brain, various strategies to help them to passing through the BBB will be discussed. The nanostructures at the interface between nanotechnology and neuroscience will play a pivotal role not only in addressing the multitude of brain disorders but also to repair/augment brain functions.

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

    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. Growth Mechanism of Nanowires: Binary and Ternary Chalcogenides

    Singh, N. B.; Coriell, S. R.; Su, Ching-Hua; Hopkins, R. H.; Arnold, B.; Choa, Fow-Sen; Cullum, Brian

    2016-01-01

    Semiconductor nanowires exhibit very exciting optical and electrical properties including high transparency and a several order of magnitude better photocurrent than thin film and bulk materials. We present here the mechanism of nanowire growth from the melt-liquid-vapor medium. We describe preliminary results of binary and ternary selenide materials in light of recent theories. Experiments were performed with lead selenide and thallium arsenic selenide systems which are multifunctional material and have been used for detectors, acousto-optical, nonlinear and radiation detection applications. We observed that small units of nanocubes and elongated nanoparticles arrange and rearrange at moderate melt undercooling to form the building block of a nanowire. Since we avoided the catalyst, we observed self-nucleation and uncontrolled growth of wires from different places. Growth of lead selenide nanowires was performed by physical vapor transport method and thallium arsenic selenide nanowire by vapor-liquid-solid (VLS) method. In some cases very long wires (>mm) are formed. To achieve this goal experiments were performed to create situation where nanowires grew on the surface of solid thallium arsenic selenide itself.

  2. Young's Modulus of Wurtzite and Zinc Blende InP Nanowires.

    Dunaevskiy, Mikhail; Geydt, Pavel; Lähderanta, Erkki; Alekseev, Prokhor; Haggrén, Tuomas; Kakko, Joona-Pekko; Jiang, Hua; Lipsanen, Harri

    2017-06-14

    The Young's modulus of thin conical InP nanowires with either wurtzite or mixed "zinc blende/wurtzite" structures was measured. It has been shown that the value of Young's modulus obtained for wurtzite InP nanowires (E [0001] = 130 ± 30 GPa) was similar to the theoretically predicted value for the wurtzite InP material (E [0001] = 120 ± 10 GPa). The Young's modulus of mixed "zinc blende/wurtzite" InP nanowires (E [111] = 65 ± 10 GPa) appeared to be 40% less than the theoretically predicted value for the zinc blende InP material (E [111] = 110 GPa). An advanced method for measuring the Young's modulus of thin and flexible nanostructures is proposed. It consists of measuring the flexibility (the inverse of stiffness) profiles 1/k(x) by the scanning probe microscopy with precise control of loading force in nanonewton range followed by simulations.

  3. Characterization and Growth Mechanism of Nickel Nanowires Resulting from Reduction of Nickel Formate in Polyol Medium

    Olga A. Logutenko

    2016-01-01

    Full Text Available Nickel linear nanostructures were synthesized by reduction of nickel formate with hydrazine hydrate in ethylene glycol medium in the absence of any surfactants or capping agents for direction of the particles growth. The effect of the synthesis conditions such as temperature, reduction time, type of polyol, and nickel formate concentration on the reduction products was studied. The size and morphology of the nickel nanowires were characterized by X-ray diffraction, scanning, and transmission electron microscopy. It was shown that the nickel nanocrystallites were wire-shaped with a face-center-cubic phase. Ethylene glycol was found to play a crucial role in the formation of the nickel nanowires. The possible growth processes of the wire-shaped particles taking place at 110 and 130°C are discussed. It was shown that, under certain synthesis conditions, nickel nanowires grow on the surface of the crystals of the solid intermediate of nickel with hydrazine hydrate.

  4. Growth and optical properties of CdTe quantum dots in ZnTe nanowires

    Wojnar, Piotr; Janik, Elzbieta; Baczewski, Lech T.; Kret, Slawomir; Karczewski, G.; Wojtowicz, Tomasz [Institute of Physics, Polish Academy of Sciences, Al Lotnikow 32/46, 02-668 Warsaw (Poland); Goryca, Mateusz; Kazimierczuk, Tomasz; Kossacki, Piotr [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul Hoza 69, 00-681 Warsaw (Poland)

    2011-09-12

    We report on the formation of optically active CdTe quantum dots in ZnTe nanowires. The CdTe/ZnTe nanostructures have been grown by a gold nanocatalyst assisted molecular beam epitaxy in a vapor-liquid solid growth process. The presence of CdTe insertions in ZnTe nanowire results in the appearance of a strong photoluminescence band in the 2.0 eV-2.25 eV energy range. Spatially resolved photoluminescence measurements reveal that this broad emission consists of several sharp lines with the spectral width of about 2 meV. The large degree of linear polarization of these individual emission lines confirms their nanowire origin, whereas the zero-dimensional confinement is proved by photon correlation spectroscopy.

  5. Comparison of multilayered nanowire imaging by SEM and Helium Ion Microscopy

    Inkson, B J; Peng, Y; Jepson, M A E; Rodenburg, C; Liu, X

    2010-01-01

    The helium ion microscope (HeIM) is capable of probe sizes smaller than SEM and, with intrinsically small ion/sample interaction volumes, may therefore potentially offer higher spatial resolution secondary electron (SE) imaging of nanostructures. Here 55 nm diameter CoPt/Pt multilayered nanowires have been imaged by HeIM, SEM and TEM. It is found that there is an increased resolution of nanowire surface topography in HeIM SE images compared to SEM, however there is a reduction of materials contrast of the alternating Pt and CoPt layers. This can be attributed to the increased contribution of surface contamination layers to the ion-induced SE signal, and carbon is also observed to grow on the nanowires under prolonged HeIM scanning.

  6. Scaling behavior of the thermal conductivity of width-modulated nanowires and nanofilms for heat transfer control at the nanoscale.

    Zianni, Xanthippi; Jean, Valentin; Termentzidis, Konstantinos; Lacroix, David

    2014-11-21

    We report on scaling behavior of the thermal conductivity of width-modulated nanowires and nanofilms that have been studied with the phonon Monte Carlo technique. It has been found that the reduction of the thermal conductivity scales with the nanostructure transmissivity, a property entirely determined by the modulation geometry, irrespectively of the material choice. Tuning of the thermal conductivity is possible by the nanostructure width-modulation without strict limitations for the modulation profile. In addition, a very significant constriction thermal resistance due to width-discontinuity has been identified, in analogy to the contact thermal resistance between two dissimilar materials. The constriction thermal resistance also scales with the modulated nanostructure transmissivity. Our conclusions are generic indicating that a wide range of materials can be used for the modulated nanostructures. Direct heat flow control can be provided by designing the nanostructure width-modulation.

  7. Long Silver Nanowires Synthesis by Pulsed Electrodeposition

    M.R. Batevandi

    2015-09-01

    Full Text Available Silver nanowires were pulse electrodeposited into nanopore anodic alumina oxide templates. The effects of continuous and pulse electrodeposition waveform on the microstructure properties of the nanowire arrays were studied. It is seen that the microstructure of nanowire is depend to pulse condition. The off time duration of pulse waveform enables to control the growth direction of Ag nanowires.

  8. Characterization of Nanostructured Semiconductors by Ultrafast Luminescence Imaging

    Blake, Jolie

    Single nanostructures are predicted to be the building blocks of next generation devices and have already been incorporated into prototypes for solar cells, biomedical devices and lasers. Their role in such applications requires a fundamental understanding of their opto-electronic properties and in particular the charge carrier dynamics occurring on an ultrafast timescale. Luminescence detection is a common approach used to investigate electronic properties of nanostructures because of the contact-less nature of these methods. They are, however, often not equipped to efficiently measure multiple single nanostructures nor do they have the temporal resolution necessary for observing femtosecond dynamics. This dissertation intends to address this paucity of techniques available for the contact-less measurement of single nanostructures through the development of an ultrafast wide-field Kerr-gated microscope system and measurement technique. The setup, operational in both the steady state and transient mode and capable of microscopic and spectroscopic measurements, was developed to measure the transient luminescence of single semiconductor nanostructures. With sub micron spatial resolution and the potential to achieve a temporal resolution greater than 90 fs, the system was used to probe the charge carrier dynamics at multiple discrete locations on single nanowires exhibiting amplified spontaneous emission. Using a rate model for amplified spontaneous emission, the transient emission data was fitted to extract the values of the competing Shockley-Read-Hall, non-geminate and Auger recombination constants. The capabilities of the setup were first demonstrated in the visible detection range, where single nanowires of the ternary alloy CdS x Se1-x were measured. The temporal emission dynamics at two separate locations were compared and calculation of the Langevin mobility revealed that the large carrier densities generated in the nanowire allows access to non

  9. Aging of Organic Nanowires

    Balzer, Frank; Schiek, Manuela; Osadnik, Andreas

    2012-01-01

    Organic semiconductors formed by epitaxial growth from small molecules such as the para-phenylenes or squaraines promise a vast application potential as the active ingredient in electric and optoelectronic devices. Their self-organization into organic nanowires or "nanofibers" adds a peculiar...... attribute, making them especially interesting for light generation in OLEDs and for light-harvesting devices such as solar cells. Functionalization of the molecules allows the customization of optical and electrical properties. However, aging of the wires might lead to a considerable decrease in device...... performance over time. In this study the morphological stability of organic nanoclusters and nanowires from the methoxy functionalized quaterphenylene, 4,4'''dimethoxy-1,1':4',1''4'',1'''-quaterphenylene (MOP4), is investigated in detail. Aging experiments conducted by atomic force microscopy under ambient...

  10. Self-assembled quantum dot structures in a hexagonal nanowire for quantum photonics.

    Yu, Ying; Dou, Xiu-Ming; Wei, Bin; Zha, Guo-Wei; Shang, Xiang-Jun; Wang, Li; Su, Dan; Xu, Jian-Xing; Wang, Hai-Yan; Ni, Hai-Qiao; Sun, Bao-Quan; Ji, Yuan; Han, Xiao-Dong; Niu, Zhi-Chuan

    2014-05-01

    Two types of quantum nanostructures based on self-assembled GaAs quantumdots embedded into GaAs/AlGaAs hexagonal nanowire systems are reported, opening a new avenue to the fabrication of highly efficient single-photon sources, as well as the design of novel quantum optics experiments and robust quantum optoelectronic devices operating at higher temperature, which are required for practical quantum photonics applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Characterization and Growth Mechanism of Nickel Nanowires Resulting from Reduction of Nickel Formate in Polyol Medium

    Logutenko, Olga A.; Titkov, Alexander I.; Vorob’yov, Alexander M.; Yukhin, Yriy M.; Lyakhov, Nikolay Z.

    2016-01-01

    Nickel linear nanostructures were synthesized by reduction of nickel formate with hydrazine hydrate in ethylene glycol medium in the absence of any surfactants or capping agents for direction of the particles growth. The effect of the synthesis conditions such as temperature, reduction time, type of polyol, and nickel formate concentration on the reduction products was studied. The size and morphology of the nickel nanowires were characterized by X-ray diffraction, scanning, and transmission ...

  12. Controlling the Coupling of a Single Nitrogen Vacancy Center to a Silver Nanowire

    Huck, Alexander; Kumar, Shailesh; Shakoor, Abdul

    2011-01-01

    Dipole emitters are expected to efficiently couple to the plasmonic mode propagating along a cylindrically shaped metallic nano-structure. Such a strongly coupled system could serve as a fundamental building block for a single photon source on demand and a device enabling strong non-linear intera...... control over the relative nanowire diamond nano-crystal position is achieved by using an atomic force microscope (AFM) in contact mode operation....

  13. Characterization of Nanowire Photodetectors

    2016-11-28

    characterization system and picosecond pulsed laser source will be used to provide deeper insight into the fast charge carrier dynamics in the GaAsSb and...value of the current fluctuations for a particular frequency, f is the effective measurement bandwidth at the discrete frequency point, and IDS is...GaAsSb CS nanowires. The best fit of the spectra with the simulation carried out using Matlab revealed flicker noise at lower frequency having 1/f

  14. Direct observation of Au/Ga2O3 peapodded nanowires and their plasmonic behaviors.

    Chen, Po-Han; Hsieh, Chin-Hua; Chen, Sheng-Yu; Wu, Chen-Hwa; Wu, Yi-Jen; Chou, Li-Jen; Chen, Lih-Juann

    2010-09-08

    Gold-peapodded Ga(2)O(3) nanowires were fabricated successfully in a well-controlled manner by thermal annealing of core-shell gold-Ga(2)O(3) nanowires. During the heating process, the core gold nanowires were broken up into chains of nanoparticles at sufficiently high temperature by the mechanism of Rayleigh instability. In addition, the size, shape, and interspacing between the particles can be manipulated by varying the annealing time and/or the forming gas. The plasmonic behaviors of these nanostructures are investigated by optical spectroscopy. A single nanowire optical device was designed, and its photonic characteristics were investigated. A remarkably high on/off photocurrent ratio in response to a 532 nm Nd:YAG laser light was found. As the size of the particle (pea) increases, the corresponding spectra are red-shifted. In addition, morphological changes of the peas lead to a distinct spectral response. The results may usher in the diverse applications in optoelectronics and biosensing devices with peapod nanostructures.

  15. Fabrication and optical properties of multishell InAs quantum dots on GaAs nanowires

    Yan, Xin; Zhang, Xia, E-mail: xzhang@bupt.edu.cn; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2015-02-07

    Hybrid nanostructures combining nanowires with quantum dots promote the development of nanoelectronic and nanophotonic devices with integrated functionalities. In this work, we present a complex nanostructure with multishell quantum dots grown on nanowires. 1–4 shells of Stranski-Krastanov InAs quantum dots are grown on the sidewalls of GaAs nanowires by metal organic chemical vapor deposition. Different dot shells are separated by 8 nm GaAs spacer shells. With increasing the number of shells, the quantum dots become sparser and tend to align in one array, which is caused by the shrinkage of facets on which dots prefer to grow as well as the strain fields produced by the lower set of dots which influences the migration of In adatoms. The size of quantum dots increases with the increase of shell number due to enhanced strain fields coupling. The spectra of multishell dots exhibit multiwavelength emission, and each peak corresponds to a dot shell. This hybrid structure may serve as a promising element in nanowire intermediate band solar cells, infrared nanolasers, and photodetectors.

  16. Self-powered heat-resistant polymeric 1D nanowires and 3D micro/nanowire assemblies in a pressure-crystallized size-distributed graphene oxide/poly (vinylidene fluoride) composite

    Tian, Pengfei; Lyu, Jun; Huang, Rui; Zhang, Chaoliang

    2017-12-01

    Piezoelectric one- (1D) and three-dimensional (3D) hybrid micro/nanostructured materials have received intense research interest because of their ability in capturing trace amounts of energy and transforming it into electrical energy. In this work, a size-distributed graphene oxide (GO) was utilized for the concurrent growth of both the 1D nanowires and 3D micro/nanowire architectures of poly (vinylidene fluoride) (PVDF) with piezoelectricity. The in situ formation of the polymeric micro/nanostructures, with crystalline beta phase, was achieved by the high-pressure crystallization of a well dispersed GO/PVDF composite, fabricated by an environmentally friendly physical approach. Particularly, by controlling the crystallization conditions of the binary composite at high pressure, the melting point of the polymeric micro/nanowires, which further constructed the 3D micro/nanoarchitectures, was nearly 30°C higher than that of the original PVDF. The large scale simultaneous formation of the 1D and 3D micro/nanostructures was attributed to a size-dependent catalysis of the GOs in the pressure-treated composite system. The as-fabricated heat-resistant hybrid micro/nanoarchitectures, consisting of GOs and piezoelectric PVDF micro/nanowires, may permit niche applications in self-powered micro/nanodevices for energy scavenging from their working environments.

  17. Quantum transport in semiconductor nanowires

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS)

  18. Radiation effects in bulk and nanostructured silicon

    Holmstrom, E.

    2012-07-01

    Understanding radiation effects in silicon (Si) is of great technological importance. The material, being the basis of modern semiconductor electronics and photonics, is subjected to radiation already at the processing stage, and in many applications throughout the lifetime of the manufactured component. Despite decades of research, many fundamental questions on the subject are still not satisfactorily answered, and new ones arise constantly as device fabrication shifts towards the nanoscale. In this study, methods of computational physics are harnessed to tackle basic questions on the radiation response of bulk and nanostructured Si systems, as well as to explain atomic-scale phenomena underlying existing experimental results. Empirical potentials and quantum mechanical models are coupled with molecular dynamics simulations to model the response of Si to irradiation and to characterize the created crystal damage. The threshold displacement energy, i.e., the smallest recoil energy required to create a lattice defect, is determined in Si bulk and nanowires, in the latter system also as a function of mechanical strain. It is found that commonly used values for this quantity are drastically underestimated. Strain on the nanowire causes the threshold energy to drop, with an effect on defect production that is significantly higher than in an another nanostructure with similar dimensions, the carbon nanotube. Simulating ion irradiation of Si nanowires reveals that the large surface area to volume ratio of the nanostructure causes up to a three-fold enhancement in defect production as compared to bulk Si. Amorphous defect clusters created by energetic neutron bombardment are predicted, on the basis of their electronic structure and abundance, to cause a deleterious phenomenon called type inversion in Si strip detectors in high-energy physics experiments. The thinning of Si lamellae using a focused ion beam is studied in conjunction with experiment to unravel the cause for

  19. In situ TEM electromechanical testing of nanowires and nanotubes.

    Espinosa, Horacio D; Bernal, Rodrigo A; Filleter, Tobin

    2012-11-05

    The emergence of one-dimensional nanostructures as fundamental constituents of advanced materials and next-generation electronic and electromechanical devices has increased the need for their atomic-scale characterization. Given its spatial and temporal resolution, coupled with analytical capabilities, transmission electron microscopy (TEM) has been the technique of choice in performing atomic structure and defect characterization. A number of approaches have been recently developed to combine these capabilities with in-situ mechanical deformation and electrical characterization in the emerging field of in-situ TEM electromechanical testing. This has enabled researchers to establish unambiguous synthesis-structure-property relations for one-dimensional nanostructures. In this article, the development and latest advances of several in-situ TEM techniques to carry out mechanical and electromechanical testing of nanowires and nanotubes are reviewed. Through discussion of specific examples, it is shown how the merging of several microsystems and TEM has led to significant insights into the behavior of nanowires and nanotubes, underscoring the significant role in-situ techniques play in the development of novel nanoscale systems and materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Organic nanowire hierarchy over fabric platform for flexible cold cathode

    Maiti, Soumen; Narayan Maiti, Uday; Pal, Shreyasi; Chattopadhyay, Kalyan Kumar

    2013-11-01

    Organic charge transfer (CT) complexes initiated a growing interest in modern electronic devices owing to their easy processability and unique characteristics. In this work, three-dimensional field emitters comprising metal-organic charge transfer complex nanostructures of AgTCNQ and CuTCNQ (TCNQ, 7,7,8,8-tetracyanoquinodimethane) over flexible fabric substrate are realized. Deliberate control over the reaction parameter during organic solid phase reaction leads to modification in structural parameters of the nanowires (i.e. length, diameter) as well as their arrangement atop the carbon fibers. The optimized arrays of AgTCNQ and CuTCNQ nanowires exhibit excellent field electron emission performance with very low turn-on (1.72 and 2.56 V μm-1) and threshold fields (4.21 and 6.33 V μm-1) respectively, which are comparable to those of the best organic field emitters reported to date. The underlying conducting carbon cloth with special woven-like geometry not only offers a flexible platform for nanowire growth, but also provides an additional field enhancement to ease the electron emission.

  1. Organic nanowire hierarchy over fabric platform for flexible cold cathode

    Maiti, Soumen; Pal, Shreyasi; Chattopadhyay, Kalyan Kumar; Maiti, Uday Narayan

    2013-01-01

    Organic charge transfer (CT) complexes initiated a growing interest in modern electronic devices owing to their easy processability and unique characteristics. In this work, three-dimensional field emitters comprising metal–organic charge transfer complex nanostructures of AgTCNQ and CuTCNQ (TCNQ, 7,7,8,8-tetracyanoquinodimethane) over flexible fabric substrate are realized. Deliberate control over the reaction parameter during organic solid phase reaction leads to modification in structural parameters of the nanowires (i.e. length, diameter) as well as their arrangement atop the carbon fibers. The optimized arrays of AgTCNQ and CuTCNQ nanowires exhibit excellent field electron emission performance with very low turn-on (1.72 and 2.56 V μm −1 ) and threshold fields (4.21 and 6.33 V μm −1 ) respectively, which are comparable to those of the best organic field emitters reported to date. The underlying conducting carbon cloth with special woven-like geometry not only offers a flexible platform for nanowire growth, but also provides an additional field enhancement to ease the electron emission. (paper)

  2. Ballistic Spin Field Effect Transistor Based on Silicon Nanowires

    Osintsev, Dmitri; Sverdlov, Viktor; Stanojevic, Zlatan; Selberherr, Siegfried

    2011-03-01

    We investigate the properties of ballistic spin field-effect transistors build on silicon nanowires. An accurate description of the conduction band based on the k . p} model is necessary in thin and narrow silicon nanostructures. The subband effective mass and subband splitting dependence on the nanowire dimensions is analyzed and used in the transport calculations. The spin transistor is formed by sandwiching the nanowire between two ferromagnetic metallic contacts. Delta-function barriers at the interfaces between the contacts and the silicon channel are introduced. The major contribution to the electric field-dependent spin-orbit interaction in confined silicon systems is due to the interface-induced inversion asymmetry which is of the Dresselhaus type. We study the current and conductance through the system for the contacts being in parallel and anti-parallel configurations. Differences between the [100] and [110] orientated structures are investigated in details. This work is supported by the European Research Council through the grant #247056 MOSILSPIN.

  3. Nanojoining of crossed Ag nanowires: a molecular dynamics study

    Cui, Jianlei, E-mail: cjlxjtu@mail.xjtu.edu.cn; Wang, Xuewen; Barayavuga, Theogene; Mei, Xuesong; Wang, Wenjun [Xi’an Jiaotong University, State Key Laboratory for Manufacturing Systems Engineering (China); He, Xiaoqiao, E-mail: bcxqhe@cityu.edu.hk [City University of Hong Kong, Department of Architecture and Civil Engineering (Hong Kong)

    2016-07-15

    Ag nanowires are considered to be the promising candidates for future electronic circuit owing to the excellent electrical and thermal properties, with the miniaturization of electronics devices into nanometer scale. Though interconnect technology between Ag nanowires (Ag NWs) is essential for nanofunctional devices, it lacks sufficient experimental data. Besides, the determination of Ag NW interconnection configuration is experimentally difficult to do for lacking the sufficient investigation of atomic configuration evolution during nanojoining process. So the nanojoining between the crossed Ag NWs with the same diameter of 2 nm and different lengths was performed by molecular dynamics simulation to explain the unclear nanojoining mechanism based on thermal effect. As the simulation results present, when the nanojoining temperature is relatively high, though the Ag NWs are connected with the interpenetration effect of Ag atoms at the crossed nanojunction area, the nanostructures of Ag NWs have been seriously deformed with shorter length and larger diameter, showing relatively more obvious melting characteristics based on the chaotic atomic structures. If the temperature is reduced to 300 K as cold welding, the crossed Ag NWs can be partially contacted with the partial mixture of Ag atoms, and the interstices always exist between the Si surface and the upper Ag nanowire. In addition, the obvious dislocation phenomenon will appear and evolve as time goes on. Consequently, the dominant mechanism was revealed for providing a fundamental understanding of how ‘hot’ and ‘cold’ welding technology affects the atomic contact configuration, respectively.

  4. Cytotoxic Effects of Nickel Nanowires in Human Fibroblasts

    Felix Servin, Laura P.

    2014-04-01

    There is an increasing interest for the use of nanostructures as potential tools in areas that include biology and medicine, for applications spanning from cell separation to treatments of diseases. Magnetic nanoparticles (MNPs) have been the most widely studied and utilized nanostructures in biomedical applications. Despite their popularity, the regular shape of MNPs limits their potential for certain applications. Studies have shown that magnetic nanowires (MNWs), due to their high-­‐aspect ratio and specific magnetic properties, might provide improved performance for some biomedical applications. As a consequence, MNWs have received increasing attention from researchers in the last years. However, as with any other nanostructure intended for biomedical applications, rigorous studies must be carried out to determine their potential toxicity and adverse effects before they can be successfully incorporated in clinical applications. This work attempts to elucidate the cytotoxic effects of nickel NWs (Ni NWs) in human fibroblasts by measuring cell viability under different parameters. Ni NWs of three different lengths (0.86 ± 0.02 μm, 1.1 ± 0.1 μm and 6.1 ± 0.6 μm) were fabricated by electrodeposition using porous aluminum oxide (PAO) membranes as templates. Energy dispersive X-­‐Ray analysis (EDAX) and X-­‐Ray diffraction (XRD) were used for the chemical characterization of the Ni NWs. Their physical characterization was done using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging. MTT assays were performed to assess cell viability of human fibroblasts in the presence of Ni NWs. NW length, NW/cell ratio and exposure time were changed throughout the experiments to elucidate their effects on cell viability. The results showed that NWs length has a strong effect on internalization and cytotoxicity. Smaller NWs showed higher toxicity levels at earlier times while longer NWs had stronger effects on cell viability at

  5. Cytotoxic Effects of Nickel Nanowires in Human Fibroblasts

    Felix Servin, Laura P.

    2014-01-01

    There is an increasing interest for the use of nanostructures as potential tools in areas that include biology and medicine, for applications spanning from cell separation to treatments of diseases. Magnetic nanoparticles (MNPs) have been the most widely studied and utilized nanostructures in biomedical applications. Despite their popularity, the regular shape of MNPs limits their potential for certain applications. Studies have shown that magnetic nanowires (MNWs), due to their high-­‐aspect ratio and specific magnetic properties, might provide improved performance for some biomedical applications. As a consequence, MNWs have received increasing attention from researchers in the last years. However, as with any other nanostructure intended for biomedical applications, rigorous studies must be carried out to determine their potential toxicity and adverse effects before they can be successfully incorporated in clinical applications. This work attempts to elucidate the cytotoxic effects of nickel NWs (Ni NWs) in human fibroblasts by measuring cell viability under different parameters. Ni NWs of three different lengths (0.86 ± 0.02 μm, 1.1 ± 0.1 μm and 6.1 ± 0.6 μm) were fabricated by electrodeposition using porous aluminum oxide (PAO) membranes as templates. Energy dispersive X-­‐Ray analysis (EDAX) and X-­‐Ray diffraction (XRD) were used for the chemical characterization of the Ni NWs. Their physical characterization was done using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging. MTT assays were performed to assess cell viability of human fibroblasts in the presence of Ni NWs. NW length, NW/cell ratio and exposure time were changed throughout the experiments to elucidate their effects on cell viability. The results showed that NWs length has a strong effect on internalization and cytotoxicity. Smaller NWs showed higher toxicity levels at earlier times while longer NWs had stronger effects on cell viability at

  6. Electronic transport in narrow-gap semiconductor nanowires

    Bloemers, Christian

    2012-10-19

    Throughout this work the electronic transport properties of InAs, InN, and GaAs/InAs core/shell nanowires have been analyzed. This includes the analysis of specific resistivity at room temperature and low temperatures as well as the breakdown of resistivity by a contribution of mobility and carrier concentration using gate measurements. While the InN nanowires showed homogeneous transport properties, there was a large statistical spread in the properties of InAs nanowires. Differing crystal structures and the surface conditions are identified to be the main reasons for the statistical spread. Both quantities of influence have been pointed out by comparing the transport parameters before and after a surface treatment (electron irradiation and long time ambient air exposure), and by comparing the transport parameters of wires grown by different growth methods which exhibit different kinds of crystal structure. In particular, the temperature dependence of the conductivity revealed different activation energies in nanowires with differing crystal structures. An explanation has been suggested in terms of stacking fault induced potential barriers. A field-effect measurement setup has been utilized to determine the nanowire mobility and carrier concentration. Even though this method is widely used for nanowires, it is subject to a serious disadvantage concerning the influence of surface and interface states on the measurements. As an alternative method which does not suffer from this drawback, Hall measurements have been successfully performed on InAs nanowires for the first time. These measurements became possible because of the utilization of a new electron beam lithographic procedure with an alignment accuracy in the 5 nm range. Carrier concentration values could be determined and compared to the ones obtained from conventional field-effect measurements. The results of the Hall measurements revealed a methodical overestimation of the carrier concentrations obtained

  7. Electronic transport in narrow-gap semiconductor nanowires

    Bloemers, Christian

    2012-01-01

    Throughout this work the electronic transport properties of InAs, InN, and GaAs/InAs core/shell nanowires have been analyzed. This includes the analysis of specific resistivity at room temperature and low temperatures as well as the breakdown of resistivity by a contribution of mobility and carrier concentration using gate measurements. While the InN nanowires showed homogeneous transport properties, there was a large statistical spread in the properties of InAs nanowires. Differing crystal structures and the surface conditions are identified to be the main reasons for the statistical spread. Both quantities of influence have been pointed out by comparing the transport parameters before and after a surface treatment (electron irradiation and long time ambient air exposure), and by comparing the transport parameters of wires grown by different growth methods which exhibit different kinds of crystal structure. In particular, the temperature dependence of the conductivity revealed different activation energies in nanowires with differing crystal structures. An explanation has been suggested in terms of stacking fault induced potential barriers. A field-effect measurement setup has been utilized to determine the nanowire mobility and carrier concentration. Even though this method is widely used for nanowires, it is subject to a serious disadvantage concerning the influence of surface and interface states on the measurements. As an alternative method which does not suffer from this drawback, Hall measurements have been successfully performed on InAs nanowires for the first time. These measurements became possible because of the utilization of a new electron beam lithographic procedure with an alignment accuracy in the 5 nm range. Carrier concentration values could be determined and compared to the ones obtained from conventional field-effect measurements. The results of the Hall measurements revealed a methodical overestimation of the carrier concentrations obtained

  8. In situ controlled synthesis of various TiO2 nanostructured materials via a facile hydrothermal route

    Wang Hai; Liu Yong; Zhong Minyi; Xu Hongmei; Huang Hong; Shen Hui

    2011-01-01

    Various TiO 2 nanomaterials, such as nanosheets, nanoflowers, and nanowires were directly self assembled on titanium substrate on a large scale under hydrothermal conditions. The morphology of the formed TiO 2 nanomaterials could be easily tuned by varying the experimental parameters of temperature, reaction time, and the NaOH concentration. A possible formation mechanism was suggested on the basis of the shape evolution of TiO 2 nanostructures by SEM images in combination with XRD patterns of as-grown samples. The optical properties of TiO 2 nanosheets, nanoflowers, and nanowires were characterized by reflectance spectroscopy. The studies revealed that the absorption capability of visible light is obviously different for TiO 2 with different morphologies. Moreover, TiO 2 nanosheets exhibited better light trapping than TiO 2 nanoflowers and TiO 2 nanowires due to their unique nanostructure.

  9. PREFACE: Self-organized nanostructures

    Rousset, Sylvie; Ortega, Enrique

    2006-04-01

    In order to fabricate ordered arrays of nanostructures, two different strategies might be considered. The `top-down' approach consists of pushing the limit of lithography techniques down to the nanometre scale. However, beyond 10 nm lithography techniques will inevitably face major intrinsic limitations. An alternative method for elaborating ultimate-size nanostructures is based on the reverse `bottom-up' approach, i.e. building up nanostructures (and eventually assemble them to form functional circuits) from individual atoms or molecules. Scanning probe microscopies, including scanning tunnelling microscopy (STM) invented in 1982, have made it possible to create (and visualize) individual structures atom by atom. However, such individual atomic manipulation is not suitable for industrial applications. Self-assembly or self-organization of nanostructures on solid surfaces is a bottom-up approach that allows one to fabricate and assemble nanostructure arrays in a one-step process. For applications, such as high density magnetic storage, self-assembly appears to be the simplest alternative to lithography for massive, parallel fabrication of nanostructure arrays with regular sizes and spacings. These are also necessary for investigating the physical properties of individual nanostructures by means of averaging techniques, i.e. all those using light or particle beams. The state-of-the-art and the current developments in the field of self-organization and physical properties of assembled nanostructures are reviewed in this issue of Journal of Physics: Condensed Matter. The papers have been selected from among the invited and oral presentations of the recent summer workshop held in Cargese (Corsica, France, 17-23 July 2005). All authors are world-renowned in the field. The workshop has been funded by the Marie Curie Actions: Marie Curie Conferences and Training Courses series named `NanosciencesTech' supported by the VI Framework Programme of the European Community, by

  10. Nanowire field effect transistors principles and applications

    Jeong, Yoon-Ha

    2014-01-01

    Nanowire Field Effect Transistor: Basic Principles and Applications” places an emphasis on the application aspects of nanowire field effect transistors (NWFET). Device physics and electronics are discussed in a compact manner, together with the p-n junction diode and MOSFET, the former as an essential element in NWFET and the latter as a general background of the FET. During this discussion, the photo-diode, solar cell, LED, LD, DRAM, flash EEPROM and sensors are highlighted to pave the way for similar applications of NWFET. Modeling is discussed in close analogy and comparison with MOSFETs. Contributors focus on processing, electrostatic discharge (ESD) and application of NWFET. This includes coverage of solar and memory cells, biological and chemical sensors, displays and atomic scale light emitting diodes. Appropriate for scientists and engineers interested in acquiring a working knowledge of NWFET as well as graduate students specializing in this subject.

  11. Superwetting nanowire membranes for selective absorption.

    Yuan, Jikang; Liu, Xiaogang; Akbulut, Ozge; Hu, Junqing; Suib, Steven L; Kong, Jing; Stellacci, Francesco

    2008-06-01

    The construction of nanoporous membranes is of great technological importance for various applications, including catalyst supports, filters for biomolecule purification, environmental remediation and seawater desalination. A major challenge is the scalable fabrication of membranes with the desirable combination of good thermal stability, high selectivity and excellent recyclability. Here we present a self-assembly method for constructing thermally stable, free-standing nanowire membranes that exhibit controlled wetting behaviour ranging from superhydrophilic to superhydrophobic. These membranes can selectively absorb oils up to 20 times the material's weight in preference to water, through a combination of superhydrophobicity and capillary action. Moreover, the nanowires that form the membrane structure can be re-suspended in solutions and subsequently re-form the original paper-like morphology over many cycles. Our results suggest an innovative material that should find practical applications in the removal of organics, particularly in the field of oil spill cleanup.

  12. Engineering Nano-Structured Multiferroic Thin Films

    Cheung, Pui Lam

    Multiferroics exhibit remarkable tunabilities in their ferromagnetic, ferroelectric and magnetoelectric properties that provide the potential in enabling the control of magnetizations by electric field for the next generation non-volatile memories, antennas and motors. In recent research and developments in integrating single-phase ferroelectric and ferromagnetic materials, multiferroic composite demonstrated a promising magnetoelectric (ME) coupling for future applications. Atomic layer deposition (ALD) technique, on the other hand, allows fabrications of complex multiferroic nanostructures to investigate interfacial coupling between the two materials. In this work, radical-enhanced ALD of cobalt ferrite (CFO) and thermal ALD of lead zirconate titanate (PZT) were combined in fabricating complex multiferroic architectures in investigating the effect of nanostructuring and magnetic shape anisotropy on improving ME coupling. In particular, 1D CFO nanotubes and nanowires; 0D-3D CFO/PZT mesoporous composite; and 1D-1D CFO/PZT core-shell nanowire composite were studied. The potential implementation of nanostructured multiferroic composites into functioning devices was assessed by quantifying the converse ME coupling coefficient. The synthesis of 1D CFO nanostructures was realized by ALD of CFO in anodic aluminum oxide (AAO) membranes. This work provided a simple and inexpensive route to create parallel and high aspect ratio ( 55) magnetic nanostructures. The change in magnetic easy axis of (partially filled) CFO nanotubes from perpendicular to parallel in (fully-filled) nanowires indicated the significance of the geometric factor in controlling magnetizations and ME coupling. The 0D-3D CFO/PZT mesoporous composite demonstrated the optimizations of the strain transfer could be achieved by precise thickness control. 100 nm of mesoporous PZT was synthesized on Pt/TiOx/SiO2/Si using amphiphilic diblock copolymers as a porous ferroelectric template (10 nm pore diameter) for

  13. The prevalent synthesis of one-dimensional noble metal nanostructures based on sulfonated polyaniline at room temperature

    Xia Youyi

    2011-01-01

    We describe a prevalent method of synthesizing one-dimensional (1D) noble metal nanostructures (silver nanobelts and palladium nanowires) by treatment of corresponding noble metal ions only in the presence of the conductive sulfonated polyaniline without using any other reducing agents or energies. The results show that the sulfonated polyaniline provides the dual reductant and “soft template” roles to promoting noble metal ions to form shape-controlled 1D noble metal nanostructures in high yield. The employed approach may also shed some light on the preparation of other noble metal nanostructure by using conductive polymer.

  14. Indium antimonide nanowires arrays for promising thermoelectric converters

    Gorokh G. G.

    2015-02-01

    Full Text Available The authors have theoretically substantiated the possibility to create promising thermoelectric converters based on quantum wires. The calculations have shown that the use of quantum wires with lateral dimensions smaller than quantum confinement values and high concentration and mobility of electrons, can lead to a substantial cooling of one of the contacts up to tens of degrees and to the heating of the other. The technological methods of manufacturing of indium antimonide nanowires arrays with high aspect ratio of the nanowire diameters to their length in the modified nanoporous anodic alumina matrixes were developed and tested. The microstructure and composition of the formed nanostructures were investigated. The electron microscopy allowed establishing that within each pore nanowires are formed with diameters of 35 nm and a length of 35 microns (equal to the matrix thickness. The electron probe x-ray microanalysis has shown that the atomic ratio of indium and antimony in the semiconductor nanostructures amounted to 38,26% and 61,74%, respectively. The current-voltage measurement between the upper and lower contacts of Cu/InSb/Cu structure (1 mm2 has shown that at 2.82 V negative voltage at the emitter contact, current density is 129,8 A/cм2, and the collector contact is heated up to 75 degrees during 150 sec. Thus, the experimental results confirmed the theoretical findings that the quantum wire systems can be used to create thermoelectric devices, which can be widely applied in electronics, in particular, for cooling integrated circuits (processors, thermal controlling of the electrical circuits by changing voltage value.

  15. Fabrication and characterization of active nanostructures

    Opondo, Noah F.

    Three different nanostructure active devices have been designed, fabricated and characterized. Junctionless transistors based on highly-doped silicon nanowires fabricated using a bottom-up fabrication approach are first discussed. The fabrication avoids the ion implantation step since silicon nanowires are doped in-situ during growth. Germanium junctionless transistors fabricated with a top down approach starting from a germanium on insulator substrate and using a gate stack of high-k dielectrics and GeO2 are also presented. The levels and origin of low-frequency noise in junctionless transistor devices fabricated from silicon nanowires and also from GeOI devices are reported. Low-frequency noise is an indicator of the quality of the material, hence its characterization can reveal the quality and perhaps reliability of fabricated transistors. A novel method based on low-frequency noise measurement to envisage trap density in the semiconductor bandgap near the semiconductor/oxide interface of nanoscale silicon junctionless transistors (JLTs) is presented. Low-frequency noise characterization of JLTs biased in saturation is conducted at different gate biases. The noise spectrum indicates either a Lorentzian or 1/f. A simple analysis of the low-frequency noise data leads to the density of traps and their energy within the semiconductor bandgap. The level of noise in silicon JLT devices is lower than reported values on transistors fabricated using a top-down approach. This noise level can be significantly improved by improving the quality of dielectric and the channel interface. A micro-vacuum electron device based on silicon field emitters for cold cathode emission is also presented. The presented work utilizes vertical Si nanowires fabricated by means of self-assembly, standard lithography and etching techniques as field emitters in this dissertation. To obtain a high nanowire density, hence a high current density, a simple and inexpensive Langmuir Blodgett technique

  16. Perspectives: Nanofibers and nanowires for disordered photonics

    Dario Pisignano

    2017-03-01

    Full Text Available As building blocks of microscopically non-homogeneous materials, semiconductor nanowires and polymer nanofibers are emerging component materials for disordered photonics, with unique properties of light emission and scattering. Effects found in assemblies of nanowires and nanofibers include broadband reflection, significant localization of light, strong and collective multiple scattering, enhanced absorption of incident photons, synergistic effects with plasmonic particles, and random lasing. We highlight recent related discoveries, with a focus on material aspects. The control of spatial correlations in complex assemblies during deposition, the coupling of modes with efficient transmission channels provided by nanofiber waveguides, and the embedment of random architectures into individually coded nanowires will allow the potential of these photonic materials to be fully exploited, unconventional physics to be highlighted, and next-generation optical devices to be achieved. The prospects opened by this technology include enhanced random lasing and mode-locking, multi-directionally guided coupling to sensors and receivers, and low-cost encrypting miniatures for encoders and labels.

  17. Characterization of silver-gallium nanowires for force and mass sensing applications

    Biedermann, Laura B; Reifenberger, Ronald G; Tung, Ryan C; Raman, Arvind; Yazdanpanah, Mehdi M; Cohn, Robert W

    2010-01-01

    We investigate the mechanical properties of cantilevered silver-gallium (Ag 2 Ga) nanowires using laser Doppler vibrometry. From measurements of the resonant frequencies and associated operating deflection shapes, we demonstrate that these Ag 2 Ga nanowires behave as ideal Euler-Bernoulli beams. Furthermore, radial asymmetries in these nanowires are detected through high resolution measurements of the vibration spectra. These crystalline nanowires possess many ideal characteristics for nanoscale force and mass sensing, including small spring constants (as low as 10 -4 N m -1 ), high frequency bandwidth with resonance frequencies in the 0.02-10 MHz range, small suspended mass (picograms), and relatively high Q-factors (∼2-50) under ambient conditions. We evaluate the utility of Ag 2 Ga nanowires for nanocantilever applications, including ultrasmall mass and high frequency bandwidth piconewton force detection.

  18. Probing plasmonic nanostructures by photons and electrons

    Kneipp, Katrin; Kneipp, Harald; Kneipp, Janina

    2015-01-01

    We discuss recent developments for studying plasmonic metal nanostructures. Exploiting photons and electrons opens up new capabilities to probe the complete plasmon spectrum including bright and dark modes and related local optical fields at subnanometer spatial resolution. This comprehensive cha...

  19. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    Aravindh, S. Assa; Schwingenschloegl, Udo, E-mail: udo.schwingenschloegl@kaust.edu.sa, E-mail: iman.roqan@kaust.edu.sa; Roqan, Iman S., E-mail: udo.schwingenschloegl@kaust.edu.sa, E-mail: iman.roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia)

    2014-12-21

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn{sub 48}O{sub 48} nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high T{sub C} in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  20. BiOCl nanowire with hierarchical structure and its Raman features

    Tian Ye; Guo Chuanfei; Guo Yanjun; Wang Qi; Liu Qian

    2012-01-01

    BiOCl is a promising V-VI-VII-compound semiconductor with excellent optical and electrical properties, and has great potential applications in photo-catalysis, photoelectric, etc. We successfully synthesize BiOCl nanowire with a hierarchical structure by combining wet etch (top-down) with liquid phase crystal growth (bottom-up) process, opening a novel method to construct ordered bismuth-based nanostructures. The morphology and lattice structures of Bi nanowires, β-Bi 2 O 3 nanowires and BiOCl nanowires with the hierarchical structure are investigated by scanning electron microscope (SEM) and transition electron microscope (TEM). The formation mechanism of such ordered BiOCl hierarchical structure is considered to mainly originate from the highly preferred growth, which is governed by the lattice match between (1 1 0) facet of BiOCl and (2 2 0) or (0 0 2) facet of β-Bi 2 O 3 . A schematic model is also illustrated to depict the formation process of the ordered BiOCl hierarchical structure. In addition, Raman properties of the BiOCl nanowire with the hierarchical structure are investigated deeply.

  1. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    Aravindh, S. Assa

    2014-12-19

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48O48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high TC in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  2. Influence of the Hydrothermal Method Growth Parameters on the Zinc Oxide Nanowires Deposited on Several Substrates

    Concepción Mejía-García

    2014-01-01

    Full Text Available We report the synthesis of ZnO nanowires grown on several substrates (PET, glass, and Si using a two-step process: (a preparation of the seed layer on the substrate by spin coating, from solutions of zinc acetate dihydrate and 1-propanol, and (b growth of the ZnO nanostructures by dipping the substrate in an equimolar solution of zinc nitrate hexahydrate and hexamethylenetetramine. Subsequently, films were thermally treated with a commercial microwave oven (350 and 700 W for 5, 20, and 35 min. The ZnO nanowires obtained were characterized structurally, morphologically, and optically using XRD, SEM, and UV-VIS transmission, respectively. XRD patterns spectra revealed the presence of Zn(OH2 on the films grown on glass and Si substrates. A preferential orientation along c-axis directions for films grown on PET substrate was observed. An analysis by SEM revealed that the growth of the ZnO nanowires on PET and glass is better than the growth on Si when the same growth parameters are used. On glass substrates, ZnO nanowires less than 50 nm in diameter and between 200 nm and 1200 nm in length were obtained. The ZnO nanowires band gap energy for the films grown on PET and glass was obtained from optical transmission spectra.

  3. Semimetal-semiconductor transitions in bismuth-antimony films and nanowires induced by size quantization

    Nikolaeva, A.A.; Konopko, L.A.; Grabov, V.M.; Komarov, V.A.; Kablukova, N.; Popov, I.A.

    2013-01-01

    Full text:Single-crystal bismuth films and nanowires undergo a transformation from semimetal to semiconductor (SMSC) thanks to the manifestation of quantum size effects, which modify phonon transport, which may be of practical interest. This effect must be most pronounced in single Bi 1-x Sb x nanostructures in the semimetal phase(x < 0.04) with a minimal overlapping of L and T bands. In this paper we present the experimental results an investigation of the low- temperature electrical transport, thermoelectrical properties, SdH oscillations of BiSb films, grown by vacuum thermal evaporation and nanowires prepared by a modified Ulitovsky - Teilor technique. We confirmed with X-ray diffraction that the trigonal axis were perpendicular to the film plane. The single Bi-2at% Sb nanowires with diameter 100-1000nm were represented single crystals in glass capillary with (1011) orientation along the wire axis. The investigations the Shubnikov de Haas oscillations shows, that overlapping L and-T- bands was in two time smaller, than in pure Bi. The quantum dimensional effect induced SMSC transition is observed in Bi-Sb films and nanowires at the wires diameters up to five times greater, than in pure Bi. That experimental fact on the one site will be allow to go at higher temperatures with the same diameters nanowires, and on the other hand allows to separate effects connected with surface state and QSE. We also discuss the thermoelectric properties for optimizing their performance for certain, such as thermoelectrics.

  4. Selective growth of silica nanowires using an Au catalyst for optical recognition of interleukin-10

    Sekhar, Praveen K; Ramgir, Niranjan S; Joshi, Rakesh K; Bhansali, Shekhar [Bio-MEMS and Microfabrication Laboratory, Department of Electrical Engineering, University of South Florida, 4202 E Fowler Avenue, ENB 118, Tampa, FL 33620 (United States)], E-mail: bhansali@eng.usf.edu

    2008-06-18

    The vapor-liquid-solid (VLS) growth procedure has been extended for the selective growth of silica nanowires on SiO{sub 2} layer by using Au as a catalyst. The nanowires were grown in an open tube furnace at 1100 deg. C for 60 min using Ar as a carrier gas. The average diameter of these bottom-up nucleated wires was found to be 200 nm. Transmission electron microscopy analysis indicates the amorphous nature of these nanoscale wires and suggests an Si-silica heterostructure. The localized silica nanowires have been used as an immunoassay template in the detection of interleukin-10 which is a lung cancer biomarker. Such a nanostructured platform offered a tenfold enhancement in the optical response, aiding the recognition of IL-10 in comparison to a bare silica substrate. The role of nanowires in the immunoassay was verified through the quenching behavior in the photoluminescence (PL) spectra. Two orders of reduction in PL intensity have been observed after completion of the immunoassay with significant quenching after executing every step of the protocol. The potential of this site-specific growth of silica nanowires on SiO{sub 2} as a multi-modal biosensing platform has been discussed.

  5. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    Aravindh, S. Assa; Schwingenschlö gl, Udo; Roqan, Iman S.

    2014-01-01

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48O48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high TC in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  6. Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

    Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

    2012-07-01

    The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm2) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

  7. Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

    Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

    2012-01-01

    The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm 2 ) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

  8. Power generation from base excitation of a Kevlar composite beam with ZnO nanowires

    Malakooti, Mohammad H.; Hwang, Hyun-Sik; Sodano, Henry A.

    2015-04-01

    One-dimensional nanostructures such as nanowires, nanorods, and nanotubes with piezoelectric properties have gained interest in the fabrication of small scale power harvesting systems. However, the practical applications of the nanoscale materials in structures with true mechanical strengths have not yet been demonstrated. In this paper, piezoelectric ZnO nanowires are integrated into the fiber reinforced polymer composites serving as an active phase to convert the induced strain energy from ambient vibration into electrical energy. Arrays of ZnO nanowires are grown vertically aligned on aramid fibers through a low-cost hydrothermal process. The modified fabrics with ZnO nanowires whiskers are then placed between two carbon fabrics as the top and the bottom electrodes. Finally, vacuum resin transfer molding technique is utilized to fabricate these multiscale composites. The fabricated composites are subjected to a base excitation using a shaker to generate charge due to the direct piezoelectric effect of ZnO nanowires. Measuring the generated potential difference between the two electrodes showed the energy harvesting application of these multiscale composites in addition to their superior mechanical properties. These results propose a new generation of power harvesting systems with enhanced mechanical properties.

  9. PdM (M = Pt, Au) bimetallic alloy nanowires with enhanced electrocatalytic activity for electro-oxidation of small molecules.

    Zhu, Chengzhou; Guo, Shaojun; Dong, Shaojun

    2012-05-02

    A facile and general method has been developed to synthesize well-defined PdPt and PdAu alloy nanowires, which exhibit significantly enhanced activity towards small molecules, such as ethanol, methanol, and glucose electro-oxidation in an alkaline medium. Considering the important role of one-dimensional alloy nanowires in electrocatalytic systems, the present Pd-based alloy nanostructures could offer a promising new class of advanced electrocatalysts for direct alcohol fuel cells and electrochemical sensors. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Mesoporous nickel oxide nanowires: hydrothermal synthesis, characterisation and applications for lithium-ion batteries and supercapacitors with superior performance.

    Su, Dawei; Kim, Hyun-Soo; Kim, Woo-Seong; Wang, Guoxiu

    2012-06-25

    Mesoporous nickel oxide nanowires were synthesized by a hydrothermal reaction and subsequent annealing at 400 °C. The porous one-dimensional nanostructures were analysed by field-emission SEM, high-resolution TEM and N(2) adsorption/desorption isotherm measurements. When applied as the anode material in lithium-ion batteries, the as-prepared mesoporous nickel oxide nanowires demonstrated outstanding electrochemical performance with high lithium storage capacity, satisfactory cyclability and an excellent rate capacity. They also exhibited a high specific capacitance of 348 F g(-1) as electrodes in supercapacitors. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Transparent TiO2 nanowire networks via wet corrosion of Ti thin films for dye-sensitized solar cells

    Shin, Eunhye; Jin, Saera; Hong, Jongin

    2017-09-01

    Transparent TiO2 nanowire networks were prepared by corrosion of Ti thin films on F-doped SnO2 glass substrates in an alkaline (potassium hydroxide: KOH) solution. The formation of the porous TiO2 nanostructures from the Ti thin films was thoroughly investigated. Dye-sensitized solar cells with a photoanode of 1.2-μm-thick nanowire networks exhibit an average optical transmittance of 40% in the visible light region and a power conversion efficiency of 1.0% under one sun illumination.

  12. Magnetic nanowires (Fe, Fe-Co, Fe-Ni – magnetic moment reorientation in respect of wires composition

    Kalska-Szostko Beata

    2015-03-01

    Full Text Available Magnetic nanowires of Fe, Fe-Co, and Fe-Ni alloy and layered structure were prepared by electrochemical alternating current (AC deposition method. The morphology of the nanowires in and without the matrix was studied by energy dispersive X-ray spectroscopy (EDX, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. The wires either show strong dependence on the combination of elements deposition (alloy or layered or chemical composition (Co or Ni. The magnetic properties of the nanostructures were determined on the basis of Mössbauer spectroscopy (MS.

  13. Measurement and simulation of anisotropic magnetoresistance in single GaAs/MnAs core/shell nanowires

    Liang, J.; Wang, J.; Cooley, B. J.; Rench, D. W.; Samarth, N.; Paul, A.; Dellas, N. S.; Mohney, S. E.; Engel-Herbert, R.

    2012-01-01

    We report four probe measurements of the low field magnetoresistance (MR) in single core/shell GaAs/MnAs nanowires (NWs) synthesized by molecular beam epitaxy, demonstrating clear signatures of anisotropic magnetoresistance that track the field-dependent magnetization. A comparison with micromagnetic simulations reveals that the principal characteristics of the magnetoresistance data can be unambiguously attributed to the nanowire segments with a zinc blende GaAs core. The direct correlation between magnetoresistance, magnetization, and crystal structure provides a powerful means of characterizing individual hybrid ferromagnet/semiconductor nanostructures.

  14. Passivation of ZnO Nanowire Guests and 3D Inverse Opal Host Photoanodes for Dye-Sensitized Solar Cells

    Labouchere, Philippe

    2014-04-23

    A hierarchical host-guest nanostructured photoanode is reported for dye-sensitized solar cells. It is composed of ZnO nanowires grown in situ into the macropores of a 3D ZnO inverse opal structure, which acts both as a seed layer and as a conductive backbone host. Using a combination of self-assembly, hydrothermal or electrodeposition of single crystalline ZnO nanowires and TiO2 passivation, a novel photoanode with scattering capability for optimal light harvesting is fabricated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Extraordinary Magnetic Field Enhancement with Metallic Nanowire: Role of Surface Impedance in Babinet's Principle for Sub-Skin-Depth Regime

    Koo, Sukmo; Kumar, M. Sathish; Shin, Jonghwa; Kim, Daisik; Park, Namkyoo

    2009-12-01

    We propose and analyze the “complementary” structure of a metallic nanogap, namely, the metallic nanowire for magnetic field enhancement. A huge enhancement of the field up to a factor of 300 was achieved. Introducing the surface impedance concept, we also develop and numerically confirm a new analytic theory which successfully predicts the field enhancement factors for metal nanostructures. Compared to the predictions of the classical Babinet principle applied to a nanogap, an order of magnitude difference in the field enhancement factor was observed for the sub-skin-depth regime nanowire.

  16. Architecting boron nanostructure on the diamond particle surface

    Bai, H.; Dai, D.; Yu, J.H.; Nishimura, K.; Sasaoka, S.; Jiang, N.

    2014-01-01

    The present study provides an efficient approach for nano-functionalization of diamond powders. Boron nanostructure can be grown on diamond particle entire surface by a simple heat-treatment process. After treatment, various boron nanoforms were grown on the diamond particle surface at different processing temperature. High-density boron nanowires (BNWs) grow on the diamond particle entire surface at 1333 K, while nanopillars cover diamond powders when the heat treatment process is performed at 1393 K. The influence of the pretreatment temperature on the microstructure and thermal conductivity of Cu/diamond composites were investigated. Cu/diamond composites with high thermal conductivity of 670 W (m K) −1 was obtained, which was achieved by the formation of large number of nanowires and nanopillars on the diamond particle surface.

  17. Nanostructure Engineered Chemical Sensors for Hazardous Gas and Vapor Detection

    Li, Jing; Lu, Yijiang

    2005-01-01

    A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs) and metal oxides nanowires or nanobelts, on a pair of interdigitated electrodes (IDE) processed with a silicon based microfabrication and micromachining technique. The IDE fingers were fabricated using thin film metallization techniques. Both in-situ growth of nanostructure materials and casting of the nanostructure dispersions were used to make chemical sensing devices. These sensors have been exposed to hazardous gases and vapors, such as acetone, benzene, chlorine, and ammonia in the concentration range of ppm to ppb at room temperature. The electronic molecular sensing in our sensor platform can be understood by electron modulation between the nanostructure engineered device and gas molecules. As a result of the electron modulation, the conductance of nanodevice will change. Due to the large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors potentially can offer higher sensitivity, lower power consumption and better robustness than the state-of-the-art systems, which make them more attractive for defense and space applications. Combined with MEMS technology, light weight and compact size sensors can be made in wafer scale with low cost.

  18. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    Pruna, R., E-mail: rpruna@el.ub.edu; Palacio, F.; López, M. [SIC, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain); Pérez, J. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Mir, M. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5 Pabellón 11, E-28029 Madrid (Spain); Blázquez, O.; Hernández, S.; Garrido, B. [MIND-IN" 2UB, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)

    2016-08-08

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  19. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    Pruna, R.; Palacio, F.; López, M.; Pérez, J.; Mir, M.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Blázquez, O.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Hernández, S.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Garrido, B.

    2016-01-01

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  20. Direct observation of single-charge-detection capability of nanowire field-effect transistors.

    Salfi, J; Savelyev, I G; Blumin, M; Nair, S V; Ruda, H E

    2010-10-01

    A single localized charge can quench the luminescence of a semiconductor nanowire, but relatively little is known about the effect of single charges on the conductance of the nanowire. In one-dimensional nanostructures embedded in a material with a low dielectric permittivity, the Coulomb interaction and excitonic binding energy are much larger than the corresponding values when embedded in a material with the same dielectric permittivity. The stronger Coulomb interaction is also predicted to limit the carrier mobility in nanowires. Here, we experimentally isolate and study the effect of individual localized electrons on carrier transport in InAs nanowire field-effect transistors, and extract the equivalent charge sensitivity. In the low carrier density regime, the electrostatic potential produced by one electron can create an insulating weak link in an otherwise conducting nanowire field-effect transistor, modulating its conductance by as much as 4,200% at 31 K. The equivalent charge sensitivity, 4 × 10(-5) e Hz(-1/2) at 25 K and 6 × 10(-5) e Hz(-1/2) at 198 K, is orders of magnitude better than conventional field-effect transistors and nanoelectromechanical systems, and is just a factor of 20-30 away from the record sensitivity for state-of-the-art single-electron transistors operating below 4 K (ref. 8). This work demonstrates the feasibility of nanowire-based single-electron memories and illustrates a physical process of potential relevance for high performance chemical sensors. The charge-state-detection capability we demonstrate also makes the nanowire field-effect transistor a promising host system for impurities (which may be introduced intentionally or unintentionally) with potentially long spin lifetimes, because such transistors offer more sensitive spin-to-charge conversion readout than schemes based on conventional field-effect transistors.

  1. Nanostructured surfaces investigated by quantitative morphological studies

    Perani, Martina; Carapezzi, Stefania; Mutta, Geeta Rani; Cavalcoli, Daniela

    2016-01-01

    The morphology of different surfaces has been investigated by atomic force microscopy and quantitatively analyzed in this paper. Two different tools have been employed to this scope: the analysis of the height–height correlation function and the determination of the mean grain size, which have been combined to obtain a complete characterization of the surfaces. Different materials have been analyzed: SiO_xN_y, InGaN/GaN quantum wells and Si nanowires, grown with different techniques. Notwithstanding the presence of grain-like structures on all the samples analyzed, they present very diverse surface design, underlying that this procedure can be of general use. Our results show that the quantitative analysis of nanostructured surfaces allows us to obtain interesting information, such as grain clustering, from the comparison of the lateral correlation length and the grain size. (paper)

  2. Magnetic field-assisted synthesis of wire-like Co3O4 nanostructures: Electrochemical and photocatalytic studies

    Zhao, Xiubin; Pang, Zhanwen; Wu, Mingzai; Liu, Xiansong; Zhang, Hui; Ma, Yongqing; Sun, Zhaoqi; Zhang, Lide; Chen, Xiaoshuang

    2013-01-01

    Graphical abstract: Schematic illustration for the magnetic field-assisted growth of wire-like Co 3 O 4 nanostructure. Display Omitted Highlights: ► Co 3 O 4 nanowires are prepared by magnetic field hydrothermal reduction and annealing. ► These Co 3 O 4 nanowires possess enhanced capacitance. ► The Co 3 O 4 nanowires have a good photocatalytic activity for methyl orange. -- Abstract: Wire-like Co 3 O 4 nanostructures were prepared by the combination of magnetic field-assisted hydrothermal reduction of cobalt ions and the subsequent ambient annealing at 500 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphological evolution of the products. The results show that the wire-like nanostructures possess diameters about 250 nm and lengths over 10 μm. The possible formation mechanism of the wire-like Co 3 O 4 nanostructures is also proposed based on the SEM results. Galvanostatic methods were used to characterize the electrochemical properties. The measurements indicate that the wire-like Co 3 O 4 nanostructures show larger discharge and charge capacities than that of spherical Co 3 O 4 nanoparticles prepared in the absence of magnetic field. In addition, the photocatalytic activity of the products was investigated by measuring the photodegradation of methyl orange solution under ultraviolet radiation, which shows that both the wire-like and spherical products have a good photocatalytic activity.

  3. Energy harvesting performance of piezoelectric ceramic and polymer nanowires.

    Crossley, Sam; Kar-Narayan, Sohini

    2015-08-28

    Energy harvesting from ubiquitous ambient vibrations is attractive for autonomous small-power applications and thus considerable research is focused on piezoelectric materials as they permit direct inter-conversion of mechanical and electrical energy. Nanogenerators (NGs) based on piezoelectric nanowires are particularly attractive due to their sensitivity to small-scale vibrations and may possess superior mechanical-to-electrical conversion efficiency when compared to bulk or thin-film devices of the same material. However, candidate piezoelectric nanowires have hitherto been predominantly analyzed in terms of NG output (i.e. output voltage, output current and output power density). Surprisingly, the corresponding dynamical properties of the NG, including details of how the nanowires are mechanically driven and its impact on performance, have been largely neglected. Here we investigate all realizable NG driving contexts separately involving inertial displacement, applied stress T and applied strain S, highlighting the effect of driving mechanism and frequency on NG performance in each case. We argue that, in the majority of cases, the intrinsic high resonance frequencies of piezoelectric nanowires (∼tens of MHz) present no barrier to high levels of NG performance even at frequencies far below resonance (materials properties, for comparing piezoelectric NG performance under strain-driven and stress-driven conditions respectively. These figures of merit permit, for the first time, a general comparison of piezoelectric nanowires for NG applications that takes into account the nature of the mechanical excitation. We thus investigate the energy harvesting performance of prototypical piezoelectric ceramic and polymer nanowires. We find that even though ceramic and polymer nanowires have been found, in certain cases, to have similar energy conversion efficiencies, ceramics are more promising in strain-driven NGs while polymers are more promising for stress-driven NGs

  4. Contact planarization of ensemble nanowires

    Chia, A. C. E.; LaPierre, R. R.

    2011-06-01

    The viability of four organic polymers (S1808, SC200, SU8 and Cyclotene) as filling materials to achieve planarization of ensemble nanowire arrays is reported. Analysis of the porosity, surface roughness and thermal stability of each filling material was performed. Sonication was used as an effective method to remove the tops of the nanowires (NWs) to achieve complete planarization. Ensemble nanowire devices were fully fabricated and I-V measurements confirmed that Cyclotene effectively planarizes the NWs while still serving the role as an insulating layer between the top and bottom contacts. These processes and analysis can be easily implemented into future characterization and fabrication of ensemble NWs for optoelectronic device applications.

  5. Nanostructured thin films and coatings functional properties

    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

  6. Ceramic nanostructures and methods of fabrication

    Ripley, Edward B [Knoxville, TN; Seals, Roland D [Oak Ridge, TN; Morrell, Jonathan S [Knoxville, TN

    2009-11-24

    Structures and methods for the fabrication of ceramic nanostructures. Structures include metal particles, preferably comprising copper, disposed on a ceramic substrate. The structures are heated, preferably in the presence of microwaves, to a temperature that softens the metal particles and preferably forms a pool of molten ceramic under the softened metal particle. A nano-generator is created wherein ceramic material diffuses through the molten particle and forms ceramic nanostructures on a polar site of the metal particle. The nanostructures may comprise silica, alumina, titania, or compounds or mixtures thereof.

  7. A molecular dynamics simulation study of irradiation induced defects in gold nanowire

    Liu, Wenqiang; Chen, Piheng; Qiu, Ruizhi; Khan, Maaz; Liu, Jie; Hou, Mingdong; Duan, Jinglai

    2017-08-01

    Displacement cascade in gold nanowires was studied using molecular dynamics computer simulations. Primary knock-on atoms (PKAs) with different kinetic energies were initiated either at the surface or at the center of the nanowires. We found three kinds of defects that were induced by the cascade, including point defects, stacking faults and crater at the surface. The starting points of PKAs influence the number of residual point defects, and this consequently affect the boundary of anti-radiation window which was proposed by calculation of diffusion of point defects to the free surface of nanowires. Formation of stacking faults that expanded the whole cross-section of gold nanowires was observed when the PKA's kinetic energy was higher than 5 keV. Increasing the PKA's kinetic energy up to more than 10 keV may lead to the formation of crater at the surface of nanowires due to microexplosion of hot atoms. At this energy, PKAs started from the center of nanowires can also result in the creation of crater because length of cascade region is comparable to diameter of nanowires. Both the two factors, namely initial positions of PKAs as well as the craters induced by higher energy irradiation, would influence the ability of radiation resistance of metal nanowires.

  8. Two-dimensional nanowires on homoepitaxial interfaces: Atomic-scale mechanism of breakdown and disintegration

    Michailov, Michail; Ranguelov, Bogdan

    2018-03-01

    We present a model for hole-mediated spontaneous breakdown of ahomoepitaxial two-dimensional (2D) flat nanowire based exclusively on random, thermally-activated motion of atoms. The model suggests a consecutive three-step mechanism driving the rupture and complete disintegration of the nanowire on a crystalline surface. The breakdown scenario includes: (i) local narrowing of a part of the stripe to a monatomic chain, (ii) formation of a recoverable single vacancy or a 2D vacancy cluster that causes temporary nanowire rupture, (iii) formation of a non-recoverable 2D hole leading to permanent nanowire breakdown. These successive events in the temporal evolution of the nanowire morphology bring the nanowire stripe into an irreversible unstable state, leading to a dramatic change in its peculiar physical properties and conductivity. The atomistic simulations also reveal a strong increase of the nanowire lifetime with an enlargement of its width and open up a way for a fine atomic-scale control of the nanowire lifetime and structural, morphological and thermodynamic stability.

  9. Solution-processed core-shell nanowires for efficient photovoltaic cells.

    Tang, Jinyao; Huo, Ziyang; Brittman, Sarah; Gao, Hanwei; Yang, Peidong

    2011-08-21

    Semiconductor nanowires are promising for photovoltaic applications, but, so far, nanowire-based solar cells have had lower efficiencies than planar cells made from the same materials, even allowing for the generally lower light absorption of nanowires. It is not clear, therefore, if the benefits of the nanowire structure, including better charge collection and transport and the possibility of enhanced absorption through light trapping, can outweigh the reductions in performance caused by recombination at the surface of the nanowires and at p-n junctions. Here, we fabricate core-shell nanowire solar cells with open-circuit voltage and fill factor values superior to those reported for equivalent planar cells, and an energy conversion efficiency of ∼5.4%, which is comparable to that of equivalent planar cells despite low light absorption levels. The device is made using a low-temperature solution-based cation exchange reaction that creates a heteroepitaxial junction between a single-crystalline CdS core and single-crystalline Cu2S shell. We integrate multiple cells on single nanowires in both series and parallel configurations for high output voltages and currents, respectively. The ability to produce efficient nanowire-based solar cells with a solution-based process and Earth-abundant elements could significantly reduce fabrication costs relative to existing high-temperature bulk material approaches.

  10. Nanostructures of Boron, Carbon and Magnesium Diboride for High Temperature Superconductivity

    Pfefferle, Lisa [Yale Univ., New Haven, CT (United States); Fang, Fang [Yale Univ., New Haven, CT (United States); Iyyamperumal, Eswarmoorthi [Yale Univ., New Haven, CT (United States); Keskar, Gayatri [Yale Univ., New Haven, CT (United States)

    2013-12-23

    Direct fabrication of MgxBy nanostructures is achieved by employing metal (Ni,Mg) incorporated MCM-41 in the Hybrid Physical-Chemical Vapor Deposition (HPCVD) reaction. Different reaction conditions are tested to optimize the fabrication process. TEM analysis shows the fabrication of MgxBy nanostructures starting at the reaction temperature of 600oC, with the yield of the nanostructures increasing with increasing reaction temperature. The as-synthesized MgxBy nanostructures have the diameters in the range of 3-5nm, which do not increase with the reaction temperature consistent with templated synthesis. EELS analysis of the template removed nanostructures confirms the existence of B and Mg with possible contamination of Si and O. NEXAFS and Raman spectroscopy analysis suggested a concentric layer-by-layer MgxBy nanowire/nanotube growth model for our as-synthesized nanostructures. Ni k-edge XAS indicates that the formation of MgNi alloy particles is important for the Vapor-Liquid-Solid (VLS) growth of MgxBy nanostructures with fine diameters, and the presence of Mg vapor not just Mg in the catalyst is crucial for the formation of Ni-Mg clusters. Physical templating by the MCM-41 pores was shown to confine the diameter of the nanostructures. DC magnetization measurements indicate possible superconductive behaviors in the as-synthesized samples.

  11. Numerical Modeling of the Photothermal Processing for Bubble Forming around Nanowire in a Liquid

    Anis Chaari

    2014-01-01

    Full Text Available An accurate computation of the temperature is an important factor in determining the shape of a bubble around a nanowire immersed in a liquid. The study of the physical phenomenon consists in solving a photothermic coupled problem between light and nanowire. The numerical multiphysic model is used to study the variations of the temperature and the shape of the created bubble by illumination of the nanowire. The optimization process, including an adaptive remeshing scheme, is used to solve the problem through a finite element method. The study of the shape evolution of the bubble is made taking into account the physical and geometrical parameters of the nanowire. The relation between the sizes and shapes of the bubble and nanowire is deduced.

  12. Numerical Modeling of the Photothermal Processing for Bubble Forming around Nanowire in a Liquid

    Chaari, Anis; Giraud-Moreau, Laurence

    2014-01-01

    An accurate computation of the temperature is an important factor in determining the shape of a bubble around a nanowire immersed in a liquid. The study of the physical phenomenon consists in solving a photothermic coupled problem between light and nanowire. The numerical multiphysic model is used to study the variations of the temperature and the shape of the created bubble by illumination of the nanowire. The optimization process, including an adaptive remeshing scheme, is used to solve the problem through a finite element method. The study of the shape evolution of the bubble is made taking into account the physical and geometrical parameters of the nanowire. The relation between the sizes and shapes of the bubble and nanowire is deduced. PMID:24795538

  13. Interactions between semiconductor nanowires and living cells.

    Prinz, Christelle N

    2015-06-17

    Semiconductor nanowires are increasingly used for biological applications and their small dimensions make them a promising tool for sensing and manipulating cells with minimal perturbation. In order to interface cells with nanowires in a controlled fashion, it is essential to understand the interactions between nanowires and living cells. The present paper reviews current progress in the understanding of these interactions, with knowledge gathered from studies where living cells were interfaced with vertical nanowire arrays. The effect of nanowires on cells is reported in terms of viability, cell-nanowire interface morphology, cell behavior, changes in gene expression as well as cellular stress markers. Unexplored issues and unanswered questions are discussed.

  14. Advanced Magnetic Nanostructures

    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...

  15. Nanostructured composite reinforced material

    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.

  16. Effects of piezoelectric potential on the transport characteristics of metal-ZnO nanowire-metal field effect transistor

    Gao, Zhiyuan

    2009-01-01

    We have investigated the effects of piezoelectric potential in a ZnO nanowire on the transport characteristics of the nanowire based field effect transistor through numerical calculations and experimental observations. Under different straining conditions including stretching, compressing, twisting, and their combination, a piezoelectric potential is created throughout the nanowire to modulatealternate the transport property of the metal-ZnO nanowire contacts, resulting in a switch between symmetric and asymmetric contacts at the two ends, or even turning an Ohmic contact type into a diode. The commonly observed natural rectifying behavior of the as-fabricated ZnO nanowire can be attributed to the strain that was unpurposely created in the nanowire during device fabrication and material handling. This work provides further evidence on piezopotential governed electronic transport and devices, e.g., piezotronics.

  17. Molecular beam epitaxial growth and characterization of Al(Ga)N nanowire deep ultraviolet light emitting diodes and lasers

    Mi, Z; Zhao, S; Djavid, M; Liu, X; Kang, J; Woo, S Y; Bugnet, M; Botton, G A; Kong, X; Guo, H; Ji, W; Liu, Z

    2016-01-01

    We report on the detailed molecular beam epitaxial growth and characterization of Al(Ga)N nanowire heterostructures on Si and their applications for deep ultraviolet light emitting diodes and lasers. The nanowires are formed under nitrogen-rich conditions without using any metal catalyst. Compared to conventional epilayers, Mg-dopant incorporation is significantly enhanced in nearly strain- and defect-free Al(Ga)N nanowire structures, leading to efficient p -type conduction. The resulting Al(Ga)N nanowire LEDs exhibit excellent performance, including a turn-on voltage of ∼5.5 V for an AlN nanowire LED operating at 207 nm. The design, fabrication, and performance of an electrically injected AlGaN nanowire laser operating in the UV-B band is also presented. (paper)

  18. Growth and applicability of radiation-responsive silica nanowires

    Bettge, Martin

    manganese oxide (LiMn2O4), for use as positive materials, retain their unique texture after 30 cycles, as verified by scanning and transmission electron microscopy. Some accelerated capacity fade is however observed and attributed to chemical dissolution of the oxide material. Frequency-dependent impedances of textured oxide films are lower than those for planar films. These findings suggest that thin film texturing can indeed enhance some of the material's electrochemical performance characteristics and can be applied to a wide range of materials through use of appropriate nanostructured templates. In summary, this dissertation outlines physical and chemical factors leading to the formation of free-standing and uniquely stranded nanowires. It also provides an outlook on how ion-induced nanowire bending and alignment could be exploited. Key technological advantages of the developed process are refractory nanowire growth at low substrate temperatures and the ability to form radiation-responsive nanowire arrays without the use of lithography or templates.

  19. Electrodeposition of ZnO nano-wires lattices with a controlled morphology; Electrodepot de reseaux de nanofils de ZnO a morphologie controlee

    Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C. [Centre National de la Recherche Scientifique (CNRS), Lab. de Chimie Metallurgique des Terres Rares, UPR 209, 94 - Thiais (France)

    2006-07-01

    In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO{sub 2}. Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

  20. Nanostructured Materials for Magnetoelectronics

    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.

  1. Nanostructured silver sulfide: synthesis of various forms and their application

    Sadovnikov, S. I.; Rempel, A. A.; Gusev, A. I.

    2018-04-01

    The results of experimental studies on nanostructured silver sulfide are analyzed and generalized. The influence of small particle size on nonstoichiometry of silver sulfide is discussed. Methods for the synthesis of various forms of nanostructured Ag2S including nanopowders, stable colloidal solutions, quantum dots, core–shell nanoparticles and heteronanostructures are described. The advantages and drawbacks of different synthetic procedures are analyzed. Main fields of application of nanostructured silver sulfide are considered. The bibliography includes 184 references.

  2. Injection moulding antireflective nanostructures

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

    2014-01-01

    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...

  3. Injection moulding antireflective nanostructures

    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...

  4. Electric Conductivity of Phosphorus Nanowires

    Jing-Xiang, Zhang; Hui, Li; Xue-Qing, Zhang; Kim-Meow, Liew

    2009-01-01

    We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

  5. Tunneling magnetoresistance in Si nanowires

    Montes Muñ oz, Enrique; Rungger, I.; Sanvito, S.; Schwingenschlö gl, Udo

    2016-01-01

    for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we

  6. X-ray diffraction analysis of InAs nanowires

    Davydok, Anton

    2013-01-01

    Semiconductor nanowires have attracted great interest as building blocks for future electronic and optoelectronic devices. The variability of the growth process opens the opportunity to control and combine the various properties tailoring for specific application. It was shown that the electrical and optical characteristics of the nanowires are strongly connected with their structure. Despite intensive research in this field, the growth process is still not fully understood. In particular, extensive real structure investigations are required. Most of the reports dedicated on the structural researches are based on the results of scanning electron microscopy (SEM) or transmission electron microscopy (TEM). SEM provides an image of the surface with nanostructures and is mainly used to describe the morphology of the sample, but it does not bring information about the internal structure, phase composition and defect structure. At the same time, the internal structure can be examined by TEM down to atomic scale. TEM image of good quality are very expensive due to the efforts in sample preparation and in localisation of a single object. All these aspects make the statistical structural analysis difficult. In the present work, X-ray diffraction analysis has been applied for structural investigation of InAs nanowires grown by different techniques. Using various X-ray diffraction geometries, the nanowire systems were investigated in terms of the lattice parameters, phase composition, strains and displacement fields and stacking defects. In particular, realizing grazing incidence diffraction and controlling the penetration depth of X-ray beam, we characterized sample series grown by Au-assisted metal organic phase epitaxy on GaAs [111]B substrate with different growth time. According to the results of SEM and X-ray investigations, a model of the growth process has been proposed. A more detailed analysis was performed on InAs nanowires grown by molecular beam epitaxy (MBE) on

  7. Fabrication and simulation of single crystal p-type Si nanowire using SOI technology

    Dehzangi, Arash; Larki, Farhad; Naseri, Mahmud G.; Navasery, Manizheh; Majlis, Burhanuddin Y.; Razip Wee, Mohd F.; Halimah, M.K.; Islam, Md. Shabiul; Md Ali, Sawal H.; Saion, Elias

    2015-01-01

    Highlights: • Single crystal silicon nanowire is fabricated on Si on insulator substrate, using atomic force microscope (AFM) nanolithography and KOH + IPA chemical wet etching. • Some of major parameters in fabrication process, such as writing speed and applied voltage along with KOH etching depth are investigated, and then the I–V characteristic of Si nanowires is measured. • For better understanding of the charge transmission through the nanowire, 3D-TCAD simulation is performed to simulate the Si nanowires with the same size of the fabricated ones, and variation of majority and minority carriers, hole quasi-Fermi level and generation/recombination rate are investigated. - Abstract: Si nanowires (SiNWs) as building blocks for nanostructured materials and nanoelectronics have attracted much attention due to their major role in device fabrication. In the present work a top-down fabrication approach as atomic force microscope (AFM) nanolithography was performed on Si on insulator (SOI) substrate to fabricate a single crystal p-type SiNW. To draw oxide patterns on top of the SOI substrate local anodic oxidation was carried out by AFM in contact mode. After the oxidation procedure, an optimized solution of 30 wt.% KOH with 10 vol.% IPA for wet etching at 63 °C was applied to extract the nanostructure. The fabricated SiNW had 70–85 nm full width at half maximum width, 90 nm thickness and 4 μm length. The SiNW was simulated using Sentaurus 3D software with the exact same size of the fabricated device. I–V characterization of the SiNW was measured and compared with simulation results. Using simulation results variation of carrier's concentrations, valence band edge energy and recombination generation rate for different applied voltage were investigated

  8. Fabrication and simulation of single crystal p-type Si nanowire using SOI technology

    Dehzangi, Arash, E-mail: arashd53@hotmail.com [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Larki, Farhad [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Naseri, Mahmud G. [Department of Physics, Faculty of Science, Malayer University, Malayer, Hamedan (Iran, Islamic Republic of); Navasery, Manizheh [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Majlis, Burhanuddin Y.; Razip Wee, Mohd F. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Halimah, M.K. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Islam, Md. Shabiul; Md Ali, Sawal H. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Saion, Elias [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2015-04-15

    Highlights: • Single crystal silicon nanowire is fabricated on Si on insulator substrate, using atomic force microscope (AFM) nanolithography and KOH + IPA chemical wet etching. • Some of major parameters in fabrication process, such as writing speed and applied voltage along with KOH etching depth are investigated, and then the I–V characteristic of Si nanowires is measured. • For better understanding of the charge transmission through the nanowire, 3D-TCAD simulation is performed to simulate the Si nanowires with the same size of the fabricated ones, and variation of majority and minority carriers, hole quasi-Fermi level and generation/recombination rate are investigated. - Abstract: Si nanowires (SiNWs) as building blocks for nanostructured materials and nanoelectronics have attracted much attention due to their major role in device fabrication. In the present work a top-down fabrication approach as atomic force microscope (AFM) nanolithography was performed on Si on insulator (SOI) substrate to fabricate a single crystal p-type SiNW. To draw oxide patterns on top of the SOI substrate local anodic oxidation was carried out by AFM in contact mode. After the oxidation procedure, an optimized solution of 30 wt.% KOH with 10 vol.% IPA for wet etching at 63 °C was applied to extract the nanostructure. The fabricated SiNW had 70–85 nm full width at half maximum width, 90 nm thickness and 4 μm length. The SiNW was simulated using Sentaurus 3D software with the exact same size of the fabricated device. I–V characterization of the SiNW was measured and compared with simulation results. Using simulation results variation of carrier's concentrations, valence band edge energy and recombination generation rate for different applied voltage were investigated.

  9. Diamond Nanowires: A Novel Platform for Electrochemistry and Matrix-Free Mass Spectrometry

    Sabine Szunerits

    2015-05-01

    Full Text Available Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs, and more recently graphene and its derivatives, hold a central position. The large amount of work devoted to these materials is driven not only by their unique mechanical and electrical properties, but also by the advances made in synthetic methods to produce these materials in large quantities with reasonably controllable morphologies. While much less studied than CNTs and graphene, diamond nanowires, the diamond analogue of CNTs, hold promise for several important applications. Diamond nanowires display several advantages such as chemical inertness, high mechanical strength, high thermal and electrical conductivity, together with proven biocompatibility and existence of various strategies to functionalize their surface. The unique physicochemical properties of diamond nanowires have generated wide interest for their use as fillers in nanocomposites, as light detectors and emitters, as substrates for nanoelectronic devices, as tips for scanning probe microscopy as well as for sensing applications. In the past few years, studies on boron-doped diamond nanowires (BDD NWs focused on increasing their electrochemical active surface area to achieve higher sensitivity and selectivity compared to planar diamond interfaces. The first part of the present review article will cover the promising applications of BDD NWS for label-free sensing. Then, the potential use of diamond nanowires as inorganic substrates for matrix-free laser desorption/ionization mass spectrometry, a powerful label-free approach for quantification and identification of small compounds, will be discussed.

  10. Diamond nanowires: a novel platform for electrochemistry and matrix-free mass spectrometry.

    Szunerits, Sabine; Coffinier, Yannick; Boukherroub, Rabah

    2015-05-27

    Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs), and more recently graphene and its derivatives, hold a central position. The large amount of work devoted to these materials is driven not only by their unique mechanical and electrical properties, but also by the advances made in synthetic methods to produce these materials in large quantities with reasonably controllable morphologies. While much less studied than CNTs and graphene, diamond nanowires, the diamond analogue of CNTs, hold promise for several important applications. Diamond nanowires display several advantages such as chemical inertness, high mechanical strength, high thermal and electrical conductivity, together with proven biocompatibility and existence of various strategies to functionalize their surface. The unique physicochemical properties of diamond nanowires have generated wide interest for their use as fillers in nanocomposites, as light detectors and emitters, as substrates for nanoelectronic devices, as tips for scanning probe microscopy as well as for sensing applications. In the past few years, studies on boron-doped diamond nanowires (BDD NWs) focused on increasing their electrochemical active surface area to achieve higher sensitivity and selectivity compared to planar diamond interfaces. The first part of the present review article will cover the promising applications of BDD NWS for label-free sensing. Then, the potential use of diamond nanowires as inorganic substrates for matrix-free laser desorption/ionization mass spectrometry, a powerful label-free approach for quantification and identification of small compounds, will be discussed.

  11. Photoemission electron microscopy of localized surface plasmons in silver nanostructures at telecommunication wavelengths

    Mårsell, Erik; Larsen, Esben W.; Arnold, Cord L.; Xu, Hongxing; Mauritsson, Johan; Mikkelsen, Anders, E-mail: anders.mikkelsen@sljus.lu.se [Department of Physics, Lund University, P.O. Box 118, 22 100 Lund (Sweden)

    2015-02-28

    We image the field enhancement at Ag nanostructures using femtosecond laser pulses with a center wavelength of 1.55 μm. Imaging is based on non-linear photoemission observed in a photoemission electron microscope (PEEM). The images are directly compared to ultra violet PEEM and scanning electron microscopy (SEM) imaging of the same structures. Further, we have carried out atomic scale scanning tunneling microscopy on the same type of Ag nanostructures and on the Au substrate. Measuring the photoelectron spectrum from individual Ag particles shows a larger contribution from higher order photoemission processes above the work function threshold than would be predicted by a fully perturbative model, consistent with recent results using shorter wavelengths. Investigating a wide selection of both Ag nanoparticles and nanowires, field enhancement is observed from 30% of the Ag nanoparticles and from none of the nanowires. No laser-induced damage is observed of the nanostructures neither during the PEEM experiments nor in subsequent SEM analysis. By direct comparison of SEM and PEEM images of the same nanostructures, we can conclude that the field enhancement is independent of the average nanostructure size and shape. Instead, we propose that the variations in observed field enhancement could originate from the wedge interface between the substrate and particles electrically connected to the substrate.

  12. Formation of crystalline InGaO₃(ZnO)n nanowires via the solid-phase diffusion process using a solution-based precursor.

    Guo, Yujie; Van Bilzen, Bart; Locquet, Jean Pierre; Seo, Jin Won

    2015-12-11

    One-dimensional single crystalline InGaO3(ZnO)n (IGZO) nanostructures have great potential for various electrical and optical applications. This paper demonstrates for the first time, to our knowledge, a non-vacuum route for the synthesis of IGZO nanowires by annealing ZnO nanowires covered with solution-based IGZO precursor. This method results in nanowires with highly periodic IGZO superlattice structure. The phase transition of IGZO precursor during thermal treatment was systematically studied. Transmission electron microscopy studies reveal that the formation of the IGZO structure is driven by anisotropic inter-diffusion of In, Ga, and Zn atoms, and also by the crystallization of the IGZO precursor. Optical measurements using cathodoluminescence and UV-vis spectroscopy confirm that the nanowires consist of the IGZO compound with wide optical band gap and suppressed luminescence.

  13. Formation of crystalline InGaO_3(ZnO)_n nanowires via the solid-phase diffusion process using a solution-based precursor

    Guo, Yujie; Seo, Jin Won; Bilzen, Bart Van; Locquet, Jean Pierre

    2015-01-01

    One-dimensional single crystalline InGaO_3(ZnO)_n (IGZO) nanostructures have great potential for various electrical and optical applications. This paper demonstrates for the first time, to our knowledge, a non-vacuum route for the synthesis of IGZO nanowires by annealing ZnO nanowires covered with solution-based IGZO precursor. This method results in nanowires with highly periodic IGZO superlattice structure. The phase transition of IGZO precursor during thermal treatment was systematically studied. Transmission electron microscopy studies reveal that the formation of the IGZO structure is driven by anisotropic inter-diffusion of In, Ga, and Zn atoms, and also by the crystallization of the IGZO precursor. Optical measurements using cathodoluminescence and UV-vis spectroscopy confirm that the nanowires consist of the IGZO compound with wide optical band gap and suppressed luminescence. (paper)

  14. Layer-by-layer deposition of nanostructured CsPbBr3 perovskite thin films

    Reshetnikova, A. A.; Matyushkin, L. B.; Andronov, A. A.; Sokolov, V. S.; Aleksandrova, O. A.; Moshnikov, V. A.

    2017-11-01

    Layer-by-layer deposition of nanostructured perovskites cesium lead halide thin films is described. The method of deposition is based on alternate immersion of the substrate in the precursor solutions or colloidal solution of nanocrystals and methyl acetate/lead nitrate solution using the device for deposition of films by SILAR and dip-coating techniques. An example of obtaining a photosensitive structure based on nanostructures of ZnO nanowires and layers of CsBbBr3 nanocrystals is also shown.

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

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

    2011-01-01

    This study describes an integrated micro ‘‘factory’’ for the preparation of biological self-assembled peptide nanotubes and nanoparticles on a polymer chip, yielding controlled growth conditions. Self-assembled peptides constitute attractive building blocks for the fabrication of biological...... 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-assembled...

  16. Biotemplated Synthesis of PZT Nanowires

    2013-11-25

    electromechanical coupling coefficient , Y is the Young’s modulus, and Ri is intrinsic resistance. The PZT nanowire- based film is taken to have negligible...robotic actuation, and bioMEMS. Lead zirconate titanate ( PZT ), in particular, has attracted significant attention, owing to its superior...electromechanical conversion performance. Yet, the ability to synthesize crystalline PZT nanowires with reproducible and well-controlled properties remains a

  17. Silicon nanowires: structure and properties

    Nezhdanov, A.V.; Mashin, A.I.; Razuvaev, A.G.; Ershov, A.V.; Ignatov, S.K.

    2006-01-01

    An attempt to grow silicon nanowires has been made by electron beam evaporation on highly oriented pyrolytic substrate. Needle-like objects are located along the normal to a substrate (density 2 x 10 11 cm -2 ). For modeling quasi-one-dimensional objects calculations of nuclear structure and energy spectra have been accomplished. A fullerene-like structure Si 24 is proposed as a basic atomic configuration of silicon nanowires [ru

  18. One-dimensional titania nanostructures: Synthesis and applications in dye-sensitized solar cells

    Wang, Hao [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Guo, Zhiguang, E-mail: zguo@licp.cas.cn [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Shimin [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); Liu, Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-05-02

    One-dimensional (1D) titania (TiO{sub 2}) in the form of nanorods, nanowires, nanobelts and nanotubes have attracted much attention due to their unique physical, chemical and optical properties enabling extraordinary performance in biomedicine, sensors, energy storage, solar cells and photocatalysis. In this review, we mainly focus on synthetic methods for 1D TiO{sub 2} nanostructures and the applications of 1D TiO{sub 2} nanostructures in dye-sensitized solar cells (DSCs). Traditional nanoparticle-based DSCs have numerous grain boundaries and surface defects, which increase the charge recombination from photoanode to electrolyte. 1D TiO{sub 2} nanostructures can provide direct and rapid electron transport to the electron collecting electrode, indicating a promising choice for DSCs. We divide the applications of 1D TiO{sub 2} nanostructures in DSCs into four parts, that is, 1D TiO{sub 2} nanostructures only, 1D TiO{sub 2} nanostructure/nanoparticle composites, branched 1D TiO{sub 2} nanostructures, and 1D TiO{sub 2} nanostructures combined with other materials. This work will provide guidance for preparing 1D TiO{sub 2} nanostructures, and using them as photoanodes in efficient DSCs. - Graphical abstract: 1D TiO{sub 2} nanostructures which can provide direct and rapid pathways for electron transport have promising applications in dye-sensitized solar cells (DSCs). The synthetic methods and applications of 1D TiO{sub 2} nanostructures in DSCs are summarized in this review article.

  19. Rational design of octahedron and nanowire CeO2@MnO2 core-shell heterostructures with outstanding rate capability for asymmetric supercapacitors.

    Zhu, Shi Jin; Jia, Jia Qi; Wang, Tian; Zhao, Dong; Yang, Jian; Dong, Fan; Shang, Zheng Guo; Zhang, Yu Xin

    2015-10-14

    Two kinds of novel CeO2@MnO2 nanostructures have been synthesized via a self-assembly strategy. The as-prepared CeO2 nanowire@MnO2 nanostructures exhibited unprecedented pseudocapacitance performance (255 F g(-1)) with outstanding rate capability. A new mechanism based on the synergistic effect between CeO2 and MnO2 was proposed to interpret this phenomenon. When assembled as an asymmetric supercapacitor, an energy density of 27.5 W h kg(-1) with a maximum power density of 1.6 kW kg(-1) was achieved for CeO2 nanowire@MnO2 nanostructures.

  20. Plasmonic Nanostructures for Biosensor Applications

    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

  1. Developing 1D nanostructure arrays for future nanophotonics

    Cooke DG

    2006-01-01

    Full Text Available AbstractThere is intense and growing interest in one-dimensional (1-D nanostructures from the perspective of their synthesis and unique properties, especially with respect to their excellent optical response and an ability to form heterostructures. This review discusses alternative approaches to preparation and organization of such structures, and their potential properties. In particular, molecular-scale printing is highlighted as a method for creating organized pre-cursor structure for locating nanowires, as well as vapor–liquid–solid (VLS templated growth using nano-channel alumina (NCA, and deposition of 1-D structures with glancing angle deposition (GLAD. As regards novel optical properties, we discuss as an example, finite size photonic crystal cavity structures formed from such nanostructure arrays possessing highQand small mode volume, and being ideal for developing future nanolasers.

  2. Novel nanostructured materials for high energy density supercapacitors

    Yuan, C.Z.; Zhang, X.G. [Nanjing Univ. of Aeronautics and Astronautics (China). College of Material Science and Engineering

    2010-07-01

    Researchers are currently examining methods of improving energy density while not sacrificing the high power density of supercapacitors. In this study, nanostructured materials assembled from nanometer-sized building blocks with mesoporosity were synthesized in order investigate diffusion time, kinetics, and capacitances. Petal-like cobalt hydroxide Co(OH){sub 2} mesocrystals, urchin-like Co(OH){sub 2} and dicobalt tetroxide (Co{sub 2}O{sub 4}) ordered arrays as well as N{sub i}O microspheres were assembled from 0-D nanoparticles, 1-D mesoporous nanowires and nanobelts, and 2-D mesoporous nanopetals. The study showed that all the synthesized nanostructured materials delivered larger energy densities while showing electrochemical stability at high rates.

  3. Direct writing of metal nanostructures: lithographic tools for nanoplasmonics research.

    Leggett, Graham J

    2011-03-22

    Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials.

  4. Magnetism in carbon nanostructures

    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.

  5. Electrochemically grown rough-textured nanowires

    Tyagi, Pawan; Postetter, David; Saragnese, Daniel; Papadakis, Stergios J.; Gracias, David H.

    2010-01-01

    Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)-Au plating solution mixture that precipitates an Ag-Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices.

  6. Structural and tunneling properties of Si nanowires

    Montes Muñoz, Enrique

    2013-12-06

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green\\'s function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.

  7. Structural and tunneling properties of Si nanowires

    Montes Muñ oz, Enrique; Gkionis, Konstantinos; Rungger, Ivan; Sanvito, Stefano; Schwingenschlö gl, Udo

    2013-01-01

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green's function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.

  8. A silicon nanowire heater and thermometer

    Zhao, Xingyan; Dan, Yaping

    2017-07-01

    In the thermal conductivity measurements of thermoelectric materials, heaters and thermometers made of the same semiconducting materials under test, forming a homogeneous system, will significantly simplify fabrication and integration. In this work, we demonstrate a high-performance heater and thermometer made of single silicon nanowires (SiNWs). The SiNWs are patterned out of a silicon-on-insulator wafer by CMOS-compatible fabrication processes. The electronic properties of the nanowires are characterized by four-probe and low temperature Hall effect measurements. The I-V curves of the nanowires are linear at small voltage bias. The temperature dependence of the nanowire resistance allows the nanowire to be used as a highly sensitive thermometer. At high voltage bias, the I-V curves of the nanowire become nonlinear due to the effect of Joule heating. The temperature of the nanowire heater can be accurately monitored by the nanowire itself as a thermometer.

  9. Controlling nanowire emission profile using conical taper

    Gregersen, Niels; Nielsen, Torben Roland; Mørk, Jesper

    2008-01-01

    The influence of a conical taper on nanowire light emission is studied. For nanowires with divergent output beams, the introduction of tapers improves the emission profile and increase the collection efficiency of the detection optics....

  10. Analytical simulation of RBS spectra of nanowire samples

    Barradas, Nuno P., E-mail: nunoni@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 ao km 139,7, 2695-066 Bobadela LRS (Portugal); García Núñez, C. [Laboratorio de Electrónica y Semiconductores, Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Redondo-Cubero, A. [Laboratorio de Electrónica y Semiconductores, Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Shen, G.; Kung, P. [Department of Electrical and Computer Engineering, The University of Alabama, AL 35487 (United States); Pau, J.L. [Laboratorio de Electrónica y Semiconductores, Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2016-03-15

    Almost all, if not all, general purpose codes for analysis of Ion Beam Analysis data have been originally developed to handle laterally homogeneous samples only. This is the case of RUMP, NDF, SIMNRA, and even of the Monte Carlo code Corteo. General-purpose codes usually include only limited support for lateral inhomogeneity. In this work, we show analytical simulations of samples that consist of a layer of parallel oriented nanowires on a substrate, using a model implemented in NDF. We apply the code to real samples, made of vertical ZnO nanowires on a sapphire substrate. Two configurations of the nanowires were studied: 40 nm diameter, 4.1 μm height, 3.5% surface coverage; and 55 nm diameter, 1.1 μm height, 42% surface coverage. We discuss the accuracy and limits of applicability of the analysis.

  11. Hybrid Surface Plasmon Polariton Modes of Subwavelength Nanowire Resonators

    Filonenko, Konstantin; Duggen, Lars; Willatzen, Morten

    2015-01-01

    -localized gap plasmon mode are studied depending on the vacuum wavelength. In order to directly compare resonators, where metal and semiconductor nanowires are employed, we consider the two resonators, both including silver slab and magnesium fluoride gap region, as is shown in figure. The two compared......We perform Comsol simulations of two types of hybrid plasmonic resonator configurations, similar to those proposed for nanowire plasmonic laser in [1] and [2]. In both references the nanowire - based plasmonic resonators are studied, which overall sizes are larger than the wavelength in vacuum....... However, it is advantageous for the nanolaser to have subwavelength sizes at least in two dimensions. Therefore, we study the two configurations and the hybrid mode behavior in the case, where resonator sizes are smaller than the half of the wavelength in vacuum. First, we assume finite dimensions...

  12. Towards quantum dots on GaAs nanowires

    Moesl, Johannes; Ludwig, Stefan [Fakultaet fuer Physik, Center for NanoScience, LMU Munich, Geschwister-Scholl- Platz 1, D-80539 Muenchen (Germany); Fontcuberta i Morral, Anna [TU Munich, Walter Schottky Institut, Am Coulombwall 3, 85748 Garching (Germany); EPF, Lausanne (Switzerland)

    2009-07-01

    Semiconductor nanowires is an emergent research topic in the field of nanoelectronics, as they form an excellent building block for 0D and 1D applications and allow novel architectures and material combinations. We study electronic transport properties of catalyst-free MBE grown GaAs nanowires, p-doped at a number of different doping levels. Detailed characterization of the wires including electronic contacts fabricated by e-beam lithography and based on palladium or annealed zinc-silver alloys are discussed. Contact properties and a pronounced hysteresis of the current through the nanowires, as a backgate-voltage is swept, are explained within tentative models. In addition we present first transport measurements on quantum dots, which are defined electrostatically as well as by etched constrictions.

  13. Synthesis of Cu Doped ZnO Nanostructures for Ultra Violet Sensing

    Nazar Abbas SHAH; Muhammad ABID; Muhammad AMIN; Rahat AFRIN; Syed Zafar ILYAS

    2015-01-01

    This paper mainly focused on the synthesis of zinc oxide nanostructures, their characterization and their ultra violet light sensing response at room temperature. Nanowires, nanobelts and nanosheets were synthesized by varying doping material copper by using vapor transport technique governed by the vapor-liquid-solid or vapor-solid mechanisms. The structural, morphological and optical characterization was carried out using X-ray diffraction, scanning electron microscopy, energy dispersive X-...

  14. The influence of surfaces on the transient terahertz conductivity and electron mobility of GaAs nanowires

    Joyce, Hannah J; Baig, Sarwat A; Parkinson, Patrick; Davies, Christopher L; Boland, Jessica L; Herz, Laura M; Johnston, Michael B; Tan, H Hoe; Jagadish, Chennupati

    2017-01-01

    Bare unpassivated GaAs nanowires feature relatively high electron mobilities (400–2100 cm 2 V −1 s −1 ) and ultrashort charge carrier lifetimes (1–5 ps) at room temperature. These two properties are highly desirable for high speed optoelectronic devices, including photoreceivers, modulators and switches operating at microwave and terahertz frequencies. When engineering these GaAs nanowire-based devices, it is important to have a quantitative understanding of how the charge carrier mobility and lifetime can be tuned. Here we use optical-pump–terahertz-probe spectroscopy to quantify how mobility and lifetime depend on the nanowire surfaces and on carrier density in unpassivated GaAs nanowires. We also present two alternative frameworks for the analysis of nanowire photoconductivity: one based on plasmon resonance and the other based on Maxwell–Garnett effective medium theory with the nanowires modelled as prolate ellipsoids. We find the electron mobility decreases significantly with decreasing nanowire diameter, as charge carriers experience increased scattering at nanowire surfaces. Reducing the diameter from 50 nm to 30 nm degrades the electron mobility by up to 47%. Photoconductivity dynamics were dominated by trapping at saturable states existing at the nanowire surface, and the trapping rate was highest for the nanowires of narrowest diameter. The maximum surface recombination velocity, which occurs in the limit of all traps being empty, was calculated as 1.3  ×  10 6 cm s −1 . We note that when selecting the optimum nanowire diameter for an ultrafast device, there is a trade-off between achieving a short lifetime and a high carrier mobility. To achieve high speed GaAs nanowire devices featuring the highest charge carrier mobilities and shortest lifetimes, we recommend operating the devices at low charge carrier densities. (paper)

  15. The ITO-capped WO{sub 3} nanowires biosensor based on field-effect transistor in label-free protein sensing

    Shariati, Mohsen [Sharif University of Technology, Institute for Nanoscience and Nanotechnology, Tehran (Iran, Islamic Republic of)

    2017-05-15

    The fabrication of ITO-capped WO{sub 3} nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO{sub 3} nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was 'label-free' and depended on bio-molecule's intrinsic charge. For nanowires synthesis, the vapor-liquid-solid mechanism was used. Nanowires were beyond a few hundred nanometers in lengths and around 15-20 nm in diameter, while the globe cap's size on the nanowires was around 15-25 nm. The indium tin oxide (ITO) played as catalyst in nanofabrication for WO{sub 3} nanowires growth and had outstanding role in bio-sensing especially for bio-molecule adherence. In applied electric field presence, the fabricated device showed the great potential to enhance medical diagnostics. (orig.)

  16. The lateral In2O3 nanowires and pyramid networks manipulation by controlled substrate surface energy in annealing evolution

    Shariati, Mohsen; Darjani, Mojtaba

    2016-02-01

    The continuous laterally aligned growth of In2O3 nanocrystal networks extended with nanowire and pyramid connections under annealing influence has been reported. These nanostructures have been grown on Si substrate by using oxygen-assisted annealing process through PVD growth technique. The formation of In2O3 nanocrystals has been achieved by the successive growth of critical self-nucleated condensation in three orientations. The preferred direction was the route between two pyramids especially in the smallest surface energy. The effects of substrate temperature in annealing process on the morphological properties of the as-grown nanostructures were investigated. The annealing technique showed that by controlling the surface energy, the morphology of structures was changed from unregulated array to defined nanostructures; especially nanowires 50 nm in width. The obtained nanostructures also were investigated by the (transmission electron microscopy) TEM, Raman spectrum and the (X-ray diffraction) XRD patterns. They indicated that the self-assembled In2O3 nanocrystal networks have been fabricated by the vapor-solid (VS) growth mechanism. The growth mechanism process was prompted to attribute the relationship among the kinetics parameters, surface diffusion and morphology of nanostructures.

  17. The spontaneous formation and plasmonic properties of ultrathin gold–silver nanorods and nanowires stabilized in oleic acid

    Crespo, Julian

    2015-10-02

    Ultrathin Au-Ag alloy nanorods and nanowires of different lengths and ca. 1.9 nm diameter are prepared through a low-temperature decomposition of the precursor [AuAg(CF)(OEt)] in oleic acid. This nanostructure formation has been studied through TEM, HRTEM, EDS, HS-SPME-GC-MS and F NMR spectroscopy. The UNRs and UNWs display a length-dependent broad band in the mid-IR region that is related to the longitudinal mode of the surface plasmon resonance of the ultrathin nanostructures.

  18. The spontaneous formation and plasmonic properties of ultrathin gold–silver nanorods and nanowires stabilized in oleic acid

    Crespo, Julian; Ló pez-De-Luzuriaga, José M.; Monge, Miguel; Elena Olmos, M.; Rodrí guez-Castillo, Marí a; Cormary, Benoî t; Soulantica, Katerina; Sestu, Matteo; Falqui, Andrea

    2015-01-01

    Ultrathin Au-Ag alloy nanorods and nanowires of different lengths and ca. 1.9 nm diameter are prepared through a low-temperature decomposition of the precursor [AuAg(CF)(OEt)] in oleic acid. This nanostructure formation has been studied through TEM, HRTEM, EDS, HS-SPME-GC-MS and F NMR spectroscopy. The UNRs and UNWs display a length-dependent broad band in the mid-IR region that is related to the longitudinal mode of the surface plasmon resonance of the ultrathin nanostructures.

  19. Electrochemical synthesis of highly crystalline copper nanowires

    Kaur, Amandeep; Gupta, Tanish; Kumar, Akshay; Kumar, Sanjeev; Singh, Karamjeet; Thakur, Anup

    2015-01-01

    Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

  20. Confocal filtering in cathodoluminescence microscopy of nanostructures

    Narváez, Angela C.; Weppelman, I. Gerward C.; Moerland, Robert J.; Hoogenboom, Jacob P.; Kruit, Pieter

    2014-06-01

    Cathodoluminescence (CL) microscopy allows optical characterization of nanostructures at high spatial resolution. At the nanoscale, a main challenge of the technique is related to the background CL generated within the sample substrate. Here, we implement confocal detection of the CL signal to minimize the background contribution to the measurement. Nano-phosphors were used as point sources to evaluate the filtering capabilities of our confocal CL system, obtaining an axial intensity profile with 2.7 μm full width at half maximum for the central peak, in good correspondence with theoretical expectations. Considering the electron interaction volume, we found that the confocal filter becomes effective for electron energies above 20 keV, when using a 25 μm pinhole (0.86 Airy units). To illustrate our approach, we present confocal CL imaging of gold nanowires and triangular shaped plates deposited on an indium-tin oxide covered glass substrate, comparing the images with those obtained in standard unfiltered CL detection. The results show that confocal CL microscopy is a valuable tool for the investigation of nanostructures on highly cathodoluminescent substrates, widely used in biological and optical applications.

  1. Confocal filtering in cathodoluminescence microscopy of nanostructures

    Narváez, Angela C., E-mail: a.c.narvaez@tudelft.nl, E-mail: j.p.hoogenboom@tudelft.nl; Weppelman, I. Gerward C.; Moerland, Robert J.; Hoogenboom, Jacob P., E-mail: a.c.narvaez@tudelft.nl, E-mail: j.p.hoogenboom@tudelft.nl; Kruit, Pieter [Imaging Physics, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands)

    2014-06-23

    Cathodoluminescence (CL) microscopy allows optical characterization of nanostructures at high spatial resolution. At the nanoscale, a main challenge of the technique is related to the background CL generated within the sample substrate. Here, we implement confocal detection of the CL signal to minimize the background contribution to the measurement. Nano-phosphors were used as point sources to evaluate the filtering capabilities of our confocal CL system, obtaining an axial intensity profile with 2.7 μm full width at half maximum for the central peak, in good correspondence with theoretical expectations. Considering the electron interaction volume, we found that the confocal filter becomes effective for electron energies above 20 keV, when using a 25 μm pinhole (0.86 Airy units). To illustrate our approach, we present confocal CL imaging of gold nanowires and triangular shaped plates deposited on an indium-tin oxide covered glass substrate, comparing the images with those obtained in standard unfiltered CL detection. The results show that confocal CL microscopy is a valuable tool for the investigation of nanostructures on highly cathodoluminescent substrates, widely used in biological and optical applications.

  2. Hydrothermal synthesis of ultralong and single-crystalline Cd(OH)2 nanowires using alkali salts as mineralizers.

    Tang, Bo; Zhuo, Linhai; Ge, Jiechao; Niu, Jinye; Shi, Zhiqiang

    2005-04-18

    Ultralong and single-crystalline Cd(OH)(2) nanowires were fabricated by a hydrothermal method using alkali salts as mineralizers. The morphology and size of the final products strongly depend on the effects of the alkali salts (e.g., KCl, KNO(3), and K(2)SO(4) or NaCl, NaNO(3), and Na(2)SO(4)). When the salt is absent, only nanoparticles are observed in TEM images of the products. The 1D nanostructure growth method presented herein offers an excellent tool for the design of other advanced materials with anisotropic properties. In addition, the Cd(OH)(2) nanowires might act as a template or precursor that is potentially converted into 1D cadmium oxide through dehydration or into 1D nanostructures of other functional materials (e.g., CdS, CdSe).

  3. In-situ magnetization/heating electron holography to study the magnetic ordering in arrays of nickel metallic nanowires

    Eduardo Ortega

    2018-05-01

    Full Text Available Magnetic nanostructures of different size, shape, and composition possess a great potential to improve current technologies like data storage and electromagnetic sensing. In thin ferromagnetic nanowires, their magnetization behavior is dominated by the competition between magnetocrystalline anisotropy (related to the crystalline structure and shape anisotropy. In this way electron diffraction methods like precession electron diffraction (PED can be used to link the magnetic behavior observed by Electron Holography (EH with its crystallinity. Using off-axis electron holography under Lorentz conditions, we can experimentally determine the magnetization distribution over neighboring nanostructures and their diamagnetic matrix. In the case of a single row of nickel nanowires within the alumina template, the thin TEM samples showed a dominant antiferromagnetic arrangement demonstrating long-range magnetostatic interactions playing a major role.

  4. Optical Biosensors Based on Semiconductor Nanostructures

    Raúl J. Martín-Palma

    2009-06-01

    Full Text Available The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented.

  5. Simulation of thermal stress and buckling instability in Si/Ge and Ge/Si core/shell nanowires.

    Das, Suvankar; Moitra, Amitava; Bhattacharya, Mishreyee; Dutta, Amlan

    2015-01-01

    The present study employs the method of atomistic simulation to estimate the thermal stress experienced by Si/Ge and Ge/Si, ultrathin, core/shell nanowires with fixed ends. The underlying technique involves the computation of Young's modulus and the linear coefficient of thermal expansion through separate simulations. These two material parameters are combined to obtain the thermal stress on the nanowires. In addition, the thermally induced stress is perceived in the context of buckling instability. The analysis provides a trade-off between the geometrical and operational parameters of the nanostructures. The proposed methodology can be extended to other materials and structures and helps with the prediction of the conditions under which a nanowire-based device might possibly fail due to elastic instability.

  6. Nanostructured Materials

    2012-08-30

    potassium hydroxide (2.088 mg) were added to a 10 mL volumetric flask. The balance of the volume to 10 mL was filled with ethanol. The contents were...water (0.27 g), and potassium hydroxide (2.088 mg) were added to a 10 mL volumetric flask. The balance of the volume to 10 mL was filled with ethanol...modification of metals, fill- ers, and composites can be prepared. Preferred reactive groups include but are not limited to silanols, siloxides, meth- acrylates

  7. Emergence of Quantum Phase-Slip Behaviour in Superconducting NbN Nanowires: DC Electrical Transport and Fabrication Technologies

    Nicolas G. N. Constantino

    2018-06-01

    Full Text Available Superconducting nanowires undergoing quantum phase-slips have potential for impact in electronic devices, with a high-accuracy quantum current standard among a possible toolbox of novel components. A key element of developing such technologies is to understand the requirements for, and control the production of, superconducting nanowires that undergo coherent quantum phase-slips. We present three fabrication technologies, based on using electron-beam lithography or neon focussed ion-beam lithography, for defining narrow superconducting nanowires, and have used these to create nanowires in niobium nitride with widths in the range of 20–250 nm. We present characterisation of the nanowires using DC electrical transport at temperatures down to 300 mK. We demonstrate that a range of different behaviours may be obtained in different nanowires, including bulk-like superconducting properties with critical-current features, the observation of phase-slip centres and the observation of zero conductance below a critical voltage, characteristic of coherent quantum phase-slips. We observe critical voltages up to 5 mV, an order of magnitude larger than other reports to date. The different prominence of quantum phase-slip effects in the various nanowires may be understood as arising from the differing importance of quantum fluctuations. Control of the nanowire properties will pave the way for routine fabrication of coherent quantum phase-slip nanowire devices for technology applications.

  8. Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy

    Joyce, Hannah J; Docherty, Callum J; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B; Gao Qiang; Tan, H Hoe; Jagadish, Chennupati

    2013-01-01

    We have performed a comparative study of ultrafast charge carrier dynamics in a range of III–V nanowires using optical pump–terahertz probe spectroscopy. This versatile technique allows measurement of important parameters for device applications, including carrier lifetimes, surface recombination velocities, carrier mobilities and donor doping levels. GaAs, InAs and InP nanowires of varying diameters were measured. For all samples, the electronic response was dominated by a pronounced surface plasmon mode. Of the three nanowire materials, InAs nanowires exhibited the highest electron mobilities of 6000 cm 2 V −1 s −1 , which highlights their potential for high mobility applications, such as field effect transistors. InP nanowires exhibited the longest carrier lifetimes and the lowest surface recombination velocity of 170 cm s −1 . This very low surface recombination velocity makes InP nanowires suitable for applications where carrier lifetime is crucial, such as in photovoltaics. In contrast, the carrier lifetimes in GaAs nanowires were extremely short, of the order of picoseconds, due to the high surface recombination velocity, which was measured as 5.4 × 10 5   cm s −1 . These findings will assist in the choice of nanowires for different applications, and identify the challenges in producing nanowires suitable for future electronic and optoelectronic devices. (paper)

  9. From dopyballs to nanowires

    Smalley, R E [Rice Quantum Inst. and Depts. of Chemistry and Physics, Rice Univ., Houston, TX (United States)

    1993-04-19

    Consideration of the factors involved in the production of fullerene nanotubes in carbon arcs leads to the notion that a high electric field may be the critical factor that causes the tubes to grow. This thought then leads to a suggestion that it may be possible to grow continuous fullerene fibers many centimeters in length by an electric-field-and-laser induced pyrolysis of gas phase hydrocarbons of fullerenes on the tip of the growing fiber as it extends out from its place of attachment on a high voltage needle. Use of metal- or boron-doped fullerenes (dopyballs) in such an apparatus may lead to the production of doped fullerene fiber nanowires of high strength and conductivity. (orig.)

  10. Resonance of curved nanowires

    Calabri, L [CNR-INFM-National Research Center on nanoStructures and bioSystems at Surfaces (S3), Via Campi 213/a, 41100 Modena (Italy); Pugno, N [Department of Structural Engineering and Geotechnics, Politecnico di Torino, Turin (Italy); Ding, W [Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208-3111 (United States); Ruoff, R S [Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208-3111 (United States)

    2006-08-23

    The effects of non-ideal experimental configuration on the mechanical resonance of boron (B) nanowires (NWs) were studied to obtain the corrected value for the Young's modulus. The following effects have been theoretically considered: (i) the presence of intrinsic curvature (ii) non-ideal clamps (iii) spurious masses (iv) coating layer, and (v) large displacements. An energy-based analytical analysis was developed to treat such effects and their interactions. Here, we focus on treating the effect of the intrinsic curvature on the mechanical resonance. The analytical approach has been confirmed by numerical FEM analysis. A parallax method was used to obtain the three-dimensional geometry of the NW.

  11. Corrosion detection of nanowires by magnetic sensors

    Kosel, Jü rgen; Amara, Selma; Ivanov, Iurii; Blanco, Mario

    2017-01-01

    Disclosed are various embodiments related to a corrosion detection device for detecting corrosive environments. A corrosion detection device comprises a magnetic sensor and at least one magnetic nanowire disposed on the magnetic sensor. The magnetic sensor is configured to detect corrosion of the one or more magnetic nanowires based at least in part on a magnetic field of the one or more magnetic nanowires.

  12. Corrosion detection of nanowires by magnetic sensors

    Kosel, Jürgen

    2017-10-05

    Disclosed are various embodiments related to a corrosion detection device for detecting corrosive environments. A corrosion detection device comprises a magnetic sensor and at least one magnetic nanowire disposed on the magnetic sensor. The magnetic sensor is configured to detect corrosion of the one or more magnetic nanowires based at least in part on a magnetic field of the one or more magnetic nanowires.

  13. Si/SiGe heterointerfaces in one-, two-, and three-dimensional nanostructures: their impact on SiGe light emission

    Lockwood, David; Wu, Xiaohua; Baribeau, Jean-Marc; Mala, Selina; Wang, Xialou; Tsybeskov, Leonid

    2016-03-01

    Fast optical interconnects together with an associated light emitter that are both compatible with conventional Si-based complementary metal-oxide- semiconductor (CMOS) integrated circuit technology is an unavoidable requirement for the next-generation microprocessors and computers. Self-assembled Si/Si1-xGex nanostructures, which can emit light at wavelengths within the important optical communication wavelength range of 1.3 - 1.55 μm, are already compatible with standard CMOS practices. However, the expected long carrier radiative lifetimes observed to date in Si and Si/Si1-xGex nanostructures have prevented the attainment of efficient light-emitting devices including the desired lasers. Thus, the engineering of Si/Si1-xGex heterostructures having a controlled composition and sharp interfaces is crucial for producing the requisite fast and efficient photoluminescence (PL) at energies in the range 0.8-0.9 eV. In this paper we assess how the nature of the interfaces between SiGe nanostructures and Si in heterostructures strongly affects carrier mobility and recombination for physical confinement in three dimensions (corresponding to the case of quantum dots), two dimensions (corresponding to quantum wires), and one dimension (corresponding to quantum wells). The interface sharpness is influenced by many factors such as growth conditions, strain, and thermal processing, which in practice can make it difficult to attain the ideal structures required. This is certainly the case for nanostructure confinement in one dimension. However, we demonstrate that axial Si/Ge nanowire (NW) heterojunctions (HJs) with a Si/Ge NW diameter in the range 50 - 120 nm produce a clear PL signal associated with band-to-band electron-hole recombination at the NW HJ that is attributed to a specific interfacial SiGe alloy composition. For three-dimensional confinement, the experiments outlined here show that two quite different Si1-xGex nanostructures incorporated into a Si0.6Ge0.4 wavy

  14. Kinetically controlled synthesis of large-scale morphology-tailored silver nanostructures at low temperature

    Zhang, Ling; Zhao, Yuda; Lin, Ziyuan; Gu, Fangyuan; Lau, Shu Ping; Li, Li; Chai, Yang

    2015-08-01

    Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology-tailored Ag nanostructures, which is significant to the controllable fabrication of Ag nanostructures and fundamental understanding of the growth kinetics.Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology

  15. Molecular Beam Epitaxy-Grown InGaN Nanowires and Nanomushrooms for Solid State Lighting

    Gasim, Anwar A.

    2012-05-01

    InGaN is a promising semiconductor for solid state lighting thanks to its bandgap which spans the entire visible regime of the electromagnetic spectrum. InGaN is grown heteroepitaxially due to the absence of a native substrate; however, this results in a strained film and a high dislocation density—two effects that have been associated with efficiency droop, which is the disastrous drop in efficiency of a light-emitting diode (LED) as the input current increases. Heteroepitaxially grown nanowires have recently attracted great interest due to their property of eliminating the detrimental effects of the lattice mismatch and the corollary efficiency droop. In this study, InGaN nanowires were grown on a low-cost Si (111) substrate via molecular beam epitaxy. Unique nanostructures, taking the form of mushrooms, have been observed in localized regions on the samples. These nanomushrooms consist of a nanowire body with a wide cap on top. Photoluminescence characterization revealed that the nanowires emit violet-blue, whilst the nanomushrooms emit a broad yellow-orange-red luminescence. The simultaneous emission from the nanowires and nanomushrooms forms white light. Structural characterization of a single nanomushroom via transmission electron microscopy revealed a simultaneous increase in indium and decrease in gallium at the interface between the body and the cap. Furthermore, the cap itself was found to be indium-rich, confirming it as the source of the longer wavelength yellow-orange-red luminescence. It is believed that the nanomushroom cap formed as a consequence of the saturation of growth on the c-plane of the nanowire. It is proposed that the formation of an indium droplet on the tip of the nanowire saturated growth on the c-plane, forcing the indium and gallium adatoms to incorporate on the sidewall m-planes instead, but only at the nanowire tip. This resulted in the formation of a mushroom-like cap on the tip. How and why the indium droplets formed is not

  16. Designing Diameter-Modulated Heterostructure Nanowires of PbTe/Te by Controlled Dewetting.

    Kumar, Abinash; Kundu, Subhajit; Samantaray, Debadarshini; Kundu, Paromita; Zanaga, Daniele; Bals, Sara; Ravishankar, N

    2017-12-13

    Heterostructures consisting of semiconductors with controlled morphology and interfaces find applications in many fields. A range of axial, radial, and diameter-modulated nanostructures have been synthesized primarily using vapor phase methods. Here, we present a simple wet chemical routine to synthesize heterostructures of PbTe/Te using Te nanowires as templates. A morphology evolution study for the formation of these heterostructures has been performed. On the basis of these control experiments, a pathway for the formation of these nanostructures is proposed. Reduction of a Pb precursor to Pb on Te nanowire templates followed by interdiffusion of Pb/Te leads to the formation of a thin shell of PbTe on the Te wires. Controlled dewetting of the thin shell leads to the formation of cube-shaped PbTe that is periodically arranged on the Te wires. Using control experiments, we show that different reactions parameters like rate of addition of the reducing agent, concentration of Pb precursor and thickness of initial Te nanowire play a critical role in controlling the spacing between the PbTe cubes on the Te wires. Using simple surface energy arguments, we propose a mechanism for the formation of the hybrid. The principles presented are general and can be exploited for the synthesis of other nanoscale heterostructures.

  17. Novel Size and Surface Oxide Effects in Silicon Nanowires as Lithium Battery Anodes

    McDowell, Matthew T.

    2011-09-14

    With its high specific capacity, silicon is a promising anode material for high-energy lithium-ion batteries, but volume expansion and fracture during lithium reaction have prevented implementation. Si nanostructures have shown resistance to fracture during cycling, but the critical effects of nanostructure size and native surface oxide on volume expansion and cycling performance are not understood. Here, we use an ex situ transmission electron microscopy technique to observe the same Si nanowires before and after lithiation and have discovered the impacts of size and surface oxide on volume expansion. For nanowires with native SiO2, the surface oxide can suppress the volume expansion during lithiation for nanowires with diameters <∼50 nm. Finite element modeling shows that the oxide layer can induce compressive hydrostatic stress that could act to limit the extent of lithiation. The understanding developed herein of how volume expansion and extent of lithiation can depend on nanomaterial structure is important for the improvement of Si-based anodes. © 2011 American Chemical Society.

  18. TiO2 Nanowire Networks Prepared by Titanium Corrosion and Their Application to Bendable Dye-Sensitized Solar Cells

    Saera Jin

    2017-10-01

    Full Text Available TiO2 nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The wet corroded foils were utilized as the photoanodes of bendable dye-sensitized solar cells (DSSCs, which exhibited a power conversion efficiency of 1.11% under back illumination.

  19. TiO₂ Nanowire Networks Prepared by Titanium Corrosion and Their Application to Bendable Dye-Sensitized Solar Cells.

    Jin, Saera; Shin, Eunhye; Hong, Jongin

    2017-10-12

    TiO₂ nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH) solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The wet corroded foils were utilized as the photoanodes of bendable dye-sensitized solar cells (DSSCs), which exhibited a power conversion efficiency of 1.11% under back illumination.

  20. Systems and methods for large-scale nanotemplate and nanowire fabrication

    Vidal, Enrique Vilanova; Alfadhel, Ahmed; Ivanov, Iurii; Kosel, Jü rgen

    2016-01-01

    Systems and methods for largescale nanotemplate and nanowire fabrication are provided. The system can include a sample holder and one or more chemical containers fluidly connected to the sample holder. The sample holder can be configured to contain