WorldWideScience

Sample records for bioelectronic silicon nanowire

  1. Nano-Bioelectronics.

    Science.gov (United States)

    Zhang, Anqi; Lieber, Charles M

    2016-01-13

    Nano-bioelectronics represents a rapidly expanding interdisciplinary field that combines nanomaterials with biology and electronics and, in so doing, offers the potential to overcome existing challenges in bioelectronics. In particular, shrinking electronic transducer dimensions to the nanoscale and making their properties appear more biological can yield significant improvements in the sensitivity and biocompatibility and thereby open up opportunities in fundamental biology and healthcare. This review emphasizes recent advances in nano-bioelectronics enabled with semiconductor nanostructures, including silicon nanowires, carbon nanotubes, and graphene. First, the synthesis and electrical properties of these nanomaterials are discussed in the context of bioelectronics. Second, affinity-based nano-bioelectronic sensors for highly sensitive analysis of biomolecules are reviewed. In these studies, semiconductor nanostructures as transistor-based biosensors are discussed from fundamental device behavior through sensing applications and future challenges. Third, the complex interface between nanoelectronics and living biological systems, from single cells to live animals, is reviewed. This discussion focuses on representative advances in electrophysiology enabled using semiconductor nanostructures and their nanoelectronic devices for cellular measurements through emerging work where arrays of nanoelectronic devices are incorporated within three-dimensional cell networks that define synthetic and natural tissues. Last, some challenges and exciting future opportunities are discussed. PMID:26691648

  2. Silicon nanowire hybrid photovoltaics

    KAUST Repository

    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.

  3. Silicon nanowire transistors

    CERN Document Server

    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...

  4. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

    2009-08-04

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

  5. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  6. Gallium-Catalyzed Silicon Oxide Nanowire Growth

    Institute of Scientific and Technical Information of China (English)

    Zheng Wei Pan; Sheng Dai; Douglas H.Lowndes

    2005-01-01

    Silicon oxide nanowires tend to assemble into various complex morphologies through a metalcatalyzed vapor-liquid-solid (VLS) growth process. This article summarizes our recent efforts in the controlled growth of silicon oxide nanowire assemblies by using molten gallium as the catalyst and silicon wafer,SiO powder, or silane (SiH4) as the silicon sources. Silicon oxide nanowire assemblies with morphologies of carrotlike, cometlike, gourdlike, spindlelike, badmintonlike, sandwichlike, etc. were obtained. Although the morphologies of the nanowire assemblies are temperature- and silicon source-dependent, they share similar structural and compositional features: all the assemblies contain a microscale spherical liquid Ga ball and a highly aligned, closely packed amorphous silicon oxide nanowire bunch. The Ga-catalyzed silicon oxide nanowire growth reveals several interesting new nanowire growth phenomena that expand our knowledge of the conventional VLS nanowire growth mechanism.

  7. Semiconducting silicon nanowires for biomedical applications

    CERN Document Server

    Coffer, JL

    2014-01-01

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

  8. Printed Bioelectronics

    OpenAIRE

    Turner, Anthony

    2013-01-01

    Printed Bioelectronics   Anthony P. F. Turner   Biosensors and Bioelectronics Centre, IFM, Linköping University, Linköping S-58183, Sweden.      www.ifm.liu.se/biosensors     This lecture will consider how the recent emergence of printed bioelectronics can offer new solutions to distributed diagnostics for the maintenance of wellbeing, management of an ageing population, food security and environmental safety.   The adaptation of screen printing for the production of enzy...

  9. DNA hybridization on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shalini, E-mail: shalinsin@gmail.co [Electronic Materials Division, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Faculty of Life Science, Aligarh Muslim University, Aligarh-202001 (India); Zack, Jyoti [Dr. B.R Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007 (India); Kumar, Dinesh; Srivastava, S.K.; Govind [Electronic Materials Division, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Saluja, Daman [Dr. B.R Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007 (India); Khan, M.A. [Faculty of Life Science, Aligarh Muslim University, Aligarh-202001 (India); Singh, P.K. [Electronic Materials Division, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Marg, New Delhi-110012 (India)

    2010-11-30

    Nanowire-based detection strategies provide promising new routes to bioanalysis and indeed are attractive to conventional systems because of their small size, high surface-to-volume ratios, electronic, and optical properties. A sequence-specific detection of single-stranded oligonucleotides using silicon nanowires (SiNWs) is demonstrated. The surface of the SiNWs is functionalized with densely packed organic monolayer via hydrosilylation for covalent attachment. Subsequently, deoxyribonucleic acid (DNA) is immobilized to recognize the complementary target DNA. The biomolecular recognition properties of the nanowires are tested via hybridization with {sup {gamma}P32} tagged complementary and non-complementary DNA oligonucleotides, showing good selectivity and reversibility. No significant non-specific binding to the incorrect sequences is observed. X-ray photoelectron spectroscopy, fluorescence imaging, and nanodrop techniques are used to characterize the modified SiNWs and covalent attachment with DNA. The results show that SiNWs are excellent substrates for the absorption, stabilization and detection of DNA sequences and could be used for DNA microarrays and micro fabricated SiNWs DNA sensors.

  10. Silicon carbide nanowires synthesized with phenolic resin and silicon powders

    Science.gov (United States)

    Zhao, Hongsheng; Shi, Limin; Li, Ziqiang; Tang, Chunhe

    2009-02-01

    Large-scale silicon carbide nanowires with the lengths up to several millimeters were synthesized by a coat-mix, moulding, carbonization, and high-temperature sintering process, using silicon powder and phenolic resin as the starting materials. Ordinary SiC nanowires, bamboo-like SiC nanowires, and spindle SiC nanochains are found in the fabricated samples. The ordinary SiC nanowire is a single-crystal SiC phase with a fringe spacing of 0.252 nm along the [1 1 1] growth direction. Both of the bamboo-like SiC nanowires and spindle SiC nanochains exhibit uniform periodic structures. The bamboo-like SiC nanowires consist of amorphous stem and single-crystal knots, while the spindle SiC nanochains consist of uniform spindles which grow uniformly on the entire nanowires.

  11. Mechanical properties of Silicon Carbide Nanowires

    Science.gov (United States)

    Alkhateeb, Abdullah; Zhang, Daqing; McIlroy, David; Aston, David Eric

    2004-05-01

    Silicon carbide nanowires could be potentially useful for high strength materials which lead to the interest in understanding their mechanical properties. In this report we use the digital pulse force microscopy to analyze the mechanical properties of SiC nanowires .Stiffness and adhesion images of SiC nanowires on silicon grating were obtained and calibrated force-distance curves were plotted along the wire which spans on a 1.5 micron trench. Moreover, spring constant and Young's modules have been calculated from the linear part of the force-distance curves.

  12. Superconductive silicon nanowires using gallium beam lithography.

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Jarecki, Robert Leo,

    2014-01-01

    This work was an early career LDRD investigating the idea of using a focused ion beam (FIB) to implant Ga into silicon to create embedded nanowires and/or fully suspended nanowires. The embedded Ga nanowires demonstrated electrical resistivity of 5 m-cm, conductivity down to 4 K, and acts as an Ohmic silicon contact. The suspended nanowires achieved dimensions down to 20 nm x 30 nm x 10 m with large sensitivity to pressure. These structures then performed well as Pirani gauges. Sputtered niobium was also developed in this research for use as a superconductive coating on the nanowire. Oxidation characteristics of Nb were detailed and a technique to place the Nb under tensile stress resulted in the Nb resisting bulk atmospheric oxidation for up to years.

  13. Synthesis of silicon and germanium nanowires.

    Energy Technology Data Exchange (ETDEWEB)

    Clement, Teresa J. (Arizona State University); Hsu, Julia W. P.

    2007-11-01

    The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant dependence on precursor pressure and growth temperature for the synthesis of silicon and germanium nanowires is observed, depending on the stability of the specific precursor used. Also, the presence of a nucleation time for the onset of nanowire growth has been found using our new in situ optical reflectometry technique.

  14. Silicon nanowire properties from theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Scheel, H.M.

    2007-09-10

    Silicon has played an outstanding role at the end of the 20th century and is still one of the most important components for micro computing. In recent years the ability to miniaturize semiconductor structures and devices to nanometer length scales has opened an all new field of physics, i.e. nanoscience. Simply by miniaturizing the size of semiconducting structures the physics describing electronic or vibronic properties has to be altered fundamentally leading to new phenomena and interesting effects. For silicon the two major mile-stones where the fabrication of porous silicon and later the fabrication of free-standing silicon nanowires. The intense research concerning the fabrication of silicon nanowires has led to single crystalline nanowires with diameters of only a few nanometers. The hope that drove these intense research efforts where to find efficient photonic properties in these quantized systems. In the first part of this work detailed theoretical investigations are presented for the commonly observed ([111] and [11 anti 2]) representatives of free-standing and for the most frequently discussed ([001]) silicon nanowires not (so far) observed as free standing wires. Using density functional theory in the local density approximation the electronic properties as well as the structural changes due to the reduced dimensionality of silicon nanowires are calculated and discussed. The comparison to recent experimental, scanning tunneling experiments reveal a fundamental discrepancy between the calculated band structures and experimental findings. With our results we are able to explain these differences. Raman investigations on silicon nanowires where in a state of controversial discussion about the origin of observed red shifted spectra. Various contributions like quantum confinement, photo excitation and thermal effects where discussed. The second part of this thesis contributes to this discussion, with detailed laser power dependent Raman spectroscopic

  15. Thermal stability of silicon nanowires:atomistic simulation study

    Institute of Scientific and Technical Information of China (English)

    Liu Wen-Liang; Zhang Kai-Wang; Zhong Jian-Xin

    2009-01-01

    Using the Stillinger-Weber (SW) potential model, we investigate the thermal stability of pristine silicon nanowires based on classical molecular dynamics (MD) simulations. We explore the structural evolutions and the Lindemann indices of silicon nanowires at different temperatures in order to unveil atomic-level melting behaviour of silicon nanowires.The simulation results show that silicon nanowires with surface reconstructions have higher thermal stability than those without surface reconstructions, and that silicon nanowires with perpendicular dimmer rows on the two (100) surfaces have somewhat higher thermal stability than nanowires with parallel dimmer rows on the two (100) surfaces. Furthermore, the melting temperature of silicon nanowires increases as their diameter increases and reaches a saturation value close to the melting temperature of bulk silicon. The value of the Lindemann index for melting silicon nanowires is 0.037.

  16. Broadband Nonlinear Signal Processing in Silicon Nanowires

    DEFF Research Database (Denmark)

    Yvind, Kresten; Pu, Minhao; Hvam, Jørn Märcher;

    The fast non-linearity of silicon allows Tbit/s optical signal processing. By choosing suitable dimensions of silicon nanowires their dispersion can be tailored to ensure a high nonlinearity at power levels low enough to avoid significant two-photon abso We have fabricated low insertion...

  17. Hydrogen passivation of silicon nanowire structures

    Science.gov (United States)

    Aouida, S.; Benabderrahmane Zaghouani, R.; Bachtouli, N.; Bessais, B.

    2016-05-01

    In this work, we focus on hydrogen passivation of silicon nanowire structures (SiNWs) obtained by metal assisted chemical etching (MACE) intended to be used in silicon-based solar cells. SiNWs present high surface defects density causing the minority carrier lifetime reduction. Our results show that hydrogen passivation of SiNWs ameliorates minority carrier lifetime by reducing the dangling bonds and then the surface recombination velocity. This enhancement is limited by SiNWs distribution.

  18. Silicon nanowire field-effect chemical sensor

    NARCIS (Netherlands)

    Chen, Songyue

    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 nove

  19. Growth of Silicon Nanowires by Heating Si Substrate

    Institute of Scientific and Technical Information of China (English)

    邢英杰; 奚中和; 俞大鹏; 杭青岭; 严涵斐; 冯孙齐; 薛增泉

    2002-01-01

    Amorphous silicon nanowires were prepared by heating an Si substrate at high temperatures using an Ni (or Au) catalyst. The nanowires have a diameter of 10 - 40nm and a length of up to several tens of micrometres.Unlike the well-known vapour-liquid-solid mechanism, a solid-liquid-solid mechanism appeared to control the nanowire growth. The heating process had a strong influence on the growth of silicon nanowires. It was found that ambient gas was necessary to grow nanowires. This method can be used to prepare other kinds of nanowires.

  20. Fabrication and properties of silicon carbide nanowires

    Science.gov (United States)

    Shim, Hyun Woo

    2008-12-01

    Silicon carbide (SiC), with excellent electrical, thermal, and mechanical properties, is a promising material candidate for future devices such as high-temperature electronics and super-strong lightweight structures. Combined with superior intrinsic properties, the nanomaterials of SiC show further advantages thanks to nanoscale effects. This thesis reports the growth mechanism, the self-integration, and the friction of SiC nanowires. The study involves nanowires fabrication using thermal evaporation, structure characterization using electron microscopy, friction measurement, and theoretical modeling. The study on nanowire growth mechanism requires understanding of the surfaces and interfaces of nanowire crystal. The catalyzed growth of SiC nanowires involves interfaces between source vapor, catalytic liquid, and nanowire solid. Our experimental observation includes the periodical twinning in a faceted SiC nanowire and three stage structure transitions during the growth. The proposed theoretical model shows that such phenomenon is the result of surface energy minimization process during the catalytic growth. Surface interactions also exist between nanowires, leading to their self-integration. Our parametric growth study reveals novel self-integration of SiC-SiO 2 core-shell nanowires as a result of SiO2 joining. Attraction between nanowires through van der Waals force and enhanced SiO2 diffusion at high temperature transform individual nanowires to the integrated nanojunctions, nanocables, and finally nanowebs. We also show that such joining process becomes effective either during growth or by annealing. The solid friction is a result of the interaction between two solid surfaces, and it depends on the adhesion and the deformation of two contacting solids among other factors. Having strong adhesion as shown from gecko foot-hairs, nanostructured materials should also have strong friction; this study is the first to investigate friction of nanostructures under

  1. Structural, electronic, and transport properties of silicon nanowires

    OpenAIRE

    Rurali, Riccardo

    2009-01-01

    In this paper we review the theory of silicon nanowires. We focus on nanowires with diameters below 10 nm, where quantum effects become important and the properties diverge significantly from those of bulk silicon. These wires can be efficiently treated within electronic structure simulation methods and will be among the most important functional blocks of future nanoelectronic devices. Firstly, we review the structural properties of silicon nanowires, emphasizing the close connection between...

  2. Preparation and testing of silicon nanowires

    Czech Academy of Sciences Publication Activity Database

    Müller, Martin; Kočka, Jan; El Gohary, H.G.; Stuchlík, Jiří; Stuchlíková, The-Ha; Hruška, Karel; Rezek, Bohuslav; Ledinský, Martin; Fejfar, Antonín

    2014-01-01

    Roč. 92, 7-8 (2014), s. 819-821. ISSN 0008-4204 R&D Projects: GA MPO FR-TI2/736; GA ČR GA13-25747S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : silicon * nanowires * deposition * gold * VLS Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.964, year: 2014

  3. Laser direct synthesis of silicon nanowire field effect transistors

    International Nuclear Information System (INIS)

    We demonstrate a single-step, laser-based technique to fabricate silicon nanowire field effect transistors. Boron-doped silicon nanowires are synthesized using a laser-direct-write chemical vapor deposition process, which can produce nanowires as small as 60 nm, far below the diffraction limit of the laser wavelength of 395 nm. In addition, the method has the advantages of in situ doping, catalyst-free growth, and precise control of nanowire position, orientation, and length. Silicon nanowires are directly fabricated on an insulating surface and ready for subsequent device fabrication without the need for transfer and alignment, thus greatly simplifying device fabrication processes. Schottky barrier nanowire field effect transistors with a back-gate configuration are fabricated from the laser-direct-written Si nanowires and electrically characterized. (paper)

  4. Strain in silicon nanowire beams

    Science.gov (United States)

    Ureña, Ferran; Olsen, Sarah H.; Šiller, Lidija; Bhaskar, Umesh; Pardoen, Thomas; Raskin, Jean-Pierre

    2012-12-01

    In this work, strain in silicon free standing beams loaded in uniaxial tension is experimentally and theoretically investigated for strain values ranging from 0 to 3.6%. The fabrication method allows multiple geometries (and thus strain values) to be processed simultaneously on the same wafer while being studied independently. An excellent agreement of strain determined by two non-destructive characterization techniques, Raman spectroscopy and mechanical displacement using scanning electron microscopy (SEM) markers, is found for all the sample lengths and widths. The measured data also show good agreement with theoretical predictions of strain based upon continuum mechanical considerations, giving validity to both measurement techniques for the entire range of strain values. The dependence of Young's modulus and fracture strain on size has also been analyzed. The Young's modulus is determined using SEM and compared with that obtained by resonance-based methods. Both methods produced a Young's modulus value close to that of bulk silicon with values obtained by resonance-based methods being slightly lower. Fracture strain is analyzed in 40 sets of samples with different beam geometries, yielding values up to 3.6%. The increase in fracture strain with decreasing beam width is compared with previous reports. Finally, the role of the surface on the mechanical properties is analyzed using UV and visible lasers having different penetration depths in silicon. The observed dependence of Raman shift on laser wavelength is used to assess the thermal conductivity of deformed silicon.

  5. Magnetic resonance characterization of silicon nanowires

    Science.gov (United States)

    Fanciulli, Marco; Belli, Matteo; Vellei, Antonio; Canevali, Carmen; Rotta, Davide; Paleari, Stefano; Basini, Martina

    2012-02-01

    Silicon nanowires (SiNWs) have been extensively investigated in the last decades. The interest in these nanostructures stems from both fundamental and applied research motivations. The functional properties of one- and zero-dimensional silicon structures are significantly different, at least below a certain critical dimension, from those well known in the bulk. The key and peculiar functional properties of SiNWs find applications in nanoelectronics, classical and quantum information processing and storage, optoelectronics, photovoltaics, thermoelectric, battery technology, nano-biotechnology, and neuroelectronics. We report our work on the characterization by continuous wave (CW) and pulse electron spin resonance (CW, FT-EPR) and electrically detected magnetic resonance (EDMR) measurements of silicon nanowires (SiNWs) produced by different top-down processes. SiNWs were fabricated starting from SOI wafers using standard e-beam lithography and anisotropic wet etching or by metal-assisted chemical etching. Further oxidation was used to reduce the wire cross section. Different EDMR implementations were used to address the electronic wave function of donors (P, As) and to characterize point defects at the SiNWs/SiO2 interface.

  6. Preparation and Characterization of Amorphous Silicon Oxide Nanowires

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large-scale amorphous silicon nanowires (SiNWs) with a diameter about 100 nm and a length of dozens of micrometers on silicon wafers were synthesized by thermal evaporation of silicon monoxide (SiO).Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the silicon nanowires are smooth.Selected area electron diffraction (SAED) shows that the silicon nanowires are amorphous and energy-dispersive X-ray spectroscopy (EDS) indicates that the nanowires have the composition of Si and O elements in an atomic ratio of 1:2, their composition approximates that of SiO2.SiO is considered to be used as a Si sources to produce SiNWs.We conclude that the growth mechanism is closely related to the defect structure and silicon monoxide followed by growth through an oxide-assisted vapor-solid reaction.

  7. Biodegradable porous silicon barcode nanowires with defined geometry

    OpenAIRE

    Chiappini, Ciro; Liu, Xuewu; Fakhoury, Jean Raymond; Ferrari, Mauro

    2010-01-01

    Silicon nanowires are of proven importance in diverse fields such as energy production and storage, flexible electronics, and biomedicine due to the unique characteristics emerging from their one-dimensional semiconducting nature and their mechanical properties. Here we report the synthesis of biodegradable porous silicon barcode nanowires by metal assisted electroless etch of single crystal silicon with resistivity ranging from 0.0008 Ω-cm to 10 Ω-cm. We define the geometry of the barcode na...

  8. Facile Pyrolytic Synthesis of Silicon Nanowires.

    Science.gov (United States)

    Chan, Joo C; Tran, Hoang; Pattison, James W; Rananavare, Shankar B

    2010-10-01

    One-dimensional nanostructures such as silicon nanowires (SiNW) are attractive candidates for low power density electronic and optoelectronic devices including sensors. A new simple method for SiNW bulk synthesis[1, 2] is demonstrated in this work, which is inexpensive and uses low toxicity materials, thereby offering a safe, energy efficient and green approach. The method uses low flammability liquid phenylsilanes, offering a safer avenue for SiNW growth compared with using silane gas. A novel, duo-chamber glass vessel is used to create a low-pressure environment where SiNWs are grown through vapor-liquid-solid mechanism using gold nanoparticles as a catalyst. The catalyst decomposes silicon precursor vapors of diphenylsilane and triphenylsilane and precipitates single crystal SiNWs, which appear to grow parallel to the substrate surface. This opens up possibilities for synthesizing nano-junctions amongst wires which is important for the grid architecture of nanoelectronics proposed by Likharev[3]. Even bulk synthesis of SiNW is feasible using sacrificial substrates such as CaCO(3) that can be dissolved post-synthesis. Furthermore, by dissolving appropriate dopants in liquid diphenylsilane, a controlled doping of the nanowires is realized without the use of toxic gases and expensive mass flow controllers. Upon boron doping, we observe a characteristic red shift in photoluminescence spectra. In summary, an inexpensive and versatile method for SiNW is presented that makes these exotic materials available to any lab at low cost. PMID:20711489

  9. Increasing the efficiency of polymer solar cells by silicon nanowires

    International Nuclear Information System (INIS)

    Silicon nanowires have been introduced into P3HT:[60]PCBM solar cells, resulting in hybrid organic/inorganic solar cells. A cell efficiency of 4.2% has been achieved, which is a relative improvement of 10% compared to a reference cell produced without nanowires. This increase in cell performance is possibly due to an enhancement of the electron transport properties imposed by the silicon nanowires. In this paper, we present a novel approach for introducing the nanowires by mixing them into the polymer blend and subsequently coating the polymer/nanowire blend onto a substrate. This new onset may represent a viable pathway to producing nanowire-enhanced polymer solar cells in a reel to reel process.

  10. Scattering cross section of metal catalyst atoms in silicon nanowires

    DEFF Research Database (Denmark)

    Markussen, Troels; Rurali, R.; Cartoixa, X.;

    2010-01-01

    A common technique to fabricate silicon nanowires is to use metal particles (e.g., Au, Ag, Cu, Al) to catalyze the growth reaction. As a consequence, the fabricated nanowires contain small concentrations of these metals as impurities. In this work we investigate the effect of the metallic impurit...

  11. Silicon nanowire synthesis by a vapor-liquid-solid approach

    Science.gov (United States)

    Mao, Aaron; Ng, H. T.; Nguyen, Pho; McNeil, Melanie; Meyyappan, M.

    2005-01-01

    Synthesis of silicon nanowires is studied by using a vapor-liquid-solid growth technique. Silicon tetrachloride reduction with hydrogen in the gas phase is used with gold serving as catalyst to facilitate growth. Only a narrow set of conditions of SiCl4 concentration and temperature yield straight nanowires. High concentrations and temperatures generally result in particulates, catalyst coverage and deactivation, and coatinglike materials.

  12. Global optimization of silicon nanowires for efficient parametric processes

    DEFF Research Database (Denmark)

    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....

  13. SiC nanowires synthesized from graphene and silicon vapors

    Science.gov (United States)

    Weichenpei, Luo; Gong-yi, Li; Zengyong, Chu; Tianjiao, Hu; Xiaodong, Li; Xuefei, Zhang

    2016-04-01

    The preparation of silicon carbide (SiC) nanowires is basically important for its potential applications in nanodevices, nanocomposites, etc. In the present work, a simple route was reported to synthesize SiC nanowires by heating commercial graphene with silicon vapors and no catalyst. Characterization by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, electron energy scattering, X-ray diffraction, and Raman dispersive spectrum demonstrates the products are composed of β-SiC crystal. The SiC nanowires have the average diameter of about 50 nm and length of tens of micrometers. The vapor-solid mechanism was employed to interpret the SiC nanowires growth. Gaseous SiO which was produced by the reaction of Si powders with its surface oxidation reacted with the solid graphene to form SiC crystal nuclei. And SiC crystal nuclei would act as active sites for further growing into nanowires.

  14. Synthesis and characterization of germanium nanowires and germanium/silicon radially heterostructured nanowires

    Science.gov (United States)

    Goldthorpe, Irene Anne

    Semiconductor nanowires offer new opportunities to study physical phenomena in low-dimensional nanostructures. They also possess technologically useful properties for applications in electronics, optics, sensing, and thermoelectrics. Germanium nanowires are of particular interest, because of germanium's compatibility with standard silicon integrated circuit fabrication processes, its high electronic carrier mobilities, and the low temperature required for germanium nanowire growth. In this work, epitaxially-aligned germanium nanowires are grown on silicon substrates by chemical vapor deposition through the vapor-liquid-solid mechanism. Uniform nanowire diameters between 5 and 50 nm are obtained through the use of monodisperse gold colloids as catalysts. The crystallographic orientation of the nanowires, their strain, and their heteroepitaxial relationship with the substrate are characterized with transmission electron microscopy (TEM) and x-ray diffraction (XRD). A process for removing the gold catalysts from the tips of the germanium nanowires is demonstrated. Silicon shells are then heteroepitaxially deposited around the wires to fabricate radial heterostructures. These shells passivate the germanium nanowire surface, create electronic band offsets to confine holes away the surface where they can scatter or recombine, and induce strain which could allow for the engineering of properties such as band gap and carrier mobilities. However, analogous to planar heteroepitaxy, surface roughening and misfit dislocations can relax this strain. The effects of coaxial dimensions on strain relaxation in these structures are analyzed quantitatively by TEM and synchrotron XRD, and these results are related to continuum elasticity models. Lessons learned generated two successful strategies for synthesizing coherent core-shell nanowires with large misfit strain: chlorine surface passivation and growth of nanowires with low-energy sidewall facets. Both approaches avoid the strain

  15. Plasmon-loss imaging of chains of crystalline-silicon nanospheres and silicon nanowires

    Science.gov (United States)

    Kohno; Takeda; Tanaka

    2000-01-01

    Nanostructures in chains of crystalline-silicon nanospheres and silicon nanowires were investigated using energy-filtered transmission electron microscopy (TEM). Observation of the shape of the silicon nanospheres in the chains provided the direct evidence that the chains were formed via the surface oxidation process, which may preferentially work at the necks. The diverse nanostructures in silicon nanowires were revealed, and we found smooth-shaped wires which have periodically modulated silicon cores. Nanostructures in wire-chain transition regions were also investigated for the first time. The wire-chain transition is not a simple junction of a silicon nanowire and a chain of silicon nanospheres, but has a periodically modulated silicon core in the wire region near the transition position. PMID:11108050

  16. All-(111) surface silicon nanowires: selective functionalization for biosensing applications

    NARCIS (Netherlands)

    Masood, M.N.; Chen, S.; Carlen, E.T.; Berg, van den A.

    2010-01-01

    e demonstrate the utilization of selective functionalization of carbon-silicon (C-Si) alkyl and alkenyl monolayers covalently linked to all-(111) surface silicon nanowire (Si-NW) biosensors. Terminal amine groups on the functional monolayer surfaces were used for conjugation of biotin n-hydroxysucci

  17. Silicon and silicide nanowires applications, fabrication, and properties

    CERN Document Server

    Tu, King-Ning

    2013-01-01

    This book comprises theoretical and experimental analysis of various properties of silicon nanocrystals, research methods and preparation techniques, and some promising applications. It comprises nine chapters. The first three are based on processing, the next three on properties, and the last three on applications of nanowires of silicon and silicides.

  18. Silicon oxide nanowires: facile and controlled large area fabrication of vertically oriented silicon oxide nanowires for photoluminescence and sensor applications.

    Science.gov (United States)

    Alabi, Taiwo R; Yuan, Dajun; Bucknall, David; Das, Suman

    2013-09-25

    We describe a technique for the fabrication of dense and patterned arrays of aligned silicon oxide nanowires for applications in surface modification, optoelectronic, and electromechanical based devices. Conventional techniques for the fabrication of silicon oxide nanowires based on the vapor-liquid-solid (VLS) chemical vapor deposition (CVD) processes involve the use of high temperatures and catalysts. We demonstrate a technique that extends the use of a plasma thermal reactive ion etching for the fabrication of aligned silicon oxide nanowires with aspect ratios extending up to 20 and lengths exceeding 1 μm. The process incorporates phase separated PS-b-P4VP block copolymer loaded with an iron salt. The iron salt preferentially segregates into the P4VP layer and during an O2 etch is not removed but forms a hexagonally packed array on the silicon oxide substrate. Further etching with CHF3/O2 gas mixture over time can generate nanodots, to nanopillars, and then nanowires of silicon oxide. The photoluminescence property of the as-fabricated nanowire arrays as well as the parasitic ferromagnetic effect from the iron oxide-tipped section of the wires resulting in coalescence under an scanning electron microscope (SEM) are demonstrated. This technique is simpler compared to existing VLS fabrication approaches and can be used for the direct fabrication of patterned arrays of nanowires when a laser interference ablation step is incorporated into the fabrication procedure. PMID:23915216

  19. True reference nanosensor realized with silicon nanowires.

    Science.gov (United States)

    Tarasov, A; Wipf, M; Bedner, K; Kurz, J; Fu, W; Guzenko, V A; Knopfmacher, O; Stoop, R L; Calame, M; Schönenberger, C

    2012-06-26

    Conventional gate oxide layers (e.g., SiO(2), Al(2)O(3), or HfO(2)) in silicon field-effect transistors (FETs) provide highly active surfaces, which can be exploited for electronic pH sensing. Recently, great progress has been achieved in pH sensing using compact integrateable nanowire FETs. However, it has turned out to be much harder to realize a true reference electrode, which--while sensing the electrostatic potential--does not respond to the proton concentration. In this work, we demonstrate a highly effective reference sensor, a so-called reference FET, whose proton sensitivity is suppressed by as much as 2 orders of magnitude. To do so, the Al(2)O(3) surface of a nanowire FET was passivated with a self-assembled monolayer of silanes with a long alkyl chain. We have found that a full passivation can be achieved only after an extended period of self-assembling lasting several days at 80 °C. We use this slow process to measure the number of active proton binding sites as a function of time by a quantitative comparison of the measured nonlinear pH-sensitivities to a theoretical model (site-binding model). Furthermore, we have found that a partially passivated surface can sense small changes in the number of active binding sites reaching a detection limit of δN(s) ≈ 170 μm(-2) Hz(-1/2) at 10 Hz and pH 3. PMID:22631046

  20. Comparison of confinement characters between porous silicon and silicon nanowires

    International Nuclear Information System (INIS)

    Confinement character and its effects on photoluminescence (PL) properties are theoretically investigated and compared between porous silicon (p-Si) and silicon nanowires (Si-NWs). The method is based on the application of the tight-binding technique using the minimal sp3-basis set, including the second-nearest-neighbor interactions. The results show that the quantum confinement (QC) is not entirely controlled by the porosity, rather it is mainly affected by the average distance between pores (d). The p-Si is found to exhibit weaker confinement character than Si-NWs. The confinement energy of charge carriers decays against d exponentially for p-Si and via a power-law for Si-NWs. This latter type of QC is much stronger and is somewhat similar to the case of a single particle in a quantum box. The excellent fit to the PL data demonstrates that the experimental samples of p-Si do exhibit strong QC character and thus reveals the possibility of silicon clustering into nano-crystals and/or nanowires. Furthermore, the results show that the passivation of the surface dangling bonds by the hydrogen atoms plays an essential role in preventing the appearance of gap states and consequently enhances the optical qualities of the produced structures. The oscillator strength (OS) is found to increase exponentially with energy in Si-NWs confirming the strong confinement character of carriers. Our theoretical findings suggest the existence of Si nanocrystals (Si-NCs) of sizes 1-3 nm and/or Si-NWs of cross-sectional sizes in the 1-3 nm range inside the experimental p-Si samples. The experimentally-observed strong photoluminescence from p-Si should be in favor of an exhibition of 3D-confinement character. The favorable comparison of our theoretical results with the experimental data consolidates our above claims. -- Highlights: → Tight-binding is used to study quantum-confinement (QC) effects in p-Si and Si-NWs. → QC is not entirely controlled by the porosity but also by the d

  1. A deep etching mechanism for trench-bridging silicon nanowires

    Science.gov (United States)

    Tasdemir, Zuhal; Wollschläger, Nicole; Österle, Werner; Leblebici, Yusuf; Erdem Alaca, B.

    2016-03-01

    Introducing a single silicon nanowire with a known orientation and dimensions to a specific layout location constitutes a major challenge. The challenge becomes even more formidable, if one chooses to realize the task in a monolithic fashion with an extreme topography, a characteristic of microsystems. The need for such a monolithic integration is fueled by the recent surge in the use of silicon nanowires as functional building blocks in various electromechanical and optoelectronic applications. This challenge is addressed in this work by introducing a top-down, silicon-on-insulator technology. The technology provides a pathway for obtaining well-controlled silicon nanowires along with the surrounding microscale features up to a three-order-of-magnitude scale difference. A two-step etching process is developed, where the first shallow etch defines a nanoscale protrusion on the wafer surface. After applying a conformal protection on the protrusion, a deep etch step is carried out forming the surrounding microscale features. A minimum nanowire cross-section of 35 nm by 168 nm is demonstrated in the presence of an etch depth of 10 μm. Nanowire cross-sectional features are characterized via transmission electron microscopy and linked to specific process steps. The technology allows control on all dimensional aspects along with the exact location and orientation of the silicon nanowire. The adoption of the technology in the fabrication of micro and nanosystems can potentially lead to a significant reduction in process complexity by facilitating direct access to the nanowire during surface processes such as contact formation and doping.

  2. Surface functionalization of HF-treated silicon nanowires

    Indian Academy of Sciences (India)

    Ming-Wang Shao; Hong Wang; Yan Fu; Jun Hua; Dorothy-Duo-Duo Ma

    2009-05-01

    Versatile methods were employed to investigate the chemical reactivity of hydrogenterminated surface of silicon nanowires. The experimental results showed that coupling reaction took place when silicon nanowires reacted with 2,2,2-trifluoroethyl acrylate, and reductive deposition reaction occurred in the presence of inorganic salt such as HgCl2, and also co-reduction reaction took place in a solution containing both AuCl3 and PdCl2. The possible reaction mechanisms were studied and this study would be expected to favour the homogeneity, selectivity, reproducibility, and stability of SiNW devices or sensors.

  3. Microspheres for the Growth of Silicon Nanowires via Vapor-Liquid-Solid Mechanism

    Directory of Open Access Journals (Sweden)

    Arancha Gómez-Martínez

    2014-01-01

    Full Text Available Silicon nanowires have been synthesized by a simple process using a suitable support containing silica and carbon microspheres. Nanowires were grown by thermal chemical vapor deposition via a vapor-liquid-solid mechanism with only the substrate as silicon source. The curved surface of the microsized spheres allows arranging the gold catalyst as nanoparticles with appropriate dimensions to catalyze the growth of nanowires. The resulting material is composed of the microspheres with the silicon nanowires attached on their surface.

  4. Photoluminescence Properties of Silicon Nanowires and Carbon Nanotube-Silicon Nanowire Composite Arrays

    Institute of Scientific and Technical Information of China (English)

    李梦轲; 陆梅; 孔令斌; 王成伟; 郭新勇; 力虎林

    2002-01-01

    Composite arrays of multi-wall carbon nanotubes (MWNTs) and silicon nanowires (SiNWs) are fabricated by means of the chemical vapour deposition method in porous anodic aluminium oxide (AAO) templates. The results of the scanning electron microscopy, high-resolution transmission electron microscopy, and transmission electron microscopy have shown that SiNWs are successful nested or filled in the hollow cavities of synthesized MWNT arrays in AAO templates to form MWNT-SiNW composite arrays. The photoluminescence (PL) intensity degradation and a blueshift of PL peak position, usually created from the chemical instability of the SiNW surfaces, are decreased and eliminated clearly in the composite arrays. The composite arrays of MWNTs-SiNWs exhibit more enhanced intensity and stability of PL performance than the SiNW arrays deposited in AAO templates.

  5. Raman spectra of silicon carbide small particles and nanowires

    Science.gov (United States)

    Wieligor, Monika; Wang, Yuejian; Zerda, T. W.

    2005-04-01

    Two manufacturing protocols of silicon carbide (SiC) nanowires are discussed. The Raman spectra of produced SiC nanowires are compared with spectra of SiC powders of various grain sizes. The temperature and pressure dependence of the Raman spectra for powders is similar to that of bulk crystals, but is different for nanowires. Frequency shifts, band broadenings and the presence of shoulders are discussed in terms of crystal size, character of defects and their population. The concentration of defects in synthesized nanowires depends on the sintering method. Raman intensity enhancement of the LO phonon was observed when the wavelength of the excitation laser was changed from 780 to 514 nm.

  6. Raman spectra of silicon carbide small particles and nanowires

    International Nuclear Information System (INIS)

    Two manufacturing protocols of silicon carbide (SiC) nanowires are discussed. The Raman spectra of produced SiC nanowires are compared with spectra of SiC powders of various grain sizes. The temperature and pressure dependence of the Raman spectra for powders is similar to that of bulk crystals, but is different for nanowires. Frequency shifts, band broadenings and the presence of shoulders are discussed in terms of crystal size, character of defects and their population. The concentration of defects in synthesized nanowires depends on the sintering method. Raman intensity enhancement of the LO phonon was observed when the wavelength of the excitation laser was changed from 780 to 514 nm

  7. Silicon nanowire networks for multi-stage thermoelectric modules

    International Nuclear Information System (INIS)

    Highlights: • Fabricated flexible single, double, and quadruple stacked Si thermoelectric modules. • Measured an enhanced power production of 27%, showing vertical stacking is scalable. • Vertically scalable thermoelectric module design of semiconducting nanowires. • Design can utilize either p or n-type semiconductors, both types are not required. • ΔT increases with thickness therefore power/area can increase as modules are stacked. - Abstract: We present the fabrication and characterization of single, double, and quadruple stacked flexible silicon nanowire network based thermoelectric modules. From double to quadruple stacked modules, power production increased 27%, demonstrating that stacking multiple nanowire thermoelectric devices in series is a scalable method to generate power by supplying larger temperature gradient. We present a vertically scalable multi-stage thermoelectric module design using semiconducting nanowires, eliminating the need for both n-type and p-type semiconductors for modules

  8. Reconfigurable quadruple quantum dots in a silicon nanowire transistor

    OpenAIRE

    Betz, A. C.; Tagliaferri, M. L. V.; Vinet, M.; Broström, M.; Sanquer, M.; Ferguson, A.J.; Gonzalez-Zalba, M. F.

    2016-01-01

    We present a novel reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consist of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired...

  9. Integrated freestanding single-crystal silicon nanowires: conductivity and surface treatment

    International Nuclear Information System (INIS)

    Integrated freestanding single-crystal silicon nanowires with typical dimension of 100 nm x 100 nm x 5 μm are fabricated by conventional 1:1 optical lithography and wet chemical silicon etching. The fabrication procedure can lead to wafer-scale integration of silicon nanowires in arrays. The measured electrical transport characteristics of the silicon nanowires covered with/without SiO2 support a model of Fermi level pinning near the conduction band. The I-V curves of the nanowires reveal a current carrier polarity reversal depending on Si-SiO2 and Si-H bonds on the nanowire surfaces.

  10. Rare earth silicide nanowires on silicon surfaces

    International Nuclear Information System (INIS)

    The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti Γ point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi2-monolayer and the Dy3Si5-multilayer on the Si(111) surface are investigated in comparison to the known ErSi2/Si(111) and Er3Si5/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the vector k parallel space is elliptical at the anti M points, while the hole pocket at the anti Γ point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas of the sample surface, which are oriented in the same

  11. Transport in Silicon Nanowires: Role of Radial Dopant Profile

    DEFF Research Database (Denmark)

    Markussen, Troels; Rurali, Riccardo; Jauho, Antti-Pekka;

    2008-01-01

    We consider the electronic transport properties of phosphorus (P) doped silicon nanowires (SiNWs). By combining ab initio density functional theory (DFT) calculations with a recursive Green's function method, we calculate the conductance distribution of up to 200 nm long SiNWs with different dist...

  12. Twisted ultrathin silicon nanowires: A possible torsion electromechanical nanodevice

    Science.gov (United States)

    Garcia, J. C.; Justo, J. F.

    2014-11-01

    Nanowires have been considered for a number of applications in nanometrology. In such a context, we have explored the possibility of using ultrathin twisted nanowires as torsion nanobalances to probe forces and torques at molecular level with high precision, a nanoscale system analogous to the Coulomb's torsion balance electrometer. In order to achieve this goal, we performed a first-principles investigation on the structural and electronic properties of twisted silicon nanowires, in their pristine and hydrogenated forms. The results indicated that wires with pentagonal and hexagonal cross-sections are the thinnest stable silicon nanostructures. Additionally, all wires followed a Hooke's law behavior for small twisting deformations. Hydrogenation leads to spontaneous twisting, but with angular spring constants considerably smaller than the ones for the respective pristine forms. We observed considerable changes on the nanowire electronic properties upon twisting, which allows to envision the possibility of correlating the torsional angular deformation with the nanowire electronic transport. This could ultimately allow a direct access to measurements on interatomic forces at molecular level.

  13. Characterization of functional biointerface on silicon nanowire MOSFET.

    Science.gov (United States)

    Lin, Shu-Ping; Liu, Mao-Chen; Chi, Tien-Yin; Kang, Yu-Shan

    2011-01-01

    Biointerface between biological organisms and electronic devices has attracted a lot of attention since a biocompatible and functional interface can revolutionize medical applications of bioelectronics. Here, we used 3-aminopropyl trimethoxysilane (APTMS) self-assembled monolayer (SAM) to modify the surface of nanowire-based metal-oxide-semiconductor field-effect transistors (NW-MOSFETs) for pH sensing and later creation of biointerface. Electrical measurement was utilized to first verify the sensing response of unmodified NW-MOSFETs and then examine pH sensing on APTMS modified NW-MOSFETs. A biointerface was then created by immobilizing polylysine, either poly-D-lysine (PDL) or poly-L-lysine (PLL), on APTMS modified NW-MOSFETs. This biointerface was characterized by electron spectroscopy for chemical analysis (ESCA), cell biocompatibility, and fluorescent images. The results of ESCA verified the amide bonding (CONH) between polylysine and APTMS modified surface. After PC12 cultured on polylysine-APTMS modified area, highly selective areas for cell growth were observed by fluorescent microscope. Analysis and improvement of selectively cell-growth biointerface on the NW-MOSFETs gave us an insight into future development of neuronal biosensors. PMID:22255403

  14. Performance Analysis of Silicon and Germanium Nanowire Transistor using Crystal Orientation and Oxide Thickness

    OpenAIRE

    P.Theres Mary; N.B. BALAMURUGAN

    2014-01-01

    Nanowire Transistors have attracted attention due to the probable high performance and excellent controllability of device current. In this paper, we investigate the performance analysis of nanowire transistors made of silicon and germanium materials. The nanowire transistor has a 3D distribution of electron density and electrostatic potential, therefore self-consistent 3D simulations are used. Nanowire (tool) is 3D Poisson self-consistent simulator which can study the 3D transport in nanowir...

  15. Local electrode atom probe analysis of silicon nanowires grown with an aluminum catalyst

    International Nuclear Information System (INIS)

    Local electrode atom probe (LEAP) tomography of Al-catalyzed silicon nanowires synthesized by the vapor–liquid–solid method is presented. The concentration of Al within the Al-catalyzed nanowire was found to be 2 × 1020 cm−3, which is higher than the expected solubility limit for Al in Si at the nanowire growth temperature of 550 °C. Reconstructions of the Al contained within the nanowire indicate a denuded region adjacent to the Al catalyst/Si nanowire interface, while Al clusters are distributed throughout the rest of the silicon nanowire. (paper)

  16. Silicon-nanowire based attachment of silicon chips for mouse embryo labelling.

    Science.gov (United States)

    Durán, S; Novo, S; Duch, M; Gómez-Martínez, R; Fernández-Regúlez, M; San Paulo, A; Nogués, C; Esteve, J; Ibañez, E; Plaza, J A

    2015-03-21

    The adhesion of small silicon chips to cells has many potential applications as direct interconnection of the cells to the external world can be accomplished. Hence, although some typical applications of silicon nanowires integrated into microsystems are focused on achieving a cell-on-a-chip strategy, we are interested in obtaining chip-on-a-cell systems. This paper reports the design, technological development and characterization of polysilicon barcodes featuring silicon nanowires as nanoscale attachment to identify and track living mouse embryos during their in vitro development. The chips are attached to the outer surface of the Zona Pellucida, the cover that surrounds oocytes and embryos, to avoid the direct contact between the chip and the embryo cell membrane. Two attachment methodologies, rolling and pushpin, which allow two entirely different levels of applied forces to attach the chips to living embryos, are evaluated. The former consists of rolling the mouse embryos over one barcode with the silicon nanowires facing upwards, while in the latter, the barcode is pushed against the embryo with a micropipette. The effect on in vitro embryo development and the retention rate related to the calculated applied forces are stated. Field emission scanning electron microscopy inspection, which allowed high-resolution imaging, also confirms the physical attachment of the nanowires with some of them piercing or wrapped by the Zona Pellucida and revealed extraordinary bent silicon nanowires. PMID:25609565

  17. Rare earth silicide nanowires on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Martina

    2008-11-10

    The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti {gamma} point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi{sub 2}-monolayer and the Dy{sub 3}Si{sub 5}-multilayer on the Si(111) surface are investigated in comparison to the known ErSi{sub 2}/Si(111) and Er{sub 3}Si{sub 5}/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the (vector)k {sub parallel} space is elliptical at the anti M points, while the hole pocket at the anti {gamma} point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas

  18. Enhanced diode performance in cadmium telluride–silicon nanowire heterostructures

    International Nuclear Information System (INIS)

    Highlights: • Vertically well oriented Si nanowire arrays on Si wafer were synthesized. • Semiconductor CdTe thin film/Si nanowire devices were successfully fabricated. • Optoelectronic properties of the fabricated devices were investigated. • Enhanced electrical and diode properties for the devices were observed. • The devices exhibited strong photosensitivity in near infrared region. - Abstract: We report on the structural and optoelectronic characteristics and photodetection properties of cadmium telluride (CdTe) thin film/silicon (Si) nanowire heterojunction diodes. A simple and cost-effective metal-assisted etching (MAE) method is applied to fabricate vertically oriented Si nanowires on n-type single crystalline Si wafer. Following the nanowire synthesis, CdTe thin films are directly deposited onto the Si nanowire arrays through RF magnetron sputtering. A comparative study of X-ray diffraction (XRD) and Raman spectroscopy shows the improved crystallinity of the CdTe thin films deposited onto the Si nanowires. The fabricated nanowire based heterojunction devices exhibit remarkable diode characteristics, enhanced optoelectronic properties and photosensitivity in comparison to the planar reference device. The electrical measurements revealed that the diodes have a well-defined rectifying behavior with a superior rectification ratio of 105 at ±5 V and a relatively small ideality factor of n = 1.9 with lower reverse leakage current and series resistance at room temperature in dark condition. Moreover, an open circuit voltage of 120 mV is also observed under illumination. Based on spectral photoresponsivity measurements, the nanowire based device exhibits a distinct responsivity (0.35–0.5 A W−1) and high detectivity (6 × 1012−9 × 1012 cm Hz1/2 W−1) in near-infrared wavelength region. The enhanced device performance and photosensitivity is believed to be due to three-dimensional nature of the interface between the CdTe thin film and the Si

  19. Enhanced diode performance in cadmium telluride–silicon nanowire heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Akgul, Funda Aksoy, E-mail: fundaaksoy01@gmail.com [Department of Physics, Nigde University, 51240 Nigde (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Akgul, Guvenc, E-mail: guvencakgul@gmail.com [Bor Vocational School, Nigde University, 51700 Nigde (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Gullu, Hasan Huseyin [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Unalan, Husnu Emrah [Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Turan, Rasit [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey)

    2015-09-25

    Highlights: • Vertically well oriented Si nanowire arrays on Si wafer were synthesized. • Semiconductor CdTe thin film/Si nanowire devices were successfully fabricated. • Optoelectronic properties of the fabricated devices were investigated. • Enhanced electrical and diode properties for the devices were observed. • The devices exhibited strong photosensitivity in near infrared region. - Abstract: We report on the structural and optoelectronic characteristics and photodetection properties of cadmium telluride (CdTe) thin film/silicon (Si) nanowire heterojunction diodes. A simple and cost-effective metal-assisted etching (MAE) method is applied to fabricate vertically oriented Si nanowires on n-type single crystalline Si wafer. Following the nanowire synthesis, CdTe thin films are directly deposited onto the Si nanowire arrays through RF magnetron sputtering. A comparative study of X-ray diffraction (XRD) and Raman spectroscopy shows the improved crystallinity of the CdTe thin films deposited onto the Si nanowires. The fabricated nanowire based heterojunction devices exhibit remarkable diode characteristics, enhanced optoelectronic properties and photosensitivity in comparison to the planar reference device. The electrical measurements revealed that the diodes have a well-defined rectifying behavior with a superior rectification ratio of 10{sup 5} at ±5 V and a relatively small ideality factor of n = 1.9 with lower reverse leakage current and series resistance at room temperature in dark condition. Moreover, an open circuit voltage of 120 mV is also observed under illumination. Based on spectral photoresponsivity measurements, the nanowire based device exhibits a distinct responsivity (0.35–0.5 A W{sup −1}) and high detectivity (6 × 10{sup 12}−9 × 10{sup 12} cm Hz{sup 1/2} W{sup −1}) in near-infrared wavelength region. The enhanced device performance and photosensitivity is believed to be due to three-dimensional nature of the interface between

  20. Synthesis and Photoluminescence Property of Silicon Carbide Nanowires Via Carbothermic Reduction of Silica

    OpenAIRE

    Luo Xiaogang; Ma Wenhui; Zhou Yang; Liu Dachun; Yang Bin; Dai Yongnian

    2009-01-01

    Abstract Silicon carbide nanowires have been synthesized at 1400 °C by carbothermic reduction of silica with bamboo carbon under normal atmosphere pressure without metallic catalyst. X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy and Fourier transformed infrared spectroscopy were used to characterize the silicon carbide nanowires. The results show that the silicon carbide nanowires have a core–shell structure and gr...

  1. Top-down silicon microcantilever with coupled bottom-up silicon nanowire for enhanced mass resolution

    International Nuclear Information System (INIS)

    A stepped cantilever composed of a bottom-up silicon nanowire coupled to a top-down silicon microcantilever electrostatically actuated and with capacitive or optical readout is fabricated and analyzed, both theoretically and experimentally, for mass sensing applications. The mass sensitivity at the nanowire free end and the frequency resolution considering thermomechanical noise are computed for different nanowire dimensions. The results obtained show that the coupled structure presents a very good mass sensitivity thanks to the nanowire, where the mass depositions take place, while also presenting a very good frequency resolution due to the microcantilever, where the transduction is carried out. A two-fold improvement in mass sensitivity with respect to that of the microcantilever standalone is experimentally demonstrated, and at least an order-of-magnitude improvement is theoretically predicted, only changing the nanowire length. Very close frequency resolutions are experimentally measured and theoretically predicted for a standalone microcantilever and for a microcantilever-nanowire coupled system. Thus, an improvement in mass sensing resolution of the microcantilever-nanowire stepped cantilever is demonstrated with respect to that of the microcantilever standalone. (paper)

  2. Nonlinear Optical Functions in Crystalline and Amorphous Silicon-on-Insulator Nanowires

    DEFF Research Database (Denmark)

    Baets, R.; Kuyken, B.; Liu, X.;

    2012-01-01

    Silicon-on-Insulator nanowires provide an excellent platform for nonlinear optical functions in spite of the two-photon absorption at telecom wavelengths. Work on both crystalline and amorphous silicon nanowires is reviewed, in the wavelength range of 1.5 to 2.5 µm.......Silicon-on-Insulator nanowires provide an excellent platform for nonlinear optical functions in spite of the two-photon absorption at telecom wavelengths. Work on both crystalline and amorphous silicon nanowires is reviewed, in the wavelength range of 1.5 to 2.5 µm....

  3. Approaching the ideal elastic strain limit in silicon nanowires.

    Science.gov (United States)

    Zhang, Hongti; Tersoff, Jerry; Xu, Shang; Chen, Huixin; Zhang, Qiaobao; Zhang, Kaili; Yang, Yong; Lee, Chun-Sing; Tu, King-Ning; Li, Ju; Lu, Yang

    2016-08-01

    Achieving high elasticity for silicon (Si) nanowires, one of the most important and versatile building blocks in nanoelectronics, would enable their application in flexible electronics and bio-nano interfaces. We show that vapor-liquid-solid-grown single-crystalline Si nanowires with diameters of ~100 nm can be repeatedly stretched above 10% elastic strain at room temperature, approaching the theoretical elastic limit of silicon (17 to 20%). A few samples even reached ~16% tensile strain, with estimated fracture stress up to ~20 GPa. The deformations were fully reversible and hysteresis-free under loading-unloading tests with varied strain rates, and the failures still occurred in brittle fracture, with no visible sign of plasticity. The ability to achieve this "deep ultra-strength" for Si nanowires can be attributed mainly to their pristine, defect-scarce, nanosized single-crystalline structure and atomically smooth surfaces. This result indicates that semiconductor nanowires could have ultra-large elasticity with tunable band structures for promising "elastic strain engineering" applications. PMID:27540586

  4. Synthesis and investigation of silicon carbide nanowires by HFCVD method

    Indian Academy of Sciences (India)

    S H MORTAZAVI; M GHORANNEVISS; M DADASHBABA; R ALIPOUR

    2016-08-01

    Silicon carbide (SiC) nanowire has been fabricated by hot filament chemical vapour deposition (HFCVD) mechanism in the temperature range of 600–800$^{\\circ}$C. Synthesis is performed under vacuum in the atmospheres of hexamethyldisiloxane/alcohol (HMDSO/C2H5OH) vapour and hydrogen (H$_2$) gas mixture. In this research dependence of SiC properties on temperature is discussed. Morphology and structural properties of SiC nanowire grown on glass substrate were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy diffraction spectrometer (EDX), and four-point probe (4PP). Also Mountains Map Premium (64-bit version)software is used to investigate morphological features of samples. In this context, the analysis of the motifs, depth histograms, statistical parameters, texture direction, fractal, and the peak count histograms of the nanostructuresurface of samples are carried out. According to analysis, SiC films had a good crystal quality without defects or low residual stress. We found that increasing substrate temperature increases silicon and oxygen doping amount. We also found that electrical resistivity and surface roughness increased by increasing substrate temperature. This study showed that SiC nanowires with high density grew on the free catalyst glass substrate, and the alignment of SiC nanowires decreased.

  5. Preparation of silica nanowires using porous silicon as Si source

    International Nuclear Information System (INIS)

    This very paper is focusing on the preparation of silica nano-wires via annealing porous silicon wafer at 1200 °C in H2 atmosphere and without the assistant metal catalysts. X-ray diffraction, X-ray energy dispersion spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy and selected area diffraction technology have been employed for characterizing the structures, the morphology and the chemical components of the nano-wires prepared, respectively. It is found that the diameter and the length of the nano-wires were about 100 nm and tens micron, respectively. Meanwhile, it is also necessary to be pointed out that silica NWs only formed in the cracks of porous wafers, where the stress induced both by the electro-chemical etching procedure for the porous silicon preparation and nanowires growth procedure is believed to be lower than that at Center of the island. Therefore, a stress-driven mechanism for the NWs growth model is proposed to explain these findings.

  6. Electric field effect thermoelectric transport in individual silicon and germanium/silicon nanowires

    Science.gov (United States)

    Brovman, Yuri M.; Small, Joshua P.; Hu, Yongjie; Fang, Ying; Lieber, Charles M.; Kim, Philip

    2016-06-01

    We have simultaneously measured conductance and thermoelectric power (TEP) of individual silicon and germanium/silicon core/shell nanowires in the field effect transistor device configuration. As the applied gate voltage changes, the TEP shows distinctly different behaviors while the electrical conductance exhibits the turn-off, subthreshold, and saturation regimes, respectively. At room temperature, peak TEP value of ˜300 μ V/K is observed in the subthreshold regime of the Si devices. The temperature dependence of the saturated TEP values is used to estimate the carrier doping of Si nanowires.

  7. Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires

    OpenAIRE

    Yang, Nuo; Zhang, Gang; Li, Baowen

    2007-01-01

    The thermal conductivity of silicon nanowires (SiNWs) is investigated by molecular dynamics (MD) simulation. It is found that the thermal conductivity of SiNWs can be reduced exponentially by isotopic defects at room temperature. The thermal conductivity reaches the minimum, which is about 27% of that of pure 28Si NW, when doped with fifty percent isotope atoms. The thermal conductivity of isotopic-superlattice structured SiNWs depends clearly on the period of superlattice. At a critical peri...

  8. Electronic Structure of Silicon Nanowires Matrix from Ab Initio Calculations.

    Science.gov (United States)

    Monastyrskii, Liubomyr S; Boyko, Yaroslav V; Sokolovskii, Bogdan S; Potashnyk, Vasylyna Ya

    2016-12-01

    An investigation of the model of porous silicon in the form of periodic set of silicon nanowires has been carried out. The electronic energy structure was studied using a first-principle band method-the method of pseudopotentials (ultrasoft potentials in the basis of plane waves) and linearized mode of the method of combined pseudopotentials. Due to the use of hybrid exchange-correlation potentials (B3LYP), the quantitative agreement of the calculated value of band gap in the bulk material with experimental data is achieved. The obtained results show that passivation of dangling bonds with hydrogen atoms leads to substantial transformation of electronic energy structure. At complete passivation of the dangling silicon bonds by hydrogen atoms, the band gap value takes the magnitude which substantially exceeds that for bulk silicon. The incomplete passivation gives rise to opposite effect when the band gap value decreases down the semimetallic range. PMID:26768147

  9. Growth of crystalline silicon nanowires on nickel-coated silicon wafer beneath sputtered amorphous carbon

    International Nuclear Information System (INIS)

    Growth of crystalline silicon nanowire of controllable diameter directly from Si wafer opens up another avenue for its application in solar cells and optical sensing. Crystalline Si nanowire can be directly grown from Si wafer upon rapid thermal annealing in the presence of the catalyst such as nickel (Ni). However, the accompanying oxidation immediately changes the crystalline Si nanowire to amorphous SiOx. In this study, amorphous carbon layer was sputtered to on top of the catalyst Ni layer to retard the oxidation. Scanning electron microscope, transmission electron microscope, Raman spectroscopy and X-ray photoelectron spectroscopy were employed to characterize the wires and oxidation process. A model was developed to explain the growth and oxidation process of the crystalline Si nanowire. - Highlights: ► Carbon was sputtered on nickel to retard the oxidation of silicon nanowires. ► Silicon core was controlled by carbon layer thickness and annealing duration. ► An oxidation-accompanying solid–liquid–solid growth mechanism was developed

  10. Automatic Release of Silicon Nanowire Arrays with a High Integrity for Flexible Electronic Devices

    OpenAIRE

    Luo Wu; Shuxin Li; Weiwei He; Dayong Teng; Ke Wang; Changhui Ye

    2014-01-01

    Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etc...

  11. Growth of Gold-assisted Gallium Arsenide Nanowires on Silicon Substrates via Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Ramon M. delos Santos

    2008-06-01

    Full Text Available Gallium arsenide nanowires were grown on silicon (100 substrates by what is called the vapor-liquid-solid (VLS growth mechanism using a molecular beam epitaxy (MBE system. Good quality nanowires with surface density of approximately 108 nanowires per square centimeter were produced by utilizing gold nanoparticles, with density of 1011 nanoparticles per square centimeter, as catalysts for nanowire growth. X-ray diffraction measurements, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy revealed that the nanowires are epitaxially grown on the silicon substrates, are oriented along the [111] direction and have cubic zincblende structure.

  12. Synthesis of silicon carbide nanowires by solid phase source chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    NI Jie; LI Zhengcao; ZHANG Zhengjun

    2007-01-01

    In this paper,we report a simple approach to synthesize silicon carbide(SiC)nanowires by solid phase source chemical vapor deposition(CVD) at relatively low temperatures.3C-SiC nanowires covered by an amorphous shell were obtained on a thin film which was first deposited on silicon substrates,and the nanowires are 20-80 am in diameter and several μm in length,with a growth direction of[200].The growth of the nanowires agrees well on vapor-liquid-solid (VLS)process and the film deposited on the substrates plays an important role in the formation of nanowires.

  13. Expanding the versatility of silicon carbide thin films and nanowires

    Science.gov (United States)

    Luna, Lunet

    Silicon carbide (SiC) based electronics and sensors hold promise for pushing past the limits of current technology to achieve small, durable devices that can function in high-temperature, high-voltage, corrosive, and biological environments. SiC is an ideal material for such conditions due to its high mechanical strength, excellent chemical stability, and its biocompatibility. Consequently, SiC thin films and nanowires have attracted interest in applications such as micro- and nano-electromechanical systems, biological sensors, field emission cathodes, and energy storage devices. However to fully realize SiC in such technologies, the reliability of metal contacts to SiC at high temperatures must be improved and the nanowire growth mechanism must be understood to enable strict control of nanowire crystal structure and orientation. Here, we present a novel metallization scheme, utilizing solid-state graphitization of SiC, to improve the long-term reliability of Pt/Ti contacts to polycrystalline n-type SiC films at high temperature. The metallization scheme includes an alumina protection layer and exhibits low, stable contact resistivity even after long-term (500 hr) testing in air at 450 ºC. We also report the crystal structure and growth mechanism of Ni-assisted silicon carbide nanowires using single-source precursor, methyltrichlorosilane. The effects of growth parameters, such as substrate and temperature, on the structure and morphology of the resulting nanowires will also be presented. Overall, this study provides new insights towards the realization of novel SiC technologies, enabled by advanced electron microscopy techniques located in the user facilities at the Molecular Foundry in Berkeley, California. This work was performed in part at the Molecular Foundry, supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  14. Catalyst-free growth of In(As)P nanowires on silicon

    OpenAIRE

    Mattila, M.; Hakkarainen, T.; Lipsanen, Harri; Jiang, H; Kauppinen, Esko I.

    2006-01-01

    The catalyst-free metal organic vapor phase epitaxialgrowth of In(As)P nanowires on silicon substrates is investigated using in situ deposited In droplets as seeds for nanowiregrowth. The thin substrate native oxide is found to play a crucial role in the nanowire formation. The structure of the nanowires is characterized by photoluminescence and electron microscopy measurements. The crystal structure of the InPnanowires is wurtzite with its c axis perpendicular to the nanowire axis. Adding ar...

  15. Dynamic Characterization and Impulse Response Modeling of Amplitude and Phase Response of Silicon Nanowires

    DEFF Research Database (Denmark)

    Cleary, Ciaran S.; Ji, Hua; Dailey, James M.;

    2013-01-01

    Amplitude and phase dynamics of silicon nanowires were measured using time-resolved spectroscopy. Time shifts of the maximum phase change and minimum amplitude as a function of pump power due to saturation of the free-carrier density were observed. A phenomenological impulse response model used to......, for silicon nanowires with lengths varying from 3.6 to 14.9 mm....

  16. Surface-Decorated Silicon Nanowires: A Route to High-ZT Thermoelectrics

    DEFF Research Database (Denmark)

    Markussen, Troels; Jauho, Antti-Pekka; Brandbyge, Mads

    2009-01-01

    Based on atomistic calculations of electron and phonon transport, we propose to use surface-decorated silicon nanowires for thermoelectric applications. Two examples of surface decorations are studied to illustrate the underlying ideas: nanotrees and alkyl functionalized silicon nanowires. For bo...

  17. Silicon nanowires for ultra-fast and ultrabroadband optical signal processing

    DEFF Research Database (Denmark)

    Ji, Hua; Hu, Hao; Pu, Minhao;

    2015-01-01

    In this paper, we present recent research on silicon nanowires for ultra-fast and ultra-broadband optical signal processing at DTU Fotonik. The advantages and limitations of using silicon nanowires for optical signal processing are revealed through experimental demonstrations of various optical...

  18. Structural and electrical properties of trimethylboron-doped silicon nanowires

    Science.gov (United States)

    Lew, Kok-Keong; Pan, Ling; Bogart, Timothy E.; Dilts, Sarah M.; Dickey, Elizabeth C.; Redwing, Joan M.; Wang, Yanfeng; Cabassi, Marco; Mayer, Theresa S.; Novak, Steven W.

    2004-10-01

    Trimethylboron (TMB) was investigated as a p-type dopant source for the vapor-liquid-solid growth of boron-doped silicon nanowires (SiNWs). The boron concentration in the nanowires was measured using secondary ion mass spectrometry and results were compared for boron-doping using TMB and diborane (B2H6) sources. Boron concentrations ranging from 1×1018 to 4×1019cm-3 were obtained by varying the inlet dopant/SiH4 gas ratio. TEM characterization revealed that the B2H6-doped SiNWs consisted of a crystalline core with a thick amorphous Si coating, while the TMB-doped SiNWs were predominantly single crystal even at high boron concentrations. The difference in structural properties was attributed to the higher thermal stability and reduced reactivity of TMB compared to B2H6. Four-point resistivity and gate-dependent conductance measurements were used to confirm p-type conductivity in the TMB-doped nanowires and to investigate the effect of dopant concentration on nanowire resistivity.

  19. Investigation of functionalized silicon nanowires by self-assembled monolayer

    Science.gov (United States)

    Hemed, Nofar Mintz; Convertino, Annalisa; Shacham-Diamand, Yosi

    2016-03-01

    The functionalization using self assembled monolayer (SAM) of silicon nanowires (SiNW) fabricated by plasma enhanced chemical vapor deposition (PECVD) is reported here. The SAM is being utilized as the first building block in the functionalization process. The morphology of the SiNW comprises a polycrystalline core wrapped by an hydrogenated amorphous silicon (α-Si:H) shell. Since most of the available methods for SAM verification and characterization are suitable only for flat substrates; therefore, in addition to the SiNW α-Si:H on flat samples were produced in the same system as the SiNWs. First we confirmed the SAM's presence on the flat α-Si:H samples using the following methods: contact angle measurement to determine the change in surface energy; atomic force microscopy (AFM) to determine uniformity and molecular coverage. Spectroscopic ellipsometry and X-ray reflectivity (XRR) were performed to measure SAM layer thickness and density. X-ray photoelectron spectroscopy (XPS) was applied to study the chemical states of the surface. Next, SiNW/SAM were tested by electrochemical impedance spectroscopy (EIS), and the results were compared to α-Si:H/SAM. The SAM electrical coverage on SiNW and α-Si:H was found to be ∼37% and ∼65 ± 3%, respectively. A model, based on transmission line theory for the nanowires is presented to explain the disparity in results between the nanowires and flat surface of the same materials.

  20. Self-heated silicon nanowires for high performance hydrogen gas detection

    International Nuclear Information System (INIS)

    Self-heated silicon nanowire sensors for high-performance, ultralow-power hydrogen detection have been developed. A top-down nanofabrication method based on well-established semiconductor manufacturing technology was utilized to fabricate silicon nanowires in wafer scale with high reproducibility and excellent compatibility with electronic readout circuits. Decoration of palladium nanoparticles onto the silicon nanowires enables sensitive and selective detection of hydrogen gas at room temperature. Self-heating of silicon nanowire sensors allows us to enhance response and recovery performances to hydrogen gas, and to reduce the influence of interfering gases such as water vapor and carbon monoxide. A short-pulsed heating during recovery was found to be effective for additional reduction of operation power as well as recovery characteristics. This self-heated silicon nanowire gas sensor will be suitable for ultralow-power applications such as mobile telecommunication devices and wireless sensing nodes. (paper)

  1. Synthesis and Photoluminescence Property of Silicon Carbide Nanowires Via Carbothermic Reduction of Silica.

    Science.gov (United States)

    Luo, Xiaogang; Ma, Wenhui; Zhou, Yang; Liu, Dachun; Yang, Bin; Dai, Yongnian

    2009-01-01

    Silicon carbide nanowires have been synthesized at 1400 degrees C by carbothermic reduction of silica with bamboo carbon under normal atmosphere pressure without metallic catalyst. X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy and Fourier transformed infrared spectroscopy were used to characterize the silicon carbide nanowires. The results show that the silicon carbide nanowires have a core-shell structure and grow along direction. The diameter of silicon carbide nanowires is about 50-200 nm and the length from tens to hundreds of micrometers. The vapor-solid mechanism is proposed to elucidate the growth process. The photoluminescence of the synthesized silicon carbide nanowires shows significant blueshifts, which is resulted from the existence of oxygen defects in amorphous layer and the special rough core-shell interface. PMID:20651911

  2. Synthesis and Photoluminescence Property of Silicon Carbide Nanowires Via Carbothermic Reduction of Silica

    Directory of Open Access Journals (Sweden)

    Luo Xiaogang

    2009-01-01

    Full Text Available Abstract Silicon carbide nanowires have been synthesized at 1400 °C by carbothermic reduction of silica with bamboo carbon under normal atmosphere pressure without metallic catalyst. X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy and Fourier transformed infrared spectroscopy were used to characterize the silicon carbide nanowires. The results show that the silicon carbide nanowires have a core–shell structure and grow along <111> direction. The diameter of silicon carbide nanowires is about 50–200 nm and the length from tens to hundreds of micrometers. The vapor–solid mechanism is proposed to elucidate the growth process. The photoluminescence of the synthesized silicon carbide nanowires shows significant blueshifts, which is resulted from the existence of oxygen defects in amorphous layer and the special rough core–shell interface.

  3. Heat Conductance is Strongly Anisotropic for Pristine Silicon Nanowires

    DEFF Research Database (Denmark)

    Markussen, Troels; Jauho, Antti-Pekka; Brandbyge, Mads

    2008-01-01

    We compute atomistically the heat conductance for ultrathin pristine silicon nanowires (SiNWs) with diameters ranging from 1 to 5 nm. The room temperature thermal conductance is found to be highly anisotropic: wires oriented along the 110 direction have 50−75% larger conductance than wires oriented...... along the 100 and 111 directions. We show that the anisotropies can be qualitatively understood and reproduced from the bulk phonon band structure. Ab initio density functional theory (DFT) is used to study the thinnest wires, but becomes computationally prohibitive for larger diameters, where we...... instead use the Tersoff empirical potential model (TEP). For the smallest wires, the thermal conductances obtained from DFT and TEP calculations agree within 10%. The presented results could be relevant for future phonon-engineering of nanowire devices....

  4. Optimized operation of silicon nanowire field effect transistor sensors

    International Nuclear Information System (INIS)

    Ion-sensitive field effect transistors have been advanced in recent years by utilizing silicon nanowires (Si-NWs), but establishing their optimized operation regime is an area of ongoing research. We propose a modified configuration of SiNWs in the form of a honeycomb structure to obtain high signal to noise ratio and high current stability. The low-frequency noise characteristics and the electrical stress are systematically considered for the optimization and compared against conventional SiNW devices. The operation voltage of the device severely affects the sensing stability; as the gate voltage is increased, the signal-to-noise ratio is enhanced, however, the stress effect becomes severe, and vice versa. The honeycomb nanowire structure shows enhanced noise characteristics in low voltage operation, proving to be an optimum solution for achieving highly stable sensor operation. (paper)

  5. Monolithically Integrated High-β Nanowire Lasers on Silicon.

    Science.gov (United States)

    Mayer, B; Janker, L; Loitsch, B; Treu, J; Kostenbader, T; Lichtmannecker, S; Reichert, T; Morkötter, S; Kaniber, M; Abstreiter, G; Gies, C; Koblmüller, G; Finley, J J

    2016-01-13

    Reliable technologies for the monolithic integration of lasers onto silicon represent the holy grail for chip-level optical interconnects. In this context, nanowires (NWs) fabricated using III-V semiconductors are of strong interest since they can be grown site-selectively on silicon using conventional epitaxial approaches. Their unique one-dimensional structure and high refractive index naturally facilitate low loss optical waveguiding and optical recirculation in the active NW-core region. However, lasing from NWs on silicon has not been achieved to date, due to the poor modal reflectivity at the NW-silicon interface. We demonstrate how, by inserting a tailored dielectric interlayer at the NW-Si interface, low-threshold single mode lasing can be achieved in vertical-cavity GaAs-AlGaAs core-shell NW lasers on silicon as measured at low temperature. By exploring the output characteristics along a detection direction parallel to the NW-axis, we measure very high spontaneous emission factors comparable to nanocavity lasers (β = 0.2) and achieve ultralow threshold pump energies ≤11 pJ/pulse. Analysis of the input-output characteristics of the NW lasers and the power dependence of the lasing emission line width demonstrate the potential for high pulsation rates ≥250 GHz. Such highly efficient nanolasers grown monolithically on silicon are highly promising for the realization of chip-level optical interconnects. PMID:26618638

  6. Optical biosensor based on silicon nanowire ridge waveguide

    Science.gov (United States)

    Gamal, Rania; Ismail, Yehia; Swillam, Mohamed A.

    2015-02-01

    Optical biosensors present themselves as an attractive solution for integration with the ever-trending lab-on-a-chip devices. This is due to their small size, CMOS compatibility, and invariance to electromagnetic interference. Despite their many benefits, typical optical biosensors rely on evanescent field detection, where only a small portion of the light interacts with the analyte. We propose to use a silicon nanowire ridge waveguide (SNRW) for optical biosensing. This structure is comprised of an array of silicon nanowires, with the envelope of a ridge, on an insulator substrate. The SNRW maximizes the overlap between the analyte and the incident light wave by introducing voids to the otherwise bulk structure, and strengthens the contribution of the material under test to the overall modal effective index will greatly augment the sensitivity. Additionally, the SNRW provides a fabrication convenience as it covers the entire substrate, ensuring that the etching process would not damage the substrate. FDTD simulations were conducted and showed that the percentage change in the effective index due to a 1% change in the surrounding environment was more than 170 times the amount of change perceived in an evanescent detection based bulk silicon ridge waveguide.

  7. Automatic Release of Silicon Nanowire Arrays with a High Integrity for Flexible Electronic Devices

    Science.gov (United States)

    Wu, Luo; Li, Shuxin; He, Weiwei; Teng, Dayong; Wang, Ke; Ye, Changhui

    2014-01-01

    Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etching process. The vertical Si nanowire array device, with both sides having high-quality Ohmic contact, can be transferred to arbitrary substrates, especially on a flexible substrate. The method developed here offers a facile method to realize flexible Si nanowire array functional devices. PMID:24487460

  8. Automatic release of silicon nanowire arrays with a high integrity for flexible electronic devices.

    Science.gov (United States)

    Wu, Luo; Li, Shuxin; He, Weiwei; Teng, Dayong; Wang, Ke; Ye, Changhui

    2014-01-01

    Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etching process. The vertical Si nanowire array device, with both sides having high-quality Ohmic contact, can be transferred to arbitrary substrates, especially on a flexible substrate. The method developed here offers a facile method to realize flexible Si nanowire array functional devices. PMID:24487460

  9. Electron transport in silicon nanowires having different cross-sections

    Directory of Open Access Journals (Sweden)

    Muscato Orazio

    2016-06-01

    Full Text Available Transport phenomena in silicon nanowires with different cross-section are investigated using an Extended Hydrodynamic model, coupled to the Schrödinger-Poisson system. The model has been formulated by closing the moment system derived from the Boltzmann equation on the basis of the maximum entropy principle of Extended Thermodynamics, obtaining explicit closure relations for the high-order fluxes and the production terms. Scattering of electrons with acoustic and non polar optical phonons have been taken into account. The bulk mobility is evaluated for square and equilateral triangle cross-sections of the wire.

  10. A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor

    OpenAIRE

    Jieun Lee; Jaeman Jang; Bongsik Choi; Jinsu Yoon; Jee-Yeon Kim; Yang-Kyu Choi; Dong Myong Kim; Dae Hwan Kim; Sung-Jin Choi

    2015-01-01

    This study demonstrates a hybrid biosensor comprised of a silicon nanowire (SiNW) integrated with an amplifier MOSFET to improve the current response of field-effect-transistor (FET)-based biosensors. The hybrid biosensor is fabricated using conventional CMOS technology, which has the potential advantage of high density and low noise performance. The biosensor shows a current response of 5.74 decades per pH for pH detection, which is 2.5 × 105 times larger than that of a single SiNW sensor. I...

  11. Creating New VLS Silicon Nanowire Contact Geometries by Controlling Catalyst Migration

    DEFF Research Database (Denmark)

    Alam, Sardar Bilal; Panciera, Federico; Hansen, Ole;

    2015-01-01

    The formation of self-assembled contacts between vapor-liquid-solid grown silicon nanowires and flat silicon surfaces was imaged in situ using electron microscopy. By measuring the structural evolution of the contact formation process, we demonstrate how different contact geometries are created by...... adjusting the balance between silicon deposition and Au migration. We show that electromigration provides an efficient way of controlling the contact. The results point to novel device geometries achieved by direct nanowire growth on devices....

  12. Top-Down Nanofabrication and Characterization of 20 nm Silicon Nanowires for Biosensing Applications

    OpenAIRE

    M. N, M. Nuzaihan; Hashim, U.; Md Arshad, M.K.; Ruslinda, A. Rahim; S.F.A. Rahman; Fathil, M. F. M.; Ismail, Mohd. H.

    2016-01-01

    A top-down nanofabrication approach is used to develop silicon nanowires from silicon-on-insulator (SOI) wafers and involves direct-write electron beam lithography (EBL), inductively coupled plasma-reactive ion etching (ICP-RIE) and a size reduction process. To achieve nanometer scale size, the crucial factors contributing to the EBL and size reduction processes are highlighted. The resulting silicon nanowires, which are 20 nm in width and 30 nm in height (with a triangular shape) and have a ...

  13. Smart integration of silicon nanowire arrays in all-silicon thermoelectric micro-nanogenerators

    Science.gov (United States)

    Fonseca, Luis; Santos, Jose-Domingo; Roncaglia, Alberto; Narducci, Dario; Calaza, Carlos; Salleras, Marc; Donmez, Inci; Tarancon, Albert; Morata, Alex; Gadea, Gerard; Belsito, Luca; Zulian, Laura

    2016-08-01

    Micro and nanotechnologies are called to play a key role in the fabrication of small and low cost sensors with excellent performance enabling new continuous monitoring scenarios and distributed intelligence paradigms (Internet of Things, Trillion Sensors). Harvesting devices providing energy autonomy to those large numbers of microsensors will be essential. In those scenarios where waste heat sources are present, thermoelectricity will be the obvious choice. However, miniaturization of state of the art thermoelectric modules is not easy with the current technologies used for their fabrication. Micro and nanotechnologies offer an interesting alternative considering that silicon in nanowire form is a material with a promising thermoelectric figure of merit. This paper presents two approaches for the integration of large numbers of silicon nanowires in a cost-effective and practical way using only micromachining and thin-film processes compatible with silicon technologies. Both approaches lead to automated physical and electrical integration of medium-high density stacked arrays of crystalline or polycrystalline silicon nanowires with arbitrary length (tens to hundreds microns) and diameters below 100 nm.

  14. Effective antireflection properties of porous silicon nanowires for photovoltaic applications

    KAUST Repository

    Najar, Adel

    2013-01-01

    Porous silicon nanowires (PSiNWs) have been prepared by metal-assisted chemical etching method on the n-Si substrate. The presence of nano-pores with pore size ranging between 10-50nm in SiNWs was confirmed by electron tomography (ET) in the transmission electron microscope (TEM). The PSiNWs give strong photoluminescence peak at red wavelength. Ultra-low reflectance of <5% span over wavelength 250 nm to 1050 nm has been measured. The finite-difference time-domain (FDTD) method has been employed to model the optical reflectance for both Si wafer and PSiNWs. Our calculation results are in agreement with the measured reflectance from nanowires length of 6 µm and 60% porosity. The low reflectance is attributed to the effective graded index of PSiNWs and enhancement of multiple optical scattering from the pores and nanowires. PSiNW structures with low surface reflectance can potentially serve as an antireflection layer for Si-based photovoltaic devices.

  15. AuPd CATALYTIC NANOPARTICLE SIZE EFFECT ON THE FORMATION OF AMORPHOUS SILICON NANOWIRES

    Institute of Scientific and Technical Information of China (English)

    LIU ZU-QIN; SUN LIAN-FENG; TANG DONG-SHENG; ZHOU WEI-YA; LI YU-BAO; Zou XIAO-PING

    2000-01-01

    Amorphous silicon (a-Si) nanowires have been prepared on SiO2/Si substrates by AuPd nanoparticles / silane reaction method. Field-emission scanning electron microscopy and transmission electron microscopy were used to characterize the samples. The typical a-Si nanowires we obtained are of a uniform diameter about 20 nm and length up to several micrometers. The growth mechanism of the nanowires seems to be the vapor-liquid-solid mechanism. The catalytic particle size effect on the formation of the nanowires and the cause of forming amorphous state Si nanowires are discussed.

  16. Controlling growth density and patterning of single crystalline silicon nanowires

    International Nuclear Information System (INIS)

    This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties.

  17. A silicon-nanowire memory driven by optical gradient force induced bistability

    International Nuclear Information System (INIS)

    In this paper, a bistable optical-driven silicon-nanowire memory is demonstrated, which employs ring resonator to generate optical gradient force over a doubly clamped silicon-nanowire. Two stable deformation positions of a doubly clamped silicon-nanowire represent two memory states (“0” and “1”) and can be set/reset by modulating the light intensity (<3 mW) based on the optical force induced bistability. The time response of the optical-driven memory is less than 250 ns. It has applications in the fields of all optical communication, quantum computing, and optomechanical circuits

  18. DRIE process optimization to fabricate vertical silicon nanowires using gold nanoparticles as masks

    Science.gov (United States)

    Bui, Thanh Tung; Phuc Tu, Hoan; Chien Dang, Mau

    2015-12-01

    Silicon nanowires have applications in various fields, e.g. vertical transistors, chemical or biological sensors, energy conversion, and storage devices. So far they have typically been obtained by bottom-up methods such as vapor-liquid-solid (VLS) synthesis, starting from metal nanoparticles. In this study, silicon nanowires are fabricated by dry reactive-ion etching using gold nanoparticles as a mask. Starting with the Bosch process, the cycle of SF6 plasma etching and C4F8 plasma deposition was optimized to control the quality of the resulting silicon nanowires.

  19. A silicon-nanowire memory driven by optical gradient force induced bistability

    Energy Technology Data Exchange (ETDEWEB)

    Dong, B. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), Singapore 117685 (Singapore); Cai, H., E-mail: caih@ime.a-star.edu.sg; Gu, Y. D.; Kwong, D. L. [Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), Singapore 117685 (Singapore); Chin, L. K.; Ng, G. I.; Ser, W. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Huang, J. G. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), Singapore 117685 (Singapore); School of Mechanical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Yang, Z. C. [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Liu, A. Q., E-mail: eaqliu@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)

    2015-12-28

    In this paper, a bistable optical-driven silicon-nanowire memory is demonstrated, which employs ring resonator to generate optical gradient force over a doubly clamped silicon-nanowire. Two stable deformation positions of a doubly clamped silicon-nanowire represent two memory states (“0” and “1”) and can be set/reset by modulating the light intensity (<3 mW) based on the optical force induced bistability. The time response of the optical-driven memory is less than 250 ns. It has applications in the fields of all optical communication, quantum computing, and optomechanical circuits.

  20. The mechanisms of platinum-catalyzed silicon nanowire growth

    International Nuclear Information System (INIS)

    Platinum (Pt) has been known as a catalyst material for vapor-liquid-solid (VLS) synthesis since the mid 1960s with the potential to grow electronic grade silicon nanowires (SiNWs). In contrast to gold-based growth, Pt-catalyzed SiNW synthesis has rarely been studied, most likely due to higher synthesis temperatures and the formation of multiple Pt silicide phases. Here we present the growth of SiNWs from a Pt catalyst deposited by a focused ion or electron beam, which opens new strategies for the assembly of Pt-catalyzed SiNW-based devices, as well as SiNW growth from Pt nanoparticles and thin films. We show that single-crystalline SiNWs exhibit either the well-known catalyst tip or a polycrystalline silicon tip so far not reported. The local Pt concentration was found to be one key parameter triggering the growth mode. The proposed growth model for both types of SiNWs is based on a solid-state silicide-mediated crystallization rather than VLS. The discussion of the growth modes is supported by a variation of several growth parameters and SiNW synthesis using the substrate materials silicon nitride, single-crystalline silicon, fused silica, and sapphire. (paper)

  1. The mechanisms of platinum-catalyzed silicon nanowire growth

    Science.gov (United States)

    Hibst, N.; Knittel, P.; Biskupek, J.; Kranz, C.; Mizaikoff, B.; Strehle, S.

    2016-02-01

    Platinum (Pt) has been known as a catalyst material for vapor-liquid-solid (VLS) synthesis since the mid 1960s with the potential to grow electronic grade silicon nanowires (SiNWs). In contrast to gold-based growth, Pt-catalyzed SiNW synthesis has rarely been studied, most likely due to higher synthesis temperatures and the formation of multiple Pt silicide phases. Here we present the growth of SiNWs from a Pt catalyst deposited by a focused ion or electron beam, which opens new strategies for the assembly of Pt-catalyzed SiNW-based devices, as well as SiNW growth from Pt nanoparticles and thin films. We show that single-crystalline SiNWs exhibit either the well-known catalyst tip or a polycrystalline silicon tip so far not reported. The local Pt concentration was found to be one key parameter triggering the growth mode. The proposed growth model for both types of SiNWs is based on a solid-state silicide-mediated crystallization rather than VLS. The discussion of the growth modes is supported by a variation of several growth parameters and SiNW synthesis using the substrate materials silicon nitride, single-crystalline silicon, fused silica, and sapphire.

  2. Incorporation and characterization of boron neutron capture therapy agents into mesoporous silicon and silicon nanowires

    International Nuclear Information System (INIS)

    The tunable pore size, biodegradability, and surface chemistry of mesoporous silicon (BioSilicon trademark) are important to a broad spectrum of uses for drug delivery. For the case of Boron Neutron Capture Therapy (BNCT), encapsulation of a given boron-containing drug molecule within a porous BioSilicon trademark microparticle provides a vehicle for a brachytherapy method that avoids the necessity of drug modification. In this work, the loading and characterization of three clinically approved BNCT drugs into mesoporous Si is demonstrated. Because of difficulties associated with light element detection, a method based on a Beer's Law analysis of selected FTIR vibrational bands has been developed to estimate boron-containing drug loading in these materials. As a complementary nanostructural platform, a cathodic deposition process for the surface enriched growth of selected drugs onto the surface of silicon nanowires is also described. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Incorporation and characterization of boron neutron capture therapy agents into mesoporous silicon and silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Ke; Coffer, Jeffery L. [Department of Chemistry, Texas Christian University, Fort Worth, TX 76129 (United States); Loni, Armando; Canham, Leigh T. [PSi Medica Ltd., Malvern, Worcestershire, WR14 3SZ (United Kingdom); Intrinsiq Materials Ltd., Malvern, Worcestershire, WR14 3SZ (United Kingdom)

    2009-06-15

    The tunable pore size, biodegradability, and surface chemistry of mesoporous silicon (BioSilicon trademark) are important to a broad spectrum of uses for drug delivery. For the case of Boron Neutron Capture Therapy (BNCT), encapsulation of a given boron-containing drug molecule within a porous BioSilicon trademark microparticle provides a vehicle for a brachytherapy method that avoids the necessity of drug modification. In this work, the loading and characterization of three clinically approved BNCT drugs into mesoporous Si is demonstrated. Because of difficulties associated with light element detection, a method based on a Beer's Law analysis of selected FTIR vibrational bands has been developed to estimate boron-containing drug loading in these materials. As a complementary nanostructural platform, a cathodic deposition process for the surface enriched growth of selected drugs onto the surface of silicon nanowires is also described. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Layered structure in core–shell silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Van Tuan, Pham [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam); Anh Tuan, Chu; Thanh Thuy, Tran; Binh Nam, Vu [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet Street, Hanoi 10000 (Viet Nam); Toan Thang, Pham [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam); Hong Duong, Pham, E-mail: duongphamhong@yahoo.com [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet Street, Hanoi 10000 (Viet Nam); Thanh Huy, Pham, E-mail: huy.phamthanh@hust.edu.vn [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam)

    2014-10-15

    Silicon nanowires (NWs) with core–shell structures were prepared using the Vapor–Liquid–Solid (VLS) method. The wires have lengths of several hundreds of nanometers and diameters in the range of 30–50 nm. Generally, these wires are too large to exhibit the quantum confinement effect of excitons in Si nanocrystals. However, the photoluminescence (PL) and Raman spectra are similar to those of nanocrystalline silicon embedded in a SiO{sub 2} matrix, in which the recombination of quantum-confined excitons plays an important role. This effect occurs only when the average size of the silicon nanocrystals is smaller than 5 nm. To understand this discrepancy, TEM images of nanowires were obtained and analyzed. The results revealed that the cores of wires have a layered Si/SiO{sub 2} structure, in which the thickness of each layer is much smaller than its diameter. The temperature dependence of the PL intensity was recorded from 11 to 300 K; the result is in good agreement with a model that takes into account the energy splitting between the excitonic singlet and triplet levels. - Highlights: • The cores of the Si NWs have a layered Si/SiO{sub 2} structure. • The Si NWs were formed due to the phase separation of Si and SiO{sub 2} and the partial oxidization by residual oxygen. • Two processes, the reaction of Si and oxygen atoms and the combination between Si atoms, occur simultaneously. • The formation of the layered structures is associated with the self-limiting oxidation phenomenon in Si nanostructures.

  5. Layered structure in core–shell silicon nanowires

    International Nuclear Information System (INIS)

    Silicon nanowires (NWs) with core–shell structures were prepared using the Vapor–Liquid–Solid (VLS) method. The wires have lengths of several hundreds of nanometers and diameters in the range of 30–50 nm. Generally, these wires are too large to exhibit the quantum confinement effect of excitons in Si nanocrystals. However, the photoluminescence (PL) and Raman spectra are similar to those of nanocrystalline silicon embedded in a SiO2 matrix, in which the recombination of quantum-confined excitons plays an important role. This effect occurs only when the average size of the silicon nanocrystals is smaller than 5 nm. To understand this discrepancy, TEM images of nanowires were obtained and analyzed. The results revealed that the cores of wires have a layered Si/SiO2 structure, in which the thickness of each layer is much smaller than its diameter. The temperature dependence of the PL intensity was recorded from 11 to 300 K; the result is in good agreement with a model that takes into account the energy splitting between the excitonic singlet and triplet levels. - Highlights: • The cores of the Si NWs have a layered Si/SiO2 structure. • The Si NWs were formed due to the phase separation of Si and SiO2 and the partial oxidization by residual oxygen. • Two processes, the reaction of Si and oxygen atoms and the combination between Si atoms, occur simultaneously. • The formation of the layered structures is associated with the self-limiting oxidation phenomenon in Si nanostructures

  6. Fabrication of horizontally grown silicon nanowires using a thin aluminum film as a catalyst

    International Nuclear Information System (INIS)

    We present a new method for the fabrication of horizontal silicon nanowires for application in nanoelectronic devices. A web of horizontally connected silicon nanowires is grown on a silicon substrate using a thin aluminum film as a catalyst. A thin layer of oxide is thermally grown on a silicon substrate. The oxide layer is then selectively etched using photolithography. A thin layer of aluminum is thermally evaporated on the substrate with the patterned oxide layer. When the sample is annealed above the eutectic temperature, we show that the silicon gets deposited along the grain boundaries of aluminum in the form of thin nanowires. We show that this phenomenon is due to the high solubility of silicon in aluminum at high temperatures. The surface morphology was analyzed using Scanning Electron Microscopy (SEM). The compositional analysis was done using Energy Dispersive X-ray spectroscopy (EDX).

  7. Directed deposition of silicon nanowires using neopentasilane as precursor and gold as catalyst

    Directory of Open Access Journals (Sweden)

    Britta Kämpken

    2012-07-01

    Full Text Available In this work the applicability of neopentasilane (Si(SiH34 as a precursor for the formation of silicon nanowires by using gold nanoparticles as a catalyst has been explored. The growth proceeds via the formation of liquid gold/silicon alloy droplets, which excrete the silicon nanowires upon continued decomposition of the precursor. This mechanism determines the diameter of the Si nanowires. Different sources for the gold nanoparticles have been tested: the spontaneous dewetting of gold films, thermally annealed gold films, deposition of preformed gold nanoparticles, and the use of “liquid bright gold”, a material historically used for the gilding of porcelain and glass. The latter does not only form gold nanoparticles when deposited as a thin film and thermally annealed, but can also be patterned by using UV irradiation, providing access to laterally structured layers of silicon nanowires.

  8. Synthesize of barium ferrite nanowire array by self-fabricated porous silicon template

    Science.gov (United States)

    Zheng, Hui; Han, Mangui; Deng, Jiangxia; Zheng, Liang; Wu, Jun; Deng, Longjiang; Qin, Huibin

    2014-08-01

    In this work, we synthesize barium ferrite (BaFe12O19) nanowire array in porous silicon template. The porous silicon templates are prepared via gold-assisted chemical etching method. The gold (Au) nanoparticles with mean diameter of 30 nm and distance of 100 nm were ordered on the surface of Si substrate through the Polystyrene (510000)-block-poly (2-vinylpyridine) (31000) (PS510000-b-P2VP31000) diblock copolymer. Porous silicon templates with mean diameter of 500 nm and distance between the pores of 500 nm were fabricated by two etching steps. BaFe12O19 nanowires with mean diameter of 200 nm were synthesized into a porous silicon template by a sol-gel method. Magnetic hysteresis loops show an isotropic feature of the BaFe12O19 nanowires array. The coercivity (Hc) and squareness ratio (Mr/Ms) of nanowire arrays are 2560 Oe and 0.6, respectively.

  9. Conductive-probe atomic force microscopy characterization of silicon nanowire

    Directory of Open Access Journals (Sweden)

    Yu Linwei

    2011-01-01

    Full Text Available Abstract The electrical conduction properties of lateral and vertical silicon nanowires (SiNWs were investigated using a conductive-probe atomic force microscopy (AFM. Horizontal SiNWs, which were synthesized by the in-plane solid-liquid-solid technique, are randomly deployed into an undoped hydrogenated amorphous silicon layer. Local current mapping shows that the wires have internal microstructures. The local current-voltage measurements on these horizontal wires reveal a power law behavior indicating several transport regimes based on space-charge limited conduction which can be assisted by traps in the high-bias regime (> 1 V. Vertical phosphorus-doped SiNWs were grown by chemical vapor deposition using a gold catalyst-driving vapor-liquid-solid process on higly n-type silicon substrates. The effect of phosphorus doping on the local contact resistance between the AFM tip and the SiNW was put in evidence, and the SiNWs resistivity was estimated.

  10. Nanoscale contact engineering for Silicon/Silicide nanowire devices

    Science.gov (United States)

    Lin, Yung-Chen

    Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at nanoscale have indicated possible deviations from the bulk and the thin film system. Here we studied growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction. We have grown single crystal PtSi nanowires and PtSi/Si/PtSi nanowire heterostructures through solid state reaction. TEM studies show that the heterostructures have atomically sharp interfaces free of defects. Electrical measurement of PtSi nanowires shows a low resistivity of ˜28.6 μΩ·cm and a high breakdown current density beyond 108 A/cm2. Furthermore, using single-crystal PtSi/Si/PtSi nanowire heterostructures with atomically clean interfaces, we have fabricated p-channel enhancement mode transistors with the best reported performance for intrinsic silicon nanowires to date. In our results, silicide can provide a clean and no Fermi level pinning interface and then silicide can form Ohmic-contact behavior by replacing the source/drain metal with PtSi. It has been proven by our experiment by contacting PtSi with intrinsic Si nanowires (no extrinsic doping) to achieve high performance p-channel device. By utilizing the same approach, single crystal MnSi nanowires and MnSi/Si/MnSi nanowire heterojunction with atomically sharp interfaces can also been grown. Electrical transport studies on Mn

  11. Polarization Insensitive One-to-Six WDM Multicasting in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Peucheret, Christophe;

    2012-01-01

    We present polarization insensitive one-to-six WDM multicasting based on nondegenerate four-wave mixing in a silicon nanowire with angled-pump scheme. Bit-error rate measurements are performed and error-free operation is achieved.......We present polarization insensitive one-to-six WDM multicasting based on nondegenerate four-wave mixing in a silicon nanowire with angled-pump scheme. Bit-error rate measurements are performed and error-free operation is achieved....

  12. Probing ultrafast carrier dynamics and nonlinear absorption and refraction in core-shell silicon nanowires

    OpenAIRE

    Kumar, Sunil; Khorasaninejad, M.; Adachi, MM; Karim, KS; Saini, SS; Sood, AK

    2012-01-01

    We investigate the relaxation dynamics of photogenerated carriers in silicon nanowires consisting of a crystalline core and a surrounding amorphous shell, using femtosecond time-resolved differential reflectivity and transmission spectroscopy at 3.15 eV and 1.57 eV photon energies. The complex behaviour of the differential transmission and reflectivity transients is the mixed contributions from the crystalline core and the amorphous silicon on the nanowire surface and the substrate where comp...

  13. Platinum nanoparticle decorated silicon nanowires for efficient solar energy conversion.

    Science.gov (United States)

    Peng, Kui-Qing; Wang, Xin; Wu, Xiao-Ling; Lee, Shuit-Tong

    2009-11-01

    High-density aligned n-type silicon nanowire (SiNW) arrays decorated with discrete 5-10 nm platinum nanoparticles (PtNPs) have been fabricated by aqueous electroless Si etching followed by an electroless platinum deposition process. Coating of PtNPs on SiNW sidewalls yielded a substantial enhancement in photoconversion efficiency and an apparent energy conversion efficiency of up to 8.14% for the PtNP-decorated SiNW-based photoelectrochemical solar cell using a liquid electrolyte containing Br(-)/Br(2) redox couple. The results demonstrate PtNP-decorated SiNWs to be a promising hybrid system for solar energy conversion. PMID:19807069

  14. Silicon nanowires for high-sensitivity glucose detection

    Science.gov (United States)

    Chen, Weiwei; Yao, Hui; Tzang, Chi Hung; Zhu, Junjie; Yang, Mengsu; Lee, Shuit-Tong

    2006-05-01

    Silicon nanowires (SiNWs) were investigated as supporting matrices for enzyme immobilization to construct glucose biosensors. Glucose oxidase was adsorbed onto SiNWs after different treatments, either as grown, HF etched, or carboxylic acid (COOH) functionalized. The amperometric biosensor with COOH-functionalized SiNWs performed the best with a detection limit of 0.01mM glucose (signal-to-noise ratio=3). For real-time detection of glucose, SiNW biosensor showed a linear response in the range of 0.1-15mM. This work demonstrates the utility of SiNWs as a biosensor component and provides a general method to modify the surface of semiconducting nanomaterials for potential biomedical applications.

  15. Growth mechanism and quantum confinement effect of silicon nanowires

    Institute of Scientific and Technical Information of China (English)

    冯孙齐; 俞大鹏; 张洪洲; 白志刚; 丁彧; 杭青岭; 邹英华; 王晶晶

    1999-01-01

    The methods for synthesizing one-dimensional Si nanowires with controlled diameter are introduced. The mechanism for the growth of Si nanowires and the growth model for different morphologies of Si nanowires are described, and the quantum confinement effect of the Si nanowires is presented.

  16. Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

    KAUST Repository

    Ruffo, Riccardo

    2009-07-02

    The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured by using impedance spectroscopy in equilibrium conditions at different lithium compositions and during several cycles of charge and discharge in a half cell vs. metallic lithium. The impedance analysis shows the contribution of both surface resistance and solid state diffusion through the bulk of the nanowires. The surface process is dominated by a solid electrolyte layer (SEI) consisting of an inner, inorganic insoluble part and several organic compounds at the outer interface, as seen by XPS analysis. The surface resistivity, which seems to be correlated with the Coulombic efficiency of the electrode, grows at very high lithium contents due to an increase in the inorganic SEI thickness. We estimate the diffusion coefficient of about 2 × 10 -10 cm 2/s for lithium diffusion in silicon. A large increase in the electrode impedance was observed at very low lithium compositions, probably due to a different mechanism for lithium diffusion inside the wires. Restricting the discharge voltage to 0.7 V prevents this large impedance and improves the electrode lifetime. Cells cycled between 0.07 and 0.70 V vs. metallic lithium at a current density of 0.84 A/g (C/5) showed good Coulombic efficiency (about 99%) and maintained a capacity of about 2000 mAh/g after 80 cycles. © 2009 American Chemical Society.

  17. Effect of Fe metal on the growth of silicon oxide nanowires

    Institute of Scientific and Technical Information of China (English)

    Wei-long Liu; Shu-huei Hsieh; Ching-He Chen; Wen-jauh Chen

    2009-01-01

    Silicon oxide (SiOx) nanowires are generally grown on Si substrate under the catalysis of Au in N2 atmosphere at elevated temperatures. Because the price of Au metal is quite high, Fe metal is then used to replace a part of Au for catalyzing the growth of SiOx nanowires. The results show that the Fe film can be used as the diffusion barrier of Au. SiOx nanowires are grown on Au/Fe/Si substrate at 1030℃. Under the catalysis of Fe/Au, the efficiency for the growth of SiOx nanowires is promoted.

  18. Filter-free image sensor pixels comprising silicon nanowires with selective color absorption.

    Science.gov (United States)

    Park, Hyunsung; Dan, Yaping; Seo, Kwanyong; Yu, Young J; Duane, Peter K; Wober, Munib; Crozier, Kenneth B

    2014-01-01

    The organic dye filters of conventional color image sensors achieve the red/green/blue response needed for color imaging, but have disadvantages related to durability, low absorption coefficient, and fabrication complexity. Here, we report a new paradigm for color imaging based on all-silicon nanowire devices and no filters. We fabricate pixels consisting of vertical silicon nanowires with integrated photodetectors, demonstrate that their spectral sensitivities are governed by nanowire radius, and perform color imaging. Our approach is conceptually different from filter-based methods, as absorbed light is converted to photocurrent, ultimately presenting the opportunity for very high photon efficiency. PMID:24588103

  19. Optical characteristics of silicon nanowires grown from tin catalyst layers on silicon coated glass

    KAUST Repository

    Ball, Jeremy

    2012-08-20

    The optical characteristics of silicon nanowires grown on Si layers on glass have been modeled using the FDTD (Finite Difference Time Domain) technique and compared with experimental results. The wires were grown by the VLS (vapour-liquid-solid) method using Sn catalyst layers and exhibit a conical shape. The resulting measured and modeled absorption, reflectance and transmittance spectra have been investigated as a function of the thickness of the underlying Si layer and the initial catalyst layer, the latter having a strong influence on wire density. High levels of absorption (>90% in the visible wavelength range) and good agreement between the modeling and experiment have been observed when the nanowires have a relatively high density of ∼4 wires/μ m2. The experimental and modeled results diverge for samples with a lower density of wire growth. The results are discussed along with some implications for solar cell fabrication. © 2012 Optical Society of America.

  20. Chemically Etched Silicon Nanowires as Anodes for Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    West, Hannah Elise [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    This study focused on silicon as a high capacity replacement anode for Lithium-ion batteries. The challenge of silicon is that it expands ~270% upon lithium insertion which causes particles of silicon to fracture, causing the capacity to fade rapidly. To account for this expansion chemically etched silicon nanowires from the University of Maine were studied as anodes. They were built into electrochemical half-cells and cycled continuously to measure the capacity and capacity fade.

  1. Silicon Nanowires for All-Optical Signal Processing in Optical Communication

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua;

    2012-01-01

    such as four-wave mixing (FWM) which is an imperative process for optical signal processing. Since the current mature silicon fabrication technology enables a precise dimension control on nanowires, dispersion engineering can be performed by tailoring nanowire dimensions to realize an efficient nonlinear...... process. In the last four years, we investigated and demonstrated different ultra-fast all-optical nonlinear signal processing applications in silicon nanowires for optical time domain multiplexing (OTDM) systems, including wavelength conversion, signal regeneration, ultra-fast waveform sampling......, demultiplexing, and multicasting, which shows great potentials in the future optical communication systems. Although the strong light confinement in nanowires allows efficient nonlinear optical signal processing, it also leads to coupling difficulty between on-chip sub-micron nanowires and micro-size fibers due...

  2. Study of optical absorbance in porous silicon nanowires for photovoltaic applications

    KAUST Repository

    Charrier, Joël

    2013-10-01

    Porous silicon nanowires (PSiNWs) layers fabrication was reported. Reflectance spectra were measured as a function of the nanowire length and were inferior to 0.1% and a strong photoluminescence (PL) signal was measured from samples. Models based on cone shape of nanowires located in circular and rectangular bases were used to calculate the reflectance using the transfer matrix formalism (TMF) of PSiNWs layer. The modeling of the reflectance permits to explain this value by taking account into the shape of the nanowires and its porosity. Optical absorbance and transmission were also theoretically studied. The absorbance was superior to that obtained with silicon nanowires and the ultimate efficiency was about equal to 25% for normal incidence angle. These results could be applied to the potential application in low-cost and high efficiency PSiNWs based solar cells. © 2013 Elsevier B.V. All rights reserved.

  3. Comparison of ordered and disordered silicon nanowire arrays: experimental evidence of photonic crystal modes.

    Science.gov (United States)

    Dhindsa, Navneet; Saini, Simarjeet S

    2016-05-01

    We experimentally compared the reflectance between ordered and disordered silicon nanowires to observe the evidence of photonic crystal modes. For similar diameters, the resonance peaks for the ordered nanowires at a spacing of 400 nm was at a shorter wavelength than the disordered nanowires, consistent to the excitation of photonic crystal modes. Furthermore, the resonant wavelength didn't shift while changing the density of the disordered nanowires, whereas there was a significant shift observed in the ordered ones. At an ordered spacing of 800 nm, the resonance wavelength approached that of the disordered structures, indicating that the ordered structures were starting to behave like individual waveguides. To our knowledge, this is the first direct experimental observation of photonic crystal modes in vertical periodic silicon nanowire arrays. PMID:27128070

  4. Phonon processes in vertically aligned silicon nanowire arrays produced by low-cost all-solution galvanic displacement method

    Science.gov (United States)

    Banerjee, Debika; Trudeau, Charles; Gerlein, Luis Felipe; Cloutier, Sylvain G.

    2016-03-01

    The nanoscale engineering of silicon can significantly change its bulk optoelectronic properties to make it more favorable for device integration. Phonon process engineering is one way to enhance inter-band transitions in silicon's indirect band structure alignment. This paper demonstrates phonon localization at the tip of silicon nanowires fabricated by galvanic displacement using wet electroless chemical etching of a bulk silicon wafer. High-resolution Raman micro-spectroscopy reveals that such arrayed structures of silicon nanowires display phonon localization behaviors, which could help their integration into the future generations of nano-engineered silicon nanowire-based devices such as photodetectors and solar cells.

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

    Science.gov (United States)

    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.

  6. Top-down fabrication of silicon nanowire devices for thermoelectric applications: properties and perspectives

    Science.gov (United States)

    Pennelli, Giovanni

    2015-05-01

    In this paper, the most recent achievements in the field of device fabrication, based on nanostructured silicon, will be reviewed. Top-down techniques for silicon nanowire production based on lithography, oxidation and highly anisotropic etching (wet, plasma and metal assisted) will be discussed, illustrating both advantages and drawbacks. In particular, fabrication processes for a massive production of silicon nanowires, organized and interconnected in devices with macroscopic dimensions, will be shown and discussed. These macroscopic devices offer the possibility of exploiting the nanoscale thermoelectric properties of silicon in practical applications. In particular, the reduced thermal conductivity of silicon nanowires, with respect to bulk silicon, makes possible to obtain high efficiencies in the direct conversion of heat into electrical power, with intriguing applications in the field of green energy harvesting. The main experiments elucidating the electrical and thermal properties of silicon nanowire devices will be shown and discussed, and compared with the recent theoretical works developed on the subject. Contribution to the Topical Issue "Silicon and Silicon-related Materials for Thermoelectricity", edited by Dario Narducci.

  7. Performance Analysis of Silicon and Germanium Nanowire Transistor using Crystal Orientation and Oxide Thickness

    Directory of Open Access Journals (Sweden)

    P.Theres Mary

    2014-09-01

    Full Text Available Nanowire Transistors have attracted attention due to the probable high performance and excellent controllability of device current. In this paper, we investigate the performance analysis of nanowire transistors made of silicon and germanium materials. The nanowire transistor has a 3D distribution of electron density and electrostatic potential, therefore self-consistent 3D simulations are used. Nanowire (tool is 3D Poisson self-consistent simulator which can study the 3D transport in nanowire transistor considering phonon scattering based on the effective-mass approximation. The output characteristics of the nanowire transistors are studied in detail for both Si and Ge materials for different transport orientation (i.e., 100,110,111 and varying the oxide thickness.

  8. Bimetal Ga-Sn catalyzed growth for the novel morphologies of silicon oxide nanowires

    International Nuclear Information System (INIS)

    The large size, low melting point bimetal Ga-Sn can be used as an effective catalyst for the large-scale growth of highly aligned, closely packed silicon oxide nanowires bunches. The experimental results show that the silicon oxide nanowires tend to grow bunch by bunch. For each bunch, numerous nanowires simultaneously nucleate, grow at nearly the same rate and direction, and simultaneously stop growing. The prickly spheres, whisk-like, echinus-like, hedgehog-like, and dandelions-like silicon oxide nanowires were formed under different atomic ratio of Ga and Sn in the alloy ball. A growth model was proposed. The experimental results further expand the growth mechanism of the quasi-one-dimensional nanostructures to a broader range

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

    Science.gov (United States)

    Pan, Hui

    2014-01-01

    Design of novel materials for efficient solar energy conversion is critical to the development of green energy technology. In this work, we present a first-principles study on the design of nanostructures for solar energy harvesting on the basis of the density functional theory. We show that the indirect band structure of bulk silicon nitride is transferred to direct bandgap in nanowire. We find that intermediate bands can be created by doping, leading to enhancement of sunlight absorption. We further show that codoping not only reduces the bandgap and introduces intermediate bands but also enhances the solubility of dopants in silicon nitride nanowires due to reduced formation energy of substitution. Importantly, the codoped nanowire is ferromagnetic, leading to the improvement of carrier mobility. The silicon nitride nanowires with direct bandgap, intermediate bands, and ferromagnetism may be applicable to solar energy harvesting. PMID:25294975

  10. Prelithiated Silicon Nanowires as an Anode for Lithium Ion Batteries

    KAUST Repository

    Liu, Nian

    2011-08-23

    Silicon is one of the most promising anode materials for the next-generation high-energy lithium ion battery (LIB), while sulfur and some other lithium-free materials have recently shown high promise as cathode materials. To make a full battery out of them, either the cathode or the anode needs to be prelithiated. Here, we present a method for prelithiating a silicon nanowire (SiNW) anode by a facile self-discharge mechanism. Through a time dependence study, we found that 20 min of prelithiation loads ∼50% of the full capacity into the SiNWs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies show that the nanostructure of SiNWs is maintained after prelithiation. We constructed a full battery using our prelithiated SiNW anode with a sulfur cathode. Our work provides a protocol for pairing lithium-free electrodes to make the next-generation high-energy LIB. © 2011 American Chemical Society.

  11. Quantitative measurements of C-reactive protein using silicon nanowire arrays

    Directory of Open Access Journals (Sweden)

    Min-Ho Lee

    2008-03-01

    Full Text Available Min-Ho Lee, Kuk-Nyung Lee, Suk-Won Jung, Won-Hyo Kim, Kyu-Sik Shin, Woo-Kyeong SeongKorea Electronics Technology Institute, Gyeonggi, KoreaAbstract: A silicon nanowire-based sensor for biological application showed highly desirable electrical responses to either pH changes or receptor-ligand interactions such as protein disease markers, viruses, and DNA hybridization. Furthermore, because the silicon nanowire can display results in real-time, it may possess superior characteristics for biosensing than those demonstrated in previously studied methods. However, despite its promising potential and advantages, certain process-related limitations of the device, due to its size and material characteristics, need to be addressed. In this article, we suggest possible solutions. We fabricated silicon nanowire using a top-down and low cost micromachining method, and evaluate the sensing of molecules after transfer and surface modifications. Our newly designed method can be used to attach highly ordered nanowires to various substrates, to form a nanowire array device, which needs to follow a series of repetitive steps in conventional fabrication technology based on a vapor-liquid-solid (VLS method. For evaluation, we demonstrated that our newly fabricated silicon nanowire arrays could detect pH changes as well as streptavidin-biotin binding events. As well as the initial proof-of-principle studies, C-reactive protein binding was measured: electrical signals were changed in a linear fashion with the concentration (1 fM to 1 nM in PBS containing 1.37 mM of salts. Finally, to address the effects of Debye length, silicon nanowires coupled with antigen proteins underwent electrical signal changes as the salt concentration changed.Keywords: silicon nanowire array, C-reactive protein, vapor-liquid-solid method

  12. Fabrication of β-Silicon Carbide Nanowires from Carbon Powder and Silicon Wafer

    Directory of Open Access Journals (Sweden)

    Majid S. Al-Ruqeishi

    2016-06-01

    Full Text Available β-SiCNWs were synthesized by simple carbo-thermal process using silicon wafer and carbon powder only. The obtained β-SiCNWs were short and thick with random distribution over Si wafer surface when rapid heating rate is applied. While β-SiCNWs fabricated under low heating rate are 57.0±3.0 nm in average diameter and few millimeters in length. An ambient Ar gas flow rates were found to be critical in the growth yield of resultant β-SiC nanowires. XRD diffraction patterns and FTIR spectrum reveals the composition structure of theses wires.

  13. Synthesis of porous silicon nano-wires and the emission of red luminescence

    International Nuclear Information System (INIS)

    This very paper is focusing on the characterization of porous silicon nano-wires prepared via a two-step route, the electroless chemical etching and the following post-treatment of HF/HNO3 solution. Hence, scanning electron microscopy, transmission electron microscopy and confocal fluorescence microscopy are employed for this purpose. From the results of experiments, one can find that the as-prepared silicon nano-wire is of smooth surface and that no visible photo-luminescence emission could be seen. However, the porous structure can be found in the silicon nano-wire treated with HF/HNO3 solution, and the clear photo-luminescence emission of 630 nm can be recorded with a confocal fluorescence microscope. The transmission electron microscopy test tells that the porous silicon nano-wire is made up of a porous crystalline silicon nano-core and a rough coating of silicon oxide. Besides, based on the post-HF- and -H2O2- treatments, the emission mechanism of the red luminescence has been discussed and could be attributed to the quantum confinement/luminescence center model which could be simply concluded as that the electron–hole pairs are mainly excited inside the porous silicon nano-core and then tunneling out and recombining at the silicon oxide coating.

  14. Synthesis of porous silicon nano-wires and the emission of red luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Congli, Sun [School of Materials Science and Engineering, Sichuan University (China); Hao, Hu [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, Sichuan (China); Huanhuan, Feng; Jingjing, Xu; Yu, Chen; Yong, Jin; Zhifeng, Jiao [School of Materials Science and Engineering, Sichuan University (China); Xiaosong, Sun, E-mail: sunxs@scu.edu.cn [School of Materials Science and Engineering, Sichuan University (China)

    2013-10-01

    This very paper is focusing on the characterization of porous silicon nano-wires prepared via a two-step route, the electroless chemical etching and the following post-treatment of HF/HNO{sub 3} solution. Hence, scanning electron microscopy, transmission electron microscopy and confocal fluorescence microscopy are employed for this purpose. From the results of experiments, one can find that the as-prepared silicon nano-wire is of smooth surface and that no visible photo-luminescence emission could be seen. However, the porous structure can be found in the silicon nano-wire treated with HF/HNO{sub 3} solution, and the clear photo-luminescence emission of 630 nm can be recorded with a confocal fluorescence microscope. The transmission electron microscopy test tells that the porous silicon nano-wire is made up of a porous crystalline silicon nano-core and a rough coating of silicon oxide. Besides, based on the post-HF- and -H{sub 2}O{sub 2}- treatments, the emission mechanism of the red luminescence has been discussed and could be attributed to the quantum confinement/luminescence center model which could be simply concluded as that the electron–hole pairs are mainly excited inside the porous silicon nano-core and then tunneling out and recombining at the silicon oxide coating.

  15. Surface trap mediated electronic transport in biofunctionalized silicon nanowires

    Science.gov (United States)

    Puppo, F.; Traversa, F. L.; Di Ventra, M.; De Micheli, G.; Carrara, S.

    2016-08-01

    Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface electronic transport in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I–V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I–V characteristics in other nanostructured devices, for different than antibody-based sensing as well as electronic applications.

  16. Stress redistribution in individual ultrathin strained silicon nanowires: a high-resolution polarized Raman study

    International Nuclear Information System (INIS)

    Strain nano-engineering provides valuable opportunities to create high-performance nanodevices by a precise tailoring of semiconductor band structure. Achieving these enhanced capabilities has sparked a surge of interest in controlling strain on the nanoscale. In this work, the stress behavior in ultrathin strained silicon nanowires directly on oxide is elucidated using background-free, high-resolution polarized Raman spectroscopy. We established a theoretical framework to quantify the stress from Raman shifts taking into account the anisotropy associated with the nanowire quasi-one-dimensional morphology. The investigated nanowires have lateral dimensions of 30, 50 and 80 nm and a length of 1 μm top-down fabricated by patterning and etching 15 nm thick biaxially tensile strained silicon nanomembranes generated using heteroepitaxy and ultrathin layer transfer. The concern over the contribution of Raman scattering at the nanowire 〈110〉 oriented sidewalls is circumvented by precisely selecting the incident polarization relative to the sidewalls of the nanowire, thus enabling an accurate and rigorous analysis of stress profiles in individual nanowires. Unlike suspended nanowires, which become uniaxially strained as a result of free surface-induced relaxation, we demonstrated that stress profiles in single nanowires are rather complex and non-uniform along different directions due to the oxide–nanowire interface. As a general trend, higher stresses are observed at the center of the nanowire and found to decrease linearly as a function of the nanowire width. Using multi-wavelength high-resolution Raman spectroscopy, we also extracted the stress profiles at different depths in the nanowire. The residual stress in the top ∼10 nm of the nanowire was found to be nearly uniaxial and increase from the edge toward the center, which remains highly strained. In contrast, the average stress profiles measured over the whole nanowire thickness exhibit different behavior

  17. Long Wavelength Plasmonic Absorption Enhancement in Silicon Using Optical Lithography Compatible Core-Shell-Type Nanowires

    Directory of Open Access Journals (Sweden)

    Mohammed Shahriar Sabuktagin

    2014-01-01

    Full Text Available Plasmonic properties of rectangular core-shell type nanowires embedded in thin film silicon solar cell structure were characterized using FDTD simulations. Plasmon resonance of these nanowires showed tunability from  nm. However this absorption was significantly smaller than the Ohmic loss in the silver shell due to very low near-bandgap absorption properties of silicon. Prospect of improving enhanced absorption in silicon to Ohmic loss ratio by utilizing dual capability of these nanowires in boosting impurity photovoltaic effect and efficient extraction of the photogenerated carriers was discussed. Our results indicate that high volume fabrication capacity of optical lithography techniques can be utilized for plasmonic absorption enhancement in thin film silicon solar cells over the entire long wavelength range of solar radiation.

  18. Silicon nanowires prepared by thermal evaporation and their photoluminescence properties measured at low temperatures

    International Nuclear Information System (INIS)

    In the present work, silicon nanowires were prepared by a thermal evaporation method. The evaporating source was a mixture of silicon and carbon nanopowders. Surface morphology, structural characteristics and emission properties of the silicon nanowires were investigated by several techniques. The results showed that the obtained products have the shape of nanowires with diameters ranging from 30 to 120 nm and lengths from 300 to 400 nm. The x-ray diffraction (XRD) patterns confirmed the presence of crystalline silicon. Transmission electron microscope (TEM) images revealed the core-shell structure of the wires. In the photoluminescence (PL) spectra recorded at room temperature, only a broad emission band peaking at about 650 nm was observed. In addition to the red emission, two other bands centered at around 455 nm and 510 nm appeared when measured at low temperatures. The origin and emission mechanism of these bands are discussed

  19. Electrowetting properties of atomic layer deposited Al2O3 decorated silicon nanowires

    International Nuclear Information System (INIS)

    This paper reports the electrowetting properties of liquid droplet on superhydrophobic silicon nanowires with Atomic layer deposited (ALD) Al2O3 as dielectric layer. Silicon wafer were etched by metal assisted wet chemical etching with silver as catalyst. ALD Al2O3 films of 10nm thickness were conformally deposited over silicon nanowires. Al2O3 dielectric film coated silicon nanowires was chemically modified with Trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane to make it superhydrophobic(SHP). The contact angle was measured and all the samples exhibited superhydrophobic nature with maximum contact angles of 163° and a minimum contact angle hysteresis of 6°. Electrowetting induced a maximum reversible decrease of the contact angle of 20°at 150V in air

  20. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution.

    Science.gov (United States)

    Bao, Xiao-Qing; Fatima Cerqueira, M; Alpuim, Pedro; Liu, Lifeng

    2015-07-01

    We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction. PMID:26050844

  1. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution

    OpenAIRE

    Bao, Xiao-Qing; Cerqueira, M. F.; Alpuim, P.; Liu, Lifeng

    2015-01-01

    We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction.

  2. Molecular dynamics simulation overcoming the finite size effects of thermal conductivity of bulk silicon and silicon nanowires

    Science.gov (United States)

    Hou, Chaofeng; Xu, Ji; Ge, Wei; Li, Jinghai

    2016-05-01

    Nonequilibrium molecular dynamics simulation has been a powerful tool for studying the thermophysical properties of bulk silicon and silicon nanowires. Nevertheless, usually limited by the capacity and capability of computational resources, the traditional longitudinal and transverse simulation sizes are evidently restricted in a narrow range much less than the experimental scales, which seriously hinders the exploration of the thermal properties. In this research, based on a powerful and efficient molecular dynamics (MD) simulation method, the computation of thermal conductivity beyond the known Casimir size limits is realized. The longitudinal dimensions of the simulations significantly exceed the micrometer scale. More importantly, the lateral characteristic sizes are much larger than 10 nanometers, explicitly comparable with the silicon nanowires fabricated and measured experimentally, whereas the traditional simulation size is several nanometers. The powerful virtual experimental measurement provided in our simulations achieves the direct prediction of the thermal conductivity of bulk silicon and real-scale silicon nanowires, and delineates the complete longitudinal size dependence of their thermal conductivities, especially at the elusive mesoscopic scale. Furthermore, the presented measurement paves an exciting and promising way to explore in depth the thermophysical properties of other bulk covalent solids and their low-dimensional structures, such as nanowires and nanosheets.

  3. Functionalization of silicon nanowire surfaces with metal-organic frameworks

    KAUST Repository

    Liu, Nian

    2011-12-28

    Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  4. Effects of lithium insertion on thermal conductivity of silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wen [Department of Physics, Centre for Advanced 2D Material and Centre for Computational Science and Engineering, National University of Singapore, Singapore, Singapore 117546 (Singapore); Institute of High Performance Computing, A*STAR, Singapore, Singapore 138632 (Singapore); Zhang, Gang, E-mail: zhangg@ihpc.a-star.edu.sg [Institute of High Performance Computing, A*STAR, Singapore, Singapore 138632 (Singapore); Li, Baowen [Department of Physics, Centre for Advanced 2D Material and Centre for Computational Science and Engineering, National University of Singapore, Singapore, Singapore 117546 (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Kent Ridge, Singapore 119620 (Singapore); Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, 200092 Shanghai (China)

    2015-04-27

    Recently, silicon nanowires (SiNWs) have been applied as high-performance Li battery anodes, since they can overcome the pulverization and mechanical fracture during lithiation. Although thermal stability is one of the most important parameters that determine safety of Li batteries, thermal conductivity of SiNWs with Li insertion remains unclear. In this letter, using molecular dynamics simulations, we study room temperature thermal conductivity of SiNWs with Li insertion. It is found that compared with the pristine SiNW, there is as much as 60% reduction in thermal conductivity with 10% concentration of inserted Li atoms, while under the same impurity concentration the reduction in thermal conductivity of the mass-disordered SiNW is only 30%. With lattice dynamics calculations and normal mode decomposition, it is revealed that the phonon lifetimes in SiNWs decrease greatly due to strong scattering of phonons by vibrational modes of Li atoms, especially for those high frequency phonons. The observed strong phonon scattering phenomenon in Li-inserted SiNWs is similar to the phonon rattling effect. Our study serves as an exploration of thermal properties of SiNWs as Li battery anodes or weakly coupled with impurity atoms.

  5. Effects of lithium insertion on thermal conductivity of silicon nanowires

    International Nuclear Information System (INIS)

    Recently, silicon nanowires (SiNWs) have been applied as high-performance Li battery anodes, since they can overcome the pulverization and mechanical fracture during lithiation. Although thermal stability is one of the most important parameters that determine safety of Li batteries, thermal conductivity of SiNWs with Li insertion remains unclear. In this letter, using molecular dynamics simulations, we study room temperature thermal conductivity of SiNWs with Li insertion. It is found that compared with the pristine SiNW, there is as much as 60% reduction in thermal conductivity with 10% concentration of inserted Li atoms, while under the same impurity concentration the reduction in thermal conductivity of the mass-disordered SiNW is only 30%. With lattice dynamics calculations and normal mode decomposition, it is revealed that the phonon lifetimes in SiNWs decrease greatly due to strong scattering of phonons by vibrational modes of Li atoms, especially for those high frequency phonons. The observed strong phonon scattering phenomenon in Li-inserted SiNWs is similar to the phonon rattling effect. Our study serves as an exploration of thermal properties of SiNWs as Li battery anodes or weakly coupled with impurity atoms

  6. Controlled 3D buckling of silicon nanowires for stretchable electronics.

    Science.gov (United States)

    Xu, Feng; Lu, Wei; Zhu, Yong

    2011-01-25

    Silicon (Si) nanowire (NW) coils were fabricated on elastomeric substrates by a controlled buckling process. Si NWs were first transferred onto prestrained and ultraviolet/ozone (UVO)-treated poly(dimethylsiloxane) (PDMS) substrates and buckled upon release of the prestrain. Two buckling modes (the in-plane wavy mode and the three-dimensional coiled mode) were found; a transition between them was achieved by controlling the UVO treatment of PDMS. Structural characterization revealed that the NW coils were oval-shaped. The oval-shaped NW coils exhibited very large stretchability up to the failure strain of PDMS (∼104% in our study). Such a large stretchability relies on the effectiveness of the coil shape in mitigating the maximum local strain, with a mechanics that is similar to the motion of a coil spring. Single NW devices based on coiled NWs were demonstrated with a nearly constant electrical response in a large strain range. In addition to the wavy shape, the coil shape represents an effective architecture in accommodating large tension, compression, bending, and twist, which may find important applications for stretchable electronics and other stretchable technologies. PMID:21189041

  7. A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor.

    Science.gov (United States)

    Lee, Jieun; Jang, Jaeman; Choi, Bongsik; Yoon, Jinsu; Kim, Jee-Yeon; Choi, Yang-Kyu; Kim, Dong Myong; Kim, Dae Hwan; Choi, Sung-Jin

    2015-01-01

    This study demonstrates a hybrid biosensor comprised of a silicon nanowire (SiNW) integrated with an amplifier MOSFET to improve the current response of field-effect-transistor (FET)-based biosensors. The hybrid biosensor is fabricated using conventional CMOS technology, which has the potential advantage of high density and low noise performance. The biosensor shows a current response of 5.74 decades per pH for pH detection, which is 2.5 × 10(5) times larger than that of a single SiNW sensor. In addition, we demonstrate charged polymer detection using the biosensor, with a high current change of 4.5 × 10(5) with a 500 nM concentration of poly(allylamine hydrochloride). In addition, we demonstrate a wide dynamic range can be obtained by adjusting the liquid gate voltage. We expect that this biosensor will be advantageous and practical for biosensor applications which requires lower noise, high speed, and high density. PMID:26197105

  8. Electronic transport mechanisms in scaled gate-all-around silicon nanowire transistor arrays

    International Nuclear Information System (INIS)

    Low-frequency noise is used to study the electronic transport in arrays of 14 nm gate length vertical silicon nanowire devices. We demonstrate that, even at such scaling, the electrostatic control of the gate-all-around is sufficient in the sub-threshold voltage region to confine charges in the heart of the wire, and the extremely low noise level is comparable to that of high quality epitaxial layers. Although contact noise can already be a source of poor transistor operation above threshold voltage for few nanowires, nanowire parallelization drastically reduces its impact

  9. Nanowire-integrated microporous silicon membrane for continuous fluid transport in micro cooling device

    International Nuclear Information System (INIS)

    We report an efficient passive micro pump system combining the physical properties of nanowires and micropores. This nanowire-integrated microporous silicon membrane was created to feed coolant continuously onto the surface of the wick in a micro cooling device to ensure it remains hydrated and in case of dryout, allow for regeneration of the system. The membrane was fabricated by photoelectrochemical etching to form micropores followed by hydrothermal growth of nanowires. This study shows a promising approach to address thermal management challenges for next generation electronic devices with absence of external power

  10. Structural and optical properties of axial silicon-germanium nanowire heterojunctions

    International Nuclear Information System (INIS)

    Detailed studies of the structural and optical properties of axial silicon-germanium nanowire heterojunctions show that despite the 4.2% lattice mismatch between Si and Ge they can be grown without a significant density of structural defects. The lattice mismatch induced strain is partially relieved due to spontaneous SiGe intermixing at the heterointerface during growth and lateral expansion of the Ge segment of the nanowire. The mismatch in Ge and Si coefficients of thermal expansion and low thermal conductivity of Si/Ge nanowire heterojunctions are proposed to be responsible for the thermally induced stress detected under intense laser radiation in photoluminescence and Raman scattering measurements

  11. Structural and optical properties of axial silicon-germanium nanowire heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Tsybeskov, L., E-mail: tsybesko@njit.edu [ECE Department, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Kamins, T. I. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Wu, X.; Lockwood, D. J. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada)

    2015-12-21

    Detailed studies of the structural and optical properties of axial silicon-germanium nanowire heterojunctions show that despite the 4.2% lattice mismatch between Si and Ge they can be grown without a significant density of structural defects. The lattice mismatch induced strain is partially relieved due to spontaneous SiGe intermixing at the heterointerface during growth and lateral expansion of the Ge segment of the nanowire. The mismatch in Ge and Si coefficients of thermal expansion and low thermal conductivity of Si/Ge nanowire heterojunctions are proposed to be responsible for the thermally induced stress detected under intense laser radiation in photoluminescence and Raman scattering measurements.

  12. Preparation of silicon@silicon oxide core-shell nanowires from a silica precursor toward a high energy density Li-ion battery anode.

    Science.gov (United States)

    Zhang, Chuanjian; Gu, Lin; Kaskhedikar, Nitin; Cui, Guanglei; Maier, Joachim

    2013-12-11

    Bulk-quantity silicon@silicon oxide nanowires have been successfully synthesized via a facile high-temperature approach using environment-friendly silica mixed with titanium powders. It is confirmed that the obtained nanowires process a crystalline core and amorphous oxide sheath. The obtained nanowires grow along the [111] direction which catalyzed by spherical silicon@siilcon oxide nanoparticles. The unique one-dimensional structure and thin oxide sheath result in the favorable electrochemical performances, which may be beneficial to the high energy density silicon anode for lithium ion batteries. PMID:24229329

  13. Synthesis, Characterization and Kinetics of Epitaxial-Oriented Silicon Nanowire Arrays on Si Substrates

    Science.gov (United States)

    Wang, Z. L.; Bao, J. K.; Wan, Y. T.; Xia, W. W.; Wang, Y. W.; Sha, J.

    The fabrication of vertical-oriented, high aspect ratio silicon nanowires (SiNWs) with controllable density and length is of interest for the development of nanowire-based electronics and photovoltaic devices. Here we reported a both simple and economical method for synthesizing large-area epitaxial-oriented SiNW arrays, which was achieved on the Si (111) substrates by Au catalyzed vapor-liquid-solid mechanism using the conventional chemical vapor deposition furnace system. Their morphologies and microstructures were investigated with scanning electron microscopy and transmission electron microscopy, respectively. The results showed that most of nanowires were vertically grown on substrates, their density and length can be well controlled. As-grown SiNW is composed of a single crystalline silicon core and a thin amorphous silicon oxide coating layer. Furthermore, their growth kinetics was discussed in detail. It indicates that there are both the substrate-nanowire Si adatom surface diffusion and the slight radial growth during the upgrowth of nanowire, and besides, the migration of Au on the sidewall of nanowire was also found for such epitaxial-oriental SiNWs.

  14. Multichannel nonlinear distortion compensation using optical phase conjugation in a silicon nanowire

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Schoerder, Jochen; Da Ros, Francesco;

    2015-01-01

    We experimentally demonstrate compensation of nonlinear distortion caused by the Kerr effect in a 3 x 32-Gbaud quadrature phase-shift keying (QPSK) wavelength-division multiplexing (WDM) transmission system. We use optical phase conjugation (OPC) produced by four-wave mixing (FWM) in a 7-mm long...... silicon nanowire. A clear improvement in Q-factor is shown after 800-km transmission with high span input power when comparing the system with and without the optical phase conjugation module. The influence of OSNR degradation introduced by the silicon nanowire is analysed by comparing transmission...... systems of three different lengths. This is the first demonstration of nonlinear compensation using a silicon nanowire. (C)2015 Optical Society of America...

  15. Vertically aligned nanowires on flexible silicone using a supported alumina template prepared by pulsed anodization

    DEFF Research Database (Denmark)

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

    2009-01-01

    Carpets of vertically aligned nanowires on flexible substrates are successfully realized by a template method. Applying special pulsed anodization conditions, defect-free nanoporous alumina structures supported on polydimethylsiloxane (PDMS), a flexible silicone elastomer, are created. By using t...... this template with nanopores ending on a conducting underlayer, a high-density nanowire array can be simply grown by direct DCelectrodeposition on the top of the silicone rubber. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.......Carpets of vertically aligned nanowires on flexible substrates are successfully realized by a template method. Applying special pulsed anodization conditions, defect-free nanoporous alumina structures supported on polydimethylsiloxane (PDMS), a flexible silicone elastomer, are created. By using...

  16. Fabrication of carbon-coated silicon nanowires and their application in dye-sensitized solar cells.

    Science.gov (United States)

    Kim, Junhee; Lim, Jeongmin; Kim, Minsoo; Lee, Hae-Seok; Jun, Yongseok; Kim, Donghwan

    2014-11-12

    We report the fabrication of silicon/carbon core/shell nanowire arrays using a two-step process, involving electroless metal deposition and chemical vapor deposition. In general, foreign shell materials that sheath core materials change the inherent characteristics of the core materials. The carbon coating functionalized the silicon nanowire arrays, which subsequently showed electrocatalytic activities for the reduction of iodide/triiodide. This was verified by cyclic voltammetry and electrochemical impedance spectroscopy. We employed the carbon-coated silicon nanowire arrays in dye-sensitized solar cells as counter electrodes. We optimized the carbon shells to maximize the photovoltaic performance of the resulting devices, and subsequently, a peak power conversion efficiency of 9.22% was achieved. PMID:25319204

  17. Multiple Silicon Nanowires with Enzymatic Modification for Measuring Glucose Concentration

    Directory of Open Access Journals (Sweden)

    Cheng-Chih Hsu

    2015-08-01

    Full Text Available This study fabricated a multiple poly-Si nanowires sensor through a top-down method and immobilized glucose oxidase on the multiple nanowires for determining glucose concentration. The proposed sensor is 340 nm in width and uses five physically identical and parallel nanowires. The sensor contained nanowires of various lengths (3, 5, and 10 μm. Experimental results showed that sensor sensitivity is inversely proportional to nanowire length. The sensor with 3 μm in nanowire length exhibited a theoretical resolution of 0.003 mg/dL and the highest sensitivity of 0.03 μA/(mg/dL. Furthermore, the proposed sensor retains this performance when reused for up to 10 applications.

  18. Effect of nanowire length on the performance of silicon nanowires based solar cell

    International Nuclear Information System (INIS)

    Currently, silicon nanowires (SiNWs) are attracting attention as promising candidate materials for developing the next-generation solar cells to realize both low cost and high efficiency due to their unique structural, electrical, and optical properties. In this paper, a vertical-aligned SiNWs array has been prepared by metal-assistant chemical etching technique and implemented on SiNW array textured solar cells for photovoltaic application. The shape and size of SiNWs were controlled by etching time of 30 min, 45 min and 60 min with the length of SiNWs of 4 μm, 6 μm and 8 μm, respectively. The etching rate was estimated to be about 133 nm per minute. The optical properties of a SiNWs array with different lengths were investigated in terms of optical reflection property. Less than 6% reflection ratio from 300 nm to 800 nm wavelength was achieved. In addition, I–V characteristic was used to estimate the dependence of the SiNWs length on the performance of SiNWs based solar cell. Conservation efficiencies were achieved of 1.71%, 2.19%, and 2.39% corresponding to 4 μm, 6 μm and 8 μm SiNWs in length, respectively. (paper)

  19. Interference lithographically defined and catalytically etched, large-area silicon nanocones from nanowires.

    Science.gov (United States)

    Dawood, M K; Liew, T H; Lianto, P; Hong, M H; Tripathy, S; Thong, J T L; Choi, W K

    2010-05-21

    We report a simple and cost effective method for the synthesis of large-area, precisely located silicon nanocones from nanowires. The nanowires were obtained from our interference lithography and catalytic etching (IL-CE) method. We found that porous silicon was formed near the Au catalyst during the fabrication of the nanowires. The porous silicon exhibited enhanced oxidation ability when exposed to atmospheric conditions or in wet oxidation ambient. Very well located nanocones with uniform sharpness resulted when these oxidized nanowires were etched in 10% HF. Nanocones of different heights were obtained by varying the doping concentration of the silicon wafers. We believe this is a novel method of producing large-area, low cost, well defined nanocones from nanowires both in terms of the control of location and shape of the nanocones. A wide range of potential applications of the nanocone array can be found as a master copy for nanoimprinted polymer substrates for possible biomedical research; as a candidate for making sharp probes for scanning probe nanolithography; or as a building block for field emitting tips or photodetectors in electronic/optoelectronic applications. PMID:20418606

  20. Carbon−Silicon Core−Shell Nanowires as High Capacity Electrode for Lithium Ion Batteries

    KAUST Repository

    Cui, Li-Feng

    2009-09-09

    We introduce a novel design of carbon-silicon core-shell nanowires for high power and long life lithium battery electrodes. Amorphous silicon was coated onto carbon nanofibers to form a core-shell structure and the resulted core-shell nanowires showed great performance as anode material. Since carbon has a much smaller capacity compared to silicon, the carbon core experiences less structural stress or damage during lithium cycling and can function as a mechanical support and an efficient electron conducting pathway. These nanowires have a high charge storage capacity of ∼2000 mAh/g and good cycling life. They also have a high Coulmbic efficiency of 90% for the first cycle and 98-99.6% for the following cycles. A full cell composed of LiCoO2 cathode and carbon-silicon core-shell nanowire anode is also demonstrated. Significantly, using these core-shell nanowires we have obtained high mass loading and an area capacity of ∼4 mAh/cm2, which is comparable to commercial battery values. © 2009 American Chemical Society.

  1. Solution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes

    KAUST Repository

    Chan, Candace K.

    2010-03-23

    Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires using the pyrolysis of sugar was found to be crucial for making good electronic contact to the material. Using multiwalled carbon nanotubes as the conducting additive was found to be more effective for obtaining good cycling behavior than using amorphous carbon. Reversible capacities of 1500 mAh/g were observed for 30 cycles. © 2010 American Chemical Society.

  2. Coaxial-structured ZnO/silicon nanowires extended-gate field-effect transistor as pH sensor

    International Nuclear Information System (INIS)

    An extended-gate field-effect transistor (EGFET) of coaxial-structured ZnO/silicon nanowires as pH sensor was demonstrated in this paper. The oriented 1-μm-long silicon nanowires with the diameter of about 50 nm were vertically synthesized by the electroless metal deposition method at room temperature and were sequentially capped with the ZnO films using atomic layer deposition at 50 °C. The transfer characteristics (IDS–VREF) of such ZnO/silicon nanowire EGFET sensor exhibited the sensitivity and linearity of 46.25 mV/pH and 0.9902, respectively for the different pH solutions (pH 1–pH 13). In contrast to the ZnO thin-film ones, the ZnO/silicon nanowire EGFET sensor achieved much better sensitivity and superior linearity. It was attributed to a high surface-to-volume ratio of the nanowire structures, reflecting a larger effective sensing area. The output voltage and time characteristics were also measured to indicate good reliability and durability for the ZnO/silicon nanowires sensor. Furthermore, the hysteresis was 9.74 mV after the solution was changed as pH 7 → pH 3 → pH 7 → pH 11 → pH 7. - Highlights: ► Coaxial-structured ZnO/silicon nanowire EGFET was demonstrated as pH sensor. ► EMD and ALD methods were proposed to fabricate ZnO/silicon nanowires. ► ZnO/silicon nanowire EGFET sensor achieved better sensitivity and linearity. ► ZnO/silicon nanowire EGFET sensor had good reliability and durability

  3. Microstructures of the silicon carbide nanowires obtained by annealing the mechanically-alloyed amorphous powders

    International Nuclear Information System (INIS)

    Silicon, graphite and boron nitride powders were mechanically alloyed for 40 h in argon. The as-milled powders were annealed at 1700 °C in nitrogen for 30 min. The annealed powders are covered by a thick layer of gray–green SiC nanowires, which are 300 nm to 1000 nm in diameter and several hundred microns in length. Trace iron in the raw powders acts as a catalyst, promoting the V–L–S process. It follows that the actual substances contributing to the growth of the SiC nanowires may be silicon, graphite and the metal impurities in the raw powders. The results from HRTEM and XRD reveal that the products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. It is interestingly found that 6H–SiC coexists with 3C–SiC in one nodular nanowire. This novel structure may introduce periodic potential field along the longitudinal direction of the nanowires, and may find applications in the highly integrated optoelectronic devices. - Graphical abstract: Display Omitted - Highlights: • SiC nanowires were prepared by annealing the mechanically alloyed amorphous powders. • SiC nanowires are 300 nm to 1000 nm in diameter and several hundred microns in length. • The products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. • Trace Fe in the raw powders acts as a catalyst, promoting the V–L–S process. • 6H–SiC coexists with 3C–SiC in one nodular SiC nanowire

  4. Microstructures of the silicon carbide nanowires obtained by annealing the mechanically-alloyed amorphous powders

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei, E-mail: zhangpengfei1984@163.com; Li, Xinli

    2015-07-15

    Silicon, graphite and boron nitride powders were mechanically alloyed for 40 h in argon. The as-milled powders were annealed at 1700 °C in nitrogen for 30 min. The annealed powders are covered by a thick layer of gray–green SiC nanowires, which are 300 nm to 1000 nm in diameter and several hundred microns in length. Trace iron in the raw powders acts as a catalyst, promoting the V–L–S process. It follows that the actual substances contributing to the growth of the SiC nanowires may be silicon, graphite and the metal impurities in the raw powders. The results from HRTEM and XRD reveal that the products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. It is interestingly found that 6H–SiC coexists with 3C–SiC in one nodular nanowire. This novel structure may introduce periodic potential field along the longitudinal direction of the nanowires, and may find applications in the highly integrated optoelectronic devices. - Graphical abstract: Display Omitted - Highlights: • SiC nanowires were prepared by annealing the mechanically alloyed amorphous powders. • SiC nanowires are 300 nm to 1000 nm in diameter and several hundred microns in length. • The products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. • Trace Fe in the raw powders acts as a catalyst, promoting the V–L–S process. • 6H–SiC coexists with 3C–SiC in one nodular SiC nanowire.

  5. Top-Down Nanofabrication and Characterization of 20 nm Silicon Nanowires for Biosensing Applications.

    Science.gov (United States)

    M N, M Nuzaihan; Hashim, U; Md Arshad, M K; Ruslinda, A Rahim; Rahman, S F A; Fathil, M F M; Ismail, Mohd H

    2016-01-01

    A top-down nanofabrication approach is used to develop silicon nanowires from silicon-on-insulator (SOI) wafers and involves direct-write electron beam lithography (EBL), inductively coupled plasma-reactive ion etching (ICP-RIE) and a size reduction process. To achieve nanometer scale size, the crucial factors contributing to the EBL and size reduction processes are highlighted. The resulting silicon nanowires, which are 20 nm in width and 30 nm in height (with a triangular shape) and have a straight structure over the length of 400 μm, are fabricated precisely at the designed location on the device. The device is applied in biomolecule detection based on the changes in drain current (Ids), electrical resistance and conductance of the silicon nanowires upon hybridization to complementary target deoxyribonucleic acid (DNA). In this context, the scaled-down device exhibited superior performances in terms of good specificity and high sensitivity, with a limit of detection (LOD) of 10 fM, enables for efficient label-free, direct and higher-accuracy DNA molecules detection. Thus, this silicon nanowire can be used as an improved transducer and serves as novel biosensor for future biomedical diagnostic applications. PMID:27022732

  6. Fabrication, electrical characterization and scanning gate microscopy of Schottky silicon nanowire devices

    Science.gov (United States)

    Melinte, Sorin; Iordanescu, Andra; Dutu, Constantin; Flandre, Denis; Faniel, Sebastien; Martins, Frederico; Hackens, Benoit; ICTM Team; IMCN Team

    2013-03-01

    We report the fabrication and the electrical characterization of Schottky silicon nanowire field effect transistors. Our devices are built with a top down approach on silicon-on-insulator wafers with (100) crystallographic orientation and 10 - 25 Ω.cm resistivity of the silicon top layer. The transistor's channel is assured by silicon nanowires patterned by electron beam lithography and wet etching. The nanowires have nominal cross sections down to 30 × 30nm2 . For example, platinum-silicon Schottky contacts are made by physical deposition of a platinum layer followed by an annealing at 500°C for 2 minutes in a N2 atmosphere. The devices are characterized at various temperatures by current-voltage measurements and scanning gate microscopy techniques. Varying the dimensionality and geometry of the contacts, the nature of metal-semiconductor junctions and the substrate strain, we get new insights into the influence of trapped charges at the Si -SiO2 interface on transport through SiO2-enclosed nanowires, at the nanometer scale.

  7. A silicon carbide nanowire field effect transistor for DNA detection

    Science.gov (United States)

    Fradetal, L.; Bano, E.; Attolini, G.; Rossi, F.; Stambouli, V.

    2016-06-01

    This work reports on the label-free electrical detection of DNA molecules for the first time, using silicon carbide (SiC) as a novel material for the realization of nanowire field effect transistors (NWFETs). SiC is a promising semiconductor for this application due to its specific characteristics such as chemical inertness and biocompatibility. Non-intentionally n-doped SiC NWs are first grown using a bottom-up vapor–liquid–solid (VLS) mechanism, leading to the NWs exhibiting needle-shaped morphology, with a length of approximately 2 μm and a diameter ranging from 25 to 60 nm. Then, the SiC NWFETs are fabricated and functionalized with DNA molecule probes via covalent coupling using an amino-terminated organosilane. The drain current versus drain voltage (I d–V d) characteristics obtained after the DNA grafting and hybridization are reported from the comparative and simultaneous measurements carried out on the SiC NWFETs, used either as sensors or references. As a representative result, the current of the sensor is lowered by 22% after probe DNA grafting and by 7% after target DNA hybridization, while the current of the reference does not vary by more than ±0.6%. The current decrease confirms the field effect induced by the negative charges of the DNA molecules. Moreover, the selectivity, reproducibility, reversibility and stability of the studied devices are emphasized by de-hybridization, non-complementary hybridization and re-hybridization experiments. This first proof of concept opens the way for future developments using SiC-NW-based sensors.

  8. A silicon carbide nanowire field effect transistor for DNA detection.

    Science.gov (United States)

    Fradetal, L; Bano, E; Attolini, G; Rossi, F; Stambouli, V

    2016-06-10

    This work reports on the label-free electrical detection of DNA molecules for the first time, using silicon carbide (SiC) as a novel material for the realization of nanowire field effect transistors (NWFETs). SiC is a promising semiconductor for this application due to its specific characteristics such as chemical inertness and biocompatibility. Non-intentionally n-doped SiC NWs are first grown using a bottom-up vapor-liquid-solid (VLS) mechanism, leading to the NWs exhibiting needle-shaped morphology, with a length of approximately 2 μm and a diameter ranging from 25 to 60 nm. Then, the SiC NWFETs are fabricated and functionalized with DNA molecule probes via covalent coupling using an amino-terminated organosilane. The drain current versus drain voltage (I d-V d) characteristics obtained after the DNA grafting and hybridization are reported from the comparative and simultaneous measurements carried out on the SiC NWFETs, used either as sensors or references. As a representative result, the current of the sensor is lowered by 22% after probe DNA grafting and by 7% after target DNA hybridization, while the current of the reference does not vary by more than ±0.6%. The current decrease confirms the field effect induced by the negative charges of the DNA molecules. Moreover, the selectivity, reproducibility, reversibility and stability of the studied devices are emphasized by de-hybridization, non-complementary hybridization and re-hybridization experiments. This first proof of concept opens the way for future developments using SiC-NW-based sensors. PMID:27120971

  9. Patterned micropads made of copper nanowires on silicon substrate for application as chip to substrate interconnects

    International Nuclear Information System (INIS)

    Patterned micropads made of metallic nanowires, 50 μm in diameter, are fabricated on a silicon substrate. An aluminium film patterned with SiO2 is anodized to fabricate a patterned nanoporous alumina (PNA) template in which metallic nanowires are electrodeposited. SiO2 that is deposited using the plasma-enhanced chemical vapour deposition process is demonstrated to be an effective barrier to anodization for the fabrication of high aspect ratio PNA templates. Current-voltage characteristics of an individual copper nanowire micropad display ohmic behaviour with a low resistance value of 5.5 mΩ. The nanowires are able to withstand the solder reflow process. Cu nanowire/Sn solder reflow reaction leads to Cu6Sn5 intermetallic formation. These micropads made of metallic nanowires have the potential for application as chip to substrate interconnects. Nanostructure synthesis is carried out using standard microelectronics fabrication techniques that would enable easy integration of such nanodevices into routine silicon manufacturing

  10. Dopant profiling and surface analysis of silicon nanowires using capacitance-voltage measurements.

    Science.gov (United States)

    Garnett, Erik C; Tseng, Yu-Chih; Khanal, Devesh R; Wu, Junqiao; Bokor, Jeffrey; Yang, Peidong

    2009-05-01

    Silicon nanowires are expected to have applications in transistors, sensors, resonators, solar cells and thermoelectric systems. Understanding the surface properties and dopant distribution will be critical for the fabrication of high-performance devices based on nanowires. At present, determination of the dopant concentration depends on a combination of experimental measurements of the mobility and threshold voltage in a nanowire field-effect transistor, a calculated value for the capacitance, and two assumptions--that the dopant distribution is uniform and that the surface (interface) charge density is known. These assumptions can be tested in planar devices with the capacitance-voltage technique. This technique has also been used to determine the mobility of nanowires, but it has not been used to measure surface properties and dopant distributions, despite their influence on the electronic properties of nanowires. Here, we measure the surface (interface) state density and the radial dopant profile of individual silicon nanowire field-effect transistors with the capacitance-voltage technique. PMID:19421217

  11. Carbon-assisted growth and high visible-light optical reflectivity of amorphous silicon oxynitride nanowires

    Directory of Open Access Journals (Sweden)

    Tang Zirong

    2011-01-01

    Full Text Available Abstract Large amounts of amorphous silicon oxynitride nanowires have been synthesized on silicon wafer through carbon-assisted vapor-solid growth avoiding the contamination from metallic catalysts. These nanowires have the length of up to 100 μm, with a diameter ranging from 50 to 150 nm. Around 3-nm-sized nanostructures are observed to be homogeneously distributed within a nanowire cross-section matrix. The unique configuration might determine the growth of ternary amorphous structure and its special splitting behavior. Optical properties of the nanowires have also been investigated. The obtained nanowires were attractive for their exceptional whiteness, perceived brightness, and optical brilliance. These nanowires display greatly enhanced reflection over the whole visible wavelength, with more than 80% of light reflected on most of the wavelength ranging from 400 to 700 nm and the lowest reflectivity exceeding 70%, exhibiting performance superior to that of the reported white beetle. Intense visible photoluminescence is also observed over a broad spectrum ranging from 320 to 500 nm with two shoulders centered at around 444 and 468 nm, respectively.

  12. Synthesis of β-SiC nanowires by ball milled nanoparticles of silicon and carbon

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Pengchao, E-mail: kangpc@hit.edu.cn [Materials Science and Engineering School, Harbin Institute of Technology, P.O.B. 433, Harbin 150001 (China); Zhang, Bin; Wu, Gaohui; Gou, Huasong; Chen, Guoqin; Jiang, Longtao [Materials Science and Engineering School, Harbin Institute of Technology, P.O.B. 433, Harbin 150001 (China); Mula, Suhrit [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2014-08-01

    Highlights: • The β-SiC nanowires were synthesized only use milled Si and C nanoparticles. • No catalyst was used in this process. • The grown mechanism of β-SiC nanowires is nanoparticles self-assembly and solid–solid reaction. • This notion, together with the nanowires synthesis are expected to apply opens up other semiconductor nanomaterials. - Abstract: In the present investigation, we report a simple and new technique to synthesize silicon carbide nanowires by high energy ball milling of silicon and carbon powders followed by annealing at elevated temperatures. The detailed structural analysis was carried out by X-ray diffraction, scanning and transmission electron microscopy, and FT-IR analysis. Nanocrystalline silicon particles were detected to be covered by amorphous carbon after milling. This typical structure was transformed to β-SiC nanowires during annealing by new growth mechanism. The β-SiC nanoparticles were found to be self-assembled one by one and formed a curly chain, and then rotated gradually in accordance to the same crystal orientation along the β-SiC [1 1 1] direction.

  13. Novel synthetic methodology for controlling the orientation of zinc oxide nanowires grown on silicon oxide substrates.

    Science.gov (United States)

    Cho, Jinhyun; Salleh, Najah; Blanco, Carlos; Yang, Sungwoo; Lee, Chul-Jin; Kim, Young-Woo; Kim, Jungsang; Liu, Jie

    2014-04-01

    This study presents a simple method to reproducibly obtain well-aligned vertical ZnO nanowire arrays on silicon oxide (SiOx) substrates using seed crystals made from a mixture of ammonium hydroxide (NH4OH) and zinc acetate (Zn(O2CCH3)2) solution. In comparison, high levels of OH(-) concentration obtained using NaOH or KOH solutions lead to incorporation of Na or K atoms into the seed crystals, destroying the c-axis alignment of the seeds and resulting in the growth of misaligned nanowires. The use of NH4OH eliminates the metallic impurities and ensures aligned nanowire growth in a wide range of OH(-) concentrations in the seed solution. The difference of crystalline orientations between NH4OH- and NaOH-based seeds is directly observed by lattice-resolved images and electron diffraction patterns using a transmission electron microscope (TEM). This study obviously suggests that metallic impurities incorporated into the ZnO nanocrystal seeds are one of the factors that generates the misaligned ZnO nanowires. This method also enables the use of silicon oxide substrates for the growth of vertically aligned nanowires, making ZnO nanostructures compatible with widely used silicon fabrication technology. PMID:24584438

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

    International Nuclear Information System (INIS)

    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.

  15. Monolithic single GaN nanowire laser with photonic crystal microcavity on silicon

    International Nuclear Information System (INIS)

    Optically pumped lasing at room temperature in a silicon based monolithic single GaN nanowire with a two-dimensional photonic crystal microcavity is demonstrated. Catalyst-free nanowires with low density (∼108 cm-2) are grown on Si by plasma-assisted molecular beam epitaxy. High resolution transmission electron microscopy images reveal that the nanowires are of wurtzite structure and they have no observable defects. A single nanowire laser fabricated on Si is characterized by a lasing transition at λ=371.3 nm with a linewidth of 0.55 nm. The threshold is observed at a pump power density of ∼120 kW/cm2 and the spontaneous emission factor β is estimated to be 0.08.

  16. Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method

    Science.gov (United States)

    Ouertani, Rachid; Hamdi, Abderrahmen; Amri, Chohdi; Khalifa, Marouan; Ezzaouia, Hatem

    2014-10-01

    In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

  17. Growth Mechanism of Cubic-Silicon Carbide Nanowires

    Directory of Open Access Journals (Sweden)

    K. Y. Cheong

    2009-01-01

    Full Text Available Cubic-SiC nanowires were synthesized using activated carbon powder and Si substrate in vacuum at 1200–1350°C for 1–4 hours. The nanowires were grown according to the following proposed mechanisms: (1 diffusion of C/CO into Si substrate, (2 weakening of Si bond and atomic kick-out, (3 formation of Si-C in vapor phase, (4 formation of saturated SiC layer, (5 formation of pyramid-like SiC nanostructure, and (6 formation of SiC nanowires.

  18. Silicon Nanowires Grown on Metal Substrates via Self-Catalyst Mechanism

    Czech Academy of Sciences Publication Activity Database

    Dřínek, Vladislav; Klementová, Mariana; Fajgar, Radek; Dytrych, Pavel

    2015-01-01

    Roč. 160, DEC 1 (2015), s. 109-112. ISSN 0167-577X R&D Projects: GA ČR GA13-25747S Institutional support: RVO:67985858 ; RVO:68378271 Keywords : CVD * silicon * nanowire Subject RIV: CA - Inorganic Chemistry Impact factor: 2.489, year: 2014

  19. Functionalization and microfluidic integration of silicon nanowire biologically gated field effect transistors

    DEFF Research Database (Denmark)

    Pfreundt, Andrea

    This thesis deals with the development of a novel biosensor for the detection of biomolecules based on a silicon nanowire biologically gated field-effect transistor and its integration into a point-of-care device. The sensor and electrical on-chip integration was developed in a different project...

  20. Specific and reversible immobilization of histidine-tagged proteins on functionalized silicon nanowires

    DEFF Research Database (Denmark)

    Liu, Yi-Chi; Rieben, Nathalie Ines; Iversen, Lars;

    2010-01-01

    Silicon nanowire (Si NW)-based field effect transistors (FETs) have shown great potential as biosensors (bioFETs) for ultra-sensitive and label-free detection of biomolecular interactions. Their sensitivity depends not only on the device properties, but also on the function of the biological reco...

  1. IC Compatible Wafer Level Fabrication of Silicon Nanowire Field Effect Transistors for Biosensing Applications

    NARCIS (Netherlands)

    Moh, T.S.Y.

    2013-01-01

    In biosensing, nano-devices such as Silicon Nanowire Field Effect Transistors (SiNW FETs) are promising components/sensors for ultra-high sensitive detection, especially when samples are low in concentration or a limited volume is available. Current processing of SiNW FETs often relies on expensive

  2. Gamma ray irradiated silicon nanowires: An effective model to investigate defects at the interface of Si/SiOx

    International Nuclear Information System (INIS)

    The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. 29Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q4 unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx

  3. Gamma ray irradiated silicon nanowires: An effective model to investigate defects at the interface of Si/SiOx

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Kui; Zhao, Yi; Liu, Liangbin; Lee, Shuit-Tong; Shao, Mingwang, E-mail: wxlthefirst@gmail.com, E-mail: xuegi@nju.edu.cn, E-mail: mwshao@suda.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation, Center of Suzhou Nano Science and Technology, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123 (China); Wang, Xiaoliang, E-mail: wxlthefirst@gmail.com, E-mail: xuegi@nju.edu.cn, E-mail: mwshao@suda.edu.cn; Xue, Gi, E-mail: wxlthefirst@gmail.com, E-mail: xuegi@nju.edu.cn, E-mail: mwshao@suda.edu.cn [State Key Laboratory of Co-ordination Chemistry, Department of Polymer Science and Engineering, Nanjing University, No. 20, Hankou Road, Nanjing 210093 (China)

    2014-01-20

    The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. {sup 29}Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q{sup 4} unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx.

  4. Charged impurity scattering and mobility in gated silicon nanowires

    OpenAIRE

    Persson, Martin P.; Mera, Hector; Niquet, Yann-Michel; Delerue, Christophe; Diarra, Mamadou

    2010-01-01

    We study the effects of charged impurity scattering on the electronic transport properties of -oriented Si nanowires in a gate-all-around geometry, where the impurity potential is screened by the gate, gate oxide and conduction band electrons. The electronic structure of the doped nanowires is calculated with a tight-binding method and the transport properties with a Landauer-Buttiker Green functions approach and the linearized Boltzmann transport equation (LBTE) in the first Born approximati...

  5. Fabrication of a Silicon Nanowire on a Bulk Substrate by Use of a Plasma Etching and Total Ionizing Dose Effects on a Gate-All-Around Field-Effect Transistor

    Science.gov (United States)

    Moon, Dong-Il; Han, Jin-Woo; Meyyappan, Meyya

    2016-01-01

    The gate all around transistor is investigated through experiment. The suspended silicon nanowire for the next generation is fabricated on bulk substrate by plasma etching method. The scallop pattern generated by Bosch process is utilized to form a floating silicon nanowire. By combining anisotropic and istropic silicon etch process, the shape of nanowire is accurately controlled. From the suspended nanowire, the gate all around transistor is demonstrated. As the silicon nanowire is fully surrounded by the gate, the device shows excellent electrostatic characteristics.

  6. Crystalline-Amorphous Core−Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes

    KAUST Repository

    Cui, Li-Feng

    2009-01-14

    Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon\\'s large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline- amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li ions. We demonstrate here that these core-shell nanowires have high charge storage capacity (̃1000 mAh/g, 3 times of carbon) with ̃90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, ̃20 times of carbon at 1 h rate). © 2009 American Chemical Society.

  7. Monolithic electrically injected nanowire array edge-emitting laser on (001) silicon

    KAUST Repository

    Frost, Thomas

    2014-08-13

    A silicon-based laser, preferably electrically pumped, has long been a scientific and engineering goal. We demonstrate here, for the first time, an edge-emitting InGaN/GaN disk-in-nanowire array electrically pumped laser emitting in the green (λ = 533 nm) on (001) silicon substrate. The devices display excellent dc and dynamic characteristics with values of threshold current density, differential gain, T0 and small signal modulation bandwidth equal to 1.76 kA/cm2, 3 × 10-17 cm2, 232 K, and 5.8 GHz respectively under continuous wave operation. Preliminary reliability measurements indicate a lifetime of 7000 h. The emission wavelength can be tuned by varying the alloy composition in the quantum disks. The monolithic nanowire laser on (001)Si can therefore address wide-ranging applications such as solid state lighting, displays, plastic fiber communication, medical diagnostics, and silicon photonics. © 2014 American Chemical Society.

  8. Fabrication and Photovoltaic Characteristics of Coaxial Silicon Nanowire Solar Cells Prepared by Wet Chemical Etching

    Directory of Open Access Journals (Sweden)

    Chien-Wei Liu

    2012-01-01

    Full Text Available Nanostructured solar cells with coaxial p-n junction structures have strong potential to enhance the performances of the silicon-based solar cells. This study demonstrates a radial junction silicon nanowire (RJSNW solar cell that was fabricated simply and at low cost using wet chemical etching. Experimental results reveal that the reflectance of the silicon nanowires (SNWs declines as their length increases. The excellent light trapping was mainly associated with high aspect ratio of the SNW arrays. A conversion efficiency of ∼7.1% and an external quantum efficiency of ∼64.6% at 700 nm were demonstrated. Control of etching time and diffusion conditions holds great promise for the development of future RJSNW solar cells. Improving the electrode/RJSNW contact will promote the collection of carries in coaxial core-shell SNW array solar cells.

  9. Hydrophobic recovery in ultrathin PDMS-coated long and short silicon nanowires

    Science.gov (United States)

    Ganta, D.; Marry, C.; Ma, J.; Sinha, S.

    2016-03-01

    The ability to modify the contact angle (CA) of water on silicon has applications ranging from thermal management of electronics to miniaturized biomedical devices. Here, we report ∼30 ± 1° variation in superhydrophobic CA on silicon nanowires (NWs) coated with few nm of polydimethylsiloxane (PDMS), using a simple and stable plasma treatment. The variation in CA arises from choosing NWs of different lengths. We characterize the surfaces using a combination of X-ray photoelectron spectroscopy and other techniques. Together with CA available from similar treatment on bulk silicon, it is possible to non-lithographically create regions of diverse CA, from ∼5 to 149 ± 1°.

  10. Enhanced lithium ion battery cycling of silicon nanowire anodes by template growth to eliminate silicon underlayer islands.

    Science.gov (United States)

    Cho, Jeong-Hyun; Picraux, S Tom

    2013-01-01

    It is well-known that one-dimensional nanostructures reduce pulverization of silicon (Si)-based anode materials during Li ion cycling because they allow lateral relaxation. However, even with improved designs, Si nanowire-based structures still exhibit limited cycling stability for extended numbers of cycles, with the specific capacity retention with cycling not showing significant improvements over commercial carbon-based anode materials. We have found that one important reason for the lack of long cycling stability can be the presence of milli- and microscale Si islands which typically form under nanowire arrays during their growth. Stress buildup in these Si island underlayers with cycling results in cracking, and the loss of specific capacity for Si nanowire anodes, due to progressive loss of contact with current collectors. We show that the formation of these parasitic Si islands for Si nanowires grown directly on metal current collectors can be avoided by growth through anodized aluminum oxide templates containing a high density of sub-100 nm nanopores. Using this template approach we demonstrate significantly enhanced cycling stability for Si nanowire-based lithium-ion battery anodes, with retentions of more than ~1000 mA·h/g discharge capacity over 1100 cycles. PMID:24144166

  11. Novel junctionless silicon-oxide-nitride-oxide-silicon memory devices with field-enhanced poly-Si nanowire structure

    Science.gov (United States)

    Chou, Chia-Hsin; Chan, Wei-Sheng; Wu, Chun-Yu; Lee, I.-Che; Liao, Ta-Chuan; Wang, Chao-Lung; Wang, Kuang-Yu; Cheng, Huang-Chung

    2015-08-01

    In this work, a novel gate-all-around (GAA) low-temperature poly-Si (LTPS) junctionless (JL) silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory device with a field-enhanced nanowire (NW) structure has been proposed to improve the programing/erasing (P/E) performance. Each nanowire has three sharp corners fabricated by a sidewall spacer formation technique to obtain high local electrical fields. Owing to the higher carrier concentration in the channel and the high local electrical field from the three sharp corners, such a JL SONOS memory device exhibits a significantly enhanced P/E speed, a larger memory window, and better data retention properties than a conventional inversion mode NW-channel memory device.

  12. Adjustable optical response of amorphous silicon nanowires integrated with thin films.

    Science.gov (United States)

    Dhindsa, Navneet; Walia, Jaspreet; Pathirane, Minoli; Khodadad, Iman; Wong, William S; Saini, Simarjeet Singh

    2016-04-01

    We experimentally demonstrate a new optical platform by integrating hydrogenated amorphous silicon nanowire arrays with thin films deposited on transparent substrates like glass. A 535 nm thick thin film is anisotropically etched to fabricate vertical nanowire arrays of 100 nm diameter arranged in a square lattice. Adjusting the nanowire length, and consequently the thin film thickness permits the optical properties of this configuration to be tuned for either transmission filter response or enhanced broadband absorption. Vivid structural colors are also achieved in reflection and transmission. The optical properties of the platform are investigated for three different etch depths. Transmission filter response is achieved for a configuration with nanowires on glass without any thin film. Alternatively, integrating thin film with nanowires increases the absorption efficiency by ∼97% compared to the thin film starting layer and by ∼78% over nanowires on glass. The ability to tune the optical response of this material in this fashion makes it a promising platform for high performance photovoltaics, photodetectors and sensors. PMID:26906427

  13. Effect of diborane on the microstructure of boron-doped silicon nanowires

    Science.gov (United States)

    Pan, Ling; Lew, Kok-Keong; Redwing, Joan M.; Dickey, Elizabeth C.

    2005-04-01

    Boron-doped silicon (Si) nanowires, with nominal diameters of 80 nm, were grown via the vapor-liquid-solid (VLS) mechanism using gold (Au) as a catalyst and silane (SiH 4) and diborane (B 2H 6) as precursors. The microstructure of the nanowires was studied by scanning electron microscopy, transmission electron microscopy and electron energy-loss spectroscopy. At lower B 2H 6 partial pressure and thus lower doping levels (⩽1×10 18 cm -3), most of the boron-doped Si nanowires exhibited high crystallinity. At higher B 2H 6 partial pressure (˜2×10 19 cm -3 doping level), the majority of the wires exhibited a core-shell structure with an amorphous Si shell (20-30 nm thick) surrounding a crystalline Si core. Au nanoparticles on the outer surface of the nanowires were also observed in structures grown with high B/Si gas ratios. The structural changes are believed to result from an increase in the rate of Si thin-film deposition on the outer surface of the nanowire at high B 2H 6 partial pressure, which produces the amorphous coating and also causes an instability at the liquid/solid interface resulting in a loss of Au during nanowire growth.

  14. Simulation Analysis on Photoelectric Conversion Characteristics of Silicon Nanowire Array Photoelectrodes

    Science.gov (United States)

    Zhao, Yong; Yu, Jin; Fang, Li-Guang; Zheng, Jun; Wang, Hui-Qin; Yuan, Ji-Ren; Wu, Shaolong; Cheng, Guo-An

    2015-06-01

    Semiconductor nanowire photoelectrochemical cells have attracted extensive attention in the light-conversion field owing to the low-cost preparation, excellent optical absorption, and short distance of carrier collection. Although there are numbers of experimental investigations to improve the device performance, the understanding of the detailed process of photoelectric conversion needs to be further improved. In this work, a thorough optoelectronic simulation is employed to figure out how the nanowire diameter, doping concentration, and illumination wavelength affect the photoelectric conversion characteristics of the silicon nanowire array photoelectrodes. We find that two balances should be carefully weighted between optical absorption and photogenerated-carrier collection, along with between short-circuit photocurrent density and open-circuit voltage. For the small-diameter nanowire array photoelectrodes, the overall absorption is higher than that of the larger-diameter ones with the most contribution from the nanowires. However, the substrate shows increasing absorption with increasing illumination wavelength. Higher doping density leads to a larger open-circuit voltage; while lower doping density can guarantee a relatively higher short-circuit photocurrent. To obtain high-light-conversion-efficiency photoelectrodes, the doping density should be carefully chosen with considerations of illumination wavelength and surface recombination. Suppressing the surface recombination velocity can effectively enhance the short-circuit photocurrent (open-circuit voltage) for the lightly (heavily) doped nanowire array photoelectrodes. Our systematical results provide a theoretical guidance for the photoelectrochemical devices based on semiconductor nanostructures.

  15. Structural and electrochemical study of the reaction of lithium with silicon nanowires

    KAUST Repository

    Chan, Candace K.

    2009-04-01

    The structural transformations of silicon nanowires when cycled against lithium were evaluated using electrochemical potential spectroscopy and galvanostatic cycling. During the charge, the nanowires alloy with lithium to form an amorphous LixSi compound. At potentials <50 mV, a structural transformation occurs. In studies on micron-sized particles previously reported in the literature, this transformation is a crystallization to a metastable Li15Si4 phase. X-ray diffraction measurements on the Si nanowires, however, show that they are amorphous, suggesting that a different amorphous phase (LiySi) is formed. Lithium is removed from this phase in the discharge to form amorphous silicon. We have found that limiting the voltage in the charge to 70 mV results in improved efficiency and cyclability compared to charging to 10 mV. This improvement is due to the suppression of the transformation at low potentials, which alloys for reversible cycling of amorphous silicon nanowires. © 2008 Elsevier B.V. All rights reserved.

  16. CMOS-Compatible Silicon-Nanowire-Based Coulter Counter for Cell Enumeration.

    Science.gov (United States)

    Chen, Yu; Guo, Jinhong; Muhammad, Hamidullah; Kang, Yuejun; Ary, Sunil K

    2016-02-01

    A silicon-nanowire-based Coulter counter has been designed and fabricated for particle/cell enumeration. The silicon nanowire was fabricated in a fully complementary metal-oxide-semiconductor (CMOS)-compatible process and used as a field effect transistor (FET) device. The Coulter counter device worked on the principle of potential change detection introduced by the passing of microparticles/cells through a sensing channel. Device uniformity was confirmed by scanning electron microscopy and transmission electron microscopy. Current-voltage measurement showed the high sensitivity of the nanowire FET device to the surface potential change. The results revealed that the silicon-nanowire-based Coulter counter can differentiate polystyrene beads with diameters of 8 and 15 μm. Michigan Cancer Foundation-7 (MCF-7) cells have been successfully counted to validate the device. A fully CMOS-compatible fabrication process can help the device integration and facilitate the development of sensor arrays for high throughput application. With appropriate sample preparation steps, it is also possible to expand the work to applications such as rare-cells detection. PMID:26799578

  17. The Characteristics of Seebeck Coefficient in Silicon Nanowires Manufactured by CMOS Compatible Process

    Directory of Open Access Journals (Sweden)

    Choi Sung-Jin

    2010-01-01

    Full Text Available Abstract Silicon nanowires are patterned down to 30 nm using complementary metal-oxide-semiconductor (CMOS compatible process. The electrical conductivities of n-/p-leg nanowires are extracted with the variation of width. Using this structure, Seebeck coefficients are measured. The obtained maximum Seebeck coefficient values are 122 μV/K for p-leg and −94 μV/K for n-leg. The maximum attainable power factor is 0.74 mW/m K2 at room temperature.

  18. Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection

    Directory of Open Access Journals (Sweden)

    P. Pignalosa

    2011-09-01

    Full Text Available Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm and wide angle (from normal incidence to 60º antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

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

    International Nuclear Information System (INIS)

    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 LiFePO4 cathode to fabricate a lithium-ion battery cell and the cell performance evaluated by galvanostatic charge/discharge cycles

  20. Growth and properties of In(Ga)As nanowires on silicon

    International Nuclear Information System (INIS)

    In this thesis the integration of III-V semiconductor nanowires on silicon (Si) platform by molecular beam epitaxy (MBE) is investigated. All nanowires are grown without the use of foreign catalysts such as Au to achieve high purity material. First, InAs nanowires are grown in a self-assembled manner on SiOx-masked Si(111) where pinholes in the silicon oxide serve as nucleation spots for the nanowires. This leads to the growth of vertically aligned, (111)-oriented nanowires with hexagonal cross-section. Based on this simple process, the entire growth parameter window is investigated for InAs nanowires, revealing an extremely large growth temperature range from 380 C to 580 C and growth rates as large as 6 μ/h. Complex quantitative in-situ line-of-sight quadrupole mass spectrometry experiments during nanowire growth and post-growth thermal decomposition studies support these findings and indicate a very high thermal stability up to >540 C for InAs nanowires. Furthermore, the influence of the As/In ratio on the nanowire growth is studied revealing two distinct growth regimes, i.e., an In-rich regime for lower As fluxes and an As-rich regime for larger As fluxes, where the latter shows characteristic saturation of the nanowire aspect ratio. For the catalyst-free growth, detailed investigation of the growth mechanism is performed via a combination of in-situ reflection high-energy electron diffraction (RHEED) and ex-situ scanning and transmission electron microscopy (SEM,TEM). An abrupt onset of nanowire growth is observed in RHEED intensity and in-plane lattice parameter evolution. Furthermore, completely droplet-free nanowires, continuous radial growth, constant vertical growth rate and growth interruption experiments suggest a vapor-solid growth mode for all investigated nanowire samples. Moreover, site-selective (positioned) growth of InAs nanowires on pre-patterned SiO2 masked Si(111) substrates is demonstrated which is needed for ultimate control of nanowire

  1. Wavelength Conversion with Large Signal-Idler Separation using Discrete Four-Wave Mixing in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Hu, Hao; Peucheret, Christophe; Pu, Minhao;

    2012-01-01

    We have demonstrated wavelength conversion over 468 nm based on discrete bands phase matching in a silicon nanowire. CW light is converted from 1258 nm to 1726 nm with a CW pump at 1455 nm.......We have demonstrated wavelength conversion over 468 nm based on discrete bands phase matching in a silicon nanowire. CW light is converted from 1258 nm to 1726 nm with a CW pump at 1455 nm....

  2. Dynamic characterization of silicon nanowires using a terahertz optical asymmetric demultiplexer-based pump-probe scheme

    DEFF Research Database (Denmark)

    Ji, Hua; Cleary, C. S.; Dailey, J. M.;

    2012-01-01

    Dynamic phase and amplitude all-optical responses of silicon nanowires are characterized using a terahertz optical asymmetric demultiplexer (TOAD) based pump-probe scheme. Ultra-fast recovery is observed for moderate pump powers.......Dynamic phase and amplitude all-optical responses of silicon nanowires are characterized using a terahertz optical asymmetric demultiplexer (TOAD) based pump-probe scheme. Ultra-fast recovery is observed for moderate pump powers....

  3. Tailoring thermal conductivity of silicon/germanium nanowires utilizing core-shell architecture

    Science.gov (United States)

    Sarikurt, S.; Ozden, A.; Kandemir, A.; Sevik, C.; Kinaci, A.; Haskins, J. B.; Cagin, T.

    2016-04-01

    Low-dimensional nanostructured materials show large variations in their thermal transport properties. In this work, we investigate the influence of the core-shell architecture on nanowire (1D) thermal conductivity and evaluate its validity as a strategy to achieve a better thermoelectric performance. To obtain the thermal conductivity values, equilibrium molecular dynamics simulations are conducted for core-shell nanowires of silicon and germanium. To explore the parameter space, we have calculated thermal conductivity values of the Si-core/Ge-shell and Ge-core/Si-shell nanowires having different cross-sectional sizes and core contents at several temperatures. Our results indicate that (1) increasing the cross-sectional area of pristine Si and pristine Ge nanowires increases the thermal conductivity, (2) increasing the Ge core size in the Ge-core/Si-shell structure results in a decrease in the thermal conductivity at 300 K, (3) the thermal conductivity of the Si-core/Ge-shell nanowires demonstrates a minima at a specific core size, (4) no significant variation in the thermal conductivity is observed in nanowires for temperatures larger than 300 K, and (5) the predicted thermal conductivity within the frame of applied geometrical constraints is found to be around 10 W/(mK) for the Si and Ge core-shell architecture with a smooth interface. The value is still higher than the amorphous limit (1 W/(mK)). This represents a significant reduction in thermal conductivity with respect to their bulk crystalline and pristine nanowire forms. Furthermore, we observed additional suppression of thermal conductivity through the introduction of interface roughness to Si/Ge core-shell nanowires.

  4. Absorption enhancement in silicon nanowire-optical nanoantenna system for photovoltaic applications

    Science.gov (United States)

    Robak, Elżbieta; Grześkiewicz, Bartłomiej; Kotkowiak, Michał

    2014-11-01

    The rapidly growing green energy sector has prompted the search for new solutions to increase the performance of solar cells. In this area there is still room for the silicon-based photovoltaic, although the main problem is to find a way to increase the efficiency of the silicon solar cells, at the lowest possible cost. In this work we investigate the influence of a gold bowtie nanoantenna on the absorption profile of silicon nanowire. Because of the energy band gap and low effective absorption cross section, bulk silicon absorbs rather poorly in longer wavelengths of visible light and near-infrared range. Our calculations with frequency domain solver show the absorption boost in nanowire at long-wavelengths due to the coupling of the large local near-field of metallic bowtie nanoantenna to the semiconductor layer. The enhancement was observed at various levels although it was correlated with the shift of localized surface plasmon resonance thus making it dependent on the bowtie geometry. The results suggest that by incorporating metallic nanostructures as well as nanoparticles to the nanowire system, the performance of photovoltaic device can be improved thanks to greater generation of a electron-hole pairs.

  5. Enhanced photocatalytic degradation of methylene blue by metal-modified silicon nanowires

    International Nuclear Information System (INIS)

    Highlights: • SiNWs modified with Pd, Au and Pt were used as photocatalysts to degrade MB. • Yield of photodegardation increases with UV irradiation time. • SiNWs modified with Pd nanoparticles show the best photocatalytic activity. • A degradation of 97% was obtained after 200 min of UV irradiation. - Abstract: Silicon nanowires (SiNWs) modified with Au, Pt and Pd nanoparticles were used as heterogeneous photocatalysts for the photodegradation of methylene blue in water under UV light irradiation. The modification of SiNWs was carried out by deposition of metal nanoparticles using the electroless metal deposition (EMD) technique. The effect of metal nanoparticles deposition time on the photocatalytic activity was studied. It was found that the photocatalytic activity of modified SiNWs was enhanced when the deposition time of metal nanoparticles was increased. In addition of modified SiNWs with Pt, Au and Pd nanoparticles, oxidized silicon substrate (Ox-Si), oxidized silicon nanowires (Ox-SiNWs) and hydrogen-terminated silicon nanowires (H-SiNWs) were also evaluated for the photodegradation of methylene blue

  6. Enhanced photocatalytic degradation of methylene blue by metal-modified silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Brahiti, N., E-mail: dihiabrahiti@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique (CRTSE), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 Merveilles, Alger (Algeria); Université Mouloud MAMMERI de TiziOuzou, Département de Physique, Bastos (Algeria); Hadjersi, T., E-mail: hadjersi@gmx.com [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique (CRTSE), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 Merveilles, Alger (Algeria); Menari, H. [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique (CRTSE), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 Merveilles, Alger (Algeria); Amirouche, S.; El Kechai, O. [Université Mouloud MAMMERI de TiziOuzou, Département de Physique, Bastos (Algeria)

    2015-02-15

    Highlights: • SiNWs modified with Pd, Au and Pt were used as photocatalysts to degrade MB. • Yield of photodegardation increases with UV irradiation time. • SiNWs modified with Pd nanoparticles show the best photocatalytic activity. • A degradation of 97% was obtained after 200 min of UV irradiation. - Abstract: Silicon nanowires (SiNWs) modified with Au, Pt and Pd nanoparticles were used as heterogeneous photocatalysts for the photodegradation of methylene blue in water under UV light irradiation. The modification of SiNWs was carried out by deposition of metal nanoparticles using the electroless metal deposition (EMD) technique. The effect of metal nanoparticles deposition time on the photocatalytic activity was studied. It was found that the photocatalytic activity of modified SiNWs was enhanced when the deposition time of metal nanoparticles was increased. In addition of modified SiNWs with Pt, Au and Pd nanoparticles, oxidized silicon substrate (Ox-Si), oxidized silicon nanowires (Ox-SiNWs) and hydrogen-terminated silicon nanowires (H-SiNWs) were also evaluated for the photodegradation of methylene blue.

  7. Resonant tunnelling features in a suspended silicon nanowire single-hole transistor

    Energy Technology Data Exchange (ETDEWEB)

    Llobet, Jordi; Pérez-Murano, Francesc, E-mail: francesc.perez@csic.es, E-mail: z.durrani@imperial.ac.uk [Institut de Microelectrònica de Barcelona (IMB-CNM CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Krali, Emiljana; Wang, Chen; Jones, Mervyn E.; Durrani, Zahid A. K., E-mail: francesc.perez@csic.es, E-mail: z.durrani@imperial.ac.uk [Department of Electrical and Electronic Engineering, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Arbiol, Jordi [Institució Catalana de Recerca i Estudis Avançats (ICREA) and Institut Català de Nanociència i Nanotecnologia (ICN2), Campus UAB, 08193 Bellaterra, Catalonia (Spain); CELLS-ALBA Synchrotron Light Facility, 08290 Cerdanyola, Catalonia (Spain)

    2015-11-30

    Suspended silicon nanowires have significant potential for a broad spectrum of device applications. A suspended p-type Si nanowire incorporating Si nanocrystal quantum dots has been used to form a single-hole transistor. Transistor fabrication uses a novel and rapid process, based on focused gallium ion beam exposure and anisotropic wet etching, generating <10 nm nanocrystals inside suspended Si nanowires. Electrical characteristics at 10 K show Coulomb diamonds with charging energy ∼27 meV, associated with a single dominant nanocrystal. Resonant tunnelling features with energy spacing ∼10 meV are observed, parallel to both diamond edges. These may be associated either with excited states or hole–acoustic phonon interactions, in the nanocrystal. In the latter case, the energy spacing corresponds well with reported Raman spectroscopy results and phonon spectra calculations.

  8. Fabrication and evaluation of series-triple quantum dots by thermal oxidation of silicon nanowire

    International Nuclear Information System (INIS)

    Series-connected triple quantum dots were fabricated by a simple two-step oxidation technique using the pattern-dependent oxidation of a silicon nanowire and an additional oxidation of the nanowire through the gap of the fine gates attached to the nanowire. The characteristics of multi-dot single-electron devices are obtained. The formation of each quantum dot beneath an attached gate is confirmed by analyzing the electrical characteristics and by evaluating the gate capacitances between all pairings of gates and quantum dots. Because the gate electrode is automatically attached to each dot, the device structure benefits from scalability. This technique promises integrability of multiple quantum dots with individual control gates

  9. Resonant tunnelling features in a suspended silicon nanowire single-hole transistor

    International Nuclear Information System (INIS)

    Suspended silicon nanowires have significant potential for a broad spectrum of device applications. A suspended p-type Si nanowire incorporating Si nanocrystal quantum dots has been used to form a single-hole transistor. Transistor fabrication uses a novel and rapid process, based on focused gallium ion beam exposure and anisotropic wet etching, generating <10 nm nanocrystals inside suspended Si nanowires. Electrical characteristics at 10 K show Coulomb diamonds with charging energy ∼27 meV, associated with a single dominant nanocrystal. Resonant tunnelling features with energy spacing ∼10 meV are observed, parallel to both diamond edges. These may be associated either with excited states or hole–acoustic phonon interactions, in the nanocrystal. In the latter case, the energy spacing corresponds well with reported Raman spectroscopy results and phonon spectra calculations

  10. Fabrication and evaluation of series-triple quantum dots by thermal oxidation of silicon nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Takafumi, E-mail: takafumi-uchida@frontier.hokudai.ac.jp; Jo, Mingyu; Tsurumaki-Fukuchi, Atsushi; Arita, Masashi; Takahashi, Yasuo [Graduate School of Information Science and Technology, Hokkaido University, Sapporo, 060-0814 Japan (Japan); Fujiwara, Akira [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, 243-0198 Japan (Japan)

    2015-11-15

    Series-connected triple quantum dots were fabricated by a simple two-step oxidation technique using the pattern-dependent oxidation of a silicon nanowire and an additional oxidation of the nanowire through the gap of the fine gates attached to the nanowire. The characteristics of multi-dot single-electron devices are obtained. The formation of each quantum dot beneath an attached gate is confirmed by analyzing the electrical characteristics and by evaluating the gate capacitances between all pairings of gates and quantum dots. Because the gate electrode is automatically attached to each dot, the device structure benefits from scalability. This technique promises integrability of multiple quantum dots with individual control gates.

  11. Large initial compressive stress in top-down fabricated silicon nanowires evidenced by static buckling

    International Nuclear Information System (INIS)

    Single crystal silicon nanowires with a width down to 25 nm and a length-to-width (L/w) aspect ratio up to 177 were fabricated by surface micromachining of thin SOI wafers. It is demonstrated that these top-down fabricated clamped-clamped nanowires are laterally buckled when L/w is larger than about 44. This is attributed to an unexpected high compressive residual pre-stress estimated to be in the −270 to −335 MPa range from a simple nonlinear post-buckling model. The origin of this stress is investigated by considering several axial stress generation mechanisms in the silicon nanowires such as thermomechanical stresses, surface layers and deformation stresses of dies induced by patterning or die attachment. It is shown that none of these mechanisms can generate the observed initial compressive stress and high temperature steps during SOI wafers fabrication and/or thinning are likely to be the main cause of high compressive stress generation. Possible occurrence of a large stress in top-down fabricated Si nanowires is often ignored and must be considered in future works notably for electrical and thermal transport investigations. (paper)

  12. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    International Nuclear Information System (INIS)

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

  13. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    Energy Technology Data Exchange (ETDEWEB)

    He Ying, E-mail: yinghe@staff.shu.edu.c [Shanghai University, Department of Polymer Materials, School of Materials Science and Engineering (China); Wang Junan [Shanghai University, Institute of Materials, School of Materials Science and Engineering (China); Pei Changlong; Song Jizhong; Zhu Di; Chen Jie [Shanghai University, Department of Polymer Materials, School of Materials Science and Engineering (China)

    2010-10-15

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    1. INTRODUCTION Self-assembled diphenylalanine peptide nanotubes provide a means of achieving nanostructured materials in a very simple and fast way. Recent discoveries have shown that this unique material, in addition to remaining stable under dry conditions, rapidly dissolves in water making it a...... photolithography, and after deposition of the electrodes, self-assembled peptide nanotubes (PNT), figure 1, were positioned on top of the electrodes. The silicon nanowires were then etched in a reactive ion etching process masked by the positioned peptide nanotubes. Finally, the peptide nanotubes were dissolved by...... placing the now processed wafers in a distilled water bath. Figure 2 shows a SEM image of a PNT positioned between two metal electrodes. The silicon nanowire fabricated in this experiment had a width on the order of 250 nm – well below the limitations of standard photolithography, figure 3. To verify if...

  15. The Development of High-Density Vertical Silicon Nanowires and Their Application in a Heterojunction Diode

    Directory of Open Access Journals (Sweden)

    Wen-Chung Chang

    2016-06-01

    Full Text Available Vertically aligned p-type silicon nanowire (SiNW arrays were fabricated through metal-assisted chemical etching (MACE of Si wafers. An indium tin oxide/indium zinc oxide/silicon nanowire (ITO/IZO/SiNW heterojunction diode was formed by depositing ITO and IZO thin films on the vertically aligned SiNW arrays. The structural and electrical properties of the resulting ITO/IZO/SiNW heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM, X-ray diffraction (XRD, and current−voltage (I−V measurements. Nonlinear and rectifying I−V properties confirmed that a heterojunction diode was successfully formed in the ITO/IZO/SiNW structure. The diode had a well-defined rectifying behavior, with a rectification ratio of 550.7 at 3 V and a turn-on voltage of 2.53 V under dark conditions.

  16. Room temperature NO2 gas sensing of Au-loaded tungsten oxide nanowires/porous silicon hybrid structure

    Science.gov (United States)

    Deng-Feng, Wang; Ji-Ran, Liang; Chang-Qing, Li; Wen-Jun, Yan; Ming, Hu

    2016-02-01

    In this work, we report an enhanced nitrogen dioxide (NO2) gas sensor based on tungsten oxide (WO3) nanowires/porous silicon (PS) decorated with gold (Au) nanoparticles. Au-loaded WO3 nanowires with diameters of 10 nm-25 nm and lengths of 300 nm-500 nm are fabricated by the sputtering method on a porous silicon substrate. The high-resolution transmission electron microscopy (HRTEM) micrographs show that Au nanoparticles are uniformly distributed on the surfaces of WO3 nanowires. The effect of the Au nanoparticles on the NO2-sensing performance of WO3 nanowires/porous silicon is investigated over a low concentration range of 0.2 ppm-5 ppm of NO2 at room temperature (25 °C). It is found that the 10-Å Au-loaded WO3 nanowires/porous silicon-based sensor possesses the highest gas response characteristic. The underlying mechanism of the enhanced sensing properties of the Au-loaded WO3 nanowires/porous silicon is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274074 and 61271070) and the Key Research Program of Application Foundation and Advanced Technology of Tianjin, China (Grant No. 11JCZDJC15300).

  17. Organic Bioelectronic Tools for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Susanne Löffler

    2015-11-01

    Full Text Available Organic bioelectronics forms the basis of conductive polymer tools with great potential for application in biomedical science and medicine. It is a rapidly growing field of both academic and industrial interest since conductive polymers bridge the gap between electronics and biology by being electronically and ionically conductive. This feature can be employed in numerous ways by choosing the right polyelectrolyte system and tuning its properties towards the intended application. This review highlights how active organic bioelectronic surfaces can be used to control cell attachment and release as well as to trigger cell signaling by means of electrical, chemical or mechanical actuation. Furthermore, we report on the unique properties of conductive polymers that make them outstanding materials for labeled or label-free biosensors. Techniques for electronically controlled ion transport in organic bioelectronic devices are introduced, and examples are provided to illustrate their use in self-regulated medical devices. Organic bioelectronics have great potential to become a primary platform in future bioelectronics. We therefore introduce current applications that will aid in the development of advanced in vitro systems for biomedical science and of automated systems for applications in neuroscience, cell biology and infection biology. Considering this broad spectrum of applications, organic bioelectronics could lead to timely detection of disease, and facilitate the use of remote and personalized medicine. As such, organic bioelectronics might contribute to efficient healthcare and reduced hospitalization times for patients.

  18. Improved performance of silicon nanowire/cadmium telluride quantum dots/organic hybrid solar cells

    International Nuclear Information System (INIS)

    Highlights: • We introduce an intermediate cadmium telluride quantum dots (CdTe QDs) layer between the organic with silicon nanowires of hybrid solar cells as a down-shifting layer. • The hybrid solar cell got the maximum short circuit current density of 33.5 mA/cm2, getting an increase of 15.1% comparing to solar cell without CdTe QDs. • The PCE of the hybrid solar cells with CdTe QDs layer increases 28.8%. - Abstract: We fabricated silicon nanowire/cadmium telluride quantum dots (CdTe QDs)/organic hybrid solar cells and investigated their structure and electrical properties. Transmission electron microscope revealed that CdTe QDs were uniformly distributed on the surface of the silicon nanowires, which made PEDOT:PSS easily filled the space between SiNWs. The current density–voltage (J–V) characteristics of hybrid solar cells were investigated both in dark and under illumination. The result shows that the performance of the hybrid solar cells with CdTe QDs layer has an obvious improvement. The optimal short-circuit current density (Jsc) of solar cells with CdTe QDs layer can reach 33.5 mA/cm2. Compared with the solar cells without CdTe QDs, Jsc has an increase of 15.1%. Power conversion efficiency of solar cells also increases by 28.8%. The enhanced performance of the hybrid solar cells with CdTe QDs layers are ascribed to down-shifting effect of CdTe QDs and the modification of the silicon nanowires surface with CdTe QDs. The result of our experiments suggests that hybrid solar cells with CdTe QDs modified are promising candidates for solar cell application

  19. Tunable narrowband microwave photonic filter created by stimulated Brillouin scattering from a Silicon nanowire

    OpenAIRE

    Casas-Bedoya, Alvaro; Morrison, Blair; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J.

    2015-01-01

    We demonstrate the first functional signal processing device based on stimulated Brillouin scattering in a silicon nanowire. We use only 1 dB of on-chip SBS gain to create an RF photonic notch filter with 48 dB of suppression, 98 MHz linewidth, and 6 GHz frequency tuning. This device has potential applications in on-chip microwave signal processing and establishes the foundation for the first CMOS-compatible high performance RF photonic filter.

  20. Tunable narrowband microwave photonic filter created by stimulated Brillouin scattering from a silicon nanowire

    Science.gov (United States)

    Casas-Bedoya, Alvaro; Morrison, Blair; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J.

    2015-09-01

    We demonstrate the first functional signal processing device based on stimulated Brillouin scattering in a silicon nanowire. We use only 1 dB of on-chip SBS gain to create an RF photonic notch filter with 48 dB of suppression, 98 MHz linewidth, and 6 GHz frequency tuning. This device has potential applications in on-chip microwave signal processing and establishes the foundation for the first CMOS-compatible high performance RF photonic filter.

  1. Potential barrier height at the grain boundaries of a poly-silicon nanowire.

    Science.gov (United States)

    Shamir, Assaf; Amit, Iddo; Englander, Danny; Horvitz, Dror; Rosenwaks, Yossi

    2015-09-01

    We present measurements of the potential barrier height and its dependence on grain size in poly-silicon nanowire (P-SiNW) arrays. Measurements conducted using Kelvin probe force microscopy coupled with electrostatic simulations, enabled us also to extract the density of the grain boundary interface states and their energy distribution. In addition it was shown that the barrier height scales with the grain size as the square of the grain radius. PMID:26245190

  2. High Kerr nonlinearity hydrogenated amorphous silicon nanowires with low two photon absorption and high optical stability

    CERN Document Server

    Grillet, C; Monat, C; Grosse, P; Bakir, B Ben; Menezo, S; Fedeli, J M; Moss, David J

    2014-01-01

    We demonstrate optically stable amorphous silicon nanowires with both high nonlinear figure of merit (FOM) of ~5 and high nonlinearity Re({\\gamma}) = 1200W-1m-1. We observe no degradation in these parameters over the entire course of our experiments including systematic study under operation at 2 W coupled peak power (i.e. ~2GW/cm2) over timescales of at least an hour.

  3. Stable, highly nonlinear amorphous silicon nanowires with very low nonlinear absorption

    CERN Document Server

    Carletti, Luca; Grossec, Phillipe; Ben-Bakir, Badhise; Menezoc, Sylvie; Fedelic, Jean-Marc; Moss, David J; Monat, Christelle

    2014-01-01

    The nonlinear characteristics of hydrogenated amorphous silicon nanowires are experimentally demonstrated. A high nonlinear refractive index, n2=1.19 x 10-17 m2/W, combined with a low two-photon absorption, 0.14 x 10-11 m/W, resulted in a high nonlinear FOM of 5.5. Furthermore, systematic studies over hours of operational time under 2.2W of pulse peak power revealed no degradation of the optical response.

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

    OpenAIRE

    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. W...

  5. Critical Role of Diels–Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer

    Science.gov (United States)

    Heo, Gaeun; Pyo, Kyoung-hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-01-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels–Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching–releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11. PMID:27140436

  6. Critical Role of Diels–Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer

    Science.gov (United States)

    Heo, Gaeun; Pyo, Kyoung-Hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-05-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels–Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching–releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11.

  7. Thermal Conductivity Suppression in Nanostructured Silicon and Germanium Nanowires

    Science.gov (United States)

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

    2016-03-01

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

  8. Large scale low cost fabrication of diameter controllable silicon nanowire arrays

    International Nuclear Information System (INIS)

    We report on a novel solution etching method to fabricate vertically aligned aperiodic silicon nanowire (SiNW) arrays. We begin with a simple dewetting process to fabricate a monolayer of well-spaced metal particles in situ on a silicon wafer. The particles function as a sacrificial template to pattern a Ti/Au catalyst film into a metal mesh and the size of particles directly determines the diameter of SiNW. A conventional metal-assisted chemical etching process is then carried out with the obtained metal mesh as a catalyst to realize a vertically aligned SiNW array at a large scale and low cost. (papers)

  9. Hydrogen-terminated silicon nanowire photocatalysis: Benzene oxidation and methyl red decomposition

    International Nuclear Information System (INIS)

    Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: ► Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. ► Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. ► The Si/SiOx core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC–MS and UV–Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 × 10−4 M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

  10. Ultra-low reflection porous silicon nanowires for solar cell applications

    KAUST Repository

    Najar, Adel

    2012-01-01

    High density vertically aligned Porous Silicon NanoWires (PSiNWs) were fabricated on silicon substrate using metal assisted chemical etching process. A linear dependency of nanowire length to the etching time was obtained and the change in the growth rate of PSiNWs by increasing etching durations was shown. A typical 2D bright-field TEM image used for volume reconstruction of the sample shows the pores size varying from 10 to 50 nm. Furthermore, reflectivity measurements show that the 35% reflectivity of the starting silicon wafer drops to 0.1% recorded for more than 10 μm long PSiNWs. Models based on cone shape of nanowires located in a circular and rectangular bases were used to calculate the reflectance employing the Transfert Matrix Formalism (TMF) of the PSiNWs layer. Using TMF, the Bruggeman model was used to calculate the refractive index of PSiNWs layer. The calculated reflectance using circular cone shape fits better the measured reflectance for PSiNWs. The remarkable decrease in optical reflectivity indicates that PSiNWs is a good antireflective layer and have a great potential to be utilized in radial or coaxial p-n heterojunction solar cells that could provide orthogonal photon absorption and enhanced carrier collection. ©2012 Optical Society of America.

  11. Probing ultrafast carrier dynamics, nonlinear absorption and refraction in core–shell silicon nanowires

    Indian Academy of Sciences (India)

    Sunil Kumar; M Khorasaninejad; M M Adachi; K S Karim; S S Saini; A K Sood

    2012-09-01

    We investigate the relaxation dynamics of photogenerated carriers in silicon nanowires consisting of a crystalline core and a surrounding amorphous shell, using femtosecond time resolved differential reflectivity and transmission spectroscopy at 3.15 eV and 1.57 eV photon energies. The complex behaviour of the differential transmission and reflectivity transients is the mixed contributions from the crystalline core and the amorphous silicon on the nanowire surface and the substrate where competing effects of state-filling and photoinduced absorption govern the carrier dynamics. Faster relaxation rates are observed on increasing the photogenerated carrier density. Independent experimental results on crystalline silicon-on-sapphire (SOS) help us in separating the contributions from the carrier dynamics in crystalline core and the amorphous regions in the nanowire samples. Further, single-beam z-scan nonlinear transmission experiments at 1.57 eV in both open- and close-aperture configurations yield two-photon absorption coefficient (∼3 cm/GW) and nonlinear refraction coefficient (−2.5 × 10−4 cm2 /GW).

  12. Electrical detection of dengue virus (DENV) DNA oligomer using silicon nanowire biosensor with novel molecular gate control.

    Science.gov (United States)

    Nuzaihan M N, M; Hashim, U; Md Arshad, M K; Kasjoo, S R; Rahman, S F A; Ruslinda, A R; Fathil, M F M; Adzhri, R; Shahimin, M M

    2016-09-15

    In this paper, a silicon nanowire biosensor with novel molecular gate control has been demonstrated for Deoxyribonucleic acid (DNA) detection related to dengue virus (DENV). The silicon nanowire was fabricated using the top-down nanolithography approach, through nanostructuring of silicon-on-insulator (SOI) layers achieved by combination of the electron-beam lithography (EBL), plasma dry etching and size reduction processes. The surface of the fabricated silicon nanowire was functionalized by means of a three-step procedure involving surface modification, DNA immobilization and hybridization. This procedure acts as a molecular gate control to establish the electrical detection for 27-mers base targets DENV DNA oligomer. The electrical detection is based on the changes in current, resistance and conductance of the sensor due to accumulation of negative charges added by the immobilized probe DNA and hybridized target DNA. The sensitivity of the silicon nanowire biosensors attained was 45.0µAM(-1), which shows a wide-range detection capability of the sensor with respect to DNA. The limit of detection (LOD) achieved was approximately 2.0fM. The demonstrated results show that the silicon nanowire has excellent properties for detection of DENV with outstanding repeatability and reproducibility performances. PMID:27107147

  13. Localisation of silicon nanowires grown by UHV-CVD in (111)-oriented apertures opened in Si (001)

    International Nuclear Information System (INIS)

    In this paper, we have investigated an alternative method to obtain well-organized silicon nanowires grown by vapor-liquid-solid process. We have studied the influence of the droplet size on the growth direction of nanowires on plain wafers. By using self-organized Au droplets grown by molecular beam epitaxy on vicinal Si(111) surface with a 20 miscut towards the [11-2] crystallographic direction, we have obtained well organized gold droplets along the steps with small size dispersion. The growth of Si nanowires from these droplets allows defining a critical diameter for changing the Si nanowires growth direction. When the gold droplet diameter is larger than 100 nm, Si nanowires exhibit a orientation and remain free of structural defects. The localisation of Si nanowires was performed in nanoscale silicon seeds formed by modified local oxidation of silicon process. This approach, based on a simple and reliable method, enable the organisation of Si nanowires with orientation on Si(001) substrates.

  14. Thermal Test of an Improved Platform for Silicon Nanowire-Based Thermoelectric Micro-generators

    Science.gov (United States)

    Calaza, C.; Fonseca, L.; Salleras, M.; Donmez, I.; Tarancón, A.; Morata, A.; Santos, J. D.; Gadea, G.

    2016-03-01

    This work reports on an improved design intended to enhance the thermal isolation between the hot and cold parts of a silicon-based thermoelectric microgenerator. Micromachining techniques and silicon on insulator substrates are used to obtain a suspended silicon platform surrounded by a bulk silicon rim, in which arrays of bottom-up silicon nanowires are integrated later on to join both parts with a thermoelectric active material. In previous designs the platform was linked to the rim by means of bulk silicon bridges, used as mechanical support and holder for the electrical connections. Such supports severely reduce platform thermal isolation and penalise the functional area due to the need of longer supports. A new technological route is planned to obtain low thermal conductance supports, making use of a particular geometrical design and a wet bulk micromachining process to selectively remove silicon shaping a thin dielectric membrane. Thermal conductance measurements have been performed to analyse the influence of the different design parameters of the suspended platform (support type, bridge/membrane length, separation between platform and silicon rim,) on overall thermal isolation. A thermal conductance reduction from 1.82 mW/K to 1.03 mW/K, has been obtained on tested devices by changing the support type, even though its length has been halved.

  15. Electrowetting properties of atomic layer deposited Al{sub 2}O{sub 3} decorated silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Rajkumar, K.; Rajavel, K. [Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu (India); Cameron, D. C. [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); current address Miktech Oy, Mikkeli (Finland); Mangalaraj, D. [Department of NanoScience and Technology, Bharathiar University, Coimbatore, Tamil Nadu (India); Rajendrakumar, R. T., E-mail: buc@edu.in [Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu (India); Department of NanoScience and Technology, Bharathiar University, Coimbatore, Tamil Nadu (India)

    2015-06-24

    This paper reports the electrowetting properties of liquid droplet on superhydrophobic silicon nanowires with Atomic layer deposited (ALD) Al{sub 2}O{sub 3} as dielectric layer. Silicon wafer were etched by metal assisted wet chemical etching with silver as catalyst. ALD Al{sub 2}O{sub 3} films of 10nm thickness were conformally deposited over silicon nanowires. Al{sub 2}O{sub 3} dielectric film coated silicon nanowires was chemically modified with Trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane to make it superhydrophobic(SHP). The contact angle was measured and all the samples exhibited superhydrophobic nature with maximum contact angles of 163° and a minimum contact angle hysteresis of 6°. Electrowetting induced a maximum reversible decrease of the contact angle of 20°at 150V in air.

  16. Coated Silicon Nanowires as Anodes in Lithium Ion Batteries

    OpenAIRE

    Watts, David James

    2014-01-01

    Even though it has the highest known theoretical specific capacity of any material (~3600 mAh/g), silicon has limited use as an anode in lithium ion batteries due to the mechanical instability caused by the large volume expansion that occurs upon Li insertion. This volume expansion not only contributes to mechanical instability in the active silicon, but it also contributes to mechanical instability in the solid electrolyte interphase (SEI), a film formed at the end of the first lithiation s...

  17. Germanium nanowires and germanium nanoparticles embedded into hydrogenated silicon matrix

    Czech Academy of Sciences Publication Activity Database

    Stuchlíková, The-Ha; Dřínek, Vladislav; Remeš, Zdeněk; Stuchlík, Jiří

    Cairn: IPCS International Plasma Chemistry Society, 2013. (IPSC. 21). ISBN N. [International Symposium on Plasma Chemistry (ISPC 21)/21./. Cairns Convention Centre (AU), 04.08.2013-09.08.2013] R&D Projects: GA MŠk LH12236; GA ČR GA13-25747S Grant ostatní: AVČR(CZ) M100101216; AVČR(CZ) M100101217 Institutional support: RVO:68378271 ; RVO:67985858 Keywords : nanowires * quantum dots * matrix * CVD * PECVD * LA Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Gelatin coated electrodes allow prolonged bioelectronic measurements

    Science.gov (United States)

    1966-01-01

    Silver electrodes treated with an anodizing electrolyte containing gelatin are used for long term monitoring of bioelectronic potentials in humans. The electrodes do not interact with perspiration, cause skin irritation, or promote the growth of bacteria.

  19. Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method

    OpenAIRE

    Ouertani, Rachid; Hamdi, Abderrahmen; Amri, Chohdi; Khalifa, Marouan; Ezzaouia, Hatem

    2014-01-01

    In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to...

  20. Conjugated polymer–silicon nanowire array hybrid Schottky diode for solar cell application

    International Nuclear Information System (INIS)

    The hybrid Schottky diode based on silicon nanowire arrays (SiNWs) and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) has been fabricated for high performance solar cells. The length of SiNWs on a silicon substrate, which is prepared by metal-assisted chemical etching, can be tuned by adjusting the length of the etching time. In addition, the average distances between the adjacent silicon nanowires can be controlled by changing the immersing time in a saturated PCl5 solution. The hybrid devices are made from the SiNWs with different wire lengths and various distances between adjacent wires by spin-casting PEDOT:PSS on the silicon substrates. It is found that the length and density play leading roles in the electric output characteristics. The device made from SiNWs with optimum morphology can achieve a power conversion efficiency of 7.3%, which is much improved in comparison with that of the planar one. The measurement of the transient photovoltage decay and the analysis of the current versus voltage curve indicate that the charge recombination process is a dominant factor on the device performance. (paper)

  1. Fabrication of silicon nanowire arrays by macroscopic galvanic cell-driven metal catalyzed electroless etching in aerated HF solution.

    Science.gov (United States)

    Liu, Lin; Peng, Kui-Qing; Hu, Ya; Wu, Xiao-Ling; Lee, Shuit-Tong

    2014-03-01

    Macroscopic galvanic cell-driven metal catalyzed electroless etching (MCEE) of silicon in aqueous hydrofluoric acid (HF) solution is devised to fabricate silicon nanowire (SiNW) arrays with dissolved oxygen acting as the one and only oxidizing agent. The key aspect of this strategy is the use of a graphite or other noble metal electrode that is electrically coupled with silicon substrate. PMID:24323873

  2. Growth and properties of In(Ga)As nanowires on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hertenberger, Simon

    2012-10-15

    In this thesis the integration of III-V semiconductor nanowires on silicon (Si) platform by molecular beam epitaxy (MBE) is investigated. All nanowires are grown without the use of foreign catalysts such as Au to achieve high purity material. First, InAs nanowires are grown in a self-assembled manner on SiO{sub x}-masked Si(111) where pinholes in the silicon oxide serve as nucleation spots for the nanowires. This leads to the growth of vertically aligned, (111)-oriented nanowires with hexagonal cross-section. Based on this simple process, the entire growth parameter window is investigated for InAs nanowires, revealing an extremely large growth temperature range from 380 C to 580 C and growth rates as large as 6 μ/h. Complex quantitative in-situ line-of-sight quadrupole mass spectrometry experiments during nanowire growth and post-growth thermal decomposition studies support these findings and indicate a very high thermal stability up to >540 C for InAs nanowires. Furthermore, the influence of the As/In ratio on the nanowire growth is studied revealing two distinct growth regimes, i.e., an In-rich regime for lower As fluxes and an As-rich regime for larger As fluxes, where the latter shows characteristic saturation of the nanowire aspect ratio. For the catalyst-free growth, detailed investigation of the growth mechanism is performed via a combination of in-situ reflection high-energy electron diffraction (RHEED) and ex-situ scanning and transmission electron microscopy (SEM,TEM). An abrupt onset of nanowire growth is observed in RHEED intensity and in-plane lattice parameter evolution. Furthermore, completely droplet-free nanowires, continuous radial growth, constant vertical growth rate and growth interruption experiments suggest a vapor-solid growth mode for all investigated nanowire samples. Moreover, site-selective (positioned) growth of InAs nanowires on pre-patterned SiO{sub 2} masked Si(111) substrates is demonstrated which is needed for ultimate control of

  3. Microfluidic design for bio-sample delivery to silicon nanowire biosensor - a simulation study

    International Nuclear Information System (INIS)

    We examine various microfluidic channel designs for sample delivery to silicon nano-wire biosensors pertaining to the modeling and simulation. Nano-wires with its high sensitivity permits label free detection of bio-molecules. Without careful considerations to its fluidic delivery network, effects of detection can be limited. Different micro-channel designs of relatively larger width aid in fluid release and sensors are placed strategically to attain high efficiency in bio-sample delivery. One design establishes the viability of hydrodynamic focusing through splitting a single flow into two and permits focusing of bio-samples at the flow recombination region. It avoids the delicated fluidic delivery systems generally used in hydrodynamic focusing. A focusing effect of 71.3% based on the movement of a massless particle in the fluid is achieved using a straight channel design with a partition wall inside. Moreover, sample is focused in low velocity region which maintains minimal impact to nanowire sensor. This provides a simple and efficient delivery system for the nano-wire sensor upon integration

  4. Vapor-liquid-solid growth of silicon and silicon germanium nanowires

    Science.gov (United States)

    Nimmatoori, Pramod

    2009-12-01

    Si and Si1-xGex nanowires are promising materials with potential applications in various disciplines of science and technology. Small diameter nanowires can act as model systems to study interesting phenomena such as tunneling that occur in the nanometer regime. Furthermore, technical challenges in fabricating nanoscale size devices from thin films have resulted in interest and research on nanowires. In this perspective, vertical integrated nanowire field effect transistors (VINFETs) fabricated from Si nanowires are promising devices that offer better control on device properties and push the transistor architecture into the third dimension potentially enabling ultra-high transistor density circuits. Transistors fabricated from Si/Si 1-xGex nanowires have also been proposed that can have high carrier mobility. In addition, the Si and Si1-xGe x nanowires have potential to be used in various applications such as sensing, thermoelectrics and solar cells. Despite having considerable potential, the understanding of the vapor-liquid-solid (VLS) mechanism utilized to fabricate these wires is still rudimentary. Hence, the objective of this thesis is to understand the effects of nanoscale size and the role of catalyst that mediates the wire growth on the growth rate of Si and Si1-xGe x nanowires and interfacial abruptness in Si/Si1-xGe x axial heterostructure nanowires. Initially, the growth and structural properties of Si nanowires with tight diameter distribution grown from 10, 20 and 50 nm Au particles dispersed on a polymer-modified substrate was studied. A nanoparticle application process was developed to disperse Au particles on the substrate surface with negligible agglomeration and sufficient density. The growth temperature and SiH4 partial pressure were varied to optimize the growth conditions amenable to VLS growth with smooth wire morphology and negligible Si thin film deposition on wire sidewalls. The Si nanowire growth rate was studied as a function of growth

  5. Fabrication of a sub-10 nm silicon nanowire based ethanol sensor using block copolymer lithography.

    Science.gov (United States)

    Rasappa, Sozaraj; Borah, Dipu; Faulkner, Colm C; Lutz, Tarek; Shaw, Matthew T; Holmes, Justin D; Morris, Michael A

    2013-02-15

    This paper details the fabrication of ultrathin silicon nanowires (SiNWs) on a silicon-on-insulator (SOI) substrate as an electrode for the electro-oxidation and sensing of ethanol. The nanowire surfaces were prepared by a block copolymer (BCP) nanolithographic technique using low molecular weight symmetric poly(styrene)-block-poly(methyl methacrylate) (PS-b-PMMA) to create a nanopattern which was transferred to the substrate using plasma etching. The BCP orientation was controlled using a hydroxyl-terminated random polymer brush of poly(styrene)-random-poly(methyl methacrylate) (HO-PS-r-PMMA). TEM cross-sections of the resultant SiNWs indicate an anisotropic etch process with nanowires of sub-10 nm feature size. The SiNWs obtained by etching show high crystallinity and there is no evidence of defect inclusion or amorphous region production as a result of the pattern transfer process. The high density of SiNWs at the substrate surface allowed the fabrication of a sensor for cyclic voltammetric detection of ethanol. The sensor shows better sensitivity to ethanol and a faster response time compared to widely used polymer nanocomposite based sensors. PMID:23340158

  6. Electronic transport properties of silicon junctionless nanowire transistors fabricated by femtosecond laser direct writing

    Science.gov (United States)

    Liu-Hong, Ma; Wei-Hua, Han; Hao, Wang; Qi-feng, Lyu; Wang, Zhang; Xiang, Yang; Fu-Hua, Yang

    2016-06-01

    Silicon junctionless nanowire transistor (JNT) is fabricated by femtosecond laser direct writing on a heavily n-doped SOI substrate. The performances of the transistor, i.e., current drive, threshold voltage, subthreshold swing (SS), and electron mobility are evaluated. The device shows good gate control ability and low-temperature instability in a temperature range from 10 K to 300 K. The drain currents increasing by steps with the gate voltage are clearly observed from 10 K to 50 K, which is attributed to the electron transport through one-dimensional (1D) subbands formed in the nanowire. Besides, the device exhibits a better low-field electron mobility of 290 cm2·V‑1·s‑1, implying that the silicon nanowires fabricated by femtosecond laser have good electrical properties. This approach provides a potential application for nanoscale device patterning. Project supported by the National Natural Science Foundation of China (Grant Nos. 61376096, 61327813, and 61404126) and the National Basic Research Program of China (Grant No. 2010CB934104).

  7. Performance analysis of silicon nanowire transistors considering effective oxide thickness of high-k gate dielectric

    International Nuclear Information System (INIS)

    We have analyzed the effective oxide thickness (EOT) of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional SiO2 gate insulator with a material that has a much higher dielectric constant (high-k) gate, materials like Si3N4, Al2O3, Y2O3 and HfO2. We have also analyzed the channel conductance, the effect of a change in thickness, the average velocity of the charge carrier and the conductance efficiency in order to study the performance of silicon nanowire transistors in the nanometer region. The analysis was performed using the Fettoy, a numerical simulator for ballistic nanowire transistors using a simple top of the barrier (Natori) approach, which is composed of several matlab scripts. Our results show that hafnium oxide (HfO2) gate insulator material provides good thermal stability, a high recrystallization temperature and better interface qualities when compared with other gate insulator materials; also the effective oxide thickness of HfO2 is found to be 0.4 nm. (semiconductor devices)

  8. A novel dynamically configurable electrostatically doped silicon nanowire impact ionization MOS

    Science.gov (United States)

    Singh, Sangeeta; Kondekar, P. N.

    2015-12-01

    In this paper, a novel dynamically configurable, electrostatically doped silicon nanowire impact ionization MOS (E-SiNW-IMOS) based on dopant-free technology is investigated. The key attribute of the proposed device is its polarity controlled dynamic reconfigurability of charge gating mechanism from impact ionization to band-to-band tunneling. This ensures that same device can act as E-SiNW-IMOS or electrostatically doped silicon nanowire Tunnel FET (E-SiNW-TFET) depending on bias conditions. It consists of an undoped SiNW and three independent all-around-gates two polarity gates to realize n+ and p+ regions in undoped nanowire by electrostatic doping and a control gate to initiate impact ionization/tunneling. Combination of biases applied at polarity gates and control gate configures both the operating mechanism and device polarity. This enables the potential co-integration of IMOS (offering high gain and ultra steep switching behavior) and TFET (with extremely low leakage current and power-efficiency) on a single chip. A calibrated 3-D TCAD study reveals consistent static device behavior for both the devices considered. It offers a simplified fabrication process as it avoids the need of ion implantation and thermal annealing, thereby reducing thermal budget. Further, it is highly resilient towards process variations, doping control issues, voltage variations and random dopant fluctuations (RDF).

  9. Characteristics of AlN/GaN nanowire Bragg mirror grown on (001) silicon by molecular beam epitaxy

    KAUST Repository

    Heo, Junseok

    2013-10-01

    GaN nanowires containing AlN/GaN distributed Bragg reflector (DBR) heterostructures have been grown on (001) silicon substrate by molecular beam epitaxy. A peak reflectance of 70% with normal incidence at 560 nm is derived from angle resolved reflectance measurements on the as-grown nanowire DBR array. The measured peak reflectance wavelength is significantly blue-shifted from the ideal calculated value. The discrepancy is explained by investigating the reflectance of the nanoscale DBRs with a finite difference time domain technique. Ensemble nanowire microcavities with In0.3Ga 0.7N nanowires clad by AlN/GaN DBRs have also been characterized. Room temperature emission from the microcavity exhibits considerable linewidth narrowing compared to that measured for unclad In0.3Ga0.7N nanowires. The resonant emission is characterized by a peak wavelength and linewidth of 575 nm and 39 nm, respectively. © 2013 AIP Publishing LLC.

  10. Enhanced Photoelectrical Response of Hydrogenated Amorphous Silicon Single-Nanowire Solar Cells by Front-Opening Crescent Design

    OpenAIRE

    Yang, Zhenhai; Cao, Guoyang; Shang, Aixue; Lei, Dang Yuan; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-01-01

    We report an approach for substantially enhancing the light-trapping and photoconversion efficiency of hydrogenated amorphous silicon (a-Si:H) single-nanowire solar cells (SNSCs) by engineering the cross section of the nanowire from circular into a front-opening crescent shape. The proposed SNSCs show a broadband and highly tunable optical absorption compared to the conventional circular counterparts under both transverse electric and transverse magnetic incidences, enabling an enhancement ra...

  11. Electrical Control of g-Factor in a Few-Hole Silicon Nanowire MOSFET.

    Science.gov (United States)

    Voisin, B; Maurand, R; Barraud, S; Vinet, M; Jehl, X; Sanquer, M; Renard, J; De Franceschi, S

    2016-01-13

    Hole spins in silicon represent a promising yet barely explored direction for solid-state quantum computation, possibly combining long spin coherence, resulting from a reduced hyperfine interaction, and fast electrically driven qubit manipulation. Here we show that a silicon-nanowire field-effect transistor based on state-of-the-art silicon-on-insulator technology can be operated as a few-hole quantum dot. A detailed magnetotransport study of the first accessible hole reveals a g-factor with unexpectedly strong anisotropy and gate dependence. We infer that these two characteristics could enable an electrically driven g-tensor-modulation spin resonance with Rabi frequencies exceeding several hundred mega-Hertz. PMID:26599868

  12. Enhanced light trapping in periodically truncated cone silicon nanowire structure

    Science.gov (United States)

    Kai, Qiu; Yuhua, Zuo; Tianwei, Zhou; Zhi, Liu; Jun, Zheng; Chuanbo, Li; Buwen, Cheng

    2015-10-01

    Light trapping plays an important role in improving the conversion efficiency of thin-film solar cells. The good wideband light trapping is achieved using our periodically truncated cone Si nanowire (NW) structures, and their inherent mechanism is analyzed and simulated by FDTD solution software. Ordered cylinder Si NW structure with initial size of 80 nm and length of 200 nm is grown by pattern transfer and selective epitaxial growth. Truncated cone Si NW array is then obtained by thermal oxidation treatment. Its mean reflection in the range of 300-900 nm is lowered to be 5% using 140 nm long truncated cone Si NW structure, compared with that of 20% using cylinder counterparts. It indicates that periodically truncated Si cone structures trap the light efficiently to enhance the light harvesting in a wide spectral range and have the potential application in highly efficient NW solar cells. Project supported by the National Natural Science Foundation of China (Nos. 51072194, 61021003, 61036001, 61376057).

  13. One-step synthesis of lightly doped porous silicon nanowires in HF/AgNO3/H2O2 solution at room temperature

    International Nuclear Information System (INIS)

    One-step synthesis of lightly doped porous silicon nanowire arrays was achieved by etching the silicon wafer in HF/AgNO3/H2O2 solution at room temperature. The lightly doped porous silicon nanowires (pNWs) have circular nanopores on the sidewall, which can emit strong green fluorescence. The surface morphologies of these nanowires could be controlled by simply adjusting the concentration of H2O2, which influences the distribution of silver nanoparticles (Ag NPs) along the nanowire axis. A mechanism based on Ag NPs-induced lateral etching of nanowires was proposed to explain the formation of pNWs. The controllable and widely applicable synthesis of pNWs will open their potential application to nanoscale photoluminescence devices. - Graphical abstract: The one-step synthesis of porous silicon nanowire arrays is achieved by chemical etching of the lightly doped p-type Si (100) wafer at room temperature. These nanowires exhibit strong green photoluminescence. SEM, TEM, HRTEM and photoluminescence images of pNWs. The scale bars of SEM, TEM HRTEM and photoluminescence are 10 μm, 20 nm, 10 nm, and 1 μm, respectively. Highlights: ► Simple one-step synthesis of lightly doped porous silicon nanowire arrays is achieved at RT. ► Etching process and mechanism are illustrated with etching model from a novel standpoint. ► As-prepared porous silicon nanowire emits strong green fluorescence, proving unique property.

  14. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array

    Science.gov (United States)

    Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-beom; Choi, Heon-Jin

    2016-07-01

    In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes.

  15. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array.

    Science.gov (United States)

    Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-Beom; Choi, Heon-Jin

    2016-12-01

    In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes. PMID:27448026

  16. Atomistic simulations of the tensile and melting behavior of silicon nanowires

    Institute of Scientific and Technical Information of China (English)

    Jing Yuhang; Meng Qingyuan; Zhao Wei

    2009-01-01

    Molecular dynamics simulations with Stillinger-Weber potential are used to study the tensile and melting behavior of single-crystalline silicon nanowires (SiNWs). The tensile tests show that the tensile behavior of the SiNWs is strongly dependent on the simulation temperature, the strain rate, and the diameter of the nanowires.For a given diameter, the critical load significantly decreases as the temperature increases and also as the strain rate decreases. Additionally, the critical load increases as the diameter increases. Moreover, the melting tests demonstrate that both melting temperature and melting heat of the SiNWs decrease with decreasing diameter and length, due to the increase in surface energy. The melting process of SiNWs with increasing temperature is also investigated.

  17. Controllable electrical and physical breakdown of poly-crystalline silicon nanowires by thermally assisted electromigration

    Science.gov (United States)

    Park, Jun-Young; Moon, Dong-Il; Seol, Myeong-Lok; Jeon, Chang-Hoon; Jeon, Gwang-Jae; Han, Jin-Woo; Kim, Choong-Ki; Park, Sang-Jae; Lee, Hee Chul; Choi, Yang-Kyu

    2016-01-01

    The importance of poly-crystalline silicon (poly-Si) in semiconductor manufacturing is rapidly increasing due to its highly controllable conductivity and excellent, uniform deposition quality. With the continuing miniaturization of electronic components, low dimensional structures such as 1-dimensional nanowires (NWs) have attracted a great deal of attention. But such components have a much higher current density than 2- or 3- dimensional films, and high current can degrade device lifetime and lead to breakdown problems. Here, we report on the electrical and thermal characteristics of poly-Si NWs, which can also be used to control electrical and physical breakdown under high current density. This work reports a controllable catastrophic change of poly-Si NWs by thermally-assisted electromigration and underlying mechanisms. It also reports the direct and real time observation of these catastrophic changes of poly-Si nanowires for the first time, using scanning electron microscopy.

  18. Scaling theory put into practice: First-principles modeling of transport in doped silicon nanowires

    DEFF Research Database (Denmark)

    Markussen, Troels; Rurali, R.; Jauho, Antti-Pekka;

    2007-01-01

    We combine the ideas of scaling theory and universal conductance fluctuations with density-functional theory to analyze the conductance properties of doped silicon nanowires. Specifically, we study the crossover from ballistic to diffusive transport in boron or phosphorus doped Si nanowires by...... computing the mean free path, sample-averaged conductance hGi, and sample-to-sample variations stdG as a function of energy, doping density, wire length, and the radial dopant profile. Our main findings are (i) the main trends can be predicted quantitatively based on the scattering properties of single...... dopants, (ii) the sample-to-sample fluctuations depend on energy but not on doping density, thereby displaying a degree of universality, and (iii) in the diffusive regime the analytical predictions of the Dorokhov-Mello-Pereyra- Kumar theory are in good agreement with our ab initio calculations....

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

    Energy Technology Data Exchange (ETDEWEB)

    Prosini, Pier Paolo [ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Casaccia Research Centre, Via Anguillarese 301, 00123 Santa Maria di Galeria, Rome (Italy); DInESto, Drive the Innovation in Energy Storage, Via Provincie, 04012 Cisterna di Latina (Italy); Rufoloni, Alessandro; Rondino, Flaminia; Santoni, Antonino [ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Frascati Research Centre, via E. Fermi 45, 00044 Frascati (Italy)

    2015-06-23

    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{sub 4} cathode to fabricate a lithium-ion battery cell and the cell performance evaluated by galvanostatic charge/discharge cycles.

  20. Controllable electrical and physical breakdown of poly-crystalline silicon nanowires by thermally assisted electromigration.

    Science.gov (United States)

    Park, Jun-Young; Moon, Dong-Il; Seol, Myeong-Lok; Jeon, Chang-Hoon; Jeon, Gwang-Jae; Han, Jin-Woo; Kim, Choong-Ki; Park, Sang-Jae; Lee, Hee Chul; Choi, Yang-Kyu

    2016-01-01

    The importance of poly-crystalline silicon (poly-Si) in semiconductor manufacturing is rapidly increasing due to its highly controllable conductivity and excellent, uniform deposition quality. With the continuing miniaturization of electronic components, low dimensional structures such as 1-dimensional nanowires (NWs) have attracted a great deal of attention. But such components have a much higher current density than 2- or 3-dimensional films, and high current can degrade device lifetime and lead to breakdown problems. Here, we report on the electrical and thermal characteristics of poly-Si NWs, which can also be used to control electrical and physical breakdown under high current density. This work reports a controllable catastrophic change of poly-Si NWs by thermally-assisted electromigration and underlying mechanisms. It also reports the direct and real time observation of these catastrophic changes of poly-Si nanowires for the first time, using scanning electron microscopy. PMID:26782708

  1. Metal-catalyzed electroless etching and nanoimprinting silicon nanowire-based solar cells: Silicon nanowire defect reduction and efficiency enhancement by two-step H2 annealing

    Science.gov (United States)

    Jevasuwan, Wipakorn; Nakajima, Kiyomi; Sugimoto, Yoshimasa; Fukata, Naoki

    2016-06-01

    The effects of H2 annealing on material properties including defects of silicon nanowire (SiNW) surface and Si film layer for solar cell application were investigated. Single-junction solar cells consisting of n-SiNWs and chemical vapor deposition grown p-Si matrix were demonstrated using two-step H2 annealing. n-SiNWs formed by two different methods of metal-catalyzed electroless etching and nanoimprinting followed by the Bosch process were compared. Two-step H2 annealing at 900 °C for 10 min after both n-SiNW formations and subsequent p-Si matrix deposition effectively improved SiNW surface and p-Si crystallinity, resulting in higher solar cell efficiency.

  2. Optical biosensor based on a silicon nanowire ridge waveguide for lab on chip applications

    Science.gov (United States)

    Gamal, Rania; Ismail, Yehea; Swillam, Mohamed A.

    2015-04-01

    We propose a novel sensor using a silicon nanowire ridge waveguide (SNRW). This waveguide is comprised of an array of silicon nanowires on an insulator substrate that has the envelope of a ridge waveguide. The SNRW inherently maximizes the overlap between the material-under-test and the incident light wave by introducing voids to the otherwise bulk structure. When a sensing sample is injected, the voids within the SNRW adopt the refractive index of the material-under-test. Hence, the strong contribution of the material-under-test to the overall modal effective index will greatly augment the sensitivity. Additionally, the ridge structure provides a fabrication convenience as it covers the entire substrate, ensuring that the etching process would not damage the substrate. Finite-difference time-domain simulations are conducted and showed that the percentage change in the effective index due to a 1% change in the surrounding environment is more than 170 times the change perceived in an evanescent-detection based bulk silicon ridge waveguide. Moreover, the SNRW proves to be more sensitive than recent other, non-evanescent sensors. In addition, the detection limit for this structure was revealed to be as small as 10-8. A compact bimodal waveguide based on SNRW is designed and tested. It delivers high sensitivity values that offer comparable performance to similar low-index light-guiding sensing configurations; however, our proposed structure has much smaller footprints and allows high dense integration for lab-on-chip applications.

  3. Raman study of phase transformation from diamond structure to wurtzite structure in the silicon nanowires

    Science.gov (United States)

    Shukla, A. K.; Dixit, Saurabh

    2016-07-01

    Hexagonal silicon has emerged as an exciting material due to its novel vibrational and electronic properties. Synthesis of the wurtzite silicon nanowires (w-SiNWs) is studied here using metal assisted chemical etching (MACE) technique. Stress induced in the SiNWs during wet chemical etching is attributed to formation of the w-SiNWs. Presence of the w-SiNWs is revealed by first-order and second-order Raman spectra. The effect of variation of deposition time of silver (catalyst) is explicitly studied for growth of w-SiNWs. The deposition time enhances the density of SiNWs in an island of vertically aligned SiNWs. Absorption coefficient studies of the w-SiNWs are also conducted using UV–vis spectroscopy as a function of deposition time. Increase in the absorption coefficient in SiNWs is noticed with increasing deposition time. The prominent quantum confinement along with stress and porosity is shown to be mainly responsible for the transformation from diamond structure to wurtzite structure in the silicon nanowires.

  4. All-Optical Wavelength Conversion of a High-Speed RZ-OOK Signal in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Hu, Hao; Ji, Hua; Galili, Michael; Pu, Minhao; Mulvad, Hans Christian Hansen; Yvind, Kresten; Hvam, Jørn Märcher; Jeppesen, Palle; Oxenløwe, Leif Katsuo

    All-optical wavelength conversion of a 320 Gb/s line-rate RZ-OOK signal is demonstrated based on four-wave mixing in a 3.6 mm long silicon nanowire. Bit error rate measurements validate the performance within FEC limits.......All-optical wavelength conversion of a 320 Gb/s line-rate RZ-OOK signal is demonstrated based on four-wave mixing in a 3.6 mm long silicon nanowire. Bit error rate measurements validate the performance within FEC limits....

  5. Wavelength conversion of 80 Gb/s RZ-DPSK Pol-MUX signals in a silicon nanowire

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Peucheret, Christophe; Oxenløwe, Leif Katsuo;

    2014-01-01

    All-optical wavelength conversion of 80 Gb/s RZ-DPSK polarization multiplexed signals is demonstrated in a silicon nanowire using an angled-pump scheme. The quality of the converted signal is characterized through BER measurements for the first time.......All-optical wavelength conversion of 80 Gb/s RZ-DPSK polarization multiplexed signals is demonstrated in a silicon nanowire using an angled-pump scheme. The quality of the converted signal is characterized through BER measurements for the first time....

  6. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties.

    Science.gov (United States)

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-12-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer. PMID:26729219

  7. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties

    Science.gov (United States)

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-01-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.

  8. Control growth of silicon nanocolumns' epitaxy on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chong, Su Kong, E-mail: sukong1985@yahoo.com.my [University of Malaya, Low Dimensional Materials Research Centre, Department of Physics (Malaysia); Dee, Chang Fu [Universiti Kebangsaan Malaysia (UKM), Institute of Microengineering and Nanoelectronics (IMEN) (Malaysia); Yahya, Noorhana [Universiti Teknologi PETRONAS, Faculty of Science and Information Technology (Malaysia); Rahman, Saadah Abdul [University of Malaya, Low Dimensional Materials Research Centre, Department of Physics (Malaysia)

    2013-04-15

    The epitaxial growth of Si nanocolumns on Si nanowires was studied using hot-wire chemical vapor deposition. A single-crystalline and surface oxide-free Si nanowire core (core radius {approx}21 {+-} 5 nm) induced by indium crystal seed was used as a substance for the vapor phase epitaxial growth. The growth process is initiated by sidewall facets, which then nucleate upon certain thickness to form Si islands and further grow to form nanocolumns. The Si nanocolumns with diameter of 10-20 nm and aspect ratio up to 10 can be epitaxially grown on the surface of nanowires. The results showed that the radial growth rate of the Si nanocolumns remains constant with the increase of deposition time. Meanwhile, the radial growth rates are controllable by manipulating the hydrogen to silane gas flow rate ratio. The optical antireflection properties of the Si nanocolumns' decorated SiNW arrays are discussed in the text.

  9. Theory of Corner States in Silicon Nanowire Devices

    Science.gov (United States)

    Saraiva, Andre; Koiller, Belita; Gonzalez-Zalba, M. Fernando

    Nanowire-based transistors, such as FinFETs and Tri-gate FETs, form one and zero dimensional states at the corners. These corner states may be manipulated for quantum electronic applications, such as tunable quantum dot-based spin qubits. We discuss the electronic structure of the electrons bound at the corner, considering the effects due to the anisotropy of the effective mass, the splitting of valleys due to the confinement and the scattering at the interface, generalizing our results to corners of arbitrary angle. Our results indicate the optimal conditions for lifting the valley degeneracy, known to impact quantum coherence and control. We finally mention the expected impacts of this geometry on the tunnel and exchange coupling between dots at opposite corners of a wire. As and BK performed this work as part of the Brazilian National Institute for Science and Technology on Quantum Information and acknowledge support from the Brazilian agencies FAPERJ, CNPq, CAPES. MFG-Z is funded by the FP7/318397-TOLOP project.

  10. Tunable narrowband microwave photonic filter created by stimulated Brillouin scattering from a silicon nanowire.

    Science.gov (United States)

    Casas-Bedoya, Alvaro; Morrison, Blair; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J

    2015-09-01

    We demonstrate the first, to the best of our knowledge, functional signal processing device based on stimulated Brillouin scattering in a silicon nanowire. We use only 1 dB of on-chip stimulated Brillouin scattering gain to create an RF photonic notch filter with 48 dB of suppression, 98 MHz linewidth, and 6 GHz frequency tuning. This device has potential applications in on-chip microwave signal processing and establishes the foundation for the first CMOS-compatible high-performance RF photonic filter. PMID:26368735

  11. Improving the cycling stability of silicon nanowire anodes with conducting polymer coatings

    KAUST Repository

    Yao, Yan

    2012-01-01

    For silicon nanowires (Si NWs) to be used as a successful high capacity lithium-ion battery anode material, improvements in cycling stability are required. Here we show that a conductive polymer surface coating on the Si NWs improves cycling stability; coating with PEDOT causes the capacity retention after 100 charge-discharge cycles to increase from 30% to 80% over bare NWs. The improvement in cycling stability is attributed to the conductive coating maintaining the mechanical integrity of the cycled Si material, along with preserving electrical connections between NWs that would otherwise have become electrically isolated during volume changes. © 2012 The Royal Society of Chemistry.

  12. Interfering Heralded Single Photons from Two Separate Silicon Nanowires Pumped at Different Wavelengths

    Directory of Open Access Journals (Sweden)

    Xiang Zhang

    2016-08-01

    Full Text Available Practical quantum photonic applications require on-demand single photon sources. As one possible solution, active temporal and wavelength multiplexing has been proposed to build an on-demand single photon source. In this scheme, heralded single photons are generated from different pump wavelengths in many temporal modes. However, the indistinguishability of these heralded single photons has not yet been experimentally confirmed. In this work, we achieve 88% ± 8% Hong–Ou–Mandel quantum interference visibility from heralded single photons generated from two separate silicon nanowires pumped at different wavelengths. This demonstrates that active temporal and wavelength multiplexing could generate indistinguishable heralded single photons.

  13. Balanced ternary addition using a gated silicon nanowire

    Science.gov (United States)

    Mol, J. A.; van der Heijden, J.; Verduijn, J.; Klein, M.; Remacle, F.; Rogge, S.

    2011-12-01

    Ternary logic has the lowest cost of complexity, here, we demonstrate a CMOS hardware implementation of a ternary adder using a silicon metal-on-insulator single electron transistor. Gate dependent rectifying behavior of a single electron transistor (SET) results in a robust three-valued output as a function of the potential of the single electron transistor island. Mapping logical, ternary inputs to the three gates controlling the potential of the single electron transistor island allows us to perform complex, inherently ternary operations, on a single transistor.

  14. Lithium Insertion In Silicon Nanowires: An ab Initio Study

    KAUST Repository

    Zhang, Qianfan

    2010-09-08

    The ultrahigh specific lithium ion storage capacity of Si nanowires (SiNWs) has been demonstrated recently and has opened up exciting opportunities for energy storage. However, a systematic theoretical study on lithium insertion in SiNWs remains a challenge, and as a result, understanding of the fundamental interaction and microscopic dynamics during lithium insertion is still lacking. This paper focuses on the study of single Li atom insertion into SiNWs with different sizes and axis orientations by using full ab initio calculations. We show that the binding energy of interstitial Li increases as the SiNW diameter grows. The binding energies at different insertion sites, which can be classified as surface, intermediate, and core sites, are quite different. We find that surface sites are energetically the most favorable insertion positions and that intermediate sites are the most unfavorable insertion positions. Compared with the other growth directions, the [110] SiNWs with different diameters always present the highest binding energies on various insertion locations, which indicates that [110] SiNWs are more favorable by Li doping. Furthermore, we study Li diffusion inside SiNWs. The results show that the Li surface diffusion has a much higher chance to occur than the surface to core diffusion, which is consistent with the experimental observation that the Li insertion in SiNWs is layer by layer from surface to inner region. After overcoming a large barrier crossing surface-to-intermediate region, the diffusion toward center has a higher possibility to occur than the inverse process. © 2010 American Chemical Society.

  15. Membrane Protein Incorporation into Nano-Bioelectronics: An insight into Rhodopsin Controlled SiNW-FET Devices

    Science.gov (United States)

    Tunuguntla, Ramya

    that the manipulation of lipid composition can indeed control orientation of an asymmetrically charged membrane protein, proteorhodopsin, in liposomes. One-dimensional inorganic nanostructures, which have critical dimensions comparable to the sizes of biological molecules, form an excellent materials platform for building such integrated structures. Researchers already use silicon nanowire-based field effect transistors functionalized with molecular recognition sites in a diverse array of biosensors. In our group, we have been developing a platform for integration of membrane protein functionality and electronic devices using a 1-D phospholipid bilayer device architecture. In these devices, the membrane proteins reside within the lipid bilayer that covers a nanowire channel of a field-effect transistor. This lipid bilayer performs several functions: it shields the nanowire from the solution species; it serves as a native-like environment for membrane proteins and preserves their functionality, integrity, and even vectorality. In this work, we show that a 1-D bilayer device incorporating a rhodopsin proton pump allows us to couple light-driven proton transport to a bioelectronic circuit. We also report that we were able to adapt another distinctive feature of biological signal processing---their widespread use of modifiers, co-factors, and mediator molecules---to regulate and fine-tune the operational characteristics of the bioelectronic device. In our example, we use co-assembly of protein channels and ionophores in the 1-D bilayer to modify the device output levels and response time.

  16. Structure and field emission of graphene layers on top of silicon nanowire arrays

    Science.gov (United States)

    Huang, Bohr-Ran; Chan, Hui-Wen; Jou, Shyankay; Chen, Guan-Yu; Kuo, Hsiu-An; Song, Wan-Jhen

    2016-01-01

    Monolayer graphene was grown on copper foils and then transferred on planar silicon substrates and on top of silicon nanowire (SiNW) arrays to form single- to quadruple-layer graphene films. The morphology, structure, and electron field emission (FE) of these graphene films were investigated. The graphene films on the planar silicon substrates were continuous. The single- to triple-layer graphene films on the SiNW arrays were discontinuous and while the quadruple-layer graphene film featured a mostly continuous area. The Raman spectra of the graphene films on the SiNW arrays showed G and Gʹ bands with a singular-Lorentzian shape together with a weak D band. The D band intensity decreased as the number of graphene layers increased. The FE efficiency of the graphene films on the planar silicon substrates and the SiNW arrays varied with the number of graphene layers. The turn-on field for the single- to quadruple-layer graphene films on planar silicon substrates were 4.3, 3.7, 3.5 and 3.4 V/μm, respectively. The turn-on field for the single- to quadruple-layer graphene films on SiNW arrays decreased to 3.9, 3.3, 3.0 and 3.3 V/μm, respectively. Correlation of the FE with structure and morphology of the graphene films is discussed.

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

    Science.gov (United States)

    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. PMID:25329454

  18. Tuning the electronic band-gap of fluorinated 3C-silicon carbide nanowires

    Science.gov (United States)

    Miranda Durán, Álvaro; Trejo Baños, Alejandro; Pérez, Luis Antonio; Cruz Irisson, Miguel

    The possibility of control and modulation of the electronic properties of silicon carbide nanowires (SiCNWs) by varying the wire diameter is well known. SiCNWs are particularly interesting and technologically important, due to its electrical and mechanical properties, allowing the development of materials with specific electronic features for the design of stable and robust electronic devices. Tuning the band gap by chemical surface passivation constitutes a way for the modification of the electronic band gap of these nanowires. We present, the structural and electronic properties of fluorinated SiCNWs, grown along the [111] crystallographic direction, which are investigated by first principles. We consider nanowires with six diameters, varying from 0.35 nm to 2.13 nm, and eight random covering schemes including fully hydrogen- and fluorine terminated ones. Gibbs free energy of formation and electronic properties were calculated for the different surface functionalization schemes and diameters considered. The results indicate that the stability and band gap of SiCNWs can be tuned by surface passivation with fluorine atoms This work was supported by CONACYT infrastructure project 252749 and UNAM-DGAPA-PAPIIT IN106714. A.M. would like to thank for financial support from CONACyT-Retención. Computing resources from proyect SC15-1-IR-27 of DGTIC-UNAM are acknowledged.

  19. Novel Size and Surface Oxide Effects in Silicon Nanowires as Lithium Battery Anodes

    KAUST Repository

    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.

  20. Spin transport and Hanle effect in silicon nanowires using graphene tunnel barriers

    Science.gov (United States)

    van't Erve, O. M. J.; Friedman, A. L.; Li, C. H.; Robinson, J. T.; Connell, J.; Lauhon, L. J.; Jonker, B. T.

    2015-06-01

    Spin-based devices offer non-volatile, scalable, low power and reprogrammable functionality for emerging device technologies. Here we fabricate nanoscale spintronic devices with ferromagnetic metal/single-layer graphene tunnel barriers used to generate spin accumulation and spin currents in a silicon nanowire transport channel. We report the first observation of spin precession via the Hanle effect in both local three-terminal and non-local spin-valve geometries, providing a direct measure of spin lifetimes and confirmation of spin accumulation and pure spin transport. The use of graphene as the tunnel barrier provides a low-resistance area product contact and clean magnetic switching characteristics, because it smoothly bridges the nanowire and minimizes complicated magnetic domains that otherwise compromise the magnetic behaviour. Utilizing intrinsic two-dimensional layers such as graphene or hexagonal boron nitride as tunnel contacts on nanowires offers many advantages over conventional materials deposited by vapour deposition, enabling a path to highly scaled electronic and spintronic devices.

  1. Vertical Silicon Nanowire Field Effect Transistors with Nanoscale Gate-All-Around

    Science.gov (United States)

    Guerfi, Youssouf; Larrieu, Guilhem

    2016-04-01

    Nanowires are considered building blocks for the ultimate scaling of MOS transistors, capable of pushing devices until the most extreme boundaries of miniaturization thanks to their physical and geometrical properties. In particular, nanowires' suitability for forming a gate-all-around (GAA) configuration confers to the device an optimum electrostatic control of the gate over the conduction channel and then a better immunity against the short channel effects (SCE). In this letter, a large-scale process of GAA vertical silicon nanowire (VNW) MOSFETs is presented. A top-down approach is adopted for the realization of VNWs with an optimum reproducibility followed by thin layer engineering at nanoscale. Good overall electrical performances were obtained, with excellent electrostatic behavior (a subthreshold slope (SS) of 95 mV/dec and a drain induced barrier lowering (DIBL) of 25 mV/V) for a 15-nm gate length. Finally, a first demonstration of dual integration of n-type and p-type VNW transistors for the realization of CMOS inverter is proposed.

  2. Vertical Silicon Nanowire Field Effect Transistors with Nanoscale Gate-All-Around.

    Science.gov (United States)

    Guerfi, Youssouf; Larrieu, Guilhem

    2016-12-01

    Nanowires are considered building blocks for the ultimate scaling of MOS transistors, capable of pushing devices until the most extreme boundaries of miniaturization thanks to their physical and geometrical properties. In particular, nanowires' suitability for forming a gate-all-around (GAA) configuration confers to the device an optimum electrostatic control of the gate over the conduction channel and then a better immunity against the short channel effects (SCE). In this letter, a large-scale process of GAA vertical silicon nanowire (VNW) MOSFETs is presented. A top-down approach is adopted for the realization of VNWs with an optimum reproducibility followed by thin layer engineering at nanoscale. Good overall electrical performances were obtained, with excellent electrostatic behavior (a subthreshold slope (SS) of 95 mV/dec and a drain induced barrier lowering (DIBL) of 25 mV/V) for a 15-nm gate length. Finally, a first demonstration of dual integration of n-type and p-type VNW transistors for the realization of CMOS inverter is proposed. PMID:27094824

  3. In Situ X-ray Diffraction Studies of (De)lithiation Mechanism in Silicon Nanowire Anodes

    KAUST Repository

    Misra, Sumohan

    2012-06-26

    Figure Persented: Silicon is a promising anode material for Li-ion batteries due to its high theoretical specific capacity. From previous work, silicon nanowires (SiNWs) are known to undergo amorphorization during lithiation, and no crystalline Li-Si product has been observed. In this work, we use an X-ray transparent battery cell to perform in situ synchrotron X-ray diffraction on SiNWs in real time during electrochemical cycling. At deep lithiation voltages the known metastable Li 15Si 4 phase forms, and we show that avoiding the formation of this phase, by modifying the SiNW growth temperature, improves the cycling performance of SiNW anodes. Our results provide insight on the (de)lithiation mechanism and a correlation between phase evolution and electrochemical performance for SiNW anodes. © 2012 American Chemical Society.

  4. High-sensitivity pesticide detection via silicon nanowires-supported acetylcholinesterase-based electrochemical sensors

    Science.gov (United States)

    Su, Shao; He, Yao; Zhang, Mingliang; Yang, Kun; Song, Shiping; Zhang, Xiaohong; Fan, Chunhai; Lee, Shuit-Tong

    2008-07-01

    We report the use of a silicon-based nanocomplex, i.e., gold nanoparticles-coated silicon nanowires, for the improvement of acetylcholinesterase (AChE)-based electrochemical sensors for pesticide detection. Owing to the high electrical conductivity of the nanocomplex and its compatibility with the enzyme, the sensor exhibited significantly enhanced performance. The AChE enzyme bound to the surface possessed Michaelis-Menton constant of 81μM, resembling that in its free form. The sensor showed rapid response toward substrate acetylcholine in the concentration range of 1.0μM-1.0mM. This AChE nanosensor could detect as low as 8ng/L dichlorvos, an organophosphate pesticide.

  5. Broadband absorptance enhancement of silicon nanowire arrays with germanium as the substrate

    Science.gov (United States)

    Wang, Han; Xia, Xin-Lin

    2013-08-01

    A composite structure with silicon nanowire arrays on germanium substrate is proposed as a good candidate for highly efficient solar cells. The Bruggeman approximation considering anisotropic wave propagating in uniaxial media is employed to calculate the radiative properties. Meantime, finite-difference time-domain (FDTD) method is used to verify for both normal and oblique incidence. It is found that the composite structure has superior absorption characteristics over thin Si film, particularly near the bandgap. With a thickness only of 4 μm, the composite structure improved the absorptance to above 0.6 across the whole wavelength band with the lattice constant of 100 nm, and the ultimate efficiency about 10% is higher than that of infinite bulk silicon, owing to the combined effects of suppressed reflection and high light trapping capability. To better understand the absorption enhancement process in the composite structure, the photogeneration profiles are provided by using FDTD method.

  6. Onset of ductility and brittleness in silicon nanowires mediated by dislocation nucleation

    International Nuclear Information System (INIS)

    Most studies show that materials at the nano-scale have different mechanical properties than in the bulk state. Semiconductors like silicon and germanium are brittle in the bulk state, but when their size is reduced to the nano-scale they appear to be ductile. Under tensile loading, we performed molecular dynamics simulations on silicon crystalline nanowires of different lengths. We present the details of the obtained mechanisms that led to ductility and brittleness. In the case of ductility, dislocation nucleation was observed with a signature of surface step formation on the surface and in the case of brittleness a cavity was formed after the distinct formation of a wedge-like shape on the surface. Interestingly, a common mechanism taking place behind ductility and brittleness is dislocation nucleation. We believe that the observed mechanisms reveal interesting information for understanding and explaining the size dependent brittle to ductile transition. (paper)

  7. Thermally activated tunneling in porous silicon nanowires with embedded Si quantum dots

    Science.gov (United States)

    Rezvani, S. J.; Pinto, N.; Enrico, E.; D'Ortenzi, L.; Chiodoni, A.; Boarino, L.

    2016-03-01

    Electronic transport properties of porous Si nanowires either with embedded Si quantum dots or with a percolative crystalline path are studied as a function of the temperature for the first time. We show that unlike bulk porous Si, the predesigned structure of the wires results in a single distinct conduction mechanism such as tunneling in the former case and variable range hopping in the latter case. We demonstrate that the geometry of the systems with a large internal surface area and high density of the Si quantum dots have a significant conduction enhancement compared to bulk porous silicon. These results can also improve the understanding of the basis of the different electronic transport mechanisms reported in bulk porous silicon.

  8. High-yield synthesis of silicon carbide nanowires by solar and lamp ablation

    International Nuclear Information System (INIS)

    We report a reasonably high yield (∼50%) synthesis of silicon carbide (SiC) nanowires from silicon oxides and carbon in vacuum, by novel solar and lamp photothermal ablation methods that obviate the need for catalysis, and allow relatively short reaction times (∼10 min) in a nominally one-step process that does not involve toxic reagents. The one-dimensional core/shell β-SiC/SiOx nanostructures—characterized by SEM, TEM, HRTEM, SAED, XRD and EDS—are typically several microns long, with core and outer diameters of about 10 and 30 nm, respectively. HRTEM revealed additional distinctive nanoscale structures that also shed light on the formation pathways. (paper)

  9. InGaN/GaN disk-in-nanowire white light emitting diodes on (001) silicon

    KAUST Repository

    Guo, Wei

    2011-01-01

    High density (? 1011 cm-2) GaN nanowires and InGaN/GaN disk-in-nanowire heterostructures have been grown on (001) silicon substrates by plasma-assisted molecular beam epitaxy. The nanowires exhibit excellent uniformity in length and diameter and a broad emission is obtained by incorporating InGaN disks of varying composition along the length of the nanowires. Monolithic lighting emitting diodes were fabricated with appropriate n- and p-doping of contact layers. White light emission with chromaticity coordinates of x=0.29 and y=0.37 and a correlated color temperature of 5500-6500 K at an injection current of 50 A/ cm2 is measured. The measured external quantum efficiency of the devices do not exhibit any rollover (droop) up to an injection current density of 400 A/ cm2. © 2011 American Institute of Physics.

  10. Preparation of Silicon Nanowire Field-effect Transistor for Chemical and Biosensing Applications.

    Science.gov (United States)

    Wu, Jennifer Yun-Shin; Lin, Chih-Heng; Feng, Mei-Huei; Chen, Chien-Hung; Su, Ping-Chia; Yang, Po-Wen; Zheng, Jian-Ming; Fu, Chang-Wei; Yang, Yuh-Shyong

    2016-01-01

    Surveillance using biomarkers is critical for the early detection, rapid intervention, and reduction in the incidence of diseases. In this study, we describe the preparation of polycrystalline silicon nanowire field-effect transistors (pSNWFETs) that serve as biosensing devices for biomarker detection. A protocol for chemical and biomolecular sensing by using pSNWFETs is presented. The pSNWFET device was demonstrated to be a promising transducer for real-time, label-free, and ultra-high-sensitivity biosensing applications. The source/drain channel conductivity of a pSNWFET is sensitive to changes in the environment around its silicon nanowire (SNW) surface. Thus, by immobilizing probes on the SNW surface, the pSNWFET can be used to detect various biotargets ranging from small molecules (dopamine) to macromolecules (DNA and proteins). Immobilizing a bioprobe on the SNW surface, which is a multistep procedure, is vital for determining the specificity of the biosensor. It is essential that every step of the immobilization procedure is correctly performed. We verified surface modifications by directly observing the shift in the electric properties of the pSNWFET following each modification step. Additionally, X-ray photoelectron spectroscopy was used to examine the surface composition following each modification. Finally, we demonstrated DNA sensing on the pSNWFET. This protocol provides step-by-step procedures for verifying bioprobe immobilization and subsequent DNA biosensing application. PMID:27167162

  11. Morphology, structure and magnetic study of permalloy films electroplated on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lamrani, S. [Centre de Recherche en Technologie des Semi-Conducteurs pour l’énergétique, 2 Bd Frantz Fanon, BP 140 les 7 merveilles, Algiers (Algeria); Université Mouloud Mammeri, TiziOuzou 15000 (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria); Schäfer, R. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Inst. f. Metallic Materials, Helmholtz str. 20, D-01069 Dresden (Germany); Hemmous, M. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria); Neu, V.; Pofahl, S. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Inst. f. Metallic Materials, Helmholtz str. 20, D-01069 Dresden (Germany); Hadjersi, T. [Centre de Recherche en Technologie des Semi-Conducteurs pour l’énergétique, 2 Bd Frantz Fanon, BP 140 les 7 merveilles, Algiers (Algeria); Benbrahim, N. [Université Mouloud Mammeri, TiziOuzou 15000 (Algeria)

    2015-12-15

    We report the effect of deposition potential on the morphology, structure and magnetic properties of Ni{sub 80}Fe{sub 20} (Permalloy: Py) deposits, elaborated by electrochemical process onto silicon nanowires (SiNWs). The morphology of SiNWs and Py/SiNWs were performed with scanning electron microscopy (SEM). The SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. The analysis of X-ray diffraction spectra shows a change in the texture with the deposition potential. The grain size, the lattice parameter and the strain were studied as a function of the deposition potentials. From hysteresis loops, we have shown that the magnetization easy axis is the plane of the samples. - Highlights: • Permalloy deposits were elaborated by electrochemical process onto silicon nanowires (SiNWs). • SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. • The magnetization easy axis was found to be in the plane of samples.

  12. Selectively deposited silver coatings on gold-capped silicon nanowires for surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Becker, M; Stelzner, Th; Steinbrück, A; Berger, A; Liu, J; Lerose, D; Gösele, U; Christiansen, S

    2009-06-01

    Gold caps on silicon nanowires are selectively coated with silver by autometallography (electroless deposition). Changing the conditions of silver deposition, a variety of different coating morphologies can be produced [figure: see text]. The different silver coating morphologies are investigated in terms of their capabilities for surface enhanced Raman scattering (SERS) experiments.Gold caps on silicon nanowires are hemispherical and only a few tens of nanometers in diameter when grown from metal catalysts by the vapor-liquid-solid growth mechanism using chemical vapor deposition. These gold caps are capable of enhancing Raman signals based on the surface-enhanced Raman scattering effect. The Raman signal can be enhanced even further (by at least one order of magnitude) when silver is selectively deposited onto these gold caps by autometallography (electroless deposition). By changing the silver deposition conditions, different coating morphologies can be realized on the gold caps that range from very thin, smooth layers to uneven and extremely rough coatings. The SERS signal enhancement and the spatial homogeneity of the achievable enhancement are compared for the different silver coatings using a model dye molecule. PMID:19399821

  13. Optical Properties of Silicon Nanowires Fabricated by Environment-Friendly Chemistry

    Science.gov (United States)

    Gonchar, Kirill A.; Zubairova, Alsu A.; Schleusener, Alexander; Osminkina, Liubov A.; Sivakov, Vladimir

    2016-08-01

    Silicon nanowires (SiNWs) were fabricated by metal-assisted chemical etching (MACE) where hydrofluoric acid (HF), which is typically used in this method, was changed into ammonium fluoride (NH4F). The structure and optical properties of the obtained SiNWs were investigated in details. The length of the SiNW arrays is about 2 μm for 5 min of etching, and the mean diameter of the SiNWs is between 50 and 200 nm. The formed SiNWs demonstrate a strong decrease of the total reflectance near 5-15 % in the spectral region λ < 1 μm in comparison to crystalline silicon (c-Si) substrate. The interband photoluminescence (PL) and Raman scattering intensities increase strongly for SiNWs in comparison with the corresponding values of the c-Si substrate. These effects can be interpreted as an increase of the excitation intensity of SiNWs due to the strong light scattering and the partial light localization in an inhomogeneous optical medium. Along with the interband PL was also detected the PL of SiNWs in the spectral region of 500-1100 nm with a maximum at 750 nm, which can be explained by the radiative recombination of excitons in small Si nanocrystals at nanowire sidewalls in terms of a quantum confinement model. So SiNWs, which are fabricated by environment-friendly chemistry, have a great potential for use in photovoltaic and photonics applications.

  14. Morphology, structure and magnetic study of permalloy films electroplated on silicon nanowires

    International Nuclear Information System (INIS)

    We report the effect of deposition potential on the morphology, structure and magnetic properties of Ni80Fe20 (Permalloy: Py) deposits, elaborated by electrochemical process onto silicon nanowires (SiNWs). The morphology of SiNWs and Py/SiNWs were performed with scanning electron microscopy (SEM). The SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. The analysis of X-ray diffraction spectra shows a change in the texture with the deposition potential. The grain size, the lattice parameter and the strain were studied as a function of the deposition potentials. From hysteresis loops, we have shown that the magnetization easy axis is the plane of the samples. - Highlights: • Permalloy deposits were elaborated by electrochemical process onto silicon nanowires (SiNWs). • SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. • The magnetization easy axis was found to be in the plane of samples

  15. Probing protein complexes inside living cells using a silicon nanowire-based pull-down assay

    Science.gov (United States)

    Choi, Sojoong; Kim, Hyunju; Kim, So Yeon; Yang, Eun Gyeong

    2016-06-01

    Most proteins perform their functions as interacting complexes. Here we propose a novel method for capturing an intracellular protein and its interacting partner out of living cells by utilizing intracellular access of antibody modified vertical silicon nanowire arrays whose surface is covered with a polyethylene glycol layer to prevent strong cell adhesion. Such a feature facilitates the removal of cells by simple washing, enabling subsequent detection of a pulled-down protein and its interacting partner, and further assessment of a drug-induced change in the interacting complex. Our new SiNW-based tool is thus suitable for authentication of protein networks inside living cells.Most proteins perform their functions as interacting complexes. Here we propose a novel method for capturing an intracellular protein and its interacting partner out of living cells by utilizing intracellular access of antibody modified vertical silicon nanowire arrays whose surface is covered with a polyethylene glycol layer to prevent strong cell adhesion. Such a feature facilitates the removal of cells by simple washing, enabling subsequent detection of a pulled-down protein and its interacting partner, and further assessment of a drug-induced change in the interacting complex. Our new SiNW-based tool is thus suitable for authentication of protein networks inside living cells. Electronic supplementary information (ESI) available: Materials, experimental methods and Fig. S1-S8. See DOI: 10.1039/c6nr00171h

  16. Hybrid nanocomposites based on conducting polymer and silicon nanowires for photovoltaic application

    International Nuclear Information System (INIS)

    Hybrid nanocomposites based on a nanoscale combination of organic and inorganic semiconductors are a promising way to enhance the performance of solar cells through a higher aspect ratio of the interface and the good processability of polymers. Nanocomposites are based on a heterojunction network between poly (2-methoxy-5-(2-ethyhexyl-oxy)-p-phenylenevinylene) (MEH-PPV) as an organic electron donor and silicon nanowires (SiNWs) as an inorganic electron acceptor. Nanowires (NWs) seem to be a promising material for this purpose, as they provide a large surface area for contact with the polymer and a designated conducting pathway whilst their volume is low. In this paper, silicon nanowires are introduced by mixing them into the polymer matrix. Hybrid nanocomposites films were deposited onto ITO substrate by spin coating method. Optical properties and photocurrent response were investigated. Charge transfer between the polymer and SiNWs has been demonstrated through photoluminescence measurements. The photocurrent density of ITO/MEH-PPV:SiNWs/Al structures have been obtained by J–V characteristics. The Jsc value is about 0.39 µA/cm2. - Highlights: • SiNWs synthesis by Vapor–Liquid–Solid (VLS) mechanism. • SiNWs contribution to absorption spectra enhancement of MEH-PPV:SiNWs nanocomposites. • Decrease of PL intensity of MEH-PPV by addition of SiNWs. • Charge transfer process was taken place. • ITO/MEH-PPV:SiNWs/Al structure shows a photovoltaic effect, with a FF of 0.32

  17. Solid-state diffusion as an efficient doping method for silicon nanowires and nanowire field effect transistors

    International Nuclear Information System (INIS)

    In this work we investigate doping by solid-state diffusion from a doped oxide layer, obtained by plasma-enhanced chemical vapor deposition (PECVD), as a means for selectively doping silicon nanowires (NWs). We demonstrate both n-type (phosphorous) and p-type (boron) doping up to concentrations of 1020 cm-3, and find that this doping mechanism is more efficient for NWs as opposed to planar substrates. We observe no diameter dependence in the range of 25 to 80 nm, which signifies that the NWs are uniformly doped. The drive-in temperature (800-950 deg. C) can be used to adjust the actual doping concentration in the range 2 x 1018 to 1020 cm-3. Furthermore, we have fabricated NMOS and PMOS devices to show the versatility of this approach and the possibility of achieving segmented doping of NWs. The devices show high Ion/Ioff ratios of around 107 and, especially for the PMOS, good saturation behavior and low hysteresis.

  18. Thermal stability of comp ound stucture of silicon nanowire encapsulated in carb on nanotub es%碳纳米管包裹的硅纳米线复合结构的热稳定性研究∗

    Institute of Scientific and Technical Information of China (English)

    卢顺顺; 张晋敏; 郭笑天; 高廷红; 田泽安; 何帆; 贺晓金; 吴宏仙; 谢泉

    2016-01-01

    To guide the experiment research, the thermal stability of composite silicon nanowire encapsulated in carbon nanotubes is investigated by computer simulation. The cubic-diamond-structured silicon nanowires with the same diameter and [111] orientationt are filled in some armchaired single-walled carbon nanotubes. The heat process of compound structure of silicon nanowire encapsulated in carbon nanotubes is simulated by classical molecular dynamic method. Through the visualization and energy analysis method, the thermal stability of composite structure is studied. The changes in the thermal stability of silicon nanowires and carbon nanotubes are explained by the relationship between carbon nanotube space constraint and van der Waals force. It is found that the diameter of the carbon nanotubes is closely related to the thermal stability of silicon nanowires inside. When the nanotube diameter is small, thermal stability of silicon nanowires increases;when the nanotube diameter increases up to a certain size, the thermal stability of silicon nanowires will suddenly drop significantly: until the distance between silicon nanowires and the wall of carbon nanotube is greater than 1 nm, the thermal stability of silicon nanowires will be restored. On the other hand, silicon nanowires filled into the carbon nanotubes have an effect of reducing the thermal stability of carbon nanotubes.

  19. Highly robust silicon nanowire/graphene core-shell electrodes without polymeric binders

    Science.gov (United States)

    Lee, Sang Eon; Kim, Han-Jung; Kim, Hwanjin; Park, Jong Hyeok; Choi, Dae-Geun

    2013-09-01

    A large theoretical charge storage capacity along with a low discharge working potential renders silicon a promising anode material for high energy density lithium ion batteries. However, up to 400% volume expansion during charge-discharge cycling coupled with a low intrinsic electronic conductivity causes pulverization and fracture, thus inhibiting silicon's widespread use in practical applications. We report herein on a low cost approach to fabricate hybrid silicon nanowire (SiNW)/graphene nanostructures that exhibit enhanced cycle performance with the capability of retaining more than 90% of their initial capacity after 50 cycles. We also demonstrate the use of hot-pressing in the absence of any common polymer binder such as PVDF to bind the hybrid structure to the current collector. The applied heat and pressure ensure strong adhesion between the SiNW/graphene nano-composite and current collector. This facile yet strong binding method is expected to find use in the further development of polymer-binder free anodes for lithium ion batteries.A large theoretical charge storage capacity along with a low discharge working potential renders silicon a promising anode material for high energy density lithium ion batteries. However, up to 400% volume expansion during charge-discharge cycling coupled with a low intrinsic electronic conductivity causes pulverization and fracture, thus inhibiting silicon's widespread use in practical applications. We report herein on a low cost approach to fabricate hybrid silicon nanowire (SiNW)/graphene nanostructures that exhibit enhanced cycle performance with the capability of retaining more than 90% of their initial capacity after 50 cycles. We also demonstrate the use of hot-pressing in the absence of any common polymer binder such as PVDF to bind the hybrid structure to the current collector. The applied heat and pressure ensure strong adhesion between the SiNW/graphene nano-composite and current collector. This facile yet strong

  20. NanoElectronics and BioElectronics

    Science.gov (United States)

    Srivastava, Deepak

    2001-01-01

    This viewgraph presentation reviews the use of Carbon Nanotube electronics in the bioelectronics. Included is a brief review of the carbon nanotube manufacturing, the use of carbon nanotubes in Atomic Force Microscopy (AFM), and Computational Nanotechnology, that allows designers to understand nanotube characteristics and serves as a design tool.

  1. Fabrication of three-dimensional MIS nano-capacitor based on nano-imprinted single crystal silicon nanowire arrays

    KAUST Repository

    Zhai, Yujia

    2012-11-26

    We report fabrication of single crystalline silicon nanowire based-three-dimensional MIS nano-capacitors for potential analog and mixed signal applications. The array of nanowires is patterned by Step and Flash Imprint Lithography (S-FIL). Deep silicon etching (DSE) is used to form the nanowires with high aspect ratio, increase the electrode area and thus significantly enhance the capacitance. High-! dielectric is deposited by highly conformal atomic layer deposition (ALD) Al2O3 over the Si nanowires, and sputtered metal TaN serves as the electrode. Electrical measurements of fabricated capacitors show the expected increase of capacitance with greater nanowire height and decreasing dielectric thickness, consistent with calculations. Leakage current and time-dependent dielectric breakdown (TDDB) are also measured and compared with planar MIS capacitors. In view of greater interest in 3D transistor architectures, such as FinFETs, 3D high density MIS capacitors offer an attractive device technology for analog and mixed signal applications. - See more at: http://www.eurekaselect.com/105099/article#sthash.EzeJxk6j.dpuf

  2. Fabrication of silicon nanowire arrays by near-field laser ablation and metal-assisted chemical etching

    Science.gov (United States)

    Brodoceanu, D.; Alhmoud, H. Z.; Elnathan, R.; Delalat, B.; Voelcker, N. H.; Kraus, T.

    2016-02-01

    We present an elegant route for the fabrication of ordered arrays of vertically-aligned silicon nanowires with tunable geometry at controlled locations on a silicon wafer. A monolayer of transparent microspheres convectively assembled onto a gold-coated silicon wafer acts as a microlens array. Irradiation with a single nanosecond laser pulse removes the gold beneath each focusing microsphere, leaving behind a hexagonal pattern of holes in the gold layer. Owing to the near-field effects, the diameter of the holes can be at least five times smaller than the laser wavelength. The patterned gold layer is used as catalyst in a metal-assisted chemical etching to produce an array of vertically-aligned silicon nanowires. This approach combines the advantages of direct laser writing with the benefits of parallel laser processing, yielding nanowire arrays with controlled geometry at predefined locations on the silicon surface. The fabricated VA-SiNW arrays can effectively transfect human cells with a plasmid encoding for green fluorescent protein.

  3. Influence of Cu as a catalyst on the properties of silicon nanowires synthesized by the vapour-solid-solid mechanism

    International Nuclear Information System (INIS)

    Unlike typical Au used as a catalyst for the synthesis of silicon nanowires via the vapour-liquid-solid mechanism, Cu has been found to induce a synthesis process governed by the vapour-solid-solid mechanism. Moreover, the temperature window for obtaining high-quality wires with Cu has been found to be relatively smaller than that shown by the Au: from 600 to 650 deg. C. However, high-resolution transmission electron microscopy analysis reveals significant new properties of the nanowires obtained. They have the peculiarity of successively switching the silicon structure from diamond to the wurtzite phase along the growth direction. This change of the crystalline structure implies that it has an important impact on the transport properties and characteristics of electronic devices. The results will be important for the future integration and application of silicon, where electrical and thermal transport properties play a significant role

  4. The influence of passivation and photovoltaic properties of α-Si:H coverage on silicon nanowire array solar cells.

    Science.gov (United States)

    Li, Kuntang; Wang, Xiuqin; Lu, Pengfei; Ding, Jianning; Yuan, Ningyi

    2013-01-01

    Silicon nanowire (SiNW) arrays for radial p-n junction solar cells offer potential advantages of light trapping effects and quick charge collection. Nevertheless, lower open circuit voltages (Voc) lead to lower energy conversion efficiencies. In such cases, the performance of the solar cells depends critically on the quality of the SiNW interfaces. In this study, SiNW core-shell solar cells have been fabricated by growing crystalline silicon (c-Si) nanowires via the metal-assisted chemical etching method and by depositing hydrogenated amorphous silicon (α-Si:H) via the plasma-enhanced chemical vapor deposition (PECVD) method. The influence of deposition parameters on the coverage and, consequently, the passivation and photovoltaic properties of α-Si:H layers on SiNW solar cells have been analyzed. PMID:24059343

  5. Fabrication of CoFe2O4 ferrite nanowire arrays in porous silicon template and their local magnetic properties

    Science.gov (United States)

    Hui, Zheng; Man-Gui, Han; Long-Jiang, Deng

    2016-02-01

    CoFe2O4 ferrite nanowire arrays are fabricated in porous silicon templates. The porous silicon templates are prepared via metal-assisted chemical etching with gold (Au) nanoparticles as the catalyst. Subsequently, CoFe2O4 ferrite nanowires are successfully synthesized into porous silicon templates by the sol-gel method. The magnetic hysteresis loop of nanowire array shows an isotropic feature of magnetic properties. The coercivity and squareness ratio (Mr/Ms) of ensemble nanowires are found to be 630 Oe (1 Oe, = 79.5775 A·m-1 and 0.4 respectively. However, the first-order reversal curve (FORC) is adopted to reveal the probability density function of local magnetostatic properties (i.e., interwire interaction field and coercivity). The FORC diagram shows an obvious distribution feature for interaction field and coercivity. The local coercivity with a value of about 1000 Oe is found to have the highest probability. Project supported by the National Natural Science Foundation of China (Grant No. 61271039), the Scientific Projects of Sichuan Province, China (Grant No. 2015HH0016), and the Natural Science Foundations of Zhejiang Province, China (Grant Nos. LQ12E02001 and Y107255).

  6. A Monolithically Integrated Gallium Nitride Nanowire/Silicon Solar Cell Photocathode for Selective Carbon Dioxide Reduction to Methane.

    Science.gov (United States)

    Wang, Yichen; Fan, Shizhao; AlOtaibi, Bandar; Wang, Yongjie; Li, Lu; Mi, Zetian

    2016-06-20

    A gallium nitride nanowire/silicon solar cell photocathode for the photoreduction of carbon dioxide (CO2 ) is demonstrated. Such a monolithically integrated nanowire/solar cell photocathode offers several unique advantages, including the absorption of a large part of the solar spectrum and highly efficient carrier extraction. With the incorporation of copper as the co-catalyst, the devices exhibit a Faradaic efficiency of about 19 % for the 8e(-) photoreduction to CH4 at -1.4 V vs Ag/AgCl, a value that is more than thirty times higher than that for the 2e(-) reduced CO (ca. 0.6 %). PMID:27128407

  7. Graded index and randomly oriented core-shell silicon nanowires with broadband and wide angle antireflection for photovoltaic cell applications

    CERN Document Server

    Pignalosa, P; Qiao, L; Tseng, M; Yi, Yasha

    2011-01-01

    Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm) and wide angle (from normal incidence to 60\\degree) antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si) nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

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

    International Nuclear Information System (INIS)

    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, SF6 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 SF6 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-04-15

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

  10. Photonic light trapping in silicon nanowire arrays: deriving and overcoming the physical limitations

    CERN Document Server

    Schmitt, Sebastian W

    2016-01-01

    Hexagonally aligned, free-standing silicon nanowire (SiNW) arrays serve as photonic resonators which, as compared to a silicon (Si) thin film, do not only absorb more visible (VIS) and near-infrared (NIR) light, but also show an inherent photonic light concentration that enhances their performance as solar absorbers. Using numerical simulations we show, how light concentration is induced by high optical cross sections of the individual SiNWs but cannot be optimized independently of the SiNW array absorption. While an ideal spatial density exists, for which the SiNW array absorption for VIS and NIR wavelengths reaches a maximum, the spatial correlation of SiNWs in an array suppresses the formation of optical Mie modes responsible for light concentration. We show that different from SiNWs with straight sidewalls, arrays of inverted silicon nanocones (SiNCs) permit to avoid the mode suppression. In fact they give rise to an altered set of photonic modes which is induced by the spatial correlation of SiNCs in the...

  11. Inuence of Gold-Copper Alloy Catalyst Composition on Crystal Growth and Dopant Distribution in Silicon and Germanium Nanowires

    Science.gov (United States)

    Connell, Justin G.

    A combination of local electrode atom probe tomography (LEAP) and transmission electron microscopy characterization were used to investigate growth of and dopant incorporation in silicon and germanium nanowires (Si and GeNWs) via the vapor-liquid- solid (VLS) mechanism. A sample structure was developed that enabled isolation of the catalyst-mediated contribution to doping in individual nanowires during LEAP analysis. As a result, the distribution coefficient - a thermodynamic quantity describing axial junction abruptness - was measured in nanowires for the first time, providing a fundamental framework for comparison of junction abruptness in nanowires. These investigations also enabled the identification of a previously unknown radial anisotropy in dopant incorporation through the catalyst, with variations in dopant concentration across the VLS-defined diameter of the nanowire as large as two orders of magnitude. Finite element modeling of the doping process, coupled with in situ TEM observations reported in the literature, suggests that this radially inhomogeneous dopant distribution is a direct consequence of growth from a faceted liquid-solid interface, rather than the commonly assumed planar interface. Au-Cu alloy catalysts were explored as alternatives to Au-catalyzed VLS nanowire growth as a means to alleviate or eliminate axial and radial doping gradients in nanowires. Both an aqueous solution and electron beam lithographic method for creating Au-Cu alloy catalysts of controlled composition were developed, and GeNW growth was demonstrated from both types of catalyst. LEAP characterization of Au-Cu alloy catalyzed P-doped GeNWs revealed that alloying with Cu results in more abrupt axial doping junctions, as well as a more homogeneous radial distribution of dopants within the VLS-defined diameter of the nanowire.

  12. Ultra-thin superconducting film coated silicon nitride nanowire resonators for low-temperature applications

    Science.gov (United States)

    Sebastian, Abhilash; Zhelev, Nikolay; de Alba, Roberto; Parpia, Jeevak

    We demonstrate fabrication of high stress silicon nitride nanowire resonators with a thickness and width of less than 50 nm intended to be used as probes for the study of superfluid 3He. The resonators are fabricated as doubly-clamped wires/beams using a combination of electron-beam lithography and wet/dry etching techniques. We demonstrate the ability to suspend (over a trench of depth ~8 µm) wires with a cross section as small as 30 nm, covered with a 20 nm superconducting film, and having lengths up to 50 µm. Room temperature resonance measurements were carried out by driving the devices using a piezo stage and detecting the motion using an optical interferometer. The results show that metalizing nano-mechanical resonators not only affects their resonant frequencies but significantly reduce their quality factor (Q). The devices are parametrically pumped by modulating the system at twice its fundamental resonant frequency, which results in observed amplification of the signal. The wires show self-oscillation with increasing modulation strength. The fabricated nanowire resonators are intended to be immersed in the superfluid 3He. By tracking the resonant frequency and the Q of the various modes of the wire versus temperature, we aim to probe the superfluid gap structure.

  13. The design of a new spiking neuron using dual work function silicon nanowire transistors

    Energy Technology Data Exchange (ETDEWEB)

    Bindal, Ahmet [Computer Engineering Department, San Jose State University, One Washington Square, San Jose, CA 95192 (United States); Hamedi-Hagh, Sotoudeh [Electrical Engineering Department, San Jose State University, One Washington Square, San Jose, CA 95192 (United States)

    2007-03-07

    A new spike neuron cell is designed using vertically grown, undoped silicon nanowire transistors. This study presents an entire design cycle from designing and optimizing vertical nanowire transistors for minimal power dissipation to realizing a neuron cell and measuring its dynamic power consumption, performance and layout area. The design cycle starts with determining individual metal gate work functions for NMOS and PMOS transistors as a function of wire radius to produce a 300 mV threshold voltage. The wire radius and effective channel length are subsequently varied to find a common body geometry for both transistors that yields smaller than 1 pA OFF current while producing maximum drive currents. A spike neuron cell is subsequently built using these transistors to measure its transient performance, power dissipation and layout area. Post-layout simulation results indicate that the neuron consumes 0.397 {mu}W to generate a +1 V and 1.12 {mu}W to generate a -1 V output pulse for a fan-out of five synapses at 500 MHz; the power dissipation increases by approximately 3 nW for each additional synapse at the output for generating either pulse. The neuron circuit occupies approximately 0.27 {mu}m{sup 2}.

  14. Surface-Coating Regulated Lithiation Kinetics and Degradation in Silicon Nanowires for Lithium Ion Battery

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Langli; Yang, Hui; Yan, Pengfei; Travis, Jonathan J.; Lee, Younghee; Liu, Nian; Piper, Daniela M.; Lee, Se-Hee; Zhao, Peng; George, Steven M.; Zhang, Jiguang; Cui, Yi; Zhang, Sulin; Ban, Chunmei; Wang, Chong M.

    2015-05-26

    Silicon (Si)-based materials hold promise as the next-generation anodes for high-energy lithium (Li)-ion batteries. Enormous research efforts have been undertaken to mitigate the chemo-mechanical failure due to the large volume changes of Si during lithiation and delithiation cycles. It has been found nanostructured Si coated with carbon or other functional materials can lead to significantly improved cyclability. However, the underlying mechanism and comparative performance of different coatings remain poorly understood. Herein, using in situ transmission electron microscopy (TEM) through a nanoscale half-cell battery, in combination with chemo-mechanical simulation, we explored the effect of thin (~5 nm) alucone and Al2O3 coatings on the lithiation kinetics of Si nanowires (SiNWs). We observed that the alucone coating leads to a “V-shaped” lithiation front of the SiNWs , while the Al2O3 coating yields an “H-shaped” lithiation front. These observations indicate that the difference between the Li surface diffusivity and bulk diffusivity of the coatings dictates lithiation induced morphological evolution in the nanowires. Our experiments also indicate that the reaction rate in the coating layer can be the limiting step for lithiation and therefore critically influences the rate performance of the battery. Further, the failure mechanism of the Al2O3 coated SiNWs was also explored. Our studies shed light on the design of high capacity, high rate and long cycle life Li-ion batteries.

  15. Quantifying the Traction Force of a Single Cell by Aligned Silicon Nanowire Array

    KAUST Repository

    Li, Zhou

    2009-10-14

    The physical behaviors of stationary cells, such as the morphology, motility, adhesion, anchorage, invasion and metastasis, are likely to be important for governing their biological characteristics. A change in the physical properties of mammalian cells could be an indication of disease. In this paper, we present a silicon-nanowire-array based technique for quantifying the mechanical behavior of single cells representing three distinct groups: normal mammalian cells, benign cells (L929), and malignant cells (HeLa). By culturing the cells on top of NW arrays, the maximum traction forces of two different tumor cells (HeLa, L929) have been measured by quantitatively analyzing the bending of the nanowires. The cancer cell exhibits a larger traction force than the normal cell by ∼20% for a HeLa cell and ∼50% for a L929 cell. The traction forces have been measured for the L929 cells and mechanocytes as a function of culture time. The relationship between cells extending area and their traction force has been investigated. Our study is likely important for studying the mechanical properties of single cells and their migration characteristics, possibly providing a new cellular level diagnostic technique. © 2009 American Chemical Society.

  16. Exact comprehensive equations for the photon management properties of silicon nanowire

    Science.gov (United States)

    Li, Yingfeng; Li, Meicheng; Li, Ruike; Fu, Pengfei; Wang, Tai; Luo, Younan; Mbengue, Joseph Michel; Trevor, Mwenya

    2016-01-01

    Unique photon management (PM) properties of silicon nanowire (SiNW) make it an attractive building block for a host of nanowire photonic devices including photodetectors, chemical and gas sensors, waveguides, optical switches, solar cells, and lasers. However, the lack of efficient equations for the quantitative estimation of the SiNW’s PM properties limits the rational design of such devices. Herein, we establish comprehensive equations to evaluate several important performance features for the PM properties of SiNW, based on theoretical simulations. Firstly, the relationships between the resonant wavelengths (RW), where SiNW can harvest light most effectively, and the size of SiNW are formulized. Then, equations for the light-harvesting efficiency at RW, which determines the single-frequency performance limit of SiNW-based photonic devices, are established. Finally, equations for the light-harvesting efficiency of SiNW in full-spectrum, which are of great significance in photovoltaics, are established. Furthermore, using these equations, we have derived four extra formulas to estimate the optimal size of SiNW in light-harvesting. These equations can reproduce majority of the reported experimental and theoretical results with only ~5% error deviations. Our study fills up a gap in quantitatively predicting the SiNW’s PM properties, which will contribute significantly to its practical applications. PMID:27103087

  17. Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

    Institute of Scientific and Technical Information of China (English)

    YANG Cheng; ZHANG Gang; LEE Dae-Young; LI Hua-Min; LIM Young-Dae; Y00 Won Jong; PARK Young-Jun; KIM Jong-Min

    2011-01-01

    Self-assembly of silicon nanowire(SiNW)arrays is studied using SF6/02 plasma treatment. The self-assembly method can be applied to single- and poly-crystalline Si substrates. Plasma conditions can control the length and diameter of the SiNW arrays. Lower reflectance of the wire arrays over the wavelength range 200-1100nm is obtained. The conducting transparent indium-tin-oxide(ITO) electrode can be fully coated on the self-assembled SiNW arrays by sputtering. The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating. An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.

  18. Nanotubes, nanobelts, nanowires, and nanorods of silicon carbide from the wheat husks

    Energy Technology Data Exchange (ETDEWEB)

    Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Feng, J.; Qadri, S. N.; Caldwell, J. D. [Materials Science and Component Technology Directorate, Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

    2015-09-14

    Nanotubes, nanowires, nanobelts, and nanorods of SiC were synthesized from the thermal treatment of wheat husks at temperatures in excess of 1450 °C. From the analysis based on x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, it has been found that the processed samples of wheat husk consisted of 2H and 3C polytypes of SiC exhibiting the nanostructure shapes. These nanostructures of silicon carbide formed from wheat husks are of technological importance for designing advance composites, applications in biotechnology, and electro-optics. The thermodynamics of the formation of SiC is discussed in terms of the rapid solid state reaction between hydrocarbons and silica on the molecular scale, which is inherently present in the wheat husks.

  19. Nanotubes, nanobelts, nanowires, and nanorods of silicon carbide from the wheat husks

    International Nuclear Information System (INIS)

    Nanotubes, nanowires, nanobelts, and nanorods of SiC were synthesized from the thermal treatment of wheat husks at temperatures in excess of 1450 °C. From the analysis based on x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, it has been found that the processed samples of wheat husk consisted of 2H and 3C polytypes of SiC exhibiting the nanostructure shapes. These nanostructures of silicon carbide formed from wheat husks are of technological importance for designing advance composites, applications in biotechnology, and electro-optics. The thermodynamics of the formation of SiC is discussed in terms of the rapid solid state reaction between hydrocarbons and silica on the molecular scale, which is inherently present in the wheat husks

  20. Temperature and directional dependences of the infrared dielectric function of free standing silicon nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Kazan, M.; Bruyant, A.; Sedaghat, Z.; Arnaud, L.; Blaize, S.; Royer, P. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, Universite de Technologie de Troyes, CNRS FRE 2848, 12 Rue Marie Curie, 10010 Troyes, Cedex (France)

    2011-03-15

    An approach to calculate the infrared dielectric function of semiconductor nanostructures is presented and applied to silicon (Si) nanowires (NW's). The phonon modes symmetries and frequencies are calculated by means of the elastic continuum medium theory. The modes strengths and damping are calculated from a model for lattice dynamics and perturbation theory. The data are used in anisotropic Lorentz oscillator model to generate the temperature and directional dependences of the infrared dielectric function of free standing Si NW's. Our results showed that in the direction perpendicular to the NW axis, the complex dielectric function is identical to that of bulk Si. However, along the NW axis, the infrared dielectric function is a strong function of the wavelength. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Synthesis, structure and photoelectrochemical properties of single crystalline silicon nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Dalchiele, E.A., E-mail: dalchiel@fing.edu.u [Instituto de Fisica, Facultad de Ingenieria, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Martin, F.; Leinen, D. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Departamentos de Fisica Aplicada and Ingenieria Quimica, Universidad de Malaga, Campus de Teatinos s/n, E29071 Malaga (Spain); Marotti, R.E. [Instituto de Fisica, Facultad de Ingenieria, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Ramos-Barrado, J.R. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Departamentos de Fisica Aplicada and Ingenieria Quimica, Universidad de Malaga, Campus de Teatinos s/n, E29071 Malaga (Spain)

    2010-01-31

    In the present work, n-type silicon nanowire (n-SiNW) arrays have been synthesized by self-assembly electroless metal deposition (EMD) nanoelectrochemistry. The synthesized n-SiNW arrays have been submitted to scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and optical studies. Initial probes of the solar device conversion properties and the photovoltaic parameters such as short-circuit current, open-circuit potential, and fill factor of the n-SiNW arrays have been explored using a liquid-junction in a photoelectrochemical (PEC) system under white light. Moreover, a direct comparison between the PEC performance of a polished n-Si(100) and the synthesized n-SiNW array photoelectrodes has been done. The PEC performance was significantly enhanced on the n-SiNWs photoelectrodes compared with that on polished n-Si(100).

  2. Stability and evolution of low-surface-tension metal catalyzed growth of silicon nanowires

    Science.gov (United States)

    Yu, Linwei; Fortuna, Franck; O'Donnell, Benedict; Patriache, Gilles; Roca i Cabarrocas, Pere

    2011-03-01

    Low-surface-tension metals were predicted to be insufficient to catalyze the growth of silicon nanowires (SiNWs) in vapor-liquid-solid (VLS) mode while counter examples do exist, for example, in the tin- or indium-catalyzed SiNWs. This puzzle remains largely unresolved. We first examine the local tension-force-balance in a tin-catalyzed SiNW by using a cross-section analysis. We found that the existence of an ultrathin sidewall-spreading catalyst layer helps to stabilize the catalyst drop during growth. The predicted contact-angle evolution, by an energetic balance model, is also supported by the experimental data. These results bring critical understanding on the low-surface-tension catalyzed VLS process.

  3. Detection of DNA of genetically modified maize by a silicon nanowire field-effect transistor

    International Nuclear Information System (INIS)

    A silicon nanowire field-effect transistor based sensor (SiNW-FET) has been proved to be the most sensitive and powerful device for bio-detection applications. In this paper, SiNWs were first fabricated by using our recently developed deposition and etching under angle technique (DEA), then used to build up the complete SiNW device based biosensor. The fabricated SiNW biosensor was used to detect DNA of genetically modified maize. As the DNA of the genetically modified maize has particular DNA sequences of 35S promoter, we therefore designed 21 mer DNA oligonucleotides, which are used as a receptor to capture the transferred DNA of maize. In our work, the SiNW biosensor could detect DNA of genetically modified maize with concentrations down to about 200 pM

  4. Near-theoretical fracture strengths in native and oxidized silicon nanowires

    Science.gov (United States)

    DelRio, Frank W.; White, Ryan M.; Krylyuk, Sergiy; Davydov, Albert V.; Friedman, Lawrence H.; Cook, Robert F.

    2016-08-01

    In this letter, fracture strengths σ f of native and oxidized silicon nanowires (SiNWs) were determined via atomic force microscopy bending experiments and nonlinear finite element analysis. In the native SiNWs, σ f in the Si was comparable to the theoretical strength of Si, ≈22 GPa. In the oxidized SiNWs, σ f in the SiO2 was comparable to the theoretical strength of SiO2, ≈6 to 12 GPa. The results indicate a change in the failure mechanism between native SiNWs, in which fracture originated via inter-atomic bond breaking or atomic-scale defects in the Si, and oxidized SiNWs, in which fracture initiated from surface roughness or nano-scale defects in the SiO2.

  5. Origin of photoluminescence from silicon nanowires prepared by metal induced etching (MIE)

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Shailendra K., E-mail: shailendra.saxena3@gmail.com; Rai, Hari. M.; Late, Ravikiran [Material Research Laboratory, Discipline of Physics, School of Basic Sciences, Indian Institute of Technology Indore, Madhya Pradesh-452017 (India); Sagdeo, Pankaj R.; Kumar, Rajesh [Material Research Laboratory, Discipline of Physics, School of Basic Sciences, Indian Institute of Technology Indore, Madhya Pradesh-452017 (India); Material Science and Engineering Group, Indian Institute of Technology Indore, Madhya Pradesh-452017 (India)

    2015-05-15

    In this present study the origin of luminescence from silicon nanowires (SiNws) has been studied. SiNWs are fabricated on Si substrate by metal induced chemical etching (MIE). Here it is found that the band gap of SiNWs is higher than the gap of luminescent states in SiNWs which leads to the effect of Si=O bond. The band gap is estimated from diffuse reflectance analysis. Here we observe that band gap can be tailored depending on size (quantum confinement) but photoluminescence (PL) from all the sample is found to be fixed at 1.91 eV. This study is important for the understanding of origin of photoluminescence.

  6. Spin-on-doping for output power improvement of silicon nanowire array based thermoelectric power generators

    International Nuclear Information System (INIS)

    The output power of a silicon nanowire array (NWA)-bulk thermoelectric power generator (TEG) with Cu contacts is improved by spin-on-doping (SOD). The Si NWAs used in this work are fabricated via metal assisted chemical etching (MACE) of 0.01–0.02 Ω cm resistivity n- and p-type bulk, converting ∼4% of the bulk thickness into NWs. The MACE process is adapted to ensure crystalline NWs. Current-voltage and Seebeck voltage-temperature measurements show that while SOD mainly influences the contact resistance in bulk, it influences both contact resistance and power factor in NWA-bulk based TEGs. According to our experiments, using Si NWAs in combination with SOD increases the output power by an order of 3 under the same heating power due to an increased power factor, decreased thermal conductivity of the NWA and reduced Si-Cu contact resistance.

  7. Nanoelectronic detection of triggered secretion of pro-inflammatory cytokines using CMOS compatible silicon nanowires.

    Science.gov (United States)

    Pui, Tze-Sian; Agarwal, Ajay; Ye, Feng; Huang, Yinxi; Chen, Peng

    2011-01-15

    Nanotechnology, such as nanoelectronic biosensors, is bringing new opportunities and tools to the studies of cell biology, clinical applications, and drug discovery. In this study, crystalline silicon nanowire based field-effect transistors fabricated using top-down approach were employed to parallelly detect pro-inflammatory cytokines in the complex biological fluids (cell culture medium and blood samples) with high specificity and femtomolar sensitivity. Using this technique, the dynamic secretion of TNF-alpha and IL6 was revealed during the immune response of macrophages and rats to the stimulation of bacteria endotoxin. This technique could provide a unique platform to examine the profile of complex immune responses for fundamental studies and diagnosis. PMID:20977978

  8. Interaction of nucleobases with silicon nanowires: A first-principles study

    Science.gov (United States)

    Zhong, Xiaoliang; Slough, William J.; Pandey, Ravindra; Friedrich, Craig

    2012-11-01

    The interaction between the nucleic acid bases - adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) - and a hydrogen-passivated silicon nanowire (SiNW) is investigated within the framework of density functional theory. The calculated binding energy of the nucleic acid bases with the SiNW shows the order: G > A≈C≈T≈U. This suggests that the interaction strength of a hydrogen passivated SiNW with the nucleic acid bases is nearly the same-G being an exception. The electronic structure of the nucleobase-SiNW complex is used to further characterize the nature of the interaction showing that it is likely electrostatic in nature.

  9. Investigation of drift effect on silicon nanowire field effect transistor based pH sensor

    Science.gov (United States)

    Kim, Sihyun; Kwon, Dae Woong; Lee, Ryoongbin; Kim, Dae Hwan; Park, Byung-Gook

    2016-06-01

    It is widely accepted that the operation mechanism of pH-sensitive ion sensitive field effect transistor (ISFET) can be divided into three categories; reaction of surface sites, chemical modification of insulator surface, and ionic diffusion into the bulk of insulator. The first mechanism is considered as the main operation mechanism of pH sensors due to fast response, while the others with relatively slow responses disturb accurate pH detection. In this study, the slow responses (often called drift effects) are investigated in silicon nanowire (SiNW) pH-sensitive ISFETs. Based on the dependence on the channel type of SiNW, liquid gate bias, and pH, it is clearly revealed that the drift of n-type SiNW results from H+ diffusion into the insulator whereas that of p-type SiNW is caused by chemical modification (hydration) of the insulator.

  10. Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

    International Nuclear Information System (INIS)

    Self-assembly of silicon nanowire (SiNW) arrays is studied using SF6/O2 plasma treatment. The self-assembly method can be applied to single- and poly-crystalline Si substrates. Plasma conditions can control the length and diameter of the SiNW arrays. Lower reflectance of the wire arrays over the wavelength range 200–1100 nm is obtained. The conducting transparent indium-tin-oxide (ITO) electrode can be fully coated on the self-assembled SiNW arrays by sputtering. The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating. An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments. (physics of gases, plasmas, and electric discharges)

  11. Modeling of a Silicon Nanowire pH Sensor with Nanoscale Side Gate Voltage

    Institute of Scientific and Technical Information of China (English)

    Alireza Kargar

    2009-01-01

    A silicon nanowire (Si-NW) sensor for pH detection is presented.The conductance of the device is analytically obtained,demonstrating that the conductance increases with decreasing oxide thickness.To calculate the electrical conductance of the sensor,the diffusion-drift model and nonlinear Poisson-Boltzmann equation are applied.To improve the conductance and sensitivity,a Si-NW sensor with nanoscale side gate voltage is offered and its characteristics are theoretically achieved.It is revealed that the conductance and sensor sensitivity can be enhanced by adding appropriate side gate voltages.This effect is compared to a similar fabricated structure in the literature,which has a wire with a rectangular cross section.Finally,the effect of NW length on sensor performance is investigated and an inverse relation between sensor sensitivity and NW length is achieved.

  12. A novel ultra steep dynamically reconfigurable electrostatically doped silicon nanowire Schottky Barrier FET

    Science.gov (United States)

    Singh, Sangeeta; Sinha, Ruchir; Kondekar, P. N.

    2016-05-01

    In this paper, an ultra steep, symmetric and dynamically configurable, electrostatically doped silicon nanowire Schottky FET (E-SiNW-SB-FET) based on dopant-free technology is investigated. It achieves the ultra steep sub-threshold slope (SS) due to the cumulative effect of weak impact-ionization induced positive feedback and electrostatic modulation of Schottky barrier heights at both source and drain terminals. It consists of axial nanowire heterostructure (silicide-intrinsic silicon-silicide) with three independent all-around gates, two gates are polarity control gates for dynamically reconfiguring the device polarity by modulating the effective Schottky barrier heights and a control gate switches the device ON and OFF. The most interesting features of the proposed structure are simplified fabrication process as the state-of-the-art for ion implantation and high thermal budget no more required for annealing. It is highly immune to process variations, doping control issues and random dopant fluctuations (RDF) and there are no mobility degradation issues related to high doping. A calibrated 3-D TCAD simulation results exhibit the SS of 2 mV/dec for n-type E-SiNW-SB-FET and 9 mV/dec for p-type E-SiNW-SB-FET for about five decades of current. Further, it resolves all the reliability related issues of IMOS as hot electron effects are no more limiting our device performance. It offers significant drive current of the order of 10-5-10-4 A and magnificently high ION/IOFF ratio of ∼108 along with the inherent advantages of symmetric device structure for its circuit realization.

  13. Evaluation of Seebeck coefficients in n- and p-type silicon nanowires fabricated by complementary metal–oxide–semiconductor technology

    International Nuclear Information System (INIS)

    Silicon-based thermoelectric nanowires were fabricated by using complementary metal–oxide–semiconductor (CMOS) technology. 50 nm width n- and p-type silicon nanowires (SiNWs) were manufactured using a conventional photolithography method on 8 inch silicon wafer. For the evaluation of the Seebeck coefficients of the silicon nanowires, heater and temperature sensor embedded test patterns were fabricated. Moreover, for the elimination of electrical and thermal contact resistance issues, the SiNWs, heater and temperature sensors were fabricated monolithically using a CMOS process. For validation of the temperature measurement by an electrical method, scanning thermal microscopy analysis was carried out. The highest Seebeck coefficients were − 169.97 μV K−1 and 152.82 μV K−1 and the highest power factors were 2.77 mW m−1 K−2 and 0.65 mW m−1 K−2 for n- and p-type SiNWs, respectively, in the temperature range from 200 to 300 K. The larger power factor value for n-type SiNW was due to the higher electrical conductivity. The total Seebeck coefficient and total power factor for the n- and p-leg unit device were 157.66 μV K−1 and 9.30 mW m−1 K−2 at 300 K, respectively. (paper)

  14. Fabrication of silicon carbide nanowires/carbon nanotubes heterojunction arrays by high-flux Si ion implantation.

    Science.gov (United States)

    Liu, Huaping; Cheng, Guo-An; Liang, Changlin; Zheng, Ruiting

    2008-06-18

    An array of silicon carbide nanowire (SiCNW)-carbon nanotube (CNT) heterojunctions was fabricated by high-flux Si ion implantation into a multi-walled carbon nanotube (MWCNT) array with a metal vapor vacuum arc (MEVVA) ion source. Under Si irradiation, the top part of a CNT array was gradually transformed into an amorphous nanowire array with increasing Si dose while the bottom part still remained a CNT structure. X-ray photoelectron spectroscopy (XPS) analysis shows that the SiC compound was produced in the nanowire part even at the lower Si dose of 5 × 10(16) ions cm(-2), and the SiC amount increased with increasing the Si dose. Therefore, the fabrication of a SiCNW-CNT heterojunction array with the MEVVA technique has been successfully demonstrated. The corresponding formation mechanism of SiCNWs was proposed. PMID:21825818

  15. Printable Bioelectronics To Investigate Functional Biological Interfaces.

    Science.gov (United States)

    Manoli, Kyriaki; Magliulo, Maria; Mulla, Mohammad Yusuf; Singh, Mandeep; Sabbatini, Luigia; Palazzo, Gerardo; Torsi, Luisa

    2015-10-19

    Thin-film transistors can be used as high-performance bioelectronic devices to accomplish tasks such as sensing or controlling the release of biological species as well as transducing the electrical activity of cells or even organs, such as the brain. Organic, graphene, or zinc oxide are used as convenient printable semiconducting layers and can lead to high-performance low-cost bioelectronic sensing devices that are potentially very useful for point-of-care applications. Among others, electrolyte-gated transistors are of interest as they can be operated as capacitance-modulated devices, because of the high capacitance of their charge double layers. Specifically, it is the capacitance of the biolayer, being lowest in a series of capacitors, which controls the output current of the device. Such an occurrence allows for extremely high sensitivity towards very weak interactions. All the aspects governing these processes are reviewed here. PMID:26420480

  16. Organic Bioelectronic Tools for Biomedical Applications

    OpenAIRE

    Susanne Löffler; Ben Libberton; Agneta Richter-Dahlfors

    2015-01-01

    Organic bioelectronics forms the basis of conductive polymer tools with great potential for application in biomedical science and medicine. It is a rapidly growing field of both academic and industrial interest since conductive polymers bridge the gap between electronics and biology by being electronically and ionically conductive. This feature can be employed in numerous ways by choosing the right polyelectrolyte system and tuning its properties towards the intended application. This review ...

  17. Switchable bioelectronics on graphene interface (Presentation Recording)

    Science.gov (United States)

    Parlak, Onur; Tiwari, Ashutosh; Turner, Anthony P. F.

    2015-08-01

    Smart and flexible bioelectronics on graphene have emerged as a new frontier in the field of biosensors and bioelectronics. Graphene has begun to be seen as an ideal signal transducer and a promising alternative for the production of low-cost bioelectronic devices.1-2 However, biological systems used in these devices suffer from a lack of control and regulation. There is an obvious need to develop "switchable" and "smart" interfaces for both fundamental and applied studies. Here, we report the fabrication of a stimuli-responsive graphene interface, which is used to regulate biomolecular reactions. The present study aims to address the design and development of a novel auto-switchable graphene bio-interface that is capable of positively responding, by creating smart nanoarchitectures. By changing the external conditions such as temperature, light and pH of the medium, we acheived control of the biochemical interactions. In the negative mode, access of an associated enzyme to its substrate is largely restricted, resulting in a decrease in the diffusion of reactants and the consequent activity of the system. In contrast, the biosubstrate could freely access the enzyme facilitating bioelectrocatalysis in a positive response. Using electrochemical techniques, we demonstrated that interfacial bio-electrochemical properties can be tuned by modest changes in conditions. Such an ability to independently regulate the behaviour of the interface has important implications for the design of novel bioreactors, biofuel cells and biosensors with inbuilt self-control features.

  18. Near-infrared quarter-waveplate with near-unity polarization conversion efficiency based on silicon nanowire array.

    Science.gov (United States)

    Dai, Yanmeng; Cai, Hongbing; Ding, Huaiyi; Ning, Zhen; Pan, Nan; Zhu, Hong; Shi, Qinwei; Wang, Xiaoping

    2015-04-01

    Metasurfaces made of subwavelength resonators can modify the wave front of light within the thickness much less than free space wavelength, showing great promises in integrated optics. In this paper, we theoretically show that electric and magnetic resonances supported simultaneously by a subwavelength nanowire with high refractive-index can be utilized to design metasurfaces with near-unity transmittance. Taking silicon nanowire for instance, we design numerically a near-infrared quarter-waveplate with high transmittance using a subwavelength nanowire array. The operation bandwidth of the waveplate is 0.14 μm around the center wavelength of 1.71 μm. The waveplate can convert a 45° linearly polarized incident light to circularly polarized light with conversion efficiency ranging from 94% to 98% over the operation band. The performance of quarter waveplate can in principle be tuned and improved through optimizing the parameters of nanowire arrays. Its compatibility to microelectronic technologies opens up a distinct possibility to integrate nanophotonics into the current silicon-based electronic devices. PMID:25968730

  19. A high performance three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection

    Science.gov (United States)

    Xu, Chenlong; Song, Zhiqian; Xiang, Qun; Jin, Jian; Feng, Xinjian

    2016-03-01

    We describe here a high performance oxygen-rich three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection. We demonstrate that its linear detection upper limit is 30 mM, more than 15 times higher than that can be obtained on the normal enzyme-electrode. Notably, the three-phase enzyme electrode output is insensitive to the significant oxygen level fluctuation in analyte solution.We describe here a high performance oxygen-rich three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection. We demonstrate that its linear detection upper limit is 30 mM, more than 15 times higher than that can be obtained on the normal enzyme-electrode. Notably, the three-phase enzyme electrode output is insensitive to the significant oxygen level fluctuation in analyte solution. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08370b

  20. Catalytic activity of silicon nanowires decorated with silver and copper nanoparticles

    Science.gov (United States)

    Amdouni, Sonia; Coffinier, Yannick; Szunerits, Sabine; Zaïbi, Mohammed Ali; Oueslati, Meherzi; Boukherroub, Rabah

    2016-01-01

    The paper reports on the elaboration of silicon nanowires decorated with silver (SiNWs-Ag NPs) or copper (SiNWs-Cu NPs) nanoparticles and the investigation of their catalytic properties for the reduction of 4-nitrophenol to 4-aminophenol. The SiNW arrays were produced through chemical etching of crystalline silicon in HF/AgNO3 aqueous solution. The metal nanoparticles were deposited on the SiNW substrates through chemical bath immersion in a metal salt/hydrofluoric acid aqueous solution. The SiNWs decorated with Ag NPs and Cu NPs were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). The catalytic activity of the SiNWs loaded with metal nanoparticles was evaluated for the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride (NaBH4). The substrates exhibited good catalytic performance toward nitrophenol with a full reduction in less than 30 s for the SiNWs-Cu NPs.

  1. The role of silane gas flow rate on PECVD-assisted fabrication of silicon nanowires

    Science.gov (United States)

    Hamidinezhad, Habib; Ashkarran, Ali Akbar; Abdul-Malek, Zulkurnain

    2016-03-01

    Silicon (Si) core-shell nanowires (NWs) were successfully prepared by very high frequency plasma-enhanced chemical vapor deposition technique, and the effect of silane (SiH4) gas flow rates on physicochemical properties of silicon NWs was investigated. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize SiNWs. Structural properties and morphology of NWs were studied as a function of SiH4 gas flow rate. Microscopic analysis revealed the formation of SiNWs with average tip and stem diameters ranging from 18 to 30 and 21 to 67 nm, respectively. Furthermore, the average length of Si NWs calculated based on the FESEM images was about 300-1800 nm. We have found that the growth of SiNWs increased with increasing in SiH4 gas flow rate. XRD, Raman spectra in addition to high-resolution TEM, verified the formation of crystalline SiNWs. A possible growth mechanism was suggested based on our observations.

  2. Dense nanoimprinted silicon nanowire arrays with passivated axial p-i-n junctions for photovoltaic applications

    Science.gov (United States)

    Zhang, Peng; Liu, Pei; Siontas, Stylianos; Zaslavsky, A.; Pacifici, D.; Ha, Jong-Yoon; Krylyuk, S.; Davydov, A. V.

    2015-03-01

    We report on the fabrication and photovoltaic characteristics of vertical arrays of silicon axial p-i-n junction nanowire (NW) solar cells grown by vapor-liquid-solid (VLS) epitaxy. NW surface passivation with silicon dioxide shell is shown to enhance carrier recombination time, open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF). The photovoltaic performance of passivated individual NW and NW arrays was compared under 532 nm laser illumination with power density of ˜10 W/cm2. Higher values of VOC and FF in the NW arrays are explained by enhanced light trapping. In order to verify the effect of NW density on light absorption and hence on the photovoltaic performance of NW arrays, dense Si NW arrays were fabricated using nanoimprint lithography to periodically arrange the gold seed particles prior to epitaxial growth. Compared to sparse NW arrays fabricated using VLS growth from randomly distributed gold seeds, the nanoimprinted NW array solar cells show a greatly increased peak external quantum efficiency of ˜8% and internal quantum efficiency of ˜90% in the visible spectral range. Three-dimensional finite-difference time-domain simulations of Si NW periodic arrays with varying pitch (P) confirm the importance of high NW density. Specifically, due to diffractive scattering and light trapping, absorption efficiency close to 100% in the 400-650 nm spectral range is calculated for a Si NW array with P = 250 nm, significantly outperforming a blanket Si film of the same thickness.

  3. Processing-Induced Electrically Active Defects in Black Silicon Nanowire Devices.

    Science.gov (United States)

    Carapezzi, Stefania; Castaldini, Antonio; Mancarella, Fulvio; Poggi, Antonella; Cavallini, Anna

    2016-04-27

    Silicon nanowires (Si NWs) are widely investigated nowadays for implementation in advanced energy conversion and storage devices, as well as many other possible applications. Black silicon (BSi)-NWs are dry etched NWs that merge the advantages related to low-dimensionality with the special industrial appeal connected to deep reactive ion etching (RIE). In fact, RIE is a well established technique in microelectronics manufacturing. However, RIE processing could affect the electrical properties of BSi-NWs by introducing deep states into their forbidden gap. This work applies deep level transient spectroscopy (DLTS) to identify electrically active deep levels and the associated defects in dry etched Si NW arrays. Besides, the successful fitting of DLTS spectra of BSi-NWs-based Schottky barrier diodes is an experimental confirmation that the same theoretical framework of dynamic electronic behavior of deep levels applies in bulk as well as in low dimensional structures like NWs, when quantum confinement conditions do not occur. This has been validated for deep levels associated with simple pointlike defects as well as for deep levels associated with defects with richer structures, whose dynamic electronic behavior implies a more complex picture. PMID:26979506

  4. Synthesis, characterization and application of electroless metal assisted silicon nanowire arrays

    Science.gov (United States)

    Sahoo, Sumanta Kumar; Marikani, Arumugam

    2015-12-01

    Vertically aligned silicon nanowire arrays (SiNWs) have been synthesized by electroless metal deposition process. The fabricated SiNWs have an average diameter of 75 nm and 3.5-4.0 μm length, as confirmed from scanning electron microscopy. A characteristic asymmetric peak broadening at 520 cm-1 from Raman spectroscopy was obtained for the SiNWs as compared to the bulk silicon crystal due to phonon confinement. The as-prepared SiNWs exhibit good electron field-emission properties with turn-on field of about 8.26 V μm-1 at a current density of 4.9 μA cm-2. The SiNWs was functionalized by coating with a thin gold metallic film for 60 s, and then used as bio-probe for the detection of bovine serum albumin (BSA) protein molecules. From the linear sweep voltammetry analysis, the Au coated SiNWs, exhibit linear response to the BSA analyte with increase in concentration. The minimum detection limit of the protein molecule was calculated of about 1.16 μM by the as-synthesized SiNWs probe.

  5. Nano-Scale Tensile Testing and Sample Preparation Techniques for Silicon Nanowires

    Science.gov (United States)

    Fujii, Tatsuya; Sudoh, Koichi; Sakakihara, Shouichi; Naito, Muneyuki; Inoue, Shozo; Namazu, Takahiro

    2013-11-01

    In this paper, we describe an experimental technique to achieve a highly reliable characterization of the mechanical properties of silicon (Si) nanowires (NWs). A reusable on-chip Si device consisting of comb-drive electrostatic actuator for generating tensile force and capacitive sensors for measuring tensile force and displacement was designed and developed for quasi-static tensile test of Si NWs. The combination of focused ion beam (FIB) fabrication, FIB-assisted chemical vapor deposition, and probe manipulation enabled us to directly fabricate the NWs on the device. This sampling technique led to high yielding percentage of nano-scale tensile testing. The NWs were made from 200-nm-thick Si membranes that were produced by using silicon-on-nothing membrane fabrication technique. Several Si NWs were annealed at 700 °C in ultrahigh vacuum (UHV) for 5 min in order to examine the influence of annealing on the mechanical characteristics. The mean Young's modulus for nonannealed NWs was 129.1+/-10.1 GPa. After UHV annealing, the mean value was improved to be 168.1+/-1.3 GPa, comparable to the ideal value for Si(001)[110]. The annealing process gave rise to improving the Young's modulus, whereas it degraded the strength. Transmission electron microscopy suggested that recrystallization and gallium nanoclusters formation by annealing would have changed the mechanical characteristics.

  6. Heterostructures of germanium nanowires and germanium-silicon oxide nanotubes and growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J Q; Chim, W K [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576 (Singapore); Chiam, S Y; Wong, L M; Wang, S J, E-mail: elecwk@nus.edu.s [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, 117602 (Singapore)

    2009-10-21

    We report on a method to fabricate one-dimensional heterostructures of germanium nanowires (GeNWs) and germanium-silicon oxide nanotubes (GeSiO{sub x}NTs). The synthesis of the wire-tube heterostructures is carried out using a simple furnace set-up with germanium tetraiodide and germanium powders as growth precursors, gold-dotted silicon wafers as substrates and by controlling the temperature ramp rate/sequence of the growth precursors. Two types of wire-tube heterostructures resulting from distinct growth mechanisms are obtained. The type-1 heterostructure consists of a GeNW, grown via a gold-catalyzed vapour-liquid-solid process, at the lower end and a GeSiO{sub x}NT at the upper end. In contrast, the type-2 heterostructure is made up of a solid wire at the upper end and a hollow tube at the lower end. The solid wire portion of the type-2 heterostructure is formed through an oxide-assisted growth process.

  7. Heterostructures of germanium nanowires and germanium-silicon oxide nanotubes and growth mechanisms

    International Nuclear Information System (INIS)

    We report on a method to fabricate one-dimensional heterostructures of germanium nanowires (GeNWs) and germanium-silicon oxide nanotubes (GeSiOxNTs). The synthesis of the wire-tube heterostructures is carried out using a simple furnace set-up with germanium tetraiodide and germanium powders as growth precursors, gold-dotted silicon wafers as substrates and by controlling the temperature ramp rate/sequence of the growth precursors. Two types of wire-tube heterostructures resulting from distinct growth mechanisms are obtained. The type-1 heterostructure consists of a GeNW, grown via a gold-catalyzed vapour-liquid-solid process, at the lower end and a GeSiOxNT at the upper end. In contrast, the type-2 heterostructure is made up of a solid wire at the upper end and a hollow tube at the lower end. The solid wire portion of the type-2 heterostructure is formed through an oxide-assisted growth process.

  8. Rice-straw-like structure of silicon nanowire arrays for a hydrogen gas sensor

    International Nuclear Information System (INIS)

    A rice-straw-like silicon nanowire (SiNW) array was developed for hydrogen gas sensing applications. The straight-aligned SiNW array sensor was first fabricated by the metal-assisted electroless etching (MAEE) technique. Rice-straw-like SiNW arrays were formed using a repeated MAEE technique. Hydrogen sensing characteristics were measured for gas concentrations from 20 to 1000 ppm at room temperature. The rice-straw-like SiNW-array-based hydrogen gas sensor performed with low noise and a high response (232.5%) for 1000 ppm hydrogen gas. It was found that the rice-straw-like SiNW-array hydrogen gas sensor had a much better response (approximately 2.5 times) than the straight-aligned SiNW-array sensor. The rice-straw-like SiNW-array structure effectively increased the surface area and the concentration of silicon oxide, which provided additional binding sites for gas molecules. Thus, the rice-straw-like SiNW-array-based hydrogen gas sensor possessed good sensing properties and has the potential for mass production of sensing devices. (paper)

  9. Growth of silicon nanowires on ZnO thin film stimulated by VLS and PECVD processes for photovoltaic applications

    Czech Academy of Sciences Publication Activity Database

    Pham, T.T.; Le, V.T.H.; Cu, T.S.; Stuchlíková, The-Ha; Hruška, Karel; Ledinský, Martin; Stuchlík, Jiří

    Ho Chi Minh City: Laboratory for Nanotechnology, VNU, 2013, s. 411-414. [IWNA 2013 - 4th International Workshop on Nanotechnology and Application. Vung Tau (VN), 14.11.2013-16.11.2013] R&D Projects: GA MŠk LH12236 Institutional support: RVO:68378271 Keywords : silicon nanowires (Si-NWs) * PECVD * ZnO * VLS process * Sn Subject RIV: BM - Solid Matter Physics ; Magnetism

  10. High Throughput Nanofabrication of Silicon Nanowire and Carbon Nanotube Tips on AFM Probes by Stencil-Deposited Catalysts

    DEFF Research Database (Denmark)

    Engstrøm, Daniel Southcott; Savu, Veronica; Zhu, Xueni;

    2011-01-01

    A new and versatile technique for the wafer scale nanofabrication of silicon nanowire (SiNW) and multiwalled carbon nanotube (MWNT) tips on atomic force microscope (AFM) probes is presented. Catalyst material for the SiNW and MWNT growth was deposited on prefabricated AFM probes using aligned wafer...... demonstrated a significantly better performance than commercial high aspect ratio tips. Our method demonstrates a reliable and cost-efficient route toward wafer scale manufacturing of SiNW and MWNT AFM probes....

  11. Texturing of the Silicon Substrate with Nanopores and Si Nanowires for Anti-reflecting Surfaces of Solar Cells

    Directory of Open Access Journals (Sweden)

    A.A. Druzhinin

    2015-06-01

    Full Text Available The paper presents the prospects of obtaining a functional multi-layer anti-reflecting coating of the front surface of solar cells by texturing the surface of the silicon by electrochemical etching. The physical model of the "Black Si" coating with discrete inhomogeneity of the refractive index and technological aspects of producing of "Black Si" functional anti-reflecting coatings were presented. The investigation results of the spectral characteristics of the obtained multilayer multiporous "Black Si" coatings for silicon solar cells made by electrochemical etching are presented. The possibility of creating the texture on a silicon wafer surface using silicon nanowires and ordered nanopores obtained by metal-assisted chemical etching was shown.

  12. Fluorinion transfer in silver-assisted chemical etching for silicon nanowires arrays

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Tianyu; Xu, Youlong, E-mail: ylxu@mail.xjtu.edu.cn; Zhang, Zhengwei; Mao, Shengchun

    2015-08-30

    Graphical abstract: - Highlights: • How Ag transfers F{sup −} to the adjacent Si atom was investigated and deduced by DFT at atomic scale. • Three-electrode CV tests proved the transferring function of Ag in the etching reaction. • Uniform SiNWAs were fabricated on unpolished silicon wafers with KOH pretreatment. - Abstract: Uniform silicon nanowires arrays (SiNWAs) were fabricated on unpolished rough silicon wafers through KOH pretreatment followed by silver-assisted chemical etching (SACE). Density functional theory (DFT) calculations were used to investigate the function of silver (Ag) at atomic scale in the etching process. Among three adsorption sites of Ag atom on Si(1 0 0) surface, Ag(T4) above the fourth-layer surface Si atoms could transfer fluorinion (F{sup −}) to adjacent Si successfully due to its stronger electrostatic attraction force between Ag(T4) and F{sup −}, smaller azimuth angle of F−Ag(T4)−Si, shorter bond length of F−Si compared with F−Ag. As F{sup −} was transferred to adjacent Si by Ag(T4) one by one, the Si got away from the wafer in the form of SiF{sub 4} when it bonded with enough F{sup −} while Ag(T4) was still attached onto the Si wafer ready for next transfer. Cyclic voltammetry tests confirmed that Ag can improve the etching rate by transferring F{sup −} to Si.

  13. "In situ" hard mask materials: a new methodology for creation of vertical silicon nanopillar and nanowire arrays.

    Science.gov (United States)

    Ghoshal, Tandra; Senthamaraikannan, Ramsankar; Shaw, Matthew T; Holmes, Justin D; Morris, Michael A

    2012-12-21

    A novel, simple and in situ hard mask technology that can be used to develop high aspect ratio silicon nanopillar and nanowire features on a substrate surface is demonstrated. The technique combines a block copolymer inclusion method that generates nanodot arrays on substrate and an inductively coupled plasma (ICP) etch processing step to fabricate Si nanopillar and nanowire arrays. Iron oxide was found to be an excellent resistant mask over silicon under the selected etching conditions. Features of a very high aspect ratio can be created by this method. The nanopillars have uniform diameter and smooth sidewalls throughout their entire length. The diameter (15-27 nm) and length of the nanopillars can be tuned easily. Different spectroscopic and microscopic techniques were used to examine the morphology and size, surface composition and crystallinity of the resultant patterns. The methodology developed may have important technological applications and provide an inexpensive manufacturing route to nanodimensioned topographical patterns. The high aspect ratio of the features may have importance in the area of photonics and the photoluminescence properties are found to be similar to those of surface-oxidized silicon nanocrystals and porous silicon. PMID:23138854

  14. Structural and photoluminescent properties of nanowires formed by the metal-assisted chemical etching of monocrystalline silicon with different doping level

    International Nuclear Information System (INIS)

    Silicon-nanowire layers grown by the metal-assisted chemical etching of (100)-oriented p-type monocrystalline silicon substrates with a resistivity of 10 and 0.001 Ω · cm are studied by electron microscopy, Raman scattering, and photoluminescence measurements. It is established that nanowires grown on lightly doped substrates are structurally nonporous and formed as crystalline cores covered by nanocrystals 3–5 nm in dimensions. Nanowires grown on heavily doped substrates are structurally porous and contain both small nanocrystals and coarser crystallites with equilibrium charge carriers that influence interband radiative recombination. It is found that the photoluminescence intensity of nanowires in the spectral range 1.3–2.0 eV depends on the presence of molecular oxygen

  15. Structural and photoluminescent properties of nanowires formed by the metal-assisted chemical etching of monocrystalline silicon with different doping level

    Energy Technology Data Exchange (ETDEWEB)

    Georgobiani, V. A., E-mail: v.georgobiani@gmail.com; Gonchar, K. A.; Osminkina, L. A.; Timoshenko, V. Yu. [Lomonosov Moscow State University, Faculty of Physics (Russian Federation)

    2015-08-15

    Silicon-nanowire layers grown by the metal-assisted chemical etching of (100)-oriented p-type monocrystalline silicon substrates with a resistivity of 10 and 0.001 Ω · cm are studied by electron microscopy, Raman scattering, and photoluminescence measurements. It is established that nanowires grown on lightly doped substrates are structurally nonporous and formed as crystalline cores covered by nanocrystals 3–5 nm in dimensions. Nanowires grown on heavily doped substrates are structurally porous and contain both small nanocrystals and coarser crystallites with equilibrium charge carriers that influence interband radiative recombination. It is found that the photoluminescence intensity of nanowires in the spectral range 1.3–2.0 eV depends on the presence of molecular oxygen.

  16. Multi-Wire Tri-Gate Silicon Nanowires Reaching Milli-pH Unit Resolution in One Micron Square Footprint

    Directory of Open Access Journals (Sweden)

    Enrico Accastelli

    2016-03-01

    Full Text Available The signal-to-noise ratio of planar ISFET pH sensors deteriorates when reducing the area occupied by the device, thus hampering the scalability of on-chip analytical systems which detect the DNA polymerase through pH measurements. Top-down nano-sized tri-gate transistors, such as silicon nanowires, are designed for high performance solid-state circuits thanks to their superior properties of voltage-to-current transduction, which can be advantageously exploited for pH sensing. A systematic study is carried out on rectangular-shaped nanowires developed in a complementary metal-oxide-semiconductor (CMOS-compatible technology, showing that reducing the width of the devices below a few hundreds of nanometers leads to higher charge sensitivity. Moreover, devices composed of several wires in parallel further increase the exposed surface per unit footprint area, thus maximizing the signal-to-noise ratio. This technology allows a sub milli-pH unit resolution with a sensor footprint of about 1 µm2, exceeding the performance of previously reported studies on silicon nanowires by two orders of magnitude.

  17. Multi-Wire Tri-Gate Silicon Nanowires Reaching Milli-pH Unit Resolution in One Micron Square Footprint.

    Science.gov (United States)

    Accastelli, Enrico; Scarbolo, Paolo; Ernst, Thomas; Palestri, Pierpaolo; Selmi, Luca; Guiducci, Carlotta

    2016-03-01

    The signal-to-noise ratio of planar ISFET pH sensors deteriorates when reducing the area occupied by the device, thus hampering the scalability of on-chip analytical systems which detect the DNA polymerase through pH measurements. Top-down nano-sized tri-gate transistors, such as silicon nanowires, are designed for high performance solid-state circuits thanks to their superior properties of voltage-to-current transduction, which can be advantageously exploited for pH sensing. A systematic study is carried out on rectangular-shaped nanowires developed in a complementary metal-oxide-semiconductor (CMOS)-compatible technology, showing that reducing the width of the devices below a few hundreds of nanometers leads to higher charge sensitivity. Moreover, devices composed of several wires in parallel further increase the exposed surface per unit footprint area, thus maximizing the signal-to-noise ratio. This technology allows a sub milli-pH unit resolution with a sensor footprint of about 1 µm², exceeding the performance of previously reported studies on silicon nanowires by two orders of magnitude. PMID:26999232

  18. Realization of high performance silicon nanowire based solar cells with large size

    International Nuclear Information System (INIS)

    We report the realization of high performance silicon nanowire (SiNW) based solar cells with a conversion efficiency of 17.11% and a large size of 125 × 125 mm2. The key factor for success lies in an efficient approach of dielectric passivation to greatly enhance the electrical properties while keeping the advantage of excellent light trapping of the SiNW structure. The suppression of carrier recombination has been demonstrated through the combination of the SiO2/SiNx stack, which exhibits a good passivation effect on heavily doped SiNWs via reducing both the Shockley–Read–Hall recombination and near surface Auger recombination. We have examined in detail the effects of different passivations and SiNW lengths on the effective minority carrier lifetime, reflectance and carrier recombination characteristics, as well as cell performance. The proposed passivation techniques can be easily adapted to conventional industrial manufacturing processes, providing a potential prospect of SiNW based solar cells in mass production. (paper)

  19. Characterization of a silicon nanowire-based cantilever air-flow sensor

    International Nuclear Information System (INIS)

    Silicon nanowire (SiNW)-based cantilever flow sensors with three different cantilever sizes (10 × 50, 20 × 90 and 40 × 100 µm2) and various SiNW lengths (2, 5 and 10 µm) have been designed for air velocity sensing. The total device thickness is around 3 µm, which consists of the bottom SiO2 layer (0.5 µm) and the top SiNx layer (2.5 µm). In addition, the SiNx layer is used to compensate the initial stress and also enhance the device immunity to air-flow-induced vibrations significantly. To experience the maximum strain induced by the air flow, SiNWs are embedded at the clamp point where the cantilever is anchored to the substrate. Taking advantage of the superior properties of SiNWs, the reported flow sensor shows outstanding air-flow-sensing capability in terms of sensitivity, linearity and hysteresis. With only a supply voltage of 0.1 V and the high initial resistance of the piezoresistive SiNWs, significant energy saving is reached in contrast to the thermal-based flow sensors as well as other recently reported piezoresistive designs. Last but not least, the significant size reduction of our device demonstrates the great scalability of SiNW-based flow sensors. (paper)

  20. Silicon nanowire based biosensing platform for electrochemical sensing of Mebendazole drug activity on breast cancer cells.

    Science.gov (United States)

    Shashaani, Hani; Faramarzpour, Mahsa; Hassanpour, Morteza; Namdar, Nasser; Alikhani, Alireza; Abdolahad, Mohammad

    2016-11-15

    Electrochemical approaches have played crucial roles in bio sensing because of their Potential in achieving sensitive, specific and low-cost detection of biomolecules and other bio evidences. Engineering the electrochemical sensing interface with nanomaterials tends to new generations of label-free biosensors with improved performances in terms of sensitive area and response signals. Here we applied Silicon Nanowire (SiNW) array electrodes (in an integrated architecture of working, counter and reference electrodes) grown by low pressure chemical vapor deposition (LPCVD) system with VLS procedure to electrochemically diagnose the presence of breast cancer cells as well as their response to anticancer drugs. Mebendazole (MBZ), has been used as antitubulin drug. It perturbs the anodic/cathodic response of the cell covered biosensor by releasing Cytochrome C in cytoplasm. Reduction of cytochrome C would change the ionic state of the cells monitored by SiNW biosensor. By applying well direct bioelectrical contacts with cancer cells, SiNWs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Our device detected the trace of MBZ drugs (with the concentration of 2nM) on electrochemical activity MCF-7 cells. Also, experimented biological analysis such as confocal and Flowcytometry assays confirmed the electrochemical results. PMID:27196254

  1. Decoration of silicon nanowires with silver nanoparticles for ultrasensitive surface enhanced Raman scattering

    Science.gov (United States)

    D’Andrea, Cristiano; Lo Faro, Maria J.; Bertino, Giulia; Ossi, Paolo M.; Neri, Fortunato; Trusso, Sebastiano; Musumeci, Paolo; Galli, Matteo; Cioffi, Nicola; Irrera, Alessia; Priolo, Francesco; Fazio, Barbara

    2016-09-01

    Silicon nanowires (Si NWs), produced by the chemical etching technique, were decorated with silver nanoparticles (NPs) produced at room temperature by the pulsed laser deposition (PLD) technique. Silver NPs were obtained by means of nanosecond pulsed laser ablation of a target in the presence of a controlled Ar atmosphere. Two different laser pulse numbers and Si NWs having different lengths were used to change the NP number density on the Si NW surface. The resulting Ag NP morphologies were studied by scanning electron microscopy imaging. The results show that this industrially compatible technological approach allows the coverage of the Si NW walls with Ag NPs with a strong control of the NP size distribution and spatial arrangement. The obtained Ag NP decorated Si NWs are free from chemicals contamination and there is no need of post deposition high temperature processes. The optical properties of Si NW arrays were investigated by reflectance spectroscopy that showed the presence of a plasmon related absorption peak, whose position and width is dependent on the Ag NP surface morphology. Coupling the huge surface-to-volume ratio of Si NW arrays with the plasmonic properties of silver nanoparticles resulted in a 3D structure suitable for very sensitive surface enhanced Raman scattering (SERS) applications, as demonstrated by the detection of Rhodamine 6G in aqueous solution at a concentration level of 10‑8 M.

  2. Carrier density distribution in silicon nanowires investigated by scanning thermal microscopy and Kelvin probe force microscopy.

    Science.gov (United States)

    Wielgoszewski, Grzegorz; Pałetko, Piotr; Tomaszewski, Daniel; Zaborowski, Michał; Jóźwiak, Grzegorz; Kopiec, Daniel; Gotszalk, Teodor; Grabiec, Piotr

    2015-12-01

    The use of scanning thermal microscopy (SThM) and Kelvin probe force microscopy (KPFM) to investigate silicon nanowires (SiNWs) is presented. SThM allows imaging of temperature distribution at the nanoscale, while KPFM images the potential distribution with AFM-related ultra-high spatial resolution. Both techniques are therefore suitable for imaging the resistance distribution. We show results of experimental examination of dual channel n-type SiNWs with channel width of 100 nm, while the channel was open and current was flowing through the SiNW. To investigate the carrier distribution in the SiNWs we performed SThM and KPFM scans. The SThM results showed non-symmetrical temperature distribution along the SiNWs with temperature maximum shifted towards the contact of higher potential. These results corresponded to those expressed by the distribution of potential gradient along the SiNWs, obtained using the KPFM method. Consequently, non-uniform distribution of resistance was shown, being a result of non-uniform carrier density distribution in the structure and showing the pinch-off effect. Last but not least, the results were also compared with results of finite-element method modeling. PMID:26381074

  3. Cycling strategies for optimizing silicon nanowires performance as negative electrode for lithium battery

    International Nuclear Information System (INIS)

    Highlights: • Original cycling conditions combining cut-off potential and involved capacity • Influence of capacity limitation is investigated for lithiation and delithiation • Importance of a reduced delithiation cut-off voltage is demonstrated • At C/5 rate, 1800 cycles are reached without electrode or electrolyte optimization • A 1 C rate, 2000 cycles are reached with electrolyte containing VC additive - Abstract: The cycling conditions of silicon nanowires anode are investigated and a set of conditions is proposed in order to improve the cycle life of these electrodes, without any structure or surface optimization. Limitation of lithiation or delithiation to an intermediate value of 900 mAh g−1 allows to perform up to 1850 cycles at C/5 rate, which represents a significant increase of the electrode cycle life compared to that observed for standard cycling. This behavior is still attractive at higher current rate. At 1 C rate, it is proved that combining the lithiation-limited cycling with an upper cut-off voltage of 0.8 V improves the capacity retention by a factor 2. When using these optimized conditions, combined with a simple adding of fluoroethylene carbonate or vinylene carbonate in the electrolyte, a compact solid electrolyte interphase is formed upon cycling and an exceptional capacity retention is observed, reaching respectively 1500 and more than 2000 cycles

  4. Mode hybridization and conversion in silicon-on-insulator nanowires with angled sidewalls.

    Science.gov (United States)

    Dai, Daoxin; Zhang, Ming

    2015-12-14

    The mode property and light propagation in a tapered silicon-on-insulator (SOI) nanowire with angled sidewalls is analyzed. Mode hybridization is observed and mode conversion between the TM fundamental mode and higher-order TE modes happens when light propagates in a waveguide taper which is used very often in the design of photonic integrated devices. This mode conversion ratio is possible to be very high (even close to 100%) when the taper is long enough to be adiabatic, which might be useful for some applications of multimode photonics. When the mode conversion is undesired to avoid any excess loss as well as crosstalk for photonic integrated circuits, one can depress the mode conversion by compensating the vertical asymmetry in the way of reducing the sidewall angle or introducing an optimal refractive index for the upper-cladding. It is also possible to eliminate the undesired mode conversion almost and improve the desired mode conversion greatly by introducing an abrupt junction connecting two sections with different widths to jump over the mode hybridization region. PMID:26699034

  5. Growth rate model and doping metrology by atom probe tomography in silicon nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.H.; Larde, R.; Cadel, E.; Pareige, P. [Groupe de Physique des Materiaux, Universite et INSA de Rouen, UMR CNRS 6634, Av. de l' Universite, BP 12, 76801 Saint Etienne du Rouvray (France); Xu, T.; Grandidier, B.; Nys, J.P.; Stievenard, D. [Institut d' Electronique, de Microelectronique et de Nanotechnologie, UMR CNRS 8520, Departement ISEN, 41 bd Vauban, 59046 Lille Cedex (France)

    2011-03-15

    Silicon nanowires (SiNWs) with different surface number density are fabricated using Chemical Vapor Deposition (CVD) method by controlling the catalyst droplet number density with in-situ evaporation. For comparison, another type of SiNWs is fabricated by Molecular Beam Epitaxy (MBE) method. To study these two types of SiNWs a general growth rate model is presented. The fit curves from this model are consistent with our experimental data. In both growing conditions the SiNW growth rate as a function of their diameter are compared and discussed. The p-type SiNWs have also been prepared by adding diborane into precursor. The doping metrology in an individual SiNW is realized by laser assisted Atom Probe Tomography (APT). We have shown that the doping atoms (e.g. B) can incorporate into SiNW and an accurate quantification can be given (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Electrostatic actuated strain engineering in monolithically integrated VLS grown silicon nanowires

    Science.gov (United States)

    Wagesreither, Stefan; Bertagnolli, Emmerich; Kawase, Shinya; Isono, Yoshitada; Lugstein, Alois

    2014-11-01

    In this paper we demonstrate the fabrication and application of an electrostatic actuated tensile straining test (EATEST) device enabling strain engineering in individual suspended nanowires (NWs). Contrary to previously reported approaches, this special setup guarantees the application of pure uniaxial tensile strain with no shear component of the stress while e.g. simultaneously measuring the resistance change of the NW. To demonstrate the potential of this approach we investigated the piezoresistivity of about 3 μm long and 100 nm thick SiNWs but in the same way one can think about the application of such a device on other geometries, other materials beyond Si as well as the use of other characterization techniques beyond electrical measurements. Therefore single-crystal SiNWs were monolithically integrated in a comb drive actuated MEMS device based on a silicon-on-insulator (SOI) wafer using the vapor-liquid-solid (VLS) growth technique. Strain values were verified by a precise measurement of the NW elongation with scanning electron microscopy (SEM). Further we employed confocal μ-Raman microscopy for in situ, high spatial resolution measurements of the strain in individual SiNWs during electrical characterization. A giant piezoresistive effect was observed, resulting in a fivefold increase in conductivity for 3% uniaxially strained SiNWs. As the EATEST approach can be easily integrated into an existing Si technology platform this architecture may pave the way toward a new generation of nonconventional devices by leveraging the strain degree of freedom.

  7. Disordered array of Au covered Silicon nanowires for SERS biosensing combined with electrochemical detection.

    Science.gov (United States)

    Convertino, Annalisa; Mussi, Valentina; Maiolo, Luca

    2016-01-01

    We report on highly disordered array of Au coated silicon nanowires (Au/SiNWs) as surface enhanced Raman scattering (SERS) probe combined with electrochemical detection for biosensing applications. SiNWs, few microns long, were grown by plasma enhanced chemical vapor deposition on common microscope slides and covered by Au evaporated film, 150 nm thick. The capability of the resulting composite structure to act as SERS biosensor was studied via the biotin-avidin interaction: the Raman signal obtained from this structure allowed to follow each surface modification step as well as to detect efficiently avidin molecules over a broad range of concentrations from micromolar down to the nanomolar values. The metallic coverage wrapping SiNWs was exploited also to obtain a dual detection of the same bioanalyte by electrochemical impedance spectroscopy (EIS). Indeed, the SERS signal and impedance modifications induced by the biomolecule perturbations on the metalized surface of the NWs were monitored on the very same three-electrode device with the Au/SiNWs acting as both working electrode and SERS probe. PMID:27112197

  8. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively.

    Science.gov (United States)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50-15000 μmoL L(-1) (cubic SiC NWs) and 5-8000 μmoL L(-1) (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L(-1) respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

  9. Complementary metal oxide semiconductor-compatible silicon nanowire biofield-effect transistors as affinity biosensors.

    Science.gov (United States)

    Duan, Xuexin; Rajan, Nitin K; Izadi, Mohammad Hadi; Reed, Mark A

    2013-11-01

    Affinity biosensors use biorecognition elements and transducers to convert a biochemical event into a recordable signal. They provides the molecule binding information, which includes the dynamics of biomolecular association and dissociation, and the equilibrium association constant. Complementary metal oxide semiconductor-compatible silicon (Si) nanowires configured as a field-effect transistor (NW FET) have shown significant advantages for real-time, label-free and highly sensitive detection of a wide range of biomolecules. Most research has focused on reducing the detection limit of Si-NW FETs but has provided less information about the real binding parameters of the biomolecular interactions. Recently, Si-NW FETs have been demonstrated as affinity biosensors to quantify biomolecular binding affinities and kinetics. They open new applications for NW FETs in the nanomedicine field and will bring such sensor technology a step closer to commercial point-of-care applications. This article summarizes the recent advances in bioaffinity measurement using Si-NW FETs, with an emphasis on the different approaches used to address the issues of sensor calibration, regeneration, binding kinetic measurements, limit of detection, sensor surface modification, biomolecule charge screening, reference electrode integration and nonspecific molecular binding. PMID:24156488

  10. Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect

    KAUST Repository

    Zhang, Qianfan

    2011-05-19

    Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographic directions. Due to distinct atomic configuration and electronic structure of SiNWs with different axial orientations, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, including binding energy, diffusion barriers, and dependence on uniaxial strain in [110], [100], [111], and [112] SiNWs. Our systematic ab initio study suggests that the Si-Li interaction is weaker when the Si-Li bond direction is aligned close to the SiNW long axis. This results in the [110] and [111] SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusion barrier along the SiNW axis lower than other pathways. Under external strain, it was found that [110] and [001] SiNWs are the most and least sensitive, respectively. For diffusion along the axial direction, the barrier increases (decreases) under tension (compression). This feature results in a considerable difference in the magnitude of the energy barrier along different diffusion pathways. © 2011 American Chemical Society.

  11. Ultra-Low Breakdown Voltage of Field Ionization in Atmospheric Air Based on Silicon Nanowires

    International Nuclear Information System (INIS)

    Classic field ionization requires extremely high positive electric fields, of the order of a few million volts per centimeter. Here we show that field ionization can occur at dramatically lower fields on the electrode of silicon nanowires (SiNWs) with dense surface states and large field enhancement factor. A field ionization structure using SiNWs as the anode has been investigated, in which the SiNWs were fabricated by improved chemical etching process. At room temperature and atmospheric pressure, breakdown of the air is reproducible with a fixed anode-to-cathode distance of 0.5 μm. The breakdown voltage is ∼38 V, low enough to be achieved by a battery-powered unit. Two reasons can be given for the low breakdown voltage. First, the gas discharge departs from the Paschen's law and the breakdown voltage decreases sharply as the gap distance falls in μm range. The other reason is the large electric field enhancement factor (β) and the high density of surface defects, which cause a highly non-uniform electric field for field emission to occur

  12. Thermally responsive silicon nanowire arrays for native/denatured-protein separation

    Science.gov (United States)

    Wang, Hongwei; Wang, Yanwei; Yuan, Lin; Wang, Lei; Yang, Weikang; Wu, Zhaoqiang; Li, Dan; Chen, Hong

    2013-03-01

    We present our findings of the selective adsorption of native and denatured proteins onto thermally responsive, native-protein resistant poly(N-isopropylacrylamide) (PNIPAAm) decorated silicon nanowire arrays (SiNWAs). The PNIPAAm-SiNWAs surface, which shows very low levels of native-protein adsorption, favors the adsorption of denatured proteins. The amount of denatured-protein adsorption is higher at temperatures above the lower critical solution temperature (LCST) of PNIPAAm. Temperature cycling surrounding the LCST, which ensures against thermal denaturation of native proteins, further increases the amount of denatured-protein adsorption. Moreover, the PNIPAAm-SiNWAs surface is able to selectively adsorb denatured protein even from mixtures of different protein species; meanwhile, the amount of native proteins in solution is kept nearly at its original level. It is believed that these results will not only enrich current understanding of protein interactions with PNIPAAm-modified SiNWAs surfaces, but may also stimulate applications of PNIPAAm-SiNWAs surfaces for native/denatured protein separation.

  13. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    Science.gov (United States)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-04-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L‑1 (cubic SiC NWs) and 5–8000 μmoL L‑1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L‑1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility.

  14. Electrostatic actuated strain engineering in monolithically integrated VLS grown silicon nanowires

    International Nuclear Information System (INIS)

    In this paper we demonstrate the fabrication and application of an electrostatic actuated tensile straining test (EATEST) device enabling strain engineering in individual suspended nanowires (NWs). Contrary to previously reported approaches, this special setup guarantees the application of pure uniaxial tensile strain with no shear component of the stress while e.g. simultaneously measuring the resistance change of the NW. To demonstrate the potential of this approach we investigated the piezoresistivity of about 3 μm long and 100 nm thick SiNWs but in the same way one can think about the application of such a device on other geometries, other materials beyond Si as well as the use of other characterization techniques beyond electrical measurements. Therefore single-crystal SiNWs were monolithically integrated in a comb drive actuated MEMS device based on a silicon-on-insulator (SOI) wafer using the vapor–liquid–solid (VLS) growth technique. Strain values were verified by a precise measurement of the NW elongation with scanning electron microscopy (SEM). Further we employed confocal μ-Raman microscopy for in situ, high spatial resolution measurements of the strain in individual SiNWs during electrical characterization. A giant piezoresistive effect was observed, resulting in a fivefold increase in conductivity for 3% uniaxially strained SiNWs. As the EATEST approach can be easily integrated into an existing Si technology platform this architecture may pave the way toward a new generation of nonconventional devices by leveraging the strain degree of freedom. (paper)

  15. Flexible Near-Infrared Photovoltaic Devices Based on Plasmonic Hot-Electron Injection into Silicon Nanowire Arrays.

    Science.gov (United States)

    Liu, Dong; Yang, Dong; Gao, Yang; Ma, Jun; Long, Ran; Wang, Chengming; Xiong, Yujie

    2016-03-24

    The development of flexible near-infrared (NIR) photovoltaic (PV) devices containing silicon meets the strong demands for solar utilization, portability, and sustainable manufacture; however, improvements in the NIR light absorption and conversion efficiencies in ultrathin crystalline Si are required. We have developed an approach to improve the quantum efficiency of flexible PV devices in the NIR spectral region by integrating Si nanowire arrays with plasmonic Ag nanoplates. The Ag nanoplates can directly harvest and convert NIR light into plasmonic hot electrons for injection into Si, while the Si nanowire arrays offer light trapping. Taking the wavelength of 800 nm as an example, the external quantum efficiency has been improved by 59 % by the integration Ag nanoplates. This work provides an alternative strategy for the design and fabrication of flexible NIR PVs. PMID:26929103

  16. Enhanced Photoelectrical Response of Hydrogenated Amorphous Silicon Single-Nanowire Solar Cells by Front-Opening Crescent Design.

    Science.gov (United States)

    Yang, Zhenhai; Cao, Guoyang; Shang, Aixue; Lei, Dang Yuan; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-12-01

    We report an approach for substantially enhancing the light-trapping and photoconversion efficiency of hydrogenated amorphous silicon (a-Si:H) single-nanowire solar cells (SNSCs) by engineering the cross section of the nanowire from circular into a front-opening crescent shape. The proposed SNSCs show a broadband and highly tunable optical absorption compared to the conventional circular counterparts under both transverse electric and transverse magnetic incidences, enabling an enhancement ratio of over 40 % in both the photocurrent density and the photoconversion efficiency in a-Si:H SNSCs with a diameter of 200 nm. We further show that the superior performance can be well maintained under a wide range of incident angle and is robust to the blunt crescent edges. PMID:27129685

  17. Enhanced Photoelectrical Response of Hydrogenated Amorphous Silicon Single-Nanowire Solar Cells by Front-Opening Crescent Design

    Science.gov (United States)

    Yang, Zhenhai; Cao, Guoyang; Shang, Aixue; Lei, Dang Yuan; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-04-01

    We report an approach for substantially enhancing the light-trapping and photoconversion efficiency of hydrogenated amorphous silicon (a-Si:H) single-nanowire solar cells (SNSCs) by engineering the cross section of the nanowire from circular into a front-opening crescent shape. The proposed SNSCs show a broadband and highly tunable optical absorption compared to the conventional circular counterparts under both transverse electric and transverse magnetic incidences, enabling an enhancement ratio of over 40 % in both the photocurrent density and the photoconversion efficiency in a-Si:H SNSCs with a diameter of 200 nm. We further show that the superior performance can be well maintained under a wide range of incident angle and is robust to the blunt crescent edges.

  18. Broadband high efficiency silicon nanowire arrays with radial diversity within diamond-like geometrical distribution for photovoltaic applications.

    Science.gov (United States)

    Al-Zoubi, Omar H; Said, Tarek M; Alher, Murtadha Abdulmueen; El-Ghazaly, Samir; Naseem, Hameed

    2015-07-27

    In this study we report novel silicon nanowire (SiNW) array structures that have near-unity absorption spectrum. The design of the new SiNW arrays is based on radial diversity of nanowires with periodic diamond-like array (DLA) structures. Different array structures are studied with a focus on two array structures: limited and broad diversity DLA structures. Numerical electromagnetic modeling is used to study the light-array interaction and to compute the optical properties of SiNW arrays. The proposed arrays show superior performance over other types of SiNW arrays. Significant enhancement of the array absorption is achieved over the entire solar spectrum of interest with significant reduction of the amount of material. The arrays show performance independent of angle of incidence up to 70 degrees, and polarization. The proposed arrays achieved ultimate efficiency as high as 39% with filling fraction as low as 19%. PMID:26367679

  19. Non-Degenerate Four-Wave Mixing in a Silicon Nanowire and its Application for One-to-Six WDM Multicasting

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua;

    2011-01-01

    We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements.......We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements....

  20. Effect of Electrical Contact Resistance in a Silicon Nanowire Thermoelectric Cooler and a Design Guideline for On-Chip Cooling Applications

    Science.gov (United States)

    Li, Y.; Buddharaju, K.; Singh, N.; Lee, S. J.

    2013-07-01

    Contact resistance gains prominence as feature size reduces to the nanometer length scale. This work studies the effects of electrical contact resistance on the performance of silicon nanowire-based thermoelectric coolers using COMSOL Multiphysics. The values of the contact resistance used to simulate the impact are experimentally extracted from a pair of thermoelectric legs with each leg made of top-down-fabricated 100 silicon nanowires having diameter of 100 nm. Analytical models agreeing well with the simulation results are provided. Lastly, a design methodology is proposed for optimum performance in on-chip cooling applications.

  1. Relaxing the electrostatic screening effect by patterning vertically-aligned silicon nanowire arrays into bundles for field emission application

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Yung-Jr, E-mail: yungjrhung@gmail.com [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Department of Photonics, National Sun Yat-sen University, No. 70, Lienhai Rd., Kaohsiung 80424, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Lee, San-Liang [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Beng, Looi Choon [Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Chang, Hsuan-Chen [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Huang, Yung-Jui [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Lee, Kuei-Yi; Huang, Ying-Sheng [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China)

    2014-04-01

    Top-down fabrication strategies are proposed and demonstrated to realize arrays of vertically-aligned silicon nanowire bundles and bundle arrays of carbon nanotube–silicon nanowire (CNT–SiNW) heterojunctions, aiming for releasing the electrostatic screening effect and improving the field emission characteristics. The trade-off between the reduction in the electrostatic screening effect and the decrease of emission sites leads to an optimal SiNW bundle arrangement which enables the lowest turn-on electric field of 1.4 V/μm and highest emission current density of 191 μA/cm{sup 2} among all testing SiNW samples. Benefiting from the superior thermal and electrical properties of CNTs and the flexible patterning technologies available for SiNWs, bundle arrays of CNT–SiNW heterojunctions show improved and highly-uniform field emission with a lower turn-on electric field of 0.9 V/μm and higher emission current density of 5.86 mA/cm{sup 2}. The application of these materials and their corresponding fabrication approaches is not limited to the field emission but can be used for a variety of emerging fields like nanoelectronics, lithium-ion batteries, and solar cells. - Highlights: • Aligned silicon nanowire (SiNW) bundle arrays are realized with top-down methods. • Growing carbon nanotubes atop SiNW bundle arrays enable uniform field emission. • A turn-on field of 0.9 V/μm and an emission current of > 5 mA/cm{sup 2} are achieved.

  2. Relaxing the electrostatic screening effect by patterning vertically-aligned silicon nanowire arrays into bundles for field emission application

    International Nuclear Information System (INIS)

    Top-down fabrication strategies are proposed and demonstrated to realize arrays of vertically-aligned silicon nanowire bundles and bundle arrays of carbon nanotube–silicon nanowire (CNT–SiNW) heterojunctions, aiming for releasing the electrostatic screening effect and improving the field emission characteristics. The trade-off between the reduction in the electrostatic screening effect and the decrease of emission sites leads to an optimal SiNW bundle arrangement which enables the lowest turn-on electric field of 1.4 V/μm and highest emission current density of 191 μA/cm2 among all testing SiNW samples. Benefiting from the superior thermal and electrical properties of CNTs and the flexible patterning technologies available for SiNWs, bundle arrays of CNT–SiNW heterojunctions show improved and highly-uniform field emission with a lower turn-on electric field of 0.9 V/μm and higher emission current density of 5.86 mA/cm2. The application of these materials and their corresponding fabrication approaches is not limited to the field emission but can be used for a variety of emerging fields like nanoelectronics, lithium-ion batteries, and solar cells. - Highlights: • Aligned silicon nanowire (SiNW) bundle arrays are realized with top-down methods. • Growing carbon nanotubes atop SiNW bundle arrays enable uniform field emission. • A turn-on field of 0.9 V/μm and an emission current of > 5 mA/cm2 are achieved

  3. Translating silicon nanowire BioFET sensor-technology to embedded point-of-care medical diagnostics

    DEFF Research Database (Denmark)

    Pfreundt, Andrea; Zulfiqar, Azeem; Patou, François;

    2013-01-01

    Silicon nanowire and nanoribbon biosensors have shown great promise in the detection of biomarkers at very low concentrations. Their high sensitivity makes them ideal candidates for use in early-stage medical diagnostics and further disease monitoring where low amounts of biomarkers need to be...... be immobilized in a parallel manner without the use of a spotting system using various chemistries depending on the chosen headgroup in the monolayer. The system is designed to work with a single tube at the outlet and is able to mix and deliver immobilization reactants and antibody solution as well...

  4. Wavelength conversion of 28 GBaud 16-QAM signals based on four-wave mixing in a silicon nanowire.

    Science.gov (United States)

    Adams, Rhys; Spasojevic, Mina; Chagnon, Mathieu; Malekiha, Mahdi; Li, Jia; Plant, David V; Chen, Lawrence R

    2014-02-24

    We demonstrate error-free wavelength conversion of 28 GBaud 16-QAM single polarization (112 Gb/s) signals based on four-wave mixing in a dispersion engineered silicon nanowire (SNW). Wavelength conversion covering the entire C-band is achieved using a single pump. We characterize the performance of the wavelength converter subsystem through the electrical signal to noise ratio penalty as well as the bit error rate of the converted signal as a function of input signal power. Moreover, we evaluate the degradation of the optical signal to noise ratio due to wavelength conversion in the SNW. PMID:24663730

  5. Glucose-Derived Porous Carbon-Coated Silicon Nanowires as Efficient Electrodes for Aqueous Micro-Supercapacitors.

    Science.gov (United States)

    Devarapalli, Rami Reddy; Szunerits, Sabine; Coffinier, Yannick; Shelke, Manjusha V; Boukherroub, Rabah

    2016-02-24

    In this study, we report on carbon coating of vertically aligned silicon nanowire (SiNWs) arrays via a simple hydrothermal process using glucose as carbon precursor. Using this process, a thin carbon layer is uniformly deposited on the SiNWs. Under optimized conditions, the coated SiNWs electrode showed better electrochemical energy storage capacity as well as exceptional stability in aqueous system as compared to uncoated SiNWs. The as-measured capacitance reached 25.64 mF/cm(2) with a good stability up to 25000 charging/discharging cycles in 1 M Na2SO4 aqueous solution. PMID:26866275

  6. Effect of acid vapor etching on morphological and opto-electric properties of flat silicon and silicon nanowire arrays: A comparative study

    Science.gov (United States)

    Amri, Chohdi; Ouertani, Rachid; Hamdi, Abderrahmen; Ezzaouia, Hatem

    2016-03-01

    In this paper, we report a comparative study between porous silicon (pSi) and porous silicon nanowires (pSiNWs). Acid Vapor Etching (AVE) treatment has been used to perform porous structure on flat Si and SiNWs array substrates respectively. SiNW structure is prepared by the widely used Silver catalyzed etching method. SEM and TEM images show that AVE treatment induces porous structure in the whole Si wafer and the SiNW sidewall. Comparatively to pSi, pSiNWs exhibit a low reflectivity in the whole spectral range which decreases with etching duration. However, the reflectivity of pSi changes with porous layer thickness. Both pSi and pSiNWs exhibit a significant PL peak situated at 2 eV. PL peaks are attributed to the quantum confinement effect in the silicon nanocrystallites (SiNCs). We discussed the significant enhancement in the peak intensities and a shift toward lower energy displayed in Raman spectra for both pSi and pSiNWs. We reported a correlative study of the AVE treatment effect on the minority carrier life time of flat silicon and SiNW arrays with the passivation effect of chemical induced silicon oxides highlighted by FTIR spectra.

  7. Broadband High Efficiency Fractal-Like and Diverse Geometry Silicon Nanowire Arrays for Photovoltaic Applications

    Science.gov (United States)

    AL-Zoubi, Omar H.

    Solar energy has many advantages over conventional sources of energy. It is abundant, clean and sustainable. One way to convert solar energy directly into electrical energy is by using the photovoltaic solar cells (PVSC). Despite PVSC are becoming economically competitive, they still have high cost and low light to electricity conversion efficiency. Therefore, increasing the efficiency and reducing the cost are key elements for producing economically more competitive PVSC that would have significant impact on energy market and saving environment. A significant percentage of the PVSC cost is due to the materials cost. For that, thin films PVSC have been proposed which offer the benefits of the low amount of material and fabrication costs. Regrettably, thin film PVSC show poor light to electricity conversion efficiency because of many factors especially the high optical losses. To enhance conversion efficiency, numerous techniques have been proposed to reduce the optical losses and to enhance the absorption of light in thin film PVSC. One promising technique is the nanowire (NW) arrays in general and the silicon nanowire (SiNW) arrays in particular. The purpose of this research is to introduce vertically aligned SiNW arrays with enhanced and broadband absorption covering the entire solar spectrum while simultaneously reducing the amount of material used. To this end, we apply new concept for designing SiNW arrays based on employing diversity of physical dimensions, especially radial diversity within certain lattice configurations. In order to study the interaction of light with SiNW arrays and compute their optical properties, electromagnetic numerical modeling is used. A commercial numerical electromagnetic solver software package, high frequency structure simulation (HFSS), is utilized to model the SiNW arrays and to study their optical properties. We studied different geometries factors that affect the optical properties of SiNW arrays. Based on this study, we

  8. Facet-Selective Epitaxy of Compound Semiconductors on Faceted Silicon Nanowires.

    Science.gov (United States)

    Mankin, Max N; Day, Robert W; Gao, Ruixuan; No, You-Shin; Kim, Sun-Kyung; McClelland, Arthur A; Bell, David C; Park, Hong-Gyu; Lieber, Charles M

    2015-07-01

    Integration of compound semiconductors with silicon (Si) has been a long-standing goal for the semiconductor industry, as direct band gap compound semiconductors offer, for example, attractive photonic properties not possible with Si devices. However, mismatches in lattice constant, thermal expansion coefficient, and polarity between Si and compound semiconductors render growth of epitaxial heterostructures challenging. Nanowires (NWs) are a promising platform for the integration of Si and compound semiconductors since their limited surface area can alleviate such material mismatch issues. Here, we demonstrate facet-selective growth of cadmium sulfide (CdS) on Si NWs. Aberration-corrected transmission electron microscopy analysis shows that crystalline CdS is grown epitaxially on the {111} and {110} surface facets of the Si NWs but that the Si{113} facets remain bare. Further analysis of CdS on Si NWs grown at higher deposition rates to yield a conformal shell reveals a thin oxide layer on the Si{113} facet. This observation and control experiments suggest that facet-selective growth is enabled by the formation of an oxide, which prevents subsequent shell growth on the Si{113} NW facets. Further studies of facet-selective epitaxial growth of CdS shells on micro-to-mesoscale wires, which allows tuning of the lateral width of the compound semiconductor layer without lithographic patterning, and InP shell growth on Si NWs demonstrate the generality of our growth technique. In addition, photoluminescence imaging and spectroscopy show that the epitaxial shells display strong and clean band edge emission, confirming their high photonic quality, and thus suggesting that facet-selective epitaxy on NW substrates represents a promising route to integration of compound semiconductors on Si. PMID:26057208

  9. A Stable Flexible Silicon Nanowire Array as Anode for High-Performance Lithium-ion Batteries

    International Nuclear Information System (INIS)

    Highlights: • A flexible SiNW array in PDMS structure is designed and fabricated as Li-ion battery anode material. • The aggregation and fracture of SiNWs are alleviated by the flexible PDMS skeleton during the process of charge and discharge. • The loose SiO2 shells coating on the SiNWscould form the protective layer in charge/discharge. • The as-obtain flexible SiNW array/PDMS composite exhibits a much better cycling stability. - Abstract: A Silicon nanowire (SiNW) array inserted into flexible poly-dimethylsiloxane (SiNW array/PDMS) composite structure as anode with high capacity and long-term cycling stability is synthesized by a cost-effective and scalable method. In this structure, the aggregation and fracture of SiNWs are alleviated by the flexible PDMS skeleton. Act as the main active component, the SiNWs are coated by loose SiO2 shells. These loose SiO2 shells not only provide space for the large volume changes of SiNW, but also react with the electrolyte and form the stable protective layer during the processes of the lithiation and delithiation. These two functions could improve the cycling stability and columbic efficiency of the SiNWs. The as-obtain flexible SiNW array/PDMS composite structure exhibits excellent long-term cycling stability with a specific capacity of 887.2 mA·h·g−1 and capacity retention of ∼83.4% over 350 cycles at 0.5 C rate compared with the fifteenth cycle. The design of this new structure provides a potential way for developing other functional composite materials

  10. Silicon nanowires as field-effect transducers for biosensor development: A review

    Energy Technology Data Exchange (ETDEWEB)

    Noor, M. Omair; Krull, Ulrich J., E-mail: ulrich.krull@utoronto.ca

    2014-05-01

    Highlights: • Nanoscale field-effect transducers interrogate surface charge by conductivity changes. • The nanometer dimensions of SiNWs facilitate sensitive detection of biomolecules. • SiNWs can be fabricated by bottom–up or top–down approaches. • Device parameters and solution-phase conditions strongly influence analytical performance. - Abstract: The unique electronic properties and miniaturized dimensions of silicon nanowires (SiNWs) are attractive for label-free, real-time and sensitive detection of biomolecules. Sensors based on SiNWs operate as field effect transistors (FETs) and can be fabricated either by top–down or bottom–up approaches. Advances in fabrication methods have allowed for the control of physicochemical and electronic properties of SiNWs, providing opportunity for interfacing of SiNW-FET probes with intracellular environments. The Debye screening length is an important consideration that determines the performance and detection limits of SiNW-FET sensors, especially at physiologically relevant conditions of ionic strength (>100 mM). In this review, we discuss the construction and application of SiNW-FET sensors for detection of ions, nucleic acids and protein markers. Advantages and disadvantages of the top–down and bottom–up approaches for synthesis of SiNWs are discussed. An overview of various methods for surface functionalization of SiNWs for immobilization of selective chemistry is provided in the context of impact on the analytical performance of SiNW-FET sensors. In addition to in vitro examples, an overview of the progress of use of SiNW-FET sensors for ex vivo studies is also presented. This review concludes with a discussion of the future prospects of SiNW-FET sensors.

  11. Influence of the polymer matrix on the efficiency of hybrid solar cells based on silicon nanowires

    International Nuclear Information System (INIS)

    Highlights: ► Hybrid solar cells based on silicon nanowires have been fabricated. ► The relation between the morphology of the composite thin films and the charge transfer between the polymer matrices and SiNWs has been examined. ► We have investigated the effect of the polymer matrix on the photovoltaic characteristics. - Abstract: Poly (N-vinylcarbazole) (PVK):SiNWs and poly (2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenyl vinylene) (MEH-PPV):SiNWs bulk-heterojunctions (BHJ) have been elaborated from blends of SiNWs and the polymer in solution from a common solvent. Optical properties of these nanocomposites have been investigated by UV–vis absorption and photoluminescence (PL) spectral measurements. We have studied the charge transfer between SiNWs and the two polymers using the photoluminescence quenching of PVK and MEH-PPV which is a convenient signature of the reduced radiative recombination of the generated charge pairs upon exciton dissociation. We found that PVK and SiNWs constitutes the better donor–acceptor system. In order to understand the difference between PVK:SiNWs or MEH-PPV:SiNWs behaviours, photoluminescence responses were correlated with the topography (SEM) of the thin films. The photovoltaic effect of ITO/PEDOT:PSS/SiNWs:PVK/Al and ITO/PEDOT:PSS/SiNWs:MEH-PPV/Al structures was studied by current–voltage (I–V) measurements in dark and under illumination and interpreted on the basis of the charge transfer differences resulting from the morphologies.

  12. Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures

    Science.gov (United States)

    Mwangi, Joseph N.; Wang, Ning; Ritts, Andrew; Kunz, James L.; Ingersoll, Christopher G.; Li, Hao; Deng, Baolin

    2011-01-01

    Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 h. Midges, mussels, and oligochaetes were exposed only to sonicated SiCNW in water for 96 h. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 d (44% SiCNW on dry wt basis). Mean 48-h survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-h exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-d exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods, sonicated SiCNW in water were acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.

  13. Silicon nanowires as field-effect transducers for biosensor development: A review

    International Nuclear Information System (INIS)

    Highlights: • Nanoscale field-effect transducers interrogate surface charge by conductivity changes. • The nanometer dimensions of SiNWs facilitate sensitive detection of biomolecules. • SiNWs can be fabricated by bottom–up or top–down approaches. • Device parameters and solution-phase conditions strongly influence analytical performance. - Abstract: The unique electronic properties and miniaturized dimensions of silicon nanowires (SiNWs) are attractive for label-free, real-time and sensitive detection of biomolecules. Sensors based on SiNWs operate as field effect transistors (FETs) and can be fabricated either by top–down or bottom–up approaches. Advances in fabrication methods have allowed for the control of physicochemical and electronic properties of SiNWs, providing opportunity for interfacing of SiNW-FET probes with intracellular environments. The Debye screening length is an important consideration that determines the performance and detection limits of SiNW-FET sensors, especially at physiologically relevant conditions of ionic strength (>100 mM). In this review, we discuss the construction and application of SiNW-FET sensors for detection of ions, nucleic acids and protein markers. Advantages and disadvantages of the top–down and bottom–up approaches for synthesis of SiNWs are discussed. An overview of various methods for surface functionalization of SiNWs for immobilization of selective chemistry is provided in the context of impact on the analytical performance of SiNW-FET sensors. In addition to in vitro examples, an overview of the progress of use of SiNW-FET sensors for ex vivo studies is also presented. This review concludes with a discussion of the future prospects of SiNW-FET sensors

  14. Improved silicon nanowire field-effect transistors for fast protein-protein interaction screening.

    Science.gov (United States)

    Lin, Ti-Yu; Li, Bor-Ran; Tsai, Sheng-Ta; Chen, Chien-Wei; Chen, Chung-Hsuan; Chen, Yit-Tsong; Pan, Chien-Yuan

    2013-02-21

    Understanding how proteins interact with each other is the basis for studying the biological mechanisms behind various physiological activities. Silicon nanowire field-effect transistors (SiNW-FETs) are sensitive sensors used to detect biomolecular interactions in real-time. However, the majority of the applications that use SiNW-FETs are for known interactions between different molecules. To explore the capability of SiNW-FETs as fast screening devices to identify unknown interacting molecules, we applied mass spectrometry (MS) to analyze molecules reversibly bound to the SiNW-FETs. Calmodulin (CaM) is a Ca(2+)-sensing protein that is ubiquitously expressed in cells and its interaction with target molecules is Ca(2+)-dependent. By modifying the SiNW-FET surface with glutathione, glutathione S-transferase (GST)-tagged CaM binds reversibly to the SiNW-FET. We first verified the Ca(2+)-dependent interaction between GST-CaM and purified troponin I, which is involved in muscle contraction, through the conductance changes of the SiNW-FET. Furthermore, the cell lysate containing overexpressed Ca(2+)/CaM-dependent protein kinase IIα induced a conductance change in the GST-CaM-modified SiNW-FET. The bound proteins were eluted and subsequently identified by MS as CaM and kinase. In another example, candidate proteins from neuronal cell lysates interacting with calneuron I (CalnI), a CaM-like protein, were captured with a GST-CalnI-modified SiNW-FET. The proteins that interacted with CalnI were eluted and verified by MS. The Ca(2+)-dependent interaction between GST-CalnI and one of the candidates, heat shock protein 70, was re-confirmed via the SiNW-FET measurement. Our results demonstrate the effectiveness of combining MS with SiNW-FETs to quickly screen interacting molecules from cell lysates. PMID:23235921

  15. Surface potential variations on a silicon nanowire transistor in biomolecular modification and detection

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Chia-Chang; Chiang, Pei-Ling; Lin, Tsung-Wu; Chen, Yit-Tsong [Institute of Atomic and Molecular Sciences, Academia Sinica, PO Box 23-166, Taipei 106, Taiwan (China); Sun, Chih-Jung; Tsai, Ming-Hsueh [Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 106, Taiwan (China); Chang, Yun-Chorng, E-mail: ychang6@mail.ncku.edu.tw, E-mail: ytcchem@ntu.edu.tw [Institute of Electro-Optical Science and Engineering, National Cheng Kung University, No. 1, Ta-Hsueh Road, Tainan 701, Taiwan (China)

    2011-04-01

    Using a silicon nanowire field-effect transistor (SiNW-FET) for biomolecule detections, we selected 3-(mercaptopropyl)trimethoxysilane (MPTMS), N-[6-(biotinamido)hexyl]-3{sup '}-(2{sup '}-pyridyldithio) propionamide (biotin-HPDP), and avidin, respectively, as the designated linker, receptor, and target molecules as a study model, where the biotin molecules were modified on the SiNW-FET to act as a receptor for avidin. We applied high-resolution scanning Kelvin probe force microscopy (KPFM) to detect the modified/bound biomolecules by measuring the induced change of the surface potential ({Delta}{Phi}{sup s}) on the SiNW-FET under ambient conditions. After biotin-immobilization and avidin-binding, the {Delta}{Phi}{sup s} on the SiNW-FET characterized by KPFM was demonstrated to correlate to the conductance change inside the SiNW-FET acquired in aqueous solution. The {Delta}{Phi}{sup s} values on the SiNW-FET caused by the same biotin-immobilization and avidin-binding were also measured from drain current versus gate voltage curves (I{sub d}-V{sub g}) in both aqueous condition and dried state. For comparison, we also study the {Delta}{Phi}{sup s} values on a Si wafer caused by the same biotin-immobilization and avidin-binding through KPFM and {zeta} potential measurements. This study has demonstrated that the surface potential measurement on a SiNW-FET by KPFM can be applied as a diagnostic tool that complements the electrical detection with a SiNW-FET sensor. Although the KPFM experiments were carried out under ambient conditions, the measured surface properties of a SiNW-FET are qualitatively valid compared with those obtained by other biosensory techniques performed in liquid environment.

  16. New Nanobiocomposite Materials for Bioelectronic Devices

    Science.gov (United States)

    Pankratov, D. V.; González-Arribas, E.; Parunova, Yu. M.; Gorbacheva, M. A.; Zeyfman, Yu. S.; Kuznetsov, S. V.; Lipkin, A. V.; Shleev, S. V.

    2015-01-01

    We have developed and synthesized nanobiocomposite materials based on graphene, poly(3,4-ethylenedioxythiophene), and glucose oxidase immobilized on the surface of various nanomaterials (gold nanoparticles and multi-walled carbon nanotubes) of different sizes (carbon nanotubes of different diameters). Comparative studies of the possible influence of the nanomaterial’s nature on the bioelectrocatalytic characteristics of glucose- oxidizing bioanodes in a neutral phosphate buffer solution demonstrated that the bioelectrocatalytic current densities of nanocomposite-based bioanodes are only weakly dependent on the size of the nanomaterial and are primarily defined by its nature. The developed nanobiocomposites are promising materials for new bioelectronic devices due to the ease in adjusting their capacitive and bioelectrocatalytic characteristics, which allows one to use them for the production of dual-function electrodes: i.e., electrodes which are capable of generating and storing electric power simultaneously. PMID:25927006

  17. Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wanghua; Roca i Cabarrocas, Pere [Laboratoire de Physique des Interfaces et Couches Minces (LPICM), UMR 7647, CNRS, Ecole Polytechnique, 91128 Palaiseau (France); Pareige, Philippe; Castro, Celia [Groupe de Physique des Matériaux (GPM), Université et INSA de Rouen, UMR 6634, CNRS, Av. de l' Université, BP 12, 76801 Saint Etienne du Rouvray (France); Xu, Tao; Grandidier, Bruno; Stiévenard, Didier [Institut d' Electronique et de Microélectronique et de Nanotechnologies (IEMN), UMR 8520, CNRS, Département ISEN, 41 bd Vauban, 59046 Lille Cedex (France)

    2015-09-14

    By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process.

  18. Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

    International Nuclear Information System (INIS)

    By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process

  19. Control of the micrometric scale morphology of silicon nanowires through ion irradiation-induced metal dewetting

    Science.gov (United States)

    Lo Savio, R.; Repetto, L.; Guida, P.; Angeli, E.; Firpo, G.; Volpe, A.; Ierardi, V.; Valbusa, U.

    2016-08-01

    We propose ion-induced dewetting of Au thin films as a mechanism to modify and control the morphology of Si nanowires formed through metal-assisted chemical etching. We show that the patterns formed upon irradiation resemble those typical of dewetting phenomena, with a characteristic length in the nanometer range. Irradiated Au films are then used as a template for the fabrication of Si nanowires, and we show that a long-range order exists also in etched substrates, although at much longer length scales in the micrometer range. Investigation of the optical properties reveals that the Si nanowires emit broadband photoluminescence peaked at 700 nm. The proposed synthesis method allows tuning the morphological features of the nanowire bundles at the nanoscale without affecting the optical properties. This approach can be exploited for the engineering of nanowires-based devices where the morphological features become important.

  20. Nanoscale neuroelectrode modification via sub-20 nm silicon nanowires through self-assembly of block copolymers.

    Science.gov (United States)

    Mokarian-Tabari, Parvaneh; Vallejo-Giraldo, Catalina; Fernandez-Yague, Marc; Cummins, Cian; Morris, Michael A; Biggs, Manus J P

    2015-02-01

    Neuroprosthetic technologies for therapeutic neuromodulation have seen major advances in recent years but these advances have been impeded due to electrode failure or a temporal deterioration in the device recording or electrical stimulation potential. This deterioration is attributed to an intrinsic host tissue response, namely glial scarring or gliosis, which prevents the injured neurons from sprouting, drives neurite processes away from the neuroelectrode and increases signal impedance by increasing the distance between the electrode and its target neurons. To address this problem, there is a clinical need to reduce tissue encapsulation of the electrodes in situ and improve long-term neuroelectrode function. Nanotopographical modification has emerged as a potent methodology for the disruption of protein adsorption and cellular adhesion in vitro. This study investigates the use of block copolymer self-assembly technique for the generation of sub-20 nm nanowire features on silicon substrates. Critically, these nanostructures were observed to significantly reduce electrical impedance and increase conductivity. Human neuroblastoma SH-SY5Y cells cultured on nanowire substrates for up to 14 days were associated with enhanced focal adhesion reinforcement and a reduction in proliferation. We conclude that nanowire surface modulation may offer significant potential as an electrode functionalization strategy. PMID:25677116

  1. Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

    Science.gov (United States)

    Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

    2016-06-28

    Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect. PMID:27276167

  2. Monolithically Integrated InGaAs Nanowires on 3D Structured Silicon-on-Insulator as a New Platform for Full Optical Links.

    Science.gov (United States)

    Kim, Hyunseok; Farrell, Alan C; Senanayake, Pradeep; Lee, Wook-Jae; Huffaker, Diana L

    2016-03-01

    Monolithically integrated III-V semiconductors on a silicon-on-insulator (SOI) platform can be used as a building block for energy-efficient on-chip optical links. Epitaxial growth of III-V semiconductors on silicon, however, has been challenged by the large mismatches in lattice constants and thermal expansion coefficients between epitaxial layers and silicon substrates. Here, we demonstrate for the first time the monolithic integration of InGaAs nanowires on the SOI platform and its feasibility for photonics and optoelectronic applications. InGaAs nanowires are grown not only on a planar SOI layer but also on a 3D structured SOI layer by catalyst-free metal-organic chemical vapor deposition. The precise positioning of nanowires on 3D structures, including waveguides and gratings, reveals the versatility and practicality of the proposed platform. Photoluminescence measurements exhibit that the composition of ternary InGaAs nanowires grown on the SOI layer has wide tunability covering all telecommunication wavelengths from 1.2 to 1.8 μm. We also show that the emission from an optically pumped single nanowire is effectively coupled and transmitted through an SOI waveguide, explicitly showing that this work lays the foundation for a new platform toward energy-efficient optical links. PMID:26901448

  3. Growth characteristics of silicon nanowires synthesized by vapor-liquid-solid growth in nanoporous alumina templates

    Science.gov (United States)

    Lew, Kok-Keong; Redwing, Joan M.

    2003-06-01

    The fabrication of Si nanowires has been demonstrated using a combination of template-directed synthesis and vapor-liquid-solid (VLS) growth. The use of nanoporous alumina membranes for VLS growth provides control over nanowire diameter while also enabling the production of single crystal material. An investigation of the growth characteristics of Si nanowires over a temperature range from 400°C to 600°C, and over a SiH 4 partial pressure range from 0.13 to 0.65 Torr was carried out. The length of Si nanowires was found to be linearly dependent on growth time over this range of conditions. The nanowire growth rate increased from 0.068 μm/min at 400°C to 0.52 μm/min at 500°C at a constant SiH 4 partial pressure of 0.65 Torr. At temperatures greater than 500°C, Si deposited on the top surface and pore walls of the membrane thereby reducing the nanowire growth rate. The growth rate versus temperature data was used to calculate an activation energy of 22 kcal/mol for the nanowire growth process. This activation energy is believed to be associated with the decomposition of SiH 4 on the Au-Si liquid surface, which is considered to be the rate-determining step in the VLS growth process.

  4. Highly sensitive silicon nanowire biosensor with novel liquid gate control for detection of specific single-stranded DNA molecules.

    Science.gov (United States)

    Adam, Tijjani; Hashim, U

    2015-05-15

    The study demonstrates the development of a liquid-based gate-control silicon nanowire biosensor for detection of specific single-stranded DNA (ssDNA) molecules. The sensor was fabricated using conventional photolithography coupled with an inductively coupled plasma dry etching process. Prior to the application of DNA to the device, its linear response to pH was confirmed by serial dilution from pH 2 to pH 14. Then, the sensor surface was silanized and directly aminated with (3-aminopropyl) triethoxysilane to create a molecular binding chemistry for biofunctionalization. The resulting Si‒O‒Si‒ components were functionalized with receptor ssDNA, which interacted with the targeted ssDNA to create a field across the silicon nanowire and increase the current. The sensor shows selectivity for the target ssDNA in a linear range from target ssDNA concentrations of 100 pM to 25 nM. With its excellent detection capabilities, this sensor platform is promising for detection of specific biomarkers and other targeted proteins. PMID:25453738

  5. High-k materials in the electrolyte/insulator/silicon configuration. Characterization and application in bio-electronics; Hoch-k-Materialien in der Elektrolyt/Isolator/Silizium-Konfiguration. Charakterisierung und Anwendung in der Bioelektronik

    Energy Technology Data Exchange (ETDEWEB)

    Wallrapp, F.

    2006-12-19

    In order to elicit action potentials in nerve cells adhered on electrodes, a certain current is required across the electrode. Electrochemical reactions may cause damage to cells and electrodes. This is evaded by using silicon electrodes which are insulated by a dielectric. In doing so, only capacitive current is flowing, and electrochemical are avoided. The aim of this work was to fabricate novel stimulation chips exhibiting an enhanced capacitance which render new biological applications possible. These chips were to be characterized and used for the stimulation of cells. The formerly used dielectric SiO{sub 2} was replaced by HfO{sub 2} and TiO{sub 2}, with both of them featuring a higher dielectric constant. They were deposited on the silicon substrate by ALD (atomic layer deposition). The chips were characterized in the electrolyte/insulator/semiconductor (EIS) configuration. Owing to the low leakage current of the EIS configuration, the characterization of the high-k materials was possible in more detail as compared to using a metallic top contact (MIS configuration). The voltage-dependent capacitances of the HfO{sub 2} films could be interpreted by means of a common metal/SiO{sub 2}/silicon system. In contrast, the TiO{sub 2} films exhibited interesting properties which could only be rationalized with the help of numerical calculations assuming free electrons in the TiO{sub 2}. The low-lying conduction band of TiO{sub 2} caused accumulation of electrons within the TiO{sub 2} for certain voltages, which led to an enhanced capacitance. The effects of high voltages, frequency, film thickness and interlayer composition were examined and brought into compliance with the model. The novel TiO{sub 2} stimulation devices featured a five-fold capacitance increase as compared to former SiO{sub 2} chips. Using them, two fundamental stimulation mechanisms were induced in HEK293 cells expressing the recombinant potassium channel Kv1.3: Opening of ion channels and

  6. Self-aligned multi-channel silicon nanowire field-effect transistors

    Science.gov (United States)

    Zhu, Hao; Li, Qiliang; Yuan, Hui; Baumgart, Helmut; Ioannou, Dimitris E.; Richter, Curt A.

    2012-12-01

    Si nanowire field effect transistors (SiNW FETs) with multiple nanowire channels and different gate lengths have been fabricated by using a directed assembly approach combined with a standard photolithographic process. The electrical characteristics of SiNW FETs containing different numbers of nanowire channels were measured and compared. The multi-channel SiNW FETs show excellent performance: small subthreshold slope (≈75 mV/dec), large ON/OFF ratio (≈108), good break-down voltage (>30 V) and good carrier mobility (μp ≈ 100 cm2 V-1s-1). These excellent device properties were achieved by using a clean self-alignment process and an improved device structure with Schottky barriers at the source and drain contacts. Such high-performance multi-nanowire FETs are attractive for logic, memory, and sensor applications.

  7. Coaxial nanowire resonant tunneling diodes from non-polar AlN/GaN on silicon

    Science.gov (United States)

    Carnevale, S. D.; Marginean, C.; Phillips, P. J.; Kent, T. F.; Sarwar, A. T. M. G.; Mills, M. J.; Myers, R. C.

    2012-04-01

    Resonant tunneling diodes are formed using AlN/GaN core-shell nanowire heterostructures grown by plasma assisted molecular beam epitaxy on n-Si(111) substrates. By using a coaxial geometry, these devices take advantage of non-polar (m-plane) nanowire sidewalls. Device modeling predicts non-polar orientation should enhance resonant tunneling compared to a polar structure, and that AlN double barriers will lead to higher peak-to-valley current ratios compared to AlGaN barriers. Electrical measurements of ensembles of nanowires show negative differential resistance appearing only at cryogenic temperature. Individual nanowire measurements show negative differential resistance at room temperature with peak current density of 5 × 105 A/cm2.

  8. Control of defects in a novel aluminum-induced heteroepitaxial growth of AlxGal-xP nanocrystals on silicon nanowires

    International Nuclear Information System (INIS)

    Aluminum-induced heteroepitaxial growth of aluminum gallium phosphide nanocrystals (AlxGal-xP NCs) has been achieved on both silicon substrate and the tips of Al-catalyzed silicon nanowires (Si NWs). Al-induced growth is a silicon complementary metal–oxide-semiconductor compatible solution, and a growth mechanism of AlxGal-xP NCs was proposed. The decrease in structural defects in AlxGal-xP NCs grown heteroepitaxially on Si NWs was confirmed by transmission electron microscopy and Raman spectroscopy

  9. In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

    Science.gov (United States)

    Yibin, Gong; Pengfei, Dai; Anran, Gao; Tie, Li; Ping, Zhou; Yuelin, Wang

    2011-12-01

    Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm/min) and vertical (1.7 nm/min) dimensions. A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly, yielding enhanced field effect transistor (FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart, which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality of the (111) plane, as well as the bulk depletion property should be the causes of this electrical enhancement, which implies the great potential of the as-made cost-effective SiNW FET device in many fields.

  10. In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

    International Nuclear Information System (INIS)

    Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm/min) and vertical (1.7 nm/min) dimensions. A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly, yielding enhanced field effect transistor (FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart, which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality of the (111) plane, as well as the bulk depletion property should be the causes of this electrical enhancement, which implies the great potential of the as-made cost-effective SiNW FET device in many fields. (semiconductor materials)

  11. XPS analysis by exclusion of a-carbon layer on silicon carbide nanowires by a gold catalyst-supported metal-organic chemical vapor deposition method.

    Science.gov (United States)

    Nam, Sang-Hun; Kim, Myoung-Hwa; Hyun, Jae-Sung; Kim, Young Dok; Boo, Jin-Hyo

    2010-04-01

    Silicon carbide (SiC) nano-structures would be favorable for application in high temperature, high power, and high frequency nanoelectronic devices. In this study, we have deposited cubic-SiC nanowires on Au-deposited Si(001) substrates using 1,3-disilabutane as a single molecular precursor through a metal-organic chemical vapor deposition (MOCVD) method. The general deposition pressure and temperature were 3.0 x 10(-6) Torr and 1000 degrees C respectively, with the deposition carried out for 1 h. Au played an important role as a catalyst in growing the SiC nanowires. SiC nanowires were grown using a gold catalyst, with amorphous carbon surrounding the final SiC nanowire. Thus, the first step involved removal of the remaining SiO2, followed by slicing of the amorphous carbon into thin layers using a heating method. Finally, the thinly sliced amorphous carbon is perfectly removed using an Ar sputtering method. As a result, this method may provide more field emission properties for the SiC nanowires that are normally inhibited by the amorphous carbon layer. Therefore, exclusion of the amorphous carbon layer is expected to improve the overall emission properties of SiC nanowires. PMID:20355494

  12. pH driven addressing of silicon nanowires onto Si3N4/SiO2 micro-patterned surfaces

    Science.gov (United States)

    Cloarec, Jean-Pierre; Chevalier, Céline; Genest, Jonathan; Beauvais, Jacques; Chamas, Hassan; Chevolot, Yann; Baron, Thierry; Souifi, Abdelkader

    2016-07-01

    pH was used as the main driving parameter for specifically immobilizing silicon nanowires onto Si3N4 microsquares at the surface of a SiO2 substrate. Different pH values of the coating aqueous solution enabled to experimentally distribute nanowires between silicon nitride and silicon dioxide: at pH 3 nanowires were mainly anchored on Si3N4; they were evenly distributed between SiO2 and Si3N4 at pH 2.8; and they were mainly anchored on SiO2 at pH 2. A theoretical model based on DLVO theory and surface protonation/deprotonation equilibria was used to study how, in adequate pH conditions, Si nanowires could be anchored onto specific regions of a patterned Si3N4/SiO2 surface. Instead of using capillary forces, or hydrophilic/hydrophobic contrast between the two types of materials, the specificity of immobilization could rely on surface electric charge contrasts between Si3N4 and SiO2. This simple and generic method could be used for addressing a large diversity of nano-objects onto patterned substrates.

  13. Phase-coherent quantum transport in silicon nanowires based on Wigner transport equation: Comparison with the nonequilibrium-Green-function formalism

    Science.gov (United States)

    Barraud, Sylvain

    2009-09-01

    Various theoretical formulations are proposed for investigating the carrier transport in nanoscale electronic devices. In this paper, a discrete formulation of the Wigner transport equation (WTE) for the self-consistent simulation of phase-coherent quantum transport in silicon nanowire metal-oxide-semiconductor field-effect transistor (MOSFET) devices is presented. The device is simulated using an effective-mass Hamiltonian within the mode-space approximation. The numerical scheme proposed in this work solves self-consistently three dimensional Poisson's equation, two dimensional Schrödinger's equation in each cross-sectional plane of the nanowire, and the steady-state one dimensional WTE for each conduction mode to handle the quantum transport along the channel. Details on numerical implementation of the Wigner function method are given, and the results are compared with those of the nonequilibrium Green's function (NEGF) method in the ballistic limit. The calculations of current-voltage electrical characteristics of surround-gated silicon nanowires are performed using both NEGF and WTE formulations. The good agreement observed between these approaches means that a direct solution of the WTE is an accurate simulation method for modeling the ballistic quantum transport in silicon nanowire MOSFETs.

  14. Small signal modulation characteristics of red-emitting (λ = 610 nm) III-nitride nanowire array lasers on (001) silicon

    KAUST Repository

    Jahangir, Shafat

    2015-02-16

    The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and α-parameter, and large differential gain (3.1 × 10-17 cm2).

  15. Epitaxial silicon nanowire growth catalyzed by gold dot arrays from electron beam lithography patterning using silane precursors

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Bjoern; Broenstrup, Gerald; Huebner, Uwe; Christiansen, Silke [Institut fuer Photonische Technologien e.V., Abt. Halbleiter Nanostrukturen, Jena (Germany)

    2010-07-01

    Ordered arrays of silicon nanowires (SiNWs) are promising building blocks for a variety of photonic, photovoltaic and sensor applications. In our approach to create SiNWs we use electron beam lithography (EBL) and thermal metal evaporation to create nano-patterned arrays of gold nanodots on a Si(111) wafer. These Au dots are subsequently used to catalyze the bottom-up growth of SiNWs that follow the vapor-liquid-solid (VLS) growth mechanism using silane in a CVD reactor. The grown nanowires are characterized structurally using SEM, TEM and electron backscatter diffraction (EBSD). We observe epitaxial growth of the SiNWs on the Si(111) wafer and we are able to control the growth direction to be either dominated by <111> or <112> directions by just changing the silane partial pressure. The lengths as well as the diameters of the wires are precisely controlled by the EBL Au dot patterning and CVD parameters. To predict wire diameters modelling is carried out that takes into account the EBL- and CVD-parameters and describes the observed experimental results very well. Furthermore we were able to create single crystalline Au-dot arrays which are very promising structures for surface enhanced raman spectroscopy (SERS) substrates.

  16. Effect of added silicon carbide nanowires and carbon nanotubes on mechanical properties of 0-3 natural rubber composites

    Science.gov (United States)

    Janyakunmongkol, Khantichai; Nhuapeng, Wim; Thamjaree, Wandee

    2016-01-01

    In this work, the mechanical properties of 0-3 nanocomposite materials containing silicon carbide nanowires (SiCNWs), carbon nanotubes (CNTs), and natural rubber were studied. The SiCNWs and CNTs were used as reinforcement fiber whereas natural rubber was used as the matrix phase. The chemical vapor depositions (CVD) was used for synthesizing the nanowire and nanotube phases. The volume fraction of reinforcement was varied from 0 to 10%. The nanophases were mixed in the natural rubber matrix and molded by the hand lay-up technique. The mechanical properties of the samples were examined and compared with those of neat natural rubber. From the results, it was found that the hardness and density of the samples increased with the quantities of nanophases. The nanocomposites with a volume fraction of 10% exhibited maximum hardness (50.5 SHORE A). The maximum tensile strength and extent of elongation at break of the samples were obtained from the 4% volume fraction sample, which were 16.13 MPa and 1,540%, respectively.

  17. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    International Nuclear Information System (INIS)

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

  18. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    International Nuclear Information System (INIS)

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  19. Development of an autonomous detector for sensing of nerve agents based on functionalized silicon nanowire field-effect transistors.

    Science.gov (United States)

    Clavaguera, Simon; Raoul, Nicolas; Carella, Alexandre; Delalande, Michael; Celle, Caroline; Simonato, Jean-Pierre

    2011-10-15

    The ability to detect minute traces of chemical warfare agents is mandatory both for military forces and homeland security. Various detectors based on different technologies are available but still suffer from serious drawbacks such as false positives. There is still a need for the development of innovative reliable sensors, in particular for organophosphorus nerve agents like Sarin. We report herein on the fabrication of a portable, battery-operated, microprocessor-based prototype sensor system relying on silicon nanowire field-effect transistors for the detection of nerve agents. A fast, supersensitive and highly selective detection of organophosphorus molecules is reported. The results show also high selectivity in complex mixtures and on contaminated materials. PMID:21962681

  20. Comparative Study on Anti-reflection Effect between Porous Silicon and Silicon Nanowires%多孔硅和硅纳米线的减反性能对比研究

    Institute of Scientific and Technical Information of China (English)

    郭萍; 孙凤梅; 张渊; 夏兵

    2012-01-01

    By anode electrochemical etching or wet chemical etching, porous silicon and silicon nanowires were prepared, respectively. After oxidation by air plasma, these two samples were characterized by scanning electron microscope, infrared spectrum. Finally, the antireflection effect of porous silicon and silicon nanowires were measured, which indicated silicon nanowires had better anti-reflection effect.%基于单晶硅材料,通过阳极电化学腐蚀法制得多孔硅材料,通过湿化学刻蚀法制得硅纳米线材料,经过空气等离子体氧化处理后,采用扫描电子显微镜、傅里叶红外光谱仪对样品的化学组分以及表面微观结构进行了表征.最后对多孔硅和硅纳米线材料的减反效果进行对比,结果表明,硅纳米线具有更优越的减反效果.

  1. Low-loss and low-crosstalk 8 × 8 silicon nanowire AWG routers fabricated with CMOS technology.

    Science.gov (United States)

    Wang, Jing; Sheng, Zhen; Li, Le; Pang, Albert; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Qi, Minghao; Gan, Fuwan

    2014-04-21

    Low-loss and low-crosstalk 8 × 8 arrayed waveguide grating (AWG) routers based on silicon nanowire waveguides are reported. A comparative study of the measurement results of the 3.2 nm-channel-spacing AWGs with three different designs is performed to evaluate the effect of each optimal technique, showing that a comprehensive optimization technique is more effective to improve the device performance than a single optimization. Based on the comprehensive optimal design, we further design and experimentally demonstrate a new 8-channel 0.8 nm-channel-spacing silicon AWG router for dense wavelength division multiplexing (DWDM) application with 130 nm CMOS technology. The AWG router with a channel spacing of 3.2 nm (resp. 0.8 nm) exhibits low insertion loss of 2.32 dB (resp. 2.92 dB) and low crosstalk of -20.5~-24.5 dB (resp. -16.9~-17.8 dB). In addition, sophisticated measurements are presented including all-input transmission testing and high-speed WDM system demonstrations for these routers. The functionality of the Si nanowire AWG as a router is characterized and a good cyclic rotation property is demonstrated. Moreover, we test the optical eye diagrams and bit-error-rates (BER) of the de-multiplexed signal when the multi-wavelength high-speed signals are launched into the AWG routers in a system experiment. Clear optical eye diagrams and low power penalty from the system point of view are achieved thanks to the low crosstalk of the AWG devices. PMID:24787827

  2. Proteins as "dopable" bio-electronic materials

    Science.gov (United States)

    Cahen, David

    2013-02-01

    Proteins are surprisingly good solid-state electronic conductors. This holds also for proteins without any known biological electron transfer function. How do they do it? To answer this question we measure solid-state electron transport (ETp) across proteins that are "dry" (only tightly bound water, to retain the conformation, still present). We compare results for the electron transfer (ET) protein, Azurin (Az), the proton-pumping membrane protein Bacteriorhodopsin (bR), and for Human and Bovine Serum Albumin (HSA and BSA). Clear differences between these proteins are seen, which preserve their structure in the solid state measurement configuration. Importantly for future bioelectronics, the results are sensitive to protein modification, e.g., removing or disconnecting the retinal in bR and removing or replacing the Cu redox centre in Az. These cofactors can thus be viewed as natural dopants for proteins. Insight in the ETp mechanism comes from temperature-dependent studies. Az shows 40-360K temperature-independent ETp across its 3.5 nm long axis, until its denaturation temperature, indicative of tunneling. Cu removal, replacement (by Zn) or deuteration changes this to thermally activated ETp. This suggests hopping and involvement of the amide backbone in the ETp. The latter, which rhymes with indications from ETp experiments on oligopeptide and simulations of ET in proteins, opens the way for modeling what otherwise is an awfully complex system. Below 200K all proteins and their variants show temperature-independent ETp. We can furthermore make a totally electrically inactive protein, HSA, into an efficient ETp medium by doping it with natural poly-ene. Putting our data in perspective by comparing them to all known protein ETp data in the literature, we conclude that, in general, proteins are well described as dopable molecular wires.

  3. Application of silicon nanowires and indium tin oxide surfaces in desorption electrospray ionization

    Czech Academy of Sciences Publication Activity Database

    Pól, Jaroslav; Novák, Petr; Volný, Michael; Kruppa, G. H.; Kostiainen, R.; Lemr, Karel; Havlíček, Vladimír

    2008-01-01

    Roč. 14, č. 6 (2008), s. 391-399. ISSN 1469-0667 R&D Projects: GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : mass spectrometry * desorption electrospray ionization * nanowires Subject RIV: CE - Biochemistry Impact factor: 1.167, year: 2008

  4. Synthesis and photoluminescence property of silicon carbide nanowires thin film by HF-PECVD system

    Indian Academy of Sciences (India)

    Zhang Enlei; Wang Guosheng; Long Xiaozhu; Wang Zhumin

    2014-10-01

    A sample and scalable synthetic strategy was developed for the fabrication of nanocrystalline SiC (nc-SiC) thin film. Thin sheet of nanocrystalline diamond was deposited on Si substrate by hot filamentassisted plasma-enhanced chemical vapour deposition system (HF-PECVD). Further, the resulting carbonbased sheet was heated at 1200 °C to allow a solid state reaction between C and Si substrate to form the SiC thin films. The synthesized films mainly consist of -SiC nanowires with diameters of about 50 nm and tens of micrometers long. The nanowires axes lie along the [1 1 1] direction and possess a high density of planar defects. The -SiC nanowires thin films exhibit the strong photoluminescence (PL) peak at a wavelength of 400 nm, which is significantly shifted to the blue compared with the reported PL results of SiC materials. The blue shift may be ascribed to morphology, quantum size confinement effects of the nanomaterials and abundant structure defects that existed in the nanowires.

  5. Nanoscience and the nano-bioelectronics frontier

    OpenAIRE

    Duan, Xiaojie; Lieber, Charles M.

    2015-01-01

    This review describes work presented in the 2014 inaugural Tsinghua University Press-Springer Nano Research Award lecture, as well as current and future opportunities for nanoscience research at the interface with brain science. First, we briefly summarize some of the considerations and the research journey that has led to our focus on bottom-up nanoscale science and technology. Second, we recapitulate the motivation for and our seminal contributions to nanowire-based nanoscience and technolo...

  6. Growing InGaAs quasi-quantum wires inside semi-rhombic shaped planar InP nanowires on exact (001) silicon

    Science.gov (United States)

    Han, Yu; Li, Qiang; Chang, Shih-Pang; Hsu, Wen-Da; Lau, Kei May

    2016-06-01

    We report InGaAs quasi-quantum wires embedded in planar InP nanowires grown on (001) silicon emitting in the 1550 nm communication band. An array of highly ordered InP nanowire with semi-rhombic cross-section was obtained in pre-defined silicon V-grooves through selective-area hetero-epitaxy. The 8% lattice mismatch between InP and Si was accommodated by an ultra-thin stacking disordered InP/GaAs nucleation layer. X-ray diffraction and transmission electron microscope characterizations suggest excellent crystalline quality of the nanowires. By exploiting the morphological evolution of the InP and a self-limiting growth process in the V-grooves, we grew embedded InGaAs quantum-wells and quasi-quantum-wires with tunable shape and position. Room temperature analysis reveals substantially improved photoluminescence in the quasi-quantum wires as compared to the quantum-well reference, due to the reduced intrusion defects and enhanced quantum confinement. These results show great promise for integration of III-V based long wavelength nanowire lasers on the well-established (001) Si platform.

  7. Ordered silicon nanowire arrays prepared by an improved nanospheres self-assembly in combination with Ag-assisted wet chemical etching

    Science.gov (United States)

    Jia, Guobin; Westphalen, Jasper; Drexler, Jan; Plentz, Jonathan; Dellith, Jan; Dellith, Andrea; Andrä, Gudrun; Falk, Fritz

    2016-04-01

    An improved Langmuir-Blodgett self-assembly process combined with Ag-assisted wet chemical etching for the preparation of ordered silicon nanowire arrays is presented in this paper. The new process is independent of the surface conditions (hydrophilic or hydrophobic) of the substrate, allowing for depositing a monolayer of closely packed polystyrene nanospheres onto any flat surface. A full control of the morphology of the silicon nanowire is achieved. Furthermore, it is observed that the formation of porous-Si at the tips of the nanowires is closely related to the release of Ag nanoparticles from the Ag mask during the etching, which subsequently redeposit on the surface initially free of Ag, and these Ag nanoparticles catalyze the etching of the tips and lead to the porous-Si formation. This finding will help to improve the resulting nano- and microstructures to get them free of pores, and renders it a promising technology for low-cost high throughput fabrication of specific optical devices, photonic crystals, sensors, MEMS, and NEMS by substituting the costly BOSCH process. It is shown that ordered nanowire arrays free of porous structures can be produced if all sources of Ag nanoparticles are excluded, and structures with aspect ratio more than 100 can be produced.

  8. Mechanical properties of silicon nanowire anodes at different states of charge

    OpenAIRE

    Moenig, Reiner

    2014-01-01

    Silicon is considered to be a promising anode material for lithium-ion batteries with very high energy densities. During lithiation, silicon anodes form different Li–Si phases and store up to 3.75 lithium ions per silicon atom. Associated with this high capacity is a volume change of roughly 300% and large mechanical stresses that may affect the electrochemical processes. The stresses that actually form strongly depend on the mechanical properties of the lithium silicides and the mechanical p...

  9. Optical waveform sampling and error-free demultiplexing of 1.28 Tbit/s serial data in a silicon nanowire

    DEFF Research Database (Denmark)

    Ji, Hua; Hu, Hao; Galili, Michael; Oxenløwe, Leif Katsuo; Pu, Minhao; Yvind, Kresten; Hvam, Jørn Märcher; Jeppesen, Palle

    We experimentally demonstrate 640 Gbit/s and 1.28 Tbit/s serial data optical waveform sampling and 640-to-10 Gbit/s and 1.28 Tbit/s-to-10 Gbit/s error-free demultiplexing using four-wave mixing in a 300nm$$450nm$$5mm silicon nanowire.......We experimentally demonstrate 640 Gbit/s and 1.28 Tbit/s serial data optical waveform sampling and 640-to-10 Gbit/s and 1.28 Tbit/s-to-10 Gbit/s error-free demultiplexing using four-wave mixing in a 300nm$$450nm$$5mm silicon nanowire....

  10. Flat-topped and low loss silicon-nanowire-type optical MUX/DeMUX employing multi-stage microring resonator assisted delayed Mach-Zehnder interferometers.

    Science.gov (United States)

    Jeong, Seok-Hwan; Tanaka, Shinsuke; Akiyama, Tomoyuki; Sekiguchi, Shigeaki; Tanaka, Yu; Morito, Ken

    2012-11-01

    We propose a novel silicon-nanowire-type multiplexer (MUX) / demultiplexer (DeMUX) based on multi-stage microring resonator assisted delayed Mach-Zehnder interferometers. It is theoretically shown that spectral flatness of DeMUX spectra can be accomplished by incorporating nonlinear phase behaviors of microring resonators into the multi-stage delayed Mach-Zehnder interferometers. We experimentally demonstrate flat-topped 400GHz-spacing 1 × 4Ch demultiplexing operation in the fabricated device with silicon-nanowire waveguides. Furthermore, by integrating the micro-heaters on the top cladding layer of the fabricated device, the DeMUX performance is upgraded in terms of excess loss (flatness at each channel grid. PMID:23187415

  11. Surface chemistry and morphology of the solid electrolyte interphase on silicon nanowire lithium-ion battery anodes

    KAUST Repository

    Chan, Candace K.

    2009-04-01

    Silicon nanowires (SiNWs) have the potential to perform as anodes for lithium-ion batteries with a much higher energy density than graphite. However, there has been little work in understanding the surface chemistry of the solid electrolyte interphase (SEI) formed on silicon due to the reduction of the electrolyte. Given that a good, passivating SEI layer plays such a crucial role in graphite anodes, we have characterized the surface composition and morphology of the SEI formed on the SiNWs using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). We have found that the SEI is composed of reduction products similar to that found on graphite electrodes, with Li2CO3 as an important component. Combined with electrochemical impedance spectroscopy, the results were used to determine the optimal cycling parameters for good cycling. The role of the native SiO2 as well as the effect of the surface area of the SiNWs on reactivity with the electrolyte were also addressed. © 2009 Elsevier B.V. All rights reserved.

  12. Silicon nanowire-based ring-shaped tri-axial force sensor for smart integration on guidewire

    Science.gov (United States)

    Han, Beibei; Yoon, Yong-Jin; Hamidullah, Muhammad; Tsu-Hui Lin, Angel; Park, Woo-Tae

    2014-06-01

    A ring-shaped tri-axial force sensor with a 200 µm × 200 µm sensor area using silicon nanowires (SiNWs) as piezoresistive sensing elements is developed and characterized. The sensor comprises a suspended ring structure located at the center of four suspended beams that can be integrated on the distal tip of a guidewire by passing through the hollow core of the sensor. SiNWs with a length of 6 µm and a cross section of 90 nm × 90 nm are embedded at the anchor of each silicon bridge along direction as the piezoresistive sensing element. Finite element analysis has been used to determine the location of maximum stress and the simulation results are verified with the experimental measurements. Taking advantage of the high sensitivity of SiNWs, the fabricated ring-shaped sensor is capable of detecting small displacement in nanometer ranges with a sensitivity of 13.4 × 10-3 µm-1 in the z-direction. This tri-axial force sensor also shows high linearity (>99.9%) to the applied load and no obvious hysteresis is observed. The developed SiNW-based tri-axial force sensor provides new opportunities to implement sensing capability on medical instruments such as guidewires and robotic surgical grippers, where ultra-miniaturization and high sensitivity are essential.

  13. Vertical Silicon Nanowire Platform for Low Power Electronics and Clean Energy Applications

    Directory of Open Access Journals (Sweden)

    D.-L. Kwong

    2012-01-01

    Full Text Available This paper reviews the progress of the vertical top-down nanowire technology platform developed to explore novel device architectures and integration schemes for green electronics and clean energy applications. Under electronics domain, besides having ultimate scaling potential, the vertical wire offers (1 CMOS circuits with much smaller foot print as compared to planar transistor at the same technology node, (2 a natural platform for tunneling FETs, and (3 a route to fabricate stacked nonvolatile memory cells. Under clean energy harvesting area, vertical wires could provide (1 cost reduction in photovoltaic energy conversion through enhanced light trapping and (2 a fully CMOS compatible thermoelectric engine converting waste-heat into electricity. In addition to progress review, we discuss the challenges and future prospects with vertical nanowires platform.

  14. Hierarchical silicon nanowires-carbon textiles matrix as a binder-free anode for high-performance advanced lithium-ion batteries

    OpenAIRE

    Liu, Bin; Wang, Xianfu; Chen, Haitian; Wang, Zhuoran; Chen, Di; Cheng, Yi-Bing; Zhou, Chongwu; Shen, Guozhen

    2013-01-01

    Toward the increasing demands of portable energy storage and electric vehicle applications, the widely used graphite anodes with significant drawbacks become more and more unsuitable. Herein, we report a novel scaffold of hierarchical silicon nanowires-carbon textiles anodes fabricated via a facile method. Further, complete lithium-ion batteries based on Si and commercial LiCoO2 materials were assembled to investigate their corresponding across-the-aboard performances, demonstrating their enh...

  15. 硅纳米线阵列的制备及光伏性能%Preparation and Photovoltaic Properties of Silicon Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    蒋玉荣; 秦瑞平; 蔡方敏; 杨海刚; 马恒; 常方高

    2013-01-01

    在常温常压下,采用无电极金属催化化学腐蚀法在P型单晶硅片(100)基底上制备定向排列的硅纳米线阵列.研究了不同浓度硝酸银对纳米线阵列形貌、反射光谱性能的影响和具有电池雏形的硅纳米线阵列的光伏性能.结果表明:硝酸银浓度在0.02 mol/L时为最佳配比;与普通绒面电池相比,硅纳米线阵列太阳能电池的光电转换性能明显优于普通绒面电池.用光谱响应分析手段分析硅纳米线电池光伏性能的影响因素,并提出解决办法.%Large area aligned identical silicon nanowires array was prepared on mono-crystalline p-Si(100) wafers via the metal-assisted electroless etching at room temperature, 1.01 × 105Pa, The morphologies and reflection spectra of the samples prepared at different nitric acid silver concentrations were analyzed. In addition, the photovoltaic performance of solar cell silicon based on the nanowires array was investigated. The results show that the optimal concentration of nitric acid silver concentration is 0.02 mol/L. The photoelectric conversion property of solar cells based on the silicon nanowire arrays were better than that of the ordinary texturing solar cell. The photovoltaic performance of silicon nanowires array was also analyzed via the spectral response of different wavelengths.

  16. Vertical Silicon Nanowire Platform for Low Power Electronics and Clean Energy Applications

    OpenAIRE

    D.-L. Kwong; Li, X; Sun, Y.(Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama, 35487, U.S.A.); Ramanathan, G.; Chen, Z. X.; Wong, S M; Li, Y; Shen, N. S.; K. Buddharaju; Yu, Y H; van der Lee, S. J.; Singh, N; Lo, G.Q.

    2012-01-01

    This paper reviews the progress of the vertical top-down nanowire technology platform developed to explore novel device architectures and integration schemes for green electronics and clean energy applications. Under electronics domain, besides having ultimate scaling potential, the vertical wire offers (1) CMOS circuits with much smaller foot print as compared to planar transistor at the same technology node, (2) a natural platform for tunneling FETs, and (3) a route to fabricate stacked non...

  17. First Principles Studies of Tapered Silicon Nanowires: Fundamental Insights and Practical Applications

    Science.gov (United States)

    Wu, Zhigang

    2008-03-01

    Nanowires (NWs) are often observed experimentally to be tapered rather than straight-edged, with diameters (d) shrinking by as much as 1 nm per 10 nm of vertical growth. Previous theoretical studies have examined the electronic properties of straight-edged nanowires (SNWs), although the effects of tapering on quantum confinement may be of both fundamental and practical importance. We have employed ab initio calculations to study the structural and electronic properties of tapered Si NWs. As one may expect, tapered nanowires (TNWs) possess axially-dependent electronic properties; their local energy gaps vary along the wire axis, with the largest gap occurring at the narrowest point of the wire. In contrast to SNWs, where confinement tends to shift valence bands more than conduction bands away from the bulk gap, the unoccupied states in TNWs are much more sensitive to d than the occupied states. In addition, tapering causes the band-edge states to be spatially separated along the wire axis, a consequence of the interplay between a strong variation in quantum confinement strength with diameter and the tapering-induced charge transfer. This property may be exploited in electronic and optical applications, for example, in photovoltaic devices where the separation of the valence and conduction band states could be used to transport excited charges during the thermalization process. In order to gain insight into TNW photovoltaic properties, we have also carried out calculations of the dipole matrix elements near the band edges as well as the role of metal contacts on TNW electronic properties. Finally, a combination of ab initio total energy calculations and classical molecular dynamics (MD) simulations are employed to suggest a new technique for bringing nanoscale objects together to form ordered, ultra high-aspect ratio nanowires. This work was supported in part by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  18. Suppression of the vapor-liquid-solid growth of silicon nanowires by antimony addition.

    Science.gov (United States)

    Nimmatoori, Pramod; Zhang, Qi; Dickey, Elizabeth C; Redwing, Joan M

    2009-01-14

    The effect of Sb addition on the growth rate and structural properties of Si nanowires synthesized by vapor-liquid-solid growth was investigated. The nanowire growth rate was reduced by an order of magnitude following the addition of a low concentration pulse of trimethylantimony (TMSb) to the gas phase during growth. Transmission electron microscopy analysis revealed that the wires had a thick amorphous coating ( approximately 8 nm) around the catalyst particle and a distorted catalyst shape. Energy-dispersive x-ray spectroscopy showed the presence of trace amounts of Sb in the amorphous coating around the catalyst and at the catalyst-wire interface. Antimony was also found to be incorporated in the Si nanowires with a peak in the Sb concentration measured at the initial point where the TMSb pulse was added to the gas stream. The significant reduction in wire growth rate was attributed to Sb segregation at the vapor-liquid and liquid-solid interfaces which results in a change in interfacial energies and a reduction in the rate of Si incorporation at these interfaces. PMID:19417276

  19. Biosensors and bioelectronics on smartphone for portable biochemical detection.

    Science.gov (United States)

    Zhang, Diming; Liu, Qingjun

    2016-01-15

    Smartphone has been widely integrated with sensors, such as test strips, sensor chips, and hand-held detectors, for biochemical detections due to its portability and ubiquitous availability. Utilizing built-in function modules, smartphone is often employed as controller, analyzer, and displayer for rapid, real-time, and point-of-care monitoring, which can significantly simplify design and reduce cost of the detecting systems. This paper presents a review of biosensors and bioelectronics on smartphone for portable biochemical detections. The biosensors and bioelectronics based on smartphone can mainly be classified into biosensors using optics, surface plasmon resonance, electrochemistry, and near-field communication. The developments of these biosensors and bioelectronics on smartphone are reviewed along with typical biochemical detecting cases. Sensor strategies, detector attachments, and coupling methods are highlighted to show designs of the compact, lightweight, and low-cost sensor systems. The performances and advantages of these designs are introduced with their applications in healthcare diagnosis, environment monitoring, and food evaluation. With advances in micro-manufacture, sensor technology, and miniaturized electronics, biosensor and bioelectronic devices on smartphone can be used to perform biochemical detections as common and convenient as electronic tag readout in foreseeable future. PMID:26319170

  20. Fine-tuning of catalytic tin nanoparticles by the reverse micelle method for direct deposition of silicon nanowires by a plasma-enhanced chemical vapour technique.

    Science.gov (United States)

    Poinern, Gérrard E J; Ng, Yan-Jing; Fawcett, Derek

    2010-12-15

    The reverse micelle method was used for the reduction of a tin (Sn) salt solution to produce metallic Sn nanoparticles ranging from 85 nm to 140 nm in diameter. The reverse micellar system used in this process was hexane-butanol-cetyl trimethylammonium bromide (CTAB). The diameters of the Sn nanoparticles were proportional to the concentration of the aqueous Sn salt solution. Thus, the size of the Sn nanoparticles can easily be controlled, enabling a simple, reproducible mechanism for the growth of silicon nanowires (SiNWs) using plasma-enhanced chemical vapour deposition (PECVD). Both the Sn nanoparticles and silicon nanowires were characterised using field-emission scanning electron microscopy (FE-SEM). Further characterisations of the SiNW's were made using transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In addition, dynamic light scattering (DLS) was used to investigate particle size distributions. This procedure demonstrates an economical route for manufacturing reproducible silicon nanowires using fine-tuned Sn nanoparticles for possible solar cell applications. PMID:20887996

  1. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes

    Science.gov (United States)

    Kim, Junhee; Jung, Cho-Long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-Seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-03-01

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I-/I3- was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode.To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the

  2. Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors

    Directory of Open Access Journals (Sweden)

    Tomi Roinila

    2014-07-01

    Full Text Available Silicon nanowire-based field-effect transistors (SiNW FETs have demonstrated the ability of ultrasensitive detection of a wide range of biological and chemical targets. The detection is based on the variation of the conductance of a nanowire channel, which is caused by the target substance. This is seen in the voltage–current behavior between the drain and source. Some current, known as leakage current, flows between the gate and drain, and affects the current between the drain and source. Studies have shown that leakage current is frequency dependent. Measurements of such frequency characteristics can provide valuable tools in validating the functionality of the used transistor. The measurements can also be an advantage in developing new detection technologies utilizing SiNW FETs. The frequency-domain responses can be measured by using a commercial sine-sweep-based network analyzer. However, because the analyzer takes a long time, it effectively prevents the development of most practical applications. Another problem with the method is that in order to produce sinusoids the signal generator has to cope with a large number of signal levels. This may become challenging in developing low-cost applications. This paper presents fast, cost-effective frequency-domain methods with which to obtain the responses within seconds. The inverse-repeat binary sequence (IRS is applied and the admittance spectroscopy between the drain and source is computed through Fourier methods. The methods is verified by experimental measurements from an n-type SiNW FET.

  3. First principles simulation of amorphous silicon bulk, interfaces, and nanowires for photovoltaics

    OpenAIRE

    Belayneh, Merid Legesse

    2015-01-01

    Amorphous silicon has become the material of choice for many technologies, with major applications in large area electronics: displays, image sensing and thin film photovoltaic cells. This technology development has occurred because amorphous silicon is a thin film semiconductor that can be deposited on large, low cost substrates using low temperature. In this thesis, classical molecular dynamics and first principles DFT calculations have been performed to generate structural models of amorph...

  4. Electroless selective deposition of gold nano-array for silicon nanowires growth

    Directory of Open Access Journals (Sweden)

    Ruiz-Gomes E.

    2014-01-01

    Full Text Available Nanopatterns of gold clusters on a large surface of oriented Si(111 substrates, from the galvanic displacement of gold salt (via the spontaneous reduction of AuCl4 -, are demonstrated in this work. The Si substrate is patterned by Focused Ion Beam (FIB prior to being dipped in a gold solution. Here, we show that these patterns lead to successful control of the position and size of gold clusters. Sequential patterning reveals a powerful maskless alternative to surface preparation prior to Si nanowire growth

  5. Bandstructure and mobility variations in p-type Silicon nanowires under electrostatic gate field

    OpenAIRE

    Neophytou, Neophytos; Baumgartner, Oskar; Stanojevic, Zlatan; Kosina, Hans

    2013-01-01

    The sp3d5s*-spin-orbit-coupled atomistic tight-binding (TB) model is used for the electronic structure calculation of Si nanowires (NWs), self consistently coupled to a 2D Poisson equation, solved in the cross section of the NW. Upon convergence, the linearized Boltzmann transport theory is employed for the mobility calculation, including carrier scattering by phonons and surface roughness. As the channel is driven into inversion, for [111] and [110] NW devices of diameters D>10nm the curvatu...

  6. High performance ring oscillators from 10-nm wide silicon nanowire field-effect transistors

    KAUST Repository

    Huang, Ruo-Gu

    2011-06-24

    We explore 10-nm wide Si nanowire (SiNW) field-effect transistors (FETs) for logic applications, via the fabrication and testing of SiNW-based ring oscillators. We report on SiNW surface treatments and dielectric annealing, for producing SiNW FETs that exhibit high performance in terms of large on/off-state current ratio (~108), low drain-induced barrier lowering (~30 mV) and low subthreshold swing (~80 mV/decade). The performance of inverter and ring-oscillator circuits fabricated from these nanowire FETs are also explored. The inverter demonstrates the highest voltage gain (~148) reported for a SiNW-based NOT gate, and the ring oscillator exhibits near rail-to-rail oscillation centered at 13.4 MHz. The static and dynamic characteristics of these NW devices indicate that these SiNW-based FET circuits are excellent candidates for various high-performance nanoelectronic applications. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  7. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    Science.gov (United States)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

    2015-12-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

  8. Synthesis and optical property of large-scale centimetres-long silicon carbide nanowires by catalyst-free CVD route under superatmospheric pressure conditions.

    Science.gov (United States)

    Lin, Liangwu

    2011-04-01

    Large-scale centimetres-long single-crystal β-SiC nanowires have been prepared using CH(4) as the carbon source and SiO or the mixture of Si and SiO(2) as the silicon source by a simple catalyst-free CVD route under superatmospheric pressure conditions. The nanowries grown on ceramic boat or corundum substrates, with lengths of several centimetres and the average diameters of around 40 nm, were composed of single-crystal β-SiC core along the [111] direction and amorphous SiO(2) shell of about 1-30 nm thick depending on the growth position along the flowing direction of the carrier gas. The total gas pressure is an important factor for the synthesis of the large-scale centimetres-long β-SiC nanowires, which can easily adjust the pressure of the vapors to supersaturation condition. The growth of the nanowires was governed by the Vapor-Solid mechanism. The β-SiC nanowires showed an intense blue light emission at room temperature. PMID:21305091

  9. Silicon nanowire-based ring-shaped tri-axial force sensor for smart integration on guidewire

    International Nuclear Information System (INIS)

    A ring-shaped tri-axial force sensor with a 200 µm × 200 µm sensor area using silicon nanowires (SiNWs) as piezoresistive sensing elements is developed and characterized. The sensor comprises a suspended ring structure located at the center of four suspended beams that can be integrated on the distal tip of a guidewire by passing through the hollow core of the sensor. SiNWs with a length of 6 µm and a cross section of 90 nm × 90 nm are embedded at the anchor of each silicon bridge along 〈1 1 0〉 direction as the piezoresistive sensing element. Finite element analysis has been used to determine the location of maximum stress and the simulation results are verified with the experimental measurements. Taking advantage of the high sensitivity of SiNWs, the fabricated ring-shaped sensor is capable of detecting small displacement in nanometer ranges with a sensitivity of 13.4 × 10−3 µm−1 in the z-direction. This tri-axial force sensor also shows high linearity (>99.9%) to the applied load and no obvious hysteresis is observed. The developed SiNW-based tri-axial force sensor provides new opportunities to implement sensing capability on medical instruments such as guidewires and robotic surgical grippers, where ultra-miniaturization and high sensitivity are essential. (paper)

  10. Pseudopotential-based electron quantum transport: Theoretical formulation and application to nanometer-scale silicon nanowire transistors

    Science.gov (United States)

    Fang, Jingtian; Vandenberghe, William G.; Fu, Bo; Fischetti, Massimo V.

    2016-01-01

    We present a formalism to treat quantum electronic transport at the nanometer scale based on empirical pseudopotentials. This formalism offers explicit atomistic wavefunctions and an accurate band structure, enabling a detailed study of the characteristics of devices with a nanometer-scale channel and body. Assuming externally applied potentials that change slowly along the electron-transport direction, we invoke the envelope-wavefunction approximation to apply the open boundary conditions and to develop the transport equations. We construct the full-band open boundary conditions (self-energies of device contacts) from the complex band structure of the contacts. We solve the transport equations and present the expressions required to calculate the device characteristics, such as device current and charge density. We apply this formalism to study ballistic transport in a gate-all-around (GAA) silicon nanowire field-effect transistor with a body-size of 0.39 nm, a gate length of 6.52 nm, and an effective oxide thickness of 0.43 nm. Simulation results show that this device exhibits a subthreshold slope (SS) of ˜66 mV/decade and a drain-induced barrier-lowering of ˜2.5 mV/V. Our theoretical calculations predict that low-dimensionality channels in a 3D GAA architecture are able to meet the performance requirements of future devices in terms of SS swing and electrostatic control.

  11. Highly Disordered Array of Silicon Nanowires: an Effective and Scalable Approach for Performing and Flexible Electrochemical Biosensors.

    Science.gov (United States)

    Maiolo, Luca; Polese, Davide; Pecora, Alessandro; Fortunato, Guglielmo; Shacham-Diamand, Yosi; Convertino, Annalisa

    2016-03-01

    The direct integration of disordered arranged and randomly oriented silicon nanowires (SiNWs) into ultraflexible and transferable electronic circuits for electrochemical biosensing applications is proposed. The working electrode (WE) of a three-electrode impedance device, fabricated on a polyimide (PI) film, is modified with SiNWs covered by a thin Au layer and functionalized to bind the sensing element. The biosensing behavior is investigated through the ligand-receptor binding of biotin-avidin system. Impedance measurements show a very efficient detection of the avidin over a broad range of concentrations from hundreds of micromolar down to the picomolar values. The impedance response is modeled through a simple equivalent circuit, which takes into account the unique WE morphology and its modification with successive layers of biomolecules. This approach of exploiting highly disordered SiNW ensemble in biosensing proves to be very promising for the following three main reasons: first, the system morphology allows high sensing performance; second, these nanostructures can be built via scalable and transferable fabrication methodology allowing an easy integration on non-conventional substrates; third, reliable modeling of the sensing response can be developed by considering the morphological and surface characteristics over an ensemble of disordered NWs rather than over individual NWs. PMID:26717420

  12. Formation of Silicon/Carbon Core-Shell Nanowires Using Carbon Nitride Nanorods Template and Gold Catalyst

    Directory of Open Access Journals (Sweden)

    Ilyani Putri Jamal

    2013-01-01

    Full Text Available In this experiment, silicon/carbon (Si/C core-shell nanowires (NWs were synthesized using gold nanoparticles (Au NPs coated carbon nitride nanorods (CN NRs as a template. To begin with, the Au NPs coated CN NRs were prepared by using plasma-enhanced chemical vapor deposition assisted with hot-wire evaporation technique. Fourier transform infrared spectrum confirms the C–N bonding of the CN NRs, while X-ray diffraction pattern indicates the crystalline structure of the Au NPs and amorphous structure of the CN NRs. The Au NPs coated CN NRs were thermally annealed at temperature of 800°C in nitrogen ambient for one hour to induce the growth of Si/C core-shell NWs. The growth mechanism for the Si/C core-shell NWs is related to the nitrogen evolution and solid-liquid-solid growth process which is a result of the thermal annealing. The formation of Si/C core-shell NWs is confirmed by electron spectroscopic imaging analysis.

  13. Pseudopotential-based electron quantum transport: Theoretical formulation and application to nanometer-scale silicon nanowire transistors

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Jingtian, E-mail: jingtian.fang@utdallas.edu; Vandenberghe, William G.; Fu, Bo; Fischetti, Massimo V. [Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080 (United States)

    2016-01-21

    We present a formalism to treat quantum electronic transport at the nanometer scale based on empirical pseudopotentials. This formalism offers explicit atomistic wavefunctions and an accurate band structure, enabling a detailed study of the characteristics of devices with a nanometer-scale channel and body. Assuming externally applied potentials that change slowly along the electron-transport direction, we invoke the envelope-wavefunction approximation to apply the open boundary conditions and to develop the transport equations. We construct the full-band open boundary conditions (self-energies of device contacts) from the complex band structure of the contacts. We solve the transport equations and present the expressions required to calculate the device characteristics, such as device current and charge density. We apply this formalism to study ballistic transport in a gate-all-around (GAA) silicon nanowire field-effect transistor with a body-size of 0.39 nm, a gate length of 6.52 nm, and an effective oxide thickness of 0.43 nm. Simulation results show that this device exhibits a subthreshold slope (SS) of ∼66 mV/decade and a drain-induced barrier-lowering of ∼2.5 mV/V. Our theoretical calculations predict that low-dimensionality channels in a 3D GAA architecture are able to meet the performance requirements of future devices in terms of SS swing and electrostatic control.

  14. Molecular layer deposition of APTES on silicon nanowire biosensors: Surface characterization, stability and pH response

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: We report the use of molecular layer deposition (MLD) for depositing 3-aminopropyltriethoxysilane (APTES) on a silicon dioxide surface. The APTES monolayer was characterized using spectroscopic ellipsometry, contact angle goniometry, and atomic force microscopy. Effects of reaction time of repeating pulses and simultaneous feeding of water vapor with APTES were tested. The results indicate that the synergistic effects of water vapor and reaction time are significant for the formation of a stable monolayer. Additionally, increasing the number of repeating pulses improved the APTES surface coverage but led to saturation after 10 pulses. In comparing MLD with solution-phase deposition, the APTES surface coverage and the surface quality were nearly equivalent. The hydrolytic stability of the resulting films was also studied. The results confirmed that the hydrolysis process was necessary for MLD to obtain stable surface chemistry. Furthermore, we compared the pH sensing results of Si nanowire field effect transistors (Si NWFETs) modified by both the MLD and solution methods. The highly repeatable pH sensing results reflected the stability of APTES monolayers. The results also showed an improved pH response of the sensor prepared by MLD compared to the one prepared by the solution treatment, which indicated higher surface coverage of APTES

  15. CMOS-compatible, label-free silicon-nanowire biosensors to detect cardiac troponin I for acute myocardial infarction diagnosis.

    Science.gov (United States)

    Kong, Tao; Su, Ruigong; Zhang, Beibei; Zhang, Qi; Cheng, Guosheng

    2012-04-15

    A label-free biosensor for electrical detection of cardiac troponin I (cTnI), a highly sensitive and selective biomarker of acute myocardial infarction (AMI), is demonstrated using silicon nanowire (SiNW) based field-effect transistors (FETs). The FET devices were fabricated by a complementary metal oxide semiconductor (CMOS) compatible top-down approach to define the SiNW followed by tetramethylammonium hydroxide (TMAH) wet etching. Electrical characterizations of the SiNW FET revealed an ambipolar conduction characteristic with an on/off ratio of 10(5)-10(6). CTnI monoclonal antibodies were then covalently immobilized on the SiNW surfaces. By integrating with a homemade biosensor measurement system, the biosensor exhibited rapid and sensitive response to cTnI proteins. The current response showed a nature of logarithm relationship against the cTnI concentration from 46 ng/mL down to 0.092 ng/mL. Moreover, an anti-interference capability of the fabricated biosensor was also assessed. By utilizing the top-down fabrication method, this work provides an efficient way for the cTnI proteins detection with an enormous potential of mass-production, which definitely facilitate the practical applications. PMID:22386490

  16. Silicon nanowire and carbon nanotube hybrid for room temperature multiwavelength light source.

    Science.gov (United States)

    Lo Faro, Maria Josè; D'Andrea, Cristiano; Messina, Elena; Fazio, Barbara; Musumeci, Paolo; Reitano, Riccardo; Franzò, Giorgia; Gucciardi, Pietro Giuseppe; Vasi, Cirino; Priolo, Francesco; Iacona, Fabio; Irrera, Alessia

    2015-01-01

    The realization of an innovative hybrid light source operating at room temperature, obtained by embedding a carbon nanotube (CNT) dispersion inside a Si nanowire (NW) array is reported. The NW/CNT system exhibits a peculiar photoluminescence spectrum, consisting of a wide peak, mainly observed in the visible range, due to quantum confined Si NWs, and of several narrower IR peaks, due to the different CNT chiralities present in the dispersion. The detailed study of the optical properties of the hybrid system evidences that the ratio between the intensity of the visible and the IR emissions can be varied within a wide range by changing the excitation wavelength or the CNT concentration; the conditions leading to the prevalence of one signal with respect to the other are identified. The multiplicity of emission spectra obtainable from this composite material opens new perspectives for Si nanostructures as active medium in light sources for Si photonics applications. PMID:26592198

  17. Silicon nanowire array/polymer hybrid solar cell incorporating carbon nanotubes

    International Nuclear Information System (INIS)

    Here we present a simple and novel approach of fabricating three dimensional (3D) n-Si nanowires (NWs) and poly(3-octylthiophene) hybrid solar cells incorporating carbon nanotubes (CNTs). Vertically aligned n-Si NWs arrays were fabricated by electroless chemical etching of a n-Si [1 1 1] wafer. n-Si NWs/poly(3-octylthiophene) hybrid solar cells were fabricated with and without functionalized CNTs incorporation. Fabricated solar cells incorporating CNTs show open circuit voltage (Voc), short circuit current density (Jsc) fill factor (FF) and conversion efficiency as 0.353, 7.85 mA cm-2, 22% and 0.61%, respectively. In fabricated devices n-Si NWs arrays form multiple heterojunctions with the polymer and provide efficient electron collection and transportation, whereas CNTs provide efficient hole transportation.

  18. Silicon nanowire arrays coated with electroless Ag for increased surface-enhanced Raman scattering

    Science.gov (United States)

    Bai, Fan; Li, Meicheng; Fu, Pengfei; Li, Ruike; Gu, Tiansheng; Huang, Rui; Chen, Zhao; Jiang, Bing; Li, Yingfeng

    2015-05-01

    The ordered Ag nanorod (AgNR) arrays are fabricated through a simple electroless deposition technique using the isolated Si nanowire (SiNW) arrays as the Ag-grown scaffold. The AgNR arrays have the single-crystallized structure and the plasmonic crystal feature. It is found that the formation of the AgNR arrays is strongly dependent on the filling ratio of SiNWs. A mechanism is proposed based on the selective nucleation and the synergistic growth of Ag nanoparticles on the top of the SiNWs. Moreover, the special AgNR arrays grown on the substrate of SiNWs exhibit a detection sensitivity of 10-15M for rhodamine 6G molecules, which have the potential application to the highly sensitive surface-enhanced Raman scattering sensors.

  19. Silicon nanowire arrays coated with electroless Ag for increased surface-enhanced Raman scattering

    Directory of Open Access Journals (Sweden)

    Fan Bai

    2015-05-01

    Full Text Available The ordered Ag nanorod (AgNR arrays are fabricated through a simple electroless deposition technique using the isolated Si nanowire (SiNW arrays as the Ag-grown scaffold. The AgNR arrays have the single-crystallized structure and the plasmonic crystal feature. It is found that the formation of the AgNR arrays is strongly dependent on the filling ratio of SiNWs. A mechanism is proposed based on the selective nucleation and the synergistic growth of Ag nanoparticles on the top of the SiNWs. Moreover, the special AgNR arrays grown on the substrate of SiNWs exhibit a detection sensitivity of 10−15M for rhodamine 6G molecules, which have the potential application to the highly sensitive surface-enhanced Raman scattering sensors.

  20. Development of a Bioelectronic Tongue -Applications for Wastewater Analysis

    OpenAIRE

    Dock, Eva

    2006-01-01

    A bioelectronic tongue has been developed for applications in wastewater analysis. The development of a biosensor array with complex signal analysis started from the idea of using group-selective phenol biosensors (tyrosinase and horseradish peroxidase) with chemometric analysis for signal processing. In a first step the ability to simultaneously determine each analyte in synthetic binary phenol mixtures was evaluated using multivariate data analysis on the responses from a single tyrosinase-...

  1. Nanowires of silicon carbide and 3D SiC/C nanocomposites with inverse opal structure

    International Nuclear Information System (INIS)

    Synthesis, morphology, structural and optical characteristics of SiC NWs and SiC/C nanocomposites with an inverse opal lattice have been investigated. The samples were prepared by carbothermal reduction of silica (SiC NWs) and by thermo-chemical treatment of opal matrices (SiC/C) filled with carbon compounds which was followed by silicon dioxide dissolution. It was shown that the nucleation of SiC NWs occurs at the surface of carbon fibers felt. It was observed three preferred growth direction of the NWs: [111], [110] and [112]. HRTEM studies revealed the mechanism of the wires growth direction change. SiC/C- HRTEM revealed in the structure of the composites, except for silicon carbide, graphite and amorphous carbon, spherical carbon particles containing concentric graphite shells (onion-like particles).

  2. Thin Film Silicon Nanowire/PEDOT:PSS Hybrid Solar Cells with Surface Treatment.

    Science.gov (United States)

    Wang, Hao; Wang, Jianxiong; Hong, Lei; Tan, Yew Heng; Tan, Chuan Seng; Rusli

    2016-12-01

    SiNW/PEDOT:PSS hybrid solar cells are fabricated on 10.6-μm-thick crystalline Si thin films. Cells with Si nanowires (SiNWs) of different lengths fabricated using the metal-catalyzed electroless etching (MCEE) technique have been investigated. A surface treatment process using oxygen plasma has been applied to improve the surface quality of the SiNWs, and the optimized cell with 0.7-μm-long SiNWs achieved a power conversion efficiency (PCE) of 7.83 %. The surface treatment process is found to remove surface defects and passivate the SiNWs and substantially improve the average open circuit voltage from 0.461 to 0.562 V for the optimized cell. The light harvesting capability of the SiNWs has also been investigated theoretically using optical simulation. It is found that the inherent randomness of the MCEE SiNWs, in terms of their diameter and spacing, accounts for the excellent light harvesting capability. In comparison, periodic SiNWs of comparable dimensions have been shown to exhibit much poorer trapping and absorption of light. PMID:27356558

  3. Applying contact to individual silicon nanowires using a dielectrophoresis (DEP)-based technique

    International Nuclear Information System (INIS)

    One major challenge for the technological use of nanostructures is the control of their electrical and optoelectronic properties. For that purpose, extensive research into the electrical characterization and therefore a fast and reliable way of contacting these structures are needed. Here, we report on a new, dielectrophoresis (DEP)-based technique, which enables to apply sufficient and reliable contact to individual nanostructures, like semiconducting nanowires (NW), easily and without the need for lithography. The DEP contacting technique presented in this article can be done without high-tech equipment and monitored in situ with an optical microscope. In the presented experiments, individual SiNWs are trapped and subsequently welded between two photolithographically pre-patterned electrodes by applying varying AC voltages to the electrodes. To proof the quality of these contacts, I–V curves, photoresponse and photoconductivity of a single SiNW were measured. Furthermore, the measured photoconductivity in dependence on the wavelength of illuminated light and was compared with calculations predicting the absorption spectra of an individual SiNW.

  4. Applying contact to individual silicon nanowires using a dielectrophoresis (DEP)-based technique

    Energy Technology Data Exchange (ETDEWEB)

    Leiterer, Christian, E-mail: christian.leiterer@gmail.com [Institute of Photonic Technology (Germany); Broenstrup, Gerald [Max-Planck-Institute for the Science of Light (Germany); Jahr, Norbert; Urban, Matthias; Arnold, Cornelia; Christiansen, Silke; Fritzsche, Wolfgang [Institute of Photonic Technology (Germany)

    2013-05-15

    One major challenge for the technological use of nanostructures is the control of their electrical and optoelectronic properties. For that purpose, extensive research into the electrical characterization and therefore a fast and reliable way of contacting these structures are needed. Here, we report on a new, dielectrophoresis (DEP)-based technique, which enables to apply sufficient and reliable contact to individual nanostructures, like semiconducting nanowires (NW), easily and without the need for lithography. The DEP contacting technique presented in this article can be done without high-tech equipment and monitored in situ with an optical microscope. In the presented experiments, individual SiNWs are trapped and subsequently welded between two photolithographically pre-patterned electrodes by applying varying AC voltages to the electrodes. To proof the quality of these contacts, I-V curves, photoresponse and photoconductivity of a single SiNW were measured. Furthermore, the measured photoconductivity in dependence on the wavelength of illuminated light and was compared with calculations predicting the absorption spectra of an individual SiNW.

  5. Silicon nanowires: electron holography studies of doped p–n junctions and biased Schottky barriers

    International Nuclear Information System (INIS)

    We report an in situ examination of individual Si p–n junction nanowires (NWs) using off-axis electron holography (EH) during transmission electron microscopy. The SiNWs were synthesized by chemical vapor deposition with an axial dopant profile from n- to p-type, and then placed inside the transmission electron microscope as a cantilever geometry in contact with a movable Pt probe for in situ biasing measurements during simultaneous EH observations. The phase shift from EH indicates the potential shift between the p- and n-segments to be 1.03 ± 0.17 V due to the built-in voltage. The I–V characteristics of a single SiNW indicate the formation of a Schottky barrier between the NW tip and the movable Pt contact. EH observations show a strong concentration of electric field at this contact, preventing a change in the Si energy bands in the p–n junction region due to the applied bias. (paper)

  6. Polysilicon Nanowires for chemical sensing applications

    OpenAIRE

    Jacques, Emmanuel; Ni, Liang; Salaun, Anne-Claire; Rogel, Régis; Pichon, Laurent

    2012-01-01

    Polycrystalline silicon nanowires are synthesized using a classical fabrication method commonly used in microelectronic industry: the sidewall spacer formation technique. Assets of this technological process rest on low cost lithographic tools use, classical silicon planar technology compatibility and the possibility to get by direct patterning numerous parallel nanowires with precise location on the substrate. Grounded and suspended polycrystalline silicon nanowires with a curvature radius a...

  7. Ultra-high-speed optical serial-to-parallel data conversion by time-domain optical Fourier transformation in a silicon nanowire

    OpenAIRE

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Hu, Hao; Ji, Hua; Lillieholm, Mads; Galili, Michael; Clausen, Anders; Pu, Minhao; Yvind, Kresten; Hvam, Jørn Märcher; Jeppesen, Palle; Oxenløwe, Leif Katsuo

    2011-01-01

    We demonstrate conversion from 64 × 10 Gbit/s optical timedivision multiplexed (OTDM) data to dense wavelength division multiplexed (DWDM) data with 25 GHz spacing. The conversion is achieved by time-domain optical Fourier transformation (OFT) based on four-wave mixing (FWM) in a 3.6 mm long silicon nanowire. A total of 40 out of 64 tributaries of a 64 × 10 Gbit/s OTDM-DPSK data signal are simultaneously converted with a bit-error rate (BER) performance below the 2 × 10−3 FEC limit. Using a 5...

  8. High Area Capacity Lithium-Sulfur Full-cell Battery with Prelitiathed Silicon Nanowire-Carbon Anodes for Long Cycling Stability

    OpenAIRE

    Andreas Krause; Susanne Dörfler; Markus Piwko; Florian M. Wisser; Tony Jaumann; Eike Ahrens; Lars Giebeler; Holger Althues; Stefan Schädlich; Julia Grothe; Andrea Jeffery; Matthias Grube; Jan Brückner; Jan Martin; Jürgen Eckert

    2016-01-01

    We show full Li/S cells with the use of balanced and high capacity electrodes to address high power electro-mobile applications. The anode is made of an assembly comprising of silicon nanowires as active material densely and conformally grown on a 3D carbon mesh as a light-weight current collector, offering extremely high areal capacity for reversible Li storage of up to 9 mAh/cm2. The dense growth is guaranteed by a versatile Au precursor developed for homogenous Au layer deposition on 3D su...

  9. All-optical KarhunenLoeve Transform Using Multimode Interference Structures on Silicon Nanowires

    Science.gov (United States)

    Le, Trung-Thanh

    2011-12-01

    A variety of unitary transforms have attracted considerable attention for their application in data, image compression and other signal processing applications. Among many transforms, the KarhunenLoeve transform (KLT) is known to be optimal because of its advantages of computational efficiency, residual correlation and rate distortion criterion. In this paper, it is shown that the all-optical KarhunenLoeve transform can be realized using multimode interference (MMI) structures on silicon wire waveguides. The transfer matrix method (TMM) and the beam propagation method (BPM) are used to verify and optimally design the proposed devices.

  10. Axial InAs/GaAs heterostructures on silicon in a nanowire geometry

    International Nuclear Information System (INIS)

    InAs segments were grown on top of GaAs islands, initially created by droplet epitaxy on silicon substrate. We systematically explored the growth-parameter space for the deposition of InAs, identifying the conditions for the selective growth on GaAs and for purely axial growth. The axial InAs segments were formed with their sidewalls rotated by 30∘ compared to the GaAs base islands underneath. Synchrotron X-ray diffraction experiments revealed that the InAs segments are grown relaxed on top of GaAs, with a predominantly zincblende crystal structure and stacking faults. (paper)

  11. Stress effects on the initial lithiation of crystalline silicon nanowires: reactive molecular dynamics simulations using ReaxFF.

    Science.gov (United States)

    Ostadhossein, Alireza; Cubuk, Ekin D; Tritsaris, Georgios A; Kaxiras, Efthimios; Zhang, Sulin; van Duin, Adri C T

    2015-02-01

    Silicon (Si) has been recognized as a promising anode material for the next-generation high-capacity lithium (Li)-ion batteries because of its high theoretical energy density. Recent in situ transmission electron microscopy (TEM) revealed that the electrochemical lithiation of crystalline Si nanowires (c-SiNWs) proceeds by the migration of the interface between the lithiated Si (LixSi) shell and the pristine unlithiated core, accompanied by solid-state amorphization. The underlying atomic mechanisms of Li insertion into c-Si remain poorly understood. Herein, we perform molecular dynamics (MD) simulations using the reactive force field (ReaxFF) to characterize the lithiation process of c-SiNWs. Our calculations show that ReaxFF can accurately reproduce the energy barriers of Li migration from DFT calculations in both crystalline (c-Si) and amorphous Si (a-Si). The ReaxFF-based MD simulations reveal that Li insertion into interlayer spacing between two adjacent (111) planes results in the peeling-off of the (111) facets and subsequent amorphization, in agreement with experimental observations. We find that breaking of the Si-Si bonds between (111)-bilayers requires a rather high local Li concentration, which explains the atomically sharp amorphous-crystalline interface (ACI). Our stress analysis shows that lithiation induces compressive stress at the ACI layer, causing retardation or even the stagnation of the reaction front, also in good agreement with TEM observations. Lithiation at high temperatures (e.g. 1200 K) shows that Li insertion into c-SiNW results in an amorphous to crystalline phase transformation at Li : Si composition of ∼4.2 : 1. Our modeling results provide a comprehensive picture of the effects of reaction and diffusion-induced stress on the interfacial dynamics and mechanical degradation of SiNW anodes under chemo-mechanical lithiation. PMID:25559797

  12. Observation of Aharonov-Bohm and Al'tshuler-Aronov-Spivak oscillations in the background of universal conductance fluctuations in silicon nanowires

    Science.gov (United States)

    Mtsuko, Davie; Aslan, Tahir; Ncube, Siphephile; Coleman, Christopher; Wamwangi, Daniel; Bhattacharyya, Somnath

    2016-02-01

    Magnetoresistance (MR) oscillations of multiple periodicities are recorded in singly connected silicon nanowires of diameter ≈50 \\text{nm} . At 100 K we observe oscillations of periodicity ≈1.78 \\text{T} and 0.444 T corresponding to h/e and h/4e Aharonov-Bohm (AB) oscillations, whereas at 10 K we record periodicities of 0.98 T, 0.49 T and 0.25 T corresponding to h/e, h/2e (Al'tshuler-Aronov-Spivak (AAS)) and h/4e oscillations. At 2.5 K we find magnetoresistance oscillations with multiple periodicities of 1.3 T, 0.52 T, and 0.325 T corresponding to AB and AAS oscillations. The h/2e and h/4e peaks can be attributed to the interference of time-reversed paths originating from the core orbits that scatter coherently on the surface of the nanowires multiple times. We also observed 20 mT and 60 mT oscillations of small amplitude superimposed on a quasi-periodic background which we attribute to the quantum interference of special surface states associated with skipping orbits that propagate quasi-ballistically. The aperiodic fluctuations in the MR at all temperatures are universal conductance fluctuations (UCF) originating from randomly spaced impurity scattering in the core of the nanowire.

  13. Facile fabrication of a silicon nanowire sensor by two size reduction steps for detection of alpha-fetoprotein biomarker of liver cancer

    Science.gov (United States)

    Binh Pham, Van; ThanhTung Pham, Xuan; Nhat Khoa Phan, Thanh; Thanh Tuyen Le, Thi; Chien Dang, Mau

    2015-12-01

    We present a facile technique that only uses conventional micro-techniques and two size-reduction steps to fabricate wafer-scale silicon nanowire (SiNW) with widths of 200 nm. Initially, conventional lithography was used to pattern SiNW with 2 μm width. Then the nanowire width was decreased to 200 nm by two size-reduction steps with isotropic wet etching. The fabricated SiNW was further investigated when used with nanowire field-effect sensors. The electrical characteristics of the fabricated SiNW devices were characterized and pH sensitivity was investigated. Then a simple and effective surface modification process was carried out to modify SiNW for subsequent binding of a desired receptor. The complete SiNW-based biosensor was then used to detect alpha-fetoprotein (AFP), one of the medically approved biomarkers for liver cancer diagnosis. Electrical measurements showed that the developed SiNW biosensor could detect AFP with concentrations of about 100 ng mL-1. This concentration is lower than the necessary AFP concentration for liver cancer diagnosis.

  14. Preparation of well-aligned carbon nanotubes/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

    Institute of Scientific and Technical Information of China (English)

    李梦轲; 陆梅; 王成伟; 力虎林

    2002-01-01

    The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler- Nordheim tunneling mechanism and current-voltage (I -V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be utilized to synthesize nanoscale PN junction or Schottky diode device. This process also could be useful for the fabrication of SiNWs and other nanoscale core-sheath composite structure nanowires with chemically inert interfaces for nanoscale electronic and device applications where surface oxidation is undesirable. The diameters and lengths of nanoscale composite structure arrays can be dominated easily, and the experimental result shows that the curling and twisting structures are fewer than those prepared by other synthesized methods.

  15. Hierarchical silicon nanowires-carbon textiles matrix as a binder-free anode for high-performance advanced lithium-ion batteries

    Science.gov (United States)

    Liu, Bin; Wang, Xianfu; Chen, Haitian; Wang, Zhuoran; Chen, Di; Cheng, Yi-Bing; Zhou, Chongwu; Shen, Guozhen

    2013-04-01

    Toward the increasing demands of portable energy storage and electric vehicle applications, the widely used graphite anodes with significant drawbacks become more and more unsuitable. Herein, we report a novel scaffold of hierarchical silicon nanowires-carbon textiles anodes fabricated via a facile method. Further, complete lithium-ion batteries based on Si and commercial LiCoO2 materials were assembled to investigate their corresponding across-the-aboard performances, demonstrating their enhanced specific capacity (2950 mAh g-1 at 0.2 C), good repeatability/rate capability (even >900 mAh g-1 at high rate of 5 C), long cycling life, and excellent stability in various external conditions (curvature, temperature, and humidity). Above results light the way to principally replacing graphite anodes with silicon-based electrodes which was confirmed to have better comprehensive performances.

  16. Optimization of pH sensing using silicon nanowire field effect transistors with HfO2 as the sensing surface

    International Nuclear Information System (INIS)

    Silicon nanowire field effect transistor sensors with SiO2/HfO2 as the gate dielectric sensing surface are fabricated using a top down approach. These sensors are optimized for pH sensing with two key characteristics. First, the pH sensitivity is shown to be independent of buffer concentration. Second, the observed pH sensitivity is enhanced and is equal to the Nernst maximum sensitivity limit of 59 mV/pH with a corresponding subthreshold drain current change of ∼ 650%/pH. These two enhanced pH sensing characteristics are attributed to the use of HfO2 as the sensing surface and an optimized fabrication process compatible with silicon processing technology.

  17. Optimization of pH sensing using silicon nanowire field effect transistors with HfO{sub 2} as the sensing surface

    Energy Technology Data Exchange (ETDEWEB)

    Zafar, Sufi; D' Emic, Christopher; Afzali, Ali; Fletcher, Benjamin; Zhu, Y; Ning, Tak [IBM T J Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States)

    2011-10-07

    Silicon nanowire field effect transistor sensors with SiO{sub 2}/HfO{sub 2} as the gate dielectric sensing surface are fabricated using a top down approach. These sensors are optimized for pH sensing with two key characteristics. First, the pH sensitivity is shown to be independent of buffer concentration. Second, the observed pH sensitivity is enhanced and is equal to the Nernst maximum sensitivity limit of 59 mV/pH with a corresponding subthreshold drain current change of {approx} 650%/pH. These two enhanced pH sensing characteristics are attributed to the use of HfO{sub 2} as the sensing surface and an optimized fabrication process compatible with silicon processing technology.

  18. Direct-to-indirect bandgap transitions in ⟨ 110 ⟩ silicon nanowires

    Science.gov (United States)

    Jensen, I. J. T.; Ulyashin, A. G.; Løvvik, O. M.

    2016-01-01

    The bandstructure of ⟨ 110 ⟩ silicon nano wires (SiNWs) with diameters (d) up to 6.1 nm were studied using density functional theory. Three types of surface termination were investigated: H, F, and OH; all giving quantum confinement induced direct bandgaps in the investigated size range. Comparison of the calculated results to reported experimental values showed that trends in the bandstructure behaviour were well reproduced. By studying the relative decrease of global and local minima in the conduction band minimum with increasing d, it was possible to predict a direct-to-indirect bandgap transition at d = 9.2, 9.5, and 11.4 nm for H, F, and OH terminated NWs, respectively.

  19. Melanin: spin behaviour and implications for bioelectronic devices (Presentation Recording)

    Science.gov (United States)

    Meredith, Paul; Sheliakina, Margarita; Mostert, Bernard

    2015-10-01

    The melanins are a broad class of pigmentary macromolecules found through nature that perform a wide range of functions including photo-protection [1]. The most common melanin - the brown, black pigment eumelanin, has been much studied because of its role in melanoma and also for its functional material properties [2]. Synthetic eumelanin has been shown to be photoconductive in the solid state and also possess a water content dependent dark conductivity [3]. It is now well established that these electrical properties arise from hybrid ionic-electronic behaviour, leading to the proposition that melanins could be model biocompatible systems for ion-to-electron transduction in bioelectronics. In my talk, I will discuss the basic science behind these bioelectronics properties - electrical and optical. In this context I will also describe recent electron paramagnetic spin studies which isolate the role of the various chemical moieties responsible for the hybrid ionic-electronic behaviour. I will also highlight preliminary results on prototype melanin-based bioelectronics devices and discuss possible architectures to realise elements such as solid-state switches and transducers. [1] "The physical and chemical properties of eumelanin", P. Meredith and T. Sarna, Pigment Cell Research, 19(6), pp572-594 (2006). [2] "Electronic and optoelectronic materials and devices inspired by nature", P Meredith, C.J. Bettinger, M. Irimia-Vladu, A.B. Mostert and P.E. Schwenn, Reports on Progress in Physics, 76, 034501 (2013). [3] "Is melanin a semiconductor: humidity induced self doping and the electrical conductivity of a biopolymer", A.B. Mostert, B.J. Powell, F.L. Pratt, G.R. Hanson, T. Sarna, I.R. Gentle and P. Meredith, Proceedings of the National Academy of Sciences of the USA, 109(23), 8943-8947 (2012).

  20. Study the Characteristic of P-Type Junction-Less Side Gate Silicon Nanowire Transistor Fabricated by Atomic Force Microscopy Lithography

    Directory of Open Access Journals (Sweden)

    Arash Dehzangi

    2011-01-01

    Full Text Available Problem statement: Nanotransistor now is one of the most promising fields in nanoelectronics in order to decrease the energy consuming and application to create developed programmable information processors. Most of Computing and communications companies invest hundreds of millions of dollars in research funds every year to develop smaller transistors. Approach: The Junction-less side gate silicon Nano-wire transistor has been fabricated by Atomic Force Microscopy (AFM and wet etching on p-type Silicon On Insulator (SOI wafer. Then, we checked the characteristic and conductance trend in this device regarding to semi-classical approach by Semiconductor Probe Analyser (SPA. Results: We observed in characteristic of the device directly proportionality of the negative gate voltage and Source-Drain current. In semi classical approach, negative Gate voltage decreased the energy States of the Nano-wire between the source and the drain. The graph for positive gate voltage plotted as well to check. In other hand, the conductance will be following characteristic due to varying the gate voltage under the different drain-source voltage. Conclusion: The channel energy states are supposed to locate between two electrochemical potentials of the contacts in order to transform the charge. For the p-type channel the transform of the carriers is located in valence band and changing the positive or negative gate voltage, making the valence band energy states out of or in the area between the electrochemical potentials of the contacts causing the current reduced or increased.

  1. 硅纳米线阵列的制备及其光电应用%Preparation and Optoelectronic Applications of Silicon Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    刘莉; 曹阳; 贺军辉; 杨巧文

    2013-01-01

    Recent years, silicon nanowire arrays have aroused extensive attention among scientists and engineers due to their unique characteristics such as excellent antireflection in both wide wavelength range and wide incidence angle and their great potentials in the field of optoelectronics. This paper reviews the latest research progress in preparation of silicon nanowire arrays and their optoelectronic applications. The preparation methods that have been verified are classified mainly into two categories, i. e. , " bottom-up " and" top-down", including template-assisted chemical vapor deposition, chemical vapor deposition combined with Langmuir-Blodgett technology and metal-catalyzed chemical etching. The third method is at the present time the most frequently used as well as the simplest one, and is discussed in detail in respect of the etching steps, mechanism and controlling parameters. As for the optoelectronic applications of silicon nanowire arrays, this review mainly describes those in photodetectors, conventional solar cells, photoelectrochemical solar cells, photocatalytic water splitting, and photocatalytic degradation of organic pollutants. Finally, an outlook is made about how to improve the photoelectrical conversion efficiency and avoid the corrosion of silicon nanowire arrays, which indicates that surface modification and resulting properties may be a future research direction for silicon nanowire arrays research.%近年来,硅纳米线阵列在宽波段、宽入射角范围内优异的减反射性能及其在光电领域的巨大应用前景引起了相关研究者的广泛关注.本文综述了国内外硅纳米线阵列的制备及其在光电应用方面的最新研究进展.关于硅纳米线阵列的制备方法,主要从“自下而上”和“自上而下”两大类出发,分别阐述了模板辅助的化学气相沉积法、化学气相沉积结合Langmuir-Blodgett技术法和金属催化化学刻蚀法,其中重点介绍了目前使用最为

  2. Controlled growth of single nanowires within a supported alumina template

    Energy Technology Data Exchange (ETDEWEB)

    Vlad, A [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Matefi-Tempfli, M [Unite de Physico-Chimie et de Physique des Materiaux, UCL, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve (Belgium); Faniel, S [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Bayot, V [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Melinte, S [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Piraux, L [Unite de Physico-Chimie et de Physique des Materiaux, UCL, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve (Belgium); Matefi-Tempfli, S [Unite de Physico-Chimie et de Physique des Materiaux, UCL, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve (Belgium)

    2006-10-14

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire patterns as well as arrays of single nanowires with a precise position and spacing.

  3. Controlled growth of single nanowires within a supported alumina template

    Science.gov (United States)

    Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.; Bayot, V.; Melinte, S.; Piraux, L.; Mátéfi-Tempfli, S.

    2006-10-01

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire patterns as well as arrays of single nanowires with a precise position and spacing.

  4. Multilevel electrochemical signal detections of metalloprotein heterolayers for bioelectronic device

    International Nuclear Information System (INIS)

    In the present study, we investigated the simultaneous detection of multilevel electrochemical signals from various metalloprotein heterolayers for the bioelectronic devices. A layer-by-layer assembly method based on simple electrostatic interaction was introduced to form protein bilayers. The gold substrate was modified with poly (ethylene glycol) thiol acid as the precursor, which introduced negative charges to the surface. Based on the isoelectric point, net-charge controlled metalloproteins by pH adjustment were sequentially immobilized on this negatively charged substrate. The degree of protein immobilization on the gold substrate was confirmed by surface plasmon resonance spectroscopy, and the surface topology changes due to the protein immobilization were confirmed by atomic force microscopy. Redox signals in the protein layers were measured by cyclic voltammetry. As a result, various redox signals generated from different metalloproteins on a single electrode were monitored. This proposed method for the detection of multi-level electrochemical signals can be directly applied to bioelectronic devices that store multi-information in a single electrode. - Highlights: • We fabricated heterolayers composed of various metalloproteins. • Metalloproteins were immobilized by layer-by-layer assembly. • The degree of immobilization was controlled by the net charge of metalloproteins. • Various redox signals generated from heterolayers were well monitored

  5. Inquisition of Microcystis aeruginosa and Synechocystis nanowires: characterization and modelling.

    Science.gov (United States)

    Sure, Sandeep; Torriero, Angel A J; Gaur, Aditya; Li, Lu Hua; Chen, Ying; Tripathi, Chandrakant; Adholeya, Alok; Ackland, M Leigh; Kochar, Mandira

    2015-11-01

    Identification of extracellular conductive pilus-like structures (PLS) i.e. microbial nanowires has spurred great interest among scientists due to their potential applications in the fields of biogeochemistry, bioelectronics, bioremediation etc. Using conductive atomic force microscopy, we identified microbial nanowires in Microcystis aeruginosa PCC 7806 which is an aerobic, photosynthetic microorganism. We also confirmed the earlier finding that Synechocystis sp. PCC 6803 produces microbial nanowires. In contrast to the use of highly instrumented continuous flow reactors for Synechocystis reported earlier, we identified simple and optimum culture conditions which allow increased production of nanowires in both test cyanobacteria. Production of these nanowires in Synechocystis and Microcystis were found to be sensitive to the availability of carbon source and light intensity. These structures seem to be proteinaceous in nature and their diameter was found to be 4.5-7 and 8.5-11 nm in Synechocystis and M. aeruginosa, respectively. Characterization of Synechocystis nanowires by transmission electron microscopy and biochemical techniques confirmed that they are type IV pili (TFP) while nanowires in M. aeruginosa were found to be similar to an unnamed protein (GenBank : CAO90693.1). Modelling studies of the Synechocystis TFP subunit i.e. PilA1 indicated that strategically placed aromatic amino acids may be involved in electron transfer through these nanowires. This study identifies PLS from Microcystis which can act as nanowires and supports the earlier hypothesis that microbial nanowires are widespread in nature and play diverse roles. PMID:26319534

  6. Stacking faults in SiC nanowires.

    Science.gov (United States)

    Wallis, K L; Wieligor, M; Zerda, T W; Stelmakh, S; Gierlotka, S; Palosz, B

    2008-07-01

    SiC nanowires were obtained by a reaction between vapor silicon and multiwall carbon nanotubes, CNT, in vacuum at 1200 degrees C. Raman and IR spectrometry, X-ray diffraction and high resolution transmission electron microscopy, HRTEM, were used to characterize properties of SiC nanowires. Morphology and chemical composition of the nanowires was similar for all samples, but concentration of structural defects varied and depended on the origin of CNT. Stacking faults were characterized by HRTEM and Raman spectroscopy, and both techniques provided complementary results. Raman microscopy allowed studying structural defects inside individual nanowires. A thin layer of amorphous silicon carbide was detected on the surface of nanowires. PMID:19051903

  7. Optical properties of nanowire metamaterials with gain

    DEFF Research Database (Denmark)

    Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi;

    2016-01-01

    The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

  8. Surface Emitting, High Efficiency Near-Vacuum Ultraviolet Light Source with Aluminum Nitride Nanowires Monolithically Grown on Silicon.

    Science.gov (United States)

    Zhao, S; Djavid, M; Mi, Z

    2015-10-14

    To date, it has remained challenging to realize electrically injected light sources in the vacuum ultraviolet wavelength range (∼200 nm or shorter), which are important for a broad range of applications, including sensing, surface treatment, and photochemical analysis. In this Letter, we have demonstrated such a light source with molecular beam epitaxially grown aluminum nitride (AlN) nanowires on low cost, large area Si substrate. Detailed angle dependent electroluminescence studies suggest that, albeit the light is TM polarized, the dominant light emission direction is from the nanowire top surface, that is, along the c axis, due to the strong light scattering effect. Such an efficient surface emitting device was not previously possible using conventional c-plane AlN planar structures. The AlN nanowire LEDs exhibit an extremely large electrical efficiency (>85%), which is nearly ten times higher than the previously reported AlN planar devices. Our detailed studies further suggest that the performance of AlN nanowire LEDs is predominantly limited by electron overflow. This study provides important insight on the fundamental emission characteristics of AlN nanowire LEDs and also offers a viable path to realize an efficient surface emitting near-vacuum ultraviolet light source through direct electrical injection. PMID:26375576

  9. Advances in the Application of Silicon and Germanium Nanowires for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Kennedy, Tadhg; Brandon, Michael; Ryan, Kevin M

    2016-07-01

    Li-alloying materials such as Si and Ge nanowires have emerged as the forerunners to replace the current, relatively low-capacity carbonaceous based Li-ion anodes. Since the initial report of binder-free nanowire electrodes, a vast body of research has been carried out in which the performance and cycle life has significantly progressed. The study of such electrodes has provided invaluable insights into the cycling behavior of Si and Ge, as the effects of repeated lithiation/delithiation on the material can be observed without interference from conductive additives or binders. Here, some of the key developments in this area are looked at, focusing on the problems encountered by Li-alloying electrodes in general (e.g., pulverization, loss of contact with current collector etc.) and how the study of nanowire electrodes has overcome these issues. Some key nanowire studies that have elucidated the consequences of the alloying/dealloying process on the morphology of Si and Ge are also considered, in particular looking at the impact that effects such as pore formation and lithium-assisted welding have on performance. Finally, the challenges for the practical implementation of nanowire anodes within the context of the current understanding of such systems are discussed. PMID:26855084

  10. Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method

    KAUST Repository

    Najar, Adel

    2012-01-01

    We report on the structural and optical properties of porous silicon nanowires (PSiNWs) fabricated using silver (Ag) ions assisted electroless etching method. Silicon nanocrystallites with sizes <5 nm embedded in amorphous silica have been observed from PSiNW samples etched using the optimum hydrofluoric acid (HF) concentration. The strongest photoluminescence (PL) signal has been measured from samples etched with 4.8 M of HF, beyond which a significant decreasing in PL emission intensity has been observed. A qualitative model is proposed for the formation of PSiNWs in the presence of Ag catalyst. This model affirms our observations in PL enhancement for samples etched using HF <4.8 M and the eventual PL reduction for samples etched beyond 4.8 M of HF concentration. The enhancement in PL signals has been associated to the formation of PSiNWs and the quantum confinement effect in the Si nanocrystallites. Compared to PSiNWs without Si-O x, the HF treated samples exhibited significant blue PL peak shift of 100 nm. This effect has been correlated to the formation of defect states in the surface oxide. PSiNWs fabricated using the electroless etching method can find useful applications in optical sensors and as anti-reflection layer in silicon-based solar cells. © 2012 American Institute of Physics.

  11. III-nitride disk-in-nanowire 1.2 μm monolithic diode laser on (001)silicon

    International Nuclear Information System (INIS)

    III-nitride nanowire diode heterostructures with multiple In0.85Ga0.15N disks and graded InGaN mode confining regions were grown by molecular beam epitaxy on (001)Si substrates. The aerial density of the 60 nm nanowires is ∼3 × 1010 cm−2. A radiative recombination lifetime of 1.84 ns in the disks is measured by time-resolved luminescence measurements. Edge-emitting nanowire lasers have been fabricated and characterized. Measured values of Jth, T0, and dg/dn in these devices are 1.24 kA/cm2, 242 K, and 5.6 × 10−17 cm2, respectively. The peak emission is observed at ∼1.2 μm

  12. Electrochemical Fabrication of Functional Gelatin-Based Bioelectronic Interface.

    Science.gov (United States)

    Peng, Xianghong; Liu, Yi; Bentley, William E; Payne, Gregory F

    2016-02-01

    Gelatin remains one of the most important biopolymeric material platforms because of its availability, safety, biocompatibility, biodegradability, and stimuli-responsive properties. Here we report a simple, rapid, and reagentless anodic deposition method to assemble gelatin hydrogels from aqueous salt solutions onto an electrode surface. Results indicate that anodic reactions partially oxidize gelatin to yield a covalently cross-linked network that can perform multiple functions. First, anodically deposited gelatin remains activated, allowing covalent protein grafting and thus enabling biofunctionalization for electrochemical biosensing. Second, the anodically deposited gelatin retains its thermally responsive physical cross-linking properties that enable switching functions. Finally, the physical and chemical cross-linking mechanisms are reversible, which enables self-healing functions. Thus, anodic deposition provides a facile method to assemble gelatin-based multifunctional matrices for diverse applications in bioelectronics. PMID:26752426

  13. Fabrication and characterization of silicon nanowire p-i-n MOS gated diode for use as p-type tunnel FET

    Science.gov (United States)

    Brouzet, V.; Salem, B.; Periwal, P.; Rosaz, G.; Baron, T.; Bassani, F.; Gentile, P.; Ghibaudo, G.

    2015-11-01

    In this paper, we present the fabrication and electrical characterization of a MOS gated diode based on axially doped silicon nanowire (NW) p-i-n junctions. These nanowires are grown by chemical vapour deposition (CVD) using the vapour-liquid-solid (VLS) mechanism. NWs have a length of about 7 \\upmu {m} with 3 \\upmu {m} of doped regions (p-type and n-type) and 1 \\upmu {m} of intrinsic region. The gate stack is composed of 15 nm of hafnium dioxide ({HfO}2), 80 nm of nickel and 120 nm of aluminium. At room temperature, I_{{on}} =-52 {nA}/\\upmu {m} (V_{{DS}}=-0.5 {V}, V_{{GS}}=-4 {V}), and an I_{{on}}/I_{{off}} ratio of about 104 with a very low I_{{off}} current has been obtained. Electrical measurements are carried out between 90 and 390 K, and we show that the I on current is less temperature dependent below 250 K. We also observe that the ON current is increasing between 250 and 390 K. These transfer characteristics at low and high temperature confirm the tunnelling transport mechanisms in our devices.

  14. Preparation of well-aligned carbon nanotubes/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

    Institute of Scientific and Technical Information of China (English)

    李梦轲; 力虎林; 陆梅; 王成伟

    2002-01-01

    The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler-Nordheim tunneling mechanism and current-voltage (/-V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be

  15. Carbon Nanotube-Silicon Nanowire Heterojunction Solar Cells with Gas-Dependent Photovoltaic Performances and Their Application in Self-Powered NO2 Detecting

    Science.gov (United States)

    Jia, Yi; Zhang, Zexia; Xiao, Lin; Lv, Ruitao

    2016-06-01

    A multifunctional device combining photovoltaic conversion and toxic gas sensitivity is reported. In this device, carbon nanotube (CNT) membranes are used to cover onto silicon nanowire (SiNW) arrays to form heterojunction. The porous structure and large specific surface area in the heterojunction structure are both benefits for gas adsorption. In virtue of these merits, gas doping is a feasible method to improve cell's performance and the device can also work as a self-powered gas sensor beyond a solar cell. It shows a significant improvement in cell efficiency (more than 200 times) after NO2 molecules doping (device working as a solar cell) and a fast, reversible response property for NO2 detection (device working as a gas sensor). Such multifunctional CNT-SiNW structure can be expected to open a new avenue for developing self-powered, efficient toxic gas-sensing devices in the future.

  16. Carbon Nanotube-Silicon Nanowire Heterojunction Solar Cells with Gas-Dependent Photovoltaic Performances and Their Application in Self-Powered NO2 Detecting.

    Science.gov (United States)

    Jia, Yi; Zhang, Zexia; Xiao, Lin; Lv, Ruitao

    2016-12-01

    A multifunctional device combining photovoltaic conversion and toxic gas sensitivity is reported. In this device, carbon nanotube (CNT) membranes are used to cover onto silicon nanowire (SiNW) arrays to form heterojunction. The porous structure and large specific surface area in the heterojunction structure are both benefits for gas adsorption. In virtue of these merits, gas doping is a feasible method to improve cell's performance and the device can also work as a self-powered gas sensor beyond a solar cell. It shows a significant improvement in cell efficiency (more than 200 times) after NO2 molecules doping (device working as a solar cell) and a fast, reversible response property for NO2 detection (device working as a gas sensor). Such multifunctional CNT-SiNW structure can be expected to open a new avenue for developing self-powered, efficient toxic gas-sensing devices in the future. PMID:27299654

  17. Multiplex electrical detection of avian influenza and human immunodeficiency virus with an underlap-embedded silicon nanowire field-effect transistor.

    Science.gov (United States)

    Kim, Jee-Yeon; Ahn, Jae-Hyuk; Moon, Dong-Il; Park, Tae Jung; Lee, Sang Yup; Choi, Yang-Kyu

    2014-05-15

    The label-free electrical detection of the binding of antibodies and antigens of avian influenza (AI) and human immunodeficiency (HIV) viruses is demonstrated through an underlap-embedded silicon (Si) nanowire field-effect transistor. The proposed sensor was fabricated on a silicon bulk wafer by a top-down process. Specifically, a Si nanowire was fabricated by a combined isotropic and anisotropic patterning technique, which is one route plasma etching process. The sensor was fabricated by a self-aligned process to the gate with tilted implantation, and it allows precise control of the underlap region. This was problematic in earlier underlap field-effect transistors fabricated by a conventional gate-last process. As a sensing metric to detect the binding of a targeted antibody, the transfer characteristic change was traced. Before and after differences between the antibody binding results were caused by changes in the channel potential on the underlap region due to the charge effect arising from the biomolecules; this is also supported by a simulation. Furthermore, the multiplex detection of AI and HIV is demonstrated, showing distinctive selectivity in each case. Thus, the proposed device has inherent benefits for the label-free, electrical, and multiplex detection of biomolecules. Moreover, its processes are compatible with commercialized technology presently used to fabricate semiconductor devices. This advantage is attractive for those involved in the construction of a point-of-care testing (POCT) system on a chip involving simple, low-cost and low-risk fabrication processes of novel structures and materials. PMID:24374298

  18. Facile Five-Step Heteroepitaxial Growth of GaAs Nanowires on Silicon Substrates and the Twin Formation Mechanism.

    Science.gov (United States)

    Yao, Maoqing; Sheng, Chunyang; Ge, Mingyuan; Chi, Chun-Yung; Cong, Sen; Nakano, Aiichiro; Dapkus, P Daniel; Zhou, Chongwu

    2016-02-23

    Monolithic integration of III-V semiconductors with Si has been pursued for some time in the semiconductor industry. However, the mismatch of lattice constants and thermal expansion coefficients represents a large technological challenge for the heteroepitaxial growth. Nanowires, due to their small lateral dimension, can relieve strain and mitigate dislocation formation to allow single-crystal III-V materials to be grown on Si. Here, we report a facile five-step heteroepitaxial growth of GaAs nanowires on Si using selective area growth (SAG) in metalorganic chemical vapor deposition, and we further report an in-depth study on the twin formation mechanism. Rotational twin defects were observed in the nanowire structures and showed strong dependence on the growth condition and nanowire size. We adopt a model of faceted growth to demonstrate the formation of twins during growth, which is well supported by both a transmission electron microscopy study and simulation based on nucleation energetics. Our study has led to twin-free segments in the length up to 80 nm, a significant improvement compared to previous work using SAG. The achievements may open up opportunities for future functional III-V-on-Si heterostructure devices. PMID:26831573

  19. Photoelectrochemistry of Semiconductor Nanowire Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mallouk, Thomas E; Redwing, Joan M

    2009-11-10

    This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.

  20. The use of the grey-Taguchi method for the optimization of a silicon nanowires array synthesized using electroless Ag-assisted etching

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, Ai-Huei [National Chiao Tung University, Department of Mechanical Engineering (China); Wu, Wen-Fa [National Nano Device Laboratories (China); Chen, Ding-Yeng, E-mail: dnc@cc.hwh.edu.tw [Hwa Hsia Institute of Technology, Department of Mechanical Engineering (China); Hsu, Chun-Yao, E-mail: cyhsu@mail.lhu.edu.tw [Lunghwa University of Science and Technology, Department of Mechanical Engineering (China)

    2013-09-15

    A simple and convenient method for the production of silicon nanowires (SiNWs) that are single crystalline, well aligned and which have large area is direct synthesis onto p-type (100) silicon (Si) wafers, using electroless Ag-assisted etching, in which Ag is both the oxidant and the catalyst. This study proposes a method for the optimization of the etching process parameters for SiNW arrays with multiple performance characteristics, using grey-Taguchi analysis. The effect of the etching process parameters (etching time, solution (AgNO{sub 3}/HF) temperature, silver nitrate (AgNO{sub 3}) concentration and hydrogen fluoride (HF) concentration) on the length, diameter, structure, and morphology of the SiNW arrays were studied. In the confirmation runs, grey relational analysis shows that the length of the SiNW arrays is increased from 15.80 to 23.07 {mu}m, and the diameter is decreased from 76.77 to 66.65 nm. Further, the linear relationship for the SiNW arrays can be adjusted by increasing the etching time (from 15 to 45 min) and the solution temperature (from 25 to 75 Degree-Sign C). The axial orientation of the SiNWs is determined to be along the [001] direction, which is the same as that of the initial Si wafer. The large area SiNW arrays have potential applications in interconnect, bio-technology and optoelectronic devices.