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Sample records for sb-doped zno nanowires

  1. Effect of Sb-doping on the morphology and dielectric properties of chrysanthemum-like ZnO nanowire clusters

    Science.gov (United States)

    Yan, Jun-Feng; You, Tian-Gui; Zhang, Zhi-Yong; Tian, Jiang-Xiao; Yun, Jiang-Ni; Zhao, Wu

    2012-09-01

    Chrysanthemum-like ZnO nanowire clusters with different Sb-doping concentrations were prepared using a hydrothermal process. The microstructures, morphologies, and dielectric properties of the as-prepared products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission environment scanning electron microscope (FEESEM), and microwave vector network analyzer respectively. The results indicate that the as-prepared products are Sb-doped ZnO single crystallines with a hexagonal wurtzite structure, the flower bud saturation degree Fd is obviously different from that of the pure ZnO nanowire clusters, the good dielectric loss property is found in Sb-doped ZnO products with low density, and the dielectric loss tangent tanδe increases with the increase of the Sb-doping concentration in a certain concentration range.

  2. Synthesis and characterization of Sb doped ZnO thin films for photodetector application

    Science.gov (United States)

    Mohite, S. V.; Rajpure, K. Y.

    2014-02-01

    We report properties of metal-semiconductor-metal (MSM) photoconductive UV detectors based on Sb-doped ZnO thin films. Highly c-axis oriented Sb-doped ZnO thin films were prepared by spray pyrolysis technique onto glass substrates. Optical properties and photocurrent measurements were carried out to study optoelectronic properties of Sb-doped ZnO thin films. These films are highly transparent in visible region and exhibit a steep absorption edge at 365 nm. The electrical resistivity measurement showed semiconducting behaviors of Sb-doped ZnO thin films. All Sb-doped ZnO thin films exhibit n-type electrical conductivity. I-V characteristics of photodetector devices were analyzed by applying 5 V bias. The 3% Sb doped ZnO photodetector shows higher responsivity of 5.1 A/W at 365 nm under 10 μW/cm2 photo-illumination. In order to check the maximal (for the rise) or minimal (for the fall) level of photocurrent, the results on photodetector for 30 s ON and OFF cycles of illumination have been reported.

  3. Preparation of Sb-doped ZnO nanostructures and studies on some of their properties

    Science.gov (United States)

    Ilican, Saliha; Caglar, Yasemin; Caglar, Mujdat; Yakuphanoglu, Fahrettin; Cui, Jingbiao

    2008-10-01

    Sb-doped ZnO nanostructures have been deposited onto glass substrates by a sol-gel method. The structural, optical and electrical properties of the Sb-doped ZnO films were characterized by various techniques including scanning electron microscopy, X-ray diffraction, UV-vis absorption, photoluminescence , and electrical transport measurements. The surface morphology of the nanostructure films is found to depend on the concentration of Sb in the source materials. Band-edge emission at 376 nm and a broad defect band around 530 nm were shown in the photoluminescence spectra. An emission band at 400 nm was also observed, which is likely associated with the interstitial Zn in ZnO. The current-voltage characteristics of the films indicate a non-linear behavior. The conductivity type of the films changes from n-type to p-type with increasing Sb-dopant.

  4. Preparation, characterization of Sb-doped ZnO nanocrystals and their excellent solar light driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Nasser, Ramzi; Othmen, Walid Ben Haj [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University of Tunis El Manar 2092 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University of Tunis El Manar 2092 (Tunisia); Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia)

    2017-01-30

    Highlights: • Sb-ZnO was obtained by modified sol-gel method using citric acid as stabilizing agent. • Sb incorporated both in lattice and interstitial sites. • The formation of (Sb{sub Zn}–2 V{sub Zn}) acceptor level was revealed by photoluminescence studies. • Optimum Sb content to show higher photocatalytic activity was found to be 3%. - Abstract: In the present study, undoped and antimony (Sb) doped ZnO nanocrystals (NCs) were prepared by a simple and economical sol-gel method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the purity of the obtained phase and its high crystallinity. Raman analysis confirms the hexagonal Wurtzite ZnO structure. According to the diffuse reflectance results, the band gap was found to decrease up to 3% of Sb doping (ZSb3 sample). The results of X-ray photoelectron spectroscopy (XPS) measurements reveal that Sb ions occupied both Zn and interstitials sites. The successful substitution of antimony in ZnO lattice suggests the formation of the complex (Sb{sub Zn}–2 V{sub Zn}) acceptor level above the valence band. Particularly for ZSb3 sample, the UV photoluminescence (PL) band presents an obvious red-shift attributed to the formation of this complex. Rhodamine B (RhB) was used to evaluate the photocatalytic activity of Sb-doped ZnO NCs under sunlight irradiation. It was found that oxygen vacancies play a major role in the photocatalytic process by trapping the excited electrons and inhibiting the radiative recombination. During the photocatalytic mechanism, the Sb doping, expressed through the apparition of the (Sb{sub Zn}–2 V{sub Zn}) correspondent acceptor level, enhances the sunlight absorption within the ZnO band gap, which stimulates the generation of hydroxyl radicals and promotes the photocatalytics reaction rates. Such important contribution of the hydroxyl radicals was confirmed experimentally when using ethanol as scavenger in the photocatalytic reaction. The photodegradation

  5. Electrically pumped waveguide lasing from ZnO nanowires.

    Science.gov (United States)

    Chu, Sheng; Wang, Guoping; Zhou, Weihang; Lin, Yuqing; Chernyak, Leonid; Zhao, Jianze; Kong, Jieying; Li, Lin; Ren, Jingjian; Liu, Jianlin

    2011-07-03

    Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide (ZnO), which has a wide direct bandgap and a large exciton binding energy. ZnO-based random lasing has been demonstrated with both optical and electrical pumping, but random lasers suffer from reduced output powers, unstable emission spectra and beam divergence. Here, we demonstrate electrically pumped Fabry-Perot type waveguide lasing from laser diodes that consist of Sb-doped p-type ZnO nanowires and n-type ZnO thin films. The diodes exhibit highly stable lasing at room temperature, and can be modelled with finite-difference time-domain methods.

  6. Electronic properties of a grain boundary in Sb-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, J.M.; Hellsing, B. [Experimental Physics, Chalmers and Goeteborg University, Gothenburg (Sweden); Domingos, H.S.; Bristowe, P.D. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom)]. E-mail: pdb1000@cus.cam.ac.uk

    2001-11-05

    The electronic properties of a {sigma}=13 32.2 deg. [0001] tilt grain boundary in ZnO have been investigated using first-principles calculations. Two atomic models for the boundary have been considered, one of which contains structural units that are consistent with those observed for this orientation using electron microscopy. Doping both the grain boundary models with antimony reveals a strong driving force for segregation. Analysis of the electronic densities of states, bond populations and Mulliken charges shows that antimony creates a localized impurity state in the grain boundary and acts as a donor dopant. The resulting charge accumulation at the grain boundary together with the presence of local bonds that are metallic in character, will influence the mechanism for charge transport across the interface and this is discussed in relation to varistor applications. (author)

  7. Electronic properties of a grain boundary in Sb-doped ZnO

    Science.gov (United States)

    Carlsson, J. M.; Hellsing, B.; Domingos, H. S.; Bristowe, P. D.

    2001-11-01

    The electronic properties of a Σ = 13 32.2° [0001] tilt grain boundary in ZnO have been investigated using first-principles calculations. Two atomic models for the boundary have been considered, one of which contains structural units that are consistent with those observed for this orientation using electron microscopy. Doping both the grain boundary models with antimony reveals a strong driving force for segregation. Analysis of the electronic densities of states, bond populations and Mulliken charges shows that antimony creates a localized impurity state in the grain boundary and acts as a donor dopant. The resulting charge accumulation at the grain boundary together with the presence of local bonds that are metallic in character, will influence the mechanism for charge transport across the interface and this is discussed in relation to varistor applications.

  8. Low-Temperature Facile Synthesis of Sb-Doped p-Type ZnO Nanodisks and Its Application in Homojunction Light-Emitting Diode.

    Science.gov (United States)

    Baek, Sung-Doo; Biswas, Pranab; Kim, Jong-Woo; Kim, Yun Cheol; Lee, Tae Il; Myoung, Jae-Min

    2016-05-25

    This study explores low-temperature solution-process-based seed-layer-free ZnO p-n homojunction light-emitting diode (LED). In order to obtain p-type ZnO nanodisks (NDs), antimony (Sb) was doped into ZnO by using a facile chemical route at 120 °C. The X-ray photoelectron spectra indicated the presence of (SbZn-2VZn) acceptor complex in the Sb-doped ZnO NDs. Using these NDs as freestanding templates, undoped n-type ZnO nanorods (NRs) were epitaxially grown at 95 °C to form ZnO p-n homojunction. The homojunction with a turn-on voltage of 2.5 V was found to be significantly stable up to 100 s under a constant voltage stress of 5 V. A strong orange-red emission was observed by the naked eye under a forward bias of 5 V. The electroluminescence spectra revealed three major peaks at 400, 612, and 742 nm which were attributed to the transitions from Zni to VBM, from Zni to Oi, and from VO to VBM, respectively. The presence of these deep-level defects was confirmed by the photoluminescence of ZnO NRs. This study paves the way for future applications of ZnO homojunction LEDs using low-temperature and low-cost solution processes with the controlled use of native defects.

  9. Electrowetting on ZnO nanowires

    Science.gov (United States)

    Wu, Jun; Xia, Jun; Lei, Wei; Wang, Bao-Ping

    2010-06-01

    In this paper, we study the electrowetting character on ZnO nanowires. We grow the ZnO nanowires on indium tin oxide (ITO) by a hydrothermal method, and the ZnO nanowires surface is further hydrophobized by spin-coating Teflon. Such a prepared surface shows superhydrophobic properties with an initial contact angle 165°. When the applied external voltage between the ITO and the sessile droplet is less than 50 V, the contact angle continuously changed from 165° to 120°, and exhibits instant reversibility. For a slightly higher voltage, a mutation of the contact angle changing to 100° was observed and the contact angle was not reversible after removing the applied voltage, which indicates a transition from non-wetting state to wetting state. Further increasing of the applied voltage, the apparent contact angle decreased to an invariable value 70°, and electrical breakdown emerged synchronously.

  10. Adsorption property of volatile molecules on ZnO nanowires ...

    Indian Academy of Sciences (India)

    7

    energy of the ZnO nanowire and adsorbed ZnO nanowire system, an increase in the total energy was observed after ... This means that conductivity increased when the film surface was exposed to the reducing molecules. .... reality, there will be plenty of vapor molecules which will interact over the entire sensing element ...

  11. Permanent bending and alignment of ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Borschel, Christian; Spindler, Susann; Oertel, Michael; Ronning, Carsten [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Lerose, Damiana [MPI fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle/Saale (Germany); Institut fuer Photonische Technologien, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Bochmann, Arne [Institut fuer Photonische Technologien, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Christiansen, Silke H. [Institut fuer Photonische Technologien, Albert-Einstein-Strasse 9, 07745 Jena (Germany); MPI fuer die Physik des Lichts, Guenther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Nietzsche, Sandor [Zentrum fuer Elektronenmikroskopie, Friedrich-Schiller-Universitaet Jena, Ziegelmuehlenweg 1, 07743 Jena (Germany)

    2011-07-01

    Ion beams can be used to bend or re-align nanowires permanently, after they have been grown. We have irradiated ZnO nanowires with ions of different species and energy, achieving bending and alignment in various directions. We study the bending of single nanowires as well as the simultaneous alignment of large ensembles of ZnO nanowires in detail. Computer simulations show that the bending is initiated by ion beam induced damage. Dislocations are identified to relax stresses and make the bending and alignment permanent and resistant against annealing procedures.

  12. ZnO Nanowire Application in Chemoresistive Sensing: A Review

    Directory of Open Access Journals (Sweden)

    Simas Rackauskas

    2017-11-01

    Full Text Available This article provides an overview of the recent development of ZnO nanowires (NWs for chemoresistive sensing. Working mechanisms of chemoresistive sensors are unified for gas, ultraviolet (UV and bio sensor types: single nanowire and nanowire junction sensors are described, giving the overview for a simple sensor manufacture by multiple nanowire junctions. ZnO NW surface functionalization is discussed, and how this effects the sensing is explained. Further, novel approaches for sensing, using ZnO NW functionalization with other materials such as metal nanoparticles or heterojunctions, are explained, and limiting factors and possible improvements are discussed. The review concludes with the insights and recommendations for the future improvement of the ZnO NW chemoresistive sensing.

  13. Cytotoxicity of ZnO Nanowire Arrays on Excitable Cells

    Directory of Open Access Journals (Sweden)

    Yongchen Wang

    2017-04-01

    Full Text Available Zinc oxide (ZnO nanowires have been widely studied for their applications in electronics, optics, and catalysts. Their semiconducting, piezoelectric, fluorescent, and antibacterial properties have also attracted broad interest in their biomedical applications. Thus, it is imperative to evaluate the biosafety of ZnO nanowires and their biological effects. In this study, the cellular level biological effects of ZnO nanowire arrays are specifically tested on three types of excitable cells, including NG108-15 neuronal cell line, HL-1 cardiac muscle cell line, and neonatal rat cardiomyocytes. Vertically aligned and densely packed ZnO nanowire arrays are synthesized using a solution-based method and used as a substrate for cell culture. The metabolism levels of all three types of cells cultured on ZnO nanowire arrays are studied using the 3-(4,5-dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide (MTT assays of a full factorial design. Under the studied settings, the results show statistically significant inhibitory effects of ZnO nanowire arrays on the metabolism of NG108-15 and HL-1 cells in comparison to gold, glass, and polystyrene substrates, and on the metabolism of cardiomyocytes in comparison to gold substrate.

  14. Adsorption property of volatile molecules on ZnO nanowires ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... Abstract. ZnO nanowires (NWs) were deposited on a glass substrate by the successive ionic layer adsorption and reaction method (SILAR). Sensing response of ZnO NWs towards reducing vapours was tested at ambient temperature (∼32◦. C) by the chemiresistor method. The vapour response was found ...

  15. ZnO Nanowire Array-Based Optoelectronic Devices

    OpenAIRE

    Wang, Guoping

    2011-01-01

    ZnO nanowire array-based optoelectronic devices are discussed in this dissertation. ZnO has a wide band gap of 3.37 eV and a large exciton binding energy of 60 meV at room temperature, which make it a promising candidate for optoelectronic devices such as blue-light emitting diodes, ultraviolet laser diodes and photodiodes. Recently, there have been tremendous interests in ZnO nanowire arrays. It is well known that one of the biggest challenges toward good ZnO-based optoelectronic devices is ...

  16. ZnO nanowire arrays with and without cavity tops

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongyu; Quan Baogang; Tang Haoying; Guo Chuanfei [National Center for Nanoscience and Technology, Beijing 100190 (China); Jiang Peng, E-mail: pjiang@nanoctr.cn [National Center for Nanoscience and Technology, Beijing 100190 (China); Yu Aifang [National Center for Nanoscience and Technology, Beijing 100190 (China); Xie Sishen, E-mail: ssxie@aphy.iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190 (China); Wang Zhonglin, E-mail: zhong.wang@mse.gatech.edu [National Center for Nanoscience and Technology, Beijing 100190 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2011-10-03

    Highlights: {yields} ZnO NW array structure was formed on a ZnO-seed-layer-patterned Si substrate. {yields} Both e-beam lithography and a wet chemical method were employed. {yields} A bubble-assisted method was used for constructing ZnO nanowire arrays with cavity tops. {yields} ZnO NW array structures with different morphologies exhibited different photoluminescence properties. - Abstract: We report a new bubble-assisted growing and etching method for constructing ZnO nanowire (NW) arrays with cavity tops. Firstly, a ZnO NW array structure was formed on a ZnO-seed-layer-patterned Si substrate by combining e-beam lithography and a wet chemical method. Secondly, a new kind of ZnO NW array with cavity tops could be formed by a subsequent bubble-assisted growing and etching. These ZnO NW array structures with different morphologies exhibited different photoluminescence properties, showing their potential applications in lasing cavities, stimulated emitters, nanogenerator, photocatalysis and light-emitting diodes. The bubble-assisted etching method will open a new door for morphology design of ZnO and other semiconductor nanowire arrays at special sites.

  17. Cavity modes of tapered ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xiulai; Brossard, Frederic S F; Williams, David A [Hitachi Cambridge Laboratory, Hitachi Europe Ltd, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Collins, Daniel P; Holmes, Mark J; Taylor, Robert A [Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Zhang Xitian, E-mail: xx757@cam.ac.u, E-mail: xtzhangzhang@hotmail.co [Heilongjiang Key Laboratory for Advanced Functional Materials and Excited State Processes, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025 (China)

    2010-08-15

    We report on a cavity mode mapping of ZnO tapered nanowires using micro-photoluminescence spectroscopy at room temperature. Both the Fabry-Perot (FP) and the whispering gallery (WG) modes are identified in a single wire. The emission spectra from single nanowires comprise regular Lorentzian peaks, which arise from the FP interference between the ends of the nanowire. The overall intensity along the tapered wire varies periodically. This variation is ascribed to WG mode resonances across the nanowire. The results agree well with the theoretical calculations using the finite-difference time-domain method.

  18. Growth of ZnO nanowires on nonwoven polyethylene fibers

    Directory of Open Access Journals (Sweden)

    Sunandan Baruah et al

    2008-01-01

    Full Text Available We report the growth of ZnO nanowires on nonwoven polyethylene fibers using a simple hydrothermal method at a temperature below the boiling point of water. The ZnO nanowires were grown from seed ZnO nanoparticles affixed onto the fibers. The seed ZnO nanoparticles, with diameters of about 6–7 nm, were synthesized in isopropanol by reducing zinc acetate hydrate with sodium hydroxide. The growth process was carried out in a sealed chemical bath containing an equimolar solution of zinc nitrate hexahydrate and hexamethylene tetramine at a temperature of 95 °C over a period of up to 20 h. The thickness and length of the nanowires can be controlled by using different concentrations of the starting reactants and growth durations. A 0.5 mM chemical bath yielded nanowires with an average diameter of around 50 nm, while a 25 mM bath resulted in wires with a thickness of up to about 1 μm. The length of the wires depends both on the concentration of the precursor solution as well as the growth duration, and in 20 h, nanowires as long as 10 μm can be grown. The nonwoven mesh of polyethylene fibers covered with ZnO nanowires can be used for novel applications such as water treatment by degrading pollutants by photocatalysis. Photocatalysis tests carried out on standard test contaminants revealed that the polyethylene fibers with ZnO nanowires grown on them could accelerate the photocatalytic degradation process by a factor of 3.

  19. Growth of ZnO nanowires on nonwoven polyethylene fibers

    Science.gov (United States)

    Baruah, Sunandan; Thanachayanont, Chanchana; Dutta, Joydeep

    2008-01-01

    We report the growth of ZnO nanowires on nonwoven polyethylene fibers using a simple hydrothermal method at a temperature below the boiling point of water. The ZnO nanowires were grown from seed ZnO nanoparticles affixed onto the fibers. The seed ZnO nanoparticles, with diameters of about 6–7 nm, were synthesized in isopropanol by reducing zinc acetate hydrate with sodium hydroxide. The growth process was carried out in a sealed chemical bath containing an equimolar solution of zinc nitrate hexahydrate and hexamethylene tetramine at a temperature of 95 °C over a period of up to 20 h. The thickness and length of the nanowires can be controlled by using different concentrations of the starting reactants and growth durations. A 0.5 mM chemical bath yielded nanowires with an average diameter of around 50 nm, while a 25 mM bath resulted in wires with a thickness of up to about 1 μm. The length of the wires depends both on the concentration of the precursor solution as well as the growth duration, and in 20 h, nanowires as long as 10 μm can be grown. The nonwoven mesh of polyethylene fibers covered with ZnO nanowires can be used for novel applications such as water treatment by degrading pollutants by photocatalysis. Photocatalysis tests carried out on standard test contaminants revealed that the polyethylene fibers with ZnO nanowires grown on them could accelerate the photocatalytic degradation process by a factor of 3. PMID:27877984

  20. Materialization of single multicomposite nanowire: entrapment of ZnO nanoparticles in polyaniline nanowire

    Directory of Open Access Journals (Sweden)

    Park Seong

    2011-01-01

    Full Text Available Abstract We present materialization of single multicomposite nanowire (SMNW-entrapped ZnO nanoparticles (NPs via an electrochemical growth method, which is a newly developed fabrication method to grow a single nanowire between a pair of pre-patterned electrodes. Entrapment of ZnO NPs was controlled via different conditions of SMNW fabrication such as an applied potential and mixture ratio of NPs and aniline solution. The controlled concentration of ZnO NP results in changes in the physical properties of the SMNWs, as shown in transmission electron microscopy images. Furthermore, the electrical conductivity and elasticity of SMNWs show improvement over those of pure polyaniline nanowire. The new nano-multicomposite material showed synergistic effects on mechanical and electrical properties, with logarithmical change and saturation increasing ZnO NP concentration.

  1. ZnO nanowire arrays - Pattern generation, growth and applications

    Energy Technology Data Exchange (ETDEWEB)

    Zacharias, Margit; Subannajui, Kittitat; Menzel, Andreas; Yang, Yang [Faculty of Engineering, Nanotechnology, Institute of Microsystems Engineering (IMTEK), Albert Ludwigs University, Freiburg (Germany)

    2010-10-15

    ZnO nanowires and related materials are in the focus of attention for electronic, optical or sensor applications. However, size, position and arrangement control are essential conditions for the development of future nanowire based devices. Various kinds of template methods including nanosphere lithography and UV laser interference lithography are powerful tools for the preparation of the starting metal catalyst arrays and will be demonstrated and discussed. However, only if the growth mechanism and its guiding parameters are understood in detail, the template will force a pattern arranged growth of nanowires. The paper gives an overview of the various kinds of growth modes for vertical arranged nanowires. Specific experimental conditions establishing the VS or the VLS growth are discussed. In addition, insight is given why the patterning is not all the time conserved and how to overcome these obstacles. In the second part different kinds of applications are summarized. Electronic properties are discussed based on metal-semiconductor-metal devices. The influence of a core-shell nanowire structure on the optical properties is demonstrated. In addition, a simple approach for ZnO nanowire based gas sensors is discussed and shown. As a last example, the transfer of Al{sub 2}O{sub 3} coated nanowires into spinel tubes is reported. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. Effect of growth temperature on photoluminescence and piezoelectric characteristics of ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Water, Walter [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China); Fang, T.-H. [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China); Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China)], E-mail: fang.tehua@msa.hinet.net; Ji, L.-W.; Lee, C.-C. [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China)

    2009-02-25

    ZnO nanowire arrays were synthesized on Au-coated silicon (1 0 0) substrates by using vapour-liquid-solid process in this work. The effect of growth temperatures on the crystal structure and the surface morphology of ZnO nanowires were investigated by X-ray diffraction and scanning electron microscope. The absorption and optical characteristics of the nanowires were examined by Ultraviolet/Visible spectroscopy, and photoluminescence, respectively. The photoluminescence results exhibited ZnO nanowires had an ultraviolet and blue emission at 383 and 492 nm. Then a nanogenerator with ZnO nanowire arrays was fabricated and demonstrated Schottky-like current-voltage characteristics.

  3. Effect of Intrinsic Point Defect on the Magnetic Properties of ZnO Nanowire

    OpenAIRE

    Jiangni Yun; Zhiyong Zhang; Tieen Yin

    2013-01-01

    The effect of intrinsic point defect on the magnetic properties of ZnO nanowire is investigated by the first-principles calculation based on the density functional theory (DFT). The calculated results reveal that the pure ZnO nanowire without intrinsic point defect is nonmagnetic and ZnO nanowire with VO, Zni, Oi, OZn, or ZnO point defect also is nonmagnetic. However, a strong spin splitting phenomenon is observed in ZnO nanowire with VZn defect sitting on the surface site. The Mulliken popul...

  4. Biofunctionalization of ZnO nanowires for DNA sensory applications

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Ulrich Christian; Gnauck, Martin; Ronning, Carsten [Institute of Solid State Physics, University of Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Moeller, Robert; Rudolph, Bettina; Fritzsche, Wolfgang [Institut fuer Photonische Technologien e.V., Albert-Einstein-Strasse 9, D-07745 Jena (Germany)

    2011-07-01

    In recent years, DNA detecting systems have received a growing interest due to promising fields of application like DNA diagnostics, gene analysis, virus detection or forensic applications. Nanowire-based DNA biosensor allows both miniaturization and easy continuous monitoring of a detection signal by electrical means. The label free detection scheme based on electrochemical changes of the surface potential during immobilization of specific DNA probes was heretofore mainly studied for silicon. In this work a surface decoration process with bifunctional molecules known as silanization was applied to VLS-grown ZnO nanowires which both feature a large sensitivity for surface modification, are biocompatible and easy to synthesize as well. Successfully bound DNA was proved by fluorescence microscopy. Dielectrophoresis (DEP) was chosen and optimized for quickly contacting the ZnO nanowires. Furthermore, electrical signal characterization was performed in preparation for DNA sensory applications.

  5. UV irradiation assisted growth of ZnO nanowires on optical fiber surface

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Bo; Shi, Tielin; Liao, Guanglan; Li, Xiaoping; Huang, Jie; Zhou, Temgyuan; Tang, Zirong, E-mail: zirong@mail.hust.edu.cn

    2017-06-01

    Highlights: • A new fabrication process combined a hydrothermal process with UV irradiation from optical fiber is developed. • The growth of ZnO nanowires is efficient in the utilization of UV light. • A novel hybrid structure which integrates ZnO nanowires on optical fiber surface is synthesized. • The UV assisted growth of ZnO nanowires shows preferred orientation and better quality. • A mechanism of growing ZnO nanowires under UV irradiation is proposed. - Abstract: In this paper, a novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface. The method combined a hydrothermal process with the efficient UV irradiation from the fiber core, and the effects of UV irradiation on the growth behavior of ZnO nanowires were investigated. The results show that UV irradiation had great effects on the preferred growth orientation and the quality of the ZnO nanowires. The crystallization velocity along the c-axis would increase rapidly with the increase of the irradiation power, while the growth process in the lateral direction was marginally affected by the irradiation. The structure of ZnO nanowires also shows less oxygen vacancy with UV irradiation of higher power. The developed approach is applicable for the efficient growth of nanowires on the fiber surface, and the ZnO nanowires/optical fiber hybrid structures have great potentials for a wide variety of applications such as optical fiber sensors and probes.

  6. Optical Properties of Indium Doeped ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    Tsung-Shine Ko

    2015-01-01

    Full Text Available We report the synthesis of the ZnO nanowires (NWs with different indium concentrations by using the thermal evaporation method. The gold nanoparticles were used as the catalyst and were dispersed on the silicon wafer to facilitate the growth of the ZnO NWs. High resolution transmission electron microscopy confirms that the ZnO NWs growth relied on vapor-liquid-solid mechanism and energy dispersion spectrum detects the atomic percentages of indium in ZnO NWs. Scanning electron microscopy shows that the diameters of pure ZnO NWs range from 20 to 30 nm and the diameters of ZnO:In were increased to 50–80 nm with increasing indium doping level. X-ray diffraction results point out that the crystal quality of the ZnO NWs was worse with doping higher indium concentration. Photoluminescence (PL study of the ZnO NWs exhibited main photoemission at 380 nm due to the recombination of excitons in near-band-edge (NBE. In addition, PL results also indicate the slightly blue shift and PL intensity decreasing of NBE emission from the ZnO NWs with higher indium concentrations could be attributed to more donor-induced trap center generations.

  7. Oligo and Poly-thiophene/Zno Hybrid Nanowire Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Briseno, Alejandro L.; Holcombe, Thomas W.; Boukai, Akram I.; Garnett, Erik C.; Shelton, Steve W.; Frechet, Jean J. M.; Yang, Peidong

    2009-11-03

    We demonstrate the basic operation of an organic/inorganic hybrid single nanowire solar cell. End-functionalized oligo- and polythiophenes were grafted onto ZnO nanowires to produce p-n heterojunction nanowires. The hybrid nanostructures were characterized via absorption and electron microscopy to determine the optoelectronic properties and to probe the morphology at the organic/inorganic interface. Individual nanowire solar cell devices exhibited well-resolved characteristics with efficiencies as high as 0.036percent, Jsc = 0.32 mA/cm2, Voc = 0.4 V, and a FF = 0.28 under AM 1.5 illumination with 100 mW/cm2 light intensity. These individual test structures will enable detailed analysis to be carried out in areas that have been difficult to study in bulk heterojunction devices.

  8. Recent Progress in Ohmic/Schottky-Contacted ZnO Nanowire Sensors

    National Research Council Canada - National Science Library

    Zhao, Xiaoli; Zhou, Ranran; Hua, Qilin; Dong, Lin; Yu, Ruomeng; Pan, Caofeng

    2015-01-01

      We review the recent progress of zinc oxide (ZnO) nanowire sensors with ohmic-contacted and Schottky-contacted configurations and the enhancement of the performances of Schottky-contacted ZnO NW sensors (SCZNSs...

  9. Synthesis, optical and electrochemical properties of ZnO nanowires/graphene oxide heterostructures

    National Research Council Canada - National Science Library

    Zeng, Huidan; Cao, Ying; Xie, Shufan; Yang, Junhe; Tang, Zhihong; Wang, Xianying; Sun, Luyi

    2013-01-01

    .... Electrochemical property measurement results demonstrated that the ZnO nanowires/graphene oxide have large integral area of cyclic voltammetry loop, indicating that such heterostructure is promising...

  10. Surface effects on photoluminescence of single ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Liao Zhimin [State Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871 (China); Zhang Hongzhou [Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, Australian National University, ACT 0200 (Australia); Zhou Yangbo; Xu Jun; Zhang Jingmin [State Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871 (China); Yu Dapeng [State Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871 (China)], E-mail: yudp@pku.edu.cn

    2008-06-09

    The influence of surface effects on the temperature dependent photoluminescence (PL) spectra from individual ZnO nanowires has been studied. It is found that the surface effects of the nanowire are very important in both ultraviolet (UV) and visible emission. We propose a new luminescence mechanism based on the recombination related to oxygen vacancies to explain the temperature dependent visible emission, which is significantly influenced by the carrier depletion and band bending caused by surface effects. In addition, the observed attenuation of UV emission with increasing temperature is ascribed to the decreasing depletion region and the increasing surface states related nonradiative recombination.

  11. Selective area growth of well-ordered ZnO nanowire arrays with controllable polarity.

    Science.gov (United States)

    Consonni, Vincent; Sarigiannidou, Eirini; Appert, Estelle; Bocheux, Amandine; Guillemin, Sophie; Donatini, Fabrice; Robin, Ivan-Christophe; Kioseoglou, Joseph; Robaut, Florence

    2014-05-27

    Controlling the polarity of ZnO nanowires in addition to the uniformity of their structural morphology in terms of position, vertical alignment, length, diameter, and period is still a technological and fundamental challenge for real-world device integration. In order to tackle this issue, we specifically combine the selective area growth on prepatterned polar c-plane ZnO single crystals using electron-beam lithography, with the chemical bath deposition. The formation of ZnO nanowires with a highly controlled structural morphology and a high optical quality is demonstrated over large surface areas on both polar c-plane ZnO single crystals. Importantly, the polarity of ZnO nanowires can be switched from O- to Zn-polar, depending on the polarity of prepatterned ZnO single crystals. This indicates that no fundamental limitations prevent ZnO nanowires from being O- or Zn-polar. In contrast to their catalyst-free growth by vapor-phase deposition techniques, the possibility to control the polarity of ZnO nanowires grown in solution is remarkable, further showing the strong interest in the chemical bath deposition and hydrothermal techniques. The single O- and Zn-polar ZnO nanowires additionally exhibit distinctive cathodoluminescence spectra. To a broader extent, these findings open the way to the ultimate fabrication of well-organized heterostructures made from ZnO nanowires, which can act as building blocks in a large number of electronic, optoelectronic, and photovoltaic devices.

  12. Tunable electronic transport characteristics of surface-architecture-controlled ZnO nanowire field effect transistors.

    Science.gov (United States)

    Hong, Woong-Ki; Sohn, Jung Inn; Hwang, Dae-Kue; Kwon, Soon-Shin; Jo, Gunho; Song, Sunghoon; Kim, Seong-Min; Ko, Hang-Ju; Park, Seong-Ju; Welland, Mark E; Lee, Takhee

    2008-03-01

    Surface-architecture-controlled ZnO nanowires were grown using a vapor transport method on various ZnO buffer film coated c-plane sapphire substrates with or without Au catalysts. The ZnO nanowires that were grown showed two different types of geometric properties: corrugated ZnO nanowires having a relatively smaller diameter and a strong deep-level emission photoluminescence (PL) peak and smooth ZnO nanowires having a relatively larger diameter and a weak deep-level emission PL peak. The surface morphology and size-dependent tunable electronic transport properties of the ZnO nanowires were characterized using a nanowire field effect transistor (FET) device structure. The FETs made from smooth ZnO nanowires with a larger diameter exhibited negative threshold voltages, indicating n-channel depletion-mode behavior, whereas those made from corrugated ZnO nanowires with a smaller diameter had positive threshold voltages, indicating n-channel enhancement-mode behavior.

  13. Physical and Electrical Performance of Vapor–Solid Grown ZnO Straight Nanowires

    Directory of Open Access Journals (Sweden)

    Li H

    2008-01-01

    Full Text Available Abstract Physical and electrical properties of wurtzitic ZnO straight nanowires grown via a vapor–solid mechanism were investigated. Raman spectrum shows four first-order phonon frequencies and a second-order Raman frequency of the ZnO nanowires. Electrical and photoconductive performance of individual ZnO straight nanowire devices was studied. The results indicate that the nanowires reported here are n-type semi-conductors and UV light sensitive, and a desirable candidate for fabricating UV light nanosensors and other applications.

  14. Effect of Ga-doping on the properties of ZnO nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Ishiyama, Takeshi, E-mail: ishiyama@ee.tut.ac.jp; Nakane, Takaya, E-mail: ishiyama@ee.tut.ac.jp; Fujii, Tsutomu, E-mail: ishiyama@ee.tut.ac.jp [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan)

    2015-02-27

    Arrays of single-crystal zinc oxide (ZnO) nanowires have been synthesized on silicon substrates by vapor-liquid-solid growth techniques. The effect of growth conditions including substrate temperature and Ar gas flow rate on growth properties of ZnO nanowire arrays were studied. Structural and optical characterization was performed using scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. SEM images of the ZnO nanowire arrays grown at various Ar gas flow rates indicated that the alignment and structural features of ZnO nanowires were affected by the gas flow rate. The PL of the ZnO nanowire arrays exhibited strong ultraviolet (UV) emission at 380 nm and green emission around 510 nm. Moreover, the green emission reduced in Ga-doped sample.

  15. Controlled growth of vertically aligned ZnO nanowires with different crystal orientation of the ZnO seed layer

    Science.gov (United States)

    Cha, S. N.; Song, B. G.; Jang, J. E.; Jung, J. E.; Han, I. T.; Ha, J. H.; Hong, J. P.; Kang, D. J.; Kim, J. M.

    2008-06-01

    A novel synthesis and growth method achieving vertically aligned zinc oxide (ZnO) nanowires on a silicon dioxide (SiO2) coated silicon (Si) substrate is demonstrated. The growth direction of the ZnO nanowires is determined by the crystal structure of the ZnO seed layer, which is formed by the oxidation of a DC-sputtered Zn film. The [002] crystal direction of the seed layer is dominant under optimized thickness of the Zn film and thermal treatment. Vertically aligned ZnO nanowires on SiO2 coated Si substrate are realized from the appropriately thick oxidized Zn seed layer by a vapor-solid growth mechanism by catalyst-free thermal chemical vapor deposition (CVD). These experimental results raise the possibility of using the nanowires as functional blocks for high-density integration systems and/or photonic applications.

  16. Effect of Intrinsic Point Defect on the Magnetic Properties of ZnO Nanowire

    Directory of Open Access Journals (Sweden)

    Jiangni Yun

    2013-01-01

    Full Text Available The effect of intrinsic point defect on the magnetic properties of ZnO nanowire is investigated by the first-principles calculation based on the density functional theory (DFT. The calculated results reveal that the pure ZnO nanowire without intrinsic point defect is nonmagnetic and ZnO nanowire with VO, Zni, Oi, OZn, or ZnO point defect also is nonmagnetic. However, a strong spin splitting phenomenon is observed in ZnO nanowire with VZn defect sitting on the surface site. The Mulliken population analysis reveals that the oxygen atoms which are close to the VZn defect do major contribution to the magnetic moment. Partial density states calculation further suggests that the appearance of the half-metallic ferromagnetism in ZnO nanorod with VZn originates from the hybridization of the O2p states with Zn 3d states.

  17. Low temperature growth and optical properties of ZnO nanowires using an aqueous solution method.

    Science.gov (United States)

    Chu, Manh-Hung; Lee, Joon-Hyung; Kim, Jeong-Joo; Kim, Kyeong-Won; Norton, D P; Heo, Young-Woo

    2012-02-01

    ZnO nanowires were grown on indium tin oxide (ITO) coated glass substrates at a low temperature of 90 degrees C using an aqueous solution method. The ZnO seeds were coated on the ITO thin films by using a spin coater. ZnO nanowires were formed in an aqueous solution containing zinc nitrate hexahydrate (Zn(NO3)2 x 6H2O) and hexamethylenetetramine (C6H12N4). The pH value and concentration of the solution play an important role in the growth and morphologies of ZnO nanowires. The size of ZnO naonowires increased as the concentration of the solution increased. It was formed with a top surface of hexagonal and tapered shape at low and high pH values respectively. Additionally, the single crystalline structure and optical property of the ZnO nanowires were investigated using high-resolution transmission electron microscopy and photoluminescence spectroscopy.

  18. Photoluminescence characterization of ZnO nanowires functionalization

    Science.gov (United States)

    Politi, Jane; Gioffrè, Mariano; Rea, Ilaria; De Stefano, Luca; Rendina, Ivo

    2015-05-01

    Nanostructured photoluminescent materials are optimal transducers for optical biosensors due to their capacity to convert molecular interactions in light signals without contamination or deterioration of the samples. In recent years, nanostructured biosensors with low cost and readily available properties have been developed for such applications as therapeutics, diagnostic and environmental. Zinc oxide nanowires (ZnO NWs) is material with unique properties and due to these they were widely studied in many fields as electronics, optics, and photonics. ZnO NWs can be either grown independently or deposited on solid support, such as glass, gold substrates and crystalline silicon. Vertical aligned ZnO forest on a substrate shows specific advantages in photonic device fabrication. ZnO NWs are typically synthesized by such techniques classified as vapour phase and solution phase synthesis. In particular, hydrothermal methods have received a lot of attention and have been widely used for synthesis of ZnO NWs. This technique shows more crystalline defects than others due to oxygen vacancies, so as the material shows intense photoluminescence emission under laser irradiation. ZnO NWs surface is highly hydrolysed, so it is covered by OH reactive groups, and standard biomodification chemistry can be used in order to bind bioprobes on the surface. In this work, we present our newest results on synthetic nanostructured materials characterization for optical biosensors applications. In particular, we characterize the ZnO NWs structure grown on crystalline silicon by SEM images and the biomodification by photoluminesce technique, fluorescence microscopy, water contact angle and FT-IR measurements.

  19. Spontaneous ZnO nanowire formation during oxidation of Cu-Zn alloy

    Science.gov (United States)

    Yuan, Lu; Wang, Chao; Cai, Rongsheng; Wang, Yiqian; Zhou, Guangwen

    2013-07-01

    A combination of electron microscopy and in-situ x-ray diffraction is employed to study the thermal oxidation of brass (Cu0.7Zn0.3 alloy) in order to elucidate the mechanism of one-dimensional growth of ZnO nanostructures. Oxidation of the brass alloy results in the growth of a ZnO overlayer with ZnO nanowire formation on the ZnO layer. Increasing the oxidation temperature thickens the ZnO overlayer while suppressing ZnO nanowire formation on the top, which provides clear evidence that the formation of ZnO nanowires is related to a stress-driven mechanism that involves accumulation of compressive stress generated from the ZnO/Cu-Zn interfacial reaction and relaxation of the compressive stress by outward grain-boundary diffusion of Zn.

  20. Effect of indium concentration on luminescence and electrical properties of indium doped ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sin Yee [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Brahma, Sanjaya [Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Liu, Chuan-Pu [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Wang, Ruey-Chi [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan, ROC (China); Huang, Jow-Lay, E-mail: JLH888@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan, ROC (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2013-12-31

    In this work, indium (In) doped ZnO nanowires are grown on a Si substrate by chemical vapor deposition (CVD), at a relatively low temperature of 550 °C. The effects of In concentration on the morphology, microstructure, luminescence and electrical properties of ZnO nanowires are investigated. The diameters and lengths of these nanowires are in the ranges of 70–311 nm and 10–15 μm, respectively. These nanowires are single crystals growing in the [0001] direction. The maximum solubility of In in ZnO is estimated to be 3.47 at.%. Photoluminescence (PL) spectra reveal a red shift in the ultraviolet emission and intensity enhancement in the green emission with increasing indium doping concentration. Besides, carrier concentration, mobility and resistivity of the nanowires with different doping concentrations are determined based on single-nanowire field effect transistors (FET). - Highlights: • Indium (In) doped ZnO nanowires were grown by chemical vapor deposition at 550 °C. • In doping leads to an increase in the intensity of visible light emission. • Resistivity of the ZnO nanowire is lowered at high (3.47 at.%) In doping. • In doped ZnO nanowire field effect transistor (FET) was fabricated. • Mobility and carrier concentration were determined.

  1. Excitonic effects in ZnO nanowires and hollow nanotubes

    Science.gov (United States)

    Willander, M.; Lozovik, Y. E.; Zhao, Q. X.; Nur, O.; Hu, Q.-H.; Klason, P.

    2007-02-01

    Energy levels and wave functions of ground and excited states of an exciton are calculated by the method of imaginary time. Energy levels as functions of radius of single and double wall nanotube are studied. Asymptotic behavior of energy levels at large and small values of the radius using perturbation theory and adiabatic approximation is considered. Spatially indirect exciton in semiconductor nanowire is also investigated. Experimental result from high quality reproducible ZnO nanowires grown by low temperature chemical engineering is presented. State of the art high brightness white light emitting diodes (HB-LEDs) are demonstrated from the grown ZnO nano-wires. The color temperature and color rendering index (CRI) of the HB-LEDs values was found to be (3250 K, 82), and (14000 K, 93), for the best LEDs, which means that the quality of light is superior to one obtained from GaN LEDs available on the market today. The role of V Zn and V ° on the emission responsible for the white light band as well as the peak position of this important wide band is thoroughly investigated in a systematic way.

  2. Oxygen vacancy diffusion in bare ZnO nanowires

    Science.gov (United States)

    Deng, Bei; Luisa da Rosa, Andreia; Frauenheim, Th.; Xiao, J. P.; Shi, X. Q.; Zhang, R. Q.; van Hove, Michel A.

    2014-09-01

    Oxygen vacancies (VO) are known to be common native defects in zinc oxide (ZnO) and to play important roles in many applications. Based on density functional theory, we present a study for the migration of oxygen vacancies in ultra-thin ZnO nanowires (NWs). We find that under equilibrium growth conditions VO has a higher formation energy (Ef) inside the wire than that at shallow sites and surface sites, with different geometric relaxations and structural reconstructions. The migration of VO has lower barriers in the NW than in the bulk and is found to be energetically favorable in the direction from the bulk to the surface. These results imply a higher concentration of VO at surface sites and also a relative ease of diffusion in the NW structure. Our results support the previous experimental observations and are important for the development of ZnO-based devices in photocatalysis and optoelectronics.

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

    KAUST Repository

    Noriega, Rodrigo

    2009-08-18

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

  4. Hydrothermal Growth of ZnO Nanowires on UV-Nanoimprinted Polymer Structures.

    Science.gov (United States)

    Park, Sooyeon; Moore, Sean A; Lee, Jaejong; Song, In-Hyouk; Farshchian, Bahador; Kim, Namwon

    2018-05-01

    Integration of zinc oxide (ZnO) nanowires on miniaturized polymer structures can broaden its application in multi-functional polymer devices by taking advantages of unique physical properties of ZnO nanowires and recent development of polymer microstructures in analytical systems. In this paper, we demonstrate the hydrothermal growth of ZnO nanowires on polymer microstructures fabricated by UV nanoimprinting lithography (NIL) using a polyurethane acrylate (PUA). Since PUA is a siloxane-urethane-acrylate compound containing the alpha-hydroxyl ketone, UV-cured PUA include carboxyl groups, which inhibit and suppress the nucleation and growth of ZnO nanowires on polymer structures. The presence of carboxyl groups in UV-cured PUA was substantiated by Fourier transform infrared spectroscopy (FTIR), and a Ag thin film was deposited on the nanoimprinted polymer structures to limit their inhibitive influence on the growth of ZnO nanowires. Furthermore, the naturally oxidized Ag layer (Ag2O) reduced crystalline lattice mismatches at the interface between ZnO-Ag during the seed annealing process. The ZnO nanowires grown on the Ag-deposited PUA microstructures were found to have comparable morphological characteristics with ZnO nanowires grown on a Si wafer.

  5. Improved seedless hydrothermal synthesis of dense and ultralong ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tian Jinghua; Hu Jie; Li Sisi; Zhang Fan; Liu Jun; Shi Jian; Li Xin; Chen Yong [Ecole Normale Superieure, CNRS-ENS-UPMC UMR 8640, 24 rue Lhomond, 75005 Paris (France); Tian Zhongqun, E-mail: yong.chen@ens.fr [State Key Laboratory of Physical Chemistry of Solid Surfaces and LIA CNRS XiamENS ' NanoBioChem' , College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian (China)

    2011-06-17

    Seedless hydrothermal synthesis has been improved by introducing an adequate content of ammonia into the nutrient solution, allowing the fabrication of dense and ultralong ZnO nanowire arrays over large areas on a substrate. The presence of ammonia in the nutrient solution facilitates the high density nucleation of ZnO on the substrate which is critical for the nanowire growth. In order to achieve an optimal growth, the growth conditions have been studied systematically as a function of ammonia content, growth temperature and incubation time. The effect of polyethyleneimine (PEI) has also been studied but shown to be of no benefit to the nucleation of ZnO. Ultradense and ultralong ZnO nanowires could be obtained under optimal growth conditions, showing no fused structure at the foot of the nanowire arrays. Due to different reaction kinetics, four growth regimes could be attributed, including the first fast growth, equilibrium phase, second fast growth and final erosion. Combining this simple method with optical lithography, ZnO nanowires could be grown selectively on patterned areas. In addition, the as-grown ZnO nanowires could be used for the fabrication of a piezoelectric nanogenerator. Compared to the device of ZnO nanowires made by other methods, a more than twice voltage output has been obtained, thereby proving an improved performance of our growth method.

  6. Optical and morphological properties of graphene sheets decorated with ZnO nanowires via polyol enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Vinay, E-mail: winn201@gmail.com; Rajaura, Rajveer Singh, E-mail: winn201@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur - 302004 (India); Sharma, Preetam K.; Srivastava, Subodh; Vijay, Y. K. [Department of Physics, Thin Film and Membrane Science Lab., University of Rajasthan, Jaipur - 302004 (India); Sharma, S. S. [Department of Physics, Govt. Women Engineering College, Ajmer- 305002 (India)

    2014-04-24

    Graphene-ZnO nanocomposites have proven to be very useful materials for photovoltaic and sensor applications. Here, we report a facile, one-step in situ polymerization method for synthesis of graphene sheets randomly decorated with zinc oxide nanowires using ethylene glycol as solvent. We have used hydrothermal treatment for growth of ZnO nanowires. UV-visible spectra peak shifting around 288nm and 307 nm shows the presence of ZnO on graphene structure. Photoluminiscence spectra (PL) in 400nm-500nm region exhibits the luminescence quenching effect. Scanning electron microscopy (SEM) image confirms the growth of ZnO nanowires on graphene sheets.

  7. Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2Buffer Layers in Dye-Sensitized Solar Cells

    OpenAIRE

    Yang, Weiguang; Wan, Farong; Chen, Siwei; Jiang, Chunhua

    2009-01-01

    Abstract This paper reports the effects of the seed layers prepared by spin-coating and dip-coating methods on the morphology and density of ZnO nanowire arrays, thus on the performance of ZnO nanowire-based dye-sensitized solar cells (DSSCs). The nanowire films with the thick ZnO buffer layer (~0.8–1 μm thick) can improve the open circuit voltage of the DSSCs through suppressing carrier recombination, however, and cause the decrease of dye loading absorbed on ZnO nanowires. In ord...

  8. A ZnO nanowire bio-hybrid solar cell

    Science.gov (United States)

    Yaghoubi, Houman; Schaefer, Michael; Yaghoubi, Shayan; Jun, Daniel; Schlaf, Rudy; Beatty, J. Thomas; Takshi, Arash

    2017-02-01

    Harvesting solar energy as a carbon free source can be a promising solution to the energy crisis and environmental pollution. Biophotovoltaics seek to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. In the current study, we report on a combination of zinc oxide (ZnO) nanowires with monolayers of photosynthetic reaction centers which are self-assembled, via a cytochrome c linker, as photoactive electrode. In a three-probe biophotovoltaics cell, a photocurrent density of 5.5 μA cm-2 and photovoltage of 36 mV was achieved, using methyl viologen as a redox mediator in the electrolyte. Using ferrocene as a redox mediator a transient photocurrent density of 8.0 μA cm-2 was obtained, which stabilized at 6.4 μA cm-2 after 20 s. In-depth electronic structure characterization using photoemission spectroscopy in conjunction with electrochemical analysis suggests that the fabricated photoactive electrode can provide a proper electronic path for electron transport all the way from the conduction band of the ZnO nanowires, through the protein linker to the RC, and ultimately via redox mediator to the counter electrode.

  9. ZnO nanowire-based glucose biosensors with different coupling agents

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Juneui [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Lim, Sangwoo, E-mail: swlim@yonsei.ac.kr [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Fabrication of ZnO nanowire-based glucose biosensors using different coupling agents. Black-Right-Pointing-Pointer Highest sensitivity for (3-aminopropyl)methyldiethoxysilane-treated biosensor. Black-Right-Pointing-Pointer Larger amount of glucose oxidase and lower electron transfer resistance for (3-aminopropyl)methyldiethoxysilane-treated biosensor. - Abstract: ZnO-nanowire-based glucose biosensors were fabricated by immobilizing glucose oxidase (GOx) onto a linker attached to ZnO nanowires. Different coupling agents were used, namely (3-aminopropyl)trimethoxysilane (APTMS), (3-aminopropyl)triethoxysilane (APTES), and (3-aminopropyl)methyldiethoxysilane (APS), to increase the affinity of GOx binding to ZnO nanowires. The amount of GOx immobilized on the ZnO nanowires, the performance, sensitivity, and Michaelis-Menten constant of each biosensor, and the electron transfer resistance through the biosensor were all measured in order to investigate the effect of the coupling agent on the ZnO nanowire-based biosensor. Among the different biosensors, the APS-treated biosensor had the highest sensitivity (17.72 {mu}A cm{sup -2} mM{sup -1}) and the lowest Michaelis-Menten constant (1.37 mM). Since APS-treated ZnO nanowires showed the largest number of C-N groups and the lowest electron transfer resistance through the biosensor, we concluded that these properties were the key factors in the performance of APS-treated glucose biosensors.

  10. Realizing field-dependent conduction in ZnO nanowires without annealing

    Science.gov (United States)

    Burke-Govey, C. P.; Castanet, U.; Warring, H.; Nau, A.; Ruck, B. J.; Majimel, J.; Plank, N. O. V.

    2017-03-01

    We report on the low-temperature fabrication of field-effect transistors by bridging pre-patterned electrodes using ZnO nanowires grown in situ, which operate without requiring post-growth processing or annealing. The devices show good performance using as-grown nanowires, with on-off ratios of 105 and threshold voltages of 2 V. Electron microscopy shows the field-dependent nanowires hierarchically nucleate from larger ZnO nanorods, and both are oriented along a common c-axis. A high nanowire surface-to-volume ratio allows depleting electron traps on the nanowire surface to compensate intrinsic electron donors present throughout the nanowire bulk. This eliminates the need to reduce the electron concentration through high-temperature annealing, making the nanowires naturally field-dependent in their as-grown state.

  11. Surface effects and nonlinear optical properties of ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Tobias; Richters, Jan-Peter; Dev, Apurba [Institute of Solid State Physics, University of Bremen (Germany)

    2010-10-15

    This paper discusses the surface effects and nonlinear optical properties of ZnO nanowires. First, the influence of the large surface-to-volume ratio of the nanowires on their photoluminescence properties is shown. The occurrence of a surface-exciton emission line is demonstrated and its properties are studied in time-integrated and time-resolved photoluminescence measurements. It is further demonstrated that this band is sensitive to surface modifications of the nanowires, such as dielectric and metallic coatings. It is shown that hydrogen can passivate deep defects in ZnO nanowires thereby reducing the defect luminescence and strongly enhancing the near-band-edge excitonic luminescence. The photoluminescence properties of chemically synthesized ZnO nanowires are compared to those of nanowires grown by vapor-transport techniques. The non-linear coefficients of chemically synthesized nanowires are analyzed, and first preliminary measurements of the optical gain of a ZnO nanowire waveguide are analyzed. Zincoxide nanowires under optical excitation. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. One-dimensional (1D) ZnO nanowires dye sensitized solar cell.

    Science.gov (United States)

    Kiliç, Bayram; Wang, Lianzhou; Ozdemir, Orhan; Lu, Max; Tüzemen, Sebahattin

    2013-01-01

    High ordered one-dimensional (1D) Zinc oxide (ZnO) nanowires were grown on FTO substrate by using the hydrothermal method. Nanowires structures were used as the wide band-gap semiconducting photo-electrode in dye sensitized solar cell (DSSCs). Solar cell made from ZnO nanowire at 50 nm radius and several tens micron lengths showed high solar conversion efficiency (eta) of 2.1% and incident photon current efficiency (IPCE) 35% using nanowire/N719 dye/I-/I3- electrolyte. We also compared Ru N719 dye and N3 dye on ZnO nanowire against each other in respect to solar conversion efficiency and IPCE measurements. In the case of the N3 dye on ZnO nanowire conversion efficiency (eta) of 1.32% and IPCE 23% were obtained under an illumination of 100 mW/cm2. It was found that the performance of the Ru N719 dyes was better than about 50% that of the N3 dye in ZnO nanowire dye-sensitized solar cells.

  13. Controlled synthesis of ultrathin ZnO nanowires using micellar gold nanoparticles as catalyst templates

    Science.gov (United States)

    YinPresent Address: State Key Lab Of Superhard Materials, Jilin University, Changchun, 130012, P. R. China., Hong; Wang, Qiushi; Geburt, Sebastian; Milz, Steffen; Ruttens, Bart; Degutis, Giedrius; D'Haen, Jan; Shan, Lianchen; Punniyakoti, Sathya; D'Olieslaeger, Marc; Wagner, Patrick; Ronning, Carsten; Boyen, Hans-Gerd

    2013-07-01

    We demonstrate a simple and effective approach to control the diameter of ultrathin ZnO nanowires with high aspect ratios and high densities over large areas. Diblock copolymer-based nanoparticle arrays exhibiting a high degree of hexagonal order and offering easy control of particle size (typically 1-10 nm) and interparticle spacing (25-150 nm) are utilized as nanocatalysts for the subsequent growth of semiconductor nanowires. The as-grown ZnO nanowires exhibit a single crystal hexagonal wurtzite structure and grow along the [0002] direction. Facetted catalyst particles were observed at the tip of the nanowires after synthesis, thus suggesting a catalyst-assisted vapor-solid-solid (VSS) rather than a vapor-liquid-solid (VLS) growth mechanism, the latter being frequently used in semiconductor nanowire production. Such a growth process allows us to easily prepare ultrathin ZnO nanowires with tunable diameters well below 10 nm by taking advantage of the inherent size control of the micellar method during deposition of the catalyst nanoparticles. Raman spectroscopy reveals a phonon confinement effect as the diameter of nanowires decreases. Photoluminescence spectra of these ultrathin nanowires indicate a blue shift of the free excitons and their phonon replicas by 37 meV induced by quantum confinement.We demonstrate a simple and effective approach to control the diameter of ultrathin ZnO nanowires with high aspect ratios and high densities over large areas. Diblock copolymer-based nanoparticle arrays exhibiting a high degree of hexagonal order and offering easy control of particle size (typically 1-10 nm) and interparticle spacing (25-150 nm) are utilized as nanocatalysts for the subsequent growth of semiconductor nanowires. The as-grown ZnO nanowires exhibit a single crystal hexagonal wurtzite structure and grow along the [0002] direction. Facetted catalyst particles were observed at the tip of the nanowires after synthesis, thus suggesting a catalyst-assisted vapor

  14. Using the hydrothermal method to grow p-type ZnO nanowires on Al-doped ZnO thin film to fabricate a homojunction diode.

    Science.gov (United States)

    Tseng, Yung-Kuan; Hung, Meng-Chun; Su, Shun-Lung; Li, Sheng-Kai

    2014-10-01

    In this study, the hydrothermal method is used to grow phosphorus-doped ZnO nanowires on Si/SiO2 substrates deposited with Al-doped ZnO thin film. This structure forms a homogeneous p-n junction. In this study, we are the pioneers to use ammonium hypophosphite (NH4H2PO2) as a source of phosphorus to prepare the precursor solution. Ammonium hypophosphite of different concentration levels is used to observe its effects on the growth of nanowires. The results show that the precursor solution prepared from ammonium hypophosphite can produce good crystalline ZnO nanowires while there is no linear relationship between the amounts and concentration levels of phosphorus doped into the nanowires. Whether the phosphorus-doped ZnO nanowires have the characteristics of a p-type semiconductor is indirectly verified by measuring whether the p-n junction made up of Al-doped ZnO thin film and phosphorus-doped ZnO nanowires shows rectifying behavior. I-V measurements are made on the specimens. The results show good rectifying behavior, proving that the phosphorus-doped ZnO nanowires and Al-doped AZO films have p-type and n-type semiconductor properties, constituting a good p-n junction. This result also proves that ammonium hypophosphite is a better source of phosphorus in the hydrothermal method to synthesize phosphorus-doped ZnO nanowires.

  15. Nature of sub-band gap luminescent eigenmodes in a ZnO nanowire

    NARCIS (Netherlands)

    Rühle, S.|info:eu-repo/dai/nl/31407659X; van Vugt, L.K.|info:eu-repo/dai/nl/338773800; Li, H.-Y.; Keizer, N.A.; Kuipers, L.; Vanmaekelbergh, D.A.M.|info:eu-repo/dai/nl/304829137

    2008-01-01

    The emission spectrum of individual high-quality ZnO nanowires consists of a series of Fabry-Pérot-like eigenmodes that extend far below the band gap of ZnO. Spatially resolved luminescence spectroscopy shows that light is emitted predominantly at both wire ends, with identical spectra reflecting

  16. Vertically integrated nanogenerator based on ZnO nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Aifang; Li, Hongyu; Tang, Haoying; Liu, Tengjiao; Jiang, Peng [National Center for Nanoscience and Technology, No.11, Beiyitiao Zhongguancun, Beijing 100190 (China); Wang, Zhong Lin [National Center for Nanoscience and Technology, No.11, Beiyitiao Zhongguancun, Beijing 100190 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2011-04-15

    We report a technique to construct a vertically integrated nanogenerator (VI-NG) based on ZnO nanowire (NW) arrays. The VI-NG consists of nine single NGs connected mixed parallel and serial by a layer-by-layer stacking. For the single layer NG, the peak output voltage and current are 0.045 V and 2.5 nA, respectively. The VI-NG produces an output power density of 2.8 nW/cm{sup 2} with a peak output voltage of 0.15 V and output current of 7.2 nA. The vertical integration of the multi-NG provides a feasible technique for effectively converting mechanical energies to electricity from environment. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Electrochemical growth of ZnO nanowires inside nanoporous alumina templates. A comparison with metallic Zn nanowires growth

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Daniel [Instituto de Quimica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Laboratoire d' Electrochimie et Chimie Analytique (UMR CNRS 7575), Ecole Nationale Superieure de Chimie de Paris (ENSCP) (France); Pauporte, Thierry; Lincot, Daniel [Laboratoire d' Electrochimie et Chimie Analytique (UMR CNRS 7575), Ecole Nationale Superieure de Chimie de Paris (ENSCP) (France); Gomez, Humberto [Instituto de Quimica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile)

    2008-10-15

    Molecular oxygen reduction in presence of Zn(II) allowed to get arrays of zinc oxide (ZnO) nanowires (NWs) inside thick anodic alumina membranes (AAM), previously made by anodization in oxalic acid. A Zinc (Zn) NWs array made by electrochemical deposition (ED) was employed as a metal reference in order to compare its growth behavior with respect to that of ZnO, a semiconducting material. Chronoamperometric measurements for Zn NWs showed a typical response for metallic growth inside porous templates while ZnO NWs did not show this behavior. We observed that Zn NWs grew faster than ZnO NWs as checked by the electrical charge. SEM images showed the presence of ZnO NWs only after long deposition time. X-ray diffraction data confirmed the ZnO structure. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    Science.gov (United States)

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  19. Improved performance of ZnO nanowire field-effect transistors via focused ion beam treatment

    Energy Technology Data Exchange (ETDEWEB)

    Liao Zhimin; Lu Yi; Bie Yaqing; Zhou Yangbo; Yu Dapeng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Wu Hanchun, E-mail: liaozm@pku.edu.cn, E-mail: wuhc@tcd.ie, E-mail: yudp@pku.edu.cn [School of Physics and CRANN, Trinity College Dublin, Dublin 2 (Ireland)

    2011-09-16

    A seven orders of magnitude increase in the current on/off ratio of ZnO nanowire field-effect transistors (FETs) after Ga{sup +} irradiation was observed. Transmission electron microscopy characterization revealed that the surface crystal quality of the ZnO nanowire was improved via the Ga{sup +} treatment. The Ga{sup +} irradiation efficiently reduces chemisorption effects and decreases oxygen vacancies in the surface layer. The enhanced performance of the nanowire FET was attributed to the decrease of surface trapped electrons and the decrease in carrier concentration.

  20. Epitaxial growth of znO nanowires over the ZnO thin films deposited on the Si and sapphire substrates.

    Science.gov (United States)

    Park, No-Kuk; Lee, You Jin; Jung, Ji Young; Lee, Won Guen; Bae, Young Je; Yoon, Suk Hoon; Han, Gi Bo; Ryu, Si Ok; Lee, Tae Jin

    2008-09-01

    Epitaxial growth of ZnO nanowires was carried out using a modified thermal evaporation method with inexpensive experimental setup. ZnO nanowires were synthesized using ZnO thin films. The ZnO thin films were deposited as a buffer layer on silicon and sapphire using an impinging flow reactor (IFR). The IFR system is a modified version of a chemical bath deposition (CBD). Films can be created at low temperature, without any metallic catalysts. The properties of Zinc Oxide films are dependant upon the type of substrate used. The same deposition process with a different substrates yields two films with different properties. The most critical effect on growth of ZnO nanowires were dependent the properties of the buffer layer deposited on the substrate. It was not the type of substrate used. A cost-efficient method for epitaxial growth of single crystal ZnO nanowires is proposed in this work.

  1. DNA-templated synthesis of ZnO thin layers and nanowires.

    Science.gov (United States)

    Atanasova, Petia; Weitz, R Thomas; Gerstel, Peter; Srot, Vesna; Kopold, Peter; van Aken, Peter A; Burghard, Marko; Bill, Joachim

    2009-09-09

    In this paper, we report a novel synthetic approach towards electrically conductive ZnO nanowires close to ambient conditions using lambda-DNA as a template. Initially, the suitability of DNA to assemble ZnO nanocrystals into thin coatings was investigated. The ZnO nanowires formed on stretched and aligned lambda-DNA molecules were prepared via chemical bath deposition (CBD) of zinc acetate in methanol solution in the presence of polyvinylpyrrolidone (PVP). After 10 deposition cycles, the nanowires exceed 10 microm in length and the height can be varied from 12 to around 40 nm. The nanocrystalline structure of the ZnO wires was confirmed by high-resolution transmission electron microscopy (HRTEM). The electrical conductivity was found to be of the order of several Omega cm at room temperature in two terminal measurements.

  2. Synthesis and functionalization study of hierarchical ZnO nanowires for potential nitroaromatic sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Anurag; Kim, Bruce C. [The University of Alabama, Tuscaloosa, AL (United States); Edwards, Eugene; Brantley, Christina; Ruffin, Paul [U.S. Army, RDECOM/AMRDEC, Redstone Arsenal, AL (United States)

    2012-06-15

    In this work, we synthesize hierarchical ZnO nanowires in a customized atmospheric CVD furnace and investigate their surface modification behavior for prospective nitroaromatic sensing applications. The morphology and crystal structure of pristine nanowires are characterized through FE-SEM, TEM, X-ray diffraction and EDAX studies. Photoluminescence behavior of pristine nanowires is also reported. Surface modification behavior of synthesized nanowires on a ZnO-oleic acid system is studied by utilizing Raman and FT-IR spectroscopy. Based on these findings, 1-pyrenebutyric acid (PBA) has been identified as an appropriate fluorescent receptor for sensing p-nitrophenol. Fluorescence quenching experiments on a PBA-p-nitrophenol system are reported and a detection limit of up to 28 ppb is envisaged for PBA-grafted ZnO nanowire-based optical sensor. (orig.)

  3. Synthesis of ZnO Nanowires and Their Photovoltaic Application: ZnO Nanowires/AgGaSe2 Thin Film Core-Shell Solar Cell

    Directory of Open Access Journals (Sweden)

    Elif Peksu

    2015-01-01

    Full Text Available In this investigation, hydrothermal technique was employed for the synthesis of well-aligned dense arrays of ZnO nanowires (NWs on a wide range of substrates including silicon, soda-lime glass (SLG, indium tin oxide, and polyethylene terephthalate (PET. Results showed that ZnO NWs can be successfully grown on any substrate that can withstand the growth temperature (~90°C and precursor solution chemicals. Results also revealed that there was a strong impact of growth time and ZnO seed layer deposition route on the orientation, density, diameter, and uniformity of the synthesized nanowires. A core-shell n-ZnO NWs/p-AgGaSe2 (AGS thin film solar cell was fabricated as a device application of synthesized ZnO nanowires by decoration of nanowires with ~700 nm thick sputtering deposited AGS thin film layer, which demonstrated an energy conversion efficiency of 1.74% under 100 mW/cm2 of simulated solar illumination.

  4. Structural and electronic properties of ZnO nanowires and nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Andreia Luisa da; Frauenheim, Thomas [BCCMS, Universitaet Bremen (Germany); Xu, Hu; Fan, Wei; Zhan, Fei; Zhang, Xiaohong [Nano-organic Photoelectronic Laboratory, Technical Institute of Physics and Chemistry, Beijing (China); Zhang, Ruiqin [COSDAF, Department of Physics and Materials Science, City University of Hong Kong SAR (China)

    2008-07-01

    ZnO is a well known semiconductor with potential applications in electronics and optoelectronics. ZnO has a direct wide band gap of 3.3 eV and a large exciton binding energy making it promising for high-efficiency blue and ultra-violet devices. Recently, the successful growth of highly ordered nanowires has expanded the list of potential applications. In this work we employ density functional theory to investigate ZnO nanowires and nanotubes. We find that relaxations on the facets are very similar to the ones in non-polar ZnO surfaces. While bare and completely passivated wires are semiconducting, wires with intermediate hydrogen passivation exhibit metallic behavior. We therefore suggest that hydrogenation leads to drastic changes in the ZnO nanowire electrical properties. We have also investigated ZnO nanotubes with round and hexagonal shapes. The calculated strain energy of round ZnO nanotubes follows a classical strain law. All the ZnO nanotubes were found to be direct band gap semiconductors with the band gap decreasing as their diameter increases.

  5. Enhanced photoconduction of free-standing ZnO nanowire films by L-lysine treatment

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jinzhang; Park, Jaeku; Ahn, Yeonghwan; Park, Ji-Yong; Koh, Ken Ha; Lee, Soonil [Division of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of); Park, Kyung Ho, E-mail: soonil@ajou.ac.kr [Korea Advanced Nano Fab Center, Suwon 443-270 (Korea, Republic of)

    2010-12-03

    Flexible paper-like ZnO nanowire films are fabricated and the effect of L-lysine passivation of the nanowire surfaces on improving the UV photoresponse is studied. We prepare three types of nanowires with different defect contents, and find that the L-lysine treatment can suppress the oxygen-vacancy-related photoluminescence as well as enhance the UV photoconduction. The nanowires with fewer defects gain larger enhancement of UV photoconduction after L-lysine treatment. Reproducible UV photoresponse of the devices in humid air is obtained due to L-lysine surface passivation, ruling out the influence of water molecules in degrading the UV photocurrent.

  6. Tuning of the electronic characteristics of ZnO nanowire field effect transistors by proton irradiation.

    Science.gov (United States)

    Hong, Woong-Ki; Jo, Gunho; Sohn, Jung Inn; Park, Woojin; Choe, Minhyeok; Wang, Gunuk; Kahng, Yung Ho; Welland, Mark E; Lee, Takhee

    2010-02-23

    We demonstrated a controllable tuning of the electronic characteristics of ZnO nanowire field effect transistors (FETs) using a high-energy proton beam. After a short proton irradiation time, the threshold voltage shifted to the negative gate bias direction with an increase in the electrical conductance, whereas the threshold voltage shifted to the positive gate bias direction with a decrease in the electrical conductance after a long proton irradiation time. The electrical characteristics of two different types of ZnO nanowires FET device structures in which the ZnO nanowires are placed on the substrate or suspended above the substrate and photoluminescence (PL) studies of the ZnO nanowires provide substantial evidence that the experimental observations result from the irradiation-induced charges in the bulk SiO(2) and at the SiO(2)/ZnO nanowire interface, which can be explained by a surface-band-bending model in terms of gate electric field modulation. Our study on the proton-irradiation-mediated functionalization can be potentially interesting not only for understanding the proton irradiation effects on nanoscale devices, but also for creating the property-tailored nanoscale devices.

  7. Selective growth and piezoelectric properties of highly ordered arrays of vertical ZnO nanowires on ultrathin alumina membranes

    Science.gov (United States)

    Wen, Liaoyong; Shao, Zhengzheng; Fang, Yaoguo; Wong, Kin Mun; Lei, Yong; Bian, Lifeng; Wilde, Gerhard

    2010-08-01

    A well controlled and cost effective method of fabricating highly ordered arrays of vertical zinc oxide (ZnO) nanowires or nanopores is demonstrated where an ultrathin alumina membrane (UTAM) itself is utilized as a substrate for the selective growth of the ordered arrays. A thin film of gold was thermally evaporated on the UTAM followed by the growth of highly regular ZnO nanowires using chemical vapor deposition (CVD). Alternatively, highly ordered ZnO nanopores arrays were also grown by CVD on the bare UTAM. Additionally, piezoelectric currents were generated from the ZnO nanowires during the conductive atomic force microscopy probe tip scan across the array.

  8. ZnO nanowires grown on carbon cloth for flexible cold cathode.

    Science.gov (United States)

    Tang, Haoying; Liu, Tengjiao; Jiang, Peng

    2013-02-01

    Nanostructures grown on carbon cloth are recently attracted great interests for flexible field emitter and cold cathode. In this paper, we report high-aspect ratio ZnO nanowires grown on carbon cloth by a low-temperature solution chemical approach that can be used as a flexible and high performance cold cathode. The carbon cloth is covered by outward-grown ZnO nanowires uniformly and densely with spiny structures. The hybrid structures exhibits a turn-on electrical field of 4.36 V/microm and a field enhancement factor of 1157, which benefit from the high-aspect ratios of both ZnO nanowires and carbon cloth. These results demonstrate a low cost and scalable approach for flexible cold cathode lighting and field emission display.

  9. Bandgap narrowing and ethanol sensing properties of In-doped ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Li, L M; Li, C C; Zhang, J; Du, Z F; Zou, B S; Yu, H C; Wang, Y G; Wang, T H [Micro-Nano Technologies Research Center, Hunan University, Changsha 410082 (China)

    2007-06-06

    Indium doping effects on the optical and electrical properties of ZnO nanowires are investigated. The abnormal Raman spectrum shows only a peak centred at 439 cm{sup -1} related to high E{sub 2} mode, which is due to In doping. The acceptor binding energy is estimated to be 93 meV from the results of temperature-dependent photoluminescence spectra. The redshift of the bandgap edge is attributed to a merging of donor and conduction bands. The sensitivity of the sensors fabricated from In-doped ZnO nanowires is about 3-1 ppm ethanol, and increases nearly linearly up to 27 as the ethanol concentration is raised to 100 ppm. Our results indicate that the In-doped ZnO nanowires have potential applications in fabricating optoelectrical devices and gas sensors.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-01

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

  11. Synthesis of high aspect ratio ZnO nanowires with an inexpensive handcrafted electrochemical setup

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, Ali, E-mail: at1361@aut.ac.ir, E-mail: atahery@aeoi.org.ir [Nuclear Science and Technology Institute (Iran, Islamic Republic of); Saramad, Shahyar; Setayeshi, Saeed [Amirkabir University of Technology, Faculty of Energy Engineering and Physics (Iran, Islamic Republic of)

    2016-12-15

    In this work, high aspect ratio zinc oxide nanowires are synthesized using templated one-step electrodeposition technique. Electrodeposition of the nanowires is done using a handcrafted electronic system. Nuclear track-etched polycarbonate membrane is used as a template to form the high aspect ratio nanowires. The result of X-ray diffraction and scanning electron microscopy shows that nanowires with a good crystallinity and an aspect ratio of more than 30 can be achieved in a suitable condition. The height of electrodeposited nanowires reaches to about 11 μm. Based on the obtained results, high aspect ratio ZnO nanowires can be formed using inexpensive electrodeposition setup with an acceptable quality.

  12. Single ZnO Nanowire-Based Gas Sensors to Detect Low Concentrations of Hydrogen

    Directory of Open Access Journals (Sweden)

    Marlene N. Cardoza-Contreras

    2015-12-01

    Full Text Available Low concentrations of hazardous gases are difficult to detect with common gas sensors. Using semiconductor nanostructures as a sensor element is an alternative. Single ZnO nanowire gas sensor devices were fabricated by manipulation and connection of a single nanowire into a four-electrode aluminum probe in situ in a dual-beam scanning electron microscope-focused ion beam with a manipulator and a gas injection system in/column. The electrical response of the manufactured devices shows response times up to 29 s for a 121 ppm of H2 pulse, with a variation in the nanowire resistance appreciable at room temperature and at 373.15 K of approximately 8% and 14% respectively, showing that ZnO nanowires are good candidates to detect low concentrations of H2.

  13. Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2Buffer Layers in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jiang Chunhua

    2009-01-01

    Full Text Available Abstract This paper reports the effects of the seed layers prepared by spin-coating and dip-coating methods on the morphology and density of ZnO nanowire arrays, thus on the performance of ZnO nanowire-based dye-sensitized solar cells (DSSCs. The nanowire films with the thick ZnO buffer layer (~0.8–1 μm thick can improve the open circuit voltage of the DSSCs through suppressing carrier recombination, however, and cause the decrease of dye loading absorbed on ZnO nanowires. In order to further investigate the effect of TiO2buffer layer on the performance of ZnO nanowire-based DSSCs, compared with the ZnO nanowire-based DSSCs without a compact TiO2buffer layer, the photovoltaic conversion efficiency and open circuit voltage of the ZnO DSSCs with the compact TiO2layer (~50 nm thick were improved by 3.9–12.5 and 2.4–41.7%, respectively. This can be attributed to the introduction of the compact TiO2layer prepared by sputtering method, which effectively suppressed carrier recombination occurring across both the film–electrolyte interface and the substrate–electrolyte interface.

  14. Electrical and optical behavior of ZnO nanowires irradiated by ion beam

    DEFF Research Database (Denmark)

    Lisevski, Caroline I.; Fernandes Cauduro, André Luis; Franzen, Paulo L

    2015-01-01

    Zinc oxide nanowires have been attracting much interest due to their potential use in electronics and optoelectonics devices. In this work, we report on the photoluminescence and electrical behavior of ZnO nanowires grown by vapor-liquid-solid method and irradiated with 1.2 MeV He+ ions at several...... doses. The results strongly indicates the existence of an enhanced dynamic annealing effect during the low fluence irradiations allowing it to heal low migration barrier point-defects such as oxygen interstitials (OI), zinc interstitials (ZnI), zinc antisites (ZnO) and oxygen antisites (OZn...

  15. Electrospun ZnO Nanowires as Gas Sensors for Ethanol Detection

    Directory of Open Access Journals (Sweden)

    Huang Po-Jung

    2009-01-01

    Full Text Available Abstract ZnO nanowires were produced using an electrospinning method and used in gas sensors for the detection of ethanol at 220 °C. This electrospinning technique allows the direct placement of ZnO nanowires during their synthesis to bridge the sensor electrodes. An excellent sensitivity of nearly 90% was obtained at a low ethanol concentration of 10 ppm, and the rest obtained at higher ethanol concentrations, up to 600 ppm, all equal to or greater than 90%.

  16. Engineering of the photoluminescence of ZnO nanowires by different growth and annealing environments

    DEFF Research Database (Denmark)

    Fernandes Cauduro, André Luis; Sombrio, C I L; Franzen, P L

    2015-01-01

    Optical properties of ZnO nanowires were investigated through photoluminescence (PL) at room and low temperatures. An excitonic structure was observed in the UV band emission and we are able to distinguish between free excitons, bound excitons and donor acceptor pairs. The PL spectra shows deep...... level emissions ranging from 1.4 eV up to 2.8 eV, strongly depending on surface defects whereas the red emission (1.7 eV) is activated at cryogenic temperatures. We attribute the green luminescence (2.4 eV) emission to the presence of zinc vacancies into ZnO nanowires. Further evidences that confirm...

  17. pH-Dependent Toxicity of High Aspect Ratio ZnO Nanowires in Macrophages Due to Intracellular Dissolution

    KAUST Repository

    H. Müller, Karin

    2010-11-23

    High-aspect ratio ZnO nanowires have become one of the most promising products in the nanosciences within the past few years with a multitude of applications at the interface of optics and electronics. The interaction of zinc with cells and organisms is complex, with both deficiency and excess causing severe effects. The emerging significance of zinc for many cellular processes makes it imperative to investigate the biological safety of ZnO nanowires in order to guarantee their safe economic exploitation. In this study, ZnO nanowires were found to be toxic to human monocyte macrophages (HMMs) at similar concentrations as ZnCl2. Confocal microscopy on live cells confirmed a rise in intracellular Zn2+ concentrations prior to cell death. In vitro, ZnO nanowires dissolved very rapidly in a simulated body fluid of lysosomal pH, whereas they were comparatively stable at extracellular pH. Bright-field transmission electron microscopy (TEM) showed a rapid macrophage uptake of ZnO nanowire aggregates by phagocytosis. Nanowire dissolution occurred within membrane-bound compartments, triggered by the acidic pH of the lysosomes. ZnO nanowire dissolution was confirmed by scanning electron microscopy/energy-dispersive X-ray spectrometry. Deposition of electron-dense material throughout the ZnO nanowire structures observed by TEM could indicate adsorption of cellular components onto the wires or localized zinc-induced protein precipitation. Our study demonstrates that ZnO nanowire toxicity in HMMs is due to pH-triggered, intracellular release of ionic Zn2+ rather than the high-aspect nature of the wires. Cell death had features of necrosis as well as apoptosis, with mitochondria displaying severe structural changes. The implications of these findings for the application of ZnO nanowires are discussed. © 2010 American Chemical Society.

  18. pH-dependent toxicity of high aspect ratio ZnO nanowires in macrophages due to intracellular dissolution.

    Science.gov (United States)

    Müller, Karin H; Kulkarni, Jaideep; Motskin, Michael; Goode, Angela; Winship, Peter; Skepper, Jeremy N; Ryan, Mary P; Porter, Alexandra E

    2010-11-23

    High-aspect ratio ZnO nanowires have become one of the most promising products in the nanosciences within the past few years with a multitude of applications at the interface of optics and electronics. The interaction of zinc with cells and organisms is complex, with both deficiency and excess causing severe effects. The emerging significance of zinc for many cellular processes makes it imperative to investigate the biological safety of ZnO nanowires in order to guarantee their safe economic exploitation. In this study, ZnO nanowires were found to be toxic to human monocyte macrophages (HMMs) at similar concentrations as ZnCl(2). Confocal microscopy on live cells confirmed a rise in intracellular Zn(2+) concentrations prior to cell death. In vitro, ZnO nanowires dissolved very rapidly in a simulated body fluid of lysosomal pH, whereas they were comparatively stable at extracellular pH. Bright-field transmission electron microscopy (TEM) showed a rapid macrophage uptake of ZnO nanowire aggregates by phagocytosis. Nanowire dissolution occurred within membrane-bound compartments, triggered by the acidic pH of the lysosomes. ZnO nanowire dissolution was confirmed by scanning electron microscopy/energy-dispersive X-ray spectrometry. Deposition of electron-dense material throughout the ZnO nanowire structures observed by TEM could indicate adsorption of cellular components onto the wires or localized zinc-induced protein precipitation. Our study demonstrates that ZnO nanowire toxicity in HMMs is due to pH-triggered, intracellular release of ionic Zn(2+) rather than the high-aspect nature of the wires. Cell death had features of necrosis as well as apoptosis, with mitochondria displaying severe structural changes. The implications of these findings for the application of ZnO nanowires are discussed.

  19. Power generation from base excitation of a Kevlar composite beam with ZnO nanowires

    Science.gov (United States)

    Malakooti, Mohammad H.; Hwang, Hyun-Sik; Sodano, Henry A.

    2015-04-01

    One-dimensional nanostructures such as nanowires, nanorods, and nanotubes with piezoelectric properties have gained interest in the fabrication of small scale power harvesting systems. However, the practical applications of the nanoscale materials in structures with true mechanical strengths have not yet been demonstrated. In this paper, piezoelectric ZnO nanowires are integrated into the fiber reinforced polymer composites serving as an active phase to convert the induced strain energy from ambient vibration into electrical energy. Arrays of ZnO nanowires are grown vertically aligned on aramid fibers through a low-cost hydrothermal process. The modified fabrics with ZnO nanowires whiskers are then placed between two carbon fabrics as the top and the bottom electrodes. Finally, vacuum resin transfer molding technique is utilized to fabricate these multiscale composites. The fabricated composites are subjected to a base excitation using a shaker to generate charge due to the direct piezoelectric effect of ZnO nanowires. Measuring the generated potential difference between the two electrodes showed the energy harvesting application of these multiscale composites in addition to their superior mechanical properties. These results propose a new generation of power harvesting systems with enhanced mechanical properties.

  20. Magnetic properties of ZnO nanowires with Li dopants and Zn vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Xinhong; Cai, Ningning [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, P.O. Box 72, Beijing 100876 (China); Yang, Chuanghua [School of Physics and Telecommunication Engineering, Shanxi University of Technology (SNUT), Hanzhong 723001, Shanxi (China); Chen, Jun [Beijing Applied Physics and Computational Mathematics, Beijing 100088 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, P.O. Box 72, Beijing 100876 (China)

    2016-04-30

    The electronic and magnetic properties of ZnO nanowire with Li dopants and vacancies have been investigated using first-principles density functional theory. It is found that the Zn vacancy can induce magnetism while increasing the formation energy of the system. However, the calculated results indicate that the introduction of Li-dopants will reduce the formation energy of system. We also have studied the magnetic couplings with vacancies as well as their corresponding configurations with Li-dopants for four configurations of ZnO nanowires. The results show that ferromagnetic properties can be improved/reversed after the introduction of Li-dopants. Ferromagnetic mechanism is originated from the fierce p–p hybridization of O near the Fermi level. We find that ferromagnetism of Li-doped ZnO nanowires with Zn vacancies can be realized at room temperature and they are promising spintronic materials. - Highlights: • Li-dopants will reduce the formation energy of ZnO nanowires with Zn vacancy. • The fierce p–p hybridization of O near Fermi level is responsible for FM properties. • Li-doped ZnO–V{sub Zn} nanowire is a promising FM semiconductor material.

  1. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts.

    Science.gov (United States)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-12-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 10(17)/m(3) orders of magnitude, which is practicable for most discharging applications.

  2. Quantum dots coupled ZnO nanowire-array panels and their photocatalytic activities.

    Science.gov (United States)

    Liao, Yulong; Que, Wenxiu; Zhang, Jin; Zhong, Peng; Yuan, Yuan; Qiu, Xinku; Shen, Fengyu

    2013-02-01

    Fabrication and characterization of a heterojunction structured by CdS quantum dots@ZnO nanowire-array panels were presented. Firstly, ZnO nanowire-array panels were prepared by using a chemical bath deposition approach where wurtzite ZnO nanowires with a diameter of about 100 nm and 3 microm in length grew perpendicularly to glass substrate. Secondly, CdS quantum dots were deposited onto the surface of the ZnO nanowire-arrays by using successive ion layer absorption and reaction method, and the CdS shell/ZnO core heterojunction were thus obtained. Field emission scanning electron microscopy and transmission electron microscope were employed to characterize the morphological properties of the as-obtained CdS quantum dots@ZnO nanowire-array panels. X-ray diffraction was adopted to characterize the crystalline properties of the as-obtained CdS quantum dots@ZnO nanowire-array panels. Methyl orange was taken as a model compound to confirm the photocatalytic activities of the CdS shell/ZnO core heterojunction. Results indicate that CdS with narrow band gap not only acts as a visible-light sensitizer but also is responsible for an effective charge separation.

  3. Chemical bath deposition of ZnO nanowires at near-neutral pH conditions without hexamethylenetetramine (HMTA): understanding the role of HMTA in ZnO nanowire growth.

    Science.gov (United States)

    McPeak, Kevin M; Le, Thinh P; Britton, Nathan G; Nickolov, Zhorro S; Elabd, Yossef A; Baxter, Jason B

    2011-04-05

    Chemical bath deposition (CBD) is an inexpensive and reproducible method for depositing ZnO nanowire arrays over large areas. The aqueous Zn(NO(3))(2)-hexamethylenetetramine (HMTA) chemistry is one of the most common CBD chemistries for ZnO nanowire synthesis, but some details of the reaction mechanism are still not well-understood. Here, we report the use of in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to study HMTA adsorption from aqueous solutions onto ZnO nanoparticle films and show that HMTA does not adsorb on ZnO. This result refutes earlier claims that the anisotropic morphology arises from HMTA adsorbing onto and capping the ZnO {10 1 0} faces. We conclude that the role of HMTA in the CBD of ZnO nanowires is only to control the saturation index of ZnO. Furthermore, we demonstrate the first deposition of ZnO nanowire arrays at 90 °C and near-neutral pH conditions without HMTA. Nanowires were grown using the pH buffer 2-(N-morpholino)ethanesulfonic acid (MES) and continuous titratation with KOH to maintain the same pH conditions where growth with HMTA occurs. This semi-batch synthetic method opens many new opportunities to tailor the ZnO morphology and properties by independently controlling temperature and pH.

  4. Growth behavior and field emission property of ZnO nanowire arrays on Au and Ag films

    Directory of Open Access Journals (Sweden)

    Sung Hyun Kim

    2013-09-01

    Full Text Available We propose a facile method to control the growth and areal density of zinc-oxide (ZnO nanowire arrays using gold or silver films deposited on aluminum-doped ZnO (AZO layers coated on glass substrates. Nanowires exceeding 5 μm in length grew on both the glass/AZO-layer and on the glass/AZO-layer/Au-film where the areal array density was controlled primarily by changing the annealing temperature. In contrast, the nanowire arrays grew only on the AZO surface but not on the Ag film owing to the formation of an Ag-oxide layer. We fabricated field emitter devices with density controlled ZnO nanowire arrays and low turn-on electric field of ∼6 V/μm and a field enhancement factor of up to 1188 were obtained with density controlled ZnO nanowire arrays.

  5. Effect of gamma radiation on the optical and structural properties of ZnO nanowires with various diameters

    Science.gov (United States)

    Reyhani, A.; Gholizadeh, A.; vahedi, V.; Khanlari, M. R.

    2018-01-01

    The effects of gamma-irradiation are studied on the morphology and structural properties of ZnO nanowire with various diameters. The ZnO nanowires are grown using Zn thin films at various initial thicknesses including 125, 250 and 500 nm in air ambient. The results illustrate dramatic effects of Gamma-irradiation on the deformation of ZnO nanowires. Thus, radiation induce ripple ZnO surfaces instead ZnO nanowires. Gamma-irradiation has also been effective on the optical and crystalline properties of the nanowires. X-ray diffraction attests that size of the ZnO nano-structures has changed and (l00) crystalline direction related to Zn metal has been created after irradiation. UV-Visible spectra display two areas for transmittance of irradiated ZnO nanowires, one in the Visible-light and the other in IR sub-region. In the Visible-light area, the layer gets thicker from 125 to 500 nm; the difference between the layer transmittance spectra is reduced before and after gamma irradiation. In the IR-light region, with increasing of ZnO initial thickness, the difference between the layer transmittance spectra is increased before and after gamma irradiation. The photoluminescence spectroscopy displays that intensity of green-yellow band improves in compared to near-band-edge emission due to formation of Zn metal and oxygen vacancies after gamma irradiation.

  6. Spatial mapping of exciton lifetimes in single ZnO nanowires

    Directory of Open Access Journals (Sweden)

    J. S. Reparaz

    2013-07-01

    Full Text Available We investigate the spatial dependence of the exciton lifetimes in single ZnO nanowires. We have found that the free exciton and bound exciton lifetimes exhibit a maximum at the center of nanowires, while they decrease by 30% towards the tips. This dependence is explained by considering the cavity-like properties of the nanowires in combination with the Purcell effect. We show that the lifetime of the bound-excitons scales with the localization energy to the power of 3/2, which validates the model of Rashba and Gurgenishvili at the nanoscale.

  7. Mechanical transfer of ZnO nanowires for a flexible and conformal piezotronic strain sensor

    Science.gov (United States)

    Jenkins, Kory; Yang, Rusen

    2017-07-01

    We demonstrate a truly conformal and flexible piezotronic strain sensor using zinc oxide (ZnO) nanowires. Well-aligned, vertical ZnO nanowires are grown by chemical vapor deposition on a silicon wafer with a hydrothermally grown ZnO seed layer. The nanowires are infiltrated with polydimethylsiloxane and mechanically transferred from the silicon substrate. Plasma etching exposes the top surface of the nanowires before deposition of a gold (Au) top electrode. The bottom electrode is formed by silver paint which also adheres the sensor to the measured structure. To demonstrate the sensor’s ability to conform to complex surfaces, a stepped shaft with a shoulder fillet is used. The sensor is attached to the shoulder fillet of the stepped shaft, conforming to both the circumference of the shaft, and the radius of the fillet. A periodic bending displacement is applied to the end of the shaft. The strain induces a piezoelectric potential in the ZnO nanowires which controls the barrier height and conductivity at the gold/ZnO interface, by what is known as the piezotronic effect. The conductivity change is measured for periodically applied strains. The nonlinear current-voltage (I-V) response of the device is due to the Schottky contact between the ZnO nanowires and gold electrode. The geometry of the stepped shaft corresponds to a known stress concentration factor, and the strain experienced by the shaft is estimated with a COMSOL FEA study. The conformal nature of the strain sensor makes it suitable for structural monitoring applications involving complex geometries and stress concentrators.

  8. Growth of ZnO nanowires on polypropylene membrane surface—Characterization and reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Bojarska, Marta, E-mail: m.bojarska@ichip.pw.edu.pl [Warsaw University of Technology, Faculty of Chemical and Process Engineering, Waryńskiego 1, 00-645 Warsaw (Poland); Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, Essen 45117 (Germany); Nowak, Bartosz, E-mail: novakbartosz@gmail.com [Warsaw University of Technology, Faculty of Chemical and Process Engineering, Waryńskiego 1, 00-645 Warsaw (Poland); Skowroński, Jarosław, E-mail: jaroslaw.skowronski@itee.radom.pl [Institute for Sustainable Technologies—National Research Institute, Pułaskiego 6/10, 26-600 Radom (Poland); Piątkiewicz, Wojciech, E-mail: w.piatkiewicz@polymemtech.com [Institute for Sustainable Technologies—National Research Institute, Pułaskiego 6/10, 26-600 Radom (Poland); PolymemTech Sp. z o.o., al. Niepodległości 118/90, 02-577 Warsaw (Poland); Gradoń, Leon, E-mail: l.gradon@ichip.pw.edu.pl [Warsaw University of Technology, Faculty of Chemical and Process Engineering, Waryńskiego 1, 00-645 Warsaw (Poland)

    2017-01-01

    Highlights: • ZnO nanowires were grown on a polypropylene microfiltration capillary membrane. • Plasma treatment was used for membrane activation and hydrophilization. • The photocatalytic/antibacterial properties were studied upon light irradiation. • PP/ZnO nanowires membrane show good photocatalytic and antibacterial activity. • We report a new method for obtaining reactive membranes with ZnO nanowires. - Abstract: Need for a new membrane is clearly visible in recent studies, mostly due to the fouling phenomenon. Authors, focused on problem of biofouling caused by microorganisms that are present in water environment. An attempt to form a new membrane with zinc oxide (ZnO) nanowires was made; where plasma treatment was used as a first step of modification followed by chemical bath deposition. Such membrane will exhibit additional reactive properties. ZnO, because of its antibacterial and photocatalytic properties, is more and more often used in commercial applications. The authors used SEM imaging, measurement of the contact angle, XRD and the FT–IR analysis for membrane characterization. Amount of ZnO deposited on membrane surface was also investigated by dithizone method. Photocatalytic properties of such membranes were examined through methylene blue and humic acid degradation in laboratory scale modules with LEDs as either: wide range white or UV light source. Antibacterial and antifouling properties of polypropylene membranes modified with ZnO nanowires were examined through a series of tests involving microorganisms: model gram-positive and −negative bacteria. The obtained results showed that it is possible to modify the membrane surface in such a way, that additional reactive properties will be given. Thus, not only did the membrane become a physical barrier, but also turned out to be a reactive one.

  9. Screw dislocation-driven epitaxial solution growth of ZnO nanowires seeded by dislocations in GaN substrates.

    Science.gov (United States)

    Morin, Stephen A; Jin, Song

    2010-09-08

    In the current examples of dislocation-driven nanowire growth, the screw dislocations that propagate one-dimensional growth originate from spontaneously formed highly defective "seed" crystals. Here we intentionally utilize screw dislocations from defect-rich gallium nitride (GaN) thin films to propagate dislocation-driven growth, demonstrating epitaxial growth of zinc oxide (ZnO) nanowires directly from aqueous solution. Atomic force microscopy confirms screw dislocations are present on the native GaN surface and ZnO nanowires grow directly from dislocation etch pits of heavily etched GaN surfaces. Furthermore, transmission electron microscopy confirms the existence of axial dislocations. Eshelby twist in the resulting ZnO nanowires was confirmed using bright-/dark-field imaging and twist contour analysis. These results further confirm the connection between dislocation source and nanowire growth. This may eventually lead to defect engineering strategies for rationally designed catalyst-free dislocation-driven nanowire growth for specific applications.

  10. Measurement of light diffusion in ZnO nanowire forests

    NARCIS (Netherlands)

    Versteegh, M.A.M.; van der Wel, R.E.C.; Dijkhuis, J.I.

    2012-01-01

    Optimum design of efficient nanowire solar cells requires better understanding of light diffusion in a nanowire array. Here we demonstrate that our recently developed ultrafast all-optical shutter can be used to directly measure the dwell time of light in a nanowire array. Our measurements on

  11. Hydrothermal growth of ZnO nanowires on flexible fabric substrates

    Science.gov (United States)

    Hong, Gwang-Wook; Yun, Sang-Ho; Kim, Joo-Hyung

    2016-04-01

    ZnO nanowires (NWs) would provide significant enhancement in sensitivity due to high surface to volume ratio. We investigated the first methodical study on the quantitative relationship between the process parameters of solution concentration ratio, structure, and physical and properties of ZnO NWs grown on different flexible fabric surfaces. To develop a fundamental following concerning various substrates, we controlled the growth speed of ZnO NWs and nanowires on cotton surface with easy and moderate cost fabrication method. Using ammonium hydroxide as the reactant with zinc nitrate hexahydrate, ZnO NWs layer have been grown on metal layers, instead of seed layer. ZnO NWs fabrication was done on different fabric substrates such as wool, nylon and polypropylene (PP). After the ZnO NWs grown to each substrates, we coated insulating layer with polyurethane (PU) and ethyl cellulose for prevent external intervention. Detailed electrical characterization was subsequently performed to reveal the working characteristics of the hybrid fabric. For electrical verification of fabricated ZnO NWs, we implemented measurement impact test and material properties with FFT analyzer and LCR meter.

  12. Manipulating the quantum interference effect and magnetotransport of ZnO nanowires through interfacial doping.

    Science.gov (United States)

    Zhao, Siwen; Wu, Yiming; Zhang, Kaixuan; Ding, Huaiyi; Du, Dongxue; Zhao, Jiyin; Pan, Nan; Wang, Xiaoping

    2017-11-16

    We carefully prepared interfacial Al-doped (IAD) and interfacial natively-doped (IND) ZnO nanowires (NWs) by introducing atomic-layer interfacial Δ-doping between the two steps of CVD growth. Variable-temperature electron transport as well as magnetotransport behaviours of these NWs were systematically investigated. By virtue of the unique architecture and the quality-guaranteed growth technique, a series of quantum interference effects were clearly observed in the IAD ZnO NWs, including weak localization, universal conductance fluctuation and Altshuler-Aronov-Spivak oscillations. The phase-coherence length (L φ ) of electrons exceeds 100 nm in the IAD ZnO NWs, much longer than those in the IND ones and most conventionally doped ZnO NWs. This ability to efficiently manipulate a variety of quantum interference effects in ZnO NWs is very desirable for applications in nano-optoelectronics, nano- & quantum-electronics and solid-state quantum computing.

  13. Synthesis of ordered ZnO nanowire arrays from aqueous solution using AAO template

    Science.gov (United States)

    Kumar, Nagesh; Varma, G. D.; Nath, R.; Srivastava, A. K.

    2011-09-01

    In this paper we report a simple method that enables the easy fabrication of ordered ZnO nanowire arrays using Anodic Aluminium Oxide (AAO) template. We have used a vacuum injection technique to fill solution into the pores of an AAO template. The AAO template has been fabricated by a two-step anodization process using 0.3 M oxalic acid (H2C2O4) solution under a constant voltage of 40 V. The AAO template formed through this process has been detached from Al substrate via an anodic voltage pulse using perchloric acid (HClO4) solution (70%). The nanowires of ZnO have been synthesized by injecting the saturated Zn(NO3)2 solution into the pores of the detached AAO template using a vacuum pump. The ZnO nanowires synthesized by this technique have been found dense & continuous with uniform diameter throughout the length of the wire. The structural characteristics of AAO template and ZnO nanowires have been studied by Field Emission Scanning Electron Microscope (FESEM), Atomic force microscope (AFM) and Transmission Electron Microscope (TEM).

  14. Enhanced Response Speed of ZnO Nanowire Photodetector by Coating with Photoresist

    Directory of Open Access Journals (Sweden)

    Xing Yang

    2016-01-01

    Full Text Available Spin-coating photoresist film on ZnO nanowire (NW was introduced into the fabrication procedure to improve photoresponse and recovery speed of a ZnO NW ultraviolet photoelectric detector. A ZnO NW was first assembled on prefabricated electrodes by dielectrophoresis. Then, photoresist was spin-coated on the nanowire. Finally, a metal layer was electrodeposited on the nanowire-electrode contacts. The response properties and I-V characteristics of ZnO NW photodetector were investigated by measuring the electrical current under different conditions. Measurement results demonstrated that the detector has an enhanced photoresponse and recovery speed after coating the nanowire with photoresist. The photoresponse and recovery characteristics of detectors with and without spin-coating were compared to demonstrate the effects of photoresist and the enhancement of response and recovery speed of the photodetector is ascribed to the reduced surface absorbed oxygen molecules and binding effect on the residual oxygen molecules after photoresist spin-coating. The results demonstrated that surface coating may be an effective and simple way to improve the response speed of the photoelectric device.

  15. Conductivity of ZnO nanowires, nanoparticles, and thin films using time-resolved terahertz spectroscopy.

    Science.gov (United States)

    Baxter, Jason B; Schmuttenmaer, Charles A

    2006-12-21

    The terahertz absorption coefficient, index of refraction, and conductivity of nanostructured ZnO have been determined using time-resolved terahertz spectroscopy, a noncontact optical probe. ZnO properties were measured directly for thin films and were extracted from measurements of nanowire arrays and mesoporous nanoparticle films by applying Bruggeman effective medium theory to the composite samples. Annealing significantly reduces the intrinsic carrier concentration in the ZnO films and nanowires, which were grown by chemical bath deposition. The complex-valued, frequency-dependent photoconductivities for all morphologies were found to be similar at short pump-probe delay times. Fits using the Drude-Smith model show that films have the highest mobility, followed by nanowires and then nanoparticles, and that annealing the ZnO increases its mobility. Time constants for decay of photoinjected electron density in films are twice as long as those in nanowires and more than 5 times those for nanoparticles due to increased electron interaction with interfaces and grain boundaries in the smaller-grained materials. Implications for electron transport in dye-sensitized solar cells are discussed.

  16. Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huawei [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Cong, Zixiang [School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100976 (China); Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2013-12-02

    Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material.

  17. Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin, E-mail: lin.wang@insa-lyon.fr; Brémond, Georges [Institut des Nanotechnologies de Lyon (INL), Université de Lyon, CNRS UMR 5270, INSA Lyon, Bat. Blaise Pascal, 7 Avenue, Jean Capelle, 69621 Villeurbanne (France); Sallet, Vincent; Sartel, Corinne [Groupe d' étude de la Matière Condensée (GEMaC), CNRS - Université de Versailles St Quentin en Yvelines, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035 Versailles (France)

    2016-08-29

    ZnO/ZnO:Sb core-shell structured nanowires (NWs) were grown by the metal organic chemical vapor deposition method where the shell was doped with antimony (Sb) in an attempt to achieve ZnO p-type conduction. To directly investigate the Sb doping effect in ZnO, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were performed on the NWs' cross-sections mapping their two dimensional (2D) local electrical properties. Although no direct p-type inversion in ZnO was revealed, a lower net electron concentration was pointed out for the Sb-doped ZnO shell layer with respect to the non-intentionally doped ZnO core, indicating an evident compensating effect as a result of the Sb incorporation, which can be ascribed to the formation of Sb-related acceptors. The results demonstrate SCM/SSRM investigation being a direct and effective approach for characterizing radial semiconductor one-dimensional (1D) structures and, particularly, for the doping study on the ZnO nanomaterial towards its p-type realization.

  18. Development of multifunctional fiber reinforced polymer composites through ZnO nanowire arrays

    Science.gov (United States)

    Malakooti, Mohammad H.; Patterson, Brendan A.; Hwang, Hyun-Sik; Sodano, Henry A.

    2016-04-01

    Piezoelectric nanowires, in particular zinc oxide (ZnO) nanowires, have been vastly used in the fabrication of electromechanical devices to convert wasted mechanical energy into useful electrical energy. Over recent years, the growth of vertically aligned ZnO nanowires on various structural fibers has led to the development of fiber-based nanostructured energy harvesting devices. However, the development of more realistic energy harvesters that are capable of continuous power generation requires a sufficient mechanical strength to withstand typical structural loading conditions. Yet, a durable, multifunctional material system has not been developed thoroughly enough to generate electrical power without deteriorating the mechanical performance. Here, a hybrid composite energy harvester is fabricated in a hierarchical design that provides both efficient power generating capabilities while enhancing the structural properties of the fiber reinforced polymer composite. Through a simple and low-cost process, a modified aramid fabric with vertically aligned ZnO nanowires grown on the fiber surface is embedded between woven carbon fabrics, which serve as the structural reinforcement as well as the top and the bottom electrodes of the nanowire arrays. The performance of the developed multifunctional composite is characterized through direct vibration excitation and tensile strength examination.

  19. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    KAUST Repository

    Aravindh, S. Assa

    2014-12-19

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48O48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high TC in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  20. Fabrication and Characterization of ZnO Nanowire Arrays with an Investigation into Electrochemical Sensing Capabilities

    Directory of Open Access Journals (Sweden)

    Jessica Weber

    2008-01-01

    Full Text Available ZnO nanowire arrays were grown on a Si (100 substrate using the vapor-liquid-solid (VLS method. ZnO nanowires were characterized by XRD, SEM, bright field TEM, and EDS. They were found to have a preferential orientation along the c-axis. The as-prepared sample was functionalized with glucose oxidase by physical adsorption. FTIR was taken before and after functionalization to verify the presence of the attached enzyme. Electrochemical measurements were performed on the nanowire array by differential pulse voltammetry in the range of −0.6 to 0.4 V. The nanoarray sensor displayed high sensitivity to glucose in the range of 1.0 ×10−4 to 1.0 ×10−2 mol L−1.

  1. Morphology-dependent field emission properties and wetting behavior of ZnO nanowire arrays

    Directory of Open Access Journals (Sweden)

    Ma Li

    2011-01-01

    Full Text Available Abstract The fabrication of three kinds of ZnO nanowire arrays with different structural parameters over Au-coated silicon (100 by facile thermal evaporation of ZnS precursor is reported, and the growth mechanism are proposed based on structural analysis. Field emission (FE properties and wetting behavior were revealed to be strongly morphology dependent. The nanowire arrays in small diameter and high aspect ratio exhibited the best FE performance showing a low turn-on field (4.1 V/μm and a high field-enhancement factor (1745.8. The result also confirmed that keeping large air within the films was an effective way to obtain super water-repellent properties. This study indicates that the preparation of ZnO nanowire arrays in an optimum structural model is crucial to FE efficiency and wetting behavior.

  2. ZnO nanowires: Synthesis and charge transfer mechanism in the detection of ammonia vapour

    Science.gov (United States)

    Nancy Anna Anasthasiya, A.; Ramya, S.; Rai, P. K.; Jeyaprakash, B. G.

    2018-01-01

    ZnO nanowires with hexagonal wurtzite structure were grown on the glass substrate using Successive Ionic Layer Adsorption and Reaction (SILAR) method. Both experimental and theoretical studies demonstrated that NH3 chemisorbed and transferred the charge to the surface of the nanowire via its nitrogen site to the zinc site of ZnO nanowires, leading to the detection of NH3 vapour. The adsorbed ammonia dissociated into NH2 and H due to steric repulsion, and then into N2 and H2 gas. The formation of the N2 gas during the desorption process confirmed by observing peak at 14 and 28 m/z in the GC-MS spectrum.

  3. Synthesis and red-shifted photoluminescence of single-crystalline ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yuan [School of Chemistry and Environment, BeiHang University, Beijing 100083 (China)], E-mail: dengyuan@buaa.edu.cn; Wang Guangsheng; Li Na [School of Chemistry and Environment, BeiHang University, Beijing 100083 (China); Guo Lin [School of Chemistry and Environment, BeiHang University, Beijing 100083 (China)], E-mail: guolin@buaa.edu.cn

    2009-01-15

    Local-oriented single-crystalline ZnO nanowires have been synthesized in large scale by a simple microemulsion method in the presence of sulfonate-polystyrene (S-PS) and dodecyl benzene sulfonic acid sodium salt (DBS). The as-prepared product is characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), infrared (IR) spectra and photoluminescence (PL) spectrum. The nanowires exhibit a local congregation and preferentially grow along the [0 0 2] facet. FT-IR spectrum indicates that S-PS is adsorbed on the surface of ZnO nanowires. The PL spectrum shows evidently red-shifted ultraviolet (UV) emission.

  4. Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique

    Directory of Open Access Journals (Sweden)

    Oye Michael

    2011-01-01

    Full Text Available Abstract ZnO nanowire nucleation mechanism and initial stages of nanowire growth using the carbothermal reduction technique are studied confirming the involvement of the catalyst at the tip in the growth process. Role of the Au catalyst is further confirmed when the tapering observed in the nanowires can be explained by the change in the shape of the catalyst causing a variation of the contact area at the liquid–solid interface of the nanowires. The rate of decrease in nanowire diameter with length on the average is found to be 0.36 nm/s and this rate is larger near the base. Variation in the ZnO nanowire diameter with length is further explained on the basis of the rate at which Zn atoms are supplied as well as the droplet stability at the high flow rates and temperature. Further, saw-tooth faceting is noticed in tapered nanowires, and the formation is analyzed crystallographically.

  5. A Grazing-Incidence Small-Angle X-Ray Scattering View of Vertically Aligned ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    M. Lučić Lavčević

    2013-01-01

    Full Text Available We report a grazing-incidence small-angle X-ray scattering study of ZnO films with vertically aligned and randomly distributed nanowires, grown through a hydrothermal growth process on nanostructured ZnO seeding coatings and deposited by electron beam evaporation on silicon and glass, respectively. The comparison of the scattering patterns of seeding coatings and nanowires showed that the scattering of vertically aligned nanowires exhibited a specific feature: the dominant characteristic of their scattering patterns is the appearance of fine structure effects around the specular peak. These effects were clarified by the combined reflection and scattering phenomena, suggested for the aligned nanowires-substrate system. Furthermore, they enabled the calculation of the average gyration radius of nanowires in horizontal direction. The calculated value was in good agreement with the radii of nanowires estimated by surface electron microscopy. Therefore, the observed feature in the scattering pattern can serve as evidence of the aligned growth of nanowires.

  6. Fabrication of ZnO and ZnO:Sb Nanoparticles for Gas Sensor Applications

    OpenAIRE

    Kashyout, A.B.; Soliman,H. M. A.; H. Shokry Hassan; Abousehly, A. M.

    2010-01-01

    ZnO and Sb-doped ZnO nanoparticles were successfully prepared using sol-gel technique. Different concentrations of triethanolamine (TEA) were utilized as the preparation procedure to act as complexing agent that enhances the doping probability of the formed Sb-doped ZnO nanopowder. Thick films of the prepared nanopowders were fabricated with spinner coating. Morphological characteristics, phase structure, chemical composition, thermal stability, and optical properties of the prepared nanopowd...

  7. Influence of ZnO nanowire array morphology on field emission characteristics.

    Science.gov (United States)

    Garry, S; McCarthy, É; Mosnier, J-P; McGlynn, E

    2014-04-04

    In this work the growth and field emission properties of vertically aligned and spatially ordered and unordered ZnO nanowires are studied. Spatially ordered nanowire arrays of controlled array density are synthesized by both chemical bath deposition and vapour phase transport using an inverse nanosphere lithography technique, while spatially unordered arrays are synthesized by vapour phase transport without lithography. The field emission characteristics of arrays with 0.5, 1.0, and 1.5 μm inter-wire distances, as well as unordered arrays, are examined, revealing that, within the range of values examined, field emission properties are mainly determined by variations in nanowire height, and show no correlation with nanowire array density. Related to this, we find that a significant variation in nanowire height in an array also leads to a reduction in catastrophic damage observed on samples during field emission because arrays with highly uniform heights are found to suffer significant arcing damage. We discuss these results in light of recent computational studies of comparable nanostructure arrays and find strong qualitative agreement between our results and the computational predictions. Hence the results presented in this work should be useful in informing the design of ZnO nanowire arrays in order to optimize their field emission characteristics generally.

  8. Functionalized ZnO nanowires for microcantilever biosensors with enhanced binding capability.

    Science.gov (United States)

    Stassi, Stefano; Chiadò, Alessandro; Cauda, Valentina; Palmara, Gianluca; Canavese, Giancarlo; Laurenti, Marco; Ricciardi, Carlo

    2017-04-01

    An efficient way to increase the binding capability of microcantilever biosensors is here demonstrated by growing zinc oxide nanowires (ZnO NWs) on their active surface. A comprehensive evaluation of the chemical compatibility of ZnO NWs brought to the definition of an innovative functionalization method able to guarantee the proper immobilization of biomolecules on the nanostructured surface. A noteworthy higher amount of grafted molecules was evidenced with colorimetric assays on ZnO NWs-coated devices, in comparison with functionalized and activated silicon flat samples. ZnO NWs grown on silicon microcantilever arrays and activated with the proposed immobilization strategy enhanced the sensor binding capability (and thus the dynamic range) of nearly 1 order of magnitude, with respect to the commonly employed flat functionalized silicon devices. Graphical Abstract An efficient way to increase the binding capability of microcantilever biosensors is represented by growing zinc oxide nanowires (ZnO NWs) on their active surface. ZnO NWs grown on silicon microcantilever arrays and activated with an innovative immobilization strategy enhanced the sensor binding capability of nearly 1 order of magnitude, with respect to the commonly employed flat functionalized silicon devices.

  9. Title: Using Alignment and 2D Network Simulations to Study Charge Transport Through Doped ZnO Nanowire Thin Film Electrodes

    KAUST Repository

    Phadke, Sujay

    2011-09-30

    Factors affecting charge transport through ZnO nanowire mat films were studied by aligning ZnO nanowires on substrates and coupling experimental measurements with 2D nanowire network simulations. Gallium doped ZnO nanowires were aligned on thermally oxidized silicon wafer by shearing a nanowire dispersion in ethanol. Sheet resistances of nanowire thin films that had current flowing parallel to nanowire alignment direction were compared to thin films that had current flowing perpendicular to nanowire alignment direction. Perpendicular devices showed ∼5 fold greater sheet resistance than parallel devices supporting the hypothesis that aligning nanowires would increase conductivity of ZnO nanowire electrodes. 2-D nanowire network simulations of thin films showed that the device sheet resistance was dominated by inter-wire contact resistance. For a given resistivity of ZnO nanowires, the thin film electrodes would have the lowest possible sheet resistance if the inter-wire contact resistance was one order of magnitude lower than the single nanowire resistance. Simulations suggest that the conductivity of such thin film devices could be further enhanced by using longer nanowires. Solution processed Gallium doped ZnO nanowires are aligned on substrates using an innovative shear coating technique. Nanowire alignment has shown improvement in ZnO nanowire transparent electrode conductivity. 2D network simulations in conjunction with electrical measurements have revealed different regimes of operation of nanowire thin films and provided a guideline for improving electrical performance of nanowire electrodes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. ZnO nanowires array grown on Ga-doped ZnO single crystal for dye-sensitized solar cells.

    Science.gov (United States)

    Hu, Qichang; Li, Yafeng; Huang, Feng; Zhang, Zhaojun; Ding, Kai; Wei, Mingdeng; Lin, Zhang

    2015-06-23

    High quality ZnO nanowires arrays were homoepitaxial grown on Ga-doped ZnO single crystal (GZOSC), which have the advantages of high conductivity, high carrier mobility and high thermal stability. When it was employed as a photoanode in the DSSCs, the cell exhibited a 1.44% power-conversion efficiency under the illumination of one sun (AM 1.5G). The performance is superior to our ZnO nanowires/FTO based DSSCs under the same condition. This enhanced performance is mainly attributed to the perfect interface between the ZnO nanowires and the GZOSC substrate that contributes to lower carrier scattering and recombination rates compared with that grown on traditional FTO substrate.

  11. Opto-mechano-electrical tripling in ZnO nanowires probed by photocurrent spectroscopy in a high-resolution transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.; Golberg, D., E-mail: xuzhi@iphy.ac.cn, E-mail: golberg.dmitri@nims.go.jp [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 3050044 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennodai 1, Tsukuba, Ibaraki 3058577 (Japan); Xu, Z., E-mail: xuzhi@iphy.ac.cn, E-mail: golberg.dmitri@nims.go.jp [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Kvashnin, D. G. [National University of Science and Technology, MISIS, Leninskiy Prospect 4, Moscow 119049 (Russian Federation); Tang, D.-M.; Xue, Y. M.; Bando, Y. [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 3050044 (Japan); Sorokin, P. B. [National University of Science and Technology, MISIS, Leninskiy Prospect 4, Moscow 119049 (Russian Federation); Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny 141700 (Russian Federation)

    2015-08-31

    Photocurrent spectroscopy of individual free-standing ZnO nanowires inside a high-resolution transmission electron microscope (TEM) is reported. By using specially designed optical in situ TEM system capable of scanning tunneling microscopy probing paired with light illumination, opto-mechano-electrical tripling phenomenon in ZnO nanowires is demonstrated. Splitting of photocurrent spectra at around 3.3 eV under in situ TEM bending of ZnO nanowires directly corresponds to nanowire deformation and appearance of expanded and compressed nanowire sides. Theoretical simulation of a bent ZnO nanowire has an excellent agreement with the experimental data. The splitting effect could be explained by a change in the valence band structure of ZnO nanowires due to a lattice strain. The strain-induced splitting provides important clues for future flexible piezo-phototronics.

  12. Nanoparticulate PdZn as a Novel Catalyst for ZnO Nanowire Growth

    Directory of Open Access Journals (Sweden)

    Rachamim Aron

    2010-01-01

    Full Text Available Abstract ZnO nanowires have been grown by chemical vapour deposition (CVD using PdZn bimetallic nanoparticles to catalyse the process. Nanocatalyst particles with mean particle diameters of 2.6 ± 0.3 nm were shown to catalyse the growth process, displaying activities that compare well with those reported for sputtered systems. Since nanowire diameters are linked to catalyst morphology, the size-control we are able to exhibit during particle preparation represents an advantage over existing approaches in terms of controlling nanowire dimensions, which is necessary in order to utilize the nanowires for catalytic or electrical applications. (See supplementary material 1 Electronic supplementary material The online version of this article (doi:10.1007/s11671-010-9567-4 contains supplementary material, which is available to authorized users. Click here for file

  13. ZnO Hemisphere Pits Nanowire/CdS Photoelectrode for High-Efficiency Photoelectrochemical Water Splitting

    Science.gov (United States)

    Chen, Peiyang; Liu, Zhifeng; Geng, Xuemin; Wang, Jialu; Zhang, Min; Liu, Junqi; Yan, Lu

    2017-03-01

    In this paper, a ZnO hemisphere pits nanowire (HPW) photoelectrode is fabricated by using polystyrene (PS) nanospheres as templates, and CdS is deposited on ZnO nanowires to improve further its photoelectrochemical performance. Firstly, PS nanospheres are deposited on ZnO seed layers by air-liquid interface self-assembling method. Subsequently, ZnO HPWs are grown which effected by PS nanospheres. Finally, CdS nanoparticles were deposited on the ZnO HPWs to construct ZnO/CdS heterojunction photoanodes by successive ionic layer adsorption and reaction method. This hemisphere pits nanowires composite structure demonstrated a highly efficient photoelectrocatalytic performance with a remarkable photocurrent density of 2.27 mA cm-2 determined at 0.8 V versus Ag/AgCl. The enhanced performance of ZnO hemisphere pits nanowires/CdS nanoparticles (ZnO/CdS) composite photoanodes originated from the enhanced light absorption in the visible region and reduced photogenerated charges recombination rate. Furthermore, compared with ordinary nanowire arrays, hemisphere pits nanowire structure can reflect light more times to facilitate light harvesting. This work exhibits the important significance in constructing photoelectrodes for photoelectrochemical water splitting and other photoelectric devices.

  14. In-situ observation of hydrothermal growth of ZnO nanowires on patterned Zn substrate and their photocatalytic performance

    Science.gov (United States)

    Liu, Xinmei; Huang, Wenyi; Cheng, Hao; Huang, Bangbiao; Bai, Dawei; Fu, Fengming; Wu, Hongda; Li, Lijun

    2015-11-01

    ZnO nanowire thin film was synthesized in situ on patterned Zn substrate via a simple and seed-free hydrothermal method. The as-synthesized products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion X-ray analysis(EDS), UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), and photoluminescence (PL) spectroscopy. The time-, temperature- and ammonia concentration-dependent morphology evolution were observed. The results showed that the Zn MPs, in the presence of the reaction solution, can be gradually dissolved, thus providing the Zn source for successive nucleation and growth of ZnO nanowires. The increase of the light absorption as well as a red shift of the band edge was related to the increase of the quantity and the defects of ZnO nanowires. A growth mechanism was proposed to understand the formation of ZnO nanowires on the plated Zn substrate. Under UV irradiation, the as-synthesized ZnO nanowire film exhibited good photocatalytic activity and high photochemistry stability in a wide pH range of 5-10. Furthermore, the ZnO nanowire film can be easily separated, demonstrating great potential for practical application in the degradation of the organic pollutant while exhibiting high reusability.

  15. Tunable band offset and recombination in ZnO nanowire-CdTe quantum dot heterostructures

    Science.gov (United States)

    He, Haiping; Gan, Lu; Sun, Luwei; Ye, Zhizhen

    2017-10-01

    ZnO nanowire (NW)-CdTe quantum dot (QD) type-II heterostructures were constructed using hydrothermally grown ZnO and colloidal CdTe QDs. Photoluminescence (PL) spectroscopy was used to investigate the charge transfer and band offset between CdTe QDs and ZnO NWs. The results demonstrated that the PL shows obvious redshift and prolonged lifetime in the heterostructure, indicating that it originates from recombination between electrons localized in ZnO and holes localized in CdTe. The results reveal that the band offset and charge recombination can be tuned by the growth time or size of CdTe QDs. Our results demonstrate that PL can be a useful tool to evaluate the band alignment and charge recombination in type-II semiconductor heterostructures.

  16. Piezoelectric Nanogenerator Using p-Type ZnO Nanowire Arrays

    KAUST Repository

    Lu, Ming-Pei

    2009-03-11

    Using phosphorus-doped ZnO nanowire (NW) arrays grown on silicon substrate, energy conversion using the p-type ZnO NWs has been demonstrated for the first time. The p-type ZnO NWs produce positive output voltage pulses when scanned by a conductive atomic force microscope (AFM) in contact mode. The output voltage pulse is generated when the tip contacts the stretched side (positive piezoelectric potential side) of the NW. In contrast, the n-type ZnO NW produces negative output voltage when scanned by the AFM tip, and the output voltage pulse is generated when the tip contacts the compressed side (negative potential side) of the NW. In reference to theoretical simulation, these experimentally observed phenomena have been systematically explained based on the mechanism proposed for a nanogenerator. © 2009 American Chemical Society.

  17. Nonvolatile memory functionality of ZnO nanowire transistors controlled by mobile protons.

    Science.gov (United States)

    Yoon, Jongwon; Hong, Woong-Ki; Jo, Minseok; Jo, Gunho; Choe, Minhyeok; Park, Woojin; Sohn, Jung Inn; Nedic, Stanko; Hwang, Hyungsang; Welland, Mark E; Lee, Takhee

    2011-01-25

    We demonstrated the nonvolatile memory functionality of ZnO nanowire field effect transistors (FETs) using mobile protons that are generated by high-pressure hydrogen annealing (HPHA) at relatively low temperature (400 °C). These ZnO nanowire devices exhibited reproducible hysteresis, reversible switching, and nonvolatile memory behaviors in comparison with those of the conventional FET devices. We show that the memory characteristics are attributed to the movement of protons between the Si/SiO(2) interface and the SiO(2)/ZnO nanowire interface by the applied gate electric field. The memory mechanism is explained in terms of the tuning of interface properties, such as effective electric field, surface charge density, and surface barrier potential due to the movement of protons in the SiO(2) layer, consistent with the UV photoresponse characteristics of nanowire memory devices. Our study will further provide a useful route of creating memory functionality and incorporating proton-based storage elements onto a modified CMOS platform for FET memory devices using nanomaterials.

  18. The Influence of Short-Range Correlation on the Phonon Confinement of a Single ZnO Nanowire

    Science.gov (United States)

    Shih, Po-Hsun; Wu, Sheng Yun

    2017-04-01

    Plenty of researches have been performed to probe the diverse properties of ZnO nanowires, but only a few have focused on the physical properties of a single nanowire since to analyze the optical confinement and their correlation lengths along a single nanowire is difficult. In this study, a single ZnO nanowire was synthesized using a Ti-assisted chemical vapor deposition (CVD) method to avoid the appearance of catalytic contamination. Confocal Raman spectroscopy is a powerful tool for probing the phonon confinement effect in a single ZnO nanowire. A confinement model was used to calculate the correlation lengths along the growth direction. The Raman mapping of ZnO nanowires was obtained by a confocal Raman spectrometer. A phonon confinement model was used to fit the Raman curves of the E2 mode and to obtain the correlation lengths along the growth direction of the ZnO nanowire. The correlation lengths are related to the phonon confined region by boundaries and/or defects.

  19. Title: using alignment and 2D network simulations to study charge transport through doped ZnO nanowire thin film electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Phadke, Sujay [Dept. of Mechanical Engineering, Stanford University, 476 Lomita Mall, Stanford, CA 94305 (United States); Lee, Jung-Yong [Korea Advanced Institute of Science and Technology, Graduate School of EEWS, Daejon 305-701 (Korea, Republic of); West, Jack; Salleo, Alberto [Dept. of Materials Science and Engineering, Stanford University, 476 Lomita Mall, Stanford, CA 94305 (United States); Peumans, Peter [Dept. of Electrical Engineering, Stanford University, 330 Serra Mall, Stanford, CA 94305 (United States)

    2011-12-20

    Factors affecting charge transport through ZnO nanowire mat films were studied by aligning ZnO nanowires on substrates and coupling experimental measurements with 2D nanowire network simulations. Gallium doped ZnO nanowires were aligned on thermally oxidized silicon wafer by shearing a nanowire dispersion in ethanol. Sheet resistances of nanowire thin films that had current flowing parallel to nanowire alignment direction were compared to thin films that had current flowing perpendicular to nanowire alignment direction. Perpendicular devices showed {proportional_to}5 fold greater sheet resistance than parallel devices supporting the hypothesis that aligning nanowires would increase conductivity of ZnO nanowire electrodes. 2-D nanowire network simulations of thin films showed that the device sheet resistance was dominated by inter-wire contact resistance. For a given resistivity of ZnO nanowires, the thin film electrodes would have the lowest possible sheet resistance if the inter-wire contact resistance was one order of magnitude lower than the single nanowire resistance. Simulations suggest that the conductivity of such thin film devices could be further enhanced by using longer nanowires. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Reconstruction of perfect ZnO nanowires facets with high optical quality

    Science.gov (United States)

    Zehani, E.; Hassani, S.; Lusson, A.; Vigneron, J.; Etcheberry, A.; Galtier, P.; Sallet, V.

    2017-07-01

    ZnO nanowires were grown on sapphire substrates using metalorganic chemical vapor deposition. The samples were subsequently annealed under zinc pressure in a vacuum-sealed ampoule, at temperature ranging from 500 to 800 °C. The originality and the main motivation to provide a zinc-rich atmosphere were to prevent the out-diffusion of zinc from the nanowires. In doing so, the perfect structural properties and the morphology of the nanowires are kept. Interestingly, photoluminescence experiments performed on nanowires annealed in a narrow window of temperature [580-620 °C] show a spectacular improvement of the optical quality, as transitions commonly observable in high quality bulk samples are found. In addition, the intensity of the so-called "surface excitons" (SX) is strongly decreased. To accurately investigate the chemical modifications of the surface, XPS experiments were carried out and show that zinc hydroxide species and/or Zn(OH)2 sublayer were partially removed from the surface. These results suggest that the annealing process in zinc vapor helps to properly reconstruct the surface of ZnO nanowires, and improves the optical quality of their core. Such a thermal treatment at moderate temperature should be beneficial to nanodevices involving surface reaction, e.g. gas sensors.

  1. Enhanced Photocatalytic Activity of Iron-Doped ZnO Nanowires for Water Purification

    Directory of Open Access Journals (Sweden)

    Yamina Ghozlane Habba

    2017-11-01

    Full Text Available In order to improve the photocatalytic efficiency of ZnO nanowires, iron-doped ZnO nanowires (ZnO:Fe NWs were successfully synthesized. The morphology, optical properties and photocatalytic performance of ZnO:Fe NWs were studied by scanning electron microscopy (SEM, UV-Visible spectrophotometry and photoluminescence spectroscopy (PL, respectively. The SEM observations showed that the morphology of the ZnO NWs was not modified by iron doping, but the band gap was reduced from 3.29 eV for ZnO NWs to 3.25 eV for ZnO:Fe NWs. This band gap reduction allows the semiconductor to harvest more photons to excite more electrons in the valence band; subsequently, resulting in an improvement of the degradability of the understudied organic dyes: methylene blue (MB, methyl orange (MO, and acid red 14 (AR14. The photocatalytic study showed that the photo-degradation rate of the MB, MO, and AR14 was improved 9%, 20%, and 5% respectively by 1% iron doping in the ZnO NWs.

  2. In-situ optical transmission electron microscope study of exciton phonon replicas in ZnO nanowires by cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shize [International Center for Quantum Materials, School of Physics, Peking University and Collaborative Innovation Center of Quantum Matter, Beijing (China); Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Tian, Xuezeng; Wang, Lifen; Wei, Jiake; Qi, Kuo; Li, Xiaomin; Xu, Zhi, E-mail: xuzhi@iphy.ac.cn, E-mail: xdbai@iphy.ac.cn, E-mail: egwang@pku.edu.cn; Wang, Wenlong; Zhao, Jimin; Bai, Xuedong, E-mail: xuzhi@iphy.ac.cn, E-mail: xdbai@iphy.ac.cn, E-mail: egwang@pku.edu.cn [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Enge, E-mail: xuzhi@iphy.ac.cn, E-mail: xdbai@iphy.ac.cn, E-mail: egwang@pku.edu.cn [International Center for Quantum Materials, School of Physics, Peking University and Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2014-08-18

    The cathodoluminescence spectrum of single zinc oxide (ZnO) nanowires is measured by in-situ optical Transmission Electron Microscope. The coupling between exciton and longitudinal optical phonon is studied. The band edge emission varies for different excitation spots. This effect is attributed to the exciton propagation along the c axis of the nanowire. Contrary to free exciton emission, the phonon replicas are well confined in ZnO nanowire. They travel along the c axis and emit at the end surface. Bending strain increases the relative intensity of second order phonon replicas when excitons travel along the c-axis.

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

    KAUST Repository

    Labouchere, Philippe

    2014-04-23

    A hierarchical host-guest nanostructured photoanode is reported for dye-sensitized solar cells. It is composed of ZnO nanowires grown in situ into the macropores of a 3D ZnO inverse opal structure, which acts both as a seed layer and as a conductive backbone host. Using a combination of self-assembly, hydrothermal or electrodeposition of single crystalline ZnO nanowires and TiO2 passivation, a novel photoanode with scattering capability for optimal light harvesting is fabricated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Integration of ZnO and CuO nanowires into a thermoelectric module

    Directory of Open Access Journals (Sweden)

    Dario Zappa

    2014-06-01

    Full Text Available Zinc oxide (ZnO, n-type and copper oxide (CuO, p-type nanowires have been synthesized and preliminarily investigated as innovative materials for the fabrication of a proof-of-concept thermoelectric device. The Seebeck coefficients, electrical conductivity and thermoelectric power factors (TPF of both semiconductor materials have been determined independently using a custom experimental set-up, leading to results in agreement with available literature with potential improvement. Combining bundles of ZnO and CuO nanowires in a series of five thermocouples on alumina leads to a macroscopic prototype of a planar thermoelectric generator (TEG unit. This demonstrates the possibility of further integration of metal oxide nanostructures into efficient thermoelectric devices.

  5. Comparison between ZnO nanowires grown by chemical vapor deposition and hydrothermal synthesis

    Science.gov (United States)

    Podrezova, L. V.; Porro, S.; Cauda, V.; Fontana, M.; Cicero, G.

    2013-11-01

    Vertically aligned zinc oxide nanowires (NWs) were synthesized by two different techniques: chemical vapor deposition (CVD) and hydrothermal synthesis. To compare the effects of different growth conditions, both F-doped SnO2 (FTO) coated-glass and silicon wafers were used as substrates. Before NWs growth, all the substrates were covered with a ZnO seed layer film obtained with the same procedure, which acts as nucleation site for the subsequent growth of the nanowires both during CVD and hydrothermal synthesis. We studied the influence of the two synthesis techniques and the growth duration on the final morphology, orientation, and density of the ZnO NWs using electron microscopy and X-ray diffraction, while the NWs optical quality was addressed by UV-Vis spectroscopy. By discussing advantages and disadvantages of both synthesis methods, we finally show that the application purpose often drives the choice of the NWs growth process and the substrate to be used.

  6. Size-selected growth of transparent well-aligned ZnO nanowire arrays.

    Science.gov (United States)

    Yu, Junsheng; Yuan, Zhaolin; Han, Shijiao; Ma, Zhu

    2012-09-21

    This paper reports the effect of precursor concentration, growth temperature, and growth time on the size and density of ZnO nanowire arrays (ZNAs). The well-aligned ZNAs were grown on indium tin oxide substrate using a facile chemical bath deposition method. The results showed that the ZnO nanowires could be tailored to the desired sizes with a simple variation of the growth parameters. Optical transmission spectra revealed a sufficient transparency of the ZNAs, qualifying them for photovoltaic and other optoelectronic applications. An inverted hybrid solar cell was fabricated using the ZNAs as the electron collecting layer, and the solar cell exhibited a power conversion efficiency of 0.91%.

  7. Enhanced output voltage generation via ZnO nanowires (50 nm): Effect of diameter thinning on voltage enhancement

    Science.gov (United States)

    Ahmad, Mansoor; Iqbal, Muhammad Azhar; Kiely, Janice; Luxton, Richard; Jabeen, Musarrat

    2017-05-01

    50 nm ZnO nanowires were grown on indium tin oxide (ITO) coated poly ethylene terephthalate (PET) substrates by adapting facile aqueous growth technique using low temperature and vacuum conditions. Prior to growth of ZnO nanowires, pure hexagonal wurtzite structured seed layer was grown on flexible substrates. Surface morphology of nanostructure has been examined by scanning electron microscopy (SEM). Vertical growth orientation has been evidenced in XRD patterns. Minute external mechanical force ( 50 nN) has produced periodic voltage peaks. 2.5 nm and 7.5 nm thick sputtered Pt electrode have been tested to obtain output voltages. 50 nm ZnO nanowires has produced a maximum output voltage of 2.717 volts having an output power density of 397.1 mW/cm2. By squeezing the diameter, we have reduced reverse leakage current through nanowires and enhanced output voltage.

  8. Direct synthesis of vertically aligned ZnO nanowires on FTO substrates using a CVD method and the improvement of photovoltaic performance

    Science.gov (United States)

    2012-01-01

    In this work, we report a direct synthesis of vertically aligned ZnO nanowires on fluorine-doped tin oxide-coated substrates using the chemical vapor deposition (CVD) method. ZnO nanowires with a length of more than 30 μm were synthesized, and dye-sensitized solar cells (DSSCs) based on the as-grown nanowires were fabricated, which showed improvement of the device performance compared to those fabricated using transferred ZnO nanowires. Dependence of the cell performance on nanowire length and annealing temperature was also examined. This synthesis method provided a straightforward, one-step CVD process to grow relatively long ZnO nanowires and avoided subsequent nanowire transfer process, which simplified DSSC fabrication and improved cell performance. PMID:22673046

  9. Substrate-free fabrication of self-supporting ZnO nanowire arrays.

    Science.gov (United States)

    Wang, Lisheng; Tsan, Derek; Stoeber, Boris; Walus, Konrad

    2012-08-02

    Thin films composed of self-supporting ZnO nanowire arrays are fabricated via a hydrothermal approach without the presence of any substrates. The films can be transferred and bonded to an arbitrary substrate for device applications. As a demonstration, a piezoelectric converter is made which is able to generate electric charge under compressive forces. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Flexible Dye-Sensitized Solar Cell Based on Vertical ZnO Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Chu Sheng

    2011-01-01

    Full Text Available Abstract Flexible dye-sensitized solar cells are fabricated using vertically aligned ZnO nanowire arrays that are transferred onto ITO-coated poly(ethylene terephthalate substrates using a simple peel-off process. The solar cells demonstrate an energy conversion efficiency of 0.44% with good bending tolerance. This technique paves a new route for building large-scale cost-effective flexible photovoltaic and optoelectronic devices.

  11. Chemical bath deposited PbS thin films on ZnO nanowires for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Gertman, Ronen [Dept of Chemistry, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Osherov, Anna; Golan, Yuval [Dept of Materials Engineering, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Visoly-Fisher, Iris, E-mail: irisvf@bgu.ac.il [Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sede Boqer Campus 84990 (Israel)

    2014-01-01

    Photovoltaic devices usually exploit mid-range band-gap semiconductors which absorb in the visible range of the solar spectrum. However, much energy is lost in the IR and near-IR range. We combined the advantages of small band-gap, bulk-like PbS deposited by facile, cheap and direct chemical bath deposition (CBD), with the good electronic properties of ZnO and the large surface area of nanowires, towards low cost photovoltaic devices utilizing IR and near-IR light. Surprisingly, CBD of PbS on ZnO, and particularly on ZnO nanowires, was not studied hitherto. Therefore, the mechanism of PbS growth by chemical bath deposition on ZnO nanowires was studied in details. A visible proof is shown for a growth mechanism starting from amorphous Pb(OH){sub 2} layer, that evolved into the ‘ion-by-ion’ growth mechanism. The growth mechanism and the resulting morphology at low temperatures were controlled by the thiourea concentration. The grain size affected the magnitude of the band-gap and was controlled by the deposition temperatures. Deposition above 40 °C resulted in bulk-like PbS with an optical band-gap of 0.4 eV. Methods were demonstrated for achieving complete PbS coverage of the complex ZnO NW architecture, a crucial requirement in optoelectronic devices to prevent shorts. Measurements of photocurrents under white and near-IR (784 nm) illumination showed that despite a 200 meV barrier for electron transfer at the PbS/ZnO interface, extraction of photo-electrons from PbS to the ZnO was feasible. The ability to harvest electrons from a narrow band-gap semiconductor deposited on a large surface-area electrode can advance the field towards high efficiency, low cost IR and near-IR sensors and third generation solar cells. - Highlights: • PbS was deposited on ZnO nanowires using chemical bath deposition. • At 50 °C the growth mechanism starts from an amorphous Pb(OH){sub 2} layer. • At 5 °C the growth mechanism of PbS can be controlled by thiourea concentrations

  12. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Demes, Thomas [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Ternon, Céline, E-mail: celine.ternon@grenoble-inp.fr [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, LTM, F-38000 Grenoble (France); Morisot, Fanny [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Riassetto, David [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Legallais, Maxime [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Roussel, Hervé; Langlet, Michel [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France)

    2017-07-15

    Highlights: • ZnO nanowires are grown on sol-gel ZnO seed layers by hydrothermal synthesis. • Ultra-thin and high aspect ratio nanowires are obtained without using additives. • Nanowire diameter is 20–25 nm regardless of growth time and seed morphology. • A nanowire growth model is developed on the basis of thermodynamic considerations. • The nanowires are intended for integration into electrically conductive nanonets. - Abstract: Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20–25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20–25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  13. Gallium ion implantation greatly reduces thermal conductivity and enhances electronic one of ZnO nanowires

    Directory of Open Access Journals (Sweden)

    Minggang Xia

    2014-05-01

    Full Text Available The electrical and thermal conductivities are measured for individual zinc oxide (ZnO nanowires with and without gallium ion (Ga+ implantation at room temperature. Our results show that Ga+ implantation enhances electrical conductivity by one order of magnitude from 1.01 × 103 Ω−1m−1 to 1.46 × 104 Ω−1m−1 and reduces its thermal conductivity by one order of magnitude from 12.7 Wm−1K−1 to 1.22 Wm−1K−1 for ZnO nanowires of 100 nm in diameter. The measured thermal conductivities are in good agreement with those in theoretical simulation. The increase of electrical conductivity origins in electron donor doping by Ga+ implantation and the decrease of thermal conductivity is due to the longitudinal and transverse acoustic phonons scattering by Ga+ point scattering. For pristine ZnO nanowires, the thermal conductivity decreases only two times when its diameter reduces from 100 nm to 46 nm. Therefore, Ga+-implantation may be a more effective method than diameter reduction in improving thermoelectric performance.

  14. Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2011-08-01

    Full Text Available This paper presents a prototype wireless remote glucose monitoring system interfaced with a ZnO nanowire arrays-based glucose sensor, glucose oxidase enzyme immobilized onto ZnO nanowires in conjunction with a Nafion® membrane coating, which can be effectively applied for the monitoring of glucose levels in diabetics. Global System for Mobile Communications (GSM services like General Packet Radio Service (GPRS and Short Message Service (SMS have been proven to be logical and cost effective methods for gathering data from remote locations. A communication protocol that facilitates remote data collection using SMS has been utilized for monitoring a patient’s sugar levels. In this study, we demonstrate the remote monitoring of the glucose levels with existing GPRS/GSM network infra-structures using our proposed functionalized ZnO nanowire arrays sensors integrated with standard readily available mobile phones. The data can be used for centralized monitoring and other purposes. Such applications can reduce health care costs and allow caregivers to monitor and support to their patients remotely, especially those located in rural areas.

  15. Wireless remote monitoring of glucose using a functionalized ZnO nanowire arrays based sensor.

    Science.gov (United States)

    Ali, Syed M Usman; Aijazi, Tasuif; Axelsson, Kent; Nur, Omer; Willander, Magnus

    2011-01-01

    This paper presents a prototype wireless remote glucose monitoring system interfaced with a ZnO nanowire arrays-based glucose sensor, glucose oxidase enzyme immobilized onto ZnO nanowires in conjunction with a Nafion® membrane coating, which can be effectively applied for the monitoring of glucose levels in diabetics. Global system for mobile communications (GSM) services like general packet radio service (GPRS) and Short Message Service (SMS) have been proven to be logical and cost effective methods for gathering data from remote locations. A communication protocol that facilitates remote data collection using SMS has been utilized for monitoring a patient's sugar levels. In this study, we demonstrate the remote monitoring of the glucose levels with existing GPRS/GSM network infra-structures using our proposed functionalized ZnO nanowire arrays sensors integrated with standard readily available mobile phones. The data can be used for centralized monitoring and other purposes. Such applications can reduce health care costs and allow caregivers to monitor and support to their patients remotely, especially those located in rural areas.

  16. Structural and optical characterization of ZnO nanowires grown on alumina by thermal evaporation method.

    Science.gov (United States)

    Mute, A; Peres, M; Peiris, T C; Lourenço, A C; Jensen, Lars R; Monteiro, T

    2010-04-01

    Zinc oxide nanowires have been grown on alumina substrate by thermal evaporation of zinc nanopowder in the presence of oxygen flow. The growth was performed under ambient pressure and without the use of foreign catalyst. Scanning electron microscopy (SEM) observation showed that the as-grown sample consists of bulk ZnO crystal on the substrate surface with nanowires growing from this base. Growth mechanism of the observed morphology is suggested to be governed by the change of zinc vapour supersaturation during the growth process. X-ray diffraction (XRD) measurement was used to identify the crystalline phase of the nanowires. Optical properties of the nanowires were investigated using Raman scattering and photoluminescence (PL). The appearance of dominant, Raman active E2 (high) phonon mode in the Raman spectrum has confirmed the wurtzite hexagonal phase of the nanowires. With above bandgap excitation the low temperature PL recombination is dominated by donor bound exciton luminescence at -3.37 eV with a narrow full width at half maximum. Free exciton emission is also seen at low temperature and can be observed up to room temperature. The optical data indicates that the grown nanowires have high optical quality.

  17. Surface morphology evolution with fabrication parameters of ZnO nanowires toward emission properties enhancement

    Science.gov (United States)

    Belhaj, Marwa; Dridi, Cherif; Habba, Yamina Ghozlene; Capo-Chichi, Martine; Leprince-Wang, Yamin

    2017-12-01

    ZnO nanowire (NW) arrays were successfully grown on pre-seeded indium Tin oxide (ITO)-coated glass substrate using hydrothermal synthesis. Herein, the effects of ZnO seed layer density on the performance of ZnO NWs were investigated in details. The orientation and the dimension of ZnO NWs were found to depend on seeded substrate density as shown by scanning electron microscopy (SEM) micrographs which revealed that the typical morphology with the most uniform size can be obtained. From the X-ray diffraction (XRD) measurement, it can be seen that hexagonal c -axis oriented NWs were grown. The resonant Raman scattering was also investigated in details. It confirmed the wurtzite structure of the NW arrays and expected for good optical properties. The optical band gaps of synthesized ZnO NWs were found to decrease comparing to bulk ZnO and as function of seed layer. The photoluminescence (PL) spectra at room temperature have shown strong UV excitonic emission and weak deep-level emissions which reveal that the as-grown NW arrays have good optical properties with limited deep-level defects.

  18. The Modulation of Optical Property and its Correlation with Microstructures of ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    Hope Greg

    2009-01-01

    Full Text Available Abstract ZnO nanowires with both good crystallinity and oxygen vacancies defects were synthesized by thermal oxidation of Zn substrate pretreated in concentrated sulfuric acid under the air atmosphere, Ar- and air-mixed gas stream. The photoluminescence spectra reveal that only near-band-edge (NBE emission peak was observed for the sample grown in the air atmosphere; the broad blue–green and the red-shifted NBE emission peaks were observed for the sample grown in the mixed gas stream, indicating that the sample grown in the mixed gas stream has a defective structure and its optical properties can be modulated by controlling its structure. The high-resolution transmission electron microscope and the corresponding structural simulation confirm that the oxygen vacancies exist in the crystal of the nanowires grown in the mixed gas stream. The ZnO nanowires with oxygen vacancies defects exhibit better photocatalytic activity than the nanowires with good crystallinity. The photocatalytic process obeys the rules of first-order kinetic reaction, and the rate constants were calculated.

  19. Room Temperature Ferromagnetism of (Mn,Fe Codoped ZnO Nanowires Synthesized by Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Yongqin Chang

    2011-01-01

    Full Text Available (Mn,Fe codoped ZnO nanowires were synthesized on silicon substrates in situ using a chemical vapor deposition method. The structure and property of the products were investigated by X-ray, electron microscopy, Raman, photoluminescence, and superconducting quantum interference device magnetometer. The doped nanowires are of pure wurtzite phase with single crystalline, and the elements distribute homogeneously in the doped nanowires. Photoluminescence spectrum of the doped nanowires is dominated by a deep-level emission with a negligible near-band-edge emission. The magnetic hysteresis curve with a coercive field of 35 Oe is clearly observed at 300 K, resulting from room-temperature ferromagnetic ordering in the (Mn,Fe codoped ZnO nanowires, which has great potential applications for spintronics devices.

  20. Growth of ZnO nanowires on polypropylene membrane surface-Characterization and reactivity

    Science.gov (United States)

    Bojarska, Marta; Nowak, Bartosz; Skowroński, Jarosław; Piątkiewicz, Wojciech; Gradoń, Leon

    2017-01-01

    Need for a new membrane is clearly visible in recent studies, mostly due to the fouling phenomenon. Authors, focused on problem of biofouling caused by microorganisms that are present in water environment. An attempt to form a new membrane with zinc oxide (ZnO) nanowires was made; where plasma treatment was used as a first step of modification followed by chemical bath deposition. Such membrane will exhibit additional reactive properties. ZnO, because of its antibacterial and photocatalytic properties, is more and more often used in commercial applications. The authors used SEM imaging, measurement of the contact angle, XRD and the FT-IR analysis for membrane characterization. Amount of ZnO deposited on membrane surface was also investigated by dithizone method. Photocatalytic properties of such membranes were examined through methylene blue and humic acid degradation in laboratory scale modules with LEDs as either: wide range white or UV light source. Antibacterial and antifouling properties of polypropylene membranes modified with ZnO nanowires were examined through a series of tests involving microorganisms: model gram-positive and -negative bacteria. The obtained results showed that it is possible to modify the membrane surface in such a way, that additional reactive properties will be given. Thus, not only did the membrane become a physical barrier, but also turned out to be a reactive one.

  1. Pressure-Induced Structural Transformations of ZnO Nanowires Probed by X-ray Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Zhaohui; Zhuravlev, Kirill K.; Morin, Stephen A.; Li, Linsen; Jin, Song; Song, Yang (UW); (UWO)

    2016-01-11

    ZnO nanowires were investigated at high pressures of up to 27 GPa in situ in a diamond anvil cell using synchrotron X-ray diffraction. Upon compression, a wurtzite-to-rocksalt phase transformation was observed, but both the onset and the completion pressures of this transformation were enhanced compared with all previously studied morphologies of ZnO, including nanocrystals and their bulk counterparts. Upon decompression, the rocksalt phase was found to sustain at near ambient pressure and could be recovered in a significant amount. Moreover, the pressure-volume equations of state for both the wurtzite and the rocksalt phases indicate that their bulk moduli are significantly higher than those of bulk ZnO and nanocrystals. The SEM images of the ZnO nanowires both before and after the compression suggest the pressure-induced morphology modifications, corroborating the understanding of other structure and property evolutions with pressure. Finally, possible pressure-induced phase transition mechanisms were explored by examining the cell parameters and the internal structural parameter with pressures.

  2. Effects of Oxygen Vacancy on Optical and Electrical Properties of ZnO Bulks and Nanowires

    Science.gov (United States)

    Yu, Xiao-Xia; Zheng, Hong-Mei; Fang, Xiao-Yong; Jin, Hai-Bo; Cao, Mao-Sheng

    2014-11-01

    Based on the generalized gradient approximation (GGA) in density functional theory (DFT) and using the first-principle plane wave ultrasoft pseudopotential method, we construct and optimize the structures of intrinsic and oxygen vacancy (VO) ZnO bulks and nanowires (NWs) in the Castep module. Moreover, the calculation of band structures and the optical properties are carried out. The calculated results exhibit that the oxygen vacancy exerts a more significant influence on the electronic structures of the ZnO bulks instead of the NWs. What is more, the influences of the VO on the optical properties are mainly embodied in the ultraviolet region, and the main optical parameters of ZnO bulks and NWs with VO are anisotropic.

  3. A Flexible Blue Light-Emitting Diode Based on ZnO Nanowire/Polyaniline Heterojunctions

    Directory of Open Access Journals (Sweden)

    Y. Y. Liu

    2013-01-01

    Full Text Available An organic/inorganic light-emitting diode (LED consisting of n-type vertically aligned ZnO nanowires (NWs and p-type proton acid doped polyaniline (PANi is reported. The device was fabricated on flexible indium-tin-oxide (ITO coated polyethylene terephthalate (PET substrate. A broad blue light emission band ranging from 390 nm to 450 nm was observed in the electroluminescence (EL spectra of the device, which was related to the interface recombination of electrons in the conduction band of ZnO NWs and holes in the polaron level of PANi. The turn-on voltage of the device is ~3.5 V, lower than most of ZnO NWs based LED devices. In combination with the easy fabrication, flexibility, low power consumption, and mechanical robustness, this novel device is very promising in the application of blue LEDs.

  4. Growth of Horizonatal ZnO Nanowire Arrays on Any Substrate

    KAUST Repository

    Qin, Yong

    2008-12-04

    A general method is presented for growing laterally aligned and patterned ZnO nanowire (NW) arrays on any substrate as long as it is flat. The orientation control is achieved using the combined effect from ZnO seed layer and the catalytically inactive Cr (or Sn) layer for NW growth. The growth temperature (< 100 °C) is so low that the method can be applied to a wide range of substrates that can be inorganic, organic, single crystal, polycrystal, or amorphous. The laterally aligned ZnO NW arrays can be employed for various applications, such as gas sensor, field effect transistor, nanogenerator, and flexible electronics. © 2008 American Chemical Society.

  5. Preparation and Characteristic of Relative-Humidity Sensors Based on Laterally Grown ZnO Nanowires

    Science.gov (United States)

    Tsai, Fu-Shou; Wang, Shui-Jinn; Tu, Yung-Chun; Lin, Tseng-Hsing

    2013-06-01

    The use of laterally oriented zinc oxide nanowires (ZnO NWs) grown by a hydrothermal growth (HTG) method for relative-humidity (RH) sensing devices at room temperature (RT) is demonstrated. Sensing response under various RH conditions (12-96%) at RT is presented and discussed. A humidity sensor based on laterally oriented ZnO NWs with a sensing response (R12%/R96%) as high as 2.2 was obtained at RT. The RT-operable humidity-sensing characteristics with comparably good sensitivity of the proposed humidity sensors is attributed to the full utilization of the entire NW surface, because the current path is aligned with the orientation of the bridged lateral ZnO NWs during the humidity sensing application, thus making possible.

  6. Recent Progress in Ohmic/Schottky-Contacted ZnO Nanowire Sensors

    Directory of Open Access Journals (Sweden)

    Xiaoli Zhao

    2015-01-01

    Full Text Available We review the recent progress of zinc oxide (ZnO nanowire sensors with ohmic-contacted and Schottky-contacted configurations and the enhancement of the performances of Schottky-contacted ZnO NW sensors (SCZNSs by the piezotronic effect. Comparing with the traditional ohmic-contacted ZnO NW sensors (OCZNSs, the SCZNSs have higher sensitivities and faster responses controlled by the barrier height at the metal-semiconductor (M-S interface. The piezotronic effect was applied to tune the Schottky barrier height (SBH with the strain-induced piezoelectric polarization charges at the interface of the M-S contact. The piezotronic effect can thus improve the detection limitation, sensitivity, and response time of the SCZNSs in different applications, such as UV detection, gas and bio/chemical sensing. These piezotronic-enhanced SCZNSs may find potential applications in human-machine interfacing and flexible electronics skin technologies.

  7. Growth and Transfer of Monolithic Horizontal ZnO Nanowire Superstructures onto Flexible Substrates

    KAUST Repository

    Xu, Sheng

    2010-04-28

    A method of fabricating horizontally aligned ZnO nanowire (NW) arrays with full control over the width and length is demonstrated. A cross-sectional view of the NWs by transmission electron microscopy shows a "mushroom-like" structure. Novel monolithic multisegment superstructures are fabricated by making use of the lateral overgrowth. Ultralong horizontal ZnO NWs of an aspect ratio on the order often thousand are also demonstrated. These horizontal NWs are lifted off and transferred onto a flexible polymer substrate, which may have many great applications in horizontal ZnO NW-based nanosensor arrays, light-emitting diodes, optical gratings, integrated circuit interconnects, and high-output-power alternating-current nanogenerators. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.

  8. Growth of antimony doped P-type zinc oxide nanowires for optoelectronics

    Science.gov (United States)

    Wang, Zhong Lin; Pradel, Ken

    2016-09-27

    In a method of growing p-type nanowires, a nanowire growth solution of zinc nitrate (Zn(NO.sub.3).sub.2), hexamethylenetetramine (HMTA) and polyethylenemine (800 M.sub.w PEI) is prepared. A dopant solution to the growth solution, the dopant solution including an equal molar ration of sodium hydroxide (NaOH), glycolic acid (C.sub.2H.sub.4O.sub.3) and antimony acetate (Sb(CH.sub.3COO).sub.3) in water is prepared. The dopant solution and the growth solution combine to generate a resulting solution that includes antimony to zinc in a ratio of between 0.2% molar to 2.0% molar, the resulting solution having a top surface. An ammonia solution is added to the resulting solution. A ZnO seed layer is applied to a substrate and the substrate is placed into the top surface of the resulting solution with the ZnO seed layer facing downwardly for a predetermined time until Sb-doped ZnO nanowires having a length of at least 5 .mu.m have grown from the ZnO seed layer.

  9. Electrophoretic deposition of ZnO nanostructures: Au nanoclusters on Si substrates induce self-assembled nanowire growth

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval, Claudia [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Marin, Oscar [CONICET – LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Real, Silvina [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Comedi, David [CONICET – LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Tirado, Mónica, E-mail: mtirado@herrera.unt.edu.ar [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina)

    2014-09-15

    Highlights: • ZnO nanowires were grown on silicon substrate by electrophoretic deposition technique without use a porous template. • The growth was induced by Au nanoclusters and was performed at room temperature. • The photoluminescence spectrum for the nanowires obtained shows a broad UV-blue excitonic emission peak and a low emission in the green region. - Abstract: The present work reports the self-assembled growth of ZnO nanowires on silicon substrate with nanometer sized Au clusters using electrophoretic deposition technique at room temperature without a sacrificial template. A colloidal suspension of ≈5 nm sized ZnO nanoparticles dispersed in 2-propanol was used (nanoparticle bandgap of 3.47 eV as determined from absorbance measurements). The results show that the Au nanoclusters on the silicon substrate induce the self-assembly of the ZnO nanoparticles into vertically aligned ZnO nanowires. This effect is tentatively explained as being due to increased electric field intensities near the Au nanoclusters during the electrophoretic deposition. Photoluminescence measurements reveal the presence of quantum confined excitons and a relatively low concentration of deep defects in the nanowires. The electric field guided growth of semiconductor nanostructures at room temperature has great industrial potential as it minimizes production costs and enables the use of substrate materials not withstanding high temperatures.

  10. High performance hydrogen sensor based on Mn implanted ZnO nanowires array fabricated on ITO substrate.

    Science.gov (United States)

    Renitta, A; Vijayalakshmi, K

    2017-08-01

    In the present research, we propose a novel approach for the detection of hydrogen gas using Mn implanted ZnO nanowires fabricated onto ITO coated glass substrate by chemical spray pyrolysis deposition. The effect of Mn concentration on the structural, optical and morphological properties of ZnO films were investigated. X-ray diffraction studies showed that the Mn implanted ZnO films were grown as a polycrystalline hexagonal wurtzite phase without any impurities. The (101) peak position of ZnO-Mn films was shifted towards a lower angle with increasing Mn concentration. The optical band gap decreased from 3.45eV to 3.23eV with increasing Mn content. PL spectra, revealed sharp and strong near band edge emission which suggests that ZnO nanowires exhibit high crystalline quality. FE-SEM images of Mn implanted ZnO show perfectly aligned nanowires for all the films fabricated on ITO. The material (Zn, O, Mn) was confirmed by EDX spectra. The hydrogen sensing mechanism of the Mn implanted ZnO nanowire sensor was also discussed. It was found that H2 response was significantly enhanced by more than one order of magnitude with increasing Mn doping concentrations. The studied ZnO-Mn films coated on ITO substrate can be used as a low cost and easy-fabrication hydrogen sensing material. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. ZnO nanowires coated stainless steel meshes as hierarchical photocatalysts for catalytic photodegradation of four kinds of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Fu-Hsiang; Lo, Wei-Ju [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan (China); Chang, Yu-Cheng, E-mail: ychang0127@gmail.com [Department of Materials Science and Engineering, Feng Chia University, Taichung, 40724, Taiwan (China); Guo, Jin-You; Chen, Chien-Ming [Department of Materials Science and Engineering, Feng Chia University, Taichung, 40724, Taiwan (China)

    2016-09-05

    ZnO nanostructures were grown on the stainless steel mesh substrates using an aqueous chemical growth method. The different additives (such as 1,3-diaminopropane and polyethyleneimine) can be used to control the morphology of ZnO nanostructures. ZnO nanowires exhibit very prominent green emission and week UV emission from defect and band gap in the cathodoluminescence spectrum, respectively. The different morphology of ZnO nanostructures on the stainless steel mesh substrates can be used to irradiate UV light for the photocatalytic degradation of four kinds of organic pollutants, such as methylene blue, rhodamine 6G, methyl orange, and 4-nitrophenol. The ZnO nanowires can provide a higher surface-to-volume ratio and stronger defect emission, resulting in their highest photocatalytic performance in 10 W UV light irradiation. The ZnO nanowire arrays on the stainless steel mesh substrates provide a large-scale, facile, low-cost, high surface area, and high photocatalytic efficiency, which shall be of significant value for practical applications of the decomposition of environment pollutants and reusing of wastewater treatment. - Highlights: • ZnO NWs were grown on the stainless steel mesh by aqueous chemical growth method. • Longer ZnO NW arrays have been grown at short reaction time (2 h). • ZnO NWs revealed green emission from surface defect in the CL spectrum. • The different morphologies of ZnO were evaluated organic pollutant degradation. • ZnO NWs were also exhibited great photocatalytic activity and reusability.

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

    Directory of Open Access Journals (Sweden)

    Taylor Curtis

    2010-01-01

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

  13. Wafer-Scale High-Throughput Ordered Growth of Vertically Aligned ZnO Nanowire Arrays

    KAUST Repository

    Wei, Yaguang

    2010-09-08

    This article presents an effective approach for patterned growth of vertically aligned ZnO nanowire (NW) arrays with high throughput and low cost at wafer scale without using cleanroom technology. Periodic hole patterns are generated using laser interference lithography on substrates coated with the photoresist SU-8. ZnO NWs are selectively grown through the holes via a low-temperature hydrothermal method without using a catalyst and with a superior control over orientation, location/density, and as-synthesized morphology. The development of textured ZnO seed layers for replacing single crystalline GaN and ZnO substrates extends the large-scale fabrication of vertically aligned ZnO NW arrays on substrates of other materials, such as polymers, Si, and glass. This combined approach demonstrates a novel method of manufacturing large-scale patterned one-dimensional nanostructures on various substrates for applications in energy harvesting, sensing, optoelectronics, and electronic devices. © 2010 American Chemical Society.

  14. Investigations into the impact of various substrates and ZnO ultra thin seed layers prepared by atomic layer deposition on growth of ZnO nanowire array

    Science.gov (United States)

    Ding, JN; Liu, YB; Tan, CB; Yuan, NY

    2012-07-01

    The impact of various substrates and zinc oxide (ZnO) ultra thin seed layers prepared by atomic layer deposition on the geometric morphology of subsequent ZnO nanowire arrays (NWs) fabricated by the hydrothermal method was investigated. The investigated substrates included B-doped ZnO films, indium tin oxide films, single crystal silicon (111), and glass sheets. Scanning electron microscopy and X-ray diffraction measurements revealed that the geometry and aligment of the NWs were controlled by surface topography of the substrates and thickness of the ZnO seed layers, respectively. According to atomic force microscopy data, we suggest that the substrate, fluctuate amplitude and fluctuate frequency of roughness on ZnO seed layers have a great impact on the alignment of the resulting NWs, whereas the influence of the seed layers' texture was negligible.

  15. Electrical properties of lightly Ga-doped ZnO nanowires

    Science.gov (United States)

    Alagha, S.; Heedt, S.; Vakulov, D.; Mohammadbeigi, F.; Senthil Kumar, E.; Schäpers, Th; Isheim, D.; Watkins, S. P.; Kavanagh, K. L.

    2017-12-01

    We investigated the growth, crystal structure, elemental composition and electrical transport characteristics of ZnO nanowires, a promising candidate for optoelectronic applications in the UV-range. Nominally-undoped and Ga-doped ZnO nanowires were grown by metal-organic chemical vapor deposition. Photoluminescence measurements confirmed the incorporation of Ga via donor-bound exciton emission. With atom-probe tomography we estimated an upper limit of the Ga impurity concentration ({10}18 {{cm}}-3). We studied the electrical transport characteristics of these nanowires with a W-nanoprobe technique inside a scanning electron microscope and with lithographically-defined contacts allowing back-gated measurements. An increase in apparent resistivity by two orders of magnitude with decreasing radius was measured with both techniques with a much larger distribution width for the nanoprobe method. A drop in the effective carrier concentration and mobility was found with decreasing radius which can be attributed to carrier depletion and enhanced scattering due to surface states. Little evidence of a change in resistivity was observed with Ga doping, which indicates that the concentration of native or background dopants is higher than the Ga doping concentration.

  16. Synthesis and photonic property study of ZnO nanowires for a real time photodynamic therapy monitoring probe

    Science.gov (United States)

    Sridhar, D.; Xie, Jining; Abraham, Jose K.; Varadan, Vijay K.

    2007-04-01

    In this paper, we present how the photonic properties of zinc oxide (ZnO) nanowires can be used to potentially advance the effectiveness of Photodynamic therapy (PDT), one of the most recent and promising approaches among cancer therapies. Presently, PDT employs laser light to activate intravenously or topically administered photosensitizers to give rise to highly reactive singlet oxygen which has a very short lifetime and is capable of biochemical damage to cell membranes of the tumor. A probe that can monitor in real time the penetration depth of the laser in the tumor and also the evolution of the singlet oxygen, which is critical for tumor eradication, is capable of improving the efficacy of PDT quite significantly. Such a probe, by providing real time feedback, can help us determine whether to increase or decrease the light exposure dose and also if further local administration of photosensitizers is required or not. ZnO nanowires are known to be photoconductive and recent research also demonstrated the temperature dependence of the photocurrent in the nanowires. They are also sensitive to blue and other near UV spectra which is same range of activation wavelengths of most photosensitizers, and hence making them a good candidate for a potential PDT monitoring probe. ZnO nanowires were fabricated on silicon substrates by vapor phase deposition using e-beam evaporated gold as a catalyst. Control of the dimensions of the nanowires could be achieved by varying the dimensions of the catalyst by means of e-beam evaporation process. Photoluminescence properties of ZnO nanowires were investigated at UV and near UV wavelengths. Further, ZnO is also known for its antimicrobial properties, thereby ruling out any possibility of bacterial infection because of the implanted probe. This study was done to compliment the existing expertise of our research group in the design and fabrication of several nanowire based probes and microsensors specifically for neuroelectronic and

  17. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    Energy Technology Data Exchange (ETDEWEB)

    Pathirane, M., E-mail: minoli.pathirane@uwaterloo.ca; Iheanacho, B.; Lee, C.-H.; Wong, W. S. [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Tamang, A.; Knipp, D. [Research Center for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Bremen 28759 (Germany); Lujan, R. [Electronic Materials and Devices Laboratory, Palo Alto Research Center, Palo Alto, California 93003 (United States)

    2015-10-05

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm–800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact.

  18. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    Science.gov (United States)

    Pathirane, M.; Iheanacho, B.; Tamang, A.; Lee, C.-H.; Lujan, R.; Knipp, D.; Wong, W. S.

    2015-10-01

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm-800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact.

  19. Vertically aligned ZnO nanowire arrays in Rose Bengal-based dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Basudev; Batabyal, Sudip K.; Pal, Amlan J. [Indian Association for the Cultivation of Science, Department of Solid State Physics, Kolkata 700032 (India)

    2007-05-23

    We fabricate dye-sensitized solar cells (DSSC) using vertically oriented, high density, and crystalline array of ZnO nanowires, which can be a suitable alternative to titanium dioxide nanoparticle films. The vertical nanowires provide fast routes or channels for electron transport to the substrate electrode. As an alternative to conventional ruthenium complex, we introduce Rose Bengal dye, which acts as a photosensitizer in the dye-sensitized solar cells. The dye energetically matches the ZnO with usual KI-I{sub 2} redox couple for dye-sensitized solar cell applications. (author)

  20. Low-Temperature Rapid Fabrication of ZnO Nanowire UV Sensor Array by Laser-Induced Local Hydrothermal Growth

    Directory of Open Access Journals (Sweden)

    Sukjoon Hong

    2013-01-01

    Full Text Available We demonstrate ZnO nanowire based UV sensor by laser-induced hydrothermal growth of ZnO nanowire. By inducing a localized temperature rise using focused laser, ZnO nanowire array at ~15 μm size consists of individual nanowires with ~8 μm length and 200~400 nm diameter is readily synthesized on gold electrode within 30 min at the desired position. The laser-induced growth process is consecutively applied on two different points to bridge the micron gap between the electrodes. The resultant photoconductive ZnO NW interconnections display 2~3 orders increase in the current upon the UV exposure at a fixed voltage bias. It is also confirmed that the amount of photocurrent can be easily adjusted by changing the number of ZnO NW array junctions. The device exhibits clear response to the repeated UV illumination, suggesting that this process can be usefully applied for the facile fabrication of low-cost UV sensor array.

  1. Photo-enhanced magnetization in Fe-doped ZnO nanowires

    Science.gov (United States)

    Lorite, I.; Kumar, Y.; Esquinazi, P.; Friedländer, S.; Pöppl, A.; Michalsky, T.; Meijer, J.; Grundmann, M.; Meyer, T.; Estrela-Lopis, I.

    2016-07-01

    An emerging branch of electronics, the optospintronics, would be highly boosted if the control of magnetic order by light is implemented in magnetic semiconductors' nanostructures being compatible with the actual technology. Here, we show that the ferromagnetic magnetization of low Fe-doped ZnO nanowires prepared by carbothermal process is enhanced under illumination up to temperatures slightly below room temperature. This enhancement is related to the existence of an oxygen vacancy VO in the neighborhood of an antiferromagnetic superexchange Fe3+-Fe3+ pair. Under illumination, the VO is ionized to VO + giving an electron to a close Fe3+ ion from the antiferromagnetic pair. This light excited electron transition allows the transition of Fe3+ to Fe2+ forming stable ferromagnetic double exchange pairs, increasing the total magnetization. The results presented here indicate an efficient way to influence the magnetic properties of ZnO based nanostructures by light illumination at high temperatures.

  2. Enhanced H2 sensitivity at room temperature of ZnO nanowires functionalized by Pd nanoparticles

    Science.gov (United States)

    Ren, Shoutian; Fan, Guanghua; Qu, Shiliang; Wang, Qiang

    2011-10-01

    For sensitive detection of H2, ZnO nanowires networks decorated with photo-decomposed Pd nanoparticles were fabricated between femtosecond laser-writing interdigitated electrodes by chemical vapor deposition method. When H2 concentration is increased from 20 to 4000 ppm at room temperature, sensitivity of the sample is increased from 3.7% to 1017.9%. The high sensitivity can be explained by considering the reaction between the adsorbed O2- and the disassociated H atoms facilitated by Pd nanoparticles. This mechanism is further supported by the H2 response results under UV light illumination, which can reduce the amount of O2- on the ZnO surface, leading to depressed sensitivity. The sensor also shows high selectivity, long-term stability, and ultra-low power consumption of nanowatt level, due to the novel fabrication process.

  3. Fabrication of a Miniaturized ZnO Nanowire Accelerometer and Its Performance Tests

    Directory of Open Access Journals (Sweden)

    Hyun Chan Kim

    2016-09-01

    Full Text Available This paper reports a miniaturized piezoelectric accelerometer suitable for a small haptic actuator array. The accelerometer is made with zinc oxide (ZnO nanowire (NW grown on a copper wafer by a hydrothermal process. The size of the accelerometer is 1.5 × 1.5 mm2, thus fitting the 1.8 × 1.8 mm2 haptic actuator array cell. The detailed fabrication process of the miniaturized accelerometer is illustrated. Performance evaluation of the fabricated accelerometer is conducted by comparing it with a commercial piezoelectric accelerometer. The output current of the fabricated accelerometer increases linearly with the acceleration. The miniaturized ZnO NW accelerometer is feasible for acceleration measurement of small and lightweight devices.

  4. Heterojunction photodiode fabricated from hydrogen treated ZnO nanowires grown on p-silicon substrate.

    Science.gov (United States)

    Shao, Dali; Yu, Mingpeng; Lian, Jie; Sawyer, Shayla

    2012-11-19

    A heterojunction photodiode was fabricated from ZnO nanowires (NWs) grown on a p-type Si (100) substrate using a hydrothermal method. Post growth hydrogen treatment was used to improve the conductivity of the ZnO NWs. The heterojunction photodiode showed diode characteristics with low reverse saturation current (5.58 × 10(-7) A), relatively fast transient response, and high responsivity (22 A/W at 363 nm). Experiments show that the photoresponsivity of the photodiode is dependent on the polarity of the voltages. The photoresponsivity of the device was discussed in terms of the band diagrams of the heterojunction and the carrier diffusion process.

  5. Schottky Photodiode Fabricated from Hydrogen-Peroxide-Treated ZnO Nanowires

    Science.gov (United States)

    Lee, Hsin-Yen; Wu, Bin-Kun; Chern, Ming-Yau

    2013-05-01

    An effective, transparent solar-blind Schottky ultraviolet (UV) sensor made of zinc oxide (ZnO) nanowires (NWs) was fabricated by chemical vapor deposition (CVD). Indium-tin oxide (ITO) thin films were deposited by radio frequency (RF) sputtering as Schottky contacts, where the hydrogen peroxide (H2O2) treatment of ZnO NWs played a key role in the rectifying effect. The photodiode showed a fitted barrier height of 0.89 eV, an ideality factor of 1.82, and a rectification behavior of up to three orders of magnitude at a voltage bias between -1 and +1 V. Photoresponse measurement proved a reliable device in the UV region.

  6. CL from ZnO nanowires and microneedles Co-doped with N and Mn

    Science.gov (United States)

    Herrera, M.; Morales, A.; Díaz, J. A.

    2014-05-01

    Cathodoluminescence (CL) was used to study the luminescence emission of ZnO : N, Mn nanowires and microneedles grown by thermal evaporation. CL spectra acquired at room temperature showed the presence of near band edge and defect-related emissions. The defect related emission comprised two bands centered at 2.28 and 2.5 eV. The first component was attributed to the formation of spinel ZnMn2O4 and the second to the well-known ZnO green emission. CL spectra acquired at 100 K showed two emissions centered at 3.22 and 3.25 eV that were attributed to donor-acceptor pair (DAP) and FA transitions, respectively. It was proposed that substitutional nitrogen (NO) and zinc interstitial (Zni) were acceptor and shallow-donor centers in the DAP transition.

  7. Fabrication and characterization of ultraviolet photosensors from ZnO nanowires prepared using chemical bath deposition method

    Science.gov (United States)

    Al-Asadi, Ahmed S.; Henley, Luke Alexander; Ghosh, Sujoy; Quetz, Abdiel; Dubenko, Igor; Pradhan, Nihar; Balicas, Luis; Perea-Lopez, Nestor; Carozo, Victor; Lin, Zhong; Terrones, Mauricio; Talapatra, Saikat; Ali, Naushad

    2016-02-01

    Highly crystalline zinc oxide (ZnO) nanowires (NWs) were synthesized through chemical bath deposition (CBD) method by using a simple seeding technique. The process includes dispersion of commercially available ZnO nanoparticles through spraying on a desired substrate prior to the CBD growth. A typical growth period of 16 h produced ZnO NW assemblies with an average diameter of ˜45 nm and lengths of 1-1.3 μm, with an optical band gap of ˜3.61 eV. The as-prepared ZnO NWs were photoactive under ultra violet (UV) illumination. Photodetector devices fabricated using these NW assemblies demonstrated a high photoresponse factor of ˜40 and 120 at room temperature under moderate UV illumination power of ˜250 μW/cm2. These findings indicate the possibility of using ZnO NWs, grown using the simple method discussed in this paper, for various opto-electronic applications.

  8. Sb-Doped SnO2 Nanoparticles Synthesized by Sonochemical-Assisted Precipitation Process.

    Science.gov (United States)

    Noonuruk, Russameeruk; Vittayakorn, Naratip; Mekprasart, Wanichaya; Sritharathikhun, Jaran; Pecharapa, Wisanu

    2015-03-01

    Sb-doped SnO2 nanopowders were synthesized by sonochemical-assisted precipitation process using stannic chloride pentahydrate (SnCl4.5H2O) and antimony chloride (SbC3) as starting precursors. Effect of sonication and Sb doping concentrations on physical structures and electrical properties of Sb-doped SnO2 nanoparticles were investigated by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, Raman spectroscopy and two-point probe method. The results indicated that the good dispersion with less agglomeration of particles in SnO2 phase can be obtained by single step sonochemical-assisted process. Moreover, XRD results indicated that the crystallinity of Sb-doped SnO2 nanopowders deteriorated with increasing Sb content, suggesting that Sb dopant significantly prevent SnO2 crystallite growth. The XPS spectra of Sb-doped SnO2 obviously confirmed the existence of Sb ion incorporated into SnO2 matrix. These results revealed that incorporation of Sb ions into SnO2 lattice with specific concentration has significant influence on formation and crystallization and can dramatically enhance the conductivity of tin oxide.

  9. Fivefold Enhanced Photoelectrochemical Properties of ZnO Nanowire Arrays Modified with C3N4 Quantum Dots

    Directory of Open Access Journals (Sweden)

    Hao Yang

    2017-03-01

    Full Text Available A facile and effective growing strategy of graphite-like carbon nitride quantum dots (CNQDs modified on ZnO nanowire array composite electrodes has been successfully designed and prepared for the first time. The remarkable quantum enhanced properties were carefully studied by means of scanning electron microscope (SEM, transmission electron microscopy (TEM, X-ray photoelectron spectroscope (XPS, UV-vis diffuse reflectance, PEC performance, and photocatalytic hydrogen production, and the results were in good agreement. Fivefold enhanced photoelectrochemical performances of this novel hierarchical hetero-array prepared in this paper compared with pure ZnO nanowire arrays were obtained under UV-light. The effect was attributed to the remarkable charge separation between CNQDs and ZnO nanowire arrays. Additional investigations revealed that the particular structure of CNQDs/ZnO composites contributed to the separation of a photon-generation carrier and an enhanced photoelectric current. Moreover, the absorption edge of CNQD-modified ZnO nanowire arrays was slightly broadened, and the diameter was reduced as well. The photoelectrochemistry hydrogen evolution splitting water using simulated solar irradiation exhibited the foreground of a possible application of a mechanism of photoelectrochemistry hydrogen evolution over CNQDs/ZnO composite electrodes.

  10. Efficient photocatalytic performance enhancement in Co-doped ZnO nanowires coupled with CuS nanoparticles

    Science.gov (United States)

    Li, Wei; Wang, Guojing; Feng, Yimeng; Li, Zhengcao

    2018-01-01

    In this research, a kind of highly efficient semiconductor photocatalyst was fabricated by depositing CuS nanoparticles uniformly on the surface of Co-doped ZnO nanowires. ZnO nanowires were synthesized by hydrothermal method and CuS nanoparticles were modified by successive ionic layer adsorption and reaction (SILAR). By conducting methyl orange (MO) degradation experiments under the illumination of visible light, the photocatalytic activity of Co-doped ZnO nanowires modified with CuS nanoparticles was found to be nearly three times active when compared to bare ZnO nanowires. Its superior photocatalytic performance has two main reasons. The doped Co2+ ions can inhibit the recombination of photo-generated electron-hole pairs and decrease the optical bandgap, while the p-n heterostructure can enhance the visible light absorption ability and promote the separation of photo-excited charge carriers. Furthermore, the effect of the amount of deposited CuS nanoparticles on the photocatalysis was also investigated. The photocatalytic efficiency firstly raised along with the increment of SILAR cycle times and reached a maximum at 10 cycles but then decreased as the cycle times continue to increase. This originates from that an excessive amount of CuS would not only cover the active reacting sites, but also serve as recombination centers. Overall, this new nanostructure is expected to work as an efficient photocatalyst.

  11. ZnO nanowire growth and characterization for UV detection and imaging applications

    Science.gov (United States)

    Rivera, Abdiel; Mazady, M. Anas; Zeller, John; Anwar, Mehdi; Manzur, Tariq; Sood, Ashok

    2013-06-01

    Zinc oxide (ZnO) is a unique wide bandgap biocompatible material system exhibiting both semiconducting and piezoelectric properties that has a diverse group of growth morphologies. Bulk ZnO has a bandgap of 3.37 eV that corresponds to emissions in the ultraviolet (UV) spectral band. Highly ordered vertical arrays of ZnO nanowires (NWs) have been grown on substrates including silicon, SiO2, GaN, and sapphire using a metal organic chemical vapor deposition (MOCVD) growth process. The structural and optical properties of the grown vertically aligned ZnO NW arrays were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements. Compared to conventional UV sensors, detectors based on ZnO NWs offer high UV sensitivity and low visible sensitivity, and are expected to exhibit low noise, high quantum efficiency, extended lifetimes, and have low power requirements. The photoresponse switching properties of NW array based sensing devices have been measured with intermittent exposure to UV radiation, where the devices were found to switch between low and high conductivity states at time intervals on the order of a few seconds. Furthermore, NW based UV sensors and focal plane arrays (FPAs) show promise for imaging in the near marine boundary layer, an area extending up to about six meters above the ocean surface characterized by a relatively high degree of aerosols and turbulence. Envisioned applications for such sensors/FPAs potentially integrated into submarine photonic masts (which would maintain their effectiveness even in bright daylight conditions) include threat detection and threat warning.

  12. Highly Ordered Vertical Arrays of TiO2/ZnO Hybrid Nanowires: Synthesis and Electrochemical Characterization.

    Science.gov (United States)

    Gujarati, Tanvi P; Ashish, Ajithan G; Rai, Maniratnam; Shaijumon, Manikoth M

    2015-08-01

    We report the fabrication of vertically aligned hierarchical arrays of TiO2/ZnO hybrid nanowires, consisting of ZnO nanowires grown directly from within the pores of TiO2 nanotubes, through a combination of electrochemical anodization and hydrothermal techniques. These novel nano-architectured hybrid nanowires with its unique properties show promise as high performance supercapacitor electrodes. The electrochemical behaviour of these hybrid nanowires has been studied using Cyclic voltammetry, Galvanostatic charge-discharge and Electrochemical impedance spectroscopy (EIS) measurements using 1.5 M tetraethylammoniumtetrafluoroborate in acetonitrile as the electrolyte. Excellent electrochemical performances with a maximum specific capacitance of 2.6 mF cm-2 at a current density of 10 µA cm-2, along with exceptional cyclic stability, have been obtained for TiO2/ZnO-1 h hybrid material. The obtained results demonstrate the possibility of fabricating new geometrical architectures of inorganic hybrid nanowires with well adhered interfaces for the development of hybrid energy devices.

  13. Growth of ZnO nanowires through thermal oxidation of metallic zinc films on CdTe substrates

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, O., E-mail: oscar@fmc.uva.es [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Hortelano, V.; Jimenez, J. [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Plaza, J.L.; Dios, S. de; Olvera, J.; Dieguez, E. [Laboratorio de Crecimiento de Cristales, Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Fath, R.; Lozano, J.G.; Ben, T.; Gonzalez, D. [Dpto. Ciencia de los Materiales e Ingenieria Metalurgica y Q.I., Facultad de Ciencias, Apdo. 40, 11510 Puerto Real, Cadiz (Spain); Mass, J. [Dpto. de Fisica, Universidad del Norte, Km.5 Via Puerto Colombia, Barranquilla (Colombia)

    2011-04-28

    Research highlights: > ZnO nanowires grown from thermal Zn oxidation. > TEM reveals high quality thin nanowires several microns long. > New phase formation at long oxidation time. > Good spectroscopic properties measured by Raman, Photo and Cathodoluminsecence spectroscopies. - Abstract: <112-bar 0> wurtzite ZnO nanowires (NWs) have been obtained by oxidizing in air at 500 deg. C thermally evaporated Zn metal films deposited onto CdTe substrates. The presence of Cd atoms from the substrate on the ZnO seeding layer and NWs seems to affect the growth of the NWs. The effects of the oxidation time on the structural and optical properties of the NWs are described in detail. It is shown that the NWs density decreases and their length increases when increasing the oxidation time. Thicker Zn layers result in thinner and longer ZnO NWs. Very long oxidation times also lead to the formation of a new CdO phase which is related to the partial destruction and quality reduction of the NWs. The possible process for ZnO NW formation on CdTe substrates is discussed.

  14. The effect of adsorbates on the space-charge-limited current in single ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Liao Zhimin; Lv Zhenkai; Zhou Yangbo; Yu Dapeng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Xu Jun; Zhang Jingmin [Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871 (China)], E-mail: yudp@pku.edu.cn

    2008-08-20

    We studied the influence of adsorbates on the space-charge-limited current (SCLC) in individual ZnO nanowires through varying the bias voltage, laser illumination, and ambient pressure. In dark and air conditions, the free carriers were depleted by the surface adsorbates, and electrons injected from the electrode to the nanowire dominated the electron transport properties. Under laser illumination, the current-voltage characteristic was linear at low voltage and superlinear at high voltage, and the SCLC regime occurred at high voltages due to the surface desorption. The time response of photoconductivity further revealed the dynamic process of elimination of SCLC by desorption of oxygen molecules at the ZnO nanowire surface.

  15. Physical properties of annealed ZnO nanowire/CuSCN heterojunctions for self-powered UV photodetectors.

    Science.gov (United States)

    Garnier, Jérôme; Parize, Romain; Appert, Estelle; Chaix-Pluchery, Odette; Kaminski-Cachopo, Anne; Consonni, Vincent

    2015-03-18

    The low-cost fabrication of ZnO nanowire/CuSCN heterojunctions is demonstrated by combining chemical bath deposition with impregnation techniques. The ZnO nanowire arrays are completely filled by the CuSCN layer from their bottoms to their tops. The CuSCN layer is formed of columnar grains that are strongly oriented along the [003] direction owing to the polymeric form of the β-rhombohedral crystalline phase. Importantly, an annealing step is found essential in a fairly narrow range of low temperatures, not only for outgassing the solvent from the CuSCN layer, but also for reducing the density of interfacial defects. The resulting electrical properties of annealed ZnO nanowire/CuSCN heterojunctions are strongly improved: a maximum rectification ratio of 2644 at ±2 V is achieved following annealing at 150 °C under air atmosphere, which is related to a strong decrease in the reverse current density. Interestingly, the corresponding self-powered UV photodetectors exhibit a responsivity of 0.02 A/W at zero bias and at 370 nm with a UV-to-visible (370-500 nm) rejection ratio of 100 under an irradiance of 100 mW/cm(2). The UV selectivity at 370 nm can also be readily modulated by tuning the length of ZnO nanowires. Eventually, a significant photovoltaic effect is revealed for this type of heterojunctions, leading to an open circuit voltage of 37 mV and a short circuit current density of 51 μA/cm(2), which may be useful for the self-powering of the complete device. These findings show the underlying physical mechanisms at work in ZnO nanowire/CuSCN heterojunctions and reveal their high potential as self-powered UV photodetectors.

  16. Effects of silver impurity on the structural, electrical, and optical properties of ZnO nanowires

    Directory of Open Access Journals (Sweden)

    Kim Sangsig

    2011-01-01

    Full Text Available Abstract 1, 3, and 5 wt.% silver-doped ZnO (SZO nanowires (NWs are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002 to (103 plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 106, 1.34 × 106, and 3.04 × 105 Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A0X. Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in ZnO NWs by the atomic substitution of Ag with Zn in the lattice.

  17. Contact properties and surface reaction kinetics of single ZnO nanowire devices fabricated by dielectrophoresis

    Science.gov (United States)

    Pau, J. L.; García Núñez, C.; García Marín, A.; Guerrero, C.; Rodríguez, P.; Borromeo, S.; Piqueras, J.

    2014-03-01

    This work describes the development of ZnO nanowire (NW) devices for ultraviolet detection and cost-effective gas sensing. A dielectrophoresis (DEP) flow cell fabricated for the integration of NWs on different substrates is presented. The system includes the possibility to set characteristic parameters such as alternating current (AC) frequency, amplitude or flow speed in order to control NW trapping on specific sites defined by micro-gapped electrodes. The electrical characteristics of the rectifying metal/NW contact fabricated by DEP are investigated in darkness and under direct illumination of the metal-NW interface through the ZnO NW. A significant downshift of the turn-on voltage is observed in the current-voltage characteristics during the illumination with photon energies higher than the ZnO bandgap. The reduction is attributed to a barrier height lowering induced by interface charge emission. The effects of AC bias on the thermal drift of the DC average current in NW devices are also discussed. Finally, the reaction kinetics of ethanol and water vapors on the NW surface are compared through the analysis of the DC current under direct exposure to gas flows. Device responses to more complex compound mixtures such as coffee or mint are also monitored over time, showing different performance in both cases.

  18. Nanoscale piezoelectric response of ZnO nanowires measured using a nanoindentation technique.

    Science.gov (United States)

    Broitman, Esteban; Soomro, Muhammad Yousuf; Lu, Jun; Willander, Magnus; Hultman, Lars

    2013-07-14

    We report the piezoelectric properties of ZnO nanowires (NWs) obtained by using a nanoindenter with a conductive boron-doped diamond tip. The direct piezoelectric effect was measured by performing nanoindentations under load control, and the generated piezoelectric voltage was characterized as a function of the applied loads in the range 0.2-6 mN. The converse piezoelectric effect was measured by applying a DC voltage to the sample while there was a low applied force to allow the tip being always in physical contact with the NWs. Vertically aligned ZnO NWs were grown on inexpensive, flexible, and disposable paper substrates using a template-free low temperature aqueous chemical growth method. When using the nanoindenter to measure the direct piezoelectric effect, piezopotential values of up to 26 mV were generated. Corresponding measurement of the converse piezoelectric effect gave an effective piezoelectric coefficient d33(eff) of ∼9.2 pm V(-1). The ZnO NWs were also characterized using scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy. The new nanoindentation approach provides a straightforward method to characterize piezoelectric material deposited on flexible and disposable substrates for the next generation of nanodevices.

  19. Access to residual carrier concentration in ZnO nanowires by calibrated scanning spreading resistance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L., E-mail: lin.wang@insa-lyon.fr; Brémond, G. [Institut des Nanotechnologies de Lyon (INL), Université de Lyon, CNRS UMR 5270, INSA Lyon, Bat. Blaise Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne (France); Chauveau, J. M. [Centre de Recherche sur l' Hétéro-Epitaxie et ses Applications (CRHEA), CNRS UPR10, rue Bernard Grégory 06560 Valbonne Sophia Antipolis (France); Physics Department, University of Nice Sophia Antipolis (UNS), Parc Valrose, 06103 Nice (France); Brenier, R. [Institut Lumière Matière (ILM), Université de Lyon, CNRS UMR 5306, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Sallet, V.; Jomard, F.; Sartel, C. [Groupe d' Étude de la Matière Condensée (GEMaC), CNRS-Université de Versailles St Quentin en Yvelines, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035 Versailles (France)

    2016-03-28

    Scanning spreading resistance microscopy (SSRM) was performed on non-intentionally doped (nid) ZnO nanowires (NWs) grown by metal-organic chemical vapor deposition in order to measure their residual carrier concentration. For this purpose, an SSRM calibration profile has been developed on homoepitaxial ZnO:Ga multilayer staircase structures grown by molecular beam epitaxy. The Ga density measured by SIMS varies in the 1.7 × 10{sup 17 }cm{sup −3} to 3 × 10{sup 20 }cm{sup −3} range. From measurements on such Ga doped multi-layers, a monotonic decrease in SSRM resistance with increasing Ga density was established, indicating SSRM being a well-adapted technique for two dimensional dopant/carrier profiling on ZnO at nanoscale. Finally, relevant SSRM signal contrasts were detected on nid ZnO NWs, and the residual carrier concentration is estimated in the 1–3 × 10{sup 18 }cm{sup −3} range, in agreement with the result from four-probe measurements.

  20. Two-layer ZnO nanowire arrays: Fabrication and its photovoltaic property sensitized by CdSe and CdS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Jingzhi [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Wang, Jianxiong; Sun, Xiaowei [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2015-09-01

    Two-layer ZnO nanowire arrays have been synthesized by a low temperature hydrothermal method. The two-layer structure enables the absorption of CdSe and CdS quantum dots (QDs) on different nanostructured layers, respectively. Solar cell based on the QD sensitized ZnO nanowire arrays is fabricated. Because sequential light adsorption of different sensitizers happens in two different layers, the photoanode can reduce the interaction possibility among different QDs and extend the absorption range, and result in improved photovoltaic properties. - Highlights: • Two-layer ZnO nanowire array has been synthesized by a low temperature hydrothermal. • A two-layer quantum dot sensitized ZnO nanowire array solar cell has been fabricated. • The structure can reduce interaction possibility among different quantum dots. • The structure can extend the range of light absorption.

  1. Fabrication of high performance field-effect transistors and practical Schottky contacts using hydrothermal ZnO nanowires.

    Science.gov (United States)

    Opoku, Charles; Dahiya, Abhishek Singh; Oshman, Christopher; Daumont, Christophe; Cayrel, Frederic; Poulin-Vittrant, Guylaine; Alquier, Daniel; Camara, Nicolas

    2015-09-04

    The production of large quantities of single crystalline semiconducting ZnO nanowires (NWs) at low cost can offer practical solutions to realizing several novel electronic/optoelectronic and sensor applications on an industrial scale. The present work demonstrates high-density single crystalline NWs synthesized by a multiple cycle hydrothermal process at ∼100 °C. The high carrier concentration in such ZnO NWs is greatly suppressed by a simple low cost thermal annealing step in ambient air at ∼450 °C. Single ZnO NW FETs incorporating these modified NWs are characterized, revealing strong metal work function-dependent charge transport, unobtainable with as-grown hydrothermal ZnO NWs. Single ZnO NW FETs with Al as source and drain (s/d) contacts show excellent performance metrics, including low off-state currents (fA range), high on/off ratio (10(5)-10(7)), steep subthreshold slope (V-s). Modified ZnO NWs with platinum s/d contacts demonstrate excellent Schottky transport characteristics, markedly different from a reference ZnO NW device with Al contacts. This included abrupt reverse bias current-voltage saturation characteristics and positive temperature coefficient (∼0.18 eV to 0.13 eV). This work is envisaged to benefit many areas of hydrothermal ZnO NW research, such as NW FETs, piezoelectric energy recovery, piezotronics and Schottky diodes.

  2. Digital selective growth of a ZnO nanowire array by large scale laser decomposition of zinc acetate.

    Science.gov (United States)

    Hong, Sukjoon; Yeo, Junyeob; Manorotkul, Wanit; Kang, Hyun Wook; Lee, Jinhwan; Han, Seungyong; Rho, Yoonsoo; Suh, Young Duk; Sung, Hyung Jin; Ko, Seung Hwan

    2013-05-07

    We develop a digital direct writing method for ZnO NW micro-patterned growth on a large scale by selective laser decomposition of zinc acetate. For ZnO NW growth, by replacing the bulk heating with the scanning focused laser as a fully digital local heat source, zinc acetate crystallites can be selectively activated as a ZnO seed pattern to grow ZnO nanowires locally on a larger area. Together with the selective laser sintering process of metal nanoparticles, more than 10,000 UV sensors have been demonstrated on a 4 cm × 4 cm glass substrate to develop all-solution processible, all-laser mask-less digital fabrication of electronic devices including active layer and metal electrodes without any conventional vacuum deposition, photolithographic process, premade mask, high temperature and vacuum environment.

  3. Effect of in situ Al doping on structure and optical properties of ZnO nanowires grown by MOCVD

    Science.gov (United States)

    Souissi, H.; Jabri, S.; Souissi, A.; Lusson, A.; Galtier, P.; Meftah, A.; Sallet, V.; Oueslati, M.

    2018-01-01

    Al-doped ZnO nanowires (NWs) were grown on C-axis oriented sapphire by metal organic chemical vapor deposition using dimethylzinc–triethylamine (DMZn–TEN), nitrogen dioxide (NO2) and TMAl as zinc, oxygen and aluminum doping sources respectively. The NWs morphology has been characterized by scanning electron microscopy and transmission electron microscopy. The photoluminescence (PL) spectra exhibit a strong excitonic transition bond that confirms the Al incorporation in the ZnO NWs. Raman results support PL conclusion by showing additional modes in Al-doped ZnO NWs at nearly 270, 510, 579 and 641 cm‑1. The micro-Raman scattering analysis along a single Al-doped ZnO needle-like NW shows an increase of the Al concentration from the basis to the tip of the wire.

  4. Controlled fabrication and selective CVD growth of ZnO Nanowires and Nanoribbons enabled by Direct Write parallel patterning technique

    Science.gov (United States)

    Alameri, Dheyaa; Schurz, Robert; Ocola, Leonidas E.; Liu, Yuzi; Kuljanishvili, Irma

    We present a new approach for controllable synthesis of ZnO nanowires and nanoribbons by employing a `direct write' patterning and subsequent Chemical Vapor Deposition (CVD) methods. In this work we implemented our developed precursor `ink' as catalyst, and demonstrated the growth of high quality ZnO nanostructures prepared in various geometric architectures; nanoflowers, nanoribbons, and more complex shapes. We employ multi-pen AFM cantilevers for parallel writing of the precursor ink to create arrays of patterns (dots, lines) over the large areas on the substrates. We show that the diameter and the length of the grown nanowires can be controlled by the `ink' composition, geometry of the patterns written on the substrate and the growth conditions during the synthesis. Here we show that the individual nanowires can range from (100- 250) nm in diameter , and 1 μm to 3 μm in length. We also demonstrate that various design patterns can be easily created on different substrates such as Si/SiO2 or graphene, and directly on prefabricated devices. Arrays of ZnO nanowires and nanoribbons were characterized by Raman , X-ray photoelectron and Photoluminescence spectroscopies. I/V characteristics of devices will also be discussed. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02 06CH11357.

  5. Optical and Electrical Investigation of ZnO Nano-Wire Array to Micro-Flower from Hierarchical Nano-Rose Structures

    NARCIS (Netherlands)

    Pal, Kaushik; Zhan, Bihong; Ma, Xiao; Wang, Guoping; Schirhagl, Romana; Murgasen, Priya

    We have demonstrated a simple solvo-chemical and solvo-thermal route to design various nano structures growth of zinc oxide (ZnO). The shapes and morphologies can be easily controlled by using different ambient conditions. We successfully fabricated ZnO nano-wires array on ITO substrate. Those

  6. Direct observation of Li diffusion in Li-doped ZnO nanowires

    Science.gov (United States)

    Li, Guohua; Yu, Lei; Hudak, Bethany M.; Chang, Yao-Jen; Baek, Hyeonjun; Sundararajan, Abhishek; Strachan, Douglas R.; Yi, Gyu-Chul; Guiton, Beth S.

    2016-05-01

    The direct observation of Li diffusion in Li-doped zinc oxide nanowires (NWs) was realized by using in situ heating in the scanning transmission electron microscope (STEM). A continuous increase of low atomic mass regions within a single NW was observed between 200 °C and 600 °C when heated in vacuum, which was explained by the conversion of interstitial to substitutional Li in the ZnO NW host lattice. A kick-out mechanism is introduced to explain the migration and conversion of the interstitial Li (Lii) to Zn-site substitutional Li (LiZn), and this mechanism is verified with low-temperature (11 K) photoluminescence measurements on as-grown and annealed Li-doped zinc oxide NWs, as well as the observation of an increase of NW surface roughing with applied bias.

  7. Input/output pulse operation of ZnO nanowire threshold integrators

    Energy Technology Data Exchange (ETDEWEB)

    White, Richard; Colli, Alan; Li Hongwei; Kivioja, Jani, E-mail: alan.colli@nokia.com [Nokia Research Center, Broers Building, 21 J J Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2011-01-14

    Integrating more functionality into individual nano-components is a key step to exploit alternative architectures for energy-efficient computation, such as, for instance, neuromorphic computing. Here, we show how to configure ZnO nanowire field-effect transistors as light pulse integrators with programmable threshold. We demonstrate that these single-component devices can be operated as both synchronous and asynchronous neuron-like structures, where the firing threshold and the form of the output signal, either step-like or spiked, can be controlled by using several operational parameters, including the environment in which the device operates. A detailed study showing how environmental variables, such as relative humidity, ambient light and temperature, affect device operation is presented.

  8. Room temperature strong coupling effects from single ZnO nanowire microcavity

    KAUST Repository

    Das, Ayan

    2012-05-01

    Strong coupling effects in a dielectric microcavity with a single ZnO nanowire embedded in it have been investigated at room temperature. A large Rabi splitting of ?100 meV is obtained from the polariton dispersion and a non-linearity in the polariton emission characteristics is observed at room temperature with a low threshold of 1.63 ?J/cm2, which corresponds to a polariton density an order of magnitude smaller than that for the Mott transition. The momentum distribution of the lower polaritons shows evidence of dynamic condensation and the absence of a relaxation bottleneck. The polariton relaxation dynamics were investigated by timeresolved measurements, which showed a progressive decrease in the polariton relaxation time with increase in polariton density. © 2012 Optical Society of America.

  9. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Science.gov (United States)

    Demes, Thomas; Ternon, Céline; Morisot, Fanny; Riassetto, David; Legallais, Maxime; Roussel, Hervé; Langlet, Michel

    2017-07-01

    Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20-25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20-25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  10. Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

    Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

  11. Synthesis of high crystallinity ZnO nanowire array on polymer substrate and flexible fiber-based sensor.

    Science.gov (United States)

    Liu, Jinmei; Wu, Weiwei; Bai, Suo; Qin, Yong

    2011-11-01

    Well aligned ZnO nanowire (NW) arrays are grown on Kevlar fiber and Kapton film via the chemical vapor deposition (CVD) method. These NWs have better crystallinity than those synthesized through the low-temperature hydrothermal method. The average length and diameter of ZnO NWs grown on Kevlar fiber can be controlled from 0.5 to 2.76 μm and 30 to 300 nm, respectively. A flexible ultraviolet (UV) sensor based on Kevlar fiber/ZnO NWs hybrid structure is made to detect UV illumination quantificationally.

  12. Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

    2017-01-30

    The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscaleengineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol–gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscaleengineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

  13. Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

    Science.gov (United States)

    Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

    2017-03-01

    The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscale-engineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol-gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscale-engineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

  14. Electric-field control of ferromagnetism in Mn-doped ZnO nanowires.

    Science.gov (United States)

    Chang, Li-Te; Wang, Chiu-Yen; Tang, Jianshi; Nie, Tianxiao; Jiang, Wanjun; Chu, Chia-Pu; Arafin, Shamsul; He, Liang; Afsal, Manekkathodi; Chen, Lih-Juann; Wang, Kang L

    2014-01-01

    In this Letter, the electric-field control of ferromagnetism was demonstrated in a back-gated Mn-doped ZnO (Mn-ZnO) nanowire (NW) field-effect transistor (FET). The ZnO NWs were synthesized by a thermal evaporation method, and the Mn doping of 1 atom % was subsequently carried out in a MBE system using a gas-phase surface diffusion process. Detailed structural analysis confirmed the single crystallinity of Mn-ZnO NWs and excluded the presence of any precipitates or secondary phases. For the transistor, the field-effect mobility and n-type carrier concentration were estimated to be 0.65 cm(2)/V·s and 6.82 × 10(18) cm(-3), respectively. The magnetic hysteresis curves measured under different temperatures (T = 10-350 K) clearly demonstrate the presence of ferromagnetism above room temperature. It suggests that the effect of quantum confinements in NWs improves Tc, and meanwhile minimizes crystalline defects. The magnetoresistace (MR) of a single Mn-ZnO NW was observed up to 50 K. Most importantly, the gate modulation of the MR ratio was up to 2.5 % at 1.9 K, which implies the electric-field control of ferromagnetism in a single Mn-ZnO NW.

  15. Investigation of novel heterojunction: P-type SnS coated n-type ZnO nanowire

    Science.gov (United States)

    Bu, Ian Y. Y.

    2015-12-01

    SnS coated ZnO nanowires heterojunctional solar cells were fabricated using a combination of hydrothermal synthesis and chemical bath deposition (CBD) method. The synthesized materials and devices were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), photoluminescence emission spectroscopy, Uv-Vis spectroscopy and electrical measurements. SEM imaging of the sample revealed that the CBD SnS coating bunches the underlying ZnO nanowires due to the large capillary force it experiences during the drying process. Both of the EDS and XRD measurements confirm the presence of SnS and SnO2. Optoelectronic measurement confirms that the fabricated device exhibit high absorbance (∼80%) and exhibit photovoltaic behaviour.

  16. Tunable local excitation of surface plasmon polaritons by sum-frequency generation in ZnO nanowires

    Science.gov (United States)

    Brincker, Mads; Pedersen, Kjeld; Skovsen, Esben

    2015-12-01

    Tunable local excitation of surface plasmon polaritons (SPP) by sum-frequency generation (SFG) in Zinc Oxide (ZnO) nanowires on a smooth and thin silver film has been studied by applying angle resolved leakage radiation spectroscopy. SFG between an infrared (IR) source, with a variable wavelength in the telecom range between 1350 nm and 1550 nm, and a near-infrared (NIR) source with a fixed wavelength of 790 nm resulted in the excitation of SPP's at wavelengths between 498 nm and 523 nm. The SFG to SPP coupling efficiency was studied as a function of the excitation angle and the wavelength of the IR source. It was shown that the SPP coupling was most efficient at oblique excitation angles, and that SFG in ZnO nanowires allows for the coherent conversion of optical signals at telecom frequencies to SPP's with frequencies within the visible range.

  17. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    KAUST Repository

    Lin, S S

    2009-08-18

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS. © 2009 IOP Publishing Ltd.

  18. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S S; Song, J H; Wang, Z L [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Lu, Y F, E-mail: zlwang@gatech.ed [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China)

    2009-09-09

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS.

  19. ZnO Nanowire Formation by Two-Step Deposition Method Using Energy-Controlled Hollow-Type Magnetron RF Plasma

    Directory of Open Access Journals (Sweden)

    Hideki Ono

    2011-01-01

    Full Text Available ZnO nanowire was produced in RF (radio frequency discharge plasma. We employed here a two-step deposition technique. In the 1st step, zinc atoms were sputtered from a zinc target to create zinc nuclei on a substrate before the growth of ZnO nanostructure. Here, we used pure argon plasma for physical sputtering. In the 2nd step, we employed an oxygen discharge mixed with argon, where oxygen radicals reacted with zinc nuclei to form ZnO nanostructures. Experimental parameters such as gas flow ratio and target bias voltage were controlled in O2/Ar plasma. Properties of the depositions were analysed by SEM and Raman spectroscopy. We found that many folded and bundled nanowires formed in the 2nd step. The diameter of wires was typically 10–100 nm. We also discussed a growth mechanism of ZnO nanowires.

  20. Epitaxial growth of ZnO Nanodisks with large exposed polar facets on nanowire arrays for promoting photoelectrochemical water splitting.

    Science.gov (United States)

    Chen, Haining; Wei, Zhanhua; Yan, Keyou; Bai, Yang; Zhu, Zonglong; Zhang, Teng; Yang, Shihe

    2014-11-01

    Single-crystalline and branched 1D arrays, ZnO nanowires/nanodisks (NWs/NDs) arrays, are fabricated to significantly enhance the performance of photoelectrochemical (PEC) water splitting. The epitaxial growth of the ZnO NDs with large exposed polar facets on ZnO NWs exhibits a laminated structure, which dramatically increases the light scattering capacity of the NWs arrays, especially in the wavelength region around 400 nm. The ND branching of the 1D arrays in the epitaxial fashion not only increase surface area and light utilization, but also support fast charge transport, leading to the considerable increase of photocurrent. Moreover, the tiny size NDs can facilitate charge separation and reduce charge recombination, while the large exposed polar facets of NDs reduce the external potential bias needed for water splitting. These advantages land the ZnO NWs/NDs arrays a four times higher power conversion efficiency than the ZnO NWs arrays. By sensitizing the ZnO NWs/NDs with CdS and CdSe quantum dots, the PEC performance can be further improved. This work advocates a trunk/leaf in forest concept for the single-crystalline NWs/NDs in array with enlarged exposure of polar facets, which opens the way for optimizing light harvesting and charge separation and transport, and thus the PEC water splitting. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Silver nanowires network encapsulated by low temperature sol–gel ZnO for transparent flexible electrodes with ambient stability

    Science.gov (United States)

    Shin, Wonjung; Cho, Wonki; Baik, Seung Jae

    2018-01-01

    As a geometrically engineered realization of transparent electrode, Ag nanowires network is promising for its superior characteristics both on electrical conductivity and optical transmittance. However, for a potential commercialization of Ag nanowires network, further investigations on encapsulation materials are necessary to prevent degradation caused by ambient aging. In addition, the temperature range of the coating process for the encapsulation material needs to be low enough to prevent degradation of polymer substrates during the film coating processes, when considering emerging flexible device application of transparent electrodes. We present experimental results showing that low temperature sol–gel ZnO processed under 130 °C is an effective encapsulation material preventing ambient oxidation of Ag nanowires network without degrading electrical, optical, and mechanical properties.

  2. Enhanced non-volatile resistive switching in suspended single-crystalline ZnO nanowire with controllable multiple states

    Science.gov (United States)

    Zhang, Rui; Pang, Wei; Zhang, Qing; Chen, Yan; Chen, Xuejiao; Feng, Zhihong; Yang, Jianhua; Zhang, Daihua

    2016-08-01

    Resistive switching nanostructures are a promising candidate for next-generation non-volatile memories. In this report, we investigate the switching behaviors of single-crystalline ZnO nanowires suspended in air. They exhibit significantly higher current density, lower switching voltage, and more pronounced multiple conductance states compared to nanowires in direct contact with substrate. We attribute the effect to enhanced Joule heating efficiency, reduced surface scattering, and more significantly, the positive feedback established between the current density and local temperature in the suspended nanowires. The proposed mechanism has been quantitatively examined by finite element simulations. We have also demonstrated an innovative approach to initiating the current-temperature mutual enhancement through illumination by ultraviolet light, which further confirmed our hypothesis and enabled even greater enhancement. Our work provides further insight into the resistive switching mechanism of single-crystalline one-dimensional nanostructures, and suggests an effective means of performance enhancement and device optimization.

  3. Synthesis of Ni(OH)2 nanoflakes on ZnO nanowires by pulse electrodeposition for high-performance supercapacitors

    Science.gov (United States)

    Lo, I.-Hsiang; Wang, Jun-Yi; Huang, Kuo-Yen; Huang, Jin-Hua; Kang, Weng P.

    2016-03-01

    A high-performance supercapacitor based on Ni(OH)2 nanoflakes modified ZnO nanowires (NWs) was developed. The well-aligned ZnO NWs were synthesized by chemical bath deposition, followed by pulse electrodeposition of Ni(OH)2 nanoflakes on the surface of ZnO NWs at 1 mA cm-2 current density. The effects of the pulse electrodeposition conditions were systematically investigated. Both the pulse time and relaxation time were found to affect the size and interspacing of the nanoflakes, while the deposition cycle number determines the thickness of the Ni(OH)2 nanoflake shell. The ZnO/Ni(OH)2 nanocomposite electrode fabricated under the optimal pulse electrodeposition conditions has exhibited a large specific capacitance of 1830 F g-1, a high energy density of 51.5 Wh kg-1, and a high power density of 9 kW kg-1, revealing its potential application in electrochemical capacitors.

  4. Earth-abundant oxygen evolution catalysts coupled onto ZnO nanowire arrays for efficient photoelectrochemical water cleavage.

    Science.gov (United States)

    Jiang, Chaoran; Moniz, Savio J A; Khraisheh, Majeda; Tang, Junwang

    2014-09-26

    ZnO has long been considered as a model UV-driven photoanode for photoelectrochemical water splitting, but its performance has been limited by fast charge-carrier recombination, extremely poor stability in aqueous solution, and slow kinetics of water oxidation. These issues were addressed by applying a strategy of optimization and passivation of hydrothermally grown 1D ZnO nanowire arrays. The length and diameter of bare ZnO nanowires were optimized by varying the growth time and precursor concentration to achieve optimal photoelectrochemical performance. The addition of earth-abundant cobalt phosphate (Co-Pi) and nickel borate (Ni-B) oxygen evolution catalysts onto ZnO nanowires resulted in substantial cathodic shifts in onset potential to as low as about 0.3 V versus the reversible hydrogen electrode (RHE) for Ni-B/ZnO, for which a maximum photocurrent density of 1.1 mA cm(-2) at 0.9 V (vs. RHE) with applied bias photon-to-current efficiency of 0.4 % and an unprecedented near-unity incident photon-to-current efficiency at 370 nm. In addition the potential required for saturated photocurrent was dramatically reduced from 1.6 to 0.9 V versus RHE. Furthermore, the stability of these ZnO nanowires was significantly enhanced by using Ni-B compared to Co-Pi due to its superior chemical robustness, and it thus has additional functionality as a stable protecting layer on the ZnO surface. These remarkable enhancements in both photocatalytic activity and stability directly address the current severe limitations in the use of ZnO-based photoelectrodes for water-splitting applications, and can be applied to other photoanodes for efficient solar-driven fuel synthesis. © 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  5. Piezo and photoelectric coupled nanogenerator using CdSe quantum dots incorporated ZnO nanowires in ITO/ZnO NW/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Kathalingam, A.; Valanarasu, S.; Senthilkumar, V. [Millimeter-wave INnovation Technology Research Center (MINT), Dongguk University, Seoul 100-715 (Korea, Republic of); Rhee, Jin-Koo, E-mail: jkrhee@dongguk.edu [Millimeter-wave INnovation Technology Research Center (MINT), Dongguk University, Seoul 100-715 (Korea, Republic of)

    2013-02-15

    We report the fabrication of ITO/n-ZnO NW/p-Si sandwiched structure and its photoelectric and piezoelectric conversion properties. This hybrid cell was designed to harvest simultaneously both solar and mechanical energies. ZnO nanowires used in the work were grown on p-type Si substrates employing seed mediated low-temperature aqueous solution method. The synthesized ZnO nanowires were characterized by XRD, SEM and EDX characterization for their structural and morphological evaluation. The as-grown ZnO nanowires showed good crystallinity with c-axis preferable orientation. Free ZnO nanowires and CdSe quantum dots were also incorporated with the vertically grown nanowires and their response in harvesting optical and mechanical energies were investigated. The piezoelectric and photoelectric coupled effects of a ZnO nanowire device in the simultaneous conversion of both optical and mechanical energies have been studied for the first time with the goal of designing piezoelectric and photoelectric hybrid nanogenerator. This presented ITO/n-ZnO NW/p-Si heterojunction architecture is envisaged as a potentially valuable candidate for the next generation energy harvesting devices. Graphene-coated ITO was also used and its response was studied. - Highlights: ► Fabricated an unique sandwich type ITO/n-ZnO NW/p-Si nanogenerator. ► Simultaneous harvesting of both light and mechanical energy achieved. ► CdSe incorporation with ZnO nanowires increased the performance of the device. ► First report integrated both nanogenerator and solar cell in a same surface. ► Incorporating nanoantenna this structure can harvest light, heat and sound.

  6. Effect of exposure time on the growth of self-supporting ZnO nanowire arrays and their photocatalytic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiao; Zeng, Xiangyun; Yang, Wanli; Gao, Meizhen, E-mail: gaomz@lzu.edu.cn

    2015-01-15

    Highlights: • Self-supporting ZnO NWAs were successfully fabricated by hydrothermal process. • We studied the effect of the exposure time on the structure of NWAs. • The photocatalytic activity and durability were studied. • Finally, an optimized growth condition was proposed. - Abstract: We have successfully fabricated self-supporting ZnO nanowire arrays (NWAs) by recently proposed versatile hydrothermal process. The effect of exposure time on microstructure and photocatalytic performance of ZnO NWAs has been analyzed for the first time, which is the main finding of the present work. Specifically, with increasing exposure time, the vertical alignment is improved and the diameter of NWAs is decreased. Under 15 min exposure time, the obtained ZnO NWAs exhibit the most uniform, dense, and thin arrays. SEM images show that all the NWAs are about 200–300 nm in diameter and 9 μm in length. Furthermore, photocatalytic tests indicated that the as-prepared ZnO NWAs exposed with 15 min exhibited the best activity for photo-degradation of organic dye under UV light irradiation. After 5 recycles, the sample did not exhibit an obvious loss in activity, confirming its good activity upon recycling.

  7. Synthesis, surface modification and ethanol sensing properties of Sb-doped SnO2

    Science.gov (United States)

    Huang, Jiarui; Yu, Kun; Zhukova, Anna A.; Rumyantseva, Marina N.; Gaskov, Alexandre M.; Wang, Junhai; Gu, Cuiping; Liu, Jinhuai

    2009-07-01

    Sb-doped SnO2 whiskers were prepared by thermal evaporation of mixture of SnO and Sb2O3 powders. And then the surface of the whisker was modified with the Au nanoparticles (Au NPs) by in situ reduction method. FE-SEM observations reveal that the synthesized products consist of a large number of whiskers. The Au NPs were homogeneously distributed on the surface of the whisker. The ethanol sensitive characteristics of single SnO2 whiskerbased sensors have been investigated. These sensors show good sensitivity, rapid response and recovery. The response and recovery time of the sensor is about 38-45 s and 125-150 s, respectively. It is found that the working temperature of the sensor decreases after the surface of Sb-doped whiskers modified with Au NPs. Compared to the unmodified Sbdoped SnO2 whisker, Au NPs modified Sb-doped SnO2 whisker exhibits greatly improvement of sensitivity which could be explained by the catalytic action of Au NPs. These results indicate that the Au NPs modifying the surface of SnO2 whiskers is important for improving its sensitivity and lowering the working temperature. This is the first step towards fundamental understanding of single-crystalline tin oxide whiskers for sensor applications, which could lead to integration in real devices.

  8. Heteroepitaxial Patterned Growth of Vertically Aligned and Periodically Distributed ZnO Nanowires on GaN Using Laser Interference Ablation

    KAUST Repository

    Yuan, Dajun

    2010-08-23

    A simple two-step method of fabricating vertically aligned and periodically distributed ZnO nanowires on gallium nitride (GaN) substrates is described. The method combines laser interference ablation (LIA) and low temperature hydrothermal decomposition. The ZnO nanowires grow heteroepitaxially on unablated regions of GaN over areas spanning 1 cm2, with a high degree of control over size, orientation, uniformity, and periodicity. High resolution transmission electron microscopy and scanning electron microscopy are utilized to study the structural characteristics of the LIA-patterned GaN substrate in detail. These studies reveal the possible mechanism for the preferential, site-selective growth of the ZnO nanowires. The method demonstrates high application potential for wafer-scale integration into sensor arrays, piezoelectric devices, and optoelectronic devices. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Modeling and characterization of extremely thin absorber (eta) solar cells based on ZnO nanowires.

    Science.gov (United States)

    Mora-Seró, Iván; Giménez, Sixto; Fabregat-Santiago, Francisco; Azaceta, Eneko; Tena-Zaera, Ramón; Bisquert, Juan

    2011-04-21

    Extremely thin absorber (eta)-solar cells based on ZnO nanowires sensitized with a thin layer of CdSe have been prepared, using CuSCN as hole transporting material. Samples with significantly different photovoltaic performance have been analyzed and a general model of their behavior was obtained. We have used impedance spectroscopy to model the device discriminating the series resistance, the role of the hole conducting material CuSCN, and the interface process. Correlating the impedance analysis with the microstructural properties of the solar cell interfaces, a good description of the solar cell performance is obtained. The use of thick CdSe layers leads to high recombination resistances, increasing the open circuit voltage of the devices. However, there is an increase of the internal recombination in thick light absorbing layers that also inhibit a good penetration of CuSCN, reducing the photocurrent. The model will play an important role on the optimization of these devices. This analysis could have important implications for the modeling and optimization of all-solid devices using a sensitizing configuration.

  10. Electrodeposited ZnO nanowires as photoelectrodes in solid-state organic dye-sensitized solar cells.

    Science.gov (United States)

    Muguerra, Hervé; Berthoux, Gaëlle; Yahya, Wan Zaireen Nisa; Kervella, Yann; Ivanova, Valentina; Bouclé, Johann; Demadrille, Renaud

    2014-04-28

    A new approach for developing solid-state dye-sensitised solar cells (DSSCs) on glass/ITO and plastic substrates (PEN/ITO) is presented in this manuscript. A two step electrodeposition technique has been employed to realize the ZnO photoelectrodes. First a ZnO thin film is deposited on the ITO substrate and subsequently on this buffer layer 650 nm long ZnO nanowires are grown. The different nanostructured electrodes are crystallized and show a transparency close to 80% in the visible spectral range. The electrodes are then sensitized with a new purely organic dye, whose synthesis is presented here, which reveals a wide absorption spectrum and a high molar extinction coefficient. Finally, the sensitized electrodes were employed for the fabrication of liquid and solid-state DSSCs, using, respectively, a liquid iodine/iodide electrolyte and the spiro-OMeTAD hole transporter. These devices represent the first solid-state DSSCs fabricated using electrodeposited zinc oxide nanowires. Their power conversion efficiency is still limited, respectively, 0.18% and 0.03% under standard AM 1.5G sunlight (100 mW cm(-2)), nevertheless, these results prove the interest in this low-temperature deposition method for the realization of nanostructured electrodes on rigid and flexible substrates, and open up new perspectives for the development of solid state DSSCs on plastic substrates.

  11. ZnO dense nanowire array on a film structure in a single crystal domain texture for optical and photoelectrochemical applications

    Science.gov (United States)

    Zhong, Miao; Sato, Yukio; Kurniawan, Mario; Apostoluk, Aleksandra; Masenelli, Bruno; Maeda, Etsuo; Ikuhara, Yuichi; Delaunay, Jean-Jacques

    2012-12-01

    A single crystal domain texture quality (a unique in-plane and out-of-plane crystalline orientation over a large area) ZnO nanostructure of a dense nanowire array on a thick film has been homogeneously synthesized on a-plane sapphire substrates over large areas through a one-step chemical vapor deposition (CVD) process. The growth mechanism is clarified: a single crystal [0\\bar {2}1] oriented ZnAl2O4 buffer layer was formed at the ZnO film and the a-plane sapphire substrate interface via a diffusion reaction process during the CVD process, providing improved epitaxial conditions that enable the synthesis of the high crystalline quality ZnO nanowire array on a film structure. The high optoelectronic quality of the ZnO nanowire array on a film sample is evidenced by the free exitonic emissions in the low-temperature photoluminescence spectroscopy. A carrier density of ˜1017 cm-3 with an n-type conductivity of the ZnO nanowire array on a film sample is obtained by electrochemical impedance analysis. Finally, the ZnO nanowire array on a film sample is demonstrated to be an ideal template for a further synthesis of a single crystal quality ZnO-ZnGa2O4 core-shell nanowire array on a film structure. The fabricated ZnO-ZnGa2O4 sample revealed an enhanced anticorrosive ability and photoelectrochemical performance when used as a photoanode in a photoelectrochemical water splitting application.

  12. Use of the Thermal Chemical Vapor Deposition to Fabricate Light-Emitting Diodes Based on ZnO Nanowire/p-GaN Heterojunction

    Directory of Open Access Journals (Sweden)

    Sheng-Po Chang

    2011-01-01

    Full Text Available The fabrication and characteristics of grown ZnO nanowire/p-GaN heterojunction light-emitting diodes are reported. Vertically aligned ZnO nanowire arrays were grown on a p-GaN substrate by thermal chemical vapor deposition in quartz tube. The rectifying current-voltage characteristics indicate that a p-n junction was formed with a heterostructure of n-ZnO nanowire/p-GaN. The room temperature electroluminescent emission peak at 425 nm was attributed to the band offset at the interface between the n-ZnO nanowire and p-GaN and to defect-related emission from GaN; it was also found that the there exist the yellow band in the hetrojunction. It would be attributed to the deep defect level in the heterojunction.

  13. Self-Organized Growth of Two-Dimensional GaTe Nanosheet on ZnO Nanowires for Heterojunctional Water Splitting Applications.

    Science.gov (United States)

    Li, Qiuguo; Ma, Xinzhou; Liu, Huiqiang; Chen, Zuxin; Chen, Hao; Chu, Sheng

    2017-06-07

    Epitaxial two-dimensional GaTe nanosheets on ZnO nanowires were routinely prepared via a two-step chemical vapor deposition procedure. The epitaxial relationship and growth mechanism of the GaTe/ZnO core/shell structures were explored and attributed to a layer-overlayer model. The hybrid structures increased the surface area and the favorable p-n heterojunction enhanced the charge separation for photoelectrochemical performance in water splitting. The above synergistic effects boosted the photocurrent density from -0.3 mA cm-2 for the pristine ZnO nanowires to -2.5 mA cm-2 for the core/shell GaTe/ZnO nanowires at -0.39 V vs RHE under the visible light irradiation. This highlights the promise for utilization of GaTe nanosheet/ZnO nanowires as efficient photoelectrocatalyst for water splitting.

  14. An Enhanced UV-Vis-NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure.

    Science.gov (United States)

    Zheng, Zhi; Gan, Lin; Zhang, Jianbing; Zhuge, Fuwei; Zhai, Tianyou

    2017-03-01

    ZnO nanostructure-based photodetectors have a wide applications in many aspects, however, the response range of which are mainly restricted in the UV region dictated by its bandgap. Herein, UV-vis-NIR sensitive ZnO photodetectors consisting of ZnO nanowires (NW) array/PbS quantum dots (QDs) heterostructures are fabricated through modified electrospining method and an exchanging process. Besides wider response region compared to pure ZnO NWs based photodetectors, the heterostructures based photodetectors have faster response and recovery speed in UV range. Moreover, such photodetectors demonstrate good flexibility as well, which maintain almost constant performances under extreme (up to 180°) and repeat (up to 200 cycles) bending conditions in UV-vis-NIR range. Finally, this strategy is further verified on other kinds of 1D nanowires and 0D QDs, and similar enhancement on the performance of corresponding photodetecetors can be acquired, evidencing the universality of this strategy.

  15. The assessment for sensitivity of a NO2 gas sensor with ZnGa2O4/ZnO core-shell nanowires--a novel approach.

    Science.gov (United States)

    Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Hsu, Cheng-Liang; Hsueh, Ting Jen; Shieh, Tien-Yu

    2010-01-01

    The application of novel core-shell nanowires composed of ZnGa2O4/ZnO to improve the sensitivity of NO2 gas sensors is demonstrated in this study. The growth of ZnGa2O4/ZnO core-shell nanowires is performed by reactive evaporation on patterned ZnO:Ga/SiO2/Si templates at 600 °C. This is to form the homogeneous structure of the sensors investigated in this report to assess their sensitivity in terms of NO2 detection. These novel NO2 gas sensors were evaluated at working temperatures of 25 °C and at 250 °C, respectively. The result reveals the ZnGa2O4/ZnO core-shell nanowires present a good linear relationship (R2>0.99) between sensitivity and NO2 concentration at both working temperatures. These core-shell nanowire sensors also possess the highest response (ZnGa2O4/ZnO core-shell nanowire based sensors are highly promising for industrial applications.

  16. Effects of ZnS layer on the performance improvement of the photosensitive ZnO nanowire arrays solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Javed, Hafiz Muhammad Asif [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, Xi' an Jiaotong University, Xi' an, 710049 (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, Xi' an Jiaotong University, Xi' an, 710049 (China); Gao, Yanping; Xing, Yonglei [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, Xi' an Jiaotong University, Xi' an, 710049 (China); Kong, Ling Bing, E-mail: ELBKong@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, 639798 (Singapore)

    2016-08-01

    The impact of ZnS layer as an interface modification on the photosensitive ZnO nanowire arrays solar cells was studied. CdS, CdSe and ZnS were deposited on ZnO nanowire arrays by SILAR method. When a ZnS layer was deposited, the quantum dot barrier was indirectly become in contact with the electrolyte, which thus restrained the flow of electrons. The CdS sensitized solar cells has an efficiency of 0.55% with the deposition of the ZnS(3) layer, that is, with a deposition of three times, whereas the CdS/CdSe co-sensitized solar cells has an efficiency of 2.03% with the deposition of the ZnS(1) layer. It was also noted that as the thickness of the of ZnS layer was increased, V{sub oc}, I{sub sc} and efficiencies of both the solar cells were first increased and then decreased. In addition, the CdS/N719 solar cells has an efficiency of 0.75% with the deposition of the ZnS(2) layer. - Highlights: • The impact of ZnS layer on the photosensitive ZnO nanowire solar cells was studied. • ZnS layer restrained the flow of electrons to the electrolyte. • CdS/CdSe co-sensitized solar cells have higher efficiency than CdS solar cells. • When ZnS layer was increased, V{sub oc} and I{sub sc} firstly increased and then decreased.

  17. Defect formation and magnetic properties of carbon-doped ZnO nanowires by the first principles

    Science.gov (United States)

    Shi, Li-Bin; Li, Ming-Biao; Fei, Ying

    2013-02-01

    Theoretical calculation based on density functional theory (DFT) and local density approximation (LDA) with Hubbard parameters has been carried out in studying defect formation energy, transition energy and ferromagnetism of carbon-doped ZnO nanowires (NW). The formation and ionization characteristics of the defects [CO (B), CO (S), CZn (B), VO (B), VZn (B), IO (oct) and IZn (oct)] in ZnO NW are analyzed in the text. Ferromagnetic (FM) and antiferromagnetic (AFM) coupling between C atoms are also investigated by 9 different configurations. The FM and AFM stability are explained by the interaction of C energy level. In addition, the vacancies [VO (B) and VZn (B)] and interstitials [IO (oct) and IZn (oct)] affecting the FM coupling are also investigated. It is found that magnetic moment of C 2p can be mediated by these defects.

  18. Physically processed Ag-doped ZnO nanowires for all-ZnO p-n diodes.

    Science.gov (United States)

    Song, Yong-Won; Kim, Kyoungwon; Ahn, Jae Pyoung; Jang, Gun-Eik; Lee, Sang Yeol

    2009-07-08

    We synthesize and analyze Ag-doped ZnO (SZO) nanowires (NWs) via a vapor-liquid-solid mechanism in a physical vapor deposition. The process condition for the SZO NW formation is optimized by adjusting the kinetic energy and the flux of the laser-ablated particles by hot-wall control. Electron microscopes ensure excellent morphologies of the doped NWs obtained. We confirm p-type doping effects, with low temperature photoluminescence used to trace the A(0)X peak. We realize diodes with all-ZnO-based p-n junctions of SZO NWs and Ga-doped ZnO thin films, resulting in asymmetric I-V characteristics with the turn on voltage of 3.8 V.

  19. Photoelectric probing of the interfacial trap density-of-states in ZnO nanowire field-effect transistors.

    Science.gov (United States)

    Raza, Syed Raza Ali; Lee, Young Tack; Chang, Youn-Gyoung; Jeon, Pyo Jin; Kim, Jae Hoon; Ha, Ryong; Choi, Heon-Jin; Im, Seongil

    2013-02-28

    We have fabricated transparent top-gate ZnO nanowire (NW) field effect transistors (FETs) on glass and measured their trap density-of-states (DOS) at the dielectric/ZnO NW interface with monochromatic photon beams during their operation. Our photon-probe method showed clear signatures of charge trap DOS at the interface, located near 2.3, 2.7, and 2.9 eV below the conduction band edge. The DOS information was utilized for the photo-detecting application of our transparent NW-FETs, which demonstrated fast and sensitive photo-detection of visible lights.

  20. Europium doping induced symmetry deviation and its impact on the second harmonic generation of doped ZnO nanowires

    Science.gov (United States)

    Dhara, Soumen; Imakita, Kenji; Mizuhata, Minoru; Fujii, Minoru

    2014-06-01

    In this work, we investigated the effects of europium doping on the second harmonic generation (SHG) of ZnO nanowires (NWs). A non-monotonic enhancement in the SHG is observed with the increase of the europium concentration. Maximum SHG is observed from the 1 at.% europium doped ZnO NWs with an enhancement factor of 4.5. To understand the underlying mechanism, the effective second order non-linear coefficient (deff) is calculated from the theoretical fitting with consideration of the absorption effect. Microstructural characterization reveals the structural deformation of the ZnO NWs caused by europium doping. We estimated the deviation in the crystal site symmetry around the Eu3+ ions (defined as the asymmetric factor) from photoluminescence measurement and it is found to be strongly correlated with the calculated deff value. A strong linear dependence between the magnitudes of deff and the asymmetric factor suggests that deviation in the local site symmetry of the ZnO crystal by europium doping could be the most probable origin of the observed large second order non-linearity.

  1. Chlorine Gas Sensing Performance of On-Chip Grown ZnO, WO3, and SnO2 Nanowire Sensors.

    Science.gov (United States)

    Tran, Van Dang; Nguyen, Duc Hoa; Nguyen, Van Duy; Nguyen, Van Hieu

    2016-02-01

    Monitoring toxic chlorine (Cl2) at the parts-per-billion (ppb) level is crucial for safe usage of this gas. Herein, ZnO, WO3, and SnO2 nanowire sensors were fabricated using an on-chip growth technique with chemical vapor deposition. The Cl2 gas-sensing characteristics of the fabricated sensors were systematically investigated. Results demonstrated that SnO2 nanowires exhibited higher sensitivity to Cl2 gas than ZnO and WO3 nanowires. The response (RCl2/Rair) of the SnO2 nanowire sensor to 50 ppb Cl2 at 50 °C was about 57. Hence, SnO2 nanowires can be an excellent sensing material for detecting Cl2 gas at the ppb level under low temperatures. Abnormal sensing characteristics were observed in the WO3 and SnO2 nanowire sensors at certain temperatures; in particular, the response level of these sensors to 5 ppm of Cl2 was lower than that to 2.5 ppm of Cl2. The sensing mechanism of the SnO2 nanowire sensor was also elucidated by determining Cl2 responses under N2 and dry air as carrier gases. We proved that the Cl2 molecule was first directly adsorbed on the metal oxide surface and was then substituted for pre-adsorbed oxygen, followed by lattice oxygen.

  2. Room-temperature fast construction of outperformed ZnO nanoarchitectures on nanowire-array templates for dye-sensitized solar cells.

    Science.gov (United States)

    Jiang, Wei-Ting; Wu, Chun-Te; Sung, Yu-Hsiang; Wu, Jih-Jen

    2013-02-01

    A ZnO nanoarchitecture composed of nanocactus (NCs) and nanosheets (NSs) is constructed on the ZnO-nanowire (NW)-array template within 4 min by a facile room-temperature (RT) chemical bath deposition (CBD) for use in dye-sensitized solar cells (DSSCs). Compared to the ZnO NW array, the spines and shells of NCs provide larger and more fitting surface for dye adsorption. The NSs developed on the top and side walls of the NWs afford the additional surface for dye adsorption as well as for light scattering. Moreover, the RT-grown ZnO nanostructures possess an upward-shifted conduction band edge and a fast electron transport rate compared to the primary ZnO NW array. With an anode thickness of 9 μm, an efficiency of 5.14% is therefore simply attained in the D149-sensitized ZnO NC-NS DSSC.

  3. Effects of Ce Ion-Modification on an Open Circuit Photovoltage Properties of ZnO Nanowires-Based Dye-Sensitized Solar Cell.

    Science.gov (United States)

    Choi, Seok Cheol; Sohn, Sang Ho

    2015-02-01

    We investigated the photoelectrochemical effects on Ce ion-modified ZnO nanowires for dye-sensitized solar cells (DSSCs), preparing four kinds of samples grown in solutions with 0, 1, 2, and 3 atomic percent (at%) of Ce precursors. It was found that Ce ion modifications lead to an increase in the lattice constant of ZnO nanowires, resulting in widening of their PL visible band and UV blueshift. I-V results tell that the photoelectrochemical properties increase in the order of 1, 2, 0, and 3 at% Ce ion-modified ZnO nanowire-based DSSCs. To further analyze and explain the experimental results, we measured absorbance, incident to photon-to-current efficiency (IPCE), and concluded that the DSSCs fabricated by using 3 at% Ce ion-modified ZnO nanowires exhibit the best device performances due to large VOC enhancements, suggesting that Ce ion modification leads to the VOC, changes of DSSCs, which can be explained by Burstein-Moss effect.

  4. Fabrication of nanowires of Al-doped ZnO using nanoparticle assisted pulsed laser deposition (NAPLD) for device applications

    Energy Technology Data Exchange (ETDEWEB)

    Thanka Rajan, S. [ECMS Division, CSIR – Central Electrochemical Research Institute, Karaikudi 630 006 (India); Subramanian, B., E-mail: subramanianb3@gmail.com [ECMS Division, CSIR – Central Electrochemical Research Institute, Karaikudi 630 006 (India); Nanda Kumar, A.K.; Jayachandran, M. [ECMS Division, CSIR – Central Electrochemical Research Institute, Karaikudi 630 006 (India); Ramachandra Rao, M.S. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India)

    2014-01-25

    Graphical abstract: -- Highlights: • Novel technique of NP assisted PLD was employed to obtain Al doped ZnO. • AZO nano wires with aspect ratios exceeding 20 were obtained at 500 sccm Ar gas pressure. • AZO films belong to the most stable wurtzite type. • Films show near band edge emission and defect related emission. -- Abstract: Aluminium doped zinc oxide (AZO) nanostructures have been successfully synthesized on sapphire substrates by using nanoparticle assisted pulsed laser deposition (NAPLD) in Ar atmosphere without using any catalyst. The growth of the AZO nanowires has been investigated by varying the argon flow rates. The coatings have been characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM), Diffuse Reflectance Spectroscopy (DRS), Laser Raman spectroscopy and Photoluminescence spectroscopy. The results of XRD indicate that the deposited films are crystalline ZnO with hexagonal wurtzite structure with (0 0 2) preferred orientation. FESEM images also clearly reveal the hexagonal structure and the formation of nanowires with aspect ratios between 15 and 20. The surface roughness value of 9.19 nm was observed from AFM analysis. The optical properties of the sample showed that under excitation with λ = 325 nm, an emission band was observed in UV and visible region. The characteristic Raman peaks were detected at 328, 380, 420, 430 cm{sup −1}.

  5. Optimization of the design of extremely thin absorber solar cells based on electrodeposited ZnO nanowires.

    Science.gov (United States)

    Lévy-Clément, Claude; Elias, Jamil

    2013-07-22

    The properties of the components of ZnO/CdSe/CuSCN extremely thin absorber (ETA) solar cells based on electrodeposited ZnO nanowires (NWs) were investigated. The goal was to study the influence of their morphology on the characteristics of the solar cells. To increase the energy conversion efficiency of the solar cell, it was generally proposed to increase the roughness factor of the ZnO NW arrays (i.e. to increase the NW length) with the purpose of decreasing the absorber thickness, improving the light scattering, and consequently the light absorption in the ZnO/CdSe NW arrays. However, this strategy increased the recombination centers, which affected the efficiency of the solar cell. We developed another strategy that acts on the optical configuration of the solar cells by increasing the diameter of the ZnO NW (from 100 to 330 nm) while maintaining a low roughness factor. We observed that the scattering of the ZnO NW arrays occurred over a large wavelength range and extended closer to the CdSe absorber bandgap, and this led to an enhancement in the effective absorption of the ZnO/CdSe NW arrays and an increase in the solar cell characteristics. We found that the thicknesses of CuSCN above the ZnO/CdSe NW tips and the CdSe coating layer were optimized at 1.5 μm and 30 nm, respectively. Optimized ZnO/CdSe/CuSCN solar cells exhibiting 3.2% solar energy conversion efficiency were obtained by using 230 nm diameter ZnO NWs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Hierarchical growth of TiO2 nanosheets on anodic ZnO nanowires for high efficiency dye-sensitized solar cells

    Science.gov (United States)

    Miles, David O.; Lee, Chang Soo; Cameron, Petra J.; Mattia, Davide; Kim, Jong Hak

    2016-09-01

    We present a novel route to hierarchical core-shell structures consisting of an anodic ZnO nanowire core surrounded by a shell of TiO2 nanosheets (ZNW@TNS). This material combines the beneficial properties of enhanced electron transport, provided by the nanowire core, with the high surface area and chemical stability of the TiO2 shell. Quasi-solid-state dye-sensitized solar cells (qssDSSCs) are prepared using different quantities of either the bare ZnO nanowires or the hierarchical nanowire structures and the effect on cell performance is examined. It is found that whilst the addition of the bare ZnO nanowires results in a decrease in cell performance, significant improvements can be achieved with the addition of small quantities of the hierarchical structures. Power conversion efficiencies of up to 7.5% are achieved under 1 Sun, AM 1.5 simulated sunlight, with a ∼30% increase compared to non-hierarchical mesoporous TiO2 films. A solid-state DSSC (ssDSSC) with a single component solid polymer also exhibits excellent efficiency of 7.2%. The improvement in cell performance is related to the improved light scattering, surface area and electron transport properties via the use of reflectance spectroscopy, BET surface area measurements and electrochemical impedance spectroscopy.

  7. Thermo-enhanced field emission from ZnO nanowires: Role of defects and application in a diode flat panel X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhipeng; Chen, Daokun; Chen, Wenqing; Chen, Yicong; Song, Xiaomeng; Zhan, Runze; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun, E-mail: stscjun@mail.sysu.edu.cn

    2017-03-31

    Highlights: • A thermo-enhanced field emission phenomenon was observed from dendritic ZnO nanowires under the temperature of 323–723 K. • Defect-assisted field emission mechanism was proposed and quantitative calculation fits well with the experiment results. • The mechanism was verified by the field emission from ZnO nanowires with different defect concentrations. • A diode X-ray source making use of thermo-enhanced field emission phenomenon was proposed for separate tuning of dose and energy. - Abstract: A thermo-enhanced field emission phenomenon was observed from ZnO nanowires. The field emission current increased by almost two orders of magnitude under a constant applied electric field, and the turn-on field decreased from 6.04 MV/m to 5.0 MV/m when the temperature increased from 323 to 723 K. The Poole–Frenkel electron excitation from the defect-induced trapping centers to the conduction band under high electric fields is believed to be the primary cause of the observed phenomenon. The experimental results fit well with the proposed physical model. The field emission from ZnO nanowires with different defect concentrations further confirmed the role of defects. Using the thermo-enhanced field emission phenomenon, a diode flat panel X-ray source was demonstrated, for which the energy and dose can be separately tuned. The thermo-enhanced field emission phenomenon observed from ZnO nanowires could be an effective way to realize a large area flat panel multi-energy X-ray source.

  8. Parameters Influencing the Growth of ZnO Nanowires as Efficient Low Temperature Flexible Perovskite-Based Solar Cells

    Directory of Open Access Journals (Sweden)

    Alex Dymshits

    2016-01-01

    Full Text Available Hybrid organic-inorganic perovskite has proved to be a superior material for photovoltaic solar cells. In this work we investigate the parameters influencing the growth of ZnO nanowires (NWs for use as an efficient low temperature photoanode in perovskite-based solar cells. The structure of the solar cell is FTO (SnO2:F-glass (or PET-ITO (In2O3·(SnO2 (ITO on, polyethylene terephthalate (PET/ZnAc seed layer/ZnO NWs/CH3NH3PbI3/Spiro-OMeTAD/Au. The influence of the growth rate and the diameter of the ZnO NWs on the photovoltaic performance were carefully studied. The ZnO NWs perovskite-based solar cell demonstrates impressive power conversion efficiency of 9.06% on a rigid substrate with current density over 21 mA/cm2. In addition, we successfully fabricated flexible perovskite solar cells while maintaining all fabrication processes at low temperature, achieving power conversion efficiency of 6.4% with excellent stability for over 75 bending cycles.

  9. Parameters Influencing the Growth of ZnO Nanowires as Efficient Low Temperature Flexible Perovskite-Based Solar Cells.

    Science.gov (United States)

    Dymshits, Alex; Iagher, Lior; Etgar, Lioz

    2016-01-19

    Hybrid organic-inorganic perovskite has proved to be a superior material for photovoltaic solar cells. In this work we investigate the parameters influencing the growth of ZnO nanowires (NWs) for use as an efficient low temperature photoanode in perovskite-based solar cells. The structure of the solar cell is FTO (SnO₂:F)-glass (or PET-ITO (In₂O₃·(SnO₂) (ITO)) on, polyethylene terephthalate (PET)/ZnAc seed layer/ZnO NWs/CH₃NH₃PbI₃/Spiro-OMeTAD/Au. The influence of the growth rate and the diameter of the ZnO NWs on the photovoltaic performance were carefully studied. The ZnO NWs perovskite-based solar cell demonstrates impressive power conversion efficiency of 9.06% on a rigid substrate with current density over 21 mA/cm². In addition, we successfully fabricated flexible perovskite solar cells while maintaining all fabrication processes at low temperature, achieving power conversion efficiency of 6.4% with excellent stability for over 75 bending cycles.

  10. High-performance flexible ZnO nanorod UV photodetectors with a network-structured Cu nanowire electrode.

    Science.gov (United States)

    Kwon, Do-Kyun; Lee, Su Jeong; Myoung, Jae-Min

    2016-09-22

    In this work, vertically aligned zinc oxide (ZnO) nanorod (NR)-based flexible ultraviolet (UV) photodetectors were successfully fabricated on a polyimide (PI) substrate with a copper (Cu) nanowire (NW) electrode. To enhance the flexibility and sensing properties, the entangled networks of Cu NWs were applied to UV photodetectors as a flexible electrode. Here, Cu NWs have a high conductivity with a low cost compared to other metals to achieve a Schottky contact with ZnO NRs. Moreover, because of forming a network structure, the surface of the sensing material has a large contact area with oxygen molecules, resulting in a faster response time. The Cu NW electrode exhibited a high optical transmittance of 90%, a considerable sheet resistance of 50 Ω sq(-1), and a work function of 5.12 eV. Consequentially, the fabricated UV photodetector with Cu NW electrodes showed excellent UV sensing properties with a very fast rising time of 0.7 s and a decay time of 1.9 s in the dark and under UV illumination (365 nm, 0.40 mW cm(-2)) at a reverse bias of -2.0 V. Furthermore, during the bending test at a radius of curvature of 5 mm, the flexible ZnO NR UV photodetectors with Cu NW electrodes exhibited almost unchanged UV sensing properties even after 5000 cycles.

  11. {sup 119}Sn CEMS study of Sb doped SnO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, K., E-mail: dqf10204@nifty.com [Tokyo University of Science, PIRC (Japan); Kuzmann, E., E-mail: kuzmann@caesar.elte.hu [Eötvös Loránd University, Pázmány Péter sétány 1/A, Institute of Chemistry (Hungary); Garg, V. K.; Oliveira, A. C. de [University of Brasília, Institute of Physics (Brazil); Stichleutner, S.; Homonnay, Z. [Eötvös Loránd University, Pázmány Péter sétány 1/A, Institute of Chemistry (Hungary)

    2016-12-15

    Sb doped SnO{sub 2} films prepared by DC sputtering and heating were characterized by {sup 119}Sn conversion electron Mössbauer spectrometry (CEMS). An asymmetric doublet was observed in the Mössbauer spectra of 1 %, 3 %, and 10 % Sb doped SnO{sub 2} films. The peak ratios of doublets are considered to be due to the columnar crystal growth on the substrate. With the doping level of Sb, both the isomer shift (δ) and the quadrupole splitting (Δ) increased. After annealing, δ increased and Δ decreased for each sample. These results suggest the followings. The electron doping of the SnO{sub 2} lattice by pentavalent Sb induces the increase of the electron density at the Sn{sup IV} nucleus. The annealing process leads to more complete accommodation of the Sb dopant that results in more effective electron doping and therefore increasing isomer shift for tin. Simultaneously, the distortion of the lattice caused by Sb is relaxed and the quadrupole splitting decreases.

  12. Construction of 1D SnO2-coated ZnO nanowire heterojunction for their improved n-butylamine sensing performances

    Science.gov (United States)

    Wang, Liwei; Li, Jintao; Wang, Yinghui; Yu, Kefu; Tang, Xingying; Zhang, Yuanyuan; Wang, Shaopeng; Wei, Chaoshuai

    2016-10-01

    One-dimensional (1D) SnO2-coated ZnO nanowire (SnO2/ZnO NW) N-N heterojunctions were successfully constructed by an effective solvothermal treatment followed with calcination at 400 °C. The obtained samples were characterized by means of XRD, SEM, TEM, Scanning TEM coupled with EDS and XPS analysis, which confirmed that the outer layers of N-type SnO2 nanoparticles (avg. 4 nm) were uniformly distributed onto our pre-synthesized n-type ZnO nanowire supports (diameter 80~100 nm, length 12~16 μm). Comparisons of the gas sensing performances among pure SnO2, pure ZnO NW and the as-fabricated SnO2/ZnO NW heterojunctions revealed that after modification, SnO2/ZnO NW based sensor exhibited remarkably improved response, fast response and recovery speeds, good selectivity and excellent reproducibility to n-butylamine gas, indicating it can be used as promising candidates for high-performance organic amine sensors. The enhanced gas-sensing behavior should be attributed to the unique 1D wire-like morphology of ZnO support, the small size effect of SnO2 nanoparticles, and the semiconductor depletion layer model induced by the strong interfacial interaction between SnO2 and ZnO of the heterojunctions. The as-prepared SnO2/ZnO NW heterojunctions may also supply other novel applications in the fields like photocatalysis, lithium-ion batteries, waste water purification, and so on.

  13. Construction of 1D SnO2-coated ZnO nanowire heterojunction for their improved n-butylamine sensing performances.

    Science.gov (United States)

    Wang, Liwei; Li, Jintao; Wang, Yinghui; Yu, Kefu; Tang, Xingying; Zhang, Yuanyuan; Wang, Shaopeng; Wei, Chaoshuai

    2016-10-13

    One-dimensional (1D) SnO2-coated ZnO nanowire (SnO2/ZnO NW) N-N heterojunctions were successfully constructed by an effective solvothermal treatment followed with calcination at 400 °C. The obtained samples were characterized by means of XRD, SEM, TEM, Scanning TEM coupled with EDS and XPS analysis, which confirmed that the outer layers of N-type SnO2 nanoparticles (avg. 4 nm) were uniformly distributed onto our pre-synthesized n-type ZnO nanowire supports (diameter 80~100 nm, length 12~16 μm). Comparisons of the gas sensing performances among pure SnO2, pure ZnO NW and the as-fabricated SnO2/ZnO NW heterojunctions revealed that after modification, SnO2/ZnO NW based sensor exhibited remarkably improved response, fast response and recovery speeds, good selectivity and excellent reproducibility to n-butylamine gas, indicating it can be used as promising candidates for high-performance organic amine sensors. The enhanced gas-sensing behavior should be attributed to the unique 1D wire-like morphology of ZnO support, the small size effect of SnO2 nanoparticles, and the semiconductor depletion layer model induced by the strong interfacial interaction between SnO2 and ZnO of the heterojunctions. The as-prepared SnO2/ZnO NW heterojunctions may also supply other novel applications in the fields like photocatalysis, lithium-ion batteries, waste water purification, and so on.

  14. Charge-Separation Kinetics of Photoexcited Oxygen Vacancies in ZnO Nanowire Field-Effect Transistors

    Science.gov (United States)

    Lu, Ming-Pei; Chen, Chieh-Wei; Lu, Ming-Yen

    2016-11-01

    Photoinduced atomic structural transitions of negative-U defects: neutral oxygen vacancies (VO 0 ), accompanied by lattice relaxation, can form ionized 1 + and 2 + vacancy defects in ZnO materials, giving rise to an optoelectronic phenomenon named "persistent photoconductivity," thereby limiting the applications of ZnO materials in optoelectronic fields. Nevertheless, very little is known about the kinetics of the separation-recombination interactions between an electron and an ionized oxygen vacancy, constituting a photoexcited charge pair, in nanoscale ZnO material systems, especially when considering the effect of electric fields. In this report, we describe the charge-separation kinetics of photoexcited VO 0 defects in ZnO nanowire (NW) field-effect transistor (FET) systems, examined through modulation of the surface electric field of the ZnO NW. We apply oxygen plasma treatment to tailor the doping concentration within the ZnO NWs with the goal of modulating the electric field within their surface space-charge layers. X-ray photoelectron spectroscopy and low-frequency current-noise spectroscopy are applied to identify the change in the density of oxygen-vacancy defects near the NW surface after oxygen plasma treatment. A model describing the initial stage of the photoconductance responses associated with the formation of the photoinduced ionized 1 + state of the oxygen-vacancy defects (VO + ) in the fully depleted ZnO NW FETs in the low-photoconductance regime upon UV excitation is proposed to extract the charge-separation probabilities of the photoexcited electron/VO + pair. Accordingly, the charge-separation probability increases from approximately 0.0012 to 0.042 upon increasing the electric field at the NW surface from approximately 7.5 ×106 to 5.0 ×107 V m-1 . Moreover, we employ modified Braun empirical theory to model the effect of the electric field on the charge-separation behavior of photoexcited electron/VO + pairs in ZnO NWs, obtaining a

  15. Effect of Mn-doping on the growth mechanism and electromagnetic properties of chrysanthemum-like ZnO nanowire clusters

    Science.gov (United States)

    Yan, Jun-Feng; You, Tian-Gui; Zhang, Zhi-Yong; Tian, Jiang-Xiao; Yun, Jiang-Ni; Zhao, Wu

    2011-04-01

    Chrysanthemum-like ZnO nanowire clusters with different Mn-doping concentrations are prepared by a hydrothermal process. The microstructure, morphology and electromagnetic properties are characterized by x-ray diffractometer high-resolution transmission electron microscopy (HRTEM), a field emission environment scanning electron microscope (FEESEM) and a microwave vector network analyser respectively. The experimental results indicate that the as-prepared products are Mn-doped ZnO single crystalline with a hexagonal wurtzite structure, that the growth habit changes due to Mn-doping and that a good magnetic loss property is found in the Mn-doped ZnO products, and the average magnetic loss tangent tanδm is up to 0.170099 for 3% Mn-doping, while the dielectric loss tangent tanδe is weakened, owing to the fact that ions Mn2+ enter the crystal lattice of ZnO.

  16. Structural, elastic and magnetic properties of Mn and Sb doped chromium nitride – An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Ikram Un Nabi Lone; Sheik Sirajuddeen M Mohamed, E-mail: msheiksiraj@bsauniv.ac.in; Shameem Banu, I.B.; Sathik Basha, S.

    2017-05-01

    Structural, magnetic and elastic properties of Mn and Sb doped CrN were investigated by the electronic band structure calculations using Full Potential Linear Augmented Plane Wave (FP-LAPW) method. The host compound CrN was doped with Mn and Sb separately, in the doping concentration of 12.5% to replace Cr atoms. The introduction of Mn and Sb atoms replacing the Cr atoms does not change the structural stability of the compound. The changes in magnetic and elastic properties were investigated and compared in GGA and GGA+U methods. The doped CrN undergoes a relative increase in the magnetic order with the substitution of Mn and Sb atoms. In GGA method, the magnetic moments are found to be greater in Mn doped CrN than that found in Sb doped Cr{sub 0.875}NSb{sub 0.125}. When doped with Sb, the elastic moduli such as Young’s modulus, bulk modulus and rigidity modulus show a relative increase in comparison with that in Mn doped CrN. Using Hubbard model in GGA+U method, both the magnetic and elastic properties increase in Mn and Sb doped compounds. - Highlights: • Mn and Sb doped Chromium Nitride. • Structural properties. • Magnetic properties. • Elastic properties.

  17. Fabrication of one-dimensional ZnO nanotube and nanowire arrays with an anodic alumina oxide template via electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yen-Hsing; Shen, Yu-Min [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Wang, Sheng-Chang, E-mail: scwang@mail.stust.edu.tw [Department of Mechanical Engineering, Southern Taiwan University, Tainan 710, Taiwan (China); Huang, Jow-Lay, E-mail: jlh888@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2014-11-03

    In this work, two kinds of one-dimensional ZnO nanowires (NWs) and nanotubes (NTs) were synthesized by using electrochemical deposition with the aid of a high aspect ratio anodic alumina oxide (AAO) template. ZnO NWs and NTs were characterized by using X-ray diffraction, field emission scanning microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. An AAO template was fabricated by two-step anodization in 0.3 M oxalic acid with a voltage of 80 V. The thickness and channel diameter of the AAO template were about 150 μm and 120–150 nm, respectively. The morphologies of the ZnO nanostructures synthesized under 20 vol.% H{sub 2}O{sub 2} with various electrolyte concentrations of 0.1 M and 0.5 M ZnSO{sub 4}, were NTs and NWs, respectively. Both NTs and NWs were uniform in size, which corresponded to the sizes of AAO pores. The thickness of the NTs walls can be controlled based on the deposition time and current density. The crystallinity of the ZnO NTs and NWs annealing in the air were restricted by AAO pore. The growth of the ZnO NTs and NWs was caused by heterogeneous nucleation, and different growth rates through the wall of the AAO will result in different nanostructures, with the growth of the NTs being slower than that of the NWs. - Highlights: • Templated electrodeposition of ZnO nanotubes (NTs) and nanowires (NWs) • ZnO NTs and NWs fabricated using anodic alumina oxide templates • The growth mechanism of ZnO NTs and NWs is modeled.

  18. Size-controlled growth of ZnO nanowires by catalyst-free high-pressure pulsed laser deposition and their optical properties

    Directory of Open Access Journals (Sweden)

    W. Z. Liu

    2011-06-01

    Full Text Available Single crystalline ZnO nanowires were fabricated on Si (100 substrates by catalyst-free high-pressure pulsed laser deposition. It is found that the nanowires start to form when the substrate temperature and growth pressure exceed the critical values of 700 oC and 700 Pa, and their size strongly depends on these growth conditions. That is, the aspect ratio of the nanowires decreases with increasing temperature or decreasing pressure. Such a size dependence on growth conditions was discussed in terms of surface migration and scattering of ablated atoms. Room-temperature photoluminescence spectrum of ZnO nanowires shows a dominant near-band-edge emission peak at 3.28 eV and a visible emission band centered at 2.39 eV. Temperature-dependent photoluminescence studies reveal that the former consists of the acceptor-bound exciton and free exciton emissions; while the latter varies in intensity with the aspect ratio of the nanowires and is attributed to the surface-mediated deep level emission.

  19. Growth of ZnO nanowires on fibers for one-dimensional flexible quantum dot-sensitized solar cells.

    Science.gov (United States)

    Chen, Haining; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2012-02-24

    One-dimensional flexible solar cells were fabricated through vertical growth of ZnO nanowires on freestanding carbon fibers and subsequent deposition of CdS quantum dots (QDs). Under light illumination, excitons were generated in the CdS QDs and dissociated in the ZnO/CdS interface. Photoelectrochemical characterization indicates that fiber quantum dot-sensitized solar cells (QDSCs) could effectively absorb visible light and convert it to electric energy. The photoelectrochemical performance was enhanced after the deposition of a ZnS passivating layer on the CF/ZnO/CdS surface. The highest conversion efficiency of about 0.006% was achieved by the fiber QDSCs. A higher conversion efficiency was expected to be achieved after some important parameters and cell structure were optimized and improved.

  20. UV Sensing Properties of ZnO Nanowires Grown on Glass by Rapid Thermal Oxidation of Zinc Films

    Science.gov (United States)

    Mihailova, I.; Gerbreders, V.; Sļedevskis, Ē.; Bulanovs, A.; Paškevičs, V.

    2014-08-01

    The nanostructured ZnO thin films were successfully synthesized by rapid thermal oxidation of metallic zinc films without catalysts or additives. On the surface of thin films the formation of ZnO nanowires was observed. In the work, the optical and electrical parameters and photoresponses of the obtained ZnO thin films were investigated. Nanostructured thin films of the type have a promising potential for the use in optoelectronics, sensor technique and biomedical sciences Šī darba galvenais mērķis bija izpētīt UV fotodetektora izgatavošanas iespējamību uz nanostrukturētu ZnO plāno kārtiņu bāzes, kas sintezētas termiski oksidējot Zn plānās kārtiņas. Termiskās oksidēšanas rezultātā tika novērota adatveidīgu ZnO nanostruktūru formēšanās uz kārtiņu virsmas. Izpētītas iegūto paraugu optiskās un elektriskās īpašības, kā arī fotoreakcija. Tika konstatēts, ka iegūto nanostrukturēto ZnO kārtiņu elektriskā vadītspēja ir ārkārtīgi jutīga pret UV starojumu, taču, apstarojot ar redzamo gaismu, strāva paliek gandrīz nemainīga. Kārtiņu elektriskās vadītspējas fotoreakcija ir atkarīga arī no nanostruktūru daudzuma uz virsmas. Visaugstākā UV fotovadītspēja tika novērota paraugam ar vislielāko ZnO nanoadatu koncentrāciju. UV gaismas inducētais vadītspējas pieaugums ļauj ZnO nanoadatas reversīvi pārslēgt starp stāvokļiem "ieslēgts" un "izslēgts". Līdz ar to, šīs fotojutīgās nanoadatas var tikt izmantotas UV gaismas detektoros un optiskajos slēdžos. Šādas nanostrukturētas plānās kārtiņas var tikt pielietotas arī ķīmiskajos un bioloģiskajos sensoros, pjezoelektriskajās ierīcēs, saules elementos utt. Turklāt, šādu nanostrukturēto ZnO plāno kārtiņu sintēzes process ir salīdzinoši lēts un vienkāršs, dodot iespēju liela mēroga produkcijas ražošanai

  1. Electronic and magnetic properties of Ga, Ge, P and Sb doped monolayer arsenene

    Science.gov (United States)

    Bai, M.; Zhang, W. X.; He, C.

    2017-07-01

    In this paper, the structural, electronic, and magnetic properties of Ga, Ge, P and Sb doped monolayer arsenene have been systematically investigated by first-principles calculations based on density functional theory. The properties of monolayer arsenene can be effectively tuned by substitutional doping. Especially, the dopant Ga could lead to an indirect-to-direct bandgap transition and doping a Ge atom could exhibit dilute magnetic semiconductor property. In addition, the second Ge atom slightly prefers to occupy the next nearest-neighbor site of As atom to form the complex substituted defect (GeAs - As - GeAs) in As30Ge2 system and is found to be anti-ferromagnetic coupling. The diverse electronic and magnetic properties highlight the potential applications of monolayer arsenene in electronics, optoelectronics and spintronics.

  2. Facile aqueous growth of 150 nm ZnO nanowires for energy harvester: Enhanced output voltage using Pt sputtered electrode

    Directory of Open Access Journals (Sweden)

    Mansoor Ahmad

    2016-03-01

    Full Text Available Facile aqueous growth technique was adopted to grow diameter controlled 150 nm ZnO nanowires on an ITO (indium tin oxide coated PET (poly ethylene terephthalate substrate. Prior to nanowire growth, a pure wurtazite structured ZnO seed layer was grown on PET substrates. Surface morphology and elemental composition were investigated by SEM (scanning electron microscopy and EDS (energy dispersive spectroscopy respectively. An enhanced output piezoelectric potential of 1.858 with an output power density 215.4 mW/cm2 was achieved using a Pt sputtered electrode. We have obtained enhanced values of output voltage compared to our previously reported voltage values of 1.34 V (Ahmad et al. 2014.

  3. Enhancement in red emission at room temperature from europium doped ZnO nanowires by 1,10 phenanthroline-europium interface induced resonant excitations

    Directory of Open Access Journals (Sweden)

    Soumen Dhara

    2017-02-01

    Full Text Available We show that europium doped ZnO nanowires after surface modification with organic ligand, 1,10 phenanthroline (phen leads to strong red emission at 613 nm which is a characteristic emission from the atomic levels of Eu3+. Surface modification with phen leads to formation of phenanthroline-europium interface on the surface of the nanowires due to attachment of Eu3+ ions. After an optimized surface modification with phen, intensity of both the UV emission (band edge and red emission improved by two orders of magnitude at room temperature. We observed multiple energy transfer pathways to the energy levels of Eu3+ ions through the phenanthroline-europium interface, which found to be very effective to the significant enhancement of emission from the dopant Eu3+. This study shows a new insight in to the energy transfer process from phen to the europium doped ZnO system.

  4. ZnO nanowires for the modification of evanescence-field sensors and the development of novel solar cells; ZnO-Nanodraehte zur Modifizierung von Evaneszenzfeldsensoren und der Entwicklung neuartiger Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Boerner, Susanne

    2008-10-02

    The photoluminescence of single structures and the nanowire ensemble were analyzed and compared. This pursued in dependence on the excitation density and the sample temperature. The excitonic emission contributes essentially to the near-band-edge photoluminescence. The ZnO nanowire ensemble exhibits a laser threshold of 500 kW/cm{sup 2} at room temperature. To the photoluminescence spectra the single exciton processes were assigned. The wave-guiding properties were practically detected by means of optical microscopy and micromanipulation. While the main topic of this thesis lied in the analysis of the optical properties of the ZnO nanowires in the last part the implementation of nanostructures in hybrid solar cells was discussed and first results of the characterization of the material complex of p-conducting polymer (Clevios P) and ZnO nanowires presented.

  5. Single ZnO nanowire/p-type GaN heterojunctions for photovoltaic devices and UV light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Bie, Ya-Qing; Liao, Zhi-Min; Wang, Peng-Wei; Zhou, Yang-Bo; Han, Xiao-Bing; Ye, Yu; Zhao, Qing; Wu, Xiao-Song; Dai, Lun; Xu, Jun; Sang, Li-Wen; Deng, Jun-Jing; Laurent, K.; Yu, Da-Peng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Leprince-Wang, Y. [Laboratoire de Physique des Materiaux Divises et Interfaces (LPMDI), CNRS-UMR 8108, Universite Paris-Est., Marne la Vallee Cedex 2, 77454, (France)

    2010-10-08

    We fabricate heterojunctions consisting of a single n-type ZnO nanowire and a p-type GaN film. The photovoltaic effect of heterojunctions exhibits open-circuit voltages ranging from 2 to 2.7 V, and a maximum output power reaching 80 nW. Light-emitting diodes with UV electroluminescence based on the heterojunctions are demonstrated. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  6. Low-Cost and High-Productivity Three-Dimensional Nanocapacitors Based on Stand-Up ZnO Nanowires for Energy Storage.

    Science.gov (United States)

    Wei, Lei; Liu, Qi-Xuan; Zhu, Bao; Liu, Wen-Jun; Ding, Shi-Jin; Lu, Hong-Liang; Jiang, Anquan; Zhang, David Wei

    2016-12-01

    Highly powered electrostatic capacitors based on nanostructures with a high aspect ratio are becoming critical for advanced energy storage technology because of their high burst power and energy storage capability. We report the fabrication process and the electrical characteristics of high capacitance density capacitors with three-dimensional solid-state nanocapacitors based on a ZnO nanowire template. Stand-up ZnO nanowires are grown face down on p-type Si substrates coated with a ZnO seed layer using a hydrothermal method. Stacks of AlZnO/Al2O3/AlZnO are then deposited sequentially on the ZnO nanowires using atomic layer deposition. The fabricated capacitor has a high capacitance density up to 92 fF/μm(2) at 1 kHz (around ten times that of the planar capacitor without nanowires) and an extremely low leakage current density of 3.4 × 10(-8) A/cm(2) at 2 V for a 5-nm Al2O3 dielectric. Additionally, the charge-discharge characteristics of the capacitor were investigated, indicating that the resistance-capacitance time constants were 550 ns for both the charging and discharging processes and the time constant was not dependent on the voltage. This reflects good power characteristics of the fabricated capacitors. Therefore, the current work provides an exciting strategy to fabricate low-cost and easily processable, high capacitance density capacitors for energy storage.

  7. Thermo-enhanced field emission from ZnO nanowires: Role of defects and application in a diode flat panel X-ray source

    Science.gov (United States)

    Zhang, Zhipeng; Chen, Daokun; Chen, Wenqing; Chen, Yicong; Song, Xiaomeng; Zhan, Runze; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2017-03-01

    A thermo-enhanced field emission phenomenon was observed from ZnO nanowires. The field emission current increased by almost two orders of magnitude under a constant applied electric field, and the turn-on field decreased from 6.04 MV/m to 5.0 MV/m when the temperature increased from 323 to 723 K. The Poole-Frenkel electron excitation from the defect-induced trapping centers to the conduction band under high electric fields is believed to be the primary cause of the observed phenomenon. The experimental results fit well with the proposed physical model. The field emission from ZnO nanowires with different defect concentrations further confirmed the role of defects. Using the thermo-enhanced field emission phenomenon, a diode flat panel X-ray source was demonstrated, for which the energy and dose can be separately tuned. The thermo-enhanced field emission phenomenon observed from ZnO nanowires could be an effective way to realize a large area flat panel multi-energy X-ray source.

  8. Ligand-free attachment of plasmonic Au nanoparticles on ZnO nanowire to make a high-performance broadband photodetector using a laser-based method

    Science.gov (United States)

    Ram Ghimire, Rishi; Nath, Rajib; Neogy, Rajesh Kr; Raychaudhuri, A. K.

    2017-07-01

    We report a new strategy for ligand-free attachment of plasmonic Au nanoparticles on the surface of a ZnO nanowire to make high-performance broadband photodetectors using a pulsed laser ablation technique in a liquid medium. The photoresponse of the ZnO-based photodetector is enhanced and the photodetection limit is broadened from UV to visible, which can be controlled by varying the concentration of Au nanoparticles attached to the ZnO surface. This Au nanoparticle concentration can be tuned by varying the number of laser pulses used in the ablation process. We found that the responsivity of the detector is 10 mA W-1 for λ ˜ 525 {nm} and increases to as much as 0.4 A W-1 for λ ≤ 400 nm for the maximum Au concentration. The enhanced responsivity was found to be linked to increased absorption over a broad spectral range arising from direct and indirect plasmonic processes due to Au nanoparticle attachment, and the enhanced absorption also leads to a large increment in photocurrent generation. We also found that the attachment of Au nanoparticles makes the relaxation of the photocurrent (persistence) considerably faster in both the UV and visible regions of the spectrum and that the persistence directly depends on the concentration of Au nanoparticles attached to the ZnO nanowire. This single-step pulsed laser ablation-based nanoparticle attachment process can be further used to make other plasmonic nanoparticle-decorated nanowire devices.

  9. Effect of pressure and Al doping on structural and optical properties of ZnO nanowires synthesized by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mohanta, Antaryami [Oak Ridge Institute for Science and Education, Research Participation Program, U.S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC), Redstone Arsenal, AL 35898 (United States); Simmons, Jay G. [Department of Chemistry, Duke University, Durham, NC 27708 (United States); Everitt, Henry O. [U.S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC), Redstone Arsenal, AL 35898 (United States); Shen, Gang; Margaret Kim, Seongsin [Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Kung, Patrick, E-mail: patkung@eng.ua.edu [Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States)

    2014-02-15

    The effect of Al doping concentration and oxygen ambient pressure on the structural and optical properties of chemical vapor deposition-grown, Al-doped ZnO nanowires is studied. As Al doping increases, the strength of the broad visible emission band decreases and the UV emission increases, but the growth rate depends on the oxygen pressure in a complex manner. Together, these behaviors suggest that Al doping is effective in reducing the number of oxygen vacancies responsible for visible emission, especially at low oxygen ambient pressure. The intensities and quantum efficiencies of these emission mechanisms are discussed in terms of the effect growth and doping conditions have on the underlying excitonic decay mechanisms. -- Highlights: • Correlated study of the photoluminescence of undoped and Al-doped ZnO nanowires. • Comparative study of structural and optical properties of ZnO and Al:ZnO nanowires. • Study of excitonic decay relaxation channels as function of pressure and Al doping. • More effective reduction of oxygen vacancies by Al doping at lower pressure.

  10. Three-dimensional mesoscale heterostructures of ZnO nanowire arrays epitaxially grown on CuGaO2 nanoplates as individual diodes.

    Science.gov (United States)

    Forticaux, Audrey; Hacialioglu, Salih; DeGrave, John P; Dziedzic, Rafal; Jin, Song

    2013-09-24

    We report a three-dimensional (3D) mesoscale heterostructure composed of one-dimensional (1D) nanowire (NW) arrays epitaxially grown on two-dimensional (2D) nanoplates. Specifically, three facile syntheses are developed to assemble vertical ZnO NWs on CuGaO2 (CGO) nanoplates in mild aqueous solution conditions. The key to the successful 3D mesoscale integration is the preferential nucleation and heteroepitaxial growth of ZnO NWs on the CGO nanoplates. Using transmission electron microscopy, heteroepitaxy was found between the basal planes of CGO nanoplates and ZnO NWs, which are their respective (001) crystallographic planes, by the observation of a hexagonal Moiré fringes pattern resulting from the slight mismatch between the c planes of ZnO and CGO. Careful analysis shows that this pattern can be described by a hexagonal supercell with a lattice parameter of almost exactly 11 and 12 times the a lattice constants for ZnO and CGO, respectively. The electrical properties of the individual CGO-ZnO mesoscale heterostructures were measured using a current-sensing atomic force microscopy setup to confirm the rectifying p-n diode behavior expected from the band alignment of p-type CGO and n-type ZnO wide band gap semiconductors. These 3D mesoscale heterostructures represent a new motif in nanoassembly for the integration of nanomaterials into functional devices with potential applications in electronics, photonics, and energy.

  11. Near-Field Imaging of Free Carriers in ZnO Nanowires with a Scanning Probe Tip Made of Heavily Doped Germanium

    Science.gov (United States)

    Sakat, Emilie; Giliberti, Valeria; Bollani, Monica; Notargiacomo, Andrea; Pea, Marialilia; Finazzi, Marco; Pellegrini, Giovanni; Hugonin, Jean-Paul; Weber-Bargioni, Alexander; Melli, Mauro; Sassolini, Simone; Cabrini, Stefano; Biagioni, Paolo; Ortolani, Michele; Baldassarre, Leonetta

    2017-11-01

    A novel scanning probe tip made of heavily doped semiconductor is fabricated and used instead of standard gold-coated tips in infrared scattering-type near-field microscopy. Midinfrared near-field microscopy experiments are conducted on ZnO nanowires with a lateral resolution better than 100 nm, using tips made of heavily electron-doped germanium with a plasma frequency in the midinfrared (plasma wavelength of 9.5 μ m ). Nanowires embedded in a dielectric matrix are imaged at two wavelengths, 11.3 and 8.0 μ m , above and below the plasma wavelength of the tips. An opposite sign of the imaging contrasts between the nanowire and the dielectric matrix is observed at the two infrared wavelengths, indicating a clear role of the free-electron plasma in the heavily doped germanium tip in building the imaging contrast. Electromagnetic simulations with a multispherical dipole model accounting for the finite size of the tip are well consistent with the experiments. By comparison of the simulated and measured imaging contrasts, an estimate for the local free-carrier density in the investigated ZnO nanowires in the low 1019 cm-3 range is retrieved. The results are benchmarked against the scattering intensity and phase maps obtained on the same sample with a gold-coated probe tip in pseudoheterodyne detection mode.

  12. Engineering efficient thermoelectrics from large-scale assemblies of doped ZnO nanowires: nanoscale effects and resonant-level scattering.

    Science.gov (United States)

    Brockway, Lance; Vasiraju, Venkata; Sunkara, Mahendra K; Vaddiraju, Sreeram

    2014-09-10

    Recent studies focusing on enhancing the thermoelectric performance of metal oxides were primarily motivated by their low cost, large availability of the component elements in the earth's crust, and their high stability. So far, these studies indicate that n-type materials, such as ZnO, have much lower thermoelectric performance than their p-type counterparts. Overcoming this limitation requires precisely tuning the thermal and electrical transport through n-type metal oxides. One way to accomplish this is through the use of optimally doped bulk assemblies of ZnO nanowires. In this study, the thermoelectric properties of n-type aluminum and gallium dually doped bulk assembles of ZnO nanowires were determined. The results indicated that a high zT of 0.6 at 1000 °C, the highest experimentally observed for any n-type oxide, is possible. The high performance is attributed to the tailoring of the ZnO phase composition, nanostructuring of the material, and Zn-III band hybridization-based resonant scattering.

  13. In situ ZnO nanowire growth to promote the PVDF piezo phase and the ZnO-PVDF hybrid self-rectified nanogenerator as a touch sensor.

    Science.gov (United States)

    Li, Zetang; Zhang, Xu; Li, Guanghe

    2014-03-28

    A PVDF-ZnO nanowires (NWs) hybrid generator (PZHG) was designed. A simple, cost effective method to produce the PVDF β phase by nano force is introduced. With the ZnO NWs growing, the in situ nano extension force promotes the phase change. A theoretical analysis of the ZnO NWs acting as a self-rectifier of the nano generator is established. The ZnO NWs acted as a self-adjustment diode to control the current output of the PZHG by piezo-electric and semi-conductive effects. Based on the self-controllability of the piezoelectric output, three kinds of finger touching are distinguished by the output performances of the PZHG, which is applicable to an LCD touch pad.

  14. Low-Temperature Preparation of Ag-Doped ZnO Nanowire Arrays, DFT Study, and Application to Light-Emitting Diode.

    Science.gov (United States)

    Pauporté, Thierry; Lupan, Oleg; Zhang, Jie; Tugsuz, Tugba; Ciofini, Ilaria; Labat, Frédéric; Viana, Bruno

    2015-06-10

    Doping ZnO nanowires (NWs) by group IB elements is an important challenge for integrating nanostructures into functional devices with better and tuned performances. The growth of Ag-doped ZnO NWs by electrodeposition at 90 °C using a chloride bath and molecular oxygen precursor is reported. Ag acts as an electrocatalyst for the deposition and influences the nucleation and growth of the structures. The silver atomic concentration in the wires is controlled by the additive concentration in the deposition bath and a content up to 3.7 atomic % is reported. XRD analysis shows that the integration of silver enlarges the lattice parameters of ZnO. The optical measurements also show that the direct optical bandgap of ZnO is reduced by silver doping. The bandgap shift and lattice expansion are explained by first principle calculations using the density functional theory (DFT) on the silver impurity integration as an interstitial (Ag(i)) and as a substitute of zinc atom (Ag(Zn)) in the crystal lattice. They notably indicate that Ag(Zn) doping forms an impurity band because of Ag 4d and O 2p orbital interactions, shifting the Fermi level toward the valence band. At least, Ag-doped ZnO vertically aligned nanowire arrays have been epitaxially grown on GaN(001) substrate. The heterostructure has been inserted in a light emitting device. UV-blue light emission has been achieved with a low emission threshold of 5 V and a tunable red-shifted emission spectrum related to the bandgap reduction induced by silver doping of the ZnO emitter material.

  15. Fabrication and characterization of ZnO nanowires array electrodes with high photocurrent densities: Effects of the seed layer calcination time

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yi-Jing; Liu, Ching-Fang; Hu, Chi-Chang, E-mail: cchu@che.nthu.edu.tw; Kuo, Jen-Hou; Boddula, Rajender

    2017-03-01

    In this work, we demonstrate that vertically grown ZnO nanowire (NW) arrays of the wurzite phase were successfully fabricated on fluorine doped tin oxide (FTO) substrates via a hydrothermal method. The coating of a seed layer onto the FTO substrates was found to favor the growth of a uniform ZnO NWs array which shows saturation in the photocurrent density with a relatively low potential bias. Furthermore, prolonging the calcination time of the seed layer makes the ZnO NWs behave the better charge separation and improve the photo-electrochemical performance. Under the irradiation at a 75 mW cm{sup −2} from a simulated sunlight source, the ZnO NWs array electrode prepared from the seed layer with calcination at 350 °C for 5 h shows a saturated photocurrent density of 514 μA cm{sup −2} and a maximum half-cell solar-to-hydrogen (HC-STH) efficiency of 0.26% was obtained at 0.6 V versus reversible hydrogen electrode (RHE) in neutral electrolyte. - Highlights: • The seed layer annealing time strongly influences the textural and photo-activity of ZnO NWs. • The average diameter and density of ZnO NWs were controlled to 47–70 nm and 46–70 NWs μm{sup −2}, respectively. • ZnO NWs show promising application potential in solar-electrocatalytic water splitting under potential bias. • The ZnO NWs with SL annealing time = 5 h achieve the highest HC-STH efficiency of 0.26% at 0.6 V.

  16. Synthesis of ZnO nanowire arrays on ZnO−TiO{sub 2} mixed oxide seed layer for dye sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Marimuthu, T. [Advanced Materials and Thin Film Physics Lab, Department of Physics, Alagappa University, Karaikudi (India); Anandhan, N., E-mail: anandhan_kn@rediffmail.com [Advanced Materials and Thin Film Physics Lab, Department of Physics, Alagappa University, Karaikudi (India); Thangamuthu, R. [Electrochemical Materials Science Division, CSIR-Central Electrochemical Research Institute, Karaikudi (India); Mummoorthi, M. [Advanced Materials and Thin Film Physics Lab, Department of Physics, Alagappa University, Karaikudi (India); Ravi, G. [Photonic Crystal Lab, Department of Physics, Alagappa University, Karaikudi (India)

    2016-08-25

    ZnO nanowire arrays (NWAs) were synthesized on ZnO−TiO{sub 2} mixed oxide seeded FTO conducting glass plate by two-step sol-gel and hydrothermal method, respectively. X-ray diffraction patterns reveal the presence of mixed and hexagonal phases in seed layer and NWAs, respectively. Scanning electron microscope images showed that the FTO glass plate is uniformly covered with grains and a few nanorods in seed layer and dense NWAs are vertically grown on the seed layer. The hexagonal structure and high crystal quality have been confirmed by micro Raman spectra. Photoluminescence spectra also present that NWAs have high crystal quality and less atomic defects. UV spectra indicate that NWAs are absorbed more dye molecules and it has the band gap equal to bulk material. The efficiency of ZnO−TiO{sub 2} mixed oxide seed layer and ZnO NWAs is found to be 0.56 and 0.84% respectively. Electrochemical impedance spectra reveal that NWAs DSSC has high charge transfer recombination resistance than the seed layer DSSC. - Highlights: • ZnO nanowire arrays were synthesized by two-step sol-gel and hydrothermal method. • The crystal structure and crystalline quality of films are confirmed by Raman spectra. • The emission properties of films are investigated by photoluminescence spectra. • ZnO nanowire arrays (NWAs) have higher charge transfer recombination resistance. • The conversion efficiency of the seed layer and NWAs is to be 0.56 and 0.84%.

  17. Bending-durable colloidal quantum dot solar cell using a ZnO nanowire array as a three-dimensional electron transport layer

    Science.gov (United States)

    Wang, Yinglin; Su, Wei; Zang, Shuaipu; Li, Meiying; Zhang, Xintong; Liu, Yichun

    2017-04-01

    The realization of both high efficiency and strong bending-durability is a critical issue for future applications of colloidal quantum dot solar cells (CQDSCs) in flexible devices. Herein, we fabricated flexible CQDSCs with a three-dimensional electron transport layer (ETL) composed of a ZnO nanowire (NW) array for efficient carrier collection and probed the effect of the NW array on the bendability of flexible cells. The good bendability of cells with ZnO NWs was verified from the consistency of photovoltaic performance during mechanical bending treatment with various bending angles and cycles. The efficient release of stress inside the three-dimensional CQDSCs with the ZnO NW array led to the maintenance of 97% of the initial power conversion efficiency at a bending angle of 160°. In contrast, crack formation on the common planar ETL of CQDSCs formed by ZnO nanoparticles resulted in a degradation of device performance to 77% of the initial one at the same angle. Our research demonstrated that the bending stability of the ZnO NW array may be promising for commercial applications of flexible photovoltaic devices.

  18. Schottky-Gated Probe-Free ZnO Nanowire Biosensor

    KAUST Repository

    Yeh, Ping-Hung

    2009-12-28

    (Figure Presented) A nanowire-based nanosensor for detecting biologically and chemically charged molecules that is probe-free and highly sensitive is demonstrated. The device relies on the nonsymmetrical Schottky contact under reverse bias (see figure) and is much more sensitive than the device based on the symmetric ohmic contact. This approach serves as a guideline for designing more practical chemical and biochemical sensors. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

  19. Studies on Calcium Ion Selectivity of ZnO Nanowire Sensors Using Ionophore Membrane Coatings

    Directory of Open Access Journals (Sweden)

    M. H. Asif

    2008-01-01

    Full Text Available Zinc oxide nanorods with 100 nm diameter and 900 nm length were grown on the surface of a silver wire (0.25 mm in diameter with the aim to produce electrochemical nanosensors. It is shown that the ZnO nanorods exhibit a Ca2+-dependent electrochemical potentiometric behavior in an aqueous solution. The potential difference was found to be linear over a large logarithmic concentration range (1 M to 0.1 M using Ag/AgCl as a reference electrode and the response time was less than one minute. In order to adapt the sensors for calcium ion measurements in biological fluids with sufficient selectivity and stability, plastic membrane coatings containing ionophores were applied. These functionalized ZnO nanorods sensors showed a high sensitivity (26.55 mV/decade and good stability.

  20. Electrodeposited ZnO-nanowire/Cu₂O photovoltaic device with highly resistive ZnO intermediate layer.

    Science.gov (United States)

    Izaki, Masanobu; Ohta, Takayuki; Kondo, Misaki; Takahashi, Toshiaki; Mohamad, Fariza Binti; Zamzuri, Mohd; Sasano, Junji; Shinagawa, Tsutomu; Pauporté, Thierry

    2014-08-27

    Cl-doped ZnO-nanowire (Cl:ZnO-nws)/Cu2O photovoltaic devices were prepared by electrodeposition in aqueous solutions, and the effects of the insertion of the highly resistive ZnO (i-ZnO) layer has been demonstrated by an improvement of the photovoltaic performance. The Cl:ZnO-nws and i-ZnO layer were prepared by electrodeposition in a zinc chloride aqueous solution with saturated molecular oxygen and simple zinc nitrate aqueous solution, respectively. The i-ZnO layer was directly deposited on the Cl:ZnO-nws and suppressed the electrodeposition of the Cu2O layer on the Cl:ZnO-nws. The insertion of the i-ZnO layer between the Cl:ZnO-nws and Cu2O layers induced an improvement in the photovoltaic performance from 0.40 to 1.26% with a 0.35 V open circuit voltage, 7.1 mA·cm(-2) short circuit current density, and 0.52 fill factor due to the reduction of the recombination loss.

  1. Phonon Confinement Induced Non-Concomitant Near-Infrared Emission along a Single ZnO Nanowire: Spatial Evolution Study of Phononic and Photonic Properties

    Directory of Open Access Journals (Sweden)

    Po-Hsun Shih

    2017-10-01

    Full Text Available The impact of mixed defects on ZnO phononic and photonic properties at the nanoscale is only now being investigated. Here we report an effective strategy to study the distribution of defects along the growth direction of a single ZnO nanowire (NW, performed qualitatively as well as quantitatively using energy dispersive spectroscopy (EDS, confocal Raman-, and photoluminescence (PL-mapping technique. A non-concomitant near-infrared (NIR emission of 1.53 ± 0.01 eV was observed near the bottom region of 2.05 ± 0.05 μm along a single ZnO NW and could be successfully explained by the radiative recombination of shallowly trapped electrons V_O^(** with deeply trapped holes at V_Zn^''. A linear chain model modified from a phonon confinement model was used to describe the growth of short-range correlations between the mean distance of defects and its evolution with spatial position along the axial growth direction by fitting the E2H mode. Our results are expected to provide new insights into improving the study of the photonic and photonic properties of a single nanowire.

  2. Phonon Confinement Induced Non-Concomitant Near-Infrared Emission along a Single ZnO Nanowire: Spatial Evolution Study of Phononic and Photonic Properties.

    Science.gov (United States)

    Shih, Po-Hsun; Li, Tai-Yue; Yeh, Yu-Chen; Wu, Sheng Yun

    2017-10-28

    The impact of mixed defects on ZnO phononic and photonic properties at the nanoscale is only now being investigated. Here we report an effective strategy to study the distribution of defects along the growth direction of a single ZnO nanowire (NW), performed qualitatively as well as quantitatively using energy dispersive spectroscopy (EDS), confocal Raman-, and photoluminescence (PL)-mapping technique. A non-concomitant near-infrared (NIR) emission of 1.53 ± 0.01 eV was observed near the bottom region of 2.05 ± 0.05 μm along a single ZnO NW and could be successfully explained by the radiative recombination of shallowly trapped electrons V_O^(**) with deeply trapped holes at V_Zn^''. A linear chain model modified from a phonon confinement model was used to describe the growth of short-range correlations between the mean distance of defects and its evolution with spatial position along the axial growth direction by fitting the E2H mode. Our results are expected to provide new insights into improving the study of the photonic and photonic properties of a single nanowire.

  3. Developing Seedless Growth of ZnO Micro/Nanowire Arrays towards ZnO/FeS2/CuI P-I-N Photodiode Application

    Science.gov (United States)

    Yang, Zhi; Wang, Minqiang; Shukla, Sudhanshu; Zhu, Yue; Deng, Jianping; Ge, Hu; Wang, Xingzhi; Xiong, Qihua

    2015-01-01

    A seedless hydrothermal method is developed to grow high density and vertically aligned ZnO micro/nanowire arrays with low defect density on metal films under the saturated nutrition solution. In particular, the mechanism of seedless method is discussed here. A buffer layer can be confirmed by transmission electron microscopy (TEM), which may release the elastic strain between ZnO and substrate to achieve this highly mismatched heteroepitaxial structures. Based on ZnO micro/nanowire arrays with excellent wettability surface, we prepared ZnO-FeS2-CuI p-i-n photodiode by all-solution processed method with the high rectifying ratio of 197 at ±1 V. Under AM 1.5 condition, the Jsc of 0.5 mA/cm2, on-off current ratio of 371 and fast photoresponse at zero bias voltage were obtained. This good performance comes from excellent collection ability of photogenerated electrons and holes due to the increased depletion layer width for p-i-n structure. Finally, the high responsivity around 900 nm shows the potential as near infrared photodetectors applications. PMID:26077658

  4. Effects of external surface charges on the enhanced piezoelectric potential of ZnO and AlN nanowires and nanotubes

    Directory of Open Access Journals (Sweden)

    Seong Min Kim

    2012-12-01

    Full Text Available We theoretically investigate external surface charge effects on piezoelectric potential of ZnO and AlN nanowires (NWs and nanotubes (NTs under uniform compression. The free carrier depletion caused by negative surface charges via surface functionalization on vertically compressed ZnO and AlN NWs/NTs is simulated using finite element calculation; this indicates the enhancement of piezoelectric potential is due to the free carriers (electrons being fully depleted at the critical surface charge density. Numerical simulations reveal that full coverage of surface charges surrounding the NTs increases the piezoelectric output potential exponentially within a relatively smaller range of charge density compared to the case of NWs for a typical donor concentration (∼1017 cm−3. The model can be used to design functional high-power semiconducting piezoelectric nanogenerators.

  5. Effects of the pH on the Formation and Doping Mechanisms of ZnO Nanowires Using Aluminum Nitrate and Ammonia.

    Science.gov (United States)

    Verrier, Claire; Appert, Estelle; Chaix-Pluchery, Odette; Rapenne, Laetitia; Rafhay, Quentin; Kaminski-Cachopo, Anne; Consonni, Vincent

    2017-10-18

    The elucidation of the fundamental processes in aqueous solution during the chemical bath deposition of ZnO nanowires (NWs) using zinc nitrate and hexamethylenetetramine is of great significance: however, their extrinsic doping by foreign elements for monitoring their optical and electrical properties is still challenging. By combining thermodynamic simulations yielding theoretical solubility plots and speciation diagrams with in situ pH measurements and structural, chemical, and optical analyses, we report an in-depth understanding of the pH effects on the formation and aluminum doping mechanisms of ZnO NWs. By the addition of aluminum nitrate with a given relative concentration for the doping and of ammonia over a broad range of concentrations, the pH is shown to strongly influence the shape, diameter, length, and doping magnitude of ZnO NWs. Tuning the dimensions of ZnO NWs by inhibition of their radial growth only proceeds over a specific pH range, where negatively charged Al(OH)4(-) complexes are predominantly formed and act as capping agents by electrostatically interacting with the positively charged m-plane sidewalls. These complexes further favor the aluminum incorporation and doping of ZnO NWs, which only operate over the same pH range following thermal annealing above 200 °C. These findings reporting a full chemical synthesis diagram reveal the significance of carefully selecting and following the pH to control the morphology of ZnO NWs as well as to achieve their thermally activated extrinsic doping, as required for many nanoscale engineering devices.

  6. A Heterojunction Design of Single Layer Hole Tunneling ZnO Passivation Wrapping around TiO2Nanowires for Superior Photocatalytic Performance

    Science.gov (United States)

    Ghobadi, Amir; Ulusoy, T. Gamze; Garifullin, Ruslan; Guler, Mustafa O.; Okyay, Ali K.

    2016-01-01

    Nanostructured hybrid heterojunctions have been studied widely for photocatalytic applications due to their superior optical and structural properties. In this work, the impact of angstrom thick atomic layer deposited (ALD) ZnO shell layer on photocatalytic activity (PCA) of hydrothermal grown single crystalline TiO2 nanowires (NWs) is systematically explored. We showed that a single cycle of ALD ZnO layer wrapped around TiO2 NWs, considerably boosts the PCA of the heterostructure. Subsequent cycles, however, gradually hinder the photocatalytic activity (PCA) of the TiO2 NWs. Various structural, optical, and transient characterizations are employed to scrutinize this unprecedented change. We show that a single atomic layer of ZnO shell not only increases light harvesting capability of the heterostructure via extension of the absorption toward visible wavelengths, but also mitigates recombination probability of carriers through reduction of surface defects density and introduction of proper charge separation along the core-shell interface. Furthermore, the ultrathin ZnO shell layer allows a strong contribution of the core (TiO2) valence band holes through tunneling across the ultrathin interface. All mechanisms responsible for this enhanced PCA of heterostructure are elucidated and corresponding models are proposed. PMID:27464476

  7. Cl-Doped ZnO Nanowire Arrays on 3D Graphene Foam with Highly Efficient Field Emission and Photocatalytic Properties.

    Science.gov (United States)

    Shao, Dali; Gao, Jian; Xin, Guoqing; Wang, Yiping; Li, Lu; Shi, Jian; Lian, Jie; Koratkar, Nikhil; Sawyer, Shayla

    2015-09-01

    An environmentally friendly, low-cost, and large-scale method is developed for fabrication of Cl-doped ZnO nanowire arrays (NWAs) on 3D graphene foam (Cl-ZnO NWAs/GF), and investigates its applications as a highly efficient field emitter and photocatalyst. The introduction of Cl-dopant in ZnO increases free electrons in the conduction band of ZnO and also leads to the rough surface of ZnO NWAs, which greatly improves the field emission properties of the Cl-ZnO NWAs/GF. The Cl-ZnO NWAs/GF demonstrates a low turn-on field (≈1.6 V μm(-1)), a high field enhancement factor (≈12844), and excellent field emission stability. Also, the Cl-ZnO NWAs/GF shows high photocatalytic efficiency under UV irradiation, enabling photodegradation of organic dyes such as RhB within ≈75 min, with excellent recyclability. The excellent photocatalytic performance of the Cl-ZnO NWAs/GF originates from the highly efficient charge separation efficiency at the heterointerface of Cl-ZnO and GF, as well as improved electron transport efficiency due to the doping of Cl. These results open up new possibilities of using Cl-ZnO and graphene-based hybrid nanostructures for various functional devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Evolution of E-centers during the annealing of Sb-doped Si0.8Ge0.2

    DEFF Research Database (Denmark)

    Kilpeläinen, S.; Tuomisto, F.; Slotte, J.

    2011-01-01

    Evolution of the chemical surroundings of vacancy complexes in Sb-doped ([Sb] = 2 × 1018 and 2 × 1019 cm−3) Si0.8Ge0.2 was studied with positron annihilation spectroscopy in Doppler broadening mode. The study was performed by annealing the samples both isochronally and isothermally. Defect....... The stable state reached after the anneals was found to differ from that measured from an as-grown sample. This difference was deemed to be the result of Ge gathering in small clusters during the annealing thus breaking the initially random Ge distribution....

  9. A case for ZnO nanowire field emitter arrays in advanced x-ray source applications

    Science.gov (United States)

    Robinson, Vance S.; Bergkvist, Magnus; Chen, Daokun; Chen, Jun; Huang, Mengbing

    2016-09-01

    Reviewing current efforts in X-ray source miniaturization reveals a broad spectrum of applications: Portable and/or remote nondestructive evaluation, high throughput protein crystallography, invasive radiotherapy, monitoring fluid flow and particulate generation in situ, and portable radiography devices for battle-front or large scale disaster triage scenarios. For the most part, all of these applications are being addressed with a top-down approach aimed at improving portability, weight and size. That is, the existing system or a critical sub-component is shrunk in some manner in order to miniaturize the overall package. In parallel to top-down x-ray source miniaturization, more recent efforts leverage field emission and semiconductor device fabrication techniques to achieve small scale x-ray sources via a bottom-up approach where phenomena effective at a micro/nanoscale are coordinated for macro-scale effect. The bottom-up approach holds potential to address all the applications previously mentioned but its entitlement extends into new applications with much more ground-breaking potential. One such bottom-up application is the distributed x-ray source platform. In the medical space, using an array of microscale x-ray sources instead of a single source promises significant reductions in patient dose as well as smaller feature detectability and fewer image artifacts. Cold cathode field emitters are ideal for this application because they can be gated electrostatically or via photonic excitation, they do not generate excessive heat like other common electron emitters, they have higher brightness and they are relatively compact. This document describes how ZnO nanowire field emitter arrays are well suited for distributed x-ray source applications because they hold promise in each of the following critical areas: emission stability, simple scalable fabrication, performance, radiation resistance and photonic coupling.

  10. Spatial distribution of neutral oxygen vacancies on ZnO nanowire surfaces: An investigation combining confocal microscopy and first principles calculations

    Science.gov (United States)

    Mun Wong, Kin; Alay-e-Abbas, S. M.; Fang, Yaoguo; Shaukat, A.; Lei, Yong

    2013-07-01

    A qualitative approach using room-temperature confocal microscopy is employed to investigate the spatial distribution of shallow and deep oxygen vacancy (VO) concentrations on the polar (0001) and non-polar (101¯0) surfaces of zinc oxide (ZnO) nanowires (NWs). Using the spectral intensity variation of the confocal photoluminescence of the green emission at different spatial locations on the surface, the VO concentrations of an individual ZnO NW can be obtained. The green emission at different spatial locations on the ZnO NW polar (0001) and non-polar (101¯0) surfaces is found to have maximum intensity near the NW edges, decreasing to a minimum near the NW center. First-principles calculations using simple supercell-slab (SS) models are employed to approximate/model the defects on the ZnO NW (101¯0) and (0001) surfaces. These calculations give increased insight into the physical mechanism behind the green emission spectral intensity and the characteristics of an individual ZnO NW. The highly accurate density functional theory (DFT)-based full-potential linearized augmented plane-wave plus local orbitals (FP-LAPW + lo) method is used to compute the defect formation energy (DFE) of the SSs. Previously, using these SS models, it was demonstrated through the FP-LAPW + lo method that in the presence of oxygen vacancies at the (0001) surface, the phase transformation of the SSs in the graphite-like structure to the wurtzite lattice structure will occur even if the thickness of the graphite-like SSs are equal to or less than 4 atomic graphite-like layers [Wong et al., J. Appl. Phys. 113, 014304 (2013)]. The spatial profile of the neutral VO DFEs from the DFT calculations along the ZnO [0001] and [101¯0] directions is found to reasonably explain the spatial profile of the measured confocal luminescence intensity on these surfaces, leading to the conclusion that the green emission spectra of the NWs likely originate from neutral oxygen vacancies. Another significant

  11. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    Science.gov (United States)

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE.

  12. In-situ growth of ZnO nanowire arrays on the sensing electrode via a facile hydrothermal route for high-performance NO2 sensor

    Science.gov (United States)

    Chen, Xiangxiang; Shen, Yanbai; Zhang, Wei; Zhang, Jin; Wei, Dezhou; Lu, Rui; Zhu, Lijia; Li, Hansen; Shen, Yansong

    2018-03-01

    ZnO nanowire (ZNW) arrays were in-situ grown on the sensing electrode via a facile hydrothermal route for NO2 sensing application. ZNW arrays were prepared by a seed layer deposition on the surface of the sensing electrode using a dipping process in a Zn(CH3COO)2·2H2O ethanol solution followed by a seed growth using a hydrothermal route in the Zn(NO3)2·6H2O-HMTA (C6H12N4) system. The microstructural characterizations of the ZNW arrays by means of XRD, FESEM, TEM, FTIR and XPS showed that ZnO nanowires with the diameters of 80-90 nm and the lengths of 0.6-1 μm had a single crystal hexagonal wurtzite structure. Gas sensing properties demonstrated the response of the sensor based on the ZNW arrays was linearly proportional to the NO2 concentration in the range of 1-30 ppm with good reproducibility and selectivity. The maximum sensor response to NO2 was obtained at an operating temperature of 250 °C. The response and recovery times reduced rapidly with increasing the operating temperature. The growth mechanism and sensing mechanism of the ZNW arrays were discussed in accordance with the deposition of the seed layer and the modulation of the depletion layer, respectively.

  13. Limits of carrier mobility in Sb-doped SnO{sub 2} conducting films deposited by reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bissig, B., E-mail: Benjamin.bissig@empa.ch; Jäger, T.; Tiwari, A. N.; Romanyuk, Y. E. [Laboratory for Thin Films and Photovoltaics, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Ding, L. [Photovoltaics and Thin Film Electronics Laboratory, Ecole Polytechnique Fédérale Lausanne (EPFL), Institute of Microengineering (IMT), Rue de la Maladière 71b, 2002 Neuchâtel (Switzerland)

    2015-06-01

    Electron transport in Sb-doped SnO{sub 2} (ATO) films is studied to unveil the limited carrier mobility observed in sputtered films as compared to other deposition methods. Transparent and conductive ATO layers are deposited from metallic tin targets alloyed with antimony in oxygen atmosphere optimized for reactive sputtering. The carrier mobility decreases from 24 cm{sup 2} V{sup −1} s{sup −1} to 6 cm{sup 2} V{sup −1} s{sup −1} when increasing the doping level from 0 to 7 at. %, and the lowest resistivity of 1.8 × 10{sup −3} Ω cm corresponding to the mobility of 12 cm{sup 2} V{sup −1} s{sup −1} which is obtained for the 3 at. % Sb-doped ATO. Temperature-dependent Hall effect measurements and near-infrared reflectance measurements reveal that the carrier mobility in sputtered ATO is limited by ingrain scattering. In contrast, the mobility of unintentionally doped SnO{sub 2} films is determined mostly by the grain boundary scattering. Both limitations should arise from the sputtering process itself, which suffers from the high-energy-ion bombardment and yields polycrystalline films with small grain size.

  14. Limits of carrier mobility in Sb-doped SnO2 conducting films deposited by reactive sputtering

    Directory of Open Access Journals (Sweden)

    B. Bissig

    2015-06-01

    Full Text Available Electron transport in Sb-doped SnO2 (ATO films is studied to unveil the limited carrier mobility observed in sputtered films as compared to other deposition methods. Transparent and conductive ATO layers are deposited from metallic tin targets alloyed with antimony in oxygen atmosphere optimized for reactive sputtering. The carrier mobility decreases from 24 cm2 V−1 s−1 to 6 cm2 V−1 s−1 when increasing the doping level from 0 to 7 at. %, and the lowest resistivity of 1.8 × 10−3 Ω cm corresponding to the mobility of 12 cm2 V−1 s−1 which is obtained for the 3 at. % Sb-doped ATO. Temperature-dependent Hall effect measurements and near-infrared reflectance measurements reveal that the carrier mobility in sputtered ATO is limited by ingrain scattering. In contrast, the mobility of unintentionally doped SnO2 films is determined mostly by the grain boundary scattering. Both limitations should arise from the sputtering process itself, which suffers from the high-energy-ion bombardment and yields polycrystalline films with small grain size.

  15. Electrical, photoelectrical and morphological properties of ZnO nanofiber networks grown on SiO2 and on Si nanowires

    Directory of Open Access Journals (Sweden)

    Nadia Celeste Vega

    2013-06-01

    Full Text Available ZnO nanofibre networks (NFNs were grown by vapour transport method on Si-based substrates. One type of substrate was SiO2 thermally grown on Si and another consisted of a Si wafer onto which Si nanowires (NWs had been grown having Au nanoparticles catalysts. The ZnO-NFN morphology was observed by scanning electron microscopy on samples grown at 600 °C and 720 °C substrate temperature, while an focused ion beam was used to study the ZnO NFN/Si NWs/Si and ZnO NFN/SiO2 interfaces. Photoluminescence, electrical conductance and photoconductance of ZnO-NFN was studied for the sample grown on SiO2. The photoluminescence spectra show strong peaks due to exciton recombination and lattice defects. The ZnO-NFN presents quasi-persistent photoconductivity effects and ohmic I-V characteristics which become nonlinear and hysteretic as the applied voltage is increased. The electrical conductance as a function of temperature can be described by a modified three dimensional variable hopping model with nanometer-ranged typical hopping distances.

  16. Electrical, photoelectrical and morphological properties of ZnO nanofiber networks grown on SiO{sub 2} and on Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Nadia Celeste; Comedi, David [Universidad Nacional de Tucuman (FACET/UNT), (Argentina). Facultad de Ciencias Exactas y Tecnologia. Dept. de Fisica. Lab. de Fisica del Solido; Audebert, Fernando [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Tirado, Monica, E-mail: mtirado@herrera.unt.edu.ar [Universidad Nacional de Tucuman (FACET/UNT), (Argentina). Facultad de Ciencias Exactas y Tecnologia. Dept. de Fisica. Lab. de Nanomateriales y de Propiedades Dielectricas; Rodriguez, Andres; Rodriguez, Tomas [Universidad Politecnica de Madrid (ETSIT/UPM), Madrid (Spain). Escuela Tecnica Superior de Ingenieros de Telecomucacion. Tecnologia Electronica; Hughes, Gareth M.; Grovenor, Chris R.M. [University of Oxford, Parks Road, OX (United Kingdom). Dept. of Materials

    2013-11-01

    ZnO nanofibre networks (NFNs) were grown by vapour transport method on Si-based substrates. One type of substrate was SiO{sub 2} thermally grown on Si and another consisted of a Si wafer onto which Si nanowires (NWs) had been grown having Au nanoparticles catalysts. The ZnO-NFN morphology was observed by scanning electron microscopy on samples grown at 600 Degree-Sign C and 720 Degree-Sign C substrate temperature, while an focused ion beam was used to study the ZnO NFN/Si NWs/Si and ZnO NFN/SiO{sub 2} interfaces. Photoluminescence, electrical conductance and photo conductance of ZnO-NFN was studied for the sample grown on SiO{sub 2}. The photoluminescence spectra show strong peaks due to exciton recombination and lattice defects. The ZnO-NFN presents quasi-persistent photoconductivity effects and ohmic I-V characteristics which become nonlinear and hysteretic as the applied voltage is increased. The electrical conductance as a function of temperature can be described by a modified three dimensional variable hopping model with nanometer-ranged typical hopping distances. (author)

  17. Simulation of Young’s moduli for hexagonal ZnO [0 0 0 1]-oriented nanowires: first principles and molecular mechanical calculations

    Science.gov (United States)

    Bandura, Andrei V.; Evarestov, Robert A.; Lukyanov, Sergey I.; Piskunov, Sergei; Zhukovskii, Yuri F.

    2017-08-01

    Morphologically reproducible wurtzite-structured zinc oxide nanowires (ZnO NWs) can be synthesized by different methods. Since ZnO NWs have been found to possess piezoelectricity, a comprehensive study of their mechanical properties, e.g. deformations caused by external compression or stretching, is one of the actual tasks of this paper. We have calculated wurtzite-structured [0 0 0 1]-oriented ZnO NWs whose diameters have been varied within 1-5 nm and 1-20 nm ranges when using either ab initio (hybrid DFT-LCAO) or force-field (molecular mechanical) methods, respectively (the minimum diameter d NW of experimentally synthesized NWs has been estimated on average to be ~20 nm). When using both chosen calculation approaches, the values of Young’s moduli determined for the mentioned ranges of NW diameters have been found to be qualitatively compatible (168-169 GPa for 5 nm NW thickness), whereas results of molecular mechanical simulations on Y NW for 20 nm-thick NWs (160-162 GPa) have been qualitatively comparable with those experimentally measured along the [0 0 0 1] direction of NW loading. In all the cases, a gradual increase of the NW diameter has resulted in an asymptotic decrease of Young’s modulus consequently approaching that (Y b) of wurtzite-structured ZnO bulk along its [0 0 0 1] axis. The novelty of this study is that we combine the computation methods of quantum chemistry and molecular mechanics, while the majority of previous studies with the same aim have focused on the application of different classical molecular dynamical methods.

  18. A quantum chemical analysis of Zn and Sb doping and co-doping in SnO2

    Directory of Open Access Journals (Sweden)

    Luis Villamagua

    2017-10-01

    Full Text Available This work presents a quantum chemical study of Zn and Sb doping and co-doping in SnO2 carried out by a DFT+U method. The analysis has been developed by introducing three different modifications in the otherwise pure SnO2 system. In the first place, an oxygen vacancy was introduced within the crystal. Following, such a system was doped (separately by Zn or Sb impurities. Finally, the best energetic positions for both Zn and Sb atoms were simultaneously introduced within the lattice. Results of the simulations show that the confined charge that appeared due to the introduction of the oxygen vacancy interacts with the dopants atoms, being this interaction mostly responsible of the observed effects, i.e., EG shrinkage, F-centers formations, and magnetic momentum rise.

  19. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes.

    Science.gov (United States)

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M

    2016-06-08

    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

  20. Strong visible and near infrared photoluminescence from ZnO nanorods/nanowires grown on single layer graphene studied using sub-band gap excitation

    Science.gov (United States)

    Biroju, Ravi K.; Giri, P. K.

    2017-07-01

    Fabrication and optoelectronic applications of graphene based hybrid 2D-1D semiconductor nanostructures have gained tremendous research interest in recent times. Herein, we present a systematic study on the origin and evolution of strong broad band visible and near infrared (NIR) photoluminescence (PL) from vertical ZnO nanorods (NRs) and nanowires (NWs) grown on single layer graphene using both above band gap and sub-band gap optical excitations. High resolution field emission scanning electron microscopy and X-ray diffraction studies are carried out to reveal the morphology and crystalline quality of as-grown and annealed ZnO NRs/NWs on graphene. Room temperature PL studies reveal that besides the UV and visible PL bands, a new near-infrared (NIR) PL emission band appears in the range between 815 nm and 886 nm (1.40-1.52 eV). X-ray photoelectron spectroscopy studies revealed excess oxygen content and unreacted metallic Zn in the as-grown ZnO nanostructures, owing to the low temperature growth by a physical vapor deposition method. Post-growth annealing at 700 °C in the Ar gas ambient results in the enhanced intensity of both visible and NIR PL bands. On the other hand, subsequent high vacuum annealing at 700 °C results in a drastic reduction in the visible PL band and complete suppression of the NIR PL band. PL decay dynamics of green emission in Ar annealed samples show tri-exponential decay on the nanosecond timescale including a very slow decay component (time constant ˜604.5 ns). Based on these results, the NIR PL band comprising two peaks centered at ˜820 nm and ˜860 nm is tentatively assigned to neutral and negatively charged oxygen interstitial (Oi) defects in ZnO, detected experimentally for the first time. The evidence for oxygen induced trap states on the ZnO NW surface is further substantiated by the slow photocurrent response of graphene-ZnO NRs/NWs. These results are important for tunable light emission, photodetection, and other cutting edge

  1. Individual Zn2SnO4-sheathed ZnO heterostructure nanowires for efficient resistive switching memory controlled by interface states.

    Science.gov (United States)

    Cheng, Baochang; Ouyang, Zhiyong; Chen, Chuan; Xiao, Yanhe; Lei, Shuijin

    2013-11-19

    Resistive switching (RS) devices are widely believed as a promising candidate for next generation nonvolatile resistance random access memory. Here, Zn2SnO4-sheathed ZnO core/shell heterostructure nanowires were constructed through a polymeric sol-gel approach followed by post-annealing. The back-to-back bipolar RS properties were observed in the Ohmic contact two-terminal devices based on individual core/shell nanowires. With increasing bias to about 1.5 V, it changes from high-resistance states (HRS) to low-resistance states, and however, it can be restored to HRS by reverse bias. We propose a new mechanism, which is attributed to the injection of electrons into/from interfacial states, arising from the lattice mismatch at ZnO/Zn2SnO4 heterointerface. Upon applying negative/positive voltage at one end of devices, where interfacial states are filled/emptied, barrier will be eliminated/created, resulting into symmetric RS characteristics. The behavior of storage and removal charges demonstrates that the heterostructures have excellent properties for the application in resistance random access memory.

  2. Surface photovoltage characterization of a ZnO nanowire array/CdS quantum dot heterogeneous film and its application for photovoltaic devices.

    Science.gov (United States)

    Zhang, Yu; Xie, Tengfeng; Jiang, Tengfei; Wei, Xiao; Pang, Shan; Wang, Xi; Wang, Dejun

    2009-04-15

    ZnO nanowire (NWs) arrays coated with CdS quantum dots (QDs) were successfully fabricated with a chemical bath deposition process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD) have been utilized to characterize the samples. We have studied the processes of separation and recombination of the photo-generated charges in the visible region by surface photovoltage (SPV) and transient photovoltage (TPV) measurements. By controlling the amount of attached CdS QDs we found that the surface photovoltage characteristics change significantly. With a liquid electrolyte as the hole transport medium, the quantum dot sensitized nanowire solar cells (QDSSCs) exhibited short-circuit currents ranging from 0.8 to 2.6 mA cm(-2) and open-circuit voltages of 0.35-0.44 V when illuminated with light intensity 100 mW cm(-2). The relation between the performance of QDSSCs and their photovoltage characterization was also discussed.

  3. Controlled fabrication and photocatalytic properties of a three-dimensional ZnO nanowire/reduced graphene oxide/CdS heterostructure on carbon cloth.

    Science.gov (United States)

    Wang, Yajun; Wang, Fengmei; He, Jun

    2013-11-21

    A novel ZnO/reduced graphene oxide (RGO)/CdS heterostructure was successfully synthesized via a facile three-step solution method. RGO serves as an interlayer between ZnO nanowires and CdS quantum dots (QDs), which provides a high speed charge transfer channel, leading to an enhanced charge separation efficiency. Under UV light irradiation, the photocatalytic activity of the ZnO/RGO/CdS heterostructure is 4.0 times and 1.9 times as high as those of pure ZnO and ZnO/RGO, respectively. Under visible light irradiation, the ZnO/RGO/CdS heterostructure shows a dramatic visible light photocatalytic activity which is 2.3 times higher than that of the ZnO/CdS photocatalyst. The photocurrent of the ZnO/RGO/CdS heterostructure under UV light irradiation was greatly enhanced and a photocurrent under visible light irradiation was observed. The enhanced photocatalytic activity and the extended light adsorption spectrum originate from the type-II ZnO/CdS band alignment and the introduction of RGO as a charge mediator. Our results might open up a promising way to develop novel and highly efficient RGO-based heterostructure photocatalysts.

  4. ZnO nanorod/porous silicon nanowire hybrid structures as highly-sensitive NO2 gas sensors at room temperature.

    Science.gov (United States)

    Liao, Jiecui; Li, Zhengcao; Wang, Guojing; Chen, Chienhua; Lv, Shasha; Li, Mingyang

    2016-02-14

    ZnO nanorod/porous silicon nanowire (ZnO/PSiNW) hybrids with three different structures as highly sensitive NO2 gas sensors were obtained. PSiNWs were first synthesized by metal-assisted chemical etching, and then seeded in three different ways. After that ZnO nanorods were grown on the seeded surface of PSiNWs using a hydrothermal procedure. ZnO/PSiNW hybrids showed excellent gas sensing performance for various NO2 concentrations (5-50 ppm) at room temperature, and the electrical resistance change rate reached as high as 35.1% when responding to 50 ppm NO2. The distinct enhancement was mainly attributed to the faster carrier transportation after combination, the increase in gas sensing areas and the oxygen vacancy (VO) concentration. Moreover, the p-type gas sensing behavior was explained by the gas sensing mechanism and the effect of VO concentration on gas sensing properties was also discussed concerning the photoluminescence (PL) spectra performance.

  5. Hydrothermal treatment for the marked structural and optical quality improvement of ZnO nanowire arrays deposited on lightweight flexible substrates

    Science.gov (United States)

    Lupan, Oleg; Pauporté, Thierry

    2010-08-01

    ZnO nanowire arrays (NWs) have attracted great interest as the building blocks for emerging applications in new flexible and elastic electronic and optoelectronic devices (e.g. smart cards, light emitting diodes (LEDs), displays, etc.) with higher functionality. Since flexible plastic substrates (FPS) are important, soft post-growth treatments compatible with FPS must be found to significantly improve the properties of NWs deposited on it. We present an innovative low-temperature hydrothermal treatment in an autoclave to improve the structural and optical properties of ZnO NWs grown by electrochemical deposition at low temperature (80 °C) on transparent flexible polymer -based indium-tin-oxide (ITO) coated substrates. The layer characterizations by scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed the improvement of the wire surface smoothness and of their structural quality. The observed higher excitonic photoluminescence at 381 nm and the stronger optical phonon modes in the Raman spectra demonstrated the superior performance of the post-growth hydrothermal treatment compared to a conventional annealing at the same temperature. The presented results pave the way for the realization of new highly efficient ZnO-based optoelectronic devices on flexible plastic substrates or elastic foils.

  6. Visible light-sensitive APTES-bound ZnO nanowire toward a potent nanoinjector sensing biomolecules in a living cell

    Science.gov (United States)

    Lee, Jooran; Choi, Sunyoung; Bae, Seon Joo; Yoon, Seok Min; Choi, Joon Sig; Yoon, Minjoong

    2013-10-01

    Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon interaction with a complementary sequence-based double stranded (ds) DNA, whereas it is not significantly affected by non-complementary ds DNA. Further, the tip of a single APTES-ZnO NW can be inserted into the subcellular region of living HEK 293 cells without significant toxicity, and it can also detect the enhancement of the tip emission from subcellular regions with high spatial resolution. These results indicate that the single APTES-ZnO NW would be useful as a potent nanoinjector which can guide visible light into intracellular compartments of mammalian cells, and can also detect nanoscopic optical signal changes induced by interaction with the subcellular specific target biomolecules without separate optical probes.Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon

  7. Structural, electrical and magnetic properties of Sb-doped Pr{sub 2/3}Ba{sub 1/3}MnO{sub 3} perovskite manganites

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Vikram [Superconductivity Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India); Panwar, Neeraj [Superconductivity Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Bhalla, G.L. [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India); Agarwal, S.K. [Superconductivity Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)]. E-mail: agarwal@mail.nplindia.ernet.in

    2007-07-31

    We report here the electrical, magnetic and micro-structural features of the Sb-doped (nominally at Mn-sites) Pr{sub 2/3}Ba{sub 1/3}MnO{sub 3} perovskite manganites. Pristine material shows two insulator-metal (I-M) like transitions in the resistivity-temperature ({rho}-T) behaviour. While the higher temperature transition (T {sub P1}) at {approx}195 K is reminiscent of the usual metal-insulator transition, the lower temperature transition (T {sub P2}) at {approx}160 K has been ascribed to the grain boundary (GB) effects arising out of the ionic size mismatch between the ions present at the rare-earth site (Pr and Ba). With Sb doping at the Mn-site, both the resistivity peaks are seen to shift to lower temperatures. Room temperature resistivity and the peak values are also successively increasing with Sb doping. Scanning electron micrographs of the samples indicate a gradual increase in their grain sizes with Sb which indicates a gradual decrease in the GB density. The higher temperature insulator-metal transition (T {sub P1}) shift is explained on the basis of a competition between double-exchange and super-exchange mechanisms. The observed overall resistivity increase and the shift in the resistivity hump (T {sub P2}) with Sb are found related to the gradually decreasing GB density and the ensuing lattice strain increase at the grain boundaries. The intrinsic MR gets suppressed and the extrinsic MR gets enhanced with Sb doping. The observed low temperature resistivity upturn related to the localization of carriers, is also seen to increase with Sb.

  8. Synthesis and photoluminescence properties of ZnO nanohelices

    Science.gov (United States)

    Zhou, M. Y.; Qu, L. S.; Gao, H.

    2017-06-01

    Sb-doped zinc oxide nanohelices were synthesized on silicon substrates by chemical vapor deposition. The morphologies and structures of the samples have been investigated by XRD, SEM, and HR-TEM. The ZnO nanohelices have a single crystallinewurtzite structure. Its length is up to tens of micrometres as a whole. It grows in the direction of (0001). There are six sticks in each period of the helices, which grow al-ong six directions of the equivalent ≤ft . In addition, its growth mechanism is discussed. Optical properties of the nanohelices were demonstrated by Photo-luminescence (PL) spectra.

  9. The influence of Sb doping on the structural, optical and electrical properties of tin oxide thin film

    Science.gov (United States)

    Yusnidar, M. N.; Fauzia, V.; Handoko, D.; Hanum, L.

    2017-04-01

    Antimony-doped Tin Oxide (Sb:SnO2), shortened as ATO, has become more popular due to their great technological importance. ATO was considered as important transparent conducting material for optoelectronic devices and sensors application because of its unique and special characteristic such as high transparency in visible region, and high electrons concentration and mobility. In this study, the Sb:SnO2 thin film have been fabricated with low cost and simple ultrasonic spray pyrolysis method. SnO2 thin film was deposited with three different Sb concentrations namely 1, 2, and 3 wt%. The structural, morphological, optical and electrical properties of this film have been analyzed by using X-ray diffraction, scanning electron microscopy, UV-VIS and four point probe instruments. Based on the optical and electrical properties characterization, the best concentration of Sb doping was 2wt% because its transmittance was above 80% at all wavelength range measured, and the electrical resistivity was quite low, at 0.663 × 10-3 Ω cm.

  10. Visible light-sensitive APTES-bound ZnO nanowire toward a potent nanoinjector sensing biomolecules in a living cell.

    Science.gov (United States)

    Lee, Jooran; Choi, Sunyoung; Bae, Seon Joo; Yoon, Seok Min; Choi, Joon Sig; Yoon, Minjoong

    2013-11-07

    Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon interaction with a complementary sequence-based double stranded (ds) DNA, whereas it is not significantly affected by non-complementary ds DNA. Further, the tip of a single APTES-ZnO NW can be inserted into the subcellular region of living HEK 293 cells without significant toxicity, and it can also detect the enhancement of the tip emission from subcellular regions with high spatial resolution. These results indicate that the single APTES-ZnO NW would be useful as a potent nanoinjector which can guide visible light into intracellular compartments of mammalian cells, and can also detect nanoscopic optical signal changes induced by interaction with the subcellular specific target biomolecules without separate optical probes.

  11. Preparation of SiO2 Nanotubes with Controllable Inner/Outer Diameter and Length Using Hydrothermally Grown ZnO Nanowires as Templates

    Science.gov (United States)

    Kuo, Der-Ming; Wang, Shui-Jinn; Uang, Kai-Ming; Chen, Tron-Min; Tsai, Wei-Chih; Hsu, Wen-I.; Lee, Wei-Chi; Wang, Pei-Ren; Tseng, Chih-Ren

    2010-04-01

    Through the deposition of a thin SiO2 film to sheathe hydrothermally grown (HTG) ZnO nanowires (ZnO-NWs), unveiling their top portion, and then selectively removing ZnO-NWs by wet chemical etching, SiO2 nanotubes (SiO2-NTs) with controllable inner/outer diameters and lengths were fabricated. The prepared SiO2-NTs with average inner/outer diameters and lengths of approximately 200/300 nm and 1.5 µm, respectively, exhibited a superior transmittance of 92% in the visible light spectrum. The surface roughened process using SiO2-NTs on vertical-structure GaN light-emitting diodes (VLEDs) showed additional light output improvement of about 11.6% at 350 mA and 10% at 750 mA, compared with those of VLEDs with ZnO-NWs, suggesting the effectiveness and promising applications of the proposed SiO2-NTs in optics and optoelectronics devices.

  12. Vertical p-type Cu-doped ZnO/n-type ZnO homojunction nanowire-based ultraviolet photodetector by the furnace system with hotwire assistance.

    Science.gov (United States)

    Hsu, Cheng-Liang; Gao, Yi-Dian; Chen, You-Syuan; Hsueh, Ting-Jen

    2014-03-26

    Vertical p-ZnO:Cu/n-ZnO homojunction nanowires (NWs) and whole ZnO:Cu NWs were synthesized on a ZnO thin film/glass substrate by a furnace at 600 °C with 1700 °C hotwire assistance. According to the ZnO:Cu NW investigation, the energy-dispersive X-ray (EDX) spectrum indicates that the Cu content is 3.01 atomic %. The X-ray diffraction (XRD) peaks of ZnO:Cu NWs shift toward larger angles with increasing amounts of doped Cu. The Cu dopant enhanced the photoluminescence (PL) green-band peak and decreased the conductivity of the NWs, as measured by I-V. The gas sensing measurement and Hall effect verified that all ZnO:Cu NWs were p-type. In this study, transmission electron microscopy (TEM) and EDX mapping images revealed that the majority of the Cu element is located at the top of the p-ZnO:Cu/n-ZnO NW. The high-resolution transmission electron microscopy (HRTEM) image of the p-ZnO:Cu region shows that the NWs are [0001] growth-oriented, with lateral surfaces enclosed by (1̅101) planes. The I-V curve of p-ZnO:Cu/n-ZnO NWs displays the characteristics of normal rectifying diodes. The photocurrent under ultraviolet (UV) exposure was around 6 times higher than the dark current at the reverse bias of -5 V.

  13. Growth of novel ZnO nanohelices modified by SiO{sub 2}-sheathed ZnO discs

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H [Department of Physics, Harbin Institute of Technology, PO Box 3025, Harbin 150080 (China); Zhang, X T [Department of Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Zhou, M Y [Department of Physics, Harbin Normal University, Harbin 150080 (China); Zhang, Z G [Department of Physics, Harbin Institute of Technology, PO Box 3025, Harbin 150080 (China); Wang, X Z [Department of Physics, Harbin Normal University, Harbin 150080 (China)

    2007-02-14

    Disc-modified nanohelices (DNHs) of ZnO were synthesized by thermal evaporation. The ZnO DNHs are constructed by nanowires which are regularly attached with discs. The axis of the DNH structure is along the ZnO[0001] direction. The pitch distance, the mean diameter, and the thickness of the nanowires are uniform for each ZnO DNH. Within one period there are 12 discs symmetrically attached on the surfaces of the nanowires. The discs are composed of nanometre-sized ZnO crystal cores and amorphous SiO{sub 2} shells. The mechanism of formation of the nanostructures is also discussed.

  14. Ferroelectric-to-relaxor crossover in Sb doped PLZT x/52/48 (2 ≤ x ≤ 16 piezoelectric ceramics

    Directory of Open Access Journals (Sweden)

    Sheng Tong

    2014-03-01

    Full Text Available Dielectric behavior and diffuse phase transition have been investigated in Sb doped lead lanthanum zirconate titanate (PLZT ceramics to understand the role of La and Sb in ferroelectric-to-relaxor crossover. Rayleigh and Curie–Weiss type law fittings show that the La substitution gradually transforms the PLZTs from ferroelectric to relaxor, while Sb dopants weaken the diffuseness and dielectric dispersion. Vogel–Fulcher model reveals that the samples at high La concentration are fully in relaxor state comparable to the undoped PLZTs.

  15. CdTe Nanocrystal Hetero-Junction Solar Cells with High Open Circuit Voltage Based on Sb-doped TiO₂ Electron Acceptor Materials.

    Science.gov (United States)

    Li, Miaozi; Liu, Xinyan; Wen, Shiya; Liu, Songwei; Heng, Jingxuan; Qin, Donghuan; Hou, Lintao; Wu, Hongbin; Xu, Wei; Huang, Wenbo

    2017-05-03

    We propose Sb-doped TiO₂ as electron acceptor material for depleted CdTe nanocrystal (NC) hetero-junction solar cells. Novel devices with the architecture of FTO/ZnO/Sb:TiO₂/CdTe/Au based on CdTe NC and TiO₂ precursor are fabricated by rational ambient solution process. By introducing TiO₂ with dopant concentration, we are able to tailor the optoelectronic properties of NC solar cells. Our novel devices demonstrate a very high open circuit voltage of 0.74 V, which is the highest V oc reported for any CdTe NC based solar cells. The power conversion efficiency (PCE) of solar cells increases with the increase of Sb-doped content from 1% to 3%, then decreases almost linearly with further increase of Sb content due to the recombination effect. The champion device shows J sc , V oc , FF, and PCE of 14.65 mA/cm², 0.70 V, 34.44, and 3.53% respectively, which is prospective for solution processed NC solar cells with high V oc .

  16. Failure mechanisms and electromechanical coupling in semiconducting nanowires

    Directory of Open Access Journals (Sweden)

    Peng B.

    2010-06-01

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

  17. Liquid crystal alignment on zinc oxide nanowire arrays for LCDs applications.

    Science.gov (United States)

    Chen, Mu-Zhe; Chen, Wei-Sheng; Jeng, Shie-Chang; Yang, Sheng-Hsiung; Chung, Yueh-Feng

    2013-12-02

    The zinc oxide (ZnO) nanowire arrays on the indium tin oxide (ITO) glass substrates were fabricated by using the two-step hydrothermal method. A high transmittance ~92% of ZnO nanowire arrays on ITO substrate in the visible region was obtained. It was observed that the liquid crystal (LC) directors were aligned vertically to the (ZnO) nanowire arrays. The properties of ZnO nanowire arrays as vertical liquid crystal (LC) alignment layers and their applications for hybrid-aligned nematic LC modes were investigated in this work.

  18. Efficiency Investigation of Dye-Sensitized Solar Cells Based on the Zinc Oxide Nanowires

    OpenAIRE

    Ahmad Afifi; Mohammad Kazem Tabatabaei

    2014-01-01

    In this paper, we synthesized ZnO nanowires in dye sensitized solar cells. The nanowires have been fabricated using fast-microwave-hydrothermal process.We verify the effects of different lengths of ZnO nanowires on efficiency and absorptionofdye sensitized solar cells. J–V curves of the fabricated ZnO nanowire-based mercurochrome-sensitized solar cellsindicated that the short-circuit current density wouldincrease with increasing the length of nanowires.We also fabricate more efficient N719-se...

  19. Biofunctionalization of zinc oxide nanowires for DNA sensory applications

    Directory of Open Access Journals (Sweden)

    Rudolph Bettina

    2011-01-01

    Full Text Available Abstract We report on the biofunctionalization of zinc oxide nanowires for the attachment of DNA target molecules on the nanowire surface. With the organosilane glycidyloxypropyltrimethoxysilane acting as a bifunctional linker, amino-modified capture molecule oligonucleotides have been immobilized on the nanowire surface. The dye-marked DNA molecules were detected via fluorescence microscopy, and our results reveal a successful attachment of DNA capture molecules onto the nanowire surface. The electrical field effect induced by the negatively charged attached DNA molecules should be able to control the electrical properties of the nanowires and gives way to a ZnO nanowire-based biosensing device.

  20. Effect of Ni and Au ion irradiations on structural and optical properties of nanocrystalline Sb-doped SnO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mir, Feroz A. [University of Kashmir, University Science Instrumentation Centre, Srinagar, J and K (India); Batoo, Khalid Mujasam [King Saud University, King Abdullah Institute for Nanotechnology, Riyadh (Saudi Arabia)

    2016-04-15

    The effect of swift heavy ion irradiations on the structural and optical properties of 6 % Sb-doped SnO{sub 2} thin films deposited on quartz substrate by electron beam evaporation technique is presented. Two ion species Ni and Au with energy 120 MeV and fluence of 1 x 10{sup 13} ion/cm{sup 2} were used. These films were characterized by X-ray diffraction, atomic force microscope, UV-visible and micro-Raman spectroscopy. From structural analysis, these films exhibit tetragonal rutile structure and retain it even after irradiation. The ion irradiations have shown improvement in the structural properties, such as increase in grain size and decrease in the lattice strain. Raman study also indicates enhancement in quality of crystal structure after irradiations. The grain growth after ion interaction is also observed by atomic force microscope study. Further, a variation in optical band gap and reduction in disorder is observed after irradiation. Other parameters such as Urbach tails energy and steepness parameter are obtained from optical data. The overall observed physical properties show a significant improvement after irradiation. A good correspondence between structures with its various properties can be seen. (orig.)

  1. Materials and Devices Research of PPV-ZnO Nanowires for Heterojunction Solar Cells

    OpenAIRE

    Zhang Xiao-Zhou; Jian Xi-Gao; Zu Li-Wu

    2012-01-01

    Bulk heterojunction photovoltaic devices, which use the conjugated polymer poly(2-methoxyl-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) as the electron donor and crystalline ZnO nanowires as the electron acceptor, have been studied in this work. The ZnO nanowires were prepared through a chemical vapor deposition mechanism. The dissolved MEH-PPV polymer was spin-coated onto the nanowires. The scanning electron microscope images showed that the ZnO nanowires were covered with a single ...

  2. Wide band gap semiconductor nanowires for optical devices 1 low-dimensionality related effects and growth

    CERN Document Server

    Consonni , Vincent

    2014-01-01

    GaN and ZnO nanowires can by grown using a wide variety of methods from physical vapor deposition to wet chemistry for optical devices. This book starts by presenting the similarities and differences between GaN and ZnO materials, as well as the assets and current limitations of nanowires for their use in optical devices, including feasibility and perspectives. It then focuses on the nucleation and growth mechanismsof ZnO and GaN nanowires, grown by various chemical and physical methods. Finally, it describes the formation of nanowire heterostructures applied to optical devices.

  3. Pyrolytically grown indium sulfide sensitized zinc oxide nanowires for solar water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Komurcu, Pelin; Can, Emre Kaan; Aydin, Erkan; Semiz, Levent [Micro and Nanotechnology Graduate Program, TOBB University of Economics and Technology, 06560 Ankara (Turkey); Gurol, Alp Eren; Alkan, Fatma Merve [Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, 06560 Ankara (Turkey); Sankir, Mehmet; Sankir, Nurdan Demirci [Micro and Nanotechnology Graduate Program, TOBB University of Economics and Technology, 06560 Ankara (Turkey); Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, 06560 Ankara (Turkey)

    2015-11-15

    Zinc oxide (ZnO) nanowires, sensitized with spray pyrolyzed indium sulfide, were obtained by chemical bath deposition. The XRD analysis indicated dominant evolution of hexagonal ZnO phase. Significant gain in photoelectrochemical current using ZnO nanowires is largely accountable to enhancement of the visible light absorption and the formation of heterostructure. The maximum photoconversion efficiency of 2.77% was calculated for the indium sulfide sensitized ZnO nanowire photoelectrodes. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. P-Cu2O/n-ZnO nanowires on ITO glass for solar cells.

    Science.gov (United States)

    Zhang, Jin; Que, Wenxiu; Zhong, Peng; Zhu, Gangqiang

    2010-11-01

    In this paper, the fabrication and characterization of a heterojunction solar cell based on p-Cu2O/n-ZnO nanowires on ITO glass are presented. ZnO aligned nanocrystal seed layer is firstly prepared by RF magnetron sputtering technique, and then vertical ZnO nanowire arrays with an acicular crystal structure are obtained by using a chemical bath deposition processing. The results indicate that the ZnO nanowires with a diameter of about 50 nm and 500 nm in length can be easily obtained. The absorption and transmittance of the ZnO nanowires are studied. It is also noted that the Cu2O can fill well into the space between ZnO nanowires by an electrodeposition process. Furthermore, the effect of the Cu2O orientation on the cell performance is also presented.

  5. Optimization of CVD parameters for long ZnO NWs grown on ITO ...

    Indian Academy of Sciences (India)

    ZnO nanowires (NWs) were investigated. Typical ZnO NWs as a single crystal grown on indium tin oxide (ITO)- coated glass substrate were successfully synthesized. First, the conducted side of ITO–glass substrate was coated with zinc acetate dihydrate to form seed layer of ZnO nanocrystals. Double zone tube furnace ...

  6. The impact of nanocontact on nanowire based nanoelectronics.

    Science.gov (United States)

    Lin, Yen-Fu; Jian, Wen-Bin

    2008-10-01

    Nanowire-based nanoelectronic devices will be innovative electronic building blocks from bottom up. The reduced nanocontact area of nanowire devices magnifies the contribution of contact electrical properties. Although a lot of two-contact-based ZnO nanoelectronics have been demonstrated, the electrical properties bringing either from the nanocontacts or from the nanowires have not been considered yet. High quality ZnO nanowires with a small deviation and an average diameter of 38 nm were synthesized to fabricate more than thirty nanowire devices. According to temperature behaviors of current-voltage curves and resistances, the devices could be grouped into three types. Type I devices expose thermally activated transport in ZnO nanowires and they could be considered as two Ohmic nanocontacts of the Ti electrode contacting directly on the nanowire. For those nanowire devices having a high resistance at room temperatures, they can be fitted accurately with the thermionic-emission theory and classified into type II and III devices according to their rectifying and symmetrical current-voltage behaviors. The type II device has only one deteriorated nanocontact and the other one Ohmic contact on single ZnO nanowire. An insulating oxide layer with thickness less than 20 nm should be introduced to describe electron hopping in the nanocontacts, so as to signalize one- and high-dimensional hopping conduction in type II and III devices.

  7. Effect of an Sb-Doped SnO2 Support on the CO-Tolerance of Pt2Ru3 Nanocatalysts for Residential Fuel Cells

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Ogihara

    2016-09-01

    Full Text Available We prepared monodisperse Pt2Ru3 nanoparticles supported on carbon black and Sb-doped SnO2 (denoted as Pt2Ru3/CB and Pt2Ru3/Sb-SnO2 with identical alloy composition and particle size distribution by the nanocapsule method. The activities for the hydrogen oxidation reaction (HOR of these anode catalysts were examined in H2-saturated 0.1 M HClO4 solution in both the presence and absence of carbon monoxide by use of a channel flow electrode at 70 °C. It was found that the CO-tolerant HOR mass activity at 0.02 V versus a reversible hydrogen electrode (RHE on the Pt2Ru3/Sb-SnO2 electrode was higher than that at the Pt2Ru3/CB electrode in 0.1 M HClO4 solution saturated with 1000 ppm CO (H2-balance. The CO tolerance mechanism of these catalysts was investigated by in situ attenuated total reflection Fourier transform infrared reflection-adsorption spectroscopy (ATR-FTIRAS in 1% CO/H2-saturated 0.1 M HClO4 solution at 60 °C. It was found, for the Pt2Ru3/Sb-SnO2 catalyst, that the band intensity of CO linearly adsorbed (COL at step/edge sites was suppressed, together with a blueshift of the COL peak at terrace sites. On this surface, the HOR active sites were concluded to be more available than those on the CB-supported catalyst surface. The observed changes in the adsorption states of CO can be ascribed to an electronic modification effect by the Sb-SnO2 support.

  8. Electrical and optical properties of Sb-doped BaSnO{sub 3} epitaxial films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu Qinzhuang; Dai Jianming; Liu Zhongliang; Zhang Xiaobo; Zhu Guangping; Ding Guohua, E-mail: qzliu@mail.ustc.edu.c [Department of Physics, Huaibei Normal University, Huaibei 235000 (China)

    2010-11-17

    In this paper we report the structural, electrical and optical properties of epitaxial Ba(Sb{sub x}Sn{sub 1-x})O{sub 3} (x = 0-0.30) (BSSO) films grown on SrTiO{sub 3}(0 0 1) substrates by the pulsed laser deposition method. The investigation reveals that the transport and optical characteristics of BSSO films depend very sensitively on the Sb-doping content. Temperature-dependent resistivity measurements show that at low Sb contents (x = 0.03, 0.07) the metal-semiconductor transition occurs at 150 K and 80 K, respectively, and the semiconductor behaviour appears in high doped (x = 0.15, 0.30) films. The transmittance decreases significantly from about 80% to nearly zero in the visible region and the optical band gap shifts from 3.48 to 4.0 eV with increasing Sb content in the films. The lowest room-temperature resistivity of 2.43 m{Omega} cm with carrier density and mobility of 1.65 x 10{sup 21} cm{sup -3} and 1.75 cm{sup 2} V{sup -1} s{sup -1} was obtained in the films with doping at x = 0.07. By employing them as bottom electrodes we have fabricated transparent Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} ferroelectric capacitors showing square polarization-electric field hysteresis loops, indicating that these perovskite-type BSSO films at low doping can be potentially used in transparent devices especially based on all-perovskite heterostructures.

  9. Development of gas sensors using ZnO nanostructures

    Indian Academy of Sciences (India)

    Different ZnO nanostructures such as nanowires, nanobelts and tetrapods have been grown and used for preparation of thick film (with random grain boundaries) as well as isolated nanowire/nanobelt gas sensors. Sensitivity of different type of sensors has been studied to H2S and NO gases. The results show that the ...

  10. ZnO nanostructures and their applications

    CERN Document Server

    Xiaowei, Sun

    2011-01-01

    This book focuses on the various functional properties and potential applications of one-dimensional ZnO nanostructures, from basic principles to our most recent discoveries. It comprises experimental analysis of various properties of ZnO nanostructures, preparation techniques, research methods, and some promising applications. The areas of focus include ZnO-based gas/biochemical sensing devices, field emitters, solar cells, light-emitting diodes, e-papers, and single-nanowire-based transistors.

  11. ZnO-nanowires/PANI inorganic/organic heterostructure light-emitting diode.

    Science.gov (United States)

    He, Ying; Wang, Jun-an; Zhang, Wenfei; Song, Jizhong; Pei, Changlong; Chen, Xiaoban

    2010-11-01

    In this paper, we report a flexible inorganic/organic heterostructure light-emitting diode, in which inorganic ZnO nanowires are the optically active components and organic polyaniline (PANI) is the hole-transporting layer. The fabrication of the hybrid LED is as follows, the ordered single-crystalline ZnO nanowires were uniformly distributed on flexible polyethylene terephthalate (PET)-based indium-tin-oxide-coated substrates by our polymer-assisted growth method, and proper materials were chosen as electrode and carrier. In this construction, an array of ZnO nanowires grown on PET substrate is successfully embedded in a polyaniline thin film. The performance of the hybrid device of organic-inorganic hetero-junction of ITO/(ZnO nanowires-PANI) for LED application in the blue and UV ranges are investigated, and tunable electroluminescence has been demonstrated by contacting the upper tips of ZnO nanowires and the PET substrate. The effect of surface capping with polyvinyl alcohol (PANI) on the photocarrier relaxation of the aqueous chemically grown ZnO nanowires has been investigated. The photoluminescence spectrum shows an enhanced ultraviolet emission and reduced defect-related emission in the capped ZnO NWs compared to bare ZnO. The results of our study may offer a fundamental understanding in the field of inorganic/organic heterostructure light-emitting diode, which may be useful for potential applications of hybrid ZnO nanowires with conductive polymers.

  12. TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

    Science.gov (United States)

    Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan; Xie, Xi

    2017-12-01

    Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.

  13. Growth of vertically aligned ZnO nanorods using textured ZnO films

    Directory of Open Access Journals (Sweden)

    Meléndrez Manuel

    2011-01-01

    Full Text Available Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100 substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.

  14. Growth of vertically aligned ZnO nanorods using textured ZnO films.

    Science.gov (United States)

    Solís-Pomar, Francisco; Martínez, Eduardo; Meléndrez, Manuel F; Pérez-Tijerina, Eduardo

    2011-09-07

    A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS: 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.).

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

    Science.gov (United States)

    Nimmatoori, Pramod

    2009-12-01

    time, temperature, SiH4 partial pressure and wire diameter and discussed in the context of the literature. The wire growth rate was found to increase with wire diameter in agreement with a size-related effect known as the Gibbs-Thomson effect. Subsequently, the effect of P and Sb doping on the growth rate and structural properties of Si nanowires was investigated. A reduction in wire growth rate was observed upon doping, which was pronounced in case of Sb doping, ascribable to P/Sb segregation at the vapor-liquid interface (catalyst surface) and the liquid-solid interface (growth front) that in turn reduces Si incorporation at these interfaces. The second part of thesis was focused on the Si1-xGe x alloy nanowires. The effect of wire diameter and growth conditions on the interfacial abruptness of Si/Si1-xGex heterostructure nanowires was examined. Abrupt interfaces were obtained at smaller wire diameters. However, the growth temperature wasn't found to have much impact on the interfacial abruptness. These results were explained in terms of catalyst effects on the interfacial abruptness. The remaining part of the study was focused on the effect of growth conditions on the growth rate of Si1-x Gex nanowires. It was found that the Si incorporation mechanism was different between Si and Si1-xGex nanowire growth which was ascribed to changes in the gas phase or catalyst composition that can impact the SiH4 decomposition kinetics at the catalyst surface (vapor-liquid interface) and/or Si incorporation at the growth front (liquid-solid interface).

  16. Investigation on the Tunable-Length Zinc Oxide Nanowire Arrays for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Shou-Yi Kuo

    2014-01-01

    Full Text Available We had successfully fabricated ZnO-based nanowires by vapor transport method in the furnace tube. ZnO nanowire arrays grown in 600°C for 30 minutes, 60 minutes, 90 minutes, and 120 minutes had applied to the dye-sensitized solar cells. The dye loading is proportional to the total equivalent surface area of ZnO nanowire arrays in the cells and plays an important role in improving power conversion efficiency. The highest efficiency was observed in DSSC sample with ZnO nanowires grown for 90 minutes, which had the largest equivalent surface area and also the highest dye loading. According to our experimental results, the enhancement in power conversion efficiency is attributed to the higher light harvesting and reduction of carrier recombination. In addition, ZnO nanowires also contribute to the photocurrent in the UV region.

  17. Synthesis and characterization of p-n homojunction-containing zinc oxide nanowires

    Science.gov (United States)

    Li, Guohua; Sundararajan, Abhishek; Mouti, Anas; Chang, Yao-Jen; Lupini, Andrew R.; Pennycook, Stephen J.; Strachan, Douglas R.; Guiton, Beth S.

    2013-02-01

    We illustrate a simple method to synthesize highly ordered ZnO axial p-n homojunction-containing nanowires using a low temperature method, and on a variety of substrates. X-ray diffraction, scanning transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy are used to reveal high quality single-crystalline wires with a [001] growth direction. The study of electrical transport through a single nanowire based device and cathodoluminescence via scanning transmission electron microscopy demonstrates that an axial p-n junction exists within each ZnO nanowire. This represents the first low temperature synthesis of axial p-n homojunction-containing ZnO nanowires with uniform and controllable diameters.We illustrate a simple method to synthesize highly ordered ZnO axial p-n homojunction-containing nanowires using a low temperature method, and on a variety of substrates. X-ray diffraction, scanning transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy are used to reveal high quality single-crystalline wires with a [001] growth direction. The study of electrical transport through a single nanowire based device and cathodoluminescence via scanning transmission electron microscopy demonstrates that an axial p-n junction exists within each ZnO nanowire. This represents the first low temperature synthesis of axial p-n homojunction-containing ZnO nanowires with uniform and controllable diameters. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr31639d

  18. Single-crystalline zinc oxide nanowires as photoanode material for dye-sensitized solar cells.

    Science.gov (United States)

    Ho, Shu-Te; Hsiao, Ching-Lun; Lin, Hsin-Yu; Chen, Hsiang-An; Wang, Chiu-Yen; Lin, Heh-Nan

    2010-10-01

    This study reports the use of single-crystalline and well-aligned ZnO nanowires as photoanode material for dye-sensitized solar cells. The ZnO nanowires are grown on fluorine-doped tin oxide coated glass substrates without catalysts by thermal evaporation. In spite of low roughness factors of around 25 for the nanowire photoanodes, the fabricated solar cells yield power conversion efficiencies of around 1.3% under AM 1.5G (100 mW cm-2) illumination. Moreover, fill factors of around 0.5 have been achieved and are relatively high when compared with reported values from ZnO nanowire photoanodes. The results reveal the advantage of using single-crystalline nanowires as photoanode material and provide clues for the advancement of nanowire based dye-sensitized solar cells.

  19. Rapid Hydrothermal Synthesis of Zinc Oxide Nanowires by Annealing Methods on Seed Layers

    Directory of Open Access Journals (Sweden)

    Jang Bo Shim

    2011-01-01

    Full Text Available Well-aligned zinc oxide (ZnO nanowire arrays were successfully synthesized on a glass substrate using the rapid microwave heating process. The ZnO seed layers were produced by spinning the precursor solutions onto the substrate. Among coatings, the ZnO seed layers were annealed at 100°C for 5 minutes to ensure particle adhesion to the glass surface in air, nitrogen, and vacuum atmospheres. The annealing treatment of the ZnO seed layer was most important for achieving the high quality of ZnO nanowire arrays as ZnO seed nanoparticles of larger than 30 nm in diameter evolve into ZnO nanowire arrays. Transmission electron microscopy analysis revealed a single-crystalline lattice of the ZnO nanowires. Because of their low power (140 W, low operating temperatures (90°C, easy fabrication (variable microwave sintering system, and low cost (90% cost reduction compared with gas condensation methods, high quality ZnO nanowires created with the rapid microwave heating process show great promise for use in flexible solar cells and flexible display devices.

  20. Microwave absorption properties and the isotropic antenna mechanism of ZnO nanotrees

    Science.gov (United States)

    Zhuo, R. F.; Qiao, L.; Feng, H. T.; Chen, J. T.; Yan, D.; Wu, Z. G.; Yan, P. X.

    2008-11-01

    In this paper, ZnO nanowires and ZnO nanotrees have been prepared and their microwave absorption properties have been investigated in detail. Complex permittivity and permeability of the ZnO nanostructures and paraffin composites have been measured in a frequency of 0.1-18 GHz. Excellent microwave absorption performances have been observed in ZnO nanotree composite compared to ZnO nanowire composite, and the maximum absorption is enhanced as the concentration of the nanotrees increases in the composite. The value of minimum reflection loss for the composites with 60 vol % ZnO nanotrees is -58 dB at 4.2 GHz with a thickness of 4.0 mm. Such strong absorption is attributed to the unique isotropic antenna morphology of the ZnO nanotrees in the composite.

  1. Anodized ZnO nanostructures for photoelectrochemical water splitting

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-01

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

  2. Organic Nanowires

    DEFF Research Database (Denmark)

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

    Single crystalline nanowires from fluorescing organic molecules like para-phenylenes or thiophenes are supposed to become key elements in future integrated optoelectronic devices [1]. For a sophisticated design of devices based on nanowires the basic principles of the nanowire formation have...

  3. Synthesis and Characterization of ZnO/ZnS Core/Shell Nanowires

    Directory of Open Access Journals (Sweden)

    Taher Ghrib

    2014-01-01

    Full Text Available ZnO nanowires of approximately 3 µm length and 200 nm diameter are prepared and implanted vertically on substrate glass which is coated with thin layer of ITO which is too covered with bulk ZnO thin layer via electrodeposition process by cyclic voltammetry-chronoamperometry and with a chemical process that is described later; we have synthesized a ZnS nanolayer. ZnO/ZnS core/shell nanowires are formed by ZnO nanowires core surrounded by a very thin layer of porous ZnS shell principally constituted with a crystal which is about 15–20 nm in diameter. In the method, ZnS nanoparticles were prepared by reaction of ZnO nanowires with Na2S in aqueous solution at low temperature and also we have discussed the growth mechanism of ZnO/ZnS nanowires. The morphology, structure, and composition of the obtained nanostructures were obtained by using X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and X-ray photoelectron spectroscopy (XPS. For the structure, SEM and XRD measurements indicated that the as-grown ZnO nanowires microscale was of hexagonal wurtzite phase with a high crystalline quality, and TEM shows that the ZnS is uniformly distributed on the surface of the ZnO nanowires.

  4. Growth and luminescence characterization of large-scale zinc oxide nanowires

    CERN Document Server

    Dai, L; Wang, W J; Zhou, T; Hu, B Q

    2003-01-01

    Large-scale zinc oxide (ZnO) nanowires were grown via a simple chemical reaction involving water vapour. Electron microscopy observations reveal that the ZnO nanowires are single crystalline and grow along the c-axis ([001]) direction. Room temperature photoluminescence measurements show a striking blue emission at 466 nm along with two other emissions in the ultraviolet and yellow regions. Annealing treatment of the as-grown ZnO nanowires results in an apparent reduction of the intensity of the blue emission, which indicates that the blue emission might be originating from the oxygen or zinc defects generated in the process of growth of the ZnO nanowires.

  5. Zinc oxide nanowire interphase for enhanced interfacial strength in lightweight polymer fiber composites.

    Science.gov (United States)

    Ehlert, Gregory J; Sodano, Henry A

    2009-08-01

    A novel functionalization method for aramid fibers is developed to enhance the bonding of a ZnO nanowire interphase grown on the fiber surface for interfacial strength enhancement. The nanowire interphase functionally grades the typically discrete interface and reduces the stress concentration between the fiber and matrix. The functionalization process is developed to improve the bonding between the ZnO nanowires and the aramid fiber and is validated through Fourier transform IR and X-ray photoelectron spectroscopy studies. Mechanical testing shows significant improvement in the interfacial shear strength with no decrease in the base fiber strength. This is the only technique found in the literature for the growth of a nanowire interphase on polymer fibers for structural enhancement without degrading the in-plane properties of the bulk composite. Furthermore, it is firmly shown that the functionalization process is a necessary condition for enhanced interfacial strength, demonstrating that ZnO nanowires strongly interact with carboxylic acid functional groups.

  6. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  7. Photoluminescence and gas sensing study of nanostructured pure and Sn doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Navale, Shalaka C. [Physical and Materials Chemistry Division, National Chemical Laboratory, Pune-411008 (India); DST Unit on Nanoscience, Department of Physics, University of Pune, Pune-411008 (India); Mulla, I.S., E-mail: is.mulla@ncl.res.in [Physical and Materials Chemistry Division, National Chemical Laboratory, Pune-411008 (India)

    2009-05-05

    The nanostructured pure and Sn doped ZnO have been synthesized by the thermal evaporation technique. The influence of Sn on the morphology and structure is investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis techniques. The SEM images indicate change in the growth pattern from nanowires of pure ZnO to tetrapods for Sn doped ZnO. Pure ZnO nanowires exhibit selective response towards acetone vapors while on Sn doping the response decreases. The non-stiochiometry and the morphology of ZnO are probably responsible for such a difference in gas response. However increase in temperature doesn't improve the sensing behavior. The photoluminiscence (PL) studies reveal UV emission in pure ZnO which shifts to green emission on doping of Sn.

  8. Enhanced field emission of ZnO nanoneedle arrays via solution etching at room temperature

    DEFF Research Database (Denmark)

    Ma, Huanming; Qin, Zhiwei; Wang, Zaide

    2017-01-01

    ZnO nanoneedle arrays (ZnO nns) were synthesized by a facile two-step solution-phase method based on the etching of pre-synthesized ZnO nanowire arrays (ZnO nws) with flat ends at room temperature. Field emission measurement results showed that the turn-on electronic fields of ZnO nns and nws wer...... 2.7 and 5.3 V μm−1 at a current density of 10 μA cm−2, and the field enhancement factors were 4939.3 for ZnO nns and 1423.6 for ZnO nws. The enhanced field emission properties in ZnO nns were ascribed to the sharp tip geometry....

  9. Synthesis and Characterization of ZnO/ZnS Core/Shell Nanowires

    National Research Council Canada - National Science Library

    Ghrib, Taher; Abdullah Al-Messiere, Muneera; Lafi Al-Otaibi, Amal

    2014-01-01

    ...; we have synthesized a ZnS nanolayer. ZnO/ZnS core/shell nanowires are formed by ZnO nanowires core surrounded by a very thin layer of porous ZnS shell principally constituted with a crystal which is about 15-20 nm in diameter...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-15

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

  11. TEM Study of the Growth Mechanism, Phase Transformation, and Core/shell Structure of Semiconductor Nanowires

    Science.gov (United States)

    Wong, Tai Lun

    instantly due to high temperature annealing. Furthermore, the phase transformation preferred to begin at the defect and bending region of the nanowires, as the nickel can easily diffuse through the native oxide on the Si nanowires rather than the other regions. By removing the native oxide on the Si nanowires using HF, the temperature required for the phase transformation was decreased significantly. However, without the native oxide, the phase transformation became a multi-site nucleation process, and the nanowire became a polycrystalline and multiphase nickel silicide nanowires after the reaction. A simple and effective method is developed for fabricating high-quality vertically aligned ZnO nanowire arrays using carbonized photoresists. ZnO nanowires fabricated by this method show excellent alignment, crystal quality, and optical properties that are independent of the substrates. We further fabricated vertically aligned ZnO/a-Si core-shell heterojunction nanowire arrays through direct chemical vapor deposition (CVD) of amorphous silicon on ZnO nanowire surfaces. The thickness of the a-Si shells linearly increases with deposition time and the deposition rate was about 5nm/min at 530 °C. Since the Si shell is p-type and the ZnO core is intrinsic n-type semiconductors, the ZnO/ amorphous silicon core-shell nanowires naturally formed hetero p-n junctions. The antireflection property of the ZnO/amorphous silicon core-shell nanowires is dramatically enhanced due to the rough interface between the ZnO and amorphous silicon. Additionally, the intensity of the Photoluminescence spectrum of ZnO/amorphous silicon core-shell structures is decreasing with the thickness of the amorphous silicon shell increases.

  12. Sound-driven piezoelectric nanowire-based nanogenerators

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Seung Nam; Kim, Seong Min; Kim, Hyun Jin; Park, Young Jun; Kim, Jong Min [Frontier Research Laboratory, Samsung Advanced Institute of Technology, Yongin, Gyeonggi, 446-712 (Korea, Republic of); Seo, Ju-Seok; Kim, Sang-Woo [School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Center for Human Interface Nanotechnology (HINT), Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)

    2010-11-09

    Sound-driven power generation using nanogenerators based on piezoelectric ZnO nanowires has been demonstrated. Systematic investigations on the power-generating performance of sound-driven nanogenerators clearly support that the measured output voltage originated from the sound-driven nanogenerator. This study shows that sound can be one of promising energy sources when using highly efficient nanogenerators based on piezoelectric nanowires. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Control of zinc oxide nanowire array properties with electron-beam lithography templating for photovoltaic applications

    Science.gov (United States)

    Nicaise, Samuel M.; Cheng, Jayce J.; Kiani, Amirreza; Gradečak, Silvija; Berggren, Karl K.

    2015-02-01

    Hydrothermally synthesized zinc oxide nanowire arrays have been used as nanostructured acceptors in emerging photovoltaic (PV) devices. The nanoscale dimensions of such arrays allow for enhanced charge extraction from PV active layers, but the device performance critically depends on the nanowire array pitch and alignment. In this study, we templated hydrothermally-grown ZnO nanowire arrays via high-resolution electron-beam-lithography defined masks, achieving the dual requirements of high-resolution patterning at a pitch of several hundred nanometers, while maintaining hole sizes small enough to control nanowire array morphology. We investigated several process conditions, including the effect of annealing sputtered and spincoated ZnO seed layers on nanowire growth, to optimize array property metrics—branching from individual template holes and off-normal alignment. We found that decreasing template hole size decreased branching prevalence but also reduced alignment. Annealing seed layers typically improved alignment, and sputtered seed layers yielded nanowire arrays superior to spincoated seed layers. We show that these effects arose from variation in the size of the template holes relative to the ZnO grain size in the seed layer. The quantitative control of branching and alignment of the nanowire array that is achieved in this study will open new paths toward engineering more efficient electrodes to increase photocurrent in nanostructured PVs. This control is also applicable to inorganic nanowire growth in general, nanomechanical generators, nanowire transistors, and surface-energy engineering.

  14. Zinc oxide nanowire photodetectors with single-walled carbon nanotube thin-film electrodes.

    Science.gov (United States)

    Ates, Elif Selen; Kucukyildiz, Seyda; Unalan, Husnu Emrah

    2012-10-24

    In this study, transparent and flexible zinc oxide (ZnO) nanowire ultraviolet (UV) photodetectors prepared via a solution-based method in which single-walled carbon nanotube (SWNT) thin films were used as transparent electrodes are reported. The photoresponse current was found to be in proportion with the ZnO nanowire density, and the nanowire density could be tuned to increase the photocurrent by a factor of 300. The decay time for the fabricated photodetectors was found to be as low as 16 s. This study suggests the possibility of fabricating inexpensive, visible-blind UV photodetectors via solution-based methods.

  15. Development of gas sensors using ZnO nanostructures

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Different ZnO nanostructures such as nanowires, nanobelts and tetrapods have been grown and used for preparation of thick film (with random grain boundaries) as well as isolated nano- wire/nanobelt gas sensors. Sensitivity of different type of sensors has been studied to H2S and NO gases. The results show ...

  16. Growth of a Novel Nanostructured ZnO Urchin: Control of Cytotoxicity and Dissolution of the ZnO Urchin.

    Science.gov (United States)

    Imani, Roghayeh; Drašler, Barbara; Kononenko, Veno; Romih, Tea; Eleršič, Kristina; Jelenc, Janez; Junkar, Ita; Remškar, Maja; Drobne, Damjana; Kralj-Iglič, Veronika; Iglič, Aleš

    2015-12-01

    The applications of zinc oxide (ZnO) nanowires (NWs) in implantable wireless devices, such as diagnostic nanobiosensors and nanobiogenerators, have recently attracted enormous attention due to their unique properties. However, for these implantable nanodevices, the biocompatibility and the ability to control the behaviour of cells in contact with ZnO NWs are demanded for the success of these implantable devices, but to date, only a few contrasting results from their biocompatibility can be found. There is a need for more research about the biocompatibility of ZnO nanostructures and the adhesion and viability of cells on the surface of ZnO nanostructures. Here, we introduce synthesis of a new nature-inspired nanostructured ZnO urchin, with the dimensions of the ZnO urchin's acicula being controllable. To examine the biocompatibility and behaviour of cells in contact with the ZnO urchin, the Madin-Darby canine kidney (MDCK) epithelial cell line was chosen as an in vitro experimental model. The results of the viability assay indicated that, compared to control, the number of viable cells attached to the surface of the ZnO urchin and its surrounding area were reduced. The measurements of the Zn contents of cell media confirmed ZnO dissolution, which suggests that the ZnO dissolution in cell culture medium could lead to cytotoxicity. A purposeful reduction of ZnO cytotoxicity was achieved by surface coating of the ZnO urchin with poly(vinylidene fluorid-co-hexafluoropropylene) (PVDF-HFP), which changed the material matrix to slow the Zn ion release and consequently reduce the cytotoxicity of the ZnO urchin without reducing its functionality.

  17. Influence of the Hydrothermal Method Growth Parameters on the Zinc Oxide Nanowires Deposited on Several Substrates

    Directory of Open Access Journals (Sweden)

    Concepción Mejía-García

    2014-01-01

    Full Text Available We report the synthesis of ZnO nanowires grown on several substrates (PET, glass, and Si using a two-step process: (a preparation of the seed layer on the substrate by spin coating, from solutions of zinc acetate dihydrate and 1-propanol, and (b growth of the ZnO nanostructures by dipping the substrate in an equimolar solution of zinc nitrate hexahydrate and hexamethylenetetramine. Subsequently, films were thermally treated with a commercial microwave oven (350 and 700 W for 5, 20, and 35 min. The ZnO nanowires obtained were characterized structurally, morphologically, and optically using XRD, SEM, and UV-VIS transmission, respectively. XRD patterns spectra revealed the presence of Zn(OH2 on the films grown on glass and Si substrates. A preferential orientation along c-axis directions for films grown on PET substrate was observed. An analysis by SEM revealed that the growth of the ZnO nanowires on PET and glass is better than the growth on Si when the same growth parameters are used. On glass substrates, ZnO nanowires less than 50 nm in diameter and between 200 nm and 1200 nm in length were obtained. The ZnO nanowires band gap energy for the films grown on PET and glass was obtained from optical transmission spectra.

  18. Dimensional effects in semiconductor nanowires; Dimensionseffekte in Halbleiternanodraehten

    Energy Technology Data Exchange (ETDEWEB)

    Stichtenoth, Daniel

    2008-06-23

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

  19. Superhydrophobicity of Hierarchical and ZNO Nanowire Coatings

    Science.gov (United States)

    2014-01-01

    nanoelectronics, nanoparticles , quantum dots 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 9 19a. NAME OF... paints for boats,3 optics,4 and optoelectronics.5 Superhydrophobicity cau- ses a high water contact angle (160.4) and low contact angle hysteresis (ɝ

  20. Synthesis and characterization of p-n homojunction-containing zinc oxide nanowires.

    Science.gov (United States)

    Li, Guohua; Sundararajan, Abhishek; Mouti, Anas; Chang, Yao-Jen; Lupini, Andrew R; Pennycook, Stephen J; Strachan, Douglas R; Guiton, Beth S

    2013-03-21

    We illustrate a simple method to synthesize highly ordered ZnO axial p-n homojunction-containing nanowires using a low temperature method, and on a variety of substrates. X-ray diffraction, scanning transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy are used to reveal high quality single-crystalline wires with a [001] growth direction. The study of electrical transport through a single nanowire based device and cathodoluminescence via scanning transmission electron microscopy demonstrates that an axial p-n junction exists within each ZnO nanowire. This represents the first low temperature synthesis of axial p-n homojunction-containing ZnO nanowires with uniform and controllable diameters.

  1. Materials and Devices Research of PPV-ZnO Nanowires for Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Zhang Xiao-Zhou

    2012-01-01

    Full Text Available Bulk heterojunction photovoltaic devices, which use the conjugated polymer poly(2-methoxyl-5-(2′-ethylhexyloxy-1,4-phenylenevinylene (MEH-PPV as the electron donor and crystalline ZnO nanowires as the electron acceptor, have been studied in this work. The ZnO nanowires were prepared through a chemical vapor deposition mechanism. The dissolved MEH-PPV polymer was spin-coated onto the nanowires. The scanning electron microscope images showed that the ZnO nanowires were covered with a single layer of the polymer, and these materials were used to design a heterojunction solar cell. This solar cell displayed improved performance compared with the devices that were made from only the MEH-PPV polymer. This observed improvement is correlated with the improved electron transport that is perpendicular to the plane of the film. A solar power conversion efficiency of 1.37% was achieved under an AM1.5 illumination.

  2. Light Output Improvement of GaN-Based Light-Emitting Diodes Using Hydrothermally Grown ZnO Nanotapers

    Science.gov (United States)

    Tu, Yung-Chun; Wang, Shui-Jinn; Lin, Jia-Ching; Tsai, Fu-Shou; Lin, Tseng-Hsing; Uang, Kai-Ming; Chen, Tron-Min

    2013-06-01

    A new two-step hydrothermal growth (HTG) process with a shorter processing time and better growth control is proposed for the synthesis of ZnO nanotapers (NTs). The application of HTG ZnO NTs as surface roughening nanostructures to improve the light output power (Lop) of GaN-based LEDs is demonstrated. Compared with that of ZnO nanowires, the use of ZnO NTs leads to an improvement in Lop by 24.5% at 350 mA, which could be attributed to the fact that tapered ends of ZnO NTs offer more constructive photon scattering to maximize light extraction.

  3. Synthesis of Vertically-Aligned Zinc Oxide Nanowires and Their Application as a Photocatalyst

    Directory of Open Access Journals (Sweden)

    Qiong Zhou

    2017-01-01

    Full Text Available Vertically aligned zinc oxide (ZnO nanowires were hydrothermally synthesized on a glass substrate with the assistance of a pre-coated ZnO seeding layer. The crystalline structure, morphology and transmission spectrum of the as-synthesized sample were characterized by X-ray diffraction (XRD, field-emission scanning electron microscopy (FE-SEM, and ultraviolet-visible (UV-Vis spectrophotometry, respectively, indicating a wurzite ZnO material of approximately 100 nm wire diameter and absorbance at 425 nm and lower wavelengths. The photocatalytic activity of the sample was tested via the degradation of methyl orange in aqueous solution under UV-A irradiation. The synthesized nanowires showed a high photocatalytic activity, which increased up to 90% degradation in 2 h as pH was increased to 12. It was shown that the photocatalytic activity of the nanowires was proportional to the length to diameter ratio of the nanowires, which was in turn controlled by the growth time and grain size of the seed layer. Estimates suggest that diffusion into the regions between nanowires may be significantly hindered. Finally, the reusability of the prepared ZnO nanowire samples was also investigated, with results showing that the nanowires still showed 97% of its original photoactivity after ten cycles of use.

  4. Synthesis of Vertically-Aligned Zinc Oxide Nanowires and Their Application as a Photocatalyst

    Science.gov (United States)

    Zhou, Qiong; Wen, John Z.; Zhao, Pei; Anderson, William A.

    2017-01-01

    Vertically aligned zinc oxide (ZnO) nanowires were hydrothermally synthesized on a glass substrate with the assistance of a pre-coated ZnO seeding layer. The crystalline structure, morphology and transmission spectrum of the as-synthesized sample were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and ultraviolet-visible (UV-Vis) spectrophotometry, respectively, indicating a wurzite ZnO material of approximately 100 nm wire diameter and absorbance at 425 nm and lower wavelengths. The photocatalytic activity of the sample was tested via the degradation of methyl orange in aqueous solution under UV-A irradiation. The synthesized nanowires showed a high photocatalytic activity, which increased up to 90% degradation in 2 h as pH was increased to 12. It was shown that the photocatalytic activity of the nanowires was proportional to the length to diameter ratio of the nanowires, which was in turn controlled by the growth time and grain size of the seed layer. Estimates suggest that diffusion into the regions between nanowires may be significantly hindered. Finally, the reusability of the prepared ZnO nanowire samples was also investigated, with results showing that the nanowires still showed 97% of its original photoactivity after ten cycles of use. PMID:28336843

  5. Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

    Science.gov (United States)

    Sodano, Henry A.; Brett, Robert

    2011-01-01

    The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

  6. ZnO-nanowire as a nanogenerator?

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Markus Andreas; Senz, Stephan; Alexe, Marin; Goesele, Ulrich [Max Planck Institut fuer Mikrostrukturphysik, Halle (Germany)

    2008-07-01

    Recently nanogenerators for powering nanodevices were reported in which ZnO-nanowire arrays convert mechanical energy in electrical energy by bending the ZnO-nanowires. We simulate the experiments in which the ZnO nanowires were bent by AFM tip by FEM-calculations for an ideal nonconducting piezoelectric ZnO-nanowire with a length of 600 nm and a diameter of 50 nm fixed perpendicular to a substrate. The top part of this nanowire was bent about 140 nm by a force applied at the top of the nanowire. At the point of the applied force the electrical potential has a maximum of +1.3 V. In the rest of the nanowire the electrical potential is +0.3 V for the stretched side and -0.3 V for the compressed. The piezoelectric charge generate the signal on the capacitance between the two sides, which is about 10{sup -5} pF for the whole wire. A lower value of 10{sup -7} pF is estimated for the AFM point contact. However, most ZnO-nanowires are n-doped semiconductors with a typically resistivity of 1 {omega}cm. One consequence is a very fast discharging of the piezoelectric generate charge in the order of magnitude of 1 ps. Even, in the case of an ideal nonconducting nanowire, the voltage at the input capacity of any preamplifier ({proportional_to}1-5 pF) would be of the order of 10{sup -7} V, which corresponds to a charge of about one electron.

  7. Electrodeposition of textured Bi{sub 27}Sb{sub 28}Te{sub 45} nanowires with enhanced electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Maksudul, E-mail: maksudul.hasan@tyndall.ie [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Gautam, Devendraprakash [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Enright, Ryan [Thermal Management Research Group, Efficient Energy Transfer Department, Bell Labs Ireland, Alcatel-Lucent Ireland Ltd., Dublin (Ireland)

    2016-04-15

    This work presents the template based pulsed potential electrodeposition technique of highly textured single crystalline bismuth antimony telluride (Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} nanowires from a single aqueous electrolyte. Cyclic voltammetry was used as an electroanalytical tool to assess the effect of the precursor concentrations on the composition of the deposits and to determine the deposition potential for each element. Pulsed potential electrodeposition was then applied on a gold-coated anodised alumina template to examine the effect of the pulse parameters on the composition and texture of Bi{sub 27}Sb{sub 28}Te{sub 45} nanowires. The nanowires are cylindrical in shape formed during the deposition inside the porous template and highly textured as they are decorated with sparse distribution of small crystal domains. The electrical conductivity (24.1 × 10{sup 4} S m{sup −1}) of a single nanowire was measured using a four-point probe technique implemented on a custom fabricated test chip. In this work, we demonstrated that crystal orientation with respect to the transport direction controlled by tuning the pulsed electrodeposition parameters. This allowed us to realise electrical conductivities ∼2.5 times larger than Sb doped bismuth-tellurium based ternary material systems and similar to what is typically seen in binary systems. - Highlights: • Pulsed electrodeposition is described towards fabrication of (Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} nanowires. • The adopted method is compatible with existing CMOS process. • The nanowires were fabricated as highly textured to enhance phonon scattering. • The electrical conductivity is ∼2.5 times larger than the current ternary materials.

  8. Gallium nitride nanowire based nanogenerators and light-emitting diodes.

    Science.gov (United States)

    Chen, Chih-Yen; Zhu, Guang; Hu, Youfan; Yu, Jeng-Wei; Song, Jinghui; Cheng, Kai-Yuan; Peng, Lung-Han; Chou, Li-Jen; Wang, Zhong Lin

    2012-06-26

    Single-crystal n-type GaN nanowires have been grown epitaxially on a Mg-doped p-type GaN substrate. Piezoelectric nanognerators based on GaN nanowires are investigated by conductive AFM, and the results showed an output power density of nearly 12.5 mW/m(2). Luminous LED modules based on n-GaN nanowires/p-GaN substrate have been fabricated. CCD images of the lighted LED and the corresponding electroluminescence spectra are recorded at a forward bias. Moreover, the GaN nanowire LED can be lighted up by the power provided by a ZnO nanowire based nanogenerator, demonstrating a self-powered LED using wurtzite-structured nanomaterials.

  9. Nanowire Lasers

    Directory of Open Access Journals (Sweden)

    Couteau C.

    2015-05-01

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

  10. First-principles calculations of atomic and electronic properties of ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H.; Fan, W.; Fang, D. [Nano-organic Photoelectronic Laboratory, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Rosa, A.L.; Frauenheim, T. [BCCMS, University of Bremen (Germany); Zhang, R.Q. [Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China)

    2010-10-15

    We employ density-functional theory within the generalized-gradient approximation to investigate the formation energies and atomic and electronic structure of ZnO nanowires and nanotubes (NTs). We find that relaxations on the facets of the bare wires are very similar to those in nonpolar (10 anti 10) surfaces and play an important role in stabilizing the nanowires. All bare wires are found to be semiconducting, with band gaps larger than that in bulk ZnO. We further investigated hydrogen and water adsorption on ZnO nanowires. We find that the electronic structure of ZnO nanowires can be tuned by hydrogen adsorption and that adsorption of water leads to dissociation of a half-monolayer. Next, the stability of ZnO NTs has been investigated. We show that multiwall NTs are more stable than single-walled tubes. Finally, point defects in ZnO NTs have been investigated using spin-polarized calculations. All calculations were shown to introduce defect levels in the band gap, thus changing the electronic structure of the NTs drastically. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  11. Effects of piezoelectric potential on the transport characteristics of metal-ZnO nanowire-metal field effect transistor

    KAUST Repository

    Gao, Zhiyuan

    2009-01-01

    We have investigated the effects of piezoelectric potential in a ZnO nanowire on the transport characteristics of the nanowire based field effect transistor through numerical calculations and experimental observations. Under different straining conditions including stretching, compressing, twisting, and their combination, a piezoelectric potential is created throughout the nanowire to modulatealternate the transport property of the metal-ZnO nanowire contacts, resulting in a switch between symmetric and asymmetric contacts at the two ends, or even turning an Ohmic contact type into a diode. The commonly observed natural rectifying behavior of the as-fabricated ZnO nanowire can be attributed to the strain that was unpurposely created in the nanowire during device fabrication and material handling. This work provides further evidence on piezopotential governed electronic transport and devices, e.g., piezotronics.

  12. Magnetism in dopant-free ZnO nanoplates.

    Science.gov (United States)

    Hong, Jung-Il; Choi, Jiil; Jang, Seung Soon; Gu, Jiyeong; Chang, Yangling; Wortman, Gregory; Snyder, Robert L; Wang, Zhong Lin

    2012-02-08

    It is known that bulk ZnO is a nonmagnetic material. However, the electronic band structure of ZnO is severely distorted when the ZnO is in the shape of a very thin plate with its dimension along the c-axis reduced to a few nanometers while keeping the bulk scale sizes in the other two dimensions. We found that the chemically synthesized ZnO nanoplates exhibit magnetism even at room temperature. First-principles calculations show a growing asymmetry in the spin distribution within the distorted bands formed from Zn (3d) and O (2p) orbitals with the reduction of thickness of the ZnO nanoplates, which is suggested to be responsible for the observed magnetism. In contrast, reducing the dimension along the a- or b-axes of a ZnO crystal does not yield any magnetism for ZnO nanowires that grow along c-axis, suggesting that the internal electric field produced by the large {0001} polar surfaces of the nanoplates may be responsible for the distorted electronic band structures of thin ZnO nanoplates. © 2012 American Chemical Society

  13. Effect of Cr{sub 2}O{sub 3} on the microstructure and non-ohmic properties of (Co, Sb)-doped SnO{sub 2} varistors

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar M, J. A. [Centro de Investigac ion en Materiales Avanzados, S. C., Alianza Norte No. 202, Parque de Investigacion e Innovacion Tecnologica, Nueva Carretera Aeropuerto Km. 10 Apodaca 66600, Nuevo Leon (Mexico); Pech C, M. I. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Carretera Saltillo-Monterrey Km. 13, Saltillo 25900, Coahuila (Mexico); Hernandez, M. B.; Rodriguez, E.; Garcia O, L. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon (Mexico); Glot, A. B., E-mail: josue.aguilar@cimav.edu.mx [Universidad Tecnologica de la Mixteca, Division de Estudios de Posgrado, Carretera Acatlima Km. 2.5, Huajuapan de Leon 69000, Oaxaca (Mexico)

    2013-10-01

    The effect of Cr{sub 2}O{sub 3} addition on the physical characteristics, microstructure, and current-voltage properties of (Co-Sb)-doped SnO{sub 2} varistors was investigated. SnO{sub 2}-Co{sub 3}O{sub 4}-Sb{sub 2}O{sub 5} ceramics with additions of 0.0, 0.03, 0.05 and 0.07 mol % Cr{sub 2}O{sub 3} were sintered at 1350 C under ambient atmosphere and characterized micro structurally and electrically. The characterization by X-ray diffraction and scanning electron microscopy show that the microstructure remains as a single phase material with multimodal size distribution of SnO{sub 2} grains. The greatest effect of Cr{sub 2}O{sub 3} additions is manifested in the electric breakdown field. Additions of high levels (0.07 and 0.05 %) of this oxide promote and increase of approximately 55% in this parameter compared to the Cr{sub 2}O{sub 3}-free sample. Another physical property is affected: the measured density values decreases as the Cr{sub 2}O{sub 3} content increases. A change in the nonlinearity coefficient value is produced only at the highest Cr{sub 2}O{sub 3} content while at intermediate levels there is not change at all. Consequently, when seeking high nonlinearity coefficients, intermediate levels of Cr{sub 2}O{sub 3} are not recommended. (Author)

  14. Formation of star nanowires of sulfur-doped zinc oxide: Ab initio calculations

    Directory of Open Access Journals (Sweden)

    Qiu-Bao Lin

    2016-09-01

    Full Text Available ZnO nanowires are hexagonally shaped under normal growth conditions, but are transformed from a hexagon to hexagram ones when sulfur dopants are added into the growth solution. The formation mechanism of the hexagram-shaped ZnO nanowires is further studied by the ab initio calculations in this paper. The present calculations support the fact that the hexagonally shaped ZnO nanowires are transformed to hexagram shaped ones when the O atoms on the side surfaces of the nanowires are replaced by S atoms in certain quantities. It indicates that the ratio of sulfur content plays an important role in the hexagram formation. The results of the electronic charge densities indicate that the charge transfer makes the S-Zn bond longer than that of O-Zn. The new charge distribution on the side planes due to the S atoms replacement leads to the formation of the hexagram-shaped nanowires. The calculation on the electronic properties shows that a sulfur-doped hexagram ZnO nanowire is an indirect band gap semiconductor with a narrow gap. When dopant is increased, the gap will decrease.

  15. ZnO Nanostructure-Based Intracellular Sensor

    Directory of Open Access Journals (Sweden)

    Muhammad H. Asif

    2015-05-01

    Full Text Available Recently ZnO has attracted much interest because of its usefulness for intracellular measurements of biochemical species by using its semiconducting, electrochemical, catalytic properties and for being biosafe and biocompatible. ZnO thus has a wide range of applications in optoelectronics, intracellular nanosensors, transducers, energy conversion and medical sciences. This review relates specifically to intracellular electrochemical (glucose and free metal ion biosensors based on functionalized zinc oxide nanowires/nanorods. For intracellular measurements, the ZnO nanowires/nanorods were grown on the tip of a borosilicate glass capillary (0.7 µm in diameter and functionalized with membranes or enzymes to produce intracellular selective metal ion or glucose sensors. Successful intracellular measurements were carried out using ZnO nanowires/nanorods grown on small tips for glucose and free metal ions using two types of cells, human fat cells and frog oocytes. The sensors in this study were used to detect real-time changes of metal ions and glucose across human fat cells and frog cells using changes in the electrochemical potential at the interface of the intracellular micro-environment. Such devices are helpful in explaining various intracellular processes involving ions and glucose.

  16. On the origin of green emission in zinc sulfide nanowires prepared by a thermal evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Trung, D.Q.; Tuan, N.T.; Chung, H.V. [Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hanoi 10000 (Viet Nam); Duong, P.H. [Institute of Materials Science (IMS), VAST, Hanoi (Viet Nam); Huy, P.T., E-mail: huy.phamthanh@hust.edu.vn [Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hanoi 10000 (Viet Nam)

    2014-09-15

    The optical properties and morphological features of ZnS nanowires fabricated by a thermal evaporation process have been systematically studied. We have observed both ZnS nanowires and ZnO structures in one fabrication batch. One common green emission peak in the photoluminescence spectra centered at 516–520 nm appears and is independent of the don pants of the source materials and the catalytic metals. This peak is attributed to the contribution of ZnO structures by means of X-ray diffraction and Raman spectroscopic analysis. The exponential degradation of the photoluminescence intensity of ZnS and ZnO in air under UV laser irradiation not only indicates the significant role of oxygen diffusing into ZnO structures but also provides additional confirmation regarding the degradation that occurs inside ZnS nanowires. The emission model related to defects and ligand fields that occurs in both ZnS and ZnO as a result of this fabrication approach is discussed. - Highlights: • Degradation of the PL intensity occurring in ZnS:Ag nanowires in air under UV laser irradiation. • The inset displays the direct observation at room temperature of the degradation of both components: ZnS at 448 nm and ZnO at 517 nm. • The exponential decrease implies that oxygen is diffusing into the structure.

  17. Fabrication and characterization of Ga-doped ZnO / Si heterojunction nanodiodes

    Science.gov (United States)

    Akgul, Guvenc; Akgul, Funda Aksoy

    2017-02-01

    In this study, temperature-dependent electrical properties of n-type Ga-doped ZnO thin film / p-type Si nanowire heterojunction diodes were reported. Metal-assisted chemical etching (MACE) process was performed to fabricate Si nanowires. Ga-doped ZnO films were then deposited onto nanowires through chemical bath deposition (CBD) technique to build three-dimensional nanowire-based heterojunction diodes. Fabricated devices revealed significant diode characteristics in the temperature range of 220 - 360 K. Electrical measurements shown that diodes had a well-defined rectifying behavior with a good rectification ratio of 103 ±3 V at room temperature. Ideality factor (n) were changed from 2.2 to 1.2 with increasing temperature.

  18. EDTA-assisted synthesis of rose-like ZnO architectures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhen [Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 201800 (China); Shanghai Applied Radiation Institute, Shanghai University, Shanghai 201800 (China); Fang, Yaoguo [Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 201800 (China); Peng, Liwei; Wu, Minghong [Shanghai Applied Radiation Institute, Shanghai University, Shanghai 201800 (China); Pan, Dengyu

    2010-10-15

    Rose-like ZnO nanostructures were prepared by a low-temperature solution route with assistance of ethylenediaminetetraacetic acid disodium (EDTA-2Na). The morphology of ZnO nanostructures was found to change from nanowire arrays to rose- and tower-like architectures with increasing the molar ratio of EDTA-2Na/Zn{sup 2+}. Also, the shape evolution of ZnO nanostructures with time was observed from flat nanosheets to wrinkled nanosheets and to rose-like nanostructures. EDTA-2Na as a strong complexing agent was found to play a key role in the shape evolution. Photoluminescence spectra show that the rose-like ZnO architectures have more defects than the nanowire arrays. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Structure and lattice dynamics of group-V-elements in ZnO; Struktur und Gitterdynamik von Gruppe-V-Elementen in ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Felice

    2010-02-15

    spectra of Sb-doped ZnO thin-films show a dominant broad mode in the region of the ZnO longitudinal optical (LO) phonons. A similar behavior is observed for spectra of ZnO thin-films doped with nitrogen (N). It is shown that this broad mode is caused by an impurity-induced resonant enhancement of LO-phonons due to Froehlich interaction. In general, N-doped samples grown by metal organic vapour phase epitaxy were found to be systematically and intensely contaminated with carbon (C). The latter not only generates defect levels in the ZnO band gap, but forms C{identical_to}N-complexes and thus reduces the concentration of N acceptors. Furthermore, it is shown that intrinsic defects add to the compensation of N acceptors. For that purpose, density-functional-theory calculations were combined with a Raman analysis of Zn-isotope induced frequency shifts. Thus, it was possible to identify the controversially discussed microscopic structure of defect complexes causing the local modes at 275 and 510 cm{sup -1}. These Zni-NO and Zni-Oi-NO-complexes consist of interstitial Zn and O atoms attached to N acceptor atoms. Additionally, the incorporation of molecular nitrogen is shown by the mode observed at 2306 cm{sup -1}. In summary, the problem of Al donor diffusion from sapphire substrates is circumvented by a substitution with MgO substrates. Different mechanisms are identified that hinder p-type doping with Sb and N. As for Sb, it is difficult to achieve a homogeneous distribution. N tends to form complexes with other impurities and intrinsic defects, which limit the doping efficiency.

  20. Fabrication of lateral electrodes on semiconductor nanowires through structurally matched insulation for functional optoelectronics.

    Science.gov (United States)

    Sheng, Yun; Sun, Huabin; Wang, Jianyu; Gao, Fan; Wang, Junzhuan; Pan, Lijia; Pu, Lin; Zheng, Youdou; Shi, Yi

    2013-01-18

    A strategy of using structurally matched alumina insulation to produce lateral electrodes on semiconductor nanowires is presented. Nanowires in the architecture are structurally matched with alumina insulation using selective anodic oxidation. Lateral electrodes are fabricated by directly evaporating metallic atoms onto the opposite sides of the nanowires. The integrated architecture with lateral electrodes propels carriers to transport them across nanowires and is crucially beneficial to the injection/extraction in optoelectronics. The matched architecture and the insulating properties of the alumina layer are investigated experimentally. ZnO nanowires are functionalized into an ultraviolet photodiode as an example. The present strategy successfully implements an advantageous architecture and is significant in developing diverse semiconductor nanowires in optoelectronic applications.

  1. Tailoring the properties of semiconductor nanowires using ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Ronning, C.; Borschel, C.; Geburt, S.; Niepelt, R. [Institute of Solid State Physics, Friedrich-Schiller-University of Jena (Germany); Mueller, S.; Stichtenoth, D. [II. Institute of Physics, University of Goettingen (Germany); Richters, J.P.; Dev, A.; Voss, T. [Institute of Solid State Physics, University of Bremen (Germany); Chen, L.; Heimbrodt, W. [Department of Physics and Material Sciences, Philipps-University of Marburg (Germany); Gutsche, C.; Prost, W. [Institute for Semiconductor Technology, University of Duisburg-Essen, Duisburg (Germany)

    2010-10-15

    This review demonstrates that ion irradiation is a very useful tool in order to tailor the properties of semiconductor nanowires. Besides optical and electrical doping provided by adequate ion species and ion energies, one can use ion beams also for the controlled shaping of the morphology of nanostructures. Here, one utilizes the commonly as 'negative' described characteristics of ion implantation: defect formation and sputtering. We show that ion beams can be even used for an alignment of the nanowires. Furthermore, we report here on several successful experiments in order to modify the electrical and optical properties in a controlled manner of ZnO semiconductor nanowires by the use of transition metals, rare earth elements and hydrogen ions. Schematic illustration of ion beam doping of a single contacted nanowire. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. A generic approach for vertical integration of nanowires.

    Science.gov (United States)

    Latu-Romain, E; Gilet, P; Noel, P; Garcia, J; Ferret, P; Rosina, M; Feuillet, G; Lévy, F; Chelnokov, A

    2008-08-27

    We report on the collective integration technology of vertically aligned nanowires (NWs). Si and ZnO NWs have been used in order to develop a generic technological process. Both mineral and organic planarizations of the as-grown nanowires have been achieved. Chemical vapour deposition (CVD) oxides, spin on glass (SOG), and polymer have been investigated as filling materials. Polishing and/or etching of the composite structures have been set up so as to obtain a suitable morphology for the top and bottom electrical contacts. Electrical and optical characterizations of the integrated NWs have been performed. Contacts ohmicity has been demonstrated and specific contact resistances have been reported. The photoconducting properties of polymer-integrated ZnO NWs have also been investigated in the UV-visible range through collective electrical contacts. A small increase of the resistivity in the ZnO NWs under sub-bandgap illumination has been observed and discussed. A comparison of the photoluminescence (PL) spectra at 300 K of the as-grown and SOG-integrated ZnO nanowires has shown no significant impact of the integration process on the crystal quality of the NWs.

  3. Preferential growth of ZnO thin films by the atomic layer deposition technique

    Science.gov (United States)

    Pung, Swee-Yong; Choy, Kwang-Leong; Hou, Xianghui; Shan, Chongxin

    2008-10-01

    Preferred orientation of ZnO thin films deposited by the atomic layer deposition (ALD) technique could be manipulated by deposition temperature. In this work, diethyl zinc (DEZn) and deionized water (H2O) were used as a zinc source and oxygen source, respectively. The results demonstrated that (10.0) dominant ZnO thin films were grown in the temperature range of 155-220 °C. The c-axis crystal growth of these films was greatly suppressed. Adhesion of anions (such as fragments of an ethyl group) on the (00.2) polar surface of the ZnO thin film was believed to be responsible for this suppression. In contrast, (00.2) dominant ZnO thin films were obtained between 220 and 300 °C. The preferred orientations of (10.0) and (00.2) of the ZnO thin films were examined by XRD texture analysis. The texture analysis results agreed well with the alignments of ZnO nanowires (NWs) which were grown from these ZnO thin films. In this case, the nanosized crystals of ZnO thin films acted as seeds for the growth of ZnO nanowires (NWs) by chemical vapor deposition (CVD) process. The highly (00.2) textured ZnO thin films deposited at high temperatures, such as 280 °C, contained polycrystals with the c axis perpendicular to the substrate surface and provided a good template for the growth of vertically aligned ZnO NWs.

  4. Development of a zinc oxide nanowire interphase for enhanced structural composites

    Science.gov (United States)

    Ehlert, Gregory John

    Continuous fiber reinforced polymers (CFRPs) form the backbone of the high strength, low density material systems that will be central to the next generation of transportation vehicles. CFRPs, with a compliant matrix between relatively stiff fibers, localize stress at the interface between the two different phases to cause the interface to dominate many bulk material properties. As such, the two phase composite design problem generally has three selections; fiber, matrix and the interface between the two. This work has developed a unique ZnO nanowire interphase to improve the properties of the interface. Whiskerization, the deposition of an array of whiskers on the surface of a fiber, enables enhancement of the interfacial properties by causing fibers to interlock thus allowing the formation of a graded interface to reduce the stress concentration between the two phases. Whiskerization techniques have existed for some time; however ZnO nanowires offer a radical departure from existing technologies because ZnO nanowires can be deposited at low temperatures (90 °C) aqueous solutions. The high performance afforded by ZnO nanowires is documented for the first time in this work. This work will demonstrate the ability of a ZnO nanowire interphase to reinforce the interface of both aramid and carbon fiber composites. The interfacial shear strength of single fiber aramid composites is enhanced by 41% and single carbon fiber composite are improved by 110% with this process. Lamina scale testing on unidirectional carbon fiber composites demonstrates a 37% increase in shear strength and a 38% increase in shear modulus for the affected fibers. Given that ZnO nanowires are grown directly onto the underlying fiber, the interface between the nanowires and fiber will have low surface area and minimal interlocking, which implies that the chemical adhesion of the nanowires is strong. This work develops new functionalization procedures that directly control the interface chemistry

  5. Covalent functionalization of zinc oxide nanowires for high sensitivity p-nitrophenol detection in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Anurag, E-mail: agupta16@crimson.ua.edu [The University of Alabama, 101 Houser Hall, Tuscaloosa, AL 35487 (United States); Kim, Bruce C. [The University of Alabama, 101 Houser Hall, Tuscaloosa, AL 35487 (United States); Edwards, Eugene; Brantley, Christina; Ruffin, Paul [U.S. Army, RDECOM/AMRDEC, 5400 Fowler Road, Redstone Arsenal, AL 35898 (United States)

    2012-11-01

    Highlights: Black-Right-Pointing-Pointer High quality synthesis of ZnO nanowires through a CVD process and characterization. Black-Right-Pointing-Pointer Covalent functionalization with fluorescent receptor to produce novel hybrid organic-inorganic system. Black-Right-Pointing-Pointer Surface sensitive XPS results are analyzed to deduce proof of covalent functionalization. Black-Right-Pointing-Pointer Detection limit of 28 ppb estimated for sensor through fluorescence studies. Black-Right-Pointing-Pointer Highly sensitive and selective sensing platform design is proposed based on empirical findings. - Abstract: High-quality zinc oxide (ZnO) nanowires were synthesized using the atmospheric chemical vapor deposition technique and were appropriately characterized. Subsequently, the nanowire surface was covalently grafted with 1-pyrenebutyric acid (PBA) fluorophore, and surface-sensitive X-ray photoelectron spectroscopy and Fourier transform infrared-attenuated total reflectance spectroscopy were utilized to confirm the functionalization of 1-pyrenebutyric acid on the nanowire surface. Additionally, photoluminescence (PL) measurements were used to evaluate the optical behavior of pristine nanowires. Through fluorescence quenching of 1-pyrenebutyric acid by p-nitrophenol, a detection limit of 28 ppb was estimated. Based on these findings, ZnO nanowires functionalized with 1-pyrenebutyric acid are envisaged as extremely sensitive platforms for the ultra-trace detection of p-nitrophenol in biological systems.

  6. Wide Bandgap Semiconductor Nanowires for Electronic, Photonic and Sensing Devices

    Science.gov (United States)

    2012-01-05

    vapor deposition ( CVD ) using gold thin films as catalyst on a Si wafer with an insulating SiO2 layer. The structural characterization of the as-grown...advantages in improved carrier confinement over their thin film counterparts. The bandgap of the ZnO may be increased by addition of Mg. Results: We...variety of wide bandgap nanowires using GaN and ZnO and made functional devices from them for sensing,electronics and photonics.These included a very

  7. ZnO Nanostructures for Tissue Engineering Applications.

    Science.gov (United States)

    Laurenti, Marco; Cauda, Valentina

    2017-11-06

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

  8. ZnO Nanostructures for Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Marco Laurenti

    2017-11-01

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

  9. Plasmonic Properties of Vertically Aligned Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Nanowires (NWs/Ag sheath composites were produced to investigate plasmonic coupling between vertically aligned NWs for surface-enhanced Raman scattering (SERS applications. In this investigation, two types of vertical NW arrays were studied; those of ZnO NWs grown on nanosphere lithography patterned sapphire substrate via vapor-liquid-solid (VLS mechanism and Si NW arrays produced by wet chemical etching. Both types of vertical NW arrays were coated with a thin layer of silver by electroless silver plating for SERS enhancement studies. The experimental results show extremely strong SERS signals due to plasmonic coupling between the NWs, which was verified by COMSOL electric field simulations. We also compared the SERS enhancement intensity of aligned and random ZnO NWs, indicating that the aligned NWs show much stronger and repeatable SERS signal than those grown in nonaligned geometries.

  10. Nanowire Optoelectronics

    Directory of Open Access Journals (Sweden)

    Wang Zhihuan

    2015-12-01

    Full Text Available Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, light-emitting diodes (LEDs, lasers, sensors, and optical antennas. We review the optical properties of these nanowires in terms of absorption, guiding, and radiation of light, which may be termed light management. Analysis of the interaction of light with long cylindrical/hexagonal structures with subwavelength diameters identifies radial resonant modes, such as Leaky Mode Resonances, or Whispering Gallery modes. The two-dimensional treatment should incorporate axial variations in “volumetric modes,”which have so far been presented in terms of Fabry–Perot (FP, and helical resonance modes. We report on finite-difference timedomain (FDTD simulations with the aim of identifying the dependence of these modes on geometry (length, width, tapering, shape (cylindrical, hexagonal, core–shell versus core-only, and dielectric cores with semiconductor shells. This demonstrates how nanowires (NWs form excellent optical cavities without the need for top and bottommirrors. However, optically equivalent structures such as hexagonal and cylindrical wires can have very different optoelectronic properties meaning that light management alone does not sufficiently describe the observed enhancement in upward (absorption and downward transitions (emission of light inNWs; rather, the electronic transition rates should be considered. We discuss this “rate management” scheme showing its strong dimensional dependence, making a case for photonic integrated circuits (PICs that can take advantage of the confluence of the desirable optical and electronic properties of these nanostructures.

  11. Synthesis and properties of novel liquid-medicine-filter shaped ZnO nanostructures

    Science.gov (United States)

    Zhuang, Huizhao; Xu, Peng; Li, Junlin

    2013-06-01

    Liquid-medicine-filter shaped ZnO nanostructures have been synthesized on Al2O3-coated Si (1 1 1) substrates by chemical vapor deposition method (CVD) at 1050 °C. Every liquid-medicine-filter shaped ZnO nanostructure is made up of one nanorod and two nanowires at the ends. The liquid-medicine-filter shaped ZnO nanostructures are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectrometer (EDS) photoluminescence (PL). The results indicate that the liquid-medicine-filter shaped ZnO nanostructures are wurtzite hexagonal structure and the growth direction is [0 0 0 1]. The liquid-medicine-filter shaped ZnO nanostructures became the new member of ZnO nanostructures for the novel configuration. PL reveals ultraviolet (UV) emission at 384 nm and a broad emission peak at 540 nm. These novel liquid-medicine-filter shaped ZnO nanostructures will provide an improvement for electronic and optical devices. The pre-prepared Al2O3 film on the Si (1 1 1) substrate solves the troublesome lattice mismatch problem between the Si substrate and ZnO, and makes the growth of liquid-medicine-filter shaped ZnO nanostructures more effective. In addition, the effect of screw dislocation and polar surfaces in understanding crystal growth mechanisms in nanometer scale were also provided.

  12. Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

    Directory of Open Access Journals (Sweden)

    T. Rakshit

    2013-11-01

    Full Text Available Pure and Sn doped ZnO nanostructures have been grown on SiO2/Si substrates by vapor-solid technique without using any catalysts. It has been found that the morphology of the nanostructures depend strongly on the growth temperature and doping concentration. By proper tuning of the growth temperature, morphology of pure ZnO can be changed from tetrapods to multipods. On the other hand, by varying the doping concentration of Sn in ZnO, the morphology can be tuned from tetrapods to flower-like multipods to nanowires. X-ray diffraction pattern reveals that the nanostructures have a preferred (0002 growth orientation, and they are tensile strained with the increase of Sn doping in ZnO. Temperature-dependent photoluminescence characteristics of these nanostructures have been investigated in the range from 10 to 300 K. Pure ZnO tetrapods exhibited less defect state emissions than that of pure ZnO multipods. The defect emission is reduced with low concentration of Sn doping, but again increases at higher concentration of doping because of increased defects. Transport properties of pure and Sn doped ZnO tetrapods have been studied using complex-plane impedance spectroscopy. The contribution from the arms and junctions of a tetrapod could be distinguished. Sn doped ZnO samples showed lower conductivity but higher relaxation time than that of pure ZnO tetrapods.

  13. Vertically aligned ZnO-ZnGa2O4 core-shell nanowires: from synthesis to optical properties

    Science.gov (United States)

    Zhong, Miao; Li, Yanbo; Tokizono, Takero; Zheng, Maojun; Yamada, Ichiro; Delaunay, Jean-Jacques

    2012-03-01

    Dense and vertically aligned ZnO-ZnGa2O4 core-shell nanowires were synthesized in large scale on a-plane sapphire substrates by a simple two-step chemical vapor deposition method. The synthesized ZnO-ZnGa2O4 core-shell nanowires were connected through their base by a thick underlayer of the same material realizing electrical contact of the nanostructured array. X-ray diffraction and transmission electron microscopy analyses of the core-shell nanowires reveal that the ZnO cores and ZnGa2O4 shells of the core-shell nanowires are of single-crystal quality and have aligned crystallographic orientations. The ultraviolet-visible diffuse reflectance spectra of the core-shell nanowires showed two sharp edges corresponding to near-band-edge absorption contributed by the ZnO cores and the ZnGa2O4 shells. Moreover, the room-temperature photoluminescence spectra of the core-shell nanowires gave three UV emission peaks coming from the ZnGa2O4 shells and the ZnO cores. The dense and vertically aligned ZnO-ZnGa2O4 core-shell nanowires showing promising photoelectric properties offer an ideal structure for light harvesting applications such as a photoanode in a photoelectrochemical water splitting cell.

  14. Effects of ZnO seed layer annealing temperature on the properties of n-ZnO NWs/Al(2)O(3)/p-Si heterojunction.

    Science.gov (United States)

    Gu, Yu-Zhu; Lu, Hong-Liang; Zhang, Yuan; Wang, Peng-Fei; Ding, Shi-Jin; Zhang, David Wei

    2015-09-21

    Effects of ZnO seed layer annealing temperature on the characteristics of the n-ZnO nanowires/Al(2)O(3)/p-Si heterojunction are investigated. Well-aligned ZnO nanowires (NWs) are grown through a simple hydrothermal method. Both the insertion of Al(2)O(3) buffer layer and the annealing treatment of ZnO seed layer are advantageous for the growth of ZnO NWs. This leads to a relatively high rectification ratio of up to 7.8 × 10(3) at ± 4.0 V in ZnO NWs/Al(2)O(3)/p-Si heterojunction photodetectors. The photoelectrical property of n-ZnO/p-Si photodetectors with an enhanced UV/dark current ratio as high as 30 under a reverse bias of 4.0 V is obtained.

  15. Metal Oxide Nanowire Preparation and Their Integration into Chemical Sensing Devices at the SENSOR Lab in Brescia

    Science.gov (United States)

    Bertuna, Angela; Faglia, Guido; Ferroni, Matteo; Kaur, Navpreet; Munasinghe Arachchige, Hashitha M. M.; Sberveglieri, Giorgio; Comini, Elisabetta

    2017-01-01

    Metal oxide 1D nanowires are probably the most promising structures to develop cheap stable and selective chemical sensors. The purpose of this contribution is to review almost two-decades of research activity at the Sensor Lab Brescia on their preparation during by vapor solid (n-type In2O3, ZnO), vapor liquid solid (n-type SnO2 and p-type NiO) and thermal evaporation and oxidation (n-type ZnO, WO3 and p-type CuO) methods. For each material we’ve assessed the chemical sensing performance in relation to the preparation conditions and established a rank in the detection of environmental and industrial pollutants: SnO2 nanowires were effective in DMMP detection, ZnO nanowires in NO2, acetone and ethanol detection, WO3 for ammonia and CuO for ozone. PMID:28468310

  16. Metal Oxide Nanowire Preparation and Their Integration into Chemical Sensing Devices at the SENSOR Lab in Brescia

    Directory of Open Access Journals (Sweden)

    Angela Bertuna

    2017-05-01

    Full Text Available Metal oxide 1D nanowires are probably the most promising structures to develop cheap stable and selective chemical sensors. The purpose of this contribution is to review almost two-decades of research activity at the Sensor Lab Brescia on their preparation during by vapor solid (n-type In2O3, ZnO, vapor liquid solid (n-type SnO2 and p-type NiO and thermal evaporation and oxidation (n-type ZnO, WO3 and p-type CuO methods. For each material we’ve assessed the chemical sensing performance in relation to the preparation conditions and established a rank in the detection of environmental and industrial pollutants: SnO2 nanowires were effective in DMMP detection, ZnO nanowires in NO2, acetone and ethanol detection, WO3 for ammonia and CuO for ozone.

  17. Vertical nanowire architectures

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  18. Microstructure development in zinc oxide nanowires and iron oxohydroxide nanotubes by cathodic electrodeposition in nanopores

    NARCIS (Netherlands)

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

    2011-01-01

    The cathodic electrodeposition of crystalline ZnO nanowires and amorphous FeO(OH) nanotubes in polycarbonate track-etched membranes with pore diameters of 50–200 nm is reported. Nitrate was used as a sacrificial precursor for the electrochemical generation of hydroxyl ions that raised the pH of the

  19. Nanowire-based detector

    Science.gov (United States)

    Berggren, Karl K; Hu, Xiaolong; Masciarelli, Daniele

    2014-06-24

    Systems, articles, and methods are provided related to nanowire-based detectors, which can be used for light detection in, for example, single-photon detectors. In one aspect, a variety of detectors are provided, for example one including an electrically superconductive nanowire or nanowires constructed and arranged to interact with photons to produce a detectable signal. In another aspect, fabrication methods are provided, including techniques to precisely reproduce patterns in subsequently formed layers of material using a relatively small number of fabrication steps. By precisely reproducing patterns in multiple material layers, one can form electrically insulating materials and electrically conductive materials in shapes such that incoming photons are redirected toward a nearby electrically superconductive materials (e.g., electrically superconductive nanowire(s)). For example, one or more resonance structures (e.g., comprising an electrically insulating material), which can trap electromagnetic radiation within its boundaries, can be positioned proximate the nanowire(s). The resonance structure can include, at its boundaries, electrically conductive material positioned proximate the electrically superconductive nanowire such that light that would otherwise be transmitted through the sensor is redirected toward the nanowire(s) and detected. In addition, electrically conductive material can be positioned proximate the electrically superconductive nanowire (e.g. at the aperture of the resonant structure), such that light is directed by scattering from this structure into the nanowire.

  20. Label-free detection of zinc oxide nanowire using a graphene wrapping method.

    Science.gov (United States)

    You, Juneseok; Jang, Kuewhan; Lee, Sangmyung; Bang, Doyeon; Haam, Seungjoo; Choi, Chang-Hwan; Park, Jinsung; Na, Sungsoo

    2015-06-15

    Zinc oxide nanowires (ZnO NWs) have been attempted to various applications, such as piezoelectric devices, energy harvesting devices, self-powered nanosensors, and biomedical devices. However, recent reports have shown the toxic effect of ZnO NWs. In this report, we described the detection of ZnO NWs, for the first time using reduced graphene oxide (RGO) wrapping method. By wrapping RGO to ZnO NW (RGO-ZnO NW), we are able to aggregate ZnO NWs and increase the sensing performance. The detection measurement is based on the resonance frequency shift derived from mass variation of RGO-ZnO NW adsorption on the DNA immobilized resonator. The resonator is able to detect ZnO NWs with detection limit of 100 ng mL(-1) which is 2 order below the fatal toxic concentration of ZnO NWs in Human Monocyte Macrophages (HMMs). Furthermore, the resonator is able to detect ZnO NWs in real tap water, showing the potential as ZnO NWs screening platform in real environmental aqua system. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Fabrication and characterization of well-aligned zinc oxide nanowire arrays and their realizations in Schottky-device applications

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Kin Mun; Grote, Fabian; Sun, Hui; Lei, Yong [Institute of Materials Physics, Center for Nanotechnology, University of Muenster (Germany); Wen, Liaoyong; Fang, Yaoguo [Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 201800 (China)

    2011-07-01

    Highly ordered arrays of vertical zinc oxide (ZnO) nanowires (NWs) or nanopores were fabricated in our group by first thermal evaporating a thin film of gold on the ultrathin alumina membrane (UTAM). The UTAM was then utilized as a substrate for the growth of the ordered arrays using a chemical vapour deposition (CVD) process. Alternatively, a modified CVD process was also used to fabricate ultra-long ZnO NWs with the length of the nanowire exceeding 100 micrometres. Subsequently, densely packed arrays of ZnO NWs Schottky diodes were synthesized by transferring the long NWs on a substrate using a dry contact printing method and the electrical contacts were made on the NWs with a photolithographic process. The interesting electrical properties of the ZnO NWs, diodes or other metal oxide NWs such as the field emission, electron transport and piezoelectric properties were characterized by current-voltage or by other appropriate measurements.

  2. Evaluation of Effective Elastic, Piezoelectric, and Dielectric Properties of SU8/ZnO Nanocomposite for Vertically Integrated Nanogenerators Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Neelam Mishra

    2017-01-01

    Full Text Available A nanogenerator is a nanodevice which converts ambient mechanical energy into electrical energy. A piezoelectric nanocomposite, composed of vertical arrays of piezoelectric zinc oxide (ZnO nanowires, encapsulated in a compliant polymeric matrix, is one of most common configurations of a nanogenerator. Knowledge of the effective elastic, piezoelectric, and dielectric material properties of the piezoelectric nanocomposite is critical in the design of a nanogenerator. In this work, the effective material properties of a unidirectional, unimodal, continuous piezoelectric composite, consisting of SU8 photoresist as matrix and vertical array of ZnO nanowires as reinforcement, are systematically evaluated using finite element method (FEM. The FEM simulations were carried out on cubic representative volume elements (RVEs. Four different types of arrangements of ZnO nanowires and three sizes of RVEs have been considered. The volume fraction of ZnO nanowires is varied from 0 to a maximum of 0.7. Homogeneous displacement and electric potential are prescribed as boundary conditions. The material properties are evaluated as functions of reinforcement volume fraction. The values obtained through FEM simulations are compared with the results obtained via the Eshelby-Mori-Tanaka micromechanics. The results demonstrate the significant effects of ZnO arrangement, ZnO volume fraction, and size of RVE on the material properties.

  3. Zinc oxide nanowire gamma ray detector with high spatiotemporal resolution

    Science.gov (United States)

    Mayo, Daniel C.; Nolen, J. Ryan; Cook, Andrew; Mu, Richard R.; Haglund, Richard F.

    2016-03-01

    Conventional scintillation detectors are typically single crystals of heavy-metal oxides or halides doped with rare-earth ions that record the recombination of electron-hole pairs by photon emission in the visible to ultraviolet. However, the light yields are typically low enough to require photomultiplier detection with the attendant instrumental complications. Here we report initial studies of gamma ray detection by zinc oxide (ZnO) nanowires, grown by vapor-solid deposition. The nanowires grow along the c-axis in a wurtzite structure; they are typically 80 nm in diameter and have lengths of 1- 2 μm. The nanowires are single crystals of high quality, with a photoluminescence (PL) yield from band-edge exciton emission in the ultraviolet that is typically one hundred times larger than the PL yield from defect centers in the visible. Nanowire ensembles were irradiated by 662 keV gamma rays from a Cs-137 source for periods of up to ten hours; gamma rays in this energy range interact by Compton scattering, which in ZnO creates F+ centers that relax to form singly-charged positive oxygen vacancies. Following irradiation, we fit the PL spectra of the visible emission with a sum of Gaussians at the energies of the known defects. We find highly efficient PL from the irradiated area, with a figure of merit approaching 106 photons/s/MeV of deposited energy. Over a period of days, the singly charged O+ vacancies relax to the more stable doubly charged O++ vacancies. However, the overall defect PL returns to pre-irradiation values after about a week, as the vacancies diffuse to the surface of these very thin nanowires, indicating that a self-healing process restores the nanowires to their original state.

  4. Luminescence and electrical properties of single ZnO/MgO core/shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Grinblat, Gustavo; Comedi, David [Laboratorio de Física del Sólido, Dep. de Física, FACET, Universidad Nacional de Tucumán, Tucumán, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Bern, Francis; Barzola-Quiquia, José; Esquinazi, Pablo, E-mail: esquin@physik.uni-leipzig.de [Division of Superconductivity and Magnetism, Institute for Experimental Physics II, University of Leipzig, D-04103 Leipzig (Germany); Tirado, Mónica [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Dep. de Física, FACET, Universidad Nacional de Tucumán, Tucumán (Argentina)

    2014-03-10

    To neutralise the influence of the surface of ZnO nanowires for photonics and optoelectronic applications, we have covered them with insulating MgO film and individually contacted them for electrical characterisation. We show that such a metal-insulator-semiconductor-type nanodevice exhibits a high diode ideality factor of 3.4 below 1 V. MgO shell passivates ZnO surface states and provides confining barriers to electrons and holes within the ZnO core, favouring excitonic ultraviolet radiative recombination, while suppressing defect-related luminescence in the visible and improving electrical conductivity. The results indicate the potential use of ZnO/MgO nanowires as a convenient building block for nano-optoelectronic devices.

  5. Stability of Organic Nanowires

    DEFF Research Database (Denmark)

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

    2011-01-01

    The morphological stability of organic nanowires over time and under thermal load is of major importance for their use in any device. In this study the growth and stability of organic nanowires from a naphthyl end-capped thiophene grown by organic molecular beam deposition is investigated via...... atomic force microscopy (AFM). Aging experiments under ambient conditions already show substantial morphological changes. Nanoscopic organic clusters, which initially coexist with the nanowires, vanish within hours. Thermal annealing of nanowire samples leads to even more pronounced morphology changes......, such as a strong decrease in nanowire number density, a strong increase in nanowire height, and the formation of new types of crystallites. This happens even before sublimation of organic material starts. These experiments also shine new light on the formation process of the nanowires....

  6. Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires.

    Science.gov (United States)

    Chong, Su Kong; Dee, Chang Fu; Abdul Rahman, Saadah

    2013-04-17

    Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO.

  7. Characterization of Co-existing In2O3-ZnO Nanostructures

    Science.gov (United States)

    Sarkar, K.; Mukherjee, S.; Farid, S.; Nicholls, A.; Stroscio, M. A.; Dutta, M.

    2017-10-01

    In this study, we report the simultaneous growth of both In2O3 and ZnO nanostructures on the same substrate when attempting to achieve heavily Zn-doped In2O3 nanowires with Zn. These oxide structures were synthesized by vapor-liquid-solid growth. Scanning electron microscope imaging and transmission electron microscopy shows the presence of nanostructures with different morphologies while energy-dispersive x-ray and x-ray photoelectron spectroscopy study confirms the elemental structure. Room-temperature photoluminescence (PL) study reveals the presence of oxygen vacancies and surface defects in the structures. Emission related to free and bound excitons as well as the donor-acceptor transitions were observed using temperature-dependent PL. Raman spectroscopy measurement using 442-nm non-resonant excitation sources shows the presence of four phonon modes associated with a cubic In2O3 lattice structure along with the observation of the dominant E 2 high and quasi-longitudinal optical phonon modes associated with wurtzite ZnO. We find that the introduction of high zinc content results in the formation of ZnO nanowires in addition to the In2O3 nanowires, and not the formation of a highly doped In2O3 nanowires.

  8. Sonochemical assisted synthesis of RGO/ZnO nanowire arrays for photoelectrochemical water splitting.

    Science.gov (United States)

    Khan, Ibrahim; Ibrahim, Akram A M; Sohail, Manzar; Qurashi, Ahsanulhaq

    2017-07-01

    This article presented the synthesis of a hybrid nanoarchitecture material composed of reduced graphene oxide (RGO) multiple sheets and ZnO nanowire arrays (NWAs) formed on an arbitrary ZnO coated fluorine doped tin oxide (FTO) substrates via pulse sonication and hydrothermal approach. The NWAs have high aspect-ratio, high density, apt positioning and well-ordered formation. FESEM images demonstrated that RGO layers have been effectively intercalated between and on the accessible surfaces of the ZnO NWAs. The diameter of ZnO nanowires is 80-150nm and length about 1-2μm. Raman spectrum of hybrid material exhibited characteristic D and suppressed G peaks for graphene and E 2 mode at 437cm -1 for ZnO NWAs. UV-visible spectrum indicated slight red shift towards visible range after formation of RGO/ZnO NWAs heterostructure. The Photoelectrochemical results indicated higher current densities for RGO/ZnO NWAs heterostructure due to water oxidation reaction at the working electrode compared to pristine ZnO NWAs. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. All oxide ultraviolet photodetectors based on a p-Cu{sub 2}O film/n-ZnO heterostructure nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ok, Yul Ho; Lee, Ki Ryong; Jung, Byung Oh; Kwon, Yong Hun; Cho, Hyung Koun, E-mail: chohk@skku.edu

    2014-11-03

    All-oxide ultraviolet (UV) photodetectors based on a p-Cu{sub 2}O thin film and n-ZnO nanowires were fabricated on Corning glass substrates. The p-Cu{sub 2}O film was fabricated by a sol–gel method and two-step thermal treatment on the ZnO nanowire arrays grown on ZnO doped with 5 at.% Al bottom electrode/glass for the formation of a p–n diode. The sol–gel coating of a Cu{sub 2}O layer produced the thin p-Cu{sub 2}O film with good uniformity on the ZnO nanowires and polycrystals with the (111) preferred orientation. It resulted in continuous interconnection of the ZnO nanowire arrays despite the solution process. The current–voltage (I–V) characteristics of the fabricated p–n heterostructure showed a typical rectifying behavior with a current rise at about 2 V and an I (illumination)/I (dark) ratio of about 3.89 × 10{sup 2} at − 6 V. The p-Cu{sub 2}O/n-ZnO nanowire-based UV photodetectors show the responsivity of ∼ 50 A/W with a peak position at 360 nm in reverse bias, together with weak photoresponse in the visible region. Consequently, we found that the introduction of the p-type Cu{sub 2}O layer in the ZnO nanowire-based UV photodetectors provided effective all-oxide p–n junctions without degrading UV/visible selectivity. - Highlights: • P-type Cu{sub 2}O films were deposited by a sol–gel method on the ZnO nanowires. • The p-Cu{sub 2}O/n-ZnO nanowire structure was fabricated for ultraviolet sensors. • Cu{sub 2}O films were optimized by spin coating speed and mole concentration. • Continuous Cu{sub 2}O films were produced as a hole injection or transport layer. • Cu{sub 2}O/ZnO nanowire photodetectors showed improved sensing performance.

  10. Strain analysis of nanowire interfaces in multiscale composites

    Science.gov (United States)

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

    2016-04-01

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

  11. One step biofunctionalized electrospun multiwalled carbon nanotubes embedded zinc oxide nanowire interface for highly sensitive detection of carcinoma antigen-125.

    Science.gov (United States)

    Paul, K Brince; Singh, Vikrant; Vanjari, Siva Rama Krishna; Singh, Shiv Govind

    2017-02-15

    Ovarian cancer is the most leading cause of cancer-related death in women . The carcinoma antigen-125, which is found on the surface of many ovarian cancer cells is known to be a gold standard clinical biomarker associated with life-threatening gynecological malignancy. In this work, we demonstrate a novel biosensor platform based on multiwalled carbon nanotubes embedded zinc oxide nanowire for the ultrasensitive detection of carcinoma antigen-125. Label free detection of the carcinoma antigen-125 was accomplished by differential voltammetry technique that demonstrated excellent sensitivity (90.14µA/(U/mL)/cm2) with a detection limit of 0.00113UmL-1 concentration. The fabricated immunosensor exhibits good performance with wider detection range (0.001UmL-1-1kUmL-1), reproducibility, selectivity, acceptable stability, and thus is a potential cost-effective methodology for point-of-care diagnosis. The multiwalled carbon nanotubes (MWCNTs) embedded highly oriented zinc oxide (ZnO) nanowires were synthesized by simple, low cost electrospinning technique. Compared to pure ZnO nanowires, electrochemical activity of MWCNTs embedded ZnO nanowires was found to be much higher. The calcination temperature was optimized to avoid any decomposition of the CNTs and to obtain multiwalled carbon nanotubes embedded highly crystalline ZnO nanowires. The salient feature of this biosensing platform is that one step calcination process is enough to create the functional groups on MWCNT-ZnO nanowire surface that are effective for the covalent conjugation of antibody without further surface modification. To the best of our knowledge, this is the first report on MWCNT-ZnO nanowire based immunosensor explored for the detection of cancer biomarker. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Advances in nanowire bioelectronics

    Science.gov (United States)

    Zhou, Wei; Dai, Xiaochuan; Lieber, Charles M.

    2017-01-01

    Semiconductor nanowires represent powerful building blocks for next generation bioelectronics given their attractive properties, including nanometer-scale footprint comparable to subcellular structures and bio-molecules, configurable in nonstandard device geometries readily interfaced with biological systems, high surface-to-volume ratios, fast signal responses, and minimum consumption of energy. In this review article, we summarize recent progress in the field of nanowire bioelectronics with a focus primarily on silicon nanowire field-effect transistor biosensors. First, the synthesis and assembly of semiconductor nanowires will be described, including the basics of nanowire FETs crucial to their configuration as biosensors. Second, we will introduce and review recent results in nanowire bioelectronics for biomedical applications ranging from label-free sensing of biomolecules, to extracellular and intracellular electrophysiological recording.

  13. The Assessment for Sensitivity of a NO2 Gas Sensor with ZnGa2O4/ZnO Core-Shell Nanowires—a Novel Approach

    Directory of Open Access Journals (Sweden)

    I-Cherng Chen

    2010-03-01

    Full Text Available The application of novel core-shell nanowires composed of ZnGa2O4/ZnO to improve the sensitivity of NO2 gas sensors is demonstrated in this study. The growth of ZnGa2O4/ZnO core-shell nanowires is performed by reactive evaporation on patterned ZnO:Ga/SiO2/Si templates at 600 °C. This is to form the homogeneous structure of the sensors investigated in this report to assess their sensitivity in terms of NO2 detection. These novel NO2 gas sensors were evaluated at working temperatures of 25 °C and at 250 °C, respectively. The result reveals the ZnGa2O4/ZnO core-shell nanowires present a good linear relationship (R2 > 0.99 between sensitivity and NO2 concentration at both working temperatures. These core-shell nanowire sensors also possess the highest response (<90 s and recovery (<120 s values with greater repeatability seen for NO2 sensors at room temperature, unlike traditional sensors that only work effectively at much higher temperatures. The data in this study indicates the newly-developed ZnGa2O4/ZnO core-shell nanowire based sensors are highly promising for industrial applications.

  14. The Assessment for Sensitivity of a NO2 Gas Sensor with ZnGa2O4/ZnO Core-Shell Nanowires—a Novel Approach

    Science.gov (United States)

    Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Hsu, Cheng-Liang; Hsueh, Ting Jen; Shieh, Tien-Yu

    2010-01-01

    The application of novel core-shell nanowires composed of ZnGa2O4/ZnO to improve the sensitivity of NO2 gas sensors is demonstrated in this study. The growth of ZnGa2O4/ZnO core-shell nanowires is performed by reactive evaporation on patterned ZnO:Ga/SiO2/Si templates at 600 °C. This is to form the homogeneous structure of the sensors investigated in this report to assess their sensitivity in terms of NO2 detection. These novel NO2 gas sensors were evaluated at working temperatures of 25 °C and at 250 °C, respectively. The result reveals the ZnGa2O4/ZnO core-shell nanowires present a good linear relationship (R2 > 0.99) between sensitivity and NO2 concentration at both working temperatures. These core-shell nanowire sensors also possess the highest response (ZnGa2O4/ZnO core-shell nanowire based sensors are highly promising for industrial applications. PMID:22319286

  15. The effect of Cu doping on the mechanical and optical properties of zinc oxide nanowires synthesized by hydrothermal route

    Science.gov (United States)

    Robak, Elżbieta; Coy, Emerson; Kotkowiak, Michał; Jurga, Stefan; Załęski, Karol; Drozdowski, Henryk

    2016-04-01

    Zinc oxide (ZnO) is a wide-bandgap semiconductor material with applications in a variety of fields such as electronics, optoelectronic and solar cells. However, much of these applications demand a reproducible, reliable and controllable synthesis method that takes special care of their functional properties. In this work ZnO and Cu-doped ZnO nanowires are obtained by an optimized hydrothermal method, following the promising results which ZnO nanostructures have shown in the past few years. The morphology of as-prepared and copper-doped ZnO nanostructures is investigated by means of scanning electron microscopy and high resolution transmission electron microscopy. X-ray diffraction is used to study the impact of doping on the crystalline structure of the wires. Furthermore, the mechanical properties (nanoindentation) and the functional properties (absorption and photoluminescence measurements) of ZnO nanostructures are examined in order to assess their applicability in photovoltaics, piezoelectric and hybrids nanodevices. This work shows a strong correlation between growing conditions, morphology, doping and mechanical as well as optical properties of ZnO nanowires.

  16. Lasing and ion beam doping of semiconductor nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Geburt, Sebastian

    2013-01-31

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

  17. New Theoretical Results for High Diffusive Nanosensors Based on ZnO Oxides

    Directory of Open Access Journals (Sweden)

    Paolo DI SIA

    2010-11-01

    Full Text Available The approach for converting nanoscale mechanical energy into electrical energy using piezoelectric zinc oxide (ZnO nanowire arrays has been broadly shown by deflection of the nanowires via a corrugated electrode operated up and down by ultrasounds. From a theoretical viewpoint, we have performed an analytical method for describing the most important quantities concerning transport phenomena. This method predicts very high initial diffusion of charge via mechanical external device stresses, assuming therefore the typical characteristics of a nanosensor. With this model it is possible to deduce important information about the device sensitivity, focusing on the interesting correlation between sensitivity and high initial diffusivity of these materials at nanometric state.

  18. Optical properties of ZnO/ZnMgO nanowire heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, Nils; Cichos, Frank [Molecular Nanophotonics Group, University of Leipzig, Linnestrasse 5, 04103 Leipzig (Germany); Cao, Bingqiang; Grundmann, Marius [Semiconductor Physics Group, University of Leipzig, Linnestrasse 5, 04103 Leipzig (Germany)

    2011-07-01

    ZnO nanowires are promising candidates for the fabrication of nanoscaled light emitting devices. Due to the large energy bandgap and exciton binding energy of ZnO, it offers the possibility for nanoscale light emitters in the UV spectral region working at room temperature. Pulsed laser deposition (PLD) enables the growth of defined nanowire shapes and nano-heterostructures to modify their optical properties. Due to quantum confinement effects in such heterostructures even single-photon emission is possible, a key requirement for future communication technologies like quantum cryptography. We have investigated ZnO nanowires with a radial and axial ZnO/ZnMgO quantum well heterostructure. These core/shell nanostructures were grown by a two step PLD process, which leads to a low area-density of the nanowires to provide homogeneous growth of the quantum well heterostructures. Optical studies were carried out in a photoluminescence setup. Excitation is done with a frequency quadrupled Nd:YVO{sub 4} laser in a TIRF (Total Internal Reflection Fluorescence) configuration. The emitted light is collected confocally and is detected in a Hanbury Brown-Twiss setup to study photon correlations.

  19. Regular ZnO nanopillar arrays by nanosphere photolithography

    Science.gov (United States)

    Szabó, Z.; Volk, J.; Fülöp, E.; Deák, A.; Bársony, I.

    2013-02-01

    Highly regular vertical ZnO nanopillar arrays were hydrothermally grown through a nucleation window pattern generated by nanosphere photolithography. The in-plane intensity modulation of the exposing ultraviolet light in the photoresist was performed by Stöber silica or polystyrene nanospheres in the masking Langmuir-Blodgett monolayer. By comparing six different nanosphere diameters in the 180-700 nm range only those with diameter above the exposure wavelength of 405 nm generate a pattern in the thin photoresist layer. The pattern quality is improving with increasing diameter, therefore, the masking for nanopillar growth was demonstrated with 700 nm polystyrene nanospheres. The results of the nanosphere photolithography were supported by finite-difference time-domain calculations. This growth approach was shown to have the potential for low-cost, low-temperature, large area fabrication of ZnO pillars or nanowires enabling a precise engineering of geometry.

  20. Construction of CuO/In2S3/ZnO heterostructure arrays for enhanced photocatalytic efficiency.

    Science.gov (United States)

    Chang, Yu-Cheng; Guo, Jin-You; Chen, Chien-Ming; Di, Hsin-Wei; Hsu, Chao-Chun

    2017-09-14

    Novel one-dimensional (1D) heterostructure arrays composed of CuO nanowire cores, intermediate In 2 S 3 nanostructures, and ZnO nanorod sheaths (i.e. CuO/In 2 S 3 /ZnO heterostructure arrays) have been successfully synthesized by a multi-step process. First, single-crystalline CuO nanowires were directly grown on flexible Cu mesh substrates using a one-step annealing process under ambient conditions. Second, In 2 S 3 nanostructures and ZnO nanorods were sequentially grown on the CuO nanowires by a two-step hydrothermal method at low reaction temperature. The morphology, crystal structures, and optical properties of the CuO/In 2 S 3 /ZnO heterostructure arrays were studied by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive spectroscopy, and photoluminescence spectroscopy. The resultant ternary CuO/In 2 S 3 /ZnO heterostructure arrays exhibit excellent photocatalytic activity in the photodegradation of rhodamine 6G (R6G) under 10 W UV light irradiation, which is much higher than that of single-component (CuO nanowire arrays) or two-component systems (CuO/In 2 S 3 heterostructure arrays). Furthermore, the reusability test demonstrates that the CuO/In 2 S 3 /ZnO heterostructure arrays on the Cu mesh still maintain high photocatalytic activity in the degradation of three kinds of organic pollutants even after five cycles, without any significant decline. These findings provide an insight into the design and synthesis of new CuO-based composites to effectively improve their photocatalytic performance.

  1. Fluorinated copper phthalocyanine nanowires for enhancing interfacial electron transport in organic solar cells.

    Science.gov (United States)

    Yoon, Seok Min; Lou, Sylvia J; Loser, Stephen; Smith, Jeremy; Chen, Lin X; Facchetti, Antonio; Marks, Tobin J; Marks, Tobin

    2012-12-12

    Zinc oxide is a promising candidate as an interfacial layer (IFL) in inverted organic photovoltaic (OPV) cells due to the n-type semiconducting properties as well as chemical and environmental stability. Such ZnO layers collect electrons at the transparent electrode, typically indium tin oxide (ITO). However, the significant resistivity of ZnO IFLs and an energetic mismatch between the ZnO and the ITO layers hinder optimum charge collection. Here we report that inserting nanoscopic copper hexadecafluorophthalocyanine (F(16)CuPc) layers, as thin films or nanowires, between the ITO anode and the ZnO IFL increases OPV performance by enhancing interfacial electron transport. In inverted P3HT:PC(61)BM cells, insertion of F(16)CuPc nanowires increases the short circuit current density (J(sc)) versus cells with only ZnO layers, yielding an enhanced power conversion efficiency (PCE) of ∼3.6% vs ∼3.0% for a control without the nanowire layer. Similar effects are observed for inverted PTB7:PC(71)BM cells where the PCE is increased from 8.1% to 8.6%. X-ray scattering, optical, and electrical measurements indicate that the performance enhancement is ascribable to both favorable alignment of the nanowire π-π stacking axes parallel to the photocurrent flow and to the increased interfacial layer-active layer contact area. These findings identify a promising strategy to enhance inverted OPV performance by inserting anisotropic nanostructures with π-π stacking aligned in the photocurrent flow direction.

  2. The interplay of structural and optical properties in individual ZnO nanostructures

    Science.gov (United States)

    Brewster, Megan M.; Zhou, Xiang; Lu, Ming-Yen; Gradečak, Silvija

    2012-02-01

    Semiconductor nanostructures exhibit unique properties distinct from their bulk counterparts by virtue of nanoscale dimensions; in particular, exceptionally large surface area-to-volume ratios relative to that of the bulk produce variations in surface state populations that have numerous consequences on materials properties. Of the low-dimensional semiconductor nanostructures, nanowires offer a unique prospect in nanoscale optoelectronics due to their one-dimensional architecture. Already, many devices based upon individual nanowires have been demonstrated, but questions about how nano-size and structural variations affect the underlying materials properties still remain unanswered. Here, we focus on understanding the growth mechanism and kinetics of ZnO nanowires and related nanowalls, and their effects on nanoscale structural and optical properties.Semiconductor nanostructures exhibit unique properties distinct from their bulk counterparts by virtue of nanoscale dimensions; in particular, exceptionally large surface area-to-volume ratios relative to that of the bulk produce variations in surface state populations that have numerous consequences on materials properties. Of the low-dimensional semiconductor nanostructures, nanowires offer a unique prospect in nanoscale optoelectronics due to their one-dimensional architecture. Already, many devices based upon individual nanowires have been demonstrated, but questions about how nano-size and structural variations affect the underlying materials properties still remain unanswered. Here, we focus on understanding the growth mechanism and kinetics of ZnO nanowires and related nanowalls, and their effects on nanoscale structural and optical properties. This article was submitted as part of a collection highlighting papers on the `Recent Advances in Semiconductor Nanowires Research' from ICMAT 2011.

  3. Al-doped ZnO/Ag-nanowire Composite Electrodes for Flexible 3-Dimensional Nanowire Solar Cells.

    Science.gov (United States)

    Pathirane, Minoli K; Hosseinzadeh Khaligh, Hadi; Goldthorpe, Irene A; Wong, William S

    2017-08-21

    Silver nanowires in conjunction with sputter-coated Al-doped ZnO (AZO) thin films were used as a composite transparent top electrode for hybrid radial-junction ZnO nanowire/a-Si:H p-i-n thin-film solar cells. Solar cells with the composite nanowire top contacts attained a short-circuit current density (Jsc) of 13.9 mA/cm2 and a fill factor (FF) of 62% on glass substrates while a Jsc of 13.0 mA/cm2 and FF of 62% was achieved on plastic substrates. The power conversion efficiency (PCE) of the 3-dimensional solar cells improved by up to 60% compared to using AZO electrodes alone due to enhanced coverage of the top electrode over the 3-D structures, decreasing the series resistance of the device by 5×. The composite layer also showed a 10× reduction in sheet resistance compared to the AZO thin-film contact under applied mechanical strain.

  4. Nanowire Photovoltaic Devices

    Science.gov (United States)

    Forbes, David

    2015-01-01

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

  5. Metallic nanowire networks

    Science.gov (United States)

    Song, Yujiang; Shelnutt, John A.

    2012-11-06

    A metallic nanowire network synthesized using chemical reduction of a metal ion source by a reducing agent in the presence of a soft template comprising a tubular inverse micellar network. The network of interconnected polycrystalline nanowires has a very high surface-area/volume ratio, which makes it highly suitable for use in catalytic applications.

  6. Nanowire Growth for Photovoltaics

    DEFF Research Database (Denmark)

    Holm, Jeppe Vilstrup

    the small footprint of grown nanowires relaxes the crystal matching constraint. 1.7eV is the ideal bandgap for a top junction in a dual junction solar cell, where silicon is the bottom junction. This can be obtained with GaAs0.8P0.2. We have demonstrated how to incorporate phosphorous(P) into Ga......-catalyzed nanowire growth, and grown GaAs1−xPx nanowires with different inclusions of P(x) directly on silicon. The incorporation of P was generally higher in nanowires than for planar growth at identical P flux percentage. More interestingly, the percentage of P in the nanowire was found to be a concave function...

  7. Graphene oxide sheets involved in vertically aligned zinc oxide nanowires for visible light photoinactivation of bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Nourmohammadi, Amin; Rahighi, Reza [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Akhavan, Omid, E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of); Moshfegh, Alireza [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2014-11-05

    Highlights: • Involvement of GO into the vertically aligned ZnO nanowires using electrophoretic deposition. • UV assisted photocatalytic reduction of the GO sheets involved in the ZnO nanowires. • Visible light photoinactivation of bacteria by the reduced graphene oxide/ZnO nanocomposite. - Abstract: Vertically aligned ZnO nanowires (NWs) hybridized with reduced graphene oxide sheets (rGO) were applied in efficient visible light photoinactivation of bacteria. To incorporate graphene oxide (GO) sheets within the NWs two different methods of drop-casting and electrophoretic deposition (EPD) were utilized. The EPD method yielded effective penetration of the positively charged GO sheets into the NWs to form a spider net-like structure, whereas the drop-casting method resulted in only a surface coverage of the GO sheets on top of the NWs. The electrical connection between the EPD-incorporated sheets and the NWs was checked by monitoring the electron transfer from UV-assisted photoexcited ZnO NWs into the GO sheets, during photocatalytic reduction of the sheets. The obtained rGO/ZnO composites were applied in visible light photoinactivation of Escherichia coli bacteria. The ZnO NWs could inactivate only ∼58% of the bacteria, while both drop-casting and EPD-prepared GO/ZnO composites exhibited strong antibacterial activities (especially the EPD sample with ∼99.5% photoinactivation), under visible light irradiation for 1 h. In fact, the visible light photocatalytic activity of the EPD-prepared GO/ZnO NW composite was found ∼1.9 and 6.2 folds of the activity of the GO/ZnO composite prepared by drop-casting method and the bare ZnO NWs.

  8. Aligned hierarchical Ag/ZnO nano-heterostructure arrays via electrohydrodynamic nanowire template for enhanced gas-sensing properties.

    Science.gov (United States)

    Yin, Zhouping; Wang, Xiaomei; Sun, Fazhe; Tong, Xiaohu; Zhu, Chen; Lv, Qiying; Ye, Dong; Wang, Shuai; Luo, Wei; Huang, YongAn

    2017-09-22

    Gas sensing performance can be improved significantly by the increase in both the effective gas exposure area and the surface reactivitiy of ZnO nanorods. Here, we propose aligned hierarchical Ag/ZnO nano-heterostructure arrays (h-Ag/ZnO-NAs) via electrohydrodynamic nanowire template, together with a subsequent hydrothermal synthesis and photoreduction reaction. The h-Ag/ZnO-NAs scatter at top for higher specific surface areas with the air, simultaneously contact at root for the electrical conduction. Besides, the ZnO nanorods are uniformly coated with dispersed Ag nanoparticles, resulting in a tremendous enhancement of the surface reactivity. Compared with pure ZnO, such h-Ag/ZnO-NAs exhibit lower electrical resistance and faster responses. Moreover, they demonstrate enhanced NO 2 gas sensing properties. Self-assembly via electrohydrodynamic nanowire template paves a new way for the preparation of high performance gas sensors.

  9. An investigation into the role of polyethyleneimine in chemical bath deposition of zinc oxide nanowires

    Science.gov (United States)

    Eskandari, Alireza; Abdizadeh, Hossein; Pourshaban, Erfan; Golobostanfard, Mohammad Reza

    2018-01-01

    Zinc oxide nanowires are considered as promising materials for wide range of optoelectrical and chemical devices, thanks to their desirable structural and optoelectrical properties. Over the past decade, chemical bath deposition (CBD) has been widely used to synthesize these nanostructures due to its low cost and controllability. Since improving the aspect ratio and length of nanowires is a vital issue in growing one-dimensional nanostructures, the influence of polyethyleneimine (PEI) as a complexing and chelating agent on the structural, morphological, and optoelectrical properties of ZnO nanowires has been studied in this report. As-grown ZnO nanowires synthesized by mixing deionized water, zinc acetate dihydrate, hexamethylenetetramine, and PEI were characterized with field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD), and photoluminescence spectroscopy (PL). FESEM results unambiguously show that increasing PEI concentration (from 0 to 0.2 g in 50 ml DI water) reduces the diameter and density of nanowires from ˜120 to 56 nm and from ˜85% to 65%, respectively. Interestingly, although adding more PEI decreases nanowires diameter, over-increasing of PEI brings about an inappropriate nanostructures growth. Moreover, XRD patterns demonstrate that all the samples have wurtzite structure with a preferred orientation along c-axis which may be improved or deteriorated by adding PEI into the chemical bath. Accordingly, it is crucial to optimize the amount of PEI in CBD method. Near-band edge (NBE) region in PL spectrum also confirms wide bandgap of ZnO (˜3.3 eV). In addition, comparing the appearance of PEI free with PEI assisted solutions show a considerable difference in their colors, which may be attributed to the formation of new chemical compounds. Considering these results, PEI plays a couple of determining roles in synthesizing ZnO nanowires; making nanowires thinner, with selectively absorption to the non-polar, lateral facets of

  10. Self-assembled, nanowire network electrodes for depleted bulk heterojunction solar cells

    KAUST Repository

    Lan, Xinzheng

    2013-01-06

    Herein, a solution-processed, bottom-up-fabricated, nanowire network electrode is developed. This electrode features a ZnO template which is converted into locally connected, infiltratable, TiO2 nanowires. This new electrode is used to build a depleted bulk heterojunction solar cell employing hybrid-passivated colloidal quantum dots. The new electrode allows the application of a thicker, and thus more light-absorbing, colloidal quantum dot active layer, from which charge extraction of an efficiency comparable to that obtained from a thinner, planar device could be obtained. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yamin, E-mail: yaminfengccnuphy@outlook.com; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang, E-mail: xthuang@phy.ccnu.edu.cn

    2013-12-25

    Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm{sup −2} illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes.

  12. Nanowire Growth for Photovoltaics

    DEFF Research Database (Denmark)

    Holm, Jeppe Vilstrup

    cells. Resonance effects between the light and nanowire causes an inherent concentration of the sunlight into the nanowires, and means that a sparse array of nanowires (less than 5% of the area) can absorb all the incoming light. The resonance effects, as well as a graded index of refraction, also traps...... of the percentage of P in the flux, while for planar growth it was a convex function. We have demonstrated GaAs0.8P0.2 nanowires and further grown a shell surrounding the core with the same composition. The lattice matched GaAsP core-shell nanowire were doped to produce radial p-i-n junctions in each...... of the nanowires, some of which were removed from their growth substrate and turned into single nanowire solar cells (SNWSC). The best device showed a conversion efficiency of 6.8% under 1.5AMG 1-sun illumination. In order to improve the efficiency a surface passivating shell consisting of highly doped, wide...

  13. Nanowire-based thermoelectrics

    Science.gov (United States)

    Ali, Azhar; Chen, Yixi; Vasiraju, Venkata; Vaddiraju, Sreeram

    2017-07-01

    Research on thermoelectrics has seen a huge resurgence since the early 1990s. The ability of tuning a material’s electrical and thermal transport behavior upon nanostructuring has led to this revival. Nevertheless, thermoelectric performances of nanowires and related materials lag far behind those achieved with thin-film superlattices and quantum dot-based materials. This is despite the fact that nanowires offer many distinct advantages in enhancing the thermoelectric performances of materials. The simplicity of the strategy is the first and foremost advantage. For example, control of the nanowire diameters and their surface roughnesses will aid in enhancing their thermoelectric performances. Another major advantage is the possibility of obtaining high thermoelectric performances using simpler nanowire chemistries (e.g., elemental and binary compound semiconductors), paving the way for the fabrication of thermoelectric modules inexpensively from non-toxic elements. In this context, the topical review provides an overview of the current state of nanowire-based thermoelectrics. It concludes with a discussion of the future vision of nanowire-based thermoelectrics, including the need for developing strategies aimed at the mass production of nanowires and their interface-engineered assembly into devices. This eliminates the need for trial-and-error strategies and complex chemistries for enhancing the thermoelectric performances of materials.

  14. Metal oxide nanowire growth for nanotechnology-enhanced device applications

    Science.gov (United States)

    Oye, M. M.; Gacusan, J.; Lenz, O.; Ngo-Duc, T.; Velazquez, J. M.; Arreola, E.; Jethani, H.; Rohovie, M.; Gigante, B.; Kar, A.; Kim, B.; Hannon, A.; Savvinov, A.; Lu, Y.; Li, Ji.; Meyyappan, M.

    2011-10-01

    This paper presents our on-going nano-epitaxial efforts to grow tin oxide (SnO2), zinc oxide (ZnO), and lead zirconate titanate (PZT) for nanotechnology-enhanced devices. The applicable devices involve piezoelectric energy harvesting devices and nanomaterial-enhanced chemical sensors, with the Systems-level vision involving the piezoelectric energy harvesting devices that could self-power chemical sensors for a stand-alone, self-powered device that could harvest its own power from mechanical vibrations. To this end, device concepts are presented herein and preliminary details for ZnO, SnO2, and PZT material synthesis are presented. The growth of nanowires and nanotetrapods are presented for said device applications using vapor-liquid-solid (VLS), solution synthesis, as well as the results from other synthesis processes. Characterization was done by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

  15. ZnO Quasi-1D Nanostructures: Synthesis, Modeling, and Properties for Applications in Conductometric Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Vardan Galstyan

    2016-03-01

    Full Text Available One-dimensional metal oxide nanostructures such as nanowires, nanorods, nanotubes, and nanobelts gained great attention for applications in sensing devices. ZnO is one of the most studied oxides for sensing applications due to its unique physical and chemical properties. In this paper, we provide a review of the recent research activities focused on the synthesis and sensing properties of pure, doped, and functionalized ZnO quasi-one dimensional nanostructures. We describe the development prospects in the preparation methods and modifications of the surface structure of ZnO, and discuss its sensing mechanism. Next, we analyze the sensing properties of ZnO quasi-one dimensional nanostructures, and summarize perspectives concerning future research on their synthesis and applications in conductometric sensing devices.

  16. 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.

  17. Aluminum as catalyst for ZnO nanostructures growth

    Energy Technology Data Exchange (ETDEWEB)

    Zandalazini, C., E-mail: zc@famaf.unc.edu.ar [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Villafuerte, M. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Oliva, M. [Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Grupo de Ciencia de Materiales, Facultad de Matemática, Astronomía, y Física, Universidad Nacional de Córdoba (Argentina); Heluani, S.P. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina)

    2015-05-15

    Highlights: • The efficiency of aluminum as catalyst to grow ZnO nanostructures is proved. • Aluminum as a new catalyst is proposed due to its reduced economic cost. • VSS growth mechanism is the main mechanism using Al as catalyst. • Abrupt diameter change of NWs is discussed due to Al-assisted growth. - Abstract: We report the growth of Al-catalyzed ZnO nanowires (NWs) using a thermal evaporation technique. Before the growth, the substrates were covered with a distribution of Al nano-island that act as seeds. We found that the density of NWs increases as the density of seeds is increased, confirming the catalyst properties of Al. The critical parameters of growth are the substrate temperature, oxygen partial pressure and the thickness of the initial Al layer from which the seeds are formed. The results showed that the oxygen pressure has a strong influence on the structural characteristics: the nanowires exhibit a preferential orientation in the (0 0 l)-planes when they are grown at low oxygen flow, and they become polycrystalline when a high concentration of oxygen in the flow is used. We consider that the growth occurs via a vapor-solid-solid (VSS) process as the predominant growth mechanism.

  18. Fabricating ZnO single microwire light-emitting diode with transparent conductive ITO film

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yingtian [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Dai, Jun [State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096 (China); Shi, Zhifeng [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Long, Beihong [College of Materials Science and Engineering, Jinlin University, 2699 Qianjin Street, Changchun 130012 (China); Wu, Bin; Cai, Xupu; Chu, Xianwei; Du, Guotong; Zhang, Baolin [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Yin, Jingzhi, E-mail: yjz886666@163.com [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2014-05-01

    In this paper, n-ZnO single microwire/p{sup +}-Si heterojunction LEDs are fabricated using the transparent conductive ITO film as an electrode. A distinct UV emission resulting from free exciton recombination in a ZnO single microwire is observed in the electroluminescence. Size difference of ZnO single microwire shows significant influence on emission efficiency. The EL spectra of n-ZnO single microwire/p-Si heterostructure exhibited relatively stronger UV emission which was compared with the EL spectra of n-ZnO single nanowire/p-Si heterostructure and n-ZnO film/p-Si heterostructure, respectively. - Highlights: • The ZnO microwires were synthesized with a vapor phase transport method. • ZnO single microwire/Si LEDs were fabricated using the ITO film as an electrode. • The EL spectra had been compared with n-ZnO film/p-Si heterostructure. • The EL spectra had been compared with n-ZnO single nanowire/p-Si heterostructure.

  19. Mechanism and Growth of Flexible ZnO Nanostructure Arrays in a Facile Controlled Way

    Directory of Open Access Journals (Sweden)

    Yangping Sheng

    2011-01-01

    Full Text Available Nanostructure arrays-based flexible devices have revolutionary impacts on the application of traditional semiconductor devices. Here, a one-step method to synthesize flexible ZnO nanostructure arrays on Zn-plated flexible substrate in Zn(NO32/NH3⋅H2O solution system at 70–90∘C was developed. We found out that the decomposition of Zn(OH2 precipitations, formed in lower NH3⋅H2O concentration, in the bulk solution facilitates the formation of flower-like structure. In higher temperature, 90∘C, ZnO nanoplate arrays were synthesized by the hydrolysis of zinc hydroxide. Highly dense ZnO nanoparticale layer formed by the reaction of NH3⋅H2O with Zn plating layer in the initial self-seed process could improve the vertical alignment of the nanowires arrays. The diameter of ZnO nanowire arrays, from 200 nm to 60 nm, could be effectively controlled by changing the stability of Zn(NH342+ complex ions by varying the ratio of Zn(NO32 to NH3⋅H2O which further influence the release rate of Zn2+ ions. This is also conformed by different amounts of the Zn vacancy as determined by different UV emissions of the PL spectra in the range of 380–403 nm.

  20. Growth of ZnO nanotube arrays and nanotube based piezoelectric nanogenerators

    KAUST Repository

    Xi, Yi

    2009-01-01

    We present a systematic study of the growth of hexagonal ZnO nanotube arrays using a solution chemical method by varying the growth temperature (<100 °C), time and solution concentration. A piezoelectric nanogenerator using the as-grown ZnO nanotube arrays has been demonstrated for the first time. The nanogenerator gives an output voltage up to 35 mV. The detailed profile of the observed electric output is understood based on the calculated piezoelectric potential in the nanotube with consideration of the Schottky contact formed between the metal tip and the nanotube; and the mechanism agrees with that proposed for nanowire based nanogenerator. Our study shows that ZnO nanotubes can also be used for harvesting mechanical energy. © 2009 The Royal Society of Chemistry.

  1. The electronic structures of AlN and InN wurtzite nanowires

    Science.gov (United States)

    Xiong, Wen; Li, Dong-Xiao

    2017-07-01

    We derive the relations between the analogous seven Luttinger-Kohn parameters and six Rashba-Sheka-Pikus parameters for wurtzite semiconductors, which can be used to investigate the electronic structures of some wurtzite semiconductors such as AlN and InN materials, including their low-dimensional structures. As an example, the electronic structures of AlN and InN nanowires are calculated by using the derived relations and six-band effective-mass k · p theory. Interestingly, it is found that the ground hole state of AlN nanowires is always a pure S state whether the radius R is small (1 nm) or large (6 nm), and the ground hole state only contains | Z > Bloch orbital component. Therefore, AlN nanowires is the ideal low-dimensional material for the production of purely linearly polarized π light, unlike ZnO nanowires, which emits plane-polarized σ light. However, the ground hole state of InN nanowires can be tuned from a pure S state to a mixed P state when the radius R is larger than 2.6 nm, which will make the polarized properties of the lowest optical transition changes from linearly polarized π light to plane-polarized σ light. Meanwhile, the valence band structures of InN nanowires will present strong band-crossings when the radius R increases to 6 nm, and through the detail analysis of possible transitions of InN nanowires at the Γ point, we find some of the neighbor optical transitions are almost degenerate, because the spin-orbit splitting energy of InN material is only 0.001 eV. Therefore, it is concluded that the electronic structures and optical properties of InN nanowires present great differences with that of AlN nanowires.

  2. Porous Silicon Nanowires

    Science.gov (United States)

    Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

    2011-01-01

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

  3. Ballistic Majorana nanowire devices

    NARCIS (Netherlands)

    Gül, Önder

    2017-01-01

    The dissertation reports a series of electron transport experiments on semiconductor nanowires towards realizing the hypothesized topological quantum computation. A topological quantum computer manipulates information that is stored nonlocally in the topology of a physical system. Such an operation

  4. Biofunctionalized Magnetic Nanowires

    KAUST Repository

    Kosel, Jurgen

    2013-12-19

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

  5. Temperature dependent current transport of Pd/ZnO nanowire Schottky diodes

    Science.gov (United States)

    Gayen, R. N.; Bhattacharyya, S. R.; Jana, P.

    2014-09-01

    Zinc oxide (ZnO) nanowire based Schottky barrier diodes are fabricated by depositing Pd metal contact on top of vertically well-aligned ZnO nanowire arrays. A vertical array of ZnO nanowires on indium tin oxide (ITO) coated glass substrates is synthesized by hybrid wet chemical route. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) measurement confirm the formation of stoichiometric well-aligned hexagonal (h-ZnO) nanowire arrays with wurtzite structure. Temperature dependent current-voltage (I-V) measurements on palladium-ZnO (Pd/ZnO) nanowire Schottky junctions in the temperature range 303-383 K exhibit excellent rectifying character. From these nonlinear I-V plots, different electrical parameters of diode-like reverse saturation current, barrier height and ideality factor are determined as a function of temperature assuming pure thermionic emission model. The ideality factor is found to decrease while the barrier height increases with the increase in temperature. The series resistance values calculated from Cheung’s functions also show temperature dependency. Such behavior can be attributed to the presence of defects that traps carriers, and barrier height inhomogeneity at the interface of the barrier junction. After barrier height inhomogeneity correction, considering a Gaussian distributed barrier height fluctuation across the Pd/ZnO interface, the estimated values of mean barrier height and modified Richardson constant are more closely matched to the theoretically predicted value for Pd/ZnO Schottky barrier diodes. The variation of density of interface states as a function of interface state energy is also calculated.

  6. Cleaved-Coupled Nanowire Lasers

    Science.gov (United States)

    2013-01-15

    fabricated with micrometer -scale gaps (26, 27). This Fig. 1. Single-frequency lasing in 9-μm (4:3) cleaved-coupled nanowires. (A) SEM images showing the...modulation of modes observed in cleaved-coupled nanowire lasers can be predicted using transfer matrix methods. Although the Vernier effect provides an...Following the Vernier effect, coupled nanowires with integer ratios would produce the free spectral range of the shorter nanowire. The lasing spectra

  7. Fletching-shaped Bi4Te3–ZnTe heterostructure nanowires.

    Science.gov (United States)

    Song, Man Suk; Kim, Yong

    2014-12-19

    We investigated Bi(4)Te(3)-ZnTe axial heterostructure nanowires grown by physical vapor transport at the substrate temperature of 450 °C, utilizing ZnTe as the source and Bi(2)Te(3) as the catalyst. The temperatures of the source and catalyst materials were individually controlled by separating the source and catalyst boats. The axial heterostructure nanowires consisted of ZnTe and Bi(4)Te(3) segments. The Bi(4)Te(3) segment had an interesting fletching shape with three wings surrounded by a ZnO shell. A systematic redshift in the nanowire's photoluminescence was observed as the excitation laser spot was moved from the heterojunction toward the root of the ZnTe segment, attributed to the formation of deep defect states under the Te-rich environment that resulted from using Bi(2)Te(3) as the catalyst instead of Bi.

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

    Directory of Open Access Journals (Sweden)

    Aaretti Kaleva

    2017-07-01

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

  9. Formation of p-Si/ZnO nanowire heterostructures for light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Haj Hmeidi, Yaser; Niepelt, Raphael; Gnauck, Martin; Schmidl, Frank; Ronning, Carsten [Institut fuer Festkoerperphysik, Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2011-07-01

    The development of scalable techniques for assembling nanowire devices needs practical circuits, which are highly parallel and reproducible overlarge areas. ZnO nanowires can be grown easily via vapor-liquid-solid (VLS) mechanism and are suitable for this application. Furthermore, they have an emission wavelength in the UV, but p-type doping is not possible so far. Therefore, light emitting devices must be based on heterostructures with other suitable p-type materials. In this presentation, we demonstrate p-n heterojunctions between n-type ZnO nanowires and highly doped p-type Si substrates. We developed a simple and powerful approach on the basis of spin-on-glass SiO{sub 2}. This approach is intrinsically scalable since every step involved can be carried out in parallel over an entire wafer. The challenge in this particular geometry is the fabrication of top metallic contacts on top of the nanowires in a way that the contact dose not short with the substrate. The resulting devices exhibit rectifying properties and under certain conditions, also light emission.

  10. Wire-shaped quantum dots-sensitized solar cells based on nanosheets and nanowires.

    Science.gov (United States)

    Chen, Haining; Zhu, Liqun; Wang, Meng; Liu, Huicong; Li, Weiping

    2011-11-25

    Wire-shaped quantum dots-sensitized solar cells (WS-QDSCs) based on nanosheets and nanowires were fabricated and investigated for this paper. The nanosheets grown on stainless steel (SS) wire by electrodeposition were mainly composed of Zn₅(OH)₈Cl₂·H₂O and most of the Zn₅(OH)₈Cl₂·H₂O was converted to ZnO by post-treatment, and ZnO nanowires were directly grown on SS wire by the hydrothermal method. CdS QDs were deposited on nanosheets and nanowires by successive ionic layer adsorption and reaction method. The results of photoelectrochemical performance indicated that WS-QDSCs showed a similar conversion efficiency in polysulfide and Na₂SO₄ electrolytes, while the WS-QDSCs based on the Cu2S counter electrode achieved much higher performance than those based on SS and Cu counter electrodes. By optimizing electrodeposition duration, the WS-QDSCs based on nanosheets presented the highest conversion efficiency of 0.60% for the duration of 20 min. Performance comparison indicated that the WS-QDSC based on nanosheets showed very superior performance to that based on the nanowires with similar film thickness.

  11. Giant piezoelectric size effects in zinc oxide and gallium nitride nanowires. A first principles investigation.

    Science.gov (United States)

    Agrawal, Ravi; Espinosa, Horacio D

    2011-02-09

    Nanowires made of materials with noncentrosymmetric crystal structure are under investigation for their piezoelectric properties and suitability as building blocks for next-generation self-powered nanodevices. In this work, we investigate the size dependence of piezoelectric coefficients in nanowires of two such materials - zinc oxide and gallium nitride. Nanowires, oriented along their polar axis, ranging from 0.6 to 2.4 nm in diameter were modeled quantum mechanically. A giant piezoelectric size effect is identified for both GaN and ZnO nanowires. However, GaN exhibits a larger and more extended size dependence than ZnO. The observed size effect is discussed in the context of charge redistribution near the free surfaces leading to changes in local polarization. The study reveals that local changes in polarization and reduction of unit cell volume with respect to bulk values lead to the observed size effect. These results have strong implication in the field of energy harvesting, as piezoelectric voltage output scales with the piezoelectric coefficient.

  12. Zinc oxide nanowires on carbon microfiber as flexible gas sensor

    Science.gov (United States)

    Tonezzer, M.; Lacerda, R. G.

    2012-03-01

    In the past years, zinc oxide nanowires (ZnO NWs) have been proven to be an excellent material for gas sensors. In this work, we used ZnO nanowires in a novel architecture integrated on a carbon microfiber (μC) textile. This innovative design permits us to obtain mechanical flexibility, while the absence of any lithographic technique allows a large-area and low-cost fabrication of gas sensors. The performances of the devices are investigated for both oxidizing and reducing gases. The nano-on-micro structure of the sensor provides a high surface-to-volume ratio, leading to a fast and intense response for both oxygen (O2) and hydrogen (H2) gases. The sensor response has an optimum temperature condition at 280 °C with a response value of 10 for oxygen and 11 for hydrogen. The limit of detection (LoD) has been found to be 2 and 4 ppm for oxygen and hydrogen, respectively. Additionally, the sensor response and recovery time is small being less than 10 s for both O2 and H2.

  13. Nanowire mesh solar fuels generator

    Science.gov (United States)

    Yang, Peidong; Chan, Candace; Sun, Jianwei; Liu, Bin

    2016-05-24

    This disclosure provides systems, methods, and apparatus related to a nanowire mesh solar fuels generator. In one aspect, a nanowire mesh solar fuels generator includes (1) a photoanode configured to perform water oxidation and (2) a photocathode configured to perform water reduction. The photocathode is in electrical contact with the photoanode. The photoanode may include a high surface area network of photoanode nanowires. The photocathode may include a high surface area network of photocathode nanowires. In some embodiments, the nanowire mesh solar fuels generator may include an ion conductive polymer infiltrating the photoanode and the photocathode in the region where the photocathode is in electrical contact with the photoanode.

  14. The Mechanical Properties of Nanowires

    Science.gov (United States)

    Wang, Shiliang; Shan, Zhiwei

    2017-01-01

    Applications of nanowires into future generation nanodevices require a complete understanding of the mechanical properties of the nanowires. A great research effort has been made in the past two decades to understand the deformation physics and mechanical behaviors of nanowires, and to interpret the discrepancies between experimental measurements and theoretical predictions. This review focused on the characterization and understanding of the mechanical properties of nanowires, including elasticity, plasticity, anelasticity and strength. As the results from the previous literature in this area appear inconsistent, a critical evaluation of the characterization techniques and methodologies were presented. In particular, the size effects of nanowires on the mechanical properties and their deformation mechanisms were discussed. PMID:28435775

  15. Selective formation of tungsten nanowires

    Directory of Open Access Journals (Sweden)

    Bien Daniel

    2011-01-01

    Full Text Available Abstract We report on a process for fabricating self-aligned tungsten (W nanowires with polycrystalline silicon core. Tungsten nanowires as thin as 10 nm were formed by utilizing polysilicon sidewall transfer technology followed by selective deposition of tungsten by chemical vapor deposition (CVD using WF6 as the precursor. With selective CVD, the process is self-limiting whereby the tungsten formation is confined to the polysilicon regions; hence, the nanowires are formed without the need for lithography or for additional processing. The fabricated tungsten nanowires were observed to be perfectly aligned, showing 100% selectivity to polysilicon and can be made to be electrically isolated from one another. The electrical conductivity of the nanowires was characterized to determine the effect of its physical dimensions. The conductivity for the tungsten nanowires were found to be 40% higher when compared to doped polysilicon nanowires of similar dimensions.

  16. Piezoresistive boron doped diamond nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Wang, Xinpeng

    2017-07-04

    A UNCD nanowire comprises a first end electrically coupled to a first contact pad which is disposed on a substrate. A second end is electrically coupled to a second contact pad also disposed on the substrate. The UNCD nanowire is doped with a dopant and disposed over the substrate. The UNCD nanowire is movable between a first configuration in which no force is exerted on the UNCD nanowire and a second configuration in which the UNCD nanowire bends about the first end and the second end in response to a force. The UNCD nanowire has a first resistance in the first configuration and a second resistance in the second configuration which is different from the first resistance. The UNCD nanowire is structured to have a gauge factor of at least about 70, for example, in the range of about 70 to about 1,800.

  17. On-chip surface modified nanostructured ZnO as functional pH sensors

    Science.gov (United States)

    Zhang, Qing; Liu, Wenpeng; Sun, Chongling; Zhang, Hao; Pang, Wei; Zhang, Daihua; Duan, Xuexin

    2015-09-01

    Zinc oxide (ZnO) nanostructures are promising candidates as electronic components for biological and chemical applications. In this study, ZnO ultra-fine nanowire (NW) and nanoflake (NF) hybrid structures have been prepared by Au-assisted chemical vapor deposition (CVD) under ambient pressure. Their surface morphology, lattice structures, and crystal orientation were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Two types of ZnO nanostructures were successfully integrated as gate electrodes in extended-gate field-effect transistors (EGFETs). Due to the amphoteric properties of ZnO, such devices function as pH sensors. We found that the ultra-fine NWs, which were more than 50 μm in length and less than 100 nm in diameter, performed better in the pH sensing process than NW-NF hybrid structures because of their higher surface-to-volume ratio, considering the Nernst equation and the Gouy-Chapman-Stern model. Furthermore, the surface coating of (3-Aminopropyl)triethoxysilane (APTES) protects ZnO nanostructures in both acidic and alkaline environments, thus enhancing the device stability and extending its pH sensing dynamic range.

  18. Shape-dependent plasma-catalytic activity of ZnO nanomaterials coated on porous ceramic membrane for oxidation of butane.

    Science.gov (United States)

    Sanjeeva Gandhi, M; Mok, Young Sun

    2014-12-01

    In order to explore the effects of the shape of ZnO nanomaterials on the plasma-catalytic decomposition of butane and the distribution of byproducts, three types of ZnO nanomaterials (nanoparticles (NPs), nanorods (NRs) and nanowires (NWs)) were prepared and coated on multi-channel porous alumina ceramic membrane. The structures and morphologies of the nanomaterials were confirmed by X-ray diffraction method and scanning electron microscopy. The observed catalytic activity of ZnO in the oxidative decomposition of butane was strongly shape-dependent. It was found that the ZnO NWs exhibited higher catalytic activity than the other nanomaterials and could completely oxidize butane into carbon oxides (COx). When using the bare or ZnO NPs-coated ceramic membrane, several unwanted partial oxidation and decomposition products like acetaldehyde, acetylene, methane and propane were identified during the decomposition of butane. When the ZnO NWs- or ZnO NRs-coated membrane was used, however, the formation of such unwanted byproducts except methane was completely avoided, and full conversion into COx was achieved. Better carbon balance and COx selectivity were obtained with the ZnO NWs and NRs than with the NPs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Catalyst-free fabrication of novel ZnO/CuO core-Shell nanowires heterojunction: Controlled growth, structural and optoelectronic properties

    Science.gov (United States)

    Khan, Muhammad Arif; Wahab, Yussof; Muhammad, Rosnita; Tahir, Muhammad; Sakrani, Samsudi

    2018-03-01

    Development of controlled growth and vertically aligned ZnO/CuO core-shell heterojunction nanowires (NWs) with large area by a catalyst free vapor deposition and oxidation approach has been investigated. Structural characterization reveals successful fabrication of a core ZnO nanowire having single crystalline hexagonal wurtzite structure along [002] direction and CuO nanostructure shell with thickness (8-10 nm) having polycrystalline monoclinic structure. The optical property analysis suggests that the reflectance spectrum of ZnO/CuO heterostructure nanowires is decreased by 18% in the visible range, which correspondingly shows high absorption in this region as compared to pristine ZnO nanowires. The current-voltage (I-V) characteristics of core-shell heterojunction nanowires measured by conductive atomic force microscopy (C-AFM) shows excellent rectifying behavior, which indicates the characteristics of a good p-n junction. The high-resolution transmission electron microscopy (HRTEM) has confirmed the sharp junction interface between the core-shell heterojunction nanowire arrays. The valence band offset and conduction band offset at ZnO/CuO heterointerfaces are measured to be 2.4 ± 0.05 and 0.23 ± 0.005 eV respectively, using X-ray photoelectron spectroscopy (XPS) and a type-II band alignment structure is found. The results of this study contribute to the development of new advanced device heterostructures for solar energy conversion and optoelectronics applications.

  20. Gigantic Enhancement in Sensitivity Using Schottky Contacted Nanowire Nanosensor

    KAUST Repository

    Wei, Te-Yu

    2009-12-09

    A new single nanowire based nanosensor is demonstrated for illustrating its ultrahigh sensitivity for gas sensing. The device is composed of a single ZnO nanowire mounted on Pt electrodes with one end in Ohmic contact and the other end in Schottky contact. The Schottky contact functions as a "gate" that controls the current flowing through the entire system. By tuning the Schottky barrier height through the responsive variation of the surface chemisorbed gases and the amplification role played by the nanowire to Schottky barrier effect, an ultrahigh sensitivity of 32 000% was achieved using the Schottky contacted device operated in reverse bias mode at 275 °C for detection of 400 ppm CO, which is 4 orders of magnitude higher than that obtained using an Ohmic contact device under the same conditions. In addition, the response time and reset time have been shortened by a factor of 7. The methodology and principle illustrated in the paper present a new sensing mechanism that can be readily and extensively applied to other gas sensing systems. © 2009 American Chemical Society.

  1. Single nanowire-based UV photodetectors for fast switching

    Science.gov (United States)

    Ul Hasan, Kamran; Alvi, N. H.; Lu, Jun; Nur, O.; Willander, Magnus

    2011-04-01

    Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage ( I- V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

  2. Aging of Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, Frank; Schiek, Manuela; Osadnik, Andreas

    2012-01-01

    conditions already expose substantial changes in sample morphology within hours. Clusters show Ostwald ripening, whereas nanowires reveal strong faceting and even fragmentation. All these aging effects are ascribed to the influence of water vapor. Decay curves (cluster number vs. time) for clusters...

  3. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

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

    2005-01-01

    This article is focused on the use of electrodeposition and of various nanoporous templates for the fabrication of metallic nanowires made from single metals (Ni, Co, Pb, Sn), alloys (NiFe, CoFe, CoPt), and multilayers (Co/Cu, NiFe/Cu). An overview is given of our recent studies performed on both...... discussed....

  4. Writing and functionalisation of suspended DNA nanowires on superhydrophobic pillar arrays

    KAUST Repository

    Miele, Ermanno

    2014-08-08

    Nanowire arrays and networks with precisely controlled patterns are very interesting for innovative device concepts in mesoscopic physics. In particular, DNA templates have proven to be versatile for the fabrication of complex structures that obtained functionality via combinations with other materials, for example by functionalisation with molecules or nanoparticles, or by coating with metals. Here, the controlled motion of the a three-phase contact line (TCL) of DNA-loaded drops on superhydrophobic substrates is used to fabricate suspended nanowire arrays. In particular, the deposition of DNA wires is imaged in situ, and different patterns are obtained on hexagonal pillar arrays by controlling the TCL velocity and direction. Robust conductive wires and networks are achieved by coating the wires with a thin layer of gold, and as proof of concept conductivity measurements are performed on single suspended wires. The plastic material of the superhydrophobic pillars ensures electrical isolation from the substrate. The more general versatility of these suspended nanowire networks as functional templates is outlined by fabricating hybrid organic-metal-semiconductor nanowires by growing ZnO nanocrystals onto the metal-coated nanowires.

  5. Ambient dependence of the phase of nanowires grown by annealing brass

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Himanshu; Ganguli, Tapas; Tiwari, Pragya; Srivastava, A. K.; Deb, S. K. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced technology, Indore-452013 (India)

    2012-06-05

    The growth of oxide nanowires has been studied by the annealing of brass (Cu 65%, Zn 35%) at different annealing temperatures and in different ambient. The annealing temperature was varied from 400 deg. C to 650 deg. C. Scanning Electron Microscope (SEM) results showed that the temperature has a significant effect on the density and size of the nanowires. The annealing temperature of 600 deg. C was found to be optimum for the growth of nanowires. The growth at 600 deg. C was observed in two ambient-air and moist nitrogen. Selected Area Electron Diffraction (SAED) and Energy Dispersive Spectroscopy (EDS) results on Transmission Electron Microscope (TEM) showed that with changing the ambient from air to moist nitrogen, the phase of the nanowires changed from Zn doped CuO to Cu doped ZnO. This result can be of significance importance as it suggests the use of ambient for the tuning of phase of oxide nanowires and in turn for the tuning of their physical properties.

  6. Writing and functionalisation of suspended DNA nanowires on superhydrophobic pillar arrays.

    Science.gov (United States)

    Miele, Ermanno; Accardo, Angelo; Falqui, Andrea; Marini, Monica; Giugni, Andrea; Leoncini, Marco; De Angelis, Francesco; Krahne, Roman; Di Fabrizio, Enzo

    2015-01-07

    Nanowire arrays and networks with precisely controlled patterns are very interesting for innovative device concepts in mesoscopic physics. In particular, DNA templates have proven to be versatile for the fabrication of complex structures that obtained functionality via combinations with other materials, for example by functionalisation with molecules or nanoparticles, or by coating with metals. Here, the controlled motion of the a three-phase contact line (TCL) of DNA-loaded drops on superhydrophobic substrates is used to fabricate suspended nanowire arrays. In particular, the deposition of DNA wires is imaged in situ, and different patterns are obtained on hexagonal pillar arrays by controlling the TCL velocity and direction. Robust conductive wires and networks are achieved by coating the wires with a thin layer of gold, and as proof of concept conductivity measurements are performed on single suspended wires. The plastic material of the superhydrophobic pillars ensures electrical isolation from the substrate. The more general versatility of these suspended nanowire networks as functional templates is outlined by fabricating hybrid organic-metal-semiconductor nanowires by growing ZnO nanocrystals onto the metal-coated nanowires. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Endface reflectivities of optical nanowires.

    Science.gov (United States)

    Wang, Shanshan; Hu, Zhifang; Yu, Huakang; Fang, Wei; Qiu, Min; Tong, Limin

    2009-06-22

    Endface reflectivities (ERs) of optical nanowires are investigated using three-dimensional finite-difference time-domain simulations. Typical ERs of both free-standing and substrate-supported silica, tellurite, PMMA and semiconductor nanowires or nanofibers are obtained. Unlike in conventional waveguides such as optical fibers, ERs of nanowires are usually considerably lower when operated in single mode. Dependences of ER on the diameter and the refractive index of the nanowire, and the wavelength of the guided light are also investigated. These results are helpful for estimating and understanding ERs in optical nanowires with diameters close to or smaller than the wavelengths of the light, and may offer valuable references for practical applications such as nanowire or nanofiber-based resonators and lasers.

  8. Optical Spectroscopy of Single Nanowires

    OpenAIRE

    Trägårdh, Johanna

    2008-01-01

    This thesis describes optical spectroscopy on III-V semiconductor nanowires. The nanowires were grown by metal-organic vapor phase epitaxy (MOVPE) and chemical beam epitaxy (CBE). Photoluminescence and photocurrent spectroscopy are used as tools to investigate issues such as the size of the band gap, the effects of surface states, and the charge carrier transport in core-shell nanowires. The band gap of InAs1-xPx nanowires with wurtzite crystal structure is measured as a function of ...

  9. ZnO Film Photocatalysts

    Directory of Open Access Journals (Sweden)

    Bosi Yin

    2014-01-01

    Full Text Available We have synthesized high-quality, nanoscale ultrathin ZnO films at relatively low temperature using a facile and effective hydrothermal approach. ZnO films were characterized by scanning electron microscope (SEM, X-ray diffraction (XRD, Raman spectroscopy, photoluminescence spectra (PL, and UV-vis absorption spectroscopy. The products demonstrated 95% photodegradation efficiency with Congo red (CR after 40 min irradiation. The photocatalytic degradation experiments of methyl orange (MO and eosin red also were carried out. The results indicate that the as-obtained ZnO films might be promising candidates as the excellent photocatalysts for elimination of waste water.

  10. Optical properties of ZnO-nanowire/CdSe-colloidal-quantum-dot hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dongchao; Richters, Jan-Peter; Dev, Apurba; Voss, Tobias [Semiconductor Optics, Institute of Solid State Physics, University of Bremen (Germany)

    2011-07-01

    One of the research interests in modern nanotechnology is the assembly and study of hybrid heterostructures composed of different materials that offer enhanced properties through the interactions between their different constituents. ZnO nanowires functionalized with colloidal semiconductor quantum dots (QDs) display tailored optical properties due to energy and electron transfer processes between these two components, and have a huge potential for applications in light-emitting and photovoltaic devices. Using a facile method, we synthesized water-soluble CdSe QDs with cadmium acetate and sodium selenosulfate as Cd and Se precursors, respectively. 3-mercaptopropionic acid (MPA) was used to cap the QDs, acting as the stabilizer, making the QDs water soluble and preventing them from agglomeration. TEM measurements demonstrated a narrow size distribution of the as-prepared QDs with the average diameter around 3 nm, consistent with UV-Vis absorption measurements. The carboxylic groups at the outer surface of the MPA-capped CdSe QDs render a tight and uniform attachment onto the surface of ZnO nanowires with high coverage efficiency possible. We studied the optical properties of the hybrid structures by photoluminescence spectroscopy under different temperatures to analyze the energy and electron transfer dynamics between the nanowires and the QDs.

  11. A scalable route to prepare core–shell structured ZnO@PEDOT nanowires and PEDOT nanotubes and their properties as electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fang, E-mail: 270220943@qq.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Xianhong, E-mail: zxh_0507@126.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Yang, Le, E-mail: 13613513412@126.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Xu, Dehong, E-mail: dedehenry@qq.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Ma, Yuhong, E-mail: mayh@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Dong, E-mail: chendong@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Wang, Li, E-mail: lwang@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhao, Changwen, E-mail: zhaocw@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Yang, Wantai, E-mail: yangwt@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2016-05-01

    Highlights: • ZnO@PEDOT nanowires and PEDOT nanotubes synthesized by chemical oxidation polymerization. • By controlling the ratio of ZnO/EDOT, ZnO@PEDOT formed different structures. • The maximum specific capacitance of PEDOT can reach 101.34 F/g. - Abstract: A composite of a core–shell structured nanowires with ZnO as a core and conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as a shell was prepared. At first, the hexagonal ZnO nanowires, with diameter of about 80–100 nm and length 4–5 μm, were fabricated by hydrothermal synthesis process. Then a thick layer of poly(trifluoroethyl methacrylate)-block-poly(sodium styrene sulfonate) (PTFEMA-b-PSSNa) was grafted from the surface of ZnO nanowires via atom transfer free radical polymerization. At last, with the ZnO@PTFEMA-b-PSSNa as a template and the PSSNa chain as the counterion dopant, PEDOT was precipitated onto the surface of the template to form the composite of ZnO@PEDOT/PSSNa. With the evaluation of the EDOT polymerization, the thickness of the PEDOT layer increased steadily. However, as the ratio of EDOT/ZnO was greater than 1:2, the ZnO nanowires templates were dissolved at last and then PEDOT particles were produced due to increasing of the acidity during the oxidation polymerization of EDOT. In this case, the product was the mixture of the nanotubes and particles of PEDOT/PPSNa. The electrochemical capacitances of the composites with different structures were investigated with cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy techniques with three-electrode cell configuration. The maximum specific capacitance of ZnO@PEDOT electrode can reach 101.34 F/g at 20 mV/s.

  12. Growth and characterization of ZnO/ZnTe core/shell nanowire arrays on transparent conducting oxide glass substrates

    Science.gov (United States)

    2012-01-01

    We report the growth and characterization of ZnO/ZnTe core/shell nanowire arrays on indium tin oxide. Coating of the ZnTe layer on well-aligned vertical ZnO nanowires has been demonstrated by scanning electron microscope, tunneling electron microscope, X-ray diffraction pattern, photoluminescence, and transmission studies. The ZnO/ZnTe core/shell nanowire arrays were then used as the active layer and carrier transport medium to fabricate a photovoltaic device. The enhanced photocurrent and faster response observed in ZnO/ZnTe, together with the quenching of the UV emission in the PL spectra, indicate that carrier separation in this structure plays an important role in determining their optical response. The results also indicate that core/shell structures can be made into useful photovoltaic devices. PMID:22804871

  13. Nanowire Field-Effect Transistors : Sensing Simplicity?

    NARCIS (Netherlands)

    Mescher, M.

    2014-01-01

    Silicon nanowires are structures made from silicon with at least one spatial dimension in the nanometer regime (1-100 nm). From these nanowires, silicon nanowire field-effect transistors can be constructed. Since their introduction in 2001 silicon nanowire field-effect transistors have been studied

  14. Effect of polyvinyl alcohol on electrochemically deposited ZnO thin films for DSSC applications

    Science.gov (United States)

    Marimuthu, T.; Anandhan, N.

    2017-05-01

    Nanostructures of zinc oxide (ZnO) thin film are electrochemically deposited in the absence and presence of polyvinyl alcohol (PVA) on fluorine doped tin oxide (FTO) substrate. X-ray diffraction (XRD) patterns and Raman spectroscopy confirmed the formation of hexagonal structure of ZnO. The film prepared in the presence of PVA showed a better crystallinity and its crystalline growth along the (002) plane orientation. Field emission scanning electron microscope (FE-SEM) images display nanowire arrays (NWAs) and sponge like morphology for films prepared in the absence and presence of PVA, respectively. Photoluminescence (PL) spectra depict the film prepared in the presence PVA having less atomic defects with good crystal quality compared with other film. Dye sensitized solar cell (DSSC) is constructed using low cost eosin yellow dye and current-voltage (J-V) curve is recorded for optimized sponge like morphology based solar cell.

  15. Effects of substrate annealing on the gold-catalyzed growth of ZnO nanostructures

    Directory of Open Access Journals (Sweden)

    Skåre Daniel

    2011-01-01

    Full Text Available Abstract The effects of thermal substrate pretreatment on the growth of Au-catalyzed ZnO nanostructures by pulsed laser deposition are investigated. C-plane sapphire substrates are annealed prior to deposition of a thin Au layer. Subsequent ZnO growths on substrates annealed above 1,200°C resulted in a high density of nanosheets and nanowires, whereas lower temperatures led to low nanostructure densities. Separate Au film annealing experiments at 700°C showed little variation in the size and density of the Au catalyst droplets with substrate annealing temperature. The observed variation in the density of nanostructures is attributed to the number of surface nucleation sites on the substrate, leading to a competition between nucleation promoted by the Au catalyst and surface nucleation sites on the rougher surfaces annealed below 1,200°C.

  16. Nanostructured ZnO films for potential use in LPG gas sensors

    Science.gov (United States)

    Latyshev, V. M.; Berestok, T. O.; Opanasyuk, A. S.; Kornyushchenko, A. S.; Perekrestov, V. I.

    2017-05-01

    The aim of the work was to obtain ZnO nanostructures with heightened surface area and to study relationship between formation method and gas sensor properties towards propane-butane mixture (LPG). In order to synthesize ZnO nanostructures chemical and physical formation methods have been utilized. The first one was chemical bath deposition technology and the second one magnetron sputtering of Zn followed by oxidation. Optimal method and technological parameters corresponding to formation of material with the highest sensor response have been determined experimentally. Dynamical gas sensor response at different temperature values and dependencies of the sensor sensitivity on the temperature at different LPG concentrations in air have been investigated. It has been found, that sensor response depends on the sample morphology and has the highest value for the structure consisting of thin nanowires. The factors that lead to the decrease in the gas sensor operating temperature have been determined.

  17. 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...

  18. Fabrication and characterization of flower-like CuO-ZnO heterostructure nanowire arrays by photochemical deposition.

    Science.gov (United States)

    Jung, Sungmook; Jeon, Seongho; Yong, Kijung

    2011-01-07

    A simple two step solution-based method was applied to fabricate CuO-ZnO heterostructured nanowire (NW) arrays. First, ZnO nanowires were grown on a Si substrate using the ammonia solution hydrothermal reaction. Afterwards, flower-like CuO crystals were photochemically deposited on the tip of the ZnO NWs, using ultraviolet (UV) light (312 nm wavelength) irradiation at room temperature. The morphology of the CuO was controlled by reaction time, density of ZnO NWs, and concentration of the solution. Because the deposited CuO is p-type and has narrow band gap properties, CuO-ZnO heterostructured NWs exhibited a stable p-n junction property and good ability to absorb visible light. Through investigation of UV light-triggered reaction phenomena, we found that the production of OH(-) from the photocatalytic process on the surface of ZnO NWs plays a critical role in the CuO deposition mechanism.

  19. Charge transfer modeling in monolayer circular graphene quantum dots-ZnO nanowires system for application in photovoltaic devices

    Science.gov (United States)

    Tamandani, Shahryar; Darvish, Ghafar

    2017-01-01

    We investigate electron transport between circular graphene quantum dots (CGQDs) and ZnO nanowires (ZnO NWs). This structure can be used as donor and acceptor in hybrid solar cells. We consider circular quantum dots (QDs) and use analytical calculation in order to estimate wavefunctions of GQD and ZnO NWs. After calculating the wavefunctions overlap, we use Marcus relation in order to calculate electron transfer rate. Also, we calculate this transfer rate for CdSe QDs-ZnO NWs system. Results from analytical calculation show that the transfer rate is limited to 1013 s-1. This result is in agreement with experimental results which are reported earlier. Such systems could be suitable for solar cells.

  20. Electrical Crystallization Mechanism and Interface Characteristics of Nanowire ZnO/Al Structures Fabricated by the Solution Method

    Directory of Open Access Journals (Sweden)

    Yi-Wei Tseng

    2012-01-01

    Full Text Available Both solution nanowire ZnO and sputtered Al thin film on SiO2 as the wire-film structure and the Al film were a conductive channel for electrical-induced crystallization (EIC. Direct current (DC raised the temperature of the Al film and improved the crystallization of the nanostructure. The effects of EIC not only induced Al atomic interface diffusion, but also doped Al on the roots of ZnO wires to form aluminum doped zinc oxide (AZO/ZnO wires. The Al doping concentration and the distance of the ZnO wire increased with increasing the electrical duration. Also, the electrical current-induced temperature was ~211°C (solid-state doped process and so could be applied to low-temperature optoelectronic devices.

  1. Electrical switching in Sb doped Al23Te77 glasses

    Science.gov (United States)

    Pumlianmunga; Ramesh, K.

    2017-08-01

    Bulk glasses (Al23Te77)Sbx (0≤ x≤10) prepared by melt quenching method show a change in switching type from threshold to memory for x≥5. An increase in threshold current (Ith) and a concomitant decrease in threshold voltage (Vth) and resisitivity(ρ) have been observed with the increase of Sb content. Raman spectra of the switched region in memory switching compositions show a red shift with respect to the as prepared glasses whereas in threshold switching compositions no such shift is observed. The magic angle spinning nuclear magnetic resonance (MAS NMR) of 27Al atom shows three different environments for Al ([4]Al, [5]Al and [6]Al). The samples annealed at their respective crystallization temperatures show rapid increase in [4]Al sites by annihilating [5]Al sites. The melts of threshold switching glasses (x≤2.5) quenched in water at room temperature (27 °C) show amorphous structure whereas, the melt of memory switching glasses (x>2.5) solidify into crystalline structure. The higher coordination of Al increases the cross-linking and rigidity. The addition of Sb increases the glass transition(Tg) and decreases the crystallization temperature(Tc). The decrease in the interval between the Tg and Tc eases the transition between the amorphous and crystalline states and improves the memory properties. The temperature rise at the time of switching can be as high as its melting temperature and the material in between the electrodes may melt to form a filament. The filament may consists of temporary (high resistive amorphous) and permanent (high conducting crystalline) units. The ratio between the temporary and the permanent units may decide the switching type. The filament is dominated by the permanent units in memory switching compositions and by the temporary units in threshold switching compositions. The present study suggests that both the threshold and memory switching can be understood by the thermal model and filament formation.

  2. Whispering gallery modes in zinc oxide micro- and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Czekalla, Christian; Nobis, Thomas; Rahm, Andreas; Cao, Bingqiang; Zuniga-Perez, Jesus; Sturm, Chris; Schmidt-Grund, Ruediger; Lorenz, Michael; Grundmann, Marius [Institut fuer Experimentelle Physik II, Fakultaet fuer Physik und Geowissenschaften, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany)

    2010-06-15

    Optical whispering gallery mode (WGM) resonances have been observed in zinc oxide micro- and nanowire cavities. Using model calculations, the experimentally observed mode spectrum was reproduced. The effect has been observed for wire radii between 100 nm and 10 {mu}m corresponding to angular mode numbers from 1 to about 250. The whispering gallery effect was used to determine the refractive index of the wires as a function of the photon energy and temperature. Under high excitation conditions, WGM lasing was observed. Two methods for calculating the complex resonant modes are presented: a simple plane wave model and the numerical solution of the Helmholtz equation for the given resonator geometry. A typical photoluminescence (PL) spectrum showing WGM resonances and (inset) a scanning electron microscopy (SEM) image of a zinc oxide (ZnO) microwire. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  3. GaN Nanowire Arrays for High-Output Nanogenerators

    KAUST Repository

    Huang, Chi-Te

    2010-04-07

    Three-fold symmetrically distributed GaN nanowire (NW) arrays have been epitaxially grown on GaN/sapphire substrates. The GaN NW possesses a triangular cross section enclosed by (0001), (2112), and (2112) planes, and the angle between the GaN NW and the substrate surface is ∼62°. The GaN NW arrays produce negative output voltage pulses when scanned by a conductive atomic force microscope in contact mode. The average of piezoelectric output voltage was about -20 mV, while 5-10% of the NWs had piezoelectric output voltages exceeding -(0.15-0.35) V. The GaN NW arrays are highly stable and highly tolerate to moisture in the atmosphere. The GaN NW arrays demonstrate an outstanding potential to be utilized for piezoelectric energy generation with a performance probably better than that of ZnO NWs. © 2010 American Chemical Society.

  4. ZnO UV Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radiation-hard UV detectors will be developed with ZnO in Phase I efforts by MOXtronics, Inc. (MOX). ZnO is a very suitable material for fabrication of high-speed,...

  5. Growth and electronic properties of GaN/ZnO solid solution nanowires

    Science.gov (United States)

    Han, Wei-Qiang; Zhang, Yan; Nam, Chang-Yong; Black, C. T.; Mendez, E. E.

    2010-08-01

    We have grown single-crystal (Ga1-xZnx)(N1-xOx) solid-solution nanowires using nanostructured ZnGa2O4 precursor prepared by a sol-gel method. From electrical transport measurements in individual nanowire field-effect transistors, we have identified the conduction as n-type and obtained a background carrier density (˜1019 cm-3) and an electron mobility (˜1 cm2/V s) that are consistent with chemical disorder and a large number of charge traps, as confirmed by the devices' photocurrent response. From the dependence of the device photoresponse on incident light wavelength, we have determined the energy band gap of (Ga0.88Zn0.12)(N0.88O0.12) to be as much as ˜0.6 eV lower than that of GaN or ZnO.

  6. Enhanced Cu₂S/CdS coaxial nanowire solar cells by piezo-phototronic effect.

    Science.gov (United States)

    Pan, Caofeng; Niu, Simiao; Ding, Yong; Dong, Lin; Yu, Ruomeng; Liu, Ying; Zhu, Guang; Wang, Zhong Lin

    2012-06-13

    Nanowire solar cells are promising candidates for powering nanosystems and flexible electronics. The strain in the nanowires, introduced during growth, device fabrication and/or application, is an important issue for piezoelectric semiconductor (like CdS, ZnO, and CdTe) based photovoltaic. In this work, we demonstrate the first largely enhanced performance of n-CdS/p-Cu(2)S coaxial nanowire photovoltaic (PV) devices using the piezo-phototronics effect when the PV device is subjected to an external strain. Piezo-phototronics effect could control the electron-hole pair generation, transport, separation, and/or recombination, thus enhanced the performance of the PV devices by as high as 70%. This effect offers a new concept for improving solar energy conversation efficiency by designing the orientation of the nanowires and the strain to be purposely introduced in the packaging of the solar cells. This study shed light on the enhanced flexible solar cells for applications in self-powered technology, environmental monitoring, and even defensive technology.

  7. Aqueous Phase Synthesis and Enhanced Field Emission Properties of ZnO-Sulfide Heterojunction Nanowires

    OpenAIRE

    Guojing Wang; Zhengcao Li; Mingyang Li; Chienhua Chen; Shasha Lv; Jiecui Liao

    2016-01-01

    ZnO-CdS, ZnO-ZnS, and ZnO-Ag2S core-shell heterojunction structures were fabricated using low-temperature, facile and simple aqueous solution approaches. The polycrystalline sulfide shells effectively enhance the field emission (FE) properties of ZnO nanowires arrays (NWAs). This results from the formation of the staggered gap heterointerface (ZnO-sulfide) which could lead to an energy well at the interfaces. Hence, electrons can be collected when an electric field is applied. It is observed ...

  8. Compact hybrid cell based on a convoluted nanowire structure for harvesting solar and mechanical energy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen; Wang, Zhong Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2011-02-15

    A fully integrated, solid-state, compact hybrid cell (CHC) that comprises ''convoluted'' ZnO nanowire structures for concurrent harvesting of both solar and mechanical energy is demonstrated. The compact hybrid cell is based on a conjunction design of an organic solid-state dye-sensitized solar cell (DSSC) and piezoelectric nanogenerator in one compact structure. The CHC shows a significant increase in output power, clearly demonstrating its potential for simultaneously harvesting multiple types of energy for powering small electronic devices for independent, sustainable, and mobile operation. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Superconductivity in nanowires

    CERN Document Server

    Bezryadin, Alexey

    2012-01-01

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

  10. Radiation Stability of Metal Nanowires

    Science.gov (United States)

    Bedin, S. A.; Makhin'ko, F. F.; Ovchinnikov, V. V.; Gerasimenko, N. N.; Zagorskiy, D. L.

    2017-01-01

    The aim of this work is to investigate the radiation stability of pure nickel and iron- nickel Fe0.56Ni0.44 alloy nanowires fabricated by matrix synthesis using polymer track membranes and Ar+ and Xe+ (E = 20 keV, j = 300 μA/cm2) beam irradiation. The dependence of the stability of nanowires on their diameter, fluence, and type of implanted ions is investigated. The assumption that the thermalized regions of dense cascades of atomic displacements (thermal spikes) play an important role in the nanowire structure change is made. These regions are nanosized zones of explosive energy release and heated to several thousands of degrees.

  11. Fabrication of a P3HT-ZnO Nanowires Gas Sensor Detecting Ammonia Gas

    Directory of Open Access Journals (Sweden)

    Chin-Guo Kuo

    2017-12-01

    Full Text Available In this study, an organic-inorganic semiconductor gas sensor was fabricated to detect ammonia gas. An inorganic semiconductor was a zinc oxide (ZnO nanowire array produced by atomic layer deposition (ALD while an organic material was a p-type semiconductor, poly(3-hexylthiophene (P3HT. P3HT was suitable for the gas sensing application due to its high hole mobility, good stability, and good electrical conductivity. In this work, P3HT was coated on the zinc oxide nanowires by the spin coating to form an organic-inorganic heterogeneous interface of the gas sensor for detecting ammonia gas. The thicknesses of the P3HT were around 462 nm, 397 nm, and 277 nm when the speeds of the spin coating were 4000 rpm, 5000 rpm, and 6000 rpm, respectively. The electrical properties and sensing characteristics of the gas sensing device at room temperature were evaluated by Hall effect measurement and the sensitivity of detecting ammonia gas. The results of Hall effect measurement for the P3HT-ZnO nanowires semiconductor with 462 nm P3HT film showed that the carrier concentration and the mobility were 2.7 × 1019 cm−3 and 24.7 cm2∙V−1∙s−1 respectively. The gas sensing device prepared by the P3HT-ZnO nanowires semiconductor had better sensitivity than the device composed of the ZnO film and P3HT film. Additionally, this gas sensing device could reach a maximum sensitivity around 11.58 per ppm.

  12. Sensing performances of pure and hybridized carbon nanotubes-ZnO nanowire networks: A detailed study.

    Science.gov (United States)

    Lupan, Oleg; Schütt, Fabian; Postica, Vasile; Smazna, Daria; Mishra, Yogendra Kumar; Adelung, Rainer

    2017-11-07

    In this work, the influence of carbon nanotube (CNT) hybridization on ultraviolet (UV) and gas sensing properties of individual and networked ZnO nanowires (NWs) is investigated in detail. The CNT concentration was varied to achieve optimal conditions for the hybrid with improved sensing properties. In case of CNT decorated ZnO nanonetworks, the influence of relative humidity (RH) and applied bias voltage on the UV sensing properties was thoroughly studied. By rising the CNT content to about 2.0 wt% (with respect to the entire ZnO network) the UV sensing response is considerably increased from 150 to 7300 (about 50 times). With respect to gas sensing, the ZnO-CNT networks demonstrate an excellent selectivity as well as a high gas response to NH3 vapor. A response of 430 to 50 ppm at room temperature was obtained, with an estimated detection limit of about 0.4 ppm. Based on those results, several devices consisting of individual ZnO NWs covered with CNTs were fabricated using a FIB/SEM system. The highest sensing performance was obtained for the finest NW with diameter (D) of 100 nm,  with a response of about 4 to 10 ppm NH3 vapor at room temperature.

  13. Zinc-oxide nanowires electrochemically grown onto sol-gel spin-coated seed layers

    Energy Technology Data Exchange (ETDEWEB)

    Bojorge, Claudia D.; Canepa, Horacio R. [CINSO, CONICET-CITEDEF, Juan B. de La Salle 4397, CP 1603 Villa Martelli, Buenos Aires (Argentina); Kent, Vladimir R.; Teliz, Erika; Marotti, Ricardo E.; Dalchiele, Enrique A. [Facultad de Ingenieria, Instituto de Fisica, Universidad de la Republica, J. H. Reissig 565, CC 30, CP 11000, Montevideo (Uruguay); Henriquez, Rodrigo; Gomez, Humberto [Facultad de Ciencias, Instituto de Quimica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile)

    2011-07-15

    The electrochemical deposition of ZnO nanowires (NW) was optimized by growing onto a previously deposited seed layer. The ZnO seed layer was prepared by a sol-gel process from different precursor solutions and deposited onto FTO/glass by spin coating. Afterwards, NW were electrochemically grown onto those seed layers. The electrolyte was an aqueous solution of the Zn{sup +2} precursor (1 mM zinc acetate) and a supporting electrolyte (0.1 M sodium acetate), saturated with bubbling oxygen. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical transmittance. The XRD measurements show typical diffraction pattern of ZnO wurtzite structure. The SEM micrographs show the presence of smooth NW with hexagonal sections with diameters ranging from 40 to 250 nm. The optical transmittance reveals the presence of ZnO with bandgap energy between 3.23 and 3.29 eV. These spectra show a monotonically increasing transmittance from the UV into the red part of the spectrum. This feature may be originated in the dispersion of light at the NW and can be used to enhance below-gap absorption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Semiconductor nanowires and nanowire heterostructures: Nanoscience from the bottom up

    Science.gov (United States)

    Zhong, Zhaohui

    2005-07-01

    Nanoscale science and technology involves interdisciplinary research at the interface of chemistry, physics, biology, and engineering sciences. By developing and following a unique intellectual path---the bottom-up paradigm of nanoscale science and technology---it is possible to assemble integrated nanoscale systems with novel functionalities beyond the conventional lithography limit. In this thesis, I present research efforts focused on fundamental aspects of this bottom-up paradigm using semiconductor nanowires (NWs) and nanowire heterostructures as nanoscale building blocks. We first present studies conducted on one of the most important semiconductor materials, silicon nanowires (SiNWs). SiNWs are rationally synthesized via a metal cluster-catalyzed vapor-liquid-solid (VLS) growth mechanism. Room temperature electrical transport studies carried out on SiNW field effect transistors (FETs) show exceptional device performance; estimated hole mobilities in p-SiNWs are significantly higher than bulk silicon at similar doping levels. Furthermore, low temperature transport studies on molecular scale SiNWs reveal phase coherent single charge transport through discrete single particle quantum levels with length scales up to several hundred nanometers. Finally, we show that SiNWs can be assembled into functional nanoelectronic devices. We then discuss two types of nanowire heterostructures: modulation doped silicon nanowires, and branched and hyper-branched nanowire structures. All key properties of modulation doped nanowires can be controlled during the synthesis, including the number, size and periodicity of the differentially doped regions. Their potential applications are also discussed. Moreover, branched and hyper-branched nanowire structures are synthesized via a multi-step nanocluster-catalyzed VLS approach, with branch density controlled by the nanocluster catalyst concentration. Lastly, we describe the realization of complementary doping in gallium nitride

  15. Interactions between semiconductor nanowires and living cells.

    Science.gov (United States)

    Prinz, Christelle N

    2015-06-17

    Semiconductor nanowires are increasingly used for biological applications and their small dimensions make them a promising tool for sensing and manipulating cells with minimal perturbation. In order to interface cells with nanowires in a controlled fashion, it is essential to understand the interactions between nanowires and living cells. The present paper reviews current progress in the understanding of these interactions, with knowledge gathered from studies where living cells were interfaced with vertical nanowire arrays. The effect of nanowires on cells is reported in terms of viability, cell-nanowire interface morphology, cell behavior, changes in gene expression as well as cellular stress markers. Unexplored issues and unanswered questions are discussed.

  16. Simulation, optimization and testing of a novel high spatial resolution X-ray imager based on Zinc Oxide nanowires in Anodic Aluminium Oxide membrane using Geant4

    Science.gov (United States)

    Esfandi, F.; Saramad, S.

    2015-07-01

    In this work, a new generation of scintillator based X-ray imagers based on ZnO nanowires in Anodized Aluminum Oxide (AAO) nanoporous template is characterized. The optical response of ordered ZnO nanowire arrays in porous AAO template under low energy X-ray illumination is simulated by the Geant4 Monte Carlo code and compared with experimental results. The results show that for 10 keV X-ray photons, by considering the light guiding properties of zinc oxide inside the AAO template and suitable selection of detector thickness and pore diameter, the spatial resolution less than one micrometer and the detector detection efficiency of 66% are accessible. This novel nano scintillator detector can have many advantages for medical applications in the future.

  17. New insights in the structural and morphological properties of sol-gel deposited ZnO multilayer films

    Science.gov (United States)

    Demes, T.; Ternon, C.; Riassetto, D.; Roussel, H.; Rapenne, L.; Gélard, I.; Jimenez, C.; Stambouli, V.; Langlet, M.

    2016-08-01

    This study shows how the structural and morphological properties of sol-gel deposited ZnO films can be precisely tuned and selectively controlled. For that purpose, ZnO films have been deposited through a multilayer sol-gel route using solutions of zinc acetate dihydrate (ZAD) diluted in 1-butanol. The opto-geometrical, morphological, and structural properties of these films have been thoroughly studied in relation to the ZAD concentration in butanol, number of deposited single-layers, and heat-treatment conditions. On this basis, different physical processes occurring over the multilayer deposition procedure have been discussed to explain how the experimental parameters influence the film properties and enable to tune the grain size, texture coefficient, and surface coverage rate in a wide range of values. This work is a first step toward the optimized growth of ZnO nanowires on sol-gel films and their subsequent integration in 2D or 3D nanowire-based biosensors.

  18. Vibration of Piezoelectric ZnO-SWCNT Nanowires

    Directory of Open Access Journals (Sweden)

    Yao Xiao

    2016-12-01

    Full Text Available A hybrid nanowire (HNW was constructed by coating a single-wall carbon nanotube (SWCNT with piezoelectric zinc oxide (ZnO. The two components of the HNW interact with each other via the van der Waals (vdW force. This paper aims to study the effect of the piezoelectricity in the ZnO layer and the inter-phase vdW interaction on the fundamental vibration of the HNWs. In doing this, a new model was developed where the two components of the HNWs were modeled as Euler beams coupled via the interphase vdW interaction. Based on the model, the dependence of the frequency on an applied electrical voltage was calculated for HNWs of different geometric sizes to reveal the voltage effect. The results were then compared with those calculated without considering the inter-phase vdW interaction. It was found that the interphase vdW interaction can substantially decrease the structural stiffness, leading to a greatly enhanced piezoelectric effect but a lower frequency for the vibration of the HNWs.

  19. Phosphorus Doped Zn 1- x Mg x O Nanowire Arrays

    KAUST Repository

    Lin, S. S.

    2009-11-11

    We demonstrate the growth of phosphorus doped Zn 1-xMg xO nanowire (NW) using pulsed laser deposition. For the first time, p-type Zn 0.92Mg 0.08O:P NWs are likely obtained In reference to atomic force microscopy based piezoelectric output measurements, X-ray photoelectron spectroscopy, and the transport property between the NWs and a n-type ZnO film. A shallow acceptor level of ∼140 meV Is identified by temperaturedependent photoluminescence. A piezoelectric output of 60 mV on average has been received using the doped NWs. Besides a control on NW aspect ratio and density, band gap engineering has also been achieved by alloying with Mg to a content of x = 0.23. The alloyed NWs with controllable conductivity type have potential application In high-efficiency all-ZnO NWs based LED, high-output ZnO nanogenerator, and other optical or electrical devices. © 2009 American Chemical Society.

  20. Pengaruh Temperatur, Massa Zink, Substrat Dan Waktu Tahan Terhadap Struktur Dan Morfologi Zno Hasil Sintesis Dengan Metode Chemical Vapour Transport (CVT

    Directory of Open Access Journals (Sweden)

    Arisela Distyawan

    2013-09-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 Material Zink Oksida (ZnO telah berhasil disintesis menggunakan metode Chemical Vapour Transport dengan bahan dasar prekursor berupa serbuk Zn yang dipanaskan hingga mencapai temperatur uap dalam furnace horisontal. Adapun variasi yang diberikan dalam penelitian adalah berupa temperatur pemanasan (850, 900, dan 950oC, massa prekursor Zn (0,15, 0,25, dan 0,35g, lama waktu sputtering substrat (90 dan 180 detik, dan waktu tahan khusus untuk mengetahui initial growth ZnO (10, 20, 30, 40, 50, dan 60 menit. Pembentukan Zink Oksida (ZnO dikonfirmasi melalui data X-RD, dimana telah terbentuk material ZnO dengan struktur hexagonal wurtzite. Berdarsarkan data XRD juga diketahui ukuran kristal pada sampel sputtering 90 detik mengalami penurunan bersamaan penambahan massa Zn. Dari hasil pengamatan SEM didapatkan bahwa morfologi permukaan lapisan tipis ZnO terdiri dari berbagai macam bentuk berupa nanoparticle, nanowires, nanorods, dan nanotetrapod. Lapisan Zno paling tebal sebesar ±350 nm pada sampel 950oC-0,15g sputter 90 detik. Semakin tinggi temperatur operasi berdampak peningkatan ukuran partikel. Pengujian FTIR turut menguatkan terbentuknya lapisan tipis di permukaan substrat Alumina. Hal ini didasarkan terjadinya penyerapan vibrasi yang membentuk lekukan pada kisaran area 509 cm-1 dari masing-masing sampel.

  1. Visible to near-infrared light harvesting in Ag2S nanoparticles/ZnO nanowire array photoanodes.

    Science.gov (United States)

    Wu, Jih-Jen; Chang, Ru-Chun; Chen, Dian-Wei; Wu, Chun-Te

    2012-02-21

    Pronounced absorption in the visible-NIR range of 400-1300 nm is demonstrated in the Ag(2)S nanoparticles (NPs)/ZnO nanowire (NW) array. ZnO NW arrays are grown on indium tin oxide substrates using chemical bath deposition. The Ag(2)S NPs are sequentially formed on the ZnO NWs through sonochemical synthesis. Structural characterizations indicate the slight deconstruction of surface of ZnO NWs during Ag(2)S NPs formation. By employing polysulfide electrolyte, short-circuit current (J(sc)), open-circuit voltage and therefore the efficiency of the Ag(2)S NP-sensitized ZnO NW solar cell are improved with increasing the initial sulfur concentration in the sulfur-polysulfide electrolyte. The Ag(2)S NP-sensitized ZnO NW solar cell shows a conversion efficiency of 0.49% with a superior J(sc) of ~13.7 mA cm(-2) under AM 1.5 illumination at 100 mW cm(-2). Incident photon conversion efficiency measurements reveal that Ag(2)S NPs contribute to 33.4% and 65.2% of J(sc) in the wavelength ranges of 400-700 nm and 700-1300 nm, respectively. This journal is © The Royal Society of Chemistry 2012

  2. Surface Passivation of Germanium Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Adhikari, Hemant; Sun, Shiyu; Pianetta, Piero; Chidsey, Chirstopher E.D.; McIntyre, Paul C.; /SLAC, SSRL

    2005-05-13

    The surface of single crystal, cold-wall CVD-grown germanium nanowires was studied by synchrotron radiation photoemission spectroscopy (SR-PES) and also by conventional XPS. The as-grown germanium nanowires seem to be hydrogen terminated. Exposure to laboratory atmosphere leads to germanium oxide growth with oxidation states of Ge{sup 1+}, Ge{sup 2+}, Ge{sup 3+}, while exposure to UV light leads to a predominance of the Ge{sup 4+} oxidation state. Most of the surface oxide could be removed readily by aqueous HF treatment which putatively leaves the nanowire surface hydrogen terminated with limited stability in air. Alternatively, chlorine termination could be achieved by aq. HCl treatment of the native oxide-coated nanowires. Chlorine termination was found to be relatively more stable than the HF-last hydrogen termination.

  3. Ballistic superconductivity in semiconductor nanowires

    NARCIS (Netherlands)

    Zhang, H.; Gül, Ö.; Conesa-Boj, S.; Nowak, M.P.; Wimmer, M.; Zuo, K.; Mourik, V.; Vries, F.K. de; Veen, J. van; Moor, M.W.A. de; Bommer, J.D.S.; Woerkom, D.J. van; Car, D.; Plissard, S.R.; Bakkers, E.P.A.M.; Quintero Pérez, M.; Cassidy, M.C.; Koelling, S.; Goswami, S.; Watanabe, K.; Taniguchi, T.; Kouwenhoven, L.P.

    2017-01-01

    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of

  4. A scalable route to prepare core-shell structured ZnO@PEDOT nanowires and PEDOT nanotubes and their properties as electrode materials

    Science.gov (United States)

    Wang, Fang; Zhang, Xianhong; Yang, Le; Xu, Dehong; Ma, Yuhong; Chen, Dong; Wang, Li; Zhao, Changwen; Yang, Wantai

    2016-05-01

    A composite of a core-shell structured nanowires with ZnO as a core and conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as a shell was prepared. At first, the hexagonal ZnO nanowires, with diameter of about 80-100 nm and length 4-5 μm, were fabricated by hydrothermal synthesis process. Then a thick layer of poly(trifluoroethyl methacrylate)-block-poly(sodium styrene sulfonate) (PTFEMA-b-PSSNa) was grafted from the surface of ZnO nanowires via atom transfer free radical polymerization. At last, with the ZnO@PTFEMA-b-PSSNa as a template and the PSSNa chain as the counterion dopant, PEDOT was precipitated onto the surface of the template to form the composite of ZnO@PEDOT/PSSNa. With the evaluation of the EDOT polymerization, the thickness of the PEDOT layer increased steadily. However, as the ratio of EDOT/ZnO was greater than 1:2, the ZnO nanowires templates were dissolved at last and then PEDOT particles were produced due to increasing of the acidity during the oxidation polymerization of EDOT. In this case, the product was the mixture of the nanotubes and particles of PEDOT/PPSNa. The electrochemical capacitances of the composites with different structures were investigated with cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques with three-electrode cell configuration. The maximum specific capacitance of ZnO@PEDOT electrode can reach 101.34 F/g at 20 mV/s.

  5. Continuous wet-process growth of ZnO nanoarrays for wire-shaped photoanode of dye-sensitized solar cell.

    Science.gov (United States)

    Tao, Pan; Guo, Wanwan; Du, Jun; Tao, Changyuan; Qing, Shenglan; Fan, Xing

    2016-09-15

    Well-aligned ZnO nanorod arrays have been grown on metal-plated polymer fiber via a mild wet process in a newly-designed continuous reactor, aiming to provide wire-shaped photoanodes for wearable dye-sensitized solar cells. The growth conditions were systematically optimized with the help of computational flow-field simulation. The flow field in the reactor will not only affect the morphology of the ZnO nanorod⧹nanowire but also affect the pattern distribution of nanoarray on the electrode surface. Unlike the sectional structure from the traditional batch-type reactor, ZnO nanorods with finely-controlled length and uniform morphology could be grown from the continuous reactor. After optimization, the wire-shaped ZnO-type photoanode grown from the continuous reactor exhibited better photovoltaic performance than that from the traditional batch-type reactor. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

    Directory of Open Access Journals (Sweden)

    Ki-Won Seo

    2015-12-01

    Full Text Available We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs. The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, the TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.

  7. Nonlinear optics in photonic nanowires.

    Science.gov (United States)

    Foster, Mark A; Turner, Amy C; Lipson, Michal; Gaeta, Alexander L

    2008-01-21

    We review recent research on nonlinear optical interactions in waveguides with sub-micron transverse dimensions, which are termed photonic nanowires. Such nanowaveguides, fabricated from glasses or semiconductors, provide the maximal confinement of light for index guiding structures enabling large enhancement of nonlinear interactions and group-velocity dispersion engineering. The combination of these two properties make photonic nanowires ideally suited for many nonlinear optical applications including the generation of single-cycle pulses and optical processing with sub-mW powers.

  8. Growth of vertically aligned ZnO nanorods using textured ZnO films

    OpenAIRE

    Meléndrez Manuel; Martínez Eduardo; Solís-Pomar Francisco; Pérez-Tijerina Eduardo

    2011-01-01

    Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the norm...

  9. Electrochemically grown rough-textured nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Pawan; Postetter, David; Saragnese, Daniel [Johns Hopkins University, Department of Chemical and Biomolecular Engineering (United States); Papadakis, Stergios J. [Johns Hopkins University, Applied Physics Laboratory (United States); Gracias, David H., E-mail: dgracias@jhu.ed [Johns Hopkins University, Department of Chemical and Biomolecular Engineering (United States)

    2010-03-15

    Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)-Au plating solution mixture that precipitates an Ag-Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices.

  10. Optical second harmonic generation from Pt nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, N.; Aratake, K.; Okushio, R.; Iwai, T. [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Sugawara, A. [Hitachi Advanced Research Laboratory, Akanuma 2520, Hatoyama, Saitama 350-0395 (Japan); Sano, H. [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Mizutani, G. [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)], E-mail: mizutani@jaist.ac.jp

    2007-09-15

    We have measured optical second harmonic intensity from arrays of Pt nanowires of 20 nm and 9 nm average widths, as a function of the incident and output light polarizations, the azimuthal angle, and the excitation photon energy. The nanowires were fabricated through shadow deposition on self-organized NaCl(1 1 0) faceted templates. The anisotropy of the SH intensity from the Pt nanowires was found to be stronger than that from the Au nanowires reported previously. The effective nonlinear susceptibility element {chi}{sub 222}{sup (2)}, with the suffix 2 indicating the direction [11-bar0], was observed for Pt nanowires, although it was not observed for Au nanowires. This difference is suggested to be due to the weaker suppression of the incident fundamental fields by the depolarization field in the Pt nanowires and the larger anisotropy in the nonlinearity of Pt nanowires due to the thinner widths.

  11. A silicon nanowire heater and thermometer

    Science.gov (United States)

    Zhao, Xingyan; Dan, Yaping

    2017-07-01

    In the thermal conductivity measurements of thermoelectric materials, heaters and thermometers made of the same semiconducting materials under test, forming a homogeneous system, will significantly simplify fabrication and integration. In this work, we demonstrate a high-performance heater and thermometer made of single silicon nanowires (SiNWs). The SiNWs are patterned out of a silicon-on-insulator wafer by CMOS-compatible fabrication processes. The electronic properties of the nanowires are characterized by four-probe and low temperature Hall effect measurements. The I-V curves of the nanowires are linear at small voltage bias. The temperature dependence of the nanowire resistance allows the nanowire to be used as a highly sensitive thermometer. At high voltage bias, the I-V curves of the nanowire become nonlinear due to the effect of Joule heating. The temperature of the nanowire heater can be accurately monitored by the nanowire itself as a thermometer.

  12. Structural and tunneling properties of Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2013-12-06

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green\\'s function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.

  13. The effect of nanowire length and diameter on the properties of transparent, conducting nanowire films

    Science.gov (United States)

    Bergin, Stephen M.; Chen, Yu-Hui; Rathmell, Aaron R.; Charbonneau, Patrick; Li, Zhi-Yuan; Wiley, Benjamin J.

    2012-03-01

    This article describes how the dimensions of nanowires affect the transmittance and sheet resistance of a random nanowire network. Silver nanowires with independently controlled lengths and diameters were synthesized with a gram-scale polyol synthesis by controlling the reaction temperature and time. Characterization of films composed of nanowires of different lengths but the same diameter enabled the quantification of the effect of length on the conductance and transmittance of silver nanowire films. Finite-difference time-domain calculations were used to determine the effect of nanowire diameter, overlap, and hole size on the transmittance of a nanowire network. For individual nanowires with diameters greater than 50 nm, increasing diameter increases the electrical conductance to optical extinction ratio, but the opposite is true for nanowires with diameters less than this size. Calculations and experimental data show that for a random network of nanowires, decreasing nanowire diameter increases the number density of nanowires at a given transmittance, leading to improved connectivity and conductivity at high transmittance (>90%). This information will facilitate the design of transparent, conducting nanowire films for flexible displays, organic light emitting diodes and thin-film solar cells.This article describes how the dimensions of nanowires affect the transmittance and sheet resistance of a random nanowire network. Silver nanowires with independently controlled lengths and diameters were synthesized with a gram-scale polyol synthesis by controlling the reaction temperature and time. Characterization of films composed of nanowires of different lengths but the same diameter enabled the quantification of the effect of length on the conductance and transmittance of silver nanowire films. Finite-difference time-domain calculations were used to determine the effect of nanowire diameter, overlap, and hole size on the transmittance of a nanowire network. For

  14. Single-crystal vanadium pentoxide nanowires.

    Science.gov (United States)

    Gao, Shaokang; Chen, Yuzhen; Luo, Haiyan; Jiang, Lilong; Ye, Binghuo; Wei, Mingdeng; Wei, Kemei

    2008-07-01

    Single-crystal V2O5 nanowires were successfully synthesized from the starting materials V6O13 powder and water. The experimental results indicate that high purity nanowires can be obtained using this simple synthetic route in absence of templates or catalysts. The diameter of the nanowires was found to be ca. 20 approximately 60 nm and the length up to several tens of micrometers, and the phases of nanowires were determined by XRD and TEM measurements.

  15. 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

  16. Tip-growth mode and base-growth mode of Au-catalyzed zinc oxide nanowires using chemical vapor deposition technique

    Science.gov (United States)

    Pung, Swee-Yong; Choy, Kwang-Leong; Hou, Xianghui

    2010-07-01

    Tip-growth and base-growth modes of Au-catalyzed zinc oxide nanowires (ZnO NWs) were synthesized on Au-film pre-deposited silicon substrates using Chemical Vapor Deposition (CVD) technique. The diameter of tip-growth Au-catalyzed ZnO NWs was proportional to the Au film thickness, whereas the areal density of these NWs was inversely proportional to the Au film thickness. It would be more appropriate to explain the growth of Au-catalyzed ZnO NWs by a combination of Vapor-Liquid-Solid and Vapor-Solid (VLS-VS) mechanisms instead of the conventional VLS mechanism, regardless of tip-growth or base-growth mode of Au-catalyzed ZnO NWs. The competition between the VLS and VS mechanism in the effectiveness of capturing the adsorbed Zn and O atoms would determine the final morphology of ZnO NWs. In addition, Au catalyst promoted the growth rate of NWs as compared to the self-catalyzed ZnO NWs.

  17. Nanowire resonant tunneling diodes

    Science.gov (United States)

    Björk, M. T.; Ohlsson, B. J.; Thelander, C.; Persson, A. I.; Deppert, K.; Wallenberg, L. R.; Samuelson, L.

    2002-12-01

    Semiconductor heterostructures and their implementation into electronic and photonic devices have had tremendous impact on science and technology. In the development of quantum nanoelectronics, one-dimensional (1D) heterostructure devices are receiving a lot of interest. We report here functional 1D resonant tunneling diodes obtained via bottom-up assembly of designed segments of different semiconductor materials in III/V nanowires. The emitter, collector, and the central quantum dot are made from InAs and the barrier material from InP. Ideal resonant tunneling behavior, with peak-to-valley ratios of up to 50:1 and current densities of 1 nA/μm2 was observed at low temperatures.

  18. ZnO-ZnGa2O4 core-shell nanowire array for stable photoelectrochemical water splitting

    Science.gov (United States)

    Zhong, Miao; Li, Yanbo; Yamada, Ichiro; Delaunay, Jean-Jacques

    2012-02-01

    A dense array of vertically aligned ZnO-ZnGa2O4 core-shell nanowires was synthesized on a large scale on an a-plane sapphire substrate by a simple two-step chemical vapor deposition method. The ZnO cores and ZnGa2O4 shells of the nanowires are of single crystal quality and have aligned crystallographic orientations as evidenced from XRD and TEM analyses. Mott-Schottky analysis and voltage onset from the photocurrent-voltage curve confirm an n-type semiconductor property, a flat-band potential of -0.4 V (versus NHE) and a carrier density of 7 × 1018 cm-3 for the ZnO-ZnGa2O4 core-shell nanowires. A stable and large photocurrent of 1.2 mA cm-2 was obtained with the ZnO-ZnGa2O4 core-shell nanowire array when used as a photoanode at an applied bias of +0.7 V (versus Ag/AgCl) under a 300 W xenon lamp illumination. Moreover, a low dark current of ZnGa2O4 nanowire array. These results suggest that the dense array of ZnO-ZnGa2O4 core-shell nanowires provides enhanced electronic properties and stable anti-photocorrosion ability and, therefore, is promising as a photoanode in photoelectrochemical water splitting.A dense array of vertically aligned ZnO-ZnGa2O4 core-shell nanowires was synthesized on a large scale on an a-plane sapphire substrate by a simple two-step chemical vapor deposition method. The ZnO cores and ZnGa2O4 shells of the nanowires are of single crystal quality and have aligned crystallographic orientations as evidenced from XRD and TEM analyses. Mott-Schottky analysis and voltage onset from the photocurrent-voltage curve confirm an n-type semiconductor property, a flat-band potential of -0.4 V (versus NHE) and a carrier density of 7 × 1018 cm-3 for the ZnO-ZnGa2O4 core-shell nanowires. A stable and large photocurrent of 1.2 mA cm-2 was obtained with the ZnO-ZnGa2O4 core-shell nanowire array when used as a photoanode at an applied bias of +0.7 V (versus Ag/AgCl) under a 300 W xenon lamp illumination. Moreover, a low dark current of ZnGa2O4 nanowire array

  19. Corrosion detection of nanowires by magnetic sensors

    KAUST Repository

    Kosel, Jürgen

    2017-10-05

    Disclosed are various embodiments related to a corrosion detection device for detecting corrosive environments. A corrosion detection device comprises a magnetic sensor and at least one magnetic nanowire disposed on the magnetic sensor. The magnetic sensor is configured to detect corrosion of the one or more magnetic nanowires based at least in part on a magnetic field of the one or more magnetic nanowires.

  20. Oxide p-n Heterojunction of Cu2O/ZnO Nanowires and Their Photovoltaic Performance

    Directory of Open Access Journals (Sweden)

    Seung Ki Baek

    2013-01-01

    Full Text Available Oxide p-n heterojunction devices consisting of p-Cu2O/n-ZnO nanowires were fabricated on ITO/glass substrates and their photovoltaic performances were investigated. The vertically arrayed ZnO nanowires were grown by metal organic chemical vapor deposition, which was followed by the electrodeposition of the p-type Cu2O layer. Prior to the fabrication of solar cells, the effect of bath pH on properties of the absorber layers was studied to determine the optimal condition of the Cu2O electrodeposition process. With the constant pH 11 solution, the Cu2O layer preferred the (111 orientation, which gave low electrical resistivity and high optical absorption. The Cu2O (pH 11/ZnO nanowire-based solar cell exhibited a higher conversion efficiency of 0.27% than the planar structure solar cell (0.13%, because of the effective charge collection in the long wavelength region and because of the enhanced junction area.