INVESTIGATION OF FLIP-FLOP PERFORMANCE ON DIFFERENT TYPE AND ARCHITECTURE IN SHIFT REGISTER WITH PARALLEL LOAD APPLICATIONS

Directory of Open Access Journals (Sweden)

Dwi Purnomo

2015-08-01

Full Text Available Register is one of the computer components that have a key role in computer organisation. Every computer contains millions of registers that are manifested by flip-flop. This research focuses on the investigation of flip-flop performance based on its type (D, T, S-R, and J-K and architecture (structural, behavioural, and hybrid. Each type of flip-flop on each architecture would be tested in different bit of shift register with parallel load applications. The experiment criteria that will be assessed are power consumption, resources required, memory required, latency, and efficiency. Based on the experiment, it could be shown that D flip-flop and hybrid architecture showed the best performance in required memory, latency, power consumption, and efficiency. In addition, the experiment results showed that the greater the register number, the less efficient the system would be.

Quantum transport in nanowire-based hybrid devices

Energy Technology Data Exchange (ETDEWEB)

Guenel, Haci Yusuf

2013-05-08

We have studied the low-temperature transport properties of nanowires contacted by a normal metal as well as by superconducting electrodes. As a consequence of quantum coherence, we have demonstrated the electron interference effect in different aspects. The mesoscopic phase coherent transport properties were studied by contacting the semiconductor InAs and InSb nanowires with normal metal electrodes. Moreover, we explored the interaction of the microscopic quantum coherence of the nanowires with the macroscopic quantum coherence of the superconductors. In superconducting Nb contacted InAs nanowire junctions, we have investigated the effect of temperature, magnetic field and electric field on the supercurrent. Owing to relatively high critical temperature of superconducting Nb (T{sub c} ∝ 9 K), we have observed the supercurrent up to 4 K for highly doped nanowire-based junctions, while for low doped nanowire-based junctions a full control of the supercurrent was achieved. Due to low transversal dimension of the nanowires, we have found a monotonous decay of the critical current in magnetic field dependent measurements. The experimental results were analyzed within narrow junction model which has been developed recently. At high bias voltages, we have observed subharmonic energy gap structures as a consequence of multiple Andreev reflection. Some of the nanowires were etched, such that the superconducting Nb electrodes are connected to both ends of the nanowire rather than covering the surface of the nanowire. As a result of well defined nanowire-superconductor interfaces, we have examined quasiparticle interference effect in magnetotransport measurements. Furthermore, we have developed a new junction geometry, such that one of the superconducting Nb electrodes is replaced by a superconducting Al. Owing to the smaller critical magnetic field of superconducting Al (B{sub c} ∝ 15-50,mT), compared to superconducting Nb (B{sub c} ∝ 3 T), we were able to studied

Patterning of self-assembled monolayers by phase-shifting mask and its applications in large-scale assembly of nanowires

Energy Technology Data Exchange (ETDEWEB)

Gao, Fan; Zhang, Dakuan; Wang, Jianyu; Sheng, Yun; Wang, Xinran; Chen, Kunji; Zhou, Minmin [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yan, Shancheng [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Shen, Jiancang; Pan, Lijia; Shi, Yi, E-mail: yshi@nju.edu.cn [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Micro-structures, Nanjing University, Nanjing 210093 (China)

2015-01-26

A nonselective micropatterning method of self-assembled monolayers (SAMs) based on laser and phase-shifting mask (PSM) is demonstrated. Laser beam is spatially modulated by a PSM, and periodic SAM patterns are generated sequentially through thermal desorption. Patterned wettability is achieved with alternating hydrophilic/hydrophobic stripes on octadecyltrichlorosilane monolayers. The substrate is then used to assemble CdS semiconductor nanowires (NWs) from a solution, obtaining well-aligned NWs in one step. Our results show valuably the application potential of this technique in engineering SAMs for integration of functional devices.

Growth and characterization of InGaAs based nanowire-heterostructures

International Nuclear Information System (INIS)

Treu, Julian Pascal

2017-01-01

tunability covering the technologically relevant telecommunication wavelengths. However, given their high surface-to-volume ratio, nanowire structures are especially prone to detrimental surface states, deteriorating in particular radiative efficiencies. Probing surfacestate related Fermi level pinning via detailed photoluminescence spectroscopy, we evaluate the influence of Ga-content on band bending and dominant recombination mechanism by studying as-grown nanowires covered by native oxide in comparison with nanowires free of oxide after wet-chemical treatment. In conjunction with complementary X-ray photoelectron spectroscopy, we identify a cross-over between surface electron accumulation for In-rich InGaAs nanowires to electron depletion for a gallium content between ∼ 20-30%. For stable passivation of deteriorating surface states higher bandgap materials are applied in radial core-shell geometry. Exploiting low surface recombination velocity and existing doping proficiency of InAsP, we establish a hybrid process combining MBE grown InAs core structures surrounded by metal organic vapor deposited (MOCVD) InAsP layers. This directly induces an increase in emission intensity by up to two orders of magnitude that can be related to high interface quality, as further corroborated by detailed TEM analysis of cross-sectional lamella structures. By systematically tuning thickness and phosphorus content we tune core-emission energies via strain-induced peak shifts and elucidate detrimental effects of plastic relaxation upon too high lattice mismatch. Introducing fully latticematched InGaAs-InAlAs heterostructures, such undesired strain accumulation and accompanied defect formation can be avoided, reflected by the absence of any strain-induced spectral shifts in peak emission energy and confirmed by high-resolution X-ray reciprocal space maps (strain ε core < 0.1%). As entirely in-situ based MBE process, exposure to ambient conditions is no longer required, further enhancing

Optical Sensing with Simultaneous Electrochemical Control in Metal Nanowire Arrays

Directory of Open Access Journals (Sweden)

Janos Vörös

2010-11-01

Full Text Available This work explores the alternative use of noble metal nanowire systems in large-scale array configurations to exploit both the nanowires’ conductive nature and localized surface plasmon resonance (LSPR. The first known nanowire-based system has been constructed, with which optical signals are influenced by the simultaneous application of electrochemical potentials. Optical characterization of nanowire arrays was performed by measuring the bulk refractive index sensitivity and the limit of detection. The formation of an electrical double layer was controlled in NaCl solutions to study the effect of local refractive index changes on the spectral response. Resonance peak shifts of over 4 nm, a bulk refractive index sensitivity up to 115 nm/RIU and a limit of detection as low as 4.5 × 10−4 RIU were obtained for gold nanowire arrays. Simulations with the Multiple Multipole Program (MMP confirm such bulk refractive index sensitivities. Initial experiments demonstrated successful optical biosensing using a novel form of particle-based nanowire arrays. In addition, the formation of an ionic layer (Stern-layer upon applying an electrochemical potential was also monitored by the shift of the plasmon resonance.

Charging effects and surface potential variations of Cu-based nanowires

Energy Technology Data Exchange (ETDEWEB)

Nunes, D., E-mail: daniela.gomes@fct.unl.pt [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Calmeiro, T.R.; Nandy, S.; Pinto, J.V.; Pimentel, A.; Barquinha, P. [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Carvalho, P.A. [SINTEF Materials and Chemistry, PB 124 Blindern, NO-0314, Oslo (Norway); CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisboa (Portugal); Walmsley, J.C. [SINTEF Materials and Chemistry, Materials and Nanotechnology, Høgskoleringen 5, 7034 Trondheim (Norway); Fortunato, E., E-mail: emf@fct.unl.pt [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Martins, R., E-mail: rm@uninova.pt [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal)

2016-02-29

The present work reports charging effects and surface potential variations in pure copper, cuprous oxide and cupric oxide nanowires observed by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). The copper nanowires were produced by wet synthesis, oxidation into cuprous oxide nanowires was achieved through microwave irradiation and cupric oxide nanowires were obtained via furnace annealing in atmospheric conditions. Structural characterization of the nanowires was carried out by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. During the EFM experiments the electrostatic field of the positive probe charged negatively the Cu-based nanowires, which in turn polarized the SiO{sub 2} dielectric substrate. Both the probe/nanowire capacitance as well as the substrate polarization increased with the applied bias. Cu{sub 2}O and CuO nanowires behaved distinctively during the EFM measurements in accordance with their band gap energies. The work functions (WF) of the Cu-based nanowires, obtained by KPFM measurements, yielded WF{sub CuO} > WF{sub Cu} > WF{sub Cu{sub 2O}}. - Highlights: • Charge distribution study in Cu, Cu{sub 2}O and CuO nanowires through electrostatic force microscopy • Structural/surface defect role on the charge distribution along the Cu nanowires • Determination of the nanowire work functions by Kelvin probe force microscopy • Three types of nanowires give a broad idea of charge behavior on Cu based-nanowires.

A Synoptic of Software Implementation for Shift Registers Based on 16th Degree Primitive Polynomials

Directory of Open Access Journals (Sweden)

Mirella Amelia Mioc

2016-08-01

Full Text Available Almost all of the major applications in the specific Fields of Communication used a well-known device called Linear Feedback Shift Register. Usually LFSR functions in a Galois Field GF(2n, meaning that all the operations are done with arithmetic modulo n degree Irreducible  and especially  Primitive Polynomials. Storing data in Galois Fields allows effective and manageable manipulation, mainly in computer cryptographic applications. The analysis of functioning for Primitive Polynomials of 16th degree shows that almost all the obtained results are in the same time distribution.

ZnO nanowire-based nano-floating gate memory with Pt nanocrystals embedded in Al2O3 gate oxides

International Nuclear Information System (INIS)

Yeom, Donghyuk; Kang, Jeongmin; Lee, Myoungwon; Jang, Jaewon; Yun, Junggwon; Jeong, Dong-Young; Yoon, Changjoon; Koo, Jamin; Kim, Sangsig

2008-01-01

The memory characteristics of ZnO nanowire-based nano-floating gate memory (NFGM) with Pt nanocrystals acting as the floating gate nodes were investigated in this work. Pt nanocrystals were embedded between Al 2 O 3 tunneling and control oxide layers deposited on ZnO nanowire channels. For a representative ZnO nanowire-based NFGM with embedded Pt nanocrystals, a threshold voltage shift of 3.8 V was observed in its drain current versus gate voltage (I DS -V GS ) measurements for a double sweep of the gate voltage, revealing that the deep effective potential wells built into the nanocrystals provide our NFGM with a large charge storage capacity. Details of the charge storage effect observed in this memory device are discussed in this paper

Development of a multistop TDC using a shift register for muon decay measurements in a pulsed beam

International Nuclear Information System (INIS)

Shimokoshi, F.; Kuno, Y.; Nagamine, K.; Yamazaki, T.; Tokyo Univ.

1990-01-01

New multistop CAMAC TDC modules using shift registers have been developed and were successfully used to measure the time spectrum of electrons from μ→eνanti ν decay in a high-intensity pulsed muon beam available at the UT-MSL/BOOM facility at KEK in Japan and after that also at Rutherford Appleton Laboratory. The time resolution of the TDC is as good as 16 ns. Among many features of the TDC, the combination of the shift register with fast memories is notable. By adopting this, the time range of the TDC can be extendable beyond the shift register depth without losing time resolution. The other feature is capability of making histograms in its own huge memories. The principle of operation and the performance of the TDC are described. (orig.)

High-temperature superconducting shift registers operating at up to 100 GHz

International Nuclear Information System (INIS)

Martens, J.S.; Pance, A.; Char, K.

1994-01-01

Shift registers have been demonstrated in YBaCuO operating at 77 K using from 64 to over 1,000 junctions. These are some of the larger scale integrated circuits demonstrated to date using YBaCuO Josephson technology. The circuit is a modified rapid single flux quantum design in which a single trigger pulse causes a one bit shift of the entire word of 32--512 b in length. Two different junction technologies, electron-beam defined nanobridges and epitaxial edge junctions, have been used with parameter spreads ranging from 11% to 22%. Correct operation has been verified with low speed random word tests and circulating data tests while pseudo random bit sequence demonstrations are underway. A practical amount of time to shift between cells has been measured to be about 10 ps

Excitonic terahertz photoconductivity in intrinsic semiconductor nanowires

Science.gov (United States)

Yan, Jie-Yun

2018-06-01

Excitonic terahertz photoconductivity in intrinsic semiconductor nanowires is studied. Based on the excitonic theory, the numerical method to calculate the photoconductivity spectrum in the nanowires is developed, which can simulate optical pump terahertz-probe spectroscopy measurements on real nanowires and thereby calculate the typical photoconductivity spectrum. With the help of the energetic structure deduced from the calculated linear absorption spectrum, the numerically observed shift of the resonant peak in the photoconductivity spectrum is found to result from the dominant exciton transition between excited or continuum states to the ground state, and the quantitative analysis is in good agreement with the quantum plasmon model. Besides, the dependence of the photoconductivity on the polarization of the terahertz field is also discussed. The numerical method and supporting theoretical analysis provide a new tool for experimentalists to understand the terahertz photoconductivity in intrinsic semiconductor nanowires at low temperatures or for nanowires subjected to below bandgap photoexcitation, where excitonic effects dominate.

40-Gbit/s all-optical circulating shift register with an inverter.

Science.gov (United States)

Hall, K L; Donnelly, J P; Groves, S H; Fennelly, C I; Bailey, R J; Napoleone, A

1997-10-01

We report what is believed to be the first demonstration of an all-optical circulating shift register using an ultrafast nonlinear interferometer with a polarization-insensitive semiconductor optical amplifier as the nonlinear switching element. The device operates at 40 Gbits/s, to our knowledge the highest speed demonstrated to date. Also, the demonstration proves the cascadability of the ultrafast nonlinear interferometric switch.

Controlling the exciton energy of a nanowire quantum dot by strain fields

Energy Technology Data Exchange (ETDEWEB)

Chen, Yan; Zhang, Jiaxiang; Ding, Fei, E-mail: f.ding@ifw-dresden.de [Institute for Integrative Nanosciences, IFW Dresden, Helmholtz Strasse 20, 01069 Dresden (Germany); Zadeh, Iman Esmaeil; Jöns, Klaus D.; Fognini, Andreas; Zwiller, Val [Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft (Netherlands); Reimer, Michael E. [Institute for Quantum Computing and Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, N2L 3G1 (Canada); Dalacu, Dan; Poole, Philip J. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada); Schmidt, Oliver G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtz Strasse 20, 01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer Strasse 70, 09107 Chemnitz (Germany)

2016-05-02

We present an experimental route to engineer the exciton energies of single quantum dots in nanowires. By integrating the nanowires onto a piezoelectric crystal, we controllably apply strain fields to the nanowire quantum dots. Consequently, the exciton energy of a single quantum dot in the nanowire is shifted by several meVs without degrading its optical intensity and single-photon purity. Second-order autocorrelation measurements are performed at different strain fields on the same nanowire quantum dot. The suppressed multi-photon events at zero time delay clearly verify that the quantum nature of single-photon emission is well preserved under external strain fields. The work presented here could facilitate on-chip optical quantum information processing with the nanowire based single photon emitters.

ZnO nanowire-based nano-floating gate memory with Pt nanocrystals embedded in Al{sub 2}O{sub 3} gate oxides

Energy Technology Data Exchange (ETDEWEB)

Yeom, Donghyuk; Kang, Jeongmin; Lee, Myoungwon; Jang, Jaewon; Yun, Junggwon; Jeong, Dong-Young; Yoon, Changjoon; Koo, Jamin; Kim, Sangsig [Department of Electrical Engineering and Institute for Nano Science, Korea University, Seoul 136-701 (Korea, Republic of)], E-mail: sangsig@korea.ac.kr

2008-10-01

The memory characteristics of ZnO nanowire-based nano-floating gate memory (NFGM) with Pt nanocrystals acting as the floating gate nodes were investigated in this work. Pt nanocrystals were embedded between Al{sub 2}O{sub 3} tunneling and control oxide layers deposited on ZnO nanowire channels. For a representative ZnO nanowire-based NFGM with embedded Pt nanocrystals, a threshold voltage shift of 3.8 V was observed in its drain current versus gate voltage (I{sub DS}-V{sub GS}) measurements for a double sweep of the gate voltage, revealing that the deep effective potential wells built into the nanocrystals provide our NFGM with a large charge storage capacity. Details of the charge storage effect observed in this memory device are discussed in this paper.

Silicon-on-Insulator Nanowire Based Optical Waveguide Biosensors

International Nuclear Information System (INIS)

Li, Mingyu; Liu, Yong; Chen, Yangqing; He, Jian-Jun

2016-01-01

Optical waveguide biosensors based on silicon-on-insulator (SOI) nanowire have been developed for label free molecular detection. This paper reviews our work on the design, fabrication and measurement of SOI nanowire based high-sensitivity biosensors employing Vernier effect. Biosensing experiments using cascaded double-ring sensor and Mach-Zehnder- ring sensor integrated with microfluidic channels are demonstrated (paper)

Moessbauer study of Fe-Co nanowires

Energy Technology Data Exchange (ETDEWEB)

Chen Ziyu [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou (China)]. E-mail: chenzy@lzu.edu.cn; Zhan Qingfeng; Xue Desheng; Li Fashen [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou (China); Zhou Xuezhi; Kunkel, Henry; Williams, Gwyn [Department of Physics and Astronomy, the University of Manitoba (Canada)

2002-01-28

Arrays of Fe{sub 1-x}Co{sub x} (0.0{<=}x{<=}0.92) nanowires have been prepared by an electrochemical process, co-depositing Fe and Co atoms into the pores of anodic aluminium; their compositions were determined by atomic absorption spectroscopy. Transmission electron microscope results show that the nanowires are regularly spaced and uniform in shape with lengths of about 7.5 {mu}m and diameters of 20 nm. The x-ray diffraction indicates a texture in the deposited nanowires. For the composition below 82 at.% cobalt, the nanowires had a body-centred-cubic structure with a [110] preferred orientation. For the 92 at.% cobalt sample, the alloy exhibited a mixture of bcc and face-centred-cubic structure. The room temperature {sup 57}Fe Moessbauer spectra of the arrays of Fe{sub 1-x}Co{sub x} nanowires have second and fifth absorption lines of the six-line pattern with almost zero intensity, indicating that the internal magnetic field in the nanowires lies along the long axis of the nanowire. The maximum values of the hyperfine field (B{sub hf} 36.6{+-}0.1 T) and isomer shift (IS=0.06{+-}0.01 mm s-1) occur for 44 at.% cobalt. The variations of the isomer shift and the linewidths with composition indicate that the Fe{sub 1-x}Co{sub x} alloy nanowires around the equiatomic composition are in an atomistic disordered state. (author)

Fast event recorder utilizing a CCD analog shift register

International Nuclear Information System (INIS)

Ducar, R.J.; McIntyre, P.M.

1978-01-01

A system of electronics has been developed to allow the capture and recording of relatively fast, low-amplitude analog events. The heart of the system is a dual 455-cell analog shift register charge-coupled device, Fairchild CCD321ADC-3. The CCD is operated in a dual clock mode. The input is sampled at a selectable clock rate of .25-20 MHz. The stored analog data is then clocked out at a slower rate, typically about .25 MHz. The time base expansion of the analog data allows for analog-to-digital conversion and memory storage using conventional medium-speed devices. The digital data is sequentially loaded into a static RAM and may then be block transferred to a computer. The analog electronics are housed in a single-width NIM module, and the RAM memory in a single-width CAMAC module. Each pair of modules provides six parallel channels. Cost is about $200.00 per channel. Applications are described for ionization imaging (TPC, IRC) and long-drift calorimetry in liquid argon

A ZnO nanowire-based photo-inverter with pulse-induced fast recovery.

Science.gov (United States)

Raza, Syed Raza Ali; Lee, Young Tack; Hosseini Shokouh, Seyed Hossein; Ha, Ryong; Choi, Heon-Jin; Im, Seongil

2013-11-21

We demonstrate a fast response photo-inverter comprised of one transparent gated ZnO nanowire field-effect transistor (FET) and one opaque FET respectively as the driver and load. Under ultraviolet (UV) light the transfer curve of the transparent gate FET shifts to the negative side and so does the voltage transfer curve (VTC) of the inverter. After termination of UV exposure the recovery of photo-induced current takes a long time in general. This persistent photoconductivity (PPC) is due to hole trapping on the surface of ZnO NWs. Here, we used a positive voltage short pulse after UV exposure, for the first time resolving the PPC issue in nanowire-based photo-detectors by accumulating electrons at the ZnO/dielectric interface. We found that a pulse duration as small as 200 ns was sufficient to reach a full recovery to the dark state from the UV induced state, realizing a fast UV detector with a voltage output.

Tuning electronic properties of In2O3 nanowires by doping control

International Nuclear Information System (INIS)

Lei, B.; Li, C.; Zhang, D.; Tang, D.; Zhou, C.

2004-01-01

We present two effective routes to tune the electronic properties of single-crystalline In 2 O 3 nanowires by controlling the doping. The first method involves using different O 2 concentrations during the synthesis. Lightly (heavily) doped nanowires were produced by using high (low) O 2 concentrations, respectively, as revealed by the conductances and threshold voltages of nanowire-based field-effect transistors. Our second method exploits post-synthesis baking, as baking heavily doped nanowires in ambient air led to suppressed conduction and a positive shift of the threshold voltage, whereas baking lightly doped nanowires in vacuum displayed the opposite behavior. Our approaches offer viable ways to tune the electronic properties of many nonstoichiometric metal oxide systems such as In 2 O 3 , SnO 2 , and ZnO nanowires for various applications

Electrical and Optical Characterization of Nanowire based Semiconductor Devices

Science.gov (United States)

Ayvazian, Talin

This research project is focused on a new strategy for the creation of nanowire based semiconductor devices. The main goal is to understand and optimize the electrical and optical properties of two types of nanoscale devices; in first type lithographically patterned nanowire electrodeposition (LPNE) method has been utilized to fabricate nanowire field effect transistors (NWFET) and second type involved the development of light emitting semiconductor nanowire arrays (NWLED). Field effect transistors (NWFETs) have been prepared from arrays of polycrystalline cadmium selenide (pc-CdSe) nanowires using a back gate configuration. pc-CdSe nanowires were fabricated using the lithographically patterned nanowire electrode- position (LPNE) process on SiO2 /Si substrates. After electrodeposition, pc-CdSe nanowires were thermally annealed at 300 °C x 4 h either with or without exposure to CdCl 2 in methanol a grain growth promoter. The influence of CdCl2 treatment was to increase the mean grain diameter as determined by X-ray diffraction pattern and to convert the crystal structure from cubic to wurtzite. Transfer characteristics showed an increase of the field effect mobility (mu eff) by an order of magnitude and increase of the Ion/I off ratio by a factor of 3-4. Light emitting devices (NW-LED) based on lithographically patterned pc-CdSe nanowire arrays have been investigated. Electroluminescence (EL) spectra of CdSe nanowires under various biases exhibited broad emission spectra centered at 750 nm close to the band gap of CdSe (1.7eV). To enhance the intensity of the emitted light and the external quantum efficiency (EQE), the distance between the contacts were reduced from 5 mum to less than 1 mum which increased the efficiency by an order of magnitude. Also, increasing the annealing temperature of nanowires from 300 °C x4 h to 450 This research project is focused on a new strategy for the creation of nanowire based semiconductor devices. The main goal is to understand

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.

ZnO nanowire-based glucose biosensors with different coupling agents

International Nuclear Information System (INIS)

Jung, Juneui; Lim, Sangwoo

2013-01-01

Highlights: ► Fabrication of ZnO nanowire-based glucose biosensors using different coupling agents. ► Highest sensitivity for (3-aminopropyl)methyldiethoxysilane-treated biosensor. ► 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 μA cm −2 mM −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.

Band bending at the heterointerface of GaAs/InAs core/shell nanowires monitored by synchrotron X-ray photoelectron spectroscopy

Science.gov (United States)

Khanbabaee, B.; Bussone, G.; Knutsson, J. V.; Geijselaers, I.; Pryor, C. E.; Rieger, T.; Demarina, N.; Grützmacher, D.; Lepsa, M. I.; Timm, R.; Pietsch, U.

2016-10-01

Unique electronic properties of semiconductor heterostructured nanowires make them useful for future nano-electronic devices. Here, we present a study of the band bending effect at the heterointerface of GaAs/InAs core/shell nanowires by means of synchrotron based X-ray photoelectron spectroscopy. Different Ga, In, and As core-levels of the nanowire constituents have been monitored prior to and after cleaning from native oxides. The cleaning process mainly affected the As-oxides and was accompanied by an energy shift of the core-level spectra towards lower binding energy, suggesting that the As-oxides turn the nanowire surfaces to n-type. After cleaning, both As and Ga core-levels revealed an energy shift of about -0.3 eV for core/shell compared to core reference nanowires. With respect to depth dependence and in agreement with calculated strain distribution and electron quantum confinement, the observed energy shift is interpreted by band bending of core-levels at the heterointerface between the GaAs nanowire core and the InAs shell.

Designing and building nanowires: directed nanocrystal self-assembly into radically branched and zigzag PbS nanowires

International Nuclear Information System (INIS)

Xu Fan; Ma Xin; Gerlein, L Felipe; Cloutier, Sylvain G

2011-01-01

Lead sulfide nanowires with controllable optoelectronic properties would be promising building blocks for various applications. Here, we report the hot colloidal synthesis of radically branched and zigzag nanowires through self-attachment of star-shaped and octahedral nanocrystals in the presence of multiple surfactants. We obtained high-quality single-crystal nanowires with uniform diameter along the entire length, and the size of the nanowire can be tuned by tailoring the reaction parameters. This slow oriented attachment provides a better understanding of the intricacies of this complex nanocrystal assembly process. Meanwhile, these self-assembled nanowire structures have appealing lateral conformations with narrow side arms or highly faceted edges, where strong quantum confinement can occur. Consequently, the single-crystal nanowire structures exhibit strong photoluminescence in the near-infrared region with a large blue-shift compared to the bulk material.

Scheduling and shift work characteristics associated with risk for occupational injury in newly licensed registered nurses: An observational study.

Science.gov (United States)

Stimpfel, Amy Witkoski; Brewer, Carol S; Kovner, Christine T

2015-11-01

Registered nurses across the globe bear a heavy injury burden. Every shift, nurses are exposed to a variety of hazards that can jeopardize their health, which negatively impacts their ability to provide high-quality patient care. Previous research suggests that inexperienced, or newly licensed nurses, may have an increased risk for certain occupational injuries. However, the current knowledge base is insufficient to fully understand how work hours influence newly licensed nurses' occupational injury, given the significant variation in hospital organization and work characteristics. To describe newly licensed nurses' shift work characteristics and determine the association between shift type and scheduling characteristics and nurse injury, before and after adjusting for individual and combined effects of demographics, external context, organizational context, and work context, following the Organization of Work model. This study is a secondary analysis of a nationally representative survey of newly licensed registered nurses using a cross-sectional design. The analytic sample includes 1744 newly licensed registered nurses from 34 states and the District of Columbia who reported working in a hospital and were within 6-18 months of passing their state licensure exam at the time of survey administration. Descriptive statistics were calculated, followed by bivariate and multivariate Poisson regression models to assess the relationship between shift type and scheduling characteristics and nurse injury. Lastly, full models with the addition of demographics, external context, organizational context, and work context variables were calculated. The majority (79%) of newly licensed nurses worked 12-h shifts, a near majority worked night shift (44%), and over half (61%) worked overtime (mandatory or voluntary) weekly. Nurses working weekly overtime were associated with a 32% [incidence rate ratio (IRR) 1.32, CI 1.07-1.62] increase in the risk of a needle stick and nurses

Modeling of surface stress effects on bending behavior of nanowires: Incremental deformation theory

International Nuclear Information System (INIS)

Song, F.; Huang, G.L.

2009-01-01

The surface stress effects on bending behavior of nanowires have recently attracted a lot of attention. In this letter, the incremental deformation theory is first applied to study the surface stress effects upon the bending behavior of the nanowires. Different from other linear continuum approaches, the local geometrical nonlinearity of the Lagrangian strain is considered, therefore, the contribution of the surface stresses is naturally derived by applying the Hamilton's principle, and influence of the surface stresses along all surfaces of the nanowires is captured. It is first shown that the surface stresses along all surfaces have contribution not only on the effective Young's modulus of the nanowires but also on the loading term in the governing equation. The predictions of the effective Young's modulus and the resonance shift of the nanowires from the current method are compared with those from the experimental measurement and other existing approaches. The difference with other models is discussed. Finally, based on the current theory, the resonant shift predictions by using both the modified Euler-Bernoulli beam and the modified Timoshenko beam theories of the nanowires are investigated and compared. It is noticed that the higher vibration modes are less sensitive to the surface stresses than the lower vibration modes.

Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

Directory of Open Access Journals (Sweden)

Ping Feng

2014-09-01

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

Template-assisted fabrication of tin and antimony based nanowire arrays

Science.gov (United States)

Zaraska, Leszek; Kurowska, Elżbieta; Sulka, Grzegorz D.; Jaskuła, Marian

2012-10-01

Antimony nanowires with diameters ranging from 35 nm to 320 nm were successfully prepared by simple, galvanostatic electrodeposition inside the pores of anodic alumina membranes from a citrate based electrolyte. The use of the potassium antimonyl tartrate electrolyte for electrodeposition results in the formation of Sb/Sb2O3 nanowires. The structural features of the nanowire arrays were investigated by FE-SEM, and the nanowire composition was confirmed by EDS and XRD measurements. A distinct peak at about 27.5° in the XRD pattern recorded for nanowires formed in the tartrate electrolyte was attributed to the presence of co-deposited Sb2O3. Three types of dense arrays of Sn-SnSb nanowires with diameters ranging from 82 nm to 325 nm were also synthesized by DC galvanostatic electrodeposition into the anodic aluminum oxide (AAO) membranes for the first time. Only Sn and SnSb peaks appeared in the XRD pattern and both phases seem to have a relatively high degree of crystallinity. The influence of current density applied during electrodeposition on the composition of nanowires was investigated. It was found that the Sb content in fabricated nanowires decreases with increasing current density. The diameters of all synthesized nanowires roughly correspond to the dimensions of the nanochannels of AAO templates used for electrodeposition.

Focused ion beam patterning to dielectrophoretically assemble single nanowire based devices

International Nuclear Information System (INIS)

La Ferrara, V; Massera, E; Francia, G Di; Alfano, B

2010-01-01

Direct-write processing is increasingly taking place in nanodevice fabrication. In this work, Focused Ion Beam (FIB), a powerful tool in maskless micromachining, is used for electrode patterning onto a silicon/silicon nitride substrate. Then a single palladium nanowire is assembled between electrodes by means of dielectrophoresis (DEP). The nanowire morphology depends on the electrode pattern when DEP conditions are fixed. FIB/DEP combination overcomes the problem of nanowire electrical contamination due to gallium ion bombardment and the as-grown nanowire retains its basic electrical properties. Single nanowire based devices have been fabricated with this novel approach and have been tested as hydrogen sensors, confirming the reliability of this technology.

Self-catalyzed growth of dilute nitride GaAs/GaAsSbN/GaAs core-shell nanowires by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Kasanaboina, Pavan Kumar [Department of Electrical and Computer Engineering, North Carolina A& T State University, Greensboro, North Carolina 27411 (United States); Ahmad, Estiak [Nanoengineering, Joint School of Nanoscience and Nanoengineering, NCA& T State University, Greensboro, North Carolina 27401 (United States); Li, Jia; Iyer, Shanthi [Department of Electrical and Computer Engineering, North Carolina A& T State University, Greensboro, North Carolina 27411 (United States); Nanoengineering, Joint School of Nanoscience and Nanoengineering, NCA& T State University, Greensboro, North Carolina 27401 (United States); Reynolds, C. Lewis; Liu, Yang [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2015-09-07

Bandgap tuning up to 1.3 μm in GaAsSb based nanowires by incorporation of dilute amount of N is reported. Highly vertical GaAs/GaAsSbN/GaAs core-shell configured nanowires were grown for different N contents on Si (111) substrates using plasma assisted molecular beam epitaxy. X-ray diffraction analysis revealed close lattice matching of GaAsSbN with GaAs. Micro-photoluminescence (μ-PL) revealed red shift as well as broadening of the spectra attesting to N incorporation in the nanowires. Replication of the 4K PL spectra for several different single nanowires compared to the corresponding nanowire array suggests good compositional homogeneity amongst the nanowires. A large red shift of the Raman spectrum and associated symmetric line shape in these nanowires have been attributed to phonon localization at point defects. Transmission electron microscopy reveals the dominance of stacking faults and twins in these nanowires. The lower strain present in these dilute nitride nanowires, as opposed to GaAsSb nanowires having the same PL emission wavelength, and the observation of room temperature PL demonstrate the advantage of the dilute nitride system offers in the nanowire configuration, providing a pathway for realizing nanoscale optoelectronic devices in the telecommunication wavelength region.

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

KAUST Repository

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

2017-01-01

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

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

KAUST Repository

Ooi, Boon S.

2017-04-27

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

Fully transparent thin-film transistor devices based on SnO2 nanowires.

Science.gov (United States)

Dattoli, Eric N; Wan, Qing; Guo, Wei; Chen, Yanbin; Pan, Xiaoqing; Lu, Wei

2007-08-01

We report on studies of field-effect transistor (FET) and transparent thin-film transistor (TFT) devices based on lightly Ta-doped SnO2 nano-wires. The nanowire-based devices exhibit uniform characteristics with average field-effect mobilities exceeding 100 cm2/V x s. Prototype nano-wire-based TFT (NW-TFT) devices on glass substrates showed excellent optical transparency and transistor performance in terms of transconductance, bias voltage range, and on/off ratio. High on-currents and field-effect mobilities were obtained from the NW-TFT devices even at low nanowire coverage. The SnO2 nanowire-based TFT approach offers a number of desirable properties such as low growth cost, high electron mobility, and optical transparency and low operation voltage, and may lead to large-scale applications of transparent electronics on diverse substrates.

Synthesis and cathodoluminescence of Sb/P co-doped GaN nanowires

International Nuclear Information System (INIS)

Wang, Zaien; Liu, Baodan; Yuan, Fang; Hu, Tao; Zhang, Guifeng; Dierre, Benjamin; Hirosaki, Naoto; Sekiguchi, Takashi; Jiang, Xin

2014-01-01

Sb/P co-doped Gallium Nitride (GaN) nanowires were synthesized via a simple chemical vapor deposition (CVD) process by heating Ga 2 O 3 and Sb powders in NH 3 atmosphere. Scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDS) measurements confirmed the as-synthesized products were Sb/P co-doped GaN nanowires with rough morphology and hexagonal wurtzite structure. Room temperature cathodoluminescence (CL) demonstrated that an obvious band shift of GaN nanowires can be observed due to Sb/P co-doping. Possible explanation for the growth and luminescence mechanism of Sb/P co-doped GaN nanowires was discussed. Highlight: • Sb/P co-doped GaN nanowires were synthesized through a well-designed multi-channel chemical vapor deposition (CVD) process. • Sb/P co-doping leads to the crystallinity deterioration of GaN nanowires. • Sb/P co-doping caused the red-shift of GaN nanowires band-gap in UV range. • Compared with Sb doping, P atoms are more easy to incorporate into the GaN lattice

What's my line? A narrative review and synthesis of the literature on Registered Nurses' communication behaviours between shifts.

Science.gov (United States)

Kitson, Alison L; Muntlin Athlin, Åsa; Elliott, Janice; Cant, Megan L

2014-06-01

To describe, appraise and synthesize the seminal and empirical literature around Registered Nurses' communication behaviours between shifts in acute hospital settings. Effective communication between shifts (at nursing handover) is acknowledged as a prerequisite to safe and high-quality patient-centred care. However, gaps and inconsistencies continue to prevail. Narrative review and synthesis. The electronic databases PubMED, CINAHL and Scopus were used. English language, peer-reviewed papers published between 1970-April 2012 were considered for review. Criteria included Registered Nurses' communication during handovers in adult hospital settings. Twenty-nine papers were reviewed. The research lacks a clear conceptual framework to define the core purposes of Nurses' communication behaviours between shifts. Seven themes were identified: overall purpose; report givers and receivers; seeing the whole picture; teaching and education; language; patient-centred care; and social cohesion. Two main communication processes are required - one articulating the whole picture and the other detailing information about patients. This area of research is challenged by lack of consistency in terminology and methodological rigour. While recent research has confirmed the findings from the seminal work, it has not been able to elaborate on some of the key challenges to refine the knowledge base. A more integrated approach is required to understand the complex process of improving nursing communication behaviours, particularly around the nursing handover. A neglected area of study is the role of the unit lead in determining the communication standards of the whole nursing team. © 2013 John Wiley & Sons Ltd.

Register-based studies of healthcare costs

DEFF Research Database (Denmark)

Kruse, Marie; Christiansen, Terkel

2011-01-01

Introduction: The aim of this paper is to provide an overview and a few examples of how national registers are used in analyses of healthcare costs in Denmark. Research topics: The paper focuses on health economic analyses based on register data. For the sake of simplicity, the studies are divided...... into three main categories: economic evaluations of healthcare interventions, cost-of-illness analyses, and other analyses such as assessments of healthcare productivity. Conclusion: We examined a number of studies using register-based data on healthcare costs. Use of register-based data renders...

Passive high-frequency devices based on superlattice ferromagnetic nanowires

International Nuclear Information System (INIS)

Ye, B.; Li, F.; Cimpoesu, D.; Wiley, J.B.; Jung, J.-S.; Stancu, A.; Spinu, L.

2007-01-01

In this paper we propose to tailor the bandwidth of a microwave filter by exploitation of shape anisotropy of nanowires. In order to achieve this control of shape anisotropy, we considered superlattice wires containing varying-sized ferromagnetic regions separated by nonferromagnetic regions. Superlattice wires of Ni and Au with a nominal diameter of 200 nm were grown using standard electrodeposition techniques. The microwave properties were probed using X-band (9.8 GHz) ferromagnetic resonance (FMR) experiments performed at room temperature. In order to investigate the effectiveness of the shape anisotropy on the superlattice nanowire based filter the FMR spectrum of superlattice structure is compared to the FMR spectra of nanowires samples with constant length

Template-based fabrication of nanowire-nanotube hybrid arrays

International Nuclear Information System (INIS)

Ye Zuxin; Liu Haidong; Schultz, Isabel; Wu Wenhao; Naugle, D G; Lyuksyutov, I

2008-01-01

The fabrication and structure characterization of ordered nanowire-nanotube hybrid arrays embedded in porous anodic aluminum oxide (AAO) membranes are reported. Arrays of TiO 2 nanotubes were first deposited into the pores of AAO membranes by a sol-gel technique. Co nanowires were then electrochemically deposited into the TiO 2 nanotubes to form the nanowire-nanotube hybrid arrays. Scanning electron microscopy and transmission electron microscopy measurements showed a high nanowire filling factor and a clean interface between the Co nanowire and the TiO 2 nanotube. Application of these hybrids to the fabrication of ordered nanowire arrays with highly controllable geometric parameters is discussed

New surface plasmon polariton waveguide based on GaN nanowires

Directory of Open Access Journals (Sweden)

Jun Zhu

Full Text Available Lasers are nowadays widely used in industry, in hospitals and in many devices that we have at home. Random laser development is challenging given its high threshold and low integration. Surface plasmon polariton (SPP can improve random laser characteristics because of its ability to control diffraction. In this study, we establish a random laser structural model with silicon-based parcel GaN nanowires. The GaN nanowire gain and enhanced surface plasmon increase population inversion level. Our laser model is based on random particle scattering feedback mechanism, nanowire use, and surface plasmon enhancement effect, which causes stochastic laser emergence. Analysis shows that the SPP mode and nanowire waveguides coupled in the dielectric layer of low refractive index can store light energy like a capacitor under low refractive index clearance. The waveguide mode field area and limiting factors show that the modeled laser can achieve sub-wavelength constraints of the output light field. We also investigate emergent laser performance for a more limited light field capacity and lower threshold. Keywords: Random laser, Surface plasmon polariton, Feedback mechanism, Low threshold, Subwavelength constraints

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...... atomic force microscopy and from polarized far-field optical microscopy for various prototypical molecules are reproduced by electrostatic and Monte Carlo calculations. Based on the crystal structure, predictions on the growth habit from other conjugated molecules become in reach....

Understanding the formation process of exceptionally long fullerene-based nanowires

DEFF Research Database (Denmark)

Solov'yov, Ilia; Geng, Junfeng; Solov'yov, Andrey V.

2009-01-01

solution of C$_60$. We have performed a thorough theoretical analysis, aiming at gaining an in-depth understanding of the exceptionally large aspect ratio of C$_60$-based nanowires. By accounting for different interactions in the system we have calculated the structures of the unit cell and determined...... the role of the fullerene and of the solvent molecules in the crystallization process of the nanowires. We have calculated the adhesion energy of C$_60$ molecules to the nanowire surface, and on the basis of this explained the growth anisotropy of the crystal. To get a more profound understanding...

Valence band variation in Si (110) nanowire induced by a covered insulator

International Nuclear Information System (INIS)

Hong-Hua, Xu; Xiao-Yan, Liu; Yu-Hui, He; Gang, Du; Ru-Qi, Han; Jin-Feng, Kang; Chun, Fan; Ai-Dong, Sun

2010-01-01

In this work, we investigate strain effects induced by the deposition of gate dielectrics on the valence band structures in Si (110) nanowire via the simulation of strain distribution and the calculation of a generalized 6×6k·p strained valence band. The nanowire is surrounded by the gate dielectric. Our simulation indicates that the strain of the amorphous SiO 2 insulator is negligible without considering temperature factors. On the other hand, the thermal residual strain in a nanowire with amorphous SiO 2 insulator which has negligible lattice misfit strain pushes the valence subbands upwards by chemical vapour deposition and downwards by thermal oxidation treatment. In contrast with the strain of the amorphous SiO 2 insulator, the strain of the HfO 2 gate insulator in Si (110) nanowire pushes the valence subbands upwards remarkably. The thermal residual strain by HfO 2 insulator contributes to the up-shifting tendency. Our simulation results for valence band shifting and warping in Si nanowires can provide useful guidance for further nanowire device design. (classical areas of phenomenology)

Surface sensitization mechanism on negative electron affinity p-GaN nanowires

Science.gov (United States)

Diao, Yu; Liu, Lei; Xia, Sihao; Feng, Shu; Lu, Feifei

2018-03-01

The surface sensitization is the key to prepare negative electron affinity photocathode. The thesis emphasizes on the study of surface sensitization mechanism of p-type doping GaN nanowires utilizing first principles based on density function theory. The adsorption energy, work function, dipole moment, geometry structure, electronic structure and optical properties of Mg-doped GaN nanowires surfaces with various coverages of Cs atoms are investigated. The GaN nanowire with Mg doped in core position is taken as the sensitization base. At the initial stage of sensitization, the best adsorption site for Cs atom on GaN nanowire surface is BN, the bridge site of two adjacent N atoms. Surface sensitization generates a p-type internal surface with an n-type surface state, introducing a band bending region which can help reduce surface barrier and work function. With increasing Cs coverage, work functions decrease monotonously and the "Cs-kill" phenomenon disappears. For Cs coverage of 0.75 ML and 1 ML, the corresponding sensitization systems reach negative electron affinity state. Through surface sensitization, the absorption curves are red shifted and the absorption coefficient is cut down. All theoretical calculations can guide the design of negative electron affinity Mg doped GaN nanowires photocathode.

Diagnosis of phosphorus monolayer doping in silicon based on nanowire electrical characterisation

Science.gov (United States)

Duffy, Ray; Ricchio, Alessio; Murphy, Ruaidhrí; Maxwell, Graeme; Murphy, Richard; Piaszenski, Guido; Petkov, Nikolay; Hydes, Alan; O'Connell, Dan; Lyons, Colin; Kennedy, Noel; Sheehan, Brendan; Schmidt, Michael; Crupi, Felice; Holmes, Justin D.; Hurley, Paul K.; Connolly, James; Hatem, Chris; Long, Brenda

2018-03-01

The advent of high surface-to-volume ratio devices has necessitated a revised approach to parameter extraction and process evaluation in field-effect transistor technologies. In this work, active doping concentrations are extracted from the electrical analysis of Si nanowire devices with high surface-to-volume ratios. Nanowire resistance and Si resistivity are extracted, by first extracting and subtracting out the contact resistance. Resistivity (ρ) is selected as the benchmark parameter to compare different doping processes with each other. The impacts of nanowire diameter scaling to 10 nm and of nanowire spacing scaling to resistivity and higher dopant activation, with dependencies on the nanowire width greater than on nanowire spacing. Limitations in ADP P monolayer doping with a SiO2 cap are due to the difficulties in dopant incorporation, as it is based on in-diffusion, and P atoms must overcome a potential barrier on the Si surface.

Register-based research on twins

DEFF Research Database (Denmark)

Christensen, Kaare; Ohm Kyvik, Kirsten; Holm, Niels V

2011-01-01

Introduction: The Danish Twin Registry (DTR) has for more than 50 years been based on surveys and clinical investigations and over the two last decades also on register linkage. Currently these two approaches are merged within Statistics Denmark. Research topics: Here we report on three major...... groups of register-based research in the DTR that used the uniqueness of twinning. First, we focus on the ''long-term prognosis'' of being a twin compared with being a singleton and show that Danish twins have health trajectories in adulthood similar to singletons, which is a result of interest for twins...... illustrate how the co-twin control method in a register setting can be used to control for the effect of rearing environment and genetic factors in studies of the association between exposures and health. CONCLUSION: The spectrum of register-based twin studies is very wide and have changed in accordance...

Fast humidity sensors based on CeO2 nanowires

International Nuclear Information System (INIS)

Fu, X Q; Wang, C; Yu, H C; Wang, Y G; Wang, T H

2007-01-01

Fast humidity sensors are reported that are based on CeO 2 nanowires synthesized by a hydrothermal method. Both the response and recovery time are about 3 s, and are independent of the humidity. The sensitivity increases gradually as the humidity increases, and is up to 85 at 97% RH. The resistance decreases exponentially with increasing humidity, implying ion-type conductivity as the humidity sensing mechanism. A model based on the morphology and surface energy of the nanowires is given to explain these results further. Our experimental results indicate a pathway to improving the performance of humidity sensors

Bismuth alloying properties in GaAs nanowires

Energy Technology Data Exchange (ETDEWEB)

Ding, Lu [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, PO Box 72, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, PO Box 72, Beijing 100876 (China); Cao, Huawei; Cai, Ningning; Yu, Zhongyuan [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, PO Box 72, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden)

2013-09-15

First-principles calculations have been performed to investigate the structural, electronic and optical properties of bismuth alloying in GaAs nanowires. A typical model of Ga{sub 31}As{sub 31} nanowires is introduced for its reasonable band gap. The band gap of GaAs{sub 1−x}Bi{sub x} shrinks clearly with the increasing Bi concentration and the band edge shifts when spin–orbit coupling (SOC) is considered. The insertion of Bi atom leads to hybridization of Ga/As/Bi p states which contributes a lot around Fermi level. Scissor effect is involved. The optical properties are presented, including dielectric function, optical absorption spectra and reflectivity, which are also varied with the increasing of Bi concentrations. - Graphical abstract: Top view of Bi-doped GaAs nanowires. Ga, As, and Bi atoms are denoted with grey, purple and red balls, respectively. Display Omitted - Highlights: • A typical model of Ga{sub 31}As{sub 31} nanowires is introduced for its reasonable band gap. • The band gap of GaAs{sub 1−x}Bi{sub x} shrinks clearly with the increasing Bi concentration. • The band edge shifts when spin–orbit coupling (SOC) is considered. • The insertion of Bi atom leads to hybridization of Ga/As/Bi p states.

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

Science.gov (United States)

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

2016-09-27

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

A high-efficiency electrically-pumped single-photon source based on a photonics nanowire

DEFF Research Database (Denmark)

Gregersen, Niels; Nielsen, Torben Roland; Mørk, Jesper

An electrically-pumped single-photon source design with a predicted efficiency of 89% is proposed. The design is based on a quantum dot embedded in a photonic nanowire with tailored ends and optimized contact electrodes. Unlike cavity-based approaches, the photonic nanowire features broadband...

Direction dependence of the magneto-optical absorption in nanowires with Rashba interaction

Energy Technology Data Exchange (ETDEWEB)

Sakr, M.R., E-mail: msakr@alexu.edu.eg

2016-09-16

We study the directional dependence of the absorption spectrum of ballistic nanowires in the presence of gate-controlled Rashba spin–orbit interaction and an in-plane magnetic field. In the weak Rashba regime, our analytical and numerical results show that the absorption peaks associated with the first and third intersubband transitions exhibit frequency shifts and strong amplitude modulations as the direction of the magnetic field changes. If the field is parallel to the nanowire axis, these peaks disappear and the resonance frequencies of the whole absorption spectrum are given merely in terms of the Zeeman splitting and the energy scale characterizing the confinement potential. The second transition has an absorption peak that suffers an opposite frequency shift with amplitude that is largely direction independent. The amplitude modulation and frequency shift of the absorption spectrum is periodic in the angle that the magnetic field makes with the nanowire axis. - Highlights: • Absorption spectrum of the nanowire is calculated in the weak Rashba regime. • First and third absorption peaks show amplitude and frequency modulation. • They disappear if the magnetic field is along the wire axis, forbidden transitions. • The second transition peak shows frequency shift with minor amplitude modulation. • The frequency and amplitude modulations are periodic in the direction of the field.

Visualization of multipolar longitudinal and transversal surface plasmon modes in nanowire dimers.

Science.gov (United States)

Alber, Ina; Sigle, Wilfried; Müller, Sven; Neumann, Reinhard; Picht, Oliver; Rauber, Markus; van Aken, Peter A; Toimil-Molares, Maria Eugenia

2011-12-27

We study the transversal and longitudinal localized surface plasmon resonances in single nanowires and nanowire dimers excited by the fast traveling electron beam in a transmission electron microscope equipped with high-resolution electron energy-loss spectroscopy. Bright and dark longitudinal modes up to the fifth order are resolved on individual metallic nanowires. On nanowire dimers, mode splitting into bonding and antibonding is measured up to the third order for several dimers with various aspect ratio and controlled gap size. We observe that the electric field maxima of the bonding modes are shifted toward the gap, while the electric field maxima of the antibonding modes are shifted toward the dimer ends. Finally, we observe that the transversal mode is not detected in the region of the dimer gap and decays away from the rod more rapidly than the longitudinal modes.

Plasmon-polariton modes of dense Au nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Yan, Hongdan; Lemmens, Peter; Wulferding, Dirk; Cetin, Mehmet Fatih [IPKM, TU-BS, Braunschweig (Germany); Tornow, Sabine; Zwicknagl, Gertrud [IMP, TU-BS, Braunschweig (Germany); Krieg, Ulrich; Pfnuer, Herbert [IFP, LU Hannover (Germany); Daum, Winfried; Lilienkamp, Gerhard [IEPT, TU Clausthal (Germany); Schilling, Meinhard [EMG, TU-BS, Braunschweig (Germany)

2011-07-01

Using optical absorption and other techniques we study plasmon-polariton modes of dense Au nanowire arrays as function of geometrical parameters and coupling to molecular degrees of freedom. For this instance we electrochemically deposit Au nanowires in porous alumina with well controlled morphology and defect concentration. Transverse and longitudinal modes are observed in the absorption spectra resulting from the anisotropic plasmonic structure. The longitudinal mode shows a blue shift of energy with increasing length of the wires due to the more collective nature of this response. We compare our observations with model calculations and corresponding results on 2D Ag nanowire lattices.

Solution-Based Epitaxial Growth of Magnetically Responsive Cu@Ni Nanowires

KAUST Repository

Zhang, Shengmao; Zeng, Hua Chun

2010-01-01

An experiment was conducted to show the solution-based epitaxial growth of magnetically responsive Cu@Ni nanowires. The Ni-sheathed Cu nanowires were synthesized with a one-pot approach. 30 mL of high concentration NaOH, Cu(NO3)2. 3H2O, Cu(NO3)2. 3H2O and 0.07-0.30 mL of Ni(NO3)2. 6H 2O aqueous solutions were added into a plastic reactor with a capacity of 50.0 mL. A varying amount of ethylenediamine (EDA) and hydrazine were also added sequentially, followed by thorough mixing of all reagents. The dimension, morphology, and chemical composition of the products were examined with scanning electron microscopy with energy dispersive X-ray spectroscopy. The XPS analysis on the as formed Cu nanowires confirms that there is indeed no nickel inclusion in the nanowires prior to the formation of nickel overcoat, which rules out the possibility of Cu-Ni alloy formation.

Solution-Based Epitaxial Growth of Magnetically Responsive Cu@Ni Nanowires

KAUST Repository

Zhang, Shengmao

2010-02-23

An experiment was conducted to show the solution-based epitaxial growth of magnetically responsive Cu@Ni nanowires. The Ni-sheathed Cu nanowires were synthesized with a one-pot approach. 30 mL of high concentration NaOH, Cu(NO3)2. 3H2O, Cu(NO3)2. 3H2O and 0.07-0.30 mL of Ni(NO3)2. 6H 2O aqueous solutions were added into a plastic reactor with a capacity of 50.0 mL. A varying amount of ethylenediamine (EDA) and hydrazine were also added sequentially, followed by thorough mixing of all reagents. The dimension, morphology, and chemical composition of the products were examined with scanning electron microscopy with energy dispersive X-ray spectroscopy. The XPS analysis on the as formed Cu nanowires confirms that there is indeed no nickel inclusion in the nanowires prior to the formation of nickel overcoat, which rules out the possibility of Cu-Ni alloy formation.

Tunable strain gauges based on two-dimensional silver nanowire networks

International Nuclear Information System (INIS)

Ho, Xinning; Cheng, Chek Kweng; Tey, Ju Nie; Wei, Jun

2015-01-01

Strain gauges are used in various applications such as wearable strain gauges and strain gauges in airplanes or structural health monitoring. Sensitivity of the strain gauge required varies, depending on the application of the strain gauge. This paper reports a tunable strain gauge based on a two-dimensional percolative network of silver nanowires. By varying the surface coverage of the nanowire network and the waviness of the nanowires in the network, the sensitivity of the strain gauge can be controlled. Hence, a tunable strain gauge can be engineered, based on demands of the application. A few applications are demonstrated. The strain gauge can be adhered to the human neck to detect throat movements and a glove integrated with such a strain gauge can detect the bending of the forefinger. Other classes of two-dimensional percolative networks of one-dimensional materials are also expected to exhibit similar tunable properties. (paper)

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

Energy Technology Data Exchange (ETDEWEB)

Fountaine, Katherine T., E-mail: kfountai@caltech.edu [Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Whitney, William S. [Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Department of Physics, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Atwater, Harry A. [Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Department of Applied Physics and Materials Science, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States)

2014-10-21

We present a unified framework for resonant absorption in periodic arrays of high index semiconductor nanowires that combines a leaky waveguide theory perspective and that of photonic crystals supporting Bloch modes, as array density transitions from sparse to dense. Full dispersion relations are calculated for each mode at varying illumination angles using the eigenvalue equation for leaky waveguide modes of an infinite dielectric cylinder. The dispersion relations along with symmetry arguments explain the selectivity of mode excitation and spectral red-shifting of absorption for illumination parallel to the nanowire axis in comparison to perpendicular illumination. Analysis of photonic crystal band dispersion for varying array density illustrates that the modes responsible for resonant nanowire absorption emerge from the leaky waveguide modes.

Surface effects on static bending of nanowires based on non-local elasticity theory

Directory of Open Access Journals (Sweden)

Quan Wu

2015-10-01

Full Text Available The surface elasticity and non-local elasticity effects on the elastic behavior of statically bent nanowires are investigated in the present investigation. Explicit solutions are presented to evaluate the surface stress and non-local elasticity effects with various boundary conditions. Compared with the classical Euler beam, a nanowire with surface stress and/or non-local elasticity can be either stiffer or less stiff, depending on the boundary conditions. The concept of surface non-local elasticity was proposed and its physical interpretation discussed to explain the combined effect of surface elasticity and non-local elasticity. The effect of the nanowire size on its elastic bending behavior was investigated. The results obtained herein are helpful to characterize mechanical properties of nanowires and aid nanowire-based devices design.

Nanolithography based contacting method for electrical measurements on single template synthesized nanowires

DEFF Research Database (Denmark)

Fusil, S.; Piraux, L.; Mátéfi-Tempfli, Stefan

2005-01-01

A reliable method enabling electrical measurements on single nanowires prepared by electrodeposition in an alumina template is described. This technique is based on electrically controlled nanoindentation of a thin insulating resist deposited on the top face of the template filled by the nanowires....... We show that this method is very flexible, allowing us to electrically address single nanowires of controlled length down to 100 nm and of desired composition. Using this approach, current densities as large as 10 A cm were successfully injected through a point contact on a single magnetic...

Estimating the Dieaway Time and its Precision from Shift Register Data

Energy Technology Data Exchange (ETDEWEB)

Croft, S.; Evans, L. G.; Henzlova, D.; Miller, K. A. [Los Alamos National Laboratory, Nuclear Nonproliferation Division, Safeguards Science and Technology Group, Los Alamos (United States)

2012-06-15

Neutron coincidence counting is widely used throughout the nuclear fuel cycle to quantify special nuclear materials that fission, for example Pu. Before calibration and setting to work, instruments undergo a range of performance and characterization tests that typically include measurement of the neutron dieaway characteristic. The neutron dieaway characteristic is a general measure of the likelihood that a neutron will be detected following another neutron, and describes time behavior of detected neutrons in the assay system. This paper shows how the effective 1/ecapture dieaway time of the observable coincidence (doubles) rate may be extracted simply and quickly from two coincidence counting rates recorded with different shift register time gate settings. In particular we address how to assign the precision to such estimates including when the rates are correlated.

Lateral nanowire/nanobelt based nanogenerators, piezotronics and piezo-phototronics

KAUST Repository

Wang, Zhong Lin

2010-11-01

Relying on the piezopotential created in ZnO under straining, nanogenerators, piezotronics and piezo-phototronics developed based on laterally bonded nanowires on a polymer substrate have been reviewed. The principle of the nanogenerator is a transient flow of electrons in external load as driven by the piezopotential created by dynamic straining. By integrating the contribution made by millions of nanowires, the output voltage has been raised to 1.2 V. Consequently, self-powered nanodevices have been demonstrated. This is an important platform technology for the future sensor network and the internet of things. Alternatively, the piezopotential can act as a gate voltage that can tune/gate the transport process of the charge carriers in the nanowire, which is a gate-electrode free field effect transistor (FET). The device fabricated based on this principle is called the piezotronic device. Piezo-phototronic effect is about the tuning and controlling of electro-optical processes by strain induced piezopotential. The piezotronic, piezophotonic and pieozo-phototronic devices are focused on low frequency applications in areas involving mechanical actions, such as MEMS/NEMS, nanorobotics, sensors, actuators and triggers. © 2010 Elsevier B.V. All rights reserved.

Mode tunable p-type Si nanowire transistor based zero drive load logic inverter.

Science.gov (United States)

Moon, Kyeong-Ju; Lee, Tae-Il; Lee, Sang-Hoon; Han, Young-Uk; Ham, Moon-Ho; Myoung, Jae-Min

2012-07-25

A design platform for a zero drive load logic inverter consisting of p-channel Si nanowire based transistors, which controlled their operating mode through an implantation into a gate dielectric layer was demonstrated. As a result, a nanowire based class D inverter having a 4.6 gain value at V(DD) of -20 V was successfully fabricated on a substrate.

Vertical architecture for enhancement mode power transistors based on GaN nanowires

Science.gov (United States)

Yu, F.; Rümmler, D.; Hartmann, J.; Caccamo, L.; Schimpke, T.; Strassburg, M.; Gad, A. E.; Bakin, A.; Wehmann, H.-H.; Witzigmann, B.; Wasisto, H. S.; Waag, A.

2016-05-01

The demonstration of vertical GaN wrap-around gated field-effect transistors using GaN nanowires is reported. The nanowires with smooth a-plane sidewalls have hexagonal geometry made by top-down etching. A 7-nanowire transistor exhibits enhancement mode operation with threshold voltage of 1.2 V, on/off current ratio as high as 108, and subthreshold slope as small as 68 mV/dec. Although there is space charge limited current behavior at small source-drain voltages (Vds), the drain current (Id) and transconductance (gm) reach up to 314 mA/mm and 125 mS/mm, respectively, when normalized with hexagonal nanowire circumference. The measured breakdown voltage is around 140 V. This vertical approach provides a way to next-generation GaN-based power devices.

CMOS-compatible fabrication of top-gated field-effect transistor silicon nanowire-based biosensors

International Nuclear Information System (INIS)

Ginet, Patrick; Akiyama, Sho; Takama, Nobuyuki; Fujita, Hiroyuki; Kim, Beomjoon

2011-01-01

Field-effect transistor (FET) nanowire-based biosensors are very promising tools for medical diagnosis. In this paper, we introduce a simple method to fabricate FET silicon nanowires using only standard microelectromechanical system (MEMS) processes. The key steps of our fabrication process were a local oxidation of silicon (LOCOS) and anisotropic KOH etchings that enabled us to reduce the width of the initial silicon structures from 10 µm to 170 nm. To turn the nanowires into a FET, a top-gate electrode was patterned in gold next to them in order to apply the gate voltage directly through the investigated liquid environment. An electrical characterization demonstrated the p-type behaviour of the nanowires. Preliminary chemical sensing tested the sensitivity to pH of our device. The effect of the binding of streptavidin on biotinylated nanowires was monitored in order to evaluate their biosensing ability. In this way, streptavidin was detected down to a 100 ng mL −1 concentration in phosphate buffered saline by applying a gate voltage less than 1.2 V. The use of a top-gate electrode enabled the detection of biological species with only very low voltages that were compatible with future handheld-requiring applications. We thus demonstrated the potential of our devices and their fabrication as a solution for the mass production of efficient and reliable FET nanowire-based biological sensors

Ballistic Spin Field Effect Transistor Based on Silicon Nanowires

Science.gov (United States)

Osintsev, Dmitri; Sverdlov, Viktor; Stanojevic, Zlatan; Selberherr, Siegfried

2011-03-01

We investigate the properties of ballistic spin field-effect transistors build on silicon nanowires. An accurate description of the conduction band based on the k . p} model is necessary in thin and narrow silicon nanostructures. The subband effective mass and subband splitting dependence on the nanowire dimensions is analyzed and used in the transport calculations. The spin transistor is formed by sandwiching the nanowire between two ferromagnetic metallic contacts. Delta-function barriers at the interfaces between the contacts and the silicon channel are introduced. The major contribution to the electric field-dependent spin-orbit interaction in confined silicon systems is due to the interface-induced inversion asymmetry which is of the Dresselhaus type. We study the current and conductance through the system for the contacts being in parallel and anti-parallel configurations. Differences between the [100] and [110] orientated structures are investigated in details. This work is supported by the European Research Council through the grant #247056 MOSILSPIN.

Carrier gas effects on aluminum-catalyzed nanowire growth

International Nuclear Information System (INIS)

Ke, Yue; Hainey, Mel Jr; Won, Dongjin; Weng, Xiaojun; Eichfeld, Sarah M; Redwing, Joan M

2016-01-01

Aluminum-catalyzed silicon nanowire growth under low-pressure chemical vapor deposition conditions requires higher reactor pressures than gold-catalyzed growth, but the reasons for this difference are not well understood. In this study, the effects of reactor pressure and hydrogen partial pressure on silicon nanowire growth using an aluminum catalyst were studied by growing nanowires in hydrogen and hydrogen/nitrogen carrier gas mixtures at different total reactor pressures. Nanowires grown in the nitrogen/hydrogen mixture have faceted catalyst droplet tips, minimal evidence of aluminum diffusion from the tip down the nanowire sidewalls, and significant vapor–solid deposition of silicon on the sidewalls. In comparison, wires grown in pure hydrogen show less well-defined tips, evidence of aluminum diffusion down the nanowire sidewalls at increasing reactor pressures and reduced vapor–solid deposition of silicon on the sidewalls. The results are explained in terms of a model wherein the hydrogen partial pressure plays a critical role in aluminum-catalyzed nanowire growth by controlling hydrogen termination of the silicon nanowire sidewalls. For a given reactor pressure, increased hydrogen partial pressures increase the extent of hydrogen termination of the sidewalls which suppresses SiH_4 adsorption thereby reducing vapor–solid deposition of silicon but increases the surface diffusion length of aluminum. Conversely, lower hydrogen partial pressures reduce the hydrogen termination and also increase the extent of SiH_4 gas phase decomposition, shifting the nanowire growth window to lower growth temperatures and silane partial pressures. (paper)

Molybdenum oxide nanowires based supercapacitors with enhanced capacitance and energy density in ethylammonium nitrate electrolyte

Energy Technology Data Exchange (ETDEWEB)

Sarfraz, Mansoor; Aboud, Mohamed F.A.; Shakir, Imran, E-mail: shakir@skku.edu

2015-11-25

Orthorhombic molybdenum trioxide (α-MoO{sub 3}) nanowires as an electrode for electrochemical supercapacitors in ethylammonium nitrate (EAN) electrolyte exhibits a high specific capacitance of 288 Fg{sup −1}, which is 8 times higher than the specific capacitance obtained from MoO{sub 3} nanowires in water based electrolyte. MoO{sub 3} nanowires in EAN electrolyte exhibit energy density of 46.32 Wh kg{sup −1} at a power density of 20.3 kW kg{sup −1} with outstanding cycling stability with specific capacitance retention of 96% over 3000 cycles. We believe that the superior performance of the MoO{sub 3} nanowires in EAN based electrolyte is primarily due to its relatively low viscosity (0.28 P at 25 °C), high electrical conductivity (20 mS cm{sup −1} at 25 °C) and large working voltage window. The results clearly demonstrate that EAN as electrolyte is one of the most promising electrolyte for high performance large scale energy storage devices. - Highlights: • Synthesis of single crystalline molybdenum oxide nanowires. • Ethylammonium Nitrate as an electrolyte for high performance large scale psuedocapacitor based energy storage devices. • Molybdenum oxide nanowires based electrodes shows 8 fold enhancement in Ethylammonium Nitrate electrolyte as compared to water based electrolytes. • The devices in Ethylammonium Nitrate exhibit excellent stability, retaining 96% of its initial capacity after 3000 cycles.

The Joule heating problem in silver nanowire transparent electrodes

Science.gov (United States)

Khaligh, H. H.; Xu, L.; Khosropour, A.; Madeira, A.; Romano, M.; Pradére, C.; Tréguer-Delapierre, M.; Servant, L.; Pope, M. A.; Goldthorpe, I. A.

2017-10-01

Silver nanowire transparent electrodes have shown considerable potential to replace conventional transparent conductive materials. However, in this report we show that Joule heating is a unique and serious problem with these electrodes. When conducting current densities encountered in organic solar cells, the average surface temperature of indium tin oxide (ITO) and silver nanowire electrodes, both with sheet resistances of 60 ohms/square, remains below 35 °C. However, in contrast to ITO, the temperature in the nanowire electrode is very non-uniform, with some localized points reaching temperatures above 250 °C. These hotspots accelerate nanowire degradation, leading to electrode failure after 5 days of continuous current flow. We show that graphene, a commonly used passivation layer for these electrodes, slows nanowire degradation and creates a more uniform surface temperature under current flow. However, the graphene does not prevent Joule heating in the nanowires and local points of high temperature ultimately shift the failure mechanism from nanowire degradation to melting of the underlying plastic substrate. In this paper, surface temperature mapping, lifetime testing under current flow, post-mortem analysis, and modelling illuminate the behaviour and failure mechanisms of nanowires under extended current flow and provide guidelines for managing Joule heating.

Novel Flame-Based Synthesis of Nanowires for Multifunctional Application

Science.gov (United States)

2015-05-13

pattern (SAED) of SnO2/WO2.9 heterojunction for case 7. TEM (Fig. 14(a)) reveals that the coating on the tungsten- oxide nanowires is actually a...tungsten oxide nanowire,s resulting in radial growth of Zn2SnO4 nanocube/WO2.9 nanowire heterojunction . Furthermore, the combined flame and solution...SECURITY CLASSIFICATION OF: Progress for the project has been made in various areas. Specifically, we report on: (i) flame synthesis of metal- oxide

Catalog of 199 register-based definitions of chronic conditions

DEFF Research Database (Denmark)

Hvidberg, Michael F; Johnsen, Søren P; Glümer, Charlotte

2016-01-01

INTRODUCTION: The aim of the current study was to present and discuss a broad range of register-based definitions of chronic conditions for use in register research, as well as the challenges and pitfalls when defining chronic conditions by the use of registers. MATERIALS AND METHODS: The definit......INTRODUCTION: The aim of the current study was to present and discuss a broad range of register-based definitions of chronic conditions for use in register research, as well as the challenges and pitfalls when defining chronic conditions by the use of registers. MATERIALS AND METHODS......: The definitions were defined based on information from nationwide Danish public healthcare registers. Medical and epidemiological specialists identified and grouped relevant diagnosis codes that covered chronic conditions, using the International Classification System version 10 (ICD-10). Where relevant...... definitions were proposed based on record linkage between multiple registers, including registers of prescribed drugs and use of general practitioners' services. CONCLUSIONS THIS STUDY PROVIDED A CATALOG OF REGISTER-BASED DEFINITIONS FOR CHRONIC CONDITIONS FOR USE IN HEALTHCARE PLANNING AND RESEARCH, WHICH IS...

Blue electroluminescence nanodevice prototype based on vertical ZnO nanowire/polymer film on silicon substrate

International Nuclear Information System (INIS)

He Ying; Wang Junan; Chen Xiaoban; Zhang Wenfei; Zeng Xuyu; Gu Qiuwen

2010-01-01

We present a polymer-complexing soft template technique to construct the ZnO-nanowire/polymer light emitting device prototype that exhibits blue electrically driven emission with a relatively low-threshold voltage at room temperature in ambient atmosphere, and the ZnO-nanowire-based LED's emission wavelength is easily tuned by controlling the applied-excitation voltage. The nearly vertically aligned ZnO-nanowires with polymer film were used as emissive layers in the devices. The method uses polymer as binder in the LED device and dispersion medium in the luminescence layer, which stabilizes the quasi-arrays of ZnO nanowires embedding in a thin polymer film on silicon substrate and passivates the surface of ZnO nanocrystals, to prevent the quenching of luminescence. Additionally, the measurements of electrical properties showed that ZnO-nanowire/polymer film could significantly improve the conductivity of the film, which could be attributed to an increase in both Hall mobility and carrier concentration. The results indicated that the novel technique is a low-cost process for ZnO-based UV or blue light emission and reduces the requirement for achieving robust p-doping of ZnO film. It suggests that such ZnO-nanowire/polymer-based LEDs will be suitable for the electro-optical application.

Nanowire Growth for Photovoltaics

DEFF Research Database (Denmark)

Holm, Jeppe Vilstrup

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

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

Science.gov (United States)

2014-01-01

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

Modal analysis of the thermal conductivity of nanowires: examining unique thermal transport features

Science.gov (United States)

Samaraweera, Nalaka; Larkin, Jason M.; Chan, Kin L.; Mithraratne, Kumar

2018-06-01

In this study, unique thermal transport features of nanowires over bulk materials are investigated using a combined analysis based on lattice dynamics and equilibrium molecular dynamics (EMD). The evaluation of the thermal conductivity (TC) of Lenard–Jones nanowires becomes feasible due to the multi-step normal mode decomposition (NMD) procedure implemented in the study. A convergence issue of the TC of nanowires is addressed by the NMD implementation for two case studies, which employ pristine nanowires (PNW) and superlattice nanowires. Interestingly, mode relaxation times at low frequencies of acoustic branches exhibit signs of approaching constant values, thus indicating the convergence of TC. The TC evaluation procedure is further verified by implementing EMD-based Green–Kubo analysis, which is based on a fundamentally different physical perspective. Having verified the NMD procedure, the non-monotonic trend of the TC of nanowires is addressed. It is shown that the principal cause for the observed trend is due to the competing effects of long wavelength phonons and phonon–surface scatterings as the nanowire’s cross-sectional width is changed. A computational procedure is developed to decompose the different modal contribution to the TC of shell alloy nanowires (SANWs) using virtual crystal NMD and the Allen–Feldman theory. Several important conclusions can be drawn from the results. A propagons to non-propagons boundary appeared, resulting in a cut-off frequency (ω cut); moreover, as alloy atomic mass is increased, ω cut shifts to lower frequencies. The existence of non-propagons partly causes the low TC of SANWs. It can be seen that modes with low frequencies demonstrate a similar behavior to corresponding modes of PNWs. Moreover, lower group velocities associated with higher alloy atomic mass resulted in a lower TC of SANWs.

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

International Nuclear Information System (INIS)

Hertenberger, Simon

2012-01-01

by TEM and XRD analysis revealing a disordered wurtzite (WZ) structure with stacking faults occurring every few monolayers to nanometers for InAs nanowires grown under different As/In ratios. However, the nanowire growth temperature is found to influence the crystal structure more significantly, such that longer phase pure WZ segments up to lengths of >10 nm are observed for elevated growth temperatures (≥530 C). Furthermore, InAs nanowire ensembles with different diameter (40-135 nm) are investigated by low-temperature PL spectroscopy. The nanowires show relatively strong emission efficiency, characteristic red-shift with temperature and low-temperature band-edge energy position of ∝0.41 eV for thick nanowires. Reduction in nanowire diameter yields a characteristic blue-shift which is related to quantum confinement effects as confirmed by simulations. The good control about In(Ga)As nanowire growth on Si and the obtained understanding of important physical properties as discussed in this thesis provide a valuable basis for the development of effective high-quality nanowire-based devices.

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

Energy Technology Data Exchange (ETDEWEB)

Hertenberger, Simon

2012-10-15

microstructure are investigated by TEM and XRD analysis revealing a disordered wurtzite (WZ) structure with stacking faults occurring every few monolayers to nanometers for InAs nanowires grown under different As/In ratios. However, the nanowire growth temperature is found to influence the crystal structure more significantly, such that longer phase pure WZ segments up to lengths of >10 nm are observed for elevated growth temperatures (≥530 C). Furthermore, InAs nanowire ensembles with different diameter (40-135 nm) are investigated by low-temperature PL spectroscopy. The nanowires show relatively strong emission efficiency, characteristic red-shift with temperature and low-temperature band-edge energy position of ∝0.41 eV for thick nanowires. Reduction in nanowire diameter yields a characteristic blue-shift which is related to quantum confinement effects as confirmed by simulations. The good control about In(Ga)As nanowire growth on Si and the obtained understanding of important physical properties as discussed in this thesis provide a valuable basis for the development of effective high-quality nanowire-based devices.

A nanowire magnetic memory cell based on a periodic magnetic superlattice

International Nuclear Information System (INIS)

Song, J-F; Bird, J P; Ochiai, Y

2005-01-01

We analyse the operation of a semiconductor nanowire-based memory cell. Large changes in the nanowire conductance result when the magnetization of a periodic array of nanoscale magnetic gates, which comprise the other key component of the memory cell, is switched between distinct configurations by an external magnetic field. The resulting conductance change provides the basis for a robust memory effect, which can be implemented in a semiconductor structure compatible with conventional semiconductor integrated circuits

Polarization Insensitive Wavelength Conversion Based on Four-Wave Mixing in a Silicon Nanowire

DEFF Research Database (Denmark)

Pu, Minhao; Hu, Hao; Peucheret, Christophe

2012-01-01

We experimentally demonstrate, for the first time, polarization-insensitive wavelength conversion of a 10 Gb/s NRZ-OOK data signal based on four-wave mixing in a silicon nanowire with bit-error rate measurements.......We experimentally demonstrate, for the first time, polarization-insensitive wavelength conversion of a 10 Gb/s NRZ-OOK data signal based on four-wave mixing in a silicon nanowire with bit-error rate measurements....

Quantifying signal changes in nano-wire based biosensors

DEFF Research Database (Denmark)

De Vico, Luca; Sørensen, Martin Hedegård; Iversen, Lars

2011-01-01

In this work, we present a computational methodology for predicting the change in signal (conductance sensitivity) of a nano-BioFET sensor (a sensor based on a biomolecule binding another biomolecule attached to a nano-wire field effect transistor) upon binding its target molecule. The methodolog...

Homojunction p-n photodiodes based on As-doped single ZnO nanowire

International Nuclear Information System (INIS)

Cho, H. D.; Zakirov, A. S.; Yuldashev, Sh. U.; Kang, T. W.; Ahn, C. W.; Yeo, Y. K.

2013-01-01

Photovoltaic device was successfully grown solely based on the single ZnO p-n homojunction nanowire. The ZnO nanowire p-n diode consists of an as-grown n-type segment and an in-situ arsenic doped p-type segment. This p-n homojunction acts as a good photovoltaic cell, producing a photocurrent almost 45 times larger than the dark current under reverse-biased condition. Our results demonstrate that present ZnO p-n homojunction nanowire can be used as a self-powered ultraviolet photodetector as well as a photovoltaic cell, which can also be used as an ultralow electrical power source for nano-scale electronic, optoelectronic, and medical devices

A binary-decision-diagram-based two-bit arithmetic logic unit on a GaAs-based regular nanowire network with hexagonal topology

International Nuclear Information System (INIS)

Zhao Hongquan; Kasai, Seiya; Shiratori, Yuta; Hashizume, Tamotsu

2009-01-01

A two-bit arithmetic logic unit (ALU) was successfully fabricated on a GaAs-based regular nanowire network with hexagonal topology. This fundamental building block of central processing units can be implemented on a regular nanowire network structure with simple circuit architecture based on graphical representation of logic functions using a binary decision diagram and topology control of the graph. The four-instruction ALU was designed by integrating subgraphs representing each instruction, and the circuitry was implemented by transferring the logical graph structure to a GaAs-based nanowire network formed by electron beam lithography and wet chemical etching. A path switching function was implemented in nodes by Schottky wrap gate control of nanowires. The fabricated circuit integrating 32 node devices exhibits the correct output waveforms at room temperature allowing for threshold voltage variation.

Electrochemically grown rough-textured nanowires

International Nuclear Information System (INIS)

Tyagi, Pawan; Postetter, David; Saragnese, Daniel; Papadakis, Stergios J.; Gracias, David H.

2010-01-01

Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)-Au plating solution mixture that precipitates an Ag-Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices.

A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device

International Nuclear Information System (INIS)

Lambropoulos, Nicholas A; Reimers, Jeffrey R; Crossley, Maxwell J; Hush, Noel S; Silverbrook, Kia

2013-01-01

A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology. (paper)

A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device

Science.gov (United States)

Lambropoulos, Nicholas A.; Reimers, Jeffrey R.; Crossley, Maxwell J.; Hush, Noel S.; Silverbrook, Kia

2013-12-01

A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology.

A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device.

Science.gov (United States)

Lambropoulos, Nicholas A; Reimers, Jeffrey R; Crossley, Maxwell J; Hush, Noel S; Silverbrook, Kia

2013-12-20

A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology.

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).

Flexible transparent conductive materials based on silver nanowire networks: a review

International Nuclear Information System (INIS)

Langley, Daniel; Giusti, Gaël; Bellet, Daniel; Mayousse, Céline; Celle, Caroline; Simonato, Jean-Pierre

2013-01-01

The class of materials combining high electrical or thermal conductivity, optical transparency and flexibility is crucial for the development of many future electronic and optoelectronic devices. Silver nanowire networks show very promising results and represent a viable alternative to the commonly used, scarce and brittle indium tin oxide. The science and technology research of such networks are reviewed to provide a better understanding of the physical and chemical properties of this nanowire-based material while opening attractive new applications. (topical review)

Universal Verification Methodology Based Register Test Automation Flow.

Science.gov (United States)

Woo, Jae Hun; Cho, Yong Kwan; Park, Sun Kyu

2016-05-01

In today's SoC design, the number of registers has been increased along with complexity of hardware blocks. Register validation is a time-consuming and error-pron task. Therefore, we need an efficient way to perform verification with less effort in shorter time. In this work, we suggest register test automation flow based UVM (Universal Verification Methodology). UVM provides a standard methodology, called a register model, to facilitate stimulus generation and functional checking of registers. However, it is not easy for designers to create register models for their functional blocks or integrate models in test-bench environment because it requires knowledge of SystemVerilog and UVM libraries. For the creation of register models, many commercial tools support a register model generation from register specification described in IP-XACT, but it is time-consuming to describe register specification in IP-XACT format. For easy creation of register model, we propose spreadsheet-based register template which is translated to IP-XACT description, from which register models can be easily generated using commercial tools. On the other hand, we also automate all the steps involved integrating test-bench and generating test-cases, so that designers may use register model without detailed knowledge of UVM or SystemVerilog. This automation flow involves generating and connecting test-bench components (e.g., driver, checker, bus adaptor, etc.) and writing test sequence for each type of register test-case. With the proposed flow, designers can save considerable amount of time to verify functionality of registers.

Bi-stable vocal fold adduction: a mechanism of modal-falsetto register shifts and mixed registration.

Science.gov (United States)

Titze, Ingo R

2014-04-01

The origin of vocal registers has generally been attributed to differential activation of cricothyroid and thyroarytenoid muscles in the larynx. Register shifts, however, have also been shown to be affected by glottal pressures exerted on vocal fold surfaces, which can change with loudness, pitch, and vowel. Here it is shown computationally and with empirical data that intraglottal pressures can change abruptly when glottal adductory geometry is changed relatively smoothly from convergent to divergent. An intermediate shape between large convergence and large divergence, namely, a nearly rectangular glottal shape with almost parallel vocal fold surfaces, is associated with mixed registration. It can be less stable than either of the highly angular shapes unless transglottal pressure is reduced and upper stiffness of vocal fold tissues is balanced with lower stiffness. This intermediate state of adduction is desirable because it leads to a low phonation threshold pressure with moderate vocal fold collision. Achieving mixed registration consistently across wide ranges of F0, lung pressure, and vocal tract shapes appears to be a balancing act of coordinating laryngeal muscle activation with vocal tract pressures. Surprisingly, a large transglottal pressure is not facilitative in this process, exacerbating the bi-stable condition and the associated register contrast.

Nanowire-based gas sensors

NARCIS (Netherlands)

Chen, X.; Wong, C.K.Y.; Yuan, C.A.; Zhang, G.

2013-01-01

Gas sensors fabricated with nanowires as the detecting elements are powerful due to their many improved characteristics such as high surface-to-volume ratios, ultrasensitivity, higher selectivity, low power consumption, and fast response. This paper gives an overview on the recent process of the

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

Science.gov (United States)

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

2018-01-01

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

WPG-Controlled Quantum BDD Circuits with BDD Architecture on GaAs-Based Hexagonal Nanowire Network Structure

Directory of Open Access Journals (Sweden)

Hong-Quan ZHao

2012-01-01

Full Text Available One-dimensional nanowire quantum devices and basic quantum logic AND and OR unit on hexagonal nanowire units controlled by wrap gate (WPG were designed and fabricated on GaAs-based one-dimensional electron gas (1-DEG regular nanowire network with hexagonal topology. These basic quantum logic units worked correctly at 35 K, and clear quantum conductance was achieved on the node device, logic AND circuit unit, and logic OR circuit unit. Binary-decision-diagram- (BDD- based arithmetic logic unit (ALU is realized on GaAs-based regular nanowire network with hexagonal topology by the same fabrication method as that of the quantum devices and basic circuits. This BDD-based ALU circuit worked correctly at room temperature. Since these quantum devices and circuits are basic units of the BDD ALU combinational circuit, the possibility of integrating these quantum devices and basic quantum circuits into the BDD-based quantum circuit with more complicated structures was discussed. We are prospecting the realization of quantum BDD combinational circuitries with very small of energy consumption and very high density of integration.

Flexible Piezoelectric-Induced Pressure Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures.

Science.gov (United States)

Chen, Zefeng; Wang, Zhao; Li, Xinming; Lin, Yuxuan; Luo, Ningqi; Long, Mingzhu; Zhao, Ni; Xu, Jian-Bin

2017-05-23

The piezoelectric effect is widely applied in pressure sensors for the detection of dynamic signals. However, these piezoelectric-induced pressure sensors have challenges in measuring static signals that are based on the transient flow of electrons in an external load as driven by the piezopotential arisen from dynamic stress. Here, we present a pressure sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-induced polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene pressure sensors, this sensor is capable of measuring static pressures with a sensitivity of up to 9.4 × 10 -3 kPa -1 and a fast response time down to 5-7 ms. This demonstration of pressure sensors shows great potential in the applications of electronic skin and wearable devices.

Register-based studies on migration, ethnicity, and health

DEFF Research Database (Denmark)

Norredam, Marie; Kastrup, Marianne; Helweg-Larsen, Karin

2011-01-01

INTRODUCTION: Researchers in Denmark have unique possibilities of register-based research in relation to migration, ethnicity, and health. This review article outlines how these opportunities have been used, so far, by presenting a series of examples. RESEARCH TOPICS: We selected six registers...... it discriminatory. Although, we do not register ethnicity in relation to use of health care in Denmark, our possibilities of linkage between population registers and registers on diseases and healthcare utilisation appear to render the same potentials....... to highlight the process of how migrant study populations have been established and studied in relation to different registers: The Danish Cancer Registry, the Danish Central Psychiatric Research Register, the Danish National Patient Register, the Danish National Health Service Register, the Danish Injury...

Effect of stacking faults on the magnetocrystalline anisotropy of hcp Co-based nanowires

Energy Technology Data Exchange (ETDEWEB)

Kha, Tuan Mai; Schoenstein, Frédéric; Zighem, Fatih [Laboratoire des Sciences des Procédés et des Matériaux (LSPM-UPR3407), CNRS-Université Paris XIII, Sorbonne Paris Cité, Villetaneuse (France); Nowak, Sophie [Université Paris Diderot, Sorbonne Paris Cité, ITODYS, CNRS UMR 7086, 15 rue J.-A. de Baïf, 75205 Paris Cedex 13 (France); Leridon, Brigitte [LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC, F-75005 Paris (France); Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux (LSPM-UPR3407), CNRS-Université Paris XIII, Sorbonne Paris Cité, Villetaneuse (France); Mercone, Silvana, E-mail: silvana.mercone@univ-paris13.fr [Laboratoire des Sciences des Procédés et des Matériaux (LSPM-UPR3407), CNRS-Université Paris XIII, Sorbonne Paris Cité, Villetaneuse (France)

2017-01-15

Replacing materials based on rare-earth elements in current permanent magnets is a real scientific, economic and environmental challenge. Ferromagnetic 3d transition metals seem an apt direction to go in this field, due to their high residual magnetization and thermal stability. In order to improve their coercive behavior, nanostructured magnets based on the assembly of high-aspect-ratio nanoparticles (i.e. cobalt based nanorods and nanowires) have recently been proposed. In these, the nanoparticle morphology itself drives the magnetization reversal mechanism. This purely geometrical effect seems to obscure the effects of structural defects, although it is clear that high magnetocrystalline energy is required to maintain a stable orientation of the magnetic moment inside the nanoparticles. We present here an experimental study whose aim is to distinguish the role of the stacking faults from the effects of shape and morphology on the magnetization reversal mechanism in cobalt-based nanowires. Coercive field results have been obtained on Co{sub 80}Ni{sub 20} nanowires synthesized by a polyol process. Through accurate control of shape and morphology, it was possible to discard the effects of shape and thus to highlight the influence of crystal defects on the magnetism of Co{sub 80}Ni{sub 20} nanowires. A micromagnetic study, consistent with the experimental analyses, is also presented. The results discussed in this work clearly show that even if the morphological characteristics are conducive to a high coercive field, the presence of numerous stacking faults has the opposite effect and leads to materials with a significantly lower coercive field than expected, which is not suitable for permanent magnet applications. - Highlights: • Optimization of the nanowires magnetic properties for permanent magnet applications. • Magnetization reversal mechanism study as function of the shape, structural and chemical homogeneity. • Effect of stacking faults on the coercive

Reliability of Single Crystal Silver Nanowire-Based Systems: Stress Assisted Instabilities.

Science.gov (United States)

Ramachandramoorthy, Rajaprakash; Wang, Yanming; Aghaei, Amin; Richter, Gunther; Cai, Wei; Espinosa, Horacio D

2017-05-23

Time-dependent mechanical characterization of nanowires is critical to understand their long-term reliability in applications, such as flexible-electronics and touch screens. It is also of great importance to develop a theoretical framework for experimentation and analysis on the mechanics of nanowires under time-dependent loading conditions, such as stress-relaxation and fatigue. Here, we combine in situ scanning electron microscope (SEM)/transmission electron microscope (TEM) tests with atomistic and phase-field simulations to understand the deformation mechanisms of single crystal silver nanowires held under constant strain. We observe that the nanowires initially undergo stress-relaxation, where the stress reduces with time and saturates after some time period. The stress-relaxation process occurs due to the formation of few dislocations and stacking faults. Remarkably, after a few hours the nanowires rupture suddenly. The reason for this abrupt failure of the nanowire was identified as stress-assisted diffusion, using phase-field simulations. Under a large applied strain, diffusion leads to the amplification of nanowire surface perturbation at long wavelengths and the nanowire fails at the stress-concentrated thin cross-sectional regions. An analytical analysis on the competition between the elastic energy and the surface energy predicts a longer time to failure for thicker nanowires than thinner ones, consistent with our experimental observations. The measured time to failure of nanowires under cyclic loading conditions can also be explained in terms of this mechanism.

Growth and characterisation of group-III nitride-based nanowires for devices

Energy Technology Data Exchange (ETDEWEB)

Meijers, R J

2007-08-30

faults sometimes form at the base of the wires. Optical spectra also exhibit a band gap consistent with strain-free GaN in the upper part of the wires. For InN a band gap value of 0.7-0.8 eV has been determined at low temperatures. The doping concentration and the position of the Fermi-level in InN depend very much on the crystalline quality. In general the luminescence of GaN and InN improves with increased T{sub sub}. For GaN the defect-related peaks decrease and in InN the carrier concentration is reduced. Optical spectra confirm the effective incorporation of the dopant species in the nanowires despite a large nanowire surface and unfavourable growth conditions for doping, which are required for nitride nanowire growth. (orig.)

Multisensor system based on bisphthalocyanine nanowires for the detection of antioxidants

International Nuclear Information System (INIS)

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

2012-01-01

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

Effect of zinc doping on the bandgap and photoluminescence of Zn2+-doped TiO2 nanowires

Science.gov (United States)

Loan, Trinh Thi; Huong, Vu Hoang; Tham, Vu Thi; Long, Nguyen Ngoc

2018-03-01

This study was focused on the effect of Zn2+ dopant concentration on the absorption edge and photoluminescence of anatase TiO2 nanowires synthesized by hydrothermal technique. For the undoped anatase TiO2 nanowires, the indirect band gap of 3.26 eV and the direct band gap of 3.58 eV are assigned to the indirect Γ3 → X1b and direct X2b → X1b transitions, respectively. The Zn2+-doping makes the absorption edge of TiO2:Zn2+ nanowires shift towards the lower energy side (red shift). On the other hand, the replacing Ti4+ ions with Zn2+ ions creates oxygen vacancies (VO) and shallow defects associated with VO. Just these defects are responsible for the enhanced luminescence of Zn2+-doped TiO2 nanowires.

Effect of the nanowire diameter on the linearity of the response of GaN-based heterostructured nanowire photodetectors

Science.gov (United States)

Spies, Maria; Polaczyński, Jakub; Ajay, Akhil; Kalita, Dipankar; Luong, Minh Anh; Lähnemann, Jonas; Gayral, Bruno; den Hertog, Martien I.; Monroy, Eva

2018-06-01

Nanowire photodetectors are investigated because of their compatibility with flexible electronics, or for the implementation of on-chip optical interconnects. Such devices are characterized by ultrahigh photocurrent gain, but their photoresponse scales sublinearly with the optical power. Here, we present a study of single-nanowire photodetectors displaying a linear response to ultraviolet illumination. Their structure consists of a GaN nanowire incorporating an AlN/GaN/AlN heterostructure, which generates an internal electric field. The activity of the heterostructure is confirmed by the rectifying behavior of the current–voltage characteristics in the dark, as well as by the asymmetry of the photoresponse in magnitude and linearity. Under reverse bias (negative bias on the GaN cap segment), the detectors behave linearly with the impinging optical power when the nanowire diameter is below a certain threshold (≈80 nm), which corresponds to the total depletion of the nanowire stem due to the Fermi level pinning at the sidewalls. In the case of nanowires that are only partially depleted, their nonlinearity is explained by a nonlinear variation of the diameter of their central conducting channel under illumination.

Effects of quantum confinement and shape on band gap of core/shell quantum dots and nanowires

Science.gov (United States)

Gao, Faming

2011-05-01

A quantum confinement model for nanocrystals developed is extended to study for the optical gap shifts in core/shell quantum dots and nanowires. The chemical bond properties and gap shifts in the InP/ZnS, CdSe/CdS, CdSe/ZnS, and CdTe/ZnS core/shell quantum dots are calculated in detail. The calculated band gaps are in excellent agreement with experimental values. The effects of structural taping and twinning on quantum confinement of InP and Si nanowires are elucidated. It is found theoretically that a competition between the positive Kubo energy-gap shift and the negative surface energy shift plays the crucial role in the optical gaps of these nanosystems.

Diluted magnetic semiconductor nanowires exhibiting magnetoresistance

Science.gov (United States)

Yang, Peidong [El Cerrito, CA; Choi, Heonjin [Seoul, KR; Lee, Sangkwon [Daejeon, KR; He, Rongrui [Albany, CA; Zhang, Yanfeng [El Cerrito, CA; Kuykendal, Tevye [Berkeley, CA; Pauzauskie, Peter [Berkeley, CA

2011-08-23

A method for is disclosed for fabricating diluted magnetic semiconductor (DMS) nanowires by providing a catalyst-coated substrate and subjecting at least a portion of the substrate to a semiconductor, and dopant via chloride-based vapor transport to synthesize the nanowires. Using this novel chloride-based chemical vapor transport process, single crystalline diluted magnetic semiconductor nanowires Ga.sub.1-xMn.sub.xN (x=0.07) were synthesized. The nanowires, which have diameters of .about.10 nm to 100 nm and lengths of up to tens of micrometers, show ferromagnetism with Curie temperature above room temperature, and magnetoresistance up to 250 Kelvin.

Site-Specific Growth and in Situ Integration of Different Nanowire Material Networks on a Single Chip: Toward a Nanowire-Based Electronic Nose for Gas Detection.

Science.gov (United States)

Hrachowina, Lukas; Domènech-Gil, Guillem; Pardo, Antonio; Seifner, Michael S; Gràcia, Isabel; Cané, Carles; Romano-Rodríguez, Albert; Barth, Sven

2018-03-23

A new method for the site-selective synthesis of nanowires has been developed to enable material growth with defined morphology and, at the same time, different composition on the same chip surface. The chemical vapor deposition approach for the growth of these nanowire-based resistive devices using micromembranes can be easily modified and represents a simple, adjustable fabrication process for the direct integration of nanowire meshes in multifunctional devices. This proof-of-concept study includes the deposition of SnO 2 , WO 3 , and Ge nanowires on the same chip. The individual resistors exhibit adequate gas sensing responses toward changing gas concentrations of CO, NO 2 , and humidity diluted in synthetic air. The data have been processed by principal component analysis with cluster responses that can be easily separated, and thus, the devices described herein are in principle suitable for environmental monitoring.

Spectrally selective solar absorber with sharp and temperature dependent cut-off based on semiconductor nanowire arrays

Science.gov (United States)

Wang, Yang; Zhou, Lin; Zheng, Qinghui; Lu, Hong; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

2017-05-01

Spectrally selective absorbers (SSA) with high selectivity of absorption and sharp cut-off between high absorptivity and low emissivity are critical for efficient solar energy conversion. Here, we report the semiconductor nanowire enabled SSA with not only high absorption selectivity but also temperature dependent sharp absorption cut-off. By taking advantage of the temperature dependent bandgap of semiconductors, we systematically demonstrate that the absorption cut-off profile of the semiconductor-nanowire-based SSA can be flexibly tuned, which is quite different from most of the other SSA reported so far. As an example, silicon nanowire based selective absorbers are fabricated, with the measured absorption efficiency above (below) bandgap ˜97% (15%) combined with an extremely sharp absorption cut-off (transition region ˜200 nm), the sharpest SSA demonstrated so far. The demonstrated semiconductor-nanowire-based SSA can enable a high solar thermal efficiency of ≳86% under a wide range of operating conditions, which would be competitive candidates for the concentrated solar energy utilizations.

Photovoltaic and Impedance Properties of Hierarchical TiO2 Nanowire Based Quantum Dot Sensitized Solar Cell

Directory of Open Access Journals (Sweden)

Amanullah Fatehmulla

2015-01-01

Full Text Available Growth and characterization of TiO2 nanowire (NW assemblies on FTO glass using a typical hydrothermal synthesis have been reported. CdS quantum dots (QDs have been deposited on TiO2 nanowires by successive ion layer adsorption and reaction (SILAR method. FESEM image exhibits the flower-like hierarchical TiO2 bunch of nanowires. HRTEM image confirms the size of CdS QDs between 5 and 6 nm. XRD and absorption studies revealed proper growth of CdS quantum dots on TiO2 nanowires. At AM 1.5 illumination intensity, the solar cell, with the configuration FTO/TiO2-NW/CdS-QDs/Pt-FTO, displays a short circuit current (Jsc of 1.295 mA and an open circuit voltage (Voc of 0.38 V. The Voc and Jsc showed linear behavior at higher illumination intensities. The peak in power-voltage characteristics at various illuminations showed a shift towards higher Voc values. Capacitance-voltage (C-V, conductance-voltage (G-V, and series resistance-voltage (Rs-V measurements of the cell in the frequency ranging from 5 kHz to 5 MHz showed decreasing trend of capacitance with increase of frequency whereas increase in conductance and decrease in resistance have been noticed with increase of frequency. All the results including the individual behavior of the plots of capacitance, conductance, and series resistance as a function of bias voltage have been discussed.

Quantum optics with nanowires (Conference Presentation)

Science.gov (United States)

Zwiller, Val

2017-02-01

Nanowires offer new opportunities for nanoscale quantum optics; the quantum dot geometry in semiconducting nanowires as well as the material composition and environment can be engineered with unprecedented freedom to improve the light extraction efficiency. Quantum dots in nanowires are shown to be efficient single photon sources, in addition because of the very small fine structure splitting, we demonstrate the generation of entangled pairs of photons from a nanowire. By doping a nanowire and making ohmic contacts on both sides, a nanowire light emitting diode can be obtained with a single quantum dot as the active region. Under forward bias, this will act as an electrically pumped source of single photons. Under reverse bias, an avalanche effect can multiply photocurrent and enables the detection of single photons. Another type of nanowire under study in our group is superconducting nanowires for single photon detection, reaching efficiencies, time resolution and dark counts beyond currently available detectors. We will discuss our first attempts at combining semiconducting nanowire based single photon emitters and superconducting nanowire single photon detectors on a chip to realize integrated quantum circuits.

Preparation and characterization of titania based nanowires

International Nuclear Information System (INIS)

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

2007-01-01

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

Ultra compact triplexing filters based on SOI nanowire AWGs

Science.gov (United States)

Jiashun, Zhang; Junming, An; Lei, Zhao; Shijiao, Song; Liangliang, Wang; Jianguang, Li; Hongjie, Wang; Yuanda, Wu; Xiongwei, Hu

2011-04-01

An ultra compact triplexing filter was designed based on a silicon on insulator (SOI) nanowire arrayed waveguide grating (AWG) for fiber-to-the-home FTTH. The simulation results revealed that the design performed well in the sense of having a good triplexing function. The designed SOI nanowire AWGs were fabricated using ultraviolet lithography and induced coupler plasma etching. The experimental results showed that the crosstalk was less than -15 dB, and the 3 dB-bandwidth was 11.04 nm. The peak wavelength output from ports a, c, and b were 1455, 1510 and 1300 nm, respectively, which deviated from our original expectations. The deviation of the wavelength is mainly caused by 45 nm width deviation of the arrayed waveguides during the course of the fabrication process and partly caused by material dispersion.

Quantum Dot Sensitized Solar Cells Based on Ternary Metal Oxide Nanowires

Energy Technology Data Exchange (ETDEWEB)

Wang, Wenyong [Univ. of Wyoming, Laramie, WY (United States); Tang, Jinke [Univ. of Wyoming, Laramie, WY (United States); Dahnovsky, Yuri [Univ. of Wyoming, Laramie, WY (United States); Pikal, Jon M [Univ. of Wyoming, Laramie, WY (United States); Chien, TeYu [Univ. of Wyoming, Laramie, WY (United States)

2017-11-03

In Phase I of this project we investigate quantum dot sensitized solar cells (QDSSCs) based on ternary metal oxide nanowires and study the physical and chemical mechanisms that govern device operation. Our research has the following five objectives: (1) synthesis of ternary metal oxide nanowires, (2) synthesis of QDs and exploration of non-solution based QD deposition methods, (3) physical and electro-optical characterizations of fabricated solar devices, (4) device modeling and first-principle theoretical study of transport physics, and (5) investigation of long-term stability issues of QD sensitized solar cells. In Phase II of this project our first major research goal is to investigate magnetically doped quantum dots and related spin polarization effect, which could improve light absorption and suppress electron relaxation in the QDs. We will utilize both physical and chemical methods to synthesize these doped QDs. We will also study magnetically modified nanowires and introduce spin-polarized transport into QDSSCs, and inspect its impact on forward electron injection and back electron transfer processes. Our second goal is to study novel solid-state electrolytes for QDSSCs. Specifically, we will inspect a new type of polymer electrolytes based on a modified polysulfide redox couple, and examine the effect of their electrical properties on QDSSC performance. These solid-state electrolytes could also be used as filler materials for in situ sample fracturing in STM and enable cross-sectional interface examination of QD/nanowire structures. Our third research goal is to examine the interfacial properties such as energy level alignment at QD/nanowire interfaces using the newly developed Cross-sectional Scanning Tunneling Microscopy and Spectroscopy technique for non-cleavable materials. This technique allows a direct probing of band structures and alignment at device interfaces, which could generate important insight into the mechanisms that govern QDSSC operation

EDITORIAL: Nanowires for energy Nanowires for energy

Science.gov (United States)

LaPierre, Ray; Sunkara, Mahendra

2012-05-01

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

Flexible powder electroluminescent device on silver nanowire electrode

International Nuclear Information System (INIS)

Park, K.W.; Jeong, H.S.; Park, J.H.; Deressa, G.; Jeong, Y.T.; Lim, K.T.; Park, J.H.; Lee, S.H.; Kim, J.S.

2015-01-01

We have demonstrated the flexible AC powder electroluminescent device based on Ag nanowire electrode. The Ag nanowire electrode showed the nanowire morphology of 20 nm in diameter and 15 μm in length, the transmittance of 87%, and the sheet resistance of 50 Ω/sq, and the higher flexibility than the conventional ITO substrate. The electroluminescence spectra of the Ag nanowire-based device in all frequency and voltage ranges were almost similar with the ITO-based device. In comparison with the ITO-based device, the luminous efficiency of the Ag nanowire-based device was almost same as 1.53 lm/W. - Highlights: • Flexibility of Ag NW substrate was higher than ITO substrate. • EL intensity of Ag NW-based EL device was almost similar with ITO-based EL device. • Charge density and turn-on voltage of Ag NW-based EL device were a little larger than ITO-based EL device

Flexible powder electroluminescent device on silver nanowire electrode

Energy Technology Data Exchange (ETDEWEB)

Park, K.W.; Jeong, H.S.; Park, J.H.; Deressa, G.; Jeong, Y.T.; Lim, K.T. [Department of Display Science and Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Park, J.H. [AIDEN company, Cheongju-si 361-911 (Korea, Republic of); Lee, S.H. [R& D Business Lab, Hyosung Corporation, Anyang 431-080 (Korea, Republic of); Kim, J.S., E-mail: jsukim@pknu.ac.kr [Department of Display Science and Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2015-09-15

We have demonstrated the flexible AC powder electroluminescent device based on Ag nanowire electrode. The Ag nanowire electrode showed the nanowire morphology of 20 nm in diameter and 15 μm in length, the transmittance of 87%, and the sheet resistance of 50 Ω/sq, and the higher flexibility than the conventional ITO substrate. The electroluminescence spectra of the Ag nanowire-based device in all frequency and voltage ranges were almost similar with the ITO-based device. In comparison with the ITO-based device, the luminous efficiency of the Ag nanowire-based device was almost same as 1.53 lm/W. - Highlights: • Flexibility of Ag NW substrate was higher than ITO substrate. • EL intensity of Ag NW-based EL device was almost similar with ITO-based EL device. • Charge density and turn-on voltage of Ag NW-based EL device were a little larger than ITO-based EL device.

Nanowire sensors and arrays for chemical/biomolecule detection

Science.gov (United States)

Yun, Minhee; Lee, Choonsup; Vasquez, Richard P.; Ramanathan, K.; Bangar, M. A.; Chen, W.; Mulchandan, A.; Myung, N. V.

2005-01-01

We report electrochemical growth of single nanowire based sensors using e-beam patterned electrolyte channels, potentially enabling the controlled fabrication of individually addressable high density arrays. The electrodeposition technique results in nanowires with controlled dimensions, positions, alignments, and chemical compositions. Using this technique, we have fabricated single palladium nanowires with diameters ranging between 75 nm and 300 nm and conducting polymer nanowires (polypyrrole and polyaniline) with diameters between 100 nm and 200 nm. Using these single nanowires, we have successfully demonstrated gas sensing with Pd nanowires and pH sensing with polypirrole nanowires.

Nanowire-decorated microscale metallic electrodes

DEFF Research Database (Denmark)

Vlad, A.; Mátéfi-Tempfli, M.; Antohe, V.A.

2008-01-01

The fabrication of metallic nanowire patterns within anodic alumina oxide (AAO) membranes on top of continuous conducting substrates are discussed. The fabrication protocol is based on the realization of nanowire patterns using supported nanoporous alumina templates (SNAT) prepared on top...... of lithographically defined metallic microelectrodes. The anodization of the aluminum permits electroplating only on top of the metallic electrodes, leading to the nanowire patterns having the same shape as the underlying metallic tracks. The variation in the fabricated structures between the patterned and non......-patterned substrates can be interpreted in terms of different behavior during anodization. The improved quality of fabricated nanowire patterns is clearly demonstrated by the SEM imaging and the uniform growth of nanowires inside the alumina template is observed without any significant height variation....

Quantum dot-based local field imaging reveals plasmon-based interferometric logic in silver nanowire networks.

Science.gov (United States)

Wei, Hong; Li, Zhipeng; Tian, Xiaorui; Wang, Zhuoxian; Cong, Fengzi; Liu, Ning; Zhang, Shunping; Nordlander, Peter; Halas, Naomi J; Xu, Hongxing

2011-02-09

We show that the local electric field distribution of propagating plasmons along silver nanowires can be imaged by coating the nanowires with a layer of quantum dots, held off the surface of the nanowire by a nanoscale dielectric spacer layer. In simple networks of silver nanowires with two optical inputs, control of the optical polarization and phase of the input fields directs the guided waves to a specific nanowire output. The QD-luminescent images of these structures reveal that a complete family of phase-dependent, interferometric logic functions can be performed on these simple networks. These results show the potential for plasmonic waveguides to support compact interferometric logic operations.

Optoelectrical modeling of solar cells based on c-Si/a-Si:H nanowire array: focus on the electrical transport in between the nanowires

Science.gov (United States)

Levtchenko, Alexandra; Le Gall, Sylvain; Lachaume, Raphaël; Michallon, Jérôme; Collin, Stéphane; Alvarez, José; Djebbour, Zakaria; Kleider, Jean-Paul

2018-06-01

By coupling optical and electrical modeling, we have investigated the photovoltaic performances of p-i-n radial nanowires array based on crystalline p-type silicon (c-Si) core/hydrogenated amorphous silicon (a-Si:H) shell. By varying either the doping concentration of the c-Si core, or back contact work function we can separate and highlight the contribution to the cell’s performance of the nanowires themselves (the radial cell) from the interspace between the nanowires (the planar cell). We show that the build-in potential (V bi) in the radial and planar cells strongly depends on the doping of c-Si core and the work function of the back contact respectively. Consequently, the solar cell’s performance is degraded if either the doping concentration of the c-Si core, or/and the work function of the back contact is too low. By inserting a thin (p) a-Si:H layer between both core/absorber and back contact/absorber, the performance of the solar cell can be improved by partly fixing the V bi at both interfaces due to strong electrostatic screening effect. Depositing such a buffer layer playing the role of an electrostatic screen for charge carriers is a suggested way of enhancing the performance of solar cells based on radial p-i-n or n-i-p nanowire array.

Single memory with multiple shift register functionality

NARCIS (Netherlands)

2010-01-01

The present invention relates to a memory device comprising a memory (EM) having at least two predetermined register memory sections addressable by respective address ranges AS1-ASz) and at least one access port (P1-PZ) for providing access to said memory (EM). Furthermore, access control means (A)

Temperature Dependence of the Moessbauer Effect on Prussian Blue Nanowires

Energy Technology Data Exchange (ETDEWEB)

Zhou Pingheng; Xue Desheng; Luo Haiqing; Shi Huigang [Lanzhou University, Key Lab for Magnetism and Magnetic Materials of MOE (China)

2002-09-15

Highly ordered Prussian blue nanowires with diameter of about 50 nm and length up to 4 {mu}m have been fabricated by an electrodepositing technology with two-step anodizing anodic aluminum oxide films. The Moessbauer spectra taken between 15 and 300 K indicate that the hyperfine parameters decrease as the temperature increases. The temperature dependence of the quadrupole splitting, the isomer shift and the spectra area are discussed. A decrease of Debye temperature for Prussian blue nanowires was found with respect to that of Prussian blue bulk.

Sensing Responses Based on Transfer Characteristics of InAs Nanowire Field-Effect Transistors

Science.gov (United States)

Savelyev, Igor; Blumin, Marina; Wang, Shiliang; Ruda, Harry E.

2017-01-01

Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that can be used in applications such as point-of-care testing for patients diagnosed with chronic diseases. Here, we propose devices based on a parallel configuration of InAs nanowires and investigate sensor responses from measurements of conductance over time and FET characteristics. The devices were tested in controlled concentrations of vapour containing acetic acid, 2-butanone and methanol. After adsorption of analyte molecules, trends in the transient current and transfer curves are correlated with the nature of the surface interaction. Specifically, we observed proportionality between acetic acid concentration and relative conductance change, off current and surface charge density extracted from subthreshold behaviour. We suggest the origin of the sensing response to acetic acid as a two-part, reversible acid-base and redox reaction between acetic acid, InAs and its native oxide that forms slow, donor-like states at the nanowire surface. We further describe a simple model that is able to distinguish the occurrence of physical versus chemical adsorption by comparing the values of the extracted surface charge density. These studies demonstrate that InAs nanowires can produce a multitude of sensor responses for the purpose of developing next generation, multi-dimensional sensor applications. PMID:28714903

Understanding InP Nanowire Array Solar Cell Performance by Nanoprobe-Enabled Single Nanowire Measurements.

Science.gov (United States)

Otnes, Gaute; Barrigón, Enrique; Sundvall, Christian; Svensson, K Erik; Heurlin, Magnus; Siefer, Gerald; Samuelson, Lars; Åberg, Ingvar; Borgström, Magnus T

2018-05-09

III-V solar cells in the nanowire geometry might hold significant synthesis-cost and device-design advantages as compared to thin films and have shown impressive performance improvements in recent years. To continue this development there is a need for characterization techniques giving quick and reliable feedback for growth development. Further, characterization techniques which can improve understanding of the link between nanowire growth conditions, subsequent processing, and solar cell performance are desired. Here, we present the use of a nanoprobe system inside a scanning electron microscope to efficiently contact single nanowires and characterize them in terms of key parameters for solar cell performance. Specifically, we study single as-grown InP nanowires and use electron beam induced current characterization to understand the charge carrier collection properties, and dark current-voltage characteristics to understand the diode recombination characteristics. By correlating the single nanowire measurements to performance of fully processed nanowire array solar cells, we identify how the performance limiting parameters are related to growth and/or processing conditions. We use this understanding to achieve a more than 7-fold improvement in efficiency of our InP nanowire solar cells, grown from a different seed particle pattern than previously reported from our group. The best cell shows a certified efficiency of 15.0%; the highest reported value for a bottom-up synthesized InP nanowire solar cell. We believe the presented approach have significant potential to speed-up the development of nanowire solar cells, as well as other nanowire-based electronic/optoelectronic devices.

Probe based manipulation and assembly of nanowires into organized mesostructures

Science.gov (United States)

Reynolds, K.; Komulainen, J.; Kivijakola, J.; Lovera, P.; Iacopino, D.; Pudas, M.; Vähäkangas, J.; Röning, J.; Redmond, G.

2008-12-01

A convenient approach to patterning inorganic and organic nanowires using a novel probe manipulator is presented. The system utilizes an electrochemically etched tungsten wire probe mounted onto a 3D actuator that is directed by a 3D controller. When it is engaged by the user, the movement of the probe and the forces experienced by the tip are simultaneously reported in real time. Platinum nanowires are manipulated into organized mesostructures on silicon chip substrates. In particular, individual nanowires are systematically removed from aggregates, transferred to a chosen location, and manipulated into complex structures in which selected wires occupy specific positions with defined orientations. Rapid prototyping of complex mesostructures, by pushing, rotating and bending conjugated polymer, i.e., polyfluorene, nanowires into various configurations, is also achieved. By exploiting the strong internal axial alignment of polymer chains within the polyfluorene nanowires, mesostructures tailored to exhibit distinctly anisotropic optical properties, such as birefringence and photoluminescence dichroism, are successfully assembled on fused silica substrates.

Probe based manipulation and assembly of nanowires into organized mesostructures

International Nuclear Information System (INIS)

Reynolds, K; Lovera, P; Iacopino, D; Redmond, G; Komulainen, J; Pudas, M; Vaehaekangas, J; Kivijakola, J; Roening, J

2008-01-01

A convenient approach to patterning inorganic and organic nanowires using a novel probe manipulator is presented. The system utilizes an electrochemically etched tungsten wire probe mounted onto a 3D actuator that is directed by a 3D controller. When it is engaged by the user, the movement of the probe and the forces experienced by the tip are simultaneously reported in real time. Platinum nanowires are manipulated into organized mesostructures on silicon chip substrates. In particular, individual nanowires are systematically removed from aggregates, transferred to a chosen location, and manipulated into complex structures in which selected wires occupy specific positions with defined orientations. Rapid prototyping of complex mesostructures, by pushing, rotating and bending conjugated polymer, i.e., polyfluorene, nanowires into various configurations, is also achieved. By exploiting the strong internal axial alignment of polymer chains within the polyfluorene nanowires, mesostructures tailored to exhibit distinctly anisotropic optical properties, such as birefringence and photoluminescence dichroism, are successfully assembled on fused silica substrates.

Angular dependence of coercivity with temperature in Co-based nanowires

Energy Technology Data Exchange (ETDEWEB)

Bran, C., E-mail: cristina.bran@icmm.csic.es [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain); Espejo, A.P. [Departamento de Física, Universidad de Santiago de Chile (USACH) and Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avenida Ecuador 3493, 9170124 Santiago (Chile); Palmero, E.M. [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain); Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH) and Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avenida Ecuador 3493, 9170124 Santiago (Chile); Vázquez, M. [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain)

2015-12-15

The magnetic behavior of arrays of Co and CoFe nanowire arrays has been measured in the temperature range between 100 and 300 K. We have paid particular attention to the angular dependence of magnetic properties on the applied magnetic field orientation. The experimental angular dependence of coercivity has been modeled according to micromagnetic analytical calculations, and we found that the propagation of a transversal domain wall mode gives the best fitting with experimental observations. That reversal mode holds in the whole measuring temperature range, for nanowires with different diameters and crystalline structure. Moreover, the quantitative strength of the magnetocrystalline anisotropy and its magnetization easy axis are determined to depend on the crystalline structure and nanowires diameter. The evolution of the magnetocrystalline anisotropy with temperature for nanowires with different composition gives rise to an opposite evolution of coercivity with increasing temperature: it decreases for CoFe while it increases for Co nanowire arrays.

Register-based statistics statistical methods for administrative data

CERN Document Server

Wallgren, Anders

2014-01-01

This book provides a comprehensive and up to date treatment of  theory and practical implementation in Register-based statistics. It begins by defining the area, before explaining how to structure such systems, as well as detailing alternative approaches. It explains how to create statistical registers, how to implement quality assurance, and the use of IT systems for register-based statistics. Further to this, clear details are given about the practicalities of implementing such statistical methods, such as protection of privacy and the coordination and coherence of such an undertaking. Thi

Electrically Injected UV-Visible Nanowire Lasers

Energy Technology Data Exchange (ETDEWEB)

Wang, George T.; Li, Changyi; Li, Qiming; Liu, Sheng; Wright, Jeremy Benjamin; Brener, Igal; Luk, Ting -Shan; Chow, Weng W.; Leung, Benjamin; Figiel, Jeffrey J.; Koleske, Daniel D.; Lu, Tzu-Ming

2015-09-01

There is strong interest in minimizing the volume of lasers to enable ultracompact, low-power, coherent light sources. Nanowires represent an ideal candidate for such nanolasers as stand-alone optical cavities and gain media, and optically pumped nanowire lasing has been demonstrated in several semiconductor systems. Electrically injected nanowire lasers are needed to realize actual working devices but have been elusive due to limitations of current methods to address the requirement for nanowire device heterostructures with high material quality, controlled doping and geometry, low optical loss, and efficient carrier injection. In this project we proposed to demonstrate electrically injected single nanowire lasers emitting in the important UV to visible wavelengths. Our approach to simultaneously address these challenges is based on high quality III-nitride nanowire device heterostructures with precisely controlled geometries and strong gain and mode confinement to minimize lasing thresholds, enabled by a unique top-down nanowire fabrication technique.

Suspended tungsten-based nanowires with enhanced mechanical properties grown by focused ion beam induced deposition

Science.gov (United States)

Córdoba, Rosa; Lorenzoni, Matteo; Pablo-Navarro, Javier; Magén, César; Pérez-Murano, Francesc; María De Teresa, José

2017-11-01

The implementation of three-dimensional (3D) nano-objects as building blocks for the next generation of electro-mechanical, memory and sensing nano-devices is at the forefront of technology. The direct writing of functional 3D nanostructures is made feasible by using a method based on focused ion beam induced deposition (FIBID). We use this technique to grow horizontally suspended tungsten nanowires and then study their nano-mechanical properties by three-point bending method with atomic force microscopy. These measurements reveal that these nanowires exhibit a yield strength up to 12 times higher than that of the bulk tungsten, and near the theoretical value of 0.1 times the Young’s modulus (E). We find a size dependence of E that is adequately described by a core-shell model, which has been confirmed by transmission electron microscopy and compositional analysis at the nanoscale. Additionally, we show that experimental resonance frequencies of suspended nanowires (in the MHz range) are in good agreement with theoretical values. These extraordinary mechanical properties are key to designing electro-mechanically robust nanodevices based on FIBID tungsten nanowires.

Ultra compact triplexing filters based on SOI nanowire AWGs

Energy Technology Data Exchange (ETDEWEB)

Zhang Jiashun; An Junming; Zhao Lei; Song Shijiao; Wang Liangliang; Li Jianguang; Wang Hongjie; Wu Yuanda; Hu Xiongwei, E-mail: junming@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2011-04-15

An ultra compact triplexing filter was designed based on a silicon on insulator (SOI) nanowire arrayed waveguide grating (AWG) for fiber-to-the-home FTTH. The simulation results revealed that the design performed well in the sense of having a good triplexing function. The designed SOI nanowire AWGs were fabricated using ultraviolet lithography and induced coupler plasma etching. The experimental results showed that the crosstalk was less than -15 dB, and the 3 dB-bandwidth was 11.04 nm. The peak wavelength output from ports a, c, and b were 1455, 1510 and 1300 nm, respectively, which deviated from our original expectations. The deviation of the wavelength is mainly caused by 45 nm width deviation of the arrayed waveguides during the course of the fabrication process and partly caused by material dispersion. (semiconductor devices)

Ultra compact triplexing filters based on SOI nanowire AWGs

International Nuclear Information System (INIS)

Zhang Jiashun; An Junming; Zhao Lei; Song Shijiao; Wang Liangliang; Li Jianguang; Wang Hongjie; Wu Yuanda; Hu Xiongwei

2011-01-01

An ultra compact triplexing filter was designed based on a silicon on insulator (SOI) nanowire arrayed waveguide grating (AWG) for fiber-to-the-home FTTH. The simulation results revealed that the design performed well in the sense of having a good triplexing function. The designed SOI nanowire AWGs were fabricated using ultraviolet lithography and induced coupler plasma etching. The experimental results showed that the crosstalk was less than -15 dB, and the 3 dB-bandwidth was 11.04 nm. The peak wavelength output from ports a, c, and b were 1455, 1510 and 1300 nm, respectively, which deviated from our original expectations. The deviation of the wavelength is mainly caused by 45 nm width deviation of the arrayed waveguides during the course of the fabrication process and partly caused by material dispersion. (semiconductor devices)

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.

Design of Indium Arsenide nanowire sensors for pH and biological sensing and low temperature transport through p-doped Indium Arsenide nanowires

DEFF Research Database (Denmark)

Upadhyay, Shivendra

With the goal of real time electrical detection of chemical and biological species, nanowires have shown great promise with high sensitivity due to their large surface to volume ratio. While the focus of such electrical detection has shifted to one dimensional semiconductor nanostuctures, Silicon...

Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles

Science.gov (United States)

Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

2018-06-01

Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

Register-based studies of cardiovascular disease

DEFF Research Database (Denmark)

Abildstrøm, Steen Z; Torp-Pedersen, Christian; Madsen, Mette

2011-01-01

Introduction: The use of the unique personal identification number in the Nordic database systems enables the researchers to link the registers at the individual level. The registers can be used for both defining specific patient populations and to identify later events during follow-up. This rev...... the hospitalisation rate and treatment of cardiovascular disease. The risk of unmeasured factors affecting the results calls for cautious interpretation of the results.......-up. This review gives three examples within cardiovascular epidemiology to illustrate the use of the national administrative registers available to all researchers upon request. Research topics: The hospitalisation rate of acute myocardial infarction (AMI) was expected to be increased and case-fatality rate......-based treatment increased significantly over time and adherence to treatment was high. Finally, use of specific nonsteroidal antiinflammatory drugs by healthy subjects was associated with a dose-dependent increase in cardiovascular risk. CONCLUSION: The nationwide registers have proven very useful in monitoring...

Identifying victims of violence using register-based data

DEFF Research Database (Denmark)

Kruse, Marie; Sørensen, Jan; Brønnum-Hansen, Henrik

2010-01-01

AIMS: The aim of this study was twofold. Firstly we identified victims of violence in national registers and discussed strengths and weaknesses of this approach. Secondly we assessed the magnitude of violence and the characteristics of the victims using register-based data. METHODS: We used three...... nationwide registers to identify victims of violence: The National Patient Register, the Victim Statistics, and the Causes of Death Register. We merged these data and assessed the degree of overlap between data sources. We identified a reference population by selecting all individuals in Denmark over 15....... RESULTS: In 2006, 22,000 individuals were registered as having been exposed to violence. About 70% of these victims were men. Most victims were identified from emergency room contacts and police records, and few from the Causes of Death Register. There was some overlap between the two large data sources...

Platinum boride nanowires: Synthesis and characterization

International Nuclear Information System (INIS)

Ding Zhanhui; Qiu Lixia; Zhang Jian; Yao Bin; Cui Tian; Guan Weiming; Zheng Weitao; Wang Wenquan; Zhao Xudong; Liu Xiaoyang

2012-01-01

Highlights: ► Platinum boride nanowires have been synthesized via the direct current arc discharge method. ► XRD, TEM and SAED indicate that the nanowires are single-crystal PtB. ► Two broad photoluminescence emission peaks at about 586 nm and 626 nm have been observed in the PL spectroscopy of PtB nanowires. - Abstract: Platinum boride (PtB) nanowires have been successfully fabricated with direct current arc discharge method using a milled mixture of platinum (Pt) and boron nitride (BN) powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the compositions, morphology, and structures of the samples. The results show that PtB nanowires are 30–50 nm thick and 20–30 μm long. TEM and selected area electron diffraction (SAED) patterns identify that the PtB nanowires are single-crystalline in nature. A growth mechanism based on vapor–liquid–solid (VLS) process is proposed for the formation of nanowires.

Resistance Fluctuations in GaAs Nanowire Grids

Directory of Open Access Journals (Sweden)

Ivan Marasović

2014-01-01

Full Text Available We present a numerical study on resistance fluctuations in a series of nanowire-based grids. Each grid is made of GaAs nanowires arranged in parallel with metallic contacts crossing all nanowires perpendicularly. Electrical properties of GaAs nanowires known from previous experimental research are used as input parameters in the simulation procedure. Due to the nonhomogeneous doping, the resistivity changes along nanowire. Allowing two possible nanowire orientations (“upwards” or “downwards”, the resulting grid is partially disordered in vertical direction which causes resistance fluctuations. The system is modeled using a two-dimensional random resistor network. Transfer-matrix computation algorithm is used to calculate the total network resistance. It is found that probability density function (PDF of resistance fluctuations for a series of nanowire grids changes from Gaussian behavior towards the Bramwell-Holdsworth-Pinton distribution when both nanowire orientations are equally represented in the grid.

Design and Characterisation of III-V Semiconductor Nanowire Lasers

Science.gov (United States)

Saxena, Dhruv

The development of small, power-efficient lasers underpins many of the technologies that we utilise today. Semiconductor nanowires are promising for miniaturising lasers to even smaller dimensions. III-V semiconductors, such as Gallium Arsenide (GaAs) and Indium Phosphide (InP), are the most widely used materials for optoelectronic devices and so the development of nanowire lasers based on these materials is expected to have technologically significant outcomes. This PhD dissertation presents a comprehensive study of the design of III-V semiconductor nanowire lasers, with bulk and quantum confined active regions. Based on the design, various III-V semiconductor nanowire lasers are demonstrated, namely, GaAs nanowire lasers, GaAs/AlGaAs multi-quantum well (MQW) nanowire lasers and InP nanowire lasers. These nanowire lasers are shown to operate at room temperature, have low thresholds, and lase from different transverse modes. The structural and optoelectronic quality of nanowire lasers are characterised via electron microscopy and photoluminescence spectroscopic techniques. Lasing is characterised in all these devices by optical pumping. The lasing characteristics are analysed by rate equation modelling and the lasing mode(s) in these devices is characterised by threshold gain modelling, polarisation measurements and Fourier plane imaging. Firstly, GaAs nanowire lasers that operate at room temperature are demonstrated. This is achieved by determining the optimal nanowire diameter to reduce threshold gain and by passivating nanowires to improve their quantum efficiency (QE). High-quality surface passivated GaAs nanowires of suitable diameters are grown. The growth procedure is tailored to improve both QE and structural uniformity of nanowires. Room-temperature lasing is demonstrated from individual nanowires and lasing is characterised to be from TM01 mode by threshold gain modelling. To lower threshold even further, nanowire lasers with GaAs/AlGaAs coaxial multi

Optical emission of InAs nanowires

International Nuclear Information System (INIS)

Möller, M; De Lima Jr, M M; Cantarero, A; Chiaramonte, T; Cotta, M A; Iikawa, F

2012-01-01

Wurtzite InAs nanowire samples grown by chemical beam epitaxy have been analyzed by photoluminescence spectroscopy. The nanowires exhibit two main optical emission bands at low temperatures. They are attributed to the recombination of carriers in quantum well structures, formed by zincblende–wurtzite alternating layers, and to the donor–acceptor pair. The blue-shift observed in the former emission band when the excitation power is increased is in good agreement with the type-II band alignment between the wurtzite and zincblende sections predicted by previous theoretical works. When increasing the temperature and the excitation power successively, an additional band attributed to the band-to-band recombination from wurtzite InAs appears. We estimated a lower bound for the wurtzite band gap energy of approximately 0.46 eV at low temperature. (paper)

Optical emission of InAs nanowires

Science.gov (United States)

Möller, M.; de Lima, M. M., Jr.; Cantarero, A.; Chiaramonte, T.; Cotta, M. A.; Iikawa, F.

2012-09-01

Wurtzite InAs nanowire samples grown by chemical beam epitaxy have been analyzed by photoluminescence spectroscopy. The nanowires exhibit two main optical emission bands at low temperatures. They are attributed to the recombination of carriers in quantum well structures, formed by zincblende-wurtzite alternating layers, and to the donor-acceptor pair. The blue-shift observed in the former emission band when the excitation power is increased is in good agreement with the type-II band alignment between the wurtzite and zincblende sections predicted by previous theoretical works. When increasing the temperature and the excitation power successively, an additional band attributed to the band-to-band recombination from wurtzite InAs appears. We estimated a lower bound for the wurtzite band gap energy of approximately 0.46 eV at low temperature.

Broadband Polarization-Insensitive Wavelength Conversion Based on Non-Degenerate Four-Wave Mixing in a Silicon Nanowire

DEFF Research Database (Denmark)

Pu, Minhao; Hu, Hao; Ji, Hua

2012-01-01

We experimentally demonstrate broadband polarization-insensitive one-to-two wavelength conversion of a 10-Gb/s DPSK data signal based on non-degenerate four-wave mixing in a silicon nanowire with bit-error rate measurements.......We experimentally demonstrate broadband polarization-insensitive one-to-two wavelength conversion of a 10-Gb/s DPSK data signal based on non-degenerate four-wave mixing in a silicon nanowire with bit-error rate measurements....

Solution-processed core-shell nanowires for efficient photovoltaic cells.

Science.gov (United States)

Tang, Jinyao; Huo, Ziyang; Brittman, Sarah; Gao, Hanwei; Yang, Peidong

2011-08-21

Semiconductor nanowires are promising for photovoltaic applications, but, so far, nanowire-based solar cells have had lower efficiencies than planar cells made from the same materials, even allowing for the generally lower light absorption of nanowires. It is not clear, therefore, if the benefits of the nanowire structure, including better charge collection and transport and the possibility of enhanced absorption through light trapping, can outweigh the reductions in performance caused by recombination at the surface of the nanowires and at p-n junctions. Here, we fabricate core-shell nanowire solar cells with open-circuit voltage and fill factor values superior to those reported for equivalent planar cells, and an energy conversion efficiency of ∼5.4%, which is comparable to that of equivalent planar cells despite low light absorption levels. The device is made using a low-temperature solution-based cation exchange reaction that creates a heteroepitaxial junction between a single-crystalline CdS core and single-crystalline Cu2S shell. We integrate multiple cells on single nanowires in both series and parallel configurations for high output voltages and currents, respectively. The ability to produce efficient nanowire-based solar cells with a solution-based process and Earth-abundant elements could significantly reduce fabrication costs relative to existing high-temperature bulk material approaches.

Rapid determination of nanowires electrical properties using a dielectrophoresis-well based system

Science.gov (United States)

Constantinou, Marios; Hoettges, Kai F.; Krylyuk, Sergiy; Katz, Michael B.; Davydov, Albert; Rigas, Grigorios-Panagiotis; Stolojan, Vlad; Hughes, Michael P.; Shkunov, Maxim

2017-03-01

The use of high quality semiconducting nanomaterials for advanced device applications has been hampered by the unavoidable growth variability of electrical properties of one-dimensional nanomaterials, such as nanowires and nanotubes, thus highlighting the need for the characterization of efficient semiconducting nanomaterials. In this study, we demonstrate a low-cost, industrially scalable dielectrophoretic (DEP) nanowire assembly method for the rapid analysis of the electrical properties of inorganic single crystalline nanowires, by identifying key features in the DEP frequency response spectrum from 1 kHz to 20 MHz in just 60 s. Nanowires dispersed in anisole were characterized using a three-dimensional DEP chip (3DEP), and the resultant spectrum demonstrated a sharp change in nanowire response to DEP signal in 1-20 MHz frequency range. The 3DEP analysis, directly confirmed by field-effect transistor data, indicates that nanowires of higher quality are collected at high DEP signal frequency range above 10 MHz, whereas lower quality nanowires, with two orders of magnitude lower current per nanowire, are collected at lower DEP signal frequencies. These results show that the 3DEP platform can be used as a very efficient characterization tool of the electrical properties of rod-shaped nanoparticles to enable dielectrophoretic selective deposition of nanomaterials with superior conductivity properties.

Theoretical approach to the phonon modes and specific heat of germanium nanowires

Energy Technology Data Exchange (ETDEWEB)

Trejo, A.; López-Palacios, L.; Vázquez-Medina, R.; Cruz-Irisson, M., E-mail: irisson@ipn.mx

2014-11-15

The phonon modes and specific heat of Ge nanowires were computed using a first principles density functional theory scheme with a generalized gradient approximation and finite-displacement supercell algorithms. The nanowires were modeled in three different directions: [001], [111], and [110], using the supercell technique. All surface dangling bonds were saturated with Hydrogen atoms. The results show that the specific heat of the GeNWs at room temperature increases as the nanowire diameter decreases, regardless the orientation due to the phonon confinement and surface passivation. Also the phonon confinement effects could be observed since the highest optical phonon modes in the Ge vibration interval shifted to a lower frequency compared to their bulk counterparts.

Silicon nanowires nanogenerator based on the piezoelectricity of alpha-quartz.

Science.gov (United States)

Yin, Kui; Lin, Haiyang; Cai, Qian; Zhao, Yi; Lee, Shuit-Tong; Hu, Fei; Shao, Mingwang

2013-12-21

Silicon nanowires are important semiconductor with core/shell structure. In this work, the piezoelectric material alpha-quartz was grown in the interface of silicon nanowires by thermal treatment at 600 °C for 0.5 h. These nanowires were employed as starting materials to fabricate piezoelectric nanogenerators, which could convert kinetic energy into electrical one, exhibiting an output voltage of 36.5 V and a response current of 1.4 μA under a free-falling object of 300 g at a height of 30 cm.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-10-01

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

Uniaxial Magnetization Performance of Textured Fe Nanowire Arrays Electrodeposited by a Pulsed Potential Deposition Technique

Science.gov (United States)

Neetzel, C.; Ohgai, T.; Yanai, T.; Nakano, M.; Fukunaga, H.

2017-11-01

Textured ferromagnetic Fe nanowire arrays were electrodeposited using a rectangular-pulsed potential deposition technique into anodized aluminum oxide nanochannels. During the electrodeposition of Fe nanowire arrays at a cathodic potential of - 1.2 V, the growth rate of the nanowires was ca. 200 nm s-1. The aspect ratio of Fe nanowires with a diameter of 30 ± 5 nm reached ca. 2000. The long axis of Fe nanowires corresponded with the direction when a large overpotential during the on-time pulse was applied, whereas it orientated to the direction under the potentiostatic condition with a small overpotential. By shifting the on-time cathode potential up to - 1.8 V, the texture coefficient for the (200) plane, TC200, reached up to 1.94. Perpendicular magnetization performance was observed in Fe nanowire arrays. With increasing TC200, the squareness of Fe nanowire arrays increased up to 0.95 with the coercivity maintained at 1.4 kOe at room temperature. This research result has opened a novel possibility of Fe nanowire arrays that can be applied for a new permanent magnetic material without rare-earth metals.

Formation of ultralong copper nanowires by hydrothermal growth for transparent conducting applications

Science.gov (United States)

Balela, Mary Donnabelle L.; Tan, Michael

2017-07-01

Transparent conducting electrodes are key components of optoelectronic devices, such as touch screens, organic light emitting diodes (OLEDs) and solar cells. Recent market surveys have shown that the demands for these devices are rapidly growing at a tremendous rate. Semiconducting oxides, in particular indium tin oxide (ITO) are the material of choice for transparent conducting electrodes. However, these conventional oxides are typically brittle, which limits their applicability in flexible electronics. Metal nanowires, e.g. copper (Cu) nanowires, are considered as the best candidate as substitute for ITO due to their excellent mechanical and electrical properties. In this paper, ultralong copper (Cu) nanowires with were successfully prepared by hydrothermal growth at 50-80°C for 1 h. Ethylenediamine was employed as the structure-directing agents, while hydrazine was used as the reductant. In situ mixed potential measurement was also carried out to monitor Cu deposition. Higher temperature shifted the mixed potential negatively, leading to thicker Cu nanowires. Transparent conducting electrode, with a sheet resistance of 197 Ω sq-1 at an optical transmittance of around 61 %, was fabricated with the Cu nanowire ink.

Mechanical behavior enhancement of ZnO nanowire by embedding different nanowires

Directory of Open Access Journals (Sweden)

Ali Vazinishayan

2018-06-01

Full Text Available In this work, we employed commercial finite element modeling (FEM software package ABAQUS to analyze mechanical properties of ZnO nanowire before and after embedding with different kinds of nanowires, having different materials and cross-section models such as Au (circular, Ag (pentagonal and Si (rectangular using three point bending technique. The length and diameter of the ZnO nanowire were measured to be 12,280 nm and 103.2 nm, respectively. In addition, Au, Ag and Si nanowires were considered to have the length of 12,280 nm and the diameter of 27 nm. It was found that after embedding Si nanowire with rectangular cross-section into the ZnO nanowire, the distribution of Von Misses stresses criterion, displacement and strain were decreased than the other nanowires embedded. The highest stiffness, the elastic deformation and the high strength against brittle failure have been made by Si nanowire comparison to the Au and Ag nanowires, respectively. Keywords: Nanowires, Material effects, Mechanical properties, Brittle failure

A room temperature light source based on silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

Lo Faro, M.J. [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy); MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); D' Andrea, C. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Messina, E.; Fazio, B. [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy); Musumeci, P. [Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); Franzò, G. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Gucciardi, P.G.; Vasi, C. [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy); Priolo, F. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); Scuola Superiore di Catania, Via Valdisavoia 9, 95123 Catania (Italy); Iacona, F. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Irrera, A., E-mail: irrera@me.cnr.it [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy)

2016-08-31

We synthesized ultrathin Si nanowires (NWs) by metal assisted chemical wet etching, using a very thin discontinuous Au layer as precursor for the process. A bright room temperature emission in the visible range due to electron–hole recombination in quantum confined Si NWs is reported. A single walled carbon nanotube (CNT) suspension was prepared and dispersed in Si NW samples. The hybrid Si NW/CNT system exhibits a double emission at room temperature, both in the visible (due to Si NWs) and the IR (due to CNTs) range, thus demonstrating the realization of a low-cost material with promising perspectives for applications in Si-based photonics. - Highlights: • Synthesis of ultrathin Si nanowires (NWs) by metal-assisted chemical etching • Synthesis of NW/carbon nanotube (CNT) hybrid systems • Structural characterization of Si NWs and Si NW/CNT • Room temperature photoluminescence (PL) properties of Si NWs and of Si NW/CNT • Tuning of the PL properties of the Si NW/CNT hybrid system.

Current Controlled Magnetization Switching in Cylindrical Nanowires for High-Density 3D Memory Applications

KAUST Repository

Mohammed, Hanan

2018-04-18

A next-generation memory device utilizing a three-dimensional nanowire system requires the reliable control of domain wall motion. In this letter, domain walls are studied in cylindrical nanowires consisting of alternating segments of cobalt and nickel. The material interfaces acting as domain wall pinning sites, are utilized in combination with current pulses, to control the position of the domain wall, which is monitored using magnetoresistance measurements. Magnetic force microscopy results further confirm the occurrence of current assisted domain wall depinning. Data bits are therefore shifted along the nanowire by sequentially pinning and depinning a domain wall between successive interfaces, a requirement necessary for race-track type memory devices. We demonstrate that the direction, amplitude and duration of the applied current pulses determine the propagation of the domain wall across pinning sites. These results demonstrate a multi-bit cylindrical nanowire device, utilizing current assisted data manipulation. The prospect of sequential pinning and depinning in these nanowires allows the bit density to increase by several Tbs, depending on the number of segments within these nanowires.

Current Controlled Magnetization Switching in Cylindrical Nanowires for High-Density 3D Memory Applications

KAUST Repository

Mohammed, Hanan; Corte-Leó n, Hector; Ivanov, Yurii P.; Lopatin, Sergei; Moreno, Julian A.; Chuvilin, Andrey; Salimath, Akshaykumar; Manchon, Aurelien; Kazakova, Olga; Kosel, Jü rgen

2018-01-01

A next-generation memory device utilizing a three-dimensional nanowire system requires the reliable control of domain wall motion. In this letter, domain walls are studied in cylindrical nanowires consisting of alternating segments of cobalt and nickel. The material interfaces acting as domain wall pinning sites, are utilized in combination with current pulses, to control the position of the domain wall, which is monitored using magnetoresistance measurements. Magnetic force microscopy results further confirm the occurrence of current assisted domain wall depinning. Data bits are therefore shifted along the nanowire by sequentially pinning and depinning a domain wall between successive interfaces, a requirement necessary for race-track type memory devices. We demonstrate that the direction, amplitude and duration of the applied current pulses determine the propagation of the domain wall across pinning sites. These results demonstrate a multi-bit cylindrical nanowire device, utilizing current assisted data manipulation. The prospect of sequential pinning and depinning in these nanowires allows the bit density to increase by several Tbs, depending on the number of segments within these nanowires.

Mechanical behavior enhancement of ZnO nanowire by embedding different nanowires

Science.gov (United States)

Vazinishayan, Ali; Yang, Shuming; Lambada, Dasaradha Rao; Wang, Yiming

2018-06-01

In this work, we employed commercial finite element modeling (FEM) software package ABAQUS to analyze mechanical properties of ZnO nanowire before and after embedding with different kinds of nanowires, having different materials and cross-section models such as Au (circular), Ag (pentagonal) and Si (rectangular) using three point bending technique. The length and diameter of the ZnO nanowire were measured to be 12,280 nm and 103.2 nm, respectively. In addition, Au, Ag and Si nanowires were considered to have the length of 12,280 nm and the diameter of 27 nm. It was found that after embedding Si nanowire with rectangular cross-section into the ZnO nanowire, the distribution of Von Misses stresses criterion, displacement and strain were decreased than the other nanowires embedded. The highest stiffness, the elastic deformation and the high strength against brittle failure have been made by Si nanowire comparison to the Au and Ag nanowires, respectively.

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

KAUST Repository

Zhai, Yujia

2012-11-26

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

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

KAUST Repository

Zhai, Yujia; Palard, Marylene; Mathew, Leo; Hussain, Muhammad Mustafa; Willson, Grant Grant; Tutuc, Emanuel; Banerjee, Sanjay Kumar

2012-01-01

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

Synthesis, optical properties and residual strain effect of GaN nanowires generated via metal-assisted photochemical electroless etching

KAUST Repository

Najar, Adel

2017-04-18

Herein, we report on the studies of GaN nanowires (GaN NWs) prepared via a metal-assisted photochemical electroless etching method with Pt as the catalyst. It has been found that etching time greatly influences the growth of GaN NWs. The density and the length of nanowires increased with longer etching time, and excellent substrate coverage was observed. The average nanowire width and length are around 35 nm and 10 μm, respectively. Transmission electron microscopy (TEM) shows a single-crystalline wurtzite structure and is confirmed by X-ray measurements. The synthesis mechanism of GaN NWs using the metal-assisted photochemical electroless etching method was presented. Photoluminescence (PL) measurements of GaN NWs show red-shift PL peaks compared to the as-grown sample associated with the relaxation of compressive stress. Furthermore, a shift of the E2 peak to the lower frequency in the Raman spectra for the samples etched for a longer time confirms such a stress relaxation. Based on Raman measurements, the compressive stress σxx and the residual strain εxx were evaluated to be 0.23 GPa and 2.6 × 10−4, respectively. GaN NW synthesis using a low cost method might be used for the fabrication of power optoelectronic devices and gas sensors.

Register-based estimates of parents' coresidence in Sweden, 1969-2007

Directory of Open Access Journals (Sweden)

Elizabeth Thomson

2013-12-01

Full Text Available Background: Many of the dramatic changes in family formation and dissolution observed in wealthy countries over the past 60 years are tracked through vital statistics or censuses. The signature change in family behavior -- non-marital cohabitation -- is not, however, registered in most settings. Objective: We evaluate the quality of new register-based estimates of parents' union status at birth and of separation during the childrearing years. Methods: Parents of a common child are identified through the Multi-Generation Register that links each child to each parent and therefore each parent to each other. The Total Population Register identifies the property at which each parent is registered at the end of each year. We use the five-year censuses 1960-1990 as one standard of comparison because the censuses identify the dwelling unit for each parent on the census date. Results: Property-based estimates of parents' coresidence compare very well to census reports. Register-based estimates are virtually identical with those produced from the 1992 Swedish Fertility and Family Survey; differences between register estimates and those produced from the 1991 and 2000 Level of Living Survey can be explained by differences in measurement of marriage and cohabitation. Conclusions: Estimates of parents' cohabitation based on annual, property-level registration are of sufficient quality for their use in substantive analyses of union status at birth and parents' separation in Sweden. Comments: Although register-based estimates of parents' coresidence at a child's birth or afterwards can be generated only for a select group of countries, their use can be fruitful for understanding more general processes of family change. Centralized administrative registers exist in many countries but have not been made fully available for research therefore losing much of the potential value.

Site-selective fabrication of conducting molecular nanowires based on electrocrystallization

International Nuclear Information System (INIS)

Hasegawa, H.; Kubota, T.; Mashiko, S.

2005-01-01

We have grown nanowires in a selective position by using an electrochemical process and alternating current. Nanoscale electrocrystallization was carried out in an axially substituted phthalocyanine solution using substrates with two electrodes formed by photolithography. The growth area was limited to the narrowest part of the gap between the tips of the electrodes by using tapered electrodes. The nanowires obtained had a width of approximately 100 nm and a length of more than 1 μm. Analysis of the selected-area electron diffraction pattern showed that the nanowire structure was identical to that of bulk crystal

Silicon nanowire based high brightness, pulsed relativistic electron source

Directory of Open Access Journals (Sweden)

Deep Sarkar

2017-06-01

Full Text Available We demonstrate that silicon nanowire arrays efficiently emit relativistic electron pulses under irradiation by a high-intensity, femtosecond, and near-infrared laser (∼1018 W/cm2, 25 fs, 800 nm. The nanowire array yields fluxes and charge per bunch that are 40 times higher than those emitted by an optically flat surface, in the energy range of 0.2–0.5 MeV. The flux and charge yields for the nanowires are observed to be directional in nature unlike that for planar silicon. Particle-in-cell simulations establish that such large emission is caused by the enhancement of the local electric fields around a nanowire, which consequently leads to an enhanced absorption of laser energy. We show that the high-intensity contrast (ratio of picosecond pedestal to femtosecond peak of the laser pulse (10−9 is crucial to this large yield. We extend the notion of surface local-field enhancement, normally invoked in low-order nonlinear optical processes like second harmonic generation, optical limiting, etc., to ultrahigh laser intensities. These electron pulses, expectedly femtosecond in duration, have potential application in imaging, material modification, ultrafast dynamics, terahertz generation, and fast ion sources.

Selective growth of gallium nitride nanowires by femtosecond laser patterning

International Nuclear Information System (INIS)

Ng, D.K.T.; Hong, M.H.; Tan, L.S.; Zhou, Y.; Chen, G.X.

2008-01-01

We report on gallium nitride (GaN) nanowires grown using pulsed laser ablation, adopting the vapor-liquid-solid (VLS) growth mechanism. The GaN nanowires are obtained based on the principle that a catalyst is required to initiate the nanowires growth. Locations of the GaN nanowires are patterned using femtosecond laser and focused ion beam. Scanning electron microscopy (SEM) is used to characterize the nanowires. This patterning of GaN nanowires will enable selective growth of nanowires and bottom-up assembly of integrated electronic and photonic devices

Selective growth of gallium nitride nanowires by femtosecond laser patterning

Energy Technology Data Exchange (ETDEWEB)

Ng, D.K.T. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, Agency for Science, Technology and Research, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Hong, M.H. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, Agency for Science, Technology and Research, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)], E-mail: HONG_Minghui@dsi.a-star.edu.sg; Tan, L.S. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Zhou, Y. [Data Storage Institute, Agency for Science, Technology and Research, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Department of Mechanical Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Chen, G.X. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)

2008-01-31

We report on gallium nitride (GaN) nanowires grown using pulsed laser ablation, adopting the vapor-liquid-solid (VLS) growth mechanism. The GaN nanowires are obtained based on the principle that a catalyst is required to initiate the nanowires growth. Locations of the GaN nanowires are patterned using femtosecond laser and focused ion beam. Scanning electron microscopy (SEM) is used to characterize the nanowires. This patterning of GaN nanowires will enable selective growth of nanowires and bottom-up assembly of integrated electronic and photonic devices.

Nanowires and nanobelts, v.2 nanowires and nanobelts of functional materials

CERN Document Server

Wang, Zhong Lin

2010-01-01

Nanowires, nanobelts, nanoribbons, nanorods ..., are a new class of quasi-one-dimensional materials that have been attracting a great research interest in the last few years. These non-carbon based materials have been demonstrated to exhibit superior electrical, optical, mechanical and thermal properties, and can be used as fundamental building blocks for nano-scale science and technology, ranging from chemical and biological sensors, field effect transistors to logic circuits. Nanocircuits built using semiconductor nanowires demonstrated were declared a ""breakthrough in science"" by Science

Simulation study of dielectrophoretic assembly of nanowire between electrode pairs

Energy Technology Data Exchange (ETDEWEB)

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

2015-07-15

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

Editorial: HOW THE CENTRE OF MALAYSIAN POLITICS SHIFTED TO THE ISLAMIST REGISTER 1969-2009

Directory of Open Access Journals (Sweden)

Editor Al-Jami'ah: Journal of Islamic Studies

2009-02-01

Full Text Available One of the most obvious observations that can be made about the form and content of Malaysian politics, political discourse and political culture today is how the country has shifted to a visibly more Islamist register, with the symbols and vocabulary of political Islam gaining prominence and visibility over the past four decades. This is particularly true in the case of Malaysia’s civil society space, which was once dominated by secular Non-Governmental Organisations (NGOs, mass movements and lobby groups. Today, however, we are looking at the relatively new phenomenon of a Malaysian civil society space which is increasingly being dominated by Islamist civil society movements that operate within the constitutional framework of the country but which are pushing for a clearly religious-communitarian agenda, namely the Islamisation of Malaysian society and politics. How did this come about?

Local sensor based on nanowire field effect transistor from inhomogeneously doped silicon on insulator

Science.gov (United States)

Presnov, Denis E.; Bozhev, Ivan V.; Miakonkikh, Andrew V.; Simakin, Sergey G.; Trifonov, Artem S.; Krupenin, Vladimir A.

2018-02-01

We present the original method for fabricating a sensitive field/charge sensor based on field effect transistor (FET) with a nanowire channel that uses CMOS-compatible processes only. A FET with a kink-like silicon nanowire channel was fabricated from the inhomogeneously doped silicon on insulator wafer very close (˜100 nm) to the extremely sharp corner of a silicon chip forming local probe. The single e-beam lithographic process with a shadow deposition technique, followed by separate two reactive ion etching processes, was used to define the narrow semiconductor nanowire channel. The sensors charge sensitivity was evaluated to be in the range of 0.1-0.2 e /√{Hz } from the analysis of their transport and noise characteristics. The proposed method provides a good opportunity for the relatively simple manufacture of a local field sensor for measuring the electrical field distribution, potential profiles, and charge dynamics for a wide range of mesoscopic objects. Diagnostic systems and devices based on such sensors can be used in various fields of physics, chemistry, material science, biology, electronics, medicine, etc.

Quantum cost optimized design of 4-bit reversible universal shift register using reduced number of logic gate

Science.gov (United States)

Maity, H.; Biswas, A.; Bhattacharjee, A. K.; Pal, A.

In this paper, we have proposed the design of quantum cost (QC) optimized 4-bit reversible universal shift register (RUSR) using reduced number of reversible logic gates. The proposed design is very useful in quantum computing due to its low QC, less no. of reversible logic gate and less delay. The QC, no. of gates, garbage outputs (GOs) are respectively 64, 8 and 16 for proposed work. The improvement of proposed work is also presented. The QC is 5.88% to 70.9% improved, no. of gate is 60% to 83.33% improved with compared to latest reported result.

High performance Si nanowire field-effect-transistors based on a CMOS inverter with tunable threshold voltage.

Science.gov (United States)

Van, Ngoc Huynh; Lee, Jae-Hyun; Sohn, Jung Inn; Cha, Seung Nam; Whang, Dongmok; Kim, Jong Min; Kang, Dae Joon

2014-05-21

We successfully fabricated nanowire-based complementary metal-oxide semiconductor (NWCMOS) inverter devices by utilizing n- and p-type Si nanowire field-effect-transistors (NWFETs) via a low-temperature fabrication processing technique. We demonstrate that NWCMOS inverter devices can be operated at less than 1 V, a significantly lower voltage than that of typical thin-film based complementary metal-oxide semiconductor (CMOS) inverter devices. This low-voltage operation was accomplished by controlling the threshold voltage of the n-type Si NWFETs through effective management of the nanowire (NW) doping concentration, while realizing high voltage gain (>10) and ultra-low static power dissipation (≤3 pW) for high-performance digital inverter devices. This result offers a viable means of fabricating high-performance, low-operation voltage, and high-density digital logic circuits using a low-temperature fabrication processing technique suitable for next-generation flexible electronics.

Corrosion detection of nanowires by magnetic sensors

KAUST Repository

Kosel, Jü rgen; Amara, Selma; Ivanov, Iurii; Blanco, Mario

2017-01-01

Disclosed are various embodiments related to a corrosion detection device for detecting corrosive environments. A corrosion detection device comprises a magnetic sensor and at least one magnetic nanowire disposed on the magnetic sensor. The magnetic sensor is configured to detect corrosion of the one or more magnetic nanowires based at least in part on a magnetic field of the one or more magnetic nanowires.

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.

Synthetic and effect of annealing on the luminescent properties of ZnO nanowire

Energy Technology Data Exchange (ETDEWEB)

Mo, Zhao-Jun, E-mail: mzjmzj163@163.com [Institute of Material Physics, Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education of Ministry of Education, Tianjin University of Technology, Tianjin 300191 (China); Hao, Zhi-Hong [Tianjin Vocational Institute, Tianjin (China); Wu, Hai-Zhen; Yang, Qing; Zhuo, Ping; Yang, Hui; Xu, Jian-Ping; Zhang, Xiao-Song [Institute of Material Physics, Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education of Ministry of Education, Tianjin University of Technology, Tianjin 300191 (China); Li, Lan, E-mail: lilan2000us@126.com [Institute of Material Physics, Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education of Ministry of Education, Tianjin University of Technology, Tianjin 300191 (China)

2016-07-15

ZnO nanowires were successfully fabricated by using the hydrothermal method in the existence of the poly ethylene glycol (PEG) with the molecular weight of 200. The experimental results exhibit that the ZnO nanowires with the diameter of ~30 nm and the length of ten micrometers. PL spectra show a weak ultraviolet emission and an intense broad visible emission band for as-grown and annealed samples. These visible emission bands exhibit red-shifts from green (545 nm) to yellow (580 nm) and blue-shifts from yellow (580 nm) to green (520 nm) by annealing at aerobic or anaerobic environment, it indicates that the defect types are changed by annealed at different environment. Additionally, the red-shifts (520 nm) and blue-shifts (580) can match up the bimodal lorentzian fitting (520 nm and 583 nm) of as-growth, which suggest that the visible emission band (545 nm) is closely related to oxygen defects. The oxygen atomic can enter into the crystal lattice of ZnO and decrease the oxygen vacancy in air or oxygen, whereas, more oxygen vacancy defects is gave rise in vacuum annealed. We guess the energy levels of the intrinsic defects in ZnO nanowire maybe like that: the electrons of Zn{sub i} defects compound with holes of V{sub Zn}, O{sub i} and O{sub Zn} levels and conform to the yellow emission, and the green emission corresponds to the electron transition from the association defects deep donor level to the valence band.

A nanowire based triboelectric nanogenerator for harvesting water wave energy and its applications

Science.gov (United States)

Li, Xiaoyi; Tao, Juan; Zhu, Jing; Pan, Caofeng

2017-07-01

The ocean wave energy is one of the most promising renewable and clean energy sources for human life, which is the so-called "Blue energy." In this work, a nanowire based triboelectric nanogenerator was designed for harvesting wave energy. The nanowires on the surface of FEP largely raise the contacting area with water and also make the polymer film hydrophobic. The output can reach 10 μ A and 200 V. When combined with a capacitor, an infrared emitter, and a receiver, a self-powered wireless infrared system is fabricated, which can be used in the fields of communication and detecting.

Effects of marital status and shift work on family function among registered nurses.

Science.gov (United States)

Tai, Shu-Yu; Lin, Pei-Chen; Chen, Yao-Mei; Hung, Hsin-Chia; Pan, Chih-Hong; Pan, Shung-Mei; Lee, Chung-Yin; Huang, Chia-Tsuan; Wu, Ming-Tsang

2014-01-01

This study aims to assess the interactive effect of marital status and shift work on family function. A population-based sample of 1,438 nurses between the ages of 20-45 yr was recruited from Taiwan during the period from July 2005 to April 2006 using a mailed questionnaire. The self-administered questionnaire contained information about demographic data, work status, shift work schedule, and the Family APGAR (Adaptation, Partnership, Growth, Affection, and Resolve) Scale, to evaluate family function. Compared to day shift nurses, non-night and rotation shift nurses had 1.53- and 1.38-fold (95% CI=1.09-2.14 and 1.01-1.88) risk to have poor family function after adjusting for other covariates. Married nurses, by contrast, had a 0.44-fold (95% CI=0.29-0.66) risk to have poor family function compared to single nurses. In addition, married nurses who worked non-night or rotation shifts had a significantly higher percent of poor family function than those married nurses working day shifts; however, similar results were not replicated in single nurses. We concluded that shift work and marital status could influence family function.

Effects of Marital Status and Shift Work on Family Function among Registered Nurses

Science.gov (United States)

TAI, Shu-Yu; LIN, Pei-Chen; CHEN, Yao-Mei; HUNG, Hsin-Chia; PAN, Chih-Hong; PAN, Shung-Mei; LEE, Chung-Yin; HUANG, Chia-Tsuan; WU, Ming-Tsang

2014-01-01

This study aims to assess the interactive effect of marital status and shift work on family function. A population-based sample of 1,438 nurses between the ages of 20–45 yr was recruited from Taiwan during the period from July 2005 to April 2006 using a mailed questionnaire. The self-administered questionnaire contained information about demographic data, work status, shift work schedule, and the Family APGAR (Adaptation, Partnership, Growth, Affection, and Resolve) Scale, to evaluate family function. Compared to day shift nurses, non-night and rotation shift nurses had 1.53- and 1.38-fold (95% CI=1.09–2.14 and 1.01–1.88) risk to have poor family function after adjusting for other covariates. Married nurses, by contrast, had a 0.44-fold (95% CI=0.29–0.66) risk to have poor family function compared to single nurses. In addition, married nurses who worked non-night or rotation shifts had a significantly higher percent of poor family function than those married nurses working day shifts; however, similar results were not replicated in single nurses. We concluded that shift work and marital status could influence family function. PMID:24909112

Synthesis of Oxidation-Resistant Cupronickel Nanowires for Transparent Conducting Nanowire Networks

Energy Technology Data Exchange (ETDEWEB)

Rathmall, Aaron [Duke University; Nguyen, Minh [Duke University; Wiley, Benjamin J [Duke University

2012-01-01

Nanowires of copper can be coated from liquids to create flexible, transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these nanowire films is that copper is prone to oxidation. It was hypothesized that the resistance to oxidation could be improved by coating copper nanowires with nickel. This work demonstrates a method for synthesizing copper nanowires with nickel shells as well as the properties of cupronickel nanowires in transparent conducting films. Time- and temperature-dependent sheet resistance measurements indicate that the sheet resistance of copper and silver nanowire films will double after 3 and 36 months at room temperature, respectively. In contrast, the sheet resistance of cupronickel nanowires containing 20 mol % nickel will double in about 400 years. Coating copper nanowires to a ratio of 2:1 Cu:Ni gave them a neutral gray color, making them more suitable for use in displays and electrochromic windows. These properties, and the fact that copper and nickel are 1000 times more abundant than indium or silver, make cupronickel nanowires a promising alternative for the sustainable, efficient production of transparent conductors.

Enhanced photovoltaic performance of an inclined nanowire array solar cell.

Science.gov (United States)

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

2015-11-30

An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays.

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.

Reversal modes in asymmetric Ni nanowires

Energy Technology Data Exchange (ETDEWEB)

Leighton, B.; Pereira, A. [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Escrig, J., E-mail: jescrigm@gmail.com [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

2012-11-15

We have investigated the evolution of the magnetization reversal mechanism in asymmetric Ni nanowires as a function of their geometry. Circular nanowires are found to reverse their magnetization by the propagation of a vortex domain wall, while in very asymmetric nanowires the reversal is driven by the propagation of a transverse domain wall. The effect of shape asymmetry of the wire on coercivity and remanence is also studied. Angular dependence of the remanence and coercivity is also addressed. Tailoring the magnetization reversal mechanism in asymmetric nanowires can be useful for magnetic logic and race-track memory, both of which are based on the displacement of magnetic domain walls. Finally, an alternative method to detect the presence of magnetic drops is proposed. - Highlights: Black-Right-Pointing-Pointer Asymmetry strongly modifies the magnetic behavior of a wire. Black-Right-Pointing-Pointer Very asymmetric nanowires reverse their magnetization by a transverse domain wall. Black-Right-Pointing-Pointer An alternative method to detect the presence of magnetic drops is proposed. Black-Right-Pointing-Pointer Tailoring the reversal mode in asymmetric nanowires can be useful for potential applications.

Coherently Strained Si-SixGe1-x Core-Shell Nanowire Heterostructures.

Science.gov (United States)

Dillen, David C; Wen, Feng; Kim, Kyounghwan; Tutuc, Emanuel

2016-01-13

Coherently strained Si-SixGe1-x core-shell nanowire heterostructures are expected to possess a positive shell-to-core conduction band offset, allowing for quantum confinement of electrons in the Si core. We report the growth of epitaxial, coherently strained Si-SixGe1-x core-shell heterostructures through the vapor-liquid-solid mechanism for the Si core, followed in situ by the epitaxial SixGe1-x shell growth using ultrahigh vacuum chemical vapor deposition. The Raman spectra of individual nanowires reveal peaks associated with the Si-Si optical phonon mode in the Si core and the Si-Si, Si-Ge, and Ge-Ge vibrational modes of the SixGe1-x shell. The core Si-Si mode displays a clear red-shift compared to unstrained, bare Si nanowires thanks to the lattice mismatch-induced tensile strain, in agreement with calculated values using a finite-element continuum elasticity model combined with lattice dynamic theory. N-type field-effect transistors using Si-SixGe1-x core-shell nanowires as channel are demonstrated.

Validity of a hospital-based obstetric register using medical records as reference

DEFF Research Database (Denmark)

Brixval, Carina Sjöberg; Thygesen, Lau Caspar; Johansen, Nanna Roed

2015-01-01

BACKGROUND: Data from hospital-based registers and medical records offer valuable sources of information for clinical and epidemiological research purposes. However, conducting high-quality epidemiological research requires valid and complete data sources. OBJECTIVE: To assess completeness...... and validity of a hospital-based clinical register - the Obstetric Database - using a national register and medical records as references. METHODS: We assessed completeness of a hospital-based clinical register - the Obstetric Database - by linking data from all women registered in the Obstetric Database...... Database therefore offers a valuable source for examining clinical, administrative, and research questions....

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-01

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

Spin-orbit qubit in a semiconductor nanowire.

Science.gov (United States)

Nadj-Perge, S; Frolov, S M; Bakkers, E P A M; Kouwenhoven, L P

2010-12-23

Motion of electrons can influence their spins through a fundamental effect called spin-orbit interaction. This interaction provides a way to control spins electrically and thus lies at the foundation of spintronics. Even at the level of single electrons, the spin-orbit interaction has proven promising for coherent spin rotations. Here we implement a spin-orbit quantum bit (qubit) in an indium arsenide nanowire, where the spin-orbit interaction is so strong that spin and motion can no longer be separated. In this regime, we realize fast qubit rotations and universal single-qubit control using only electric fields; the qubits are hosted in single-electron quantum dots that are individually addressable. We enhance coherence by dynamically decoupling the qubits from the environment. Nanowires offer various advantages for quantum computing: they can serve as one-dimensional templates for scalable qubit registers, and it is possible to vary the material even during wire growth. Such flexibility can be used to design wires with suppressed decoherence and to push semiconductor qubit fidelities towards error correction levels. Furthermore, electrical dots can be integrated with optical dots in p-n junction nanowires. The coherence times achieved here are sufficient for the conversion of an electronic qubit into a photon, which can serve as a flying qubit for long-distance quantum communication.

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.

CuO-In2O3 Core-Shell Nanowire Based Chemical Gas Sensors

Directory of Open Access Journals (Sweden)

Xiaoxin Li

2014-01-01

Full Text Available The CuO-In2O3 core-shell nanowire was fabricated by a two-step method. The CuO nanowire core (NWs was firstly grown by the conventional thermal oxidation of Cu meshes at 500°C for 5 hours. Then, the CuO nanowires were immersed into the suspension of amorphous indium hydroxide deposited from the In(AC3 solution by ammonia. The CuO nanowires coated with In(OH3 were subsequently heated at 600°C to form the crystalline CuO-In2O3 core-shell structure, with In2O3 nanocrystals uniformly anchored on the CuO nanowires. The gas sensing properties of the formed CuO-In2O3 core-shell nanowires were investigated by various reducing gases such as hydrogen, carbon monoxide, and propane at elevated temperature. The sensors using the CuO-In2O3 nanowires show improved sensing performance to hydrogen and propane but a suppressed response to carbon monoxide, which could be attributed to the enhanced catalytic properties of CuO with the coated porous In2O3 shell and the p-n junction formed at the core-shell interface.

Synthesis of uniform CdS nanowires in high yield and its single nanowire electrical property

International Nuclear Information System (INIS)

Yan Shancheng; Sun Litao; Qu Peng; Huang Ninping; Song Yinchen; Xiao Zhongdang

2009-01-01

Large-scale high quality CdS nanowires with uniform diameter were synthesized by using a rapid and simple solvothermal route. Field emission scan electron microscopy (FESEM) and transmission electron microscopy (TEM) images show that the CdS nanowires have diameter of about 26 nm and length up to several micrometres. High resolution TEM (HRTEM) study indicates the single-crystalline nature of CdS nanowires with an oriented growth along the c-axis direction. The optical properties of the products were characterized by UV-vis absorption spectra, photoluminescence spectra and Raman spectra. The resistivity, electron concentration and electron mobility of single NW are calculated by fitting the symmetric I-V curves measured on single NW by the metal-semiconductor-metal model based on thermionic field emission theory. - Graphical abstract: Large-scale high quality CdS nanowires (NWs) with uniform diameter were synthesized by using a rapid and simple solvothermal route. The reaction time is reduced to 2 h, comparing to other synthesis which needed long reaction time up to 12 h. In addition, the as-prepared CdS nanowires have more uniform diameter and high yield. More importantly, the I-V curve of present single CdS nanowire has a good symmetric characteristic as expected by the theory.

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.

Biotemplated Synthesis of PZT Nanowires

Science.gov (United States)

2013-11-25

electromechanical coupling coefficient , Y is the Young’s modulus, and Ri is intrinsic resistance. The PZT nanowire- based film is taken to have negligible...robotic actuation, and bioMEMS. Lead zirconate titanate ( PZT ), in particular, has attracted significant attention, owing to its superior...electromechanical conversion performance. Yet, the ability to synthesize crystalline PZT nanowires with reproducible and well-controlled properties remains a

Recovery Based Nanowire Field-Effect Transistor Detection of Pathogenic Avian Influenza DNA

Science.gov (United States)

Lin, Chih-Heng; Chu, Chia-Jung; Teng, Kang-Ning; Su, Yi-Jr; Chen, Chii-Dong; Tsai, Li-Chu; Yang, Yuh-Shyong

2012-02-01

Fast and accurate diagnosis is critical in infectious disease surveillance and management. We proposed a DNA recovery system that can easily be adapted to DNA chip or DNA biosensor for fast identification and confirmation of target DNA. This method was based on the re-hybridization of DNA target with a recovery DNA to free the DNA probe. Functionalized silicon nanowire field-effect transistor (SiNW FET) was demonstrated to monitor such specific DNA-DNA interaction using high pathogenic strain virus hemagglutinin 1 (H1) DNA of avian influenza (AI) as target. Specific electric changes were observed in real-time for AI virus DNA sensing and device recovery when nanowire surface of SiNW FET was modified with complementary captured DNA probe. The recovery based SiNW FET biosensor can be further developed for fast identification and further confirmation of a variety of influenza virus strains and other infectious diseases.

Au nanowire junction breakup through surface atom diffusion

Science.gov (United States)

Vigonski, Simon; Jansson, Ville; Vlassov, Sergei; Polyakov, Boris; Baibuz, Ekaterina; Oras, Sven; Aabloo, Alvo; Djurabekova, Flyura; Zadin, Vahur

2018-01-01

Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200 °C, 400 °C, 600 °C and 700 °C) during a time period of 10 min. We show that nanowires are especially prone to fragmentation around junctions and crossing points even at comparatively low temperatures. The fragmentation process is highly temperature dependent and the junction region breaks up at a lower temperature than a single nanowire. We develop a gold parametrization for kinetic Monte Carlo simulations and demonstrate the surface diffusion origin of the nanowire junction fragmentation. We show that nanowire fragmentation starts at the junctions with high reliability and propose that aligning nanowires in a regular grid could be used as a technique for fabricating arrays of nanodots.

All-Optical 40 Gbit/s Regenerative Wavelength Conversion Based on Cross-Phase Modulation in a Silicon Nanowire

DEFF Research Database (Denmark)

Jensen, Asger Sellerup; Hu, Hao; Ji, Hua

2013-01-01

We successfully demonstrate all-optical regeneration of a 40 Gbit/s signal based on cross-phase modulation in a silicon nanowire. Bit-error-rate measurements show an average of 1.7dB improvement in receiver sensitivity after the regeneration.......We successfully demonstrate all-optical regeneration of a 40 Gbit/s signal based on cross-phase modulation in a silicon nanowire. Bit-error-rate measurements show an average of 1.7dB improvement in receiver sensitivity after the regeneration....

Transformation of bulk alloys to oxide nanowires

Science.gov (United States)

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

2017-01-01

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

A nanowire based triboelectric nanogenerator for harvesting water wave energy and its applications

Directory of Open Access Journals (Sweden)

Xiaoyi Li

2017-07-01

Full Text Available The ocean wave energy is one of the most promising renewable and clean energy sources for human life, which is the so-called “Blue energy.” In this work, a nanowire based triboelectric nanogenerator was designed for harvesting wave energy. The nanowires on the surface of FEP largely raise the contacting area with water and also make the polymer film hydrophobic. The output can reach 10 μ A and 200 V. When combined with a capacitor, an infrared emitter, and a receiver, a self-powered wireless infrared system is fabricated, which can be used in the fields of communication and detecting.

SAW Humidity Sensor Sensitivity Enhancement via Electrospraying of Silver Nanowires

Directory of Open Access Journals (Sweden)

Farid Sayar Irani

2016-11-01

Full Text Available In this research, we investigated the influence of the surface coatings of silver nanowires on the sensitivity of surface acoustic wave (SAW humidity sensors. Silver nanowires, with poly(vinylpyrrolidone (PVP, which is a hydrophilic capping agent, were chemically synthesized, with an average length of 15 µm and an average diameter of 60 nm. Humidity sensors, with 433 MHz frequency dual-port resonator Rayleigh-SAW devices, were coated by silver nanowires (AgNWs using the electrospray coating method. It was demonstrated that increasing thickness of coated AgNW on the surfaces of SAW devices results in increased sensitivity. The highest frequency shift (262 kHz in these SAW devices was obtained with an injection of 0.5 mL of the AgNW solution with a concentration of 0.5 mg/mL at an injection rate of 1 mL/h. It also showed the highest humidity sensitivity among the other prepared SAW devices.

Fabrication and optical properties of TiO sub 2 nanowire arrays made by sol-gel electrophoresis deposition into anodic alumina membranes

CERN Document Server

Lin, Y; Yuan, X Y; Xie, T; Zhang, L D

2003-01-01

Ordered TiO sub 2 nanowire arrays have been successfully fabricated into the nanochannels of a porous anodic alumina membrane by sol-gel electrophoretic deposition. After annealing at 500 deg. C, the TiO sub 2 nanowire arrays and the individual nanowires were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and x-ray diffraction (XRD). SEM and TEM images show that these nanowires are dense and continuous with a uniform diameter throughout their entire length. XRD and SAED analysis together indicate that these TiO sub 2 nanowires crystallize in the anatase polycrystalline structure. The optical absorption band edge of TiO sub 2 nanowire arrays exhibits a blue shift with respect of that of the bulk TiO sub 2 owing to the quantum size effect.

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

Science.gov (United States)

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

2008-10-21

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

Associations of rotational shift work and night shift status with hypertension: a systematic review and meta-analysis.

Science.gov (United States)

Manohar, Sandhya; Thongprayoon, Charat; Cheungpasitporn, Wisit; Mao, Michael A; Herrmann, Sandra M

2017-10-01

The reported risks of hypertension (HTN) in rotating shift and night shift workers are controversial. The objective of this meta-analysis was to assess the association between shift work status and HTN. A literature search was performed using MEDLINE, EMBASE and Cochrane Database from inception through October 2016. Studies that reported odds ratios (OR) comparing the risk of HTN in shift workers were included. A prespecified subgroup analysis by rotating shift and night shift statuses were also performed. Pooled OR and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method. The protocol for this study is registered with International Prospective Register of Systematic Reviews; no. CRD42016051843. Twenty-seven observational studies (nine cohort and 18 cross-sectional studies) with a total of 394 793 individuals were enrolled. The pooled ORs of HTN in shift workers in cohort and cross-sectional studies were 1.31 (95% CI, 1.07-1.60) and 1.10 (95% CI, 1.00-1.20), respectively. When meta-analysis was restricted only to cohort studies in rotating shift, the pooled OR of HTN in rotating shift workers was 1.34 (95% CI, 1.08-1.67). The data regarding night shift and HTN in cohort studies was limited. The pooled OR of HTN in night shift workers in cross-sectional studies was 1.07 (95% CI, 0.85-1.35). Based on the findings of our meta-analysis, shiftwork status may play an important role in HTN, as there is a significant association between rotating shift work and HTN. However, there is no significant association between night shift status and risk of HTN.

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

Science.gov (United States)

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

2017-12-12

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

An effective surface-enhanced Raman scattering template based on a Ag nanocluster-ZnO nanowire array

International Nuclear Information System (INIS)

Deng, S; Zhang, X; Loh, K P; Fan, H M; Sow, C H; Cheng, C-L; Foo, Y L

2009-01-01

An effective surface-enhanced Raman scattering (SERS) template based on a 3D hybrid Ag nanocluster (NC)-decorated ZnO nanowire array was fabricated through a simple process of depositing Ag NCs on ZnO nanowire arrays. The effects of particle size and excitation energy on the Raman scattering in these hybrid systems have been investigated using rhodamine 6G as a standard analyte. The results indicate that the hybrid nanosystem with 150 nm Ag NCs produces a larger SERS enhancement factor of 3.2 x 10 8 , which is much higher than that of 10 nm Ag NCs (6.0 x 10 6 ) under 532 nm excitation energy. The hybrid nanowire arrays were further applied to obtain SERS spectra of the two-photon absorption (TPA) chromophore T7. Finite-difference time-domain simulations reveal the presence of an enhanced field associated with inter-wire plasmon coupling of the 150 nm Ag NCs on adjacent ZnO nanowires; such a field was absent in the case of the 10 nm Ag NC-coated ZnO nanowire. Such hybrid nanosystems could be used as SERS substrates more effectively than assembled Ag NC film due to the enhanced light-scattering local field and the inter-wire plasmon-enhanced electromagnetic field.

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

Science.gov (United States)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

Influence factors of the inter-nanowire thermal contact resistance in the stacked nanowires

Science.gov (United States)

Wu, Dongxu; Huang, Congliang; Zhong, Jinxin; Lin, Zizhen

2018-05-01

The inter-nanowire thermal contact resistance is important for tuning the thermal conductivity of a nanocomposite for thermoelectric applications. In this paper, the stacked copper nanowires are applied for studying the thermal contact resistance. The stacked copper nanowires are firstly made by the cold-pressing method, and then the nanowire stacks are treated by sintering treatment. With the effect of the volumetric fraction of nanowires in the stack and the influence of the sintering-temperature on the thermal contact resistance discussed, results show that: The thermal conductivity of the 150-nm copper nanowires can be enlarged almost 2 times with the volumetric fraction increased from 32 to 56% because of the enlarged contact-area and contact number of a copper nanowire. When the sintering temperature increases from 293 to 673 K, the thermal conductivity of the stacked 300-nm nanowires could be enlarged almost 2.5 times by the sintering treatment, because of the improved lattice property of the contact zone. In conclusion, application of a high volumetric fraction or/and a sintering-treatment are effectivity to tune the inter-nanowire thermal contact resistance, and thus to tailor the thermal conductivity of a nanowire network or stack.

Field effect transistors and phototransistors based upon p-type solution-processed PbS nanowires

Science.gov (United States)

Giraud, Paul; Hou, Bo; Pak, Sangyeon; Inn Sohn, Jung; Morris, Stephen; Cha, SeungNam; Kim, Jong Min

2018-02-01

We demonstrate the fabrication of solution processed highly crystalline p-type PbS nanowires via the oriented attachment of nanoparticles. The analysis of single nanowire field effect transistor (FET) devices revealed a hole conduction behaviour with average mobilities greater than 30 cm2 V-1 s-1, which is an order of magnitude higher than that reported to date for p-type PbS colloidal nanowires. We have investigated the response of the FETs to near-infrared light excitation and show herein that the nanowires exhibited gate-dependent photo-conductivities, enabling us to tune the device performances. The responsivity was found to be greater than 104 A W-1 together with a detectivity of 1013 Jones, which benefits from a photogating effect occurring at negative gate voltages. These encouraging detection parameters are accompanied by relatively short switching times of 15 ms at positive gate voltages, resulting from a combination of the standard photoconduction and the high crystallinity of the nanowires. Collectively, these results indicate that solution-processed PbS nanowires are promising nanomaterials for infrared photodetectors as well as p-type nanowire FETs.

Morphology Controlled Fabrication of InN Nanowires on Brass Substrates

Directory of Open Access Journals (Sweden)

Huijie Li

2016-10-01

Full Text Available Growth of semiconductor nanowires on cheap metal substrates could pave the way to the large-scale manufacture of low-cost nanowire-based devices. In this work, we demonstrated that high density InN nanowires can be directly grown on brass substrates by metal-organic chemical vapor deposition. It was found that Zn from the brass substrates is the key factor in the formation of nanowires by restricting the lateral growth of InN. The nanowire morphology is highly dependent on the growth temperature. While at a lower growth temperature, the nanowires and the In droplets have large diameters. At the elevated growth temperature, the lateral sizes of the nanowires and the In droplets are much smaller. Moreover, the nanowire diameter can be controlled in situ by varying the temperature in the growth process. This method is very instructive to the diameter-controlled growth of nanowires of other materials.

Self-Assembled PbSe Nanowire:Perovskite Hybrids

KAUST Repository

Yang, Zhenyu

2015-12-02

© 2015 American Chemical Society. Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

Self-Assembled PbSe Nanowire:Perovskite Hybrids

KAUST Repository

Yang, Zhenyu; Yassitepe, Emre; Voznyy, Oleksandr; Janmohamed, Alyf; Lan, Xinzheng; Levina, Larissa; Comin, Riccardo; Sargent, Edward H.

2015-01-01

© 2015 American Chemical Society. Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

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

International Nuclear Information System (INIS)

Chehata, Nadia; Ltaief, Adnen; Ilahi, Bouraoui; Salem, Bassem; Bouazizi, Abdelaziz; Maaref, Hassen; Baron, Thierry

2014-01-01

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

Quantum interferometer based on GaAs/InAs core/shell nanowires connected to superconducting contacts

Science.gov (United States)

Haas, F.; Dickheuer, S.; Zellekens, P.; Rieger, T.; Lepsa, M. I.; Lüth, H.; Grützmacher, D.; Schäpers, Th

2018-06-01

An interferometer structure was realized based on a GaAs/InAs core/shell nanowire and Nb superconducting electrodes. Two pairs of Nb contacts are attached to the side facets of the nanowire allowing for carrier transport in three different orientations. Owing to the core/shell geometry, the current flows in the tubular conductive InAs shell. In transport measurements with superconducting electrodes directly facing each other, indications of a Josephson supercurrent are found. In contrast for junctions in diagonal and longitudinal configuration a deficiency current is observed, owing to the weaker coupling on longer distances. By applying a magnetic field along the nanowires axis pronounced h/2e flux-periodic oscillations are measured in all three contact configurations. The appearance of these oscillations is explained in terms of interference effects in the Josephson supercurrent and long-range phase-coherent Andreev reflection.

Metal nanogrids, nanowires, and nanofibers for transparent electrodes

KAUST Repository

Hu, Liangbing; Wu, Hui; Cui, Yi

2011-01-01

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

Metal nanogrids, nanowires, and nanofibers for transparent electrodes

KAUST Repository

Hu, Liangbing

2011-10-01

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

Towards low-dimensional hole systems in Be-doped GaAs nanowires

DEFF Research Database (Denmark)

Ullah, A. R.; Gluschke, J. G.; Jeppesen, Peter Krogstrup

2017-01-01

-gates produced using GaAs nanowires with three different Be-doping densities and various AuBe contact processing recipes. We show that contact annealing only brings small improvements for the moderately doped devices under conditions of lower anneal temperature and short anneal time. We only obtain good......GaAs was central to the development of quantum devices but is rarely used for nanowire-based quantum devices with InAs, InSb and SiGe instead taking the leading role. p-type GaAs nanowires offer a path to studying strongly confined 0D and 1D hole systems with strong spin–orbit effects, motivating...... our development of nanowire transistors featuring Be-doped p-type GaAs nanowires, AuBe alloy contacts and patterned local gate electrodes towards making nanowire-based quantum hole devices. We report on nanowire transistors with traditional substrate back-gates and EBL-defined metal/oxide top...

Time-dependent optical response of three-dimensional Au nanoparticle arrays formed on silica nanowires

Science.gov (United States)

Di Mario, Lorenzo; Otomalo, Tadele Orbula; Catone, Daniele; O'Keeffe, Patrick; Tian, Lin; Turchini, Stefano; Palpant, Bruno; Martelli, Faustino

2018-03-01

We present stationary and transient absorption measurements on 3D Au nanoparticle (NP)-decorated Si O2 nanowire arrays. The 3D NP array has been produced by the dewetting of a thin Au film deposited on silica nanowires produced by oxidation of silicon nanowires. The experimental behaviors of the spectral and temporal dynamics observed in the experiment are accurately described by a two-step, three-temperature model. Using an arbitrary set of Au NPs with different aspect ratios, we demonstrate that the width of the experimental spectra, the energy shift of their position with time, and the asymmetry between the two positive wings in the dynamical variation of absorption can all be attributed to the nonuniform shape distribution of the Au NPs in the sample.

Pattern analysis of aligned nanowires in a microchannel

International Nuclear Information System (INIS)

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

2013-01-01

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

Nanoscale Electronic Conditioning for Improvement of Nanowire Light-Emitting-Diode Efficiency.

Science.gov (United States)

May, Brelon J; Belz, Matthew R; Ahamed, Arshad; Sarwar, A T M G; Selcu, Camelia M; Myers, Roberto C

2018-04-24

Commercial III-Nitride LEDs and lasers spanning visible and ultraviolet wavelengths are based on epitaxial films. Alternatively, nanowire-based III-Nitride optoelectronics offer the advantage of strain compliance and high crystalline quality growth on a variety of inexpensive substrates. However, nanowire LEDs exhibit an inherent property distribution, resulting in uneven current spreading through macroscopic devices that consist of millions of individual nanowire diodes connected in parallel. Despite being electrically connected, only a small fraction of nanowires, sometimes current in the ensemble devices. Burn-in electronic conditioning is performed by applying a short-term overload voltage; the nanoshorts experience very high current density, sufficient to render them open circuits, thereby forcing a new current path through more nanowire LEDs in an ensemble device. Current-voltage measurements of individual nanowires are acquired using conductive atomic force microscopy to observe the removal of nanoshorts using burn-in. In macroscopic devices, this results in a 33× increase in peak EL and reduced leakage current. Burn-in conditioning of nanowire ensembles therefore provides a straightforward method to mitigate nonuniformities inherent to nanowire devices.

Direct observation of Au/Ga2O3 peapodded nanowires and their plasmonic behaviors.

Science.gov (United States)

Chen, Po-Han; Hsieh, Chin-Hua; Chen, Sheng-Yu; Wu, Chen-Hwa; Wu, Yi-Jen; Chou, Li-Jen; Chen, Lih-Juann

2010-09-08

Gold-peapodded Ga(2)O(3) nanowires were fabricated successfully in a well-controlled manner by thermal annealing of core-shell gold-Ga(2)O(3) nanowires. During the heating process, the core gold nanowires were broken up into chains of nanoparticles at sufficiently high temperature by the mechanism of Rayleigh instability. In addition, the size, shape, and interspacing between the particles can be manipulated by varying the annealing time and/or the forming gas. The plasmonic behaviors of these nanostructures are investigated by optical spectroscopy. A single nanowire optical device was designed, and its photonic characteristics were investigated. A remarkably high on/off photocurrent ratio in response to a 532 nm Nd:YAG laser light was found. As the size of the particle (pea) increases, the corresponding spectra are red-shifted. In addition, morphological changes of the peas lead to a distinct spectral response. The results may usher in the diverse applications in optoelectronics and biosensing devices with peapod nanostructures.

Constricted nanowire with stabilized magnetic domain wall

International Nuclear Information System (INIS)

Sbiaa, R.; Al Bahri, M.

2016-01-01

Domain wall (DW)-based magnetic memory offers the possibility for increasing the storage capacity. However, stability of DW remains the major drawback of this scheme. In this letter, we propose a stepped nanowire for pinning DW in a desirable position. From micromagnetic simulation, the proposed design applied to in-plane magnetic anisotropy materials shows that by adjusting the nanowire step size and its width it is possible to stabilize DW for a desirable current density range. In contrast, only a movement of DW could be seen for conventional nanowire. An extension to a multi-stepped nanowire could be used for multi-bit per cell magnetic memory. - Highlights: • A stepped nanowire is proposed to pin domain wall in desired position. • The new structure can be made by a simple off set of two single nanowires. • The critical current for moving domain wall from one state to the other could be tuned by adjusting the geometry of the device. • The device could be used for multi-bit per cell memory by extending the steps in the device.

Perspectives of single cast nanowires technology

International Nuclear Information System (INIS)

Ioisher, Anatolii; Badinter, Efim; Postolache, Vitalie; Leporda, Nicolae; Tiginyanu, Ion; Monaico, Eduard

2011-01-01

The paper is dedicated to production potential of glass-coated cast nanowire with metal-, semimetal- and semiconductor-based cores by means of Taylor-Ulitovsky method. Criteria of melted core-formative material penetration into a drawing capillary were analyzed. Theoretical preconditions of the reduction of cast microwire diameter up to nano-dimensions of core are reviewed and an improved method of cast nanowire manufacturing is proposed. Correctness of conclusions was experimentally proved and laboratory samples of micro- and nano-wires with core diameter of about 200-300 nanometers were produced, even in case of materials with poor adhesion.

Multi-spectral optical absorption in substrate-free nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Zhang, Junpeng; Chia, Andrew; Boulanger, Jonathan; LaPierre, Ray, E-mail: lapierr@mcmaster.ca [Department of Engineering Physics, McMaster University, 1280 Main St. West, Hamilton, Ontario L8S 4L7 (Canada); Dhindsa, Navneet; Khodadad, Iman; Saini, Simarjeet [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada)

2014-09-22

A method is presented of fabricating gallium arsenide (GaAs) nanowire arrays of controlled diameter and period by reactive ion etching of a GaAs substrate containing an indium gallium arsenide (InGaP) etch stop layer, allowing the precise nanowire length to be controlled. The substrate is subsequently removed by selective etching, using the same InGaP etch stop layer, to create a substrate-free GaAs nanowire array. The optical absorptance of the nanowire array was then directly measured without absorption from a substrate. We directly observe absorptance spectra that can be tuned by the nanowire diameter, as explained with rigorous coupled wave analysis. These results illustrate strong optical absorption suitable for nanowire-based solar cells and multi-spectral absorption for wavelength discriminating photodetectors. The solar-weighted absorptance above the bandgap of GaAs was 94% for a nanowire surface coverage of only 15%.

Threshold switching uniformity in In2Se3 nanowire-based phase change memory

International Nuclear Information System (INIS)

Chen Jian; Du Gang; Liu Xiao-Yan

2015-01-01

The uniformity of threshold voltage and threshold current in the In 2 Se 3 nanowire-based phase change memory (PCM) devices is investigated. Based on the trap-limited transport model, amorphous layer thickness, trap density, and trap depth are considered to clarify their influences upon the threshold voltage and threshold current through simulations. (paper)

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

KAUST Repository

Heo, Junseok

2013-10-01

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

Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

International Nuclear Information System (INIS)

Zhang, Yanlin; Liu, Peihong; Wu, Honghai

2015-01-01

Highlights: • A facile hydrothermal route to synthesize N, S-codoped TiO 2 nanowires. • The codoped TiO 2 nanowires have TiO 2 (B) and anatase phase. • The significant shift of the optical absorption edge toward the visible region. • The photocatalyst showed high photocatalytic activity for atrazine. - Abstract: One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO 2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV–vis absorption spectrum. The incorporation of N and S into TiO 2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO 2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO 2 nanoparticles and S-doped TiO 2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron–hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C

Validation of hospital register-based diagnosis of Parkinson's disease

DEFF Research Database (Denmark)

Wermuth, Lene; Lassen, Christina Funch; Himmerslev, Liselotte

2012-01-01

Denmark has a long-standing tradition of maintaining one of the world's largest health science specialized register data bases as the National Hospital Register (NHR). To estimate the prevalence and incidence of diseases, the correctness of the diagnoses recorded is critical. Parkinson's disease...... (PD) is a neurodegenerative disorder and only 75-80% of patients with parkinsonism will have idiopathic PD (iPD). It is necessary to follow patients in order to determine if some of them will develop other neurodegenerative diseases and a one-time-only diagnostic code for iPD reported in the register...

Functionalised Silver Nanowire Structures

International Nuclear Information System (INIS)

Andrew, Piers; Ilie, Adelina

2007-01-01

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

Understanding the vapor-liquid-solid growth and composition of ternary III-V nanowires and nanowire heterostructures

Science.gov (United States)

Dubrovskii, V. G.

2017-11-01

Based on the recent achievements in vapor-liquid-solid (VLS) synthesis, characterization and modeling of ternary III-V nanowires and axial heterostructures within such nanowires, we try to understand the major trends in their compositional evolution from a general theoretical perspective. Clearly, the VLS growth of ternary materials is much more complex than in standard vapor-solid epitaxy techniques, and even maintaining the necessary control over the composition of steady-state ternary nanowires is far from straightforward. On the other hand, VLS nanowires offer otherwise unattainable material combinations without introducing structural defects and hence are very promising for next-generation optoelectronic devices, in particular those integrated with a silicon electronic platform. In this review, we consider two main problems. First, we show how and by means of which parameters the steady-state composition of Au-catalyzed or self-catalyzed ternary III-V nanowires can be tuned to a desired value and why it is generally different from the vapor composition. Second, we present some experimental data and modeling results for the interfacial abruptness across axial nanowire heterostructures, both in Au-catalyzed and self-catalyzed VLS growth methods. Refined modeling allows us to formulate some general growth recipes for suppressing the unwanted reservoir effect in the droplet and sharpening the nanowire heterojunctions. We consider and refine two approaches developed to date, namely the regular crystallization model for a liquid alloy with a critical size of only one III-V pair at high supersaturations or classical binary nucleation theory with a macroscopic critical nucleus at modest supersaturations.

Location deterministic biosensing from quantum-dot-nanowire assemblies

International Nuclear Information System (INIS)

Liu, Chao; Kim, Kwanoh; Fan, D. L.

2014-01-01

Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices.

The effects of the impurity distribution on the electrical and optical properties of Cr2+:ZnSe nanowires: First-principles study

Directory of Open Access Journals (Sweden)

Shenyu Dai

2018-03-01

Full Text Available The structural, electrical and mid-infrared optical properties of wurtzite structured ZnSe nanowires with different Chromium impurity distribution are investigated using first-principles calculation based on density-functional theory (DFT. The formation energies have been calculated to study the relative stabilities of different Cr doping positions. It is shown that when the Cr doping position shifted from the center to the edge, the splitting energy between 5T2 and 5E levels of Cr d-orbitals is decreased and a redshift is observed in the calculated infrared absorption spectra. A probable reason for these effects of the impurity distribution is discussed. Keywords: First-principles, Nanowires, Impurity distribution, Cr-doped ZnSe

Topological insulator nanowires and nanowire hetero-junctions

Science.gov (United States)

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

2014-03-01

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

Nanowire structures and electrical devices

Science.gov (United States)

Bezryadin, Alexey; Remeika, Mikas

2010-07-06

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

Fabrication of multilayer nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-06

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

Fabrication of multilayer nanowires

International Nuclear Information System (INIS)

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

2016-01-01

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

High mobility ZnO nanowires for terahertz detection applications

International Nuclear Information System (INIS)

Liu, Huiqiang; Peng, Rufang; Chu, Shijin; Chu, Sheng

2014-01-01

An oxide nanowire material was utilized for terahertz detection purpose. High quality ZnO nanowires were synthesized and field-effect transistors were fabricated. Electrical transport measurements demonstrated the nanowire with good transfer characteristics and fairly high electron mobility. It is shown that ZnO nanowires can be used as building blocks for the realization of terahertz detectors based on a one-dimensional plasmon detection configuration. Clear terahertz wave (∼0.3 THz) induced photovoltages were obtained at room temperature with varying incidence intensities. Further analysis showed that the terahertz photoresponse is closely related to the high electron mobility of the ZnO nanowire sample, which suggests that oxide nanoelectronics may find useful terahertz applications.

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.

Purcell effect for finite-length metal-coated and metal nanowires

DEFF Research Database (Denmark)

Filonenko, Konstantin V.; Willatzen, Morten; Bordo, Vladimir G.

2014-01-01

We investigate the modification (enhancement and suppression) of the spontaneous emission rate of a dipole emitter in two configurations: inside a finite-length semiconductor nanowire surrounded by bulk metal and in the vicinity of a finite metal nanowire. Our analysis is based on a first......-principle approach, which is reduced to a seminumeric one in the limit of large nanowire aspect ratios. The numerical calculations are carried out for an emitter in a GaAs nanowire embedded in Ag or Au and for that nearby an Ag or Au nanowire in vacuum or dielectric. We consider in detail the Purcell and β factors...

Copper vanadate nanowires-based MIS capacitors: Synthesis, characterization, and their electrical charge storage applications

KAUST Repository

Shahid, Muhammad

2013-07-14

Copper vanadate (CVO) nanowires were grown on Si/SiO2 substrates by thermal annealing technique. A thin film of a CVO precursor at 550 C under an ambient atmosphere could also be prepared. The electrical properties of the nanowires embedded in the dielectrical layer were examined by capacitance-voltage (C-V) measurements. The C-V curves for Au/CVO nanowires embedded in an hafnium oxide layer/SiO2/p-Si capacitor at 298 K showed a clockwise hysteresis loop when the gate bias was swept cyclically. The hysteresis characteristics were studied further at different frequencies, which clearly indicated that the traps in the nanowires have a large charging-discharging time and thus the as-synthesized nanowires can be utilized for electrical charge storage devices. © 2013 Springer Science+Business Media Dordrecht.

Copper vanadate nanowires-based MIS capacitors: synthesis, characterization, and their electrical charge storage applications

Energy Technology Data Exchange (ETDEWEB)

Shahid, Muhammad, E-mail: shahid@skku.edu [King Abdullah University of Science and Technology, Material Science and Engineering (Saudi Arabia); Nafady, Ayman [King Saud University, Department of Chemistry, College of Science (Saudi Arabia); Shakir, Imran; Rana, Usman Ali; Sarfraz, Mansoor [King Saud University, Sustainable Energy Technologies (SET) Center, College of Engineering (Saudi Arabia); Warsi, Muhammad Farooq [The Islamia University of Bahawalpur, Department of Chemistry (Pakistan); Hussain, Rafaqat [Universiti Teknologi Malaysia, Ibnu Sina Institute for Fundamental Science Studies (Malaysia); Ashiq, Muhammad Naeem [Bahauddin Zakaryia University, Institute of Chemical Sciences (Pakistan)

2013-08-15

Copper vanadate (CVO) nanowires were grown on Si/SiO{sub 2} substrates by thermal annealing technique. A thin film of a CVO precursor at 550 Degree-Sign C under an ambient atmosphere could also be prepared. The electrical properties of the nanowires embedded in the dielectrical layer were examined by capacitance-voltage (C-V) measurements. The C-V curves for Au/CVO nanowires embedded in an hafnium oxide layer/SiO{sub 2}/p-Si capacitor at 298 K showed a clockwise hysteresis loop when the gate bias was swept cyclically. The hysteresis characteristics were studied further at different frequencies, which clearly indicated that the traps in the nanowires have a large charging-discharging time and thus the as-synthesized nanowires can be utilized for electrical charge storage devices.

Copper vanadate nanowires-based MIS capacitors: Synthesis, characterization, and their electrical charge storage applications

KAUST Repository

Shahid, Muhammad; Nafady, Ayman; Shakir, Imran; Rana, Usman Ali; Sarfraz, Mansoor M.; Warsi, Muhammad Farooq; Hussain, Rafaqat; Ashiq, Muhammad Naeem

2013-01-01

Copper vanadate (CVO) nanowires were grown on Si/SiO2 substrates by thermal annealing technique. A thin film of a CVO precursor at 550 C under an ambient atmosphere could also be prepared. The electrical properties of the nanowires embedded in the dielectrical layer were examined by capacitance-voltage (C-V) measurements. The C-V curves for Au/CVO nanowires embedded in an hafnium oxide layer/SiO2/p-Si capacitor at 298 K showed a clockwise hysteresis loop when the gate bias was swept cyclically. The hysteresis characteristics were studied further at different frequencies, which clearly indicated that the traps in the nanowires have a large charging-discharging time and thus the as-synthesized nanowires can be utilized for electrical charge storage devices. © 2013 Springer Science+Business Media Dordrecht.

Thermoelectric Power Factor Limit of a 1D Nanowire

Science.gov (United States)

Chen, I.-Ju; Burke, Adam; Svilans, Artis; Linke, Heiner; Thelander, Claes

2018-04-01

In the past decade, there has been significant interest in the potentially advantageous thermoelectric properties of one-dimensional (1D) nanowires, but it has been challenging to find high thermoelectric power factors based on 1D effects in practice. Here we point out that there is an upper limit to the thermoelectric power factor of nonballistic 1D nanowires, as a consequence of the recently established quantum bound of thermoelectric power output. We experimentally test this limit in quasiballistic InAs nanowires by extracting the maximum power factor of the first 1D subband through I -V characterization, finding that the measured maximum power factors conform to the theoretical limit. The established limit allows the prediction of the achievable power factor of a specific nanowire material system with 1D electronic transport based on the nanowire dimension and mean free path. The power factor of state-of-the-art semiconductor nanowires with small cross section and high crystal quality can be expected to be highly competitive (on the order of mW /m K2 ) at low temperatures. However, they have no clear advantage over bulk materials at, or above, room temperature.

Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

International Nuclear Information System (INIS)

Tam, Phuong Dinh; Thang, Cao Xuan

2016-01-01

This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO 2 nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO 2 nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) 6 ] 3−/4− as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10 2 CFU/mL to 1.0 × 10 4 CFU/mL. The detection limit of the immunosensor was 1.0 × 10 2 CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL −1 . Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10 2 CFU/mL to 1.0 × 10 4 CFU/mL. • The detection limit of the immunosensor was 1.0 × 10 2 CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL −1 .

Guiding modes of semi-infinite nanowire and their dispersion character

International Nuclear Information System (INIS)

Sun, Yuming; Su, Yuehua; Dai, Zhenhong; Wang, Weitian

2014-01-01

Conventionally, the optical properties of finite semiconductor nanowires have been understood and explained in terms of an infinite nanowire. This work describes completely different photonic modes for a semi-finite nanowire based on a rigorous theoretical method, and the implications for the finite one. First, the special eigenvalue problem charactered by the end results in a distinctive mode spectrum for the semi-infinite dielectric nanowire. Meanwhile, the results show hybrid degenerate modes away from cutoff frequency, and transverse electric–transverse magnetic (TE–TM) degeneracy. Second, accompanying a different mode spectrum, a semi-finite nanowire also shows a distinctive dispersion relation compared to an infinite nanowire. Taking a semi-infinite, ZnO nanowire as an example, we find that the ℏω−k z space is not continuous in the interested photon energy window, implying that there is no uniform polariton dispersion relation for semi-infinite nanowire. Our method is shown correct through a field-reconstruction for a thin ZnO nanowire (55 nm in radius) and position determination of FP modes for a ZnO nanowire (200 nm in diameter). The results are of great significance to correctly understand the guiding and lasing mechanisms of semiconductor nanowires. (paper)

Study of optical absorbance in porous silicon nanowires for photovoltaic applications

KAUST Repository

Charrier, Joël

2013-10-01

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

Quantification of nanowire uptake by live cells

KAUST Repository

Margineanu, Michael B.

2015-05-01

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

Nanowire Electrodes for Advanced Lithium Batteries

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-27

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

Nanowire Electrodes for Advanced Lithium Batteries

Directory of Open Access Journals (Sweden)

Lei eHuang

2014-10-01

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

Nanowire Electrodes for Advanced Lithium Batteries

International Nuclear Information System (INIS)

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

2014-01-01

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

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

DEFF Research Database (Denmark)

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

2012-01-01

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

Precise Placement of Metallic Nanowires on a Substrate by Localized Electric Fields and Inter-Nanowire Electrostatic Interaction

Directory of Open Access Journals (Sweden)

U Hyeok Choi

2017-10-01

Full Text Available Placing nanowires at the predetermined locations on a substrate represents one of the significant hurdles to be tackled for realization of heterogeneous nanowire systems. Here, we demonstrate spatially-controlled assembly of a single nanowire at the photolithographically recessed region at the electrode gap with high integration yield (~90%. Two popular routes, such as protruding electrode tips and recessed wells, for spatially-controlled nanowire alignment, are compared to investigate long-range dielectrophoretic nanowire attraction and short-range nanowire-nanowire electrostatic interaction for determining the final alignment of attracted nanowires. Furthermore, the post-assembly process has been developed and tested to make a robust electrical contact to the assembled nanowires, which removes any misaligned ones and connects the nanowires to the underlying electrodes of circuit.

Shear-driven phase transformation in silicon nanowires.

Science.gov (United States)

Vincent, L; Djomani, D; Fakfakh, M; Renard, C; Belier, B; Bouchier, D; Patriarche, G

2018-03-23

We report on an unprecedented formation of allotrope heterostructured Si nanowires by plastic deformation based on applied radial compressive stresses inside a surrounding matrix. Si nanowires with a standard diamond structure (3C) undergo a phase transformation toward the hexagonal 2H-allotrope. The transformation is thermally activated above 500 °C and is clearly driven by a shear-stress relief occurring in parallel shear bands lying on {115} planes. We have studied the influence of temperature and axial orientation of nanowires. The observations are consistent with a martensitic phase transformation, but the finding leads to clear evidence of a different mechanism of deformation-induced phase transformation in Si nanowires with respect to their bulk counterpart. Our process provides a route to study shear-driven phase transformation at the nanoscale in Si.

Growth and Raman spectroscopy studies of gold-free catalyzed semiconductor nanowires

Energy Technology Data Exchange (ETDEWEB)

Zardo, Ilaria

2010-12-15

, enabled us to address the variation of the intensity of the scattered radiation along the nanowire length to the variation of the crystalline fraction. As well, the shift in frequency of the mode related to the crystalline Ge was attributed to phonon confinement effects. Spatially resolved Raman spectroscopy experiments were realized on single GaAs nanowires. Polarization dependent Raman scattering experiments enabled us to determine the Raman selection rules for zinc-blende GaAs nanowires. They were found to be modified with respect to the bulk. A component of the scattered light with respect to bulk GaAs is suppressed, due to the dielectric mismatch of a cylinder of nanoscale dimensions. Spatially resolved Raman spectroscopy experiments were realized on single zinc- blende/wurtzite GaAs nanowires, with different wurtzite content. The Raman spectrum of wurtzite GaAs was measured for the first time and the symmetry of the corresponding modes was determined by polarization dependent scattering experiments. The E{sub 1} - A{sub 1} splitting due to anisotropy of the crystal in wurtzite GaAs nanowires was found. The presence of strain along the zinc-blende/wurtzite nanowires was studied. Light scattering experiments on zinc-blende GaAs nanowires under hydrostatic pressure up to 20 GPa were realized with the use of a diamond anvil cell. The resonance profile of the 2LO mode suggests a stronger Froehlich coupling. The Grueneisen parameters were also found to be different from those obtained from bulk GaAs. Finally, there is evidence for a structural transition for P>16 GPa. (orig.)

Effective immobilization of DNA for development of polypyrrole nanowires based biosensor

Energy Technology Data Exchange (ETDEWEB)

Tran, Thi Luyen; Chu, Thi Xuan, E-mail: xuan@itims.edu.vn; Huynh, Dang Chinh; Pham, Duc Thanh; Luu, Thi Hoai Thuong; Mai, Anh Tuan, E-mail: tuan.maianh@hust.edu.vn

2014-09-30

Highlights: • Effective technique to immobilize probe DNA to the conducting polymer Polypyrrole nanowires (PPy NWs). • The PPy-NWs were electrochemically synthesized on the surface of the Pt electrodes using gelatin as the soft mold. • The DNA probe sequences were immobilized easily on the PPy NWs/Pt electrode using the adsorption method. • The DNA sensor has a low detection limit. - Abstract: This paper reports an easy technique for immobilization of the DNA to the conducting polymer polypyrrole nanowires (PPy NWs). The nanowires were electrochemically synthesized on the surface of working electrode in the presence of gelatin as a soft mold. The structure of obtained PPy NWs was investigated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy and Surface Enhanced Raman Spectroscopy (SERS). The DNA strands were directly immobilized on the PPy NWs. The amino groups at the up-end of the PPy nanowires facilitate the linkage with the phosphate groups of the probe DNA. The DNA immobilization and hybridization were characterized by Electrochemical Impedance Spectroscopy (EIS). The initial results show that the sensor responses to 10 pM of DNA sequence in the solution.

Synthesis and Growth Mechanism of Ni Nanotubes and Nanowires

Directory of Open Access Journals (Sweden)

Wang Yiqian

2009-01-01

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

Broadband infrared photoluminescence in silicon nanowires with high density stacking faults.

Science.gov (United States)

Li, Yang; Liu, Zhihong; Lu, Xiaoxiang; Su, Zhihua; Wang, Yanan; Liu, Rui; Wang, Dunwei; Jian, Jie; Lee, Joon Hwan; Wang, Haiyan; Yu, Qingkai; Bao, Jiming

2015-02-07

Making silicon an efficient light-emitting material is an important goal of silicon photonics. Here we report the observation of broadband sub-bandgap photoluminescence in silicon nanowires with a high density of stacking faults. The photoluminescence becomes stronger and exhibits a blue shift under higher laser powers. The super-linear dependence on excitation intensity indicates a strong competition between radiative and defect-related non-radiative channels, and the spectral blue shift is ascribed to the band filling effect in the heterostructures of wurtzite silicon and cubic silicon created by stacking faults.

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.

Shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowires

Science.gov (United States)

Wen, Feng; Dillen, David C.; Kim, Kyounghwan; Tutuc, Emanuel

2017-06-01

We investigate the shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowire heterostructures grown using a combination of a vapor-liquid-solid (VLS) growth mechanism for the core, followed by in-situ epitaxial shell growth using ultra-high vacuum chemical vapor deposition. Cross-sectional transmission electron microscopy reveals that the VLS growth yields cylindrical Ge, and Si nanowire cores grown along the ⟨111⟩, and ⟨110⟩ or ⟨112⟩ directions, respectively. A hexagonal cross-sectional morphology is observed for Ge-SixGe1-x core-shell nanowires terminated by six {112} facets. Two distinct morphologies are observed for Si-SixGe1-x core-shell nanowires that are either terminated by four {111} and two {100} planes associated with the ⟨110⟩ growth direction or four {113} and two {111} planes associated with the ⟨112⟩ growth direction. We show that the Raman spectra of Si- SixGe1-x are correlated with the shell morphology thanks to epitaxial growth-induced strain, with the core Si-Si mode showing a larger red shift in ⟨112⟩ core-shell nanowires compared to their ⟨110⟩ counterparts. We compare the Si-Si Raman mode value with calculations based on a continuum elasticity model coupled with the lattice dynamic theory.

Self-Catalyzed Growth and Characterization of In(As)P Nanowires on InP(111)B Using Metal-Organic Chemical Vapor Deposition.

Science.gov (United States)

Park, Jeung Hun; Pozuelo, Marta; Setiawan, Bunga P D; Chung, Choong-Heui

2016-12-01

We report the growth of vertical -oriented InAs x P1-x (0.11 ≤ x ≤ 0.27) nanowires via metal-organic chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates at 375 °C. Trimethylindium, tertiarybutylphosphine, and tertiarybutylarsine are used as the precursors, corresponding to P/In and As/In molar ratios of 29 and 0.01, respectively. The as-grown nanowire growth morphologies, crystallinity, composition, and optical characteristics are determined using a combination of scanning and transmission electron microscopies, electron diffraction, and X-ray photoelectron, energy dispersive X-ray, and Raman spectroscopies. We find that the InAs x P1-x nanowires are tapered with narrow tops, wider bases, and In-rich In-As alloy tips, characteristic of vapor-liquid-solid process. The wires exhibit a mixture of zinc blende and wurtzite crystal structures and a high density of structural defects such as stacking faults and twins. Our results suggest that the incorporation of As into InP wires decreases with increasing substrate temperature. The Raman spectra obtained from the In(As)P nanowires reveal a red-shift and lower intensity of longitudinal optical mode relative to both InP nanowires and InP(111)B bulk, due to the incorporation of As into the InP matrix.

Register-based studies of cancer screening effects

DEFF Research Database (Denmark)

Von Euler-Chelpin, My; Lynge, Elsebeth; Rebolj, Matejka

2011-01-01

INTRODUCTION: There are two organised cancer screening programmes in Denmark, against cervical and breast cancers. The aim with this study was to give an overview of the available register-based research regarding these two programmes, to demonstrate the usefulness of data from the national regis...

Anomalous magnetic properties of 7 nm single-crystal Co3O4 nanowires

Science.gov (United States)

Lv, Ping; Zhang, Yan; Xu, Rui; Nie, Jia-Cai; He, Lin

2012-01-01

We present a study of magnetic properties of single-crystal Co3O4 nanowires with diameter about 7 nm. The nanowires expose (111) planes composed of plenty of Co3+ cations and exhibit two order temperatures at 56 K (TN of wire cores) and 73 K (order temperature of wire shells), which are far above TN = 40 K of bulk Co3O4. This novel behavior is attributed to symmetry breaking of surface Co3+ cations and magnetic proximity effect. The nanowire shells show macroscopic residual magnetic moments. Cooling in a magnetic field, a fraction of the residual moments are tightly pinned to the antiferromagnetic lattice, which results in an obvious horizontal and vertical shift of hysteresis loop. Our experiment demonstrates that the exchange bias field HE and the pinned magnetic moments Mpin follow a simple expression HE = aMpin with a a constant.

Three-dimensional electrodes for dye-sensitized solar cells: synthesis of indium-tin-oxide nanowire arrays and ITO/TiO2 core-shell nanowire arrays by electrophoretic deposition

International Nuclear Information System (INIS)

Wang, H-W; Ting, C-F; Hung, M-K; Chiou, C-H; Liu, Y-L; Liu Zongwen; Ratinac, Kyle R; Ringer, Simon P

2009-01-01

Dye-sensitized solar cells (DSSCs) show promise as a cheaper alternative to silicon-based photovoltaics for specialized applications, provided conversion efficiency can be maximized and production costs minimized. This study demonstrates that arrays of nanowires can be formed by wet-chemical methods for use as three-dimensional (3D) electrodes in DSSCs, thereby improving photoelectric conversion efficiency. Two approaches were employed to create the arrays of ITO (indium-tin-oxide) nanowires or arrays of ITO/TiO 2 core-shell nanowires; both methods were based on electrophoretic deposition (EPD) within a polycarbonate template. The 3D electrodes for solar cells were constructed by using a doctor-blade for coating TiO 2 layers onto the ITO or ITO/TiO 2 nanowire arrays. A photoelectric conversion efficiency as high as 4.3% was achieved in the DSSCs made from ITO nanowires; this performance was better than that of ITO/TiO 2 core-shell nanowires or pristine TiO 2 films. Cyclic voltammetry confirmed that the reaction current was significantly enhanced when a 3D ITO-nanowire electrode was used. Better separation of charge carriers and improved charge transport, due to the enlarged interfacial area, are thought to be the major advantages of using 3D nanowire electrodes for the optimization of DSSCs.

Piezoresistive Pressure Sensor Based on Synergistical Innerconnect Polyvinyl Alcohol Nanowires/Wrinkled Graphene Film.

Science.gov (United States)

Liu, Weijie; Liu, Nishuang; Yue, Yang; Rao, Jiangyu; Cheng, Feng; Su, Jun; Liu, Zhitian; Gao, Yihua

2018-04-01

Piezoresistive sensor is a promising pressure sensor due to its attractive advantages including uncomplicated signal collection, simple manufacture, economical and practical characteristics. Here, a flexible and highly sensitive pressure sensor based on wrinkled graphene film (WGF)/innerconnected polyvinyl alcohol (PVA) nanowires/interdigital electrodes is fabricated. Due to the synergistic effect between WGF and innerconnected PVA nanowires, the as-prepared pressure sensor realizes a high sensitivity of 28.34 kPa -1 . In addition, the device is able to discern lightweight rice about 22.4 mg (≈2.24 Pa) and shows excellent durability and reliability after 6000 repeated loading and unloading cycles. What is more, the device can detect subtle pulse beat and monitor various human movement behaviors in real-time. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

Energy Technology Data Exchange (ETDEWEB)

Tam, Phuong Dinh, E-mail: phuongdinhtam@gmail.com; Thang, Cao Xuan, E-mail: thang.caoxuan@hust.edu.vn

2016-01-01

This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO{sub 2} nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO{sub 2} nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) {sub 6}] {sup 3−/4−} as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL{sup −1}. Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. • The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL{sup −1}.

Fabrication and testing of a CoNiCu/Cu CPP-GMR nanowire-based microfluidic biosensor

International Nuclear Information System (INIS)

Bellamkonda, Ramya; John, Tom; Mathew, Bobby; DeCoster, Mark; Hegab, Hisham; Davis, Despina

2010-01-01

Giant magneto resistance (GMR)-based microfluidic biosensors are used in applications involving the detection, analysis, enumeration and characterization of magnetic nano-particles attached to biological mediums such as antibodies and DNA. Here we introduce a novel multilayered CoNiCu/Cu nanowire GMR-based microfluidic biosensor. The current perpendicular to the plane of multilayers (CPP)-nanowires GMR was used as the core sensing material in the biosensor which responds to magnetic fields depending on the concentration and the flow velocity of bio-nano-magnetic fluids. The device was tested with different control solutions such as DI-water, mineral oil, phosphate buffered saline (PBS), ferrofluid, polystyrene superparamagnetic beads (PSB) and Dynabeads sheep anti-rabbit IgG. The nanowire array resistance decreased with an increase in the ferrofluid concentration, and a maximum 15.8% relative GMR was observed for the undiluted ferrofluid. The sensor was also responding differently to various ferrofluid flow rates. The GMR device showed variation in the output signal when the PSB and Dynabeads of different dilutions were pumped through it. When the tests were performed with pulsing potentials (150 mV and 200 mV), an increased GMR response was identified at higher voltages for PSB and Dynabeads sheep anti-rabbit IgG.

Electroless Fabrication of Cobalt Alloys Nanowires within Alumina Template

Directory of Open Access Journals (Sweden)

Nazila Dadvand

2007-01-01

Full Text Available A new method of nanowire fabrication based on electroless deposition process is described. The method is novel compared to the current electroless procedure used in making nanowires as it involves growing nanowires from the bottom up. The length of the nanowires was controlled at will simply by adjusting the deposition time. The nanowires were fabricated within the nanopores of an alumina template. It was accomplished by coating one side of the template by a thin layer of palladium in order to activate the electroless deposition within the nanopores from bottom up. However, prior to electroless deposition process, the template was pretreated with a suitable wetting agent in order to facilitate the penetration of the plating solution through the pores. As well, the electroless deposition process combined with oblique metal evaporation process within a prestructured silicon wafer was used in order to fabricate long nanowires along one side of the grooves within the wafer.

From nanodiamond to nanowires.

Energy Technology Data Exchange (ETDEWEB)

Barnard, A.; Materials Science Division

2005-01-01

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

Electrodeposition of Metal on GaAs Nanowires

Science.gov (United States)

Liu, Chao; Einabad, Omid; Watkins, Simon; Kavanagh, Karen

2010-10-01

Copper (Cu) electrical contacts to freestanding gallium arsenide (GaAs) nanowires have been fabricated via electrodeposition. The nanowires are zincblende (111) oriented grown epitaxially on n-type Si-doped GaAs (111)B substrates by gold-catalyzed Vapor Liquid Solid (VLS) growth in a metal organic vapour phase epitaxy (MOVPE) reactor. The epitaxial electrodeposition process, based on previous work with bulk GaAs substrates, consists of a substrate oxide pre-etch in dilute ammonium-hydroxide carried out prior to galvanostatic electrodeposition in a pure Cu sulphate aqueous electrolyte at 20-60^oC. For GaAs nanowires, we find that Cu or Fe has a preference for growth on the gold catalyst avoiding the sidewalls. After removing gold, both metals still prefer to grow only on top of the nanowire, which has the largest potential field.

Dynamic current susceptibility as a probe of Majorana bound states in nanowire-based Josephson junctions

Science.gov (United States)

Trif, Mircea; Dmytruk, Olesia; Bouchiat, Hélène; Aguado, Ramón; Simon, Pascal

2018-02-01

We theoretically study a Josephson junction based on a semiconducting nanowire subject to a time-dependent flux bias. We establish a general density-matrix approach for the dynamical response of the Majorana junction and calculate the resulting flux-dependent susceptibility using both microscopic and effective low-energy descriptions for the nanowire. We find that the diagonal component of the susceptibility, associated with the dynamics of the Majorana state populations, dominates over the standard Kubo contribution for a wide range of experimentally relevant parameters. The diagonal term, explored, in this Rapid Communication, in the context of Majorana physics, allows probing accurately the presence of Majorana bound states in the junction.

Methods of fabricating nanostructures and nanowires and devices fabricated therefrom

Energy Technology Data Exchange (ETDEWEB)

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

2018-01-30

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

Ambient template synthesis of multiferroic MnWO4 nanowires and nanowire arrays

International Nuclear Information System (INIS)

Zhou Hongjun; Yiu Yuen; Aronson, M.C.; Wong, Stanislaus S.

2008-01-01

The current report describes the systematic synthesis of polycrystalline, multiferroic MnWO 4 nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions. We were able to synthesize nanowires measuring 55±10, 100±20, and 260±40 nm in diameter, respectively, with lengths ranging in the microns. Extensive characterization of as-prepared samples has been performed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy. Magnetic behavior in these systems was also probed. - Graphical abstract: Systematic synthesis of crystalline, multiferroic MnWO4 nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions

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

Optimizing the top profile of a nanowire for maximum forward emission

Institute of Scientific and Technical Information of China (English)

Wang Dong-Lin; Yu Zhong-Yuan; Liu Yu-Min; Guo Xiao-Tao; Cao Gui; Feng Hao

2011-01-01

The optimal top structure of a nanowire quantum emitter single photon source is significant in improving performance.Based on the axial symmetry of a cylindrical nanowire,this paper optimizes the top profile of a nanowire for the maximum forward emission by combining the geometry projection method and the finite element method.The results indicate that the nanowire with a cambered top has the stronger emission in the forward direction,which is helpful to improve the photon collection efficiency.

Enhanced light scattering of the forbidden longitudinal optical phonon mode studied by micro-Raman spectroscopy on single InN nanowires

International Nuclear Information System (INIS)

Schaefer-Nolte, E O; Stoica, T; Gotschke, T; Limbach, F A; Gruetzmacher, D; Calarco, R; Sutter, E; Sutter, P

2010-01-01

In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E 2 phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

Enhanced Light Scattering of the Forbidden longitudinal Optical Phonon Mode Studied by Micro-Raman Spectroscopy on Single InN nanowires

International Nuclear Information System (INIS)

Sutter, E.; Schafer-Nolte, E.O.; Stoica, T.; Gotschke, T.; Limbach, F.A.; Sutter, P.; Grutzmacher, D.; Calarco, R.

2010-01-01

In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E2 phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

Enhanced light scattering of the forbidden longitudinal optical phonon mode studied by micro-Raman spectroscopy on single InN nanowires.

Science.gov (United States)

Schäfer-Nolte, E O; Stoica, T; Gotschke, T; Limbach, F A; Sutter, E; Sutter, P; Grützmacher, D; Calarco, R

2010-08-06

In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E(2) phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

KAUST Repository

Shen, Youde; Chen, Renjie; Yu, Xuechao; Wang, Qijie; Jungjohann, Katherine L.; Dayeh, Shadi A.; Wu, Tao

2016-01-01

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices. © 2016 American Chemical Society.

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

KAUST Repository

Shen, Youde

2016-06-02

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices. © 2016 American Chemical Society.

Growth Mechanism of Nanowires: Ternary Chalcogenides

Science.gov (United States)

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

2016-01-01

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

Vertically integrated logic circuits constructed using ZnO-nanowire-based field-effect transistors on plastic substrates.

Science.gov (United States)

Kang, Jeongmin; Moon, Taeho; Jeon, Youngin; Kim, Hoyoung; Kim, Sangsig

2013-05-01

ZnO-nanowire-based logic circuits were constructed by the vertical integration of multilayered field-effect transistors (FETs) on plastic substrates. ZnO nanowires with an average diameter of -100 nm were synthesized by thermal chemical vapor deposition for use as the channel material in FETs. The ZnO-based FETs exhibited a high I(ON)/I(OFF) of > 10(6), with the characteristic of n-type depletion modes. For vertically integrated logic circuits, three multilayer FETs were sequentially prepared. The stacked FETs were connected in series via electrodes, and C-PVPs were used for the layer-isolation material. The NOT and NAND gates exhibited large logic-swing values of -93%. These results demonstrate the feasibility of three dimensional flexible logic circuits.

Looking into meta-atoms of plasmonic nanowire metamaterial

KAUST Repository

Tsai, Kuntong

2014-09-10

Nanowire-based plasmonic metamaterials exhibit many intriguing properties related to the hyperbolic dispersion, negative refraction, epsilon-near-zero behavior, strong Purcell effect, and nonlinearities. We have experimentally and numerically studied the electromagnetic modes of individual nanowires (meta-atoms) forming the metamaterial. High-resolution, scattering-type near-field optical microscopy has been used to visualize the intensity and phase of the modes. Numerical and analytical modeling of the mode structure is in agreement with the experimental observations and indicates the presence of the nonlocal response associated with cylindrical surface plasmons of nanowires.

Development of high efficient visible light-driven N, S-codoped TiO{sub 2} nanowires photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yanlin, E-mail: zhangyl@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Key Laboratory of Theoretical Chemistry of Environment Ministry of Education, South China Normal University, Guangzhou 510006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Liu, Peihong; Wu, Honghai [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China)

2015-02-15

Highlights: • A facile hydrothermal route to synthesize N, S-codoped TiO{sub 2} nanowires. • The codoped TiO{sub 2} nanowires have TiO{sub 2} (B) and anatase phase. • The significant shift of the optical absorption edge toward the visible region. • The photocatalyst showed high photocatalytic activity for atrazine. - Abstract: One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO{sub 2} nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV–vis absorption spectrum. The incorporation of N and S into TiO{sub 2} NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO{sub 2} nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO{sub 2} nanoparticles and S-doped TiO{sub 2} nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron–hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C.

Controlled Synthesis of Nanowire Assemblies by Ion-Track Template Electrodeposition

OpenAIRE

Rauber, Markus

2012-01-01

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

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

International Nuclear Information System (INIS)

He, Yan; Yu, Wangbing; Ouyang, Gang

2016-01-01

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

Piezo-Phototronic Enhanced UV Sensing Based on a Nanowire Photodetector Array.

Science.gov (United States)

Han, Xun; Du, Weiming; Yu, Ruomeng; Pan, Caofeng; Wang, Zhong Lin

2015-12-22

A large array of Schottky UV photodetectors (PDs) based on vertical aligned ZnO nanowires is achieved. By introducing the piezo-phototronic effect, the performance of the PD array is enhanced up to seven times in photoreponsivity, six times in sensitivity, and 2.8 times in detection limit. The UV PD array may have applications in optoelectronic systems, adaptive optical computing, and communication. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

DEFF Research Database (Denmark)

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

2013-01-01

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

Formation of crystalline InGaO₃(ZnO)n nanowires via the solid-phase diffusion process using a solution-based precursor.

Science.gov (United States)

Guo, Yujie; Van Bilzen, Bart; Locquet, Jean Pierre; Seo, Jin Won

2015-12-11

One-dimensional single crystalline InGaO3(ZnO)n (IGZO) nanostructures have great potential for various electrical and optical applications. This paper demonstrates for the first time, to our knowledge, a non-vacuum route for the synthesis of IGZO nanowires by annealing ZnO nanowires covered with solution-based IGZO precursor. This method results in nanowires with highly periodic IGZO superlattice structure. The phase transition of IGZO precursor during thermal treatment was systematically studied. Transmission electron microscopy studies reveal that the formation of the IGZO structure is driven by anisotropic inter-diffusion of In, Ga, and Zn atoms, and also by the crystallization of the IGZO precursor. Optical measurements using cathodoluminescence and UV-vis spectroscopy confirm that the nanowires consist of the IGZO compound with wide optical band gap and suppressed luminescence.

Quantum-confined nanowires as vehicles for enhanced electrical transport

International Nuclear Information System (INIS)

Mohammad, S Noor

2012-01-01

Electrical transport in semiconductor nanowires taking quantum confinement and dielectric confinement into account has been studied. A distinctly new route has been employed for the study. The fundamental science underlying the model is based on a relationship between the quantum confinement and the structural disorder of the nanowire surface. The role of surface energy and thermodynamic imbalance in nanowire structural disorder has been described. A model for the diameter dependence of energy bandgap of nanowires has been developed. Ionized impurity scattering, dislocation scattering and acoustic phonon scattering have been taken into account to study carrier mobility. A series of calculations on silicon nanowires show that carrier mobility in nanowires can be greatly enhanced by quantum confinement and dielectric confinement. The electron mobility can, for example, be a factor of 2–10 higher at room temperature than the mobility in a free-standing silicon nanowire. The calculated results agree well with almost all experimental and theoretical results available in the literature. They successfully explain experimental observations not understood before. The model is general and applicable to nanowires from all possible semiconductors. It is perhaps the first physical model highlighting the impact of both quantum confinement and dielectric confinement on carrier transport. It underscores the basic causes of thin, lowly doped nanowires in the temperature range 200 K ≤ T ≤ 500 K yielding very high carrier mobility. It suggests that the scattering by dislocations (stacking faults) can be very detrimental for carrier mobility. (paper)

Cu-Ni nanowire-based TiO{sub 2} hybrid for the dynamic photodegradation of acetaldehyde gas pollutant under visible light

Energy Technology Data Exchange (ETDEWEB)

Zhu, Shuying [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Xie, Xiaofeng, E-mail: xxfshcn@163.com [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Chen, Sheng-Chieh [College of Science and Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Tong, Shengrui [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Guanhong [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Pui, David Y.H. [College of Science and Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Sun, Jing [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2017-06-30

Graphical abstract: One-dimensional Cu-Ni bimetallic nanowires were introduced into TiO{sub 2}-based matrix to enhance their photocatalysis efficiency and expand their light absorption range. - Highlights: • Cu-Ni nanowire-based TiO{sub 2} hybrid photocatalyst. • One-dimensional electron pathways and surface plasmon resonance effects. • Dynamic photodegradation of acetaldehyde gas pollutant. - Abstract: One-dimensional bimetallic nanowires were introduced into TiO{sub 2}-based matrix to enhance their photocatalysis efficiency and expand their light absorption range in this work. Recently, metal nanowires have attracted many attention in photocatalyst research fields because of their favorable electronic transmission properties and especially in the aspect of surface plasmon resonance effects. Moreover, Cu-Ni bimetallic nanowires (Cu-Ni NWs) have shown better chemical stability than ordinary monometallic nanowires in our recent works. Interestingly, it has been found that Ni sleeves of the bimetallic nanowires also can modify the Schottky barrier of interface between TiO{sub 2} and metallic conductor, so that be beneficial to the separation of photogenerated carriers in the Cu-Ni/TiO{sub 2} network topology. Hence, a novel heterostructured photocatalyst composed of Cu-Ni NWs and TiO{sub 2} nanoparticles (NPs) was fabricated by one-step hydrolysis approach to explore its photocatalytic performance. TEM and EDX mapping images of this TiO{sub 2} NPs @Cu-Ni NWs (TCN) hybrid displayed that Cu-Ni NWs were wrapped by compact TiO{sub 2} layer and retained the one-dimensional structure in matrix. In experiments, the photocatalytic performance of the TCN nanocomposite was significantly enhanced comparing to pure TiO{sub 2}. Acetaldehyde, as a common gas pollutant in the environment, was employed to evaluate the photodegradation efficiency of a series of TCN nanocomposites under continuous feeding. The TCN exhibited excellent potodegradation performance, where the

Optical properties of photodetectors based on single GaN nanowires with a transparent graphene contact

Energy Technology Data Exchange (ETDEWEB)

Babichev, A. V., E-mail: A.Babichev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Zhang, H.; Guan, N. [University Paris Saclay, Institut d’Electronique Fondamentale, UMR 8622 CNRS (France); Egorov, A. Yu. [ITMO University (Russian Federation); Julien, F. H.; Messanvi, A. [University Paris Saclay, Institut d’Electronique Fondamentale, UMR 8622 CNRS (France); Durand, C.; Eymery, J. [University Grenoble Alpes (France); Tchernycheva, M. [University Paris Saclay, Institut d’Electronique Fondamentale, UMR 8622 CNRS (France)

2016-08-15

We report the fabrication and optical and electrical characterization of photodetectors for the UV spectral range based on single p–n junction nanowires with a transparent contact of a new type. The contact is based on CVD-grown (chemical-vapor deposition) graphene. The active region of the nitride nanowires contains a set of 30 radial In{sub 0.18}Ga{sub 0.82}N/GaN quantum wells. The structure is grown by metal-organic vaporphase epitaxy. The photodetectors are fabricated using electron-beam lithography. The current–voltage characteristics exhibit a rectifying behavior. The spectral sensitivity of the photodetector is recorded starting from 3 eV and extending far in the UV range. The maximal photoresponse is observed at a wavelength of 367 nm (sensitivity 1.9 mA/W). The response switching time of the photodetector is less than 0.1 s.

Study of the thermal conductivity of ZnO nanowires/PMMA composites

International Nuclear Information System (INIS)

Igamberdiev, Kh. T.; Yuldashev, Sh. U.; Cho, H. D.; Kang, T. W.; Rakhimova, Sh. M.; Akhmedov, T. Kh.

2012-01-01

From thermal conductivity measurements on ZnO nanowires (NWs)/poly(methyl methacrylate) PMMA composites, the thermal conductivities of the ZnO nanowires were determined. The thermal conductivity of a ZnO NW decreases considerably with decreasing nanowire diameter, and for a ZnO nanowire with a diameter of 250 nm, the thermal conductivity at room temperature is approximately two times lower than that of bulk ZnO at the same temperature. The results of this study show that the thermal conductivity of a ZnO NW is mainly determined by increased phonon-surface boundary scattering. These results could be useful for the design of ZnO-nanowire-based devices.

Nanowires and nanostructures fabrication using template methods

DEFF Research Database (Denmark)

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

2009-01-01

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

Laser Processed Silver Nanowire Network Transparent Electrodes for Novel Electronic Devices

Science.gov (United States)

Spechler, Joshua Allen

Silver nanowire network transparent conducting layers are poised to make headway into a space previously dominated by transparent conducting oxides due to the promise of a flexible, scaleable, lab-atmosphere processable alternative. However, there are many challenges standing in the way between research scale use and consumer technology scale adaptation of this technology. In this thesis we will explore many, and overcome a few of these challenges. We will address the poor conductivity at the narrow nanowire-nanowire junction points in the network by developing a laser based process to weld nanowires together on a microscopic scale. We address the need for a comparative metric for transparent conductors in general, by taking a device level rather than a component level view of these layers. We also address the mechanical, physical, and thermal limitations to the silver nanowire networks by making composites from materials including a colorless polyimide and titania sol-gel. Additionally, we verify our findings by integrating these processes into devices. Studying a hybrid organic/inorganic heterojunction photovoltaic device we show the benefits of a laser processed electrode. Green phosphorescent organic light emitting diodes fabricated on a solution phase processed silver nanowire based electrode show favorable device metrics compared to a conductive oxide electrode based control. The work in this thesis is intended to push the adoption of silver nanowire networks to further allow new device architectures, and thereby new device applications.

Nanowire size dependence on sensitivity of silicon nanowire field-effect transistor-based pH sensor

Science.gov (United States)

Lee, Ryoongbin; Kwon, Dae Woong; Kim, Sihyun; Kim, Sangwan; Mo, Hyun-Sun; Kim, Dae Hwan; Park, Byung-Gook

2017-12-01

In this study, we investigated the effects of nanowire size on the current sensitivity of silicon nanowire (SiNW) ion-sensitive field-effect transistors (ISFETs). The changes in on-current (I on) and resistance according to pH were measured in fabricated SiNW ISFETs of various lengths and widths. As a result, it was revealed that the sensitivity expressed as relative I on change improves as the width decreases. Through technology computer-aided design (TCAD) simulation analysis, the width dependence on the relative I on change can be explained by the observation that the target molecules located at the edge region along the channel width have a stronger effect on the sensitivity as the SiNW width is reduced. Additionally, the length dependence on the sensitivity can be understood in terms of the resistance ratio of the fixed parasitic resistance, including source/drain resistance, to the varying channel resistance as a function of channel length.

Poly(1-(2-carboxyethyl)pyrrole)/polypyrrole composite nanowires for glucose biosensor

International Nuclear Information System (INIS)

Jiang Hairong; Zhang Aifeng; Sun Yanan; Ru Xiaoning; Ge Dongtao; Shi Wei

2012-01-01

A novel glucose biosensor based on poly(1-(2-carboxyethyl)pyrrole) (PPyCOOH)/polypyrrole (PPy) composite nanowires was developed by immobilizing glucose oxidase (GOD) on the nanowires via covalent linkages. The PPyCOOH/PPy composite nanowires were fabricated by a facile two-step electrochemical synthesis route. First, PPy nanowires were synthesized in phosphate buffer solution using organic sulfonic acid, p-toluenesulfonate acid, as soft-template. Then, PPyCOOH/PPy composite nanowires were obtained by polymerizing 1-(2-carboxyethyl)pyrrole onto PPy nanowires via electrochemical method. Scanning electron microscopic, FT-IR spectra, X-ray photoelectron spectroscopy and cyclic voltammograms were used to characterize the structural and electrical behaviors of the composite nanowires. The PPyCOOH/PPy composite nanowires exhibited uniform diameter, high reactive site (-COOH), large specific surface, excellent electroactivity and good adhesion to electrode. The glucose biosensor was constructed by covalently coupling GOD to the composite nanowires. The biosensor response was rapid (5 s), highly sensitive (33.6 μA mM −1 cm −2 ) with a wide linear range (up to 10.0 mM) and low detection limit (0.63 μM); it also exhibited high stability and specificity to glucose. The attractive electrochemical and structural properties of PPyCOOH/PPy composite nanowires suggested potential application for electrocatalysis and biosensor.

Plasmonic engineering of metal-oxide nanowire heterojunctions in integrated nanowire rectification units

Energy Technology Data Exchange (ETDEWEB)

Lin, Luchan; Zhou, Y. Norman, E-mail: liulei@tsinghua.edu.cn, E-mail: nzhou@uwaterloo.ca [Department of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Zou, Guisheng; Liu, Lei, E-mail: liulei@tsinghua.edu.cn, E-mail: nzhou@uwaterloo.ca [Department of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Duley, Walt W. [Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

2016-05-16

We show that irradiation with femtosecond laser pulses can produce robust nanowire heterojunctions in coupled non-wetting metal-oxide Ag-TiO{sub 2} structures. Simulations indicate that joining arises from the effect of strong plasmonic localization in the region of the junction. Strong electric field effects occur in both Ag and TiO{sub 2} resulting in the modification of both surfaces and an increase in wettability of TiO{sub 2}, facilitating the interconnection of Ag and TiO{sub 2} nanowires. Irradiation leads to the creation of a thin layer of highly defected TiO{sub 2} in the contact region between the Ag and TiO{sub 2} nanowires. The presence of this layer allows the formation of a heterojunction and offers the possibility of engineering the electronic characteristics of interfacial structures. Rectifying junctions with single and bipolar properties have been generated in Ag-TiO{sub 2} nanowire circuits incorporating asymmetrical and symmetrical interfacial structures, respectively. This fabrication technique should be applicable for the interconnection of other heterogeneous metal-oxide nanowire components and demonstrates that femtosecond laser irradiation enables interfacial engineering for electronic applications of integrated nanowire structures.

Plasmonic engineering of metal-oxide nanowire heterojunctions in integrated nanowire rectification units

Science.gov (United States)

Lin, Luchan; Zou, Guisheng; Liu, Lei; Duley, Walt W.; Zhou, Y. Norman

2016-05-01

We show that irradiation with femtosecond laser pulses can produce robust nanowire heterojunctions in coupled non-wetting metal-oxide Ag-TiO2 structures. Simulations indicate that joining arises from the effect of strong plasmonic localization in the region of the junction. Strong electric field effects occur in both Ag and TiO2 resulting in the modification of both surfaces and an increase in wettability of TiO2, facilitating the interconnection of Ag and TiO2 nanowires. Irradiation leads to the creation of a thin layer of highly defected TiO2 in the contact region between the Ag and TiO2 nanowires. The presence of this layer allows the formation of a heterojunction and offers the possibility of engineering the electronic characteristics of interfacial structures. Rectifying junctions with single and bipolar properties have been generated in Ag-TiO2 nanowire circuits incorporating asymmetrical and symmetrical interfacial structures, respectively. This fabrication technique should be applicable for the interconnection of other heterogeneous metal-oxide nanowire components and demonstrates that femtosecond laser irradiation enables interfacial engineering for electronic applications of integrated nanowire structures.

Athermal avalanche in bilayer superconducting nanowire single-photon detectors

Energy Technology Data Exchange (ETDEWEB)

Verma, V. B., E-mail: verma@nist.gov; Lita, A. E.; Stevens, M. J.; Mirin, R. P.; Nam, S. W. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States)

2016-03-28

We demonstrate that two superconducting nanowires separated by a thin insulating barrier can undergo an avalanche process. In this process, Joule heating caused by a photodetection event in one nanowire and the associated production of athermal phonons which are transmitted through the barrier cause the transition of the adjacent nanowire from the superconducting to the normal state. We show that this process can be utilized in the fabrication of superconducting nanowire single photon detectors to improve the signal-to-noise ratio, reduce system jitter, maximize device area, and increase the external efficiency over a very broad range of wavelengths. Furthermore, the avalanche mechanism may provide a path towards a superconducting logic element based on athermal gating.

An innovative large scale integration of silicon nanowire-based field effect transistors

Science.gov (United States)

Legallais, M.; Nguyen, T. T. T.; Mouis, M.; Salem, B.; Robin, E.; Chenevier, P.; Ternon, C.

2018-05-01

Since the early 2000s, silicon nanowire field effect transistors are emerging as ultrasensitive biosensors while offering label-free, portable and rapid detection. Nevertheless, their large scale production remains an ongoing challenge due to time consuming, complex and costly technology. In order to bypass these issues, we report here on the first integration of silicon nanowire networks, called nanonet, into long channel field effect transistors using standard microelectronic process. A special attention is paid to the silicidation of the contacts which involved a large number of SiNWs. The electrical characteristics of these FETs constituted by randomly oriented silicon nanowires are also studied. Compatible integration on the back-end of CMOS readout and promising electrical performances open new opportunities for sensing applications.

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

Science.gov (United States)

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

2018-03-01

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

Broad spectral response photodetector based on individual tin-doped CdS nanowire

Directory of Open Access Journals (Sweden)

Weichang Zhou

2014-12-01

Full Text Available High purity and tin-doped 1D CdS micro/nano-structures were synthesized by a convenient thermal evaporation method. SEM, EDS, XRD and TEM were used to examine the morphology, composition, phase structure and crystallinity of as-prepared samples. Raman spectrum was used to confirm tin doped into CdS effectively. The effect of impurity on the photoresponse properties of photodetectors made from these as-prepared pure and tin-doped CdS micro/nano-structures under excitation of light with different wavelength was investigated. Various photoconductive parameters such as responsivity, external quantum efficiency, response time and stability were analyzed to evaluate the advantage of doped nanowires and the feasibility for photodetector application. Comparison with pure CdS nanobelt, the tin-doped CdS nanowires response to broader spectral range while keep the excellect photoconductive parameters. Both trapped state induced by tin impurity and optical whispering gallery mode microcavity effect in the doped CdS nanowires contribute to the broader spectral response. The micro-photoluminescence was used to confirm the whispering gallery mode effect and deep trapped state in the doped CdS nanowires.

Synthesis and characterization of single-crystalline zinc tin oxide nanowires

Science.gov (United States)

Shi, Jen-Bin; Wu, Po-Feng; Lin, Hsien-Sheng; Lin, Ya-Ting; Lee, Hsuan-Wei; Kao, Chia-Tze; Liao, Wei-Hsiang; Young, San-Lin

2014-05-01

Crystalline zinc tin oxide (ZTO; zinc oxide with heavy tin doping of 33 at.%) nanowires were first synthesized using the electrodeposition and heat treatment method based on an anodic aluminum oxide (AAO) membrane, which has an average diameter of about 60 nm. According to the field emission scanning electron microscopy (FE-SEM) results, the synthesized ZTO nanowires are highly ordered and have high wire packing densities. The length of ZTO nanowires is about 4 μm, and the aspect ratio is around 67. ZTO nanowires with a Zn/(Zn + Sn) atomic ratio of 0.67 (approximately 2/3) were observed from an energy dispersive spectrometer (EDS). X-ray diffraction (XRD) and corresponding selected area electron diffraction (SAED) patterns demonstrated that the ZTO nanowire is hexagonal single-crystalline. The study of ultraviolet/visible/near-infrared (UV/Vis/NIR) absorption showed that the ZTO nanowire is a wide-band semiconductor with a band gap energy of 3.7 eV.

As-Grown Gallium Nitride Nanowire Electromechanical Resonators

Science.gov (United States)

Montague, Joshua R.

Technological development in recent years has led to a ubiquity of micro- and nano-scale electromechanical devices. Sensors for monitoring temperature, pressure, mass, etc., are now found in nearly all electronic devices at both the industrial and consumer levels. As has been true for integrated circuit electronics, these electromechanical devices have continued to be scaled down in size. For many nanometer-scale structures with large surface-to-volume ratio, dissipation (energy loss) becomes prohibitively large causing a decreasing sensitivity with decreasing sensor size. In this work, gallium nitride (GaN) nanowires are investigated as singly-clamped (cantilever) mechanical resonators with typical mechanical quality factors, Q (equal to the ratio of resonance frequency to peak full-width-at-half-maximum-power) and resonance frequencies, respectively, at or above 30,000, and near 1 MHz. These Q values---in vacuum at room temperature---indicate very low levels of dissipation; they are essentially the same as those for bulk quartz crystal resonators that form the basis of simple clocks and mass sensors. The GaN nanowires have lengths and diameters, respectively, of approximately 15 micrometers and hundreds of nanometers. As-grown GaN nanowire Q values are larger than other similarly-sized, bottom-up, cantilever resonators and this property makes them very attractive for use as resonant sensors. We demonstrate the capability of detecting sub-monolayer levels of atomic layer deposited (ALD) films, and the robust nature of the GaN nanowires structure that allows for their 'reuse' after removal of such layers. In addition to electron microscope-based measurement techniques, we demonstrate the successful capacitive detection of a single nanowire using microwave homodyne reflectometry. This technique is then extended to allow for simultaneous measurements of large ensembles of GaN nanowires on a single sample, providing statistical information about the distribution of

Early stages of Cs adsorption mechanism for GaAs nanowire surface

Science.gov (United States)

Diao, Yu; Liu, Lei; Xia, Sihao; Feng, Shu

2018-03-01

In this study, the adsorption mechanism of Cs adatoms on the (100) surface of GaAs nanowire with [0001] growth direction is investigated utilizing first principles method based on density function theory. The adsorption energy, work function, atomic structure and electronic property of clean surface and Cs-covered surfaces with different coverage are discussed. Results show that when only one Cs is adsorbed on the surface, the most favorable adsorption site is BGa-As. With increasing Cs coverage, work function gradually decreases and gets its minimum at 0.75 ML, then rises slightly when Cs coverage comes to 1 ML, indicating the existence of 'Cs-kill' phenomenon. According to further analysis, Cs activation process can effectively reduce the work function due to the formation of a downward band bending region and surface dipole moment directing from Cs adatom to the surface. As Cs coverage increases, the conduction band minimum and valence band maximum both shift towards lower energy side, contributed by the orbital hybridization between Cs-5s, Cs-5p states and Ga-4p, As-4s, As-4p states near Fermi level. The theoretical calculations and analysis in this study can improve the Cs activation technology for negative electron affinity optoelectronic devices based on GaAs nanowires, and also provide a reference for the further Cs/O or Cs/NF3 activation process.

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.

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

OpenAIRE

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

2016-01-01

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

Strong sp-d exchange coupling in ZnMnTe/ZnMgTe core/shell nanowires

Energy Technology Data Exchange (ETDEWEB)

Wojnar, Piotr; Janik, Elzbieta; Szymura, Malgorzata; Zaleszczyk, Wojciech; Kret, Slawomir; Klopotowski, Lukasz; Wojciechowski, Tomasz; Baczewski, Lech T.; Wiater, Maciej; Karczewski, Grzegorz; Wojtowicz, Tomasz; Kossut, Jacek [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Suffczynski, Jan; Papierska, Joanna [Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw (Poland)

2014-07-15

In this work, our recent progress in the growth and optical studies of telluride nanowire heterostructures containing a small molar fraction of magnetic Mn-ions of only a few percent is overviewed. ZnMnTe/ZnMgTe core/shell nanowires (NWs) are grown by molecular beam epitaxy by employing the vapor-liquid-solid growth mechanism assisted with gold catalyst. The structures are studied by means of photoluminescence and microphotoluminescence in an external magnetic field. In the first step, however, an activation of the near band edge emission from ZnTe and ZnMnTe nanowires is described, which is achieved by coating the nanowires with shells made of ZnMgTe. The role of these shells is to passivate Zn(Mn)Te surface states. The incorporation of Mn ions into the crystalline lattice of ZnMnTe nanowires is manifested as a considerable blue shift of near band edge emission with increasing Mn concentration inside the nanowire cores, which reflects directly the increase of their energy gap. In an external magnetic field the near band edge emission exhibits a giant spectral redshift accompanied by an increase of the circular polarization of the emitted light. Both effect are fingerprints of giant Zeeman splitting of the band edges due to sp-d exchange interaction between the band carriers and magnetic Mn-ions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Nanowire FET Based Neural Element for Robotic Tactile Sensing Skin

Directory of Open Access Journals (Sweden)

William Taube Navaraj

2017-09-01

Full Text Available This paper presents novel Neural Nanowire Field Effect Transistors (υ-NWFETs based hardware-implementable neural network (HNN approach for tactile data processing in electronic skin (e-skin. The viability of Si nanowires (NWs as the active material for υ-NWFETs in HNN is explored through modeling and demonstrated by fabricating the first device. Using υ-NWFETs to realize HNNs is an interesting approach as by printing NWs on large area flexible substrates it will be possible to develop a bendable tactile skin with distributed neural elements (for local data processing, as in biological skin in the backplane. The modeling and simulation of υ-NWFET based devices show that the overlapping areas between individual gates and the floating gate determines the initial synaptic weights of the neural network - thus validating the working of υ-NWFETs as the building block for HNN. The simulation has been further extended to υ-NWFET based circuits and neuronal computation system and this has been validated by interfacing it with a transparent tactile skin prototype (comprising of 6 × 6 ITO based capacitive tactile sensors array integrated on the palm of a 3D printed robotic hand. In this regard, a tactile data coding system is presented to detect touch gesture and the direction of touch. Following these simulation studies, a four-gated υ-NWFET is fabricated with Pt/Ti metal stack for gates, source and drain, Ni floating gate, and Al2O3 high-k dielectric layer. The current-voltage characteristics of fabricated υ-NWFET devices confirm the dependence of turn-off voltages on the (synaptic weight of each gate. The presented υ-NWFET approach is promising for a neuro-robotic tactile sensory system with distributed computing as well as numerous futuristic applications such as prosthetics, and electroceuticals.

SYNTHESIS AND PHOTOLUMINESCENCE STUDIES ON ZINC OXIDE NANOWIRES

Directory of Open Access Journals (Sweden)

Nguyen Ngoc Long

2017-11-01

Full Text Available Semiconductor single crystal ZnO nanowires have been successfully synthesized by a simple method based on thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. The x-ray diffraction (XRD analysis shows that the ZnO nanowires are highly crystallized and have a typical wurtzite hexagonal structure with lattice constants a = 0.3246 nm and c = 0.5203 nm. The scanning electron microscopy (SEM images of nanowires indicate that diameters of the ZnO nanowires normally range from 100 to 300 nm and their lengths are several tens of micrometers. Photoluminescence (PL and photoluminescence excitation (PLE spectra of the nanowires were measured in the range of temperature from 15 K to the room temperature. Photoluminescence spectra at low temperatures exhibit a group of ultraviolet (UV narrow peaks in the region 368 nm ~ 390 nm, and a blue-green very broad peak at 500 nm. Origin of the emission lines in PL spectra and the lines in PLE spectra is discussed.

Staff perceptions of leadership during implementation of task-shifting in three surgical units.

Science.gov (United States)

Henderson, Amanda; Paterson, Karyn; Burmeister, Liz; Thomson, Bernadette; Young, Louise

2013-03-01

Registered nurses are difficult to recruit and retain. Task shifting, which involves reallocation of delegation, can reduce demand for registered nurses. Effective leadership is needed for successful task shifting. This study explored leadership styles of three surgical nurse unit managers. Staff completed surveys before and after the implementation of task shifting. Task shifting involved the introduction of endorsed enrolled nurses (licensed nurses who must practise under registered nurse supervision) to better utilize registered nurses. Implementation of task shifting occurred over 4 months in a 700-bed tertiary hospital, in southeast Queensland, Australia. A facilitator assisted nurse unit managers during implementation. The impact was assessed by comparison of data before (n = 49) and after (n = 72) task shifting from registered nurses and endorsed enrolled nurses (n = 121) who completed the Ward Organization Features Survey. Significant differences in leadership and staff organization subscales across the settings suggest that how change involving task shifting is implemented influences nurses' opinions of leadership. Leadership behaviours of nurse unit managers is a key consideration in managing change such as task shifting. Consistent and clear messages from leaders about practice change are viewed positively by nursing staff. In the short term, incremental change possibly results in staff maintaining confidence in leadership. © 2012 Blackwell Publishing Ltd.

Understanding the true shape of Au-catalyzed GaAs nanowires.

Science.gov (United States)

Jiang, Nian; Wong-Leung, Jennifer; Joyce, Hannah J; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati

2014-10-08

With increasing interest in nanowire-based devices, a thorough understanding of the nanowire shape is required to gain tight control of the quality of nanowire heterostructures and improve the performance of related devices. We present a systematic study of the sidewalls of Au-catalyzed GaAs nanowires by investigating the faceting process from the beginning with vapor-liquid-solid (VLS) nucleation, followed by the simultaneous radial growth on the sidewalls, and to the end with sidewall transformation during annealing. The VLS nucleation interface of our GaAs nanowires is revealed by examining cross sections of the nanowire, where the nanowire exhibits a Reuleaux triangular shape with three curved surfaces along {112}A. These curved surfaces are not thermodynamically stable and adopt {112}A facets during radial growth. We observe clear differences in radial growth rate between the ⟨112⟩A and ⟨112⟩B directions with {112}B facets forming due to the slower radial growth rate along ⟨112⟩B directions. These sidewalls transform to {110} facets after high temperature (>500 °C) annealing. A nucleation model is proposed to explain the origin of the Reuleaux triangular shape of the nanowires, and the sidewall evolution is explained by surface kinetic and thermodynamic limitations.

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

Science.gov (United States)

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

2017-08-01

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

Optical haze of randomly arranged silver nanowire transparent conductive films with wide range of nanowire diameters

Directory of Open Access Journals (Sweden)

M. Marus

2018-03-01

Full Text Available The effect of the diameter of randomly arranged silver nanowires on the optical haze of silver nanowire transparent conductive films was studied. Proposed simulation model behaved similarly with the experimental results, and was used to theoretically study the optical haze of silver nanowires with diameters in the broad range from 30 nm and above. Our results show that a thickening of silver nanowires from 30 to 100 nm results in the increase of the optical haze up to 8 times, while from 100 to 500 nm the optical haze increases only up to 1.38. Moreover, silver nanowires with diameter of 500 nm possess up to 5% lower optical haze and 5% higher transmittance than 100 nm thick silver nanowires for the same 10-100 Ohm/sq sheet resistance range. Further thickening of AgNWs can match the low haze of 30 nm thick AgNWs, but at higher transmittance. The results obtained from this work allow deeper analysis of the silver nanowire transparent conductive films from the perspective of the diameter of nanowires for various optoelectronic devices.

Silicon nanowire networks for multi-stage thermoelectric modules

International Nuclear Information System (INIS)

Norris, Kate J.; Garrett, Matthew P.; Zhang, Junce; Coleman, Elane; Tompa, Gary S.; Kobayashi, Nobuhiko P.

2015-01-01

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

Formation of crystalline InGaO_3(ZnO)_n nanowires via the solid-phase diffusion process using a solution-based precursor

International Nuclear Information System (INIS)

Guo, Yujie; Seo, Jin Won; Bilzen, Bart Van; Locquet, Jean Pierre

2015-01-01

One-dimensional single crystalline InGaO_3(ZnO)_n (IGZO) nanostructures have great potential for various electrical and optical applications. This paper demonstrates for the first time, to our knowledge, a non-vacuum route for the synthesis of IGZO nanowires by annealing ZnO nanowires covered with solution-based IGZO precursor. This method results in nanowires with highly periodic IGZO superlattice structure. The phase transition of IGZO precursor during thermal treatment was systematically studied. Transmission electron microscopy studies reveal that the formation of the IGZO structure is driven by anisotropic inter-diffusion of In, Ga, and Zn atoms, and also by the crystallization of the IGZO precursor. Optical measurements using cathodoluminescence and UV-vis spectroscopy confirm that the nanowires consist of the IGZO compound with wide optical band gap and suppressed luminescence. (paper)

Composition–dependent growth dynamics of selectively grown InGaAs nanowires

International Nuclear Information System (INIS)

Kohashi, Y; Hara, S; Motohisa, J

2014-01-01

We grew gallium-rich (x > 0.50) and indium-rich (x < 0.50) In 1 − x Ga x As nanowires by catalyst–free selective-area metal–organic vapor-phase epitaxy (SA-MOVPE), and compared their growth dynamics dependence on V/III ratio. It was found that the growth dynamics of In 1 − x Ga x As nanowires is clearly dependent on the alloy composition x. Specifically, for gallium–rich nanowire growth, the axial growth rate of nanowires initially increased with decreasing V/III ratio, and then started to decrease when the V/III ratio continued to decrease below a critical value. On the other hand, axial growth rate of indium-rich nanowires monotonically decreased with decreasing V/III ratio. In addition, the alloy composition was strongly dependent on the V/III ratio for gallium-rich nanowire growth, while it was relatively independent of the V/III ratio for indium-rich nanowire growth. We discuss the origin of dissimilarity in the growth dynamics dependence on V/III ratio between gallium-rich and indium-rich InGaAs nanowire growth, and conclude that it is due to the inherent dissimilarity between GaAs and InAs. Our finding provides important guidelines for achieving precise control of the diameter, height, and alloy composition of nanowires suitable for future nanowire-based electronics. (papers)

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

International Nuclear Information System (INIS)

Shariati, Mohsen

2017-01-01

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

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...

Diameter-dependent coloration of silver nanowires

International Nuclear Information System (INIS)

Stewart, Mindy S; Qiu Chao; Jiang Chaoyang; Kattumenu, Ramesh; Singamaneni, Srikanth

2011-01-01

Silver nanowires were synthesized with a green method and characterized with microscopic and diffractometric methods. The correlation between the colors of the nanowires deposited on a solid substrate and their diameters was explored. Silver nanowires that appear similar in color in the optical micrographs have very similar diameters as determined by atomic force microscopy. We have summarized the diameter-dependent coloration for these silver nanowires. An optical interference model was applied to explain such correlation. In addition, microreflectance spectra were obtained from individual nanowires and the observed spectra can be explained with the optical interference theory. This work provides a cheap, quick and simple screening method for studying the diameter distribution of silver nanowires, as well as the diameter variations of individual silver nanowires, without complicated sample preparation.

Synthesis of platinum nanowire networks using a soft template.

Science.gov (United States)

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

2007-12-01

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

Multiple simultaneous fabrication of molecular nanowires using nanoscale electrocrystallization

International Nuclear Information System (INIS)

Hasegawa, Hiroyuki; Ueda, Rieko; Kubota, Tohru; Mashiko, Shinro

2006-01-01

We carried out a multiple simultaneous fabrication based on the nanoscale electrocrystallization to simultaneously construct molecular nanowires at two or more positions. This substrate-independent nanoscale electrocrystallization process enables nanowires fabrication at specific positions using AC. We also succeeded in multiple fabrications only at each gap between the electrode tips. We found that π-stack was formed along the long axis of the nanowires obtained by analyzing the selected-area electron diffraction. We believe this technique has the potential for expansion to the novel low-cost and energy-saving fabrication of high-performance nanodevices

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.

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

Science.gov (United States)

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

2014-05-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-05-01

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

Enhanced Electron Mobility in Nonplanar Tensile Strained Si Epitaxially Grown on SixGe1-x Nanowires.

Science.gov (United States)

Wen, Feng; Tutuc, Emanuel

2018-01-10

We report the growth and characterization of epitaxial, coherently strained Si x Ge 1-x -Si core-shell nanowire heterostructure through vapor-liquid-solid growth mechanism for the Si x Ge 1-x core, followed by an in situ ultrahigh-vacuum chemical vapor deposition for the Si shell. Raman spectra acquired from individual nanowire reveal the Si-Si, Si-Ge, and Ge-Ge modes of the Si x Ge 1-x core and the Si-Si mode of the shell. Because of the compressive (tensile) strain induced by lattice mismatch, the core (shell) Raman modes are blue (red) shifted compared to those of unstrained bare Si x Ge 1-x (Si) nanowires, in good agreement with values calculated using continuum elasticity model coupled with lattice dynamic theory. A large tensile strain of up to 2.3% is achieved in the Si shell, which is expected to provide quantum confinement for electrons due to a positive core-to-shell conduction band offset. We demonstrate n-type metal-oxide-semiconductor field-effect transistors using Si x Ge 1-x -Si core-shell nanowires as channel and observe a 40% enhancement of the average electron mobility compared to control devices using Si nanowires due to an increased electron mobility in the tensile-strained Si shell.

Strong diameter-dependence of nanowire emission coupled to waveguide modes

Energy Technology Data Exchange (ETDEWEB)

Dam, Dick van, E-mail: a.d.v.dam@tue.nl; Haverkort, Jos E. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Abujetas, Diego R.; Sánchez-Gil, José A. [Instituto de Estructura de la Materia (IEM-CSIC), Consejo Superior de Investigaciones Científicas Serrano, 121, 28006 Madrid (Spain); Bakkers, Erik P. A. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Gómez Rivas, Jaime, E-mail: j.gomezrivas@differ.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Dutch Institute for Fundamental Energy Research DIFFER, P.O. Box 6336, 5600 HH Eindhoven (Netherlands)

2016-03-21

The emission from nanowires can couple to waveguide modes supported by the nanowire geometry, thus governing the far-field angular pattern. To investigate the geometry-induced coupling of the emission to waveguide modes, we acquire Fourier microscopy images of the photoluminescence of nanowires with diameters ranging from 143 to 208 nm. From the investigated diameter range, we conclude that a few nanometers difference in diameter can abruptly change the coupling of the emission to a specific mode. Moreover, we observe a diameter-dependent width of the Gaussian-shaped angular pattern in the far-field emission. This dependence is understood in terms of interference of the guided modes, which emit at the end facets of the nanowire. Our results are important for the design of quantum emitters, solid state lighting, and photovoltaic devices based on nanowires.

Controlled assembly of multi-segment nanowires by histidine-tagged peptides

Energy Technology Data Exchange (ETDEWEB)

Wang, Aijun A; Lee, Joun; Jenikova, Gabriela; Mulchandani, Ashok; Myung, Nosang V; Chen, Wilfred [Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521 (United States)

2006-07-28

A facile technique was demonstrated for the controlled assembly and alignment of multi-segment nanowires using bioengineered polypeptides. An elastin-like-polypeptide (ELP)-based biopolymer consisting of a hexahistine cluster at each end (His{sub 6}-ELP-His{sub 6}) was generated and purified by taking advantage of the reversible phase transition property of ELP. The affinity between the His{sub 6} domain of biopolymers and the nickel segment of multi-segment nickel/gold/nickel nanowires was exploited for the directed assembly of nanowires onto peptide-functionalized electrode surfaces. The presence of the ferromagnetic nickel segments on the nanowires allowed the control of directionality by an external magnetic field. Using this method, the directed assembly and positioning of multi-segment nanowires across two microfabricated nickel electrodes in a controlled manner was accomplished with the expected ohmic contact.

Methods for synthesizing metal oxide nanowires

Science.gov (United States)

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

2016-08-09

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

Towards quantum dots on GaAs nanowires

Energy Technology Data Exchange (ETDEWEB)

Moesl, Johannes; Ludwig, Stefan [Fakultaet fuer Physik, Center for NanoScience, LMU Munich, Geschwister-Scholl- Platz 1, D-80539 Muenchen (Germany); Fontcuberta i Morral, Anna [TU Munich, Walter Schottky Institut, Am Coulombwall 3, 85748 Garching (Germany); EPF, Lausanne (Switzerland)

2009-07-01

Semiconductor nanowires is an emergent research topic in the field of nanoelectronics, as they form an excellent building block for 0D and 1D applications and allow novel architectures and material combinations. We study electronic transport properties of catalyst-free MBE grown GaAs nanowires, p-doped at a number of different doping levels. Detailed characterization of the wires including electronic contacts fabricated by e-beam lithography and based on palladium or annealed zinc-silver alloys are discussed. Contact properties and a pronounced hysteresis of the current through the nanowires, as a backgate-voltage is swept, are explained within tentative models. In addition we present first transport measurements on quantum dots, which are defined electrostatically as well as by etched constrictions.

Timoshenko beam model for buckling of piezoelectric nanowires with surface effects

Science.gov (United States)

2012-01-01

This paper investigates the buckling behavior of piezoelectric nanowires under distributed transverse loading, within the framework of the Timoshenko beam theory, and in the presence of surface effects. Analytical relations are given for the critical force of axial buckling of nanowires by accounting for the effects of surface elasticity, residual surface tension, and transverse shear deformation. Through an example, it is shown that the critical electric potential of buckling depends on both the surface stresses and piezoelectricity. This study may be helpful in the characterization of the mechanical properties of nanowires and in the calibration of the nanowire-based force sensors. PMID:22453063

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

Science.gov (United States)

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

2018-02-23

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

Improved Long-Term Stability of Transparent Conducting Electrodes Based on Double-Laminated Electrosprayed Antimony Tin Oxides and Ag Nanowires

Directory of Open Access Journals (Sweden)

Koo B.-R.

2017-06-01

Full Text Available We fabricated double-laminated antimony tin oxide/Ag nanowire electrodes by spin-coating and electrospraying. Compared to pure Ag nanowire electrodes and single-laminated antimony tin oxide/Ag nanowire electrodes, the double-laminated antimony tin oxide/Ag nanowire electrodes had superior transparent conducting electrode performances with sheet resistance ~19.8 Ω/□ and optical transmittance ~81.9%; this was due to uniform distribution of the connected Ag nanowires because of double lamination of the metallic Ag nanowires without Ag aggregation despite subsequent microwave heating at 250°C. They also exhibited excellent and superior long-term chemical and thermal stabilities and adhesion to substrate because double-laminated antimony tin oxide thin films act as the protective layers between Ag nanowires, blocking Ag atoms penetration.

Tunable absorption resonances in the ultraviolet for InP nanowire arrays.

Science.gov (United States)

Aghaeipour, Mahtab; Anttu, Nicklas; Nylund, Gustav; Samuelson, Lars; Lehmann, Sebastian; Pistol, Mats-Erik

2014-11-17

The ability to tune the photon absorptance spectrum is an attracting way of tailoring the response of devices like photodetectors and solar cells. Here, we measure the reflectance spectra of InP substrates patterned with arrays of vertically standing InP nanowires. Using the reflectance spectra, we calculate and analyze the corresponding absorptance spectra of the nanowires. We show that we can tune absorption resonances for the nanowire arrays into the ultraviolet by decreasing the diameter of the nanowires. When we compare our measurements with electromagnetic modeling, we generally find good agreement. Interestingly, the remaining differences between modeled and measured spectra are attributed to a crystal-phase dependence in the refractive index of InP. Specifically, we find indication of significant differences in the refractive index between the modeled zinc-blende InP nanowires and the measured wurtzite InP nanowires in the ultraviolet. We believe that such crystal-phase dependent differences in the refractive index affect the possibility to excite optical resonances in the large wavelength range of 345 InP nanowire-based solar cells and photodetectors.

Quantitative measurements of C-reactive protein using silicon nanowire arrays

Directory of Open Access Journals (Sweden)

Min-Ho Lee

2008-03-01

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

Localized temperature and chemical reaction control in nanoscale space by nanowire array.

Science.gov (United States)

Jin, C Yan; Li, Zhiyong; Williams, R Stanley; Lee, K-Cheol; Park, Inkyu

2011-11-09

We introduce a novel method for chemical reaction control with nanoscale spatial resolution based on localized heating by using a well-aligned nanowire array. Numerical and experimental analysis shows that each individual nanowire could be selectively and rapidly Joule heated for local and ultrafast temperature modulation in nanoscale space (e.g., maximum temperature gradient 2.2 K/nm at the nanowire edge; heating/cooling time chemical reactions such as polymer decomposition/cross-linking and direct and localized hydrothermal synthesis of metal oxide nanowires were demonstrated.

Fully Digital Chaotic Differential Equation-based Systems And Methods

KAUST Repository

Radwan, Ahmed Gomaa Ahmed; Zidan, Mohammed A.; Salama, Khaled N.

2012-01-01

Various embodiments are provided for fully digital chaotic differential equation-based systems and methods. In one embodiment, among others, a digital circuit includes digital state registers and one or more digital logic modules configured to obtain a first value from two or more of the digital state registers; determine a second value based upon the obtained first values and a chaotic differential equation; and provide the second value to set a state of one of the plurality of digital state registers. In another embodiment, a digital circuit includes digital state registers, digital logic modules configured to obtain outputs from a subset of the digital shift registers and to provide the input based upon a chaotic differential equation for setting a state of at least one of the subset of digital shift registers, and a digital clock configured to provide a clock signal for operating the digital shift registers.

Fully Digital Chaotic Differential Equation-based Systems And Methods

KAUST Repository

Radwan, Ahmed Gomaa Ahmed

2012-09-06

Various embodiments are provided for fully digital chaotic differential equation-based systems and methods. In one embodiment, among others, a digital circuit includes digital state registers and one or more digital logic modules configured to obtain a first value from two or more of the digital state registers; determine a second value based upon the obtained first values and a chaotic differential equation; and provide the second value to set a state of one of the plurality of digital state registers. In another embodiment, a digital circuit includes digital state registers, digital logic modules configured to obtain outputs from a subset of the digital shift registers and to provide the input based upon a chaotic differential equation for setting a state of at least one of the subset of digital shift registers, and a digital clock configured to provide a clock signal for operating the digital shift registers.

Electron Transport Properties of Ge nanowires

Science.gov (United States)

Hanrath, Tobias; Khondaker, Saiful I.; Yao, Zhen; Korgel, Brian A.

2003-03-01

Electron Transport Properties of Ge nanowires Tobias Hanrath*, Saiful I. Khondaker, Zhen Yao, Brian A. Korgel* *Dept. of Chemical Engineering, Dept. of Physics, Texas Materials Institute, and Center for Nano- and Molecular Science and Technology University of Texas at Austin, Austin, Texas 78712-1062 e-mail: korgel@mail.che.utexas.edu Germanium (Ge) nanowires with diameters ranging from 6 to 50 nm and several micrometer in length were grown via a supercritical fluid-liquid-solid synthesis. Parallel electron energy loss spectroscopy (PEELS) was employed to study the band structure and electron density in the Ge nanowires. The observed increase in plasmon peak energy and peak width with decreasing nanowire diameter is attributed to quantum confinement effects. For electrical characterization, Ge nanowires were deposited onto a patterned Si/SiO2 substrate. E-beam lithography was then used to form electrode contacts to individual nanowires. The influence of nanowire diameter, surface chemistry and crystallographic defects on electron transport properties were investigated and the comparison of Ge nanowire conductivity with respect to bulk, intrinsic Ge will be presented.

Polarity Control of Heteroepitaxial GaN Nanowires on Diamond.

Science.gov (United States)

Hetzl, Martin; Kraut, Max; Hoffmann, Theresa; Stutzmann, Martin

2017-06-14

Group III-nitride materials such as GaN nanowires are characterized by a spontaneous polarization within the crystal. The sign of the resulting sheet charge at the top and bottom facet of a GaN nanowire is determined by the orientation of the wurtzite bilayer of the different atomic species, called N and Ga polarity. We investigate the polarity distribution of heteroepitaxial GaN nanowires on different substrates and demonstrate polarity control of GaN nanowires on diamond. Kelvin Probe Force Microscopy is used to determine the polarity of individual selective area-grown and self-assembled nanowires over a large scale. At standard growth conditions, mixed polarity occurs for selective GaN nanowires on various substrates, namely on silicon, on sapphire and on diamond. To obtain control over the growth orientation on diamond, the substrate surface is modified by nitrogen and oxygen plasma exposure prior to growth, and the growth parameters are adjusted simultaneously. We find that the surface chemistry and the substrate temperature are the decisive factors for obtaining control of up to 93% for both polarity types, whereas the growth mode, namely selective area or self-assembled growth, does not influence the polarity distribution significantly. The experimental results are discussed by a model based on the interfacial bonds between the GaN nanowires, the termination layer, and the substrate.

Single n+-i-n+ InP nanowires for highly sensitive terahertz detection.

Science.gov (United States)

Peng, Kun; Parkinson, Patrick; Gao, Qian; Boland, Jessica L; Li, Ziyuan; Wang, Fan; Mokkapati, Sudha; Fu, Lan; Johnston, Michael B; Tan, Hark Hoe; Jagadish, Chennupati

2017-03-24

Developing single-nanowire terahertz (THz) electronics and employing them as sub-wavelength components for highly-integrated THz time-domain spectroscopy (THz-TDS) applications is a promising approach to achieve future low-cost, highly integrable and high-resolution THz tools, which are desirable in many areas spanning from security, industry, environmental monitoring and medical diagnostics to fundamental science. In this work, we present the design and growth of n + -i-n + InP nanowires. The axial doping profile of the n + -i-n + InP nanowires has been calibrated and characterized using combined optical and electrical approaches to achieve nanowire devices with low contact resistances, on which the highly-sensitive InP single-nanowire photoconductive THz detectors have been demonstrated. While the n + -i-n + InP nanowire detector has a only pA-level response current, it has a 2.5 times improved signal-to-noise ratio compared with the undoped InP nanowire detector and is comparable to traditional bulk THz detectors. This performance indicates a promising path to nanowire-based THz electronics for future commercial applications.

Corrosion behavior of Haynes registered 230 registered nickel-based super-alloys for integrated coal gasification combined cycle syngas plants. A plant exposure study

International Nuclear Information System (INIS)

Lee, Sungkyu; Lee, Jieun; Kang, Suk-Hwan; Lee, Seung-Jong; Yun, Yongseung; Kim, Min Jung

2015-01-01

The corrosion behavior of commercially available Haynes registered 230 registered nickel-based alloy samples was investigated by exposure to coal-gasifying integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160-300 C). The morphological and microstructural analyses of the exposed samples were conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis on the external surface of the recovered corrosion test samples to obtain information of the corrosion scale. These analyses based on the pre- and post-exposure corrosion test samples combined with thermodynamic Ellingham-Pourbaix stability diagrams provided preliminary insight into the mechanism of the observed corrosion behavior prevailing in the piping materials that connected the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material wastage was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested: the observed material waste and corrosion behavior of the Haynes registered 230 registered nickel-based alloy samples cut off from the coal syngas integrated coal gasification combined cycle plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered. This contribution continues the already published studies of the Fe-Ni-Cr-Co alloy Haynes registered 556 registered .

Effect of advanced nanowire-based targets in nanosecond laser-matter interaction (invited)

Energy Technology Data Exchange (ETDEWEB)

Lanzalone, G., E-mail: Gaetano.Lanzalone@ct.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore,” Via delle Olimpiadi, 94100 Enna (Italy); Altana, C. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Mascali, D.; Tudisco, S. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Muoio, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Malferrari, L.; Odorici, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Viale B. Pichat 6/2, 40127 Bologna (Italy); Malandrino, G. [Dipartimento di Scienze Chimiche and INSTM UdR, Università degli Studi di Catania, Catania (Italy)

2016-02-15

An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ag nanowires on laser energy absorption in the ns time domain has been carried out at the Laser Energy for Nuclear Science laboratory of INFN-LNS in Catania. The tested targets were realized at INFN-Bologna by anodizing aluminium sheets in order to obtain layers of porous Al{sub 2}O{sub 3} of different thicknesses, on which nanowires of various metals are grown by electro-deposition with different heights. Targets were then irradiated by using a Nd:YAG laser at different pumping energies. Advanced diagnostic tools were used for characterizing the plasma plume and ion production. As compared with targets of pure Al, a huge enhancement (of almost two order of magnitude) of the X-ray flux emitted by the plasma has been observed when using the nanostructured targets, with a corresponding decrease of the “optical range” signal, pointing out that the energetic content of the laser produced plasma was remarkably increased. This analysis was furthermore confirmed from time-of-flight spectra.

Effect of advanced nanowire-based targets in nanosecond laser-matter interaction (invited)

Science.gov (United States)

Lanzalone, G.; Altana, C.; Mascali, D.; Muoio, A.; Malferrari, L.; Odorici, F.; Malandrino, G.; Tudisco, S.

2016-02-01

An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ag nanowires on laser energy absorption in the ns time domain has been carried out at the Laser Energy for Nuclear Science laboratory of INFN-LNS in Catania. The tested targets were realized at INFN-Bologna by anodizing aluminium sheets in order to obtain layers of porous Al2O3 of different thicknesses, on which nanowires of various metals are grown by electro-deposition with different heights. Targets were then irradiated by using a Nd:YAG laser at different pumping energies. Advanced diagnostic tools were used for characterizing the plasma plume and ion production. As compared with targets of pure Al, a huge enhancement (of almost two order of magnitude) of the X-ray flux emitted by the plasma has been observed when using the nanostructured targets, with a corresponding decrease of the "optical range" signal, pointing out that the energetic content of the laser produced plasma was remarkably increased. This analysis was furthermore confirmed from time-of-flight spectra.

Hybrid heterojunction solar cell based on organic-inorganic silicon nanowire array architecture.

Science.gov (United States)

Shen, Xiaojuan; Sun, Baoquan; Liu, Dong; Lee, Shuit-Tong

2011-12-07

Silicon nanowire arrays (SiNWs) on a planar silicon wafer can be fabricated by a simple metal-assisted wet chemical etching method. They can offer an excellent light harvesting capability through light scattering and trapping. In this work, we demonstrated that the organic-inorganic solar cell based on hybrid composites of conjugated molecules and SiNWs on a planar substrate yielded an excellent power conversion efficiency (PCE) of 9.70%. The high efficiency was ascribed to two aspects: one was the improvement of the light absorption by SiNWs structure on the planar components; the other was the enhancement of charge extraction efficiency, resulting from the novel top contact by forming a thin organic layer shell around the individual silicon nanowire. On the contrary, the sole planar junction solar cell only exhibited a PCE of 6.01%, due to the lower light trapping capability and the less hole extraction efficiency. It indicated that both the SiNWs structure and the thin organic layer top contact were critical to achieve a high performance organic/silicon solar cell. © 2011 American Chemical Society

Flexible ultraviolet photodetectors based on ZnO-SnO2 heterojunction nanowire arrays

Science.gov (United States)

Lou, Zheng; Yang, Xiaoli; Chen, Haoran; Liang, Zhongzhu

2018-02-01

A ZnO-SnO2 nanowires (NWs) array, as a metal oxide semiconductor, was successfully synthesized by a near-field electrospinning method for the applications as high performance ultraviolet photodetectors. Ultraviolet photodetectors based on a single nanowire exhibited excellent photoresponse properties to 300 nm ultraviolet light illumination including ultrahigh I on/I off ratios (up to 103), good stability and reproducibility because of the separation between photo-generated electron-hole pairs. Moreover, the NWs array shows an enhanced photosensing performance. Flexible photodetectors on the PI substrates with similar tendency properties were also fabricated. In addition, under various bending curvatures and cycles, the as-fabricated flexible photodetectors revealed mechanical flexibility and good stable electrical properties, showing that they have the potential for applications in future flexible photoelectron devices. Project supported by the National Science Foundation of China (No. 61504136) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine and Physics, Chinese Academy of Sciences.

Two-dimensional nanowires on homoepitaxial interfaces: Atomic-scale mechanism of breakdown and disintegration

Science.gov (United States)

Michailov, Michail; Ranguelov, Bogdan

2018-03-01

We present a model for hole-mediated spontaneous breakdown of ahomoepitaxial two-dimensional (2D) flat nanowire based exclusively on random, thermally-activated motion of atoms. The model suggests a consecutive three-step mechanism driving the rupture and complete disintegration of the nanowire on a crystalline surface. The breakdown scenario includes: (i) local narrowing of a part of the stripe to a monatomic chain, (ii) formation of a recoverable single vacancy or a 2D vacancy cluster that causes temporary nanowire rupture, (iii) formation of a non-recoverable 2D hole leading to permanent nanowire breakdown. These successive events in the temporal evolution of the nanowire morphology bring the nanowire stripe into an irreversible unstable state, leading to a dramatic change in its peculiar physical properties and conductivity. The atomistic simulations also reveal a strong increase of the nanowire lifetime with an enlargement of its width and open up a way for a fine atomic-scale control of the nanowire lifetime and structural, morphological and thermodynamic stability.

Conducting polymer nanowire arrays for high performance supercapacitors.

Science.gov (United States)

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

2014-01-15

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

Single Nanowire Probe for Single Cell Endoscopy and Sensing

Science.gov (United States)

Yan, Ruoxue

The ability to manipulate light in subwavelength photonic and plasmonic structures has shown great potentials in revolutionizing how information is generated, transformed and processed. Chemically synthesized nanowires, in particular, offers a unique toolbox not only for highly compact and integrated photonic modules and devices, including coherent and incoherent light sources, waveguides, photodetectors and photovoltaics, but also for new types of nanoscopic bio-probes for spot cargo delivery and in-situ single cell endoscopy and sensing. Such nanowire probes would enable us to carry out intracellular imaging and probing with high spatial resolution, monitor in-vivo biological processes within single living cells and greatly improve our fundamental understanding of cell functions, intracellular physiological processes, and cellular signal pathways. My work is aimed at developing a material and instrumental platform for such single nanowire probe. Successful optical integration of Ag nanowire plasmonic waveguides, which offers deep subwavelength mode confinement, and conventional photonic waveguides was demonstrated on a single nanowire level. The highest plasmonic-photonic coupling efficiency coupling was found at small coupling angles and low input frequencies. The frequency dependent propagation loss was observed in Ag nanowire and was confirmed by quantitative measurement and in agreement with theoretical expectations. Rational integration of dielectric and Ag nanowire waveguide components into hybrid optical-plasmonic routing devices has been demonstrated. This capability is essential for incorporating sub-100nm Ag nanowire waveguides into optical fiber based nanoprobes for single cell endoscopy. The nanoprobe system based on single nanowire waveguides was demonstrated by optically coupling semiconductor or metal nanowire with an optical fiber with tapered tip. This nanoprobe design requires minimal instrumentation which makes it cost efficient and readily

Study of optical absorbance in porous silicon nanowires for photovoltaic applications

KAUST Repository

Charrier, Joë l; Najar, Adel; Pirasteh, Parastesh

2013-01-01

Porous silicon nanowires (PSiNWs) layers fabrication was reported. Reflectance spectra were measured as a function of the nanowire length and were inferior to 0.1% and a strong photoluminescence (PL) signal was measured from samples. Models based

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.

Extinction properties of metallic nanowires: Quantum diffraction and retardation effects

Energy Technology Data Exchange (ETDEWEB)

Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of); Department of Nano Sciences, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

2015-10-09

The standard Mie theory for the extinction of electromagnetic radiation by a metal cylinder that is irradiated by a normally incident plane wave is extended to the case of a metallic nanowire, where two quantum longitudinal waves are excited. The modification of the Mie theory due to quantum diffraction effects is included by employing the quantum hydrodynamic approximation and applying the appropriate quantum additional boundary conditions. The extinction properties of the system and their differences with previous treatments based on the standard local and nonlocal models are shown. Also, as an example the validity of the nonretarded approximation in the quantum nonlocal optical response of a sodium nanowire is discussed. - Highlights: • Extinction properties of metallic nanowires in the presence of quantum diffraction and retardation effects are studied. • The differences of new results with previous findings based on the standard local and nonlocal models are shown. • The validity of the nonretarded approximation in the quantum nonlocal optical response of a sodium nanowire is discussed.

Chip-to-chip SnO2 nanowire network sensors for room temperature H2 detection

Science.gov (United States)

Köck, A.; Brunet, E.; Mutinati, G. C.; Maier, T.; Steinhauer, S.

2012-06-01

The employment of nanowires is a very powerful strategy to improve gas sensor performance. We demonstrate a gas sensor device, which is based on silicon chip-to-chip synthesis of ultralong tin oxide (SnO2) nanowires. The sensor device employs an interconnected SnO2 nanowire network configuration, which exhibits a huge surface-to-volume ratio and provides full access of the target gas to the nanowires. The chip-to-chip SnO2 nanowire device is able to detect a H2 concentration of only 20 ppm in synthetic air with ~ 60% relative humidity at room temperature. At an operating temperature of 300°C a concentration of 50 ppm H2 results in a sensitivity of 5%. At this elevated temperature the sensor shows a linear response in a concentration range between 10 ppm and 100 ppm H2. The SnO2-nanowire fabrication procedure based on spray pyrolysis and subsequent annealing is performed at atmospheric pressure, requires no vacuum and allows upscale of the substrate to a wafer size. 3D-integration with CMOS chips is proposed as viable way for practical realization of smart nanowire based gas sensor devices for the consumer market.

Wurtzite InP nanowire arrays grown by selective area MOCVD

International Nuclear Information System (INIS)

Chu, Hyung-Joon; Stewart, Lawrence; Yeh, Ting-Wei; Dapkus, P.D.

2010-01-01

InP nanowires are a unique material phase because this normally zincblende material forms in the wurtzite crystal structure below a critical diameter owing to the contribution of sidewalls to the total formation energy. This may allow control of the carrier transport and optical properties of InP nanowires for applications such as nano scale transistors, lasers and detectors. In this work, we describe the fabrication of InP nanowire arrays by selective area growth using MOCVD in the diameter range where the wurtzite structure is formed. The spatial growth rate in selective area growth is modeled by a diffusion model for the precursors. The proposed model achieves an average error of 9%. Electron microscopy shows that the grown InP nanowires are in the wurtzite crystal phase with many stacking faults. The threshold diameter of the crystal phase transition of InP nanowires is larger than the thermodynamic estimation. In order to explain this tendency, we propose a surface kinetics model based on a 2 x 2 reconstruction. This model can explain the increased tendency for wurtzite nanowire formation on InP (111)A substrates and the preferred growth direction of binary III-V compound semiconductor nanowires. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Optical and field emission properties of layer-structure GaN nanowires

Energy Technology Data Exchange (ETDEWEB)

Cui, Zhen [Science School, Xi’an University of Technology, Xi’an 710048 (China); School of automation and Information Engineering, Xi’an University of Technology, Xi’an 710048 (China); Li, Enling, E-mail: Lienling@xaut.edu.cn [Science School, Xi’an University of Technology, Xi’an 710048 (China); Shi, Wei; Ma, Deming [Science School, Xi’an University of Technology, Xi’an 710048 (China)

2014-08-15

Highlights: • The layer-structure GaN nanowires with hexagonal-shaped cross-sections are produced via a process based on the CVD method. • The diameter of the layer-structure GaN nanowire gradually decreases from ∼500 nm to ∼200 nm along the wire axis. • The layer-structure GaN nanowire film possesses good field emission property. - Abstract: A layer-structure gallium nitride (GaN) nanowires, grown on Pt-coated n-type Si (1 1 1) substrate, have been synthesized using chemical vapor deposition (CVD). The results show: (1) SEM indicates that the geometry structure is layer-structure. HRTEM indicates that GaN nanowire’s preferential growth direction is along [0 0 1] direction. (2) The room temperature PL emission spectrum of the layer-structure GaN nanowires has a peak at 375 nm, which proves that GaN nanowires have potential application in light-emitting nano-devices. (3) Field-emission measurements show that the layer-structure GaN nanowires film has a low turn-on field of 4.39 V/μm (at room temperature), which is sufficient for electron emission devices, field emission displays and vacuum nano-electronic devices. The growth mechanism for GaN nanowires has also been discussed briefly.

Semiconductor nanowires and templates for electronic applications

Energy Technology Data Exchange (ETDEWEB)

Ying, Xiang

2009-07-15

This thesis starts by developing a platform for the organized growth of nanowires directly on a planar substrate. For this, a method to fabricate horizontal porous alumina membranes is studied. The second part of the thesis focuses on the study of nanowires. It starts by the understanding of the growth mechanisms of germanium nanowires and follows by the structural and electrical properties at the single nanowire level. Horizontally aligned porous anodic alumina (PAA) was used as a template for the nanowire synthesis. Three PAA arrangements were studied: - high density membranes - micron-sized fingers - multi-contacts Membranes formed by a high density of nanopores were obtained by anodizing aluminum thin films. Metallic and semiconducting nanowires were synthesized into the PAA structures via DC deposition, pulsed electro-depostion and CVD growth. The presence of gold, copper, indium, nickel, tellurium, and silicon nanowires inside PAA templates was verified by SEM and EDX analysis. Further, room-temperature transport measurements showed that the pores are completely filled till the bottom of the pores. In this dissertation, single crystalline and core-shell germanium nanowires are synthesized using indium and bismuth as catalyst in a chemical vapor deposition procedure with germane (GeH{sub 4}) as growth precursor. A systematic growth study has been performed to obtain high aspect-ratio germanium nanowires. The influence of the growth conditions on the final morphology and the crystalline structure has been determined via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). In the case of indium catalyzed germanium nanowires, two different structures were identified: single crystalline and crystalline core-amorphous shell. The preferential growth axis of both kinds of nanowires is along the [110] direction. The occurrence of the two morphologies was found to only depend on the nanowire dimension. In the case of bismuth

An open-access mobile compatible electronic patient register for rheumatic heart disease (‘eRegister’) based on the World Heart Federation’s framework for patient registers

Science.gov (United States)

van Dam, Joris; Tadmor, Brigitta; Spector, Jonathan; Musuku, John; Zühlke, Liesl J; Zühlke, Liesl J; Engel, Mark E; Mayosi, Bongani M; Nestle, Nick

2015-01-01

Summary Background Rheumatic heart disease (RHD) remains a major disease burden in low-resource settings globally. Patient registers have long been recognised to be an essential instrument in RHD control and elimination programmes, yet to date rely heavily on paper-based data collection and non-networked data-management systems, which limit their functionality. Objectives To assess the feasibility and potential benefits of producing an electronic RHD patient register. Methods We developed an eRegister based on the World Heart Federation’s framework for RHD patient registers using CommCare, an open-source, cloud-based software for health programmes that supports the development of customised data capture using mobile devices. Results The resulting eRegistry application allows for simultaneous data collection and entry by field workers using mobile devices, and by providers using computer terminals in clinics and hospitals. Data are extracted from CommCare and are securely uploaded into a cloud-based database that matches the criteria established by the WHF framework. The application can easily be tailored to local needs by modifying existing variables or adding new ones. Compared with traditional paper-based data-collection systems, the eRegister reduces the risk of data error, synchronises in real-time, improves clinical operations and supports management of field team operations. Conclusions The user-friendly eRegister is a low-cost, mobile, compatible platform for RHD treatment and prevention programmes based on materials sanctioned by the World Heart Federation. Readily adaptable to local needs, this paperless RHD patient register program presents many practical benefits. PMID:26444995

Self-organized patterns along sidewalls of iron silicide nanowires on Si(110) and their origin

Energy Technology Data Exchange (ETDEWEB)

Das, Debolina; Mahato, J. C.; Bisi, Bhaskar; Dev, B. N., E-mail: msbnd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata 700032 (India); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

2014-11-10

Iron silicide (cubic FeSi{sub 2}) nanowires have been grown on Si(110) by reactive deposition epitaxy and investigated by scanning tunneling microscopy and scanning/transmission electron microscopy. On an otherwise uniform nanowire, a semi-periodic pattern along the edges of FeSi{sub 2} nanowires has been discovered. The origin of such growth patterns has been traced to initial growth of silicide nanodots with a pyramidal Si base at the chevron-like atomic arrangement of a clean reconstructed Si(110) surface. The pyramidal base evolves into a comb-like structure along the edges of the nanowires. This causes the semi-periodic structure of the iron silicide nanowires along their edges.

Templated Control of Au nanospheres in Silica Nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2007-03-15

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

PREFACE: Synthesis and integration of nanowires

Science.gov (United States)

Samuelson, L.

2006-06-01

The field of semiconductor nanowires has attracted much attention in recent years, from the areas of basic materials science, advanced characterization and technology, as well as from the perspective of the applications of nanowires. Research on large-sized whiskers and wires had already begun in the 1960s with the pioneering work of Wagner, as well as by other researchers. It was, however, in the early 1990s that Kenji Hiruma at Hitachi Central Research Laboratories in Japan first succeeded in developing methods for the growth of nanowires with dimensions on the scale of 10-100 nm, thereby initiating the field of growth and applications of nanowires, with a strong emphasis on epitaxial nucleation of nanowires on a single-crystalline substrate. Starting from the mid-1990s, the field developed very rapidly with the number of papers on the subject growing from ten per year to several thousand papers on the subject published annually today, although with a rather generous definition of the concept of nanowires. With this rapid development we have seen many new and different approaches to the growth of nanowires, technological advances leading to a more well-controlled formation of nanowires, new innovative methods for the characterization of structures, as well as a wealth of approaches towards the use of nanowires in electronics, photonics and sensor applications. This issue contains contributions from many different laboratories, each adding significant detail to the development of the field of research. The contributions cover issues such as basic growth, advanced characterization and technology, and application of nanowires. I would like to acknowledge the shared responsibilities for this special issue of Nanotechnology on the synthesis and integration of nanowires with my co-Editors, S Tong Lee and M Sunkara, as well as the highly professional support from Dr Nina Couzin, Dr Ian Forbes and the Nanotechnology team from the Institute of Physics Publishing.

Direct Photonic-Plasmonic Coupling and Routing in Single Nanowires

Energy Technology Data Exchange (ETDEWEB)

Yan, Rouxue; Pausauskie, Peter; Huang, Jiaxing; Yang, Piedong

2009-10-20

Metallic nanoscale structures are capable of supporting surface plasmon polaritons (SPPs), propagating collective electron oscillations with tight spatial confinement at the metal surface. SPPs represent one of the most promising structures to beat the diffraction limit imposed by conventional dielectric optics. Ag nano wires have drawn increasing research attention due to 2D sub-100 nm mode confinement and lower losses as compared with fabricated metal structures. However, rational and versatile integration of Ag nanowires with other active and passive optical components, as well as Ag nanowire based optical routing networks, has yet to be achieved. Here, we demonstrate that SPPs can be excited simply by contacting a silver nanowire with a SnO2 nanoribbon that serves both as an unpolarized light source and a dielectric waveguide. The efficient coupling makes it possible to measure the propagation-distance-dependent waveguide spectra and frequency-dependent propagation length on a single Ag nanowire. Furthermore, we have demonstrated prototypical photonic-plasmonic routing devices, which are essential for incorporating low-loss Ag nanowire waveguides as practical components into high-capacity photonic circuits.

Electrospinning synthesis of superconducting BSCCO nanowires

International Nuclear Information System (INIS)

Duarte, Edgar A.; Quintero, Pedro A.; Meisel, Mark W.; Nino, Juan C.

2013-01-01

Highlights: •Bi 2 Sr 2 CaCu 2 O 8+x nanowires 150 nm to 250 nm thick are synthesized using the electrospinning. •Bi 2 Sr 2 CaCu 2 O 8+x nanowires are obtained after a heat treatment at 850 °C. •Bi 2 Sr 2 CaCu 2 O 8+x nanowires show a T c = 78.7 K consistent with bulk superconductor behavior. -- Abstract: This paper presents the synthesis and characterization of Bi 2 Sr 2 CaCu 2 O 8+x superconducting nanowires. Bi 2 Sr 2 CaCu 2 O 8+x nanowires with a T c = 78.7 K are synthesized using the electrospinning process employing sol–gel precursors. A sol–gel methodology is used to obtain a homogeneous PVP solution containing Bi, Sr, Ca, and Cu acetates. Mats of randomly oriented nanowires and aligned nanowires are also collected. After a heat treatment at 850 °C in ambient atmosphere using heating rates of 100 and 400 °C/h, fully crystallized Bi 2 Sr 2 CaCu 2 O 8+x nanowires are obtained. The morphology, microstructure, and crystal structure of these nanowires are then examined to reveal a rectangular morphology having typical wire thickness in the range of 150–250 nm, and a wire width between 400 and 600 nm. DC magnetization studies are conducted to investigate the critical transition temperature (T c ) of Bi 2 Sr 2 CaCu 2 O 8+x nanowires and to compare their magnetic properties to those of bulk Bi 2 Sr 2 CaCu 2 O 8+x powder. The T c for the commercial powder is observed at 78.6 K, and that of the obtained nanowires at 78.7 K. These results point to the superconducting nature of Bi 2 Sr 2 CaCu 2 O 8+x nanowires, and the potential of the electrospinning process for the synthesis of this superconductor material

The ITO-capped WO{sub 3} nanowires biosensor based on field-effect transistor in label-free protein sensing

Energy Technology Data Exchange (ETDEWEB)

Shariati, Mohsen [Sharif University of Technology, Institute for Nanoscience and Nanotechnology, Tehran (Iran, Islamic Republic of)

2017-05-15

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

Micromagnetic simulations of cylindrical magnetic nanowires

KAUST Repository

Ivanov, Yurii P.

2015-05-27

This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.

The growth of silica and silica-clad nanowires using a solid-state reaction mechanism on Ti, Ni and SiO2 layers

International Nuclear Information System (INIS)

Sharma, Parul; Anguita, J V; Stolojan, V; Henley, S J; Silva, S R P

2010-01-01

A large area compatible and solid-state process for growing silica nanowires is reported using nickel, titanium and silicon dioxide layers on silicon. The silica nanowires also contain silicon, as indicated by Raman spectroscopy. The phonon confinement model is employed to measure the diameter of the Si rich tail for our samples. The measured Raman peak shift and full width at half-maximum variation with the nanowire diameter qualitatively match with data available in the literature. We have investigated the effect of the seedbed structure on the nanowires, and the effect of using different gas conditions in the growth stages. From this, we have obtained the growth mechanism, and deduced the role of each individual substrate seedbed layer in the growth of the nanowires. We report a combined growth mechanism, where the growth is initiated by a solid-liquid-solid process, which is then followed by a vapour-liquid-solid process. We also report on the formation of two distinct structures of nanowires (type I and type II). The growth of these can be controlled by the use of titanium in the seedbed. We also observe that the diameter of the nanowires exhibits an inverse relation with the catalyst thickness.

Magnetostatic Interaction in Fe-Co Nanowires

Directory of Open Access Journals (Sweden)

Laura Elbaile

2012-01-01

Full Text Available Arrays of Fe-Co alloy nanowires with diameter around 35 nm and several micrometers in length have been synthesized by codepositing Fe and Co into porous anodic alumina. The morphology, structure, and magnetic properties of the nanowires (hysteresis loops and remanence curves were characterized by SEM, TEM, X-ray diffraction (XRD, and VSM, respectively. The XRD patterns indicate that the Fe-Co nanowires present a body-centered cubic (bcc structure and a preferred (110 orientation perpendicular to the template surface. From the hysteresis loops obtained with the magnetic field applied in the axis direction of the nanowires, we can observe that the coercive field slightly decreases when the nanowire length increases. This magnetic behaviour is analyzed considering the shape anisotropy and the dipolar interactions among nanowires.

Modelling the acid/base 1H NMR chemical shift limits of metabolites in human urine.

Science.gov (United States)

Tredwell, Gregory D; Bundy, Jacob G; De Iorio, Maria; Ebbels, Timothy M D

2016-01-01

Despite the use of buffering agents the 1 H NMR spectra of biofluid samples in metabolic profiling investigations typically suffer from extensive peak frequency shifting between spectra. These chemical shift changes are mainly due to differences in pH and divalent metal ion concentrations between the samples. This frequency shifting results in a correspondence problem: it can be hard to register the same peak as belonging to the same molecule across multiple samples. The problem is especially acute for urine, which can have a wide range of ionic concentrations between different samples. To investigate the acid, base and metal ion dependent 1 H NMR chemical shift variations and limits of the main metabolites in a complex biological mixture. Urine samples from five different individuals were collected and pooled, and pre-treated with Chelex-100 ion exchange resin. Urine samples were either treated with either HCl or NaOH, or were supplemented with various concentrations of CaCl 2 , MgCl 2 , NaCl or KCl, and their 1 H NMR spectra were acquired. Nonlinear fitting was used to derive acid dissociation constants and acid and base chemical shift limits for peaks from 33 identified metabolites. Peak pH titration curves for a further 65 unidentified peaks were also obtained for future reference. Furthermore, the peak variations induced by the main metal ions present in urine, Na + , K + , Ca 2+ and Mg 2+ , were also measured. These data will be a valuable resource for 1 H NMR metabolite profiling experiments and for the development of automated metabolite alignment and identification algorithms for 1 H NMR spectra.

State-Transition-Aware Spilling Heuristic for MLC STT-RAM-Based Registers

Directory of Open Access Journals (Sweden)

Yuanhui Ni

2017-01-01

Full Text Available Multilevel Cell Spin-Transfer Torque Random Access Memory (MLC STT-RAM is a promising nonvolatile memory technology to build registers for its natural immunity to electromagnetic radiation in rad-hard space environment. Unlike traditional SRAM-based registers, MLC STT-RAM exhibits unbalanced write state transitions due to the fact that the magnetization directions of hard and soft domains cannot be flipped independently. This feature leads to nonuniform costs of write states in terms of latency and energy. However, current SRAM-targeting register allocations do not have a clear understanding of the impact of the different write state-transition costs. As a result, those approaches heuristically select variables to be spilled without considering the spilling priority imposed by MLC STT-RAM. Aiming to address this limitation, this paper proposes a state-transition-aware spilling cost minimization (SSCM policy, to save power when MLC STT-RAM is employed in register design. Specifically, the spilling cost model is first constructed according to the linear combination of different state-transition frequencies. Directed by the proposed cost model, the compiler picks up spilling candidates to achieve lower power and higher performance. Experimental results show that the proposed SSCM technique can save energy by 19.4% and improve the lifetime by 23.2% of MLC STT-RAM-based register design.

Adaptation of Shift Sequence Based Method for High Number in Shifts Rostering Problem for Health Care Workers

Directory of Open Access Journals (Sweden)

Mindaugas Liogys

2013-08-01

Full Text Available Purpose—is to investigate a shift sequence-based approach efficiency then problem consisting of a high number of shifts.Research objectives:• Solve health care workers rostering problem using a shift sequence based method.• Measure its efficiency then number of shifts increases.Design/methodology/approach—Usually rostering problems are highly constrained. Constraints are classified to soft and hard constraints. Soft and hard constraints of the problem are additionally classified to: sequence constraints, schedule constraints and roster constraints. Sequence constraints are considered when constructing shift sequences. Schedule constraints are considered when constructing a schedule. Roster constraints are applied, then constructing overall solution, i.e. combining all schedules.Shift sequence based approach consists of two stages:• Shift sequences construction,• The construction of schedules.In the shift sequences construction stage, the shift sequences are constructed for each set of health care workers of different skill, considering sequence constraints. Shifts sequences are ranked by their penalties for easier retrieval in later stage.In schedules construction stage, schedules for each health care worker are constructed iteratively, using the shift sequences produced in stage 1.Shift sequence based method is an adaptive iterative method where health care workers who received the highest schedule penalties in the last iteration are scheduled first at the current iteration.During the roster construction, and after a schedule has been generated for the current health care worker, an improvement method based on an efficient greedy local search is carried out on the partial roster. It simply swaps any pair of shifts between two health care workers in the (partial roster, as long as the swaps satisfy hard constraints and decrease the roster penalty.Findings—Using shift sequence method for solving health care workers rostering problem

Adaptation of Shift Sequence Based Method for High Number in Shifts Rostering Problem for Health Care Workers

Directory of Open Access Journals (Sweden)

Mindaugas Liogys

2011-08-01

Full Text Available Purpose—is to investigate a shift sequence-based approach efficiency then problem consisting of a high number of shifts. Research objectives:• Solve health care workers rostering problem using a shift sequence based method.• Measure its efficiency then number of shifts increases. Design/methodology/approach—Usually rostering problems are highly constrained.Constraints are classified to soft and hard constraints. Soft and hard constraints of the problem are additionally classified to: sequence constraints, schedule constraints and roster constraints. Sequence constraints are considered when constructing shift sequences. Schedule constraints are considered when constructing a schedule. Roster constraints are applied, then constructing overall solution, i.e. combining all schedules.Shift sequence based approach consists of two stages:• Shift sequences construction,• The construction of schedules.In the shift sequences construction stage, the shift sequences are constructed for each set of health care workers of different skill, considering sequence constraints. Shifts sequences are ranked by their penalties for easier retrieval in later stage.In schedules construction stage, schedules for each health care worker are constructed iteratively, using the shift sequences produced in stage 1. Shift sequence based method is an adaptive iterative method where health care workers who received the highest schedule penalties in the last iteration are scheduled first at the current iteration. During the roster construction, and after a schedule has been generated for the current health care worker, an improvement method based on an efficient greedy local search is carried out on the partial roster. It simply swaps any pair of shifts between two health care workers in the (partial roster, as long as the swaps satisfy hard constraints and decrease the roster penalty.Findings—Using shift sequence method for solving health care workers rostering

Dramatically enhanced ultraviolet photosensing mechanism in a n-ZnO nanowires/i-MgO/n-Si structure with highly dense nanowires and ultrathin MgO layers

International Nuclear Information System (INIS)

Kim, Dong Chan; Jung, Byung Oh; Cho, Hyung Koun; Lee, Ju Ho; Lee, Jeong Yong; Lee, Jun Hee

2011-01-01

This study reports that the visible-blind ultraviolet (UV) photodetecting properties of ZnO nanowire based photodetectors were remarkably improved by introducing ultrathin insulating MgO layers between the ZnO nanowires and Si substrates. All layers were grown without pause by metal organic chemical vapor deposition and the density and vertical arrangement of the ZnO nanowires were strongly dependent on the thickness of the MgO layers. The sample in which an MgO layer with a thickness of 8 nm was inserted had high density nanowires with a vertical alignment and showed dramatically improved UV photosensing performance (photo-to-dark current ratio = 1344.5 and recovery time = 350 ms). The photoresponse spectrum revealed good visible-blind UV detectivity with a sharp cut off at 378 nm and a high UV/visible rejection ratio. A detailed discussion regarding the developed UV photosensing mechanism from the introduction of the i-MgO layers and highly dense nanowires in the n-ZnO nanowires/i-MgO/n-Si substrates structure is presented in this work.

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.

Silicon nanowire hybrid photovoltaics

KAUST Repository

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

2010-01-01

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

Epitaxy-enabled vapor-liquid-solid growth of tin-doped indium oxide nanowires with controlled orientations

KAUST Repository

Shen, Youde

2014-08-13

Controlling the morphology of nanowires in bottom-up synthesis and assembling them on planar substrates is of tremendous importance for device applications in electronics, photonics, sensing and energy conversion. To date, however, there remain challenges in reliably achieving these goals of orientation-controlled nanowire synthesis and assembly. Here we report that growth of planar, vertical and randomly oriented tin-doped indium oxide (ITO) nanowires can be realized on yttria-stabilized zirconia (YSZ) substrates via the epitaxy-assisted vapor-liquid-solid (VLS) mechanism, by simply regulating the growth conditions, in particular the growth temperature. This robust control on nanowire orientation is facilitated by the small lattice mismatch of 1.6% between ITO and YSZ. Further control of the orientation, symmetry and shape of the nanowires can be achieved by using YSZ substrates with (110) and (111), in addition to (100) surfaces. Based on these insights, we succeed in growing regular arrays of planar ITO nanowires from patterned catalyst nanoparticles. Overall, our discovery of unprecedented orientation control in ITO nanowires advances the general VLS synthesis, providing a robust epitaxy-based approach toward rational synthesis of nanowires. © 2014 American Chemical Society.

Ultrabroad linewidth orange-emitting nanowires LED for high CRI laser-based white lighting and gigahertz communications

KAUST Repository

Janjua, Bilal; Ng, Tien Khee; Zhao, Chao; Oubei, Hassan M.; Shen, Chao; Prabaswara, Aditya; Alias, Mohd Sharizal; Alhamoud, Abdullah Ali; Alatawi, Abdullah Awaad; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

2016-01-01

intensity- and bandwidth-tunable for high color-quality remained unexplored. In this paper, we present for the first time, the proof-of-concept of the generation of high-quality white light using an InGaN-based orange nanowires (NWs) LED grown on silicon

The influence of surfaces on the transient terahertz conductivity and electron mobility of GaAs nanowires

International Nuclear Information System (INIS)

Joyce, Hannah J; Baig, Sarwat A; Parkinson, Patrick; Davies, Christopher L; Boland, Jessica L; Herz, Laura M; Johnston, Michael B; Tan, H Hoe; Jagadish, Chennupati

2017-01-01

Bare unpassivated GaAs nanowires feature relatively high electron mobilities (400–2100 cm 2 V −1 s −1 ) and ultrashort charge carrier lifetimes (1–5 ps) at room temperature. These two properties are highly desirable for high speed optoelectronic devices, including photoreceivers, modulators and switches operating at microwave and terahertz frequencies. When engineering these GaAs nanowire-based devices, it is important to have a quantitative understanding of how the charge carrier mobility and lifetime can be tuned. Here we use optical-pump–terahertz-probe spectroscopy to quantify how mobility and lifetime depend on the nanowire surfaces and on carrier density in unpassivated GaAs nanowires. We also present two alternative frameworks for the analysis of nanowire photoconductivity: one based on plasmon resonance and the other based on Maxwell–Garnett effective medium theory with the nanowires modelled as prolate ellipsoids. We find the electron mobility decreases significantly with decreasing nanowire diameter, as charge carriers experience increased scattering at nanowire surfaces. Reducing the diameter from 50 nm to 30 nm degrades the electron mobility by up to 47%. Photoconductivity dynamics were dominated by trapping at saturable states existing at the nanowire surface, and the trapping rate was highest for the nanowires of narrowest diameter. The maximum surface recombination velocity, which occurs in the limit of all traps being empty, was calculated as 1.3  ×  10 6 cm s −1 . We note that when selecting the optimum nanowire diameter for an ultrafast device, there is a trade-off between achieving a short lifetime and a high carrier mobility. To achieve high speed GaAs nanowire devices featuring the highest charge carrier mobilities and shortest lifetimes, we recommend operating the devices at low charge carrier densities. (paper)

Functionalised zinc oxide nanowire gas sensors: Enhanced NO(2) gas sensor response by chemical modification of nanowire surfaces.

Science.gov (United States)

Waclawik, Eric R; Chang, Jin; Ponzoni, Andrea; Concina, Isabella; Zappa, Dario; Comini, Elisabetta; Motta, Nunzio; Faglia, Guido; Sberveglieri, Giorgio

2012-01-01

Surface coating with an organic self-assembled monolayer (SAM) can enhance surface reactions or the absorption of specific gases and hence improve the response of a metal oxide (MOx) sensor toward particular target gases in the environment. In this study the effect of an adsorbed organic layer on the dynamic response of zinc oxide nanowire gas sensors was investigated. The effect of ZnO surface functionalisation by two different organic molecules, tris(hydroxymethyl)aminomethane (THMA) and dodecanethiol (DT), was studied. The response towards ammonia, nitrous oxide and nitrogen dioxide was investigated for three sensor configurations, namely pure ZnO nanowires, organic-coated ZnO nanowires and ZnO nanowires covered with a sparse layer of organic-coated ZnO nanoparticles. Exposure of the nanowire sensors to the oxidising gas NO(2) produced a significant and reproducible response. ZnO and THMA-coated ZnO nanowire sensors both readily detected NO(2) down to a concentration in the very low ppm range. Notably, the THMA-coated nanowires consistently displayed a small, enhanced response to NO(2) compared to uncoated ZnO nanowire sensors. At the lower concentration levels tested, ZnO nanowire sensors that were coated with THMA-capped ZnO nanoparticles were found to exhibit the greatest enhanced response. ΔR/R was two times greater than that for the as-prepared ZnO nanowire sensors. It is proposed that the ΔR/R enhancement in this case originates from the changes induced in the depletion-layer width of the ZnO nanoparticles that bridge ZnO nanowires resulting from THMA ligand binding to the surface of the particle coating. The heightened response and selectivity to the NO(2) target are positive results arising from the coating of these ZnO nanowire sensors with organic-SAM-functionalised ZnO nanoparticles.

Highly sensitive uric acid biosensor based on individual zinc oxide micro/nanowires

International Nuclear Information System (INIS)

Zhao, Yanguang; Yan, Xiaoqin; Kang, Zhuo; Lin, Pei; Fang, Xiaofei; Lei, Yang; Ma, Siwei; Zhang, Yue

2013-01-01

We describe the use of individual zinc oxide (ZnO) micro/nanowires in an electrochemical biosensor for uric acid. The wires were synthesized by chemical vapor deposition and possess uniform morphology and high crystallinity as revealed by scanning electron microscopy, X-ray diffraction, and photoluminescence studies. The enzyme uricase was then immobilized on the surface of the ZnO micro/nanowires by physical adsorption, and this was proven by Raman spectroscopy and fluorescence microscopy. The resulting uric acid biosensor undergoes fast electron transfer between the active site of the enzyme and the surface of the electrode. It displays high sensitivity (89.74 μA cm −2 mM −1 ) and a wide linear analytical range (between 0.1 mM and 0.59 mM concentrations of uric acid). This study also demonstrates the potential of the use of individual ZnO micro/nanowires for the construction of highly sensitive nano-sized biosensors. (author)

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.

Structural and tunneling properties of Si nanowires

KAUST Repository

Montes Muñ oz, Enrique; Gkionis, Konstantinos; Rungger, Ivan; Sanvito, Stefano; Schwingenschlö gl, Udo

2013-01-01

We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green's function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.

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

2014-01-01

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. PMID:25156820

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

On The Designed And Constructed Feedback Shift-Register Encoder

African Journals Online (AJOL)

An encoder capable of cyclical shifting of data, and which can therefore be used for Bose-Chaudhuri and Hocquenghem (BCH) coding, has been designed and constructed using discrete components. It comprises basically four bistable multivibrators and an exclusive-OR device. On completion, the encoder performed ...

Initialization of a spin qubit in a site-controlled nanowire quantum dot

International Nuclear Information System (INIS)

Lagoudakis, Konstantinos G; McMahon, Peter L; Fischer, Kevin A; Müller, Kai; Yamamoto, Yoshihisa; Vučković, Jelena; Puri, Shruti; Dan Dalacu; Poole, Philip J; Reimer, Michael E; Zwiller, Val

2016-01-01

A fault-tolerant quantum repeater or quantum computer using solid-state spin-based quantum bits will likely require a physical implementation with many spins arranged in a grid. Self-assembled quantum dots (QDs) have been established as attractive candidates for building spin-based quantum information processing devices, but such QDs are randomly positioned, which makes them unsuitable for constructing large-scale processors. Recent efforts have shown that QDs embedded in nanowires can be deterministically positioned in regular arrays, can store single charges, and have excellent optical properties, but so far there have been no demonstrations of spin qubit operations using nanowire QDs. Here we demonstrate optical pumping of individual spins trapped in site-controlled nanowire QDs, resulting in high-fidelity spin-qubit initialization. This represents the next step towards establishing spins in nanowire QDs as quantum memories suitable for use in a large-scale, fault-tolerant quantum computer or repeater based on all-optical control of the spin qubits. (paper)

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.

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.

Electrodeposition of rhenium-tin nanowires

International Nuclear Information System (INIS)

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

2011-01-01

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

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.)

Integration, gap formation, and sharpening of III-V heterostructure nanowires by selective etching

DEFF Research Database (Denmark)

Kallesoe, C.; Mølhave, Kristian; Larsen, K. F.

2010-01-01

Epitaxial growth of heterostructure nanowires allows for the definition of narrow sections with specific semiconductor composition. The authors demonstrate how postgrowth engineering of III-V heterostructure nanowires using selective etching can form gaps, sharpening of tips, and thin sections...... lithography is used for deposition of catalyst particles on trench sidewalls and the lateral growth of III-V nanowires is achieved from such catalysts. The selectivity of a bromine-based etch on gallium arsenide segments in gallium phosphide nanowires is examined, using a hydrochloride etch to remove the III...

Gold nanowires and the effect of impurities

Directory of Open Access Journals (Sweden)

Novaes Frederico

2006-01-01

Full Text Available AbstractMetal nanowires and in particular gold nanowires have received a great deal of attention in the past few years. Experiments on gold nanowires have prompted theory and simulation to help answer questions posed by these studies. Here we present results of computer simulations for the formation, evolution and breaking of very thin Au nanowires. We also discuss the influence of contaminants, such as atoms and small molecules, and their effect on the structural and mechanical properties of these nanowires.

Electric Conductivity of Phosphorus Nanowires

International Nuclear Information System (INIS)

Jing-Xiang, Zhang; Hui, Li; Xue-Qing, Zhang; Kim-Meow, Liew

2009-01-01

We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

Electronic transport in narrow-gap semiconductor nanowires

International Nuclear Information System (INIS)

Bloemers, Christian

2012-01-01

from the field-effect measurements due to the influence of surface states. The homogeneity in transport characteristics of the InN nanowires allowed for an accurate analysis of the diameter dependence of the nanowire resistivity. The effect of donor deactivation has been found to increase the resistivity of InN nanowires with small diameters. Furthermore, a quantum confinement effect has been observed in GaAs/InAs core/shell nanowires. For very low shell thicknesses below 10 nm a drastic resistivity increase has been found. Simulations with a self consistent Schroedinger-Poisson solver confirmed the interpretation in terms of quantum confinement. A further major topic of this work has been the analysis of phase coherent transport at low temperatures. In particular, universal conductance fluctuations have been analyzed and a consistent method to determine the phase coherence length quantitatively has been developed. In addition, transport measurements on GaAs/InAs core/shell nanowires with a magnetic field applied parallel to the wire axis demonstrated Aharonov-Bohm-type conductance oscillations. An explanation in terms of coherent angular momentum quantum states in the conductive InAs shell has been developed to interpret these oscillations. To conclude, both room temperature and low temperature measurements allowed gaining insights into basic classical as well as quantum transport properties of nanowires. In the face of a future application of nanowires in quantum information processing or their use in so-called phase-based switching devices, valuable information is provided within this work. Furthermore, the room temperature results show that for application of nanowires in electronic devices, both the crystal structure and the surface conditions have to be controlled. Here, it will be inevitable for future progress to achieve a controlled passivation of the wire surfaces for defined and stable surface conditions. Furthermore, a more detailed investigation of the

Electronic transport in narrow-gap semiconductor nanowires

Energy Technology Data Exchange (ETDEWEB)

Bloemers, Christian

2012-10-19

from the field-effect measurements due to the influence of surface states. The homogeneity in transport characteristics of the InN nanowires allowed for an accurate analysis of the diameter dependence of the nanowire resistivity. The effect of donor deactivation has been found to increase the resistivity of InN nanowires with small diameters. Furthermore, a quantum confinement effect has been observed in GaAs/InAs core/shell nanowires. For very low shell thicknesses below 10 nm a drastic resistivity increase has been found. Simulations with a self consistent Schroedinger-Poisson solver confirmed the interpretation in terms of quantum confinement. A further major topic of this work has been the analysis of phase coherent transport at low temperatures. In particular, universal conductance fluctuations have been analyzed and a consistent method to determine the phase coherence length quantitatively has been developed. In addition, transport measurements on GaAs/InAs core/shell nanowires with a magnetic field applied parallel to the wire axis demonstrated Aharonov-Bohm-type conductance oscillations. An explanation in terms of coherent angular momentum quantum states in the conductive InAs shell has been developed to interpret these oscillations. To conclude, both room temperature and low temperature measurements allowed gaining insights into basic classical as well as quantum transport properties of nanowires. In the face of a future application of nanowires in quantum information processing or their use in so-called phase-based switching devices, valuable information is provided within this work. Furthermore, the room temperature results show that for application of nanowires in electronic devices, both the crystal structure and the surface conditions have to be controlled. Here, it will be inevitable for future progress to achieve a controlled passivation of the wire surfaces for defined and stable surface conditions. Furthermore, a more detailed investigation of the

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

Science.gov (United States)

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

2017-03-01

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

Giant Faraday Rotation of High-Order Plasmonic Modes in Graphene-Covered Nanowires.

Science.gov (United States)

Kuzmin, Dmitry A; Bychkov, Igor V; Shavrov, Vladimir G; Temnov, Vasily V

2016-07-13

Plasmonic Faraday rotation in nanowires manifests itself in the rotation of the spatial intensity distribution of high-order surface plasmon polariton (SPP) modes around the nanowire axis. Here we predict theoretically the giant Faraday rotation for SPPs propagating on graphene-coated magneto-optically active nanowires. Upon the reversal of the external magnetic field pointing along the nanowire axis some high-order plasmonic modes may be rotated by up to ∼100° on the length scale of about 500 nm at mid-infrared frequencies. Tuning the carrier concentration in graphene by chemical doping or gate voltage allows for controlling SPP-properties and notably the rotation angle of high-order azimuthal modes. Our results open the door to novel plasmonic applications ranging from nanowire-based Faraday isolators to the magnetic control in quantum-optical applications.

A Performance Survey on Stack-based and Register-based Virtual Machines

OpenAIRE

Fang, Ruijie; Liu, Siqi

2016-01-01

Virtual machines have been widely adapted for high-level programming language implementations and for providing a degree of platform neutrality. As the overall use and adaptation of virtual machines grow, the overall performance of virtual machines has become a widely-discussed topic. In this paper, we present a survey on the performance differences of the two most widely adapted types of virtual machines - the stack-based virtual machine and the register-based virtual machine - using various...

Production of a pseudo-random square wave using a shift register with binary feedbacks; Generation d'un creneau pseudo-aleatoire par un registre a decalage a contre-reaction binaire

Energy Technology Data Exchange (ETDEWEB)

Stern, T E; Cazemajou, J; Macherez, B; Valat, J; Vignon, A

1964-07-01

We summarize here the theoretical basis for the production of square wave having the values '1' or '0', the switching times being 'pseudo-random'. More precisely, the square-wave may or may not change value at regular time intervals of length {delta}, with probability approximately. 5 for each alternative. The wave-form is obtained by means of a shift-register having modulo-2 feedback. If the interval {delta} and the feedback connections are well chosen, it is possible to produce a waveform whose autocorrelation function is very close to a Dirac delta function. The square-wave therefore behaves like a quantized white noise, which has very interesting properties in cross-correlation techniques. (authors) [French] On resume ici les bases theoriques permettant d'obtenir un creneau prenant les valeurs '1' ou '0', les instants de commutation etant pseudo-aleatoires. Plus exactement, le creneau a la possibilite de changer (ou de ne pas changer) d'etat a intervalles de temps reguliers, separes par intervalle elementaire {delta}, chacune des deux possibilites possedant une probabilite d'apparition tres voisine de 0,5. Le creneau est obtenu par un registre a decalage (shift register) a contre-reactions logiques modulo-2. Si l'intervalle {delta} et les contre-reactions sont judicieusement choisis, il est possible d'obtenir pour le creneau une fonction d'autocorrelation triangulaire tres voisine d'une impulsion de Dirac. Par suite le creneau se comporte comme un bruit blanc quantifie possedant de tres interessantes proprietes pour les techniques statistiques d'intercorrelation. (auteurs)

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-01

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

Double resonance Raman effects in InN nanowires

Energy Technology Data Exchange (ETDEWEB)

Domenech-Amador, N.; Cusco, R.; Artus, L. [Institut Jaume Almera, Consell Superior d' Investigacions Cientifiques (CSIC), Lluis Sole i Sabaris s.n., Barcelona, Catalonia (Spain); Calarco, R. [Institute of Bio- and Nanosystems, Research Center Juelich GmbH, Juelich (Germany); Paul-Drude-Institut fuer Festkoerperelektronik, Berlin (Germany); Yamaguchi, T.; Nanishi, Y. [Faculty of Science and Engineering, Ritsumeikan University, Noji-Higashi, Kusatsu, Shiga 525-8577 (Japan)

2012-04-15

We study the excitation wavelength dependence of the Raman spectra of InN nanowires. The E{sub 1}(LO) phonon mode, which is detected in backscattering configuration because of light entering through lateral faces, exhibits an upward frequency shift that can be explained by Martin's double resonance. The E{sub 1} (LO)/E{sub 2}{sup h} intensity ratio increases with the excitation wavelength more rapidly than the A{sub 1}(LO)/E{sub 2}{sup h} ratio measured in InN thin films. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Complex Electric-Field Induced Phenomena in Ferroelectric/Antiferroelectric Nanowires

Science.gov (United States)

Herchig, Ryan Christopher

Perovskite ferroelectrics and antiferroelectrics have attracted a lot of attention owing to their potential for device applications including THz sensors, solid state cooling, ultra high density computer memory, and electromechanical actuators to name a few. The discovery of ferroelectricity at the nanoscale provides not only new and exciting possibilities for device miniaturization, but also a way to study the fundamental physics of nanoscale phenomena in these materials. Ferroelectric nanowires show a rich variety of physical characteristics which are advantageous to the design of nanoscale ferroelectric devices such as exotic dipole patterns, a strong dependence of the polarization and phonon frequencies on the electrical and mechanical boundary conditions, as well as a dependence of the transition temperatures on the diameter of the nanowire. Antiferroelectricity also exists at the nanoscale and, due to the proximity in energy of the ferroelectric and antiferroelectric phases, a phase transition from the ferroelectric to the antiferroelectric phase can be facilitated through the application of the appropriate mechanical and electrical boundary conditions. While much progress has been made over the past several decades to understand the nature of ferroelectricity/antiferroelectricity in nanowires, many questions remain unanswered. In particular, little is known about how the truncated dimensions affect the soft mode frequency dynamics or how various electrical and mechanical boundary conditions might change the nature of the phase transitions in these ferroelectric nanowires. Could nanowires offer a distinct advantage for solid state cooling applications? Few studies have been done to elucidate the fundamental physics of antiferroelectric nanowires. How the polarization in ferroelectric nanowires responds to a THz electric field remains relatively underexplored as well. In this work, the aim is to to develop and use computational tools that allow first-principles-based

Magnetic and superconducting nanowires

DEFF Research Database (Denmark)

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

2005-01-01

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

High-performance asymmetric supercapacitors based on core/shell cobalt oxide/carbon nanowire arrays with enhanced electrochemical energy storage

International Nuclear Information System (INIS)

Pan, G.X.; Xia, X.H.; Cao, F.; Chen, J.; Tang, P.S.; Zhang, Y.J.; Chen, H.F.

2014-01-01

Graphical abstract: - Highlights: • We prepared a self-supported porous Co 3 O 4 /C core/shell nanowire array. • Core/shell nanowire array showed high pseudo-capacitive properties. • Core/shell array structure was favorable for fast ion and electron transfer. - Abstract: High-reactivity electrode materials are indispensible for developing high-performance electrochemical energy storage devices. Herein, we report self-supported core/shell Co 3 O 4 /C nanowire arrays by using hydrothermal synthesis and chemical vapor deposition methods. A uniform and thin carbon shell is coated on the surface of Co 3 O 4 nanowire forming core/shell nanowires with diameters of ∼100 nm. Asymmetric supercapacitors have been assembled with the core/shell Co 3 O 4 /C nanowire arrays as the positive electrode and activated carbon (AC) as the negative electrode. The core/shell Co 3 O 4 /C nanowire arrays exhibit a specific capacity of 116 mAh g −1 at the working current of 100 mA (4 A g −1 ), and a long cycle life along with ∼ 92% retention after 8000 cycles at 4 A g −1 , higher than the unmodified Co 3 O 4 nanowire arrays (81 mAh g −1 at 4 A g −1 ). The introduction of uniform carbon layer into the core/shell structure is favorable for the enhancement of supercapacitor due to the improved electrical conductivity and reaction kinetics

On The Designed And Constructed Feedback Shift-Register Encoder

African Journals Online (AJOL)

Information transmission in noisy channels can be achieved with vanishingly small probability of error by proper coding of the information as long as the encoding rate is less than the channel capacity. An encoder capable of cyclical shifting of data, and which can therefore be used for Bose-Chaudhuri and Hocquenghem ...

Vertically aligned nanowires from boron-doped diamond.

Science.gov (United States)

Yang, Nianjun; Uetsuka, Hiroshi; Osawa, Eiji; Nebel, Christoph E

2008-11-01

Vertically aligned diamond nanowires with controlled geometrical properties like length and distance between wires were fabricated by use of nanodiamond particles as a hard mask and by use of reactive ion etching. The surface structure, electronic properties, and electrochemical functionalization of diamond nanowires were characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) as well as electrochemical techniques. AFM and STM experiments show that diamond nanowire etched for 10 s have wire-typed structures with 3-10 nm in length and with typically 11 nm spacing in between. The electrode active area of diamond nanowires is enhanced by a factor of 2. The functionalization of nanowire tips with nitrophenyl molecules is characterized by STM on clean and on nitrophenyl molecule-modified diamond nanowires. Tip-modified diamond nanowires are promising with respect to biosensor applications where controlled biomolecule bonding is required to improve chemical stability and sensing significantly.

Nanowire failure: long = brittle and short = ductile.

Science.gov (United States)

Wu, Zhaoxuan; Zhang, Yong-Wei; Jhon, Mark H; Gao, Huajian; Srolovitz, David J

2012-02-08

Experimental studies of the tensile behavior of metallic nanowires show a wide range of failure modes, ranging from ductile necking to brittle/localized shear failure-often in the same diameter wires. We performed large-scale molecular dynamics simulations of copper nanowires with a range of nanowire lengths and provide unequivocal evidence for a transition in nanowire failure mode with change in nanowire length. Short nanowires fail via a ductile mode with serrated stress-strain curves, while long wires exhibit extreme shear localization and abrupt failure. We developed a simple model for predicting the critical nanowire length for this failure mode transition and showed that it is in excellent agreement with both the simulation results and the extant experimental data. The present results provide a new paradigm for the design of nanoscale mechanical systems that demarcates graceful and catastrophic failure. © 2012 American Chemical Society

All-solid-state thin film battery based on well-aligned slanted LiCoO{sub 2} nanowires fabricated by glancing angle deposition

Energy Technology Data Exchange (ETDEWEB)

Yoon, Miyoung [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Seunghwan [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Daehee [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Joosun, E-mail: joosun@kist.re.kr [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Moon, Jooho, E-mail: jmoon@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

2017-08-01

Graphical abstract: We successfully fabricated well-aligned slanted LiCoO{sub 2} nanowires as a one-dimensional nanostructured cathode by glancing angle deposition to enhance the electrochemical performance of all-solid-state thin film batteries. - Highlights: • Well-aligned slanted LiCoO{sub 2} nanowires are fabricated by glancing angle deposition. • One-dimensional nanostructured LiCoO{sub 2} cathode enlarges the contact area. • All-solid-state thin film battery exhibits enhances rate capability and cycling stability. - Abstract: We fabricated all-solid-state thin film batteries based on well-aligned slanted LiCoO{sub 2} nanowires by glancing angle deposition, as a facile template-free method in order to increase the electrochemically active site, i.e., the contact area between the solid electrolyte and the electrode. A highly porous thin film composed of well-separated slanted LiCoO{sub 2} nanowires not only facilitates the penetration of solid electrolyte phase into the cathode, but also alleviates the thermally and mechanically induced stresses during post-annealing and electrochemical cycling. The all-solid-state thin film battery based on the well-aligned slanted LiCoO{sub 2} nanowires, whose contact area between electrolyte and electrode was three times as high as that of a dense thin film, could provide additional migration pathways for lithium ion diffusion due to the enlarged reaction sites. This resulted in enhanced electrochemical kinetics, thereby leading to better rate capability and long-term cyclic stability as compared to the dense LiCoO{sub 2} thin film.

Ballistic superconductivity in semiconductor nanowires

Science.gov (United States)

Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P.; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K.; van Veen, Jasper; de Moor, Michiel W. A.; Bommer, Jouri D. S.; van Woerkom, David J.; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P.A.M.; Quintero-Pérez, Marina; Cassidy, Maja C.; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo 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 superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices. PMID:28681843

Silicon nanowires for photovoltaic solar energy conversion.

Science.gov (United States)

Peng, Kui-Qing; Lee, Shuit-Tong

2011-01-11

Semiconductor nanowires are attracting intense interest as a promising material for solar energy conversion for the new-generation photovoltaic (PV) technology. In particular, silicon nanowires (SiNWs) are under active investigation for PV applications because they offer novel approaches for solar-to-electric energy conversion leading to high-efficiency devices via simple manufacturing. This article reviews the recent developments in the utilization of SiNWs for PV applications, the relationship between SiNW-based PV device structure and performance, and the challenges to obtaining high-performance cost-effective solar cells.

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Science.gov (United States)

Wu, Jiayang; Moein, Tania; Xu, Xingyuan; Moss, David J.

2018-04-01

We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

Corrosion behavior of Haynes {sup registered} 230 {sup registered} nickel-based super-alloys for integrated coal gasification combined cycle syngas plants. A plant exposure study

Energy Technology Data Exchange (ETDEWEB)

Lee, Sungkyu; Lee, Jieun; Kang, Suk-Hwan; Lee, Seung-Jong; Yun, Yongseung [Institute for Advanced Engineering (IAE), Gyeonggi-do (Korea, Republic of). Plant Engineering Center; Kim, Min Jung [Sungkyunkwan Univ, Gyeonggi-do (Korea, Republic of). Advanced Materials Technology Research Center

2015-07-01

The corrosion behavior of commercially available Haynes {sup registered} 230 {sup registered} nickel-based alloy samples was investigated by exposure to coal-gasifying integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160-300 C). The morphological and microstructural analyses of the exposed samples were conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis on the external surface of the recovered corrosion test samples to obtain information of the corrosion scale. These analyses based on the pre- and post-exposure corrosion test samples combined with thermodynamic Ellingham-Pourbaix stability diagrams provided preliminary insight into the mechanism of the observed corrosion behavior prevailing in the piping materials that connected the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material wastage was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested: the observed material waste and corrosion behavior of the Haynes {sup registered} 230 {sup registered} nickel-based alloy samples cut off from the coal syngas integrated coal gasification combined cycle plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered. This contribution continues the already published studies of the Fe-Ni-Cr-Co alloy Haynes {sup registered} 556 {sup registered}.

X-ray diffraction analysis of InAs nanowires

International Nuclear Information System (INIS)

Davydok, Anton

2013-01-01

Semiconductor nanowires have attracted great interest as building blocks for future electronic and optoelectronic devices. The variability of the growth process opens the opportunity to control and combine the various properties tailoring for specific application. It was shown that the electrical and optical characteristics of the nanowires are strongly connected with their structure. Despite intensive research in this field, the growth process is still not fully understood. In particular, extensive real structure investigations are required. Most of the reports dedicated on the structural researches are based on the results of scanning electron microscopy (SEM) or transmission electron microscopy (TEM). SEM provides an image of the surface with nanostructures and is mainly used to describe the morphology of the sample, but it does not bring information about the internal structure, phase composition and defect structure. At the same time, the internal structure can be examined by TEM down to atomic scale. TEM image of good quality are very expensive due to the efforts in sample preparation and in localisation of a single object. All these aspects make the statistical structural analysis difficult. In the present work, X-ray diffraction analysis has been applied for structural investigation of InAs nanowires grown by different techniques. Using various X-ray diffraction geometries, the nanowire systems were investigated in terms of the lattice parameters, phase composition, strains and displacement fields and stacking defects. In particular, realizing grazing incidence diffraction and controlling the penetration depth of X-ray beam, we characterized sample series grown by Au-assisted metal organic phase epitaxy on GaAs [111]B substrate with different growth time. According to the results of SEM and X-ray investigations, a model of the growth process has been proposed. A more detailed analysis was performed on InAs nanowires grown by molecular beam epitaxy (MBE) on

BiOCl nanowire with hierarchical structure and its Raman features

International Nuclear Information System (INIS)

Tian Ye; Guo Chuanfei; Guo Yanjun; Wang Qi; Liu Qian

2012-01-01

BiOCl is a promising V-VI-VII-compound semiconductor with excellent optical and electrical properties, and has great potential applications in photo-catalysis, photoelectric, etc. We successfully synthesize BiOCl nanowire with a hierarchical structure by combining wet etch (top-down) with liquid phase crystal growth (bottom-up) process, opening a novel method to construct ordered bismuth-based nanostructures. The morphology and lattice structures of Bi nanowires, β-Bi 2 O 3 nanowires and BiOCl nanowires with the hierarchical structure are investigated by scanning electron microscope (SEM) and transition electron microscope (TEM). The formation mechanism of such ordered BiOCl hierarchical structure is considered to mainly originate from the highly preferred growth, which is governed by the lattice match between (1 1 0) facet of BiOCl and (2 2 0) or (0 0 2) facet of β-Bi 2 O 3 . A schematic model is also illustrated to depict the formation process of the ordered BiOCl hierarchical structure. In addition, Raman properties of the BiOCl nanowire with the hierarchical structure are investigated deeply.

Long Silver Nanowires Synthesis by Pulsed Electrodeposition

Directory of Open Access Journals (Sweden)

M.R. Batevandi

2015-09-01

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

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

Directory of Open Access Journals (Sweden)

Junhong Zhao

2016-06-01

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

A Yellow Emitting InGaN/GaN Nanowires-based Light Emitting Diode Grown on Scalable Quartz Substrate

KAUST Repository

Prabaswara, Aditya

2017-05-08

The first InGaN/GaN nanowires-based yellow (λ = 590 nm) light-emitting diodes on scalable quartz substrates are demonstrated, by utilizing a thin Ti/TiN interlayer to achieve simultaneous substrate conductivity and transparency.

A Yellow Emitting InGaN/GaN Nanowires-based Light Emitting Diode Grown on Scalable Quartz Substrate

KAUST Repository

Prabaswara, Aditya; Ng, Tien Khee; Zhao, Chao; Janjua, Bilal; Alyamani, Ahmed; El-desouki, Munir; Ooi, Boon S.

2017-01-01

The first InGaN/GaN nanowires-based yellow (λ = 590 nm) light-emitting diodes on scalable quartz substrates are demonstrated, by utilizing a thin Ti/TiN interlayer to achieve simultaneous substrate conductivity and transparency.

Preparation and characterization of CuO nanowire arrays

International Nuclear Information System (INIS)

Yu Dongliang; Ge Chuannan; Du Youwei

2009-01-01

CuO nanowire arrays were prepared by oxidation of copper nanowires embedded in anodic aluminum oxide (AAO) membranes. The AAO was fabricated in an oxalic acid at a constant voltage. Copper nanowires were formed in the nanopores of the AAO membranes in an electrochemical deposition process. The oxidized copper nanowires at different temperatures were studied. X-ray diffraction patterns confirmed the formation of a CuO phase after calcining at 500 0 C in air for 30 h. A transmission electron microscopy was used to characterize the nanowire morphologies. Raman spectra were performed to study the CuO nanowire arrays. After measuring, we found that the current-voltage curve of the CuO nanowires is nonlinear.

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

DEFF Research Database (Denmark)

Pu, Minhao; Hu, Hao; Peucheret, Christophe

2012-01-01

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