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Silicon nanowire

Jin-Sung Park, Kyoung-Ho Kim, Min-Soo Hwang, Xing Zhang, Jung Min Lee, Jungkil Kim, Kyung-Deok Song, You-Shin No, Kwang-Yong Jeong, James F Cahoon, Sun-Kyung Kim, Hong-Gyu Park
We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a Si3N4 grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the Si3N4 gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer...
November 17, 2017: Nano Letters
Alexei Bouravleuv, Igor Ilkiv, Rodion Reznik, Konstantin Kotlyar, Ilya Soshnikov, George Cirlin, Pavel Brunkov, Demid Kirilenko, Leonid V Bondarenko, Aleksandr Nepomnyaschiy, Dimitry V Gruznev, Andrey V Zotov, Alexander Saranin, Veer Dhaka, Harri Lipsanen
We present a new method for the deposition of colloidal Au nanoparticles on the surface of silicon substrates based on short-time Ar plasma treatment without the use of any polymeric layers. The elaborated method is compatible with molecular beam epitaxy, which allowed us to carry out the detailed study of GaAs nanowire synthesis on Si(111) substrates using colloidal Au nanoparticles as seeds for their growth. The results obtained elucidated the causes of the difference between the initial nanoparticle sizes and the diameters of the grown nanowires...
November 14, 2017: Nanotechnology
Jesse W Kremenak, Christopher J Arendse, Franscious R Cummings, Yiyao Chen, Paul F Miceli
Although metal-catalysts are commonly used to create nanoscale materials at surfaces, little is quantitatively known or understood about the depth distribution profile of the catalyst during the growth process. Using X-ray reflectivity, we report the first quantitative investigation, with nanoscale resolution, of the Ag metal-catalyst depth distribution profile during metal-assisted chemical etch (MACE) growth of Si nanowire (SiNW) arrays on Si(100). Given the very low optical reflectivity of these nanowire arrays, specular reflection from these materials in the X-ray region is extremely challenging to measure because it probes interfaces on the nanoscale...
November 9, 2017: Nanoscale
B Ibarlucea, T Rim, C K Baek, J A G M de Visser, L Baraban, G Cuniberti
Miniaturized and cost-efficient methods aiming at high throughput analysis of microbes are of great importance for the surveillance and control of infectious diseases and the related issue of antimicrobial resistance. Here we demonstrate a miniature nanosensor based on a honeycomb-patterned silicon nanowire field effect transistor (FET) capable of detection of bacterial growth and antibiotic response in microbiologically relevant nutrient media. We determine the growth kinetics and metabolic state of Escherichia coli cells in undiluted media via the quantification of changes in the source-drain current caused by varying pH values...
November 9, 2017: Lab on a Chip
Thomas David, Kailang Liu, Antoine Ronda, Luc Favre, Marco Abbarchi, Marc Gailhanou, Pascal Gentile, Denis Buttard, Vincent Calvo, Michele Amato, Jean-Noël Aqua, Isabelle Berbezier
Selective oxidation of the silicon element of silicon germanium (SiGe) alloys during thermal oxidation is a very important and technologically relevant mechanism used to fabricate a variety of microelectronic devices. We develop here a simple integrative approach involving vapor-liquid-solid (VLS) growth followed by selective oxidation steps to the construction of core-shell nanowires and higher-level ordered systems with scalable configurations. We examine the selective oxidation/condensation process under nonequilibrium conditions that gives rise to spontaneous formation of core-shell structures by germanium condensation...
November 14, 2017: Nano Letters
Tanju Yildirim, Kiho Cho, Xiaoyu Wu, Yuerui Lu
Mechanically induced nonlinearities in nano-electromechanical systems (NEMSs) are typically avoided in design due to their unpredictable nature; however, by incorporating these normally unwanted nonlinear and chaotic phenomena, the performance of NEMS devices displays substantially different characteristics opening a broad new range of potential applications for their use. In this work, experiments have been conducted for probing the chaotic boundary of a circular membrane mechanical resonator with and without a silicone nanowire array (Si NWA)...
November 16, 2017: Nanoscale
Zhenhai Yang, Zhaolang Liu, Jiang Sheng, Wei Guo, Yuheng Zeng, Pingqi Gao, Jichun Ye
Recently, silicon single nanowire solar cells (SNSCs) serving as the sustainable self-power sources have been integrated into optoelectronic nanodevices under the driver of technology and economy. However, conventional SNSC cannot provide the minimum energy consumption for the operation of nanodevices due to its low power conversion efficiency (PCE). Here, we propose an innovative approach to combine the n-type silicon nanowires (SiNWs) with p-type poly(3,4-ethylthiophene):poly(styrenesulfonate) (PEDOT:PSS) to form the p (+) n heterojunction, which shows superior opto-electric performances...
November 6, 2017: Scientific Reports
Xiang Zhang, Bryn Bell, Mark Pelusi, Jiakun He, Wei Geng, Yunchuan Kong, Philipp Zhang, Chunle Xiong, Benjamin J Eggleton
Integrated single-photon sources are a key component for photonic quantum technology but are generally limited to low single-photon rates. For sources based on photon pair generation by four-wave mixing, increasing the repetition rate of pump laser pulses is a straightforward way to enhance the single-photon rate, but the benefits and practical limitations have not yet been demonstrated and analyzed in a CMOS-compatible platform. In this work, we demonstrate correlated photon pair generation in integrated silicon nanowires and systematically analyze the count rate and coincidence to accidental ratio as the pump rate is varied between 156...
October 20, 2017: Applied Optics
Jung-Taek Lim, Yo-Seop Yoon, Won-Yong Lee, Jin-Tak Jeong, Gil-Sung Kim, Tae Geun Kim, Sang-Kwon Lee
Nanostructured materials, such as silicon nanowires, quartz nanostructures, and polymer-modified nanostructures, are a promising new class of materials for the capture and enumeration of very rare tumor cells, including circulating tumor cells (CTCs), to examine their biological characteristics in whole blood of cancer patients. These cells can then be used for transplantation, anti-tumor cell therapy, and cell-secreted protein studies. It is believed that 3-dimensional (3D) nanostructured substrates efficiently enhance cell capture yields due to the increased local contacts between the 3D nanostructures and extracellular extensions of the tumor cells...
November 16, 2017: Nanoscale
C J Delker, J Y Yoo, E Bussmann, B S Swartzentruber, C T Harris
We investigate carrier transport in silicon-germanium nanowires with an axial p-n junction doping profile by fabricating these wires into transistors that feature separate top gates over each doping segment. By independently biasing each gate, carrier concentrations in the n- and p-side of the wire can be modulated. For these devices, which were fabricated with nickel source-drain electrical contacts, holes are the dominant charge carrier, with more favorable hole injection occurring on the p-side contact. Channel current exhibits greater sensitivity to the n-side gate, and in the reverse biased source-drain configuration, current is limited by the nickel/n-side Schottky contact...
October 23, 2017: Nanotechnology
Chalermchai Himwas, Stéphane Collin, Pierre Rale, Nicolas Chauvin, Gilles Patriarche, Fabrice Oehler, François Julien, Laurant Travers, Jean-Christophe Harmand, Maria Tchenycheva
We report on the structural and optical properties of GaAsP nanowires (NWs) grown by molecular-beam epitaxy. By adjusting the alloy composition in the NWs, the transition energy was tuned to the optimal value required for tandem III-V/silicon solar cells. We discovered that an unintentional shell was also formed during the GaAsP NW growth. The NW surface was passivated by an in-situ deposition of a radial Ga(As)P shell. Different shell compositions and thicknesses were investigated. We demonstrate that the optimal passivation conditions for GaAsP NWs (with a gap of 1...
October 23, 2017: Nanotechnology
M Salvato, R Baghdadi, C Cirillo, S L Prischepa, A L Dolgiy, V P Bondarenko, F Lombardi, C Attanasio
Superconducting NbN nanonetworks with a very small number of interconnected nanowires, with diameter of the order of 4 nm, are fabricated combining a bottom-up (use of porous silicon nanotemplates) with a top-down technique (high-resolution electron beam lithography). The method is easy to control and allows the fabrication of devices, on a robust support, with electrical properties close to a one-dimensional superconductor that can be used fruitfully for novel applications.
October 20, 2017: Nanotechnology
Yang Chen, Oliver Höhn, Nico Tucher, Mats-Erik Pistol, Nicklas Anttu
A tandem solar cell consisting of a III-V nanowire subcell on top of a planar Si subcell is a promising candidate for next generation photovoltaics due to the potential for high efficiency. However, for success with such applications, the geometry of the system must be optimized for absorption of sunlight. Here, we consider this absorption through optics modeling. Similarly, as for a bulk dual-junction tandem system on a silicon bottom cell, a bandgap of approximately 1.7 eV is optimum for the nanowire top cell...
August 7, 2017: Optics Express
Luye Mu, Ilia A Droujinine, Jieun Lee, Mathias Wipf, Paschall Davis, Chris Adams, Jennifer Hannant, Mark A Reed
Silicon nanowire field effect transistors (NWFETs) are low noise, low power, ultrasensitive biosensors that are highly amenable to integration. However, using NWFETs to achieve direct protein detection in physiological buffers such as blood serum remains difficult due to Debye screening, nonspecific binding, and stringent functionalization requirements. In this work, we performed an indirect sandwich immunoassay in serum combined with exponential DNA amplification and pH measurement by ultrasensitive NWFET sensors...
November 7, 2017: Analytical Chemistry
Francisco de Santiago, Alejandro Trejo, Alvaro Miranda, Eliel Carvajal, Luis Antonio Pérez, Miguel Cruz-Irisson
In this work, we address the effects of molecular doping on the electronic properties of fluorinated and chlorinated silicon nanowires (SiNWs), in comparison with those corresponding to hydrogen-passivated SiNWs. Adsorption of n-type dopant molecules on hydrogenated and halogenated SiNWs and their chemisorption energies, formation energies, and electronic band gap are studied by using density functional theory calculations. The results show that there are considerable charge transfers and strong covalent interactions between the dopant molecules and the SiNWs...
October 16, 2017: Journal of Molecular Modeling
Yunfei Ge, Yuan Zhang, Jonathan Weaver, Phillip Dobson
Scanning Thermal Microscopy (SThM) is a technique which is often used for the measurement of the thermal conductivity of materials at the nanometre scale. The impact of nano-scale feature size and shape on apparent thermal conductivity, as measured using scanning thermal microscopy, has been investigated. To achieve this, our recently developed topography-free samples with 200 nm and 400 nm wide gold wires (50 nm thick) of length of 400 - 2500 nm were fabricated and their thermal resistance measured and analyzed...
October 16, 2017: Nanotechnology
Earl T Ritchie, David J Hill, Tucker M Mastin, Panfilo C Deguzman, James F Cahoon, Joanna M Atkin
We report the use of infrared (IR) scattering-type scanning near-field optical microscopy (s-SNOM) as a nondestructive method to map free-carriers in axially modulation-doped silicon nanowires (SiNWs) with nanoscale spatial resolution. Using this technique, we can detect local changes in the electrically active doping concentration based on the infrared free-carrier response in SiNWs grown using the vapor-liquid-solid (VLS) method. We demonstrate that IR s-SNOM is sensitive to both p-type and n-type free-carriers for carrier densities above ∼1 × 10(19) cm(-3)...
October 30, 2017: Nano Letters
Zahid Ali Khan Durrani, Mervyn E Jones, Chen Wang, Marijke Scotuzzi, Cornelis W Kees Hagen
Nanostructures of platinum-carbon nanocomposite material have been formed by electron-beam induced deposition (EBID). These consist of nanodots and nanowires with a minimum size ~20 nm, integrated within ~100 nm nanogap n-type silicon-on-insulator transistor structures. The nanodot transistors use ~20 nm Pt/C nanodots, tunnel-coupled to Pt/C nanowire electrodes, bridging the Si nanogaps. Room-temperature single-electron transistor operation has been measured, and single-electron current oscillations and 'Coulomb diamonds' observed...
October 13, 2017: Nanotechnology
Marcus Schmerling, Daniela Fenske, Fabian Peters, Julian Schwenzel, Matthias Busse
Metal-assisted chemical etching (MACE) provides a versatile way to synthesize silicon nanowires of different morphologies. We used MACE to synthesize oxide-free porous and nonporous SiNW for the use in anodes for lithium-ion batteries. To improve their processing behavior the SiNW were functionalized using acrylic acid. Differential capacity plots were used as a way to identify the degradation processes during cycling through tracking the occurrence of Li15Si4 and changes in polarization. The cycling performance between porous and nonporous SiNW differed regarding coulombic efficiency and cycling stability...
October 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ying Liu, Ali Rahimian, Sergiy Krylyuk, Tam Vu, Bruno Crulhas, Gulnaz Stybayeva, Meruyert Imanbekova, Dong-Sik Shin, Albert Davydov, Alexander Revzin
Cytokines are small proteins secreted by immune cells in response to pathogens/infections; therefore, these proteins can be used in diagnosing infectious diseases. For example, release of a cytokine interferon (IFN)-γ from T-cells is used for blood-based diagnosis of tuberculosis (TB). Our lab has previously developed an atpamer-based electrochemical biosensor for rapid and sensitive detection of IFN-γ. In this study, we explored the use of silicon nanowires (NWs) as a way to create nanostructured electrodes with enhanced sensitivity for IFN-γ...
October 9, 2017: ACS Sensors
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