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Silicon nanowire

Risheng Cheng, Xiang Guo, Xiaosong Ma, Linran Fan, King Y Fong, Menno Poot, Hong X Tang
We describe a micromachining process to allow back-side coupling of an array of single-mode telecommunication fibers to individual superconducting nanowire single photon detectors (SNSPDs). This approach enables a back-illuminated detector structure which separates the optical access and electrical readout on two sides of the chip and thus allows for compact integration of multi-channel detectors. As proof of principle, we show the integration of four detectors on the same silicon chip with two different designs and their performances are compared...
November 28, 2016: Optics Express
Ramesh Ghosh, P K Giri
Semiconductor nanowires (NWs), in particular Si NWs, have attracted much attention in the last decade for their unique electronic properties and potential applications in several emerging areas. With the introduction of heterostructures (HSs) on NWs, new functionalities are obtained and the device performance is improved significantly in many cases. Due to the easy fabrication techniques, excellent optoelectronic properties and compatibility of forming HSs with different inorganic/organic materials, Si NW HSs have been utilized in various configurations and device architectures...
November 28, 2016: Nanotechnology
Tong Jin, Da He, Wei Li, Charles J Stanton, Sebastian A Pantovich, George F Majetich, Henry F Schaefer, Jay Agarwal, Dunwei Wang, Gonghu Li
The CO2-reduction activity of two Re(i)-NHC complexes is investigated employing a silicon nanowire photoelectrode to drive catalysis. Photovoltages greater than 440 mV are observed along with excellent selectivity towards CO over H2 formation. The observed selectivity towards CO production correlates with strong adsorption of the catalysts on the photoelectrode surface.
November 22, 2016: Chemical Communications: Chem Comm
M Agati, G Amiard, V Le Borgne, P Castrucci, R Dolbec, M De Crescenzi, M A El Khakani, S Boninelli
Ultra-thin Silicon Nanowires (SiNWs) were produced by means of an industrial inductively-coupled plasma (ICP) based process. Two families of SiNWs have been identified, namely long SiNWs (up to 2-3 micron in length) and shorter ones (~100 nm). SiNWs were found to consist of a Si core (with diameter as thin as 2 nm) and a silica shell, of which the thickness varies from 5 to 20 nm. By combining advanced transmission electron microscopy (TEM) techniques, we demonstrate that the growth of the long SiNWs occurred via the Oxide Assisted Growth (OAG) mechanism, while the Vapor Liquid Solid (VLS) mechanism is responsible for the growth of shorter ones...
November 22, 2016: Scientific Reports
Jeonghoon Yun, Jae-Hyuk Ahn, Bong Jae Lee, Dong-Il Moon, Yang-Kyu Choi, Inkyu Park
We developed a novel method to measure local temperature at micro/nano-scale regions using selective deposition of quantum dots (QDs) as a sensitive temperature probe and measured the temperature of Joule heated silicon microwires (SiMWs) and silicon nanowires (SiNWs) by this method. The QDs are selectively coated only on the surface of the SiMWs and SiNWs by a sequential process composed of selective opening of a polymethyl methacrylate layer via Joule heating, covalent bonding of QDs, and lift-off process...
December 16, 2016: Nanotechnology
Sylvain Sergent, Masato Takiguchi, Hideaki Taniyama, Akihiko Shinya, Eiichi Kuramochi, Masaya Notomi
Nanowire-induced SiN photonic crystal (PhC) nanocavities specifically designed for the ultra-violet and visible range are investigated by three-dimensional finite-difference time-domain calculations. As opposed to their silicon PhC counterpart, we find that the formation of nanowire-induced two-dimensional (2D) SiN PhC nanocavities is more challenging because of the low refractive index of SiN. We thus discuss optimization strategies to circumvent such difficulties and we investigate the influence of critical design parameters such as PhC geometry, as well as nanowire geometry and position...
November 14, 2016: Optics Express
Navneet Dhindsa, Jaspreet Walia, Simarjeet Singh Saini
We demonstrate submicron thick platform integrating amorphous silicon nanowires and thin-films achieving vivid colors in transmission and reflection. The platform nearly doubles the absorption efficiency compared to the starting thin-film without much compromising with color diverseness. The structural colors can be changed over a wide range by changing the diameters of the nanowires while still keeping the absorption efficiency higher than starting thin-film. The optical response of the platform is conceptually understood for different diameters combined with different thin-film thicknesses indicating the presence of leaky waveguide modes and coupled cavity modes...
December 9, 2016: Nanotechnology
Zhihao Jia, Qiang Cheng, Jinlin Song, Yifan Zhou, Yang Liu
This paper proposes an assembly structure incorporating two-dimensional silicon gratings and germanium nanorods applied to photovoltaic absorbers. The absorptance of the assembly structure is numerically investigated using the finite-difference time-domain method. The results demonstrate that such a structure can greatly improve the absorptance and conversion efficiency compared to the gratings or nanowires in the 300-1100 nm wavelength region. The average spectral absorptance of such a structure reaches up to 0...
November 1, 2016: Applied Optics
Siti Noorhaniah Yusoh, Khatijah Aisha Yaacob
The optimization of etchant parameters in wet etching plays an important role in the fabrication of semiconductor devices. Wet etching of tetramethylammonium hydroxide (TMAH)/isopropyl alcohol (IPA) on silicon nanowires fabricated by AFM lithography is studied herein. TMAH (25 wt %) with different IPA concentrations (0, 10, 20, and 30 vol %) and etching time durations (30, 40, and 50 s) were investigated. The relationships between etching depth and width, and etching rate and surface roughness of silicon nanowires were characterized in detail using atomic force microscopy (AFM)...
2016: Beilstein Journal of Nanotechnology
Wei Zhou, Xiaochuan Dai, Charles M Lieber
Semiconductor nanowires represent powerful building blocks for next generation bioelectronics given their attractive properties, including nanometer-scale footprint comparable to subcellular structures and bio-molecules, configurable in nonstandard device geometries readily interfaced with biological systems, high surface-to-volume ratios, fast signal responses, and minimum consumption of energy. In this review article, we summarize recent progress in the field of nanowire bioelectronics with a focus primarily on silicon nanowire field-effect transistor biosensors...
November 8, 2016: Reports on Progress in Physics
Hyun Jung, Byung Chul Yeo, Kwang-Ryeol Lee, Sang Soo Han
Although silicon oxide (SiOx) nanowires (NWs) are recognized as a promising anode material for lithium-ion batteries (LIBs), a clear understanding of their lithiation mechanism has not been reported yet. We elucidate the lithiation mechanism of SiOx NWs at the atomic scale based on molecular dynamics (MD) simulations employing the ReaxFF reactive force field developed through first-principles calculations. SiOx NWs with crystalline Si (c-Si) core and amorphous SiO2 (a-SiO2) shell structures of ∼1 nm in thickness show smaller volume expansion than pristine Si NWs, as found in previous experiments...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
Hairui Ren, Zhaoyang Chen, Xin Zhang, Yongmei Zhao, Zheng Wang, Zhenglong Wu, Haijun Xu
Concentrations of S-Adenosyl-L-Methionine (SAM) in aqueous solution and fermentation liquids were quantitatively determined by surface-enhanced Raman scattering (SERS) and verified by high-pressure liquid chromatography (HPLC). The Ag nanoparticle/silicon nanowire array substrate was fabricated and employed as an active SERS substrate to indirectly measure the SAM concentration. The linear relationship between the integrated intensity of peak centered at ~2920 cm(-1) in SERS spectra and the SAM concentration was established, and the limit of detections of SAM concentrations was analyzed to be ~0...
2016: Journal of Analytical Methods in Chemistry
Pablo Cencillo-Abad, Jun-Yu Ou, Eric Plum, João Valente, Nikolay I Zheludev
While metamaterials offer engineered static optical properties, future artificial media with dynamic random-access control over shape and position of meta-molecules will provide arbitrary control of light propagation. The simplest example of such a reconfigurable metamaterial is a nanowire grid metasurface with subwavelength wire spacing. Recently we demonstrated computationally that such a metadevice with individually controlled wire positions could be used as dynamic diffraction grating, beam steering module and tunable focusing element...
December 2, 2016: Nanotechnology
Woongsik Nam, James I Mitchell, Xianfan Xu
We demonstrate a single-step, laser-based technique to fabricate axial modulation-doped silicon nanowires. Our method is based on laser-direct-write chemical vapor deposition and has the capability to fabricate nanowires as small as 60 nm, which is far below the diffraction limit of the laser wavelength of 395 nm, with precise control of nanowire position, length, and orientation. By switching dopant gases during nanowire writing, p-n junction nanowires are produced. The p-n junction nanowires are fabricated into multifinger devices with parallel metal contacts and electrically tested to demonstrate diode characteristics...
December 2, 2016: Nanotechnology
Xiaolei Wang, Ge Li, Min Ho Seo, Gregory Lui, Fathy M Hassan, Kun Feng, Xingcheng Xiao, Zhongwei W Chen
A novel self-supported electrode with long cycling life and high mass loading is developed based on carbon-coated Si nanowires in situ grown on highly conductive and flexible carbon fabric substrates through a nickel catalyzed one-pot atmospheric pressure chemical vapor deposition. The high-quality carbon coated Si nanowires result in high reversible specific capacity (~3500 mA h g(-1) at 100 mA g(-1)), while 3D electrode's unique architecture leads to a significantly improved robustness and a high degree of electrode stability...
November 3, 2016: ACS Applied Materials & Interfaces
Andrew C Meng, Colleen Shang Fenrich, Michael R Braun, James P McVittie, Ann F Marshall, James S Harris, Paul C McIntyre
Germanium-tin alloy nanowires hold promise as silicon-compatible optoelectronic elements with the potential for achieving a direct band gap transition required for efficient light emission. In contrast to Ge1-xSnx epitaxial thin films, free-standing nanowires deposited on misfitting germanium or silicon substrates can avoid compressive elastic strains that inhibit formation of a direct gap. We demonstrate strong room temperature photoluminescence, consistent with band edge emission from both the Ge core nanowires, elastically strained in tension, and the almost unstrained Ge1-xSnx shells grown around them...
November 1, 2016: Nano Letters
Jinyong Choi, Youngin Jeon, Kyoungah Cho, Sangsig Kim
In this study, we demonstrate the substantial enhancement of the thermoelectric power factors of silicon nanowires (SiNWs) on plastic substrates achievable by field-effect modulation. The Seebeck coefficient and electrical conductivity are adjusted by varying the charge carrier concentration via electrical modulation with a gate voltage in the 0 to ±5 range, thus enhancing the power factors from 2.08 to 935 μW K(-2) m(-1)) for n-type SiNWs, and from 453 to 944 μW K(-2) m(-1)) for p-type SiNWs. The electrically modulated thermoelectric characteristics of SiNWs are analyzed and discussed...
October 31, 2016: Nanotechnology
Xin Zhao, M H Alizadeh, Björn M Reinhard
Hybrid structures containing plasmonic and photonic components can enhance light-matter interaction through both photonic and plasmonic modes and potentially their interactions. In this article, we systematically investigate the optical properties of nanoparticle-tipped silicon nanowires (NPTWs) and characterize their ability to enhance the fluorescence signal of two cyanine dyes (Cy3 and Cy5) selectively bound to the gold tip. Although both gold and silicon components contribute to the fluorescence signal enhancement, the experimentally observed strong morphology dependence of the fluorescence emission enhancement is demonstrated to depend on tunable leaky modes of the silicon nanowires...
September 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Yimin Yao, Xiaoliang Zeng, Guiran Pan, Jiajia Sun, Jiantao Hu, Yun Huang, Rong Sun, Jian-Bin Xu, Ching-Ping Wong
Polymer composites with high thermal conductivity have attracted much attention, along with the rapid development of electronic devices toward higher speed and better performance. However, high interfacial thermal resistance between fillers and matrix or between fillers and fillers has been one of the primary bottlenecks for the effective thermal conduction in polymer composites. Herein, we report on engineering interfacial structure of silicon carbide nanowire/cellulose microcrystal paper by generating silver nanostructures...
October 27, 2016: ACS Applied Materials & Interfaces
Shan Jiang, Choon Peng Teng
Microbial contamination on various surfaces is one of the greatest health problems worldwide, afflicting millions of peoples annually. Given the advantages of silver nanowires (AgNWs) in forming a percolated network when fabricated into a film, there is significant interest in developing AgNWs loaded polymeric coatings for antimicrobial applications. In this work, AgNWs with high aspect ratio are drop-coated onto a silicon wafer to form a uniform interconnected network. The AgNW network is then embedded into polydimethylsiloxane (PDMS) matrix to fabricate AgNWs/PDMS film...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
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