Flexible integration of free-standing nanowires into silicon photonics.

Science.gov (United States)

Chen, Bigeng; Wu, Hao; Xin, Chenguang; Dai, Daoxin; Tong, Limin

2017-06-14

Silicon photonics has been developed successfully with a top-down fabrication technique to enable large-scale photonic integrated circuits with high reproducibility, but is limited intrinsically by the material capability for active or nonlinear applications. On the other hand, free-standing nanowires synthesized via a bottom-up growth present great material diversity and structural uniformity, but precisely assembling free-standing nanowires for on-demand photonic functionality remains a great challenge. Here we report hybrid integration of free-standing nanowires into silicon photonics with high flexibility by coupling free-standing nanowires onto target silicon waveguides that are simultaneously used for precise positioning. Coupling efficiency between a free-standing nanowire and a silicon waveguide is up to ~97% in the telecommunication band. A hybrid nonlinear-free-standing nanowires-silicon waveguides Mach-Zehnder interferometer and a racetrack resonator for significantly enhanced optical modulation are experimentally demonstrated, as well as hybrid active-free-standing nanowires-silicon waveguides circuits for light generation. These results suggest an alternative approach to flexible multifunctional on-chip nanophotonic devices.Precisely assembling free-standing nanowires for on-demand photonic functionality remains a challenge. Here, Chen et al. integrate free-standing nanowires into silicon waveguides and show all-optical modulation and light generation on silicon photonic chips.

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

International Nuclear Information System (INIS)

Pham, Van Binh; Tung Pham, Xuan Thanh; Duong Dang, Ngoc Thuy; Tuyen Le, Thi Thanh; Tran, Phu Duy; Nguyen, Thanh Chien; Nguyen, Van Quoc; Dang, Mau Chien; Tong, Duy Hien; Van Rijn, Cees J M

2011-01-01

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

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.

Effect of Silicon Nanowire on Crystalline Silicon Solar Cell Characteristics

OpenAIRE

Zahra Ostadmahmoodi Do; Tahereh Fanaei Sheikholeslami; Hassan Azarkish

2016-01-01

Nanowires (NWs) are recently used in several sensor or actuator devices to improve their ordered characteristics. Silicon nanowire (Si NW) is one of the most attractive one-dimensional nanostructures semiconductors because of its unique electrical and optical properties. In this paper, silicon nanowire (Si NW), is synthesized and characterized for application in photovoltaic device. Si NWs are prepared using wet chemical etching method which is commonly used as a simple and low cost method fo...

Silicon nanowires: structure and properties

International Nuclear Information System (INIS)

Nezhdanov, A.V.; Mashin, A.I.; Razuvaev, A.G.; Ershov, A.V.; Ignatov, S.K.

2006-01-01

An attempt to grow silicon nanowires has been made by electron beam evaporation on highly oriented pyrolytic substrate. Needle-like objects are located along the normal to a substrate (density 2 x 10 11 cm -2 ). For modeling quasi-one-dimensional objects calculations of nuclear structure and energy spectra have been accomplished. A fullerene-like structure Si 24 is proposed as a basic atomic configuration of silicon nanowires [ru

Position-controlled epitaxial III-V nanowires on silicon

Energy Technology Data Exchange (ETDEWEB)

Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M [Philips Research Laboratories, Professor Holstlaan 4, 5656 AA Eindhoven (Netherlands); Kavli Institute of NanoScience, Delft University of Technology, PO Box 5046, 2600 GA Delft (Netherlands)

2006-06-14

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires.

Position-controlled epitaxial III-V nanowires on silicon

International Nuclear Information System (INIS)

Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires

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)

Tracing the pH dependent activation of autophagy in cancer cells by silicon nanowire-based impedance biosensor.

Science.gov (United States)

Alikhani, Alireza; Gharooni, Milad; Abiri, Hamed; Farokhmanesh, Fatemeh; Abdolahad, Mohammad

2018-05-30

Monitoring the pH dependent behavior of normal and cancer cells by impedimetric biosensor based on Silicon Nanowires (SiNWs) was introduced to diagnose the invasive cancer cells. Autophagy as a biologically activated process in invasive cancer cells during acidosis, protect them from apoptosis in lower pH which presented in our work. As the autophagy is the only activated pathways which can maintain cellular proliferation in acidic media, responses of SiNW-ECIS in acidified cells could be correlated to the probability of autophagy activation in normal or cancer cells. In contrast, cell survival pathway wasn't activated in low-grade cancer cells which resulted in their acidosis. The measured electrical resistance of MCF10, MCF7, and MDA-MB468 cell lines, by SiNW sensor, in normal and acidic media were matched by the biological analyses of their vital functions. Invasive cancer cells exhibited increased electrical resistance in pH 6.5 meanwhile the two other types of the breast cells exhibited sharp (MCF10) and moderate (MCF7) decrease in their resistance. This procedure would be a new trend in microenvironment based cancer investigation. Copyright © 2018 Elsevier B.V. All rights reserved.

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.)

Self-diffusion in single crystalline silicon nanowires

Science.gov (United States)

Südkamp, T.; Hamdana, G.; Descoins, M.; Mangelinck, D.; Wasisto, H. S.; Peiner, E.; Bracht, H.

2018-04-01

Self-diffusion experiments in single crystalline isotopically controlled silicon nanowires with diameters of 70 and 400 nm at 850 and 1000 °C are reported. The isotope structures were first epitaxially grown on top of silicon substrate wafers. Nanowires were subsequently fabricated using a nanosphere lithography process in combination with inductively coupled plasma dry reactive ion etching. Three-dimensional profiling of the nanosized structure before and after diffusion annealing was performed by means of atom probe tomography (APT). Self-diffusion profiles obtained from APT analyses are accurately described by Fick's law for self-diffusion. Data obtained for silicon self-diffusion in nanowires are equal to the results reported for bulk silicon crystals, i.e., finite size effects and high surface-to-volume ratios do not significantly affect silicon self-diffusion. This shows that the properties of native point defects determined from self-diffusion in bulk crystals also hold for nanosized silicon structures with diameters down to 70 nm.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Silicon Nanowires for All-Optical Signal Processing in Optical Communication

DEFF Research Database (Denmark)

Pu, Minhao; Hu, Hao; Ji, Hua

2012-01-01

Silicon (Si), the second most abundant element on earth, has dominated in microelectronics for many decades. It can also be used for photonic devices due to its transparency in the range of optical telecom wavelengths which will enable a platform for a monolithic integration of optics...... and microelectronics. Silicon photonic nanowire waveguides fabricated on silicon-on-insulator (SOI) substrates are crucial elements in nano-photonic integrated circuits. The strong light confinement in nanowires induced by high index contrast SOI material enhances the nonlinear effects in the silicon nanowire core...... such as four-wave mixing (FWM) which is an imperative process for optical signal processing. Since the current mature silicon fabrication technology enables a precise dimension control on nanowires, dispersion engineering can be performed by tailoring nanowire dimensions to realize an efficient nonlinear...

Piezoresistive effect in top-down fabricated silicon nanowires

DEFF Research Database (Denmark)

Reck, Kasper; Richter, Jacob; Hansen, Ole

2008-01-01

We have designed and fabricated silicon test chips to investigate the piezoresistive properties of both crystalline and polycrystalline nanowires using a top-down approach, in order to comply with conventional fabrication techniques. The test chip consists of 5 silicon nanowires and a reference...

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.)

A Review on the Electrochemical Sensors and Biosensors Composed of Nanowires as Sensing Material

Directory of Open Access Journals (Sweden)

Shen-Ming Chen

2008-01-01

Full Text Available The development and application of nanowires for electrochemical sensors and biosensors are reviewed in this article. Next generation sensor platforms will require significant improvements in sensitivity, specificity and parallelism in order to meet the future needs in variety of fields. Sensors made of nanowires exploit some fundamental nanoscopic effect in order to meet these requirements. Nanowires are new materials, which have the characteristic of low weight with extraordinary mechanical, electrical, thermal and multifunctional properties. The advantages such as size scale, aspect ratio and other properties of nanowires are especially apparent in the use of electrical sensors such as electrochemical sensors and in the use of field-effect transistors. The preparation methods of nanowires and their properties are discussed along with their advantages towards electrochemical sensors and biosensors. Some key results from each article are summarized, relating the concept and mechanism behind each sensor, with experimental conditions as well as their behavior at different conditions.

Superconductive silicon nanowires using gallium beam lithography.

Energy Technology Data Exchange (ETDEWEB)

Henry, Michael David; Jarecki, Robert Leo,

2014-01-01

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

Silicon nanowire transistors

CERN Document Server

Bindal, Ahmet

2016-01-01

This book describes the n and p-channel Silicon Nanowire Transistor (SNT) designs with single and dual-work functions, emphasizing low static and dynamic power consumption. The authors describe a process flow for fabrication and generate SPICE models for building various digital and analog circuits. These include an SRAM, a baseband spread spectrum transmitter, a neuron cell and a Field Programmable Gate Array (FPGA) platform in the digital domain, as well as high bandwidth single-stage and operational amplifiers, RF communication circuits in the analog domain, in order to show this technology’s true potential for the next generation VLSI. Describes Silicon Nanowire (SNW) Transistors, as vertically constructed MOS n and p-channel transistors, with low static and dynamic power consumption and small layout footprint; Targets System-on-Chip (SoC) design, supporting very high transistor count (ULSI), minimal power consumption requiring inexpensive substrates for packaging; Enables fabrication of different types...

Enhanced sensing of dengue virus DNA detection using O_2 plasma treated-silicon nanowire based electrical biosensor

International Nuclear Information System (INIS)

Rahman, S.F.A.; Yusof, N.A.; Hashim, U.; Hushiarian, R.; Nuzaihan, M.N.M.; Hamidon, M.N.; Zawawi, R.M.; Fathil, M.F.M.

2016-01-01

Dengue Virus (DENV) has become one of the most serious arthropod-borne viral diseases, causing death globally. The existing methods for DENV detection suffer from the late stage treatment due to antibodies-based detection which is feasible only after five days following the onset of the illness. Here, we demonstrated the highly effective molecular electronic based detection utilizing silicon nanowire (SiNW) integrated with standard complementary metal-oxide-semiconductor (CMOS) process as a sensing device for detecting deoxyribonucleic acid (DNA) related to DENV in an early stage diagnosis. To transform the fabricated devices as a functional sensing element, three-step procedure consist of SiNW surface modification, DNA immobilization and DNA hybridization were employed. The detection principle works by detecting the changes in current of SiNW which bridge the source and drain terminal to sense the immobilization of probe DNA and their hybridization with target DNA. The oxygen (O_2) plasma was proposed as an effective strategy for increasing the binding amounts of target DNA by modified the SiNW surface. It was found that the detection limit of the optimized O_2 plasma treated-SiNW device could be reduced to 1.985 × 10"−"1"4 M with a linear detection range of the sequence-specific DNA from 1.0 × 10"−"9 M to 1.0 × 10"−"1"3 M. In addition, the developed biosensor device was able to discriminate between complementary, single mismatch and non-complementary DNA sequences. This highly sensitive assay was then applied to the detection of reverse transcription-polymerase chain reaction (RT-PCR) product of DENV-DNA, making it as a potential method for disease diagnosis through electrical biosensor. - Highlights: • Molecular electronic detection of Dengue Virus (DENV) DNA using SiNW biosensor is presented. • Oxygen plasma surface treatment as an enhancer technique for device sensitivity is highlighted. • The limit of detection (LoD) as low as 1.985�

Position-controlled epitaxial III-V nanowires on silicon

NARCIS (Netherlands)

Roest, A.L.; Verheijen, M.A.; Wunnicke, O.; Serafin, S.N.; Wondergem, H.J.; Bakkers, E.P.A.M.

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction

Solution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes

KAUST Repository

Chan, Candace K.; Patel, Reken N.; O’ Connell, Michael J.; Korgel, Brian A.; Cui, Yi

2010-01-01

Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires

Silicon nanowire field-effect transistors for the detection of proteins

Science.gov (United States)

Madler, Carsten

to implantable biosensors wirelessly, eliminating the need for batteries. A metamaterial split ring resonator is integrated with a rectifying circuit for efficient conversion of microwave radiation to direct electrical power. We studied the near-field behavior of this rectenna with respect to distance, polarization, power, and frequency. Using a 100 mW microwave power source, we demonstrated operating a simple silicon nanowire pH sensor with light indicator.

Protein Biosensors Based on Polymer Nanowires, Carbon Nanotubes and Zinc Oxide Nanorods

Directory of Open Access Journals (Sweden)

Taeksoo Ji

2011-05-01

Full Text Available The development of biosensors using electrochemical methods is a promising application in the field of biotechnology. High sensitivity sensors for the bio-detection of proteins have been developed using several kinds of nanomaterials. The performance of the sensors depends on the type of nanostructures with which the biomaterials interact. One dimensional (1-D structures such as nanowires, nanotubes and nanorods are proven to have high potential for bio-applications. In this paper we review these three different kinds of nanostructures that have attracted much attention at recent times with their great performance as biosensors. Materials such as polymers, carbon and zinc oxide have been widely used for the fabrication of nanostructures because of their enhanced performance in terms of sensitivity, biocompatibility, and ease of preparation. Thus we consider polymer nanowires, carbon nanotubes and zinc oxide nanorods for discussion in this paper. We consider three stages in the development of biosensors: (a fabrication of biomaterials into nanostructures, (b alignment of the nanostructures and (c immobilization of proteins. Two different methods by which the biosensors can be developed at each stage for all the three nanostructures are examined. Finally, we conclude by mentioning some of the major challenges faced by many researchers who seek to fabricate biosensors for real time applications.

Facile fabrication of a silicon nanowire sensor by two size reduction steps for detection of alpha-fetoprotein biomarker of liver cancer

International Nuclear Information System (INIS)

Pham, Van Binh; Pham, Xuan ThanhTung; Phan, Thanh Nhat Khoa; Le, Thi Thanh Tuyen; Dang, Mau Chien

2015-01-01

We present a facile technique that only uses conventional micro-techniques and two size-reduction steps to fabricate wafer-scale silicon nanowire (SiNW) with widths of 200 nm. Initially, conventional lithography was used to pattern SiNW with 2 μm width. Then the nanowire width was decreased to 200 nm by two size-reduction steps with isotropic wet etching. The fabricated SiNW was further investigated when used with nanowire field-effect sensors. The electrical characteristics of the fabricated SiNW devices were characterized and pH sensitivity was investigated. Then a simple and effective surface modification process was carried out to modify SiNW for subsequent binding of a desired receptor. The complete SiNW-based biosensor was then used to detect alpha-fetoprotein (AFP), one of the medically approved biomarkers for liver cancer diagnosis. Electrical measurements showed that the developed SiNW biosensor could detect AFP with concentrations of about 100 ng mL"−"1. This concentration is lower than the necessary AFP concentration for liver cancer diagnosis. (paper)

Facile fabrication of a silicon nanowire sensor by two size reduction steps for detection of alpha-fetoprotein biomarker of liver cancer

Science.gov (United States)

Binh Pham, Van; ThanhTung Pham, Xuan; Nhat Khoa Phan, Thanh; Thanh Tuyen Le, Thi; Chien Dang, Mau

2015-12-01

We present a facile technique that only uses conventional micro-techniques and two size-reduction steps to fabricate wafer-scale silicon nanowire (SiNW) with widths of 200 nm. Initially, conventional lithography was used to pattern SiNW with 2 μm width. Then the nanowire width was decreased to 200 nm by two size-reduction steps with isotropic wet etching. The fabricated SiNW was further investigated when used with nanowire field-effect sensors. The electrical characteristics of the fabricated SiNW devices were characterized and pH sensitivity was investigated. Then a simple and effective surface modification process was carried out to modify SiNW for subsequent binding of a desired receptor. The complete SiNW-based biosensor was then used to detect alpha-fetoprotein (AFP), one of the medically approved biomarkers for liver cancer diagnosis. Electrical measurements showed that the developed SiNW biosensor could detect AFP with concentrations of about 100 ng mL-1. This concentration is lower than the necessary AFP concentration for liver cancer diagnosis.

Aluminum-catalyzed silicon nanowires: Growth methods, properties, and applications

Energy Technology Data Exchange (ETDEWEB)

Hainey, Mel F.; Redwing, Joan M. [Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2016-12-15

Metal-mediated vapor-liquid-solid (VLS) growth is a promising approach for the fabrication of silicon nanowires, although residual metal incorporation into the nanowires during growth can adversely impact electronic properties particularly when metals such as gold and copper are utilized. Aluminum, which acts as a shallow acceptor in silicon, is therefore of significant interest for the growth of p-type silicon nanowires but has presented challenges due to its propensity for oxidation. This paper summarizes the key aspects of aluminum-catalyzed nanowire growth along with wire properties and device results. In the first section, aluminum-catalyzed nanowire growth is discussed with a specific emphasis on methods to mitigate aluminum oxide formation. Next, the influence of growth parameters such as growth temperature, precursor partial pressure, and hydrogen partial pressure on nanowire morphology is discussed, followed by a brief review of the growth of templated and patterned arrays of nanowires. Aluminum incorporation into the nanowires is then discussed in detail, including measurements of the aluminum concentration within wires using atom probe tomography and assessment of electrical properties by four point resistance measurements. Finally, the use of aluminum-catalyzed VLS growth for device fabrication is reviewed including results on single-wire radial p-n junction solar cells and planar solar cells fabricated with nanowire/nanopyramid texturing.

A deep etching mechanism for trench-bridging silicon nanowires.

Science.gov (United States)

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

2016-03-04

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

A deep etching mechanism for trench-bridging silicon nanowires

International Nuclear Information System (INIS)

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

2016-01-01

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

A deep etching mechanism for trench-bridging silicon nanowires

Science.gov (United States)

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

2016-03-01

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

Enhanced sensing of dengue virus DNA detection using O{sub 2} plasma treated-silicon nanowire based electrical biosensor

Energy Technology Data Exchange (ETDEWEB)

Rahman, S.F.A., E-mail: siti_fatimah0410@yahoo.com [Institute of Advanced Technology, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Yusof, N.A., E-mail: azahy@upm.edu.my [Institute of Advanced Technology, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Chemistry Department, Faculty of Science, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Hashim, U. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia); Hushiarian, R. [La Trobe Institute for Molecular Science, La Trobe University, Victoria, 3086 (Australia); Nuzaihan, M.N.M. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia); Hamidon, M.N. [Institute of Advanced Technology, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Zawawi, R.M. [Chemistry Department, Faculty of Science, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Fathil, M.F.M. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia)

2016-10-26

Dengue Virus (DENV) has become one of the most serious arthropod-borne viral diseases, causing death globally. The existing methods for DENV detection suffer from the late stage treatment due to antibodies-based detection which is feasible only after five days following the onset of the illness. Here, we demonstrated the highly effective molecular electronic based detection utilizing silicon nanowire (SiNW) integrated with standard complementary metal-oxide-semiconductor (CMOS) process as a sensing device for detecting deoxyribonucleic acid (DNA) related to DENV in an early stage diagnosis. To transform the fabricated devices as a functional sensing element, three-step procedure consist of SiNW surface modification, DNA immobilization and DNA hybridization were employed. The detection principle works by detecting the changes in current of SiNW which bridge the source and drain terminal to sense the immobilization of probe DNA and their hybridization with target DNA. The oxygen (O{sub 2}) plasma was proposed as an effective strategy for increasing the binding amounts of target DNA by modified the SiNW surface. It was found that the detection limit of the optimized O{sub 2} plasma treated-SiNW device could be reduced to 1.985 × 10{sup −14} M with a linear detection range of the sequence-specific DNA from 1.0 × 10{sup −9} M to 1.0 × 10{sup −13} M. In addition, the developed biosensor device was able to discriminate between complementary, single mismatch and non-complementary DNA sequences. This highly sensitive assay was then applied to the detection of reverse transcription-polymerase chain reaction (RT-PCR) product of DENV-DNA, making it as a potential method for disease diagnosis through electrical biosensor. - Highlights: • Molecular electronic detection of Dengue Virus (DENV) DNA using SiNW biosensor is presented. • Oxygen plasma surface treatment as an enhancer technique for device sensitivity is highlighted. • The limit of detection (Lo

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

A 64-channel readout ASIC for nanowire biosensor array with electrical calibration scheme.

Science.gov (United States)

Chai, Kevin T C; Choe, Kunil; Bernal, Olivier D; Gopalakrishnan, Pradeep K; Zhang, Guo-Jun; Kang, Tae Goo; Je, Minkyu

2010-01-01

A 1.8-mW, 18.5-mm(2) 64-channel current readout ASIC was implemented in 0.18-µm CMOS together with a new calibration scheme for silicon nanowire biosensor arrays. The ASIC consists of 64 channels of dedicated readout and conditioning circuits which incorporate correlated double sampling scheme to reduce the effect of 1/f noise and offset from the analog front-end. The ASIC provides a 10-bit digital output with a sampling rate of 300 S/s whilst achieving a minimum resolution of 7 pA(rms). A new electrical calibration method was introduced to mitigate the issue of large variations in the nano-scale sensor device parameters and optimize the sensor sensitivity. The experimental results show that the proposed calibration technique improved the sensitivity by 2 to 10 times and reduced the variation between dataset by 9 times.

Increasing the efficiency of polymer solar cells by silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

Eisenhawer, B; Sivakov, V; Pietsch, M; Andrae, G; Falk, F [Institute of Photonic Technology, Albert-Einstein-Strasse 9, 07743 Jena (Germany); Sensfuss, S, E-mail: bjoern.eisenhawer@ipht-jena.de [Thuringian Institute for Textile and Plastics Research, Breitscheidstrasse 97, 07407 Rudolstadt (Germany)

2011-08-05

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

Increasing the efficiency of polymer solar cells by silicon nanowires

International Nuclear Information System (INIS)

Eisenhawer, B; Sivakov, V; Pietsch, M; Andrae, G; Falk, F; Sensfuss, S

2011-01-01

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

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

Directory of Open Access Journals (Sweden)

Arancha Gómez-Martínez

2014-01-01

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

Silicon nanowires for ultra-fast and ultrabroadband optical signal processing

DEFF Research Database (Denmark)

Ji, Hua; Hu, Hao; Pu, Minhao

2015-01-01

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

Piezoresistive silicon nanowire resonators as embedded building blocks in thick SOI

Science.gov (United States)

Nasr Esfahani, Mohammad; Kilinc, Yasin; Çagatay Karakan, M.; Orhan, Ezgi; Hanay, M. Selim; Leblebici, Yusuf; Erdem Alaca, B.

2018-04-01

The use of silicon nanowire resonators in nanoelectromechanical systems for new-generation sensing and communication devices faces integration challenges with higher-order structures. Monolithic and deterministic integration of such nanowires with the surrounding microscale architecture within the same thick crystal is a critical aspect for the improvement of throughput, reliability and device functionality. A monolithic and IC-compatible technology based on a tuned combination of etching and protection processes was recently introduced yielding silicon nanowires within a 10 μ m-thick device layer. Motivated by its success, the implications of the technology regarding the electromechanical resonance are studied within a particular setting, where the resonator is co-fabricated with all terminals and tuning electrodes. Frequency response is measured via piezoresistive readout with frequency down-mixing. Measurements indicate mechanical resonance with frequencies as high as 100 MHz exhibiting a Lorentzian behavior with proper transition to nonlinearity, while Allan deviation on the order of 3-8 ppm is achieved. Enabling the fabrication of silicon nanowires in thick silicon crystals using conventional semiconductor manufacturing, the present study thus demonstrates an alternative pathway to bottom-up and thin silicon-on-insulator approaches for silicon nanowire resonators.

Effect of Silicon Nanowire on Crystalline Silicon Solar Cell Characteristics

Directory of Open Access Journals (Sweden)

Zahra Ostadmahmoodi Do

2016-06-01

Full Text Available Nanowires (NWs are recently used in several sensor or actuator devices to improve their ordered characteristics. Silicon nanowire (Si NW is one of the most attractive one-dimensional nanostructures semiconductors because of its unique electrical and optical properties. In this paper, silicon nanowire (Si NW, is synthesized and characterized for application in photovoltaic device. Si NWs are prepared using wet chemical etching method which is commonly used as a simple and low cost method for producing nanowires of the same substrate material. The process conditions are adjusted to find the best quality of Si NWs. Morphology of Si NWs is studied using a field emission scanning electron microscopic technique. An energy dispersive X-Ray analyzer is also used to provide elemental identification and quantitative compositional information. Subsequently, Schottky type solar cell samples are fabricated on Si and Si NWs using ITO and Ag contacts. The junction properties are calculated using I-V curves in dark condition and the solar cell I-V characteristics are obtained under incident of the standardized light of AM1.5. The results for the two mentioned Schottky solar cell samples are compared and discussed. An improvement in short circuit current and efficiency of Schottky solar cell is found when Si nanowires are employed.

Synthesis of silicon nanowires and novel nano-dendrite structures

International Nuclear Information System (INIS)

Sinha, Saion; Gao Bo; Zhou, Otto

2004-01-01

We report a study on the effects of various parameters on the synthesis of silicon nanowires (5--50 nm in diameter) by pulsed laser ablation. A novel silicon nanodendrite structure is observed by changing some of the growth parameters abruptly. This growth mechanism is explained by a qualitative model. These nanodendrites show a promise of being used as a template in fabricating nanocircuits. Thermal quantum confinement effects were also observed on the silicon nanowires and have been reported

Biosensor properties of SOI nanowire transistors with a PEALD Al{sub 2}O{sub 3} dielectric protective layer

Energy Technology Data Exchange (ETDEWEB)

Popov, V. P., E-mail: popov@isp.nsc.ru; Ilnitskii, M. A.; Zhanaev, E. D. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Myakon’kich, A. V.; Rudenko, K. V. [Russian Academy of Sciences, Physical Technological Institute (Russian Federation); Glukhov, A. V. [Novosibirsk Semiconductor Device Plant and Design Bureau (Russian Federation)

2016-05-15

The properties of protective dielectric layers of aluminum oxide Al{sub 2}O{sub 3} applied to prefabricated silicon-nanowire transistor biochips by the plasma enhanced atomic layer deposition (PEALD) method before being housed are studied depending on the deposition and annealing modes. Coating the natural silicon oxide with a nanometer Al{sub 2}O{sub 3} layer insignificantly decreases the femtomole sensitivity of biosensors, but provides their stability in bioliquids. In deionized water, transistors with annealed aluminum oxide are closed due to the trapping of negative charges of <(1–10) × 10{sup 11} cm{sup −2} at surface states. The application of a positive potential to the substrate (V{sub sub} > 25 V) makes it possible to eliminate the negative charge and to perform multiple measurements in liquid at least for half a year.

Origin of noise in liquid-gated Si nanowire troponin biosensors

Science.gov (United States)

Kutovyi, Y.; Zadorozhnyi, I.; Hlukhova, H.; Handziuk, V.; Petrychuk, M.; Ivanchuk, Andriy; Vitusevich, S.

2018-04-01

Liquid-gated Si nanowire field-effect transistor (FET) biosensors are fabricated using a complementary metal-oxide-semiconductor-compatible top-down approach. The transport and noise properties of the devices reflect the high performance of the FET structures, which allows label-free detection of cardiac troponin I (cTnI) molecules. Moreover, after removing the troponin antigens the structures demonstrate the same characteristics as before cTnI detection, indicating the reusable operation of biosensors. Our results show that the additional noise is related to the troponin molecules and has characteristics which considerably differ from those usually recorded for conventional FETs without target molecules. We describe the origin of the noise and suggest that noise spectroscopy represents a powerful tool for understanding molecular dynamic processes in nanoscale FET-based biosensors.

Electrodeposition at room temperature of amorphous silicon and germanium nanowires in ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Martineau, F; Namur, K; Mallet, J; Delavoie, F; Troyon, M; Molinari, M [Laboratoire de Microscopies et d' Etude de Nanostructures (LMEN EA3799), Universite de Reims Champagne Ardennes (URCA), Reims Cedex 2 (France); Endres, F, E-mail: michael.molinari@univ-reims.fr [Institute of Particle Technology, Chair of Interface Processes, Clausthal University of Technology, D-36678 Clausthal-Zellerfeld (Germany)

2009-11-15

The electrodeposition at room temperature of silicon and germanium nanowires from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P{sub 1,4}) containing SiCl{sub 4} as Si source or GeCl{sub 4} as Ge source is investigated by cyclic voltammetry. By using nanoporous polycarbonate membranes as templates, it is possible to reproducibly grow pure silicon and germanium nanowires of different diameters. The nanowires are composed of pure amorphous silicon or germanium. The nanowires have homogeneous cylindrical shape with a roughness of a few nanometres on the wire surfaces. The nanowires' diameters and lengths well match with the initial membrane characteristics. Preliminary photoluminescence experiments exhibit strong emission in the near infrared for the amorphous silicon nanowires.

The field effect transistor DNA biosensor based on ITO nanowires in label-free hepatitis B virus detecting compatible with CMOS technology.

Science.gov (United States)

Shariati, Mohsen

2018-05-15

In this paper the field-effect transistor DNA biosensor for detecting hepatitis B virus (HBV) based on indium tin oxide nanowires (ITO NWs) in label free approach has been fabricated. Because of ITO nanowires intensive conductance and functional modified surface, the probe immobilization and target hybridization were increased strongly. The high resolution transmission electron microscopy (HRTEM) measurement showed that ITO nanowires were crystalline and less than 50nm in diameter. The single-stranded hepatitis B virus DNA (SS-DNA) was immobilized as probe on the Au-modified nanowires. The DNA targets were measured in a linear concentration range from 1fM to 10µM. The detection limit of the DNA biosensor was about 1fM. The time of the hybridization process for defined single strand was 90min. The switching ratio of the biosensor between "on" and "off" state was ~ 1.1 × 10 5 . For sensing the specificity of the biosensor, non-complementary, mismatch and complementary DNA oligonucleotide sequences were clearly discriminated. The HBV biosensor confirmed the highly satisfied specificity for differentiating complementary sequences from non-complementary and the mismatch oligonucleotides. The response time of the DNA sensor was 37s with a high reproducibility. The stability and repeatability of the DNA biosensor showed that the peak current of the biosensor retained 98% and 96% of its initial response for measurements after three and five weeks, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

Structural and optical properties of silicon-carbide nanowires produced by the high-temperature carbonization of silicon nanostructures

Energy Technology Data Exchange (ETDEWEB)

Pavlikov, A. V., E-mail: pavlikov@physics.msu.ru [Moscow State University, Faculty of Physics (Russian Federation); Latukhina, N. V.; Chepurnov, V. I. [Samara National Researh University (Russian Federation); Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation)

2017-03-15

Silicon-carbide (SiC) nanowire structures 40–50 nm in diameter are produced by the high-temperature carbonization of porous silicon and silicon nanowires. The SiC nanowires are studied by scanning electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and infrared reflectance spectroscopy. The X-ray structural and Raman data suggest that the cubic 3C-SiC polytype is dominant in the samples under study. The shape of the infrared reflectance spectrum in the region of the reststrahlen band 800–900 cm{sup –1} is indicative of the presence of free charge carriers. The possibility of using SiC nanowires in microelectronic, photonic, and gas-sensing devices is discussed.

Unveiling the Formation Pathway of Single Crystalline Porous Silicon Nanowires

Science.gov (United States)

Zhong, Xing; Qu, Yongquan; Lin, Yung-Chen; Liao, Lei; Duan, Xiangfeng

2011-01-01

Porous silicon nanowire is emerging as an interesting material system due to its unique combination of structural, chemical, electronic, and optical properties. To fully understand their formation mechanism is of great importance for controlling the fundamental physical properties and enabling potential applications. Here we present a systematic study to elucidate the mechanism responsible for the formation of porous silicon nanowires in a two-step silver-assisted electroless chemical etching method. It is shown that silicon nanowire arrays with various porosities can be prepared by varying multiple experimental parameters such as the resistivity of the starting silicon wafer, the concentration of oxidant (H2O2) and the amount of silver catalyst. Our study shows a consistent trend that the porosity increases with the increasing wafer conductivity (dopant concentration) and oxidant (H2O2) concentration. We further demonstrate that silver ions, formed by the oxidation of silver, can diffuse upwards and re-nucleate on the sidewalls of nanowires to initiate new etching pathways to produce porous structure. The elucidation of this fundamental formation mechanism opens a rational pathway to the production of wafer-scale single crystalline porous silicon nanowires with tunable surface areas ranging from 370 m2·g−1 to 30 m2·g−1, and can enable exciting opportunities in catalysis, energy harvesting, conversion, storage, as well as biomedical imaging and therapy. PMID:21244020

Silicon nanowire hot carrier electroluminescence

Energy Technology Data Exchange (ETDEWEB)

Plessis, M. du, E-mail: monuko@up.ac.za; Joubert, T.-H.

2016-08-31

Avalanche electroluminescence from silicon pn junctions has been known for many years. However, the internal quantum efficiencies of these devices are quite low due to the indirect band gap nature of the semiconductor material. In this study we have used reach-through biasing and SOI (silicon-on-insulator) thin film structures to improve the internal power efficiency and the external light extraction efficiency. Both continuous silicon thin film pn junctions and parallel nanowire pn junctions were manufactured using a custom SOI technology. The pn junctions are operated in the reach-through mode of operation, thus increasing the average electric field within the fully depleted region. Experimental results of the emission spectrum indicate that the most dominant photon generating mechanism is due to intraband hot carrier relaxation processes. It was found that the SOI nanowire light source external power efficiency is at least an order of magnitude better than the comparable bulk CMOS (Complementary Metal Oxide Semiconductor) light source. - Highlights: • We investigate effect of electric field on silicon avalanche electroluminescence. • With reach-through pn junctions the current and carrier densities are kept constant. • Higher electric fields increase short wavelength radiation. • Higher electric fields decrease long wavelength radiation. • The effect of the electric field indicates intraband transitions as main mechanism.

Silicon nanowire structures as high-sensitive pH-sensors

International Nuclear Information System (INIS)

Belostotskaya, S O; Chuyko, O V; Kuznetsov, A E; Kuznetsov, E V; Rybachek, E N

2012-01-01

Sensitive elements for pH-sensors created on silicon nanostructures were researched. Silicon nanostructures have been used as ion-sensitive field effect transistor (ISFET) for the measurement of solution pH. Silicon nanostructures have been fabricated by 'top-down' approach and have been studied as pH sensitive elements. Nanowires have the higher sensitivity. It was shown, that sensitive element, which is made of 'one-dimensional' silicon nanostructure have bigger pH-sensitivity as compared with 'two-dimensional' structure. Integrated element formed from two p- and n-type nanowire ISFET ('inverter') can be used as high sensitivity sensor for local relative change [H+] concentration in very small volume.

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.

Broadband Nonlinear Signal Processing in Silicon Nanowires

DEFF Research Database (Denmark)

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

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

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

DEFF Research Database (Denmark)

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

2012-01-01

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

Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence

International Nuclear Information System (INIS)

Duraia, El-Shazly M.; Mansurov, Z.A.; Tokmolden, S.; Beall, Gary W.

2010-01-01

In this work we report the successful formation of highly aligned vertical silicon oxide nanowires. The source of silicon was from the substrate itself without any additional source of silicon. X-ray measurement demonstrated that our nanowires are amorphous. Photoluminescence measurements were conducted through 18 months and indicated that there is a very good intensive emission peaks near the violet regions. The FTIR measurements indicated the existence of peaks at 463, 604, 795 and a wide peak at 1111 cm -1 and this can be attributed to Si-O-Si and Si-O stretching vibrations. We also report the formation of the octopus-like silicon oxide nanowires and the growth mechanism of these structures was discussed.

Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence

Energy Technology Data Exchange (ETDEWEB)

Duraia, El-Shazly M., E-mail: duraia_physics@yahoo.co [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Mansurov, Z.A. [Al-Farabi Kazakh National University, Almaty (Kazakhstan); Tokmolden, S. [Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Beall, Gary W. [Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666 (United States)

2010-02-15

In this work we report the successful formation of highly aligned vertical silicon oxide nanowires. The source of silicon was from the substrate itself without any additional source of silicon. X-ray measurement demonstrated that our nanowires are amorphous. Photoluminescence measurements were conducted through 18 months and indicated that there is a very good intensive emission peaks near the violet regions. The FTIR measurements indicated the existence of peaks at 463, 604, 795 and a wide peak at 1111 cm{sup -1} and this can be attributed to Si-O-Si and Si-O stretching vibrations. We also report the formation of the octopus-like silicon oxide nanowires and the growth mechanism of these structures was discussed.

Global optimization of silicon nanowires for efficient parametric processes

DEFF Research Database (Denmark)

Vukovic, Dragana; Xu, Jing; Mørk, Jesper

2013-01-01

We present a global optimization of silicon nanowires for parametric single-pump mixing. For the first time, the effect of surface roughness-induced loss is included in the analysis, significantly influencing the optimum waveguide dimensions.......We present a global optimization of silicon nanowires for parametric single-pump mixing. For the first time, the effect of surface roughness-induced loss is included in the analysis, significantly influencing the optimum waveguide dimensions....

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-28

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

Rhodium Nanoparticle-mesoporous Silicon Nanowire Nanohybrids for Hydrogen Peroxide Detection with High Selectivity

Science.gov (United States)

Song, Zhiqian; Chang, Hucheng; Zhu, Weiqin; Xu, Chenlong; Feng, Xinjian

2015-01-01

Developing nanostructured electrocatalysts, with low overpotential, high selectivity and activity has fundamental and technical importance in many fields. We report here rhodium nanoparticle and mesoporous silicon nanowire (RhNP@mSiNW) hybrids for hydrogen peroxide (H2O2) detection with high electrocatalytic activity and selectivity. By employing electrodes that loaded with RhNP@mSiNW nanohybrids, interference caused from both many electroactive substances and dissolved oxygen were eliminated by electrochemical assaying at an optimal potential of +75 mV. Furthermore, the electrodes exhibited a high detection sensitivity of 0.53 μA/mM and fast response (< 5 s). This high-performance nanohybrid electrocatalyst has great potential for future practical application in various oxidase-base biosensors. PMID:25588953

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

International Nuclear Information System (INIS)

Li, Hung-Hsien; Yang, Chi-En; Kei, Chi-Chung; Su, Chung-Yi; Dai, Wei-Syuan; Tseng, Jung-Kuei; Yang, Po-Yu; Chou, Jung-Chuan; Cheng, Huang-Chung

2013-01-01

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

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.

Single cell detection using a magnetic zigzag nanowire biosensor.

Science.gov (United States)

Huang, Hao-Ting; Ger, Tzong-Rong; Lin, Ya-Hui; Wei, Zung-Hang

2013-08-07

A magnetic zigzag nanowire device was designed for single cell biosensing. Nanowires with widths of 150, 300, 500, and 800 nm were fabricated on silicon trenches by electron beam lithography, electron beam evaporation, and lift-off processes. Magnetoresistance measurements were performed before and after the attachment of a single magnetic cell to the nanowires to characterize the magnetic signal change due to the influence of the magnetic cell. Magnetoresistance responses were measured in different magnetic field directions, and the results showed that this nanowire device can be used for multi-directional detection. It was observed that the highest switching field variation occurred in a 150 nm wide nanowire when the field was perpendicular to the substrate plane. On the other hand, the highest magnetoresistance ratio variation occurred in a 800 nm wide nanowire also when the field was perpendicular to the substrate plane. Besides, the trench-structured substrate proposed in this study can fix the magnetic cell to the sensor in a fluid environment, and the stray field generated by the corners of the magnetic zigzag nanowires has the function of actively attracting the magnetic cells for detection.

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

International Nuclear Information System (INIS)

Congli, Sun; Hao, Hu; Huanhuan, Feng; Jingjing, Xu; Yu, Chen; Yong, Jin; Zhifeng, Jiao; Xiaosong, Sun

2013-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-10-01

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

Last Advances in Silicon-Based Optical Biosensors

Directory of Open Access Journals (Sweden)

Adrián Fernández Gavela

2016-02-01

Full Text Available We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies.

Last Advances in Silicon-Based Optical Biosensors.

Science.gov (United States)

Fernández Gavela, Adrián; Grajales García, Daniel; Ramirez, Jhonattan C; Lechuga, Laura M

2016-02-24

We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies.

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

Directory of Open Access Journals (Sweden)

Britta Kämpken

2012-07-01

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

Generation of Reactive Oxygen Species from Silicon Nanowires

Directory of Open Access Journals (Sweden)

Stephen S. Leonard

2014-01-01

Full Text Available Processing and synthesis of purified nanomaterials of diverse composition, size, and properties is an evolving process. Studies have demonstrated that some nanomaterials have potential toxic effects and have led to toxicity research focusing on nanotoxicology. About two million workers will be employed in the field of nanotechnology over the next 10 years. The unknown effects of nanomaterials create a need for research and development of techniques to identify possible toxicity. Through a cooperative effort between National Institute for Occupational Safety and Health and IBM to address possible occupational exposures, silicon-based nanowires (SiNWs were obtained for our study. These SiNWs are anisotropic filamentary crystals of silicon, synthesized by the vapor-liquid-solid method and used in bio-sensors, gas sensors, and field effect transistors. Reactive oxygen species (ROS can be generated when organisms are exposed to a material causing cellular responses, such as lipid peroxidation, H 2 O 2 production, and DNA damage. SiNWs were assessed using three different in vitro environments (H 2 O 2 , RAW 264.7 cells, and rat alveolar macrophages for ROS generation and possible toxicity identification. We used electron spin resonance, analysis of lipid peroxidation, measurement of H 2 O 2 production, and the comet assay to assess generation of ROS from SiNW and define possible mechanisms. Our results demonstrate that SiNWs do not appear to be significant generators of free radicals.

Surface Patterning and Nanowire Biosensor Construction

DEFF Research Database (Denmark)

Iversen, Lars

2008-01-01

surface. A central limitation to this biosensor principle is the screening of analyte charge by mobile ions in electrolytes with physiological ionic strength. To overcome this problem, we propose to use as capture agents proteins which undergo large conformational changes. Using structure based protein...... charge prediction, we show how ligand induced changes in conformation of two model proteins, both being ligand binding domains from glutamate receptors, can lead to changes in electrostatic potential predicted to be sufficient for NW sensing. Finally we, demonstrate how InAs nanowires can....... In part I - “Surface Patterning” - glass and gold surfaces serve as spatially encoded immobilization supports for patterning of recombinant proteins and organic monolayers. First, we combine micro-contact printing with a reactive SNAP-tag protein to establish a general platform for templated protein...

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

KAUST Repository

Cui, Li-Feng; Yang, Yuan; Hsu, Ching-Mei; Cui, Yi

2009-01-01

We introduce a novel design of carbon-silicon core-shell nanowires for high power and long life lithium battery electrodes. Amorphous silicon was coated onto carbon nanofibers to form a core-shell structure and the resulted core-shell nanowires

Solution-grown silicon nanowires for lithium-ion battery anodes.

Science.gov (United States)

Chan, Candace K; Patel, Reken N; O'Connell, Michael J; Korgel, Brian A; Cui, Yi

2010-03-23

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

Solution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes

KAUST Repository

Chan, Candace K.

2010-03-23

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

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

KAUST Repository

Cui, Li-Feng

2009-09-09

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

Ultra-low reflection porous silicon nanowires for solar cell applications

OpenAIRE

Najar , Adel; Charrier , Joël; Pirasteh , Parastesh; Sougrat , R.

2012-01-01

International audience; High density vertically aligned Porous Silicon NanoWires (PSiNWs) were fabricated on silicon substrate using metal assisted chemical etching process. A linear dependency of nanowire length to the etching time was obtained and the change in the growth rate of PSiNWs by increasing etching durations was shown. A typical 2D bright-field TEM image used for volume reconstruction of the sample shows the pores size varying from 10 to 50 nm. Furthermore, reflectivity measuremen...

Progress of new label-free techniques for biosensors: a review.

Science.gov (United States)

Sang, Shengbo; Wang, Yajun; Feng, Qiliang; Wei, Ye; Ji, Jianlong; Zhang, Wendong

2016-01-01

The detection techniques used in biosensors can be broadly classified into label-based and label-free. Label-based detection relies on the specific properties of labels for detecting a particular target. In contrast, label-free detection is suitable for the target molecules that are not labeled or the screening of analytes which are not easy to tag. Also, more types of label-free biosensors have emerged with developments in biotechnology. The latest developed techniques in label-free biosensors, such as field-effect transistors-based biosensors including carbon nanotube field-effect transistor biosensors, graphene field-effect transistor biosensors and silicon nanowire field-effect transistor biosensors, magnetoelastic biosensors, optical-based biosensors, surface stress-based biosensors and other type of biosensors based on the nanotechnology are discussed. The sensing principles, configurations, sensing performance, applications, advantages and restriction of different label-free based biosensors are considered and discussed in this review. Most concepts included in this survey could certainly be applied to the development of this kind of biosensor in the future.

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

International Nuclear Information System (INIS)

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

2016-01-01

In this work, we report an enhanced nitrogen dioxide (NO 2 ) gas sensor based on tungsten oxide (WO 3 ) nanowires/porous silicon (PS) decorated with gold (Au) nanoparticles. Au-loaded WO 3 nanowires with diameters of 10 nm–25 nm and lengths of 300 nm–500 nm are fabricated by the sputtering method on a porous silicon substrate. The high-resolution transmission electron microscopy (HRTEM) micrographs show that Au nanoparticles are uniformly distributed on the surfaces of WO 3 nanowires. The effect of the Au nanoparticles on the NO 2 -sensing performance of WO 3 nanowires/porous silicon is investigated over a low concentration range of 0.2 ppm–5 ppm of NO 2 at room temperature (25 °C). It is found that the 10-Å Au-loaded WO 3 nanowires/porous silicon-based sensor possesses the highest gas response characteristic. The underlying mechanism of the enhanced sensing properties of the Au-loaded WO 3 nanowires/porous silicon is also discussed. (paper)

A III-V nanowire channel on silicon for high-performance vertical transistors.

Science.gov (United States)

Tomioka, Katsuhiro; Yoshimura, Masatoshi; Fukui, Takashi

2012-08-09

Silicon transistors are expected to have new gate architectures, channel materials and switching mechanisms in ten years' time. The trend in transistor scaling has already led to a change in gate structure from two dimensions to three, used in fin field-effect transistors, to avoid problems inherent in miniaturization such as high off-state leakage current and the short-channel effect. At present, planar and fin architectures using III-V materials, specifically InGaAs, are being explored as alternative fast channels on silicon because of their high electron mobility and high-quality interface with gate dielectrics. The idea of surrounding-gate transistors, in which the gate is wrapped around a nanowire channel to provide the best possible electrostatic gate control, using InGaAs channels on silicon, however, has been less well investigated because of difficulties in integrating free-standing InGaAs nanostructures on silicon. Here we report the position-controlled growth of vertical InGaAs nanowires on silicon without any buffering technique and demonstrate surrounding-gate transistors using InGaAs nanowires and InGaAs/InP/InAlAs/InGaAs core-multishell nanowires as channels. Surrounding-gate transistors using core-multishell nanowire channels with a six-sided, high-electron-mobility transistor structure greatly enhance the on-state current and transconductance while keeping good gate controllability. These devices provide a route to making vertically oriented transistors for the next generation of field-effect transistors and may be useful as building blocks for wireless networks on silicon platforms.

Silicon Nanowire Field-effect Chemical Sensor

NARCIS (Netherlands)

Chen, S.

2011-01-01

This thesis describes the work that has been done on the project “Design and optimization of silicon nanowire for chemical sensing‿, including Si-NW fabrication, electrical/electrochemical modeling, the application as ISFET, and the build-up of Si- NW/LOC system for automatic sample delivery. A

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.

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....

An ultrasensitive electrochemical DNA biosensor based on a copper oxide nanowires/single-walled carbon nanotubes nanocomposite

International Nuclear Information System (INIS)

Chen, Mei; Hou, Changjun; Huo, Danqun; Yang, Mei; Fa, Huanbao

2016-01-01

Graphical abstract: A novel and sensitive electrochemical biosensor based on hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH) was first developed for the detection of the specific-sequence target DNA. This schematic represents the fabrication procedure of our DNA biosensor. - Highlights: • An ultrasensitive DNA electrochemical biosensor was developed. • CuO NWs entangled with the SWCNTs formed a mesh structure with good conductivity. • It is the first time use of CuONWs-SWCNTs hybrid nanocomposite for DNA detection. • The biosensor is simple, selective, stable, and sensitive. • The biosensor has great potential for use in analysis of real samples. - Abstract: Here, we developed a novel and sensitive electrochemical biosensor to detect specific-sequence target DNA. The biosensor was based on a hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH). The resulting CuO NWs/SWCNTs layers exhibited a good differential pulse voltammetry (DPV) current response for the target DNA sequences, which we attributed to the properties of CuO NWs and SWCNTs. CuO NWs and SWCNTs hybrid composites with highly conductive and biocompatible nanostructure were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cyclic voltammetry (CV). Immobilization of the probe DNA on the electrode surface was largely improved due to the unique synergetic effect of CuO NWs and SWCNTs. DPV was applied to monitor the DNA hybridization event, using adriamycin as an electrochemical indicator. Under optimal conditions, the peak currents of adriamycin were linear with the logarithm of target DNA concentrations (ranging from 1.0 × 10"−"1"4 to 1.0 × 10"−"8 M), with a detection limit of 3.5 × 10"−"1"5 M (signal/noise ratio of 3). The biosensor also showed high selectivity to

An ultrasensitive electrochemical DNA biosensor based on a copper oxide nanowires/single-walled carbon nanotubes nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Chen, Mei [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Hou, Changjun, E-mail: houcj@cqu.edu.cn [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); National Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology, Chongqing University, Chongqing 400044 (China); Huo, Danqun [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); National Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology, Chongqing University, Chongqing 400044 (China); Yang, Mei [Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Fa, Huanbao [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China)

2016-02-28

Graphical abstract: A novel and sensitive electrochemical biosensor based on hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH) was first developed for the detection of the specific-sequence target DNA. This schematic represents the fabrication procedure of our DNA biosensor. - Highlights: • An ultrasensitive DNA electrochemical biosensor was developed. • CuO NWs entangled with the SWCNTs formed a mesh structure with good conductivity. • It is the first time use of CuONWs-SWCNTs hybrid nanocomposite for DNA detection. • The biosensor is simple, selective, stable, and sensitive. • The biosensor has great potential for use in analysis of real samples. - Abstract: Here, we developed a novel and sensitive electrochemical biosensor to detect specific-sequence target DNA. The biosensor was based on a hybrid nanocomposite consisting of copper oxide nanowires (CuO NWs) and carboxyl-functionalized single-walled carbon nanotubes (SWCNTs-COOH). The resulting CuO NWs/SWCNTs layers exhibited a good differential pulse voltammetry (DPV) current response for the target DNA sequences, which we attributed to the properties of CuO NWs and SWCNTs. CuO NWs and SWCNTs hybrid composites with highly conductive and biocompatible nanostructure were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cyclic voltammetry (CV). Immobilization of the probe DNA on the electrode surface was largely improved due to the unique synergetic effect of CuO NWs and SWCNTs. DPV was applied to monitor the DNA hybridization event, using adriamycin as an electrochemical indicator. Under optimal conditions, the peak currents of adriamycin were linear with the logarithm of target DNA concentrations (ranging from 1.0 × 10{sup −14} to 1.0 × 10{sup −8} M), with a detection limit of 3.5 × 10{sup −15} M (signal/noise ratio of 3). The biosensor also showed high

Modulation of thermal conductivity in kinked silicon nanowires: phonon interchanging and pinching effects.

Science.gov (United States)

Jiang, Jin-Wu; Yang, Nuo; Wang, Bing-Shen; Rabczuk, Timon

2013-04-10

We perform molecular dynamics simulations to investigate the reduction of the thermal conductivity by kinks in silicon nanowires. The reduction percentage can be as high as 70% at room temperature. The temperature dependence of the reduction is also calculated. By calculating phonon polarization vectors, two mechanisms are found to be responsible for the reduced thermal conductivity: (1) the interchanging effect between the longitudinal and transverse phonon modes and (2) the pinching effect, that is, a new type of localization, for the twisting and transverse phonon modes in the kinked silicon nanowires. Our work demonstrates that the phonon interchanging and pinching effects, induced by kinking, are brand-new and effective ways in modulating heat transfer in nanowires, which enables the kinked silicon nanowires to be a promising candidate for thermoelectric materials.

System-level integration of active silicon photonic biosensors

Science.gov (United States)

Laplatine, L.; Al'Mrayat, O.; Luan, E.; Fang, C.; Rezaiezadeh, S.; Ratner, D. M.; Cheung, K.; Dattner, Y.; Chrostowski, L.

2017-02-01

Biosensors based on silicon photonic integrated circuits have attracted a growing interest in recent years. The use of sub-micron silicon waveguides to propagate near-infrared light allows for the drastic reduction of the optical system size, while increasing its complexity and sensitivity. Using silicon as the propagating medium also leverages the fabrication capabilities of CMOS foundries, which offer low-cost mass production. Researchers have deeply investigated photonic sensor devices, such as ring resonators, interferometers and photonic crystals, but the practical integration of silicon photonic biochips as part of a complete system has received less attention. Herein, we present a practical system-level architecture which can be employed to integrate the aforementioned photonic biosensors. We describe a system based on 1 mm2 dies that integrate germanium photodetectors and a single light coupling device. The die are embedded into a 16x16 mm2 epoxy package to enable microfluidic and electrical integration. First, we demonstrate a simple process to mimic Fan-Out Wafer-level-Packaging, which enables low-cost mass production. We then characterize the photodetectors in the photovoltaic mode, which exhibit high sensitivity at low optical power. Finally, we present a new grating coupler concept to relax the lateral alignment tolerance down to +/- 50 μm at 1-dB (80%) power penalty, which should permit non-experts to use the biochips in a"plug-and-play" style. The system-level integration demonstrated in this study paves the way towards the mass production of low-cost and highly sensitive biosensors, and can facilitate their wide adoption for biomedical and agro-environmental applications.

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

Directory of Open Access Journals (Sweden)

Ramon M. delos Santos

2008-06-01

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

Porous silicon localization for implementation in matrix biosensors

International Nuclear Information System (INIS)

Benilov, A.; Cabrera, M.; Skryshevsky, V.; Martin, J.-R.

2007-01-01

The search of appropriate substrates and methods of surface DNA functionalisation is one of the important tasks of semiconductor biosensors. In this work we develop a method of light-assisted porous silicon etching in order to localize porous silicon spots on silicon substrate for matrix fluorophore-labeled DNA sensors implementation. The principal difference of porous spots localization proposed is considered for n- and p-type Si substrates under the condition of supplementary illumination. The tuning of the porous profile via applying of lateral electric field is proposed and experimentally proved

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

KAUST Repository

Chan, Candace K.

2009-04-01

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

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

Science.gov (United States)

Saranti, Konstantina; Alotaibi, Sultan; Paul, Shashi

2016-06-01

The work described in this paper focuses on the utilisation of silicon nanowires as the information storage element in flash-type memory devices. Silicon nanostructures have attracted attention due to interesting electrical and optical properties, and their potential integration into electronic devices. A detailed investigation of the suitability of silicon nanowires as the charge storage medium in two-terminal non-volatile memory devices are presented in this report. The deposition of the silicon nanostructures was carried out at low temperatures (less than 400 °C) using a previously developed a novel method within our research group. Two-terminal non-volatile (2TNV) memory devices and metal-insulator-semiconductor (MIS) structures containing the silicon nanowires were fabricated and an in-depth study of their characteristics was carried out using current-voltage and capacitance techniques.

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

Scattering cross section of metal catalyst atoms in silicon nanowires

DEFF Research Database (Denmark)

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

2010-01-01

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

A novel nitrite biosensor based on the direct electron transfer hemoglobin immobilized in the WO3 nanowires with high length–diameter ratio

International Nuclear Information System (INIS)

Liu, Hui; Duan, Congyue; Yang, Chenhui; Chen, Xianjin; Shen, Wanqiu; Zhu, Zhenfeng

2015-01-01

WO 3 nanowires (WO 3 NWs) with high length–diameter ratio have been synthesized through a simple synthetic route without any additive and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of WO 3 NWs were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Spectroscopic and electrochemical results revealed that WO 3 NWs are an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Meanwhile, due to unique morphology and property of the WO 3 nanowires, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of nitrite with a wide linear range of 1 to 4200 μM, as well as an extremely low detection limit of 0.28 μM. The WO 3 nanowires with high length–diameter ratio could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in environmental analysis and biomedical detection. - Highlights: • The WO 3 NWs with high length–diameter ratio have been synthesized. • The WO 3 NWs were used to immobilize Hb to fabricate a mediator-free biosensor. • The biosensor displays a wide linear range of 1–4200 μM for nitrite. • The biosensor exhibits an extremely low detection limit of 0.28 μM for nitrite

Investigation of functionalized silicon nanowires by self-assembled monolayer

Energy Technology Data Exchange (ETDEWEB)

Hemed, Nofar Mintz [Dept. of Physical Electronics, Eng. Faculty, and the University Res. Inst. for Nano Science and Nano-Technologies, Tel-Aviv University, Ramat-Aviv 69978 (Israel); Convertino, Annalisa [Istituto per la Microelettronica e i Microsistemi C.N.R.-Area della Ricerca di Roma, via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Shacham-Diamand, Yosi [Dept. of Physical Electronics, Eng. Faculty, and the University Res. Inst. for Nano Science and Nano-Technologies, Tel-Aviv University, Ramat-Aviv 69978 (Israel); The Department of Applied Chemistry, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)

2016-03-30

Graphical abstract: - Highlights: • We characterize and verify the existence of self-assembled monolayer (SAM) on silicon nanowires and α-Si:H. • We define the term “electrical coverage” and find the formula for both cases. • The SAM's electrical coverage on silicon nanowires is found to be ∼63%. • The SAM's electrical coverage on α-Si:H is found to be ∼65 ± 3%. • The amount of SAM on the SiNWs is sufficient and it can serve as a linker to biological molecules. - Abstract: The functionalization using self assembled monolayer (SAM) of silicon nanowires (SiNW) fabricated by plasma enhanced chemical vapor deposition (PECVD) is reported here. The SAM is being utilized as the first building block in the functionalization process. The morphology of the SiNW comprises a polycrystalline core wrapped by an hydrogenated amorphous silicon (α-Si:H) shell. Since most of the available methods for SAM verification and characterization are suitable only for flat substrates; therefore, in addition to the SiNW α-Si:H on flat samples were produced in the same system as the SiNWs. First we confirmed the SAM's presence on the flat α-Si:H samples using the following methods: contact angle measurement to determine the change in surface energy; atomic force microscopy (AFM) to determine uniformity and molecular coverage. Spectroscopic ellipsometry and X-ray reflectivity (XRR) were performed to measure SAM layer thickness and density. X-ray photoelectron spectroscopy (XPS) was applied to study the chemical states of the surface. Next, SiNW/SAM were tested by electrochemical impedance spectroscopy (EIS), and the results were compared to α-Si:H/SAM. The SAM electrical coverage on SiNW and α-Si:H was found to be ∼37% and ∼65 ± 3%, respectively. A model, based on transmission line theory for the nanowires is presented to explain the disparity in results between the nanowires and flat surface of the same materials.

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.

Surface functionalization of HF-treated silicon nanowires

Indian Academy of Sciences (India)

Administrator

place when silicon nanowires reacted with 2,2,2-trifluoroethyl acrylate, and reductive deposition reaction occurred in the ... detection of fM level of protein. 14 and DNA. 15 ... surfaces can be easily modified to act as both elec- tron-transfer ...

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

KAUST Repository

Chan, Candace K.; Ruffo, Riccardo; Hong, Seung Sae; Huggins, Robert A.; Cui, Yi

2009-01-01

The structural transformations of silicon nanowires when cycled against lithium were evaluated using electrochemical potential spectroscopy and galvanostatic cycling. During the charge, the nanowires alloy with lithium to form an amorphous Lix

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.

Assessment on thermoelectric power factor in silicon nanowire networks

Energy Technology Data Exchange (ETDEWEB)

Lohn, Andrew J.; Kobayashi, Nobuhiko P. [Baskin School of Engineering, University of California Santa Cruz, CA (United States); Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California Santa Cruz, NASA Ames Research Center, Moffett Field, CA (United States); Coleman, Elane; Tompa, Gary S. [Structured Materials Industries, Inc., Piscataway, NJ (United States)

2012-01-15

Thermoelectric devices based on three-dimensional networks of highly interconnected silicon nanowires were fabricated and the parameters that contribute to the power factor, namely the Seebeck coefficient and electrical conductivity were assessed. The large area (2 cm x 2 cm) devices were fabricated at low cost utilizing a highly scalable process involving silicon nanowires grown on steel substrates. Temperature dependence of the Seebeck coefficient was found to be weak over the range of 20-80 C at approximately -400 {mu}V/K for unintentionally doped devices and {+-}50 {mu}V/K for p-type and n-type devices, respectively. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

A novel nitrite biosensor based on the direct electron transfer hemoglobin immobilized in the WO{sub 3} nanowires with high length–diameter ratio

Energy Technology Data Exchange (ETDEWEB)

Liu, Hui, E-mail: liuhui@sust.edu.cn; Duan, Congyue; Yang, Chenhui; Chen, Xianjin; Shen, Wanqiu; Zhu, Zhenfeng

2015-08-01

WO{sub 3} nanowires (WO{sub 3}NWs) with high length–diameter ratio have been synthesized through a simple synthetic route without any additive and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of WO{sub 3}NWs were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Spectroscopic and electrochemical results revealed that WO{sub 3}NWs are an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Meanwhile, due to unique morphology and property of the WO{sub 3} nanowires, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of nitrite with a wide linear range of 1 to 4200 μM, as well as an extremely low detection limit of 0.28 μM. The WO{sub 3} nanowires with high length–diameter ratio could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in environmental analysis and biomedical detection. - Highlights: • The WO{sub 3}NWs with high length–diameter ratio have been synthesized. • The WO{sub 3}NWs were used to immobilize Hb to fabricate a mediator-free biosensor. • The biosensor displays a wide linear range of 1–4200 μM for nitrite. • The biosensor exhibits an extremely low detection limit of 0.28 μM for nitrite.

Metal-Catalyst-Free Synthesis and Characterization of Single-Crystalline Silicon Oxynitride Nanowires

Directory of Open Access Journals (Sweden)

Shuang Xi

2012-01-01

Full Text Available Large quantities of single-crystal silicon oxynitride nanowires with high N concentration have been synthesized directly on silicon substrate at 1200°C without using any metal catalyst. The diameter of these ternary nanowires is ranging from 10 to 180 nm with log-normal distribution, and the length of these nanowires varies from a few hundreds of micrometers to several millimeters. A vapor-solid mechanism was proposed to explain the growth of the nanowires. These nanowires are grown to form a disordered mat with an ultrabright white nonspecular appearance. The mat demonstrates highly diffusive reflectivity with the optical reflectivity of around 80% over the whole visible wavelength, which is comparable to the most brilliant white beetle scales found in nature. The whiteness might be resulted from the strong multiscattering of a large fraction of incident light on the disordered nanowire mat. These ultra-bright white nanowires could form as reflecting surface to meet the stringent requirements of bright-white light-emitting-diode lighting for higher optical efficiency. They can also find applications in diverse fields such as sensors, cosmetics, paints, and tooth whitening.

First-principles study of structural & electronic properties of pyramidal silicon nanowire

Energy Technology Data Exchange (ETDEWEB)

Jariwala, Pinank; Thakor, P. B. [Department of Physics, Veer Narmad South Gujarat University, Surat 395 007, Gujarat (India); Singh, Deobrat; Sonvane, Y. A., E-mail: yasonvane@gmail.com [Department of Applied Physics, S. V. National Institute of Technology, Surat 395 007 (India); Gupta, Sanjeev K. [Department of Physics, St. Xavier’s College, Ahmedabad 38 0009 (India)

2016-05-23

We have investigated the stable structural and electronic properties of Silicon (Si) nanowires having different cross-sections with 5-7 Si atoms per unit cell. These properties of the studied Si nanowires were significantly changed from those of diamond bulk Si structure. The binding energy increases as increasing atoms number per unit cell in different SiNWs structures. All the nanowires structures are behave like metallic rather than semiconductor in bulk systems. In general, the number of conduction channels increases when the nanowire becomes thicker. The density of charge revealed delocalized metallic bonding for all studied Si nanowires.

Room temperature photoluminescence in the visible range from silicon nanowires grown by a solid-state reaction

International Nuclear Information System (INIS)

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

2009-01-01

The solid-liquid-solid method (also known as the solid-state method) is used to produce silicon nanowires at the core of silica nanowires with a support catalyst layer structure of nickel and titanium layers sputtered on oxide-coated silicon wafers. This silane-free process is low cost and large-area compatible. Using electron microscopy and Raman spectroscopy we deduce that the wires have crystalline silicon cores. The nanowires show photoluminescence in the visible range (orange), and we investigate the origin of this band. We further show that the nanowires form a random mesh that acts as an efficient optical trap, giving rise to an optically absorbing medium.

Room temperature photoluminescence in the visible range from silicon nanowires grown by a solid-state reaction

Science.gov (United States)

Anguita, J. V.; Sharma, P.; Henley, S. J.; Silva, S. R. P.

2009-11-01

The solid-liquid-solid method (also known as the solid-state method) is used to produce silicon nanowires at the core of silica nanowires with a support catalyst layer structure of nickel and titanium layers sputtered on oxide-coated silicon wafers. This silane-free process is low cost and large-area compatible. Using electron microscopy and Raman spectroscopy we deduce that the wires have crystalline silicon cores. The nanowires show photoluminescence in the visible range (orange), and we investigate the origin of this band. We further show that the nanowires form a random mesh that acts as an efficient optical trap, giving rise to an optically absorbing medium.

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

Chemically Etched Silicon Nanowires as Anodes for Lithium-Ion Batteries

Energy Technology Data Exchange (ETDEWEB)

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

2015-08-01

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

Organophosphonate functionalized silicon nanowires for DNA hybridization studies

Energy Technology Data Exchange (ETDEWEB)

Pedone, Daniel; Cattani Scholz, Anna; Birner, Stefan; Abstreiter, Gerhard [WSI, TU Muenchen (Germany); Dubey, Manish; Schwartz, Jeffrey [Princeton University, NJ (United States); Tornow, Marc [IHT, TU Braunschweig (Germany)

2007-07-01

Semiconductor nanowire field effect devices have great appeal for label-free sensing applications due to their sensitivity to surface potential changes that may originate from charged adsorbates. In addition to requiring high sensitivity, suitable passivation and functionalization of the semiconductor surface is obligatory. We have fabricated both freely suspended and oxide-supported silicon nanowires from Silicon-on-Insulator substrates using standard nanopatterning methods (EBL, RIE) and sacrificial oxide layer etching. Subsequent to nanofabrication, the devices were first coated with an hydroxyalkylphosphonate monolayer and then bound via bifunctional linker groups to single stranded DNA or PNA oligonucleotides, respectively. We investigated DNA hybridization on such functionalized nanowires using a difference resistance setup, where subtracting the reference signal from a second wire could be used to exclude most non-specific effects. A net change in surface potential on the order of a few mV could be detected upon addition of the complementary DNA strand. This surface potential change corresponds to the hybridization of about 10{sup 10}cm{sup -2} probe strands according to our model calculations that takes into account the entire hybrid system in electrolyte solution.

The electronic structure of radial p-n junction silicon nanowires

Science.gov (United States)

Chiou, Shan-Haw; Grossman, Jeffrey

2007-03-01

Silicon nanowires with radial p-n junctions have recently been suggested for photovoltaic applications because incident light can be absorbed along the entire length of the wire, while photogenerated carriers only need to diffuse a maximum of one radius to reach the p-n junction. If the differential of the potential is larger than the binding energy of the electron-hole pair and has a range larger than the Bohr radius of electron-hole pair, then the charge separation mechanism will be similar to traditional silicon solar cells. However, in the small-diameter limit, where quantum confinement effects are prominent, both the exciton binding energy and the potential drop will increase, and the p-n junction itself may have a dramatically different character. We present ab initio calculations based on the generalized gradient approximation (GGA) of silicon nanowires with 2-3 nm diameter in the [111] growth direction. A radial p-n junction was formed by symmetrically doping boron and phosphorous at the same vertical level along the axis of the nanowire. The competition between the slope and character of the radial electronic potential and the exciton binding energy will presented in the context of a charge separation mechanism.

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

Science.gov (United States)

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

2016-12-01

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

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....

Silicon nanowire arrays as learning chemical vapour classifiers

International Nuclear Information System (INIS)

Niskanen, A O; Colli, A; White, R; Li, H W; Spigone, E; Kivioja, J M

2011-01-01

Nanowire field-effect transistors are a promising class of devices for various sensing applications. Apart from detecting individual chemical or biological analytes, it is especially interesting to use multiple selective sensors to look at their collective response in order to perform classification into predetermined categories. We show that non-functionalised silicon nanowire arrays can be used to robustly classify different chemical vapours using simple statistical machine learning methods. We were able to distinguish between acetone, ethanol and water with 100% accuracy while methanol, ethanol and 2-propanol were classified with 96% accuracy in ambient conditions.

David Adler Lectureship Award Talk: III-V Semiconductor Nanowires on Silicon for Future Devices

Science.gov (United States)

Riel, Heike

Bottom-up grown nanowires are very attractive materials for direct integration of III-V semiconductors on silicon thus opening up new possibilities for the design and fabrication of nanoscale devices for electronic, optoelectronic as well as quantum information applications. Template-Assisted Selective Epitaxy (TASE) allows the well-defined and monolithic integration of complex III-V nanostructures and devices on silicon. Achieving atomically abrupt heterointerfaces, high crystal quality and control of dimension down to 1D nanowires enabled the demonstration of FETs and tunnel devices based on In(Ga)As and GaSb. Furthermore, the strong influence of strain on nanowires as well as results on quantum transport studies of InAs nanowires with well-defined geometry will be presented.

Creating New VLS Silicon Nanowire Contact Geometries by Controlling Catalyst Migration

DEFF Research Database (Denmark)

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

2015-01-01

The formation of self-assembled contacts between vapor-liquid-solid grown silicon nanowires and flat silicon surfaces was imaged in situ using electron microscopy. By measuring the structural evolution of the contact formation process, we demonstrate how different contact geometries are created b...

Angle-resolved diffraction grating biosensor based on porous silicon

Energy Technology Data Exchange (ETDEWEB)

Lv, Changwu; Li, Peng [School of Physical Science and Technology, Xinjiang University, Urumqi 830046 (China); Jia, Zhenhong, E-mail: jzhh@xju.edu.cn; Liu, Yajun; Mo, Jiaqing; Lv, Xiaoyi [College of Information Science and Engineering, Xinjiang University, Urumqi 830046 (China)

2016-03-07

In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

Selective etching of n-type silicon in pn junction structure in hydrofluoric acid and its application in silicon nanowire fabrication

International Nuclear Information System (INIS)

Wang Huiquan; Jin Zhonghe; Zheng Yangming; Ma Huilian; Wang Yuelin; Li Tie

2008-01-01

Boron is selectively implanted on the surface of an n-type silicon wafer to form a p-type area surrounded by an n-type area. The wafer is then put into a buffered oxide etch solution. It is found that the n-type area can be selectively etched without illumination, with an etching rate lower than 1 nm min -1 , while the p-type area can be selectively etched under illumination with a much higher etching rate. The possible mechanism of the etching phenomenon is discussed. A simple fabrication process of silicon nanowires is proposed according to the above phenomenon. In this process only traditional micro-electromechanical system technology is used. Dimensions of the fabricated nanowire can be controlled well. A 50 nm wide and 50 nm thick silicon nanowire has been formed using this method

Silicon Nanowire Fabrication Using Edge and Corner Lithography

NARCIS (Netherlands)

Yagubizade, H.; Berenschot, Johan W.; Jansen, Henricus V.; Elwenspoek, Michael Curt; Tas, Niels Roelof

2010-01-01

This paper presents a wafer scale fabrication method of single-crystalline silicon nanowires (SiNWs) bound by <111> planes using a combination of edge and corner lithography. These are methods of unconventional nanolithography for wafer scale nano-patterning which determine the size of nano-features

Ultra-low reflection porous silicon nanowires for solar cell applications

KAUST Repository

Najar, Adel

2012-01-01

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

Nanofabrication of Arrays of Silicon Field Emitters with Vertical Silicon Nanowire Current Limiters and Self-Aligned Gates

Science.gov (United States)

2016-08-19

limiters, MEMS, NEMS, field emission, cold cathodes (Some figures may appear in colour only in the online journal) 1. Introduction Dense arrays of silicon... attention has been given to densely packed, highly ordered, top-down fabricated, single crystal vertical silicon nanowire devices that are embedded

Porous silicon biosensor for detection of variable domain of heavy-chain of HCAb antibody

Science.gov (United States)

Zhang, Hong-yan; Lü, Xiao-yi; Jia, Zhen-hong; Li, Jiang-wei; Zhang, Fu-chun

2012-03-01

In this paper, we produce porous silicon (PSi) by electrochemical etching, and it is the first time to evaluate the performance of label-free porous silicon biosensor for detection of variable domain of heavy chain of heavy-chain antibody (VHH). The binding of hen egg white lysozyme (HEWL) and VHH causes a red shift in the reflection spectrum of the biosensor. The red shift is proportional to the VHH concentration in the range from 14 g·ml-1 to 30 g·ml-1 with a detection limit of 0.648 ng·ml-1. The research is useful for the development of label-free biosensor applied in the rapid and sensitive determination of small molecules.

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

International Nuclear Information System (INIS)

He Ying; Wang Junan; Pei Changlong; Song Jizhong; Zhu Di; Chen Jie

2010-01-01

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

Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

KAUST Repository

Ruffo, Riccardo; Hong, Seung Sae; Chan, Candace K.; Huggins, Robert A.; Cui, Yi

2009-01-01

The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured

Modeling of Temperature-Dependent Noise in Silicon Nanowire FETs including Self-Heating Effects

Directory of Open Access Journals (Sweden)

P. Anandan

2014-01-01

Full Text Available Silicon nanowires are leading the CMOS era towards the downsizing limit and its nature will be effectively suppress the short channel effects. Accurate modeling of thermal noise in nanowires is crucial for RF applications of nano-CMOS emerging technologies. In this work, a perfect temperature-dependent model for silicon nanowires including the self-heating effects has been derived and its effects on device parameters have been observed. The power spectral density as a function of thermal resistance shows significant improvement as the channel length decreases. The effects of thermal noise including self-heating of the device are explored. Moreover, significant reduction in noise with respect to channel thermal resistance, gate length, and biasing is analyzed.

Imaging, structural, and chemical analysis of silicon nanowires

International Nuclear Information System (INIS)

Barsotti, R.J. Jr.; Fischer, J.E.; Lee, C.H.; Mahmood, J.; Adu, C.K.W.; Eklund, P.C.

2002-01-01

Laser ablation has been used to grow silicon nanowires with an average silicon crystal core diameter of 6.7 nm±2.9 nm surrounded by an amorphous SiO x sheath of 1-2 nm, the smallest silicon wires reported in the literature. Imaging, chemical, and structural analysis of these wires are reported. Due to the growth temperature and the presence of calcium impurities and trace oxygen, two distinct types of wires are found. They appear to grow by two different processes. One requires a metal catalyst, the other is catalyzed by oxygen. Suggestions for controlled synthesis based on these growth mechanisms are made

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

Science.gov (United States)

Pan, Hui

2014-01-01

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

Nanostructured silicon-based biosensors for the selective identification of analytes of social interest

International Nuclear Information System (INIS)

D'Auria, Sabato; Champdore, Marcella de; Aurilia, Vincenzo; Parracino, Antonietta; Staiano, Maria; Vitale, Annalisa; Rossi, Mose; Rea, Ilaria; Rotiroti, Lucia; Rossi, Andrea M; Borini, Stefano; Rendina, Ivo; Stefano, Luca De

2006-01-01

Small analytes such as glucose, L-glutamine (Gln), and ammonium nitrate are detected by means of optical biosensors based on a very common nanostructured material, porous silicon (PSi). Specific recognition elements, such as protein receptors and enzymes, were immobilized on hydrogenated PSi wafers and used as probes in optical sensing systems. The binding events were optically transduced as wavelength shifts of the porous silicon reflectivity spectrum or were monitored via changes of the fluorescence emission. The biosensors described in this article suggest a general approach for the development of new sensing systems for a wide range of analytes of high social interest

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.

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.

Silicon nanowires as field-effect transducers for biosensor development: A review

Energy Technology Data Exchange (ETDEWEB)

Noor, M. Omair; Krull, Ulrich J., E-mail: ulrich.krull@utoronto.ca

2014-05-01

Highlights: • Nanoscale field-effect transducers interrogate surface charge by conductivity changes. • The nanometer dimensions of SiNWs facilitate sensitive detection of biomolecules. • SiNWs can be fabricated by bottom–up or top–down approaches. • Device parameters and solution-phase conditions strongly influence analytical performance. - Abstract: The unique electronic properties and miniaturized dimensions of silicon nanowires (SiNWs) are attractive for label-free, real-time and sensitive detection of biomolecules. Sensors based on SiNWs operate as field effect transistors (FETs) and can be fabricated either by top–down or bottom–up approaches. Advances in fabrication methods have allowed for the control of physicochemical and electronic properties of SiNWs, providing opportunity for interfacing of SiNW-FET probes with intracellular environments. The Debye screening length is an important consideration that determines the performance and detection limits of SiNW-FET sensors, especially at physiologically relevant conditions of ionic strength (>100 mM). In this review, we discuss the construction and application of SiNW-FET sensors for detection of ions, nucleic acids and protein markers. Advantages and disadvantages of the top–down and bottom–up approaches for synthesis of SiNWs are discussed. An overview of various methods for surface functionalization of SiNWs for immobilization of selective chemistry is provided in the context of impact on the analytical performance of SiNW-FET sensors. In addition to in vitro examples, an overview of the progress of use of SiNW-FET sensors for ex vivo studies is also presented. This review concludes with a discussion of the future prospects of SiNW-FET sensors.

Silicon nanowires as field-effect transducers for biosensor development: A review

International Nuclear Information System (INIS)

Noor, M. Omair; Krull, Ulrich J.

2014-01-01

Highlights: • Nanoscale field-effect transducers interrogate surface charge by conductivity changes. • The nanometer dimensions of SiNWs facilitate sensitive detection of biomolecules. • SiNWs can be fabricated by bottom–up or top–down approaches. • Device parameters and solution-phase conditions strongly influence analytical performance. - Abstract: The unique electronic properties and miniaturized dimensions of silicon nanowires (SiNWs) are attractive for label-free, real-time and sensitive detection of biomolecules. Sensors based on SiNWs operate as field effect transistors (FETs) and can be fabricated either by top–down or bottom–up approaches. Advances in fabrication methods have allowed for the control of physicochemical and electronic properties of SiNWs, providing opportunity for interfacing of SiNW-FET probes with intracellular environments. The Debye screening length is an important consideration that determines the performance and detection limits of SiNW-FET sensors, especially at physiologically relevant conditions of ionic strength (>100 mM). In this review, we discuss the construction and application of SiNW-FET sensors for detection of ions, nucleic acids and protein markers. Advantages and disadvantages of the top–down and bottom–up approaches for synthesis of SiNWs are discussed. An overview of various methods for surface functionalization of SiNWs for immobilization of selective chemistry is provided in the context of impact on the analytical performance of SiNW-FET sensors. In addition to in vitro examples, an overview of the progress of use of SiNW-FET sensors for ex vivo studies is also presented. This review concludes with a discussion of the future prospects of SiNW-FET sensors

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

DEFF Research Database (Denmark)

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

2009-01-01

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

Silicon Nanowire Field-effect Chemical Sensor

OpenAIRE

Chen, S.

2011-01-01

This thesis describes the work that has been done on the project “Design and optimization of silicon nanowire for chemical sensing‿, including Si-NW fabrication, electrical/electrochemical modeling, the application as ISFET, and the build-up of Si- NW/LOC system for automatic sample delivery. A novel top-down fabrication technique was presented for single-crystal Si-NW fabrication realized with conventional microfabrication technique. High quality triangular Si-NWs were made with high wafer-s...

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.

Label-free silicon photonic biosensor system with integrated detector array

Science.gov (United States)

Yan, Rongjin; Mestas, Santano P.; Yuan, Guangwei; Safaisini, Rashid; Dandy, David S.

2010-01-01

An integrated, inexpensive, label-free photonic waveguide biosensor system with multi-analyte capability has been implemented on a silicon photonics integrated circuit from a commercial CMOS line and tested with nanofilms. The local evanescent array coupled (LEAC) biosensor is based on a new physical phenomenon that is fundamentally different from the mechanisms of other evanescent field sensors. Increased local refractive index at the waveguide’s upper surface due to the formation of a biological nanofilm causes local modulation of the evanescent field coupled into an array of photodetectors buried under the waveguide. The planar optical waveguide biosensor system exhibits sensitivity of 20%/nm photocurrent modulation in response to adsorbed bovine serum albumin (BSA) layers less than 3 nm thick. In addition to response to BSA, an experiment with patterned photoresist as well as beam propagation method simulations support the evanescent field shift principle. The sensing mechanism enables the integration of all optical and electronic components for a multi-analyte biosensor system on a chip. PMID:19606292

Label-free silicon photonic biosensor system with integrated detector array.

Science.gov (United States)

Yan, Rongjin; Mestas, Santano P; Yuan, Guangwei; Safaisini, Rashid; Dandy, David S; Lear, Kevin L

2009-08-07

An integrated, inexpensive, label-free photonic waveguide biosensor system with multi-analyte capability has been implemented on a silicon photonics integrated circuit from a commercial CMOS line and tested with nanofilms. The local evanescent array coupled (LEAC) biosensor is based on a new physical phenomenon that is fundamentally different from the mechanisms of other evanescent field sensors. Increased local refractive index at the waveguide's upper surface due to the formation of a biological nanofilm causes local modulation of the evanescent field coupled into an array of photodetectors buried under the waveguide. The planar optical waveguide biosensor system exhibits sensitivity of 20%/nm photocurrent modulation in response to adsorbed bovine serum albumin (BSA) layers less than 3 nm thick. In addition to response to BSA, an experiment with patterned photoresist as well as beam propagation method simulations support the evanescent field shift principle. The sensing mechanism enables the integration of all optical and electronic components for a multi-analyte biosensor system on a chip.

Rationally designed porous silicon as platform for optical biosensors

International Nuclear Information System (INIS)

Priano, G.; Acquaroli, L.N.; Lasave, L.C.; Battaglini, F.; Arce, R.D.; Koropecki, R.R.

2012-01-01

Optical porous silicon multilayer structures are able to work as sensitive chemical sensors or biosensors based in their optical response. An algorithm to simulate the optical response of these multilayers was developed, considering the optical properties of the individual layers. The algorithm allows designing and customizing the porous silicon structures according to a given application. The results obtained by the simulation were experimentally verified; for this purpose different photonic structures were prepared, such as Bragg reflectors and microcavities. Some of these structures have been derivatized by the introduction of aminosilane groups on the porous silicon surface. The algorithm also permits to simulate the effects produced by a non uniform derivatization of the multilayer. - Highlights: ► Mesoporous silicon structure ► Functionalization of mesoporous silicon as sensors ► Design of the one-dimensional photonic crystal ► Simulation of non-uniformity in covering the sensor structure

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

Indian Academy of Sciences (India)

Silicon carbide (SiC) nanowire has been fabricated by hot filament chemical vapour .... −5. Torr by mechanical and dif- fusion vacuum pumps, then high purity H2 gas was fed into it. ... to standard PDF card numbers of 01-074-2307 and 01-.

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

DEFF Research Database (Denmark)

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

2007-01-01

We combine the ideas of scaling theory and universal conductance fluctuations with density-functional theory to analyze the conductance properties of doped silicon nanowires. Specifically, we study the crossover from ballistic to diffusive transport in boron or phosphorus doped Si nanowires...

Epitaxial III-V nanowires on silicon for vertical devices

NARCIS (Netherlands)

Bakkers, E.P.A.M.; Borgström, M.T.; Einden, Van Den W.; Weert, van M.H.M.; Helman, A.; Verheijen, M.A.

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the Vapor-Liquid-Solid (VLS) mechanism with laser ablation as well as metal organic vapor phase epitaxy. The VLS growth enables the fabrication of complex axial and radial

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

International Nuclear Information System (INIS)

Bai, Fan; Li, Meicheng; Song, Dandan; Yu, Hang; Jiang, Bing; Li, Yingfeng

2012-01-01

One-step synthesis of lightly doped porous silicon nanowire arrays was achieved by etching the silicon wafer in HF/AgNO 3 /H 2 O 2 solution at room temperature. The lightly doped porous silicon nanowires (pNWs) have circular nanopores on the sidewall, which can emit strong green fluorescence. The surface morphologies of these nanowires could be controlled by simply adjusting the concentration of H 2 O 2 , which influences the distribution of silver nanoparticles (Ag NPs) along the nanowire axis. A mechanism based on Ag NPs-induced lateral etching of nanowires was proposed to explain the formation of pNWs. The controllable and widely applicable synthesis of pNWs will open their potential application to nanoscale photoluminescence devices. - Graphical abstract: The one-step synthesis of porous silicon nanowire arrays is achieved by chemical etching of the lightly doped p-type Si (100) wafer at room temperature. These nanowires exhibit strong green photoluminescence. SEM, TEM, HRTEM and photoluminescence images of pNWs. The scale bars of SEM, TEM HRTEM and photoluminescence are 10 μm, 20 nm, 10 nm, and 1 μm, respectively. Highlights: ► Simple one-step synthesis of lightly doped porous silicon nanowire arrays is achieved at RT. ► Etching process and mechanism are illustrated with etching model from a novel standpoint. ► As-prepared porous silicon nanowire emits strong green fluorescence, proving unique property.

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

KAUST Repository

Cui, Li-Feng

2009-01-14

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

High-performance lithium battery anodes using silicon nanowires.

Science.gov (United States)

Chan, Candace K; Peng, Hailin; Liu, Gao; McIlwrath, Kevin; Zhang, Xiao Feng; Huggins, Robert A; Cui, Yi

2008-01-01

There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

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

KAUST Repository

Frost, Thomas; Jahangir, Shafat; Stark, Ethan; Deshpande, Saniya; Hazari, Arnab Shashi; Zhao, Chao; Ooi, Boon S.; Bhattacharya, Pallab K.

2014-01-01

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

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

KAUST Repository

Frost, Thomas

2014-08-13

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

Strain and thermal conductivity in ultrathin suspended silicon nanowires

Science.gov (United States)

Fan, Daniel; Sigg, Hans; Spolenak, Ralph; Ekinci, Yasin

2017-09-01

We report on the uniaxial strain and thermal conductivity of well-ordered, suspended silicon nanowire arrays between 10 to 20 nm width and 22 nm half-pitch, fabricated by extreme-ultraviolet (UV) interference lithography. Laser-power-dependent Raman spectroscopy showed that nanowires connected monolithically to the bulk had a consistent strain of ˜0.1 % , whereas nanowires clamped by metal exhibited variability and high strain of up to 2.3%, having implications in strain engineering of nanowires. The thermal conductivity at room temperature was measured to be ˜1 W /m K for smooth nanowires and ˜0.1 W /m K for rougher ones, similar to results by other investigators. We found no modification of the bulk properties in terms of intrinsic scattering, and therefore, the decrease in thermal conductivity is mainly due to boundary scattering. Different types of surface roughness, such as constrictions and line-edge roughness, may play roles in the scattering of phonons of different wavelengths. Such low thermal conductivities would allow for very efficient thermal energy harvesting, approaching and passing values achieved by state-of-the-art thermoelectric materials.

Rationally designed porous silicon as platform for optical biosensors

Energy Technology Data Exchange (ETDEWEB)

Priano, G. [INQUIMAE, DQIAyQF, FCEN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 2 (C1428EHA) Buenos Aires (Argentina); Acquaroli, L.N.; Lasave, L.C. [Instituto De Desarrollo Tecnologico Para La Industria Quimica, UNL, CONICET, Gueemes 3450 (S3000GLN) Santa Fe (Argentina); Battaglini, F. [INQUIMAE, DQIAyQF, FCEN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 2 (C1428EHA) Buenos Aires (Argentina); Arce, R.D., E-mail: rarce@intec.unl.edu.ar [Instituto De Desarrollo Tecnologico Para La Industria Quimica, UNL, CONICET, Gueemes 3450 (S3000GLN) Santa Fe (Argentina); Departamento De Materiales, Facultad De Ingenieria Quimica, UNL, Santiago del Estero 2829 (S3000) Santa Fe (Argentina); Koropecki, R.R. [Instituto De Desarrollo Tecnologico Para La Industria Quimica, UNL, CONICET, Gueemes 3450 (S3000GLN) Santa Fe (Argentina); Departamento De Materiales, Facultad De Ingenieria Quimica, UNL, Santiago del Estero 2829 (S3000) Santa Fe (Argentina)

2012-08-01

Optical porous silicon multilayer structures are able to work as sensitive chemical sensors or biosensors based in their optical response. An algorithm to simulate the optical response of these multilayers was developed, considering the optical properties of the individual layers. The algorithm allows designing and customizing the porous silicon structures according to a given application. The results obtained by the simulation were experimentally verified; for this purpose different photonic structures were prepared, such as Bragg reflectors and microcavities. Some of these structures have been derivatized by the introduction of aminosilane groups on the porous silicon surface. The algorithm also permits to simulate the effects produced by a non uniform derivatization of the multilayer. - Highlights: Black-Right-Pointing-Pointer Mesoporous silicon structure Black-Right-Pointing-Pointer Functionalization of mesoporous silicon as sensors Black-Right-Pointing-Pointer Design of the one-dimensional photonic crystal Black-Right-Pointing-Pointer Simulation of non-uniformity in covering the sensor structure.

Synthesis and investigation of silicon carbide nanowires by HFCVD

Indian Academy of Sciences (India)

We found that increasing substrate temperature increases silicon and oxygen doping amount. We also found that electrical resistivity and surface roughness increased by increasing substrate temperature. This study showed that SiC nanowires with high density grew on the free catalyst glass substrate, and the alignment of ...

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

Energy Technology Data Exchange (ETDEWEB)

Clément, N., E-mail: nicolas.clement@iemn.univ-lille1.fr, E-mail: guilhem.larrieu@laas.fr; Han, X. L. [Institute of Electronics, Microelectronics and Nanotechnology, CNRS, Avenue Poincaré, 59652 Villeneuve d' Ascq (France); Larrieu, G., E-mail: nicolas.clement@iemn.univ-lille1.fr, E-mail: guilhem.larrieu@laas.fr [Laboratory for Analysis and Architecture of Systems (LAAS), CNRS, Universite de Toulouse, 7 Avenue Colonel Roche, 31077 Toulouse (France)

2013-12-23

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

Layered structure in core–shell silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-15

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

Influence of surface pre-treatment on the electronic levels in silicon MaWCE nanowires.

Science.gov (United States)

Venturi, Giulia; Castaldini, Antonio; Schleusener, Alexander; Sivakov, Vladimir; Cavallini, Anna

2015-05-15

Deep level transient spectroscopy (DLTS) was performed on n-doped silicon nanowires grown by metal-assisted wet chemical etching (MaWCE) with gold as the catalyst in order to investigate the energetic scheme inside the bandgap. To observe the possible dependence of the level scheme on the processing temperature, DLTS measurements were performed on the nanowires grown on a non-treated Au/Si surface and on a thermally pre-treated Au/Si surface. A noticeable modification of the configuration of the energy levels was observed, induced by the annealing process. Based on our results on these MaWCE nanowires and on literature data about deep levels in bulk silicon, some hypotheses were advanced regarding the identification of the defects responsible of the energy levels revealed.

Effective antireflection properties of porous silicon nanowires for photovoltaic applications

KAUST Repository

Najar, Adel; Al-Jabr, Ahmad; Alsunaidi, Mohammad; Anjum, Dalaver H.; Ng, Tien Khee; Ooi, Boon S.; Ben Slimane, Ahmed; Sougrat, Rachid

2013-01-01

Porous silicon nanowires (PSiNWs) have been prepared by metal-assisted chemical etching method on the n-Si substrate. The presence of nano-pores with pore size ranging between 10-50nm in SiNWs was confirmed by electron tomography (ET

Potential of silicon nanowires structures as nanoscale piezoresistors in mechanical sensors

International Nuclear Information System (INIS)

Messina, M; Njuguna, J

2012-01-01

This paper presents the design of a single square millimeter 3-axial accelerometer for bio-mechanics measurements that exploit the potential of silicon nanowires structures as nanoscale piezoresistors. The main requirements of this application are miniaturization and high measurement accuracy. Nanowires as nanoscale piezoresistive devices have been chosen as sensing element, due to their high sensitivity and miniaturization achievable. By exploiting the electro-mechanical features of nanowires as nanoscale piezoresistors, the nominal sensor sensitivity is overall boosted by more than 30 times. This approach allows significant higher accuracy and resolution with smaller sensing element in comparison with conventional devices without the need of signal amplification.

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

DEFF Research Database (Denmark)

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

2014-01-01

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

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

DEFF Research Database (Denmark)

Hu, Hao; Ji, Hua; Galili, Michael

2011-01-01

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

Crosstalk analysis of silicon-on-insulator nanowire-arrayed waveguide grating

International Nuclear Information System (INIS)

Li Kai-Li; An Jun-Ming; Zhang Jia-Shun; Wang Yue; Wang Liang-Liang; Li Jian-Guang; Wu Yuan-Da; Yin Xiao-Jie; Hu Xiong-Wei

2016-01-01

The factors influencing the crosstalk of silicon-on-insulator (SOI) nanowire arrayed waveguide grating (AWG) are analyzed using the transfer function method. The analysis shows that wider and thicker arrayed waveguides, outsider fracture of arrayed waveguide, and larger channel space, could mitigate the deterioration of crosstalk. The SOI nanowire AWGs with different arrayed waveguide widths are fabricated by using deep ultraviolet lithography (DUV) and inductively coupled plasma etching (ICP) technology. The measurement results show that the crosstalk performance is improved by about 7 dB through adopting 800 nm arrayed waveguide width. (paper)

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....

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

Synthesis and properties of silicon nanowire devices

Science.gov (United States)

Byon, Kumhyo

Silicon nanowire (SiNW) is a very attractive one-dimensional material for future nanoelectronic applications. Reliable control of key field effect transistor (FET) parameters such as conductance, mobility, threshold voltage and on/off ratio is crucial to the applications of SiNW to working logic devices and integrated circuits. In this thesis, we fabricated silicon nanowire field effect transistors (SiNW FETs) and studied the dependence of their electrical transport properties upon various parameters including SiNW growth conditions, post-growth doping, and contact annealing. From these studies, we found how different processes control important FET characteristics. Key accomplishments of this thesis include p-channel enhancement mode FETs, n-channel FETs by post-growth vapor doping and high performance ambipolar devices. In the first part of this work, single crystalline SiNWs were synthesized by thermal evaporation without gold catalysts. FETs were fabricated using both as-grown SiNWs and post-growth n-doped SiNWs. FET from p-type source materials behaves as a p-channel enhancement mode FET which is predominant in logic devices due to its fast operation and low power consumption. Using bismuth vapor, the as-grown SiNWs were doped into n-type materials. The majority carriers in SiNWs can therefore be controlled by proper choice of the vapor phase dopant species. Post-growth doping using vapor phase is applicable to other nanowire systems. In the second part, high performance ambipolar FETs were fabricated. A two step annealing process was used to control the Schottky barrier between SiNW and metal contacts in order to enhance device performance. Initial p-channel SiNW FETs were converted into ambipolar SiNW FETs after contact annealing. Furthermore, significant increases in both on/off ratio and channel mobilities were achieved after contact annealing. Promising device structures to implement ambipolar devices into large scale integrated circuits were proposed

Ultra-low reflection porous silicon nanowires for solar cell applications

KAUST Repository

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

2012-01-01

% reflectivity of the starting silicon wafer drops to 0.1% recorded for more than 10 μm long PSiNWs. Models based on cone shape of nanowires located in a circular and rectangular bases were used to calculate the reflectance employing the Transfert Matrix

Localized synthesis, assembly and integration of silicon nanowires

Science.gov (United States)

Englander, Ongi

Localized synthesis, assembly and integration of one-dimensional silicon nanowires with MEMS structures is demonstrated and characterized in terms of local synthesis processes, electric-field assisted self-assembly, and a proof-of-concept nanoelectromechanical system (HEMS) demonstration. Emphasis is placed on the ease of integration, process control strategies, characterization techniques and the pursuit of integrated devices. A top-down followed by a bottom-up integration approach is utilized. Simple MEMS heater structures are utilized as the microscale platforms for the localized, bottom-up synthesis of one-dimensional nanostructures. Localized heating confines the high temperature region permitting only localized nanostructure synthesis and allowing the surroundings to remain at room temperature thus enabling CMOS compatible post-processing. The vapor-liquid-solid (VLS) process in the presence of a catalytic nanoparticle, a vapor phase reactant, and a specific temperature environment is successfully employed locally. Experimentally, a 5nm thick gold-palladium layer is used as the catalyst while silane is the vapor phase reactant. The current-voltage behavior of the MEMS structures can be correlated to the approximate temperature range required for the VLS reaction to take place. Silicon nanowires averaging 45nm in diameter and up to 29mum in length synthesized at growth rates of up to 1.5mum/min result. By placing two MEMS structures in close proximity, 4--10mum apart, localized silicon nanowire growth can be used to link together MEMS structures to yield a two-terminal, self-assembled micro-to-nano system. Here, one MEMS structure is designated as the hot growth structure while a nearby structure is designated as the cold secondary structure, whose role is to provide a natural stopping point for the VLS reaction. The application of a localized electric-field, 5 to 13V/mum in strength, during the synthesis process, has been shown to improve nanowire

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.

Electrical characteristics of silicon percolating nanonet-based field effect transistors in the presence of dispersion

Science.gov (United States)

Cazimajou, T.; Legallais, M.; Mouis, M.; Ternon, C.; Salem, B.; Ghibaudo, G.

2018-05-01

We studied the current-voltage characteristics of percolating networks of silicon nanowires (nanonets), operated in back-gated transistor mode, for future use as gas or biosensors. These devices featured P-type field-effect characteristics. It was found that a Lambert W function-based compact model could be used for parameter extraction of electrical parameters such as apparent low field mobility, threshold voltage and subthreshold slope ideality factor. Their variation with channel length and nanowire density was related to the change of conduction regime from direct source/drain connection by parallel nanowires to percolating channels. Experimental results could be related in part to an influence of the threshold voltage dispersion of individual nanowires.

Preparation of silicon carbide nanowires via a rapid heating process

International Nuclear Information System (INIS)

Li Xintong; Chen Xiaohong; Song Huaihe

2011-01-01

Silicon carbide (SiC) nanowires were fabricated in a large quantity by a rapid heating carbothermal reduction of a novel resorcinol-formaldehyde (RF)/SiO 2 hybrid aerogel in this study. SiC nanowires were grown at 1500 deg. C for 2 h in an argon atmosphere without any catalyst via vapor-solid (V-S) process. The β-SiC nanowires were characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM) equipped with energy dispersive X-ray (EDX) facility, Fourier transformed infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The analysis results show that the aspect ratio of the SiC nanowires via the rapid heating process is much larger than that of the sample produced via gradual heating process. The SiC nanowires are single crystalline β-SiC phase with diameters of about 20-80 nm and lengths of about several tens of micrometers, growing along the [1 1 1] direction with a fringe spacing of 0.25 nm. The role of the interpenetrating network of RF/SiO 2 hybrid aerogel in the carbothermal reduction was discussed and the possible growth mechanism of the nanowires is analyzed.

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

International Nuclear Information System (INIS)

So, Hongyun; Pisano, Albert P.; Cheng, Jim C.

2013-01-01

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

Structural and photoluminescence investigation on the hot-wire assisted plasma enhanced chemical vapor deposition growth silicon nanowires

International Nuclear Information System (INIS)

Chong, Su Kong; Goh, Boon Tong; Wong, Yuen-Yee; Nguyen, Hong-Quan; Do, Hien; Ahmad, Ishaq; Aspanut, Zarina; Muhamad, Muhamad Rasat; Dee, Chang Fu; Rahman, Saadah Abdul

2012-01-01

High density of silicon nanowires (SiNWs) were synthesized by a hot-wire assisted plasma enhanced chemical vapor deposition technique. The structural and optical properties of the as-grown SiNWs prepared at different rf power of 40 and 80 W were analyzed in this study. The SiNWs prepared at rf power of 40 W exhibited highly crystalline structure with a high crystal volume fraction, X C of ∼82% and are surrounded by a thin layer of SiO x . The NWs show high absorption in the high energy region (E>1.8 eV) and strong photoluminescence at 1.73 to 2.05 eV (red–orange region) with a weak shoulder at 1.65 to 1.73 eV (near IR region). An increase in rf power to 80 W reduced the X C to ∼65% and led to the formation of nanocrystalline Si structures with a crystallite size of <4 nm within the SiNWs. These NWs are covered by a mixture of uncatalyzed amorphous Si layer. The SiNWs prepared at 80 W exhibited a high optical absorption ability above 99% in the broadband range between 220 and ∼1500 nm and red emission between 1.65 and 1.95 eV. The interesting light absorption and photoluminescence properties from both SiNWs are discussed in the text. - Highlights: ► Growth of random oriented silicon nanowires using hot-wire assisted plasma enhanced chemical vapor deposition. ► Increase in rf power reduces the crystallinity of silicon nanowires. ► High density and nanocrystalline structure in silicon nanowires significant enhance the near IR light absorption. ► Oxide defects and silicon nanocrystallites in silicon nanowires reveal photoluminescence in red–orange and red regions.

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

Science.gov (United States)

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

2016-01-01

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

Ion-step method for surface potential sensing of silicon nanowires

NARCIS (Netherlands)

Chen, S.; van Nieuwkasteele, Jan William; van den Berg, Albert; Eijkel, Jan C.T.

2016-01-01

This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected.

A comprehensive study of thermoelectric and transport properties of β-silicon carbide nanowires

Energy Technology Data Exchange (ETDEWEB)

Valentín, L. A.; Betancourt, J.; Fonseca, L. F., E-mail: luis.fonseca@upr.edu [Department of Physics University of Puerto Rico, Rio Piedras (Puerto Rico); Pettes, M. T.; Shi, L. [Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712 (United States); Soszyński, M.; Huczko, A. [Department of Chemistry, Warsaw University, Pasteur 1 Str., 02-093 Warsaw (Poland)

2013-11-14

The temperature dependence of the Seebeck coefficient, the electrical and thermal conductivities of individual β-silicon carbide nanowires produced by combustion in a calorimetric bomb were studied using a suspended micro-resistance thermometry device that allows four-point probe measurements to be conducted on each nanowire. Additionally, crystal structure and growth direction for each measured nanowire was directly obtained by transmission electron microscopy analysis. The Fermi level, the carrier concentration, and mobility of each nanostructure were determined using a combination of Seebeck coefficient and electrical conductivity measurements, energy band structure and transport theory calculations. The temperature dependence of the thermal and electrical conductivities of the nanowires was explained in terms of contributions from boundary, impurity, and defect scattering.

Hybridization assay of insect antifreezing protein gene by novel multilayered porous silicon nucleic acid biosensor.

Science.gov (United States)

Lv, Xiaoyi; Chen, Liangliang; Zhang, Hongyan; Mo, Jiaqing; Zhong, Furu; Lv, Changwu; Ma, Ji; Jia, Zhenhong

2013-01-15

A fabrication of a novel simple porous silicon polybasic photonic crystal with symmetrical structure has been reported as a nucleic acid biosensor for detecting antifreeze protein gene in insects (Microdera puntipennis dzhungarica), which would be helpful in the development of some new transgenic plants with tolerance of freezing stress. Compared to various porous silicon-based photonic configurations, porous silicon polytype layered structure is quite easy to prepare and shows more stability; moreover, polybasic photonic crystals with symmetrical structure exhibit interesting optical properties with a sharp resonance in the reflectance spectrum, giving a higher Q factor which causes higher sensitivity for sensing performance. In this experiment, DNA oligonucleotides were immobilized into the porous silicon pores using a standard crosslink chemistry method. The porous silicon polybasic symmetrical structure sensor possesses high specificity in performing controlled experiments with non-complementary DNA. The detection limit was found to be 21.3nM for DNA oligonucleotides. The fabricated multilayered porous silicon-based DNA biosensor has potential commercial applications in clinical chemistry for determination of an antifreeze protein gene or other genes. Copyright © 2012 Elsevier B.V. All rights reserved.

High-Sensitivity Temperature-Independent Silicon Photonic Microfluidic Biosensors

Science.gov (United States)

Kim, Kangbaek

Optical biosensors that can precisely quantify the presence of specific molecular species in real time without the need for labeling have seen increased use in the drug discovery industry and molecular biology in general. Of the many possible optical biosensors, the TM mode Si biosensor is shown to be very attractive in the sensing application because of large field amplitude on the surface and cost effective CMOS VLSI fabrication. Noise is the most fundamental factor that limits the performance of sensors in development of high-sensitivity biosensors, and noise reduction techniques require precise studies and analysis. One such example stems from thermal fluctuations. Generally SOI biosensors are vulnerable to ambient temperature fluctuations because of large thermo-optic coefficient of silicon (˜2x10 -4 RIU/K), typically requiring another reference ring and readout sequence to compensate temperature induced noise. To address this problem, we designed sensors with a novel TM-mode shallow-ridge waveguide that provides both large surface amplitude for bulk and surface sensing. With proper design, this also provides large optical confinement in the aqueous cladding that renders the device athermal using the negative thermo-optic coefficient of water (~ --1x10-4RIU/K), demonstrating cancellation of thermo-optic effects for aqueous solution operation near 300K. Additional limitations resulting from mechanical actuator fluctuations, stability of tunable lasers, and large 1/f noise of lasers and sensor electronics can limit biosensor performance. Here we also present a simple harmonic feedback readout technique that obviates the need for spectrometers and tunable lasers. This feedback technique reduces the impact of 1/f noise to enable high-sensitivity, and a DSP lock-in with 256 kHz sampling rate can provide down to micros time scale monitoring for fast transitions in biomolecular concentration with potential for small volume and low cost. In this dissertation, a novel

Large-size, high-uniformity, random silver nanowire networks as transparent electrodes for crystalline silicon wafer solar cells.

Science.gov (United States)

Xie, Shouyi; Ouyang, Zi; Jia, Baohua; Gu, Min

2013-05-06

Metal nanowire networks are emerging as next generation transparent electrodes for photovoltaic devices. We demonstrate the application of random silver nanowire networks as the top electrode on crystalline silicon wafer solar cells. The dependence of transmittance and sheet resistance on the surface coverage is measured. Superior optical and electrical properties are observed due to the large-size, highly-uniform nature of these networks. When applying the nanowire networks on the solar cells with an optimized two-step annealing process, we achieved as large as 19% enhancement on the energy conversion efficiency. The detailed analysis reveals that the enhancement is mainly caused by the improved electrical properties of the solar cells due to the silver nanowire networks. Our result reveals that this technology is a promising alternative transparent electrode technology for crystalline silicon wafer solar cells.

Fluorinated alkyne-derived monolayers on oxide-free silicon nanowires via one-step hydrosilylation

International Nuclear Information System (INIS)

Nguyen Minh, Quyen; Pujari, Sidharam P.; Wang, Bin; Wang, Zhanhua; Haick, Hossam; Zuilhof, Han; Rijn, Cees J.M. van

2016-01-01

Highlights: • Oxide-free H-terminated silicon nanowires undergo efficient surface modification by reaction with fluorinated 1-alkynes (HC≡C−(CH 2 ) 6 C 8 H 17−x F x ; x = 0–17). • These surface-modified Si NWs are chemically stable under range of conditions (including acid, base). • The surface coating yields efficient electrical passivation as demonstrated by a near-zero electrochemical activity of the surface. - Abstract: Passivation of oxide-free silicon nanowires (Si NWs) by the formation of high-quality fluorinated 1-hexadecyne-derived monolayers with varying fluorine content has been investigated. Alkyl chain monolayers (C 16 H 30−x F x ) with a varying number of fluorine substituents (x = 0, 1, 3, 9, 17) were attached onto hydrogen-terminated silicon (Si−H) surfaces with an effective one-step hydrosilylation. This surface chemistry gives well-defined monolayers on nanowires that have a cylindrical core–shell structure, as characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and static contact angle (SCA) analysis. The monolayers were stable under acidic and basic conditions, as well as under extreme conditions (such as UV exposure), and provide excellent surface passivation, which opens up applications in the fields of field effect transistors, optoelectronics and especially for disease diagnosis.

Tunable electronic transport properties of silicon-fullerene-linked nanowires: Semiconductor, conducting wire, and tunnel diode

OpenAIRE

Nishio, Kengo; Ozaki, Taisuke; Morishita, Tetsuya; Mikami, Masuhiro

2010-01-01

We explore the possibility of controllable tuning of the electronic transport properties of silicon-fullerene-linked nanowires by encapsulating guest atoms into their cages. Our first-principles calculations demonstrate that the guest-free nanowires are semiconductors, and do not conduct electricity. The iodine or sodium doping improves the transport properties, and makes the nanowires metallic. In the junctions of I-doped and Na-doped NWs, the current travels through the boundary by quantum ...

Thermal conductivity engineering in width-modulated silicon nanowires and thermoelectric efficiency enhancement

Science.gov (United States)

Zianni, Xanthippi

2018-03-01

Width-modulated nanowires have been proposed as efficient thermoelectric materials. Here, the electron and phonon transport properties and the thermoelectric efficiency are discussed for dimensions above the quantum confinement regime. The thermal conductivity decreases dramatically in the presence of thin constrictions due to their ballistic thermal resistance. It shows a scaling behavior upon the width-modulation rate that allows for thermal conductivity engineering. The electron conductivity also decreases due to enhanced boundary scattering by the constrictions. The effect of boundary scattering is weaker for electrons than for phonons and the overall thermoelectric efficiency is enhanced. A ZT enhancement by a factor of 20-30 is predicted for width-modulated nanowires compared to bulk silicon. Our findings indicate that width-modulated nanostructures are promising for developing silicon nanostructures with high thermoelectric efficiency.

Effect of electroless etching parameters on the growth and reflection properties of silicon nanowires

International Nuclear Information System (INIS)

Ozdemir, Baris; Unalan, Husnu Emrah; Kulakci, Mustafa; Turan, Rasit

2011-01-01

Vertically aligned silicon nanowire (Si NW) arrays have been fabricated over large areas using an electroless etching (EE) method, which involves etching of silicon wafers in a silver nitrate and hydrofluoric acid based solution. A detailed parametric study determining the relationship between nanowire morphology and time, temperature, solution concentration and starting wafer characteristics (doping type, resistivity, crystallographic orientation) is presented. The as-fabricated Si NW arrays were analyzed by field emission scanning electron microscope (FE-SEM) and a linear dependency of nanowire length to both temperature and time was obtained and the change in the growth rate of Si NWs at increased etching durations was shown. Furthermore, the effects of EE parameters on the optical reflectivity of the Si NWs were investigated in this study. Reflectivity measurements show that the 42.8% reflectivity of the starting silicon wafer drops to 1.3%, recorded for 10 μm long Si NW arrays. The remarkable decrease in optical reflectivity indicates that Si NWs have a great potential to be utilized in radial or coaxial p-n heterojunction solar cells that could provide orthogonal photon absorption and enhanced carrier collection.

Effect of electroless etching parameters on the growth and reflection properties of silicon nanowires.

Science.gov (United States)

Ozdemir, Baris; Kulakci, Mustafa; Turan, Rasit; Unalan, Husnu Emrah

2011-04-15

Vertically aligned silicon nanowire (Si NW) arrays have been fabricated over large areas using an electroless etching (EE) method, which involves etching of silicon wafers in a silver nitrate and hydrofluoric acid based solution. A detailed parametric study determining the relationship between nanowire morphology and time, temperature, solution concentration and starting wafer characteristics (doping type, resistivity, crystallographic orientation) is presented. The as-fabricated Si NW arrays were analyzed by field emission scanning electron microscope (FE-SEM) and a linear dependency of nanowire length to both temperature and time was obtained and the change in the growth rate of Si NWs at increased etching durations was shown. Furthermore, the effects of EE parameters on the optical reflectivity of the Si NWs were investigated in this study. Reflectivity measurements show that the 42.8% reflectivity of the starting silicon wafer drops to 1.3%, recorded for 10 µm long Si NW arrays. The remarkable decrease in optical reflectivity indicates that Si NWs have a great potential to be utilized in radial or coaxial p-n heterojunction solar cells that could provide orthogonal photon absorption and enhanced carrier collection.

Effect of electroless etching parameters on the growth and reflection properties of silicon nanowires

Science.gov (United States)

Ozdemir, Baris; Kulakci, Mustafa; Turan, Rasit; Emrah Unalan, Husnu

2011-04-01

Vertically aligned silicon nanowire (Si NW) arrays have been fabricated over large areas using an electroless etching (EE) method, which involves etching of silicon wafers in a silver nitrate and hydrofluoric acid based solution. A detailed parametric study determining the relationship between nanowire morphology and time, temperature, solution concentration and starting wafer characteristics (doping type, resistivity, crystallographic orientation) is presented. The as-fabricated Si NW arrays were analyzed by field emission scanning electron microscope (FE-SEM) and a linear dependency of nanowire length to both temperature and time was obtained and the change in the growth rate of Si NWs at increased etching durations was shown. Furthermore, the effects of EE parameters on the optical reflectivity of the Si NWs were investigated in this study. Reflectivity measurements show that the 42.8% reflectivity of the starting silicon wafer drops to 1.3%, recorded for 10 µm long Si NW arrays. The remarkable decrease in optical reflectivity indicates that Si NWs have a great potential to be utilized in radial or coaxial p-n heterojunction solar cells that could provide orthogonal photon absorption and enhanced carrier collection.

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

Fabrication of amorphous silica nanowires via oxygen plasma treatment of polymers on silicon

Science.gov (United States)

Chen, Zhuojie; She, Didi; Chen, Qinghua; Li, Yanmei; Wu, Wengang

2018-02-01

We demonstrate a facile non-catalytic method of fabricating silica nanowires at room temperature. Different polymers including photoresists, parylene C and polystyrene are patterned into pedestals on the silicon substrates. The silica nanowires are obtained via the oxygen plasma treatment on those pedestals. Compared to traditional strategies of silica nanowire fabrication, this method is much simpler and low-cost. Through designing the proper initial patterns and plasma process parameters, the method can be used to fabricate various regiment nano-scale silica structure arrays in any laboratory with a regular oxygen-plasma-based cleaner or reactive-ion-etching equipment.

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....

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

Science.gov (United States)

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

2016-05-01

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

Fluorinated alkyne-derived monolayers on oxide-free silicon nanowires via one-step hydrosilylation

Energy Technology Data Exchange (ETDEWEB)

Nguyen Minh, Quyen [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Nanosens, IJsselkade 7, 7201 HB Zutphen (Netherlands); Pujari, Sidharam P. [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Wang, Bin [The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa 3200003 (Israel); Wang, Zhanhua [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Haick, Hossam [The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa 3200003 (Israel); Zuilhof, Han [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Rijn, Cees J.M. van, E-mail: cees.vanrijn@wur.nl [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands)

2016-11-30

Highlights: • Oxide-free H-terminated silicon nanowires undergo efficient surface modification by reaction with fluorinated 1-alkynes (HC≡C−(CH{sub 2}){sub 6}C{sub 8}H{sub 17−x}F{sub x}; x = 0–17). • These surface-modified Si NWs are chemically stable under range of conditions (including acid, base). • The surface coating yields efficient electrical passivation as demonstrated by a near-zero electrochemical activity of the surface. - Abstract: Passivation of oxide-free silicon nanowires (Si NWs) by the formation of high-quality fluorinated 1-hexadecyne-derived monolayers with varying fluorine content has been investigated. Alkyl chain monolayers (C{sub 16}H{sub 30−x}F{sub x}) with a varying number of fluorine substituents (x = 0, 1, 3, 9, 17) were attached onto hydrogen-terminated silicon (Si−H) surfaces with an effective one-step hydrosilylation. This surface chemistry gives well-defined monolayers on nanowires that have a cylindrical core–shell structure, as characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and static contact angle (SCA) analysis. The monolayers were stable under acidic and basic conditions, as well as under extreme conditions (such as UV exposure), and provide excellent surface passivation, which opens up applications in the fields of field effect transistors, optoelectronics and especially for disease diagnosis.

Facile synthesis of Prussian blue nanocubes/silver nanowires network as a water-based ink for the direct screen-printed flexible biosensor chips.

Science.gov (United States)

Yang, Pengqi; Peng, Jingmeng; Chu, Zhenyu; Jiang, Danfeng; Jin, Wanqin

2017-06-15

The large-scale fabrication of nanocomposite based biosensors is always a challenge in the technology commercialization from laboratory to industry. In order to address this issue, we have designed a facile chemical method of fabricated nanocomposite ink applied to the screen-printed biosensor chip. This ink can be derived in the water through the in-situ growth of Prussian blue nanocubes (PBNCs) on the silver nanowires (AgNWs) to construct a composite nanostructure by a facile chemical method. Then a miniature flexible biosensor chip was screen-printed by using the prepared nanocomposite ink. Due to the synergic effects of the large specific surface area, high conductivity and electrocatalytic activity from AgNWs and PBNCs, the as-prepared biosensor chip exhibited a fast response (biosensor chip exhibited excellent stability, good reproducibility and high anti-interference ability towards physiological substances under a very low working potential of -0.05. Hence, the proposed biosensor chip also showed a promising potential for the application in practical analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

Hertenberger, Simon

2012-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Hertenberger, Simon

2012-10-15

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

Effective antireflection properties of porous silicon nanowires for photovoltaic applications

KAUST Repository

Najar, Adel

2013-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-11-30

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

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

International Nuclear Information System (INIS)

Llobet, Jordi; Pérez-Murano, Francesc; Krali, Emiljana; Wang, Chen; Jones, Mervyn E.; Durrani, Zahid A. K.; Arbiol, Jordi

2015-01-01

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

Construction of highly ordered polyaniline nanowires and their applications in DNA sensing.

Science.gov (United States)

Hao, Yuanqiang; Zhou, Binbin; Wang, Fangbin; Li, Juan; Deng, Liu; Liu, You-Nian

2014-02-15

A novel electrochemical active polyaniline (PANI) nanowire was fabricated and utilized for the construction of a highly sensitive and selective electrochemical sensor for hepatitis B virus gene. The uniform PANI nanowire was prepared by the enzymatic polymerization of aniline monomers on the amyloid-like nanofiber (AP nanowire), which was self-assembled from an aniline-attached nonapeptide, aniline-GGAAKLVFF (AP). The prepared PANI nanowires were characterized by electron microscopy, UV-vis absorption spectra, and cyclic voltammetry (CV). These ultra-thin nanowires displayed high electrochemical activity. Then the nucleic acid biosensor was constructed by modifying a glass carbon electrode with AP nanowires which were functionalized by a designed hair-pin loop DNA. Upon the presence of target nucleic acid and horseradish peroxidase (HRP) labeled oligonucleotide, the HRP will catalyze the polymerization of aniline monomers conjugated in AP nanowires, leading to the formation of PANI nanowires which can bring about a dramatical increase in the current response of the biosensor. The dynamic range of the sensor for hepatitis B virus gene is 2.0-800.0 fM with a low detection limit of 1.0 fM (3σ, n=10). The biosensor also displayed highly selectivity and stability. All these excellent performances of the developed biosensor indicate that this platform can be easily extended to the detection of other nucleic acids. © 2013 Elsevier B.V. All rights reserved.

Fabricating a silicon nanowire by using the proximity effect in electron beam lithography for investigation of the Coulomb blockade effect

International Nuclear Information System (INIS)

Zhang Xiangao; Fang Zhonghui; Chen Kunji; Xu Jun; Huang Xinfan

2011-01-01

We present an approach to fabricate a silicon nanowire relying on the proximity effect in electron beam lithography with a low acceleration voltage system by designing the exposure patterns with a rhombus sandwiched between two symmetric wedges. The reproducibility is investigated by changing the number of rhombuses. A device with a silicon nanowire is constructed on a highly doped silicon-on-insulator wafer to measure the electronic transport characteristics. Significant nonlinear behavior of current-voltage curves is observed at up to 150 K. The dependence of current on the drain voltage and back-gate voltage shows Coulomb blockade oscillations at 5.4 K, revealing a Coulomb island naturally formed in the nanowire. The mechanism of formation of the Coulomb island is discussed.

Influence of the doping level on the porosity of silicon nanowires prepared by metal-assisted chemical etching

International Nuclear Information System (INIS)

Geyer, Nadine; Wollschläger, Nicole; Tonkikh, Alexander; Berger, Andreas; Werner, Peter; Fuhrmann, Bodo; Leipner, Hartmut S; Jungmann, Marco; Krause-Rehberg, Reinhard

2015-01-01

A systematic method to control the porosity of silicon nanowires is presented. This method is based on metal-assisted chemical etching (MACE) and takes advantage of an HF/H_2O_2 etching solution and a silver catalyst in the form of a thin patterned film deposited on a doped silicon wafer. It is found that the porosity of the etched nanowires can be controlled by the doping level of the wafer. For low doping concentrations, the wires are primarily crystalline and surrounded by only a very thin layer of porous silicon (pSi) layer, while for highly doped silicon, they are porous in their entire volume. We performed a series of controlled experiments to conclude that there exists a well-defined critical doping concentration separating the crystalline and porous regimes. Furthermore, transmission electron microscopy investigations showed that the pSi has also a crystalline morphology on a length scale smaller than the pore size, determined from positron annihilation lifetime spectroscopy to be mesoscopic. Based on the experimental evidence, we devise a theoretical model of the pSi formation during MACE and apply it for better control of the nanowire morphology. (paper)

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

Directory of Open Access Journals (Sweden)

Chien-Wei Liu

2012-01-01

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

Crystallinity, Surface Morphology, and Photoelectrochemical Effects in Conical InP and InN Nanowires Grown on Silicon.

Science.gov (United States)

Parameshwaran, Vijay; Xu, Xiaoqing; Clemens, Bruce

2016-08-24

The growth conditions of two types of indium-based III-V nanowires, InP and InN, are tailored such that instead of yielding conventional wire-type morphologies, single-crystal conical structures are formed with an enlarged diameter either near the base or near the tip. By using indium droplets as a growth catalyst, combined with an excess indium supply during growth, "ice cream cone" type structures are formed with a nanowire "cone" and an indium-based "ice cream" droplet on top for both InP and InN. Surface polycrystallinity and annihilation of the catalyst tip of the conical InP nanowires are observed when the indium supply is turned off during the growth process. This growth design technique is extended to create single-crystal InN nanowires with the same morphology. Conical InN nanowires with an enlarged base are obtained through the use of an excess combined Au-In growth catalyst. Electrochemical studies of the InP nanowires on silicon demonstrate a reduction photocurrent as a proof of photovolatic behavior and provide insight as to how the observed surface polycrystallinity and the resulting interface affect these device-level properties. Additionally, a photovoltage is induced in both types of conical InN nanowires on silicon, which is not replicated in epitaxial InN thin films.

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

International Nuclear Information System (INIS)

Prosini, Pier Paolo; Rufoloni, Alessandro; Rondino, Flaminia; Santoni, Antonino

2014-01-01

In this paper the synthesis and characterization of silicon nanowires to be used as the anode of a lithium-ion battery cell are reported. The nanowires were synthesized by CVD and characterized by SEM. The nanostructured material was used as an electrode in a lithium cell and its electrochemical properties were investigated by galvanostatic charge/discharge cycles at C/10 rate as a function of the cycle number and at various rates as a function of the charge current. The electrode was then coupled with a LiFePO 4 cathode to fabricate a lithium-ion battery cell and the cell performance evaluated by galvanostatic charge/discharge cycles

Enzyme biosensor systems based on porous silicon photoluminescence for detection of glucose, urea and heavy metals.

Science.gov (United States)

Syshchyk, Olga; Skryshevsky, Valeriy A; Soldatkin, Oleksandr O; Soldatkin, Alexey P

2015-04-15

A phenomenon of changes in photoluminescence of porous silicon at variations in medium pH is proposed to be used as a basis for the biosensor system development. The method of conversion of a biochemical signal into an optical one is applied for direct determination of glucose and urea as well as for inhibitory analysis of heavy metal ions. Changes in the quantum yield of porous silicon photoluminescence occur at varying pH of the tested solution due to the enzyme-substrate reaction. When creating the biosensor systems, the enzymes urease and glucose oxidase (GOD) were used as a bioselective material; their optimal concentrations were experimentally determined. It was shown that the photoluminescence intensity of porous silicon increased by 1.7 times when increasing glucose concentration in the GOD-containing reaction medium from 0 to 3.0mM, and decreased by 1.45 times at the same increase in the urea concentration in the urease-containing reaction medium. The calibration curves of dependence of the biosensor system responses on the substrate concentrations are presented. It is shown that the presence of heavy metal ions (Cu(2+), Pb(2+), and Cd(2+)) in the tested solution causes an inhibition of the enzymatic reactions catalyzed by glucose oxidase and urease, which results in a restoration of the photoluminescence quantum yield of porous silicon. It is proposed to use this effect for the inhibitory analysis of heavy metal ions. Copyright © 2014 Elsevier B.V. All rights reserved.

Photoresponsive properties of ultrathin silicon nanowires

International Nuclear Information System (INIS)

Tran, Duy P.; Macdonald, Thomas J.; Nann, Thomas; Thierry, Benjamin; Wolfrum, Bernhard; Stockmann, Regina; Offenhäusser, Andreas

2014-01-01

Functional silicon nanowires (SiNWs) are promising building blocks in the design of highly sensitive photodetectors and bio-chemical sensors. We systematically investigate the photoresponse properties of ultrathin SiNWs (20 nm) fabricated using a size-reduction method based on e-beam lithography and tetramethylammonium hydroxide wet-etching. The high-quality SiNWs were able to detect light from the UV to the visible range with excellent sensitivity (∼1 pW/array), good time response, and high photoresponsivity (R ∼ 2.5 × 10 4  A/W). Improvement of the ultrathin SiNWs' photoresponse has been observed in comparison to 40 nm counter-part nanowires. These properties are attributable to the predominance surface-effect due to the high surface-to-volume ratio of ultrathin SiNWs. Long-term measurements at different temperatures in both the forward and reverse bias directions demonstrated the stability and reliability of the fabricated device. By sensitizing the fabricated SiNW arrays with cadmium telluride quantum dots (QDs), hybrid QD SiNW devices displayed an improvement in photocurrent response under UV light, while preserving their performance in the visible light range. The fast, stable, and high photoresponse of these hybrid nanostructures is promising towards the development of optoelectronic and photovoltaic devices

Photoresponsive properties of ultrathin silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

Tran, Duy P.; Macdonald, Thomas J.; Nann, Thomas; Thierry, Benjamin, E-mail: a.offenhaeusser@fz-juelich.de, E-mail: benjamin.thierry@unisa.edu.au [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, MM Bldg., Mawson Lakes Blvd., Mawson Lakes, South Australia 5095 (Australia); Wolfrum, Bernhard; Stockmann, Regina; Offenhäusser, Andreas, E-mail: a.offenhaeusser@fz-juelich.de, E-mail: benjamin.thierry@unisa.edu.au [Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 2.4v Bldg., Wilhelm-Johnen St., Jülich 52428 (Germany)

2014-12-08

Functional silicon nanowires (SiNWs) are promising building blocks in the design of highly sensitive photodetectors and bio-chemical sensors. We systematically investigate the photoresponse properties of ultrathin SiNWs (20 nm) fabricated using a size-reduction method based on e-beam lithography and tetramethylammonium hydroxide wet-etching. The high-quality SiNWs were able to detect light from the UV to the visible range with excellent sensitivity (∼1 pW/array), good time response, and high photoresponsivity (R ∼ 2.5 × 10{sup 4 }A/W). Improvement of the ultrathin SiNWs' photoresponse has been observed in comparison to 40 nm counter-part nanowires. These properties are attributable to the predominance surface-effect due to the high surface-to-volume ratio of ultrathin SiNWs. Long-term measurements at different temperatures in both the forward and reverse bias directions demonstrated the stability and reliability of the fabricated device. By sensitizing the fabricated SiNW arrays with cadmium telluride quantum dots (QDs), hybrid QD SiNW devices displayed an improvement in photocurrent response under UV light, while preserving their performance in the visible light range. The fast, stable, and high photoresponse of these hybrid nanostructures is promising towards the development of optoelectronic and photovoltaic devices.

High density micro-pyramids with silicon nanowire array for photovoltaic applications

International Nuclear Information System (INIS)

Rahman, Tasmiat; Navarro-Cía, Miguel; Fobelets, Kristel

2014-01-01

We use a metal assisted chemical etch process to fabricate silicon nanowire arrays (SiNWAs) onto a dense periodic array of pyramids that are formed using an alkaline etch masked with an oxide layer. The hybrid micro-nano structure acts as an anti-reflective coating with experimental reflectivity below 1% over the visible and near-infrared spectral regions. This represents an improvement of up to 11 and 14 times compared to the pyramid array and SiNWAs on bulk, respectively. In addition to the experimental work, we optically simulate the hybrid structure using a commercial finite difference time domain package. The results of the optical simulations support our experimental work, illustrating a reduced reflectivity in the hybrid structure. The nanowire array increases the absorbed carrier density within the pyramid by providing a guided transition of the refractive index along the light path from air into the silicon. Furthermore, electrical simulations which take into account surface and Auger recombination show an efficiency increase for the hybrid structure of 56% over bulk, 11% over pyramid array and 8.5% over SiNWAs. (paper)

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

International Nuclear Information System (INIS)

Uchida, Takafumi; Jo, Mingyu; Tsurumaki-Fukuchi, Atsushi; Arita, Masashi; Takahashi, Yasuo; Fujiwara, Akira

2015-01-01

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

Molecular layer deposition of APTES on silicon nanowire biosensors: Surface characterization, stability and pH response

International Nuclear Information System (INIS)

Liang, Yuchen; Huang, Jie; Zang, Pengyuan; Kim, Jiyoung; Hu, Walter

2014-01-01

Graphical abstract: - Abstract: We report the use of molecular layer deposition (MLD) for depositing 3-aminopropyltriethoxysilane (APTES) on a silicon dioxide surface. The APTES monolayer was characterized using spectroscopic ellipsometry, contact angle goniometry, and atomic force microscopy. Effects of reaction time of repeating pulses and simultaneous feeding of water vapor with APTES were tested. The results indicate that the synergistic effects of water vapor and reaction time are significant for the formation of a stable monolayer. Additionally, increasing the number of repeating pulses improved the APTES surface coverage but led to saturation after 10 pulses. In comparing MLD with solution-phase deposition, the APTES surface coverage and the surface quality were nearly equivalent. The hydrolytic stability of the resulting films was also studied. The results confirmed that the hydrolysis process was necessary for MLD to obtain stable surface chemistry. Furthermore, we compared the pH sensing results of Si nanowire field effect transistors (Si NWFETs) modified by both the MLD and solution methods. The highly repeatable pH sensing results reflected the stability of APTES monolayers. The results also showed an improved pH response of the sensor prepared by MLD compared to the one prepared by the solution treatment, which indicated higher surface coverage of APTES

Molecular layer deposition of APTES on silicon nanowire biosensors: Surface characterization, stability and pH response

Science.gov (United States)

Liang, Yuchen; Huang, Jie; Zang, Pengyuan; Kim, Jiyoung; Hu, Walter

2014-12-01

We report the use of molecular layer deposition (MLD) for depositing 3-aminopropyltriethoxysilane (APTES) on a silicon dioxide surface. The APTES monolayer was characterized using spectroscopic ellipsometry, contact angle goniometry, and atomic force microscopy. Effects of reaction time of repeating pulses and simultaneous feeding of water vapor with APTES were tested. The results indicate that the synergistic effects of water vapor and reaction time are significant for the formation of a stable monolayer. Additionally, increasing the number of repeating pulses improved the APTES surface coverage but led to saturation after 10 pulses. In comparing MLD with solution-phase deposition, the APTES surface coverage and the surface quality were nearly equivalent. The hydrolytic stability of the resulting films was also studied. The results confirmed that the hydrolysis process was necessary for MLD to obtain stable surface chemistry. Furthermore, we compared the pH sensing results of Si nanowire field effect transistors (Si NWFETs) modified by both the MLD and solution methods. The highly repeatable pH sensing results reflected the stability of APTES monolayers. The results also showed an improved pH response of the sensor prepared by MLD compared to the one prepared by the solution treatment, which indicated higher surface coverage of APTES.

All-(111) surface silicon nanowire field effect transistor devices: Effects of surface preparations

NARCIS (Netherlands)

Masood, M.N.; Carlen, Edwin; van den Berg, Albert

2014-01-01

Etching/hydrogen termination of All-(111) surface silicon nanowire field effect (SiNW-FET) devices developed by conventional photolithography and plane dependent wet etchings is studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and

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

Science.gov (United States)

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

2016-01-13

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

Design and simulation of MEMS microvalves for silicon photonic biosensor chip

Science.gov (United States)

Amemiya, Yoshiteru; Nakashima, Yuuto; Maeda, Jun; Yokoyama, Shin

2018-04-01

For the early and easy diagnosis of diseases, we have proposed a silicon photonic biosensor chip with two kinds of MEMS microvalves for a multiple-item detection system. The driving voltage of the vertical type with the circular-plate capacitor structure and that of the lateral type with the comb-shaped electrode are investigated. From mechanical calculations, the driving voltage of the vertical type is estimated to be 30 V and that of the lateral type to be 15 V. The propagation loss at the intersecting waveguides of arrayed ring-resonator biosensors is also estimated. In the case of optimized intersecting waveguides, more than 67% transmittance of TE-mode light is simulated for the series connection of 20 intersecting waveguides. It is confirmed that it is possible to fabricate an 8 × 12 arrayed biosensor chip in an area of 1 × 1.5 mm2 taking the device size of the microvalves into consideration. We have, for the first time, designed a whole system, including sensors and a fluid channel with MEMS microvalves.

Monolithic integration of a silicon nanowire field-effect transistors array on a complementary metal-oxide semiconductor chip for biochemical sensor applications.

Science.gov (United States)

Livi, Paolo; Kwiat, Moria; Shadmani, Amir; Pevzner, Alexander; Navarra, Giulio; Rothe, Jörg; Stettler, Alexander; Chen, Yihui; Patolsky, Fernando; Hierlemann, Andreas

2015-10-06

We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I-V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized nanowire FETs.

pH-controlled silicon nanowires fluorescence switch

International Nuclear Information System (INIS)

Mu Lixuan; Shi Wensheng; Zhang Taiping; Zhang Hongyan; She Guangwei

2010-01-01

Covalently immobilizing photoinduced electronic transfer (PET) fluorophore 3-[N, N-bis(9-anthrylmethyl)amino]-propyltriethoxysilane (DiAN) on the surface of silicon nanowires (SiNWs) resulted a SiNWs-based fluorescence switch. This fluorescence switch is operated by adjustment of the acidity of the environment and exhibits sensitive response to pH at the range from 8 to 10. Such response is attributed to the effect of pH on the PET process. The successful combination of logic switch and SiNWs provides a rational approach to assemble different logic molecules on SiNWs for realization of miniaturization and modularization of switches and logic devices.

APPLIED OPTICS. Voltage-tunable circular photogalvanic effect in silicon nanowires.

Science.gov (United States)

Dhara, Sajal; Mele, Eugene J; Agarwal, Ritesh

2015-08-14

Electronic bands in crystals can support nontrivial topological textures arising from spin-orbit interactions, but purely orbital mechanisms can realize closely related dynamics without breaking spin degeneracies, opening up applications in materials containing only light elements. One such application is the circular photogalvanic effect (CPGE), which is the generation of photocurrents whose magnitude and polarity depend on the chirality of optical excitation. We show that the CPGE can arise from interband transitions at the metal contacts to silicon nanowires, where inversion symmetry is locally broken by an electric field. Bias voltage that modulates this field further controls the sign and magnitude of the CPGE. The generation of chirality-dependent photocurrents in silicon with a purely orbital-based mechanism will enable new functionalities in silicon that can be integrated with conventional electronics. Copyright © 2015, American Association for the Advancement of Science.

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

Science.gov (United States)

Guerfi, Youssouf; Larrieu, Guilhem

2016-04-01

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

Effects of buffer composition and dilution on nanowire field-effect biosensors

International Nuclear Information System (INIS)

Lloret, Noémie; Frederiksen, Rune S; Møller, Thor C; Rieben, Nathalie I; Martinez, Karen L; Upadhyay, Shivendra; Nygård, Jesper; De Vico, Luca; Jensen, Jan H

2013-01-01

Nanowire-based field-effect transistors (FETs) can be used as ultra-sensitive and label-free biosensors for detecting protein–protein interactions. A way to increase the performance of such sensors is to dilute the sensing buffer drastically. However, we show here that this can have an important effect on the function of the proteins. Moreover, it is demonstrated that this dilution significantly affects the pH stability of the sensing buffer, which consequently impacts the charge of the protein and thus the response and signal-to-noise ratio in the sensing experiments. Three model systems are investigated experimentally to illustrate the impact on ligand–protein and protein–protein interactions. Simulations are performed to illustrate the effect on the performance of the sensors. Combining various parameters, the current study provides a means for evaluating and selecting the most appropriate buffer composition for bioFET measurements. (paper)

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

Science.gov (United States)

Sun, Zhelin; Wang, Deli; Xiang, Jie

2014-11-25

Spontaneous attractions between free-standing nanostructures have often caused adhesion or stiction that affects a wide range of nanoscale devices, particularly nano/microelectromechanical systems. Previous understandings of the attraction mechanisms have included capillary force, van der Waals/Casimir forces, and surface polar charges. However, none of these mechanisms universally applies to simple semiconductor structures such as silicon nanowire arrays that often exhibit bunching or adhesions. Here we propose a simple capacitive force model to quantitatively study the universal spontaneous attraction that often causes stiction among semiconductor or metallic nanostructures such as vertical nanowire arrays with inevitably nonuniform size variations due to fabrication. When nanostructures are uniform in size, they share the same substrate potential. The presence of slight size differences will break the symmetry in the capacitive network formed between the nanowires, substrate, and their environment, giving rise to electrostatic attraction forces due to the relative potential difference between neighboring wires. Our model is experimentally verified using arrays of vertical silicon nanowire pairs with varied spacing, diameter, and size differences. Threshold nanowire spacing, diameter, or size difference between the nearest neighbors has been identified beyond which the nanowires start to exhibit spontaneous attraction that leads to bridging when electrostatic forces overcome elastic restoration forces. This work illustrates a universal understanding of spontaneous attraction that will impact the design, fabrication, and reliable operation of nanoscale devices and systems.

Porous silicon biosensor for the detection of autoimmune diseases

Science.gov (United States)

Jane, Andrew O.; Szili, Endre J.; Reed, Joanne H.; Gordon, Tom P.; Voelcker, Nicolas H.

2007-12-01

Advances in porous silicon (pSi) technology have led to the development of new sensitive biosensors. The unique optical properties of pSi renders the material a perfect candidate for optical transducers exploiting photoluminescence or white light interference effects. The ability of biosensors exploiting these transduction mechanisms to quickly and accurately detect biological target molecules affords an alternative to current bioassays such as enzyme-linked immunosorbent assays (ELISAs). Here, we present a pSi biosensor that was developed to detect antibodies against the autoimmune protein La. This protein is associated with autoimmune diseases including rheumatic disorders, systematic lupus erythematosus (SLE) and Sjogren's syndrome (SS). A fast and sensitive detection platform such as the one described here can be applied to the rapid diagnosis of these debilitating autoimmune diseases. The immobilisation of the La protein onto pSi films gave a protein receptor-decorated sensor matrix. A cascade of immunological reactions was then initiated to detect anti-La antibody on the functionalised pSi surface. In the presence of o-phenylenediamine (OPD), horseradish peroxidase (HRP)/H IIO II catalysed the formation of an oxidised radical species that accelerated pSi corrosion. pSi corrosion was detected as a blue-shift in the generated interference pattern, corresponding to a decrease in the effective optical thickness (EOT) of the pSi film. Compared to an ELISA, the pSi biosensor could detect the anti-La antibody at a similar concentration (500 - 125 ng/ml). Furthermore, we found that the experimental process can be significantly shortened resulting in detection of the anti-La antibody in 80 minutes compared to a minimum of 5 hours required for ELISA.

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

KAUST Repository

Cui, Li-Feng; Ruffo, Riccardo; Chan, Candace K.; Peng, Hailin; Cui, Yi

2009-01-01

fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower

Comparison of confinement characters between porous silicon and silicon nanowires

International Nuclear Information System (INIS)

Tit, Nacir; Yamani, Zain H.; Pizzi, Giovanni; Virgilio, Michele

2011-01-01

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

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....

High-Temperature Performance of Stacked Silicon Nanowires for Thermoelectric Power Generation

Science.gov (United States)

Stranz, Andrej; Waag, Andreas; Peiner, Erwin

2013-07-01

Deep reactive-ion etching at cryogenic temperatures (cryo-DRIE) has been used to produce arrays of silicon nanowires (NWs) for thermoelectric (TE) power generation devices. Using cryo-DRIE, we were able to fabricate NWs of large aspect ratios (up to 32) using a photoresist mask. Roughening of the NW sidewalls occurred, which has been recognized as beneficial for low thermal conductivity. Generated NWs, which were 7 μm in length and 220 nm to 270 nm in diameter, were robust enough to be stacked with a bulk silicon chip as a common top contact to the NWs. Mechanical support of the NW array, which can be created by filling the free space between the NWs using silicon oxide or polyimide, was not required. The Seebeck voltage, measured across multiple stacks of up to 16 bulk silicon dies, revealed negligible thermal interface resistance. With stacked silicon NWs, we observed Seebeck voltages that were an order of magnitude higher than those observed for bulk silicon. Degradation of the TE performance of silicon NWs was not observed for temperatures up to 470°C and temperature gradients up to 170 K.

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.

Photonic Torque Microscopy of the Nonconservative Force Field for Optically Trapped Silicon Nanowires

Czech Academy of Sciences Publication Activity Database

Irrera, A.; Maggazu, A.; Artoni, P.; Simpson, Stephen Hugh; Hanna, S.; Jones, P.H.; Priolo, F.; Gucciardi, P. G.; Marago, O.M.

2016-01-01

Roč. 16, č. 7 (2016), s. 4181-4188 ISSN 1530-6984 R&D Projects: GA ČR GB14-36681G Institutional support: RVO:68081731 Keywords : optical tweezers * silicon nanowires * nonequilibrium dynamics * Brownian motion Subject RIV: BH - Optics, Masers, Lasers Impact factor: 12.712, year: 2016

Reducing the porosity and reflection loss of silicon nanowires by a sticky tape

International Nuclear Information System (INIS)

Liu, Junjun; Huang, Zhifeng

2015-01-01

Engineering the porosity of silicon nanowires (SiNWs) is of fundamental importance, and this work introduces a new method for doing so. Metal-assisted chemical etching (MACE) of heavily doped Si(100) creates mesoporous silicon nanowires (mp-SiNWs). mp-SiNWs are transferred from the MACE-treated wafer to a sticky tape, leaving residues composed of broken mp-SiNWs and a mesoporous Si layer on the wafer. Then the taped wafer is re-treated by MACE, without changing the etching conditions. The second MACE treatment generates mp-SiNWs that are less porous and longer than those generated by the first MACE treatment, which can be attributed to the difference in the surface topography at the beginning of the etching process. Less porous mp-SiNWs reduce optical scattering from the porous Si skeletons, and vertically protrude on the wafer without aggregation to facilitate optical trapping. Consequently, less porous mp-SiNWs effectively reduce ultraviolet-visible reflection loss. (paper)

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

KAUST Repository

Ball, Jeremy

2012-08-20

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

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

KAUST Repository

Ball, Jeremy; Centeno, Anthony; Mendis, Budhika G.; Reehal, H. S.; Alford, Neil

2012-01-01

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

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

International Nuclear Information System (INIS)

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

2016-01-01

Graphical abstract: - Highlights: • We prepared graphene on top of silicon nanowires by transfer-print technique. • Graphene changed from discrete flakes to a continuous by repeated transfer-print. • The triple-layer graphene had high electron field emission due to large edge ratio. - Abstract: Monolayer graphene was grown on copper foils and then transferred on planar silicon substrates and on top of silicon nanowire (SiNW) arrays to form single- to quadruple-layer graphene films. The morphology, structure, and electron field emission (FE) of these graphene films were investigated. The graphene films on the planar silicon substrates were continuous. The single- to triple-layer graphene films on the SiNW arrays were discontinuous and while the quadruple-layer graphene film featured a mostly continuous area. The Raman spectra of the graphene films on the SiNW arrays showed G and G′ bands with a singular-Lorentzian shape together with a weak D band. The D band intensity decreased as the number of graphene layers increased. The FE efficiency of the graphene films on the planar silicon substrates and the SiNW arrays varied with the number of graphene layers. The turn-on field for the single- to quadruple-layer graphene films on planar silicon substrates were 4.3, 3.7, 3.5 and 3.4 V/μm, respectively. The turn-on field for the single- to quadruple-layer graphene films on SiNW arrays decreased to 3.9, 3.3, 3.0 and 3.3 V/μm, respectively. Correlation of the FE with structure and morphology of the graphene films is discussed.

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

Energy Technology Data Exchange (ETDEWEB)

Huang, Bohr-Ran; Chan, Hui-Wen [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Jou, Shyankay, E-mail: sjou@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Chen, Guan-Yu [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Kuo, Hsiu-An; Song, Wan-Jhen [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China)

2016-01-30

Graphical abstract: - Highlights: • We prepared graphene on top of silicon nanowires by transfer-print technique. • Graphene changed from discrete flakes to a continuous by repeated transfer-print. • The triple-layer graphene had high electron field emission due to large edge ratio. - Abstract: Monolayer graphene was grown on copper foils and then transferred on planar silicon substrates and on top of silicon nanowire (SiNW) arrays to form single- to quadruple-layer graphene films. The morphology, structure, and electron field emission (FE) of these graphene films were investigated. The graphene films on the planar silicon substrates were continuous. The single- to triple-layer graphene films on the SiNW arrays were discontinuous and while the quadruple-layer graphene film featured a mostly continuous area. The Raman spectra of the graphene films on the SiNW arrays showed G and G′ bands with a singular-Lorentzian shape together with a weak D band. The D band intensity decreased as the number of graphene layers increased. The FE efficiency of the graphene films on the planar silicon substrates and the SiNW arrays varied with the number of graphene layers. The turn-on field for the single- to quadruple-layer graphene films on planar silicon substrates were 4.3, 3.7, 3.5 and 3.4 V/μm, respectively. The turn-on field for the single- to quadruple-layer graphene films on SiNW arrays decreased to 3.9, 3.3, 3.0 and 3.3 V/μm, respectively. Correlation of the FE with structure and morphology of the graphene films is discussed.

Nonlinear Dynamics of Silicon Nanowire Resonator Considering Nonlocal Effect.

Science.gov (United States)

Jin, Leisheng; Li, Lijie

2017-12-01

In this work, nonlinear dynamics of silicon nanowire resonator considering nonlocal effect has been investigated. For the first time, dynamical parameters (e.g., resonant frequency, Duffing coefficient, and the damping ratio) that directly influence the nonlinear dynamics of the nanostructure have been derived. Subsequently, by calculating their response with the varied nonlocal coefficient, it is unveiled that the nonlocal effect makes more obvious impacts at the starting range (from zero to a small value), while the impact of nonlocal effect becomes weaker when the nonlocal term reaches to a certain threshold value. Furthermore, to characterize the role played by nonlocal effect in exerting influence on nonlinear behaviors such as bifurcation and chaos (typical phenomena in nonlinear dynamics of nanoscale devices), we have calculated the Lyapunov exponents and bifurcation diagram with and without nonlocal effect, and results shows the nonlocal effect causes the most significant effect as the device is at resonance. This work advances the development of nanowire resonators that are working beyond linear regime.

Optical waveform sampling and error-free demultiplexing of 1.28 Tbit/s serial data in a silicon nanowire

DEFF Research Database (Denmark)

Ji, Hua; Hu, Hao; Galili, Michael

2010-01-01

We experimentally demonstrate 640 Gbit/s and 1.28 Tbit/s serial data optical waveform sampling and 640-to-10 Gbit/s and 1.28 Tbit/s-to-10 Gbit/s error-free demultiplexing using four-wave mixing in a 300nm$$450nm$$5mm silicon nanowire.......We experimentally demonstrate 640 Gbit/s and 1.28 Tbit/s serial data optical waveform sampling and 640-to-10 Gbit/s and 1.28 Tbit/s-to-10 Gbit/s error-free demultiplexing using four-wave mixing in a 300nm$$450nm$$5mm silicon nanowire....

Synthesis of the cactus-like silicon nanowires/tungsten oxide nanowires composite for room-temperature NO{sub 2} gas sensor

Energy Technology Data Exchange (ETDEWEB)

Zhang, Weiyi, E-mail: zhangweiyi@tju.edu.cn [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Hu, Ming [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Key Laboratory for Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Liu, Xing; Wei, Yulong; Li, Na [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Qin, Yuxiang, E-mail: qinyuxiang@tju.edu.cn [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Key Laboratory for Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

2016-09-15

In the present work, the tungsten oxide (WO{sub 3}) nanowires functionalized silicon nanowires (SiNWs) with cactus-like structure has been successfully synthesized for room-temperature NO{sub 2} detection. The novel nanocomposite was fabricated by metal-assisted chemical etching (MACE) and thermal annealing of tungsten film. The WO{sub 3} nanowires were evenly distributed from the upper to the lower part of the SiNWs, indicating excellent uniformity which is conducive to adsorption and desorption of gas molecules. The gas-sensing properties have been examined by measuring the resistance change towards 0.25–5 ppm NO{sub 2} gas. At room temperature, which is the optimum working temperature, the SiNWs/WO{sub 3} nanowires composite showed two-times higher NO{sub 2} response than that of the bare SiNWs at 2 ppm NO{sub 2}. On the contrary, the responses of composite sensors to high concentrations of other reducing gases were very low, indicating excellent selectivity. Simultaneously, the composite sensors exhibited good sensing repeatability and stability. The enhancement in gas sensing properties may be attributed to the change in width of the space charge region, which is similar to the behavior of p-n junctions under forward bias, in the high-density p-n heterojunction structure formed between SiNWs and WO{sub 3} nanowires. - Highlights: • SiNWs/WO{sub 3} nanowires composite with cactus-like structure is synthesized. • The morphology of WO{sub 3} nanowires depends on the thermal annealing temperature. • The nanocomposite sensor exhibit better gas response than that of bare SiNWs. • The gas sensing mechanism is discussed using p-n heterojunction theory.

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

Optimal design of aperiodic, vertical silicon nanowire structures for photovoltaics.

Science.gov (United States)

Lin, Chenxi; Povinelli, Michelle L

2011-09-12

We design a partially aperiodic, vertically-aligned silicon nanowire array that maximizes photovoltaic absorption. The optimal structure is obtained using a random walk algorithm with transfer matrix method based electromagnetic forward solver. The optimal, aperiodic structure exhibits a 2.35 times enhancement in ultimate efficiency compared to its periodic counterpart. The spectral behavior mimics that of a periodic array with larger lattice constant. For our system, we find that randomly-selected, aperiodic structures invariably outperform the periodic array.

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

Science.gov (United States)

2013-01-01

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

High-performance silicon nanowire bipolar phototransistors

Science.gov (United States)

Tan, Siew Li; Zhao, Xingyan; Chen, Kaixiang; Crozier, Kenneth B.; Dan, Yaping

2016-07-01

Silicon nanowires (SiNWs) have emerged as sensitive absorbing materials for photodetection at wavelengths ranging from ultraviolet (UV) to the near infrared. Most of the reports on SiNW photodetectors are based on photoconductor, photodiode, or field-effect transistor device structures. These SiNW devices each have their own advantages and trade-offs in optical gain, response time, operating voltage, and dark current noise. Here, we report on the experimental realization of single SiNW bipolar phototransistors on silicon-on-insulator substrates. Our SiNW devices are based on bipolar transistor structures with an optically injected base region and are fabricated using CMOS-compatible processes. The experimentally measured optoelectronic characteristics of the SiNW phototransistors are in good agreement with simulation results. The SiNW phototransistors exhibit significantly enhanced response to UV and visible light, compared with typical Si p-i-n photodiodes. The near infrared responsivities of the SiNW phototransistors are comparable to those of Si avalanche photodiodes but are achieved at much lower operating voltages. Compared with other reported SiNW photodetectors as well as conventional bulk Si photodiodes and phototransistors, the SiNW phototransistors in this work demonstrate the combined advantages of high gain, high photoresponse, low dark current, and low operating voltage.

Reduction of Cr(VI) to Cr(III) using silicon nanowire arrays under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Fellahi, Ouarda [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Barras, Alexandre [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Pan, Guo-Hui [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dong Nanhu Road, Changchun 130033 (China); Coffinier, Yannick [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Hadjersi, Toufik [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Maamache, Mustapha [Laboratoire de Physique Quantique et Systèmes Dynamiques, Département de Physique, Université de Sétif, Sétif 19000 (Algeria); Szunerits, Sabine [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); and others

2016-03-05

Highlights: • Cr(VI) reduction to Cr(III) using silicon nanowires decorated with Cu nanoparticles. • The reduction takes place at room temperature and neutral pH under visible light. • The photocatalytic reduction was enhanced by addition of adipic or citric acid. - Abstract: We report an efficient visible light-induced reduction of hexavalent chromium Cr(VI) to trivalent Cr(III) by direct illumination of an aqueous solution of potassium dichromate (K{sub 2}Cr{sub 2}O{sub 7}) in the presence of hydrogenated silicon nanowires (H-SiNWs) or silicon nanowires decorated with copper nanoparticles (Cu NPs-SiNWs) as photocatalyst. The SiNW arrays investigated in this study were prepared by chemical etching of crystalline silicon in HF/AgNO{sub 3} aqueous solution. The Cu NPs were deposited on SiNW arrays via electroless deposition technique. Visible light irradiation of an aqueous solution of K{sub 2}Cr{sub 2}O{sub 7} (10{sup −4} M) in presence of H-SiNWs showed that these substrates were not efficient for Cr(VI) reduction. The reduction efficiency achieved was less than 10% after 120 min irradiation at λ > 420 nm. Addition of organic acids such as citric or adipic acid in the solution accelerated Cr(VI) reduction in a concentration-dependent manner. Interestingly, Cu NPs-SiNWs was found to be a very efficient interface for the reduction of Cr(VI) to Cr(III) in absence of organic acids. Almost a full reduction of Cr(VI) was achieved by direct visible light irradiation for 140 min using this photocatalyst.

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

KAUST Repository

Guo, Wei; Banerjee, Animesh; Bhattacharya, Pallab K.; Ooi, Boon S.

2011-01-01

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

Towards a subcutaneous optical biosensor based on thermally hydrocarbonised porous silicon.

Science.gov (United States)

Tong, Wing Yin; Sweetman, Martin J; Marzouk, Ezzat R; Fraser, Cara; Kuchel, Tim; Voelcker, Nicolas H

2016-01-01

Advanced biosensors in future medicine hinge on the evolvement of biomaterials. Porous silicon (pSi), a generally biodegradable and biocompatible material that can be fabricated to include environment-responsive optical characteristics, is an excellent candidate for in vivo biosensors. However, the feasibility of using this material as a subcutaneously implanted optical biosensor has never been demonstrated. Here, we investigated the stability and biocompatibility of a thermally-hydrocarbonised (THC) pSi optical rugate filter, and demonstrated its optical functionality in vitro and in vivo. We first compared pSi films with different surface chemistries and observed that the material was cytotoxic despite the outstanding stability of the THC pSi films. We then showed that the cytotoxicity correlates with reactive oxygen species levels, which could be mitigated by pre-incubation of THC pSi (PITHC pSi). PITHC pSi facilitates normal cellular phenotypes and is biocompatible in vivo. Importantly, the material also possesses optical properties capable of responding to microenvironmental changes that are readable non-invasively in cell culture and subcutaneous settings. Collectively, we demonstrate, for the first time, that PITHC pSi rugate filters are both biocompatible and optically functional for lab-on-a-chip and subcutaneous biosensing scenarios. We believe that this study will deepen our understanding of cell-pSi interactions and foster the development of implantable biosensors. Copyright © 2015 Elsevier Ltd. All rights reserved.

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)

Catalytic growth of carbon nanowires on composite diamond/silicon substrates

Energy Technology Data Exchange (ETDEWEB)

Sellam, Amine [Université de Lorraine, Institut Jean Lamour, Département CP2S (UMR CNRS 7198), Parc de Saurupt, F-54042 Nancy Cedex (France); Miska, Patrice [Université de Lorraine, Institut Jean Lamour, Département P2M (UMR CNRS 7198), Parc de Saurupt, F-54042 Nancy Cedex (France); Ghanbaja, Jaafar [Université de Lorraine, Institut Jean Lamour, Département CP2S (UMR CNRS 7198), Parc de Saurupt, F-54042 Nancy Cedex (France); Barrat, Silvère, E-mail: Silvere.Barrat@ijl.nancy-universite.fr [Université de Lorraine, Institut Jean Lamour, Département CP2S (UMR CNRS 7198), Parc de Saurupt, F-54042 Nancy Cedex (France)

2014-01-01

Polycrystalline diamond (PCD) films and carbon nanowires (CNWs) provide individually highly attractive properties for science and technology applications. The possibility of carbon composite materials made from a combination of these materials remains a potential approach widely discussed in literature but modestly investigated. We report in this work an early attempt to explore this opportunity in the light of some specific experimental considerations. Carbon nanowires (CNWs) are grown at low temperature without the conventional use of external hydrocarbon vapor source on silicon substrates partially covered by a thin film of coalesced micrometric CVD diamond. Composite substrates constituted by PCD on silicon were first cleaned with H{sub 2} plasma then used for the PVD deposition of 5 nm Ni thin films. Then, samples were heat treated in a CVD reactor at 580 °C in the presence of pure H{sub 2} pressure of 60 hPa at different annealing times. Comparative effect of annealing time on the dewetting of Ni thin films and the subsequent CNWs growth process was considered in this work using systematic observations by SEM. Possible mechanisms underlying CNWs growth in pure H{sub 2} gas were proposed. The nature and structure of these CNWs have been investigated by TEM microscopy and by Raman spectroscopy on the sample showing the highest CNWs density.

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

Directory of Open Access Journals (Sweden)

Wen-Chung Chang

2016-06-01

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

A facile fluorescent sensor based on silicon nanowires for dithionite

Science.gov (United States)

Cao, Xingxing; Mu, Lixuan; Chen, Min; She, Guangwei

2018-05-01

A facile and novel fluorescent sensor for dithionite has been constructed by simultaneously immobilizing dansyl group (fluorescence molecule) and dabsyl group (quencher and recognizing group) on the silicon nanowires (SiNWs) and SiNW arrays surface. This sensor for dithionite exhibited high selectivity and a good relationship of linearity between fluorescence intensities and dithionite concentrations from 0.1 to 1 mM. This approach is straightforward and does not require complicated synthesis, which can be extended to develop other sensors with similar rationale.

A size selective porous silicon grating-coupled Bloch surface and sub-surface wave biosensor.

Science.gov (United States)

Rodriguez, Gilberto A; Ryckman, Judson D; Jiao, Yang; Weiss, Sharon M

2014-03-15

A porous silicon (PSi) grating-coupled Bloch surface and sub-surface wave (BSW/BSSW) biosensor is demonstrated to size selectively detect the presence of both large and small molecules. The BSW is used to sense large immobilized analytes at the surface of the structure while the BSSW that is confined inside but near the top of the structure is used to sensitively detect small molecules. Functionality of the BSW and BSSW modes is theoretically described by dispersion relations, field confinements, and simulated refractive index shifts within the structure. The theoretical results are experimentally verified by detecting two different small chemical molecules and one large 40 base DNA oligonucleotide. The PSi-BSW/BSSW structure is benchmarked against current porous silicon technology and is shown to have a 6-fold higher sensitivity in detecting large molecules and a 33% improvement in detecting small molecules. This is the first report of a grating-coupled BSW biosensor and the first report of a BSSW propagating mode. © 2013 Published by Elsevier B.V.

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

NARCIS (Netherlands)

Moh, T.S.Y.

2013-01-01

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

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...

A p-silicon nanowire/n-ZnO thin film heterojunction diode prepared by thermal evaporation

International Nuclear Information System (INIS)

Hazra, Purnima; Jit, S.

2014-01-01

This paper represents the electrical and optical characteristics of a SiNW/ZnO heterojunction diode and subsequent studies on the photodetection properties of the diode in the ultraviolet (UV) wavelength region. In this work, silicon nanowire arrays were prepared on p-type (100)-oriented Si substrate by an electroless metal deposition and etching method with the help of ultrasonication. After that, catalyst-free deposition of zinc oxide (ZnO) nanowires on a silicon nanowire (SiNW) array substrate was done by utilizing a simple and cost-effective thermal evaporation technique without using a buffer layer. The SEM and XRD techniques are used to show the quality of the as-grown ZnO nanowire film. The junction properties of the diode are evaluated by measuring current—voltage and capacitance—voltage characteristics. The diode has a well-defined rectifying behavior with a rectification ratio of 190 at ±2 V, turn-on voltage of 0.5 V, and barrier height is 0.727 eV at room temperature under dark conditions. The photodetection parameters of the diode are investigated in the bias voltage range of ±2 V. The diode shows responsivity of 0.8 A/W at a bias voltage of 2 V under UV illumination (wavelength = 365 nm). The characteristics of the device indicate that it can be used for UV detection applications in nano-optoelectronic and photonic devices. (semiconductor devices)

Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

KAUST Repository

Ruffo, Riccardo

2009-07-02

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

Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

International Nuclear Information System (INIS)

Ben Dkhil, S.; Bourguiga, R.; Davenas, J.; Cornu, D.

2012-01-01

Highlights: ► Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. ► We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. ► The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. ► We have investigated the effects of SiNWs concentration on the photovoltaic characteristics leading to the optimization of a critical SiNWs concentration. - Abstract: Hybrid thin films combining the high optical absorption of a semiconducting polymer film and the electronic properties of silicon fillers have been investigated in the perspective of the development of low cost solar cells. Bulk heterojunction photovoltaic materials based on blends of a semiconductor polymer poly(N-vinylcarbazole) (PVK) as electron donor and silicon nanowires (SiNWs) as electron acceptor have been studied. Composite PVK/SiNWs films were cast from a common solvent mixture. UV–visible spectrometry and photoluminescence of the composites have been studied as a function of the SiNWs concentration. Photoluminescence spectroscopy (PL) shows the existence of a critical SiNWs concentration of about 10 wt % for PL quenching corresponding to the most efficient charge pair separation. The photovoltaic (PV) effect has been studied under illumination. The optimum open-circuit voltage V oc and short-circuit current density J sc are obtained for 10 wt % SiNWs whereas a degradation of these parameters is observed at higher SiNWs concentrations. These results are correlated to the formation of aggregates in the composite leading to recombination of the photogenerated charge pairs competing with the dissociation mechanism.

Electron transport in silicon nanowires having different cross-sections

Directory of Open Access Journals (Sweden)

Muscato Orazio

2016-06-01

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

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

KAUST Repository

McDowell, Matthew T.

2011-09-14

With its high specific capacity, silicon is a promising anode material for high-energy lithium-ion batteries, but volume expansion and fracture during lithium reaction have prevented implementation. Si nanostructures have shown resistance to fracture during cycling, but the critical effects of nanostructure size and native surface oxide on volume expansion and cycling performance are not understood. Here, we use an ex situ transmission electron microscopy technique to observe the same Si nanowires before and after lithiation and have discovered the impacts of size and surface oxide on volume expansion. For nanowires with native SiO2, the surface oxide can suppress the volume expansion during lithiation for nanowires with diameters <∼50 nm. Finite element modeling shows that the oxide layer can induce compressive hydrostatic stress that could act to limit the extent of lithiation. The understanding developed herein of how volume expansion and extent of lithiation can depend on nanomaterial structure is important for the improvement of Si-based anodes. © 2011 American Chemical Society.

Porous Silicon-Based Biosensors: Towards Real-Time Optical Detection of Target Bacteria in the Food Industry.

Science.gov (United States)

Massad-Ivanir, Naama; Shtenberg, Giorgi; Raz, Nitzan; Gazenbeek, Christel; Budding, Dries; Bos, Martine P; Segal, Ester

2016-11-30

Rapid detection of target bacteria is crucial to provide a safe food supply and to prevent foodborne diseases. Herein, we present an optical biosensor for identification and quantification of Escherichia coli (E. coli, used as a model indicator bacteria species) in complex food industry process water. The biosensor is based on a nanostructured, oxidized porous silicon (PSi) thin film which is functionalized with specific antibodies against E. coli. The biosensors were exposed to water samples collected directly from process lines of fresh-cut produce and their reflectivity spectra were collected in real time. Process water were characterized by complex natural micro-flora (microbial load of >10 7  cell/mL), in addition to soil particles and plant cell debris. We show that process water spiked with culture-grown E. coli, induces robust and predictable changes in the thin-film optical interference spectrum of the biosensor. The latter is ascribed to highly specific capture of the target cells onto the biosensor surface, as confirmed by real-time polymerase chain reaction (PCR). The biosensors were capable of selectively identifying and quantifying the target cells, while the target cell concentration is orders of magnitude lower than that of other bacterial species, without any pre-enrichment or prior processing steps.

Tunable electronic properties of silicon nanowires under strain and electric bias

Directory of Open Access Journals (Sweden)

Alexis Nduwimana

2014-07-01

Full Text Available The electronic structure characteristics of silicon nanowires under strain and electric bias are studied using first-principles density functional theory. The unique wire-like structure leads to distinct spatial distribution of carriers, which can be tailored by applying tensile and compressive strains, as well as by an electric bias. Our results indicate that the combined effect of strain and electric bias leads to tunable electronic structures that can be used for piezo-electric devices.

Surface chemistry and morphology of the solid electrolyte interphase on silicon nanowire lithium-ion battery anodes

KAUST Repository

Chan, Candace K.; Ruffo, Riccardo; Hong, Seung Sae; Cui, Yi

2009-01-01

Silicon nanowires (SiNWs) have the potential to perform as anodes for lithium-ion batteries with a much higher energy density than graphite. However, there has been little work in understanding the surface chemistry of the solid electrolyte

Controlling growth density and patterning of single crystalline silicon nanowires

International Nuclear Information System (INIS)

Chang, Tung-Hao; Chang, Yu-Cheng; Liu, Fu-Ken; Chu, Tieh-Chi

2010-01-01

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

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.

Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method

KAUST Repository

Najar, Adel; Anjum, Dalaver H.; Hedhili, Mohamed N.; Ng, Tien Khee; Ooi, Boon S.; Ben Slimane, Ahmed; Sougrat, Rachid

2012-01-01

We report on the structural and optical properties of porous silicon nanowires (PSiNWs) fabricated using silver (Ag) ions assisted electroless etching method. Silicon nanocrystallites with sizes <5 nm embedded in amorphous silica have been

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.

Quantum efficiency of InAs/InP nanowire heterostructures grown on silicon substrates

International Nuclear Information System (INIS)

Anufriev, Roman; Chauvin, Nicolas; Bru-Chevallier, Catherine; Khmissi, Hammadi; Naji, Khalid; Gendry, Michel; Patriarche, Gilles

2013-01-01

Photoluminescence (PL) quantum efficiency (QE) is experimentally investigated, using an integrating sphere, as a function of excitation power on both InAs/InP quantum rod nanowires (QRod-NWs) and radial quantum well nanowires (QWell-NWs) grown on silicon substrates. The measured values of the QE are compared with those of the planar analogues such as quantum dash and quantum well samples, and found to be comparable for the quantum well structures at relatively low power density. Further studies reveal that the values of QE of the QRod-NWs and QWell-NWs are limited by the low quality of the InP NW structure and the quality of radial quantum well, respectively. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Optimization of silicon oxynitrides by plasma-enhanced chemical vapor deposition for an interferometric biosensor

Science.gov (United States)

Choo, Sung Joong; Lee, Byung-Chul; Lee, Sang-Myung; Park, Jung Ho; Shin, Hyun-Joon

2009-09-01

In this paper, silicon oxynitride layers deposited with different plasma-enhanced chemical vapor deposition (PECVD) conditions were fabricated and optimized, in order to make an interferometric sensor for detecting biochemical reactions. For the optimization of PECVD silicon oxynitride layers, the influence of the N2O/SiH4 gas flow ratio was investigated. RF power in the PEVCD process was also adjusted under the optimized N2O/SiH4 gas flow ratio. The optimized silicon oxynitride layer was deposited with 15 W in chamber under 25/150 sccm of N2O/SiH4 gas flow rates. The clad layer was deposited with 20 W in chamber under 400/150 sccm of N2O/SiH4 gas flow condition. An integrated Mach-Zehnder interferometric biosensor based on optical waveguide technology was fabricated under the optimized PECVD conditions. The adsorption reaction between bovine serum albumin (BSA) and the silicon oxynitride surface was performed and verified with this device.

Non-invasive, in vitro analysis of islet insulin production enabled by an optical porous silicon biosensor.

Science.gov (United States)

Chhasatia, Rinku; Sweetman, Martin J; Harding, Frances J; Waibel, Michaela; Kay, Tom; Thomas, Helen; Loudovaris, Thomas; Voelcker, Nicolas H

2017-05-15

A label-free porous silicon (pSi) based, optical biosensor, using both an antibody and aptamer bioreceptor motif has been developed for the detection of insulin. Two parallel biosensors were designed and optimised independently, based on each bioreceptor. Both bioreceptors were covalently attached to a thermally hydrosilylated pSi surface though amide coupling, with unreacted surface area rendered stable and low fouling by incorporation of PEG moieties. The insulin detection ability of each biosensor was determined using interferometric reflectance spectroscopy, using a range of different media both with and without serum. Sensing performance was compared in terms of response value, response time and limit of detection (LOD) for each platform. In order to demonstrate the capability of the best performing biosensor to detect insulin from real samples, an in vitro investigation with the aptamer-modified surface was performed. This biosensor was exposed to buffer conditioned by glucose-stimulated human islets, with the result showing a positive response and a high degree of selectivity towards insulin capture. The obtained results correlated well with the ELISA used in the clinic for assaying glucose-stimulated insulin release from donor islets. We anticipate that this type of sensor can be applied as a rapid point-of-use biosensor to assess the quality of donor islets in terms of their insulin production efficiency, prior to transplantation. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis, characterization and application of electroless metal assisted silicon nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Sahoo, Sumanta Kumar [Centre for Nanoscience & Technology, Department of Mechanical Engineering, Mepco Schlenk Engineering College, Sivakasi 626 005, Tamilnadu (India); Marikani, Arumugam, E-mail: amari@mepcoeng.ac.in [Department of Physics, Mepco Schlenk Engineering College, Sivakasi 626 005, Tamilnadu (India)

2015-12-01

Highlights: • Preparation of Silicon nanowire arrays (SiNWs) by electroless metal deposition technique. • From analysis, it has been found that the as-prepared SiNWs are of 3.5–4.0 μm and 75 nm of length and diameter in average respectively. Further a characteristic Raman peak at 520 cm{sup −1} also has been observed. • It exhibits good electron field-emission properties with turn-on field (E{sub 0}) of about 8.26 V μm{sup −1} at current density (J) of 4.9 μA cm{sup −2}. • Functionalized SiNWs have been used for electrochemical detection bovine serum albumin protein bio-molecules. - Abstract: Vertically aligned silicon nanowire arrays (SiNWs) have been synthesized by electroless metal deposition process. The fabricated SiNWs have an average diameter of 75 nm and 3.5–4.0 μm length, as confirmed from scanning electron microscopy. A characteristic asymmetric peak broadening at 520 cm{sup −1} from Raman spectroscopy was obtained for the SiNWs as compared to the bulk silicon crystal due to phonon confinement. The as-prepared SiNWs exhibit good electron field-emission properties with turn-on field of about 8.26 V μm{sup −1} at a current density of 4.9 μA cm{sup −2}. The SiNWs was functionalized by coating with a thin gold metallic film for 60 s, and then used as bio-probe for the detection of bovine serum albumin (BSA) protein molecules. From the linear sweep voltammetry analysis, the Au coated SiNWs, exhibit linear response to the BSA analyte with increase in concentration. The minimum detection limit of the protein molecule was calculated of about 1.16 μM by the as-synthesized SiNWs probe.

Fabrication of double-dot single-electron transistor in silicon nanowire

International Nuclear Information System (INIS)

Jo, Mingyu; Kaizawa, Takuya; Arita, Masashi; Fujiwara, Akira; Ono, Yukinori; Inokawa, Hiroshi; Choi, Jung-Bum; Takahashi, Yasuo

2010-01-01

We propose a simple method for fabricating Si single-electron transistors (SET) with coupled dots by means of a pattern-dependent-oxidation (PADOX) method. The PADOX method is known to convert a small one-dimensional Si wire formed on a silicon-on-insulator (SOI) substrate into a SET automatically. We fabricated a double-dot Si SET when we oxidized specially designed Si nanowires formed on SOI substrates. We analyzed the measured electrical characteristics by fitting the measurement and simulation results and confirmed the double-dot formation and the position of the two dots in the Si wire.

Electrochemically fabricated polyaniline nanowire-modified electrode for voltammetric detection of DNA hybridization

International Nuclear Information System (INIS)

Zhu Ningning; Chang Zhu; He Pingang; Fang Yuzhi

2006-01-01

A novel and sensitive electrochemical DNA biosensor based on electrochemically fabricated polyaniline nanowire and methylene blue for DNA hybridization detection is presented. Nanowires of conducting polymers were directly synthesized through a three-step electrochemical deposition procedure in an aniline-containing electrolyte solution, by using the glassy carbon electrode (GCE) as the working electrode. The morphology of the polyaniline films was examined using a field emission scanning electron microscope (SEM). The diameters of the nanowires range from 80 to 100 nm. The polyaniline nanowires-coated electrode exhibited very good electrochemical conductivity. Oligonucleotides with phosphate groups at the 5' end were covalently linked onto the amino groups of polyaniline nanowires on the electrode. The hybridization events were monitored with differential pulse voltammetry (DPV) measurement using methylene blue (MB) as an indicator. The approach described here can effectively discriminate complementary from non-complementary DNA sequence, with a detection limit of 1.0 x 10 -12 mol l -1 of complementary target, suggesting that the polyaniline nanowires hold great promises for sensitive electrochemical biosensor applications

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

Directory of Open Access Journals (Sweden)

P. Pignalosa

2011-09-01

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

Highly stable porous silicon-carbon composites as label-free optical biosensors.

Science.gov (United States)

Tsang, Chun Kwan; Kelly, Timothy L; Sailor, Michael J; Li, Yang Yang

2012-12-21

A stable, label-free optical biosensor based on a porous silicon-carbon (pSi-C) composite is demonstrated. The material is prepared by electrochemical anodization of crystalline Si in an HF-containing electrolyte to generate a porous Si template, followed by infiltration of poly(furfuryl) alcohol (PFA) and subsequent carbonization to generate the pSi-C composite as an optically smooth thin film. The pSi-C sensor is significantly more stable toward aqueous buffer solutions (pH 7.4 or 12) compared to thermally oxidized (in air, 800 °C), hydrosilylated (with undecylenic acid), or hydrocarbonized (with acetylene, 700 °C) porous Si samples prepared and tested under similar conditions. Aqueous stability of the pSi-C sensor is comparable to related optical biosensors based on porous TiO(2) or porous Al(2)O(3). Label-free optical interferometric biosensing with the pSi-C composite is demonstrated by detection of rabbit IgG on a protein-A-modified chip and confirmed with control experiments using chicken IgG (which shows no affinity for protein A). The pSi-C sensor binds significantly more of the protein A capture probe than porous TiO(2) or porous Al(2)O(3), and the sensitivity of the protein-A-modified pSi-C sensor to rabbit IgG is found to be ~2× greater than label-free optical biosensors constructed from these other two materials.

Pattern formation of nanoflowers during the vapor-liquid-solid growth of silicon nanowires

International Nuclear Information System (INIS)

Bae, Joonho; Thompson-Flagg, Rebecca; Ekerdt, John G.; Shih, C.-K.

2008-01-01

Pattern formation of nanoflowers during the vapor-liquid-solid growth of Si nanowires is reported. Using transmission electron microscopy, scanning electron microscopy, and energy dispersive spectrometer analysis, we show that the flower consists of an Au/SiO x core-shell structure. Moreover, the growth of flower starts at the interface between the gold catalyst and the silicon nanowire, presumably by enhanced oxidation at this interface. The pattern formation can be classified as dense branching morphology (DBM). It is the first observation of DBM in a spherical geometry and at the nanoscale. The analysis of the average branching distance of this pattern shows that the pattern is most likely formed during the growth process, not the cooling process, and that the curvature of the gold droplet plays a crucial role in the frequency of branching

Prelithiated Silicon Nanowires as an Anode for Lithium Ion Batteries

KAUST Repository

Liu, Nian

2011-08-23

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

Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

Science.gov (United States)

Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

2015-01-13

Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

Excitation of nanowire surface plasmons by silicon vacancy centers in nanodiamonds

DEFF Research Database (Denmark)

Kumar, Shailesh; Davydov, Valery A.; Agafonov, Viatcheslav N.

2017-01-01

Silicon vacancy (SiV) centers in diamonds have emerged as a very promising candidate for quantum emitters due to their narrow emission line resulting in their indistinguishability. While many different quantum emitters have already been used for the excitation of various propagating plasmonic modes......, the corresponding exploitation of SiV centers has remained so far uncharted territory. Here, we report on the excitation of surface plasmon modes supported by silver nanowires using SiV centers in nanodiamonds. The coupling of SiV center fluorescence to surface plasmons is observed, when a nanodiamond situated...

Silicon photonic resonator for label-free bio-sensing application

Science.gov (United States)

Udomsom, Suruk; Mankong, Ukrit; Theera-Umpon, Nipon; Ittipratheep, Nattapol; Umezawa, Toshimasa; Matsumoto, Atsushi; Yamamoto, Naokatsu

2018-03-01

In medical diagnostics there is an increasing demand for biosensors that can specifically detect biological analytes in a fluid. Especially label-free sensing, consistings of a transducer with biorecognition molecules immobilized on its surface without relying on fluorescent dye. In this paper we study the design and fabrication of a silicon nanowire photonic ring resonator and its feasibility as a biosensor. We have simulated and fabricated racetrack ring resonators which have a few tenths of micrometer gap, up to 0.5 μm between the input / output waveguides and the resonators. It is found that the devices can be designed with large Q factors. Sensitivity to biomaterial detection has been simulated for antibody (goat anti-mouse IgG) - antigen (mouse IgG) using 3-dimensional Finite Difference Time Domain technique. The simulated results show that the ring resonator has a response 15 nm resonance shift per refractive index unit. Antibody coating method is also discussed in this paper which can be applied to other antibody-antigen types.

Customization of Protein Single Nanowires for Optical Biosensing.

Science.gov (United States)

Sun, Yun-Lu; Sun, Si-Ming; Wang, Pan; Dong, Wen-Fei; Zhang, Lei; Xu, Bin-Bin; Chen, Qi-Dai; Tong, Li-Min; Sun, Hong-Bo

2015-06-24

An all-protein single-nanowire optical biosensor is constructed by a facile and general femtosecond laser direct writing approach with nanoscale structural customization. As-formed protein single nanowires show excellent optical properties (fine waveguiding performance and bio-applicable transmission windows), and are utilized as evanescent optical nanobiosensors for label-free biotin detection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved Ion-Channel Biosensors

Science.gov (United States)

Nadeau, Jay; White, Victor; Dougherty, Dennis; Maurer, Joshua

2004-01-01

An effort is underway to develop improved biosensors of a type based on ion channels in biomimetic membranes. These sensors are microfabricated from silicon and other materials compatible with silicon. As described, these sensors offer a number of advantages over prior sensors of this type.

Relaxing the electrostatic screening effect by patterning vertically-aligned silicon nanowire arrays into bundles for field emission application

Energy Technology Data Exchange (ETDEWEB)

Hung, Yung-Jr, E-mail: yungjrhung@gmail.com [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Department of Photonics, National Sun Yat-sen University, No. 70, Lienhai Rd., Kaohsiung 80424, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Lee, San-Liang [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Beng, Looi Choon [Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Chang, Hsuan-Chen [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Huang, Yung-Jui [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Lee, Kuei-Yi; Huang, Ying-Sheng [Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China); Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC (China)

2014-04-01

Top-down fabrication strategies are proposed and demonstrated to realize arrays of vertically-aligned silicon nanowire bundles and bundle arrays of carbon nanotube–silicon nanowire (CNT–SiNW) heterojunctions, aiming for releasing the electrostatic screening effect and improving the field emission characteristics. The trade-off between the reduction in the electrostatic screening effect and the decrease of emission sites leads to an optimal SiNW bundle arrangement which enables the lowest turn-on electric field of 1.4 V/μm and highest emission current density of 191 μA/cm{sup 2} among all testing SiNW samples. Benefiting from the superior thermal and electrical properties of CNTs and the flexible patterning technologies available for SiNWs, bundle arrays of CNT–SiNW heterojunctions show improved and highly-uniform field emission with a lower turn-on electric field of 0.9 V/μm and higher emission current density of 5.86 mA/cm{sup 2}. The application of these materials and their corresponding fabrication approaches is not limited to the field emission but can be used for a variety of emerging fields like nanoelectronics, lithium-ion batteries, and solar cells. - Highlights: • Aligned silicon nanowire (SiNW) bundle arrays are realized with top-down methods. • Growing carbon nanotubes atop SiNW bundle arrays enable uniform field emission. • A turn-on field of 0.9 V/μm and an emission current of > 5 mA/cm{sup 2} are achieved.

Silicon Wafer-Based Platinum Microelectrode Array Biosensor for Near Real-Time Measurement of Glutamate in Vivo

Directory of Open Access Journals (Sweden)

Nigel T. Maidment

2008-08-01

Full Text Available Using Micro-Electro-Mechanical-Systems (MEMS technologies, we have developed silicon wafer-based platinum microelectrode arrays (MEAs modified with glutamate oxidase (GluOx for electroenzymatic detection of glutamate in vivo. These MEAs were designed to have optimal spatial resolution for in vivo recordings. Selective detection of glutamate in the presence of the electroactive interferents, dopamine and ascorbic acid, was attained by deposition of polypyrrole and Nafion. The sensors responded to glutamate with a limit of detection under 1μM and a sub-1-second response time in solution. In addition to extensive in vitro characterization, the utility of these MEA glutamate biosensors was also established in vivo. In the anesthetized rat, these MEA glutamate biosensors were used for detection of cortically-evoked glutamate release in the ventral striatum. The MEA biosensors also were applied to the detection of stress-induced glutamate release in the dorsal striatum of the freely-moving rat.

Comparison of Light Trapping in Silicon Nanowire and Surface Textured Thin-Film Solar Cells

Directory of Open Access Journals (Sweden)

Rion Parsons

2017-04-01

Full Text Available The optics of axial silicon nanowire solar cells is investigated and compared to silicon thin-film solar cells with textured contact layers. The quantum efficiency and short circuit current density are calculated taking a device geometry into account, which can be fabricated by using standard semiconductor processing. The solar cells with textured absorber and textured contact layers provide a gain of short circuit current density of 4.4 mA/cm2 and 6.1 mA/cm2 compared to a solar cell on a flat substrate, respectively. The influence of the device dimensions on the quantum efficiency and short circuit current density will be discussed.

A sensitive DNA biosensor fabricated from gold nanoparticles, carbon nanotubes, and zinc oxide nanowires on a glassy carbon electrode

International Nuclear Information System (INIS)

Wang Jie; Li Shuping; Zhang Yuzhong

2010-01-01

We outline here the fabrication of a sensitive electrochemical DNA biosensor for the detection of sequence-specific target DNA. Zinc oxide nanowires (ZnONWs) were first immobilized on the surface of a glassy carbon electrode. Multi-walled carbon nanotubes (MWCNTs) with carboxyl groups were then dropped onto the surface of the ZnONWs. Gold nanoparticles (AuNPs) were subsequently introduced to the surface of the MWNTs/ZnONWs by electrochemical deposition. A single-stranded DNA probe with a thiol group at the end (HS-ssDNA) was covalently immobilized on the surface of the AuNPs by forming an Au-S bond. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) were used to investigate the film assembly process. Differential pulse voltammetry (DPV) was used to monitor DNA hybridization by measuring the electrochemical signals of [Ru(NH 3 ) 6 ] 3+ bounding to double-stranded DNA (dsDNA). The incorporation of ZnONWs and MWCNTs in this sensor design significantly enhances the sensitivity and the selectivity. This DNA biosensor can detect the target DNA quantitatively in the range of 1.0 x 10 -13 to 1.0 x 10 -7 M, with a detection limit of 3.5 x 10 -14 M (S/N = 3). In addition, the DNA biosensor exhibits excellent selectivity, even for single-mismatched DNA detection.

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.

Synthesis and characterization of porous silicon-based bio-sensors

International Nuclear Information System (INIS)

Naddaf, M.; AlMariry, A.

2015-01-01

The efficiency of porous silicon (Ps) as a platform for immobilization of biological molecules has been investigated. ps samples were prepared by electrochemical etching o both n and p- type crystalline silicon surfaces in a suitable electrolyte. Biotin anti-human IL-6; rat IgG2a antibody was chosen as biological element and the process of its immobilization onto ps surfaces was carried out via physical absorption process. Chemical surface characterization by means of fourier transformation infrared (FTIR) absorption spectroscopy, contact angle measurements and x-ray photoelectron spectroscopy (XPS) confirmed the efficiency of PS as entrapping template for the specific immobilization of IgG 2a antibody via physical absorption process. the antibody presence was detected by monitoring both the C Is and N Is sing nals in XPS spectra and amide i absorption band in the FTIR spectra of immobilized PS layer. these findings were also supported by photoluminescence (PL) spectroscopy which showed significant reduction in the PL peak intensity by the presence of the antibody. the PL quenching was utilized as an indicator for sensing the effect of ph of antibody solution on immobilization process the efficiency of PS as interferometric biosensor has been also demonstrated. (author)

Analytical Model of Subthreshold Drain Current Characteristics of Ballistic Silicon Nanowire Transistors

Directory of Open Access Journals (Sweden)

Wanjie Xu

2015-01-01

Full Text Available A physically based subthreshold current model for silicon nanowire transistors working in the ballistic regime is developed. Based on the electric potential distribution obtained from a 2D Poisson equation and by performing some perturbation approximations for subband energy levels, an analytical model for the subthreshold drain current is obtained. The model is further used for predicting the subthreshold slopes and threshold voltages of the transistors. Our results agree well with TCAD simulation with different geometries and under different biasing conditions.

Carrier dynamics in silicon nanowires studied using optical-pump terahertz-probe spectroscopy

Science.gov (United States)

Beaudoin, Alexandre; Salem, Bassem; Baron, Thierry; Gentile, Pascal; Morris, Denis

2014-03-01

The advance of non-contact measurements involving pulsed terahertz radiation presents great interests for characterizing electrical properties of a large ensemble of nanowires. In this work, N-doped and undoped silicon nanowires (SiNWs) grown by chemical vapour deposition (CVD) on quartz substrate were characterized using optical-pump terahertz probe (OPTP) transmission experiments. Our results show that defects and ionized impurities introduced by N-doping the CVD-grown SiNWs tend to reduce the photoexcited carrier lifetime and degrade their conductivity properties. Capture mechanisms by the surface trap states play a key role on the photocarrier dynamics in theses small diameters' (~100 nm) SiNWs and the doping level is found to alter this dynamics. We propose convincing capture and recombination scenarios that explain our OPTP measurements. Fits of our photoconductivity data curves, from 0.5 to 2 THz, using a Drude-plasmon conductivity model allow determining photocarrier mobility values of 190 and 70 cm2/V .s, for the undoped and N-doped NWs samples, respectively.

Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

International Nuclear Information System (INIS)

Yan, Hai; Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

2015-01-01

A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed

Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

Energy Technology Data Exchange (ETDEWEB)

Yan, Hai, E-mail: hai.yan@utexas.edu; Zou, Yi; Yang, Chun-Ju [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Chakravarty, Swapnajit, E-mail: swapnajit.chakravarty@omegaoptics.com [Omega Optics, Inc., 8500 Shoal Creek Blvd., Austin, Texas 78757 (United States); Wang, Zheng [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States); Tang, Naimei; Chen, Ray T., E-mail: raychen@uts.cc.utexas.edu [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Omega Optics, Inc., 8500 Shoal Creek Blvd., Austin, Texas 78757 (United States); Fan, Donglei [Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)

2015-03-23

A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

Horizontal silicon nanowires for surface-enhanced Raman spectroscopy

Science.gov (United States)

Gebavi, Hrvoje; Ristić, Davor; Baran, Nikola; Mikac, Lara; Mohaček-Grošev, Vlasta; Gotić, Marijan; Šikić, Mile; Ivanda, Mile

2018-01-01

The main purpose of this paper is to focus on details of the fabrication process of horizontally and vertically oriented silicon nanowires (SiNWs) substrates for the application of surface-enhanced Raman spectroscopy (SERS). The fabrication process is based on the vapor-liquid-solid method and electroless-assisted chemical etching, which, as the major benefit, resulting in the development of economical, easy-to-prepare SERS substrates. Furthermore, we examined the fabrication of Au coated Ag nanoparticles (NPs) on the SiNWs substrates in such a way as to diminish the influence of silver NPs corrosion, which, in turn, enhanced the SERS time stability, thus allowing for wider commercial applications. The substances on which high SERS sensitivity was proved are rhodamine (R6G) and 4-mercaptobenzoic acid (MBA), with the detection limits of 10-8 M and 10-6 M, respectively.

Rare earth silicide nanowires on silicon surfaces

International Nuclear Information System (INIS)

Wanke, Martina

2008-01-01

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

Energy transfer in nanowire solar cells with photon-harvesting shells

KAUST Repository

Peters, C. H.; Guichard, A. R.; Hryciw, A. C.; Brongersma, M. L.; McGehee, M. D.

2009-01-01

The concept of a nanowire solar cell with photon-harvesting shells is presented. In this architecture, organic molecules which absorb strongly in the near infrared where silicon absorbs weakly are coupled to silicon nanowires (SiNWs). This enables

Optical absorption enhancement in silicon nanowire arrays with a large lattice constant for photovoltaic applications.

Science.gov (United States)

Lin, Chenxi; Povinelli, Michelle L

2009-10-26

In this paper, we use the transfer matrix method to calculate the optical absorptance of vertically-aligned silicon nanowire (SiNW) arrays. For fixed filling ratio, significant optical absorption enhancement occurs when the lattice constant is increased from 100 nm to 600 nm. The enhancement arises from an increase in field concentration within the nanowire as well as excitation of guided resonance modes. We quantify the absorption enhancement in terms of ultimate efficiency. Results show that an optimized SiNW array with lattice constant of 600 nm and wire diameter of 540 nm has a 72.4% higher ultimate efficiency than a Si thin film of equal thickness. The enhancement effect can be maintained over a large range of incidence angles.

Silicon based ultrafast optical waveform sampling

DEFF Research Database (Denmark)

Ji, Hua; Galili, Michael; Pu, Minhao

2010-01-01

A 300 nmx450 nmx5 mm silicon nanowire is designed and fabricated for a four wave mixing based non-linear optical gate. Based on this silicon nanowire, an ultra-fast optical sampling system is successfully demonstrated using a free-running fiber laser with a carbon nanotube-based mode-locker as th......A 300 nmx450 nmx5 mm silicon nanowire is designed and fabricated for a four wave mixing based non-linear optical gate. Based on this silicon nanowire, an ultra-fast optical sampling system is successfully demonstrated using a free-running fiber laser with a carbon nanotube-based mode......-locker as the sampling source. A clear eye-diagram of a 320 Gbit/s data signal is obtained. The temporal resolution of the sampling system is estimated to 360 fs....

Rare earth silicide nanowires on silicon surfaces

Energy Technology Data Exchange (ETDEWEB)

Wanke, Martina

2008-11-10

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

Surface effects on the thermal conductivity of silicon nanowires

Science.gov (United States)

Li, Hai-Peng; Zhang, Rui-Qin

2018-03-01

Thermal transport in silicon nanowires (SiNWs) has recently attracted considerable attention due to their potential applications in energy harvesting and generation and thermal management. The adjustment of the thermal conductivity of SiNWs through surface effects is a topic worthy of focus. In this paper, we briefly review the recent progress made in this field through theoretical calculations and experiments. We come to the conclusion that surface engineering methods are feasible and effective methods for adjusting nanoscale thermal transport and may foster further advancements in this field. Project supported by the National Natural Science Foundation ofChina (Grant No. 11504418), China Scholarship Council (Grant No. 201706425053), Basic Research Program in Shenzhen, China (Grant No. JCYJ20160229165210666), and the Fundamental Research Funds for the Central Universities of China (Grant No. 2015XKMS075).

Fabrication of porous silicon nanowires by MACE method in HF/H2O2/AgNO3 system at room temperature

Science.gov (United States)

2014-01-01

In this paper, the moderately and lightly doped porous silicon nanowires (PSiNWs) were fabricated by the ‘one-pot procedure’ metal-assisted chemical etching (MACE) method in the HF/H2O2/AgNO3 system at room temperature. The effects of H2O2 concentration on the nanostructure of silicon nanowires (SiNWs) were investigated. The experimental results indicate that porous structure can be introduced by the addition of H2O2 and the pore structure could be controlled by adjusting the concentration of H2O2. The H2O2 species replaces Ag+ as the oxidant and the Ag nanoparticles work as catalyst during the etching. And the concentration of H2O2 influences the nucleation and motility of Ag particles, which leads to formation of different porous structure within the nanowires. A mechanism based on the lateral etching which is catalyzed by Ag particles under the motivation by H2O2 reduction is proposed to explain the PSiNWs formation. PMID:24910568

Metallization of DNA on silicon surface

International Nuclear Information System (INIS)

Puchkova, Anastasiya Olegovna; Sokolov, Petr; Petrov, Yuri Vladimirovich; Kasyanenko, Nina Anatolievna

2011-01-01

New simple way for silver deoxyribonucleic acid (DNA)-based nanowires preparation on silicon surface was developed. The electrochemical reduction of silver ions fixed on DNA molecule provides the forming of tightly matched zonate silver clusters. Highly homogeneous metallic clusters have a size about 30 nm. So the thickness of nanowires does not exceed 30–50 nm. The surface of n-type silicon monocrystal is the most convenient substrate for this procedure. The comparative analysis of DNA metallization on of n-type silicon with a similar way for nanowires fabrication on p-type silicon, freshly cleaved mica, and glass surface shows the advantage of n-type silicon, which is not only the substrate for DNA fixation but also the source of electrons for silver reduction. Images of bound DNA molecules and fabricated nanowires have been obtained using an atomic force microscope and a scanning ion helium microscope. DNA interaction with silver ions in a solution was examined by the methods of ultraviolet spectroscopy and circular dichroism.

Microcantilever equipped with nanowire template electrodes for multiprobe measurement on fragile nanostructures

DEFF Research Database (Denmark)

Lin, Rong; Bøggild, Peter; Hansen, Ole

2004-01-01

cantilevers. By subsequently covering these nanowires with a metallic coating, they are made conducting and at the same time fixed to the cantilevers. These silicon nanowire four-point probes were tested on 7 and 35 nm thick Au films as well as poorly adhering 16 nm thin Au nanowires deposited on a silicon...

Tunneling magnetoresistance in Si nanowires

KAUST Repository

Montes Muñoz, Enrique

2016-11-09

We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

Tunneling magnetoresistance in Si nanowires

KAUST Repository

Montes Muñ oz, Enrique; Rungger, I.; Sanvito, S.; Schwingenschlö gl, Udo

2016-01-01

for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we

Extended vapor-liquid-solid growth of silicon carbide nanowires.

Science.gov (United States)

Rajesh, John Anthuvan; Pandurangan, Arumugam

2014-04-01

We developed an alloy catalytic method to explain extended vapor-liquid-solid (VLS) growth of silicon carbide nanowires (SiC NWs) by a simple thermal evaporation of silicon and activated carbon mixture using lanthanum nickel (LaNi5) alloy as catalyst in a chemical vapor deposition process. The LaNi5 alloy binary phase diagram and the phase relationships in the La-Ni-Si ternary system were play a key role to determine the growth parameters in this VLS mechanism. Different reaction temperatures (1300, 1350 and 1400 degrees C) were applied to prove the established growth process by experimentally. Scanning electron microscopy and transmission electron microscopy studies show that the crystalline quality of the SiC NWs increases with the temperature at which they have been synthesized. La-Ni alloyed catalyst particles observed on the top of the SiC NWs confirms that the growth process follows this extended VLS mechanism. The X-ray diffraction and confocal Raman spectroscopy analyses demonstrate that the crystalline structure of the SiC NWs was zinc blende 3C-SiC. Optical property of the SiC NWs was investigated by photoluminescence technique at room temperature. Such a new alloy catalytic method may be extended to synthesis other one-dimensional nanostructures.

Towards the Development of Electrical Biosensors Based on Nanostructured Porous Silicon

Science.gov (United States)

Recio-Sánchez, Gonzalo; Torres-Costa, Vicente; Manso, Miguel; Gallach, Darío; López-García, Juan; Martín-Palma, Raúl J.

2010-01-01

The typical large specific surface area and high reactivity of nanostructured porous silicon (nanoPS) make this material very suitable for the development of sensors. Moreover, its biocompatibility and biodegradability opens the way to the development of biosensors. As such, in this work the use of nanoPS in the field of electrical biosensing is explored. More specifically, nanoPS-based devices with Al/nanoPS/Al and Au-NiCr/nanoPS/Au-NiCr structures were fabricated for the electrical detection of glucose and Escherichia Coli bacteria at different concentrations. The experimental results show that the current-voltage characteristics of these symmetric metal/nanoPS/metal structures strongly depend on the presence/absence and concentration of species immobilized on the surface.

Towards the Development of Electrical Biosensors Based on Nanostructured Porous Silicon

Directory of Open Access Journals (Sweden)

Raúl J. Martín-Palma

2010-01-01

Full Text Available The typical large specific surface area and high reactivity of nanostructured porous silicon (nanoPS make this material very suitable for the development of sensors. Moreover, its biocompatibility and biodegradability opens the way to the development of biosensors. As such, in this work the use of nanoPS in the field of electrical biosensing is explored. More specifically, nanoPS-based devices with Al/nanoPS/Al and Au-NiCr/nanoPS/Au-NiCr structures were fabricated for the electrical detection of glucose and Escherichia Coli bacteria at different concentrations. The experimental results show that the current-voltage characteristics of these symmetric metal/nanoPS/metal structures strongly depend on the presence/absence and concentration of species immobilized on the surface.

The SERS and TERS effects obtained by gold droplets on top of Si nanowires.

Science.gov (United States)

Becker, M; Sivakov, V; Andrä, G; Geiger, R; Schreiber, J; Hoffmann, S; Michler, J; Milenin, A P; Werner, P; Christiansen, S H

2007-01-01

We show that hemispherical gold droplets on top of silicon nanowires when grown by the vapor-liquid-solid (VLS) mechanism, can produce a significant enhancement of Raman scattered signals. Signal enhancement for a few or even just single gold droplets is demonstrated by analyzing the enhanced Raman signature of malachite green molecules. For this experiment, trenches (approximately 800 nm wide) were etched in a silicon-on-insulator (SOI) wafer along crystallographic directions that constitute sidewalls ({110} surfaces) suitable for the growth of silicon nanowires in directions with the intention that the gold droplets on the silicon nanowires can meet somewhere in the trench when growth time is carefully selected. Another way to realize gold nanostructures in close vicinity is to attach a silicon nanowire with a gold droplet onto an atomic force microscopy (AFM) tip and to bring this tip toward another gold-coated AFM tip where malachite green molecules were deposited prior to the measurements. In both experiments, signal enhancement of characteristic Raman bands of malachite green molecules was observed. This indicates that silicon nanowires with gold droplets atop can act as efficient probes for tip-enhanced Raman spectroscopy (TERS). In our article, we show that a nanowire TERS probe can be fabricated by welding nanowires with gold droplets to AFM tips in a scanning electron microscope (SEM). TERS tips made from nanowires could improve the spatial resolution of Raman spectroscopy so that measurements on the nanometer scale are possible.

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.

Large-Scale Fabrication of Silicon Nanowires for Solar Energy Applications.

Science.gov (United States)

Zhang, Bingchang; Jie, Jiansheng; Zhang, Xiujuan; Ou, Xuemei; Zhang, Xiaohong

2017-10-11

The development of silicon (Si) materials during past decades has boosted up the prosperity of the modern semiconductor industry. In comparison with the bulk-Si materials, Si nanowires (SiNWs) possess superior structural, optical, and electrical properties and have attracted increasing attention in solar energy applications. To achieve the practical applications of SiNWs, both large-scale synthesis of SiNWs at low cost and rational design of energy conversion devices with high efficiency are the prerequisite. This review focuses on the recent progresses in large-scale production of SiNWs, as well as the construction of high-efficiency SiNW-based solar energy conversion devices, including photovoltaic devices and photo-electrochemical cells. Finally, the outlook and challenges in this emerging field are presented.

Recent Advances on Luminescent Enhancement-Based Porous Silicon Biosensors.

Science.gov (United States)

Jenie, S N Aisyiyah; Plush, Sally E; Voelcker, Nicolas H

2016-10-01

Luminescence-based detection paradigms have key advantages over other optical platforms such as absorbance, reflectance or interferometric based detection. However, autofluorescence, low quantum yield and lack of photostability of the fluorophore or emitting molecule are still performance-limiting factors. Recent research has shown the need for enhanced luminescence-based detection to overcome these drawbacks while at the same time improving the sensitivity, selectivity and reducing the detection limits of optical sensors and biosensors. Nanostructures have been reported to significantly improve the spectral properties of the emitting molecules. These structures offer unique electrical, optic and magnetic properties which may be used to tailor the surrounding electrical field of the emitter. Here, the main principles behind luminescence and luminescence enhancement-based detections are reviewed, with an emphasis on europium complexes as the emitting molecule. An overview of the optical porous silicon microcavity (pSiMC) as a biosensing platform and recent proof-of-concept examples on enhanced luminescence-based detection using pSiMCs are provided and discussed.

Hydrogenated amorphous silicon nitride photonic crystals for improved-performance surface electromagnetic wave biosensors.

Science.gov (United States)

Sinibaldi, Alberto; Descrovi, Emiliano; Giorgis, Fabrizio; Dominici, Lorenzo; Ballarini, Mirko; Mandracci, Pietro; Danz, Norbert; Michelotti, Francesco

2012-10-01

We exploit the properties of surface electromagnetic waves propagating at the surface of finite one dimensional photonic crystals to improve the performance of optical biosensors with respect to the standard surface plasmon resonance approach. We demonstrate that the hydrogenated amorphous silicon nitride technology is a versatile platform for fabricating one dimensional photonic crystals with any desirable design and operating in a wide wavelength range, from the visible to the near infrared. We prepared sensors based on photonic crystals sustaining either guided modes or surface electromagnetic waves, also known as Bloch surface waves. We carried out for the first time a direct experimental comparison of their sensitivity and figure of merit with surface plasmon polaritons on metal layers, by making use of a commercial surface plasmon resonance instrument that was slightly adapted for the experiments. Our measurements demonstrate that the Bloch surface waves on silicon nitride photonic crystals outperform surface plasmon polaritons by a factor 1.3 in terms of figure of merit.

Collective behaviors of mammalian cells on amine-coated silicon nanowires

International Nuclear Information System (INIS)

Kim, So Yeon; Yang, Eun Gyeong

2013-01-01

Intensive studies with vertical nanowire (NW) arrays have illustrated broad implications for manipulating mammalian cells in vitro, but how cellular responses are influenced by the presence of NWs has not been thoroughly investigated. Here, we address collective cellular behaviors, including surface area of cells, membrane trafficking, focal adhesion distribution and dynamics, and cytoskeletal protein distribution on amine-coated silicon (Si) NWs with different physical properties. The degree of HeLa cell spreading was inversely proportional to the surface area occupied by the NWs, which was not affected by manipulation of membrane trafficking dynamics. In the presence of a diffusive focal complex around the NWs, strong, well organized focal adhesion was hardly visible on the NWs, implying that the cells were interacting weakly with the NW-embedded surface. Furthermore, we found that actin filament formation of the cells on long NWs was not favorable, and this could explain our observation of reduced cell spreading, as well as the decreased number of focal adhesion complexes. Taken together, our results suggest that cells can survive on silicon NWs by adjusting their morphology and adhesion behavior through actively organizing these molecules. (paper)

Organophosphonate-based PNA-functionalization of silicon nanowires for label-free DNA detection.

Science.gov (United States)

Cattani-Scholz, Anna; Pedone, Daniel; Dubey, Manish; Neppl, Stefan; Nickel, Bert; Feulner, Peter; Schwartz, Jeffrey; Abstreiter, Gerhard; Tornow, Marc

2008-08-01

We investigated hydroxyalkylphosphonate monolayers as a novel platform for the biofunctionalization of silicon-based field effect sensor devices. This included a detailed study of the thin film properties of organophosphonate films on Si substrates using several surface analysis techniques, including AFM, ellipsometry, contact angle, X-ray photoelectron spectroscopy (XPS), X-ray reflectivity, and current-voltage characteristics in electrolyte solution. Our results indicate the formation of a dense monolayer on the native silicon oxide that has excellent passivation properties. The monolayer was biofunctionalized with 12 mer peptide nucleic acid (PNA) receptor molecules in a two-step procedure using the heterobifunctional linker, 3-maleimidopropionic-acid-N-hydroxysuccinimidester. Successful surface modification with the probe PNA was verified by XPS and contact angle measurements, and hybridization with DNA was determined by fluorescence measurements. Finally, the PNA functionalization protocol was translated to 2 microm long, 100 nm wide Si nanowire field effect devices, which were successfully used for label-free DNA/PNA hybridization detection.

The antimicrobial effect of silicon nanowires decorated with silver and copper nanoparticles

International Nuclear Information System (INIS)

Fellahi, Ouarda; Marcon, Lionel; Coffinier, Yannick; Boukherroub, Rabah; Sarma, Rupak K; Saikia, Ratul; Das, Manash R; Hadjersi, Toufik; Maamache, Mustapha

2013-01-01

The paper reports on the preparation and antibacterial activity of silicon nanowire (SiNW) substrates coated with Ag or Cu nanoparticles (NPs) against Escherichia coli (E. coli) bacteria. The substrates are easily prepared using the metal-assisted chemical etching of crystalline silicon in hydrofluoric acid/silver nitrate (HF/AgNO 3 ) aqueous solution. Decoration of the SiNWs with metal NPs is achieved by simple immersion in HF aqueous solutions containing silver or copper salts. The SiNWs coated with Ag NPs are biocompatible with human lung adenocarcinoma epithelial cell line A549 while possessing strong antibacterial properties to E. coli. In contrast, the SiNWs decorated with Cu NPs showed higher cytotoxicity and slightly lower antibacterial activity. Moreover, it was also observed that leakage of sugars and proteins from the cell wall of E. coli in interaction with SiNWs decorated with Ag NPs is higher compared to SiNWs modified with Cu NPs. (paper)

Modification of polypyrrole nanowires array with platinum nanoparticles and glucose oxidase for fabrication of a novel glucose biosensor

Energy Technology Data Exchange (ETDEWEB)

Xu Guangqing [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Churchill, Victoria 3842 (Australia); School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Adeloju, Samuel B., E-mail: Sam.Adeloju@monash.edu [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Churchill, Victoria 3842 (Australia); Wu Yucheng [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang Xinyi [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Churchill, Victoria 3842 (Australia)

2012-11-28

Highlights: Black-Right-Pointing-Pointer Fabrication of well aligned PPyNWA of 20 nm diameter within AAO template. Black-Right-Pointing-Pointer Improvement of electrochemical properties by decoration with PtNPs. Black-Right-Pointing-Pointer Sensitive amperometric and potentiometric detection of glucose by adsorption of GOx on PPyNWA-PtNPs. Black-Right-Pointing-Pointer Detection of as little as 5.6 {mu}M glucose with potentiometric detection. Black-Right-Pointing-Pointer Comparable or better detection limit and sensitivity than some glucose biosensors fabricated with nanomaterials. - Abstract: A novel glucose biosensor, based on the modification of well-aligned polypyrrole nanowires array (PPyNWA) with Pt nanoparticles (PtNPs) and subsequent surface adsorption of glucose oxidase (GOx), is described. The distinct differences in the electrochemical properties of PPyNWA-GOx, PPyNWA-PtNPs, and PPyNWA-PtNPs-GOx electrodes were revealed by cyclic voltammetry. In particular, the results obtained for PPyNWA-PtNPs-GOx biosensor showed evidence of direct electron transfer due mainly to modification with PtNPs. Optimum fabrication of the PPyNWA-PtNPs-GOx biosensor for both potentiometric and amperometric detection of glucose were achieved with 0.2 M pyrrole, applied current density of 0.1 mA cm{sup -2}, polymerization time of 600 s, cyclic deposition of PtNPs from -200 mV to 200 mV, scan rate of 50 mV s{sup -1}, and 20 cycles. A sensitivity of 40.5 mV/decade and a linear range of 10 {mu}M to 1000 {mu}M (R{sup 2} = 0.9936) were achieved for potentiometric detection, while for amperometric detection a sensitivity of 34.7 {mu}A cm{sup -2} mM{sup -1} at an applied potential of 700 mV and a linear range of 0.1-9 mM (R{sup 2} = 0.9977) were achieved. In terms of achievable detection limit, potentiometric detection achieved 5.6 {mu}M of glucose, while amperometric detection achieved 27.7 {mu}M.

Modification of polypyrrole nanowires array with platinum nanoparticles and glucose oxidase for fabrication of a novel glucose biosensor

International Nuclear Information System (INIS)

Xu Guangqing; Adeloju, Samuel B.; Wu Yucheng; Zhang Xinyi

2012-01-01

Highlights: ► Fabrication of well aligned PPyNWA of 20 nm diameter within AAO template. ► Improvement of electrochemical properties by decoration with PtNPs. ► Sensitive amperometric and potentiometric detection of glucose by adsorption of GOx on PPyNWA–PtNPs. ► Detection of as little as 5.6 μM glucose with potentiometric detection. ► Comparable or better detection limit and sensitivity than some glucose biosensors fabricated with nanomaterials. - Abstract: A novel glucose biosensor, based on the modification of well-aligned polypyrrole nanowires array (PPyNWA) with Pt nanoparticles (PtNPs) and subsequent surface adsorption of glucose oxidase (GOx), is described. The distinct differences in the electrochemical properties of PPyNWA–GOx, PPyNWA–PtNPs, and PPyNWA–PtNPs–GOx electrodes were revealed by cyclic voltammetry. In particular, the results obtained for PPyNWA–PtNPs–GOx biosensor showed evidence of direct electron transfer due mainly to modification with PtNPs. Optimum fabrication of the PPyNWA–PtNPs–GOx biosensor for both potentiometric and amperometric detection of glucose were achieved with 0.2 M pyrrole, applied current density of 0.1 mA cm −2 , polymerization time of 600 s, cyclic deposition of PtNPs from −200 mV to 200 mV, scan rate of 50 mV s −1 , and 20 cycles. A sensitivity of 40.5 mV/decade and a linear range of 10 μM to 1000 μM (R 2 = 0.9936) were achieved for potentiometric detection, while for amperometric detection a sensitivity of 34.7 μA cm −2 mM −1 at an applied potential of 700 mV and a linear range of 0.1–9 mM (R 2 = 0.9977) were achieved. In terms of achievable detection limit, potentiometric detection achieved 5.6 μM of glucose, while amperometric detection achieved 27.7 μM.

Fluorinion transfer in silver-assisted chemical etching for silicon nanowires arrays

Science.gov (United States)

Feng, Tianyu; Xu, Youlong; Zhang, Zhengwei; Mao, Shengchun

2015-08-01

Uniform silicon nanowires arrays (SiNWAs) were fabricated on unpolished rough silicon wafers through KOH pretreatment followed by silver-assisted chemical etching (SACE). Density functional theory (DFT) calculations were used to investigate the function of silver (Ag) at atomic scale in the etching process. Among three adsorption sites of Ag atom on Si(1 0 0) surface, Ag(T4) above the fourth-layer surface Si atoms could transfer fluorinion (F-) to adjacent Si successfully due to its stronger electrostatic attraction force between Ag(T4) and F-, smaller azimuth angle of Fsbnd Ag(T4)sbnd Si, shorter bond length of Fsbnd Si compared with Fsbnd Ag. As F- was transferred to adjacent Si by Ag(T4) one by one, the Si got away from the wafer in the form of SiF4 when it bonded with enough F- while Ag(T4) was still attached onto the Si wafer ready for next transfer. Cyclic voltammetry tests confirmed that Ag can improve the etching rate by transferring F- to Si.

Si nanoparticle-decorated Si nanowire networks for Li-ion battery anodes

KAUST Repository

Hu, Liangbing

2011-01-01

We designed and fabricated binder-free, 3D porous silicon nanostructures for Li-ion battery anodes, where Si nanoparticles electrically contact current collectors via vertically grown silicon nanowires. When compared with a Si nanowire anode, the areal capacity was increased by a factor of 4 without having to use long, high temperature steps under vacuum that vapour-liquid-solid Si nanowire growth entails. © 2011 The Royal Society of Chemistry.

Small signal modulation characteristics of red-emitting (λ = 610 nm) III-nitride nanowire array lasers on (001) silicon

KAUST Repository

Jahangir, Shafat; Frost, Thomas; Hazari, Arnab; Yan, Lifan; Stark, Ethan; LaMountain, Trevor; Millunchick, Joanna M.; Ooi, Boon S.; Bhattacharya, Pallab

2015-01-01

The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and α-parameter, and large differential gain (3.1 × 10-17 cm2).

Small signal modulation characteristics of red-emitting (λ = 610 nm) III-nitride nanowire array lasers on (001) silicon

KAUST Repository

Jahangir, Shafat

2015-02-16

The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and α-parameter, and large differential gain (3.1 × 10-17 cm2).

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.

CONDUCTING-POLYMER NANOWIRE IMMUNOSENSOR ARRAYS FOR MICROBIAL PATHOGENS

Science.gov (United States)

The lack of methods for routine rapid and sensitive detection and quantification of specific pathogens has limited the amount of information available on their occurrence in drinking water and other environmental samples. The nanowire biosensor arrays developed in this study w...

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

KAUST Repository

Misra, Sumohan

2012-06-26

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

Twins and strain relaxation in zinc-blende GaAs nanowires grown on silicon

Energy Technology Data Exchange (ETDEWEB)

Piñero, J.C., E-mail: josecarlos.pinero@uca.es [Dpto. Ciencias de los Materiales, Universidad de Cádiz, 11510, Puerto Real, Cádiz (Spain); Araújo, D.; Pastore, C.E.; Gutierrez, M. [Dpto. Ciencias de los Materiales, Universidad de Cádiz, 11510, Puerto Real, Cádiz (Spain); Frigeri, C. [Istituto CNR-IMEM Parco Area delle Scienze 37/A, Fontanini, 43010, Parma (Italy); Benali, A.; Lelièvre, J.F.; Gendry, M. [INL-Institut des Nanotechnologies de Lyon, UMR 5270 Ecole Centrale de Lyon 36, Avenue Guy de Collongue, 69134, Ecully Cedex (France)

2017-02-15

Highlights: • A TEM-HREM study of GaAs nanowires, growth over Si, is presented. • Misfit dislocations are detected in the Si/GaAs magma interface. • The study demonstrates strain relaxation through twin formation in some nanowires. - Abstract: To integrate materials with large lattice mismatch as GaAs on silicon (Si) substrate, one possible approach, to improve the GaAs crystalline quality, is to use nanowires (NWs) technology. In the present contribution, NWs are grown on <111> oriented Si substrates by molecular beam epitaxy (MBE) using vapor-liquid-solid (VLS) method. Transmission electron microscopy (TEM) analyses show that NWs are mainly grown alternating wurtzite and zinc blend (ZB) phases, and only few are purely ZB. On the latter, High Resolution Electron Microscopy (HREM) evidences the presence of twins near the surface of the NW showing limited concordance with the calculations of Yuan (2013) [1], where {111} twin planes in a <111>-oriented GaAs NW attain attractive interactions mediated by surface strain. In addition, such twins allow slight strain relaxation and are probably induced by the local huge elastic strain observed by HREM in the lattice between the twin and the surface. The latter is attributed to some slight bending of the NW as shown by the inversion of the strain from one side to the other side of the NW.

Energy transfer in nanowire solar cells with photon-harvesting shells

KAUST Repository

Peters, C. H.

2009-01-01

The concept of a nanowire solar cell with photon-harvesting shells is presented. In this architecture, organic molecules which absorb strongly in the near infrared where silicon absorbs weakly are coupled to silicon nanowires (SiNWs). This enables an array of 7-μm -long nanowires with a diameter of 50 nm to absorb over 85% of the photons above the bandgap of silicon. The organic molecules are bonded to the surface of the SiNWs forming a thin shell. They absorb the low-energy photons and subsequently transfer the energy to the SiNWs via Förster resonant energy transfer, creating free electrons and holes within the SiNWs. The carriers are then separated at a radial p-n junction in a nanowire and extracted at the respective electrodes. The shortness of the nanowires is expected to lower the dark current due to the decrease in p-n junction surface area, which scales linearly with wire length. The theoretical power conversion efficiency is 15%. To demonstrate this concept, we measure a 60% increase in photocurrent from a planar silicon-on-insulator diode when a 5 nm layer of poly[2-methoxy-5-(2′ -ethyl-hexyloxy)-1,4-phenylene vinylene is applied to the surface of the silicon. This increase is in excellent agreement with theoretical predictions. © 2009 American Institute of Physics.

Fluorinion transfer in silver-assisted chemical etching for silicon nanowires arrays

International Nuclear Information System (INIS)

Feng, Tianyu; Xu, Youlong; Zhang, Zhengwei; Mao, Shengchun

2015-01-01

Graphical abstract: - Highlights: • How Ag transfers F − to the adjacent Si atom was investigated and deduced by DFT at atomic scale. • Three-electrode CV tests proved the transferring function of Ag in the etching reaction. • Uniform SiNWAs were fabricated on unpolished silicon wafers with KOH pretreatment. - Abstract: Uniform silicon nanowires arrays (SiNWAs) were fabricated on unpolished rough silicon wafers through KOH pretreatment followed by silver-assisted chemical etching (SACE). Density functional theory (DFT) calculations were used to investigate the function of silver (Ag) at atomic scale in the etching process. Among three adsorption sites of Ag atom on Si(1 0 0) surface, Ag(T4) above the fourth-layer surface Si atoms could transfer fluorinion (F − ) to adjacent Si successfully due to its stronger electrostatic attraction force between Ag(T4) and F − , smaller azimuth angle of F−Ag(T4)−Si, shorter bond length of F−Si compared with F−Ag. As F − was transferred to adjacent Si by Ag(T4) one by one, the Si got away from the wafer in the form of SiF 4 when it bonded with enough F − while Ag(T4) was still attached onto the Si wafer ready for next transfer. Cyclic voltammetry tests confirmed that Ag can improve the etching rate by transferring F − to Si

A comparative study of in-flow and micro-patterning biofunctionalization protocols for nanophotonic silicon-based biosensors.

Science.gov (United States)

González-Guerrero, Ana Belén; Alvarez, Mar; García Castaño, Andrés; Domínguez, Carlos; Lechuga, Laura M

2013-03-01

Reliable immobilization of bioreceptors over any sensor surface is the most crucial step for achieving high performance, selective and sensitive biosensor devices able to analyze human samples without the need of previous processing. With this aim, we have implemented an optimized scheme to covalently biofunctionalize the sensor area of a novel nanophotonic interferometric biosensor. The proposed method is based on the ex-situ silanization of the silicon nitride transducer surface by the use of a carboxyl water soluble silane, the carboxyethylsilanetriol sodium salt (CTES). The use of an organosilane stable in water entails advantages in comparison with usual trialkoxysilanes such as avoiding the generation of organic waste and leading to the assembly of compact monolayers due to the high dielectric constant of water. Additionally, cross-linking is prevented when the conditions (e.g. immersion time, concentration of silane) are optimized. This covalent strategy is followed by the bioreceptor linkage on the sensor area surface using two different approaches: an in-flow patterning and a microcontact printing using a biodeposition system. The performance of the different bioreceptor layers assembled is compared by the real-time and label-free immunosensing of the proteins BSA/mAb BSA, employed as a model molecular pair. Although the results demonstrated that both strategies provide the biosensor with a stable biological interface, the performance of the bioreceptor layer assembled by microcontact printing slightly improves the biosensing capabilities of the photonic biosensor. Copyright © 2012 Elsevier Inc. All rights reserved.

Recovery of hexagonal Si-IV nanowires from extreme GPa pressure

Energy Technology Data Exchange (ETDEWEB)

Smith, Bennett E. [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Zhou, Xuezhe; Roder, Paden B. [Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195 (United States); Abramson, Evan H. [Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195 (United States); Pauzauskie, Peter J., E-mail: peterpz@uw.edu [Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195 (United States); Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2016-05-14

We use Raman spectroscopy in tandem with transmission electron microscopy and density functional theory simulations to show that extreme (GPa) pressure converts the phase of silicon nanowires from cubic (Si-I) to hexagonal (Si-IV) while preserving the nanowire's cylindrical morphology. In situ Raman scattering of the longitudinal transverse optical (LTO) mode demonstrates the high-pressure Si-I to Si-II phase transition near 9 GPa. Raman signal of the LTO phonon shows a decrease in intensity in the range of 9–14 GPa. Then, at 17 GPa, it is no longer detectable, indicating a second phase change (Si-II to Si-V) in the 14–17 GPa range. Recovery of exotic phases in individual silicon nanowires from diamond anvil cell experiments reaching 17 GPa is also shown. Raman measurements indicate Si-IV as the dominant phase in pressurized nanowires after decompression. Transmission electron microscopy and electron diffraction confirm crystalline Si-IV domains in individual nanowires. Computational electromagnetic simulations suggest that heating from the Raman laser probe is negligible and that near-hydrostatic pressure is the primary driving force for the formation of hexagonal silicon nanowires.

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

International Nuclear Information System (INIS)

Saxena, Shailendra K.; Rai, Hari. M.; Late, Ravikiran; Sagdeo, Pankaj R.; Kumar, Rajesh

2015-01-01

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

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

KAUST Repository

Yao, Yan; Liu, Nian; McDowell, Matthew T.; Pasta, Mauro; Cui, Yi

2012-01-01

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

Intermediate Bandgap Solar Cells From Nanostructured Silicon

Energy Technology Data Exchange (ETDEWEB)

Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

2014-10-30

This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

Control growth of silicon nanocolumns' epitaxy on silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2013-04-15

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

Development of L-lactate dehydrogenase biosensor based on porous silicon resonant microcavities as fluorescence enhancers.

Science.gov (United States)

Jenie, S N Aisyiyah; Prieto-Simon, Beatriz; Voelcker, Nicolas H

2015-12-15

The up-regulation of L-lactate dehydrogenase (LDH), an intracellular enzyme present in most of all body tissues, is indicative of several pathological conditions and cellular death. Herein, we demonstrate LDH detection using porous silicon (pSi) microcavities as a luminescence-enhancing optical biosensing platform. Non-fluorescent resazurin was covalently attached onto the pSi surface via thermal hydrocarbonisation, thermal hydrosylilation and acylation. Each surface modification step was confirmed by means of FTIR and the optical shifts of the resonance wavelength of the microcavity. Thermal hydrocarbonisation also afforded excellent surface stability, ensuring that the resazurin was not reduced on the pSi surface. Using a pSi microcavity biosensor, the fluorescence signal upon detection of LDH was amplified by 10 and 5-fold compared to that of a single layer and a detuned microcavity, respectively, giving a limit of detection of 0.08 U/ml. The biosensor showed a linear response between 0.16 and 6.5 U/ml, covering the concentration range of LDH in normal as well as damaged tissues. The biosensor was selective for LDH and did not produce a signal upon incubation with another NAD-dependant enzyme L-glutamic dehydrogenase. The use of the pSi microcavity as a sensing platform reduced reagent usage by 30% and analysis time threefold compared to the standard LDH assay in solution. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication and characterization of a chemically oxidized-nanostructured porous silicon based biosensor implementing orienting protein A.

Science.gov (United States)

Naveas, Nelson; Hernandez-Montelongo, Jacobo; Pulido, Ruth; Torres-Costa, Vicente; Villanueva-Guerrero, Raúl; Predestinación García Ruiz, Josefa; Manso-Silván, Miguel

2014-03-01

Nanostructured porous silicon (PSi) elicits as a very attractive material for future biosensing systems due to its high surface area, biocompatibility and well-established fabrication methods. In order to engineer its performance as a biosensor transducer platform, the density of immunoglobulins properly immobilized and oriented onto the surface needs to be optimized. In this work we fabricated and characterized a novel biosensing system focusing on the improvement of the biofunctionalization cascade. The system consists on a chemically oxidized PSi platform derivatized with 3-aminopropyltriethoxysilane (APTS) that is coupled to Staphylococcus protein A (SpA). The chemical oxidation has previously demonstrated to enhance the biofunctionalization process and here "by implementing SpA" a molecularly oriented immunosensor is achieved. The biosensor system is characterized in terms of its chemical composition, wettability and optical reflectance. Finally, this system is successfully exploited to develop a biosensor for detecting asymmetric dimethylarginine (ADMA), an endogenous molecule involved in cardiovascular diseases. Therefore, this work is relevant from the point of view of design and optimization of the biomolecular immobilization cascade on PSi surfaces with the added value of contribution to the development of new assays for detecting ADMA with a view on prevention of cardiovascular diseases. Copyright © 2013 Elsevier B.V. All rights reserved.

VLS-grown diffusion doped ZnO nanowires and their luminescence properties

International Nuclear Information System (INIS)

Roy, Pushan Guha; Dutta, Amartya; Das, Arpita; Bhattacharyya, Anirban; Sen, Sayantani; Pramanik, Pallabi

2015-01-01

Zinc Oxide (ZnO) nanowires were deposited by vapor–liquid–solid (VLS) method on to aluminum doped ZnO (AZO) thin films grown by sol-gel technique. For various device applications, current injection into such nanowires is critical. This is expected to be more efficient for ZnO nanowires deposited on to AZO compared to those deposited on to a foreign substrate such as silicon. In this work we compare the morphological and optical properties of nanowires grown on AZO with those grown under similar conditions on silicon (Si) wafers. For nanowires grown on silicon, diameters around 44 nm with heights around 2.2 μm were obtained. For the growth on to AZO, the diameters were around 90 nm while the heights were around 520 nm. Room temperature photoluminescence (RT-PL) measurements show improved near band-edge emission for nanowires grown on to AZO, indicating higher material quality. This is further established by low temperature photoluminescence (LT-PL) measurements where excitonic transitions with width as small as 14 meV have been obtained at 4 K for such structures. Electron energy loss spectroscopy (EELS) studies indicate the presence of Al in the nanowires, indicating a new technique for introduction of dopants into these structures. These results indicate that ZnO nanowires on sol-gel grown AZO thin films show promise in the development of various optoelectronic devices. (paper)

Mechanics of nanowire/nanotube in-surface buckling on elastomeric substrates

Energy Technology Data Exchange (ETDEWEB)

Xiao, J; Huang, Y [Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208 (United States); Ryu, S Y; Paik, U [Division of Materials Science and Engineering, Hanyang University, 17 Hangdang-dong, Sungdong-gu, Seoul 133-791 (Korea, Republic of); Hwang, K-C [Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Rogers, J A, E-mail: y-huang@northwestern.edu, E-mail: jrogers@uiuc.edu [Department of Materials Science and Engineering, Frederick-Seitz Materials Research Laboratory and Beckman Institute, University of Illinois at Urbana-Champaign, Illinois 61801 (United States)

2010-02-26

A continuum mechanics theory is established for the in-surface buckling of one-dimensional nanomaterials on compliant substrates, such as silicon nanowires on elastomeric substrates observed in experiments. Simple analytical expressions are obtained for the buckling wavelength, amplitude and critical buckling strain in terms of the bending and tension stiffness of the nanomaterial and the substrate elastic properties. The analysis is applied to silicon nanowires, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanotube bundles. For silicon nanowires, the measured buckling wavelength gives Young's modulus to be 140 GPa, which agrees well with the prior experimental studies. It is shown that the energy for in-surface buckling is lower than that for normal (out-of-surface) buckling, and is therefore energetically favorable.

Mechanics of nanowire/nanotube in-surface buckling on elastomeric substrates

International Nuclear Information System (INIS)

Xiao, J; Huang, Y; Ryu, S Y; Paik, U; Hwang, K-C; Rogers, J A

2010-01-01

A continuum mechanics theory is established for the in-surface buckling of one-dimensional nanomaterials on compliant substrates, such as silicon nanowires on elastomeric substrates observed in experiments. Simple analytical expressions are obtained for the buckling wavelength, amplitude and critical buckling strain in terms of the bending and tension stiffness of the nanomaterial and the substrate elastic properties. The analysis is applied to silicon nanowires, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanotube bundles. For silicon nanowires, the measured buckling wavelength gives Young's modulus to be 140 GPa, which agrees well with the prior experimental studies. It is shown that the energy for in-surface buckling is lower than that for normal (out-of-surface) buckling, and is therefore energetically favorable.

Optical analysis of a III-V-nanowire-array-on-Si dual junction solar cell.

Science.gov (United States)

Chen, Yang; Höhn, Oliver; Tucher, Nico; Pistol, Mats-Erik; Anttu, Nicklas

2017-08-07

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. First, we consider a simplified system of bare, uncoated III-V nanowires on the silicon substrate and optimize the absorption in the nanowires. We find that an optimum absorption in 2000 nm long nanowires is reached for a dense array of approximately 15 nanowires per square micrometer. However, when we coat such an array with a conformal indium tin oxide (ITO) top contact layer, a substantial absorption loss occurs in the ITO. This ITO could absorb 37% of the low energy photons intended for the silicon subcell. By moving to a design with a 50 nm thick, planarized ITO top layer, we can reduce this ITO absorption to 5%. However, such a planarized design introduces additional reflection losses. We show that these reflection losses can be reduced with a 100 nm thick SiO 2 anti-reflection coating on top of the ITO layer. When we at the same time include a Si 3 N 4 layer with a thickness of 90 nm on the silicon surface between the nanowires, we can reduce the average reflection loss of the silicon cell from 17% to 4%. Finally, we show that different approximate models for the absorption in the silicon substrate can lead to a 15% variation in the estimated photocurrent density in the silicon subcell.

Controlled growth of single nanowires within a supported alumina template

DEFF Research Database (Denmark)

Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.

2006-01-01

A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire...

Tailoring Thermal Radiative Properties with Doped-Silicon Nanowires

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhuomin [Georgia Inst. of Technology, Atlanta, GA (United States)

2017-08-28

Aligned doped-silicon nanowire (D-SiNW) arrays form a hyperbolic metamaterial in the mid-infrared and have unique thermal radiative properties, such as broadband omnidirectional absorption, low-loss negative refraction, etc. A combined theoretical and experimental investigation will be performed to characterize D-SiNW arrays and other metamaterials for tailoring thermal radiative properties. Near-field thermal radiation between anisotropic materials with hyperbolic dispersions will also be predicted for potential application in energy harvesting. A new kind of anisotropic metamaterial with a hyperbolic dispersion in a broad infrared region has been proposed and demonstrated based on aligned doped-silicon nanowire (D-SiNW) arrays. D-SiNW-based metamaterials have unique thermal radiative properties, such as broadband omnidirectional absorption whose width and location can be tuned by varying the filling ratio and/or doping level. Furthermore, high figure of merit (FOM) can be achieved in a wide spectral region, suggesting that D-SiNW arrays may be used as a negative refraction material with much less loss than other structured materials, such as layered semiconductor materials. We have also shown that D-SiNWs and other nanostructures can significantly enhance near-field thermal radiation. The study of near-field radiative heat transfer between closely spaced objects and the electromagnetic wave interactions with micro/nanostructured materials has become an emerging multidisciplinary field due to its importance in advanced energy systems, manufacturing, local thermal management, and high spatial resolution thermal sensing and mapping. We have performed extensive study on the energy streamlines involving anisotropic metamaterials and the applicability of the effective medium theory for near-field thermal radiation. Graphene as a 2D material has attracted great attention in nanoelectronics, plasmonics, and energy harvesting. We have shown that graphene can be used to

Biodegradable elastomers and silicon nanomembranes/nanoribbons for stretchable, transient electronics, and biosensors.

Science.gov (United States)

Hwang, Suk-Won; Lee, Chi Hwan; Cheng, Huanyu; Jeong, Jae-Woong; Kang, Seung-Kyun; Kim, Jae-Hwan; Shin, Jiho; Yang, Jian; Liu, Zhuangjian; Ameer, Guillermo A; Huang, Yonggang; Rogers, John A

2015-05-13

Transient electronics represents an emerging class of technology that exploits materials and/or device constructs that are capable of physically disappearing or disintegrating in a controlled manner at programmed rates or times. Inorganic semiconductor nanomaterials such as silicon nanomembranes/nanoribbons provide attractive choices for active elements in transistors, diodes and other essential components of overall systems that dissolve completely by hydrolysis in biofluids or groundwater. We describe here materials, mechanics, and design layouts to achieve this type of technology in stretchable configurations with biodegradable elastomers for substrate/encapsulation layers. Experimental and theoretical results illuminate the mechanical properties under large strain deformation. Circuit characterization of complementary metal-oxide-semiconductor inverters and individual transistors under various levels of applied loads validates the design strategies. Examples of biosensors demonstrate possibilities for stretchable, transient devices in biomedical applications.

An analytic model for gate-all-around silicon nanowire tunneling field effect transistors

International Nuclear Information System (INIS)

Liu Ying; He Jin; Chan Mansun; Ye Yun; Zhao Wei; Wu Wen; Deng Wan-Ling; Wang Wen-Ping; Du Cai-Xia

2014-01-01

An analytical model of gate-all-around (GAA) silicon nanowire tunneling field effect transistors (NW-TFETs) is developted based on the surface potential solutions in the channel direction and considering the band to band tunneling (BTBT) efficiency. The three-dimensional Poisson equation is solved to obtain the surface potential distributions in the partition regions along the channel direction for the NW-TFET, and a tunneling current model using Kane's expression is developed. The validity of the developed model is shown by the good agreement between the model predictions and the TCAD simulation results. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

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

Directory of Open Access Journals (Sweden)

Xiang Zhang

2016-08-01

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

Si nanowires/Cu nanowires bilayer fabric as a lithium ion capacitor anode with excellent performance

Science.gov (United States)

Lai, Chien-Ming; Kao, Tzu-Lun; Tuan, Hsing-Yu

2018-03-01

A light and binder-free bilayer fabric electrode composed of silicon nanowires and copper nanowires for lithium-ion capacitors (LICs) is reported. A lithium ion capacitor is proposed employing pre-lithiated silicon/copper nanowire fabric and activated carbon as the anode and the cathode, respectively. These LICs show remarkable performance with a specific capacitance of 156 F g-1 at 0.1 A g-1, which is approximately twice of that of activated carbon in electric double-layer capacitors (EDLCs), and still exhibit a fine specific capacitance of 68 F g-1 even at a high current density of 20 A g-1. At a low power density of 193 W kg-1, the Si/Cu fabric//AC LIC can achieve high energy density of 210 W h kg-1. As the power density is increased to 99 kW kg-1, the energy density still remains at 43 W h kg-1, showing the prominent rate performance.

Functionalized polypyrrole nanotube arrays as electrochemical biosensor for the determination of copper ions

International Nuclear Information System (INIS)

Lin Meng; Hu Xiaoke; Ma Zhaohu; Chen Lingxin

2012-01-01

Highlights: ► PPy nanotube arrays were electropolymerized using ZnO nanowire arrays as templates. ► PPy nanotube arrays were anchored onto ITO glass without any chemical linker. ► Using SWV, the biosensor was found to be highly sensitive and selective to Cu 2+ . ► The biosensor was successfully applied for the determination of Cu 2+ in drinking water. - Abstract: A novel electrochemical biosensor based on functionalized polypyrrole (PPy) nanotube arrays modified with a tripeptide (Gly-Gly-His) proved to be highly effective for electrochemical analysis of copper ions (Cu 2+ ). The vertically oriented PPy nanotube arrays were electropolymerized by using modified zinc oxide (ZnO) nanowire arrays as templates which were electrodeposited on indium–tin oxide (ITO) coated glass substrates. The electrodes were functionalized by appending pyrrole-α-carboxylic acid onto the surface of polypyrrole nanotube arrays by electrochemical polymerization. The carboxylic groups of the polymer were covalently coupled with the amine groups of the tripeptide, and its structural features were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy. The tripeptide modified PPy nanotube arrays electrode was used for the electrochemical analysis of various trace copper ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu 2+ in the range of 0.1–30 μM. Furthermore, the developed biosensor exhibited a high stability and reproducibility, despite the repeated use of the biosensor electrode.

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

KAUST Repository

Li, Zhou

2009-10-14

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

Patterned growth of carbon nanotubes over vertically aligned silicon nanowire bundles for achieving uniform field emission.

Science.gov (United States)

Hung, Yung-Jr; Huang, Yung-Jui; Chang, Hsuan-Chen; Lee, Kuei-Yi; Lee, San-Liang

2014-01-01

A fabrication strategy is proposed to enable precise coverage of as-grown carbon nanotube (CNT) mats atop vertically aligned silicon nanowire (VA-SiNW) bundles in order to realize a uniform bundle array of CNT-SiNW heterojunctions over a large sample area. No obvious electrical degradation of as-fabricated SiNWs is observed according to the measured current-voltage characteristic of a two-terminal single-nanowire device. Bundle arrangement of CNT-SiNW heterojunctions is optimized to relax the electrostatic screening effect and to maximize the field enhancement factor. As a result, superior field emission performance and relatively stable emission current over 12 h is obtained. A bright and uniform fluorescent radiation is observed from CNT-SiNW-based field emitters regardless of its bundle periodicity, verifying the existence of high-density and efficient field emitters on the proposed CNT-SiNW bundle arrays.

High-quality GaN nanowires grown on Si and porous silicon by thermal evaporation

Energy Technology Data Exchange (ETDEWEB)

Shekari, L., E-mail: lsg09_phy089@student.usm.my [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Ramizy, A.; Omar, K.; Hassan, H. Abu; Hassan, Z. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia)

2012-12-15

Highlights: Black-Right-Pointing-Pointer A new kind of substrate (porous silicon) was used. Black-Right-Pointing-Pointer Also this research introduces an easy and safe method to grow high quality GaN NWs. Black-Right-Pointing-Pointer This is a new growth process to decrease the cost, complexity of growth of GaN NWs. Black-Right-Pointing-Pointer It is a controllable method to synthesize GaN NWs by thermal evaporation. - Abstract: Nanowires (NWs) of GaN thin films were prepared on as-grown Si (1 1 1) and porous silicon (PS) substrates using thermal evaporation method. The film growth produced high-quality wurtzite GaN NWs. The size, morphology, and nanostructures of the crystals were investigated through scanning electron microscopy, high-resolution X-ray diffraction and photoluminescence spectroscopy. The NWs grown on porous silicon were thinner, longer and denser compared with those on as-grown Si. The energy band gap of the NWs grown on PS was larger than that of NWs on as-grown Si. This is due to the greater quantum confinement effects of the crystalline structure of the NWs grown on PS.

Label-free SnO2 nanowire FET biosensor for protein detection

Science.gov (United States)

Jakob, Markus H.; Dong, Bo; Gutsch, Sebastian; Chatelle, Claire; Krishnaraja, Abinaya; Weber, Wilfried; Zacharias, Margit

2017-06-01

Novel tin oxide field-effect-transistors (SnO2 NW-FET) for pH and protein detection applicable in the healthcare sector are reported. With a SnO2 NW-FET the proof-of-concept of a bio-sensing device is demonstrated using the carrier transport control of the FET channel by a (bio-) liquid modulated gate. Ultra-thin Al2O3 fabricated by a low temperature atomic layer deposition (ALD) process represents a sensitive layer to H+ ions safeguarding the nanowire at the same time. Successful pH sensitivity is demonstrated for pH ranging from 3 to 10. For protein detection, the SnO2 NW-FET is functionalized with a receptor molecule which specifically interacts with the protein of interest to be detected. The feasibility of this approach is demonstrated via the detection of a biotinylated protein using a NW-FET functionalized with streptavidin. An immediate label-free electronic read-out of the signal is shown. The well-established Enzyme-Linked Immunosorbent Assay (ELISA) method is used to determine the optimal experimental procedure which would enable molecular binding events to occur while being compatible with a final label-free electronic read-out on a NW-FET. Integration of the bottom-up fabricated SnO2 NW-FET pH- and biosensor into a microfluidic system (lab-on-a-chip) allows the automated analysis of small volumes in the 400 μl range as would be desired in portable on-site point-of-care (POC) devices for medical diagnosis.

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

International Nuclear Information System (INIS)

Moselund, K E; Ghoneim, H; Schmid, H; Bjoerk, M T; Loertscher, E; Karg, S; Signorello, G; Webb, D; Tschudy, M; Beyeler, R; Riel, H

2010-01-01

In this work we investigate doping by solid-state diffusion from a doped oxide layer, obtained by plasma-enhanced chemical vapor deposition (PECVD), as a means for selectively doping silicon nanowires (NWs). We demonstrate both n-type (phosphorous) and p-type (boron) doping up to concentrations of 10 20 cm -3 , and find that this doping mechanism is more efficient for NWs as opposed to planar substrates. We observe no diameter dependence in the range of 25 to 80 nm, which signifies that the NWs are uniformly doped. The drive-in temperature (800-950 deg. C) can be used to adjust the actual doping concentration in the range 2 x 10 18 to 10 20 cm -3 . Furthermore, we have fabricated NMOS and PMOS devices to show the versatility of this approach and the possibility of achieving segmented doping of NWs. The devices show high I on /I off ratios of around 10 7 and, especially for the PMOS, good saturation behavior and low hysteresis.

Functionalization of silicon nanowires by conductive and non-conductive polymers

Science.gov (United States)

Belhousse, S.; Tighilt, F.-Z.; Sam, S.; Lasmi, K.; Hamdani, K.; Tahanout, L.; Megherbi, F.; Gabouze, N.

2017-11-01

The work reports on the development of hybrid devices based on silicon nanowires (SiNW) with polymers and the difference obtained when using conductive and non-conductive polymers. SiNW have attracted much attention due to their importance in understanding the fundamental properties at low dimensionality as well as their potential application in nanoscale devices as in field effect transistors, chemical or biological sensors, battery electrodes and photovoltaics. SiNW arrays were formed using metal assisted chemical etching method. This process is simple, fast and allows obtaining a wide range of silicon nanostructures. Hydrogen-passivated SiNW surfaces show relatively poor stability. Surface modification with organic species confers the desired stability and enhances the surface properties. For this reason, this work proposes a covalent grafting of organic material onto SiNW surface. We have chosen a non-conductive polymer polyvinylpyrrolidone (PVP) and conductive polymers polythiophene (PTh) and polypyrrole (PPy), in order to evaluate the electric effect of the polymers on the obtained materials. The hybrid structures were elaborated by the polymerization of the corresponding conjugated monomers by electrochemical route; this electropolymerization offers several advantages such as simplicity and rapidity. SiNW functionalization by conductive polymers has shown to have a huge effect on the electrical mobility. Hybrid surface morphologies were characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR-ATR) and contact angle measurements.

Nanogap biosensors for electrical and label-free detection of biomolecular interactions

International Nuclear Information System (INIS)

Kyu Kim, Sang; Cho, Hyunmin; Park, Hye-Jung; Kwon, Dohyoung; Min Lee, Jeong; Hyun Chung, Bong

2009-01-01

We demonstrate nanogap biosensors for electrical and label-free detection of biomolecular interactions. Parallel fabrication of nanometer distance gaps has been achieved using a silicon anisotropic wet etching technique on a silicon-on-insulator (SOI) wafer with a finely controllable silicon device layer. Since silicon anisotropic wet etching resulted in a trapezoid-shaped structure whose end became narrower during the etching, the nanogap structure was simply fabricated on the device layer of a SOI wafer. The nanogap devices were individually addressable and a gap size of less than 60 nm was obtained. We demonstrate that the nanogap biosensors can electrically detect biomolecular interactions such as biotin/streptavidin and antigen/antibody pairs. The nanogap devices show a current increase when the proteins are bound to the surface. The current increases proportionally depending upon the concentrations of the molecules in the range of 100 fg ml -1 -100 ng ml -1 at 1 V bias. It is expected that the nanogap developed here could be a highly sensitive biosensor platform for label-free detection of biomolecular interactions.

Enhanced ionized impurity scattering in nanowires

Science.gov (United States)

Oh, Jung Hyun; Lee, Seok-Hee; Shin, Mincheol

2013-06-01

The electronic resistivity in silicon nanowires is investigated by taking into account scattering as well as the donor deactivation from the dielectric mismatch. The effects of poorly screened dopant atoms from the dielectric mismatch and variable carrier density in nanowires are found to play a crucial role in determining the nanowire resistivity. Using Green's function method within the self-consistent Born approximation, it is shown that donor deactivation and ionized impurity scattering combined with the charged interface traps successfully to explain the increase in the resistivity of Si nanowires while reducing the radius, measured by Björk et al. [Nature Nanotech. 4, 103 (2009)].

Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Maruthupandy, Muthusamy; Anand, Muthusamy; Beevi, Akbar Sait Hameedha; Priya, Radhakrishnan Jeeva; Maduraiveeran, Govindhan

2015-01-01

The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices. (paper)

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-09-14

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

Static friction between silicon nanowires and elastomeric substrates.

Science.gov (United States)

Qin, Qingquan; Zhu, Yong

2011-09-27

This paper reports the first direct measurements of static friction force and interfacial shear strength between silicon (Si) nanowires (NWs) and poly(dimethylsiloxane) (PDMS). A micromanipulator is used to manipulate and deform the NWs under a high-magnification optical microscope in real time. The static friction force is measured based on "the most-bent state" of the NWs. The static friction and interface shear strength are found to depend on the ultraviolet/ozone (UVO) treatment of PDMS. The shear strength starts at 0.30 MPa without UVO treatment, increases rapidly up to 10.57 MPa at 60 min of treatment and decreases for longer treatment. Water contact angle measurements suggest that the UVO-induced hydrophobic-to-hydrophilic conversion of PDMS surface is responsible for the increase in the static friction, while the hydrophobic recovery effect contributes to the decrease. The static friction between NWs and PDMS is of critical relevance to many device applications of NWs including NW-based flexible/stretchable electronics, NW assembly and nanocomposites (e.g., supercapacitors). Our results will enable quantitative interface design and control for such applications. © 2011 American Chemical Society

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

International Nuclear Information System (INIS)

Chen Yong; Luo Guanghong; Diao Jiajie; Chornoguz, Olesya; Reeves, Mark; Vertes, Akos

2007-01-01

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

Growth and applicability of radiation-responsive silica nanowires

Science.gov (United States)

Bettge, Martin

Surface energetics play an important role in processes on the nanoscale. Nanowire growth via vapor-liquid-solid (VLS) mechanism is no exception in this regard. Interfacial and line energies are found to impose some fundamental limits during three-phase nanowire growth and lead to formation of stranded nanowires with fascinating characteristics such as high responsiveness towards ion irradiation. By using two materials with a relatively low surface energy (indium and silicon oxide) this is experimentally and theoretically demonstrated in this doctoral thesis. The augmentation of VLS nanowire growth with ion bombardment enables fabrication of vertically aligned silica nanowires over large areas. Synthesis of their arrays begins with a thin indium film deposited on a Si or SiO 2 surface. At temperatures below 200ºC, the indium film becomes a self-organized seed layer of molten droplets, receiving a flux of atomic silicon by DC magnetron sputtering. Simultaneous vigorous ion bombardment through substrate biasing aligns the growing nanowires vertically and expedites mixing of oxygen and silicon into the indium. The vertical growth rate can reach up to 1000 nm-min-1 in an environment containing only argon and traces of water vapor. Silicon oxide precipitates from each indium seed in the form of multiple thin strands having diameters less than 9 nm and practically independent of droplet size. The strands form a single loose bundle, eventually consolidating to form one vertically aligned nanowire. These observations are in stark contrast to conventional VLS growth in which one liquid droplet precipitates a single solid nanowire and in which the precipitated wire diameter is directly proportional to the droplet diameter. The origin of these differences is revealed through a detailed force balance analysis, analogous to Young's relation, at the three-phase line. The liquid-solid interfacial energy of indium/silica is found to be the largest energy contribution at the three

In situ-growth of silica nanowires in ceramic carbon composites

Directory of Open Access Journals (Sweden)

Rahul Kumar

2017-09-01

Full Text Available An understanding of the processing and microstructure of ceramic–carbon composites is critical to development of these composites for applications needing electrically conducting, thermal shock resistant ceramic materials. In the present study green compacts of carbon ceramic composites were prepared either by slurry processing or dry powder blending of one or more of the three — clay, glass, alumina and carbon black or graphite. The dried green compacts were sintered at 1400 °C in flowing argon. The ceramic carbon composites except the ones without clay addition showed formation of silica nanowires. The silica nanowire formation was observed in both samples prepared by slip casting and dry powder compaction containing either carbon black or graphite. TEM micrographs showed presence of carbon at the core of the silica nanowires indicating that carbon served the role of a catalyst. Selected area electron diffraction (SAED suggested that the silica nanowires are amorphous. Prior studies have reported formation of silica nanowires from silicon, silica, silicon carbide but this is the first report ever on formation of silica nanowires from clay.

Thermally responsive silicon nanowire arrays for native/denatured-protein separation

International Nuclear Information System (INIS)

Wang Hongwei; Wang Yanwei; Yuan Lin; Wang Lei; Yang Weikang; Wu Zhaoqiang; Li Dan; Chen Hong

2013-01-01

We present our findings of the selective adsorption of native and denatured proteins onto thermally responsive, native-protein resistant poly(N-isopropylacrylamide) (PNIPAAm) decorated silicon nanowire arrays (SiNWAs). The PNIPAAm–SiNWAs surface, which shows very low levels of native-protein adsorption, favors the adsorption of denatured proteins. The amount of denatured-protein adsorption is higher at temperatures above the lower critical solution temperature (LCST) of PNIPAAm. Temperature cycling surrounding the LCST, which ensures against thermal denaturation of native proteins, further increases the amount of denatured-protein adsorption. Moreover, the PNIPAAm–SiNWAs surface is able to selectively adsorb denatured protein even from mixtures of different protein species; meanwhile, the amount of native proteins in solution is kept nearly at its original level. It is believed that these results will not only enrich current understanding of protein interactions with PNIPAAm-modified SiNWAs surfaces, but may also stimulate applications of PNIPAAm–SiNWAs surfaces for native/denatured protein separation. (paper)

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...

Stepped piezoresistive microcantilever designs for biosensors

International Nuclear Information System (INIS)

Ansari, Mohd Zahid; Cho, Chongdu; Urban, Gerald

2012-01-01

The sensitivity of a piezoresistive microcantilever biosensor strongly depends on its ability to convert the surface stress-induced deflections into large resistance change. To improve the sensitivity, we present stepped microcantilever biosensor designs that show significant resistance change compared with commonly used rectangular designs. The cantilever is made of silicon dioxide with a u-shaped silicon piezoresistor. The surface stress-induced deflections, bimorph deflection, fundamental resonant frequency and self-heating properties of the cantilever are studied using the FEM software. The surface stress-induced deflections are compared against the analytical model derived in this work. Results show that stepped designs have better signal-to-noise ratio than the rectangular ones and cantilevers with l/L between 0.5 and 0.75 are better designs for improving sensitivity. (paper)

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)

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.

Stretchable Conductive Composites from Cu-Ag Nanowire Felt.

Science.gov (United States)

Catenacci, Matthew J; Reyes, Christopher; Cruz, Mutya A; Wiley, Benjamin J

2018-04-24

Materials that retain a high conductivity under strain are essential for wearable electronics. This article describes a conductive, stretchable composite consisting of a Cu-Ag core-shell nanowire felt infiltrated with a silicone elastomer. This composite exhibits a retention of conductivity under strain that is superior to any composite with a conductivity greater than 1000 S cm -1 . This work also shows how the mechanical properties, conductivity, and deformation mechanism of the composite changes as a function of the stiffness of the silicone matrix. The retention of conductivity under strain was found to decrease as the Young's modulus of the matrix increased. This was attributed to void formation as a result of debonding between the nanowire felt and the elastomer. The nanowire composite was also patterned to create serpentine circuits with a stretchability of 300%.

Self-assisted GaAs nanowires with selectable number density on Silicon without oxide layer

International Nuclear Information System (INIS)

Bietti, S; Somaschini, C; Esposito, L; Sanguinetti, S; Frigeri, C; Fedorov, A; Geelhaar, L

2014-01-01

We present the growth of self-assisted GaAs nanowires (NWs) with selectable number density on bare Si(1 1 1), not covered by the silicon oxide. We determine the number density of the NWs by initially self-assembling GaAs islands on whose top a single NW is nucleated. The number density of the initial GaAs base islands can be tuned by droplet epitaxy and the same degree of control is then transferred to the NWs. This procedure is completely performed during a single growth in an ultra-high vacuum environment and requires neither an oxide layer covering the substrate, nor any pre-patterning technique. (paper)

An in-plane solid-liquid-solid growth mode for self-avoiding lateral silicon nanowires.

Science.gov (United States)

Yu, Linwei; Alet, Pierre-Jean; Picardi, Gennaro; Roca i Cabarrocas, Pere

2009-03-27

We report an in-plane solid-liquid-solid (IPSLS) mode for obtaining self-avoiding lateral silicon nanowires (SiNW) in a reacting-gas-free annealing process, where the growth of SiNWs is guided by liquid indium drops that transform the surrounding a-SiratioH matrix into crystalline SiNWs. The SiNWs can be approximately mm long, with the smallest diameter down to approximately 22 nm. A high growth rate of >10(2) nm/s and rich evolution dynamics are revealed in a real-time in situ scanning electron microscopy observation. A qualitative growth model is proposed to account for the major features of this IPSLS SiNW growth mode.

Molecular dynamics study of the thermal expansion coefficient of silicon

Energy Technology Data Exchange (ETDEWEB)

Nejat Pishkenari, Hossein, E-mail: nejat@sharif.edu; Mohagheghian, Erfan; Rasouli, Ali

2016-12-16

Due to the growing applications of silicon in nano-scale systems, a molecular dynamics approach is employed to investigate thermal properties of silicon. Since simulation results rely upon interatomic potentials, thermal expansion coefficient (TEC) and lattice constant of bulk silicon have been obtained using different potentials (SW, Tersoff, MEAM, and EDIP) and results indicate that SW has a better agreement with the experimental observations. To investigate effect of size on TEC of silicon nanowires, further simulations are performed using SW potential. To this end, silicon nanowires of different sizes are examined and their TEC is calculated by averaging in different directions ([100], [110], [111], and [112]) and various temperatures. Results show that as the size increases, due to the decrease of the surface effects, TEC approaches its bulk value. - Highlights: • MD simulations of TEC and lattice constant of bulk silicon. • Effects of four potentials on the results. • Comparison to experimental data. • Investigating size effect on TEC of silicon nanowires.

Real-time impedance analysis of silica nanowire toxicity on epithelial breast cancer cells.

Science.gov (United States)

Alexander, Frank A; Huey, Eric G; Price, Dorielle T; Bhansali, Shekhar

2012-12-21

Silica nanowires have great potential for usage in the development of highly sensitive in vivo biosensors used for biomarker monitoring. However, careful analysis of nanowire toxicity is required prior to placing these sensors within the human body. This paper describes a real-time and quantitative analysis of nanowire cytotoxicity using impedance spectroscopy; improving upon studies that have utilized traditional endpoint assays. Silica nanowires were grown using the vapor liquid solid (VLS) method, mixed with Dulbecco's Modified Eagle Medium (DMEM) and exposed to Hs578T epithelial breast cancer cells at concentrations of 0 μg ml(-1), 1 μg ml(-1), 50 μg ml(-1) and 100 μg ml(-1). Real-time cellular responses to silica nanowires confirm that while not cytotoxic, silica nanowires at high concentrations (≥50 μg ml(-1)) are toxic to cells, and also suggest that cell death is due to mechanical disturbances of high numbers of nanowires.

Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

Science.gov (United States)

Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

2016-06-28

Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect.

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

International Nuclear Information System (INIS)

Dalchiele, E.A.; Martin, F.; Leinen, D.; Marotti, R.E.; Ramos-Barrado, J.R.

2010-01-01

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

Silicon nanowires enhanced proliferation and neuronal differentiation of neural stem cell with vertically surface microenvironment.

Science.gov (United States)

Yan, Qiuting; Fang, Lipao; Wei, Jiyu; Xiao, Guipeng; Lv, Meihong; Ma, Quanhong; Liu, Chunfeng; Wang, Wang

2017-09-01

Owing to its biocompatibility, noncytotoxicity, biodegradability and three-dimensional structure, vertically silicon nanowires (SiNWs) arrays are a promising scaffold material for tissue engineering, regenerative medicine and relevant medical applications. Recently, its osteogenic differentiation effects, reorganization of cytoskeleton and regulation of the fate on stem cells have been demonstrated. However, it still remains unknown whether SiNWs arrays could affect the proliferation and neuronal differentiation of neural stem cells (NSCs) or not. In the present study, we have employed vertically aligned SiNWs arrays as culture systems for NSCs and proved that the scaffold material could promote the proliferation and neuronal differentiation of NSCs while maintaining excellent cell viability and stemness. Immunofluorescence imaging analysis, Western blot and RT-PCR results reveal that NSCs proliferation and neuronal differentiation efficiency on SiNWs arrays are significant greater than that on silicon wafers. These results implicate SiNWs arrays could offer a powerful platform for NSCs research and NSCs-based therapy in the field of neural tissue engineering.

Optimization of pH sensing using silicon nanowire field effect transistors with HfO2 as the sensing surface

International Nuclear Information System (INIS)

Zafar, Sufi; D'Emic, Christopher; Afzali, Ali; Fletcher, Benjamin; Zhu, Y; Ning, Tak

2011-01-01

Silicon nanowire field effect transistor sensors with SiO 2 /HfO 2 as the gate dielectric sensing surface are fabricated using a top down approach. These sensors are optimized for pH sensing with two key characteristics. First, the pH sensitivity is shown to be independent of buffer concentration. Second, the observed pH sensitivity is enhanced and is equal to the Nernst maximum sensitivity limit of 59 mV/pH with a corresponding subthreshold drain current change of ∼ 650%/pH. These two enhanced pH sensing characteristics are attributed to the use of HfO 2 as the sensing surface and an optimized fabrication process compatible with silicon processing technology.

Optimization of pH sensing using silicon nanowire field effect transistors with HfO2 as the sensing surface.

Science.gov (United States)

Zafar, Sufi; D'Emic, Christopher; Afzali, Ali; Fletcher, Benjamin; Zhu, Y; Ning, Tak

2011-10-07

Silicon nanowire field effect transistor sensors with SiO(2)/HfO(2) as the gate dielectric sensing surface are fabricated using a top down approach. These sensors are optimized for pH sensing with two key characteristics. First, the pH sensitivity is shown to be independent of buffer concentration. Second, the observed pH sensitivity is enhanced and is equal to the Nernst maximum sensitivity limit of 59 mV/pH with a corresponding subthreshold drain current change of ∼ 650%/pH. These two enhanced pH sensing characteristics are attributed to the use of HfO(2) as the sensing surface and an optimized fabrication process compatible with silicon processing technology.

Biosensors based on cantilevers.

Science.gov (United States)

Alvarez, Mar; Carrascosa, Laura G; Zinoviev, Kiril; Plaza, Jose A; Lechuga, Laura M

2009-01-01

Microcantilevers based-biosensors are a new label-free technique that allows the direct detection of biomolecular interactions in a label-less way and with great accuracy by translating the biointeraction into a nanomechanical motion. Low cost and reliable standard silicon technologies are widely used for the fabrication of cantilevers with well-controlled mechanical properties. Over the last years, the number of applications of these sensors has shown a fast growth in diverse fields, such as genomic or proteomic, because of the biosensor flexibility, the low sample consumption, and the non-pretreated samples required. In this chapter, we report a dedicated design and a fabrication process of highly sensitive microcantilever silicon sensors. We will describe as well an application of the device in the environmental field showing the immunodetection of an organic toxic pesticide as an example. The cantilever biofunctionalization process and the subsequent pesticide determination are detected in real time by monitoring the nanometer-scale bending of the microcantilever due to a differential surface stress generated between both surfaces of the device.

ZrTiO4 nanowire growth using membrane-assisted Pechini route

Directory of Open Access Journals (Sweden)

P. R. de Lucena

2014-11-01

Full Text Available The high surface-to-volume ratio of nanowires makes them natural competitors as new device components. In this regard, a current major challenge is to produce quasi-one-dimensional nanostructures composed of well established oxide-based materials. This article reports the synthesis of ZrTiO4 nanowires on a silicon (100 wafer in a single-step deposition/thermal treatment. The template-directed membrane synthesis strategy was associated with the Pechini route and spin-coating deposition technique. ZrTiO4 nanowires were obtained at 700 ˚C with diameters in the range of 80-100 nm. FEG- SEM images were obtained to investigate ZrTiO4 nanowire formation on the silicon surface and energy dispersive x-ray detection (EDS and x-ray diffraction (XRD analyses were performed to confirm the oxide composition and structure.

ZrTiO4 Nanowire Growth Using Membrane-assisted Pechini Route

Directory of Open Access Journals (Sweden)

Poty Rodrigues de Lucena

2016-02-01

Full Text Available The high surface-to-volume ratio of nanowires makes them natural competitors as newer device components. In this regard, a current major challenge is to produce quasi-one-dimensional nanostructures composed of well-established oxide-based materials. This article reports the synthesis of ZrTiO4 nanowires on a silicon (100 wafer in a single-step deposition/thermal treatment. The template-directed membrane synthesis strategy was associated with the Pechini route and spin-coating deposition technique. ZrTiO4 nanowires were obtained at 700 °C with diameters in the range of 80-100 nm. FEGSEM images were obtained to investigate ZrTiO4 nanowire formation on the silicon surface and energy dispersive X-ray detection (EDS and X-ray diffraction (XRD analyses were performed to confirm the oxide composition and structure. 

Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

Directory of Open Access Journals (Sweden)

Zhiyang Li

2015-09-01

Full Text Available In this paper, vertically aligned Pt nanowire arrays (PtNWA with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H2O2 detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM−1·cm−2 among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors.

Functionalization of silicon nanowire surfaces with metal-organic frameworks

KAUST Repository

Liu, Nian

2011-12-28

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

Ultradense, Deep Subwavelength Nanowire Array Photovoltaics As Engineered Optical Thin Films

KAUST Repository

Tham, Douglas; Heath, James R.

2010-01-01

A photovoltaic device comprised of an array of 20 nm wide, 32 nm pitch array of silicon nanowires is modeled as an optical material. The nanowire array (NWA) has characteristic device features that are deep in the subwavelength regime for light

Effect of rapid oxidation on optical and electrical properties of silicon nanowires obtained by chemical etching

Science.gov (United States)

Karyaoui, M.; Bardaoui, A.; Ben Rabha, M.; Harmand, J. C.; Amlouk, M.

2012-05-01

In the present work, we report the investigation of passivated silicon nanowires (SiNWs) having an average radius of 3.7 μm, obtained by chemical etching of p-type silicon (p-Si). The surface passivation of the SiNWs was performed through a rapid oxidation conducted under a controlled atmosphere at different temperatures and durations. The morphology of the SiNWs was examined using a scanning electron microscope (SEM) that revealed a wave-like structure of dense and vertically aligned one-dimensional silicon nanostructures. On the other hand, optical and electrical characterizations of the SiNWs were studied using a UV-Vis-NIR spectrometer, the Fourier transform infrared spectroscopy (FTIR) and I-V measurements. The reflectance of SiNWs has been dropped to approximately 2% in comparison to that of bare p-Si. This low reflectance slightly increased after carrying out the rapid thermal annealing. The observed behavior was attributed to the formation of a SiO2 layer, as confirmed by FTIR measurements. Finally, the electrical measurements have shown that the rapid oxidation, at certain conditions, contributes to the improvement of the electrical responses of the SiNWs, which can be of great interest for photovoltaic applications.

Nanowire decorated, ultra-thin, single crystalline silicon for photovoltaic devices.

Science.gov (United States)

Aurang, Pantea; Turan, Rasit; Unalan, Husnu Emrah

2017-10-06

Reducing silicon (Si) wafer thickness in the photovoltaic industry has always been demanded for lowering the overall cost. Further benefits such as short collection lengths and improved open circuit voltages can also be achieved by Si thickness reduction. However, the problem with thin films is poor light absorption. One way to decrease optical losses in photovoltaic devices is to minimize the front side reflection. This approach can be applied to front contacted ultra-thin crystalline Si solar cells to increase the light absorption. In this work, homojunction solar cells were fabricated using ultra-thin and flexible single crystal Si wafers. A metal assisted chemical etching method was used for the nanowire (NW) texturization of ultra-thin Si wafers to compensate weak light absorption. A relative improvement of 56% in the reflectivity was observed for ultra-thin Si wafers with the thickness of 20 ± 0.2 μm upon NW texturization. NW length and top contact optimization resulted in a relative enhancement of 23% ± 5% in photovoltaic conversion efficiency.

Electron transport characteristics of silicon nanowires by metal-assisted chemical etching

Energy Technology Data Exchange (ETDEWEB)

Qi, Yangyang; Wang, Zhen; Zhang, Mingliang; Wang, Xiaodong, E-mail: xdwang@semi.ac.cn; Ji, An; Yang, Fuhua [Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 (China)

2014-03-15

The electron transport characteristics of silicon nanowires (SiNWs) fabricated by metal-assisted chemical etching with different doping concentrations were studied. By increasing the doping concentration of the starting Si wafer, the resulting SiNWs were prone to have a rough surface, which had important effects on the contact and the electron transport. A metal-semiconductor-metal model and a thermionic field emission theory were used to analyse the current-voltage (I-V) characteristics. Asymmetric, rectifying and symmetric I-V curves were obtained. The diversity of the I-V curves originated from the different barrier heights at the two sides of the SiNWs. For heavily doped SiNWs, the critical voltage was one order of magnitude larger than that of the lightly doped, and the resistance obtained by differentiating the I-V curves at large bias was also higher. These were attributed to the lower electron tunnelling possibility and higher contact barrier, due to the rough surface and the reduced doping concentration during the etching process.

Electron transport characteristics of silicon nanowires by metal-assisted chemical etching

Science.gov (United States)

Qi, Yangyang; Wang, Zhen; Zhang, Mingliang; Wang, Xiaodong; Ji, An; Yang, Fuhua

2014-03-01

The electron transport characteristics of silicon nanowires (SiNWs) fabricated by metal-assisted chemical etching with different doping concentrations were studied. By increasing the doping concentration of the starting Si wafer, the resulting SiNWs were prone to have a rough surface, which had important effects on the contact and the electron transport. A metal-semiconductor-metal model and a thermionic field emission theory were used to analyse the current-voltage (I-V) characteristics. Asymmetric, rectifying and symmetric I-V curves were obtained. The diversity of the I-V curves originated from the different barrier heights at the two sides of the SiNWs. For heavily doped SiNWs, the critical voltage was one order of magnitude larger than that of the lightly doped, and the resistance obtained by differentiating the I-V curves at large bias was also higher. These were attributed to the lower electron tunnelling possibility and higher contact barrier, due to the rough surface and the reduced doping concentration during the etching process.

Silicon nanowire-based tunneling field-effect transistors on flexible plastic substrates.

Science.gov (United States)

Lee, Myeongwon; Koo, Jamin; Chung, Eun-Ae; Jeong, Dong-Young; Koo, Yong-Seo; Kim, Sangsig

2009-11-11

A technique to implement silicon nanowire (SiNW)-based tunneling field-effect transistors (TFETs) on flexible plastic substrates is developed for the first time. The p-i-n configured Si NWs are obtained from an Si wafer using a conventional top-down CMOS-compatible technology, and they are then transferred onto the plastic substrate. Based on gate-controlled band-to-band tunneling (BTBT) as their working principle, the SiNW-based TFETs show normal p-channel switching behavior with a threshold voltage of -1.86 V and a subthreshold swing of 827 mV/dec. In addition, ambipolar conduction is observed due to the presence of the BTBT between the heavily doped p+ drain and n+ channel regions, indicating that our TFETs can operate in the n-channel mode as well. Furthermore, the BTBT generation rates for both the p-channel and n-channel operating modes are nearly independent of the bending state (strain = 0.8%) of the plastic substrate.

Silicon nanowire-based tunneling field-effect transistors on flexible plastic substrates

International Nuclear Information System (INIS)

Lee, Myeongwon; Koo, Jamin; Chung, Eun-Ae; Jeong, Dong-Young; Kim, Sangsig; Koo, Yong-Seo

2009-01-01

A technique to implement silicon nanowire (SiNW)-based tunneling field-effect transistors (TFETs) on flexible plastic substrates is developed for the first time. The p-i-n configured Si NWs are obtained from an Si wafer using a conventional top-down CMOS-compatible technology, and they are then transferred onto the plastic substrate. Based on gate-controlled band-to-band tunneling (BTBT) as their working principle, the SiNW-based TFETs show normal p-channel switching behavior with a threshold voltage of -1.86 V and a subthreshold swing of 827 mV/dec. In addition, ambipolar conduction is observed due to the presence of the BTBT between the heavily doped p + drain and n + channel regions, indicating that our TFETs can operate in the n-channel mode as well. Furthermore, the BTBT generation rates for both the p-channel and n-channel operating modes are nearly independent of the bending state (strain = 0.8%) of the plastic substrate.

Silicon nanowire-based tunneling field-effect transistors on flexible plastic substrates

Energy Technology Data Exchange (ETDEWEB)

Lee, Myeongwon; Koo, Jamin; Chung, Eun-Ae; Jeong, Dong-Young; Kim, Sangsig [Department of Electrical Engineering and Institute for Nano Science, Korea University, 5-1, Anam-Dong, Seongbuk-Gu, Seoul 136-701 (Korea, Republic of); Koo, Yong-Seo, E-mail: sangsig@korea.ac.k [Department of Electrical Engineering, Seokyeong University, 16-1, Jungneung-dong, Seongbuk-gu, Seoul 136-704 (Korea, Republic of)

2009-11-11

A technique to implement silicon nanowire (SiNW)-based tunneling field-effect transistors (TFETs) on flexible plastic substrates is developed for the first time. The p-i-n configured Si NWs are obtained from an Si wafer using a conventional top-down CMOS-compatible technology, and they are then transferred onto the plastic substrate. Based on gate-controlled band-to-band tunneling (BTBT) as their working principle, the SiNW-based TFETs show normal p-channel switching behavior with a threshold voltage of -1.86 V and a subthreshold swing of 827 mV/dec. In addition, ambipolar conduction is observed due to the presence of the BTBT between the heavily doped p{sup +} drain and n{sup +} channel regions, indicating that our TFETs can operate in the n-channel mode as well. Furthermore, the BTBT generation rates for both the p-channel and n-channel operating modes are nearly independent of the bending state (strain = 0.8%) of the plastic substrate.

Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

OpenAIRE

K?nig, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

2017-01-01

All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusi...

Fabrication of Si-based planar type patch clamp biosensor using silicon on insulator substrate

International Nuclear Information System (INIS)

Zhang, Z.L.; Asano, T.; Uno, H.; Tero, R.; Suzui, M.; Nakao, S.; Kaito, T.; Shibasaki, K.; Tominaga, M.; Utsumi, Y.; Gao, Y.L.; Urisu, T.

2008-01-01

The aim of this paper is to fabricate the planar type patch clamp ion-channel biosensor, which is suitable for the high throughput screening, using silicon-on-insulator (SOI) substrate. The micropore with 1.2 μm diameter is formed through the top Si layer and the SiO 2 box layer of the SOI substrate by focused ion beam (FIB). Then the substrate is assembled into the microfluidic circuit. The human embryonic kidney 293 (HEK-293) cell transfected with transient receptor potential vanilloid type 1 (TRPV1) is positioned on the micropore and the whole-cell configuration is formed by the suction. Capsaicin is added to the extracellular solution as a ligand molecule, and the channel current showing the desensitization unique to TRPV1 is measured successfully

Fabrication of Si-based planar type patch clamp biosensor using silicon on insulator substrate

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z.L.; Asano, T. [Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585 (Japan); Uno, H. [Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan); Tero, R. [Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585 (Japan); Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan); Suzui, M.; Nakao, S. [Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan); Kaito, T. [SII NanoTechnology Inc., 36-1, Takenoshita, Oyama-cho, Sunto-gun, Shizuoka, 410-1393 (Japan); Shibasaki, K.; Tominaga, M. [Okazaki Institute for Integrative Bioscience, 5-1, Higashiyama, Myodaiji, Okazaki, 444-8787 (Japan); Utsumi, Y. [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2, Koto, Kamigori, Ako-gun, Hyogo, 678-1205 (Japan); Gao, Y.L. [Department of Physics and Astronomy, Rochester University, Rochester, New York 14627 (United States); Urisu, T. [Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585 (Japan); Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan)], E-mail: urisu@ims.ac.jp

2008-03-03

The aim of this paper is to fabricate the planar type patch clamp ion-channel biosensor, which is suitable for the high throughput screening, using silicon-on-insulator (SOI) substrate. The micropore with 1.2 {mu}m diameter is formed through the top Si layer and the SiO{sub 2} box layer of the SOI substrate by focused ion beam (FIB). Then the substrate is assembled into the microfluidic circuit. The human embryonic kidney 293 (HEK-293) cell transfected with transient receptor potential vanilloid type 1 (TRPV1) is positioned on the micropore and the whole-cell configuration is formed by the suction. Capsaicin is added to the extracellular solution as a ligand molecule, and the channel current showing the desensitization unique to TRPV1 is measured successfully.

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

International Nuclear Information System (INIS)

Bindal, Ahmet; Hamedi-Hagh, Sotoudeh

2007-01-01

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

In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

International Nuclear Information System (INIS)

Gong Yibin; Dai Pengfei; Gao Anran; Li Tie; Zhou Ping; Wang Yuelin

2011-01-01

Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm/min) and vertical (1.7 nm/min) dimensions. A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly, yielding enhanced field effect transistor (FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart, which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality of the (111) plane, as well as the bulk depletion property should be the causes of this electrical enhancement, which implies the great potential of the as-made cost-effective SiNW FET device in many fields. (semiconductor materials)

Arrays of suspended silicon nanowires defined by ion beam implantation: mechanical coupling and combination with CMOS technology

Science.gov (United States)

Llobet, J.; Rius, G.; Chuquitarqui, A.; Borrisé, X.; Koops, R.; van Veghel, M.; Perez-Murano, F.

2018-04-01

We present the fabrication, operation, and CMOS integration of arrays of suspended silicon nanowires (SiNWs). The functional structures are obtained by a top-down fabrication approach consisting in a resistless process based on focused ion beam irradiation, causing local gallium implantation and silicon amorphization, plus selective silicon etching by tetramethylammonium hydroxide, and a thermal annealing process in a boron rich atmosphere. The last step enables the electrical functionality of the irradiated material. Doubly clamped silicon beams are fabricated by this method. The electrical readout of their mechanical response can be addressed by a frequency down-mixing detection technique thanks to an enhanced piezoresistive transduction mechanism. Three specific aspects are discussed: (i) the engineering of mechanically coupled SiNWs, by making use of the nanometer scale overhang that it is inherently-generated with this fabrication process, (ii) the statistical distribution of patterned lateral dimensions when fabricating large arrays of identical devices, and (iii) the compatibility of the patterning methodology with CMOS circuits. Our results suggest that the application of this method to the integration of large arrays of suspended SiNWs with CMOS circuitry is interesting in view of applications such as advanced radio frequency band pass filters and ultra-high-sensitivity mass sensors.

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

Energy Technology Data Exchange (ETDEWEB)

Zardo, Ilaria

2010-12-15

The present Ph.D. thesis proposes two aims: the search for catalysts alternative to gold for the growth of silicon nanowires and the investigation of the structural properties of the gold-free catalyzed Si, Ge, and GaAs nanowires. The successful growth of gold free catalyzed silicon nanowires was obtained using Ga and In as catalyst. Hydrogen plasma conditions were needed during the growth process. We proposed a growth mechanism where the role of the hydrogen plasma is taken into account. The influence of the growth conditions on nanowire growth morphology and structural properties was investigated in detail. The TEM studies showed the occurrence of different kind of twin defects depending on the nanowire growth direction. The intersection of twins in different spatial directions in <111>-oriented nanowires or the periodicity of highly dense twins in <112>-oriented nanowires leads to the formation of hexagonal domains embedded in the diamond silicon structure. A simple crystallographic model which illustrates the formation of the hexagonal phase was proposed. The presence of the hexagonal domains embedded in the diamond silicon structure was investigated also by means of Raman spectroscopy. The measured frequencies of the E2g and A1g modes were found to be in agreement with frequencies expected from phonon dispersion folding. An estimation of the percentage of hexagonal structure with respect to the cubic structure was given. The relative percentage of the two structures was found to change with growth temperature. Spatially resolved Raman scattering experiments were also realized on single Si nanowires. The lattice dynamics of gold-free catalyzed Ge and GaAs nanowires was studied by means of Raman spectroscopy. We performed spatially resolved Raman spectroscopy experiments on single crystalline- amorphous core-shell Ge nanowires. The correlation with TEM studies on nanowires grown under the same conditions and with AFM measurements realized of the same nanowires

Probing Stress States in Silicon Nanowires During Electrochemical Lithiation Using In Situ Synchrotron X-Ray Microdiffraction

Directory of Open Access Journals (Sweden)

Imran Ali

2018-04-01

Full Text Available Silicon is considered as a promising anode material for the next-generation lithium-ion battery (LIB due to its high capacity at nanoscale. However, silicon expands up to 300% during lithiation, which induces high stresses and leads to fractures. To design silicon nanostructures that could minimize fracture, it is important to understand and characterize stress states in the silicon nanostructures during lithiation. Synchrotron X-ray microdiffraction has proven to be effective in revealing insights of mechanical stress and other mechanics considerations in small-scale crystalline structures used in many important technological applications, such as microelectronics, nanotechnology, and energy systems. In the present study, an in situ synchrotron X-ray microdiffraction experiment was conducted to elucidate the mechanical stress states during the first electrochemical cycle of lithiation in single-crystalline silicon nanowires (SiNWs in an LIB test cell. Morphological changes in the SiNWs at different levels of lithiation were also studied using scanning electron microscope (SEM. It was found from SEM observation that lithiation commenced predominantly at the top surface of SiNWs followed by further progression toward the bottom of the SiNWs gradually. The hydrostatic stress of the crystalline core of the SiNWs at different levels of electrochemical lithiation was determined using the in situ synchrotron X-ray microdiffraction technique. We found that the crystalline core of the SiNWs became highly compressive (up to -325.5 MPa once lithiation started. This finding helps unravel insights about mechanical stress states in the SiNWs during the electrochemical lithiation, which could potentially pave the path toward the fracture-free design of silicon nanostructure anode materials in the next-generation LIB.

Optical and Electrical Biosensors : A Chemist's View

NARCIS (Netherlands)

Ullien, D.

2015-01-01

This thesis covers work done on silicon nanowire field effect transistors and optical microring resonators. An effort was put to develop point-of-care devices based on this platforms to facilitate rapid and reliable diagnosis of influenza A.

Two-Copy Wavelength Conversion of an 80 Gbit/s Serial Data Signal Using Cross-Phase Modulation in a Silicon Nanowire and Detailed Pump-Probe Characterisation

DEFF Research Database (Denmark)

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

2012-01-01

We experimentally demonstrate 80 Gbit/s wavelength conversion to two copies by simultaneously extracting the blue- and red-shifted sidebands from XPM in a silicon nanowire. Bit error rates of 10-9 with only ~2 dB power penalty is achieved for both sidebands. Detailed pump-probe characterisation r...

Silicon Nanowire/Polymer Hybrid Solar Cell-Supercapacitor: A Self-Charging Power Unit with a Total Efficiency of 10.5.

Science.gov (United States)

Liu, Ruiyuan; Wang, Jie; Sun, Teng; Wang, Mingjun; Wu, Changsheng; Zou, Haiyang; Song, Tao; Zhang, Xiaohong; Lee, Shuit-Tong; Wang, Zhong Lin; Sun, Baoquan

2017-07-12

An integrated self-charging power unit, combining a hybrid silicon nanowire/polymer heterojunction solar cell with a polypyrrole-based supercapacitor, has been demonstrated to simultaneously harvest solar energy and store it. By efficiency enhancement of the hybrid nanowire solar cells and a dual-functional titanium film serving as conjunct electrode of the solar cell and supercapacitor, the integrated system is able to yield a total photoelectric conversion to storage efficiency of 10.5%, which is the record value in all the integrated solar energy conversion and storage system. This system may not only serve as a buffer that diminishes the solar power fluctuations from light intensity, but also pave its way toward cost-effective high efficiency self-charging power unit. Finally, an integrated device based on ultrathin Si substrate is demonstrated to expand its feasibility and potential application in flexible energy conversion and storage devices.

Structural and photoluminescence properties of silicon nanowires extracted by means of a centrifugation process from plasma torch synthesized silicon nanopowder

Science.gov (United States)

Le Borgne, Vincent; Agati, Marta; Boninelli, Simona; Castrucci, Paola; De Crescenzi, Maurizio; Dolbec, Richard; El Khakani, My Ali

2017-07-01

We report on a method for the extraction of silicon nanowires (SiNWs) from the by-product of a plasma torch based spheroidization process of silicon. This by-product is a nanopowder which consists of a mixture of SiNWs and silicon particles. By optimizing a centrifugation based process, we were able to extract substantial amounts of highly pure Si nanomaterials (mainly SiNWs and Si nanospheres (SiNSs)). While the purified SiNWs were found to have typical outer diameters in the 10-15 nm range and lengths of up to several μm, the SiNSs have external diameters in the 10-100 nm range. Interestingly, the SiNWs are found to have a thinner Si core (2-5 nm diam.) and an outer silicon oxide shell (with a typical thickness of ˜5-10 nm). High resolution transmission electron microscopy (HRTEM) observations revealed that many SiNWs have a continuous cylindrical core, whereas others feature a discontinuous core consisting of a chain of Si nanocrystals forming a sort of ‘chaplet-like’ structures. These plasma-torch-produced SiNWs are highly pure with no trace of any metal catalyst, suggesting that they mostly form through SiO-catalyzed growth scheme rather than from metal-catalyzed path. The extracted Si nanostructures are shown to exhibit a strong photoluminescence (PL) which is found to blue-shift from 950 to 680 nm as the core size of the Si nanostructures decreases from ˜5 to ˜3 nm. This near IR-visible PL is shown to originate from quantum confinement (QC) in Si nanostructures. Consistently, the sizes of the Si nanocrystals directly determined from HRTEM images corroborate well with those expected by QC theory.

Atomic Layer Deposition Alumina-Passivated Silicon Nanowires: Probing the Transition from Electrochemical Double-Layer Capacitor to Electrolytic Capacitor.

Science.gov (United States)

Gaboriau, Dorian; Boniface, Maxime; Valero, Anthony; Aldakov, Dmitry; Brousse, Thierry; Gentile, Pascal; Sadki, Said

2017-04-19

Silicon nanowires were coated by a 1-5 nm thin alumina layer by atomic layer deposition (ALD) in order to replace poorly reproducible and unstable native silicon oxide by a highly conformal passivating alumina layer. The surface coating enabled probing the behavior of symmetric devices using such electrodes in the EMI-TFSI electrolyte, allowing us to attain a large cell voltage up to 6 V in ionic liquid, together with very high cyclability with less than 4% capacitance fade after 10 6 charge/discharge cycles. These results yielded fruitful insights into the transition between an electrochemical double-layer capacitor behavior and an electrolytic capacitor behavior. Ultimately, thin ALD dielectric coatings can be used to obtain hybrid devices exhibiting large cell voltage and excellent cycle life of dielectric capacitors, while retaining energy and power densities close to the ones displayed by supercapacitors.

Hierarchical silicon nanowires-carbon textiles matrix as a binder-free anode for high-performance advanced lithium-ion batteries

Science.gov (United States)

Liu, Bin; Wang, Xianfu; Chen, Haitian; Wang, Zhuoran; Chen, Di; Cheng, Yi-Bing; Zhou, Chongwu; Shen, Guozhen

2013-01-01

Toward the increasing demands of portable energy storage and electric vehicle applications, the widely used graphite anodes with significant drawbacks become more and more unsuitable. Herein, we report a novel scaffold of hierarchical silicon nanowires-carbon textiles anodes fabricated via a facile method. Further, complete lithium-ion batteries based on Si and commercial LiCoO2 materials were assembled to investigate their corresponding across-the-aboard performances, demonstrating their enhanced specific capacity (2950 mAh g−1 at 0.2 C), good repeatability/rate capability (even >900 mAh g−1 at high rate of 5 C), long cycling life, and excellent stability in various external conditions (curvature, temperature, and humidity). Above results light the way to principally replacing graphite anodes with silicon-based electrodes which was confirmed to have better comprehensive performances. PMID:23572030

Low-temperature grown indium oxide nanowire-based antireflection coatings for multi-crystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Wang, Yu-Cian; Chen, Chih-Yao; Chen, I Chen [Institute of Materials Science and Engineering, National Central University, Taoyuan (China); Kuo, Cheng-Wen; Kuan, Ta-Ming; Yu, Cheng-Yeh [TSEC Corporation, Hsinchu (China)

2016-08-15

Light harvesting by indium oxide nanowires (InO NWs) as an antireflection layer on multi-crystalline silicon (mc-Si) solar cells has been investigated. The low-temperature growth of InO NWs was performed in electron cyclotron resonance (ECR) plasma with an O{sub 2}-Ar system using indium nanocrystals as seed particles via the self-catalyzed growth mechanism. The size-dependence of antireflection properties of InO NWs was studied. A considerable enhancement in short-circuit current (from 35.39 to 38.33 mA cm{sup -2}) without deterioration of other performance parameters is observed for mc-Si solar cells coated with InO NWs. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Quantum Coherent States and Path Integral Method to Stochastically Determine the Anisotropic Volume Expansion in Lithiated Silicon Nanowires

Directory of Open Access Journals (Sweden)

Donald C. Boone

2017-10-01

Full Text Available This computational research study will analyze the multi-physics of lithium ion insertion into a silicon nanowire in an attempt to explain the electrochemical kinetics at the nanoscale and quantum level. The electron coherent states and a quantum field version of photon density waves will be the joining theories that will explain the electron-photon interaction within the lithium-silicon lattice structure. These two quantum particles will be responsible for the photon absorption rate of silicon atoms that are hypothesized to be the leading cause of breaking diatomic silicon covalent bonds that ultimately leads to volume expansion. It will be demonstrated through the combination of Maxwell stress tensor, optical amplification and path integrals that a stochastic analyze using a variety of Poisson distributions that the anisotropic expansion rates in the <110>, <111> and <112> orthogonal directions confirms the findings ascertained in previous works made by other research groups. The computational findings presented in this work are similar to those which were discovered experimentally using transmission electron microscopy (TEM and simulation models that used density functional theory (DFT and molecular dynamics (MD. The refractive index and electric susceptibility parameters of lithiated silicon are interwoven in the first principle theoretical equations and appears frequently throughout this research presentation, which should serve to demonstrate the importance of these parameters in the understanding of this component in lithium ion batteries.

Schottky-Gated Probe-Free ZnO Nanowire Biosensor

KAUST Repository

Yeh, Ping-Hung

2009-12-28

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

Piezoresistance of top-down suspended Si nanowires

International Nuclear Information System (INIS)

Koumela, A; Mercier, D; Dupre, C; Jourdan, G; Marcoux, C; Ollier, E; Duraffourg, L; Purcell, S T

2011-01-01

Measurements of the gauge factor of suspended, top-down silicon nanowires are presented. The nanowires are fabricated with a CMOS compatible process and with doping concentrations ranging from 2 x 10 20 down to 5 x 10 17 cm -3 . The extracted gauge factors are compared with results on identical non-suspended nanowires and with state-of-the-art results. An increase of the gauge factor after suspension is demonstrated. For the low doped nanowires a value of 235 is measured. Particular attention was paid throughout the experiments to distinguishing real resistance change due to strain modulation from resistance fluctuations due to charge trapping. Furthermore, a numerical model correlating surface charge density with the gauge factor is presented. Comparison of the simulations with experimental measurements shows the validity of this approach. These results contribute to a deeper understanding of the piezoresistive effect in Si nanowires.

InGaN/GaN Nanowire LEDs and Lasers

KAUST Repository

Zhao, Chao

2016-01-01

The large specific surface, and the associated high density of surface states was found to limit the light output power and quantum efficiency of nanowire-array devices, despite their potential for addressing the “green-gap” and efficiency-droop issues. The phonon and carrier confinement in nanowires also led to junction heating, and reduced heat dissipation. In this paper, we will present our studies on effective surface states passivation in InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) and lasers grown on silicon (Si), as well as our recent work on nanowires LEDs grown on bulk-metal, a non-conventional substrate.

Synthesis and analysis of silicon nanowire below Si-Au eutectic temperatures using very high frequency plasma enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Hamidinezhad, Habib; Wahab, Yussof; Othaman, Zulkafli; Ismail, Abd Khamim

2011-01-01

Silicon nanowires (SiNWs) were synthesized from pure silane precursor gas and Au nanoparticles catalyst at below Au-Si eutectic temperature. The SiNWs were grown onto Si (1 1 1) substrates using very high frequency plasma enhanced chemical vapor deposition via a vapor-solid-solid mechanism at temperatures ranging from 363 to 230 deg. C. The morphology of the synthesized SiNWs was characterized by means of field emission scanning electron microscope equipped with energy dispersive X-ray, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscope. Results demonstrated that the SiNWs can be grown at the temperature as low as 250 deg. C. In addition, it was revealed that the grown wires were silicon-crystallized.

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.

Optical properties of nanowire metamaterials with gain

DEFF Research Database (Denmark)

Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi

2016-01-01

The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide....... The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

Effects of lithium insertion on thermal conductivity of silicon nanowires

International Nuclear Information System (INIS)

Xu, Wen; Zhang, Gang; Li, Baowen

2015-01-01

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

Electron transport characteristics of silicon nanowires by metal-assisted chemical etching

Directory of Open Access Journals (Sweden)

Yangyang Qi

2014-02-01

Full Text Available The electron transport characteristics of silicon nanowires (SiNWs fabricated by metal-assisted chemical etching with different doping concentrations were studied. By increasing the doping concentration of the starting Si wafer, the resulting SiNWs were prone to have a rough surface, which had important effects on the contact and the electron transport. A metal-semiconductor-metal model and a thermionic field emission theory were used to analyse the current-voltage (I-V characteristics. Asymmetric, rectifying and symmetric I-V curves were obtained. The diversity of the I-V curves originated from the different barrier heights at the two sides of the SiNWs. For heavily doped SiNWs, the critical voltage was one order of magnitude larger than that of the lightly doped, and the resistance obtained by differentiating the I-V curves at large bias was also higher. These were attributed to the lower electron tunnelling possibility and higher contact barrier, due to the rough surface and the reduced doping concentration during the etching process.

Self-assembly of silicon nanowires studied by advanced transmission electron microscopy

Directory of Open Access Journals (Sweden)

Marta Agati

2017-02-01

Full Text Available Scanning transmission electron microscopy (STEM was successfully applied to the analysis of silicon nanowires (SiNWs that were self-assembled during an inductively coupled plasma (ICP process. The ICP-synthesized SiNWs were found to present a Si–SiO2 core–shell structure and length varying from ≈100 nm to 2–3 μm. The shorter SiNWs (maximum length ≈300 nm were generally found to possess a nanoparticle at their tip. STEM energy dispersive X-ray (EDX spectroscopy combined with electron tomography performed on these nanostructures revealed that they contain iron, clearly demonstrating that the short ICP-synthesized SiNWs grew via an iron-catalyzed vapor–liquid–solid (VLS mechanism within the plasma reactor. Both the STEM tomography and STEM-EDX analysis contributed to gain further insight into the self-assembly process. In the long-term, this approach might be used to optimize the synthesis of VLS-grown SiNWs via ICP as a competitive technique to the well-established bottom-up approaches used for the production of thin SiNWs.

Defect level characterization of silicon nanowire arrays: Towards novel experimental paradigms

Energy Technology Data Exchange (ETDEWEB)

Carapezzi, Stefania; Castaldini, Antonio; Cavallini, Anna [Department of Physics and Astronomy, University of Bologna, V.le Berti Pichat 6/2, Bologna (Italy); Irrera, Alessia [IPCF CNR, Viale Stagno D' Alcontres n. 37-98158, Messina, Italy and MATIS IMM CNR, Viale Santa Sofia n. 64, 95123 Catania (Italy)

2014-02-21

The huge amount of knowledge, and infrastructures, brought by silicon (Si) technology, make Si Nanowires (NWs) an ideal choice for nano-electronic Si-based devices. This, in turn, challenges the scientific research to adapt the technical and theoretical paradigms, at the base of established experimental techniques, in order to probe the properties of these systems. Metal-assisted wet-Chemical Etching (MaCE) [1, 2] is a promising fast, easy and cheap method to grow high aspect-ratio aligned Si NWs. Further, contrary to other fabrication methods, this method avoids the possible detrimental effects related to Au diffusion into NWs. We investigated the bandgap level diagram of MaCE Si NW arrays, phosphorous-doped, by means of Deep Level Transient Spectroscopy. The presence of both shallow and deep levels has been detected. The results have been examined in the light of the specificity of the MaCE growth. The study of the electronic levels in Si NWs is, of course, of capital importance in view of the integration of Si NW arrays as active layers in actual devices.

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-03-15

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

Metal-coated microfluidic channels: An approach to eliminate streaming potential effects in nano biosensors.

Science.gov (United States)

Lee, Jieun; Wipf, Mathias; Mu, Luye; Adams, Chris; Hannant, Jennifer; Reed, Mark A

2017-01-15

We report a method to suppress streaming potential using an Ag-coated microfluidic channel on a p-type silicon nanowire (SiNW) array measured by a multiplexed electrical readout. The metal layer sets a constant electrical potential along the microfluidic channel for a given reference electrode voltage regardless of the flow velocity. Without the Ag layer, the magnitude and sign of the surface potential change on the SiNW depends on the flow velocity, width of the microfluidic channel and the device's location inside the microfluidic channel with respect to the reference electrode. Noise analysis of the SiNW array with and without the Ag coating in the fluidic channel shows that noise frequency peaks, resulting from the operation of a piezoelectric micropump, are eliminated using the Ag layer with two reference electrodes located at inlet and outlet. This strategy presents a simple platform to eliminate the streaming potential and can become a powerful tool for nanoscale potentiometric biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrothermal growth of titania nanowires for SAW device sensing area

Directory of Open Access Journals (Sweden)

Zakaria Mohd Rosydi

2017-01-01

Full Text Available Synthesis of titania or titanium dioxide (TiO2 is attracted to energy and environmental applications. Here, the growth of nanostructure TiO2 nanowires on Si (100 substrates by using the two-step method. Different seed layers of TiO2 were deposited by spin coating and annealing, followed by the growth of TiO2 nanowires by using the hydrothermal method. The sol-gel technique was used in preparing the TiO2 solution for the thin film deposition purpose. Acetic acid, hydrochloric acid and tris (2-aminoethyl amine were used as a stabilizer to synthesize three different TiO2 seed layers. The aim of this study was to understand the role of polycrystalline size on thin film towards the diameter of nanowires grown as a sensing area in Surface Acoustic Wave (SAW Biosensor. The morphology and structure of the thin film and TiO2 nanowires were characterized using X-Ray diffraction (XRD, scanning electron microscope (SEM, field emission scanning electron microscope (FESEM and atomic force microscopy (AFM.

Droop-free AlxGa1-xN/AlyGa1-yN quantum-disks-in-nanowires ultraviolet LED emitting at 337 nm on metal/silicon substrates

KAUST Repository

Janjua, Bilal

2017-01-18

Currently the AlGaN-based ultraviolet (UV) solid-state lighting research suffers from numerous challenges. In particular, low internal quantum efficiency, low extraction efficiency, inefficient doping, large polarization fields, and high dislocation density epitaxy constitute bottlenecks in realizing high power devices. Despite the clear advantage of quantum-confinement nanostructure, it has not been widely utilized in AlGaN-based nanowires. Here we utilize the self-assembled nanowires (NWs) with embedding quantum-disks (Qdisks) to mitigate these issues, and achieve UV emission of 337 nm at 32 A/cm (80 mA in 0.5 × 0.5 mm device), a turn-on voltage of ∼5.5 V and droop-free behavior up to 120 A/cm of injection current. The device was grown on a titanium-coated n-type silicon substrate, to improve current injection and heat dissipation. A narrow linewidth of 11.7 nm in the electroluminescence spectrum and a strong wavefunctions overlap factor of 42% confirm strong quantum confinement within uniformly formed AlGaN/AlGaN Qdisks, verified using transmission electron microscopy (TEM). The nitride-based UV nanowires light-emitting diodes (NWs-LEDs) grown on low cost and scalable metal/silicon template substrate, offers a scalable, environment friendly and low cost solution for numerous applications, such as solid-state lighting, spectroscopy, medical science and security.

Droop-free AlxGa1-xN/AlyGa1-yN quantum-disks-in-nanowires ultraviolet LED emitting at 337 nm on metal/silicon substrates

KAUST Repository

Janjua, Bilal; Sun, Haiding; Zhao, Chao; Anjum, Dalaver H.; Priante, Davide; Alhamoud, Abdullah A.; Wu, Feng-Yu; Li, Xiaohang; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ng, Tien Khee; Ooi, Boon S.

2017-01-01

Currently the AlGaN-based ultraviolet (UV) solid-state lighting research suffers from numerous challenges. In particular, low internal quantum efficiency, low extraction efficiency, inefficient doping, large polarization fields, and high dislocation density epitaxy constitute bottlenecks in realizing high power devices. Despite the clear advantage of quantum-confinement nanostructure, it has not been widely utilized in AlGaN-based nanowires. Here we utilize the self-assembled nanowires (NWs) with embedding quantum-disks (Qdisks) to mitigate these issues, and achieve UV emission of 337 nm at 32 A/cm (80 mA in 0.5 × 0.5 mm device), a turn-on voltage of ∼5.5 V and droop-free behavior up to 120 A/cm of injection current. The device was grown on a titanium-coated n-type silicon substrate, to improve current injection and heat dissipation. A narrow linewidth of 11.7 nm in the electroluminescence spectrum and a strong wavefunctions overlap factor of 42% confirm strong quantum confinement within uniformly formed AlGaN/AlGaN Qdisks, verified using transmission electron microscopy (TEM). The nitride-based UV nanowires light-emitting diodes (NWs-LEDs) grown on low cost and scalable metal/silicon template substrate, offers a scalable, environment friendly and low cost solution for numerous applications, such as solid-state lighting, spectroscopy, medical science and security.

Improved sensing characteristics of dual-gate transistor sensor using silicon nanowire arrays defined by nanoimprint lithography

Science.gov (United States)

Lim, Cheol-Min; Lee, In-Kyu; Lee, Ki Joong; Oh, Young Kyoung; Shin, Yong-Beom; Cho, Won-Ju

2017-12-01

This work describes the construction of a sensitive, stable, and label-free sensor based on a dual-gate field-effect transistor (DG FET), in which uniformly distributed and size-controlled silicon nanowire (SiNW) arrays by nanoimprint lithography act as conductor channels. Compared to previous DG FETs with a planar-type silicon channel layer, the constructed SiNW DG FETs exhibited superior electrical properties including a higher capacitive-coupling ratio of 18.0 and a lower off-state leakage current under high-temperature stress. In addition, while the conventional planar single-gate (SG) FET- and planar DG FET-based pH sensors showed the sensitivities of 56.7 mV/pH and 439.3 mV/pH, respectively, the SiNW DG FET-based pH sensors showed not only a higher sensitivity of 984.1 mV/pH, but also a lower drift rate of 0.8% for pH-sensitivity. This demonstrates that the SiNW DG FETs simultaneously achieve high sensitivity and stability, with significant potential for future biosensing applications.

Surface chemistry and morphology of the solid electrolyte interphase on silicon nanowire lithium-ion battery anodes

KAUST Repository

Chan, Candace K.

2009-04-01

Silicon nanowires (SiNWs) have the potential to perform as anodes for lithium-ion batteries with a much higher energy density than graphite. However, there has been little work in understanding the surface chemistry of the solid electrolyte interphase (SEI) formed on silicon due to the reduction of the electrolyte. Given that a good, passivating SEI layer plays such a crucial role in graphite anodes, we have characterized the surface composition and morphology of the SEI formed on the SiNWs using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). We have found that the SEI is composed of reduction products similar to that found on graphite electrodes, with Li2CO3 as an important component. Combined with electrochemical impedance spectroscopy, the results were used to determine the optimal cycling parameters for good cycling. The role of the native SiO2 as well as the effect of the surface area of the SiNWs on reactivity with the electrolyte were also addressed. © 2009 Elsevier B.V. All rights reserved.

RF/microwave properties of nanotubes and nanowires : LDRD Project 105876 final report.

Energy Technology Data Exchange (ETDEWEB)

Scrymgeour, David; Lee, Mark; Hsu, Julia W. P.; Highstrete, Clark

2009-09-01

LDRD Project 105876 was a research project whose primary goal was to discover the currently unknown science underlying the basic linear and nonlinear electrodynamic response of nanotubes and nanowires in a manner that will support future efforts aimed at converting forefront nanoscience into innovative new high-frequency nanodevices. The project involved experimental and theoretical efforts to discover and understand high frequency (MHz through tens of GHz) electrodynamic response properties of nanomaterials, emphasizing nanowires of silicon, zinc oxide, and carbon nanotubes. While there is much research on DC electrical properties of nanowires, electrodynamic characteristics still represent a major new frontier in nanotechnology. We generated world-leading insight into how the low dimensionality of these nanomaterials yields sometimes desirable and sometimes problematic high-frequency properties that are outside standard model electron dynamics. In the cases of silicon nanowires and carbon nanotubes, evidence of strong disorder or glass-like charge dynamics was measured, indicating that these materials still suffer from serious inhomogeneities that limit there high frequency performance. Zinc oxide nanowires were found to obey conventional Drude dynamics. In all cases, a significant practical problem involving large impedance mismatch between the high intrinsic impedance of all nanowires and nanotubes and high-frequency test equipment had to be overcome.

GOX-functionalized nanodiamond films for electrochemical biosensor

Energy Technology Data Exchange (ETDEWEB)

Villalba, Pedro [Department of Chemical and Biomedical Engineering, University of South Florida (United States); Departamento de Medicina, Universidad del Norte, Barranquilla (Colombia); Ram, Manoj K., E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350 (United States); Nanotechnology Research and Education Center, University of South Florida (United States); Gomez, Humberto [Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350 (United States); Departamento de Medicina, Universidad del Norte, Barranquilla (Colombia); Kumar, Amrita [Department of Physiology, Emory University. Atlanta GA (United States); Bhethanabotla, Venkat [Department of Chemical and Biomedical Engineering, University of South Florida (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350 (United States); Nanotechnology Research and Education Center, University of South Florida (United States)

2011-07-20

The importance of nanodiamond in biological and technological applications has been recognized recently, and applied in drug delivery, biochip, sensors and biosensors. Under this investigation, nanodiamond (ND) and nitrogen doped nanodiamond (NND) were deposited on n-type silicon films, and later functionalized with enzyme Glucose oxidase (GOX). The GOX functionalized doped and undoped ND films were characterized using combination of several techniques; i.e. FTIR spectroscopy, Raman spectroscopy, atomic force microscopy (AFM) and electrochemical techniques. ND/GOX and NND/GOX thin films on n-type silicon have been found to provide sensitive glucose sensor. GOX has been chosen as a model enzyme system to functionalize with ND at molecular level to understand the glucose biosensor. - Research highlights: {yields} Nanodiamond (ND) films were used as an enzyme electrode for glucose quantification. {yields} Electrochemical behavior of doped and intrinsic films was analyzed. {yields} Electrode demonstrates sensitivity to glucose concentration in dynamic condition. {yields} Linear behavior was observed upto 8mM before saturation condition.

GOX-functionalized nanodiamond films for electrochemical biosensor

International Nuclear Information System (INIS)

Villalba, Pedro; Ram, Manoj K.; Gomez, Humberto; Kumar, Amrita; Bhethanabotla, Venkat; Kumar, Ashok

2011-01-01

The importance of nanodiamond in biological and technological applications has been recognized recently, and applied in drug delivery, biochip, sensors and biosensors. Under this investigation, nanodiamond (ND) and nitrogen doped nanodiamond (NND) were deposited on n-type silicon films, and later functionalized with enzyme Glucose oxidase (GOX). The GOX functionalized doped and undoped ND films were characterized using combination of several techniques; i.e. FTIR spectroscopy, Raman spectroscopy, atomic force microscopy (AFM) and electrochemical techniques. ND/GOX and NND/GOX thin films on n-type silicon have been found to provide sensitive glucose sensor. GOX has been chosen as a model enzyme system to functionalize with ND at molecular level to understand the glucose biosensor. - Research highlights: → Nanodiamond (ND) films were used as an enzyme electrode for glucose quantification. → Electrochemical behavior of doped and intrinsic films was analyzed. → Electrode demonstrates sensitivity to glucose concentration in dynamic condition. → Linear behavior was observed upto 8mM before saturation condition.

Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

International Nuclear Information System (INIS)

Yu, Zhongwei; Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji; Misra, Soumyadeep; Roca i Cabarrocas, Pere; Yu, Linwei

2015-01-01

Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

Fabrication and morphology of uniaxially aligned perylenediimide nanowires

Science.gov (United States)

Machida, Shinjiro; Tanikatsu, Makoto; Itaya, Akira; Ikeda, Noriaki

2017-06-01

Uniaxial alignment of crystalline nanowires consisting of N,N‧-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) was achieved on poly(tetrafluoroethylene) (PTFE) layers prepared by friction transfer method on a glass substrate. The nanowires were formed by spin-coating a trifluoroacetic acid (TFA) solution of PTCDI-C8 on the PTFE layers and were further grown under TFA vapor atmosphere. The morphology of the PTCDI-C8 nanowires were characterized using atomic force microscope (AFM) and fluorescence optical microscope with changing the dye concentration in the spin coating solution, annealing time in the TFA vapor, and substrate materials. The nanowires prepared on the PTFE layer on a silica-coated silicon or a mica substrate did not grow so well as those on the glass substrate. This result suggests that the surface roughness would affect the PTFE layer and the growth of the PTCDI nanowires.

Loose-fit graphitic encapsulation of silicon nanowire for one-dimensional Si anode design

Institute of Scientific and Technical Information of China (English)

Seh-Yoon Lim; Sudong Chae; Su-Ho Jung; Yuhwan Hyeon; Wonseok Jang; Won-Sub Yoon; Jae-Young Choi; Dongmok Whang

2017-01-01

Silicon nanowires (SiNWs) encapsulated with graphene-like carbon sheath (GS) having a void space in between (SiNW@V@GS) are demonstrated for the improved electrochemical performance of Si anode in lithium ion battery.The SiNW@V@GS structure was synthesized by a scalable fabrication method including four successive reactions:metal-catalyzed CVD growth of SiNWs,controlled thermal oxidation,and deposition of the graphitic layer,to form SiNW@SiO2@GS and additional chemical etching of sacrificial SiO2 layer between SiNWs and carbon sheath.During the synthetic process,the thickness of the void spacing was controlled by adjusting the oxidation-dependent process.The well-controlled void space and crystalline graphitic carbon sheath of the SiNW@V@GS structure enable good reversible capacity of 1444 mAhg-1 and cycling stability of 85％ over 150 cycles.

Ultra-Fast Optical Signal Processing in Nonlinear Silicon Waveguides

DEFF Research Database (Denmark)

Oxenløwe, Leif Katsuo; Galili, Michael; Pu, Minhao

2011-01-01

We describe recent demonstrations of exploiting highly nonlinear silicon nanowires for processing Tbit/s optical data signals. We perform demultiplexing and optical waveform sampling of 1.28 Tbit/s and wavelength conversion of 640 Gbit/s data signals.......We describe recent demonstrations of exploiting highly nonlinear silicon nanowires for processing Tbit/s optical data signals. We perform demultiplexing and optical waveform sampling of 1.28 Tbit/s and wavelength conversion of 640 Gbit/s data signals....

Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

International Nuclear Information System (INIS)

Chen, Wanghua; Roca i Cabarrocas, Pere; Pareige, Philippe; Castro, Celia; Xu, Tao; Grandidier, Bruno; Stiévenard, Didier

2015-01-01

By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process

Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

Chen, Wanghua; Roca i Cabarrocas, Pere [Laboratoire de Physique des Interfaces et Couches Minces (LPICM), UMR 7647, CNRS, Ecole Polytechnique, 91128 Palaiseau (France); Pareige, Philippe; Castro, Celia [Groupe de Physique des Matériaux (GPM), Université et INSA de Rouen, UMR 6634, CNRS, Av. de l' Université, BP 12, 76801 Saint Etienne du Rouvray (France); Xu, Tao; Grandidier, Bruno; Stiévenard, Didier [Institut d' Electronique et de Microélectronique et de Nanotechnologies (IEMN), UMR 8520, CNRS, Département ISEN, 41 bd Vauban, 59046 Lille Cedex (France)

2015-09-14

By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process.

{Ni4O4} Cluster Complex to Enhance the Reductive Photocurrent Response on Silicon Nanowire Photocathodes

Directory of Open Access Journals (Sweden)

Yatin J. Mange

2017-02-01

Full Text Available Metal organic {Ni4O4} clusters, known oxidation catalysts, have been shown to provide a valuable route in increasing the photocurrent response on silicon nanowire (SiNW photocathodes. {Ni4O4} clusters have been paired with SiNWs to form a new photocathode composite for water splitting. Under AM1.5 conditions, the combination of {Ni4O4} clusters with SiNWs gave a current density of −16 mA/cm2, which corresponds to an increase in current density of 60% when compared to bare SiNWs. The composite electrode was fully characterised and shown to be an efficient and stable photocathode for water splitting.

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

Energy Technology Data Exchange (ETDEWEB)

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

2009-02-25

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

Ab initio vibrations in nonequilibrium nanowires

DEFF Research Database (Denmark)

Jauho, Antti-Pekka; Engelund, Mads; Markussen, T

2010-01-01

We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative predicti...

Modeling nanowire and double-gate junctionless field-effect transistors

CERN Document Server

Jazaeri, Farzan

2018-01-01

The first book on the topic, this is a comprehensive introduction to the modeling and design of junctionless field effect transistors (FETs). Beginning with a discussion of the advantages and limitations of the technology, the authors also provide a thorough overview of published analytical models for double-gate and nanowire configurations, before offering a general introduction to the EPFL charge-based model of junctionless FETs. Important features are introduced gradually, including nanowire versus double-gate equivalence, technological design space, junctionless FET performances, short channel effects, transcapacitances, asymmetric operation, thermal noise, interface traps, and the junction FET. Additional features compatible with biosensor applications are also discussed. This is a valuable resource for students and researchers looking to understand more about this new and fast developing field.

Biosensor for detection of dissolved chromium in potable water: A review.

Science.gov (United States)

Biswas, Puja; Karn, Abhinav Kumar; Balasubramanian, P; Kale, Paresh G

2017-08-15

The unprecedented deterioration rate of the environmental quality due to rapid urbanization and industrialization causes a severe global health concern to both ecosystem and humanity. Heavy metals are ubiquitous in nature and being used extensively in industrial processes, the exposure to excessive levels could alter the biochemical cycles of living systems. Hence the environmental monitoring through rapid and specific detection of heavy metal contamination in potable water is of paramount importance. Various standard analytical techniques and sensors are used for the detection of heavy metals include spectroscopy and chromatographic methods along with electrochemical, optical waveguide and polymer based sensors. However, the mentioned techniques lack the point of care application as it demands huge capital cost as well as the attention of expert personnel for sample preparation and operation. Recent advancements in the synergetic interaction among biotechnology and microelectronics have advocated the biosensor technology for a wide array of applications due to its characteristic features of sensitivity and selectivity. This review paper has outlined the overview of chromium toxicity, conventional analytical techniques along with a particular emphasis on electrochemical based biosensors for chromium detection in potable water. This article emphasized porous silicon as a host material for enzyme immobilization and elaborated the working principle, mechanism, kinetics of an enzyme-based biosensor for chromium detection. The significant characteristics such as pore size, thickness, and porosity make the porous silicon suitable for enzyme entrapment. Further, several schemes on porous silicon-based immobilized enzyme biosensors for the detection of chromium in potable water are proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Field-emission property of self-purification SiC/SiOx coaxial nanowires synthesized via direct microwave irradiation using iron-containing catalyst

Science.gov (United States)

Zhou, Qing; Yu, Yongzhi; Huang, Shan; Meng, Jiang; Wang, Jigang

2017-07-01

SiC/SiOx coaxial nanowires were rapidly synthesized via direct microwave irradiation in low vacuum atmosphere. During the preparation process, only graphite, silicon, silicon dioxide powders were used as raw materials and iron-containing substance was employed as catalyst. Comprehensive characterizations were employed to investigate the microstructure of the products. The results showed that a great quantity of coaxial nanowires with uniform sizes and high aspect ratio had been successfully achieved. The coaxial nanowires consist of a silicon oxide (SiOx) shell and a β-phase silicon carbide (β-SiC) core that exhibited in special tube brush like. In additional, nearly all the products were achieved in the statement of pure SiC/SiOx coaxial nanowires without the existence of metallic catalyst, indicating that the self-removal of iron (Fe) catalyst should be occurred during the synthesis process. Photoluminescence (PL) spectral analysis result indicated that such novel SiC/SiOx coaxial nanowires exhibited significant blue-shift. Besides, the measurement results of field-emission (FE) demonstrated that the SiC/SiOx coaxial nanowires had ultralow turn-on field and threshold field with values of 0.2 and 2.1 V/μm, respectively. The hetero-junction structure formed between SiOx shell and SiC core, lots of emission sites, as well as clear tips of the nanowires were applied to explain the excellent FE properties.[Figure not available: see fulltext.

Comparison of the top-down and bottom-up approach to fabricate nanowire-based Silicon/Germanium heterostructures

International Nuclear Information System (INIS)

Wolfsteller, A.; Geyer, N.; Nguyen-Duc, T.-K.; Das Kanungo, P.; Zakharov, N.D.; Reiche, M.; Erfurth, W.; Blumtritt, H.; Werner, P.; Goesele, U.

2010-01-01

Silicon nanowires (NWs) and vertical nanowire-based Si/Ge heterostructures are expected to be building blocks for future devices, e.g. field-effect transistors or thermoelectric elements. In principle two approaches can be applied to synthesise these NWs: the 'bottom-up' and the 'top-down' approach. The most common method for the former is the vapour-liquid-solid (VLS) mechanism which can also be applied to grow NWs by molecular beam epitaxy (MBE). Although MBE allows a precise growth control under highly reproducible conditions, the general nature of the growth process via a eutectic droplet prevents the synthesis of heterostructures with sharp interfaces and high Ge concentrations. We compare the VLS NW growth with two different top-down methods: The first is a combination of colloidal lithography and metal-assisted wet chemical etching, which is an inexpensive and fast method and results in large arrays of homogenous Si NWs with adjustable diameters down to 50 nm. The second top-down method combines the growth of Si/Ge superlattices by MBE with electron beam lithography and reactive ion etching. Again, large and homogeneous arrays of NWs were created, this time with a diameter of 40 nm and the Si/Ge superlattice inside.

FDTD modeling of solar energy absorption in silicon branched nanowires.

Science.gov (United States)

Lundgren, Christin; Lopez, Rene; Redwing, Joan; Melde, Kathleen

2013-05-06

Thin film nanostructured photovoltaic cells are increasing in efficiency and decreasing the cost of solar energy. FDTD modeling of branched nanowire 'forests' are shown to have improved optical absorption in the visible and near-IR spectra over nanowire arrays alone, with a factor of 5 enhancement available at 1000 nm. Alternate BNW tree configurations are presented, achieving a maximum absorption of over 95% at 500 nm.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-05-26

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

Dielectrophoretic alignment of metal and metal oxide nanowires and nanotubes: a universal set of parameters for bridging prepatterned microelectrodes.

Science.gov (United States)

Maijenburg, A W; Maas, M G; Rodijk, E J B; Ahmed, W; Kooij, E S; Carlen, E T; Blank, D H A; ten Elshof, J E

2011-03-15

Nanowires and nanotubes were synthesized from metals and metal oxides using templated cathodic electrodeposition. With templated electrodeposition, small structures are electrodeposited using a template that is the inverse of the final desired shape. Dielectrophoresis was used for the alignment of the as-formed nanowires and nanotubes between prepatterned electrodes. For reproducible nanowire alignment, a universal set of dielectrophoresis parameters to align any arbitrary nanowire material was determined. The parameters include peak-to-peak potential and frequency, thickness of the silicon oxide layer, grounding of the silicon substrate, and nature of the solvent medium used. It involves applying a field with a frequency >10(5) Hz, an insulating silicon oxide layer with a thickness of 2.5 μm or more, grounding of the underlying silicon substrate, and the use of a solvent medium with a low dielectric constant. In our experiments, we obtained good results by using a peak-to-peak potential of 2.1 V at a frequency of 1.2 × 10(5) Hz. Furthermore, an indirect alignment technique is proposed that prevents short circuiting of nanowires after contacting both electrodes. After alignment, a considerably lower resistivity was found for ZnO nanowires made by templated electrodeposition (2.2-3.4 × 10(-3) Ωm) compared to ZnO nanorods synthesized by electrodeposition (10 Ωm) or molecular beam epitaxy (MBE) (500 Ωm). Copyright © 2010 Elsevier Inc. All rights reserved.