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Sample records for silicon nanowire biosensor

  1. Silicon-on-Insulator Nanowire Based Optical Waveguide Biosensors

    Science.gov (United States)

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

    2016-01-01

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

  2. A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor

    Science.gov (United States)

    2015-07-21

    Hybrid Biosensor Jieun Lee1,2, Jaeman Jang1, Bongsik Choi1, Jinsu Yoon1, Jee-Yeon Kim3, Yang-Kyu Choi3, Dong Myong Kim1, Dae Hwan Kim1 & Sung-Jin Choi1...This study demonstrates a hybrid biosensor comprised of a silicon nanowire (SiNW) integrated with an amplifier MOSFET to improve the current response...of field-effect-transistor (FET)-based biosensors . The hybrid biosensor is fabricated using conventional CMOS technology, which has the potential

  3. MMP-2 detective silicon nanowire biosensor using enzymatic cleavage reaction.

    Science.gov (United States)

    Choi, Jin-Ha; Kim, Han; Kim, Hyun-Soo; Um, Soong Ho; Choi, Jeong-Woo; Oh, Byung-Keun

    2013-04-01

    Matrix metalloproteinases are proteolytic enzymes that play a significant role in tissue remodeling related with various pathological and physiological processes such as tissue repair, angiogenesis, cirrhosis, morphogenesis, arthritis, and metastasis. Especially, MMP-2 has been shown to be related with benign prostatic hyperplasia and prostate cancer. Therefore, there is a need to make sensors with high sensitivity that can measure MMP-2 concentrations precisely. Silicon nanowires have been used in the development of high sensitive chemical sensors and biosensors. The high sensitivity of silicon nanowire based sensor originates in its high surface to volume ratio and ability to field-effect induced local charge transfers. In this study, 100 nm silicon nanowire based field-effect transistors (FET) device was fabricated by electron-beam lithography and MMP-2 was successfully measured by conductance versus time characteristics within 1 pM to 100 nM.

  4. Optical biosensor based on silicon nanowire ridge waveguide

    Science.gov (United States)

    Gamal, Rania; Ismail, Yehia; Swillam, Mohamed A.

    2015-02-01

    Optical biosensors present themselves as an attractive solution for integration with the ever-trending lab-on-a-chip devices. This is due to their small size, CMOS compatibility, and invariance to electromagnetic interference. Despite their many benefits, typical optical biosensors rely on evanescent field detection, where only a small portion of the light interacts with the analyte. We propose to use a silicon nanowire ridge waveguide (SNRW) for optical biosensing. This structure is comprised of an array of silicon nanowires, with the envelope of a ridge, on an insulator substrate. The SNRW maximizes the overlap between the analyte and the incident light wave by introducing voids to the otherwise bulk structure, and strengthens the contribution of the material under test to the overall modal effective index will greatly augment the sensitivity. Additionally, the SNRW provides a fabrication convenience as it covers the entire substrate, ensuring that the etching process would not damage the substrate. FDTD simulations were conducted and showed that the percentage change in the effective index due to a 1% change in the surrounding environment was more than 170 times the amount of change perceived in an evanescent detection based bulk silicon ridge waveguide.

  5. Specific and selective target detection of supra-genome 21 Mers Salmonella via silicon nanowires biosensor

    Science.gov (United States)

    Mustafa, Mohammad Razif Bin; Dhahi, Th S.; Ehfaed, Nuri. A. K. H.; Adam, Tijjani; Hashim, U.; Azizah, N.; Mohammed, Mohammed; Noriman, N. Z.

    2017-09-01

    The nano structure based on silicon can be surface modified to be used as label-free biosensors that allow real-time measurements. The silicon nanowire surface was functionalized using 3-aminopropyltrimethoxysilane (APTES), which functions as a facilitator to immobilize biomolecules on the silicon nanowire surface. The process is simple, economical; this will pave the way for point-of-care applications. However, the surface modification and subsequent detection mechanism still not clear. Thus, study proposed step by step process of silicon nano surface modification and its possible in specific and selective target detection of Supra-genome 21 Mers Salmonella. The device captured the molecule with precisely; the approach took the advantages of strong binding chemistry created between APTES and biomolecule. The results indicated how modifications of the nanowires provide sensing capability with strong surface chemistries that can lead to specific and selective target detection.

  6. Recent Advances in Silicon Nanowire Biosensors: Synthesis Methods, Properties, and Applications

    Science.gov (United States)

    Namdari, Pooria; Daraee, Hadis; Eatemadi, Ali

    2016-09-01

    The application of silicon nanowire (SiNW) biosensor as a subtle, label-free, and electrical tool has been extensively demonstrated by several researchers over the past few decades. Human ability to delicately fabricate and control its chemical configuration, morphology, and arrangement either separately or in combination with other materials as lead to the development of a nanomaterial with specific and efficient electronic and catalytic properties useful in the fields of biological sciences and renewable energy. This review illuminates on the various synthetic methods of SiNW, with its optical and electrical properties that make them one of the most applicable nanomaterials in the field of biomolecule sensing, photoelectrochemical conversion, and diseases diagnostics.

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

    Science.gov (United States)

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

    2015-04-01

    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.

  8. Silicon nanowires as field-effect transducers for biosensor development: a review.

    Science.gov (United States)

    Noor, M Omair; Krull, Ulrich J

    2014-05-12

    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 (>100mM). 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Enhanced sensing of dengue virus DNA detection using O2plasma treated-silicon nanowire based electrical biosensor.

    Science.gov (United States)

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

    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 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 -14  M with a linear detection range of the sequence-specific DNA from 1.0 × 10 -9  M to 1.0 × 10 -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. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. 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.

  11. Enhanced sensing of dengue virus DNA detection using O2 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 −14  M with a linear detection range of the sequence-specific DNA from 1.0 × 10 −9  M to 1.0 × 10 −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 (LoD) as low as 1.985

  12. 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

  13. Silicon nanowire hybrid photovoltaics

    KAUST Repository

    Garnett, Erik C.

    2010-06-01

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

  14. Porous Silicon Nanowires

    Science.gov (United States)

    Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

    2011-01-01

    In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline porous silicon nanowires. The growth of porous silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The porous silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999

  15. The electrophotonic silicon biosensor

    Science.gov (United States)

    Juan-Colás, José; Parkin, Alison; Dunn, Katherine E.; Scullion, Mark G.; Krauss, Thomas F.; Johnson, Steven D.

    2016-09-01

    The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale.

  16. 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...

  17. Silicon Nanowire as Virus Sensor in a Total Analysis System

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Jørgensen, Michael; Andresen, Lars

    2011-01-01

    Silicon nanowires are very promising candidates for the sensitive detection of viruses or even early detection of cancer. Due to their small dimensions the attachment of even one particle on their surface leads to detectable changes in their conductivity. In this paper we describe the development...... (fabrication and testing) of a silicon nanowire biosensor equipped with microfludic channels and automatized data aquisition for the detection of antibodies against a small virus (Aleutian Disease Virus) causing plasmacytosis on mink and ferrets....

  18. 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

  19. Semiconducting silicon nanowires for biomedical applications

    CERN Document Server

    Coffer, JL

    2014-01-01

    Biomedical applications have benefited greatly from the increasing interest and research into semiconducting silicon nanowires. Semiconducting Silicon Nanowires for Biomedical Applications reviews the fabrication, properties, and applications of this emerging material. The book begins by reviewing the basics, as well as the growth, characterization, biocompatibility, and surface modification, of semiconducting silicon nanowires. It goes on to focus on silicon nanowires for tissue engineering and delivery applications, including cellular binding and internalization, orthopedic tissue scaffol

  20. Optical absorption of silicon nanowires

    International Nuclear Information System (INIS)

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stiévenard, D.; Lévêque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-01-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  1. Nanodevices based on silicon nanowires.

    Science.gov (United States)

    Wan, Yuting; Sha, Jian; Chen, Bo; Fang, Yanjun; Wang, Zongli; Wang, Yewu

    2009-01-01

    Silicon nanowires (SiNWs) have been demonstrated as one of the promising building blocks for future nanodevices such as field effect transistors, solar cells, sensors and lithium battery; much progress has been made in this field during last decades. In this review paper, the synthesis and physical properties of SiNWs are introduced briefly. Significant advances of SiNWs-related nanodevices reported in recent literature and registered patents are reviewed. The latest development and prospects of SiNWs-related nanodevices are also discussed.

  2. Thermal conductivity reduction in silicon fishbone nanowires.

    Science.gov (United States)

    Maire, Jeremie; Anufriev, Roman; Hori, Takuma; Shiomi, Junichiro; Volz, Sebastian; Nomura, Masahiro

    2018-03-13

    Semiconductor nanowires are potential building blocks for future thermoelectrics because of their low thermal conductivity. Recent theoretical works suggest that thermal conductivity of nanowires can be further reduced by additional constrictions, pillars or wings. Here, we experimentally study heat conduction in silicon nanowires with periodic wings, called fishbone nanowires. We find that like in pristine nanowires, the nanowire cross-section controls thermal conductivity of fishbone nanowires. However, the periodic wings further reduce the thermal conductivity. Whereas an increase in the wing width only slightly affects the thermal conductivity, an increase in the wing depth clearly reduces thermal conductivity, and this reduction is stronger in the structures with narrower nanowires. Our experimental data is supported by the Callaway-Holland model, finite element modelling and phonon transport simulations.

  3. DNA hybridization on silicon nanowires

    International Nuclear Information System (INIS)

    Singh, Shalini; Zack, Jyoti; Kumar, Dinesh; Srivastava, S.K.; Govind; Saluja, Daman; Khan, M.A.; Singh, P.K.

    2010-01-01

    Nanowire-based detection strategies provide promising new routes to bioanalysis and indeed are attractive to conventional systems because of their small size, high surface-to-volume ratios, electronic, and optical properties. A sequence-specific detection of single-stranded oligonucleotides using silicon nanowires (SiNWs) is demonstrated. The surface of the SiNWs is functionalized with densely packed organic monolayer via hydrosilylation for covalent attachment. Subsequently, deoxyribonucleic acid (DNA) is immobilized to recognize the complementary target DNA. The biomolecular recognition properties of the nanowires are tested via hybridization with γ P 32 tagged complementary and non-complementary DNA oligonucleotides, showing good selectivity and reversibility. No significant non-specific binding to the incorrect sequences is observed. X-ray photoelectron spectroscopy, fluorescence imaging, and nanodrop techniques are used to characterize the modified SiNWs and covalent attachment with DNA. The results show that SiNWs are excellent substrates for the absorption, stabilization and detection of DNA sequences and could be used for DNA microarrays and micro fabricated SiNWs DNA sensors.

  4. Sensitivity and detection limit analysis of silicon nanowire bio(chemical) sensors

    NARCIS (Netherlands)

    Chen, S.; van den Berg, Albert; Carlen, Edwin

    2015-01-01

    This paper presents an analysis of the sensitivity and detection limit of silicon nanowire biosensors using an analytical model in combination with I-V and current noise measurements. The analysis shows that the limit of detection (LOD) and signal to noise ratio (SNR) can be optimized by determining

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

    Science.gov (United States)

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

    2017-04-01

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

  6. 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.

  7. 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...

  8. Titanium catalyzed silicon nanowires and nanoplatelets

    Directory of Open Access Journals (Sweden)

    Mohammad A. U. Usman

    2013-03-01

    Full Text Available Silicon nanowires, nanoplatelets, and other morphologies resulted from silicon growth catalyzed by thin titanium layers. The nanowires have diameters down to 5 nm and lengths to tens of micrometers. The two-dimensional platelets, in some instances with filigreed, snow flake-like shapes, had thicknesses down to the 10 nm scale and spans to several micrometers. These platelets grew in a narrow temperature range around 900 celsius, apparently representing a new silicon crystallite morphology at this length scale. We surmise that the platelets grow with a faceted dendritic mechanism known for larger crystals nucleated by titanium silicide catalyst islands.

  9. In-situ doped junctionless polysilicon nanowires field effect transistors for low-cost biosensors

    DEFF Research Database (Denmark)

    Zulfiqar, Azeem; Patou, François; Pfreundt, Andrea

    2017-01-01

    level at a low enough level to provide a good sensitivity for the biosensor. The silicon nanowires are patterned using standard photolithography and a wet etch method. The metal contacts are made from magnetron sputtered TiW and e-beam evaporation of gold. The passivation of electrodes has been done...... by sputtered Si3N4 which is patterned by a lift-off process. The characterization of the critical fabrication steps is done by Secondary Ion Mass Spectroscopy (SIMS) and by statistical analysis of the measurements made on the width of the SiNWs. The electrical characterization of the SiNW in air is done...

  10. In-situ doped junctionless polysilicon nanowires field effect transistors for low-cost biosensors

    Directory of Open Access Journals (Sweden)

    Azeem Zulfiqar

    2017-04-01

    Full Text Available Silicon nanowire (SiNW field effect transistor based biosensors have already been proven to be a promising tool to detect biomolecules. However, the most commonly used fabrication techniques involve expensive Silicon-On-Insulator (SOI wafers, E-beam lithography and ion-implantation steps. In the work presented here, a top down approach to fabricate SiNW junctionless field effect biosensors using novel in-situ doped polysilicon is demonstrated. The p-type polysilicon is grown with an optimum boron concentration that gives a good metal-silicon electrical contact while maintaining the doping level at a low enough level to provide a good sensitivity for the biosensor. The silicon nanowires are patterned using standard photolithography and a wet etch method. The metal contacts are made from magnetron sputtered TiW and e-beam evaporation of gold. The passivation of electrodes has been done by sputtered Si3N4 which is patterned by a lift-off process. The characterization of the critical fabrication steps is done by Secondary Ion Mass Spectroscopy (SIMS and by statistical analysis of the measurements made on the width of the SiNWs. The electrical characterization of the SiNW in air is done by sweeping the back gate voltage while keeping the source drain potential to a constant value and surface characterization is done by applying liquid gate in phosphate buffered saline (PBS solution. The fabricated SiNWs sensors functionalized with (3-aminopropyltriethoxysilane (APTES have demonstrated good sensitivity in detecting different pH buffer solutions.

  11. Multispectral imaging with vertical silicon nanowires.

    Science.gov (United States)

    Park, Hyunsung; Crozier, Kenneth B

    2013-01-01

    Multispectral imaging is a powerful tool that extends the capabilities of the human eye. However, multispectral imaging systems generally are expensive and bulky, and multiple exposures are needed. Here, we report the demonstration of a compact multispectral imaging system that uses vertical silicon nanowires to realize a filter array. Multiple filter functions covering visible to near-infrared (NIR) wavelengths are simultaneously defined in a single lithography step using a single material (silicon). Nanowires are then etched and embedded into polydimethylsiloxane (PDMS), thereby realizing a device with eight filter functions. By attaching it to a monochrome silicon image sensor, we successfully realize an all-silicon multispectral imaging system. We demonstrate visible and NIR imaging. We show that the latter is highly sensitive to vegetation and furthermore enables imaging through objects opaque to the eye.

  12. 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

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

    Science.gov (United States)

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

    2018-05-01

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

  14. 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.

  15. 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.

  16. Fabrication and properties of silicon carbide nanowires

    Science.gov (United States)

    Shim, Hyun Woo

    2008-12-01

    Silicon carbide (SiC), with excellent electrical, thermal, and mechanical properties, is a promising material candidate for future devices such as high-temperature electronics and super-strong lightweight structures. Combined with superior intrinsic properties, the nanomaterials of SiC show further advantages thanks to nanoscale effects. This thesis reports the growth mechanism, the self-integration, and the friction of SiC nanowires. The study involves nanowires fabrication using thermal evaporation, structure characterization using electron microscopy, friction measurement, and theoretical modeling. The study on nanowire growth mechanism requires understanding of the surfaces and interfaces of nanowire crystal. The catalyzed growth of SiC nanowires involves interfaces between source vapor, catalytic liquid, and nanowire solid. Our experimental observation includes the periodical twinning in a faceted SiC nanowire and three stage structure transitions during the growth. The proposed theoretical model shows that such phenomenon is the result of surface energy minimization process during the catalytic growth. Surface interactions also exist between nanowires, leading to their self-integration. Our parametric growth study reveals novel self-integration of SiC-SiO 2 core-shell nanowires as a result of SiO2 joining. Attraction between nanowires through van der Waals force and enhanced SiO2 diffusion at high temperature transform individual nanowires to the integrated nanojunctions, nanocables, and finally nanowebs. We also show that such joining process becomes effective either during growth or by annealing. The solid friction is a result of the interaction between two solid surfaces, and it depends on the adhesion and the deformation of two contacting solids among other factors. Having strong adhesion as shown from gecko foot-hairs, nanostructured materials should also have strong friction; this study is the first to investigate friction of nanostructures under

  17. Measurement of carrier mobility in silicon nanowires.

    Science.gov (United States)

    Gunawan, Oki; Sekaric, Lidija; Majumdar, Amlan; Rooks, Michael; Appenzeller, Joerg; Sleight, Jeffrey W; Guha, Supratik; Haensch, Wilfried

    2008-06-01

    We report the first direct capacitance measurements of silicon nanowires (SiNWs) and the consequent determination of field carrier mobilities in undoped-channel SiNW field-effect transistors (FETs) at room temperature. We employ a two-FET method for accurate extraction of the intrinsic channel resistance and intrinsic channel capacitance of the SiNWs. The devices used in this study were fabricated using a top-down method to create SiNW FETs with up to 1000 wires in parallel for increasing the raw capacitance while maintaining excellent control on device dimensions and series resistance. We found that, compared with the universal mobility curves for bulk silicon, the electron and hole mobilities in nanowires are comparable to those of the surface orientation that offers a lower mobility.

  18. 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.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  20. 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.

  1. 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

  2. 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.

  3. Atomic scale investigation of silicon nanowires and nanoclusters

    Directory of Open Access Journals (Sweden)

    Gourbilleau Fabrice

    2011-01-01

    Full Text Available Abstract In this study, we have performed nanoscale characterization of Si-clusters and Si-nanowires with a laser-assisted tomographic atom probe. Intrinsic and p-type silicon nanowires (SiNWs are elaborated by chemical vapor deposition method using gold as catalyst, silane as silicon precursor, and diborane as dopant reactant. The concentration and distribution of impurity (gold and dopant (boron in SiNW are investigated and discussed. Silicon nanoclusters are produced by thermal annealing of silicon-rich silicon oxide and silica multilayers. In this process, atom probe tomography (APT provides accurate information on the silicon nanoparticles and the chemistry of the nanolayers.

  4. Silicon nanowire circuits fabricated by AFM oxidation nanolithography

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, Ramses V; MartInez, Javier; Garcia, Ricardo, E-mail: rgarcia@imm.cnm.csic.es [Instituto de Microelectronica de Madrid, CSIC, Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain)

    2010-06-18

    We report a top-down process for the fabrication of single-crystalline silicon nanowire circuits and devices. Local oxidation nanolithography is applied to define very narrow oxide masks on top of a silicon-on-insulator substrate. In a plasma etching, the nano-oxide mask generates a nanowire with a rectangular section. The nanowire width coincides with the lateral size of the mask. In this way, uniform and well-defined transistors with channel widths in the 10-20 nm range have been fabricated. The nanowires can be positioned with sub-100 nm lateral accuracy. The transistors exhibit an on/off current ratio of 10{sup 5}. The atomic force microscope nanolithography offers full control of the nanowire's shape from straight to circular or a combination of them. It also enables the integration of several nanowires within the same circuit. The nanowire transistors have been applied to detect immunological processes.

  5. 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...

  6. 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.

  7. Laser direct written silicon nanowires for electronic and sensing applications

    Science.gov (United States)

    Nam, Woongsik

    Silicon nanowires are promising building blocks for high-performance electronics and chemical/biological sensing devices due to their ultra-small body and high surface-to-volume ratios. However, the lack of the ability to assemble and position nanowires in a highly controlled manner still remains an obstacle to fully exploiting the substantial potential of nanowires. Here we demonstrate a one-step method to synthesize intrinsic and doped silicon nanowires for device applications. Sub-diffraction limited nanowires as thin as 60 nm are synthesized using laser direct writing in combination with chemical vapor deposition, which has the advantages of in-situ doping, catalyst-free growth, and precise control of position, orientation, and length. The synthesized nanowires have been fabricated into field effect transistors (FETs) and FET sensors. The FET sensors are employed to detect the proton concentration (pH) of an aqueous solution and highly sensitive pH sensing is demonstrated. Both top- and back-gated silicon nanowire FETs are demonstrated and electrically characterized. In addition, modulation-doped nanowires are synthesized by changing dopant gases during the nanowire growth. The axial p-n junction nanowires are electrically characterized to demonstrate the diode behavior and the transition between dopant levels are measured using Kelvin probe force microscopy.

  8. Piezoresistive effect in top-down fabricated silicon nanowires

    DEFF Research Database (Denmark)

    Reck, Kasper; Richter, Jacob; Hansen, Ole

    2008-01-01

    resistor, each with integrated contacts for electrical 4-point measurements. We show an increase in the piezoresistive effect of 633% compared to bulk silicon. Preliminary temperature measurements indicate a larger temperature dependence of silicon nanowires, compared to bulk silicon. An increase of up...

  9. Silicon Nanowires with MoSx and Pt as Electrocatalysts for Hydrogen Evolution Reaction

    Directory of Open Access Journals (Sweden)

    S. H. Hsieh

    2016-01-01

    Full Text Available A convenient method was used for synthesizing Pt-nanoparticle/MoSx/silicon nanowires nanocomposites. Obtained Pt-MoSx/silicon nanowires electrocatalysts were characterized by transmission electron microscopy (TEM. The hydrogen evolution reaction efficiency of the Pt-MoSx/silicon nanowire nanocomposite catalysts was assessed by examining polarization and electrolysis measurements under solar light irradiations. The electrochemical characterizations demonstrate that Pt-MoSx/silicon nanowire electrodes exhibited an excellent catalytic activity for hydrogen evolution reaction in an acidic electrolyte. The hydrogen production capability of Pt-MoSx/silicon nanowires is also comparable to MoSx/silicon nanowires and Pt/silicon nanowires. Electrochemical impedance spectroscopy experiments suggest that the enhanced performance of Pt-MoSx/silicon nanowires can be attributed to the fast electron transfer between Pt-MoSx/silicon nanowire electrodes and electrolyte interfaces.

  10. Translating silicon nanowire BioFET sensor-technology to embedded point-of-care medical diagnostics

    DEFF Research Database (Denmark)

    Pfreundt, Andrea; Zulfiqar, Azeem; Patou, François

    2013-01-01

    Silicon nanowire and nanoribbon biosensors have shown great promise in the detection of biomarkers at very low concentrations. Their high sensitivity makes them ideal candidates for use in early-stage medical diagnostics and further disease monitoring where low amounts of biomarkers need to be de......Silicon nanowire and nanoribbon biosensors have shown great promise in the detection of biomarkers at very low concentrations. Their high sensitivity makes them ideal candidates for use in early-stage medical diagnostics and further disease monitoring where low amounts of biomarkers need...... rising fabrication costs. Also the translation of nano-scale sensor technology into daily-use point-of-care devices requires acknowledgement of the end-user requirements, making device portability and human-interfacing a focus point in device development. Sample handling or purification for instance...

  11. 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....

  12. Bottom-up silicon nanowire-based thermoelectric microgenerators

    Science.gov (United States)

    Dávila, D.; Huber, R.; Hierold, C.

    2015-12-01

    In this work, bottom-up intrinsic crystalline Si nanowire arrays in combination with top-down microfabrication techniques and a vertical device architecture have been proposed to develop an all-silicon nanostructured thermoelectric generator. To fabricate this device, a suitable vertical integration of Si NWs on patterned microstructures, which define the thermoelectric legs of the generator, has been achieved by bonding top and bottom silicon structures through nanowires. The process has been proven to be a feasible approach that employs a regrowth process of the nanowires for bonding purposes.

  13. Functionalization and microfluidic integration of silicon nanowire biologically gated field effect transistors

    DEFF Research Database (Denmark)

    Pfreundt, Andrea; Svendsen, Winnie Edith; Dimaki, Maria

    2016-01-01

    This thesis deals with the development of a novel biosensor for the detection of biomolecules based on a silicon nanowire biologically gated field-effect transistor and its integration into a point-of-care device. The sensor and electrical on-chip integration was developed in a different project....... The presented research is based on this sensor structure and investigates its potential as a versatile biomarker detection platform by evaluating different functionalization approaches. The functionalization of the silicon sensor surface with organic molecules was investigated in detail to determine...... the suitability of different methods for the preparation of organic interfaces for protein attachment. Oxide-free silicon surfaces offer unique possibilities to create highly sensitive sensor surfaces for charge detection due to the lack of an insulating oxide layer, but the highly reactive surface presents...

  14. Functionalization and microfluidic integration of silicon nanowire biologically gated field effect transistors

    DEFF Research Database (Denmark)

    Pfreundt, Andrea

    This thesis deals with the development of a novel biosensor for the detection of biomolecules based on a silicon nanowire biologically gated field-effect transistor and its integration into a point-of-care device. The sensor and electrical on-chip integration was developed in a different project....... The presented research is based on this sensor structure and investigates its potential as a versatile biomarker detection platform by evaluating different functionalization approaches. The functionalization of the silicon sensor surface with organic molecules was investigated in detail to determine...... the suitability of different methods for the preparation of organic interfaces for protein attachment. Oxide-free silicon surfaces offer unique possibilities to create highly sensitive sensor surfaces for charge detection due to the lack of an insulating oxide layer, but the highly reactive surface presents...

  15. 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.

  16. True reference nanosensor realized with silicon nanowires.

    Science.gov (United States)

    Tarasov, A; Wipf, M; Bedner, K; Kurz, J; Fu, W; Guzenko, V A; Knopfmacher, O; Stoop, R L; Calame, M; Schönenberger, C

    2012-06-26

    Conventional gate oxide layers (e.g., SiO(2), Al(2)O(3), or HfO(2)) in silicon field-effect transistors (FETs) provide highly active surfaces, which can be exploited for electronic pH sensing. Recently, great progress has been achieved in pH sensing using compact integrateable nanowire FETs. However, it has turned out to be much harder to realize a true reference electrode, which--while sensing the electrostatic potential--does not respond to the proton concentration. In this work, we demonstrate a highly effective reference sensor, a so-called reference FET, whose proton sensitivity is suppressed by as much as 2 orders of magnitude. To do so, the Al(2)O(3) surface of a nanowire FET was passivated with a self-assembled monolayer of silanes with a long alkyl chain. We have found that a full passivation can be achieved only after an extended period of self-assembling lasting several days at 80 °C. We use this slow process to measure the number of active proton binding sites as a function of time by a quantitative comparison of the measured nonlinear pH-sensitivities to a theoretical model (site-binding model). Furthermore, we have found that a partially passivated surface can sense small changes in the number of active binding sites reaching a detection limit of δN(s) ≈ 170 μm(-2) Hz(-1/2) at 10 Hz and pH 3.

  17. 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

  18. Nonlinear Conductive Behaviour of Silver Nanowires/Silicone Rubber Composites

    Science.gov (United States)

    Lu, Pin; Qu, Zhaoming; Wang, Qingguo; Bai, Liyun; Zhao, Shiyang

    2018-01-01

    Silver nanowires with an average length of 10 μm and diameter of about 90 nm have been synthesized by polyol reduction of silver nitrate in the presence of polyvinylpyrrolidone(PVP). Silver nanowires (AgNWs)/silicone rubber (SR) composites have been made by mixing silver nanowires into silicone rubber. The nonlinear response of AgNWs/SR composites under high electric field is investigated. The nonlinear Conductive behavior of composites is considered as a competitive process of several effects. From the perspective of the microstructure of composites, the conductive path is established by the quantum tunnel effect between silver nanowires. The influence factors on the conductivity of composites are discussed and analyzed. The results show that the AgNWs/SR composites with nonlinear conductive properties are of great potential application in electromagnetic protection of electron device and system.

  19. Highly sensitive single polyaniline nanowire biosensor for the detection of immunoglobulin G and myoglobin

    Science.gov (United States)

    Lee, Innam; Luo, Xiliang; Cui, Xinyan Tracy; Yun, Minhee

    2011-01-01

    A single polyaniline (PANI) nanowire-based biosensor was established to detect immunoglobulin G (IgG) and myoglobin (Myo), which is one of the cardiac biomarkers. The single PANI nanowires were fabricated via an electrochemical growth method, in which single nanowires were formed between a pair of patterned electrodes. The single PANI nanowires were functionalized with monoclonal antibodies (mAbs) of IgG or Myo via a surface immobilization method, using 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC), and N-Hydroxysuccinimde (NHS). The functionalization was then verified by Raman spectroscopy and fluorescence microscopy. The target proteins of IgG and Myo were detected by measuring the conductance change of functionalized single PANI nanowires owing to the capturing of target proteins by mAbs. The detection limit was found to be 3 ng/mL for IgG and 1.4 ng/mL for Myo. No response was observed when single nanowires were exposed to a non-specific protein demonstrating excellent specificity to expected target detection. Together with the fast response time (a few seconds), high sensitivity, and good specificity, this single PANI nanowire-based biosensor shows great promise in the detection of cardiac markers and other proteins. PMID:21269820

  20. Last Advances in Silicon-Based Optical Biosensors

    Science.gov (United States)

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

    2016-01-01

    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. PMID:26927105

  1. 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.

  2. 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)

  3. Multi-diameter silicon nanowires: Fabrication, characterization, and modeling

    Science.gov (United States)

    Alagoz, Arif Sinan

    Nanotechnology is a rapidly expanding interdisciplinary field offering novel devices for broad range of applications. Quantum effects and surface to volume ratio of nanostructures are strongly size dependent, and redefine material properties at nanoscale. Silicon is one of the most promising materials for next generation nanostructured transistors, photonics devices, Li-ion batteries, photovoltaic solar cells, and thermoelectric energy generators. Since electrical, optical, and mechanical properties of nanostructures strongly depend on their shape, size, periodicity, and crystal structure; it is crucial to control these parameters in order to optimize device performance for targeted applications. This dissertation is intended to develop a low-cost, low-temperature, high-throughput, and large-area nanowire fabrication method that can produce well-ordered arrays of hierarchical single-crystal silicon nanowires at large scale by using nanosphere lithography and metal-assisted chemical etching. Nanowire morphology was characterized by using scanning electron microscope and optical properties of nanowire arrays were modeled with the help of finite-difference-time domain method. These novel multi-diameter silicon nanowire arrays have the potential applications in many fields including but not limited to next generation nanowire solar cells to field ionization gas sensors.

  4. 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.

  5. Potentialities of silicon nanowire forests for thermoelectric generation

    Science.gov (United States)

    Dimaggio, Elisabetta; Pennelli, Giovanni

    2018-04-01

    Silicon is a material with very good thermoelectric properties, with regard to Seebeck coefficient and electrical conductivity. Low thermal conductivities, and hence high thermal to electrical conversion efficiencies, can be achieved in nanostructures, which are smaller than the phonon mean free path but large enough to preserve the electrical conductivity. We demonstrate that it is possible to fabricate a leg of a thermoelectric generator based on large collections of long nanowires, placed perpendicularly to the two faces of a silicon wafer. The process exploits the metal assisted etching technique which is simple, low cost, and can be easily applied to large surfaces. Copper can be deposited by electrodeposition on both faces, so that contacts can be provided, on top of the nanowires. Thermal conductivity of silicon nanowire forests with more than 107 nanowires mm-2 have been measured; the result is comparable with that achieved by several groups on devices based on few nanowires. On the basis of the measured parameters, numerical calculations of the efficiency of silicon-based thermoelectric generators are reported, and the potentialities of these devices for thermal to electrical energy conversion are shown. Criteria to improve the conversion efficiency are suggested and described.

  6. Silicon carbide: a versatile material for biosensor applications.

    Science.gov (United States)

    Oliveros, Alexandra; Guiseppi-Elie, Anthony; Saddow, Stephen E

    2013-04-01

    Silicon carbide (SiC) has been around for more than 100 years as an industrial material and has found wide and varied applications because of its unique electrical and thermal properties. In recent years there has been increased attention to SiC as a viable material for biomedical applications. Of particular interest in this review is its potential for application as a biotransducer in biosensors. Among these applications are those where SiC is used as a substrate material, taking advantage of its surface chemical, tribological and electrical properties. In addition, its potential for integration as system on a chip and those applications where SiC is used as an active material make it a suitable substrate for micro-device fabrication. This review highlights the critical properties of SiC for application as a biosensor and reviews recent work reported on using SiC as an active or passive material in biotransducers and biosensors.

  7. 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.

  8. Lithium ion battery peformance of silicon nanowires with carbon skin.

    Science.gov (United States)

    Bogart, Timothy D; Oka, Daichi; Lu, Xiaotang; Gu, Meng; Wang, Chongmin; Korgel, Brian A

    2014-01-28

    Silicon (Si) nanomaterials have emerged as a leading candidate for next generation lithium-ion battery anodes. However, the low electrical conductivity of Si requires the use of conductive additives in the anode film. Here we report a solution-based synthesis of Si nanowires with a conductive carbon skin. Without any conductive additive, the Si nanowire electrodes exhibited capacities of over 2000 mA h g(-1) for 100 cycles when cycled at C/10 and over 1200 mA h g(-1) when cycled more rapidly at 1C against Li metal. In situ transmission electron microscopy (TEM) observation reveals that the carbon skin performs dual roles: it speeds lithiation of the Si nanowires significantly, while also constraining the final volume expansion. The present work sheds light on ways to optimize lithium battery performance by smartly tailoring the nanostructure of composition of materials based on silicon and carbon.

  9. 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.

  10. 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

  11. H2 sensing properties of modified silicon nanowires

    Directory of Open Access Journals (Sweden)

    Latefa Baba Ahmed

    2015-04-01

    Full Text Available It has been found that the silicon nanowires modified with noble metals can be used to fabricate an effective H2 gas sensor in the present study. The preparation and surface modification of silicon nanowires (SiNWs were carried out by chemical methods. The morphology of the silicon nanowires unmodified and modified with nanoparticles of platinum, palladium, silver and gold was investigated using scanning electron microscopy (SEM. The chemical composition of the silicon nanowire layers was studied by secondary ion mass spectroscopy (SIMS and energy dispersive X-ray analysis (EDX. The structures of type metal/SiNWs/p-Si/Al were fabricated. The electrical characterization (I–V was performed in primary vacuum and H2 at different concentrations. It was found that the metal type used to modify the SiNWs strongly influenced the I–V characteristics. The response of these structures toward H2 gas was studied as a function of the metal type. Finally, the sensing characteristics and performance of the sensors were investigated.

  12. Silicon nanowire device and method for its manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat; Draper, Bruce L.; Resnick, Paul J.

    2017-01-03

    There is provided an electronic device and a method for its manufacture. The device comprises an elongate silicon nanowire less than 0.5 .mu.m in cross-sectional dimensions and having a hexagonal cross-sectional shape due to annealing-induced energy relaxation.

  13. Surface functionalization of HF-treated silicon nanowires

    Indian Academy of Sciences (India)

    Administrator

    well as applications. One of the special interests of SiNWs is that their surfaces can be easily modified to act as both elec- ... functionalized the SiNWs via nanoscale Joule heat- ing. 23. Shir et al investigated the oxidation of silicon nanowires. 24 .... cording to Vegard's law. 29. Figure 5b presents a TEM image of one single.

  14. 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.

  15. Effect of eccentricity on junction and junctionless based silicon nanowire and silicon nanotube FETs

    Science.gov (United States)

    Scarlet, S. Priscilla; Ambika, R.; Srinivasan, R.

    2017-07-01

    In this paper, the effect of eccentricity on Junction-based Silicon Nanowire FET, Junction-based Silicon Nanotube FET, Junctionless-based Silicon Nanowire FET, and Junctionless-based Silicon Nanotube FET is investigated. Three kinds of eccentric structures are considered here. The impact of eccentricity on effective gate oxide thickness thereby gate oxide capacitance, and effective channel width are studied using 3D numerical simulations. Average radius of an ellipse is used to generate a model which captures the impact of eccentricity on gate oxide capacitance, and verified using TCAD simulations in MOS nanowire structure. The impact of eccentricity on ON current (ION), OFF current (IOFF), ION/IOFF ratio, and Unity gain cutoff frequency are investigated. Eccentricity increases the effective gate oxide thickness, the effective channel width, ION, and IOFF but reduces ION/IOFF ratio.

  16. Reconfigurable quadruple quantum dots in a silicon nanowire transistor

    Energy Technology Data Exchange (ETDEWEB)

    Betz, A. C., E-mail: ab2106@cam.ac.uk; Broström, M.; Gonzalez-Zalba, M. F. [Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Tagliaferri, M. L. V. [Laboratorio MDM, CNR-IMM, Via C. Olivetti 2, 20864 Agrate Brianza (MB) (Italy); Dipartimento di Scienza dei Materiali, Universit di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Vinet, M. [CEA/LETI-MINATEC, CEA-Grenoble, 17 rue des martyrs, F-38054 Grenoble (France); Sanquer, M. [SPSMS, UMR-E CEA/UJF-Grenoble 1, INAC, 17 rue des Martyrs, 38054 Grenoble (France); Ferguson, A. J. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)

    2016-05-16

    We present a reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consists of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired with improved silicon fabrication techniques, makes the corner state quantum dot approach a promising candidate for a scalable quantum information architecture.

  17. Reconfigurable quadruple quantum dots in a silicon nanowire transistor

    International Nuclear Information System (INIS)

    Betz, A. C.; Broström, M.; Gonzalez-Zalba, M. F.; Tagliaferri, M. L. V.; Vinet, M.; Sanquer, M.; Ferguson, A. J.

    2016-01-01

    We present a reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consists of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired with improved silicon fabrication techniques, makes the corner state quantum dot approach a promising candidate for a scalable quantum information architecture.

  18. Advances in nanowire bioelectronics

    Science.gov (United States)

    Zhou, Wei; Dai, Xiaochuan; Lieber, Charles M.

    2017-01-01

    Semiconductor nanowires represent powerful building blocks for next generation bioelectronics given their attractive properties, including nanometer-scale footprint comparable to subcellular structures and bio-molecules, configurable in nonstandard device geometries readily interfaced with biological systems, high surface-to-volume ratios, fast signal responses, and minimum consumption of energy. In this review article, we summarize recent progress in the field of nanowire bioelectronics with a focus primarily on silicon nanowire field-effect transistor biosensors. First, the synthesis and assembly of semiconductor nanowires will be described, including the basics of nanowire FETs crucial to their configuration as biosensors. Second, we will introduce and review recent results in nanowire bioelectronics for biomedical applications ranging from label-free sensing of biomolecules, to extracellular and intracellular electrophysiological recording.

  19. 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

  20. 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.

  1. 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

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

    Science.gov (United States)

    2016-08-19

    film is controlled so that after subsequent oxidation, a gap of Figure 2. Key steps in the fabrication of silicon field emitter arrays (FEAs) with...Nanofabrication of arrays of silicon field emitters with vertical silicon nanowire current limiters and self-aligned gates S A Guerrera and A I...Published 13 June 2016 Abstract We developed a fabrication process for embedding a dense array (108 cm−2) of high-aspect-ratio silicon nanowires (200 nm

  3. 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.

  4. Translating silicon nanowire BioFET sensor-technology to embedded point-of-care medical diagnostics

    DEFF Research Database (Denmark)

    Pfreundt, Andrea; Zulfiqar, Azeem; Patou, François

    2013-01-01

    Silicon nanowire and nanoribbon biosensors have shown great promise in the detection of biomarkers at very low concentrations. Their high sensitivity makes them ideal candidates for use in early-stage medical diagnostics and further disease monitoring where low amounts of biomarkers need to be de......Silicon nanowire and nanoribbon biosensors have shown great promise in the detection of biomarkers at very low concentrations. Their high sensitivity makes them ideal candidates for use in early-stage medical diagnostics and further disease monitoring where low amounts of biomarkers need...... to be detected. However, in order to translate this technology from the bench to the bedside, a number of key issues need to be taken into consideration: Integrating nanobiosensors-based technology requires to overcome the difficult tradeoff between imperatives for high device reproducibilty and associated......, which require a specific set of biomakers to be identified and quantified simultaneously, can thus be readily translated onto this platform. After hydrogen termination of the silicon surface an alkyne monolayer is formed based on a hydrosilylation process. Antibodies and other receptor proteins can...

  5. 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.

  6. 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.

  7. 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)

  8. Low temperature phonon boundary scattering in slightly rough Silicon nanowires

    Science.gov (United States)

    Ghossoub, Marc; Valavala, Krishna; Seong, Myunghoon; Azeredo, Bruno; Sadhu, Jyothi S.; Sinha, Sanjiv

    2013-03-01

    Nanostructured materials have lower thermal conductivities than the bulk and are promising candidates for thermoelectric applications. In particular, measurements on single silicon nanowires show a reduction in thermal conductivity below the Casimir limit. This reduction increases with surface roughness but the trend and its connection to phonon boundary scattering are still elusive. Here, we measure the thermal conductivity of single silicon nanowires fabricated using metal-assisted chemical etching. High resolution TEM imaging shows crystalline wires with slightly rough surfaces. Their statistical correlation lengths (5-15 nm) and RMS heights (0.8-1.5 nm) are in a range where perturbation-based wave scattering theory is still applicable. We use the thermal conductivity data to extract the frequency dependence of phonon boundary scattering at low temperatures (10-40 K) and show agreement with multiple scattering theory. This work provides insight into enhancing the thermoelectric performance of nanostructures.

  9. Funnel-shaped silicon nanowire for highly efficient light trapping.

    Science.gov (United States)

    Hussein, Mohamed; Hameed, Mohamed Farhat O; Areed, Nihal F F; Yahia, Ashraf; Obayya, S S A

    2016-03-01

    In this Letter, funnel-shaped silicon nanowires (SiNWs) are newly introduced for highly efficient light trapping. The proposed designs of nanowires are inspired by the funnel shape, which enhances the light trapping with reduced reflections in the wavelength range from 300 to 1100 nm. Composed of both cylindrical and conical units, the funnel nanowires increase the number of leaky mode resonances, yielding an absorption enhancement relative to a uniform nanowire array. The optical properties of the suggested nanowires have been numerically investigated using the 3D finite difference time domain (FDTD) method and compared to cylindrical and conical counterparts. The structural geometrical parameters are studied to maximize the ultimate efficiency and hence the short-circuit current. Carefully engineered structure geometry is shown to yield improved light absorption useful for solar cell applications. The proposed funnel-shaped SiNWs offer an ultimate efficiency of 41.8%, with an enhancement of 54.8% relative to conventional cylindrical SiNWs. Additionally, short-circuit current of 34.2  mA/cm2 is achieved using the suggested design.

  10. 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.

  11. Graphene/silicon nanowire Schottky junction for enhanced light harvesting.

    Science.gov (United States)

    Fan, Guifeng; Zhu, Hongwei; Wang, Kunlin; Wei, Jinquan; Li, Xinming; Shu, Qinke; Guo, Ning; Wu, Dehai

    2011-03-01

    Schottky junction solar cells are assembled by directly coating graphene films on n-type silicon nanowire (SiNW) arrays. The graphene/SiNW junction shows enhanced light trapping and faster carrier transport compared to the graphene/planar Si structure. With chemical doping, the SiNW-based solar cells showed energy conversion efficiencies of up to 2.86% at AM1.5 condition, opening a possibility of using graphene/semiconductor nanostructures in photovoltaic application.

  12. Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires

    OpenAIRE

    Yang, Nuo; Zhang, Gang; Li, Baowen

    2007-01-01

    The thermal conductivity of silicon nanowires (SiNWs) is investigated by molecular dynamics (MD) simulation. It is found that the thermal conductivity of SiNWs can be reduced exponentially by isotopic defects at room temperature. The thermal conductivity reaches the minimum, which is about 27% of that of pure 28Si NW, when doped with fifty percent isotope atoms. The thermal conductivity of isotopic-superlattice structured SiNWs depends clearly on the period of superlattice. At a critical peri...

  13. Enhanced thermoelectric performance of rough silicon nanowires

    Science.gov (United States)

    Hochbaum, Allon I.; Chen, Renkun; Delgado, Raul Diaz; Liang, Wenjie; Garnett, Erik C.; Najarian, Mark; Majumdar, Arun; Yang, Peidong

    2008-01-01

    Approximately 90 per cent of the world's power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30-40 per cent efficiency, such that roughly 15terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components, which is a function of the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature. Over the past five decades it has been challenging to increase ZT>1, since the parameters of ZT are generally interdependent. While nanostructured thermoelectric materials can increase ZT>1 (refs 2-4), the materials (Bi, Te, Pb, Sb, and Ag) and processes used are not often easy to scale to practically useful dimensions. Here we report the electrochemical synthesis of large-area, wafer-scale arrays of rough Si nanowires that are 20-300nm in diameter. These nanowires have Seebeck coefficient and electrical resistivity values that are the same as doped bulk Si, but those with diameters of about 50nm exhibit 100-fold reduction in thermal conductivity, yielding ZT = 0.6 at room temperature. For such nanowires, the lattice contribution to thermal conductivity approaches the amorphous limit for Si, which cannot be explained by current theories. Although bulk Si is a poor thermoelectric material, by greatly reducing thermal conductivity without much affecting the Seebeck coefficient and electrical resistivity, Si nanowire arrays show promise as high-performance, scalable thermoelectric materials.

  14. Electronic Structure of Silicon Nanowires Matrix from Ab Initio Calculations.

    Science.gov (United States)

    Monastyrskii, Liubomyr S; Boyko, Yaroslav V; Sokolovskii, Bogdan S; Potashnyk, Vasylyna Ya

    2016-12-01

    An investigation of the model of porous silicon in the form of periodic set of silicon nanowires has been carried out. The electronic energy structure was studied using a first-principle band method-the method of pseudopotentials (ultrasoft potentials in the basis of plane waves) and linearized mode of the method of combined pseudopotentials. Due to the use of hybrid exchange-correlation potentials (B3LYP), the quantitative agreement of the calculated value of band gap in the bulk material with experimental data is achieved. The obtained results show that passivation of dangling bonds with hydrogen atoms leads to substantial transformation of electronic energy structure. At complete passivation of the dangling silicon bonds by hydrogen atoms, the band gap value takes the magnitude which substantially exceeds that for bulk silicon. The incomplete passivation gives rise to opposite effect when the band gap value decreases down the semimetallic range.

  15. 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.

  16. Expanding the versatility of silicon carbide thin films and nanowires

    Science.gov (United States)

    Luna, Lunet

    Silicon carbide (SiC) based electronics and sensors hold promise for pushing past the limits of current technology to achieve small, durable devices that can function in high-temperature, high-voltage, corrosive, and biological environments. SiC is an ideal material for such conditions due to its high mechanical strength, excellent chemical stability, and its biocompatibility. Consequently, SiC thin films and nanowires have attracted interest in applications such as micro- and nano-electromechanical systems, biological sensors, field emission cathodes, and energy storage devices. However to fully realize SiC in such technologies, the reliability of metal contacts to SiC at high temperatures must be improved and the nanowire growth mechanism must be understood to enable strict control of nanowire crystal structure and orientation. Here, we present a novel metallization scheme, utilizing solid-state graphitization of SiC, to improve the long-term reliability of Pt/Ti contacts to polycrystalline n-type SiC films at high temperature. The metallization scheme includes an alumina protection layer and exhibits low, stable contact resistivity even after long-term (500 hr) testing in air at 450 ºC. We also report the crystal structure and growth mechanism of Ni-assisted silicon carbide nanowires using single-source precursor, methyltrichlorosilane. The effects of growth parameters, such as substrate and temperature, on the structure and morphology of the resulting nanowires will also be presented. Overall, this study provides new insights towards the realization of novel SiC technologies, enabled by advanced electron microscopy techniques located in the user facilities at the Molecular Foundry in Berkeley, California. This work was performed in part at the Molecular Foundry, supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  17. 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.

  18. Insights into gold-catalyzed plasma-assisted CVD growth of silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wanghua, E-mail: wanghua.chen@polytechnique.edu; Roca i Cabarrocas, Pere [LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France)

    2016-07-25

    Understanding and controlling effectively the behavior of metal catalyst droplets during the Vapor-Liquid-Solid growth of nanowires are crucial for their applications. In this work, silicon nanowires are produced by plasma-assisted Chemical Vapor Deposition using gold as a catalyst. The influence of hydrogen plasma on nanowire growth is investigated experimentally and theoretically. Interestingly, in contrast to conventional chemical vapor deposition, the growth rate of silicon nanowires shows a decrease as a function of their diameters, which is consistent with the incorporation of silicon via sidewall diffusion. We show that Ostwald ripening of catalyst droplets during nanowire growth is inhibited in the presence of a hydrogen plasma. However, when the plasma is off, the diffusion of Au atoms on the nanowire sidewall can take place. Based on this observation, we have developed a convenient method to grow silicon nanotrees.

  19. 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.

  20. 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....

  1. 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 s...

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

    OpenAIRE

    Anandan, P.; Malathi, N.; Mohankumar, N.

    2014-01-01

    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 resi...

  3. Structurally controlled deposition of silicon onto nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weijie; Liu, Zuqin; Han, Song; Bornstein, Jonathan; Stefan, Constantin Ionel

    2018-03-20

    Provided herein are nanostructures for lithium ion battery electrodes and methods of fabrication. In some embodiments, a nanostructure template coated with a silicon coating is provided. The silicon coating may include a non-conformal, more porous layer and a conformal, denser layer on the non-conformal, more porous layer. In some embodiments, two different deposition processes, e.g., a PECVD layer to deposit the non-conformal layer and a thermal CVD process to deposit the conformal layer, are used. Anodes including the nanostructures have longer cycle lifetimes than anodes made using either a PECVD or thermal CVD method alone.

  4. Silicon Nanowires for All-Optical Signal Processing in Optical Communication

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2012-01-01

    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......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...... 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...

  5. Interdigitated design of a thermoelectric microgenerator based on silicon nanowire arrays

    Science.gov (United States)

    Donmez, I.; Salleras, M.; Calaza, C.; Santos, J. D.; Gadea, G.; Morata, A.; Dávila, D.; Tarancón, A.; Fonseca, L.

    2015-05-01

    Silicon nanowires thermoelectric properties are much better than those of silicon bulk. Taking advantage of silicon microfabrication techniques and compatibilizing the device fabrication with the CVD-VLS silicon nanowire growth, we present a thermoelectric microgenerator based on silicon nanowire arrays with interdigitated structures which enhance the power density compared to previous designs presented by the authors. The proposed design features a thermally isolated silicon platform on the silicon device layer of an SOI silicon wafer. This silicon platform has vertical walls exposing thermoelectric generator is unileg, which means that only one type of semiconductor is used, and the second connection is made through a metal. In addition, to improve the thermal isolation of the silicon platform, multiple trenches of silicon nanowire arrays are used, up to a maximum of nine. After packaging the device with nanowires, we are able to measure the Seebeck voltage and the power obtained with different operation modes: harvesting mode, where the bottom device is heated up, and the silicon platform is cooled down by natural or forced convection, and test mode, where a heater integrated on the silicon platform is used to produce a thermal gradient.

  6. Monolithically Integrated High-β Nanowire Lasers on Silicon.

    Science.gov (United States)

    Mayer, B; Janker, L; Loitsch, B; Treu, J; Kostenbader, T; Lichtmannecker, S; Reichert, T; Morkötter, S; Kaniber, M; Abstreiter, G; Gies, C; Koblmüller, G; Finley, J J

    2016-01-13

    Reliable technologies for the monolithic integration of lasers onto silicon represent the holy grail for chip-level optical interconnects. In this context, nanowires (NWs) fabricated using III-V semiconductors are of strong interest since they can be grown site-selectively on silicon using conventional epitaxial approaches. Their unique one-dimensional structure and high refractive index naturally facilitate low loss optical waveguiding and optical recirculation in the active NW-core region. However, lasing from NWs on silicon has not been achieved to date, due to the poor modal reflectivity at the NW-silicon interface. We demonstrate how, by inserting a tailored dielectric interlayer at the NW-Si interface, low-threshold single mode lasing can be achieved in vertical-cavity GaAs-AlGaAs core-shell NW lasers on silicon as measured at low temperature. By exploring the output characteristics along a detection direction parallel to the NW-axis, we measure very high spontaneous emission factors comparable to nanocavity lasers (β = 0.2) and achieve ultralow threshold pump energies ≤11 pJ/pulse. Analysis of the input-output characteristics of the NW lasers and the power dependence of the lasing emission line width demonstrate the potential for high pulsation rates ≥250 GHz. Such highly efficient nanolasers grown monolithically on silicon are highly promising for the realization of chip-level optical interconnects.

  7. 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.

  8. A simple and controlled single electron transistor based on doping modulation in silicon nanowires

    OpenAIRE

    Hofheinz, M.; Jehl, X.; Sanquer, M.; Molas, G.; Vinet, M.; Deleonibus, S.

    2006-01-01

    A simple and highly reproducible single electron transistor (SET) has been fabricated using gated silicon nanowires. The structure is a metal-oxide-semiconductor field-effect transistor made on silicon-on-insulator thin films. The channel of the transistor is the Coulomb island at low temperature. Two silicon nitride spacers deposited on each side of the gate create a modulation of doping along the nanowire that creates tunnel barriers. Such barriers are fixed and controlled, like in metallic...

  9. 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.

  10. 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.

  11. A Complex of the Electromagnetic Biosensors with a Nanowired Pickup

    Directory of Open Access Journals (Sweden)

    Rostyslav Sklyar

    2009-01-01

    Full Text Available The proposal to measure the biosignal values of different origins with advanced nanosensors of electromagnetic quantities is justified when allowing for superconducting abilities of the devices. They are composed in full-scale arrays. The said arrays can be both implantable into ionic channels of an organism and sheathed on the sources of the electromagnetic emanation. Nanowired head sensors function both in passive mode for picking up the biosignals and with additional excitation of a defined biomedium through the same head (in reverse. The designed variety of bio-nanosensors allow interfacing a variety of biosignals with the external systems, also with a possibility to control the exposure on an organism by artificially created signals. The calculated signals lies in the range of −5 to 5 V, (7÷0⋅1017/cm3 molecules or magnetic beads, 2÷10 pH, and stream speed 3⋅10−3÷102 m/s, flow 10−5÷10 m/s, and haemoglobin concentration of 1030÷1024 molec/cm3. The sensitivity of this micro- or nanoscope can be estimated as =10−4 (A⋅m/√Hz with SNR equal to 104. The sensitivity of an advanced first-order biogradiometer is equal to 3 fT/√Hz. The smallest resolvable change in magnetic moment detected by this system in the band 10 Hz is 1 fJ/T.

  12. In situ growth of silicon carbide nanowires from anthracite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Fox, J.T.; Cannon, F.S.; Komarneni, S. [Penn State University, University Park, PA (United States)

    2011-04-15

    Silicon carbide nanowires (SCNWs) were grown from anthracite fine surfaces through a simple one-step carbothermal process with silicon powder as the Si precursor. This straightforward and fast formation of SCNWs made it possible to maintain the binding of briquetted waste anthracite fines at very high temperatures as an alternative fuel in foundry cupola furnaces. This SCNW mechanism could thus provide the crucial hot crushing strength in the cupola heat zone and melt zone. Progressive thermal tests exhibited that the formation of the SCNWs started from 1100{sup o}C, and was favored at 1400{sup o}C. No extra metal catalyst was needed for the growth of the SCNWs. Characterizations were performed by XRD, SEM, EDS, TEM, and SAED. The SCNWs were 30-60 nm in diameter. Many non-epitaxial branches of the nanowires were also formed through this one-step process as observed by TEM. The results suggest that the SCNWs were most likely grown through the vapor solid mechanism.

  13. The nature of photocatalytic "water splitting" on silicon nanowires.

    Science.gov (United States)

    Liu, Dong; Li, Leilei; Gao, Yang; Wang, Chengming; Jiang, Jun; Xiong, Yujie

    2015-03-02

    Silicon should be an ideal semiconductor material if it can be proven usable for photocatalytic water splitting, given its high natural abundance. Thus it is imperative to explore the possibility of water splitting by running photocatalysis on a silicon surface and to decode the mechanism behind it. It is reported that hydrogen gas can indeed be produced from Si nanowires when illuminated in water, but the reactions are not a real water-splitting process. Instead, the production of hydrogen gas on the Si nanowires occurs through the cleavage of Si-H bonds and the formation of Si-OH bonds, resulting in the low probability of generating oxygen. On the other hand, these two types of surface dangling bonds both extract photoexcited electrons, whose competition greatly impacts on carrier lifetime and reaction efficiency. Thus surface chemistry holds the key to achieving high efficiency in such a photocatalytic system. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Incubation behavior of silicon nanowire growth investigated by laser-assisted rapid heating

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Sang-gil; Kim, Eunpa; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu [Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Allen, Frances I.; Minor, Andrew M. [Department of Materials Science and Engineering, University of California, Berkeley, California 94720-1740 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hwang, David J. [Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-08-15

    We investigate the early stage of silicon nanowire growth by the vapor-liquid-solid mechanism using laser-localized heating combined with ex-situ chemical mapping analysis by energy-filtered transmission electron microscopy. By achieving fast heating and cooling times, we can precisely determine the nucleation times for nanowire growth. We find that the silicon nanowire nucleation process occurs on a time scale of ∼10 ms, i.e., orders of magnitude faster than the times reported in investigations using furnace processes. The rate-limiting step for silicon nanowire growth at temperatures in the vicinity of the eutectic temperature is found to be the gas reaction and/or the silicon crystal growth process, whereas at higher temperatures it is the rate of silicon diffusion through the molten catalyst that dictates the nucleation kinetics.

  15. 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.

  16. Silicon nanowire formed via shallow anisotropic etching Si-ash-trimming for specific DNA and electrochemical detection

    International Nuclear Information System (INIS)

    Tijjani, Adam; Hashim, U.; Dhahi, Th S.

    2015-01-01

    A functionalized silicon nanowire field-effect transistor (SiNW FET) was fabricated to detect single molecules in the pM range to detect disease at the early stage with a sensitive, robust, and inexpensive method with the ability to provide specific and reliable data. The device was designed and fabricated by indented ash trimming via shallow anisotropic etching. The approach is a simple and low-cost technique that is compatible with the current commercial semiconductor standard CMOS process without an expensive deep reactive ion etcher. Specific electric changes were observed for DNA sensing when the nanowire surface was modified with a complementary captured DNA probe and target DNA through an organic linker (–OCH2CH3) using organofunctional alkoxysilanes (3-aminopropyl) triethoxysilane (APTES). With this surface modification, a single specific target molecule can be detected. The simplicity of the sensing domain makes it feasible to miniaturize it for the development of a cancer detection kit, facilitating its use in both clinical and non-clinical environments to allow non-expert interpretation. With its novel electric response and potential for mass commercial fabrication, this biosensor can be developed to become a portable/point of care biosensor for both field and diagnostic applications. (paper)

  17. 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.

  18. Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ben Dkhil, S., E-mail: sadok.bendekhil@gmail.com [Laboratoire Physique des Materiaux, Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Ingenierie des Materiaux Polymeres, IMP, UMR CNRS 5223, Universite Claude Bernard - Lyon 1, 15, boulevard Latarjet, 69622 Villeurbanne (France); Bourguiga, R. [Laboratoire Physique des Materiaux, Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Davenas, J. [Ingenierie des Materiaux Polymeres, IMP, UMR CNRS 5223, Universite Claude Bernard - Lyon 1, 15, boulevard Latarjet, 69622 Villeurbanne (France); Cornu, D. [Institut Europeen des Membranes, UMR CNRS 5635, Ecole Nationale superieure de Chimie, Universite de Montpellier, 1919 route de Mende, F34000 Montpellier (France)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. Black-Right-Pointing-Pointer We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. Black-Right-Pointing-Pointer The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. Black-Right-Pointing-Pointer 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{sub oc} and short-circuit current density J{sub 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.

  19. 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.

  20. Vertical Silicon Nanowire Diode with Nickel Silicide Induced Dopant Segregation

    Science.gov (United States)

    Lu, Weijie; Pey, Kin Leong; Wang, Xinpeng; Li, Xiang; Chen, Zhixian; Navab, Singh; Chew Leong, Kam; Lip Gan, Chee; Tan, Chuan Seng

    2012-11-01

    Dopant segregated Schottky barrier (DSSB) and Schottky barrier (SB) vertical silicon nanowire (VSiNW) diodes were fabricated using industry complemetary metal oxide semiconductor field effect transistor (CMOS) processes to investigate the effects of segregated dopants at the silicide/silicon interface and different annealing steps on nickel silicide formation in the DSSB VSiNW diodes. With segregated dopants at the silicide/silicon interface, VSiNW diodes showed higher on-current, due to an enhanced carrier tunneling, and much lower off-current. This can be attributed to the altered energy bands caused by the accumulated Arsenic dopants at the interface. Moreover, DSSB VSiNW diodes also presented ideality factor much closer to unity and exhibited lower electron Schottky barrier height (ΦBn) than SB VSiNW diodes. This proved that interfacial accumulated dopants could impede the inhomogeneous nature of the Schottky diodes and simultaneously, minimize the effect of Fermi level pinning and ionization of surface defect states. Comparing the impact of different silicide formation annealing sequence using DSSB VSiNW diodes, the 2-step anneal process reduces the silicide intrusion length within the SiNW by ˜5× and the silicide interface was smooth along the (100) direction. Furthermore, the 2-step DSSB VSiNW diode also exhibited much lower leakage current and an ideality factor much closer to unity, as compared to the 1-step DSSB VSiNW diode.

  1. Ultra-High-Speed Optical Serial-to-Parallel Data Conversion in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Hu, Hao

    2011-01-01

    We demonstrate conversion from 64×10 Gbit/s OTDM to 25 GHz DWDM by time-domain optical Fourier transformation. Using a single silicon nanowire, 40 of 64 OTDM tributaries are simultaneously converted to DWDM channels within FEC limits.......We demonstrate conversion from 64×10 Gbit/s OTDM to 25 GHz DWDM by time-domain optical Fourier transformation. Using a single silicon nanowire, 40 of 64 OTDM tributaries are simultaneously converted to DWDM channels within FEC limits....

  2. 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....

  3. 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....

  4. Nanoscale contact engineering for Silicon/Silicide nanowire devices

    Science.gov (United States)

    Lin, Yung-Chen

    Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at nanoscale have indicated possible deviations from the bulk and the thin film system. Here we studied growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction. We have grown single crystal PtSi nanowires and PtSi/Si/PtSi nanowire heterostructures through solid state reaction. TEM studies show that the heterostructures have atomically sharp interfaces free of defects. Electrical measurement of PtSi nanowires shows a low resistivity of ˜28.6 μΩ·cm and a high breakdown current density beyond 108 A/cm2. Furthermore, using single-crystal PtSi/Si/PtSi nanowire heterostructures with atomically clean interfaces, we have fabricated p-channel enhancement mode transistors with the best reported performance for intrinsic silicon nanowires to date. In our results, silicide can provide a clean and no Fermi level pinning interface and then silicide can form Ohmic-contact behavior by replacing the source/drain metal with PtSi. It has been proven by our experiment by contacting PtSi with intrinsic Si nanowires (no extrinsic doping) to achieve high performance p-channel device. By utilizing the same approach, single crystal MnSi nanowires and MnSi/Si/MnSi nanowire heterojunction with atomically sharp interfaces can also been grown. Electrical transport studies on Mn

  5. 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.

  6. Transport in Silicon Nanowires: Role of Radial Dopant Profile

    DEFF Research Database (Denmark)

    Markussen, Troels; Rurali, Riccardo; Jauho, Antti-Pekka

    2008-01-01

    We consider the electronic transport properties of phosphorus (P) doped silicon nanowires (SiNWs). By combining ab initio density functional theory (DFT) calculations with a recursive Green's function method, we calculate the conductance distribution of up to 200 nm long SiNWs with different...... distributions of P dopant impurities. We find that the radial distribution of the dopants influences the conductance properties significantly: surface doped wires have longer mean-free paths and smaller sample-to-sample fluctuations in the cross-over from ballistic to diffusive transport. These findings can...... be quantitatively predicted in terms of the scattering properties of the single dopant atoms, implying that relatively simple calculations are sufficient in practical device modeling....

  7. 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).

  8. 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.

  9. Synthesis and Characterization of Silicon Nanowires by Electroless Etching

    Science.gov (United States)

    Bhujel, Rabina; Rizal, Umesh; Agarwal, Amit; Swain, Bhabani S.; Swain, Bibhu P.

    2018-02-01

    Silicon nanowires (SiNWs) were synthesized by two-step electroless etching of p-type Si (100) wafer and characterized by field emission scanning electron microscopy, UV-Vis spectroscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The vibrational signature at 1108 and 2087 cm-1 confirmed SiNWs were passivated by both oxygen and hydrogen atoms. Raman peak at 517 cm-1 indicated crystalline SiNWs with tailing toward redshift due to Fano effect. The Si(2p) and Si(2s) core orbital spectra of SiNWs were found at 99.8 and 150.5 eV, respectively. Moreover, the reflection of SiNWs is minimized to 1 to 5% in the 650-nm wavelength.

  10. 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.

  11. 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.

  12. 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.

  13. Specific and reversible immobilization of histidine-tagged proteins on functionalized silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi-Chi C; Rieben, Nathalie; Iversen, Lars; Martinez, Karen L [Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Oe (Denmark); Soerensen, Brian S; Nygaard, Jesper [Niels Bohr Institute and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Oe (Denmark); Park, Jiwoong, E-mail: martinez@nano.ku.dk [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 (United States)

    2010-06-18

    Silicon nanowire (Si NW)-based field effect transistors (FETs) have shown great potential as biosensors (bioFETs) for ultra-sensitive and label-free detection of biomolecular interactions. Their sensitivity depends not only on the device properties, but also on the function of the biological recognition motif attached to the Si NWs. In this study, we show that SiNWs can be chemically functionalized with Ni:NTA motifs, suitable for the specific immobilization of proteins via a short polyhistidine tag (His-tag) at close proximity to the SiNW surface. We demonstrate that the proteins preserve their function upon immobilization onto SiNWs. Importantly, the protein immobilization on the Si NWs is shown to be reversible after addition of EDTA or imidazole, thus allowing the regeneration of the bioFET when needed, such as in the case of proteins having a limited lifetime. We anticipate that our methodology may find a generic use for the development of bioFETs exploiting functional protein assays because of its high compatibility to various types of NWs and proteins.

  14. 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.

  15. 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.

  16. 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.

  17. Intrinsic and doped coupled quantum dots created by local modulation of implantation in a silicon nanowire

    Science.gov (United States)

    Pierre, M.; Roche, B.; Wacquez, R.; Jehl, X.; Sanquer, M.; Vinet, M.

    2011-04-01

    We present a systematic study of various ways (top gates, local doping, substrate bias) to fabricate and tune multi-dot structures in silicon nanowire multigate metal-oxide-semiconductor field-effect transistors. The carrier concentration profile of the silicon nanowire is a key parameter to control the formation of tunnel barriers and single-electron islands. It is determined both by the doping profile of the nanowire and by the voltages applied to the top gates and to the substrate. Local doping is achieved with the realization of up to two arsenic implantation steps in combination with gates and nitride spacers acting as a mask. We compare nominally identical devices with different implantations and different voltages applied to the substrate, leading to the realization of both intrinsic and doped coupled dot structures. We demonstrate devices in which all the tunnel resistances toward the electrodes and between the dots can be independently tuned with the control top gates wrapping the silicon nanowire.

  18. 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.

  19. Optical back-action in silicon nanowire resonators: bolometric versus radiation pressure effects

    Science.gov (United States)

    Gil-Santos, E.; Ramos, D.; Pini, V.; Llorens, J.; Fernández-Regúlez, M.; Calleja, M.; Tamayo, J.; San Paulo, A.

    2013-03-01

    We study optical back-action effects associated with confined electromagnetic modes in silicon nanowire resonators interacting with a laser beam used for interferometric read-out of the nanowire vibrations. Our analysis describes the resonance frequency shift produced in the nanowires by two different mechanisms: the temperature dependence of the nanowire's Young's modulus and the effect of radiation pressure. We find different regimes in which each effect dominates depending on the nanowire morphology and dimensions, resulting in either positive or negative frequency shifts. Our results also show that in some cases bolometric and radiation pressure effects can have opposite contributions so that their overall effect is greatly reduced. We conclude that Si nanowire resonators can be engineered for harnessing back-action effects for either optimizing frequency stability or exploiting dynamic phenomena such as parametric amplification.

  20. 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

  1. Prelithiated silicon nanowires as an anode for lithium ion batteries.

    Science.gov (United States)

    Liu, Nian; Hu, Liangbing; McDowell, Matthew T; Jackson, Ariel; Cui, Yi

    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

  2. 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.

  3. 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

  4. 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.

  5. Comparative study of absorption in tilted silicon nanowire arrays for photovoltaics.

    Science.gov (United States)

    Kayes, Md Imrul; Leu, Paul W

    2014-01-01

    Silicon nanowire arrays have been shown to demonstrate light trapping properties and promising potential for next-generation photovoltaics. In this paper, we show that the absorption enhancement in vertical nanowire arrays on a perfectly electric conductor can be further improved through tilting. Vertical nanowire arrays have a 66.2% improvement in ultimate efficiency over an ideal double-pass thin film of the equivalent amount of material. Tilted nanowire arrays, with the same amount of material, exhibit improved performance over vertical nanowire arrays across a broad range of tilt angles (from 38° to 72°). The optimum tilt of 53° has an improvement of 8.6% over that of vertical nanowire arrays and 80.4% over that of the ideal double-pass thin film. Tilted nanowire arrays exhibit improved absorption over the solar spectrum compared with vertical nanowires since the tilt allows for the excitation of additional modes besides the HE 1m modes that are excited at normal incidence. We also observed that tilted nanowire arrays have improved performance over vertical nanowire arrays for a large range of incidence angles (under about 60°).

  6. 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...

  7. 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 −14 to 1.0 × 10 −8 M), with a detection limit of 3.5 × 10 −15 M (signal/noise ratio of 3). The biosensor also showed high selectivity to

  8. 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

  9. 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.

  10. Long Wavelength Plasmonic Absorption Enhancement in Silicon Using Optical Lithography Compatible Core-Shell-Type Nanowires

    Directory of Open Access Journals (Sweden)

    Mohammed Shahriar Sabuktagin

    2014-01-01

    Full Text Available Plasmonic properties of rectangular core-shell type nanowires embedded in thin film silicon solar cell structure were characterized using FDTD simulations. Plasmon resonance of these nanowires showed tunability from  nm. However this absorption was significantly smaller than the Ohmic loss in the silver shell due to very low near-bandgap absorption properties of silicon. Prospect of improving enhanced absorption in silicon to Ohmic loss ratio by utilizing dual capability of these nanowires in boosting impurity photovoltaic effect and efficient extraction of the photogenerated carriers was discussed. Our results indicate that high volume fabrication capacity of optical lithography techniques can be utilized for plasmonic absorption enhancement in thin film silicon solar cells over the entire long wavelength range of solar radiation.

  11. 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

  12. 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.

  13. Biosensors.

    Science.gov (United States)

    Rechnitz, Garry A.

    1988-01-01

    Describes theory and principles behind biosensors that incorporate biological components as part of a sensor or probe. Projects major applications in medicine and veterinary medicine, biotechnology, food and agriculture, environmental studies, and the military. Surveys current use of biosensors. (ML)

  14. Interfacial Engineering of Silicon Carbide Nanowire/Cellulose Microcrystal Paper toward High Thermal Conductivity.

    Science.gov (United States)

    Yao, Yimin; Zeng, Xiaoliang; Pan, Guiran; Sun, Jiajia; Hu, Jiantao; Huang, Yun; Sun, Rong; Xu, Jian-Bin; Wong, Ching-Ping

    2016-11-16

    Polymer composites with high thermal conductivity have attracted much attention, along with the rapid development of electronic devices toward higher speed and better performance. However, high interfacial thermal resistance between fillers and matrix or between fillers and fillers has been one of the primary bottlenecks for the effective thermal conduction in polymer composites. Herein, we report on engineering interfacial structure of silicon carbide nanowire/cellulose microcrystal paper by generating silver nanostructures. We show that silver nanoparticle-deposited silicon carbide nanowires as fillers can effectively enhance the thermal conductivity of the matrix. The in-plane thermal conductivity of the resultant composite paper reaches as high as 34.0 W/m K, which is one order magnitude higher than that of conventional polymer composites. Fitting the measured thermal conductivity with theoretical models qualitatively demonstrates that silver nanoparticles bring the lower interfacial thermal resistances both at silicon carbide nanowire/cellulose microcrystal and silicon carbide nanowire/silicon carbide nanowire interfaces. This interfacial engineering approach provides a powerful tool for sophisticated fabrication of high-performance thermal-management materials.

  15. Direct monolithic integration of vertical single crystalline octahedral molecular sieve nanowires on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Carretero-Genevrier, Adrian [Institut des Nanotechnologies de Lyon (INL), UMR-CNRS 5270, Ecole Central de Lyon, Ecully (France); Institut de Ciencia de Materials de Barcelona ICMAB, Catalonia (Spain); Sorbonne Univ., UPMC Univ. Paris 06, CNRS, College de France, Paris (France); Oro-Sole, Judith [Institut de Ciencia de Materials de Barcelona ICMAB, Catalonia (Spain); Gazquez, Jaume [Institut de Ciencia de Materials de Barcelona ICMAB, Catalonia (Spain); Magen, Cesar [Univ. de Zaragoza, Zaragoza (Spain); Miranda, Laura [Sorbonne Univ., UPMC Univ. Paris 06, CNRS, College de France, Paris (France); Puig, Teresa [Institut de Ciencia de Materials de Barcelona ICMAB, Catalonia (Spain); Obradors, Xavier [Institut de Ciencia de Materials de Barcelona ICMAB, Catalonia (Spain); Ferain, Etienne [Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium); Sanchez, Clement [Sorbonne Univ., UPMC Univ. Paris 06, CNRS, College de France, Paris (France); Rodriguez-Carvajal, Juan [Institut Laue-Langevin, Grenoble Cedex (France); Mestres, Narcis [Institut de Ciencia de Materials de Barcelona ICMAB, Catalonia (Spain)

    2013-12-13

    We developed an original strategy to produce vertical epitaxial single crystalline manganese oxide octahedral molecular sieve (OMS) nanowires with tunable pore sizes and compositions on silicon substrates by using a chemical solution deposition approach. The nanowire growth mechanism involves the use of track-etched nanoporous polymer templates combined with the controlled growth of quartz thin films at the silicon surface, which allowed OMS nanowires to stabilize and crystallize. α-quartz thin films were obtained after thermal activated crystallization of the native amorphous silica surface layer assisted by Sr2+- or Ba2+-mediated heterogeneous catalysis in the air at 800 °C. These α-quartz thin films work as a selective template for the epitaxial growth of randomly oriented vertical OMS nanowires. Furthermore, the combination of soft chemistry and epitaxial growth opens new opportunities for the effective integration of novel technological functional tunneled complex oxides nanomaterials on Si substrates.

  16. Numerical investigations into mechanical properties of hexagonal silicon carbon nanowires and nanotubes.

    Science.gov (United States)

    Zheng, Bin; Lowther, John E

    2010-09-01

    Single-crystalline hexagonal faceted silicon carbon nanowires and nanotubes possess simultaneous high strength and failure strain. As long as SiC nanowires or nanotubes are large or thick enough to sustain a single atomic configuration under loading, their mechanical properties are size independent. Surface atoms are firstly forced to move by stretching and then destroy the equilibrium of subsurface atoms. Then, the force in carbon-silicon bonds along the tensile directions becomes larger than that in other bonds and results in elongation by three-times of the former than that of the latter. However, the latter bonds connecting the surface to the subsurface are broken and the wires or tubes are ruptured. For thinner nanowires and nanotubes, the broken bonds don't propagate instantly, but initiate transformation from a wurtzite to a graphitic structure. This structure transformation can strengthen and plasticize SiC nanowires and nanotubes.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.)

  2. Mapping the "forbidden" transverse-optical phonon in single strained silicon (100) nanowire.

    Science.gov (United States)

    Tarun, Alvarado; Hayazawa, Norihiko; Ishitobi, Hidekazu; Kawata, Satoshi; Reiche, Manfred; Moutanabbir, Oussama

    2011-11-09

    The accurate manipulation of strain in silicon nanowires can unveil new fundamental properties and enable novel or enhanced functionalities. To exploit these potentialities, it is essential to overcome major challenges at the fabrication and characterization levels. With this perspective, we have investigated the strain behavior in nanowires fabricated by patterning and etching of 15 nm thick tensile strained silicon (100) membranes. To this end, we have developed a method to excite the "forbidden" transverse-optical (TO) phonons in single tensile strained silicon nanowires using high-resolution polarized Raman spectroscopy. Detecting this phonon is critical for precise analysis of strain in nanoscale systems. The intensity of the measured Raman spectra is analyzed based on three-dimensional field distribution of radial, azimuthal, and linear polarizations focused by a high numerical aperture lens. The effects of sample geometry on the sensitivity of TO measurement are addressed. A significantly higher sensitivity is demonstrated for nanowires as compared to thin layers. In-plane and out-of-plane strain profiles in single nanowires are obtained through the simultaneous probe of local TO and longitudinal-optical (LO) phonons. New insights into strained nanowires mechanical properties are inferred from the measured strain profiles.

  3. 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.

  4. Multichannel nonlinear distortion compensation using optical phase conjugation in a silicon nanowire

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Schoerder, Jochen; Da Ros, Francesco

    2015-01-01

    We experimentally demonstrate compensation of nonlinear distortion caused by the Kerr effect in a 3 x 32-Gbaud quadrature phase-shift keying (QPSK) wavelength-division multiplexing (WDM) transmission system. We use optical phase conjugation (OPC) produced by four-wave mixing (FWM) in a 7-mm long...... silicon nanowire. A clear improvement in Q-factor is shown after 800-km transmission with high span input power when comparing the system with and without the optical phase conjugation module. The influence of OSNR degradation introduced by the silicon nanowire is analysed by comparing transmission...... systems of three different lengths. This is the first demonstration of nonlinear compensation using a silicon nanowire. (C)2015 Optical Society of America...

  5. 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.

  6. Self-Powered Photoelectrochemical Biosensor Based on CdS/RGO/ZnO Nanowire Array Heterostructure.

    Science.gov (United States)

    Zhao, Kun; Yan, Xiaoqin; Gu, Yousong; Kang, Zhuo; Bai, Zhiming; Cao, Shiyao; Liu, Yichong; Zhang, Xiaohui; Zhang, Yue

    2016-01-13

    A CdS/reduced graphene oxide (RGO)/ZnO nanowire array (NWAs) heterostructure is designed, which exhibits enhanced photoelectrochemical (PEC) activity compared to pure ZnO, RGO/ZnO, and CdS/ZnO. The enhancement can be attributed to the synergistic effect of the high electron mobility of ordered 1D ZnO NWAs, extended visible-light absorption of CdS nanocrystals, and the formed type II band alignment between them. Moreover, the incorporation of RGO further promotes the charge carrier separation and transfer process due to its excellent charge collection and shuttling characteristics. Subsequently, the CdS/RGO/ZnO heterostructure is successfully utilized for the PEC bioanalysis of glutathione at 0 V (vs Ag/AgCl). The self-powered device demonstrates satisfactory sensing performance with rapid response, a wide detection range from 0.05 mm to 1 mm, an acceptable detection limit of 10 μm, as well as certain selectivity, reproducibility, and stability. Therefore, the CdS/RGO/ZnO heterostructure has opened up a promising channel for the development of PEC biosensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Glucose biosensor based on functionalized ZnO nanowire/graphite films dispersed on a Pt electrode

    Science.gov (United States)

    Gallay, P.; Tosi, E.; Madrid, R.; Tirado, M.; Comedi, D.

    2016-10-01

    We present a glucose biosensor based on ZnO nanowire self-sustained films grown on compacted graphite flakes by the vapor transport method. Nanowire/graphite films were fragmented in water, filtered to form a colloidal suspension, subsequently functionalized with glucose oxidase and finally transferred to a metal electrode (Pt). The obtained devices were evaluated using scanning electron microscopy, energy-dispersive x-ray spectroscopy, cyclic voltammetry and chronoamperometry. The electrochemical responses of the devices were determined in buffer solutions with successive glucose aggregates using a tripolar electrode system. The nanostructured biosensors showed excellent analytical performance, with linear response to glucose concentrations, high sensitivity of up to ≈17 μA cm-2 mM-1 in the 0.03-1.52 mM glucose concentration range, relatively low Michaelis-Menten constant, excellent reproducibility and a fast response. The detection limits are more than an order of magnitude lower than those achievable in commercial biosensors for glucose control, which is promising for the development of glucose monitoring methods that do not require blood extraction from potentially diabetic patients. The strong detection enhancements provided by the functionalized nanostructures are much larger than the electrode surface-area increase and are discussed in terms of the physical and chemical mechanisms involved in the detection and transduction processes.

  8. Advancing Porous Silicon Biosensor Technology for Use in Clinical Diagnostics

    Science.gov (United States)

    Bonanno, Lisa Marie

    Inexpensive and robust analytical techniques for detecting molecular recognition events are in great demand in healthcare, food safety, and environmental monitoring. Despite vast research in this area, challanges remain to develop practical biomolecular platforms that, meet the rigorous demands of real-world applications. This includes maintaining low-cost devices that are sensitive and specific in complex test specimens, are stable after storage, have short assay time, and possess minimal complexity of instrumentation for readout. Nanostructured porous silicon (PSi) material has been identified as an ideal candidate towards achieving these goals and the past decade has seen diverse proof-of-principle studies developing optical-based sensing techniques. In Part 1 of this thesis, the impact of surface chemistry and PSi morphology on detection sensitivity of target molecules is investigated. Initial proof-of-concept that PSi devices facilitate detection of protein in whole blood is demonstrated. This work highlights the importance of material stability and blocking chemistry for sensor use in real world biological samples. In addition, the intrinisic filtering capability of the 3-D PSi morphology is shown as an advantage in complex solutions, such as whole blood. Ultimately, this initial work identified a need to improve detection sensitivity of the PSI biosensor technique to facilitate clinical diagnostic use over relevant target concentration ranges. The second part of this thesis, builds upon sensitivity challenges that are highlighted in the first part of the thesis and development of a surface-bound competitive inhibition immunoassay facilitated improved detection sensitivity of small molecular weight targets (opiates) over a relevant clinical concentration range. In addition, optimization of assay protocol addressed issues of maintaining stability of sensors after storage. Performance of the developed assay (specificity and sensitivity) was then validated in a

  9. Well incorporation of carbon nanodots with silicon nanowire arrays featuring excellent photocatalytic performances.

    Science.gov (United States)

    Chen, Chia-Yun; Hsiao, Po-Hsuan; Wei, Ta-Cheng; Chen, Ting-Chen; Tang, Chien-Hsin

    2017-05-17

    Recently, silicon (Si) nanowires have been intensively applied for a wide range of optoelectronic applications. Nevertheless, rare explorations considering the photodegradation of organic pollutants based on Si nanowires were performed, and they still require vast improvement, in particular for their degradation efficiency. In this study, broad-band and high efficiency photocatalytic systems were demonstrated through the good incorporation of Si nanowires with highly fluorescent carbon nanodots. The photodegradation rate of these intriguing heterostructure arrays under a 580 nm light illumination is approximately 6 times higher than that of sole Si nanowires, and more than 3.6 and 4.5 times higher than that of Si nanowire incorporated with silver and gold nanoparticles, respectively. Optimizing the luminescent behaviors of carbon nanodots leads to the involvement of multiple light sources that activate the photoexcitation of carriers within the Si nanowires. This feature was further elucidated by examining the corresponding photocurrents under light illumination, which presents currents 1.9 times higher than those with the sole Si nanowires. In combination with excellent wettability with dye solutions, the present heterostructured nanowire arrays have promised the robust photocatalytic capability with retained efficiency after cycling uses, which may open up unique opportunities for future pollutant detoxification and wastewater treatment.

  10. 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.

  11. 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

  12. Hybrid Solar Cells Based on Silicon Nanowire Arrays for Remote Chemical Sensing

    Directory of Open Access Journals (Sweden)

    Joël DAVENAS

    2014-05-01

    Full Text Available Disordered arrays of silicon nanowires have been produced by the OAG technique. The UV-visible absorption spectrum of the SiNWs shows a main increase of the absorption extending in the near infrared and similar absorption than bulk crystalline silicon below 400 nm. T EMT simulation of the UV absorption of silicon nanowires predicts a main optical absorption for a nanowire orientation parallel to the electric field vector of the incident light, as expected for SiNW lying with a dominant orientation parallel to the substrate. The enhanced optical absorption tail extending above 400 nm has been attributed to the combination of band gap opening shown by the PL emission and high densities of silicon surface states at high surface/volume ratio. Hybrid solar cells have been fabricated through the dispersion of silicon nanowires in a poly(3-hexylthiophene thin film leading to a 1.14 % conversion yield, which was increased to 3.04 % upon SiNW surface functionalization, opening new perspectives for self sufficient power supplies applicable to remote sensing.

  13. Electrical characteristics of funnel-shaped silicon nanowire solar cells

    Science.gov (United States)

    Abdel-Latif, Ghada Yassin; Hameed, Mohamed Farhat O.; Hussein, Mohamed; Razzak, Maher Abdel; Obayya, Salah S. A.

    2017-10-01

    The electrical characteristics of funnel-shaped silicon nanowire (SiNW) solar cells are introduced and numerically analyzed. The funnel-shaped NW consists of a cylinder over a conical unit. Its aim is to maximize the optical absorption over a large wavelength range and hence the electrical efficiency by increasing the number of resonance wavelengths or by enlarging the resonance wavelength range. The conical part has different radii in the axial direction, which increases the number of resonance wavelengths. Further, the coupling between the supported modes by the upper cylinder and the lower tapered cone offers multiple optical resonances required for broadband absorption. The optical characteristics and generation rates through the studied design are obtained using 3-D finite difference time domain. However, the electrical properties are calculated using finite element via the Lumerical device software package. In this regard, radial and axial junctions are examined for the suggested design and compared with the conventional cylindrical SiNW counterpart. In this investigation, short circuit current density, open circuit voltage, fill factor, and power conversion efficiency (PCE) are simulated to quantify the optoelectronic performance of the reported design. Furthermore, the effects of the doping concentration and carrier lifetime on the performance of the funnel-shaped design are reported. The proposed SiNWs offer PCE and short circuit density of 12.7% and 27.6 mA/cm2, respectively, for the axial junction. However, the funnel design with core-shell junction shows an efficiency and short-circuit current (Jsc) of 14.13% and 31.94 mA/cm2, respectively. Therefore, the suggested design has higher efficiency than 6.4% and 9.6% of the conventional cylindrical SiNWs according to the axial and core shell junctions, respectively.

  14. Biosensors

    Indian Academy of Sciences (India)

    systems and hence into drinking water. Important targets for pollution biosensors now include anionic pollutants such as nitrates and phosphates. The area of biosensor development is of great importance to military and defense applications such as detection of chemical and biological species used in weapons.

  15. Solvent Vapor Growth of Axial Heterostructure Nanowires with Multiple Alternating Segments of Silicon and Germanium.

    Science.gov (United States)

    Flynn, Grace; Ramasse, Quentin M; Ryan, Kevin M

    2016-01-13

    Herein, we report the formation of multisegment Si-Ge axial heterostructure nanowires in a wet chemical synthetic approach. These nanowires are grown by the liquid injection of the respective silicon and germanium precursors into the vapor phase of an organic solvent in which a tin-coated stainless steel substrate is placed. The Si-Ge transition is obtained by sequential injection with the more difficult Ge-Si transition enabled by inclusion of a quench sequence in the reaction. This approach allows for alternating between pure Si and pure Ge segments along the entire nanowire length with good control of the respective segment dimensions. The multisegment heterostructure nanowires presented are Ge-Si, Si-Ge-Si, Ge-Si-Ge, Si-Ge-Si-Ge, and Si-Ge-Si-Ge-Si-Ge. The interfacial abruptness of the Ge to Si interface is also determined through the use of aberration corrected scanning transmission electron microscopy and electron energy loss spectroscopy.

  16. 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.

  17. 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.

  18. A model study of surface state on optical bandgap of silicon nanowires

    African Journals Online (AJOL)

    It is observed that visible PL in silicon nanowires is due to quantum confinement and surface passivation. But the energy recombination of electron and holes in the quantum confined nanostructures is responsible for the visible PL. In this work, models from quantum bandgap and photoluminescence intensity are adopted to ...

  19. 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

  20. 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

  1. Silicon nanowires as a rechargeable template for hydride transfer in redox biocatalysis

    Science.gov (United States)

    Lee, Hwa Young; Kim, Jae Hong; Son, Eun Jin; Park, Chan Beum

    2012-11-01

    We report a new possible application of hydrogen-terminated silicon nanowires (H-SiNWs) as a rechargeable template for hydride transfer in redox biocatalysis. H-SiNWs transfer hydride efficiently to regenerate NADH by oxidizing Si-Hx bonds. The oxidized H-SiNWs were readily recharged for the continuous regeneration of NADH and enzymatic reactions.

  2. 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

  3. 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...

  4. Silicon Nanowires Grown on Metal Substrates via Self-Catalyst Mechanism

    Czech Academy of Sciences Publication Activity Database

    Dřínek, Vladislav; Klementová, Mariana; Fajgar, Radek; Dytrych, Pavel

    2015-01-01

    Roč. 160, DEC 1 (2015), s. 109-112 ISSN 0167-577X R&D Projects: GA ČR GA13-25747S Institutional support: RVO:67985858 ; RVO:68378271 Keywords : CVD * silicon * nanowire Subject RIV: CA - Inorganic Chemistry Impact factor: 2.437, year: 2015

  5. 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.

  6. 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.

    2018-03-01

    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.

  7. Cell number per spheroid and electrical conductivity of nanowires influence the function of silicon nanowired human cardiac spheroids.

    Science.gov (United States)

    Tan, Yu; Richards, Dylan; Coyle, Robert C; Yao, Jenny; Xu, Ruoyu; Gou, Wenyu; Wang, Hongjun; Menick, Donald R; Tian, Bozhi; Mei, Ying

    2017-03-15

    Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) provide an unlimited cell source to treat cardiovascular diseases, the leading cause of death worldwide. However, current hiPSC-CMs retain an immature phenotype that leads to difficulties for integration with adult myocardium after transplantation. To address this, we recently utilized electrically conductive silicon nanowires (e-SiNWs) to facilitate self-assembly of hiPSC-CMs to form nanowired hiPSC cardiac spheroids. Our previous results showed addition of e-SiNWs effectively enhanced the functions of the cardiac spheroids and improved the cellular maturation of hiPSC-CMs. Here, we examined two important factors that can affect functions of the nanowired hiPSC cardiac spheroids: (1) cell number per spheroid (i.e., size of the spheroids), and (2) the electrical conductivity of the e-SiNWs. To examine the first factor, we prepared hiPSC cardiac spheroids with four different sizes by varying cell number per spheroid (∼0.5k, ∼1k, ∼3k, ∼7k cells/spheroid). Spheroids with ∼3k cells/spheroid was found to maximize the beneficial effects of the 3D spheroid microenvironment. This result was explained with a semi-quantitative theory that considers two competing factors: 1) the improved 3D cell-cell adhesion, and 2) the reduced oxygen supply to the center of spheroids with the increase of cell number. Also, the critical role of electrical conductivity of silicon nanowires has been confirmed in improving tissue function of hiPSC cardiac spheroids. These results lay down a solid foundation to develop suitable nanowired hiPSC cardiac spheroids as an innovative cell delivery system to treat cardiovascular diseases. Cardiovascular disease is the leading cause of death and disability worldwide. Due to the limited regenerative capacity of adult human hearts, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have received significant attention because they provide a patient specific

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Simple and controlled single electron transistor based on doping modulation in silicon nanowires

    Science.gov (United States)

    Hofheinz, M.; Jehl, X.; Sanquer, M.; Molas, G.; Vinet, M.; Deleonibus, S.

    2006-10-01

    A simple and highly reproducible single electron transistor (SET) has been fabricated using gated silicon nanowires. The structure is a metal-oxide-semiconductor field-effect transistor made on silicon-on-insulator thin films. The channel of the transistor is the Coulomb island at low temperature. Two silicon nitride spacers deposited on each side of the gate create a modulation of doping along the nanowire that creates tunnel barriers. Such barriers are fixed and controlled, like in metallic SETs. The period of the Coulomb oscillations is set by the gate capacitance of the transistor and therefore controlled by lithography. The source and drain capacitances have also been characterized. This design could be used to build more complex SET devices.

  13. Enhanced lithium ion battery cycling of silicon nanowire anodes by template growth to eliminate silicon underlayer islands.

    Science.gov (United States)

    Cho, Jeong-Hyun; Picraux, S Tom

    2013-01-01

    It is well-known that one-dimensional nanostructures reduce pulverization of silicon (Si)-based anode materials during Li ion cycling because they allow lateral relaxation. However, even with improved designs, Si nanowire-based structures still exhibit limited cycling stability for extended numbers of cycles, with the specific capacity retention with cycling not showing significant improvements over commercial carbon-based anode materials. We have found that one important reason for the lack of long cycling stability can be the presence of milli- and microscale Si islands which typically form under nanowire arrays during their growth. Stress buildup in these Si island underlayers with cycling results in cracking, and the loss of specific capacity for Si nanowire anodes, due to progressive loss of contact with current collectors. We show that the formation of these parasitic Si islands for Si nanowires grown directly on metal current collectors can be avoided by growth through anodized aluminum oxide templates containing a high density of sub-100 nm nanopores. Using this template approach we demonstrate significantly enhanced cycling stability for Si nanowire-based lithium-ion battery anodes, with retentions of more than ~1000 mA·h/g discharge capacity over 1100 cycles.

  14. 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....

  15. Orientation-dependent interfacial mobility governs the anisotropic swelling in lithiated silicon nanowires.

    Science.gov (United States)

    Yang, Hui; Huang, Shan; Huang, Xu; Fan, Feifei; Liang, Wentao; Liu, Xiao Hua; Chen, Long-Qing; Huang, Jian Yu; Li, Ju; Zhu, Ting; Zhang, Sulin

    2012-04-11

    Recent independent experiments demonstrated that the lithiation-induced volume expansion in silicon nanowires, nanopillars, and microslabs is highly anisotropic, with predominant expansion along the direction but negligibly small expansion along the direction. The origin of such anisotropic behavior remains elusive. Here, we develop a chemomechanical model to study the phase evolution and morphological changes in lithiated silicon nanowires. The model couples the diffusive reaction of lithium with the lithiation-induced elasto-plastic deformation. We show that the apparent anisotropic swelling is critically controlled by the orientation-dependent mobility of the core-shell interface, i.e., the lithiation reaction rate at the atomically sharp phase boundary between the crystalline core and the amorphous shell. Our results also underscore the importance of structural relaxation by plastic flow behind the moving phase boundary, which is essential to quantitative prediction of the experimentally observed morphologies of lithiated silicon nanowires. The study sheds light on the lithiation-mediated failure in nanowire-based electrodes, and the modeling framework provides a basis for simulating the morphological evolution, stress generation, and fracture in high-capacity electrodes for the next-generation lithium-ion batteries. © 2012 American Chemical Society

  16. 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.

  17. Dislocation-free axial InAs-on-GaAs nanowires on silicon

    Science.gov (United States)

    Beznasyuk, Daria V.; Robin, Eric; Den Hertog, Martien; Claudon, Julien; Hocevar, Moïra

    2017-09-01

    We report on the growth of axial InAs-on-GaAs nanowire heterostructures on silicon by molecular beam epitaxy using 20 nm diameter Au catalysts. First, the growth parameters of the GaAs nanowire segment were optimized to achieve a pure wurtzite crystal structure. Then, we developed a two-step growth procedure to enhance the yield of vertical InAs-on-GaAs nanowires. We achieved 90% of straight InAs-on-GaAs nanowires by further optimizing the growth parameters. We investigated the composition change at the interface by energy dispersive x-ray spectroscopy and the nanowire crystal structure by transmission electron microscopy. The composition of the nominal InAs segment is found to be In x Ga1-x As with x = 0.85 and corresponds to 6% of lattice mismatch with GaAs. Strain mapping performed by the geometrical phase analysis of high-resolution images revealed a dislocation-free GaAs/In0.85Ga0.15As interface. In conclusion, we successfully fabricated highly mismatched heterostructures, confirming the prediction that axial GaAs/In0.85Ga0.15As interfaces are pseudomorphic in nanowires with a diameter smaller than 40 nm.

  18. Adjustable optical response of amorphous silicon nanowires integrated with thin films.

    Science.gov (United States)

    Dhindsa, Navneet; Walia, Jaspreet; Pathirane, Minoli; Khodadad, Iman; Wong, William S; Saini, Simarjeet Singh

    2016-04-08

    We experimentally demonstrate a new optical platform by integrating hydrogenated amorphous silicon nanowire arrays with thin films deposited on transparent substrates like glass. A 535 nm thick thin film is anisotropically etched to fabricate vertical nanowire arrays of 100 nm diameter arranged in a square lattice. Adjusting the nanowire length, and consequently the thin film thickness permits the optical properties of this configuration to be tuned for either transmission filter response or enhanced broadband absorption. Vivid structural colors are also achieved in reflection and transmission. The optical properties of the platform are investigated for three different etch depths. Transmission filter response is achieved for a configuration with nanowires on glass without any thin film. Alternatively, integrating thin film with nanowires increases the absorption efficiency by ∼97% compared to the thin film starting layer and by ∼78% over nanowires on glass. The ability to tune the optical response of this material in this fashion makes it a promising platform for high performance photovoltaics, photodetectors and sensors.

  19. Geometry and temperature effects on the threshold voltage characteristics of silicon nanowire MOS transistors

    Science.gov (United States)

    Wong, Hei; Yu, Qanqun; Dong, Shurong; Kakushima, Kuniyuki; Iwai, Hiroshi

    2017-12-01

    This work reports the observations of different geometry and temperature dependencies of electrical characteristics of silicon nanowire transistors with gate length of a couple microns. Several abnormal characteristics degradations were observed. As the gate lengths as well as the source/drain doping level of the devices under investigation were well beyond the punchthrough conditions, these observed characteristic degradations should not be due to conventional short-channel effects. We ascribed these observations to the charge transport along the corners/boundaries of the nanowires. Current enhancements were observed because of the higher mobility and larger density of states at the corners where the surface states have opposite effects on these parameters. Temperature dependence of the threshold voltage shows a linear decrease as the temperature increases. This trend is ascribed to the charge states at oxide/nanowire interfaces. Corners and surfaces of nanowire thus should play an important role for ultra-short nanowire transistors and that calls for shape of nanowire optimization for device design.

  20. 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...... by computing the mean free path, sample-averaged conductance hGi, and sample-to-sample variations stdG as a function of energy, doping density, wire length, and the radial dopant profile. Our main findings are (i) the main trends can be predicted quantitatively based on the scattering properties of single...

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. Detailed Time-Resolved Spectral Analysis of Ultra-Fast Four-Wave Mixing in Silicon Nanowires

    DEFF Research Database (Denmark)

    Ma, M.; Galili, Michael; Oxenløwe, Leif Katsuo

    2011-01-01

    We present an experimental set-up for measuring spectral and temporal nonlinear responses of silicon nanowires. We find that switching windows are independent of device lengths and there is no memory effect of the FWM response.......We present an experimental set-up for measuring spectral and temporal nonlinear responses of silicon nanowires. We find that switching windows are independent of device lengths and there is no memory effect of the FWM response....

  6. Wavelength Conversion with Large Signal-Idler Separation using Discrete Four-Wave Mixing in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Hu, Hao; Peucheret, Christophe; Pu, Minhao

    2012-01-01

    We have demonstrated wavelength conversion over 468 nm based on discrete bands phase matching in a silicon nanowire. CW light is converted from 1258 nm to 1726 nm with a CW pump at 1455 nm.......We have demonstrated wavelength conversion over 468 nm based on discrete bands phase matching in a silicon nanowire. CW light is converted from 1258 nm to 1726 nm with a CW pump at 1455 nm....

  7. The influence of H{sub 2}O{sub 2} concentration to the structure of silicon nanowire growth by metal-assisted chemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Omar, Hafsa, E-mail: mrshafsaomar@gmail.com [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA(UiTM), 40450 Shah Alam, Selangor (Malaysia); Jani, Abdul Mutalib Md., E-mail: abdmutalib@perlis.uitm.edu.my; Abdullah, Saifollah, E-mail: saifollah@salam.utm.edu.my [Faculty of Applied Sciences, Universiti Teknologi MARA(UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, Mohamad, E-mail: nanouitm@gmail.com [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA(UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA(UiTM), p40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    A simple and low cost method to produce well aligned silicon nanowires at large areas using Ag-assisted chemical etching at room temperature were presented. The structure of silicon nanowires growth by metal-assisted chemical etching was observed. Prior to the etching, the silicon nanowires were prepared by electroless metal deposited (EMD) in solution containing hydrofluoric acid and hydrogen peroxide in Teflon vessel. The silver particle was deposited on substrate by immersion in hydrofluoric acid and silver nitrate solution for sixty second. The silicon nanowires were growth in different hydrogen peroxide concentration which are 0.3M, 0.4M, 0.5M and 0.6M and 0.7M.The influence of hydrogen peroxide concentration to the formation of silicon nanowires was studied. The morphological properties of silicon nanowires were investigated using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS).

  8. Enhanced photocatalytic degradation of methylene blue by metal-modified silicon nanowires

    International Nuclear Information System (INIS)

    Brahiti, N.; Hadjersi, T.; Menari, H.; Amirouche, S.; El Kechai, O.

    2015-01-01

    Highlights: • SiNWs modified with Pd, Au and Pt were used as photocatalysts to degrade MB. • Yield of photodegardation increases with UV irradiation time. • SiNWs modified with Pd nanoparticles show the best photocatalytic activity. • A degradation of 97% was obtained after 200 min of UV irradiation. - Abstract: Silicon nanowires (SiNWs) modified with Au, Pt and Pd nanoparticles were used as heterogeneous photocatalysts for the photodegradation of methylene blue in water under UV light irradiation. The modification of SiNWs was carried out by deposition of metal nanoparticles using the electroless metal deposition (EMD) technique. The effect of metal nanoparticles deposition time on the photocatalytic activity was studied. It was found that the photocatalytic activity of modified SiNWs was enhanced when the deposition time of metal nanoparticles was increased. In addition of modified SiNWs with Pt, Au and Pd nanoparticles, oxidized silicon substrate (Ox-Si), oxidized silicon nanowires (Ox-SiNWs) and hydrogen-terminated silicon nanowires (H-SiNWs) were also evaluated for the photodegradation of methylene blue

  9. Crystalline-amorphous core-shell silicon nanowires for high capacity and high current battery electrodes.

    Science.gov (United States)

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

    2009-01-01

    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 ( approximately 1000 mAh/g, 3 times of carbon) with approximately 90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, approximately 20 times of carbon at 1 h rate).

  10. Scattering cross section of metal catalyst atoms in silicon nanowires

    DEFF Research Database (Denmark)

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

    2010-01-01

    strength of the different metal atoms. We find that Au, Ag, and Cu impurities have very similar scattering cross sections, while Al differs from the rest. Impurities located in the center of the wires scatter significantly more than impurities close to or at the surface. The results for nanowires...

  11. 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

  12. 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.

  13. 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.

  14. Silicon Tunneling Field Effect Transistors with a Hemicylindrical Nanowire Channel for Ultra-Low Power Application

    Science.gov (United States)

    Park, Byung-Gook; Sun, Min-Chul; Kim, Sang Wan

    In order to decrease the threshold voltage while maintaining the OFF current low, reduction of the subthreshold swing is essential in field effect transistors (FETs). To reduce the subthreshold swing below 60 mV/decade, inter-band tunneling can be used for injection of carriers and the device that utilizes such a mechanism is tunneling field effect transistor (TFET). Silicon(Si) TFETs, which are favored due to their compatibility with currently dominant complementary metal-oxide-semiconductor (CMOS) technology, suffer from low ON current because of the relatively large bandgap of Si. The ON current of Si TFETs can be increased by field and area enhancement in a cylindrical nanowire channel. Numerical analysis has confirmed that the cylindrical channel structure shows significantly higher tunneling rate and wider tunneling area than the double gate structure. Si TFETs with a hemicylindrical nanowire channel are fabricated and characterized, and the effectiveness of nanowire channel approach is demonstrated.

  15. Hybrid Si nanowire/amorphous silicon FETs for large-area image sensor arrays.

    Science.gov (United States)

    Wong, William S; Raychaudhuri, Sourobh; Lujan, René; Sambandan, Sanjiv; Street, Robert A

    2011-06-08

    Silicon nanowire (SiNW) field-effect transistors (FETs) were fabricated from nanowire mats mechanically transferred from a donor growth wafer. Top- and bottom-gate FET structures were fabricated using a doped a-Si:H thin film as the source/drain (s/d) contact. With a graded doping profile for the a-Si:H s/d contacts, the off-current for the hybrid nanowire/thin-film devices was found to decrease by 3 orders of magnitude. Devices with the graded contacts had on/off ratios of ∼10(5), field-effect mobility of ∼50 cm(2)/(V s), and subthreshold swing of 2.5 V/decade. A 2 in. diagonal 160 × 180 pixel image sensor array was fabricated by integrating the SiNW backplane with an a-Si:H p-i-n photodiode.

  16. Effect of phonon transport on the Seebeck coefficient and thermal conductivity of silicon nanowire arrays

    Science.gov (United States)

    Sadhu, Jyothi Swaroop

    Thermoelectrics enable solid-state conversion of heat to electricity by the Seebeck effect, but must provide scalable and cost-effective technology for practical waste heat harvesting. This dissertation explores the thermoelectric properties of electrochemically etched silicon nanowires through experiments, complemented by charge and thermal transport theories. Electrolessly etched silicon nanowires show anomalously low thermal conductivity that has been attributed to the increased scattering of heat conducting phonons from the surface disorder introduced by etching. The reduction is below the incoherent limit for phonon scattering at the boundary, the so-called Casimir limit. A new model of partially coherent phonon transport shows that correlated multiple scattering of phonons off resonantly matched rough surfaces can indeed lead to thermal conductivity below the Casimir limit. Using design guidelines from the theory, silicon nanowires of controllable surface roughness are fabricated using metal-assisted chemical etching. Extensive characterization of the nanowire surfaces using transmission electron microscopy provides surface roughness parameters that are important in testing transport theories. The second part of the dissertation focuses on the implications of increased phonon scattering on the Seebeck coefficient, which is a cumulative effect of non-equilibrium amongst charge carriers and phonons. A novel frequency-domain technique enables simultaneous measurements of the Seebeck coefficient and the thermal conductivity of nanowire arrays. The frequency response measurements isolate the parasitic contributions thus improving upon existing techniques for cross-plane thermoelectric measurements. While the thermal conductivity of nanowires reduces significantly with increased roughness, there is also a significant reduction in the Seebeck coefficient over a wide range of doping. Theoretical fitting of the data reveals that such reduction results from the

  17. 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.

  18. Core-shell homojunction silicon vertical nanowire tunneling field-effect transistors

    Science.gov (United States)

    Yoon, Jun-Sik; Kim, Kihyun; Baek, Chang-Ki

    2017-01-01

    We propose three-terminal core-shell (CS) silicon vertical nanowire tunneling field-effect transistors (TFETs), which can be fabricated by conventional CMOS technology. CS TFETs show lower subthreshold swing (SS) and higher on-state current than conventional TFETs through their high surface-to-volume ratio, which increases carrier-tunneling region with no additional device area. The on-state current can be enhanced by increasing the nanowire height, decreasing equivalent oxide thickness (EOT) or creating a nanowire array. The off-state current is also manageable for power saving through selective epitaxial growth at the top-side nanowire region. CS TFETs with an EOT of 0.8 nm and an aspect ratio of 20 for the core nanowire region provide the largest drain current ranges with point SS values below 60 mV/dec and superior on/off current ratio under all operation voltages of 0.5, 0.7, and 1.0 V. These devices are promising for low-power applications at low fabrication cost and high device density. PMID:28112273

  19. Core-shell homojunction silicon vertical nanowire tunneling field-effect transistors

    Science.gov (United States)

    Yoon, Jun-Sik; Kim, Kihyun; Baek, Chang-Ki

    2017-01-01

    We propose three-terminal core-shell (CS) silicon vertical nanowire tunneling field-effect transistors (TFETs), which can be fabricated by conventional CMOS technology. CS TFETs show lower subthreshold swing (SS) and higher on-state current than conventional TFETs through their high surface-to-volume ratio, which increases carrier-tunneling region with no additional device area. The on-state current can be enhanced by increasing the nanowire height, decreasing equivalent oxide thickness (EOT) or creating a nanowire array. The off-state current is also manageable for power saving through selective epitaxial growth at the top-side nanowire region. CS TFETs with an EOT of 0.8 nm and an aspect ratio of 20 for the core nanowire region provide the largest drain current ranges with point SS values below 60 mV/dec and superior on/off current ratio under all operation voltages of 0.5, 0.7, and 1.0 V. These devices are promising for low-power applications at low fabrication cost and high device density.

  20. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    OpenAIRE

    Tao Yang; Liqin Zhang; Xinmei Hou; Junhong Chen; Kuo-Chih Chou

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS...

  1. Thermal Conductivity Suppression in Nanostructured Silicon and Germanium Nanowires

    Science.gov (United States)

    Özden, Ayberk; Kandemir, Ali; Ay, Feridun; Perkgöz, Nihan Kosku; Sevik, Cem

    2016-03-01

    The inherent low lattice thermal conductivity (TC) of semiconductor nanowires (s-NW) due to one-dimensional phonon confinement might provide a solution for the long-lasting figure-of-merit problem for highly efficient thermoelectric (TE) applications. Standalone diameter modulation or alloying of s-NW serve as a toolkit for TC control, but realizing the full potential of nanowires requires new atomic-scale designs, growth, characterization, and understanding of the physical mechanisms behind the structure-property (TC) relationship. Before undertaking time-consuming and expensive experimental work, molecular dynamics (MD) simulations serve as an excellent probe to investigate new designs and understand how nanostructures affect thermal transport properties through their capability to capture various phenomena such as phonon boundary scattering, phonon coherence resonance, and phonon backscattering. On the other hand, because different research groups use different structural and MD parameters in their simulations, it is rather difficult to make comparisons between different nanostructures and select appropriate ones for potential TE applications. Therefore, in this work, we systematically investigated pristine, core-shell (C-S), holey (H-N), superlattice (SL), sawtooth (ST), and superlattice sawtooth (SL-ST) nanowires with identical structural parameters. Specifically, we aim to compare the relative TC reduction achieved by these nanostructures with respect to pristine nanowires in order to propose the best structural design with the lowest lattice TC, using Green-Kubo method-based equilibrium molecular dynamics simulations at 300 K. Our results show that the TC can be minimized by changing specific parameters such as the core diameter and monolayer separation for C-S, H-N, and ST structures. In the case of SL structures, the TC is found to be independent of these parameters. However, surface roughness in the form of a ST morphology provides a TC value below 2 W

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Modification of silicon nitride and silicon carbide surfaces for food and biosensor applications

    OpenAIRE

    Rosso, M.

    2009-01-01

    Silicon-rich silicon nitride (SixN4, x > 3) is a robust insulating material widely used for the coating of microdevices: its high chemical and mechanical inertness make it a material of choice for the reinforcement of fragile microstructures (e.g. suspended microcantilevers, micro-fabricated membranes-“microsieves”) or for the coating of the exposed surfaces of sensors (field-effect transistors, waveguide optical detectors). To a more limited extent, silicon carbide (SiC) can find similar ...

  9. Monolithic InGaAs Nanowire Array Lasers on Silicon-on-Insulator Operating at Room Temperature.

    Science.gov (United States)

    Kim, Hyunseok; Lee, Wook-Jae; Farrell, Alan C; Morales, Juan S D; Senanayake, Pradeep; Prikhodko, Sergey V; Ochalski, Tomasz J; Huffaker, Diana L

    2017-06-14

    Chip-scale integrated light sources are a crucial component in a broad range of photonics applications. III-V semiconductor nanowire emitters have gained attention as a fascinating approach due to their superior material properties, extremely compact size, and capability to grow directly on lattice-mismatched silicon substrates. Although there have been remarkable advances in nanowire-based emitters, their practical applications are still in the early stages due to the difficulties in integrating nanowire emitters with photonic integrated circuits. Here, we demonstrate for the first time optically pumped III-V nanowire array lasers monolithically integrated on silicon-on-insulator (SOI) platform. Selective-area growth of InGaAs/InGaP core/shell nanowires on an SOI substrate enables the nanowire array to form a photonic crystal nanobeam cavity with superior optical and structural properties, resulting in the laser to operate at room temperature. We also show that the nanowire array lasers are effectively coupled with SOI waveguides by employing nanoepitaxy on a prepatterned SOI platform. These results represent a new platform for ultracompact and energy-efficient optical links and unambiguously point the way toward practical and functional nanowire lasers.

  10. Modification of silicon nitride and silicon carbide surfaces for food and biosensor applications

    NARCIS (Netherlands)

    Rosso, M.

    2009-01-01

    Silicon-rich silicon nitride (SixN4, x > 3) is a robust insulating material widely used for the coating of microdevices: its high chemical and mechanical inertness make it a material of choice for the reinforcement of fragile microstructures (e.g. suspended microcantilevers, micro-fabricated

  11. A room temperature light source based on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-31

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

  12. 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

  13. Chemical surface modifications for the development of silicon-based label-free integrated optical (IO) biosensors: a review.

    Science.gov (United States)

    Bañuls, María-José; Puchades, Rosa; Maquieira, Ángel

    2013-05-13

    Increasing interest has been paid to label-free biosensors in recent years. Among them, refractive index (RI) optical biosensors enable high density and the chip-scale integration of optical components. This makes them more appealing to help develop lab-on-a-chip devices. Today, many RI integrated optical (IO) devices are made using silicon-based materials. A key issue in their development is the biofunctionalization of sensing surfaces because they provide a specific, sensitive response to the analyte of interest. This review critically discusses the biofunctionalization procedures, assay formats and characterization techniques employed in setting up IO biosensors. In addition, it provides the most relevant results obtained from using these devices for real sample biosensing. Finally, an overview of the most promising future developments in the fields of chemical surface modification and capture agent attachment for IO biosensors follows. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Vapor-liquid-solid growth of silicon and silicon germanium nanowires

    Science.gov (United States)

    Nimmatoori, Pramod

    2009-12-01

    Si and Si1-xGex nanowires are promising materials with potential applications in various disciplines of science and technology. Small diameter nanowires can act as model systems to study interesting phenomena such as tunneling that occur in the nanometer regime. Furthermore, technical challenges in fabricating nanoscale size devices from thin films have resulted in interest and research on nanowires. In this perspective, vertical integrated nanowire field effect transistors (VINFETs) fabricated from Si nanowires are promising devices that offer better control on device properties and push the transistor architecture into the third dimension potentially enabling ultra-high transistor density circuits. Transistors fabricated from Si/Si 1-xGex nanowires have also been proposed that can have high carrier mobility. In addition, the Si and Si1-xGe x nanowires have potential to be used in various applications such as sensing, thermoelectrics and solar cells. Despite having considerable potential, the understanding of the vapor-liquid-solid (VLS) mechanism utilized to fabricate these wires is still rudimentary. Hence, the objective of this thesis is to understand the effects of nanoscale size and the role of catalyst that mediates the wire growth on the growth rate of Si and Si1-xGe x nanowires and interfacial abruptness in Si/Si1-xGe x axial heterostructure nanowires. Initially, the growth and structural properties of Si nanowires with tight diameter distribution grown from 10, 20 and 50 nm Au particles dispersed on a polymer-modified substrate was studied. A nanoparticle application process was developed to disperse Au particles on the substrate surface with negligible agglomeration and sufficient density. The growth temperature and SiH4 partial pressure were varied to optimize the growth conditions amenable to VLS growth with smooth wire morphology and negligible Si thin film deposition on wire sidewalls. The Si nanowire growth rate was studied as a function of growth

  15. 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 (<3s), a wider linear response from 0.01 to 1.3mM with an ultralow LOD=5µm, and the ultrahigh sensitivities of 131.31 and 481.20µAmM -1 cm -2 for the detections of glucose and hydrogen peroxide (H 2 O 2 ), respectively. Furthermore, the 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.

  16. 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.

  17. Single nanowire electrode electrochemistry of silicon anode by in situ atomic force microscopy: solid electrolyte interphase growth and mechanical properties.

    Science.gov (United States)

    Liu, Xing-Rui; Deng, Xin; Liu, Ran-Ran; Yan, Hui-Juan; Guo, Yu-Guo; Wang, Dong; Wan, Li-Jun

    2014-11-26

    Silicon nanowires (SiNWs) have attracted great attention as promising anode materials for lithium ion batteries (LIBs) on account of their high capacity and improved cyclability compared with bulk silicon. The interface behavior, especially the solid electrolyte interphase (SEI), plays a significant role in the performance and stability of the electrodes. We report herein an in situ single nanowire atomic force microscopy (AFM) method to investigate the interface electrochemistry of silicon nanowire (SiNW) electrode. The morphology and Young's modulus of the individual SiNW anode surface during the SEI growth were quantitatively tracked. Three distinct stages of the SEI formation on the SiNW anode were observed. On the basis of the potential-dependent morphology and Young's modulus evolution of SEI, a mixture-packing structural model was proposed for the SEI film on SiNW anode.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

    2016-11-01

    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 >107 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.

  4. 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.

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

    Science.gov (United States)

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

    2014-09-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Mingyu; Kaizawa, Takuya; Arita, Masashi [Graduate School of Information Science and Technology, Hokkaido Univ., Sapporo, 060-0814 (Japan); Fujiwara, Akira; Ono, Yukinori [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, 243-0198 (Japan); Inokawa, Hiroshi [Research Institute of Electronics, Shizuoka Univ., 3-5-1, Johoku, Hamamatsu, 432-8011 (Japan); Choi, Jung-Bum [Physics and Research Institute of NanoScience and Technology, Chungbuk National Univ., Cheongju, Chungbuk 361-763 (Korea, Republic of); Takahashi, Yasuo, E-mail: y-taka@nano.ist.hokudai.ac.j [Graduate School of Information Science and Technology, Hokkaido Univ., Sapporo, 060-0814 (Japan)

    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.

  7. Silicon nanowire charge-trap memory incorporating self-assembled iron oxide quantum dots.

    Science.gov (United States)

    Huang, Ruo-Gu; Heath, James R

    2012-11-19

    Charge-trap non-volatile memory devices based upon the precise integration of quantum dot storage elements with silicon nanowire field-effect transistors are described. Template-assisted assembly yields an ordered array of FeO QDs within the trenches that separate highly aligned SiNWs, and injected charges are reversibly stored via Fowler-Nordheim tunneling into the QDs. Stored charges shift the transistor threshold voltages, providing the basis for a memory device. Quantum dot size is found to strongly influence memory performance metrics. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    KAUST Repository

    Yao, Yan

    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.

  9. 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.

  10. 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.

  11. Lithium Insertion In Silicon Nanowires: An ab Initio Study

    KAUST Repository

    Zhang, Qianfan

    2010-09-08

    The ultrahigh specific lithium ion storage capacity of Si nanowires (SiNWs) has been demonstrated recently and has opened up exciting opportunities for energy storage. However, a systematic theoretical study on lithium insertion in SiNWs remains a challenge, and as a result, understanding of the fundamental interaction and microscopic dynamics during lithium insertion is still lacking. This paper focuses on the study of single Li atom insertion into SiNWs with different sizes and axis orientations by using full ab initio calculations. We show that the binding energy of interstitial Li increases as the SiNW diameter grows. The binding energies at different insertion sites, which can be classified as surface, intermediate, and core sites, are quite different. We find that surface sites are energetically the most favorable insertion positions and that intermediate sites are the most unfavorable insertion positions. Compared with the other growth directions, the [110] SiNWs with different diameters always present the highest binding energies on various insertion locations, which indicates that [110] SiNWs are more favorable by Li doping. Furthermore, we study Li diffusion inside SiNWs. The results show that the Li surface diffusion has a much higher chance to occur than the surface to core diffusion, which is consistent with the experimental observation that the Li insertion in SiNWs is layer by layer from surface to inner region. After overcoming a large barrier crossing surface-to-intermediate region, the diffusion toward center has a higher possibility to occur than the inverse process. © 2010 American Chemical Society.

  12. 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.

  13. 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.

  14. Tuning the electronic band-gap of fluorinated 3C-silicon carbide nanowires

    Science.gov (United States)

    Miranda Durán, Álvaro; Trejo Baños, Alejandro; Pérez, Luis Antonio; Cruz Irisson, Miguel

    The possibility of control and modulation of the electronic properties of silicon carbide nanowires (SiCNWs) by varying the wire diameter is well known. SiCNWs are particularly interesting and technologically important, due to its electrical and mechanical properties, allowing the development of materials with specific electronic features for the design of stable and robust electronic devices. Tuning the band gap by chemical surface passivation constitutes a way for the modification of the electronic band gap of these nanowires. We present, the structural and electronic properties of fluorinated SiCNWs, grown along the [111] crystallographic direction, which are investigated by first principles. We consider nanowires with six diameters, varying from 0.35 nm to 2.13 nm, and eight random covering schemes including fully hydrogen- and fluorine terminated ones. Gibbs free energy of formation and electronic properties were calculated for the different surface functionalization schemes and diameters considered. The results indicate that the stability and band gap of SiCNWs can be tuned by surface passivation with fluorine atoms This work was supported by CONACYT infrastructure project 252749 and UNAM-DGAPA-PAPIIT IN106714. A.M. would like to thank for financial support from CONACyT-Retención. Computing resources from proyect SC15-1-IR-27 of DGTIC-UNAM are acknowledged.

  15. Spin transport and Hanle effect in silicon nanowires using graphene tunnel barriers

    Science.gov (United States)

    van't Erve, O. M. J.; Friedman, A. L.; Li, C. H.; Robinson, J. T.; Connell, J.; Lauhon, L. J.; Jonker, B. T.

    2015-06-01

    Spin-based devices offer non-volatile, scalable, low power and reprogrammable functionality for emerging device technologies. Here we fabricate nanoscale spintronic devices with ferromagnetic metal/single-layer graphene tunnel barriers used to generate spin accumulation and spin currents in a silicon nanowire transport channel. We report the first observation of spin precession via the Hanle effect in both local three-terminal and non-local spin-valve geometries, providing a direct measure of spin lifetimes and confirmation of spin accumulation and pure spin transport. The use of graphene as the tunnel barrier provides a low-resistance area product contact and clean magnetic switching characteristics, because it smoothly bridges the nanowire and minimizes complicated magnetic domains that otherwise compromise the magnetic behaviour. Utilizing intrinsic two-dimensional layers such as graphene or hexagonal boron nitride as tunnel contacts on nanowires offers many advantages over conventional materials deposited by vapour deposition, enabling a path to highly scaled electronic and spintronic devices.

  16. 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.

  17. In situ X-ray diffraction studies of (de)lithiation mechanism in silicon nanowire anodes.

    Science.gov (United States)

    Misra, Sumohan; Liu, Nian; Nelson, Johanna; Hong, Seung Sae; Cui, Yi; Toney, Michael F

    2012-06-26

    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(15)Si(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.

  18. 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.

  19. Signal enhancement in nano-Raman spectroscopy by gold caps on silicon nanowires obtained by vapour-liquid-solid growth

    International Nuclear Information System (INIS)

    Christiansen, S H; Becker, M; Fahlbusch, S; Michler, J; Sivakov, V; Andrae, G; Geiger, R

    2007-01-01

    Silicon nanowires grown by the vapour-liquid-solid growth mechanism with gold as the catalyst show gold caps ∼50-400 nm in diameter with an almost ideal hemispherical shape atop a silicon column. These gold caps are extremely well suited for exploiting the tip or surface enhanced Raman scattering effects since they assume the right size on the nanometre scale and a reproducible, almost ideal hemispherical shape. On attaching a nanowire with a gold cap to an atomic force microscopy (AFM) tip, the signal enhancement by the gold nanoparticle can be used to spatially resolve a Raman signal. Applications of this novel nanowire based technical tip enhanced Raman scattering solution are widespread and lie in the fields of biomedical and life sciences as well as security (e.g. detection of bacteria and explosives) and in the field of solid state research, e.g. in silicon technology where the material composition, doping, crystal orientation and lattice strain can be probed by Raman spectroscopy. A prerequisite for obtaining this spatial resolution in nano-Raman spectroscopy is the attachment of a nanowire with a gold cap to an AFM tip. This attachment by welding a nanowire in a scanning electron microscope to an AFM tip is demonstrated in this paper

  20. Signal enhancement in nano-Raman spectroscopy by gold caps on silicon nanowires obtained by vapour liquid solid growth

    Science.gov (United States)

    Christiansen, S. H.; Becker, M.; Fahlbusch, S.; Michler, J.; Sivakov, V.; Andrä, G.; Geiger, R.

    2007-01-01

    Silicon nanowires grown by the vapour-liquid-solid growth mechanism with gold as the catalyst show gold caps ~50-400 nm in diameter with an almost ideal hemispherical shape atop a silicon column. These gold caps are extremely well suited for exploiting the tip or surface enhanced Raman scattering effects since they assume the right size on the nanometre scale and a reproducible, almost ideal hemispherical shape. On attaching a nanowire with a gold cap to an atomic force microscopy (AFM) tip, the signal enhancement by the gold nanoparticle can be used to spatially resolve a Raman signal. Applications of this novel nanowire based technical tip enhanced Raman scattering solution are widespread and lie in the fields of biomedical and life sciences as well as security (e.g. detection of bacteria and explosives) and in the field of solid state research, e.g. in silicon technology where the material composition, doping, crystal orientation and lattice strain can be probed by Raman spectroscopy. A prerequisite for obtaining this spatial resolution in nano-Raman spectroscopy is the attachment of a nanowire with a gold cap to an AFM tip. This attachment by welding a nanowire in a scanning electron microscope to an AFM tip is demonstrated in this paper.

  1. Signal enhancement in nano-Raman spectroscopy by gold caps on silicon nanowires obtained by vapour-liquid-solid growth.

    Science.gov (United States)

    Christiansen, S H; Becker, M; Fahlbusch, S; Michler, J; Sivakov, V; Andrä, G; Geiger, R

    2007-01-24

    Silicon nanowires grown by the vapour-liquid-solid growth mechanism with gold as the catalyst show gold caps approximately 50-400 nm in diameter with an almost ideal hemispherical shape atop a silicon column. These gold caps are extremely well suited for exploiting the tip or surface enhanced Raman scattering effects since they assume the right size on the nanometre scale and a reproducible, almost ideal hemispherical shape. On attaching a nanowire with a gold cap to an atomic force microscopy (AFM) tip, the signal enhancement by the gold nanoparticle can be used to spatially resolve a Raman signal. Applications of this novel nanowire based technical tip enhanced Raman scattering solution are widespread and lie in the fields of biomedical and life sciences as well as security (e.g. detection of bacteria and explosives) and in the field of solid state research, e.g. in silicon technology where the material composition, doping, crystal orientation and lattice strain can be probed by Raman spectroscopy. A prerequisite for obtaining this spatial resolution in nano-Raman spectroscopy is the attachment of a nanowire with a gold cap to an AFM tip. This attachment by welding a nanowire in a scanning electron microscope to an AFM tip is demonstrated in this paper.

  2. Enhanced field emission from ZnO nanowire arrays utilizing MgO buffer between seed layer and silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Si [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Chen, Jiangtao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Mid. Road, Lanzhou 730000 (China); Liu, Jianlin [Quantum Structures Laboratory, Department of Electrical and Computer Engineering, University of California, Riverside, CA 92521 (United States); Qi, Jing, E-mail: qijing@lzu.edu.cn [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, Yuhua, E-mail: wyh@lzu.edu.cn [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2016-11-30

    Highlights: • We obtained ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer. • FE properties of ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer is better than that without MgO buffer. • With MgO buffer, the ZnO seed layer shows lower top-bottom resistance and better electron transport. • The enhanced field emission properties can be attributed to good electron transport in seed layer, good nanowire alignment because of MgO buffer. - Abstract: Field emitters based on ZnO nanowires and other nanomaterials are promising high-brightness electron sources for field emission display, microscopy and other applications. The performance of a ZnO nanowire field emitter is linked to the quality, conductivity and alignment of the nanowires on a substrate, therefore requiring ways to improve these parameters. Here, ZnO nanowire arrays were grown on ZnO seed layer on silicon substrate with MgO buffer between the seed layer and Si. The turn-on field and enhancement factor of these nanowire arrays are 3.79 V/μm and 3754, respectively. These properties are improved greatly compared to those of ZnO nanowire arrays grown on ZnO seed layer without MgO buffer, which are 5.06 V/μm and 1697, respectively. The enhanced field emission properties can be attributed to better electron transport in seed layer, and better nanowire alignment because of MgO buffer.

  3. Low Temperature Characterization of PMOS-type Gate-all-around Silicon nanowire FETs as single-hole-transistors

    Science.gov (United States)

    Hong, B. H.; Hwang, S. W.; Lee, Y. Y.; Son, M. H.; Ahn, D.; Cho, K. H.; Yeo, K. H.; Kim, D.-W.; Jin, G. Y.; Park, D.

    2011-12-01

    We report the single hole tunneling characteristics observed from a PMOS-type gate-all-around silicon nanowire field-effect-transistor with the radius 5 nm and the length 44 nm. The total capacitance of the quantum dot obtained from the measured Coulomb oscillations and Coulomb diamonds matches with the ideal capacitance of the silicon cylinder. It suggests that the observed single hole tunneling is originated from the fabricated structure.

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

    KAUST Repository

    Guo, Wei

    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.

  5. Vertical silicon nanowires as a universal platform for delivering biomolecules into living cells

    Science.gov (United States)

    Shalek, Alex K.; Robinson, Jacob T.; Karp, Ethan S.; Lee, Jin Seok; Ahn, Dae-Ro; Yoon, Myung-Han; Sutton, Amy; Jorgolli, Marsela; Gertner, Rona S.; Gujral, Taranjit S.; MacBeath, Gavin; Yang, Eun Gyeong; Park, Hongkun

    2010-01-01

    A generalized platform for introducing a diverse range of biomolecules into living cells in high-throughput could transform how complex cellular processes are probed and analyzed. Here, we demonstrate spatially localized, efficient, and universal delivery of biomolecules into immortalized and primary mammalian cells using surface-modified vertical silicon nanowires. The method relies on the ability of the silicon nanowires to penetrate a cell’s membrane and subsequently release surface-bound molecules directly into the cell’s cytosol, thus allowing highly efficient delivery of biomolecules without chemical modification or viral packaging. This modality enables one to assess the phenotypic consequences of introducing a broad range of biological effectors (DNAs, RNAs, peptides, proteins, and small molecules) into almost any cell type. We show that this platform can be used to guide neuronal progenitor growth with small molecules, knock down transcript levels by delivering siRNAs, inhibit apoptosis using peptides, and introduce targeted proteins to specific organelles. We further demonstrate codelivery of siRNAs and proteins on a single substrate in a microarray format, highlighting this technology’s potential as a robust, monolithic platform for high-throughput, miniaturized bioassays. PMID:20080678

  6. Enhanced thermal conductivity of epoxy composites filled with silicon carbide nanowires.

    Science.gov (United States)

    Shen, Dianyu; Zhan, Zhaolin; Liu, Zhiduo; Cao, Yong; Zhou, Li; Liu, Yuanli; Dai, Wen; Nishimura, Kazuhito; Li, Chaoyang; Lin, Cheng-Te; Jiang, Nan; Yu, Jinhong

    2017-06-01

    In this study, we report a facile approach to fabricate epoxy composite incorporated with silicon carbide nanowires (SiC NWs). The thermal conductivity of epoxy/SiC NWs composites was thoroughly investigated. The thermal conductivity of epoxy/SiC NWs composites with 3.0 wt% filler reached 0.449 Wm -1  K -1 , approximately a 106% enhancement as compared to neat epoxy. In contrast, the same mass fraction of silicon carbide micron particles (SiC MPs) incorporated into epoxy matrix showed less improvement on thermal conduction properties. This is attributed to the formation of effective heat conduction pathways among SiC NWs as well as a strong interaction between the nanowires and epoxy matrix. In addition, the thermal properties of epoxy/SiC NWs composites were also improved. These results demonstrate that we developed a novel approach to enhance the thermal conductivity of the polymer composites which meet the requirement for the rapid development of the electronic devices.

  7. Morphology, structure and magnetic study of permalloy films electroplated on silicon nanowires

    International Nuclear Information System (INIS)

    Lamrani, S.; Guittoum, A.; Schäfer, R.; Hemmous, M.; Neu, V.; Pofahl, S.; Hadjersi, T.; Benbrahim, N.

    2015-01-01

    We report the effect of deposition potential on the morphology, structure and magnetic properties of Ni 80 Fe 20 (Permalloy: Py) deposits, elaborated by electrochemical process onto silicon nanowires (SiNWs). The morphology of SiNWs and Py/SiNWs were performed with scanning electron microscopy (SEM). The SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. The analysis of X-ray diffraction spectra shows a change in the texture with the deposition potential. The grain size, the lattice parameter and the strain were studied as a function of the deposition potentials. From hysteresis loops, we have shown that the magnetization easy axis is the plane of the samples. - Highlights: • Permalloy deposits were elaborated by electrochemical process onto silicon nanowires (SiNWs). • SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. • The magnetization easy axis was found to be in the plane of samples

  8. Morphology, structure and magnetic study of permalloy films electroplated on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lamrani, S. [Centre de Recherche en Technologie des Semi-Conducteurs pour l’énergétique, 2 Bd Frantz Fanon, BP 140 les 7 merveilles, Algiers (Algeria); Université Mouloud Mammeri, TiziOuzou 15000 (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria); Schäfer, R. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Inst. f. Metallic Materials, Helmholtz str. 20, D-01069 Dresden (Germany); Hemmous, M. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria); Neu, V.; Pofahl, S. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Inst. f. Metallic Materials, Helmholtz str. 20, D-01069 Dresden (Germany); Hadjersi, T. [Centre de Recherche en Technologie des Semi-Conducteurs pour l’énergétique, 2 Bd Frantz Fanon, BP 140 les 7 merveilles, Algiers (Algeria); Benbrahim, N. [Université Mouloud Mammeri, TiziOuzou 15000 (Algeria)

    2015-12-15

    We report the effect of deposition potential on the morphology, structure and magnetic properties of Ni{sub 80}Fe{sub 20} (Permalloy: Py) deposits, elaborated by electrochemical process onto silicon nanowires (SiNWs). The morphology of SiNWs and Py/SiNWs were performed with scanning electron microscopy (SEM). The SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. The analysis of X-ray diffraction spectra shows a change in the texture with the deposition potential. The grain size, the lattice parameter and the strain were studied as a function of the deposition potentials. From hysteresis loops, we have shown that the magnetization easy axis is the plane of the samples. - Highlights: • Permalloy deposits were elaborated by electrochemical process onto silicon nanowires (SiNWs). • SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. • The magnetization easy axis was found to be in the plane of samples.

  9. 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)

  10. High Throughput Nanofabrication of Silicon Nanowire and Carbon Nanotube Tips on AFM Probes by Stencil-Deposited Catalysts

    DEFF Research Database (Denmark)

    Engstrøm, Daniel Southcott; Savu, Veronica; Zhu, Xueni

    2011-01-01

    A new and versatile technique for the wafer scale nanofabrication of silicon nanowire (SiNW) and multiwalled carbon nanotube (MWNT) tips on atomic force microscope (AFM) probes is presented. Catalyst material for the SiNW and MWNT growth was deposited on prefabricated AFM probes using aligned wafer...

  11. Stem-loop DNA-assisted silicon nanowires-based biochemical sensors with ultra-high sensitivity, specificity, and multiplexing capability

    Science.gov (United States)

    Xie, Juan; Jiang, Xiangxu; Zhong, Yiling; Lu, Yimei; Wang, Siyi; Wei, Xinpan; Su, Yuanyuan; He, Yao

    2014-07-01

    A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications.A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01097c

  12. 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

    2017-07-14

    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.

  13. Low-temperature vapour-liquid-solid (VLS) growth of vertically aligned silicon oxide nanowires using concurrent ion bombardment

    Science.gov (United States)

    Bettge, Martin; MacLaren, Scott; Burdin, Steve; Wen, Jian-Guo; Abraham, Daniel; Petrov, Ivan; Sammann, Ernie

    2009-03-01

    Vertically aligned silicon oxide nanowires can be synthesized over a large area by a low-temperature, ion-enhanced, reactive vapour-liquid-solid (VLS) method. Synthesis of these randomly ordered arrays begins with a thin indium film deposited on a Si or SiO2 surface. At the processing temperature of 190 °C, the indium film becomes a self-organized seed layer of molten droplets, receiving atomic silicon from a DC magnetron sputtering source rather than from the gaseous precursors used in conventional VLS growth. Simultaneous vigorous ion bombardment aligns the objects vertically and expedites mixing of oxygen and silicon into the indium. Silicon oxide precipitates from each droplet in the form of multiple thin strands having diameters as small as 5 nm. These strands form a single loose bundle growing normal to the surface, eventually consolidating to form one nanowire. The vertical rate of growth can reach 300 nm min-1 in an environment containing argon, hydrogen, and traces of water vapour. This paper discusses the physical and chemical factors leading to the formation of the nanostructures. It also demonstrates how the shape of the resulting nanostructures can be further controlled by sputtering, during both VLS growth and post-VLS processing. Key technological advantages of the developed process are nanowire growth at low substrate temperatures and the ability to form aligned nanostructure arrays, without the use of lithography or templates, on any substrate onto which a thin silicon film can be deposited.

  14. One-dimensional hole gas in germanium/silicon nanowire heterostructures

    Science.gov (United States)

    Lu, Wei; Xiang, Jie; Timko, Brian P.; Wu, Yue; Lieber, Charles M.

    2005-07-01

    Two-dimensional electron and hole gas systems, enabled through band structure design and epitaxial growth on planar substrates, have served as key platforms for fundamental condensed matter research and high-performance devices. The analogous development of one-dimensional (1D) electron or hole gas systems through controlled growth on 1D nanostructure substrates, which could open up opportunities beyond existing carbon nanotube and nanowire systems, has not been realized. Here, we report the synthesis and transport studies of a 1D hole gas system based on a free-standing germanium/silicon (Ge/Si) core/shell nanowire heterostructure. Room temperature electrical transport measurements clearly show hole accumulation in undoped Ge/Si nanowire heterostructures, in contrast to control experiments on single-component nanowires. Low-temperature studies show well-controlled Coulomb blockade oscillations when the Si shell serves as a tunnel barrier to the hole gas in the Ge channel. Transparent contacts to the hole gas also have been reproducibly achieved by thermal annealing. In such devices, we observe conductance quantization at low temperatures, corresponding to ballistic transport through 1D subbands, where the measured subband energy spacings agree with calculations for a cylindrical confinement potential. In addition, we observe a “0.7 structure,” which has been attributed to spontaneous spin polarization, suggesting the universality of this phenomenon in interacting 1D systems. Lastly, the conductance exhibits little temperature dependence, consistent with our calculation of reduced backscattering in this 1D system, and suggests that transport is ballistic even at room temperature. Author contributions: W.L., J.X., and C.M.L. designed research; W.L. and J.X. performed research; B.P.T. and Y.W. contributed new reagents/analytic tools; W.L., J.X., and C.M.L. analyzed data; W.L., J.X., and C.M.L. wrote the paper; and B.P.T. and Y.W. developed growth of nanowire

  15. 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

  16. 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

  17. Influence of Cu as a catalyst on the properties of silicon nanowires synthesized by the vapour-solid-solid mechanism

    International Nuclear Information System (INIS)

    Arbiol, Jordi; Kalache, Billel; Cabarrocas, Pere Roca i; Morante, Joan Ramon; Morral, Anna Fontcuberta i

    2007-01-01

    Unlike typical Au used as a catalyst for the synthesis of silicon nanowires via the vapour-liquid-solid mechanism, Cu has been found to induce a synthesis process governed by the vapour-solid-solid mechanism. Moreover, the temperature window for obtaining high-quality wires with Cu has been found to be relatively smaller than that shown by the Au: from 600 to 650 deg. C. However, high-resolution transmission electron microscopy analysis reveals significant new properties of the nanowires obtained. They have the peculiarity of successively switching the silicon structure from diamond to the wurtzite phase along the growth direction. This change of the crystalline structure implies that it has an important impact on the transport properties and characteristics of electronic devices. The results will be important for the future integration and application of silicon, where electrical and thermal transport properties play a significant role

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

    Science.gov (United States)

    Li, Kuntang; Wang, Xiuqin; Lu, Pengfei; Ding, Jianning; Yuan, Ningyi

    2013-09-23

    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.

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Luo Guanghong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Diao Jiajie [Department of Physics, George Washington University, Washington, DC 20052 (United States); Chornoguz, Olesya [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Reeves, Mark [Department of Physics, George Washington University, Washington, DC 20052 (United States); Vertes, Akos [Department of Chemistry, George Washington University, Washington, DC 20052 (United States)

    2007-04-15

    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 3x{omega} Nd:YAG laser in air, SF{sub 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 {approx}2 {mu}m in SF{sub 6} gas and to {approx}5 {mu}m 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 ({approx}10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits.

  1. Improvement of carrier diffusion length in silicon nanowire arrays using atomic layer deposition

    Science.gov (United States)

    Kato, Shinya; Kurokawa, Yasuyoshi; Miyajima, Shinsuke; Watanabe, Yuya; Yamada, Akira; Ohta, Yoshimi; Niwa, Yusuke; Hirota, Masaki

    2013-08-01

    To achieve a high-efficiency silicon nanowire (SiNW) solar cell, surface passivation technique is very important because a SiNW array has a large surface area. We successfully prepared by atomic layer deposition (ALD) high-quality aluminum oxide (Al2O3) film for passivation on the whole surface of the SiNW arrays. The minority carrier lifetime of the Al2O3-depositedSiNW arrays with bulk silicon substrate was improved to 27 μs at the optimum annealing condition. To remove the effect of bulk silicon, the effective diffusion length of minority carriers in the SiNW array was estimated by simple equations and a device simulator. As a result, it was revealed that the effective diffusion length in the SiNW arrays increased from 3.25 to 13.5 μm by depositing Al2O3 and post-annealing at 400°C. This improvement of the diffusion length is very important for application to solar cells, and Al2O3 deposited by ALD is a promising passivation material for a structure with high aspect ratio such as SiNW arrays.

  2. 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.

  3. 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.

  4. Localized Electrothermal Annealing with Nanowatt Power for a Silicon Nanowire Field-Effect Transistor.

    Science.gov (United States)

    Park, Jun-Young; Lee, Byung-Hyun; Lee, Geon-Beom; Bae, Hagyoul; Choi, Yang-Kyu

    2018-02-07

    This work investigates localized electrothermal annealing (ETA) with extremely low power consumption. The proposed method utilizes, for the first time, tunneling-current-induced Joule heat in a p-i-n diode, consisting of p-type, intrinsic, and n-type semiconductors. The consumed power used for dopant control is the lowest value ever reported. A metal-oxide-semiconductor field-effect transistor (MOSFET) composed of a p-i-n silicon nanowire, which is a substructure of a tunneling FET (TFET), was fabricated and utilized as a test platform to examine the annealing behaviors. A more than 2-fold increase in the on-state (I ON ) current was achieved using the ETA. Simulations are conducted to investigate the location of the hot spot and how its change in heat profile activates the dopants.

  5. Lithiation Behavior of Silicon Nanowire Anodes for Lithium-Ion Batteries: Impact of Functionalization and Porosity.

    Science.gov (United States)

    Schmerling, Marcus; Fenske, Daniela; Peters, Fabian; Schwenzel, Julian; Busse, Matthias

    2018-01-05

    Metal-assisted chemical etching (MACE) provides a versatile way to synthesize silicon nanowires (SiNW) of different morphologies. MACE was used to synthesize oxide-free porous and nonporous SiNW for use as anodes for lithium-ion batteries. To improve their processing behavior, the SiNW were functionalized using acrylic acid. Differential capacity plots were used as a way to identify the degradation processes during cycling through tracking the formation of Li 15 Si 4 and changes in polarization. The cycling performance between porous and nonporous SiNW differed regarding Coulombic efficiency and cycling stability. The differences were attributed to the porous hull and its ability to reduce the volume expansion, although not through its porous nature but the reduced uptake of Li ions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Catalytic Activity of Silicon Nanowires Decorated with Gold and Copper Nanoparticles Deposited by Pulsed Laser Ablation

    Directory of Open Access Journals (Sweden)

    Michele Casiello

    2018-01-01

    Full Text Available Silicon nanowires (SiNWs decorated by pulsed laser ablation with gold or copper nanoparticles (labeled as AuNPs@SiNWs and CuNPs@SiNWs were investigated for their catalytic properties. Results demonstrated high catalytic performances in the Caryl–N couplings and subsequent carbonylations for gold and copper catalysts, respectively, that have no precedents in the literature. The excellent activity, attested by the very high turn over number (TON values, was due both to the uniform coverage along the NW length and to the absence of the chemical shell surrounding the metal nanoparticles (MeNPs. A high recyclability was also observed and can be ascribed to the strong covalent interaction at the Me–Si interface by virtue of metal “silicides” formation.

  7. Performance of Silicon Nanowire Solar Cells with Phosphorus-Diffused Emitters

    Directory of Open Access Journals (Sweden)

    Lingsheng Zeng

    2012-01-01

    Full Text Available Vertical silicon nanowire (Si NW arrays on a Si (100 substrate have been prepared by using a low-cost and facile Ag-assisted chemical etching technique. The reflectance of Si NW arrays is very low (<1% in the spectral range from 400 to 1000 nm. By phosphorus diffusion into Si NW arrays to fabricate solar cells, the power conversion efficiency of 8.84% has been achieved. This power conversion efficiency is much higher than that of the planar cell with the similar celling technology. It is found that the efficiency of Si NW solar cells is intimately associated with their excellent antireflection property. The surface recombination of Si NWs is the main obstacle for the improvement of solar cell efficiency. The current results are helpful to the advancement of the application of Si NWs in photovoltaics.

  8. Enhanced vapour sensing using silicon nanowire devices coated with Pt nanoparticle functionalized porous organic frameworks

    KAUST Repository

    Cao, Anping

    2018-03-09

    Recently various porous organic frameworks (POFs, crystalline or amorphous materials) have been discovered, and used for a wide range of applications, including molecular separations and catalysis. Silicon nanowires (SiNWs) have been extensively studied for diverse applications, including as transistors, solar cells, lithium ion batteries and sensors. Here we demonstrate the functionalization of SiNW surfaces with POFs and explore its effect on the electrical sensing properties of SiNW-based devices. The surface modification by POFs was easily achieved by polycondensation on amine-modified SiNWs. Platinum nanoparticles were formed in these POFs by impregnation with chloroplatinic acid followed by chemical reduction. The final hybrid system showed highly enhanced sensitivity for methanol vapour detection. We envisage that the integration of SiNWs with POF selector layers, loaded with different metal nanoparticles will open up new avenues, not only in chemical and biosensing, but also in separations and catalysis.

  9. 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.

  10. Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

    Science.gov (United States)

    Wu, Jiayang; Moein, Tania; Xu, Xingyuan; Moss, David J.

    2018-04-01

    We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

  11. Nanowire Field-Effect Transistors : Sensing Simplicity?

    NARCIS (Netherlands)

    Mescher, M.

    2014-01-01

    Silicon nanowires are structures made from silicon with at least one spatial dimension in the nanometer regime (1-100 nm). From these nanowires, silicon nanowire field-effect transistors can be constructed. Since their introduction in 2001 silicon nanowire field-effect transistors have been studied

  12. Ultrasensitive chemiluminescence biosensors using nucleic acid-functionalized silver-cysteine nanowires as signal amplifying labels.

    Science.gov (United States)

    Chen, Wenjuan; Chen, Yuan; Wang, Meilan; Chi, Yuwu

    2018-03-26

    Ultrasensitive chemiluminescence (CL) sensors for biomolecules (DNA and proteins) have been developed by adopting DNA-functionalized silver-cysteine hybrid nanowires (p-SCNWs) as signal amplifying labels. The sensing is established from a sandwich-type DNA hybridization, where the target DNA strands are initially hybridized with the capture DNA located at paramagnetic microspheres (PMs) and subsequently hybridized with p-SCNWs functionalized with the signal DNA probe. After magnetic separation, p-SCNWs on the hybrids were completely decomposed with HNO3 to release numerous silver ions. The powerful catalysis of silver ions toward the redox reaction of K2S2O8-Mn2+-H3PO4 causes the generation of KMnO4 that is capable of oxidizing luminol at high pH, triggering an amplified chemiluminescent signal emission. The sensing combines the extraordinary sensitivity of the catalytic chemiluminescence technology and the amplifying strategy via releasing large quantities of silver ions as the catalyst from each hybrid, enabling the assay of target DNA strands at a concentration as low as 0.34 fM. The CL signals associated with single-base pair mismatched DNA strands and non-complementary DNA strands are able to be discriminated well from the CL signal related to the complementary DNA hybridization. Likewise, the combination of p-SCNWs functionalized with an aptamer and PMs/aptamer/thrombin complex allowed the chemiluminescence sensing of thrombin with a low limit of detection corresponding to 0.17 pM.

  13. 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)

  14. 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)

  15. 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.

  16. Analysis of Chemical Bonding and Structural Network of Gold Silicide in Core-Shell Silicon Nanowire

    Science.gov (United States)

    Swain, Bibhu P.; Swain, Bhabani S.

    2018-02-01

    The Au-catalyzed core-shell silicon nanowires (Si-NWs) were synthesized by chemical vapor deposition by using SiH4 and H2 precursor gases. The TEM and FTIR studies revealed that the Si-NWs consist of core silicon surrounded by a thick oxide sheath and Au distributed at the a-SiOx/Si interface. The x-ray photoelectron spectroscopy (XPS) was used to study the chemical composition and electronic environments of gold silicide in the a-SiO x /Si-NWs. The elemental analysis and chemical network of gold silicide of core-shell Si-NWs were explained on the basis of the random atomic distribution of Si, O and Au atoms. The Raman spectra and XRD peak reveal the crystalline core of Si-NWs. The individual contribution to the Au (4d) core orbital was deconvoluted to Au-Si-Au, Au-Si-O, Au-Au, Au-O-Au, Au-O-Si and Au=O/Au-O2 bonding structure. The analysis shows that the O linked with Si and Au has also contributed to growth of Si-NWs.

  17. Oxide-free hybrid silicon nanowires: From fundamentals to applied nanotechnology

    Science.gov (United States)

    Bashouti, Muhammad Y.; Sardashti, Kasra; Schmitt, Sebastian W.; Pietsch, Matthias; Ristein, Jürgen; Haick, Hossam; Christiansen, Silke H.

    2013-02-01

    The ability to control physical properties of silicon nanowires (Si NWs) by designing their surface bonds is important for their applicability in devices in the areas of nano-electronics, nano-photonics, including photovoltaics and sensing. In principle a wealth of different molecules can be attached to the bare Si NW surface atoms to create e.g. Si-O, Si-C, Si-N, etc. to mention just the most prominent ones. Si-O bond formation, i.e. oxidation usually takes place automatically as soon as Si NWs are exposed to ambient conditions and this is undesired is since a defective oxide layer (i.e. native silicon dioxide - SiO2) can cause uncontrolled trap states in the band gap of silicon. Surface functionalization of Si NW surfaces with the aim to avoid oxidation can be carried out by permitting e.g. Si-C bond formation when alkyl chains are covalently attached to the Si NW surfaces by employing a versatile two-step chlorination/alkylation process that does not affect the original length and diameter of the NWs. Termination of Si NWs with alkyl molecules through covalent Si-C bonds can provide long term stability against oxidation of the Si NW surfaces. The alkyl chain length determines the molecular coverage of Si NW surfaces and thus the surface energy and next to simple Si-C bonds even bond types such as Cdbnd C and Ctbnd C can be realized. When integrating differently functionalized Si NWs in functional devices such as field effect transistors (FETs) and solar cells, the physical properties of the resultant devices vary.

  18. Label-free biosensor array based on silicon-on-insulator ring resonators addressed using a WDM approach.

    Science.gov (United States)

    Xu, D-X; Vachon, M; Densmore, A; Ma, R; Delâge, A; Janz, S; Lapointe, J; Li, Y; Lopinski, G; Zhang, D; Liu, Q Y; Cheben, P; Schmid, J H

    2010-08-15

    We report a silicon-on-insulator ring resonator biosensor array with one output port, using wavelength division multiplexing as the addressing scheme. With the use of on-chip referencing for environmental drift cancellation, simultaneous monitoring of multiplexed molecular bindings is demonstrated, with a resolution of 0.3 pg/mm(2) (40 ag of total mass) for protein concentrations over 4 orders of magnitude down to 20 pM. Reactions are measured over time periods as long as 3 h with high stability.

  19. 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.

  20. Selective sodium sensing with gold-coated silicon nanowire field-effect transistors in a differential setup.

    Science.gov (United States)

    Wipf, Mathias; Stoop, Ralph L; Tarasov, Alexey; Bedner, Kristine; Fu, Wangyang; Wright, Iain A; Martin, Colin J; Constable, Edwin C; Calame, Michel; Schönenberger, Christian

    2013-07-23

    Ion-sensitive field-effect transistors based on silicon nanowires with high dielectric constant gate oxide layers (e.g., Al2O3 or HfO2) display hydroxyl groups which are known to be sensitive to pH variations but also to other ions present in the electrolyte at high concentration. This intrinsically nonselective sensitivity of the oxide surface greatly complicates the selective sensing of ionic species other than protons. Here, we modify individual nanowires with thin gold films as a novel approach to surface functionalization for the detection of specific analytes. We demonstrate sodium ion (Na(+)) sensing by a self-assembled monolayer (SAM) of thiol-modified crown ethers in a differential measurement setup. A selective Na(+) response of ≈-44 mV per decade in a NaCl solution is achieved and tested in the presence of protons (H(+)), potassium (K(+)), and chloride (Cl(-)) ions, by measuring the difference between a nanowire with a gold surface functionalized by the SAM (active) and a nanowire with a bare gold surface (control). We find that the functional SAM does not affect the unspecific response of gold to pH and background ionic species. This represents a clear advantage of gold compared to oxide surfaces and makes it an ideal candidate for differential measurements.

  1. Multi-Wire Tri-Gate Silicon Nanowires Reaching Milli-pH Unit Resolution in One Micron Square Footprint

    Directory of Open Access Journals (Sweden)

    Enrico Accastelli

    2016-03-01

    Full Text Available The signal-to-noise ratio of planar ISFET pH sensors deteriorates when reducing the area occupied by the device, thus hampering the scalability of on-chip analytical systems which detect the DNA polymerase through pH measurements. Top-down nano-sized tri-gate transistors, such as silicon nanowires, are designed for high performance solid-state circuits thanks to their superior properties of voltage-to-current transduction, which can be advantageously exploited for pH sensing. A systematic study is carried out on rectangular-shaped nanowires developed in a complementary metal-oxide-semiconductor (CMOS-compatible technology, showing that reducing the width of the devices below a few hundreds of nanometers leads to higher charge sensitivity. Moreover, devices composed of several wires in parallel further increase the exposed surface per unit footprint area, thus maximizing the signal-to-noise ratio. This technology allows a sub milli-pH unit resolution with a sensor footprint of about 1 µm2, exceeding the performance of previously reported studies on silicon nanowires by two orders of magnitude.

  2. 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.

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

    International Nuclear Information System (INIS)

    Fellahi, Ouarda; Barras, Alexandre; Pan, Guo-Hui; Coffinier, Yannick; Hadjersi, Toufik; Maamache, Mustapha; Szunerits, Sabine

    2016-01-01

    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 2 Cr 2 O 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 3 aqueous solution. The Cu NPs were deposited on SiNW arrays via electroless deposition technique. Visible light irradiation of an aqueous solution of K 2 Cr 2 O 7 (10 −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.

  4. GaAs-AlGaAs core-shell nanowire lasers on silicon: invited review

    Science.gov (United States)

    Koblmüller, Gregor; Mayer, Benedikt; Stettner, Thomas; Abstreiter, Gerhard; Finley, Jonathan J.

    2017-05-01

    Semiconductor nanowire (NW) lasers provide significant potential to create a new generation of lasers and on-chip coherent light sources by virtue of their ability to operate as single mode optical waveguides at the nanoscale. Due to their unique geometry, a major benefit lies also in the feasibility for direct integration on silicon (Si), enabling III-V-on-Si NW lasers that could fuel applications in optical interconnects and data communication. In this review, we describe the state-of-the-art and recent progress in GaAs-AlGaAs based NW lasers emitting in the near infrared (NIR) spectral region, with a specific emphasis on integration on a Si platform. First, we explore design rules for the photonic properties in GaAs NW waveguides based on finite difference time domain calculations. The lasing characteristics of GaAs-AlGaAs core-shell NW lasers are then investigated under various different optical pumping schemes ranging from pulsed to continuous wave excitation. We further review recent activities on the realization of low-dimensional quantum heterostructures inside NW cavities as a means to tune lasing wavelength, gain and threshold properties. Ultimately, we describe schemes for monolithic integration of GaAs-based NW lasers directly on Si and show how such vertical nanocavity lasers are excellent candidates for low-threshold lasing, high spontaneous emission coupling (high β-factor lasers), and ultrafast emission characteristics.

  5. Pulmonary Toxicity, Distribution, and Clearance of Intratracheally Instilled Silicon Nanowires in Rats

    Directory of Open Access Journals (Sweden)

    Jenny R. Roberts

    2012-01-01

    Full Text Available Silicon nanowires (Si NWs are being manufactured for use as sensors and transistors for circuit applications. The goal was to assess pulmonary toxicity and fate of Si NW using an in vivo experimental model. Male Sprague-Dawley rats were intratracheally instilled with 10, 25, 50, 100, or 250 μg of Si NW (~20–30 nm diameter; ~2–15 μm length. Lung damage and the pulmonary distribution and clearance of Si NW were assessed at 1, 3, 7, 28, and 91 days after-treatment. Si NW treatment resulted in dose-dependent increases in lung injury and inflammation that resolved over time. At day 91 after treatment with the highest doses, lung collagen was increased. Approximately 70% of deposited Si NW was cleared by 28 days with most of the Si NW localized exclusively in macrophages. In conclusion, Si NW induced transient lung toxicity which may be associated with an early rapid particle clearance; however, persistence of Si NW over time related to dose or wire length may lead to increased collagen deposition in the lung.

  6. Electrical spin transport in cylindrical silicon nanowires with CoFeB/MgO contacts

    Science.gov (United States)

    Park, Tae-Eon; Min, Byoung-Chul; Park, Hee Gyum; Lee, Jaejun; Jo, Moon-Ho; Jang, Chaun; Koo, Hyun Cheol; Choi, Heon-Jin; Chang, Joonyeon

    2017-08-01

    We examined electrical spin transport in cylindrical silicon nanowires (Si NWs) using the lateral nonlocal spin-valve (NLSV) geometry with CoFeB/MgO contacts. The use of a thin MgO layer as the tunnel barrier in the NLSV devices provided an optimum resistance-area product for spin transport measurements in the Si NWs. A robust NLSV spin signal of over 3.95 kΩ and clear minor loops were observed at 1.8 K in the Si NWs heavily doped with phosphorous. Furthermore, the NLSV magnetoresistance was strongly influenced by the local magnetizations resulting from the ferromagnetic (FM) electrodes being attached to the cylindrically shaped Si NW, with these magnetizations differing from those of bulk ferromagnets. These local micro-magnetic configurations of the FM electrodes led to intriguing NLSV spin signals associated with the Hanle effect. Our study of spin transport in the heavily doped Si NWs provides a sound basis for developing applications of nanoscale semiconductor spintronic devices.

  7. Supercontinuum generation in silicon nanowire embedded photonic crystal fibers with different core geometries

    Science.gov (United States)

    Abdosllam, M. Abobaker; Gunasundari, E.; Senthilnathan, K.; Sivabalan, S.; Nakkeeran, K.; Ramesh Babu, P.

    2014-07-01

    We design various silicon nanowire embedded photonic crystal fibers (SN-PCFs) with different core geometries, namely, circular, rectangular and elliptical using finite element method. Further, we study the optical properties such as group velocity dispersion (GVD), third order dispersion (TOD) of x and y-polarized modes and effective nonlinearity for a wavelength range from 0.8 to 1.6 μm. The proposed structure exhibits almost flat GVD (0.8 to 1.2 μm wavelength), zero GVD (≍ 1.31 μm) and small TOD (0.00069 ps3/m) at 1.1 μm wavelength and high nonlinearity (2916 W-1m-1) at 0.8 μm wavelength for a 300 nm core diameter of circular core SN-PCF. Besides, we have been able to demonstrate the supercontinuum for the different core geometries at 1.3 μm wavelength with a less input power of 25 W for the input pulse of 20 fs. The numerical simulation results reveal that the proposed circular core SN-PCF could generate the supercontinuum of wider bandwidth (900 nm) compared to that from rest of the geometries. This enhanced bandwidth turns out to be a boon for optical coherence tomography (OCT) system.

  8. 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)

  9. Multiple silicon nanowire complementary tunnel transistors for ultralow-power flexible logic applications

    Science.gov (United States)

    Lee, M.; Jeon, Y.; Jung, J.-C.; Koo, S.-M.; Kim, S.

    2012-06-01

    Based on experimental and simulation studies to gain insight into the suppression of ambipolar conduction in two distinct tunnel field-effect transistor (TFET) devices (that is, an asymmetric source-drain doping or a properly designed gate underlap), here we report on the fabrication and electrical/mechanical characterization of a flexible complementary TFET (c-TFET) inverter on a plastic substrate using multiple silicon nanowires (SiNWs) as the channel material. The static voltage transfer characteristic of the SiNW c-TFET inverter exhibits a full output voltage swing between 0 V and Vdd with a high voltage gain of ˜29 and a sharp transition of 0.28 V at Vdd = 3 V. A leakage power consumption of the SiNW c-TFET inverter in the standby state is as low as 17.1 pW for Vdd = 3 V. Moreover, its mechanical bendability indicates that it has good fatigue properties, providing an important step towards the realization of ultralow-power flexible logic circuits.

  10. Carrier density distribution in silicon nanowires investigated by scanning thermal microscopy and Kelvin probe force microscopy.

    Science.gov (United States)

    Wielgoszewski, Grzegorz; Pałetko, Piotr; Tomaszewski, Daniel; Zaborowski, Michał; Jóźwiak, Grzegorz; Kopiec, Daniel; Gotszalk, Teodor; Grabiec, Piotr

    2015-12-01

    The use of scanning thermal microscopy (SThM) and Kelvin probe force microscopy (KPFM) to investigate silicon nanowires (SiNWs) is presented. SThM allows imaging of temperature distribution at the nanoscale, while KPFM images the potential distribution with AFM-related ultra-high spatial resolution. Both techniques are therefore suitable for imaging the resistance distribution. We show results of experimental examination of dual channel n-type SiNWs with channel width of 100 nm, while the channel was open and current was flowing through the SiNW. To investigate the carrier distribution in the SiNWs we performed SThM and KPFM scans. The SThM results showed non-symmetrical temperature distribution along the SiNWs with temperature maximum shifted towards the contact of higher potential. These results corresponded to those expressed by the distribution of potential gradient along the SiNWs, obtained using the KPFM method. Consequently, non-uniform distribution of resistance was shown, being a result of non-uniform carrier density distribution in the structure and showing the pinch-off effect. Last but not least, the results were also compared with results of finite-element method modeling. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. A Novel Method to Grow Vertically Aligned Silicon Nanowires on Si (111 and Their Optical Absorption

    Directory of Open Access Journals (Sweden)

    Tzuen-Wei Ho

    2012-01-01

    Full Text Available In this study we grew silicon nanowires (SiNWs on Si (111 substrate by gold-catalyzed vapor liquid solid (VLS process using tetrachlorosilane (SiCl4 in a hot-wall chemical vapor deposition reactor. SiNWs with 150–200 nm diameters were found to grow along the orientations of all 〈111〉 family, including the vertical and the inclined, on Si (111. The effects of various process conditions, including SiCl4 concentration, SiCl4 feeding temperature, H2 annealing, and ramp cooling, on the crystal quality and growth orientation of SiNWs, were studied to optimize the growth conditions. Furthermore, a novel method was developed to reliably grow vertically aligned SiNWs on Si (111 utilizing the principle of liquid phase epitaxy (LPE. A ramp-cooling process was employed to slowly precipitate the epitaxial Si seeds on Si (111 after H2 annealing at 650°C. Then, after heating in SiCl4/H2 up to 850°C to grow SiNWs, almost 100% vertically aligned SiNWs could be achieved reproducibly. The high degree of vertical alignment of SiNWs is effective in reducing surface reflection of solar light with the reflectance decreasing with increasing the SiNWs length. The vertically aligned SiNWs have good potentials for solar cells and nano devices.

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

    Science.gov (United States)

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

    2017-10-01

    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.

  13. Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect

    KAUST Repository

    Zhang, Qianfan

    2011-05-19

    Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographic directions. Due to distinct atomic configuration and electronic structure of SiNWs with different axial orientations, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, including binding energy, diffusion barriers, and dependence on uniaxial strain in [110], [100], [111], and [112] SiNWs. Our systematic ab initio study suggests that the Si-Li interaction is weaker when the Si-Li bond direction is aligned close to the SiNW long axis. This results in the [110] and [111] SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusion barrier along the SiNW axis lower than other pathways. Under external strain, it was found that [110] and [001] SiNWs are the most and least sensitive, respectively. For diffusion along the axial direction, the barrier increases (decreases) under tension (compression). This feature results in a considerable difference in the magnitude of the energy barrier along different diffusion pathways. © 2011 American Chemical Society.

  14. 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.

  15. 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.

  16. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively.

    Science.gov (United States)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-04-25

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50-15000 μmoL L(-1) (cubic SiC NWs) and 5-8000 μmoL L(-1) (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L(-1) respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility.

  17. Graphene encapsulated and SiC reinforced silicon nanowires as an anode material for lithium ion batteries.

    Science.gov (United States)

    Yang, Yang; Ren, Jian-Guo; Wang, Xin; Chui, Ying-San; Wu, Qi-Hui; Chen, Xianfeng; Zhang, Wenjun

    2013-09-21

    Anode materials play a key role in the performance, in particular the capacity and lifetime, of lithium ion batteries (LIBs). Silicon has been demonstrated to be a promising anode material due to its high specific capacity, but pulverization during cycling and formation of an unstable solid-electrolyte interphase limit its cycle life. Herein, we show that anodes consisting of an active silicon nanowire (Si NW), which is surrounded by a uniform graphene shell and comprises silicon carbide nanocrystals, are capable of serving over 500 cycles in half cells at a high lithium storage capacity of 1650 mA h g(-1). In the anodes, the graphene shell provides a highly-conductive path and prevents direct exposure of Si NWs to electrolytes while the SiC nanocrystals may act as a rigid backbone to retain the integrity of the Si NW in its great deformation process caused by repetitive charging-discharging reactions, resulting in a stable cyclability.

  18. Development of silicon photonic microring resonator biosensors for multiplexed cytokine assays and in vitro diagnostics

    Science.gov (United States)

    Luchansky, Matthew Sam

    In order to guide critical care therapies that are personalized to a patient's unique disease state, a diagnostic or theranostic medical device must quickly provide a detailed biomolecular understanding of disease onset and progression. This detailed molecular understanding of cellular processes and pathways requires the ability to measure multiple analytes in parallel. Though many traditional sensing technologies for biomarker analysis and fundamental biological studies (i.e. enzyme-linked immunosorbent assays, real-time polymerase chain reaction, etc.) rely on single-parameter measurements, it has become increasingly clear that the inherent complexity of many human illnesses and pathways necessitates quantitative and multiparameter analysis of biological samples. Currently used analytical methods are deficient in that they often provide either highly quantitative data for a single biomarker or qualitative data for many targets, but methods that simultaneously provide highly quantitative analysis of many targets have yet to be adequately developed. Fields such as medical diagnostics and cellular biology would benefit greatly from a technology that enables rapid, quantitative and reproducible assays for many targets within a single sample. In an effort to fill this unmet need, this doctoral dissertation describes the development of a clinically translational biosensing technology based on silicon photonics and developed in the chemistry research laboratory of Ryan C. Bailey. Silicon photonic microring resonators, a class of high-Q optical sensors, represent a promising platform for rapid, multiparameter in vitro measurements. The original device design utilizes 32-ring arrays for real-time biomolecular sensing without fluorescent labels, and these optical biosensors display great potential for more highly multiplexed (100s-1000s) measurements based on the impressive scalability of silicon device fabrication. Though this technology can be used to detect a variety of

  19. 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.

  20. Non-Degenerate Four-Wave Mixing in a Silicon Nanowire and its Application for One-to-Six WDM Multicasting

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2011-01-01

    We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements.......We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements....

  1. Fabrication of silicon nanowire/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-graphene oxide hybrid solar cells

    Science.gov (United States)

    Uma, Kasimayan; Subramani, Thiyagu; Syu, Hong-Jhang; Lin, Tzu-Ching; Lin, Ching-Fuh

    2015-03-01

    Silicon nanowire (SiNW)/Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) Schottky junctions have shown great promise as high efficiency, cost effective solar cells. Here, hybrid SiNWs/PEDOT:PSS blended graphene oxide (GO) solar cells are prepared and investigated. The SiNWs/PEDOT:PSS blended GO cells show enhanced light trapping and a large junction area when compared to pure PEDOT:PSS structures. SiNWs combined with GO solar cells show energy conversion efficiencies of up to 9.57% under the AM 1.5G condition, opening the possibility of using semiconductor/graphene oxide in photovoltaic applications.

  2. Nanoampere charge pump by single-electron ratchet using silicon nanowire metal-oxide-semiconductor field-effect transistor

    Science.gov (United States)

    Fujiwara, Akira; Nishiguchi, Katsuhiko; Ono, Yukinori

    2008-01-01

    Nanoampere single-electron pumping is presented at 20K using a single-electron ratchet comprising silicon nanowire metal-oxide-semiconductor field-effect transistors. The ratchet features an asymmetric potential with a pocket that captures single electrons from the source and ejects them to the drain. Directional single-electron transfer is achieved by applying one ac signal with the frequency up to 2.3GHz. We find anomalous shapes of current steps which can be ascribed to nonadiabatic electron capture.

  3. Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires.

    Science.gov (United States)

    Chong, Su Kong; Dee, Chang Fu; Abdul Rahman, Saadah

    2013-04-17

    Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO.

  4. High aspect ratio silicon nanowires control fibroblast adhesion and cytoskeleton organization

    Science.gov (United States)

    Andolfi, Laura; Murello, Anna; Cassese, Damiano; Ban, Jelena; Dal Zilio, Simone; Lazzarino, Marco

    2017-04-01

    Cell-cell and cell-matrix interactions are essential to the survival and proliferation of most cells, and are responsible for triggering a wide range of biochemical pathways. More recently, the biomechanical role of those interactions was highlighted, showing, for instance, that adhesion forces are essential for cytoskeleton organization. Silicon nanowires (Si NWs) with their small size, high aspect ratio and anisotropic mechanical response represent a useful model to investigate the forces involved in the adhesion processes and their role in cellular development. In this work we explored and quantified, by single cell force spectroscopy (SCFS), the interaction of mouse embryonic fibroblasts with a flexible forest of Si NWs. We observed that the cell adhesion forces are comparable to those found on collagen and bare glass coverslip, analogously the membrane tether extraction forces are similar to that on collagen but stronger than that on bare flat glass. Cell survival did not depend significantly on the substrate, although a reduced proliferation after 36 h was observed. On the contrary both cell morphology and cytoskeleton organization revealed striking differences. The cell morphology on Si-NW was characterized by a large number of filopodia and a significant decrease of the cell mobility. The cytoskeleton organization was characterized by the absence of actin fibers, which were instead dominant on collagen and flat glass support. Such findings suggest that the mechanical properties of disordered Si NWs, and in particular their strong asymmetry, play a major role in the adhesion, morphology and cytoskeleton organization processes. Indeed, while adhesion measurements by SCFS provide out-of-plane forces values consistent with those measured on conventional substrates, weaker in-plane forces hinder proper cytoskeleton organization and migration processes.

  5. Influence of the polymer matrix on the efficiency of hybrid solar cells based on silicon nanowires

    International Nuclear Information System (INIS)

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

    2012-01-01

    Highlights: ► Hybrid solar cells based on silicon nanowires have been fabricated. ► The relation between the morphology of the composite thin films and the charge transfer between the polymer matrices and SiNWs has been examined. ► We have investigated the effect of the polymer matrix on the photovoltaic characteristics. - Abstract: Poly (N-vinylcarbazole) (PVK):SiNWs and poly (2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenyl vinylene) (MEH-PPV):SiNWs bulk-heterojunctions (BHJ) have been elaborated from blends of SiNWs and the polymer in solution from a common solvent. Optical properties of these nanocomposites have been investigated by UV–vis absorption and photoluminescence (PL) spectral measurements. We have studied the charge transfer between SiNWs and the two polymers using the photoluminescence quenching of PVK and MEH-PPV which is a convenient signature of the reduced radiative recombination of the generated charge pairs upon exciton dissociation. We found that PVK and SiNWs constitutes the better donor–acceptor system. In order to understand the difference between PVK:SiNWs or MEH-PPV:SiNWs behaviours, photoluminescence responses were correlated with the topography (SEM) of the thin films. The photovoltaic effect of ITO/PEDOT:PSS/SiNWs:PVK/Al and ITO/PEDOT:PSS/SiNWs:MEH-PPV/Al structures was studied by current–voltage (I–V) measurements in dark and under illumination and interpreted on the basis of the charge transfer differences resulting from the morphologies.

  6. Influence of the polymer matrix on the efficiency of hybrid solar cells based on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ben Dkhil, S., E-mail: sadok.bendekhil@gmail.com [Laboratoire Physique des Materiaux: Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Ingenierie des Materiaux Polymeres: IMP, UMR CNRS 5223, Universite Claude Bernard Lyon 1, 15 boulevard Latarjet, 69622 Villeurbanne (France); Bourguiga, R. [Laboratoire Physique des Materiaux: Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Davenas, J. [Ingenierie des Materiaux Polymeres: IMP, UMR CNRS 5223, Universite Claude Bernard Lyon 1, 15 boulevard Latarjet, 69622 Villeurbanne (France); Cornu, D. [Institut Europeen des Membranes, UMR CNRS 5635, Ecole Nationale superieure de Chimie, Universite de Montpellier, 1919 route de Mende, 34000 Montpellier (France)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Hybrid solar cells based on silicon nanowires have been fabricated. Black-Right-Pointing-Pointer The relation between the morphology of the composite thin films and the charge transfer between the polymer matrices and SiNWs has been examined. Black-Right-Pointing-Pointer We have investigated the effect of the polymer matrix on the photovoltaic characteristics. - Abstract: Poly (N-vinylcarbazole) (PVK):SiNWs and poly (2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenyl vinylene) (MEH-PPV):SiNWs bulk-heterojunctions (BHJ) have been elaborated from blends of SiNWs and the polymer in solution from a common solvent. Optical properties of these nanocomposites have been investigated by UV-vis absorption and photoluminescence (PL) spectral measurements. We have studied the charge transfer between SiNWs and the two polymers using the photoluminescence quenching of PVK and MEH-PPV which is a convenient signature of the reduced radiative recombination of the generated charge pairs upon exciton dissociation. We found that PVK and SiNWs constitutes the better donor-acceptor system. In order to understand the difference between PVK:SiNWs or MEH-PPV:SiNWs behaviours, photoluminescence responses were correlated with the topography (SEM) of the thin films. The photovoltaic effect of ITO/PEDOT:PSS/SiNWs:PVK/Al and ITO/PEDOT:PSS/SiNWs:MEH-PPV/Al structures was studied by current-voltage (I-V) measurements in dark and under illumination and interpreted on the basis of the charge transfer differences resulting from the morphologies.

  7. Polymer-free Vertical Transfer of Silicon Nanowires and their Application to Energy Storage.

    Science.gov (United States)

    Kim, Han-Jung; Lee, Jihye; Lee, Sang Eon; Kim, Wanjung; Kim, Hwan Jin; Choi, Dae-Geun; Park, Jong Hyeok

    2013-11-01

    Silicon nanowires (SiNWs) for use as lithium-ion battery (LIB) anode materials have been studied for their one-dimensional (1D) properties and ability to accommodate large volume changes and avoid rapid capacity fading during cycling. Although the vertical transfer of SiNWs from their original substrate onto a conducting electrode is very important, to date, there has been no report of a direct integration method without polymer binders. Here, we propose for the first time a vertical transfer method for SiNWs grown on a Si substrate directly to the current-collecting electrode without using a polymer adhesive for the use as a binder-free LIB anode. The vertical SiNWs produced using a low-cost wafer-scale metal-assisted chemical etching (MaCE) process have been successfully transferred directly to a copper electrode coated with a thin Ag layer by using a simple hot pressing method. When evaluated as an LIB anode without using conventional polymeric binder and a conducting additive, the transferred vertically aligned SiNWs showed a high specific capacity (≈2150 mAh g(-1) ) and excellent rate performance. It is believed that the anode-manufacturing process is simple and fast, thus enabling a large-scale production that is of low-cost, broadly applicable, and provides new avenues for the rational engineering of Si-based electrode materials with enhanced power density and conductivity. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Surface potential variations on a silicon nanowire transistor in biomolecular modification and detection

    International Nuclear Information System (INIS)

    Tsai, Chia-Chang; Chiang, Pei-Ling; Lin, Tsung-Wu; Chen, Yit-Tsong; Sun, Chih-Jung; Tsai, Ming-Hsueh; Chang, Yun-Chorng

    2011-01-01

    Using a silicon nanowire field-effect transistor (SiNW-FET) for biomolecule detections, we selected 3-(mercaptopropyl)trimethoxysilane (MPTMS), N-[6-(biotinamido)hexyl]-3 ' -(2 ' -pyridyldithio) propionamide (biotin-HPDP), and avidin, respectively, as the designated linker, receptor, and target molecules as a study model, where the biotin molecules were modified on the SiNW-FET to act as a receptor for avidin. We applied high-resolution scanning Kelvin probe force microscopy (KPFM) to detect the modified/bound biomolecules by measuring the induced change of the surface potential (ΔΦ s ) on the SiNW-FET under ambient conditions. After biotin-immobilization and avidin-binding, the ΔΦ s on the SiNW-FET characterized by KPFM was demonstrated to correlate to the conductance change inside the SiNW-FET acquired in aqueous solution. The ΔΦ s values on the SiNW-FET caused by the same biotin-immobilization and avidin-binding were also measured from drain current versus gate voltage curves (I d -V g ) in both aqueous condition and dried state. For comparison, we also study the ΔΦ s values on a Si wafer caused by the same biotin-immobilization and avidin-binding through KPFM and ζ potential measurements. This study has demonstrated that the surface potential measurement on a SiNW-FET by KPFM can be applied as a diagnostic tool that complements the electrical detection with a SiNW-FET sensor. Although the KPFM experiments were carried out under ambient conditions, the measured surface properties of a SiNW-FET are qualitatively valid compared with those obtained by other biosensory techniques performed in liquid environment.

  9. Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures

    Science.gov (United States)

    Mwangi, Joseph N.; Wang, Ning; Ritts, Andrew; Kunz, James L.; Ingersoll, Christopher G.; Li, Hao; Deng, Baolin

    2011-01-01

    Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 h. Midges, mussels, and oligochaetes were exposed only to sonicated SiCNW in water for 96 h. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 d (44% SiCNW on dry wt basis). Mean 48-h survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-h exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-d exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods, sonicated SiCNW in water were acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Enhancement of Light Absorption in Silicon Nanowire Photovoltaic Devices with Dielectric and Metallic Grating Structures.

    Science.gov (United States)

    Park, Jin-Sung; Kim, Kyoung-Ho; Hwang, Min-Soo; Zhang, Xing; Lee, Jung Min; Kim, Jungkil; Song, Kyung-Deok; No, You-Shin; Jeong, Kwang-Yong; Cahoon, James F; Kim, Sun-Kyung; Park, Hong-Gyu

    2017-12-13

    We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a Si 3 N 4 grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the Si 3 N 4 gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer. Furthermore, we demonstrate Si nanowire photovoltaic devices with Ag gratings using the same transfer method. Measurements on the fabricated devices reveal approximately 27.1% enhancement in light absorption compared to that of the same devices without the Ag gratings without any degradation of electrical properties. We believe that our polymer-assisted transfer method is not limited to the fabrication of grating-incorporated nanowire photovoltaic devices but can also be generically applied for the implementation of complex nanoscale structures toward the development of multifunctional optoelectronic devices.

  15. On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell.

    Science.gov (United States)

    Petterson, Maureen K; Lemaitre, Maxime G; Shen, Yu; Wadhwa, Pooja; Hou, Jie; Vasilyeva, Svetlana V; Kravchenko, Ivan I; Rinzler, Andrew G

    2015-09-30

    Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separated there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm(2) AM1.5G illumination, results in a short-circuit current density of 35 mA/cm(2) and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. A deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.

  16. Piezoelectric effect in InAs/InP quantum rod nanowires grown on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Anufriev, Roman; Chauvin, Nicolas, E-mail: nicolas.chauvin@insa-lyon.fr; Bru-Chevallier, Catherine [Université de Lyon, Institut des Nanotechnologies de Lyon (INL)-UMR5270-CNRS, INSA-Lyon, 7 avenue Jean Capelle, 69621 Villeurbanne (France); Khmissi, Hammadi [Université de Monastir, Laboratoire de Micro-Optoélectronique et Nanostructures (LMON), Faculté des Sciences, Avenue de l' environnement, 5019 Monastir (Tunisia); Naji, Khalid; Gendry, Michel [Université de Lyon, Institut des Nanotechnologies de Lyon (INL)-UMR5270-CNRS, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Patriarche, Gilles [Laboratoire de Photonique et de Nanostructures (LPN), UPR20-CNRS, route de Nozay, 91460 Marcoussis (France)

    2014-05-05

    We report on the evidence of a strain-induced piezoelectric field in wurtzite InAs/InP quantum rod nanowires. This electric field, caused by the lattice mismatch between InAs and InP, results in the quantum confined Stark effect and, as a consequence, affects the optical properties of the nanowire heterostructure. It is shown that the piezoelectric field can be screened by photogenerated carriers or removed by increasing temperature. Moreover, a dependence of the piezoelectric field on the quantum rod diameter is observed in agreement with simulations of wurtzite InAs/InP quantum rod nanowire heterostructures.

  17. Correlation between oxidant concentrations, morphological aspects and etching kinetics of silicon nanowires during silver-assist electroless etching

    Science.gov (United States)

    Moumni, Besma; Jaballah, Abdelkader Ben

    2017-12-01

    Silicon porosification by silver assisted chemical etching (Ag-ACE) for a short range of H2O2 concentration is reported. We experimentally show that porous silicon (PSi) is obtained for 1% H2O2, whereas silicon nanowires (SiNWs) appeared by simply tuning the concentration of H2O2 to relatively high concentrations up to 8%. The morphological aspects are claimed by scanning electron microscopy proving that the kinetics of SiNWs formation display nonlinear relationships versus H2O2 concentration and etching time. A semi-qualitative electrochemical etching model based on local anodic, Ic, and cathodic, Ia, currents is proposed to explain the different morphological changes, and to unveil the formation pathways of both PS and SiNWs. More importantly, an efficient antireflective character for silicon solar cell (reflectance close to 2%) is realized at 8% H2O2. In addition, the luminescence of the prepared Si-nanostructures is claimed by photoluminescence which exhibit a large enhancement of the intensity and a blue shift for narrow and deep SiNWs.

  18. 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.

  19. Coaxial nanowire resonant tunneling diodes from non-polar AlN/GaN on silicon

    Science.gov (United States)

    Carnevale, S. D.; Marginean, C.; Phillips, P. J.; Kent, T. F.; Sarwar, A. T. M. G.; Mills, M. J.; Myers, R. C.

    2012-04-01

    Resonant tunneling diodes are formed using AlN/GaN core-shell nanowire heterostructures grown by plasma assisted molecular beam epitaxy on n-Si(111) substrates. By using a coaxial geometry, these devices take advantage of non-polar (m-plane) nanowire sidewalls. Device modeling predicts non-polar orientation should enhance resonant tunneling compared to a polar structure, and that AlN double barriers will lead to higher peak-to-valley current ratios compared to AlGaN barriers. Electrical measurements of ensembles of nanowires show negative differential resistance appearing only at cryogenic temperature. Individual nanowire measurements show negative differential resistance at room temperature with peak current density of 5 × 105 A/cm2.

  20. 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.

  1. Engineering in-plane silicon nanowire springs for highly stretchable electronics

    Science.gov (United States)

    Xue, Zhaoguo; Dong, Taige; Zhu, Zhimin; Zhao, Yaolong; Sun, Ying; Yu, Linwei

    2018-01-01

    Crystalline silicon (c-Si) is unambiguously the most important semiconductor that underpins the development of modern microelectronics and optoelectronics, though the rigid and brittle nature of bulk c-Si makes it difficult to implement directly for stretchable applications. Fortunately, the one-dimensional (1D) geometry, or the line-shape, of Si nanowire (SiNW) can be engineered into elastic springs, which indicates an exciting opportunity to fabricate highly stretchable 1D c-Si channels. The implementation of such line-shape-engineering strategy demands both a tiny diameter of the SiNWs, in order to accommodate the strains under large stretching, and a precise growth location, orientation and path control to facilitate device integration. In this review, we will first introduce the recent progresses of an in-plane self-assembly growth of SiNW springs, via a new in-plane solid-liquid-solid (IPSLS) mechanism, where mono-like but elastic SiNW springs are produced by surface-running metal droplets that absorb amorphous Si thin film as precursor. Then, the critical growth control and engineering parameters, the mechanical properties of the SiNW springs and the prospects of developing c-Si based stretchable electronics, will be addressed. This efficient line-shape-engineering strategy of SiNW springs, accomplished via a low temperature batch-manufacturing, holds a strong promise to extend the legend of modern Si technology into the emerging stretchable electronic applications, where the high carrier mobility, excellent stability and established doping and passivation controls of c-Si can be well inherited. Project supported by the National Basic Research 973 Program (No. 2014CB921101), the National Natural Science Foundation of China (No. 61674075), the National Key Research and Development Program of China (No. 2017YFA0205003), the Jiangsu Excellent Young Scholar Program (No. BK20160020), the Scientific and Technological Support Program in Jiangsu Province (No. BE

  2. 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).

  3. Atomically abrupt silicon-germanium axial heterostructure nanowires synthesized in a solvent vapor growth system.

    Science.gov (United States)

    Geaney, Hugh; Mullane, Emma; Ramasse, Quentin M; Ryan, Kevin M

    2013-04-10

    The growth of Si/Ge axial heterostructure nanowires in high yield using a versatile wet chemical approach is reported. Heterostructure growth is achieved using the vapor zone of a high boiling point solvent as a reaction medium with an evaporated tin layer as the catalyst. The low solubility of Si and Ge within the Sn catalyst allows the formation of extremely abrupt heterojunctions of the order of just 1-2 atomic planes between the Si and Ge nanowire segments. The compositional abruptness was confirmed using aberration corrected scanning transmission electron microscopy and atomic level electron energy loss spectroscopy. Additional analysis focused on the role of crystallographic defects in determining interfacial abruptness and the preferential incorporation of metal catalyst atoms near twin defects in the nanowires.

  4. Integrated nanoscale silicon sensors using top-down fabrication

    Science.gov (United States)

    Elibol, O. H.; Morisette, D.; Akin, D.; Denton, J. P.; Bashir, R.

    2003-12-01

    Semiconductor device-based sensing of chemical and biological entities has been demonstrated through the use of micro- and nanoscale field-effect devices and close variants. Although carbon nanotubes and silicon nanowires have been demonstrated as single molecule biosensors, the fabrication methods that have been used for creating these devices are typically not compatible with modern semiconductor manufacturing techniques and their large scale integration is problematic. These shortcomings are addressed by recent advancements in microelectronic fabrication techniques which resulted in the realization of nanowire-like structures. Here we report a method to fabricate silicon nanowires at precise locations using such techniques. Our method allows for the realization of truly integrated sensors capable of production of dense arrays. Sensitivity of these devices to changes in the ambient gas composition is also shown.

  5. Silicon nanowires with controlled sidewall profile and roughness fabricated by thin-film dewetting and metal-assisted chemical etching

    Science.gov (United States)

    Azeredo, B. P.; Sadhu, J.; Ma, J.; Jacobs, K.; Kim, J.; Lee, K.; Eraker, J. H.; Li, X.; Sinha, S.; Fang, N.; Ferreira, P.; Hsu, K.

    2013-06-01

    This paper presents a non-lithographic approach to generate wafer-scale single crystal silicon nanowires (SiNWs) with controlled sidewall profile and surface morphology. The approach begins with silver (Ag) thin-film thermal dewetting, gold (Au) deposition and lift-off to generate a large-scale Au mesh on Si substrates. This is followed by metal-assisted chemical etching (MacEtch), where the Au mesh serves as a catalyst to produce arrays of smooth Si nanowires with tunable taper up to 13°. The mean diameter of the thus fabricated SiNWs can be controlled to range from 62 to 300 nm with standard deviations as small as 13.6 nm, and the areal coverage of the wire arrays can be up to 46%. Control of the mean wire diameter is achieved by controlling the pore diameter of the metallic mesh which is, in turn, controlled by adjusting the initial thin-film thickness and deposition rate. To control the wire surface morphology, a post-fabrication roughening step is added to the approach. This step uses Au nanoparticles and slow-rate MacEtch to produce rms surface roughness up to 3.6 nm.

  6. Copper silicide/silicon nanowire heterostructures: in situ TEM observation of growth behaviors and electron transport properties.

    Science.gov (United States)

    Chiu, Chung-Hua; Huang, Chun-Wei; Chen, Jui-Yuan; Huang, Yu-Ting; Hu, Jung-Chih; Chen, Lien-Tai; Hsin, Cheng-Lun; Wu, Wen-Wei

    2013-06-07

    Copper silicide has been studied in the applications of electronic devices and catalysts. In this study, Cu3Si/Si nanowire heterostructures were fabricated through solid state reaction in an in situ transmission electron microscope (TEM). The dynamic diffusion of the copper atoms in the growth process and the formation mechanism are characterized. We found that two dimensional stacking faults (SF) may retard the growth of Cu3Si. Due to the evidence of the block of edge-nucleation (heterogeneous) by the surface oxide, center-nucleation (homogeneous) is suggested to dominate the silicidation. Furthermore, the electrical transport properties of various silicon channel length with Cu3Si/Si heterostructure interfaces and metallic Cu3Si NWs have been investigated. The observations not only provided an alternative pathway to explore the formation mechanisms and interface properties of Cu3Si/Si, but also suggested the potential application of Cu3Si at nanoscale for future processing in nanotechnology.

  7. Ultra-sensitive and selective detection of mercury ion (Hg2+) using free-standing silicon nanowire sensors

    Science.gov (United States)

    Jin, Yan; Gao, Anran; Jin, Qinghui; Li, Tie; Wang, Yuelin; Zhao, Jianlong

    2018-04-01

    In this paper, ultra-sensitive and highly selective Hg2+ detection in aqueous solutions was studied by free-standing silicon nanowire (SiNW) sensors. The all-around surface of SiNW arrays was functionalized with (3-Mercaptopropyl)trimethoxysilane serving as Hg2+ sensitive layer. Due to effective electrostatic control provided by the free-standing structure, a detection limit as low as 1 ppt was obtained. A linear relationship (R 2 = 0.9838) between log(CHg2+ ) and a device current change from 1 ppt to 5 ppm was observed. Furthermore, the developed SiNW sensor exhibited great selectivity for Hg2+ over other heavy metal ions, including Cd2+. Given the extraordinary ability for real-time Hg2+ detection, the small size and low cost of the SiNW device, it is expected to be a potential candidate in field detection of environmentally toxic mercury.

  8. Silicon nanowires with high-k hafnium oxide dielectrics for sensitive detection of small nucleic acid oligomers.

    Science.gov (United States)

    Dorvel, Brian R; Reddy, Bobby; Go, Jonghyun; Duarte Guevara, Carlos; Salm, Eric; Alam, Muhammad Ashraful; Bashir, Rashid

    2012-07-24

    Nanobiosensors based on silicon nanowire field effect transistors offer advantages of low cost, label-free detection, and potential for massive parallelization. As a result, these sensors have often been suggested as an attractive option for applications in point-of-care (POC) medical diagnostics. Unfortunately, a number of performance issues, such as gate leakage and current instability due to fluid contact, have prevented widespread adoption of the technology for routine use. High-k dielectrics, such as hafnium oxide (HfO(2)), have the known ability to address these challenges by passivating the exposed surfaces against destabilizing concerns of ion transport. With these fundamental stability issues addressed, a promising target for POC diagnostics and SiNWFETs has been small oligonucleotides, more specifically, microRNA (miRNA). MicroRNAs are small RNA oligonucleotides which bind to mRNAs, causing translational repression of proteins, gene silencing, and expressions are typically altered in several forms of cancer. In this paper, we describe a process for fabricating stable HfO(2) dielectric-based silicon nanowires for biosensing applications. Here we demonstrate sensing of single-stranded DNA analogues to their microRNA cousins using miR-10b and miR-21 as templates, both known to be upregulated in breast cancer. We characterize the effect of surface functionalization on device performance using the miR-10b DNA analogue as the target sequence and different molecular weight poly-l-lysine as the functionalization layer. By optimizing the surface functionalization and fabrication protocol, we were able to achieve <100 fM detection levels of the miR-10b DNA analogue, with a theoretical limit of detection of 1 fM. Moreover, the noncomplementary DNA target strand, based on miR-21, showed very little response, indicating a highly sensitive and highly selective biosensing platform.

  9. Low-loss and low-crosstalk 8 × 8 silicon nanowire AWG routers fabricated with CMOS technology.

    Science.gov (United States)

    Wang, Jing; Sheng, Zhen; Li, Le; Pang, Albert; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Qi, Minghao; Gan, Fuwan

    2014-04-21

    Low-loss and low-crosstalk 8 × 8 arrayed waveguide grating (AWG) routers based on silicon nanowire waveguides are reported. A comparative study of the measurement results of the 3.2 nm-channel-spacing AWGs with three different designs is performed to evaluate the effect of each optimal technique, showing that a comprehensive optimization technique is more effective to improve the device performance than a single optimization. Based on the comprehensive optimal design, we further design and experimentally demonstrate a new 8-channel 0.8 nm-channel-spacing silicon AWG router for dense wavelength division multiplexing (DWDM) application with 130 nm CMOS technology. The AWG router with a channel spacing of 3.2 nm (resp. 0.8 nm) exhibits low insertion loss of 2.32 dB (resp. 2.92 dB) and low crosstalk of -20.5~-24.5 dB (resp. -16.9~-17.8 dB). In addition, sophisticated measurements are presented including all-input transmission testing and high-speed WDM system demonstrations for these routers. The functionality of the Si nanowire AWG as a router is characterized and a good cyclic rotation property is demonstrated. Moreover, we test the optical eye diagrams and bit-error-rates (BER) of the de-multiplexed signal when the multi-wavelength high-speed signals are launched into the AWG routers in a system experiment. Clear optical eye diagrams and low power penalty from the system point of view are achieved thanks to the low crosstalk of the AWG devices.

  10. Study of Ag induced bimetallic (Au-Ag) nanowires on silicon (5 5 12) surfaces: Experiment and theoretical aspects

    Science.gov (United States)

    Bhukta, Anjan; Bagarti, Trilochan; Guha, Puspendu; Ravulapalli, Sathyavathi; Satpati, Biswarup; Rakshit, Bipul; Maiti, Paramita; Parlapalli, Venkata Satyam

    2017-10-01

    The reconstructed vicinal (high index) silicon surfaces, such as, Si (5 5 12) composes row-like structures that can be used as templates for growing aligned nanowires. By using a sub-monolayers of Ag, prior to Au deposition on reconstructed Si (5 512) surface, intermixing of Au and Ag, enhancement of aspect ratio of bimetallic Au-Ag nanowires with tunable morphology is reported. This is attributed to a combined effect of pre-grown Ag strips as nucleation centers for incoming Au ad-atoms and anisotropic Au-Ag intermixing. To achieve optimum conditions for the growth of larger aspect ratio Au-Ag nanostructures, the growth kinetics have been studied by varying growth and annealing temperatures. At ≈400 °C, the Ag diffused into silicon substrate and the inter-diffusion found to inhibit the formation of Au-Ag bimetallic nanostructures. Controlled experiments under ultra-high vacuum condition in a molecular beam epitaxy system and in-situ scanning tunneling microscopy measurements along with ex-situ scanning transmission and secondary electron microscopy measurements have been carried out to understand the bimetallic nanostructure growth. Kinetic Monte Carlo (KMC) simulations based on kinematics of ad-atoms on an anisotropic template with a solid on solid model in which the relative ratios of binding energies (that are obtained from the Density Functional Theory) have been used and the KMC simulations results agree with the experimental observations. Advantage of having bimetallic structures as effective substrates for Surface enhanced Raman spectroscopy application is demonstrated by detecting Rhodamine 6 G (R6G) molecule at the concentration of 10-7M.

  11. In-Channel-Grown Polypyrrole Nanowire for the Detection of DNA Hybridization in an Electrochemical Microfluidic Biosensor

    Directory of Open Access Journals (Sweden)

    Thi Luyen Tran

    2015-01-01

    Full Text Available A triple electrode setup with a Pt pseudo-reference electrode integrated in a polydimethylsiloxane- (PDMS- based microchamber was designed and fabricated. The integrated electrodes were deposited onto SiO2/Si substrate by sputtering. The PDMS microchamber was patterned using an SU-8 mold and sealed with electrodes in oxygen plasma. Polypyrrole nanowires (PPy NWs were electrochemically grown in situ at an accurate position of the working electrode in the sealed microchamber instead of in an open system. The DNA probe sequences were simply introduced into the channel to form bonds with the nanowires. A detection limit of 20 pM was achieved using a lock-in amplifier. The electrochemical characteristics produced by the hybridization of DNA strands in the microchamber showed a good signal/noise ratio and high sensitivity. Measurement of the DNA sensor in narrow space also required much less volume of the analytical sample compared with that in an open measuring cell. Results showed that this simple system can potentially fabricate nanostructures and detect bio/chemical molecules in a sealed system.

  12. Advances in nanowire transistors for biological analysis and cellular investigation.

    Science.gov (United States)

    Li, Bor-Ran; Chen, Chiao-Chen; Kumar, U Rajesh; Chen, Yit-Tsong

    2014-04-07

    Electrical biosensors based on silicon nanowire field-effect transistors (SiNW-FETs) have attracted enormous interest in the biosensing field. SiNW-FETs have proven to be significant and efficient in detecting diverse biomolecular species with the advantages of high probing sensitivity, target selectivity, real-time recording and label-free detection. In recent years, significant advances in biosensors have been achieved, particularly for cellular investigation and biomedical diagnosis. In this critical review, we will report on the latest developments in biosensing with SiNW-FETs and discuss recent advancements in the innovative designs of SiNW-FET devices. This critical review introduces the basic instrumental setup and working principle of SiNW-FETs. Technical approaches that attempted to enhance the detection sensitivity and target selectivity of SiNW-FET sensors are discussed. In terms of applications, we review the recent achievements with SiNW-FET biosensors for the investigations of protein-protein interaction, DNA/RNA/PNA hybridization, virus detection, cellular recording, biological kinetics, and clinical diagnosis. In addition, the novel architecture designs of the SiNW-FET devices are highlighted in studies of live neuron cells, electrophysiological measurements and other signal transduction pathways. Despite these remarkable achievements, certain improvements remain necessary in the device performance and clinical applications of FET-based biosensors; thus, several prospects about the future development of nanowire transistor-based instruments for biosensing employments are discussed at the end of this review.

  13. Solution immersed silicon (SIS)-based biosensors: a new approach in biosensing.

    Science.gov (United States)

    Diware, M S; Cho, H M; Chegal, W; Cho, Y J; Jo, J H; O, S W; Paek, S H; Yoon, Y H; Kim, D

    2015-02-07

    A novel, solution immersed silicon (SIS)-based sensor has been developed which employs the non-reflecting condition (NRC) for a p-polarized wave. The SIS sensor's response is almost independent of change in the refractive index (RI) of a buffer solution (BS) which makes it capable of measuring low-concentration and/or low-molecular-weight compounds.

  14. Application of silicon nanowires and indium tin oxide surfaces in desorption electrospray ionization

    Czech Academy of Sciences Publication Activity Database

    Pól, Jaroslav; Novák, Petr; Volný, Michael; Kruppa, G. H.; Kostiainen, R.; Lemr, Karel; Havlíček, Vladimír

    2008-01-01

    Roč. 14, č. 6 (2008), s. 391-399 ISSN 1469-0667 R&D Projects: GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : mass spectrometry * desorption electrospray ionization * nanowires Subject RIV: CE - Biochemistry Impact factor: 1.167, year: 2008

  15. 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

    , 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...

  16. A novel passivation process of silicon nanowires by a low-cost PECVD technique for deposition of hydrogenated silicon nitride using SiH4 and N2 as precursor gases

    Science.gov (United States)

    Bouaziz, Lamia; Dridi, Donia; Karyaoui, Mokhtar; Angelova, Todora; Sanchez Plaza, Guillermo; Chtourou, Radhouane

    2017-03-01

    In this work, a different SiNx passivation process of silicon nanowires has been opted for the deposition of a hydrogenated silicon nitride (SiNx:H) by a low-cost plasma enhanced chemical vapor deposition (PECVD) using silane ( SiH4 and nitrogen ( N2 as reactive gases. This study is focused on the effect of the gas flow ratio on chemical composition, morphological, optical and optoelectronic properties of silicon nanowires. The existence of Si-N and Si-H bonds was proven by the Fourier transmission infrared (FTIR) spectrum. Morphological structures were shown by scanning electron microscopy (SEM), and the roughness was investigated by atomic force microscopy (AFM). A low reflectivity less than 6% in the wavelength range 250-1200nm has been shown by UV-visible spectroscopy. Furthermore, the thickness and the refractive index of the passivation layer is determined by ellipsometry measurements. As a result, an improvement in minority carrier lifetime has been obtained by reducing surface recombination of silicon nanowires.

  17. In-situ Mueller matrix ellipsometry of silicon nanowires grown by plasma-enhanced vapor-liquid-solid method for radial junction solar cells

    Science.gov (United States)

    Mrazkova, Z.; Foldyna, M.; Misra, S.; Al-Ghzaiwat, M.; Postava, K.; Pištora, J.; Roca i Cabarrocas, P.

    2017-11-01

    In-situ Mueller matrix spectroscopic ellipsometry was applied for monitoring the silicon nanowire growth by plasma-enhanced vapor-liquid-solid method. The technique is proposed as a real-time, non-destructive, and non-invasive characterization of the deposition process in a plasma-enhanced chemical vapor deposition reactor. The data have been taken by spectrally resolved Mueller matrix ellipsometer every 1 min during the 8-10 min long nanowire growth process. We have developed an easy-to-apply optical model to fit the experimental data, which enables to study the evolution of the parameters of the structure during initial stages of the growth. The first results provide information about the effective deposition rate determined from the linear increase of the deposited silicon volume with the deposition time.

  18. A silicon nanowire-reduced graphene oxide composite as a high-performance lithium ion battery anode material.

    Science.gov (United States)

    Ren, Jian-Guo; Wang, Chundong; Wu, Qi-Hui; Liu, Xiang; Yang, Yang; He, Lifang; Zhang, Wenjun

    2014-03-21

    Toward the increasing demands of portable energy storage and electric vehicle applications, silicon has been emerging as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, serious pulverization of bulk silicon during cycling limits its cycle life. Herein, we report a novel hierarchical Si nanowire (Si NW)-reduced graphene oxide (rGO) composite fabricated using a solvothermal method followed by a chemical vapor deposition process. In the composite, the uniform-sized [111]-oriented Si NWs are well dispersed on the rGO surface and in between rGO sheets. The flexible rGO enables us to maintain the structural integrity and to provide a continuous conductive network of the electrode, which results in over 100 cycles serving as an anode in half cells at a high lithium storage capacity of 2300 mA h g(-1). Due to its [111] growth direction and the large contact area with rGO, the Si NWs in the composite show substantially enhanced reaction kinetics compared with other Si NWs or Si particles.

  19. Nanowire arrays in multicrystalline silicon thin films on glass: a promising material for research and applications in nanotechnology.

    Science.gov (United States)

    Schmitt, Sebastian W; Schechtel, Florian; Amkreutz, Daniel; Bashouti, Muhammad; Srivastava, Sanjay K; Hoffmann, Björn; Dieker, Christel; Spiecker, Erdmann; Rech, Bernd; Christiansen, Silke H

    2012-08-08

    Silicon nanowires (SiNW) were formed on large grained, electron-beam crystallized silicon (Si) thin films of only ∼6 μm thickness on glass using nanosphere lithography (NSL) in combination with reactive ion etching (RIE). Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) studies revealed outstanding structural properties of this nanomaterial. It could be shown that SiNWs with entirely predetermined shapes including lengths, diameters and spacings and straight side walls form independently of their crystalline orientation and arrange in ordered arrays on glass. Furthermore, for the first time grain boundaries could be observed in individual, straightly etched SiNWs. After heat treatment an electronic grade surface quality of the SiNWs could be shown by X-ray photoelectron spectroscopy (XPS). Integrating sphere measurements show that SiNW patterning of the multicrystalline Si (mc-Si) starting thin film on glass substantially increases absorption and reduces reflection, as being desired for an application in thin film photovoltaics (PV). The multicrystalline SiNWs directly mark a starting point for research not only in PV but also in other areas like nanoelectronics, surface functionalization, and nanomechanics.

  20. 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.

  1. Equivalence of the equilibrium and the nonequilibrium molecular dynamics methods for thermal conductivity calculations: From bulk to nanowire silicon

    Science.gov (United States)

    Dong, Haikuan; Fan, Zheyong; Shi, Libin; Harju, Ari; Ala-Nissila, Tapio

    2018-03-01

    Molecular dynamics (MD) simulations play an important role in studying heat transport in complex materials. The lattice thermal conductivity can be computed either using the Green-Kubo formula in equilibrium MD (EMD) simulations or using Fourier's law in nonequilibrium MD (NEMD) simulations. These two methods have not been systematically compared for materials with different dimensions and inconsistencies between them have been occasionally reported in the literature. Here we give an in-depth comparison of them in terms of heat transport in three allotropes of Si: three-dimensional bulk silicon, two-dimensional silicene, and quasi-one-dimensional silicon nanowire. By multiplying the correlation time in the Green-Kubo formula with an appropriate effective group velocity, we can express the running thermal conductivity in the EMD method as a function of an effective length and directly compare it to the length-dependent thermal conductivity in the NEMD method. We find that the two methods quantitatively agree with each other for all the systems studied, firmly establishing their equivalence in computing thermal conductivity.

  2. Improvement of efficiency in graphene/gallium nitride nanowire on Silicon photoelectrode for overall water splitting

    Science.gov (United States)

    Bae, Hyojung; Rho, Hokyun; Min, Jung-Wook; Lee, Yong-Tak; Lee, Sang Hyun; Fujii, Katsushi; Lee, Hyo-Jong; Ha, Jun-Seok

    2017-11-01

    Gallium nitride (GaN) nanowires are one of the most promising photoelectrode materials due to their high stability in acidic and basic electrolytes, and tunable band edge potentials. In this study, GaN nanowire arrays (GaN NWs) were prepared by molecular beam epitaxy (MBE); their large surface area enhanced the solar to hydrogen conversion efficiency. More significantly, graphene was grown by chemical vapor deposition (CVD), which enhanced the electron transfer between NWs for water splitting and protected the GaN NW surface. Structural characterizations of the prepared composite were performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocurrent density of Gr/GaN NWs exhibited a two-fold increase over pristine GaN NWs and sustained water splitting up to 70 min. These improvements may accelerate possible applications for hydrogen generation with high solar to hydrogen conversion efficiency.

  3. Vertical Silicon Nanowire Platform for Low Power Electronics and Clean Energy Applications

    Directory of Open Access Journals (Sweden)

    D.-L. Kwong

    2012-01-01

    Full Text Available This paper reviews the progress of the vertical top-down nanowire technology platform developed to explore novel device architectures and integration schemes for green electronics and clean energy applications. Under electronics domain, besides having ultimate scaling potential, the vertical wire offers (1 CMOS circuits with much smaller foot print as compared to planar transistor at the same technology node, (2 a natural platform for tunneling FETs, and (3 a route to fabricate stacked nonvolatile memory cells. Under clean energy harvesting area, vertical wires could provide (1 cost reduction in photovoltaic energy conversion through enhanced light trapping and (2 a fully CMOS compatible thermoelectric engine converting waste-heat into electricity. In addition to progress review, we discuss the challenges and future prospects with vertical nanowires platform.

  4. Silicon-germanium nanowire tunnel-FETs with homo- and heterostructure tunnel junctions

    Science.gov (United States)

    Richter, S.; Blaeser, S.; Knoll, L.; Trellenkamp, S.; Fox, A.; Schäfer, A.; Hartmann, J. M.; Zhao, Q. T.; Mantl, S.

    2014-08-01

    Experimental results on tunneling field-effect transistors (TFETs) based on strained SiGe on SOI nanowire arrays are presented. A heterostructure SiGe/Si TFET with a vertical tunnel junction consisting of an in situ doped SiGe source and a Si channel with a minimum inverse subthreshold slope of 90 mV/dec is demonstrated. An increase in tunneling area results in higher on-current. The in situ doped heterojunction TFET shows great improvement compared to a homojunction SiGe on SOI nanowire design with implanted junctions. Temperature dependent measurements and device simulations are performed in order to analyze the tunnel transport mechanism in the devices.

  5. Gate bias-dependent junction characteristics of silicon nanowires suspended between polysilicon electrodes

    Directory of Open Access Journals (Sweden)

    Yun-Hi Lee and Sungim Park

    2011-01-01

    Full Text Available Realistic integration of 1D materials into future nanodevices is limited by the lack of a manipulation process that allows a large number of nanowires to be arranged into an integrated circuit. In this work, we have grown Si nanowire bridges using a thin-film catalyst in a batch process at 200 °C and characterized the produced devices consisting of a p+-Si contact electrode, a suspended Si nanochannel, and a polysilicon contact electrode. Both the electrodes and connecting lines are made of Si-based materials by conventional low-pressure chemical vapor deposition. The results indicate that these devices can act as gate-controllable Schottky diodes in integrated nanocircuits.

  6. Rectifying properties of p-GaN nanowires and an n-silicon heterojunction vertical diode.

    Science.gov (United States)

    Manna, Sujit; Ashok, Vishal D; De, S K

    2010-12-01

    The heterojunction of a Pd-doped p-GaN nanowire and n-Si (100) is fabricated vertically by the vapor-liquid-solid method. The average diameter of the nanowire is 40 nm. The vertical junction reveals a significantly high rectification ratio of 10(3) at 5 V, a moderate ideality factor of ∼2, and a high breakdown voltage of ∼40 V. The charge transport across the p-n junction is dominated by the electron-hole recombination process. The voltage dependence of capacitance indicates a graded-type junction. The resistance of the junction decreases with an increase in the bias voltage confirmed by impedance measurements.

  7. One-Dimensional Hole Gas in Germanium/Silicon Nanowire Heterostructures

    OpenAIRE

    Lu, Wei; Xiang, Jie; Timko, Brian P.; Wu, Yue; Lieber, Charles M.

    2005-01-01

    Two-dimensional electron and hole gas systems, enabled through band structure design and epitaxial growth on planar substrates, have served as key platforms for fundamental condensed matter research and high-performance devices. The analogous development of one-dimensional (1D) electron or hole gas systems through controlled growth on 1D nanostructure substrates, which could open up opportunities beyond existing carbon nanotube and nanowire systems, has not been realized. Here, we report the ...

  8. Use of self-assembled peptide nanostructures for the fabrication of silicon nanowires

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime; Bakmand, Tania

    2011-01-01

    1. INTRODUCTION Self-assembled diphenylalanine peptide nanotubes provide a means of achieving nanostructured materials in a very simple and fast way. Recent discoveries have shown that this unique material, in addition to remaining stable under dry conditions, rapidly dissolves in water making it...... nanowires. Furthermore, the PNTs could be used as lift-off masks for the patterning during deposition of materials. REFERENCES [1] K. B. Andersen, J. Castillo-León, M. Hedstrom, W. E. Svendsen. Nanoscale. 3, 994-998, (2011)...

  9. Differential Releases of Dopamine and Neuropeptide Y from Histamine-Stimulated PC12 Cells Detected by an Aptamer-Modified Nanowire Transistor.

    Science.gov (United States)

    Banerjee, Subhasree; Hsieh, Ying-Jhu; Liu, Chia-Rung; Yeh, Nai-Hsing; Hung, Hui-Hsing; Lai, Yew-Seng; Chou, Ai-Chuan; Chen, Yit-Tsong; Pan, Chien-Yuan

    2016-10-01

    Silicon nanowire field-effect transistors modified with specific aptamers can directly detect the minute dopamine and neuropeptide Y released from cells. The binding of these molecules to the aptamers results in a conductance change of the transistor biosensor and illustrates the differential releasing mechanisms of these molecules stored in various vesicle pools. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Superparamagnetic iron oxide nanoparticle attachment on array of micro test tubes and microbeakers formed on p-type silicon substrate for biosensor applications

    Directory of Open Access Journals (Sweden)

    Raja Sufi

    2011-01-01

    Full Text Available Abstract A uniformly distributed array of micro test tubes and microbeakers is formed on a p-type silicon substrate with tunable cross-section and distance of separation by anodic etching of the silicon wafer in N, N-dimethylformamide and hydrofluoric acid, which essentially leads to the formation of macroporous silicon templates. A reasonable control over the dimensions of the structures could be achieved by tailoring the formation parameters, primarily the wafer resistivity. For a micro test tube, the cross-section (i.e., the pore size as well as the distance of separation between two adjacent test tubes (i.e., inter-pore distance is typically approximately 1 μm, whereas, for a microbeaker the pore size exceeds 1.5 μm and the inter-pore distance could be less than 100 nm. We successfully synthesized superparamagnetic iron oxide nanoparticles (SPIONs, with average particle size approximately 20 nm and attached them on the porous silicon chip surface as well as on the pore walls. Such SPION-coated arrays of micro test tubes and microbeakers are potential candidates for biosensors because of the biocompatibility of both silicon and SPIONs. As acquisition of data via microarray is an essential attribute of high throughput bio-sensing, the proposed nanostructured array may be a promising step in this direction.

  11. Sb2S3 Quantum-Dot Sensitized Solar Cells with Silicon Nanowire Photoelectrode

    Directory of Open Access Journals (Sweden)

    You-Da Hsieh

    2015-01-01

    Full Text Available We propose a novel quantum-dot sensitized solar cell (QDSSC structure that employs a quantum dot/semiconductor silicon (QD/Si coaxial nanorod array to replace the conventional dye/TiO2/TCO photoelectrode. We replaced the backlight input mode with top-side illumination and used a quantum dot to replace dye as the light-absorbing material. Photon-excited photoelectrons can be effectively transported to each silicon nanorod and conveyed to the counter electrode. We use two-stage metal-assisted etching (MAE to fabricate the micro-nano hybrid structure on a silicon substrate. We then use the chemical bath deposition (CBD method to synthesize a Sb2S3 quantum dot on the surface of each silicon nanorod to form the photoelectrode for the quantum dot/semiconductor silicon coaxial nanorod array. We use a xenon lamp to simulate AM 1.5 G (1000 W/m2 sunlight. Then, we investigate the influence of different silicon nanorod arrays and CBD deposition times on the photoelectric conversion efficiency. When an NH (N-type with high resistance silicon substrate is used, the QD/Si coaxial nanorod array synthesized by three runs of Sb2S3 deposition shows the highest photoelectric conversion efficiency of 0.253%. The corresponding short-circuit current density, open-circuit voltage, and fill factor are 5.19 mA/cm2, 0.24 V, and 20.33%, respectively.

  12. High performance ring oscillators from 10-nm wide silicon nanowire field-effect transistors

    KAUST Repository

    Huang, Ruo-Gu

    2011-06-24

    We explore 10-nm wide Si nanowire (SiNW) field-effect transistors (FETs) for logic applications, via the fabrication and testing of SiNW-based ring oscillators. We report on SiNW surface treatments and dielectric annealing, for producing SiNW FETs that exhibit high performance in terms of large on/off-state current ratio (~108), low drain-induced barrier lowering (~30 mV) and low subthreshold swing (~80 mV/decade). The performance of inverter and ring-oscillator circuits fabricated from these nanowire FETs are also explored. The inverter demonstrates the highest voltage gain (~148) reported for a SiNW-based NOT gate, and the ring oscillator exhibits near rail-to-rail oscillation centered at 13.4 MHz. The static and dynamic characteristics of these NW devices indicate that these SiNW-based FET circuits are excellent candidates for various high-performance nanoelectronic applications. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  13. Multispectral absorptance from large-diameter InAsSb nanowire arrays in a single epitaxial growth on silicon

    Science.gov (United States)

    Robson, Mitchell; Azizur-Rahman, Khalifa M.; Parent, Daniel; Wojdylo, Peter; Thompson, David A.; LaPierre, Ray R.

    2017-12-01

    Vertical III-V nanowires are capable of resonant absorption at specific wavelengths by tuning the nanowire diameter, thereby exceeding the absorption of equivalent thin films. These properties may be exploited to fabricate multispectral infrared (IR) photodetectors, directly integrated with Si, without the need for spectral filters or vertical stacking of heterostructures as required in thin film devices. In this study, multiple InAsSb nanowire arrays were grown simultaneously on Si by molecular beam epitaxy with nanowire diameter controlled by the nanowire period (spacing between nanowires). This is the first such study of patterned InAsSb nanowires where control of nanowire diameter and multispectral absorption are demonstrated. The antimony flux was used to control axial and radial growth rates using a selective-area catalyst-free growth method, achieving large diameters, spanning 440–520 nm, which are necessary for optimum IR absorption. Fourier transform IR spectroscopy revealed IR absorptance peaks due to the HE11 resonance of the nanowire arrays in agreement with optical simulations. Due to the dependence of the HE11 resonance absorption on nanowire diameter, multispectral absorption was demonstrated in a single material system and a single epitaxial growth step without the need for bandgap tuning. This work demonstrates the potential of InAsSb nanowires for multispectral photodetectors and sensor arrays in the short-wavelength IR region.

  14. The Compatibility of Hepatocytes with Chemically Modified Porous Silicon with Reference to In Vitro Biosensors

    Science.gov (United States)

    Alvarez, Sara D.; Derfus, Austin M.; Schwartz, Michael P.; Bhatia, Sangeeta N.; Sailor, Michael J.

    2008-01-01

    Porous Si is a nanostructured material that is of interest for molecular and cell-based biosensing, drug delivery, and tissue engineering applications. Surface chemistry is an important factor determining the stability of porous Si in aqueous media, its affinity for various biomolecular species, and its compatibility with tissues. In this study, the attachment and viability of a primary cell type to porous Si samples containing various surface chemistries is reported, and the ability of the porous Si films to retain their optical reflectivity properties relevant to molecular biosensing is assessed. Four chemical species grafted to the porous Si surface are studied: silicon oxide (via ozone oxidation), dodecyl (via hydrosilylation with dodecene), undecanoic acid (via hydrosilylation with undecylenic acid), and oligo(ethylene) glycol (via hydrosilylation with undecylenic acid followed by an oligo(ethylene) glycol coupling reaction). Fourier Transform Infrared (FTIR) spectroscopy and contact angle measurements are used to characterize the surface. Adhesion and short-term viability of primary rat hepatocytes on these surfaces, with and without pre-adsorption of collagen type I, are assessed using vital dyes (calcein-AM and ethidium homodimer I). Cell viability on undecanoic acid-terminated porous Si, oxide-terminated porous Si, and oxide-terminated flat (non-porous) Si are monitored by quantification of albumin production over the course of 8 days. The stability of porous Si thin films after 8 days in cell culture is probed by measuring the optical interferometric reflectance spectra. Results show that hepatocytes adhere better to surfaces coated with collagen, and that chemical modification does not exert a deleterious effect on primary rat hepatocytes. The hydrosilylation chemistry greatly improves the stability of porous Si in contact with cultured primary cells while allowing cell coverage levels comparable to standard culture preparations on tissue culture

  15. Flexible semi-around gate silicon nanowire tunnel transistors with a sub-kT/q switch

    Science.gov (United States)

    Lee, Myeongwon; Jeon, Youngin; Kim, Minsuk; Kim, Sangsig

    2015-06-01

    Tunnel field-effect transistors (TFETs) with a subthreshold swing (SS) tunneling. In silicon (Si) channel materials, however, it still remains a challenge to obtain SS smaller than 60 mV/dec. In this study, we experimentally demonstrate the sub-60 mV/dec operation of a flexible semi-around gate TFET on a plastic substrate using Si nanowires (SiNWs) as the channel material. With the combined advantages of selectively thinned SiNW channels (width ˜ 15 nm and height ˜ 40 nm) and high-κ (Al2O3 ˜ 7 nm) gate dielectric, in conjunction with an abrupt degenerate source junction, the device with a channel length of ˜500 nm exhibits a minimal SS of ˜42 mV/dec at room temperature. Moreover, mechanical bendability of the device indicates that it has stable and good fatigue properties, providing an important step towards the realization of steep-slope switches for low-power and energy-efficient flexible electronics.

  16. An 8.68% efficiency chemically-doped-free graphene-silicon solar cell using silver nanowires network buried contacts.

    Science.gov (United States)

    Yang, Lifei; Yu, Xuegong; Hu, Weidan; Wu, Xiaolei; Zhao, Yan; Yang, Deren

    2015-02-25

    Graphene-silicon (Gr-Si) heterojunction solar cells have been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the high sheet resistance of chemical vapor deposited (CVD) Gr films is still the most important limiting factor for the improvement of the power conversion efficiency of Gr-Si solar cells, especially in the case of large device-active area. In this work, we have fabricated a novel transparent conductive film by hybriding a monolayer Gr film with silver nanowires (AgNWs) network soldered by the graphene oxide (GO) flakes. This Gr-AgNWs hybrid film exhibits low sheet resistance and larger direct-current to optical conductivity ratio, quite suitable for solar cell fabrication. An efficiency of 8.68% has been achieved for the Gr-AgNWs-Si solar cell, in which the AgNWs network acts as buried contacts. Meanwhile, the Gr-AgNWs-Si solar cells have much better stability than the chemically doped Gr-Si solar cells. These results show a new route for the fabrication of high efficient and stable Gr-Si solar cells.

  17. Controlled growth of MoS2 nanopetals on the silicon nanowire array using the chemical vapor deposition method

    Science.gov (United States)

    Chen, Shang-Min; Lin, Yow-Jon

    2018-01-01

    In order to get a physical/chemical insight into the formation of nanoscale semiconductor heterojunctions, MoS2 flakes are deposited on the silicon nanowire (SiNW) array by chemical vapor deposition (CVD). In this study, H2O2 treatment provides a favorable place where the formation of Sisbnd O bonds on the SiNW surfaces that play important roles (i.e., the nucleation centers, catalyst control centers or ;seeds;) can dominate the growth of MoS2 on the SiNWs. Using this configuration, the effect of a change in the S/MoO3 mass ratio (MS/MMoO3) on the surface morphology of MoS2 is studied. It is shown that an increase in the value of MS/MMoO3 leads to the increased nucleation rate, increasing the size of MoS2 nanopetals. This study provides valuable scientific information for directly CVD-grown edge-oriented MoS2/SiNWs heterojunctions for various nanoscale applications, including hydrogen evolution reaction and electronic and optoelectronic devices.

  18. Life cycle environmental impact of high-capacity lithium ion battery with silicon nanowires anode for electric vehicles.

    Science.gov (United States)

    Li, Bingbing; Gao, Xianfeng; Li, Jianyang; Yuan, Chris

    2014-01-01

    Although silicon nanowires (SiNW) have been widely studied as an ideal material for developing high-capacity lithium ion batteries (LIBs) for electric vehicles (EVs), little is known about the environmental impacts of such a new EV battery pack during its whole life cycle. This paper reports a life cycle assessment (LCA) of a high-capacity LIB pack using SiNW prepared via metal-assisted chemical etching as anode material. The LCA study is conducted based on the average U.S. driving and electricity supply conditions. Nanowastes and nanoparticle emissions from the SiNW synthesis are also characterized and reported. The LCA results show that over 50% of most characterized impacts are generated from the battery operations, while the battery anode with SiNW material contributes to around 15% of global warming potential and 10% of human toxicity potential. Overall the life cycle impacts of this new battery pack are moderately higher than those of conventional LIBs but could be actually comparable when considering the uncertainties and scale-up potential of the technology. These results are encouraging because they not only provide a solid base for sustainable development of next generation LIBs but also confirm that appropriate nanomanufacturing technologies could be used in sustainable product development.

  19. Engineering the thermal conductivity along an individual silicon nanowire by selective helium ion irradiation

    Science.gov (United States)

    Zhao, Yunshan; Liu, Dan; Chen, Jie; Zhu, Liyan; Belianinov, Alex; Ovchinnikova, Olga S.; Unocic, Raymond R.; Burch, Matthew J.; Kim, Songkil; Hao, Hanfang; Pickard, Daniel S.; Li, Baowen; Thong, John T. L.

    2017-06-01

    The ability to engineer the thermal conductivity of materials allows us to control the flow of heat and derive novel functionalities such as thermal rectification, thermal switching and thermal cloaking. While this could be achieved by making use of composites and metamaterials at bulk length-scales, engineering the thermal conductivity at micro- and nano-scale dimensions is considerably more challenging. In this work, we show that the local thermal conductivity along a single Si nanowire can be tuned to a desired value (between crystalline and amorphous limits) with high spatial resolution through selective helium ion irradiation with a well-controlled dose. The underlying mechanism is understood through molecular dynamics simulations and quantitative phonon-defect scattering rate analysis, where the behaviour of thermal conductivity with dose is attributed to the accumulation and agglomeration of scattering centres at lower doses. Beyond a threshold dose, a crystalline-amorphous transition was observed.

  20. Facile Passivation of Silicon Nanowires Array as Stable Photoanode in Aqueous Electrolytes.

    Science.gov (United States)

    Zhang, Xiaojie; He, Junhui

    2018-04-01

    We herein report a facile approach to passivate Si(100) nanowires (SiNWs) array by methylation and poly(3,4-ethylenedioxythiophene) (PEDOT) coating as stable photoanode in aqueous electrolytes. The photoanode was stable in both acid and base electrolytes. This facile approach deals with both the dangling bond and the anti-corrosion protection of SiNWs array. A combination of microstructural characterization, photoelectrochemical (PEC) measurements and electrochemical impedance spectroscopy (EIS) analysis were employed to confirm the methyl-terminated SiNWs/PEDOT (CH3-SiNWs/PEDOT) array structure and the role of methylation in enhancing the photocurrent of SiNWs array photoanode. It was found that the methylation increased the donor concentration and significantly decreased the charge transfer impedance (Rct), which means that the methylation facilitates majority transport and collection, and thus may account for the PEC enhancement.

  1. Engineering the thermal conductivity along an individual silicon nanowire by selective helium ion irradiation.

    Science.gov (United States)

    Zhao, Yunshan; Liu, Dan; Chen, Jie; Zhu, Liyan; Belianinov, Alex; Ovchinnikova, Olga S; Unocic, Raymond R; Burch, Matthew J; Kim, Songkil; Hao, Hanfang; Pickard, Daniel S; Li, Baowen; Thong, John T L

    2017-06-27

    The ability to engineer the thermal conductivity of materials allows us to control the flow of heat and derive novel functionalities such as thermal rectification, thermal switching and thermal cloaking. While this could be achieved by making use of composites and metamaterials at bulk length-scales, engineering the thermal conductivity at micro- and nano-scale dimensions is considerably more challenging. In this work, we show that the local thermal conductivity along a single Si nanowire can be tuned to a desired value (between crystalline and amorphous limits) with high spatial resolution through selective helium ion irradiation with a well-controlled dose. The underlying mechanism is understood through molecular dynamics simulations and quantitative phonon-defect scattering rate analysis, where the behaviour of thermal conductivity with dose is attributed to the accumulation and agglomeration of scattering centres at lower doses. Beyond a threshold dose, a crystalline-amorphous transition was observed.

  2. Effect of intravalley acoustic phonon scattering on quantum transport in multigate silicon nanowire metal-oxide-semiconductor field-effect transistors

    Science.gov (United States)

    Akhavan, Nima Dehdashti; Afzalian, Aryan; Lee, Chi-Woo; Yan, Ran; Ferain, Isabelle; Razavi, Pedram; Yu, Ran; Fagas, Giorgos; Colinge, Jean-Pierre

    2010-08-01

    In this paper we investigate the effects of intravalley acoustic phonon scattering on the quantum transport and on the electrical characteristics of multigate silicon nanowire metal-oxide-semiconductor field-effect transistors. We show that acoustic phonons cause a shift and broadening of the local DOS in the nanowire, which modifies the electrical characteristics of the device. The influence of scattering on off-state and on-state currents is investigated for different values of channel length. In the ballistic transport regime, source-to-drain tunneling current is predominant, whereas in the presence of acoustic phonons, diffusion becomes the dominant current transport mechanism. A three-dimensional quantum mechanical device simulator based on the nonequilibrium Green's function formalism in uncoupled-mode space has been developed to extract device parameters in the presence of electron-phonon interactions. Electron-phonon scattering is accounted for by adopting the self-consistent Born approximation and using the deformation potential theory.

  3. 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.

  4. Bottom-up and top-down fabrication of nanowire-based electronic devices: In situ doping of vapor liquid solid grown silicon nanowires and etch-dependent leakage current in InGaAs tunnel junctions

    Science.gov (United States)

    Kuo, Meng-Wei

    Semiconductor nanowires are important components in future nanoelectronic and optoelectronic device applications. These nanowires can be fabricated using either bottom-up or top-down methods. While bottom-up techniques can achieve higher aspect ratio at reduced dimension without having surface and sub-surface damage, uniform doping distributions with abrupt junction profiles are less challenging for top-down methods. In this dissertation, nanowires fabricated by both methods were systematically investigated to understand: (1) the in situ incorporation of boron (B) dopants in Si nanowires grown by the bottom-up vapor-liquid-solid (VLS) technique, and (2) the impact of plasma-induced etch damage on InGaAs p +-i-n+ nanowire junctions for tunnel field-effect transistors (TFETs) applications. In Chapter 2 and 3, the in situ incorporation of B in Si nanowires grown using silane (SiH4) or silicon tetrachloride (SiCl4) as the Si precursor and trimethylboron (TMB) as the p-type dopant source is investigated by I-V measurements of individual nanowires. The results from measurements using a global-back-gated test structure reveal nonuniform B doping profiles on nanowires grown from SiH4, which is due to simultaneous incorporation of B from nanowire surface and the catalyst during VLS growth. In contrast, a uniform B doping profile in both the axial and radial directions is achieved for TMBdoped Si nanowires grown using SiCl4 at high substrate temperatures. In Chapter 4, the I-V characteristics of wet- and dry-etched InGaAs p+-i-n+ junctions with different mesa geometries, orientations, and perimeter-to-area ratios are compared to evaluate the impact of the dry etch process on the junction leakage current properties. Different post-dry etch treatments, including wet etching and thermal annealing, are performed and the effectiveness of each is assessed by temperaturedependent I-V measurements. As compared to wet-etched control devices, dry-etched junctions have a significantly

  5. Nanowires of silicon carbide and 3D SiC/C nanocomposites with inverse opal structure

    International Nuclear Information System (INIS)

    Emelchenko, G.A.; Zhokhov, A.A.; Masalov, V.M.; Kudrenko, E.A.; Tereshenko, A.N.; Steinman, E.A.; Khodos, I.I.; Zinenko, V.I.; Agafonov, Yu.A.

    2011-01-01

    Synthesis, morphology, structural and optical characteristics of SiC NWs and SiC/C nanocomposites with an inverse opal lattice have been investigated. The samples were prepared by carbothermal reduction of silica (SiC NWs) and by thermo-chemical treatment of opal matrices (SiC/C) filled with carbon compounds which was followed by silicon dioxide dissolution. It was shown that the nucleation of SiC NWs occurs at the surface of carbon fibers felt. It was observed three preferred growth direction of the NWs: [111], [110] and [112]. HRTEM studies revealed the mechanism of the wires growth direction change. SiC/C- HRTEM revealed in the structure of the composites, except for silicon carbide, graphite and amorphous carbon, spherical carbon particles containing concentric graphite shells (onion-like particles).

  6. Strain-induced structural defects and their effects on the electrochemical performances of silicon core/germanium shell nanowire heterostructures.

    Science.gov (United States)

    Lin, Yung-Chen; Kim, Dongheun; Li, Zhen; Nguyen, Binh-Minh; Li, Nan; Zhang, Shixiong; Yoo, Jinkyoung

    2017-01-19

    We report on strain-induced structural defect formation in core Si nanowires of a Si/Ge core/shell nanowire heterostructure and the influence of the structural defects on the electrochemical performances in lithium-ion battery anodes based on Si/Ge core/shell nanowire heterostructures. The induced structural defects consisting of stacking faults and dislocations in the core Si nanowire were observed for the first time. The generation of stacking faults in the Si/Ge core/shell nanowire heterostructure is observed to prefer settling in either only the Ge shell region or in both the Ge shell and Si core regions and is associated with the increase of the shell volume fraction. The relaxation of the misfit strain in the [112] oriented core/shell nanowire heterostructure leads to subsequent gliding of Shockley partial dislocations, preferentially forming the twins. The observation of crossover of defect formation is of great importance for understanding heteroepitaxy in radial heterostructures at the nanoscale and for building three dimensional heterostructures for the various applications. Furthermore, the effect of the defect formation on the nanomaterial's functionality is investigated using electrochemical performance tests. The Si/Ge core/shell nanowire heterostructures enhance the gravimetric capacity of lithium ion battery anodes under fast charging/discharging rates compared to Si nanowires. However, the induced structural defects hamper lithiation of the Si/Ge core/shell nanowire heterostructure.

  7. Silicon nanowire heterostructures for advanced energy and environmental applications: a review

    Science.gov (United States)

    Ghosh, Ramesh; Giri, P. K.

    2017-01-01

    Semiconductor nanowires (NWs), in particular Si NWs, have attracted much attention in the last decade for their unique electronic properties and potential applications in several emerging areas. With the introduction of heterostructures (HSs) on NWs, new functionalities are obtained and the device performance is improved significantly in many cases. Due to the easy fabrication techniques, excellent optoelectronic properties and compatibility of forming HSs with different inorganic/organic materials, Si NW HSs have been utilized in various configurations and device architectures. Herein, we review the recent developments in Si NW HS-based devices including the fabrication techniques, properties (e.g., light emitting, antireflective, photocatalytic, electrical, photovoltaic, sensing etc) and related emerging applications in energy generation, conversion, storage, and environmental cleaning and monitoring. In particular, recent advances in Si NW HS-based solar photovoltaics, light-emitting devices, thermoelectrics, Li-ion batteries, supercapacitors, hydrogen generation, artificial photosynthesis, photocatalytic degradation of organic dyes in water treatment, chemical and gas sensors, biomolecular sensors for microbial monitoring etc have been addressed in detail. The problems and challenges in utilizing Si NW HSs in device applications and the key parameters to improve the device performance are pointed out. The recent trends in the commercial applications of Si NW HS-based devices and future outlook of the field are presented at the end.

  8. Non-Faradaic electrical impedimetric investigation of the interfacial effects of neuronal cell growth and differentiation on silicon nanowire transistors.

    Science.gov (United States)

    Lin, Shu-Ping; Vinzons, Lester U; Kang, Yu-Shan; Lai, Tung-Yen

    2015-05-13

    Silicon nanowire field-effect transistor (SiNW FET) devices have been interfaced with cells; however, their application for noninvasive, real-time monitoring of interfacial effects during cell growth and differentiation on SiNW has not been fully explored. Here, we cultured rat adrenal pheochromocytoma (PC12) cells, a type of neural progenitor cell, directly on SiNW FET devices to monitor cell adhesion during growth and morphological changes during neuronal differentiation for a period of 5-7 d. Monitoring was performed by measuring the non-Faradaic electrical impedance of the cell-SiNW FET system using a precision LCR meter. Our SiNW FET devices exhibited changes in impedance parameters during cell growth and differentiation because of the negatively charged cell membrane, seal resistance, and membrane capacitance at the cell/SiNW interface. It was observed that during both PC12 cell growth and neuronal differentiation, the impedance magnitude increased and the phase shifted to more negative values. However, impedance changes during cell growth already plateaued 3 d after seeding, while impedance changes continued until the last observation day during differentiation. Our results also indicate that the frequency shift to above 40 kHz after growth factor induction resulted from a larger coverage of cell membrane on the SiNWs due to distinctive morphological changes according to vinculin staining. Encapsulation of PC12 cells in a hydrogel scaffold resulted in a lack of trend in impedance parameters and confirmed that impedance changes were due to the cells. Moreover, cytolysis of the differentiated PC12 cells led to significant changes in impedance parameters. Equivalent electrical circuits were used to analyze the changes in impedance values during cell growth and differentiation. The technique employed in this study can provide a platform for performing investigations of growth-factor-induced progenitor cell differentiation.

  9. Comparative study of CNT, silicon nanowire and fullerene embedded multilayer high-k gate dielectric MOS memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Amretashis; Sarkar, Chandan Kumar [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700 032 (India); Requejo, Felix G, E-mail: amretashis@gmail.com [INIFTA, Departmento de Quimica and Departmento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC/67-1900, La Plata (Argentina)

    2011-10-12

    Here, we present a comparative theoretical study on stacked (multilayer) gate dielectric MOS memory devices, having a metallic/semiconducting carbon nanotube (CNT), silicon nanowire (Si NW) and fullerene (C60) embedded nitride layer acting as a floating gate. Two types of devices, one with HfO{sub 2}-SiO{sub 2} stack (stack-1) and the other with La{sub 2}O{sub 3}-SiO{sub 2} stack (stack-2) as the tunnel oxide were compared. We evaluated the effective barrier height, the dielectric constant and the effective electron mobility in the composite gate dielectric with the Maxwell-Garnett effective medium theory. Thereafter applying the WKB approximation, we simulated the Fowler-Nordheim (F-N) tunnelling/writing current and the direct tunnelling/leakage current in these devices. We evaluated the I-V characteristics, the charge decay and also the impact of CNT/Si NW aspect ratio and the volume fraction on the effective barrier height and the write voltage, respectively. We also simulated the write time, retention time and the erase time of these MOS devices. Based on the simulation results, it was concluded that the metallic CNT embedded stack-1 device offered the best performance in terms of higher F-N tunnelling current, lower direct tunnelling current and lesser write voltage and write time compared with the other devices. In case of direct tunnelling leakage and retention time it was found that the met CNT embedded stack-2 device showed better characteristics. For erasing, however, the C60 embedded stack-1 device showed the smallest erase time. When compared with earlier reports, it was seen that CNT, C60 and Si NW embedded devices all performed better than nanocrystalline Si embedded MOS non-volatile memories.

  10. Comparative study of CNT, silicon nanowire and fullerene embedded multilayer high-k gate dielectric MOS memory devices

    Science.gov (United States)

    Sengupta, Amretashis; Sarkar, Chandan Kumar; Requejo, Felix G.

    2011-10-01

    Here, we present a comparative theoretical study on stacked (multilayer) gate dielectric MOS memory devices, having a metallic/semiconducting carbon nanotube (CNT), silicon nanowire (Si NW) and fullerene (C60) embedded nitride layer acting as a floating gate. Two types of devices, one with HfO2-SiO2 stack (stack-1) and the other with La2O3-SiO2 stack (stack-2) as the tunnel oxide were compared. We evaluated the effective barrier height, the dielectric constant and the effective electron mobility in the composite gate dielectric with the Maxwell-Garnett effective medium theory. Thereafter applying the WKB approximation, we simulated the Fowler-Nordheim (F-N) tunnelling/writing current and the direct tunnelling/leakage current in these devices. We evaluated the I-V characteristics, the charge decay and also the impact of CNT/Si NW aspect ratio and the volume fraction on the effective barrier height and the write voltage, respectively. We also simulated the write time, retention time and the erase time of these MOS devices. Based on the simulation results, it was concluded that the metallic CNT embedded stack-1 device offered the best performance in terms of higher F-N tunnelling current, lower direct tunnelling current and lesser write voltage and write time compared with the other devices. In case of direct tunnelling leakage and retention time it was found that the met CNT embedded stack-2 device showed better characteristics. For erasing, however, the C60 embedded stack-1 device showed the smallest erase time. When compared with earlier reports, it was seen that CNT, C60 and Si NW embedded devices all performed better than nanocrystalline Si embedded MOS non-volatile memories.

  11. Silicon coupled-resonator optical-waveguide-based biosensors using light-scattering pattern recognition with pixelized mode-field-intensity distributions.

    Science.gov (United States)

    Wang, Jiawei; Yao, Zhanshi; Lei, Ting; Poon, Andrew W

    2014-12-18

    Chip-scale, optical microcavity-based biosensors typically employ an ultra-high-quality microcavity and require a precision wavelength-tunable laser for exciting the cavity resonance. For point-of-care applications, however, such a system based on measurements in the spectral domain is prone to equipment noise and not portable. An alternative microcavity-based biosensor that enables a high sensitivity in an equipment-noise-tolerant and potentially portable system is desirable. Here, we demonstrate the proof-of-concept of such a biosensor using a coupled-resonator optical-waveguide (CROW) on a silicon-on-insulator chip. The sensing scheme is based on measurements in the spatial domain, and only requires exciting the CROW at a fixed wavelength and imaging the out-of-plane elastic light-scattering intensity patterns of the CROW. Based on correlating the light-scattering intensity pattern at a probe wavelength with the light-scattering intensity patterns at the CROW eigenstates, we devise a pattern-recognition algorithm that enables the extraction of a refractive index change, Δn, applied upon the CROW upper-cladding from a calibrated set of correlation coefficients. Our experiments using an 8-microring CROW covered by NaCl solutions of different concentrations reveal a Δn of ~1.5 × 10(-4) refractive index unit (RIU) and a sensitivity of ~752 RIU(-1), with a noise-equivalent detection limit of ~6 × 10(-6) RIU.

  12. Experimental Observation of Quantum Confinement Effect in and Silicon Nanowire Field-Effect Transistors and Single-Electron/Hole Transistors Operating at Room Temperature

    Science.gov (United States)

    Suzuki, Ryota; Nozue, Motoki; Saraya, Takuya; Hiramoto, Toshiro

    2013-10-01

    The quantum confinement effect (QCE) in ultranarrow silicon nanowire channel field-effect transistors (FETs) as well as single-electron/hole transistors (SET/SHTs) operating at room temperature is intensively investigated for the optimization of device design and fabrication. By adopting a “shared channel” structure with the directions of and , a carrier-dependent QCE is systematically examined. It is found that nanowire pFETs exhibit a smaller threshold voltage (Vth) variability due to a weaker QCE, while nFETs and n/pFETs show comparable Vth variabilities coming from the QCE. It is also found that only SETs exhibit clear Coulomb oscillations in the case of the channel, suggesting the formation of higher tunnel barriers than SHTs. On the other hand, SHTs show undesirable multidot behavior in spite of their comparable QCEs for electrons and holes. It is concluded that -directed nanowire channel SETs and n/pFETs are suitable for the integration of CMOS and SETs.

  13. 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

    2013-04-01

    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.

  14. 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

  15. Detection of Ammonia-Oxidizing Bacteria (AOB) Using a Porous Silicon Optical Biosensor Based on a Multilayered Double Bragg Mirror Structure.

    Science.gov (United States)

    Zhang, Hongyan; Lv, Jie; Jia, Zhenhong

    2018-01-01

    We successfully demonstrate a porous silicon (PS) double Bragg mirror by electrochemical etching at room temperature as a deoxyribonucleic acid (DNA) label-free biosensor for detecting ammonia-oxidizing bacteria (AOB). Compared to various other one-dimension photonic crystal configurations of PS, the double Bragg mirror structure is quite easy to prepare and exhibits interesting optical properties. The width of high reflectivity stop band of the PS double Bragg mirror is about 761 nm with a sharp and deep resonance peak at 1328 nm in the reflectance spectrum, which gives a high sensitivity and distinguishability for sensing performance. The detection sensitivity of such a double Bragg mirror structure is illustrated through the investigation of AOB DNA hybridization in the PS pores. The redshifts of the reflectance spectra show a good linear relationship with both complete complementary and partial complementary DNA. The lowest detection limit for complete complementary DNA is 27.1 nM and the detection limit of the biosensor for partial complementary DNA is 35.0 nM, which provides the feasibility and effectiveness for the detection of AOB in a real environment. The PS double Bragg mirror structure is attractive for widespread biosensing applications and provides great potential for the development of optical applications.

  16. Chemical Gated Field Effect Transistor by Hybrid Integration of One-Dimensional Silicon Nanowire and Two-Dimensional Tin Oxide Thin Film for Low Power Gas Sensor.

    Science.gov (United States)

    Han, Jin-Woo; Rim, Taiuk; Baek, Chang-Ki; Meyyappan, M

    2015-09-30

    Gas sensors based on metal-oxide-semiconductor transistor with the polysilicon gate replaced by a gas sensitive thin film have been around for over 50 years. These are not suitable for the emerging mobile and wearable sensor platforms due to operating voltages and powers far exceeding the supply capability of batteries. Here we present a novel approach to decouple the chemically sensitive region from the conducting channel for reducing the drive voltage and increasing reliability. This chemically gated field effect transistor uses silicon nanowire for the current conduction channel with a tin oxide film on top of the nanowire serving as the gas sensitive medium. The potential change induced by the molecular adsorption and desorption allows the electrically floating tin oxide film to gate the silicon channel. As the device is designed to be normally off, the power is consumed only during the gas sensing event. This feature is attractive for the battery operated sensor and wearable electronics. In addition, the decoupling of the chemical reaction and the current conduction regions allows the gas sensitive material to be free from electrical stress, thus increasing reliability. The device shows excellent gas sensitivity to the tested analytes relative to conventional metal oxide transistors and resistive sensors.

  17. 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...

  18. Nanostructured Electrochemical Biosensors for Label-Free Detection of Water- and Food-Borne Pathogens.

    Science.gov (United States)

    Reta, Nekane; Saint, Christopher P; Michelmore, Andrew; Prieto-Simon, Beatriz; Voelcker, Nicolas H

    2018-02-21

    The emergence of nanostructured materials has opened new horizons in the development of next generation biosensors. Being able to control the design of the electrode interface at the nanoscale combined with the intrinsic characteristics of the nanomaterials engenders novel biosensing platforms with improved capabilities. The purpose of this review is to provide a comprehensive and critical overview of the latest trends in emerging nanostructured electrochemical biosensors. A detailed description and discussion of recent approaches to construct label-free electrochemical nanostructured electrodes is given with special focus on pathogen detection for environmental monitoring and food safety. This includes the use of nanoscale materials such as nanotubes, nanowires, nanoparticles, and nanosheets as well as porous nanostructured materials including nanoporous anodic alumina, mesoporous silica, porous silicon, and polystyrene nanochannels. These platforms may pave the way toward the development of point-of-care portable electronic devices for applications ranging from environmental analysis to biomedical diagnostics.

  19. A CMOS-Compatible Poly-Si Nanowire Device with Hybrid Sensor/Memory Characteristics for System-on-Chip Applications

    Directory of Open Access Journals (Sweden)

    Chia-Hua Ho

    2012-03-01

    Full Text Available This paper reports a versatile nano-sensor technology using “top-down” poly-silicon nanowire field-effect transistors (FETs in the conventional Complementary Metal-Oxide Semiconductor (CMOS-compatible semiconductor process. The nanowire manufacturing technique reduced nanowire width scaling to 50 nm without use of extra lithography equipment, and exhibited superior device uniformity. These n type polysilicon nanowire FETs have positive pH sensitivity (100 mV/pH and sensitive deoxyribonucleic acid (DNA detection ability (100 pM at normal system operation voltages. Specially designed oxide-nitride-oxide buried oxide nanowire realizes an electrically Vth-adjustable sensor to compensate device variation. These nanowire FETs also enable non-volatile memory application for a large and steady Vth adjustment window (>2 V Programming/Erasing window. The CMOS-compatible manufacturing technique of polysilicon nanowire FETs offers a possible solution for commercial System-on-Chip biosensor application, which enables portable physiology monitoring and in situ recording.

  20. A CMOS-compatible poly-Si nanowire device with hybrid sensor/memory characteristics for System-on-Chip applications.

    Science.gov (United States)

    Chen, Min-Cheng; Chen, Hao-Yu; Lin, Chia-Yi; Chien, Chao-Hsin; Hsieh, Tsung-Fan; Horng, Jim-Tong; Qiu, Jian-Tai; Huang, Chien-Chao; Ho, Chia-Hua; Yang, Fu-Liang

    2012-01-01

    This paper reports a versatile nano-sensor technology using "top-down" poly-silicon nanowire field-effect transistors (FETs) in the conventional Complementary Metal-Oxide Semiconductor (CMOS)-compatible semiconductor process. The nanowire manufacturing technique reduced nanowire width scaling to 50 nm without use of extra lithography equipment, and exhibited superior device uniformity. These n type polysilicon nanowire FETs have positive pH sensitivity (100 mV/pH) and sensitive deoxyribonucleic acid (DNA) detection ability (100 pM) at normal system operation voltages. Specially designed oxide-nitride-oxide buried oxide nanowire realizes an electrically V(th)-adjustable sensor to compensate device variation. These nanowire FETs also enable non-volatile memory application for a large and steady V(th) adjustment window (>2 V Programming/Erasing window). The CMOS-compatible manufacturing technique of polysilicon nanowire FETs offers a possible solution for commercial System-on-Chip biosensor application, which enables portable physiology monitoring and in situ recording.

  1. Fabrication and photoelectrochemical properties of silicon nanowires/g-C{sub 3}N{sub 4} core/shell arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhen [Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Institute of Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Ma, Ge [Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Chen, Zhihong, E-mail: chenzhihong1227@sina.com [Shenyang Institute of Automation, Guangzhou, Chinese Academy of Sciences, Guangzhou 511458 (China); Zhang, Yongguang [Research Institute for Energy Equipment Materials, Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology, Hebei University of Technology, Tianjin 300130 (China); Zhang, Zhe [Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Gao, Jinwei [Institute of Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Meng, Qingguo; Yuan, Mingzhe [Shenyang Institute of Automation, Guangzhou, Chinese Academy of Sciences, Guangzhou 511458 (China); Wang, Xin, E-mail: wangxin@scnu.edu.cn [Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Liu, Jun-ming [Institute of Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China); Zhou, Guofu [Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province (China)

    2017-02-28

    Highlights: • A novel Silicon Nanowires/g-C{sub 3}N{sub 4} core/shell arrays photoanode prepared by a mild and inexpensive metal-catalyzed electroless etching (MCEE) process followed by liquid atomic layer deposition (LALD), wiich is a facile and low-cost method. • In comparison with FTO/g-C{sub 3}N{sub 4} and Si NWs samples, the Si NWs/g-C{sub 3}N{sub 4} samples showed significantly enhanced photocurrent which could be attributed to the SiNWs-based core/shell structure. • A systematical PEC mechanism of the Si NWs/g-C{sub 3}N{sub 4} was proposed is this manuscript. - Abstract: A photoelectrochemical (PEC) cell made of metal-free carbon nitride (g-C{sub 3}N{sub 4}) @siliconnanowire(Si NW) arrays (denoted as Si NWs/g-C{sub 3}N{sub 4}) is presented in this work. The as-prepared photoelectrodes with different mass contents of g-C{sub 3}N{sub 4} have been synthesized via a metal-catalyzed electroless etching (MCEE), liquid atomic layer deposition (LALD) and annealing methods. The amount of g-C{sub 3}N{sub 4} on the Si NW arrays can be controlled by tuning the concentration of the cyanamide solution used in the LALD procedure. The dense and vertically aligned Si NWs/g-C{sub 3}N{sub 4} core/shell nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In comparison with FTO/g-C{sub 3}N{sub 4} and Si NW samples, the Si NWs/g-C{sub 3}N{sub 4} samples showed significantly enhanced photocurrents over the entire potential sweep range. Electrochemical impedance spectroscopy (EIS) was conducted to investigate the properties of the charge transfer process, and the results indicated that the enhanced PEC performance may be due to the increased photo-generated interfacial charge transfer between the Si NWs and g-C{sub 3}N{sub 4}. The photocurrent density reached 45 μA/cm{sup 2} under 100 mW/cm{sup 2} (AM 1.5 G) illumination at 0 V (vs. Pt) in neutral Na{sub 2}SO{sub 4} solution (pH ∼ 7

  2. Nanowire Growth for Photovoltaics

    DEFF Research Database (Denmark)

    Holm, Jeppe Vilstrup

    consisting of a single, vertical, gallium arsenide(GaAs) nanowire grown on silicon with a radial p-i-n-junction. The average concentration was ~8, and the peak concentration was ~12. By increasing the number of junctions in solar cells, they can extract more energy per absorbed photon. In ideal multi...... of the nanowires, some of which were removed from their growth substrate and turned into single nanowire solar cells (SNWSC). The best device showed a conversion efficiency of 6.8% under 1.5AMG 1-sun illumination. In order to improve the efficiency a surface passivating shell consisting of highly doped, wide......Solar cells commercial success is based on an efficiency/cost calculation. Nanowire solar cells is one of the foremost candidates to implement third generation photo voltaics, which are both very efficient and cheap to produce. This thesis is about our progress towards commercial nanowire solar...

  3. Semiconductor Nanowires: Epitaxy and Applications

    OpenAIRE

    Mårtensson, Thomas

    2008-01-01

    Semiconductor nanowires are nanoscale objects formed by bottom-up synthesis. In recent years their unique properties have been exploited in fields such as electronics, photonics, sensors and the life sciences. In this work, the epitaxial growth of nanowires and their applications were studied. Heteroepitaxial growth of III-V nanowires on silicon substrates was demonstrated. This may enable direct band gap materials for optoelectronic devices, as well as high-mobility, low-contact resis...

  4. 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.

  5. Selective formation of tungsten nanowires

    Directory of Open Access Journals (Sweden)

    Bien Daniel

    2011-01-01

    Full Text Available Abstract We report on a process for fabricating self-aligned tungsten (W nanowires with polycrystalline silicon core. Tungsten nanowires as thin as 10 nm were formed by utilizing polysilicon sidewall transfer technology followed by selective deposition of tungsten by chemical vapor deposition (CVD using WF6 as the precursor. With selective CVD, the process is self-limiting whereby the tungsten formation is confined to the polysilicon regions; hence, the nanowires are formed without the need for lithography or for additional processing. The fabricated tungsten nanowires were observed to be perfectly aligned, showing 100% selectivity to polysilicon and can be made to be electrically isolated from one another. The electrical conductivity of the nanowires was characterized to determine the effect of its physical dimensions. The conductivity for the tungsten nanowires were found to be 40% higher when compared to doped polysilicon nanowires of similar dimensions.

  6. Surface Emitting, High Efficiency Near-Vacuum Ultraviolet Light Source with Aluminum Nitride Nanowires Monolithically Grown on Silicon.

    Science.gov (United States)

    Zhao, S; Djavid, M; Mi, Z

    2015-10-14

    To date, it has remained challenging to realize electrically injected light sources in the vacuum ultraviolet wavelength range (∼200 nm or shorter), which are important for a broad range of applications, including sensing, surface treatment, and photochemical analysis. In this Letter, we have demonstrated such a light source with molecular beam epitaxially grown aluminum nitride (AlN) nanowires on low cost, large area Si substrate. Detailed angle dependent electroluminescence studies suggest that, albeit the light is TM polarized, the dominant light emission direction is from the nanowire top surface, that is, along the c axis, due to the strong light scattering effect. Such an efficient surface emitting device was not previously possible using conventional c-plane AlN planar structures. The AlN nanowire LEDs exhibit an extremely large electrical efficiency (>85%), which is nearly ten times higher than the previously reported AlN planar devices. Our detailed studies further suggest that the performance of AlN nanowire LEDs is predominantly limited by electron overflow. This study provides important insight on the fundamental emission characteristics of AlN nanowire LEDs and also offers a viable path to realize an efficient surface emitting near-vacuum ultraviolet light source through direct electrical injection.

  7. 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

    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 observed from PSiNW samples etched using the optimum hydrofluoric acid (HF) concentration. The strongest photoluminescence (PL) signal has been measured from samples etched with 4.8 M of HF, beyond which a significant decreasing in PL emission intensity has been observed. A qualitative model is proposed for the formation of PSiNWs in the presence of Ag catalyst. This model affirms our observations in PL enhancement for samples etched using HF <4.8 M and the eventual PL reduction for samples etched beyond 4.8 M of HF concentration. The enhancement in PL signals has been associated to the formation of PSiNWs and the quantum confinement effect in the Si nanocrystallites. Compared to PSiNWs without Si-O x, the HF treated samples exhibited significant blue PL peak shift of 100 nm. This effect has been correlated to the formation of defect states in the surface oxide. PSiNWs fabricated using the electroless etching method can find useful applications in optical sensors and as anti-reflection layer in silicon-based solar cells. © 2012 American Institute of Physics.

  8. Effects of silicon nanowires (SiNWs) contents on the optical and dielectric properties of poly(3-hexylthiophene):SiNWs nanocomposites

    Science.gov (United States)

    Saidi, Hamza; Walid, Aloui; Bouazizi, Abdelaziz; Herrero, Beatriz Romero; Saidi, Faouzi

    2017-08-01

    In this study, we investigated the dependency of the optical and electrical proprieties of poly(3-hexylthiophene):silicon nanowires (P3HT:SiNWs) nanocomposites on the concentration of SiNWs based on photoluminescence (PL) and impedance spectroscopy. The PL spectra indicated the presence of charge transfer at low concentrations of SiNWs. The effects of the SiNWs contents on the loss mechanism were determined based on permittivity measurements, which were related to the distribution of the SiNWs contents on the polymer backbones, as well as being correlated with the PL and conductance results. The imaginary part of the impedance exhibited a high relaxation frequency attributable to Maxwell-Wagner polarization, where the extracted relaxation time was in the range of milliseconds. The Cole-Cole diagram had an excellent fit via the equivalent circuit, which incorporated the chemical capacitance Cμ, contact electrical resistance Rs, and recombination resistance Rp.

  9. Ultra-high-speed optical serial-to-parallel data conversion by time-domain optical Fourier transformation in a silicon nanowire.

    Science.gov (United States)

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Hu, Hao; Ji, Hua; Lillieholm, Mads; Galili, Michael; Clausen, Anders T; Pu, Minhao; Yvind, Kresten; Hvam, Jørn M; Jeppesen, Palle; Oxenløwe, Leif K

    2011-12-12

    We demonstrate conversion from 64 × 10 Gbit/s optical time-division multiplexed (OTDM) data to dense wavelength division multiplexed (DWDM) data with 25 GHz spacing. The conversion is achieved by time-domain optical Fourier transformation (OFT) based on four-wave mixing (FWM) in a 3.6 mm long silicon nanowire. A total of 40 out of 64 tributaries of a 64 × 10 Gbit/s OTDM-DPSK data signal are simultaneously converted with a bit-error rate (BER) performance below the 2 × 10(-3) FEC limit. Using a 50 m long highly nonlinear fiber (HNLF) for higher FWM conversion efficiency, 43 tributaries of a 64 × 10 Gbit/s OTDM-OOK data signal are converted with error-free performance (BER<10(-9)). © 2011 Optical Society of America

  10. Microwave- assisted Rapid Self- Assembly of Lamellar Forming Poly (styrene-b- lactic acid) (PS-b-PLA) Block Copolymer for Fabrication of Silicon Nanowires

    Science.gov (United States)

    Mokarian-Tabari, Parvaneh; Cummins, Cian; Rasappa, Sozaraj; Holmes, Justin D.; Morris, Michael M.

    2013-03-01

    Photolithography has been a fundamental process in the production of integrated circuits, but it is reaching its physical limit for generating ultra-small feature sizes. Block copolymers have a great potential as mask templates for fabricating nano features. Although ordered sub 20 nm features utilising BCPs have been achieved, lengthy annealing times (hours to days) are currently employed. Here we use microwave annealing, a new emerging technique, to achieve lateral phase separation in a lamellar forming PS-b-PLA. Having optimised the microwave conditions such as power, temperature, anneal holding time, solvents etc, a long range order line pattern was formed in less than two minutes on Si, Ge and Al substrates. The etched pattern (PLA removed by Ar/O2 RIE) was transferred to silicon substrate resulting in 18nm Si nanowires.

  11. A reliable extraction method for source and drain series resistances in silicon nanowire metal-oxide-semiconductor field-effect-transistors (MOSFETs) based on radio-frequency analysis.

    Science.gov (United States)

    Hwa, Jae Hwa; Yoon, Young Jun; Lee, Hwan Gi; Yoo, Gwan Min; Cho, Eou-Sik; Cho, Seongjae; Lee, Jung-Hee; Kang, In Man

    2014-11-01

    This paper presents a new extraction method for source and drain (S/D) series resistances of silicon nanowire (SNW) metal-oxide-semiconductor field-effect transistors (MOSFETs) based on small-signal radio-frequency (RF) analysis. The proposed method can be applied to the extraction of S/D series resistances for SNW MOSFETs with finite off-state channel resistance as well as gate bias-dependent on-state resistive components realized by 3-dimensional (3-D) device simulation. The series resistances as a function of frequency and gate voltage are presented and compared with the results obtained by an existing method with infinite off-state channel resistance model. The accuracy of the newly proposed parameter extraction method has been successfully verified by Z22- and Y-parameters up to 100 GHz operation frequency.

  12. Biosensors and environmental health

    National Research Council Canada - National Science Library

    Preedy, Victor R; Patel, Vinood B

    2012-01-01

    ..., bacterial biosensors, antibody-based biosensors, enzymatic, amperometric and electrochemical aspects, quorum sensing, DNA-biosensors, cantilever biosensors, bioluminescence and other methods and applications...

  13. Facile Five-Step Heteroepitaxial Growth of GaAs Nanowires on Silicon Substrates and the Twin Formation Mechanism.

    Science.gov (United States)

    Yao, Maoqing; Sheng, Chunyang; Ge, Mingyuan; Chi, Chun-Yung; Cong, Sen; Nakano, Aiichiro; Dapkus, P Daniel; Zhou, Chongwu

    2016-02-23

    Monolithic integration of III-V semiconductors with Si has been pursued for some time in the semiconductor industry. However, the mismatch of lattice constants and thermal expansion coefficients represents a large technological challenge for the heteroepitaxial growth. Nanowires, due to their small lateral dimension, can relieve strain and mitigate dislocation formation to allow single-crystal III-V materials to be grown on Si. Here, we report a facile five-step heteroepitaxial growth of GaAs nanowires on Si using selective area growth (SAG) in metalorganic chemical vapor deposition, and we further report an in-depth study on the twin formation mechanism. Rotational twin defects were observed in the nanowire structures and showed strong dependence on the growth condition and nanowire size. We adopt a model of faceted growth to demonstrate the formation of twins during growth, which is well supported by both a transmission electron microscopy study and simulation based on nucleation energetics. Our study has led to twin-free segments in the length up to 80 nm, a significant improvement compared to previous work using SAG. The achievements may open up opportunities for future functional III-V-on-Si heterostructure devices.

  14. Optical biosensors.

    Science.gov (United States)

    Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

    2016-06-30

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  15. Silicon photomultiplier (SPM) detection of low-level bioluminescence for the development of deployable whole-cell biosensors: possibilities and limitations.

    Science.gov (United States)

    Li, Huaqing; Lopes, Nicholas; Moser, Scott; Sayler, Gary; Ripp, Steven

    2012-03-15

    Whole-cell bacterial bioreporters await miniaturized photon counting modules with high sensitivity and robust compatible hardware to fulfill their promise of versatile, on-site biosensor functionality. In this study, we explore the photon counting readout properties of the silicon photomultiplier (SPM) with a thermoelectric cooler and the possibilities of detecting low-level bioluminescent signals. Detection performance was evaluated through a simulated LED light source and the bioluminescence produced by the genetically engineered Pseudomonas fluorescens bacterial bioreporter 5RL. Compared with the conventional photomultiplier tube (PMT), the results revealed that the cooled SPM exhibits a wider linear response to inducible substrate concentrations (salicylate) ranging from 250 to 5000 ppb. Although cooling of the SPM lowered dark count rates and improved the minimum detectable signal, and the application of a digital filter enhanced the signal-to-noise ratio, the detection of very low light signals is still limited and remains a challenge in the design of compact photon counting systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Photoelectrochemistry of Semiconductor Nanowire Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mallouk, Thomas E; Redwing, Joan M

    2009-11-10

    This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.

  17. Delivery of Cisplatin Anti-Cancer Drug from Carbon, Boron Nitride, and Silicon Carbide Nanotubes Forced by Ag-Nanowire: A Comprehensive Molecular Dynamics Study.

    Science.gov (United States)

    Mehrjouei, Esmat; Akbarzadeh, Hamed; Shamkhali, Amir Nasser; Abbaspour, Mohsen; Salemi, Sirous; Abdi, Pooya

    2017-07-03

    In this work, liberation of cisplatin molecules from interior of a nanotube due to entrance of an Ag-nanowire inside it was simulated by classical molecular dynamics method. The aim of this simulation was investigation on the effects of diameter, chirality, and composition of the nanotube, as well as the influence of temperature on this process. For this purpose, single walled carbon, boron nitride, and silicon carbide nanotube were considered. In order for a more concise comparison of the results, a new parameter namely efficiency of drug release, was introduced. The results demonstrated that the efficiency of drug release is sensitive to its adsorption on outer surface of the nanotube. Moreover, this efficiency is also sensitive to the nanotube composition and its diameter. For the effect of nanotube composition, the results indicated that silicon carbide nanotube has the least efficiency for drug release, due to its strong drug-nanotube. Also, the most important acting forces on drug delivery are van der Waals interactions. Finally, the kinetic of drug release is fast and is not related to the structural parameters of the nanotube and temperature, significantly.

  18. Highly uniform ultraviolet-A quantum-confined AlGaN nanowire LEDs on metal/silicon with a TaN interlayer

    KAUST Repository

    Priante, Davide

    2017-11-02

    In this paper, we describe ultraviolet-A (UV-A) light-emitting diodes (LEDs) emitting at 325 nm based on a highly uniform structure of quantum-confined AlGaN quantum-disk nanowires (NWs). By incorporating a 20 nm TaN interlayer between a Ti pre-orienting layer and the silicon substrate, we eliminated the potential barrier for carrier injection and phonon transport, and inhibited the formation of interfacial silicide that led to device failure. Compared to previous reports on metal substrate, we achieved a 16 × reduction in root-mean-square (RMS) roughness, from 24 nm to 1.6 nm, for the samples with the Ti/TaN metal-bilayer, owing to the effective diffusion barrier characteristic of TaN. This was confirmed using energy dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS). We achieved a considerable increase in the injection current density (up to 90 A/cm2) compared to our previous studies, and an optical power of 1.9 μW for the 0.5 × 0.5 mm2 NWs-LED. This work provides a feasible pathway for both a reliable and stable UV-A device operation at elevated current injection, and eventually towards low-cost production of UV devices, leveraging on the scalability of silicon substrates.

  19. III-nitride disk-in-nanowire 1.2 μm monolithic diode laser on (001)silicon

    KAUST Repository

    Hazari, Arnab

    2015-11-12

    III-nitride nanowirediodeheterostructures with multiple In0.85Ga0.15N disks and graded InGaN mode confining regions were grown by molecular beam epitaxy on (001)Si substrates. The aerial density of the 60 nm nanowires is ∼3 × 1010 cm−2. A radiative recombination lifetime of 1.84 ns in the disks is measured by time-resolved luminescence measurements. Edge-emitting nanowire lasers have been fabricated and characterized. Measured values of Jth, T0, and dg/dn in these devices are 1.24 kA/cm2, 242 K, and 5.6 × 10−17 cm2, respectively. The peak emission is observed at ∼1.2 μm.

  20. Amorphous SiO {sub x} nanowires grown on silicon (100) substrates via rapid thermal process of nanodiamond films

    Energy Technology Data Exchange (ETDEWEB)

    Liang Xingbo [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Wang Lei [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yang Deren [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)]. E-mail: mseyang@zju.edu.cn

    2006-05-01

    Rapid thermal process (RTP) has been carried out on the deposited nanocrystalline diamond (NCD) films. The RTP treatments performed at 800 and 1200 deg. C have been shown to exert prominent influence on the morphology and structure of the NCD films. The loss of material at grain boundaries has been observed at both 800 and 1200 deg. C RTP treatments. Large-scale amorphous SiO {sub x} nanowires with diameters of 30-50 nm and length up to 10 {mu}m were synthesized after RTP treatment at 1200 deg. C for 60 s. The synthesized nanowires were characterized in detail by scanning electron microscopy, transmission electron microscopy, selected area electron diffraction and energy-dispersed X-ray spectrometry analysis. A possible growth mechanism has been proposed to explain the observed phenomenon.

  1. Modeling of subthreshold characteristics of short channel junctionless cylindrical surrounding-gate nanowire metal–oxide–silicon field effect transistors

    International Nuclear Information System (INIS)

    Jin, Xiaoshi; Liu, Xi; Lee, Jung-Hee; Lee, Jong-Ho

    2014-01-01

    A subthreshold model of short-channel junctionless field effect transistors with cylindrical surrounding-gate nanowire structure has been proposed. It was based on an approximated solution of two-dimensional Poisson's equation. The derivation of this model was introduced and the accuracy of the proposed models have been verified by comparison with both previous models and the SILVACO Atlas TCAD simulation results, which show good agreement. (paper)

  2. Single crystalline PtSi nanowires, PtSi/Si/PtSi nanowire heterostructures, and nanodevices.

    Science.gov (United States)

    Lin, Yung-Chen; Lu, Kuo-Chang; Wu, Wen-Wei; Bai, Jingwei; Chen, Lih J; Tu, K N; Huang, Yu

    2008-03-01

    We report the formation of PtSi nanowires, PtSi/Si/PtSi nanowire heterostructures, and nanodevices from such heterostructures. Scanning electron microscopy studies show that silicon nanowires can be converted into PtSi nanowires through controlled reactions between lithographically defined platinum pads and silicon nanowires. High-resolution transmission electron microscopy studies show that PtSi/Si/PtSi heterostructure has an atomically sharp interface with epitaxial relationships of Si[110]//PtSi[010] and Si(111)//PtSi(101). Electrical measurements show that the pure PtSi nanowires have low resistivities approximately 28.6 microOmega.cm and high breakdown current densities>1x10(8) A/cm2. Furthermore, using single crystal PtSi/Si/PtSi nanowire heterostructures with atomically sharp interfaces, we have fabricated high-performance nanoscale field-effect transistors from intrinsic silicon nanowires, in which the source and drain contacts are defined by the metallic PtSi nanowire regions, and the gate length is defined by the Si nanowire region. Electrical measurements show nearly perfect p-channel enhancement mode transistor behavior with a normalized transconductance of 0.3 mS/microm, field-effect hole mobility of 168 cm2/V.s, and on/off ratio>10(7), demonstrating the best performing device from intrinsic silicon nanowires.

  3. 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.

  4. Regenerative electronic biosensors using supramolecular approaches

    NARCIS (Netherlands)

    Duan, X.; Rajan, N.; Routenberg, D.; Huskens, Jurriaan; Reed, M.

    2013-01-01

    A supramolecular interface for Si nanowire FETs has been developed with the aim of creating regenerative electronic biosensors. The key to the approach is Si-NWs functionalized with β-cyclodextrin (β-CD), to which receptor moieties can be attached with an orthogonal supramolecular linker. Here we

  5. Protein adsorption/desorption and antibody binding stoichiometry on silicon interferometric biosensors examined with TOF-SIMS

    KAUST Repository

    Gajos, Katarzyna

    2018-03-05

    Time-of-flight secondary ion mass spectrometry has been employed to examine, with biomolecular discrimination, sensing arm areas (20 μm x 600 μm) of integrated onto silicon chips Mach-Zehnder interferometers aiming to optimize their biofunctionalization with regard to indirect immunochemical (competitive) detection of ochratoxin A. Sensing areas are examined after: modification with (3-aminopropyl)triethoxysilane, spotting of OTA-ovalbumin conjugate (probe) from solutions with different concentration, blocking with bovine serum albumin, reaction with OTA-specific mouse monoclonal antibody followed by goat anti-mouse IgG secondary antibody. Component mass loadings of all proteins involved in immunodetection are determined from TOF-SIMS micro-analysis combined with ellipsometry of planar surfaces. These data show that partial desorption of surface-bound probe and blocking protein takes place upon primary immunoreaction to a degree that depends on probe concentration in spotting solution. Taking into account this desorption, apparent binding stoichiometry of both antibodies in immune complexes formed onto chip surface is determined more accurately than the respective evaluation based on real-time sensor response. In addition, mass loadings for probe and secondary antibody is observed to saturate for optimum probe concentrations. Also, principal component analysis of TOF-SIMS data could resolve both immunoreactions and biofunctionalization and discriminate surfaces prepared with optimum probe concentrations from those prepared using suboptimum ones.

  6. 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.

  7. 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...

  8. High Area Capacity Lithium-Sulfur Full-cell Battery with Prelitiathed Silicon Nanowire-Carbon Anodes for Long Cycling Stability

    Science.gov (United States)

    Krause, Andreas; Dörfler, Susanne; Piwko, Markus; Wisser, Florian M.; Jaumann, Tony; Ahrens, Eike; Giebeler, Lars; Althues, Holger; Schädlich, Stefan; Grothe, Julia; Jeffery, Andrea; Grube, Matthias; Brückner, Jan; Martin, Jan; Eckert, Jürgen; Kaskel, Stefan; Mikolajick, Thomas; Weber, Walter M.

    2016-01-01

    We show full Li/S cells with the use of balanced and high capacity electrodes to address high power electro-mobile applications. The anode is made of an assembly comprising of silicon nanowires as active material densely and conformally grown on a 3D carbon mesh as a light-weight current collector, offering extremely high areal capacity for reversible Li storage of up to 9 mAh/cm2. The dense growth is guaranteed by a versatile Au precursor developed for homogenous Au layer deposition on 3D substrates. In contrast to metallic Li, the presented system exhibits superior characteristics as an anode in Li/S batteries such as safe operation, long cycle life and easy handling. These anodes are combined with high area density S/C composite cathodes into a Li/S full-cell with an ether- and lithium triflate-based electrolyte for high ionic conductivity. The result is a highly cyclable full-cell with an areal capacity of 2.3 mAh/cm2, a cyclability surpassing 450 cycles and capacity retention of 80% after 150 cycles (capacity loss <0.4% per cycle). A detailed physical and electrochemical investigation of the SiNW Li/S full-cell including in-operando synchrotron X-ray diffraction measurements reveals that the lower degradation is due to a lower self-reduction of polysulfides after continuous charging/discharging. PMID:27319783

  9. High Area Capacity Lithium-Sulfur Full-cell Battery with Prelitiathed Silicon Nanowire-Carbon Anodes for Long Cycling Stability

    Science.gov (United States)

    Krause, Andreas; Dörfler, Susanne; Piwko, Markus; Wisser, Florian M.; Jaumann, Tony; Ahrens, Eike; Giebeler, Lars; Althues, Holger; Schädlich, Stefan; Grothe, Julia; Jeffery, Andrea; Grube, Matthias; Brückner, Jan; Martin, Jan; Eckert, Jürgen; Kaskel, Stefan; Mikolajick, Thomas; Weber, Walter M.

    2016-06-01

    We show full Li/S cells with the use of balanced and high capacity electrodes to address high power electro-mobile applications. The anode is made of an assembly comprising of silicon nanowires as active material densely and conformally grown on a 3D carbon mesh as a light-weight current collector, offering extremely high areal capacity for reversible Li storage of up to 9 mAh/cm2. The dense growth is guaranteed by a versatile Au precursor developed for homogenous Au layer deposition on 3D substrates. In contrast to metallic Li, the presented system exhibits superior characteristics as an anode in Li/S batteries such as safe operation, long cycle life and easy handling. These anodes are combined with high area density S/C composite cathodes into a Li/S full-cell with an ether- and lithium triflate-based electrolyte for high ionic conductivity. The result is a highly cyclable full-cell with an areal capacity of 2.3 mAh/cm2, a cyclability surpassing 450 cycles and capacity retention of 80% after 150 cycles (capacity loss physical and electrochemical investigation of the SiNW Li/S full-cell including in-operando synchrotron X-ray diffraction measurements reveals that the lower degradation is due to a lower self-reduction of polysulfides after continuous charging/discharging.

  10. Isolation and Identification of Post-Transcriptional Gene Silencing-Related Micro-RNAs by Functionalized Silicon Nanowire Field-effect Transistor

    Science.gov (United States)

    Chen, Kuan-I.; Pan, Chien-Yuan; Li, Keng-Hui; Huang, Ying-Chih; Lu, Chia-Wei; Tang, Chuan-Yi; Su, Ya-Wen; Tseng, Ling-Wei; Tseng, Kun-Chang; Lin, Chi-Yun; Chen, Chii-Dong; Lin, Shih-Shun; Chen, Yit-Tsong

    2015-11-01

    Many transcribed RNAs are non-coding RNAs, including microRNAs (miRNAs), which bind to complementary sequences on messenger RNAs to regulate the translation efficacy. Therefore, identifying the miRNAs expressed in cells/organisms aids in understanding genetic control in cells/organisms. In this report, we determined the binding of oligonucleotides to a receptor-modified silicon nanowire field-effect transistor (SiNW-FET) by monitoring the changes in conductance of the SiNW-FET. We first modified a SiNW-FET with a DNA probe to directly and selectively detect the complementary miRNA in cell lysates. This SiNW-FET device has 7-fold higher sensitivity than reverse transcription-quantitative polymerase chain reaction in detecting the corresponding miRNA. Next, we anchored viral p19 proteins, which bind the double-strand small RNAs (ds-sRNAs), on the SiNW-FET. By perfusing the device with synthesized ds-sRNAs of different pairing statuses, the dissociation constants revealed that the nucleotides at the 3‧-overhangs and pairings at the terminus are important for the interactions. After perfusing the total RNA mixture extracted from Nicotiana benthamiana across the device, this device could enrich the ds-sRNAs for sequence analysis. Finally, this bionanoelectronic SiNW-FET, which is able to isolate and identify the interacting protein-RNA, adds an additional tool in genomic technology for the future study of direct biomolecular interactions.

  11. Binding of p-mercaptobenzoic acid and adenine to gold-coated electroless etched silicon nanowires studied by surface-enhanced Raman scattering.

    Science.gov (United States)

    Mohaček-Grošev, Vlasta; Gebavi, Hrvoje; Bonifacio, Alois; Sergo, Valter; Daković, Marko; Bajuk-Bogdanović, Danica

    2018-04-10

    Modern diagnostic tools ever aim to reduce the amount of analyte and the time needed for obtaining the result. Surface-enhanced Raman spectroscopy is a method that could satisfy both of these requirements, provided that for each analyte an adequate substrate is found. Here we demonstrate the ability of gold-sputtered silicon nanowires (SiNW) to bind p-mercaptobenzoic acid in 10 -3 , 10 -4 and 10 -5 M and adenine in 30 and 100μM concentrations. Based on the normal mode analysis, presented here for the first time, the binding of p-mercaptobenzoic acid is deduced. The intensity enhancement of the 1106cm -1 band is explained by involvement of the CS stretching deformation, and the appearance of the broad 300cm -1 band attributed to SAu stretching mode. Adenine SERS spectra demonstrate the existence of the 7H tautomer since the strongest band observed is at 736cm -1 . The adenine binding is likely to occur in several ways, because the number of observed bands in the 1200-1600cm -1 interval exceeds the number of observed bands in the normal Raman spectrum of the free molecule. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Optimization of the thermoelectric power factors in 50-nm n- and p-type silicon nanowires by varying the doping concentration

    Science.gov (United States)

    Kim, Soojung; Kim, Jaehyeon; Choi, Wonchul; Sung, Gun Yong; Jang, Moongyu

    2015-03-01

    The electric and the thermoelectric properties of 50-nm n- and p-type silicon nanowires (SiNWs) obtained by doping with boron di-fluoride and phosphorus, respectively, were investigated by varying the doping concentration from 1.0 × 1020 to 2.5 × 1021 cm -3. The SiNWs were manufactured using conventional semiconductor processing techniques. The values of the optimized maximum power factor values were 1.59 and 2.43 mW·m -1K-2 for the n- and the p-type SiNWs at a doping concentration of 4.0 × 1020 cm-3. For doping concentrations higher than over 4.0 × 1020 cm-3, the electrical resistivity was larger and the Seebeck coefficient was sharply lower due to imperfections in the crystal structure. For lower doping concentrations below 4.0 × 1020 cm-3, the increased resistivity had a dominant impact on the power factor.

  13. Role of a-Si:H in lateral growth of crystalline silicon nanowires using Pb and In catalysts

    Czech Academy of Sciences Publication Activity Database

    Kočka, Jan; Müller, Martin; Stuchlík, Jiří; Stuchlíková, The-Ha; Červenka, Jiří; Fejfar, Antonín

    2016-01-01

    Roč. 213, č. 7 (2016), s. 1821-1825 ISSN 1862-6300 R&D Projects: GA ČR GA16-12355S Institutional support: RVO:68378271 Keywords : amorphous films * catalyst s * chemical vapor deposition * amorphous silicon Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.775, year: 2016

  14. Endotaxial silicide nanowires: A review

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, P.A., E-mail: peter.bennett@asu.edu [Physics Department, Arizona State University, Tempe, AZ 85287 (United States); School of Materials, Arizona State University, Tempe, AZ 85287 (United States); He, Zhian [School of Materials, Arizona State University, Tempe, AZ 85287 (United States); Smith, David J. [Physics Department, Arizona State University, Tempe, AZ 85287 (United States); School of Materials, Arizona State University, Tempe, AZ 85287 (United States); Ross, F.M. [IBM T. J. Watson Research Center, Yorktown Heights NY 10598 (United States)

    2011-10-03

    We review the topic of self-assembled endotaxial silicide nanowires on silicon. Crystallographic orientation, lattice mismatch and average dimensions are discussed for a variety of systems including Ti, Mn, Fe, Co, Ni, Pt and several rare earths on Si(100), Si(111) and Si(110) surfaces. In situ observations of growth dynamics support a constant-shape growth model, in which length, width and thickness all change in proportion as the nanowire grows, with thermally activated, facet-dependent rates.

  15. Ultrasmall silicon quantum dots

    NARCIS (Netherlands)

    Zwanenburg, F.A.; Van Loon, A.A.; Steele, G.A.; Rijmenam, C.E.W.M.; Balder, T.; Fang, Y.; Lieber, C.M.; Kouwenhoven, L.P.

    2009-01-01

    We report the realization of extremely small single quantum dots in p-type silicon nanowires, defined by Schottky tunnel barriers with Ni and NiSi contacts. Despite their ultrasmall size the NiSi–Si–NiSi nanowire quantum dots readily allow spectroscopy of at least ten consecutive holes, and

  16. Pulsed laser deposition of aluminum nitride nanowires

    Science.gov (United States)

    Yunusova, N. R.; Kargin, N. I.; Ryndya, S. M.; Gusev, A. S.; Antonenko, S. V.; Timofeev, A. A.

    2018-01-01

    The possibility of AlN nanowires deposition on single-crystal silicon substrates by pulsed laser deposition in vacuum is shown in this work. Experimental samples were investigated by scanning electron microscopy and infrared Fourier spectroscopy. It is shown that the possible mechanism for the AlN nanowires formation is the "vapor-liquid-crystal" mechanism.

  17. 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...

  18. Semiconductor nanowires directly grown on graphene--towards wafer scale transferable nanowire arrays with improved electrical contact.

    Science.gov (United States)

    Alper, John P; Gutes, Albert; Carraro, Carlo; Maboudian, Roya

    2013-05-21

    We present for the first time the growth of dense arrays of silicon and silicon carbide nanowires directly on graphene as well as methods of transferring these novel hybrids to arbitrary substrates. Improved electrical contact for SiC nanowire/graphene hybrid is demonstrated in the application of a robust supercapacitor electrode.

  19. Multiple Schottky Barrier-Limited Field-Effect Transistors on a Single Silicon Nanowire with an Intrinsic Doping Gradient.

    Science.gov (United States)

    Barreda, Jorge L; Keiper, Timothy D; Zhang, Mei; Xiong, Peng

    2017-04-05

    In comparison to conventional (channel-limited) field-effect transistors (FETs), Schottky barrier-limited FETs possess some unique characteristics which make them attractive candidates for some electronic and sensing applications. Consequently, modulation of the nano Schottky barrier at a metal-semiconductor interface promises higher performance for chemical and biomolecular sensor applications when compared to conventional FETs with ohmic contacts. However, the fabrication and optimization of devices with a combination of ideal ohmic and Schottky contacts as the source and drain, respectively, present many challenges. We address this issue by utilizing Si nanowires (NWs) synthesized by a chemical vapor deposition process which yields a pronounced doping gradient along the length of the NWs. Devices with a series of metal contacts on a single Si NW are fabricated in a single lithography and metallization process. The graded doping profile of the NW is manifested in monotonic increases in the channel and junction resistances and variation of the nature of the contacts from ohmic to Schottky of increasing effective barrier height along the NW. Hence multiple single Schottky junction-limited FETs with extreme asymmetry and high reproducibility are obtained on an individual NW. A definitive correlation between increasing Schottky barrier height and enhanced gate modulation is revealed. Having access to systematically varying Schottky barrier contacts on the same NW device provides an ideal platform for identifying optimal device characteristics for sensing and electronic applications.

  20. 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.

  1. 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)

  2. Imaging Spatial Variations in the Dissipation and Transport of Thermal Energy within Individual Silicon Nanowires Using Ultrafast Microscopy.

    Science.gov (United States)

    Cating, Emma E M; Pinion, Christopher W; Van Goethem, Erika M; Gabriel, Michelle M; Cahoon, James F; Papanikolas, John M

    2016-01-13

    Thermal management is an important consideration for most nanoelectronic devices, and an understanding of the thermal conductivity of individual device components is critical for the design of thermally efficient systems. However, it can be difficult to directly probe local changes in thermal conductivity within a nanoscale system. Here, we utilize the time-resolved and diffraction-limited imaging capabilities of ultrafast pump-probe microscopy to determine, in a contact-free configuration, the local thermal conductivity in individual Si nanowires (NWs). By suspending single NWs across microfabricated trenches in a quartz substrate, the properties of the same NW both on and off the substrate are directly compared. We find the substrate has no effect on the recombination lifetime or diffusion length of photogenerated charge carriers; however, it significantly impacts the thermal relaxation properties of the NW. In substrate-supported regions, thermal energy deposited into the lattice by the ultrafast laser pulse dissipates within ∼10 ns through thermal diffusion and coupling to the substrate. In suspended regions, the thermal energy persists for over 100 ns, and we directly image the time-resolved spatial motion of the thermal signal. Quantitative analysis of the transient images permits direct determination of the NW's local thermal conductivity, which we find to be a factor of ∼4 smaller than in bulk Si. Our results point to the strong potential of pump-probe microscopy to be used as an all-optical method to quantify the effects of localized environment and morphology on the thermal transport characteristics of individual nanostructured components.

  3. AlGaAs and AlGaAs/GaAs/AlGaAs nanowires grown by molecular beam epitaxy on silicon substrates

    DEFF Research Database (Denmark)

    Cirlin, G E; Reznik, R R; Shtrom, I V

    2017-01-01

    The data on growth peculiarities and physical properties of GaAs insertions embedded in AlGaAs nanowires grown on different (1 1 1) substrates by Au-assisted molecular beam epitaxy are presented. The influence of nanowires growth conditions on structural and optical properties is studied in detail...

  4. 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)].

  5. Molecular precursor derived silicon boron carbonitride/carbon nanotube and silicon oxycarbide/carbon nanotube composite nanowires for energy based applications

    Science.gov (United States)

    Bhandavat, Romil

    Molecular precursor derived ceramics (also known as polymer-derived ceramics or PDCs) are high temperature glasses that have been studied for applications involving operation at elevated temperatures. Prepared from controlled thermal degradation of liquid-phase organosilicon precursors, these ceramics offer remarkable engineering properties such as resistance to crystallization up to 1400 °C, semiconductor behavior at high temperatures and intense photoluminescence. These properties are a direct result of their covalent bonded amorphous network and free (-sp2) carbon along with mixed Si/B/C/N/O bonds, which otherwise can not be obtained through conventional ceramic processing techniques. This thesis demonstrates synthesis of a unique core/shell type nanowire structure involving either siliconboroncarbonitride (SiBCN) or siliconoxycarbide (SiOC) as the shell with carbon nanotube (CNT) acting as the core. This was made possible by liquid phase functionalization of CNT surfaces with respective polymeric precursor (e.g., home-made boron-modified polyureamethylvinylsilazane for SiBCN/CNT and commercially obtained polysiloxane for SiOC/CNT), followed by controlled pyrolysis in inert conditions. This unique architecture has several benefits such as high temperature oxidation resistance (provided by the ceramic shell), improved electrical conductivity and mechanical toughness (attributed to the CNT core) that allowed us to explore its use in energy conversion and storage devices. The first application involved use of SiBCN/CNT composite as a high temperature radiation absorbant material for laser thermal calorimeter. SiBCN/CNT spray coatings on copper substrate were exposed to high energy laser beams (continuous wave at 10.6 mum 2.5 kW CO2 laser, 10 seconds) and resulting change in its microstructure was studied ex-situ. With the aid of multiple techniques we ascertained the thermal damage resistance to be 15 kW/cm -2 with optical absorbance exceeding 97%. This represents

  6. 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.

  7. Imaging Localized Energy States in Silicon-doped InGaN Nanowires Using 4D Electron Microscopy

    KAUST Repository

    Bose, Riya

    2018-01-23

    Introducing dopants into InGaN NWs is known to significantly improve their device performances through a variety of mechanisms. However, to further optimize device operation under the influence of large specific surfaces, a thorough knowledge of ultrafast dynamical processes at the surface and interface of these NWs is imperative. Here, we describe the development of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) as an extremely surface-sensitive method to directly visualize in space and time the enormous impact of silicon doping on the surface-carrier dynamics of InGaN NWs. Two time regime dynamics are identified for the first time in a 4D S-UEM experiment: an early time behavior (within 200 picoseconds) associated with the deferred evolution of secondary electrons due to the presence of localized trap states that decrease the electron escape rate and a longer timescale behavior (several ns) marked by accelerated charge carrier recombination. The results are further corroborated by conductivity studies carried out in dark and under illumination.

  8. Electrochemical biosensors

    CERN Document Server

    Cosnier, Serge

    2015-01-01

    "This is an excellent book on modern electrochemical biosensors, edited by Professor Cosnier and written by leading international experts. It covers state-of-the-art topics of this important field in a clear and timely manner."-Prof. Joseph Wang, UC San Diego, USA  "This book covers, in 13 well-illustrated chapters, the potential of electrochemical methods intimately combined with a biological component for the assay of various analytes of biological and environmental interest. Particular attention is devoted to the description of electrochemical microtools in close contact with a biological cell for exocytosis monitoring and to the use of nanomaterials in the electrochemical biosensor architecture for signal improvement. Interestingly, one chapter describes the concept and design of self-powered biosensors derived from biofuel cells. Each topic is reviewed by experts very active in the field. This timely book is well suited for providing a good overview of current research trends devoted to electrochemical...

  9. Electron Transport in Si Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ramayya, E [Arizona State University, Tempe, AZ (United States); Vasileska, D [Arizona State University, Tempe, AZ (United States); Goodnick, S M [Arizona State University, Tempe, AZ (United States); Knezevic, I [University of Wisconsin, Madison, WI (United States)

    2006-05-15

    We investigate electron transport in silicon nanowires taking into account acoustic, non-polar optical phonons and surface/interface roughness scattering. We find that at very high transverse fields the reduced density of final states to which the carriers can scatter into gives rise to a reduced influence of interface-roughness scattering, which is promising result from a fabrication point of view.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Semiconductor nanowires and templates for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Ying, Xiang

    2009-07-15

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

  12. Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, Frank; Schiek, Manuela; Al-Shamery, Katharina

    Single crystalline nanowires from fluorescing organic molecules like para-phenylenes or thiophenes are supposed to become key elements in future integrated optoelectronic devices [1]. For a sophisticated design of devices based on nanowires the basic principles of the nanowire formation have...... to be well understood [2]. Nanowires from para-phenylenes, from ®-thiophenes, and from phenylene/thiophene co-oligomers, Fig. 1, are investigated exemplarily. Epitaxy and electrostatic interactions determine the microscopic growth mechanism, whereas kinetics ascertains the macroscopic habit. Results from...

  13. Confinement-guided shaping of semiconductor nanowires and nanoribbons: "writing with nanowires".

    Science.gov (United States)

    Pevzner, Alexander; Engel, Yoni; Elnathan, Roey; Tsukernik, Alexander; Barkay, Zahava; Patolsky, Fernando

    2012-01-11

    To fully exploit their full potential, new semiconductor nanowire building blocks with ab initio controlled shapes are desired. However, and despite the great synthetic advances achieved, the ability to control nanowire's geometry has been significantly limited. Here, we demonstrate a simple confinement-guided nanowire growth method that enables to predesign not only the chemical and physical attributes of the synthesized nanowires but also allows a perfect and unlimited control over their geometry. Our method allows the synthesis of semiconductor nanowires in a wide variety of two-dimensional shapes such as any kinked (different turning angles), sinusoidal, linear, and spiral shapes, so that practically any desired geometry can be defined. The shape-controlled nanowires can be grown on almost any substrate such as silicon wafer, quartz and glass slides, and even on plastic substrates (e.g., Kapton HN). © 2011 American Chemical Society

  14. Surface Patterning and Nanowire Biosensor Construction

    DEFF Research Database (Denmark)

    Iversen, Lars

    2008-01-01

    assembly on e.g. glass surfaces, providing parallel patterning via gentle and oriented protein immobilization. Such protein patterns are useful for miniaturized bioassays of protein function. Second, in a very different approach, we use a highly focused laser beam to locally desorb alkanethiols from a self...... assembled monolayer on gold, a technique useful for creating diverse monolayer patterns in a direct-write fashion. Addition of a second alkanethiol forms a topologically ultra flat but chemically patterned surface, which by inspection with scanning electron microscopy and atomic force microscopy revealed...

  15. Nanofabrication of structures for the study of nanowire doping

    Science.gov (United States)

    Eichfeld, Chad

    A variety of techniques were developed for the characterization of nanowires and applied to the study of nanowire growth and dopant incorporation. A technique to selectively plate gold on the n-type regions of modulation-doped silicon nanowires for junction delineation was developed. The ability to electrolessly deposit metal on segments of nanowires could also facilitate electrical contact formation. More complicated structures such as controlled placement of forks along the nanowire could be made by placement of the gold catalyst at predetermined locations along a nanowire followed by a second growth. Additionally, a process was developed that focuses on using this plating ability to grow silicon nanowires horizontally from pre-determined locations. The processing was worked out and nanowires were grown horizontally from plated gold, but the selectivity of gold limited the ability to grow wires in only the desired locations. A silicon nanowire local electrode atom probe test structure is discussed from the initial design steps to successfully using the test structure to analyze silicon nanowires. Initial results using laser pulsed assisted local electrode atom probe indicated that the thermal properties of the nanowire prevent the tip from cooling fast enough and resulted in large thermal tails in the mass spectra. Thermal modeling was used to identify what nanowire diameters and metal coatings would allow the nanowire tip to cool sufficiently fast. A silver catalyzed silicon nanowire with a diameter large enough to allow for sufficient cooling was analyzed, and the concentration of silver in the silicon nanowire was below the detection limit of 10 ppm or 5 x 10 17 cm-3. The growth and characterization of Al catalyzed silicon nanowires is also discussed. Nanowires were grown at higher pressures and using H 2 as a carrier gas resulting in much higher growth rates than previously observed for Al catalyzed nanowires in the literature. The nanowires were

  16. Boron carbide nanowires with uniform CNx coatings

    Science.gov (United States)

    Zhang, H. Z.; Wang, R. M.; You, L. P.; Yu, J.; Chen, H.; Yu, D. P.; Chen, Y.

    2007-01-01

    Boron carbide nanowires with uniform carbon nitride coating layers were synthesized on a silicon substrate using a simple thermal process. The structure and morphology of the as-synthesized nanowires were characterized using x-ray diffraction, scanning and transmission electron microscopy and electron energy loss spectroscopy. A correlation between the surface smoothness of the nanowire sidewalls and their lateral sizes has been observed and it is a consequence of the anisotropic formation of the coating layers. A growth mechanism is also proposed for these growth phenomena.

  17. Structural and optical properties of self-catalytic GaAs:Mn nanowires grown by molecular beam epitaxy on silicon substrates

    DEFF Research Database (Denmark)

    Gas, Katarzyna; Sadowski, Janusz; Kasama, Takeshi

    2013-01-01

    Mn-doped GaAs nanowires were grown in the self-catalytic growth mode on the oxidized Si(100) surface by molecular beam epitaxy and characterized by scanning and transmission electron microscopy, Raman scattering, photoluminescence, cathodoluminescence, and electron transport measurements. The tra...

  18. Fabrication and Gas-Sensing Properties of Ni-Silicide/Si Nanowires

    OpenAIRE

    Hsu, Hsun-Feng; Chen, Chun-An; Liu, Shang-Wu; Tang, Chun-Kai

    2017-01-01

    Ni-silicide/Si nanowires were fabricated by atomic force microscope nano-oxidation on silicon-on-insulator substrates, selective wet etching, and reactive deposition epitaxy. Ni-silicide nanocrystal-modified Si nanowire and Ni-silicide/Si heterostructure multi-stacked nanowire were formed by low- and high-coverage depositions of Ni, respectively. The Ni-silicide/Si Schottky junction and Ni-silicide region were attributed high- and low-resistance parts of nanowire, respectively, causing the re...

  19. 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

    can be done by reducing the dimensions of the electrodes to nanoscale dimensions. Here we report a fabrication method of a nanoscale four-point probe utilizing silicon nanowires as templates for metal electrodes. Using nanomanipulation, we attach 200–300 nm wide silicon nanowires to microfabricated...

  20. Silicon plasmonics at midinfrared using silicon-insulator-silicon platform

    Science.gov (United States)

    Gamal, Rania; Shafaay, Sarah; Ismail, Yehea; Swillam, Mohamed A.

    2017-01-01

    We propose devices based on doped silicon. Doped silicon is designed to act as a plasmonic medium in the midinfrared (MIR) range. The surface plasmon frequency of the doped silicon can be tuned within the MIR range, which gives rise to useful properties in the material's dispersion. We propose various plasmonic configurations that can be utilized for silicon on-chip applications in MIR. These devices have superior performance over conventional silicon devices and provide unique functionalities such as 90-sharp degree bends, T- and X-junction splitters, and stubs. These devices are CMOS-compatible and can be easily integrated with other electronic devices. In addition, the potential for biological and environmental sensing using doped silicon nanowires is demonstrated.

  1. Nanowire Optoelectronics

    OpenAIRE

    Wang Zhihuan; Nabet Bahram

    2015-01-01

    Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, light-emitting diodes (LEDs), lasers, sensors, and optical antennas. We review the optical properties of these nanowires in terms of absorption, guiding, and radiation of light, which may be termed light management. Analysis of the interaction of light with long cylindrical/hexagonal structures with ...

  2. Nanowire Lasers

    Directory of Open Access Journals (Sweden)

    Couteau C.

    2015-05-01

    Full Text Available We review principles and trends in the use of semiconductor nanowires as gain media for stimulated emission and lasing. Semiconductor nanowires have recently been widely studied for use in integrated optoelectronic devices, such as light-emitting diodes (LEDs, solar cells, and transistors. Intensive research has also been conducted in the use of nanowires for subwavelength laser systems that take advantage of their quasione- dimensional (1D nature, flexibility in material choice and combination, and intrinsic optoelectronic properties. First, we provide an overview on using quasi-1D nanowire systems to realize subwavelength lasers with efficient, directional, and low-threshold emission. We then describe the state of the art for nanowire lasers in terms of materials, geometry, andwavelength tunability.Next,we present the basics of lasing in semiconductor nanowires, define the key parameters for stimulated emission, and introduce the properties of nanowires. We then review advanced nanowire laser designs from the literature. Finally, we present interesting perspectives for low-threshold nanoscale light sources and optical interconnects. We intend to illustrate the potential of nanolasers inmany applications, such as nanophotonic devices that integrate electronics and photonics for next-generation optoelectronic devices. For instance, these building blocks for nanoscale photonics can be used for data storage and biomedical applications when coupled to on-chip characterization tools. These nanoscale monochromatic laser light sources promise breakthroughs in nanophotonics, as they can operate at room temperature, can potentially be electrically driven, and can yield a better understanding of intrinsic nanomaterial properties and surface-state effects in lowdimensional semiconductor systems.

  3. 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.

  4. 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.

  5. 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......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...

  6. Ultralow-power non-volatile memory cells based on P(VDF-TrFE) ferroelectric-gate CMOS silicon nanowire channel field-effect transistors.

    Science.gov (United States)

    Van, Ngoc Huynh; Lee, Jae-Hyun; Whang, Dongmok; Kang, Dae Joon

    2015-07-21

    Nanowire-based ferroelectric-complementary metal-oxide-semiconductor (NW FeCMOS) nonvolatile memory devices were successfully fabricated by utilizing single n- and p-type Si nanowire ferroelectric-gate field effect transistors (NW FeFETs) as individual memory cells. In addition to having the advantages of single channel n- and p-type Si NW FeFET memory, Si NW FeCMOS memory devices exhibit a direct readout voltage and ultralow power consumption. The reading state power consumption of this device is less than 0.1 pW, which is more than 10(5) times lower than the ON-state power consumption of single-channel ferroelectric memory. This result implies that Si NW FeCMOS memory devices are well suited for use in non-volatile memory chips in modern portable electronic devices, especially where low power consumption is critical for energy conservation and long-term use.

  7. Self-assembled silicon oxide nanojunctions

    International Nuclear Information System (INIS)

    Lin, L W; Tang, Y H; Chen, C S

    2009-01-01

    Novel silicon oxide nanojunction structures with various shapes, such as X type, Y type, T type, ringlike and treelike, are fabricated in a self-assembled manner by the hydrothermal method without any metallic catalyst. In the silicon oxide nanojunctions, both the silicon oxide nanowire part and the junction part consist of the same chemical composition, forming homogeneous homojunctions and being made suitable for application in nanoscale optoelectronics devices. The formation of silicon oxide nanojunctions may be influenced by the surrounding environment in the reaction kettle, growth space among the silicon oxide nanowires and the weight of SiO droplets at the growth tip.

  8. 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.

  9. From Nanostructure to Nano Biosensor: Institute of Nano Electronic Engineering (INEE, UniMAP Experience

    Directory of Open Access Journals (Sweden)

    U Hashim

    2012-02-01

    Full Text Available Nanostructure is defined as something that has a physical dimension smaller than 100 nanometers, ranging from clusters and/or to dimensional layers of atoms. There are three most important nanostructures that are extensively studied and researched in various organizations including Institute of Nano Electronic Engineering (INEE in UniMAP. These include quantum dot, nanowire, and nanogap, which have been successfully designed and fabricated using in-house facilities available. These are subsequently used as a main sensing component in nanostructures based biosensor. This fabrication, characterization and testing job were done within four main interlinked laboratories namely microfabrication cleanroom, nanofabrication cleanroom, failure analysis laboratory and nano biochip laboratory.  Currently, development of Nano Biosensor is the main research focus in INEE. In principle, biosensor is an analytical device which converts a biological response into an electrical signal.   Keywords: Nanostructure, INEE , nanowire , nanogap and Nano Biosensor

  10. Disposable amperometric biosensor based on nanostructured bacteriophages for glucose detection

    International Nuclear Information System (INIS)

    Kang, Yu Ri; Kim, Ju Hwan; Kim, Soo Won; Hwang, Kyung Hoon; Nam, Chang Hoon

    2010-01-01

    The selection of electrode material profoundly influences biosensor science and engineering, as it heavily influences biosensor sensitivity. Here we propose a novel electrochemical detection method using a working electrode consisting of bio-nanowires from genetically modified filamentous phages and nanoparticles. fd-tet p8MMM filamentous phages displaying a three-methionine (MMM) peptide on the major coat protein pVIII (designated p8MMM phages) were immobilized on the active area of an electrochemical sensor through physical adsorption and chemical bonding. Bio-nanowires composed of p8MMM phages and silver nanoparticles facilitated sensitive, rapid and selective detection of particular molecules. We explored whether the composite electrode with bio-nanowires was an effective platform to detect the glucose oxidase. The current response of the bio-nanowire sensor was high at various glucose concentrations (0.1 µm–0.1 mM). This method provides a considerable advantage to demonstrate analyte detection over low concentration ranges. Especially, phage-enabled bio-nanowires can serve as receptors with high affinity and specificity for the detection of particular biomolecules and provide a convenient platform for designing site-directed multifunctional scaffolds based on bacteriophages and may serve as a simple method for label-free detection

  11. 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.

  12. 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....

  13. Epitaxial Integration of Nanowires in Microsystems by Local Micrometer Scale Vapor Phase Epitaxy

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Wacaser, Brent A.; Petersen, Dirch Hjorth

    2008-01-01

    a small microfabricated heater, growth of nanowires can be achieved locally without heating the entire microsystem, thereby reducing the compatibility problems. The first demonstration of epitaxial growth of silicon nanowires by this method is presented and shows that the microsystem can be used for rapid...... optimization of VPE conditions. The important issue of the cross-contamination of other parts of the microsystem caused by the local growth of nanowires is also investigated by growth of GaN near previously grown silicon nanowires. The design of the cantilever heaters makes it possible to study the grown...

  14. High-efficiency optical terahertz modulation of aligned Ag nanowires on a Si substrate

    Science.gov (United States)

    Lee, Gyuseok; Maeng, Inhee; Kang, Chul; Oh, Myoung-Kyu; Kee, Chul-Sik

    2018-03-01

    High-efficiency optical modulation of a terahertz pulse transmitted through aligned silver nanowires on a silicon substrate is demonstrated. Without optical excitation, the terahertz pulses mostly pass through the silver nanowires. However, an optically excited sample significantly modulates the transmittance compared with an excited silicon substrate. The enhanced modulation efficiency is explained by the redistribution effect of photo-carriers due to the nanowires. The simple structure of metal nanowires on a semiconductor substrate could be useful in implementing optically tunable terahertz wave modulators.

  15. Plasmonic Nanostructures for Biosensor Applications

    Science.gov (United States)

    Gadde, Akshitha

    Improving the sensitivity of existing biosensors is an active research topic that cuts across several disciplines, including engineering and biology. Optical biosensors are the one of the most diverse class of biosensors which can be broadly categorized into two types based on the detection scheme: label-based and label-free detection. In label-based detection, the target bio-molecules are labeled with dyes or tags that fluoresce upon excitation, indicating the presence of target molecules. Label-based detection is highly-sensitive, capable of single molecule detection depending on the detector type used. One method of improving the sensitivity of label-based fluorescence detection is by enhancement of the emission of the labels by coupling them with metal nanostructures. This approach is referred as plasmon-enhanced fluorescence (PEF). PEF is achieved by increasing the electric field around the nano metal structures through plasmonics. This increased electric field improves the enhancement from the fluorophores which in turn improves the photon emission from the fluorophores which, in turn, improves the limit of detection. Biosensors taking advantage of the plasmonic properties of metal films and nanostructures have emerged an alternative, low-cost, high sensitivity method for detecting labeled DNA. Localized surface plasmon resonance (LSPR) sensors employing noble metal nanostructures have recently attracted considerable attention as a new class of plasmonic nanosensors. In this work, the design, fabrication and characterization of plasmonic nanostructures is carried out. Finite difference time domain (FDTD) simulations were performed using software from Lumerical Inc. to design a novel LSPR structure that exhibit resonance overlapping with the absorption and emission wavelengths of quantum dots (QD). Simulations of a composite Au/SiO2 nanopillars on silicon substrate were performed using FDTD software to show peak plasmonic enhancement at QD emission wavelength

  16. Biosensors of bacterial cells.

    Science.gov (United States)

    Burlage, Robert S; Tillmann, Joshua

    2017-07-01

    Biosensors are devices which utilize both an electrical component (transducer) and a biological component to study an environment. They are typically used to examine biological structures, organisms and processes. The field of biosensors has now become so large and varied that the technology can often seem impenetrable. Yet the principles which underlie the technology are uncomplicated, even if the details of the mechanisms are elusive. In this review we confine our analysis to relatively current advancements in biosensors for the detection of whole bacterial cells. This includes biosensors which rely on an added labeled component and biosensors which do not have a labeled component and instead detect the binding event or bound structure on the transducer. Methods to concentrate the bacteria prior to biosensor analysis are also described. The variety of biosensor types and their actual and potential uses are described. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Linear self-assembly and grafting of gold nanorods into arrayed micrometer-long nanowires on a silicon wafer via a combined top-down/bottom-up approach.

    Science.gov (United States)

    Lestini, Elena; Andrei, Codrin; Zerulla, Dominic

    2018-01-01

    Macroscopically long wire-like arrangements of gold nanoparticles were obtained by controlled evaporation and partial coalescence of an aqueous colloidal solution of capped CTAB-Au nanorods onto a functionalised 3-mercaptopropyl trimethoxysilane (MPTMS) silicon substrate, using a removable, silicon wafer with a hydrophobic surface that serves as a "handrail" for the initial nanorods' linear self-assembly. The wire-like structures display a quasi-continuous pattern by thermal annealing of the gold nanorods when the solvent (i.e. water) is evaporated at temperatures rising from 20°C to 140°C. Formation of both single and self-replicating parallel 1D-superstructures consisting of two or even three wires is observed and explained under such conditions.

  18. Water Splitting over Epitaxially Grown InGaN Nanowires on-Metallic Titanium/Silicon Template: Reduced Interfacial Transfer Resistance and Improved Stability

    KAUST Repository

    Ebaid, Mohamed

    2018-03-09

    Water splitting using InGaN-based photocatalysts may have a great contribution in future renewable energy production systems. Among the most important parameters to solve are those related to substrate lattice-matching compatibility. Here, we directly grow InGaN nanowires (NWs) on a metallic Ti/Si template, for improving water splitting performance compared to a bare Si substrate. The open circuit potential of the epitaxially grown InGaN NWs on metallic Ti was almost two times that of those grown on Si substrate. The interfacial transfer resistance was also reduced significantly after introducing the metallic Ti interlayer. An applied-bias-photon-to-current conversion efficiency of 2.2% and almost unity Faradic efficiency for hydrogen generation were achieved using this approach. The InGaN NWs grown on Ti showed improved stability of hydrogen generation under continuous operation conditions, when compared to those grown on Si, emphasizing the role of the semiconductor-on-metal approach in enhancing the overall efficiency of water splitting catalysts.

  19. Understanding the influence of electrolyte additives on the electrochemical performance and morphology evolution of silicon nanowire based lithium-ion battery anodes

    Science.gov (United States)

    Kennedy, Tadhg; Brandon, Michael; Laffir, Fathima; Ryan, Kevin M.

    2017-08-01

    Here we report new insights into the effect various electrolyte additives have on the cycling stability and rate capability of Si nanowire (NW) Li-ion battery anodes. The additives tested were vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate and lithium bis(oxalato)borate. All four significantly improve the capacity retention of the electrodes over 250 cycles compared to the additive-free electrolyte, with vinylene carbonate being the outstanding performer. The results provide a new understanding of the cycling behaviour of Si in the presence of electrolyte additives, revealing that not only is the stability of the SEI layer affected but that this consequently has a profound influence on the morphology evolution and chemical composition of the Si active material. Ex-situ characterisation of the electrodes post-cycling demonstrates that the improvement in cycling stability arises as the additives minimise irreversible decomposition reactions at the surface and facilitate a transformation from a NW morphology into a porous sponge-like network. This transformation process does not occur in the absence of any stable SEI forming additives as instability in the passivating layer leads to the continuous and irreversible consumption of Si to form Li silicates.

  20. Biosensors and bioelectronics

    CERN Document Server

    Karunakaran, Chandran; Benjamin, Robson

    2015-01-01

    Biosensors and Bioelectronics presents the rapidly evolving methodologies that are relevant to biosensors and bioelectronics fabrication and characterization. The book provides a comprehensive understanding of biosensor functionality, and is an interdisciplinary reference that includes a range of interwoven contributing subjects, including electrochemistry, nanoparticles, and conducting polymers. Authored by a team of bioinstrumentation experts, this book serves as a blueprint for performing advanced fabrication and characterization of sensor systems-arming readers with an application-based re

  1. Robust ultrasensitive tunneling-FET biosensor for point-of-care diagnostics

    Science.gov (United States)

    Gao, Anran; Lu, Na; Wang, Yuelin; Li, Tie

    2016-01-01

    For point-of-care (POC) applications, robust, ultrasensitive, small, rapid, low-power, and low-cost sensors are highly desirable. Here, we present a novel biosensor based on a complementary metal oxide semiconductor (CMOS)-compatible silicon nanowire tunneling field-effect transistor (SiNW-TFET). They were fabricated “top-down” with a low-cost anisotropic self-stop etching technique. Notably, the SiNW-TFET device provided strong anti-interference capacity by applying the inherent ambipolarity via both pH and CYFRA21-1 sensing. This offered a more robust and portable general protocol. The specific label-free detection of CYFRA21-1 down to 0.5 fgml−1 or ~12.5 aM was achieved using a highly responsive SiNW-TFET device with a minimum sub-threshold slope (SS) of 37 mVdec−1. Furthermore, real-time measurements highlighted the ability to use clinically relevant samples such as serum. The developed high performance diagnostic system is expected to provide a generic platform for numerous POC applications. PMID:26932158

  2. Robust ultrasensitive tunneling-FET biosensor for point-of-care diagnostics

    Science.gov (United States)

    Gao, Anran; Lu, Na; Wang, Yuelin; Li, Tie

    2016-03-01

    For point-of-care (POC) applications, robust, ultrasensitive, small, rapid, low-power, and low-cost sensors are highly desirable. Here, we present a novel biosensor based on a complementary metal oxide semiconductor (CMOS)-compatible silicon nanowire tunneling field-effect transistor (SiNW-TFET). They were fabricated “top-down” with a low-cost anisotropic self-stop etching technique. Notably, the SiNW-TFET device provided strong anti-interference capacity by applying the inherent ambipolarity via both pH and CYFRA21-1 sensing. This offered a more robust and portable general protocol. The specific label-free detection of CYFRA21-1 down to 0.5 fgml-1 or ~12.5 aM was achieved using a highly responsive SiNW-TFET device with a minimum sub-threshold slope (SS) of 37 mVdec-1. Furthermore, real-time measurements highlighted the ability to use clinically relevant samples such as serum. The developed high performance diagnostic system is expected to provide a generic platform for numerous POC applications.

  3. 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.

  4. Conductive polymer nanowire gas sensor fabricated by nanoscale soft lithography

    Science.gov (United States)

    Tang, Ning; Jiang, Yang; Qu, Hemi; Duan, Xuexin

    2017-12-01

    Resistive devices composed of one-dimensional nanostructures are promising candidates for the next generation of gas sensors. However, the large-scale fabrication of nanowires is still challenging, which restricts the commercialization of such devices. Here, we report a highly efficient and facile approach to fabricating poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) nanowire chemiresistive gas sensors by nanoscale soft lithography. Well-defined sub-100 nm nanowires are fabricated on silicon substrate, which facilitates device integration. The nanowire chemiresistive gas sensor is demonstrated for NH3 and NO2 detection at room temperature and shows a limit of detection at ppb level, which is compatible with nanoscale PEDOT:PSS gas sensors fabricated with the conventional lithography technique. In comparison with PEDOT:PSS thin-film gas sensors, the nanowire gas sensor exhibits higher sensitivity and a much faster response to gas molecules.

  5. Electroluminescence from single nanowires by tunnel injection: an experimental study

    OpenAIRE

    Zimmler, Mariano A.; Bao, Jiming; Shalish, Ilan; Yi, Wei; Yoon, Joonah; Narayanamurti, Venkatesh; Capasso, Federico

    2007-01-01

    We present a hybrid light-emitting diode structure composed of an n-type gallium nitride nanowire on a p-type silicon substrate in which current is injected along the length of the nanowire. The device emits ultraviolet light under both bias polarities. Tunnel-injection of holes from the p-type substrate (under forward bias) and from the metal (under reverse bias) through thin native oxide barriers consistently explains the observed electroluminescence behaviour. This work shows that the stan...

  6. A two-colour heterojunction unipolar nanowire light-emitting diode by tunnel injection

    OpenAIRE

    Zimmler, Mariano A.; Bao, Jiming; Shalish, Ilan; Yi, Wei; Narayanamurti, Venkatesh; Capasso, Federico

    2007-01-01

    We present a systematic study of the current-voltage characteristics and electroluminescence of gallium nitride (GaN) nanowire on silicon (Si) substrate heterostructures where both semiconductors are n-type. A novel feature of this device is that by reversing the polarity of the applied voltage the luminescence can be selectively obtained from either the nanowire or the substrate. For one polarity of the applied voltage, ultraviolet (and visible) light is generated in the GaN nanowire, while ...

  7. Nanowire Optoelectronics

    Directory of Open Access Journals (Sweden)

    Wang Zhihuan

    2015-12-01

    Full Text Available Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, light-emitting diodes (LEDs, lasers, sensors, and optical antennas. We review the optical properties of these nanowires in terms of absorption, guiding, and radiation of light, which may be termed light management. Analysis of the interaction of light with long cylindrical/hexagonal structures with subwavelength diameters identifies radial resonant modes, such as Leaky Mode Resonances, or Whispering Gallery modes. The two-dimensional treatment should incorporate axial variations in “volumetric modes,”which have so far been presented in terms of Fabry–Perot (FP, and helical resonance modes. We report on finite-difference timedomain (FDTD simulations with the aim of identifying the dependence of these modes on geometry (length, width, tapering, shape (cylindrical, hexagonal, core–shell versus core-only, and dielectric cores with semiconductor shells. This demonstrates how nanowires (NWs form excellent optical cavities without the need for top and bottommirrors. However, optically equivalent structures such as hexagonal and cylindrical wires can have very different optoelectronic properties meaning that light management alone does not sufficiently describe the observed enhancement in upward (absorption and downward transitions (emission of light inNWs; rather, the electronic transition rates should be considered. We discuss this “rate management” scheme showing its strong dimensional dependence, making a case for photonic integrated circuits (PICs that can take advantage of the confluence of the desirable optical and electronic properties of these nanostructures.

  8. Vertically Integrated Multiple Nanowire Field Effect Transistor.

    Science.gov (United States)

    Lee, Byung-Hyun; Kang, Min-Ho; Ahn, Dae-Chul; Park, Jun-Young; Bang, Tewook; Jeon, Seung-Bae; Hur, Jae; Lee, Dongil; Choi, Yang-Kyu

    2015-12-09

    A vertically integrated multiple channel-based field-effect transistor (FET) with the highest number of nanowires reported ever is demonstrated on a bulk silicon substrate without use of wet etching. The driving current is increased by 5-fold due to the inherent vertically stacked five-level nanowires, thus showing good feasibility of three-dimensional integration-based high performance transistor. The developed fabrication process, which is simple and reproducible, is used to create multiple stiction-free and uniformly sized nanowires with the aid of the one-route all-dry etching process (ORADEP). Furthermore, the proposed FET is revamped to create nonvolatile memory with the adoption of a charge trapping layer for enhanced practicality. Thus, this research suggests an ultimate design for the end-of-the-roadmap devices to overcome the limits of scaling.

  9. Biosensors for Cell Analysis.

    Science.gov (United States)

    Zhou, Qing; Son, Kyungjin; Liu, Ying; Revzin, Alexander

    2015-01-01

    Biosensors first appeared several decades ago to address the need for monitoring physiological parameters such as oxygen or glucose in biological fluids such as blood. More recently, a new wave of biosensors has emerged in order to provide more nuanced and granular information about the composition and function of living cells. Such biosensors exist at the confluence of technology and medicine and often strive to connect cell phenotype or function to physiological or pathophysiological processes. Our review aims to describe some of the key technological aspects of biosensors being developed for cell analysis. The technological aspects covered in our review include biorecognition elements used for biosensor construction, methods for integrating cells with biosensors, approaches to single-cell analysis, and the use of nanostructured biosensors for cell analysis. Our hope is that the spectrum of possibilities for cell analysis described in this review may pique the interest of biomedical scientists and engineers and may spur new collaborations in the area of using biosensors for cell analysis.

  10. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

    Piraux, L.; Encinas, A.; Vila, L.

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  11. Stability of Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, F.; Schiek, M.; Wallmann, I.

    2011-01-01

    atomic force microscopy (AFM). Aging experiments under ambient conditions already show substantial morphological changes. Nanoscopic organic clusters, which initially coexist with the nanowires, vanish within hours. Thermal annealing of nanowire samples leads to even more pronounced morphology changes...

  12. 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.

  13. Nanotubes and nanowires

    Indian Academy of Sciences (India)

    Unknown

    nanotubes are likely to be useful as nanochips since they exhibit diode properties at the junction. By making use of carbon nanotubes, nanowires of metals, metal oxides and GaN have been obtained. Both the oxide and GaN nanowires are single crystalline. Gold nanowires exhibit plasmon bands varying markedly with.

  14. Fabrication and characterization of silicon nanowires by means of molecular beam epitaxy; Herstellung und Charakterisierung von Silizium-Nanodraehten mittels Molekularstrahlepitaxie

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Luise

    2007-06-19

    In this work, basic processes of silicon whisker growth were examined. For the first time, Si nanowhiskers were produced under UHV conditions by Molecular Beam Epitaxy (MBE) and characterized by different analysis methods afterwards. The existence of Au/Si droplets on a Si(111) substrate surface is a precondition of this growth method. Analyses of the temporal development of the Au/Si droplets during the whisker growth show a decrease of the number of small droplets resp. whiskers during the whisker growth with increasing growth time. This behaviour, i.e. the dissolution of smaller droplets/whiskers and the growth of larger ones in parallel can be explained by Ostwald ripenning. The diffusion-determined material transition of gold, which occurs during this process, is theoretically described by the Lifshitz-Slyozov-Wagner (LSW)-Theory. After this theory only whiskers grow which radii are larger than the critical radius. The whisker radii are temperature dependend whereas analogous whisker radii exist for identical growth times. Electron microscopy analysis show that all whiskers possess a hexagonal but no cylindrical habitus. The planes that form during the growth are crystallographic (111) planes. The growth of Si nanowhiskers under MBE conditions is determined by the Vapour Liquid Solid (VLS) mechanism and by surface diffusion of Si atoms. (orig.)

  15. Growth of colloidal gold nanostars and nanowires induced by palladium doping.

    Science.gov (United States)

    Krichevski, Olga; Markovich, Gil

    2007-01-30

    Gold-palladium nanocrystals with starlike shapes and high aspect ratio nanowires were grown in a surfactant solution. The incorporation of palladium into the growing gold nanostructures induced nanowire formation with high yield. Kinetic control of the metal deposition rate through tuning of the pH value to about 5 was crucial for the nanowire growth. The nanostructures were characterized by high-resolution electron microscopy and energy-dispersive X-ray spectroscopy. The Au-Pd nanowires were deposited on functionalized silicon wafers.

  16. Introduction to biosensors

    Science.gov (United States)

    Bhalla, Nikhil; Jolly, Pawan; Formisano, Nello

    2016-01-01

    Biosensors are nowadays ubiquitous in biomedical diagnosis as well as a wide range of other areas such as point-of-care monitoring of treatment and disease progression, environmental monitoring, food control, drug discovery, forensics and biomedical research. A wide range of techniques can be used for the development of biosensors. Their coupling with high-affinity biomolecules allows the sensitive and selective detection of a range of analytes. We give a general introduction to biosensors and biosensing technologies, including a brief historical overview, introducing key developments in the field and illustrating the breadth of biomolecular sensing strategies and the expansion of nanotechnological approaches that are now available. PMID:27365030

  17. 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)

  18. Special Issue: The Silicon Age

    Science.gov (United States)

    Kittler, Martin; Yang, Deren

    2006-03-01

    The present issue of physica status solidi (a) contains a collection of articles about different aspects of current silicon research and applications, ranging from basic investigations of mono- and polycrystalline silicon materials and nanostructures to technologies for device fabrication in silicon photovoltaics, micro- and optoelectronics. Guest Editors are Martin Kittler and Deren Yang, the organizers of a recent Sino-German symposium held in Cottbus, Germany, 19-24 September 2005.The cover picture shows four examples of The Silicon Age: the structure of a thin film solar cell on low-cost SSP (silicon sheet from powder) substrate (upper left image) [1], a high-resolution transmission electron microscopy image and diffraction pattern of a single-crystalline Si nanowire (upper right) [2], a carrier lifetime map from an n-type multicrystalline silicon wafer after gettering by a grain boundary (lower left) [3], and a scanning acoustic microscopy image of a bonded 150 mm diameter wafer pair (upper right) [4].

  19. Biosensors Incorporating Bimetallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    John Rick

    2015-12-01

    Full Text Available This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs, which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today’s society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given.

  20. BIOSENSORS FOR ENVIRONMENTAL APPLICATIONS

    Science.gov (United States)

    A review, with 19 references, is given on challenges and possible opportunities for the development of biosensors for environmental monitoring applications. The high cost and slow turnaround times typically associated with the measurement of regulated pollutants clearly indicates...