Fabrication and characterization of active nanostructures

Science.gov (United States)

Opondo, Noah F.

Three different nanostructure active devices have been designed, fabricated and characterized. Junctionless transistors based on highly-doped silicon nanowires fabricated using a bottom-up fabrication approach are first discussed. The fabrication avoids the ion implantation step since silicon nanowires are doped in-situ during growth. Germanium junctionless transistors fabricated with a top down approach starting from a germanium on insulator substrate and using a gate stack of high-k dielectrics and GeO2 are also presented. The levels and origin of low-frequency noise in junctionless transistor devices fabricated from silicon nanowires and also from GeOI devices are reported. Low-frequency noise is an indicator of the quality of the material, hence its characterization can reveal the quality and perhaps reliability of fabricated transistors. A novel method based on low-frequency noise measurement to envisage trap density in the semiconductor bandgap near the semiconductor/oxide interface of nanoscale silicon junctionless transistors (JLTs) is presented. Low-frequency noise characterization of JLTs biased in saturation is conducted at different gate biases. The noise spectrum indicates either a Lorentzian or 1/f. A simple analysis of the low-frequency noise data leads to the density of traps and their energy within the semiconductor bandgap. The level of noise in silicon JLT devices is lower than reported values on transistors fabricated using a top-down approach. This noise level can be significantly improved by improving the quality of dielectric and the channel interface. A micro-vacuum electron device based on silicon field emitters for cold cathode emission is also presented. The presented work utilizes vertical Si nanowires fabricated by means of self-assembly, standard lithography and etching techniques as field emitters in this dissertation. To obtain a high nanowire density, hence a high current density, a simple and inexpensive Langmuir Blodgett technique

Direct observation of single-charge-detection capability of nanowire field-effect transistors.

Science.gov (United States)

Salfi, J; Savelyev, I G; Blumin, M; Nair, S V; Ruda, H E

2010-10-01

A single localized charge can quench the luminescence of a semiconductor nanowire, but relatively little is known about the effect of single charges on the conductance of the nanowire. In one-dimensional nanostructures embedded in a material with a low dielectric permittivity, the Coulomb interaction and excitonic binding energy are much larger than the corresponding values when embedded in a material with the same dielectric permittivity. The stronger Coulomb interaction is also predicted to limit the carrier mobility in nanowires. Here, we experimentally isolate and study the effect of individual localized electrons on carrier transport in InAs nanowire field-effect transistors, and extract the equivalent charge sensitivity. In the low carrier density regime, the electrostatic potential produced by one electron can create an insulating weak link in an otherwise conducting nanowire field-effect transistor, modulating its conductance by as much as 4,200% at 31 K. The equivalent charge sensitivity, 4 × 10(-5) e Hz(-1/2) at 25 K and 6 × 10(-5) e Hz(-1/2) at 198 K, is orders of magnitude better than conventional field-effect transistors and nanoelectromechanical systems, and is just a factor of 20-30 away from the record sensitivity for state-of-the-art single-electron transistors operating below 4 K (ref. 8). This work demonstrates the feasibility of nanowire-based single-electron memories and illustrates a physical process of potential relevance for high performance chemical sensors. The charge-state-detection capability we demonstrate also makes the nanowire field-effect transistor a promising host system for impurities (which may be introduced intentionally or unintentionally) with potentially long spin lifetimes, because such transistors offer more sensitive spin-to-charge conversion readout than schemes based on conventional field-effect transistors.

Individual SnO2 nanowire transistors fabricated by the gold microwire mask method

International Nuclear Information System (INIS)

Sun Jia; Tang Qingxin; Lu Aixia; Jiang Xuejiao; Wan Qing

2009-01-01

A gold microwire mask method is developed for the fabrication of transistors based on single lightly Sb-doped SnO 2 nanowires. Damage of the nanowire's surface can be avoided without any thermal annealing and surface modification, which is very convenient for the fundamental electrical and photoelectric characterization of one-dimensional inorganic nanomaterials. Transport measurements of the individual SnO 2 nanowire devices demonstrate the high-performance n-type field effect transistor characteristics without significant hysteresis in the transfer curves. The current on/off ratio and the subthreshold swing of the nanowire transistors are found to be 10 6 and 240 mV/decade, respectively.

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

Science.gov (United States)

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

2007-08-01

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

Compact modeling of nanoscale triple-gate junctionless transistors covering drift-diffusion to quasi-ballistic carrier transport

Science.gov (United States)

Oproglidis, T. A.; Karatsori, T. A.; Barraud, S.; Ghibaudo, G.; Dimitriadis, C. A.

2018-04-01

In this work, we extend our analytical compact model for nanoscale junctionless triple-gate (JL TG) MOSFETs, capturing carrier transport from drift-diffusion to quasi-ballistic regime. This is based on a simple formulation of the low-field mobility extracted from experimental data using the Y-function method, taking into account the ballistic carrier motion and an increased carrier scattering in process-induced defects near the source/drain regions. The case of a Schottky junction in non-ideal ohmic contact at the drain side was also taken into account by modifying the threshold voltage and ideality factor of the JL transistor. The model is validated with experimental data for n-channel JL TG MOSFETs with channel length varying from 95 down to 25 nm. It can be easily implemented as a compact model for use in Spice circuit simulators.

Fabrication and characterization of novel gate-all-around polycrystalline silicon junctionless field-effect transistors with ultrathin horizontal tube-shape channel

Science.gov (United States)

Chang, You-Tai; Peng, Kang-Ping; Li, Pei-Wen; Lin, Horng-Chih

2018-04-01

In this paper, we report on a novel fabrication process for the production of junctionless field-effect transistors with an ultrathin polycrystalline silicon (poly-Si) tube channel in a gate-all-around (GAA) configuration. The core of the poly-Si tube channel is filled with either a silicon nitride or a silicon oxide layer, and the effects of the core layers on the device characteristics are evaluated. The devices show excellent switching performance, thanks to the combination of the ultrathin tube channel and the GAA structure. Hysteresis loops in the transfer characteristics of the nitride-core devices are observed, owing to the dynamic trapping of electrons in the nitride core.

Quantum ballistic analysis of transition metal dichalcogenides based double gate junctionless field effect transistor and its application in nano-biosensor

Science.gov (United States)

Shadman, Abir; Rahman, Ehsanur; Khosru, Quazi D. M.

2017-11-01

To reduce the thermal budget and the short channel effects in state of the art CMOS technology, Junctionless field effect transistor (JLFET) has been proposed in the literature. Numerous experimental, modeling, and simulation based works have been done on this new FET with bulk materials for various geometries until now. On the other hand, the two-dimensional layered material is considered as an alternative to current Si technology because of its ultra-thin body and high mobility. Very recently few simulation based works have been done on monolayer molybdenum disulfide based JLFET mainly to show the advantage of JLFET over conventional FET. However, no comprehensive simulation-based work has been done for double gate JLFET keeping in mind the prominent transition metal dichalcogenides (TMDC) to the authors' best knowledge. In this work, we have studied quantum ballistic drain current-gate voltage characteristics of such FETs within non-equilibrium Green's function (NEGF) framework. Our simulation results reveal that all these TMDC materials are viable options for implementing state of the art Junctionless MOSFET with emphasis on their performance at short gate lengths. Besides evaluating the prospect of TMDC materials in the digital logic application, the performance of Junctionless Double Gate trilayer TMDC heterostructure FET for the label-free electrical detection of biomolecules in dry environment has been investigated for the first time to the authors' best knowledge. The impact of charge neutral biomolecules on the electrical characteristics of the biosensor has been analyzed under dry environment situation. Our study shows that these materials could provide high sensitivity in the sub-threshold region as a channel material in nano-biosensor, a trend demonstrated by silicon on insulator FET sensor in the literature. Thus, going by the trend of replacing silicon with these novel materials in device level, TMDC heterostructure could be a viable alternative to

Nanowire field effect transistors principles and applications

CERN Document Server

Jeong, Yoon-Ha

2014-01-01

“Nanowire Field Effect Transistor: Basic Principles and Applications” places an emphasis on the application aspects of nanowire field effect transistors (NWFET). Device physics and electronics are discussed in a compact manner, together with the p-n junction diode and MOSFET, the former as an essential element in NWFET and the latter as a general background of the FET. During this discussion, the photo-diode, solar cell, LED, LD, DRAM, flash EEPROM and sensors are highlighted to pave the way for similar applications of NWFET. Modeling is discussed in close analogy and comparison with MOSFETs. Contributors focus on processing, electrostatic discharge (ESD) and application of NWFET. This includes coverage of solar and memory cells, biological and chemical sensors, displays and atomic scale light emitting diodes. Appropriate for scientists and engineers interested in acquiring a working knowledge of NWFET as well as graduate students specializing in this subject.

Dopant induced single electron tunneling within the sub-bands of single silicon NW tri-gate junctionless n-MOSFET

Science.gov (United States)

Uddin, Wasi; Georgiev, Yordan M.; Maity, Sarmistha; Das, Samaresh

2017-09-01

We report 1D electron transport of silicon junctionless tri-gate n-type transistor at 4.2 K. The step like curve observed in the current voltage characteristic suggests 1D transport. Besides the current steps for 1D transport, we found multiple spikes within individual steps, which we relate to inter-band single electron tunneling, mediated by the charged dopants available in the channel region. Clear Coulomb diamonds were observed in the stability diagram of the device. It is shown that a uniformly doped silicon nanowire can provide us the window for the single electron tunnelling. Back-gate versus front-gate color plot, where current is in a color scale, shows a crossover of the increased conduction region. This is a clear indication of the dopant-dopant interaction. It has been shown that back-gate biasing can be used to tune the coupling strength between the dopants.

Ballistic Spin Field Effect Transistor Based on Silicon Nanowires

Science.gov (United States)

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

2011-03-01

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

Vertical architecture for enhancement mode power transistors based on GaN nanowires

Science.gov (United States)

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

2016-05-01

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

Fabrication and characterization of junctionless carbon nanotube field effect transistor for cholesterol detection

Energy Technology Data Exchange (ETDEWEB)

Barik, Md. Abdul, E-mail: abdulnpl@gmail.com; Dutta, Jiten Ch. [Department of Electronics and Communication Engineering, Tezpur University, Napaam, Tezpur, Assam 784028 (India)

2014-08-04

We have reported fabrication and characterization of polyaniline (PANI)/zinc oxide (ZnO) membrane-based junctionless carbon nanotube field effect transistor deposited on indium tin oxide glass plate for the detection of cholesterol (0.5–22.2 mM). Cholesterol oxidase (ChOx) has been immobilized on the PANI/ZnO membrane by physical adsorption technique. Electrical response has been recorded using digital multimeter (Agilent 3458A) in the presence of phosphate buffer saline of 50 mM, pH 7.0, and 0.9% NaCl contained in a glass pot. The results of response studies for cholesterol reveal linearity as 0.5–16.6 mM and improved sensitivity of 60 mV/decade in good agreement with Nernstian limit ∼59.2 mV/decade. The life time of this sensor has been found up to 5 months and response time of 1 s. The limit of detection with regression coefficient (r) ∼ 0.998 and Michaelis-Menten constant (K{sub m}) were found to be ∼0.25 and 1.4 mM, respectively, indicating high affinity of ChOx to cholesterol. The results obtained in this work show negligible interference with glucose and urea.

Simulation for silicon-compatible InGaAs-based junctionless field-effect transistor using InP buffer layer

Science.gov (United States)

Seo, Jae Hwa; Cho, Seongjae; Kang, In Man

2013-10-01

In this paper, we present the optimized performances of indium gallium arsenide (InGaAs)-based compound junctionless field-effect transistors (JLFETs) using an indium phosphide (InP) buffer layer. The proposed InGaAs-InP material combination with little lattice mismatch provides a significant improvement in current drivability securing various potential applications. Device optimization is performed in terms of primary dc parameters and characterization is investigated by two-dimensional (2D) technology computer-aided design simulations. The optimization variables were the channel doping concentration (Nch), the buffer doping concentration (Nbf), and the channel thickness (Tch). For the optimally designed InGaAs JLFET, on-state current (Ion) of 325 µA µm-1, subthreshold swing (S) of 80 mV dec-1, and current ratio (Ion/Ioff) of 109 were obtained. In the end, the results are compared with the data of silicon (Si)-based JL MOSFETs to confirm the improvements.

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-11-30

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

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Transport and performance of a gate all around InAs nanowire transistor

International Nuclear Information System (INIS)

Alam, Khairul

2009-01-01

The transport physics and performance metrics of a gate all around an InAs nanowire transistor are studied using a three-dimensional quantum simulation. The transistor action of an InAs nanowire transistor occurs by modulating the transmission coefficient of the device. This action is different from a conventional metal-oxide-semiconductor field effect transistor, where the transistor action occurs by modulating the charge in the channel. The device has 82% tunneling current in the off-state and 81% thermal current in the on-state. The two current components become equal at a gate bias at which an approximate source-channel flat-band condition is achieved. Prior to this gate bias, the tunneling current dominates and the thermal current dominates beyond it. The device has an on/off current ratio of 7.84 × 10 5 and an inverse subthreshold slope of 63 mV dec −1 . The transistor operates in the quantum capacitance limit with a normalized transconductance value of 14.43 mS µm −1 , an intrinsic switching delay of 90.1675 fs, and an intrinsic unity current gain frequency of 6.8697 THz

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

Science.gov (United States)

Guerfi, Youssouf; Larrieu, Guilhem

2016-04-01

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

Transient performance estimation of charge plasma based negative capacitance junctionless tunnel FET

International Nuclear Information System (INIS)

Singh, Sangeeta; Kondekar, P. N.; Pal, Pawan

2016-01-01

We investigate the transient behavior of an n-type double gate negative capacitance junctionless tunnel field effect transistor (NC-JLTFET). The structure is realized by using the work-function engineering of metal electrodes over a heavily doped n + silicon channel and a ferroelectric gate stack to get negative capacitance behavior. The positive feedback in the electric dipoles of ferroelectric materials results in applied gate bias boosting. Various device transient parameters viz. transconductance, output resistance, output conductance, intrinsic gain, intrinsic gate delay, transconductance generation factor and unity gain frequency are analyzed using ac analysis of the device. To study the impact of the work-function variation of control and source gate on device performance, sensitivity analysis of the device has been carried out by varying these parameters. Simulation study reveals that it preserves inherent advantages of charge-plasma junctionless structure and exhibits improved transient behavior as well. (paper)

Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

Directory of Open Access Journals (Sweden)

Ping Feng

2014-09-01

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

Robust mode space approach for atomistic modeling of realistically large nanowire transistors

Science.gov (United States)

Huang, Jun Z.; Ilatikhameneh, Hesameddin; Povolotskyi, Michael; Klimeck, Gerhard

2018-01-01

Nanoelectronic transistors have reached 3D length scales in which the number of atoms is countable. Truly atomistic device representations are needed to capture the essential functionalities of the devices. Atomistic quantum transport simulations of realistically extended devices are, however, computationally very demanding. The widely used mode space (MS) approach can significantly reduce the numerical cost, but a good MS basis is usually very hard to obtain for atomistic full-band models. In this work, a robust and parallel algorithm is developed to optimize the MS basis for atomistic nanowires. This enables engineering-level, reliable tight binding non-equilibrium Green's function simulation of nanowire metal-oxide-semiconductor field-effect transistor (MOSFET) with a realistic cross section of 10 nm × 10 nm using a small computer cluster. This approach is applied to compare the performance of InGaAs and Si nanowire n-type MOSFETs (nMOSFETs) with various channel lengths and cross sections. Simulation results with full-band accuracy indicate that InGaAs nanowire nMOSFETs have no drive current advantage over their Si counterparts for cross sections up to about 10 nm × 10 nm.

The fabrication of ZnO nanowire field-effect transistors by roll-transfer printing

Science.gov (United States)

Chang, Yi-Kuei; Hong, Franklin Chau-Nan

2009-05-01

A method with the potential to fabricate large-area nanowire field-effect transistors (NW-FETs) was demonstrated in this study. Using a high-speed roller (20-80 cm min-1), transfer printing was successfully employed to transfer vertically aligned zinc oxide (ZnO) nanowires grown on a donor substrate to a polydimethylsiloxane (PDMS) stamp and then print the ordered ZnO nanowire arrays on the received substrate for the fabrication of NW-FETs. ZnO NW-FETs fabricated by this method exhibit high performances with a threshold voltage of around 0.25 V, a current on/off ratio as high as 105, a subthreshold slope of 360 mV/dec, and a field-effect mobility of around 90 cm2 V-1 s-1. The excellent device characteristics suggest that the roll-transfer printing technique, which is compatible with the roll-to-roll (R2R) process and operated in atmosphere, has a good potential for the high-speed fabrication of large-area nanowire transistors for flexible devices and flat panel displays.

The fabrication of ZnO nanowire field-effect transistors by roll-transfer printing

International Nuclear Information System (INIS)

Chang, Y-K; Hong, Franklin Chau-Nan

2009-01-01

A method with the potential to fabricate large-area nanowire field-effect transistors (NW-FETs) was demonstrated in this study. Using a high-speed roller (20-80 cm min -1 ), transfer printing was successfully employed to transfer vertically aligned zinc oxide (ZnO) nanowires grown on a donor substrate to a polydimethylsiloxane (PDMS) stamp and then print the ordered ZnO nanowire arrays on the received substrate for the fabrication of NW-FETs. ZnO NW-FETs fabricated by this method exhibit high performances with a threshold voltage of around 0.25 V, a current on/off ratio as high as 10 5 , a subthreshold slope of 360 mV/dec, and a field-effect mobility of around 90 cm 2 V -1 s -1 . The excellent device characteristics suggest that the roll-transfer printing technique, which is compatible with the roll-to-roll (R2R) process and operated in atmosphere, has a good potential for the high-speed fabrication of large-area nanowire transistors for flexible devices and flat panel displays.

The fabrication of ZnO nanowire field-effect transistors by roll-transfer printing

Energy Technology Data Exchange (ETDEWEB)

Chang, Y-K; Hong, Franklin Chau-Nan [Department of Chemical Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)], E-mail: hong@mail.ncku.edu.tw

2009-05-13

A method with the potential to fabricate large-area nanowire field-effect transistors (NW-FETs) was demonstrated in this study. Using a high-speed roller (20-80 cm min{sup -1}), transfer printing was successfully employed to transfer vertically aligned zinc oxide (ZnO) nanowires grown on a donor substrate to a polydimethylsiloxane (PDMS) stamp and then print the ordered ZnO nanowire arrays on the received substrate for the fabrication of NW-FETs. ZnO NW-FETs fabricated by this method exhibit high performances with a threshold voltage of around 0.25 V, a current on/off ratio as high as 10{sup 5}, a subthreshold slope of 360 mV/dec, and a field-effect mobility of around 90 cm{sup 2} V{sup -1} s{sup -1}. The excellent device characteristics suggest that the roll-transfer printing technique, which is compatible with the roll-to-roll (R2R) process and operated in atmosphere, has a good potential for the high-speed fabrication of large-area nanowire transistors for flexible devices and flat panel displays.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-12-23

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

A two-dimensional analytical subthreshold behavior model for junctionless dual-material cylindrical surrounding-gate MOSFETs

International Nuclear Information System (INIS)

Li Cong; Zhuang Yi-Qi; Zhang Li; Jin Gang

2014-01-01

A two-dimensional analytical subthreshold behavior model for junctionless dual-material cylindrical surrounding-gate (JLDMCSG) metal-oxide-semiconductor field-effect transistors (MOSFETs) is proposed. It is derived by solving the two-dimensional Poisson's equation in two continuous cylindrical regions with any simplifying assumption. Using this analytical model, the subthreshold characteristics of JLDMCSG MOSFETs are investigated in terms of channel electrostatic potential, horizontal electric field, and subthreshold current. Compared to junctionless single-material cylindrical surrounding-gate MOSFETs, JLDMCSG MOSFETs can effectively suppress short-channel effects and simultaneously improve carrier transport efficiency. It is found that the subthreshold current of JLDMCSG MOSFETs can be significantly reduced by adopting both a thin oxide and thin silicon channel. The accuracy of the analytical model is verified by its good agreement with the three-dimensional numerical simulator ISE TCAD

Effect of atomic layer deposition temperature on the performance of top-down ZnO nanowire transistors

Science.gov (United States)

2014-01-01

This paper studies the effect of atomic layer deposition (ALD) temperature on the performance of top-down ZnO nanowire transistors. Electrical characteristics are presented for 10-μm ZnO nanowire field-effect transistors (FETs) and for deposition temperatures in the range 120°C to 210°C. Well-behaved transistor output characteristics are obtained for all deposition temperatures. It is shown that the maximum field-effect mobility occurs for an ALD temperature of 190°C. This maximum field-effect mobility corresponds with a maximum Hall effect bulk mobility and with a ZnO film that is stoichiometric. The optimized transistors have a field-effect mobility of 10 cm2/V.s, which is approximately ten times higher than can typically be achieved in thin-film amorphous silicon transistors. Furthermore, simulations indicate that the drain current and field-effect mobility extraction are limited by the contact resistance. When the effects of contact resistance are de-embedded, a field-effect mobility of 129 cm2/V.s is obtained. This excellent result demonstrates the promise of top-down ZnO nanowire technology for a wide variety of applications such as high-performance thin-film electronics, flexible electronics, and biosensing. PMID:25276107

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

Science.gov (United States)

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

2012-07-25

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

The fabrication of ZnO nanowire field-effect transistors combining dielectrophoresis and hot-pressing

International Nuclear Information System (INIS)

Chang, Y-K; Chau-N H, Franklin

2009-01-01

Zinc oxide nanowire field-effect transistors (NW-FETs) were fabricated combining the dielectrophoresis (DEP) and the hot-pressing methods. DEP was used to position both ends of the nanowires on top of the source and the drain electrodes, respectively. Hot-pressing of nanowires on the electrodes was then employed to ensure good contacts between the nanowires and the electrodes. The good device performance achieved with our method of fabrication indicates that DEP combined with hot-pressing has the potential to be applied to the fabrication of flexible electronics on a roll-to-roll basis.

Improved performance of nanoscale junctionless tunnel field-effect transistor based on gate engineering approach

Science.gov (United States)

Molaei Imen Abadi, Rouzbeh; Sedigh Ziabari, Seyed Ali

2016-11-01

In this paper, a first qualitative study on the performance characteristics of dual-work function gate junctionless TFET (DWG-JLTFET) on the basis of energy band profile modulation is investigated. A dual-work function gate technique is used in a JLTFET in order to create a downward band bending on the source side similar to PNPN structure. Compared with the single-work function gate junctionless TFET (SWG-JLTFET), the numerical simulation results demonstrated that the DWG-JLTFET simultaneously optimizes the ON-state current, the OFF-state leakage current, and the threshold voltage and also improves average subthreshold slope. It is illustrated that if appropriate work functions are selected for the gate materials on the source side and the drain side, the JLTFET exhibits a considerably improved performance. Furthermore, the optimization design of the tunnel gate length ( L Tun) for the proposed DWG-JLTFET is studied. All the simulations are done in Silvaco TCAD for a channel length of 20 nm using the nonlocal band-to-band tunneling (BTBT) model.

Effects of piezoelectric potential on the transport characteristics of metal-ZnO nanowire-metal field effect transistor

KAUST Repository

Gao, Zhiyuan; Zhou, Jun; Gu, Yudong; Fei, Peng; Hao, Yue; Bao, Gang; Wang, Zhong Lin

2009-01-01

We have investigated the effects of piezoelectric potential in a ZnO nanowire on the transport characteristics of the nanowire based field effect transistor through numerical calculations and experimental observations. Under different straining

A radio-frequency single-electron transistor based on an InAs/InP heterostructure nanowire

DEFF Research Database (Denmark)

Nilsson, Henrik A.; Duty, Tim; Abay, Simon

2008-01-01

We demonstrate radio frequency single-electron transistors fabricated from epitaxially grown InAs/InP heterostructure nanowires. Two sets of double-barrier wires with different barrier thicknesses were grown. The wires were suspended 15 nm above a metal gate electrode. Electrical measurements...... on a high-resistance nanowire showed regularly spaced Coulomb oscillations at a gate voltage from −0.5 to at least 1.8 V. The charge sensitivity was measured to 32 µerms Hz−1/2 at 1.5 K. A low-resistance single-electron transistor showed regularly spaced oscillations only in a small gate-voltage region just...

Importance of the Debye screening length on nanowire field effect transistor sensors.

Science.gov (United States)

Stern, Eric; Wagner, Robin; Sigworth, Fred J; Breaker, Ronald; Fahmy, Tarek M; Reed, Mark A

2007-11-01

Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors.

Deformable Organic Nanowire Field-Effect Transistors.

Science.gov (United States)

Lee, Yeongjun; Oh, Jin Young; Kim, Taeho Roy; Gu, Xiaodan; Kim, Yeongin; Wang, Ging-Ji Nathan; Wu, Hung-Chin; Pfattner, Raphael; To, John W F; Katsumata, Toru; Son, Donghee; Kang, Jiheong; Matthews, James R; Niu, Weijun; He, Mingqian; Sinclair, Robert; Cui, Yi; Tok, Jeffery B-H; Lee, Tae-Woo; Bao, Zhenan

2018-02-01

Deformable electronic devices that are impervious to mechanical influence when mounted on surfaces of dynamically changing soft matters have great potential for next-generation implantable bioelectronic devices. Here, deformable field-effect transistors (FETs) composed of single organic nanowires (NWs) as the semiconductor are presented. The NWs are composed of fused thiophene diketopyrrolopyrrole based polymer semiconductor and high-molecular-weight polyethylene oxide as both the molecular binder and deformability enhancer. The obtained transistors show high field-effect mobility >8 cm 2 V -1 s -1 with poly(vinylidenefluoride-co-trifluoroethylene) polymer dielectric and can easily be deformed by applied strains (both 100% tensile and compressive strains). The electrical reliability and mechanical durability of the NWs can be significantly enhanced by forming serpentine-like structures of the NWs. Remarkably, the fully deformable NW FETs withstand 3D volume changes (>1700% and reverting back to original state) of a rubber balloon with constant current output, on the surface of which it is attached. The deformable transistors can robustly operate without noticeable degradation on a mechanically dynamic soft matter surface, e.g., a pulsating balloon (pulse rate: 40 min -1 (0.67 Hz) and 40% volume expansion) that mimics a beating heart, which underscores its potential for future biomedical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

International Nuclear Information System (INIS)

Bindal, Ahmet; Hamedi-Hagh, Sotoudeh

2007-01-01

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

Polymer chain alignment and transistor properties of nanochannel-templated poly(3-hexylthiophene) nanowires

Science.gov (United States)

Oh, Seungjun; Hayakawa, Ryoma; Pan, Chengjun; Sugiyasu, Kazunori; Wakayama, Yutaka

2016-08-01

Nanowires of semiconducting poly(3-hexylthiophene) (P3HT) were produced by a nanochannel-template technique. Polymer chain alignment in P3HT nanowires was investigated as a function of nanochannel widths (W) and polymer chain lengths (L). We found that the ratio between chain length and channel width (L/W) was a key parameter as regards promoting polymer chain alignment. Clear dichroism was observed in polarized ultraviolet-visible (UV-Vis) absorption spectra only at a ratio of approximately L/W = 2, indicating that the L/W ratio must be optimized to achieve uniaxial chain alignment in the nanochannel direction. We speculate that an appropriate L/W ratio is effective in confining the geometries and conformations of polymer chains. This discussion was supported by theoretical simulations based on molecular dynamics. That is, the geometry of the polymer chains, including the distance and tilting angles of the chains in relation to the nanochannel surface, was dominant in determining the longitudinal alignment along the nanochannels. Thus prepared highly aligned polymer nanowire is advantageous for electrical carrier transport and has great potential for improving the device performance of field-effect transistors. In fact, a one-order improvement in carrier mobility was observed in a P3HT nanowire transistor.

Analytical model of nanoscale junctionless transistors towards controlling of short channel effects through source/drain underlap and channel thickness engineering

Science.gov (United States)

Roy, Debapriya; Biswas, Abhijit

2018-01-01

We develop a 2D analytical subthreshold model for nanoscale double-gate junctionless transistors (DGJLTs) with gate-source/drain underlap. The model is validated using well-calibrated TCAD simulation deck obtained by comparing experimental data in the literature. To analyze and control short-channel effects, we calculate the threshold voltage, drain induced barrier lowering (DIBL) and subthreshold swing of DGJLTs using our model and compare them with corresponding simulation value at channel length of 20 nm with channel thickness tSi ranging 5-10 nm, gate-source/drain underlap (LSD) values 0-7 nm and source/drain doping concentrations (NSD) ranging 5-12 × 1018 cm-3. As tSi reduces from 10 to 5 nm DIBL drops down from 42.5 to 0.42 mV/V at NSD = 1019 cm-3 and LSD = 5 nm in contrast to decrement from 71 to 4.57 mV/V without underlap. For a lower tSiDIBL increases marginally with increasing NSD. The subthreshold swing reduces more rapidly with thinning of channel thickness rather than increasing LSD or decreasing NSD.

Nanowire transistors physics of devices and materials in one dimension

CERN Document Server

Colinge, Jean-Pierre

2016-01-01

From quantum mechanical concepts to practical circuit applications, this book presents a self-contained and up-to-date account of the physics and technology of nanowire semiconductor devices. It includes a unified account of the critical ideas central to low-dimensional physics and transistor physics which equips readers with a common framework and language to accelerate scientific and technological developments across the two fields. Detailed descriptions of novel quantum mechanical effects such as quantum current oscillations, the metal-to-semiconductor transition and the transition from classical transistor to single-electron transistor operation are described in detail, in addition to real-world applications in the fields of nanoelectronics, biomedical sensing techniques, and advanced semiconductor research. Including numerous illustrations to help readers understand these phenomena, this is an essential resource for researchers and professional engineers working on semiconductor devices and materials in ...

ON current enhancement of nanowire Schottky barrier tunnel field effect transistors

Science.gov (United States)

Takei, Kohei; Hashimoto, Shuichiro; Sun, Jing; Zhang, Xu; Asada, Shuhei; Xu, Taiyu; Matsukawa, Takashi; Masahara, Meishoku; Watanabe, Takanobu

2016-04-01

Silicon nanowire Schottky barrier tunnel field effect transistors (NW-SBTFETs) are promising structures for high performance devices. In this study, we fabricated NW-SBTFETs to investigate the effect of nanowire structure on the device characteristics. The NW-SBTFETs were operated with a backgate bias, and the experimental results demonstrate that the ON current density is enhanced by narrowing the width of the nanowire. We confirmed using the Fowler-Nordheim plot that the drain current in the ON state mainly comprises the quantum tunneling component through the Schottky barrier. Comparison with a technology computer aided design (TCAD) simulation revealed that the enhancement is attributed to the electric field concentration at the corners of cross-section of the NW. The study findings suggest an effective approach to securing the ON current by Schottky barrier width modulation.

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.

Numerical analysis of band tails in nanowires and their effects on the performance of tunneling field-effect transistors

Science.gov (United States)

Tanaka, Takahisa; Uchida, Ken

2018-06-01

Band tails in heavily doped semiconductors are one of the important parameters that determine transfer characteristics of tunneling field-effect transistors. In this study, doping concentration and doing profile dependences of band tails in heavily doped Si nanowires were analyzed by a nonequilibrium Green function method. From the calculated band tails, transfer characteristics of nanowire tunnel field-effect transistors were numerically analyzed by Wentzel–Kramer–Brillouin approximation with exponential barriers. The calculated transfer characteristics demonstrate that the band tails induced by dopants degrade the subthreshold slopes of Si nanowires from 5 to 56 mV/dec in the worst case. On the other hand, surface doping leads to a high drain current while maintaining a small subthreshold slope.

A Robust Highly Aligned DNA Nanowire Array-Enabled Lithography for Graphene Nanoribbon Transistors.

Science.gov (United States)

Kang, Seok Hee; Hwang, Wan Sik; Lin, Zhiqun; Kwon, Se Hun; Hong, Suck Won

2015-12-09

Because of its excellent charge carrier mobility at the Dirac point, graphene possesses exceptional properties for high-performance devices. Of particular interest is the potential use of graphene nanoribbons or graphene nanomesh for field-effect transistors. Herein, highly aligned DNA nanowire arrays were crafted by flow-assisted self-assembly of a drop of DNA aqueous solution on a flat polymer substrate. Subsequently, they were exploited as "ink" and transfer-printed on chemical vapor deposited (CVD)-grown graphene substrate. The oriented DNA nanowires served as the lithographic resist for selective removal of graphene, forming highly aligned graphene nanoribbons. Intriguingly, these graphene nanoribbons can be readily produced over a large area (i.e., millimeter scale) with a high degree of feature-size controllability and a low level of defects, rendering the fabrication of flexible two terminal devices and field-effect transistors.

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...

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 woven fiber organic electrochemical transistors based on polypyrrole nanowires/reduced graphene oxide composites for glucose sensing.

Science.gov (United States)

Wang, Yuedan; Qing, Xing; Zhou, Quan; Zhang, Yang; Liu, Qiongzhen; Liu, Ke; Wang, Wenwen; Li, Mufang; Lu, Zhentan; Chen, Yuanli; Wang, Dong

2017-09-15

Novel woven fiber organic electrochemical transistors based on polypyrrole (PPy) nanowires and reduced graphene oxide (rGO) have been prepared. SEM revealed that the introduction of rGO nanosheets could induce the growth and increase the amount of PPy nanowires. Moreover, it could enhance the electrical performance of fiber transistors. The hybrid transistors showed high on/off ratio of 10 2 , fast switch speed, and long cycling stability. The glucose sensors based on the fiber organic electrochemical transistors have also been investigated, which exhibited outstanding sensitivity, as high as 0.773 NCR/decade, with a response time as fast as 0.5s, a linear range of 1nM to 5μM, a low detection concentration as well as good repeatability. In addition, the glucose could be selectively detected in the presence of ascorbic acid and uric acid interferences. The reliability of the proposed glucose sensor was evaluated in real samples of rabbit blood. All the results indicate that the novel fiber transistors pave the way for portable and wearable electronics devices, which have a promising future for healthcare and biological applications. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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

2018-02-01

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

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.

Planar junctionless phototransistor: A potential high-performance and low-cost device for optical-communications

Science.gov (United States)

Ferhati, H.; Djeffal, F.

2017-12-01

In this paper, a new junctionless optical controlled field effect transistor (JL-OCFET) and its comprehensive theoretical model is proposed to achieve high optical performance and low cost fabrication process. Exhaustive study of the device characteristics and comparison between the proposed junctionless design and the conventional inversion mode structure (IM-OCFET) for similar dimensions are performed. Our investigation reveals that the proposed design exhibits an outstanding capability to be an alternative to the IM-OCFET due to the high performance and the weak signal detection benefit offered by this design. Moreover, the developed analytical expressions are exploited to formulate the objective functions to optimize the device performance using Genetic Algorithms (GAs) approach. The optimized JL-OCFET not only demonstrates good performance in terms of derived drain current and responsivity, but also exhibits superior signal to noise ratio, low power consumption, high-sensitivity, high ION/IOFF ratio and high-detectivity as compared to the conventional IM-OCFET counterpart. These characteristics make the optimized JL-OCFET potentially suitable for developing low cost and ultrasensitive photodetectors for high-performance and low cost inter-chips data communication applications.

The influence of atmosphere on performance of pure-phase WZ and ZB InAs nanowire transistors.

Science.gov (United States)

Ullah, Abu Rifat; Joyce, Hannah J; Tan, Hoe; Jagadish, Chennupati; Micolich, Adam P

2017-09-21

We compare the characteristics of phase-pure MOCVD grown ZB and WZ InAs nanowire transistors in several atmospheres: air, dry pure N₂ and O₂, and N₂ bubbled through liquid H₂O and alcohols to identify whether phase-related structural/surface differences affect their response. Both WZ and ZB give poor gate characteristics in dry state. Adsorption of polar species reduces off-current by 2-3 orders of magnitude, increases on-off ratio and significantly reduces sub-threshold slope. The key difference is the greater sensitivity of WZ to low adsorbate level. We attribute this to facet structure and its influence on the separation between conduction electrons and surface adsorption sites. We highlight the important role adsorbed species play in nanowire device characterisation. WZ is commonly thought superior to ZB in InAs nanowire transistors. We show this is an artefact of the moderate humidity found in ambient laboratory conditions: WZ and ZB perform equally poorly in the dry gas limit yet equally well in the wet gas limit. We also highlight the vital role density-lowering disorder has in improving gate characteristics, be it stacking faults in mixed-phase WZ or surface adsorbates in pure-phase nanowires. © 2017 IOP Publishing Ltd.

Effects of piezoelectric potential on the transport characteristics of metal-ZnO nanowire-metal field effect transistor

KAUST Repository

Gao, Zhiyuan

2009-01-01

We have investigated the effects of piezoelectric potential in a ZnO nanowire on the transport characteristics of the nanowire based field effect transistor through numerical calculations and experimental observations. Under different straining conditions including stretching, compressing, twisting, and their combination, a piezoelectric potential is created throughout the nanowire to modulatealternate the transport property of the metal-ZnO nanowire contacts, resulting in a switch between symmetric and asymmetric contacts at the two ends, or even turning an Ohmic contact type into a diode. The commonly observed natural rectifying behavior of the as-fabricated ZnO nanowire can be attributed to the strain that was unpurposely created in the nanowire during device fabrication and material handling. This work provides further evidence on piezopotential governed electronic transport and devices, e.g., piezotronics.

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

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

Science.gov (United States)

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

2017-12-01

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

Photo-assisted hysteresis of electronic transport for ZnO nanowire transistors

Science.gov (United States)

Du, Qianqian; Ye, Jiandong; Xu, Zhonghua; Zhu, Shunming; Tang, Kun; Gu, Shulin; Zheng, Youdou

2018-03-01

Recently, ZnO nanowire field effect transistors (FETs) have received renewed interest due to their extraordinary low dimensionality and high sensitivity to external chemical environments and illumination conditions. These prominent properties have promising potential in nanoscale chemical and photo-sensors. In this article, we have fabricated ZnO nanowire FETs and have found hysteresis behavior in their transfer characteristics. The mechanism and dynamics of the hysteresis phenomena have been investigated in detail by varying the sweeping rate and range of the gate bias with and without light irradiation. Significantly, light irradiation is of great importance on charge trapping by regulating adsorption and desorption of oxygen at the interface of ZnO/SiO2. Carriers excited by light irradiation can dramatically promote trapping/detrapping processes. With the assistance of light illumination, we have demonstrated a photon-assisted nonvolatile memory which employs the ZnO nanowire FET. The device exhibits reliable programming/erasing operations and a large on/off ratio. The proposed proto-type memory has thus provided a possible novel path for creating a memory functionality to other low-dimensional material systems.

Are Nanotube Architectures More Advantageous Than Nanowire Architectures For Field Effect Transistors?

KAUST Repository

Fahad, Hossain M.

2012-06-27

Decade long research in 1D nanowire field effect transistors (FET) shows although it has ultra-low off-state leakage current and a single device uses a very small area, its drive current generation per device is extremely low. Thus it requires arrays of nanowires to be integrated together to achieve appreciable amount of current necessary for high performance computation causing an area penalty and compromised functionality. Here we show that a FET with a nanotube architecture and core-shell gate stacks is capable of achieving the desirable leakage characteristics of the nanowire FET while generating a much larger drive current with area efficiency. The core-shell gate stacks of silicon nanotube FETs tighten the electrostatic control and enable volume inversion mode operation leading to improved short channel behavior and enhanced performance. Our comparative study is based on semi-classical transport models with quantum confinement effects which offers new opportunity for future generation high performance computation.

The influence of atmosphere on the performance of pure-phase WZ and ZB InAs nanowire transistors

Science.gov (United States)

Ullah, A. R.; Joyce, H. J.; Tan, H. H.; Jagadish, C.; Micolich, A. P.

2017-11-01

We compare the characteristics of phase-pure MOCVD grown ZB and WZ InAs nanowire transistors in several atmospheres: air, dry pure N2 and O2, and N2 bubbled through liquid H2O and alcohols to identify whether phase-related structural/surface differences affect their response. Both WZ and ZB give poor gate characteristics in dry state. Adsorption of polar species reduces off-current by 2-3 orders of magnitude, increases on-off ratio and significantly reduces sub-threshold slope. The key difference is the greater sensitivity of WZ to low adsorbate level. We attribute this to facet structure and its influence on the separation between conduction electrons and surface adsorption sites. We highlight the important role adsorbed species play in nanowire device characterisation. WZ is commonly thought superior to ZB in InAs nanowire transistors. We show this is an artefact of the moderate humidity found in ambient laboratory conditions: WZ and ZB perform equally poorly in the dry gas limit yet equally well in the wet gas limit. We also highlight the vital role density-lowering disorder has in improving gate characteristics, be it stacking faults in mixed-phase WZ or surface adsorbates in pure-phase nanowires.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

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

International Nuclear Information System (INIS)

Shariati, Mohsen

2017-01-01

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

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

International Nuclear Information System (INIS)

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

2010-01-01

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

The optimal design of 15 nm gate-length junctionless SOI FinFETs for reducing leakage current

International Nuclear Information System (INIS)

Liu, Xi; Wu, Meile; Jin, Xiaoshi; Chuai, Rongyan; Lee, Jung-Hee; Lee, Jong-Ho

2013-01-01

Junctionless (JL) transistors need to be heavily doped to have large drain current in the ON-state, which engenders the effect of band-to-band tunneling (BTBT) in the OFF-state simultaneously. It causes an obvious increase of the leakage current in the OFF-state. This paper presents an effective method of reducing the leakage current by changing the geometrical shape and dimension of the oxide layer under the edge of the gate. The optimal design of 15 nm gate-length JL silicon-on-insulator FinFETs with the triple-gate structure is performed for reducing the effect of BTBT through simulation and analysis by this means. (paper)

Single ZnO nanowire-PZT optothermal field effect transistors.

Science.gov (United States)

Hsieh, Chun-Yi; Lu, Meng-Lin; Chen, Ju-Ying; Chen, Yung-Ting; Chen, Yang-Fang; Shih, Wan Y; Shih, Wei-Heng

2012-09-07

A new type of pyroelectric field effect transistor based on a composite consisting of single zinc oxide nanowire and lead zirconate titanate (ZnO NW-PZT) has been developed. Under infrared (IR) laser illumination, the transconductance of the ZnO NW can be modulated by optothermal gating. The drain current can be increased or decreased by IR illumination depending on the polarization orientation of the Pb(Zr(0.3)Ti(0.7))O(3) (PZT) substrate. Furthermore, by combining the photocurrent behavior in the UV range and the optothermal gating effect in the IR range, the wide spectrum of response of current by light offers a variety of opportunities for nanoscale optoelectronic devices.

Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

KAUST Repository

Caraveo-Frescas, J. A.

2013-11-25

p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p-type oxide semiconductor processed at similar temperature. Compared to thin film transistors, the SnO nanowire transistors exhibit five times higher mobility and one order of magnitude lower subthreshold swing. The SnO nanowire transistors show three times lower threshold voltages (−1 V) than the best reported SnO thin film transistors and fifteen times smaller than p-type Cu 2O nanowire transistors. Gate dielectric and process temperature are critical to achieving such performance.

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.)

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

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

Science.gov (United States)

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

2012-02-01

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

Silicon nanowire field-effect transistors for the detection of proteins

Science.gov (United States)

Madler, Carsten

In this dissertation I present results on our efforts to increase the sensitivity and selectivity of silicon nanowire ion-sensitive field-effect transistors for the detection of biomarkers, as well as a novel method for wireless power transfer based on metamaterial rectennas for their potential use as implantable sensors. The sensing scheme is based on changes in the conductance of the semiconducting nanowires upon binding of charged entities to the surface, which induces a field-effect. Monitoring the differential conductance thus provides information of the selective binding of biological molecules of interest to previously covalently linked counterparts on the nanowire surface. In order to improve on the performance of the nanowire sensing, we devised and fabricated a nanowire Wheatstone bridge, which allows canceling out of signal drift due to thermal fluctuations and dynamics of fluid flow. We showed that balancing the bridge significantly improves the signal-to-noise ratio. Further, we demonstrated the sensing of novel melanoma biomarker TROY at clinically relevant concentrations and distinguished it from nonspecific binding by comparing the reaction kinetics. For increased sensitivity, an amplification method was employed using an enzyme which catalyzes a signal-generating reaction by changing the redox potential of a redox pair. In addition, we investigated the electric double layer, which forms around charges in an electrolytic solution. It causes electrostatic screening of the proteins of interest, which puts a fundamental limitation on the biomarker detection in solutions with high salt concentrations, such as blood. We solved the coupled Nernst-Planck and Poisson equations for the electrolyte under influence of an oscillating electric field and discovered oscillations of the counterion concentration at a characteristic frequency. In addition to exploring different methods for improved sensing capabilities, we studied an innovative method to supply power

EDITORIAL: Reigniting innovation in the transistor Reigniting innovation in the transistor

Science.gov (United States)

Demming, Anna

2012-09-01

Today the transistor is integral to the electronic circuitry that wires our lives. When Bardeen and Brattain first observed an amplified signal by connecting electrodes to a germanium crystal they saw that their 'semiconductor triode' could prove a useful alternative to the more cumbersome vacuum tubes used at the time [1]. But it was perhaps William Schottky who recognized the extent of the transistor's potential. A basic transistor has three or more terminals and current across one pair of terminals can switch or amplify current through another pair. Bardeen, Brattain and Schottky were jointly awarded a Nobel Prize in 1956 'for their researches on semiconductors and their discovery of the transistor effect' [2]. Since then many new forms of the transistor have been developed and understanding of the underlying properties is constantly advancing. In this issue Chen and Shih and colleagues at Taiwan National University and Drexel University report a pyroelectrics transistor. They show how a novel optothermal gating mechanism can modulate the current, allowing a range of developments in nanoscale optoelectronics and wireless devices [3]. The explosion of interest in nanoscale devices in the 1990s inspired electronics researchers to look for new systems that can act as transistors, such as carbon nanotube [4] and silicon nanowire [5] transistors. Generally these transistors function by raising and lowering an energy barrier of kBT -1, but researchers in the US and Canada have demonstrated that the quantum interference between two electronic pathways through aromatic molecules can also modulate the current flow [6]. The device has advantages for further miniaturization where energy dissipation in conventional systems may eventually cause complications. Interest in transistor technology has also led to advances in fabrication techniques for achieving high production quantities, such as printing [7]. Researchers in Florida in the US demonstrated field effect transistor

Electrical characterization of Ω-gated uniaxial tensile strained Si nanowire-array metal-oxide-semiconductor field effect transistors with - and channel orientations

International Nuclear Information System (INIS)

Habicht, Stefan; Feste, Sebastian; Zhao, Qing-Tai; Buca, Dan; Mantl, Siegfried

2012-01-01

Nanowire-array metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated along and crystal directions on (001) un-/strained silicon-on-insulator substrates. Lateral strain relaxation through patterning was employed to transform biaxial tensile strain into uniaxial tensile strain along the nanowire. Devices feature ideal subthreshold swings and maximum on-current/off-current ratios of 10 11 for n and p-type transistors on both substrates. Electron and hole mobilities were extracted by split C–V method. For p-MOSFETs an increased mobility is observed for channel direction devices compared to devices. The n-MOSFETs showed a 45% increased electron mobility compared to devices. The comparison of strained and unstrained n-MOSFETs along and clearly demonstrates improved electron mobilities for strained channels of both channel orientations.

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

Science.gov (United States)

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

2014-05-21

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

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.

Analysis of nanowire transistor based nitrogen dioxide gas sensor – A simulation study

Directory of Open Access Journals (Sweden)

Gaurav Saxena

2015-06-01

Full Text Available Sensors sensitivity, selectivity and stability has always been a prime design concern for gas sensors designers. Modeling and simulation of gas sensors aids the designers in improving their performance. In this paper, different routes for the modeling and simulation of a semiconducting gas sensor is presented. Subsequently, by employing one of the route, the response of Zinc Oxide nanowire transistor towards nitrogen dioxide ambient is simulated. In addition to the sensing mechanism, simulation study of gas species desorption by applying a recovery voltage is also presented.

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

Science.gov (United States)

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

2017-01-01

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

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.

Unlocking the Origin of Superior Performance of a Si-Ge Core-Shell Nanowire Quantum Dot Field Effect Transistor.

Science.gov (United States)

Dhungana, Kamal B; Jaishi, Meghnath; Pati, Ranjit

2016-07-13

The sustained advancement in semiconducting core-shell nanowire technology has unlocked a tantalizing route for making next generation field effect transistor (FET). Understanding how to control carrier mobility of these nanowire channels by applying a gate field is the key to developing a high performance FET. Herein, we have identified the switching mechanism responsible for the superior performance of a Si-Ge core-shell nanowire quantum dot FET over its homogeneous Si counterpart. A quantum transport approach is used to investigate the gate-field modulated switching behavior in electronic current for ultranarrow Si and Si-Ge core-shell nanowire quantum dot FETs. Our calculations reveal that for the ON state, the gate-field induced transverse localization of the wave function restricts the carrier transport to the outer (shell) layer with the pz orbitals providing the pathway for tunneling of electrons in the channels. The higher ON state current in the Si-Ge core-shell nanowire FET is attributed to the pz orbitals that are distributed over the entire channel; in the case of Si nanowire, the participating pz orbital is restricted to a few Si atoms in the channel resulting in a smaller tunneling current. Within the gate bias range considered here, the transconductance is found to be substantially higher in the case of a Si-Ge core-shell nanowire FET than in a Si nanowire FET, which suggests a much higher mobility in the Si-Ge nanowire device.

Exploring the Short-Channel Characteristics of Asymmetric Junctionless Double-Gate Silicon-on-Nothing MOSFET

Science.gov (United States)

Saha, Priyanka; Banerjee, Pritha; Dash, Dinesh Kumar; Sarkar, Subir Kumar

2018-03-01

This paper presents an analytical model of an asymmetric junctionless double-gate (asymmetric DGJL) silicon-on-nothing metal-oxide-semiconductor field-effect transistor (MOSFET). Solving the 2-D Poisson's equation, the expressions for center potential and threshold voltage are calculated. In addition, the response of the device toward the various short-channel effects like hot carrier effect, drain-induced barrier lowering and threshold voltage roll-off has also been examined along with subthreshold swing and drain current characteristics. Performance analysis of the present model is also demonstrated by comparing its short-channel behavior with conventional DGJL MOSFET. The effect of variation of the device features due to the variation of device parameters is also studied. The simulated results obtained using 2D device simulator, namely ATLAS, are in good agreement with the analytical results, hence validating our derived model.

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

KAUST Repository

Huang, Ruo-Gu; Tham, Douglas; Wang, Dunwei; Heath, James R.

2011-01-01

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.

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.

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

Science.gov (United States)

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

2013-05-01

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

The detection of electron-beam-induced current in junctionless semiconductor

International Nuclear Information System (INIS)

Tan, Chee Chin; Ong, Vincent K. S.

2010-01-01

The scanning electron microscope is a versatile tool and its electron beam techniques have been widely used in semiconductor material and device characterizations. One of these electron beam techniques is the electron-beam-induced current (EBIC) technique. One of the limitations of the conventional EBIC technique is that it requires charge collecting junctions which may not be readily available in junctionless samples such as bare substrates unless some special sample preparation procedure such as the fabrication of a diffused junction is done on the junctionless sample. In this paper, the technique of detecting EBIC current in junctionless samples with the use of a two-point probe is presented. It is found that the EBIC current is independent from its physical parameter when the sample thickness is greater than 4L; the width to the right of probe 2 and the width to the left of probe 1 are greater than 2L and 8L, respectively. The parameters affecting this technique of detecting the EBIC current such as the depth of the generation volume, probe spacing, and the applied bias are also discussed in this paper. A commercially available two-dimensional device simulator was used to verify this technique.

Interface studies of N2 plasma-treated ZnSnO nanowire transistors using low-frequency noise measurements

International Nuclear Information System (INIS)

Kim, Seongmin; Janes, David B; Kim, Hwansoo; Ju, Sanghyun

2013-01-01

Due to the large surface-to-volume ratio of nanowires, the quality of nanowire–insulator interfaces as well as the nanowire surface characteristics significantly influence the electrical characteristics of nanowire transistors (NWTs). To improve the electrical characteristics by doping or post-processing, it is important to evaluate the interface characteristics and stability of NWTs. In this study, we have synthesized ZnSnO (ZTO) nanowires using the chemical vapor deposition method, characterized the composition of ZTO nanowires using x-ray photoelectron spectroscopy, and fabricated ZTO NWTs. We have characterized the current–voltage characteristics and low-frequency noise of ZTO NWTs in order to investigate the effects of interface states on subthreshold slope (SS) and the noise before and after N 2 plasma treatments. The as-fabricated device exhibited a SS of 0.29 V/dec and Hooge parameter of ∼1.20 × 10 −2 . Upon N 2 plasma treatment with N 2 gas flow rate of 40 sccm (20 sccm), the SS improved to 0.12 V/dec (0.21 V/dec) and the Hooge parameter decreased to ∼4.99 × 10 −3 (8.14 × 10 −3 ). The interface trap densities inferred from both SS and low-frequency noise decrease upon plasma treatment, with the highest flow rate yielding the smallest trap density. These results demonstrate that the N 2 plasma treatment decreases the interface trap states and defects on ZTO nanowires, thereby enabling the fabrication of high-quality nanowire interfaces. (paper)

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Highly stable field emission from ZnO nanowire field emitters controlled by an amorphous indium–gallium–zinc-oxide thin film transistor

Science.gov (United States)

Li, Xiaojie; Wang, Ying; Zhang, Zhipeng; Ou, Hai; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

2018-04-01

Lowering the driving voltage and improving the stability of nanowire field emitters are essential for them to be applied in devices. In this study the characteristics of zinc oxide (ZnO) nanowire field emitter arrays (FEAs) controlled by an amorphous indium–gallium–zinc-oxide thin film transistor (a-IGZO TFT) were studied. A low driving voltage along with stabilization of the field emission current were achieved. Modulation of field emission currents up to three orders of magnitude was achieved at a gate voltage of 0–32 V for a constant anode voltage. Additionally, a-IGZO TFT control can dramatically reduce the emission current fluctuation (i.e., from 46.11 to 1.79% at an emission current of ∼3.7 µA). Both the a-IGZO TFT and ZnO nanowire FEAs were prepared on glass substrates in our research, demonstrating the feasibility of realizing large area a-IGZO TFT-controlled ZnO nanowire FEAs.

Memristive behavior in a junctionless flash memory cell

Energy Technology Data Exchange (ETDEWEB)

Orak, Ikram [Vocational School of Health Services, Bingöl University, 12000 Bingöl (Turkey); Department of Physics, Faculty of Science and Art, Bingöl University, 12000 Bingöl (Turkey); Ürel, Mustafa; Dana, Aykutlu, E-mail: aykutlu@unam.bilkent.edu.tr [UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Bakan, Gokhan [Faculty of Engineering, Antalya International University, 07190 Antalya (Turkey)

2015-06-08

We report charge storage based memristive operation of a junctionless thin film flash memory cell when it is operated as a two terminal device by grounding the gate. Unlike memristors based on nanoionics, the presented device mode, which we refer to as the flashristor mode, potentially allows greater control over the memristive properties, allowing rational design. The mode is demonstrated using a depletion type n-channel ZnO transistor grown by atomic layer deposition (ALD), with HfO{sub 2} as the tunnel dielectric, Al{sub 2}O{sub 3} as the control dielectric, and non-stoichiometric silicon nitride as the charge storage layer. The device exhibits the pinched hysteresis of a memristor and in the unoptimized device, R{sub off}/R{sub on} ratios of about 3 are presented with low operating voltages below 5 V. A simplified model predicts R{sub off}/R{sub on} ratios can be improved significantly by adjusting the native threshold voltage of the devices. The repeatability of the resistive switching is excellent and devices exhibit 10{sup 6 }s retention time, which can, in principle, be improved by engineering the gate stack and storage layer properties. The flashristor mode can find use in analog information processing applications, such as neuromorphic computing, where well-behaving and highly repeatable memristive properties are desirable.

3D NANOTUBE FIELD EFFECT TRANSISTORS FOR HYBRID HIGH-PERFORMANCE AND LOW-POWER OPERATION WITH HIGH CHIP-AREA EFFICIENCY

KAUST Repository

Fahad, Hossain M.

2014-03-01

scaling on silicon, the amount of current generated per device has to be increased while keeping short channel effects and off-state leakage at bay. The objective of this doctoral thesis is the investigation of an innovative vertical silicon based architecture called the silicon nanotube field effect transistor (Si NTFET). This topology incorporates a dual inner/outer core/shell gate stack strategy to control the volume inversion properties in a hollow silicon 1D quasi-nanotube under a tight electrostatic configuration. Together with vertically aligned source and drain, the Si NTFET is capable of very high on-state performance (drive current) in an area-efficient configuration as opposed to arrays of gate-all-around nanowires, while maintaining leakage characteristics similar to a single nanowire. Such a device architecture offsets the need of device arraying that is needed with fin and nanowire architectures. Extensive simulations are used to validate the potential benefits of Si NTFETs over GAA NWFETs on a variety of platforms such as conventional MOSFETs, tunnel FETs, junction-less FETs. This thesis demonstrates a novel CMOS compatible process flow to fabricate vertical nanotube transistors that offer a variety of advantages such as lithography-independent gate length definition, integration of epitaxially grown silicon nanotubes with spacer based gate dielectrics and abrupt in-situ doped source/drain junctions. Experimental measurement data will showcase the various materials and processing challenges in fabricating these devices. Finally, an extension of this work to topologically transformed wavy channel FinFETs is also demonstrated keeping in line with the theme of area efficient high-performance electronics.

Analysis of surface states in ZnO nanowire field effect transistors

International Nuclear Information System (INIS)

Shao, Ye; Yoon, Jongwon; Kim, Hyeongnam; Lee, Takhee; Lu, Wu

2014-01-01

Highlights: • The electron transport in ZnO nanowire FETs is space charged limited below a trap temperature. • Metallic contacts to ZnO nanowires exhibit non-linear behavior with a Schottky barrier height of ∼0.35 eV. • The surface state density is in the range of 1.04 × 10 10 –1.24 × 10 10 /cm 2 . • The trap activation energy is ∼0.26 eV. - Abstract: Nanowires (NWs) have attracted considerable interests for scaled electronic and optoelectronic device applications. However, NW based semiconductor devices normally suffer from surface states due to the existence of dangling bonds or surface reconstruction. Because of their large surface-to-volume ratio, surface states in NWs can easily affect the metallic contacts to NWs and electron transport in NW. Here, we present ZnO NW surface analysis by performing current–voltage characterization on ZnO NW Schottky barrier field effect transistors with different metal contacts (Ti, Al, Au) at both room temperature and cryogenic temperature. Our results show that three metal contacts are all Schottky contacts to ZnO NWs due to surface states. Our further study reveals: (a) the surface states related Schottky barrier height (SBH) can be extracted from a back to back Schottky diodes model and the SBH values are in the range of 0.34–0.37 eV for three metal contacts; (b) the trap activation energy determined from the Arrhenius plots of different Schottky metal contacts is in the range of 0.23–0.29 eV, which is oxygen vacancies related; and (c) based on the space-charge-limited model, the surface state density of ZnO NW is in the range of 1.04 × 10 10 –1.24 × 10 10 /cm 2

High-gain subnanowatt power consumption hybrid complementary logic inverter with WSe2 nanosheet and ZnO nanowire transistors on glass.

Science.gov (United States)

Shokouh, Seyed Hossein Hosseini; Pezeshki, Atiye; Ali Raza, Syed Raza; Lee, Hee Sung; Min, Sung-Wook; Jeon, Pyo Jin; Shin, Jae Min; Im, Seongil

2015-01-07

A 1D-2D hybrid complementary logic inverter comprising of ZnO nanowire and WSe2 nanosheet field-effect transistors (FETs) is fabricated on glass, which shows excellent static and dynamic electrical performances with a voltage gain of ≈60, sub-nanowatt power consumption, and at least 1 kHz inverting speed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Near-thermal limit gating in heavily doped III-V semiconductor nanowires using polymer electrolytes

Science.gov (United States)

Ullah, A. R.; Carrad, D. J.; Krogstrup, P.; Nygârd, J.; Micolich, A. P.

2018-02-01

Doping is a common route to reducing nanowire transistor on-resistance but it has limits. A high doping level gives significant loss in gate performance and ultimately complete gate failure. We show that electrolyte gating remains effective even when the Be doping in our GaAs nanowires is so high that traditional metal-oxide gates fail. In this regime we obtain a combination of subthreshold swing and contact resistance that surpasses the best existing p -type nanowire metal-oxide semiconductor field-effect transistors (MOSFETs). Our subthreshold swing of 75 mV/dec is within 25 % of the room-temperature thermal limit and comparable with n -InP and n -GaAs nanowire MOSFETs. Our results open a new path to extending the performance and application of nanowire transistors, and motivate further work on improved solid electrolytes for nanoscale device applications.

New junctionless RADFET dosimeter design for low-cost radiation monitoring applications

International Nuclear Information System (INIS)

Arar, Djemai; Djeffal, Faycal; Bentrcia, Toufik; Chahdi, Mohamed

2014-01-01

This paper is devoted to the presentation of a quantitative analysis of the Junctionless Gate All Around RADFET (JL GAA RADFET) dosimeter, where the numerical simulation has been carried out using the Atlas 3-D simulator. The impact of the total dose, alternative gate materials and the channel doping on the threshold voltage of the JL GAA RADFET is addressed. The obtained results have indicated a significant improvement in the subthreshold parameters when compared to the conventional GAA RADFET dosimeter. Therefore, the implementation of junctionless-based sensors in the near future can provide more accurate results with low costs, in addition to alleviating many difficulties in the measurement procedure. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

New junctionless RADFET dosimeter design for low-cost radiation monitoring applications

Energy Technology Data Exchange (ETDEWEB)

Arar, Djemai; Djeffal, Faycal [Department of Electronics, University of Batna, Batna 05000 (Algeria); Bentrcia, Toufik; Chahdi, Mohamed [Department of Physics, University of Batna, Batna 05000 (Algeria)

2014-01-15

This paper is devoted to the presentation of a quantitative analysis of the Junctionless Gate All Around RADFET (JL GAA RADFET) dosimeter, where the numerical simulation has been carried out using the Atlas 3-D simulator. The impact of the total dose, alternative gate materials and the channel doping on the threshold voltage of the JL GAA RADFET is addressed. The obtained results have indicated a significant improvement in the subthreshold parameters when compared to the conventional GAA RADFET dosimeter. Therefore, the implementation of junctionless-based sensors in the near future can provide more accurate results with low costs, in addition to alleviating many difficulties in the measurement procedure. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

KAUST Repository

Caraveo-Frescas, J. A.; Alshareef, Husam N.

2013-01-01

p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p

Enhancement in the photodetection of ZnO nanowires by introducing surface-roughness-induced traps

International Nuclear Information System (INIS)

Park, Woojin; Jo, Gunho; Hong, Woong-Ki; Yoon, Jongwon; Choe, Minhyeok; Ji, Yongsung; Kim, Geunjin; Kahng, Yung Ho; Lee, Kwanghee; Lee, Takhee; Lee, Sangchul; Wang, Deli

2011-01-01

We investigated the enhanced photoresponse of ZnO nanowire transistors that was introduced with surface-roughness-induced traps by a simple chemical treatment with isopropyl alcohol (IPA). The enhanced photoresponse of IPA-treated ZnO nanowire devices is attributed to an increase in adsorbed oxygen on IPA-induced surface traps. The results of this study revealed that IPA-treated ZnO nanowire devices displayed higher photocurrent gains and faster photoswitching speed than transistors containing unmodified ZnO nanowires. Thus, chemical treatment with IPA can be a useful method for improving the photoresponse of ZnO nanowire devices.

High-performance ambipolar self-assembled Au/Ag nanowire based vertical quantum dot field effect transistor.

Science.gov (United States)

Song, Xiaoxian; Zhang, Yating; Zhang, Haiting; Yu, Yu; Cao, Mingxuan; Che, Yongli; Wang, Jianlong; Dai, Haitao; Yang, Junbo; Ding, Xin; Yao, Jianquan

2016-10-07

Most lateral PbSe quantum dot field effect transistors (QD FETs) show a low on current/off current (I on/I off) ratio in charge transport measurements. A new strategy to provide generally better performance is to design PbSe QD FETs with vertical architecture, in which the structure parameters can be tuned flexibly. Here, we fabricated a novel room-temperature operated vertical quantum dot field effect transistor with a channel of 580 nm, where self-assembled Au/Ag nanowires served as source transparent electrodes and PbSe quantum dots as active channels. Through investigating the electrical characterization, the ambipolar device exhibited excellent characteristics with a high I on/I off current ratio of about 1 × 10(5) and a low sub-threshold slope (0.26 V/decade) in the p-type regime. The all-solution processing vertical architecture provides a convenient way for low cost, large-area integration of the device.

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

DEFF Research Database (Denmark)

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

2017-01-01

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

A sub k{sub B}T/q semimetal nanowire field effect transistor

Energy Technology Data Exchange (ETDEWEB)

Ansari, L.; Fagas, G.; Gity, F.; Greer, J. C., E-mail: Jim.Greer@Tyndall.ie [Tyndall National Institute, Lee Maltings, Dyke Parade, Cork T12 R5CP (Ireland)

2016-08-08

The key challenge for nanoelectronics technologies is to identify the designs that work on molecular length scales, provide reduced power consumption relative to classical field effect transistors (FETs), and that can be readily integrated at low cost. To this end, a FET is introduced that relies on the quantum effects arising for semimetals patterned with critical dimensions below 5 nm, that intrinsically has lower power requirements due to its better than a “Boltzmann tyranny” limited subthreshold swing (SS) relative to classical field effect devices, eliminates the need to form heterojunctions, and mitigates against the requirement for abrupt doping profiles in the formation of nanowire tunnel FETs. This is achieved through using a nanowire comprised of a single semimetal material while providing the equivalent of a heterojunction structure based on shape engineering to avail of the quantum confinement induced semimetal-to-semiconductor transition. Ab initio calculations combined with a non-equilibrium Green's function formalism for charge transport reveals tunneling behavior in the OFF state and a resonant conduction mechanism for the ON state. A common limitation to tunnel FET (TFET) designs is related to a low current in the ON state. A discussion relating to the semimetal FET design to overcome this limitation while providing less than 60 meV/dec SS at room temperature is provided.

Si/Ge hetero-structure nanotube tunnel field effect transistor

KAUST Repository

Hanna, A. N.

2015-01-07

We discuss the physics of conventional channel material (silicon/germanium hetero-structure) based transistor topology mainly core/shell (inner/outer) gated nanotube vs. gate-all-around nanowire architecture for tunnel field effect transistor application. We show that nanotube topology can result in higher performance through higher normalized current when compared to nanowire architecture at Vdd-=-1-V due to the availability of larger tunneling cross section and lower Shockley-Reed-Hall recombination. Both architectures are able to achieve sub 60-mV/dec performance for more than five orders of magnitude of drain current. This enables the nanotube configuration achieving performance same as the nanowire architecture even when Vdd is scaled down to 0.5-V.

Si/Ge hetero-structure nanotube tunnel field effect transistor

KAUST Repository

Hanna, A. N.; Hussain, Muhammad Mustafa

2015-01-01

We discuss the physics of conventional channel material (silicon/germanium hetero-structure) based transistor topology mainly core/shell (inner/outer) gated nanotube vs. gate-all-around nanowire architecture for tunnel field effect transistor application. We show that nanotube topology can result in higher performance through higher normalized current when compared to nanowire architecture at Vdd-=-1-V due to the availability of larger tunneling cross section and lower Shockley-Reed-Hall recombination. Both architectures are able to achieve sub 60-mV/dec performance for more than five orders of magnitude of drain current. This enables the nanotube configuration achieving performance same as the nanowire architecture even when Vdd is scaled down to 0.5-V.

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.

Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors

Science.gov (United States)

Lei, Yanlian; Deng, Ping; Li, Jun; Lin, Ming; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Ong, Beng S.

2016-01-01

Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility. Conversely, the readily soluble, low-MW D-A polymers give low mobility. We report herein a facile solution process which transformed a lower-MW, low-mobility diketopyrrolopyrrole-dithienylthieno[3,2-b]thiophene (I) into a high crystalline order and high-mobility semiconductor for OFETs applications. The process involved solution fabrication of a channel semiconductor film from a lower-MW (I) and polystyrene blends. With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm2V−1s−1), on/off ratio (107), and other desirable field-effect properties that meet impactful OFET application requirements. PMID:27091315

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

Science.gov (United States)

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

2009-11-11

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

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

International Nuclear Information System (INIS)

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

2009-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2009-11-11

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

Observation of diameter dependent carrier distribution in nanowire-based transistors

Energy Technology Data Exchange (ETDEWEB)

Schulze, A; Hantschel, T; Eyben, P; Verhulst, A S; Rooyackers, R; Vandooren, A; Mody, J; Nazir, A; Leonelli, D; Vandervorst, W, E-mail: Andreas.Schulze@imec.be [IMEC, Kapeldreef 75, 3001 Leuven (Belgium)

2011-05-06

The successful implementation of nanowire (NW) based field-effect transistors (FET) critically depends on quantitative information about the carrier distribution inside such devices. Therefore, we have developed a method based on high-vacuum scanning spreading resistance microscopy (HV-SSRM) which allows two-dimensional (2D) quantitative carrier profiling of fully integrated silicon NW-based tunnel-FETs (TFETs) with 2 nm spatial resolution. The key elements of our characterization procedure are optimized NW cleaving and polishing steps, the use of in-house fabricated ultra-sharp diamond tips, measurements in high vacuum and a dedicated quantification procedure accounting for the Schottky-like tip-sample contact affected by surface states. In the case of the implanted TFET source regions we find a strong NW diameter dependence of conformality, junction abruptness and gate overlap, quantitatively in agreement with process simulations. In contrast, the arsenic doped drain regions reveal an unexpected NW diameter dependent dopant deactivation. The observed lower drain doping for smaller diameters is reflected in the device characteristics by lower TFET off-currents, as measured experimentally and confirmed by device simulations.

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

CERN Document Server

Wang, Zhong Lin

2010-01-01

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

A Water-Based Silver-Nanowire Screen-Print Ink for the Fabrication of Stretchable Conductors and Wearable Thin-Film Transistors.

Science.gov (United States)

Liang, Jiajie; Tong, Kwing; Pei, Qibing

2016-07-01

A water-based silver-nanowire (AgNW) ink is formulated for screen printing. Screen-printed AgNW patterns have uniform sharp edges, ≈50 μm resolution, and electrical conductivity as high as 4.67 × 10(4) S cm(-1) . The screen-printed AgNW patterns are used to fabricate a stretchable composite conductor, and a fully printed and intrinsically stretchable thin-film transistor array is also realized. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Label Free Detection of Biomolecules Using Charge-Plasma-Based Gate Underlap Dielectric Modulated Junctionless TFET

Science.gov (United States)

Wadhwa, Girish; Raj, Balwinder

2018-05-01

Nanoscale devices are emerging as a platform for detecting biomolecules. Various issues were observed during the fabrication process such as random dopant fluctuation and thermal budget. To reduce these issues charge-plasma-based concept is introduced. This paper proposes the implementation of charge-plasma-based gate underlap dielectric modulated junctionless tunnel field effect transistor (DM-JLTFET) for the revelation of biomolecule immobilized in the open cavity gate channel region. In this p+ source and n+ drain regions are introduced by employing different work function over the intrinsic silicon. Also dual material gate architecture is implemented to reduce short channel effect without abandoning any other device characteristic. The sensitivity of biosensor is studied for both the neutral and charge-neutral biomolecules. The effect of device parameters such as channel thickness, cavity length and cavity thickness on drain current have been analyzed through simulations. This paper investigates the performance of charge-plasma-based gate underlap DM-JLTFET for biomolecule sensing applications while varying dielectric constant, charge density at different biasing conditions.

Screening model for nanowire surface-charge sensors in liquid

DEFF Research Database (Denmark)

Sørensen, Martin Hedegård; Mortensen, Asger; Brandbyge, Mads

2007-01-01

The conductance change of nanowire field-effect transistors is considered a highly sensitive probe for surface charge. However, Debye screening of relevant physiological liquid environments challenge device performance due to competing screening from the ionic liquid and nanowire charge carriers....

Realization of size controllable graphene micro/nanogap with a micro/nanowire mask method for organic field-effect transistors

DEFF Research Database (Denmark)

Liao, Zhiyu; Wan, Qing; Liu, Huixuan

2011-01-01

with the graphene micro/nanogap bottom electrodes. The ultrathin thickness of the graphene, combined with its good compatibility with organic semiconductors, and high electrical conductivity produced high-performance CuPc film device with mobility at 0.053 cm(2)/Vs and on/off ratio at 10(5), showing promising......A size controllable graphene micro/nanogap fabrication method using micro/nanowire as mask is presented. The gap dimension can be adjusted by the diameter of the mask wire. As a typical application, copper phthalocyanine (CuPc) film organic field-effect transistors (OFETs) were fabricated...

Performance analysis and simulation of vertical gallium nitride nanowire transistors

Science.gov (United States)

Witzigmann, Bernd; Yu, Feng; Frank, Kristian; Strempel, Klaas; Fatahilah, Muhammad Fahlesa; Schumacher, Hans Werner; Wasisto, Hutomo Suryo; Römer, Friedhard; Waag, Andreas

2018-06-01

Gallium nitride (GaN) nanowire transistors are analyzed using hydrodynamic simulation. Both p-body and n-body devices are compared in terms of threshold voltage, saturation behavior and transconductance. The calculations are calibrated using experimental data. The threshold voltage can be tuned from enhancement to depletion mode with wire doping. Surface states cause a shift of threshold voltage and saturation current. The saturation current depends on the gate design, with a composite gate acting as field plate in the p-body device. He joined Bell Laboratories, Murray Hill, NJ, as a Technical Staff Member. In October 2001, he joined the Optical Access and Transport Division, Agere Systems, Alhambra, CA. In 2004, he was appointed an Assistant Professor at ETH Zurich,. Since 2008, at the University of Kassel, Kassel, Germany, and he has been a Professor the Head of the Computational Electronics and Photonics Group, and co-director of CINSaT since 2010. His research interests include computational optoelectronics, process and device design of semiconductor photonic devices, microwave components, and electromagnetics modeling for nanophotonics. Dr. Witzigmann is a senior member of the SPIE and IEEE.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

A simulation-based proposed high-k heterostructure AlGaAs/Si junctionless n-type tunnel FET

International Nuclear Information System (INIS)

Rahi Shiromani Balmukund; Asthana Pranav; Ghosh Bahniman

2014-01-01

We propose a heterostructure junctionless tunnel field effect transistor (HJL-TFET) using AlGaAs/Si. In the proposed HJL-TFET, low band gap silicon is used in the source side and higher band gap AlGaAs in the drain side. The whole AlGaAs/Si region is heavily doped n-type. The proposed HJL-TFET uses two isolated gates (named gate, gate1) with two different work functions (gate = 4.2 eV, gate1 = 5.2 eV respectively). The 2-D nature of HJL-TFET current flow is studied. The proposed structure is simulated in Silvaco with different gate dielectric materials. This structure exhibits a high on current in the range of 1.4 × 10 −6 A/μm, the off current remains as low as 9.1 × 10 −14 A/μm. So I ON /I OFF ratio of ≃ 10 8 is achieved. Point subthreshold swing has also been reduced to a value of ≃ 41 mV/decade for TiO 2 gate material. (semiconductor devices)

Junction-less poly-Ge FinFET and charge-trap NVM fabricated by laser-enabled low thermal budget processes

Energy Technology Data Exchange (ETDEWEB)

Huang, Wen-Hsien; Shen, Chang-Hong; Wang, Hsing-Hsiang; Yang, Chih-Chao; Hsieh, Tung-Ying; Hsieh, Jin-Long; Yeh, Wen-Kuan [National Nano Device Laboratories, No. 26, Prosperity Road 1, Hsinchu 30078, Taiwan (China); Shieh, Jia-Min, E-mail: jmshieh@narlabs.org.tw, E-mail: jmshieh@faculty.nctu.edu.tw [National Nano Device Laboratories, No. 26, Prosperity Road 1, Hsinchu 30078, Taiwan (China); Departments of Photonics and Institute of Electro-Optical Engineering, National Chiao-Tung University, Hsinchu 30010, Taiwan (China); Huang, Tzu-En [Departments of Photonics and Institute of Electro-Optical Engineering, National Chiao-Tung University, Hsinchu 30010, Taiwan (China)

2016-06-13

A doping-free poly-Ge film as channel material was implemented by CVD-deposited nano-crystalline Ge and visible-light laser crystallization, which behaves as a p-type semiconductor, exhibiting holes concentration of 1.8 × 10{sup 18 }cm{sup −3} and high crystallinity (Raman FWHM ∼ 4.54 cm{sup −1}). The fabricated junctionless 7 nm-poly-Ge FinFET performs at an I{sub on}/I{sub off} ratio over 10{sup 5} and drain-induced barrier lowering of 168 mV/V. Moreover, the fast programming speed of 100 μs–1 ms and reliable retention can be obtained from the junctionless poly-Ge nonvolatile-memory. Such junctionless poly-Ge devices with low thermal budget are compatible with the conventional CMOS technology and are favorable for 3D sequential-layer integration and flexible electronics.

Charge pumping in InAs nanowires by surface acoustic waves

NARCIS (Netherlands)

Roddaro, Stefano; Strambini, Elia; Romeo, Lorenzo; Piazza, Vincenzo; Nilsson, Kristian; Samuelson, Lars; Beltram, Fabio

2010-01-01

We investigate the interaction between surface acoustic waves on a piezoelectric LiNbO3 substrate and charge carriers in InAs nanowire transistors. Interdigital transducers are used to excite electromechanical waves on the chip surface and their influence on the transport in the nanowire devices is

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.

Recent progress in photoactive organic field-effect transistors.

Science.gov (United States)

Wakayama, Yutaka; Hayakawa, Ryoma; Seo, Hoon-Seok

2014-04-01

Recent progress in photoactive organic field-effect transistors (OFETs) is reviewed. Photoactive OFETs are divided into light-emitting (LE) and light-receiving (LR) OFETs. In the first part, LE-OFETs are reviewed from the viewpoint of the evolution of device structures. Device performances have improved in the last decade with the evolution of device structures from single-layer unipolar to multi-layer ambipolar transistors. In the second part, various kinds of LR-OFETs are featured. These are categorized according to their functionalities: phototransistors, non-volatile optical memories, and photochromism-based transistors. For both, various device configurations are introduced: thin-film based transistors for practical applications, single-crystalline transistors to investigate fundamental physics, nanowires, multi-layers, and vertical transistors based on new concepts.

Recent progress in photoactive organic field-effect transistors

International Nuclear Information System (INIS)

Wakayama, Yutaka; Hayakawa, Ryoma; Seo, Hoon-Seok

2014-01-01

Recent progress in photoactive organic field-effect transistors (OFETs) is reviewed. Photoactive OFETs are divided into light-emitting (LE) and light-receiving (LR) OFETs. In the first part, LE-OFETs are reviewed from the viewpoint of the evolution of device structures. Device performances have improved in the last decade with the evolution of device structures from single-layer unipolar to multi-layer ambipolar transistors. In the second part, various kinds of LR-OFETs are featured. These are categorized according to their functionalities: phototransistors, non-volatile optical memories, and photochromism-based transistors. For both, various device configurations are introduced: thin-film based transistors for practical applications, single-crystalline transistors to investigate fundamental physics, nanowires, multi-layers, and vertical transistors based on new concepts. (review)

Direct-write fabrication of a nanoscale digital logic element on a single nanowire

International Nuclear Information System (INIS)

Roy, Somenath; Gao Zhiqiang

2010-01-01

In this paper we report on the 'direct-write' fabrication and electrical characteristics of a nanoscale logic inverter, integrating enhancement-mode (E-mode) and depletion-mode (D-mode) field-effect transistors (FETs) on a single zinc oxide (ZnO) nanowire. 'Direct-writing' of platinum metal electrodes and a dielectric layer is executed on individual single-crystalline ZnO nanowires using either a focused electron beam (FEB) or a focused ion beam (FIB). We fabricate a top-gate FET structure, in which the gate electrode wraps around the ZnO nanowire, resulting in a more efficient gate response than the conventional back-gate nanowire transistors. For E-mode device operation, the gate electrode (platinum) is deposited directly onto the ZnO nanowire by a FEB, which creates a Schottky barrier and in turn a fully depleted channel. Conversely, sandwiching an insulating layer between the FIB-deposited gate electrode and the nanowire channel makes D-mode operation possible. Integrated E- and D-mode FETs on a single nanowire exhibit the characteristics of a direct-coupled FET logic (DCFL) inverter with a high gain and noise margin.

Gate engineered heterostructure junctionless TFET with Gaussian doping profile for ambipolar suppression and electrical performance improvement

Science.gov (United States)

Aghandeh, Hadi; Sedigh Ziabari, Seyed Ali

2017-11-01

This study investigates a junctionless tunnel field-effect transistor with a dual material gate and a heterostructure channel/source interface (DMG-H-JLTFET). We find that using the heterostructure interface improves device behavior by reducing the tunneling barrier width at the channel/source interface. Simultaneously, the dual material gate structure decreases ambipolar current by increasing the tunneling barrier width at the drain/channel interface. The performance of the device is analyzed based on the energy band diagram at on, off, and ambipolar states. Numerical simulations demonstrate improvements in ION, IOFF, ION/IOFF, subthreshold slope (SS), transconductance and cut-off frequency and suppressed ambipolar behavior. Next, the workfunction optimization of dual material gate is studied. It is found that if appropriate workfunctions are selected for tunnel and auxiliary gates, the JLTFET exhibits considerably improved performance. We then study the influence of Gaussian doping distribution at the drain and the channel on the ambipolar performance of the device and find that a Gaussian doping profile and a dual material gate structure remarkably reduce ambipolar current. Gaussian doped DMG-H-JLTFET, also exhibits enhanced IOFF, ION/IOFF, SS and a low threshold voltage without degrading IOFF.

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.

Influence of surface charge on the transport characteristics of nanowire-field effect transistors in liquid environments

Energy Technology Data Exchange (ETDEWEB)

Nozaki, Daijiro, E-mail: daijiro.nozaki@gmail.com, E-mail: research@nano.tu-dresden.de [Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, 01062 Dresden (Germany); Kunstmann, Jens [Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, 01062 Dresden (Germany); Theoretical Chemistry, Department of Chemistry and Food Chemistry, TU Dresden, 01062 Dresden (Germany); Zörgiebel, Felix [Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, 01062 Dresden (Germany); Center for Advancing Electronics Dresden (cfAED), TU Dresden, 01062 Dresden (Germany); Cuniberti, Gianaurelio [Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, 01062 Dresden (Germany); Center for Advancing Electronics Dresden (cfAED), TU Dresden, 01062 Dresden (Germany); Dresden Center for Computational Materials Science (DCCMS), TU Dresden, 01062 Dresden (Germany)

2015-05-18

One dimensional nanowire field effect transistors (NW-FETs) are a promising platform for sensor applications. The transport characteristics of NW-FETs are strongly modified in liquid environment due to the charging of surface functional groups accompanied with protonation or deprotonation. In order to investigate the influence of surface charges and ionic concentrations on the transport characteristics of Schottky-barrier NW-FETs, we have combined the modified Poisson-Boltzmann theory with the Landauer-Büttiker transport formalism. For a typical device, the model is able to capture the reduction of the sensitivity of NW-FETs in ionic solutions due to the screening from counter ions as well as a local gating from surface functional groups. Our approach allows to model, to investigate, and to optimize realistic Schottky-barrier NW-FET devices in liquid environment.

High mobility ZnO nanowires for terahertz detection applications

International Nuclear Information System (INIS)

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

2014-01-01

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

Detection of chemical substances in water using an oxide nanowire transistor covered with a hydrophobic nanoparticle thin film as a liquid-vapour separation filter

Directory of Open Access Journals (Sweden)

Taekyung Lim

2016-08-01

Full Text Available We have developed a method to detect the presence of small amounts of chemical substances in water, using a Al2O3 nanoparticle thin film covered with phosphonic acid (HDF-PA self-assembled monolayer. The HDF-PA self-assembled Al2O3 nanoparticle thin film acts as a liquid-vapour separation filter, allowing the passage of chemical vapour while blocking liquids. Prevention of the liquid from contacting the SnO2 nanowire and source-drain electrodes is required in order to avoid abnormal operation. Using this characteristic, the concentration of chemical substances in water could be evaluated by measuring the current changes in the SnO2 nanowire transistor covered with the HDF-PA self-assembled Al2O3 nanoparticle thin film.

Non-classical logic inverter coupling a ZnO nanowire-based Schottky barrier transistor and adjacent Schottky diode.

Science.gov (United States)

Hosseini Shokouh, Seyed Hossein; Raza, Syed Raza Ali; Lee, Hee Sung; Im, Seongil

2014-08-21

On a single ZnO nanowire (NW), we fabricated an inverter-type device comprising a Schottky diode (SD) and field-effect transistor (FET), aiming at 1-dimensional (1D) electronic circuits with low power consumption. The SD and adjacent FET worked respectively as the load and driver, so that voltage signals could be easily extracted as the output. In addition, NW FET with a transparent conducting oxide as top gate turned out to be very photosensitive, although ZnO NW SD was blind to visible light. Based on this, we could achieve an array of photo-inverter cells on one NW. Our non-classical inverter is regarded as quite practical for both logic and photo-sensing due to its performance as well as simple device configuration.

SnO2Nanowire Arrays and Electrical Properties Synthesized by Fast Heating a Mixture of SnO2and CNTs Waste Soot

Directory of Open Access Journals (Sweden)

Zhou Zhi-Hua

2009-01-01

Full Text Available Abstract SnO2nanowire arrays were synthesized by fast heating a mixture of SnO2and the carbon nanotubes waste soot by high-frequency induction heating. The resultant SnO2nanowires possess diameters from 50 to 100 nm and lengths up to tens of mircrometers. The field-effect transistors based on single SnO2nanowire exhibit that as-synthesized nanowires have better transistor performance in terms of transconductance and on/off ratio. This work demonstrates a simple technique to the growth of nanomaterials for application in future nanoelectronic devices.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

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

Science.gov (United States)

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

2011-10-07

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

Enhancing Photoresponsivity of Self-Aligned MoS2 Field-Effect Transistors by Piezo-Phototronic Effect from GaN Nanowires.

Science.gov (United States)

Liu, Xingqiang; Yang, Xiaonian; Gao, Guoyun; Yang, Zhenyu; Liu, Haitao; Li, Qiang; Lou, Zheng; Shen, Guozhen; Liao, Lei; Pan, Caofeng; Lin Wang, Zhong

2016-08-23

We report high-performance self-aligned MoS2 field-effect transistors (FETs) with enhanced photoresponsivity by the piezo-phototronic effect. The FETs are fabricated based on monolayer MoS2 with a piezoelectric GaN nanowire (NW) as the local gate, and a self-aligned process is employed to define the source/drain electrodes. The fabrication method allows the preservation of the intrinsic property of MoS2 and suppresses the scattering center density in the MoS2/GaN interface, which results in high electrical and photoelectric performances. MoS2 FETs with channel lengths of ∼200 nm have been fabricated with a small subthreshold slope of 64 mV/dec. The photoresponsivity is 443.3 A·W(-1), with a fast response and recovery time of ∼5 ms under 550 nm light illumination. When strain is introduced into the GaN NW, the photoresponsivity is further enhanced to 734.5 A·W(-1) and maintains consistent response and recovery time, which is comparable with that of the mechanical exfoliation of MoS2 transistors. The approach presented here opens an avenue to high-performance top-gated piezo-enhanced MoS2 photodetectors.

Electrical and Optical Characterization of Nanowire based Semiconductor Devices

Science.gov (United States)

Ayvazian, Talin

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

High performance non-volatile ferroelectric copolymer memory based on a ZnO nanowire transistor fabricated on a transparent substrate

International Nuclear Information System (INIS)

Nedic, Stanko; Welland, Mark; Tea Chun, Young; Chu, Daping; Hong, Woong-Ki

2014-01-01

A high performance ferroelectric non-volatile memory device based on a top-gate ZnO nanowire (NW) transistor fabricated on a glass substrate is demonstrated. The ZnO NW channel was spin-coated with a poly (vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) layer acting as a top-gate dielectric without buffer layer. Electrical conductance modulation and memory hysteresis are achieved by a gate electric field induced reversible electrical polarization switching of the P(VDF-TrFE) thin film. Furthermore, the fabricated device exhibits a memory window of ∼16.5 V, a high drain current on/off ratio of ∼10 5 , a gate leakage current below ∼300 pA, and excellent retention characteristics for over 10 4 s

Failure mechanisms and electromechanical coupling in semiconducting nanowires

Directory of Open Access Journals (Sweden)

Peng B.

2010-06-01

Full Text Available One dimensional nanostructures, like nanowires and nanotubes, are increasingly being researched for the development of next generation devices like logic gates, transistors, and solar cells. In particular, semiconducting nanowires with a nonsymmetric wurtzitic crystal structure, such as zinc oxide (ZnO and gallium nitride (GaN, have drawn immense research interests due to their electromechanical coupling. The designing of the future nanowire-based devices requires component-level characterization of individual nanowires. In this paper, we present a unique experimental set-up to characterize the mechanical and electromechanical behaviour of individual nanowires. Using this set-up and complementary atomistic simulations, mechanical properties of ZnO nanowires and electromechanical properties of GaN nanowires were investigated. In ZnO nanowires, elastic modulus was found to depend on nanowire diameter decreasing from 190 GPa to 140 GPa as the wire diameter increased from 5 nm to 80 nm. Inconsistent failure mechanisms were observed in ZnO nanowires. Experiments revealed a brittle fracture, whereas simulations using a pairwise potential predicted a phase transformation prior to failure. This inconsistency is addressed in detail from an experimental as well as computational perspective. Lastly, in addition to mechanical properties, preliminary results on the electromechanical properties of gallium nitride nanowires are also reported. Initial investigations reveal that the piezoresistive and piezoelectric behaviour of nanowires is different from bulk gallium nitride.

Reactive diffusion and stresses in nanowires or nanorods

International Nuclear Information System (INIS)

Roussel, Manuel; Erdélyi, Zoltán; Schmitz, Guido

2017-01-01

Heterostructured nanowires are of prime interest in nowadays technology such as field-effect transistors, field emitters, batteries and solar cells. We consider their aging behavior and developed a model focusing on reactive diffusion in core-shell nanowires. A complete set of analytical equations is presented that takes into account thermodynamic driving forces, vacancy distribution, elastic stress and its plastic relaxation. This complete description of the reactive diffusion can be used in finite element simulations to investigate diffusion processes in various geometries. In order to show clearly the interplay between the cylindrical geometry, the reactive diffusion and the stresses developing in the nanowire, we investigate the formation of an intermetallic reaction product in various core-shell geometries. Emphasis is placed on showing how it is possible to control the kinetics of the reaction by applying an axial stress to the nanowires.

Tuning electronic properties of In2O3 nanowires by doping control

International Nuclear Information System (INIS)

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

2004-01-01

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

Surface roughness induced electron mobility degradation in InAs nanowires

International Nuclear Information System (INIS)

Wang Fengyun; Yip, Sen Po; Han, Ning; Fok, KitWa; Lin, Hao; Hou, Jared J; Dong, Guofa; Hung, Tak Fu; Chan, K S; Ho, Johnny C

2013-01-01

In this work, we present a study of the surface roughness dependent electron mobility in InAs nanowires grown by the nickel-catalyzed chemical vapor deposition method. These nanowires have good crystallinity, well-controlled surface morphology without any surface coating or tapering and an excellent peak field-effect mobility up to 15 000 cm 2 V −1 s −1 when configured into back-gated field-effect nanowire transistors. Detailed electrical characterizations reveal that the electron mobility degrades monotonically with increasing surface roughness and diameter scaling, while low-temperature measurements further decouple the effects of surface/interface traps and phonon scattering, highlighting the dominant impact of surface roughness scattering on the electron mobility for miniaturized and surface disordered nanowires. All these factors suggest that careful consideration of nanowire geometries and surface condition is required for designing devices with optimal performance. (paper)

Silicon nanowire arrays as learning chemical vapour classifiers

International Nuclear Information System (INIS)

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

2011-01-01

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

Quantifying signal changes in nano-wire based biosensors

DEFF Research Database (Denmark)

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

2011-01-01

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

Effect of liquid gate bias rising time in pH sensors based on Si nanowire ion sensitive field effect transistors

Science.gov (United States)

Jang, Jungkyu; Choi, Sungju; Kim, Jungmok; Park, Tae Jung; Park, Byung-Gook; Kim, Dong Myong; Choi, Sung-Jin; Lee, Seung Min; Kim, Dae Hwan; Mo, Hyun-Sun

2018-02-01

In this study, we investigate the effect of rising time (TR) of liquid gate bias (VLG) on transient responses in pH sensors based on Si nanowire ion-sensitive field-effect transistors (ISFETs). As TR becomes shorter and pH values decrease, the ISFET current takes a longer time to saturate to the pH-dependent steady-state value. By correlating VLG with the internal gate-to-source voltage of the ISFET, we found that this effect occurs when the drift/diffusion of mobile ions in analytes in response to VLG is delayed. This gives us useful insight on the design of ISFET-based point-of-care circuits and systems, particularly with respect to determining an appropriate rising time for the liquid gate bias.

Controllable electrical properties of metal-doped In2O3 nanowires for high-performance enhancement-mode transistors.

Science.gov (United States)

Zou, Xuming; Liu, Xingqiang; Wang, Chunlan; Jiang, Ying; Wang, Yong; Xiao, Xiangheng; Ho, Johnny C; Li, Jinchai; Jiang, Changzhong; Xiong, Qihua; Liao, Lei

2013-01-22

In recent years, In(2)O(3) nanowires (NWs) have been widely explored in many technological areas due to their excellent electrical and optical properties; however, most of these devices are based on In(2)O(3) NW field-effect transistors (FETs) operating in the depletion mode, which induces relatively higher power consumption and fancier circuit integration design. Here, n-type enhancement-mode In(2)O(3) NW FETs are successfully fabricated by doping different metal elements (Mg, Al, and Ga) in the NW channels. Importantly, the resulting threshold voltage can be effectively modulated through varying the metal (Mg, Ga, and Al) content in the NWs. A series of scaling effects in the mobility, transconductance, threshold voltage, and source-drain current with respect to the device channel length are also observed. Specifically, a small gate delay time (0.01 ns) and high on-current density (0.9 mA/μm) are obtained at 300 nm channel length. Furthermore, Mg-doped In(2)O(3) NWs are then employed to fabricate NW parallel array FETs with a high saturation current (0.5 mA), on/off ratio (>10(9)), and field-effect mobility (110 cm(2)/V·s), while the subthreshold slope and threshold voltage do not show any significant changes. All of these results indicate the great potency for metal-doped In(2)O(3) NWs used in the low-power, high-performance thin-film transistors.

Guided Growth of Horizontal p-Type ZnTe Nanowires

Science.gov (United States)

2016-01-01

A major challenge toward large-scale integration of nanowires is the control over their alignment and position. A possible solution to this challenge is the guided growth process, which enables the synthesis of well-aligned horizontal nanowires that grow according to specific epitaxial or graphoepitaxial relations with the substrate. However, the guided growth of horizontal nanowires was demonstrated for a limited number of materials, most of which exhibit unintentional n-type behavior. Here we demonstrate the vapor–liquid–solid growth of guided horizontal ZnTe nanowires and nanowalls displaying p-type behavior on four different planes of sapphire. The growth directions of the nanowires are determined by epitaxial relations between the nanowires and the substrate or by a graphoepitaxial effect that guides their growth along nanogrooves or nanosteps along the surface. We characterized the crystallographic orientations and elemental composition of the nanowires using transmission electron microscopy and photoluminescence. The optoelectronic and electronic properties of the nanowires were studied by fabricating photodetectors and top-gate thin film transistors. These measurements showed that the guided ZnTe nanowires are p-type semiconductors and are photoconductive in the visible range. The guided growth of horizontal p-type nanowires opens up the possibility of parallel nanowire integration into functional systems with a variety of potential applications not available by other means. PMID:27885331

Ultralow power complementary inverter circuits using axially doped p- and n-channel Si nanowire field effect transistors.

Science.gov (United States)

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

2016-06-09

We have successfully synthesized axially doped p- and n-type regions on a single Si nanowire (NW). Diodes and complementary metal-oxide-semiconductor (CMOS) inverter devices using single axial p- and n-channel Si NW field-effect transistors (FETs) were fabricated. We show that the threshold voltages of both p- and n-channel Si NW FETs can be lowered to nearly zero by effectively controlling the doping concentration. Because of the high performance of the p- and n-type Si NW channel FETs, especially with regard to the low threshold voltage, the fabricated NW CMOS inverters have a low operating voltage (<3 V) while maintaining a high voltage gain (∼6) and ultralow static power dissipation (≤0.3 pW) at an input voltage of ±3 V. This result offers a viable way for the fabrication of a high-performance high-density logic circuit using a low-temperature fabrication process, which makes it suitable for flexible electronics.

Investigation of enhancement-mode AlGaN/GaN nanowire channel high-electron-mobility transistor with oxygen-containing plasma treatment

Science.gov (United States)

He, Yunlong; Wang, Chong; Mi, Minhan; Zhang, Meng; Zhu, Qing; Zhang, Peng; Wu, Ji; Zhang, Hengshuang; Zheng, Xuefeng; Yang, Ling; Duan, Xiaoling; Ma, Xiaohua; Hao, Yue

2017-05-01

A novel enhancement-mode (E-mode) AlGaN/GaN high-electron-mobility transistor (HEMT) has been fabricated, by combining nanowire channel (NC) structure fabrication and N2O (or O2) plasma treatment. A comparison of two NC-HEMTs with different plasma treatments has been made. The NC-HEMT with N2O plasma treatment shows an output current of 610 mA/mm and a peak transconductance of 450 mS/mm. The DIBL of the NC-HEMT with N2O plasma treatment is as low as 2 mV/V, and an SS of 70 mV/decade is achieved. The device exhibits an intrinsic current gain cutoff frequency f T of 19 GHz and a maximum oscillation frequency f max of 58 GHz.

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.

Improved sensing characteristics of dual-gate transistor sensor using silicon nanowire arrays defined by nanoimprint lithography

Science.gov (United States)

Lim, Cheol-Min; Lee, In-Kyu; Lee, Ki Joong; Oh, Young Kyoung; Shin, Yong-Beom; Cho, Won-Ju

2017-12-01

This work describes the construction of a sensitive, stable, and label-free sensor based on a dual-gate field-effect transistor (DG FET), in which uniformly distributed and size-controlled silicon nanowire (SiNW) arrays by nanoimprint lithography act as conductor channels. Compared to previous DG FETs with a planar-type silicon channel layer, the constructed SiNW DG FETs exhibited superior electrical properties including a higher capacitive-coupling ratio of 18.0 and a lower off-state leakage current under high-temperature stress. In addition, while the conventional planar single-gate (SG) FET- and planar DG FET-based pH sensors showed the sensitivities of 56.7 mV/pH and 439.3 mV/pH, respectively, the SiNW DG FET-based pH sensors showed not only a higher sensitivity of 984.1 mV/pH, but also a lower drift rate of 0.8% for pH-sensitivity. This demonstrates that the SiNW DG FETs simultaneously achieve high sensitivity and stability, with significant potential for future biosensing applications.

Comprehensive analysis of sub-20 nm black phosphorus based junctionless-recessed channel MOSFET for analog/RF applications

Science.gov (United States)

Kumar, Ajay; Tripathi, M. M.; Chaujar, Rishu

2018-04-01

In this work, a comprehensive analog and RF performance of a novel Black Phosphorus-Junctionless-Recessed Channel (BP-JL-RC) MOSFET has been explored at 45 nm technology node (Gate length = 20 nm). The integration of black phosphorus with junctionless recessed channel MOSFET, leads to higher drain current of about 0.3 mA and excellent switching ratio (of the order of 1011) due to reduced off-current which leads to improvement in sub-threshold slope (SS) (67mV/dec). Further, RF performance metrics have also been studied with an aim to analyze high-frequency performance. The following FOMs have been evaluated: cut-off frequency (fT), maximum oscillator frequency (fMAX), stern stability factor, various power gains and parasitic capacitances at THz frequency range. Thus, in addition to the high packing density offered by RC MOSFET, the proposed design finds numerous application at THz frequency making it a promising candidate at wafer scale integration level.

Analytical modeling of split-gate junction-less transistor for a biosensor application

Directory of Open Access Journals (Sweden)

Shradhya Singh

2018-04-01

Full Text Available This paper represents the analytical modeling of split-gate Dielectric Modulated Junction Less Transistor (JLT for label free electrical detection of bio molecules. Some part of the channel region is opened for providing the binding sites for the bio molecules unlike conventional MOSFET which is enclosed with the gate electrode. Due to this open area, the surface potential of this region affected by the charged and neutral bio molecules immobilized to the open region of channel. Surface potential of the channel region obtained by solving two-Dimensional Poisson's equation by potential profile having parabolic nature through channel region using technique called conformal mapping. By deriving the surface potential model, derivation of threshold model can also be done. For the detection of bio molecule, variation in to the threshold voltage due to binding of bio molecule in the gate underlap region is the sensing metric.

Nanowire NMOS Logic Inverter Characterization.

Science.gov (United States)

Hashim, Yasir

2016-06-01

This study is the first to demonstrate characteristics optimization of nanowire N-Channel Metal Oxide Semiconductor (NW-MOS) logic inverter. Noise margins and inflection voltage of transfer characteristics are used as limiting factors in this optimization. A computer-based model used to produce static characteristics of NW-NMOS logic inverter. In this research two circuit configuration of NW-NMOS inverter was studied, in first NW-NMOS circuit, the noise margin for (low input-high output) condition was very low. For second NMOS circuit gives excellent noise margins, and results indicate that optimization depends on applied voltage to the inverter. Increasing gate to source voltage with (2/1) nanowires ratio results better noise margins. Increasing of applied DC load transistor voltage tends to increasing in decreasing noise margins; decreasing this voltage will improve noise margins significantly.

Mapping the Coulomb Environment in Interference-Quenched Ballistic Nanowires.

Science.gov (United States)

Gutstein, D; Lynall, D; Nair, S V; Savelyev, I; Blumin, M; Ercolani, D; Ruda, H E

2018-01-10

The conductance of semiconductor nanowires is strongly dependent on their electrostatic history because of the overwhelming influence of charged surface and interface states on electron confinement and scattering. We show that InAs nanowire field-effect transistor devices can be conditioned to suppress resonances that obscure quantized conduction thereby revealing as many as six sub-bands in the conductance spectra as the Fermi-level is swept across the sub-band energies. The energy level spectra extracted from conductance, coupled with detailed modeling shows the significance of the interface state charge distribution revealing the Coulomb landscape of the nanowire device. Inclusion of self-consistent Coulomb potentials, the measured geometrical shape of the nanowire, the gate geometry and nonparabolicity of the conduction band provide a quantitative and accurate description of the confinement potential and resulting energy level structure. Surfaces of the nanowire terminated by HfO 2 are shown to have their interface donor density reduced by a factor of 30 signifying the passivating role played by HfO 2 .

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

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-aminopropyl)triethoxysilane (APTES) have demonstrated...

Tunneling and Transport in Nanowires

International Nuclear Information System (INIS)

Goldman, Allen M.

2016-01-01

The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO_3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

Gate-tunable transport characteristics of Bi2S3 nanowire transistors

Science.gov (United States)

Kilcoyne, Colin; Ali, Ahmed H.; Alsaqqa, Ali M.; Rahman, Ajara A.; Whittaker-Brooks, Luisa; Sambandamurthy, Ganapathy

2018-02-01

Electrical transport and resistance noise spectroscopy measurements are performed on individual, single crystalline Bi2S3 nanowires in the field-effect geometry. The nanowires exhibit n-type conduction and device characteristics such as activation energy, ON/OFF ratio, and mobility are calculated over a temperature range of 120-320 K and at several bias values. The noise magnitude is measured between 0.01 and 5 Hz at several gate voltages as the device turns from it's OFF to ON state. The presence of mid-gap states which act as charge traps within the band gap can potentially explain the observed transport characteristics. Sulfur vacancies are the likely origin of these mid-gap states which makes Bi2S3 nanowires appealing for defect engineering as a means to enhance its optoelectronic properties and also to better understand the important role of defects in nanoscale semiconductors.

Size-effects in indium gallium arsenide nanowire field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Zota, Cezar B., E-mail: cezar.zota@eit.lth.se; Lind, E. [Department of Electrical and Information Technology, Lund University, Lund 22101 (Sweden)

2016-08-08

We fabricate and analyze InGaAs nanowire MOSFETs with channel widths down to 18 nm. Low-temperature measurements reveal quantized conductance due to subband splitting, a characteristic of 1D systems. We relate these features to device performance at room-temperature. In particular, the threshold voltage versus nanowire width is explained by direct observation of quantization of the first sub-band, i.e., band gap widening. An analytical effective mass quantum well model is able to describe the observed band structure. The results reveal a compromise between reliability, i.e., V{sub T} variability, and on-current, through the mean free path, in the choice of the channel material.

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

Science.gov (United States)

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

2018-05-01

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

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.

Large-area fabrication of patterned ZnO-nanowire arrays using light stamping lithography.

Science.gov (United States)

Hwang, Jae K; Cho, Sangho; Seo, Eun K; Myoung, Jae M; Sung, Myung M

2009-12-01

We demonstrate selective adsorption and alignment of ZnO nanowires on patterned poly(dimethylsiloxane) (PDMS) thin layers with (aminopropyl)siloxane self-assembled monolayers (SAMs). Light stamping lithography (LSL) was used to prepare patterned PDMS thin layers as neutral passivation regions on Si substrates. (3-Aminopropyl)triethoxysilane-based SAMs were selectively formed only on regions exposing the silanol groups of the Si substrates. The patterned positively charged amino groups define and direct the selective adsorption of ZnO nanowires with negative surface charges in the protic solvent. This procedure can be adopted in automated printing machines that generate patterned ZnO-nanowire arrays on large-area substrates. To demonstrate its usefulness, the LSL method was applied to prepare ZnO-nanowire transistor arrays on 4-in. Si wafers.

Memory and learning behaviors mimicked in nanogranular SiO2-based proton conductor gated oxide-based synaptic transistors.

Science.gov (United States)

Wan, Chang Jin; Zhu, Li Qiang; Zhou, Ju Mei; Shi, Yi; Wan, Qing

2013-11-07

In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements.

Wurtzite InP nanowire arrays grown by selective area MOCVD

International Nuclear Information System (INIS)

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

2010-01-01

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

Simultaneous Detection of α-Fetoprotein and Carcinoembryonic Antigen Based on Si Nanowire Field-Effect Transistors

Directory of Open Access Journals (Sweden)

Kuiyu Zhu

2015-08-01

Full Text Available Primary hepatic carcinoma (PHC is one of the most common malignancies worldwide, resulting in death within six to 20 months. The survival rate can be improved by effective treatments when diagnosed at an early stage. The α-fetoprotein (AFP and carcinoembryonic antigen (CEA have been identified as markers that are expressed at higher levels in PHC patients. In this study, we employed silicon nanowire field-effect transistors (SiNW-FETs with polydimethylsiloxane (PDMS microfluidic channels to simultaneously detect AFP and CEA in desalted human serum. Dual-channel PDMS was first utilized for the selective modification of AFP and CEA antibodies on SiNWs, while single-channel PDMS offers faster and more sensitive detection of AFP and CEA in serum. During the SiNW modification process, 0.1% BSA was utilized to minimize nonspecific protein binding from serum. The linear dynamic ranges for the AFP and CEA detection were measured to be 500 fg/mL to 50 ng/mL and 50 fg/mL to 10 ng/mL, respectively. Our work demonstrates the promising potential of fabricated SiNW-FETs as a direct detection kit for multiple tumor markers in serum; therefore, it provides a chance for early stage diagnose and, hence, more effective treatments for PHC patients.

Silicon nanowire structures as high-sensitive pH-sensors

International Nuclear Information System (INIS)

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

2012-01-01

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

Transport Phenomena in Nanowires, Nanotubes, and Other Low-Dimensional Systems

KAUST Repository

Montes, Enrique

2017-01-01

Nanoscale materials are not new in either nature or physics. However, the recent technological improvements have given scientists new tools to understand and quantify phenomena that occur naturally due to quantum confinement effects. In general, these phenomena induce remarkable optical, magnetic, and electronic properties in nanoscale materials in contrast to their bulk counterpart. In addition, scientists have recently developed the necessary tools to control and exploit these properties in electronic devices, in particular field effect transistors, magnetic memories, and gas sensors. In the present thesis we implement theoretical and computational tools for analyzing the ground state and electronic transport properties of nanoscale materials and their performance in electronic devices. The ground state properties are studied within density functional theory using the SIESTA code, whereas the transport properties are investigated using the non-equilibrium Green\\'s functions formalism implemented in the SMEAGOL code. First we study Si-based systems, as Si nanowires are believed to be important building blocks of the next generation of electronic devices. We derive the electron transport properties of Si nanowires connected to Au electrodes and their dependence on the nanowire growth direction, diameter, and length. At equilibrium Au-nanowire distance we find strong electronic coupling between electrodes and nanowire, resulting in low contact resistance. For the tunneling regime, the decay of the conductance with the nanowire length is rationalized using the complex band structure. The nanowires grown along the (110) direction show the smallest decay and the largest conductance and current. Due to the high spin coherence in Si, Si nanowires represent an interesting platform for spin devices. Therefore, we built a magnetic tunneling junction by connecting a (110) Si nanowire to ferromagnetic Fe electrodes. We have find a substantial low bias magnetoresistance of

Atomic-Resolution Spectrum Imaging of Semiconductor Nanowires.

Science.gov (United States)

Zamani, Reza R; Hage, Fredrik S; Lehmann, Sebastian; Ramasse, Quentin M; Dick, Kimberly A

2018-03-14

Over the past decade, III-V heterostructure nanowires have attracted a surge of attention for their application in novel semiconductor devices such as tunneling field-effect transistors (TFETs). The functionality of such devices critically depends on the specific atomic arrangement at the semiconductor heterointerfaces. However, most of the currently available characterization techniques lack sufficient spatial resolution to provide local information on the atomic structure and composition of these interfaces. Atomic-resolution spectrum imaging by means of electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) is a powerful technique with the potential to resolve structure and chemical composition with sub-angstrom spatial resolution and to provide localized information about the physical properties of the material at the atomic scale. Here, we demonstrate the use of atomic-resolution EELS to understand the interface atomic arrangement in three-dimensional heterostructures in semiconductor nanowires. We observed that the radial interfaces of GaSb-InAs heterostructure nanowires are atomically abrupt, while the axial interface in contrast consists of an interfacial region where intermixing of the two compounds occurs over an extended spatial region. The local atomic configuration affects the band alignment at the interface and, hence, the charge transport properties of devices such as GaSb-InAs nanowire TFETs. STEM-EELS thus represents a very promising technique for understanding nanowire physical properties, such as differing electrical behavior across the radial and axial heterointerfaces of GaSb-InAs nanowires for TFET applications.

Decoupling single nanowire mobilities limited by surface scattering and bulk impurity scattering

International Nuclear Information System (INIS)

Khanal, D. R.; Levander, A. X.; Wu, J.; Yu, K. M.; Liliental-Weber, Z.; Walukiewicz, W.; Grandal, J.; Sanchez-Garcia, M. A.; Calleja, E.

2011-01-01

We demonstrate the isolation of two free carrier scattering mechanisms as a function of radial band bending in InN nanowires via universal mobility analysis, where effective carrier mobility is measured as a function of effective electric field in a nanowire field-effect transistor. Our results show that Coulomb scattering limits effective mobility at most effective fields, while surface roughness scattering only limits mobility under very high internal electric fields. High-energy α particle irradiation is used to vary the ionized donor concentration, and the observed decrease in mobility and increase in donor concentration are compared to Hall effect results of high-quality InN thin films. Our results show that for nanowires with relatively high doping and large diameters, controlling Coulomb scattering from ionized dopants should be given precedence over surface engineering when seeking to maximize nanowire mobility.

Tunneling and Transport in Nanowires

Energy Technology Data Exchange (ETDEWEB)

Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

2016-08-16

The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO₃. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

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

DEFF Research Database (Denmark)

Liu, Yi-Chi; Rieben, Nathalie Ines; Iversen, Lars

2010-01-01

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 reco...

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

Science.gov (United States)

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

2017-03-01

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

Semiconductor nanowires and templates for electronic applications

Energy Technology Data Exchange (ETDEWEB)

Ying, Xiang

2009-07-15

catalyzed germanium nanowires, a small process window has been determined where high aspect-ratio nanowires show single crystalline structure. Compositional analysis has been performed via electron energy loss spectroscopy (EELS) to monitor the presence of indium and bismuth in the nanowires. Both catalysts could be identified, validating their role as catalysts. A combined atomic force microscopy (AFM) and Raman spectroscopy characterization on single core-shell nanowires gives clear evidence of finite-size effects on the electron-phonon coupling, as well as the presence of strain. Field effect transistors were fabricated using gold, bismuth and indium catalyzed germanium nanowires. Initial room-temperature and temperature dependent transport measurements on gold and bismuth catalyzed nanowires show field effects. Indium catalyzed germanium nanowires show insulating behavior. (orig.)

Engineering Nanowire n-MOSFETs at L_{g}<8 nm

Science.gov (United States)

Mehrotra, Saumitra R.; Kim, SungGeun; Kubis, Tillmann; Povolotskyi, Michael; Lundstrom, Mark S.; Klimeck, Gerhard

2013-07-01

As metal-oxide-semiconductor field-effect transistors (MOSFET) channel lengths (Lg) are scaled to lengths shorter than Lg<8 nm source-drain tunneling starts to become a major performance limiting factor. In this scenario a heavier transport mass can be used to limit source-drain (S-D) tunneling. Taking InAs and Si as examples, it is shown that different heavier transport masses can be engineered using strain and crystal orientation engineering. Full-band extended device atomistic quantum transport simulations are performed for nanowire MOSFETs at Lg<8 nm in both ballistic and incoherent scattering regimes. In conclusion, a heavier transport mass can indeed be advantageous in improving ON state currents in ultra scaled nanowire MOSFETs.

Dimensional optimization of nanowire--complementary metal oxide--semiconductor inverter.

Science.gov (United States)

Hashim, Yasir; Sidek, Othman

2013-01-01

This study is the first to demonstrate dimensional optimization of nanowire-complementary metal-oxide-semiconductor inverter. Noise margins and inflection voltage of transfer characteristics are used as limiting factors in this optimization. Results indicate that optimization depends on both dimensions ratio and digital voltage level (Vdd). Diameter optimization reveals that when Vdd increases, the optimized value of (Dp/Dn) decreases. Channel length optimization results show that when Vdd increases, the optimized value of Ln decreases and that of (Lp/Ln) increases. Dimension ratio optimization reveals that when Vdd increases, the optimized value of Kp/Kn decreases, and silicon nanowire transistor with suitable dimensions (higher Dp and Ln with lower Lp and Dn) can be fabricated.

Long term stability of nanowire nanoelectronics in physiological environments.

Science.gov (United States)

Zhou, Wei; Dai, Xiaochuan; Fu, Tian-Ming; Xie, Chong; Liu, Jia; Lieber, Charles M

2014-03-12

Nanowire nanoelectronic devices have been exploited as highly sensitive subcellular resolution detectors for recording extracellular and intracellular signals from cells, as well as from natural and engineered/cyborg tissues, and in this capacity open many opportunities for fundamental biological research and biomedical applications. Here we demonstrate the capability to take full advantage of the attractive capabilities of nanowire nanoelectronic devices for long term physiological studies by passivating the nanowire elements with ultrathin metal oxide shells. Studies of Si and Si/aluminum oxide (Al2O3) core/shell nanowires in physiological solutions at 37 °C demonstrate long-term stability extending for at least 100 days in samples coated with 10 nm thick Al2O3 shells. In addition, investigations of nanowires configured as field-effect transistors (FETs) demonstrate that the Si/Al2O3 core/shell nanowire FETs exhibit good device performance for at least 4 months in physiological model solutions at 37 °C. The generality of this approach was also tested with in studies of Ge/Si and InAs nanowires, where Ge/Si/Al2O3 and InAs/Al2O3 core/shell materials exhibited stability for at least 100 days in physiological model solutions at 37 °C. In addition, investigations of hafnium oxide-Al2O3 nanolaminated shells indicate the potential to extend nanowire stability well beyond 1 year time scale in vivo. These studies demonstrate that straightforward core/shell nanowire nanoelectronic devices can exhibit the long term stability needed for a range of chronic in vivo studies in animals as well as powerful biomedical implants that could improve monitoring and treatment of disease.

Light-gated single CdSe nanowire transistor: photocurrent saturation and band gap extraction

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yang, E-mail: yangzh08@gmail.com; Chakraborty, Ritun; Kudera, Stefan; Krahne, Roman, E-mail: roman.krahne@iit.it [Istituto Italiano di Tecnologia, Nanochemistry department (Italy)

2015-11-15

CdSe nanowires are popular building blocks for many optoelectronic devices mainly owing to their direct band gap in the visible range of the spectrum. Here we investigate the optoelectronic properties of single CdSe nanowires fabricated by colloidal synthesis, in terms of their photocurrent–voltage characteristics and photoconductivity spectra recorded at 300 and 18 K. The photocurrent is identified as the secondary photocurrent, which gives rise to a photoconductive gain of ∼35. We observe a saturation of the photocurrent beyond a certain voltage bias that can be related to the finite drift velocity of electrons. From the photoconductivity spectra, we determine the band gap energy of the nanowires as ∼1.728 eV, and we resolve low-energy peaks that can be associated with sub-bandgap states.Graphical Abstract.

Pseudopotential-based electron quantum transport: Theoretical formulation and application to nanometer-scale silicon nanowire transistors

Energy Technology Data Exchange (ETDEWEB)

Fang, Jingtian, E-mail: jingtian.fang@utdallas.edu; Vandenberghe, William G.; Fu, Bo; Fischetti, Massimo V. [Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080 (United States)

2016-01-21

We present a formalism to treat quantum electronic transport at the nanometer scale based on empirical pseudopotentials. This formalism offers explicit atomistic wavefunctions and an accurate band structure, enabling a detailed study of the characteristics of devices with a nanometer-scale channel and body. Assuming externally applied potentials that change slowly along the electron-transport direction, we invoke the envelope-wavefunction approximation to apply the open boundary conditions and to develop the transport equations. We construct the full-band open boundary conditions (self-energies of device contacts) from the complex band structure of the contacts. We solve the transport equations and present the expressions required to calculate the device characteristics, such as device current and charge density. We apply this formalism to study ballistic transport in a gate-all-around (GAA) silicon nanowire field-effect transistor with a body-size of 0.39 nm, a gate length of 6.52 nm, and an effective oxide thickness of 0.43 nm. Simulation results show that this device exhibits a subthreshold slope (SS) of ∼66 mV/decade and a drain-induced barrier-lowering of ∼2.5 mV/V. Our theoretical calculations predict that low-dimensionality channels in a 3D GAA architecture are able to meet the performance requirements of future devices in terms of SS swing and electrostatic control.

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

Directory of Open Access Journals (Sweden)

Shen-Ming Chen

2008-01-01

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

Scalable fabrication of self-aligned graphene transistors and circuits on glass.

Science.gov (United States)

Liao, Lei; Bai, Jingwei; Cheng, Rui; Zhou, Hailong; Liu, Lixin; Liu, Yuan; Huang, Yu; Duan, Xiangfeng

2012-06-13

Graphene transistors are of considerable interest for radio frequency (rf) applications. High-frequency graphene transistors with the intrinsic cutoff frequency up to 300 GHz have been demonstrated. However, the graphene transistors reported to date only exhibit a limited extrinsic cutoff frequency up to about 10 GHz, and functional graphene circuits demonstrated so far can merely operate in the tens of megahertz regime, far from the potential the graphene transistors could offer. Here we report a scalable approach to fabricate self-aligned graphene transistors with the extrinsic cutoff frequency exceeding 50 GHz and graphene circuits that can operate in the 1-10 GHz regime. The devices are fabricated on a glass substrate through a self-aligned process by using chemical vapor deposition (CVD) grown graphene and a dielectrophoretic assembled nanowire gate array. The self-aligned process allows the achievement of unprecedented performance in CVD graphene transistors with a highest transconductance of 0.36 mS/μm. The use of an insulating substrate minimizes the parasitic capacitance and has therefore enabled graphene transistors with a record-high extrinsic cutoff frequency (> 50 GHz) achieved to date. The excellent extrinsic cutoff frequency readily allows configuring the graphene transistors into frequency doubling or mixing circuits functioning in the 1-10 GHz regime, a significant advancement over previous reports (∼20 MHz). The studies open a pathway to scalable fabrication of high-speed graphene transistors and functional circuits and represent a significant step forward to graphene based radio frequency devices.

Highly effective field-effect mobility amorphous InGaZnO TFT mediated by directional silver nanowire arrays.

Science.gov (United States)

Liu, Hung-Chuan; Lai, Yi-Chun; Lai, Chih-Chung; Wu, Bing-Shu; Zan, Hsiao-Wen; Yu, Peichen; Chueh, Yu-Lun; Tsai, Chuang-Chuang

2015-01-14

In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.

Radiation Effects in III-V Nanowire Devices

Science.gov (United States)

2016-09-01

fabrication of an in-plane nanowire (NW) GaAs metal-oxide-semiconductor field- effect transistor (MOSFET) by focused -ion beam (FIB) etching and chemical...8725 John J. Kingman Road, MS 6201 Fort Belvoir, VA 22060-6201 T E C H N IC A L R E P O R T DTRA-TR-16-94 Radiation Effects in III-V...5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING / MONITORING AGENCY

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

Science.gov (United States)

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

2016-01-13

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

Anisotropic transport properties of quasiballistic InAs nanowires under high magnetic field

Science.gov (United States)

Vigneau, Florian; Zeng, Zaiping; Escoffier, Walter; Caroff, Philippe; Leturcq, Renaud; Niquet, Yann-Michel; Raquet, Bertrand; Goiran, Michel

2018-03-01

The magnetoconductance of a long channel InAs nanowire based field effect transistor in the quasiballistic regime under large magnetic field is investigated. The quasi-1D nanowire is fully characterized by a bias voltage spectroscopy and measurements under magnetic field up to 50 T applied either perpendicular or parallel to the nanowire axis lifting the spin and orbital degeneracies of the subbands. Under normal magnetic field, the conductance shows quantized steps due to the backscattering reduction and a decrease due to depopulation of the 1D modes. Under axial magnetic field, a quasioscillatory behavior is evidenced due to the coupling of the magnetic field with the angular momentum of the wave function. In addition the formation of cyclotron orbits is highlighted under high magnetic field. The experimental results are compared with theoretical calculation of the 1D band structure and related parameters.

Substrate and Mg doping effects in GaAs nanowires

Directory of Open Access Journals (Sweden)

Perumal Kannappan

2017-10-01

Full Text Available Mg doping of GaAs nanowires has been established as a viable alternative to Be doping in order to achieve p-type electrical conductivity. Although reports on the optical properties are available, few reports exist about the physical properties of intermediate-to-high Mg doping in GaAs nanowires grown by molecular beam epitaxy (MBE on GaAs(111B and Si(111 substrates. In this work, we address this topic and present further understanding on the fundamental aspects. As the Mg doping was increased, structural and optical investigations revealed: i a lower influence of the polytypic nature of the GaAs nanowires on their electronic structure; ii a considerable reduction of the density of vertical nanowires, which is almost null for growth on Si(111; iii the occurrence of a higher WZ phase fraction, in particular for growth on Si(111; iv an increase of the activation energy to release the less bound carrier in the radiative state from nanowires grown on GaAs(111B; and v a higher influence of defects on the activation of nonradiative de-excitation channels in the case of nanowires only grown on Si(111. Back-gate field effect transistors were fabricated with individual nanowires and the p-type electrical conductivity was measured with free hole concentration ranging from 2.7 × 1016 cm−3 to 1.4 × 1017 cm−3. The estimated electrical mobility was in the range ≈0.3–39 cm2/Vs and the dominant scattering mechanism is ascribed to the WZ/ZB interfaces. Electrical and optical measurements showed a lower influence of the polytypic structure of the nanowires on their electronic structure. The involvement of Mg in one of the radiative transitions observed for growth on the Si(111 substrate is suggested.

Quantum phase slip interference device based on a shaped superconducting nanowire

Energy Technology Data Exchange (ETDEWEB)

Zorin, Alexander; Hongisto, Terhi [Physikalisch-Technische Bundesanstalt, 38116 Braunschweig (Germany)

2012-07-01

As was predicted by Mooij and Nazarov, the superconducting nanowires may exhibit, depending on the impedance of external electromagnetic environment, not only quantum slips of phase, but also the quantum-mechanically dual effect of coherent transfer of single Cooper pairs. We propose and realize a transistor-like superconducting circuit including two serially connected segments of a narrow (10 nm by 18 nm) nanowire joint by a wider segment with a capacitively coupled gate in between. This circuit is made of amorphous NbSi film and embedded in a network of on-chip Cr microresistors ensuring a high external impedance (>>h/e{sup 2}∼25.8 kΩ) and, eventually, a charge bias regime. Virtual quantum phase slips in two narrow segments of the wire lead in this case to quantum interference of voltages on these segments making this circuit dual to the dc SQUID. Our samples demonstrated appreciable Coulomb blockade voltage (analog of critical current of the SQUID) and remarkable periodic modulation of this blockade by an electrostatic gate (analog of flux modulation in the SQUID). The obtained experimental results and the model of this QPS transistor will be presented.

Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy

International Nuclear Information System (INIS)

Joyce, Hannah J; Docherty, Callum J; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B; Gao Qiang; Tan, H Hoe; Jagadish, Chennupati

2013-01-01

We have performed a comparative study of ultrafast charge carrier dynamics in a range of III–V nanowires using optical pump–terahertz probe spectroscopy. This versatile technique allows measurement of important parameters for device applications, including carrier lifetimes, surface recombination velocities, carrier mobilities and donor doping levels. GaAs, InAs and InP nanowires of varying diameters were measured. For all samples, the electronic response was dominated by a pronounced surface plasmon mode. Of the three nanowire materials, InAs nanowires exhibited the highest electron mobilities of 6000 cm 2 V −1 s −1 , which highlights their potential for high mobility applications, such as field effect transistors. InP nanowires exhibited the longest carrier lifetimes and the lowest surface recombination velocity of 170 cm s −1 . This very low surface recombination velocity makes InP nanowires suitable for applications where carrier lifetime is crucial, such as in photovoltaics. In contrast, the carrier lifetimes in GaAs nanowires were extremely short, of the order of picoseconds, due to the high surface recombination velocity, which was measured as 5.4 × 10 5   cm s −1 . These findings will assist in the choice of nanowires for different applications, and identify the challenges in producing nanowires suitable for future electronic and optoelectronic devices. (paper)

The Electrostatically Formed Nanowire: A Novel Platform for Gas-Sensing Applications

Directory of Open Access Journals (Sweden)

Gil Shalev

2017-02-01

Full Text Available The electrostatically formed nanowire (EFN gas sensor is based on a multiple-gate field-effect transistor with a conducting nanowire, which is not defined physically; rather, the nanowire is defined electrostatically post-fabrication, by using appropriate biasing of the different surrounding gates. The EFN is fabricated by using standard silicon processing technologies with relaxed design rules and, thereby, supports the realization of a low-cost and robust gas sensor, suitable for mass production. Although the smallest lithographic definition is higher than half a micrometer, appropriate tuning of the biasing of the gates concludes a conducting channel with a tunable diameter, which can transform the conducting channel into a nanowire with a diameter smaller than 20 nm. The tunable size and shape of the nanowire elicits tunable sensing parameters, such as sensitivity, limit of detection, and dynamic range, such that a single EFN gas sensor can perform with high sensitivity and a broad dynamic range by merely changing the biasing configuration. The current work reviews the design of the EFN gas sensor, its fabrication considerations and process flow, means of electrical characterization, and preliminary sensing performance at room temperature, underlying the unique and advantageous tunable capability of the device.

Effective mass approximation versus full atomistic model to calculate the output characteristics of a gate-all-around germanium nanowire field effect transistor (GAA-GeNW-FET)

Science.gov (United States)

Bayani, Amir Hossein; Voves, Jan; Dideban, Daryoosh

2018-01-01

Here, we compare the output characteristics of a gate-all-around germanium nanowire field effect transistor (GAA-GeNW-FET) with 2.36 nm2 square cross-section area using tight-binding (TB) sp3d5s∗ model (full atomistic model (FAM)) and effective mass approximation (EMA). Synopsys/QuantumWise Atomistix ToolKit (ATK) and Silvaco Atlas3D are used to consider the TB model and EMA, respectively. Results show that EMA predicted only one quantum state (QS) for quantum transport, whereas FAM predicted three QSs. A cosine function behavior is obtained by both methods for the first quantum state. The calculated bandgap value by EMA is almost twice smaller than that of the FAM. Also, a fluctuating current is predicted by both methods but in different oscillation values.

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

Nanowire field-effect transistors for gas sensor applications

Science.gov (United States)

Constantinou, Marios

Sensing BTEX (Benzene, Ethylbenzene, Toluene, Xylene) pollutants is of utmost importance to reduce health risk and ensure public safety. The lack of sensitivity and selectivity of the current gas sensors and the limited number of available technologies in the field of BTEX-sensing raises the demand for the development of high-performance gas sensors for BTEX applications. The scope of this thesis is the fabrication and characterisation of high-quality field-effect transistors (FETs), with functionalised silicon nanowires (SiNWs), for the selective sensing of benzene vs. other BTEX gases. This research addresses three main challenges in SiNW FET-sensor device development: i) controllable and reproducible assembly of high-quality SiNWs for FET sensor devices using the method of dielectrophoresis (DEP), ii) almost complete elimination of harmful hysteresis effect in the SiNW FET current-voltage characteristics induced by surface states using DMF solvent, iii) selective sensing of benzene with up to ppb range of sensitivity using calix[4]arene-derivatives. It is experimentally demonstrated that frequency-controlled DEP is a powerful tool for the selection and collection of semiconducting SiNWs with advanced electrical and morphological properties, from a poly-disperse as-synthesised NWs. The DEP assembly method also leads to a controllable and reproducible fabrication of high-quality NW-based FETs. The results highlight the superiority of DEP, performed at high signal frequencies (5-20 MHz) to selectively assemble only high-quality NWs which can respond to such high DEP frequencies. The SiNW FETs, with NWs collected at high DEP frequencies, have high mobility (≈50 cm2 V-1 s-1), low sub-threshold-swing (≈1.26 V/decade), high on-current (up to 3 mA) and high on/off ratio (106-107). The DEP NW selection is also demonstrated using an industrially scalable method, to allow establishing of NW response characteristics to different DEP frequencies in a very short time

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

KAUST Repository

Zhai, Yujia

2012-11-26

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

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

KAUST Repository

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

2012-01-01

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

Pushing the Performance Limit of Sub-100 nm Molybdenum Disulfide Transistors.

Science.gov (United States)

Liu, Yuan; Guo, Jian; Wu, Yecun; Zhu, Enbo; Weiss, Nathan O; He, Qiyuan; Wu, Hao; Cheng, Hung-Chieh; Xu, Yang; Shakir, Imran; Huang, Yu; Duan, Xiangfeng

2016-10-12

Two-dimensional semiconductors (2DSCs) such as molybdenum disulfide (MoS 2 ) have attracted intense interest as an alternative electronic material in the postsilicon era. However, the ON-current density achieved in 2DSC transistors to date is considerably lower than that of silicon devices, and it remains an open question whether 2DSC transistors can offer competitive performance. A high current device requires simultaneous minimization of the contact resistance and channel length, which is a nontrivial challenge for atomically thin 2DSCs, since the typical low contact resistance approaches for 2DSCs either degrade the electronic properties of the channel or are incompatible with the fabrication process for short channel devices. Here, we report a new approach toward high-performance MoS 2 transistors by using a physically assembled nanowire as a lift-off mask to create ultrashort channel devices with pristine MoS 2 channel and self-aligned low resistance metal/graphene hybrid contact. With the optimized contact in short channel devices, we demonstrate sub-100 nm MoS 2 transistor delivering a record high ON-current of 0.83 mA/μm at 300 K and 1.48 mA/μm at 20 K, which compares well with that of silicon devices. Our study, for the first time, demonstrates that the 2DSC transistors can offer comparable performance to the 2017 target for silicon transistors in International Technology Roadmap for Semiconductors (ITRS), marking an important milestone in 2DSC electronics.

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors.

Science.gov (United States)

McAlpine, Michael C; Ahmad, Habib; Wang, Dunwei; Heath, James R

2007-05-01

The development of a robust method for integrating high-performance semiconductors on flexible plastics could enable exciting avenues in fundamental research and novel applications. One area of vital relevance is chemical and biological sensing, which if implemented on biocompatible substrates, could yield breakthroughs in implantable or wearable monitoring systems. Semiconducting nanowires (and nanotubes) are particularly sensitive chemical sensors because of their high surface-to-volume ratios. Here, we present a scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto plastic to yield highly ordered films for low-power sensor chips. The nanowires are excellent field-effect transistors, and, as sensors, exhibit parts-per-billion sensitivity to NO2, a hazardous pollutant. We also use SiO2 surface chemistries to construct a 'nano-electronic nose' library, which can distinguish acetone and hexane vapours via distributed responses. The excellent sensing performance coupled with bendable plastic could open up opportunities in portable, wearable or even implantable sensors.

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

Science.gov (United States)

McAlpine, Michael C.; Ahmad, Habib; Wang, Dunwei; Heath, James R.

2007-05-01

The development of a robust method for integrating high-performance semiconductors on flexible plastics could enable exciting avenues in fundamental research and novel applications. One area of vital relevance is chemical and biological sensing, which if implemented on biocompatible substrates, could yield breakthroughs in implantable or wearable monitoring systems. Semiconducting nanowires (and nanotubes) are particularly sensitive chemical sensors because of their high surface-to-volume ratios. Here, we present a scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto plastic to yield highly ordered films for low-power sensor chips. The nanowires are excellent field-effect transistors, and, as sensors, exhibit parts-per-billion sensitivity to NO2, a hazardous pollutant. We also use SiO2 surface chemistries to construct a `nano-electronic nose' library, which can distinguish acetone and hexane vapours via distributed responses. The excellent sensing performance coupled with bendable plastic could open up opportunities in portable, wearable or even implantable sensors.

Dimensional effects in semiconductor nanowires; Dimensionseffekte in Halbleiternanodraehten

Energy Technology Data Exchange (ETDEWEB)

Stichtenoth, Daniel

2008-06-23

. Furthermore, GaAs nanowires were implanted with zinc ions. Electrical measurements on individual nanowires show a conductivity rise by four orders of magnitude. This points to a successful p-type doping. In a lithographic process ZnO nanowires were fabricated to field effect transistors (FET). Depending on the diameter and processing these FETs show carrier concentrations up to 10{sup 20} cm{sup -3} and mobilities up to 4800 cm{sup 2}/(Vs). Finally, a simple scalable process for the production of ZnO nanowire light emitting diodes (LED) is presented. The electro-luminescence of the nanowire LED is dominated by near band gap transitions, i.e. in the UV. It can be explained by tunnel injection from the p-silicon substrate into the ZnO nanowires. The light is mainly emitted from the end faces of the nanowires. This way the diameter of the light sources is defined by the diameter of the nanowires. (orig.)

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

KAUST Repository

Wang, Zhong Lin

2010-11-01

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

A soft lithographic approach to fabricate InAs nanowire field-effect transistors

DEFF Research Database (Denmark)

Madsen, Morten; Lee, S. H.; Shin, S.-H.

2018-01-01

-down approach and an epitaxial layer transfer process, using MBE-grown ultrathin InAs as a source wafer. The width of the InAs nanowires was controlled using solvent-assisted nanoscale embossing (SANE), descumming, and etching processes. By optimizing these processes, NWs with a width less than 50 nm were...

Variability study of Si nanowire FETs with different junction gradients

Directory of Open Access Journals (Sweden)

Jun-Sik Yoon

2016-01-01

Full Text Available Random dopant fluctuation effects of gate-all-around Si nanowire field-effect transistors (FETs are investigated in terms of different diameters and junction gradients. The nanowire FETs with smaller diameters or shorter junction gradients increase relative variations of the drain currents and the mismatch of the drain currents between source-drain and drain-source bias change in the saturation regime. Smaller diameters decreased current drivability critically compared to standard deviations of the drain currents, thus inducing greater relative variations of the drain currents. Shorter junction gradients form high potential barriers in the source-side lightly-doped extension regions at on-state, which determines the magnitude of the drain currents and fluctuates the drain currents greatly under thermionic-emission mechanism. On the other hand, longer junction gradients affect lateral field to fluctuate the drain currents greatly. These physical phenomena coincide with correlations of the variations between drain currents and electrical parameters such as threshold voltages and parasitic resistances. The nanowire FETs with relatively-larger diameters and longer junction gradients without degrading short channel characteristics are suggested to minimize the relative variations and the mismatch of the drain currents.

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.

Group IV nanotube transistors for next generation ubiquitous computing

KAUST Repository

Fahad, Hossain M.

2014-06-04

Evolution in transistor technology from increasingly large power consuming single gate planar devices to energy efficient multiple gate non-planar ultra-narrow (< 20 nm) fins has enhanced the scaling trend to facilitate doubling performance. However, this performance gain happens at the expense of arraying multiple devices (fins) per operation bit, due to their ultra-narrow dimensions (width) originated limited number of charges to induce appreciable amount of drive current. Additionally arraying degrades device off-state leakage and increases short channel characteristics, resulting in reduced chip level energy-efficiency. In this paper, a novel nanotube device (NTFET) topology based on conventional group IV (Si, SiGe) channel materials is discussed. This device utilizes a core/shell dual gate strategy to capitalize on the volume-inversion properties of an ultra-thin (< 10 nm) group IV nanotube channel to minimize leakage and short channel effects while maximizing performance in an area-efficient manner. It is also shown that the NTFET is capable of providing a higher output drive performance per unit chip area than an array of gate-all-around nanowires, while maintaining the leakage and short channel characteristics similar to that of a single gate-all-around nanowire, the latter being the most superior in terms of electrostatic gate control. In the age of big data and the multitude of devices contributing to the internet of things, the NTFET offers a new transistor topology alternative with maximum benefits from performance-energy efficiency-functionality perspective. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Self-limited plasmonic welding of silver nanowire junctions

KAUST Repository

Garnett, Erik C.

2012-02-05

Nanoscience provides many strategies to construct high-performance materials and devices, including solar cells, thermoelectrics, sensors, transistors, and transparent electrodes. Bottom-up fabrication facilitates large-scale chemical synthesis without the need for patterning and etching processes that waste material and create surface defects. However, assembly and contacting procedures still require further development. Here, we demonstrate a light-induced plasmonic nanowelding technique to assemble metallic nanowires into large interconnected networks. The small gaps that form naturally at nanowire junctions enable effective light concentration and heating at the point where the wires need to be joined together. The extreme sensitivity of the heating efficiency on the junction geometry causes the welding process to self-limit when a physical connection between the wires is made. The localized nature of the heating prevents damage to low-thermal-budget substrates such as plastics and polymer solar cells. This work opens new avenues to control light, heat and mass transport at the nanoscale. © 2012 Macmillan Publishers Limited. All rights reserved.

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

Synthesis and properties of silicon nanowire devices

Science.gov (United States)

Byon, Kumhyo

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

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.

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

Science.gov (United States)

Wen, Feng; Tutuc, Emanuel

2018-01-10

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

The impact of silicon nano-wire technology on the design of single-work-function CMOS transistors and circuits

International Nuclear Information System (INIS)

Bindal, Ahmet; Hamedi-Hagh, Sotoudeh

2006-01-01

This three-dimensional exploratory study on vertical silicon wire MOS transistors with metal gates and undoped bodies demonstrates that these transistors dissipate less power and occupy less layout area while producing comparable transient response with respect to the state-of-the-art bulk and SOI technologies. The study selects a single metal gate work function for both NMOS and PMOS transistors to alleviate fabrication difficulties and then determines a common device geometry to produce an OFF current smaller than 1 pA for each transistor. Once an optimum wire radius and effective channel length is determined, DC characteristics including threshold voltage roll-off, drain-induced barrier lowering and sub-threshold slope of each transistor are measured. Simple CMOS gates such as an inverter, two- and three-input NAND, NOR and XOR gates and a full adder, composed of the optimum NMOS and PMOS transistors, are built to measure transient performance, power dissipation and layout area. Simulation results indicate that worst-case transient time and worst-case delay are 1.63 and 1.46 ps, respectively, for a two-input NAND gate and 7.51 and 7.43 ps, respectively, for a full adder for a fan-out of six transistor gates (24 aF). Worst-case power dissipation is 62.1 nW for a two-input NAND gate and 118.1 nW for a full adder at 1 GHz for the same output capacitance. The layout areas are 0.0066 μm 2 for the two-input NAND gate and 0.049 μm 2 for the full adder circuits

Room-Temperature Quantum Ballistic Transport in Monolithic Ultrascaled Al-Ge-Al Nanowire Heterostructures.

Science.gov (United States)

Sistani, Masiar; Staudinger, Philipp; Greil, Johannes; Holzbauer, Martin; Detz, Hermann; Bertagnolli, Emmerich; Lugstein, Alois

2017-08-09

Conductance quantization at room temperature is a key requirement for the utilizing of ballistic transport for, e.g., high-performance, low-power dissipating transistors operating at the upper limit of "on"-state conductance or multivalued logic gates. So far, studying conductance quantization has been restricted to high-mobility materials at ultralow temperatures and requires sophisticated nanostructure formation techniques and precise lithography for contact formation. Utilizing a thermally induced exchange reaction between single-crystalline Ge nanowires and Al pads, we achieved monolithic Al-Ge-Al NW heterostructures with ultrasmall Ge segments contacted by self-aligned quasi one-dimensional crystalline Al leads. By integration in electrostatically modulated back-gated field-effect transistors, we demonstrate the first experimental observation of room temperature quantum ballistic transport in Ge, favorable for integration in complementary metal-oxide-semiconductor platform technology.

Hole-dominated transport in InSb nanowires grown on high-quality InSb films

Energy Technology Data Exchange (ETDEWEB)

Algarni, Zaina; George, David; Singh, Abhay; Lin, Yuankun; Philipose, U., E-mail: usha.philipose@unt.edu [University of North Texas, Department of Physics (United States)

2016-12-15

We have developed an effective strategy for synthesizing p-type indium antimonide (InSb) nanowires on a thin film of InSb grown on glass substrate. The InSb films were grown by a chemical reaction between Sb{sub 2}S{sub 3} and In and were characterized by structural, compositional, and optical studies. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal that the surface of the substrate is covered with a polycrystalline InSb film comprised of sub-micron sized InSb islands. Energy dispersive X-ray (EDX) results show that the film is stoichiometric InSb. The optical constants of the InSb film, characterized using a variable-angle spectroscopic ellipsometer (VASE) shows a maximum value for refractive index at 3.7 near 1.8 eV, and the extinction coefficient (k) shows a maximum value 3.3 near 4.1 eV. InSb nanowires were subsequently grown on the InSb film with 20 nm sized Au nanoparticles functioning as the metal catalyst initiating nanowire growth. The InSb nanowires with diameters in the range of 40–60 nm exhibit good crystallinity and were found to be rich in Sb. High concentrations of anions in binary semiconductors are known to introduce acceptor levels within the band gap. This un-intentional doping of the InSb nanowire resulting in hole-dominated transport in the nanowires is demonstrated by the fabrication of a p-channel nanowire field effect transistor. The hole concentration and field effect mobility are estimated to be ≈1.3 × 10{sup 17} cm{sup −3} and 1000 cm{sup 2} V{sup −1} s{sup −1}, respectively, at room temperature, values that are particularly attractive for the technological implications of utilizing p-InSb nanowires in CMOS electronics.

Hole-dominated transport in InSb nanowires grown on high-quality InSb films

Science.gov (United States)

Algarni, Zaina; George, David; Singh, Abhay; Lin, Yuankun; Philipose, U.

2016-12-01

We have developed an effective strategy for synthesizing p-type indium antimonide (InSb) nanowires on a thin film of InSb grown on glass substrate. The InSb films were grown by a chemical reaction between S b 2 S 3 and I n and were characterized by structural, compositional, and optical studies. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal that the surface of the substrate is covered with a polycrystalline InSb film comprised of sub-micron sized InSb islands. Energy dispersive X-ray (EDX) results show that the film is stoichiometric InSb. The optical constants of the InSb film, characterized using a variable-angle spectroscopic ellipsometer (VASE) shows a maximum value for refractive index at 3.7 near 1.8 eV, and the extinction coefficient (k) shows a maximum value 3.3 near 4.1 eV. InSb nanowires were subsequently grown on the InSb film with 20 nm sized Au nanoparticles functioning as the metal catalyst initiating nanowire growth. The InSb nanowires with diameters in the range of 40-60 nm exhibit good crystallinity and were found to be rich in Sb. High concentrations of anions in binary semiconductors are known to introduce acceptor levels within the band gap. This un-intentional doping of the InSb nanowire resulting in hole-dominated transport in the nanowires is demonstrated by the fabrication of a p-channel nanowire field effect transistor. The hole concentration and field effect mobility are estimated to be ≈1.3 × 1017 cm-3 and 1000 cm2 V-1 s-1, respectively, at room temperature, values that are particularly attractive for the technological implications of utilizing p-InSb nanowires in CMOS electronics.

Unique Characteristics of Vertical Carbon Nanotube Field-effect Transistors on Silicon

KAUST Repository

Li, Jingqi

2014-07-01

A vertical carbon nanotube field-effect transistor (CNTFET) based on silicon (Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled carbon nanotube (SWNT) and an n-type Si nanowire in series construct the channel of the transistor. The CNTFET presents ambipolar characteristics at positive drain voltage (Vd) and n-type characteristics at negative Vd. The current is significantly influenced by the doping level of n-Si and the SWNT band gap. The n-branch current of the ambipolar characteristics increases with increasing doping level of the n-Si while the p-branch current decreases. The SWNT band gap has the same influence on the p-branch current at a positive Vd and n-type characteristics at negative Vd. The lower the SWNT band gap, the higher the current. However, it has no impact on the n-branch current in the ambipolar characteristics. Thick oxide is found to significantly degrade the current and the subthreshold slope of the CNTFETs.

Unique Characteristics of Vertical Carbon Nanotube Field-effect Transistors on Silicon

KAUST Repository

Li, Jingqi; Yue, Weisheng; Guo, Zaibing; Yang, Yang; Wang, Xianbin; Syed, Ahad A.; Zhang, Yafei

2014-01-01

A vertical carbon nanotube field-effect transistor (CNTFET) based on silicon (Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled carbon nanotube (SWNT) and an n-type Si nanowire in series construct the channel of the transistor. The CNTFET presents ambipolar characteristics at positive drain voltage (Vd) and n-type characteristics at negative Vd. The current is significantly influenced by the doping level of n-Si and the SWNT band gap. The n-branch current of the ambipolar characteristics increases with increasing doping level of the n-Si while the p-branch current decreases. The SWNT band gap has the same influence on the p-branch current at a positive Vd and n-type characteristics at negative Vd. The lower the SWNT band gap, the higher the current. However, it has no impact on the n-branch current in the ambipolar characteristics. Thick oxide is found to significantly degrade the current and the subthreshold slope of the CNTFETs.

High-performance silicon nanowire bipolar phototransistors

Science.gov (United States)

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

2016-07-01

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

Manipulation of Optoelectronic Properties and Band Structure Engineering of Ultrathin Te Nanowires by Chemical Adsorption.

Science.gov (United States)

Roy, Ahin; Amin, Kazi Rafsanjani; Tripathi, Shalini; Biswas, Sangram; Singh, Abhishek K; Bid, Aveek; Ravishankar, N

2017-06-14

Band structure engineering is a powerful technique both for the design of new semiconductor materials and for imparting new functionalities to existing ones. In this article, we present a novel and versatile technique to achieve this by surface adsorption on low dimensional systems. As a specific example, we demonstrate, through detailed experiments and ab initio simulations, the controlled modification of band structure in ultrathin Te nanowires due to NO 2 adsorption. Measurements of the temperature dependence of resistivity of single ultrathin Te nanowire field-effect transistor (FET) devices exposed to increasing amounts of NO 2 reveal a gradual transition from a semiconducting to a metallic state. Gradual quenching of vibrational Raman modes of Te with increasing concentration of NO 2 supports the appearance of a metallic state in NO 2 adsorbed Te. Ab initio simulations attribute these observations to the appearance of midgap states in NO 2 adsorbed Te nanowires. Our results provide fundamental insights into the effects of ambient on the electronic structures of low-dimensional materials and can be exploited for designing novel chemical sensors.

Thermodynamics and kinetics of RNA tertiary structure formation in the junctionless hairpin ribozyme.

Science.gov (United States)

White, Neil A; Hoogstraten, Charles G

2017-09-01

The hairpin ribozyme consists of two RNA internal loops that interact to form the catalytically active structure. This docking transition is a rare example of intermolecular formation of RNA tertiary structure without coupling to helix annealing. We have used temperature-dependent surface plasmon resonance (SPR) to characterize the thermodynamics and kinetics of RNA tertiary structure formation for the junctionless form of the ribozyme, in which loops A and B reside on separate molecules. We find docking to be strongly enthalpy-driven and to be accompanied by substantial activation barriers for association and dissociation, consistent with the structural reorganization of both internal loops upon complex formation. Comparisons with the parallel analysis of a ribozyme variant carrying a 2'-O-methyl modification at the self-cleavage site and with published data in other systems reveal a surprising diversity of thermodynamic signatures, emphasizing the delicate balance of contributions to the free energy of formation of RNA tertiary structure. Copyright © 2017 Elsevier B.V. All rights reserved.

Transistor Effect in Improperly Connected Transistors.

Science.gov (United States)

Luzader, Stephen; Sanchez-Velasco, Eduardo

1996-01-01

Discusses the differences between the standard representation and a realistic representation of a transistor. Presents an experiment that helps clarify the explanation of the transistor effect and shows why transistors should be connected properly. (JRH)

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

Science.gov (United States)

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

2013-11-21

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

Contact resistance and overlapping capacitance in flexible sub-micron long oxide thin-film transistors for above 100 MHz operation

Energy Technology Data Exchange (ETDEWEB)

Münzenrieder, Niko, E-mail: muenzenrieder@ife.ee.ethz.ch; Salvatore, Giovanni A.; Petti, Luisa; Zysset, Christoph; Büthe, Lars; Vogt, Christian; Cantarella, Giuseppe; Tröster, Gerhard [Electronics Laboratory Swiss Federal Institute of Technology (ETH) Zürich, Gloriastrasse 35, 8092 Zürich (Switzerland)

2014-12-29

In recent years new forms of electronic devices such as electronic papers, flexible displays, epidermal sensors, and smart textiles have become reality. Thin-film transistors (TFTs) are the basic blocks of the circuits used in such devices and need to operate above 100 MHz to efficiently treat signals in RF systems and address pixels in high resolution displays. Beyond the choice of the semiconductor, i.e., silicon, graphene, organics, or amorphous oxides, the junctionless nature of TFTs and its geometry imply some limitations which become evident and important in devices with scaled channel length. Furthermore, the mechanical instability of flexible substrates limits the feature size of flexible TFTs. Contact resistance and overlapping capacitance are two parasitic effects which limit the transit frequency of transistors. They are often considered independent, while a deeper analysis of TFTs geometry imposes to handle them together; in fact, they both depend on the overlapping length (L{sub OV}) between source/drain and the gate contacts. Here, we conduct a quantitative analysis based on a large number of flexible ultra-scaled IGZO TFTs. Devices with three different values of overlap length and channel length down to 0.5 μm are fabricated to experimentally investigate the scaling behavior of the transit frequency. Contact resistance and overlapping capacitance depend in opposite ways on L{sub OV}. These findings establish routes for the optimization of the dimension of source/drain contact pads and suggest design guidelines to achieve megahertz operation in flexible IGZO TFTs and circuits.

SOI Transistor measurement techniques using body contacted transistors

International Nuclear Information System (INIS)

Worley, E.R.; Williams, R.

1989-01-01

Measurements of body contacted SOI transistors are used to isolate parameters of the back channel and island edge transistor. Properties of the edge and back channel transistor have been measured before and after X-ray irradiation (ARACOR). The unique properties of the edge transistor are shown to be a result of edge geometry as confirmed by a two dimensional transistor simulator

Synthesis of p-type GaN nanowires.

Science.gov (United States)

Kim, Sung Wook; Park, Youn Ho; Kim, Ilsoo; Park, Tae-Eon; Kwon, Byoung Wook; Choi, Won Kook; Choi, Heon-Jin

2013-09-21

GaN has been utilized in optoelectronics for two decades. However, p-type doping still remains crucial for realization of high performance GaN optoelectronics. Though Mg has been used as a p-dopant, its efficiency is low due to the formation of Mg-H complexes and/or structural defects in the course of doping. As a potential alternative p-type dopant, Cu has been recognized as an acceptor impurity for GaN. Herein, we report the fabrication of Cu-doped GaN nanowires (Cu:GaN NWs) and their p-type characteristics. The NWs were grown vertically via a vapor-liquid-solid (VLS) mechanism using a Au/Ni catalyst. Electrical characterization using a nanowire-field effect transistor (NW-FET) showed that the NWs exhibited n-type characteristics. However, with further annealing, the NWs showed p-type characteristics. A homo-junction structure (consisting of annealed Cu:GaN NW/n-type GaN thin film) exhibited p-n junction characteristics. A hybrid organic light emitting diode (OLED) employing the annealed Cu:GaN NWs as a hole injection layer (HIL) also demonstrated current injected luminescence. These results suggest that Cu can be used as a p-type dopant for GaN NWs.

Nano/CMOS architectures using a field-programmable nanowire interconnect

International Nuclear Information System (INIS)

Snider, Gregory S; Williams, R Stanley

2007-01-01

A field-programmable nanowire interconnect (FPNI) enables a family of hybrid nano/CMOS circuit architectures that generalizes the CMOL (CMOS/molecular hybrid) approach proposed by Strukov and Likharev, allowing for simpler fabrication, more conservative process parameters, and greater flexibility in the choice of nanoscale devices. The FPNI improves on a field-programmable gate array (FPGA) architecture by lifting the configuration bit and associated components out of the semiconductor plane and replacing them in the interconnect with nonvolatile switches, which decreases both the area and power consumption of the circuit. This is an example of a more comprehensive strategy for improving the efficiency of existing semiconductor technology: placing a level of intelligence and configurability in the interconnect can have a profound effect on integrated circuit performance, and can be used to significantly extend Moore's law without having to shrink the transistors. Compilation of standard benchmark circuits onto FPNI chip models shows reduced area (8 x to 25 x), reduced power, slightly lower clock speeds, and high defect tolerance-an FPNI chip with 20% defective junctions and 20% broken nanowires has an effective yield of 75% with no significant slowdown along the critical path, compared to a defect-free chip. Simulations show that the density and power improvements continue as both CMOS and nano fabrication parameters scale down, although the maximum clock rate decreases due to the high resistance of very small (<10 nm) metallic nanowires

Transistor data book

International Nuclear Information System (INIS)

1988-03-01

It introduces how to use this book. It lists transistor data and index, which are Type No, Cross index, Germanium PNP low power transistors, silicon NPN low power transistors, Germanium PNP high power transistors, Switching transistors, transistor arrays, Miscellaneous transistors, types with U.S military specifications, direct replacement transistors, suggested replacement transistors, schematic drawings, outline drawings, device number keys and manufacturer's logos.

Cylindrical Field Effect Transistor: A Full Volume Inversion Device

KAUST Repository

Fahad, Hossain M.

2010-12-01

The increasing demand for high performance as well as low standby power devices has been the main reason for the aggressive scaling of conventional CMOS transistors. Current devices are at the 32nm technology node. However, due to physical limitations as well as increase in short-channel effects, leakage, power dissipation, this scaling trend cannot continue and will eventually hit a barrier. In order to overcome this, alternate device topologies have to be considered altogether. Extensive research on ultra thin body double gate FETs and gate all around nanowire FETs has shown a lot of promise. Under strong inversion, these devices have demonstrated increased performance over their bulk counterparts. This is mainly attributed to full carrier inversion in the body. However, these devices are still limited by lithographic and processing challenges making them unsuitable for commercial production. This thesis explores a unique device structure called the CFET (Cylindrical Field Effect Transistors) which also like the above, relies on complete inversion of carriers in the body/bulk. Using dual gates; an outer and an inner gate, full-volume inversion is possible with benefits such as enhanced drive currents, high Ion/Ioff ratios and reduced short channel effects.

Growth of Horizonatal ZnO Nanowire Arrays on Any Substrate

KAUST Repository

Qin, Yong

2008-12-04

A general method is presented for growing laterally aligned and patterned ZnO nanowire (NW) arrays on any substrate as long as it is flat. The orientation control is achieved using the combined effect from ZnO seed layer and the catalytically inactive Cr (or Sn) layer for NW growth. The growth temperature (< 100 °C) is so low that the method can be applied to a wide range of substrates that can be inorganic, organic, single crystal, polycrystal, or amorphous. The laterally aligned ZnO NW arrays can be employed for various applications, such as gas sensor, field effect transistor, nanogenerator, and flexible electronics. © 2008 American Chemical Society.

High-performance integrated field-effect transistor-based sensors

Energy Technology Data Exchange (ETDEWEB)

Adzhri, R., E-mail: adzhri@gmail.com [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); Md Arshad, M.K., E-mail: mohd.khairuddin@unimap.edu.my [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); School of Microelectronic Engineering (SoME), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); Gopinath, Subash C.B., E-mail: subash@unimap.edu.my [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); School of Bioprocess Engineering (SBE), Universiti Malaysia Perlis (UniMAP), Arau, Perlis (Malaysia); Ruslinda, A.R., E-mail: ruslinda@unimap.edu.my [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); Fathil, M.F.M., E-mail: faris.fathil@gmail.com [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); Ayub, R.M., E-mail: ramzan@unimap.edu.my [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); Nor, M. Nuzaihan Mohd, E-mail: m.nuzaihan@unimap.edu.my [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia); Voon, C.H., E-mail: chvoon@unimap.edu.my [Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis (Malaysia)

2016-04-21

Field-effect transistors (FETs) have succeeded in modern electronics in an era of computers and hand-held applications. Currently, considerable attention has been paid to direct electrical measurements, which work by monitoring changes in intrinsic electrical properties. Further, FET-based sensing systems drastically reduce cost, are compatible with CMOS technology, and ease down-stream applications. Current technologies for sensing applications rely on time-consuming strategies and processes and can only be performed under recommended conditions. To overcome these obstacles, an overview is presented here in which we specifically focus on high-performance FET-based sensor integration with nano-sized materials, which requires understanding the interaction of surface materials with the surrounding environment. Therefore, we present strategies, material depositions, device structures and other characteristics involved in FET-based devices. Special attention was given to silicon and polyaniline nanowires and graphene, which have attracted much interest due to their remarkable properties in sensing applications. - Highlights: • Performance of FET-based biosensors for the detection of biomolecules is presented. • Silicon nanowire, polyaniline and graphene are the highlighted nanoscaled materials as sensing transducers. • The importance of surface material interaction with the surrounding environment is discussed. • Different device structure architectures for ease in fabrication and high sensitivity of sensing are presented.

High-performance integrated field-effect transistor-based sensors

International Nuclear Information System (INIS)

Adzhri, R.; Md Arshad, M.K.; Gopinath, Subash C.B.; Ruslinda, A.R.; Fathil, M.F.M.; Ayub, R.M.; Nor, M. Nuzaihan Mohd; Voon, C.H.

2016-01-01

Field-effect transistors (FETs) have succeeded in modern electronics in an era of computers and hand-held applications. Currently, considerable attention has been paid to direct electrical measurements, which work by monitoring changes in intrinsic electrical properties. Further, FET-based sensing systems drastically reduce cost, are compatible with CMOS technology, and ease down-stream applications. Current technologies for sensing applications rely on time-consuming strategies and processes and can only be performed under recommended conditions. To overcome these obstacles, an overview is presented here in which we specifically focus on high-performance FET-based sensor integration with nano-sized materials, which requires understanding the interaction of surface materials with the surrounding environment. Therefore, we present strategies, material depositions, device structures and other characteristics involved in FET-based devices. Special attention was given to silicon and polyaniline nanowires and graphene, which have attracted much interest due to their remarkable properties in sensing applications. - Highlights: • Performance of FET-based biosensors for the detection of biomolecules is presented. • Silicon nanowire, polyaniline and graphene are the highlighted nanoscaled materials as sensing transducers. • The importance of surface material interaction with the surrounding environment is discussed. • Different device structure architectures for ease in fabrication and high sensitivity of sensing are presented.

Single InAs/GaSb nanowire low-power CMOS inverter.

Science.gov (United States)

Dey, Anil W; Svensson, Johannes; Borg, B Mattias; Ek, Martin; Wernersson, Lars-Erik

2012-11-14

III-V semiconductors have so far predominately been employed for n-type transistors in high-frequency applications. This development is based on the advantageous transport properties and the large variety of heterostructure combinations in the family of III-V semiconductors. In contrast, reports on p-type devices with high hole mobility suitable for complementary metal-oxide-semiconductor (CMOS) circuits for low-power operation are scarce. In addition, the difficulty to integrate both n- and p-type devices on the same substrate without the use of complex buffer layers has hampered the development of III-V based digital logic. Here, inverters fabricated from single n-InAs/p-GaSb heterostructure nanowires are demonstrated in a simple processing scheme. Using undoped segments and aggressively scaled high-κ dielectric, enhancement mode operation suitable for digital logic is obtained for both types of transistors. State-of-the-art on- and off-state characteristics are obtained and the individual long-channel n- and p-type transistors exhibit minimum subthreshold swings of SS = 98 mV/dec and SS = 400 mV/dec, respectively, at V(ds) = 0.5 V. Inverter characteristics display a full signal swing and maximum gain of 10.5 with a small device-to-device variability. Complete inversion is measured at low frequencies although large parasitic capacitances deform the waveform at higher frequencies.

Intrinsically stretchable and healable semiconducting polymer for organic transistors.

Science.gov (United States)

Oh, Jin Young; Rondeau-Gagné, Simon; Chiu, Yu-Cheng; Chortos, Alex; Lissel, Franziska; Wang, Ging-Ji Nathan; Schroeder, Bob C; Kurosawa, Tadanori; Lopez, Jeffrey; Katsumata, Toru; Xu, Jie; Zhu, Chenxin; Gu, Xiaodan; Bae, Won-Gyu; Kim, Yeongin; Jin, Lihua; Chung, Jong Won; Tok, Jeffrey B-H; Bao, Zhenan

2016-11-17

Thin-film field-effect transistors are essential elements of stretchable electronic devices for wearable electronics. All of the materials and components of such transistors need to be stretchable and mechanically robust. Although there has been recent progress towards stretchable conductors, the realization of stretchable semiconductors has focused mainly on strain-accommodating engineering of materials, or blending of nanofibres or nanowires into elastomers. An alternative approach relies on using semiconductors that are intrinsically stretchable, so that they can be fabricated using standard processing methods. Molecular stretchability can be enhanced when conjugated polymers, containing modified side-chains and segmented backbones, are infused with more flexible molecular building blocks. Here we present a design concept for stretchable semiconducting polymers, which involves introducing chemical moieties to promote dynamic non-covalent crosslinking of the conjugated polymers. These non-covalent crosslinking moieties are able to undergo an energy dissipation mechanism through breakage of bonds when strain is applied, while retaining high charge transport abilities. As a result, our polymer is able to recover its high field-effect mobility performance (more than 1 square centimetre per volt per second) even after a hundred cycles at 100 per cent applied strain. Organic thin-film field-effect transistors fabricated from these materials exhibited mobility as high as 1.3 square centimetres per volt per second and a high on/off current ratio exceeding a million. The field-effect mobility remained as high as 1.12 square centimetres per volt per second at 100 per cent strain along the direction perpendicular to the strain. The field-effect mobility of damaged devices can be almost fully recovered after a solvent and thermal healing treatment. Finally, we successfully fabricated a skin-inspired stretchable organic transistor operating under deformations that might be

Strained Silicon Single Nanowire Gate-All-Around TFETs with Optimized Tunneling Junctions

Directory of Open Access Journals (Sweden)

Keyvan Narimani

2018-04-01

Full Text Available In this work, we demonstrate a strained Si single nanowire tunnel field effect transistor (TFET with gate-all-around (GAA structure yielding Ion-current of 15 μA/μm at the supply voltage of Vdd = 0.5V with linear onset at low drain voltages. The subthreshold swing (SS at room temperature shows an average of 76 mV/dec over 4 orders of drain current Id from 5 × 10−6 to 5 × 10−2 µA/µm Optimized devices also show excellent current saturation, an important feature for analog performance.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Mechanical behavior enhancement of ZnO nanowire by embedding different nanowires

Directory of Open Access Journals (Sweden)

Ali Vazinishayan

2018-06-01

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

Mechanical behavior enhancement of ZnO nanowire by embedding different nanowires

Science.gov (United States)

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

2018-06-01

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

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Probing the electrical properties of highly-doped Al:ZnO nanowire ensembles

KAUST Repository

Noriega, Rodrigo; Rivnay, Jonathan; Goris, Ludwig; Kälblein, Daniel; Klauk, Hagen; Kern, Klaus; Thompson, Linda M.; Palke, Aaron C.; Stebbins, Jonathan F.; Jokisaari, Jacob R.; Kusinski, Greg; Salleo, Alberto

2010-01-01

The analysis of transparent conducting oxide nanostructures suffers from a lack of high throughput yet quantitatively sensitive set of analytical techniques that can properly assess their electrical properties and serve both as characterization and diagnosis tools. This is addressed by applying a comprehensive set of characterization techniques to study the electrical properties of solution-grown Al-doped ZnO nanowires as a function of composition from 0 to 4 at. % Al:Zn. Carrier mobility and charge density extracted from sensitive optical absorption measurements are in agreement with those extracted from single-wire field-effect transistor devices. The mobility in undoped nanowires is 28 cm2 /V s and decreases to ∼14 cm2 /V s at the highest doping density, though the carrier density remains approximately constant (1020 cm-3) due to limited dopant activation or the creation of charge-compensating defects. Additionally, the local geometry of the Al dopant is studied by nuclear magnetic resonance, showing the occupation of a variety of dopant sites. © 2010 American Institute of Physics.

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-01-01

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

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

Science.gov (United States)

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

2016-01-13

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

Research Update: Nanoscale electrochemical transistors in correlated oxides

Directory of Open Access Journals (Sweden)

Teruo Kanki

2017-04-01

Full Text Available Large reversible changes of the electronic transport properties of solid-state oxide materials induced by electrochemical fields have received much attention as a new research avenue in iontronics. In this research update, dramatic transport changes in vanadium dioxide (VO2 nanowires were demonstrated by electric field-induced hydrogenation at room temperature through the nanogaps separated by humid air in a field-effect transistor structure with planar-type gates. This unique structure allowed us to investigate hydrogen intercalation and diffusion behavior in VO2 channels with respect to both time and space. Our results will contribute to further strategic researches to examine fundamental chemical and physical properties of devices and develop iontronic applications, as well as offering new directions to explore emerging functions for sensing, energy, and neuromorphologic devices combining ionic and electronic behaviors in solid-state materials.

Piezo-phototronic Boolean logic and computation using photon and strain dual-gated nanowire transistors.

Science.gov (United States)

Yu, Ruomeng; Wu, Wenzhuo; Pan, Caofeng; Wang, Zhaona; Ding, Yong; Wang, Zhong Lin

2015-02-04

Using polarization charges created at the metal-cadmium sulfide interface under strain to gate/modulate electrical transport and optoelectronic processes of charge carriers, the piezo-phototronic effect is applied to process mechanical and optical stimuli into electronic controlling signals. The cascade nanowire networks are demonstrated for achieving logic gates, binary computations, and gated D latches to store information carried by these stimuli. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Understanding channel and contact effects on transport in 1-dimensional nanotransistors.

Energy Technology Data Exchange (ETDEWEB)

Swartzentruber, Brian S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Delker, Collin James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Yoo, Jinkyoung [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Janes, David B. [Purdue Univ., West Lafayette, IN (United States)

2015-02-01

Nanowire transistors are generally formed by metal contacts to a uniformly doped nanowire. The transistor can be modeled as a series combination of resistances from both the channel and the contacts. In this study, a simple model is proposed consisting of a resistive channel in series with two Schottky metal-semiconductor contacts modeled using the WKB approximation. This model captures several phenomena commonly observed in nanowire transistor measurements, including the mobility as a function of gate potential, mobility reduction with respect to bulk mobility, and non-linearities in output characteristics. For example, the maximum measured mobility as a function of gate voltage in a nanowire transistor can be predicted based on the semiconductor bulk mobility in addition to barrier height and other properties of the contact. The model is then extended to nanowires with axial p-n junctions having an inde- pendent gate over each wire segment by splitting the channel resistance into a series component for each doping segment. Finally, the contact-channel model is applied to low-frequency noise analysis in nanowire devices, where the noise can be generated in both the channel and the contacts. Because contacts play a major, yet often neglected, role in nanowire transistor operation, they must be accounted for in order to extract meaningful parameters from I-V and noise measurements.

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.

Tunneling spectroscopy of a germanium quantum dot in single-hole transistors with self-aligned electrodes

International Nuclear Information System (INIS)

Chen, G-L; Kuo, David M T; Lai, W-T; Li, P-W

2007-01-01

We have fabricated a Ge quantum dot (QD) (∼10 nm) single-hole transistor with self-aligned electrodes using thermal oxidation of a SiGe-on-insulator nanowire based on FinFET technology. This fabricated device exhibits clear Coulomb blockade oscillations with large peak-to-valley ratio (PVCR) of 250-750 and negative differential conductance with PVCR of ∼12 at room temperature. This reveals that the gate-induced tunneling barrier lowering is effectively suppressed due to the self-aligned electrode structure. The magnitude of tunneling current spectra also reveals the coupling strengths between the energy levels of the Ge QD and electrodes

Axial Ge/Si nanowire heterostructure tunnel FETs

Energy Technology Data Exchange (ETDEWEB)

Picraux, Sanuel T [Los Alamos National Laboratory; Daych, Shadi A [Los Alamos National Laboratory

2010-01-01

The vapor-liquid-solid (VLS) growth of semiconductor nanowires allows doping and composition modulation along their axis and the realization of axial 1 D heterostructures. This provides additional flexibility in energy band-edge engineering along the transport direction which is difficult to attain by planar materials growth and processing techniques. We report here on the design, growth, fabrication, and characterization of asymmetric heterostructure tunnel field-effect transistors (HTFETs) based on 100% compositionally modulated Si/Ge axial NWs for high on-current operation and low ambipolar transport behavior. We discuss the optimization of band-offsets and Schottky barrier heights for high performance HTFETs and issues surrounding their experimental realization. Our HTFET devices with 10 nm PECVD SiN{sub x} gate dielectric resulted in a measured current drive exceeding 100 {mu}A/{mu}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios.

Intrinsic quantum dots in InAs nanowires

International Nuclear Information System (INIS)

Weis, Karl Martin Darius

2013-01-01

This work deals with InAs nanowire field effect transistors in back gate configuration. In such devices, quantum dots can form at low temperatures in the order of magnitude of a few Kelvin. These dots are henceforth referred to as intrinsic as they are not intentionally defined by electrodes. For the interpretation of their stability diagrams, a thorough knowledge of the structure and transport properties of the nanowires is required. Therefore, first of all, the influence of growth method and doping on the transport properties is studied at room temperature. The wires are grown by two types of metal-organic vapour phase epitaxy: a selective-area (SA-MOVPE) and an Au-catalyzed vapour-liquid-solid method (VLS-MOVPE). Transport data shows that the background doping of VLS-MOVPE wires is higher than for SA-MOVPE wires, but the variability of the transport properties is lower. The polytypism of the SA-MOVPE wires (they are composed of wurtzite and zinc blende segments) is a possible explanation for the second observation. Furthermore, it is shown that the measured transport properties significantly depend on the dielectric environment of the nanowires and on the way the electrical measurements are done (two- or four-terminal configuration). The conductivity is tunable via doping and the gate voltage. Conductivity measurements in the temperature range from 10 K to 300 K show that different transport regimes can occur (partially metallic behaviour for sufficiently high conductivity, otherwise purely semiconducting behaviour). This is attributed to different positions of the Fermi level and thus, a different effect of potential fluctuations. If conductivity and temperature are sufficiently low, the onset of Coulomb blockade is observed for semiconducting samples. It is even possible to tune the very same sample to different regimes via the gate voltage. The semiconducting behaviour observed in many samples contradicts the Thomas-Fermi theory. This is attributed to the

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

Science.gov (United States)

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

2018-05-01

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

Dual-gate operation and carrier transport in SiGe p-n junction nanowires

Science.gov (United States)

Delker, C. J.; Yoo, J. Y.; Bussmann, E.; Swartzentruber, B. S.; Harris, C. T.

2017-11-01

We investigate carrier transport in silicon-germanium nanowires with an axial p-n junction doping profile by fabricating these wires into transistors that feature separate top gates over each doping segment. By independently biasing each gate, carrier concentrations in the n- and p-side of the wire can be modulated. For these devices, which were fabricated with nickel source-drain electrical contacts, holes are the dominant charge carrier, with more favorable hole injection occurring on the p-side contact. Channel current exhibits greater sensitivity to the n-side gate, and in the reverse biased source-drain configuration, current is limited by the nickel/n-side Schottky contact.

Poly-silicon quantum-dot single-electron transistors

International Nuclear Information System (INIS)

Kang, Kwon-Chil; Lee, Joung-Eob; Lee, Jung-Han; Lee, Jong-Ho; Shin, Hyung-Cheol; Park, Byung-Gook

2012-01-01

For operation of a single-electron transistors (SETs) at room temperature, we proposed a fabrication method for a SET with a self-aligned quantum dot by using polycrystalline silicon (poly-Si). The self-aligned quantum dot is formed by the selective etching of a silicon nanowire on a planarized surface and the subsequent deposition and etch-back of poly-silicon or chemical mechanical polishing (CMP). The two tunneling barriers of the SET are fabricated by thermal oxidation. Also, to decrease the leakage current and control the gate capacitance, we deposit a hard oxide mask layer. The control gate is formed by using an electron beam and photolithography on chemical vapor deposition (CVD). Owing to the small capacitance of the narrow control gate due to the tetraethyl orthosilicate (TEOS) hard mask, we observe clear Coulomb oscillation peaks and differential trans-conductance curves at room temperature. The clear oscillation period of the fabricated SET is 2.0 V.

Silicon on ferroelectic insulator field effect transistor (SOF-FET) a new device for the next generation ultra low power circuits

Science.gov (United States)

Es-Sakhi, Azzedin D.

Field effect transistors (FETs) are the foundation for all electronic circuits and processors. These devices have progressed massively to touch its final steps in sub-nanometer level. Left and right proposals are coming to rescue this progress. Emerging nano-electronic devices (resonant tunneling devices, single-atom transistors, spin devices, Heterojunction Transistors rapid flux quantum devices, carbon nanotubes, and nanowire devices) took a vast share of current scientific research. Non-Si electronic materials like III-V heterostructure, ferroelectric, carbon nanotubes (CNTs), and other nanowire based designs are in developing stage to become the core technology of non-classical CMOS structures. FinFET present the current feasible commercial nanotechnology. The scalability and low power dissipation of this device allowed for an extension of silicon based devices. High short channel effect (SCE) immunity presents its major advantage. Multi-gate structure comes to light to improve the gate electrostatic over the channel. The new structure shows a higher performance that made it the first candidate to substitute the conventional MOSFET. The device also shows a future scalability to continue Moor's Law. Furthermore, the device is compatible with silicon fabrication process. Moreover, the ultra-low-power (ULP) design required a subthreshold slope lower than the thermionic-emission limit of 60mV/ decade (KT/q). This value was unbreakable by the new structure (SOI-FinFET). On the other hand most of the previews proposals show the ability to go beyond this limit. However, those pre-mentioned schemes have publicized a very complicated physics, design difficulties, and process non-compatibility. The objective of this research is to discuss various emerging nano-devices proposed for ultra-low-power designs and their possibilities to replace the silicon devices as the core technology in the future integrated circuit. This thesis proposes a novel design that exploits the

Blueshift of electroluminescence from single n-InP nanowire/p-Si heterojunctions due to the Burstein-Moss effect

International Nuclear Information System (INIS)

Liu, C; Dai, L; You, L P; Xu, W J; Qin, G G

2008-01-01

Single-crystalline n-type InP nanowires (NWs) with different electron concentrations were synthesized on Si substrates via the vapor phase transport method. The electrical properties of the InP nanowires were investigated by fabricating and measuring single NW field-effect transistors (FETs). Single InP NW/p + -Si heterojunctions were fabricated, and electroluminescence (EL) spectra from them were studied. It was found that both the photoluminescence (PL) spectra of the InP NWs and the EL spectra of the heterojunctions blueshift from 920 to 775 nm when the electron concentrations of the InP NWs increase from 2 x 10 17 to 1.4 x 10 19 cm -3 . The blueshifts can be attributed to the Burstein-Moss effect rather than the quantum confinement effect in the InP NWs. The large blueshifts observed in this study indicate a potential application of InP NWs in nano-multicolour displays.

Nanowire Photovoltaic Devices

Science.gov (United States)

Forbes, David

2015-01-01

Firefly Technologies, in collaboration with the Rochester Institute of Technology and the University of Wisconsin-Madison, developed synthesis methods for highly strained nanowires. Two synthesis routes resulted in successful nanowire epitaxy: direct nucleation and growth on the substrate and a novel selective-epitaxy route based on nanolithography using diblock copolymers. The indium-arsenide (InAs) nanowires are implemented in situ within the epitaxy environment-a significant innovation relative to conventional semiconductor nanowire generation using ex situ gold nanoparticles. The introduction of these nanoscale features may enable an intermediate band solar cell while simultaneously increasing the effective absorption volume that can otherwise limit short-circuit current generated by thin quantized layers. The use of nanowires for photovoltaics decouples the absorption process from the current extraction process by virtue of the high aspect ratio. While no functional solar cells resulted from this effort, considerable fundamental understanding of the nanowire epitaxy kinetics and nanopatterning process was developed. This approach could, in principle, be an enabling technology for heterointegration of dissimilar materials. The technology also is applicable to virtual substrates. Incorporating nanowires onto a recrystallized germanium/metal foil substrate would potentially solve the problem of grain boundary shunting of generated carriers by restricting the cross-sectional area of the nanowire (tens of nanometers in diameter) to sizes smaller than the recrystallized grains (0.5 to 1 micron(exp 2).

Charge Separation at Mixed-Dimensional Single and Multilayer MoS2/Silicon Nanowire Heterojunctions.

Science.gov (United States)

Henning, Alex; Sangwan, Vinod K; Bergeron, Hadallia; Balla, Itamar; Sun, Zhiyuan; Hersam, Mark C; Lauhon, Lincoln J

2018-05-16

Layered two-dimensional (2-D) semiconductors can be combined with other low-dimensional semiconductors to form nonplanar mixed-dimensional van der Waals (vdW) heterojunctions whose charge transport behavior is influenced by the heterojunction geometry, providing a new degree of freedom to engineer device functions. Toward that end, we investigated the photoresponse of Si nanowire/MoS 2 heterojunction diodes with scanning photocurrent microscopy and time-resolved photocurrent measurements. Comparison of n-Si/MoS 2 isotype heterojunctions with p-Si/MoS 2 heterojunction diodes under varying biases shows that the depletion region in the p-n heterojunction promotes exciton dissociation and carrier collection. We measure an instrument-limited response time of 1 μs, which is 10 times faster than the previously reported response times for planar Si/MoS 2 devices, highlighting the advantages of the 1-D/2-D heterojunction. Finite element simulations of device models provide a detailed understanding of how the electrostatics affect charge transport in nanowire/vdW heterojunctions and inform the design of future vdW heterojunction photodetectors and transistors.

Black Phosphorus-Zinc Oxide Nanomaterial Heterojunction for p-n Diode and Junction Field-Effect Transistor.

Science.gov (United States)

Jeon, Pyo Jin; Lee, Young Tack; Lim, June Yeong; Kim, Jin Sung; Hwang, Do Kyung; Im, Seongil

2016-02-10

Black phosphorus (BP) nanosheet is two-dimensional (2D) semiconductor with distinct band gap and attracting recent attention from researches because it has some similarity to gapless 2D semiconductor graphene in the following two aspects: single element (P) for its composition and quite high mobilities depending on its fabrication conditions. Apart from several electronic applications reported with BP nanosheet, here we report for the first time BP nanosheet-ZnO nanowire 2D-1D heterojunction applications for p-n diodes and BP-gated junction field effect transistors (JFETs) with n-ZnO channel on glass. For these nanodevices, we take advantages of the mechanical flexibility of p-type conducting of BP and van der Waals junction interface between BP and ZnO. As a result, our BP-ZnO nanodimension p-n diode displays a high ON/OFF ratio of ∼10(4) in static rectification and shows kilohertz dynamic rectification as well while ZnO nanowire channel JFET operations are nicely demonstrated by BP gate switching in both electrostatics and kilohertz dynamics.

Doped Organic Transistors.

Science.gov (United States)

Lüssem, Björn; Keum, Chang-Min; Kasemann, Daniel; Naab, Ben; Bao, Zhenan; Leo, Karl

2016-11-23

Organic field-effect transistors hold the promise of enabling low-cost and flexible electronics. Following its success in organic optoelectronics, the organic doping technology is also used increasingly in organic field-effect transistors. Doping not only increases device performance, but it also provides a way to fine-control the transistor behavior, to develop new transistor concepts, and even improve the stability of organic transistors. This Review summarizes the latest progress made in the understanding of the doping technology and its application to organic transistors. It presents the most successful doping models and an overview of the wide variety of materials used as dopants. Further, the influence of doping on charge transport in the most relevant polycrystalline organic semiconductors is reviewed, and a concise overview on the influence of doping on transistor behavior and performance is given. In particular, recent progress in the understanding of contact doping and channel doping is summarized.

Nanowire Growth for Photovoltaics

DEFF Research Database (Denmark)

Holm, Jeppe Vilstrup

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

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

Science.gov (United States)

Starko-Bowes, Ryan; Pramanik, Sandipan

2013-01-01

In recent years π-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication. A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently π-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important π-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors

Functionalised Silver Nanowire Structures

International Nuclear Information System (INIS)

Andrew, Piers; Ilie, Adelina

2007-01-01

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

Vertically integrated, three-dimensional nanowire complementary metal-oxide-semiconductor circuits.

Science.gov (United States)

Nam, SungWoo; Jiang, Xiaocheng; Xiong, Qihua; Ham, Donhee; Lieber, Charles M

2009-12-15

Three-dimensional (3D), multi-transistor-layer, integrated circuits represent an important technological pursuit promising advantages in integration density, operation speed, and power consumption compared with 2D circuits. We report fully functional, 3D integrated complementary metal-oxide-semiconductor (CMOS) circuits based on separate interconnected layers of high-mobility n-type indium arsenide (n-InAs) and p-type germanium/silicon core/shell (p-Ge/Si) nanowire (NW) field-effect transistors (FETs). The DC voltage output (V(out)) versus input (V(in)) response of vertically interconnected CMOS inverters showed sharp switching at close to the ideal value of one-half the supply voltage and, moreover, exhibited substantial DC gain of approximately 45. The gain and the rail-to-rail output switching are consistent with the large noise margin and minimal static power consumption of CMOS. Vertically interconnected, three-stage CMOS ring oscillators were also fabricated by using layer-1 InAs NW n-FETs and layer-2 Ge/Si NW p-FETs. Significantly, measurements of these circuits demonstrated stable, self-sustained oscillations with a maximum frequency of 108 MHz, which represents the highest-frequency integrated circuit based on chemically synthesized nanoscale materials. These results highlight the flexibility of bottom-up assembly of distinct nanoscale materials and suggest substantial promise for 3D integrated circuits.

Silicon nanotube field effect transistor with core-shell gate stacks for enhanced high-performance operation and area scaling benefits

KAUST Repository

Fahad, Hossain M.; Smith, Casey; Rojas, Jhonathan Prieto; Hussain, Muhammad Mustafa

2011-01-01

We introduce the concept of a silicon nanotube field effect transistor whose unique core-shell gate stacks help achieve full volume inversion by giving a surge in minority carrier concentration in the near vicinity of the ultrathin channel and at the same time rapid roll-off at the source and drain junctions constituting velocity saturation-induced higher drive current-enhanced high performance per device with efficient real estate consumption. The core-shell gate stacks also provide superior short channel effects control than classical planar metal oxide semiconductor field effect transistor (MOSFET) and gate-all-around nanowire FET. The proposed device offers the true potential to be an ideal blend for quantum ballistic transport study of device property control by bottom-up approach and high-density integration compatibility using top-down state-of-the-art complementary metal oxide semiconductor flow. © 2011 American Chemical Society.

Silicon nanotube field effect transistor with core-shell gate stacks for enhanced high-performance operation and area scaling benefits

KAUST Repository

Fahad, Hossain M.

2011-10-12

We introduce the concept of a silicon nanotube field effect transistor whose unique core-shell gate stacks help achieve full volume inversion by giving a surge in minority carrier concentration in the near vicinity of the ultrathin channel and at the same time rapid roll-off at the source and drain junctions constituting velocity saturation-induced higher drive current-enhanced high performance per device with efficient real estate consumption. The core-shell gate stacks also provide superior short channel effects control than classical planar metal oxide semiconductor field effect transistor (MOSFET) and gate-all-around nanowire FET. The proposed device offers the true potential to be an ideal blend for quantum ballistic transport study of device property control by bottom-up approach and high-density integration compatibility using top-down state-of-the-art complementary metal oxide semiconductor flow. © 2011 American Chemical Society.

Topological insulator nanowires and nanowire hetero-junctions

Science.gov (United States)

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

2014-03-01

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

Nanowire structures and electrical devices

Science.gov (United States)

Bezryadin, Alexey; Remeika, Mikas

2010-07-06

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

Organic Nanowires

DEFF Research Database (Denmark)

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

Single crystalline nanowires from fluorescing organic molecules like para-phenylenes or thiophenes are supposed to become key elements in future integrated optoelectronic devices [1]. For a sophisticated design of devices based on nanowires the basic principles of the nanowire formation have...... atomic force microscopy and from polarized far-field optical microscopy for various prototypical molecules are reproduced by electrostatic and Monte Carlo calculations. Based on the crystal structure, predictions on the growth habit from other conjugated molecules become in reach....

Fabrication of multilayer nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-06

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

Fabrication of multilayer nanowires

International Nuclear Information System (INIS)

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

2016-01-01

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

TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

Science.gov (United States)

Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan; Xie, Xi

2017-12-01

Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.

Surface state modulation through wet chemical treatment as a route to controlling the electrical properties of ZnO nanowire arrays investigated with XPS

International Nuclear Information System (INIS)

Lord, Alex M.; Maffeis, Thierry G.; Allen, Martin W.; Morgan, David; Davies, Philip R.; Jones, Daniel R.; Evans, Jonathan E.; Smith, Nathan A.; Wilks, Steve P.

2014-01-01

Highlights: • Direct measurement of the surface band bending exhibited by ZnO nanowires using monochromatic XPS. • Modulation of the surface depletion region using wet chemical treatment (EtOH, H 2 O 2 ). • The measured surface potential barrier agrees with electrical measurements of individual nanowires. • H 2 O 2 depletes the nanowire of charge carriers while EtOH donates electrons at the surface. • EtOH has the effect of restoring the surface potential barrier of oxidised nanowires. - Abstract: ZnO is a wide bandgap semiconductor that has many potential applications including solar cell electrodes, transparent thin film transistors and gas/biological sensors. Since the surfaces of ZnO materials have no amorphous or oxidised layers, they are very environmentally sensitive, making control of their semiconductor properties challenging. In particular, the electronic properties of ZnO nanostructures are dominated by surface effects while surface conduction layers have been observed in thin films and bulk crystals. Therefore, the ability to use the ZnO materials in a controlled way depends on the development of simple techniques to modulate their surface electronic properties. Here, we use monochromatic x-ray photoelectron spectroscopy (XPS) to investigate the use of different wet chemical treatments (EtOH, H 2 O 2 ) to control the electronic properties of ZnO nanowires by modulating the surface depletion region. The valence band and core level XPS spectra are used to explore the relationship between the surface chemistry of the nanowires and the surface band bending

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.

Piezotronic Effect in Polarity-Controlled GaN Nanowires.

Science.gov (United States)

Zhao, Zhenfu; Pu, Xiong; Han, Changbao; Du, Chunhua; Li, Linxuan; Jiang, Chunyan; Hu, Weiguo; Wang, Zhong Lin

2015-08-25

Using high-quality and polarity-controlled GaN nanowires (NWs), we studied the piezotronic effect in crystal orientation defined wurtzite structures. By applying a normal compressive force on c-plane GaN NWs with an atomic force microscopy tip, the Schottky barrier between the Pt tip and GaN can be effectively tuned by the piezotronic effect. In contrast, the normal compressive force cannot change the electron transport characteristics in m-plane GaN NWs whose piezoelectric polarization axis is turned in the transverse direction. This observation provided solid evidence for clarifying the difference between the piezotronic effect and the piezoresistive effect. We further demonstrated a high sensitivity of the m-plane GaN piezotronic transistor to collect the transverse force. The integration of c-plane GaN and m-plane GaN indicates an overall response to an external force in any direction.

Impact of continuing scaling on the device performance of 3D cylindrical junction-less charge trapping memory

International Nuclear Information System (INIS)

Li Xinkai; Huo Zongliang; Jin Lei; Jiang Dandan; Hong Peizhen; Xu Qiang; Tang Zhaoyun; Li Chunlong; Ye Tianchun

2015-01-01

This work presents a comprehensive analysis of 3D cylindrical junction-less charge trapping memory device performance regarding continuous scaling of the structure dimensions. The key device performance, such as program/erase speed, vertical charge loss, and lateral charge migration under high temperature are intensively studied using the Sentaurus 3D device simulator. Although scaling of channel radius is beneficial for operation speed improvement, it leads to a retention challenge due to vertical leakage, especially enhanced charge loss through TPO. Scaling of gate length not only decreases the program/erase speed but also leads to worse lateral charge migration. Scaling of spacer length is critical for the interference of adjacent cells and should be carefully optimized according to specific cell operation conditions. The gate stack shape is also found to be an important factor affecting the lateral charge migration. Our results provide guidance for high density and high reliability 3D CTM integration. (paper)

Electrochemically grown rough-textured nanowires

International Nuclear Information System (INIS)

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

2010-01-01

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

Unijunction transistors

International Nuclear Information System (INIS)

1981-01-01

The electrical characteristics of unijunction transistors can be modified by irradiation with electron beams in excess of 400 KeV and at a dose rate of 10 13 to 10 16 e/cm 2 . Examples are given of the effect of exposing the emitter-base junctions of transistors to such lattice defect causing radiation for a time sufficient to change the valley current of the transistor. (U.K.)

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

Directory of Open Access Journals (Sweden)

U Hyeok Choi

2017-10-01

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

p-type ZnS:N nanowires: Low-temperature solvothermal doping and optoelectronic properties

International Nuclear Information System (INIS)

Wang, Ming-Zheng; Xie, Wei-Jie; Hu, Han; Yu, Yong-Qiang; Wu, Chun-Yan; Wang, Li; Luo, Lin-Bao

2013-01-01

Nitrogen doped p-type ZnS nanowires (NWs) were realized using thermal decomposition of triethylamine at a mild temperature. Field-effect transistors made from individual ZnS:N NWs revealed typical p-type conductivity behavior, with a hole mobility of 3.41 cm 2 V −1 s −1 and a hole concentration of 1.67 × 10 17  cm −3 , respectively. Further analysis found that the ZnS:N NW is sensitive to UV light irradiation with high responsivity, photoconductive gain, and good spectral selectivity. The totality of this study suggests that the solvothermal doping method is highly feasible to dope one dimensional semiconductor nanostructures for optoelectronic devices application

Attofarad resolution capacitance-voltage measurement of nanometer scale field effect transistors utilizing ambient noise

International Nuclear Information System (INIS)

Gokirmak, Ali; Inaltekin, Hazer; Tiwari, Sandip

2009-01-01

A high resolution capacitance-voltage (C-V) characterization technique, enabling direct measurement of electronic properties at the nanoscale in devices such as nanowire field effect transistors (FETs) through the use of random fluctuations, is described. The minimum noise level required for achieving sub-aF (10 -18 F) resolution, the leveraging of stochastic resonance, and the effect of higher levels of noise are illustrated through simulations. The non-linear ΔC gate-source/drain -V gate response of FETs is utilized to determine the inversion layer capacitance (C inv ) and carrier mobility. The technique is demonstrated by extracting the carrier concentration and effective electron mobility in a nanoscale Si FET with C inv = 60 aF.

Light-effect transistor (LET with multiple independent gating controls for optical logic gates and optical amplification

Directory of Open Access Journals (Sweden)

Jason eMarmon

2016-03-01

Full Text Available Modern electronics are developing electronic-optical integrated circuits, while their electronic backbone, e.g. field-effect transistors (FETs, remains the same. However, further FET down scaling is facing physical and technical challenges. A light-effect transistor (LET offers electronic-optical hybridization at the component level, which can continue Moore’s law to quantum region without requiring a FET’s fabrication complexity, e.g. physical gate and doping, by employing optical gating and photoconductivity. Multiple independent gates are therefore readily realized to achieve unique functionalities without increasing chip space. Here we report LET device characteristics and novel digital and analog applications, such as optical logic gates and optical amplification. Prototype CdSe-nanowire-based LETs show output and transfer characteristics resembling advanced FETs, e.g. on/off ratios up to ~1.0x106 with a source-drain voltage of ~1.43 V, gate-power of ~260 nW, and subthreshold swing of ~0.3 nW/decade (excluding losses. Our work offers new electronic-optical integration strategies and electronic and optical computing approaches.

Synthesis, microstructural characterization and optical properties of CuO nanorods and nanowires obtained by aerosol assisted CVD

International Nuclear Information System (INIS)

Lugo-Ruelas, M.; Amézaga-Madrid, P.; Esquivel-Pereyra, O.; Antúnez-Flores, W.; Pizá-Ruiz, P.; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.

2015-01-01

Highlights: • Nanorods and nanowires of CuO were successfully synthesized by AACVD technique. • The carrier gas velocity was a determinant factor for the growth of nanorods or nanowires. • The increase of deposition time generates the reduction in the evenness and distribution density. • The crystalline phase of nanorods and nanowires was monoclinic tenorite. - Abstract: Copper oxide is a particularly interesting material because it presents photovoltaic, electrochemical and catalytic properties. Its unique properties are very important in the area of nanotechnology and may be an advantage because these nanomaterials can be applied in the design and manufacture of nanosensors, photocatalysis area, nanolasers switches and transistors. Nowadays one-dimensional nanostructures as nanorods, nanowires, etc., have generated a great importance and have received considerable attention and study due to their unique physical and chemical properties. In this work we report the synthesis, microstructural characterization and optical properties of CuO nanorods and nanowires grown by aerosol assisted chemical vapor deposition onto a CuO, ZnO and TiO 2 thin film covered and bare borosilicate glass substrate. Concentration of the precursor solution and carrier gas flux were previously optimized and fixed at 0.1 mol dm −3 and 5 L min −1 , respectively. Other deposition parameters such as substrate temperature, as well the carrier gas velocity and deposition time were varied from 623 to 973 K, 0.88 to 1.77 m s −1 and 11 to 16 min, respectively. Their influence on the morphology, microstructure and optical properties of the nanorods and nanowires were analyzed. The crystalline structure of the materials was characterized by grazing incidence X-ray diffraction; results indicate the presence of the tenorite phase. Surface morphology and microstructure were studied by field emission scanning electron microscopy, and high resolution transmission electron microscopy. Optical

From nanodiamond to nanowires.

Energy Technology Data Exchange (ETDEWEB)

Barnard, A.; Materials Science Division

2005-01-01

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

Ambient template synthesis of multiferroic MnWO4 nanowires and nanowire arrays

International Nuclear Information System (INIS)

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

2008-01-01

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

Porous Silicon Nanowires

Science.gov (United States)

Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

2011-01-01

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

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

Science.gov (United States)

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

2018-05-09

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

An optimized junctionless GAA MOSFET design based on multi-objective computation for high-performance ultra-low power devices

International Nuclear Information System (INIS)

Bendib, T.; Djeffal, F.; Meguellati, M.

2014-01-01

An analytical investigation has been proposed to study the subthreshold behavior of junctionless gates all around (JLGAA) MOSFET for nanoscale CMOS analog applications. Based on 2-D analytical analysis, a new subthreshold swing model for short-channel JLGAA MOSFETs is developed. The analysis has been used to calculate the subthreshold swing and to compare the performance of the investigated design and conventional GAA MOSFET, where the comparison of device architectures shows that the JLGAA MOSFET exhibits a superior performance with respect to the conventional inversion-mode GAA MOSFET in terms of the fabrication process and electrical behavior in the subthreshold domain. The analytical models have been validated by 2-D numerical simulations. The proposed analytical models are used to formulate the objectives functions. The overall objective function is formulated by means of a weighted sum approach to search the optimal electrical and dimensional device parameters in order to obtain the better scaling capability and the electrical performance of the device for ultra-low power applications. (semiconductor devices)

Quantum optics with nanowires (Conference Presentation)

Science.gov (United States)

Zwiller, Val

2017-02-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-16

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

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

Science.gov (United States)

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

2016-05-01

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

Design and synthesis of diverse functional kinked nanowire structures for nanoelectronic bioprobes.

Science.gov (United States)

Xu, Lin; Jiang, Zhe; Qing, Quan; Mai, Liqiang; Zhang, Qingjie; Lieber, Charles M

2013-02-13

Functional kinked nanowires (KNWs) represent a new class of nanowire building blocks, in which functional devices, for example, nanoscale field-effect transistors (nanoFETs), are encoded in geometrically controlled nanowire superstructures during synthesis. The bottom-up control of both structure and function of KNWs enables construction of spatially isolated point-like nanoelectronic probes that are especially useful for monitoring biological systems where finely tuned feature size and structure are highly desired. Here we present three new types of functional KNWs including (1) the zero-degree KNW structures with two parallel heavily doped arms of U-shaped structures with a nanoFET at the tip of the "U", (2) series multiplexed functional KNW integrating multi-nanoFETs along the arm and at the tips of V-shaped structures, and (3) parallel multiplexed KNWs integrating nanoFETs at the two tips of W-shaped structures. First, U-shaped KNWs were synthesized with separations as small as 650 nm between the parallel arms and used to fabricate three-dimensional nanoFET probes at least 3 times smaller than previous V-shaped designs. In addition, multiple nanoFETs were encoded during synthesis in one of the arms/tip of V-shaped and distinct arms/tips of W-shaped KNWs. These new multiplexed KNW structures were structurally verified by optical and electron microscopy of dopant-selective etched samples and electrically characterized using scanning gate microscopy and transport measurements. The facile design and bottom-up synthesis of these diverse functional KNWs provides a growing toolbox of building blocks for fabricating highly compact and multiplexed three-dimensional nanoprobes for applications in life sciences, including intracellular and deep tissue/cell recordings.

Artificial neural systems using memristive synapses and nano-crystalline silicon thin-film transistors

Science.gov (United States)

Cantley, Kurtis D.

Future computer systems will not rely solely on digital processing of inputs from well-defined data sets. They will also be required to perform various computational tasks using large sets of ill-defined information from the complex environment around them. The most efficient processor of this type of information known today is the human brain. Using a large number of primitive elements (˜1010 neurons in the neocortex) with high parallel connectivity (each neuron has ˜104 synapses), brains have the remarkable ability to recognize and classify patterns, predict outcomes, and learn from and adapt to incredibly diverse sets of problems. A reasonable goal in the push to increase processing power of electronic systems would thus be to implement artificial neural networks in hardware that are compatible with today's digital processors. This work focuses on the feasibility of utilizing non-crystalline silicon devices in neuromorphic electronics. Hydrogenated amorphous silicon (a-Si:H) nanowire transistors with Schottky barrier source/drain junctions, as well as a-Si:H/Ag resistive switches are fabricated and characterized. In the transistors, it is found that the on-current scales linearly with the effective width W eff of the channel nanowire array down to at least 20 nm. The solid-state electrolyte resistive switches (memristors) are shown to exhibit the proper current-voltage hysteresis. SPICE models of similar devices are subsequently developed to investigate their performance in neural circuits. The resulting SPICE simulations demonstrate spiking properties and synaptic learning rules that are incredibly similar to those in biology. Specifically, the neuron circuits can be designed to mimic the firing characteristics of real neurons, and Hebbian learning rules are investigated. Finally, some applications are presented, including associative learning analogous to the classical conditioning experiments originally performed by Pavlov, and frequency and pattern

A silicon nanowire heater and thermometer

Science.gov (United States)

Zhao, Xingyan; Dan, Yaping

2017-07-01

In the thermal conductivity measurements of thermoelectric materials, heaters and thermometers made of the same semiconducting materials under test, forming a homogeneous system, will significantly simplify fabrication and integration. In this work, we demonstrate a high-performance heater and thermometer made of single silicon nanowires (SiNWs). The SiNWs are patterned out of a silicon-on-insulator wafer by CMOS-compatible fabrication processes. The electronic properties of the nanowires are characterized by four-probe and low temperature Hall effect measurements. The I-V curves of the nanowires are linear at small voltage bias. The temperature dependence of the nanowire resistance allows the nanowire to be used as a highly sensitive thermometer. At high voltage bias, the I-V curves of the nanowire become nonlinear due to the effect of Joule heating. The temperature of the nanowire heater can be accurately monitored by the nanowire itself as a thermometer.

Intrinsic Ge nanowire nonvolatile memory based on a simple core–shell structure

International Nuclear Information System (INIS)

Chen, Wen-Hua; Liu, Chang-Hai; Li, Qin-Liang; Sun, Qi-Jun; Liu, Jie; Gao, Xu; Sun, Xuhui; Wang, Sui-Dong

2014-01-01

Intrinsic Ge nanowires (NWs) with a Ge core covered by a thick Ge oxide shell are utilized to achieve nanoscale field-effect transistor nonvolatile memories, which show a large memory window and a high ON/OFF ratio with good retention. The retainable surface charge trapping is considered to be responsible for the memory effect, and the Ge oxide shell plays a key role as the insulating tunneling dielectric which must be thick enough to prevent stored surface charges from leaking out. Annealing the device in air is demonstrated to be a simple and effective way to attain thick Ge oxide on the Ge NW surface, and the Ge-NW-based memory corresponding to thick Ge oxide exhibits a much better retention capability compared with the case of thin Ge oxide. (paper)

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

Science.gov (United States)

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

2017-08-01

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

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

Directory of Open Access Journals (Sweden)

M. Marus

2018-03-01

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

Vertical nanowire architectures

DEFF Research Database (Denmark)

Vlad, A.; Mátéfl-Tempfli, M.; Piraux, L.

2010-01-01

Nanowires and statistics: A statistical process for reading ultradense arrays of nanostructured materials is presented (see image). The experimental realization is achieved through selective nanowire growth using porous alumina templates. The statistical patterning approach is found to provide ri...

Diameter-dependent coloration of silver nanowires

International Nuclear Information System (INIS)

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

2011-01-01

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

Copper atomic-scale transistors.

Science.gov (United States)

Xie, Fangqing; Kavalenka, Maryna N; Röger, Moritz; Albrecht, Daniel; Hölscher, Hendrik; Leuthold, Jürgen; Schimmel, Thomas

2017-01-01

We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO 4 + H 2 SO 4 ) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and -170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes ( U bias ) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1 G 0 ( G 0 = 2e 2 /h; with e being the electron charge, and h being Planck's constant) or 2 G 0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors.

Fe nanoparticle tailored poly(N-methyl pyrrole) nanowire matrix: a CHEMFET study from the perspective of discrimination among electron donating analytes

International Nuclear Information System (INIS)

Datta, K; Rushi, A; Shirsat, M; Mulchandani, A; Ghosh, P

2015-01-01

Back-gated chemically sensitive field effect transistor (CHEMFET) platforms have been developed with electrochemically synthesized poly(N-methyl pyrrole) nanowires by a templateless route. The nanowire matrix has been tailored with Fe nanoparticles to probe their effect in enhancing the sensing capabilities of the nanowire platform, and further to see if the inculcation of Fe nanoparticles is helpful to enhance the screening capability of the sensor among electron donating analytes. A noticeable difference in the sensing behaviour of the CHEMFET sensor was observed when it was exposed to three different analytes—ammonia, phosphine and carbon monoxide. FET transfer characteristics were instrumental in the corroboration of the experimental validations. The observations have been rationalized considering the simultaneous modulation of the work functions of Fe and polymeric material. The real time behaviour of the sensor shows that the sensor platform is readily capable of sensing the validated analytes at a ppb level of concentration with good response and recovery behaviour. The best response could be observed for ammonia with an Fe nanoparticle tailored polymeric matrix, with a sensitivity of ∼31.58% and excellent linearity (R 2 = 0.985) in a concentration window of 0.05 ppm to 1 ppm. (paper)

A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor.

Science.gov (United States)

Lee, Jieun; Jang, Jaeman; Choi, Bongsik; Yoon, Jinsu; Kim, Jee-Yeon; Choi, Yang-Kyu; Kim, Dong Myong; Kim, Dae Hwan; Choi, Sung-Jin

2015-07-21

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 advantage of high density and low noise performance. The biosensor shows a current response of 5.74 decades per pH for pH detection, which is 2.5 × 10(5) times larger than that of a single SiNW sensor. In addition, we demonstrate charged polymer detection using the biosensor, with a high current change of 4.5 × 10(5) with a 500 nM concentration of poly(allylamine hydrochloride). In addition, we demonstrate a wide dynamic range can be obtained by adjusting the liquid gate voltage. We expect that this biosensor will be advantageous and practical for biosensor applications which requires lower noise, high speed, and high density.

Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs

Directory of Open Access Journals (Sweden)

Hong Yu

2009-04-01

Full Text Available In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors.

Methods for synthesizing metal oxide nanowires

Science.gov (United States)

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

2016-08-09

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

Electron Transport Properties of Ge nanowires

Science.gov (United States)

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

2003-03-01

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

EDITORIAL: Nanowires for energy Nanowires for energy

Science.gov (United States)

LaPierre, Ray; Sunkara, Mahendra

2012-05-01

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

Electrically Injected UV-Visible Nanowire Lasers

Energy Technology Data Exchange (ETDEWEB)

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

2015-09-01

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

Nanowire-decorated microscale metallic electrodes

DEFF Research Database (Denmark)

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

2008-01-01

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

Approaching the Hole Mobility Limit of GaSb Nanowires.

Science.gov (United States)

Yang, Zai-xing; Yip, SenPo; Li, Dapan; Han, Ning; Dong, Guofa; Liang, Xiaoguang; Shu, Lei; Hung, Tak Fu; Mo, Xiaoliang; Ho, Johnny C

2015-09-22

In recent years, high-mobility GaSb nanowires have received tremendous attention for high-performance p-type transistors; however, due to the difficulty in achieving thin and uniform nanowires (NWs), there is limited report until now addressing their diameter-dependent properties and their hole mobility limit in this important one-dimensional material system, where all these are essential information for the deployment of GaSb NWs in various applications. Here, by employing the newly developed surfactant-assisted chemical vapor deposition, high-quality and uniform GaSb NWs with controllable diameters, spanning from 16 to 70 nm, are successfully prepared, enabling the direct assessment of their growth orientation and hole mobility as a function of diameter while elucidating the role of sulfur surfactant and the interplay between surface and interface energies of NWs on their electrical properties. The sulfur passivation is found to efficiently stabilize the high-energy NW sidewalls of (111) and (311) in order to yield the thin NWs (i.e., 40 nm in diameters) would grow along the most energy-favorable close-packed planes with the orientation of ⟨111⟩, supported by the approximate atomic models. Importantly, through the reliable control of sulfur passivation, growth orientation and surface roughness, GaSb NWs with the peak hole mobility of ∼400 cm(2)V s(-1) for the diameter of 48 nm, approaching the theoretical limit under the hole concentration of ∼2.2 × 10(18) cm(-3), can be achieved for the first time. All these indicate their promising potency for utilizations in different technological domains.

A Steep-Slope Transistor Combining Phase-Change and Band-to-Band-Tunneling to Achieve a sub-Unity Body Factor.

Science.gov (United States)

Vitale, Wolfgang A; Casu, Emanuele A; Biswas, Arnab; Rosca, Teodor; Alper, Cem; Krammer, Anna; Luong, Gia V; Zhao, Qing-T; Mantl, Siegfried; Schüler, Andreas; Ionescu, A M

2017-03-23

Steep-slope transistors allow to scale down the supply voltage and the energy per computed bit of information as compared to conventional field-effect transistors (FETs), due to their sub-60 mV/decade subthreshold swing at room temperature. Currently pursued approaches to achieve such a subthermionic subthreshold swing consist in alternative carrier injection mechanisms, like quantum mechanical band-to-band tunneling (BTBT) in Tunnel FETs or abrupt phase-change in metal-insulator transition (MIT) devices. The strengths of the BTBT and MIT have been combined in a hybrid device architecture called phase-change tunnel FET (PC-TFET), in which the abrupt MIT in vanadium dioxide (VO 2 ) lowers the subthreshold swing of strained-silicon nanowire TFETs. In this work, we demonstrate that the principle underlying the low swing in the PC-TFET relates to a sub-unity body factor achieved by an internal differential gate voltage amplification. We study the effect of temperature on the switching ratio and the swing of the PC-TFET, reporting values as low as 4.0 mV/decade at 25 °C, 7.8 mV/decade at 45 °C. We discuss how the unique characteristics of the PC-TFET open new perspectives, beyond FETs and other steep-slope transistors, for low power electronics, analog circuits and neuromorphic computing.

Superconducting transistor

International Nuclear Information System (INIS)

Gray, K.E.

1978-01-01

A three film superconducting tunneling device, analogous to a semiconductor transistor, is presented, including a theoretical description and experimental results showing a current gain of four. Much larger current gains are shown to be feasible. Such a development is particularly interesting because of its novelty and the striking analogies with the semiconductor junction transistor

Silicon heterojunction transistor

International Nuclear Information System (INIS)

Matsushita, T.; Oh-uchi, N.; Hayashi, H.; Yamoto, H.

1979-01-01

SIPOS (Semi-insulating polycrystalline silicon) which is used as a surface passivation layer for highly reliable silicon devices constitutes a good heterojunction for silicon. P- or B-doped SIPOS has been used as the emitter material of a heterojunction transistor with the base and collector of silicon. An npn SIPOS-Si heterojunction transistor showing 50 times the current gain of an npn silicon homojunction transistor has been realized by high-temperature treatments in nitrogen and low-temperature annealing in hydrogen or forming gas

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Platinum boride nanowires: Synthesis and characterization

International Nuclear Information System (INIS)

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

2012-01-01

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

Accelerating the life of transistors

International Nuclear Information System (INIS)

Qi Haochun; Lü Changzhi; Zhang Xiaoling; Xie Xuesong

2013-01-01

Choosing small and medium power switching transistors of the NPN type in a 3DK set as the study object, the test of accelerating life is conducted in constant temperature and humidity, and then the data are statistically analyzed with software developed by ourselves. According to degradations of such sensitive parameters as the reverse leakage current of transistors, the lifetime order of transistors is about more than 10 4 at 100 °C and 100% relative humidity (RH) conditions. By corrosion fracture of transistor outer leads and other failure modes, with the failure truncated testing, the average lifetime rank of transistors in different distributions is extrapolated about 10 3 . Failure mechanism analyses of degradation of electrical parameters, outer lead fracture and other reasons that affect transistor lifetime are conducted. The findings show that the impact of external stress of outer leads on transistor reliability is more serious than that of parameter degradation. (semiconductor devices)

GaN Nanowire Devices: Fabrication and Characterization

Science.gov (United States)

Scott, Reum

The development of microelectronics in the last 25 years has been characterized by an exponential increase of the bit density in integrated circuits (ICs) with time. Scaling solid-state devices improves cost, performance, and power; as such, it is of particular interest for companies, who gain a market advantage with the latest technology. As a result, the microelectronics industry has driven transistor feature size scaling from 10 μm to ~30 nm during the past 40 years. This trend has persisted for 40 years due to optimization, new processing techniques, device structures, and materials. But when noting processor speeds from the 1970's to 2009 and then again in 2010, the implication would be that the trend has ceased. To address the challenge of shrinking the integrated circuit (IC), current research is centered on identifying new materials and devices that can supplement and/or potentially supplant it. Bottom-up methods tailor nanoscale building blocks---atoms, molecules, quantum dots, and nanowires (NWs)---to be used to overcome these limitations. The Group IIIA nitrides (InN, AlN, and GaN) possess appealing properties such as a direct band gap spanning the whole solar spectrum, high saturation velocity, and high breakdown electric field. As a result nanostructures and nanodevices made from GaN and related nitrides are suitable candidates for efficient nanoscale UV/ visible light emitters, detectors, and gas sensors. To produce devices with such small structures new fabrication methods must be implemented. Devices composed of GaN nanowires were fabricated using photolithography and electron beam lithography. The IV characteristics of these devices were noted under different illuminations and the current tripled from 4.8*10-7 A to 1.59*10 -6 A under UV light which persisted for at least 5hrs.

PREFACE: Synthesis and integration of nanowires

Science.gov (United States)

Samuelson, L.

2006-06-01

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

Electrospinning synthesis of superconducting BSCCO nanowires

International Nuclear Information System (INIS)

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

2013-01-01

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

Micromagnetic simulations of cylindrical magnetic nanowires

KAUST Repository

Ivanov, Yurii P.

2015-05-27

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

Magnetostatic Interaction in Fe-Co Nanowires

Directory of Open Access Journals (Sweden)

Laura Elbaile

2012-01-01

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

Resistance Fluctuations in GaAs Nanowire Grids

Directory of Open Access Journals (Sweden)

Ivan Marasović

2014-01-01

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

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Silicon nanowire hybrid photovoltaics

KAUST Repository

Garnett, Erik C.

2010-06-01

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

Silicon nanowire hybrid photovoltaics

KAUST Repository

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

2010-01-01

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

Analog performance of vertical nanowire TFETs as a function of temperature and transport mechanism

Science.gov (United States)

Martino, Marcio Dalla Valle; Neves, Felipe; Ghedini Der Agopian, Paula; Martino, João Antonio; Vandooren, Anne; Rooyackers, Rita; Simoen, Eddy; Thean, Aaron; Claeys, Cor

2015-10-01

The goal of this work is to study the analog performance of tunnel field effect transistors (TFETs) and its susceptibility to temperature variation and to different dominant transport mechanisms. The experimental input characteristic of nanowire TFETs with different source compositions (100% Si and Si1-xGex) has been presented, leading to the extraction of the Activation Energy for each bias condition. These first results have been connected to the prevailing transport mechanism for each configuration, namely band-to-band tunneling (BTBT) or trap assisted tunneling (TAT). Afterward, this work analyzes the analog behavior, with the intrinsic voltage gain calculated in terms of Early voltage, transistor efficiency, transconductance and output conductance. Comparing the results for devices with different source compositions, it is interesting to note how the analog trends vary depending on the source characteristics and the prevailing transport mechanisms. This behavior results in a different suitability analysis depending on the working temperature. In other words, devices with full-Silicon source and non-abrupt junction profile present the worst intrinsic voltage gain at room temperature, but the best results for high temperatures. This was possible since, among the 4 studied devices, this configuration was the only one with a positive intrinsic voltage gain dependence on the temperature variation.

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

Science.gov (United States)

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

2012-01-01

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

Nanowire sensors and arrays for chemical/biomolecule detection

Science.gov (United States)

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

2005-01-01

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

Structural and tunneling properties of Si nanowires

KAUST Repository

Montes Muñoz, Enrique

2013-12-06

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

Structural and tunneling properties of Si nanowires

KAUST Repository

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

2013-01-01

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

High-performance vertical organic transistors.

Science.gov (United States)

Kleemann, Hans; Günther, Alrun A; Leo, Karl; Lüssem, Björn

2013-11-11

Vertical organic thin-film transistors (VOTFTs) are promising devices to overcome the transconductance and cut-off frequency restrictions of horizontal organic thin-film transistors. The basic physical mechanisms of VOTFT operation, however, are not well understood and VOTFTs often require complex patterning techniques using self-assembly processes which impedes a future large-area production. In this contribution, high-performance vertical organic transistors comprising pentacene for p-type operation and C60 for n-type operation are presented. The static current-voltage behavior as well as the fundamental scaling laws of such transistors are studied, disclosing a remarkable transistor operation with a behavior limited by injection of charge carriers. The transistors are manufactured by photolithography, in contrast to other VOTFT concepts using self-assembled source electrodes. Fluorinated photoresist and solvent compounds allow for photolithographical patterning directly and strongly onto the organic materials, simplifying the fabrication protocol and making VOTFTs a prospective candidate for future high-performance applications of organic transistors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Interactions between semiconductor nanowires and living cells.

Science.gov (United States)

Prinz, Christelle N

2015-06-17

Semiconductor nanowires are increasingly used for biological applications and their small dimensions make them a promising tool for sensing and manipulating cells with minimal perturbation. In order to interface cells with nanowires in a controlled fashion, it is essential to understand the interactions between nanowires and living cells. The present paper reviews current progress in the understanding of these interactions, with knowledge gathered from studies where living cells were interfaced with vertical nanowire arrays. The effect of nanowires on cells is reported in terms of viability, cell-nanowire interface morphology, cell behavior, changes in gene expression as well as cellular stress markers. Unexplored issues and unanswered questions are discussed.

Electrodeposition of rhenium-tin nanowires

International Nuclear Information System (INIS)

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

2011-01-01

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

Logarithmic current-measuring transistor circuits

DEFF Research Database (Denmark)

Højberg, Kristian Søe

1967-01-01

Describes two transistorized circuits for the logarithmic measurement of small currents suitable for nuclear reactor instrumentation. The logarithmic element is applied in the feedback path of an amplifier, and only one dual transistor is used as logarithmic diode and temperature compensating...... transistor. A simple one-amplifier circuit is compared with a two-amplifier system. The circuits presented have been developed in connexion with an amplifier using a dual m.o.s. transistor input stage with diode-protected gates....

Shootthrough fault protection system for bipolar transistors in a voltage source transistor inverter

International Nuclear Information System (INIS)

Wirth, W.F.

1982-01-01

Faulted bipolar transistors in a voltage source transistor inverter are protected against shootthrough fault current, from the filter capacitor of the d-c voltage source which drives the inverter over the d-c bus, by interposing a small choke in series with the filter capacitor to limit the rate of rise of that fault current while at the same time causing the d-c bus voltage to instantly drop to essentially zero volts at the beginning of a shootthrough fault. In this way, the load lines of the faulted transistors are effectively shaped so that they do not enter the second breakdown area, thereby preventing second breakdown destruction of the transistors

Gold nanowires and the effect of impurities

Directory of Open Access Journals (Sweden)

Novaes Frederico

2006-01-01

Full Text Available AbstractMetal nanowires and in particular gold nanowires have received a great deal of attention in the past few years. Experiments on gold nanowires have prompted theory and simulation to help answer questions posed by these studies. Here we present results of computer simulations for the formation, evolution and breaking of very thin Au nanowires. We also discuss the influence of contaminants, such as atoms and small molecules, and their effect on the structural and mechanical properties of these nanowires.

Electric Conductivity of Phosphorus Nanowires

International Nuclear Information System (INIS)

Jing-Xiang, Zhang; Hui, Li; Xue-Qing, Zhang; Kim-Meow, Liew

2009-01-01

We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

Study of spin dynamics and damping on the magnetic nanowire arrays with various nanowire widths

Energy Technology Data Exchange (ETDEWEB)

Cho, Jaehun [Department of Physics, Inha University, Incheon, 402-751 (Korea, Republic of); Fujii, Yuya; Konioshi, Katsunori [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Yoon, Jungbum [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Kim, Nam-Hui; Jung, Jinyong [Department of Physics, Inha University, Incheon, 402-751 (Korea, Republic of); Miwa, Shinji [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Jung, Myung-Hwa [Department of Physics, Sogang University, Seoul, 121-742 (Korea, Republic of); Suzuki, Yoshishige [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); You, Chun-Yeol, E-mail: cyyou@inha.ac.kr [Department of Physics, Inha University, Incheon, 402-751 (Korea, Republic of)

2016-07-01

We investigate the spin dynamics including Gilbert damping in the ferromagnetic nanowire arrays. We have measured the ferromagnetic resonance of ferromagnetic nanowire arrays using vector-network analyzer ferromagnetic resonance (VNA-FMR) and analyzed the results with the micromagnetic simulations. We find excellent agreement between the experimental VNA-FMR spectra and micromagnetic simulations result for various applied magnetic fields. We find that the same tendency of the demagnetization factor for longitudinal and transverse conditions, N{sub z} (N{sub y}) increases (decreases) as increasing the nanowire width in the micromagnetic simulations while N{sub x} is almost zero value in transverse case. We also find that the Gilbert damping constant increases from 0.018 to 0.051 as the increasing nanowire width for the transverse case, while it is almost constant as 0.021 for the longitudinal case. - Highlights: • We investigate the spin dynamic properties in the ferromagnetic nanowire arrays. • The demagnetization factors have similar tendency with the prism geometry results. • The Gilbert damping constant is increased from 0.018 to 0.051 as the increasing nanowire width for the transverse. • The Gilbert damping constant is almost constant as 0.021 for the longitudinal case.

A High-Voltage Level Tolerant Transistor Circuit

NARCIS (Netherlands)

Annema, Anne J.; Geelen, Godefridus Johannes Gertrudis Maria

2001-01-01

A high-voltage level tolerant transistor circuit, comprising a plurality of cascoded transistors, including a first transistor (T1) operatively connected to a high-voltage level node (3) and a second transistor (T2) operatively connected to a low-voltage level node (2). The first transistor (T1)

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...

Diode, transistor & fet circuits manual

CERN Document Server

Marston, R M

2013-01-01

Diode, Transistor and FET Circuits Manual is a handbook of circuits based on discrete semiconductor components such as diodes, transistors, and FETS. The book also includes diagrams and practical circuits. The book describes basic and special diode characteristics, heat wave-rectifier circuits, transformers, filter capacitors, and rectifier ratings. The text also presents practical applications of associated devices, for example, zeners, varicaps, photodiodes, or LEDs, as well as it describes bipolar transistor characteristics. The transistor can be used in three basic amplifier configuration

Vertical organic transistors

International Nuclear Information System (INIS)

Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

2015-01-01

Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted. (topical review)

Vertical organic transistors.

Science.gov (United States)

Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

2015-11-11

Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted.

Vertically aligned nanowires from boron-doped diamond.

Science.gov (United States)

Yang, Nianjun; Uetsuka, Hiroshi; Osawa, Eiji; Nebel, Christoph E

2008-11-01

Vertically aligned diamond nanowires with controlled geometrical properties like length and distance between wires were fabricated by use of nanodiamond particles as a hard mask and by use of reactive ion etching. The surface structure, electronic properties, and electrochemical functionalization of diamond nanowires were characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) as well as electrochemical techniques. AFM and STM experiments show that diamond nanowire etched for 10 s have wire-typed structures with 3-10 nm in length and with typically 11 nm spacing in between. The electrode active area of diamond nanowires is enhanced by a factor of 2. The functionalization of nanowire tips with nitrophenyl molecules is characterized by STM on clean and on nitrophenyl molecule-modified diamond nanowires. Tip-modified diamond nanowires are promising with respect to biosensor applications where controlled biomolecule bonding is required to improve chemical stability and sensing significantly.

Nanowire failure: long = brittle and short = ductile.

Science.gov (United States)

Wu, Zhaoxuan; Zhang, Yong-Wei; Jhon, Mark H; Gao, Huajian; Srolovitz, David J

2012-02-08

Experimental studies of the tensile behavior of metallic nanowires show a wide range of failure modes, ranging from ductile necking to brittle/localized shear failure-often in the same diameter wires. We performed large-scale molecular dynamics simulations of copper nanowires with a range of nanowire lengths and provide unequivocal evidence for a transition in nanowire failure mode with change in nanowire length. Short nanowires fail via a ductile mode with serrated stress-strain curves, while long wires exhibit extreme shear localization and abrupt failure. We developed a simple model for predicting the critical nanowire length for this failure mode transition and showed that it is in excellent agreement with both the simulation results and the extant experimental data. The present results provide a new paradigm for the design of nanoscale mechanical systems that demarcates graceful and catastrophic failure. © 2012 American Chemical Society

Ballistic superconductivity in semiconductor nanowires

Science.gov (United States)

Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P.; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K.; van Veen, Jasper; de Moor, Michiel W. A.; Bommer, Jouri D. S.; van Woerkom, David J.; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P.A.M.; Quintero-Pérez, Marina; Cassidy, Maja C.; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo P.

2017-01-01

Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices. PMID:28681843

Long Silver Nanowires Synthesis by Pulsed Electrodeposition

Directory of Open Access Journals (Sweden)

M.R. Batevandi

2015-09-01

Full Text Available Silver nanowires were pulse electrodeposited into nanopore anodic alumina oxide templates. The effects of continuous and pulse electrodeposition waveform on the microstructure properties of the nanowire arrays were studied. It is seen that the microstructure of nanowire is depend to pulse condition. The off time duration of pulse waveform enables to control the growth direction of Ag nanowires.

On theory of single-molecule transistor

International Nuclear Information System (INIS)

Tran Tien Phuc

2009-01-01

The results of the study on single-molecule transistor are mainly investigated in this paper. The structure of constructed single-molecule transistor is similar to a conventional MOSFET. The conductive channel of the transistors is a single-molecule of halogenated benzene derivatives. The chemical simulation software CAChe was used to design and implement for the essential parameter of the molecules utilized as the conductive channel. The GUI of Matlab has been built to design its graphical interface, calculate and plot the output I-V characteristic curves for the transistor. The influence of temperature, length and width of the conductive channel, and gate voltage is considered. As a result, the simulated curves are similar to the traditional MOSFET's. The operating temperature range of the transistors is wider compared with silicon semiconductors. The supply voltage for transistors is only about 1 V. The size of transistors in this research is several nanometers.

Preparation and characterization of CuO nanowire arrays

International Nuclear Information System (INIS)

Yu Dongliang; Ge Chuannan; Du Youwei

2009-01-01

CuO nanowire arrays were prepared by oxidation of copper nanowires embedded in anodic aluminum oxide (AAO) membranes. The AAO was fabricated in an oxalic acid at a constant voltage. Copper nanowires were formed in the nanopores of the AAO membranes in an electrochemical deposition process. The oxidized copper nanowires at different temperatures were studied. X-ray diffraction patterns confirmed the formation of a CuO phase after calcining at 500 0 C in air for 30 h. A transmission electron microscopy was used to characterize the nanowire morphologies. Raman spectra were performed to study the CuO nanowire arrays. After measuring, we found that the current-voltage curve of the CuO nanowires is nonlinear.

Moessbauer study of Fe-Co nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2002-01-28

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

Dosimetric properties of MOS transistors

International Nuclear Information System (INIS)

Frank, H.; Petr, I.

1977-01-01

The structure of MOS transistors is described and their characteristics given. The experiments performed and data in the literature show the following dosimetric properties of MOS transistors: while for low gamma doses the transistor response to exposure is linear, it shows saturation for higher doses (exceeding 10 3 Gy in tissue). The response is independent of the energy of radiation and of the dose rate (within 10 -2 to 10 5 Gy/s). The spontaneous reduction with time of the spatial charge captured by the oxide layer (fading) is small and acceptable from the point of view of dosimetry. Curves are given of isochronous annealing of the transistors following irradiation with 137 Cs and 18 MeV electrons for different voltages during irradiation. The curves show that in MOS transistors irradiated with high-energy electrons the effect of annealing is less than in transistors irradiated with 137 Cs. In view of the requirement of using higher temperatures (approx. 400 degC) for the complete ''erasing'' of the captured charge, unsealed systems must be used for dosimetric purposes. The effect was also studied of neutron radiation, proton radiation and electron radiation on the MOS transistor structure. For MOS transistor irradiation with 14 MeV neutrons from a neutron generator the response was 4% of that for gamma radiation at the same dose equivalent. The effect of proton radiation was studied as related to the changes in MOS transistor structure during space flights. The response curve shapes are similar to those of gamma radiation curves. The effect of electron radiation on the MOS structure was studied by many authors. The experiments show that for each thickness of the SiO 2 layer an electron energy exists at which the size of the charge captured in SiO 2 is the greatest. All data show that MOS transistors are promising for radiation dosimetry. The main advantage of MOS transistors as gamma dosemeters is the ease and speed of evaluation, low sensitivity to neutron

Colour tuneable light-emitting transistor

Energy Technology Data Exchange (ETDEWEB)

Feldmeier, Eva J.; Melzer, Christian; Seggern, Heinz von [Electronic Materials Department, Institute of Materials Science, Technische Universitaet Darmstadt (Germany)

2010-07-01

In recent years the interest in ambipolar organic light-emitting field-effect transistors has increased steadily as the devices combine switching behaviour of transistors with light emission. Usually, small molecules and polymers with a band gap in the visible spectral range serve as semiconducting materials. Mandatory remain balanced injection and transport properties for both charge carrier types to provide full control of the spatial position of the recombination zone of electrons and holes in the transistor channel via the applied voltages. As will be presented here, the spatial control of the recombination zone opens new possibilities towards light-emitting devices with colour tuneable emission. In our contribution an organic light-emitting field-effect transistors is presented whose emission colour can be changed by the applied voltages. The organic top-contact field-effect transistor is based on a parallel layer stack of acenes serving as organic transport and emission layers. The transistor displays ambipolar characteristics with a narrow recombination zone within the transistor channel. During operation the recombination zone can be moved by a proper change in the drain and gate bias from one organic semiconductor layer to another one inducing a change in the emission colour. In the presented example the emission maxima can be switched from 530 nm to 580 nm.

Biofunctionalized Magnetic Nanowires

KAUST Repository

Kosel, Jurgen

2013-12-19

Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

Biofunctionalized Magnetic Nanowires

KAUST Repository

Kosel, Jü rgen; Ravasi, Timothy; Contreras Gerenas, Maria Fernanda

2013-01-01

Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

Magnetic drug delivery with FePd nanowires

Energy Technology Data Exchange (ETDEWEB)

Pondman, Kirsten M.; Bunt, Nathan D. [Neuro Imaging, MIRA Institute, University of Twente, Enschede (Netherlands); Maijenburg, A. Wouter [Inorganic Material Science, MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Wezel, Richard J.A. van [Biomedical Signals and Systems, MIRA, Twente University, Enschede (Netherlands); Kishore, Uday [Centre for Infection, Immunity and Disease Mechanisms, Biosciences, Brunel University, London (United Kingdom); Abelmann, Leon [Transducer Science and Technology group, MESA+ Institute for nanotechnology, University of Twente, Enschede (Netherlands); Elshof, Johan E. ten [Inorganic Material Science, MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Haken, Bennie ten, E-mail: b.tenhaken@utwente.nl [Neuro Imaging, MIRA Institute, University of Twente, Enschede (Netherlands)

2015-04-15

Magnetic drug delivery is a promising method to target a drug to a diseased area while reducing negative side effects caused by systemic administration of drugs. In magnetic drug delivery a therapeutic agent is coupled to a magnetic nanoparticle. The particles are injected and at the target location withdrawn from blood flow by a magnetic field. In this study a FePd nanowire is developed with optimised properties for magnetic targeting. The nanowires have a high magnetic moment to reduce the field gradient needed to capture them with a magnet. The dimensions and the materials of the nanowire and coating are such that they are dispersable in aqueous media, non-cytotoxic, easily phagocytosed and not complement activating. This is established in several in-vitro tests with macrophage and endothelial cell lines. Along with the nanowires a magnet is designed, optimised for capture of the nanowires from the blood flow in the hind leg of a rat. The system is used in a pilot scale in-vivo experiment. No negative side effects from injection of the nanowires were found within the limited time span of the experiment. In this first pilot experiment no nanowires were found to be targeted by the magnet, or in the liver, kidneys or spleen, most likely the particles were removed during the fixation procedure. - Highlights: • Description of the magnetic properties of nanowires. • Design and characterisation of a biocompatible FePd nanowire. • In-vitro cytotoxicity analysis and immune system responses. • In-vivo magnetic drug delivery using the developed nanowires.

Comparison of the top-down and bottom-up approach to fabricate nanowire-based Silicon/Germanium heterostructures

International Nuclear Information System (INIS)

Wolfsteller, A.; Geyer, N.; Nguyen-Duc, T.-K.; Das Kanungo, P.; Zakharov, N.D.; Reiche, M.; Erfurth, W.; Blumtritt, H.; Werner, P.; Goesele, U.

2010-01-01

Silicon nanowires (NWs) and vertical nanowire-based Si/Ge heterostructures are expected to be building blocks for future devices, e.g. field-effect transistors or thermoelectric elements. In principle two approaches can be applied to synthesise these NWs: the 'bottom-up' and the 'top-down' approach. The most common method for the former is the vapour-liquid-solid (VLS) mechanism which can also be applied to grow NWs by molecular beam epitaxy (MBE). Although MBE allows a precise growth control under highly reproducible conditions, the general nature of the growth process via a eutectic droplet prevents the synthesis of heterostructures with sharp interfaces and high Ge concentrations. We compare the VLS NW growth with two different top-down methods: The first is a combination of colloidal lithography and metal-assisted wet chemical etching, which is an inexpensive and fast method and results in large arrays of homogenous Si NWs with adjustable diameters down to 50 nm. The second top-down method combines the growth of Si/Ge superlattices by MBE with electron beam lithography and reactive ion etching. Again, large and homogeneous arrays of NWs were created, this time with a diameter of 40 nm and the Si/Ge superlattice inside.

Epitaxy of advanced nanowire quantum devices

Science.gov (United States)

Gazibegovic, Sasa; Car, Diana; Zhang, Hao; Balk, Stijn C.; Logan, John A.; de Moor, Michiel W. A.; Cassidy, Maja C.; Schmits, Rudi; Xu, Di; Wang, Guanzhong; Krogstrup, Peter; Op Het Veld, Roy L. M.; Zuo, Kun; Vos, Yoram; Shen, Jie; Bouman, Daniël; Shojaei, Borzoyeh; Pennachio, Daniel; Lee, Joon Sue; van Veldhoven, Petrus J.; Koelling, Sebastian; Verheijen, Marcel A.; Kouwenhoven, Leo P.; Palmstrøm, Chris J.; Bakkers, Erik P. A. M.

2017-08-01

Semiconductor nanowires are ideal for realizing various low-dimensional quantum devices. In particular, topological phases of matter hosting non-Abelian quasiparticles (such as anyons) can emerge when a semiconductor nanowire with strong spin-orbit coupling is brought into contact with a superconductor. To exploit the potential of non-Abelian anyons—which are key elements of topological quantum computing—fully, they need to be exchanged in a well-controlled braiding operation. Essential hardware for braiding is a network of crystalline nanowires coupled to superconducting islands. Here we demonstrate a technique for generic bottom-up synthesis of complex quantum devices with a special focus on nanowire networks with a predefined number of superconducting islands. Structural analysis confirms the high crystalline quality of the nanowire junctions, as well as an epitaxial superconductor-semiconductor interface. Quantum transport measurements of nanowire ‘hashtags’ reveal Aharonov-Bohm and weak-antilocalization effects, indicating a phase-coherent system with strong spin-orbit coupling. In addition, a proximity-induced hard superconducting gap (with vanishing sub-gap conductance) is demonstrated in these hybrid superconductor-semiconductor nanowires, highlighting the successful materials development necessary for a first braiding experiment. Our approach opens up new avenues for the realization of epitaxial three-dimensional quantum architectures which have the potential to become key components of various quantum devices.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Dosimetric properties of MOS transistors

International Nuclear Information System (INIS)

Peter, I.; Frank, G.

1977-01-01

The performance of MOS transistors as gamma detectors has been tested. The dosimeter sensitivity has proved to be independent on the doses ranging from 10 3 to 10 6 R, and gamma energy of 137 Cs, 60 Co - sources and 5 - 18 MeV electrons. Fading of the space charge trapped by the SiO 2 layer of the transistor has appeared to be neglegible at room temperature after 400 hrs. The isochronous annealing in the temperature range of 40-260 deg C had a more substantial effect on the space charge of the transistor irradiated with 18 MeV electrons than on the 137 Cs gamma-irradiated transistors. This proved a repeated use of γ-dosemeters. MOS transistors are concluded to be promising for gamma dosimetry [ru

Electrochemical synthesis of CORE-shell magnetic nanowires

KAUST Repository

Ovejero, Jesús G.

2015-04-16

(Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloys). Novel opportunities offered by such nanowires are discussed particularly the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare TM nanowires. These core-shell nanowires can be released from the template so, opening novel opportunities for biofunctionalization of individual nanowires.

Metal-dielectric-CNT nanowires for surface-enhanced Raman spectroscopy

Science.gov (United States)

Bond, Tiziana C.; Altun, Ali; Park, Hyung Gyu

2017-10-03

A sensor with a substrate includes nanowires extending vertically from the substrate, a hafnia coating on the nanowires that provides hafnia coated nanowires, and a noble metal coating on the hafnia coated nanowires. The top of the hafnia and noble metal coated nanowires bent onto one another to create a canopy forest structure. There are numerous randomly arranged holes that let through scattered light. The many points of contact, hot spots, amplify signals. The methods include the steps of providing a Raman spectroscopy substrate, introducing nano crystals to the Raman spectroscopy substrate, growing a forest of nanowires from the nano crystals on the Raman spectroscopy substrate, coating the nanowires with hafnia providing hafnia coated nanowires, and coating the hafnia coated nanowires with a noble metal or other metal.

Design and Characterisation of III-V Semiconductor Nanowire Lasers

Science.gov (United States)

Saxena, Dhruv

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

Transistor-based particle detection systems and methods

Science.gov (United States)

Jain, Ankit; Nair, Pradeep R.; Alam, Muhammad Ashraful

2015-06-09

Transistor-based particle detection systems and methods may be configured to detect charged and non-charged particles. Such systems may include a supporting structure contacting a gate of a transistor and separating the gate from a dielectric of the transistor, and the transistor may have a near pull-in bias and a sub-threshold region bias to facilitate particle detection. The transistor may be configured to change current flow through the transistor in response to a change in stiffness of the gate caused by securing of a particle to the gate, and the transistor-based particle detection system may configured to detect the non-charged particle at least from the change in current flow.

Reversal modes in asymmetric Ni nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2012-11-15

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

Electron irradiation of power transistors

International Nuclear Information System (INIS)

Hower, P.L.; Fiedor, R.J.

1982-01-01

A method for reducing storage time and gain parameters in a semiconductor transistor includes the step of subjecting the transistor to electron irradiation of a dosage determined from measurements of the parameters of a test batch of transistors. Reduction of carrier lifetime by proton bombardment and gold doping is mentioned as an alternative to electron irradiation. (author)

Thermal History Devices, Systems For Thermal History Detection, And Methods For Thermal History Detection

KAUST Repository

Caraveo Frescas, Jesus Alfonso; Alshareef, Husam N.

2015-01-01

Embodiments of the present disclosure include nanowire field-effect transistors, systems for temperature history detection, methods for thermal history detection, a matrix of field effect transistors, and the like.

Thermal History Devices, Systems For Thermal History Detection, And Methods For Thermal History Detection

KAUST Repository

Caraveo Frescas, Jesus Alfonso

2015-05-28

Embodiments of the present disclosure include nanowire field-effect transistors, systems for temperature history detection, methods for thermal history detection, a matrix of field effect transistors, and the like.

Stability of Organic Nanowires

DEFF Research Database (Denmark)

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

2011-01-01

The morphological stability of organic nanowires over time and under thermal load is of major importance for their use in any device. In this study the growth and stability of organic nanowires from a naphthyl end-capped thiophene grown by organic molecular beam deposition is investigated via ato...

Diluted magnetic semiconductor nanowires exhibiting magnetoresistance

Science.gov (United States)

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

2011-08-23

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

Au nanowire junction breakup through surface atom diffusion

Science.gov (United States)

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

2018-01-01

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

Core-shell magnetic nanowires fabrication and characterization

Energy Technology Data Exchange (ETDEWEB)

Kalska-Szostko, B., E-mail: kalska@uwb.edu.pl [Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok (Poland); Faculty of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Bialystok, Poland (Poland); Klekotka, U.; Satuła, D. [Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok (Poland); Faculty of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Bialystok, Poland (Poland)

2017-02-28

Highlights: • New approach for nanowires modification are presented. • Physical and chemical characterization of the nanowires are shown. • Properties modulations as an effect of the surface layer composition are discussed. - Abstract: In this paper, a new way of the preparation of core-shell magnetic nanowires has been proposed. For the modification Fe nanowires were prepared by electrodeposition in anodic aluminium oxide matrixes, in first step. In second, by wetting chemical deposition, shell layers of Ag, Au or Cu were obtained. Resultant core-shell nanowires structure was characterized by X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray. Whereas magnetic properties by Mössbauer spectroscopy.

Template-based fabrication of nanowire-nanotube hybrid arrays

International Nuclear Information System (INIS)

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

2008-01-01

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

Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

International Nuclear Information System (INIS)

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

2015-01-01

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

The point of practical use for the transistor circuit

International Nuclear Information System (INIS)

1996-01-01

This is comprised of eight chapters and goes as follows; what is transistor? the first step for use of transistor such as connection between power and signal source, static characteristic of transistor and equivalent circuit of transistor, design of easy small-signal amplifier circuit, design for amplification of electric power and countermeasure for prevention of trouble, transistor concerned interface, transistor circuit around micro computer, transistor in active use of FET and power circuit and transistor. It has an appendix on transistor and design of bias of FET circuits like small signal transistor circuit and FET circuit.

Silicon on insulator self-aligned transistors

Science.gov (United States)

McCarthy, Anthony M.

2003-11-18

A method for fabricating thin-film single-crystal silicon-on-insulator (SOI) self-aligned transistors. Standard processing of silicon substrates is used to fabricate the transistors. Physical spaces, between the source and gate, and the drain and gate, introduced by etching the polysilicon gate material, are used to provide connecting implants (bridges) which allow the transistor to perform normally. After completion of the silicon substrate processing, the silicon wafer is bonded to an insulator (glass) substrate, and the silicon substrate is removed leaving the transistors on the insulator (glass) substrate. Transistors fabricated by this method may be utilized, for example, in flat panel displays, etc.

Physical limits of silicon transistors and circuits

International Nuclear Information System (INIS)

Keyes, Robert W

2005-01-01

A discussion on transistors and electronic computing including some history introduces semiconductor devices and the motivation for miniaturization of transistors. The changing physics of field-effect transistors and ways to mitigate the deterioration in performance caused by the changes follows. The limits of transistors are tied to the requirements of the chips that carry them and the difficulties of fabricating very small structures. Some concluding remarks about transistors and limits are presented

Quantum transport in nanowire-based hybrid devices

Energy Technology Data Exchange (ETDEWEB)

Guenel, Haci Yusuf

2013-05-08

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

Electrochemical synthesis of highly crystalline copper nanowires

International Nuclear Information System (INIS)

Kaur, Amandeep; Gupta, Tanish; Kumar, Akshay; Kumar, Sanjeev; Singh, Karamjeet; Thakur, Anup

2015-01-01

Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

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)].

Bending and tensile deformation of metallic nanowires

International Nuclear Information System (INIS)

McDowell, Matthew T; Leach, Austin M; Gall, Ken

2008-01-01

Using molecular statics simulations and the embedded atom method, a technique for bending silver nanowires and calculating Young's modulus via continuum mechanics has been developed. The measured Young's modulus values extracted from bending simulations were compared with modulus values calculated from uniaxial tension simulations for a range of nanowire sizes, orientations and geometries. Depending on axial orientation, the nanowires exhibit stiffening or softening under tension and bending as size decreases. Bending simulations typically result in a greater variation of Young's modulus values with nanowire size compared with tensile deformation, which indicates a loading-method-dependent size effect on elastic properties at sub-5 nm wire diameters. Since the axial stress is maximized at the lateral surfaces in bending, the loading-method-dependent size effect is postulated to be primarily a result of differences in nanowire surface and core elastic modulus. The divergence of Young's modulus from the bulk modulus in these simulations occurs at sizes below the range in which experiments have demonstrated a size scale effect on elastic properties of metallic nanowires. This difference indicates that other factors beyond native metallic surface properties play a role in experimentally observed nanowire elastic modulus size effects

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

Science.gov (United States)

Dubrovskii, V. G.

2017-11-01

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

Solution-processed copper-nickel nanowire anodes for organic solar cells

Science.gov (United States)

Stewart, Ian E.; Rathmell, Aaron R.; Yan, Liang; Ye, Shengrong; Flowers, Patrick F.; You, Wei; Wiley, Benjamin J.

2014-05-01

This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%.This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01024h

Nanowire sensor, sensor array, and method for making the same

Science.gov (United States)

Yun, Minhee (Inventor); Myung, Nosang (Inventor); Vasquez, Richard (Inventor); Homer, Margie (Inventor); Ryan, Margaret (Inventor); Yen, Shiao-Pin (Inventor); Fleurial, Jean-Pierre (Inventor); Bugga, Ratnakumar (Inventor); Choi, Daniel (Inventor); Goddard, William (Inventor)

2012-01-01

The present invention relates to a nanowire sensor and method for forming the same. More specifically, the nanowire sensor comprises at least one nanowire formed on a substrate, with a sensor receptor disposed on a surface of the nanowire, thereby forming a receptor-coated nanowire. The nanowire sensor can be arranged as a sensor sub-unit comprising a plurality of homogeneously receptor-coated nanowires. A plurality of sensor subunits can be formed to collectively comprise a nanowire sensor array. Each sensor subunit in the nanowire sensor array can be formed to sense a different stimulus, allowing a user to sense a plurality of stimuli. Additionally, each sensor subunit can be formed to sense the same stimuli through different aspects of the stimulus. The sensor array is fabricated through a variety of techniques, such as by creating nanopores on a substrate and electrodepositing nanowires within the nanopores.

Diamond nanowires: fabrication, structure, properties, and applications.

Science.gov (United States)

Yu, Yuan; Wu, Liangzhuan; Zhi, Jinfang

2014-12-22

C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Young's modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pattern analysis of aligned nanowires in a microchannel

International Nuclear Information System (INIS)

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

2013-01-01

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

Charging effects and surface potential variations of Cu-based nanowires

Energy Technology Data Exchange (ETDEWEB)

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

2016-02-29

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

Selective growth of gallium nitride nanowires by femtosecond laser patterning

International Nuclear Information System (INIS)

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

2008-01-01

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

Selective growth of gallium nitride nanowires by femtosecond laser patterning

Energy Technology Data Exchange (ETDEWEB)

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

2008-01-31

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

Quantum transport in semiconductor nanowires

NARCIS (Netherlands)

Van Dam, J.

2006-01-01

This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS)

Angular Magnetoresistance of Nanowires with Alternating Cobalt and Nickel Segments

KAUST Repository

Mohammed, Hanan

2017-06-22

Magnetization reversal in segmented Co/Ni nanowires with varying number of segments was studied using angular Magnetoresistance (MR) measurements on isolated nanowires. The MR measurements offer an insight into the pinning of domain walls within the nanowires. Angular MR measurements were performed on nanowires with two and multiple segments by varying the angle between the applied magnetic field and nanowire (−90° ≤θ≤90°). The angular MR measurements reveal that at lower values of θ the switching fields are nearly identical for the multisegmented and two-segmented nanowires, whereas at higher values of θ, a decrease in the switching field is observed in the case of two segmented nanowires. The two segmented nanowires generally exhibit a single domain wall pinning event, whereas an increased number of pinning events are characteristic of the multisegmented nanowires at higher values of θ. In-situ magnetic force microscopy substantiates reversal by domain wall nucleation and propagation in multisegmented nanowires.

Angular Magnetoresistance of Nanowires with Alternating Cobalt and Nickel Segments

KAUST Repository

Mohammed, Hanan; Corte-Leon, H.; Ivanov, Yurii P.; Moreno, J. A.; Kazakova, O.; Kosel, Jü rgen

2017-01-01

Magnetization reversal in segmented Co/Ni nanowires with varying number of segments was studied using angular Magnetoresistance (MR) measurements on isolated nanowires. The MR measurements offer an insight into the pinning of domain walls within the nanowires. Angular MR measurements were performed on nanowires with two and multiple segments by varying the angle between the applied magnetic field and nanowire (−90° ≤θ≤90°). The angular MR measurements reveal that at lower values of θ the switching fields are nearly identical for the multisegmented and two-segmented nanowires, whereas at higher values of θ, a decrease in the switching field is observed in the case of two segmented nanowires. The two segmented nanowires generally exhibit a single domain wall pinning event, whereas an increased number of pinning events are characteristic of the multisegmented nanowires at higher values of θ. In-situ magnetic force microscopy substantiates reversal by domain wall nucleation and propagation in multisegmented nanowires.

Wireless thin film transistor based on micro magnetic induction coupling antenna.

Science.gov (United States)

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-12-22

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the 'internet of things' (IoT).

Wireless thin film transistor based on micro magnetic induction coupling antenna

Science.gov (United States)

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-12-01

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

Ultraviolet photodetectors made from SnO2 nanowires

International Nuclear Information System (INIS)

Wu, Jyh-Ming; Kuo, Cheng-Hsiang

2009-01-01

SnO 2 nanowires can be synthesized on alumina substrates and formed into an ultraviolet (UV) photodetector. The photoelectric current of the SnO 2 nanowires exhibited a rapid photo-response as a UV lamp was switched on and off. The ratio of UV-exposed current to dark current has been investigated. The SnO 2 nanowires were synthesized by a vapor-liquid-solid process at a temperature of 900 o C. It was found that the nanowires were around 70-100 nm in diameter and several hundred microns in length. High-resolution transmission electron microscopy (HRTEM) image indicated that the nanowires grew along the [200] axis as a single crystallinity. Cathodoluminescence (CL), thin-film X-ray diffractometry, and X-ray photoelectron spectroscopy (XPS) were used to characterize the as-synthesized nanowires.

Pd nanowire arrays as electrocatalysts for ethanol electrooxidation

Energy Technology Data Exchange (ETDEWEB)

Wang, Hong; Cheng, Faliang [Dongguan University of Technology, Dongguan 523106 (China); Xu, Changwei; Jiang, Sanping [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

2007-05-15

Highly ordered Pd nanowire arrays were prepared by template-electrodeposition method using anodic aluminum oxide template. The Pd nanowire arrays, in this paper, have high electrochemical active surface and show excellent catalytic properties for ethanol electrooxidation in alkaline media. The activity of Pd nanowire arrays for ethanol oxidation is not only higher that of Pd film, but also higher than that of commercial E-TEK PtRu(2:1 by weight)/C. The micrometer sized pores and channels in nanowire arrays act as structure units. They make liquid fuel diffuse into and products diffuse out of the catalysts layer much easier, therefore, the utilization efficiency of catalysts gets higher. Pd nanowire arrays are stable catalysts for ethanol oxidation. The nanowire arrays may be a great potential in direct ethanol fuel cells and ethanol sensors. (author)

Synthetic Strategies and Applications of GaN Nanowires

Directory of Open Access Journals (Sweden)

Guoquan Suo

2014-01-01

Full Text Available GaN is an important III-V semiconductor material with a direct band gap of 3.4 eV at 300 K. The wide direct band gap makes GaN an attractive material for various applications. GaN nanowires have demonstrated significant potential as fundamental building blocks for nanoelectronic and nanophotonic devices and also offer substantial promise for integrated nanosystems. In this paper, we provide a comprehensive review on the general synthetic strategies, characterizations, and applications of GaN nanowires. We first summarize several growth techniques of GaN nanowires. Subsequently, we discuss mechanisms involved to generate GaN nanowires from different synthetic schemes and conditions. Then we review some characterization methods of GaN nanowires. Finally, several kinds of main applications of GaN nanowires are discussed.

Power transistor module for high current applications

International Nuclear Information System (INIS)

Cilyo, F.F.

1975-01-01

One of the parts needed for the control system of the 400-GeV accelerator at Fermilab was a power transistor with a safe operating area of 1800A at 50V, dc current gain of 100,000 and 20 kHz bandwidth. Since the commercially available discrete devices and power hybrid packages did not meet these requirements, a power transistor module was developed which performed satisfactorily. By connecting 13 power transistors in parallel, with due consideration for network and heat dissipation problems, and by driving these 13 with another power transistor, a super power transistor is made, having an equivalent current, power, and safe operating area capability of 13 transistors. For higher capabilities, additional modules can be conveniently added. (auth)

Analysing organic transistors based on interface approximation

International Nuclear Information System (INIS)

Akiyama, Yuto; Mori, Takehiko

2014-01-01

Temperature-dependent characteristics of organic transistors are analysed thoroughly using interface approximation. In contrast to amorphous silicon transistors, it is characteristic of organic transistors that the accumulation layer is concentrated on the first monolayer, and it is appropriate to consider interface charge rather than band bending. On the basis of this model, observed characteristics of hexamethylenetetrathiafulvalene (HMTTF) and dibenzotetrathiafulvalene (DBTTF) transistors with various surface treatments are analysed, and the trap distribution is extracted. In turn, starting from a simple exponential distribution, we can reproduce the temperature-dependent transistor characteristics as well as the gate voltage dependence of the activation energy, so we can investigate various aspects of organic transistors self-consistently under the interface approximation. Small deviation from such an ideal transistor operation is discussed assuming the presence of an energetically discrete trap level, which leads to a hump in the transfer characteristics. The contact resistance is estimated by measuring the transfer characteristics up to the linear region

Transformation of bulk alloys to oxide nanowires

Science.gov (United States)

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

2017-01-01

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

Superconductive silicon nanowires using gallium beam lithography.

Energy Technology Data Exchange (ETDEWEB)

Henry, Michael David; Jarecki, Robert Leo,

2014-01-01

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

Silicon nanowire-based solar cells

Energy Technology Data Exchange (ETDEWEB)

Stelzner, Th; Pietsch, M; Andrae, G; Falk, F; Ose, E; Christiansen, S [Institute of Photonic Technology, Albert-Einstein-Strasse 9, D-07745 Jena (Germany)], E-mail: thomas.stelzner@ipht-jena.de

2008-07-23

The fabrication of silicon nanowire-based solar cells on silicon wafers and on multicrystalline silicon thin films on glass is described. The nanowires show a strong broadband optical absorption, which makes them an interesting candidate to serve as an absorber in solar cells. The operation of a solar cell is demonstrated with n-doped nanowires grown on a p-doped silicon wafer. From a partially illuminated area of 0.6 cm{sup 2} open-circuit voltages in the range of 230-280 mV and a short-circuit current density of 2 mA cm{sup -2} were obtained.

Silicon nanowire-based solar cells

International Nuclear Information System (INIS)

Stelzner, Th; Pietsch, M; Andrae, G; Falk, F; Ose, E; Christiansen, S

2008-01-01

The fabrication of silicon nanowire-based solar cells on silicon wafers and on multicrystalline silicon thin films on glass is described. The nanowires show a strong broadband optical absorption, which makes them an interesting candidate to serve as an absorber in solar cells. The operation of a solar cell is demonstrated with n-doped nanowires grown on a p-doped silicon wafer. From a partially illuminated area of 0.6 cm 2 open-circuit voltages in the range of 230-280 mV and a short-circuit current density of 2 mA cm -2 were obtained

Long-range magnetostatic interactions in arrays of nanowires

CERN Document Server

Raposo, V; González, J M; Vázquez, M

2000-01-01

Experimental measurements and micromagnetic simulations of the hysteresis loops of arrays of cobalt nanowires are compared here. Arrays of cobalt nanowires (200 nm in diameter) were electrodeposited into the pores of alumina membranes (thickness 60 mu m). Their hysteresis loops along the axial direction of nanowires were measured using vibrating sample magnetometry. Micromagnetic simulations were performed considering dipolar interaction between nanowires leading to similar hysteresis loops as those obtained experimentally.

Impact of Process Technologies on ELDRS of Bipolar Transistors

International Nuclear Information System (INIS)

Lu Wu; Ren Diyuan; Guo Qi; Yu Xuefeng; Zheng Yuzhan

2010-01-01

Radiation effects under different dose rates and annealing behaviors of domestic bipolar transistors, with same manufacture technology, were investigated.These transistors include NPN transistors of various emitter area, and LPNP transistors with different doping concentrations in emitter. It is shown that different types of transistors have different radiation responses. The results of NPN transistors show that more degradation occurs at less emitter area. Yet, the results of LPNP transistors demonstrate that transistors with lightly doped emitter are more sensitive to radiation, compared with heavily doped emitter. Finally,the mechanisms of the difference between various radiation responses were analyzed. (authors)

Enhanced photovoltaic performance of an inclined nanowire array solar cell.

Science.gov (United States)

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

2015-11-30

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

Constricted nanowire with stabilized magnetic domain wall

International Nuclear Information System (INIS)

Sbiaa, R.; Al Bahri, M.

2016-01-01

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

Distributed amplifier using Josephson vortex flow transistors

International Nuclear Information System (INIS)

McGinnis, D.P.; Beyer, J.B.; Nordman, J.E.

1986-01-01

A wide-band traveling wave amplifier using vortex flow transistors is proposed. A vortex flow transistor is a long Josephson junction used as a current controlled voltage source. The dual nature of this device to the field effect transistor is exploited. A circuit model of this device is proposed and a distributed amplifier utilizing 50 vortex flow transistors is predicted to have useful gain to 100 GHz

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

Science.gov (United States)

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

2018-06-01

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

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)

Photosensitive graphene transistors.

Science.gov (United States)

Li, Jinhua; Niu, Liyong; Zheng, Zijian; Yan, Feng

2014-08-20

High performance photodetectors play important roles in the development of innovative technologies in many fields, including medicine, display and imaging, military, optical communication, environment monitoring, security check, scientific research and industrial processing control. Graphene, the most fascinating two-dimensional material, has demonstrated promising applications in various types of photodetectors from terahertz to ultraviolet, due to its ultrahigh carrier mobility and light absorption in broad wavelength range. Graphene field effect transistors are recognized as a type of excellent transducers for photodetection thanks to the inherent amplification function of the transistors, the feasibility of miniaturization and the unique properties of graphene. In this review, we will introduce the applications of graphene transistors as photodetectors in different wavelength ranges including terahertz, infrared, visible, and ultraviolet, focusing on the device design, physics and photosensitive performance. Since the device properties are closely related to the quality of graphene, the devices based on graphene prepared with different methods will be addressed separately with a view to demonstrating more clearly their advantages and shortcomings in practical applications. It is expected that highly sensitive photodetectors based on graphene transistors will find important applications in many emerging areas especially flexible, wearable, printable or transparent electronics and high frequency communications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodeposited highly-ordered manganese oxide nanowire arrays for supercapacitors

Science.gov (United States)

Liu, Haifeng; Lu, Bingqiang; Wei, Shuiqiang; Bao, Mi; Wen, Yanxuan; Wang, Fan

2012-07-01

Large arrays of well-aligned Mn oxide nanowires were prepared by electrodeposition using anodic aluminum oxide templates. The sizes of nanowires were tuned by varying the electrotype solution involved and the MnO2 nanowires with 10 μm in length were obtained in a neutral KMnO4 bath for 1 h. MnO2 nanowire arrays grown on conductor substance save the tedious electrode-making process, and electrochemical characterization demonstrates that the MnO2 nanowire arrays electrode has good capacitive behavior. Due to the limited mass transportation in narrow spacing, the spacing effects between the neighbor nanowires have show great influence to the electrochemical performance.

Biofunctionalization of zinc oxide nanowires for DNA sensory applications

Directory of Open Access Journals (Sweden)

Rudolph Bettina

2011-01-01

Full Text Available Abstract We report on the biofunctionalization of zinc oxide nanowires for the attachment of DNA target molecules on the nanowire surface. With the organosilane glycidyloxypropyltrimethoxysilane acting as a bifunctional linker, amino-modified capture molecule oligonucleotides have been immobilized on the nanowire surface. The dye-marked DNA molecules were detected via fluorescence microscopy, and our results reveal a successful attachment of DNA capture molecules onto the nanowire surface. The electrical field effect induced by the negatively charged attached DNA molecules should be able to control the electrical properties of the nanowires and gives way to a ZnO nanowire-based biosensing device.

Morphology Controlled Fabrication of InN Nanowires on Brass Substrates

Directory of Open Access Journals (Sweden)

Huijie Li

2016-10-01

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

Surface enhanced infrared spectroscopy using interacting gold nanowires

Energy Technology Data Exchange (ETDEWEB)

Neubrech, Frank; Weber, Daniel; Pucci, Annemarie [Kirchhoff-Institut fuer Physik, Heidelberg (Germany); Shen, Hong [Universite Troyes, Troyes (France); Lamy de la Chapelle, Marc [Universite Paris 13, Bobigny (France)

2009-07-01

We performed surface enhanced infrared spectroscopy (SEIRS) of molecules adsorbed on gold nanowires using synchrotron light of the ANKA IR-beamline at the Forschungszentrum Karlsruhe (Germany). Arrays of gold nanowires with interparticle spacings down to 30nm were prepared by electron beam lithography. The interparticle distance was reduced further by wet-chemically increasing the size of the gold nanowires. The growth of the wires was proofed using IR spectroscopy as well as scanning electron microscopy. After this preparation step, appropriate arrays of nanowires with an interparticle distance down to a few nanometers were selected to demonstrate the surface enhanced infrared spectroscopy of one monolayer octadecanthiol (ODT). As know from SEIRS studies using single gold nanowires, the spectral position of the antenna-like resonance in relation to the absorption bands of ODT (2850cm-1 and 2919cm-1) is crucial for both, the lineshape of the molecular vibration and the signal enhancement. In contrast to single nanowires studies, a further increase of the enhanced signals is expected due to the interaction of the electromagnetic fields of the close-by nanowires.

Synthesis and electrical characterization of tungsten oxide nanowires

Institute of Scientific and Technical Information of China (English)

Huang Rui; Zhu Jing; Yu Rong

2009-01-01

Tungsten oxide nanowires of diameters ranging from 7 to 200 nm are prepared on a tungsten rod substrate by using the chemical vapour deposition (CVD) method with vapour-solid (VS) mechanism. Tin powders are used to control oxygen concentration in the furnace, thereby assisting the growth of the tungsten oxide nanowires. The grown tungsten oxide nanowires are determined to be of crystalline W18O49. Ⅰ-Ⅴ curves are measured by an in situ transmission electron microscope (TEM) to investigate the electrical properties of the nanowires. All of the Ⅰ-Ⅴ curves observed are symmetric, which reveals that the tungsten oxide nanowires are semiconducting. Quantitative analyses of the experimental I V curves by using a metal-semiconductor-metal (MSM) model give some intrinsic parameters of the tungsten oxide nanowires, such as the carrier concentration, the carrier mobility and the conductivity.

Semiconductor Nanowires and Nanotubes for Energy Conversion

Science.gov (United States)

Fardy, Melissa Anne

In recent years semiconductor nanowires and nanotubes have garnered increased attention for their unique properties. With their nanoscale dimensions comes high surface area and quantum confinement, promising enhancements in a wide range of applications. 1-dimensional nanostructures are especially attractive for energy conversion applications where photons, phonons, and electrons come into play. Since the bohr exciton radius and phonon and electron mean free paths are on the same length scales as nanowire diameters, optical, thermal, and electrical properties can be tuned by simple nanowire size adjustments. In addition, the high surface area inherent to nanowires and nanotubes lends them towards efficient charge separation and superior catalytic performance. In thermoelectric power generation, the nanoscale wire diameter can effectively scatter phonons, promoting reductions in thermal conductivity and enhancements in the thermoelectric figure of merit. To that end, single-crystalline arrays of PbS, PbSe, and PbTe nanowires have been synthesized by a chemical vapor transport approach. The electrical and thermal transport properties of the nanowires were characterized to investigate their potential as thermoelectric materials. Compared to bulk, the lead chalcogenide nanowires exhibit reduced thermal conductivity below 100 K by up to 3 orders of magnitude, suggesting that they may be promising thermoelectric materials. Smaller diameters and increased surface roughness are expected to give additional enhancements. The solution-phase synthesis of PbSe nanowires via oriented attachment of nanoparticles enables facile surface engineering and diameter control. Branched PbSe nanowires synthesized by this approach showed near degenerately doped charge carrier concentrations. Compared to the bulk, the PbSe nanowires exhibited a similar Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K. Thermal annealing of the Pb

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

As-Grown Gallium Nitride Nanowire Electromechanical Resonators

Science.gov (United States)

Montague, Joshua R.

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

Self-Assembled PbSe Nanowire:Perovskite Hybrids

KAUST Repository

Yang, Zhenyu

2015-12-02

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

Self-Assembled PbSe Nanowire:Perovskite Hybrids

KAUST Repository

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

2015-01-01

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

Gold nanoparticle-pentacene memory-transistors

OpenAIRE

Novembre , Christophe; Guerin , David; Lmimouni , Kamal; Gamrat , Christian; Vuillaume , Dominique

2008-01-01

We demonstrate an organic memory-transistor device based on a pentacene-gold nanoparticles active layer. Gold (Au) nanoparticles are immobilized on the gate dielectric (silicon dioxide) of a pentacene transistor by an amino-terminated self-assembled monolayer. Under the application of writing and erasing pulses on the gate, large threshold voltage shift (22 V) and on/off drain current ratio of ~3E4 are obtained. The hole field-effect mobility of the transistor is similar in the on and off sta...

Guiding modes of semi-infinite nanowire and their dispersion character

International Nuclear Information System (INIS)

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

2014-01-01

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

The Complete Semiconductor Transistor and Its Incomplete Forms

International Nuclear Information System (INIS)

Jie Binbin; Sah, C.-T.

2009-01-01

This paper describes the definition of the complete transistor. For semiconductor devices, the complete transistor is always bipolar, namely, its electrical characteristics contain both electron and hole currents controlled by their spatial charge distributions. Partially complete or incomplete transistors, via coined names or/and designed physical geometries, included the 1949 Shockley p/n junction transistor (later called Bipolar Junction Transistor, BJT), the 1952 Shockley unipolar 'field-effect' transistor (FET, later called the p/n Junction Gate FET or JGFET), as well as the field-effect transistors introduced by later investigators. Similarities between the surface-channel MOS-gate FET (MOSFET) and the volume-channel BJT are illustrated. The bipolar currents, identified by us in a recent nanometer FET with 2-MOS-gates on thin and nearly pure silicon base, led us to the recognition of the physical makeup and electrical current and charge compositions of a complete transistor and its extension to other three or more terminal signal processing devices, and also the importance of the terminal contacts.

Catalyst-free, III-V nanowire photovoltaics

Science.gov (United States)

Davies, D. G.; Lambert, N.; Fry, P. W.; Foster, A.; Krysa, A. B.; Wilson, L. R.

2014-05-01

We report on room temperature, photovoltaic operation of catalyst-free GaAs p-i-n junction nanowire arrays. Growth studies were first performed to determine the optimum conditions for controlling the vertical and lateral growth of the nanowires. Following this, devices consisting of axial p-i-n junctions were fabricated by planarising the nanowire arrays with a hard baked polymer. We discuss the photovoltaic properties of this proof-of-concept device, and significant improvements to be made during the growth.

On the thermomechanical deformation of silver shape memory nanowires

International Nuclear Information System (INIS)

Park, Harold S.; Ji, Changjiang

2006-01-01

We present an analysis of the uniaxial thermomechanical deformation of single-crystal silver shape memory nanowires using atomistic simulations. We first demonstrate that silver nanowires can show both shape memory and pseudoelastic behavior, then perform uniaxial tensile loading of the shape memory nanowires at various deformation temperatures, strain rates and heat transfer conditions. The simulations show that the resulting mechanical response of the shape memory nanowires depends strongly upon the temperature during deformation, and can be fundamentally different from that observed in bulk polycrystalline shape memory alloys. The energy and temperature signatures of uniaxially loaded silver shape memory nanowires are correlated to the observed nanowire deformation, and are further discussed in comparison to bulk polycrystalline shape memory alloy behavior

Large-area perovskite nanowire arrays fabricated by large-scale roll-to-roll micro-gravure printing and doctor blading

Science.gov (United States)

Hu, Qiao; Wu, Han; Sun, Jia; Yan, Donghang; Gao, Yongli; Yang, Junliang

2016-02-01

Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ~45%, temperature ~28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays with great potential applications in flexible electronic and optoelectronic devices.Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ~45%, temperature ~28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-12-15

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

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.

Tunable magnetic nanowires for biomedical and harsh environment applications

KAUST Repository

Ivanov, Yurii P.; Alfadhel, Ahmed; Al-Nassar, Mohammed Y.; Perez, Jose E.; Vazquez, Manuel; Chuvilin, Andrey; Kosel, Jü rgen

2016-01-01

We have synthesized nanowires with an iron core and an iron oxide (magnetite) shell by a facile low-cost fabrication process. The magnetic properties of the nanowires can be tuned by changing shell thicknesses to yield remarkable new properties and multi-functionality. A multi-domain state at remanence can be obtained, which is an attractive feature for biomedical applications, where a low remanence is desirable. The nanowires can also be encoded with different remanence values. Notably, the oxidation process of single-crystal iron nanowires halts at a shell thickness of 10 nm. The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations. This property renders these core-shell nanowires attractive materials for application to harsh environments. A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

Multi-spectral optical absorption in substrate-free nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

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

2014-09-22

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

Tunable magnetic nanowires for biomedical and harsh environment applications

KAUST Repository

Ivanov, Yurii P.

2016-04-13

We have synthesized nanowires with an iron core and an iron oxide (magnetite) shell by a facile low-cost fabrication process. The magnetic properties of the nanowires can be tuned by changing shell thicknesses to yield remarkable new properties and multi-functionality. A multi-domain state at remanence can be obtained, which is an attractive feature for biomedical applications, where a low remanence is desirable. The nanowires can also be encoded with different remanence values. Notably, the oxidation process of single-crystal iron nanowires halts at a shell thickness of 10 nm. The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations. This property renders these core-shell nanowires attractive materials for application to harsh environments. A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

Orientation-controlled synthesis and magnetism of single crystalline Co nanowires

International Nuclear Information System (INIS)

Huang, Gui-Fang; Huang, Wei-Qing; Wang, Ling-Ling; Zou, B.S.; Pan, Anlian

2012-01-01

Orientation control and the magnetic properties of single crystalline Co nanowires fabricated by electrodeposition have been systematically investigated. It is found that the orientation of Co nanowires can be effectively controlled by varying either the current density or the pore diameter of AAO templates. Lower current density or small diameter is favorable for forming the (1 0 0) texture, while higher current values or larger diameter leads to the emergence and enhancement of (1 1 0) texture of Co nanowires. The mechanism for the manipulated growth characterization is discussed in detail. The orientation of Co nanowires has a significant influence on the magnetic properties, resulting from the competition between the magneto-crystalline and shape anisotropy of Co nanowires. This work offers a simple method to manipulate the orientation and magnetic properties of nanowires for future applications. - Highlights: ► Single crystalline Co nanowires have successfully been grown by DC electrodeposition. ► Orientation controlling and its effect on magnetism of Co nanowires were investigated. ► The orientation of Co nanowires can be effectively controlled by varying current density. ► The crystalline orientation of Co nanowires has significant influence on the magnetic properties.

Piezoresistance of top-down suspended Si nanowires

International Nuclear Information System (INIS)

Koumela, A; Mercier, D; Dupre, C; Jourdan, G; Marcoux, C; Ollier, E; Duraffourg, L; Purcell, S T

2011-01-01

Measurements of the gauge factor of suspended, top-down silicon nanowires are presented. The nanowires are fabricated with a CMOS compatible process and with doping concentrations ranging from 2 x 10 20 down to 5 x 10 17 cm -3 . The extracted gauge factors are compared with results on identical non-suspended nanowires and with state-of-the-art results. An increase of the gauge factor after suspension is demonstrated. For the low doped nanowires a value of 235 is measured. Particular attention was paid throughout the experiments to distinguishing real resistance change due to strain modulation from resistance fluctuations due to charge trapping. Furthermore, a numerical model correlating surface charge density with the gauge factor is presented. Comparison of the simulations with experimental measurements shows the validity of this approach. These results contribute to a deeper understanding of the piezoresistive effect in Si nanowires.

Preparation and Characterization of Tin Oxide Nanowires

Directory of Open Access Journals (Sweden)

A. Kabiri

2013-12-01

Full Text Available The aim of this research is preparation of SnO2 nanowires by means of Thermal chemical reaction vapor transport deposition (TCRVTD method from SnO powders. The morphology, chemical composition and microstructure properties of the nanowires are characterized using field emission scanning electron microscope (FE-SEM, EDS, and XRD. The XRD diffraction patterns reveal that the SnO2 nanowires have been grown in the form of tetragonal crystal structures with the lattice parameter of a=b=0.440 nm, and c=0.370 nm. The SEM images reveal that SnO2 nanowires have successfully been grown on the Si substrate. The EDS patterns show that only elements of Sn, O and Au are detected. Prior to the VLS process the substrate is coated by a thin layer of Au. The diameter of nanowires is measured to be something between 20-100 nm.

Nanowire FET Based Neural Element for Robotic Tactile Sensing Skin

Directory of Open Access Journals (Sweden)

William Taube Navaraj

2017-09-01

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

Nanowires: properties, applications and synthesis via porous anodic ...

Indian Academy of Sciences (India)

Moreover, periodic arrays of magnetic nanowires hold high potential for recording media application. Nanowires are also potential candidates for sensor and bio-medical applications. In the present article, the physical and chemical properties of nanowires along with their probable applications in different fields have been ...

Corrosion detection of nanowires by magnetic sensors

KAUST Repository

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

2017-01-01

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

Corrosion detection of nanowires by magnetic sensors

KAUST Repository

Kosel, Jürgen

2017-10-05

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

A superconducting nanowire can be modeled by using SPICE

Science.gov (United States)

Berggren, Karl K.; Zhao, Qing-Yuan; Abebe, Nathnael; Chen, Minjie; Ravindran, Prasana; McCaughan, Adam; Bardin, Joseph C.

2018-05-01

Modeling of superconducting nanowire single-photon detectors typically requires custom simulations or finite-element analysis in one or two dimensions. Here, we demonstrate two simplified one-dimensional SPICE models of a superconducting nanowire that can quickly and efficiently describe the electrical characteristics of a superconducting nanowire. These models may be of particular use in understanding alternative architectures for nanowire detectors and readouts.

Magnetic phase shift reconstruction for uniformly magnetized nanowires

Energy Technology Data Exchange (ETDEWEB)

Akhtari-Zavareh, Azadeh [Department of Physics, Simon Fraser University, Burnaby, British Columbia (Canada); De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA (United States); Kavanagh, Karen L. [Department of Physics, Simon Fraser University, Burnaby, British Columbia (Canada)

2017-01-15

A new analytical model is developed for the magnetic phase shift of uniformly magnetized nanowires with ideal cylindrical geometry. The model is applied to experimental data from off-axis electron holography measurements of the phase shift of CoFeB nanowires, and the saturation induction of a selected wire, as well as its radius, aspect ratio, position and orientation, is determined by fitting the model parameters. The saturation induction value of 1.7 T of the CoFeB nanowire is found to be similar, to be within the measurement error, to values reported in the literature. - Highlights: • We describe a mathematical model for the magnetic phase shift of a cylindrical nanowire. • We discuss electron holography experiments on magnetic nanowires. • We obtain an accurate fit of the measured magnetic phase shift profile. • We extract the magnetic induction of the nanowire from the phase shift model. • The magnetic induction of 1.7 T agrees well with literature results.

A shortcut hydrothermal strategy for the synthesis of zinc nanowires

International Nuclear Information System (INIS)

Hu Jianqiang; Chen Zhiwu; Xie Jingsi; Yu Ying

2008-01-01

Synthesis of metal nanowires has opened many new possibilities for designing ideal building blocks for future nanodevices. In this work, zinc nanowires with lengths of micrometre magnitude were synthesized in high yield by a shortcut hydrothermal strategy. The synthesis involves a template-free, non-seed and catalyst-free solution-phase process to high-quality zinc nanowires, which is low-cost and proceeds at relatively short time. In this process, zinc nanowires were prepared through the reduction of zinc acetate with absolute ethanol in the presence of silver nitrate under hydrothermal atmosphere. The strategy suggests that silver ion plays a vital role in the synthesis of zinc nanowires, without which the substituted product is zinc oxide nanowires. X-ray diffraction and energy-dispersive x-ray spectroscopy measurements confirm the final formation of zinc nanowires and component transformation from zinc oxide nanowires in the introduction of silver ion. We believe that with the efficient synthesis, longer zinc nanowires can be fabricated and may find potential applications for superconductors and nanodevices. (fast track communication)

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

Additional compound semiconductor nanowires for photonics

Science.gov (United States)

Ishikawa, F.

2016-02-01

GaAs related compound semiconductor heterostructures are one of the most developed materials for photonics. Those have realized various photonic devices with high efficiency, e. g., lasers, electro-optical modulators, and solar cells. To extend the functions of the materials system, diluted nitride and bismide has been paid attention over the past decade. They can largely decrease the band gap of the alloys, providing the greater tunability of band gap and strain status, eventually suppressing the non-radiative Auger recombinations. On the other hand, selective oxidation for AlGaAs is a vital technique for vertical surface emitting lasers. That enables precisely controlled oxides in the system, enabling the optical and electrical confinement, heat transfer, and mechanical robustness. We introduce the above functions into GaAs nanowires. GaAs/GaAsN core-shell nanowires showed clear redshift of the emitting wavelength toward infrared regime. Further, the introduction of N elongated the carrier lifetime at room temperature indicating the passivation of non-radiative surface recombinations. GaAs/GaAsBi nanowire shows the redshift with metamorphic surface morphology. Selective and whole oxidations of GaAs/AlGaAs core-shell nanowires produce semiconductor/oxide composite GaAs/AlGaOx and oxide GaOx/AlGaOx core-shell nanowires, respectively. Possibly sourced from nano-particle species, the oxide shell shows white luminescence. Those property should extend the functions of the nanowires for their application to photonics.

Nano-soldering of magnetically aligned three-dimensional nanowire networks

International Nuclear Information System (INIS)

Gao Fan; Gu Zhiyong

2010-01-01

It is extremely challenging to fabricate 3D integrated nanostructures and hybrid nanoelectronic devices. In this paper, we report a simple and efficient method to simultaneously assemble and solder nanowires into ordered 3D and electrically conductive nanowire networks. Nano-solders such as tin were fabricated onto both ends of multi-segmented nanowires by a template-assisted electrodeposition method. These nanowires were then self-assembled and soldered into large-scale 3D network structures by magnetic field assisted assembly in a liquid medium with a high boiling point. The formation of junctions/interconnects between the nanowires and the scale of the assembly were dependent on the solder reflow temperature and the strength of the magnetic field. The size of the assembled nanowire networks ranged from tens of microns to millimeters. The electrical characteristics of the 3D nanowire networks were measured by regular current-voltage (I-V) measurements using a probe station with micropositioners. Nano-solders, when combined with assembling techniques, can be used to efficiently connect and join nanowires with low contact resistance, which are very well suited for sensor integration as well as nanoelectronic device fabrication.

Nanowire Electrodes for Advanced Lithium Batteries

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-27

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

Nanowire Electrodes for Advanced Lithium Batteries

Directory of Open Access Journals (Sweden)

Lei eHuang

2014-10-01

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

Nanowire Electrodes for Advanced Lithium Batteries

International Nuclear Information System (INIS)

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

2014-01-01

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

Position-controlled epitaxial III-V nanowires on silicon

Energy Technology Data Exchange (ETDEWEB)

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

2006-06-14

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

Position-controlled epitaxial III-V nanowires on silicon

International Nuclear Information System (INIS)

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

2006-01-01

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

AC surface photovoltage of indium phosphide nanowire networks

Energy Technology Data Exchange (ETDEWEB)

Lohn, Andrew J.; Kobayashi, Nobuhiko P. [California Univ., Santa Cruz, CA (United States). Baskin School of Engineering; California Univ., Santa Cruz, CA (US). Nanostructured Energy Conversion Technology and Research (NECTAR); NASA Ames Research Center, Moffett Field, CA (United States). Advanced Studies Laboratories

2012-06-15

Surface photovoltage is used to study the dynamics of photogenerated carriers which are transported through a highly interconnected three-dimensional network of indium phosphide nanowires. Through the nanowire network charge transport is possible over distances far in excess of the nanowire lengths. Surface photovoltage was measured within a region 10.5-14.5 mm from the focus of the illumination, which was chopped at a range of frequencies from 15 Hz to 30 kHz. Carrier dynamics were modeled by approximating the nanowire network as a thin film, then fitted to experiment suggesting diffusion of electrons and holes at approximately 75% of the bulk value in InP but with significantly reduced built-in fields, presumably due to screening by nanowire surfaces. (orig.)

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.

Biotemplated synthesis of PZT nanowires.

Science.gov (United States)

Cung, Kellye; Han, Booyeon J; Nguyen, Thanh D; Mao, Sheng; Yeh, Yao-Wen; Xu, Shiyou; Naik, Rajesh R; Poirier, Gerald; Yao, Nan; Purohit, Prashant K; McAlpine, Michael C

2013-01-01

Piezoelectric nanowires are an important class of smart materials for next-generation applications including energy harvesting, robotic actuation, and bioMEMS. Lead zirconate titanate (PZT), in particular, has attracted significant attention, owing to its superior electromechanical conversion performance. Yet, the ability to synthesize crystalline PZT nanowires with well-controlled properties remains a challenge. Applications of common nanosynthesis methods to PZT are hampered by issues such as slow kinetics, lack of suitable catalysts, and harsh reaction conditions. Here we report a versatile biomimetic method, in which biotemplates are used to define PZT nanostructures, allowing for rational control over composition and crystallinity. Specifically, stoichiometric PZT nanowires were synthesized using both polysaccharide (alginate) and bacteriophage templates. The wires possessed measured piezoelectric constants of up to 132 pm/V after poling, among the highest reported for PZT nanomaterials. Further, integrated devices can generate up to 0.820 μW/cm(2) of power. These results suggest that biotemplated piezoelectric nanowires are attractive candidates for stimuli-responsive nanosensors, adaptive nanoactuators, and nanoscale energy harvesters.

Semiconductor Nanowires: What's Next?

Energy Technology Data Exchange (ETDEWEB)

Yang, Peidong; Yan, Ruoxue; Fardy, Melissa

2010-04-28

In this perspective, we take a critical look at the research progress within the nanowire community for the past decade. We discuss issues on the discovery of fundamentally new phenomena versus performance benchmarking for many of the nanowire applications. We also notice that both the bottom-up and top-down approaches have played important roles in advancing our fundamental understanding of this new class of nanostructures. Finally we attempt to look into the future and offer our personal opinions on what the future trends will be in nanowire research.

Excitonic terahertz photoconductivity in intrinsic semiconductor nanowires

Science.gov (United States)

Yan, Jie-Yun

2018-06-01

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

Contact planarization of ensemble nanowires

Science.gov (United States)

Chia, A. C. E.; LaPierre, R. R.

2011-06-01

The viability of four organic polymers (S1808, SC200, SU8 and Cyclotene) as filling materials to achieve planarization of ensemble nanowire arrays is reported. Analysis of the porosity, surface roughness and thermal stability of each filling material was performed. Sonication was used as an effective method to remove the tops of the nanowires (NWs) to achieve complete planarization. Ensemble nanowire devices were fully fabricated and I-V measurements confirmed that Cyclotene effectively planarizes the NWs while still serving the role as an insulating layer between the top and bottom contacts. These processes and analysis can be easily implemented into future characterization and fabrication of ensemble NWs for optoelectronic device applications.

Plasmonic Waveguide-Integrated Nanowire Laser

DEFF Research Database (Denmark)

Bermudez-Urena, Esteban; Tutuncuoglu, Gozde; Cuerda, Javier

2017-01-01

Next-generation optoelectronic devices and photonic circuitry will have to incorporate on-chip compatible nanolaser sources. Semiconductor nanowire lasers have emerged as strong candidates for integrated systems with applications ranging from ultrasensitive sensing to data communication technolog......Next-generation optoelectronic devices and photonic circuitry will have to incorporate on-chip compatible nanolaser sources. Semiconductor nanowire lasers have emerged as strong candidates for integrated systems with applications ranging from ultrasensitive sensing to data communication...... technologies. Despite significant advances in their fundamental aspects, the integration within scalable photonic circuitry remains challenging. Here we report on the realization of hybrid photonic devices consisting of nanowire lasers integrated with wafer-scale lithographically designed V-groove plasmonic...

Reconfigurable Complementary Logic Circuits with Ambipolar Organic Transistors.

Science.gov (United States)

Yoo, Hocheon; Ghittorelli, Matteo; Smits, Edsger C P; Gelinck, Gerwin H; Lee, Han-Koo; Torricelli, Fabrizio; Kim, Jae-Joon

2016-10-20

Ambipolar organic electronics offer great potential for simple and low-cost fabrication of complementary logic circuits on large-area and mechanically flexible substrates. Ambipolar transistors are ideal candidates for the simple and low-cost development of complementary logic circuits since they can operate as n-type and p-type transistors. Nevertheless, the experimental demonstration of ambipolar organic complementary circuits is limited to inverters. The control of the transistor polarity is crucial for proper circuit operation. Novel gating techniques enable to control the transistor polarity but result in dramatically reduced performances. Here we show high-performance non-planar ambipolar organic transistors with electrical control of the polarity and orders of magnitude higher performances with respect to state-of-art split-gate ambipolar transistors. Electrically reconfigurable complementary logic gates based on ambipolar organic transistors are experimentally demonstrated, thus opening up new opportunities for ambipolar organic complementary electronics.