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Nanotechnology, IEEE Transactions on

Issue 4 • Date July 2008

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Displaying Results 1 - 25 of 26
  • Table of contents

    Page(s): C1
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    Freely Available from IEEE
  • IEEE Transactions on Nanotechnology publication information

    Page(s): C2
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    Freely Available from IEEE
  • A Nanogripper Employing Aligned Multiwall Carbon Nanotubes

    Page(s): 389 - 393
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (417 KB) |  | HTML iconHTML  

    Nanogripper structures using aligned multiwall carbon nanotubes (MWCNTs) are demonstrated and their electromechanical properties have been studied in this paper. The balance of electrostatic force, together with elastostatic force and van der Waals force determines the driving conditions. A triode structure drastically reduces the bias between two moving parts, which consist of MWCNTs. Low bias also enables low power consumption as well as the reduction of electrical damage to an object. The moving parts can keep the same state without any applied biases after bending and connection. This also enables power saving during driving. The device can be a base structure for various nanorobotic or other nanoelectromechanical devices. View full abstract»

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  • Two-Layer Nanocoatings in Long-Period Fiber Gratings for Improved Sensitivity of Humidity Sensors

    Page(s): 394 - 400
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    A relative humidity sensor based on the deposition of electrostatic self-assembled alumina ( Al2O3) and poly(sodium 4-styrenesulfonate) on the cladding of a long-period fiber grating (LPFG) has been designed. The sensitive material has a lower refractive index than that of the fiber cladding, which limits the sensitivity of the LPFG response. In order to enhance its sensitivity, a previous high refractive index coating has been deposited. The overlay thickness is of the order of magnitude of the light wavelength used to interrogate the sensor. A theoretical model of multilayer cylindrical waveguides based on coupled-mode theory has been used to predict the phenomenon. Experimentally, an increased wavelength shift of the attenuation bands (75%) was obtained during the fabrication of the sensor, and, what is more important, the sensitivity was improved by a ratio of almost four. The proposed method improves the performance of LPFG-based sensors characterized by overlays of low refractive index. View full abstract»

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  • Scaling and Optimization of MOS Optical Modulators in Nanometer SOI Waveguides

    Page(s): 401 - 408
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (839 KB) |  | HTML iconHTML  

    In this paper, a very accurate model of optical modulators in silicon-on-insulator technology is developed and validated using experimental results reported in literature. Using an optimized nanometer MOS structure, a significant bandwidth increase (around 45%), length decrease (around four times), and power consumption reduction (three times) with respect to the state-of-the-art have been obtained. View full abstract»

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  • Structural and Magnetic Properties of Amorphous and Nanocrystalline CoFeSiB Thin Films

    Page(s): 409 - 411
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    This study examined the structural, magnetic, and transport properties of CoFeSiB films with various Co compositions. The main focus was on two samples, amorphous Co74Fe4Si14B8 and nanocrystalline Co78Fe2Si12B8 thin films. The results show that the amorphous film is a typical soft magnetic material, while the nanocrystalline film has a large saturation field. It is believed that in a nanocrystalline thin film, a large saturation field is caused by antiferromagnetic exchange at the boundary between the amorphous and nanocrystalline phases. View full abstract»

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  • Improvement of Electrical Properties of \hbox {Ba}_{{\bf 0.7}}\hbox {Sr}_{\bf 0.3}\hbox {TiO}_{\bf 3} Capacitors With an Inserted Nano-Cr Interlayer

    Page(s): 412 - 417
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (347 KB) |  | HTML iconHTML  

    The metal-insulator-metal (MIM) capacitors were prepared with Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) dielectric and Pt electrode. The multilayer BST/Cr/BST was sputtered onto Pt/Ti/SiO2/Si substrate. The presence of nano-Cr interlayer affects the electrical properties of the capacitors. The temperature coefficient of capacitance (TCC) of capacitors with 2 nm Cr is about 69% of that of capacitors without Cr. In a previous work, the formation of the TiO2 secondary phase was found after the BST/Cr/BST dielectrics were annealed at 1023 K in O2 atmosphere for 1 h. It is suggested that the nano-Cr interlayer as a catalyst leads to the TiO2 formation during the annealing in O2 atmosphere. The negative value of TCC of BST can be compensated by the positive TCC of TiO2, and the temperature stability in the dielectric constant can be realized for capacitors with nano-Cr interlayer. The voltage stability of BST is also improved with the insertion of nano-Cr interlayer, and the quadratic coefficient in voltage coefficient of capacitance (VCC) of Pt/BST/Cr(2 nm)/BST/Pt is about 30% of that of the BST capacitor without Cr. The effects of Cr thickness on TCC, VCC, dissipation factor, and leakage current density of Pt/BST/Cr/BST/Pt parallel plate capacitors are investigated. View full abstract»

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  • Anomalous Negative Bias Temperature Instability Degradation Induced by Source/Drain Bias in Nanoscale PMOS Devices

    Page(s): 418 - 421
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (110 KB) |  | HTML iconHTML  

    The effect of source/drain (S/D) bias on the negative bias temperature instability (NBTI) of pMOSFETs is studied. The anomalously enhanced NBTI under S/D bias conditions is observed, which cannot be explained by the conventional reaction-diffusion model. A new mechanism based on the enhanced interfacial dissociation of equivSi-H bonds induced by the energetic holes (the hole energy Eh is higher than the reaction activation energy Ea of equivSi-H bond dissociation) is proposed to address the observed degradation behaviors. Monte Carlo simulations are used to identify the validity of the new mechanism. View full abstract»

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  • Selective Intermixing of InAs/InGaAs/InP Quantum Dot Structure With Large Energy Band Gap Tuning

    Page(s): 422 - 426
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    Selective postgrowth band gap tuning of self-assembled InAs/InGaAs/InP quantum dot (QD) structures has been investigated. Very large band gap blueshift of over 158 meV of the InAs QD structure has been received through the intermixing by exposing the sample under argon plasma and followed by thermal annealing at 780 degC. Selective intermixing of the InAs QD structure has been studied by depositing a SiO2 mask layer on the sample for the intermixing. The largest selective band gap shift between the SiO2 covered and uncovered regions of the sample reaches 77 meV. This intermixing selectivity decreases when the annealing temperature is increased. This reduction in the intermixing selectivity is attributed to the enhanced QDs intermixing of the SiO2-masked samples because of the out diffusion of different elements from the InAs/InGaAs/InP QD structure into the SiO2 cover layer. Three different energy band gap shifts of an InAs/InGaAs/InP QD structure across the wafer have been received by this postgrowth selective intermixing. The selective band gap tuning paves a way for monolithic integration of passive and active optoelectronic devices in QD systems. View full abstract»

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  • Design Consideration of Bulk FinFETs Devices With \hbox {\rm n}^{+}\hbox {/}^{}\hbox {\rm p}^{+}\hbox {/}^{}\hbox {\rm n}^{{+}} Gate and \hbox {\rm p}^{+}\hbox {/}^{}\hbox {\rm n}^{{+}} Gate for Sub-50-nm DRAM Cell Transistors

    Page(s): 427 - 433
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1144 KB) |  | HTML iconHTML  

    In this paper, design considerations for the n+/p+/n+ gate bulk FinFET in sub-50-nm technology nodes is extensively studied through 3D device simulation. For the comparison of electrical characteristics of n+/p+/n+ gate bulk FinFET, the electrical characteristics of p+/n+ gate bulk FinFET were also studied. The electrical characteristics of devices with different n+ gate lengths (L s) and fin body widths ( W fin) were compared in terms of threshold voltage ( V th), on -current (I ON), off -state current (I OFF), subthreshold swing (SS), and drain-induced barrier lowering (DIBL). In this study, with a limit of gate length ( L g les 50 nm) and a fin body width ( W fin les 30 nm), bulk FinFETs were designed to achieve an off-current less than 1 fA. Two-nanometer-thick SiO2 layers were inserted between an n+ gate and a p+ gate of the device with n+/p+/n+ gate. Then, the electrical characteristics of the device were studied. Specifically, the source/drain to gate overlap length (L ov)s were changed for both the bulk FinFETs with n+/p+/n+ gate and the device with a p+ gate. Then, the electrical characteristics of both devices were compared. View full abstract»

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  • Effect of Process Variation on Field Emission Characteristics in Surface-Conduction Electron Emitters

    Page(s): 434 - 439
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (649 KB) |  | HTML iconHTML  

    In this paper, we explore the effect of process variation on field emission characteristics in surface-conduction electron emitters. The structure of Pd thin-film emitter is fabricated on the substrate and the nanometer scale gap is formed by the focused ion beam technique. Different shapes of nanogaps due to the process variations are investigated by the experiment and three-dimensional Maxwell particle-in-cell simulation. Four deformation structures are examined, and it is found that the type 1 exhibits high emission efficiency due to a stronger electric field around the apex and larger emission current among structures. The electron emission current is dependent upon the angle of inclination of surface. Hydrogen plasma treatment is also used to increase the edge roughness of the nanogap and thereby dramatically improve the field emission characteristics. For the nanogap with a separation of 90 nm, the turn-on voltage significantly reduces from 60 to 20 V after the hydrogen plasma treatment. View full abstract»

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  • Smart Universal Multiple-Valued Logic Gates by Transferring Single Electrons

    Page(s): 440 - 450
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (409 KB) |  | HTML iconHTML  

    This paper proposes smart universal multiple-valued (MV) logic gates by transferring single electrons (SEs). The logic gates are based on mosfet based SE turnstiles that can accurately transfer SEs with high speed at high temperature. The number of electrons transferred per cycle by the SE turnstile is a quantized function of its gate voltage, and this characteristic is fully exploited to compactly finish MV logic operations. First, we build arbitrary MV literal gates by using pairs of SE turnstiles. Then, we propose universal MV logic-to-value conversion gates and MV analog-digital conversion circuits. We propose a SPICE model to describe the behavior of the mosfet based SE turnstile. We simulate the performances of the proposed gates. The MV logic gates have small number of transistors and low power dissipations. View full abstract»

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  • Strong Spatial Dependence of Electron Velocity, Density, and Intervalley Scattering in an Asymmetric Nanodevice in the Nonlinear Transport Regime

    Page(s): 451 - 457
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (499 KB) |  | HTML iconHTML  

    Using a 2-D ensemble Monte Carlo method, we have studied the electron transport in a self-switching device, which is a semiconductor rectifier consisting of an asymmetric nanochannel. Apart from obtaining a good agreement between the theoretical and experimental current-voltage characteristics, the focus is to study the detailed electron transport inside the nanochannel. Our simulations reveal a drastic spatial dependence of the electron velocity, density, and intervalley scatterings along the channel direction because of the strongly nonlinear transport combined with the asymmetric device geometry. We show that pronounced negative differential electron velocity actually occurs in certain regions inside the channel and changes under different bias conditions. Electron intervalley transfer is also found to depend strongly on the sign of the bias voltage as well as the spatial location in the channel. Moreover, we find that it can take a distance of up to 1 mum for the hot electrons to relax their energy after passing through the nanochannel at high biases. The implications on device operating speed and integration are discussed. View full abstract»

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  • Enhanced Subthreshold Slopes in Large Diameter Single Wall Carbon Nanotube Field Effect Transistors

    Page(s): 458 - 462
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (515 KB) |  | HTML iconHTML  

    The performance of single wall carbon nanotube field effect transistors (SWNT FETs) is greatly affected by the quality of its contacts. The presence of Schottky barriers imposes a strong scaling of the gate dielectric thickness. Here, we employ large diameter SWNTs in order to fabricate ohmically contacted FETs when a lower work function but higher adhesion strength metal such as Cr is used. A subthreshold slope as low as 113 mV/dec is obtained even when employing a thick, 200 nm SiO2 dielectric. The result is examined in light of the positive effects of exposure to air and underlines the possibility for less stringent device fabrication techniques. View full abstract»

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  • Recording Physics, Design Considerations, and Fabrication of Nanoscale Bit-Patterned Media

    Page(s): 463 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1017 KB) |  | HTML iconHTML  

    Recording physics, design considerations, and fabrication of bit-patterned magnetic medium for next generation data storage systems is presented. (Co/Pd)N magnetic multilayers are evaluated as candidates for bit-patterned medium recording layer materials for their high and easily tunable magnetic anisotropy. The optimized patterned multilayers used in this study had coercivities in excess of 12-14 kOe. Bit patterning was accomplished using ion-beam proximity printing, a high-throughput direct write lithography where a large array of ion beamlets shaped by a stencil mask is used to write an arbitrary device pattern. It is found that the nature of magnetization reversal strongly depends on bit edge imperfections and is likely to contribute to switching field distribution. View full abstract»

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  • Limitations of Au Particle Nanoassembly Using Dielectrophoretic Force—A Parametric Experimental and Theoretical Study

    Page(s): 477 - 479
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    When a gold colloidal suspension is subjected to ac electric field, ldquogold pearl chainsrdquo will form due to the dielectrophoretic (DEP) force. Our latest experiments show that the formation rate of gold pearl chains, which tends to zero at high and low frequency limits and has a maximum at a narrow mid range of frequency, is dependent on the applied field frequency. This letter analyzes the frequency-dependent DEP manipulation of gold colloid suspensions using the protoplast model. Simulated results show that the relationship curve between the frequency of applied field and the velocity of gold colloids motion due to DEP agrees with our experimental observations. In addition, the orders of magnitude of the velocity due to various effects in our experimental system, such as DEP force, Brownian motion, gravity, and fluid flows induced by electric field, were also estimated. The result implies that the DEP-based manipulation of less than 2 nm gold colloids is extremely difficult to be controlled. View full abstract»

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  • Nonvolatile Memory via Spin Polaron Formation

    Page(s): 480 - 483
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (134 KB) |  | HTML iconHTML  

    A nonvolatile memory is explored theoretically by utilizing the magnetic exchange interaction between localized holes and an adjacent ferromagnetic (FM) material. The active device consists of a buried semiconductor quantum dot (QD) and an FM insulating layer that share an interface. The hole population in the QD is controlled by particle transfer with a reservoir of itinerant holes over a permeable barrier. A theoretical model based on the free energy calculation demonstrates the existence of a bistable state through the mechanism of a collective spin polaron, whose formation and dissolution can be manipulated electrically via a gate bias pulse. The parameter space window suitable for bistability is examined along with the conditions that support maximum nonvolatility. The limitation of QD size scaling is analyzed in terms of the bit retention time. View full abstract»

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  • Quantum Boolean Circuits are 1-Testable

    Page(s): 484 - 492
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (455 KB) |  | HTML iconHTML  

    Recently, a systematic procedure was proposed to derive a minimum input quantum circuit for any given classical logic with the generalized quantum Toffoli gate, which is universal in Boolean logic. Since quantum Boolean circuits are reversible, we can apply this property to build quantum iterative logic array (QILA). QILA can be easily tested in constant time (C-testable) if stuck-at fault model is assumed. In this paper, we use Hadamard and general controlled-controlled not gates to make QILA 1-testable. That is, for any quantum Boolean circuit, the number of test patterns is independent of both the size of the array and the length of the inputs. View full abstract»

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  • Controlled Assembly and Dispersion of Strain-Induced InGaAs/GaAs Nanotubes

    Page(s): 493 - 495
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB) |  | HTML iconHTML  

    Group III-V semiconductor nanotubes (SNTs) are formed when strained planar bilayers are released from the substrate. Compared to other nanotechnology building blocks, one of the main advantages of SNTs is the capability of precise positioning due to the top-down fabrication approach. In this letter, we demonstrate large-area assembly of ordered arrays of InxGa1-xAs/GaAs nanotubes and the dispersion of their freestanding form into solution and onto foreign substrates. In addition, we systematically investigate the crystal orientation dependence of rolling behavior using a wheel configuration, which serves as a guide for assembly homogeneity. Theoretical and experimental evaluations of tube diameters are also discussed. View full abstract»

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  • Chalcogenide-Nanowire-Based Phase Change Memory

    Page(s): 496 - 502
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (471 KB) |  | HTML iconHTML  

    We report fabrication of phase change random access memory (PRAM) using nanowires (NWs) of GeTe and In2Se3. NWs were grown by a vapor-liquid-solid technique and ranged from 40 to 80 nm in diameter and several micrometers long. A dynamic switching ratio (on/off ratio) of 2200 and 2 times 105 was realized for GeTe and indium selenide devices, respectively. The programming power for the RESET operation is only tens of microwatts compared to the milliwatt power levels required by the conventional thin-film-based PRAM. View full abstract»

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  • The Hybridization of CdSe/ZnS Quantum Dot on InGaN Light-Emitting Diodes for Color Conversion

    Page(s): 503 - 507
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (686 KB) |  | HTML iconHTML  

    We have demonstrated the fabrication and characterization of hybrid CdSe/ZnS quantum dot (QD)-InGaN blue LEDs. The chemically synthesized red light (lambda = 623 nm) QD solutions with different concentrations were dropped onto the blue InGaN LEDs with an emission peak of 453 nm and the turn-on voltage of 2.6 V. In this configuration, the CdSe/ZnS core/shell QDs played the role of a color-conversion center. It was clearly observed that the emission intensity from QDs was increased with increasing QD concentration. With a QD concentration of 10 mg/ml in toluene was incorporated, the ratio of emission intensity of QDs to that of InGaN quantum wells reached 0.17, whereas the Commission Internationale de lpsilaEclairage (CIE) chromaticity coordinates greatly shifted to (0.29, 0.14). From the spatial mapping of electroluminescence spectra, the decrease of the intensity of E QW seems to be faster than that of E QD, which suggests that the QD film thickness may be thicker in the edge of the surface of InGaN chip. There will, therefore, convert higher proportion of blue light to red light. Also, the resin-encapsulated hybrid LEDs have a divergence angle (the full angle at 1/e 2 intensity) of about 20deg as the device is operated at 10 mA. Furthermore, under the injection current of 20 mA and room temperature, this device can be operated for more than 1000 h without any obvious degradation. From our results, it can be proven that the synthesized QDs are promising nanophosphors for color-conversion applications of solid-state LEDs. However, to more efficiently convert the blue light to red light, a denser QD solution with higher quantum yield must be utilized. View full abstract»

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  • Engineering Multiwalled Carbon Nanotubes Inside a Transmission Electron Microscope Using Nanorobotic Manipulation

    Page(s): 508 - 517
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1475 KB) |  | HTML iconHTML  

    This paper provides a review of recent experimental techniques developed for shell engineering individual multiwalled carbon nanotubes (MWNTs). Basic processes for the nanorobotic manipulation of MWNTs inside a transmission electron microscope are investigated. MWNTs, bamboo-structured carbon nanotubes (CNTs), Cu-filled CNTs, and CNTs with quantum dots attached are used as test structures for manipulation. Picking is realized using van der Waals forces, ldquostickyrdquo probes, electron-beam-induced deposition, and electric breakdown. Cap opening and shell shortening are presented using field emission current. Controlled peeling and thinning of the shells of MWNTs are achieved by electric breakdown, and changes in MWNT structures are correlated with electrical measurements. These processes are fundamental for the characterization of nanoscale materials, the structuring of nanosized building blocks, and the prototyping of nanoelectromechanical systems. View full abstract»

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  • Order form for reprints

    Page(s): 518
    Save to Project icon | Request Permissions | PDF file iconPDF (353 KB)  
    Freely Available from IEEE
  • IEEE copyright form

    Page(s): 519 - 520
    Save to Project icon | Request Permissions | PDF file iconPDF (1065 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Nanotechnology Information for authors

    Page(s): C3
    Save to Project icon | Request Permissions | PDF file iconPDF (34 KB)  
    Freely Available from IEEE

Aims & Scope

The IEEE Transactions on Nanotechnology is devoted to the publication of manuscripts of archival value in the general area of nanotechnology, which is rapidly emerging as one of the fastest growing and most promising new technological developments for the next generation and beyond.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Fabrizio Lombardi
Dept. of ECE
Northeastern Univ.