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Nanotechnology, IEEE Transactions on

Issue 4 • Date July 2009

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Displaying Results 1 - 24 of 24
  • Table of contents

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

    Page(s): C2
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  • Table of contents

    Page(s): 425 - 426
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  • Gravity-Assisted Seeding Control for 1-D Material Growth

    Page(s): 427 - 430
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    This letter presents a seeding control scheme by utilizing gravity force to form an agglomeration of molten Co seeds on a patterned inverted silicon nanopyramid. Nanometer sized molten Co seeds formed on a nonwettable inverted pyramid surface can roll along the inclination followed by aggregation to form a singular seed with the size depending on the pyramid size and the thickness of as-deposited Co film inside the pyramid. The proposed scheme allowing the formation of well-aligned catalytic seeds with manipulated size will promise the control growth of 1-D material for practical integrated microelectronic device fabrication. View full abstract»

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  • The Control on Size and Density of InAs QDs by Droplet Epitaxy (April 2009)

    Page(s): 431 - 436
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    We report on the ability to grow InAs quantum dots (QDs) by droplet epitaxy (DE) using solid-source molecular beam epitaxy (MBE). In particular, the control of the size and density of InAs QDs at near room temperatures are achieved as a function of substrate temperature and crystallization condition. For a typical range of QD density ( ~109 to 1010 cm-2), the growth window is revealed to be fairly narrow ( ~20degC). In droplets are extremely sensitive to surface diffusion and arsenic background pressure even at near room temperatures. As a result, a very careful fabrication procedure is required to crystallize In droplets in order to fabricate desired shape of InAs QDs. For this purpose, we developed a double-step crystallization process, in which As background recovery and high-temperature crystallization are introduced. In addition, the results by DE are compared with QDs fabricated by Stranski-Krastanow (S-K) growth approach in terms of size and density. The results can find applications in optoelectronics as the fabrication of QDs by DE approach has more flexibility over S-K approach, i.e., more freedom of size and density control. View full abstract»

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  • Phase Transformation and Magnetic Hardening in Isolated FePt Nanoparticles

    Page(s): 437 - 443
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB) |  | HTML iconHTML  

    Isolated monodisperse L10 FePt nanoparticles coated by carbon were obtained by adding enough surfactants that decomposed into carbon after the chemical synthesis and postannealing of the A1 FePt nanoparticles. The effect of isolation between FePt nanoparticles on the phase transition temperature and magnetic properties has been studied systematically by thermal, magnetic, and structural characterizations and analyses. It was found that the A1 to L10 phase transition temperature is dependent sensitively on the amount of isolation medium. The transition temperature shift reaches 150-200degC from nonisolated particle assemblies to completely isolated particles, which may be attributed to the high activation energy of the phase transformation for the isolated particles. View full abstract»

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  • A Comparative Study of Carrier Transport for Overlapped and Nonoverlapped Multiple-Gate SOI MOSFETs

    Page(s): 444 - 448
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB) |  | HTML iconHTML  

    This paper provides a comparative study of carrier transport characteristics for multiple-gate silicon-on-insulator MOSFETs with and without the nonoverlapped source/drain structure. For the overlapped devices, we observed Boltzmann law in subthreshold characteristics and phonon-limited behavior in the inversion regime. For the nonoverlapped devices, however, we found insensitive temperature dependence for drain current in both subthreshold and inversion regimes. Our low-temperature measurements indicate that the intersubband scattering is the dominant carrier transport mechanism for narrow overlapped multigate field-effect transistors(MuGFETs). For the nonoverlapped MuGFETs, the voltage-controlled potential barriers in the nonoverlapped regions may give rise to the weak localization effect (conductance reduction) and the quantum interference fluctuations. View full abstract»

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  • Shaping Nanoelectrodes for High-Precision Dielectrophoretic Assembly of Carbon Nanotubes

    Page(s): 449 - 456
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1058 KB) |  | HTML iconHTML  

    To achieve high-precision dielectrophoretic (DEP) assembly of carbon nanotubes (CNTs) for nanoelectronic circuits and nanoelectromechanical systems (NEMS), a technique is investigated both theoretically and experimentally for shaping the local geometries of nanoelectrodes to control the electrohydrodynamic behavior of CNTs. Motion trajectories and positions of CNTs assembled on electrodes are predicted based on calculated DEP forces and torques. Both simulation and experimental results show that the geometries of two opposing electrodes significantly affect the precision and robustness with which CNTs can be deposited. Experimental investigation of an electrode array demonstrates that the spacing between neighboring electrode pairs should be larger than twice the width of electrodes to avoid overlapping electric fields and unstable DEP forces; otherwise, unequally distributed electric fields and DEP forces induce a significant number of assembly failures in the array. View full abstract»

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  • Automatic Analysis of Conjugated Polyelectrolyte–DNA Interactions Based on Sequential Analysis of AFM Imaging

    Page(s): 457 - 462
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (402 KB) |  | HTML iconHTML  

    Biomolecular image analysis creates new perspectives for scientific communities such as chemists, biophysicists, and computer scientists. Data processing changes our understanding about the manner in which biosensing devices function. This information can be used for biological and medical applications alike. A key challenge in the field of nanoscience is to gain an understanding of conjugated polyelectrolyte (CPEs) aggregation with respect to biomolecules such as DNA and/or proteins. Polymers such as CPE are water-soluble multicomponent molecules that combine semiconductor and light harvesting properties and they have been successfully used for fluorescence sensing. We have developed a software tool capable of reconstructing topological images in sequential fashion to provide precise statistical data about the aggregations and composition of deposited material. Atomic force microscopy has been used to analyze various processes of polymer-DNA formation. In this paper, we present a new approach to image analysis and processing of atomic force microscopy (AFM) data. The software presented is based on multistage thresholding and mathematical morphology methods and can be used for any other topological images. View full abstract»

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  • Manipulation and Observation of Carbon Nanotubes in Water Under an Optical Microscope Using a Microfluidic Chip

    Page(s): 463 - 468
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (657 KB) |  | HTML iconHTML  

    We successfully manipulated and observed carbon nanotubes (CNTs) in water, under an optical microscope. We employed a quenching observation method, where the intensity of fluorescent reagents around CNTs is decreased due to energy transfer. By this method, CNTs can be observed continuously for a long time by adding a new fluorescent reagent after fluorescence photobleaching. However, we must adjust the density of the fluorescent reagent around CNTs, which is extremely difficult to control. Thus, we built a fluorescent reagent supply system in a microfluidic chip. We found that polydimethylsiloxane with a porous structure could absorb the fluorescent reagent as a carrier and supply the reagent at a high and constant density for a long time. In experiments, using a microstirrer, we mixed two fluids uniformly, and succeeded in controlling the density of the fluorescent reagent. In addition, we applied dielectrophoretic (DEP) force for trapping the CNTs. The electrode material was indium-tin oxide, which is suitable for manipulation and observation of CNTs under an optical microscope because of its high conductive properties and good transparency. In these experiments, we trapped CNTs by DEP and observed CNTs by quenching on the chip, and confirmed that the fluorescent image of the CNTs was clearer than their bright-field images. View full abstract»

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  • Vertical Carbon Nanotube Devices With Nanoscale Lengths Controlled Without Lithography

    Page(s): 469 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (647 KB) |  | HTML iconHTML  

    Vertical single-walled carbon nanotubes (v-SWCNTs) are synthesized within highly ordered porous anodic alumina (PAA) templates supported on Si substrates. A process for obtaining thin-film PAA with long-range ordered nanopores is presented in this paper. Each nanopore contains at most one v-SWCNT that is supported by a dielectric and addressed by electrochemically formed Pd nanowire source contacts and evaporated Pd drain contacts. Characteristics of these completely vertical, two-terminal nanotube devices are presented. Control of the v-SWCNT length is demonstrated using a straightforward etching process with lengths of less than 100 nm achieved without the need for complex/expensive lithography. This effective nanoscale length control of highly ordered v-SWCNTs provides a practical basis for the realization of CNT-based nanoelectronics. View full abstract»

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  • Effective Damping Contribution From Micromagnetic Modeling in a Spin-Transfer-Driven Ferromagnetic Resonance

    Page(s): 477 - 481
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Spin-transfer-driven ferromagnetic resonance is theoretically analyzed in a Py/Cu/Py spin valve with elliptical cross-sectional area (90 nm times 30 nm) by means of macrospin and micromagnetic simulations. An additional damping contribution to the Gilbert parameter is obtained when the spatial dependence of the magnetization is taken into account. These results are used to quantitatively explain the large value of the damping parameter found in the experiments by Sankey et al. [Phys. Rev. Lett. 96, 227601 (2006)]. The dependence of this additional damping on the dc bias is also studied, and the strength of the nonuniformities is quantified by means of a phenomenological expression. View full abstract»

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  • A Novel High-Speed Multiplexing IC Based on Resonant Tunneling Diodes

    Page(s): 482 - 486
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    A new multiplexing IC based on the resonant tunneling diode (RTD) is proposed. The unique negative differential resistance characteristics arising from quantum effects of the RTD enable us to develop a new functional low-power digital circuit. The proposed multiplexing IC consists of two current-mode-logic monostable-bistable transition logic elements (CML-MOBILEs) based on the RTD and a low-power selector circuit block. The proposed circuit has been fabricated by using an InP RTD/ heterojunction bipolar transistor monolithic microwave integrated circuit technology. The multiplexing operation of the fabricated quantum effect IC has been confirmed up to 45 Gb/s for the first time as a monolithic technology based on the quantum effect devices. The dc power consumption is only 23 mW, which is found to be one-fourth of the current state-of-the-art conventional transistor-based multiplexing IC. View full abstract»

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  • How to Control AFM Nanoxerography for the Templated Monolayered Assembly of 2 nm Colloidal Gold Nanoparticles

    Page(s): 487 - 491
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (415 KB) |  | HTML iconHTML  

    This paper reports on the directed monolayered assembly of 2 nm colloidal gold nanoparticles onto charge patterns written by atomic force microscopy (AFM) on poly(methylmethacrylate) thin films with a sub-100-nm spatial resolution. The impact of key experimental parameters (surface potential of charge patterns, immersion time in the colloidal solution, nanoparticle concentration, rinsing time) on the nanoparticle assembly was quantified for the first time. This study reveals that the high level of control of this so-called AFM nanoxerography process will allow one to construct promising colloid-based devices integrating localized nanoparticle monolayers of desired density. View full abstract»

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  • Fabrication and Characteristics of Self-Aligned Dual-Gate Single-Electron Transistors

    Page(s): 492 - 497
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (818 KB) |  | HTML iconHTML  

    Single-electron transistors that have electrical tunneling barriers are fabricated, and Coulomb oscillation peaks and negative differential transconductance are observed at room temperature (300 K). Operation characteristics and multioscillation peaks are further investigated at low temperature (80 K). The period of Coulomb oscillation is 2.3 V due to an ultrasmall control gate capacitance, and oscillation peaks are shifted through the side gate bias, which is explained by the derived stability plot for dual-gate structures. Even with the side gates electrically floating, the device still operates as a single-electron transistor since the p-n junction barrier plays a role of tunneling barrier. In addition, by changing the bias condition, double dots are formed along the channel and peak splitting is observed. View full abstract»

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  • Wafer-Scale Growth and Transfer of Aligned Single-Walled Carbon Nanotubes

    Page(s): 498 - 504
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1472 KB) |  | HTML iconHTML  

    Experimental demonstration of wafer-scale growth of well-aligned, dense, single-walled carbon nanotubes on 4" ST-cut quartz wafers is presented. We developed a new carbon nanotube (CNT) wafer-scale growth process. This process allows quartz wafers to be heated to the CNT growth temperature of 865degC through the alpha-beta phase transformation temperature of quartz (573degC) without wafer fracture. We also demonstrate wafer-scale CNT transfer to transfer these aligned CNTs from quartz wafers to silicon wafers. The CNT transfer process preserves CNT density and alignment. Carbon nanotube FETs fabricated using these transferred CNTs exhibit high yield. Wafer-scale growth and wafer-scale transfer of aligned CNTs enable carbon nanotube very large-scale integration circuits and their large-scale integration with silicon CMOS. View full abstract»

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  • Switching Energy of Ferromagnetic Logic Bits

    Page(s): 505 - 514
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    Power dissipation in switching devices is believed to be the single most important roadblock to the continued downscaling of electronic circuits. There is a lot of experimental effort at this time to implement switching circuits based on magnets and it is important to establish power requirements for such circuits and their dependence on various parameters. This paper analyzes switching energy that is dissipated in the switching process of single-domain ferromagnets used as cascadable logic bits. We obtain generic results that can be used for comparison with alternative technologies or guide the design of magnet-based switching circuits. Two central results are established. One is that the switching energy drops significantly if the ramp time of an external pulse exceeds a critical time. This drop occurs more rapidly than what is normally expected of adiabatic switching for a capacitor. The other result is that under the switching scheme that allows for logic operations, the switching energy can be described by a single equation in both fast and slow limits. Furthermore, these generic results are used to discuss the practical consideration such as dissipation versus speed, increasing the switching speed and scaling. It is further explained that nanomagnets can have scaling laws similar to CMOS technology. View full abstract»

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  • A Current Cycle Feedback Iterative Learning Control Approach for AFM Imaging

    Page(s): 515 - 527
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB) |  | HTML iconHTML  

    In this paper, we proposed a novel current cycle feedback (CCF) iterative learning control (ILC) approach to achieve high-speed imaging on atomic force microscope (AFM). AFM imaging requires precision positioning of the AFM probe relative to the sample in 3-D (x- y-z). It has been demonstrated that, with advanced control techniques such as the inversion-based iterative control (IIC), precision positioning of the AFM probe in the lateral (x- y) scanning can be successfully achieved. Precision positioning of the probe in the vertical z-axis direction, however, is still challenging because the issues such as the sample topography are unknown, in general; the probe-sample interaction is complicated, and the probe-sample position is sensitive to the probe-sample interaction. The main contribution of this paper is the development of the CCF-ILC approach for the AFM z-axis control, which decouples the robustness of the feedback control from the precision tracking of the feedforward control. Particularly, the proposed CCF-ILC controller design utilizes the recently developed robust inversion technique to minimize the model uncertainty effect on the feedforward control and to remove the causality constraints in other CCF-ILC approaches. It is shown that the iterative law converges and attains a bounded tracking error upon noise and disturbances. The proposed method is illustrated through experimental implementation, and the experimental results show an increase of eight times faster imaging speed for contact-mode imaging. View full abstract»

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  • Uniaxial Strain Effects on the Performance of a Ballistic Top Gate Graphene Nanoribbon on Insulator Transistor

    Page(s): 528 - 534
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    The effects of uniaxial strain on the bandgap and performance of a top gate graphene nanoribbon (GNR) on insulator transistor are studied using pi-orbital basis 3-D ballistic quantum simulation. The bandgap variation with strain shows zigzag pattern for the three families of nanoribbon. The variation is linear between two turning points and has almost equal magnitude of gradient for all the families. The ON-state and the off-state currents reduce and the ON/OFF current ratio increases with the type of strain that results in larger bandgap. The variation of off current and ON/OFF current ratio is exponential, and that of on current is linear with strain and is independent of the type of strain applied. The intrinsic switching delay reduces and the intrinsic cutoff frequency increases with the type of strain that results in smaller bandgap. While the off -state current and the on/off current ratio improve with strain, the on-state current and switching performance degrade, and vice versa. Therefore, careful tradeoff should be considered in strain engineering of GNR transistors. View full abstract»

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  • Single-Electron Device With Si Nanodot Array and Multiple Input Gates

    Page(s): 535 - 541
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    We have developed a flexible-logic-gate single-electron device (SED) with an array of nanodots. Although the small size of SEDs is highly advantageous, the size of the nanodots inevitably fluctuates, which causes variations in device characteristics. This variability can be eliminated and high device functionality can be obtained by exploiting the oscillatory characteristics and multigate capability of SEDs. We fabricated, on a silicon-on-insulator wafer, a Si nanodot array device with two input gates and a control gate and investigated its basic operation characteristics experimentally. The device was demonstrated to operate as a logic gate providing six important logic functions ( and, or, nand, nor, xor, and xnor), which are obtained by adjusting the control-gate voltage. View full abstract»

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  • On the Applicability of Single-Walled Carbon Nanotubes as VLSI Interconnects

    Page(s): 542 - 559
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2003 KB) |  | HTML iconHTML  

    This paper presents a comprehensive study of the applicability of single-walled carbon nanotubes (SWCNTs) as interconnects in nanoscale integrated circuits. A detailed analysis of SWCNT interconnect resistance (considering its dependence on all physical parameters, as well as factors affecting the contact resistance), the first full 3-D capacitance simulations of SWCNT bundles for realistic very large scale integration (VLSI) interconnect dimensions, and a quantitative evaluation of the importance of inductive effects in SWCNT interconnects are presented. The applicability of carbon nanotube (CNT) based vias (vertical interconnects)-the most realizable CNT interconnects in the current state of the art-is addressed for the first time. It is shown that CNT interconnects can provide 30%-40% improvement in the delay of millimeter-long global interconnects. The applicability of CNT monolayers as local interconnects is found to be much more limited than that reported in the prior literature. Dense CNT bundle global interconnects are shown to offer a 4times reduction in power dissipation while achieving the same delay as optimally buffered Cu interconnects at the 22 nm node. This power saving increases to 8times at the 14 nm node. Furthermore, 3-D finite-element electrothermal simulations show that CNT bundles used as vias in between Cu metal layers can provide large improvement in metal interconnect lifetime by lowering the temperature of the hottest interconnects. View full abstract»

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  • Correction to "Minimizing Scanning Errors in Piezoelectric Stack-Actuated Nanopositioning Platforms" [Jan 08 79-90]

    Page(s): 560
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    In the above titled paper (ibid., vol. 7, no. 1, pp. 79-80, Jan. 08), the figures appearing in the published version do not have the intended axis labels. The correct labels are provided here. View full abstract»

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  • IEEE Transactions on Nanotechnology information for authors

    Page(s): C3
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    Page(s): C4
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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.

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