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Nanotechnology, 2005. 5th IEEE Conference on

Date 11-15 July 2005

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Displaying Results 1 - 25 of 237
  • Molecular mechanics and molecular electronics

    Publication Year: 2005
    Cited by:  Papers (1)
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    Electronic devices containing molecules as either passive or active (switching) components present the opportunity for scaling electronic circuitry down to near-molecular dimensions. In this paper the kinetic and thermodynamic properties of bistable molecular mechanical switches known as catenanes and rotaxanes are discussed. A defect-tolerant, binary tree demultiplexer architecture using Order log2N submicron (lithographically patterned) wires to address TV nanowires are developed. Apart from traditional applications of memory, logic, and routing, new opportunities that include actuation, sensing, energy management, and possibly even peptide sequencing are enabled by these nanofabrication approaches. View full abstract»

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  • Nanobiotechnology: is there a Rosetta stone to translate biology to technology?

    Publication Year: 2005
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    The relationship between nanoscience and nanotechnology is discussed in this paper. Nanobiotechnology is aimed at the molecular design of interfaces for improved medical devices and diagnostics. Medical device implants, and the biomaterials that comprise them, are measured on macro scales (centimeters). Yet the biocompatibility of such devices may be dictated by phenomena best described at nanometer dimensions. Biological data on the in vivo healing responses of mammals to matricellular proteins such as osteopontin, thrombospondin 2 and SPARC with nonspecific protein adsorption is presented. The method including protein orientation (assembly) and type I collagen used to deliver signals along with their strategies is presented. Modern surface analysis techniques shows the complexity of a functional nanobiointerface. View full abstract»

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  • DNA assembly of component arrays for nanoscale electronics

    Publication Year: 2005 , Page(s): 738 - 741 vol. 2
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    A method for assembling arrays of components in programmable 2D arrangements with nanometer-scale precision is needed for the manufacture of high density nanoelectronic circuitry. We discuss the programmed self-assembly based on in situ hybridization of DNA-functionalized components to a pre-assembled 2D DNA scaffolding on a surface. We show that arrays of prototype electronic components composed of Au nanoparticles and nanowires can be assembled on a surface with high precision. This approach is broadly applicable to the manufacture of nanoscale integrated circuits for logic, memory, sensing, and other applications. View full abstract»

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  • Self-assembled nanowire-on-insulator (SANOI) for nano-chip technology

    Publication Year: 2005 , Page(s): 742 - 745 vol. 2
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    One-dimensional semiconducting nanowires (Si or Ge) directly synthesized on insulator layer by chemical method provide a viable technology analogous to silicon-on-insulator (SOI) and germanium-on-insulator (GOI), yet presenting much better chip design/integration flexibility, structural scalability, and cost-effectiveness. The new technology, called self-assembled nanowire-on-insulator (SANOI), illustrates a good example of how bottom-up nanotechnology based on inexpensive chemistry may provide solution to some of the most daunting challenges in the conventional silicon CMOS scaling. View full abstract»

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  • Effects of dimensional scaling on the electronic transport properties of silicon nanofilms and nanowires

    Publication Year: 2005 , Page(s): 746 - 749 vol. 2
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    A detailed investigation focused upon evaluating the effects of dimensional cross-sectional nanoscaling of silicon features on the electronic transport properties is presented. The feature dimensions ranged from ∼200 nm down to ∼10 nm. This range represents transition region from bulk properties towards the onset of quantization. The structures were fabricated on silicon-on-insulator using interferometric lithography, reactive-ion-etching and thermal oxidation methods. In order to investigate the optical and electronic properties, the nanostructures were configured in a two terminal test device configuration. Characterization methods included; dark and illuminated steady-state DC measurements and optically pulsed transient time response measurements using a modified version of the Haynes-Shockley experiment for evaluating the carrier mobility as a function of scaling the feature cross-section. Results showed that the total carrier drift-diffusion dependent conduction increases as the feature cross-sectional dimensions are reduced from ∼200 nm to ∼10 nm due to carrier confinement effects and clear differences between 1D (nanofilms) versus 2D (nanowires) scaling effects are observed. View full abstract»

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  • Transport properties of ultra thin oxide gated Si SET near room temperature

    Publication Year: 2005 , Page(s): 750 - 753 vol. 2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (994 KB) |  | HTML iconHTML  

    We have fabricated ultrathin oxide (thickness) of ∼6 nm gated silicon transistors with a point-contact junction of ∼20 nm thick, and 20 nm wide to explore single electron charging effects near room temperature. Current-voltage (I-V) measurements show clear periodic oscillations and a dramatic collapse of peak's maximum at various temperatures. Analysis of energy spacing relates the charging energy to a dot of ∼8 nm in size and also suggesting tunneling is via the first excited state. These low-power ∼30 pW and low cost devices can be very useful for the next generation nanoelectronics. View full abstract»

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  • Direct imaging of electron transport within a quantum point contact

    Publication Year: 2005 , Page(s): 754 - 757 vol. 2
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    Much attention has been given to sub-1G0 (=2e2/h) features in the transmission curve of a quantum point contact (e.g.: 0.5G0, 0.7G0). Explanations for this phenomenon have been attributed to many-body interactions such as the Kondo effect or the formation of spin polarized currents. We have used scanning gate microscopy to directly observe the local features of the transport associated with sub-1G0 structures. Images taken with this technique reveal striking features such as weak localization induced within the constriction as well as the formation of self-consistent potentials in the QPC. View full abstract»

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  • The effect of device geometry on the static and dynamic response of carbon nanotube field effect transistors

    Publication Year: 2005 , Page(s): 758 - 761 vol. 2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (291 KB) |  | HTML iconHTML  

    A numerical study of ohmic contact carbon nanotube field effect transistors is presented. The effect of the gate-source and gate-drain spacers on the static and dynamic response of the device was studied. Simulation results suggest that by appropriately selecting the gate-source and gate-drain spacers both the dynamic and static characteristics of the device are improved. View full abstract»

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  • Photonic crystal vertical cavity lasers and arrays

    Publication Year: 2005 , Page(s): 762 - 763 vol. 2
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    Photonic crystal confinement in vertical cavity surface emitting lasers is demonstrated as a technology for achieving operation in the fundamental transverse mode with up to several milliwatts of output power, and is extended to multiple defects to achieve in-phase coherent coupling within a 2-dimensional array. View full abstract»

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  • Two-photon absorption and resonance enhancement of second harmonic in ZnO nanowires

    Publication Year: 2005 , Page(s): 764 - 767 vol. 2
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    ZnO nanowires are prepared using vapor-liquid-solid process. Two-photon absorption measurement has been carried out using femtosecond laser pulses ranging from 700-800 nm. In addition to the deep-level green emission around 530 nm due to the surface defect and the near band-edge ultraviolet emission around 360 nm due to the exciton, a second harmonic peak has been observed. The strength of the frequency-doubled component is enhancing while tuning the two-photon absorption wavelength towards the exciton wavelength of the nanowires, due to resonant exciton absorption. View full abstract»

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  • Si-based light emission at 1530 nm with optical gain using mixture of Er2O3, P2O5, Yb2O3 nanoparticles and spin-on glass

    Publication Year: 2005 , Page(s): 768 - 771 vol. 2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (358 KB) |  | HTML iconHTML  

    We explore a new way of light emission at 1530 nm. The light-emitting layer contains the mixture of Er2O3 nanoparticles and spin-on glass. It is deposited on silicon wafers. This layer is very thin, but exhibits optical gain. We can also improve the emission efficiency by introducing P2O5 and Yb2O3 nanoparticles. View full abstract»

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  • Organic/inorganic optical nanocomposite with highly-doped rare-earth nanoclusters: novel phosphors for white LEDs

    Publication Year: 2005 , Page(s): 772 - 775 vol. 2
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    Organic/inorganic optical nanocomposite with highly-doped rare-earth (RE) nanoclusters has been developed. The nanocluster, having RE-metal (RE-M) complex alkoxide structure (RE|M(OR)4|3), was designed to suppress nonradiative transitions due both to multi-phonon relaxation and concentration quenching while maintaining preferable solubility in organic materials. Based on this concept, europium (Eu3+)-, terbium (Tb3+)-, and cerium (Ce3+)-based nanoclusters (RE|Al(OBu5)4|3) dispersed in propyleneglycol α-monomethyl ether, each of which exhibiting red, green, and blue luminescence, respectively, were synthesized. Photoluminescence spectra suggest that these nanoclusters can be good candidates for RGB-type white LEDs. Further, acrylic-resin-based organic/inorganic nanocomposite was successfully fabricated using Eu3+|Al(OBu5)4|3. View full abstract»

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  • Titania porous network structure for solar cell application

    Publication Year: 2005 , Page(s): 776 - 779 vol. 2
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    The porous titanium dioxide network structure with adjustable average pore size were prepared. The different pore sizes were obtained by controlling the titanium precursor concentration. The porous anatase titania network structure with high surface area is thermally stable and uniform over the whole sample area. The use of these structures in organic solar cells yielded considerable improvements in the short circuit currents compared to previous reports on TiO2/polymer solar cells. View full abstract»

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  • Fabrication and electrical transport properties of nickel monosilicide nanowires

    Publication Year: 2005 , Page(s): 780 - 783 vol. 2
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    Nickel silicide nanowires (NSNWs) have been fabricated and characterized. We propose a fabrication process for one-dimensional silicon nanowires (SiNWs) using scanning probe lithography (SPL) technology and anisotropic wet etching with tetramethylammonium hydroxide (TMAH) solution on a (100) Si layer of silicon on insulator (SOI) substrate. Subsequently, the thin nickel films (∼50 nm) evaporated on SiNWs and the nickel monosilicide was formed by solid-state reaction between nickel and silicon under a rapid thermal annealing (RTA) in N2 ambient for 1 min. Then, the electrical properties of the SiNWs and NSNWs have also been examined and compared. View full abstract»

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  • Effects of dot height uniformity on the performance of 1.3 μm InAs quantum dot lasers

    Publication Year: 2005 , Page(s): 784 - 787 vol. 2
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    We have systematically investigated the growth parameters of InAs quantum dots (QDs) so as to preserve the uniformity of dot height for 1.3 μm QD laser diodes. Devices that are prepared using the optimized growth conditions exhibit threshold current as low as 50 mA, and internal quantum efficiency as high as 63% under continuous-wave operation. View full abstract»

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  • High temperature stable n-i-n resonant tunneling diode embedded InAs quantum dots in GaAs/AlxGa1-xAs double barriers

    Publication Year: 2005 , Page(s): 788 - 791 vol. 2
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    The quantum dot (QD) resonant tunneling diode (RTD) with AlxGa1-xAs double-barriers has been investigated under operating large temperature ranges. A superior temperature-stability of peak-to-valley current ratio (PVR) is demonstrated. The electrons of resonant tunneling transport via nm-scale InAs quantum dots buried in GaAs spacer layers bounded by a pair of very thin Al0.3Ga0.7As barriers. View full abstract»

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  • Optical study of Ge quantum dots and infrared photodetectors

    Publication Year: 2005 , Page(s): 792 - 794 vol. 2
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    Stacked Ge quantum dots were grown on Si(100) by ultra-high vacuum chemical vapor deposition (UHV/CVD). Obvious blueshift (87 meV) observed from PL spectrum under 10 K demonstrates strong quantum confinement in Ge dots. Based on the material, PIiN structure quantum dot infrared photodetectors (QDIPs) were fabricated. At room temperature, I-V measurement showed a low dark current density of 1.7 × 10-6 A/cm2 at -3 V. The maximum photocurrent responsivity of 0.52 A/W at 774 nm was achieved, and 0.043 mA/W at 1.31 μm was found. The dots layers were considered to trap the light in the intrinsic region, and thus increase the absorption. Finally, samples of structural optimization were proposed. View full abstract»

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  • Assembly of nanocrystalline silicon quantum dots based on a colloidal solution method

    Publication Year: 2005 , Page(s): 795 - 798 vol. 2
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    In this paper we propose and develop a new bottom-up approach to the formation of silicon nanostructures based on assembly of nanocrystalline (nc) Si dots from the colloidal solution. The nc-Si dots with a diameter of 8 ± 1 nm were fabricated by using VHF plasma decomposition of pulsed SiH4 gas supply and deposited on the substrate randomly. For preparing the nc-Si dot colloidal solution, we first examined various kinds of solvent. The substrates on which the nc-Si dots deposited were immersed into the solvents, and ultra sonic treatment was applied for a few tens seconds. It was found that methanol works as a suitable solvent for nc-Si dots. The nc-Si dot solution was then condensed by evaporating the solvent a fraction. We dropped the nc-Si dot solution onto other substrates and evaporated it completely. We observed that the nc-Si dots were assembled in the solution via the lateral capillary meniscus force which works as an attractive force between the dots. Use of SiO2 substrate with good surface wettability with the solution was found vital to have the maximum meniscus force and to have two-dimensional assembly of the dots. The evaporation speed was carefully controlled via temperature and evaporation pressure to achieve high dot density assembly. In addition, we examined the assembly of the nc-Si dots on the silicon-on-insulator substrates with various kinds of nanoscale patterning and succeeded in making the nc-Si dots cluster bridging between the nanoelectrodes with a gap of as small as 20 nm. View full abstract»

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  • Contactless electroreflectance study of CdSe/ZnBeSe quantum dots grown by molecular-beam epitaxy

    Publication Year: 2005 , Page(s): 799 - 802 vol. 2
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    Contactless electroreflectance was used to investigate the capped CdSe/ZnBeSe and CdSe/ZnSe quantum-dot (QD) structures grown by molecular beam epitaxy on GaAs [001] substrates. The features originating from the QDs transitions for the CdSe QDs sandwiched by ZnBeSe show blue shifts and narrower lineshape as compared to those grown on ZnSe. The blue shifts of the QD transitions are related to the smaller QD size and the slightly higher barrier energy due to the presence of Be, while the smaller broadening parameters indicate the higher uniformity of the QD size distribution of the ZnBeSe sample. View full abstract»

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  • Enhancement of spontaneous emission from CdSe quantum dots by 3-D silica photonic crystal

    Publication Year: 2005 , Page(s): 803 - 806 vol. 2
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    We have demonstrated that the luminescence properties of CdSe nanoparticles can be manipulated by self-assembled silica photonic crystal. When the emitting wavelength of nanoparticles matches the stop band of photonic crystal, the photoluminescence of the CdSe nanoparticles can be greatly enhanced by up to 5 times, by changing the collection angle of photoluminescence measurements, the photoluminescence intensity of CdSe embedded in photonic crystal can also be controlled. View full abstract»

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  • Building and deploying community nanotechnology software tools on nanoHUB.org - atomistic simulations of multimillion-atom quantum dot nanostructures

    Publication Year: 2005
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    The growth of self-assembled semiconductor quantum dots (QDs) is driven by strain, induced by the mismatch of the lattice constants of the QD material (in this work, InAs) and that of the barrier material (GaAs). The resulting long-range strain field strongly modifies the energy diagram of the system, and has to be accounted for in realistic simulations of QD electronic properties. The nanoelectronic modeling tool NEMO-3D is designed to provide quantitative estimates of QD-bound electron and hole states by treating the system on the atomistic level. In this paper, a systematic study of the strain calculated within a domain consisting of up to 64 million atoms, followed by an electronic calculation on a subdomain containing up to 21 million atoms is presented. Unique and targeted eigenstates can be extracted from system matrices of order 4×10. View full abstract»

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  • Wigner simulation of the transition of a 'single' to 'double' barrier DMS device

    Publication Year: 2005 , Page(s): 808 - 810 vol. 2
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (263 KB) |  | HTML iconHTML  

    The presence of dilute magnetic semiconductors (DMS) enriches the design potential of nano scale barrier devices. Placement of these DMS layers within or adjacent to a barrier can effectively lower or raise the barrier height for carriers of different spin and thereby introduce separate but coupled components of current. The magnetic field in high g-factor devices then can function as a pseudo third terminal. In anticipation of an n-type technology with these materials we examine the development of a barrier device that contains a DMS layer strategically placed so that in the presence of a magnetic field the barrier device is transformed into a double barrier device. The goal of this design is to create a device that will show tunneling resonances. Some early calculations with this structure will be presented showing the possibilities, pitfalls and potential for designing such a structure. View full abstract»

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  • Inelastic tunneling shot noise in quantum dot systems

    Publication Year: 2005 , Page(s): 811 - 814 vol. 2
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    We analyze the role of inelastic electron scattering by phonons on current and its fluctuations in a quantum dot (QD) between two leads nonperturbatively using a recently developed mapping of the many-body electron-phonon coupling problem onto a multichannel single-electron scattering problem. Using the Buttiker scattering theory of noise correlations in a two-terminal mesoscopic conductor, we derive explicit expressions for current and zero-frequency current-current fluctuations in terms of transmission and reflection amplitudes. The derived formulae are used to calculate the shot noise properties of quantum dot systems. View full abstract»

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  • Spin-dependent electron transport along a molecular wire in a metal (probe)-vacuum-molecule-metal system: the effect of the size and the shape of the probe tip

    Publication Year: 2005 , Page(s): 815 - 818 vol. 2
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    We present the results of a first-principles quantum mechanical study of spin-dependent electron transport along a molecular wire investigating the effects of the size and the shape of the probe tip on the tunneling current. A periodic, gradient-corrected density functional method together with Bardeen, Tersoff and Hamann formalism is employed in this study. The electron tunneling through a self-assembled monolayer of benzene 1,4-dithiol on the Ni(111) substrate is found to be strongly dependent on both shape and size of the probe tip. View full abstract»

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  • Molecular electronic latches and memories

    Publication Year: 2005 , Page(s): 819 - 822 vol. 2
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (451 KB) |  | HTML iconHTML  

    Many two terminal molecular devices functioning as diodes have been synthesized with responses similar to solid state devices such as rectifying and resonant tunneling diodes. In this paper, the feasibility of integrating these molecular diodes into current circuit architectures is explored. A bistable latch and memory architecture are simulated using IV data from the 2'-amino-4-ethynylphenyl-4'-ethynylphenyl-5'-nitro-1-bensenethiolate molecule previously published by the Reed group at Yale University. HSPICE simulation results are used to illustrate the performance of a bistable latch and a memory array. View full abstract»

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