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Vacuum Nanoelectronics Conference, 2005. IVNC 2005. Technical Digest of the 18th International

Date 10-14 July 2005

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Displaying Results 1 - 25 of 194
  • Technical Digest of the 18th International Vacuum Nanoelectronics Conference (IEEE Cat. No. 05TH8837)

    Publication Year: 2005
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  • Technical Digest of the 18th International Vacuum Nanoelectronics Conference [Editors]

    Publication Year: 2005 , Page(s): i
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  • Copyright page

    Publication Year: 2005 , Page(s): ii
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  • Conference committee

    Publication Year: 2005 , Page(s): iii - iv
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  • Foreword

    Publication Year: 2005 , Page(s): v
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  • Contents

    Publication Year: 2005 , Page(s): vii - xix
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  • A look at the basic physics of cold field electron emission

    Publication Year: 2005 , Page(s): 1 - 2
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    The paper presents a treatment of basic cold field electron emission (CFE) theory which concentrates mainly on CFE from metals. Fowler-Nordheim (FN) type equations are derived and their limitations are discussed. FN type equations may help with the interpretation of experimental CFE phenomena. Barriers and FN plots are also discussed. View full abstract»

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  • Field-enhanced photoemission from metals and coated materials

    Publication Year: 2005 , Page(s): 3 - 4
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    Photocathode performance is modelled to account for issues that affect electron transport. Theoretical models of field, thermal, and surface effects on photoemission from sub-monolayer low work function coated surfaces as a function of laser parameters, temperature, and applied field are discussed. A time-dependent model of laser heating, thermal propagation, and photoemission and the relative importance of field, thermal, and photoemission contribution are presented. View full abstract»

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  • Simulations of field emission and dielectrophoresis using a monopole-dipole representation of carbon nanotubes

    Publication Year: 2005 , Page(s): 5 - 6
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    A model is presented to compute the polarization of carbon nanotubes, where each atom is described by both a net electric charge and a dipole. The model parameters are adjusted to reproduce the polarizability of C60, C70 as well as the transverse polarizability of (5,5), (6,6) and (9,0) nanotubes. The model gives a better account of the metallicity of these nanotubes that is essential for the modeling of field emission. An extension of the model is also presented, where discrete representation of carbon nanotube is combined with a dielectric-function representation of its environment. This technique provides a complete picture of the potential energy of systems made of carbon nanotubes and metallic elements, which can be applied to field-emission device. View full abstract»

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  • Properties of a field emitter of nanometric radius deduced from curvature of F-N plot

    Publication Year: 2005 , Page(s): 7 - 8
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    The slope of Fowler-Nordheim (F-N) plot is not constant but increases slightly in magnitude as the anode-cathode voltage Va is reduced. Theory for emission from a spherical surface shows that this curvature of slope increases with the curvature of the emitting surface. Through detailed calculation using the change of F-N slope, the radius of curvature of the emitting region, surface field, effective solid angle of emission and electron supply factor can be deduced. View full abstract»

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  • Field electron emission of nanorods of semiconductors of wide energy band gaps

    Publication Year: 2005 , Page(s): 9 - 10
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    It is shown that significant field emission from nanorods of wide band gap semiconductors is possible. The nanorod is assumed to have a thin surface layer containing a large number of localized states originating from defects. Taking SiC as an example, the electrostatic potential, charge distribution, conduction current, tunnelling current, and field enhancement are calculated. It is found that the field-induced insulator to semimetal transition is responsible for the efficient field emission from the nanorods and that field enhancement is not constant with applied fields but varies with the field and has a maximum. View full abstract»

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  • Observation of new quantum interference effect in solids

    Publication Year: 2005 , Page(s): 11 - 12
    Cited by:  Patents (1)
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    The experiments and theoretical basis for reducing the work function of Au and SiO2 thin films are discussed. In order to achieve the quantum interference of free electrons, the geometry of the solid is modified so that the de Broglie waves interfere destructively inside the solid. If a metal surface is modified with patterned indents, the Fermi energy increases and consequently the electron work function decreases. This effect is named the Avto effect. Work function reductions of 0.5 eV and 0.2 eV are observed in Au and SiO2 films, respectively. Comparative measurements of work function are made using the Kelvin probe method based on the compensation of internal contact potential difference. Electron emission from the same thin films are also studied using photoelectron emission microscopy. View full abstract»

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  • Cold cathodes using carbon nanotubes and nanopearls: fabrication and emission characteristics

    Publication Year: 2005 , Page(s): 13 - 14
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    The synthesis and field emission properties of two forms of carbon, the individual vertically aligned nanotubes and nanopearls, are presented. Carbon possesses several properties which make carbon nanotubes and nanopearls extraordinary materials for field emission. They exhibit high electrical conductivity at room temperature and can be very stable emitters even at high temperature. The huge success of carbon nanocompounds as field emitters comes from its fabrication by chemical vapour deposition technology that is not only cost-productive but can also be easily extended to mass production. View full abstract»

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  • Negative resistance region in double-gated silicon field emission arrays

    Publication Year: 2005 , Page(s): 15 - 16
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    Double-gated silicon field emission arrays (FEAs) are fabricated with the tip 400 nm below the extraction gate and 600 nm below the focus. The diameters of the gate and focus apertures are 0.4 μm and 0.7 μm respectively. For this structure, an abrupt drop in anode current is observed when the focus voltage Vf is less than 12 V. For the range of focus voltages 4 V < Vf < 12 V, the anode current initially increases with the gate voltage because the net repulsive force is still small. The emitted current increases with VG due to repulsion by the focus. Eventually, the anode current peaks and a negative resistance region ensue. Further increase of VG shuts off the anode current. For focus voltage > 12 V, the balance between the emission and repulsive forces is such that there is a monotonic increase in anode current with VG and shows no negative resistance region. View full abstract»

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  • Atomic level surface studies of nanotube field emission cathodes

    Publication Year: 2005
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    Carbon nanotubes are of interest due to their unusual chemical and electrical characteristics and have been suggested for use in a wide variety of applications including field emission cathodes. Their small diameter and conductive and semiconductive properties may make them potentially useful field electron emitters. However, there are indications that they, like most field emitters, are sensitive to the vacuum environment in which they operate. In order to understand this sensitivity their emission characteristics should be correlated with the physical morphology and chemical composition of the emitting surface. To this end, we are using the imaging atom probe to correlate the emission characteristics of individual multi-walled nanotubes with their atomic level surface chemical composition and morphology. The initial results of these studies will be presented. View full abstract»

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  • Emission mechanism for field assisted electron emission from a novel multilayered nanocarbon based electron emitter

    Publication Year: 2005 , Page(s): 18 - 19
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    In an effort to develop a relatively low cost-low temperature process based technology compatible with semiconductor technology, a low field electron emission from a nanocarbon based multilayered electron emitter was studied. Some of the results are presented in this paper as well as a possible mechanism of emission from such multilayered electron emitter. View full abstract»

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  • Field emitter arrays for high-current, high-current density, and high frequency operation

    Publication Year: 2005 , Page(s): 20 - 21
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    Common issues of interest when considering a cathode for microwave tube applications are total current, current density, emittance, and parasitic capacitance if beam pre-bunching is planned. Single SRI Spindt-type emitter tips have been shown to be capable of producing over 1 mA of emission when properly processed. However, when working with large arrays of tips, achieving an average emission per tip greater than about 10 muA/tip has been elusive due primarily to insufficient uniformity from tip to tip in the as-fabricated arrays. Recent work in addressing this issue has shown that it is possible to improve tip-to-tip emission uniformity with a pulse-conditioning technique currently under development. Using recently developed lithography techniques, emitter arrays are now fabricated with gate aperture diameters of 0.35 mum and a 1-mum aperture or tip pitch (1-mum space between apertures and tips, or 108 tips/cm2). This configuration would have approximately 785,000 tips in a 1-mm-diameter area, and an average tip loading of less than 1.5 muA/tip would produce 1 amp of total peak emission with a current density of about 130 A/cm2, exceeding most vacuum tube requirements View full abstract»

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  • Smith-Purcell radiation from ultraviolet to infrared using a Si-field emitter

    Publication Year: 2005
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    Smith-Purcell radiation using a Si-field emitter has been generated and detected in both ultraviolet and infrared regions. We passed a 200 nA beam current accelerated in 25-30 kV over a 550 nm pitch grating and detected the 1st harmonic waves of SPR in the infrared region from 1300 to 1400 nm by using an InGaAs detector. In addition to them, the 4th harmonic waves of SPR in the ultraviolet region from 320 to 360 nm were clearly observed by using a CCD detector. These spectra also coincided with those of the calculation using the SPR theory and blue-shifted with increasing the acceleration voltage. As results, we have successfully observed SPR from ultraviolet to infrared using a Si field emitter for the first time. View full abstract»

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  • Milliamp-class field emission devices based on free-standing, two-dimensional carbon nanostructures

    Publication Year: 2005 , Page(s): 24 - 25
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    Recent results using carbon nanosheets (CNS) as the field emission source in a backgated device for high current applications are presented. The device inherently eliminates arcing between the gate and the cathode and also creates a much more open cathode configuration for better vacuum conductance and getter pumping. The device allows for emission site burn out and turn-on of secondary sites. Modelling results also suggest that devices with line widths <3 μm and properly placed nanostructures should be capable of >10 mA/mm2. Devices with 3 μm wide lines have been fabricated and are currently being tested. The maximum current and modulation results from these devices will also be presented. View full abstract»

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  • RF modulation of a 3 mA beam current from a carbon nanotube cathode

    Publication Year: 2005 , Page(s): 26 - 28
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    A micro-triode operating at 30 GHz is currently under development. This triode is composed of two 30 GHz re-entrant resonant cavities (input and output, respectively cathode-grid space and anode-grid space) separated by a grounded thin metallic grid. A dc bias between cathode-grid and anode-grid provides a continuous electron beam. The superposition of a 30 GHz electric field created in the input cavity, leads to increase the average grid current, which is indicative of the electron beam modulation. View full abstract»

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  • An RF-MEMS device with a lateral field-emission detector

    Publication Year: 2005 , Page(s): 29 - 30
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    We propose a new device that utilizes the field-emission effect as a signal-detecting mechanism for RF-MEMS (radio-frequency micro electro mechanical systems) applications. The device consists of a micro electromechanical resonator of BPF (band-pass filter) characteristics and a pair of silicon tips for field-emission, both of which are monolithically integrated by the silicon micromachining technology. The present paper will show a complete set of experimental results on the field-emission current that was controlled by the micromechanical structure, including the latest report on improved fabrication processes for sharper emission tips. View full abstract»

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  • One-dimensional field emission cold-cathode materials and their applications

    Publication Year: 2005 , Page(s): 31 - 32
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    This paper investigates the field emission phenomenon of various nanowires and nanorods. The materials of particular interest include Mo and W and their oxides, SiC and ZnO. Different novel techniques are developed for large-area nanowire synthesis like thermal evaporation, thermal heating and by solid-gas interaction at room temperature View full abstract»

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  • Patchwork field emission properties of lanthanum sulfide thin films

    Publication Year: 2005 , Page(s): 33 - 34
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    The field emission (FE) properties of lanthanum monosulfide (LaS) films, deposited on Si and InP substrates by pulsed laser deposition, have been thoroughly analyzed via the scanning anode field emission microscopy technique (SAFEM, Fig. 1) at different surface locations and at different temperatures. For one location, the full set of measured I-V characteristics (total measured current versus applied voltage) for different values of Z, the distance between the cathode surface and the probe ball, were then analyzed in order to extract the current density J versus actual applied field F (J-F data), within the approximation that the LaS surface is a plane. A characteristic J-F variation is shown in Fig. 2. The work function of the LaS thin film has been extracted from the slope of the plot ln(J/F2) vs 1/F, by using the conventional Fowler-Nordheim relation, leading to a value of ∼0.65 eV which is in agreement with the onset of the electric field needed to observe an emission current density of 1 mA/cm2 at an applied electric field across the vacuum gap around 230 V/μm. View full abstract»

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  • Design and fabrication of single-chip carbon nanotubes vacuum field emission differential amplifier

    Publication Year: 2005 , Page(s): 35 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB) |  | HTML iconHTML  

    In this paper, the design and fabrication of a single chip carbon nanotubes (CNT) vacuum field emission differential amplifier (VFE diff-amp) is presented for the first time. A dual-mask microfabrication process is employed to achieve the single-chip VFE diff-amp that integrates two identical vacuum field emission transistors with built-in split gates and integrated anodes. View full abstract»

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  • New insights in to the mechanisms of fullerene and nanotube formation

    Publication Year: 2005
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    In 1985 buckminsterfullerene (the third allotropic form of carbon) was discovered during experiments designed to unravel the chemistry in red giant carbon stars. The molecule has now come down to Earth giving rise to the fullerenes, a family of pure carbon cage molecules with fascinating properties which promise exciting new developments in 21st century materials science and technology. Fullerene molecules and their elongated nanotube (buckytube) cousins are now the subject of intense study as they promise to play major roles in almost every possible area of future technology from medicine and molecular electronics to civil engineering. However the mechanisms whereby various types of nanostructures assemble are still very poorly understood. Over the last decade or so, we have examined a wide range of methods for nanotube formation and from these studies some interesting new insights have been gained - especially with regard to metal catalysed nanostructure formation. View full abstract»

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