Formation of silicon tips with <1 nm radius
TL;DR: In this paper, a method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm, formed by oxidation of 5μm-high silicon cones through exploitation of a known oxidation inhibition of silicon at regions of high curvature.
Abstract: Electron emitters in vacuum microelectronic devices need sharp tips in order to permit electron emission at moderate voltages A method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm These tips are formed by oxidation of 5‐μm‐high silicon cones through exploitation of a known oxidation inhibition of silicon at regions of high curvature
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TL;DR: The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation AFM (FM-AFM), as well as other dynamic methods as discussed by the authors.
Abstract: This article reviews the progress of atomic force microscopy in ultrahigh vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows us to image surfaces of conductors and insulators in vacuum with atomic resolution. The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation atomic force microscopy (FM-AFM). This technique, as well as other dynamic methods, is explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened our theoretical understanding of frequency-modulation atomic force microscopy. Consequently spatial resolution and ease of use have been increased dramatically. Vacuum atomic force microscopy opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.
1,948 citations
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...Due to the anisotropic etching rates of Si and SiO2 , these tips can be etched so that they develop a very sharp apex (Marcus et al., 1990), as shown in Fig....
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TL;DR: This work has engineered individual biomolecular motors and nanoscale inorganic systems, and their integration in a hybrid nanomechanical device powered by a biomolescular motor is described.
Abstract: Biomolecular motors such as F 1 –adenosine triphosphate synthase (F 1 -ATPase) and myosin are similar in size, and they generate forces compatible with currently producible nanoengineered structures. We have engineered individual biomolecular motors and nanoscale inorganic systems, and we describe their integration in a hybrid nanomechanical device powered by a biomolecular motor. The device consisted of three components: an engineered substrate, an F 1 -ATPase biomolecular motor, and fabricated nanopropellers. Rotation of the nanopropeller was initiated with 2 mM adenosine triphosphate and inhibited by sodium azide.
612 citations
TL;DR: In this article, a review of field emission cold cathode materials has been presented, focusing on several kinds of novel cold cathodes that have been developed in the past decade, including materials for microfabricated field-emitter arrays, diamond and related films, carbon nanotubes, other quasi one-dimensional nanomaterials and printable composite materials.
Abstract: Field emission (FE) is based on the physical phenomenon of quantum tunneling, in which electrons are injected from the surface of materials into vacuum under the influence of an applied electric field. A variety of field emission cold cathode materials have been developed to date. In this review, we shall focus on several kinds of novel cold cathode materials that have been developed in the past decade. These include materials for microfabricated field-emitter arrays, diamond and related films, carbon nanotubes, other quasi one-dimensional nanomaterials and printable composite materials. In addition, cold cathode materials have a wide range of applications such as in flat panel displays, high-power vacuum electronic devices, microwave-generation devices, vacuum microelectronic devices and vacuum nanoelectronic devices. Applications are in consumer goods, military industries and also space technology. A comprehensive overview of the various applications is presented. Recently, recognizing the strong possibility that vacuum nanoelectronic devices using quasi one-dimensional nanomaterials, such as carbon nanotubes may emit electrons with driving voltages comparable to that of a solid-state device, there is a growing interest in novel applications of such devices. With such exciting opportunities, there is now a flurry of activities to explore applications far beyond those considered for the conventional hot cathodes that operate on thermionic emission. We shall discuss the details of a number of fascinating potential applications.
539 citations
01 Jul 1994
TL;DR: The history, physics, and current status of vacuum microelectronic devices can be found in this paper, where a review of a wide variety of demonstrated and proposed devices based on vacuum micro-electronic principles, including electron guns, microwave tubes, and flat-panel displays are discussed.
Abstract: In this review/tutorial paper, we cover the history, physics, and current status of vacuum microelectronic devices. First we overview the performance requirements of vacuum microelectronic devices necessary for them to replace, or fill voids left by, solid state devices. Next we discuss the physical characteristics of micro-field-emission sources important to device applications. These characteristics include fundamental features, such as current-voltage data and noise, in addition to engineering considerations, such as life expectancy and procedures for tube assembly. We conclude with a review of a wide variety of demonstrated and proposed devices based on vacuum microelectronic principles, including electron guns, microwave tubes, and flat-panel displays. >
269 citations
TL;DR: A simple method of substrate preparation for imaging circular DNA molecules with the scanning force microscope (SFM) on mica that has been soaked in magnesium acetate, sonicated and glow-discharged is presented.
252 citations
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TL;DR: In this paper, the authors proposed a simplified mathematical formulation made possible by the symmetry in cylindrical structures, and compared with experimental data, possible applications, and limitations of the model are also discussed.
Abstract: For pt.I see ibid., vol.ED-34, p.1008-17 (May 1987). The authors propose that the stress from two-dimensional oxide deformation affects the kinetic parameter in the Deal-Grove model (1965). In particular, the viscous stress associated with the nonuniform deformation of the oxide is identified as the fundamental force of retardation. In this model, the stress normal to the Si-SiO/sub 2/ interface reduces the surface reaction rate in both convex and concave surfaces, whereas the stress in the bulk of the oxide (compressive for concave and tensile for convex surfaces) is responsible for the thinner oxides on the concave structures. The model is described by a simplified mathematical formulation made possible by the symmetry in cylindrical structures. Comparisons with experimental data, possible applications, and limitations of the model are also discussed. >
423 citations
TL;DR: In this article, the authors introduced a unique experimental approach in which extensive data were obtained concerning the oxidation of cylindrical silicon structures of controlled radii of curvature, and quantitatively demonstrated that the oxidization of curved silicon surfaces is retarded at low temperatures and sharp curvatures, and the retardation is more severe on concave than convex structures.
Abstract: With continued miniaturization and the development of new devices, the highly nonuniform oxidation of two-dimensional non-planar silicon structures is playing an increasingly important role. An understanding of this subject has been limited by insufficient experimental data and difficulties in two-dimensional numerical simulation. This paper introduces a unique experimental approach in which extensive data were obtained concerning the oxidation of cylindrical silicon structures of controlled radii of curvature. It is quantitatively demonstrated that the oxidation of curved silicon surfaces is retarded at low temperatures and sharp curvatures, and that the retardation is more severe on concave than convex structures. These observations will be interpreted using a physical model based on stress effects on oxide growth parameters. The theoretical analysis and modeling will be reported in detail in a separate paper [1].
260 citations
TL;DR: In this article, a 30% decrease in oxide thickness at silicon step edges following 900° and 950°C wet oxidation is attributed to the effect of locally compressive intrinsic stress within the oxide on the solubility of oxygen.
Abstract: Nonplanar silicon surfaces were prepared and oxidized at 900°–1100°C and the oxide morphology was studied by transmission electron microscopy of thin sections. A 30% decrease in oxide thickness at silicon step edges following 900° and 950°C wet oxidation is attributed to the effect of locally compressive intrinsic stress within the oxide on the solubility of oxygen. Oxidation inhibition becomes less at higher temperatures due to the relief of stress (during growth) by viscous flow of the oxide.
260 citations
TL;DR: In this paper, the curvature radius at the convex corner of a trenched Si surface and electric field intensification was modeled as a rounding-off oxidation, and a simple one-dimensional model that considered both stress generation during Si oxidation and stress relaxation by oxide viscous flow was proposed.
Abstract: We report that, based on the curvature radius at the convex corner of a trenched Si surface and electric field intensification, sacrificial thermal oxidation before gate oxide formation is very effective to round off the convex corner. We call it a rounding-off oxidation. From a simple one-dimensional model that considers both stress generation during Si oxidation and Stress relaxation by oxide viscous flow, it is foreseen that oxidation in a diluted oxidizing ambient and/or at a higher oxidation temperature reduces the stress in the oxide films. Experimentally, we report that the rounding-off oxidation with the above condition effectively rounds off the convex Si corner and decreases the thin gate oxide leakage currents and that the addition of a few percent of H 2 O to the dry oxygen rounding,off oxidation ambient is also effective. The relation between the sacrificial rounding-off oxidation and the time-dependent dielectric breakdown of thin gate oxides formed at the convex corner is also shown.
73 citations
TL;DR: In this paper, the emission properties of arrays of field emission cathodes, fabricated using thin film technology and micro-lithography, were reviewed and it was argued that from the standpoint of life, stability, energy distribution, current fluctuation noise, and average current density over the array, these cathodes have demonstrated sufficient promise to justify their trial use in a range of electronic devices.
50 citations