5,513 research outputs found

    Nonphotolithographic nanoscale memory density prospects

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    Technologies are now emerging to construct molecular-scale electronic wires and switches using bottom-up self-assembly. This opens the possibility of constructing nanoscale circuits and memories where active devices are just a few nanometers square and wire pitches may be on the order of ten nanometers. The features can be defined at this scale without using photolithography. The available assembly techniques have relatively high defect rates compared to conventional lithographic integrated circuits and can only produce very regular structures. Nonetheless, with proper memory organization, it is reasonable to expect these technologies to provide memory densities in excess of 10/sup 11/ b/cm/sup 2/ with modest active power requirements under 0.6 W/Tb/s for random read operations

    Integrated chaos generators

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    This paper surveys the different design issues, from mathematical model to silicon, involved on the design of integrated circuits for the generation of chaotic behavior.Comisión Interministerial de Ciencia y Tecnología 1FD97-1611(TIC)European Commission ESPRIT 3110

    Array-based architecture for FET-based, nanoscale electronics

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    Advances in our basic scientific understanding at the molecular and atomic level place us on the verge of engineering designer structures with key features at the single nanometer scale. This offers us the opportunity to design computing systems at what may be the ultimate limits on device size. At this scale, we are faced with new challenges and a new cost structure which motivates different computing architectures than we found efficient and appropriate in conventional very large scale integration (VLSI). We sketch a basic architecture for nanoscale electronics based on carbon nanotubes, silicon nanowires, and nano-scale FETs. This architecture can provide universal logic functionality with all logic and signal restoration operating at the nanoscale. The key properties of this architecture are its minimalism, defect tolerance, and compatibility with emerging bottom-up nanoscale fabrication techniques. The architecture further supports micro-to-nanoscale interfacing for communication with conventional integrated circuits and bootstrap loading

    Designing with Iontronic Logic Gates -- From a Single Polyelectrolyte Diode to Small Scale Integration

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    This article presents the implementation of on-chip iontronic circuits via small-scale integration of multiple ionic logic gates made of bi-polar polyelectrolyte diodes. These ionic circuits are analogous to solid-state electronic circuits, with ions as the charge carriers instead of electrons/holes. We experimentally characterize the responses of a single fluidic diode made of a junction of oppositely charged polyelectrolytes (i.e., anion and cation exchange membranes), with a similar underlying mechanism as a solid-state p- and n-type junction. This served to carry out pre-designed logical computations in various architectures by integrating multiple diode-based logic gates, where the electrical signal between the integrated gates was transmitted entirely through ions. The findings shed light on the limitations affecting the number of logic gates that can be integrated, the degradation of the electrical signal, their transient response, and the design rules that can improve the performance of iontronic circuits

    Thermomass Theory: A Mechanical Pathway to Analyze Anomalous Heat Conduction in Nanomaterials

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    The synthesis and measurements of nanomaterials have yielded significant advances in the past decades. In the area of thermal conduction, the nanomaterials exhibit anomalous behavior such as size-dependent thermal conductivity, thermal rectification, and ultra-high thermoelectric properties. The theoretical understanding and modeling on these behaviors are much desired. In this chapter, we study the thermal conduction in nanomaterials through the thermomass theory, which models the heat transfer from a fluid mechanics viewpoint. The control equations of the equivalent mass of the thermal energy are formulated following the continuum mechanics principles, which give the general heat conduction law. It incorporates nonlinear effects such as spatial acceleration and boundary resistance, which can overcome the drawbacks of the traditional Fourier’s law in nanoscale systems. By the thermomass theory, we successfully model the size-dependent effective thermal conductivity in nanosystems. Furthermore, the thermal rectification as well as the thermoelectric enhancement in nanosystems is also discussed with the present framework

    Deterministic Addressing of Nanoscale Devices Assembled at Sublithographic Pitches

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    Multiple techniques have now been proposed using random addressing to build demultiplexers which interface between the large pitch of lithographically patterned features and the smaller pitch of self-assembled sublithographic nanowires. At the same time, the relatively high defect rates expected for molecular-sized devices and wires dictate that we design architectures with spare components so we can map around defective elements. To accommodate and mask both of these effects, we introduce a programmable addressing scheme which can be used to provide deterministic addresses for decoders built with random nanoscale addressing and potentially defective wires. We describe how this programmable addressing scheme can be implemented with emerging, nanoscale building blocks and show how to build deterministically addressable memory banks. We characterize the area required for this programmable addressing scheme. For 2048 x 2048 memory banks, the area overhead for address correction is less than 33%, delivering net memory densities around 10^11 b/cm^2

    Molecular Electronics

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    Molecular electronics describes the field in which molecules are utilized as the active (switching, sensing, etc.) or passive (current rectifiers, surface passivants) elements in electronic devices. This review focuses on experimental aspects of molecular electronics that researchers have elucidated over the past decade or so and that relate to the fabrication of molecular electronic devices in which the molecular components are readily distinguished within the electronic properties of the device. Materials, fabrication methods, and methods for characterizing electrode materials, molecular monolayers, and molecule/electrode interfaces are discussed. A particular focus is on devices in which the molecules or molecular monolayer are sandwiched between two immobile electrodes. Four specific examples of such devices, in which the electron transport characteristics reflect distinctly molecular properties, are discussed

    Three-way electrical gating characteristics of metallic Y-junction carbon nanotubes

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    Y-junction based carbon nanotube (CNT) transistors exhibit interesting switching behaviors, and have the structural advantage that the electrical gate for current modulation can be formed by any of the three constituent branches. In this letter, we report on the gating characteristics of metallic Y-CNT morphologies. By measuring the output conductance and transconductance we conclude that the efficiency and gain depend on the branch diameter and is electric field controlled. Based on these principles, we propose a design for a Y-junction based CNT switching device, with tunable electrical properties
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