65 research outputs found

    Incoherent dynamics of vibrating single-molecule transistors

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    We study the tunneling conductance of nano-scale quantum ``shuttles'' in connection with a recent experiment (H. Park et al., Nature, 407, 57 (2000)) in which a vibrating C^60 molecule was apparently functioning as the island of a single electron transistor (SET). While our calculation starts from the same model of previous work (D. Boese and H. Schoeller, Europhys. Lett. 54, 66(2001)) we obtain quantitatively different dynamics. Calculated I-V curves exhibit most features present in experimental data with a physically reasonable parameter set, and point to a strong dependence of the oscillator's potential on the electrostatics of the island region. We propose that in a regime where the electric field due to the bias voltage itself affects island position, a "catastrophic" negative differential conductance (NDC) may be realized. This effect is directly attributable to the magnitude of overlap of final and initial quantum oscillator states, and as such represents experimental control over quantum transitions of the oscillator via the macroscopically controllable bias voltage.Comment: 6 pages, LaTex, 6 figure

    Photocurrent Response of Bipyridine Containing Poly( p

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    Nanorings and rods interconnected by self-assembly mimicking an artificial network of neurons

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    [EN] Molecular electronics based on structures ordered as neural networks emerges as the next evolutionary milestone in the construction of nanodevices with unprecedented applications. However, the straightforward formation of geometrically defined and interconnected nanostructures is crucial for the production of electronic circuitry nanoequivalents. Here we report on the molecularly fine-tuned self-assembly of tetrakis-Schiff base compounds into nanosized rings interconnected by unusually large nanorods providing a set of connections that mimic a biological network of neurons. The networks are produced through self-assembly resulting from the molecular conformation and noncovalent intermolecular interactions. These features can be easily generated on flat surfaces and in a polymeric matrix by casting from solution under ambient conditions. The structures can be used to guide the position of electron-transporting agents such as carbon nanotubes on a surface or in a polymer matrix to create electrically conducting networks that can find direct use in constructing nanoelectronic circuits.The research leading to these results has received funding from ICIQ, ICREA, the Spanish Ministerio de Economia y Competitividad (MINECO) through project CTQ2011-27385 and the European Community Seventh Framework Program (FP7-PEOPLE-ITN-2008, CONTACT consortium) under grant agreement number 238363. We acknowledge E. C. Escudero-Adan, M. Martinez-Belmonte and E. Martin from the X-ray department of ICIQ for crystallographic analysis, and M. Moncusi, N. Argany, R. Marimon, M. Stefanova and L. Vojkuvka from the Servei de Recursos Cientifics i Tecnics from Universitat Rovira i Virgili (Tarragona, Spain).Escarcega-Bobadilla, MV.; Zelada-Guillen, GA.; Pyrlin, SV.; Wegrzyn, M.; Ramos, MMD.; Giménez Torres, E.; Stewart, A.... (2013). 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    Selfassembly of nanoelectronic components and circuits using biological templates

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    A multistep self-assembly process is proposed for the preparation of nanometer-scale electronics. The process is based on the assembly of a DNA network that serves, in turn, as a template for the subsequent assembly of functional elements using different levels of molecular recognition ability. Inter-element connectivity and connection to the "macroscopic world" is achieved by instilling electrical functionality to the DNA network. The feasibility of this approach was demonstrated by the DNA-templated self-assembly of a 12 lm long, ca. 1 000 Ã… wide, conductive silver wire connecting two macroscopic electrodes. Since the early days of microelectronics, a major effort has been devoted to the miniaturization of components and circuitry. As a result, the minimal feature size on a commercial chip has decreased gradually from about 10 lm in the early 1970s to ca. 0.18 lm at present. A comprehensive study by the American Semiconductor Industry Association (SIA) predicts a further gradual decrease in feature size to about 0.07 lm in 2 010 [1] Nevertheless, even at these dimensions, the size of components on a chip will still be much larger than the size of the basic data storage component in biological systems such as in the DNA code, about 100 atoms with a volume of ca. 1 000 Ã… 3 . The expected exhaustion of conventional microelectronics has focused considerable scientific and technological interest on two fundamental issues regarding future miniaturized nanoscale electronics: a) Operating principles of alternative, small size, electronic devices In the last two decades, numerous suggestions have been made regarding the nature of the basic operating principles and components of nanometer-scale logic devices, ranging from all-optical and molecular-optical switch systems [4] to transistor-like switching devices based on charging effects (Coulomb blockade). Such single-electron charging effects were found in small grains The expected failure of conventional physical processes at molecular scales presents the challenge of providing alternative schemes for the construction of useful electronic devices from nanometer-size and molecular building blocks. The major obstacles originate from the lack of appropriate tools for individual handling and manipulation of such small species, namely: a) positioning of molecularscale components at molecularly accurate addresses, b) inducing inter-component wiring for establishing welldefined, functional electrical connectivity, c) establishing an effective interface between molecular-scale circuitry and the macroscopic world. Due to obvious limitations in physically manipulating molecular size objects, it is widely accepted that electronic circuitry that is composed of nanometer-or molecular-size objects should be assembled from its building blocks using molecular recognition and self-assembly processes A major obstacle in implementing self-assembly processes for the construction of electrically functional elements lies in the fact that molecular recognition ability and electrical properties belong to two, probably mutually exclusive, classes of materials. On one hand, one can find metals and semiconductors as part of the inorganic world. Such materials display the desired electrical properties but possess only trivial molecular recognition ability, capable of forming only a few, rather trivial, lattices. On the other hand, organic-based materials exhibit poor electric properties; most of them are simply insulators. However, som
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