23 research outputs found
Electrochemical fabrication of ultralow noise metallic nanowires with hcp crystalline lattice
We experimentally demonstrate that low-frequency electrical noise in silver
nanowires is heavily suppressed when the crystal structure of the nanowires is
hexagonal closed pack (hcp) rather than face centered cubic (fcc). Using a
low-potential electrochemical method we have grown single crystalline silver
nanowires with hcp crystal structure, in which the noise at room temperature is
two to six orders of magnitude lower than that in the conventional fcc
nanowires of the same diameter. We suggest that motion of dislocations is
probably the primary source of electrical noise in metallic nanowires, which is
strongly diminished in hcp crystals.Comment: 7 pages, 4 figure
Influence of the substrate-induced strain and irradiation disorder on the Peierls transition in TTF-TCNQ microdomains
The influence of the combined effects of substrate-induced strain, finite
size and electron irradiation-induced defects have been studied on individual
micron-sized domains of the organic charge transfer compound
tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) by temperature-dependent
conductivity and current-voltage measurements. The individual domains have been
isolated by focused ion beam etching and electrically contacted by focused ion
and electron beam induced deposition of metallic contacts. The
temperature-dependent conductivity follows a variable range hopping behavior
which shows a crossover of the exponent as the Peierls transition is
approached. The low temperature behavior is analyzed within the segmented rod
model of Fogler, Teber and Shklowskii, as originally developed for a
charge-ordered quasi one-dimensional electron crystal. The results are compared
with data obtained on as-grown and electron irradiated epitaxial TTF-TCNQ thin
films of the two-domain type
Observation of Peierls transition in nanowires (diameter similar to 130 nm) of the charge transfer molecule TTF-TCNQ synthesized by electric-field-directed growth
We report the growth of nanowires of the charge transfer complex tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) with diameters as low as 130 nm and show that such nanowires can show Peierls transitions at low temperatures. The wires of sub-micron length were grown between two prefabricated electrodes (with sub-micron gap) by vapor phase growth from a single source by applying an electric field between the electrodes during the growth process. The nanowires so grown show a charge transfer ratio similar to 0.57, which is close to that seen in bulk crystals. Below the transition the transport is strongly nonlinear and can be interpreted as originating from de-pinning of CDW that forms at the Peierls transition
Electric Field Directed Growth of Molecular Wires of Charge Transfer Molecules on Prefabricated Metal Electrodes
Molecular wires of charge transfer molecules were formed by co-evaporating the 7 7 8 8-Tetracyanoquinodimethane [TCNQ] (acceptor) and Tetrathiafulvalene [TTF] (donor) molecules across prefabricated metal electrodes. Molecular wires of TTF TCNQ were also formed by evaporating single complex of TTF:TCNQ across prefabricated metal electrodes The prefabricated metal electrodes were made using electron beam lithography on SiO2 and glass cover slip substrates. Even though TTF: TCNQ wires grown from both co-evaporation and evaporation techniques show semiconductor like behavior in temperature dependence of resistance they show different activation energies due the difference in stoichiometry of TTF and TCNQ
Adhesion behaviour of self-assembled alkanethiol monolayers on silver at different stages of growth
We studied the development of interfacial energy of alkanethiol self-assembled monolayers on Ag/mica substrates by force-displacement spectroscopy using an atomic force microscope. Self-assembled monolayers of decanethiol and octadecanethiol were studied. The growth of the monolayer as a function of time was studied by an ellipsometer for three different concentrations of decanethiol and octadecanethiol. The thiols led to well-ordered self-assembled monolayer that showed atomic resolution images by lateral force microscopy mode. The behaviour of showed non-monotonic variation in stages of adsorption, which was more prominent for short chain length decanethiol. The reached a limiting value of for decanethiol and for octadecanethiol