5,018 research outputs found
Controlled fabrication of single electron transistors from single-walled carbon nanotubes
Single electron transistors (SETs) are fabricated by placing single walled
carbon nanotubes (SWNTs) on a 100 nm wide local Al/Al2O3 bottom gate and then
contacting with Pd electrodes. Coulomb oscillations up to 125 K were observed
and charging energies of 12-15 meV with level spacing of ~5 meV were measured
from the Couloumb diamond, in agreement with a dot size of ~100 nm, implying
that the local gate defines the dot size by bending SWNT at the edges and
controls its operation. This "mechanical template" approach may facilitate
large scale fabrication of SET devices using SWNT.Comment: 5 pages, 3 figure
Socrates and Protagoras
Stokes provides a close reading of the arguments in Plato\u27s Protagoras, focusing especially on Socrates\u27 questions after Protagoras\u27 Great Speech
High quality solution processed carbon nanotube transistors assembled by dielectrophoresis
We report on high quality individual solution processed single-walled carbon nanotube (SWNT) field effect transistors assembled from a commercial surfactant free solution via dielectrophoresis. The devices show field effect mobilities up to 1380 cm(2)/V s and on-state conductance up to 6 mu S. The mobility values are an order of magnitude improvement over previous solution processed SWNT devices and close to the theoretical limit. These results demonstrate that high quality SWNT devices can be obtained from solution processing and will have significant impact in high yield fabrication of SWNT nanoelectronic devices
Exponentially small heteroclinic breakdown in the generic Hopf-zero singularity
In this paper we prove the breakdown of an heteroclinic connection in the
analytic versal unfoldings of the generic Hopf-Zero singularity in an open set
of the parameter space. This heteroclinic orbit appears at any order if one
performs the normal form around the origin, therefore it is a phenomenon
"beyond all orders". In this paper we provide a formula for the distance
between the corresponding stable and unstable one dimensional manifolds which
is given by an exponentially small function in the perturbation parameter. Our
result applies both for conservative and dissipative unfoldings
Stochastic Stokes' drift of a flexible dumbbell
We consider the stochastic Stokes drift of a flexible dumbbell. The dumbbell
consists of two isotropic Brownian particles connected by a linear spring with
zero natural length, and is advected by a sinusoidal wave. We find an
asymptotic approximation for the Stokes drift in the limit of a weak wave, and
find good agreement with the results of a Monte Carlo simulation. We show that
it is possible to use this effect to sort particles by their flexibility even
when all the particles have the same diffusivity.Comment: 12 pages, 1 figur
Low temperature electron transport spectroscopy of mechanically templated carbon nanotube single electron transistors
We report electronic transport investigations of mechanically templated carbon nanotube single electron transistors (SETs). The devices were fabricated on a Si/SiO2 substrate by controllably placing individual single walled carbon nanotubes (SWNTs) between the source and drain electrodes via dielectrophoresis with a 100 nm wide local Al/Al2O3 bottom gate in the middle. From the low temperature electronic transport measurements, we show that a quantum dot is formed whose charging energy can be tuned from 10 to 90 meV by varying both the local gate and Si backgate. The temperature dependent measurements show that the Coulomb oscillations persist up to 250 K. The transport properties can be explained by a simple potential configuration, which suggests that two tunnel barriers are formed due to the bending of the SWNT at the local gate edges and that the size of the dot and tunnel barrier transparency can be tuned by the gates allowing the operation of SET in a wide temperature range and thereby realizing a controllable and tunable SET. Our simple fabrication technique and its tunability over a large temperature range could facilitate large scale fabrication of SET for practical applications
- …