19,426 research outputs found
Controlling ion transport through nanopores: modeling transistor behavior
We present a modeling study of a nanopore-based transistor computed by a
mean-field continuum theory (Poisson-Nernst-Planck, PNP) and a hybrid method
including particle simulation (Local Equilibrium Monte Carlo, LEMC) that is
able to take ionic correlations into account including finite size of ions. The
model is composed of three regions along the pore axis with the left and right
regions determining the ionic species that is the main charge carrier, and the
central region tuning the concentration of that species and, thus, the current
flowing through the nanopore. We consider a model of small dimensions with the
pore radius comparable to the Debye-screening length
(), which, together with large
surface charges provides a mechanism for creating depletion zones and, thus,
controlling ionic current through the device. We report scaling behavior of the
device as a function the parameter.
Qualitative agreement between PNP and LEMC results indicates that mean-field
electrostatic effects determine device behavior to the first order
Nonlinear thermoelectric response due to energy-dependent transport properties of a quantum dot
Quantum dots are useful model systems for studying quantum thermoelectric
behavior because of their highly energy-dependent electron transport
properties, which are tunable by electrostatic gating. As a result of this
strong energy dependence, the thermoelectric response of quantum dots is
expected to be nonlinear with respect to an applied thermal bias. However,
until now this effect has been challenging to observe because, first, it is
experimentally difficult to apply a sufficiently large thermal bias at the
nanoscale and, second, it is difficult to distinguish thermal bias effects from
purely temperature-dependent effects due to overall heating of a device. Here
we take advantage of a novel thermal biasing technique and demonstrate a
nonlinear thermoelectric response in a quantum dot which is defined in a
heterostructured semiconductor nanowire. We also show that a theoretical model
based on the Master equations fully explains the observed nonlinear
thermoelectric response given the energy-dependent transport properties of the
quantum dot.Comment: Cite as: A. Svilans, et al., Physica E (2015),
http://dx.doi.org/10.1016/j.physe.2015.10.00
Gate defined quantum dot realized in a single crystalline InSb nanosheet
Single crystalline InSb nanosheet is an emerging planar semiconductor
material with potential applications in electronics, infrared optoelectronics,
spintronics and topological quantum computing. Here we report on realization of
a quantum dot device from a single crystalline InSb nanosheet grown by
molecular-beam epitaxy. The device is fabricated from the nanosheet on a
Si/SiO2 substrate and the quantum dot confinement is achieved by top gate
technique. Transport measurements show a series of Coulomb diamonds,
demonstrating that the quantum dot is well defined and highly tunable. Tunable,
gate-defined, planar InSb quantum dots offer a renewed platform for developing
semiconductor-based quantum computation technology.Comment: 12 pages, 4 figure
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