1,797 research outputs found
Silicene Nanomesh
Similar to graphene, zero band gap limits the application of silicene in
nanoelectronics despite of its high carrier mobility. By using first-principles
calculations, we reveal that a band gap is opened in silicene nanomesh (SNM)
when the width W of the wall between the neighboring holes is even. The size of
the band gap increases with the reduced W and has a simple relation with the
ratio of the removed Si atom and the total Si atom numbers of silicene. Quantum
transport simulation reveals that the sub-10 nm single-gated SNM field effect
transistors show excellent performance at zero temperature but such a
performance is greatly degraded at room temperature
Spin transfer nano-oscillators
The use of spin transfer nano-oscillators (STNOs) to generate microwave
signal in nanoscale devices have aroused tremendous and continuous research
interest in recent years. Their key features are frequency tunability,
nanoscale size, broad working temperature, and easy integration with standard
silicon technology. In this feature article, we give an overview of recent
developments and breakthroughs in the materials, geometry design and properties
of STNOs. We focus in more depth on our latest advances in STNOs with
perpendicular anisotropy showing a way to improve the output power of STNO
towards the {\mu}W range. Challenges and perspectives of the STNOs that might
be productive topics for future research were also briefly discussed.Comment: 11 pages, 10 figures, nanoscale 201
Highly Quantum-Confined InAs Nanoscale Membranes
Nanoscale size-effects drastically alter the fundamental properties of
semiconductors. Here, we investigate the dominant role of quantum confinement
in the field-effect device properties of free-standing InAs nanomembranes with
varied thicknesses of 5-50 nm. First, optical absorption studies are performed
by transferring InAs "quantum membranes" (QMs) onto transparent substrates,
from which the quantized sub-bands are directly visualized. These sub-bands
determine the contact resistance of the system with the experimental values
consistent with the expected number of quantum transport modes available for a
given thickness. Finally, the effective electron mobility of InAs QMs is shown
to exhibit anomalous field- and thickness-dependences that are in distinct
contrast to the conventional MOSFET models, arising from the strong quantum
confinement of carriers. The results provide an important advance towards
establishing the fundamental device physics of 2-D semiconductors
Domain wall conduction in multiaxial ferroelectrics
The conductance of domain wall structures consisting of either stripes or
cylindrical domains in multi-axial ferroelectric-semiconductors is analyzed.
The effects of the domain size, wall tilt and curvature, on charge
accumulation, are analyzed using the Landau-Ginsburg Devonshire (LGD) theory
for polarization combined with Poisson equation for charge distributions. Both
the classical ferroelectric parameters including expansion coefficients in
2-4-6 Landau potential and gradient terms, as well as flexoelectric coupling,
inhomogeneous elastic strains and electrostriction are included in the present
analysis. Spatial distributions of the ionized donors, free electrons and holes
were found self-consistently using the effective mass approximation for the
respective densities of states. The proximity and size effect of the electron
and donor accumulation/depletion by thin stripe domains and cylindrical
nanodomains are revealed. In contrast to thick domain stripes and thicker
cylindrical domains, in which the carrier accumulation (and so the static
conductivity) sharply increases at the domain walls only, small nanodomains of
radius less then 5-10 correlation length appeared conducting across entire
cross-section. Implications of such conductive nanosized channels may be
promising for nanoelectronics.Comment: 39 pages, 11 figures, 3 tables, 4 appendice
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