903 research outputs found
Ambipolar Graphene Field Effect Transistors by Local Metal Side Gates
We demonstrate ambipolar graphene field effect transistors individually
controlled by local metal side gates. The side gated field effect can have
on/off ratio comparable with that of the global back gate, and can be tuned in
a large range by the back gate and/or a second side gate. We also find that the
side gated field effect is significantly stronger by electrically floating the
back gate compared to grounding the back gate, consistent with the finding from
electrostatic simulation.Comment: 4 pages, 3 figure
Fermion Particle Production in Dynamical Casimir Effect in a Three Dimensional Box
In this paper we investigate the problem of fermion creation inside a three
dimensional box. We present an appropriate wave function which satisfies the
Dirac equation in this geometry with MIT bag model boundary condition. We
consider walls of the box to have dynamic and introduce the time evolution of
the quantized field by expanding it over the 'instantaneous basis'. We explain
how we can obtain the average number of particles created. In this regard we
find the Bogliubove coefficients. We consider an oscillation and determine the
coupling conditions between different modes that can be satisfied depending on
the cavity's spectrum. Assuming the parametric resonance case we obtain an
expression for the mean number of created fermions in each mode of an
oscillation and their dynamical Casimir energy.Comment: 5 pages, no figur
Zero area singularities in general relativity and inverse mean curvature flow
First we restate the definition of a Zero Area Singularity, recently
introduced by H. Bray. We then consider several definitions of mass for these
singularities. We use the Inverse Mean Curvature Flow to prove some new results
about the mass of a singularity, the ADM mass of the manifold, and the capacity
of the singularity.Comment: 13 page
Synthetic Graphene Grown by Chemical Vapor Deposition on Copper Foils
The discovery of graphene, a single layer of covalently bonded carbon atoms,
has attracted intense interests. Initial studies using mechanically exfoliated
graphene unveiled its remarkable electronic, mechanical and thermal properties.
There has been a growing need and rapid development in large-area deposition of
graphene film and its applications. Chemical vapour deposition on copper has
emerged as one of the most promising methods in obtaining large-scale graphene
films with quality comparable to exfoliated graphene. In this chapter, we
review the synthesis and characterizations of graphene grown on copper foil
substrates by atmospheric pressure chemical vapour deposition. We also discuss
potential applications of such large scale synthetic graphene.Comment: 23 pages, 4 figure
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