4,193 research outputs found
Statistical properties of spectral fluctuations for a quantum system with infinitely many components
Extending the idea formulated in Makino {\it{et al}}[Phys.Rev.E
{\bf{67}},066205], that is based on the Berry--Robnik approach [M.V. Berry and
M. Robnik, J. Phys. A {\bf{17}}, 2413], we investigate the statistical
properties of a two-point spectral correlation for a classically integrable
quantum system. The eigenenergy sequence of this system is regarded as a
superposition of infinitely many independent components in the semiclassical
limit. We derive the level number variance (LNV) in the limit of infinitely
many components and discuss its deviations from Poisson statistics. The slope
of the limiting LNV is found to be larger than that of Poisson statistics when
the individual components have a certain accumulation. This property agrees
with the result from the semiclassical periodic-orbit theory that is applied to
a system with degenerate torus actions[D. Biswas, M.Azam,and S.V.Lawande, Phys.
Rev. A {\bf 43}, 5694].Comment: 6 figures, 10 page
Semiconductor-enriched single wall carbon nanotube networks applied to field effect transistors
Substantial progress on field effect transistors "FETs" consisting of
semiconducting single wall carbon nanotubes "s-SWNTs" without detectable traces
of metallic nanotubes and impurities is reported. Nearly perfect removal of
metallic nanotubes is confirmed by optical absorption, Raman measurements, and
electrical measurements. This outstanding result was made possible in
particular by ultracentrifugation (150 000 g) of solutions prepared from SWNT
powders using polyfluorene as an extracting agent in toluene. Such s-SWNTs
processable solutions were applied to realize FET, embodying randomly or
preferentially oriented nanotube networks prepared by spin coating or
dielectrophoresis. Devices exhibit stable p-type semiconductor behavior in air
with very promising characteristics. The on-off current ratio is 10^5, the
on-current level is around 10 A, and the estimated hole mobility is larger
than 2 cm2 / V s
Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing
High quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10−3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10−4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm2. Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes
Simplicity of eigenvalues in the Anderson model
We give a simple, transparent, and intuitive proof that all eigenvalues of
the Anderson model in the region of localization are simple
The repulsion between localization centers in the Anderson model
In this note we show that, a simple combination of deep results in the theory
of random Schr\"odinger operators yields a quantitative estimate of the fact
that the localization centers become far apart, as corresponding energies are
close together
Decorrelation estimates for the eigenlevels of the discrete Anderson model in the localized regime
The purpose of the present work is to establish decorrelation estimates for
the locally renormalized eigenvalues of the discrete Anderson model near two
distinct energies inside the localization region. In dimension one, we prove
these estimates at all energies. In higher dimensions, the energies are
required to be sufficiently far apart from each other
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