267 research outputs found
Shot noise as a tool to probe an electron energy distribution
We discuss the possibility to employ the shot-noise measurements for the
analysis of the energy resolved ballistic currents. Coulomb interactions play
an essential role in this technique, since they lead to the
shot-noise-suppression level which depends on the details of the energy
profile.Comment: 7 pages, 2 figs; contribution to the Proceedings of EP2DS-14, Prague,
2001; to appear in Physica
Quantum suppression of shot noise in field emitters
We have analyzed the shot noise of electron emission under strong applied
electric fields within the Landauer-Buttiker scheme. In contrast to the
previous studies of vacuum-tube emitters, we show that in new generation
electron emitters, scaled down to the nanometer dimensions, shot noise much
smaller than the Schottky noise is observable. Carbon nanotube field emitters
are among possible candidates to observe the effect of shot-noise suppression
caused by quantum partitioning.Comment: 5 pages, 1 fig, minor changes, published versio
Shot-noise spectroscopy of energy-resolved ballistic currents
We investigate the shot noise of nonequilibrium carriers injected into a
ballistic conductor and interacting via long-range Coulomb forces. Coulomb
interactions are shown to act as an energy analyzer of the profile of injected
electrons by means of the fluctuations of the potential barrier at the emitter
contact. We show that the details in the energy profile can be extracted from
shot-noise measurements in the Coulomb interaction regime, but cannot be
obtained from time-averaged quantities or shot-noise measurements in the
absence of interactions.Comment: 7 pages, 4 figure
Self-consistent theory of shot noise in nondegenerate ballistic conductors
A self-consistent theory of shot noise in ballistic two-terminal conductors
under the action of long-range Coulomb correlations is presented. Analytical
formulas for the electron distribution function and its fluctuation along the
conductor, which account for the Coulomb correlations, have been derived. Based
upon these formulas, the current-noise reduction factor has been obtained for
biases ranging from thermal to shot-noise limits as dependent on two
parameters: the ratio between the length of the sample and the Debye screening
length \lambda=d/L_D and the applied voltage qU/k_BT. The difference with the
formulas for a vacuum diode is discussed.Comment: 21 pages, 11 figs, minor change
Shot-noise suppression by Fermi and Coulomb correlations in ballistic conductors
We investigate the injection of degenerate Fermi-Dirac electrons into a
multimode ballistic conductor under the space-charge limited regime. The
nonequilibrium current fluctuations were found to be suppressed by both Coulomb
and Fermi correlations. We show that the Fermi shot-noise suppression factor is
limited below by the value 2kT/epsilon_F, where T is the temperature and
epsilon_F the Fermi energy of the injected electrons. The Coulomb noise
suppression factor may attain much lower values epsilon_F/2qU, because of its
dependence on the applied bias U >> kT/q. The asymptotic behaviour of the
overall shot-noise suppression factor in a high degenerate limit was found to
be kT/qU, independently of the material parameters.Comment: 8 pages, 4 figures, minor changes, published versio
Coherent patterns and self-induced diffraction of electrons on a thin nonlinear layer
Electron scattering on a thin layer where the potential depends
self-consistently on the wave function has been studied. When the amplitude of
the incident wave exceeds a certain threshold, a soliton-shaped brightening
(darkening) appears on the layer causing diffraction of the wave. Thus the
spontaneously formed transverse pattern can be viewed as a self-induced
nonlinear quantum screen. Attractive or repulsive nonlinearities result in
different phase shifts of the wave function on the screen, which give rise to
quite different diffraction patterns. Among others, the nonlinearity can cause
self-focusing of the incident wave into a ``beam'', splitting in two ``beams'',
single or double traces with suppressed reflection or transmission, etc.Comment: RevTex, 4 pages, epsf.sty to insert figures, to appear in Phys.Rev.
Prospects of development of nanotechnologies
Nanotechnologies have prospects for development as the result of studying this field of science can be used in many fields of human activity [2-4]. Science itself nanotechnology is poorly understood, which is the basis of its relevance for today. Various devices and materials created with the help of nanotechnology are becoming a logical step towards improving technical systems and scientists predict the triumph of nanotechnology in the very near future, as they penetrate most of the branches of production
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