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The characteristics of electrical contacts have long attracted the
attention of researchers since these contacts are used in every
electrical and electronic device. Earlier studies generally
considered electrical contacts of large dimensions, having regions
of current concentration with diameters substantially larger than
the characteristic dimensions of the material: the interatomic
distance, the mean free path for electrons, the coherence length in
the superconducting state, etc. [110]. The development of
microelectronics presented to scientists and engineers the task of
studying the characteristics of electrical contacts with
ultra-small dimensions. Characteristics of point contacts such as
mechanical stability under continuous current loads, the magnitudes
of electrical fluctuations, inherent sensitivity in radio devices
and nonlinear characteristics in connection with electromagnetic
radiation can not be understood and altered in the required way
without knowledge of the physical processes occurring in contacts.
Until recently it was thought that the electrical conductivity of
contacts with direct conductance (without tunneling or
semiconducting barriers) obeyed Ohm's law. Nonlinearities of the
current-voltage characteristics were explained by joule heating of
the metal in the region of the contact. However, studies of the
current-voltage characteristics of metallic point contacts at low
(liquid helium) temperatures [142] showed that heating effects were
negligible in many cases and the nonlinear characteristics under
these conditions were observed to take the form of the energy
dependent probability of inelastic electron scattering, induced by
various mechanisms.
There is a growing understanding that the progress of the
conventional silicon technology will reach its physical,
engineering and economic limits in near future. This fact, however,
does not mean that progress in computing will slow down. What will
take us beyond the silicon era are new nano-technologies that are
being pursued in university and corporate laboratories around the
world. In particular, molecular switching devices and systems that
will self-assemble through molecular recognition are being designed
and studied. Many labora tories are now testing new types of these
and other reversible switches, as well as fabricating nanowires
needed to connect circuit elements together. But there are still
significant opportunities and demand for invention and discovery be
fore nanoelectronics will become a reality. The actual mechanisms
of transport through molecular quantum dots and nanowires are of
the highest current ex perimental and theoretical interest. In
particular, there is growing evidence that both electron-vibron
interactions and electron-electron correlations are impor tant.
Further progress requires worldwide efforts of trans-disciplinary
teams of physicists, quantum chemists, material and computer
scientists, and engineers."
There is a growing understanding that the progress of the
conventional silicon technology will reach its physical,
engineering and economic limits in near future. This fact, however,
does not mean that progress in computing will slow down. What will
take us beyond the silicon era are new nano-technologies that are
being pursued in university and corporate laboratories around the
world. In particular, molecular switching devices and systems that
will self-assemble through molecular recognition are being designed
and studied. Many labora tories are now testing new types of these
and other reversible switches, as well as fabricating nanowires
needed to connect circuit elements together. But there are still
significant opportunities and demand for invention and discovery be
fore nanoelectronics will become a reality. The actual mechanisms
of transport through molecular quantum dots and nanowires are of
the highest current ex perimental and theoretical interest. In
particular, there is growing evidence that both electron-vibron
interactions and electron-electron correlations are impor tant.
Further progress requires worldwide efforts of trans-disciplinary
teams of physicists, quantum chemists, material and computer
scientists, and engineers."
The characteristics of electrical contacts have long attracted the
attention of researchers since these contacts are used in every
electrical and electronic device. Earlier studies generally
considered electrical contacts of large dimensions, having regions
of current concentration with diameters substantially larger than
the characteristic dimensions of the material: the interatomic
distance, the mean free path for electrons, the coherence length in
the superconducting state, etc. [110]. The development of
microelectronics presented to scientists and engineers the task of
studying the characteristics of electrical contacts with
ultra-small dimensions. Characteristics of point contacts such as
mechanical stability under continuous current loads, the magnitudes
of electrical fluctuations, inherent sensitivity in radio devices
and nonlinear characteristics in connection with electromagnetic
radiation can not be understood and altered in the required way
without knowledge of the physical processes occurring in contacts.
Until recently it was thought that the electrical conductivity of
contacts with direct conductance (without tunneling or
semiconducting barriers) obeyed Ohm's law. Nonlinearities of the
current-voltage characteristics were explained by joule heating of
the metal in the region of the contact. However, studies of the
current-voltage characteristics of metallic point contacts at low
(liquid helium) temperatures [142] showed that heating effects were
negligible in many cases and the nonlinear characteristics under
these conditions were observed to take the form of the energy
dependent probability of inelastic electron scattering, induced by
various mechanisms.
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