Information Technology Reference
In-Depth Information
- Noise-free single-electron processes
- Specific molecular mechanisms of signal transmission, which may allow to
create logically more complex primitives
The beginning of the 1970s of the last century coincided with the molecular
boom in electronics. In 1974, the IBM scientists Ari Aviram and Mark Ratner, who
worked at Northwestern University in Illinois, published a work entitled “Molec-
ular Rectifier.” For the first time, it was attempted to use a rigorous physical
approach for evaluating the possibility to construct a molecular system with
unidirectional electron conductivity: a molecule consisting of two molecular frag-
ments with different electron affinities and placed between two electrodes. If
electric potential is applied to electrodes in one direction, then the closest molecular
fragment captures an electron from the electrode and transfers it to another frag-
ment which, in its turn, passes it to the second electrode. When the electric potential
is applied in the opposite direction, no electron transfer is observed. Aviram and
Ratner were the first to propose a specific molecule which they believed could be
used as one of the basic elements of electronic circuits.
Also in the beginning of 1974 Michael Conrad at the Wayne University in
Detroit conceived a molecular information processing system based on the princi-
ple of a specialized neural network (see next chapter for details).
But the greatest progress in the development of this new field of research, which
people started to call “molecular electronics,” was due to Forrest Carter, a scientist
at the US Naval Research Laboratory. Over the course of many years, he considered
the physical principles of molecular systems that could be used as primitives for
information processing devices. Moreover, it was Forrest Carter who tried to unite
the scientists who were seeking ways to use molecular objects for creating elec-
tronic devices. In 1982 and 1987 he organized two international conferences on
molecular electronic devices. Unfortunately, the third conference he had organized
was held in July 1988 after his death.
As a result, activity and expectations in this new field of research were high in
the 1980s and early 1990s. For example, supporting the widespread belief in the
importance of molecular primitives for the further development of information
processing, Alan Berman, director of research at the US Naval Research Labora-
tory, declared at the Workshop on Molecular Electronic Devices in 1981 [25]:
“I think the possible advantages of a computer based on molecular level of
electronics are fairly obvious. When one evaluates whether one should invest one's
time, assets or career in this field, one must consider the following points:
In going from a modern day two-dimensional (2-D) computer to three-
dimensional (3-D) molecular configuration, wiring costs must be significantly
decreased and fabrication more fully automated, or the device will not be econom-
ically feasible.
By reducing the switching elements to molecular size the memory density could
be increased by several orders of magnitude and power input decreased very
significantly.
Three-dimensional construction plus switching elements of molecular size could
enhance computer speed by several orders of magnitude. To use this speed, faster
