Newswise — Researchers
from the University of South Florida, the University
of Chicago and the Russian Academy of Sciences (Moscow)
have recently developed the principles of operation
and completed an experimental testing of a single
molecule for use as a diode. A paper explaining their
research has just been accepted for publication in Physical
Review Letters by the American Physical Society.
“Single molecule diodes are the fundamental building
blocks of an emerging technology called ‘nanoelectronics,'
a field that holds promise for application in all
kinds of electronic devices, from cell phones to
sensors,” explained Ivan Oleynik, a physics professor
at USF. “Molecular diodes could be built a thousand
times smaller than those in use now.”
Computer industry execs might start breathing easier
because their biggest fear - that smaller and faster
devices will eventually come to an end because silicon
microchips will get so small that eventually they
will contain too few silicon atoms to work - might
be lessened as advancements in molecular electronics
come to the rescue.
“Molecular electronics is enabling an area of nanoscience
and technology that holds promise for the next generation
of electronic devices,” said Oleynik. “Single molecular
electronic devices rely on organic molecules with
electronic responses tailored through synthetic organic
chemistry.”
Functioning at under several nanometers (a nanometer
is a billionth of a meter), the molecular diode studied
by the team of researchers acted as a rectifier (diode)
because of the chemical asymmetry in different parts
of an organic molecule comprised of both thiophene
and thiazole. As a major component of electric circuitry,
a diode is responsible for conducting electrical
current by working something like a light switch,
but allows current to flow only forward. The first
diodes were large vacuum tubes, and most modern diodes
are based on solid-state semiconductors.
“Molecular nanoelectronics is an exciting area of
science not only because of its potential but because
it is highly interdisciplinary, combining physics,
chemistry, materials science, computational science
and engineering,” said Oleynik.
The team's most recent finding and the basis for
their publication was an explanation of how the intrinsic
chemical asymmetry of “designer” molecules results
in rectification of electrical current. The left
and right parts of the organic molecule interact
differently with electrons that “tunnel” through
the molecule. Importantly, the electronic interactions
with the left and right parts of the molecule respond
differently to the change of the polarity of applied
voltage.
The potentially bright future of molecular electronic
technology is calculated on an ability to control
molecular structure. Much of the work is yet empirical
and involves “chemical intuition” as a driving force
in molecular design as well as the applications of
molecular devices.
“The next step is in developing the virtual integrated
prototyping of molecular devices and optimizating
their electronic functionalities by choosing the
most appropriate chemical composition that has desirable
electronic properties,” explained Olynik. “This will
require the development of a scientific understanding
of electron transport through molecules as well as
the introduction of new concepts and new language
to explain such transport.”
Success in pioneering the field of molecular electronics
would mean new life could be breathed into Moore's
Law, the prediction made by Intel's Gordon Moore
in 1965 that the density of transistors on a chip
would double very 18-24 months. While Moore's observation
has been true, everyone in the industry knows that
there has always been a limit to the number of atoms
that would render a device smaller, cheaper, faster
but still operable. New technology that would “expand” the
limits of microelectronics has been a continuing
quest.
“Molecular electronics is a viable alternative that
may reach the ultimate limit of miniaturization – one
molecule per transistor, diode or switch,” believes
Oleynik.
The University of South Florida is on track to become
one of the nation's top 50 public research universities.
USF received more than $287 million in research contracts
and grants last year, and it is ranked by the National
Science Foundation as one of the nation's fastest
growing universities in terms of federal research
and development expenditures. The university has
a $1.1 billion annual budget and serves nearly 43,250
students on campuses in Tampa, St. Petersburg, Sarasota/Manatee
and Lakeland. In 2005, USF entered the Big East athletic
conference.
|
