New '1/f noise' discovery promises to improve
semiconductor-based sensors.
More sensitive sensors and detectors based on semiconductor
electronics could result from new findings by researchers from the
United States, Norway and Russia.
Their research has yielded a decisive step in
identifying the origin of the universal "one-over-f" (1/f) noise
phenomenon; “f” stands for "frequency."
"One-over-f noise appears almost everywhere, from
electronic devices and fatigue in materials to traffic on roads, the
distribution of stars in galaxies, and DNA sequences," said Valerii
Vinokour or Argonne's Materials Science Division. "Finding the common
origin of one-over-f noise in its many forms is one of the grand
challenges of materials physics. Our theory establishes the origin and
lower limit to one-over-f noise in semiconductor electronics, helping
to optimize detectors for commercial application."
Illustration of a Coulomb glass
system: Electrons (red) in a random landscape, interacting with
each other (yellow-orange lines). Noise of the resistance of the
system is created by collective "hopping" of the electrons (green
arrow).
Noise is a fluctuation in time, a deviation
from the average. Humans and other animals carry a common example in
their heartbeats, where 1/f noise can be detected as a deviation from
normal pulse. In nanomaterials, such as the tiny circuits in
semiconductor electronics, the noise generated by the random motion of
a single electron can be devastating, since there are so few electrons
in the system.
Vinokur and his team showed that the 1/f noise in
doped semiconductors, the platform for all modern electronics,
originates in the random distribution of impurities and the mutual
interaction of the many electrons surrounding them. These two
ingredients - randomness and interaction - trap electrons in the
Coulomb glass, a state like window glass where electrons move by
hopping from one random location to another. 1/f noise arises from the
electrons; hopping motion. After discovering the theoretical
connection between 1/f noise and formation of the Coulomb glass,
Vinokur and his collaborators confirmed it with large-scale computer
simulations: suppression of the interactions was found to remove the
Coulomb glass behavior and 1/f noise.
“Our results," Vinokour said, "establish that
one-over-f noise is a generic property of Coulomb glasses and,
moreover, of a wide class of random interacting systems and phenomena
ranging from mechanical properties of real materials and electric
properties of electronic devices to fluctuations in the traffic of
computer networks and the Internet.”
These research findings were published in the May
11 issue of Physical Review Letters.
The nation's first national laboratory,
Argonne National
Laboratory conducts basic and applied scientific research
across a wide spectrum of disciplines, ranging from high-energy
physics to climatology and biotechnology. Since 1990, Argonne has
worked with more than 600 companies and numerous federal agencies
and other organizations to help advance America's scientific
leadership and prepare the nation for the future. Argonne is
managed by UChicago Argonne, LLC for the U.S. Department of
Energy's Office of Science.
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