May 10, 2007
The universe is a noisy place – from traffic growling along roads to the random fluctuations in DNA sequences and from the distribution of stars in galaxies to the hissy fit that is electronic noise. One thing all these forms of noise have in common is they are related by the phrase “One-over-f”, the reciprocal of frequency.
A new understanding of “1/f” has emerged from a collaboration between scientists in Norway, Russia, and the USA. Their work could lead to more sensitive sensors and detectors based on semiconductor electronics.
According to materials scientist Valerii Vinokour of Argonne National Laboratory, Illinois, “Finding the common origin of one-over-f noise in its many forms is one of the grand challenges of materials physics,” he says. He and his colleagues have developed a new theory of 1/f noise establishes its origin and lower limit in semiconductor electronics, which could help developers optimize detectors for commercial applications.
Noise is nothing more than timely fluctuations, deviations from the average. In microelectronics, noise is generated by random fluctuations of electrons. Vinokur and his colleagues report in the May 11 issue of the science journal Phys Rev Lett how 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 – lead to electrons being trapped in a Coulomb glass state in which electrons hop randomly from point to point.
“Our results,” Vinokour explains, “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.”