The world's fastest electrometer
A new transistor is the world's most sensitive electrometer - it can even count single electrons flowing through a circuit. The detector could be used in tiny electronic circuits or work as an extremely light-sensitive sensor in microscopes and telescopes. Yale University's Daniel E. Prober says the new device is 1,000 times faster than previous electrometers and even a million times faster than other single-electron transistors (Science 22 May 1998). "Single-electron transistors have been on the market for a few years. But our lab has developed a new type, the Radio Frequency Single Electron Transistor (RF-SET), which can still measure charges one 15 millionth the charge on an electron. He covers an enormous range," he says.
At the moment, however, the RF-SET only works at temperatures just above absolute zero. But while conventional single-electron transistors usually only achieve measuring rates of up to one kilohertz (1000 measurements per second), the RF-SET manages up to 100 megahertz. With such high resolution, background charge motion noise is negligible.
The potential range of applications of the RF-SET is enormous. Because it can detect photons ranging from X-rays to microwaves, it would be a suitable replacement for CCD detectors when studying very faint stars or galaxies. In Prober's opinion, it could also serve as a spectrometer, determining the chemical composition of the stars.
Microelectronics also has a need for an extremely sensitive electrometer. On the edge of the quantum world, strange processes such as the tunnel effect are taking place, which make it necessary to carry out basic research with the appropriate instruments.
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