"The Worlds Smallest Shielded Room: Encasing a Single Electron Transistor in a Nano-Faraday Cage"

William H. Huber, Neil M. Zimmerman:
Electricity Division, EEEL
Daniel E. Josell: Metallurgy Division, MSEL

Over the past decade, a class of devices has been developed based upon the phenomenon of single electron tunneling (SET). These devices exploit the quantized nature of an electron's charge to, among other uses, detect minute fractions of an electronic charge or shuttle individual electrons across a sample with exquisite precision. SET devices therefore offer the possibility of constructing a long sought after electrical current standard simply by counting individual electrons. At present however, a SET current standard is out of reach because the characteristics of these devices are not stable over time. This instability is caused by small bundles of charge located near the sample which slowly wander, even at the exceptionally low operating temperatures of the SET devices. To attempt to shield the devices from the mobile bundles, we have constructed the World's first nano-Faraday cage and encased individual SET devices entirely inside the tiny enclosures. We have found that nano-Faraday cages provide superior environmental and electrostatic discharge protection for the encased SET devices. At present, the cages are unfortunately equipped with their own bundles of mobile stray charge. We are however researching alternative cage fabrication techniques to drastically decrease the overall amount of stray charge and hence decrease the instability of single electron tunneling devices.