One of the ultimate goals in nanotechnology is to encode a bit of information on a single electron and process it. This goal has moved a step closer with the demonstration of a single-electron device made of silicon that operates at room temperature.

Katsuhiko Nishiguchi of NTT Basic Research Laboratories in Japan and co-workers built a single-electron circuit in which electrons are transferred one by one with a ‘turnstile’ and then detected with an extremely sensitive electrometer. The circuit offers both fast single-electron transfer (less than 10 ns) and storage times of more than 10,000 seconds, and it has been used to make a multilevel memory and a digital-to-analogue converter.

The heart of the device is a single-electron box, which has to be small enough (less than 10 nm) so that the energy needed to add another electron is greater than the thermal energy at room temperature. Two field-effect transistors control the movement of electrons in and out of the box. The 50-nm technology used to make the device should be commercially available by 2009.