Turnstile to tinier future

Two Cambridge physicists have created a counter that acts as a turnstile for single electrons.

The delicate technology could be used in a host of electronics applications such as multi-level memory circuits and highly sensitive detectors.

As electronics is increasingly miniaturised, experts are looking to nano-metre scales as the way of the future.

The research by Haroon Ahmed and Nick Stone at the Microelectronics Research Centre, University of Cambridge, was published in the journal, Applied Physics Letters.

The scientists built a tiny multiple-tunnel junction (MTJ) on highly doped silicon nanowire that, through a series of barriers and islands, can move electrons about one by one.

They then used a second MTJ to keep count. It does this by registering changes in a detector circuit every time an electron enters or leaves. This is logged and added to the previous output stored in the detector.

The device is cooled to 4.2K to function but because its fabrication does not involve any advances in the lithography techniques used to build semiconductor circuits, it could have great potential.