The more things change, the more things stay the same. Early electronic devices used a spark gap. These have been almost completely replaced with tubes and then semiconductor devices such as transistors. However, transistors will soon reach a theoretical limit on how small they can be which is causing researchers to find the next thing. If the Royal Melbourne Institute of Technology has its way, we’ll go back to something that has more in common with a spark gap than a conventional transistor. You can find the source paper on the Nano Papers website although the text is behind a paywall.
The transistor uses metal, but instead of a semiconductor channel — which is packed with atoms that cause collisions as electrons flow through the channel — the new device uses an air gap. You might well think that if fewer atoms in the channel are better, why not use a vacuum?
You’d be right. The problem is, producing a device in a vacuum-sealed package would make the devices larger than conventional transistors. Instead, the new devices use a nanoscale gap between two metal points. The gap is so small the electrons can pass almost as freely as they do in a vacuum. How small is the gap? Just a few tens of nanometers.
Although some reports claim the devices don’t use any semiconductor material, in fact, the practical devices used a gate made of silicon underneath the channel. The source and drain are pointy pieces of metal where the points almost touch and the gate runs beneath the gap which is the channel.
Don’t get us wrong. The mechanism isn’t like that of a spark gap, instead it’s some kind of tunneling mechanism. But we couldn’t help but find it amusing that maybe electronics will again rely on magic air gaps. Like all the research you read about, you never know if this is the next big thing or a dead end. More likely, it’s a stepping stone that will lead to something even more amazing.