Researchers use atomic layer epitaxy to create silicon chips

Warwick University researchers are hoping to use a new way of creating silicon-based chips to develop electronic cooling systems for spacecraft sensors.

The university has received a £1.7m grant from the EPSRC to continue for a further five years its research into manufacturing chips one atomic layer at a time.

This technique, known as atomic layer epitaxy, allows chip makers to combine silicon with other elements such as germanium, giving the chips new properties and functions.

These include enabling the chips to act as sensors, to process light signals, to collect energy or to be used in so-called spintronic computing, as well as making components run faster and with less power than traditional silicon ones.

The chips could also help to create very efficient electronic cooling systems, dubbed ‘cooltronics’ by the researchers. These could be used in X-ray sensors on spacecraft or in medical devices that need to be cooled to less than 1K to operate.

‘Rather than have a big fridge that cools a whole system, you just use electronics to cool the little bit of the system that’s critical,’ project leader Prof David Leadley told The Engineer.

‘We hope that if we get this right within this time period, we could have a device that will fly on a mission at some point.’

The idea behind cooltronics is to create a structure that can extract electrons from a circuit that have higher energy levels and replace them with less energetic ones, thereby lowering the temperature of the system.

Cooltronic devices have previously been created with metal-based structures, but the Warwick team hopes that using silicon will allow the chips to be integrated much more easily with other electronic components.

The team will begin by developing the general epitaxy technique to use it on a variety of pilot studies of silicon-based chips.

In particular, the researchers hope to make the different layers of silicon and germanium in the chips more well defined and to prevent smearing between them.

‘What we are developing here is a particular lower-temperature method of doing this growth, which means that there’s less of the smearing,’ said Leadley.

‘Once you get more abrupt interfaces, you can create structures that are much better controlled and then get things where you can modulate light particularly well,’ he added.