Negative capacitance is the key to reducing global energy consumption, say Aussie researchers

Reducing global energy consumption is part of a worldwide strategy for a more sustainable future. Now Australian electronics researchers have come up with a blueprint for how to do it, without having to make us switch our devices off altogether.

The researchers from four Australian universities that work collectively under the umbrella of the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), discovered that energy consumption in electronics and computers can be lowered significantly by using a kind of electrical conductivity known as negative capacitance.

The FLEET team presented their research at the International Electron Devices Meeting (IEDM) in San Francisco this week, showing how negative capacitance applied to topological transistors could effectively make them switch at a lower voltage, thereby reducing the amount of energy consumed by a device.

What’s a topological transistor? It’s the key to understanding the FLEET team’s findings. As a backgrounder, in a normal electronic device, transistors (or electronic switches) are turned on or off when electrical current is applied. Key to this process working are the materials used in the transistors – the insulators.

Semiconductors, like the silicon found in microchips, are insulators in that they don’t normally conduct electricity without an extra charge applied to them. This property allows run-of-the-mill field-effect transistors (FETs) to work, where a voltage charges a capacitor and the extra charge on the semiconductor allows the current to flow from source to drain.

However, FLEET researchers have pioneered a new type of transistor called a topological quantum field effect transistor (TQFET). This kind of transistor uses insulators called ‘topological insulators’ made from materials other than silicon. Rather than being uniform in their electrical conductance, topological insulators in TQFETs conduct electricity along their edges, but not in their interiors, to normal insulators that don’t conduct electricity.  

Credit: Dreamstime: Oleg Zhukov

The benefit of this is that TQFETs, like those made from bismuth, can switch at much lower voltages than conventional FETs when negative capacitators (from ferroelectric materials) are used to amplify an electric field, thus less energy is consumed in doing so.

The researchers say they’re some way off producing real working Negative Capacitance TQFETs (NC-TQFETs), but they estimate a bismuth-based NC-TQFET, using ferroelectric insulators, could result in a more than tenfold reduction in switching energy, when compared to that of a modern silicon-based FET.

What’s more, FLEET lead researcher, Monash University’s Professor Michael Fuhrer says further research could substantially improve on that: “More advanced ferroelectrics with larger remnant polarizations could enable switching at even lower energies,” he says.

Considering 8 percent of global electricity consumption is from information technology (ICT), so from computers and other devices, the implementation of the FLEET researchers’ findings could one day be transformational in greatly reducing global energy consumption.

The FLEET researchers will now continue their research into NC-TQFETs in the hope of one day bringing this technology to life in electronics.