Atom-thick circuit breakthrough 'next revolution in electronics'

RMIT, CSIRO and Monash University lead international team in discovery of liquid metal production process

A new technique for creating ultra-thin electronic circuits has been discovered by researchers at RMIT’s School of Engineering.

The process, heralded as the "next revolution in electronics”, uses liquid metals to print integrated circuits that are only atoms thick.

“The fundamental technology of car engines has not progressed since 1920 and now the same is happening to electronics,” says RMIT’s Professor Kourosh Kalantar-zadeh. “The electronics industry has hit a barrier. Mobile phones and computers are no more powerful than five years ago.”

“That is why this new 2D printing technique is so important – creating many layers of incredibly thin electronic chips on the same surface dramatically increases processing power and reduces costs,” he added.

The RMIT School of Engineering led-breakthrough, which involved researchers from CSIRO, Monash University, North Carolina State University and the University of California, overcame the current limitations of chip production and paved the way for flexible electronics, Kalantar-zadeh said.

Hot chip

The technique uses gallium and indium, metals which have a low melting point. When liquid, the metals produce an atomically thin layer of oxide on their surface.

“It is this thin oxide which we use in our fabrication method,” explains Benjamin Carey, a researcher with RMIT and the CSIRO. “By rolling the liquid metal, the oxide layer can be transferred on to an electronic wafer, which is then sulphurised. The surface of the wafer can be pre-treated to form individual transistors.

“We have used this novel method to create transistors and photo-detectors of very high gain and very high fabrication reliability in large scale.”

Large wafers could now be produced that were around 1.5 nanometres in depth. To put that in context, a sheet of paper is around 100,000nm thick.

Previous techniques had proved unreliable, difficult to scale and only possible at very high temperatures of 550 degrees or more.

“None of the current technologies are able to create homogenous surfaces of atomically thin semiconductors on large surface areas that are useful for the industrial scale fabrication of chips,” Carey added.

Wafer Scale Two Dimensional Semiconductors from Printed Oxide Skin of Liquid Metals was published in Nature Communications this week.