Scientists make armour for 2D systems
Research promises lower-energy alternatives for electronics and optoelectronics by harnessing 2D semiconducting materials such as WS2
An international team of scientists has invented the equivalent of body armour for fragile quantum systems, which will make them robust enough to be used as the basis for a new generation of low-energy electronics.The scientists applied the armour by gently squashing droplets of liquid metal gallium onto the 2D materials, coating them with Ga2O3.
Protection is crucial for 2D materials as they are easily damaged by conventional layering technology, said Matthias Wurdack, who is the lead author of the group’s publication in Advanced Materials.
“The protective coating basically works like a body armour for the atomically-thin material, it shields against high-energy particles, which would cause a large degree of harm to it, while fully maintaining its optoelectronic properties and its functionality,” said Wurdack, a PhD student in the Nonlinear Physics Centre (NLPC) of the Research School of Physics, and the FLEET ARC Centre of Excellence.
The new technique opens the way for an industry based on ultra-thin electronics to expand, said leader of the research team, Elena Ostrovskaya, also from NLPC and FLEET. “2D materials have extraordinary properties such as extremely low resistance or highly efficient interactions with light.”
Eight percent of global electricity consumption in 2020, was due to information technologies, including computers, smartphones and large data centres of tech giants such as Google and Amazon. That figure is projected to double every decade as demand for AI services and smart devices skyrockets.
However, this work promises lower-energy alternatives for electronics and optoelectronics, by harnessing the superior performance of 2D semiconducting materials, such as WS2, which was used in this study.
Using 2D materials to make more efficient devices will have advantages beyond reduced carbon emissions, says Wurdack.
“2D technology could also enable super-efficient sensors on space craft, or processors in Internet of Things devices that are less limited by battery life.”
The team created their protective layer by exposing to air a droplet of liquid gallium, which immediately formed a perfectly even layer of Ga2O3 on its surface a mere three nanometers thick.
By squashing the droplet on top of the 2D material with a glass slide, the gallium oxide layer can be transferred from the liquid gallium onto the material’s entire surface, up to centimetres in scale.
Because this ultrathin Ga2O3 is an insulating amorphous glass, it conserves the optoelectronic properties of the underlying 2D semiconductor. The Ga2O3 glass can also enhance these properties at cryogenic temperatures and protects well against other materials deposited on top. This allows the fabrication of sophisticated, layered nanoscale electronic and optical devices, such as light emitting diodes, lasers and transistors.
“We’ve generated a nice alternative to existing technology that can be scaled for industry applications,” Wurdack said.
“We hope to find industry partners to work with us to develop a protective layer printer based on this technology, that can go into any lab, like a lithography machine.”
Pictured from left to right above are the FLEET ANU researchers Eliezer Estrecho, Matthias Wurdack, and Tinghe Yun
'Ultrathin Ga2O3 Glass: A Large‐Scale Passivation and Protection Material for Monolayer WS2' by M Wurdack et al; Advanced Materials in December 2020