Experts synthesise 'graphene's cousin'

A team of European research specialists has become one of the first groups to synthesise the two-dimensional (2D) nanomaterial germanene, according to a study published today in the New Journal of Physics.

The breakthrough was made in parallel with an independent team from China who has reported evidence that germanene has been synthesised onto a platinum substrate, the Institute of Physics said.

“The synthesis of germanene is just the very beginning of a long quest

Study author Guy Le Lay

Germanene, which exhibits similar properties to other nanomaterials, is being dubbed the ’cousin of graphene’ as it consists of a single layer of germanium atoms.

The European research team expects germanene to exhibit impressive electrical and optical properties - suggesting it could be widely integrated across the electronics industry in the future.

According to study co-author Guy Le Lay, from Aix-Marseille University, France, graphene is not suited to digital logic applications because it has no gap, unlike silicene, and now germanene.

“There are also some claims that germanene could be a high temperature superconductor,” he said.

Similar to the 2D material silicene, the proposed method for synthesising germanene is to deposit individual germanium atoms onto a substrate under high temperatures and in an ultra-high vacuum, the researchers said.

Le Lay said his research team discovered that gold could be used as a substrate, as opposed to platinum.

“Following our synthesis of graphene’s other cousin, silicene, we thought it natural to try and produce germanene in the same way, by despositing germanium onto a silver substrate,” Le Lay said.

“This attempt failed, so I decided to switch to a gold substrate.”

Using a combination of spectroscopy and density functional theory (DFT) calculations, which was used to investigate the electronic structure of the material, the European team confirmed that the material was germanene.

The material was also observed under a scanning tunnelling microscope, which revealed the characteristic honeycomb structure of a 2D material, the researchers said.

Looking ahead, the researchers have said it may be possible for germanene to be grown on thin gold films sitting on top of a flexible substrate, which would be cheaper than platinum, and could allow germanene to be synthesised on a larger scale.

“The synthesis of germanene is just the very beginning of a long quest. Indeed, success in the synthesis was not easy to achieve and quite demanding. A considerable amount of work is now needed to further characterise the electronic properties of the material,” Le Lay said.

As silicene is still in its infancy, germanene can be considered no more than a new-born, Le Lay told LaboratoryTalk.

“We have hints of its electronic properties from preliminary measurements, but we know much more from theoretical calculations from Angel’s Rubio group in San Sebastian, Spain, and from many other independant groups.

“These calculations are generally quite reliable,” he said.

A full account of the study can be found here.