STM image reveals honeycomb structure of germanene. Image credit: M E Dávila et al.
Germanene does not exist in nature and is made up of a single layer of germanium atoms. It is expected to exhibit impressive electrical and optical properties and could be widely integrated across the electronics industry in the future.
First proposed in 2009, the material has, up until now, remained elusive. Since then, graphene has been developed further whilst other two-dimensional materials, such as graphene’s silicon cousin – silicene, have been synthesized.
Much like silicene, the proposed method for synthesizing germanene is to deposit individual atoms of germanium onto a substrate under high temperatures and in an ultra-high vacuum.
“Following our synthesis of graphene’s other cousin, silicene, we thought it natural to try and produce germanene in the same way, by depositing germanium onto a silver substrate. This attempt failed, so I decided to switch to a gold substrate,” said Prof Guy Le Lay of Aix-Marseille University, who is the senior author of a paper published in the New Journal of Physics.
After depositing the germanium atoms onto a gold substrate, Prof Le Lay’s team was able to confirm that the material was in fact germanene. The material was also observed under a scanning tunneling microscope, which revealed the characteristic honeycomb structure of a 2D material.
The scientists said the unique properties of germanene could make it a robust two-dimensional topological insulator, particularly up to room temperature, opening up the possibility of using the material in quantum computing.
“An important aspect of our study is that we have increased the lego of 2D materials that we can use to build a whole host of artificial solid materials with a wide range of differing properties,” said co-author Prof Angel Rubio of the University of the Basque Country.
“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 characterize the electronic properties of the material,” Prof Le Lay concluded.
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M E Dávila et al. 2014. Germanene: a novel two-dimensional germanium allotrope akin to graphene and silicene. New Journal of Physics, vol. 16; doi: 10.1088/1367-2630/16/9/095002