AsianScientist (Aug. 20, 2015) – Researchers have successfully fabricated the tin version of 2D wonder material graphene—a material called stanene. Their results, published in Nature Materials, pave the way for future investigation of stanene’s interesting predicted properties such as topological superconductivity and near-room temperature quantum anomalous Hall effect.
Research into ultrathin or 2D materials has intensified in recent years, not least since the discoverers of graphene won the 2010 Nobel Prize in physics.
“Similar to graphene, other 2D group-IV materials including silicene, germanene and stanene have attracted enormous interest because of their exotic electronic properties,” study corresponding author Professor Jia Jin-Feng told Asian Scientist Magazine.
“Stanene and its derivatives could support a large-gap 2D quantum spin Hall state and thus enable the dissipationless electric conduction at room temperature. Moreover, stanene could also provide enhanced thermoelectricity, topological superconductivity and the near-room-temperature quantum anomalous Hall.”
However, unlike graphene where monolayers can be obtained by simply using sticky tape, growing atom-thin layers of stanene has proven extremely difficult. Moreover, grey tin, the bulk form of stanene, does not exist at room temperature.
To overcome these challenges, Jia and his team at the Shanghai Jiao Tong University grew stanene by molecular beam epitaxy (MBE) in an ultrahigh vacuum. As the substrate used to grow thick films of grey tin was not suitable for growing stanene, the researchers also had to find an alternative, finally selecting bismuth telluride (Bi2Te3).
“For thick grey tin film, indium antimonide (InSb) is the best substrate. However, stanene cannot grow on InSb,” Jia explained.
Another challenge was the characterization of the ultrathin tin film, required to prove that what the researchers had synthesized was truly stanene.
“It took us almost two years to characterize the atomic and electronic properties of stanene. We used a range of techniques, including in situ low temperature scanning tunnelling microscopy, in-lab photoemission spectroscopy and synchrotron-based photoemission spectroscopy to confirm that our film is stanene,” Jia said.
One of the major advantages of stanene will be its energy-saving properties; it is predicted to be able to conduct electricity without losing energy as heat (superconductivity) even at room temperature.
“Now that we have the ability to grow stanene, we have to managed to confirm its unique properties as predicted by theory. However, this research is still at a fundamental stage and it will be a long time before the technology is industry ready,” Jia added.
As the current findings on the electronic structure of stanene are influenced by the presence of the substrate, the researchers next hope to be able to study stanene in isolation.
The article can be found at: Zhu et al. (2015) Epitaxial Growth of Two-Dimensional Stanene.
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Copyright: Asian Scientist Magazine; Photo: Shutterstock.
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