A new one atom-thick flat material that could upstage the wonder material graphene and advance digital technology has been discovered by scientists led by an Indian-origin physicist in US. The material is made up of silicon, boron and nitrogen – all light, inexpensive and Earth abundant elements – and is extremely stable, a property many other graphene alternatives lack.
“We used simulations to see if the bonds would break or disintegrate – it did not happen,” said Madhu Menon, a physicist at the University of Kentucky in US. “We heated the material up to 1,000-degree Celsius and it still did not break,” said Menon, who worked with scientists including those from the Institute for Electronic Structure and Laser (IESL) in Greece.
Using state-of-the-art theoretical computations, Menon and his colleagues demonstrated that by combining the three elements, it is possible to obtain a one atom-thick, truly two-dimensional (2D) material with properties that can be fine-tuned to suit various applications beyond what is possible with graphene.
Graphene with many unique properties has one downside: it is not a semiconductor and therefore disappoints in the digital technology industry. Subsequent search for new 2D semiconducting materials led researchers to a new class of three-layer materials called transition-metal dichalcogenides (TMDCs).
TMDCs are mostly semiconductors and can be made into digital processors with greater efficiency than anything possible with silicon. However, these are much bulkier than graphene and made of materials that are not necessarily Earth abundant and inexpensive.
Searching for a better option that is light, Earth abundant, inexpensive and a semiconductor, the team led by Menon studied different combinations of elements from the first and second row of the periodic table.
Although there are many ways to combine silicon, boron and nitrogen to form planar structures, only one specific arrangement of these elements resulted in a stable structure. The atoms in the new structure are arranged in a hexagonal pattern as in graphene, but that is where the similarity ends.
The three elements forming the new material all have different sizes; the bonds connecting the atoms are also different. As a result, the sides of the hexagons formed by these atoms are unequal, unlike in graphene. The new material is metallic, but can be made semiconducting easily by attaching other elements on top of the silicon atoms.
Presence of silicon also offers the exciting possibility of seamless integration with the current silicon-based technology, allowing the industry to slowly move away from silicon instead of eliminating it completely, all at once.
Feature image source: Madhu Menon