Water could play major role in graphene nanoelectronics

WASHINGTON - According to a new study by researchers at Rensselaer Polytechnic Institute, water can be used to tune the band gap of the nanomaterial graphene, opening the door to new graphene-based transistors and nanoelectronics.

Nikhil Koratkar and his research team were able to create a band gap in graphene - a critical prerequisite to creating graphene transistors.

Transistors are devices that can be switched “on” or “off” to alter an electrical signal. Computer microprocessors are comprised of millions of transistors made from the semiconducting material silicon, for which the industry is actively seeking a successor.

Koratkar’s team demonstrated how to open a band gap in graphene based on the amount of water they adsorbed to one side of the material, precisely tuning the band gap to any value from 0 to 0.2 electron volts.

This effect was fully reversible and the band gap reduced back to zero under vacuum.

“Graphene is prized for its unique and attractive mechanical properties. But if you were to build a transistor using graphene, it simply wouldn’t work as graphene acts like a semi-metal and has zero band gap,” said Koratkar.

“Graphene is a zero band gap material, which limits its utility. So it is critical to develop methods to induce a band gap in graphene to make it a relevant semiconducting material,” he added.

In the chamber, water molecules adsorbed to the exposed side of the graphene, but not on the side facing the silicon dioxide. With the symmetry broken, the band gap of graphene did, indeed, open up, Koratkar said.

“Others have shown how to create a band gap in graphene by adsorbing different gasses to its surface, but this is the first time it has been done with water,” he said.

“The advantage of water adsorption, compared to gasses, is that it is inexpensive, nontoxic, and much easier to control in a chip application. For example, with advances in micro-packaging technologies it is relatively straightforward to construct a small enclosure around certain parts or the entirety of a computer chip in which it would be quite easy to control the level of humidity.”

The study was published this week by the journal Small. (ANI)