Introducing Novel Substrates Enhances Edges of Graphene Nanoribbons

It is now possible to prepare a spectacular material for spintronic gadgets and semiconductors – monolayer graphene nanoribbons with criss-cross edges. Miniscule patterns of graphene are exceedingly sought-after linking blocks for semi-conductor gadgets because of their expected electrical properties. But preparing such nanostructures is still a challenge. Now, a group of scientists from Japan and China has devised a novel technique to prepare the structures in the laboratory.

According to their research work, “Numerous experiments have expected the characteristics of graphene nanoribbons with curvy edges,” says Guangyu Zhang, the senior lecturer of the experiment. “But in researches, it is extremely troubling to practically craft this material.”

Traditionally, scientists have put in efforts to prepare graphene nanoribbons by incorporating sheets of graphene above a fine layer of silica with the use of atomic hydrogen to carve strips with curvy boundaries, a procedure known as anisotropic etching. Such edges are critical to modify the nanoribbon’s characteristics.

But such technique only functioned well to prepare ribbons that possess two or more numbers of graphene layers. Abnormalities in silica generated by electrical valleys and peaks roughen its layers, so preparing accurate criss-cross boundaries on graphene monolayers was a limitation. Zhang and his team members from the Academy of Sciences in China, Collaborative Innovation Centre of Quantum Matter and Bejing Key Laboratory for Nanomaterials gathered together with collaborators from Japan from the National Institute for Materials Science to find a solution to various problems.

They substituted the primary silica with boron nitride, a crystalline substance that is chemically sluggish and has a smooth surface without electrical pits and bumps. By utilizing such substrate and the anisotropic etching method, the team potentially created graphene nanoribbons that were only single-layer thick and had well delineated criss-cross edges.

“It is the very first time we have ever witnessed that graphene on the surface of boron nitride can be structured in such a regulated way,” Zang explained.

The criss-cross boundaries nano-ribbons revealed high electron movement in the range of 2000 cm2/Vs even at dimensions of less than 10nm, which is the biggest value ever noted for these structures – and prepared narrow, clean energy band gaps that make them lucrative materials for spintronics and nano-electronic gadgets.

“When you reduce the dimension of the nanoribbons, the movement decreases to a great extent because of the defects in the edges,” says Zhang. “Utilizing standard lithography structuring techniques, reports have witnessed the movement of 100 cm2/Vs of even less, but our substance still surpasses 2000 ccm2/Vs even at the nanometre scale, illustrating that such nanoribbons are of exceedingly high quality.”

In future experiments, extending this technique to other types of substrates could allow the rapid, large-scale treating of monolayers of graphene to prepare excellent quality nanoribbons with criss-cross boundaries. While these ribbons of graphene are exceedingly sought-after structuring blocks for semiconductor gadgets because of their fine electrical properties, it is still a big challenge to create nanostructures with fine properties. It is now to be seen the overall success rate of this newly introduced technique.