MMaterialsgateNEWS 2016/08/03

Graphene: Swapping substrates improves edges of graphene nanoribbons

Using inert boron nitride instead of silica creates precise zigzag edges in monolayer graphene

It is now feasible to make a prized material for spintronic devices and semiconductors -- monolayer graphene nanoribbons with zigzag edges.

Miniscule ribbons of graphene are highly sought-after building blocks for semiconductor devices because of their predicted electronic properties. But making these nanostructures has remained a challenge. Now, a team of researchers from China and Japan have devised a new method to make the structures in the lab. Their findings appear in the current issue of Applied Physics Letters, from AIP Publishing.

"Many studies have predicted the properties of graphene nanoribbons with zigzag edges," said Guangyu Zhang, senior author on the study. "But in experiments it's very hard to actually make this material."

Previously, researchers have tried to make graphene nanoribbons by placing sheets of graphene over a layer of silica and using atomic hydrogen to etch strips with zigzag edges, a process known as anisotropic etching. These edges are crucial to modulate the nanoribbon's properties.

But this method only worked well to make ribbons that had two or more graphene layers. Irregularities in silica created by electronic peaks and valleys roughen its surface, so creating precise zigzag edges on graphene monolayers was a challenge. Zhang and his colleagues from the Chinese Academy of Sciences, Beijing Key Laboratory for Nanomaterials and Nanodevices, and the Collaborative Innovation Center of Quantum Matter teamed up with Japanese collaborators from the National Institute for Materials Science to solve the problem.

They replaced the underlying silica with boron nitride, a crystalline material that's chemically sluggish and has a smooth surface devoid of electronic bumps and pits. By using this substrate and the anisotropic etching technique, the group successfully made graphene nanoribbons that were only one-layer thick, and had well-defined zigzag edges.

"This is the first time we have ever seen that graphene on a boron nitride surface can be fabricated in such a controllable way," Zhang explained.

The zigzag-edged nanoribbons showed high electron mobility in the range of 2000 cm2/Vs even at widths of less than 10nm -- the highest value ever reported for these structures -- and created clean, narrow energy band gaps, which makes them promising materials for spintronic and nano-electronic devices.

"When you decrease the width of the nanoribbons, the mobility decreases drastically because of edge defects," said Zhang. "Using standard lithography fabrication techniques, studies have seen mobility of 100 cm2/Vs or even lower, but our material still exceeds 2000 cm2/Vs even at the sub-10 nanometer scale, demonstrating that these nanoribbons are of very high quality."

In future studies, extending this method to other kinds of substrates could enable the quick large scale processing of monolayers of graphene to make high-quality nanoribbons with zigzag edges.

Source: American Institute of Physics – 01.08.2016.

The article, "Patterning monolayer graphene with zigzag edges on hexagonal boron nitride by anisotropic etching," is authored by Guole Wang, Shuang Wu, Tingting Zhang, Peng Chen, Xiaobo Lu, Shuopei Wang, Duoming Wang, Kenji Watanabe, Takashi Taniguchi, Dongxia Shi, Rong Yang and Guangyu Zhang. The article will appear in Applied Physics Letters August 1, 2016 (DOI: 10.1063/1.4959963). After that date, it can be accessed at

Investigated and edited by:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
Büro für Material- und Technologieberatung
The investigation and editing of this document was performed with best care and attention.
For the accuracy, validity, availability and applicability of the given information, we take no liability.
Please discuss the suitability concerning your specific application with the experts of the named company or organization.

You want additional material or technology investigations concerning this subject?

Materialsgate is leading in material consulting and material investigation.
Feel free to use our established consulting services

MMore on this topic

Researchers from Moscow Institute of Physics and Technology (MIPT), Skolkovo Institute of Science and Technology (Skoltech), the Technological Institute for Superhard and Novel Carbon Materials (TISNCM), the National University of Science and Technology MISiS (Russia), and Rice University (USA) used computer simulations to find how thin a slab of salt has to be in order for it to break up into graphene-like layers.

Based on the computer simulation, they derived the equation for the number of layers in a crystal that will produce ultrathin films with applications in nanoelectronics. Their findings were in The Journal of Physical Chemistry Letters (which has an impact factor of 8.54). From 3D to 2D Unique monoatomic thickness of graphene makes it an attractive and useful material. Its crystal lattice resembles a honeycombs, as the bonds between the constituent atoms form regular hexagons. Graphene is a single layer of a three-dimensional graphite crystal and its properties (as well as properties of any 2D crystal) are radically different from its 3D counterpart. Since the discovery of graphene, a large... more read more

New nanomaterial conducts differently at right angles

Graphene, a two-dimensional wonder-material composed of a single layer of carbon atoms linked in a hexagonal chicken-wire pattern, has attracted intense interest for its phenomenal ability to conduct electricity. Now University of Illinois at Chicago researchers have used rod-shaped bacteria - precisely aligned in an electric field, then vacuum-shrunk under a graphene sheet - to introduce nanoscale ripples in the material, causing it to conduct electrons differently in perpendicular directions. The resulting material, sort of a graphene nano-corduroy, can be applied to a silicon chip and may add to graphene's almost limitless potential in electronics and nanotechnology. The finding... more read more

Researchers from the University of Illinois at Urbana-Champaign have demonstrated doping-induced tunable wetting and adhesion of graphene, revealing new and unique opportunities for advanced coating materials and transducers.

"Our study suggests for the first time that the doping-induced modulation of the charge carrier density in graphene influences its wettability and adhesion," explained SungWoo Nam, an assistant professor in the Department of Mechanical Science and Engineering at Illinois. "This work investigates this new doping-induced tunable wetting phenomena which is unique to graphene and potentially other 2D materials in complementary theoretical and experimental investigations." Graphene, being optically transparent and possessing superior electrical and mechanical properties, can revolutionize the fields of surface coatings and electrowetting displays, according to the researchers... more read more

MaterialsgateNEWSLETTER

Partner of the Week

Search in MaterialsgateNEWS

Books and products

MaterialsgateFAIR:
LET YOURSELF BE INSPIRED