Atoms use tunnels to escape graphene cover

November 1, 2018, Leiden University
Credit: Leiden Institute of Physics

Graphene has held great potential for practical applications since it was first isolated in 2004. But we still don't use it in our large-scale technology, because we have no way of producing graphene on an industrial scale. Physicists from Leiden University have now visualized for the first time how atoms behave in between graphene and a substrate. This insight could be instrumental for future implementations of industrial graphene production. Their results have been published in Physical Review Materials.

In 2004, scientists isolated a single layer of carbon atoms from a block of graphite. Graphene layers could enable high-speed transistors, inexpensive electrical cars and delicate sensors. Fast-forward to 2018, and graphene there are still few large-scale graphene applications. The problem is that researchers haven't figured out a way to produce graphene in high quality on the right substrate on an industrial scale.

Though scientists do have an idea for large-scale production: Heat silicon carbide to almost 2,000 degrees C, and a graphene layer grows on its surface. However, researchers need to make sure that the desired properties of the graphene are not disturbed by the substrate. Inserting hydrogen atoms in between the graphene and silicon carbide isolates the graphene and leaves it intact as a single-layer material. Physicist Sense Jan van der Molen and his research group at Leiden University have now visualized for the first time how those atoms behave underneath the graphene.

The researchers, including postdoc Johannes Jobst and PhD candidate Tobias de Jong, used their low-energy electron microscope (LEEM) to study what happens to hydrogen atoms sandwiched between graphene and silicon carbide. They spotted lines where the graphene layer is strained. The hydrogen atoms use the lines as tunnels where they can escape more easily, whereas they stay put much longer under the graphene's smooth regions between these lines. "The reversed process is widely used in research to decouple the graphene from the substrate," says Jobst. "But it was not clear how the hydrogen moves at the interface. We could show that hydrogen gas can be blown into those tunnels so that it will spread quickly underneath the graphene layer in the form of individual atoms."

LEEM image of a graphene layer grown on a silicon carbide substrate. A red color indicates the presence of hydrogen atoms sandwiched between graphene and silicon carbide. The dark lines indicate strained regions in the graphene. The surrounding white areas show where the hydrogen atoms already left the interface. This shows that the lines act as tunnels where the hydrogen flows away faster. Credit: Leiden Institute of Physics

Explore further: Researchers have fabricated two types of trilayer graphene with different electrical properties

More information: T. A. de Jong et al. Intrinsic stacking domains in graphene on silicon carbide: A pathway for intercalation, Physical Review Materials (2018). DOI: 10.1103/PhysRevMaterials.2.104005

Related Stories

Scientists move graphene closer to transistor applications

August 29, 2017

Scientists at the U.S. Department of Energy's Ames Laboratory were able to successfully manipulate the electronic structure of graphene, which may enable the fabrication of graphene transistors— faster and more reliable ...

New insights on graphene

December 21, 2017

Graphene floating on water does not repel water, as many researchers believe, but rather attracts it. This has been demonstrated by chemists Liubov Belyaeva and Pauline van Deursen and their supervisor Grégory F. Schneider. ...

Effective graphene doping depends on substrate material

March 29, 2016

Juelich physicists have discovered unexpected effects in doped graphene - i.e. graphene that is mixed with foreign atoms. They investigated samples of the carbon compound enriched with the foreign atom nitrogen on various ...

New chemical method could revolutionize graphene

June 15, 2017

University of Illinois at Chicago scientists have discovered a new chemical method that enables graphene to be incorporated into a wide range of applications while maintaining its ultra-fast electronics.

Graphene on silicon carbide can store energy

May 23, 2017

By introducing defects into the perfect surface of graphene on silicon carbide, researchers at Linköping University in Sweden have increased the capacity of the material to store electrical charge. This result, which has ...

Recommended for you

Matter waves and quantum splinters

March 25, 2019

Physicists in the United States, Austria and Brazil have shown that shaking ultracold Bose-Einstein condensates (BECs) can cause them to either divide into uniform segments or shatter into unpredictable splinters, depending ...

Study suggests trees are crucial to the future of our cities

March 25, 2019

The shade of a single tree can provide welcome relief from the hot summer sun. But when that single tree is part of a small forest, it creates a profound cooling effect. According to a study published today in the Proceedings ...

How tree diversity regulates invading forest pests

March 25, 2019

A national-scale study of U.S. forests found strong relationships between the diversity of native tree species and the number of nonnative pests that pose economic and ecological threats to the nation's forests.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.