A method of path definition to allow wide applications for a graphene

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Physicist Fang Zhao with figures from her article. Credit: Fang Zhao

Super strong and single atom thick, graphene holds promise as a nanomaterial for everything from microelectronics to clean energy storage. But the lack of a property has limited its use. Today, researchers at Princeton University and the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have overcome this problem by using low-temperature plasma, creating a new technique that opens up the door to a wide range of industrial and scientific applications for the promising nanomaterial.

Stronger than steel

Graphene, which is harder than diamond and stronger than steel, could be the foundation for next-generation technologies. But the absence of a property called bandgap in the pencil graphite that makes up graphene limits its ability to function as a semiconductor, the material at the heart of microelectronic devices. Semiconductors both insulate and conduct electric current, but although graphene is an excellent conductor, it cannot serve as an insulator without a bandgap.

“People are using silicon which has a bandgap for semiconductors,” said Fang Zhao, lead author of the newspaper. Carbon which describes the new process. “The opening of a large band gap on graphene has given rise to intense studies of the use of semiconductors,” said Zhao, a physicist at the Fermi National Accelerator Laboratory (Fermilab) who wrote the article. while he was a post-doctoral researcher at Princeton.

The dilemma has led scientists around the world to explore ways to produce a bandgap in graphene to expand its potential applications. One popular method has been to chemically modify the surface of graphene with hydrogen, a process called “hydrogenation”. But the conventional way of proceeding produces irreversible etching and sputtering which can seriously damage the surface of graphene, known as a 2D material due to its ultra-thin nature, within seconds or minutes.

Scientists at Princeton and PPPL have now shown that a new method of graphene hydrogenation can safely open the door to many microelectronic applications. The method marks a new way to produce a hydrogen plasma that dramatically expands the hydrogen coverage in 2D material. “This process creates much longer hydrogen treatments due to its low damage to graphene,” Zhao said.

Plasma, the hot, charged state of matter composed of free electrons and atomic nuclei, represents 99% of the visible universe. The low-temperature hydrogen plasma developed by PPPL to hydrogenate graphene contrasts with the million-degree fusion plasmas that have long been the hallmark of PPPL research, which aims to develop safe, clean and abundant fusion energy. to generate electricity.

Ptolemy’s spin-off

The new method stems from an experiment called Ptolemy, an academic project that Princeton physicist Chris Tully developed with help from Zhao. This project uses the decay of tritium, the radioactive isotope of hydrogen, in an attempt to capture relic neutrinos that emerged just seconds after the Big Bang that created the universe. Such relics could shed new light on the Big Bang, according to the Ptolemy project.

To improve the decay detection rate, Tully turned to PPPL physicist Yevgeny Raitses, who leads low-temperature plasma research at PPPL. “PPPL’s ​​desire to join forces and bring 2D processing properties to materials is inspiring,” said Tully. “Breaking the world record for graphene hydrogenation efficiency is a tribute to the unique capabilities of PPPL.”

Raitses and his colleagues developed a method to extend the hydrogen blanket in graphene that harbors the decay of tritium. The process greatly increases future applications of graphene. “This spin-off of Ptolemy can now be used for microelectronics, QIS [quantum information science] and other applications, ”said Raitses. “The method can also be applied to other 2D materials.

The spin-off combines electric and magnetic fields to produce a hydrogen plasma that provides a lot of hydrogen with little damage to the graphene. This gentle and well-controlled method is itself a spinoff of research that Raitses developed while studying Hall-effect thrusters, the plasma engines of spacecraft propulsion. The technique hydrogenated graphene for up to 30 minutes in PPPL experiments, dramatically increasing hydrogen coverage and opening a bandgap that turns graphene into a semiconductor material.

All this, says the Carbon paper, creates an attractive method for making 2D materials “exciting and promising”. [sources] for wide applications. “

Princeton physicists Chris Tully and Andi Tan, as well as chemist Xiaofang Yang from Princeton’s Department of Chemical and Biological Engineering also collaborated on this article. Support for this work comes from the DOE Office of Science (FES) and the Air Force Office of Scientific Research.


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More information:
Fang Zhao et al, High hydrogen coverage on graphene via low temperature plasma with applied magnetic field, Carbon (2021). DOI: 10.1016 / j.carbon.2021.02.084

Provided by Princeton Plasma Physics Laboratory

Quote: A path definition method to allow broad applications for a graphene (2021, October 19) retrieved October 19, 2021 from https://phys.org/news/2021-10-path-setting-method-enable -vast-applications. html

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