Berkeley Lab researchers produce ‘2-dimensional’ electronics

Mervin Zhao/Courtesy

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A team of researchers at the Lawrence Berkeley National Laboratory has developed a method for chemically producing two-dimensional transistors and circuits that may aid in the development of more advanced computers.

The research began in early 2015 and was published Monday in the journal Nature Nanotechnology. To produce its atomically thin, “two-dimensional” transistors, the team used graphene — a collection of carbon atoms in a single, one-atom-thin sheet — as a conductor for another two-dimensional substance used as a semiconductor.

After its development won the 2010 Nobel Prize in Physics, the main question became how to produce graphene, according to project researcher and campus doctoral student Mervin Zhao. Zhao said that now, however, the technology to grow graphene has been developed and the next step is how to integrate it with other two-dimensional substances to form devices.

“Our work addresses a lot of the issues with how we can complete the chemical toolbox for making two-dimensional materials (and) how we can actively use two-dimensional materials to make transistors and computers in the future,” Zhao said.

Transistors, Zhao said, are switches that function in the same way as light-switches: By applying voltage, the transistor can be turned on or off, providing the foundation for modern electronics. In this case, the transistors are composed of graphene and a transition-metal dichalcogenide, or TMDC, with the graphene measuring the voltage conducted by the TMDC.

“There’s been a lot of work in making transistors of these materials,” said Jeffrey Bokor, a campus professor of electrical engineering and computer sciences. “This work is a nice demonstration of growing (TMDC) and developing transistors.”

Zhao said the need for two-dimensional transistors has arisen to address the inadequacies of silicon as a semiconductor. He noted that silicon will always have some thickness to it, which poses a problem for developing new, smaller transistors — as called for by the rule known as Moore’s law.

Moore’s law, Bokor said, stipulates that the number of transistors used in computers should roughly double every two years. The law helps to keep up with the expected progress of the industry overall.

According to Zhao, development of two-dimensional transistors on a large scale may be difficult because of limitations imposed by current industry infrastructure and its predominant focus on silicon-based technology. Bokor, however, said progress has continued in the industry over its 50-year history despite other potential blocks, and future advancements may still be made.

“Why do they even keep doing Moore’s law? It costs lots of money — even just for research with silicon — and requires huge research and development,” Bokor said. “They follow it because there’s so much money to be made.”

Contact Trevor Greenan at [email protected] and follow him on Twitter at @trevor_greenan.

A previous version of this article incorrectly used the acronym TMCD when referring to transition-metal dichalcogenide. The acronym should instead read TMDC.