Engineering of Graphene Gives it Piezoelectric Properties

Modeling and simulation of precise doping of graphene may provide path for imparting piezoelectric properties in a range of nanomaterials

2 min read
Engineering of Graphene Gives it Piezoelectric Properties

Researchers at Stanford University are extending the capabilities of graphene by engineering piezoelectric capabilities into the material.

"The physical deformations we can create are directly proportional to the electrical field applied and this represents a fundamentally new way to control electronics at the nanoscale," says Evan Reed, head of the Materials Computation and Theory Group at Stanford and senior author of the study. "This phenomenon brings new dimension to the concept of 'straintronics' for the way the electrical field strains—or deforms—the lattice of carbon, causing it to change shape in predictable ways."

The concept of ‘straintronics’ in Graphene was demonstrated at least as far back as 2010 when Lawrence Berkeley National Laboratory research, led by Michael Crommie, professor of physics at UC Berkeley and a faculty researcher at LBNL, serendipitously discovered that when graphene was grown on platinum a strain pattern was created.

It should be noted that the Stanford research, which was published in the journal ACS Nano,  was conducted within modeling and simulation software. Nonetheless the researchers achieved their piezoelectric effect quite deliberately in the models by depositing lithium, hydrogen, potassium and fluorine atoms on one side of the graphene lattice. They expected this to generate a piezoelectric effect, but not on the scale they witnessed in the models.

“We thought the piezoelectric effect would be present, but relatively small. Yet, we were able to achieve piezoelectric levels comparable to traditional three-dimensional materials," said Reed. "It was pretty significant."

While the level of the piezoelectric effect was unexpected, the real breakthrough here may be that they were able to control the effect by depositing the atoms in specific locations within the graphene.

"We were further able to fine tune the effect by pattern doping the graphene—selectively placing atoms in specific sections and not others," said Mitchell Ong, a post-doctoral scholar in Reed's lab and first author of the paper. "We call it designer piezoelectricity because it allows us to strategically control where, when and how much the graphene is deformed by an applied electrical field with promising implications for engineering."

It should be interesting to see if anyone takes on these simulations and starts running physical experiments. If it can be duplicated in physical experiments, it could open the possibility for this kind of doping to be used on other nanomaterials that could open their use in a number of application areas, ranging from energy harvesting to chemical sensing and high-frequency acoustics.

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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