Graphene Makes Copper Nanowires Useful for Flexible Displays

Coating copper nanowires with graphene lowers their resistance and and heat buildup

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Graphene Makes Copper Nanowires Useful for Flexible Displays
Illustration: Purdue University

What happens when you coat copper nanowires with graphene? According to research out of Purdue University, you lower the resistance and susceptibility to heating of the copper wires. This could allow copper nanowires to be used in a wider range of electronics.

“Highly conductive copper nanowires are essential for efficient data transfer and heat conduction in many applications like high-performance semiconductor chips and transparent displays,” said doctoral student Ruchit Mehta in a press release. She has been working as part of a team led by Zhihong Chen, an associate professor of electrical and computer engineering at Purdue University.

In research published in the journal Nano Letters,  the Purdue team developed a method for encapsulating the wires with graphene. Compared to uncoated wires, the encapsulated wires can transmit data 15 percent faster while reducing the peak temperature by 27 percent.

“This is compelling evidence for improved speed and thermal management by adapting the copper-graphene hybrid technology in future silicon chips and flexible electronic applications,” Mehta added in the release.

As we learned earlier this week, graphene is effective at dissipating heat in part because heat propagates as a wave in it, which is quite different from the all-direction-vibration of atoms as seen in three-dimensional materials.

By combining graphene with nanowires, it could become possible to address some of heat issues that arise from the high packing density of today’s electronic components in chips.

As the wires on these chips become smaller to accommodate the packing density, both their electrical and thermal conductivity are compromised due to oxidation. With the graphene coating the copper wires are resistant to oxidation, maintaining low resistance and dissipating heat more effectively. In particular, the researchers believe that the hybrid wires could make the copper nanowires applicable to transparent flexible displays, where previously they were a poor fit because of oxidation problems.

“If the surface is covered with oxide then a lot of the electrical and thermal conductive properties of copper are lost,” Mehta said. “This is very important because you want as much current as possible going through these wires to increase speed, but they cannot take too much current because they will melt. But if the copper has good electrical and thermal conductivity you can push more current through it.”

Of course, others have looked at the potential of coating nanowires with graphene, but the process proved too daunting because it required chemical vapor deposition (CVD), which operates at 1000 degrees Celsius, which can ruin both copper thin films and small-dimension wires.

The breakthrough achieved by the Purdue team was to use a plasma-enhanced CVD that can be run at 650 degrees Celsius, keeping the small wires intact.

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