Artist's impression of a diamond quantum sensor. The 'spotlight' represents light passing through the diamond defect and detecting the movement of electrons, which are shown as red spheres trailed by red threads that reveal their path through graphene. Image: David A. Broadway/cqc2t.org.Researchers at the University of Melbourne in Australia have become the first to image how electrons move in two-dimensional (2D) graphene, providing a boost to the development of next-generation electronics. Able to image the behavior of moving electrons in structures just one atom thick, their new technique overcomes significant limitations with existing methods for understanding electric currents in devices based on ultra-thin materials.
"Next-generation electronic devices based on ultra-thin materials, including quantum computers, will be especially vulnerable to contain minute cracks and defects that disrupt current flow," said Lloyd Hollenberg, deputy director of the Centre for Quantum Computation and Communication Technology (CQC2T) at the University of Melbourne.
A team led by Hollenberg has now used a special quantum probe based on an atomic-scale 'color center' found only in diamonds to image the flow of electric currents in graphene. This technique, which is reported in a paper in Science Advances, could be used to understand electron behavior in a variety of new technologies.
"Our method is to shine a green laser on the diamond, and see red light arising from the color center's response to an electron's magnetic field," explained lead author Jean-Philippe Tetienne from CQC2T. "By analyzing the intensity of the red light, we determine the magnetic field created by the electric current and are able to image it, and literally see the effect of material imperfections."
"The ability to see how electric currents are affected by these imperfections will allow researchers to improve the reliability and performance of existing and emerging technologies," said Hollenberg. "We are very excited by this result, which enables us to reveal the microscopic behavior of current in quantum computing devices, graphene and other 2D materials.
"Researchers at CQC2T have made great progress in atomic-scale fabrication of nanoelectronics in silicon for quantum computers. Like graphene sheets, these nanoelectronic structures are essentially one atom thick. The success of our new sensing technique means we have the potential to observe how electrons move in such structures and aid our future understanding of how quantum computers will operate."
In addition to understanding the nanoelectronics that control quantum computers, this technique could be used with 2D materials to develop next generation electronics, batteries, flexible displays and bio-chemical sensors.
"Our technique is powerful yet relatively simple to implement, which means it could be adopted by researchers and engineers from a wide range of disciplines," said Tetienne. "Using the magnetic field of moving electrons is an old idea in physics, but this is a novel implementation at the microscale with 21st century applications."
The work was a collaboration between researchers working on diamond-based quantum sensing and graphene. Their complementary expertise was crucial to overcoming technical issues that arose when combining diamond and graphene.
"No one has been able to see what is happening with electric currents in graphene before," said Nikolai Dontschuk, a graphene researcher at the University of Melbourne. "Building a device that combined graphene with the extremely sensitive nitrogen vacancy color center in diamond was challenging, but an important advantage of our approach is that it's non-invasive and robust – we don't disrupt the current by sensing it in this way."
This story is adapted from material from the University of Melbourne, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.