Gaining control over wild electrons could allow for new graphene-based devices
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Researchers have developed a technique for controlling the motion of electrons in graphene. This could make the development of graphene nanoscale transistors possible.
Graphene – an atom-thick layer of carbon atoms in a hexagonal lattice – has exceptional properties. This has resulted in graphene being named a ‘wonder material’. Its unparalleled strength and other properties could result in applications in manufacturing, medicine and many other sectors.
For instance, its extremely high electrical conductivity has allowed for the creation of new electronic devices and materials, including supercapacitors and ultra-low resistivity wires, and could eventually lead to the development of flexible, transparent devices and new printable circuits.
Despite the excitement surrounding the possibilities of graphene, the material has a drawback. When electrons pass through graphene, they move in straight lines through graphene, their velocities unchanged, and the electrons unstoppable.
“If they hit a barrier, they can’t turn back, so they have to go through it,” said Professor Eva Andrei, a physicist at Rutgers University-New Brunswick, and senior author of the study. “People have been looking at how to control or tame these electrons.”
Professor Andrei and her colleagues have developed a technique for controlling these electrons, which could allow for the development of systems using ultra-fast transport of electrons with minimal energy loss.
They achieved this by sending a voltage through a highly precise microscope – a scanning tunneling microscope – which has a tip the size of a single atom. The tip of the microscope creates a field in the graphene that traps electrons or changes their motion, without having to create holes in the graphene.
As electrons can be trapped and released with a simple change of voltage, this technique could provide an on-off switching mechanism for graphene-based devices.
“This shows we can electrically control the electrons in graphene,” said Professor Andrei. “In the past we couldn’t do it. This is the reason people thought that one could not make devices like transistors that require switching with graphene, because their electrons run wild.”
According to the researchers, harnessing greater control over electrons in graphene could allow for the development of novel electronic devices, such as graphene nanoscale transistors. The next step in the team’s work, Professor Andrei said, is to scale up this technique by laying nanowires atop graphene, and using these to control the flow of electrons.