New technique for stopping electrons could enable graphene-based switching mechanisms, paving the way for its use in computing and other applications
Wonder-material graphene is a promising candidate for electronic devices, thanks to its excellent conductivity. However, there is a catch: electrons move through the material so well that they can’t be stopped. This precludes graphene’s use as a transistor, which must be capable of switching on and off.
Yet a new study from staff at Rutgers University-New Brunswick suggests a method of “taming” these excitable electrons, potentially enabling the material’s use as an ultra-fast transporter of electrons with a low loss of energy.
Their study, published online in Nature Nanotechnology, suggest it may become possible to create a graphene nano-scale transistor. The team managed controlled the electrons by sending voltage through a high-tech microscope with an extremely sharp tip, also the size of one atom. They created what resembles an optical system by sending voltage through a scanning tunnelling microscope, which offers 3-D views of surfaces at the atomic scale.
The microscope’s sharp tip creates a force field that traps electrons in graphene or modifies their trajectories, similar to the effect a lens has on light rays. Electrons can easily be trapped and released, providing an efficient on-off switching mechanism, according to Board of Governors professor in Rutgers’ Department of Physics and Astronomy in the School of Arts and Sciences Eva Y. Andrei, also the study’s senior author.
“You can trap electrons without making holes in the graphene,” she said. “If you change the voltage, you can release the electrons. So you can catch them and let them go at will… 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 Andrei, the next step would be to scale up by putting extremely thin wires, called nanowires, on top of graphene and controlling the electrons with voltages.
The study’s co-lead authors are Yuhang Jiang and Jinhai Mao, Rutgers postdoctoral fellows, and a graduate student at Universiteit Antwerpen in Belgium. The other Rutgers co-author is Guohong Li, a research associate.