Researchers have demonstrated that bilayer graphene can act as both a superconductor and an insulator, a property that could revolutionize transistor technology. This dual function makes it possible to develop energy-efficient nanoscale transistors. An international team of researchers led by the University of Göttingen has experimentally demonstrated that electrons in naturally occurring bilayer graphene move like massless particles, in the same way that light moves.
Moving charges in natural bilayer graphene painted by the artist. Source: Lukas Kroll
In addition, they demonstrated that electric current can be "switched on and off", which opens up the possibility of developing tiny, energy-efficient transistors – like light switches in the home, but at the nanoscale. The Massachusetts Institute of Technology (MIT) in the United States and the National Institute of Materials Science (NIMS) in Japan are also involved in the study. The findings were published in the scientific journal Nature Communications.
安娜-塞勒博士。 图片来源:Christian Eckel
Characteristics and challenges of graphene
Graphene was discovered in 2004 and is made up of a single layer of carbon atoms. Graphene has a number of unusual properties, the most famous of which is its ultra-high electrical conductivity, which is due to the fact that electrons travel through this material at a high-speed, constant speed. This unique property has led scientists to dream of using graphene to create faster, more energy-efficient transistors.
The challenge is that in order to fabricate transistors, it is necessary to control the material to have a high state of insulation in addition to the high conductivity. However, in graphene, this "switching" of carrier velocity is not easy to achieve. In fact, graphene is often not insulated, which limits the potential of graphene as a transistor.
Breakthroughs have been made in graphene transistor research
The team at the University of Göttingen has now discovered that the two layers of naturally occurring bilayer graphene combine the best of both worlds: in addition to the insulating state, this structure supports electrons to move at an incredible speed like light, as if they had no mass.
The researchers found that by applying an electric field perpendicular to the material, this could be changed, making the bilayer graphene an insulator.
托马斯-韦茨教授。 资料来源:T Weitz
This property of fast-moving electrons was theoretically predicted as early as 2009, but it was only possible to discover it experimentally thanks to the materials provided by NIMS and the significant improvement in sample quality in close theoretical cooperation with MIT. Although these experiments were carried out at low temperatures – about 273° below freezing point – they showed the potential of bilayer graphene to make high-efficiency transistors.
"We've known this theory for a long time. However, now that we have done experiments, we have actually shown the dispersion of electrons in a bilayer of graphene similar to light. It's a very exciting time for the whole team," says Professor Thomas Weitz from the Department of Physics at the University of Göttingen.
Dr. Anna Seiler, a postdoctoral researcher at the University of Göttingen and first author, adds: "Our work is only a crucial first step. The next step for researchers will be to investigate whether bilayer graphene can actually improve transistors, or investigate the potential of this effect in other areas of technology. "
编译来源：ScitechDaily