Graphene nanoribbons can now easily be grown in laboratories, which could herald a new generation of faster electronic devices. The ribbons are grown on a base of germanium, and the fine fibers automatically align with each other, forming into a configuration known as an armchair shape.
Germanium is a metaloid chemical element, number 32 on the periodic table. Chemically, the substance acts much like silicon and tin.
Graphene consists of carbon atoms, arranged in a single layer, usually in a sheet. This material has remarkable tensile and electronic properties. Many researchers believe that if the material could be produced in reasonable quantities, it could revolutionize the manufacture of semiconductors, leading to far more efficient computer processors.
However, manufacturing the material into the form of fine nanotubes has remained a time-consuming process, unable to create enough fibers for use. These nanofibers must be less than 0.0000004 inches across, just over half the width of a human hair.
Previously, investigators seeking to create graphene nanofibers usually slice ribbons from a sheet. However, this technique leaves ribbons with rough edges. Growing ribbons of graphene, which produces fibers with smooth edges, required a metal substrate, generating just short segments of the fibers.
"Graphene nanoribbons that can be grown directly on the surface of a semiconductor like germanium are more compatible with planar processing that's used in the semiconductor industry, and so there would be less of a barrier to integrating these really excellent materials into electronics in the future," Michael Arnold of the University of Wisconsin – Madison said.
Researchers grew the ultra-thin ribbons on a bed of germanium, producing fibers with smooth edges. The process begins with the application of methane onto the germanium substrate. This then decays into a range of forms of hydrocarbons, which in turn react with each other, creating graphene. The team discovered during experimentation that at low rates of methane injection, this graphene naturally formed into nanoribbons.
"The widths can be very, very narrow and the lengths of the ribbons can be very long, so all the desirable features we want in graphene nanoribbons are happening automatically with this technique," Arnold stated in a university press release.
The new technique for growing these fine threads of graphene can easily be scaled up to industrial levels of production, researchers tell the press.
Future development of graphene nanoribbons could lead to photonic devices capable of manipulating light. The nanoribbons may also be used to develop a new generation of devices designed to recognize specific biological and chemical compounds.
Development of the new method of growing graphene nanoribbons was detailed in the journal Nature Communications.