The University of Wisconsin announced last week that researchers have discovered a way to grow graphene nanoribbons with desirable semiconducting properties directly on a germanium semiconductor wafer. This could allow manufacturers to use ultra-narrow graphene nanoribbons in hybrid integrated circuits, which would enhance the performance of future electronic devices.
Before this study, scientists had struggled to turn graphene into nanoribbons using lithographic techniques. In order to take advantage of graphene’s electric properties in a semiconductor applications, the researchers had to make the graphene nanoribbons only 10 nanometers wide. The nanoribbons also needed to have smooth, well-defined “armchair” edges in which the carbon-carbon bonds are parallel to the length of the ribbon.
The researchers overcame these obstacles by creating a “bottom-up” technique that can grow perfectly sized nanoribbons directly on germanium wafers through a process called chemical vapor deposition. In this method, the scientists use methane to absorb the germanium surface. The methane then decomposes to form hydrocarbons that react with each other on the surface to form graphene.
“What we’ve discovered is that when graphene grows on germanium, it naturally forms nanoribbons with these very smooth, armchair edges,” explains University of Wisconsin Prof. Michael Arnold, one of the authors of the study that led to the discovery. “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.”
In addition to traditional electronics, the technology could also have specific uses in industrial and military applications, such as sensors that detect specific chemical and biological species and photonic devices that manipulate light.
For more information, read the full study, Direct oriented growth of armchair graphene nanoribbons on germanium, online.