Graphene nanoribbon under the microscope.
(Image: University of Basel)
(August 27, 2015) Physicists at the University of Basel succeed in synthesizing boron-doped graphene nanoribbons and characterizing their structural, electronic and chemical properties. The modified material could potentially be used as a sensor for the ecologically damaging nitrogen oxides, scientists report in the latest issue of Nature Communications.
Graphene is one of the most promising materials for improving electronic devices. The two-dimensional carbon sheet exhibits high electron mobility and accordingly has excellent conductivity. Other than usual semiconductors, the material lacks the so-called band gap, an energy range in a solid where no electron states can exist. Therefore, it avoids a situation in which the device is electronically switched off. However, in order to fabricate efficient electronic switches from graphene, it is necessary that the material can be switched ”on” and ”off”.
The solution to this problem lies in trimming the graphene sheet to a ribbon-like shape, named graphene nanoribbon (GNR). Thereby it can be altered to have a band gap whose value is dependent on the width of the shape.
Synthesis on Gold Surface
To tune the band gap in order for the graphene nanoribbons to act like a well-established silicon semiconductor, the ribbons are being doped. To that end, the researchers intentionally introduce impurities into pure material for the purpose of modulating its electrical properties. While nitrogen doping has been realized, boron-doping has remained unexplored. Subsequently, the electronic and chemical properties have stayed unclear thus far.