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.