Looking at the Edge of Graphene
Graphene is an amazing material with its special mechanical, electrical, and optical properties, making it of key interest to many. The hope is to one day use it in a variety of devices such as advanced sensors and higher speed and efficiency electronics. Now researchers at the National Physical Laboratory have discovered that the edge of graphene has some interesting properties that could influence some future applications.
One of the main reasons graphene is studied so much is that electrons can move along it at great speed and with little resistance. Such electron conduction would be very useful for many devices, but the NPL researchers have discovered that the edge of graphene conducts differently. While the bulk of the plane conducts electrons, the edges instead conduct the positively charged holes left behind by excited electrons. Effectively this makes the interior of a graphene sheet n-doped with the edge p-doped, and while both can conduct electricity, the differences are important for designing devices.
With side-gates the researchers were able to tune the conduction of the edges without affecting the center. The researchers also discovered that the differences in conduction were most pronounced after the graphene had been cleaned, but faded over time, suggesting it is the result of defects that were filled by airborne molecules.
Source: National Physical Laboratory