By Will Soutter
Graphene is a one-atom-thick carbon material that demonstrates exotic properties suitable for the development of advanced electronic devices. However, to develop these graphene-based electronic devices, it is necessary to create junctions that link the nanomaterial to the ‘external world’ via at least two metal wires.
A graphene ribbon that has two metal contacts is dubbed as a ‘two-terminal junction.’ Salvador Barraza-Lopez, Assistant Professor of Physics at University of Arkansas, and M.Y. Chou of the Academia Sinica in Taiepi, Taiwan, and Georgia Institute of Technology (Georgia Tech) and Markus Kindermann of Georgia Tech have provided new insights that elucidate the impact of these graphene-metal interfaces on electron movement via two-terminal junctions.
Existing theories describing graphene devices propose that the contacts that shift electricity from point to point will be made of ‘doped’ graphene. This means the contacts possess a huge amount of electronic charge like actual metals. Nevertheless, contacts in real devices are composed of transition metals and they will create bonds with graphene.
Barraza-Lopez explained that the formation of covalent bonds obliterate graphene’s exotic electronic properties. Hence, the researchers believed that it is essential to measure electron movement going beyond the theory that the contacts are doped graphene by themselves.
The researchers explored electron movement via graphene junctions with titanium. They took actual junctions’ material properties into account and contrasted their results with several existing basic models. They used quantum mechanics principles and advanced computational facilities to perform their calculations.
Under quantum mechanics, the electrons at graphene-metal junctions act more like a beam of light when it is illuminated on a crystal, causing part of the light to scatter and part of it to pass through. For graphene junctions, the material’s electronic transparency shows the number of electrons on one contact moved to the other metal contact.
According to the researchers, the study findings provide insights into graphene junctions’ complex behavior, thus opening the door for realistic design of advanced electronic devices.