Making P-N Junctions in Graphene
In the heart of our computers, where the silicon transistors lie, are junctions between positively and negatively charged regions. Typically these regions are created by doping one material, like silicon, with atoms of another. However, replicating the process with the potential silicon replacer, graphene, risks impairing graphene's performance, but researchers at the Georgia Institute of Technology have found a way around that.
Graphene is a single atom thick sheet of carbon that can be manufactured by having the carbon atoms fall onto a substrate and form the structure of graphene. The properties of the substrate can greatly affect the properties of the graphene, and this is what the researchers are tapping into. By carefully designing the substrate, a self-assembled monolayer, the researchers can donate or withdraw electrons from the graphene, to create p-n junctions. Because this does not disrupt the structure of the graphene, it does not impair its electron mobility, unlike typical doping methods which replace one atom for another.
While the ability to create p-n junctions in graphene is important, another benefit of this technique is that it does not require the graphene be transferred from one substrate to another. The graphene can be grown directly on the monolayer, which will simplify any manufacturing efforts in the future.