Doping graphene is now easier than ever before, following the development of a new process allowing materials to be covered with the revolutionary material.
Graphene consists of a single layer of carbon atoms, arranged in a sheet. The material has unique chemical and electrical properties that could make it a revolutionary substance in fields ranging from material manufacturing to electrical engineering.
Researchers found a new way of altering the number of electrons surrounding atoms of graphene. This is the main property in atoms which determines their chemical behavior. An electrical signal was used to alter the number of electrons in the system. This advance could allow the development of graphene-based processors that could be "re-wired" electronically, without having to physically alter the device.
Silicon is currently the material of choice for computer processors, due to the fact that the number of free electrons in the material can be controlled through the introduction of impurities into the material. This process is known as doping. Semiconductors with greater numbers of electrons have a negative charge, and are known as n-type. Those lacking electrons are called p-type semiconductors, and possess a positive charge. Specific arrangements of these materials can produce transistors, integrated circuits, and computer processors.
A layer of graphene was placed on a base of periodically poled lithium niobate in a manner so that the two substances did not bound together. The base material exhibits either a positive or negative charge on its surface, and this form of the material has alternating stripes of positive and negative regions. Through the application of an electrical field, it is possible to push this lithium niobate into a desired state. This is an unstable situation, as the material attempts to gather or shed electrons, to return to neutral.
"Here we have graphene standing by, on the surface of the oxide but not binding to it. Now, if the oxide surface says, 'I wish I had more negative charge,' instead of the oxide gathering ions from the environment or gaining electrons, the graphene says 'I can hold the electrons for you, and they'll be right nearby," Andrew Rappe of the University of Pennsylvania said.
Graphene doping has been accomplished before, but the introduction of chemical impurities into the material negates some of the remarkable properties of graphene. A varying electrical field can also be used to create regions with the desired concentration of electrons, but this requires the placement of electrodes which adds to the bulk of the device.
Development of the new graphene doping technique was profiled in the journal Nature Communications.