A research group led by Dr. Takashi Tsuchiya, Dr. Kazuya Terabe, and Dr. Masakazu Aono of the International Center for Materials Nanoarchitectonics (MANA) at Japan’s National Institute for Materials Science (NIMS) has succeeded in in situ bandgap tuning of graphene oxide. This advance will be a key step toward developing high-performance nanoscale devices using extremely thin graphene oxide membranes.
Graphene is expected to be a "post-silicon" material used for making next-generation nanoscale electronic devices and circuits. However, it is a carbon material, which means it has metal conductivity but lacks a bandgap. This property has been an obstacle to constructing electronic devices with this material. Although creating and tuning a bandgap in situ using external voltage has been proposed, this approach is volatile in that the tuned bandgap is lost when the supply of external voltage is stopped.
The research group at NIMS developed a method for creating a bandgap by changing the bonding state of carbon atoms that compose graphene through reversible absorption and desorption of oxygen atoms on the graphene, and tuning the bandgap in situ. This method enables bandgap tuning in a non-volatile manner; the tuned bandgap continues to exist even when voltage supply is stopped. In order to control absorption and desorption of oxygen atoms on the graphene, the group used solid electrolytes in which hydrogen ions can move, thereby causing electrochemical reactions between oxygen atoms, which are chemically bonded to the graphene, and hydrogen ions.
This bandgap tuning method will be a key step toward developing non-volatile switching devices and other high-performance nanoelectronics devices using graphene. It will also be available as an effective tool to search and control properties of diamond as well as new carbon materials including carbon nanotubes and fullerenes.