Mind the gap: Hydrogen meets Graphene
Wednesday 26 October 2011
Scientists at the Advanced Technology Institute of the University of Surrey have demonstrated a new semiconducting phase of graphene formed by the self-organisation of hydrogen atoms on its surface.
Graphene is a monolayer of carbon atoms arranged in a hexagonal lattice like a chicken wire mesh. The discovery of graphene resulted in the award of the 2010 Nobel Prize in Physics, for its unique and fundamental properties with many practical applications envisaged, such as large-area transparent conductors, sensors, solar cells, supercapacitors and transistors.
Graphene in its pure state is a semi-metal, however, the adsorption of hydrogen can result in semiconducting behaviour resulting in the formation of an energy gap. This enables the prospects of new types of electronic device not previously considered with pure graphene.
At the University of Surrey, researchers have studied the controlled adsorption of hydrogen onto a monolayer graphene surface using our ultra-high vacuum scanning tunnelling microscope. At high levels of hydrogen adsorption, we have shown self-assembly and ordering of the hydrogen atoms forming a structure akin to a C4H polymer.
The analysis also shows an upper limit to the amount of hydrogen which can be stored by chemisorption under the applied conditions. Calculation of the electronic bandstructure of this new material reveals a wide-gap semiconductor with potential applications for UV photonics.
Professor Ravi Silva, a co-author of the work indicated that: “I am very pleased our work on the fundamental studies of graphene surfaces is featured in Advanced Materials and made the front cover of the journal. This research, which has been carried out over the last year in collaboration with ten laboratories distributed around the world, shows the ability of science to overcome national boundaries and distance when it comes to performing good science.
"I hope the discovery of a new stable phase of C4H with a wide optical bandgap will spur more effort into the formation of semiconducting graphene and its utilisation in carbon electronics and photonics. Carbon electronics is strong in the UK with many fundamental discoveries underpinning the research in the field.”
The work is featured in the 18 October 2011 edition of Advanced Materials.
