Epitaxial Graphene Buffer Layer Electronic Devices*

The first graphene layer grown by thermal decomposition of the (0001) surface of hexagonal silicon
carbide (buffer layer) is a semiconducting form of graphene. While the nature of the buffer layer has
been investigated in many surface science studies, the semiconducting transport properties of the
buffer layer have yet to be measured and explained. We produced top gated buffer layer devices and
studied their behavior in the temperature range 2K-400K. The channel conduction shows thermally
and electrically activated transport involving charge carriers that are trapped in the 6√3X6√3 periodic
potential of the buffer layer. We also report on the doping processes through the adsorption of several
chemical species on the buffer layer.