Sara Rothwell

Wide-Gap Semiconducting Graphene from Nitrogen-Seeded SiC

All carbon electronics based on graphene have been an elusive goal. For more than a decade, the inability to produce significant band-gaps in this material has prevented the development of graphene electronics. We demonstrate a new approach to produce semiconducting graphene that uses a submonolayer concentration of nitrogen on SiC sufficient to pin epitaxial graphene to the SiC interface as it grows. The resulting buckled graphene opens a band gap greater than 0.7 eV in the otherwise continuous metallic graphene sheet.

Evidence for bandgap opening in buckled epitaxial graphene from ultrafast time-resolved terahertz spectroscopy

Using ultrafast time-resolved THz spectroscopy, we observe two-orders-of-magnitude increase in the relaxation rate in semiconducting epitaxial graphene relative to pristine epitaxial graphene, attributed to enhancement of the optical-phonon-mediated carrier cooling and recombination over a wide range of electron temperatures.