J. D. Buron1, F. Pizzocchero1, M. Hilke2, E. Whiteway2, P. Jepsen3, P. Bøggild1
1DTU Nanotech, Technical University of Denmark, 2Department of Physics, McGill University, 3DTU Photonics, Technical University of Denmark 

Using ultra-broadband terahertz time-domain spectroscopy (THz-TDS), we report on the first definitive observation of Non-drude equilibrium charge carrier dynamics in a large-area graphene film grown by chemical vapour deposition on copper foil. Sheet conductance spectra for CVD graphene films grown under 2 different sets of growth conditions are obtained by ultra-broadband THz-TDS based on terahertz air wave photonics as well as conventional THz-TDS based on photoconductive antennas, spanning the entire frequency range from 0.1 to 15 THz associated with intraband optical conductance. In the case of CVD graphene grown under optimized conditions, a Drude intraband conductance spectrum is observed, while a conductance spectrum showing distinct non-Drude characteristics are observed in the case of less optimized CVD graphene growth. The observations are interpreted in the framework of the Drude-Smith model for restricted nanoscopic carrier movement caused by preferential carrier backscattering on extended electronic barriers. 

Jonas Buron is currently a post-doctoral fellow in the Nanocarbon group at DTU Nanotech, Technical University of Denmark. He is primarily interested in the electronic properties of thin films, in particular atomically thin materials such as graphene. He received his B.Sc. and M.Sc.degrees in Physics and Nanotechnology from Technical University of Denmark (2008/2010), and a Ph.D. (2013) from DTU Photonics where he studied the ultrafast terahertz carrier dynamics of graphene.