Terahertz imaging and spectroscopy of large-area single-layer graphene
  We demonstrate terahertz (THz) imaging and spectroscopy of a 15x15-mm^2 single-layer graphene film on Si using broadband THz pulses. The THz images clearly map out the THz carrier dynamics of the graphene-on-Si sample, allowing us to measure sheet conductivity with sub-mm resolution without fabricating electrodes. The THz carrier dynamics are dominated by intraband transitions and the THz-induced electron motion is characterized by a flat spectral response. A theoretical analysis based on the Fresnel coefficients for a metallic thin film shows that the local sheet conductivity varies across the sample from {\sigma}s = 1.7x10^-3 to 2.4x10^-3 {\Omega}^-1 (sheet resistance, {\rho}s = 420 - 590 {\Omega}/sq). 
J. L. Tomaino, A. D. Jameson, J. W. Kevek, M. J. Paul, A. M. van der   Zande, R. A. Barton, P. L. McEuen, E. D. Minot, Yun-S...
cond-mat.mtrl-sci physics.optics