▎ 摘　　要

We demonstrate terahertz (THz) imaging and spectroscopy of a 15 x 15-mm(2) single-layer graphene film on Si using broadband THz pulses. The THz images clearly map out the THz carrier dynamics of the grapheneon-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) = 1.7 x 10(-3) to 2.4 x 10(-3) Omega(-1) (sheet resistance, rho(s) = 420 - 590 Omega/sq). (C)2010 Optical Society of America