Sheet conductance and imaging of graphene by terahertz time-domain spectroscopy

A rapid, nondestructive and high-through quality characterization of large-area graphene films is presented based on the Terahertz (THz) time-domain spectroscopy technology. Sheet conductance of graphene films was obtained from the THz transmission measurement and the data analysis was based on the Fresnel coefficient and the Tinkham film equation. In comparison to the traditional four-point probes method, the measurement result showed a quite good consistency. Conductance imaging of graphene by THz method was performed and used to estimate the quality of graphene films on the Si substrate.