▎ 摘　　要

We investigate simple chemical doping process and the optical characterization of large-area graphene. The large-area graphene is grown on copper foil by chemical vapor deposition method, where carrier density is varied by exposure duration within FeCl3 solution after complete etching of copper. Using terahertz time-domain spectroscopy, we obtain terahertz conductivity with different exposure duration. We confirm that the longer exposure time, the higher conductivity, which results from p-type doping due to copper etchant. The result implies that varying etching time during transfer process enables distinguished Fermi levels in graphene sheet, essential for simple fabrication of doping-level-controlled graphene sample.