We report a study of the complex AC impedance of CVD grown graphene. Wemeasure the explicit frequency dependence of the complex impedance andconductance over the microwave and terahertz range of frequencies using ourrecently developed broadband microwave Corbino and time domain terahertzspectrometers (TDTS). We demonstrate how one may resolve a number of technicaldifficulties in measuring the intrinsic impedance of the graphene layer thatthis frequency range presents, such as distinguishing contributions to theimpedance from the substrate. From our microwave measurements, the AC impedancehas little dependance on temperature and frequency down to liquid heliumtemperatures. The small contribution to the imaginary impedance comes fromeither a remaining residual contribution from the substrate or a smalldeviation of the conductance from the Drude form.
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