W. Liu, R. Valdés Aguilar, Y. Hao, R. S. Ruoff, N. P. Armitage
We report a study of the complex AC impedance of CVD grown graphene. We
measure the explicit frequency dependence of the complex impedance and
conductance over the microwave and terahertz range of frequencies using our
recently developed broadband microwave Corbino and time domain terahertz
spectrometers (TDTS). We demonstrate how one may resolve a number of technical
difficulties in measuring the intrinsic impedance of the graphene layer that
this frequency range presents, such as distinguishing contributions to the
impedance from the substrate. From our microwave measurements, the AC impedance
has little dependance on temperature and frequency down to liquid helium
temperatures. The small contribution to the imaginary impedance comes from
either a remaining residual contribution from the substrate or a small
deviation of the conductance from the Drude form.
View original:
http://arxiv.org/abs/1106.2472
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