Abstract
In this work, we demonstrate the use of electrical impedance spectroscopy (EIS) for the disentanglement of several dielectric contributions in encapsulated single graphene layers. The dielectric data strongly vary qualitatively with the nominal graphene resistance. In the case of sufficiently low resistance of the graphene layers, the dielectric spectra are dominated by inductive contributions, which allow for disentanglement of the electrode/graphene interface resistance from the intrinsic graphene resistance by the application of an adequate equivalent circuit model. Higher resistance of the graphene layers leads to predominantly capacitive dielectric contributions, and the deconvolution is not feasible due to the experimental high frequency limit of the EIS technique.
Highlights
Since the discovery of single-atom graphene layers in the year 2004, large research efforts have been dedicated to the investigation of their fundamental properties and more practical aspects in terms of the handling and incorporation of graphene into functional devices for potential application in the electronics industry [1–11].Single-layer graphene (SLG) is a promising candidate as an electrode material in electrochemical applications [12], and exhibits transparency, superior combined mechanical stability and flexibility and gives rise to several fascinating charge transport phenomena
It was demonstrated here that the extrinsic electrode resistance and the intrinsic graphene resistance of encapsulated graphene layers can be disentangled under certain conditions using electrical impedance spectroscopy (EIS)
In the case of sufficiently low graphene resistance, the dielectric spectra are dominated by inductive contributions, which allows for disentanglement of electrode and graphene resistance by the application of an adequate equivalent circuit model
Summary
Since the discovery of single-atom graphene layers in the year 2004, large research efforts have been dedicated to the investigation of their fundamental properties and more practical aspects in terms of the handling and incorporation of graphene into functional devices for potential application in the electronics industry [1–11].Single-layer graphene (SLG) is a promising candidate as an electrode material in electrochemical applications [12], and exhibits transparency, superior combined mechanical stability and flexibility and gives rise to several fascinating charge transport phenomena. In zero-band gap graphene, metallic or ballistic charge transport has been reported [13–18], whereas variable-range hopping has been observed in semi-conducting graphene [19]. In its pure form, SLG is predicted to be a zero-band gap semiconductor, where the valence and conduction bands touch at the Dirac points in the dispersion relation of electron energy E vs propagation wave vector k [20,21]. Asymmetrical strain distributions in SLG have been shown to lead to the opening of a small band gap [22,23]. Asymmetrical strain can be caused by a small level of warping or bending of the graphene layers, as well as by impurities, where the opening band gap leads to semiconducting charge transport with small activation energies. The electronic properties of bi-layer graphene (BLG) slightly vary, where the band gap may be induced by the application of transverse electric fields [24–26]
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