Characterization of CVD graphene permittivity and conductivity in micro-/millimeter wave frequency range

Abstract

The permittivity and conductivity of chemical vapor deposited monolayer graphene are investigated up to 40 GHz. The characterization method is based on a coplanar waveguide transmission line structure that is fabricated on a multilayer substrate of Si/SiO2/graphene/Al2O3 from the bottom up. The effective relative permittivity of the coplanar waveguide transmission line is extracted using Thru-Reflect-Line calibration and scattering parameter measurements, and then the relative permittivity and corresponding conductivity of graphene are characterized using partial capacitance techniques. The results demonstrate that the conductivity and sheet resistance are remarkably frequency-dependent and that the complex relative permittivity is consistent with the Drude model.

Hybridized Graphene for Supercapacitors: Beyond the Limitation of Pure Graphene

“…Due to good graphene exfoliation and homogeneous dispersion of densely packed AgNPs, an excellent electrical conductivity of 1.3 × 10 7 S m −1 was achieved, which is close to the values of CVD-grown graphene. [86] Both small R S of only 0.97 Ω and equivalent series resistance (ESR) of ≈1.5 Ω were obtained when use the rGO/AgNPs as SC electrodes, as well as an excellent capacitance value of 776 F g −1 at 0.5 A g −1 .…”

Plasma Assisted Reduction of Graphene Oxide Films

“…Using this approach has already demonstrated conductivities in the order of ~10 3 (S/cm) and electron mobility ~900 cm 2 /V.s. To compare, a monolayer film of CVD-graphene has electrical conductivity in the order of 10 4 S/cm [ 270 , 271 ] and an R C/O of 20 [ 272 ]. Certain plasma reduced rGO have attained conductivities in the same magnitude as that of certain highest reported for other techniques such as chemical assisted thermal annealing (acetylene, 1000 °C, 2 h, 1425 S/cm) [ 273 ], joule-heating (>2000 K, 1500 S/cm) [ 274 ], and two-step treatments: thermal annealing (Ar, 1000 K, 1 h) and joule heating (3000 K, 6300 S/cm), and chemical reduction (hydrazine monohydrate) and graphitization (2700 °C, 5770 S/cm) [ 220 ].…”

Concluding remarks: Chemistry of 2-dimensional materials: beyond graphene

“…For example, in applications where high charge conductivity is required, single layer graphene (SLG, σG ~ 10 6 S m -1 ) is by far the best candidate and cannot be substituted for instance with graphene oxide. 10,11 Vice versa, graphene oxide prevails over other graphene related material when water colloidal stability is required. Anyway, trying to set ground rules for classifying materials in a field that is being developed at such a high speed is always complex, because new examples arise, breaking the pre-defined guidelines.…”